CN110128614B - Solvent-free polyurethane resin for high-stripping foaming layer and preparation method and application thereof - Google Patents

Abstract

The invention discloses a solvent-free polyurethane resin for a high-stripping foaming layer and a preparation method and application thereof. According to the invention, a low molecular weight polyamide resin polyol structure is introduced, so that the polarity and the strength of a polyurethane system are improved, the bonding strength of a solvent-free middle layer/foaming layer and a water-based polyurethane surface layer is improved, and the heat resistance of a foaming layer made of solvent-free resin is improved.

Description

Solvent-free polyurethane resin for high-stripping foaming layer and preparation method and application thereof

Technical Field

The invention relates to a solvent-free polyurethane resin for leather, and a preparation method and application thereof.

Background

In recent years, the solvent-free polyurethane leather resin is continuously developed and strengthened in the market, and the product types are gradually enriched. The synthetic leather is prepared by using the solvent-free resin, organic solvents are not used, process waste residues are avoided, the residual quantity of volatile organic compounds is low, and the market acceptance is high. In 2006, US20060083929a1 disclosed a method for producing solvent-free polyurethane and a method for producing solvent-free synthetic leather. Chinese patent documents or patent application documents CN201410797159.0, CN201510443390.4, CN201510554905.8, CN201510634193.0, CN201510710090.8, CN201610464625.2, and CN201711068852.4 also disclose a technology for preparing environment-friendly synthetic leather by using aqueous polyurethane resin as a surface layer and solvent-free polyurethane resin as a foaming layer/bonding layer. However, when the foaming layer made of solvent-free polyurethane resin and the surface layer made of aqueous polyurethane resin used in the above technology are bonded, only physical covalent bonding force is generated, so that the bonding is not firm, the surface layer and the foaming layer are easy to separate, the peeling load is poor, and the application is limited. The main reason is that hydrophilic groups, generally carboxylic acid groups, and some small amount of sulfonic acid groups need to be introduced during the synthesis of the aqueous resin. The acidity of the carboxylic acid and the sulfonic acid reduces the curing reaction speed of the solvent-free resin on the aqueous surface layer, affects the adhesion between the aqueous surface layer and the solvent-free foamed layer, and the carboxylic acid reacts with part of isocyanate in the solvent-free resin to generate carbon dioxide gas, so that air barrier is formed between the surface layer and the foamed layer, and the adhesion effect is further reduced.

Disclosure of Invention

The invention aims to provide a solvent-free polyurethane resin for a high-peel foaming layer, and a preparation method and application thereof, so as to solve the problem of poor adhesion between the solvent-free polyurethane resin for the foaming layer and a water-based surface layer in the prior art, and improve the high temperature resistance of the solvent-free polyurethane synthetic leather.

The solvent-free polyurethane resin for the high-stripping foaming layer comprises a resin A component and a resin B component, wherein the ratio of the mole number of active hydrogen in the resin A component to the mole number of isocyanate groups in the resin B component is 0.95: 1-1: 1.05;

the resin A component contains low molecular weight polyamide resin polyol, the resin B component contains isocyanate, and the isocyanate is a mixture of aromatic isocyanate and aliphatic isocyanate.

Preferably, the resin A component contains the following components in parts by mass:

the polyol A is polyester polyol A and/or polyether polyol A; the functionality of the polyether polyol A is 2-3, and the hydroxyl value is 12.5-58.0 mgKOH/g; preferred is a mixture of polyether polyol A with 2 functionality and polyether polyol A with 3 functionality, and the mass ratio of the polyether polyol A with 2 functionality to the polyether polyol A with 3 functionality is 4: 6-7: 3.

The polyether polyol A is prepared by polymerizing more than one of ethylene glycol, diethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, ethanolamine, diethanolamine and triethanolamine with ethylene oxide and/or propylene oxide as an initiator;

the polyester polyol A is prepared by esterification reaction of organic dicarboxylic acid containing 4-10 carbon atoms and micromolecular polyol containing 2-6 carbon atoms; a functionality of 2 to 3 and a hydroxyl value of 54 to 114 mgKOH/g;

the organic dicarboxylic acid is more than one of adipic acid, succinic acid, glutaric acid, suberic acid, sebacic acid, azelaic acid, phthalic acid, terephthalic acid, isophthalic acid, decanedicarboxylic acid and maleic acid;

the micromolecular polyalcohol is more than one of ethylene glycol, diethylene glycol, 1, 2-or 1, 3-propylene glycol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, glycerol and trimethylolpropane;

the polyester polyol A can also be more than one of polycaprolactone polyol and polycarbonate polyol.

