Polyurethane adhesive as well as preparation method and application thereof

Abstract

The invention discloses a polyurethane adhesive and a preparation method and application thereof.The polyurethane adhesive comprises a main adhesive and a curing agent, raw materials of the main adhesive comprise polyhydric alcohols and polyisocyanate, the polyurethane adhesive is prepared by compounding three specific polyhydric alcohols to serve as the polyhydric alcohols, and the adhesive is endowed with excellent initial adhesion, high temperature resistance, hydrolysis resistance and other performance; the adhesive can realize rapid bonding and shaping, does not debond in the carpet printing process, and can be applied to cloth-cloth compounding, such as carpet compounding and wall cloth compounding.

Description

Technical Field

[0001] The invention relates to the field of polyurethane adhesives, and in particular to a polyurethane adhesive and a preparation method and application thereof. Background Art

[0002] In the textile industry, cloth-to-cloth lamination is a common lamination process, and polyurethane adhesives are widely used. Currently, polyurethane adhesives are divided into solvent-based and solvent-free types; among them, solvent-based two-component polyurethane adhesives are the products with the most varieties, the largest usage, and the widest application. Ordinary cloth-to-cloth lamination does not require high performance from adhesives, and basically all performance requirements can be met. However, in some cloth-to-cloth lamination processes with special requirements, such as wall cloth lamination and carpet lamination, there is a need for high temperature resistance and no debonding, and good initial adhesion is required to achieve rapid bonding and fixing. The performance requirements for adhesives are high, and ordinary adhesives cannot meet such requirements.

[0003] For example, CN114539967B discloses a polyurethane adhesive main glue for wall cloth composite and its preparation method and polyurethane adhesive. The raw material formula of the main glue includes the following components by weight percentage: polyester polyol A 20-40%, polyester polyol B 25-45%, antioxidant 0.01-0.1%, chain extender 0.05-0.1%, cross-linking agent 0.01-0.15%, first solvent 20-35%, isocyanate 3-10%, catalyst 0.001-0.01%, terminator 0.01-0.1%; polyester polyol A is a polyester polyol prepared by polymerizing dibasic acid A and diol A, dibasic acid A includes a combination of one or more of terephthalic acid, phthalic anhydride, and isophthalic acid, and diol A includes ethylene glycol and diethylene glycol, propylene glycol, butanediol, The polyester polyol B is prepared by polymerizing dibasic acid B and diol B, wherein dibasic acid B includes one or more of terephthalic acid, phthalic anhydride, isophthalic acid and one or more of adipic acid, sebacic acid, and succinic acid, and diol B includes one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, and neopentyl glycol, and the molar ratio of ethylene glycol to diol B is 0.3 to 0.4: 1. Although the patent has achieved a certain initial adhesion and can withstand 80°C water washing, it still needs to be improved.

[0004] It should be noted that the information disclosed in the above background technology section is only used to understand the background of the present application, so the background technology section of the present invention may contain background information about the problem or environment of the present invention, but not necessarily describe the prior art. Therefore, the content contained in the background technology section is not an admission of the applicant to the prior art. Summary of the invention

[0005] The object of the present invention is to overcome one or more deficiencies in the prior art and to provide an improved polyurethane adhesive having good initial adhesion, high temperature resistance, hydrolysis resistance and the like.

[0006] The present invention also provides a method for preparing the polyurethane adhesive and its application in cloth-to-cloth lamination, such as carpet lamination and wall cloth lamination.

[0007] In order to achieve the above object, a technical solution adopted by the present invention is:

[0008] A polyurethane adhesive comprises a main adhesive and a curing agent, wherein the raw materials of the main adhesive comprise polyols and polyisocyanates, the polyols comprise a first polyol, a second polyol and a third polyol, the total addition amount of the first polyol and the second polyol and the feeding mass ratio of the third polyol are 1:0.10-0.35, and the feeding mass ratio of the first polyol to the second polyol is 1:0.3-0.75;

[0009] The first polyol is prepared by reacting phthalic anhydride, trimellitic anhydride, diethylene glycol and methyl propylene glycol;

[0010] The second polyol is prepared by reacting terephthalic acid, phthalic anhydride, diethylene glycol, neopentyl glycol and ethylene glycol;

[0011] The third polyol is prepared by reacting modified vegetable oil and alkylene oxide, wherein the modified vegetable oil is prepared by reacting vegetable oil containing hydroxyl group and propylene glycol.

