Reduced radius optical fiber with high mechanical reliability.

Abstract

The present disclosure provides an optical fiber having an impact-resistant coating system. The fiber is characterized by low microbend loss and high mechanical reliability. The coating system includes a primary coating and a secondary coating. The primary and secondary coatings have reduced thicknesses to provide a fiber with a reduced radius without sacrificing protection. The primary coating has a low spring constant and a thickness sufficient to resist the transmission of forces to the glass fiber. The secondary coating has high puncture resistance. The outer diameter of the optical fiber is 200 μm or less.

Description

Priority

[0001] This application claims the benefit of priority from Dutch Patent Application No. 2024737, filed January 23, 2020, which in turn claims priority from U.S. Provisional Patent Application No. 62 / 957879, filed January 7, 2020, the contents of which are relied upon and incorporated herein by reference in their entirety. [Technical Field]

[0002] This disclosure relates to optical fibers and optical fiber assemblies. More particularly, this disclosure relates to optical fibers and fiber optic cables designed for subsea environments. Most particularly, this disclosure relates to optical fibers having reduced diameters and fiber optic cables having a large number of optical fibers. [Background technology]

[0003] Optical fibers having reduced diameters are attractive because they reduce the size of ribbons and cables required to accommodate a given total number of optical fibers, increase the total number of optical fibers in a given length of ribbon or cable of a given diameter, reduce the cost of the ribbon or cable, make efficient use of existing infrastructure to upgrade ribbon or cable plants, and reduce the footprint of new ribbon or cable plants.

[0004] Specifically, the demand for submarine optical fiber transmission capacity is increasing, driven by the rapid growth of Internet traffic between different continents. To increase transmission capacity, wavelength division multiplexing has been developed to increase the number of transmission channels, and advanced modulation formats have been developed to increase the data transmission rate per channel. However, the number of channels and the data transmission rate per channel are approaching their practical limits, making it inevitable to increase the number of fibers.

[0005] Submarine cables are designed to protect the fibers inside from water damage and other mechanical damage. Deep-sea cables are typically sized at 17-20 mm in diameter to facilitate installation and reduce vulnerability. Therefore, space for optical fibers is limited, and it is desirable to increase the total number of fibers without increasing the cable size. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, there is a need for optical fibers with reduced diameters to increase the total number of fibers in a fixed size cable. Specifically, there is a need for optical fibers with reduced glass diameters and / or reduced coating thicknesses that provide the performance required for long-distance transmission in subsea environments. [Means for solving the problem]

[0007] The present disclosure provides a small-diameter optical fiber having an impact-resistant coating system and low microbend losses. The optical fiber includes a glass fiber having a radius smaller than the standard radius (62.5 μm) used in the industry. The coating system includes a primary coating and a secondary coating. The modulus and thickness of the secondary coating are configured to provide puncture resistance. The primary coating works in concert with the secondary coating to minimize microbend losses. The primary coating also has high tear strength and is resistant to damage caused by thermal and mechanical stresses generated during the fiber manufacturing process. The radius of the glass fiber and the total thickness of the primary and secondary coatings are configured to provide an optical fiber with an outer radius of 100 μm or less.

[0008] This description is In optical fibers, a core region made of silica glass doped with an alkali metal oxide, having a radius r1 ranging from 3.0 μm to 10.0 μm and a maximum relative refractive index Δ ranging from −0.15% to 0.30%; 1max a core region having a relative refractive index profile Δ1 having a cladding region surrounding and immediately adjacent the core region, the cladding region having a radius r4 in the range of 37.5 μm to 52.5 μm; a primary coating surrounding and immediately adjacent the cladding region, the primary coating having a radius r5 and a spring constant χ p , a primary coating having an in-situ elastic modulus in the range of 0.05 MPa to 0.30 MPa and a thickness r5-r4 in the range of 20.0 μm to 40.0 μm; and a secondary coating surrounding and immediately adjacent to the primary coating, the secondary coating having a radius r6 of 100.0 μm or less, a Young's modulus of greater than 1600 MPa, and a thickness r6-r5 in the range of 15.0 μm to 30.0 μm; The present invention extends to optical fibers having

[0009] Additional features and advantages will be set forth in the detailed description that follows, and in part will become readily apparent to those skilled in the art from that description, or may be learned by practicing the embodiments described in this specification and its claims, as well as the accompanying drawings.

[0010] It is to be understood that both the foregoing general description and the following detailed description are exemplary only and are intended to provide an overview or framework for understanding the nature and character of the claims.

[0011] The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate selected aspects of the present disclosure and, together with the description, serve to explain the principles and operation of methods, products, and compositions encompassed by the present disclosure. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of a coated optical fiber according to one embodiment; [Figure 2] Schematic diagram of a typical optical fiber ribbon [Figure 3] Schematic diagram of a typical optical fiber cable [Figure 4A] A cross-sectional view of an optical fiber having a core region, an inner cladding region, an intermediate cladding region, an outer cladding region, a primary coating, and a secondary coating. [Figure 4B] A cross-sectional view of an optical fiber having a core region, an intermediate cladding region, an outer cladding region, a primary coating, and a secondary coating. [Figure 5A] Relative refractive index profile of a glass fiber having a core region, an inner cladding region, an intermediate cladding region, and an outer cladding region [Figure 5B] Relative refractive index profile of a glass fiber having a core region, an intermediate cladding region, and an outer cladding region [Figure 6] Example relative refractive index profile of a glass fiber [Figure 7] Graph showing the dependence of puncture load on cross-sectional area for three secondary coatings [Figure 8A] Example relative refractive index profile of a glass fiber [Figure 8B] Example relative refractive index profile of a glass fiber [Figure 9] Example relative refractive index profile of a glass fiber [Figure 10] Plot of attenuation as a function of wavelength for two optical fibers DETAILED DESCRIPTION OF THE INVENTION

[0013] The present disclosure is provided as an enabling teaching and may be more readily understood by reference to the following description, drawings, examples, and claims. To this end, those skilled in the relevant art will recognize and appreciate that many changes can be made in various aspects of the embodiments described herein while still obtaining beneficial results. It will also be apparent that some of the desired advantages of the embodiments can be obtained by selecting some of the features without utilizing other features. Accordingly, those skilled in the art will recognize that many modifications and adaptations are possible and may even be desirable in particular circumstances and are a part of this disclosure. Accordingly, it is to be understood that the present disclosure is not limited to the specific compositions, articles, devices, and methods disclosed, unless otherwise specified. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0014] In this specification and in the claims that follow, reference will be made to a number of terms that shall be defined to have the following meanings.

[0015] "Include" or similar terms means including but not limited to, i.e., inclusive and not exclusive.

[0016] As used herein, the term "about" means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not, and need not be, exact, but may be approximate and / or larger or smaller, as desired, to reflect tolerances, conversion factors, rounding, measurement error, and the like, as well as other factors known to those of ordinary skill in the art. When a value is said to be about or approximately equal to a particular numerical value, the value is within ±10% of that numerical value. For example, a value of about 10 refers to values ​​between 9 and 11, inclusive. When the term "about" is used in describing a value or an endpoint of a range, it is to be understood that the disclosure includes the specific value or endpoint referred to. Whether or not a numerical value or range endpoint is referred to herein as "about," the endpoint of that value or range is intended to include both embodiments: those modified by "about" and those not modified by "about." It is further understood that the endpoints of each range are significant both in relation to the other endpoint and independently of the other endpoint.

[0017] The term "about" also applies to all terms within its range unless otherwise specified. For example, about 1, 2, or 3 is equivalent to about 1, about 2, or about 3, including about 1-3, about 1-2, and about 2-3. Specific and preferred values ​​disclosed for compositions, components, ingredients, additives, and similar embodiments, as well as ranges, are for illustrative purposes only and do not exclude other stated values ​​or other values ​​within a stated range. The compositions and methods of the present disclosure include those having any or any combination of the values, specific values, more specific values, and preferred values ​​recited herein.

[0018] Where a numerical range consisting of an upper and lower limit is described herein, unless otherwise stated in specific circumstances, the range is intended to include the endpoints, and all integers and fractions within the range. It is not intended that the scope of the claims be limited to the specific values ​​recited in defining the range. Furthermore, when an amount, concentration, or other value or parameter is given as a range, one or more preferred ranges, or a list of preferred upper and lower limits, this is to be understood as specifically disclosing all ranges formed from any pairing of any upper limit or preferred value with any lower limit or preferred value, regardless of whether such pairs are separately disclosed.

[0019] As used herein, the indefinite article "a" or "an" and its corresponding definite article "the" mean at least one, or one or more, unless otherwise specified.

[0020] As used herein, contact refers to direct or indirect contact. Direct contact refers to contact without an intervening object, while indirect contact refers to contact through one or more intervening objects. Elements in direct contact touch each other. Elements in indirect contact do not touch each other, but touch an intervening object or series of intervening objects, at least one of which touches the other element. Elements in contact may be rigidly or non-rigidly joined. Contact refers to the direct or indirect contact of two elements. Elements in direct (indirect) contact may be said to be in direct (indirect) contact with each other.

[0021] As used herein, "directly adjacent" means in direct contact and "indirectly adjacent" means in indirect contact. The term "adjacent" encompasses elements that are directly or indirectly adjacent to each other.

[0022] An "optical fiber" is a waveguide having a glass portion surrounded by a cladding. The glass portion comprises a core and a cladding. The cladding surrounds and immediately adjacent the core and includes two or more concentric regions having different relative refractive indices. The relative refractive index of the core is greater than the relative refractive index of the cladding. The glass portion of an optical fiber is referred to herein as a "glass fiber."

[0023] "Radial position," "radius," or radial coordinate "r" refers to the radial position relative to the centerline of the glass fiber (r=0).

[0024] The terms "inner" and "outer" are used to refer to relative values ​​of radial coordinates or relative positions of regions of an optical fiber, with "inner" meaning closer to the centerline of the fiber than "outer." The inner radial coordinate is closer to the centerline of the glass fiber than the outer radial coordinate. The inner radial coordinate is between the centerline of the glass fiber and the outer radial coordinate. The inner region of the optical fiber is closer to the centerline of the glass fiber than the outer region. The inner region of the optical fiber is between the centerline of the glass fiber and the outer region of the glass fiber.

[0025] The term "mode" refers to a guided mode. A single-mode fiber is an optical fiber that is designed to support only the fundamental LP01 mode over a significant length of the optical fiber (e.g., at least a few meters), but that is capable, under certain circumstances, of supporting multiple modes over short distances (e.g., tens of centimeters). Here, we assume that the birefringence of the optical fiber is small enough to assume that the two orthogonal polarization components of the LP01 mode are degenerate and propagate with the same phase velocity. A multimode optical fiber is an optical fiber that supports the fundamental LP01 mode and at least one higher-order LP01 mode over a significant length of the optical fiber. nm The optical fiber is designed to support a single mode at a wavelength of 1550 nm, where either n≠0 or m≠1. The optical fiber disclosed herein is preferably a single mode optical fiber.

[0026] The "operating wavelength" of an optical fiber is the wavelength at which the optical fiber operates. The operating wavelength corresponds to the wavelength of the guided mode. Typical operating wavelengths include 850 nm, 980 nm, 1060 nm, 1310 nm, and 1550 nm, which are commonly used in communication systems, optical data links, and data centers. While an optical fiber may be designated with a particular operating wavelength, it is understood that a particular optical fiber may operate at multiple operating wavelengths and / or over a continuous range of operating wavelengths. Properties such as modal bandwidth and mode field diameter may vary with operating wavelength, and the relative refractive index profile of a particular optical fiber may be designed to provide optimal performance at a particular operating wavelength, a particular combination of operating wavelengths, or a particular continuous range of operating wavelengths.

[0027] "Refractive index" refers to the refractive index at a wavelength of 1550 nm.

[0028] A "refractive index profile" is the relationship between refractive index or relative refractive index and radius. For relative refractive index profiles depicted herein as having step boundaries between adjacent core and / or cladding regions, normal variations in processing conditions may result in less than sharp step boundaries at the interfaces of the adjacent regions. While the boundaries of the refractive index profile may be expressed herein as step changes in refractive index, it will be understood that actual boundaries may be rounded or otherwise deviate from a perfect step function characteristic. It will further be understood that the value of the relative refractive index may vary with radial position in either the core and / or cladding regions. When the relative refractive index varies with radial position within a particular region of the fiber (e.g., either the core and / or cladding regions), it will be expressed in terms of its actual or approximate functional dependence, or its value at a specific location within the region, or an average value applicable to the entire region. Unless otherwise specified, when the relative refractive index of a region (e.g., either the core region and / or the cladding region) is expressed as a single value or as a parameter (e.g., Δ or Δ%) that applies to the entire region, it is understood that the relative refractive index within that region is constant, or nearly constant, and corresponds to the single value, or that the single value or parameter represents an average value of the non-constant dependence of the relative refractive index with radial position within that region. For example, if "i" is a region of a glass fiber, then the parameter Δ i Unless otherwise specified, refers to the average value of the relative refractive index within a region as defined by equation (2) below. Whether by design or as a result of normal manufacturing variations, the dependence of the relative refractive index on radial position may be sloped, curved, or otherwise non-constant.

[0029] As used herein, "relative refractive index" refers to the refractive index in formula (1):

[0030]

number

[0031] where ni is the radial position r of the glass fiber unless otherwise specified. i is the refractive index at ref is the refractive index of pure silica glass, unless otherwise specified. Thus, as used herein, relative refractive index percentages are relative to pure silica glass, which has a refractive index of 1.444 at a wavelength of 1550 nm. As used herein, relative refractive index is expressed as Δ (or "delta") or Δ% (or "delta %"), and its value is given in units of "%" unless otherwise specified. Relative refractive index may also be expressed as Δ(r) or Δ(r)%.

[0032] The average relative refractive index (Δ 平均 ) is expressed as equation (2):

[0033]

number

[0034] where r 内側 is the inner radius of the region, and r 外側 is the outer radius of the region and Δ(r) is the relative refractive index of the region.

[0035] The term "α-profile" refers to the formula (3):

[0036]

number

[0037] where r is the radial position at which Δ(r) is a maximum, and r z >r0 is the radial position where Δ(r) decreases to a minimum, and r is the radial position where r i ≦r≦r f where r i is the initial radial position of the α-profile, and r fis the final radial position of the α-profile, where α is a real number. Δ(r0) of the α-profile is now Δ max , or if a specific region i of the fiber is mentioned, Δ i,max The relative refractive index profile of the core region of the fiber is such that r occurs at the centerline (r = 0) and r z corresponds to the outer radius r1 of the core region and is described by an α-profile with Δ1(r1)=0, then equation (3) simplifies to equation (4):

[0038]

number

[0039] The term "super-Gaussian profile" is defined by equation (5):

[0040]

number

[0041] where r is the radial distance from the centerline, γ is a positive number, and a is such that when r=a, Δ=Δ 1max is the radial scaling parameter such that / e.

[0042] The "mode field diameter" or "MFD" of an optical fiber is:

[0043]

number

[0044] where f(r) is the transverse component of the electric field distribution of the guided optical signal and r is the radial position within the fiber. The "mode field diameter" or "MFD" depends on the wavelength of the optical signal and is reported here for a wavelength of 1550 nm. When referring to the mode field diameter herein, that wavelength specific application is made. Unless otherwise specified, the mode field diameter is the LP at a particular wavelength. 01 It is called a mode.

[0045] The "effective area" of an optical fiber is:

[0046]

number

[0047] where f(r) is the transverse component of the electric field of the guided optical signal and r is the radial position within the fiber. eff " depends on the wavelength of the optical signal and is understood here to refer to a wavelength of 1550 nm.

[0048] "Trench region" refers to the cladding region of a glass fiber that is surrounded by and immediately adjacent to the outer cladding region. This trench region has an inner radial coordinate r トレンチ、内側 From the outer radial coordinate r トレンチ、外側 The relative refractive index at all radial positions within this trench region is less than the relative refractive index of the outer cladding region.

[0049] The "trench volume" of the trench region is:

[0050]

number

[0051] where r トレンチ、内側 is the inner radius of the trench region, and r トレンチ、外側is the outer radius of the trench region, Δ is the relative refractive index of the outer cladding region surrounding and immediately adjacent to the trench region, and Δ トレンチ (r) is the relative refractive index of the trench, where r トレンチ、内側 and,r トレンチ、外側 At all radial positions between トレンチ (r)<Δ4. The trench region is also referred to herein as the intermediate cladding region. In this disclosure, r トレンチ、内側 is referred to as r1 (in embodiments without an inner cladding region) or r2 (in embodiments with an inner cladding region), and r トレンチ、外側 is called r3, and Δ トレンチ is called Δ3. V トレンチ is sometimes referred to as V3. The trench volume is defined as an absolute value and has a positive value. The trench volume is defined here as %Δ micrometers 2 , %Δ-micrometers 2 , %Δ-μm 2 or %Δμm 2 and whereby these units can be used interchangeably herein.

[0052] The "cutoff wavelength" of an optical fiber is the minimum wavelength at which the optical fiber supports only one propagation mode. At wavelengths below the cutoff wavelength, multimode transmission can occur, resulting in LP 01Multipath interference between the fiber and one or more higher-order modes can limit the information transmission capacity of an optical fiber. Here, cutoff wavelengths are reported as fiber cutoff wavelengths or cable cutoff wavelengths. The fiber cutoff wavelength is based on a 2-meter fiber length, and the cable cutoff wavelength is based on a 22-meter cable fiber length. The 22-meter cable cutoff wavelength is typically smaller than the 2-meter cutoff wavelength due to higher levels of bending and mechanical stress in the cable environment. The fiber cutoff wavelength, λ, is defined as follows: TIA-455-80: FOTP-80 IEC-60793-1-44 Optical Fibres - Part 1-44: Measurement Methods and Test Procedures - Cut-off Wavelength (May 21, 2003), by the Telecommunications Industry Association (TIA). CF is based on a fiber length of 2 meters, while the cable cutoff wavelength λ CC is based on a cable fiber length of 22 meters.

[0053] The "chromatic dispersion" of an optical fiber (referred to herein as "dispersion" unless otherwise specified) is the sum of material dispersion, waveguide dispersion, and multimode dispersion. For single-mode waveguide fiber, multimode dispersion is zero. Dispersion values ​​in the two-mode region assume that multimode dispersion is zero. The zero-dispersion wavelength (λ0) is the wavelength at which dispersion is zero.

[0054] Primary coating "spring constant" χ p is expressed as equation (9):

[0055]

number

[0056] where E p is the in-situ elastic modulus of the primary coating, and t pis the thickness of the primary coating, and d g where r is the diameter of the glass fiber. The spring constant is a phenomenological parameter that describes the degree to which the primary coating reduces the bonding of the secondary coating to the glass fiber (see J. Baldauf et al., "Relationship of Mechanical Characteristics of Dual Coated Single Mode Optical Fibers and Microbending Loss," IEICE Transactions on Communications, Vol. E76-B, No. 4, pp. 352-357 (1993)). In the phenomenological model, the buffering effect of the primary coating is modeled as a spring with a spring constant given in Equation (9). A lower spring constant results in greater resistance to microbending. The spring constant reflects the tradeoff between in-situ modulus and thickness in establishing the primary coating's resistance to microbending.

[0057] The optical fiber disclosed herein comprises a core region, a cladding region surrounding the core region, and a coating surrounding the cladding region. The core region and the cladding region are glass and define a glass fiber. The cladding region includes multiple regions, at least two of which have different relative refractive indices. In one embodiment, the multiple cladding regions are concentric regions including an intermediate cladding region surrounding and immediately adjacent to the core region, and an outer cladding region surrounding and immediately adjacent to the intermediate cladding region. In another embodiment, the multiple cladding regions are concentric regions including an inner cladding region surrounding and immediately adjacent to the core region, an intermediate cladding region surrounding and immediately adjacent to the inner cladding region, and an outer cladding region surrounding and immediately adjacent to the intermediate cladding region. The intermediate cladding region has a lower relative refractive index than the outer cladding region. The intermediate cladding region, sometimes referred to herein as a trench or trench region, has a trench volume given by Equation (8). The intermediate cladding region may contribute to reducing bend losses. The core region, cladding region, inner cladding region, intermediate cladding region, and outer cladding region are also referred to as the core, cladding, inner cladding, intermediate cladding, and outer cladding, respectively. All embodiments of the optical fiber comprise a glass fiber having a core, an intermediate cladding, and an outer cladding. In some embodiments, the glass fiber also includes an inner cladding between the intermediate cladding and the core; i.e., the inner cladding is optional.

[0058] Whenever used herein, radial position r1 and relative refractive index Δ1 or Δ1(r) refer to the core region, radial position r2 and relative refractive index Δ2 or Δ2(r) refer to the inner cladding region, radial position r3 and relative refractive index Δ3 or Δ3(r) refer to the intermediate cladding region, radial position r4 and relative refractive index Δ4 or Δ4(r) refer to the outer cladding region, radial position r5 refer to the primary coating, radial position r6 refer to the secondary coating, and radial position r7 refer to the tertiary coating.

[0059] The relative refractive index Δ1(r) is the maximum value Δ1max and the minimum value Δ 1min The relative refractive index Δ2(r) has a maximum value Δ 2max and the minimum value Δ 2min The relative refractive index Δ3(r) has a maximum value Δ 3max and the minimum value Δ 3min The relative refractive index Δ4(r) has a maximum value Δ 4max and the minimum value Δ 4min In embodiments where the relative refractive index is constant or nearly constant over a region, the maximum and minimum values ​​of the relative refractive index are equal or nearly equal. Unless otherwise specified, when a single value is reported for the relative refractive index over a region, that single value corresponds to the average value for that region.

[0060] It will be understood that the central core region is substantially cylindrical in shape, and that the surrounding inner cladding region, surrounding intermediate cladding region, surrounding outer cladding region, surrounding primary coating, surrounding secondary coating, and surrounding tertiary coating are substantially annular in shape. The annular regions can be characterized by inner and outer radii. Radial positions r1, r2, r3, r4, r5, r6, and r7 herein refer to the outer radii of the core, inner cladding, intermediate cladding, outer cladding, primary coating, secondary coating, and tertiary coating, respectively. Radius r4 defines the outer boundary of the glass fiber. Radius r6 also corresponds to the outer radius of the optical fiber in embodiments without a tertiary coating. When a tertiary coating is present, radius r7 corresponds to the outer radius of the optical fiber.

[0061] When two regions are immediately adjacent to one another, the outer radius of the inner region of the two regions coincides with the inner radius of the outer region of the two regions. For example, the glass fiber disclosed herein includes an intermediate cladding region surrounded by and immediately adjacent to an outer cladding region. In such an embodiment, radius r3 corresponds to the outer radius of the intermediate cladding region and the inner radius of the outer cladding region.

[0062] As noted above, the inner cladding region is optional. In embodiments having an inner cladding region, radius r2 corresponds to the outer radius of the inner cladding region and the inner radius of the intermediate cladding region. In embodiments not having an inner cladding region, radius r1 corresponds to the outer radius of the core region and the inner radius of the intermediate cladding region. That is, in embodiments not having an inner cladding region, the intermediate cladding region is immediately adjacent to the core region.

[0063] The following terminology applies to embodiments in which the relative refractive index profile includes an inner cladding region surrounding and immediately adjacent to the core, an intermediate cladding region surrounding and immediately adjacent to the inner cladding region, an outer cladding region surrounding and immediately adjacent to the intermediate cladding region, a primary coating surrounding and immediately adjacent to the outer cladding region, and a secondary coating surrounding and immediately adjacent to the primary coating. The difference between radial position r2 and radial position r1 is referred to herein as the thickness of the inner cladding region. The difference between radial position r3 and radial position r2 is referred to herein as the thickness of the intermediate cladding region. The difference between radial position r4 and radial position r3 is referred to herein as the thickness of the outer cladding region. The difference between radial position r5 and radial position r4 is referred to herein as the thickness of the primary coating. The difference between radial position r6 and radial position r5 is referred to herein as the thickness of the secondary coating. The difference between radial position r7 and radial position r6 is referred to herein as the thickness of the tertiary coating.

[0064] The following terminology applies to embodiments in which the intermediate cladding region is immediately adjacent to the core region and the outer cladding region is immediately adjacent to the intermediate cladding region. The difference between radial position r3 and radial position r1 is referred to herein as the thickness of the intermediate cladding region. The difference between radial position r4 and radial position r3 is referred to herein as the thickness of the outer cladding region. The difference between radial position r5 and radial position r4 is referred to herein as the thickness of the primary coating. The difference between radial position r6 and radial position r5 is referred to herein as the thickness of the secondary coating. The difference between radial position r7 and radial position r6 is referred to herein as the thickness of the tertiary coating.