The number average molecular weight of the low molecular weight polyamide resin polyol is 700-2000, and the low molecular weight polyamide resin polyol is preferably a reaction product of dibasic acid, diamine and alcohol amine; the preparation method can be found in CN 104231260A;

the chain extender is more than one of ethylene glycol, diethylene glycol, 1, 4-butanediol, 1, 6-hexanediol, 1, 3-propanediol and 3-methyl-1, 5-pentanediol;

the leveling agent is more than one of modified polysiloxane BYK-354, BYK-9565, BYK-354, BYK-3550 and BYK-320;

the foaming agent is water;

the defoaming agent is more than one of polyether modified siloxane BYK-A525, BYK-066N, BYK-530, BYK-A535, BYK-088 and BYK-1794.

The resin B component comprises the following components in parts by mass:

30-60 parts of isocyanate;

40-70 parts of polyol B;

0-20 parts of low molecular weight polyamide resin polyol.

The resin B component also contains an antioxidant and a side reaction inhibitor, wherein the mass of the antioxidant is 0-0.10 wt% of the total mass of the resin B component, and the mass of the side reaction inhibitor is 30-100 ppm of the total mass of the resin B component.

The isocyanate is a mixture of aromatic isocyanate and aliphatic isocyanate, and the mass ratio of the aromatic isocyanate to the aliphatic isocyanate is 7: 1-30: 1;

the aromatic isocyanate is more than one of diphenylmethane diisocyanate, toluene diisocyanate, p-phenylene diisocyanate, naphthalene diisocyanate and polymethylene polyphenyl isocyanate;

the aliphatic isocyanate is more than one of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and cyclohexane dimethylene diisocyanate;

the polyol B is polyether polyol B and/or polyester polyol B;

the polyether polyol B is prepared by polymerizing more than one of ethylene glycol, diethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, ethanolamine, diethanolamine and triethanolamine with ethylene oxide and/or propylene oxide as an initiator; a functionality of 2 to 3 and a hydroxyl value of 12.5 to 58.0 mgKOH/g;

the polyester polyol B is prepared by esterification and polymerization reaction of organic dicarboxylic acid containing 4-10 carbon atoms and micromolecular polyol containing 2-6 carbon atoms, the hydroxyl value is 54-114 mgKOH/g, and the functionality is 2-3;

the organic dicarboxylic acid is preferably at least one of adipic acid, succinic acid, glutaric acid, suberic acid, sebacic acid, azelaic acid, phthalic acid, terephthalic acid, isophthalic acid, decanedicarboxylic acid and maleic acid;

the small molecular polyol is preferably more than one of ethylene glycol, diethylene glycol, 1, 2-or 1, 3-propylene glycol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, glycerol and trimethylolpropane;

the polyester polyol B can also be more than one of polycaprolactone polyol and polycarbonate polyol.

The antioxidant is more than one of antioxidant 245, antioxidant 1035 and antioxidant 1076.

The side reaction inhibitor is phosphoric acid.

The number average molecular weight of the low molecular weight polyamide resin polyol is 700-2000, and the low molecular weight polyamide resin polyol is a reaction product of dibasic acid, diamine and alcohol amine.

The preparation method of the solvent-free polyurethane resin for the high-peeling foaming layer comprises the following steps:

(1) preparation of resin A component: mixing polyol A, low molecular weight polyamide resin polyol, a chain extender, a leveling agent and a defoaming agent at the temperature of 30-60 ℃ for 2-4 hours, measuring a hydroxyl value, adding a foaming agent after the hydroxyl value reaches the formula calculated amount, stirring for 0.5-1.0 hour, discharging, measuring the water content to be within +/-10% of the formula set amount, and sealing and storing to obtain a resin A component;

(2) preparation of resin B component: reacting aromatic isocyanate, polyol B, low molecular weight polyamide resin polyol, an antioxidant and a side reaction inhibitor for 2-3 hours at the temperature of 70-80 ℃ to form an isocyanate group-terminated prepolymer, then adding aliphatic isocyanate, discharging when the NCO content reaches the formula calculated amount relative to the total mass of the component B, sealing and storing to obtain the component B.

The solvent-free polyurethane resin for the high-peel foaming layer can be used for preparing solvent-free synthetic leather, and the application method comprises the following steps:

mixing the component A with a catalyst, standing to remove large stirring air bubbles, injecting the mixture into a tank A of a polyurethane low-pressure coating machine, adding the component B into a tank B of the polyurethane low-pressure coating machine, setting a storage tank A, B to be at the temperature of (20-40), mixing the component AB, coating and scraping the mixture on a water-based surface layer according to the thickness of (0.2-0.4) mm, baking the mixture at the temperature of (90-100) DEG C to be in a half-dry state, attaching the mixture to a substrate, baking the mixture at the temperature of (130-140) DEG C to be cured, taking out the cured product to be cooled to room temperature, and peeling off release paper to obtain the solvent-free synthetic leather.

