WO2018110106A1

WO2018110106A1 - Synthetic leather

Info

Publication number: WO2018110106A1
Application number: PCT/JP2017/038611
Authority: WO
Inventors: 伸吾竹田; 豊邦藤原
Original assignee: Dic株式会社
Priority date: 2016-12-16
Filing date: 2017-10-26
Publication date: 2018-06-21
Also published as: JP6355010B1; TWI680997B; KR102269803B1; CN109963980A; TW201825552A; JPWO2018110106A1; KR20190045334A; CN109963980B

Abstract

The present invention provides a synthetic leather which is characterized by having a layer that is formed from a moisture-curable polyurethane hot melt resin composition which contains (i) a hot melt urethane prepolymer that is a reaction product of (A) a polyol containing (a1) an alicyclic polyester polyol and (B) a polyisocyanate. It is preferable that the polyol (A) additionally contains (a2) a polyoxypropylene glycol. It is preferable that the moisture-curable polyurethane hot melt resin composition additionally contains (ii) a hindered amine compound and (iii) a triazole compound. A synthetic leather according to the present invention has excellent weather resistance and bonding strength, and is suitable for use as a split leather.

Description

Synthetic leather

The present invention relates to a synthetic leather having a cured product layer of a moisture curable polyurethane hot melt resin composition.

Moisture curable polyurethane hot melt resin compositions are widely used in the production of synthetic leather because they are excellent in mechanical strength, flexibility, adhesiveness, and the like. Among them, split leather having a floor leather, an adhesive layer, and a skin layer has an appearance and texture similar to those of natural leather, and therefore demand is increasing with the recent increase in prices of natural leather.

As the resin composition forming the adhesive layer of the split leather, for example, a composition containing a hot melt urethane prepolymer using an aliphatic polyester polyol or the like as a raw material is disclosed (see, for example, Patent Document 1). ).

However, such a composition has been required to further improve the adhesive strength. In addition, for split leather applications, various colored skin layers may be used in recent years from the viewpoint of design.For example, if a light skin layer is used, the adhesive layer should not be damaged. Is also required to have excellent weather resistance with no discoloration over time. However, in reality, no material that has both excellent weather resistance and adhesive strength has been found yet.

JP 2009-297985 A

The problem to be solved by the present invention is to provide a synthetic leather having a cured layer of a moisture curable polyurethane hot melt resin composition having excellent weather resistance and adhesive strength.

The present invention relates to a moisture curable polyurethane hot melt resin composition comprising a polyol (A) containing an alicyclic polyester polyol (a1) and a hot melt urethane prepolymer (i) which is a reaction product of a polyisocyanate (B). The present invention provides a synthetic leather characterized by having a layer formed of a product.

The synthetic leather of the present invention has a layer having high adhesive strength (particularly, initial adhesive strength) and excellent weather resistance.

The synthetic leather of the present invention is a moisture curable polyurethane hot containing a polyol (A) containing an alicyclic polyester polyol (a1) and a hot melt urethane prepolymer (i) which is a reaction product of a polyisocyanate (B). It has a layer formed of a melt resin composition.

The alicyclic polyester polyol (a1) is an essential component for obtaining excellent weather resistance and adhesive strength. In order to obtain excellent initial adhesive strength, an aromatic polyester polyol using an aromatic compound such as phthalic acid as a raw material is generally used. However, when an aromatic polyester polyol is used, there is a problem of discoloration, particularly due to continuous irradiation of sunlight. On the other hand, in the present invention, by using the alicyclic polyester polyol (a1), a cured layer having excellent initial strength due to cohesive force and weather resistance (particularly, discoloration resistance even during continuous irradiation of sunlight) is obtained. Obtainable. In the examples of the present invention, the weather resistance by a QUV accelerated weathering tester (Q-LAB Corporation) equipped with a UVA-340 lamp that faithfully simulates the short wavelength region of sunlight, 295 to 365 nm. The result of a test is shown.

Examples of the alicyclic polyester polyol (a1) include a reaction product of an alicyclic compound having two or more hydroxyl groups and an aliphatic polybasic acid, an aliphatic compound having two or more hydroxyl groups, and an alicyclic polybase. Examples include a reaction product with an acid. Such a reaction product can be obtained by a known esterification reaction.

