Preparation process of EVA (Ethylene Vinyl Acetate) hot melt adhesive with excellent conductivity

Abstract

The invention discloses a preparation process of an EVA hot melt adhesive with excellent conductivity, and belongs to the technical field of preparation processes of hot melt adhesives, the preparation process of the EVA hot melt adhesive with excellent conductivity specifically comprises the following steps: step 1, selecting raw materials; 2, melting and mixing the raw materials to form a mixture; 3, extruding the mixture, and filtering to remove impurities; 4, quantitatively taking the mixture, injecting the mixture into a mold, controlling the temperature, and waiting for cooling and molding to form a molded product; and 5, opening the mold, taking out a molded product, and then sequentially shaping, shearing, sub-packaging and storing to obtain a final molded product of the EVA hot melt adhesive. According to the invention, the viscosity value of the finally produced EVA hot melt adhesive can be effectively ensured, the service life of the finally produced EVA hot melt adhesive can be effectively prolonged, the conductivity of the finally produced EVA hot melt adhesive can be enhanced, the finally produced EVA hot melt adhesive can better meet the bonding requirements of electronic devices, and the application range of the EVA hot melt adhesive in production and life is widened.

Description

Technical Field

[0001] The invention relates to the technical field of hot melt adhesive preparation technology, and more specifically to a preparation technology of EVA hot melt adhesive with excellent conductive performance. Background Art

[0002] EVA hot melt adhesive is a solvent-free, water-free, 100% solid fusible polymer. It is solid at room temperature and becomes a liquid adhesive with a certain viscosity when heated and melted to a certain degree. It is light brown translucent or white after melting. The main component of hot melt adhesive, that is, the basic resin, is made by copolymerizing ethylene and vinyl acetate under high pressure, and then mixed with tackifiers, viscosity regulators, antioxidants, etc. to make hot melt adhesive.

[0003] At present, in the EVA hot melt adhesive production industry, the commonly used EVA hot melt adhesive is only used to ensure that it has a certain viscosity value. Then, the bonding of electronic devices requires a certain conductivity, and many common hot melt adhesives on the market do not have conductivity, or have poor conductivity, and therefore do not meet the bonding requirements of electronic devices.

[0004] Therefore, in view of this, the existing structure is studied and improved, and a preparation process of EVA hot melt adhesive with excellent conductive properties is provided, in order to achieve a more practical purpose. Summary of the invention

[0005] 1. Technical issues to be solved

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a process for preparing an EVA hot melt adhesive with excellent conductive properties, which can effectively ensure the viscosity value of the final produced EVA hot melt adhesive, effectively increase the service life of the final produced EVA hot melt adhesive, and enhance the conductive properties of the final produced EVA hot melt adhesive, so that the final produced EVA hot melt adhesive can better meet the bonding requirements of electronic devices, thereby improving the scope of application of the EVA hot melt adhesive in production and life.

[0007] 2. Technical solution

[0008] To solve the above problems, the present invention adopts the following technical solutions.

[0009] A preparation process of an EVA hot melt adhesive with excellent conductive properties, the specific implementation steps of the preparation process are as follows:

[0010] Step 1: Select the raw materials. The specific raw materials are proportioned by mass as follows:

[0011]

[0012] The auxiliary agent includes one or more of a plasticizer, a stabilizer and an antioxidant, and the filler includes one or more of silica fume, talcum powder, aluminum powder and copper powder;

[0013] The above raw materials are quantitatively weighed, dried and impurity-removed respectively to complete the configuration and pretreatment of the raw materials;

[0014] Step 2: Put all the raw materials into the melting machine in sequence, melt and mix them to form a mixture. At this time, the melting conditions are controlled;

[0015] Step 3: Extrude and filter the mixture to remove impurities, so that the mixture reaches a new storage container, and control the temperature of the storage container to ensure that the mixture is in a molten state;

[0016] Step 4: quantitatively take the mixed material, inject the taken mixed material into the mold, control the temperature and wait for cooling to form a molded product;

[0017] Step 5: Open the mold, take out the molded product, and then perform shaping, shearing, packaging and storage in sequence to obtain the final EVA hot melt adhesive molded product.

[0018] Furthermore, in the step one, the selected raw materials include 120 parts of ethylene-vinyl acetate copolymer, 25 parts of tackifying resin, 12 parts of plasticizer, 8 parts of stabilizer, 1 part of antioxidant, 6 parts of silica fume, 5 parts of talc, 8 parts of aluminum powder, and 16 parts of copper powder.

[0019] Furthermore, 16 parts of copper powder are replaced with a mixture of copper powder and silver powder, including 14 parts of copper powder and 2 parts of silver powder.

[0020] Furthermore, in the step 1, when the ethylene-vinyl acetate copolymer, the tackifying resin, the auxiliary agent and the filler are dried, a vacuum low-temperature drying method is adopted for drying.

[0021] Furthermore, in the step 1, during the impurity removal operation, the auxiliary agent and the filler are pulverized simultaneously, and at the same time, various components contained in the auxiliary agent are directly mixed evenly.

