Ultralow-viscosity emulsion type pressure-sensitive adhesive for electronic protective film and application of ultralow-viscosity emulsion type pressure-sensitive adhesive

Abstract

The invention relates to the technical field of high polymer materials, in particular to an ultralow-viscosity emulsion type pressure-sensitive adhesive for an electronic protective film and application of the ultralow-viscosity emulsion type pressure-sensitive adhesive. The electronic protective film is prepared from the following main raw material components in parts by weight: 0.5 to 0.8 part of a compound emulsifier, 90 to 110 parts of a mixed monomer, 0.35 to 0.5 part of an initiator, 0.1 to 0.5 part of a buffering agent and 100 to 110 parts of deionized water, the compound emulsifier comprises an anionic emulsifier and a nonionic emulsifier in a content ratio of 1: (0.1-1); the mixed monomer comprises acrylic acid, 2-ethylhexyl acrylate, 2-hydroxypropyl acrylate and styrene; the initiator comprises potassium persulfate and ammonium persulfate in a content ratio of 1: (1-3). The pressure-sensitive adhesive provided by the invention has a unique molecular structure, can ensure no shrinkage cavity after long-time coating, achieves mirror surface coating, and has excellent bubble discharging performance; when being applied to an electronic protective film, the film has no ghosting and adhesive residue phenomenon under the conditions that the temperature is 85 DEG C, the humidity is 85% and the time is 7 days (24 hours); and when the gluing amount is 25g / m < 2 >, the peel strength is stabilized at 1-3g / 25mm, and the peel strength is not increased.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to an ultra-low viscosity emulsion type pressure-sensitive adhesive for an electronic protective film and application thereof. Background Art

[0002] Acrylic pressure-sensitive adhesives used for electronic protective films require higher optical properties and weather resistance, high light transmittance and aging resistance, because electronic devices will generate radiation during use, which will gradually affect the light transmittance and stability of the adhesive layer.

[0003] Rubber pressure-sensitive adhesives can be divided into solvent-based rubber pressure-sensitive adhesives and emulsion-based rubber pressure-sensitive adhesives. At present, the acrylate pressure-sensitive adhesives used for electronic protective films are mainly solvent-based acrylate pressure-sensitive adhesives, which have excellent optical and weather-resistant properties. However, solvent-based acrylate pressure-sensitive adhesives contain organic solvents such as toluene and ethyl acetate, which are very dangerous during production, storage, and transportation. In addition, a large amount of VOC is emitted during the coating process, which not only causes serious pollution to the environment, but also affects the health of operators, and the cost is high. This series of safety, environmental protection, and cost issues have prompted people to urgently develop new pressure-sensitive adhesives.

[0004] As people pay more attention to environmental protection, safety, and energy saving, and the application of pressure-sensitive adhesives continues to expand, pressure-sensitive adhesives are developing in the direction of low pollution, high performance, and functionalization. Acrylic emulsion pressure-sensitive adhesives for electronic protective films are environmentally friendly and safe, and have a clear trend of replacing oil-based pressure-sensitive adhesives. Summary of the invention

[0005] The purpose of the present invention is: based on the above technical problems, to provide an ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective films and its application in electronic protective films.

[0006] The technical solutions adopted are as follows:

[0007] The first aspect of the present invention provides an ultra-low viscosity emulsion pressure-sensitive adhesive for an electronic protective film, which comprises the following main raw material components in parts by weight:

[0008] 0.5-0.8 parts of composite emulsifier, 90-110 parts of mixed monomers, 0.35-0.5 parts of initiator, 0.1-0.5 parts of buffer, 100-110 parts of deionized water;

[0009] The composite emulsifier is an anionic emulsifier and a nonionic emulsifier in a content ratio of 1:0.1-1;

[0010] The mixed monomers include acrylic acid, isooctyl acrylate, 2-hydroxypropyl acrylate, and styrene;

[0011] The initiator is potassium persulfate and ammonium persulfate in a content ratio of 1:1-3.

[0012] Preferably, the composite emulsifier is an anionic emulsifier and a nonionic emulsifier in a content ratio of 1:0.7-1.

[0013] More preferably, the anionic emulsifier is at least one of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate, nonylphenol polyoxyethylene (4) ether ammonium sulfate, and sodium vinyl sulfonate.

