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

Abstract

This invention belongs to the field of adhesive technology, specifically relating to a low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive, its preparation method, and its application. The raw materials for preparing the low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive include monomers, rubber, initiators, tackifying resins, and organic solvents. The low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive provided by this invention, by introducing rubber as a raw material and through rational formulation design, combines rubber with acrylate pressure-sensitive adhesive, thereby improving both low-temperature resistance and adhesive strength, while simultaneously reducing production costs and meeting market demands.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, specifically relating to a low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive, its preparation method, and its application. Background Technology

[0002] In the adhesives industry, acrylic pressure-sensitive adhesives are widely favored for their excellent adhesion, transparency, and processability. 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 demands.

[0003] To improve the low-temperature resistance of acrylic pressure-sensitive adhesives, the industry typically modifies them by introducing special monomers. While these special monomers, such as fluorinated monomers and siloxane monomers, can improve the low-temperature resistance of pressure-sensitive adhesives to some extent, their complex manufacturing processes and high raw material costs result in expensive products, limiting their widespread 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 acrylate pressure-sensitive adhesives while improving their adhesive properties. Summary of the Invention

[0005] The purpose of this invention is to provide a low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive, its preparation method, and its application. By introducing rubber as a raw material and designing a reasonable formula, the rubber is combined with the acrylate pressure-sensitive adhesive, which can improve the low-temperature resistance and the bonding strength of the pressure-sensitive adhesive, while reducing production costs and meeting market demands.

[0006] A low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive, the raw materials for which are prepared include monomers, rubber, initiators, tackifying resins, and organic solvents.

[0007] Preferably, the monomers include soft monomers, hard monomers, and crosslinking monomers.

[0008] Preferably, the soft monomer includes one or more of butyl acrylate, n-octyl acrylate, and isooctyl acrylate; more 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 crosslinking 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, hard monomer, and crosslinking monomer is (20~24):1:(1~3); more preferably, it is 22:1:2.

[0012] The inventors discovered that by selecting specific soft monomers, hard monomers, and crosslinking monomers, and adjusting the proportions of their components, it is possible to improve the adhesive performance of pressure-sensitive adhesives (PSAs) while simultaneously enhancing their low-temperature resistance. This is due to the synergistic effect among these monomers. The flexibility and wettability of butyl acrylate (Bacrylate) help the PSA better contact the surface of the adhered object and form a strong bond, while the strength and hardness of methyl methacrylate (Mmethacrylate) ensure the stability and durability of the bonded joint. This synergistic effect allows the PSA to maintain flexibility while possessing sufficient strength to withstand various stress conditions. Hydroxyethyl acrylate (HYE) forms crosslinking points between the PSA molecular chains through its functional groups. These crosslinking points restrict the movement of the molecular chains at low temperatures, thus preventing the PSA from becoming brittle or losing its adhesive properties due to temperature drops. Simultaneously, the flexibility of Bacrylate helps alleviate the rigidity introduced by the crosslinking structure, allowing the PSA to maintain good flexibility and processability while retaining its low-temperature resistance. The rational proportions and interactions of these three monomers in the formulation result in excellent performance in both adhesive properties and low-temperature resistance of the PSA.

[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; more preferably, it is natural rubber, butyl rubber, or 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 content ≤0.5%, a Mooney viscosity of 28~34 at a test temperature of 125℃ (tested for 8 minutes after preheating with a large rotor for 1 minute), and an ash content ≤0.7%.

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

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

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

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

[0021] The inventors discovered that by selecting specific natural rubber, butyl rubber, and liquid isoprene rubber as raw materials, the adhesive properties and low-temperature resistance of pressure-sensitive adhesives (PSAs) can be further improved, and the viscosity of the PSAs can also be adjusted. This is likely because natural rubber provides good flexibility and initial tack, butyl rubber enhances the cohesive strength and aging resistance of the adhesive, and liquid isoprene rubber further improves the flexibility and flowability of the adhesive. By adjusting the ratio of natural rubber, butyl rubber, and liquid isoprene rubber, the three components can have a synergistic effect, achieving a balance between flexibility and flowability while further enhancing the cohesive strength and durability of the PSAs. This allows the PSAs to maintain good adhesion and cohesive strength even at low temperatures, improving its overall performance. Furthermore, the high flowability of liquid isoprene rubber helps to adjust the viscosity of the PSAs, making it more suitable for different coating processes. The addition of natural rubber and butyl rubber allows the PSAs to maintain high adhesion and cohesive strength while possessing better flowability and coating performance. The combination of these three factors makes the PSAs more flexible and easier to handle in practical applications.

