JP7209883B1 - Moisture-curable urethane hot-melt resin composition, laminate, and synthetic leather - Google Patents

Abstract

A moisture-curable urethane hot-melt resin composition capable of forming a cured product layer having excellent initial adhesiveness, heat resistance, hydrolysis resistance, alcohol resistance and abrasion resistance is provided. A moisture-curable urethane hot-melt resin composition containing a urethane prepolymer having an isocyanate group, which is a reaction product of a polyol component and a polyisocyanate component. The polyol component includes a high molecular weight polyol component and a low molecular weight polyol component. The polymer polyol component includes SA polyester polyol (A1); 1,4-BD/AA polyester polyol (A2) having a number average molecular weight (Mn) of 8,000 or more; At least one polyol (A) selected from the group consisting of 6-HD/AA-based polyester polyol (A3); polyester polyol (B1) other than polyol (A); and polyether polyol (B2); and at least one polyol (B) selected from the group. The low-molecular-weight polyol component contains a trifunctional polyol (D) having a molecular weight of 300 or less and having three hydroxyl groups in one molecule. The ratio of polyol (A) and trifunctional polyol (D) satisfies trifunctional polyol (D) (mmol)/polyol (A) (g)=0.14 to 55 mmol/g. [Selection figure] None

Description

TECHNICAL FIELD The present invention relates to a moisture-curable urethane hot-melt resin composition, a laminate, and a synthetic imitation leather.

A moisture-curable urethane hot-melt resin composition is a composition that is solid at room temperature and can be prepared without a solvent, and is a resin composition that is heated, melted, applied, and then cured by moisture. For this reason, moisture-curable urethane hot-melt resin compositions are widely used as various environmentally friendly adhesives because they do not use solvents. Such a moisture-curable urethane hot-melt resin composition has functional groups such as isocyanate groups (NCO groups) that can react with water (humidity) present in the air or in the substrate to be coated to form a crosslinked structure. in the molecule contains a urethane prepolymer.

Moisture-curable urethane hot-melt resin compositions, when used as various adhesives, exhibit adhesive strength through moisture curing, and it is difficult to exhibit excellent initial strength. Techniques for expressing are proposed. For example, Patent Document 1 describes a "urethane prepolymer (1)" derived from an organic polyisocyanate compound (a) and a predetermined polyol (b1) and having an NCO group, and A reactive hot melt adhesive is disclosed containing a "low molecular weight xylene resin (d1)" having

JP-A-5-065471

The urethane prepolymer used in the moisture-curable urethane resin composition is also used as an adhesive for producing synthetic leather such as artificial leather and synthetic leather. Synthetic imitation leather is used as a material for manufacturing various products such as shoes, clothing, bags, furniture, and vehicle interior materials (for example, instrument panels, doors, consoles, seats). Conventional synthetic imitation leather is generally a laminate in which a skin layer, an adhesive layer (cured material layer), and a base material layer are laminated in this order, and the cured material layer is formed by various urethane prepolymers. there is The cured product layer that constitutes the synthetic imitation leather used in the above-mentioned various products is required to have good flexibility and heat resistance to withstand the heat during manufacturing and processing.

The reactive hot-melt adhesive disclosed in the above-mentioned Patent Document 1 has a certain effect on the initial adhesive strength after curing under a predetermined humidity environment. However, such a conventional moisture-curable urethane hot-melt resin composition has a low thermal softening point after curing and a less network structure after curing than a two-component curing polyurethane resin composition. Therefore, there is a limit to its application to applications that require heat resistance and processing at high temperatures, such as the synthetic imitation leather described above. In addition, when conventional moisture-curable urethane hot-melt resin compositions are used for clothing, in addition to insufficient hydrolysis resistance to withstand washing, wear resistance is insufficient and rubbing Such friction may cause separation from the base material. In addition, in the recent corona disaster, resistance to alcohol disinfection is also required.

Therefore, the present invention provides a moisture-curable urethane hot-melt resin composition capable of forming a cured product layer having good initial adhesiveness, heat resistance, flexibility, hydrolysis resistance, alcohol resistance, and abrasion resistance. is intended to provide

The present invention contains a urethane prepolymer having an isocyanate group, which is a reaction product of a polyol component and a polyisocyanate component, the polyol component includes a high molecular polyol component and a low molecular weight polyol component, and the high molecular polyol component is a polyester polyol (A1) having structural units derived from sebacic acid; a polyester polyol having a structural unit derived from 1,4-butanediol and a structural unit derived from adipic acid and having a number average molecular weight of 8,000 or more ( A2); and a polyester polyol (A3) having a structural unit derived from 1,6-hexanediol and a structural unit derived from adipic acid and having a number average molecular weight of 6,000 or more; at least one selected from the group consisting of and at least one polyol (B) selected from the group consisting of a polyol (A) and a polyester polyol (B1) other than the polyol (A); and a polyether polyol (B2); and the low-molecular-weight polyol The component contains a trifunctional polyol (D) having a molecular weight of 300 or less having three hydroxyl groups in one molecule, and the ratio of the polyol (A) and the trifunctional polyol (D) is the trifunctional polyol (D) ( mmol)/polyol (A) (g) = 0.14 to 55 mmol/g.

According to the present invention, a moisture-curable urethane hot-melt resin composition capable of forming a cured product layer having good initial adhesiveness, heat resistance, flexibility, hydrolysis resistance, alcohol resistance, and abrasion resistance. can provide things.

FIG. 4 is a schematic explanatory diagram illustrating the form of a sample used in evaluation of Examples. It is an explanatory view explaining the form of the gear oven used in the evaluation of the example.

Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments.

<Moisture-curable urethane hot-melt resin composition>
The moisture-curable urethane hot-melt resin composition of one embodiment of the present invention (hereinafter sometimes simply referred to as "resin composition") is a urethane prepolymer that is a reaction product of a polyol component and a polyisocyanate component. contains This urethane prepolymer has isocyanate groups. Due to the isocyanate group, the urethane prepolymer can react with water (humidity) present in the air or in the substrate to which the resin composition is applied to form a crosslinked structure. The resin composition used has moisture-curing properties.

Polyol components used in urethane prepolymers include high-molecular-weight polyol components and low-molecular-weight polyol components. The polymeric polyol component includes polyol (A) and polyol (B) described below. Polyol (A) is a polyester polyol (A1) having a structural unit derived from sebacic acid; a number average molecular weight having a structural unit derived from 1,4-butanediol and a structural unit derived from adipic acid is 8,000 or more. polyester polyol (A2); and polyester polyol (A3) having a number average molecular weight of 6,000 or more having structural units derived from 1,6-hexanediol and structural units derived from adipic acid; At least one. Polyol (B) is at least one selected from the group consisting of polyester polyol (B1) other than polyol (A); and polyether polyol (B2). Also, the low-molecular-weight polyol component contains a trifunctional polyol (D) having a molecular weight of 300 or less and having three hydroxyl groups in one molecule. In this resin composition, the ratio of polyol (A) and trifunctional polyol (D) satisfies trifunctional polyol (D) (mmol)/polyol (A) (g) = 0.14 to 55 mmol/g. .

