Modified acrylic pressure-sensitive adhesive and preparation method thereof

Abstract

The preparation method comprises the following steps: weighing 100 parts by weight of an acrylic monomer, 3-10 parts by weight of phenyl and vinyl-containing silicon resin, 0.5-1 part by weight of an anchoring agent, 0.5-1.5 parts by weight of a copolymerization photoinitiator and 0.05-0.1 part by weight of a free radical photoinitiator, and carrying out a polymerization reaction under a nitrogen atmosphere to obtain the modified acrylic pressure-sensitive adhesive. The preparation method comprises the following steps: uniformly stirring and mixing the acrylic monomer, the silicon resin containing phenyl and vinyl, the anchoring agent, the free radical photoinitiator and the copolymerized photoinitiator according to the formula ratio, discharging to obtain the modified acrylic pressure-sensitive adhesive, and curing the modified acrylic pressure-sensitive adhesive under a UV lamp when the modified acrylic pressure-sensitive adhesive is used. Starting from molecular structure design, silicon resin containing phenyl and vinyl is introduced into a polyacrylate molecular structure, and double initiators are adopted, so that the heat resistance, the water resistance, the adhesive force and the peel strength of the acrylic pressure-sensitive adhesive are improved.

Description

Technical Field

[0001] The invention relates to the field of pressure-sensitive adhesives, and in particular to a modified acrylic pressure-sensitive adhesive and a preparation method thereof. Background Art

[0002] Polyacrylate is a series of polymers with CC single bonds in the main chain and polar groups in the side chain, which are obtained by free radical polymerization between acrylic acid ester monomers or between acrylic acid ester monomers and olefin monomers in the presence of an initiator. It is a typical viscoelastic material that can be prepared into various adhesives and used in different fields.

[0003] Traditional polyacrylate pressure-sensitive adhesive (PSA) has a polar ester side chain, so it has good adhesion to materials with high surface polarity or high surface energy, such as metal plates, glass plates, PC plates, etc., but has poor adhesion to materials with low polarity and low surface energy, such as polypropylene (PP). The general existing method is: first apply a primer on the surface of the low surface energy material, and then bond after the primer is completely dry. The process is cumbersome, and the primer has a strong odor and is toxic. In addition, pure polyacrylate PSA is not heat-resistant and has poor water resistance. Summary of the invention

[0004] The purpose of the present invention is to provide a modified acrylic pressure-sensitive adhesive and a preparation method thereof in view of the deficiencies in the prior art. The present invention starts from the molecular structure design and introduces a silicone resin containing phenyl and vinyl into the molecular structure of polyacrylate to improve the heat resistance, water resistance, adhesion and peel strength of the acrylic pressure-sensitive adhesive.

[0005] The purpose of the present invention is achieved through the following technical solutions: First, the present invention provides a modified acrylic pressure-sensitive adhesive, comprising the following raw material components: 100 parts by weight of acrylic monomer, 3-10 parts by weight of silicone resin containing phenyl and vinyl, 0.5-1 parts by weight of anchoring agent, 0.5-1.5 parts by weight of copolymerization photoinitiator and 0.05-0.1 parts by weight of free radical photoinitiator.

[0006] Furthermore, the acrylic monomer includes a soft monomer, a hard monomer and a functional monomer; the mass ratio of the soft monomer, the hard monomer and the functional monomer is 70-85:10-20:5-10; The soft monomer is a mixture of tetraethylene glycol diacrylate and 2-hydroxyethyl acrylate and at least one of decyl acrylate, butyl acrylate and 2-ethylhexyl acrylate, wherein the tetraethylene glycol diacrylate accounts for 5-10% of the total mass of the soft monomer, and the 2-hydroxyethyl acrylate accounts for 10-20% of the total mass of the soft monomer; The hard monomer is at least one of methyl acrylate, vinyl acetate, and methyl methacrylate; The functional monomer is at least one of acrylic acid, 2-hydroxypropyl acrylate and isobornyl acrylate.

