WO2019155925A1

WO2019155925A1 - Hot-melt polyurethane adhesive film and layered fibrous structure

Info

Publication number: WO2019155925A1
Application number: PCT/JP2019/002658
Authority: WO
Inventors: 真人割田; 道憲藤澤
Original assignee: 株式会社クラレ
Priority date: 2018-02-08
Filing date: 2019-01-28
Publication date: 2019-08-15
Also published as: TW201936837A

Abstract

Use is made of a hot-melt polyurethane adhesive film that comprises a first hot-melt polyurethane layer, a second hot-melt polyurethane layer, and a third polyurethane layer, which is interposed between the first hot-melt polyurethane layer and the second hot-melt polyurethane layer, wherein the third polyurethane layer has a higher softening temperature than the first hot-melt polyurethane layer and the second hot-melt polyurethane layer.

Description

Hot melt polyurethane adhesive film and laminated fiber structure

The present invention relates to a hot melt polyurethane adhesive film and a laminated fiber structure in which fiber base materials are bonded to each other using the hot melt polyurethane adhesive film.

Hot melt polyurethane adhesive film is used to bond fiber substrates together. For example, a stack is formed by interposing a hot melt polyurethane adhesive film between a mesh knitted fabric having a low apparent density and a fiber base material such as artificial leather having a higher apparent density than that of the mesh knitted fabric, and the stacked body is hot pressed. Then, an upper material (upper material) for sports shoes, in which artificial leather is bonded to the surface of a mesh knitted fabric, is known.

Conventional hot melt polyurethane adhesive films were designed to melt quickly when a predetermined temperature is reached in a hot pressing process and to solidify rapidly when the temperature falls below a predetermined temperature. For example, Patent Document 1 below is a polyurethane hot melt polyurethane adhesive, whose melt viscosity behavior is sensitive to temperature and flexible at low temperatures, and has a texture, chemical resistance, dry cleaning properties, heat resistance, and adhesive strength. Discloses a thermoadhesive polyurethane film mainly composed of a thermoplastic polyurethane obtained by reacting an aliphatic diisocyanate, an aromatic diisocyanate, a polymer diol, and a chain extender.

Patent Document 2 below discloses an automotive interior material laminating film in which an outer layer and an inner layer are made of a polyethylene resin, and an intermediate layer is made of a synthetic resin having a melting point 30 ° C. higher than that of the polyethylene resin. Patent Document 2 discloses nylon or ethylene-vinyl alcohol copolymer resin as an intermediate layer. However, since the film for bonding mainly composed of polyethylene resin has high rigidity, the fiber structure formed by adhering the mesh knitted fabric and artificial leather having an apparent density higher than that of the mesh knitted fabric becomes harder, and also has moisture permeability. Therefore, it cannot be used practically as a material for sports shoes.

Japanese Patent Laid-Open No. 7-97560 JP-A-7-68721

For example, in order to bond artificial leather with low void density and high apparent density on the surface of a mesh knitted fabric with low fiber density and many voids and low apparent density, a hot melt polyurethane adhesive film is interposed in one step When trying to bond in the hot press process, hot melt polyurethane adhesive penetrates preferentially into the mesh knitted fabric side, and the hot melt polyurethane adhesive does not easily penetrate into the artificial leather side. It was difficult to bond them so as to maintain a high bond strength. For this purpose, first, the hot melt polyurethane adhesive is sufficiently infiltrated into the artificial leather by the first-stage heat press treatment, and then the artificial leather infiltrated with the hot melt polyurethane adhesive is overlaid on the surface of the mesh knitted fabric. It was necessary to devise processes in order to maintain the high adhesive strength by controlling the distribution of the hot melt polyurethane adhesive between the two materials by performing the heat press treatment of the eyes.

The present invention is a hot melt polyurethane adhesive that can easily adhere while maintaining high adhesive strength when adhering substrates having different apparent densities that are likely to have a difference in penetration of the hot melt polyurethane adhesive. It is an object of the present invention to provide an adhesive film and a laminated fiber structure in which fiber substrates having different apparent densities are bonded to each other as an adherend substrate.

