Expandable continuous filament

Abstract

A foamable filament composition comprising a single polymer or a blend of polymers and a foaming agent having a predetermined activation temperature, wherein the single polymer or blend of polymers has a molecular weight sufficient to allow entanglement of the polymer chains, and the single polymer or blend of polymers is melt-processable at a temperature below the predetermined activation temperature of the foaming agent.

Description

[Technical Field]

[0001] This instruction generally relates to foaming materials. More specifically, this instruction relates to polymeric filaments adapted to foam when exposed to a stimulus. [Background technology]

[0002] Foamed materials are useful for cushioning, energy absorption, and thermal insulation applications. Some foamed materials are compressible, allowing for energy dissipation, energy storage, or a combination of both. Foamed materials can enable stress distribution, contributing to improved comfort in applications such as seat cushions, mattresses, pillows, and some apparel items. Foamed materials in the form of filaments can be incorporated into fabrics by weaving, knitting, or other means, enabling foamed materials that conform to complex shapes and surface contours. When foamed filaments are formed integrally with other materials by weaving, knitting, printing, or other means, and then subjected to a foaming process, the foamed filaments adhere to themselves or to the other materials, resulting in a final composition that possesses the properties of both materials or a final composition that acts as a binder for non-adhesive developing materials.

[0003] The production of foamed filaments can present certain challenges. Specifically, while it may be desirable for the filament to be adapted to foam when exposed to heat, the foaming temperature must not be so high as to damage or stress any materials integrated with the filament. Furthermore, filaments may also foam during the extrusion process, which also requires heating; however, the extrusion temperature must be lower than the filament's foaming temperature to avoid premature foaming.

[0004] After the foaming process, the filament can form a foam with an open-cell configuration, a closed-cell configuration, or some combination of open and closed cells. The term "closed-cell" refers to a foam structure where the gas-filled chambers or cells are completely sealed by the polymer material with no connectivity between cells and no or very slow gas exchange between cells. The term "open-cell" refers to a foam structure where the cells are connected by pathways that allow for a relatively unrestricted flow of gas between cells. Both types of foams can provide cushioning and energy absorption, but they function by slightly different mechanisms. Closed-cell foams primarily exhibit cushioning through the compression of gas trapped within the closed cells of the foam, with the cells functioning as micro-airbags or air springs. As such, closed-cell foams under sustained load and high temperatures are prone to compression set due to gas escaping or emitting from the cells when the foam is compressed and / or exposed to high temperatures over a long period of time.

[0005] Open-cell foams can also provide cushioning and energy absorption. However, the cushioning and energy absorption properties of open-cell foams are governed not by the compression of gas within the cells, but by the properties of the polymer material constituting the cell walls of the polymer cell foam material. By appropriately selecting the elastic modulus and degree of porosity of the polymer or polymer compound forming the cell walls, the foam material can be made more easily compressible or more compressively resistant.

[0006] The compressibility of cellular foams can also be controlled through the cured density of the foam material. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] This instruction relates to polymers or polymer formulations that can be kneaded and formed into filaments or fibers (comprising a single composition or multiple compositions), the filaments of which can be incorporated into manufactured articles and subsequently foamed. The resulting foamed structure may be substantially open-celled. The resulting foamed structure may be substantially closed-celled. The hardness of the foamed structure may be highly controllable through the selection of polymer compositions for the cell wall material and through the control of the final foam density. [Means for solving the problem]

[0008] The teachings herein are directed toward foaming filament compositions comprising a single polymer or polymer compound and a foaming agent having a predetermined activation temperature. The single polymer or polymer compound has a molecular weight sufficient to allow entanglement of polymer chains, and the single polymer or polymer compound can be melt-processed at a temperature well below the predetermined activation temperature of the foaming agent in order to avoid foaming activation during filament formation in order to form the resulting filament.

[0009] A single polymer or polymer compound may be selected from the group comprising: ethylene octene copolymer, thermoplastic polyurethane, ethylene propylene diene monomer rubber, styrene-isoprene block copolymer, poly(styrene-butadiene-styrene), styrene-ethylene-butylene-styrene, nitrile rubber, styrene-butadiene rubber, or a combination thereof.

[0010] Single polymers or polymer formulations may be melt-processable at temperatures below 204.4°C (400°F), below 176.7°C (350°F), below 148.9°C (300°F), or even below 104.4°C (220°F). The single polymer or polymer formulation may have a density of approximately 0.7 g / cm³. 3 ~Approximately 0.99 g / cm³ 3It may comprise ethylene octene having an uncured density of. A single polymer or a blend of polymers may each have an uncured density of about 0.7 g / cm 3 to about 0.99 g / cm 3 It may comprise a blend of at least two ethylene octene polymers having an uncured density of. A single polymer or a blend of polymers may have an uncured density of about 0.5 g / cm 3 to about 1.5 g / cm 3 It may comprise a rubber or a blend of rubbers having an uncured density of. The resulting filament may have a post-foaming density of about 0.01 g / cm 3 to about 1.5 g / cm 3 The resulting filament may have a post-foaming density of about 0.1 g / cm 3 to about 0.5 g / cm 3 The resulting filament may have a post-foaming density of.

[0011] The resulting filament may have an Asker C foam hardness of about 1 to about 100. The resulting filament may have an Asker C foam hardness of about 5 to about 60. The resulting filament may have an Asker C foam hardness of about 20 to about 60. The resulting filament may have an Asker C foam hardness of about 40 to about 65. The resulting filament may have an average cell size post-foaming of about 0.1 mm to about 2.0 mm. The resulting filament may have an average cell size post-foaming of about 0.2 mm to about 0.4 mm. The resulting filament may have an average cell size post-foaming of about 0.3 mm to about 2.0 mm.

[0012] The predetermined activation temperature of the foaming agent may be about 110°C to about 200°C. The predetermined activation temperature of the foaming agent may be about 135°C to about 160°C.