The mass ratio of the catalyst to the polyol A in the component A is (1-2): 100.

The catalyst is a mixture of a delayed catalyst and a low-temperature thermosensitive catalyst; the mass ratio of the delayed catalyst to the low-temperature thermosensitive catalyst is 1: 2-2: 1; the delayed catalyst is organic bismuth and/or organic tin; the low-temperature heat-sensitive catalyst is a1, 8-diazabicycloundec-7-ene salt catalyst.

Compared with the prior art, the invention has the following beneficial effects:

(1) the low molecular weight polyamide resin polyol structure is successfully introduced into the solvent-free polyurethane resin, so that the polarity and the strength of a polyurethane system are improved, and the bonding strength between the solvent-free middle layer/foaming layer and the waterborne polyurethane surface layer is improved.

(2) The technology that polyamide resin polyol is used as a raw material to participate in reaction is adopted to improve the solvent-free polyurethane resin, and the low molecular weight polyamide resin polyol is in a hydroxyl end-capped structure, so that the reaction rate of the original solvent-free resin is not changed, and the stability of the production process of the synthetic leather production line is effectively ensured.

(3) The low molecular weight polyamide resin polyol can improve the hydrolysis resistance of the polyester type solvent-free polyurethane resin because the amido bond is not easy to hydrolyze,

(4) and (2) adding aromatic isocyanate and polyol into the component B to react at the temperature of 70-80 ℃ to form an NCO end-capping prepolymer, adding aliphatic isocyanate to enable the aliphatic isocyanate to be in a free state, and forming a chain extension reaction with carboxylic acid or sulfonic acid in the water-based surface layer when the component AB is mixed and scraped on the water-based surface layer, namely forming chemical bonding between the solvent-free foaming layer and the water-based surface layer, so that the stripping load is further improved.

(5) The addition of the low molecular weight polyamide resin polyol improves the heat resistance of the foaming layer made of the solvent-free resin.

Detailed Description

The present invention is further illustrated by the following specific examples, but it should be understood that the specific materials, process conditions and results described in the examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and all equivalent changes and modifications made according to the spirit of the present invention should be covered by the scope of the present invention.

In the examples, Puranol D220, Puranol D240 and Puranol D280 are ethylene oxide-propylene oxide co-polyether polyols, available from Ikeka chemical Co., Ltd;

ZSN-260 is ethylene oxide propylene oxide copolymerized polyether polyol, which is purchased from Jiangsu Bonshan chemical Co., Ltd; 330N is ethylene oxide-propylene oxide copolymerized polyether polyol which is a conventional raw material in the industry; JQD-380 is ethylene oxide propylene oxide copolymerized polyether polyol, purchased from Nanjing Jinxizu chemical group Co., Ltd; PE-8092, PE-7010, PE-3756 and PE-7720T were purchased from Zhejiang Huafeng New materials GmbH; BYK-3550, BYK-066N available from Pico Chemicals; valikat Bi 2010 from Umicore Youmei; SA102 is available from Meiji corporation, USA.

Example 1

(1) Preparation of resin A component: mixing polyether polyol, low molecular weight polyamide resin polyol, a chain extender, a leveling agent and a defoaming agent at 30 ℃ for 4 hours according to the following table 1, measuring a hydroxyl value, adding water after the hydroxyl value reaches 54.50mgKOH/g, stirring for 1.0 hour, discharging, and sealing and storing when the measured water content reaches 0.08-0.10 wt% to obtain a resin A component;

(2) preparation of resin B component: according to the table 1, aromatic isocyanate, polyether glycol and phosphoric acid react for 3 hours at the temperature of 70 ℃ to form isocyanate group-terminated prepolymer, then aliphatic isocyanate is added, and when the NCO content reaches 11.48 wt%, the mixture is discharged, sealed and stored to obtain the resin B component.

(3) Preparation of the solvent-free synthetic leather: mixing the component A with a catalyst according to the table 1, standing to remove large stirring air bubbles, injecting the mixture into a tank A of a polyurethane low-pressure coating machine, adding the component B into a tank B of the polyurethane low-pressure coating machine, setting a storage tank of A, B ℃ to be 20 ℃, mixing the component AB, scraping the mixture on a water-based surface layer according to the thickness of 0.3mm, baking the mixture at 90 ℃ to be in a semi-dry state, attaching the mixture to a substrate, baking the mixture at 140 ℃ to be cured, taking out the mixture to be cooled to room temperature, and peeling release paper to obtain the solvent-free synthetic leather.