One aspect of the present invention is a third polyurethane interposed between a first hot melt polyurethane layer, a second hot melt polyurethane layer, and the first hot melt polyurethane layer and the second hot melt polyurethane layer. And a softening temperature of the third polyurethane layer is higher than the softening temperatures of the first hot melt polyurethane layer and the second hot melt polyurethane layer. According to such a hot-melt polyurethane adhesive film, by disposing the third polyurethane layer having a high softening temperature between the first hot-melt polyurethane layer and the second hot-melt polyurethane layer that contributes to adhesion. The third polyurethane layer becomes a barrier layer that suppresses mixing of the first hot-melt polyurethane layer and the second hot-melt polyurethane layer by the force applied at the time of adhesion when heated, and the first hot-melt polyurethane layer Each of the polyurethane layer or the second hot melt polyurethane layer penetrates only to the adherend substrate facing each other. Thereby, the hot melt polyurethane of each hot melt polyurethane layer can be sufficiently permeated into each adherend substrate, and high adhesive strength can be maintained.

Further, the softening temperature of the third polyurethane layer is 20 ° C. or more higher than the softening temperature of the first hot melt polyurethane layer. It is preferable from the point that the melt polyurethane layer can sufficiently penetrate.

Further, the first hot melt polyurethane layer has a softening temperature of 20 ° C. higher than the softening temperature of the first hot melt polyurethane layer and the softening temperature of the second hot melt polyurethane layer. The first hot-melt polyurethane layer can sufficiently penetrate into the adherend substrate facing, and the second hot-melt polyurethane layer can sufficiently penetrate into the adherend substrate facing the second hot-melt polyurethane layer. It is preferable from the point.

In addition, when the softening temperature of the first hot melt polyurethane layer is higher by 5 ° C. or more than the softening temperature of the second hot melt polyurethane layer, the first hot melt polyurethane layer has a low apparent density. By facing the second hot melt polyurethane layer and facing the adherend substrate having a high apparent density, it is preferable from the viewpoint that each hot melt polyurethane layer can enter the adherend substrate in a well-balanced manner.

In addition, when the thickness of the third polyurethane layer is 10 to 110 μm, it is difficult to break by maintaining sufficient strength in the hot press process, and the laminated fiber structure obtained by bonding the substrates to be bonded together This is preferable from the viewpoint of not curing the texture of the body.

Further, the 100% modulus at 25 ° C. of the third polyurethane layer is preferably 2 to 7 MPa from the viewpoint of not curing the texture of the laminated fiber structure obtained by bonding the adherend substrates together.

Further, it is preferable that the storage elastic modulus E ′ at 140 ° C. of the third polyurethane layer is 2 to 30 MPa from the viewpoint of exhibiting a sufficient barrier effect that is not easily broken during hot pressing.

Another aspect of the present invention includes a first hot melt polyurethane layer and a second hot melt polyurethane layer, and the first hot melt polyurethane layer has a softening temperature of the second hot melt polyurethane layer. Higher hot melt polyurethane adhesive film. According to such a hot melt polyurethane adhesive film, the first hot melt polyurethane layer is made to face the adherend substrate having a low apparent density, and the second hot melt polyurethane layer is made to have a high apparent density. By facing each other, each hot melt polyurethane layer can be penetrated into each adherend substrate in a well-balanced manner, which is preferable.

Further, another aspect of the present invention is a laminated fiber structure in which two fiber base materials having different apparent densities are bonded to each other with the hot melt polyurethane adhesive film. According to such a laminated fiber structure, high adhesive strength between two fiber base materials having different apparent densities can be maintained. In particular, fiber substrates that have a large difference in apparent density such that the apparent density of one of the two fiber substrates is 1.5 times or more the apparent density of the other fiber substrate. Even when these are bonded, high adhesive strength can be maintained.

According to the present invention, a hot melt polyurethane adhesive film that can easily maintain high adhesive strength when bonding adherend substrates having different apparent densities, and two different apparent densities using the hot melt polyurethane adhesive film can be maintained. A laminated fiber structure in which a fiber base material is bonded and a high adhesive strength is maintained is obtained.

FIG. 1 is a schematic cross-sectional view of a hot-melt polyurethane adhesive film 10 of the first embodiment. FIG. 2 is a schematic explanatory view for explaining a state when fiber substrates having different apparent densities are bonded using the hot-melt polyurethane adhesive film 10. FIG. 3 is a schematic cross-sectional view of the hot melt adhesive film 30 of the second embodiment.

