Ethylene-vinyl acetate copolymer hot melt adhesive composition, hot melt adhesive, and preparation method and application thereof

Abstract

The invention provides an ethylene-vinyl acetate copolymer hot melt adhesive composition, a hot melt adhesive, and a preparation method and application thereof. The ethylene-vinyl acetate copolymer hot melt adhesive composition comprises ethylene-vinyl acetate copolymer resin, a tackifier, wax, an antioxidant and a filler, wherein the content of a vinyl acetate structural unit in the ethylene-vinyl acetate copolymer resin is 25%-30%, and the melt index measured under the conditions of 190 DEG C and 2.15 kg is 350-450 g / 10 min. In the application, the following ethylene-vinyl acetate copolymer resin is selected: the content of a vinyl acetate structural unit is 26-30%, and the melt index measured under the conditions of 190 DEG C and 2.15 kg is 360-430 g / 10 min, so that the prepared ethylene-vinyl acetate copolymer hot melt adhesive has the characteristics of low viscosity and high peel strength, and further meets the use requirements in the packaging field.

Description

Technical Field

[0001] This application relates to the field of materials technology, and in particular to an ethylene-vinyl acetate copolymer hot melt adhesive composition, hot melt adhesive, its preparation method and application. Background Technology

[0002] Hot melt adhesive is a type of plastic adhesive that is solid at room temperature but melts into a liquid when heated to a certain temperature. When melted, the hot melt adhesive is applied to the surfaces of the materials to be bonded, stacked, and cooled to room temperature to join the materials together, giving them a certain bond strength. Hot melt adhesives offer advantages such as no solvent evaporation during use, no environmental pollution, availability in various shapes including blocks, films, strips, and granules, convenient packaging and storage, ease of use, and fast bonding speed. They are widely used in packaging, electronics, machinery, textiles, and other fields.

[0003] Hot melt adhesives are mainly composed of a polymer matrix, tackifiers, waxes, antioxidants, and fillers. Based on the polymer matrix, hot melt adhesives can be classified into: ethylene-vinyl acetate copolymer hot melt adhesives (EVA hot melt adhesives), polyethylene hot melt adhesives, atactic polypropylene hot melt adhesives, ethylene-ethyl acrylate copolymer hot melt adhesives, polyamide hot melt adhesives, polyester hot melt adhesives, ethylene-acrylic acid copolymer hot melt adhesives, and polyvinyl butyral hot melt adhesives, etc. Among these, ethylene-vinyl acetate copolymer hot melt adhesives are the most widely used type, possessing excellent bonding properties, hot-bonding ability on most materials, low melt viscosity, ease of use, excellent electrical properties, and good compatibility with other raw materials. They are widely used in electronic component encapsulation, photovoltaic module encapsulation, and automotive interior fixing, among other fields.

[0004] However, existing ethylene-vinyl acetate copolymer hot melt adhesives cannot simultaneously achieve both low viscosity and high peel strength, thus failing to meet the needs of the packaging industry. Summary of the Invention

[0005] This application provides an ethylene-vinyl acetate copolymer hot melt adhesive composition, a hot melt adhesive, a preparation method thereof, and its application to solve the above-mentioned technical problems.

[0006] To achieve the above objectives, the technical solution of this application is as follows: This application provides an ethylene-vinyl acetate copolymer hot melt adhesive composition, comprising ethylene-vinyl acetate copolymer resin (i.e., EVA resin), tackifier, wax, antioxidant, and filler. The ethylene-vinyl acetate copolymer resin contains 25%-30% vinyl acetate structural units (i.e., VA structural units) and has a melt index of 350-450 g / 10 min measured at 190°C and 2.15 kg. Preferably, the ethylene-vinyl acetate copolymer resin contains 26%-30% vinyl acetate structural units and has a melt index of 360-430 g / 10 min measured at 190°C and 2.15 kg. More preferably, the ethylene-vinyl acetate copolymer resin contains 27%-29% vinyl acetate structural units and has a melt index of 370-420 g / 10 min measured at 190°C and 2.15 kg.