[0014] Preferably, the nonionic emulsifier is allyloxy polyoxyethylene (10) ether or nonylphenol polyoxyethylene (10) ether.

[0015] Preferably, in the mixed monomer, by weight, the content of acrylic acid is 2 to 4 parts, the content of isooctyl acrylate is 80 to 90 parts, the content of 2-hydroxypropyl acrylate is 3 to 6 parts, and the content of styrene is 10 to 15 parts.

[0016] Preferably, the buffer is at least one of sodium bicarbonate, sodium hydrogen phosphate, ammonium bicarbonate and sodium acetate.

[0017] According to a particularly preferred embodiment, the method for preparing the ultra-low viscosity emulsion pressure-sensitive adhesive for the electronic protective film comprises the following steps:

[0018] (1) weighing 0.4 to 0.6 parts of a composite emulsifier, adding 30 to 40 parts of deionized water, and performing a first stirring to obtain an emulsifier aqueous solution; slowly adding a mixed monomer to the emulsifier aqueous solution, and performing a second stirring to obtain a pre-emulsified solution;

[0019] (2) Weigh 0.19-0.25 parts of initiator, add 10-15 parts of deionized water, stir to dissolve, add 0.1-0.15 parts of composite emulsifier, 0.1-0.5 parts of buffer, 50-60 parts of deionized water, mix well, heat, and when the temperature rises to 80-85° C., drop 50% of the pre-emulsion obtained in step (1), after 30-35 minutes, add 0.19-0.2 parts of initiator, drop the remaining pre-emulsion obtained in step (1), carry out polymerization reaction, cool to 40° C., adjust the pH value to 7-8, filter and discharge the material, and obtain an ultra-low viscosity emulsion type pressure-sensitive adhesive for electronic protective film.

[0020] More preferably, in step (1), the first stirring conditions meet the following requirements: room temperature, a rotation speed of 700 to 800 r / min, and a time of 20 to 25 min.

[0021] Preferably, in step (1), the second stirring condition satisfies: a rotation speed of 800 to 900 r / min and a time of 30 to 45 min.

[0022] Further preferably, in step (2), the initiator is potassium persulfate and ammonium persulfate in a dosage ratio of 1:1 to 2.

[0023] Preferably, in step (2), the polymerization reaction conditions meet the following requirements: temperature is 80-85° C., and time is 1-2 h.

[0024] The second aspect of the present invention provides the use of the ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective film described in the first aspect of the present invention in the electronic protective film.

[0025] The present invention has the following beneficial effects:

[0026] (1) The ultra-low viscosity emulsion type pressure-sensitive adhesive for electronic protective film of the present invention is a composite emulsifier with a specific content of anionic emulsifier and nonionic emulsifier, a mixed monomer with a specific content of acrylic acid, isooctyl acrylate, 2-hydroxypropyl acrylate, and styrene, and a specific content of potassium persulfate and ammonium persulfate as initiators. In combination with the other technical features of the present invention, the ultra-low viscosity emulsion type pressure-sensitive adhesive for electronic protective film has a unique molecular structure and stability, can ensure long-term coating without shrinkage holes, can achieve mirror coating, and has excellent bubble removal performance; when used for electronic protective film, at a temperature of 85°C and a humidity of 85%, there is no ghosting and no residual glue phenomenon, and when the glue coating amount is 25g / m 2 The peel strength is stable at 1-3g / 25mm, and there is no peel strength increase.