[0007] Furthermore, the copolymerization photoinitiator is 4-acryloxybenzophenone and / or 4-methacryloxybenzophenone.

[0008] Furthermore, the free radical photoinitiator is at least one of ethyl 2,4,6-trimethylbenzoylphenylphosphonate, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0009] Furthermore, the silicone resin containing phenyl and vinyl is prepared by the following method: dissolving trimethylsilanol in an appropriate amount of solvent, adding an appropriate amount of pure water, stirring for 5-10 minutes, adjusting the pH in the system to 3-4, heating to 70°C, slowly dropping vinyltrimethoxysilane and triethoxyphenylsilane, and maintaining the reaction at 60-90°C for 1-3 hours, cooling and washing with water, removing the solvent and water, and obtaining a silicone resin containing phenyl and vinyl.

[0010] Furthermore, the molar ratio of the vinyltrimethoxysilane, trimethylsilanol and triethoxyphenylsilane is 10:8-9:0.08-0.3.

[0011] Furthermore, the amount of pure water added is 4-5 times the total molar amount of vinyltrimethoxysilane, trimethylsilanol and triethoxyphenylsilane.

[0012] Furthermore, the anchoring agent is vinyl triacetoxy silane and / or glycidyl ether propoxy trimethoxy silane.

[0013] Second, the present invention also provides a method for preparing the modified acrylic pressure-sensitive adhesive, the specific process of which is as follows: Under a nitrogen atmosphere, the acrylic monomer, the silicone resin containing phenyl and vinyl, the anchoring agent, the free radical photoinitiator and the copolymerization photoinitiator in the formulated amount are stirred and mixed uniformly, and the material is discharged to obtain a modified acrylic pressure-sensitive adhesive, which is placed under a UV lamp for curing when used.

[0014] Furthermore, the light energy during curing is 300-800 mJ / cm 2 , the curing time is 120-300s.

[0015] Silicone resin is a polymer with a highly branched three-dimensional structure. As a widely used material, it has outstanding heat resistance, water resistance, UV resistance and improved adhesion. In addition, the Si-O-Si bond angle is 140° to 180°, which is higher than the COC bond angle of 110°, so silicon compounds have high flexibility.

[0016] Triethoxyphenylsilane contains phenyl groups, which impart thermal stability to the copolymer and increase its hydrophobicity. Therefore, the addition of triethoxyphenylsilane is beneficial to improving the water resistance of silicone resin, enhancing the wettability of the silicone resin surface to non-polar polymers, promoting interfacial adhesion, and improving the hydrophobicity and peel strength of PSA. With the addition of phenyl-containing silicone resin, the amount of non-polar methyl and phenyl groups in the polyacrylate molecular chain increases, and the silicone resin becomes highly hydrophobic, which increases the water drop angle of the adhesive from 96° to 113°. In addition, with the addition of triethoxyphenylsilane, due to the synergistic effect of inductive effect and steric effect, triethoxyphenylsilane exhibits lower reactivity, and the thermal stability of silicone resin increases accordingly.

[0017] The vinyl groups in the silicone resin can participate in the cross-linking reaction during the photoinitiation process, which can increase the degree of cross-linking of the pressure-sensitive adhesive after curing, ensuring that while the peeling force of the pressure-sensitive adhesive is increased, the stability and bulk strength of the pressure-sensitive adhesive are not affected.

[0018] The phenyl and vinyl groups introduced into the polyacrylate molecular structure of the present invention reduce the surface free energy and polarity of the acrylate polymer, increase the wettability of the pressure-sensitive adhesive to non-polar materials, thereby eliminating the need for a primer, giving the pressure-sensitive adhesive a high peeling force, and improving the wettability and peeling strength of the adhesive.

[0019] Anchoring agents are necessary additives in the use of pressure-sensitive adhesives. Generally, alkoxy, acyloxy, epoxy and other group silane coupling agents or related modified products are used as anchoring agents. During the aging process, especially under high temperature conditions, some unreacted groups in the anchoring agent may continue to react, thereby improving the adhesion between the pressure-sensitive adhesive and the substrate.

