Preparation method of thermocuring reaction type EVA (Ethylene Vinyl Acetate) hot melt adhesive

Abstract

The invention discloses a preparation method of a thermocuring reaction type EVA (Ethylene Vinyl Acetate) hot melt adhesive, which comprises the following steps: S1, preparing raw materials: weighing vinyl acetate, a filler, a thermocuring agent, a plasticizer, a stabilizer and an anti-aging agent in proportion for later use; s2, mixing: adding the vinyl acetate and the thermal curing agent into dispersion equipment, mixing, heating in the mixing process, and sequentially adding the filler, the plasticizer, the stabilizer and the anti-aging agent in the heating process; the raw materials are filtered and treated, the purity of the raw materials is improved, the raw materials are fully dissolved in the adding process, in the thermocuring reaction, the thermocuring agent can fully react, cross-link and form a solid structure by precisely controlling the temperature, then the stabilizer and the anti-aging agent are adopted, and the curing effect is improved. The physical property of the EVA hot melt adhesive is improved.

Description

Technical Field

[0001] The invention relates to the technical field of hot melt adhesives, and in particular to a method for preparing a heat-curing reactive EVA hot melt adhesive. Background Art

[0002] Hot melt adhesive is a plastic adhesive. Its physical state changes with temperature within a certain temperature range, while its chemical properties remain unchanged. It is a non-toxic, odorless and environmentally friendly chemical product. Hot melt adhesive has the characteristics of fast bonding speed, does not contain any solvents, simple production process, low cost, low equipment investment, convenience and high efficiency when used by customers. Therefore, it is widely used in food packaging, fast assembly line packaging and sealing, home appliance sealing, book binding and other industries.

[0003] China Patent Network discloses "A modified EVA hot melt adhesive and its preparation method", with patent number: CN111647374A. This patent greatly improves the high and low temperature resistance and adhesion to cartons of existing EVA adhesives by introducing polyolefin plastomers POP and amorphous α-olefin copolymers APAO. The production and preparation process of the present invention is simple, does not use any solvents, has no chemical reactions, and has no harmful gas emissions. It is an environmentally friendly adhesive. Spraying points and spray strips under molten conditions can quickly solidify to achieve short-time bonding and breaking of materials, which is suitable for fast assembly line sealing operations. However, this patent is rough in the treatment of raw materials. The purity of raw materials is particularly important. When the raw materials are added, the raw materials cannot be properly dispersed and dissolved, which can easily lead to insufficient mixing of the raw materials. In the subsequent thermal curing reaction, the temperature cannot be accurately controlled, resulting in poor physical properties and stability of the finished product. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing a heat-curing reactive EVA hot melt adhesive, which has the advantages of being able to fully process and disperse the raw materials and fully undergo a heat-curing reaction.

[0005] To achieve the above object, the present invention provides the following technical solution: a heat-curing reactive EVA hot melt adhesive, comprising the following components:

[0006] Vinyl acetate 20-50%;

[0007] Filler 20-40%;

[0008] Thermal curing agent 1-10%;

[0009] Plasticizer 1-10%;

[0010] Stabilizer 1-5%;

[0011] Anti-aging agent 1-5%.

[0012] Preferably, the filler is silicon dioxide, the thermal curing agent is benzophenone peroxide, the plasticizer is an ester plasticizer, the stabilizer is a light stabilizer, and the anti-aging agent is an oxidant.

[0013] A method for preparing a heat-curing reactive EVA hot melt adhesive comprises the following steps:

[0014] S1 prepares raw materials: weighs vinyl acetate, filler, thermosetting agent, plasticizer, stabilizer and anti-aging agent according to proportion for standby use;

[0015] S2 mixing: putting vinyl acetate and a heat curing agent into a dispersing device, mixing them, and heating them during the mixing process, and adding fillers, plasticizers, stabilizers and anti-aging agents in sequence during the heating process;

[0016] S3 Melting: Put the mixed raw materials into the hot melt equipment and heat them to a suitable temperature to completely melt the vinyl acetate;

[0017] S4 Reaction curing: When the hot melt adhesive reaches the appropriate temperature, the thermal curing agent begins to initiate a reaction and causes the hot melt adhesive to cross-link when heated and form a solid structure;

[0018] S5 Cooling molding: After the heat curing reaction is completed, the hot melt adhesive is taken out of the heating equipment and properly cooled;

[0019] S6 packaging: packaging the cooled hot melt adhesive.

