Hot melt adhesive composition and preparation method thereof

Abstract

The invention discloses a hot melt adhesive composition and a preparation method thereof, and belongs to the technical field of hot melt adhesives. The preparation method comprises the following steps: firstly, adding 80-90 parts of butyl rubber, 5-10 parts of styrene-isoprene-styrene block copolymer and 30-40 parts of tackifying resin into a reaction kettle, heating to 120-180 DEG C, stirring until complete melting, then adding 5-10 parts of maleic anhydride grafted polypropylene, 1-3 parts of auxiliaries and 0.01-0.1 part of initiator, stirring after vacuum degassing, and finally filtering and cooling to obtain the hot melt adhesive composition. The auxiliary agent has chemical action with the butyl rubber and the maleic anhydride grafted polypropylene, so that the auxiliary agent can stably exist in the hot melt adhesive composition and fully play a role, the hot melt adhesive composition is protected from being influenced by ultraviolet rays, oxidation reaction is effectively inhibited, the molecular structure of the hot melt adhesive composition is protected from being damaged, and the service life of the hot melt adhesive composition is prolonged. Therefore, the stability of the hot melt adhesive composition is improved, and the service life is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of hot melt adhesives, and specifically relates to a hot melt adhesive composition and a preparation method thereof. Background Art

[0002] A hot melt adhesive refers to an adhesive that is solid at room temperature, becomes liquid after heating and melting, and completes bonding within a few seconds after coating, wetting the adherend, and then pressing and cooling. It is made by melt-mixing a thermoplastic resin as the base material and containing a small amount of modifiers, viscosity regulators, fillers, antioxidants, etc., and has the advantage of rapid curing, which can solve the problem of difficult adhesion of some plastics. Currently, as a convenient-to-use and environmentally friendly adhesive, hot melt adhesives have been widely used in fields such as bookbinding, packaging, plywood, woodworking, and also in departments such as fibers, construction, civil engineering, automobiles, and electricity.

[0003] Among natural materials, asphalt, paraffin, rosin, etc. can be used as hot melt adhesives, but due to their disadvantages such as low strength, they have not been widely used. Subsequently, the emergence of polymer hot melt adhesives has promoted the development of hot melt adhesives in applications. The earliest polymer hot melt adhesives were thermoplastic polyethylene resins and butyl rubbers. Thereafter, people have also developed hot melt adhesives such as polyesters, polyamides, polyurethanes, and ethylene-vinyl acetate copolymers.

[0004] In the prior art, in order to prevent the hot melt adhesive from undergoing oxidation reactions under high-temperature environments and light conditions, protect the structure of the hot melt adhesive from being damaged, and improve the stability and service life of the hot melt adhesive, antioxidants and ultraviolet absorbers are usually added. However, in the prior art, antioxidants and ultraviolet absorbers are usually added in a simple physical mixing manner, without any interaction with the matrix resin or other raw materials, which results in the antioxidants being prone to gradually losing efficacy over time and thus gradually losing their protective effect. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a hot melt adhesive composition and a preparation method thereof.

[0006] The purpose of the present invention can be achieved by the following technical solutions: A preparation method of a hot melt adhesive composition includes the following steps: First, add butyl rubber, styrene-isoprene-styrene block copolymer, and tackifying resin into a reaction kettle, heat up to 120 - 180 °C and stir until completely melted, then add maleic anhydride grafted polypropylene, additives, and initiator, stir after vacuum degassing, and finally filter and cool to obtain the hot melt adhesive composition.

[0007] Further, the raw materials of the hot melt adhesive composition include, by weight: 80-90 parts of butyl rubber, 5-10 parts of styrene-isoprene-styrene block copolymer, 30-40 parts of tackifying resin, 5-10 parts of maleic anhydride grafted polypropylene, 1-3 parts of auxiliary agent, and 0.01-0.1 part of initiator.