[0013] The resulting filament may have a diameter in the range of about 0.1 mm to about 1.5 mm. The resulting filament may have a diameter in the range of about 0.8 mm to about 1.2 mm.

[0014] The resulting filament may be woven with one or more additional filaments having the same composition as the resulting filament. The resulting filament may be woven with one or more additional filaments having a different composition from the resulting filament. The resulting filament may be at least partially or substantially an open-cell material.

[0015] The composition may contain particulate matter. The composition may contain particulate matter, which has a diameter between 1 / 5 (1 / 5) of the diameter of the unfoamed filament and 1 / 20 (1 / 20) of the diameter of the unfoamed filament. The composition may contain particulate matter, which has a diameter less than 1 / 20 (1 / 20), less than 1 / 100 (1 / 100), or even less than 1 / 1000 (1 / 1000) of the diameter of the unfoamed filament.

[0016] A single polymer or polymer compound may have a softening or melting point of less than 120°C, less than 100°C, or less than 80°C.

[0017] The foaming agent may be a chemical foaming agent. The single polymer or polymer formulation includes metallocene-catalyzed polymerization copolymers of ethylene and higher molecular weight olefin monomers selected from propylene, butene, hexene, and octene. The composition may contain copolymers having a melt index less than 5 g / 10 min. The composition may contain copolymers of ethylene having a melt index greater than 20 g / 10 min.

[0018] The composition may contain one or more copolymers selected such that the Asker C hardness of the foamed composition is less than 40. The composition may contain one or more copolymers selected such that the Asker C hardness of the foamed composition is less than 30.

[0019] The water absorption rate of the composition in weight percent can be from about 0.2 to about 1.2. The compression set of the composition, measured according to ASTM D3574-17 Test D, can be a change of 10% to 15% at 21°C. The compression set of the composition, measured according to ASTM D3574-17 Test D, can be a change of 28% to 32% at 43°C. The compression set of the composition, measured according to ASTM D3574-17 Test D, can be a change of 30% to 38% at 54°C.

[0020] The amount of blowing agent utilized can be from about 0.5 wt% to 4 wt%. A physical blowing agent can be utilized such that the expanded composition has a matte finish. During extrusion, the filament can have a die swell ratio percentage of less than 100%, less than 80%, less than 60%, less than 40%, or less than 20%.

[0021] The composition can comprise a single polymer or blend of polymers and a blowing agent. The filament itself can comprise a single polymer or blend of polymers and a blowing agent. The composition can be extruded or spun into filaments at a temperature higher than the melting point of the polymer or polymer blend but lower than the predetermined activation temperature of the blowing agent. The foamable filament can be activated by heat or another stimulus to form a foamed material. The hardness and compressibility of the resulting foam structure can be adjustable based on the polymer selection and level of foaming.

[0022] The teachings herein are further directed to a foamable filament composition comprising a single polymer or blend of polymers and a blowing agent having a predetermined activation temperature. The single polymer or blend of polymers can have a molecular weight sufficient to allow entanglement of the polymer chains. The single polymer or blend of polymers can be melt processable at a temperature lower than the predetermined activation temperature of the blowing agent in forming the resulting filament.

[0023] The teachings of this specification further contemplate a method of manufacturing the compositions described herein, the method comprising the steps of melt blending the composition and extruding the composition to form a foamed filament. The teachings are also directed to a method comprising the steps of sewing a fabric using the foamed filaments described herein and foaming the filaments after sewing. The teachings of this specification also contemplate the use of the foamed filaments described herein for weaving, knitting, inlaying, crocheting, braiding, 3D printing, or non-woven fabric making.

Brief Description of the Drawings

[0024] [Figure 1] Cross-sectional views of the filament according to the present teachings, before and after foaming, are shown.

Modes for Carrying Out the Invention

[0025] The explanations and illustrations presented in this specification are intended to familiarize those skilled in the art with the invention, its principles, and its practical applications. Accordingly, the specific embodiments of the present disclosure shown are not intended to be exhaustive or to limit the invention. Therefore, the scope of the invention should be determined not by reference to the above description, but instead by reference to the appended claims and the full scope of equivalents to which such claims are entitled. The disclosures of all papers and references, including patent applications and patents, are incorporated by reference for all purposes. Further, other combinations that may be derived from the appended claims are possible, and such combinations are also hereby incorporated by reference into this written description.

[0026] The teachings herein are directed toward polymer filaments for use in the construction of one or more of the following: textiles, footwear, sporting goods and accessories, furniture, outdoor fixtures, or vehicle interiors. The filaments may be woven together with additional filaments of similar composition, or with filaments of different composition. The filaments may be used as a means of joining one or more materials or surfaces, or as a means of providing a decorative surface. The filaments may be formed into mesh materials.

[0027] A foaming filament composition may comprise a single polymer or a polymer formulation and a foaming agent (e.g., a foaming agent). Polymers suitable for use in the invention may be available as solid materials, non-blocking pellets, chunks, crumbs, bales, or pieces. Polymers or polymer formulations may include, but are not limited to, thermoplastic polyurethanes, elastomers, polyamides, polyesters, styrene block copolymers, and polyolefins. Styrene block polymers may include block copolymers of styrene with isoprene, butadiene, ethylenebutylene, ethylenepropene, or any combination thereof. Specific block copolymers of styrene suitable for use in the filaments described herein are available under the trademark name Kraton. Suitable examples of polyolefins may include copolymers of ethylene containing EPDM elastomers (examples available under the trademark name Nordel), and copolymers of ethylene with polar monomers such as vinyl acetate, methyl acrylate, or butyl acrylate. Suitable ethylene copolymers are available under the trademark names Elvax, Elvaloy, Evatane, Lotryl, Orevac, or Ateva from Dow, Arkema, and Celanese.

