Polyurethane adhesive for silicone rubber

Abstract

The application discloses a polyurethane adhesive for silicone rubber, characterized in that the adhesive comprises the following components in parts by weight: diisocyanate 20-60 parts, polyester polyol 30-40 parts, small-molecule dihydric alcohol 5-10 parts, and dimethyl carbonate 10-20 parts; the polyester polyol is polymerized from the following components in mole: ethoxylated pentaerythritol 5-10 parts, dihydric alcohol 110-160 parts, and diacid 100-200 parts. The application aims to provide an environment-friendly polyurethane adhesive which has a good effect on bonding silicone rubber.

Description

Technical Field

[0001] This invention relates to the field of polymers, and more specifically to a polyurethane adhesive for silicone rubber. Background Technology

[0002] Environmentally friendly polyurethane adhesives refer to adhesives in which polyurethane is dispersed in water. They do not contain toxic substances such as benzene and formaldehyde, have no adverse effects on the environment, and are harmless to the human body. Environmentally friendly polyurethane adhesives have excellent comprehensive performance, including high strength, high transparency, strong adhesion, high toughness, and outstanding water resistance, making them an ideal alternative to solvent-based polyurethane rubber for footwear.

[0003] Especially in footwear products, with the development of the times, silicone rubber soles are becoming more and more common. However, traditional environmentally friendly polyurethane adhesives are not very effective at bonding silicone rubber. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an environmentally friendly polyurethane adhesive that has a better bonding effect on silicone rubber.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] An environmentally friendly polyurethane adhesive,

[0007] It comprises the following parts by weight:

[0008] Diisocyanate: 20-60 parts

[0009] Polyester polyol: 30-40 parts

[0010] Small molecule diols: 5-10

[0011] Dimethyl carbonate: 10-20 parts;

[0012] The polyester polyol is polymerized from the following molar amounts:

[0013] Pentaerythritol ethoxylate: 5-10 parts

[0014] Diol: 110–160 parts

[0015] Dicarboxylic acid: 100-200 parts.

[0016] As a further improvement of the present invention

[0017] The diol is a mixture of 1,6-hexanediol, 2-(2-methoxyphenoxy)-1,3-propanediol, and diphenylsilanediol.

[0018] As a further improvement of the present invention

[0019] The diol is a mixture of 1,6-hexanediol, 2-(2-methoxyphenoxy)-1,3-propanediol, and diphenylsilanediol in a molar ratio of 20:2:1.

[0020] As a further improvement of the present invention

[0021] The dicarboxylic acid is glutaric acid.

[0022] As a further improvement of the present invention

[0023] The preparation method of the polyester polyol is as follows:

[0024] A mixture of pentaerythritol ethoxylate, diol, and diacid was prepared and esterified at 140–160 °C for 1–2 h. The temperature was then raised to 170–200 °C, a catalyst was added, and the mixture was evacuated. The reaction was carried out at 170–200 °C for 1–2 h, and then raised to 210–250 °C for 1–3 h to obtain polyester polyol.

[0025] As a further improvement of the present invention

[0026] The catalyst is used to make up 0.2% of the mass of the dicarboxylic acid, and the catalyst is dibutyltin dilaurate.

[0027] As a further improvement of the present invention

[0028] The diisocyanate is diphenylmethane diisocyanate.

[0029] As a further improvement of the present invention

[0030] The small molecule diol is 1,4-butanediol.

[0031] As a further improvement of the present invention

[0032] The preparation method is as follows:

[0033] Dimethyl carbonate, polyester polyol, and small molecule diol were added to a three-necked flask, heated to 50-60°C, and held for 5 minutes. Then, diisocyanate was added, and the mixture was heated to 70-80°C and reacted for 2-3 hours to obtain the adhesive.