[0027] (2) The ultra-low viscosity emulsion type pressure-sensitive adhesive for electronic protective film of the present invention adds at least one of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate, nonylphenol polyoxyethylene (4) ether ammonium sulfate, and sodium vinyl sulfonate as an anionic emulsifier, and allyloxy polyoxyethylene (10) ether or nonylphenol polyoxyethylene (10) ether is used as a nonionic emulsifier. In emulsion polymerization, emulsifier is the most important factor affecting the stability of emulsion polymerization reaction. The polymerization stability of the emulsion system of anionic / nonionic composite emulsifier is higher than that of anionic emulsifier alone or nonionic emulsifier alone, because anionic emulsifier and nonionic emulsifier stabilize the emulsion with double electric layer structure and hydration layer respectively; the combination of anionic and nonionic emulsifier not only increases the distance between emulsifier molecules on the surface of latex particles, but also greatly reduces the electrostatic tension on the surface of latex particles due to the electrostatic shielding effect of nonionic emulsification, increases the adsorption fastness of emulsifier, and increases the stability of polymer emulsion. The inventors of the present invention have discovered that in an ultra-low viscosity emulsion-type pressure-sensitive adhesive for electronic protective film, when the content ratio of the anionic emulsifier to the nonionic emulsifier is 1:0.1-1, calculated by weight, it is possible to reduce the electrostatic tension on the surface of the latex particles, increase the adsorption fastness of the emulsifier, and increase the stability of the polymer emulsion. Combined with the other technical features of the present invention, the stability of the obtained ultra-low viscosity emulsion-type pressure-sensitive adhesive for electronic protective film is further improved.

[0028] (3) A buffer is added to the ultra-low viscosity emulsion type pressure-sensitive adhesive for electronic protective film of the present invention. The inventors of the present invention have found that, calculated by mass percentage, when the addition amount of the buffer is 1.5-2wt%, the "auto-acceleration" phenomenon in the polymerization process can be alleviated. In combination with the other technical features of the present invention, the stability of the ultra-low viscosity emulsion type pressure-sensitive adhesive for electronic protective film obtained is further improved; the "auto-acceleration" phenomenon is that the initiator produces HSO during the decomposition process. 4- , which catalyzes the thermal decomposition of persulfate.

[0029] (4) The ultra-low viscosity emulsion type pressure-sensitive adhesive for electronic protective film of the present invention adds specific amounts of acrylic acid, isooctyl acrylate, 2-hydroxypropyl acrylate, and styrene as mixed monomers. The inventors of the present invention found that, in parts by weight, when the content of the acrylic acid is 2 to 4 parts, the content of the isooctyl acrylate is 80 to 90 parts, the content of the 2-hydroxypropyl acrylate is 3 to 6 parts, and the content of the styrene is 10 to 15 parts, combined with the other technical features of the present invention, the obtained ultra-low viscosity emulsion type pressure-sensitive adhesive for electronic protective film has a low viscosity while having excellent stability. DETAILED DESCRIPTION

[0030] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0031] In the present invention, "50% of the pre-emulsion obtained in step (1)" refers to 50% of the total weight of the pre-emulsion.

[0032] The ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective film and its application are described below in conjunction with specific embodiments.

[0033] In the following examples, unless otherwise specified, all raw materials used are commercially available.

[0034] In the following examples, normal temperature is 25°C±2°C.

[0035] Example 1

[0036] This example is used to provide a method for preparing an ultra-low viscosity emulsion type pressure-sensitive adhesive for an electronic protective film, the method comprising the following steps:

[0037] (1) Weigh 0.15 g of sodium vinyl sulfonate, 0.1 g of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate, 0.2 g of allyloxy polyoxyethylene (10) ether, and 36 g of deionized water, and stir at room temperature and a speed of 800 r / min for 20 min to obtain an emulsifier aqueous solution;

[0038] Slowly add mixed monomers to the emulsifier aqueous solution and stir at a speed of 850 r / min for 45 minutes to obtain a pre-emulsion; the mixed monomers include: 2g acrylic acid, 80g isooctyl acrylate, 6g 2-hydroxypropyl acrylate, and 12g styrene.

[0039] (2) Weigh 0.19 g of initiator, add it to 10 g of deionized water, stir to dissolve, add 0.05 g of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate, 0.1 g of allyloxy polyoxyethylene (10) ether, then add 0.5 g of sodium bicarbonate and 60 g of deionized water, mix well, heat, and when the temperature rises to 80° C., add 50% of the pre-emulsion obtained in step (1) dropwise, after 30 minutes, add 0.19 g of initiator, and add the remaining pre-emulsion obtained in step (1) dropwise, after the addition is complete, keep the reaction at 80° C. for 1.5 hours, cool to 40° C., adjust the pH value to 7.8, filter the material, and obtain an ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective film; the initiator is potassium persulfate and ammonium persulfate in a mass ratio of 1:1.

