TWI680997B - Synthetic leather - Google Patents

Abstract

The present invention provides a synthetic leather characterized by having a layer formed by a moisture-curable polyurethane hot-melt resin composition containing a hot-melt urethane prepolymer (i), the heat Melamine carbamate prepolymer (i) is a reactant of polyol (A) and polyisocyanate (B) containing alicyclic polyester polyol (a1). The aforementioned polyol (A) preferably further contains polyoxypropylene glycol (a2). The moisture-curable polyurethane hot-melt resin composition preferably further contains a hindered amine compound (ii) and a triazole compound (iii). The synthetic leather of the present invention is excellent in weather resistance and adhesion strength, and can be applied as a split leather.

Description

Synthetic leather

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

The moisture-curable polyurethane hot-melt resin composition is widely used in the manufacture of synthetic leather due to its excellent mechanical strength, flexibility, and adhesiveness. Among them, split leather with bottom leather, adhesive layer and skin layer is similar to natural leather in appearance and feel. As the prices of natural leather have increased in recent years, demand has increased.

As a resin composition forming the adhesive layer of the dihull skin, for example, there is disclosed a composition containing a hot-melt urethane prepolymer using aliphatic polyester polyol or the like as a raw material (for example, refer to Patent Document 1) .

However, this composition requires a further increase in strength. In addition, in the application of the two-leather skin, in recent years, from the viewpoint of design, various skin layers have been used. For example, when a light-colored skin layer is used, in order not to impair the appearance, the adhesive layer is also used. Requires excellent weather resistance that does not change color over time. However, the actual situation is that a material with excellent weather resistance and adhesive strength has not yet been found.

Prior technical literature Patent Literature

Patent Literature 1 Japanese Patent Application Publication No. 2009-297985

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 provides a synthetic leather characterized by having a layer formed by a moisture-curable polyurethane hot-melt resin composition containing a hot-melt urethane prepolymer (i), the heat Melamine carbamate prepolymer (i) is a reactant of polyol (A) and polyisocyanate (B) containing alicyclic polyester polyol (a1).

The synthetic leather of the present invention has a layer with strong adhesive strength (especially initial adhesive strength) and excellent weather resistance.

Forms for carrying out the invention

The synthetic leather of the present invention has a layer formed by a moisture-curable polyurethane hot-melt resin composition containing a hot-melt urethane prepolymer (i), the hot-melt urethane The ester prepolymer (i) is a reactant of a polyol (A) and a polyisocyanate (B) containing an alicyclic polyester polyol (a1).

The alicyclic polyester polyol (a1) is an essential component in terms of 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 due to the continuous irradiation of sunlight. On the other hand, in the present invention, by using the alicyclic polyester polyol (a1), good initial strength and weather resistance due to cohesion can be obtained (especially even under continuous sunlight irradiation Hardening layer with excellent discoloration resistance). In addition, in the embodiment of the present invention, the weather resistance of a QUV weather resistance tester (manufactured by Q-LAB Corporation) equipped with a UVA-340 lamp of 295 to 365 nm in the short-wavelength region that faithfully simulates sunlight is shown. The results of sex tests.

Examples of the alicyclic polyester polyol (a1) include a reactant 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 The reactants of polybasic acid, etc. Furthermore, the reactant can be obtained by a well-known esterification reaction.

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

As the aforementioned aliphatic polybasic acid, for example, succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, sebacic acid, dodecanedioic acid, eicosanedioic acid, Citraconic acid, itaconic acid, citraconic anhydride, itaconic anhydride, etc. These compounds may be used alone or in combination of two or more.

As the aforementioned aliphatic compound having two or more hydroxyl groups, for example, 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 Alcohol, tetraethylene glycol, neopentyl glycol, 1,3-butanediol, 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-pentanediol , Trimethylolethane, trimethylolpropane, pentaerythritol and other compounds. These compounds may be used alone or in combination of two or more. Among these, from the viewpoint of obtaining more excellent weather resistance and adhesion strength, it is preferable to use 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, and new Pentylene glycol, 3-methyl-1,5-pentanediol, from the viewpoint of having a branched structure, the cohesion is further increased to obtain more excellent weather resistance and subsequent strength, preferably neopentyl Alcohol and/or 3-methyl-1,5-pentanediol.