[0034] In this invention, the adhesive is mainly composed of diisocyanate, polyester polyol, and dimethyl carbonate. The key to this invention is the addition of polyester polyol, which effectively improves the adhesion to silicone rubber. The polyester polyol is mainly composed of pentaerythritol ethoxylate, diacid, and diol. The choice of diol is particularly important. Through continuous experimentation and exploration, the applicant discovered that when a small amount of 2-(2-methoxyphenoxy)-1,3-propanediol and diphenylsilanediol are added to the adhesive, the resulting polyester polyol can improve the adhesion to silicone rubber materials. Detailed Implementation

[0035] Example 1: Preparation of Polyester Polyols

[0036] Take 5 parts of pentaerythritol ethoxylate, 110 parts of diol and 100 parts of diacid, mix them, and esterify them at 140℃ for 2 hours. Then, raise the temperature to 170℃, add a catalyst, and evacuate the vacuum. React at 170℃ for 2 hours and then raise the temperature to 230℃ for 3 hours to obtain polyester polyol.

[0037] The dicarboxylic acid is glutaric acid;

[0038] The diol is a mixture of 1,6-hexanediol, 2-(2-methoxyphenoxy)-1,3-propanediol, and diphenylsilanediol in a molar ratio of 20:2:1.

[0039] The catalyst used is 0.2% of the mass of the dicarboxylic acid, and the catalyst is dibutyltin dilaurate.

[0040] Example 2: Preparation of Adhesive

[0041] 20 parts by weight of dimethyl carbonate, 30 parts by weight of the polyester polyol prepared in Example 1, and 10 parts by weight of 1,4-butanediol were added to a three-necked flask, heated to 50°C and held for 5 minutes. Then, 60 parts by weight of diphenylmethane diisocyanate were added, and the mixture was heated to 80°C and reacted for 3 hours to obtain the adhesive.

[0042] Comparative Example 1: Preparation of Polyester Polyols

[0043] Mix 100 parts of glutaric acid and 130 parts of 1,6-hexanediol, esterify at 140°C for 2 hours, then raise the temperature to 170°C, add a catalyst, apply vacuum, react at 170°C for 2 hours, and then raise the temperature to 230°C for 3 hours to obtain polyester polyol.

[0044] The catalyst used is 0.2% of the mass of the dicarboxylic acid, and the catalyst is dibutyltin dilaurate.

[0045] Comparative Example 2: Preparation of Adhesive

[0046] 20 parts by weight of dimethyl carbonate, 30 parts by weight of the polyester polyol prepared in Comparative Example 1, and 10 parts by weight of 1,4-butanediol were added to a three-necked flask, heated to 50°C and held for 5 min, and then 60 parts by weight of diphenylmethane diisocyanate were added. The mixture was then heated to 80°C and reacted for 3 h to obtain the adhesive.

[0047] Raw material list:

[0048] raw material factory Pentaerythritol ethoxylate Jinjinle (Hunan) Chemical Co., Ltd. glutaric acid Shanghai Yuanye Biotechnology Co., Ltd. 1,6-hexanediol Shanghai Jinjinle Industrial Co., Ltd. 2-(2-Methoxyphenoxy)-1,3-propanediol Shanghai Youhe Biotechnology Co., Ltd. Diphenylsilanediol Hebei Guanlang Biotechnology Co., Ltd. Dibutyltin dilaurate Shanghai Jinjinle Industrial Co., Ltd. dimethyl carbonate Shanghai Jinjinle Industrial Co., Ltd. 1,4-Butanediol Shanghai Jinjinle Industrial Co., Ltd. Diphenylmethane diisocyanate Shanghai Lianjing Polyurethane Industry Co., Ltd.

[0049] The adhesives obtained in Example 2 and Comparative Example 2 were subjected to peel strength tests:

[0050] Peel strength test: GB / T2790, test parameters are 30kg, 5cm, 120s, bonding material selection:

[0051] Group 1: Silicone rubber bonded to silicone rubber;

[0052] Group 2: Silicone rubber laminated with PU synthetic leather;

[0053] Group 3: Silicone rubber bonded to nylon fabric;

[0054] Group 4: Silicone rubber laminated with non-woven fabric.