[0028] Filaments can be formed by extruding a polymer or polymer compound alone. Filaments can also be formed by extruding a foamed material together with a non-foamed filament. It is also possible to make the filament a two-component fiber. The foamed portion may be inside the filament, outside the filament, or both. Optionally, both components may be foamed. Two-component filaments can be formed by drawing the formed filament through a foamed material (either inside or outside). Two-component fibers can be produced by co-melt extrusion through a die. For example, a process similar to polymer coating on electric wires may be used. To avoid slippage during the manufacturing process or for UV resistance, it may be desirable to include the foamed material inside the two-component fiber.

[0029] It is also possible to incorporate one or more components of a two-component filament to provide strength and rigidity to the combination of components, thereby making the filament less susceptible to stretching or breakage in subsequent processing steps such as weaving or knitting. When the use of a single-component foamed filament is essential or desirable, the foamed filament may preferably have a high modulus of elasticity and a high tensile stress at break to allow for secondary processing of the filament within the article.

[0030] Examples of selected compositions for filaments formed from polymers or polymer formulations described herein are shown in Table 1.

[0031] [Table 1]

[0032] The extrusion characteristics, foam cell size, and anchor C value for the examples from Table 1 are shown in Table 2 below.

[0033] [Table 2]

[0034] Table 3 shows the various physical properties of the examples from Table 1.

[0035] [Table 3]

[0036] Considering Examples 1-9 and their corresponding properties presented in Tables 2 and 3, it is observed that the material selected for forming a foamed filament may be chosen such that specific desired properties and characteristics are exhibited before and / or after foaming. The selected properties and characteristics may depend on whether the filament is formed as a single fiber or as a two-component fiber, how the filament is incorporated into the final article, the function of the article into which the foamed filament is incorporated, and the properties that the foamed filament is expected to impart to the finished article.

[0037] In one non-limiting embodiment, when the filament is used as a single-component filament, the foamed filament from Example 1, based on a thermoplastic polyurethane polymer, may be preferred due to its high modulus of elasticity and stress at break before activation. Other filaments with lower modulus of elasticity and stress at break would need to be processed as a two-component fiber with a second component to supplement stiffness and strength.

[0038] The thermoplastic polyurethane filament of Example 1 and the styrene-butadiene filament of Example 9 result in post-activated cell foams with small, uniform cell sizes. Small, uniform cell sizes are preferred for sealing applications because the numerous small cells provide more winding pathways for the intrusion of foreign matter such as water. Small, uniform cell sizes are also known to improve certain mechanical properties of foam materials. While Examples 1 and 9 provide this similarly small, uniform cell size, they offer very different softness values ​​as measured by the Asker C hardness scale. Example 1 has a fine cell size with an Asker C hardness of 80, while the filament of Example 9 has an Asker C hardness of 13. Each of these materials can be selected depending on the specific intended use of the filament.

[0039] The butadiene elastomers of Examples 8 and 9, prepared as nitrile butadiene rubber and styrene butadiene rubber, respectively, are both very soft and yield an Asker C value of 13 or less. The types of soft foams demonstrated in Examples 8 and 9 may be suitable for applications requiring cushioning and comfort. In addition, nitrile elastomers are known to have excellent resistance to non-polar fluids such as gasoline, diesel fuel, and motor oil. As such, the foamed filament of Example 8 may be useful in applications where exposure to these types of fluids may occur.

[0040] The thermoplastic polyurethane filament of Example 1 and the filament of Example 7, based on the ethylene octene copolymer formulation, exhibit very low die swell, making it feasible to produce small-diameter filaments with less need to stretch the material during filament extrusion.

[0041] The filament of Example 7 offers a balance of properties with a moderate cell size, softness, and tensile stress at fracture. The ethylene octene copolymer-based filament offers other inherent attributes, such as the ability to adjust hardness, and other attributes of filaments based on this technology are presented in more detail below.

[0042] It should be noted that not all polymer formulations can be processed into filaments less than 1 mm thick, as demonstrated in Examples 4 and 5. This may be due, at least in part, to higher viscosity and / or molecular weight. Example 5, compared to the other compositions, was processed at 90°C and 300 s. ?1 It exhibited higher viscosity. Example 4, with its relatively low viscosity, was converted to a film of approximately 1.5 mm, but not to a film of less than 1 mm. Imperfect material compatibility can lead to non-uniform extruded materials, including potentially high die swells.

[0043] All examples in Table 1 are fully or nearly fully activated with an exposure time of approximately 15 minutes at a temperature of 157.2°C (315°F). Samples incorporating the blowing agent activator are fully or nearly fully activated with an exposure time of approximately 12 minutes (in a convection oven) at a temperature of 140.6°C (285°F). Alternatively, activation can occur in a shorter time within a heated platen or other rapid heating device. For materials containing the blowing agent activator, at least partial activation can be achieved at lower temperatures of approximately 135°C (275°F) or less. When incorporated into other articles, the time and temperature required for full activation may vary depending on the size and shape of the article, where the foaming filament is incorporated into the article, and how heat is applied. For example, if the foaming filament is located inside the article and insulated from the surface, a higher temperature or longer time may be required to achieve full activation. Furthermore, all examples in Table 1 except Example 5 can be extruded into filaments at die temperatures of 98.9°C (210°F) or lower. This results in a significant difference between the temperature required to process the foaming material into a filament without undesirable premature activation of the foam and the temperature required for complete or near-complete activation.

[0044] As described herein, filaments may be adapted to foam (e.g., activate) when exposed to stimuli (e.g., heat, induction, microwave, UV light, moisture, etc.). Prior to foaming, the filament may be soft to the touch and / or inherently flexible, while still providing sufficient strength for use when sewing materials as described herein. One or more of these properties may be maintained after foaming.

