Method for manufacturing laminate, laminate, and airbag

Abstract

The present disclosure provides a method for manufacturing a laminate comprising a base fabric and a thermoplastic film, in which the thermoplastic film is a multilayer film having an adhesive layer comprising a thermoplastic polyester-based elastomer and an air-tight layer comprising a thermoplastic polyester-based elastomer, the present invention relates to a method for manufacturing a multilayer film comprising an adhesive layer, an inner liner bonded to the adhesive layer, having a melting point higher than the melting point of the adhesive layer, and containing a polymer, and a base fabric containing a polyester, the method comprising a step of adhering the multilayer film to the base fabric on the adhesive layer side while heating at a temperature lower than the melting point of the inner liner. The invention also provides the laminated body manufactured by the manufacturing method of the laminated body and an airbag using the laminated body.

Description

[0001] This application is a divisional application of the invention patent application with an application date of June 15, 2018, an application number of 201880039602.4, and an invention title of "Method for manufacturing a laminate, laminate, and airbag". Technical Field

[0002] The present invention relates to a method for manufacturing a laminate, a laminate, and an airbag (also referred to as a safety airbag). Background Art

[0003] Previously, as a material used in vehicle airbags, outdoor goods, packaging applications, etc., a laminate having a base fabric and a layer of a polymer formed on the base fabric has been well-known. As a method for manufacturing such a laminate, a method of bonding a polymer film to a base fabric has also been well-known.

[0004] For example, Patent Document 1 discloses a technique of laminating a thermoplastic elastomer on a fabric made of thermoplastic resin fibers.

[0005] In addition, Patent Document 2 also discloses a technique in which at least one of a discharge treatment and an ultraviolet treatment is performed on the surface of a fabric, and then a thermoplastic elastomer is applied or laminated on the treated surface via an adhesive.

[0006] [Prior Art Documents]

[0007] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Laid-Open No. 2-114035

[0009] [Patent Document 2] Japanese Patent Laid-Open No. 5-338092 Summary of the Invention

[0010] [Problems to be Solved by the Invention]

[0011] However, in the invention of Patent Document 1, the thermoplastic elastomer to be laminated is a single layer. Therefore, when laminating the thermoplastic elastomer by heating, it is difficult to adjust the temperature, and there are cases where the airtightness of the elastomer layer cannot be ensured and good adhesion between the thermoplastic elastomer and the fabric cannot be obtained. On the other hand, in the case of laminating using an adhesive, the application of the adhesive is time-consuming and laborious, and the cost is also high.

[0012] In addition, in the invention of Patent Document 2, an adhesive is also used when bonding the thermoplastic elastomer, so it is also time-consuming and laborious, and the cost is also high.

[0013] In view of the above problems, an object of one aspect of the present invention is to provide a method for producing a laminate by bonding a base fabric and a thermoplastic film, which can obtain a good bonding effect between the base fabric and the thermoplastic film, is time-saving and labor-saving, and has a low cost.

[0014] [Means for Solving the Problems]

[0015] To solve the above problems, one aspect of the present invention is a method for producing a laminate including a base fabric and a thermoplastic film. The thermoplastic film is a multilayer film having an adhesive layer including a thermoplastic polyester-based elastomer and an airtight layer joined to the adhesive layer and containing a polymer, and the melting point of the airtight layer is higher than that of the adhesive layer. The production method includes a step of bonding the multilayer film to the base fabric on one side of the adhesive layer while heating at a temperature lower than the melting point of the airtight layer. The base fabric includes filaments containing polyester.

[0016] [Advantages of the Invention]

[0017] According to one embodiment of the present invention, in a method for producing a laminate by bonding a base fabric and a thermoplastic film, a good bonding effect between the base fabric and the thermoplastic film can be obtained, and it is time-saving and labor-saving, and the cost is also low. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic cross-sectional view of the thermoplastic film used in one aspect of the present invention.

[0019] Figure 2 Schematic cross-sectional view of a laminate based on one aspect of the present invention.

[0020] Figure 3 Schematic cross-sectional view of a laminate based on one aspect of the present invention.

[0021] Figure 4 Schematic view of an apparatus for producing a laminate based on one aspect of the present invention.

[0022] Figure 5 Schematic view for explaining the lamination of the base fabric and the multilayer film in the production step of a laminate based on one aspect of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] ​​​​​A manufacturing method according to one embodiment of the present invention is a method of laminating and bonding a base fabric and a thermoplastic film. The thermoplastic film has an airtight layer containing a polymer and an adhesive layer containing a thermoplastic polyester-based elastomer, and the melting point of the airtight layer is higher than that of the adhesive layer. Further, while heating at a temperature lower than the melting point of the airtight layer, the thermoplastic film is laminated and bonded to the base fabric on the side of the adhesive layer. For this purpose, not only the airtightness of the airtight layer can be ensured, but also the adhesive layer can be softened, so that the thermoplastic film can be bonded to the base fabric.

[0024] It should be noted that in this specification, "film" refers to a flexible thin film, regardless of its state such as temperature and hardness. Therefore, the thermoplastic film supplied in the above manufacturing method can be a film below room temperature, a film having a temperature higher than room temperature, or a film in a state where at least a part of it can exhibit an adhesive function by being softened. Further, "while heating at a temperature lower than the melting point of the airtight layer, the thermoplastic film is laminated and bonded to the base fabric on the adhesive layer side" includes, for example, bonding a thermoplastic film supplied below room temperature to the base fabric while heating at a temperature lower than the melting point of the airtight layer by a heating unit, or includes, for example, bonding a polymer heated by an extruder and extruded into a film shape to the base fabric.

[0025] (Thermoplastic film)

[0026] Figure 1 It is a schematic cross-sectional view of the thermoplastic film 1 used in the manufacturing method of this embodiment. As Figure 1 shown, the thermoplastic film 1 is a multilayer film and has an airtight layer 2 and an adhesive layer 3 joined to the airtight layer 2. The manufacturing method according to this embodiment includes the step of bonding such a thermoplastic film 1 to a base fabric. At this time, the adhesive layer 3 is on the side bonded to the base fabric. The adhesive layer 3 contains a thermoplastic polyester-based elastomer, the airtight layer 2 contains a polymer, and the melting point of the airtight layer 2 is higher than that of the adhesive layer 3.