[0012] Another technical solution provided by the present invention is a main glue for polyurethane adhesive, wherein the raw materials include polyols and polyisocyanates, wherein the polyols include a first polyol, a second polyol and a third polyol, wherein the total addition amount of the first polyol and the second polyol and the feeding mass ratio of the third polyol are 1:0.10-0.35, and the feeding mass ratio of the first polyol to the second polyol is 1:0.3-0.75;

[0013] The first polyol is prepared by reacting phthalic anhydride, trimellitic anhydride, diethylene glycol and methyl propylene glycol;

[0014] The second polyol is prepared by reacting terephthalic acid, phthalic anhydride, diethylene glycol, neopentyl glycol and ethylene glycol;

[0015] The third polyol is prepared by reacting modified vegetable oil and alkylene oxide, wherein the modified vegetable oil is prepared by reacting vegetable oil containing hydroxyl group and propylene glycol.

[0016] In some embodiments of the present invention, the number average molecular weight of the first polyol is 2500-4500. According to some specific aspects of the present invention, the number average molecular weight of the first polyol is 2500-3000.

[0017] In some embodiments of the present invention, the number average molecular weight of the second polyol is 2500-3000. According to some specific aspects of the present invention, the number average molecular weight of the second polyol is 2500-2800.

[0018] In some embodiments of the present invention, the number average molecular weight of the third polyol is 2000-3000. According to some specific aspects of the present invention, the number average molecular weight of the third polyol is 2000-2500.

[0019] In some embodiments of the present invention, in the first polyol, the molar ratio of the total amount of the phthalic anhydride and the trimellitic anhydride to the total amount of the diethylene glycol and the methyl propylene glycol is 1:1.02-1.15. Further, in the first polyol, the molar ratio of the total amount of the phthalic anhydride and the trimellitic anhydride to the total amount of the diethylene glycol and the methyl propylene glycol is 1:1.02-1.13. According to a specific aspect of the present invention, in the first polyol, the molar ratio of the total amount of the phthalic anhydride and the trimellitic anhydride to the total amount of the diethylene glycol and the methyl propylene glycol is 1:1.03-1.1.

[0020] In some embodiments of the present invention, in the first polyol, the molar ratio of the phthalic anhydride to the trimellitic anhydride is 1:0.1-0.25; further, the molar ratio of the phthalic anhydride to the trimellitic anhydride is 1:0.1-0.2.

[0021] In some embodiments of the present invention, in the first polyol, the molar ratio of the diethylene glycol to the methyl propylene glycol is 1:0.3-0.6; further, the molar ratio of the diethylene glycol to the methyl propylene glycol is 1:0.4-0.55.

[0022] In some embodiments of the present invention, the preparation method of the first polyol includes: adding a certain mass of phthalic anhydride, trimellitic anhydride, diethylene glycol, and methyl propylene glycol to a reaction kettle, heating to 175-185°C, and gradually discharging the water generated by the reaction after the reaction, and heating by 1-10°C every 5-15 minutes, gradually heating to 215-235°C; sampling and testing the acid value and hydroxyl value every hour. Further, when the acid value is about ≤0.5mgKOH / g and the hydroxyl value is about 44.5-46mgKOH / g, the temperature is lowered.