[First Embodiment]
The hot melt polyurethane adhesive film of 1st Embodiment is demonstrated with reference to drawings. FIG. 1 is a schematic cross-sectional view of a hot-melt polyurethane adhesive film 10 of the first embodiment. As shown in FIG. 1, the hot melt adhesive film 10 includes a first hot melt polyurethane layer 1, a second hot melt polyurethane layer 2, a first hot melt polyurethane layer 1, and a second hot melt polyurethane. It has a three-layer structure including a third polyurethane layer 3 interposed between the layer 2.

The first hot melt polyurethane layer, the second hot melt polyurethane layer, and the third polyurethane layer are all layers made of polyurethane having a softening temperature. The first hot melt polyurethane layer and the second hot melt polyurethane layer are adhesive layers that exhibit hot melt properties when heated. The third polyurethane layer is a polyurethane layer whose softening temperature is higher than the softening temperatures of the first hot melt polyurethane layer and the second hot melt adhesive layer, and preferably not melted by heating during bonding. is there.

In the hot melt adhesive film 10, the third polyurethane layer 3 that is difficult to melt is disposed between the first hot melt polyurethane layer 1 and the second hot melt polyurethane layer 2 that contribute to adhesion. By adopting such a layer structure, referring to FIG. 2, for example, the fiber base material 11 having a low fiber density such as a mesh knitted fabric and a low apparent density has a high fiber density such as artificial leather and an apparent appearance. When the fiber substrate 12 having a high density is bonded with the hot melt polyurethane adhesive film 10 through a thermocompression bonding process by hot pressing, the third polyurethane layer 3 becomes the first hot melt polyurethane layer 1 and the second hot melt polyurethane. It becomes a barrier layer that suppresses mixing with the layer 2, and the first hot melt polyurethane layer 1 is infiltrated into the fiber base material 11, and the second hot melt polyurethane layer 2 is infiltrated into the fiber base material 12. Can do. As a result, hot melt polyurethane does not penetrate evenly into fiber substrate 11 with a low apparent density such as mesh knitted fabric, and hot melt polyurethane sufficiently penetrates into fiber substrate 12 with a high apparent density such as artificial leather. Can be made.

The softening temperature of the third polyurethane layer is higher than the softening temperature of the first hot melt polyurethane layer by 20 ° C. or more in the thermocompression bonding step using a general hot melt adhesive film. This is preferable because the barrier effect is sufficiently exhibited and the first hot-melt polyurethane layer can sufficiently penetrate into the adherend substrate facing it. The softening temperature of the third polyurethane layer is 20 ° C. higher than the softening temperatures of the first hot melt polyurethane layer and the second hot melt polyurethane layer. In the thermocompression bonding process, the first hot melt polyurethane layer can be sufficiently penetrated into the adherend substrate facing it, and the second hot melt polyurethane layer can be sufficiently penetrated into the adherend substrate facing it. It is preferable from the point.

Further, the softening temperature of the first hot melt polyurethane layer and the softening temperature of the second hot melt polyurethane layer may be the same temperature or different temperatures, and are to be adhered to each hot melt polyurethane layer. A preferable softening temperature is appropriately selected depending on the type of the substrate. For example, as shown in FIG. 2, the first hot melt polyurethane layer 1 faces the fiber substrate 11 having a low apparent density, and the second hot melt polyurethane layer 2 faces the fiber substrate 12 having the high apparent density. In this case, the softening temperature of the first hot melt polyurethane layer 1 facing the fiber substrate 11 having a low apparent density is increased, and the second hot melt polyurethane layer 2 facing the fiber substrate 12 having a high apparent density is increased. Lowering the softening temperature is preferable because each hot-melt polyurethane layer can penetrate into each fiber substrate in a well-balanced manner. In such a case, the softening temperature of the first hot melt polyurethane layer 1 is preferably 5 ° C. or more, more preferably 10 ° C. or more higher than the softening temperature of the second hot melt polyurethane layer 2.

The softening temperatures of the first hot-melt polyurethane layer and the second hot-melt polyurethane layer that function as an adhesive layer are about 100 to 140 ° C., more preferably about 110 to 135 ° C. It is preferable from the viewpoint that sufficient adhesive strength can be imparted to the laminated structure obtained by quickly melting or softening and bonding the substrates to be bonded to each other depending on the bonding conditions using the adhesive film.

The softening temperature of the third polyurethane layer functioning as a barrier layer is 145 to 195 ° C., more preferably 150 to 160 ° C., depending on the bonding conditions using a general hot melt polyurethane adhesive film. It is preferable because it does not melt and softens moderately. When the softening temperature of the third polyurethane layer is too high, it tends to be hard and the texture is lowered.

