Hot melt adhesive and preparation process thereof

Abstract

The invention relates to the technical field of hot melt adhesives, and discloses a hot melt adhesive and a preparation process thereof.The hot melt adhesive is obtained after EVA, polyurethane, a modified POE elastomer, an antioxidant, an auxiliary and tackifying resin are heated, stirred and mixed to be uniform. Amido bonds and a large number of hydroxyl groups are introduced into side chains of the POE elastomer, the amido bonds and carbamate groups of polyurethane form hydrogen-bond interaction, and meanwhile, the hydroxyl groups and vinyl acetate in EVA form hydrogen-bond interaction, so that the POE elastomer, the EVA and the polyurethane have higher interface bonding performance and compatibility, and the POE elastomer, the EVA and the polyurethane form stable interface acting force; and the modified POE elastomer can play a role in compatibilizing EVA and polyurethane, and under the synergistic effect, the adhesive property and mechanical property of EVA are improved, so that the hot melt adhesive has higher peel strength, tensile strength and elongation at break.

Description

Technical Field

[0001] The present invention relates to the technical field of hot melt adhesives, in particular to a hot melt adhesive and a preparation process thereof. Background Art

[0002] Hot melt adhesives, such as EVA and polyurethane, are widely used in packaging, textiles, printing, sporting goods, and the automotive industry. However, conventional EVA and polyurethane hot melt adhesives suffer from poor adhesion and mechanical properties. Chemical modification of hot melt adhesives is a hot topic. Adding elastomers to hot melt adhesives can improve their mechanical properties.

[0003] POE elastomers have excellent toughness, elasticity, impact resistance, and aging resistance, and are widely used in adhesives, plastics, and rubber. Chinese patent application CN119320608A discloses a waterproof and sealing flexible hot-melt adhesive and its preparation process. Using EVA resin, POE polyolefin elastomer, maleic anhydride-grafted POE polyolefin elastomer, and SIS block copolymer as raw materials, the resulting hot-melt adhesive exhibits excellent low-temperature resistance. However, the patent fails to improve the EVA hot-melt adhesive's peel strength, tensile strength, and other properties. Summary of the Invention

[0004] The invention solves the problem of low bonding performance and mechanical properties of EVA.

[0005] The technical solution of the present invention is as follows: A preparation process of a hot melt adhesive: (1) adding POE elastomer, 2-(3,4-dihydroxyphenyl)acryloylethylamide and diisopropylbenzene peroxide into a torque rheometer for melt grafting, adding the product into xylene, heating and stirring, pouring the solution into acetone, filtering and adding the precipitate into a Soxhlet extractor, extracting with acetone, and drying to obtain a modified POE elastomer.

[0006] (2) Add EVA, polyurethane, modified POE elastomer, antioxidant, and additives into a reactor, heat and stir, then add tackifying resin, stir and mix, cool, and discharge to obtain hot melt adhesive.

[0007] Preferably, during the melt grafting in (1), the temperature of the torque rheometer is 150-165° C., and the grafting time is 8-14 min.

[0008] Preferably, the mass ratio of POE elastomer, 2-(3,4-dihydroxyphenyl)acryloylethylamide, and dicumyl peroxide in (1) is 100:(5-12):(0.25-0.4).

[0009] Preferably, the preparation process of 2-(3,4-dihydroxyphenyl)acryloylethylamide is as follows: dopamine hydrochloride and triethylamine are added to methanol, stirred, and then a tetrahydrofuran solution containing acryloyl chloride is added dropwise at 0-5°C, followed by a methanol solution containing triethylamine, with the molar ratio of dopamine hydrochloride, triethylamine, and acryloyl chloride controlled to be 1:(22-25):(11-12); the reaction is stirred at 20-25°C for 2-3 hours, filtered, and the filtrate is distilled under reduced pressure. The product is recrystallized from ethanol to obtain 2-(3,4-dihydroxyphenyl)acryloylethylamide. The reaction formula is as follows: .

[0010] Preferably, the temperature during heating and stirring in (2) is 160-170°C, the stirring time is 7-12 minutes, and the stirring and mixing time is 3-5 minutes.

[0011] Preferably, the mass ratio of EVA, polyurethane, modified POE elastomer, antioxidant, additive and tackifying resin in (2) is 100:(25-60):(10-30):(0.6-1):(8-15):(30-38).

[0012] Preferably, the antioxidant is antioxidant 1010 or antioxidant 168.

[0013] Preferably, the auxiliary agent is paraffin.

