A hot-melt composition, a heat-sealing layer containing the hot-melt composition, and a cover tape

Abstract

The present invention belongs to the technical field of packaging materials for electronic components. Specifically, it relates to a hot-melt composition, a heat-sealing layer containing the hot-melt composition, and a cover tape. The hot-melt composition includes a mixture of 50-85 wt% of a vinyl ester copolymer and a vinyl acid copolymer, 5-25 wt% of a tackifying resin, 3-15 wt% of an anti-tack resin, 1-8 wt% of anti-tack particles, and 0.1-2 wt% of an antioxidant. By using the above hot-melt composition to form the heat-sealing layer of the cover tape, the cover tape can have good adhesiveness, stable peel strength, excellent peelability, and anti-sticking property after being sealed to a paper carrier tape.

Description

Technical Field

[0001] The present invention belongs to the technical field of packaging materials for electronic components. Specifically, it is a hot-melt composition, a heat-sealing layer containing the hot-melt composition, and a cover tape. Background Art

[0002] In order to adapt to the development of automation and high speed in the encapsulation of electronic components, electronic components are usually stored in the receiving holes of a carrier tape. The carrier tape is formed by equidistantly forming receiving holes adapted to the shape of the electronic components and circular traction holes at certain intervals on a long strip-shaped substrate. After the electronic components are received in the receiving holes, a cover tape is covered and then wound into a roll to form an electronic component package. Generally, the substrate of the carrier tape can be selected from PS, PET, PC, ABS, or paper-based, and the cover tape is usually formed by laminating a heat-sealing layer made of a hot-melt composition on a polyester film substrate.

[0003] In recent years, the miniaturization, light weight, and thinness of various electronic components such as capacitors, resistors, ICs, LEDs, and connectors have been significantly developed. For microelectronic components, paper carrier tapes are often used for storage. At this time, when the electronic components are taken out of the package and the cover tape is peeled off, higher requirements are imposed on the peeling stability and peeling debris of the cover tape. In addition, when the electronic component package is stored and transported in a rolled form, changes in the storage environment and transportation conditions, especially under high temperature and high temperature and high humidity, often result in sticking of materials, that is, the electronic components adhere to the cover tape when the cover tape is peeled off, causing the pick-and-place equipment to be unable to pick up smoothly.

[0004] It has been found through research that the performance of the hot-melt adhesive used to make the heat-sealing layer of the cover tape plays a decisive role in the above-mentioned performance of the cover tape. Therefore, more and more research has been conducted on the hot-melt adhesive of the heat-sealing layer of the cover tape.

[0005] For example, the invention patent application with the publication number CN104212381 A discloses a hot-melt adhesive for producing resistor tapes, which is composed of 22-27 parts by weight of low-density polyethylene, 42-47 parts by weight of ethylene-vinyl acetate copolymer, 0.5-1.0 part by weight of oleic acid amide, 0.2-0.6 part by weight of stearic acid amide, 0.1-0.6 part by weight of silicon oxide, 37-42 parts by weight of resin tackifier, and 17-23 parts by weight of high molecular antistatic agent.

[0006] However, when using the above heat-sealing cover tape or the cover tape with a heat-sealing layer made of the above hot-melt adhesive, there are still problems such as unstable peeling strength, more pulling debris, adhesion of electronic components, and unwinding adhesion.

[0007] Some prior arts have also disclosed adhesive resin compositions that can be used for carrier tapes. For example, the adhesive resin in CN113677771A includes an ethylene-vinyl acetate copolymer (A). The content of the structural unit derived from vinyl acetate in the ethylene-vinyl acetate copolymer (A) is 3% by mass or more and 18% by mass or less, and the melt mass flow rate is 5 g / 10 min or more and 40 g / 10 min or less; a tackifying resin (B); and an ethylene-vinyl acetate copolymer (C). The viscosity of the ethylene-vinyl acetate copolymer (C) measured at 180 °C using a Brookfield viscometer is 15,000 mPa·s or more and 300,000 mPa·s or less.