[0020] Preferably, in step S1, before weighing the raw material, it needs to be filtered and dried to remove impurities and improve the purity of the raw material.

[0021] Preferably, in step S2, the rotation speed of the dispersing device is 100-200 rpm, and the heating temperature is 80-150°C.

[0022] Preferably, in step S2, when adding fillers and other additives, the next raw material can be added only after the previous raw material is completely dispersed.

[0023] Preferably, in step S3, stirring or mixing is performed during the melting process to maintain uniformity, and the heating temperature is 100-200° C. and the stirring speed is 50-100 rpm.

[0024] Preferably, in step S4, the time of the thermal curing reaction is 1-3 hours, and the temperature during the thermal curing is 100-150°C.

[0025] Preferably, in step S5, the heat-cured EVA hot melt adhesive is molded by extrusion, injection or coating.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention improves the purity of the raw materials by filtering and processing the raw materials, and fully dissolves the raw materials during the addition process. In the thermal curing reaction, the temperature is precisely controlled so that the thermal curing agent can fully react, cross-link, and form a solid structure. Then, a stabilizer and an anti-aging agent are used to improve the physical properties of the EVA hot melt adhesive. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Embodiment 1

[0030] Vinyl acetate 40%;

[0031] Filler 30%;

[0032] Thermal curing agent 10%;

[0033] Plasticizer 10%;

[0034] Stabilizer 5%;

[0035] Anti-aging agent 5%.

[0036] A method for preparing a heat-curing reactive EVA hot melt adhesive comprises the following steps:

[0037] S1 prepares raw materials: weigh vinyl acetate, filler, thermosetting agent, plasticizer, stabilizer and anti-aging agent according to the proportion for use; before weighing the raw materials, they need to be filtered and dried to remove impurities and improve the purity of the raw materials.

[0038] S2 mixing: vinyl acetate and a thermosetting agent are put into a dispersing device, and mixed, and heated during the mixing process, and fillers, plasticizers, stabilizers and anti-aging agents are added in sequence during the heating process; the rotation speed of the dispersing device is 100 rpm, and the heating temperature is 120°C.

[0039] S3 Melting: Place the mixed raw materials into a hot melt device and heat to an appropriate temperature to completely melt the vinyl acetate. When adding fillers and other additives, the previous raw material must be completely dispersed before adding the next raw material. During the melting process, stir or mix to maintain uniformity. The heating temperature is 150°C and the stirring speed is 80 rpm.

[0040] S4 reaction curing: When the hot melt adhesive reaches the appropriate temperature, the thermal curing agent begins to initiate a reaction and causes the hot melt adhesive to cross-link when heated and form a solid structure; the thermal curing reaction time is 2 hours, and the thermal curing temperature is 120°C.

[0041] S5 Cooling molding: After the heat curing reaction is completed, the hot melt adhesive is removed from the heating device and properly cooled; the heat-cured EVA hot melt adhesive is molded by extrusion, injection or coating.

[0042] S6 packaging: packaging the cooled hot melt adhesive.

[0043] Embodiment 2

[0044] Vinyl acetate 50%;

[0045] Filler 30%;

[0046] Thermal curing agent 10%;

[0047] Plasticizer 5%;

[0048] Stabilizer 2%;

[0049] Anti-aging agent 3%.

[0050] A method for preparing a heat-curing reactive EVA hot melt adhesive comprises the following steps:

[0051] S1 prepares raw materials: weigh vinyl acetate, filler, thermosetting agent, plasticizer, stabilizer and anti-aging agent according to the proportion for use; before weighing the raw materials, they need to be filtered and dried to remove impurities and improve the purity of the raw materials.

[0052] S2 mixing: vinyl acetate and a thermosetting agent are put into a dispersing device, and mixed, and heated during the mixing process, and fillers, plasticizers, stabilizers and anti-aging agents are added in sequence during the heating process; the rotation speed of the dispersing device is 100 rpm, and the heating temperature is 120°C.