As the alicyclic compound having two or more hydroxyl groups, for example, cyclopentanediol, cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A; and these alkylene oxide adducts can be used. These compounds may be used alone or in combination of two or more. Among these, it is preferable to use cyclohexanedimethanol from the standpoint of obtaining further excellent weather resistance and adhesive strength.

Examples of the aliphatic polybasic acid include succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedioic acid, dodecanedioic acid, eicosadic acid, citraconic acid, itaconic acid, citraconic anhydride Itaconic anhydride and the like can be used. These compounds may be used alone or in combination of two or more.

Examples of the aliphatic compound having two or more hydroxyl groups include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7- Heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, neopentyl glycol, 1,3-butane Diol, 2,2-diethyl-1,3-propanediol, 2,2-diethylpropanediol, 3-methyl-1,5-pentanediol, 2-ethyl-2-butyl-1,3-propanediol, 2 -Methyl-1,8-octanediol, 2,4-diethyl-1,5-penta Diol, trimethylol ethane, trimethylol propane, it is possible to use a compound such as pentaerythritol. These compounds may be used alone or in combination of two or more. Among these, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, neopentyl glycol, 3-methyl-1 are obtained from the standpoint of obtaining further excellent weather resistance and adhesive strength. , 5-pentanediol is preferred, and neopentyl glycol and / or 3-methyl is preferred because it has a branched structure and thus has a higher cohesive force and can provide better weather resistance and adhesive strength. 1,5-pentanediol is more preferred.

As the alicyclic polybasic acid, for example, cyclohexanedicarboxylic acid, cyclopentanedicarboxylic acid, cyclohexanediadipate and the like can be used. These compounds may be used alone or in combination of two or more. Among these, it is preferable to use cyclohexanedicarboxylic acid and / or cyclohexanediadipate from the viewpoint that much more excellent weather resistance and adhesive strength can be obtained.

The number average molecular weight of the alicyclic polyester polyol (a1) is preferably in the range of 400 to 10,000, and more preferably in the range of 500 to 5,000, from the viewpoint of obtaining even better weather resistance and adhesive strength. Is more preferable, and a range of 600 to 3,000 is even more preferable. In addition, the number average molecular weight of the said alicyclic polyester polyol (a1) shows the value measured by the gel permeation chromatography (GPC) method.

The content of the alicyclic polyester polyol (a1) is preferably 10% by mass or more in the polyol (A) from the viewpoint of obtaining further excellent weather resistance and adhesive strength, and 20 to 80 The range of mass% is preferable, the range of 30 to 70 mass% is more preferable, and the range of 30 to 50 mass% is more preferable.

Examples of other polyols that can be used in addition to the alicyclic polyester polyol (a1) as the polyol (A) include polyester polyols other than the alicyclic polyester polyol (a1), polyether polyols, and polycarbonate polyols. Polybutadiene polyol, dimer diol, acrylic polyol, and the like can be used. These polyols may be used alone or in combination of two or more. Among these, when used in combination with the alicyclic polyester polyol (a1), the high-viscosity derived from the (a1) can be reduced, and the coating property by lowering the viscosity can be improved. From the viewpoint of improving production stability, it is preferable to use a polyether polyol, and more preferably polyoxypropylene glycol (a2).

The content in the case of using the polyoxypropylene glycol (a2) is 5 to 90% by mass in the polyol (A) from the viewpoint that the low viscosity can be further improved while maintaining the weather resistance and the adhesive strength. The range is preferably 10 to 80% by mass, more preferably 30 to 70% by mass.

In addition, when polyoxypropylene glycol (a2) is used, aliphatic polyester polyol and / or polytetramethylene glycol are used in combination since the balance of weather resistance, adhesive strength, and low viscosity can be further improved. It is preferable to do.