As the alicyclic polybasic acid, for example, cyclohexane dicarboxylic acid, cyclopentane dicarboxylic acid, cyclohexane diadipate, or the like can be used. These compounds may be used alone or in combination of two or more. Among these, from the viewpoint of obtaining more excellent weather resistance and adhesive strength, it is preferable to use cyclohexane dicarboxylic acid and/or cyclohexane diadipate.

The number average molecular weight of the aforementioned alicyclic polyester polyol (a1) is preferably in the range of 400 to 10,000, more preferably in the range of 500 to 5,000, particularly from the viewpoint of obtaining more excellent weather resistance and adhesive strength. The preferred range is 600~3,000. 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 and more preferably 20 to 80 from the viewpoint of obtaining more excellent weather resistance and adhesive strength. The range of mass% is particularly preferably in the range of 30 to 70 mass%, and more preferably in the range of 30 to 50 mass%.

As the polyol (A), other polyols that can be used other than the alicyclic polyester polyol (a1), for example, polyester polyols other than the alicyclic polyester polyol (a1) can be used Alcohol, polyether polyol, polycarbonate polyol, polybutadiene polyol, dimer diol, acrylic polyol, etc. These polyols can 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 aforementioned (a1) can be alleviated, and the coating property can be improved by reducing the viscosity to improve the dihedron From the point of view of aesthetics and manufacturing stability, it is preferable to use polyether polyol, and more preferably polyoxypropylene glycol (a2).

When the content of the aforementioned polyoxypropylene glycol (a2) is used, from the viewpoint of further improving the low viscosity while maintaining weather resistance and adhesion strength, it is preferably in the range of 5 to 90% by mass in the polyol (A) It is more preferably in the range of 10 to 80% by mass, and particularly preferably in the range of 30 to 70% by mass.

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

From the viewpoint of mechanical strength, the number average molecular weight of the aforementioned other polyols is preferably in the range of 500 to 10,000, and more preferably in the range of 700 to 5,000. In addition, when polyoxypropylene glycol (a2) is used as the aforementioned other polyol, the number average molecular weight is preferably in the range of 1,100 to 5,000, and more preferably in the range of 1,500 to 3,000, from the viewpoint of further improving low viscosity. Scope. In addition, the number average molecular weight of the said other polyol shows the value measured similarly to the number average molecular weight of the said alicyclic polyester polyol (a1).

As the aforementioned polyisocyanate (B), polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate, carbodiimide modified diphenylmethane diisocyanate, xylylene diisocyanate, phenylene Aromatic polyisocyanates such as diisocyanate, toluene diisocyanate, naphthalene diisocyanate, etc.; hexamethylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, tetramethyl xylylene Aliphatic or alicyclic polyisocyanates such as diisocyanate, etc. These polyisocyanates can be used alone or in combination of two or more. Among these, from the viewpoint of obtaining excellent reactivity and peel strength, it is preferable to use an aromatic polyisocyanate, and more preferably diphenylmethane diisocyanate.

The use amount of the aforementioned polyisocyanate (B) 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), more preferably 10 to 30% by mass range.

The hot-melt urethane prepolymer (i) is obtained by reacting the polyol (A) with the polyisocyanate (B), and has a moisture-curable polycarbamic acid that can be applied in air or coated Moisture present in the base material of the ester hot-melt resin composition reacts to form an isocyanate group of a cross-linked structure.

As a method for manufacturing the hot-melt urethane prepolymer (i), for example, the polyhydric alcohol (A) can be added to the reaction vessel containing the polyisocyanate (B) by adding the polyisocyanate ( B) The isocyanate group to be produced is reacted under the condition that the hydroxyl group of the polyol (A) becomes excessive.

When manufacturing the hot-melt urethane prepolymer (i), the equivalent ratio of the isocyanate group possessed by the polyisocyanate (B) to the hydroxyl group possessed by the polyol (A) (isocyanate group /Hydroxyl), from the viewpoint of obtaining more excellent peel strength, it is preferably in the range of 1.1 to 5, more preferably in the range of 1.5 to 3.

The content of isocyanate groups (hereinafter, referred to as "NCO%") of the hot-melt urethane prepolymer (i) obtained by the above method, from the viewpoint of obtaining more excellent peel strength, is It is preferably in the range of 1.7 to 5, more preferably in the range of 1.8 to 3. In addition, the NCO% of the said hot-melt urethane prepolymer (i) shows the value measured by the potentiometric titration method based on JIS K1603-1:2007.