[0040] Example 2

[0041] This example is used to provide a method for preparing an ultra-low viscosity emulsion type pressure-sensitive adhesive for an electronic protective film, the method comprising the following steps:

[0042] (1) Weigh 0.25 g of nonylphenol polyoxyethylene (4) ether ammonium sulfate, 0.1 g of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate, 0.25 g of allyloxy polyoxyethylene (10) ether, and 40 g of deionized water, and stir at room temperature and a speed of 800 r / min for 25 min to obtain an emulsifier aqueous solution;

[0043] Slowly add mixed monomers to the emulsifier aqueous solution and stir at a speed of 800 r / min for 45 minutes to obtain a pre-emulsion; the mixed monomers include: 2g acrylic acid, 90g isooctyl acrylate, 3g 2-hydroxypropyl acrylate, and 15g styrene.

[0044] (2) Weigh 0.2 g of initiator, add it to 12 g of deionized water, stir to dissolve, add 0.05 g of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate, 0.05 g of allyloxy polyoxyethylene (10) ether, then add 0.3 g of sodium bicarbonate and 60 g of deionized water, mix well, heat, and when the temperature rises to 85° C., add 50% of the pre-emulsion obtained in step (1) dropwise. After 32 minutes, add 0.2 g of initiator, and add the remaining pre-emulsion obtained in step (1) dropwise. After the addition is complete, keep the reaction at 85° C. for 1.5 hours, cool to 40° C., adjust the pH value to 7.5, filter the material, and obtain an ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective film; the initiator is potassium persulfate and ammonium persulfate in a mass ratio of 1:1.

[0045] Example 3

[0046] This example is used to provide a method for preparing an ultra-low viscosity emulsion type pressure-sensitive adhesive for an electronic protective film, the method comprising the following steps:

[0047] (1) Weigh 0.2 g of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate, 0.2 g of nonylphenol polyoxyethylene (10) ether, and 30 g of deionized water, and stir at room temperature and a speed of 750 r / min for 25 min to obtain an emulsifier aqueous solution;

[0048] Slowly add mixed monomers to the emulsifier aqueous solution and stir at a speed of 900 r / min for 40 minutes to obtain a pre-emulsion; the mixed monomers include: 4g acrylic acid, 80g isooctyl acrylate, 6g 2-hydroxypropyl acrylate, and 10g styrene.

[0049] (2) Weigh 0.25 g of initiator, add it to 15 g of deionized water, stir to dissolve, add 0.05 g of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate, 0.05 g of nonylphenol polyoxyethylene (10) ether, then add 0.1 g of sodium bicarbonate and 60 g of deionized water, mix well, heat, and when the temperature rises to 80° C., add 50% of the pre-emulsion obtained in step (1) dropwise. After 35 minutes, add 0.2 g of initiator, and add the remaining pre-emulsion obtained in step (1) dropwise. After the addition is complete, keep the reaction at 80° C. for 1.5 hours, cool to 40° C., adjust the pH value to 8, filter the material, and obtain an ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective film; the initiator is potassium persulfate and ammonium persulfate in a mass ratio of 1:2.

[0050] Comparative Example 1

[0051] The method of Example 1 is followed, except that the composite emulsifier is an anionic emulsifier and a nonionic emulsifier in a dosage ratio of 1:2. Specifically, in step (1), the dosage of sodium vinyl sulfonate is 0.1 g, the dosage of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate is 0.1 g, and the dosage of allyloxy polyoxyethylene (10) ether is 0.3 g; in step (2), the dosage of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate is 0.1 g, and the dosage of allyloxy polyoxyethylene (10) ether is 0.3 g. The remaining steps and parameters are the same as those of Example 1.

[0052] Comparative Example 2

[0053] The method of Example 1 is followed, except that the initiator is potassium persulfate, and the remaining steps and parameters are the same as those of Example 1.

[0054] Comparative Example 3

[0055] The method of Example 1 was followed, except that no buffer was added, and the remaining steps and parameters were the same as in Example 1.

[0056] Test Case

[0057] The electronic protective films prepared in the above examples and comparative examples were coated on the surface of the PE substrate with an ultra-low viscosity emulsion type pressure-sensitive adhesive, with a coating amount of 25 g / m 2 , and the obtained pressure-sensitive tape was tested, and the results are shown in Table 1.