[0014] Preferably, the tackifying resin is a terpene resin or a petroleum resin.

[0015] The beneficial technical effect of the present invention is as follows: POE elastomer is melt-grafted with 2-(3,4-dihydroxyphenyl)acryloylethylamine to obtain a modified POE elastomer, which is then blended with EVA, polyurethane, tackifying resin, etc. to obtain an EVA hot melt adhesive. Amide bonds and a large number of hydroxyl groups are introduced into the side chains of the POE elastomer. The amide bonds form hydrogen bonds with the carbamate groups of the polyurethane, and at the same time, the hydroxyl groups form hydrogen bonds with the vinyl acetate in the EVA, so that the POE elastomer has stronger interfacial bonding performance and compatibility with EVA and polyurethane. The three form a stable interfacial force, and the modified POE elastomer can play a role in compatibilizing EVA and polyurethane. Under the synergistic effect, the bonding performance and mechanical properties of EVA are improved, and the hot melt adhesive has higher peel strength, tensile strength and elongation at break. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. Unless otherwise defined, all professional terms used hereinafter have the same meaning as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0017] The following EVA is ethylene-vinyl acetate copolymer, model TV1160, sourced from Ningbo Shun'ou Plastics Co., Ltd. The polyurethane is model UE-85AEU10FR, sourced from Ningbo Shun'ou Plastics Co., Ltd. The POE elastomer is ethylene-octene copolymer, model POE8401, sourced from Dongguan Baojia Plastics Co., Ltd. The terpene resin is model T-DB100, sourced from Guangdong Dingxin Polymerization Technology Co., Ltd. The petroleum resin is hydrogenated C9 petroleum resin, sourced from Guangdong Dingxin Polymerization Technology Co., Ltd.

[0018] Example 1 (1) Add 10 mmol of dopamine hydrochloride and 10 mmol of triethylamine to 40 mL of methanol. After stirring, add dropwise 1 mL of a tetrahydrofuran solution containing 12 mmol of acryloyl chloride at 0°C, and then add dropwise 2 mL of a methanol solution containing 15 mmol of triethylamine. Stir and react at 25°C for 2 h. After filtering, distill the filtrate under reduced pressure. The product is recrystallized from ethanol to obtain 2-(3,4-dihydroxyphenyl)acryloylethylamide.

[0019] (2) 200 g of POE elastomer, 10 g of 2-(3,4-dihydroxyphenyl)acryloylethylamide, and 0.5 g of diisopropylbenzene peroxide were added to a torque rheometer and melt grafted at 155 °C for 10 min. The product was added to 10 L of xylene, heated to 130 °C, and stirred for 3 h. The solution was poured into acetone, filtered, and the precipitate was added to a Soxhlet extractor, extracted with acetone, and dried to obtain a modified POE elastomer.

[0020] (3) Add 1 kg EVA, 250 g polyurethane, 100 g modified POE elastomer, 8 g antioxidant 1010, and 150 g paraffin into a reactor, heat to 165 ° C, stir for 10 min, add 370 g terpene resin, stir and mix for 3 min, cool, and discharge to obtain hot melt adhesive.

[0021] Example 2 (1) Add 10 mmol of dopamine hydrochloride and 10 mmol of triethylamine to 50 mL of methanol. After stirring, add dropwise 1 mL of a tetrahydrofuran solution containing 11 mmol of acryloyl chloride at 5°C, and then add dropwise 2 mL of a methanol solution containing 12 mmol of triethylamine. Stir and react at 20°C for 3 h. After filtering, distill the filtrate under reduced pressure. The product is recrystallized from ethanol to obtain 2-(3,4-dihydroxyphenyl)acryloylethylamide.

[0022] (2) 200 g of POE elastomer, 20 g of 2-(3,4-dihydroxyphenyl)acryloylethylamide, and 0.7 g of diisopropylbenzene peroxide were added to a torque rheometer and melt grafted at 150 °C for 14 min. The product was added to 11 L of xylene, heated to 130 °C, and stirred for 3 h. The solution was poured into acetone, filtered, and the precipitate was added to a Soxhlet extractor, extracted with acetone, and dried to obtain a modified POE elastomer.

[0023] (3) Add 1 kg EVA, 350 g polyurethane, 170 g modified POE elastomer, 10 g antioxidant 168, and 110 g paraffin into a reactor, heat to 160 ° C, stir for 12 minutes, add 300 g petroleum resin, stir and mix for 5 minutes, cool, and discharge to obtain hot melt adhesive.

