HK1117101B - Stretch composite film and composite fabric and processes for production of them - Google Patents

Description

Stretchable composite film and composite fabric, and method for producing same

Technical Field

The present invention relates to a composite film and a composite fabric each comprising a stretched and sintered porous film made of Polytetrafluoroethylene (PTFE) and having stretchability, preferably, water-proof moisture permeability, and a method for producing the same.

Background

As waterproof moisture-permeable films, sintered stretched porous polytetrafluoroethylene (ePTFE) films and laminated fabrics based on the sintered stretched porous PTFE films and fabrics have been proposed or put to practical use, but they do not have sufficient stretchability.

For example, Japanese patent laid-open No. Sho 51-30277 (see U.S. Pat. No. 3953566) discloses the following technique: a PTFE molded article obtained by extrusion molding a paste containing a PTFE powder is stretched and made porous at a temperature not higher than the crystal melting point of PTFE, and then sintered at a temperature not lower than the crystal melting point, for example, 350 to 370 ℃ for 5 seconds to 1 hour, whereby a stretched sintered porous PTFE film having improved strength such as tensile strength is obtained.

Further, Japanese patent application laid-open No. 55-7483 describes a material for forming an elastomer resin layer on a stretched sintered porous PTFE film. Although these Japanese patent laid-open Nos. Sho 51-30277 and Sho 55-7483 provide materials useful as clothing, they do not aim at providing materials having stretchability.

As a method for imparting stretchability, japanese patent laid-open publication No. 59-187845 discloses a method in which a composite film of a stretched porous polytetrafluoroethylene (ePTFE) film and an elastomer resin layer or a composite body obtained by laminating the composite film and a fabric is mechanically stretched under a condition that the yield point of ePTFE is at least 5% or more. The ePTFE film of japanese patent laid-open No. 59-187845 is considered to be a stretched sintered porous PTFE film obtained according to the description based on the technology of U.S. patent No. 3953566.

In the example of Japanese patent laid-open No. 59-187845, a composite of an ePTFE film 12 inches wide (14 inches long) and an elastomer resin is folded into a tape 1 to 1.25 inches wide, and the tape is stretched 2 times in the machine direction by an Instron tester (the nip gap of 9 inches is stretched 18 inches), so that the specimen is necked down to 3/8 to 1/2 inches in width. This method can realize 2-fold drawing by necking of the sample at the time of drawing. Here, the width necking down to about 1/2 at 2 times elongation indicates that essentially the size (total area) of the specimen does not change and the specimen deforms only in the direction of stretching. When the sample width is necked during stretching, wrinkles are generated in the stretching direction even if the tension during stretching is removed, and the sample width is restored to about 7 to 8 before stretching. Therefore, when a product is produced by this method, only a product having a width smaller than the width of the input fabric can be obtained, and the production cost increases. Further, since wrinkles are generated on the product, the appearance is deteriorated. Further, in the case where the stretching treatment is performed in the machine direction in a state where the necking in the width direction is prevented under the above conditions, since the ePTFE film obtained by sintering is used, the stretching of about 20% or so, that is, the breaking occurs, and the stretching treatment is difficult.

Although the final stretchability is not described in Japanese patent laid-open No. 59-187845, in example 1, the width is necked to about half at the stage of stretching to 2 times, which is an instantaneous stretch recovery of 64%. When the sample of practical example 1 was actually prepared and subjected to an elongation test by the method described later, the sample was necked to about half the width, and the elongation was 25% and the elongation recovery was 65%, which could not be said to have sufficient stretchability.

In addition, japanese patent laid-open No. 61-137739 discloses a moisture-permeable waterproof film having elasticity based on a composite film of an unsintered ePTFE film and an elastomer resin. That is, a method of impregnating and retaining an elastomer resin having a hydrophilic group in an unsintered ePTFE membrane to exhibit stretchability is disclosed. Among them, the ePTFE membrane is not sintered, which is an important condition for exhibiting stretchability. Since the ePTFE film is not sintered, a surface layer peeling phenomenon occurs due to insufficient cohesive force in the thickness direction. According to the description, if sintering is performed to avoid this, since there is no interfibrillary sliding, ductility is reduced, and even if sintered ePTFE is laminated with another laminated material, stretchability of the laminated material laminated with the sintered ePTFE is hindered by the sintered ePTFE, and stretchability as the whole laminated material is hardly obtained. That is, it means that the elastic resin is held in the sintered ePTFE film only by impregnation, and the stretchability is not exhibited.

In addition, Japanese patent application laid-open No. 61-137739 discloses a method of coating one or both surfaces with a resin having a hydrophilic group in order to avoid a peeling phenomenon of the surface layer. However, in the case of coating on one side, it was confirmed that the cohesion of the uncoated side was insufficient, and even in the case of coating on both sides, if pores of the ePTFE film remained inside, the cohesion was insufficient at that portion. In order to completely prevent the peeling phenomenon of the surface layer, it is necessary to completely impregnate the inside of the ePTFE membrane with a resin having a hydrophilic group, and the thickness of the resin layer inevitably increases. Since the resin having a hydrophilic group has hydrophilicity, moisture permeability is exhibited by dissolving moisture in the resin, but as long as moisture moves by diffusion in the nonporous resin layer, the thicker the thickness of the nonporous resin, the lower the moisture permeability. The unsintered ePTFE film has insufficient durability in practical use if it is not completely impregnated with a resin having a hydrophilic group in order to prevent peeling of the surface layer or the like, and it is difficult to exhibit high moisture permeability if it is completely impregnated.

Disclosure of The Invention

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a composite film and a composite fabric having stretchability, each of which contains a sintered stretched porous polytetrafluoroethylene (ePTFE) film, and a method for producing the composite film and the composite fabric. It is a preferable object to provide a composite membrane and a composite fabric each comprising a sintered expanded porous polytetrafluoroethylene (ePTFE) membrane and having water-proof and moisture-permeable properties, and a method for producing the same. Further, the present invention aims to provide a textile product comprising the stretchable composite fabric.

One aspect of the present invention relates to a stretchable composite film comprising a stretched sintered porous film substantially made of polytetrafluoroethylene and an elastomer resin layer formed on at least one surface of the stretched sintered porous film, wherein the tensile stress of the composite film at 10% elongation in the machine direction and/or transverse direction is 2.5N/15mm or less, and/or the composite film has 30% or more elongation in the machine direction and/or transverse direction and 70% or more elongation recovery rate. Further, the elastomer resin layer preferably contains a polyurethane resin.

Another aspect of the present invention relates to a stretchable composite fabric obtained by laminating a stretchable fabric on one surface or both surfaces of a composite film comprising a stretched sintered porous film substantially made of polytetrafluoroethylene and an elastomer resin layer formed on at least one surface of the stretched sintered porous film, wherein the composite fabric has a tensile stress of 2.5N/15mm or less at 10% elongation in the longitudinal direction and/or the transverse direction, and/or has an elongation of 30% or more in the longitudinal direction and/or the transverse direction and a recovery rate of elongation of 70% or more. Further, the elastomer resin layer preferably contains a polyurethane resin.