The number average molecular weight of the other polyol is preferably in the range of 500 to 10,000, more preferably in the range of 700 to 5,000, from the viewpoint of mechanical strength. When polyoxypropylene glycol (a2) is used as the other polyol, the number average molecular weight is in the range of 1,100 to 5,000 from the viewpoint of further improving the low viscosity. The range of 1,500 to 3,000 is more preferable. In addition, the number average molecular weight of the said other polyol shows the value obtained by measuring similarly to the number average molecular weight of the said alicyclic polyester polyol (a1).

Examples of the polyisocyanate (B) include polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate isocyanate, xylylene diisocyanate, phenylene diisocyanate, tolylene diisocyanate, naphthalene diisocyanate, and the like; hexamethylene diisocyanate, cyclohexane Aliphatic or alicyclic polyisocyanates such as diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and tetramethylxylylene diisocyanate can be used. These polyisocyanates may be used alone or in combination of two or more. Among these, aromatic polyisocyanate is preferably used, and diphenylmethane diisocyanate is more preferable from the viewpoint that excellent reactivity and peel strength can be obtained.

The amount of the polyisocyanate (B) used is preferably in the range of 5 to 40% by mass in the total mass of the raw materials constituting the hot melt urethane prepolymer (i), and is in the range of 10 to 30% by mass. It is more preferable.

The hot melt urethane prepolymer (i) is obtained by reacting the polyol (A) and the polyisocyanate (B), and is coated with an air or moisture curable polyurethane hot melt resin composition. It has an isocyanate group that can react with moisture present in the substrate to form a crosslinked structure.

As a method for producing the hot melt urethane prepolymer (i), for example, the polyol (A) is put in a reaction vessel containing the polyisocyanate (B), and the isocyanate group of the polyisocyanate (B) is It can manufacture by making it react on the conditions which become excess with respect to the hydroxyl group which a polyol (A) has.

When producing the hot melt urethane prepolymer (i), the equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate group of the polyisocyanate (B) and the hydroxyl group of the polyol (A) is even more excellent. From the viewpoint of obtaining high peel strength, the range is preferably 1.1 to 5, and more preferably 1.5 to 3.

The isocyanate group content (hereinafter abbreviated as “NCO%”) of the hot-melt urethane prepolymer (i) obtained by the above method is 1.7 from the standpoint that even better peel strength is obtained. The range is preferably from 5 to 5, and more preferably from 1.8 to 3. The NCO% of the hot melt urethane prepolymer (i) is a value measured by potentiometric titration in accordance with JIS K1603-1: 2007.

The moisture curable polyurethane hot melt resin composition used in the present invention contains the hot melt urethane prepolymer as an essential component, but may contain other additives as necessary.

Examples of the other additives include a weather stabilizer, a curing catalyst, a tackifier, a plasticizer, a filler, a dye, a pigment, a fluorescent brightening agent, a silane coupling agent, a wax, and a thermoplastic resin. Can do. These additives may be used alone or in combination of two or more. Among these, it is preferable to use a weather resistance stabilizer from the viewpoint that even better weather resistance can be obtained.

As the weather resistance stabilizer, for example, a hindered amine compound (ii), a triazole compound (iii), a hindered phenol compound, a phosphorus compound, or the like can be used. These weather stabilizers may be used alone or in combination of two or more. Among these, it is preferable to use the hindered amine compound (ii), and it is more preferable to use the hindered amine compound (ii) and the triazole compound (iii) from the viewpoint that much more excellent weather resistance is obtained.

The hindered amine compound (ii) supplements radicals generated by photodegradation. For example, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2, sebacate) 2,6,6-pentamethylpiperidin-4-yl), tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, tetrakis (1,2 , 2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, (mixed 2,2,6,6-tetramethyl-4-piperidyl / tridecyl) 1,2,3 , 4-butanetetracarboxylate, (mixed 1,2,2,6,6-pentamethyl-4-piperidyl / tridecyl) 1,2,3,4-butanetetracarboxylate, 8 Acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro [4.5] decane-2,4-dione and the like can be used. These compounds may be used alone or in combination of two or more.

The content of the hindered amine compound (ii) is in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the hot-melt urethane prepolymer (i) from the viewpoint that even better weather resistance is obtained. Preferably, the range is 0.05 to 5 parts by mass, and more preferably 0.1 to 3 parts by mass.

