Full-dry type optical unit, optical cable and manufacturing method thereof

Abstract

The invention discloses a full-dry optical cable and a manufacturing method thereof, and belongs to the technical field of optical communication, the full-dry optical cable comprises at least one optical fiber, the periphery of the optical fiber is sleeved with a sleeve, a gap is reserved between the optical fiber and the sleeve, and the gap is filled with a water blocking sheet. Specifically, the water blocking sheet is in a sheet shape, the ratio of the size of the water blocking sheet in the length direction to the size of the water blocking sheet in the width direction or the thickness direction is (5-20): 1, and the specific surface area of the water blocking sheet is 0.09-0.8 / mu m. According to the optical unit, the water blocking sheet is arranged to be of the sheet-shaped structure, and when the water blocking sheet is arranged in the sleeve, the water blocking sheet can be flatly arranged in the axial direction or the circumferential direction of the sleeve, so that compared with conventional water blocking powder, the water blocking sheet does not obviously increase the overall radial size of the optical unit in the thickness direction; under the condition of not increasing the overall size of the full-dry type optical unit and the use amount of an internal water-blocking material, rapid water blocking of the full-dry type optical unit is realized.

Description

Technical Field

[0001] This invention belongs to the field of optical communication technology, specifically relating to an all-dry optical cable and its manufacturing method. Background Technology

[0002] With the comprehensive advancement of 5G network construction and green manufacturing, the large-scale construction of optical networks has placed higher demands on low-carbon environmental protection and resource conservation. Furthermore, with the increasing scarcity of pipeline network resources, the high resource consumption of optical cable manufacturing itself has become a current industry challenge.

[0003] When water enters the interior of an optical cable, the transmission loss of the optical fiber itself increases, affecting signal transmission efficiency. If metal reinforcements are used inside the cable, they are prone to corrosion from prolonged immersion in water, and water adhering to the fiber surface makes it more susceptible to breakage. Therefore, a water-blocking structure is usually required inside the optical cable. Existing optical cable structures are mainly divided into dry water-blocking and wet water-blocking. Wet water-blocking mainly involves filling the outer perimeter of the sleeve with water-blocking paste to achieve water blocking inside the cable. However, the amount of water-blocking paste used is large, and due to the operating environment of the optical cable, fiber optic splicing is required. During fiber splicing, the paste on the fiber surface needs to be removed, which is time-consuming and labor-intensive, affecting the construction efficiency of the optical cable. Moreover, as an organic substance, the paste greatly increases the carbon emissions of the optical cable, which is inconsistent with the current trend of green optical cable development. In contrast, dry water-blocking methods such as water-blocking powder and water-blocking yarn have the advantages of easy cleaning, no paste pollution, and light weight. Dry water-blocking is gradually replacing water-blocking paste and has become the mainstream water-blocking method for optical cables. However, water-blocking yarn is usually quite large, about 500um, which increases the overall size of the optical cable and reduces the fiber density. As particulate matter, water-blocking powder is not constrained inside the cable, which makes it easy for the water-blocking powder to slide relatively inside the optical cable, resulting in uneven distribution of the water-blocking powder and affecting the water-blocking performance of the optical cable. Summary of the Invention

[0004] In response to one or more of the above-mentioned defects or improvement needs of the prior art, the present invention provides an all-dry optical unit, optical cable and manufacturing method to solve the problems of the large overall size of the existing water-blocking yarn affecting the fiber density and the poor water-blocking effect of the water-blocking powder.

[0005] To achieve the above objectives, the present invention provides an all-dry optical unit, comprising: At least one optical fiber, the outer periphery of which is covered by a sleeve, and a gap is left between the optical fiber and the sleeve, the gap being filled with a water-blocking sheet; The water-blocking sheet is sheet-shaped, and the ratio of the length dimension of the water-blocking sheet to the width or thickness dimension of the water-blocking sheet is 5~20:1. The specific surface area of ​​the water-blocking sheet is 0.09~0.8 / um.

[0006] As a further improvement of the present invention, the length direction of the water-blocking sheet is consistent with the axial direction of the sleeve, and the filling rate of the water-blocking sheet in the gap is 12~32mg / m.