[0053] S3 Melting: Place the mixed raw materials into a hot melt device and heat to an appropriate temperature to completely melt the vinyl acetate. When adding fillers and other additives, the previous raw material must be completely dispersed before adding the next raw material. During the melting process, stir or mix to maintain uniformity. The heating temperature is 150°C and the stirring speed is 80 rpm.

[0054] S4 reaction curing: When the hot melt adhesive reaches the appropriate temperature, the thermal curing agent begins to initiate a reaction and causes the hot melt adhesive to cross-link when heated and form a solid structure; the thermal curing reaction time is 2 hours, and the thermal curing temperature is 120°C.

[0055] S5 Cooling molding: After the heat curing reaction is completed, the hot melt adhesive is removed from the heating device and properly cooled; the heat-cured EVA hot melt adhesive is molded by extrusion, injection or coating.

[0056] S6 packaging: packaging the cooled hot melt adhesive.

[0057] Embodiment 3

[0058] Vinyl acetate 50%;

[0059] Filler 35%;

[0060] Thermal curing agent 5%;

[0061] Plasticizer 5%;

[0062] Stabilizer 2%;

[0063] Anti-aging agent 3%.

[0064] A method for preparing a heat-curing reactive EVA hot melt adhesive comprises the following steps:

[0065] S1 prepares raw materials: weigh vinyl acetate, filler, thermosetting agent, plasticizer, stabilizer and anti-aging agent according to the proportion for use; before weighing the raw materials, they need to be filtered and dried to remove impurities and improve the purity of the raw materials.

[0066] S2 mixing: vinyl acetate and a thermosetting agent are put into a dispersing device, and mixed, and heated during the mixing process, and fillers, plasticizers, stabilizers and anti-aging agents are added in sequence during the heating process; the rotation speed of the dispersing device is 100 rpm, and the heating temperature is 120°C.

[0067] S3 Melting: Place the mixed raw materials into a hot melt device and heat to an appropriate temperature to completely melt the vinyl acetate. When adding fillers and other additives, the previous raw material must be completely dispersed before adding the next raw material. During the melting process, stir or mix to maintain uniformity. The heating temperature is 150°C and the stirring speed is 80 rpm.

[0068] S4 reaction curing: When the hot melt adhesive reaches the appropriate temperature, the thermal curing agent begins to initiate a reaction and causes the hot melt adhesive to cross-link when heated and form a solid structure; the thermal curing reaction time is 2 hours, and the thermal curing temperature is 120°C.

[0069] S5 Cooling molding: After the heat curing reaction is completed, the hot melt adhesive is removed from the heating device and properly cooled; the heat-cured EVA hot melt adhesive is molded by extrusion, injection or coating.

[0070] S6 packaging: packaging the cooled hot melt adhesive.

[0071] Embodiment 4

[0072] Vinyl acetate 45%;

[0073] Filler 40%;

[0074] Thermal curing agent 5%;

[0075] Plasticizer 5%;

[0076] Stabilizer 2%;

[0077] Anti-aging agent 3%.

[0078] A method for preparing a heat-curing reactive EVA hot melt adhesive comprises the following steps:

[0079] S1 prepares raw materials: weigh vinyl acetate, filler, thermosetting agent, plasticizer, stabilizer and anti-aging agent according to the proportion for use; before weighing the raw materials, they need to be filtered and dried to remove impurities and improve the purity of the raw materials.

[0080] S2 mixing: vinyl acetate and a thermosetting agent are put into a dispersing device, and mixed, and heated during the mixing process, and fillers, plasticizers, stabilizers and anti-aging agents are added in sequence during the heating process; the rotation speed of the dispersing device is 100 rpm, and the heating temperature is 120°C.

[0081] S3 Melting: Place the mixed raw materials into a hot melt device and heat to an appropriate temperature to completely melt the vinyl acetate. When adding fillers and other additives, the previous raw material must be completely dispersed before adding the next raw material. During the melting process, stir or mix to maintain uniformity. The heating temperature is 150°C and the stirring speed is 80 rpm.

[0082] S4 reaction curing: When the hot melt adhesive reaches the appropriate temperature, the thermal curing agent begins to initiate a reaction and causes the hot melt adhesive to cross-link when heated and form a solid structure; the thermal curing reaction time is 2 hours, and the thermal curing temperature is 120°C.