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

As the aforementioned other additives, for example, weather stabilizers, hardening catalysts, adhesion-imparting agents, plasticizers, fillers, dyes, pigments, fluorescent whitening agents, silane coupling agents, waxes, and thermoplastic resins can be used. These additives can be used alone or in combination of two or more. Among these, from the viewpoint of obtaining more excellent weather resistance, it is preferable to use a weather-resistant stabilizer.

As the weather-resistant 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 weathering stabilizers can be used alone or in combination of two or more. Among these, from the viewpoint of obtaining more excellent weather resistance, 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).

The hindered amine compound (ii) captures free radicals generated by photodegradation, for example, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, sebacic acid can be used Bis(1,2,2,6,6-pentamethylpiperidin-4-yl)ester, (2,2,6,6-tetramethyl-4-piperidinyl)1,2,3 ,4-butane tetracarboxylate, (1,2,2,6,6-pentamethyl-4-piperidinyl) 1,2,3,4-butane tetracarboxylate, (mix 2 ,2,6,6-tetramethyl-4-piperidinyl/tridecyl) 1,2,3,4-butane tetracarboxylate, (mixed 1,2,2,6,6-pentamethyl Yl-4-piperidinyl/tridecyl) 1,2,3,4-butane tetracarboxylate, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl -1,3,8-triazaspiro[4.5]decane-2,4-dione, etc. These compounds may be used alone or in combination of two or more.

The content of the hindered amine compound (ii) is preferably 0.01 to 10 parts by mass relative to 100 parts by mass of the hot-melt carbamate prepolymer (i) from the viewpoint of obtaining more excellent weather resistance. The range of parts is more preferably 0.05 to 5 parts by mass, and particularly preferably 0.1 to 3 parts by mass.

The aforementioned triazole compound (iii) can prevent discoloration, for example, N,N-bis(2-ethylhexyl)-[(1,2,4-triazol-1-yl)methyl]amine can be used; 2 -[2-Hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-(2'-hydroxy-3',5'-di-third Butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-third butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-( 2'-hydroxy-3'-third pentyl-5'-isobutylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-isobutyl-5'-methyl Phenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-isobutyl-5'-propylphenyl)-5-chlorobenzotriazole, 2-(2' -Hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-[2'-hydroxyl -5'-(1,1,3,3-tetramethyl)phenyl]benzotriazole and other benzotriazole compounds. These triazole compounds can be used alone or in combination of two or more. Among these, from the viewpoint of obtaining more excellent weather resistance, it is preferable to use a benzotriazole compound.

The content when the triazole compound (iii) is used is preferably 0.01 to 100 parts by mass of the hot-melt carbamate prepolymer (i) from the viewpoint of obtaining more excellent weather resistance. The range of 10 parts by mass is more preferably 0.05 to 5 parts by mass, and particularly preferably 0.1 to 3 parts by mass.

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

The synthetic leather of the present invention has a layer formed by the moisture-curable polyurethane hot-melt resin composition and having excellent weather resistance. As a result, the aforementioned layer is free from discoloration caused by the continuous degradation caused by sunlight, etc., so that the utilization range of the erin skin with increased demand can be expanded more than in the past.

The above-mentioned two-leather skin is provided with a bottom 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 of the two-leather skin. Hereinafter, a method of manufacturing the dihedrin when the moisture-curable polyurethane hot-melt resin composition is used in the adhesive layer will be described.

As the base leather, well-known ones can be used. For example, natural leather such as cows, horses, sheep, goats, deer, and kangaroos can be used, and the skin and nipple layers have been removed. These base leathers are preferably those that have gone through the well-known tanning steps, tanning steps, and dyeing and finishing steps. The thickness of the aforementioned bottom leather is appropriately determined according to the intended use, for example, in the range of 0.1 to 2 mm.

As a method of forming the adhesive layer on the base leather, for example, the base leather may be coated with the moisture-curable polyurethane hot-melt resin composition melted at 50 to 130°C, for example. Method: On the release paper, for example, a method of applying the moisture-curable polyurethane hot-melt resin composition melted at 50 to 130° C., and then bonding the hardened layer to the base leather; On the skin layer formed on the release paper, for example, apply the moisture-curable polyurethane hot-melt resin composition melted at 50 to 130°C, and then apply the hardened layer to the primer leather Methods, etc.

In any of the aforementioned methods, as a method of applying the moisture-curable polyurethane hot-melt resin composition, for example, a roll coater, a knife coater, a spray coater, a gravure coater, and a corner are used Method of wheel coater, T-shaped die coater, applicator, etc.