[0007] In one embodiment of this application, the mass ratio of the ethylene-vinyl acetate copolymer resin, the tackifier, the wax, the antioxidant, and the filler is 50-60:30-40:1-5:0.3-0.4:1-5, preferably 52-60:32-40:2-5:0.35-0.4:2-5.

[0008] In one embodiment of this application, the tackifier is selected from at least one of petroleum resin, terpene resin, hydrogenated terpene resin, rosin, polymerized rosin, hydrogenated rosin, polystyrene resin, phenolic resin, and xylene resin.

[0009] In one embodiment of this application, the wax is selected from at least one of beeswax, shellac wax, palm wax, lignite wax, polyethylene wax, Fischer-Tropsch wax, microcrystalline wax, and paraffin wax.

[0010] In one embodiment of this application, the antioxidant is selected from at least one of 2,6-di-tert-butyl-p-cresol, tert-butylperoxide-2-ethylhexyl carbonate, dioctadecyl thiodipropionate, triisodecyl phosphite, and pentaerythritol ester.

[0011] In one embodiment of this application, the filler is selected from at least one of calcium carbonate, silicon dioxide, titanium dioxide, montmorillonite, clay, glass microspheres, and talc.

[0012] This application also provides a method for preparing an ethylene-vinyl acetate copolymer hot melt adhesive, comprising the following steps: S1. Mix ethylene-vinyl acetate copolymer resin, tackifier, wax, antioxidant and filler to obtain a mixture, wherein the ethylene-vinyl acetate copolymer resin contains 25%-30% vinyl acetate structural units and has a melt index of 350-450 g / 10 min measured at 190℃ and 2.15 kg. S2. The mixture is melt-blended and cooled to obtain the ethylene-vinyl acetate copolymer hot melt adhesive.

[0013] In one embodiment of this application, in step S2, the temperature of the melt mixing is 130-180°C, preferably 135-180°C; and the duration of the melt mixing is 30-50 min, preferably 35-50 min.

[0014] This application also provides an ethylene-vinyl acetate copolymer hot melt adhesive prepared according to the method described above.

[0015] This application also provides the application of the ethylene-vinyl acetate copolymer hot melt adhesive as described above in the packaging field.

[0016] The beneficial effects of this application are: In this application, by selecting the following ethylene-vinyl acetate copolymer resin: the content of vinyl acetate structural units is 26%-30% and the melt index measured at 190℃ and 2.15kg is 360-430g / 10min, the ethylene-vinyl acetate copolymer hot melt adhesive can be made to have both low viscosity and high peel strength characteristics, thereby meeting the needs of the packaging field. Detailed Implementation

[0017] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0018] One embodiment of this application provides an ethylene-vinyl acetate copolymer hot melt adhesive composition, which includes ethylene-vinyl acetate copolymer resin (i.e., EVA resin), tackifier, wax, antioxidant, and filler. The ethylene-vinyl acetate copolymer resin contains 25%-30% vinyl acetate structural units (i.e., VA structural units) and has a melt index of 350-450 g / 10 min measured at 190°C and 2.15 kg. Preferably, the ethylene-vinyl acetate copolymer resin contains 26% vinyl acetate structural units. More preferably, the vinyl acetate content in the ethylene-vinyl acetate copolymer resin is 27%-29%, and the melt index measured at 190°C and 2.15kg is 360-430g / 10min. More preferably, the vinyl acetate content in the ethylene-vinyl acetate copolymer resin is 27%-28%, and the melt index measured at 190°C and 2.15kg is 390-410g / 10min.

[0019] In this application, by selecting the following ethylene-vinyl acetate copolymer resin: the content of vinyl acetate structural units is 26%-30% and the melt index measured at 190℃ and 2.15kg is 360-430g / 10min, the ethylene-vinyl acetate copolymer hot melt adhesive can be made to have both low viscosity and high peel strength characteristics, thereby meeting the needs of the packaging field.