[0045] When using such activatable materials, it is certainly desirable that the processing temperature of the material (e.g., the temperature at which the material is manufactured and applied) is relatively low. Among other advantages, a low processing temperature reduces the burden on manufacturing. It is advantageous if the processing temperature is much lower than the specified activation temperature (for example, at least 4.4°C (40°F) lower, at least 15.6°C (60°F) lower, or even at least 26.7°C (80°F) lower).

[0046] To avoid premature activation of the material, it is preferable that the material has a sufficiently low viscosity at the temperature at which filament formation occurs, in order to knead and process the foaming composition into a foaming filament at a sufficiently low temperature. For example, the polymer composition is 300s -1 Furthermore, the viscosity measured by a capillary rheometer at 90°C may preferably be about 4000 Pa.s or less, preferably 3000 Pa.s or less, and more preferably 2500 Pa.s or less. Alternatively, the polymer composition may be 1000s ?1 Furthermore, the viscosity, as measured by a capillary rheometer at 90°C, may preferably be about 2500 Pa.s or less, preferably 1500 Pa.s or less, and more preferably 1000 Pa.s or less. If the polymer is shear-reducing, it may be beneficial to achieve the viscosity required for improved processing.

[0047] To obtain a sufficiently low viscosity at the target filament formation temperature, it is desirable that the polymer material be processed above its softening point for amorphous materials, or slightly above its melting point for crystalline materials. Therefore, it may be desirable for the polymer material to have a relatively low softening or melting point. At the same time, the fusion temperature should not be so low that the filament aggregates or fuses at ambient temperature. For example, suitable polymer materials may have softening or melting points of less than or about 120°C, less than or about 100°C, or even less than or about 80°C. The softening point can roughly correspond to the glass transition temperature of amorphous materials (e.g., polymer formulations), as reported in Table 3. This result is not unexpected, as the glass transition temperature corresponds to a change in the free volume of the polymer that allows for an increase in relative molecular motion.

[0048] Furthermore, it may be desirable for the foamed filament to be substantially thin. For example, it may be desirable for the foamed filament to be formed with a diameter of 1 mm or less. To form a thin-diameter filament, it may be necessary for the extruded material to have minimal or low die swell. Die swell is the result of the orientation and entanglement of residual polymer as the molten material passes through the die. Entropy-driven forces can return the polymer components to their pre-extrusion state, resulting in changes in the post-extrusion thickness of the extruded filament. Therefore, to minimize die swell and obtain a thin filament, polymers with lower intrinsic viscosity, lower molecular weight, and consequently lower polymer entanglement may be preferable. This is observed in Table 3, where the main polymers of Examples 1 and 7, which have high thermoplasticity and low molecular weight, have low die swell of 15% or less. In contrast, the higher molecular weight elastomer polymers, which are the main polymers of Examples 8 and 9, have high die swell of over 70%.

[0049] To process foamed filaments into articles by methods such as weaving, knitting, or crocheting, the composition of the filament may be selected to have a low coefficient of friction so that the filament slides easily on itself. Friction can be reduced to some extent by incorporating internal lubrication agents or by treating the filament externally with lubrication agents; however, certain characteristics such as surface roughness may not be adequately compensated by these treatments and may adversely affect the processing of the filament. One cause of surface roughness in extruded articles is melt fracture. Melt fracture is a result of shear stress occurring during the extrusion process. One way to reduce the shear stress that causes melt fracture is to process at a higher temperature. However, this method cannot be used with heat-activatable materials due to the risk of premature activation of the material during filament formation. Therefore, the composition of the filament may be selected to have a sufficiently low viscosity at the target processing temperature in order to avoid the shear stress that causes melt fracture.

[0050] The foaming filament composition may contain one or more additives for viscosity modification. For example, the additives may be selected to reduce the viscosity of the composition to facilitate processing. The viscosity modifier may be a liquid. Liquid viscosity modifiers may be petroleum-based paraffinic processing oils. Suitable oils are available under the trademark Sunpar from Holly Frontier Refining and Marketing, LLC, or under the trademark ParaLux from Chevron USA, Inc. Alternatively, the viscosity modifier may be a low molecular weight, high melt index polymer or copolymer. Low molecular weight polymers may typically have a melt index of at least 400, preferably 800 or higher (measured at 190°C and 2.16 kg / kg according to ASTM D1238). Suitable grades are available under the trademark Affinity GA from Dow. Ethylene vinyl acetate copolymers and ethylene acrylate copolymers are also available that meet these criteria and are suitable for use as taught herein. Alternatively, viscosity can be reduced by incorporating wax. Viscosity-modifying additives are typically added at levels of 10% by weight or less, more preferably 5% by weight or less, when used. Low molecular weight additives, whether liquid or solid, can function to plasticize the foaming filament composition before and / or after the foaming process.

[0051] The foaming filament composition may contain a thermally activated physical or chemical foaming agent. The foaming agent may be selected to remain substantially unchanged during the mixing and formation of the foaming filament, but to change size or release gas at a temperature close to or at the foaming temperature of the filament. The foaming agent may preferably remain substantially unchanged up to a temperature of about 100°C, but may begin to foam or release gas at a temperature of about 110°C or even further at about 135°C. Examples of physical foaming agents suitable for use in the invention are available under the trademark name ExpanseL, available from Nouryon, Inc. The composition may contain a chemical foaming agent. The chemical foaming agent may be an endothermic or exothermic foaming agent. Endothermic foaming agents absorb heat from the matrix during activation, while exothermic foaming agents release heat. Endothermic foaming agents include metal salts of carbonate and bicarbonate ions. Endothermic foaming agents suitable for use in the present invention are available under the trademark names Kycerol from Rit-Chem and Hydrocerol from Clariant. The foaming filament composition may contain an exothermic foaming agent. Exothermic foaming agents suitable for use in the invention include dinitrosopentamethylenetetramine, azodicarbonamide, p-toluenesulfonyl hydrazide, or p,p'-oxybis(benzenesulfonyl hydrazide).