Another aspect of the present invention relates to a textile product comprising a stretchable composite fabric in which a stretchable fabric is laminated on one surface or both surfaces of a composite film comprising a stretch-sintered porous film substantially made of polytetrafluoroethylene and an elastomer resin layer formed on at least one surface of the stretch-sintered porous film, wherein the composite fabric has a tensile stress of 2.5N/15mm or less when elongated by 10% in the longitudinal direction and/or the transverse direction, and/or has an elongation of 30% or more in the longitudinal direction and/or the transverse direction and an elongation recovery rate of 70% or more.

One aspect of the present invention relates to a method for continuously producing a stretchable composite film including a stretched sintered porous film substantially made of polytetrafluoroethylene and an elastomer resin layer formed on at least one surface of the stretched sintered porous film, the method including the steps of:

(1) continuously forming the elastomer resin layer on at least one surface of the stretched and sintered porous film;

(2) continuously stretching the multilayer film obtained in the above (1) in a biaxial direction or in a uniaxial direction without causing shrinkage in a direction perpendicular to the stretching direction at a stretching ratio of 1.3 times or more which is less than the yield point of the stretched sintered porous film; and

(3) and (3) relaxing the stretched multilayer film obtained in the above (2).

In the method for producing the stretchable composite film, the stretching step is preferably performed under a heating condition of 100 to 200 ℃, and the stretching step is preferably performed at a stretching speed of 5%/second or more. The relaxation step is preferably performed at 100 ℃ or lower.

One aspect of the present invention relates to a method for continuously producing a stretchable composite fabric in which a stretchable fabric is laminated on one or both surfaces of a composite film including a stretched sintered porous film substantially made of polytetrafluoroethylene and an elastomer resin layer formed on at least one surface of the stretched sintered porous film, the method comprising:

(1) continuously forming the elastomer resin layer on at least one surface of the stretched and sintered porous film;

(2) a step of continuously laminating a stretchable fabric on one or both surfaces of the multilayer film obtained in the above (1), and a step of continuously stretching the laminated fabric obtained in the laminating step in a biaxial direction at a stretch ratio of 1.3 times or more less than the yield point of the stretched sintered porous film or in a uniaxial direction without shrinking in a direction perpendicular to the stretching direction, or

(2') continuously stretching the multilayer film obtained in the above (1) in a biaxial direction or a uniaxial direction without causing shrinkage in a direction perpendicular to the stretching direction at a stretching magnification of 1.3 times or more less than the yield point of the stretched sintered porous film, and continuously laminating a stretchable fabric on one or both surfaces of the stretched multilayer film obtained in the stretching step; and

(3) and (3) relaxing the stretched laminated fabric obtained in the above (2) or (2').

In the method for producing a stretchable composite fabric, the stretching step is preferably performed under a heating condition of 100 to 200 ℃, and the stretching step is preferably performed at a stretching speed of 5%/second or more. The relaxation step is preferably performed at 100 ℃ or lower.

One aspect of the present invention relates to a stretchable composite film comprising a stretch-sintered porous film and an elastomer resin layer, the method for producing the porous film comprises continuously forming the elastomer resin layer on at least one surface of a stretched sintered porous film substantially made of polytetrafluoroethylene, continuously stretching the obtained multilayer film in a biaxial direction at a stretch ratio of 1.3 times or more less than the yield point of the stretched sintered porous film or in a uniaxial direction without shrinking in a direction perpendicular to the stretching direction, and then relaxing the obtained stretched multilayer film, characterized in that the tensile stress of the composite film at 10% elongation in the longitudinal and/or transverse direction is 2.5N/15mm or less, and/or the composite film has an elongation in the longitudinal and/or transverse direction of 30% or more and a recovery from elongation of 70% or more.

Another aspect of the present invention relates to a stretchable composite fabric comprising a stretch-sintered porous film, an elastomer resin layer and a stretchable fabric, and a method for producing the stretchable composite fabric, which comprises

(1) A step of continuously forming the elastomer resin layer on at least one surface of a stretched sintered porous film substantially made of polytetrafluoroethylene,

(2) a step of continuously laminating a stretchable fabric on one or both surfaces of the multilayer film obtained in the above (1), and a step of continuously stretching the laminated fabric obtained in the laminating step in a biaxial direction at a stretch ratio of 1.3 times or more less than the yield point of the stretched sintered porous film or in a uniaxial direction without shrinking in a direction perpendicular to the stretching direction, or

(2') a step of continuously stretching the multilayer film obtained in the above-mentioned (1) in a biaxial direction or a uniaxial direction without causing shrinkage in a direction perpendicular to the stretching direction at a stretching ratio of 1.3 times or more less than the yield point of the stretched sintered porous film, a step of continuously laminating a stretchable fabric on one or both surfaces of the stretched multilayer film obtained in the stretching step, and

(3) a step of relaxing the stretched laminated fabric obtained in the above (2) or (2'); characterized in that the tensile stress at 10% elongation in the longitudinal and/or transverse direction of the composite fabric is 2.5N/15mm or less, and/or the elongation in the longitudinal and/or transverse direction of the composite fabric is 30% or more and the elongation recovery rate is 70% or more.

If the present invention is used, a composite film, a composite fabric and a textile product having good elongation and elongation recovery properties can be provided, and if a preferred form is used, they also have waterproof moisture permeability. In the preferred embodiment, since a sintered expanded porous polytetrafluoroethylene (ePTFE) film is used as the substrate, the elastomer resin layer can have practical durability even if it is not completely impregnated in the ePTFE film, and a composite film, a composite fabric, and a textile product having high moisture permeability can be provided. Further, according to the present invention, there can be provided a method for manufacturing the composite film and the composite fabric. By adopting the preferred mode, a method for producing a composite film or a composite fabric having excellent elongation and elongation recovery properties can be provided by treating the fabric at a temperature and a rate of the stretching treatment within a specific range.

Brief description of the drawings

Fig. 1 is an explanatory view showing an infrared absorption spectrum of an ePTFE membrane.

FIG. 2 is an explanatory view of an electron micrograph of a sintered ePTFE membrane surface before stretching treatment.

Fig. 3 is an explanatory view showing the influence of the stretching speed in the stretching treatment of the composite film of the present invention.

Best Mode for Carrying Out The Invention

The stretchable composite film of the present invention is a composite film comprising a stretched sintered porous film substantially made of polytetrafluoroethylene and an elastomer resin layer formed on at least one surface of the stretched sintered porous film, wherein the tensile stress at 10% elongation in the longitudinal and/or transverse direction of the composite film is 2.5N/15mm or less, and/or the elongation in the longitudinal and/or transverse direction of the composite film is 30% or more and the elongation recovery rate is 70% or more.

The sintered porous (sintered ePTFE) membrane substantially made of polytetrafluoroethylene of the present invention is obtained by stretching a Polytetrafluoroethylene (PTFE) membrane and heat-treating the stretched PTFE membrane at a temperature not lower than the melting point, for example, 350 to 370 ℃ for 5 seconds to 1 hour, and has the characteristics of high porosity for obtaining high moisture permeability, no peeling of the surface layer, good durability, softness, extremely high hydrophobicity, good chemical resistance, good heat resistance, and the like.

