Strip-shaped heat-sealing cover tape adopting coating method and preparation method of strip-shaped heat-sealing cover tape

Abstract

The invention discloses a strip-shaped heat-sealing cover tape adopting a coating method and a preparation method of the strip-shaped heat-sealing cover tape, and belongs to the technical field of preparation of cover tapes for packaging electronic components. Comprising the following steps: mixing and stirring hydroxyl-terminated polydimethylsiloxane, diisocyanate, a dihydroxy ketone compound and a mixed solvent to form a mixed solution, heating the mixed solution to 80-90 DEG C through an organic tin catalyst, and carrying out polymerization reaction for 5-7 hours to obtain a polymerization solution; the polymerization liquid, a hydrazide compound, an antistatic agent and a dispersing agent are mixed and stirred to form a functional coating, and the functional coating is coated to a base material layer through a coating machine and naturally cured to obtain the heat-sealing cover tape. Hydroxyl-terminated polydimethylsiloxane with low surface energy, good light transmittance and low viscosity is used as a main raw material, after cross-linking polymerization, the hydroxyl-terminated polydimethylsiloxane, the hydrazide compound, the antistatic agent and the dispersing agent are mixed and stirred, then the base material layer is coated with the mixture, natural curing is conducted in the room temperature environment, and the heat sealing cover tape with the water absorption prevention performance is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of cover tapes for electronic component packaging, and in particular relates to a strip-shaped heat-sealed cover tape using a coating method and a preparation method thereof. Background Art

[0002] In the modern electronic manufacturing industry, the packaging and transportation of electronic components is a crucial link. There are many types of electronic components, including resistors, capacitors, transistors, diodes, etc. These components are easily affected by environmental factors such as dust, moisture, and static electricity during production, transportation, and storage, resulting in damage or performance degradation. Therefore, how to effectively protect these fragile electronic components has become a challenge that the electronic manufacturing industry must face. As an important material in the field of electronic packaging, cover tape plays a key role in protecting components, improving production efficiency, and reducing losses. Cover tape refers to a strip product used in the field of electronic packaging, which is mainly used in conjunction with carrier tape (carrier tape). Usually, the cover tape is made of polyester (PET) or polypropylene (PP) film as the base layer, and is compounded or coated with different functional layers, such as antistatic layer, adhesive layer, etc. Under external force or heating, the cover tape can be sealed on the surface of the carrier tape to form a closed space, thereby effectively protecting the electronic components in the carrier tape pocket. The base material of the cover tape is usually made of polyester (PET) or polypropylene (PP) film. These materials have good mechanical strength, wear resistance and chemical stability, and can effectively protect the internal components from the influence of the external environment. The functional layer of the cover tape is compounded or coated with various functional layers according to actual needs: (1) Antistatic layer: prevents static electricity from damaging electronic components and ensures their safety and reliability; (2) Adhesive layer: achieves a firm bond between the cover tape and the carrier tape, enhances the sealing effect, and prevents external contamination.

[0003] The functional layer of the cover tape is coated on the substrate layer by various methods including strip coating, interval coating or continuous coating, wherein strip coating is to evenly coat the functional layer coating on the substrate layer through the slit on the coating head, and then dry or cure to obtain the cover tape. Although drying and curing can remove moisture from the cover tape, when the humidity outside the material is greater than the humidity inside the material, the water molecules in the environment will produce directional movement under the action of the humidity difference and enter the material through the pores on the surface of the material. The higher the humidity and the higher the temperature in the environment, the faster the material absorbs moisture until the saturated moisture absorption rate is reached. When the cover tape material contains hydrophilic groups, water molecules will combine with the hydrophilic groups and be absorbed by the material, which can easily cause damage to electronic components due to moisture; and the surface and interior of the material contain a large number of micropores. Due to the presence of these tiny micropores, a capillary condensation effect will be produced on the moisture. This capillary effect makes the material with high porosity more likely to absorb moisture, thereby causing damage to the electronic components after heat sealing.

