Water-based acrylic emulsion adhesive, pressure-sensitive adhesive and preparation method thereof

Abstract

The invention discloses an aqueous acrylic emulsion rubber, a pressure-sensitive adhesive and a preparation method thereof. The aqueous acrylic emulsion rubber comprises the following components in parts by weight: 40.0-50.0 parts of deionized water, 0.5-2.2 parts of an emulsifier, 40.0-60.0 parts of butyl acrylate, 5.0-10.0 parts of methyl acrylate, 2.0-5.0 parts of methyl methacrylate, 1.0-2.0 parts of hydroxyethyl acrylate, 0.5-1.5 parts of beta-carboxyethyl acrylate, 0.01-0.05 parts of mercaptan, 0.1-1.0 parts of an initiator, 0.01-0.05 parts of a redox agent, 0.01-0.05 parts of sodium bicarbonate, 3.0-5.0 parts of ammonia water and 4.0-7.0 parts of a low surface tension solvent; the emulsifier is SR-10 and / or ER-20; and the low surface tension solvent is ethanol or isopropanol. It is used to prepare water-based pressure-sensitive adhesives, which can greatly reduce the problems of allergies and redness caused by the migration of small molecule additives.

Description

Technical Field

[0001] The invention relates to the field of chemical industry, in particular to a water-based acrylic emulsion adhesive, a pressure-sensitive adhesive and a preparation method thereof. Background Art

[0002] At present, medical pressure-sensitive adhesives are mainly oil-based pressure-sensitive adhesives. With the requirements of environmental protection and health, the demand for water-based pressure-sensitive adhesives is increasing. Water-based pressure-sensitive adhesives are generally composed of latex stock solution and thickening emulsion. The emulsifiers and additives in the existing latex stock solution are small molecules and do not participate in the reaction. After the film is coated in the later stage, they remain in the tape and are easy to migrate after contact with the skin, which makes the skin prone to allergies and redness. Summary of the invention

[0003] In order to overcome the deficiencies of the prior art, the present invention aims to provide a water-based acrylic emulsion base rubber, which is used to prepare a water-based pressure-sensitive adhesive and can greatly reduce the problems of allergies and redness caused by the migration of small molecule additives.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0005] A water-based acrylic emulsion rubber is prepared from the following components in parts by weight: 40.0-50.0 parts of deionized water, 0.5-2.2 parts of an emulsifier, 40.0-60.0 parts of butyl acrylate, 5.0-10.0 parts of methyl acrylate, 2.0-5.0 parts of methyl methacrylate, 1.0-2.0 parts of hydroxyethyl acrylate, 0.5-1.5 parts of beta-carboxyethyl acrylate, 0.01-0.05 parts of mercaptan, 0.1-1.0 parts of an initiator, 0.01-0.05 parts of a redox agent, 0.01-0.05 parts of sodium bicarbonate, 3.0-5.0 parts of ammonia water and 4.0-7.0 parts of a low surface tension solvent; the emulsifier is SR-10 and / or ER-20; and the low surface tension solvent is ethanol or isopropanol.

[0006] Preferably, the initiator is ammonium persulfate or sodium persulfate.

[0007] Preferably, the redox agent is any one of tert-butyl peroxide, sodium formaldehyde sulfoxylate and sodium bisulfite.

[0008] The present invention also includes a method for preparing the aqueous acrylic emulsion rubber described in any one of the above items, comprising the steps of:

[0009] S101. Add part of the deionized water to the container A, add the emulsifier under stirring conditions, disperse at high speed for 20-40min, then add the monomers butyl acrylate, methyl acrylate, methyl methacrylate, hydroxyethyl acrylate, β-carboxyethyl acrylate and mercaptan, and continue to disperse at high speed for 20-40min to form a pre-emulsion;

[0010] S102. Take 2%-5% of the weight of the pre-emulsion prepared in step S101 as seeds, add them into container B together with the remaining deionized water and sodium bicarbonate, raise the temperature to 80-83°C, and then add part of the initiator into container B; at the same time, add the remaining initiator to the pre-emulsion in container A;

[0011] S103. When the initiation is successful, the container B is judged to have obvious blue light. At this time, the temperature in the container B is kept constant, and the pre-emulsion mixed with the initiator in the container A is added dropwise to the container, and the addition time is controlled to be 3-4 hours. After the addition is completed, the temperature is kept for 1 hour. After the insulation is completed, the temperature is lowered to 70-75°C, and a redox agent is added to remove the residual monomers and the temperature is kept for 30 minutes.