[0065] As described further below, the relative refractive indices of the core region, intermediate cladding region, and outer cladding region are different. The relative refractive index Δ2 of the inner cladding region is less than the relative refractive index Δ1 of the core region and greater than the relative refractive index Δ3 of the intermediate cladding region. The relative refractive index Δ2 of the inner cladding region may be less than, equal to, or greater than the relative refractive index Δ4 of the outer cladding region. Each of these regions is formed from doped or undoped silica glass. The refractive index of the undoped silica glass is altered by including updopants or downdopants at levels designed to provide a targeted refractive index or refractive index profile, using techniques known to those skilled in the art. An updopant is a dopant that increases the refractive index of the glass relative to the undoped glass composition. A downdopant is a dopant that decreases the refractive index of the glass relative to the undoped glass composition. In one embodiment, the undoped glass is pure silica glass. When the undoped glass is pure silica glass, updopants include Cl, Br, Ge, Al, P, Ti, Zr, Nb, and Ta, and downdopants include F and B. Regions of constant refractive index can be formed by either no doping or uniform doping. Regions of varying refractive index can be formed by non-uniform spatial distribution of dopants and / or by including different dopants in different regions. The refractive index varies approximately linearly with the concentration of the updopant or downdopant. For example, each 1% by weight of Cl as a dopant in silica glass increases the relative refractive index by approximately 0.083 Δ%, and each 1% by weight of F as a dopant in silica glass decreases the relative refractive index by approximately 0.32 Δ%.

[0066] The coatings described herein are formed from curable coating compositions. Curable coating compositions include one or more curable components. As used herein, the term "curable" is intended to mean that the component contains one or more curable functional groups that, upon exposure to a suitable curing energy source, can form a covalent bond that links the component to itself or to other components of the coating composition. The product obtained by curing a curable coating composition is referred to herein as the cured product of the composition. Preferably, the cured product is a polymer. The curing process is energy-induced, in the form of radiant energy or thermal energy. In preferred embodiments, curing occurs by radiation, which radiation refers to electromagnetic radiation. Radiation-induced curing is referred to herein as radiation curing or photocuring. A radiation-curable component is one that can be induced to undergo a curing reaction when exposed to radiation of a suitable wavelength and intensity for a sufficient period of time. Suitable wavelengths include those in the infrared, visible, or ultraviolet portions of the electromagnetic spectrum. The radiation curing reaction occurs in the presence of a photoinitiator. A radiation-curable component may also be thermally curable. Similarly, a thermosetting component is one that can be induced to undergo a curing reaction when exposed to thermal energy of sufficient intensity for a sufficient period of time. A thermosetting component may also be radiation-curable.

[0067] A curable component includes one or more curable functional groups. A curable component having only one curable functional group is referred to herein as a monofunctional curable component. A curable component having two or more curable functional groups is referred to herein as a multifunctional curable component. A multifunctional curable component includes two or more functional groups capable of forming covalent bonds during the curing process, and can introduce crosslinks into the polymer network formed during the curing process. A multifunctional curable component is sometimes referred to herein as a "crosslinker" or "curable crosslinker." Curable components include curable monomers and curable oligomers. Examples of functional groups involved in the formation of covalent bonds during the curing process are identified below.

[0068] The term "molecular weight" as applied to polyols refers to the number average molecular weight (M n ) means

[0069] The term "(meth)acrylate" means methacrylate, acrylate, or a combination of methacrylate and acrylate.

[0070] In situ modulus, Young's modulus, % elongation, and tear strength values ​​refer to values ​​determined under measurement conditions according to the procedures described herein.

[0071] Reference will now be made in detail to illustrative embodiments of the present description.

[0072] The optical fiber disclosed herein comprises a glass fiber surrounded by a coating. An example of an optical fiber is shown in schematic cross-section in Figure 1. Optical fiber 10 comprises a glass fiber 11 surrounded by a primary coating 16 and a secondary coating 18. Further description of glass fiber 11, primary coating 16, and secondary coating 18 is provided below.

[0073] FIG. 2 illustrates an optical fiber ribbon 30. The ribbon 30 comprises a plurality of optical fibers 20 and a matrix 32 encapsulating the plurality of optical fibers. The optical fibers 20 comprise a core region, a cladding region, a primary coating, and a secondary coating, as previously described. The optical fibers 20 may also comprise a tertiary coating, as described above. The secondary coating may include a pigment. The optical fibers 20 are arranged in a substantially planar, parallel relationship relative to one another. The optical fibers in the optical fiber ribbon are encapsulated by the ribbon matrix 32 in any known configuration (e.g., edge-bonded ribbon, thin-encapsulated ribbon, thick-encapsulated ribbon, or multi-layer ribbon) by conventional methods of manufacturing optical fiber ribbons. In FIG. 2, the optical fiber ribbon 30 contains twelve (12) optical fibers 20; however, it should be apparent to one skilled in the art that any number of optical fibers 20 (e.g., two or more) may be used to form an optical fiber ribbon 30 configured for a particular application. The ribbon matrix 32 can be formed from the same composition used to prepare the secondary coating, or the ribbon matrix 32 can be formed from a different composition that is otherwise suitable for use.

[0074] FIG. 3 illustrates a fiber optic cable 40. The cable 40 includes a plurality of optical fibers 20 surrounded by a jacket 42. The optical fibers 20 may be tightly or loosely packed in a conduit surrounded by the inner surface 44 of the jacket 42. The number of fibers disposed within the jacket 42 is referred to as the "fiber count" of the fiber optic cable 40. The jacket 42 is formed from an extruded polymeric material and may include multiple concentric layers of polymer or other materials. The fiber optic cable 40 may include one or more strength members (not shown) embedded within the jacket 42 or disposed within a conduit defined by the inner surface 44. The strength members include fibers or rods that are more rigid than the jacket 42. The strength members may be made of metal, braided steel, glass-reinforced plastic, fiberglass, or other suitable materials. The fiber optic cable 40 may include other layers (e.g., armor layers, moisture barriers, ripcords, etc.) surrounded by the jacket 42. The fiber optic cable 40 may have a stranded loose-tube core or other fiber optic cable construction.

[0075] Glass Fiber. The optical fiber disclosed herein comprises a glass fiber having a core region and a cladding region surrounding the core region, and a coating surrounding the cladding region. The core region and the cladding region are glass. The glass fiber 11 comprises a core region 12 and a cladding region 14, as will be familiar to those skilled in the art. The core region 12 has a higher refractive index than the cladding region 14, and the glass fiber 11 functions as a waveguide.

[0076] In many applications, the core and cladding regions have a distinct core-cladding boundary. Alternatively, the core and cladding regions may not have a distinct boundary. One type of fiber is a step-index fiber. Another type of fiber is a graded-index fiber, which has a core region with a refractive index that varies with distance from the center of the fiber. Examples of graded-index fibers are fibers with a core region having a relative refractive index profile with an α-profile defined by equation (4) above or a super-Gaussian profile defined by equation (5) above.

[0077] Schematic cross-sectional views of optical fibers are shown in Figures 4A and 4B. In Figure 4A, optical fiber 46 comprises a core region 48, a cladding region 50, a primary coating 56, and a secondary coating 58. Cladding region 50 comprises an inner cladding region 51, an intermediate cladding region 53, and an outer cladding region 55. In Figure 4B, optical fiber 46 comprises a core region 48, a cladding region 50, a primary coating 56, and a secondary coating 58. Cladding region 50 comprises an intermediate cladding region 53 and an outer cladding region 55.

[0078] A typical relative refractive index profile for a glass fiber is shown in Figures 5A and 5B. Figure 5A shows the outer radius r1 and the maximum relative refractive index Δ 1max 1 shows a rectangular trench profile for glass fiber 60 having a core region (1) with a relative refractive index Δ1 having a value of r1, an inner cladding region (2) extending from radial position r1 to radial position r2 and having a relative refractive index Δ2, an intermediate cladding region (3) extending from radial position r2 to radial position r3 and having a relative refractive index Δ3, and an outer cladding region (4) extending from radial position r3 to radial position r4 and having a relative refractive index Δ4.

[0079] FIG. 5B shows the relationship between the outer radius r1 and the maximum relative refractive index Δ 1max1 shows a rectangular trench profile for a glass fiber 60 having a core region (1) with a relative refractive index Δ1 having a value of r1, an intermediate cladding region (3) extending from radial position r1 to radial position r3 and having a relative refractive index Δ3, and an outer cladding region (4) extending from radial position r3 to radial position r4 and having a relative refractive index Δ4.

[0080] In the profiles of Figures 5A and 5B, the intermediate cladding region (3) is a trench having a constant or average relative refractive index Δ3 that is less than the constant or average relative refractive index Δ4 of the outer cladding region (4). The intermediate cladding region (3) has a trench volume as defined in equation (8) above. The core region (1) has the highest average and maximum relative refractive index in the profile. The core region (1) may include a lower refractive index region (known in the art as a "centerline dip") (not shown) at or near the centerline.

[0081] In the profiles shown in Figures 5A and 5B, the core region (1) of the glass fiber has a graded index with a relative refractive index described by a super-Gaussian profile. The radial position r0 (Δ 1max ) corresponds to the centerline of the fiber (r = 0) and the radial position r of the super-Gaussian profile zcorresponds to the core radius r1. In embodiments with a centerline dip, the radial position r0 is slightly offset from the centerline of the fiber. In other embodiments (not shown), the core region (1) has a step-index relative refractive index profile or an α-profile relative refractive index profile rather than a super-Gaussian profile. In still other embodiments, the core region (1) has a relative refractive index profile that is not defined by an α-profile, a super-Gaussian profile, or a step-index profile. In some embodiments, the relative refractive index Δ1 decreases continuously radially away from the centerline. In other embodiments, the relative refractive index Δ1 varies over some radial positions between the centerline and r1 and includes a constant or near-constant value over other radial positions between the centerline and r1.

[0082] In the profile shown in FIG. 5A, the transition regions 62 from the inner cladding region (2) to the intermediate cladding region (3) and the transition regions 64 from the intermediate cladding region (3) to the outer cladding region (4) are shown as step changes. It should be understood that the step changes are idealized, and that in practice, the transition regions 62 and 64 may not be exactly perpendicular. Instead, the transition regions 62 and / or 64 may have a slope or curvature. When the transition regions 62 and / or 64 are non-perpendicular, the inner radius r2 and outer radius r3 of the intermediate cladding region (3) correspond to the midpoints of the transition regions 62 and 64, respectively. These midpoints correspond to half the depth 67 of the intermediate cladding region (3) relative to the outer cladding region (4).

[0083] The relative order of the relative refractive indices Δ1, Δ2, Δ3, and Δ4 in the relative refractive index profile shown in FIG. 5A is determined by the condition Δ 1max >Δ4>Δ3 and Δ 1max >Δ2>Δ3.

[0084] In the profile shown in Figure 5B, the transition regions 62 from the core region (1) to the intermediate cladding region (3) and the transition regions 64 from the intermediate cladding region (3) to the outer cladding region (4) are shown as step changes. It should be understood that the step changes are idealized, and that in practice, the transition regions 62 and 64 may not be exactly perpendicular. Instead, the transition regions 62 and 64 may have a slope or curvature. When the transition regions 62 and / or 64 are non-perpendicular, the inner radius r2 and outer radius r3 of the intermediate cladding region (3) correspond to the midpoints of the transition regions 62 and 64, respectively. These midpoints correspond to half the depth 67 of the intermediate cladding region (3) relative to the outer cladding region (4).

[0085] The relative order of the relative refractive indices Δ1, Δ3, and Δ4 in the relative refractive index profile shown in FIG. 5B is determined by the condition Δ 1max >Δ4>Δ3.

[0086] The core region is made of silica glass. Preferably, the silica glass of the core region does not contain Ge. That is, the core region is made of Ge-free silica glass. The silica glass of the core region can be undoped, up-doped, and / or down-doped silica glass. Up-doped silica glass includes silica glass doped with an alkali metal oxide (e.g., Na2O, KO, Li2O, Cs2O, or Rb2O). Down-doped silica glass includes silica glass doped with F. In some embodiments, the core region is doped with both an alkali metal oxide and fluorine. The concentration of the alkali metal oxide (e.g., KO) in the core, expressed in terms of the amount of alkali metal (e.g., K), ranges from 20 ppm to 500 ppm, or from 35 ppm to 400 ppm, or from 50 ppm to 300 ppm, where ppm refers to parts per million by mass.

[0087] In some embodiments, the core region includes updopants and downdopants, where the concentration of the updopants is highest at the centerline (r=0) and lowest at radius r1, and the concentration of the downdopants is lowest at the centerline (r=0) and highest at radius r1. In such embodiments, the relative refractive index Δ1 may have a positive value near the centerline (r=0) and decrease to a negative value at radius r1.

[0088] In one embodiment, the core region is a segmented core region comprising an inner core region surrounded by an outer core region, where the inner core region is made of updoped silica glass and has a positive maximum relative refractive index Δ 1max and the outer core region is made of down-doped silica glass and has a minimum negative relative refractive index Δ 1min The updoped silica glass of the inner core region comprises an updopant or a combination of updopants and downdopants. In embodiments where the inner core region comprises a combination of updopants and downdopants, the relative concentrations of the updopants and downdopants are adjusted to provide the maximum net positive value of the relative refractive index. In embodiments where the outer core region comprises a combination of updopants and downdopants, the relative concentrations of the updopants and downdopants are adjusted to provide the maximum net negative value of the relative refractive index. In embodiments relating to a segmented core, Δ1 (and Δ 1max and Δ 1min ) refers to the entire core region, including the inner core region and the outer core region, r1 corresponds to the outer radius of the outer core region, and r a corresponds to the outer radius of the inner core region. The boundary between the inner and outer core regions is at the radial position r a occurs at r a <r1である。

[0089] In some embodiments, the relative refractive index of the core region of the glass fiber is described by an α-profile having an α value in the range of 1.5 to 10, or in the range of 1.7 to 8.0, or in the range of 1.8 to 6.0, or in the range of 1.9 to 5.0, or in the range of 1.95 to 4.5, or in the range of 2.0 to 4.0, or in the range of 4.0 to 9.5, or in the range of 5.0 to 9.0, or in the range of 10 to 100, or in the range of 11 to 40, or in the range of 12 to 30. As the value of α increases, the relative refractive index more closely approaches a step profile. In some embodiments relating to a segmented core region, either or both of the inner and outer core regions have a relative refractive index described by an α-profile having a value of α as described herein.

[0090] The outer radius r1 of the core region is in the range of 3.0 μm to 10.0 μm, or in the range of 3.5 μm to 9.0 μm, or in the range of 4.0 μm to 8.0 μm. In some embodiments, the core region includes a portion having a constant or approximately constant relative refractive index with a radial width of at least 1.0 μm, or at least 2.0 μm, or at least 3.0 μm, or at least 4.0 μm, or at least 5.0 μm, or in the range of 1.0 μm to 6.0 μm, or in the range of 2.0 μm to 5.0 μm. In some embodiments, the portion of the core region having a constant or approximately constant relative refractive index has ... 1min In an embodiment with a segmented core region, the radius r a is in the range of 0.25 μm to 3.0 μm, or in the range of 0.5 μm to 2.5 μm, or in the range of 0.75 μm to 2.0 μm.

[0091] The relative refractive index of the core region, Δ1 or Δ 1max is in the range of −0.15% to 0.30%, or −0.10% to 0.20%, or −0.05% to 0.15%, or 0.00% to 0.10%. 1minis in the range of −0.20% to 0.10%, or in the range of −0.15% to 0.05%, or in the range of −0.15% to 0.00%.

[0092] In some embodiments, the relative refractive index of the core region is Δ 1max is described by a step-like profile with a constant or nearly constant value corresponding to

[0093] The inner cladding region is made of undoped silica glass, updoped silica glass, or downdoped silica glass. The relative refractive index Δ2 of the inner cladding region is in the range of −0.60% to 0.00%, or −0.55% to −0.05%, or −0.50% to −0.10%, or −0.45% to −0.15%. The relative refractive index Δ2 is preferably constant or nearly constant. The difference between Δ2 and Δ3 (or Δ2 and Δ 3min difference, or Δ 2max and Δ3, or Δ 2max and Δ 3min The difference between the refractive index Δ2 of the inner cladding region and the refractive index Δ4 of the outer cladding region is greater than 0.10%, or greater than 0.15%, or greater than 0.20%, or greater than 0.25%, or greater than 0.30%, or in the range of 0.10% to 0.40%, or in the range of 0.15% to 0.35%. The relative refractive index Δ2 of the inner cladding region is less than, equal to, or greater than the relative refractive index Δ4 of the outer cladding region.

[0094] The inner radius of the inner cladding region is r1 and has the value given above. The outer radius of the inner cladding region r2 is in the range of 6.0 μm to 18.0 μm, or in the range of 7.0 μm to 16.0 μm, or in the range of 8.0 μm to 14.0 μm. The thickness of the inner cladding region r2-r1 is in the range of 2.0 μm to 10.0 μm, or in the range of 3.0 μm to 9.0 μm, or in the range of 4.0 μm to 8.0 μm.

[0095] The intermediate cladding region is made of down-doped silica glass. The preferred down-dopant is F (fluorine). The F (fluorine) concentration is in the range of 0.1% to 2.5% by weight, or in the range of 0.25% to 2.25% by weight, or in the range of 0.3% to 2.0% by weight.

[0096] In embodiments where the relative refractive index profile includes an intermediate cladding region, the relative refractive index Δ or Δ 3min is in the range of -0.30% to -0.90%, or -0.30% to -0.70%, or -0.30% to -0.60%, or -0.30% to -0.50%, or -0.35% to -0.75%, or -0.35% to -0.60%, or -0.40% to -0.70%, or -0.45% to -0.70%. It is preferred that the relative refractive index Δ3 is constant or approximately constant. Δ 1max and Δ3 (or Δ 1max and Δ 3min or the difference between Δ1 and Δ3, or the difference between Δ1 and Δ 3min The difference between Δ is greater than 0.20%, or greater than 0.30%, or greater than 0.40%, or greater than 0.50%, or greater than 0.60%, or in the range of 0.25% to 0.70%, or in the range of 0.35% to 0.60%. 1min and Δ3 (or Δ 1min and Δ 3min (difference between) is greater than 0.20%, or greater than 0.30%, or greater than 0.40%, or greater than 0.50%, or in the range of 0.20% to 0.60%, or in the range of 0.25% to 0.50%.

[0097] The inner radius of the intermediate cladding region is r1 (in embodiments without an inner cladding region) or r2 (in embodiments with an inner cladding region) and has the value specified above. The outer radius r3 of the intermediate cladding region is in the range of 10.0 μm to 30.0 μm, or in the range of 12.5 μm to 27.5 μm, or in the range of 15.0 μm to 25.0 μm. The thickness r3-r1 (in embodiments without an inner cladding region) or thickness r3-r2 (in embodiments with an inner cladding region) of the intermediate cladding region is in the range of 2.0 μm to 22.0 μm, or in the range of 5.0 μm to 20.0 μm, or in the range of 7.5 μm to 17.5 μm, or in the range of 10.0 μm to 15.0 μm.

[0098] In embodiments having an inner cladding region, the trench volume V of the intermediate cladding region トレンチ is 20% μm 2 More than or 30% μm 2 More than or 40% μm 2 More than or 50% μm 2 Over or 60% μm 2 More than or 20% μm 2 to 70% μm 2 range, or 25% μm 2 to 65% μm 2 range, or 30% μm 2 to 60% μm 2 The trench volume can be controlled by varying the thickness of the intermediate cladding region, the relative refractive index of the intermediate cladding region, and / or the difference between the relative refractive index of the outer cladding region and the relative refractive index of the intermediate cladding region.

[0099] In embodiments without an inner cladding region, the trench volume V of the intermediate cladding region トレンチ is 10%μm 2 More than or 15% μm 2 More than or 20% μm 2 More than or 25% μm 2 More than or 30% μm 2 More than or 10.0% μm 2 to 40.0% μm2 range, or 15.0% μm 2 to 35.0% μm 2 range, or 20.0% μm 2 to 30.0% μm 2 The trench volume can be controlled by varying the thickness of the intermediate cladding region, the relative refractive index of the intermediate cladding region, and / or the difference between the relative refractive index of the outer cladding region and the relative refractive index of the intermediate cladding region.

[0100] The relative refractive index of the outer cladding region, Δ4 or Δ 4max is in the range of -0.60% to 0.00%, or in the range of -0.55% to -0.05%, or in the range of -0.50% to -0.10%, or in the range of -0.45% to -0.15%, or in the range of -0.40% to -0.20%, or in the range of -0.35% to -0.25%. It is preferred that the relative refractive index Δ4 is ​​constant or approximately constant. The difference between Δ4 and Δ3 (or Δ4 and Δ 3min difference, or Δ 4max and Δ3, or Δ 4max and Δ 3min (difference between) is greater than 0.10%, or greater than 0.20%, or greater than 0.25%, or greater than 0.30%, or greater than 0.35%, or in the range of 0.10% to 0.45%, or in the range of 0.15% to 0.40%.

[0101] The inner radius of the outer cladding region is r3 and has the value specified above. The outer radius r4 is preferably small to minimize the diameter of the glass fibers for a high total fiber count in the cable. The outer radius r4 of the outer cladding region is equal to or less than 52.5 μm, or equal to or less than 50.0 μm, or equal to or less than 47.5 μm, or equal to or less than 45.0 μm, or equal to or less than 42.5 μm, or equal to or less than 40.0 μm, or in the range of 37.5 μm to 52.5 μm, or in the range of 37.5 μm to 50.0 μm, or in the range of 37.5 μm to 47.5 μm, or in the range of 40.0 μm to 52.5 μm, or in the range of 40.0 μm to 50.0 μm, or in the range of 40.0 μm to 47.5 μm, or in the range of 42.5 μm to 50.0 μm. The thickness r4-r3 of the outer cladding region is in the range of 15.0 μm to 40.0 μm, or in the range of 17.5 μm to 37.5 μm, or in the range of 20.0 μm to 35.0 μm, or in the range of 22.5 μm to 32.5 μm.

[0102] Figure 6 shows representative relative refractive index profiles of fabricated glass fibers. Relative refractive index profiles 70 and 80 include, in increasing diameter, a core region, an intermediate cladding region, and an outer cladding region. Relative refractive index profiles 90 and 100 include, in increasing diameter, a core region, an inner cladding region, an intermediate cladding region, and an outer cladding region. The width and depth of the intermediate cladding region vary. Relative refractive index profile 70 includes a transition region 73 between the core region and the depressed-index cladding region and a transition region 77 between the depressed-index cladding region and the outer cladding region. For relative refractive index profile 70, transition region 73 occurs at radius r1, and transition region 77 occurs at radius r3. Relative refractive index profile 80 includes a transition region 83 between the core region and the depressed-index cladding region and a transition region 87 between the depressed-index cladding region and the outer cladding region. For relative refractive index profile 80, transition region 83 occurs at radius r1, and transition region 87 occurs at radius r3. Relative refractive index profile 90 comprises a transition region 93 between the inner and intermediate cladding regions and a transition region 97 between the intermediate and outer cladding regions. For relative refractive index profile 90, transition region 93 occurs at a radius r2, and transition region 97 occurs at a radius r3. Relative refractive index profile 100 comprises a transition region 103 between the inner and intermediate cladding regions and a transition region 107 between the intermediate and outer cladding regions. For relative refractive index profile 100, transition region 103 occurs at a radius r2, and transition region 107 occurs at a radius r3.

[0103] The effective areas A associated with the relative refractive index profiles 70, 80, 90, and 100 shown in FIG. eff are at a wavelength of 1550 nm and 76 μm, respectively. 2 , 86 μm 2 , 112 μm 2 , and 150 μm 2 is.

[0104] In one embodiment, the core region is a segmented core region where the inner core region is surrounded by and directly adjacent to the outer core region, and the outer core region is surrounded by and directly adjacent to an inner cladding region (in embodiments having an inner cladding region) or an intermediate cladding region (in embodiments without an inner cladding region). The outer core region has a radius r1, and the inner core region has an outer diameter r a such that r a < r1. In one embodiment, each of the inner core region and the outer core region has a relative refractive index profile depicted by an α-profile. In one embodiment, the inner core region has an α value in the range of 1.5 to 10, or 1.7 to 8.0, or 1.8 to 6.0, or 1.9 to 5.0, or 1.95 to 4.5, or 2.0 to 4.0, or 4.0 to 9.5, or 5.0 to 9.0, or 10 to 100, or 11 to 40, or 12 to 30. In another embodiment, the inner core region has a relative refractive index profile depicted by an α-profile, and the outer core region has a relative refractive index profile depicted by a step-type refractive index profile. In another embodiment, the inner core region has a relative refractive index profile depicted by an α-profile, and the outer core region has a relative refractive index profile depicted by a rounded step-type refractive index profile.