[0008] The adhesive resin in CN107207927A includes an ethylene unsaturated carboxylic acid ester copolymer A. The content of the structural unit derived from the unsaturated carboxylic acid ester in the ethylene unsaturated carboxylic acid ester copolymer A is greater than 0% by mass and less than 10% by mass; an ethylene unsaturated carboxylic acid ester copolymer B. The content of the structural unit derived from the unsaturated carboxylic acid ester in the ethylene unsaturated carboxylic acid ester copolymer B is 10% by mass or more and 40% by mass or less; a resin C. The resin C is at least incompatible with the above-mentioned ethylene-unsaturated carboxylic acid ester copolymer A.

[0009] The cover film made of the above two adhesive resins can achieve good sealing and easy peelability with the paper substrate. However, there are still certain defects. Especially in high-temperature and high-temperature high-humidity environments, adhesion between electronic components and the cover tape is likely to occur, and there are many lint during peeling. Summary of the Invention

[0010] To solve the above problems, the present invention improves the components of the hot melt adhesive to obtain a hot melt composition for the heat-sealing layer of the cover tape. After being sealed with the paper carrier tape, it has a stable peel strength. In high-temperature and high-temperature high-humidity environments, there are few lint when pulled up. Even for microelectronic components, they will not adhere to it, and the cover tape itself will not unwind and stick.

[0011] Specifically, the present invention adopts the following technical solutions:

[0012] A hot melt composition for the heat-sealing layer of a cover tape includes a mixture of 50-85 wt% of a vinyl ester copolymer and a vinyl acid copolymer, 5-25 wt% of a tackifying resin, 3-15 wt% of an anti-sticking resin, 1-8 wt% of anti-sticking particles, and 0.1-2 wt% of an antioxidant.

[0013] As a preference of the above technical solution, the ratio of the vinyl ester copolymer to the vinyl acid copolymer is in the range of 60-80:20-40, preferably 70:30, and more preferably 80:20.

[0014] As a preference of the above technical solution, the vinyl ester copolymer includes one or more of ethylene-vinyl acetate, ethylene-methyl acrylate, ethylene-methyl methacrylate, ethylene-ethyl acrylate, and ethylene-butyl acrylate.

[0015] As a preference of the above technical solution, the content of the ester monomer in the vinyl ester copolymer ranges from 5% to 30%, preferably from 6% to 20%, and more preferably from 8% to 15%.

[0016] As a preference of the above technical solution, the vinyl acid copolymer includes one or more of ethylene-methacrylic acid copolymer, ethylene-acrylic acid copolymer, and ethylene-acrylic acid-maleic anhydride copolymer.

[0017] As a preference of the above technical solution, the content of the acid monomer in the vinyl acid copolymer is 2% to 30%, preferably 4% to 25%, and more preferably 6% to 20%.

[0018] As a preference of the above technical solution, the ring and ball softening point of the tackifying resin is 100°C to 140°C.

[0019] As a preference of the above technical solution, the tackifying resin can be one or two of hydrogenated rosin resin, C5 resin, C9 resin, hydrogenated C5 resin, hydrogenated C9 resin, and hydrogenated C5 / C9 copolymer resin.

[0020] As a preference of the above technical solution, the anti-sticking resin can be one or two of α-methylstyrene, maleic anhydride grafted high density polyethylene, styrene maleic anhydride copolymer, and phenyl maleimide copolymer.

[0021] As a preference of the above technical solution, the anti-sticking resin is maleic anhydride grafted high density polyethylene and styrene maleic anhydride copolymer. Due to the introduction of maleic anhydride groups, the polarity of the molecule is increased, the stability of the hot melt composition at high temperature and high temperature and high humidity is improved, the sticking rate is reduced, and at the same time, since its own structure is still mainly based on the polyolefin main chain, it has good compatibility with the mixture of vinyl ester copolymer and vinyl acid copolymer.

[0022] As a preference of the above technical solution, the anti-sticking particles are one or more of inorganic particles, fatty amide particles, and silicone masterbatch.

[0023] As a preference of the above technical solution, the inorganic particles are one or more of silica particles, talcum powder, calcium carbonate, barium sulfate, kaolin, etc.

[0024] As a preference of the above technical solution, the fatty amide particles are oleic acid amide, erucic acid amide, EBS, etc.

[0025] The present invention also provides a heat-sealing layer for a cover tape, which contains the above-mentioned hot-melt composition.

[0026] The present invention also provides a cover tape, which contains the above-mentioned heat-sealing layer.

