Adhesive tape as well as preparation method and application thereof

Abstract

The invention relates to an adhesive tape and a preparation method and application thereof.The adhesive tape comprises a base film, an adhesive layer and a release film which are sequentially arranged and bonded, the base film is made of polycarbonate, and the water absorption rate of the base film is smaller than 0.25%; the adhesive layer is prepared from the following components in parts by mass: 100 parts of an acrylic acid adhesive, 0.02 to 0.08 part of an epoxy crosslinking agent and 0.05 to 2 parts of an organic metal compound. The release amount of gas from the base film is reduced by selecting the base film with low water absorption, and the adhesive force of the adhesive tape and an adhered object is improved by adding the organic metal compound into the adhesive layer, so that the problem of appearance foaming of the adhesive tape in a high-temperature forming process is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesive tapes, and in particular to an adhesive tape and a preparation method and application thereof. Background Art

[0002] There is a process for the back cover of the mobile phone that first textures and coats the surface of the back cover and the tape respectively and then bonds the two together. This process can reconstruct the order of the light path, bring visual impact, and easily design a mobile phone back cover with a unique feel and aesthetics. For example, the "A Production Process for a Double-grained and Double-plated Composite Plate Mobile Phone Back Cover" disclosed in the Chinese invention patent application with patent number CN202111074593.2 (publication number CN113844070A) is processed through the following steps, including a composite plate processing process, a diaphragm processing process and a bonding process. The composite plate processing process forms a composite plate carrier with a single grain and single plating, and the diaphragm processing process forms a single diaphragm. The base diaphragm on the single diaphragm is torn off and bonded together with the electroplated layer of the composite plate carrier through OCA glue, and then defoaming treatment is performed after bonding.

[0003] In this process, the OCA adhesive (hereinafter referred to as the tape) will be formed at high temperature after being attached to the back cover. Since the material of the back cover is a PMMA / PC composite board, and the material of the tape base film is generally a polycarbonate film, these two materials will release a small amount of gas during the high temperature process. If the amount of gas released from the tape base film is large, or the adhesion between the tape and the adhered object (i.e. the composite board) is insufficient, more gas will be generated in the high temperature forming process. When the pressure generated by the gas is greater than the adhesion between the tape and the adhered object, bubbles will appear on the surface of the tape, affecting the appearance of the product. Therefore, it is very important to reduce the amount of gas released from the tape base film and increase the adhesion between the tape and the adhered object for the high temperature resistance of the tape. Summary of the invention

[0004] The first technical problem to be solved by the present invention is to provide an adhesive tape with small gas release and strong adhesion under high temperature conditions in view of the above-mentioned prior art.

[0005] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned adhesive tape in view of the above-mentioned prior art.

[0006] The third technical problem to be solved by the present invention is to provide an application of the above-mentioned adhesive tape in view of the above-mentioned prior art.

[0007] The technical solution adopted by the present invention to solve the above-mentioned first technical problem is: an adhesive tape, comprising a base film, an adhesive layer and a release film which are sequentially arranged and bonded, characterized in that: the base film is made of polycarbonate, and its water absorption rate is less than 0.25%;

[0008] The adhesive layer comprises the following components in parts by mass:

[0009] Acrylic adhesive 100 parts

[0010] Epoxy crosslinking agent 0.02-0.08 parts

[0011] 0.05-2 parts of organic metal compound.

[0012] Preferably, the organometallic compound includes an organoaluminum compound, which has good compatibility with the adhesive and a suitable reaction speed.

[0013] Preferably, the organoaluminum compound is one or more of (3-oxobutyrate ethyl ester-O1', O3) di(propanol-2-yl) aluminum, tri(ethyl-3-oxobutoxy-O1', O3)-aluminum, (octadecane-9-enyl acetoacetate-O1', O3) dipropane-2-ol aluminum, diethylacetate ethanol-2,4-pentanedione aluminum, and triacetylacetonate aluminum.