[0105] In one embodiment, the inner core region is alkali-doped silica, and the outer core region is halide-doped silica. The halide-doped silica includes silica doped with one or more of Cl, F, and Br. In one embodiment, the inner core region is silica doped with K2O, and the outer core region is doped with F or a combination of F and Cl.

[0106] In an embodiment where each of the inner core region and the outer core region has a relative refractive index profile depicted by an α-profile, the radius r a is given by Equation (10):

[0107]

number

[0108] The function χ given to 2 where f(r i ) is the α-profile function of the inner core region, and g(r j ) is the α-profile function of the outer core region, and g(r a ) is r j =r a g(r j ) and Δ(r i ) is the measured relative refractive index profile of the inner core region, and Δ(r j ) is the measured relative refractive index profile of the outer core region, and the subscript “i” corresponds to the radial position r within the inner core region. i The subscript "j" indicates the radial position r j Displays 0 <r i <r a , r a ≦r j ≦r b , the subscript "a" is r i =r a The value of the subscript "i" corresponds to r j = The value of the subscript "j" corresponding to r1.

[0109] The effective area A of the optical fiber disclosed herein eff is 1550nm wavelength, 70μm 2 Over or 80 μm 2 Over or 90 μm 2 Over 100 μm 2 Over 120 μm 2 Over 70 μm 2 to 160 μm 2 range, or 80 μm 2 to 120 μm 2 range, or 90 μm 2 to 110 μm 2 is in the range.

[0110] The optical fiber disclosed herein has an attenuation of 0.180 dB / km or less, or 0.175 dB / km or less, or 0.170 dB / km or less, or 0.165 dB / km or less, or 0.160 dB / km or less at a wavelength of 1550 nm.

[0111] The mode field diameter of the optical fiber disclosed herein is in the range of 9.5 μm to 11.5 μm, or in the range of 9.75 μm to 11.25 μm, or in the range of 10.0 μm to 11.0 μm at a wavelength of 1550 nm.

[0112] The cable cutoff wavelength λ of the optical fiber disclosed herein CC is less than 1550 nm, or less than 1530 nm, or less than 1500 nm, or less than 1450 nm, or less than 1400 nm, or less than 1350 nm.

[0113] Optical Fiber Coatings. The transmittance of light through an optical fiber depends largely on the properties of the coating applied to the glass fiber. The coating typically includes a primary coating and a secondary coating, where the secondary coating surrounds the primary coating and the primary coating contacts the glass fiber (which includes a central core region surrounded by a cladding region). The secondary coating is a harder material (higher Young's modulus) than the primary coating and is designed to protect the glass fiber from damage caused by abrasion or external forces that occur during processing, handling, and deployment of the optical fiber. The primary coating is a softer material (lower Young's modulus) than the secondary coating and is designed to buffer or dissipate stresses resulting from forces applied to the outer surface of the secondary coating. Dissipating stresses within the primary coating attenuates the stresses and minimizes their reaching the glass fiber. The primary coating is particularly important in dissipating stresses caused by microbends that the optical fiber encounters when installed in a cable. Microbending stresses transmitted to the glass fiber create local perturbations in the refractive index profile of the glass fiber, so minimizing microbending stresses is essential. Localized refractive index perturbations result in intensity losses in light transmitted through the glass fiber. By dissipating stress, the primary coating minimizes microbend-induced intensity losses.

[0114] It is preferable that the primary coating 16 have a higher refractive index than the cladding region of the glass fiber to keep errant optical signals away from the core region. The primary coating should maintain adequate adhesion to the glass fiber during thermal and hydrolytic degradation, yet be strippable from the glass fiber for splicing purposes.

[0115] The primary and secondary coatings are typically formed by applying a curable coating composition to the glass fiber as a viscous liquid and curing it. The optical fiber may also include a tertiary coating (not shown) surrounding and directly adjacent to the secondary coating. The tertiary coating may contain a pigment, ink, or other colorant to mark the optical fiber for identification purposes and typically has a Young's modulus similar to that of the secondary coating. The thickness of the tertiary coating is less than 10.0 μm, or less than 8.0 μm, or less than 6.0 μm, or less than 4.0 μm, or in the range of 1.0 μm to 10.0 μm, or in the range of 2.0 μm to 8.0 μm, or in the range of 3.0 μm to 6.0 μm.

[0116] Primary Coating Composition. The Primary Coating is the cured product of the curable Primary Coating Composition. The curable Primary Coating Composition provides the optical fiber with a Primary Coating that exhibits a low Young's modulus, low pull-out force, and strong cohesion. The curable Primary Coating Composition further enables the formation of a Primary Coating that is characterized by high resistance to defect formation during stripping operations and clean strippability. The low pull-out force promotes clean stripping of the Primary Coating with minimal residue, and the strong cohesion prevents defects from initiating and propagating in the Primary Coating when exposed to stripping forces. Even with reduced Primary Coating thicknesses, the optical fiber is expected to exhibit low loss and low microbend loss performance. The Primary Coating exhibits these advantages even at reduced thicknesses.

[0117] The Primary Coating is the cured product of a radiation-curable Primary Coating composition containing an oligomer, a monomer, a photoinitiator, and, optionally, additives. The following disclosure describes oligomers of the radiation-curable Primary Coating composition, radiation-curable Primary Coating compositions containing at least one of the oligomers, cured products of radiation-curable Primary Coating compositions containing at least one of the oligomers, glass fibers coated with radiation-curable Primary Coating compositions containing at least one of the oligomers, and glass fibers coated with cured products of radiation-curable Primary Coating compositions containing at least one of the oligomers.

[0118] Preferably, the oligomer comprises a polyetherurethane diacrylate compound and a di-adduct compound. In one embodiment, the polyetherurethane diacrylate compound has a linear molecular structure. In one embodiment, the oligomer is formed from a reaction between a diisocyanate compound, a polyol compound, and a hydroxyacrylate compound, which produces a polyetherurethane diacrylate compound as a major product and a di-adduct compound as a minor product. The reaction forms a urethane bond upon reaction of the isocyanate groups of the diisocyanate compound with the alcohol groups of the polyol compound. The hydroxyacrylate compound reacts to quench any residual isocyanate groups present in the composition formed from the reaction of the diisocyanate compound and the polyol compound. As used herein, the term "quench" refers to the conversion of an isocyanate group by chemical reaction with a hydroxyl group of the hydroxyacrylate compound. Quenching of residual isocyanate groups with a hydroxy acrylate compound converts the terminal isocyanate groups to terminal acrylate groups.

[0119] Preferred diisocyanate compounds are those of formula (I):

[0120] [ka]

[0121] which comprises two terminal acrylate groups separated by a linking group R1. In one embodiment, the linking group R1 comprises an alkylene group. The alkylene group of the linking group R1 is linear (e.g., methylene or ethylene), branched (e.g., isopropylene), or cyclic (e.g., cyclohexylene, phenylene). The cyclic group is aromatic or non-aromatic. In some embodiments, the linking group R1 is a 4,4'-methylenebis(cyclohexyl) group and the diisocyanate compound is 4,4'-methylenebis(cyclohexyl isocyanate). In some embodiments, the linking group R1 is free of aromatic groups, free of phenylene groups, or free of oxyphenylene groups.

[0122] The polyol compound has the molecular formula (II):

[0123] [ka]

[0124] wherein R2 comprises an alkylene group, -O-R2- is a repeating alkoxylene group, and x is an integer. Preferably, x is greater than 20, or greater than 40, or greater than 50, or greater than 75, or greater than 100, or greater than 125, or greater than 150, or in the range of 20 to 500, or in the range of 20 to 300, or in the range of 30 to 250, or in the range of 40 to 200, or in the range of 60 to 180, or in the range of 70 to 160, or in the range of 80 to 140. R2 is preferably a linear or branched alkylene group such as methylene, ethylene, propylene (unbranched, iso, or a combination thereof), or butylene (unbranched, iso, secondary, tertiary, or a combination thereof). The polyol compound may be a polyalkylene oxide, such as polyethylene oxide, or a polyalkylene glycol, such as polypropylene glycol. Polypropylene glycol is a preferred polyol. The molecular weight of the polyol is greater than 1000 g / mol, or greater than 2500 g / mol, or greater than 5000 g / mol, or greater than 7500 g / mol, or greater than 10000 g / mol, or in the range of 1000 g / mol to 20000 g / mol, or in the range of 2000 g / mol to 15000 g / mol, or in the range of 2500 g / mol to 12500 g / mol, or in the range of 2500 g / mol to 10000 g / mol, or in the range of 3000 g / mol to 7500 g / mol, or in the range of 3000 g / mol to 6000 g / mol, or in the range of 3500 g / mol to 5500 g / mol. In some embodiments, the polyol is polydisperse, comprising molecules spanning a range of molecular weights such that the total number of molecules combine to give the number average molecular weight as defined above.

[0125] The degree of unsaturation of the polyol is less than 0.25 meq / g, or less than 0.15 meq / g, or less than 0.10 meq / g, or less than 0.08 meq / g, or less than 0.06 meq / g, or less than 0.04 meq / g, or less than 0.02 meq / g, or less than 0.01 meq / g, or less than 0.005 meq / g, or in the range of 0.001 meq / g to 0.15 meq / g, or in the range of 0.005 meq / g to 0.10 meq / g, or in the range of 0.01 meq / g to 0.10 meq / g, or in the range of 0.01 meq / g to 0.05 meq / g, or in the range of 0.02 meq / g to 0.10 meq / g, or in the range of 0.02 meq / g to 0.05 meq / g. As used herein, unsaturation refers to the value determined by the standard method reported in ASTM D4671-16. In that method, a polyol is reacted with mercuric acetate and methanol in a methanol solution to produce the compound acetoxymercuricmethoxy and acetic acid. The reaction of the polyol with mercuric acetate is equimolar, and the amount of acetic acid released is determined by titration with alcoholic potassium hydroxide to provide the measure of unsaturation used herein. To prevent excess mercuric acetate from interfering with the acetic acid titration, sodium bromide is added to convert the mercuric acetate to bromide.

[0126] The reaction to form the oligomer further includes the addition of a hydroxyacrylate compound to react with terminal isocyanate groups present in unreacted starting materials (e.g., diisocyanate compounds) or with the product formed in the reaction of the diisocyanate compound with a polyol (e.g., a urethane compound having terminal isocyanate groups). The hydroxyacrylate compound reacts with the terminal isocyanate groups to provide terminal acrylate groups for one or more components of the oligomer. In some embodiments, the hydroxyacrylate compound is present in an amount in excess of that required to completely convert the terminal isocyanate groups to terminal acrylate groups. The oligomer includes a single polyetherurethane acrylate compound or a combination of two or more polyetherurethane acrylate compounds.

[0127] The hydroxyacrylate compound has the molecular formula (III):

[0128] [ka]

[0129] wherein R3 comprises an alkylene group. The alkylene group of R3 may be linear (e.g., methylene or ethylene), branched (e.g., isopropylene), or cyclic (e.g., phenylene). In some embodiments, the hydroxyacrylate compound comprises substitution of an ethylenically unsaturated group on the acrylate group. The substituent on the ethylenically unsaturated group comprises an alkyl group. An example of a hydroxyacrylate compound having a substituted ethylenically unsaturated group is a hydroxymethacrylate compound. The following discussion describes hydroxyacrylate compounds. However, it should be understood that the discussion applies to substituted hydroxyacrylate compounds, particularly hydroxymethacrylate compounds.

[0130] In various embodiments, the hydroxyacrylate compound includes a hydroxyalkyl acrylate, such as 2-hydroxyethyl acrylate. The hydroxyacrylate compound may contain residual or higher levels of water. The presence of water in the hydroxyacrylate compound may promote the reaction of the isocyanate groups to reduce the concentration of unreacted isocyanate groups in the final reaction composition. In various embodiments, the water content of the hydroxyacrylate compound is at least 300 ppm, or at least 600 ppm, or at least 1000 ppm, or at least 1500 ppm, or at least 2000 ppm, or at least 2500 ppm.

[0131] In the above exemplary molecular formulas (I), (II), and (III), the groups R1, R2, and R3 are independently all the same, all different, or include two groups that are the same and one group that is different.

[0132] The diisocyanate compound, hydroxyacrylate compound, and polyol compound can be combined and reacted simultaneously, or combined and reacted sequentially (in any order). In one embodiment, an oligomer is formed by reacting a diisocyanate compound with a hydroxyacrylate compound and reacting the resulting product composition with a polyol compound. In another embodiment, an oligomer is formed by reacting a diisocyanate compound with a polyol compound and reacting the resulting product composition with a hydroxyacrylate compound.

[0133] The oligomer is formed from the reaction of a diisocyanate compound, a hydroxyacrylate compound, and a polyol compound, wherein the molar ratio of diisocyanate compound to hydroxyacrylate compound to polyol compound during the reaction is n:m:p. n, m, and p are referred to herein as the number of moles or molar ratio of diisocyanate, hydroxyacrylate, and polyol, respectively. The moles n, m, and p can be positive integers or positive non-integer numbers. In embodiments, when p is 2.0, n is in the range of 3.0 to 5.0, or 3.2 to 4.8, or 3.4 to 4.6, or 3.5 to 4.4, or 3.6 to 4.2, or 3.7 to 4.0, and m is in the range of 1.5 to 4.0, or 1.6 to 3.6, or 1.7 to 3.2, or 1.8 to 2.8, or 1.9 to 2.4. For values ​​of p other than 2.0, the molar ratio n:m:p is scaled proportionally. For example, a molar ratio of n:m:p=4.0:3.0:2.0 corresponds to a molar ratio of n:m:p=2.0:1.5:1.0.

[0134] The number of moles m may be selected to provide an amount of hydroxyacrylate compound that will stoichiometrically react with any unreacted isocyanate groups present in the product composition formed from the reaction of the diisocyanate compound and polyol compound used to form the oligomer. The isocyanate groups may be present in the unreacted diisocyanate compound (unreacted starting material) or in the isocyanate-terminated urethane compound formed in the reaction of the diisocyanate compound with the polyol compound. Alternatively, the number of moles m may be selected to provide an amount of hydroxyacrylate compound in excess of the amount necessary to stoichiometrically react with any unreacted isocyanate groups present in the product composition formed from the reaction of the diisocyanate compound and the polyol compound. The hydroxyacrylate compound is added in a single aliquot or multiple aliquots. In one embodiment, an initial aliquot of hydroxyacrylate is included in the reaction mixture used to form the oligomer, and the resulting product composition can be tested for the presence of unreacted isocyanate groups (e.g., using FTIR spectroscopy to detect the presence of isocyanate groups). Additional aliquots of hydroxyacrylate compounds may be added to the resulting composition to stoichiometrically react with unreacted isocyanate groups (e.g., until the characteristic isocyanate frequency (e.g., 2260 cm) is reached when the isocyanate groups are converted by the hydroxyacrylate compound). -1 From 2270cm -1 ) using FTIR spectroscopy to monitor the decrease in hydroxyacrylate compound. In an alternative embodiment, an aliquot of hydroxyacrylate compound is added in excess of the amount required to stoichiometrically react with the unreacted isocyanate groups. As described more fully below, for a given value of p, the ratio of moles m to moles n affects the relative proportions of polyetherurethane diacrylate compound and diaddition compound in the oligomer, with differences in the relative proportions of polyetherurethane diacrylate compound and diaddition compound resulting in differences in the tear strength and / or critical stress of coatings formed from the oligomer.

[0135] In one embodiment, the oligomer is formed from a reaction mixture comprising 4,4'-methylenebis(cyclohexyl isocyanate), 2-hydroxyethyl acrylate, and polypropylene glycol in the molar ratio n:m:p as defined above, wherein the polypropylene glycol has a number average molecular weight in the range of 2500 g / mol to 6500 g / mol, or in the range of 3000 g / mol to 6000 g / mol, or in the range of 3500 g / mol to 5500 g / mol.

[0136] The oligomer comprises two components. The first component has the molecular formula (IV):

[0137] [ka]

[0138] and the second component is a polyether urethane diacrylate compound having the molecular formula (V):

[0139] [ka]

[0140] wherein the groups R1, R2, R3, and the integer x are as previously described herein, and y is a positive integer; the group R1 in molecular formulas (IV) and (V) is the same as the group R1 in molecular formula (I); the group R2 in molecular formula (IV) is the same as the group R2 in molecular formula (II); and the group R3 in molecular formulas (IV) and (V) is the same as the group R3 in molecular formula (III). The diaddition compound corresponds to a compound formed by reaction of both terminal isocyanate groups of a diisocyanate compound of molecular formula (I) with a hydroxyacrylate compound of molecular formula (II), wherein the diisocyanate compound has not undergone reaction with a polyol of molecular formula (II).

[0141] The diaddition compound is formed from the reaction of a diisocyanate compound with a hydroxyacrylate compound during the reaction used to form the oligomer. Alternatively, the diaddition compound is formed independently of the reaction used to form the oligomer and added to the product of the reaction used to form the polyetherurethane diacrylate compound or to the purified form of the polyetherurethane diacrylate compound. The hydroxy group of the hydroxyacrylate compound reacts with the isocyanate group of the diisocyanate compound to provide a terminal acrylate group. This reaction occurs with each isocyanate group of the diisocyanate compound to form the diaddition compound. The di-addition compound is present in the oligomer in an amount of at least 1.0% by weight, or at least 1.5% by weight, or at least 2.0% by weight, or at least 2.25% by weight, or at least 2.5% by weight, or at least 3.0% by weight, or at least 3.5% by weight, or at least 4.0% by weight, or at least 4.5% by weight, or at least 5.0% by weight, or at least 7.0% by weight, or at least 9.0% by weight, or in the range of 1.0% to 10.0% by weight, or in the range of 2.0% to 9.0% by weight, or in the range of 2.5% to 6.0% by weight, or in the range of 3.0% to 8.0% by weight, or in the range of 3.0% to 5.0% by weight, or in the range of 3.0% to 5.5% by weight, or in the range of 3.5% to 5.0% by weight, or in the range of 3.5% to 7.0% by weight. Note that the diadduct concentration is expressed as weight percent of the oligomer, not weight percent of the coating composition.

[0142] An exemplary reaction for synthesizing an oligomer according to the present disclosure is shown in formula (VI):

[0143] [ka]

[0144] a diisocyanate compound (4,4'-methylenebis(cyclohexyl isocyanate), also referred to herein as H12MDI) and a polyol (M n about 4000 g / mole of polypropylene glycol, also referred to herein as PPG4000, where "~" represents the urethane linkage formed by reaction of the terminal isocyanate group of H12MDI with the terminal alcohol group of PPG4000, ~H12MDI, ~H12MDI~, and ~PPG4000~ refer to the residues of H12MDI and PPG4000 remaining after the reaction, and M n refers to the number average molecular weight. The polyetherurethane diisocyanate compound has repeating units of the type ~(H12MDI~PPG4000)~. The specific polyetherurethane diisocyanate shown contains two PPG4000 units. This reaction may also provide a product with one PPG4000 unit, or three or more PPG4000 units. The polyetherurethane diisocyanate and any unreacted H12MDI contain terminal isocyanate groups. According to the present disclosure, a hydroxy acrylate compound (2-hydroxyethyl acrylate, referred to herein as HEA) is included in the reaction to react with the terminal isocyanate groups, converting them to terminal acrylate groups. The conversion of the terminal isocyanate groups to terminal acrylate groups results in quenching of the isocyanate groups. The amount of HEA included in the reaction may be that amount predicted to react stoichiometrically with the predicted concentration of unreacted isocyanate groups, or an amount in excess of the predicted stoichiometric amount. The reaction of HEA with the polyetherurethane diisocyanate compound produces a compound of formula (VII):

[0145] [ka]

[0146] and / or a polyether urethane acrylate compound having formula (VIII):

[0147] [ka]

[0148] and upon reaction of the HEA with unreacted H12MDI, a polyether urethane diacrylate compound having the formula (IX):

[0149] [ka]

[0150] where, as previously noted, ~ represents a urethane linkage and ~HEA represents the residue of HEA remaining after the reaction to form the urethane linkage (consistent with formulas (IV) and (V)). The combination of the polyether urethane diacrylate compound and the di-addition compound in the resulting composition constitutes an oligomer in accordance with the present disclosure. As described more fully below, when one or more oligomers are used in a coating composition, coatings with improved tear strength and critical stress characteristics are obtained. Specifically, oligomers with a high proportion of the di-addition compound have been shown to provide coatings with high tear strength and / or high critical stress values.

[0151] The above reaction is shown for the exemplary combination of H12MDI, HEA, and PPG4000, but can be generalized to any combination of diisocyanate compounds, hydroxyacrylate compounds, and polyols, where the hydroxyacrylate compounds react with terminal isocyanate groups to form terminal acrylate groups, and urethane linkages are formed by reaction of the isocyanate groups with alcohol groups on the polyol or hydroxyacrylate compound.

[0152] The oligomer has the formula (X):

[0153] [ka]

[0154] and a compound which is a polyether urethane diacrylate compound of formula (XI):

[0155] [ka]

[0156] The relative proportions of diisocyanate compound, hydroxy acrylate compound, and polyol used in the reaction correspond to the molar numbers n, m, and p disclosed above.

[0157] For example, compounds represented by the above molecular formulas (I) and (II) may be reacted to form compounds represented by the molecular formula (XII):

[0158] [ka]

[0159] where y is the same as y in formula (IV) and is 1, or 2, or 3 or 4 or more, and x is determined by the number of repeat units of the polyol (as described above).

[0160] Further reaction of the polyether urethane isocyanate of molecular formula (VI) with the hydroxy acrylate of molecular formula (III) gives the polyether urethane isocyanate of molecular formula (IV) listed above and repeated below:

[0161] [ka]

[0162] where y is 1, or 2, or 3, or 4 or more, and x is determined by the number of repeat units of the polyol (as described above).

[0163] In certain embodiments, the reaction between a diisocyanate compound, a hydroxyacrylate compound, and a polyol produces a series of polyetherurethane diacrylate compounds in which y varies such that the average value of y across the distribution of compounds present in the final reaction mixture is a non-integer. In certain embodiments, the average value of y in the polyetherurethane diisocyanates and polyetherurethane diacrylates of molecular formulas (VI) and (IV) corresponds to p or p-1, where p is as defined above. In certain embodiments, the average number of occurrences of the group R1 in the polyetherurethane diisocyanates and polyetherurethane diacrylates of molecular formulas (XII) and (IV) corresponds to n, where n is as defined herein.

[0164] The relative proportions of polyetherurethane diacrylate and diaddition compound produced in the reaction are controlled by varying the molar ratios of n, m, and p. As an illustration, consider the case where p = 2.0. In the theoretical limit of complete reaction, two equivalents of polyol (p) react with three equivalents of diisocyanate (n) to produce a compound having the molecular formula (VI) where y = 2. This compound contains two terminal isocyanate groups, which can be quenched by the subsequent addition of the theoretical limit of two equivalents of hydroxyacrylate compound (m) to form the corresponding polyetherurethane diacrylate compound (IV) where y = 2. For this situation, a theoretical molar ratio of n:m:p = 3.0:2.0:2.0 is defined.

[0165] Within the theoretical limits of the preceding example, reacting a diisocyanate, a hydroxyacrylate, and a polyol at a theoretical molar ratio of n:m:p = 3.0:2.0:2.0 yields a polyetherurethane diacrylate compound having molecular formula (IV) where y = 2 without forming a diaddition compound. Varying the moles n, m, and p controls the relative proportions of polyetherurethane diacrylate and diaddition compound formed in the reaction. For example, increasing the mole number n relative to the mole number m or the mole number p will increase the amount of diaddition compound formed in the reaction. Reaction of a diisocyanate compound, a hydroxyacrylate compound, and a polyol compound at a molar ratio of n:m:p, for example, where n is in the range of 3.0 to 5.0, m is within ±15% of 2n-4, or within ±10% of 2n-4, or within ±5% of 2n-4, and p is 2.0, produces a sufficient amount of diaddition compound in the oligomer to achieve desirable primary coating properties. As an example, an embodiment where n=4.0, m is within ±15% of 2n-4, and p=2.0 means that n=4.0, m is within ±15% of 4, and p=2.0, which means that n=4.0, m is in the range of 3.4 to 4.6, and p=2.0.

[0166] Varying the relative ratio of the diaddition compound and polyetherurethane diacrylate can be achieved through the variation of the mole numbers n, m, and p, and through such variation, it is possible to precisely control the Young's modulus, in-situ modulus, tear strength, critical stress, tensile toughness, and other mechanical properties of coatings formed from coating compositions containing the oligomers. In one embodiment, property control can be achieved by varying the number of polyol units in the polyetherurethane diacrylate compound (e.g., p = 2.0 vs. p = 3.0 vs. p = 4.0). In another embodiment, control of tear strength, tensile toughness, and other mechanical properties is achieved by varying the ratio of the polyetherurethane diacrylate compound and the diaddition compound. For a polyetherurethane compound with a given number of polyol units, oligomers can be prepared with varying ratios of the diaddition compound. The variability in the ratio of the two addition compounds can be fine-tuned to provide oligomers based on polyether urethane diacrylate compounds with a certain number of polyol units that provide coatings exhibiting precise or targeted values ​​of tear strength, critical stress, tensile toughness, or other mechanical properties.