[0027] The cover tape at least includes a substrate layer and a heat-sealing layer formed on the substrate layer. The cover tape may also contain other layers, such as an antistatic layer formed on the heat-sealing layer, a buffer layer formed between the substrate layer and the heat-sealing layer, etc. Among them, the heat-sealing layer is made of the above-mentioned hot-melt composition, and its thickness is 5-25 μm. The substrate layer is BOPET, and its thickness is 15-40 μm. The buffer layer is made of LDPE, and its thickness is 5-30 μm. The antistatic layer is made by coating quaternary ammonium salts or conductive liquids.

[0028] By implementing the above technical solutions, the present invention has the following advantages:

[0029] 1. By using the above-mentioned hot-melt composition to make the heat-sealing layer of the cover tape, after the cover tape is sealed to the paper carrier tape, it has good adhesiveness, stable peel strength, excellent peelability and anti-sticking property;

[0030] 2. By using the above-mentioned hot-melt composition to make the heat-sealing layer of the cover tape, after the cover tape is sealed to the paper carrier tape, even under high temperature and high temperature and high humidity conditions, there are few pulled-up hairs, and it can maintain a low adhesive rate for microelectronic components.

[0031] 3. By using the above-mentioned hot-melt composition to make the heat-sealing layer of the cover tape, the cover tape itself will not unwind and stick, and the heat-sealing layer has excellent molding stability, small necking and is not easy to break the edge. Specific Embodiments

[0032] The following is an illustration of the preferred embodiments of the present invention, which further describes the technical solutions of the present invention. However, the following embodiments are only the preferred embodiments of the present invention and do not limit the present invention.

[0033] The hot-melt composition provided by the present invention includes a mixture of 50-85 wt% of a vinyl ester copolymer and a vinyl acid copolymer, 5-25 wt% of a tackifying resin, 3-15 wt% of an anti-adhesive resin, 1-8 wt% of anti-adhesive particles, and 0.1-2 wt% of an antioxidant.

[0034] Mixture of vinyl ester copolymer and vinyl acid copolymer

[0035] The mixture of the vinyl ester copolymer and the vinyl acid copolymer is the main component for the hot-melt composition to achieve bonding performance, and its content is between 50 and 85 wt%. By mixing the vinyl ester copolymer and the vinyl acid copolymer in a specific ratio as the main component, the present invention improves the peel stability, which is beneficial to the peel performance and anti-sticking performance of the heat-sealing layer.

[0036] In the mixture of the two, the ratio of the vinyl ester copolymer to the vinyl acid copolymer also affects the performance of the heat-sealing layer. The ratio of the vinyl ester copolymer to the vinyl acid copolymer is in the range of 60 to 80:20 to 40, preferably 70:30, and more preferably 80:20. The above mixture provides appropriate viscosity for the hot-melt composition. Comparatively speaking, the vinyl acid copolymer provides higher viscosity. When the ratio of the vinyl ester copolymer to the vinyl acid copolymer is within the above range, the hot-melt composition will neither have excessive viscosity, resulting in easy generation of lint during the peeling of the cover tape and difficulty in processing, nor have insufficient viscosity, unable to provide reliable peel strength, resulting in easy detachment of the cover tape during the transportation of the electronic component package. In addition, when the ratio of the vinyl ester copolymer to the vinyl acid copolymer in the mixture is within the above range, the molecular weight distribution of the composition is wide, with a large number of long branches, making the forming stability of the heat-sealing layer excellent, with small necking and not easy to break the edge.

[0037] The vinyl ester copolymer includes one or more of ethylene-vinyl acetate, ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate, ethylene-ethyl acrylate, and ethylene-butyl acrylate. In the mixture of the vinyl ester copolymer and the vinyl acid copolymer, the content of the ester monomer in the vinyl ester copolymer is in the range of 5 to 30%, preferably 6 to 20%, and more preferably 8 to 15%. If the content of the ester monomer is less than 5%, the viscosity of the hot-melt composition is insufficient, unable to provide reliable peel strength, and the cover tape made is likely to fall off during the transportation of the electronic component package. If the content of the ester monomer is higher than 30%, the viscosity of the hot-melt composition is too strong, and lint is likely to be generated during the peeling of the cover tape.