[0024] Example 3 (1) 200 g of POE elastomer, 24 g of 2-(3,4-dihydroxyphenyl)acryloylethylamide (prepared in Example 1), and 0.8 g of diisopropylbenzene peroxide were added to a torque rheometer and melt grafted at 165 °C for 12 min. The product was added to 12 L of xylene, heated to 140 °C, and stirred for 2 h. The solution was poured into acetone, filtered, and the precipitate was added to a Soxhlet extractor, extracted with acetone, and dried to obtain a modified POE elastomer.

[0025] (2) Add 1 kg EVA, 480 g polyurethane, 240 g modified POE elastomer, 6 g antioxidant 1010, and 80 g paraffin into a reactor, heat to 170 ° C, stir for 7 minutes, add 380 g petroleum resin, stir and mix for 5 minutes, cool, and discharge to obtain hot melt adhesive.

[0026] Example 4 (1) 200 g of POE elastomer, 15 g of 2-(3,4-dihydroxyphenyl)acryloylethylamide (prepared in Example 1), and 0.6 g of diisopropylbenzene peroxide were added to a torque rheometer and melt grafted at 150 °C for 14 min. The product was added to 11 L of xylene, heated to 130 °C, and stirred for 3 h. The solution was poured into acetone, filtered, and the precipitate was added to a Soxhlet extractor, extracted with acetone, and dried to obtain a modified POE elastomer.

[0027] (2) Add 1 kg EVA, 600 g polyurethane, 300 g modified POE elastomer, 10 g antioxidant 1010, and 130 g paraffin into a reactor, heat to 170 ° C, stir for 10 minutes, add 330 g terpene resin, stir and mix for 4 minutes, cool, and discharge to obtain hot melt adhesive.

[0028] Comparative Example 1 (1) Add 1 kg EVA, 250 g polyurethane, 8 g antioxidant 1010, and 150 g paraffin into a reactor, heat to 165 ° C, stir for 10 min, add 370 g terpene resin, stir and mix for 3 min, cool, and discharge to obtain hot melt adhesive.

[0029] Comparative Example 2 (1) Add 1 kg EVA, 250 g polyurethane, 100 g POE elastomer, 8 g antioxidant 1010, and 150 g paraffin into a reactor, heat to 165 ° C, stir for 10 min, add 370 g terpene resin, stir and mix for 3 min, cool, and discharge to obtain hot melt adhesive.

[0030] Comparative Example 3 (1) 200 g of POE elastomer, 10 g of hydroxyethyl methacrylate, and 0.5 g of diisopropylbenzene peroxide were added to a torque rheometer and melt grafted at 155 °C for 10 min. The product was added to 10 L of xylene, heated to 130 °C, and stirred for 3 h. The solution was poured into acetone, filtered, and the precipitate was added to a Soxhlet extractor, extracted with acetone, and dried to obtain a modified POE elastomer.

[0031] (2) Add 1 kg EVA, 250 g polyurethane, 100 g modified POE elastomer, 8 g antioxidant 1010, and 150 g paraffin into a reactor, heat to 165 ° C, stir for 10 minutes, add 370 g terpene resin, stir and mix for 3 minutes, cool, and discharge to obtain hot melt adhesive.

[0032] Comparative Example 4 (1) 200 g of POE elastomer, 10 g of N-hydroxyethyl acrylamide (CAS registration number 7646-67-5), and 0.5 g of diisopropylbenzene peroxide were added to a torque rheometer and melt grafted at 155 °C for 10 min. The product was added to 10 L of xylene, heated to 130 °C, and stirred for 3 h. The solution was poured into acetone, filtered, and the precipitate was added to a Soxhlet extractor, extracted with acetone, and dried to obtain a modified POE elastomer.

[0033] (2) Add 1 kg EVA, 250 g polyurethane, 100 g modified POE elastomer, 8 g antioxidant 1010, and 150 g paraffin into a reactor, heat to 165 ° C, stir for 10 minutes, add 370 g terpene resin, stir and mix for 3 minutes, cool, and discharge to obtain hot melt adhesive.

[0034] The 180° peel strength of the hot melt adhesive was tested according to the method specified in GB / T 2790-1995. The bonding substrates were steel sheet and PET polyester sheet.

[0035] The tensile properties of hot melt adhesive cured products were tested according to the method specified in GB / T 1040.1-2018.