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

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

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

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

[0026] Preferably, the viscosity of the aqueous rosin thickening emulsion at room temperature is 100~400 mPa·s, the solid content is 55±2%, and the pH value is 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 thickening emulsion and the aqueous terpene thickening emulsion are both purchased from Shenzhen Yoshida Chemical Co., Ltd., models 958 and 968.

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

[0030] The inventors discovered that by selecting specific water-based rosin tackifying emulsions and water-based terpene tackifying emulsions as tackifying resins, the adhesion effect of pressure-sensitive adhesives can be further improved, while also adjusting their solid content and viscosity. This is because the two water-based tackifying emulsions exhibit a significant synergistic effect. The active functional groups in rosin and terpene molecules can interact to form a more complex and stable cross-linked network structure. This structure not only enhances the cohesiveness and adhesion of the pressure-sensitive adhesive but also significantly improves its weather resistance. Simultaneously, the synergistic effect of the two tackifying emulsions can effectively adjust the viscosity and solid content of the pressure-sensitive adhesive, enabling the final product to meet the needs of different applications. Furthermore, this synergistic effect can optimize the wettability and permeability of the pressure-sensitive adhesive, making it easier to form a good adhesive interface with the surface of the adherend, thereby further improving the adhesion effect.

[0031] Preferably, the organic solvent includes one or both of ethyl acetate and methanol; more preferably, it is 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 discovered that by selecting a specific ratio of ethyl acetate and methanol as organic solvents, the low-temperature resistance of pressure-sensitive adhesives (PSAs) can be improved, and their viscosity and solid content can be adjusted. This is likely because, on the one hand, methanol, due to its low boiling point and high polarity, helps maintain the fluidity of the PSA at low temperatures, preventing hardening or embrittlement caused by temperature drops. On the other hand, ethyl acetate, through its excellent organic solubilizing effect, ensures the uniform distribution of the components in the PSA at low temperatures, avoiding performance degradation due to component separation. The synergistic effect of these two solvents significantly improves the low-temperature resistance of the PSA, allowing it to maintain good adhesion even in extreme low-temperature environments. On the other hand, the ratio of ethyl acetate to methanol directly affects the viscosity of the PSA. The addition of methanol reduces the viscosity of the system, making the PSA easier to coat and process. Ethyl acetate, however, increases the cohesive force of the system, increasing the viscosity of the PSA. By precisely adjusting the ratio of the two solvents, precise control of the PSA viscosity can be achieved. In addition, the synergistic blending of ethyl acetate and methanol not only helps control the evaporation rate of organic solvents in pressure-sensitive adhesives, but also affects the molecular arrangement and cross-linking degree 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 and adhesive properties.

[0035] The preparation method of the low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive includes the following steps:

[0036] S1. The organic solvent is divided into organic solvent one and organic solvent two. After dissolving the rubber in organic solvent one, the monomer is added, and the mixture is stirred and heated to 80~90℃ to obtain liquid one.

[0037] S2. Add the initiator to organic solvent II and stir until homogeneous to prepare an initiator solution;

[0038] S3. Keep the temperature of liquid one at 80~90℃, add the initiator solution dropwise to liquid one, and finish adding it within 2~3 hours. After keeping it at 80~90℃ for 1~2 hours, cool it down to 30~50℃, add the thickening resin, continue stirring for 15~30 minutes, and then filter to obtain the product.

[0039] Preferably, the amount of organic solvent one added is 60% to 70% of the total mass of organic solvent.

[0040] Application of the low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive in the field of adhesives.

[0041] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0042] 1. This invention provides a low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive. By introducing rubber as a raw material and designing a reasonable formula, the rubber is combined with the acrylate pressure-sensitive adhesive, which can improve the low-temperature resistance and the bonding strength of the pressure-sensitive adhesive, while reducing production costs and meeting market demands.

[0043] 2. By selecting specific soft monomers, hard monomers, and crosslinking monomers, and adjusting the proportion of each component, this invention can improve the low-temperature resistance of pressure-sensitive adhesives while enhancing their bonding performance.

[0044] 3. By selecting specific natural rubber, butyl rubber, and liquid isoprene rubber as raw materials, this invention can further improve the adhesion and low-temperature resistance of pressure-sensitive adhesives, and also adjust the viscosity of pressure-sensitive adhesives.

[0045] 4. This invention, by selecting specific water-based rosin tackifying emulsions and water-based terpene tackifying emulsions as tackifying resins, can further improve the bonding effect of pressure-sensitive adhesives, while also adjusting their solid content and viscosity. This is because the two water-based tackifying emulsions have a significant synergistic effect.