The third polyurethane layer has a thickness of 10 to 110 μm, more preferably 20 to 70 μm, and is a laminate obtained by maintaining sufficient strength during hot pressing and bonding substrates to be bonded together. This is preferable because the texture of the structure is not cured.

The thicknesses of the first hot-melt polyurethane layer and the second hot-melt polyurethane layer are appropriately selected depending on the type of the adherend substrate to be bonded, and are, for example, 20 to 300 μm, more preferably 30 to 250 μm. It is preferable from the point that sufficient adhesive strength can be maintained.

The third polyurethane layer has a 100% modulus at 25 ° C. of 2 to 7 MPa, more preferably 2.5 to 5.5 MPa, and particularly 3.0 to 4.5 MPa. It is preferable from the viewpoint that the texture of the laminated structure obtained by curing is not cured. If the 100% modulus at 25 ° C. of the third polyurethane layer is too low, the third polyurethane layer becomes weak and easily peeled off by the third polyurethane layer, resulting in insufficient adhesive strength. When the 100% modulus is too high, the third polyurethane layer becomes hard and the texture of the resulting laminated structure tends to harden.

The 100% modulus at 25 ° C. of the first polyurethane layer and the second polyurethane layer is 2 to 7 MPa, more preferably 2.5 to 5.5 MPa, particularly 3.0 to 4.5 MPa. It is preferable from the viewpoint that the texture of the laminated structure obtained by bonding the adherend substrates together is not cured.

Further, the storage elastic modulus E ′ at 140 ° C. of the third polyurethane layer is 2 to 30 MPa, more preferably 2 to 5 MPa, and it is difficult to break during hot pressing, and the first hot melt polyurethane layer This is preferable from the viewpoint of exhibiting a sufficient barrier effect so as not to mix with the second hot melt polyurethane layer. Further, it is preferable that the storage elastic modulus E ′ at 140 ° C. of the first polyurethane layer and the second polyurethane layer cannot be measured because it is melted at 140 ° C.

The hot melt polyurethane adhesive film of the first embodiment described above has a three-layer structure including a first hot melt polyurethane layer, a second hot melt adhesive layer, and a third polyurethane layer. As long as the effects of the present invention are not impaired, other layers may be further included in the inner layer as necessary.

[Second Embodiment]
The hot melt polyurethane adhesive film of 2nd Embodiment is demonstrated with reference to drawings. FIG. 3 is a schematic cross-sectional view of the hot melt polyurethane adhesive film 30 of the second embodiment. As shown in FIG. 3, the hot melt polyurethane adhesive film 30 has a two-layer structure including a first hot melt polyurethane layer 21 and a second hot melt polyurethane layer 22.

The hot-melt polyurethane adhesive film 30 of the second embodiment does not include the third polyurethane layer as compared with the hot-melt polyurethane adhesive film 10 of the first embodiment, and the first hot-melt polyurethane layer Is different in that it must be higher than the softening temperature of the second hot-melt polyurethane layer. By adopting such a layer structure, for example, a fiber base material having a low fiber density, such as a mesh knitted fabric, and a low apparent density, and a fiber base material having a high fiber density, such as artificial leather, having a high apparent density are hot. When the melt adhesive film 30 is bonded through a heat bonding process by hot pressing, the first hot-melt polyurethane layer, which has a high softening temperature and is difficult to melt, is faced to a fiber substrate having a low apparent density, and the softening temperature is high. By making the second hot-melt polyurethane layer easy to be made to face the fiber substrate having an apparent density, each hot-melt polyurethane layer can penetrate into each fiber substrate in a well-balanced manner.

In the hot melt polyurethane adhesive film of the second embodiment, the softening temperature of the first hot melt polyurethane layer may be 5 ° C. or more, more preferably 10 ° C. or more higher than the softening temperature of the second hot melt polyurethane layer. The hot-melt property of each hot-melt polyurethane layer is controlled so that the first hot-melt polyurethane layer sufficiently enters the adherend substrate facing it, and the second hot-melt polyurethane layer faces the adherend group It is preferable from the viewpoint that it can sufficiently penetrate into the material.