[0027] In this specification, the airtight layer refers to a layer having a function of preventing gas from flowing inside and outside the layer. Further, the adhesive layer refers to a layer having adhesiveness to the base fabric, and this adhesiveness can be obtained by being softened or melted under predetermined conditions, for example, under conditions where the temperature and / or pressure are increased. When a multilayer film is bonded to a base fabric to form a laminate, the adhesive layer is directly laminated on the base fabric, and in the laminate, the layer sandwiched between the base fabric and the airtight layer is the inner layer. Therefore, the adhesive layer can also be referred to as a layer that joins the airtight layer and the base fabric.

[0028] The multilayer film has a structure of at least two layers including an airtight layer and an adhesive layer. Accordingly, each layer can have an adhesive function when the film is adhered to the base fabric and an airtight function of the obtained laminate. By using such a multilayer film, compared with the case of adhering a single-layer film to the base fabric, a high-quality laminate having both adhesiveness to the base fabric (interlayer peel resistance between the base fabric and the thermoplastic film) and airtightness can be produced.

[0029] In addition, the melting point of the airtight layer is higher than that of the adhesive layer. For this reason, by heating the multilayer film at a temperature lower than the melting point of the airtight layer and adhering it to the base fabric on the adhesive layer side, softening of the airtight layer can be suppressed, and the adhesive layer can be softened or melted to a softness suitable for adhesion to the base fabric. Accordingly, not only can the adhesive function of the adhesive layer be effectively exerted, but also softening of the airtight layer can be suppressed, and furthermore, the airtight function of the airtight layer can be maintained. Therefore, reliable adhesion to the base fabric can be achieved, and the airtightness of the multilayer film can also be maintained.

[0030] Regarding the multilayer film based on this embodiment, as described above, good adhesion to the base fabric can be achieved only by heating without using an adhesive or the like, so the labor and cost caused by the use of an adhesive can be reduced. In addition, in the case of long-term use or use in a high-temperature and high-humidity environment, disappearance of the flexibility of the laminate, interlayer peeling, etc. caused by deterioration of the adhesive can also be prevented.

[0031] In this specification, the melting point of a layer refers to the temperature described below, that is, when the temperature of the layer is raised to this temperature, the layer softens, relative movement begins between the molecules of the polymer in the layer, and the polymer exhibits fluidity. Therefore, regarding the melting points of the adhesive layer and the airtight layer, they can be respectively referred to as the melting points of the polymers (including polymer alloys) in the adhesive layer and the airtight layer. The melting point of such a polymer can be the melting peak temperature measured by a differential scanning calorimeter.

[0032] (Adhesive layer)

[0033] In this embodiment, the adhesive layer contains a thermoplastic elastomer. Specifically, it contains a thermoplastic polyester-based elastomer. The thermoplastic elastomer is preferably a block copolymer containing a hard segment (also called a high melting point segment or a crystalline segment) and a soft segment (also called a low melting point segment or an amorphous segment). The thermoplastic elastomer can exhibit fluidity by heating and softening, and can exhibit rubber-like elasticity in a state without heating.

[0034] By using a thermoplastic polyester-based elastomer in the adhesive layer, the interlayer peel resistance of the laminate can be improved. That is, the adhesiveness between the adhesive layer and the base fabric and the adhesiveness between the adhesive layer and the airtight layer can be improved both at normal temperature and under conditions of high temperature and / or high humidity. In particular, in this embodiment, an adhesive layer containing a thermoplastic polyester-based elastomer and a base fabric containing polyester are combined, so a laminate having excellent interlayer peel resistance can be obtained. In addition, the flexibility and / or mechanical strength of the laminate can also be improved.

[0035] Regarding the thermoplastic polyester-based elastomer, it can be a polyester-polyether type elastomer that mainly contains an aromatic polyester, etc. as the hard segment and mainly contains an aliphatic polyether, etc. as the soft segment, or it can be a polyester-polyester type elastomer that mainly contains an aromatic polyester, etc. as the hard segment and mainly contains an aliphatic polyester, etc. as the soft segment.

[0036] The hard segment of the thermoplastic polyester-based elastomer preferably contains a block of polyester formed from an aromatic polyester, for example, an aromatic dicarboxylic acid component and a diol component.

[0037] Examples of the aromatic dicarboxylic acid that becomes the aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, anthracene dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, diphenoxyethane dicarboxylic acid, 4,4'-biphenyl ether dicarboxylic acid, 5-sulfoisophthalic acid, sodium 3-sulfoisophthalate, etc. Regarding these aromatic dicarboxylic acid components, one of them can be contained in the aromatic polyester, or a combination of two or more of them can be contained. In addition, in the hard segment, a part of the above aromatic dicarboxylic acid component can also be replaced with an alicyclic or aliphatic carboxylic acid.

[0038] As the diol component that becomes the diol, diols having a molecular weight of 400 or less can be cited. For example, aliphatic diols such as 1,4-butanediol, ethylene glycol, trimethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, decamethylene glycol, etc., alicyclic diols such as 1,1-cyclohexane dimethanol, 1,4-dicyclohexanedimethanol, tricyclodecane dimethanol, etc., aromatic diols such as xylylene glycol, bis(p-hydroxy)diphenyl, bis(p-hydroxy)diphenyl propane, 2,2'-bis[4-(2-hydroxyethoxy)phenyl]propane, bis[4-(2-hydroxyethoxy)phenyl]sulfone, 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 4,4'-dihydroxy-p-terphenyl, 4,4'-dihydroxy-p-quarterphenyl, etc. Regarding these diol components, one of them can be contained in the aromatic polyester, or a combination of two or more of them can be contained.

[0039] Regarding the polyester contained in the hard segment, from the viewpoints of heat resistance and gas barrier properties, polybutylene terephthalate, polyethylene terephthalate, and polytrimethylene terephthalate are preferred, and polybutylene terephthalate is more preferred.