[0004] Therefore, designing a heat-sealing cover tape that can prevent water absorption is of great significance for improving the protection of electronic components after heat sealing. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention uses hydroxyl-terminated polydimethylsiloxane with low surface energy, good light transmittance and low viscosity as the main raw material, and then mixes and stirs it with a hydrazide compound, an antistatic agent and a dispersant after cross-linking polymerization, and then applies it to the substrate layer, and naturally solidifies it at room temperature to form a heat-sealed cover tape, which solves the technical problems raised in the background technology. Specifically, the technical solution of the present invention includes the following contents: One of the purposes of the present invention is to provide a method for preparing a strip-shaped heat-sealed cover tape by coating, the method comprising the following steps: The hydroxyl-terminated polydimethylsiloxane, diisocyanate, dihydroxy ketone compound and mixed solvent are mixed and stirred to form a mixed solution, and the mixed solution is heated to 80° C. to 90° C. with an organic tin catalyst for polymerization reaction for 5 h to 7 h to obtain a polymer solution; The polymer solution, hydrazide compound, antistatic agent and dispersant are mixed and stirred to form a functional coating, and the functional coating is applied to the substrate layer by a coating machine and naturally solidified to obtain a heat-sealed cover tape.

[0006] Furthermore, the dynamic viscosity of the hydroxyl-terminated polydimethylsiloxane is 40 mpa·s to 65 mpa·s.

[0007] Furthermore, the diisocyanate includes toluene diisocyanate, isophorone diisocyanate or hydrogenated MDI.

[0008] Furthermore, the dihydroxy ketone compound includes 1,3-dihydroxyacetone.

[0009] Furthermore, the mixed solvent is composed of bis(2-methoxyethyl) ether, dimethyl sulfoxide and deionized water in a weight ratio of 1:1:0.1.

[0010] Furthermore, the weight ratio of the hydroxyl-terminated polydimethylsiloxane: diisocyanate: dihydroxy ketone compound is 1: 0.3-0.5: 0.1-0.2.

[0011] Furthermore, the organic tin catalyst includes dibutyltin dilaurate.

[0012] Furthermore, the weight ratio of the mixed solution to the organic tin catalyst is 1:0.005-0.009.

[0013] Furthermore, the hydrazide compound includes maleic acid dihydrazide, adipic acid dihydrazide or sebacic acid dihydrazide.

[0014] Furthermore, the antistatic agent includes conductive carbon black.

[0015] Furthermore, the dispersant includes AEO-7 or AEO-9.

[0016] Furthermore, the substrate layer is polyethylene.

[0017] Furthermore, the weight ratio of the polymer solution: hydrazide compound: antistatic agent: dispersant is 1: 0.5-0.6: 0.02-0.05: 0.001-0.003.

[0018] A second object of the present invention is to provide a heat-sealing cover tape prepared by a method for preparing a heat-sealing cover tape by a strip coating method.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses hydroxyl-terminated polydimethylsiloxane with low surface energy, good light transmittance and low viscosity as the main raw material. Due to the dual effects of the main chain structure composed of alternating silicon (Si) and oxygen (O) in the structure and the hydrophobic side group structure (methyl, ethyl, etc.), polydimethylsiloxane has low surface energy properties. Low surface energy materials have a large water contact angle and are not easily wetted by water. Subsequently, with the help of the condensation polymerization of the diisocyanate structure and the hydroxyl group, the diisocyanate is used as a cross-linking agent to polymerize the dihydroxy ketone compound with the hydroxyl-terminated polydimethylsiloxane, thereby introducing the ketone structure into the structure of the hydroxyl-terminated polydimethylsiloxane, and then obtaining a polymer solution containing the ketone structure. Subsequently, the polymer solution is mixed with a hydrazide compound having a hydrazide structure, an antistatic agent with antistatic function, and a dispersant to form a functional coating. The functional coating is applied to the polyethylene surface of the substrate layer by a coating machine to form a heat-sealing cover tape. When the heat-sealing cover tape is not used for heat sealing, the ketone group and the hydrazide group are poorly cross-linked in the aqueous system and the water generated by the cross-linking is difficult to remove. The weak cross-linking leads to low viscosity. After high-temperature heat sealing treatment, the heat-sealing cover tape promotes the formation of ketone-hydrazide cross-linking due to the evaporation of water, obtains good viscosity, and achieves sealing between the carrier tape, thereby protecting the electronic components. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be clearly and completely described below through 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 those skilled in the art without creative work are within the scope of protection of the present invention.