[0023] In some embodiments of the present invention, in the second polyol, the molar ratio between the total amount of the terephthalic acid and the phthalic anhydride added and the total amount of the diethylene glycol, the neopentyl glycol and the ethylene glycol added is 1:1.02-1.15. Further, in the second polyol, the molar ratio between the total amount of the terephthalic acid and the phthalic anhydride added and the total amount of the diethylene glycol, the neopentyl glycol and the ethylene glycol added is 1:1.02-1.13. According to a specific aspect of the present invention, in the second polyol, the molar ratio between the total amount of the terephthalic acid and the phthalic anhydride added and the total amount of the diethylene glycol, the neopentyl glycol and the ethylene glycol added is 1:1.02-1.1.

[0024] In some embodiments of the present invention, in the second polyol, the molar ratio of the terephthalic acid to the phthalic anhydride is 1:1.5-2.5. Furthermore, in the second polyol, the molar ratio of the terephthalic acid to the phthalic anhydride is 1:1.8-2.2.

[0025] In some embodiments of the present invention, in the second polyol, the molar ratio of the diethylene glycol, the neopentyl glycol and the ethylene glycol is 1: 0.35-0.55: 0.8-1.2. Further, in the second polyol, the molar ratio of the diethylene glycol, the neopentyl glycol and the ethylene glycol is 1: 0.35-0.55: 0.9-1.1.

[0026] In some embodiments of the present invention, the preparation method of the second polyol includes: adding a certain mass of terephthalic acid, phthalic anhydride, diethylene glycol, neopentyl glycol, and ethylene glycol into a reactor, heating to 175-185°C, and gradually discharging the water generated by the reaction after the reaction, heating by 1-10°C every 5-15 minutes, and gradually heating to 215-235°C; sampling and testing the acid value and hydroxyl value every hour. Further, when the acid value is about 0.25-0.45 mgKOH / g and the hydroxyl value is about 45-47 mgKOH / g, the temperature is lowered.

[0027] In some embodiments of the present invention, the raw materials of the third polyol include hydroxyl-containing vegetable oil, propylene glycol and / or ethylene glycol, alkylene oxide, and alkali metal hydroxide, and the alkali metal hydroxide includes sodium hydroxide and / or potassium hydroxide.

[0028] In some embodiments of the present invention, the vegetable oil containing hydroxyl groups includes castor oil. The added amount of the castor oil accounts for 25%-40% of the raw material of the third polyol in terms of mass percentage.

[0029] In some embodiments of the present invention, the alkylene oxide is ethylene oxide and / or propylene oxide, and the added amount of the alkylene oxide accounts for 50%-65% of the raw material of the third polyol in terms of mass percentage.

[0030] In some embodiments of the present invention, the added amount of the propylene glycol and / or ethylene glycol accounts for 5%-15% of the raw material of the third polyol in terms of mass percentage.

[0031] In some embodiments of the present invention, the preparation method of the third polyol includes: mixing a vegetable oil containing a hydroxyl group, propylene glycol and / or ethylene glycol, and an alkali metal hydroxide, and then adding an alkylene oxide under a protective atmosphere at 100-130° C. and 0.1-0.4 MPa to react; adding phosphoric acid to neutralize the alkali metal hydroxide, filtering out the salt produced by the neutralization, and performing reduced pressure distillation to remove unreacted alkylene oxide and a small amount of low molecular weight polyether polyol product to obtain the third polyol.

[0032] Furthermore, the protective atmosphere is formed by introducing nitrogen and an inert gas, and the inert gas includes but is not limited to helium, argon, and the like.

[0033] In some embodiments of the present invention, the raw materials of the main rubber further include an antioxidant, a chain extender, a cross-linking agent, a solvent, a catalyst and a terminator;

[0034] Calculated by mass percentage, the raw materials of the main glue include: 40%-75% of polyol, 0.01%-0.5% of antioxidant, 0.05%-0.5% of chain extender, 0.01%-0.3% of cross-linking agent, 20%-50% of first solvent, 3%-10% of polyisocyanate, 0.001%-0.1% of catalyst and 0.01%-0.2% of terminator.