[0052] The type and amount of foaming agent may be selected based on the desired activation temperature and the desired level of volume increase (or density decrease) for foaming the filament. For example, p,p'-oxybis(benzenesulfonyl hydrazide) may be selected as a foaming agent when a low to moderate foaming temperature (temperatures in the range of about 135°C to about 160°C) is desired. The amount of foaming agent depends on the type of foaming agent used and the desired level of volume increase, but is typically in the range of about 0.2% to 15% by weight, or even 1.5% to 6% by weight, of the total filament composition.

[0053] Optionally, foaming activators may be used to lower the onset temperature of gas release from the foaming agent. The amount and type of activator may depend on the type of chemical foaming agent (e.g., blowing agent) used. For azodicarbonamide blowing agents, zinc oxide and zinc or calcium salts may function as activators. A suitable activator for azodicarbonamide blowing agents is the zinc salt of benzenesulfonic acid. A suitable activator for p-toluenesulfonyl hydrazide and / or p,p'-oxybis(benzenesulfonyl hydrazide) is urea. When used, the foaming activator will typically be less than 5% by weight, preferably less than 3% by weight, and more preferably less than 1% by weight of the total foaming filament composition.

[0054] When a filament is to be foamed after being incorporated into an article containing a heat-sensitive material, it is desirable to lower the activation point of the foaming process by selecting a foaming agent with a low activation temperature or by adding a foaming agent activator. A lower activation temperature allows activation without degradation such as melting, warping, oxidation, or discoloration of other components of the article containing the filament. For example, filaments with a lower activation temperature can be used with a wider range of materials. This is particularly important when combined with non-synthetic fibers, fabrics, and textiles. Specific examples include cotton, wool, flax, silk, bamboo, polyester, rayon, nylon, spandex, and other textiles frequently used in clothing, footwear, bedding, and sporting goods.

[0055] The ability to produce foaming filaments with low activation temperatures presents specific challenges in terms of the need for lower viscosity to efficiently and effectively produce fine filaments without causing premature activation of the foaming agent. In non-activatable systems, raising the temperature is a common technique to lower viscosity and increase throughput or to eliminate die swell or melt fracture problems, as discussed above. The materials in the current teachings can be selected to have sufficiently low viscosity at a temperature that allows them to be processed into filaments without causing premature activation of the foaming agent. The low viscosity required to meet these challenging processing requirements is achieved through the selection of inherently low viscosity materials, through carefully selected additives, or through a combination of these techniques. The materials in the current teachings can also maintain sufficiently low activation temperatures so that the foaming process can occur without causing damage to other components used with the foaming filament. This is important because, although foaming filaments are expected to be more likely to be used as a single component in assemblies or structures, foaming filaments may be used alone or in combination with other foaming filaments as desired.

[0056] When a matte or non-glossy finish is desired for activated and expanded filaments, a physical foaming agent (e.g., a foaming agent) or a combination of physical foaming agents may be used. As one non-limiting example, a physical foaming agent may act to matte the surface due to the fact that foaming agent spheres on and just below the surface expand and deflect light into a random pattern. The amount of foaming agent required for the matting purpose may be about 0.5% to 4% by weight.

[0057] Certain polymer materials that can be used in accordance with the teachings herein include metallocene-catalyzed polymerization copolymers of ethylene and higher molecular weight olefin monomers such as propylene, butene, hexene, and octene. Products of this type that are suitable for use in accordance with the teachings herein are available under the trademark names Engage, Versify, and Affinity from Dow Polymers, and ExxonMobile, under the trademark name Exxact. The polymer component typically constitutes about 50% to about 90% or more by weight, preferably between 60% and 80% by weight, of the foaming filament composition.

[0058] The foaming filament composition may optionally include a thermally activated crosslinking agent capable of creating bonds between individual polymer chains. Similar to thermally activated foaming agents, the thermally activated crosslinking agent remains unreacted until the temperature used for kneading and forming the foaming filament composition, for example, 100°C or higher. The thermally activated crosslinking agent may react to crosslink the polymer at a temperature close to or above the activation temperature of the foaming agent. The thermally activated crosslinking agent may be an organic peroxide having a very long half-life at room temperature but a substantially shorter half-life at high temperatures. Suitable organic peroxides for use in the invention include, but are not limited to, dicumyl peroxide, di(ter-butylperoxyisopropyl)benzene, butyl 4,4-di(ter-butylperoxy)valerate, ter-butylperoxybenzoate, or 1,1-di(ter-butylperoxy)-3,3,5-trimethylcyclohexane. The organic peroxide may be used neat or supplied on a support. Suitable organic peroxides are available under the trademark names Trigonox and Perkadox from Nouryon, and under the trademark names Luperox, Dicup, and Vulcup from Arkema. When used neat or on a support, the active organic peroxide may typically be present in an amount of less than 5%, preferably less than 4%, and more preferably less than 1%, of the total weight of the foaming filament composition. Any composition incorporating a crosslinking agent may be more stable at high temperatures after the activation and foaming process, and may have a reduced tendency to deform or flow upon subsequent reheating when incorporated into an article that is washed with hot water and dried using heat, for example. Thermally activated crosslinking agents may help the filament trap gas during the activation of the foaming agent. Thermally activated crosslinking agents may further help improve certain properties of the foaming filament material in the foamed state, such as improved strength or improved abrasion resistance.

[0059] Foaming filaments may preferably be free of thermally activated curing agents due to the odor caused by the curing agent. Furthermore, materials that remain substantially thermoplastic throughout the foaming process, i.e., materials that do not contain crosslinking agents, may be easier to recycle if necessary or desirable.