[0021] Unless otherwise specified, the raw materials and reagents used in the present invention are commercially available or can be prepared by known methods.

[0022] Embodiment 1: A method for preparing a strip-shaped heat-sealed cover tape by coating method, specifically comprising the following steps: 1 part by weight of hydroxyl-terminated polydimethylsiloxane with a dynamic viscosity of 40 mpa·s, 0.3 parts by weight of toluene diisocyanate, 0.1 parts by weight of 1,3-dihydroxyacetone and 1 part by weight of a mixed solvent (mixed and stirred evenly by bis(2-methoxyethyl)ether, dimethyl sulfoxide and deionized water in a weight ratio of 1:1:0.1) were weighed and placed in a reactor and stirred evenly to obtain a mixed solution, and 0.005 times the weight of the mixed solution of dibutyltin dilaurate catalyst was added to the mixed solution and mixed and stirred, and the temperature was raised to 80°C for reaction for 5 hours. After the reaction, the obtained polymer solution, maleic acid dihydrazide, conductive carbon black and AEO-7 were mixed in a weight ratio of 1:0.5:0.02:0.001 and stirred at a speed of 200 r / min until the conductive carbon black was evenly dispersed to obtain a functional coating. The functional coating was coated on the surface of the polyethylene substrate by a coating machine, and then naturally cured at room temperature to obtain a heat-sealed cover tape.

[0023] Embodiment 2: A method for preparing a strip-shaped heat-sealed cover tape by coating method, specifically comprising the following steps: 1 part by weight of hydroxyl-terminated polydimethylsiloxane with a dynamic viscosity of 45 mpa·s, 0.3 part by weight of toluene diisocyanate, 0.12 part by weight of 1,3-dihydroxyacetone and 1.1 part by weight of a mixed solvent (bis(2-methoxyethyl)ether, dimethyl sulfoxide and deionized water were mixed and stirred in advance in a weight ratio of 1:1:0.1 for standby use) were placed in a reactor and stirred to obtain a mixed solution. 0.006 times the weight of the mixed solution of dibutyltin dilaurate catalyst was added to the mixed solution and mixed and stirred, and the temperature was raised to 80°C for reaction for 5 hours. After the reaction, the obtained polymer solution, maleic acid dihydrazide, conductive carbon black and AEO-7 were mixed in a weight ratio of 1:0.52:0.03:0.001 and stirred at a speed of 200 r / min until the conductive carbon black was evenly dispersed to obtain a functional coating. The functional coating was coated on the surface of the polyethylene substrate by a coating machine, and then naturally cured at room temperature to obtain a heat-sealed cover tape.