[0020] In one embodiment of this application, the mass ratio of ethylene-vinyl acetate copolymer resin, tackifier, wax, antioxidant and filler is 50-60:30-40:1-5:0.3-0.4:1-5, preferably 52-60:32-40:2-5:0.35-0.4:2-5.

[0021] In one embodiment of this application, the tackifier is selected from at least one of petroleum resin, terpene resin, hydrogenated terpene resin, rosin, polymerized rosin, hydrogenated rosin, polystyrene resin, phenolic resin and xylene resin.

[0022] In one embodiment of this application, the wax is selected from at least one of beeswax, shellac wax, palm wax, lignite wax, polyethylene wax, Fischer-Tropsch wax, microcrystalline wax, and paraffin wax.

[0023] In one embodiment of this application, the antioxidant is selected from at least one of 2,6-di-tert-butyl-p-cresol, tert-butylperoxide-2-ethylhexyl carbonate, dioctadecyl thiodipropionate, triisodecyl phosphite, and pentaerythritol ester.

[0024] In one embodiment of this application, the filler is selected from at least one of calcium carbonate, silicon dioxide, titanium dioxide, montmorillonite, clay, glass microspheres, and talc.

[0025] Another embodiment of this application provides a method for preparing an ethylene-vinyl acetate copolymer hot melt adhesive, comprising the following steps: S1. Mix ethylene-vinyl acetate copolymer resin, tackifier, wax, antioxidant and filler to obtain a mixture. The content of vinyl acetate structural units in the ethylene-vinyl acetate copolymer resin is 25%-30% and the melt index measured at 190℃ and 2.15kg is 350-450g / 10min. S2. Melt and knead the mixture, then cool it to obtain ethylene-vinyl acetate copolymer hot melt adhesive.

[0026] In one embodiment of this application, in step S1, during the mixing process, the rotation speed is 40-50 rpm, preferably 45-50 rpm; the mixing time is 30-50 min, preferably 35-50 min.

[0027] In one embodiment of this application, in step S2, the melting and mixing temperature is 130-180℃, preferably 135-180℃; the melting and mixing time is 30-50 min, preferably 35-50 min. During the melting and mixing process, the rotation speed is 40-60 rpm, preferably 45-60 rpm.

[0028] Another embodiment of this application provides an ethylene-vinyl acetate copolymer hot melt adhesive prepared according to the method described above.

[0029] Another embodiment of this application also provides the application of the ethylene-vinyl acetate copolymer hot melt adhesive as described above in the packaging field.

[0030] The following specific examples illustrate the present invention in detail. It should also be understood that the following examples are only for specific illustrative purposes and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention fall within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable scope; that is, those skilled in the art can make appropriate selections within the appropriate scope based on the description herein, and are not intended to limit themselves to the examples below.

[0031] In this application, the viscosity (180℃) was tested according to the single-cylinder rotational viscometer method in GB / T 2794-2022 Determination of Viscosity of Adhesives; The softening point was tested according to GB / T 15332-94 Determination of softening point of hot melt adhesives by ring and ball method; The content of VA structural units in EVA resin was tested according to GB / T 30925-2014 Plastics - Ethylene-vinyl acetate copolymer (EVAC) - Determination of vinyl acetate content in thermoplastic plastics; The melt flow index was determined in accordance with GB / T 3682.2-2018 Plastics Thermoplastics Determination of Melt Mass Flow Rate (MFR) and Melt Volume Flow Rate (MVR) Part 2: Test Methods for Materials Sensitive to Time-Temperature History and / or Humidity. During the test, the temperature was 190℃ and the load was 2.15kg. The peel strength was tested according to GB / T 2790-1995 Adhesives 180° Peel Strength Test Method Flexible Materials vs. Rigid Materials. The test was conducted on a universal tensile testing machine, and the separation rate of the clamps during the test was 100 mm / min.