[0167] An oligomer comprising a polyether urethane acrylate compound represented by molecular formula (IV) and a di-addition compound represented by molecular formula (V), wherein the concentration of the di-addition compound in the oligomer is at least 1.0% by weight, or at least 1.5% by weight, or at least 2.0% by weight, or at least 2.25% by weight, or at least 2.5% by weight, or at least 3.0% by weight, or at least 3.5% by weight, or at least 4.0% by weight, or at least 4.5% by weight, or at least 5. Fiber primary coatings are improved when a primary coating composition containing an oligomer in the range of 0.0 wt.%, or at least 7.0 wt.%, or at least 9.0 wt.%, or in the range of 1.0 wt.% to 10.0 wt.%, or in the range of 2.0 wt.% to 9.0 wt.%, or in the range of 3.0 wt.% to 8.0 wt.%, or in the range of 3.5 wt.% to 7.0 wt.%, or in the range of 2.5 wt.% to 6.0 wt.%, or in the range of 3.0 wt.% to 5.5 wt.%, or in the range of 3.5 wt.% to 5.0 wt.% is used. Note that the di-addition concentration is expressed in wt.% of oligomer, not wt.% of the coating composition. The concentration of the di-addition compound is increased in one embodiment by changing the molar ratio n:m:p of diisocyanate:hydroxyacrylate:polyol. In one aspect, a molar ratio n:m:p rich in diisocyanate to polyol promotes the formation of the di-addition compound.

[0168] In the exemplary stoichiometric ratio n:m:p=3:2:2 described above, the reaction proceeds with p equivalents of polyol, n=p+1 equivalents of diisocyanate, and 2 equivalents of hydroxyacrylate. When the mole number n exceeds p+1, the diisocyanate compound is in excess relative to the amount of polyol compound required to form the polyether urethane acrylate of molecular formula (IV). The presence of excess diisocyanate shifts the distribution of reaction products in a direction that favors the formation of a diaddition compound.

[0169] The amount of hydroxyacrylate can also be increased to promote the formation of the diaddition compound with excess diisocyanate compound. For every equivalent of diisocyanate above the stoichiometric mole number n = p + 1, two equivalents of hydroxyacrylate are required to form the diaddition compound. For any mole number p (polyol), the stoichiometric mole numbers n (diisocyanate) and m (hydroxyacrylate) are p + 1 and 2, respectively. When the mole number n is greater than the stoichiometric value, the equivalents of hydroxyacrylate required to completely react the excess diisocyanate to form the diaddition compound can be expressed as m = 2 + 2[n - (p + 1)], where the leading term "2" represents the equivalent of hydroxyacrylate required to terminate the polyether urethane acrylate compound (the compound having the molecular formula (V)), and the term 2[n - (p + 1)] represents the equivalent of hydroxyacrylate required to convert the excess starting diisocyanate to the diaddition compound. If the actual value of moles m is less than this equivalent number, the available hydroxyacrylate will react with isocyanate groups present on oligomers or free diisocyanate molecules to form terminal acrylate groups. The relative kinetics of the two reaction pathways will affect the relative amounts of polyetherurethane diacrylate and diadduct formed, and the deficiency of hydroxyacrylate relative to the amount required to quench all unreacted isocyanate groups can be controlled to further influence the relative proportions of polyetherurethane diacrylate and diadduct formed in this reaction.

[0170] In some embodiments, the reaction includes heating a reaction composition formed from a diisocyanate compound, a hydroxyacrylate compound, and a polyol. The heating promotes the conversion of the terminal isocyanate groups to terminal acrylate groups by reaction of the hydroxyacrylate compound with the terminal isocyanate groups. In different embodiments, the hydroxyacrylate compound is present in excess in the initial reaction mixture and / or is otherwise available or added in unreacted form to effect the conversion of the terminal isocyanate groups to terminal acrylate groups. The heating is at a temperature above 40°C for at least 12 hours, or above 40°C for at least 18 hours, or above 40°C for at least 24 hours, or above 50°C for at least 12 hours, or above 50°C for at least 18 hours, or above 50°C for at least 24 hours, or above 60°C for at least 12 hours, or above 60°C for at least 18 hours, or above 60°C for at least 24 hours.

[0171] In certain embodiments, the conversion of terminal isocyanate groups on the polyetherurethane diacrylate compound or the starting diisocyanate compound (either the initial unreacted amount or the amount present in excess) to terminal acrylate groups is facilitated by adding a supplemental amount of a hydroxyacrylate compound to the reaction mixture. As noted above, the amount of hydroxyacrylate compound required to quench (neutralize) the terminal isocyanate groups may deviate from the theoretical equivalent number due to, for example, incomplete reaction or the desire to control the relative ratios of the polyetherurethane diacrylate compound and the diaddition compound. As noted above, once the reaction has proceeded to completion or other endpoint, it is preferable to quench (neutralize) the remaining isocyanate groups to provide a stabilized reaction product. In certain embodiments, supplemental hydroxyacrylate is added to achieve this goal.

[0172] In one embodiment, the amount of supplemental hydroxy acrylate compound is in addition to the amount included in the initial reaction. The presence of terminal isocyanate groups at any stage of the reaction can be determined, for example, by FTIR spectroscopy (e.g., at 2265 cm -1 The reaction is monitored by a method using a characteristic isocyanate stretching mode near the end of the reaction mixture (using a characteristic isocyanate stretching mode near the end of the reaction mixture), and supplemental hydroxyacrylate compound is added as needed until the intensity of the characteristic stretching mode of the isocyanate group becomes insignificant or below a predetermined threshold. In one embodiment, the supplemental hydroxyacrylate compound is added in excess of the amount necessary to completely convert the terminal isocyanate groups to terminal acrylate groups. In a different embodiment, the supplemental hydroxyacrylate compound is included in the initial reaction mixture (in an amount in excess of the theoretical amount predicted from the molar amounts of diisocyanate and polyol), added as the reaction progresses, and / or added after the reaction of the diisocyanate and polyol compounds has reached completion or has occurred to a predetermined extent.

[0173] The amount of hydroxyacrylate compound in excess of the amount required to completely convert the isocyanate groups is referred to herein as an excess amount of hydroxyacrylate compound, which, when added, is at least 20% of the additional hydroxyacrylate compound required to completely convert the terminal isocyanate groups to terminal acrylate groups, or at least 40% of the additional hydroxyacrylate compound required to completely convert the terminal isocyanate groups to terminal acrylate groups, or at least 60% of the additional amount of hydroxyacrylate compound required to completely convert the terminal isocyanate groups to terminal acrylate groups, or at least 90% of the additional amount of hydroxyacrylate compound required to completely convert the terminal isocyanate groups to terminal acrylate groups.

[0174] In certain embodiments, the amount of supplemental hydroxy acrylate compound may be sufficient to completely or nearly completely quench residual isocyanate groups present in the oligomer formed in the reaction. Quenching isocyanate groups is desirable because isocyanate groups are relatively unstable and often undergo reactions over time. Such reactions can alter the properties of the reaction composition or oligomer, causing inconsistencies in coatings formed therefrom. Reaction compositions and products formed from starting diisocyanates and polyol compounds that are free of residual isocyanate groups are expected to have greater stability and predictable properties.

[0175] The oligomer of the Primary Coating Composition comprises a polyetherurethane diacrylate compound and a di-addition compound as described above. In some embodiments, the oligomer comprises two or more polyetherurethane diacrylate compounds and / or two or more di-addition compounds. The oligomer content of the Primary Coating Composition comprises the total amount of one or more polyetherurethane diacrylate compounds and one or more di-addition compounds, and is greater than 20%, or greater than 30%, or greater than 40%, or in the range of 20% to 80%, or in the range of 30% to 70%, or in the range of 40% to 60% by weight, and the concentration of the di-addition compounds within the oligomer content is as described above.

[0176] The curable Primary Coating Composition further comprises one or more monomers selected to be compatible with the oligomer, to control the viscosity of the Primary Coating Composition for ease of processing, and / or to influence the physical or chemical properties of the coating formed as a cured product of the Primary Coating Composition. The monomers include radiation-curable monomers such as ethylenically unsaturated compounds, ethoxylated acrylates, ethoxylated alkylphenol monoacrylates, propylene oxide acrylate, n-propylene oxide acrylate, isopropylene oxide acrylate, monofunctional acrylates, monofunctional aliphatic epoxy acrylates, multifunctional acrylates, multifunctional aliphatic epoxy acrylates, and combinations thereof.

[0177] Representative radiation-curable ethylenically unsaturated monomers include alkoxylated monomers having one or more acrylate or methacrylate groups. Alkoxylated monomers include one or more alkoxylene groups, which have the form -OR-, where R is a linear or branched alkylene group. Examples of alkoxylene groups include ethoxylene (-O-CH-CH-), n-propoxylene (-O-CH-CH-CH-), isopropoxylene (-O-CH-CH(CH)-, or -O-CH(CH)-CH-). As used herein, the degree of alkoxylation refers to the number of alkoxylene groups in a monomer. In one embodiment, the alkoxylene groups are consecutively linked in the monomer.

[0178] In some embodiments, the primary coating composition has the form R4-R5-O-(CH(CH3)CH2-O) q -C(O)CH=CH2 (where R4 and R5 are aliphatic, aromatic, or a mixture of both, and q=1 to 10), or R4-O-(CH(CH3)CH2-O) q It includes alkoxylated monomers of the formula -C(O)CH=CH2, where C(O) is a carbonyl group, R1 is aliphatic or aromatic, and q=1 to 10.

[0179] Representative examples of monomers include lauryl acrylate (e.g., SR335 available from Sartomer Company, Inc., AGEFLEX FA12 available from BASF, and PHOTOMER 4812 available from IGM Resins), ethoxylated nonylphenol acrylate (e.g., SR504 available from Sartomer Company, Inc., and PHOTOMER 4066 available from IGM Resins), caprolactone acrylate (e.g., SR495 available from Sartomer Company, Inc., and TONE M-100 available from Dow Chemical), phenoxyethyl acrylate (e.g., SR339 available from Sartomer Company, Inc., AGEFLEX PEA available from BASF, and PHOTOMER 4035 available from IGM Resins), isooctyl acrylate (e.g., SR440 available from Sartomer Company, Inc., and AGEFLEX FA12 available from BASF), and PHOTOMER 4812 available from IGM Resins. FA8), tridecyl acrylate (e.g., SR489 available from Sartomer Company, Inc.), isobornyl acrylate (e.g., SR506 available from Sartomer Company, Inc., and AGEFLEX IBOA available from CPS Chemical Co.), tetrahydrofurfuryl acrylate (e.g., SR285 available from Sartomer Company, Inc.), stearyl acrylate (e.g., SR257 available from Sartomer Company, Inc.), isodecyl acrylate (e.g., SR395 available from Sartomer Company, Inc., and AGEFLEX FA10 available from BASF), 2-(2-ethoxyethoxy)ethyl acrylate (e.g., SR256 available from Sartomer Company, Inc.), epoxy acrylate (e.g., CN120 available from Sartomer Company, Inc., and Cytec Industries Inc.ethylenically unsaturated monomers such as EBECRYL 3201 and 3604 available from Sartomer Co., Ltd.), lauryloxyglycidyl acrylate (e.g., CN130 available from Sartomer Company, Inc.), and phenoxyglycidyl acrylate (e.g., CN131 available from Sartomer Company, Inc.), and combinations thereof.

[0180] In some embodiments, the monomer component of the primary coating composition includes a multifunctional (meth)acrylate. Multifunctional ethylenically unsaturated monomers include multifunctional acrylate monomers and multifunctional methacrylate monomers. Multifunctional acrylates are acrylates having two or more polymerizable acrylate moieties per molecule or three or more polymerizable acrylate moieties per molecule. Examples of polyfunctional (meth)acrylates include dipentaerythritol monohydroxypentaacrylate (e.g., PHOTOMER 4399 available from IGM Resins); methylolpropane polyacrylates, with or without alkoxylation, such as trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate (e.g., PHOTOMER 4355, IGM Resins); alkoxylated glyceryl triacrylates, such as propoxylated glyceryl triacrylate with a propoxylation of 3 or more (e.g., PHOTOMER 4096, IGM Resins); and pentaerythritol tetraacrylate (e.g., SR295 available from Sartomer Company, Inc., West Chester, Pennsylvania), ethoxylated pentaerythritol tetraacrylate (e.g., SR494, Sartomer Company, Inc.), dipentaerythritol pentaacrylate (e.g., PHOTOMER 4399, IGM Resins, and SR399, Sartomer Company, Inc.), tripropylene glycol diacrylate, propoxylated hexanediol diacrylate, tetrapropylene glycol diacrylate, pentapropylene glycol diacrylate, and the like, with or without alkoxylation, erythritol polyacrylate, methacrylate analogs of the foregoing, and combinations thereof.

[0181] In some embodiments, the primary coating composition comprises an N-vinyl amide monomer, such as N-vinyl lactam, or N-vinyl pyrrolidinone, or N-vinyl caprolactam, wherein the N-vinyl amide monomer is present in the coating composition at a concentration greater than 1.0 wt.%, or greater than 2.0 wt.%, or greater than 3.0 wt.%, or in the range of 1.0 wt.% to 15.0 wt.%, or in the range of 2.0 wt.% to 10.0 wt.%, or in the range of 3.0 wt.% to 8.0 wt.%.

[0182] In one embodiment, the primary coating composition comprises one or more monofunctional acrylate or methacrylate monomers in an amount of 15% to 90% by weight, or 30% to 75% by weight, or 40% to 65% by weight. In another embodiment, the primary coating composition comprises one or more monofunctional aliphatic epoxy acrylate or methacrylate monomers in an amount of 5% to 40% by weight, or 10% to 30% by weight.

[0183] In one embodiment, the monomer component of the primary coating composition includes a hydroxy-functional monomer. Hydroxy-functional monomers are monomers that have pendant hydroxy moieties in addition to other reactive functional groups, such as (meth)acrylates. Examples of hydroxy-functional monomers containing pendant hydroxyl groups include caprolactone acrylate (available from Dow Chemical as TONE M-100); poly(alkylene glycol) mono(meth)acrylates such as poly(ethylene glycol) monoacrylate, poly(propylene glycol) monoacrylate, and poly(tetramethylene glycol) monoacrylate (each available from Monomer, Polymer & Dajac Labs); and 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate (each available from Aldrich).

[0184] In certain embodiments, the hydroxy-functional monomer is present in an amount sufficient to improve adhesion of the Primary Coating to the optical fiber. The hydroxy-functional monomer is present in the coating composition in an amount between about 0.1% and about 25% by weight, or between about 5% and about 8% by weight. The use of a hydroxy-functional monomer may reduce the amount of adhesion promoter required for adequate adhesion of the Primary Coating to the optical fiber. The use of a hydroxy-functional monomer will also tend to increase the hydrophilicity of the coating. Hydroxy-functional monomers are described in more detail in U.S. Pat. No. 6,563,996, the disclosure of which is incorporated herein by reference in its entirety.

[0185] In different embodiments, the total monomer content of the primary coating composition is between about 15% and about 90% by weight, or between about 30% and about 75% by weight, or between about 40% and about 65% by weight.

[0186] In addition to the curable monomer and oligomer, the curable primary coating composition also contains a polymerization initiator. The polymerization initiator facilitates initiation of the polymerization process associated with curing the coating composition to form a coating. Polymerization initiators include thermal initiators, chemical initiators, electron beam initiators, and photoinitiators. Photoinitiators include ketone photoinitiators and / or phosphine oxide photoinitiators. When used to cure the coating composition, the photoinitiator is present in an amount sufficient to allow for a rapid radiation effect.

[0187] Representative photoinitiators include 1-hydroxycyclohexylphenyl ketone (e.g., IRGACURE 184 available from BASF); bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylphenylphosphine oxide (e.g., commercial blends IRGACURE 1800, 1850, and 1700 available from BASF); 2,2-dimethoxy-2-phenylacetophenone (e.g., IRGACURE 651 available from BASF); bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (IRGACURE 819); (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (LUCIRIN TPO, available from BASF, Munich, Germany); ethoxy(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (LUCIRIN TPO-L available from BASF); and combinations thereof.

[0188] The coating composition includes a single photoinitiator or a combination of two or more photoinitiators, and the total photoinitiator content of the coating composition is up to about 10% by weight, or between about 0.5% and about 6% by weight.

[0189] The curable Primary Coating composition optionally contains one or more additives, such as adhesion promoters, strength additives, antioxidants, catalysts, stabilizers, optical brighteners, property-enhancing additives, amine synergists, waxes, lubricants, and / or slip agents. Some additives act to control the polymerization process, thereby affecting the physical properties (e.g., modulus, glass transition temperature) of the polymerization product formed from the coating composition. Other additives affect the integrity of the cured product of the Primary Coating Composition (e.g., protecting against depolymerization or oxidative degradation).

[0190] Adhesion promoters are compounds that promote adhesion of the primary coating and / or primary composition to glass (e.g., the cladding of a glass fiber). Suitable adhesion promoters include alkoxysilanes, mercapto-functional silanes, organic titanates, and zirconates. Representative adhesion promoters include mercaptoalkylsilanes or mercaptoalkoxysilanes, such as 3-mercaptopropyl-trialkoxysilane (e.g., 3-mercaptopropyl-trimethoxysilane, available from Gelest, Tarrytown, Pennsylvania); bis(trialkoxysilyl-ethyl)benzene; acryloxypropyltrialkoxysilanes (e.g., (3-acryloxypropyl)-trimethoxysilane, available from Gelest), methacryloxypropyltrialkoxysilane, vinyltrialkoxysilane, bis(trialkoxysilylethyl)hexane, allyltrialkoxysilane, styrylethyltrialkoxysilane, and bis(trimethoxysilylethyl)benzene (available from United Chemical Technologies, Bristol, Pennsylvania); see U.S. Pat. No. 6,316,516, the disclosure of which is incorporated herein by reference in its entirety.

[0191] The adhesion promoter is present in the primary coating composition in an amount between 0.02% and 10.0% by weight, or between 0.05% and 4.0% by weight, or between 0.1% and 4.0% by weight, or between 0.1% and 3.0% by weight, or between 0.1% and 2.0% by weight, or between 0.1% and 1.0% by weight, or between 0.5% and 4.0% by weight, or between 0.5% and 3.0% by weight, or between 0.5% and 2.0% by weight, or between 0.5% and 1.0% by weight.

[0192] An exemplary antioxidant is thiodiethylenebis[3-(3,5-di-tert-butyl)-4-hydroxy-phenyl)propionate] (e.g., IRGANOX 1035, available from BASF). In some embodiments, the antioxidant is present in the coating composition in an amount greater than 0.25 wt%, or greater than 0.50 wt%, or greater than 0.75 wt%, or greater than 1.0 wt%, or in an amount ranging from 0.25 wt% to 3.0 wt%, or in an amount ranging from 0.50 wt% to 2.0 wt%, or in an amount ranging from 0.75 wt% to 1.5 wt%.

[0193] Representative optical brighteners include TINOPAL OB (available from BASF); Blankophor KLA (available from Bayer); bisbenzoxazole compounds; phenylcoumarin compounds; and bis(styryl)biphenyl compounds. In one embodiment, the optical brightener is present in the coating composition at a concentration of 0.005% to 0.3% by weight.

[0194] Representative amine synergists include triethanolamine, 1,4-diazabicyclo[2.2.2]octane (DABCO), triethylamine, and methyldiethanolamine. In certain embodiments, the amine synergist is present in a concentration of 0.02% to 0.5% by weight.

[0195] Primary Coating - Properties. Relevant properties of the primary coating include radius, thickness, Young's modulus, and in-situ modulus.

[0196] The radius r5 of the primary coating is 85.0 μm or less, or 80.0 μm or less, or 75.0 μm or less, or 70.0 μm or less, or in the range of 57.5 μm to 92.5 μm, or in the range of 60.0 μm to 90.0 μm, or in the range of 62.5 μm to 87.5 μm, or in the range of 65.0 μm to 85.0 μm, or in the range of 67.5 μm to 82.5 μm.

[0197] To facilitate the reduction in the diameter of the optical fiber, it is preferable to minimize the primary coating thickness r5-r4. The primary coating thickness r5-r4 may be in the range of 20.0 μm to 45.0 μm, or in the range of 20.0 μm to 42.5 μm, or in the range of 20.0 μm to 40.0 μm, or in the range of 20.0 μm to 37.5 μm, or in the range of 20.0 μm to 35.0 μm, or in the range of 22.5 μm to 45.0 μm, or in the range of 22.5 μm to 42.5 μm, or in the range of 22.5 μm to 42.5 μm. In the range of 5 μm to 40.0 μm, or in the range of 22.5 μm to 37.5 μm, or in the range of 22.5 μm to 35.0 μm, or in the range of 25.0 μm to 45.0 μm, or in the range of 25.0 μm to 42.5 μm, or in the range of 25.0 μm to 40.0 μm, or in the range of 25.0 μm to 37.5 μm, or in the range of 25.0 μm to 35.0 μm.

[0198] To promote effective stress buffering and protection of the glass fiber, the primary coating preferably has a low Young's modulus and / or a low in-situ elastic modulus. The Young's modulus of the primary coating is 0.7 MPa or less, or 0.6 MPa or less, or 0.5 MPa or less, or 0.4 MPa or less, or 0.3 MPa or less, or in the range of 0.2 MPa to 0.7 MPa, or in the range of 0.3 MPa to 0.6 MPa. The in-situ elastic modulus of the primary coating is 0.40 MPa or less, or 0.35 MPa or less, or 0.30 MPa or less, or 0.25 MPa or less, or 0.20 MPa or less, or 0.15 MPa or less, or 0.10 MPa or less, or in the range of 0.05 MPa to 0.40 MPa, or in the range of 0.05 MPa to 0.30 MPa, or in the range of 0.05 MPa to 0.25 MPa, or in the range of 0.10 MPa to 0.25 MPa.

[0199] Secondary Coating - Composition. The Secondary Coating is the cured product of a curable Secondary Coating composition that includes a monomer, a photoinitiator, an optional oligomer, and optional additives. This disclosure describes optional oligomers for the radiation-curable Secondary Coating composition, radiation-curable Secondary Coating compositions, cured products of the radiation-curable Secondary Coating compositions, optical fibers coated with the radiation-curable Secondary Coating compositions, and optical fibers coated with the cured products of the radiation-curable Secondary Coating compositions.

[0200] The Secondary Coating is formed as the cured product of a radiation-curable Secondary Coating composition that includes a monomer component having one or more monomers. Preferably, the monomer comprises an ethylenically unsaturated compound. The one or more monomers may be present in an amount of 50% by weight or greater, or from about 60% to about 99% by weight, or from about 75% to about 99% by weight, or from about 80% to about 99% by weight, or from about 85% to about 99% by weight. In one embodiment, the Secondary Coating is the radiation-cured product of a Secondary Coating composition that includes a urethane acrylate monomer.

[0201] The monomers include functional groups that are polymerizable groups and / or groups that promote or enable crosslinking. The monomers may be monofunctional or polyfunctional. In combinations of two or more monomers, the monomer component may be a monofunctional monomer, a polyfunctional monomer, or a combination of a monofunctional monomer and a polyfunctional monomer. In one embodiment, the monomer component of the curable secondary coating composition includes an ethylenically unsaturated monomer. Suitable functional groups for the ethylenically unsaturated monomer include, without limitation, (meth)acrylate, acrylamide, N-vinylamide, styrene and substituted styrene, vinyl ether, vinyl ester, acid ester, and combinations thereof.

[0202] In one embodiment, the monomer component of the curable secondary coating composition comprises an ethylenically unsaturated monomer. The monomer comprises a functional group that is a polymerizable group and / or a group that promotes or enables crosslinking. The monomer may be a monofunctional monomer or a polyfunctional monomer. In combinations of two or more monomers, the monomer component may be a monofunctional monomer, a polyfunctional monomer, or a combination of a monofunctional monomer and a polyfunctional monomer. Suitable functional groups for the ethylenically unsaturated monomer include, without limitation, (meth)acrylate, acrylamide, N-vinylamide, styrene and substituted styrene, vinyl ether, vinyl ester, acid ester, and combinations thereof.