[0038] The vinyl acid copolymers include one or more of ethylene-methacrylic acid copolymer, ethylene-acrylic acid copolymer, and ethylene-acrylic acid-maleic anhydride copolymer. The content of the acid monomer in the vinyl acid copolymers ranges from 2% to 30%, preferably from 4% to 25%, and more preferably from 6% to 20%. If the content of the acid monomer is less than 2%, the viscosity of the hot melt composition is insufficient to provide reliable peel strength, and the resulting cover tape is likely to fall off during the transportation of the electronic component package. If the content of the acid monomer is higher than 30%, the viscosity of the hot melt composition is too strong, and it is easy to generate lint during the peeling of the cover tape, and there are also problems with difficult processing.

[0039] Tackifying resin

[0040] The tackifying resin is used to cooperate with the mixture of the vinyl ester copolymer and the vinyl acid copolymer to provide excellent adhesion performance for the hot melt composition. The tackifying resin can be one or two of hydrogenated rosin resin, C5 resin, C9 resin, hydrogenated C5 resin, hydrogenated C9 resin, and hydrogenated C5 / C9 copolymer resin. The ring and ball softening point of the tackifying resin is between 100°C and 140°C. If the softening point of the tackifying resin is lower than 100°C, it is easy to cause sticking of electronic components, and there are also problems with difficult processing. If the softening point of the tackifying resin is higher than 140°C, it is difficult to obtain reliable viscosity, and the resulting cover tape is likely to fall off during the transportation of the electronic component package.

[0041] Anti-sticking resin

[0042] The anti-sticking resin can further reduce the sticking rate of the cover tape at high temperature and high temperature and high humidity. The anti-sticking resin can be one or two of α-methylstyrene, maleic anhydride grafted high-density polyethylene, styrene maleic anhydride copolymer, and phenyl maleimide copolymer. Due to the presence of a large number of rigid structures in the molecular structure of the above anti-sticking resin, the steric hindrance of the molecule is changed, and it has a relatively high glass transition temperature. When added to the hot melt composition, it increases the Vicat softening point of the composition. At high temperature and high temperature and high humidity, the hot melt composition will not soften and the viscosity will not increase, reducing the sticking rate of the cover tape. The preferred anti-sticking resins are maleic anhydride grafted high-density polyethylene and styrene maleic anhydride copolymer. Due to the introduction of maleic anhydride groups, the polarity of the molecule is increased, the stability of the hot melt composition at high temperature and / or high humidity is improved, and the sticking rate is reduced. At the same time, because its own structure is still mainly based on the polyolefin main chain, it has good compatibility with the mixture of vinyl ester copolymer and vinyl acid copolymer.

[0043] Anti-sticking particles

[0044] The anti-sticking particles increase the surface roughness of the heat-sealing layer, preventing the cover tape from unrolling and sticking. The anti-sticking particles can be inorganic particles such as silica particles, talcum powder, calcium carbonate, barium sulfate, kaolin, etc., or fatty amide particles such as oleic acid amide, erucic acid amide, EBS, etc., or silicone masterbatch.

[0045] Antioxidant

[0046] The antioxidants are general-purpose antioxidants 1010 and 168. The addition ratio of the two is antioxidant 1010 / antioxidant 168 = 2:1, which can improve the anti-aging performance of the hot-melt composition under high-temperature processing, and under high-temperature and high-temperature high-humidity conditions of the cover tape.

[0047] Example 1

[0048] This example provides a hot-melt composition for the heat-sealing layer of a paper carrier tape cover tape. The specific composition and content are as follows:

[0049] A mixture of 67.7 wt% of vinyl ester copolymer and vinyl acid copolymer, 15 wt% of tackifying resin, 15 wt% of anti-sticking resin, 2 wt% of anti-sticking particles, and 0.3 wt% of antioxidant.

[0050] Among them, the ratio of vinyl ester copolymer to vinyl acid copolymer is 60:40. The vinyl ester copolymer is ethylene-vinyl acetate, and the ester monomer content is 9%. The vinyl acid copolymer is ethylene-acrylic acid copolymer, and the acid monomer content is 6%.

[0051] The tackifying resin is hydrogenated rosin resin, the anti-sticking resin is α-methylstyrene, and the anti-sticking particles are silica particles. The antioxidant is a mixture of antioxidant 1010 and antioxidant 168, and the mixing mass ratio of the two is 2:1.