[0007] As a further improvement of the present invention, the water-blocking sheet has a water absorption expansion coefficient of not less than 420 ml / g.

[0008] As a further improvement of the present invention, the water-blocking sheet has a length dimension of 60~150μm.

[0009] This application also includes a fully dry optical cable, which includes the fully dry optical unit, and the outer periphery of the sleeve is further provided with an outer sheath.

[0010] As a further improvement of the present invention, a water-blocking sheet is provided between the sleeve and the outer sheath, and part of the water-blocking sheet is attached to the inner wall of the outer sheath, and the average concentration of the water-blocking sheet is not greater than 200 mg / m³.

[0011] This application also includes a method for preparing an all-dry optical cable, comprising the following steps: Obtain the water-blocking substrate and cut it into water-blocking sheets using a shearing machine; The first screening is for water-blocking sheets with a size of 60~150μm, and the second screening is for water-blocking sheets with an aspect ratio or length-to-height ratio of 5~20:1. The optical fiber is introduced into the sleeve, and the water-blocking plate is blown into the sleeve to obtain a fully dry optical unit. An outer sheath is extruded around the periphery of the all-dry optical unit to obtain an all-dry optical cable.

[0012] As a further improvement of the present invention, the secondary screening process of the water-blocking sheet is as follows: the water-blocking sheet is initially screened into spherical, sheet-like and irregular parts using centrifugal separation technology, and sheet-like water-blocking sheets are selected; the sheet-like water-blocking sheets are classified using an air classifier, and water-blocking sheets with different aspect ratios or length-to-height ratios are air-blown and diverted to different regions, and water-blocking sheets with aspect ratios or length-to-height ratios of 5 to 20:1 are selected as the water-blocking material for the all-dry optical cable.

[0013] As a further improvement of the present invention, the water-blocking sheet in this application is blown into the inside of the sleeve through a sleeve extrusion die, wherein the sleeve extrusion die includes: A mold core and a mold cover, wherein an opening for the sleeve material to pass through is formed between the mold core and the mold cover; The core has a first channel pre-reserved, which is located at the center of the core and is used for optical fiber to pass through; A second channel is provided on the outer periphery of the first channel. The second channel is arranged in a ring and is used to transport the water-blocking sheet. A third channel is also provided on the outer periphery of the second channel. The outer periphery wall of the second channel is provided with a plurality of negative pressure adsorption holes. The third channel is connected to the second channel through the negative pressure adsorption holes, and the second channel is under negative pressure.

[0014] As a further improvement of the present invention, the blowing of the water-blocking sheet includes the following steps: The sleeve is produced using a sleeve extrusion die, and the optical fiber is introduced into the first channel. The optical fiber is produced together with the sleeve. The water-blocking sheet is blown into the second channel, filling the gap between the optical fiber and the sleeve; the airflow velocity in the second channel is adjusted so that the transmission rate of the water-blocking sheet in the second channel is similar to the production rate of the sleeve. Apply negative pressure to the third channel and adjust the arrangement of the water-blocking plates in the second channel.

[0015] The aforementioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0016] In summary, the beneficial effects of the above-described technical solutions conceived by this invention compared with the prior art include: (1) The all-dry optical unit of the present invention fills the space between the optical fiber and the sleeve with a water-blocking sheet, which replaces the traditional water-blocking powder. When water seeps into the optical cable, the water-blocking sheet has a larger specific surface area than the conventional water-blocking powder, which can quickly absorb water and expand, thereby achieving rapid water blocking of the optical cable and improving the water blocking efficiency of the optical cable. Secondly, by setting the water-blocking sheet as a sheet structure, when it is arranged in the sleeve, the water-blocking sheet can be arranged flat along the axial direction or circumferential direction of the sleeve, so that the water-blocking sheet does not significantly increase the overall radial dimension of the optical unit in the thickness direction compared with the conventional water-blocking powder. It achieves rapid water blocking of the all-dry optical unit without increasing the overall size of the all-dry optical unit and the amount of internal water-blocking material.