The PTFE of the present invention includes modified PTFE obtained by copolymerizing tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), or the like, PTFE in which inorganic or organic substances are mixed in an amount of up to about 20 wt%, and the like.

Sintered ePTFE membranes such as "crystalline to polytetrafluoroethylene" include Raman spectra, infrared spectra and¹⁹comparative quantitative Study of nuclear magnetic resonance spectrum of F (synthetic quantitative Study on the crystalline of poly (fluoroethylene) including Raman, infra-red and¹⁹f nuclear magnetic resonance spectroscopy), R.J.Lehnert, Polymer (Ploymer), Vol.38, No. 7, page 1521-1535 (1997), at 780cm infrared absorption measured with an infrared spectrophotometer^-1Amorphous absorption of PTFE by sintering occurs.

For example, an infrared spectrophotometer "paramon 1000" manufactured by Perkinelmer was used, and the medium was KRS-5 (incident angle: 45 degrees, resolution: 4 cm)^-1Scanning 20 times) was conducted to measure infrared absorption at 780cm^-1Absorption was confirmed. As shown by the spectrum in FIG. 1, the unsintered ePTFE membrane was found to be 780cm^-1No absorption was seen at all. But the sintered ePTFE membrane confirmed absorption. When an elastomer resin layer is formed on one surface of an ePTFE film, the ePTFE film surface is measured, and when an elastomer resin layer is formed on both surfaces of the ePTFE film, the ePTFE film surface is exposed by peeling off an adhesive tape or the like attached to the elastomer resin layer, and the exposed ePTFE film surface is measured.

Further, sintering was confirmed using a Differential Scanning Calorimeter (DSC). For example, in the commemorative lecture of Toronto published by clean water in 7.1988 for 50 years, the difference in melting temperature according to the degree of sintering as measured by DSC is explained. Wherein, in the case where the unsintered ePTFE has a melting peak at 345 to 347 ℃, the semi-sintered ePTFE has a melting peak at 330 to 340 ℃, the fully sintered ePTFE has a melting peak at 327 ℃, and only the PTFE portion is obtained as a sample, the determination by DSC can be performed. In addition, the sintered ePTFE formed of polytetrafluoroethylene of the present invention also includes ePTFE in a semi-sintered state. The ePTFE in a semi-sintered state can be obtained by heat treatment at a temperature of the melting point (327 ℃) of PTFE or higher for 5 seconds to 1 hour. That is, the heat treatment above the melting point of PTFE means sintering.

The maximum pore size of the sintered ePTFE membrane is 0.01 to 10 μm, preferably 0.1 to 1 μm. If the maximum pore diameter of the sintered ePTFE membrane is less than 0.01 μm, it is difficult to produce the membrane, and if it exceeds 10 μm, not only the water resistance of the membrane is lowered, but also the membrane strength is weakened, so that handling in a subsequent step such as lamination becomes difficult, which is undesirable. The maximum pore diameter was determined in accordance with the ASTM F-316.

In addition, the porosity of the sintered ePTFE membrane is 50 to 98%, preferably 60 to 95%. If the porosity of the sintered ePTFE membrane is less than 50%, the moisture permeability becomes low, whereas if it exceeds 98%, the strength of the membrane decreases. The porosity was determined by calculating the apparent density (ρ) from the apparent density measurement according to JIS K6885 by the following formula (1).

Porosity (%) - (2.2. rho)/2.2X 100 (1)

The thickness of the sintered ePTFE membrane is 7 to 300 μm, preferably 10 to 100 μm. If the thickness of the sintered ePTFE film is less than 7 μm, a problem arises in handling property at the time of production, and if it exceeds 300 μm, not only flexibility of the film is impaired, but also moisture permeability is lowered. The thickness of the film was measured using an average thickness measured by a direct-reading thickness meter (measured using an 1/1000mm direct-reading thickness meter manufactured by dele corporation under a condition where no load other than the own spring load was applied).

The sintered ePTFE membrane of the present invention may comprise a membrane having a water and/or oil repellent polymer coated on the inner surface of its pores as desired. In this case, an example of the polymer may be a polymer having a fluorine-containing branch chain. Specific details of such a polymer and a method for compounding the polymer into a sintered ePTFE membrane are disclosed in WO94/22928 and the like.

As the coating polymer, those represented by the following general formula (I)

(wherein n is an integer of 3 to 13, and R is hydrogen or methyl)

The fluorine-containing polymer is a polymer obtained by polymerizing a fluoroalkyl acrylate and/or a fluoroalkyl methacrylate (the fluoroalkyl moiety preferably has 6 to 16 carbon atoms). When the pores of the sintered ePTFE membrane are coated with the polymer, an aqueous microemulsion (average particle diameter of 0.01 to 0.5 μm) of the polymer is formed using a fluorine-containing surfactant (for example, ammonium perfluorooctanoate), and the polymer is impregnated into the pores of the sintered ePTFE membrane, followed by heating. This can provide a sintered ePTFE membrane in which not only water and the fluorosurfactant are removed, but also the fluoropolymer is melted to coat the inner surface of the pores of the sintered ePTFE membrane, and good water and oil repellency of the continuous pores is maintained. Further, as other polymers, "AF polymer" (trade name of DuPont corporation), "CYTOP" (trade name of Asahi glass Co., Ltd.) and the like can be used. When the inner surface of the pores of the sintered ePTFE film is coated with these polymers, these polymers are dissolved in an inert solvent such as "フロリナ - ト" (trade name of sumitomo 3M corporation), and the resulting solution is impregnated into the sintered ePTFE film, followed by evaporation to remove the solvent. When the sintered ePTFE membrane is contaminated with various contaminants by coating the inner surface of the pores of the sintered ePTFE membrane with the organic polymer, the contaminants are less likely to permeate into the sintered ePTFE membrane, and deterioration in hydrophobicity of the sintered ePTFE membrane can be prevented.

The elastic composite membrane of the present invention is obtained by forming an elastomer resin in a membrane-like form on at least one surface of the sintered ePTFE membrane. The elastomer resin may be appropriately used as long as it is a resin having elasticity, such as a silicone resin, a fluorine-containing rubber, a synthetic rubber such as NBR, epichlorohydrin, EPDM, or the like, a natural rubber, a polyester resin, or a urethane resin, and when it is used for an application requiring heat resistance, a silicone resin, a fluorine-containing rubber, or the like is preferable. In addition, from the viewpoint of moisture permeability, it is preferable to use a water-swellable and water-insoluble moisture-permeable resin as a polymer material having a hydrophilic group such as a hydroxyl group, a carboxyl group, a sulfonic group, or an amino acid group. Specifically, hydrophilic polymers such as polyvinyl alcohol, cellulose acetate, and nitrocellulose, which are at least partially crosslinked, and hydrophilic urethane resins can be exemplified, and hydrophilic urethane resins are particularly preferable if chemical resistance, processability, moisture permeability, and the like are taken into consideration. The resin may be used by mixing two or more kinds of resins as appropriate, or may be used by mixing an inorganic or organic filler for the purpose of improving durability, imparting electrical resistance, or the like.