[0020] The present invention adopts a copolymer photoinitiator and a free radical photoinitiator as dual initiators. The copolymer photoinitiator is a copolymerizable photoinitiator containing ethyleneoxycarbonyl. The initiator participates in the crosslinking reaction, increases the molecular weight and viscosity of the synthetic acrylic PSA, and is combined with the free radical photoinitiator to achieve a good balance between the viscosity, peel adhesion and shear strength of the UV crosslinked acrylic PSA.

[0021] The invention starts from the molecular structure design, introduces silicone resin containing phenyl and vinyl into the molecular structure of polyacrylate, adopts double initiator, and improves the heat resistance, water resistance, adhesion and peeling strength of acrylic pressure-sensitive adhesive. DETAILED DESCRIPTION

[0022] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0023] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods, and the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0024] Example 1 Dissolve 73 parts by weight of trimethylsilanol in 100 parts by weight of ethyl acetate, add 135 parts by weight of pure water, stir for 10 minutes, adjust the pH in the system to 3.5 with concentrated hydrochloric acid, heat to 70°C, add 148.23 parts by weight of vinyltrimethoxysilane and 2.21 parts by weight of triethoxyphenylsilane dropwise over 120 minutes, and keep the reaction at 70°C for 2 hours. After cooling, wash with water until neutral, distill off ethyl acetate and water, and obtain a silicone resin containing phenyl and vinyl.

[0025] Under a nitrogen atmosphere, 8 parts by weight of tetraethylene glycol diacrylate, 30 parts by weight of 2-hydroxyethyl acrylate, 20 parts by weight of decyl acrylate, 17 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of methyl methacrylate, 8 parts by weight of vinyl acetate, 5 parts by weight of acrylic acid, 2 parts by weight of isobornyl acrylate, 10 parts by weight of a silicone resin containing phenyl and vinyl, 0.5 parts by weight of vinyl triacetoxysilane, 0.5 parts by weight of 4-acryloxybenzophenone, 0.05 parts by weight of ethyl 2,4,6-trimethylbenzoylphenylphosphonate and 0.05 parts by weight of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide were stirred and mixed uniformly, and the material was discharged to obtain a modified acrylic pressure-sensitive adhesive.

[0026] Example 2 Dissolve 59 parts by weight of trimethylsilanol in 100 parts by weight of ethyl acetate, add 135 parts by weight of pure water, stir for 10 minutes, adjust the pH in the system to 3.5 with concentrated hydrochloric acid, heat to 70°C, add 148.23 parts by weight of vinyltrimethoxysilane and 4.14 parts by weight of triethoxyphenylsilane dropwise over 120 minutes, and keep the reaction at 70°C for 2 hours. After cooling, wash with water until neutral, distill off ethyl acetate and water, and obtain a silicone resin containing phenyl and vinyl.

[0027] Under a nitrogen atmosphere, 12 parts by weight of tetraethylene glycol diacrylate, 25 parts by weight of 2-hydroxyethyl acrylate, 18 parts by weight of decyl acrylate, 15 parts by weight of butyl acrylate, 10 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of methyl methacrylate, 5 parts by weight of methyl acrylate, 5 parts by weight of 2-hydroxypropyl acrylate, 8 parts by weight of silicone resin containing phenyl and vinyl, 1 part by weight of glycidyl ether propoxy trimethoxy silane, 0.5 parts by weight of 4-acryloxy benzophenone, 0.5 parts by weight of 4-methacryloxy benzophenone, and 0.05 parts by weight of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide were stirred and mixed uniformly, and the material was discharged to obtain a modified acrylic pressure-sensitive adhesive.

[0028] Example 3 Dissolve 60 parts by weight of trimethylsilanol in 100 parts by weight of ethyl acetate, add 135 parts by weight of pure water, stir for 10 minutes, adjust the pH in the system to 3.5 with concentrated hydrochloric acid, heat to 70°C, add 148.23 parts by weight of vinyltrimethoxysilane and 6.25 parts by weight of triethoxyphenylsilane dropwise over 120 minutes, and keep the reaction at 70°C for 2 hours. After cooling, wash with water until neutral, distill off ethyl acetate and water, and obtain a silicone resin containing phenyl and vinyl.