[0035] Furthermore, the polyisocyanate is toluene diisocyanate (TDI) and / or diphenylmethane diisocyanate (MDI).

[0036] Furthermore, the antioxidant is antioxidant 1010.

[0037] Furthermore, the chain extender includes 1,4-butanediol.

[0038] Furthermore, the cross-linking agent includes glycerol.

[0039] Furthermore, the first solvent includes dimethyl carbonate and / or N,N-dimethylformamide.

[0040] Furthermore, the catalyst includes an organic bismuth catalyst, and the organic bismuth catalyst may be bismuth 2010 or the like.

[0041] Furthermore, the terminator includes 1,3-butanediol.

[0042] In some embodiments of the present invention, the polyurethane adhesive further comprises a second solvent, and the mass ratio of the main adhesive, the curing agent and the second solvent is 10:0.8-1.5:2.5-5.

[0043] Furthermore, the second solvent includes but is not limited to methyl ester.

[0044] Furthermore, the curing agent includes but is not limited to Wanhua 9068.

[0045] Another technical solution provided by the present invention is a method for preparing the polyurethane adhesive described above, the preparation method comprising:

[0046] The first polyol, the second polyol, the third polyol, the antioxidant, the chain extender, the crosslinking agent and a part of the solvent are stirred and mixed at 50-60° C., and then polyisocyanate is added, the temperature is raised to 70-80° C., the reaction is stirred, a catalyst is added, the temperature is raised to 80-85° C., the reaction is continued, and after the viscosity reaches the standard, the heating is stopped, the terminator and the remaining solvent are added, the mixture is stirred, and the material is discharged to obtain the polyurethane adhesive.

[0047] Furthermore, the part of the solvent accounts for more than 50% of the total amount of the solvent, and further 50%-80%.

[0048] Furthermore, the viscosity that meets the standard is 200000-300000 mPa.s.

[0049] Another technical solution provided by the present invention is an application of the above-mentioned polyurethane adhesive as a binder in cloth-to-cloth lamination.

[0050] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0051] Based on the defects of existing polyurethane adhesives used for cloth-to-cloth lamination, such as insufficient temperature resistance, initial adhesion and flexibility, the present invention innovatively provides an improved polyurethane adhesive. The polyurethane adhesive is compounded with three specific polyols as polyols, which gives the adhesive excellent initial adhesion, high temperature resistance and hydrolysis resistance, can achieve rapid bonding and shaping, and can avoid debonding during the carpet printing process, and still has excellent peel strength after being placed in a high temperature and high humidity environment. DETAILED DESCRIPTION

[0052] The above scheme is further described below in conjunction with specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments; the implementation conditions adopted in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0053] Unless otherwise specified in the following examples, all raw materials are commercially available or prepared by conventional methods in the art.

[0054] Castor oil was purchased from Tonghua Castor Chemical; methyl ester was purchased from Shandong Baien New Materials; and the curing agent was Wanhua 9068.

[0055] Example 1

[0056] This example provides a polyurethane adhesive and a preparation method thereof. The polyurethane adhesive includes a main adhesive, a curing agent and methyl ester. The mass ratio of the main adhesive, the curing agent and the methyl ester is 10:1.2:3.5.

[0057] The formula content of the main glue is shown in Table 1.

[0058] Table 1

[0059]

[0060]

[0061] The preparation method of the main glue includes: adding 38 parts of the first polyol with a number average molecular weight of 2500, 12 parts of the second polyol with a number average molecular weight of 2500, 10 parts of the third polyol with a number average molecular weight of 2000, 0.1 parts of antioxidant 1010, 0.1 parts of 1,4-butanediol, and 0.05 parts of glycerol to a reactor, starting stirring, cooling to 55°C, adding 20 parts of dimethyl carbonate and 3 parts of DMF, stirring for 30 minutes, ensuring that the raw materials in the reactor are completely stirred, keeping the temperature of the reactor at 55°C, adding 5 parts of TDI and 1 part of MDI. Heating to 75°C and stirring for 1 hour. Adding 0.002 parts of an organic bismuth catalyst, heating to 80°C and continuing the reaction. When the viscosity reaches 250000 mPa.s at 80°C, turn off the heating, add 12 parts of dimethyl carbonate and 0.1 parts of 1,3-BG, stir for 1 hour, package and discharge the material to obtain the main glue, and seal and store;