As the hydrophilic urethane resin, polyester-based or polyether-based polyurethane or prepolymer containing a hydrophilic group such as a hydroxyl group, an amino group, a carboxyl group, a sulfonic acid group, or an oxyethylene group can be used, and in order to adjust the melting point (softening point) as a resin, diisocyanate or triisocyanate having 2 or more isocyanate groups, or adducts thereof can be used singly or in combination as a crosslinking agent. In addition, 2-or more functional diols, triols, diamines, triamines may be used as the curing agent for the isocyanate-terminated prepolymer. In order to maintain high moisture permeability, 2-functional is better than 3-functional.

In the stretchable composite film of the present invention, the thickness of the elastomer resin layer is preferably 5 to 500 μm, more preferably 10 to 300 μm. When the thickness of the elastomer resin layer is 5 μm or less, the elongation recovery of the stretchable composite film is insufficient, and when it is 300 μm or more, the stretchable composite film becomes hard and heavy. When the stretchable composite film is used for applications requiring moisture permeability, the thickness of the elastomer resin layer is preferably 5 to 100 μm, more preferably 10 to 70 μm. When the thickness of the elastomer resin layer is 5 μm or less, the elongation recovery of the stretchable composite film is insufficient, and when it is 100 μm or more, the moisture permeability is insufficient.

Further, when the elastomer resin layer formed on at least one surface of the sintered ePTFE membrane partially penetrates into the sintered ePTFE membrane, the elastomer resin layer can be prevented from peeling off, and the durability can be improved, which is preferable. When a moisture-permeable resin is used as the elastomer resin, the thickness of the portion of the moisture-permeable resin that penetrates into the sintered ePTFE film is preferably 3 to 30 μm, more preferably 5 to 20 μm, from the viewpoints of moisture permeability, flexibility (hand feeling), and durability. If the thickness is less than 3 μm, the durability is practically insufficient, and if it exceeds 30 μm, the moisture permeability is too low. The thickness of the polyurethane resin layer is obtained by visually measuring the average thickness on the basis of a cross-sectional photograph (1000 to 3000 times) of an electron microscope using a scale (scale indicating the length) of the electron microscope photograph.

When the stretch composite film of the present invention is used for applications requiring moisture permeability such as textile products, the moisture permeability of the stretch composite film is preferably 2000～100000g/m²24 hours, more preferably 3000 to 70000g/m²24 hours. The moisture permeability is a value obtained by converting a measurement value obtained by JIS L1099B-2 method into a value for 24 hours.

In the stretchable composite film of the present invention, the elastic resin layer may be formed in a film form on both surfaces of the sintered ePTFE film. In this case, the above-described elastomer resin may be used, and the same elastomer resin may be used for both surfaces, or different elastomer resins may be used for each surface depending on the application.

The stretchable composite film is characterized in that the tensile stress of the composite film at 10% elongation in the machine direction and/or transverse direction is 2.5N/15mm or less, and/or the elongation in the machine direction and/or transverse direction of the composite film is 30% or more and the elongation recovery rate is 70% or more. That is, at least one of a tensile stress at 10% elongation of 2.5N/15mm or less and an elongation of 30% or more and an elongation recovery of 70% or more is satisfied.

In order to obtain practical stretchability, a composite film satisfying all of the ranges of tensile stress, elongation, and elongation recovery is most desirable. In some cases, the elongation and the elongation recovery rate are within predetermined ranges, and the tensile stress at 10% elongation is outside the above-mentioned range. The tensile stress at which 10% elongation is possible is in the above range, and the elongation recovery rate are out of the predetermined ranges. With respect to these properties, at least one of the longitudinal direction and the transverse direction of the composite film may satisfy a predetermined property.

The elongation and the elongation recovery rate are more preferably a composite film having an elongation of 35% or more and an elongation recovery rate of 80% or more, particularly preferably a composite film having an elongation of 40% or more and an elongation recovery rate of 90% or more, and such a composite film exhibits more excellent stretchability. Elongation the elongation after 1 minute was measured with a load of 300g according to JIS L1096B. The elongation recovery was measured in accordance with JIS L1096B-1 with the weight removal time being 1 minute.

The tensile stress at 10% elongation of the stretchable composite film of the present invention is more preferably a composite film of 2N/15mm or less, particularly preferably a composite film of 1.5N/15mm or less, in terms of exhibiting good (easy-to-stretch) stretchability. The tensile stress was measured by subjecting a specimen having a width of 15mm to a tensile test at a tensile rate of 200 mm/min.

Small stress during stretching (small resistance during stretching, and stretching with a small force) is also an important factor for the body to feel stretchability. For example, a composite film having an elongation of 20% and a tensile stress of 3.25N/15mm at 10% elongation is poor in stretchability, while a composite film having the same elongation and a tensile stress of 1.85N/15mm at 10% elongation is easy to stretch and can feel stretchability to the body.

A method for continuously producing the aforementioned stretch composite film according to the present invention is a method for producing a stretch composite film, comprising the steps of: (1) continuously forming an elastomer resin layer on at least one surface of a stretched sintered porous (sintered ePTFE) film substantially made of polytetrafluoroethylene; (2) continuously stretching the multilayer film obtained in the above (1) in a biaxial direction or in a uniaxial direction without causing shrinkage in a direction perpendicular to the stretching direction at a stretching ratio of 1.3 times or more less than the yield point of the sintered ePTFE film; and (3) a step of relaxing the stretched multilayer film obtained in the above (2).

In the method for producing the stretchable composite membrane, as a method for continuously forming a layer of an elastomer resin, preferably the above-mentioned hydrophilic polyurethane resin, on one surface of the porous structure of the sintered ePTFE membrane, a method for impregnating and adhering the porous structure with the elastomer resin can be used. The method for impregnating and adhering the hydrophilic polyurethane resin is not particularly limited, and the polyurethane resin is solubilized with a solvent or melted by heating to prepare a coating solution, and the coating solution is applied to the sintered ePTFE membrane by, for example, a roll coater or the like. The viscosity of the coating liquid suitable for dipping and adhesion is 20000cps or less, preferably 10000cps or less at the coating temperature. When the solution is made by using a solvent, it is preferable to maintain a viscosity of 500cps or more, because if the viscosity is too low, the solution diffuses into the whole sintered ePTFE membrane after coating, and the whole is hydrophilic, which causes a problem in water repellency, or the hydrophilic urethane resin is impregnated in a large amount, which makes the resin layer thick and makes it impossible to obtain high moisture permeability. For the measurement of the viscosity, for example, a B-type viscometer manufactured by eastern industries co. Since the porous structure of the sintered ePTFE membrane and the impregnation property of the hydrophilic polyurethane resin impregnated and attached vary depending on the surface tension, pore diameter, temperature, pressure, and the like, it is necessary that the hydrophilic polyurethane resin is impregnated but does not diffuse throughout the sintered ePTFE membrane, and that the hydrophilic polyurethane resin forms a thin film on the surface of the sintered ePTFE membrane. The viscosity condition of the aforementioned coating liquid containing a hydrophilic urethane resin is effective for a sintered ePTFE membrane having a maximum pore diameter of about 0.2 μm.