[0029] Under a nitrogen atmosphere, 15 parts by weight of tetraethylene glycol diacrylate, 20 parts by weight of 2-hydroxyethyl acrylate, 28 parts by weight of decyl acrylate, 20 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of methyl methacrylate, 2 parts by weight of methyl acrylate, 5 parts by weight of isobornyl acrylate, 5 parts by weight of silicone resin containing phenyl and vinyl, 0.8 parts by weight of glycidyl ether propoxy trimethoxy silane, 0.5 parts by weight of 4-acryloxy benzophenone, 1 part by weight of 4-methacryloxy benzophenone, 0.04 parts by weight of ethyl 2,4,6-trimethylbenzoyl phenylphosphonate, and 0.04 parts by weight of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide were stirred and mixed uniformly, and the material was discharged to obtain a modified acrylic pressure-sensitive adhesive.

[0030] Comparative Example 1 Under a nitrogen atmosphere, 12 parts by weight of tetraethylene glycol diacrylate, 25 parts by weight of 2-hydroxyethyl acrylate, 18 parts by weight of decyl acrylate, 15 parts by weight of butyl acrylate, 10 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of methyl methacrylate, 5 parts by weight of methyl acrylate, 5 parts by weight of 2-hydroxypropyl acrylate, 8 parts by weight of vinyl trimethoxy silane, 1 part by weight of glycidyl ether propoxy trimethoxy silane, 0.5 parts by weight of 4-acryloxy benzophenone, 0.5 parts by weight of 4-methacryloxy benzophenone, and 0.05 parts by weight of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide were stirred and mixed uniformly, and the material was discharged to obtain a modified acrylic pressure-sensitive adhesive.

[0031] Comparative Example 2 Under a nitrogen atmosphere, 12 parts by weight of tetraethylene glycol diacrylate, 25 parts by weight of 2-hydroxyethyl acrylate, 18 parts by weight of decyl acrylate, 15 parts by weight of butyl acrylate, 10 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of methyl methacrylate, 5 parts by weight of methyl acrylate, 5 parts by weight of 2-hydroxypropyl acrylate, 8 parts by weight of triethoxyphenylsilane, 1 part by weight of glycidyl ether propoxytrimethoxysilane, 0.5 parts by weight of 4-acryloxybenzophenone, 0.5 parts by weight of 4-methacryloxybenzophenone, and 0.05 parts by weight of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide were stirred and mixed uniformly, and the material was discharged to obtain a modified acrylic pressure-sensitive adhesive.

[0032] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that no free radical photoinitiator is added to the modified acrylic pressure-sensitive adhesive.

[0033] Comparative Example 4 The difference between Comparative Example 4 and Example 2 is that no copolymerization photoinitiator is added to the modified acrylic pressure-sensitive adhesive.

[0034] The specific raw material components and component contents in Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table 1.

[0035] Table 1

[0036] The modified acrylic pressure-sensitive adhesive prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was coated on a PET release film with a thickness of 50 μm. The coating thickness of the modified acrylic pressure-sensitive adhesive was 25 μm. After coating, the modified acrylic pressure-sensitive adhesive was cured under a UV lamp. The light energy during curing was 400 mJ / cm 2 , curing time is 180s, later 50 o C After aging for three days, the aging pressure-sensitive adhesive was cut into 150mm*25mm test strips and the following tests were performed: 1. According to the GB / T 2792-2014 test standard, the 180° peeling force of the pressure-sensitive adhesive on the stainless steel plate and the PET single-sided tape at room temperature and 80°C was tested; 2. According to the GB / T4851-2014 test standard, the pressure-sensitive adhesive is tested for its adhesion to stainless steel plates and PET single-sided tape at room temperature and at 80°C; 3. Test the initial adhesion of pressure-sensitive adhesive at room temperature according to GB / T4852-2002 test standard; 4. Static contact angle test: Use an optical contact angle tester to test the hydrophobicity of the matured pressure-sensitive adhesive film, measure the contact angle of water droplets on the film surface, and take the average value after multiple measurements.