[0203] Exemplary monofunctional ethylenically unsaturated monomers of the curable secondary coating composition include, without limitation, hydroxyalkyl acrylates such as 2-hydroxyethyl-acrylate, 2-hydroxypropyl-acrylate, and 2-hydroxybutyl-acrylate; methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, amyl acrylate, isobutyl acrylate, t-butyl acrylate, pentyl acrylate, isoamyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, isooctyl acrylate, Long- and short-chain alkyl acrylates such as ethyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, isodecyl acrylate, undecyl acrylate, dodecyl acrylate, lauryl acrylate, octadecyl acrylate, and stearyl acrylate; aminoalkyl acrylates such as dimethylaminoethyl acrylate, diethylaminoethyl acrylate, and 7-amino-3,7-dimethyloctyl acrylate; butoxyethyl acrylate, phenoxyethyl acrylate (e.g., SR339, Sartomer Company, Inc.), and alkoxyalkyl acrylates such as ethoxyethoxyethyl acrylate; cyclohexyl acrylate, benzyl acrylate, dicyclopentadiene acrylate, dicyclopentanyl acrylate, tricyclodecanyl acrylate, bornyl acrylate, isobornyl acrylate (e.g., SR423, Sartomer Company, Inc.), tetrahydrofurfuryl acrylate (e.g., SR285, Sartomer Company, Inc.), caprolactone acrylate (e.g., SR495, Sartomer Company, Inc.).), and acryloylmorpholine; alcohol-based acrylates such as polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, methoxyethylene glycol acrylate, methoxypolypropylene glycol acrylate, methoxypolyethylene glycol acrylate, ethoxydiethylene glycol acrylate, and various alkoxylated alkylphenol acrylates such as ethoxylated (4) nonylphenol acrylate (e.g., Photomer 4066, IGM Resins); acrylamides such as diacetone acrylamide, isobutoxymethyl acrylamide, N,N'-dimethyl-aminopropyl acrylamide, N,N-dimethyl acrylamide, N,N-diethyl acrylamide, and t-octylacrylamide; vinyl compounds such as N-vinylpyrrolidone and N-vinylcaprolactam; and acid esters such as maleates and fumarates. Regarding the long-chain and short-chain alkyl acrylates listed above, short-chain alkyl acrylates are alkyl groups with six or fewer carbon atoms, while long-chain alkyl acrylates are alkyl groups with seven or more carbon atoms.

[0204] Representative radiation-curable ethylenically unsaturated monomers include alkoxylated monomers having one or more acrylate or methacrylate groups. Alkoxylated monomers include one or more alkoxylene groups, where the alkoxylene group has the form -OR- and R is a linear or branched hydrocarbon. Examples of alkoxylene groups include ethoxylene (-O-CH2-CH2-), n-propoxylene (-O-CH2-CH2-CH2-), isopropoxylene (-O-CH2-CH(CH3)-), and the like. As used herein, the degree of alkoxylation refers to the number of alkoxylene groups in a monomer. In one embodiment, the alkoxylene groups are consecutively linked in the monomer.

[0205] As used herein, the degree of alkoxylation is the number of alkoxylene groups in one molecule of the monomer divided by the number of acrylate and methacrylate groups. In the case of a monofunctional alkoxylated monomer, the degree of alkoxylation corresponds to the number of alkoxylene groups in one molecule of the monomer. In a preferred embodiment, the alkoxylene groups in the monofunctional alkoxylated monomer are linked consecutively. In the case of a difunctional alkoxylated monomer, the degree of alkoxylation corresponds to half the number of alkoxylene groups in one molecule of the monomer. In a preferred embodiment, the alkoxylene groups in the difunctional alkoxylated monomer are linked consecutively in each of two groups, the two groups being separated by a chemical bond, and each group containing half or approximately half the number of alkoxylene groups in the molecule. In the case of a trifunctional alkoxylated monomer, the degree of alkoxylation corresponds to one-third of the number of alkoxylene groups in one molecule of the monomer. In a preferred embodiment, the alkoxylene groups in the trifunctional alkoxylated monomer are linked in three groups in succession, the three groups being separated by chemical bonds, and each group containing one-third or about one-third of the number of alkoxylene groups in the molecule.

[0206] Exemplary polyfunctional ethylenically unsaturated monomers of the curable secondary coating composition include, without limitation, alkoxylated bisphenol-A diacrylates, such as ethoxylated bisphenol-A diacrylate, and alkoxylated trimethylolpropane triacrylates, such as ethoxylated trimethylolpropane triacrylate, where the degree of alkoxylation is 2 or greater, or 4 or greater, or 6 or greater, or less than 16, or less than 12, or less than 8, or less than 5, or in the range of 2 to 16, or in the range of 2 to 12, or in the range of 2 to 8, or in the range of 2 to 4, or in the range of 3 to 12, or in the range of 3 to 8, or in the range of 3 to 5, or in the range of 4 to 12, or in the range of 4 to 10, or in the range of 4 to 8.

[0207] The polyfunctional ethylenically unsaturated monomers of the curable secondary coating composition include, without limitation, alkoxylated bisphenol A diacrylates, such as ethoxylated bisphenol A diacrylate, having a degree of alkoxylation of 2 or greater. The monomeric components of the secondary coating composition may include ethoxylated bisphenol A diacrylates having a degree of ethoxylation of 2 to about 30 (e.g., SR349, SR601, and SR602 available from Sartomer Company, Inc., West Chester, Pennsylvania, and Photomer 4025 and Photomer 4028 available from IGM Resins), or propoxylated bisphenol A diacrylates having a degree of propoxylation of 2 or greater, e.g., ranging from 2 to about 30; ethoxylated trimethylolpropane triacrylates having a propoxylation of 3 or greater, e.g., ranging from 3 to about 30 (e.g., Photomer 4149, IGM Resins, and SR499, Sartomer Company, Inc., West Chester, Pennsylvania). Methylolpropane polyacrylates, with or without alkoxylation, such as Sartomer Company, Inc.; propoxylated-trimethylolpropane triacrylates with a propoxylation degree of 3 or greater, e.g., ranging from 3 to 30 (e.g., Photomer 4072, IGM Resins, and SR492, Sartomer); ditrimethylolpropane tetraacrylate (e.g., Photomer 4355, IGM Resins); alkoxylated glyceryl triacrylates, such as propoxylated glyceryl triacrylates with a propoxylation degree of 3 or greater (e.g., Photomer 4096, IGM Resins, and SR9020, Sartomer); pentaerythritol tetraacrylate (e.g., SR295 available from Sartomer Company, Inc., West Chester, Pennsylvania), ethoxylated pentaerythritol tetraacrylate (e.g., SR494, Sartomer Company, Inc.), and dipentaerythritol pentaacrylate (e.g., Photomer 4399, IGM Resins, and SR399, Sartomer Company, Inc.erythritol polyacrylates, with or without alkoxylation, such as tris-(2-hydroxyethyl)isocyanurate triacrylate (e.g., SR368, Sartomer Company, Inc.) and tris-(2-hydroxyethyl)isocyanurate diacrylate, formed by reacting an appropriately functional isocyanurate with acrylic acid or acryloyl chloride; alcohol polyacrylates, with or without alkoxylation, such as tricyclodecane dimethanol diacrylate (e.g., CD406, Sartomer Company, Inc.) and ethoxylated polyethylene glycol diacrylates having a degree of ethoxylation of 2 or greater, e.g., ranging from about 2 to 30; epoxy acrylates formed by adding acrylates to bisphenol A diglycidyl ether, for example (e.g., Photomer 3016, IGM Resins); as well as mono- and polycyclic aromatic or non-aromatic polyacrylates such as dicyclopentadiene diacrylate and dicyclopentane diacrylate.

[0208] The polyfunctional ethylenically unsaturated monomers of the curable secondary coating composition include ethoxylated bisphenol-A diacrylates having a degree of ethoxylation ranging from 2 to 16 (e.g., SR349, SR601, and SR602 available from Sartomer Company, Inc., West Chester, Pennsylvania, and Photomer 4028 available from IGM Resins), or propoxylated bisphenol-A diacrylates having a degree of propoxylation of 2 or greater, e.g., 2 to 16; alkoxylated trimethylolpropane triacrylates or ethoxylated trimethylolpropane triacrylates having an alkoxylation or ethoxylation degree of 2 or greater, e.g., 2 to 16 or 3 to 10 (e.g., Photomer 4149, IGM Resins, and SR499, Sartomer Company, Inc., West Chester, Pennsylvania). Methylolpropane polyacrylates, with or without alkoxylation, such as propoxylated trimethylolpropane triacrylate (e.g., Photomer 4072, IGM Resins, and SR492, Sartomer), with a degree of propoxylation of 2 or greater, e.g., ranging from 2 to 16; ditrimethylolpropane tetraacrylate (e.g., Photomer 4355, IGM Resins); alkoxylated glyceryl triacrylates, such as propoxylated glyceryl triacrylate (e.g., Photomer 4096, IGM Resins, and SR9020, Sartomer), with a degree of propoxylation of 2 or greater, e.g., ranging from 2 to 16; pentaerythritol tetraacrylate (e.g., SR295 available from Sartomer Company, Inc., West Chester, Pennsylvania), ethoxylated pentaerythritol tetraacrylate (e.g., SR494, Sartomer), Company, Inc.), and dipentaerythritol pentaacrylate (e.g., Photomer 4399, IGM Resins, and SR399, Sartomer Company, Inc.erythritol polyacrylates, with or without alkoxylation, such as tris-(2-hydroxyethyl)isocyanurate triacrylate (e.g., SR368, Sartomer Company, Inc.) and tris-(2-hydroxyethyl)isocyanurate diacrylate, formed by reacting an appropriately functional isocyanurate with acrylic acid or acryloyl chloride; alcohol polyacrylates, with or without alkoxylation, such as tricyclodecane dimethanol diacrylate (e.g., CD406, Sartomer Company, Inc.) and ethoxylated polyethylene glycol diacrylates having a degree of ethoxylation of 2 or greater, e.g., ranging from 2 to 16; epoxy acrylates formed by adding acrylates to bisphenol A diglycidyl ether, for example (e.g., Photomer 3016, IGM Resins); and mono- and polycyclic aromatic or non-aromatic polyacrylates such as dicyclopentadiene diacrylate and dicyclopentane diacrylate.

[0209] In some embodiments, the curable secondary coating composition comprises greater than 2.0%, or greater than 5.0%, or greater than 7.5%, or greater than 10%, or greater than 15%, or greater than 20%, or in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight of a multifunctional monomer having three or more curable functional groups. In preferred embodiments, each of the three or more curable functional groups is an acrylate group.

[0210] In some embodiments, the curable secondary coating composition comprises greater than 2.0 wt.%, or greater than 5.0 wt.%, or greater than 7.5 wt.%, or greater than 10 wt.%, or greater than 15 wt.%, or greater than 20 wt.%, or in the range of 2.0 wt.% to 25 wt.%, or in the range of 5.0 wt.% to 20 wt.%, or in the range of 8.0 wt.% to 15 wt.%. In a preferred embodiment, the trifunctional monomer is a triacrylate monomer.

[0211] In some embodiments, the curable secondary coating composition comprises a difunctional monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight, and further comprises a trifunctional monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. In preferred embodiments, the difunctional monomer is a diacrylate monomer and the trifunctional monomer is a triacrylate monomer. Preferred diacrylate monomers include alkoxylated bisphenol-A diacrylate. Preferred triacrylate monomers include alkoxylated trimethylolpropane triacrylate and isocyanurate triacrylate. Preferably, the curable secondary coating composition does not include alkoxylated bisphenol-A diacrylates having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0212] In some embodiments, the curable secondary coating composition is free of monofunctional monomers, contains a difunctional monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight, and further contains a trifunctional monomer in an amount ranging from 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. In preferred embodiments, the difunctional monomer is a diacrylate monomer and the trifunctional monomer is a triacrylate monomer. Preferred diacrylate monomers include alkoxylated bisphenol-A diacrylate. Preferred triacrylate monomers include alkoxylated trimethylolpropane triacrylate and isocyanurate triacrylate. Preferably, the curable secondary coating composition does not include alkoxylated bisphenol-A diacrylates having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0213] In some embodiments, the curable secondary coating composition comprises two or more difunctional monomers in a combined amount greater than 70% by weight, or greater than 75% by weight, or greater than 80% by weight, or greater than 85% by weight, or in the range of 70% to 95% by weight, or in the range of 75% to 90% by weight, and further comprises a trifunctional monomer in an amount ranging from 2.0% to 25% by weight, or from 5.0% to 20% by weight, or in the range of 8.0% to 15% by weight. In preferred embodiments, the difunctional monomer is a diacrylate monomer and the trifunctional monomer is a triacrylate monomer. Preferred diacrylate monomers include alkoxylated bisphenol-A diacrylate. Preferred triacrylate monomers include alkoxylated trimethylolpropane triacrylate and isocyanurate triacrylate. Preferably, the curable secondary coating composition does not include alkoxylated bisphenol-A diacrylates having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0214] In some embodiments, the curable secondary coating composition is free of monofunctional monomers, contains two or more difunctional monomers in a combined amount greater than 70% by weight, or greater than 75% by weight, or greater than 80% by weight, or greater than 85% by weight, or in the range of 70% to 95% by weight, or in the range of 75% to 90% by weight, and further contains a trifunctional monomer in an amount ranging from 2.0% to 25% by weight, or from 5.0% to 20% by weight, or in the range of 8.0% to 15% by weight. In preferred embodiments, the difunctional monomer is a diacrylate monomer and the trifunctional monomer is a triacrylate monomer. Preferred diacrylate monomers include alkoxylated bisphenol-A diacrylate. Preferred triacrylate monomers include alkoxylated trimethylolpropane triacrylate and isocyanurate triacrylate. Preferably, the curable secondary coating composition does not include alkoxylated bisphenol-A diacrylates having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0215] In some embodiments, the curable secondary coating composition comprises two or more difunctional monomers in a combined amount greater than 70% by weight, or greater than 75% by weight, or greater than 80% by weight, or greater than 85% by weight, or in the range of 70% to 95% by weight, or in the range of 75% to 90% by weight, and further comprises two or more trifunctional monomers in a combined amount greater than 2.0% to 25% by weight, or in the range of 5.0% to 20% by weight, or in the range of 8.0% to 15% by weight. In preferred embodiments, each of the two or more difunctional monomers is a diacrylate monomer and each of the two or more trifunctional monomers is a triacrylate monomer. Preferred diacrylate monomers include alkoxylated bisphenol-A diacrylate. Preferred triacrylate monomers include alkoxylated trimethylolpropane triacrylate and isocyanurate triacrylate. Preferably, the curable secondary coating composition does not include alkoxylated bisphenol-A diacrylates having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0216] In some embodiments, the curable secondary coating composition is free of monofunctional monomers, contains two or more difunctional monomers in a combined amount greater than 70% by weight, or greater than 75% by weight, or greater than 80% by weight, or greater than 85% by weight, or in the range of 70% to 95% by weight, or in the range of 75% to 90% by weight, and further contains two or more trifunctional monomers in a combined amount greater than 2.0% to 25% by weight, or in the range of 5.0% to 20% by weight, or in the range of 8.0% to 15% by weight. In preferred embodiments, each of the difunctional monomers is a diacrylate monomer and each of the trifunctional monomers is a triacrylate monomer. Preferred diacrylate monomers include alkoxylated bisphenol-A diacrylate. Preferred triacrylate monomers include alkoxylated trimethylolpropane triacrylate and isocyanurate triacrylate. Preferably, the curable secondary coating composition does not include alkoxylated bisphenol-A diacrylates having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0217] A preferred difunctional monomer is alkoxylated bisphenol-A diacrylate, which has the general formula (XIII):

[0218] [ka]

[0219] wherein R1 and R2 are alkylene groups, R1-O and R2-O are alkoxylene groups, and R3 is H. Any two of the groups R1, R2, and R3 are the same or different. In one embodiment, the groups R1 and R2 are the same. The number of carbon atoms in each of the groups R1 and R2 ranges from 1 to 8, or from 2 to 6, or from 2 to 4. The degree of alkoxylation is 1 / 2(x+y). The values ​​of x and y are the same or different. In one embodiment, x and y are the same.

[0220] A preferred trifunctional monomer is alkoxylated trimethylolpropane triacrylate, which has the general formula (XIV):

[0221] [ka]

[0222] wherein R1 and R2 are alkylene groups, and O-R1, O-R2, and O-R3 are alkoxylene groups. Any two of the groups R1, R2, and R3 are the same or different. In one embodiment, the groups R1, R2, and R3 are the same. The number of carbon atoms in each of the groups R1, R2, and R3 ranges from 1 to 8, or from 2 to 6, or from 2 to 4. The degree of alkoxylation is 1 / 3(x+y+z). Any two values ​​of x, y, and z are the same or different. In one embodiment, x, y, and Z are the same.

[0223] Another preferred trifunctional monomer is tris[(acryloyloxy)alkyl]isocyanurate. Tris[(acryloyloxy)alkyl]isocyanurate is also called tris[n-hydroxyalkyl]isocyanurate triacrylate. A representative tris[(acryloyloxy)alkyl]isocyanurate is tris[2-hydroxyethyl]isocyanurate triacrylate, which is represented by the general formula (XV):

[0224] [ka]

[0225] In formula (III), an ethylene bond (-CH2-CH2-) connects each acryloyloxy group to the nitrogen atom of the isocyanurate ring. In other embodiments of tris[(acryloyloxy)alkyl]isocyanurate, an alkylene bond other than ethylene connects the acryloyloxy group to the nitrogen atom of the isocyanurate ring. Any two of the three alkylene bonds are the same or different. In one embodiment, all three alkylene bonds are the same. The number of carbon atoms in each of the alkylene bonds ranges from 1 to 8, or from 2 to 6, or from 2 to 4.

[0226] In one embodiment, the curable Secondary Coating composition comprises an alkoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight, and further comprises an alkoxylated trimethylolpropane triacrylate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable Secondary Coating composition does not comprise an alkoxylated bisphenol-A diacrylate having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0227] In one embodiment, the curable Secondary Coating composition comprises an alkoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight, and further comprises an ethoxylated trimethylolpropane triacrylate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable Secondary Coating composition does not comprise an alkoxylated bisphenol-A diacrylate having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0228] In one embodiment, the curable Secondary Coating composition comprises an ethoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight, and further comprises an alkoxylated trimethylolpropane triacrylate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable Secondary Coating composition does not comprise an alkoxylated bisphenol-A diacrylate having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0229] In one embodiment, the curable Secondary Coating composition comprises an ethoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight, and further comprises an ethoxylated trimethylolpropane triacrylate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable Secondary Coating composition does not comprise an alkoxylated bisphenol-A diacrylate having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0230] In one embodiment, the curable Secondary Coating composition comprises an alkoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight, and further comprises a tris[(acryloyloxy)alkyl]isocyanurate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable Secondary Coating composition does not comprise an alkoxylated bisphenol-A diacrylate having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0231] In one embodiment, the curable Secondary Coating composition comprises an ethoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight, and further comprises a tris[(acryloyloxy)alkyl]isocyanurate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable Secondary Coating composition does not comprise an alkoxylated bisphenol-A diacrylate having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0232] In one embodiment, the curable Secondary Coating composition comprises an alkoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight, and further comprises tris(2-hydroxyethyl)isocyanurate triacrylate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable Secondary Coating composition does not comprise an alkoxylated bisphenol-A diacrylate having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0233] In one embodiment, the curable Secondary Coating composition comprises an ethoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight, and further comprises tris(2-hydroxyethyl)isocyanurate triacrylate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable Secondary Coating composition does not comprise an alkoxylated bisphenol-A diacrylate having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0234] In one embodiment, the curable Secondary Coating composition comprises bisphenol-A epoxy diacrylate monomer in an amount greater than 5.0%, or greater than 10%, or greater than 15%, or in the range of 5.0% to 20%, or in the range of 8% to 17%, or in the range of 10% to 15% by weight; and further comprises alkoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight; and further comprises alkoxylated trimethylolpropane triacrylate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable secondary coating composition does not include alkoxylated bisphenol-A diacrylates having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0235] In one embodiment, the curable Secondary Coating composition comprises bisphenol-A epoxy diacrylate monomer in an amount greater than 5.0%, or greater than 10%, or greater than 15%, or in the range of 5.0% to 20%, or in the range of 8% to 17%, or in the range of 10% to 15% by weight; and further comprises alkoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight; and further comprises ethoxylated trimethylolpropane triacrylate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable secondary coating composition does not include alkoxylated bisphenol-A diacrylates having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0236] In one embodiment, the curable Secondary Coating composition comprises bisphenol-A epoxy diacrylate monomer in an amount greater than 5.0%, or greater than 10%, or greater than 15%, or in the range of 5.0% to 20%, or in the range of 8% to 17%, or in the range of 10% to 15% by weight; and further comprises ethoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight; and further comprises alkoxylated trimethylolpropane triacrylate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable secondary coating composition does not include alkoxylated bisphenol-A diacrylates having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0237] In one embodiment, the curable secondary coating composition comprises bisphenol-A epoxy diacrylate monomer in an amount greater than 5.0%, or greater than 10%, or greater than 15%, or in the range of 5.0% to 20%, or in the range of 8% to 17%, or in the range of 10% to 15% by weight; and further comprises ethoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight; and further comprises ethoxylated trimethylolpropane triacrylate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable secondary coating composition does not include alkoxylated bisphenol-A diacrylates having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0238] In one embodiment, the curable secondary coating composition comprises bisphenol-A epoxy diacrylate monomer in an amount greater than 5.0%, or greater than 10%, or greater than 15%, or in the range of 5.0% to 20%, or in the range of 8% to 17%, or in the range of 10% to 15% by weight; and further comprises alkoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight; and further comprises tris[(acryloyloxy)alkyl]isocyanurate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable secondary coating composition does not include alkoxylated bisphenol-A diacrylates having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0239] In one embodiment, the curable secondary coating composition comprises bisphenol-A epoxy diacrylate monomer in an amount greater than 5.0%, or greater than 10%, or greater than 15%, or in the range of 5.0% to 20%, or in the range of 8% to 17%, or in the range of 10% to 15% by weight; and further comprises ethoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight; and further comprises tris[(acryloyloxy)alkyl]isocyanurate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable secondary coating composition does not include alkoxylated bisphenol-A diacrylates having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0240] In one embodiment, the curable Secondary Coating composition comprises bisphenol-A epoxy diacrylate monomer in an amount greater than 5.0%, or greater than 10%, or greater than 15%, or in the range of 5.0% to 20%, or in the range of 8% to 17%, or in the range of 10% to 15% by weight; and further comprises alkoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight; and further comprises tris(2-hydroxyethyl)isocyanurate triacrylate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable secondary coating composition does not include alkoxylated bisphenol-A diacrylates having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0241] In one embodiment, the curable Secondary Coating composition comprises bisphenol-A epoxy diacrylate monomer in an amount greater than 5.0%, or greater than 10%, or greater than 15%, or in the range of 5.0% to 20%, or in the range of 8% to 17%, or in the range of 10% to 15% by weight; and further comprises ethoxylated bisphenol-A diacrylate monomer in an amount greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or in the range of 55% to 80%, or in the range of 60% to 75% by weight; and further comprises tris(2-hydroxyethyl)isocyanurate triacrylate monomer in an amount in the range of 2.0% to 25%, or in the range of 5.0% to 20%, or in the range of 8.0% to 15% by weight. Preferably, the curable secondary coating composition does not include alkoxylated bisphenol-A diacrylates having a degree of alkoxylation greater than 17, or greater than 20, or greater than 25, or in the range of 15 to 40, or in the range of 20 to 35.

[0242] Preferably, the optional oligomer present in the radiation-curable Secondary Coating composition is a compound having a urethane linkage. In one embodiment, the optional oligomer is a reaction product of a polyol compound, a diisocyanate compound, and a hydroxy-functional acrylate compound. Reaction of the polyol compound with the diisocyanate compound provides a urethane linkage, and the hydroxy-functional acrylate compound reacts with the isocyanate group to provide a terminal acrylate group. If present, the total oligomer content in the radiation-curable Secondary Coating composition is less than 3.0% by weight, or less than 2.0% by weight, or less than 1.0% by weight, or in the range of 0% to 3.0% by weight, or in the range of 0.1% to 3.0% by weight, or in the range of 0.2% to 2.0% by weight, or in the range of 0.3% to 1.0% by weight. In one embodiment, the radiation-curable Secondary Coating composition is oligomer-free.

[0243] One optional group of oligomers is ethylenically unsaturated oligomers. If included, suitable oligomers may be monofunctional, polyfunctional, or a combination of monofunctional and polyfunctional oligomers. The oligomeric component, if present, may include aliphatic and aromatic urethane (meth)acrylate oligomers, urea (meth)acrylate oligomers, polyester and polyether (meth)acrylate oligomers, acrylated acrylic oligomers, polybutadiene (meth)acrylate oligomers, polycarbonate (meth)acrylate oligomers, and melamine (meth)acrylate oligomers, or combinations thereof. The curable secondary coating composition may be free of urethane groups, urethane acrylate compounds, urethane oligomers, or urethane acrylate oligomers.