With the above configuration, the moisture-curable urethane hot-melt resin composition of the present embodiment forms a cured product layer having good initial adhesiveness, heat resistance, flexibility, hydrolysis resistance, alcohol resistance, and abrasion resistance. It is possible to In one aspect, this resin composition has good stability over time in a molten state. Furthermore, in one aspect, this resin composition can contribute to the provision of synthetic imitation leather having good cold bending resistance, hydrolysis resistance, flexibility, abrasion resistance, and heat resistance.

From the viewpoint of easily obtaining the above-described effects, etc., the preferred configuration of the resin composition of the present embodiment will be described in detail below. In the following description of the compounds (each polyol component, polyisocyanate component, etc.), one or more of the compounds can be used unless otherwise specified.

[Urethane prepolymer]
A urethane prepolymer is a reaction product of a polyol component and a polyisocyanate component and has an isocyanate group. The urethane prepolymer is preferably obtained by polyaddition reaction of a polyol component and a polyisocyanate component, more preferably obtained by polyaddition of a polyol component and an excess polyisocyanate component, and has an isocyanate group at the end. Urethane prepolymer.

The equivalent ratio (molar ratio: NCO group/OH group) of the isocyanate group (NCO group) of the polyisocyanate component to the hydroxyl group (OH group) of the polyol component, which constitutes the urethane prepolymer, is 1.1 to 2.2. is preferred, 1.4 to 2.0 is more preferred, and 1.5 to 1.9 is even more preferred. By setting the NCO group/OH group within the above range, it is possible to improve workability at high temperature when used for clothing, and to produce synthetic imitation leather with better texture.

The urethane prepolymer is preferably the main component of the resin composition from the viewpoint of allowing the resin composition to exhibit moisture curability. The content of the urethane prepolymer may be 100% by mass, preferably 50% by mass or more, more preferably 70% by mass or more, and 90% by mass, based on the mass of the solid content of the resin composition. It is more preferable that it is above.

[Polyol component]
Polyol components used in urethane prepolymers include high-molecular-weight polyol components and low-molecular-weight polyol components. The high-molecular-weight polyol component is a group of polyols having a higher molecular weight than the low-molecular-weight polyol component, and preferably polymers are used. The low-molecular-weight polyol component is a group of polyols having a lower molecular weight than the high-molecular-weight polyol component.

(Polymer polyol component)
The polymer polyol component used in the urethane prepolymer includes polyol (A) described below and polyol (B) other than polyol (A). In the polyol component, the high-molecular-weight polyol component is preferably the main component of the polyol component, and is preferably used in an amount larger than that of the low-molecular-weight polyol component. The ratio of the high-molecular-weight polyol component in the polyol component is preferably 60 to 99.8% by mass, more preferably 80 to 99.5% by mass, more preferably 90 to 99% by mass, based on the total amount of the polyol component. % by mass is more preferred.

(Polyol (A))
Polyol (A) is at least one selected from the group consisting of the following polyester polyols (A1) to (A3).
(A1): Polyester polyol (A1) having structural units derived from sebacic acid
(A2): Polyester polyol (A2) having a number average molecular weight of 8,000 or more, having structural units derived from 1,4-butanediol and structural units derived from adipic acid
(A3): Polyester polyol (A3) having a number average molecular weight of 6,000 or more, having structural units derived from 1,6-hexanediol and structural units derived from adipic acid

The above polyester polyols (A1) to (A3) are polyols having crystallinity and can take a solid state at 60°C. By using the polyol (A), the resin composition can form a cured product layer having good initial adhesiveness and flexibility, and furthermore has better cold bending resistance, flexibility, and heat resistance. It becomes easier to obtain a good synthetic imitation leather. From these points of view, it is preferable to use at least the polyester polyol (A1) among the polyols (A).

Polyester polyol (A1) has structural units derived from sebacic acid (SA). Hereinafter, the polyester polyol having structural units derived from sebacic acid may be referred to as "SA-based polyester polyol". The SA-based polyester polyol (A1) is a reaction product of sebacic acid and diols, and is a bifunctional (2 hydroxyl groups) polyol (diol). SA-based polyester polyol (A1) obtained by polycondensation of sebacic acid and diols is preferred.

Diols used in the SA-based polyester polyol (A1) include, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, hexylene glycol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 1,9 - nonanediol, neopentyl glycol, and the like. Among these, 1,6-hexanediol is preferred. That is, the polyester polyol (A1) is a polyester polyol having a structural unit derived from sebacic acid and a structural unit derived from 1,6-hexanediol (hereinafter referred to as "1,6-HD/SA polyester polyol". ) is preferred.

The number average molecular weight (Mn) of the SA-based polyester polyol (A1) is preferably 2,000 or more, more preferably 3,000 or more, even more preferably 5,000 or more, and It is preferably 20,000 or less. "Number average molecular weight (Mn)" in the present specification is a value in terms of standard polystyrene measured by gel permeation chromatography (GPC). Specifically, it is measured by GPC analysis under the following conditions using dimethylformamide (DMF) as a mobile phase (the same applies to the following examples).
・Measurement device: High-speed GPC device (trade name “HLC-8220GPC”, manufactured by Tosoh Corporation)
・Column: TSK gel Super HM-N x 2,
TSK guardcolumn Super H-H x 1 ・Detector: RI (differential refractometer)
・Column temperature: 40°C
・Flow rate: 0.5 mL/min ・Injection volume: 50 μL

The polyester polyol (A2) has structural units derived from 1,4-butanediol and structural units derived from adipic acid. Hereinafter, a polyester polyol having a structural unit derived from 1,4-butanediol and a structural unit derived from adipic acid may be referred to as "1,4-BD/AA polyester polyol". The 1,4-BD/AA polyester polyol (A2) is a reaction product of 1,4-butanediol and adipic acid, and is a bifunctional (2 hydroxyl groups) polyol (diol). Polyester polyol (A2) obtained by polycondensation of 1,4-butanediol and adipic acid is preferred.

The number average molecular weight (Mn) of the 1,4-BD/AA polyester polyol (A2) is 8,000 or more. By using a 1,4-BD/AA-based polyester polyol (A2) having an Mn of 8,000 or more, the resin composition can form a cured product layer having good initial adhesiveness, and also has cold resistance. It becomes easier to obtain a synthetic imitation leather with even better flexibility and flexibility. The Mn of the 1,4-BD/AA polyester polyol (A2) is preferably 20,000 or less.

The polyester polyol (A3) has structural units derived from 1,6-hexanediol and structural units derived from adipic acid. Hereinafter, a polyester polyol having structural units derived from 1,6-hexanediol and structural units derived from adipic acid may be referred to as "1,6-HD/AA polyester polyol". The 1,6-HD/AA polyester polyol (A3) is a reaction product of 1,6-hexanediol and adipic acid, and is a bifunctional (2 hydroxyl groups) polyol (diol). Polyester polyol (A3) obtained by polycondensation of 1,6-hexanediol and adipic acid is preferred.