[0083] S5 Cooling molding: After the heat curing reaction is completed, the hot melt adhesive is removed from the heating device and properly cooled; the heat-cured EVA hot melt adhesive is molded by extrusion, injection or coating.

[0084] S6 packaging: packaging the cooled hot melt adhesive.

[0085] Embodiment 5

[0086] Vinyl acetate 40%;

[0087] Filler 40%;

[0088] Thermal curing agent 10%;

[0089] Plasticizer 5%;

[0090] Stabilizer 2%;

[0091] Anti-aging agent 3%.

[0092] A method for preparing a heat-curing reactive EVA hot melt adhesive comprises the following steps:

[0093] S1 prepares raw materials: weigh vinyl acetate, filler, thermosetting agent, plasticizer, stabilizer and anti-aging agent according to the proportion for use; before weighing the raw materials, they need to be filtered and dried to remove impurities and improve the purity of the raw materials.

[0094] S2 mixing: vinyl acetate and a thermosetting agent are put into a dispersing device, and mixed, and heated during the mixing process, and fillers, plasticizers, stabilizers and anti-aging agents are added in sequence during the heating process; the rotation speed of the dispersing device is 100 rpm, and the heating temperature is 120°C.

[0095] S3 Melting: Place the mixed raw materials into a hot melt device and heat to an appropriate temperature to completely melt the vinyl acetate. When adding fillers and other additives, the previous raw material must be completely dispersed before adding the next raw material. During the melting process, stir or mix to maintain uniformity. The heating temperature is 150°C and the stirring speed is 80 rpm.

[0096] S4 reaction curing: When the hot melt adhesive reaches the appropriate temperature, the thermal curing agent begins to initiate a reaction and causes the hot melt adhesive to cross-link when heated and form a solid structure; the thermal curing reaction time is 2 hours, and the thermal curing temperature is 120°C.

[0097] S5 Cooling molding: After the heat curing reaction is completed, the hot melt adhesive is removed from the heating device and properly cooled; the heat-cured EVA hot melt adhesive is molded by extrusion, injection or coating.

[0098] S6 packaging: packaging the cooled hot melt adhesive.

[0099] Comparative Examples 1-8 and Blank Experiment Group

[0100] In the EVA hot melt adhesives prepared in Comparative Examples 1-8 and the blank experimental group and Example 2, only the reaction temperature of thermal curing was adjusted.

[0101] Specific

[0102] In comparative example 1, the heat curing agent starts to initiate the reaction and causes the hot melt adhesive to crosslink when heated and form a solid structure; the heat curing reaction time is 2 hours, and the temperature during heat curing is 100°C.

[0103] In comparative example 2, the heat curing agent starts to initiate a reaction and causes the hot melt adhesive to crosslink when heated and form a solid structure; the heat curing reaction time is 2 hours, and the temperature during heat curing is 105°C.

[0104] In comparative example 3, the heat curing agent starts to initiate a reaction and causes the hot melt adhesive to crosslink when heated and form a solid structure; the heat curing reaction time is 2 hours, and the temperature during heat curing is 110°C.

[0105] In Comparative Example 4, the heat curing agent starts to initiate a reaction and causes the hot melt adhesive to crosslink when heated and form a solid structure; the heat curing reaction time is 2 hours, and the temperature during heat curing is 115°C.

[0106] In comparative example 5, the heat curing agent starts to initiate a reaction and causes the hot melt adhesive to crosslink when heated and form a solid structure; the heat curing reaction time is 2 hours, and the temperature during heat curing is 120°C.

[0107] In Comparative Example 6, the heat curing agent starts to initiate a reaction and causes the hot melt adhesive to crosslink when heated and form a solid structure; the heat curing reaction time is 2 hours, and the temperature during heat curing is 125°C.

[0108] In Comparative Example 7, the heat curing agent starts to initiate a reaction and causes the hot melt adhesive to crosslink when heated and form a solid structure; the heat curing reaction time is 2 hours, and the temperature during heat curing is 130°C.

[0109] In Comparative Example 8, the heat curing agent starts to initiate a reaction and causes the hot melt adhesive to crosslink when heated and form a solid structure; the heat curing reaction time is 2 hours, and the temperature during heat curing is 135°C.

