Single-component post-crosslinking water-based acrylic pressure-sensitive adhesive and preparation method and use method thereof

Abstract

This invention relates to the field of waterborne adhesives, and in particular to a single-component post-crosslinking waterborne acrylic pressure-sensitive adhesive, its preparation method, and its application method. The raw materials are 100 parts deionized water, 0.1-10 parts of blocked polymerizable crosslinking points, 50-90 parts of butyl acrylate and / or isooctyl acrylate, 10-40 parts of methyl acrylate and / or methyl methacrylate, 0.1-10 parts of hydroxyethyl acrylate and / or hydroxyethyl methacrylate, 0.1-10 parts of acrylic acid and / or methacrylic acid, 0.1-1 parts of oil-soluble peroxide oxidation initiator, 0.1-1 parts of water-soluble ascorbic acid or hyposulfite reduction initiator, 0.1-10 parts of alkylphenol / fatty alcohol polyether emulsifier, 0.1-10 parts of succinate monoester sulfonate emulsifier, 0.1-1 parts of bicarbonate, and an appropriate amount of softened water. The adhesive is prepared by monomer pre-emulsification followed by a redox initiation step under nitrogen protection at 50-70°C.

Description

Technical Field

[0001] This invention relates to the field of waterborne adhesives technology, specifically to a method for preparing a single-component post-crosslinking waterborne acrylic pressure-sensitive adhesive. Background Technology

[0002] Currently, to improve the adhesion between the adhesive film and the substrate of adhesive tapes and to enhance their long-term adhesion and resistance to delamination, the water-based acrylic pressure-sensitive adhesives used in their application need to be compounded with polyaziridine or polycarboimide curing agents before coating and subsequent curing. The adhesive compounded with the curing agent must be used within a certain timeframe; otherwise, the curing agent will become ineffective, thus limiting production. Therefore, the industry urgently needs a single-component post-crosslinking adhesive that can be stored for a long time.

[0003] Existing techniques for preparing one-component crosslinked waterborne pressure-sensitive adhesives typically employ N-hydroxymethylacrylamide or DAAM / ADH. However, this crosslinking technique is characterized by the crosslinking reaction occurring during the adhesive drying process, and it takes place in an aqueous phase. Consequently, the resulting protective film exhibits poor adhesion to the substrate, making it prone to detachment after prolonged application.

[0004] For example, CN201210583488.6 discloses a one-component waterborne pressure-sensitive adhesive for sun protection and heat insulation films. This adhesive undergoes copolymerization modification by introducing fluorinated vinyl monomers during the polymerization process. The functional monomers used are any one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxymethylacrylamide, acrylamide, and glycidyl methacrylate; the crosslinking monomers used are any one or more of diacetone acrylamide, acetoacetoxyethyl methacrylate, and acetoacetoxyethyl acrylate. This technology uses fluorinated monomers for copolymerization modification, resulting in higher product costs. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a single-component, post-crosslinked, waterborne acrylic pressure-sensitive adhesive, its preparation method, and its application method. This invention introduces closed polymerizable crosslinking points during the polymerization process, allowing the crosslinking points and reactive functional groups to coexist for a long time in the emulsion system. After coating and drying, the crosslinking points gradually unblock and react with the reactive functional groups during the subsequent curing process to achieve the crosslinking effect.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a one-component post-crosslinking waterborne acrylic pressure-sensitive adhesive: the raw materials are 100 parts deionized water, 0.1-10 parts of blocked polymerizable crosslinking points, 50-90 parts of butyl acrylate and / or isooctyl acrylate, 10-40 parts of methyl acrylate and / or methyl methacrylate, 0.1-10 parts of hydroxyethyl acrylate and / or hydroxyethyl methacrylate, 0.1-10 parts of acrylic acid and / or methacrylic acid, 0.1-1 parts of oil-soluble peroxide oxidation initiator, 0.1-1 parts of water-soluble ascorbic acid or hyposulfite reduction initiator, 0.1-10 parts of alkylphenol / fatty alcohol polyether emulsifier, 0.1-10 parts of succinate monoester sulfonate emulsifier, 0.1-1 parts of bicarbonate, and an appropriate amount of softened water. The adhesive is prepared by monomer pre-emulsification and oxidation-reduction initiation under nitrogen protection at 50-70℃.

[0008] Specifically, the steps include: (1) preparing closed polymerizable crosslinking points; (2) pre-emulsification; and (3) emulsion polymerization.