[0040] The soft segment of the thermoplastic polyester-based elastomer preferably contains an aliphatic polyether and / or an aliphatic polyester. Examples of the aliphatic polyether include poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol (polytetramethylene ether glycol), poly(hexamethylene oxide) glycol, a copolymer of ethylene oxide and propylene oxide, an ethylene oxide addition polymer of poly(propylene oxide) glycol, a copolymer glycol of ethylene oxide and tetrahydrofuran, etc. In addition, examples of the aliphatic polyester include poly(ε-caprolactone), polyenanthractone, polycaprolactone, polybutylene adipate, polyethylene adipate, etc.

[0041] Among these aliphatic polyethers and / or aliphatic polyesters, from the viewpoints of elasticity and / or formability, poly(tetramethylene oxide) glycol, an ethylene oxide addition polymer of poly(propylene oxide) glycol, a copolymer glycol of ethylene oxide and tetrahydrofuran, poly(ε-caprolactone), polybutylene adipate, polyethylene adipate, etc. are preferred, and among these, poly(tetramethylene oxide) glycol (polytetramethylene ether glycol), an ethylene oxide addition polymer of poly(propylene oxide) glycol, and a copolymer glycol of ethylene oxide and tetrahydrofuran are particularly preferred.

[0042] The number-average molecular weight of the soft segment is preferably about 300 to 6000 in the copolymerized state.

[0043] It should be noted that the above-mentioned thermoplastic polyester-based elastomer can also be modified by unsaturated carboxylic acids such as acrylic acid, maleic acid, fumaric acid, etc. or their derivatives in the presence of a radical generating agent. Regarding the unsaturated carboxylic acid or its derivative added for modification, it is preferably 0.1 to 30 parts by weight relative to 100 parts by weight of the thermoplastic polyester-based elastomer. Regarding the type and weight of such components for modification, appropriate selection can be made according to the material and / or use of the base fabric to be bonded.

[0044] Regarding the content ratio of the hard segment in the thermoplastic polyester-based elastomer of the adhesive layer, it is preferably 10 to 60% by mass, more preferably 20 to 40% by mass relative to 100% by mass of the thermoplastic polyester-based elastomer. By being 10% by mass or more, the mechanical strength, heat resistance, and durability under high temperature and high humidity of the multilayer film and the laminate can be improved. In addition, by being 60% by mass or less, the multilayer film and the laminate can be ensured to have appropriate elasticity, flexibility, and formability.

[0045] Regarding the content ratio of the soft segment in the thermoplastic polyester-based elastomer of the adhesive layer, it is preferably 50 to 90% by mass, more preferably 60 to 80% by mass relative to 100% by mass of the thermoplastic polyester-based elastomer. By being 50% by mass or more, the appropriate elasticity, flexibility, and formability of the multilayer film and the obtained laminate can be ensured. In addition, by being 90% by mass or less, the mechanical strength of the multilayer film and the obtained laminate can be improved.

[0046] The content ratio of the soft segment in the thermoplastic polyester-based elastomer is related to the melting point and / or softening point of the thermoplastic polyester-based elastomer. Generally, the larger the content ratio of the soft segment in the thermoplastic polyester-based elastomer, the lower the melting point and / or softening point of the thermoplastic polyester-based elastomer. Therefore, by adjusting the content ratio of the soft segment in the thermoplastic polyester-based elastomer of the adhesive layer, the melting point of the thermoplastic polyester-based elastomer can be adjusted, and even the melting point of the adhesive layer can be adjusted.

[0047] The melting point of the thermoplastic polyester-based elastomer used in the adhesive layer is preferably 80 °C or higher, more preferably 100 °C or higher, and still more preferably 130 °C or higher. In addition, regarding the upper limit of the melting point of the thermoplastic polymer used in the adhesive layer, as long as it is a temperature lower than the melting point of the gas barrier layer, there is no particular limitation, and it is preferably 250 °C or lower, more preferably 200 °C or lower, and still more preferably 170 °C or lower.

[0048] The adhesive layer may contain two or more of the above-mentioned thermoplastic polyester-based elastomers. In addition, in addition to the thermoplastic polyester-based elastomers, other thermoplastic elastomers that are not polyester-based may also be included. For example, one or more of polyamide elastomers, polyolefin elastomers, polyurethane elastomers, polystyrene elastomers, polybutadiene elastomers, etc. may be included. In addition, other polymers that are not elastomers may also be included. For example, one or more of polyester resins, polyamide resins, polyolefin resins, polystyrene resins, ethylene-vinyl acetate copolymers, etc. may be included.

[0049] Examples of commercial products of thermoplastic polyester-based elastomers include various series of "Hytrel (registered trademark)" manufactured by Toray DuPont Co., Ltd., "Primalloy (registered trademark)" manufactured by Mitsubishi Chemical Corporation, and "Perprene (registered trademark)" manufactured by Toyobo Co., Ltd.

[0050] Other components in addition to the polymer may also be added to the adhesive layer. Examples of other components include additives such as pigments, fillers, antioxidants, hydrolysis stabilizers, and anti-blocking agents.

[0051] The thickness of the entire adhesive layer is preferably 5 to 50 μm, more preferably 5 to 30 μm.

[0052] (Airtight layer)

[0053] The airtight layer contains a polymer, preferably a thermoplastic polymer. Further, from the viewpoint of improving the elasticity and / or mechanical strength of the obtained laminate, the airtight layer preferably contains a thermoplastic elastomer of polyester-based, polyamide-based, polyolefin-based, polyurethane-based, polystyrene-based, polybutadiene-based, and preferably contains a thermoplastic polyester-based elastomer. When the thermoplastic polyester-based elastomer is contained in the airtight layer, it can be selectively used from among the thermoplastic polyester-based elastomers in the adhesive layer already described.