The number average molecular weight (Mn) of the 1,6-HD/AA polyester polyol (A3) is 6,000 or more. By using a 1,6-HD/AA-based polyester polyol (A3) having an Mn of 6,000 or more, the resin composition can form a cured product layer having good initial adhesiveness, and is resistant to cold. It becomes easier to obtain a synthetic imitation leather with even better flexibility and flexibility. The Mn of the 1,6-HD/AA polyester polyol (A3) is preferably 20,000 or less.

From the viewpoint that the above effects of polyol (A) are likely to be exhibited in a well-balanced manner with the effects of other polyols described later, the proportion of polyol (A) in the polymer polyol component is 0 based on the total amount of the polymer polyol component. It is preferably 5 to 30% by mass, more preferably 1 to 20% by mass, even more preferably 2 to 15% by mass.

(Polyol (B))
The polyol (B) is at least one selected from the group consisting of a polyester polyol (B1) other than the above polyol (A); and a polyether polyol (B2).

Polyester polyol (B1) and polyether polyol (B2) other than polyol (A) are polyols with lower crystallinity than polyol (A), and can be liquid at 60°C. By using at least one of the polyester polyol (B1) and the polyether polyol (B2), the resin composition can form a cured product layer having good flexibility, and also has cold flex resistance and It becomes easy to obtain a synthetic imitation leather having good flexibility and the like.

The polyester polyol (B1) includes the above SA polyester polyol (A1), a 1,4-BD/AA polyester polyol (A2) having an Mn of 8,000 or more, and a 1,6- A polyester polyol other than the HD/AA polyester polyol (A3). The polyester polyol (B1) is a reaction product of dicarboxylic acids and diols, and is a bifunctional (2 hydroxyl groups) polyol (diol). Polyester polyol (B1) obtained by polycondensation of dicarboxylic acids and diols is preferred.

Dicarboxylic acids used in the polyester polyol (B1) include, for example, aliphatic dicarboxylic acids such as succinic acid, adipic acid, glutaric acid, and azelaic acid; and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid. ; can be mentioned. Examples of the diols used in the polyester polyol (B1) include the same diols as those described in the explanation of the SA-based polyester polyol (A1).

Specific examples of the polyester polyol (B1) include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyneopentyl adipate diol, polyethylene/butylene adipate diol, polyneopentyl/hexyl adipate diol, poly-3- Examples include methylpentane adipate diol and polybutylene isophthalate diol.

Among the polyester polyols (B1), 1,4 having a structural unit derived from 1,4-butanediol and a structural unit derived from adipic acid and having a number average molecular weight (Mn) of 1,000 to 5,000 -BD/AA polyester polyol (B1) is preferred. Among them, polybutylene adipate diol with Mn of 1,200 to 4,000 is more preferable, and polybutylene adipate diol with Mn of 1,500 to 3,000 is more preferable.

The polyether polyol (B2) is a bifunctional (2 hydroxyl groups) polyol (diol). Polyether polyol (B2) is obtained by polymerizing or copolymerizing, for example, alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) and heterocyclic ether (tetrahydrofuran, 2-methyltetrahydrofuran, etc.). be done. The polyether polyol (B2) can also be obtained by a dehydration condensation reaction of a diol such as 1,3-propanediol.

Examples of the polyether polyol (B2) include polyethylene glycol, polypropylene glycol, polyethylene glycol-polytetramethylene glycol (block or random), polytrimethylene ether glycol, polytetramethylene ether glycol, and polyhexamethylene ether glycol. can be mentioned. Among them, polyethylene glycol, polytrimethylene ether glycol, and polytetramethylene ether glycol are preferable from the viewpoint of flexibility.

In one aspect of the moisture-curable urethane hot-melt resin composition, from the viewpoint of making the composition more environmentally friendly, the polyol (B) (the above polyester polyol (B1) and/or polyether polyol (B2)) is It preferably contains a polyol (B _b ) using a plant-derived raw material. A polyol (B _b ) using a plant-derived raw material may be referred to as a biomass polyol (B _b ). The polyol (B _b ) using a plant-derived raw material includes, for example, a polyester polyol in which one or more kinds of plant-derived diols (preferably diols having 2 to 4 carbon atoms) are used as raw materials. Examples include (B _b 1) and polyether polyol (B _b 2), and polyether polyol (B _b 2) using plant-derived tetrahydrofuran or the like. Plant-derived diols having 2 to 4 carbon atoms include, for example, plant-derived ethylene glycol, 1,2-propanediol, 1,3-propanediol, and 1,4-butanediol.

From the viewpoint that the above effects of polyol (B) are likely to be exhibited in a well-balanced manner with the effects of other polyols, the proportion of polyol (B) in the high-molecular-weight polyol component is 10 to 98, based on the total amount of the high-molecular-weight polyol component. % by mass is preferable, 50 to 95% by mass is more preferable, and 60 to 90% by mass is even more preferable.

(Polycarbonate polyol (C))
The polymer polyol component preferably contains polycarbonate polyol (C) in addition to the polyol (A) and polyol (B) described above. By using the polycarbonate polyol (C), it becomes easier to obtain a cured product layer and a synthetic imitation leather having even better hydrolysis resistance and abrasion resistance.

Polycarbonate polyol (C) can be obtained, for example, by condensing diols such as 1,4-butanediol and 1,6-hexanediol with dialkyl carbonate while undergoing a dealcoholization reaction. The polycarbonate polyol (C) is a bifunctional (having two hydroxyl groups) polyol (diol), and may be either crystalline or amorphous.

Polycarbonate polyols (C) include, for example, polytetramethylene carbonate diol, polypentamethylene carbonate diol, polyneopentyl carbonate diol, polyhexamethylene carbonate diol, poly(1,4-cyclohexanedimethylene carbonate) diol, and these Random/block copolymers and the like can be mentioned. Among these are polyhexamethylene carbonate diols (polycarbonate diols based on 1,6-hexanediol), poly(tetramethylene/decamethylene) carbonate diols (polycarbonate diols based on 1,4-butanediol and 1,10-decanediol). ), and poly(pentamethylene/hexamethylene) carbonate diols (carbonate diols based on 1,5-pentanediol and 1,6-hexanediol).

In one aspect of the moisture-curable urethane hot-melt resin composition, the polycarbonate polyol (C) preferably contains a polycarbonate polyol (C _b ) using a plant-derived raw material from the viewpoint of making the composition more environmentally friendly. . A polycarbonate polyol (C _b ) using a plant-derived raw material may be referred to as a biomass polycarbonate polyol (C _b ). Polycarbonate polyols (C _b ) using plant-derived raw materials include, for example, polycarbonate polyols in which one or more of plant-derived diols (preferably diols having 2 to 10 carbon atoms) are used as raw materials. (C _b ) and the like can be mentioned. Plant-derived diols include, for example, plant-derived ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 1,10-decanediol.