[0244] The optional oligomeric component of the curable secondary coating composition may include a difunctional oligomer. The difunctional oligomer has the following formula (XVI):

[0245] [ka]

[0246] wherein F1 can independently be a reactive functional group such as an acrylate, methacrylate, acrylamide, N-vinylamide, styrene, vinyl ether, vinyl ester, or other functional group known in the art; R8 can independently be —(CH2) 2~12 -O-, -((CH2) 2~4 -O) n -, -(CH2) 2~12 -O-((CH2) 2~4 -O) n -, -(CH2) 2~12 -O-(CO-(CH2) 2~5 -O) n - or -(CH2) 2~12 -O-(CO-(CH2) 2~5 -NH) n-, where n is an integer from 1 to 30, inclusive, for example, from 1 to 10; R9 is a polyether, polyester, polycarbonate, polyamide, polyurethane, polyurea, or a combination thereof; and m is an integer from 1 to 10, inclusive, for example, from 1 to 5. In the structure of formula (XVI), the urethane moiety may be the residue formed from the reaction of a diisocyanate with R9 and / or R8. The term "independently" is used herein to indicate that each F1 may be different from another F1, and the same is true for each R8.

[0247] The optional oligomeric component of the curable coating composition may include a multifunctional oligomer having formula (XVII), formula (XVIII), or formula (XIX) shown below:

[0248] [ka]

[0249] [ka]

[0250] [ka]

[0251] wherein F2 may independently represent 1 to 3 functional groups such as acrylate, methacrylate, acrylamide, N-vinylamide, styrene, vinyl ether, vinyl ester, or other functional groups known in the art; and R8 may have a structure according to the formula: 2~12 -O-, -((CH2) 2~4 -O) n -, -(CH2) 2~12 -O-((CH2) 2~4 -O) n -, -(CH2) 2~12 -O-(CO-(CH2) 2~5 -O) n- or -(CH2) 2~12 -O-(CO-(CH2) 2~5 -NH) n where n is an integer from 1 to 10, inclusive, for example, from 1 to 5; R9 is a polyether, polyester, polycarbonate, polyamide, polyurethane, polyurea, or a combination thereof; x is an integer from 1 to 10, inclusive, for example, from 2 to 5; and m is an integer from 1 to 10, inclusive, for example, from 1 to 5. In the structure of formula (XVII) or (XIX), the multiurethane group can be the residue formed from the reaction of a multiisocyanate with R9. Similarly, the urethane group in the structure of formula (XVIII) can be the reaction product formed after the attachment of a diisocyanate to R9 and / or R8.

[0252] Urethane oligomers may be prepared by reacting aliphatic or aromatic diisocyanates with dihydric polyethers or polyesters, most typically polyoxyalkylene glycols such as polyethylene glycol. Moisture-resistant oligomers may be synthesized in a similar manner, except that predominantly saturated, predominantly nonpolar aliphatic diols are preferred, and polar polyether or polyester glycols are avoided. These diols may contain alkanes or alkylene glycols of about 2 to 250 carbon atoms, which may be substantially free of ether or ester groups.

[0253] Polyurea components may be included in oligomers prepared by these methods, for example, by substituting diamines or polyamines for diols or polyols during synthesis.

[0254] The curable Secondary Coating composition also includes a photoinitiator and optionally includes additives such as antioxidants, optical brighteners, amine synergists, tackifiers, catalysts, carriers or surfactants, and stabilizers, as described above with respect to the curable Primary Coating composition.

[0255] The curable secondary coating composition includes a single photoinitiator or a combination of two or more photoinitiators, and the total photoinitiator content of the curable secondary coating composition is up to about 10% by weight, or between about 0.5% and about 6% by weight.

[0256] An exemplary antioxidant is thiodiethylenebis[3-(3,5-di-tert-butyl)-4-hydroxy-phenyl)propionate] (e.g., IRGANOX 1035, available from BASF). In some embodiments, the antioxidant is present in the curable Secondary Coating composition in an amount greater than 0.25%, or greater than 0.50%, or greater than 0.75%, or greater than 1.0%, or in an amount ranging from 0.25% to 3.0%, or in an amount ranging from 0.50% to 2.0%, or in an amount ranging from 0.75% to 1.5% by weight.

[0257] Representative optical brighteners include TINOPAL OB (available from BASF); Blankophor KLA (available from Bayer); bisbenzoxazole compounds; phenylcoumarin compounds; and bis(styryl)biphenyl compounds. In one embodiment, the optical brightener is present in the curable Secondary Coating composition at a concentration of 0.005% to 0.3% by weight.

[0258] Representative amine synergists include triethanolamine, 1,4-diazabicyclo[2.2.2]octane (DABCO), triethylamine, and methyldiethanolamine. In certain embodiments, the amine synergist is present in a concentration of 0.02% to 0.5% by weight.

[0259] Secondary Coating - Properties. Relevant properties of secondary coatings include radius, thickness, Young's modulus, tear strength, yield strength, elongation at yield, and puncture resistance.

[0260] The radius r6 of the secondary coating is 100.0 μm or less, or 95.0 μm or less, or 90.0 μm or less, or 85.0 μm or less, or 80.0 μm or less, or in the range of 77.5 μm to 100.0 μm, or in the range of 77.5 μm to 97.5 μm, or in the range of 77.5 μm to 95.0 μm, or in the range of 77.5 μm to 92.5 μm, or in the range of 77.5 μm to 90.0 μm, or in the range of 80.0 μm to 100.0 μm. or in the range of 80.0 μm to 97.5 μm, or in the range of 80.0 μm to 95.0 μm, or in the range of 80.0 μm to 92.5 μm, or in the range of 80.0 μm to 90.0 μm, or in the range of 82.5 μm to 100.0 μm, or in the range of 82.5 μm to 97.5 μm, or in the range of 82.5 μm to 95.0 μm, or in the range of 82.5 μm to 92.5 μm, or in the range of 82.5 μm to 90.0 μm.

[0261] To facilitate the reduction in the optical fiber diameter, it is preferable to minimize the thickness r6-r5 of the secondary coating. The thickness r6-r5 of the secondary coating may be in the range of 15.0 μm to 32.5 μm, or in the range of 17.5 μm to 32.5 μm, or in the range of 20.0 μm to 32.5 μm, or in the range of 22.5 μm to 32.5 μm, or in the range of 25.0 μm to 32.5 μm, or in the range of 27.5 μm to 32.5 μm, or in the range of 15.0 μm to 30.0 μm, or in the range of 17.5 μm to 32.5 μm. In the range of 5 μm to 30.0 μm, or in the range of 20.0 μm to 30.0 μm, or in the range of 22.5 μm to 30.0 μm, or in the range of 25.0 μm to 30.0 μm, or in the range of 15.0 μm to 27.5 μm, or in the range of 17.5 μm to 27.5 μm, or in the range of 20.0 μm to 27.5 μm, or in the range of 15.0 μm to 25.0 μm.

[0262] To promote puncture resistance and high protection, the secondary coating preferably has a high Young's modulus, such as 1600 MPa or greater, or 1800 MPa or greater, or 2000 MPa or greater, or 2200 MPa or greater, or in the range of 1600 MPa to 2800 MPa, or in the range of 1800 MPa to 2600 MPa.

[0263] Fiber Draw Process. In a continuous optical fiber manufacturing process, a glass fiber is drawn from a heated preform to a target diameter (typically 125 μm). In some embodiments, the diameter of the glass fiber is 125 micrometers. In some other embodiments, the diameter of the glass fiber is less than 110 μm. In still other embodiments, the diameter of the glass fiber is less than 100 micrometers. The glass fiber is then cooled and directed to a coating system that applies a liquid primary coating composition to the glass fiber. After the liquid primary coating composition is applied to the glass fiber, there are two process options. In the first process option (wet-on-dry process), the liquid primary coating composition is cured to form a solidified primary coating, a liquid secondary coating composition is applied to the cured primary coating, and the liquid secondary coating composition is cured to form a solidified secondary coating. In the second process option (wet-on-wet process), a liquid secondary coating composition is applied to a liquid primary coating composition and both liquid coating compositions are cured simultaneously to provide solidified primary and secondary coatings. After the fiber exits the coating system, it is collected and stored at room temperature. Collecting the fiber typically entails winding the fiber onto a spool and storing the spool.

[0264] In some processes, the coating system applies a tertiary coating composition to the secondary coating and cures the tertiary coating composition to form a solidified tertiary coating. Typically, the tertiary coating is an ink layer used to mark the fiber for identification purposes, contains a pigment, and otherwise has a similar composition to the secondary coating. The tertiary coating is applied to the secondary coating and cured. The secondary coating is typically cured at the time of application of the tertiary coating. The primary, secondary, and tertiary coating compositions can be applied and cured in a common continuous manufacturing process. Alternatively, the primary and secondary coating compositions are applied and cured in a common continuous manufacturing process, the coated fiber is collected, and the tertiary coating composition is applied and cured in a separate, offline process to form the tertiary coating.

[0265] The wavelength of the curing radiation can be infrared, visible, or ultraviolet (UV). Exemplary wavelengths include those in the range of 250 nm to 1000 nm, or 250 nm to 700 nm, or 250 nm to 450 nm, or 275 nm to 425 nm, or 300 nm to 400 nm, or 320 nm to 390 nm, or 330 nm to 380 nm, or 340 nm to 370 nm. Curing can be accomplished with light sources including lamp sources (e.g., Hg lamps), LED sources (e.g., UV LEDs, visible LEDs, or infrared LEDs), or laser sources.

[0266] Each of the primary, secondary, and tertiary compositions can be cured using any of the wavelengths and light sources listed above. The same wavelength or light source can be used to cure each of the primary, secondary, and tertiary compositions, or different wavelengths and / or different light sources can be used to cure the primary, secondary, and tertiary compositions. Curing of the primary, secondary, and tertiary compositions can be achieved using a single wavelength or a combination of two or more wavelengths.

[0267] To improve process efficiency, it is desirable to increase the draw speed of the fiber along the process path extending from the preform to the collection point. However, as the draw speed increases, the cure rate of the coating composition must also increase. The coating compositions disclosed herein are compatible with fiber draw processes operating at draw speeds greater than 35 m / s, or greater than 40 m / s, or greater than 45 m / s, or greater than 50 m / s, or greater than 55 m / s, or greater than 60 m / s, or greater than 65 m / s, or greater than 70 m / s.

[0268] The present disclosure extends to optical fibers coated with the cured product of a coating composition, the optical fiber comprising a glass waveguide having a higher refractive index glass core region surrounded by a lower refractive index glass cladding region. The coating formed as the cured product of the coating composition of the present disclosure surrounds and is in direct contact with the glass cladding. The cured product of the coating composition of the present disclosure functions as a primary, secondary, or tertiary coating for the fiber. [Example]

[0269] Example - Primary Coating The following examples illustrate the preparation of representative Primary Coatings, and the measurement of selected properties of the representative Primary Coatings are also described.

[0270] Primary Coating - Oligomer. A representative primary coating composition included oligomers. For illustrative purposes, H12MDI (4,4'-methylenebis(cyclohexyl isocyanate)), PPG4000 (M n The preparation of an exemplary oligomer from propylene glycol (polypropylene glycol) with a molecular weight of approximately 4000 g / mol) and HEA (2-hydroxyethyl acrylate) is described. All reagents were used as supplied by the manufacturer without further purification. H12MDI was obtained from ALDRICH. PPG4000 was obtained from COVESTRO and certified to have an unsaturation level of 0.004 meq / g, as determined by the method described in standard ASTM D4671-16. HEA was obtained from KOWA.

[0271] Six oligomers were obtained by varying the relative amounts of reactants and reaction conditions. Oligomers with different initial molar ratios of components were prepared with reactant molar ratios satisfying the formula H12MDI:HEA:PPG4000 = n:m:p, where n ranged from 3.0 to 4.0, m ranged from 1.5n-3 to 2.5n-5, and p = 2. In the reactions used to form the oligomeric materials, dibutyltin dilaurate was used as the catalyst (at a level of 160 ppm based on the mass of the initial reaction mixture) and 2,6-di-tert-butyl-4-methylphenol (BHT) was used as the inhibitor (at a level of 400 ppm based on the mass of the initial reaction mixture).

[0272] The amounts of reactants used to prepare each of the six oligomers are summarized in Table 1 below. The six oligomers are identified by separate sample numbers 1 through 6. Corresponding sample numbers are used herein to refer to coating compositions containing each of the six oligomers individually and cured films formed therefrom. The corresponding moles used to prepare each of the six samples are listed in Table 2 below. The moles are normalized to set the mole number p of PPG4000 to 2.0.

[0273] [Table 1]

[0274] [Table 2]

[0275] The oligomer was prepared by combining 4,4'-methylenebis(cyclohexyl isocyanate), dibutyltin dilaurate, and 2,6-di-tert-butyl-4-methylphenol in a 500 mL flask at room temperature. The 500 mL flask was equipped with a thermometer, a CaCl2 drying tube, and a stirrer. While continuously stirring the contents of the flask, PPG 4000 was added using an addition funnel over a period of 30 to 40 minutes. During the PPG 4000 addition, the internal temperature of the reaction mixture was monitored, and the introduction of PPG 4000 was controlled to prevent excessive heating (caused by the exothermic nature of the reaction). After the PPG 4000 addition, the reaction mixture was heated in a water bath at approximately 70 to 75°C for approximately 1 to 1.5 hours. At various intervals, samples of the reaction mixture were withdrawn for analysis by infrared spectroscopy (FTIR) to determine the concentration of unreacted isocyanate groups, thereby monitoring the progress of the reaction. The concentration of unreacted isocyanate groups is 2265 cm -1 The reaction mixture was evaluated based on the intensity of the characteristic isocyanate stretching mode near the reaction site. The flask was removed from the water bath and its contents were allowed to cool to below 65°C. Supplemental HEA was added dropwise over 2-5 minutes using an addition funnel. After the supplemental HEA was added, the flask was returned to the water bath and its contents were reheated to approximately 70-75°C for approximately 1-1.5 hours. FTIR analysis was performed on the reaction mixture to assess the presence of isocyanate groups, and this process was repeated until enough supplemental HEA had been added to completely react any unreacted isocyanate groups. The reaction was considered complete when no appreciable isocyanate stretching intensity was detected in the FTIR measurement. The amount of HEA listed in Table 1 includes the initial amount of HEA in the composition and any supplemental HEA needed to quench unreacted isocyanate groups.

[0276] The concentration (wt%) of the diadduct in each oligomer was determined by gel permeation chromatography (GPC). A Waters Alliance 2690 GPC system was used to determine the concentration of the diadduct. The mobile phase was THF. The system was equipped with three Polymer Labs columns in series. Each column was 300 mm long and had an internal diameter of 7.5 mm. Two of the columns (columns 1 and 2) were packed with PLgel Mixed D stationary phase (polystyrene divinylbenzene copolymer, average particle size = 5 μm, specified molecular weight range = 200 g / mol to 400,000 g / mol) sold by Agilent Technologies under part number PL1110-6504. The third column (column 3) was sold by Agilent Technologies under part number PL1110-6520 and packed with PLgel 100A stationary phase (polystyrene divinylbenzene copolymer, average particle size = 5 μm, specified molecular weight range = up to 4,000 g / mol). These columns were calibrated with polystyrene standards ranging from 162 g / mol to 6,980,000 g / mol using the EasiCal PS-1&2 Polymer Calibration Kit (Agilent Technologies part numbers PL2010-505 and PL2010-0601). The GPC instrument was operated under the following conditions: flow rate = 1.0 mL / min, column temperature = 40 °C, injection volume = 100 μL, and run time = 35 min (isocratic conditions). The detector was a Waters Alliance 2410 differential refractometer operated at 40 °C and sensitivity level 4. Samples were injected in duplicate, along with a THF + 0.05% toluene blank.

[0277] The amount of diadduct (wt%) in the oligomer was quantified using the GPC system and technique described above. Calibration curves were obtained using standard solutions containing known amounts of diadduct compounds (HEA-H12MDI-HEA) in THF. Standard solutions with adduct concentrations of 115.2 μg / g, 462.6 μg / g, 825.1 μg / g, and 4180 μg / g were prepared. (As used herein, the unit "μg / g" refers to μg of diadduct per gram of total solution (diadduct + THF).) Two 100 μL aliquots of each diadduct standard solution were injected onto the column to obtain calibration curves. The retention time of the diadduct was approximately 23 minutes, and the area of ​​the diadduct GPC peak was measured and correlated to the diadduct concentration. A linear correlation of the peak area as a function of diadduct concentration was obtained (correlation coefficient (R 2 )=0.999564).

[0278] The concentration of the di-adduct in the oligomer was determined using the calibration. Samples were prepared by diluting approximately 0.10 g of oligomeric material in THF to obtain approximately 1.5 g of test solution. The test solution was run on a GPC instrument to determine the peak area associated with the di-adduct. The di-adduct concentration in μg / g was obtained from the peak area and the calibration curve and converted to wt % by multiplying by the mass (g) of the test solution and dividing by the mass of the sample of oligomeric material before dilution with THF. The wt % of the di-adduct present in each of the six oligomers prepared in this example is reported in Table 2.

[0279] By varying the relative molar ratios of H12MDI, HEA, and PPG4000, illustrative oligomers contain polyetherurethane compounds of the type shown in formula (IV) above and increasing concentrations of diaddition compounds of the type shown in formula (V) above.

[0280] Primary Coating - Compositions. The oligomers corresponding to Samples 1-6 were separately combined with other ingredients to form a series of six exemplary primary coating compositions. The amount of each component in the coating compositions is shown in Table 3 below. The Table 3 listing for an oligomer includes the total amount of polyether urethane acrylate compound and di-addition compound present in the oligomer. A separate coating composition was made for each of the six exemplary oligomers corresponding to Samples 1-6. The amount of di-addition compound in the oligomeric material corresponded to the amount listed in Table 2.

[0281] [Table 3]

[0282] Sartomer SR504 is ethoxylated (4) nonylphenol acrylate (available from Sartomer). V-CAP / RC is N-vinylcaprolactam (available from ISP Technologies). TPO is (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (available from BASF under the trade name Lucirin) and functions as a photoinitiator. Irganox 1035 is thiodiethylene bis[3-(3,5-di-tert-butyl)-4-hydroxyphenyl)propionate] (available from BASF) and functions as an antioxidant. The adhesion promoters were 3-acryloxypropyltrimethoxysilane (available from Gelest) and 3-mercaptopropyltrimethoxysilane (available from Aldrich). 3-acryloxypropyltrimethoxysilane was used for samples 1, 3, and 5. 3-mercaptopropyltrimethoxysilane was used for samples 2, 4, and 6. Tetrathiol is a catalyst inhibitor.

[0283] Each of the coating compositions in Table 3 was compounded using a high-speed mixer in a suitable container heated to 60°C with a heating band or heating mantle. In each case, the components were weighed into the container using a balance and mixed until the solid components were completely dissolved and the mixture appeared homogeneous. The oligomer and monomer (SR504, NVC) of each composition were blended together at 55-60°C for at least 10 minutes. Next, the photoinitiator, antioxidant, and catalyst inhibitor were added, and blending continued for 1 hour while maintaining the temperature at 55-60°C. Finally, the adhesion promoter was added, and blending continued for 30 minutes at 55-60°C to form the coating composition.

[0284] Primary Coating - Properties - Tensile Properties. Tensile properties (Young's modulus, tensile strength at yield, and elongation at yield) were measured for films formed by curing six coating compositions. A separate film was formed from each coating composition. A wet film of the coating composition was formed on silicone release paper using a drawdown box with a gap thickness of approximately 0.005 inches (approximately 0.13 mm). The wet film was cured at 1.2 J / cm2 using a Fusion Systems UV curing unit equipped with a 600 W / in2 (approximately 236 W / cm2) D-type bulb (50% power and a belt speed of approximately 12 ft / min2). 2 (measured with a Light Bug model IL490 from International Light over a wavelength range of 225 to 424 nm) to produce a cured coating in the form of a film. The thickness of the cured film was between about 0.0030 inches (about 0.076 mm) and 0.0035 inches (about 0.089 mm).

[0285] The membranes were aged for at least 16 hours (23°C, 50% relative humidity) before testing. Membrane specimens were cut to dimensions of 12.5 cm x 13 mm using a cutting template and scalpel. Young's modulus, tensile strength at yield, and elongation at yield were measured for the membrane specimens at room temperature (23°C) using an MTS Sintech tensile testing instrument according to the procedures described in ASTM Standard D882-97. Young's modulus is defined as the initial, steepest slope of the stress-strain curve. The membranes were tested with an initial gauge length of 5.1 cm at an extension rate of 2.5 cm / min. The results are shown in Table 4.

[0286] [Table 4]

[0287] Primary Coating - Properties - In Situ Modulus. In situ modulus measurements were completed for Samples 2, 3, and 5 of the primary coating composition. The in situ modulus measurements required forming a primary coating on a 125 μm diameter glass fiber. Each of Samples 2, 3, and 5 was applied separately as a primary coating composition to the glass fiber as it was being drawn. The fiber draw speed was 50 m / s. The primary coating composition was cured using a stack of five LED light sources. Each LED light source was operated at 395 nm and provided 12 W / cm 2 After application and curing of the Primary Coating Compositions, a Secondary Coating Composition was applied to each of the cured Primary Coatings and cured using a UV light source to form a Secondary Coating Layer. The Primary Coating had a thickness of 32.5 μm and the Secondary Coating had a thickness of 26.0 μm.

[0288] The in situ modulus was measured using the following procedure. A 6-inch (approximately 15 cm) sample of fiber was obtained, and a 1-inch (approximately 2.5 cm) portion from the center of the fiber was windowed and wiped with isopropyl alcohol. The windowed fiber was mounted on a sample holder / alignment stage equipped with 10 mm x 5 mm rectangular aluminum tabs used to mount the fiber. The two tabs were oriented horizontally, with the shorter 5 mm sides facing each other and separated by a 5 mm gap. The windowed fiber was placed horizontally on the sample holder across the gap separating the tabs. The coated end of the fiber on one side of the windowed stripped region was positioned over one tab, extending halfway through the 5 mm gap between the tabs. The 1-inch (approximately 2.5 cm) windowed stripped region then extended across the opposite tab across the remaining half of the gap. After alignment, the sample was moved and a small dot of adhesive was applied to the half of each tab closest to the 5 mm gap. The fiber was then returned to its original position, and the alignment stage was raised until the adhesive just touched the fiber. The coating end was then pulled away from the gap through the adhesive until the majority of the 5 mm gap between the tabs was occupied by the stripped window region of the fiber. The portion of the stripped window region remaining on the opposite tab was in contact with the adhesive. The very tip of the coating end remained extending beyond the tab into the gap between the tabs. This portion of the coating end was not embedded in the adhesive and was the subject of in situ modulus measurements. The adhesive was allowed to dry with the fiber sample in this configuration, attaching the fiber to the tabs. After drying, the length of fiber secured to each tab was trimmed to 5 mm. The length of coating embedded in the adhesive, the length of coating not embedded (the portion extending into the gap between the tabs), and the diameter of the primary coating were measured.

[0289] In situ modulus measurements were performed at room temperature (21 °C) for 45 min. -6Tests were performed on a Rheometrics DMTA IV dynamic mechanical testing instrument at a constant strain of 1 / s. The gauge length was 15 mm. The force and length changes were recorded and used to calculate the in-situ modulus of the primary coating. The tab-mounted fiber sample was prepared by removing any epoxy from the tab that would interfere with the 15 mm clamping length of the test fixture to ensure there was no contact between the clamp and the fiber and the sample was directly secured to the clamp. The instrument force was zeroed. The tab with the uncoated end of the fiber attached was then mounted in the lower clamp (measurement probe) of the test fixture, and the tab with the coated end of the fiber attached was mounted in the upper (fixed) clamp of the test fixture. The test was then performed, and the sample was removed once the analysis was complete.

[0290] The in situ modulus of primary coating samples 2, 3, and 5 are listed in Table 5.

[0291] [Table 5]

[0292] Example - Secondary Coating The following examples illustrate the preparation of representative secondary coatings, and the measurement of selected properties of the representative secondary coatings are also described.

[0293] Secondary Coating Compositions. Representative curable secondary coating compositions are listed in Table 6.