[0024] Embodiment 3: A method for preparing a strip-shaped heat-sealed cover tape by coating method, specifically comprising the following steps: 1 part by weight of hydroxyl-terminated polydimethylsiloxane with a dynamic viscosity of 50 mpa·s, 0.4 part by weight of isophorone diisocyanate, 0.14 part by weight of 1,3-dihydroxyacetone and 1.2 parts by weight of a mixed solvent (bis(2-methoxyethyl)ether, dimethyl sulfoxide and deionized water are mixed and stirred in advance in a weight ratio of 1:1:0.1 for standby use) are placed in a reactor and stirred to obtain a mixed solution. 0.007 times the weight of the mixed solution of dibutyltin dilaurate catalyst is added to the mixed solution and mixed and stirred, and the temperature is raised to 85°C for reaction for 6 hours. After the reaction is completed, the obtained polymer solution, adipic acid dihydrazide, conductive carbon black and AEO-7 are mixed in a weight ratio of 1:0.54:0.03:0.002 and stirred at a speed of 200 r / min until the conductive carbon black is evenly dispersed to obtain a functional coating. The functional coating is coated on the surface of the polyethylene substrate by a coating machine, and then naturally cured at room temperature to obtain a heat-sealed cover tape.

[0025] Embodiment 4: A method for preparing a strip-shaped heat-sealed cover tape by coating method, specifically comprising the following steps: 1 part by weight of hydroxyl-terminated polydimethylsiloxane with a dynamic viscosity of 55 mpa·s, 0.4 part by weight of isophorone diisocyanate, 0.16 part by weight of 1,3-dihydroxyacetone and 1.3 parts by weight of a mixed solvent (bis(2-methoxyethyl) ether, dimethyl sulfoxide and deionized water are mixed and stirred in advance in a weight ratio of 1:1:0.1 for standby use) are placed in a reactor and stirred to obtain a mixed solution. 0.008 times the weight of the mixed solution of dibutyltin dilaurate catalyst is added to the mixed solution and mixed and stirred, and the temperature is raised to 85°C for reaction for 6 hours. After the reaction is completed, the obtained polymer solution, adipic acid dihydrazide, conductive carbon black and AEO-9 are mixed in a weight ratio of 1:0.56:0.04:0.002 and stirred at a speed of 300 r / min until the conductive carbon black is evenly dispersed to obtain a functional coating. The functional coating is coated on the surface of the polyethylene substrate by a coating machine, and then naturally cured at room temperature to obtain a heat-sealed cover tape.

[0026] Embodiment 5: A method for preparing a strip-shaped heat-sealed cover tape by coating method, specifically comprising the following steps: 1 part by weight of hydroxyl-terminated polydimethylsiloxane with a dynamic viscosity of 60 mpa·s, 0.5 part by weight of hydrogenated MDI, 0.18 part by weight of 1,3-dihydroxyacetone and 1.4 parts by weight of a mixed solvent (bis(2-methoxyethyl)ether, dimethyl sulfoxide and deionized water were mixed and stirred in advance in a weight ratio of 1:1:0.1 for standby use) were placed in a reactor and stirred to obtain a mixed solution. 0.009 times the weight of the mixed solution of dibutyltin dilaurate catalyst was added to the mixed solution and mixed and stirred, and the temperature was raised to 90°C for reaction for 7 hours. After the reaction, the obtained polymer solution, sebacic acid dihydrazide, conductive carbon black and AEO-9 were mixed in a weight ratio of 1:0.58:0.04:0.003 and stirred at a speed of 300 r / min until the conductive carbon black was evenly dispersed to obtain a functional coating. The functional coating was coated on the surface of the polyethylene substrate by a coating machine, and then naturally cured at room temperature to obtain a heat-sealed cover tape.

[0027] Embodiment 6: A method for preparing a strip-shaped heat-sealed cover tape by coating method, specifically comprising the following steps: 1 part by weight of hydroxyl-terminated polydimethylsiloxane with a dynamic viscosity of 65 mpa·s, 0.5 part by weight of hydrogenated MDI, 0.2 part by weight of 1,3-dihydroxyacetone and 1.5 parts by weight of mixed solvent (bis(2-methoxyethyl) ether, dimethyl sulfoxide and deionized water were mixed and stirred in advance in a weight ratio of 1:1:0.1 for standby use) were placed in a reactor and stirred to obtain a mixed solution. 0.009 times the weight of the mixed solution of dibutyltin dilaurate catalyst was added to the mixed solution and mixed and stirred, and the mixture was heated to 90°C for reaction for 7 hours. After the reaction, the obtained polymer solution, sebacic acid dihydrazide, conductive carbon black and AEO-9 were mixed in a weight ratio of 1:0.6:0.05:0.003 and stirred at a speed of 300 r / min until the conductive carbon black was evenly dispersed to obtain a functional coating. The functional coating was coated on the surface of the polyethylene substrate by a coating machine, and then naturally cured at room temperature to obtain a heat-sealed cover tape.