The method for producing a stretchable composite film of the present invention is characterized by performing a stretching treatment while preventing necking. That is, the sintered ePTFE membrane is characterized in that the membrane is stretched in the stretching direction while the membrane dimension perpendicular to the stretching direction is fixed to a constant value or elongated at the yield point or less of the sintered ePTFE membrane.

For reference, fig. 2 shows an example of an electron micrograph obtained by taking 2000 times the sintered ePTFE surface before the stretching treatment. In fig. 2, the nodes and fibrils extending from the nodes are confirmed. For example, if the sintered ePTFE membrane is elongated in the transverse direction without fixing the longitudinal dimension thereof, the pore shape becomes elongated in the transverse direction, and elongation in the transverse direction and necking in the longitudinal direction occur. In contrast, the present invention means that the total area of the sample is increased by the stretching treatment so that the fibrils of the sintered ePTFE are newly pulled out from the nodes or the original fibrils are further extended. PTFE has a high plastic deformability and no elasticity, but it is almost restored to its original shape (size) in the relaxation step by the elasticity of the elastomer resin layer impregnated and adhered. By allowing the sintered ePTFE to expand and then to return to its original size in the relaxation step (continuous processing for preventing necking), it is possible to achieve, for the first time, stretchability having an elongation of 30% or more and an elongation return of 70% or more in combination with the elasticity of the elastomer resin layer, and the tensile stress at 10% elongation is 2.5N/15mm or less. As described above, the production process of the present invention and the stretchable composite film obtained by the production process are fundamentally different from the invention based on the method described in the aforementioned Japanese patent application laid-open No. Sho 59-187845 in terms of fibril growth and new extraction.

The dimensional recovery of the stretched multilayer film before and after the stretching step and the relaxing step in the production method of the present invention is 80% or more, preferably 85% or more. If the dimensional recovery of the stretched multilayer film is less than 80%, the stretchability of the resulting stretchable composite film becomes insufficient. The dimensional recovery was calculated from the size of the multilayer film before the stretching treatment (L1), the stretching size during the stretching treatment (L2), and the size of the stretch composite film after relaxing the stretched multilayer film (L3) by the following formula (2).

Size recovery (%) - (L2-L3)/(L2-L1) × 100 (2)

In order for the body to feel the desired stretchability, it is necessary that the elongation and recovery from elongation be high and the tensile stress at 10% elongation be low. This makes it possible to provide the body with extensibility (extensibility) and recovery (contractibility) under low stress. In order to elongate the sintered ePTFE membrane, stretching may be performed to a desired ratio by stretching in a state of heating to some extent. In view of the balance between elongation and recovery, the stretching treatment temperature is preferably 100 to 200 ℃ and particularly preferably 120 to 180 ℃.

When the stretching treatment is carried out at a temperature exceeding 200 ℃, the elastomer resin is heat-set in an elongated state, and after the stretching is completed, the dimensional recovery is poor, and the product cannot be said to have stretchability. Further, if the stretching treatment is carried out at a temperature lower than 100 ℃, the ePTFE film is sintered, so that the slippage between fibrils and the extraction of new fibrils from the nodes are poor, and as a result, the ePTFE film cannot be stretched to a desired elongation.

In the composite film of the sintered ePTFE film having a transverse elongation at break of 200% and the elastomer resin of the present invention, if the composite film is stretched at 150 ℃ under conditions of an elongation of 1.4 times and a stretching speed of 50%/second, for example, and the tension is released after stretching to recover (relax), a film having good stretchability with an elongation of 30%, an elongation recovery of 90%, and a tensile stress of 1.85N/15mm at 10% elongation can be obtained. Even if the same film is stretched at a temperature of 90 ℃ under the conditions of an elongation of 1.4 times and a stretching speed of 50%/second, the film is broken during the stretching process and cannot be stretched. Further, the same film was stretched at 210 ℃ under conditions of an elongation factor of 1.4 times and a stretching speed of 50%/second, and after stretching, the tension was released to recover the film, and the obtained film was a film having poor stretchability, an elongation percentage of 15%, a recovery percentage of elongation of 38%, and a tensile stress at 10% elongation of 2.8N/15 mm.

The recovery rate of the film size after the relaxation step was also found to be different depending on the stretching speed. When the stretching speed is too low, it takes a long time to stretch the film to a predetermined magnification, resulting in a long heat-setting time of the film, and the stretchability is deteriorated as in the case of the stretching treatment at a high temperature. The stretching speed is preferably 5%/second or more, particularly preferably 10%/second or more.

The sintered ePTFE membrane can adjust the easy extensibility in the cross direction by the balance of the elongation in the cross direction. The composite membrane of the sintered ePTFE membrane and the elastomer resin is also balanced in the easy extensibility of the sintered ePTFE membrane serving as the substrate. A sintered ePTFE membrane that is easily extensible in the transverse direction can be obtained, for example, by reducing the elongation in the transverse direction relative to the elongation in the longitudinal direction. The present invention is not limited to the direction of easy stretching, but generally, a wide variety of transversely stretching cloths are available at low cost, and a sintered ePTFE membrane which is transversely easy to stretch is preferably used.

In the method for producing a stretchable composite film of the present invention, the stretching step is preferably performed under a heating condition of 100 to 200 ℃ and at a stretching speed of 5%/second or more. When the elongation is set in the machine direction and the sheet is stretched only in the transverse direction, the elongation in the transverse direction is preferably 1.3 times or more, particularly preferably 1.4 times or more. Further, in the case where the transverse direction is fixed so as to be elongated only in the longitudinal direction, the elongation in the longitudinal direction is preferably 1.3 times or more, particularly preferably 1.4 times or more. When the film is stretched in the biaxial direction, the longitudinal elongation is preferably at least 1.3 times, particularly preferably at least 1.4 times, and the transverse elongation is preferably at least 1.3 times, particularly preferably at least 1.4 times. When the elongation is less than the above range, the stretchability of the resulting stretchable composite film may become insufficient. The higher the elongation is, the better it is within the range that the sintered ePTFE film does not break, but generally the upper limit is about 2 times in the case of uniaxial elongation and about 1.7 times in the case of biaxial elongation.

In the method for producing a stretchable composite film of the present invention, the relaxation step is preferably performed at 100 ℃ or lower, particularly preferably at room temperature to 80 ℃. If the relaxation step is carried out at a temperature exceeding 100 ℃, the dimensional recovery after the relaxation step is less than 80%, and hence the stretchability becomes insufficient. The method of relaxing is not particularly limited, and for example, the tension applied to the stretchable composite film may be released to cause the stretchable composite film to shrink naturally.