The softening temperature of the first hot melt polyurethane layer is 115 to 140 ° C., more preferably about 120 to 135 ° C., and the softening temperature of the second hot melt polyurethane layer is 100 to 130 ° C., further 105 to The temperature of about 125 ° C. can be quickly melted or softened according to the bonding conditions using a general hot melt polyurethane adhesive film, and the hot melt property of each hot melt polyurethane layer is controlled, so that the first hot melt The polyurethane layer is preferable because it sufficiently penetrates into the adherend substrate facing it, and the second hot-melt polyurethane layer can penetrate into the adherend substrate facing it.

Also in the hot melt polyurethane adhesive film of the second embodiment, the thicknesses of the first hot melt polyurethane layer and the second hot melt polyurethane layer are appropriately selected depending on the kind of the adherend substrate to be bonded, For example, the thickness is preferably 20 to 300 μm, more preferably 30 to 250 μm, from the viewpoint that sufficient adhesive strength can be maintained.

The hot melt polyurethane adhesive film of the second embodiment described above has a two-layer structure including a first hot melt polyurethane layer and a second hot melt polyurethane layer, but the effect of the present invention is impaired. Unless necessary, other layers may be included in the inner layer as necessary.

[Specific Examples of First Hot Melt Polyurethane Layer, Second Hot Melt Polyurethane Layer, and Third Polyurethane Layer]
The polyurethane having a softening temperature for forming each layer described in the first embodiment and the second embodiment is a thermoplastic polyurethane. According to the thermoplastic polyurethane, the softening temperature and melt viscosity of each of the first hot melt polyurethane layer, the second hot melt polyurethane layer, and the third polyurethane layer can be adjusted.

The thermoplastic polyurethane can be obtained by a conventionally known polymerization method of thermoplastic polyurethane by reacting a polymer polyol, polyisocyanate, and a chain extender, such as bulk polymerization, solution polymerization, and aqueous dispersion polymerization. Among these, bulk polymerization is preferable from the viewpoint of good volumetric reaction efficiency. The bulk polymerization method is not particularly limited. For example, a urethane prepolymer is produced by reacting a high-molecular polyol and a polyisocyanate under appropriate reaction conditions (for example, reaction at 80 ° C. for 4 hours). Examples thereof include a prepolymer method in which a chain extender is added to a polymer to polymerize polyurethane, and a one-shot method in which a polymer polyol, polyisocyanate, and a chain extender are polymerized simultaneously.

The thermoplastic polyurethane is mainly composed of a bifunctional polymer polyol (polymer diol) that does not form a branched structure in order to maintain thermoplasticity, a bifunctional polyisocyanate (diisocyanate), and a chain extender. Although it is a polyurethane obtained by reacting, a trifunctional or higher functional compound may be used as a raw material as necessary as long as sufficient thermoplasticity that does not impair the effects of the present invention can be maintained.

Specific examples of the polymer polyol used for the production of the thermoplastic polyurethane include, for example, polyether polyol (polyether diol), aliphatic polyether diol such as polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetramethylene glycol, etc. Is mentioned. These may be used alone or in combination of two or more. In these, when it contains 60 mass% or more of polyether polyol in a polyol, it is preferable from the point which is excellent in hydrolysis resistance.

The number average molecular weight of the polymer polyol is preferably 500 to 5000, more preferably 600 to 4500, and particularly preferably 700 to 4000. When the number average molecular weight of the polymer polyol is too low, the flexibility tends to decrease, and when it is too high, the mechanical properties tend to decrease.

Specific examples of the polyisocyanate include aromatic diisocyanates such as phenylene diisocyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate; hexamethylene diisocyanate , Lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, aliphatic diisocyanate such as tetramethylxylylene diisocyanate, or cycloaliphatic diisocyanate; Etc.
These may be used alone or in combination of two or more.

As the chain extender, a low molecular weight compound having a molecular weight of 400 or less and having two hydrogen atoms capable of reacting with an isocyanate group in the molecule, which has been conventionally used in the production of polyurethane, can be mentioned. Specific examples of the chain extender include, for example, hydrazine, ethylenediamine, propylenediamine, xylylenediamine, isophoronediamine, piperazine and derivatives thereof, phenylenediamine, tolylenediamine, xylenediamine, adipic acid dihydrazide, isophthalic acid dihydrazide, hexamethylene. Diamine compounds such as diamine, 4,4'-diaminophenylmethane, 4,4'-dicyclohexylmethanediamine; ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexane Diol, bis (β-hydroxyethyl) terephthalate, 3-methyl-1,5-pentanediol, cyclohexanediol, xylylene glycol, 1,4-bis (β-hydroxyethoxy) benzene, neopentyl glycol, etc. Diol compounds; amino alcohols such as aminoethyl alcohol and aminopropyl alcohol; These may be used alone or in combination of two or more.