[0012] S104. After the heat preservation is completed, the temperature is lowered to below 50°C, ammonia water is added to adjust the pH value to 7-8, and a low surface tension solvent is added. After stirring for 5.0-10.0 minutes, the latex rubber is obtained by filtering with a nylon filter.

[0013] Furthermore, in step 101, the rotation speed during high-speed dispersion is 300 rpm.

[0014] Furthermore, the mesh number of the nylon filter is 300 meshes.

[0015] The present invention also includes a water-based acrylic pressure-sensitive adhesive, which is prepared by mixing 100.0 parts of the water-based acrylic emulsion rubber described in any one of the above items and 20 parts of a tackifying emulsion, wherein the tackifying emulsion is DERMULSENETR602 of DRT.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. In the present invention, the preparation of the emulsion raw gum adopts a reactive emulsifier, which can participate in the reaction and avoid the precipitation of small molecules; the wettability of the emulsion is improved by adding a solvent with low surface tension in the later stage, without adding a small molecule wetting agent; the viscosity is controlled by adjusting the seed ratio and the ammonia ratio, without adding a small molecule thickener; thereby reducing the problems of allergies and redness caused by the migration of small molecule additives;

[0018] 2. Through reasonable monomer ratio and the introduction of special acrylic monomer of β-carboxyethyl acrylate, the peeling force and bonding force of pressure-sensitive adhesive are greatly improved;

[0019] 3. In the preparation process of the pressure-sensitive adhesive, an excellent tackifying emulsion is selected. The general tackifying emulsion is yellow-brown in color, which makes the appearance of the tape yellowish. Although the peeling force can be improved after adding it, the initial adhesion is significantly reduced. The tackifying emulsion selected by the present invention is light in color, the appearance of the prepared pressure-sensitive adhesive has no obvious hue, and has no obvious effect on the initial adhesion. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with specific implementation modes.

[0021] The invention comprises an aqueous acrylic emulsion rubber, which is prepared from the following components in parts by weight: 40.0-50.0 parts of deionized water, 0.5-2.2 parts of an emulsifier, 40.0-60.0 parts of butyl acrylate, 5.0-10.0 parts of methyl acrylate, 2.0-5.0 parts of methyl methacrylate, 1.0-2.0 parts of hydroxyethyl acrylate, 0.5-1.5 parts of beta-carboxyethyl acrylate, 0.01-0.05 parts of mercaptan, 0.1-1.0 parts of an initiator, 0.01-0.05 parts of an oxidation-reduction agent, 0.01-0.05 parts of sodium bicarbonate, 3.0-5.0 parts of ammonia water and 4.0-7.0 parts of a low surface tension solvent; the emulsifier is SR-10 and / or ER-20; and the low surface tension solvent is ethanol or isopropanol.

[0022] Preferably, the initiator is ammonium persulfate or sodium persulfate. The redox agent is any one of tert-butyl peroxide, sodium formaldehyde sulfoxylate and sodium bisulfite.

[0023] The present invention also includes a method for preparing the aqueous acrylic emulsion rubber described in any one of the above items, comprising the steps of:

[0024] S101. Add part of the deionized water to the container A, add the emulsifier under stirring conditions, disperse at high speed for 20-40min, then add the monomers butyl acrylate, methyl acrylate, methyl methacrylate, hydroxyethyl acrylate, β-carboxyethyl acrylate and mercaptan, and continue to disperse at high speed for 20-40min to form a pre-emulsion;

[0025] S102. Take 2%-5% of the weight of the pre-emulsion prepared in step S101 as seeds, add them into container B together with the remaining deionized water and sodium bicarbonate, raise the temperature to 80-83°C, and then add part of the initiator into container B; at the same time, add the remaining initiator to the pre-emulsion in container A;

[0026] S103. When the initiation is successful, the container B is judged to have obvious blue light. At this time, the temperature in the container B is kept constant, and the pre-emulsion mixed with the initiator in the container A is added dropwise to the container, and the addition time is controlled to be 3-4 hours. After the addition is completed, the temperature is kept for 1 hour. After the insulation is completed, the temperature is lowered to 70-75°C, and a redox agent is added to remove the residual monomers and the temperature is kept for 30 minutes.