[0017] (2) In the dry optical cable of the present invention, the water blocking sheet itself has a large specific surface area, which makes the surface tension of the water blocking sheet greater than that of the water blocking powder. This makes the adhesion between the optical fiber and the inner wall of the sleeve, and between the sleeve and the outer sheath greater. This ensures that during the cable winding, laying and installation process, the water blocking sheet will prevent the units inside the optical cable from easily slipping, further ensuring the uniformity of the water blocking sheet filling inside the optical cable and ensuring the stability of the water blocking performance of the optical cable. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the all-dry optical cable in an embodiment of the present invention; Figure 2 This is a partial cross-sectional structural diagram of the extrusion die in an embodiment of the present invention; Figure 3This is a schematic diagram of the structure of the second channel in an embodiment of the present invention; Figure 4 This is a diagram showing the water-blocking test results of the sample in an embodiment of the present invention.

[0019] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1. Optical fiber; 2. Sleeve; 3. Water-blocking plate; 4. Reinforcing core; 5. Filler rope; 6. Armor layer; 7. Outer sheath; 8. Extrusion die; 801. Mold core; 802. Mold cover; 803. First channel; 804. Second channel; 805. Third channel; Detailed Implementation To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0020] Furthermore, unless otherwise stated, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0021] Example: Please see Figures 1-4 In a preferred embodiment of the present invention, the all-dry optical unit includes at least one optical fiber 1. A sleeve 2 is fitted around the outer periphery of the optical fiber 1, and a gap is left between the optical fiber 1 and the sleeve 2. The gap is filled with a water-blocking sheet 3. Specifically, the water-blocking sheet 3 is sheet-shaped, and the ratio of the dimension of the water-blocking sheet 3 along the length direction to the dimension of the water-blocking sheet 3 along the width direction or thickness direction is 5~20:1. The specific surface area of ​​the water-blocking sheet 3 is 0.09~0.8 μm.

[0022] Specifically, the all-dry optical unit in this application fills the space between the optical fiber 1 and the sleeve 2 with a water-blocking sheet 3, replacing traditional water-blocking powder. When water seeps into the optical cable, the water-blocking sheet 3 has a larger specific surface area than conventional water-blocking powder, allowing it to quickly absorb water and expand, thus achieving rapid water blocking and improving the water blocking efficiency of the optical cable. Secondly, by setting the water-blocking sheet 3 as a sheet-like structure, when it is arranged inside the sleeve 2, the water-blocking sheet 3 can be arranged flat along the axial direction or circumferential direction of the sleeve 2. This ensures that the water-blocking sheet 3 does not significantly increase the overall radial dimension of the optical unit in the thickness direction compared to conventional water-blocking powder. This achieves rapid water blocking of the all-dry optical unit without increasing the overall size of the unit or the amount of internal water-blocking material used.

[0023] More preferably, the length direction of the water-blocking sheet 3 in this application is consistent with the axial direction of the sleeve 2, the water absorption capacity of the water-blocking sheet 3 is not less than 420 ml / g per minute, and the filling rate of the gap between the optical fiber 1 and the sleeve 2 by the water-blocking sheet 3 is 12~32 mg / m. By controlling the arrangement direction of the water-blocking sheet 3 in the sleeve 2, this application facilitates the rapid blowing of the water-blocking sheet 3 into the sleeve 2, and also ensures that the gap between the optical fiber 1 and the sleeve 2 is evenly blocked when the water-blocking sheet 3 absorbs water and expands, thus avoiding the problem of unevenly arranged water-blocking sheets 3 causing gaps between the optical fiber 1 and the sleeve 2 that affect the water-blocking effect.

[0024] Preferably, it is ideal that the length direction of the water-blocking plate 3 in this application is completely aligned with the axial direction of the sleeve 2. Under normal circumstances, when more than 60% of the length direction of the water-blocking plate 3 extends along the axial direction of the sleeve 2, the filling rate of the gap by the water-blocking plate 3 is between 12 and 32 mg / m, and the water-blocking plate 3 can complete the water blocking between the optical fiber 1 and the sleeve 2.

