Polyurethane adhesive and method for producing the same

Abstract

The application discloses a polyurethane adhesive and a preparation method thereof. The polyurethane adhesive comprises polyester polyol, chlorinated polyvinyl chloride, diisocyanate, a catalyst, diisocyanate trimer, a binary or multi-component chain extender and fumed silica. The polyurethane adhesive has superior weather resistance, strong flexibility and high-strength adhesive force, and has obvious progress compared with traditional polyurethane glue. The polyurethane adhesive has the advantages of safety, environmental protection and convenient construction, and is suitable for the adhesion of rubber, plastic, various leathers, EVA, PU and TPU and other materials.

Description

TECHNICAL FIELD

[0001] The present application relates to adhesive, in particular to a polyurethane adhesive and a preparation method thereof. BACKGROUND

[0002] Polyurethane adhesive refers to an adhesive containing urethane group (-NHCOO-) or isocyanate group (-NCO) in molecular chain, which has excellent performance and excellent chemical bonding force with various materials containing active hydrogen, such as rubber, foam, plastic, wood, leather, fabric, paper, ceramic, TPR, EVA, PU, TPU and the like. The polyurethane adhesive also has excellent shear strength and impact resistance, is suitable for various structural bonding fields, and has excellent flexibility. However, the polyurethane adhesive has poor weather resistance, and the bonding force is reduced or even lost in low or high temperature environment, which causes problems in use environment and service life of bonded products. The adhesive used in shoes, bags and the like is easily aged in long-term ultraviolet radiation, and therefore, the anti-aging and high temperature resistance of the adhesive are also very necessary. SUMMARY

[0003] Therefore, the technical problem to be solved by the present application is to provide a polyurethane adhesive with good weather resistance, which has excellent high temperature resistance and aging resistance after bonding products.

[0004] To solve the above technical problems, the present application adopts the following technical solutions:

[0005] A polyurethane adhesive with a molecular weight of 100-200 thousand, which comprises polyester polyol, chlorinated polyvinyl chloride, diisocyanate, catalyst (such as dibutyltin dilaurate and stannous octoate), diisocyanate trimer, dihydric or polyhydric chain extender (1,4-butanediol, glycerol, 1,6-hexanediol), and fumed silica.

[0006] In the present application, chlorinated polyvinyl chloride is added. The chlorinated polyvinyl chloride is a material obtained by further chlorination treatment based on polyvinyl chloride, and its molecular structure may contain multiple isomers. Its chemical formula is [C4H5Cl3] n , which represents one possible structure of chlorinated polyvinyl chloride. In fact, chlorinated polyvinyl chloride may contain multiple isomers. The inventors have tried different chlorinated polyvinyl chloride with different chlorine content and molecular weight for testing, and finally determined to select chlorinated polyvinyl chloride with chlorine content of 67±0.5% and lower molecular weight, and the average polymerization degree is 1000-3000.

[0007] Specifically, the polyurethane adhesive comprises the following components by weight:

[0008] Polyester polyol 13-18 parts by mass, chlorinated polyvinyl chloride 2-5 parts by mass, diisocyanate 6-9 parts by mass, diisocyanate trimer 1-3 parts by mass, dihydric or polyhydric chain extender 2-5 parts by mass; catalyst 0.05-0.1 parts by mass, fumed silica 0-2 parts by mass, ester or ketone solvent 50-70 parts by mass.

[0009] The molecular weight of the polyester polyol is 1000-5000. The polyester polyol is obtained by esterification of a polycarboxylic acid and a polyol, the polycarboxylic acid being at least one selected from terephthalic acid, isophthalic acid, 1,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decamethylene dicarboxylic acid, dodecamethylene dicarboxylic acid, and the polyol being at least one selected from ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, and cyclohexanediol.

[0010] The diisocyanate trimer comprises one or more of toluene diisocyanate trimer, diphenylmethane-4,4-diisocyanate trimer, hexamethylene diisocyanate trimer, and isophorone diisocyanate trimer.

[0011] The ester solvent comprises one or more of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl acetate, ethyl acetate, and butyl acetate in combination; and the ketone solvent comprises one or more of butanone, 3-methyl-2-butanone, cyclohexanone, acetone, and isophorone in combination.

[0012] The preparation method of the polyurethane adhesive comprises the following steps:

[0013] The polyester polyol and the chlorinated polyvinyl chloride are added into a reactor with a condensation reflux device, and stirred at 80-95°C until completely dissolved;

[0014] The diisocyanate, part of the solvent, and the catalyst are added subsequently, and the chain extender is added after the polymer molecular weight is greater than 30,000;

[0015] The solvent is added when the reaction reaches high viscosity, and stirred until completely dispersed and dissolved, to obtain a product with a viscosity of 800-5000 cPs;

[0016] The product is cooled, and the fumed silica is added to increase the viscosity, and then uniformly dispersed and stored in a tank.

