Low-temperature-resistant rubber modified acrylate pressure-sensitive adhesive as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of adhesives, and particularly relates to a low-temperature-resistant rubber modified acrylate pressure-sensitive adhesive as well as a preparation method and application thereof. The low-temperature-resistant rubber modified acrylate pressure-sensitive adhesive is prepared from the following raw materials: a monomer, rubber, an initiator, tackifying resin and an organic solvent. According to the low-temperature-resistant rubber modified acrylate pressure-sensitive adhesive provided by the invention, the rubber is introduced as a raw material, reasonable formula design is performed, and the rubber and the acrylate pressure-sensitive adhesive are combined, so that the low-temperature resistance can be improved, the bonding strength of the pressure-sensitive adhesive can be improved, the production cost is reduced, and the market demand is met.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular relates to a low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive and a preparation method and application thereof. Background Art

[0002] In the adhesive field, acrylic pressure-sensitive adhesives are widely favored for their good adhesion, transparency and processing performance. However, with the continuous expansion of application areas, especially the increasing demand for applications in extreme low temperature environments, the low temperature resistance of traditional acrylic pressure-sensitive adhesives can no longer meet market demand.

[0003] In order to improve the low temperature resistance of acrylic pressure-sensitive adhesives, the industry usually adopts the method of introducing special monomers for modification. Although these special monomers, such as fluorine-containing monomers and siloxane monomers, can improve the low temperature resistance of pressure-sensitive adhesives to a certain extent, their complex preparation process and high raw material costs lead to high product prices, which limits their wide application.

[0004] In view of the above problems, the present invention aims to provide an economical and effective solution to improve the low temperature resistance of acrylic pressure-sensitive adhesive while improving its bonding performance. Summary of the invention

[0005] The purpose of the present invention is to provide a low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive and a preparation method and application thereof. By introducing rubber as a raw material and carrying out a reasonable formula design, the rubber and the acrylate pressure-sensitive adhesive are combined, which can not only achieve the improvement of low-temperature resistance, but also improve the bonding strength of the pressure-sensitive adhesive, while reducing production costs and meeting market demand.

[0006] A low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive, the preparation raw materials of which include monomers, rubber, initiator, tackifying resin and organic solvent.

[0007] Preferably, the monomers include soft monomers, hard monomers, and cross-linking monomers.

[0008] Preferably, the soft monomer includes one or more of butyl acrylate, n-octyl acrylate, and isooctyl acrylate; further preferably, it is butyl acrylate.

[0009] Preferably, the hard monomer includes one or more of styrene, methyl methacrylate, and vinyl acetate; more preferably, it is methyl methacrylate.

[0010] Preferably, the cross-linking monomer includes one or more of acrylic acid, hydroxyethyl acrylate, and glycidyl methacrylate; more preferably, it is hydroxyethyl acrylate.

[0011] Preferably, the mass ratio of the soft monomer, the hard monomer and the cross-linking monomer is (20-24):1:(1-3); more preferably, it is 22:1:2.

[0012] The inventors found that by selecting specific soft monomers, hard monomers, and cross-linking monomers, and adjusting the proportion of each component, the low temperature resistance of the pressure-sensitive adhesive can be improved while improving the adhesive performance. This is because there is a synergistic effect between these monomers. The flexibility and wettability of butyl acrylate help the pressure-sensitive adhesive to better contact the surface of the adherend and form a firm bond, while the strength and hardness of methyl methacrylate ensure the stability and durability of the bonded joint. The two work together to ensure that the pressure-sensitive adhesive has sufficient strength to cope with various stress conditions while maintaining flexibility. Hydroxyethyl acrylate forms cross-linking points between the molecular chains of the pressure-sensitive adhesive through its functional groups. These cross-linking points can limit the movement of the molecular chains at low temperatures, thereby preventing the pressure-sensitive adhesive from becoming brittle or losing its adhesive properties due to temperature reduction. At the same time, the flexibility of butyl acrylate helps to alleviate the rigidity brought by the cross-linking structure, so that the pressure-sensitive adhesive still has good flexibility and processability while maintaining low temperature resistance. The reasonable proportion and interaction of these three monomers in the formula make the pressure-sensitive adhesive show excellent performance in terms of adhesive performance, low temperature resistance, etc.

[0013] Preferably, the rubber is one or more of natural rubber, isobutylene rubber, styrene-butadiene thermoplastic elastomer, styrene-isoprene thermoplastic elastomer, butyl rubber, nitrile rubber, and liquid isoprene rubber; further preferably, it is natural rubber, butyl rubber, and liquid isoprene rubber.