[0058] Among them, the peel strength of pressure-sensitive adhesive tape is carried out according to GB-2792-81 standard;

[0059] The aging test was conducted at a temperature of 85°C and a humidity of 85% for 7 days (24 hours);

[0060] The viscosity test was carried out at 25°C using a NDJ-type rotational viscometer in accordance with GB / T 2794-1995 standard.

[0061] Table 1

[0062]

[0063] It can be seen from the above results that the ultra-low viscosity emulsion pressure-sensitive adhesive tape for electronic protective film obtained by the present invention has significantly better stability, peel strength, and lower viscosity.

[0064] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. An ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective film, characterized in that: The main raw material components are as follows: 0.5-0.8 parts of composite emulsifier, 90-110 parts of mixed monomers, 0.35-0.5 parts of initiator, 0.1-0.5 parts of buffer, 100-110 parts of deionized water; The composite emulsifier is an anionic emulsifier and a nonionic emulsifier in a content ratio of 1:0.1-1; The mixed monomers include acrylic acid, isooctyl acrylate, 2-hydroxypropyl acrylate, and styrene; The initiator is potassium persulfate and ammonium persulfate in a content ratio of 1:1-3.

2. The ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective film according to claim 1, wherein: The composite emulsifier is an anionic emulsifier and a nonionic emulsifier in a content ratio of 1:0.7-1; And / or, the anionic emulsifier is at least one of allyloxy nonylphenol polyoxyethylene (10) ether ammonium sulfate, nonylphenol polyoxyethylene (4) ether ammonium sulfate, and sodium vinyl sulfonate; And / or, the nonionic emulsifier is allyloxy polyoxyethylene (10) ether or nonylphenol polyoxyethylene (10) ether.

3. The ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective film according to claim 1 or 2, wherein: In the mixed monomer, by weight, the content of acrylic acid is 2 to 4 parts, the content of isooctyl acrylate is 80 to 90 parts, the content of 2-hydroxypropyl acrylate is 3 to 6 parts, and the content of styrene is 10 to 15 parts.

4. The ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective film according to claim 1 or 2, wherein: The buffer is at least one of sodium bicarbonate, sodium hydrogen phosphate, ammonium bicarbonate and sodium acetate.

5. The ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective film according to claim 1 or 2, wherein: The method for preparing the ultra-low viscosity emulsion type pressure-sensitive adhesive for the electronic protective film comprises the following steps: (1) weighing 0.4 to 0.6 parts of a composite emulsifier, adding 30 to 40 parts of deionized water, and performing a first stirring to obtain an emulsifier aqueous solution; slowly adding a mixed monomer to the emulsifier aqueous solution, and performing a second stirring to obtain a pre-emulsified solution; (2) Weigh 0.19-0.25 parts of initiator, add 10-15 parts of deionized water, stir to dissolve, add 0.1-0.15 parts of composite emulsifier, 0.1-0.5 parts of buffer, 50-60 parts of deionized water, mix well, heat, and when the temperature rises to 80-85° C., drop 50% of the pre-emulsion obtained in step (1), after 30-35 minutes, add 0.19-0.2 parts of initiator, drop the remaining pre-emulsion obtained in step (1), carry out polymerization reaction, cool to 40° C., adjust the pH value to 7-8, filter and discharge the material, and obtain an ultra-low viscosity emulsion type pressure-sensitive adhesive for electronic protective film.

6. The ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective film according to claim 5, wherein: In step (1), the first stirring conditions meet the following requirements: room temperature, a rotation speed of 700 to 800 r / min, and a time of 20 to 25 min.

7. The ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective film according to claim 5, wherein: In step (1), the second stirring condition meets the following requirements: the rotation speed is 800-900 r / min and the time is 30-45 min.

8. The ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective film according to claim 5, wherein: In step (2), the initiator is potassium persulfate and ammonium persulfate in a dosage ratio of 1:1-2.

9. The ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective film according to claim 5, wherein: In step (2), the polymerization reaction conditions are as follows: temperature is 80-85° C., and time is 1-2 h.

10. Use of the ultra-low viscosity emulsion pressure-sensitive adhesive for electronic protective films according to any one of claims 1 to 9 in electronic protective films.

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