The stretchable composite fabric of the present invention is a composite fabric obtained by laminating a stretchable fabric on one side or both sides of the stretchable composite film, wherein the composite fabric has a tensile stress of 2.5N/15mm or less when elongated by 10% in the longitudinal direction and/or the transverse direction, and/or has an elongation of 30% or more in the longitudinal direction and/or the transverse direction and an elongation recovery rate of 70% or more. The tensile stress, elongation and elongation recovery rate referred to here are basically the same as in the case of the aforementioned stretch composite film.

The stretch fabric may be any material as long as it can function as a protective layer of the stretch composite film and has stretch properties, and is preferably a woven fabric, a knitted fabric, a nonwoven fabric, a net or the like made of synthetic fibers or natural fibers. As the synthetic fibers, those of polyamides, polyesters, polyurethanes, polyolefins, polyvinyl chloride, polyvinylidene chloride, polyfluorocarbons, polyacrylics, etc. are preferably used. Further, since the stretch property is good, it is preferable to use a fabric made of a polyurethane elastic fiber having stretch property or a special Polyester (PBT) fiber, a fabric partially using these fibers in combination, a fabric called mechanical stretch (mechanical stretch) obtained by applying a special "twisted yarn" to a yarn, or the like. Further, since the knitted fabric or the like has elasticity in its structure, it can be preferably used. As the natural fiber, fibers of cotton, hemp, animal hair, silk, and the like can be used.

When the stretchable composite film and the stretchable fabric are laminated, a method of laminating a fabric on one side of the stretchable composite film to form a 2-layer structure or a method of laminating a fabric on both sides of the stretchable composite film to form a 3-layer structure can be employed.

The method for producing a stretchable composite fabric of the present invention is characterized by comprising the steps of:

(1) continuously forming an elastomer resin layer on at least one surface of a stretched sintered porous (sintered ePTFE) film substantially made of polytetrafluoroethylene; (2) a step of continuously laminating a stretchable fabric on one surface or both surfaces of the multilayer film obtained in the above-mentioned (1), and a step of continuously stretching the laminated fabric obtained in the above-mentioned lamination step in a biaxial direction at a stretch ratio of 1.3 times or more, which is less than the yield point of the stretch-sintered porous film, or in a uniaxial direction without shrinking in a direction perpendicular to the stretch direction, or (2') a step of continuously stretching the multilayer film obtained in the above-mentioned (1) in a biaxial direction at a stretch ratio of 1.3 times or more, which is less than the yield point of the stretch-sintered porous film, or in a uniaxial direction without shrinking in a direction perpendicular to the stretch direction, and a step of continuously laminating a stretchable fabric on one surface or both surfaces of the multilayer film obtained in the above-mentioned stretching step; and (3) a step of relaxing the stretched laminated fabric obtained in the above (2) or (2'). Here, the method of forming the elastomer resin layer on the surface of the sintered ePTFE film is basically the same as the method of producing the stretchable composite film described above. The process of stretching the laminated fabric and the process of relaxing the stretched laminated fabric are basically the same as the above-described methods.

The stretch fabric may be laminated on a multilayer film having an elastomer resin layer formed on the surface of a sintered ePTFE film and then subjected to a stretching treatment, or the stretch fabric may be laminated after the stretching treatment of the multilayer film.

The stretchable composite film and the stretchable fabric can be laminated by a known method. For example, the following methods can be used: a method in which an adhesive is applied to a stretchable composite film by a gravure-patterned roll, a stretchable fabric is bonded to the adhesive, and the adhesive is pressure-bonded to the stretchable composite film by the roll; a method of spraying an adhesive onto an elastic composite film, attaching an elastic fabric thereto, and pressure-bonding the elastic fabric with a roller; and a method of heat-sealing the stretchable composite film and the stretchable fabric in a state of being stacked on each other by a heat roll.

The laminate of the stretch fabric and the stretch composite film is preferably obtained by adhesion. As the adhesive used for lamination, any adhesive may be used as long as it is unlikely to cause a decrease in adhesive strength under normal use conditions, and various adhesives known in the art may be used. Generally, a water-insoluble adhesive is used. Such a water-insoluble adhesive includes a curable resin that is cured by heat, light, or the like, in addition to a thermoplastic resin. Specific examples of the water-insoluble adhesive include various resins such as polyesters, polyamides, polyurethanes, silicones, polyacrylics, polyvinyl chlorides, polybutadienes, rubbers, and polyolefins. As the polyurethane adhesive, a curing reaction type hot melt adhesive can be particularly preferably used. The curing reaction type hot melt adhesive in this case is an adhesive which is solid at ordinary temperature, forms a low viscosity liquid by melting under heating, and forms a high viscosity liquid or a cured product by applying and holding the adhesive in a liquid state or raising the temperature to cause a curing reaction. In this case, the viscosity of the melt after melting by heating, i.e., before coating the back cloth, is 500 to 30000cps, preferably 500 to 3000 cps; on the other hand, the viscosity of the melt after the melt has been made high-viscosity, that is, after the film and the back cloth are laminated with the melt, is 500 to 20000cps, preferably 10000cps or more. The solidification reaction of the melt is carried out in the presence of a solidification catalyst, a solidification agent, and water.

A preferable example of the curing reaction type adhesive is a urethane prepolymer which undergoes a curing reaction by moisture (moisture). The polyurethane prepolymer can be obtained by addition reaction of (I) a polyol component such as a polyester polyol or a polyether polyol and (II) a polyisocyanate component such as an aliphatic or aromatic diisocyanate or triisocyanate, such as Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylylene diisocyanate, or isophorone diisocyanate. In this case, the polyurethane prepolymer has an isocyanate group at its terminal, and undergoes a curing reaction in the presence of moisture. The melting temperature of the polyurethane prepolymer is above 50 ℃ slightly higher than room temperature, preferably 80-150 ℃. Such a polyurethane prepolymer is available, for example, from NSC corporation of Japan as trade name "ボンドマスタ one". The polymer is heated to 70 to 150 ℃ to form a molten liquid having a viscosity capable of being applied to a substrate, the stretchable fabric and the stretchable composite film are bonded to each other using the molten liquid, and then the bonded fabric is cooled to about room temperature to form a semisolid state, excessive permeation and diffusion of an adhesive to the fabric is prevented, and soft and firm bonding can be obtained by moisture curing in the air.

The area of the adhesive or fusion bonding in the above lamination is 3 to 90%, preferably 5 to 80%. If the area is less than 3%, the strength of adhesion or fusion bonding between the stretchable composite film and the stretchable fabric cannot be sufficiently obtained, and if it exceeds 90%, the hand of the resulting stretchable composite fabric becomes hard and the moisture permeability becomes insufficient.

The fiber product of the present invention is characterized by containing the aforementioned stretchable composite fabric. The textile product is a product whose constituent elements include a fabric, and examples thereof include wearing products such as clothes, hats, gloves, and shoes, bedding products such as bedding, sheets, and sleeping bags, film structures such as tents, and bags such as bags. For example, in the case of a rain gear having waterproof and moisture-permeable properties using the stretchable composite fabric having a 2-layer structure of the present invention, the stretchable fabric is used with its surface on the outside and the elastomer resin layer on the body side.