[0032] Example 1 A method for preparing EVA hot melt adhesive, the specific steps of which are as follows: S1. Add 50 parts of EVA resin (VA structural unit content is 25% and melt index is 450g / 10min measured at 190℃ and 2.15kg), 40 parts of petroleum resin, 5 parts of paraffin wax, 0.3 parts of antioxidant dioctadecyl thiodipropionate and 1 part of calcium carbonate into a mixer and premix at 50rpm for 30min to obtain a mixture; S2. Transfer the mixture to a double-star mixer and melt-mix it for 50 minutes at a temperature of 180℃ and a speed of 40rpm. Take out the obtained molten colloid and cool it by passing it through two cooling water tanks in sequence. Then cut it to obtain EVA hot melt adhesive.

[0033] Example 2 A method for preparing EVA hot melt adhesive, the specific steps of which are as follows: S1. Add 60 parts of EVA resin (VA structural unit content is 30% and melt index is 350g / 10min measured at 190℃ and 2.15kg), 30 parts of petroleum resin, 1 part of Fischer-Tropsch wax, 0.4 parts of antioxidant tert-butyl peroxide-2-ethylhexyl carbonate and 5 parts of calcium carbonate into a mixer and premix at 40rpm for 50min to obtain a mixture; S2. Transfer the mixture to a double-star mixer and melt-mix it for 30 minutes at a temperature of 130℃ and a speed of 60rpm. Take out the obtained molten colloid and cool it by passing it through two cooling water tanks in sequence. Then cut it to obtain EVA hot melt adhesive.

[0034] Example 3 A method for preparing EVA hot melt adhesive, the specific steps of which are as follows: S1. Add 55 parts of EVA resin (VA structural unit content of 28% and melt index of 400g / 10min measured at 190℃ and 2.15kg), 35 parts of petroleum resin, 3 parts of polyethylene wax, 0.35 parts of antioxidant 2,6-di-tert-butyl-p-cresol and 3 parts of calcium carbonate into a mixer and premix at 45rpm for 40min to obtain a mixture; S2. Transfer the mixture to a double-star mixer and melt-mix it for 40 minutes at a temperature of 160℃ and a speed of 50rpm. Take out the obtained molten colloid and cool it by passing it through two cooling water tanks in sequence. Then cut it to obtain EVA hot melt adhesive.

[0035] Comparative Example 1 The difference between this comparative example and Example 3 is that the content of VA structural units in the EVA resin is 18% and the melt index measured at 190°C and 2.15 kg is 6 g / 10 min.

[0036] Comparative Example 2 The difference between this comparative example and Example 3 is that the content of VA structural units in the EVA resin is 18% and the melt index measured at 190°C and 2.15 kg is 150 g / 10 min.

[0037] Comparative Example 3 The difference between this comparative example and Example 3 is that the content of VA structural units in the EVA resin is 18% and the melt index measured at 190°C and 2.15 kg is 400 g / 10 min.

[0038] Comparative Example 4 The difference between this comparative example and Example 3 is that the content of VA structural units in the EVA resin is 28% and the melt index measured at 190°C and 2.15 kg is 6 g / 10 min.

[0039] Comparative Example 5 The difference between this comparative example and Example 3 is that the content of VA structural units in the EVA resin is 28% and the melt index measured at 190°C and 2.15 kg is 150 g / 10 min.

[0040] Comparative Example 6 The difference between this comparative example and Example 3 is that the content of VA structural units in the EVA resin is 33% and the melt index measured at 190°C and 2.15 kg is 6 g / 10 min.

[0041] Comparative Example 7 The difference between this comparative example and Example 3 is that the content of VA structural units in the EVA resin is 33% and the melt index measured at 190°C and 2.15 kg is 150 g / 10 min.

[0042] Comparative Example 8 The difference between this comparative example and Example 3 is that the content of VA structural units in the EVA resin is 33% and the melt index measured at 190°C and 2.15 kg is 400 g / 10 min.