[0110] In the blank experimental group, the thermal curing agent began to initiate a reaction and caused the hot melt adhesive to cross-link when heated and form a solid structure; the thermal curing reaction time was 2 hours, and the thermal curing temperature was 50°C.

[0111] Hardness test:

[0112] Operation steps: Use a hardness tester to test the hardness of the hot melt adhesives prepared in comparative examples 1-8, embodiment 2 and the blank experimental group after curing.

[0113] Place the hardness tester needle on the sample surface, apply a certain pressure, and record the measurement value.

[0114] Strength test:

[0115] Operation steps: The hot melt adhesives prepared in comparative examples 1-8, embodiment 2 and the blank experimental group were subjected to a tensile strength test.

[0116] Perform the test using a universal testing machine according to standard methods and record the test results.

[0117] Adhesion test:

[0118] Operation steps: The hot melt adhesives prepared in comparative examples 1-8, embodiment 2 and the blank experimental group were subjected to bonding experiments.

[0119] Bonding is performed according to the test methods and requirements, and the peel strength tester is used for testing, and relevant data such as bonding strength or peel strength are recorded.

[0120] The test results are shown in the following table

[0121]

[0122]

[0123] In summary, the EVA hot melt adhesive prepared by the present invention has good hardness and strength, and the adhesion test results are good. Among them, the EVA hot melt adhesive prepared under the conditions of Example 2 has the best performance.

[0124] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0125] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A heat-curing reactive EVA hot melt adhesive, characterized in that: The components include: Vinyl acetate 20-50%; Filler 20-40%; Thermal curing agent 1-10%; Plasticizer 1-10%; Stabilizer 1-5%; Anti-aging agent 1-5%.

2. A heat-curing reactive EVA hot melt adhesive according to claim 1, characterized in that: The filler is silicon dioxide, the heat curing agent is benzophenone peroxide, the plasticizer is an ester plasticizer, the stabilizer is a light stabilizer, and the anti-aging agent is an oxidant.

3. A method for preparing a heat-curing reactive EVA hot melt adhesive, characterized in that: The steps include: S1 prepares raw materials: weighs vinyl acetate, filler, thermosetting agent, plasticizer, stabilizer and anti-aging agent according to proportion for standby use; S2 mixing: putting vinyl acetate and a heat curing agent into a dispersing device, mixing them, and heating them during the mixing process, and adding fillers, plasticizers, stabilizers and anti-aging agents in sequence during the heating process; S3 Melting: Put the mixed raw materials into the hot melt equipment and heat them to a suitable temperature to completely melt the vinyl acetate; S4 Reaction curing: When the hot melt adhesive reaches the appropriate temperature, the thermal curing agent begins to initiate a reaction and causes the hot melt adhesive to cross-link when heated and form a solid structure; S5 Cooling molding: After the heat curing reaction is completed, the hot melt adhesive is taken out of the heating equipment and properly cooled; S6 packaging: packaging the cooled hot melt adhesive.

4. The method for preparing a heat-curing reactive EVA hot melt adhesive according to claim 3, characterized in that: In step S1, before weighing the raw material, it needs to be filtered and dried to remove impurities and improve the purity of the raw material.

5. The method for preparing a heat-curing reactive EVA hot melt adhesive according to claim 3, characterized in that: In the step S2, the rotation speed of the dispersing device is 100-200 rpm, and the heating temperature is 80-150°C.

6. The method for preparing a heat-curing reactive EVA hot melt adhesive according to claim 3, characterized in that: In step S2, when adding fillers and other additives, the previous raw material must be completely dispersed before adding the next raw material.

7. The method for preparing a heat-curing reactive EVA hot melt adhesive according to claim 3, characterized in that: In the step S3, stirring or mixing is performed during the melting process to maintain uniformity, and the heating temperature is 100-200° C. and the stirring speed is 50-100 rpm.

8. The method for preparing a heat-curing reactive EVA hot melt adhesive according to claim 3, characterized in that: In the step S4, the time of the thermal curing reaction is 1-3 hours, and the temperature during the thermal curing is 100-150°C.

9. The method for preparing a heat-curing reactive EVA hot melt adhesive according to claim 1, characterized in that: In step S5, the heat-cured EVA hot melt adhesive is molded by extrusion, injection or coating.

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