When the sintered ePTFE membrane is used on the body side, water vapor generated from the body permeates the pores of the sintered ePTFE membrane, adheres to the surface of the elastomer resin impregnated into the pores, permeates and diffuses into the elastomer resin layer, and evaporates from the surface of the elastomer resin layer, and therefore the substantial effective membrane area of the elastomer resin on the surface to which water vapor adheres and permeates is limited to the pores. Therefore, the moisture permeability is lower than in the case where the elastomer resin surface is used on the body side. Further, by using the elastomer resin layer on the body side, there is also an effect that sweat, body fat, and other contaminants generated from the body can be blocked by the elastomer resin layer surface, and the sintered ePTFE membrane can be prevented from being contaminated with contaminants.

Since the fabric surface is usually exposed to the outside surface of the rain gear and used, if the fabric exposed to the outside surface absorbs water, a film of water is formed on the rain gear surface, and not only the moisture permeability of the stretchable composite fabric is impaired, but also the fabric weight is increased and the comfort is deteriorated, and therefore it is preferable to perform water repellency treatment on the outside surface of the fabric with a fluorine-containing water repellent agent, an organic silicon water repellent agent, or the like.

The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples.

(example 1)

Ethylene glycol was added to a hydrophilic urethane resin (HYPOL 2000, trade name, manufactured by Dow chemical Co., Ltd.) in such a ratio that the NCO/OH equivalent ratio became 1, toluene was added under such a condition that the concentration of the urethane prepolymer became 90% by weight, and the mixture was sufficiently mixed and stirred to prepare a coating liquid. The above coating solution was applied to a sintered ePTFE film (thickness: 50 μm, maximum pore diameter: 0.3 μm, porosity: 80%, elongation at break in the transverse direction based on tensile test: 260%) manufactured by ジヤパンゴアテツクス K.K., and cured by heating to obtain a multilayer film in which the thickness of the polyurethane resin layer was 25 μm (thickness of the impregnated portion: 15 μm, thickness of the surface portion: 10 μm). Next, the multilayer film was continuously subjected to stretching treatment in the transverse direction by a device having a tenter tentering in a heating furnace under the conditions shown in table 1, and immediately after stretching, the film was taken out from the tenter, and was allowed to shrink naturally at room temperature while being continuously wound. Further, the film is moved at a constant speed under the condition that the film does not substantially expand or contract in the longitudinal direction.

More specifically, the multilayer film was subjected to a stretching treatment under the conditions of a stretching temperature of 150 ℃, a transverse elongation of 1.5 times, and a stretching speed of 6%/second, to obtain a stretchable composite film. The elongation and the elongation recovery of the resulting stretchable composite film were measured by the methods described above.

As a result, as shown in Table 1, films having an elongation of 35% in the transverse direction, an elongation recovery of 85% and a tensile stress at 10% elongation of 1.5N/15mm were obtained, which were excellent in stretchability. The composite film before the stretching treatment had an elongation in the transverse direction of 10%, a recovery from elongation of 65%, and a tensile stress at 10% elongation of 3.0N/15 mm.

Comparative example 1 Effect of drawing speed

A composite film was produced under the same conditions as in example 1, except that the stretching speed was changed to 1%/second. The composite film obtained had an elongation in the transverse direction of 19%, a recovery from elongation of 80%, and a tensile stress at 10% elongation of 2.6N/15mm, and was poor in stretchability. The evaluation results are shown in Table 1.

Comparative example 2 Effect of stretching temperature

A composite film was produced under the same conditions as in example 1, except that the stretching temperature was set to 220 ℃. The composite film obtained had an elongation of 5% in the transverse direction, a recovery from elongation of 50%, and a tensile stress at 10% elongation of 2.7N/15 mm. Even at the same stretching speed, if the temperature is high, the heat-setting effect is high, and a film having insufficient stretchability is formed. The evaluation results are shown in Table 1.

Comparative example 3 Effect of stretching temperature

The multilayer film was subjected to stretching treatment under the same conditions as in example 1 except that the stretching temperature was set to 90 ℃.

(example 2)

A stretchable composite film was produced under the same conditions as in example 1, except that the stretching temperature was 170 ℃, the elongation percentage in the transverse direction was 1.6 times, and the stretching speed was 13%/second. The evaluation results are shown in Table 1. By increasing the elongation percentage and setting a high stretching speed, a film having good stretchability with an elongation percentage in the transverse direction of 42%, a recovery rate from elongation of 85%, and a tensile stress at 10% elongation of 1.4N/15mm was obtained.

TABLE 1

Numbering	Stretching temperature (. degree.C.)	Transverse elongation factor (times)	Tensile Rate (%/second)	Elongation in transverse direction (%)	Elongation recovery in transverse direction (%)	Stress at 10% elongation (N/15mm)
							Example 1	150	1.5	6	35	85	1.5
Comparative example 1	150	1.5	1	19	80	2.6
							Comparative example 2	220	1.5	6	5	50	2.7
Example 2	170	1.6	13	42	85	1.4

(example 3)

A gravure roll having a transfer area of 40% was used to dot-transfer an adhesive "ボンドマスタ one" from NSC corporation to the sintered ePTFE film surface of the stretchable composite film of example 2, and a woven fabric (nylon/polyurethane elastic fiber mixing ratio 75/25, thickness 28G, weight per unit area of 58G/m) was superposed on the transfer surface²Elongation in the transverse direction was 150%, and elongation recovery rate was 95%), and pressing was performed to obtain a stretchable composite fabric having a 2-layer structure. The resulting stretchable composite fabric had stretch properties of 35% elongation and 93% elongation recovery in the transverse direction. The durability of the adhesion between the laminated film and the back cloth was determined by continuously stirring and washing with tap water without detergent in a heavy duty mode for 100 hours under conditions of a bath ratio of 1/60 and a bath temperature of 45 ℃ or lower using a B-type home washing machine kenmore110.20912 (manufactured by search ROEBUCH andsco) described in ISO 6330, and observing the washed sample with the naked eye to determine the presence or absence of peeling. As a result, no peeling occurred.

Comparative example 4

A stretchable composite membrane was produced under the same conditions as in example 1, except that an unsintered ePTFE membrane was used. Using the resulting stretch composite film, a stretch composite fabric was produced under the same conditions as in example 3. The above-described continuous washing test was performed on the stretchable composite fabric, and as a result, a part of the stretchable composite fabric was peeled off. The peeled portion was observed, and as a result, peeling was observed due to aggregation destruction of the ePTFE layer.