From the viewpoint that the effects of the polycarbonate polyol (C) and the effects of the polyols (A) and (B) are easily exhibited in a well-balanced manner, the proportion of the polycarbonate polyol (C) in the polymer polyol component is set to the total amount of the polymer polyol component. is preferably from 0 to 80% by mass, more preferably from 4 to 40% by mass, and even more preferably from 8 to 30% by mass.

When the polymer polyol component contains polycarbonate polyol (C), the total amount of polyol (B) and polycarbonate polyol (C) is , is preferably greater than the amount of polyol (A). Furthermore, in this case, the ratio of the total (total mass) of the polyol (A), the polyol (B), and the polycarbonate polyol (C) to the total amount (total mass) of the polyol components is preferably 90% by mass or more. . The sum of polyol (A), polyol (B), and polycarbonate polyol (C) may be the total amount of polymeric polyol components. Therefore, as described above regarding the ratio of the polymer polyol component in the polyol component, the total ratio of the polyol (A), the polyol (B), and the polycarbonate polyol (C) to the total amount of the polyol component is 99.8% by mass. or less, more preferably 99.5% by mass or less, and even more preferably 99% by mass or less.

(Low-molecular-weight polyol component)
The low-molecular-weight polyol component used in the urethane prepolymer is preferably used in an amount smaller than that of the above-mentioned high-molecular-weight polyol component in the polyol component. The ratio of the low-molecular weight polyol component in the polyol component is preferably 0.2 to 40% by mass, more preferably 0.5 to 20% by mass, more preferably 1 to 10% by mass, based on the total amount of the polyol component. % by mass is more preferred.

(Trifunctional polyol (D))
The low-molecular-weight polyol component used in the urethane prepolymer contains a trifunctional polyol (D) having a molecular weight (chemical formula weight) of 300 or less and having three hydroxyl groups in one molecule. The low-molecular-weight polyol component may contain other low-molecular-weight polyols (E) in addition to the trifunctional polyol (D), if necessary.

Since the trifunctional polyol (D) has three hydroxyl groups in one molecule, it may also be referred to as triol (D). By using this specific low-molecular trifunctional polyol (D), it is possible to obtain the moisture-curable urethane hot-melt resin composition aimed at in the present disclosure.

Examples of the trifunctional polyol (D) having a molecular weight of 300 or less include glycerin, trimethylolethane, trimethylolpropane, butanetriol, pentanetriol, hexanetriol, heptanetriol and octanetriol. Among these, glycerin and trimethylolpropane are preferred.

The amount of the trifunctional polyol (D) to be used is within the following ranges in relation to the aforementioned polyol (A). That is, the ratio of polyol (A) and trifunctional polyol (D) satisfies trifunctional polyol (D) (mmol)/polyol (A) (g)=0.14 to 55 mmol/g. The moisture-curable urethane hot-melt resin composition aimed at in the present disclosure is obtained by setting the trifunctional polyol (D) to be 0.14 mmol or more and 55 mmol or less per unit mass (1 g) of the polyol (A). can be done. From the viewpoint of easily obtaining the desired resin composition, the ratio of trifunctional polyol (D) (mmol)/polyol (A) (g) is preferably 0.3 mmol/g or more, more preferably 0.5 mmol/g or more. and more preferably 1 mmol/g or more. In addition, the ratio of trifunctional polyol (D) (mmol)/polyol (A) (g) is preferably 30 mmol/g or less, more preferably 20 mmol/g or less, and 10 mmol/g or more. More preferred.

From the viewpoint that the above-mentioned effects of the trifunctional polyol (D) are likely to be expressed, the proportion of the trifunctional polyol (D) in the low-molecular-weight polyol component is 50 to 100% by mass based on the total amount of the low-molecular-weight polyol component. preferably 70 to 100% by mass, even more preferably 90 to 100% by mass.

Other low-molecular-weight polyols (E) include, for example, low-molecular-weight diols and low-molecular-weight polyols having a functionality of 4 or more. Examples of low-molecular-weight diols include those similar to the diols described in the explanation of the SA-based polyester polyol (A1). Tetra- or higher-functional low-molecular-weight polyols include, for example, diglycerin, pentaerythritol, and dipentaerythritol.

[Polyisocyanate component]
The polyisocyanate component used in the urethane prepolymer is not particularly limited, and a compound (polyisocyanate) having two or more isocyanate groups in one molecule can be used. Examples of polyisocyanates include aromatic diisocyanates, alicyclic diisocyanates, aliphatic diisocyanates, and modified aliphatic diisocyanates. Among these, aromatic diisocyanates, alicyclic diisocyanates, and modified aliphatic diisocyanates are preferred, aromatic diisocyanates and modified aliphatic diisocyanates are more preferred, and aromatic diisocyanates are even more preferred.

Examples of aromatic diisocyanates include 4,4'-diphenylmethane diisocyanate (MDI), 2,2'-MDI, 2,4'-MDI, 2,4-tolylene diisocyanate (TDI), 2,6-TDI, m-xylylene diisocyanate (XDI), 1,4-phenylene diisocyanate, 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, 2 ,4-diisocyanate diphenyl ether, 1,5-naphthalene diisocyanate, and benzidine diisocyanate. Among these, MDI is preferred.

Alicyclic diisocyanates include, for example, 4,4′-methylenebis(cyclohexyl isocyanate), isophorone diisocyanate (IPDI), 1,3-bis(isocyanatomethyl)cyclohexane (hydrogenated XDI), dicyclohexylmethane-4,4′ -diisocyanate (hydrogenated MDI) and 1-methylcyclohexane-2,4-diisocyanate (hydrogenated TDI).

Examples of aliphatic diisocyanates include 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), and 1,10-decamethylene diisocyanate.

Examples of modified aliphatic diisocyanates include isocyanurate, allophanate, biuret, and adducts of aliphatic diisocyanates with polyols (such as trimethylolpropane). Among these, allophanate derivatives of aliphatic diisocyanates are preferred, and allophanate derivatives of HDI are more preferred.

[Method for producing urethane prepolymer]
The urethane prepolymer, for example, a polyol component and a polyisocyanate component, by a one-shot method or a multistage method, preferably at 60 to 150 ° C., more preferably 60 to 110 ° C., the theoretical NCO group content (mass% ) can be produced by reacting until If necessary, a catalyst may be used in combination during the reaction between the polyol component and the polyisocyanate component. Examples of catalysts include metal salts and organometallic derivatives such as dibutyltin laurate, dioctyltin laurate, stannous octoate, lead octylate, and tetra-n-butyl titanate; organic amines such as triethylamine; and diazabicycloundecene-based catalysts. ; etc. can be mentioned.

The polyol component and the polyisocyanate component are preferably reacted in the absence of a solvent such as an organic solvent, that is, without a solvent. A solvent-free urethane prepolymer can be obtained by reacting a polyol component and a polyisocyanate component in the absence of a solvent such as an organic solvent.