[0054] When the same type of thermoplastic elastomer is used in the airtight layer and the adhesive layer, for example, when the thermoplastic polyester-based elastomer is used in both the airtight layer and the adhesive layer, the bonding between the airtight layer and the adhesive layer is stronger, and the mechanical strength of the entire multilayer film can also be improved. Further, when the laminate is formed by bonding to the base fabric, the mechanical strength of the entire laminate can also be improved. Regarding the interfacial bonding force between the airtight layer and the adhesive layer, it can be improved even after long-term storage and / or after storage at high temperature and high humidity at room temperature.

[0055] Further, when the thermoplastic polyester-based elastomer is used in the airtight layer and the adhesive layer, regarding the type of hard segment in the thermoplastic polyester-based elastomer used in the airtight layer and the type of hard segment in the thermoplastic polyester-based elastomer used in the adhesive layer, they can be the same as each other or different from each other. Further, regarding the type of soft segment in the thermoplastic polyester-based elastomer used in the airtight layer and the type of soft segment in the thermoplastic polyester-based elastomer used in the adhesive layer, they can be the same as each other or different from each other. Additionally, regarding the type of hard segment and soft segment in the thermoplastic polyester-based elastomer used in the airtight layer and the type of hard segment and soft segment in the thermoplastic polyester-based elastomer used in the adhesive layer, they can be the same as each other or different from each other, respectively. When the types of segments are the same as each other, the bonding force between the airtight layer and the adhesive layer is stronger, and delamination within the multilayer film is less likely to occur, so the mechanical strength of the multilayer film and the laminate can be further improved.

[0056] The melting point of the polymer used in the airtight layer can be a temperature higher than the melting point of the adhesive layer. Therefore, by heating the multilayer film at a temperature lower than the melting point of the airtight layer and bonding it to the base fabric, even if softening or melting causes the adhesive layer to have an adhesive function, deformation or deterioration of the airtight layer can be prevented, and thus the airtight function of the airtight layer can be maintained.

[0057] As described above, although the melting point of the airtight layer is higher than that of the adhesive layer, the difference between the melting point of the airtight layer and the melting point of the adhesive layer is preferably 10 to 100 °C, more preferably 20 to 80 °C, and even more preferably more than 20 °C. In the method based on this embodiment, since heat is used to bond the multilayer film to the base fabric, by setting the difference between the melting point of the airtight layer and the melting point of the adhesive layer within the above range, the temperature can be easily controlled. For this reason, defective products caused by "the adhesive layer not being sufficiently softened and thus unable to exert the bonding function" or "the airtight layer being softened and then deformed or deteriorated, etc., resulting in impaired airtightness" can be prevented, and the production stability can be improved.

[0058] There is no particular limitation on the melting point of the airtight layer, but it is preferably 100 °C or higher, more preferably 150 °C or higher, and even more preferably 180 °C or higher. In addition, there is no particular limitation on the upper limit of the melting point of the thermoplastic polymer used in the airtight layer, but in consideration of the ease of operation during the formation of the multilayer film, it is preferably 300 °C or lower, more preferably 270 °C or lower, and even more preferably 230 °C or lower.

[0059] When the airtight layer contains a thermoplastic polyester elastomer, regarding the content ratio of the hard segment in the thermoplastic polyester-based elastomer, it is preferably 40 to 95% by mass, more preferably 60 to 90% by mass, relative to 100% by mass of the thermoplastic polyester-based elastomer. By being 40% by mass or more, the mechanical strength, heat resistance, and resistance under high temperature and high humidity of the multilayer film and the laminate can be improved. In addition, by being 95% by mass or less, the multilayer film and the laminate can be ensured to have appropriate elasticity, flexibility, and formability.

[0060] In addition, in the above case, regarding the content ratio of the soft segment in the thermoplastic polyester-based elastomer of the airtight layer, it is preferably 5 to 60% by mass, more preferably 10 to less than 50% by mass, relative to 100% by mass of the thermoplastic polyester-based elastomer. By being 5% by mass or more, the multilayer film and the laminate can be ensured to have appropriate elasticity, flexibility, and formability. By being 60% by mass or less, the mechanical strength, heat resistance, and resistance under high temperature and high humidity of the multilayer film and the laminate can be improved.

[0061] It should be noted that regarding the ratio (Psa / Pss) of the content ratio (Psa) of the soft segment in the thermoplastic polyester-based elastomer of the adhesive layer to the content ratio (Pss) of the soft segment in the thermoplastic polyester-based elastomer of the airtight layer, it is preferably 1.2 to 5, more preferably 1.4 to 3.5. By being within the above range, the production stability can be improved. In addition, it can also have mechanical strength and / or heat resistance, and a multilayer film and a laminate with excellent elasticity, softness, etc. can be obtained.

[0062] The airtight layer may contain two or more of the above-mentioned thermoplastic polyester-based elastomers. In addition, the airtight layer may be mixed with other thermoplastic elastomers that are not polyester-based, and may also be mixed with polymers that are not elastomers.

[0063] Similar to the adhesive layer, other components besides polymers may also be added to the airtight layer. As other components, additives such as pigments, fillers, antioxidants, hydrolysis stabilizers, and anti-sticking agents can be cited.

[0064] The overall thickness of the airtight layer is preferably 5 to 50 μm, more preferably 5 to 30 μm.

[0065] (Layer structure of the multilayer film)

[0066] As described above, the thermoplastic film (multilayer film) has an airtight layer and an adhesive layer. The adhesive layer may be one layer or multiple (plural) layers. In the case where the adhesive layer is multiple layers, the materials constituting each adhesive layer may be the same or different. In addition, the melting points of the respective layers of the multiple adhesive layers may be the same or different. Similarly, the airtight layer may be one layer or multiple layers. In the case where the airtight layer is multiple layers, the materials and melting points of each airtight layer may be the same or different respectively.

[0067] As a specific structure, a multilayer film in which the first adhesive layer, the second adhesive layer, and the airtight layer are laminated in this order may be formed. In this case, a pigment or the like may be added to any one of the first adhesive layer and the second adhesive layer. With such a configuration, the amount of pigment used can be reduced, and furthermore, the manufacturing cost of the laminate can be lowered.