[0037] The test results are shown in Table 2.

[0038] Table 2

[0039] According to the disclosure of the above description, those skilled in the art to which the present invention belongs may also make appropriate changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A modified acrylic pressure-sensitive adhesive, characterized in that: The invention comprises the following raw material components: 100 parts by weight of acrylic monomer, 3-10 parts by weight of silicone resin containing phenyl and vinyl, 0.5-1 parts by weight of anchoring agent, 0.5-1.5 parts by weight of copolymerization photoinitiator and 0.05-0.1 parts by weight of free radical photoinitiator.

2. The modified acrylic pressure-sensitive adhesive according to claim 1, characterized in that: The acrylic monomer includes a soft monomer, a hard monomer and a functional monomer; the mass ratio of the soft monomer, the hard monomer and the functional monomer is 70-85:10-20:5-10; The soft monomer is a mixture of tetraethylene glycol diacrylate and 2-hydroxyethyl acrylate and at least one of decyl acrylate, butyl acrylate and 2-ethylhexyl acrylate, wherein the tetraethylene glycol diacrylate accounts for 5-10% of the total mass of the soft monomer, and the 2-hydroxyethyl acrylate accounts for 10-20% of the total mass of the soft monomer; The hard monomer is a mixture of methyl methacrylate and methyl acrylate and / or vinyl acetate; The functional monomer is at least one of acrylic acid, 2-hydroxypropyl acrylate and isobornyl acrylate.

3. The modified acrylic pressure-sensitive adhesive according to claim 1, characterized in that: The copolymerized photoinitiator is 4-acryloxybenzophenone and / or 4-methacryloxybenzophenone.

4. The modified acrylic pressure-sensitive adhesive according to claim 1, characterized in that: The free radical photoinitiator is at least one of ethyl 2,4,6-trimethylbenzoylphenylphosphonate, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

5. The modified acrylic pressure-sensitive adhesive according to claim 1, characterized in that: The silicone resin containing phenyl and vinyl is prepared by the following method: Dissolve trimethylsilanol in a proper amount of solvent, add a proper amount of purified water, stir for 5-10 minutes, adjust the pH of the system to 3-4, heat to 70°C, drop vinyltrimethoxysilane and triethoxyphenylsilane, and keep the reaction at 60-90°C for 1-3 hours. After cooling, wash with water, remove the solvent and water, and obtain a silicone resin containing phenyl and vinyl.

6. The modified acrylic pressure-sensitive adhesive according to claim 5, characterized in that: The molar ratio of the vinyl trimethoxysilane, trimethylsilanol and triethoxyphenylsilane is 10:8-9:0.08-0.

3.

7. The modified acrylic pressure-sensitive adhesive according to claim 5, characterized in that: The amount of pure water added is 4-5 times the total molar amount of vinyltrimethoxysilane, trimethylsilanol and triethoxyphenylsilane.

8. The modified acrylic pressure-sensitive adhesive according to claim 1, characterized in that: The anchoring agent is vinyl triacetoxy silane and / or glycidyl ether propoxy trimethoxy silane.

9. The method for preparing the modified acrylic pressure-sensitive adhesive according to any one of claims 1 to 8, characterized in that: Under a nitrogen atmosphere, the acrylic monomer, the silicone resin containing phenyl and vinyl, the anchoring agent, the free radical photoinitiator and the copolymerization photoinitiator in the formulated amount are stirred and mixed uniformly, and the material is discharged to obtain a modified acrylic pressure-sensitive adhesive, which is placed under a UV lamp for curing when used.

10. The method for preparing the modified acrylic pressure-sensitive adhesive according to claim 9, characterized in that: The light energy during curing is 300-800mJ / cm 2 , the curing time is 120-300s.

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