It is preferable to use various polyols so that the amount of the polyol component used when producing the urethane prepolymer is within the range of the above-mentioned proportions for the polyol component. For example, with respect to the polymer polyol component, the polyol (A) and polyol (B), and the optionally used polycarbonate polyol (C) are each contained in an amount within the above-mentioned ratio range in the polymer polyol component. It is preferred to use Moreover, the trifunctional polyol (D) used as the low-molecular-weight polyol component is preferably used in an amount within the range of the proportion of the low-molecular-weight polyol component in the polyol component described above. As a preferred example, the amount of trifunctional polyol (D) used is 0.5 to 30 parts by mass with respect to a total of 100 parts by mass of polyol (A), polyol (B), and polycarbonate polyol (C). preferably 0.5 to 20 parts by mass, even more preferably 0.5 to 10 parts by mass.

The moisture-curable urethane hot-melt resin composition may optionally contain a thermoplastic resin, a tackifying resin, a catalyst, a pigment, an antioxidant, an ultraviolet absorber, a surfactant, a flame retardant, a filler, and a blowing agent. You may mix|blend appropriate amounts of various additives, such as. However, the moisture-curable urethane hot-melt resin composition may consist essentially of the urethane prepolymer described above. Even when the resin composition consists essentially of the urethane prepolymer, the composition may contain components that may inevitably exist due to the production of the urethane prepolymer.

As described in detail above, in one aspect, the moisture-curable urethane hot-melt resin composition has good stability over time in a molten state, initial adhesion, heat resistance, alcohol resistance, flexibility, and resistance to heat. It is possible to form a cured product layer with good hydrolyzability and wear resistance. Therefore, this resin composition is suitable for applications that require heat resistance and high-temperature processing, such as synthetic imitation leather, and applications that require washing resistance and abrasion resistance, such as for clothing. It can be used, and its workability and extension of applications can be expected.

Further, by using this moisture-curable urethane hot-melt resin composition, it is possible to provide a laminate such as a synthetic imitation leather having good cold bending resistance, hydrolysis resistance, flexibility, abrasion resistance, and heat resistance. is also possible. For example, the above resin composition can be used as a hot-melt adhesive for bonding a substrate layer such as a base fabric constituting synthetic imitation leather and a skin layer. In addition, since this resin composition can form a cured product layer having good initial adhesiveness and abrasion resistance, it maintains the performance of good adhesion to a base material layer such as a base fabric, and is resistant to wear. It is also possible to form a cured product layer having performance as a skin layer such as abrasion resistance.

<Laminate>
A laminate according to one embodiment of the present invention comprises a base material and a cured product layer of the aforementioned moisture-curable urethane hot-melt resin composition provided on the base material. When the resin composition is used as a hot-melt adhesive, the base material can be used as one adherend, and another base material can be used as the other adherend. As the substrate (adherend), in addition to the skin layer and substrate layer for synthetic imitation leather described later, optical films, optical plates, flexible printed circuit boards, glass substrates, and substrates obtained by vapor-depositing ITO on these substrates, etc. film-shaped or sheet-shaped substrates, and metallic and non-metallic (plastic, glass, etc.) substrates.

The laminate can be produced by coating a substrate with a moisture-curable urethane hot-melt resin composition that is preferably melted at 80 to 130° C. and curing it with moisture to form a cured product layer. . When the resin composition is used as a hot-melt adhesive, the melted resin composition is applied to one base material, and then the other base material is laminated thereon and cured by moisture.

The method of applying the moisture-curable urethane hot-melt resin composition to the base material is not particularly limited, and any method conventionally used for hot-melt adhesives can be used as appropriate. Coating methods include, for example, a comma coating method, a knife coating method, a roll coating method, a screen coating method, a T-die coating method, a fiber coating method, a gravure transfer coating method in which a roll is engraved, and a die coater method using a gear pump. etc.

The laminate of this embodiment can also be configured as a synthetic imitation leather, which will be described later. In addition, as described above, the cured product layer of the moisture-curable urethane hot-melt resin composition used in the laminate has good initial adhesiveness and abrasion resistance, so it can be used as a base fabric or the like constituting synthetic imitation leather. It can form a skin layer that adheres directly to the material. Therefore, it is possible to provide a synthetic imitation leather having a two-layer structure consisting of a base material such as a base fabric and a skin layer formed of the above cured material layer provided on the base material.

A synthetic imitation leather having a skin layer made of a cured product layer of a moisture-curable urethane hot-melt resin composition can be produced, for example, as follows. First, by the coating method described above, the moisture-curable urethane hot-melt resin composition that forms the skin layer is melted and coated on release paper, and a base material such as a base fabric is laminated thereon. The resin composition is cured to form a cured product layer (skin layer). Then, by peeling from the release paper, it is possible to obtain a synthetic imitation leather having a two-layer structure consisting of a base material and a skin layer made of a cured product layer provided on the base material. In addition, when bonding the base material such as the base fabric, for example, a laminator equipped with rolls or the like can be used for pressure bonding. When curing the resin composition with moisture, it can be aged under predetermined temperature and humidity conditions.

<Synthetic imitation leather>
A synthetic imitation leather according to one embodiment of the present invention comprises a base material layer, a skin layer, and an adhesive layer provided therebetween and bonding them together. In this synthetic imitation leather, the adhesive layer is formed of the cured product layer of the moisture-curable urethane hot-melt resin composition described above.

Examples of the base fabric constituting the base layer include woven fabrics made of twill weave, plain weave, etc., raised cloth obtained by mechanically raising the cotton fabric of the woven fabric, rayon cloth, nylon cloth, polyester cloth, and Kevlar cloth. , nonwoven fabrics (polyester, nylon, various latexes), various films, sheets, and the like. Moreover, as the skin layer, one formed with a skin layer-forming paint such as a solution-type urethane resin composition, water-based polyurethane, and thermoplastic polyurethane (TPU) can be mentioned.

Synthetic imitation leather can be produced, for example, as follows. First, a coating for forming a skin layer is applied onto release paper by a known method such as comma coating, knife coating, roll coating, gravure coating, die coating, or spray coating. After the applied paint is dried appropriately to form a skin layer, the moisture-curable urethane hot-melt resin composition melted on the skin layer is applied by the coating method described above, and the base fabric is applied thereon. A base material layer such as the above is pasted together and pressure-bonded with a laminator or the like. After that, it is aged under predetermined temperature and humidity conditions as necessary to form a cured product layer (adhesive layer). Then, the target synthetic imitation leather can be obtained by peeling from the release paper.

A surface treatment agent may be applied to the surface of the skin layer constituting the synthetic imitation leather (including the skin layer composed of the cured material layer described in the explanation of the laminate). By surface-treating the skin layer with a surface-treating agent, it is possible to obtain a synthetic imitation leather with a quality more suitable for commercialization. The synthetic imitation leather of this embodiment is suitable as a material for composing shoes, clothing, bags, furniture, vehicle interior materials (for example, instrument panels, doors, consoles, seats), and the like.