[0062] The first polyol is prepared by the following method: 20 parts of phthalic anhydride, 4 parts of trimellitic anhydride, 12 parts of diethylene glycol, and 5 parts of methyl propylene glycol are added into a reaction kettle, the temperature is raised to 180°C, and after the water is produced by the reaction, the water produced by the reaction is gradually discharged, and the temperature is raised by 5°C every 10 minutes until the temperature is gradually raised to 225°C; when the acid value of the sample is 0.42 mgKOH / g and the hydroxyl value is 45.1 mgKOH / g, the temperature is lowered to obtain a first polyol with a number average molecular weight of about 2500;

[0063] The second polyol is prepared by the following method: 10 parts of terephthalic acid, 19 parts of phthalic anhydride, 9 parts of diethylene glycol, 4 parts of neopentyl glycol, and 5 parts of ethylene glycol are added into a reaction kettle, the temperature is raised to 180° C., after water is produced by the reaction, the water produced by the reaction is gradually discharged, the temperature is raised by 5° C. every 10 minutes, and the temperature is gradually raised to 230° C.; when the acid value of the sample is 0.32 mgKOH / g and the hydroxyl value is 46 mgKOH / g, the temperature is lowered to obtain a second polyol with a number average molecular weight of about 2500;

[0064] The third polyol is prepared by the following method: 30 parts of vegetable oil containing hydroxyl groups, 10 parts of propylene glycol and 3 parts of alkali metal hydroxide are mixed, and then 57 parts of alkylene oxide are added under a protective atmosphere, at 120°C and 0.2MPa, and the reaction is carried out for 5 hours; an appropriate amount of phosphoric acid is added to neutralize the alkali metal hydroxide, and the salt produced by the neutralization is filtered out; and then reduced pressure distillation is performed to remove unreacted alkylene oxide and a small amount of low molecular weight polyether polyol product to obtain the third polyol having a hydroxyl value of 56.3 mgKOH / g and a number average molecular weight of 2000.

[0065] The preparation method of the polyurethane adhesive comprises: preparing the main adhesive, the curing agent and the solvent (methyl ester) in proportion, and stirring them evenly to obtain the adhesive.

[0066] Example 2

[0067] This example provides a polyurethane adhesive and a preparation method thereof. The polyurethane adhesive includes a main adhesive, a curing agent and methyl ester. The mass ratio of the main adhesive, the curing agent and the methyl ester is 10:1.2:3.5.

[0068] The formula content of the main glue is shown in Table 2.

[0069] Table 2

[0070]

[0071] The preparation method of the main glue includes: adding 32 parts of the first polyol with a number average molecular weight of 2500, 15 parts of the second polyol with a number average molecular weight of 2500, 13 parts of the third polyol with a number average molecular weight of 2000, 0.1 parts of antioxidant 1010, 0.1 parts of 1,4-butanediol, and 0.1 parts of glycerol to a reactor, starting stirring, cooling to 55°C, adding 15 parts of dimethyl carbonate and 3 parts of DMF, stirring for 30 minutes, ensuring that the raw materials in the reactor are completely stirred, keeping the temperature of the reactor at 55°C, adding 4.5 parts of TDI and 1 part of MDI. Heating to 75°C and stirring for 1 hour. Adding 0.002 parts of an organic bismuth catalyst, heating to 80°C and continuing the reaction. When the viscosity reaches 240000 mPa.s at 80°C, turn off the heating, add 14 parts of dimethyl carbonate and 0.1 parts of 1,3-BG, stir for 1 hour, package and discharge the material to obtain the main glue, and seal and store;

[0072] Wherein, the first polyol, the second polyol and the third polyol are the same as those in Example 1.