[0025] Furthermore, as a preferred embodiment of the present invention, the water-blocking sheet 3 has a length dimension of 60~150μm. Normally, the particle size of water-blocking powder is between 80~180μm. The overall size of the water-blocking sheet 3 in this application is comparable to the size of the water-blocking powder, with its length exceeding the diameter of the water-blocking powder, and its width and thickness being similar to the diameter of the water-blocking powder. This facilitates the preparation of the water-blocking sheet 3 and avoids significant modifications to the air-blowing equipment. It also meets the requirements for air-blowing water blocking of various cable types of optical cables, preventing the water-blocking sheet 3 from failing to be blown into the sleeve 2 due to a large difference in size between the water-blocking sheet 3 and the water-blocking powder.

[0026] This application includes a fully dry optical cable, which includes the aforementioned fully dry optical unit, and an outer sheath 7 is provided on the outer periphery of the sleeve 2.

[0027] Optionally, a water-blocking sheet 3 or water-blocking powder is also provided between the sleeve 2 and the outer sheath 7 to achieve water blocking between the optical unit and the sheath. In this application, the area of ​​water adhering to the inner wall of the sleeve 2 or sheath is no more than 35% and no less than 12%. At least 45 wt% of the water-blocking material is adhered to the inner wall of the sleeve 2 / sheath, and at least 5 wt% of the water-blocking material is adhered to the outer wall of the optical fiber 1 or sleeve 2. The average water-blocking material content per unit length of sleeve 2 is no greater than 40 mg / m, and the average water-blocking material content per unit length of sheath is no greater than 200 mg / m. As a result, the concentration of water-blocking material in the produced sleeve is relatively low, and the water-blocking material is firmly adhered to the inner wall of the sleeve and the optical fiber. When the optical fiber is pulled out of the sleeve, no water-blocking material visible to the naked eye diffuses into the air. In addition, the sleeve also has a good water-blocking effect. A 1-meter sample is taken for a water seepage test, and it can remain leak-free for at least 24 hours under a 1-meter water column pressure.

[0028] In the all-dry optical cable of this application, the water-blocking sheet 3 has a large specific surface area, which makes the surface tension of the water-blocking sheet 3 greater than that of the water-blocking powder. This results in greater adhesion between the optical fiber 1 and the inner wall of the sleeve 2, and between the sleeve 2 and the outer sheath 7. As a result, during the cable winding, laying and installation process, the water-blocking sheet 3 prevents the internal units of the optical cable from easily slipping, further ensuring the uniformity of the water-blocking sheet 3 inside the optical cable and ensuring the stability of the water-blocking performance of the optical cable.

[0029] Meanwhile, the outer sheath 7 contains multiple dry optical units, and a reinforcing core 4 is located at the center of the outer sheath 7. The multiple dry optical units are twisted and arranged around the outer periphery of the reinforcing core 4. Furthermore, an armor layer 6 is provided between the outer sheath 7 and the sleeve 2. The armor layer 6 is formed by splicing multiple steel strips or FRP sheets, and a cable opening rope is also provided on the inner side of the outer sheath 7.

[0030] Optionally, depending on user needs, some of the all-dry optical units inside the all-dry optical cable can be replaced by filler rope 5.

[0031] Furthermore, regarding the all-dry optical cable of this application, this application includes a method for manufacturing an all-dry optical cable, which includes the following steps: Obtain the water-blocking substrate and cut it into water-blocking sheets 3 using a shearing machine; The first screening is for water-blocking sheets 3 with a size of 60~150μm, and the second screening is for water-blocking sheets 3 with a length-to-width or length-to-height ratio of 5~20:1; Fiber 1 is introduced into sleeve 2, and water-blocking sheet 3 is blown into sleeve 2 to obtain a fully dry optical unit. An outer sheath 7 is prepared by extrusion around the periphery of the all-dry optical unit to obtain an all-dry optical cable.

[0032] Specifically, the water-blocking matrix in this application can be purchased directly or prepared in-house. The water-blocking matrix is ​​a honeycomb foamed resin of sodium polyacrylate, which has a foamed structure and a large specific surface area. This water-blocking matrix can be obtained by crosslinking polymerization of sodium acrylate.