[0294] [Table 6]

[0295] SR601 is an ethoxylated (4) bisphenol A diacrylate (monomer). SR602 is an ethoxylated (10) bisphenol A diacrylate (monomer). SR349 is an ethoxylated (2) bisphenol A diacrylate (monomer). SR399 is dipentaerythritol pentaacrylate. SR499 is an ethoxylated (6) trimethylolpropane triacrylate. CD9038 is an ethoxylated (30) bisphenol A diacrylate (monomer). Photomer 3016 is a bisphenol A epoxy diacrylate (monomer). TPO is a photoinitiator. Irgacure 184 is 1-hydroxycyclohexyl phenyl ketone (photoinitiator). Irgacure 1850 is bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide (photoinitiator). Irganox 1035 is thiodiethylenebis(3,5-di-tert-butyl)-4-hydroxyhydrocinnamate (antioxidant). DC190 is a silicone-ethylene oxide / propylene oxide copolymer (slip agent). The concentration unit "pph" refers to the amount relative to the base composition, including all monomers, oligomers, and photoinitiators. For example, for Secondary Coating Composition KA, a concentration of 1.0 pph for DC-190 corresponds to 1 g of DC-190 per 100 g of SR601, CD9038, Photomer 3016, TPO, and Irgacure 184 combined.

[0296] A comparative curable secondary coating composition (A) and three representative curable secondary coating compositions (SB, SC, and SD) are listed in Table 7.

[0297] [Table 7]

[0298] PE210 is bisphenol-A epoxy diacrylate (available from Miwon Specialty Chemical, Korea), M240 is ethoxylated (4) bisphenol-A diacrylate (available from Miwon Specialty Chemical, Korea), M2300 is ethoxylated (30) bisphenol-A diacrylate (available from Miwon Specialty Chemical, Korea), M3130 is ethoxylated (3) trimethylolpropane triacrylate (available from Miwon Specialty Chemical, Korea), TPO (photoinitiator) is (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (available from BASF), Irgacure 184 (photoinitiator) is 1-hydroxycyclohexyl-phenyl ketone (available from BASF), Irganox 1035 (antioxidant) is benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxythiodi-2,1-ethanediyl ester (available from BASF). DC190 (slip agent) is a silicone-ethylene oxide / propylene oxide copolymer (available from Dow Chemical). The concentration unit "pph" refers to the amount relative to the base composition, including all monomers and photoinitiators. For example, for Secondary Coating Composition A, a concentration of 1.0 pph for DC-190 corresponds to 1 gram of DC-190 per 100 grams of the combined total of PE210, M240, M2300, TPO, and Irgacure 184.

[0299] Secondary Coatings - Properties. The Young's modulus, tensile strength at break, and elongation at break of secondary coatings made from representative secondary coating compositions A, KA, KB, KC, KD, SB, SC, and SD were measured.

[0300] Secondary Coatings - Properties - Measurement Techniques The properties of the secondary coatings were determined using the measurement techniques described below.

[0301] Tensile properties.The curable Secondary Coating composition was cured and configured into coated rod samples for measurement of Young's modulus, tensile strength at break, yield strength, and elongation at break. The cured rods were prepared by injecting the curable Secondary Coating composition into Teflon tubing with an inner diameter of about 0.025 inches (about 6.35 mm). The rod samples had a thermal conductivity of about 2.4 J / cm. 2 The secondary coating compositions were cured using a Fusion D bulb at a dose of 1000 kJ / cm² (measured over a wavelength range of 225-424 nm by a Light Bug Model IL390 from International Light). After curing, the Teflon tube was stripped away to provide cured rod samples of the secondary coating composition. The cured rods were conditioned for 18-24 hours at 23°C and 50% relative humidity before testing. Young's modulus, tensile strength at break, yield strength, and elongation at break were measured on defect-free rod samples using a Sintech MTS Tensile Tester with a 51 mm gauge length and a test speed of 250 mm / min. Tensile properties were measured according to ASTM standard D882-97. Properties were determined as the average of at least five samples, with defective samples excluded from the average.

[0302] Puncture resistance of secondary coating. Puncture resistance measurements were performed on samples comprising a glass fiber, a primary coating, and a secondary coating. The diameter of the glass fiber was 125 μm. The primary coating was formed from the reference primary coating composition listed in Table 8 below. Samples with various secondary coatings were prepared as described below. The thicknesses of the primary and secondary coatings were adjusted to vary the cross-sectional area of ​​the secondary coating, as described below. For all samples, the ratio of secondary coating thickness to primary coating thickness was maintained at approximately 0.8.

[0303] Puncture resistance is measured using the Proceedings of the 52 ndMeasurements were made using the technique described in a paper by G. Scott Glaesemann and Donald A. Clark entitled "Quantifying the Puncture Resistance of Optical Fiber Coatings," published at the International Wire & Cable Symposium (pp. 237-245, 2003). A summary of the method is provided here. The method is an indentation technique. A 4-centimeter length of optical fiber was placed on a 3-mm thick glass slide. One end of the optical fiber was attached to a device that allows for controlled rotation of the optical fiber. The optical fiber was examined for transmission at 100x magnification and rotated until the thickness of the secondary coating was equal on both sides of the glass fiber in the direction parallel to the glass slide. In this position, the thickness of the secondary coating was equal on both sides of the glass fiber in the direction parallel to the glass slide. The thickness of the secondary coating above or below the glass fiber, in the direction perpendicular to the glass slide, was different from the thickness of the secondary coating in the direction parallel to the glass slide. One of the thicknesses perpendicular to the glass slide was greater than the thickness parallel to the glass slide, and the other thickness perpendicular to the glass slide was smaller than the thickness parallel to the glass slide. This position of the optical fiber was fixed by taping both ends of the optical fiber to the glass slide. This position was the position of the optical fiber used in the indentation test.

[0304] Indentation was performed using a universal testing machine (Instron Model 5500R or equivalent). An inverted microscope was placed directly beneath the crosshead of the machine. The microscope objective was positioned directly beneath a 75° diamond wedge indenter mounted in the machine. The glass slide with the taped fiber was placed on the microscope stage and positioned directly beneath the indenter, with the width of the indenter's wedge perpendicular to the direction of the fiber. With the optical fiber in place, the diamond wedge was lowered until it made contact with the surface of the secondary coating. The diamond wedge was then pressed into the secondary coating at a rate of 0.1 mm / min, and the load on the secondary coating was measured. The load on the secondary coating was increased as the diamond wedge was pressed deeper into the secondary coating until perforation occurred. At that point, a steep drop in load was observed. The indentation load at which puncture was observed was recorded. The load is reported here in gram force. The experiment was repeated with the same optical fiber orientation to obtain 10 measurement points. These measurement points were averaged to determine the puncture resistance for that orientation. A second set of 10 measurement points was determined by rotating the optical fiber orientation by 180°.

[0305] Microbend. In a wire-mesh coated drum test, the attenuation of light at a wavelength of 1550 nm through a 750 m length of coated fiber was determined at room temperature. Microbend-induced attenuation was determined by the difference between zero-tension and high-tension configurations on the wire-mesh coated drum. Separate measurements were performed for two winding configurations. In the first configuration, the fiber was wound in a zero-tension configuration on an aluminum drum with a smooth surface and a diameter of approximately 400 mm. This zero-tension winding configuration provided a stress-free baseline attenuation of light passing through the fiber. After a sufficient rest period, initial attenuation measurements were performed. In the second winding configuration, the fiber sample was wound around an aluminum drum wrapped in a thin wire mesh. For this setup, the outer surface of the aluminum drum was covered with wire mesh, and the fiber was wrapped around the mesh. The wire mesh was tightly wrapped around the drum without stretching and maintained intact, without holes, dents, tears, or damage. The wire mesh material used for the measurements was made from corrosion-resistant Type 304 stainless steel wire mesh and had the following characteristics: mesh per linear inch: 165 x 165, wire diameter: 0.0019 in (approximately 0.048 mm), opening width: 0.0041 in (approximately 0.10 mm), and % open area: 44.0. A 750 m length of coated fiber was wound onto the wire mesh coating drum at 1 m / s with a winding pitch of 0.050 cm while applying a tension of 80 (±1) grams. Both ends of the fiber were taped to maintain tension and to prevent fiber crossing. The contact points between the wrapped fiber and the wire mesh applied stress to the fiber, and the attenuation of light passing through the wrapped fiber is a measure of the stress-induced (microbend) loss of the fiber. Wire mesh coating drum measurements were taken after a 1-hour rest period. The increase in fiber attenuation (expressed in dB / km) for measurements made on the second configuration (wire mesh coated drum) relative to the first configuration (smooth drum) was determined for each wavelength. An average of three runs was determined for each wavelength. This average is reported as the wire mesh coated drum microbend loss.

[0306] Reference Primary Coating. For in-situ glass transition temperature (Tg) and puncture resistance measurements, the measured specimens included a primary coating between the glass fiber and the secondary coating. The primary coating composition had the formulation given in Table 8, which is typical of commercially available primary coating compositions.

[0307] [Table 8]

[0308] Here, oligomeric materials were prepared as previously described from H12MDI, HEA, and PPG4000 using a molar ratio of n:m:p=3.5:3.0:2.0, SR504 is ethoxylated (4) nonylphenol acrylate (available from Sartomer), NVC is N-vinylcaprolactam (available from Aldrich), TPO (photoinitiator) is (2,4,6-trimethylbenzoyl)-diphenylphosphine oxide (available from BASF), and Irganox 1035 (antioxidant) is benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxythiodi-2,1-ethanediyl ester (available from BASF), 3-acryloxypropyltrimethoxysilane is an adhesion promoter (available from Gelest), and pentaerythritol tetrakis(3-mercaptopropionate) (also known as tetrathiol, available from Aldrich) is a chain transfer agent. The concentration unit "pph" refers to the amount relative to the base composition, including all monomers, oligomers, and photoinitiators. For example, a concentration of 1.0 pph for Irganox 1035 corresponds to 1 gram of Irganox 1035 per 100 grams of the combined oligomeric material, SR504, NVC, and TPO.

[0309] Secondary Coatings - Properties - Tensile Properties. The results of tensile property measurements performed on representative curable Secondary Coating compositions are shown in Table 9.

[0310] [Table 9]

[0311] These results show that the secondary coatings prepared from compositions SB, SC, and SD exhibited higher Young's modulus and higher yield strength than the secondary coating prepared from comparative composition A. The higher values ​​represent an improvement that makes the secondary coatings prepared from the exemplary curable coating compositions disclosed herein suitable for smaller diameter optical fibers. More specifically, the higher values ​​allow for the use of thinner secondary coatings on the optical fiber without sacrificing performance. A thinner secondary coating reduces the overall diameter of the optical fiber, allowing for a larger total number of fibers in a cable of a given cross-sectional area.

[0312] The Young's modulus of the Secondary Coatings prepared as cured products from the exemplary curable Secondary Coating compositions disclosed herein is greater than 1600 MPa, or greater than 1900 MPa, or greater than 2200 MPa, or greater than 2500 MPa, or in the range of 1600 MPa to 2800 MPa, or in the range of 1900 MPa to 2500 MPa.

[0313] The yield strength of Secondary Coatings prepared as cured products from exemplary curable Secondary Coating compositions disclosed herein is greater than 55 MPa, or greater than 60 MPa, or greater than 65 MPa, or greater than 70 MPa, or in the range of 55 MPa to 75 MPa, or in the range of 60 MPa to 70 MPa.

[0314] Secondary Coatings—Properties—Puncture Resistance. The puncture resistance of secondary coatings made from comparative curable secondary coating composition A, a commercially available curable secondary coating composition (CPC6e) from a commercial supplier (DSM Desotech) with a proprietary composition, and curable secondary coating composition SD was determined according to the method described previously. Several fiber samples were prepared with each of the three secondary coatings. Each fiber sample included a 125 μm diameter glass fiber, a primary coating formed from the reference primary coating composition listed in Table 8, and one of three secondary coatings. Samples with various secondary coatings were prepared. The thicknesses of the primary and secondary coatings were adjusted to vary the cross-sectional area of ​​the secondary coating, as shown in FIG. 7. For all samples, the ratio of secondary coating thickness to primary coating thickness was maintained at approximately 0.8.

[0315] To determine the dependence of puncture load on secondary coating thickness, fiber samples with a range of thicknesses were prepared for each secondary coating. One strategy for achieving a higher total number of fibers in a cable is to reduce the thickness of the secondary coating. However, as the thickness of the secondary coating decreases, its performance decreases and its protective function is compromised. Puncture resistance is a measure of the protective function of the secondary coating. Secondary coatings with higher puncture resistance can withstand greater impacts without breaking, providing better protection for the glass fiber.

[0316] The puncture load as a function of cross-sectional area for the three coatings is shown in Figure 7. An approximate linear correlation of puncture load with the cross-sectional area of ​​the secondary coating was observed, and therefore cross-sectional area was chosen as the parameter for reporting puncture load. Lines 72, 74, and 76 show the approximate linear correlation of puncture load to cross-sectional area for the comparative secondary coatings obtained by curing the comparative CPC6e secondary coating composition, the comparative curable secondary coating composition A, and the curable secondary coating composition SD, respectively. The vertical dotted lines indicate the puncture load at 10,000 μm as shown. 2 , 15000μm 2 , and 20,000 μm 2 are given as a guide for ease of viewing at cross-sectional areas.

[0317] The CPC6e Secondary Coating, represented by line 72, corresponds to conventional Secondary Coatings known in the art. Comparative Secondary Coating A, represented by line 74, shows an improvement in puncture load for large cross-sectional areas. However, this improvement decreases with decreasing cross-sectional area. This suggests that the Secondary Coating obtained as the cured product of Comparative Curable Secondary Coating Composition A is unlikely to be suitable for applications with a high count of small diameter fibers. In contrast, line 76 shows a significant increase in puncture load for the Secondary Coating obtained as the cured product of Curable Secondary Coating Composition SD. For example, for 7000 μm 2 At this cross-sectional area, the puncture load of the Secondary Coating obtained from Curable Secondary Coating Composition SD is more than 50% greater than the puncture load of either of the other two Secondary Coatings.

[0318] 10,000 μm 2 The puncture load of a Secondary Coating formed as the cured product of the curable Secondary Coating composition disclosed herein for a cross-sectional area of ​​15,000 μm is greater than 36 g, or greater than 40 g, or greater than 44 g, or greater than 48 g, or in the range of 36 g to 52 g, or in the range of 40 g to 48 g. 2 The puncture load of a Secondary Coating formed as the cured product of the curable Secondary Coating composition disclosed herein for a cross-sectional area of ​​20,000 μm is greater than 56 g, or greater than 60 g, or greater than 64 g, or greater than 68 g, or in the range of 56 g to 72 g, or in the range of 60 g to 68 g. 2 The puncture load of a Secondary Coating formed as the cured product of the curable Secondary Coating composition disclosed herein for a cross-sectional area of ​​greater than 68 g, or greater than 72 g, or greater than 76 g, or greater than 80 g, or in the range of 68 g to 92 g, or in the range of 72 g to 88 g. Embodiments include Secondary Coatings having any combination of the foregoing puncture loads.

[0319] As used herein, normalized puncture load refers to the ratio of puncture load to cross-sectional area. The puncture load of a Secondary Coating formed as the cured product of the curable Secondary Coating composition disclosed herein is 3.0 x 10 -3 g / μm 2 Super, or 3.5 x 10 -3 g / μm2 Super, or 4.0 x 10 -3 g / μm 2 Super, or 4.5 x 10 -3 g / μm 2 Over, or 5.0 x 10 -3 g / μm 2 Super, or 3.2 x 10 -3 g / μm 2 to 5.6 x 10 -3 g / μm 2 range, or 3.5 x 10 -3 g / μm 2 to 5.2 x 10 -3 g / μm 2 range, or 4.0 x 10 -3 g / μm 2 to 4.8 x 10 -3 g / μm 2 The normalized puncture load ranges from 0.01 to 0.1.

[0320] Example - Relative Refractive Index Profile The following examples illustrate representative relative refractive index profiles and optical properties for optical fibers with low macrobend losses. The relative refractive index profiles are shown in Figures 8A and 8B. Profile 1, Profile 2, and Profile 3 are shown. Each profile includes, in order of increasing radial position starting from the centerline (r = 0), a core region, an inner cladding region, an intermediate cladding region, and an outer cladding region. The outer cladding region extends to a radius r = 40.0 μm (not shown). The core region of each of the three profiles is alkali-doped silica glass. The inner cladding region, intermediate cladding region, and outer cladding region of each of the three profiles are fluorine-doped silica glass. The fluorine doping concentration is highest in the intermediate cladding region and lower in the inner and outer cladding regions.

[0321] Macrobend. The macrobend loss at 1550 nm of the optical fiber for each of the three profiles was calculated for mandrels of various diameters. The macrobend loss is calculated using the "BL DM", where "DM" is the diameter in mm of the mandrel used to evaluate macrobend performance. Diameter DM is also referred to herein as the "macrobend diameter." Macrobend performance, as described herein, is determined by characterizing the attenuation increase induced in a mandrel-wound test, unless otherwise specified. The mandrel-wound test is specified in TIA-455-62:FOTP-62 IEC-60793-1-47 Optical Fibers - Part 1-47: Measurement Methods and Test Procedures - Macrobending Loss, by the Telecommunications Industry Association (TIA). In this mandrel-wound test, optical fiber is wrapped one or more times around a smooth, cylindrical mandrel of diameter DM, and the increase in attenuation at a specified wavelength due to bending is determined. Attenuation in the mandrel-wound test is expressed in units of dB / turn, where one turn refers to one revolution of the optical fiber around the mandrel. Bending loss values ​​for mandrel diameters of 15 mm, 20 mm and 30 mm, i.e., BL 15 , B.L. 20 , and B.L. 30 is given below.

[0322] The bending loss and selected optical properties of each of the three profiles are summarized in Table 10. In Table 10, "MFD" refers to the mode field diameter, λ refers to the zero dispersion wavelength, and λ CC is the cable cutoff wavelength, and V トレンチ refers to the trench volume.

[0323] [Table 10]

[0324] The macrobend loss of the optical fiber at a wavelength of 1550 nm when wound on a 30 mm diameter mandrel is less than 0.010 dB / turn, or less than 0.005 dB / turn, or less than 0.002 dB / turn, or less than 0.001 dB / turn, or less than 0.00005 dB / turn. The macrobend loss of the optical fiber at a wavelength of 1550 nm when wound on a 20 mm diameter mandrel is less than 0.100 dB / turn, or less than 0.050 dB / turn, or less than 0.010 dB / turn, or less than 0.005 dB / turn, or less than 0.001 dB / turn, or less than 0.0005 dB / turn. The macrobend loss of the optical fiber at a wavelength of 1550 nm when wound on a 15 mm diameter mandrel is less than 0.500 dB / turn, or less than 0.100 dB / turn, or less than 0.050 dB / turn, or less than 0.040 dB / turn, or less than 0.030 dB / turn, or less than 0.020 dB / turn, or less than 0.015 dB / turn.

[0325] The wire mesh coated drum microbend loss at 1550 nm is less than 1.0 dB / km, or less than 0.75 dB / km, or less than 0.50 dB / km, or less than 0.25 dB / km, or less than 0.10 dB / km, or less than 0.05 dB / km, or less than 0.03 dB / km, or in the range of 0.01 dB / km to 1.0 dB / km, or in the range of 0.02 dB / km to 0.50 dB / km, or in the range of 0.03 dB / km to 0.25 dB / km, or in the range of 0.04 dB / km to 0.15 dB / km.

[0326] Example - Optical fiber with reduced radius The following examples demonstrate reduced-radius optical fibers with high mechanical reliability and low microbending losses. A conventional optical fiber comprises a glass fiber with a radius r4 = 62.5 μm, a primary coating with a thickness r5 - r4 = 32.5 μm, and a secondary coating with a thickness r6 - r5 = 26 μm. The radius r6 of the conventional optical fiber is 121 μm (diameter 2r6 = 242 μm). The exemplary optical fiber disclosed in the following examples has a radius r6 of 100 μm or less. The reduced radius of the exemplary optical fiber is achieved by reducing one or more of the glass fiber radius r4, the thickness r5 - r4 of the primary coating, or the thickness r6 - r5 of the secondary coating relative to the conventional optical fiber.

[0327] Table 11 summarizes selected properties of a series of comparative optical fibers (designated CE1, CE2, CE3, CE4, and CE5), and Table 12 summarizes selected properties of a series of exemplary optical fibers (designated Ex. 1, Ex. 2, Ex. 3, Ex. 4, Ex. 5, and Ex. 6) according to the present disclosure. Tables 11 and 12 include the radius r4 of the glass fiber, the in-situ elastic modulus (E p ), radius of primary coating r5, thickness of primary coating r5-r4, spring constant χp of primary coating, Young's modulus of secondary coating (E s ), radius of secondary coating r6, thickness of secondary coating r6-r5, cross-sectional area of ​​secondary coating (A x ), and the ratio of the primary coating thickness r5-r4 to the secondary coating thickness r6-r5 (R ps ) are listed.

[0328] [Table 11]

[0329] The comparative optical fibers CE1, CE2, and CE3 have glass fiber radius r4, primary coating thickness r5-r4, and secondary coating thickness r6-r5 that are consistent with conventional optical fibers. The radius r6 of the comparative optical fibers CE1, CE2, and CE3 defines the current standard for fiber density in cables. To increase fiber density in cables, optical fibers with lower values ​​of r6 are desirable. However, optical fibers with such reduced radius must provide high mechanical reliability while maintaining low macrobend and microbend losses.

[0330] The comparative optical fiber CE4 is a reduced radius variant of the comparative optical fiber CE1. The mechanical properties (E p and E s ) is the same as that of the comparative optical fiber CE1. The comparative optical fiber CE4 is an optical fiber with a reduced radius obtained by reducing the thickness of the primary coating r5-r4 and the thickness of the secondary coating r6-r5 relative to the comparative optical fiber CE1. Although the overall radius of the optical fiber is reduced, the spring constant χ of the primary coating of the comparative optical fiber CE4 p is too high (too stiff) to adequately protect the glass fiber from external forces applied to the outside of the optical fiber. p This results in strong bonding of the secondary coating to the glass fiber and weak attenuation of the force by the primary coating, and therefore high microbending losses.

[0331] The comparative optical fiber CE5 is a reduced radius variant of the comparative optical fiber CE3. The mechanical properties (E p and E s ) is the same as the comparative optical fiber CE3. The comparative optical fiber CE5 is an optical fiber with a reduced radius obtained by reducing the radius r4 of the glass fiber and the thickness r6-r5 of the secondary coating relative to the comparative optical fiber CE3. The thickness r5-r4 of the primary coating is determined by the spring constant χ of the primary coating. pThe primary coating spring constant χ is increased in the comparative optical fiber CE5 relative to the comparative optical fiber CE3 in order to reduce the overall radius of the optical fiber. p However, the Young's modulus of the comparative optical fiber CE5 is too low to provide high puncture resistance and too low to adequately attenuate the transmission of external forces to the primary coating, resulting in poor mechanical reliability and high microbending loss.

[0332] [Table 12]

[0333] The exemplary optical fiber is fabricated to have a reduced radius r6 relative to conventional optical fibers while achieving both low microbending loss and high mechanical reliability. Specifically, the spring constant χ of the primary coating p is reduced relative to the comparative optical fiber, resulting in low microbending losses. The increased Young's modulus E of the secondary coating s resists the transmission of force through the secondary coating and reduces the force entering the primary coating. The Young's modulus of the secondary coating and the spring constant χ of the primary coating are p The synergistic relationship between provides both low microbending loss and high puncture resistance in optical fibers with reduced radii.

[0334] In a preferred embodiment, the spring constant χ of the primary coating p is less than 1.0 MPa, or less than 0.80 MPa, or less than 0.70 MPa, or less than 0.60 MPa, or less than 0.50 MPa, or less than 0.40 MPa, or in the range of 0.30 MPa to 0.90 MPa, or in the range of 0.30 MPa to 0.80 MPa, or in the range of 0.30 MPa to 0.70 MPa, or in the range of 0.30 MPa to 0.60 MPa, or in the range of 0.40 MPa to 0.90 MPa, or in the range of 0.40 MPa to 0.80 MPa, or in the range of 0.40 MPa to 0.70 MPa, or in the range of 0.40 MPa to 0.60 MPa.