[0068] In addition, the adhesive layer may be three layers, and a multilayer film in which the first adhesive layer, the second adhesive layer, the third adhesive layer, and the airtight layer are laminated in this order may be formed. Alternatively, the airtight layer may be two layers, and a multilayer film in which the first adhesive layer, the second adhesive layer, the first airtight layer, and the second airtight layer are laminated in this order may be formed.

[0069] (Manufacture of the multilayer film)

[0070] The multilayer film can be manufactured by joining the adhesive layer and the airtight layer. In this case, the adhesive layer and the airtight layer may be made into sheets or films in advance, formed by extrusion molding or the like, and then joined to each other to be integrated. For example, methods such as overlapping the respective sheets or films and then performing melt bonding by hot pressing or hot rolling, and the extrusion lamination method of extruding the melted material onto the formed sheet or film can be cited.

[0071] In addition, the materials of the respective layers of the adhesive layer and the airtight layer can be made into a molten state and simultaneously extrusion molded (co-extrusion), and molding can be performed using an inflation molding method, a T-die method, or the like. Among these, the inflation method, which enables large-area formation and has excellent productivity, is preferably used.

[0072] (Base fabric)

[0073] In this specification, the base fabric refers to a sheet-like structure that functions as a support for ensuring the strength of the laminate as the final product obtained by laminating a multilayer film and the base fabric. Here, the sheet-like shape means a planar shape, but may also include other shapes formed into a cylindrical shape, a bag shape, or a balloon shape.

[0074] The base fabric is preferably a base fabric containing fibers, and can be a fabric, a knitted fabric, a non-woven fabric, etc., and can be sewn integrally or partially. Among these, a fabric is preferred because of its high mechanical strength, and a biaxial structure in which a plurality of warp threads and a plurality of weft threads are combined is preferred, and a triaxial structure in which a plurality of warp threads, a plurality of weft threads, and a plurality of bias threads are combined can also be used. Among these, a biaxial structure base fabric is preferred, and a plain woven fabric is better from the viewpoints of strength and ease of production. In addition, the base fabric may also include an integral woven fabric (One Piece Woven) that is not a planar base fabric but is woven into a bag shape without seams in a manner that matches the shape of the product for the intended use and has a curved surface.

[0075] The above-mentioned OPW can be preferably used for applications such as airbags that expand by internal inflation. Among these, the OPW for a curtain airbag has a complex curved surface with a plurality of small chambers formed, and may have a structure that forms irregularities when inflated. Generally, when bonding a film to a base fabric having such an irregular structure, peeling is more likely to occur between the base fabric and the film than when bonding a film to a base fabric without irregularities. However, by using the multilayer film based on this form, even for an OPW with irregularities, the multilayer film can be bonded well, and interlayer peeling can be prevented.

[0076] As the polymer constituting the fiber, preferably include homopolyesters such as polyalkylene terephthalate such as polyethylene terephthalate and polybutylene terephthalate, and polyester fibers in which an aliphatic dicarboxylic acid such as isophthalic acid, 5-sodium sulfoisophthalic acid, or adipic acid is copolymerized with the acid component of the repeating unit constituting the polyester.

[0077] In addition to polyester fibers, synthetic fibers, natural fibers, regenerated fibers, semi-synthetic fibers, inorganic fibers, and combinations thereof (including blended and mixed weaves) other than polyester fibers may also be contained. As fibers, conjugate fibers such as core-sheath type fibers, side-by-side type fibers, and segmented type fibers may also be used.

[0078] It should be noted that when the base fabric is a fabric, the base fabric may contain two or more types of fibers. For example, as the fibers used in the filaments extending in different directions, different types of fibers may be used respectively. More specifically, in the case of a two-axis structure including warp and weft filaments, the warp and weft filaments may be different types of fibers. In this case, at least one of the warp and weft filaments may be a polyester fiber.

[0079] In the method according to this embodiment, by making the base fabric have fibers containing polyester and making the adhesive layer of the multilayer film contain a thermoplastic polyester-based elastomer, the adhesiveness between the base fabric and the multilayer film can be improved. Accordingly, peeling between the base fabric and the multilayer film in the obtained laminate is not likely to occur.

[0080] Regarding the base fabric, it is preferably formed using filaments having a total fineness (denier per filament × number of filaments) of 100 to 700 dtex. In addition, the denier per filament of the fibers used in the base fabric is preferably 1 to 10 dtex.

[0081] When the base fabric is a plain-woven fabric, as the weaving density, the warp and weft filaments are each preferably 5 to 30 filaments / cm 2 .

[0082] Regarding the unit weight (weight per 1 m 2 ) of the base fabric, in consideration of the storability and cost of the laminate (final product), it is preferably 300 g / m 2 Hereinafter, it is preferably 200 g / m 2 Hereinafter, it is more preferably 190 g / m 2 Hereinafter, it is particularly preferably 150 g / m 2 Hereinafter, it may also be 100 g / m 2 Hereinafter. In addition, from the viewpoint of ensuring mechanical strength, it is preferably 30 g / m 2 Hereinafter, it is preferably 50 g / m 2 Hereinafter, it is more preferably 70 g / m 2 Hereinafter.

[0083] (Laminate)

[0084] Figure 2 It is a cross-sectional view of a laminate according to one embodiment of the present invention. The laminate 5 is formed by adhesively bonding the multilayer film 1 having the airtight layer 2 and the adhesive layer 3 and the base fabric 4 to each other.

[0085] Figure 2 In the example, although multiple layers of film 1 are disposed on the other surface of the base fabric 4, the multiple layers of film of this embodiment can also be disposed on both surfaces of the base fabric 4. Further, in the case where an OPW that is bent into a bag shape without seams is used as the base fabric, as Figure 3 shown, in a state where the air inside the bag is extracted and folded, a structure in which multiple layers of film 1a and 1b are laminated on both surfaces respectively can also be provided. Figure 3 The laminated body shown can be used for an airbag or the like.

[0086] (Method for manufacturing a laminated body)

[0087] The method for manufacturing a laminated body according to one embodiment of the present invention includes a step of bonding the multiple layers of film to the base fabric on one side of the adhesive layer while heating at a temperature lower than the melting point of the airtight layer.