In addition, as described above, an embodiment of the present invention can have the following configuration.
[1] Containing a urethane prepolymer having an isocyanate group, which is a reaction product of a polyol component and a polyisocyanate component,
The polyol component includes a high-molecular-weight polyol component and a low-molecular-weight polyol component,
The polymer polyol component is
Polyester polyol (A1) having a structural unit derived from sebacic acid; Polyester polyol (A2) having a structural unit derived from 1,4-butanediol and a structural unit derived from adipic acid and having a number average molecular weight of 8,000 or more and a polyester polyol (A3) having a number average molecular weight of 6,000 or more having structural units derived from 1,6-hexanediol and structural units derived from adipic acid; at least one polyol selected from the group consisting of ( A) and
polyester polyol (B1) other than the polyol (A); and at least one polyol (B) selected from the group consisting of polyether polyol (B2);
The low-molecular-weight polyol component includes a trifunctional polyol (D) having a molecular weight of 300 or less and having three hydroxyl groups in one molecule,
Moisture-curable urethane satisfying the ratio of the polyol (A) and the trifunctional polyol (D), the trifunctional polyol (D) (mmol) / the polyol (A) (g) = 0.14 to 55 mmol/g. A hot-melt resin composition.
[2] The moisture-curable urethane hot-melt resin composition according to [1] above, wherein the polyol (B) contains a polyol (B _b ) using a plant-derived raw material.
[3] The moisture-curable urethane hot-melt resin composition according to the above [1] or [2], wherein the polymer polyol component further contains a polycarbonate polyol (C).
[4] The moisture-curable urethane hot-melt resin composition according to [3] above, wherein the polycarbonate polyol (C) contains a polycarbonate polyol (C _b ) using a plant-derived raw material.
[5] The total amount of the polyol (B) and the polycarbonate polyol (C) is greater than the amount of the polyol (A),
The humidity according to [3] or [4] above, wherein the total proportion of the polyol (A), the polyol (B), and the polycarbonate polyol (C) is 90% by mass or more with respect to the total amount of the polyol component. A curable urethane hot-melt resin composition.
[6] A laminate comprising a substrate and a cured product layer of the moisture-curable urethane hot-melt resin composition according to any one of [1] to [5] provided on the substrate.
[7] A substrate layer, a skin layer, and an adhesive layer provided therebetween and bonding them together, wherein the adhesive layer is any one of the above [1] to [5] Synthetic imitation leather which is a cured product layer of the moisture-curable urethane hot-melt resin composition according to 1.

EXAMPLES The present invention will be specifically described below based on Examples, but the present invention is not limited to these Examples.

<Materials used>
The polymeric polyol materials used are shown in Table 1 below.

<Production of moisture-curable urethane hot-melt resin composition>
(Example 1)
A glass reaction vessel equipped with a stirrer, a thermometer, and a gas inlet is charged with a polyol component and a polyisocyanate component, mixed, dehydrated by heating and decompressing the reaction vessel, and then filled with nitrogen gas. Then, the internal temperature was adjusted to 100° C., and the mixture was reacted with stirring for 120 minutes. The polyol component includes 10 parts by mass of polyester polyol (A1), 45 parts by mass of polyester polyol (B1-1), and 45 parts by mass of polyether polyol (B2-1). Polymer polyol component (total 100 parts by mass) , and 0.5 parts by mass of trimethylolpropane, which is a trifunctional polyol (D) component having a molecular weight of 300 or less. The ratio of polyol (A) and trifunctional polyol (D) was trifunctional polyol (D) (mmol)/polyol (A) (g)=0.37 mmol/g. 22.35 parts by mass of 4,4′-diphenylmethane diisocyanate (MDI) is used as the polyisocyanate component, and the molar ratio of the NCO groups of MDI to the OH groups of the polyol component (NCO group/OH group) is 1.7. and Thus, a urethane prepolymer of Example 1 was obtained.

(Examples 2 to 17 and Comparative Examples 1 to 10)
Same as Example 1 except that the type and amount of polyol component used and the amount of polyisocyanate component (MDI) used were changed as shown in the upper part of Table 2 below (Tables 2-1 to 2-6). to obtain a urethane prepolymer of each example. With the change in the amount of the polyol component and the polyisocyanate component used, in the middle row of Table 2, the value of "trifunctional polyol (D) / polyol (A) [mmol / g]" and "NCO group / OH group ( molar ratio)” is also shown. In Comparative Example 10 with trifunctional polyol (D) (mmol)/polyol (A) (g) = 56.0 mmol/g, gelation occurred during the reaction with stirring, and the evaluation described below could not be performed. rice field.

<Evaluation>
The urethane prepolymer obtained in each example is used as the moisture-curable urethane hot-melt resin composition of each example (hereinafter sometimes simply referred to as "hot-melt resin composition"). made an evaluation. In the evaluation criteria for each item, AA, A, and B are acceptable good levels, and C is an unacceptable level. Evaluation results are shown in the lower part of Table 2.

(Stability over time in molten state)
The hot-melt resin composition of each example was heated to 100° C. to melt, and under the conditions of 100° C. for 24 hours, changes in viscosity over time and sedimentation were confirmed visually. The viscosity of the hot-melt resin composition was measured using a BM type viscometer (Tokyo Keiki Seisakusho). 4, 30 rpm, and 100°C. The temporal stability of the hot-melt resin composition in a molten state was evaluated according to the following evaluation criteria based on the above change in viscosity over time and the presence or absence of sediment.
AA: Viscosity change rate is less than 20% without sediment.
A: No sediment, viscosity change rate of 20% or more and less than 50%.
B: A sediment is present, and the viscosity change rate is less than 100%.
C: A sediment is present, and the viscosity change rate is 100% or more.

(Production of film for evaluation)
The hot-melt resin composition of each example was melted at 100° C. and coated on release paper so that the film thickness after coating would be 50 to 70 μm. After that, it was aged for 72 hours under an environment of 25° C. temperature and 60% relative humidity (60% RH), and further stored at room temperature (20° C.) for 1 day to obtain an evaluation film with release liner.

(Thermal softening point)
The thermal softening point was measured using an evaluation film (width 1.5 cm, length 6 cm) obtained by peeling off the release paper from the evaluation film with the release paper. Specifically, first, as shown in FIG. 1, clips 12 are attached to the top and bottom of the evaluation film 10, and the clips 12 are further fixed with Sellotape (registered trademark). A sample 16 was prepared by attaching a weight 14 that applies a load of cm ² . In addition, 2 cm in the central longitudinal direction of the evaluation film 10 is not covered with Sellotape (registered trademark). Next, as shown in FIG. 2, the clip 12 of the sample 16 to which the weight 14 was not attached was attached to the rotating disk 22 of the gear oven 20 . After that, while rotating the rotating disk 22 at 5 rpm, the temperature inside the gear oven 20 was raised from room temperature at a rate of 3° C./min. The temperature (° C.) at which the evaluation film 10 was cut or stretched twice was taken as the thermal softening point. Based on the value of the thermal softening point (°C), heat resistance was evaluated according to the thermal softening point according to the following evaluation criteria. The higher the heat softening point, the higher the heat resistance of the film.
A: The thermal softening point is 185°C or higher.
B: The thermal softening point is 170°C or higher and lower than 185°C.
C: The thermal softening point is less than 170°C.