[0022] Furthermore, in the step 2, the temperature of the melter is first increased to 180°C, and then ethylene-vinyl acetate copolymer and tackifying resin are added and stirred until the two are evenly mixed, and then the mixture of additives and the mixture of fillers are added, and the temperature is increased again to 220-240°C, and stirring is continued for not less than 50 minutes until all substances are evenly mixed.

[0023] Furthermore, in the step three, temperature detection is performed during extrusion and filtration and impurity removal, wherein the temperature during extrusion is not lower than 160°C, and the temperature during filtration and impurity removal is not lower than 130°C.

[0024] Furthermore, in the step 4, when the mixture is injected into the mold, a funnel is used for injection, and at the same time, the mold is controlled to vibrate continuously at a low frequency.

[0025] Furthermore, in step 4, during the cooling and molding process, the temperature is controlled to drop to 60° C. within 10 minutes, and then allowed to stand until the temperature reaches room temperature, and then allowed to stand for another 20 minutes.

[0026] Furthermore, the viscosity value of EVA hot melt adhesive at 120°C is 13000cps;

[0027] The volume resistivity of EVA hot melt adhesive is 4.8Ω*cm.

[0028] 3. Beneficial effects

[0029] Compared with the prior art, the advantages of the present invention are:

[0030] In the present scheme, in the production and preparation of EVA, ethylene-vinyl acetate copolymer, tackifying resin, auxiliary agent and filler are used as raw materials, wherein ethylene-vinyl acetate copolymer and tackifying resin can effectively ensure the viscosity value of the final EVA hot melt adhesive produced, and the plasticizer, stabilizer and antioxidant in the auxiliary agent can effectively increase the service life of the final EVA hot melt adhesive produced, and the silica fume, talcum powder, aluminum powder and copper powder in the filler can enhance the conductive properties of the final EVA hot melt adhesive produced. In this way, the final EVA hot melt adhesive can effectively meet the bonding requirements of electronic devices better, thereby improving the application scope of the EVA hot melt adhesive in production and life. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the preparation process of the present invention. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0033] Embodiment 1:

[0034] See also Figure 1 , a preparation process of EVA hot melt adhesive with excellent conductive properties, the specific implementation steps of the preparation process are as follows:

[0035] Step 1: Select raw materials:

[0036] Specifically, the selected raw materials include 120 parts of ethylene-vinyl acetate copolymer, 25 parts of tackifying resin, 12 parts of plasticizer, 8 parts of stabilizer, 1 part of antioxidant, 6 parts of silica fume, 5 parts of talc, 8 parts of aluminum powder, and 16 parts of copper powder. Both aluminum powder and copper powder have certain electrical conductivity, among which copper powder has better electrical conductivity.

[0037] The above raw materials are quantitatively weighed, dried and impurity-removed respectively to complete the configuration and pretreatment of the raw materials;

[0038] Specifically, at this time, 16 parts of copper powder can be replaced by a mixture of copper powder and silver powder, including 14 parts of copper powder and 2 parts of silver powder. Compared with copper powder, silver powder has better conductivity, but considering the high price of silver powder, controlling the ratio of silver powder to copper powder can ensure that the cost is within a controllable range while improving conductivity.

[0039] Specifically, when drying ethylene-vinyl acetate copolymer, tackifying resin, auxiliary agent and filler, vacuum low-temperature drying is adopted. The vacuum low-temperature drying method can reduce the loss of substances caused by drying volatilization.

[0040] Specifically, during the impurity removal operation, the additive and filler are pulverized simultaneously, and at the same time, various components contained in the additive are directly mixed evenly. Through the pulverization operation, the uniformity of the final mixture can be effectively guaranteed.

[0041] Step 2: Put all the raw materials into the melting machine in sequence, melt and mix them to form a mixture. At this time, the melting conditions are controlled;

[0042] Specifically, first increase the temperature of the melter to 180°C, then add ethylene-vinyl acetate copolymer and tackifying resin, and stir until the two are evenly mixed, then add the mixture of additives and the mixture of fillers, increase the temperature again to 220-240°C, and continue stirring for not less than 50 minutes until all substances are evenly mixed. The state of ethylene-vinyl acetate copolymer and tackifying resin is similar, and mixing in advance helps to improve the subsequent mixing efficiency, and then controlling the temperature can ensure that the organic substances are evenly mixed and facilitate the uniform distribution of inorganic substances in the organic substances.

[0043] Step 3: Extrude and filter the mixture to remove impurities, so that the mixture reaches a new storage container, and control the temperature of the storage container to ensure that the mixture is in a molten state;

[0044] Specifically, temperature detection is performed during extrusion and filtration and impurity removal, wherein the temperature during extrusion is not less than 160° C., and the temperature during filtration and impurity removal is not less than 130° C. When the temperature is controlled, the mixture can be kept in a molten state at all times, avoiding premature solidification and uneven mixing of the final EVA hot melt adhesive.

[0045] Step 4: quantitatively take the mixed material, inject the taken mixed material into the mold, control the temperature and wait for cooling to form a molded product;

[0046] Specifically, when the mixture is injected into the mold, a funnel is used for injection, and at the same time, the mold is controlled to vibrate continuously at a low frequency. The funnel is used to inject the mixture, which can conveniently control the injection speed, and the low-frequency vibration can effectively remove the gas in the mixture.