In addition to the above chain extenders, monoamino compounds such as ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, t-butylamine, cyclohexylamine are used in combination to control the molecular weight or ε-aminocapron. A carboxyl group may be introduced at the terminal by using an aminocarboxylic acid such as acid (6-aminohexanoic acid), γ-aminobutyric acid (4-aminobutanoic acid), aminocyclohexanecarboxylic acid, and aminobenzoic acid.

The reaction ratio between the polymer polyol, the chain extender and the polyisocyanate is an isocyanate index which is an equivalent ratio of the isocyanate group in the polyisocyanate to the hydroxyl group in the polyol containing the polymer polyol and the active hydrogen group of the chain extender. However, it is preferably about 0.85 to 1.1, more preferably about 0.9 to 1.0. When the isocyanate index is high, the softening temperature of the thermoplastic polyurethane tends to be high, and when the isocyanate index is low, the softening temperature is low, and the mechanical properties tend to decrease and the adhesive strength tends to decrease. .

The thermoplastic polyurethane may be an additive, if necessary, specifically, for example, a known hindered amine-based, hindered phenol-based antioxidant, benzotriazole-based, benzophenone-based, triazine-based light-proofing agent, pigment, etc. Or a coloring agent such as a dye.

As the thermoplastic polyurethane for forming the first hot-melt polyurethane layer, the second hot-melt polyurethane layer, and the third polyurethane layer, as long as those that satisfy the softening temperature relationship as described above are combined, the kind thereof is used. The monomer composition and the like are not particularly limited.

[Adhesion method]
The hot melt polyurethane adhesive film described in the first embodiment and the second embodiment is preferably used for adhering adherend substrates having different apparent densities to each other, which are bonded by the anchor effect when the adhesive is infiltrated. It is done. The kind of the adherend substrate is not particularly limited, and examples thereof include knitted fabrics such as nonwoven fabrics, woven fabrics, and mesh knitted fabrics, artificial leather, and porous resin films.

In particular, it is particularly noticeable when non-woven fabrics and woven fabrics, non-woven fabrics and knitted fabrics, artificial leather and woven fabrics, artificial leather and knitted fabrics with different apparent densities are used as adherends, and such fiber substrates are bonded together. An effect is produced. In addition, artificial leather is a fiber base material formed by impregnating an elastic polymer such as polyurethane to a fiber base material such as a nonwoven fabric. More specifically, two fiber base materials in which the apparent density of one fiber base material is 1.3 times or more, more preferably 1.5 times or more the other fiber base material are bonded together. In this case, it is preferably used.

Bonding includes a method in which a stacked body in which a hot melt polyurethane adhesive film is interposed between two substrates to be bonded is formed and bonded while being heated and pressed by a hot press or a hot roll. The surface temperature of the hot press or hot roll mold is appropriately selected depending on the softening temperatures of the first hot melt polyurethane layer, the second hot melt polyurethane layer, and the third polyurethane layer. Generally, the temperature is appropriately set in the range of 100 to 160 ° C.

With such a hot melt polyurethane adhesive film, a laminated fiber structure formed by bonding two fiber bases having different apparent densities is bonded with polyurethane, so that cushioning properties are maintained and flexibility is increased. Excellent. Therefore, it is preferably used as an upper material for shoes, particularly as an upper material for sports shoes.

The present invention will be specifically described with reference to examples. It should be noted that the scope of the present invention is not construed as being limited in any way by these examples.

First, the evaluation method of the properties of thermoplastic polyurethane will be described together below.

<Evaluation of softening temperature and storage modulus at 140 ° C.>
Using a dynamic viscoelasticity measuring device (FT Leospectra DVE-V4 manufactured by Rheology), a test piece of thermoplastic polyurethane having a width of 5 mm, a length of 30 mm, and a thickness of 250 μm is fixed between chucks with an interval of 20 mm. The dynamic viscoelastic behavior was measured under the conditions of a region of 30 to 300 ° C., a heating rate of 3 ° C./min, a strain of 5 μm / 20 mm, and a measurement frequency of 10 Hz. And in the spectrum of the obtained storage elastic modulus (E '), the temperature at the intersection of the tangent lines of the slope before and after melting in the region where E' decreases due to melting of the thermoplastic polyurethane was defined as the softening temperature. Further, the storage elastic modulus E ′ at 140 ° C. was read.