[0088] Figure 4 FIG. is a schematic diagram of a laminated body manufacturing apparatus 20 for implementing the method for manufacturing a laminated body according to this embodiment. Figure 4 Herein, an apparatus for manufacturing a laminated body in which multiple layers of film are laminated on both surfaces of a base fabric 4 will be described. The laminated body manufacturing apparatus 20 includes a heating unit 22 and a cooling unit 24.

[0089] In the method of manufacturing using Figure 4 the laminated body manufacturing apparatus 20, first, the base fabric 4 wound on a reel or the like and the multiple layers of film 1a and 1b are respectively unwound, and the multiple layers of film 1a and 1b are respectively overlapped on both surfaces (the upper surface and the lower surface) of the base fabric 4. Specifically, as shown in the figure, the multiple layers of film 1a having an airtight layer 2a and an adhesive layer 3a are overlapped with the adhesive layer 3a on the side of the base fabric 4. Further, the multiple layers of film 1b having an airtight layer 2b and an adhesive layer 3b are also overlapped with the adhesive layer 3b on the side of the base fabric 4. Then, the overlapped multiple layers of film 1b, the base fabric 4, and the multiple layers of film 1a are fed into the heating unit 22, and are heated and pressed inside the heating unit 22.

[0090] The heating section 22 has a pressing unit formed of, for example, a pair of opposing rollers (nip rollers, etc.) or a pair of opposing belts as shown in the illustrated example. Accordingly, by passing the overlapped multi-layer films 1b, the base fabric 4, and the multi-layer film 1a between such a pair of pressing units, heating and pressing can be performed. Regarding heating and pressing, they can be performed by the same unit as in the illustrated example, or can be performed by different units respectively. Here, since the melting point of the adhesive layer of the multi-layer film is lower than the melting point of the airtight layer, by setting the heating temperature inside the heating section 22 to a temperature lower than the melting point of the airtight layer, the adhesive layer can be pressed against the base fabric in a state where the adhesive layer is sufficiently softened. Accordingly, the multi-layer films 1a and 1b can be respectively adhered to the two surfaces of the base fabric 4, thereby forming a laminate 5 including the multi-layer film 1b, the base fabric 4, and the multi-layer film 1a.

[0091] Next, the laminate 5 that has passed through the heating section 22 is sent to the cooling section 24. In the cooling section 24, it is preferable to lower the temperature of the laminate 5 to room temperature. The cooling section 24 can have a cooling unit containing a cooling medium, a suction unit, etc. In addition, in the cooling section 24, as shown in the illustrated example, a pressing unit formed of a pair of opposing belts can be used for pressing, but pressing is not essential.

[0092] It should be noted that, in Figure 4 the manufacturing apparatus, by omitting either one of the multi-layer films 1a and 1b, a laminate in which the multi-layer film 1 is laminated on one surface of the base fabric 4 as shown in Figure 2 can also be manufactured.

[0093] In addition, as the base fabric 4, a seamless woven tubular or bag-shaped OPW can also be used. Accordingly, a laminate as shown in Figure 3 can be manufactured. In this case, regarding the base fabric 4, air can be drawn out from the inside of the bag-shaped base fabric 4 to make it sheet-shaped, and it can be pre-wound on a reel or the like and then unwound before overlapping. After that, on the upper surface and the lower surface of the base fabric 4, as described above, the multi-layer films 1a and 1b can be respectively overlapped. In this case, since the base fabric 4 is bag-shaped, both the upper surface and the lower surface of the base fabric 4 are the surfaces of the base fabric 4.

[0094] Figure 5 is a schematic diagram of a state in which the multi-layer films 1a, the base fabric 4, and the multi-layer film 1b are overlapped on the upper surface and the lower surface of the base fabric 4 that is put into the laminate manufacturing apparatus 20 in a flat state. As shown in Figure 5 the overlapped multi-layer films 1a, the base fabric 4, and the multi-layer film 1b are pressed from two surfaces by a pair of pressing units in the pressing section 22. Accordingly, as shown in Figure 3As shown, by joining the multilayer films 1a and 1b to the upper surface and the lower surface of the base fabric 4 respectively, and joining the edge portions of the multilayer films 1a and 1b to each other by heating or an adhesive, a laminate (airbag) 6 can be obtained ( Figure 3 ). The excess edge portions can be cut off. In this way, an airbag can be fabricated in which the base fabric is formed into a bag shape and the multilayer film is formed on the surface of the base fabric.

[0095] Regarding the heating temperature during the fabrication of the laminate, as long as it is a temperature above the melting point of the adhesive layer and below the melting point of the airtight layer, there is no particular limitation. The heating temperature can be a temperature below the melting point of the airtight layer and capable of softening the adhesive layer. Specifically, it is preferably 120 to 250 °C. In addition, regarding the pressure of the pressure roller, although it is also affected by the constitution of the multilayer film and the base fabric, it can be 5 to 700 N / cm 2 , preferably 10 to 500 N / cm 2 . Additionally, based on the working conditions during the fabrication of the laminate, etc., it can also be 5 to 50 N / cm 2 .

[0096] As described above, the method for fabricating the laminate according to this embodiment may include a step of bonding the multilayer film to the base fabric on one side of the adhesive layer while heating at a temperature below the melting point of the airtight layer. Here, regarding the step of "bonding while heating at a temperature below the melting point of the airtight layer", it is sufficient as long as it is a step capable of bonding at a temperature below the melting point of the airtight layer. In other words, this step can be referred to as a step of bonding the multilayer film to the base fabric while maintaining the state where the multilayer film is heated at a temperature below the melting point of the airtight layer.

[0097] Therefore, for example, by using a laminate fabricating apparatus that has a conveyance apparatus close to the base fabric and is equipped with a fabricating apparatus for the multilayer film, the laminate can be fabricated. Figure 4 In , for at least one of the multilayer films 1a and 1b, instead of being supplied starting from the state of being wound on a spool, it can be directly supplied from the fabricating apparatus for the multilayer film (an extruder including a T-die, etc.). In this case, regarding the multilayer material that is heated in the extruder and extruded from the extruder into a film shape, it can be supplied in a high-temperature state at least below the melting point of the airtight layer but above room temperature. Next, such a multilayer film can be disposed on the base fabric, and then the multilayer film and the base fabric can be bonded while applying pressure and / or heating or maintaining the temperature as needed.