[0027] S104. After the heat preservation is completed, the temperature is lowered to below 50°C, ammonia water is added to adjust the pH value to 7-8, and a low surface tension solvent is added. After stirring for 5.0-10.0 minutes, the latex rubber is obtained by filtering with a nylon filter.

[0028] Furthermore, in step 101, the rotation speed during high-speed dispersion is 300 rpm. The mesh size of the nylon filter is 300 meshes.

[0029] The present invention also includes a water-based acrylic pressure-sensitive adhesive, which is prepared by mixing 100.0 parts of the water-based acrylic emulsion rubber described in any one of the above items and 20 parts of a tackifying emulsion, wherein the tackifying emulsion is a phenol-modified terpene resin prepared by emulsion polymerization. The tackifying emulsion is DRT's DERMULSENE TR602.

[0030] Example 1

[0031] Add 20.0 parts of deionized water to four-necked flask A, start stirring, then add 0.5 parts of emulsifier SR-10, disperse at 300rpm for 30 minutes, then add 45.0 parts of butyl acrylate, 6.0 parts of methyl acrylate, 2.0 parts of methyl methacrylate, 1.0 parts of hydroxyethyl acrylate, 1.5 parts of β-carboxyethyl acrylate and 0.03 parts of mercaptan, and continue to disperse at high speed for 30 minutes to form a viscous pre-emulsion. Add 20.0 parts of deionized water and 0.02 parts of sodium bicarbonate to four-necked flask B, take 3% of the above pre-emulsion as seeds and add it to the flask, heat to 80°C, add 0.2 parts of initiator ammonium persulfate, and add 0.3 parts of initiator ammonium persulfate to the pre-emulsion. There is obvious blue light in the bottle. 3 minutes after the successful initiation, start to drip the pre-emulsion, and the dripping time is controlled within 4 hours. After the dripping is completed, keep warm for 1 hour. After the insulation is completed, cool to 72°C, add 0.02 parts of redox agent tert-butyl peroxide, and keep warm for 30 minutes. After the insulation is completed, cool to below 50°C, add 3.0 parts of ammonia water to adjust the pH value to 7, and add 4.0 parts of low surface tension solvent ethanol. After stirring for 10 minutes, filter with a 300-mesh nylon filter to obtain the emulsion original rubber S-1.

[0032] Example 2

[0033] Add 20.0 parts of deionized water to four-necked flask A, start stirring, then add 0.5 parts of emulsifiers SR-10 and ER-20, disperse at 300rpm for 30 minutes, then add 40.0 parts of butyl acrylate, 5.0 parts of methyl acrylate, 2.0 parts of methyl methacrylate, 1.0 parts of hydroxyethyl acrylate, 1.5 parts of β-carboxyethyl acrylate and 0.04 parts of mercaptan, and continue to disperse at high speed for 30 minutes to form a viscous pre-emulsion. Add 30.0 parts of deionized water and 0.05 parts of sodium bicarbonate to four-necked flask B, take 3% of the above pre-emulsion as seeds and add it to the flask, heat to 80℃, add 0.3 parts of initiator ammonium persulfate, and add 0.2 parts of initiator ammonium persulfate to the pre-emulsion. There is obvious blue light in the bottle. 3 minutes after the successful initiation, start to drip the pre-emulsion, and the dripping time is controlled at 3.5 hours. After the dripping is completed, keep warm for 1 hour. After the insulation is completed, cool to 74°C, add 0.02 parts of redox agent formaldehyde sodium sulfoxylate, and keep warm for 30 minutes. After the insulation is completed, cool to below 50°C, add 3.0 parts of ammonia water to adjust the pH value to 7 and add 5.0 parts of low surface tension solvent isopropanol. After stirring for 10 minutes, filter with a 300-mesh nylon filter to obtain the emulsion original rubber S-2.