[0073] The preparation method of the polyurethane adhesive comprises: preparing the main adhesive, the curing agent and the solvent (methyl ester) in proportion, and stirring them evenly to obtain the adhesive.

[0074] Example 3

[0075] This example provides a polyurethane adhesive and a preparation method thereof. The polyurethane adhesive includes a main adhesive, a curing agent and methyl ester. The mass ratio of the main adhesive, the curing agent and the methyl ester is 10:1.2:3.5.

[0076] The formula content of the main glue is shown in Table 3.

[0077] Table 3

[0078]

[0079] The preparation method of the main glue includes: adding 28 parts of the first polyol with a number average molecular weight of 2500, 20 parts of the second polyol with a number average molecular weight of 2500, 12 parts of the third polyol with a number average molecular weight of 2000, 0.1 parts of antioxidant 1010, 0.1 parts of 1,4-butanediol, and 0.15 parts of glycerol to the reactor, starting stirring, cooling to 55°C, adding 15 parts of dimethyl carbonate and 3 parts of DMF, stirring for 30 minutes, ensuring that the raw materials in the reactor are completely stirred, keeping the temperature of the reactor at 55°C, adding 4 parts of TDI and 1 part of MDI. Heating to 75°C and stirring for 1 hour. Adding 0.002 parts of organic bismuth catalyst, heating to 80°C and continuing the reaction. After the viscosity reaches 260000 mPa.s at 80°C, turn off the heating, add 13 parts of dimethyl carbonate and 0.1 parts of 1,3-BG, stir for 1 hour, package and discharge the material to obtain the main glue, and seal and store;

[0080] Wherein, the first polyol, the second polyol and the third polyol are the same as those in Example 1.

[0081] The preparation method of the polyurethane adhesive comprises: preparing the main adhesive, the curing agent and the solvent (methyl ester) in proportion, and stirring them evenly to obtain the adhesive.

[0082] Example 4

[0083] This example provides a polyurethane adhesive and a preparation method thereof. The polyurethane adhesive includes a main adhesive, a curing agent and methyl ester. The mass ratio of the main adhesive, the curing agent and the methyl ester is 10:1.2:3.5.

[0084] The formula content of the main glue is shown in Table 4.

[0085] Table 4

[0086]

[0087] The preparation method of the main glue includes: adding 30 parts of the first polyol with a number average molecular weight of 2500, 20 parts of the second polyol with a number average molecular weight of 2500, 10 parts of the third polyol with a number average molecular weight of 2000, 0.1 parts of antioxidant 1010, 0.1 parts of 1,4-butanediol, and 0.05 parts of glycerol to the reactor, starting stirring, cooling to 55°C, adding 15 parts of dimethyl carbonate and 3 parts of DMF, stirring for 30 minutes, ensuring that the raw materials in the reactor are completely stirred, keeping the temperature of the reactor at 55°C, adding 4 parts of TDI and 1 part of MDI. Heating to 75°C and stirring for 1 hour. Adding 0.002 parts of organic bismuth catalyst, heating to 80°C and continuing the reaction. When the viscosity reaches 250000 mPa.s at 80°C, turn off the heating, add 13 parts of dimethyl carbonate and 0.1 parts of 1,3-BG, stir for 1 hour, package and discharge the material to obtain the main glue, and seal and store;

[0088] Wherein, the first polyol, the second polyol and the third polyol are the same as those in Example 1.

[0089] The preparation method of the polyurethane adhesive comprises: preparing the main adhesive, the curing agent and the solvent (methyl ester) in proportion, and stirring them evenly to obtain the adhesive.

[0090] Comparative Example 1

[0091] This example provides a polyurethane adhesive and a preparation method thereof, which is basically the same as Example 1, except that the first polyol is not added and the second polyol is adjusted to 50 parts.