[0014] Preferably, the mass ratio of the natural rubber, butyl rubber and liquid isoprene rubber is (3-5):1:(1-3); more preferably, it is 4:1:2.

[0015] Preferably, the natural rubber has an initial plasticity value of 42-46, a plasticity retention rate of 63%-67%, and an impurity content of ≤0.03%.

[0016] Preferably, the butyl rubber has a volatile matter of ≤0.5%, a Mooney viscosity of 28-34 at a test temperature of 125° C. (using a large rotor for preheating for 1 minute and then testing for 8 minutes), and an ash content of ≤0.7%.

[0017] In some preferred embodiments, the natural rubber and butyl rubber are both purchased from Shanghai Cunsi Industrial Co., Ltd.

[0018] Preferably, the molecular weight of the liquid isoprene rubber is 20,000-40,000, and the viscosity at room temperature is 55-65 Pa·s; further preferably, the molecular weight of the liquid isoprene rubber is 30,000, and the viscosity at room temperature is 60 Pa·s.

[0019] In some preferred embodiments, the liquid isoprene rubber is purchased from Shenzhen Masni Elastomer Co., Ltd.

[0020] Preferably, the added amount of the rubber is 3% to 5% of the monomer mass.

[0021] The inventor found that by selecting specific natural rubber, butyl rubber, liquid isoprene rubber as raw materials, the adhesive properties and low temperature resistance of the pressure-sensitive adhesive can be further improved, and the viscosity of the pressure-sensitive adhesive can also be adjusted. This may be because natural rubber provides good flexibility and initial adhesion, butyl rubber enhances the cohesion and aging resistance of the glue, and liquid isoprene rubber further improves the flexibility and fluidity of the glue, by adjusting the ratio of natural rubber, butyl rubber and liquid isoprene rubber, the three components can be made to have a synergistic effect, while achieving a balance between flexibility and fluidity, the cohesion and durability of the pressure-sensitive adhesive are further enhanced, so that the pressure-sensitive adhesive can still maintain good adhesion and cohesion under low temperature conditions, and improve its overall performance. In addition, the high fluidity of liquid isoprene rubber helps to regulate the viscosity of the pressure-sensitive adhesive, making it more suitable for different coating processes, and the addition of natural rubber and butyl rubber enables the pressure-sensitive adhesive to have better fluidity and coating performance while maintaining high adhesion and cohesion, and the combination of the three makes the pressure-sensitive adhesive more flexible and easy to operate in practical applications.

[0022] Preferably, the initiator is one or both of azobisisobutyronitrile and dibenzoyl peroxide; further preferably, it is dibenzoyl peroxide.

[0023] Preferably, the added amount of the initiator is 0.5% to 2% of the monomer mass.

[0024] Preferably, the tackifying resin is one or more of an aqueous rosin tackifying emulsion and an aqueous terpene tackifying emulsion; further preferably, it is an aqueous rosin tackifying emulsion and an aqueous terpene tackifying emulsion.

[0025] Preferably, the mass ratio of the aqueous rosin tackifying emulsion to the aqueous terpene tackifying emulsion is (1-3):1; more preferably, it is 2:1.

[0026] Preferably, the aqueous rosin tackifying emulsion has a viscosity of 100-400 mPa·s at room temperature, a solid content of 55±2%, and a pH value of 6-8.

[0027] Preferably, the aqueous terpene thickening emulsion has a viscosity of 600-800 mPa·s at room temperature, a solid content of 60±2%, and a pH value of 6-8.

[0028] In some preferred embodiments, the aqueous rosin tackifying emulsion and the aqueous terpene tackifying emulsion are both purchased from Shenzhen Yoshida Chemical Co., Ltd., models 958 and 968.

[0029] Preferably, the added amount of the tackifying resin is 4% to 6% of the monomer mass.

[0030] The inventors found that by selecting specific aqueous rosin tackifying emulsion and aqueous terpene tackifying emulsion as tackifying resin, the bonding effect of the pressure-sensitive adhesive can be further improved, and its solid content and viscosity can also be adjusted. This is because there is a significant synergistic effect between the two aqueous tackifying emulsions. The active functional groups in the rosin and terpene molecules can interact with each other to form a more complex and stable cross-linked network structure, which not only enhances the cohesion and adhesion of the pressure-sensitive adhesive, but also significantly improves its weather resistance. At the same time, the synergistic effect of the two tackifying emulsions can also effectively adjust the viscosity and solid content of the pressure-sensitive adhesive, so that the final product can meet the needs of different applications. In addition, this synergistic effect can also optimize the wettability and permeability of the pressure-sensitive adhesive, making it easier to form a good bonding interface with the surface of the adherend, thereby further improving the bonding effect.