Example 2

(1) Preparation of resin A component: mixing polyester polyol, low molecular weight polyamide resin polyol, a chain extender, a flatting agent and a defoaming agent at 60 ℃ for 2 hours, measuring a hydroxyl value, adding water after the hydroxyl value reaches 116.64mgKOH/g, stirring for 0.5 hour, discharging, and sealing and storing when the measured water content reaches 0.15-0.18 wt% to obtain a resin A component;

(2) preparation of resin B component: according to the table 1, aromatic isocyanate, polyester polyol, low molecular weight polyamide resin polyol, an antioxidant and phosphoric acid react for 2 hours at the temperature of 80 ℃ to form isocyanate group-terminated prepolymer, then aliphatic isocyanate is added, and when the NCO content reaches 13.85 wt%, discharging, sealing and storing are carried out to obtain the resin B component.

(3) Preparation of the solvent-free synthetic leather: mixing the component A with a catalyst according to the table 1, standing to remove large stirring air bubbles, injecting the mixture into a tank A of a polyurethane low-pressure coating machine, adding the component B into a tank B of the polyurethane low-pressure coating machine, setting a storage tank A, B to be 40 ℃, mixing the component AB, coating the mixture on a water-based surface layer according to the thickness of 0.3mm, baking the mixture at 100 ℃ to be in a semi-dry state, attaching the mixture to a substrate, baking the mixture at 130 ℃ to be cured, taking out the substrate, cooling the substrate to room temperature, and peeling release paper to obtain the solvent-free synthetic leather.

Example 3

(1) Preparation of resin A component: mixing polyether polyol, polyester polyol, low molecular weight polyamide resin polyol, a chain extender, a leveling agent and a defoaming agent at 45 ℃ for 3 hours, measuring a hydroxyl value, adding water after the hydroxyl value reaches 103.33mgKOH/g, stirring for 1.0 hour, discharging, and sealing and storing when the measured water content reaches 0.19-0.23 wt% to obtain a resin A component;

(2) preparation of resin B component: according to the table 1, aromatic isocyanate, polyether polyol, polyester polyol, low molecular weight polyamide resin polyol, an antioxidant and phosphoric acid react for 2 hours at the temperature of 80 ℃ to form isocyanate group-terminated prepolymer, then aliphatic isocyanate is added, and when the NCO content reaches 13.84 wt%, discharging, sealing and storing are carried out to obtain the resin B component.

(3) Preparation of the solvent-free synthetic leather: mixing the component A with a catalyst according to the table 1, standing to remove large stirring air bubbles, injecting the mixture into a tank A of a polyurethane low-pressure coating machine, adding the component B into a tank B of the polyurethane low-pressure coating machine, setting a storage tank A, B to be 30 ℃, mixing the component AB, coating the mixture on a water-based surface layer according to the thickness of 0.2mm, baking the mixture at 90 ℃ to be in a semi-dry state, attaching the mixture to a substrate, baking the mixture at 130 ℃ to be cured, taking out the substrate, cooling the substrate to room temperature, and peeling release paper to obtain the solvent-free synthetic leather.

Example 4

(1) Preparation of resin A component: mixing polyether polyol, polyester polyol, low molecular weight polyamide resin polyol, a chain extender, a leveling agent and a defoaming agent at 40 ℃ for 4 hours, measuring a hydroxyl value, adding water after the hydroxyl value reaches 98.57mgKOH/g, stirring for 0.8 hour, discharging, and sealing and storing when the measured water content reaches 0.17-0.21 wt% to obtain a resin A component;

(2) preparation of resin B component: according to the table 1, aromatic isocyanate, polyether polyol, polyester polyol, low molecular weight polyamide resin polyol, an antioxidant and phosphoric acid react for 2.5 hours at the temperature of 75 ℃ to form isocyanate group-terminated prepolymer, then aliphatic isocyanate is added, and when the NCO content reaches 15.02 wt%, the mixture is discharged, sealed and stored to obtain a resin B component.

(3) Preparation of the solvent-free synthetic leather: mixing the component A with a catalyst according to the table 1, standing to remove large stirring air bubbles, injecting the mixture into a tank A of a polyurethane low-pressure coating machine, adding the component B into a tank B of the polyurethane low-pressure coating machine, setting a storage tank A, B to be 40 ℃, mixing the component AB, coating the mixture on a water-based surface layer according to the thickness of 0.4mm, baking the mixture at 100 ℃ to be in a semi-dry state, attaching the mixture to a substrate, baking the mixture at 140 ℃ to be cured, taking out the substrate, cooling the substrate to room temperature, and peeling release paper to obtain the solvent-free synthetic leather.