[0008] Further, the tackifying resin is one or more of C5 petroleum resin, C9 petroleum resin, rosin ester, and terpene resin.

[0009] The styrene-isoprene-styrene block copolymer can improve the lightness and flexibility of the hot melt adhesive composition; maleic anhydride polypropylene can improve the bonding strength, water tightness, and gas barrier property of the hot melt adhesive composition, and improve the dispersion degree of each component.

[0010] Further, the auxiliary agent is prepared by the following steps: (1) Under nitrogen protection, 2,6-di-tert-butyl-4-bromomethylphenol, triethylamine, and chloroform are added to a fully dried three-necked flask, stirred evenly, and then 4-penten-1-amine is added. After the addition, the temperature is raised to 60°C and the reaction is carried out for 3 h. After the reaction is completed, it is first cooled to room temperature and then distilled under reduced pressure to obtain intermediate 1; the dosage ratio of 2,6-di-tert-butyl-4-bromomethylphenol, 4-penten-1-amine, triethylamine, and chloroform is 30 g:12 mL:16.7 mL:200 mL; Control the molar ratio of 2,6-di-tert-butyl-4-bromomethylphenol to 4-penten-1-amine to be 1:1.05-1.1. The -Br of 2,6-di-tert-butyl-4-bromomethylphenol and the -NH2 of 4-penten-1-amine undergo a nucleophilic substitution reaction. Triethylamine is an acid-binding agent, and the reaction process is as follows:

[0011] (2) Under nitrogen protection, intermediate 1, triethylamine, and dimethyl sulfoxide are added to a fully dried three-necked flask, stirred evenly, and then 1,7-dichloroheptane is added. After the addition, the temperature is raised to 70°C and the reaction is carried out for 3 h. After the reaction is completed, it is first cooled to room temperature and then distilled under reduced pressure to obtain intermediate 2; the dosage ratio of intermediate 1, 1,7-dichloroheptane, triethylamine, and dimethyl sulfoxide is 27 g:14 g:14 mL:240 mL; Control the molar ratio of intermediate 1 to 1,7-dichloroheptane to be 1.05-1.1:1. The -NH- of intermediate 1 and the -Cl of 1,7-dichloroheptane undergo a nucleophilic substitution reaction. Triethylamine is an acid-binding agent, and the reaction process is as follows:

[0012] (3) Under nitrogen protection, add intermediate 2, 2,4-dihydroxybenzophenone, and dimethyl sulfoxide into a dry four-necked flask, stir until completely dissolved, then slowly add 10% sodium hydroxide solution. After the addition is complete, heat up to 40 °C and keep the temperature for reaction for 8 h. After the reaction is completed, cool to room temperature, add deionized water, shake, and then let it stand for liquid separation. After measuring that the pH of the aqueous phase is neutral, dry the organic phase with anhydrous magnesium sulfate, filter, and distill the filtrate under reduced pressure to obtain the auxiliary agent; the dosage ratio of intermediate 2, 2,4-dihydroxybenzophenone, and dimethyl sulfoxide is 26 g: 14 g: 240 mL.

[0013] Under alkaline conditions, control the molar ratio of intermediate 2 and 2,4-dihydroxybenzophenone to be 1: 1.05 - 1.1. The -Cl of intermediate 2 and the -OH of 2,4-dihydroxybenzophenone undergo a nucleophilic substitution reaction, and the reaction process is as follows:

[0014] The auxiliary agent contains a benzophenone structure. The benzophenone structure has good thermal stability and chemical stability, and is mainly used to absorb the ultraviolet part in sunlight and fluorescent light sources, and can absorb ultraviolet light with a wavelength of 290 - 400 nm. Under sunlight and fluorescence, the hot melt adhesive composition will undergo an auto-oxidation reaction due to ultraviolet irradiation, and then will degrade and deteriorate in performance. After adding an auxiliary agent containing a benzophenone structure, it can selectively absorb high-energy ultraviolet light, convert it into harmless energy release or consumption, thereby protecting the hot melt adhesive composition from the influence of ultraviolet light.