[0052] Example 2

[0053] This example provides a hot-melt composition for the heat-sealing layer of a paper carrier tape cover tape. The specific composition and content are as follows:

[0054] A mixture of 76.8 wt% of vinyl ester copolymer and vinyl acid copolymer, 10 wt% of tackifying resin, 8 wt% of anti-sticking resin, 5 wt% of anti-sticking particles, and 0.2 wt% of antioxidant.

[0055] Among them, the ratio of vinyl ester copolymer to vinyl acid copolymer is 70:30. The vinyl ester copolymer is ethylene-methyl methacrylate, and the ester monomer content is 18%. The vinyl acid copolymer is ethylene-methyl acrylic acid copolymer, and the acid monomer content is 8%.

[0056] The tackifying resin uses hydrogenated C9 resin, the anti-sticking resin uses maleic anhydride grafted high-density polyethylene, and the anti-sticking particles use silicone masterbatch. The antioxidant uses a mixture of antioxidant 1010 and antioxidant 168, and the mixing mass ratio of the two is 2:1.

[0057] Example 3

[0058] This example provides a hot-melt composition for the heat-sealing layer of a paper carrier tape cover tape. The specific composition and content are as follows:

[0059] A mixture of 61.7 wt% of vinyl ester copolymer and vinyl acid copolymer, 20 wt% of tackifying resin, 15 wt% of anti-sticking resin, 3 wt% of anti-sticking particles, and 0.3 wt% of antioxidant.

[0060] Among them, the ratio of vinyl ester copolymer to vinyl acid copolymer is 80:20. The vinyl ester copolymer uses ethylene-butyl acrylate, and the ester monomer content is 15%. The vinyl acid copolymer uses ethylene-methacrylic acid copolymer, and the acid monomer content is 20%.

[0061] The tackifying resin uses hydrogenated C5 resin, the anti-sticking resin uses styrene maleic anhydride copolymer, and the anti-sticking particles use talcum powder. The antioxidant uses a mixture of antioxidant 1010 and antioxidant 168, and the mixing mass ratio of the two is 2:1.

[0062] Comparative Example 1:

[0063] The difference from Example 1 is that it does not contain vinyl acid copolymer. The specific composition and content are as follows: 67.7% of vinyl ester copolymer, 15 wt% of tackifying resin, 15 wt% of anti-sticking resin, 2 wt% of anti-sticking particles, and 0.3 wt% of antioxidant. The vinyl ester copolymer uses ethylene-vinyl acetate, and the ester monomer content is 9%.

[0064] Comparative Example 2:

[0065] The difference from Example 1 is that it does not contain vinyl ester copolymer. The specific composition and content are as follows: 67.7% of vinyl acid copolymer, 15 wt% of tackifying resin, 15 wt% of anti-sticking resin, 2 wt% of anti-sticking particles, and 0.3 wt% of antioxidant. The vinyl acid copolymer uses ethylene-acrylic acid copolymer, and the acid monomer content is 6%.

[0066] Comparative Example 3:

[0067] The difference from Example 1 is that the ratio of vinyl ester copolymer to vinyl acid copolymer is 50:50.

[0068] Comparative Example 4:

[0069] It is different from Example 1 in that the ratio of the vinyl ester copolymer to the vinyl acid copolymer is 40:60.

[0070] Application Example

[0071] This application example provides a cover tape for a paper carrier tape of electronic components, which is composed of a substrate layer, a buffer layer, a heat-sealing layer, and an antistatic layer. Among them, the heat-sealing layer is formed by extrusion and compounding of the hot-melt compositions of Examples 1 to 3 and Comparative Examples 1 to 4, and its thickness is 15 μm. The substrate layer of the cover tape is made of BOPET, and its thickness is 30 μm. The buffer layer is made of LDPE, and its thickness is 15 μm. The antistatic layer is formed by coating and drying a quaternary ammonium salt-based conductive liquid.

[0072] The relevant test data of the cover tapes corresponding to each example and comparative example are as follows. The test items, test methods, and test results are as follows.

[0073] Test Method

[0074] Peel Strength Test:

[0075] The cover tapes corresponding to the above examples and comparative examples were cut into a width of 5.25 mm and heat-sealed on a 42 mm thick paper carrier tape according to the following heat-sealing conditions (heat-sealing temperature: 190 °C, heat-sealing pressure: 2 - 3 Mpa, heat-sealing speed: 3300 pcs / min).