[0009] The method for preparing the blocked polymerizable crosslinking points involves reacting (meth)acrylic acid with an excess of polyaziridine or polycarboimide in a specific molar ratio to generate a molecule containing a free radical polymerizable double bond and crosslinkable aziridine or carboimide functional groups. The remaining aziridine or carboimide is then completely blocked using the blocking agent methyl ethyl ketone oxime. The molar ratio of the functional groups of the acrylic acid and / or methacrylic acid to the aziridine or carboimide is 1:2. The deblocking temperature of the blocked polymerizable crosslinking points is 100-150°C.

[0010] Specifically, the pre-emulsification involves dissolving an emulsifier in deionized water, and then adding, under stirring, closed polymerizable crosslinking sites, butyl acrylate and / or isooctyl acrylate, methyl acrylate and / or methyl methacrylate, hydroxyethyl acrylate and / or hydroxyethyl methacrylate, acrylic acid and / or methacrylic acid, and an oil-soluble peroxide oxidation initiator to obtain a pre-emulsified monomer mixture.

[0011] Specifically, the emulsion polymerization involves first adding a certain amount of softened water and a small amount of pre-emulsion to the reactor, heating it to 50-70°C, adding a portion of the reduction initiator to form seeds, and then simultaneously adding the remaining pre-emulsion and reduction initiator over 2-4 hours. After the addition is complete, the mixture is kept at the temperature for 0.5-2 hours.

[0012] Furthermore, after the emulsion polymerization is completed, the temperature is lowered to below 45°C, and then 0.1 parts of defoamer, 0.2 parts of OT75 and 1 part of ammonia are added and stirred evenly to obtain a single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive.

[0013] The method of using the single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive of the present invention is as follows: the single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive is coated on a PE film, the moisture is dried at 100~120℃, and the film is cured at 40℃ for 3 days.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] The single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive prepared by the method of this invention exhibits comparable adhesion and anti-debonding properties to the substrate as the two-component post-crosslinked pressure-sensitive adhesive. Furthermore, it can be stored for extended periods, overcoming the time-limited limitations of two-component crosslinked waterborne pressure-sensitive adhesives.

[0016] The single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive prepared by this invention, when coated with a PE film, dried at high temperature and cured for 3 days, exhibits better adhesion to the substrate and better adhesion to the steel plate after being left to peel off at 50°C for 7 days than the DAAM / ADH crosslinking technology, and is comparable to the effect of aziridine or carboimide post-crosslinking technology. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1

[0019] A method for preparing a one-component post-crosslinked waterborne acrylic pressure-sensitive adhesive, comprising the following steps:

[0020] (1) Preparation of blocked polyaziridine polymerizable crosslinking points: 1 mol of acrylic acid was slowly added dropwise to a polyaziridine curing agent with 2 mol of aziridine functional groups at 50℃ with stirring and anhydrous conditions for 3 h. After 1 h of temperature preservation, 1.1 mol of methyl ethyl acetone oxime was added dropwise for 1 h. After 1 h of temperature preservation, the blocked aziridine polymerizable crosslinking points were obtained.

[0021] (2) Dissolve 1 part of OP-10 and 1 part of A-102 emulsifier in 12 parts of softened water, and add the following monomers under stirring conditions: 5 parts of blocking polyaziridine polymerizable crosslinking points, 35 parts of butyl acrylate, 5 parts of isooctyl acrylate, 5 parts of methyl methacrylate, 1 part of hydroxyethyl acrylate, 1 part of acrylic acid and 1 part of benzoyl peroxide to obtain a pre-emulsion.

[0022] (3) Dissolve 1 part of ascorbic acid in 5 parts of deionized water to obtain a reduction initiator solution for later use;

[0023] (4) First, add 23 parts softened water, 0.1 parts ammonium bicarbonate and 8% of the total mass of pre-emulsion to the reactor, purge with nitrogen and heat to 60°C, then add 10% of the total mass of the initiator solution, and then simultaneously add the remaining pre-emulsion and initiator solution for 3 hours, and keep warm for 1 hour after the addition is complete.

[0024] (5) Cool down to below 45°C, then add 0.1 parts mineral oil defoamer, 0.2 parts OT75 and 1 part ammonia water, stir evenly to obtain the single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive.