<Evaluation of 100% modulus>
Using a film having a width of 25 mm, a length of 150 mm, and a thickness of 100 μm obtained using thermoplastic polyurethane, a tensile tester (100% modulus and head speed: 100 mm / min) in accordance with JIS K7311 Tensilon Orientec Co., Ltd.) was used.

(Examples 1 to 12, Comparative Examples 1 to 4)
Films having various thicknesses shown in Table 1 were manufactured by T-die melt extrusion using thermoplastic polyurethanes TPU1 to TPU6 having softening temperatures shown in Table 1 below. Further, as shown in Table 1, as the first hot melt adhesive layer and the second hot melt adhesive layer, low density polyethylene (LDPE) having a density of 0.921 g / cm ^3, a third hot melt adhesive layer. As a result, a polyethylene laminated film in which high density polyethylene (HDPE) having a density of 0.954 g / cm ³ was laminated was produced.

The thermoplastic polyurethane films shown in Table 1 as the first hot melt polyurethane layer (L1), the second hot melt polyurethane layer (L2), and the third polyurethane layer (L3) are shown in Table 2 below. A stack of films was formed so as to have a layer structure as shown in FIG. And the hot-melt-adhesive film used by each Example and the comparative example was created by carrying out the thermocompression-bonding of the stack of films on the conditions of pressure 5kg / cm < ² > and 30 second with a flat plate heat press. In Examples 1, 3 to 6, 8 to 10 using TPU 1 and Comparative Examples 1 and 2, the surface temperature of the flat plate heat press was set to 120 ° C., and Examples 2 and 7 using TPU 2 were used. , 11, 12 and Comparative Example 3, the surface temperature was set to 140 ° C. L1 and L2 were films having a thickness of 100 μm except for Comparative Example 2 and Comparative Example 3. In Comparative Example 2 and Comparative Example 3, a film having a thickness of 200 μm was used as it was as a hot melt polyurethane adhesive film.

Then, thickness of 1.0 mm, and the napped artificial leather pieces duplex is napped apparent density 0.6 g / cm ^3, thickness of 3.0 mm, a double raschel type of apparent density 0.3 g / cm ³ Mesh A stacked body was formed between the knitted fabrics with each polyurethane hot melt adhesive film interposed therebetween. In Example 11 and Example 12, L1 of TPU2 was faced to the mesh knitted fabric, and L1 of TPU1 was faced to the napped artificial leather piece.

Then, the stack was thermocompression-bonded with a flat plate heat press machine under conditions of a pressure of 5 kg / cm ² and 60 seconds. In the flat plate heat press, in Examples 1, 3 to 6, 8 to 10 using TPU 1 and Comparative Examples 1 and 2, the surface temperature was set to 120 ° C., and Example 2 using TPU 2 was used. In 7, 11, 12 and Comparative Example 3, the surface temperature was set to 140 ° C. In Comparative Example 4, the surface temperature was set to 115 ° C. And it was made to cool at room temperature for 1 day, and the laminated fiber structure was obtained.

The adhesive strength and texture of each laminated fiber structure obtained were evaluated according to the following evaluation method. The results are shown in Table 2.

<Adhesive strength>
The adhesion strength of the laminated fiber structure was measured using a tensile tester (Tensilon Orientec Co., Ltd.). Specifically, when creating a sample for measuring adhesive strength in the same manner as in the production of a laminated fiber structure, the sample size is 30 mm wide × 150 mm long, and when the thermocompression bonding is performed, the nap-like artificial prosthesis is about 30 mm in the length direction. Paper was sandwiched between the leather piece and the double raschel type mesh knitted fabric to provide a non-adhesive portion. Thereafter, both ends in the width direction were trimmed to remove the protruding portion of the adhesive during pressing, and a test piece having a width of 25 mm × a length of 150 mm was prepared. Then, each end portion of the non-bonded portion of the test piece is sandwiched between upper and lower chucks of a tensile tester set at an initial interval of 25 mm, and a tensile test is performed at a tensile speed of 50 mm / min. A graph was obtained. Then, the portion excluding the initial peak from the obtained graph was divided into five sections, the minimum value of the peak in each section was read, and the average value of the obtained five data was defined as the adhesion strength.