The triazole compound (iii) can prevent discoloration, and includes, for example, N, N-bis (2-ethylhexyl)-[(1,2,4-triazol-1-yl) methyl] amine; 2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chloro Benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-tert-amyl-5'-isobutyl Phenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3′-isobutyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3′-isobutyl-5′-propylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole, Benzotriazole compounds such as 2- (2′-hydroxy-5′-methylphenyl) benzotriazole and 2- [2′-hydroxy-5 ′-(1,1,3,3-tetramethyl) phenyl] benzotriazole Is used. These triazole compounds may be used alone or in combination of two or more. Among these, it is preferable to use a benzotriazole compound from the viewpoint that a further excellent weather resistance can be obtained.

The content in the case of using the triazole compound (iii) is 0.01 to 10 parts by mass with respect to 100 parts by mass of the hot-melt urethane prepolymer (i) from the viewpoint that a further excellent weather resistance is obtained. The range is preferably 0.05 to 5 parts by mass, and more preferably 0.1 to 3 parts by mass.

Next, the synthetic leather of the present invention will be described.

The synthetic leather of the present invention has a layer having excellent weather resistance formed by the moisture-curable polyurethane hot melt resin composition. Thereby, since the said layer does not have discoloration by the deterioration over time by sunlight etc., the use range of the split leather in which the demand is increasing can be expanded more than before.

The split leather includes a floor leather, an adhesive layer, and a skin layer, and the moisture-curable polyurethane hot melt resin composition can be suitably used as an adhesive layer for split leather. Hereinafter, a method for producing split leather when the moisture-curable polyurethane hot melt resin composition is used for the adhesive layer will be described.

As the floor leather, known ones can be used, for example, natural leather such as cattle, horses, sheep, goats, deer, kangaroos, etc., composed of layers obtained by removing the epidermis and nipple layer. Can be used. It is preferable to use those floor leathers that have undergone a known leather making process, tanning process, and dyeing / finishing process. The thickness of the floor leather is appropriately determined according to the intended use, and is, for example, in the range of 0.1 to 2 mm.

Examples of the method for forming the adhesive layer on the floor leather include, for example, a method of applying the moisture-curable polyurethane hot melt resin composition melted at 50 to 130 ° C. on the floor leather, for example. Coating the moisture-curable polyurethane hot melt resin composition melted at 50 to 130 ° C. on the release paper, and then bonding the cured product layer to the floor leather; On the formed skin layer, for example, a method of applying the moisture-curable polyurethane hot melt resin composition melted at 50 to 130 ° C. and then bonding the cured product layer to the floor leather is exemplified. It is done.

In any of the above methods, for example, a roll coater, a knife coater, a spray coater, a gravure coater, a comma coater, a T-die coater, an applicator or the like is used as a method for applying a moisture curable polyurethane hot melt resin composition. A method is mentioned.

After the moisture curable polyurethane hot melt resin composition is applied, it can be cured by a known method.

The thickness of the cured product layer (adhesive layer) of the moisture curable urethane hot melt resin composition is, for example, in the range of 5 to 200 μm.

As the resin for forming the skin layer, known resins can be used, for example, solvent-based urethane resin, water-based urethane resin, solvent-free urethane resin, solvent-based acrylic resin, water-based acrylic resin, etc. Can do. These resins may be used alone or in combination of two or more.

As a heating method for removing the solvent in the resin for forming the skin layer, for example, a method of carrying out at a temperature of 50 to 120 ° C. for 2 to 20 minutes can be mentioned.

The thickness of the skin layer is, for example, in the range of 5 to 100 μm.

Hereinafter, the present invention will be described in more detail using examples.