[0033] Specifically, the screening process in this application includes: firstly, cutting sodium polyacrylate into fragments using a shearing machine; then, drying the cut water-blocking sheet 3 at 75-85°C for 10-20 minutes; and finally, filtering the cut water-blocking sheet 3 through 100-mesh and 250-mesh sieves to obtain a water-blocking sheet 3 with a size between 60 and 150 μm.

[0034] More preferably, the secondary screening in this application specifically includes: classifying the water-blocking sheet 3 using centrifugal separation technology, and then classifying the water-blocking sheet 3 again using an air classifier, and screening out water-blocking sheets 3 with an aspect ratio or length-to-height ratio of 5 to 20:1.

[0035] Specifically, centrifugal separation technology can initially separate spherical, sheet-like, and irregularly shaped water-blocking sheets 3 to obtain sheet-like water-blocking sheet 3 structures. Secondly, a secondary classification is performed using an air classifier. Water-blocking sheets 3 with different aspect ratios or length-to-height ratios have different specific surface areas, and these sheets will be distributed into different ranges under air classifier conditions. Water-blocking sheets 3 with aspect ratios of 5 to 20:1 are then selected. Simultaneously, because the honeycomb-like foamed sodium polyacrylate has good adsorption capacity, moisture in the air will affect the weight of the water-blocking sheet 3, leading to deviations in centrifugal separation and air classifier classification. Therefore, this application includes drying after shearing to ensure the dryness of the water-blocking sheet 3.

[0036] Optionally, after screening, the water-blocking sheet 3 with an aspect ratio or height ratio of 5 to 20:1 can be filtered again through 100-mesh and 250-mesh screens.

[0037] Furthermore, as a preferred embodiment of the present invention, the water-blocking sheet 3 is blown into the gap between the optical fiber 1 and the sleeve 2 when the sleeve 2 is formed outside the optical fiber 1. Specifically, the present application extracts the workshop air source, dries the gas, inputs the dried gas into a refrigerated dryer, then inputs it into a pressure stabilizing tank for pressure stabilization, then leads the water-blocking sheet 3 to the air outlet of the pressure stabilizing tank, and finally blows the water-blocking sheet 3 into the die head and into the sleeve 2 extrusion die 8, where it is filled into the sleeve 2 together with the optical fiber 1.

[0038] Since this application requires ensuring that the length direction of the water-blocking sheet 3 is aligned with the axial direction of the sleeve 2, the arrangement of the water-blocking sheet 3 within the mold is extremely important. As one aspect, this application controls the airflow that feeds the water-blocking sheet 3 into the sleeve 2. This control is achieved through a pressure stabilizing tank, ensuring stable transport of the water-blocking sheet 3 within the sleeve 2. Simultaneously, this application strictly controls the airflow velocity, ensuring that the production rates of the water-blocking sheet 3 and the sleeve 2 are similar, thus allowing the sleeve 2 to remain stably within the gap between the optical fiber 1 and the sleeve 2.

[0039] On the other hand, this application adjusts the extrusion die 8 of the sleeve 2 accordingly to facilitate the stable delivery of the water-blocking sheet 3 into the sleeve 2. Specifically, the extrusion die 8 of the sleeve 2 includes a die core 801 and a die cover 802, with an opening between the die core 801 and the die cover 802 for the sleeve 2 material to pass through; at the same time, a first channel 803 is reserved on the die core 801, the first channel 803 is located at the center of the die core 801, for the optical fiber 1 to pass through, and a second channel 804 is provided on the outer periphery of the first channel 803. The second channel 804 has a ring structure and is used for the transportation of the water-blocking sheet 3. One end of the second channel 804 is connected to the output end of the pressure stabilizing tank, and the other end is connected to the opening formed by the die core 801 and the die cover 802. By blowing air into the second channel 804, the water-blocking sheet 3 is brought into the extrusion die 8 of the sleeve 2.