[0055]

[0056]

[0057] The silicone rubber used is silicone rubber sheet produced by Hebei Hengming Rubber & Plastic Products Co., Ltd.

[0058] The polyurethane leather is made from PU synthetic leather material from Yiwu Burong Leather Co., Ltd.

[0059] The nylon fabric used is 30D nylon fabric from Guangzhou Shengji Xinghui Textile Co., Ltd.

[0060] The non-woven fabric used is unprinted non-woven fabric from Suzhou Dengyuan Textile Technology Co., Ltd.

[0061] The tests show that the adhesive prepared by this invention has good effects on bonding silicone rubber to silicone rubber, PU synthetic leather, nylon cloth, and non-woven fabric. This is mainly because 2-(2-methoxyphenoxy)-1,3-propanediol and diphenylsilanediol are added during the preparation of the polyester diol. In contrast, the polyester diol in Example 2 did not contain 2-(2-methoxyphenoxy)-1,3-propanediol and diphenylsilanediol, and its peel strength was significantly lower than that in Example 2.

[0062] In this invention, the adhesive is mainly composed of diisocyanate, polyester polyol, and dimethyl carbonate. The key to this invention is the addition of polyester polyol, which effectively improves the adhesion to silicone rubber. The polyester polyol is mainly composed of pentaerythritol ethoxylate, diacid, and diol. The choice of diol is particularly important. Through continuous experimentation and exploration, the applicant discovered that when a small amount of 2-(2-methoxyphenoxy)-1,3-propanediol and diphenylsilanediol are added to the adhesive, the resulting polyester polyol can improve the adhesion to silicone rubber materials.

[0063] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A polyurethane adhesive for silicone rubber, characterized in that: It comprises the following parts by weight: Diisocyanate: 20-60 parts Polyester polyol: 30-40 parts Small molecule diols: 5-10 Dimethyl carbonate: 10-20 parts; The polyester polyol is polymerized from the following molar amounts: Pentaerythritol ethoxylate: 5-10 parts Diol: 110–160 parts Dicarboxylic acid: 100-200 parts; The diol is a mixture of 1,6-hexanediol, 2-(2-methoxyphenoxy)-1,3-propanediol, and diphenylsilanediol.

2. The polyurethane adhesive for silicone rubber according to claim 1, characterized in that: The diol is a mixture of 1,6-hexanediol, 2-(2-methoxyphenoxy)-1,3-propanediol, and diphenylsilanediol in a molar ratio of 20:2:

1.

3. The polyurethane adhesive for silicone rubber according to claim 1, characterized in that: The dicarboxylic acid is glutaric acid.

4. The polyurethane adhesive for silicone rubber according to claim 1, characterized in that: The preparation method of the polyester polyol is as follows: A mixture of pentaerythritol ethoxylate, diol, and diacid was prepared and esterified at 140–160 °C for 1–2 h. The temperature was then raised to 170–200 °C, a catalyst was added, and the mixture was evacuated. The reaction was carried out at 170–200 °C for 1–2 h, and then raised to 210–250 °C for 1–3 h to obtain polyester polyol.

5. A polyurethane adhesive for silicone rubber according to claim 4, characterized in that: The amount of catalyst used is 0.2% of the mass of the dicarboxylic acid, and the catalyst is dibutyltin dilaurate.

6. The polyurethane adhesive for silicone rubber according to claim 1, characterized in that: The diisocyanate is diphenylmethane diisocyanate.

7. A polyurethane adhesive for silicone rubber according to claim 1, characterized in that: The small molecule diol is 1,4-butanediol.

8. A polyurethane adhesive for silicone rubber according to claim 1, characterized in that: The preparation method is as follows: Dimethyl carbonate, polyester polyol, and small molecule diol were added to a three-necked flask, heated to 50-60°C, and held for 5 minutes. Then, diisocyanate was added, and the mixture was heated to 70-80°C and reacted for 2-3 hours to obtain the adhesive.

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