[0015] The auxiliary agent contains a hindered phenol structure. The hindered phenol structure can capture free radicals in polymer materials, thereby interrupting the chain reaction of oxidation reactions and preventing the further oxidation of polymer materials; it can decompose hydroperoxides, reduce the oxidation rate, and prevent the further reaction and accumulation of oxidation products; it can also form a protective film on the surface of polymer materials to block oxygen from entering the interior of the material and reduce the chance of oxidation; in addition, it can enhance the thermal stability of the material, reduce the influence of thermal oxidation, and improve the resistance of the material to ultraviolet light. Therefore, adding an auxiliary agent containing a hindered phenol structure to the hot melt adhesive composition can effectively inhibit oxidation reactions, protect the molecular structure of the hot melt adhesive composition from being damaged, thereby improving the stability of the hot melt adhesive composition and extending its service life.

[0016] The benzophenone structure and the hindered phenol structure work together synergistically to effectively improve the antioxidant capacity and ultraviolet resistance of the hot melt adhesive composition, and extend the service life of the hot melt adhesive composition. At the same time, combining the benzophenone structure and the hindered phenol structure through a chemical reaction in one auxiliary agent molecule can also improve the atomic utilization rate, reduce the raw material consumption, and lower the cost.

[0017] In addition, the double bond of the auxiliary agent molecule can, under the action of high temperature and an initiator, form a chemical bond with the unreacted terminal double bonds in butyl rubber and maleic anhydride grafted polypropylene. As a result, the auxiliary agent can stably exist in the hot melt adhesive composition, fully play its role, effectively protect the hot melt adhesive composition, make it less susceptible to the influence of high temperature and ultraviolet irradiation, and greatly extend its service life.

[0018] Furthermore, the initiator is one or both of benzoyl peroxide and azobisisobutyronitrile.

[0019] The present invention also discloses a hot melt adhesive composition, which is prepared according to the preparation method of a hot melt adhesive composition as described above.

[0020] The beneficial effects of the present invention: There is a chemical interaction between the auxiliary agent and butyl rubber and maleic anhydride grafted polypropylene in the hot melt adhesive composition. Therefore, the auxiliary agent can stably exist in the hot melt adhesive composition, fully play its role, protect the hot melt adhesive composition from the influence of ultraviolet rays, effectively inhibit the oxidation reaction, protect the molecular structure of the hot melt adhesive composition from being damaged, thereby improving the stability of the hot melt adhesive composition and extending its service life. Detailed implementation manners

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0022] Example 1, preparation of the auxiliary agent, the specific steps are as follows: (1) Under nitrogen protection, 30 g of 2,6-di-tert-butyl-4-bromomethylphenol, 16.7 mL of triethylamine and 200 mL of chloroform are added to a 500 mL fully dried three-necked flask. After stirring evenly, 12 mL of 4-penten-1-amine is added. After the addition, the temperature is raised to 60 °C and the reaction is kept for 3 h. After the reaction is completed, it is first cooled to room temperature and then distilled under reduced pressure to obtain intermediate 1; (2) Under nitrogen protection, 27 g of intermediate 1, 14 mL of triethylamine and 240 mL of dimethyl sulfoxide are added to a 500 mL fully dried three-necked flask. After stirring evenly, 14 g of 1,7-dichloroheptane is added. After the addition, the temperature is raised to 70 °C and the reaction is kept for 3 h. After the reaction is completed, it is first cooled to room temperature and then distilled under reduced pressure to obtain intermediate 2; (3) Under nitrogen protection, 26 g of intermediate 2, 14 g of 2,4-dihydroxybenzophenone and 240 mL of dimethyl sulfoxide were added to a 500 mL dry four-necked flask, stirred until completely dissolved, and then 22 mL of 10% sodium hydroxide solution was slowly added. After the addition, the temperature was raised to 40 °C and the reaction was carried out for 8 h while maintaining the temperature. After the reaction, it was cooled to room temperature, deionized water was added, shaken, and then allowed to stand for liquid separation. After measuring that the pH of the aqueous phase was neutral, the organic phase was dried with anhydrous magnesium sulfate, filtered, and the filtrate was distilled under reduced pressure to obtain the auxiliary agent.