[0040] More preferably, a third channel 805 is also provided on the outer periphery of the second channel 804 in this application. Simultaneously, multiple negative pressure adsorption holes are provided on the outer wall of the second channel 804. The third channel 805 is under negative pressure, allowing the water-blocking sheet 3 within the second channel 804 to adhere to the inner wall of the second channel 804 and be transported forward. It is worth noting that the airflow within the third channel 805 in this application is relatively weak. The airflow within the third channel 805 is adjusted and controlled through actual production. Its main purpose is to change the arrangement direction of the water-blocking sheet 3 within the second channel 804, so that the larger area side of the water-blocking sheet 3 adheres to the surface of the second channel 804.

[0041] Furthermore, the process of blowing in the water-blocking sheet 3 in this application is as follows: the sleeve 2 is produced by extrusion mold 8, the optical fiber 1 is introduced into the first channel 803, and the optical fiber 1 is produced together with the sleeve 2; the water-blocking sheet 3 is blown into the second channel 804, and the water-blocking sheet 3 fills the gap between the optical fiber 1 and the sleeve 2; the airflow velocity in the second channel 804 is adjusted so that the transmission rate of the water-blocking sheet 3 in the second channel 804 is similar to the production rate of the sleeve 2; negative pressure is drawn into the third channel 805 to adjust the arrangement of the water-blocking sheet 3 in the second channel 804.

[0042] Normally, the production rate of the sleeve 2 is 1.67~13.33m / s. When the conveying rate of the water blocking plate 3 in the second channel 804 is 1.5~12m / s, it is considered that the conveying rate of the water blocking plate 3 is the same as or similar to the production rate of the sleeve 2.

[0043] The following tests were conducted on the water-blocking performance of the all-dry optical unit in this application: Example 1: G.652D optical fiber 1 with 12 cores was selected and stranded. A sleeve 2 was prepared using modified polypropylene material with a diameter of 2.3 mm and a thickness of 0.35 mm. Water-blocking powder with a particle size of 60~150 μm and a filling rate of 18.5 mg / m was filled between optical fiber 1 and sleeve 2. Optical fiber 1 and water-blocking powder were directly blown into sleeve 2 to obtain sample 1.

[0044] Example 2: G.652D optical fiber 1 with 12 cores was selected and stranded. A sleeve 2 was prepared using modified polypropylene material with a diameter of 2.3 mm and a thickness of 0.35 mm. A water-blocking sheet 3 was filled between the optical fiber 1 and the sleeve 2. The length of the water-blocking sheet 3 was 60~150 μm, the aspect ratio of the water-blocking sheet 3 was 5~20:1, and the filling rate of the water-blocking sheet 3 was 18.5 mg / m. The optical fiber 1 and the water-blocking sheet 3 were directly blown into the sleeve 2 to obtain sample 2.

[0045] Example 3: G.652D optical fiber 1 with 12 cores was selected and stranded together. A sleeve 2 was prepared using modified polypropylene material with a diameter of 2.3 mm and a thickness of 0.35 mm. A water-blocking sheet 3 was filled between the optical fiber 1 and the sleeve 2. The length of the water-blocking sheet 3 was 60~150 μm, the aspect ratio of the water-blocking sheet 3 was 5~20:1, and the filling rate of the water-blocking sheet 3 was 18.5 mg / m. Sample 3 was prepared using the all-dry optical cable preparation process described in this application.

[0046] Three samples were selected from each sample group, each 3m in length. A water seepage test was conducted according to IEC 60794-1-22 standard. The time it took for the water column to stop moving and the distance it moved were recorded for each sample. The average value for each group of samples was obtained. The test results are as follows: Figure 4 As shown.

[0047] pass Figure 4 As shown in the data, it can be seen that compared with conventional water-blocking powder, the water-blocking sheet 3 in this application can expand rapidly after absorbing water and quickly seal the gap between the optical fiber 1 and the sleeve 2, which can significantly improve the water blocking efficiency; at the same time, the water-blocking sheet 3 can uniformly seal the gap between the optical fiber 1 and the sleeve 2, thereby improving the water blocking ability.

[0048] Furthermore, since this application has a faster water-blocking efficiency, the test time of the water seepage test can be appropriately reduced when the all-dry optical cable in this application is subjected to conventional water-blocking test, so as to improve the water-blocking test efficiency of the optical cable and accelerate the production efficiency of the optical cable.