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

The thickness of the hardened 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, well-known ones can be used, and for example, solvent-based urethane resins, water-based urethane resins, solvent-free urethane resins, solvent-based acrylic resins, and water-based resins can be used. Acrylic resin, etc. These resins can be used alone or in combination of two or more.

As a heating method when removing the solvent in the resin for forming the skin layer, for example, a method of performing 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.

[Example]

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

[Example 1]

In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux cooler, add 40 parts by mass of alicyclic polyester polyol (make neopentyl glycol, 3-methyl-1,5-pentane Alcohol and cyclohexane dicarboxylic acid reactor, number average molecular weight: 1,000, hereinafter referred to as "alicyclic PEs1"), 60 parts by mass of polyoxypropylene glycol (number average molecular weight: 2,000, hereinafter referred to as "PPG2000") and mixed, By heating under reduced pressure at 100° C., the water in the flask was dehydrated to 0.05% by mass or less.

Next, the inside of the flask was cooled to 90°C, 26.5 parts by mass of 4,4′-diphenylmethane diisocyanate (hereinafter referred to as “MDI”) melted at 70°C was added, and the reaction was carried out at 110°C under a nitrogen atmosphere. After 3 hours, until the isocyanate group content became constant, a hot-melt urethane prepolymer with NCO%=2.4% by mass was obtained.

Next, a solvent-based urethane resin ("Crisvon TF-50P-C" manufactured by DIC Corporation) was coated on the release paper so that the film thickness after drying became 30 μm, and dried at 120° C. for 10 minutes, and Get the epidermis. Next, on this skin layer, using a notched wheel coater, the aforementioned hot-melt urethane prepolymer melted at 110°C for 1 hour was applied so that the thickness became 30 μm, and then the skin and the natural leather were removed from the bovine natural leather. The nipple layer is attached to the leather-made bottom leather, and then placed at a temperature of 23° C. and a relative humidity of 65% for 3 days to obtain a second palm skin.

[Examples 2 to 4, Comparative Examples 1 to 2]

Except that the types and blending amounts of the polyol (A) and the polyisocyanate (B) shown in Table 1 were used to obtain a hot-melt urethane prepolymer, dicole skin was obtained in the same manner as in Example 1.

[Example 5]

In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux cooler, 40 parts by mass of alicyclic PEs and 60 parts by mass of PPG2000 were added and mixed, and the flask was heated under reduced pressure at 100°C. The water in it is dehydrated to below 0.05% by mass.

Next, the inside of the flask was cooled to 90°C, 26.5 parts by mass of MDI melted at 70°C was added, and the reaction was carried out at 110°C for about 3 hours under a nitrogen atmosphere until the isocyanate content became constant, obtaining NCO%=2.4 Mass% hot melt urethane prepolymer. To this, 0.5 mass% of bis(1,2,2,6,6-pentamethylpiperidine-4-yl) sebacate (Sansan LS-765 manufactured by Sankyo Co., Ltd.) is blended, the following Referred to as "LS-765"), a moisture-curable polyurethane hot-melt resin composition was obtained.

Next, a solvent-based urethane resin ("Crisvon TF-50P-C" manufactured by DIC Corporation) was coated on the release paper so that the film thickness after drying became 30 μm, and dried at 120° C. for 10 minutes, and Get the epidermis. Next, on this skin layer, the above-mentioned moisture-curable polyurethane hot-melt resin composition melted at 110° C. for 1 hour was applied to a thickness of 30 μm using a notched wheel coater. The natural leather is stripped of the epidermis and the nipple layer, adhered to the tanned bottom leather, and then placed at a temperature of 23°C and a relative humidity of 65% for 3 days to obtain a second palm skin.

[Example 6]

In addition to the aforementioned moisture-curable polyurethane hot-melt resin composition, 0.5% by mass of a benzotriazole compound (manufactured by BASF) is added to the hot-melt polyurethane prepolymer. Except for Tinuvin (registered trademark) 234", hereinafter referred to as "T234"), in the same manner as in Example 1, a moisture-curable polyurethane hot-melt resin composition was obtained, and a dihull skin was produced.

[Examples 7-9]

In addition to the types and amounts of polyol (A), polyisocyanate (B), hindered amine compound (ii) and triazole compound (iii) as shown in Table 2, moisture-curable polyurethanes are obtained Except for the hot-melt resin composition, in the same manner as in Example 6, a two-piece skin was obtained.