[0034] Example 3

[0035] Add 20.0 parts of deionized water to four-necked flask A, start stirring, then add 1.0 parts of emulsifier SR-10 and 0.8 parts of ER-20, disperse at 300rpm for 30 minutes, then add 50.0 parts of butyl acrylate, 6.0 parts of methyl acrylate, 4.0 parts of methyl methacrylate, 1.5 parts of hydroxyethyl acrylate, 1.0 parts of β-carboxyethyl acrylate and 0.04 parts of mercaptan, and continue to disperse at high speed for 30 minutes to form a viscous pre-emulsion. Add 30.0 parts of deionized water and 0.02 parts of sodium bicarbonate to four-necked flask B, take 2% of the above pre-emulsion as seeds and add it to the flask, heat to 80℃, add part of 0.4 parts of initiator ammonium persulfate, and add 0.3 parts of initiator ammonium persulfate to the pre-emulsion. There is obvious blue light in the bottle. 3 minutes after the successful initiation, start to drip the pre-emulsion, and the dripping time is controlled within 3 hours. After the dripping is completed, keep warm for 1 hour. After the insulation is completed, cool to 74°C, add 0.03 parts of redox agent tert-butyl peroxide, and keep warm for 30 minutes. After the insulation is completed, cool to below 50°C, add 4.0 parts of ammonia water to adjust the pH value to 7, and add 4.0 parts of low surface tension solvent ethanol. After stirring for 10 minutes, filter with a 300-mesh nylon filter to obtain the emulsion original rubber S-3.

[0036] Example 4

[0037] Add 20.0 parts of deionized water to four-necked flask A, start stirring, then add 1.1 parts of emulsifiers SR-10 and ER-20, disperse at 300rpm for 30 minutes, then add monomers 45.0 parts of butyl acrylate, 8.0 parts of methyl acrylate, 4.0 parts of methyl methacrylate, 1.0 parts of hydroxyethyl acrylate, 0.5 parts of β-carboxyethyl acrylate and 0.02 parts of mercaptan, continue to disperse at high speed for 30 minutes to form a viscous pre-emulsion. Add 30.0 parts of deionized water and 0.04 parts of sodium bicarbonate to four-necked flask B, take 4% of the above pre-emulsion as seeds and add it to the flask, heat to 80°C, add 0.5 parts of initiator ammonium persulfate, and add 0.4 parts of initiator sodium persulfate to the pre-emulsion. There is obvious blue light in the bottle. 3 minutes after the successful initiation, start to drip the pre-emulsion, and the dripping time is controlled at 3.5 hours. After the dripping is completed, keep warm for 1 hour. After the insulation is completed, cool to 74°C, add 0.04 parts of redox agent sodium bisulfite, and keep warm for 30 minutes. After the insulation is completed, cool to below 50°C, add 4.0 parts of ammonia water to adjust the pH value to 7 and add 6.0 parts of low surface tension solvent ethanol. After stirring for 10 minutes, filter with a 300-mesh nylon filter to obtain the emulsion original rubber S-4.

[0038] Example 5

[0039] Add 20.0 parts of deionized water to four-necked flask A, start stirring, then add 2.0 parts of emulsifier ER-20, disperse at 300rpm for 30 minutes, then add 60.0 parts of butyl acrylate, 10.0 parts of methyl acrylate, 4.0 parts of methyl methacrylate, 1.0 parts of hydroxyethyl acrylate, 0.5 parts of β-carboxyethyl acrylate and 0.05 parts of mercaptan, and continue to disperse at high speed for 30 minutes to form a viscous pre-emulsion. Add 30.0 parts of deionized water and 0.04 parts of sodium bicarbonate to four-necked flask B, take 4% of the above pre-emulsion as seeds and add it to the flask, raise to 83°C, add 0.4 parts of initiator sodium persulfate, and add 0.5 parts of initiator sodium persulfate to the pre-emulsion. There is obvious blue light in the bottle. 3 minutes after the successful initiation, start to drip the pre-emulsion, and the dripping time is controlled at 3.5 hours. After the dripping is completed, keep warm for 1 hour. After the insulation is completed, cool it to 72°C, add 0.04 parts of redox agent sodium bisulfite, and keep warm for 30 minutes. After the insulation is completed, cool it to below 50°C, add 5.0 parts of ammonia water to adjust the pH value to 8, and add 7.0 parts of low surface tension solvent ethanol. After stirring for 10 minutes, filter it with a 300-mesh nylon filter to obtain the emulsion original rubber S-5.