[0028] Comparative Example 1: A method for preparing a strip-shaped heat-sealed cover tape by coating method, specifically comprising the following steps: The hydroxyl-terminated polydimethylsiloxane in Example 6 was replaced with a hydroxyl-terminated polydimethylsiloxane with a dynamic viscosity of 1500 mPa·s, and the other conditions were the same as those in Example 6. It was found that it was difficult to mix uniformly during the preparation of the mixed solution, which may be due to the poor fluidity of the hydroxyl-terminated polydimethylsiloxane with too high a dynamic viscosity, which made it difficult to disperse in the mixed system of the present invention and the preparation failed.

[0029] Comparative Example 2: A method for preparing a strip-shaped heat-sealed cover tape by coating method, specifically comprising the following steps: The hydroxyl-terminated polydimethylsiloxane in Example 6 was replaced with a hydroxyl-terminated polydimethylsiloxane with a dynamic viscosity of 200 mPa·s, and the other conditions were the same as those in Example 6. During the coating process of the coating machine, it was found that the coating failed, and the functional coating had a strong viscosity, which resulted in the inability to be evenly dispersed on the surface of the polyethylene substrate, resulting in coating failure.

[0030] Comparative Example 3: A method for preparing a strip-shaped heat-sealed cover tape by coating method, specifically comprising the following steps: The sebacic acid dihydrazide in Example 6 was replaced by benzoyl hydrazide, and the other conditions were kept the same as those in Example 6.

[0031] Comparative Example 4: A method for preparing a strip-shaped heat-sealed cover tape by coating method, specifically comprising the following steps: The deionized water of the mixed solvent in Example 6 was removed and not added, and the other conditions remained the same as in Example 6.

[0032] test: The heat-sealing cover tapes obtained in Examples 1 to 6 and Comparative Examples 3 to 4 were attached to the carrier tape, and then sealed at a heat-sealing temperature of 90±5° C.: The light transmittance and haze of the heat-sealed cover tape were measured according to the standard "ASTM-D1003 Test method for light transmittance and haze of transparent plastics". The results are shown in Table 1 below.

[0033] Table 1 Optical properties The heat-sealed cover tape was peeled off at a pulling speed of 300 mm / min and the peel strength (N / 15 mm) was recorded. The results are shown in Table 2 below.

[0034] Table 2 Peel strength The surface resistance of the heat-sealed cover tape was measured according to GB / T33398 2016. The results are shown in Table 3.

[0035] Table 3 Surface resistance The heat-sealed cover tape was cut into squares, then immersed in a water bath at 35±2°C for 24 hours, and then the surface moisture was removed and dried. The water absorption rate was taken as the ratio of the weight after water absorption minus the weight before water absorption to the weight before water absorption. The results are shown in Table 4.

[0036] Table 4 Water absorption The following conclusions can be drawn from the test results in Tables 1 to 4 above: (1) It can be found from Examples 1 to 6 that in the preparation system of the present invention, hydroxyl-terminated polydimethylsiloxane with low surface energy, good light transmittance and low viscosity is used as the main raw material, which is mixed and stirred with a hydrazide compound, an antistatic agent and a dispersant after cross-linking polymerization and then coated on the substrate layer, and naturally solidified at room temperature to form a heat-sealed cover tape. After high-temperature heat sealing, the cover tape not only has good anti-water absorption performance, but also better retains the optical properties of the polydimethylsiloxane material, and has good peel strength and antistatic performance.