[0049] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A completely dry optical unit, characterized in that, include: At least one optical fiber, the outer periphery of which is covered by a sleeve, and a gap is left between the optical fiber and the sleeve, the gap being filled with a water-blocking sheet; The water-blocking sheet is sheet-shaped, and the ratio of the length dimension of the water-blocking sheet to the width or thickness dimension of the water-blocking sheet is 5~20:

1. The specific surface area of ​​the water-blocking sheet is 0.09~0.8 / um.

2. The all-dry optical unit according to claim 1, characterized in that, The length direction of the water-blocking plate is consistent with the axial direction of the sleeve, and the filling rate of the water-blocking plate in the gap is 12~32mg / m.

3. The all-dry optical unit according to claim 1, characterized in that, The water-blocking sheet absorbs no less than 420 ml / g of water per minute.

4. The all-dry optical unit according to claim 1, characterized in that, The water-blocking sheet has a length dimension of 60~150μm.

5. A completely dry optical cable, characterized in that, Including the all-dry optical unit as described in any one of claims 1 to 4, the outer periphery of the sleeve is further provided with an outer sheath.

6. The all-dry optical cable according to claim 5, characterized in that, The water-blocking sheet is provided between the sleeve and the outer sheath, and part of the water-blocking sheet is attached to the inner wall of the outer sheath. The average concentration of the water-blocking sheet is not greater than 200 mg / m³.

7. A method for preparing an all-dry optical cable, used to prepare the all-dry optical cable as described in claim 5 or 6, characterized in that, Includes the following steps: Obtain the water-blocking substrate and cut it into water-blocking sheets using a shearing machine; The first screening is for water-blocking sheets with a size of 60~150μm, and the second screening is for water-blocking sheets with an aspect ratio or length-to-height ratio of 5~20:

1. The optical fiber is introduced into the sleeve, and the water-blocking plate is blown into the sleeve to obtain a fully dry optical unit. An outer sheath is extruded around the periphery of the all-dry optical unit to obtain an all-dry optical cable.

8. The method for preparing an all-dry optical cable according to claim 7, characterized in that, The secondary screening process of the water-blocking sheet is as follows: the water-blocking sheet is initially screened into spherical, sheet-like and irregular shapes using centrifugal separation technology, and sheet-like water-blocking sheets are selected; the sheet-like water-blocking sheets are classified using an air classifier, and water-blocking sheets with different aspect ratios or length-to-height ratios are air-blown and diverted to different regions, and water-blocking sheets with aspect ratios or length-to-height ratios of 5 to 20:1 are selected as the water-blocking material for the all-dry optical cable.

9. The method for preparing an all-dry optical cable according to claim 7, characterized in that, In this application, the water-blocking sheet is blown into the inside of the sleeve through a sleeve extrusion die, wherein the sleeve extrusion die includes: A mold core and a mold cover, wherein an opening for the sleeve material to pass through is formed between the mold core and the mold cover; The core has a first channel pre-reserved, which is located at the center of the core and is used for optical fiber to pass through; A second channel is provided on the outer periphery of the first channel. The second channel is arranged in a ring and is used to transport the water-blocking sheet. A third channel is also provided on the outer periphery of the second channel. The outer periphery wall of the second channel is provided with a plurality of negative pressure adsorption holes. The third channel is connected to the second channel through the negative pressure adsorption holes, and the second channel is under negative pressure.

10. The method for preparing an all-dry optical cable according to claim 9, characterized in that, The blowing of the water-blocking sheet includes the following steps: The sleeve is produced using a sleeve extrusion die, and the optical fiber is introduced into the first channel. The optical fiber is produced together with the sleeve. The water-blocking sheet is blown into the second channel, filling the gap between the optical fiber and the sleeve; the airflow velocity in the second channel is adjusted so that the transmission rate of the water-blocking sheet in the second channel is similar to the production rate of the sleeve. Apply negative pressure to the third channel and adjust the arrangement of the water-blocking plates in the second channel.

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