[0047] Specifically, during the cooling and molding process, the temperature is controlled to drop to 60°C within 10 minutes, and then left to stand until the temperature reaches room temperature, and then left to stand for another 20 minutes. The step-by-step cooling method can avoid temperature differences within the mixture, thereby avoiding affecting the quality of the final product.

[0048] Step 5: Open the mold, take out the molded product, and then perform shaping, shearing, packaging and storage in sequence to obtain the final EVA hot melt adhesive molded product.

[0049] Embodiment 2:

[0050] Based on the above embodiment 1, further description is given.

[0051] The viscosity of EVA hot melt adhesive at 120°C is 13000cps;

[0052] The volume resistivity of EVA hot melt adhesive is 4.8Ω*cm.

[0053] After testing, it was found that the conductive properties of EVA hot melt adhesive were effectively guaranteed while ensuring the effective viscosity value of the EVA hot melt adhesive.

[0054] The above is only a preferred specific implementation of the present invention; however, the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solution and its improved conception within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A process for preparing an EVA hot melt adhesive with excellent electrical conductivity, characterized in that: The specific implementation steps of the preparation process are as follows: Step 1: Select the raw materials. The specific raw materials are proportioned by mass as follows: The auxiliary agent includes one or more of a plasticizer, a stabilizer and an antioxidant, and the filler includes one or more of silica fume, talcum powder, aluminum powder and copper powder; The above raw materials are quantitatively weighed, dried and impurity-removed respectively to complete the configuration and pretreatment of the raw materials; Step 2: Put all the raw materials into the melting machine in sequence, melt and mix them to form a mixture. At this time, the melting conditions are controlled; Step 3: Extrude and filter the mixture to remove impurities, so that the mixture reaches a new storage container, and control the temperature of the storage container to ensure that the mixture is in a molten state; Step 4: quantitatively take the mixed material, inject the taken mixed material into the mold, control the temperature and wait for cooling to form a molded product; Step 5: Open the mold, take out the molded product, and then perform shaping, shearing, packaging and storage in sequence to obtain the final EVA hot melt adhesive molded product.

2. The process for preparing an EVA hot melt adhesive with excellent electrical conductivity according to claim 1, characterized in that: In the step 1, the selected raw materials include 120 parts of ethylene-vinyl acetate copolymer, 25 parts of tackifying resin, 12 parts of plasticizer, 8 parts of stabilizer, 1 part of antioxidant, 6 parts of silica fume, 5 parts of talc, 8 parts of aluminum powder, and 16 parts of copper powder.

3. The process for preparing an EVA hot melt adhesive with excellent electrical conductivity according to claim 2, characterized in that: Replace 16 parts of copper powder with a mixture of copper powder and silver powder, including 14 parts of copper powder and 2 parts of silver powder.

4. The process for preparing an EVA hot melt adhesive with excellent electrical conductivity according to claim 1, characterized in that: In the step 1, when the ethylene-vinyl acetate copolymer, the tackifying resin, the auxiliary agent and the filler are dried, a vacuum low-temperature drying method is adopted for drying.

5. The process for preparing an EVA hot melt adhesive with excellent electrical conductivity according to claim 1, characterized in that: In the step 1, during the impurity removal operation, the auxiliary agent and the filler are pulverized simultaneously, and at the same time, various components contained in the auxiliary agent are directly mixed evenly.

6. The process for preparing an EVA hot melt adhesive with excellent electrical conductivity according to claim 1, characterized in that: In the step 2, the temperature of the melter is first increased to 180° C., and then ethylene-vinyl acetate copolymer and tackifying resin are added and stirred until the two are evenly mixed, and then the mixture of the auxiliary agent and the mixture of the filler are added, and the temperature is increased again to 220-240° C., and stirring is continued for not less than 50 minutes until all the substances are evenly mixed.

7. The process for preparing an EVA hot melt adhesive with excellent electrical conductivity according to claim 1, characterized in that: In the step three, temperature detection is performed during extrusion and filtration and impurity removal, wherein the temperature during extrusion is not lower than 160° C., and the temperature during filtration and impurity removal is not lower than 130° C.

8. The process for preparing an EVA hot melt adhesive with excellent electrical conductivity according to claim 1, characterized in that: In the step 4, when the mixed material is injected into the mold, a funnel is used for injection, and at the same time, the mold is controlled to vibrate continuously at a low frequency.

9. The process for preparing an EVA hot melt adhesive with excellent electrical conductivity according to claim 1, characterized in that: In the step 4, during the cooling and molding process, the temperature is controlled to drop to 60° C. within 10 minutes, and then allowed to stand until the temperature reaches room temperature, and then allowed to stand for another 20 minutes.

10. The process for preparing an EVA hot melt adhesive with excellent electrical conductivity according to claim 1, characterized in that: The viscosity of EVA hot melt adhesive at 120°C is 13000cps; The volume resistivity of EVA hot melt adhesive is 4.8Ω*cm.

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