[0014] More preferably, the organoaluminum compound is tris(acetylacetonate)aluminum.

[0015] Preferably, the weight average molecular weight of the acrylic adhesive is 500,000 to 2,000,000, and contains 2% to 10% by mass of carboxyl groups. Such acrylic adhesive has good durability.

[0016] Preferably, the acrylic adhesive is prepared by copolymerization of acrylic monomers, and the acrylic monomers include n-butyl acrylate, isooctyl acrylate, acrylic acid, and methyl acrylate.

[0017] Preferably, the epoxy crosslinking agent is one or more of epoxy acrylate, epoxy methacrylate, and glycerol alkyl epoxy alcohol ester.

[0018] Preferably, the epoxy crosslinking agent is epoxy methacrylate.

[0019] The technical solution adopted by the present invention to solve the second technical problem is: a method for preparing the above-mentioned adhesive tape, characterized in that it comprises the following steps:

[0020] 1. Prepare the adhesive layer. The method for preparing the adhesive layer comprises the following steps:

[0021] Add acrylic adhesive according to the above mass fractions at room temperature, then add epoxy crosslinking agent, stir for 3 minutes to make the materials evenly mixed, then add organic metal compound, stir for 20 minutes to make the materials evenly mixed to obtain a fully mixed adhesive layer.

[0022] 2. The adhesive layer prepared in step 1 is coated on the release film with a coating thickness of 10 to 30 μm, dried at 80° C. for 5 minutes, and then laminated to the base film, rolled up, and aged at 35 to 40° C. for 3 days to obtain the adhesive tape.

[0023] The technical solution adopted by the present invention to solve the third technical problem is: an application of the above-mentioned tape, characterized in that: after tearing off the release film, the adhesive layer of the tape is used to stick on the back cover of a mobile phone, and the back cover of the mobile phone is a composite board.

[0024] Compared with the prior art, the advantages of the present invention are: the present invention reduces the amount of gas released from the base film by selecting a base film with low water absorption, and then improves the adhesion between the tape and the adherend by adding an organic metal compound to the adhesive layer, thereby solving the problem of foaming of the tape during high-temperature molding. The specific principle is as follows:

[0025] In the high-temperature molding process after the tape is attached to the adherend, the back cover and the base film of the tape will release a small amount of gas. When the overflowing gas is large and the gas pressure is greater than the adhesion between the tape and the adherend, blistering will occur. To this end, two methods are combined to achieve high-temperature foaming resistance: 1. The base film selects a PC film with low water absorption to reduce the gas release from the base film of the tape. 2. Organic metal compounds are added to the adhesive layer. This organic metal compound has good affinity with the adhesive layer and will be fully and stably dispersed in the adhesive layer. The part distributed on the surface of the adhesive layer will react with the hydroxyl group on the surface of the adhered object, so that the adhesion between the adhesive layer and the adhered object is improved. When the adhesion between the adhesive layer and the adhered object is greater than the water vapor pressure, the blistering problem will be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a reaction mechanism diagram of the adhesive layer and the base film of the present invention;

[0027] Figure 2 It is a schematic structural diagram of the adhesive tape of the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below with reference to the accompanying drawings.

[0029] like Figure 2 As shown, the adhesive tapes of the embodiments and comparative examples below include a base film 2, an adhesive layer 3 and a release film 4 which are sequentially arranged and bonded. The adhesive tape may also be provided with a PE protective film 1. The PE protective film 1 and the adhesive layer 3 are respectively located on opposite sides of the base film 2. The release film 4 may adopt an existing film layer, such as a single silicon release film.

[0030] After tearing off the release film, the adhesive layer of the tape is used to stick on the back cover of the mobile phone, which is a PMMA / PC composite board.

[0031] The base film is made of polycarbonate, with a water absorption rate of less than 0.25% and a thickness of 75um.