[0092] Comparative Example 2

[0093] This example provides a polyurethane adhesive and a preparation method thereof, which is basically the same as Example 1, except that the third polyol is not added and the first polyol is adjusted to 48 parts.

[0094] Comparative Example 3

[0095] This example provides a polyurethane adhesive and a preparation method thereof, which is basically the same as Example 1, with the only difference being that the amount of the third polyol is adjusted to 30 parts, the first polyol to 15 parts, and the second polyol to 15 parts.

[0096] Comparative Example 4

[0097] This example provides a polyurethane adhesive and a preparation method thereof, which is basically the same as Example 1, except that: a first polyol is prepared by reacting phthalic anhydride and diethylene glycol, and the specific preparation process is as follows: 20 parts of phthalic anhydride and 15 parts of diethylene glycol are added to a reaction kettle, the temperature is raised to 180°C, after the reaction produces water, the water produced by the reaction is gradually discharged, the temperature is raised by 5°C every 10 minutes, and the temperature is gradually raised to 225°C; when the acid value of the sample is 0.28 mgKOH / g and the hydroxyl value is 45.6 mgKOH / g, the temperature is lowered to obtain a first polyol with a number average molecular weight of about 2500;

[0098] The second polyol is prepared by the reaction of terephthalic acid, diethylene glycol and ethylene glycol. The specific preparation process is as follows: 24 parts of terephthalic acid, 8 parts of diethylene glycol and 5 parts of ethylene glycol are added into a reactor, the temperature is raised to 180°C, and after the water is produced by the reaction, the water produced by the reaction is gradually discharged, and the temperature is raised by 5°C every 10 minutes until it reaches 230°C. When the acid value of the sample is 0.34 mgKOH / g and the hydroxyl value is 45.8 mgKOH / g, the temperature is lowered to obtain a second polyol with a number average molecular weight of about 2500.

[0099] Performance Testing

[0100] The polyurethane adhesives prepared in Examples 1-4 and Comparative Examples 1-4 were used for carpet composite performance testing. The test results are shown in Table 5. The test method is: the main glue, curing agent, and solvent (methyl ester) are prepared in proportion, stirred evenly, and poured into a 25-mesh anilox roller glue tank for coating.

[0101] Specific operating parameters during the test: cutting width: 2.5cm; laminating pressure: 3kg; the test standards for initial adhesion and fastness are GB / T528-1998, and the test standard for peel strength is GB / T 7122.

[0102] Table 5

[0103]

[0104] Note: Hydrolysis resistance: Peel strength after being placed in high temperature (95°C) and high humidity (90%) environment for 7 days.

[0105] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

[0106] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

Claims

1. A polyurethane adhesive, comprising a primary adhesive and a curing agent, wherein the raw materials of the primary adhesive include polyols and polyisocyanates, and characterized in that: The polyol comprises a first polyol, a second polyol and a third polyol, the total addition amount of the first polyol and the second polyol and the feeding mass ratio of the third polyol are 1:0.10-0.35, and the feeding mass ratio of the first polyol to the second polyol is 1:0.3-0.75; The first polyol is prepared by reacting phthalic anhydride, trimellitic anhydride, diethylene glycol and methyl propylene glycol; The second polyol is prepared by reacting terephthalic acid, phthalic anhydride, diethylene glycol, neopentyl glycol and ethylene glycol; The third polyol is prepared by reacting modified vegetable oil and alkylene oxide, wherein the modified vegetable oil is prepared by reacting vegetable oil containing hydroxyl groups, propylene glycol and / or ethylene glycol.

2. The polyurethane adhesive according to claim 1, characterized in that The number average molecular weight of the first polyol is 2500-4500; the number average molecular weight of the second polyol is 2500-3000; and the number average molecular weight of the third polyol is 2000-3000.