[0023] Example 2. Preparation of the hot melt adhesive composition, the specific steps are as follows: First, 80 parts by weight of butyl rubber, 5 parts by weight of styrene-isoprene-styrene block copolymer and 30 parts by weight of C5 petroleum resin were added to a reaction kettle, the temperature was raised to 120 °C and stirred until completely melted. Then, 5 parts by weight of maleic anhydride grafted polypropylene, 1 part by weight of the auxiliary agent prepared in Example 1 and 0.01 part by weight of benzoyl peroxide were added. After vacuum degassing, stirring was carried out, and finally filtration and cooling were carried out to obtain the hot melt adhesive composition.

[0024] Example 3. Preparation of the hot melt adhesive composition, the specific steps are as follows: First, 89 parts by weight of butyl rubber, 8 parts by weight of styrene-isoprene-styrene block copolymer, 20 parts by weight of C9 petroleum resin and 15 parts by weight of rosin ester were added to a reaction kettle, the temperature was raised to 180 °C and stirred until completely melted. Then, 7 parts by weight of maleic anhydride grafted polypropylene, 2 parts by weight of the auxiliary agent prepared in Example 1, 0.03 part by weight of benzoyl peroxide and 0.03 part by weight of azobisisobutyronitrile were added. After vacuum degassing, stirring was carried out, and finally filtration and cooling were carried out to obtain the hot melt adhesive composition.

[0025] Example 4. Preparation of the hot melt adhesive composition, the specific steps are as follows: First, 90 parts by weight of butyl rubber, 10 parts by weight of styrene-isoprene-styrene block copolymer and 40 parts by weight of terpene resin were added to a reaction kettle, the temperature was raised to 160 °C and stirred until completely melted. Then, 10 parts by weight of maleic anhydride grafted polypropylene, 3 parts by weight of the auxiliary agent prepared in Example 1 and 0.1 part by weight of benzoyl peroxide were added. After vacuum degassing, stirring was carried out, and finally filtration and cooling were carried out to obtain the hot melt adhesive composition.

[0026] Comparative Example 1. Preparation of the hot melt adhesive composition, the specific steps are as follows: The remaining steps remained unchanged, and only the auxiliary agent in Example 2 was removed to prepare the hot melt adhesive composition.

[0027] Comparative Example 2. Preparation of the hot melt adhesive composition, the specific steps are as follows: The remaining steps remained unchanged, and only the auxiliary agent in Example 2 was replaced with 1 part by weight of antioxidant 1010 to prepare the hot melt adhesive composition.

[0028] Comparative Example 3: Prepare a hot melt adhesive composition, and the specific steps are as follows: The remaining steps remain unchanged, and only the auxiliary agent in Example 2 is replaced with 1 part of ultraviolet absorber UV-531 to prepare a hot melt adhesive composition.

[0029] Comparative Example 4: Prepare a hot melt adhesive composition, and the specific steps are as follows: The remaining steps remain unchanged, and only the auxiliary agent in Example 2 is replaced with 0.5 part of antioxidant 1010 and 0.5 part of ultraviolet absorber UV-531 to prepare a hot melt adhesive composition.