[0036] Table 1 Properties of hot melt adhesive Compared with Comparative Example 1, POE elastomer was added to the EVA hot melt adhesive of Comparative Example 2, and the elongation at break of the material increased, but the tensile strength decreased. This is mainly because the compatibility of POE elastomer with polyurethane is low, which is not conducive to improving the mechanical strength of the hot melt adhesive cured product.

[0037] In Examples 1 to 4, modified POE elastomers melt-grafted with 2-(3,4-dihydroxyphenyl)acryloylethylamine were added, and amide bonds and a large number of hydroxyl groups were introduced into the side chains of the POE elastomers. The amide bonds formed hydrogen bonds with the carbamate groups of the polyurethane, and at the same time, the hydroxyl groups formed hydrogen bonds with the vinyl acetate in the EVA, thereby making the POE elastomer have stronger interface bonding properties and compatibility with EVA and polyurethane, and the three formed a stable interface force. The modified POE elastomer can play a role in compatibilizing EVA and polyurethane. Under the synergistic effect, the bonding properties and mechanical properties of EVA are improved, and the hot melt adhesive has higher peel strength, tensile strength and elongation at break.

[0038] Comparative Example 3 uses hydroxyethyl methacrylate to melt-graft POE elastomer, which does not contain amide bonds and has a low hydroxyl content. Its interface bonding performance and compatibility with EVA and polyurethane are lower than those in Example 1, resulting in lower peel strength, tensile strength and elongation at break than in Example 1.

[0039] Comparative Example 4 uses N-hydroxyethyl acrylamide to melt-graft POE elastomer, which has a lower hydroxyl content and has lower interface bonding performance and compatibility with EVA than Example 1, resulting in lower peel strength, tensile strength and elongation at break than Example 1.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A process for preparing a hot melt adhesive, characterized in that: The preparation process comprises: (1) POE elastomer, 2-(3,4-dihydroxyphenyl)acryloylethylamide, and diisopropylbenzene peroxide are added to a torque rheometer for melt grafting, the product is added to xylene, heated and stirred, and the solution is poured into acetone. After filtering, the precipitate is added to a Soxhlet extractor, extracted with acetone, and dried to obtain a modified POE elastomer; (2) Add EVA, polyurethane, modified POE elastomer, antioxidant, and additives into a reactor, heat and stir, then add tackifying resin, stir and mix, cool, and discharge to obtain hot melt adhesive.

2. The preparation process of hot melt adhesive according to claim 1, characterized in that: During the melt grafting in (1), the temperature of the torque rheometer is 150-165° C., and the grafting time is 8-14 minutes.

3. The preparation process of hot melt adhesive according to claim 1, characterized in that: The mass ratio of POE elastomer, 2-(3,4-dihydroxyphenyl)acryloylethylamide and dicumyl peroxide in (1) is 100:(5-12):(0.25-0.4).

4. The preparation process of hot melt adhesive according to claim 3, characterized in that: The preparation process of 2-(3,4-dihydroxyphenyl)acryloylethylamide comprises: adding dopamine hydrochloride and triethylamine to methanol, adding dropwise a tetrahydrofuran solution containing acryloyl chloride at 0-5° C. after stirring, adding dropwise a methanol solution containing triethylamine, stirring at 20-25° C. for 2-3 hours, filtering, distilling the filtrate under reduced pressure, and recrystallizing the product from ethanol to obtain 2-(3,4-dihydroxyphenyl)acryloylethylamide.

5. The preparation process of hot melt adhesive according to claim 4, characterized in that: The molar ratio of dopamine hydrochloride, triethylamine and acryloyl chloride is 1:(22-25):(11-12).

6. The preparation process of hot melt adhesive according to claim 1, characterized in that: The temperature during heating and stirring in (2) is 160-170°C, the stirring time is 7-12 minutes, and the stirring and mixing time is 3-5 minutes.

7. The process for preparing the hot melt adhesive according to claim 1, characterized in that: The mass ratio of EVA, polyurethane, modified POE elastomer, antioxidant, additive and tackifying resin in (2) is 100: (25-60): (10-30): (0.6-1): (8-15): (30-38).

8. The process for preparing the hot melt adhesive according to claim 5, characterized in that: The antioxidant includes antioxidant 1010 or antioxidant 168; the auxiliary agent includes paraffin.

9. The process for preparing the hot melt adhesive according to claim 5, characterized in that: The tackifying resin includes terpene resin or petroleum resin.

10. A hot melt adhesive obtained by the preparation process according to any one of claims 1 to 9.