[Measurement method of number average molecular weight]

The number average molecular weights of the polyols and the like used in the examples and comparative examples represent the values measured by the gel permeation chromatography (GPC) method under the following conditions.

Measuring device: High-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation)

Pipe string: The following pipe string made by Tosoh Corporation is connected in series and used.

"TSKgel G5000" (7.8mmI.D.×30cm)×1

"TSKgel G4000" (7.8mmI.D.×30cm)×1

"TSKgel G3000" (7.8mmI.D.×30cm)×1

"TSKgel G2000" (7.8mmI.D.×30cm)×1

Detector: RI (Differential Refractometer)

Column temperature: 40℃

Eluent: Tetrahydrofuran (THF)

Flow rate: 1.0mL/min

Injection volume: 100 μL (sample concentration of 0.4% by mass in tetrahydrofuran solution)

Standard sample: Use the following standard polystyrene to prepare a calibration curve.

(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 on a release paper placed on a hot plate previously heated to 110°C at 100 µm. This coated product was stored at 25° C. and 50% humidity for 24 hours, and cured to obtain a film. Using this film, a UVA weather resistance tester "QUV/basic" equipped with a UVA-340 light bulb (UV exposure: 0.78W/m ² , temperature 45°C) was used to perform UV irradiation tests, according to the color change before and after UV irradiation The difference (ΔE) was evaluated as follows.

"4": △E is 10 or less.

"3": △E is greater than 10 and less than 13.

"2": △E is greater than 13 and less than 15.

"1": △E is greater than 15.

[The evaluation method of the next strength]

After the urethane prepolymers obtained in Examples and Comparative Examples were melted at 120°C for 1 hour, the PET film placed on a hot plate previously heated to 110°C was coated at 100 µm. Immediately after coating, the PET film was removed from the hot plate, and another PET film was laminated with a hand roll immediately. After bonding, the test piece was cut to a width of 1 inch, and a digital tensile meter ("DS2-220N" manufactured by IMADA Co., Ltd.) was used to measure the peel strength between PETs after bonding for 1 minute. The initial strength was evaluated as follows .

"T": 5N/inch or more

"F": less than 5N/inch

[Measurement method of low viscosity]

After the urethane prepolymers obtained in 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 number: 50 rpm), and evaluated as follows .

"T": less than 4,000mPa‧s

"F": 4,000mPa‧s or more

The abbreviated symbols in Table 1 are the following.

"Alicyclic PEs2": 1,4-cyclohexanedimethanol and adipic acid reacted, number average molecular weight: 1,000

"Aromatic PEs": Reactors of diethylene glycol, neopentyl glycol and terephthalic anhydride, number average molecular weight: 1,000

"Fatty PEs": those reacting 1,4-butanediol and adipic acid, number average molecular weight: 1,000)

It can be seen that the synthetic leather of the present invention has a cured layer of a moisture-curable polyurethane hot-melt resin composition excellent in weather resistance, adhesion strength and low viscosity.

On the other hand, in Comparative Example 1, an aromatic polyester polyol was used instead of the alicyclic polyester polyol (a1). Although the adhesive strength was excellent, the weather resistance and low viscosity were poor.

In Comparative Example 2, an aliphatic polyester polyol was used instead of the alicyclic polyester polyol (a1), and the subsequent strength was poor.

Claims (7)

A synthetic leather characterized by having a layer formed by a moisture-curable polyurethane hot-melt resin composition containing a hot-melt urethane prepolymer (i), the hot-melt amine group Formate prepolymer (i) is a reactant of polyol (A) and polyisocyanate (B) containing alicyclic polyester polyol (a1), the hot-melt amino formate prepolymer (i) ) Has an isocyanate group content rate in the range of 1.7 to 5, and the polyol (A) further contains polyoxypropylene glycol (a2). The synthetic leather according to claim 1, which further contains a hindered amine compound (ii). The synthetic leather according to claim 2, wherein the content of the hindered amine compound (ii) is in the range of 0.01 to 10 parts by mass relative to 100 parts by mass of the hot-melt urethane prepolymer (i). The synthetic leather according to claim 2, which further contains a triazole compound (iii). The synthetic leather according to claim 4, wherein the content of the triazole compound (iii) is in the range of 0.01 to 10 parts by mass relative to 100 parts by mass of the hot-melt urethane prepolymer (i). The synthetic leather according to claim 4 or 5, wherein the triazole compound (iii) is a benzotriazole compound. For the synthetic leather of claim 1 or 2, it is split leather.