(Alcohol resistance)
A film for evaluation obtained by peeling off the release paper from the film for evaluation with release paper was cut into a size of 50 mm×50 mm, and immersed in ethanol at 25° C. previously placed in a Petri dish for 10 minutes. After 10 minutes, the film for evaluation was taken out from the ethanol, the state of the film for evaluation was visually confirmed, and the alcohol resistance was evaluated according to the following evaluation criteria.
AA: The linear swelling rate of one side of the film for evaluation is less than 120%.
A: The linear swelling rate of one side of the film for evaluation is 120% or more and less than 150%.
B: The linear swelling rate of one side of the film for evaluation is 150% or more.
C: The film for evaluation is dissolved.

(initial adhesiveness)
The hot melt resin composition of each example is heated to 100 ° C. to melt, and is uniformly coated on a PET film (width 3 cm) at a coating amount of 100 μm / wet to obtain a hot melt resin composition coating layer. formed. Immediately after coating, the base fabric (fabric) was pressure-bonded with a laminator set to a roll temperature of 30° C. and a lamination clearance of 70% of the total thickness of the base fabric, coating layer and PET film. Ten minutes after bonding, the adhesive strength was measured with a digital force gauge (manufactured by Nidec-Shimpo Corporation), and the initial adhesiveness was evaluated according to the following evaluation criteria. In addition, if the adhesive strength after 10 minutes of bonding is less than 0.2 kg / 3 cm, the base fabric and the resin layer formed by the hot-melt resin composition will re-peel or twist in the subsequent processing steps, and there is a risk of defects. Based on the knowledge that the adhesive strength increases, the adhesion strength of 0.2 kg/3 cm or more after 10 minutes of bonding was judged to be acceptable.
A: Adhesion strength is 0.4 kg/3 cm or more.
B: Adhesive strength is 0.2 kg/3 cm or more and less than 0.4 kg/3 cm.
C: The adhesive strength is less than 0.2 kg/3 cm.

<Production of synthetic imitation leather for evaluation>
(1) Fabrication of skin layer As described below, a skin layer in synthetic imitation leather was fabricated. First, solution-type urethane resin (trade name “Rezamin NE-8875-30M”, manufactured by Dainichiseika Kogyo Co., Ltd.) 100 parts by mass, coloring agent (trade name “Seika Seven BS-780 (S) Black”, Dainichiseika Kogyo A urethane resin composition for a skin layer was prepared by mixing 10 parts by mass of Methyl Ethyl Ketone (MEK) and 25 parts by mass of dimethylformamide (DMF) as dilution solvents. Next, the prepared urethane resin composition was uniformly coated on release paper with a bar coater at a coating amount of 250 μm/wet. Then, it was dried at 120° C. for 5 minutes to obtain a skin layer having a thickness of 30 to 50 μm formed on a release paper.

(2) Preparation of standard synthetic imitation leather for evaluating flexibility made leather. First, a solution-type urethane resin (trade name “Rezamin UD-8373BL”, manufactured by Dainichiseika Kogyo Co., Ltd.) 100 parts by mass, an isocyanate-based cross-linking agent (trade name “Rezamin NE”, manufactured by Dainichiseika Kogyo Co., Ltd.) 12 parts by mass, Then, 30 parts by mass of methyl ethyl ketone (MEK) and 30 parts by mass of dimethylformamide (DMF) were mixed as dilution solvents to prepare an adhesive. Next, the prepared adhesive is applied to the skin layer on the release paper obtained in the above "(1) Preparation of skin layer" so that the dry film thickness is about 100 μm, and the adhesive is coated. formed. After removing the solvent in the adhesive coating layer by heating, immediately remove the base fabric (fabric), roll temperature 40 ° C, laminate clearance to the base fabric, coating layer (adhesive layer), skin layer, and release paper The laminator was set to 70% of the total thickness of . After that, the coating layer was cured at 50° C. for 48 hours to form an adhesive layer, and then the release paper in contact with the skin layer was peeled off to obtain a standard synthetic imitation leather.

(3) Preparation of synthetic imitation leather of each example Using the skin layer obtained in "(1) Preparation of skin layer" and the hot-melt resin composition of each example, the synthetic imitation leather of each example is as follows. was made. First, the hot-melt resin composition is heated to 100° C. to melt, and the melted hot-melt resin composition is applied to the skin layer on the release paper obtained in the above “(1) Fabrication of the skin layer”. Coating was performed so as to have a film thickness to form a coating layer of the hot-melt resin composition. Immediately after coating, the base fabric (fabric) is rolled at a roll temperature of 30 ° C., and the laminate clearance is set to 70% of the total thickness of the base fabric, coating layer (hot melt resin composition layer), skin layer, and release paper. It was crimped with a set laminator. Then, after aging for 48 hours at 25° C. and 60% RH to form a cured product layer of the hot-melt resin composition, the release paper in contact with the skin layer was peeled off. Thus, a synthetic imitation leather was obtained in which the base fabric (fabric) as the base material layer and the skin layer were adhered via the cured hot-melt resin composition layer as the adhesive layer.

(cold-resistant flexibility)
A test sheet having a width of 50 mm and a length of 150 mm (evaluation range: 100 mm) was prepared for the synthetic imitation leather of each example. Using the prepared test sheet, a dematcha bending tester (model number "No. 119-L DEMATTIA FLEXING TESTER", manufactured by Yasuda Seiki Seisakusho Co., Ltd.) was used in a -10 ° C environment, with a stretching and bending range of 72 to 108%, at a low temperature of -10 ° C. A flex test was performed below. Then, the cold bending resistance was evaluated according to the following evaluation criteria.
AA: No cracks after 60000 cycles.
A: No cracks after 30000 times, cracks by 60000 times.
B: No cracks after 10000 times, cracks by 30000 times.
C: Cracking after 10000 times.

(hydrolysis resistance)
For the synthetic imitation leather of each example, the adhesive strength before the hydrolysis resistance test and the adhesive strength after the hydrolysis resistance test were measured, and the hydrolysis resistance was evaluated by comparing them. Specifically, a hot melt tape is crimped on the upper surface of the skin layer of the synthetic imitation leather for 1 minute with an iron at 140 ° C., cooled at room temperature (20 ° C.) for 1 hour, and then the base fabric of the synthetic imitation leather, The skin layer adhered to the hot-melt tape is peeled off in the direction of 180° at a speed of 200 mm/min, and the strength is measured with a tensile tester (model name "Autograph AGS-100A", manufactured by Shimadzu Corporation). The adhesive strength was obtained by measuring.
On the other hand, the synthetic imitation leather of each example was placed in a constant temperature bath at 70° C. and 95% RH for a predetermined period, and then the adhesive strength after the hydrolysis resistance test was measured in the same manner as above. The adhesive strength before the test and the adhesive strength after the test were compared, and hydrolysis resistance was evaluated according to the following evaluation criteria. The retention rate of the adhesive strength means the ratio of the adhesive strength after storage for a predetermined period in the tank to the adhesive strength before putting in the tank.
AA: Retention rate of adhesive strength after storage for 8 weeks is 70% or more.
A: Retention rate of adhesive strength after storage for 5 weeks is 70% or more.
B: The adhesive strength retention rate after storage for 5 weeks is 50% or more and less than 70%.
C: The adhesive strength retention after storage for 5 weeks is less than 50%.