[0031] Preferably, the organic solvent includes one or two of ethyl acetate and methanol; further preferably, ethyl acetate and methanol.

[0032] Preferably, the mass ratio of ethyl acetate to methanol is (30-35):1; more preferably, it is 97:3.

[0033] Preferably, the mass ratio of the organic solvent to the monomer is (1.5-1):1.

[0034] The inventors found that by selecting a specific ratio of ethyl acetate and methanol as organic solvents, the low temperature resistance of the pressure-sensitive adhesive can be improved, and the viscosity and solid content can be adjusted. This may be because on the one hand, methanol, due to its lower boiling point and high polarity, helps to maintain the fluidity of the pressure-sensitive adhesive under low temperature conditions, preventing the colloid from hardening or embrittlement caused by temperature reduction, while ethyl acetate ensures the uniform distribution of each component in the pressure-sensitive adhesive at low temperatures through its good organic solventization effect, avoiding the performance degradation caused by component separation. The synergistic effect of the two significantly improves the low temperature resistance of the pressure-sensitive adhesive, so that it can still maintain a good bonding effect under extreme low temperature conditions. On the other hand, the ratio of ethyl acetate and methanol has a direct impact on the viscosity of the pressure-sensitive adhesive. The addition of methanol can reduce the viscosity of the system, making the pressure-sensitive adhesive easier to apply and process. And ethyl acetate can increase the cohesion of the system and improve the viscosity of the pressure-sensitive adhesive. By accurately adjusting the ratio of the two, accurate control of the viscosity of the pressure-sensitive adhesive can be achieved. In addition, the synergistic compounding of ethyl acetate and methanol not only helps to control the volatilization rate of organic solvents in the pressure-sensitive adhesive, but also can affect the molecular arrangement and degree of cross-linking in the colloid. By adjusting the ratio of the two, the solid content of the pressure-sensitive adhesive can be precisely adjusted, thereby optimizing its physical properties and bonding properties.

[0035] The preparation method of the low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive comprises the following steps: S1. Separate the organic solvent into organic solvent 1 and organic solvent 2, dissolve the rubber in organic solvent 1, add the monomer, stir and heat to 80-90° C., and obtain liquid 1; S2, adding the initiator into the organic solvent 2 and stirring evenly to prepare an initiator solution; S3. Keep the temperature of liquid 1 at 80-90°C, add the initiator solution dropwise into liquid 1 within 2-3 hours, keep it at 80-90°C for 1-2 hours, then cool it to 30-50°C, add the tackifying resin, continue stirring for 15-30 minutes, and filter it.

[0036] Preferably, the amount of the organic solvent added is 60% to 70% of the total mass of the organic solvent.

[0037] Application of the low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive in the adhesive field.

[0038] Compared with the prior art, the advantages and beneficial effects of the present invention are: 1. The present invention provides a low-temperature resistant rubber-modified acrylic pressure-sensitive adhesive. By introducing rubber as a raw material and performing a reasonable formula design, the rubber and the acrylic pressure-sensitive adhesive are combined, which can not only achieve the improvement of low-temperature resistance, but also improve the bonding strength of the pressure-sensitive adhesive, while reducing production costs and meeting market demand.

[0039] 2. The present invention can improve the low temperature resistance of the pressure-sensitive adhesive while improving its bonding performance by selecting specific soft monomers, hard monomers, and cross-linking monomers and adjusting the proportions of each component.

[0040] 3. The present invention can further improve the adhesive performance and low temperature resistance of the pressure-sensitive adhesive and can also adjust the viscosity of the pressure-sensitive adhesive by selecting specific natural rubber, butyl rubber and liquid isoprene rubber as raw materials.

[0041] 4. The present invention can further improve the bonding effect of the pressure-sensitive adhesive and adjust its solid content and viscosity by selecting specific water-based rosin tackifying emulsion and water-based terpene tackifying emulsion as tackifying resins. This is because the two water-based tackifying emulsions have a significant synergistic effect.

[0042] 5. The present invention can improve the low temperature resistance of the pressure-sensitive adhesive and adjust the viscosity and solid content by selecting ethyl acetate and methanol in a specific ratio as the organic solvent. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] The raw materials used in the present invention are all commercially available, specifically: Natural rubber, initial plasticity is 42~46, plasticity retention is 63%~67%, impurity content is ≤0.03%; butyl rubber has a volatile matter of ≤0.5%, at a test temperature of 125°C, it is preheated for 1 minute using a large rotor and then tested for 8 minutes, the Mooney viscosity is 28~34, and the ash content is ≤0.7%; all were purchased from Shanghai Cunsi Industrial Co., Ltd.