[0032] The adhesive layer includes the following components by mass:

[0033] Acrylic adhesive 100 parts

[0034] Epoxy crosslinking agent 0.02-0.08 parts

[0035] 0.05-2 parts of organic metal compound.

[0036] The method for preparing the adhesive tape comprises the following steps:

[0037] 1. Prepare the adhesive layer. The method for preparing the adhesive layer comprises the following steps:

[0038] Add acrylic adhesive according to the above mass fractions at room temperature, then add epoxy crosslinking agent, stir for 3 minutes to make the materials evenly mixed, then add organic metal compound, stir for 20 minutes to make the materials evenly mixed to obtain a fully mixed adhesive layer.

[0039] 2. The adhesive layer prepared in step 1 is coated on the release film with a coating thickness of 10 to 30 μm, dried at 80° C. for 5 minutes, and then laminated to the base film, rolled up, and aged at 35 to 40° C. for 3 days to obtain the adhesive tape.

[0040] The present invention is further described in detail below in conjunction with embodiments:

[0041] As shown in Table 1, the water absorption rate of the polycarbonate film in Examples 1-7 is lower than 0.25%, and the adhesion to the glass is above 20N / 25mm. There is no problem with the appearance after high temperature heating at 200°C*1min.

[0042] As shown in Table 1 below, in Comparative Examples No. 1 and 2, bubbles appeared on the surface after being heated to high temperature. This is because the polycarbonate film contains more water, which will release more gas at high temperature, resulting in bubbles on the surface.

[0043] In comparison examples No. 3 and 4, adding too little epoxy cross-linking agent will lead to decreased cohesion of the adhesive layer. When gas enters the adhesive layer, the adhesive layer will deform and produce bubbles. Adding too much epoxy cross-linking agent will increase the cohesion of the adhesive layer, reduce the wettability of the adhesive layer, and cause decreased adhesion between the adhesive layer and the adherend, resulting in the generation of bubbles.

[0044] In Comparative Examples No. 5 and 6, when no organometallic aluminum compound is added or the added amount is insufficient, the adhesive strength between the tape and the adherend is insufficient.

[0045] In comparative example No. 7, excessive addition of the organometallic aluminum compound will cause the excess part to participate in the bridging of the glue, and the cohesive force of the glue layer is too high, resulting in reduced adhesion between the glue layer and the adherend, and generating bubbles.

[0046] In summary, the water absorption rate of polycarbonate film and the appropriate amount of organic metal compounds added are two important factors affecting the high temperature resistance of the tape. Selecting a polycarbonate film with a water absorption rate lower than 0.25% and adding appropriate metal organic compounds can solve the problem of poor appearance during the high-temperature molding process of the double-texture double-coating process.

[0047] Table 1:

[0048]

[0049] The organic metal compound used in the above-mentioned embodiments and comparative examples is tri(acetylacetonate)aluminum, and the epoxy crosslinking agent is epoxy methacrylate.

[0050] The acrylic adhesive used in the above-mentioned embodiments and comparative examples was purchased from Ningbo Daxie Development Zone Soken Chemical Co., Ltd.; the epoxy crosslinking agent was purchased from Soken Chemical Co., Ltd.; and the organometallic compound was purchased from Kawaken Fine Chemical Co., Ltd.

[0051] Test Description

[0052] 6.1 Water absorption

[0053] Test standard: ISO 62

[0054] Test conditions:

[0055] 1. Test environment: temperature 23±2℃, humidity 50±5%.

[0056] 2. Test equipment: balance with accuracy of ±0.1mg.

[0057] 3. Test procedure: Place the polycarbonate film sample at 23℃*24H, and measure the mass difference between the sample at the beginning of the test and after absorbing water. Use the mass difference as a percentage of the initial mass, test 5 samples in parallel, and take the average value.

[0058] 4.Test unit: %.

[0059] 6.2 Adhesion

[0060] Test conditions:

[0061] 1. Test environment: temperature 23±2℃, humidity 50±5%.