[0335] In another preferred embodiment, the spring constant χ of the primary coating p is less than 1.0 MPa, and the Young's modulus E s The spring constant χ of the primary coating is greater than 1600 MPa. p is less than 0.80 MPa, and the Young's modulus Es of the secondary coating is greater than 1700 MPa, p is less than 0.70 MPa, and the Young's modulus E s The spring constant χ of the primary coating is greater than 1800 MPa. p is less than 0.60 MPa, and the Young's modulus E s The spring constant χ of the primary coating is greater than 1900 MPa. p is less than 0.50 MPa, and the Young's modulus E s The spring constant χ of the primary coating is greater than 2000 MPa. p is in the range of 0.30 MPa to 1.0 MPa, and the Young's modulus E s is the spring constant χ of the primary coating, which is in the range of 1600 MPa to 2800 MPa. p is in the range of 0.30 MPa to 0.80 MPa, and the Young's modulus E s is the spring constant χ of the primary coating, which is in the range of 1700 MPa to 2800 MPa. p is in the range of 0.30MPa to 0.70MPa, and the Young's modulus E s is the spring constant χ of the primary coating, which is in the range of 1800 MPa to 2800 MPa. p is in the range of 0.30MPa to 0.60MPa, and the Young's modulus E s is the spring constant χ of the primary coating, which is in the range of 1900 MPa to 2800 MPa. p is in the range of 0.40 MPa to 1.0 MPa, and the Young's modulus E s is the spring constant χ of the primary coating, which is in the range of 1600 MPa to 2800 MPa. p is in the range of 0.40 MPa to 0.80 MPa, and the Young's modulus E s is the spring constant χ of the primary coating, which is in the range of 1700 MPa to 2800 MPa. pis in the range of 0.40 MPa to 0.70 MPa, and the Young's modulus E s is in the range of 1800 MPa to 2800 MPa, or the spring constant χ of the primary coating p is in the range of 0.40 MPa to 0.60 MPa, and the Young's modulus E s is in the range of 1900 MPa to 2800 MPa.

[0336] The ratio of the primary coating thickness r5-r4 to the secondary coating thickness r6-r5 is in the range of 0.80 to 2.20, or in the range of 0.85 to 1.85, or in the range of 0.90 to 1.50, or in the range of 0.95 to 1.30.

[0337] Example - Optical fiber with reduced radius Further illustrative examples of reduced-radius optical fibers are summarized in Figure 9 and Tables 13 and 14. Each of the reduced-radius optical fibers has a relative refractive index profile that includes an intermediate cladding region surrounding and immediately adjacent to a core region, and an outer cladding region surrounding and immediately adjacent to the intermediate cladding region. Table 13 summarizes selected properties of a series of comparative optical fibers (labeled C1, C2, and C3) and two exemplary optical fibers according to the present disclosure (labeled Ex. 7 and Ex. 8). Table 13 includes the radius r1 and average relative refractive index Δ1 of the core region, the radius r3 and relative refractive index Δ3 of the intermediate cladding region, and the trench volume V トレンチ (=V3), radius of primary coating r5, thickness of primary coating r5-r4, radius of secondary coating r6, thickness of secondary coating r6-r5, cross-sectional area of ​​secondary coating (A x ), and the ratio of the primary coating thickness r5-r4 to the secondary coating thickness r6-r5 (R ps For the optical fibers listed in Tables 13 and 14, the same primary coatings having the same composition and modulus, and the same secondary coatings having the same composition and modulus were used.

[0338] [Table 13]

[0339] Table 14 shows selected performance attributes of the comparative optical fibers C1, C2, and C3, and the exemplary optical fibers Ex. 7 and Ex. 8. The attributes listed in Table 14 are: cable cutoff wavelength λ CC , mode field diameter (MFD) at 1550 nm, effective area A at 1550 nm eff , and the attenuation at 1550 nm and 1625 nm.

[0340] [Table 14]

[0341] The results shown in Table 14 show a clear improvement (reduction) in attenuation at both 1550 nm and 1625 nm for the two exemplary fibers. The reduction in attenuation reflects reduced microbending losses. The reduced attenuation is primarily due to the appropriate selection of primary coating thickness and trench volume. The primary coating thicknesses of Comparative Examples C1, C2, and C3 are too small to provide adequate resistance to microbending forces. Comparative Example C1 does not have a trench. Instead, the average relative refractive index Δ3 of the intermediate cladding region is greater than the average relative refractive index Δ4 of the outer cladding region. This results in the reported negative value of the V-trench listed for Comparative Example C1, and this comparative example effectively has an inverted trench and relative refractive index profile that is predicted to exhibit high microbending losses. Comparative Examples C2 and C3 have the same primary coating thickness and differ primarily in trench volume. The trench volume of Comparative Example C2 is larger than that of Comparative Example C3, and higher attenuation is observed. Although example sample Ex.7 and comparative example C3 have similar trench volumes, the thicker primary coating of example sample Ex.7 results in lower microbending loss and lower attenuation. Example sample Ex.8 has the same thickness of primary coating as example sample Ex.7 and exhibits lower microbending loss and lower attenuation. Without intending to be bound by theory, it is believed that the improved performance of example sample Ex.8 is due to the smaller trench volume. Note that for a given thickness of secondary coating, as the thickness of the primary coating increases, the cross-sectional area of ​​the secondary coating also increases. Increasing the cross-sectional area of ​​the secondary coating improves the puncture resistance of the secondary coating and, therefore, improves the mechanical reliability of the optical fiber.

[0342] These examples demonstrate the dependence of microbending loss and attenuation in reduced radius optical fibers on the thickness of the primary coating and the trench volume of the intermediate cladding region. In various embodiments, the thickness of the primary coating ranges from 25.0 μm to 40.0 μm, and the trench volume of the intermediate cladding region, Vtrench, is 10% Δμm. 2 to 30%Δμm 2 is in the range.

[0343] Example - Attenuation Modeling Results. Figure 10 shows the results of the model used to determine the attenuation as a function of wavelength in two optical fibers. Attenuation is expressed in units of dB / km and represents the loss in intensity of the transmission of an optical signal through the optical fiber. Microbending losses are a significant contributor to attenuation. The attenuation results, shown as lines 120 and 125, are for a common glass fiber with radius r = 40.25 μm, and the same composition and in-situ modulus E p = 0.2 MPa and Young's modulus E s = 1948 MPa. Lines 120 and 125 are based on primary and secondary coatings with different thicknesses. For line 120, the primary coating has a radius r5 = 62.5 μm and a thickness r5 - r4 = 22.25 μm, while the secondary coating has a radius r6 = 80.0 μm and a thickness r6 - r5 = 17.5 μm. For line 125, the primary coating has a radius r5 = 80.0 μm and a thickness r5 - r4 = 39.75 μm, while the secondary coating has a radius r6 = 100.0 μm and a thickness r6 - r5 = 20.0 μm. The results show that the microbending contribution to attenuation loss decreases significantly as the primary coating thickness increases. Model results indicate that a thickness r5 - r4 of at least 20.0 μm is required to achieve acceptable microbending losses at wavelengths near 1550 nm.

[0344] Example - Load on Glass Fiber Modeling Results. The experimental examples and principles disclosed herein demonstrate that by varying the moles n, m, and p, it is possible to control the properties of cured films formed from Primary Coating compositions over a wide range, including the ranges specified herein for the relative amounts of the diaddition compound in the oligomer, as well as the Young's modulus and in situ modulus of the Primary Coating. Similarly, varying the type and concentration of different monomers in the Secondary Coating composition will vary the Young's modulus over the ranges disclosed herein. Cure dose is another parameter that can be used to vary the modulus of Primary and Secondary Coatings formed from the curable compositions disclosed herein.

[0345] A series of modeling examples were considered to investigate the effect of the thickness and modulus of the primary and secondary coatings on the transmission of radial forces to the glass fiber. In the model, a radial external load P was applied to the surface of the secondary coating of an optical fiber, and the resulting load on the surface of the glass fiber was calculated. A glass fiber with a Young's modulus of 73.1 GPa (consistent with silica glass) and a diameter of 125 μm was modeled. The Poisson's ratio ν of the primary and secondary coatings p and ν s were fixed at 0.48 and 0.33, respectively. Comparative sample C4 and eleven samples M1-M11 according to the present disclosure were studied. The comparative samples had primary and secondary coatings with thicknesses and moduli consistent with optical fibers known in the art. Samples M1-M11 are examples where the thickness of the primary and / or secondary coatings was reduced. Parameters describing the configuration of the primary and secondary coatings are summarized in Table 15, where E p is the in-situ elastic modulus of the primary coating, r5 is the radius of the primary coating, r5-r4 is the thickness of the primary coating, and E s is the Young's modulus of the secondary coating, r6 is the radius of the secondary coating, and r6-r5 is the thickness of the secondary coating.

[0346] [Table 15]

[0347] Table 16 summarizes the load P1 at the outer surface of the glass fiber as a function of the load P applied to the surface of the secondary coating. The ratio P1 / P, referred to herein as the load transfer parameter, corresponds to the fraction of the external load P that is transferred through the primary and secondary coatings to the surface of the glass fiber. The load P is the radial load, and the load transfer parameter P1 / P was calculated from a model based on equations (11)-(13):

[0348]

number

[0349] During the ceremony,

[0350]

number

[0351] and

[0352]

number

[0353] In equations (11) to (13), νp and νs are the Poisson's ratios of the primary coating and the secondary coating, r4 is the radius of the glass fiber, r5 is the radius of the primary coating, r6 is the radius of the secondary coating, and E p is the in-situ elastic modulus of the primary coating, and E s is the Young's modulus of the secondary coating. The scaled load transfer parameters P1 / P (scaled) in Table 16 correspond to the ratio P1 / P of each sample relative to the comparative sample C4.

[0354] [Table 16]

[0355] Modeling examples show that, despite the smaller coating thickness, optical fibers having primary and secondary coatings as described herein exhibit reduced forces experienced by the glass fiber relative to comparative optical fibers having conventional primary and secondary coatings with conventional thicknesses. The resulting reduction in overall size of the optical fibers described herein allows for an increase in the total number of fibers in a cable of a given size (or a decrease in cable diameter for a given total number of fibers) without increasing the risk of damage to the glass fiber caused by external forces.

[0356] The scaled load transfer parameter P1 / P (scaled) of the secondary coating is less than 0.99, or less than 0.97, or less than 0.95. The load transfer parameter P1 / P of the secondary coating is less than 0.00440, or less than 0.00436, or less than 0.00432, or less than 0.00428, or less than 0.00424, or less than 0.00420, or less than 0.00416, or less than 0.00412, or in the range of 0.00400 to 0.00440, or in the range of 0.00408 to 0.00436, or in the range of 0.00412 to 0.00432, or in the range of 0.00416 to 0.00428, or in the range of 0.00420 to 0.00424.

[0357] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a particular order. Thus, unless a method claim actually recites the order in which its steps should be followed, or unless the claim or description specifically states otherwise that the steps are limited to a particular order, no particular order is intended to be implied.

[0358] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the present invention. Since modifications, combinations, sub-combinations and variations of the disclosed embodiments that embody the spirit and scope of the invention will occur to those skilled in the art, the present invention is to be construed as including all within the scope of the appended claims and equivalents thereof.

[0359] Preferred embodiments of the present invention will be described below in detail.

[0360] Embodiment 1 In optical fibers, a core region made of silica glass doped with an alkali metal oxide, having a radius r1 ranging from 3.0 μm to 10.0 μm and a maximum relative refractive index Δ ranging from −0.15% to 0.30%; 1max a core region having a relative refractive index profile Δ1 having a cladding region surrounding and immediately adjacent to the core region, the cladding region having a radius r4 in the range of 37.5 μm to 52.5 μm; a primary coating surrounding and immediately adjacent the cladding region, the primary coating having a radius r5 and a spring constant χ p , a primary coating having an in-situ elastic modulus in the range of 0.05 MPa to 0.30 MPa and a thickness r5-r4 in the range of 20.0 μm to 40.0 μm; and a secondary coating surrounding and immediately adjacent to the primary coating, the secondary coating having a radius r6 of 100.0 μm or less, a Young's modulus greater than 1600 MPa, and a thickness r6-r5 in the range of 15.0 μm to 30.0 μm; Optical fiber with.

[0361] Embodiment 2 2. The optical fiber of claim 1, wherein the silica glass is GeO2-free.

[0362] Embodiment 3 3. The optical fiber according to claim 1 or 2, wherein the radius r1 is in the range of 4.0 μm to 8.0 μm.

[0363] Embodiment 4 Δ 1max 4. The optical fiber according to any one of embodiments 1 to 3, wherein σ is in the range of −0.05% to 0.15%.

[0364] Embodiment 5 the core region has a minimum relative refractive index Δ in the range of −0.20% to 0.10% 1min 5. The optical fiber according to any one of embodiments 1 to 4, having:

[0365] Embodiment 6 The core region has a radius r in the range of 0.25 μm to 3.0 μm. a and an outer core region having the radius r1.

[0366] Embodiment 7 7. The optical fiber of embodiment 6, wherein the inner core region has a relative refractive index profile described by an α-profile having an α value of less than 10, and the outer core region has a relative refractive index profile described by an α-profile having an α value of greater than 50.

[0367] Embodiment 8 8. The optical fiber of any one of claims 1 to 7, wherein the cladding region comprises an intermediate cladding region and an outer cladding region surrounding and immediately adjacent to the intermediate cladding region, the intermediate cladding region having a radius r3 and a relative refractive index Δ3 in the range of -0.30% to -0.90%, and the outer cladding region having a radius r4 and a relative refractive index Δ4 in the range of -0.60% to 0.0%.

[0368] Embodiment 9 9. The optical fiber of embodiment 8, wherein the radius r3 is in the range of 10.0 μm to 30.0 μm.

[0369] Embodiment 10 10. The optical fiber of embodiment 8 or 9, wherein the intermediate cladding region has a thickness in the range of 5.0 μm to 20.0 μm.

[0370] Embodiment 11 11. The optical fiber according to any one of embodiments 8 to 10, wherein the relative refractive index Δ3 is in the range of −0.30% to −0.60%.

[0371] Embodiment 12 12. The optical fiber according to any one of embodiments 8 to 11, wherein the intermediate cladding region is immediately adjacent to the core region.

[0372] Embodiment 13 The intermediate cladding region has a thickness of 10.0% Δμm 2 to 40.0%Δμm 2 Trench volume V in the range トレンチ 13. The optical fiber of embodiment 12, having

[0373] Embodiment 14 the intermediate cladding region has a thickness of 15.0% Δμm 2 to 30.0%Δμm 2 Trench volume V in the range トレンチ 13. The optical fiber of embodiment 12, having

[0374] Embodiment 15 The cladding region further includes an inner cladding region that surrounds and is immediately adjacent to the core region, the inner cladding region having a radius r ranging from 6.0 μm to 18.0 μm and the relative refractive index Δ 1max 12. The optical fiber of any one of embodiments 8 to 11, wherein the intermediate cladding region has a relative refractive index Δ2 smaller than the inner cladding region Δ1 and greater than the relative refractive index Δ3, and the intermediate cladding region surrounds and is directly adjacent to the inner cladding region.

[0375] Embodiment 16 16. The optical fiber according to embodiment 15, wherein the relative refractive index Δ2 is in the range of −0.45% to −0.15%.

[0376] Embodiment 17 17. The optical fiber according to embodiment 15 or 16, wherein the inner cladding region has a thickness r2-r1 in the range of 3.0 μm to 9.0 μm.

[0377] Embodiment 18 The intermediate cladding region has a thickness of 20% Δμm 2 to 70%Δμm 2 Trench volume V in the range トレンチ 18. The optical fiber according to any one of embodiments 15 to 17, having

[0378] Embodiment 19 The intermediate cladding region has a thickness of 40% Δμm 2 Trench volume V トレンチ 19. The optical fiber according to any one of embodiments 15 to 18, having

[0379] Embodiment 20 20. The optical fiber according to any one of embodiments 8 to 19, wherein the relative refractive index Δ4 is ​​in the range of −0.45% to −0.15%.

[0380] Embodiment 21 21. The optical fiber according to any one of embodiments 1 to 20, wherein the radius r4 is in the range of 37.5 μm to 47.5 μm.

[0381] Embodiment 22 22. The optical fiber according to any one of embodiments 1 to 21, wherein the radius r5 is 85.0 μm or less.

[0382] Embodiment 23 23. The optical fiber according to any one of embodiments 1 to 22, wherein the thickness r5-r4 is in the range of 25.0 μm to 37.5 μm.

[0383] Embodiment 24 The spring constant χ p 24. The optical fiber of any one of embodiments 1 to 23, wherein the tensile strength is less than 0.50 MPa.

[0384] Embodiment 25 25. The optical fiber of any one of embodiments 1 to 24, wherein the Young's modulus is greater than 2000 MPa.

[0385] Embodiment 26 The primary coating is radiation-curable monomers, an adhesion promoter comprising an alkoxysilane compound or a mercapto-functional silane compound, and an oligomer, Molecular formula:

[0386] [ka]

[0387] wherein R1, R2, and R3 are independently selected from a linear alkylene group, a branched alkylene group, or a cyclic alkylene group; y is 1, 2, 3, or 4; x is between 40 and 100, a polyether urethane acrylate compound having the formula: Molecular formula:

[0388] [ka]

[0389] a diaddition compound present in the oligomer in an amount of at least 1.0 wt. % having the formula: an oligomer comprising 26. The optical fiber of any one of the previous embodiments, wherein the optical fiber is a cured product of a coating composition comprising:

[0390] Embodiment 27 27. The optical fiber of embodiment 26, wherein the diaddition compound is present in the oligomer in an amount of at least 3.5 wt.%.

[0391] Embodiment 28 The oligomer is diisocyanate compounds, hydroxy(meth)acrylate compounds, and a polyol compound having an unsaturation level of less than 0.1 meq / g; and wherein the cured product is a reaction product between 28. The optical fiber of embodiment 26 or 27, wherein the diisocyanate compound, the hydroxy(meth)acrylate compound, and the polyol compound are reacted in a molar ratio of n:m:p, respectively, where n is in the range of 3.0 to 5.0, m is within ±15% of 2n-4, and p is 2.

[0392] Embodiment 29 29. The optical fiber according to any one of embodiments 1 to 28, wherein the radius r6 is 90.0 μm or less.

[0393] Embodiment 30 30. The optical fiber of any one of embodiments 1 to 29, wherein the Young's modulus is greater than 2000 MPa.

[0394] Embodiment 31 31. The optical fiber according to any one of embodiments 1 to 30, wherein the thickness r6-r5 is in the range of 15.0 μm to 25.0 μm.

[0395] Embodiment 32 The secondary coating is an amount greater than 55% by weight of an alkoxylated bisphenol-A diacrylate monomer, the alkoxylated bisphenol-A diacrylate monomer having a degree of alkoxylation ranging from 2 to 16; and a triacrylate monomer in an amount ranging from 2.0% to 25% by weight, the triacrylate monomer comprising an alkoxylated trimethylolpropane triacrylate monomer or a tris[(acryloyloxy)alkyl]isocyanurate monomer having an alkoxylation degree ranging from 2 to 16; 32. The optical fiber of any one of the previous embodiments, wherein the optical fiber is the cured product of a composition comprising:

[0396] Embodiment 33 33. The optical fiber of embodiment 32, wherein the triacrylate monomer is present in an amount ranging from 8.0% to 15% by weight.

[0397] Embodiment 34 34. The optical fiber of embodiment 32 or 33, wherein the alkoxylated trimethylolpropane triacrylate monomer has a degree of alkoxylation ranging from 2 to 8.

[0398] Embodiment 35 35. The optical fiber of any one of embodiments 32 to 34, wherein the alkoxylated trimethylolpropane triacrylate monomer is an ethoxylated trimethylolpropane triacrylate monomer.

[0399] Embodiment 36 36. The optical fiber of any one of embodiments 32 to 35, wherein the tris[(acryloyloxy)alkyl]isocyanurate monomer is tris(2-hydroxyethyl)isocyanurate triacrylate monomer.

[0400] Embodiment 37 The optical fiber has an effective area of ​​70 μm at 1550 nm. 2 37. The optical fiber of any one of embodiments 1 to 36, wherein the optical fiber is greater than

[0401] Embodiment 38 The optical fiber has an effective area of ​​100 μm at 1550 nm. 2 37. The optical fiber of any one of embodiments 1 to 36, wherein the optical fiber is greater than

[0402] Embodiment 39 39. The optical fiber of any one of the preceding embodiments, wherein the optical fiber has a macrobending loss at a wavelength of 1550 nm of less than 0.5 dB / turn when wound around a 15 mm diameter mandrel.

[0403] Embodiment 40 40. The optical fiber of any one of the preceding embodiments, wherein the optical fiber has a wire mesh coated drum microbending loss at a wavelength of 1550 nm of less than 0.5 dB / km.

[0404] Embodiment 41 41. The optical fiber of any one of embodiments 1 to 40, wherein the optical fiber has a wire mesh coated drum microbending loss at a wavelength of 1550 nm of less than 0.03 dB / km.

[0405] Embodiment 42 The secondary coating is 3.5×10 -3 g / μm 2 42. The optical fiber of any one of embodiments 1-41, having a normalized puncture load of greater than

[0406] Embodiment 43 The secondary coating is 4.5×10-3 g / μm 2 42. The optical fiber of any one of embodiments 1-41, having a normalized puncture load of greater than

[0407] EMBODIMENT 44 The ratio R of the thickness r5-r4 of the primary coating to the thickness r6-r5 of the secondary coating ps 44. The optical fiber of any one of embodiments 1 to 43, wherein β is in the range of 0.90 to 1.50.

[0408] Embodiment 45 45. The optical fiber of any one of embodiments 1 to 44, further comprising a tertiary coating surrounding and immediately adjacent to the secondary coating, the tertiary coating having a thickness in the range of 2.0 μm to 8.0 μm. [Explanation of symbols]

[0409] 10, 20, 46 optical fiber 11,60 Glass fiber 12 Core Areas 14 Cladding region 16, 56 Primary coating 18, 58 Secondary coating 30 Optical Fiber Ribbon 32 Matrix 40 Fiber Optic Cable 42 Jacket 48 Core Areas 50 Cladding area 51 inner cladding region 53 Intermediate cladding region 55 outer cladding region

Claims

1. In optical fibers, a core region made of alkali metal oxide-doped and Ge-free silica glass, the core region having a radius r in the range of 3.0 μm to 10.0 μm; １ and a maximum relative refractive index Δ ranging from −0.026% to 0.12% １ｍａｘ a relative refractive index profile Δ １ a core region having a cladding region surrounding and immediately adjacent the core region, the cladding region having a radius r in the range of 40.25 μm to 52.5 μm; ４ a cladding region having a primary coating surrounding and immediately adjacent the cladding region, the primary coating having a radius r ５ , spring constant χ ｐ , in-situ elastic modulus ranging from 0.18 MPa to 0.25 MPa, and thickness r ranging from 21.0 μm to 39.75 μm. ５ -r ４ a primary coating having a secondary coating surrounding and immediately adjacent to the primary coating, the secondary coating having a radius r in the range of 80.0 μm to 100.0 μm; ６ , Young's modulus in the range of 1882 MPa to 2000 MPa, and thickness r in the range of 16.5 μm to 29.0 μm. ６ -r ５ a secondary coating having Optical fiber with.

2. The cladding region includes an intermediate cladding region and an outer cladding region surrounding and immediately adjacent to the intermediate cladding region, the intermediate cladding region having a radius r in the range of 10.0 μm to 30.0 μm. ３ , and a relative refractive index Δ ranging from −0.30% to −0.90% ３ and the outer cladding region has a radius r ４ , and a relative refractive index Δ ranging from −0.60% to 0.0% ４ The optical fiber of claim 1 , wherein

3. The optical fiber of claim 2 , wherein the intermediate cladding region has a thickness in the range of 5.0 μm to 20.0 μm.

4. The optical fiber of claim 2 or 3, wherein said intermediate cladding region is immediately adjacent to said core region.

5. The intermediate cladding region has a thickness of 10.0% Δμm ２ to 40.0% Δμm ２ Trench volume V in the range トレンチ The optical fiber according to any one of claims 2 to 4, wherein

6. The cladding region further includes an inner cladding region that surrounds and is immediately adjacent to the core region, the inner cladding region having a radius r in the range of 6.0 μm to 18.0 μm. ２ and the relative refractive index Δ １ｍａｘ is smaller than the relative refractive index Δ ３ Larger relative refractive index Δ ２ 3. The optical fiber of claim 2, wherein said intermediate cladding region surrounds and is immediately adjacent to said inner cladding region.

7. The relative refractive index Δ ２ The optical fiber of claim 6, wherein is in the range of -0.55% to -0.05%.

8. The relative refractive index Δ ２ is in the range of −0.45% to −0.15%, and the inner cladding region has a thickness r ２ -r １ The optical fiber of claim 7 , wherein

9. The intermediate cladding region has a thickness of 20% Δμm ２ to 70% Δμm ２ Trench volume V in the range トレンチ The optical fiber according to any one of claims 6 to 8, having

10. The relative refractive index Δ ４ The optical fiber according to any one of claims 2 to 9, wherein is in the range of -0.55% to -0.05%.

11. The relative refractive index Δ ４ The optical fiber according to any one of claims 2 to 10, wherein is in the range of -0.45% to -0.15%.

12. The radius r ５ The optical fiber according to claim 1 , wherein the λ / 2 is equal to or less than 85.0 μm.

13. The radius r ６ The optical fiber according to claim 1 , wherein the λ / 2 is 90.0 μm or less.

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