[0098] It should be noted that the laminate can also be produced by using a laminate production device arranged close to the production device (such as a loom) of the base fabric and the production device of the laminate. That is, on the just woven base fabric, the multilayer films extruded from an extruder or the like are overlapped, and pressure and / or heating or temperature maintenance are performed as required, whereby the laminate can be produced.

[0099] Thus, the method for producing a laminate according to this embodiment may also include a step of bonding the multilayer film to the base fabric on one side of the adhesive layer at a temperature lower than the melting point of the airtight layer.

[0100] (Use)

[0101] The laminate produced by the method according to this embodiment is preferably used in vehicle airbags, outdoor products, packaging applications, etc., and is particularly preferably used in the production of vehicle airbags, especially curtain airbags. A curtain airbag refers to an airbag installed on the roof line (roof line) above the side window or the like, and can be deployed vertically downward in a curtain shape along the side window when a high load is generated during an impact or the like.

[0102] When the curtain airbag is deployed, it needs to maintain an inflated state for several seconds after activation, for example, between 6 and 7 seconds. Therefore, the material of the curtain airbag is required to have pressure resistance. In addition, the curtain airbag is mostly stored in a folded or rolled state in a case or the like for a long time before deployment, and is also often placed in a high temperature and high humidity environment. The multilayer film and laminate of this embodiment are also suitable for such uses.

[0103] In addition, when the laminate of the film and the base fabric is used in a vehicle airbag, various performances are required for safety reasons. Each country has set standards for safety, and these standards tend to become more and more strict. For example, in recent years, the United States has raised the safety standards of airbags. Regarding the durability under high temperature and high humidity, for example, in the past, the temperature and pressure conditions in the high temperature and high humidity adhesion test were 40°C, relative humidity 92%, and 168 hours, but currently it has been changed to the more strict temperature 70°C, relative humidity 95%, and 408 hours. Therefore, the material of the airbag is required to be able to withstand such a strict high temperature and high humidity environment. The laminate produced by the production method according to this embodiment is not easily delaminated between layers even after being stored in such a strict high temperature and high humidity, and shows excellent durability.

[0104] In addition, when making airbags, it is always required to reduce the cost of products. As the material of the base cloth for making airbags, polyamide materials such as nylon have been used in the past, but now relatively low-priced polyester base cloth can be used. For this reason, the base cloth containing polyester silk thread also requires a film material with high adhesion, but the adhesion of the previous film to the polyester base cloth is sometimes insufficient. Although the laminated body of this form has a base cloth containing polyester and a multilayer film, it has a base cloth containing polyester and an adhesive layer containing an airtight layer and a thermoplastic polyester elastomer, and a film with a melting point of the airtight layer higher than the melting point of the adhesive layer is used, so the adhesion between the base cloth and the film is also excellent even under the conditions of normal temperature and high temperature and high humidity.

[0105] [Example]

[0106] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[0107] In this example, a multilayer film including an airtight layer and an adhesive layer was formed, and then the multilayer film was bonded to a base fabric to produce a laminate, which was then evaluated.

[0108] [Raw materials for multilayer films]

[0109] As the raw materials of the multilayer film, the following raw materials were used: The melting point of each raw material is the melting peak temperature measured by a differential scanning calorimeter.

[0110] Thermoplastic polyester elastomer (PTEE-1): a polyester-polyether block copolymer having polybutylene terephthalate as a hard segment and polytetramethylene ether glycol having a number average molecular weight of 2000 as a soft segment. In the above polymer, the content of polybutylene terephthalate is 25% by weight and the content of the polytetramethylene ether glycol block is 75% by weight (melting point is 152°C).

[0111] Thermoplastic polyester elastomer (PTEE-2): a polyester-polyether block copolymer having polybutylene terephthalate as a hard segment and polytetramethylene ether glycol having a number average molecular weight of 2000 as a soft segment. In the above polymer, the content of polybutylene terephthalate is 35% by weight and the content of polytetramethylene ether glycol block is 65% by weight (melting point is 185°C).

[0112] Thermoplastic polyester elastomer (PTEE-3): a polyester-polyether block copolymer having polybutylene terephthalate as a hard segment and polytetramethylene ether glycol with a number average molecular weight of 2000 as a soft segment. In the above polymer, the content of polybutylene terephthalate is 58% by weight, and the content of polytetramethylene ether glycol block is 42% by weight (melting point is 207°C).

[0113] [Evaluation of Multilayer Film and Laminate]

[0114] <Adhesion at Room Temperature (Interlayer Peel Resistance at Room Temperature)>

[0115] A test piece of 50 mm × 150 mm was prepared from a laminate obtained by laminating a multilayer film and a base fabric. With the part of the base fabric of the test piece (laminate) fixed, the force required to tear off the part of the multilayer film (airtight layer and adhesive layer) in the 180° direction at a tensile speed of 100 mm / min was taken as the peel force (N / mm), and it was measured. The evaluation criteria are as follows.

[0116] 〇: The peel force exceeded 0.5 N / mm.

[0117] △: The peel force was 0.3 - 0.5 N / mm.

[0118] ×: The peel force was less than 0.3 N / mm, or interlayer peeling occurred within the multilayer film.

[0119] <Adhesion at High Temperature and High Humidity (Interlayer Peel Resistance at High Temperature and High Humidity)>

[0120] The test piece obtained as described above was placed in a sealed container, and the conditions inside the container were set to a temperature of 70°C and a relative humidity of 95%, and it was held under these conditions for 408 hours. With the part of the base fabric of the test piece (laminate) taken out from the container fixed, the force required to tear off the part of the multilayer film (airtight layer and adhesive layer) in the 180° direction at a tensile speed of 100 mm / min was taken as the peel force (N / mm), and it was measured. The evaluation criteria are as follows.