[0060] The foaming filament composition may optionally contain crosslinking aids. These aids function to increase the degree of crosslinking in the system and may further reduce the time and temperature required for crosslinking to occur. Suitable compounds as aids typically have carbon-carbon double bonds that readily react with free radicals generated by organic peroxide crosslinking agents. Aids can be monofunctional (containing one double bond), difunctional (containing two double bonds), or polyfunctional (containing three or more double bonds). The double bonds may exist as vinyl groups, allyl groups, acrylates, or methacrylates. Aids can be liquid or solid. One suitable aid is available under the trademark name Dymalink from Cray Valley. When used, aids typically exist in amounts of less than about 5%, or even less than about 3%, of the total weight of the foaming filament composition.

[0061] The foaming filament composition may optionally contain one or more inert particulate components. Such inert particulates may physically interact with the rest of the composition but will not chemically react with other components of the foaming filament composition. Particulate components may modify the properties of the foaming filament. For example, particulate components may increase the apparent modulus of the polymer components of the foaming filament composition. They may reduce the tactile stickiness of the formed fibers or filaments and affect the surface gloss. Useful particulate components include, but are not limited to, talc, feldspar, wollastonite, mica, clay, or limestone. The maximum particle size of the particulate components that can be used may be limited by the diameter of the filament to be produced. Preferably, the diameter of the particulate components is less than 1 / 20 of the diameter of the unfoamed filament, more preferably less than 1 / 1000 of the diameter of the unfoamed filament.

[0062] Other optional additives to the foaming filament composition include dyes, pigments, hydrocarbon resins, antioxidants, UV absorbers, light stabilizers, and flame retardants. Improved UV resistance can be achieved by adding additives, but for applications requiring a high degree of UV resistance, it may be preferable for the polymer composition to be based solely on or primarily on aliphatic polymer materials, without any aromatic polymers or additives.

[0063] The hardness of the resulting foamed filament composition may be adjusted and can be readily measured and compared by mechanical testing using an Asker durometer or by measuring load displacement. This is specifically demonstrated using ethylene octene copolymer. Hardness can be readily adjusted by selecting crystallinity which can be correlated with the density of one or more metallocene copolymers in combination with the amount of volume expansion during foaming. The filaments of the examples were formed using the components listed in Table 4 below, and the associated density and Asker C foam hardness were measured using the results shown in Table 1. The melt indices shown in Table 4 for various ethylene octene-containing compositions were measured according to ASTM 1238 (2.16 kg by weight at 190°C).

[0064] [Table 4]

[0065] For example, a foamable filament composition that provides an Asker C hardness of 45±5 after foaming can be obtained by using two ethylene octene copolymers with densities of 0.885 and 0.864 in a ratio of approximately 3:1 and a volume increase of 350%. For comparison, a foamable filament composition that provides an Asker C hardness of 20±5 after foaming can be obtained by using the same ethylene octene copolymers with densities of 0.885 and 0.864 in a ratio of approximately 1:2 and a volume increase of 500%.

[0066] Water absorption rates were also measured to determine the water absorption of various filaments after activation (post-baking at 140.6°C (285°F)). The results are shown in Table 5 below. The following tested materials are at least partially or substantially open-cell foams, but still exhibit minimal water absorption.

[0067] [Table 5]

[0068] Table 5 shows the water absorption data for foamed filament materials prepared according to the teachings herein, along with a comparison to commercially available closed-cell foam material L-2803 from L&L Products, Inc. The tests were conducted after foaming both products at appropriate times and temperatures.

[0069] [Table 6]

[0070] Table 6 compares the compression set of the foamed filament material according to this instruction with that of the closed-cell L-2803 material referenced in Table 5. The compression set was measured according to ASTM D3574-17 Test D.

[0071] It is desirable that the foamed filament consists of a small, uniform cellular structure. Closed-cell foams with a uniform cellular structure are known to have improved mechanical properties. In the case of open-cell foams, a finer cellular structure creates more winding pathways for the intrusion of foreign substances such as water.

[0072] The foamed filament composition can be mixed in a common melt-mixing facility such as a Banbury or Shaw internal rubber mixer or a Sigma-blade double-arm mixer. Preferably, the material is mixed in a continuous process such as a twin-screw extruder or a single-screw extruder with a mixing element incorporated into the screw design. The twin-screw extruder may rotate in opposite directions or co-rotate. The processing conditions must be selected to maintain a temperature close to or slightly above the melting point of the polymer components, but lower than the activation temperature of either the foaming agent or, if present, the crosslinking agent. When produced in batches, the foamed filament composition is converted into pellets or chunks for subsequent processing into filaments. The material can be formed into pellets or shredded into irregular pieces through underwater pelletizing or strand pelletizing operations. It may also be formed by sheet formation and subsequent cutting. When produced in a continuous mixing process, the material can be converted directly into filaments through a die having one or more openings to form the filaments, or it can be converted into pellets for subsequent processing into filaments.

[0073] The foamed filament composition can then be converted into filaments using a single-screw extruder fitted with an extruder die. The single-screw extruder provides efficient pumping of the polymer molten material with minimal surging, resulting in the ability to produce a consistent filament diameter. Processing may occur at or slightly above the melting or softening point of the polymer and below the activation temperature of the blowing and crosslinking additives. The extruder die may have a single opening to provide a single filament, or multiple openings to provide multiple filaments that can be wound or bundled separately for further processing. The filament diameter according to this teaching may be in the range of 0.1 mm or less to 1.5 mm or more, preferably between 0.8 mm and 1.2 mm.

[0074] The foamed filaments described herein can be formed into fabrics or articles by conventional methods such as weaving, knitting, crocheting, braiding, various nonwoven methods, or 3D printing, or can be used as part of nonwoven products. Alternatively, the foamed filaments can be inlaid into existing cloths or fabrics. Following the formation of articles of desired size and shape, the foamed filaments can be activated to foam and optionally crosslink. The foamed filament composition can be activated to form its foamed structure at a moderate temperature. Preferably, the temperature at which the filament foams is below 165°C, more preferably below 150°C, and even more preferably below 140°C. The temperature at which the material foams is controlled by the selection of a foaming agent, a foaming agent activator if used, and a crosslinking agent if desired. Matching the polymer melt and viscosity as a function of temperature characteristics to the foaming agent decomposition temperature can support the production of desirable foamed filaments.