[0025] Preparation of the tape: The prepared single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive was coated on a PE film, dried at 100~120℃, and cured at 40℃ for 3 days.

[0026] Example 2

[0027] A method for preparing a one-component post-crosslinked waterborne acrylic pressure-sensitive adhesive, comprising the following steps:

[0028] (1) Preparation of blocked polycarbodiimide-type polymerizable crosslinking points: Under the conditions of stirring and anhydrous conditions at 50°C, 1 mol of acrylic acid was slowly added dropwise to a polyaziridine curing agent with 2 mol of aziridine functional groups for 3 h, and the temperature was maintained for 1 h. Then, 1.1 mol of methyl ethyl acetone oxime was added dropwise for 1 h, and the temperature was maintained for 1 h to obtain blocked aziridine-type polymerizable crosslinking points.

[0029] (2) Dissolve 0.5 parts of OP-10 and 1.5 parts of A-102 emulsifier in 12 parts of softened water, and add the following monomers under stirring conditions: 5 parts of blocked polycarbodiimide polymerizable crosslinking points, 30 parts of butyl acrylate, 10 parts of isooctyl acrylate, 5 parts of methyl acrylate, 1 part of hydroxyethyl acrylate, 1 part of acrylic acid and 1 part of benzoyl peroxide to obtain a pre-emulsion.

[0030] (3) Dissolve 1 part of ascorbic acid in 5 parts of deionized water to obtain a reduction initiator solution for later use;

[0031] (4) First, add 23 parts softened water, 0.1 parts ammonium bicarbonate and 8% of the total mass of pre-emulsion to the reactor, purge with nitrogen and heat to 60°C, then add 10% of the total mass of the initiator solution, and then simultaneously add the remaining pre-emulsion and initiator solution for 3 hours, and keep warm for 1 hour after the addition is complete.

[0032] (5) Cool down to below 45°C, then add 0.1 parts mineral oil defoamer, 0.2 parts OT75 and 1 part ammonia water, stir evenly to obtain the single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive.

[0033] Preparation of the tape: The prepared single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive was coated on a PE film, dried at 100~120℃, and cured at 40℃ for 3 days.

[0034] Example 3

[0035] A method for preparing a one-component post-crosslinked waterborne acrylic pressure-sensitive adhesive, comprising the following steps:

[0036] (1) Preparation of blocked polycarboimide polymerizable crosslinking points: Under the conditions of stirring and anhydrous conditions at 50°C, 1 mol of acrylic acid was slowly added dropwise to a polycarboimide curing agent with 2 mol of carboimide functional groups for 3 hours and kept at the temperature for 1 hour. Then, 1.1 mol of methyl ethyl acetone oxime was added dropwise for 1 hour and kept at the temperature for 1 hour to obtain blocked polycarboimide polymerizable crosslinking points.

[0037] (2) Dissolve 1.5 parts of OP-10 and 0.5 parts of A-102 emulsifier in 12 parts of softened water, and add the following monomers under stirring conditions: 5 parts of blocked polycarbodiimide polymerizable crosslinking points, 30 parts of butyl acrylate, 10 parts of isooctyl acrylate, 5 parts of methyl acrylate, 1 part of hydroxyethyl acrylate, 1 part of acrylic acid and 1 part of benzoyl peroxide to obtain a pre-emulsion.

[0038] (3) Dissolve 1 part of sodium formaldehyde sulfoxylate in 5 parts of deionized water to obtain a reduction initiator solution for later use;

[0039] (4) First, add 23 parts softened water, 0.1 parts ammonium bicarbonate and 8% of the total mass of pre-emulsion to the reactor, purge with nitrogen and heat to 60°C, then add 10% of the total mass of the initiator solution, and then simultaneously add the remaining pre-emulsion and initiator solution for 3 hours, and keep warm for 1 hour after the addition is complete.

[0040] (5) Cool down to below 45°C, then add 0.1 parts mineral oil defoamer, 0.2 parts OT75 and 1 part ammonia water, stir evenly to obtain the single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive.

[0041] Preparation of the tape: The prepared single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive was coated on a PE film, dried at 100~120℃, and cured at 40℃ for 3 days.

[0042] The adhesion properties of the single-component post-crosslinked waterborne acrylic pressure-sensitive adhesives prepared in Examples 1-3 were compared with those of DAAM / ADH crosslinked pressure-sensitive adhesives, polyaziridine post-crosslinked pressure-sensitive adhesives, and non-crosslinked conventional pressure-sensitive adhesives.