[0017] Compared with the prior art, the polyurethane adhesive has the beneficial effects that:

[0018] The polyurethane adhesive has superior weather resistance, strong flexibility and high strength adhesion, has obvious progress compared with traditional polyurethane adhesive, has safety and environmental protection, construction convenience and other advantages, and is suitable for adhesion of rubber, plastic, various leathers, EVA, PU and TPU and other materials. DETAILED DESCRIPTION

[0019] In order to make the skilled in the art more clearly and intuitively understand the present application, the present application will be further described below.

[0020] The polyurethane adhesive of the present application has a molecular weight of 100-200 thousand, and comprises polyester polyol, chlorinated polyvinyl chloride, diisocyanate, diisocyanate trimer, binary or multi-component chain extender, catalyst, fumed silica, ester and / or ketone solvent.

[0021] Specifically, the polyurethane adhesive comprises:

[0022] The polyester polyol is 13-18 parts by mass, the chlorinated polyvinyl chloride is 2-5 parts by mass, the diisocyanate is 6-9 parts by mass, the diisocyanate trimer is 1-3 parts by mass, the binary or multi-component chain extender is 2-5 parts by mass, the catalyst is 0.05-0.1 parts by mass, the fumed silica is 0-2 parts by mass, and the ester and / or ketone solvent is 50-80 parts by mass.

[0023] The polyester polyol has a molecular weight of 3000. The polyester polyol is obtained by esterification reaction of terephthalic acid and ethylene glycol.

[0024] The chlorinated polyvinyl chloride has a chlorine content of 67±0.5%, and a lower molecular weight, and has an average polymerization degree of 1000-3000. In Examples 1-3 and Comparative Examples 1-3, the average polymerization degree is preferably 2000.

[0025] The diisocyanate comprises one or more of toluene diisocyanate, methylcyclohexyl diisocyanate, diphenylmethane-4,4-diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, naphthalene-1,5-diisocyanate, tetramethylxylylene diisocyanate.

[0026] The diisocyanate trimer comprises one or more of toluene diisocyanate trimer, diphenylmethane-4,4-diisocyanate trimer, hexamethylene diisocyanate trimer, isophorone diisocyanate trimer.

[0027] The ester solvent comprises one or more combinations of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl acetate, ethyl acetate, butyl acetate; the ketone solvent comprises one or more combinations of butanone, 3-methyl-2-butanone, cyclohexanone, acetone, isophorone.

[0028] The preparation method of the polyurethane adhesive of the present application comprises the following steps:

[0029] In a reactor with condensation reflux device, polyester polyol and chlorinated polyvinyl chloride are added, and stirred at 80-95℃ until completely dissolved;

[0030] Then, diisocyanate, part of the solvent and catalyst are added, and the polymer molecular weight is greater than 30,000, and then chain extender is added;

[0031] When the reaction reaches high viscosity, the remaining solvent is added, and stirred until completely dispersed and dissolved, to obtain a product with a viscosity of 800-5000 cPs;

[0032] After the product is cooled, fumed silica is added, and evenly dispersed, and then packed and stored.

[0033] The raw material composition of the examples and comparative examples is as follows:

[0034] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Polyester polyol (parts) 13 15 18 13 15 18 Chlorinated polyvinyl chloride (parts) 2 4 5 0 1.5 6 Toluene diisocyanate (parts) 6 0 4 6 0 4 Methylcyclohexyl diisocyanate (parts) 0 8 5 0 8 5 Chain extender 1,4-butanediol (parts) 2 3 5 2 3 5 Toluene diisocyanate trimer (parts) 1 2 3 1 2 3 Dimethyl carbonate (parts) 30 30 30 30 30 30 Butanone (parts) 46 37 28 48 39.5 27 Fumed silica (parts) 0 1 2 0 1 2 Total 100 100 100 100 100 100

[0035] Product testing: take a rubber sheet (containing butadiene-styrene, butadiene-acrylonitrile and various proportioned rubber sheets) with a width of 2.5 cm and a length of 8 cm, after surface treatment, apply the polyurethane adhesive prepared in examples 1-3 and the adhesive of comparative examples 1-3 to a thin state without missing glue, place in a 70℃ oven for 5 minutes until the adhesive is dry, bend and paste, press for 5 seconds under a pressure of 20 megapascals, and place in a 25℃ drying room for 30 minutes, then place in a 70℃, 90% humidity constant temperature and humidity box for more than 24 hours after the polyurethane glue is completely crystallized. The results are as follows:

[0036] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 stability No bounce No bounce No bounce Pop open immediately Pop open after 1 day Pop open after 2 days

[0037] The above test results show that the addition of chlorinated polyvinyl chloride improves the thermal stability of the adhesive, but the amount of addition is not the more the better, and too much addition reduces the proportion of other components, thereby reducing the thermal stability of the adhesive.

[0038] Test case:

[0039] A shoe factory in Jinjiang, Fujian, applies the polyurethane adhesive prepared in example 2 to the surface treatment of flyknit fabric and EVA bottom to bond them, and prepares 6 pairs of finished shoes, which are placed in a bending machine for bending test, and can all achieve a bending resistance data of 260-290 million times, creating a new high in the industry of polyurethane adhesive bending resistance.