[0040] Comparative Example 1 Conventional preparation of latex rubber

[0041] Add 20.0 parts of deionized water to four-necked flask A, start stirring, then add 0.5 parts of alkylphenol / fatty alcohol polyether emulsifier OP-10 and 2A1, disperse at high speed for 30 minutes, then add monomers 40.0 parts of butyl acrylate, 5.0 parts of methyl acrylate, 2.0 parts of methyl methacrylate, 1.0 parts of hydroxyethyl acrylate, 1.5 parts of β-carboxyethyl acrylate and 0.04 parts of mercaptan, 0.2 parts of initiator ammonium persulfate, continue to disperse at high speed for 30 minutes to form a viscous pre-emulsion. Add 30.0 parts of deionized water and 0.05 parts of sodium bicarbonate to four-necked flask B, heat to 80°C, and add 0.3 parts of initiator ammonium persulfate. There is obvious blue light in the bottle. 3 minutes after the successful initiation, start to drip the pre-emulsion, and the dripping time is controlled at 3.5 hours. After the dripping is completed, keep warm for 1 hour. After the insulation is completed, cool it to 74°C, add 0.02 parts of redox agent, and keep warm for 30 minutes. After the insulation is completed, cool it to below 50°C, add 3.0 parts of ammonia water and 5.0 parts of wetting agent succinic acid monoester sulfonate. After stirring for 10 minutes, filter it with a 300-mesh nylon filter to obtain the emulsion original rubber D-1.

[0042] Comparative Example 2

[0043] The emulsion rubbers S-1 to S-5 prepared in Examples 1-5 and the emulsion rubber D-1 prepared in Comparative Example 1 were divided into two groups, one group was added with 20% by weight of the tackifying emulsion of the present invention (phenol-modified terpene resin prepared by emulsion polymerization, in this case, DERMULSENE TR602 of DRT) to prepare 6 kinds of pressure-sensitive adhesives, and the other group was added with 20% by weight of a commercially available tackifying emulsion (tackifying resin prepared by post-emulsification of pentaerythritol ester and rosin, in this case, BJ130 of German Blue Giant Chemical) to prepare 6 kinds of pressure-sensitive adhesives. The 12 kinds of pressure-sensitive adhesives prepared were prepared into tapes and their performance was tested:

[0044] Preparation of adhesive tape: Use a 60μm thick wire rod to evenly apply the adhesive on the release paper, control the thickness of the final dry adhesive film to 20-30μm, place it in a blast oven at 80-100℃, dry it for 90-120 seconds, and then transfer it to the cotton paper substrate after drying. After lamination, place it in a 40℃ oven for 24 hours to stabilize, and then test the room temperature performance.

[0045] Test method: Test the initial adhesion of the rolling ball according to GB / T 4852-2002; test the sustained adhesion of the pressure-sensitive adhesive according to method A in GB / T 4851-2014; test the 180° peel strength of the pressure-sensitive adhesive according to GB / T 2792-2014; after preparing the tape, stick it on the skin for 8 hours, then remove it and observe whether the skin has any allergic reaction.

[0046] Table 1 Performance comparison table of examples and comparative examples

[0047]

[0048] Conclusion analysis:

[0049] Since the non-reactive emulsifier used in the latex stock solution in Comparative Example 1, and the wetting agent and thickener used in the later stage are all small molecule products, these three substances will precipitate during the use of the tape after being prepared. Therefore, no matter it is mixed with the thickening emulsion of the present invention or the commercially available thickening emulsion, the prepared pressure-sensitive adhesive tape will cause skin redness and allergy problems; while the use of the latex stock solution prepared by the present invention greatly reduces the problems of allergies and redness caused by the migration of small molecule additives.