Example 5

(1) Preparation of resin A component: mixing polyether polyol, polyester polyol, low molecular weight polyamide resin polyol, a chain extender, a leveling agent and a defoaming agent at 40 ℃ for 4 hours, measuring a hydroxyl value, adding water after the hydroxyl value reaches 97.63mgKOH/g, stirring for 0.8 hour, discharging, and sealing and storing when the measured water content reaches 0.17-0.21 wt% to obtain a resin A component;

(2) preparation of resin B component: according to the table 1, aromatic isocyanate, polyether polyol, polyester polyol, low molecular weight polyamide resin polyol, an antioxidant and phosphoric acid react for 2.5 hours at the temperature of 75 ℃ to form isocyanate group-terminated prepolymer, then aliphatic isocyanate is added, and when the NCO content reaches 17.36 wt%, the mixture is discharged, sealed and stored to obtain a resin B component.

(3) Preparation of the solvent-free synthetic leather: mixing the component A with a catalyst, standing to remove large stirring air bubbles, injecting into a tank A of a polyurethane low-pressure coating machine, adding the component B into a tank B of the polyurethane low-pressure coating machine, setting a storage tank A, B as 40 ℃, mixing the component AB, coating and scraping on a water-based surface layer according to the thickness of 0.4mm, baking at 100 ℃ to a semi-dry state, attaching to a base material, baking at 140 ℃ to solidify, taking out and cooling to room temperature, and peeling off release paper to obtain the solvent-free synthetic leather.

TABLE 1

Comparative example 1

(1) Preparation of resin A component: mixing polyether polyol, a chain extender, a leveling agent and a defoaming agent at 30 ℃ for 4 hours according to the table 2, measuring a hydroxyl value, adding water after the hydroxyl value reaches 53.25mgKOH/g, stirring for 1.0 hour, discharging, and sealing and storing when the measured water content reaches 0.09-0.11 wt% to obtain a resin A component;

(2) preparation of resin B component: according to the table 2, aromatic isocyanate, polyether glycol and phosphoric acid react for 3 hours at the temperature of 70 ℃ to form isocyanate group-terminated prepolymer, then aliphatic isocyanate is added, and when the NCO content reaches 11.48 wt%, the mixture is discharged, sealed and stored to obtain the resin B component.

(3) Preparation of the solvent-free synthetic leather: mixing the component A with a catalyst according to the table 2, standing to remove large stirring air bubbles, injecting the mixture into a tank A of a polyurethane low-pressure coating machine, adding the component B into a tank B of the polyurethane low-pressure coating machine, setting a storage tank of A, B ℃ to be 20 ℃, mixing the component AB, scraping the mixture on a water-based surface layer according to the thickness of 0.3mm, baking the mixture at 90 ℃ to be in a semi-dry state, attaching the mixture to a substrate, baking the mixture at 140 ℃ to be cured, taking out the mixture to be cooled to room temperature, and peeling release paper to obtain the solvent-free synthetic leather.

Comparative example 2

(1) Preparation of resin A component: mixing polyester polyol, a chain extender, a leveling agent and a defoaming agent at 60 ℃ for 2 hours according to the table 2, measuring a hydroxyl value, adding water after the hydroxyl value reaches 120.35mgKOH/g, stirring for 0.5 hour, discharging, and sealing and storing when the measured water content reaches 0.17-0.21 wt% to obtain a resin A component;

(2) preparation of resin B component: according to the table 2, aromatic isocyanate, polyester polyol, antioxidant and phosphoric acid react for 2 hours at the temperature of 80 ℃ to form isocyanate group-terminated prepolymer, then aliphatic isocyanate is added, and when the NCO content reaches 17.87 wt%, discharging, sealing and storing are carried out to obtain the resin B component.

(3) Preparation of the solvent-free synthetic leather: mixing the component A with a catalyst according to the table 2, standing to remove large stirring air bubbles, injecting the mixture into a tank A of a polyurethane low-pressure coating machine, adding the component B into a tank B of the polyurethane low-pressure coating machine, setting a storage tank A, B to be 40 ℃, mixing the component AB, scraping the mixture on a water-based surface layer according to the thickness of 0.3mm, baking the mixture at 100 ℃ to be in a semi-dry state, attaching the mixture to a substrate, baking the mixture at 130 ℃ to be cured, taking out the substrate, cooling the substrate to room temperature, and peeling release paper to obtain the solvent-free synthetic leather.