[Example 1]
A four-necked flask equipped with a thermometer, stirrer, inert gas inlet and reflux condenser was charged with alicyclic polyester polyol (neopentyl glycol, 3-methyl-1,5-pentanediol, and cyclohexanedicarboxylic acid). What was reacted, number average molecular weight: 1,000, hereinafter abbreviated as “alicyclic PEs1”), 40 parts by mass, polyoxypropylene glycol (number average molecular weight; 2,000, hereinafter abbreviated as “PPG2000”) .) Was added, mixed, and heated at 100 ° C. under reduced pressure to dehydrate until the water content in the flask was 0.05% by mass or less.
Next, the flask was cooled to 90 ° C., 26.5 parts by mass of 4,4′-diphenylmethane diisocyanate (hereinafter abbreviated as “MDI”) melted at 70 ° C. was added, and the isocyanate group content was increased under a nitrogen atmosphere. By making it react at 110 degreeC for about 3 hours until it became constant, the hot-melt urethane prepolymer of NCO%; 2.4 mass% was obtained.
Next, a solvent-based urethane resin (“Crisbon TF-50P-C” manufactured by DIC Corporation) was applied on the release paper so that the film thickness after drying was 30 μm, and dried at 120 ° C. for 10 minutes. A skin layer was obtained. Next, the hot melt urethane prepolymer melted at 110 ° C. for 1 hour was coated on the skin layer to a thickness of 30 μm using a comma coater, and then the skin and nipple layer were formed from natural cow leather. And was bonded to a leather floor leather, and then left for 3 days under conditions of a temperature of 23 ° C. and a relative humidity of 65% to obtain split leather.

[Examples 2 to 4, Comparative Examples 1 and 2]
Split leather was obtained in the same manner as in Example 1 except that the hot melt urethane prepolymer was obtained with the types and blending amounts of polyol (A) and polyisocyanate (B) as shown in Table 1.

[Example 5]
By placing 40 parts by mass of alicyclic PEs1 and 60 parts by mass of PPG2000 in a four-necked flask equipped with a thermometer, stirrer, inert gas inlet and reflux condenser, and mixing and heating at 100 ° C. under reduced pressure The flask was dehydrated until the water content in the flask was 0.05% by mass or less.
Next, the inside of the flask is cooled to 90 ° C., 26.5 parts by mass of MDI melted at 70 ° C. is added, and the reaction is performed at 110 ° C. for about 3 hours under a nitrogen atmosphere until the isocyanate group content becomes constant. %: 2.4% by mass of a hot-melt urethane prepolymer was obtained. To this, bis (1,2,2,6,6-pentamethylpiperidin-4-yl) sebacate (manufactured by Sankyo Co., Ltd., “Sanol LS-765”, hereinafter abbreviated as “LS-765”) is 0. .5% by mass was added to obtain a moisture curable polyurethane hot melt resin composition.
Next, a solvent-based urethane resin (“Crisbon TF-50P-C” manufactured by DIC Corporation) was applied on the release paper so that the film thickness after drying was 30 μm, and dried at 120 ° C. for 10 minutes. A skin layer was obtained. Next, the moisture curable polyurethane hot melt resin composition melted at 110 ° C. for 1 hour is applied onto the skin layer so as to have a thickness of 30 μm using a comma coater. The epidermis and nipple layer were removed and bonded to the leather floor leather, and then left for 3 days under conditions of a temperature of 23 ° C. and a relative humidity of 65% to obtain split leather.

[Example 6]
In the moisture curable polyurethane hot melt resin composition, 0.5 is added to the hot melt urethane prepolymer, a benzotriazole compound (“Tinvin (registered trademark) 234” manufactured by BASF, hereinafter abbreviated as “T234”)). A moisture curable polyurethane hot melt resin composition was obtained in the same manner as in Example 1 except that it was further blended in mass% to produce a split leather.

[Examples 7 to 9]
Except that the moisture curable polyurethane hot melt resin composition was obtained with the types and amounts of polyol (A), polyisocyanate (B), hindered amine compound (ii) and triazole compound (iii) as shown in Table 2. In the same manner as in Example 6, a split leather was obtained.

[Measurement method of number average molecular weight]
The number average molecular weights of polyols and the like used in Examples and Comparative Examples show values measured under the following conditions by gel permeation chromatography (GPC) method.

Measuring device: High-speed GPC device (“HLC-8220GPC” manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series.
"TSKgel G5000" (7.8 mm ID x 30 cm) x 1 "TSKgel G4000" (7.8 mm ID x 30 cm) x 1 "TSKgel G3000" (7.8 mm ID x 30 cm) x 1 “TSKgel G2000” (7.8 mm ID × 30 cm) × 1 detector: RI (differential refractometer)
Column temperature: 40 ° C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL / min Injection amount: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4 mass%)
Standard sample: A calibration curve was prepared using the following standard polystyrene.