[0045] Liquid isoprene rubber, with a molecular weight of 30,000 and a viscosity of 60 Pa·s at room temperature, was purchased from Shenzhen Masni Elastomer Co., Ltd.

[0046] The viscosity of the aqueous rosin tackifying emulsion at room temperature is 100~400mPa·s, the solid content is 55±2%, and the pH value is 6~8; the viscosity of the aqueous terpene tackifying emulsion at room temperature is 600~800mPa·s, the solid content is 60±2%, and the pH value is 6~8; both were purchased from Shenzhen Yoshida Chemical Co., Ltd., models 958 and 968.

[0047] Example 1 This embodiment provides a low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive, the raw materials for preparing the rubber-modified acrylate pressure-sensitive adhesive are monomers, rubber, initiator, tackifying resin, and organic solvent.

[0048] The monomers are soft monomers, hard monomers and cross-linking monomers.

[0049] The soft monomer is butyl acrylate.

[0050] The hard monomer is methyl methacrylate.

[0051] The cross-linking monomer is hydroxyethyl acrylate.

[0052] The mass ratio of the soft monomer, the hard monomer and the cross-linking monomer is 22:1:2.

[0053] The rubber is natural rubber, butyl rubber and liquid isoprene rubber, and the mass ratio is 4:1:2.

[0054] The added amount of the rubber is 4% of the monomer mass.

[0055] The initiator dibenzoyl peroxide is added in an amount of 1% of the monomer mass.

[0056] The tackifying resins are water-based rosin tackifying emulsion and water-based terpene tackifying emulsion, with a mass ratio of 2:1.

[0057] The added amount of the tackifying resin is 5% of the monomer mass.

[0058] The organic solvent is ethyl acetate and methanol, with a mass ratio of 97:3.

[0059] The mass ratio of the organic solvent to the monomer is 6:5.

[0060] The preparation method of the low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive comprises the following steps: S1, dividing the organic solvent into organic solvent 1 and organic solvent 2, dissolving the rubber in organic solvent 1, adding the monomer, stirring and heating to 85° C., to obtain liquid 1; S2, adding the initiator into the organic solvent 2 and stirring evenly to prepare an initiator solution; S3. Keep the temperature of liquid 1 at 85°C, add the initiator solution dropwise into liquid 1, and complete the addition within 2.5 hours. Keep the temperature at 85°C for 1.5 hours, then cool to 40°C, add tackifying resin, continue stirring for 20 minutes, and filter to obtain.

[0061] The addition amount of the organic solvent 1 is 65% of the total mass of the organic solvent.

[0062] Example 2 The difference between this embodiment and embodiment 1 is that the monomers are soft monomers, hard monomers, and cross-linking monomers, and the mass ratio is 45:2:3.

[0063] Example 3 The difference between this embodiment and embodiment 1 is that the added amount of the rubber is 5% of the mass of the monomer.

[0064] Comparative Example 1 The difference between this comparative example and Example 1 is that the monomers are soft monomers, hard monomers, and cross-linking monomers, and the mass ratio is 22:2:1.

[0065] Comparative Example 2 The difference between this comparative example and Example 1 is that the monomers are soft monomers, hard monomers, and cross-linking monomers, and the mass ratio is 44:3:3.

[0066] Comparative Example 3 The difference between this comparative example and Example 1 is that the rubber is natural rubber.

[0067] Comparative Example 4 The difference between this comparative example and Example 1 is that the added amount of the rubber is 7% of the monomer mass.

[0068] Comparative Example 5 The difference between this comparative example and Example 1 is that the tackifying resin is an aqueous rosin tackifying emulsion.

[0069] Comparative Example 6 The difference between this comparative example and Example 1 is that the added amount of the tackifying resin is 2% of the weight of the monomer.

[0070] Comparative Example 7 The difference between this comparative example and Example 1 is that the organic solvent is ethyl acetate.

[0071] Comparative Example 8 The difference between this comparative example and Example 1 is that the organic solvent is ethyl acetate and methanol, and the mass ratio is 25:1.