Comparative example 3

(1) Preparation of resin A component: mixing polyether polyol, polyester polyol, a chain extender, a flatting agent and a defoaming agent at 45 ℃ for 3 hours according to the table 2, measuring a hydroxyl value, adding water after the hydroxyl value reaches 109.44mgKOH/g, stirring for 1.0 hour, discharging, and sealing and storing when the measured moisture content reaches 0.25-0.30 wt% to obtain a resin A component;

(2) preparation of resin B component: according to the table 2, aromatic isocyanate, aliphatic isocyanate, polyether polyol, polyester polyol, an antioxidant and phosphoric acid are reacted for 2 hours at the temperature of 80 ℃, and when the NCO content reaches 14.89 wt%, the materials are discharged, sealed and stored, so that the resin B component is obtained.

(3) Preparation of the solvent-free synthetic leather: mixing the component A with a catalyst according to the table 2, standing to remove large stirring air bubbles, injecting the mixture into a tank A of a polyurethane low-pressure coating machine, adding the component B into a tank B of the polyurethane low-pressure coating machine, setting a storage tank A, B to be 30 ℃, mixing the component AB, scraping the mixture on a water-based surface layer according to the thickness of 0.2mm, baking the mixture at 90 ℃ to be in a semi-dry state, attaching the mixture to a substrate, baking the mixture at 130 ℃ to be cured, taking out the mixture to be cooled to room temperature, and peeling release paper to obtain the solvent-free synthetic leather.

Comparative example 4

(1) Preparation of resin A component: mixing polyether polyol, polyester polyol, a chain extender, a flatting agent and a defoaming agent at 40 ℃ for 4 hours according to the table 2, measuring a hydroxyl value, adding water after the hydroxyl value reaches 118.13mgKOH/g, stirring for 0.8 hour, discharging, and sealing and storing when the measured moisture content reaches 0.24-0.30 wt% to obtain a resin A component;

(2) preparation of resin B component: according to the table 2, aromatic isocyanate, polyether polyol, polyester polyol, an antioxidant and phosphoric acid react for 2.5 hours at the temperature of 75 ℃ to form isocyanate group-terminated prepolymer, then aliphatic isocyanate is added, and when the NCO content reaches 15.35 wt%, the mixture is discharged, sealed and stored to obtain the resin B component.

(3) Preparation of the solvent-free synthetic leather: mixing the component A with a catalyst according to the table 2, standing to remove large stirring air bubbles, injecting the mixture into a tank A of a polyurethane low-pressure coating machine, adding the component B into a tank B of the polyurethane low-pressure coating machine, setting a storage tank A, B to be 40 ℃, mixing the component AB, scraping the mixture on a water-based surface layer according to the thickness of 0.4mm, baking the mixture at 100 ℃ to be in a semi-dry state, attaching the mixture to a substrate, baking the mixture at 140 ℃ to be cured, taking out the substrate, cooling the substrate to room temperature, and peeling release paper to obtain the solvent-free synthetic leather.

Comparative example 5

(1) Preparation of resin A component: mixing polyether polyol, polyester polyol, a chain extender, a flatting agent and a defoaming agent at 40 ℃ for 4 hours according to the table 2, measuring a hydroxyl value, adding water after the hydroxyl value reaches 116.75mgKOH/g, stirring for 0.8 hour, discharging, and sealing and storing when the measured moisture content reaches 0.24-0.30 wt% to obtain a resin A component;

(2) preparation of resin B component: according to the table 2, aromatic isocyanate, aliphatic isocyanate, polyether polyol, polyester polyol, an antioxidant and phosphoric acid are reacted for 2.5 hours at the temperature of 75 ℃, and when the NCO content reaches 17.38 wt%, the materials are discharged, sealed and stored, so that the resin B component is obtained.

(3) Preparation of the solvent-free synthetic leather: mixing the component A with a catalyst according to the table 2, standing to remove large stirring air bubbles, injecting the mixture into a tank A of a polyurethane low-pressure coating machine, adding the component B into a tank B of the polyurethane low-pressure coating machine, setting a storage tank A, B to be 40 ℃, mixing the component AB, scraping the mixture on a water-based surface layer according to the thickness of 0.4mm, baking the mixture at 100 ℃ to be in a semi-dry state, attaching the mixture to a substrate, baking the mixture at 140 ℃ to be cured, taking out the substrate, cooling the substrate to room temperature, and peeling release paper to obtain the solvent-free synthetic leather.