(Standard polystyrene)
"TSKgel standard polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

[Evaluation method of weather resistance]
The urethane prepolymers obtained in Examples and Comparative Examples were melted at 110 ° C. for 1 hour, and then coated at 100 μm on release paper placed on a hot plate preheated to 110 ° C. This coated product was stored at 25 ° C. and 50% humidity for 24 hours and cured to obtain a film. Using this film, a UV irradiation test was conducted using a QUV accelerated weathering tester “QUV / basic” equipped with a UVA-340 bulb (UV irradiation amount: 0.78 W / m ² , temperature 45 ° C.). The weather resistance was evaluated as follows by the difference in color change (ΔE) before and after UV irradiation.
“4”; ΔE is 10 or less.
“3”; ΔE is more than 10 and 13 or less.
“2”; ΔE exceeds 13 and is 15 or less.
“1”; ΔE exceeds 15.

[Evaluation method of adhesive strength]
The urethane prepolymers obtained in the examples and comparative examples were melted at 120 ° C. for 1 hour, and then coated at 100 μm on a PET film placed on a hot plate preheated to 110 ° C. Immediately after the coating, the PET film was removed from the hot plate, and another PET film was immediately bonded with a hand roller. After bonding, the test piece was cut into a 1-inch width, and using a digital force gauge (“DS2-220N” manufactured by Imaada Co., Ltd.), the peel strength between the PET one minute after bonding was measured, and the initial strength Was evaluated as follows.
“T”; 5N / inch or more “F”; less than 5N / inch

[Measurement method of low viscosity]
The urethane prepolymers obtained in the examples and comparative examples were melted at 120 ° C. for 1 hour, 1 ml was sampled, and the melt viscosity was measured with a cone plate viscometer (40P cone, rotor rotation speed: 50 rpm). And evaluated as follows.
“T”; less than 4,000 mPa · s “F”; 4,000 mPa · s or more

Abbreviations in Table 1 are as follows.
"Alicyclic PEs2": 1,4-cyclohexanedimethanol and adipic acid reacted, number average molecular weight; 1,000
“Aromatic PEs”: reaction of diethylene glycol, neopentyl glycol, and terephthalic anhydride, number average molecular weight; 1,000
“Aliphatic PEs”: 1,4-butanediol and adipic acid reacted, number average molecular weight; 1,000)

The synthetic leather of the present invention was found to have a cured product layer of a moisture curable polyurethane hot melt resin composition excellent in weather resistance, adhesive strength, and low viscosity.

On the other hand, Comparative Example 1 is an embodiment in which an aromatic polyester polyol is used instead of the alicyclic polyester polyol (a1). However, although the adhesive strength is excellent, the weather resistance and the low viscosity are poor. .

Comparative Example 2 was an embodiment in which an aliphatic polyester polyol was used instead of the alicyclic polyester polyol (a1), but the adhesive strength was poor.

Claims

It is formed by a moisture curable polyurethane hot melt resin composition containing a polyol (A) containing an alicyclic polyester polyol (a1) and a hot melt urethane prepolymer (i) which is a reaction product of a polyisocyanate (B). Synthetic leather characterized by having a layer.
The synthetic leather according to claim 1, wherein the polyol (A) further contains polyoxypropylene glycol (a2).
The synthetic leather according to claim 1 or 2, further comprising a hindered amine compound (ii).
The synthetic leather according to claim 3, wherein the content of the hindered amine compound (ii) is in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the hot melt urethane prepolymer (i).
The synthetic leather according to claim 3 or 4, further comprising a triazole compound (iii).
The synthetic leather according to claim 5, wherein the content of the triazole compound (iii) is in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the hot melt urethane prepolymer (i).
The synthetic leather according to claim 5 or 6, wherein the triazole compound (iii) is a benzotriazole compound.
The synthetic leather according to any one of claims 1 to 7, which is split leather.