[0043] Performance testing The viscosity (180°C) of the EVA hot melt adhesives prepared in Examples 1-3 and Comparative Examples 1-8 was tested, and the results are shown in Table 1. Peel strength tests were performed on the EVA hot melt adhesives prepared in Examples 1-3 and Comparative Examples 1-8, and the results are shown in Table 1.

[0044] Table 1 Test Results

[0045] As shown in Table 1, the EVA hot melt adhesives prepared in Comparative Examples 1-8 could not simultaneously achieve both low viscosity and high peel strength, while the EVA hot melt adhesive prepared in Example 3 could achieve both. This result indicates that, in this application, by selecting the following ethylene-vinyl acetate copolymer resin: a vinyl acetate structural unit content of 26%-30% and a melt index of 360-430 g / 10 min measured at 190°C and 2.15 kg, the prepared ethylene-vinyl acetate copolymer hot melt adhesive can achieve both low viscosity and high peel strength, thereby meeting the application requirements in the packaging field.

[0046] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. An ethylene-vinyl acetate copolymer hot melt adhesive composition comprising an ethylene-vinyl acetate copolymer resin, a tackifier, a wax, an antioxidant, and a filler, characterized in that, The content of the vinyl acetate structural unit in the ethylene-vinyl acetate copolymer resin is 25%-30%, and the melt index measured at 190 ℃ under a load of 2.15 kg is 350-450 g / 10 min.

2. The ethylene-vinyl acetate copolymer hot melt adhesive composition according to claim 1, wherein, The mass ratio of the ethylene-vinyl acetate copolymer resin, the tackifier, the wax, the antioxidant, and the filler is 50-60:30-40:1-5:0.3-0.4:1-5.

3. The ethylene-vinyl acetate copolymer hot melt adhesive composition according to claim 1, wherein, The tackifier is at least one selected from the group consisting of petroleum resin, terpene resin, hydrogenated terpene resin, rosin, polymerized rosin, hydrogenated rosin, polystyrene-based resin, phenolic resin, and xylene resin.

4. The ethylene-vinyl acetate copolymer hot melt adhesive composition according to claim 1, wherein, The wax is at least one selected from the group consisting of beeswax, shellac wax, palm wax, montan wax, polyethylene wax, Fischer-Tropsch wax, microcrystalline wax, and paraffin wax.

5. The ethylene-vinyl acetate copolymer hot melt adhesive composition according to claim 1, wherein, The antioxidant is at least one selected from the group consisting of 2,6-di-tert-butyl-p-cresol, tert-butyl peroxy-2-ethylhexyl carbonate, distearyl thiodipropionate, triisodecyl phosphite, and pentaerythritol ester.

6. The ethylene-vinyl acetate copolymer hot melt adhesive composition according to claim 1, wherein, The filler is at least one selected from the group consisting of calcium carbonate, silicon dioxide, titanium dioxide, montmorillonite, kaolin, glass microbeads, and talc powder.

7. A process for preparing an ethylene-vinyl acetate copolymer hot melt adhesive, characterized by, The method comprises the following steps: S1. mixing an ethylene-vinyl acetate copolymer resin, a tackifier, a wax, an antioxidant, and a filler to obtain a mixture, the content of the vinyl acetate structural unit in the ethylene-vinyl acetate copolymer resin being 25%-30%, and the melt index measured at 190 ℃ under a load of 2.15 kg being 350-450 g / 10 min; S2. melt-kneading the mixture, cooling, and obtaining the ethylene-vinyl acetate copolymer hot melt adhesive.

8. The production method according to claim 7, wherein In step S2, the temperature of the melt-kneading is 130-180 ℃, and the time length of the melt-kneading is 30-50 min.

9. An ethylene-vinyl acetate copolymer hot melt adhesive prepared according to the method of claim 7 or 8.

10. Use of the ethylene-vinyl acetate copolymer hot melt adhesive of claim 9 in the packaging field.

Images