TABLE 2

The results of the physical property tests of the solvent-free synthetic leathers prepared in application examples 1 to 5 and comparative examples 1 to 5 are shown in Table 3.

TABLE 3

The initial peel load test is that the sample is cut immediately after the preparation of the solvent-free synthetic leather is finished, and the peel load after curing is that the sample is cured for 24 hours at room temperature after the preparation of the solvent-free synthetic leather is finished and then the measurement is carried out. Hydrolysis resistance was tested according to QB/T4671-. As is clear from Table 3, in the present invention, the addition of the low molecular weight polyamide resin polyol to the solventless foamed leather resin improves the peeling load between the solventless foamed layer and the aqueous top layer, and improves the hydrolysis resistance and the heat resistance. Aromatic isocyanate and aliphatic isocyanate are used in the component B of the solvent-free foaming leather resin, the aromatic isocyanate and polyether polyol form NCO end-capping prepolymer, and when the aliphatic isocyanate is in a free state and is mixed with the component A and then is coated on the water-based surface layer, the stripping load of the formed foaming layer and the water-based surface layer is higher.

Although the embodiments of the present invention have been described in detail, the technical aspects of the present invention are not limited to the embodiments, and equivalent changes or modifications made to the contents of the claims of the present invention should fall within the technical scope of the present invention without departing from the spirit and the spirit of the present invention.

Claims (14)

1. The solvent-free polyurethane resin for the high-stripping foaming layer is characterized by comprising a resin A component and a resin B component, wherein the resin A component contains low-molecular-weight polyamide resin polyol, the resin B component contains isocyanate, the isocyanate is a mixture of aromatic isocyanate and aliphatic isocyanate, and the ratio of the mole number of active hydrogen in the resin A component to the mole number of isocyanate groups in the resin B component is 0.95: 1-1: 1.05;

the resin A component comprises the following components in parts by mass:

100 portions of polyol A

5-50 parts of low molecular weight polyamide resin polyol

2-8 parts of chain extender

0.1-0.3 part of flatting agent

0.1-0.3 part of foaming agent

0.1-0.3 part of defoaming agent;

the resin B component comprises the following components in parts by mass:

30-60 parts of isocyanate;

40-70 parts of polyol B;

0-20 parts of low molecular weight polyamide resin polyol, wherein the content of the low molecular weight polyamide resin polyol is not 0;

the number average molecular weight of the low molecular weight polyamide resin polyol is 700-2000, and the low molecular weight polyamide resin polyol is a reaction product of dibasic acid, diamine and alcohol amine;

the preparation method of the solvent-free polyurethane resin for the high-stripping foaming layer comprises the following steps:

the preparation steps of the resin A component are as follows: mixing the polyol A, the low molecular weight polyamide resin polyol, the chain extender, the flatting agent and the defoaming agent, measuring a hydroxyl value, adding the foaming agent after the hydroxyl value reaches the formula calculated amount, stirring and discharging, measuring the moisture content to be within +/-10% of the formula set amount, and sealing and storing to obtain a resin A component;

the preparation steps of the resin B component are as follows: reacting aromatic isocyanate, polyol B, low molecular weight polyamide resin polyol, an antioxidant and a side reaction inhibitor to form an isocyanate group-terminated prepolymer, adding aliphatic isocyanate, discharging when the NCO content reaches the formula calculated amount relative to the total mass of the component B, and sealing and storing to obtain the component B.

2. The solvent-free polyurethane resin for a high-release foam layer according to claim 1, wherein the polyol a is a polyester polyol a and/or a polyether polyol a; the polyether polyol A has a functionality of 2-3 and a hydroxyl value of 12.5-58.0 mgKOH/g.

3. The solvent-free polyurethane resin for a high-release foam layer according to claim 2, wherein the polyether polyol a is obtained by polymerizing ethylene oxide and/or propylene oxide with at least one of ethylene glycol, diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, ethanolamine, diethanolamine, and triethanolamine as an initiator;

the polyester polyol A is prepared by esterification reaction of organic dicarboxylic acid containing 4-10 carbon atoms and micromolecular polyol containing 2-6 carbon atoms; a functionality of 2 to 3 and a hydroxyl value of 54 to 114 mgKOH/g.

4. The solvent-free polyurethane resin for a high-release foam layer according to claim 3, wherein the small-molecular polyol is one or more of ethylene glycol, diethylene glycol, 1, 2-or 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, glycerin, and trimethylolpropane; the organic dicarboxylic acid is more than one of adipic acid, succinic acid, glutaric acid, suberic acid, sebacic acid, azelaic acid, phthalic acid, terephthalic acid, isophthalic acid, decanedicarboxylic acid and maleic acid.