(example 4)

A knitted fabric (nylon/polyurethane elastic fiber mixing ratio 75/25, thickness 28G, basis weight 58G/m) was laminated on the sintered ePTFE film surface of the multilayer film (without stretching treatment) of example 1 under the same conditions as in example 3²Elongation in the transverse direction of 150% and recovery rate of elongation of 95%) to obtain a 2-layer structure laminated fabric except forThe obtained laminated fabric was subjected to a stretching treatment under the same conditions as in example 1 except that the conditions of the stretching temperature of 110 ℃, the elongation factor in the transverse direction of 1.8 times, and the stretching speed of 20%/second were adopted. The results of evaluation of the resulting stretchable composite fabric showed that the fabric had good stretchability with an elongation in the transverse direction of 45%, an elongation recovery of 92%, and a tensile stress at 10% elongation of 1.7N/15 mm.

(example 5)

A knitted fabric (nylon/polyurethane elastic fiber mixing ratio 75/25, thickness 28G, basis weight 58G/m) was laminated on the sintered ePTFE film surface of the multilayer film (without stretching treatment) of example 1 under the same conditions as in example 3²Elongation in the transverse direction was 150% and elongation recovery rate was 95%), and a 2-layer laminated fabric was produced. Then, the same knitted fabric was laminated on the other surface of the multilayer film in the same manner to obtain a laminated fabric having a 3-layer structure. The laminated fabric was subjected to stretching treatment in the same manner as in example 4. The results of evaluation of the resulting stretchable composite fabric showed that the fabric had good stretchability with an elongation in the transverse direction of 35%, an elongation recovery rate of 95%, and a tensile stress at 10% elongation of 2.0N/15 mm.

(example 6)

A woven fabric (2/2 twill structure made of nylon yarn, density: 170X 160 strands/inch, basis weight 82 g/m) was laminated on the sintered ePTFE film surface of the multilayer film (without stretching treatment) of example 1 under the same conditions as in example 3²Transverse elongation of 35% and elongation recovery of 90%), to obtain a 2-layer laminated fabric. The laminated fabric was subjected to a stretching treatment in the same manner as in example 1, except that conditions of a stretching temperature of 150 ℃, a transverse elongation of 1.4 times, and a stretching speed of 20%/second were adopted. The resulting stretchable composite fabric had an elongation in the transverse direction of 25%, an elongation recovery of 88%, and a tensile stress at 10% elongation of 1.96N/15mm, and was a fabric having good stretchability.

(example 7)

The multilayer film of example 1 was subjected to a 1.5-fold stretching treatment at 170 ℃. The stretching speed was set to 5%/second, 1%/second, 0.5%/second, and 0.3%/second. Other conditions were the same as in example 1. The evaluation results of the obtained composite film are shown in fig. 3, and the higher the stretching speed, the higher the elongation of the film.

Claims (9)

1. A method for continuously producing a stretchable composite film comprising a stretched sintered porous film substantially made of polytetrafluoroethylene and an elastomer resin layer formed on at least one surface of the stretched sintered porous film, the method comprising the steps of:

(1) continuously forming the elastomer resin layer on at least one surface of the stretched sintered porous film;

(2) continuously stretching the multilayer film obtained in the above (1) in a biaxial direction or in a uniaxial direction without causing shrinkage in a direction perpendicular to the stretching direction at a stretching ratio of 1.3 times or more which is less than the yield point of the stretched sintered porous film; and

(3) and (3) relaxing the stretched multilayer film obtained in the above (2).

2. A method for continuously producing a stretchable composite fabric in which a stretchable fabric is laminated on one surface or both surfaces of a composite film comprising a stretched sintered porous film substantially made of polytetrafluoroethylene and an elastomer resin layer formed on at least one surface of the stretched sintered porous film, the method comprising the steps of:

(1) continuously forming the elastomer resin layer on at least one surface of the stretched sintered porous film;

(2) a step of continuously laminating a stretchable fabric on one or both surfaces of the multilayer film obtained in the above (1), and a step of continuously stretching the laminated fabric obtained in the laminating step in a biaxial direction at a stretch ratio of 1.3 times or more less than the yield point of the sintered stretched porous film or in a uniaxial direction without shrinking in a direction perpendicular to the stretching direction, or

(2') continuously stretching the multilayer film obtained in the above (1) in a biaxial direction or a uniaxial direction without causing shrinkage in a direction perpendicular to the stretching direction at a stretching magnification of 1.3 times or more less than the yield point of the stretched sintered porous film, and continuously laminating a stretchable fabric on one or both surfaces of the stretched multilayer film obtained in the stretching step; and

(3) and (3) relaxing the stretched laminated fabric obtained in the above (2) or (2').

3. The method according to claim 1, wherein the stretching step is performed under a heating condition of 100 to 200 ℃.

4. The method according to claim 2, wherein the stretching step is performed under a heating condition of 100 to 200 ℃.

5. The production method according to any one of claims 1 to 4, wherein the stretching step is performed at a stretching speed of 5%/second or more.

6. The production method according to any one of claims 1 to 4, wherein the relaxation step is performed at 100 ℃ or lower.

7. The method according to claim 5, wherein the relaxation step is performed at 100 ℃ or lower.

8. A stretchable composite film comprising a stretched sintered porous film and an elastomer resin layer, the method for producing the stretched porous film comprises continuously forming the elastomer resin layer on at least one surface of a stretched sintered porous film substantially made of polytetrafluoroethylene, continuously stretching the obtained multilayer film in a biaxial direction at a stretch ratio of 1.3 times or more less than the yield point of the stretched sintered porous film or in a uniaxial direction without causing shrinkage in a direction perpendicular to the stretching direction, and then relaxing the obtained stretched multilayer film, characterized in that the tensile stress of the composite film at 10% elongation in the longitudinal and/or transverse direction is 2.5N/15mm or less, and/or the composite film has an elongation in the longitudinal and/or transverse direction of 30% or more and a recovery from elongation of 70% or more.

9. A stretchable composite fabric comprising a stretch-sintered porous film, an elastomer resin layer and a stretchable fabric, and a process for producing the stretchable composite fabric, which comprises

(1) A step of continuously forming the elastomer resin layer on at least one surface of a stretched sintered porous film substantially made of polytetrafluoroethylene,

(2) a step of continuously laminating a stretchable fabric on one or both surfaces of the multilayer film obtained in the above (1), and a step of continuously stretching the laminated fabric obtained in the laminating step in a biaxial direction at a stretch ratio of 1.3 times or more less than the yield point of the sintered stretched porous film or in a uniaxial direction without shrinking in a direction perpendicular to the stretching direction, or

(2') a step of continuously stretching the multilayer film obtained in the above (1) in a biaxial direction or a uniaxial direction without causing shrinkage in a direction perpendicular to the stretching direction at a stretching magnification of 1.3 times or more less than the yield point of the stretched sintered porous film, a step of continuously laminating a stretchable fabric on one or both surfaces of the stretched multilayer film obtained in the stretching step, and

(3) a step of relaxing the stretched laminated fabric obtained in the above (2) or (2');

characterized in that the tensile stress at 10% elongation in the longitudinal and/or transverse direction of the composite fabric is 2.5N/15mm or less, and/or the elongation in the longitudinal and/or transverse direction of the composite fabric is 30% or more and the elongation recovery rate is 70% or more.