[0075] When foamed, the density of the filament composition becomes approximately 1 g / cm³. 3 ~Approx. 0.25g / cm 3 The concentration decreases to 0.05 g / cm³, depending on the type and amount of foaming agent used, and combined with the polymer rheology of the decomposition temperature range. 3 The following reductions are possible. The resulting foam structure may be at least partially or substantially open-cell. This is evident from the rapid and easy release of gas from the bubbles when the foam is compressed, and is observed by bubble formation when the foam is compressed in water.

[0076] Figure 1 shows cross-sectional views of a polymer foam filament before and after activation as an example. The single polymer or polymer formulation 10 shown before activation contains a plurality of foaming agent particles 12 before the activation of the foaming agent. After activation, the single polymer or polymer formulation 10 contains trapped gas bubbles 14 formed as a result of the activation of the foaming agent.

[0077] Any numerical value described herein includes all values ​​from the lowest to the highest value in increments of one unit, provided that there is at least a two-unit gap between any lower and higher value. For example, if the amount of a component or the value of a process variable, such as temperature, pressure, or time, is stated to be between 1 and 90, preferably 20 and 80, and more preferably 30 and 70, then values ​​such as 15 and 85, 22 and 68, 43 and 51, and 30 and 32 are explicitly listed herein. For values ​​less than 1, one unit is considered to be correspondingly 0.0001, 0.001, 0.01, or 0.1. These are merely examples of what is specifically intended, and all feasible combinations of numerical values ​​between the lowest and highest values ​​listed are considered to be expressly stated in this application in a similar manner. As can be seen, the teaching of quantities expressed as “parts by weight” in this specification is also intended to be expressed in terms of weight percent for the same range. Accordingly, the range expression in the term “x parts by weight of the resulting polymer composition” in the detailed description of the invention is also intended to be taught the range of the same quantity as “x in weight percent of the resulting polymer composition.”

[0078] Unless otherwise stated, all ranges include both endpoints and all numbers between the endpoints. The use of "approximately" or "roughly" in relation to ranges applies to both ends of the range. Therefore, "approximately 20-30" is intended to cover "approximately 20-30" including at least the specified endpoint.

[0079] All disclosures in papers and references, including patent applications and patent publications, are incorporated by reference for any purpose. The term “essentially consisting of ○○” used to describe a combination includes the identified element, raw material, component, or process, as well as other such elements, raw materials, components, or processes that do not substantially affect the basic and novel characteristics of the combination. The use of the terms “comprising ○○” or “containing ○○” used herein to describe a combination of elements, raw materials, components, or processes also assumes embodiments that essentially consist of or further consist of such elements, raw materials, components, or processes. The use of “may” as a translation of “may” in this specification, such as “may include” or “may include”, is intended to indicate that any attribute described as “may include” or “may include” is optional.

[0080] Multiple elements, raw materials, components, or processes may be provided by a single, integrated element, raw material, component, or process. Alternatively, a single, integrated element, raw material, component, or process may be divided into multiple separate elements, raw materials, components, or processes. The disclosure "a" or "one," which is the translation of "a" or "one" in the original text for describing an element, raw material, component, or process, is not intended to exclude additional elements, raw materials, components, or processes. All references in this specification to elements or metals belonging to a particular group refer to the Periodic Table of Elements published and copyrighted by CRC Press, Inc. in 1989. Any reference to one or more groups is to the group as it is reflected in this Periodic Table of Elements using the systematic method of group numbering according to IUPAC.

[0081] It should be understood that the amounts of concentrates or dilutions described herein may be used. Generally, the relative ratios of the listed ingredients will remain the same. For example, if the instruction specifies 30 parts by weight of component A and 10 parts by weight of component B, it will be understood by those skilled in the art that such instruction also constitutes instruction to use components A and B in a relative ratio of 3:1. The concentration instruction in the examples may vary within approximately 25% (or more) of the stated value, and similar results can be expected. Furthermore, such compositions in the examples can be successfully adopted in the present method.

[0082] It will be understood that the above description is for illustrative purposes only and not intended to impose any limitations. Those skilled in the art will find many embodiments and applications beyond those provided to be obvious upon reading the above description. Therefore, the scope of the teachings should not be determined by reference to the above description, but rather by reference to the accompanying claims and the full scope of the equivalents to which such claims are entitled. All disclosures in papers and references, including patent applications and patent publications, are incorporated by reference for all purposes. The omission of any aspect of the subject matter disclosed herein in the accompanying claims shall not be construed as a rejection of such subject matter or as a failure to disclose by the inventors. It will be understood that the above description is for illustrative purposes only and not intended to impose any limitations. Those skilled in the art will find many embodiments and applications beyond those provided to be obvious upon reading the above description.

[0083] The explanations and examples presented herein are intended to familiarize those skilled in the art with the invention, its principles, and its practical applications. Those skilled in the art can adapt and apply the teachings to numerous forms that may be most appropriate to the specific requirements of their use. Accordingly, the specific embodiments of the teachings presented herein are not intended to be exhaustive or to limit the teachings. The scope of the teachings should therefore be determined not by reference to the foregoing description, but rather by reference to the accompanying claims and the full scope of the equivalents to which such claims are entitled. All disclosures of papers and references, including patent applications and patent publications, are incorporated by reference for all purposes. Furthermore, other combinations that can be gathered from the accompanying claims are implementable, and such combinations are also incorporated by reference into this written description. [Explanation of Symbols]

[0084] 10. Single polymer or polymer formulation 12 Foaming agent particles 14. Trapped gas bubbles

Claims

1. In the expandable filament composition, a single polymer or a blend of polymers selected from the group comprising ethylene octene copolymer, thermoplastic polyurethane, ethylene propylene diene monomer rubber, styrene-isoprene block copolymer, poly(styrene-butadiene-styrene), styrene-ethylene-butylene-styrene, nitrile rubber, styrene butadiene rubber, or a combination thereof; a foaming agent having an activation temperature of 110°C to 200°C; the single polymer or blend of polymers has a molecular weight sufficient to allow entanglement of the polymer chains; The composition, wherein the single polymer or blend of polymers is melt processable to form the resulting filament at a temperature sufficiently below the activation temperature of the foaming agent to avoid foam activation during filament formation.