[0043] The testing method was as follows: The coated PE tape was adhered to a steel plate and placed in a 70℃ oven for 7 days. After being removed and left at room temperature for 24 hours, it was peeled off at a speed of 300 m / min in a 180° direction. The residual adhesive area remaining on the steel plate was measured as the ratio of the area of ​​the peeled tape to the area of ​​the steel plate. The results are shown in the table below.

[0044]

[0045] In addition, the single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive prepared by this invention showed no residue after being stored for three months, coated with PE film tape, and pasted onto a steel plate at 70°C for 7 days. This indicates that the product can be stored for a long time, overcoming the time limitation of two-component crosslinked waterborne pressure-sensitive adhesives. In contrast, the polyaziridine post-crosslinked pressure-sensitive adhesive showed an 80% residue rate after being stored for 3 days, coated with PE film tape, and pasted onto a steel plate at 70°C for 7 days, indicating a short storage time.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive, characterized in that: The raw materials are 100 parts deionized water, 0.1-10 parts of blocked polymerizable crosslinking points, 50-90 parts of butyl acrylate and / or isooctyl acrylate, 10-40 parts of methyl acrylate and / or methyl methacrylate, 0.1-10 parts of hydroxyethyl acrylate and / or hydroxyethyl methacrylate, 0.1-10 parts of acrylic acid and / or methacrylic acid, 0.1-1 parts of oil-soluble peroxide oxidation initiator, 0.1-1 parts of water-soluble ascorbic acid or hyposulfite reduction initiator, 0.1-10 parts of alkylphenol / fatty alcohol polyether emulsifier, 0.1-10 parts of succinate monoester sulfonate emulsifier, 0.1-1 parts of bicarbonate, and an appropriate amount of softened water. It is prepared by monomer pre-emulsification and oxidation-reduction initiation step under nitrogen protection at 50-70℃. The process includes the following steps: (1) preparing closed polymerizable crosslinking sites; (2) pre-emulsification; and (3) emulsion polymerization. The method for preparing the closed polymerizable crosslinking points is as follows: reacting a certain molar ratio of acrylic acid and / or methacrylic acid with an excess of polyaziridine or polycarboimide to generate a molecule containing a free radical polymerizable double bond and a crosslinkable aziridine or carboimide functional group, and then completely blocking the remaining aziridine or carboimide with the blocking agent methyl ethyl ketone oxime.

2. The method for preparing a single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive according to claim 1, characterized in that: The molar ratio of the functional groups of the acrylic acid and / or methacrylic acid to aziridine or carboimide is 1:

2.

3. The method for preparing a single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive according to claim 1, characterized in that: The unsealing temperature of the closed polymerizable crosslinking points is 100~150℃.

4. The method for preparing a single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive according to claim 1, characterized in that: The pre-emulsification specifically involves dissolving the emulsifier in deionized water, and then adding, under stirring, closed polymerizable crosslinking sites, butyl acrylate and / or isooctyl acrylate, methyl acrylate and / or methyl methacrylate, hydroxyethyl acrylate and / or hydroxyethyl methacrylate, acrylic acid and / or methacrylic acid, and an oil-soluble peroxide oxidation initiator to obtain a pre-emulsified monomer mixture.

5. The method for preparing a single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive according to claim 1, characterized in that: The emulsion polymerization process involves first adding a certain amount of softened water and a small amount of pre-emulsion to the reactor, heating it to 50-70°C, adding a portion of the reduction initiator to form seeds, and then simultaneously adding the remaining pre-emulsion and reduction initiator over 2-4 hours. After the addition is complete, the mixture is kept at the temperature for 0.5-2 hours.

6. The method for preparing a single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive according to claim 1, characterized in that: After the emulsion polymerization is completed, the temperature is lowered to below 45°C, and then 0.1 parts of defoamer, 0.2 parts of OT75 and 1 part of ammonia are added and stirred evenly to obtain a single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive.

7. The single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive prepared by any of the preparation methods described in claims 1-6.

8. The method of using the single-component post-crosslinking waterborne acrylic pressure-sensitive adhesive according to claim 7, characterized in that: The single-component post-crosslinked waterborne acrylic pressure-sensitive adhesive was coated onto the PE film, dried at 100~120℃, and cured at 40℃ for 3 days.

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