[0040] In addition, in order to verify the effect of different chlorinated polyvinyl chloride, the comparative examples are set.

[0041] Comparative Example 4

[0042] The difference between this comparative example and Example 2 is that the chlorinated polyvinyl chloride has a chlorine content of 65% and an average polymerization degree of 2000.

[0043] Comparative Example 5

[0044] The difference between this comparative example and Example 2 is that the chlorinated polyvinyl chloride has a chlorine content of 70% and an average polymerization degree of 2000.

[0045] Comparative Example 6

[0046] The difference between this comparative example and Example 2 is that the chlorinated polyvinyl chloride has a chlorine content of 67% and an average polymerization degree of 800.

[0047] Comparative Example 7

[0048] The difference between this comparative example and Example 2 is that the chlorinated polyvinyl chloride has a chlorine content of 67% and an average polymerization degree of 1200.

[0049] Product test: take a rubber sheet (containing butadiene-styrene, butadiene-acrylonitrile and various proportioned rubber sheets) with a width of 2.5 cm and a length of 8 cm, after surface treatment, brush the adhesive of Comparative Examples 4-8 to a thin state without lack of glue, place in a 70°C oven for 5 minutes until the adhesive is dry, bend and paste, press for 5 seconds under a pressure of 20 megapascals, place in a 25°C drying room for 30 minutes, after the polyurethane glue is completely crystallized, place in a 70°C, 90% humidity constant temperature and humidity box, and bake for more than 24 hours. The results are as follows:

[0050] Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 stability Pop open after 3 days Pops open after 2.5 days Pops open after 3.5 days Pop open after 4 days

[0051] As can be seen from the table, even if chlorinated polyvinyl chloride is added, the chlorine content and average polymerization degree of this component have an effect on the product performance.

[0052] The above description of the embodiments is for the purpose of enabling a person of ordinary skill in the art to understand and apply the present application. Those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described herein to other embodiments without having to go through creative labor. Therefore, the present application is not limited to the embodiments herein, and any improvements and modifications made to the present application by those skilled in the art based on the disclosure of the present application should be within the scope of protection of the present application.

Claims

1. A polyurethane adhesive, characterized in that: The molecular weight is 100,000-200,000, and includes the following components in parts by weight: 13-18 parts by mass of polyester polyol, 2-5 parts by mass of chlorinated polyvinyl chloride, 6-9 parts by mass of diisocyanate, 1-3 parts by mass of diisocyanate trimer, 2-5 parts by mass of binary or multinary chain extender, 0.05-0.1 parts by mass of catalyst, 0-2 parts by mass of fumed silica, and 50-80 parts by mass of ester or ketone solvent; The chlorine content of the chlorinated polyvinyl chloride is 67±0.5%, and the average degree of polymerization is 2000-3000.

2. A polyurethane adhesive according to claim 1, characterized in that: The molecular weight of the polyester polyol is 1000-5000, and the polyester polyol is a polyester polyol obtained by esterification of a polycarboxylic acid and a polyol, wherein the polycarboxylic acid is selected from at least one of terephthalic acid, isophthalic acid, 1,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decamethylene dicarboxylic acid, and dodecamethylene dicarboxylic acid; and the polyol is selected from at least one of ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, and cyclohexanediol.

3. The polyurethane adhesive according to claim 1, characterized in that: The diisocyanate comprises one or more of toluene diisocyanate, methylcyclohexyl diisocyanate, diphenylmethane-4,4-diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, naphthalene-1,5-diisocyanate, and tetramethylxylylene diisocyanate.

4. The polyurethane adhesive according to claim 1, wherein The diisocyanate trimer includes one or more of toluene diisocyanate trimer, diphenylmethane-4,4-diisocyanate trimer, hexamethylene diisocyanate trimer, and isophorone diisocyanate trimer.

5. The polyurethane adhesive according to claim 1, characterized in that: The ester solvent includes one or more combinations of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl acetate, ethyl acetate, and butyl acetate.

6. The polyurethane adhesive according to claim 1, characterized in that: The ketone solvent includes one or more combinations of butanone, 3-methyl-2-butanone, cyclohexanone, acetone, and isophorone.

7. The polyurethane adhesive according to claim 1, characterized in that: The catalyst is selected from at least one of dibutyltin dilaurate and stannous octoate.

8. The polyurethane adhesive according to claim 1, wherein: The binary or multivalent chain extender is selected from one or more of 1,4-butanediol, glycerol, and 1,6-hexanediol.

9. The method for preparing a polyurethane adhesive according to any one of claims 1 to 8, wherein: The steps include: Add polyester polyol and chlorinated polyvinyl chloride into a reactor equipped with a condensation reflux device, stir at 80-95°C until they are completely dissolved; Then add diisocyanate, solvent and catalyst, and when the molecular weight of the polymer is greater than 30,000, add chain extender; When the reaction reaches high viscosity, add solvent and stir until it is completely dispersed and dissolved to obtain a product with a viscosity between 800 cPs and 5000 cPs. After the product is cooled, add fumed silica, disperse it evenly, and then store it in a can.