[0046] 5. By selecting ethyl acetate and methanol in specific proportions as organic solvents, this invention can improve the low-temperature resistance of pressure-sensitive adhesives and adjust their viscosity and solid content. Detailed Implementation

[0047] 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.

[0048] All raw materials used in this invention are commercially available, specifically:

[0049] Natural rubber, with an initial plasticity of 42-46, a plasticity retention rate of 63%-67%, and an impurity content of ≤0.03%; butyl rubber, with a volatile matter content of ≤0.5%, and a Mooney viscosity of 28-34 after 1 minute of preheating with a large rotor at a test temperature of 125℃ and a test time of 8 minutes, and an ash content of ≤0.7%; all were purchased from Shanghai Cunsi Industrial Co., Ltd.

[0050] Liquid isoprene rubber with a molecular weight of 30,000 and a viscosity of 60 Pa·s at room temperature; purchased from Shenzhen Masni Elastomer Co., Ltd.

[0051] The water-based rosin thickening 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; the water-based 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; both were purchased from Shenzhen Yoshida Chemical Co., Ltd., models 958 and 968.

[0052] Example 1

[0053] This embodiment provides a low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive, the raw materials for which are monomers, rubber, initiator, tackifying resin, and organic solvent.

[0054] The monomers are soft monomers, hard monomers, and cross-linked monomers.

[0055] The soft monomer is butyl acrylate.

[0056] The hard monomer is methyl methacrylate.

[0057] The crosslinking monomer is hydroxyethyl acrylate.

[0058] The mass ratio of the soft monomer, hard monomer, and crosslinking monomer is 22:1:2.

[0059] The rubber is natural rubber, butyl rubber, and liquid isoprene rubber in a mass ratio of 4:1:2.

[0060] The amount of rubber added is 4% of the monomer mass.

[0061] The initiator, benzoyl peroxide, is added at 1% of the monomer mass.

[0062] The tackifying resin is a water-based rosin tackifying emulsion and a water-based terpene tackifying emulsion, with a mass ratio of 2:1.

[0063] The amount of the tackifying resin added is 5% of the monomer mass.

[0064] The organic solvent is ethyl acetate and methanol in a mass ratio of 97:3.

[0065] The mass ratio of the organic solvent to the monomer is 6:5.

[0066] The preparation method of the low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive includes the following steps:

[0067] S1. The organic solvent is divided into organic solvent one and organic solvent two. After dissolving the rubber in organic solvent one, the monomer is added, and the mixture is stirred and heated to 85°C to obtain liquid one.

[0068] S2. Add the initiator to organic solvent II and stir until homogeneous to prepare an initiator solution;

[0069] S3. Keep the temperature of liquid one at 85℃, add the initiator solution dropwise to liquid one, and complete the addition within 2.5h. After keeping it at 85℃ for 1.5h, cool it down to 40℃, add the thickening resin, continue stirring for 20min, and then filter to obtain the product.

[0070] The amount of organic solvent one added is 65% of the total mass of the organic solvent.

[0071] Example 2

[0072] The difference between this embodiment and Embodiment 1 is that the monomers are soft monomers, hard monomers, and crosslinking monomers in a mass ratio of 45:2:3.

[0073] Example 3

[0074] The difference between this embodiment and Embodiment 1 is that the amount of rubber added is 5% of the monomer mass.

[0075] Comparative Example 1

[0076] The difference between this comparative example and Example 1 is that the monomers are soft monomers, hard monomers, and crosslinking monomers in a mass ratio of 22:2:1.

[0077] Comparative Example 2

[0078] The difference between this comparative example and Example 1 is that the monomers are soft monomers, hard monomers, and crosslinking monomers in a mass ratio of 44:3:3.

[0079] Comparative Example 3

[0080] The difference between this comparative example and Example 1 is that the rubber used is natural rubber.

[0081] Comparative Example 4

[0082] The difference between this comparative example and Example 1 is that the amount of rubber added is 7% of the monomer mass.

[0083] Comparative Example 5

[0084] The difference between this comparative example and Example 1 is that the tackifying resin is an aqueous rosin tackifying emulsion.

[0085] Comparative Example 6

[0086] The difference between this comparative example and Example 1 is that the amount of the tackifying resin added is 2% of the monomer mass.

[0087] Comparative Example 7

[0088] The difference between this comparative example and Example 1 is that the organic solvent used is ethyl acetate.