(flexibility)
Each synthetic imitation leather and the standard synthetic imitation leather obtained in the above "(2) Preparation of standard synthetic imitation leather for flexibility evaluation" are compared by hand, and the following based on the standard synthetic imitation leather The flexibility was evaluated according to the evaluation criteria of
AA: Significantly softer than standard synthetic imitation leather.
A: Softer than standard synthetic imitation leather.
B: As soft as standard synthetic imitation leather.
C: Significantly harder than standard synthetic imitation leather.

(wear resistance)
The hot-melt resin composition of each example is heated to 100° C. to melt, and the melted hot-melt resin composition is coated on a release paper so as to have a dry film thickness of about 100 μm, and the hot-melt resin composition is applied. layer was formed. Immediately after coating, the base fabric (fabric) was set to a roll temperature of 30 ° C., and the lamination clearance was set to 70% of the total thickness of the base fabric, coating layer (hot melt resin composition layer), and release paper. It was crimped with Then, after aging for 48 hours at 25° C. and 60% RH to form a cured product layer of the hot-melt resin composition, the release paper in contact with the cured product layer was peeled off. In this way, a synthetic imitation leather comprising a base fabric (fabric) and a skin layer made of a cured product layer of a hot-melt resin composition provided on the base fabric was produced as a two-layer laminate. . This was used as a synthetic imitation leather for the abrasion resistance test described below.

A circular test piece with a diameter of 11.5 cm was prepared for the synthetic imitation leather for abrasion resistance test of each example. Using this test piece and a Taber abrasion tester (manufactured by Yasuda Seiki Seisakusho), an abrasion resistance test was conducted under the conditions of a load of 500 g, a rotation speed of 60±2 rpm, and an abrasion wheel of CS-10. Then, the wear resistance was evaluated according to the following evaluation criteria.
AA: No change in appearance such as scratches after 1500 times.
A: No change in appearance such as scratches after 1000 cycles, and change in appearance such as scratches by 1500 cycles.
B: No change in appearance such as scratches after 500 times, and change in appearance such as scratches by 1000 times.
C: Less than 500 times, appearance change such as scratches

<Heat resistance (heat resistance creep test)>
As a creep test, a constant load was applied to the test piece for a long time at high temperature, and the amount of deformation and the time until fracture were measured. Specifically, the following 1) to 8) were carried out.
1) The hot-melt resin composition and the coating bar of each example to be tested were placed in an oven at 100°C and preheated.
2) A hot melt resin composition is applied to the surface of the polyurethane (PU) resin layer of the wet film-formed cloth (A) at a 200 µgap (thickness of 200 µm), and immediately bonded to the PU resin layer surface of the wet film-formed cloth (B). did
As the wet film-formed fabric (A) and the wet film-formed fabric (B), a polyurethane resin solution (trade name “Lezamin CU-4340NS” (resin solid content: 30 %, manufactured by Dainichiseika Kogyo Co., Ltd.) is diluted with DMF to a solid content of 15% by mass), coagulated and removed from DMF in a water tank, and then dried to form a PU resin layer. A synthetic imitation leather in which a porous layer having a thickness of 800 to 1000 μm after drying is formed on a base material was used.
3) After curing the laminated product at 25° C./60% RH for 24 hours, the heat resistance was measured according to the following procedure.
4) The oven was set to 170°C. Also, the bonded product was cut to a width of 3 cm and a length of 12 cm or more to obtain a test piece.
5) The end of the test piece was peeled off at the bonded surface, clamps were attached and fixed to the wet film-formed cloth (A) side and the wet film-formed cloth (B) side, respectively, and a weight of 3 kg was hung on one side.
6) After placing the test sample in an oven at 170°C and hanging the test sample, the oven door was quickly closed.
7) After closing the door, let stand for 5 minutes.
8) After 5 minutes had elapsed, the test piece was immediately taken out and left at 170°C for 5 minutes to observe the peeled length and the peeled state, and the heat resistance was evaluated according to the following evaluation criteria.
A: The peeled length is less than 2 cm, and the peeled state is substrate breakage.
B: The peeled length is 2 cm or more and less than 5 cm, and the peeled state is substrate breakage.
C: The peeled length is 5 cm or more, or the peeled state is peeling on the PU resin surface.

10 evaluation film 12 clip 14 weight 16 sample 20 gear oven 22 turntable

Claims (7)

Containing a urethane prepolymer having an isocyanate group, which is a reaction product of a polyol component and a polyisocyanate component,
The polyol component includes a high-molecular-weight polyol component and a low-molecular-weight polyol component,
The polymer polyol component is
Polyester polyol (A1) having a structural unit derived from sebacic acid; Polyester polyol (A2) having a structural unit derived from 1,4-butanediol and a structural unit derived from adipic acid and having a number average molecular weight of 8,000 or more and a polyester polyol (A3) having a number average molecular weight of 6,000 or more having structural units derived from 1,6-hexanediol and structural units derived from adipic acid; at least one polyol selected from the group consisting of ( A) and
At least one polyol (B) selected from the group consisting of a polyester polyol (B1) other than the polyol (A); and a polyether polyol (B2); and a polyol (B) ,
The low-molecular-weight polyol component includes a trifunctional polyol (D) having a molecular weight of 300 or less and having three hydroxyl groups in one molecule,
Moisture-curable urethane satisfying the ratio of the polyol (A) and the trifunctional polyol (D), the trifunctional polyol (D) (mmol) / the polyol (A) (g) = 0.14 to 55 mmol/g. A hot-melt resin composition. The moisture-curable urethane hot-melt resin composition according to claim 1, wherein the polyol ( _B ) contains a polyol (Bb) using a plant-derived raw material. 2. The moisture-curable urethane hot-melt resin composition according to claim 1, wherein the polymer polyol component further contains a polycarbonate polyol (C). The moisture-curable urethane hot-melt resin composition according to claim 3, wherein the polycarbonate polyol (C) contains a polycarbonate polyol ( _Cb ) using a plant-derived raw material. The total amount of the polyol (B) and the polycarbonate polyol (C) is greater than the amount of the polyol (A),
The moisture-curable urethane hot-melt according to claim 3, wherein the total proportion of the polyol (A), the polyol (B), and the polycarbonate polyol (C) with respect to the total amount of the polyol component is 90% by mass or more. Resin composition. a substrate;
A laminate comprising a cured product layer of the moisture-curable urethane hot-melt resin composition according to any one of claims 1 to 5 provided on the substrate. comprising a substrate layer, a skin layer, and an adhesive layer provided therebetween and bonding them together;
A synthetic imitation leather, wherein the adhesive layer is a cured product layer of the moisture-curable urethane hot-melt resin composition according to any one of claims 1 to 5.

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