2. 10. The composition of claim 1, wherein the single polymer or blend of polymers is melt processable at temperatures below 400°F (204.4°C).

3. 3. The composition of claim 1 or 2, wherein the single polymer or blend of polymers has a viscosity of 0.7 g / cm ３ ~0.99 g / cm ３ ethylene octene having an uncured density of

4. 4. The composition of claim 1, wherein the single polymer or blend of polymers each has a density of 0.7 g / cm ３ ~0.99 g / cm ３ 1. A composition comprising a blend of at least two ethylene octene polymers having an uncured density of

5. 5. The composition according to claim 1, wherein the single polymer or blend of polymers has a density of 0.5 g / cm ３ ~1.5g / cm ３ 1. A composition comprising a rubber or rubber blend having an uncured density of

6. 6. The composition of claim 1, wherein the resulting filaments have a density of 0.01 g / cm ３ ~1.5g / cm ３ The composition has a density after expansion of

7. 7. The composition of claim 1, wherein the resulting filaments have a density of 0.1 g / cm ３ ~0.5g / cm ３ The composition has a density after expansion of

8. 8. The composition of claim 1, wherein the resulting filaments have an Asker C foam hardness of 1 to 100.

9. 9. The composition of claim 1, wherein the resulting filaments have an Asker C foam hardness of 5 to 60.

10. 10. The composition of claim 1, wherein the resulting filaments have an Asker C foam hardness of 20 to 60.

11. 11. The composition of claim 1, wherein the resulting filaments have an Asker C foam hardness of 40 to 65.

12. 12. The composition of claim 1, wherein the resulting filaments have an average cell size after expansion of 0.1 mm to 2.0 mm.

13. 13. The composition of any one of claims 1 to 12, wherein the resulting filaments have an average foam cell size of 0.2 mm to 0.4 mm.

14. 14. The composition of claim 1, wherein the resulting filaments have an average cell size after expansion of 0.3 mm to 2.0 mm.

15. 15. A composition according to any one of claims 1 to 14, wherein the activation temperature of the foaming agent is between 135°C and 160°C.

16. 16. The composition of any one of claims 1 to 15, wherein the resulting filaments have a diameter in the range of 0.1 mm to 1.5 mm.

17. 17. The composition of any one of claims 1 to 16, wherein the resulting filaments have a diameter in the range of 0.8 mm to 1.2 mm.

18. 18. The composition of any one of claims 1 to 17, wherein the resulting filaments are at least partially or substantially open-celled material.

19. 19. The composition of any one of claims 1 to 18, wherein the composition comprises a particulate component.

20. 20. The composition of claim 1, wherein the composition includes a particulate component, the particulate component having a diameter that is between one-fifth (1 / 5) of the diameter of the unexpanded filaments and one-twentieth (1 / 20) of the diameter of the unexpanded filaments.

21. 21. The composition of claim 1, wherein the composition includes a particulate component, the particulate component having a diameter that is less than one-twentieth (1 / 20) of the diameter of the unfoamed filaments.

22. 22. The composition of any one of claims 1 to 21, wherein the single polymer or blend of polymers has a softening point below 120°C.

23. 23. The composition of any one of claims 1 to 22, wherein the foaming agent is a chemical foaming agent.

24. 24. The composition of any one of claims 1 to 23, wherein the single polymer or blend of polymers comprises a metallocene-catalyzed copolymer of ethylene and a higher molecular weight olefin monomer selected from propylene, butene, hexene, and octene.

25. 25. The composition of any one of claims 1 to 24, comprising a copolymer having a melt index of less than 5 g / 10 min.

26. 26. The composition of any one of claims 1 to 25, comprising a copolymer having a melt index greater than 20 g / 10 min.

27. 27. The composition of any one of claims 1 to 26, comprising one or more copolymers selected to provide an Asker C hardness of the foamed composition of less than 40.

28. 28. The composition of any one of claims 1 to 27, comprising one or more copolymers selected to provide an Asker C hardness of the foamed composition greater than 30.

29. 29. The composition of any one of claims 1 to 28, wherein the weight percent water absorption is from 0.2 to 1.

2.

30. 30. The composition of any one of claims 1 to 29, wherein the compression set of the composition is 10% to 15% change at 21°C as measured according to ASTM D3574-17 Test D.

31. 31. The composition of any one of claims 1 to 30, wherein the compression set of the composition is 28% to 32% change at 43°C as measured according to ASTM D3574-17 Test D.

32. 32. The composition of any one of claims 1 to 31, wherein the compression set of the composition is 30% to 38% change at 54°C as measured according to ASTM D3574-17 Test D.

33. 33. A composition according to any preceding claim, wherein the amount of foaming agent employed is from 0.5% to 4% by weight.

34. 34. The composition of any one of claims 1 to 33, wherein during extrusion the filaments have a die swell ratio percentage of less than 100%.

35. 35. A method of making the composition of claim 1, comprising melt-kneading the composition and extruding the composition to form the expandable filaments.

36. 36. A method comprising the steps of sewing a fabric with the expandable filament composition of claim 1 and expanding the filaments after sewing.

37. 37. Use of the expandable filament according to any one of claims 1 to 36 for weaving, knitting, inlaying, crocheting, braiding or 3D printing.

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