[0037] (2) Comparative Example 3 shows that although benzoyl hydrazide also has a hydrazine structure that can cross-link with a ketone group, it also contains a benzene ring, resulting in a larger number of benzene rings being introduced into the cross-linked structure. The rigid structure of the benzene ring makes it possible for the heat-sealed cover tape to be too strong after high-temperature heat sealing, resulting in breakage during the peeling process, and easily generating debris that is transferred into the carrier tape, affecting the use of electronic components.

[0038] (3) It can be found from Comparative Example 4 that although the presence of deionized water does not have much influence on the early preparation of the polymer solution, due to the lack of water barrier when it is mixed and dispersed with the hydrazide compound sebacic acid dihydrazide in the later stage, the obtained functional coating has a certain viscosity when it is not heat-sealed, which is not conducive to the winding and storage of the cover tape after drying. Therefore, in actual use, it is necessary to additionally adhere a third substrate to the other side of the functional coating coated on the substrate to prevent adhesion generated during winding.

[0039] The above-described embodiments provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected.

Claims

1. A method for preparing a strip-shaped heat-sealed cover tape by coating, characterized in that: The preparation method comprises the following steps: The hydroxyl-terminated polydimethylsiloxane, diisocyanate, dihydroxy ketone compound and mixed solvent are mixed and stirred to form a mixed solution, and the mixed solution is heated to 80° C. to 90° C. with an organic tin catalyst for polymerization reaction for 5 h to 7 h to obtain a polymer solution; The polymer solution, hydrazide compound, antistatic agent and dispersant are mixed and stirred to form a functional coating, and the functional coating is applied to the substrate layer by a coating machine and naturally solidified to obtain a heat-sealed cover tape.

2. The method for preparing a strip-shaped heat-sealed cover tape by coating method according to claim 1, characterized in that: The hydroxyl-terminated polydimethylsiloxane has a dynamic viscosity of 40 mpa·s to 65 mpa·s.

3. The method for preparing a strip-shaped heat-sealed cover tape by coating method according to claim 1, characterized in that: The diisocyanate includes toluene diisocyanate, isophorone diisocyanate or hydrogenated MDI.

4. The method for preparing a strip-shaped heat-sealed cover tape by coating method according to claim 1, characterized in that: The dihydroxy ketone compound includes 1,3-dihydroxyacetone.

5. The method for preparing a strip-shaped heat-sealed cover tape by coating method according to claim 1, characterized in that: The mixed solvent is composed of bis(2-methoxyethyl) ether, dimethyl sulfoxide and deionized water in a weight ratio of 1:1:0.

1.

6. The method for preparing a strip-shaped heat-sealed cover tape by coating method according to claim 1, characterized in that: The weight ratio of the hydroxyl-terminated polydimethylsiloxane: diisocyanate: dihydroxy ketone compound is 1: 0.3-0.5: 0.1-0.

2.

7. The method for preparing a strip-shaped heat-sealed cover tape by coating method according to claim 1, characterized in that: The weight ratio of the mixed solution to the organic tin catalyst is 1:0.005-0.

009.

8. The method for preparing a strip-shaped heat-sealed cover tape by coating method according to claim 1, characterized in that: The hydrazide compound includes maleic acid dihydrazide, adipic acid dihydrazide or sebacic acid dihydrazide.

9. The method for preparing a strip-shaped heat-sealed cover tape by coating method according to claim 1, characterized in that: The weight ratio of the polymer solution: hydrazide compound: antistatic agent: dispersant is 1: 0.5-0.6: 0.02-0.05: 0.001-0.

003.

10. A heat-sealing cover tape prepared by the method for preparing a strip-shaped heat-sealing cover tape by a coating method according to any one of claims 1 to 9.

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