<Texture evaluation>
A test piece was prepared by cutting out the laminated fiber structure into a square of 200 mm length × 200 mm width. Then, five panelists selected from those skilled in the art of artificial leather touched the test piece and judged flexibility according to the following criteria.
A: The cushioning property of the mesh knitted fabric and the texture of the artificial leather were sufficiently maintained, and the flexibility was very high.
B: The cushioning property of the mesh knitted fabric and the texture of the artificial leather were generally maintained, and there was a standard flexibility as an upper material for general sports shoes.
C: Although there was a feeling of resilience like a resin, the texture was acceptable to some extent as an upper material for general sports shoes.
D: Wrinkles that were rounded when folded were present, and there was a strong resilience like resin, and the flexibility was poor.

As shown in Table 1, the first hot-melt polyurethane layer, the second hot-melt polyurethane layer, and the third polyurethane interposed between the first hot-melt polyurethane layer and the second hot-melt polyurethane layer Layered fiber structures of Examples 1 to 11 bonded using a hot-melt polyurethane adhesive film in which the softening temperature of the third polyurethane layer is higher than the softening temperature of the other adhesive layers. The adhesive strength was higher than that of the laminated fiber structures of Comparative Examples 1 to 3, which were bonded using a hot-melt polyurethane adhesive film having only the first hot-melt polyurethane layer. A first hot-melt polyurethane layer and a second hot-melt polyurethane layer, wherein the first hot-melt polyurethane layer is a hot-melt polyurethane adhesive film having a higher softening temperature than the second hot-melt polyurethane layer; The laminated fiber structure of Example 12 adhered using the adhesive also had higher adhesive strength than the laminated fiber structures of Comparative Examples 1 to 3. Moreover, as shown in Comparative Example 4, when an adhesive film made of a polyethylene layer was used, a laminated fiber structure inferior in adhesive strength and texture was obtained.

1,21 1st hot tomelt polyurethane layer 2,22 2nd hot tomelt polyurethane layer 3

3rd polyurethane layer

10,30 hot to melt polyurethane adhesive film 11 low apparent density fiber substrate 12 apparent density High fiber substrate

Claims

A first hot melt polyurethane layer, a second hot melt polyurethane layer, and a third polyurethane layer interposed between the first hot melt polyurethane layer and the second hot melt polyurethane layer,
A hot melt polyurethane adhesive film in which a softening temperature of the third polyurethane layer is higher than softening temperatures of the first hot melt polyurethane layer and the second hot melt polyurethane layer.
The hot melt polyurethane adhesive film according to claim 1, wherein the softening temperature of the third polyurethane layer is 20 ° C or higher than the softening temperature of the first hot melt polyurethane layer.
The hot melt polyurethane adhesive according to claim 2, wherein the softening temperature of the third polyurethane layer is 20 ° C or higher than the softening temperature of the first hot melt polyurethane layer and the softening temperature of the second hot melt polyurethane layer. Agent film.
The hot melt polyurethane adhesive film according to any one of claims 1 to 3, wherein the softening temperature of the first hot melt polyurethane layer is 5 ° C or higher than the softening temperature of the second hot melt polyurethane layer.
The softening temperature of the third polyurethane layer is 145 to 195 ° C, and the softening temperatures of the first hot melt polyurethane layer and the second hot melt polyurethane layer are 100 to 140 ° C. The hot melt polyurethane adhesive film according to any one of the above.
6. The hot melt polyurethane adhesive film according to claim 1, wherein the thickness of the third polyurethane layer is 10 to 110 μm.
The hot melt polyurethane adhesive film according to any one of claims 1 to 6, wherein a 100% modulus at 25 ° C of the third polyurethane layer is 2 to 7 MPa.
The hot melt polyurethane adhesive film according to any one of claims 1 to 7, wherein the storage elastic modulus E 'at 140 ° C of the third polyurethane layer is 2 to 30 MPa.
A first hot melt polyurethane layer and a second hot melt polyurethane layer;
A hot melt polyurethane adhesive film in which the first hot melt polyurethane layer is higher than a softening temperature of the second hot melt polyurethane layer.
A laminated fiber structure obtained by bonding two fiber base materials having different apparent densities to each other with the hot melt polyurethane adhesive film according to any one of claims 1 to 9.
The laminated fiber structure according to claim 10, wherein an apparent density of one of the two fiber substrates is 1.5 times or more of an apparent density of the other fiber substrate.
The laminated fiber structure according to claim 10 or 11, which is a shoe upper material in which one of the two fiber substrates is a knitted fabric and the other is an artificial leather.