5. The solvent-free polyurethane resin for a high-release foam layer according to claim 3, wherein the polyester polyol A is one or more of polycaprolactone polyol and polycarbonate polyol.

6. The solvent-free polyurethane resin for a high-release foam layer according to claim 2, wherein the polyether polyol A is a mixture of 2-functionality and 3-functionality polyether polyols A, and the mass ratio of the 2-functionality to the 3-functionality polyether polyols is 4:6 to 7: 3.

7. The solvent-free polyurethane resin for a high-release foam layer according to claim 1, wherein the chain extender is one or more of ethylene glycol, diethylene glycol, 1, 4-butanediol, 1, 6-hexanediol, 1, 3-propanediol, and 3-methyl-1, 5-pentanediol; the leveling agent is modified polysiloxane, the foaming agent is water, and the defoaming agent is polyether modified siloxane.

8. The solvent-free polyurethane resin for a high-release foam layer according to claim 1, wherein the polyol B is polyether polyol B and/or polyester polyol B;

the polyether polyol B is prepared by polymerizing more than one of ethylene glycol, diethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, ethanolamine, diethanolamine and triethanolamine with ethylene oxide and/or propylene oxide as an initiator; a functionality of 2 to 3 and a hydroxyl value of 12.5 to 58.0 mgKOH/g;

the polyester polyol B is prepared by esterification and polymerization reaction of organic dicarboxylic acid containing 4-10 carbon atoms and micromolecular polyol containing 2-6 carbon atoms, the hydroxyl value is 54-114 mgKOH/g, and the functionality is 2-3.

9. The solvent-free polyurethane resin for a high-release foam layer according to claim 8, wherein the organic dicarboxylic acid is one or more selected from adipic acid, succinic acid, glutaric acid, suberic acid, sebacic acid, azelaic acid, phthalic acid, terephthalic acid, isophthalic acid, decanedicarboxylic acid, and maleic acid; the small molecular polyol is more than one of ethylene glycol, diethylene glycol, 1, 2-or 1, 3-propylene glycol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, glycerol and trimethylolpropane.

10. The solvent-free polyurethane resin for a high-release foam layer according to claim 9, wherein the polyester polyol B is one or more of polycaprolactone polyol and polycarbonate polyol.

11. The solvent-free polyurethane resin for a high-release foam layer according to claim 1, wherein the resin B component further comprises an antioxidant and a side reaction inhibitor, the antioxidant accounts for 0-0.10 wt% of the total mass of the resin B component, the side reaction inhibitor accounts for 30-100 ppm of the total mass of the resin B component, and the side reaction inhibitor is phosphoric acid.

12. The solvent-free polyurethane resin for a high-release foamed layer according to claim 1, wherein the isocyanate is a mixture of an aromatic isocyanate and an aliphatic isocyanate, and the mass ratio of the aromatic isocyanate to the aliphatic isocyanate is 7:1 to 30: 1;

the aromatic isocyanate is more than one of diphenylmethane diisocyanate, toluene diisocyanate, p-phenylene diisocyanate, naphthalene diisocyanate and polymethylene polyphenyl isocyanate;

the aliphatic isocyanate is more than one of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexyl methane diisocyanate and cyclohexane dimethylene diisocyanate.

13. Use of the solvent-free polyurethane resin for a high-peel foam layer according to any one of claims 1 to 12, for preparing solvent-free synthetic leather.

14. Use according to claim 13, characterized in that the method of application comprises the following steps:

mixing the component A with a catalyst, standing to remove large stirring air bubbles, injecting the mixture into a tank A of a polyurethane low-pressure coating machine, adding the component B into a tank B of the polyurethane low-pressure coating machine, setting an A, B storage tank at 20-40 ℃, mixing the component AB, coating and scraping the mixture on a water-based surface layer according to the thickness of (0.2-0.4) mm, (baking at 90-100) DEG C to a semi-dry state, attaching to a substrate, baking at 130-140℃ to cure, taking out and cooling to room temperature, and peeling release paper to obtain the solvent-free synthetic leather; the mass ratio of the catalyst to the polyol A in the component A is (1-2) to 100;

the catalyst is a mixture of a delayed catalyst and a low-temperature thermosensitive catalyst; the mass ratio of the delayed catalyst to the low-temperature thermosensitive catalyst is 1: 2-2: 1; the delayed catalyst is organic bismuth and/or organic tin; the low-temperature heat-sensitive catalyst is a1, 8-diazabicycloundec-7-ene salt catalyst.