[0050] By comparing the pressure-sensitive adhesive tapes with different tackifying emulsions, it is found that since the commercially available tackifying emulsions are all prepared by pre-emulsification after the tackifying resin is prepared, the prepared tackifying emulsions have a yellowish appearance, which causes the appearance of the tape to be yellowish and has a great impact on the initial adhesion. The tackifying emulsion selected by the present invention is light in color, the appearance of the prepared pressure-sensitive adhesive has no obvious hue, and has no obvious effect on the initial adhesion.

[0051] For those skilled in the art, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all of these changes and deformations should fall within the protection scope of the claims of the present invention.

Claims

1. A water-based acrylic pressure-sensitive adhesive, characterized in that: The aqueous acrylic emulsion rubber is prepared by mixing 100.0 parts of aqueous acrylic emulsion rubber and 20 parts of tackifying emulsion, wherein the tackifying emulsion is DERMULSENE TR602 of DRT, and the aqueous acrylic emulsion rubber is prepared by the following components in parts by weight: 40.0-50.0 parts of deionized water, 0.5-2.2 parts of emulsifier, 40.0-60.0 parts of butyl acrylate, 5.0-10.0 parts of methyl acrylate, 2.0-5.0 parts of methyl methacrylate, 1.0-2.0 parts of hydroxyethyl acrylate, 0.5-1.5 parts of β-carboxyethyl acrylate, 0.01-0.05 parts of mercaptan, 0.1-1.0 parts of initiator, 0.01-0.05 parts of redox agent, 0.01-0.05 parts of sodium bicarbonate, 3.0-5.0 parts of ammonia water and 4.0-7.0 parts of low surface tension solvent; the emulsifier is SR-10 and / or ER-20, and the low surface tension solvent is ethanol or isopropanol; The steps for preparing the aqueous acrylic emulsion raw rubber are as follows: S101, add some deionized water to container A, add emulsifier under stirring, disperse at high speed for 20-40 minutes, then add monomers butyl acrylate, methyl acrylate, methyl methacrylate, Hydroxyethyl acrylate, β-carboxyethyl acrylate and mercaptan are dispersed at high speed for 20-40 minutes to form a pre-emulsion; S102, take 2%-5% of the weight of the pre-emulsion prepared in step S101 as seeds, add them into container B together with the remaining deionized water and sodium bicarbonate, raise the temperature to 80-83°C, and then add part of the induction while adding the remaining initiator to the pre-emulsion in container A; S103, when there is obvious blue light in container B, it is determined that the initiation is successful. At this time, the temperature in container B is kept unchanged, and the pre-emulsion mixed with the initiator in container A is dripped into the container, and the dripping time is controlled within 3-4 hours; After the addition is completed, keep the temperature for 1 hour; after the temperature is reduced to 70-75°C, add a redox agent to remove residual monomers and keep the temperature for 30 minutes; S104. After the heat preservation is completed, the temperature is lowered to below 50°C, ammonia water is added to adjust the pH value to 7-8, and a low surface tension solvent is added. After stirring for 5.0-10.0 minutes, the latex rubber is obtained by filtering with a nylon filter.

2. The water-based acrylic pressure-sensitive adhesive according to claim 1, characterized in that: The initiator is ammonium persulfate or sodium persulfate.

3. The water-based acrylic pressure-sensitive adhesive according to claim 1, characterized in that: The redox agent is any one of tert-butyl peroxide, sodium formaldehyde sulfoxylate and sodium bisulfite.

4. The water-based acrylic pressure-sensitive adhesive according to claim 1, characterized in that: Step S101 The speed is 300rpm for medium and high speed dispersion.

5. The water-based acrylic pressure-sensitive adhesive according to claim 1, characterized in that: Step S104 The mesh size of the nylon filter is 300 mesh.

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