[0062] 2. Test equipment: Constant speed tensile testing machine; Single-cell (normal glass surface after polishing: wipe clean with alcohol and place in the test environment for 2 hours); 2kg rubber roller.

[0063] 3. Test procedure: The width of the tape is 25mm, and it is attached to the GLASS sheet with a width of 25mm. The temperature is 80℃ and the pressure is 0.6MPa for 30min. After leaving it at room temperature for 1H, it is peeled off at ∠180°. The peeling speed is 300mm / min. Five samples are tested in parallel and the average value is taken.

[0064] 4.Test unit: N / 25mm.

[0065] 6.3 Appearance judgment of high temperature foaming resistance

[0066] Test conditions:

[0067] 1. Test environment: temperature 200℃, time 1min.

[0068] 2. Test equipment: visual and microscopic observation.

[0069] 3. Test procedure: Peel off the release film, stick the tape to the glass plate, place it at 80℃ and 0.6MPa for 30min, place it in an environment with a temperature of 23±2℃ and a humidity of 50±5% for more than 1h, peel off the protective film on the outside of the substrate, place it in a 200℃ oven for 1min, return to room temperature and observe the appearance, and test 5 samples in parallel.

[0070] 4. Test results: ○: no bubbles on the surface; △: few bubbles on the surface; ×: severe bubbles on the surface.

Claims

1. An adhesive tape comprising a base film, an adhesive layer and a release film which are sequentially arranged and bonded, characterized in that: The base film is made of polycarbonate, and its water absorption rate is less than 0.25%; The adhesive layer comprises the following components in parts by mass: Acrylic adhesive 100 parts Epoxy crosslinking agent 0.02-0.08 parts 0.05-2 parts of organic metal compound.

2. The adhesive tape according to claim 1, characterized in that: The organometallic compound includes an organoaluminum compound.

3. The adhesive tape according to claim 2, characterized in that: The organic aluminum compound is one or more of (3-oxobutyric acid ethyl ester-O1', O3) di(propanol-2-root) aluminum, tri(ethyl-3-oxobutoxy-O1', O3)-aluminum, (octadecane-9-enyl acetoacetate-O1', O3) dipropane-2-ol aluminum, diethylacetate ethanol-2,4-pentanedione aluminum, and triacetylacetonate aluminum.

4. The adhesive tape according to claim 3, characterized in that: The organic aluminum compound is tris(acetylacetonate)aluminum.

5. The adhesive tape according to claim 1, characterized in that: The weight average molecular weight of the acrylic adhesive is 500,000 to 2,000,000, and contains 2% to 10% by mass of carboxyl groups.

6. The adhesive tape according to claim 5, characterized in that: The acrylic adhesive is prepared by copolymerization of acrylic monomers, wherein the acrylic monomers include n-butyl acrylate, isooctyl acrylate, acrylic acid and methyl acrylate.

7. The adhesive tape according to claim 1, characterized in that: The epoxy crosslinking agent is one or more of epoxy acrylate, epoxy methacrylate, and glycerol alkyl epoxy alcohol ester.

8. The adhesive tape according to claim 7, characterized in that: The epoxy crosslinking agent is epoxy methacrylate.

9. A method for preparing the adhesive tape according to any one of claims 1 to 8, characterized in that: The steps include:

1. Prepare the adhesive layer. The method for preparing the adhesive layer comprises the following steps: Add acrylic adhesive according to the above mass fractions at room temperature, then add epoxy crosslinking agent, stir to make the materials evenly mixed, then add organic metal compound, stir to make the materials evenly mixed, and obtain a fully mixed adhesive layer.

2. The adhesive layer prepared in step 1 is coated on the release film, and then dried, and the adhesive layer is then laminated to the base film, rolled up, and cured to obtain the adhesive tape.

10. Use of the adhesive tape according to any one of claims 1 to 8, characterized in that: After the release film is torn off, the adhesive layer of the tape is used to stick on the back cover of the mobile phone, and the back cover of the mobile phone is a composite board.

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