3. The polyurethane adhesive according to claim 1, characterized in that In the first polyol, the molar ratio of the total amount of the phthalic anhydride and the trimellitic anhydride to the total amount of the diethylene glycol and the methyl propylene glycol is 1:1.02-1.15; In the first polyol, the molar ratio of the phthalic anhydride to the trimellitic anhydride is 1:0.1-0.25; and / or, In the first polyol, the molar ratio of the diethylene glycol to the methyl propylene glycol is 1:0.3-0.

6.

4. The polyurethane adhesive according to claim 1, characterized in that In the second polyol, the molar ratio between the total amount of the terephthalic acid and the phthalic anhydride added and the total amount of the diethylene glycol, the neopentyl glycol and the ethylene glycol added is 1:1.02-1.15; In the second polyol, the molar ratio of terephthalic acid to phthalic anhydride is 1:1.5-2.5; and / or, In the second polyol, the molar ratio of the diethylene glycol, the neopentyl glycol and the ethylene glycol is 1:0.35-0.55:0.8-1.

2.

5. The polyurethane adhesive according to claim 1, characterized in that The raw materials of the third polyol include hydroxyl-containing vegetable oil, propylene glycol and / or ethylene glycol, alkylene oxide, and alkali metal hydroxide; The vegetable oil containing hydroxyl groups includes castor oil, and the addition amount of the castor oil accounts for 25%-40% of the raw material of the third polyol in terms of mass percentage; The alkylene oxide is ethylene oxide and / or propylene oxide, and the amount of the alkylene oxide added accounts for 50%-65% of the raw material of the third polyol in terms of mass percentage; In terms of mass percentage, the added amount of propylene glycol and / or ethylene glycol accounts for 5%-15% of the raw material of the third polyol; In terms of mass percentage, the added amount of the alkali metal hydroxide accounts for 3%-5% of the raw material of the third polyol.

6. The polyurethane adhesive according to claim 1, characterized in that The preparation method of the third polyol comprises: mixing vegetable oil containing hydroxyl groups, propylene glycol and / or ethylene glycol, and alkali metal hydroxide, then adding alkylene oxide under a protective atmosphere at 100-130° C. and 0.1-0.4 MPa to react; adding phosphoric acid to neutralize the alkali metal hydroxide, filtering to remove impurities, and then performing reduced pressure distillation to obtain the third polyol.

7. The polyurethane adhesive according to claim 1, characterized in that The raw materials of the main rubber also include antioxidants, chain extenders, cross-linking agents, solvents, catalysts and terminators; Calculated by mass percentage, the raw materials of the main glue include: 40%-75% of polyol, 0.01%-0.5% of antioxidant, 0.05%-0.5% of chain extender, 0.01%-0.3% of cross-linking agent, 20%-50% of first solvent, 3%-10% of polyisocyanate, 0.001%-0.1% of catalyst and 0.01%-0.2% of terminator.

8. The polyurethane adhesive according to claim 7, characterized in that The polyisocyanate is toluene diisocyanate and / or diphenylmethane diisocyanate; and / or, the antioxidant is antioxidant 1010; and / or, the chain extender includes 1,4-butanediol; and / or, the cross-linking agent includes glycerol; and / or, the first solvent includes dimethyl carbonate and / or N,N-dimethylformamide; and / or, the catalyst includes an organic bismuth catalyst; and / or, the terminator includes 1,3-butanediol.

9. A method for preparing the polyurethane adhesive according to any one of claims 1 to 8, characterized in that: The preparation method comprises: The first polyol, the second polyol, the third polyol, the antioxidant, the chain extender, the crosslinking agent and a part of the solvent are stirred and mixed at 50-60° C., and then polyisocyanate is added, the temperature is raised to 70-80° C., the reaction is stirred, a catalyst is added, the temperature is raised to 80-85° C., the reaction is continued, and after the viscosity reaches the standard, the heating is stopped, the terminator and the remaining solvent are added, the mixture is stirred, and the material is discharged to obtain the polyurethane adhesive.

10. Use of the polyurethane adhesive according to any one of claims 1 to 8 as a binder in cloth-to-cloth lamination.

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