[0076] Using a peel strength test device, peel at a speed of 300 mm / min and an angle of 165°, and read the peel strength data. The peel strength difference (R) less than 20 is qualified.

[0077] Pull-up Fluff Test:

[0078] Lay the above-mentioned heat-sealed sample tape flat, peel at an angle of 60°, and then observe the amount of fluff attached to the surface of the cover tape.

[0079] ○ indicates that there is no block fluff greater than 1 cm or fluff appears on the cover tape continuously for 2 cm (qualified); ◎ indicates no fluff (optimal); ╳ indicates the existence of block fluff greater than 1 cm or fluff appears on the cover tape continuously for 2 cm (unqualified);

[0080] Adhesive Rate Test:

[0081] The cover tapes corresponding to the above-mentioned examples and comparative examples were cut into a width of 5.25 mm, and heat-sealed onto paper carriers with a thickness of 42 mm and containing 5000 electronic components under the following heat-sealing conditions (heat-sealing temperature: 190 °C, heat-sealing pressure: 2 - 3 Mpa, heat-sealing speed: 3300 pcs / min). After being placed in an aging oven at 60 °C and 60 °C / 85% RH for 48 h and then left at room temperature for 24 h, the stripping was carried out by a machine at a speed of 300 mm / min. A cover tape with a sticking rate of less than 0.5% was considered a qualified product.

[0082] Unwinding test:

[0083] The cover tapes corresponding to the above-mentioned examples and comparative examples were cut into a width of 5.25 mm. The cover tapes were wound back and forth, with a length of approximately 8000 m, and placed on a test rack. The cover tapes were allowed to fall freely, and the length of time for the cover tapes to fall freely was recorded to reflect the degree of unwinding. ○ Unwinding time between 3 h and 6 h (qualified); ◎ Unwinding time < 3 h (optimal); ╳ Unwinding time > 6 h (unqualified)

[0084] The test results are shown in Table 1.

[0085] Table 1. Detection results of relevant properties of the cover tapes corresponding to each example

[0086]

Claims

1. A hot-melt composition for a heat-sealing layer of a cover tape, characterized in that, It comprises a mixture of 50 to 85 wt% of a vinyl ester copolymer and a vinyl acid copolymer, 5 to 25 wt% of a tackifying resin, 3 to 15 wt% of an anti-sticking resin, 1 to 8 wt% of anti-sticking particles, and 0.1 to 2 wt% of an antioxidant; the mass ratio of the vinyl ester copolymer to the vinyl acid copolymer is in the range of 60 to 80:20 to 40; the ester monomer content in the vinyl ester copolymer is in the range of 5 to 30%; the acid monomer content in the vinyl acid copolymer is in the range of 4 to 25%.

2. The hot melt composition for a cover tape heat-sealing layer according to claim 1, characterized in that, The vinyl ester copolymer includes one or more of ethylene-vinyl acetate, ethylene-methyl acrylate, ethylene-methyl methacrylate, ethylene-ethyl acrylate, and ethylene-butyl acrylate.

3. A hot-melt composition for a heat-sealing layer of a cover tape, characterized in that, The vinyl acid copolymer includes one or more of ethylene-methyl acrylic acid copolymer, ethylene-acrylic acid copolymer, and ethylene-acrylic acid-maleic anhydride copolymer.

4. A hot melt composition for a heat seal layer of a cover tape, characterized in that, The ring and ball softening point of the tackifying resin is 100°C to 140°C.

5. A hot melt composition for a heat seal layer of a cover tape, characterized in that, The tackifying resin is one or two of hydrogenated rosin resin, C5 resin, C9 resin, hydrogenated C5 resin, hydrogenated C9 resin, and hydrogenated C5 / C9 copolymer resin.

6. The hot-melt composition for the heat-sealing layer of the cover tape according to claim 1, wherein, The anti-sticking resin can be one or two of α-methyl styrene, maleic anhydride grafted high density polyethylene, styrene maleic anhydride copolymer, and phenyl maleimide copolymer.

7. A cover tape, comprising a heat-sealing layer formed of the hot-melt composition according to any one of claims 1-6 above.

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