[0072] Performance Testing The initial adhesion was tested according to GB 4852-2002, and the ball number was used to indicate the adhesion; the peeling force was tested according to GB / T 2792-1998; the lasting adhesion was tested according to GB / T 4851-1998, and the time when the ball fell was recorded; the viscosity was tested according to GB / T 2794-1995, and the test was performed using a rotational viscometer at a constant temperature of 25°C. The sample was prepared according to GB / T 2792-1998 and placed in a -15°C environment. After 24 hours, its peeling force was tested, and the peeling force loss rate was calculated as (initial peeling force - peeling force after 24 hours at low temperature) / initial peeling force × 100%. The results are shown in Table 1.

[0073] Table 1 Test results According to statistics, the low-temperature resistant rubber-modified acrylic pressure-sensitive adhesive prepared in Examples 1 to 3 of the present invention has good initial adhesion, high peeling force, excellent adhesive retention, high viscosity, good low-temperature resistance, and excellent peeling force at low temperatures. In Comparative Example 1, the hard monomer is excessive, in Comparative Example 2, the soft monomer is too little, in Comparative Example 3, there is only natural rubber, in Comparative Example 4, the rubber addition is too much, in Comparative Example 5, no water-based terpene thickening emulsion is added, in Comparative Example 6, the thickening resin addition is too low, in Comparative Example 7, no methanol is added, and in Comparative Example 8, the ethyl acetate addition is too high. The prepared low-temperature resistant rubber-modified acrylic pressure-sensitive adhesive has poor bonding performance and low-temperature resistance. Therefore, the water-based acrylic pressure-sensitive adhesive prepared by the raw materials and methods described in this application can not only improve the low-temperature resistance, but also improve the bonding strength.

[0074] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low temperature resistant rubber modified acrylate pressure sensitive adhesive, characterized in that: The raw materials for its preparation include monomers, rubber, initiator, tackifying resin and organic solvent; The rubber is one or more of natural rubber, isobutylene rubber, styrene-butadiene thermoplastic elastomer, styrene-isoprene thermoplastic elastomer, butyl rubber, nitrile rubber, and liquid isoprene rubber; The natural rubber has an initial plasticity of 42-46, a plasticity retention rate of 63%-67%, and an impurity content of ≤0.03%; the volatile matter of the butyl rubber is ≤0.5%, and at a test temperature of 125°C, the Mooney viscosity is 28-34, and the ash content is ≤0.7%; the liquid isoprene rubber has a molecular weight of 20,000-40,000, and a viscosity of 55-65 Pa·s at room temperature.

2. The low temperature resistant rubber modified acrylate pressure sensitive adhesive according to claim 1, characterized in that: The monomers include soft monomers, hard monomers, and cross-linking monomers.

3. The low temperature resistant rubber modified acrylate pressure sensitive adhesive according to claim 2, characterized in that: The mass ratio of the soft monomer, the hard monomer and the cross-linking monomer is (20-24):1:(1-3).

4. The low temperature resistant rubber modified acrylate pressure sensitive adhesive according to claim 1, characterized in that: The tackifying resin is one or more of water-based rosin tackifying emulsion and water-based terpene tackifying emulsion.

5. The low temperature resistant rubber modified acrylate pressure sensitive adhesive according to claim 4, characterized in that: The aqueous rosin tackifying emulsion has a viscosity of 100-400 mPa·s at room temperature, a solid content of 55±2%, and a pH value of 6-8.

6. The low temperature resistant rubber modified acrylate pressure sensitive adhesive according to claim 4, characterized in that: The aqueous terpene thickening emulsion has a viscosity of 600-800 mPa·s at room temperature, a solid content of 60±2%, and a pH value of 6-8.

7. The low temperature resistant rubber modified acrylate pressure sensitive adhesive according to claim 6, characterized in that: The added amount of the tackifying resin is 4% to 6% of the monomer mass.

8. The low temperature resistant rubber modified acrylate pressure sensitive adhesive according to claim 6, characterized in that: The organic solvent includes one or both of ethyl acetate and methanol.

9. A method for preparing the low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Separate the organic solvent into organic solvent 1 and organic solvent 2, dissolve the rubber in organic solvent 1, add the monomer, stir and heat to 80-90° C., and obtain liquid 1; S2, adding the initiator into the organic solvent 2 and stirring evenly to prepare an initiator solution; S3. Keep the temperature of liquid 1 at 80-90°C, add the initiator solution dropwise into liquid 1 within 2-3 hours, keep it at 80-90°C for 1-2 hours, then cool it to 30-50°C, add the tackifying resin, continue stirring for 15-30 minutes, and filter it.

10. Use of the low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive according to any one of claims 1 to 8 in the field of adhesives.

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