[0030] Performance Test The hot melt adhesive compositions prepared in Examples 2-4 and Comparative Examples 1-4 are made into standard specimens according to GB / T 2790-1995, and the 180° peel strength is tested; after the hot melt adhesive compositions prepared in Examples 2-4 and Comparative Examples 1-4 are dry heat aged at 105 °C for 120 h, the 180° peel strength is tested according to GB / T 2790-1995; after the hot melt adhesive compositions prepared in Examples 2-4 and Comparative Examples 1-4 are ultraviolet aged under a 30 W ultraviolet lamp for 120 h at room temperature with a vertical irradiation distance of 20 cm, the 180° peel strength is tested according to GB / T 2790-1995. The test standards for all items are shown in the following table:

[0031] In the description of the specification, the description with reference to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0032] The above content is only an example and illustration of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the specific embodiments described or use similar methods for substitution, as long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a hot melt adhesive composition, characterized in that, It includes the following steps: First, add butyl rubber, styrene-isoprene-styrene block copolymer and tackifying resin into a reaction kettle, heat up to 120 - 180 °C and stir until completely melted. Subsequently, add maleic anhydride grafted polypropylene, auxiliary agent and initiator, stir after vacuum degassing, and finally filter and cool to obtain the hot melt adhesive composition; Among them, the auxiliary agent is prepared through the following steps: (1) Under nitrogen protection, add 2,6-di-tert-butyl-4-bromomethylphenol, triethylamine and chloroform into a flask, stir evenly, then add 4-penten-1-amine. After adding, heat up to 60 °C and react for 3 h. Cool to room temperature and distill under reduced pressure to obtain intermediate 1; (2) Under nitrogen protection, add intermediate 1, triethylamine and dimethyl sulfoxide into a flask, stir evenly, then add 1,7-dichloroheptane. After adding, heat up to 70 °C and react for 3 h. Cool to room temperature and distill under reduced pressure to obtain intermediate 2; (3) Under nitrogen protection, add intermediate 2, 2,4-dihydroxybenzophenone and dimethyl sulfoxide into a flask, stir until completely dissolved. Subsequently, add 10% sodium hydroxide solution. After adding, heat up to 40 °C and react for 8 h. Cool to room temperature, add deionized water, shake and then let it stand for layering. After measuring that the pH of the aqueous phase is neutral, dry the organic phase with anhydrous magnesium sulfate, filter, and distill the filtrate under reduced pressure to obtain the auxiliary agent.

2. The preparation method of a hot melt adhesive composition according to claim 1, characterized in that, The raw materials of the hot melt adhesive composition include, by weight: 80 - 90 parts of butyl rubber, 5 - 10 parts of styrene-isoprene-styrene block copolymer, 30 - 40 parts of tackifying resin, 5 - 10 parts of maleic anhydride grafted polypropylene, 1 - 3 parts of auxiliary agent, and 0.01 - 0.1 part of initiator.

3. The preparation method of a hot melt adhesive composition according to claim 1, characterized in that, The tackifying resin is one or more of C5 petroleum resin, C9 petroleum resin, rosin ester, and terpene resin.

4. The preparation method of a hot melt adhesive composition according to claim 1, characterized in that, The dosage ratio of 2,6-di-tert-butyl-4-bromomethylphenol, 4-penten-1-amine, triethylamine and chloroform in step (1) is 30 g:12 mL:16.7 mL:200 mL.

5. The preparation method of a hot melt adhesive composition according to claim 1, characterized in that, The dosage ratio of intermediate 1, 1,7-dichloroheptane, triethylamine and dimethyl sulfoxide in step (2) is 27 g:14 g:14 mL:240 mL.

6. The preparation method of a hot melt adhesive composition according to claim 1, characterized in that, The dosage ratio of intermediate 2, 2,4-dihydroxybenzophenone and dimethyl sulfoxide in step (3) is 26 g:14 g:240 mL.

7. The preparation method of a hot melt adhesive composition according to claim 1, characterized in that The initiator is one or two of benzoyl peroxide and azobisisobutyronitrile.

8. A hot melt adhesive composition, characterized in that, It is prepared by the preparation method of a hot melt adhesive composition according to any one of claims 1 - 7.

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