[0121] 〇: The peel force exceeded 0.5 N / mm.

[0122] △: The peel force was 0.3 - 0.5 N / mm.

[0123] ×: The peel force was less than 0.3 N / mm, or interlayer peeling occurred within the multilayer film.

[0124] It should be noted that when measuring the peel force, in order to prevent the multilayer film from breaking and / or stretching during the peel test, a polyethylene terephthalate film with a thickness of 100 μm was adhered to the airtight layer side of the multilayer film through an adhesive to reinforce it.

[0125] [Example 1]

[0126] (Multilayer Film)

[0127] A multilayer film was produced using an inflation extrusion device (manufactured by Dr Collin) with three extruders. Thermoplastic polyester elastomers (PTEE-1), thermoplastic polyester elastomers (PTEE-1), and thermoplastic polyester elastomers (PTEE-3) were respectively fed into each extruder, melted at temperatures above the melting points of the respective raw materials, and then a three-layer film was produced using the inflation method.

[0128] The obtained film is a three-layer film in which a first adhesive layer made of a thermoplastic polyester elastomer (PTEE-1), a second adhesive layer made of a thermoplastic polyester elastomer (PTEE-1), and an airtight layer made of a thermoplastic polyester elastomer (PTEE-3) are laminated in this order. The extrusion amounts of the first adhesive layer, the second adhesive layer, and the airtight layer are respectively 10 g / m 2 .

[0129] (Lamination of Multilayer Film and Base Fabric)

[0130] As the base fabric, a plain woven base fabric woven from polyethylene terephthalate fibers was used. The total fineness of the warp and weft yarns is 470 dtex, and in terms of the weaving density, the warp and weft yarns are respectively 22 pieces / cm.

[0131] Using a lamination device (manufactured by Mayer, Twin-belt flat lamination system), the above-mentioned PET base fabric and the above-mentioned three-layer film were laminated in such a way that the adhesive layer was in contact with the surface of the base fabric, then heated at a temperature of 200 °C, and pressed by nip rollers to 18 N / cm 2 , so that the above-mentioned adhesive layer was softened, thereby laminating the base fabric and the three-layer film. The adhesion at room temperature and the adhesion after storage at high temperature and high humidity of the obtained laminate were evaluated. The results are shown in Table 1.

[0132] [Example 2]

[0133] (Multilayer Film)

[0134] A three-layer film was produced in the same manner as in Example 1, except that a thermoplastic polyester elastomer (PTEE-2) was used instead of the thermoplastic polyester elastomer (PTEE-1). The obtained film is a three-layer film in which a first adhesive layer made of a thermoplastic polyester elastomer (PTEE-2), a second adhesive layer made of a thermoplastic polyester elastomer (PTEE-2), and an airtight layer made of a thermoplastic polyester elastomer (PTEE-3) are laminated in this order. The extrusion amounts of the first adhesive layer, the second adhesive layer, and the airtight layer are respectively 10 g / m 2 .

[0135] (Lamination of Multilayer Film and Base Fabric)

[0136] A laminate of a base fabric and a multilayer film was produced in the same manner as in Example 1 and evaluated. The results are shown in Table 1.

[0137] [Comparative Example 1]

[0138] (Multilayer Film)

[0139] A three-layer film identical to that of Example 1 was produced.

[0140] (Lamination of Multilayer Film and Base Fabric)

[0141] A laminate was produced by laminating a multilayer film and a base fabric in the same manner as in Example 1, except that the base fabric was changed to a nylon base fabric. The total fineness of the warp and weft yarns of the nylon base fabric used was 470 dtex, and the knitting density was 22 yarns / cm for both the warp and weft yarns. The adhesiveness at room temperature and after storage at high temperature and high humidity was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0142] This application claims priority based on Japanese Patent Application No. 2017-119101 filed with the Japan Patent Office on June 16, 2017, and incorporates the entire contents thereof herein.

[0143] [Table 1]

[0144]

[0145] [Symbol Explanation]

[0146] 1, 1a, 1b Thermoplastic film (multilayer film);

[0147] 2, 2a, 2b Airtight layer;

[0148] 3, 3a, 3b Adhesive layer;

[0149] 4 Base fabric;

[0150] 5 Laminate;

[0151] 6 Laminate (airbag);

[0152] 20 Laminate production apparatus;

[0153] 22 Heating section;

[0154] 24 Cooling section.

Claims

1. A method for manufacturing a laminate comprising a base fabric and a thermoplastic film, wherein: The thermoplastic film is a multilayer film, and the multilayer film has: An adhesive layer containing a thermoplastic polyester-based elastomer; and An airtight layer that is joined to the adhesive layer, has a melting point higher than that of the adhesive layer, and contains a thermoplastic polyester-based elastomer, The multilayer film is formed by simultaneously extruding the materials of each layer of the adhesive layer and the airtight layer in a molten state, The base fabric contains polyester, The method includes: A step of bonding the multilayer film to the base fabric on the side of the adhesive layer while heating at a temperature of 200 to 250 °C, The thermoplastic polyester-based elastomers in the adhesive layer and the airtight layer are block copolymers, the block copolymers contain soft segments and hard segments, the soft segments contain polyethers, the hard segments contain polyesters, and the hard segments and soft segments in the thermoplastic polyester-based elastomer of the airtight layer are the same in kind as the hard segments and soft segments in the thermoplastic polyester-based elastomer of the adhesive layer, Regarding the content ratio of the hard segments in the thermoplastic polyester-based elastomer of the adhesive layer, it is 10 to 60% by mass relative to 100% by mass of the thermoplastic polyester-based elastomer.

2. The manufacturing method according to claim 1, wherein: The base fabric is a base fabric for an airbag.

3. The manufacturing method according to claim 1, wherein: The melting point of the airtight layer is higher than that of the adhesive layer, and the difference between the two melting points exceeds 20 °C.

4. A laminate manufactured by the manufacturing method according to any one of claims 1 to 3.

5. An airbag using the laminate according to claim 4, wherein: The base fabric is formed in a bag shape, and the multilayer film is formed on the surface of the base fabric.

Images