[0089] Comparative Example 8

[0090] The difference between this comparative example and Example 1 is that the organic solvent is ethyl acetate and methanol in a mass ratio of 25:1.

[0091] Performance testing

[0092] Initial tack was tested according to GB 4852-2002, with the ball number indicating the tack strength. Peel strength was tested according to GB / T 2792-1998. Holding strength was tested according to GB / T 4851-1998, and the time it took for the ball to fall was recorded. Viscosity was tested according to GB / T 2794-1995, using a rotational viscometer under constant temperature conditions of 25℃. Samples were prepared according to GB / T 2792-1998 and placed in an environment of -15℃. After 24 hours, the peel strength was tested, and the peel strength loss rate was calculated as (initial peel strength - peel strength after 24 hours at low temperature) / initial peel strength × 100%. The results are shown in Table 1.

[0093] Table 1 Test Results

[0094]

[0095] According to statistics, the low-temperature resistant rubber-modified acrylate pressure-sensitive adhesives prepared in Examples 1-3 of this invention have good initial tack, high peel strength, and excellent holding power. They also have high viscosity, good low-temperature resistance, and excellent peel strength even at low temperatures. Comparative Example 1 had excessive hard monomers, Comparative Example 2 had insufficient soft monomers, Comparative Example 3 contained only natural rubber, Comparative Example 4 had excessive rubber addition, Comparative Example 5 did not add waterborne terpene tackifying emulsion, Comparative Example 6 had insufficient tackifying resin addition, Comparative Example 7 did not add methanol, and Comparative Example 8 had excessive ethyl acetate addition. The resulting low-temperature resistant rubber-modified acrylate pressure-sensitive adhesives all exhibited poor bonding and low-temperature resistance. Therefore, the waterborne acrylate pressure-sensitive adhesive prepared using the raw materials and methods described in this application not only improves low-temperature resistance but also enhances bonding strength.

[0096] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-temperature resistant rubber-modified acrylic pressure-sensitive adhesive, characterized in that, Its raw materials include monomers, rubber, initiators, tackifying resins, and organic solvents; The monomer is composed of soft monomers, hard monomers, and crosslinking monomers in a mass ratio of (20~24):1:(1~3); The soft monomer is butyl acrylate, the hard monomer is methyl methacrylate, and the crosslinking monomer is hydroxyethyl acrylate; The rubber is a combination of natural rubber, butyl rubber, and liquid isoprene rubber in a mass ratio of 4:1:2; 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 butyl rubber has a volatile matter content of ≤0.5%, a Mooney viscosity of 28-34 at 125℃, and an ash content of ≤0.7%; the liquid isoprene rubber has a molecular weight of 20,000-40,000 and a viscosity at room temperature of 55-65 Pa·s; the amount of rubber added is 3%-5% of the monomer mass. The tackifying resin is one or more of water-based rosin tackifying emulsion and water-based terpene tackifying emulsion, and the amount of the tackifying resin added is 4% to 6% of the monomer mass; The organic solvent includes one or both of ethyl acetate and methanol; The initiator is one or both of azobisisobutyronitrile and benzoyl peroxide, and the amount added is 0.5% to 2% of the monomer mass.

2. The low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive according to claim 1, characterized in that, The soft monomer is butyl acrylate, the hard monomer is methyl methacrylate, and the crosslinking monomer is hydroxyethyl acrylate, with a mass ratio of 22:1:

2.

3. The low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive according to claim 1, characterized in that, The aqueous rosin thickening 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.

4. The low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive according to claim 1, 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.

5. The low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive according to claim 1, characterized in that, The mass ratio of ethyl acetate to methanol is 97:3, and the mass ratio of organic solvent to monomer is 6:

5.

6. The low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive according to claim 1, characterized in that, The initiator is benzoyl peroxide, and the amount added is 1% of the monomer mass.

7. The low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive according to claim 1, characterized in that, The tackifying resin is composed of an aqueous rosin tackifying emulsion and an aqueous terpene tackifying emulsion in a mass ratio of 2:

1.

8. A method for preparing a low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive according to any one of claims 1-7, characterized in that, Includes the following steps: S1. The organic solvent is divided into organic solvent one and organic solvent two. After dissolving the rubber in organic solvent one, the monomer is added, and the mixture is stirred and heated to 80~90℃ to obtain liquid one. S2. Add the initiator to organic solvent II and stir until homogeneous to prepare an initiator solution; S3. Keep the temperature of liquid one at 80~90℃, add the initiator solution dropwise to liquid one, and finish adding it within 2~3 hours. After keeping it at 80~90℃ for 1~2 hours, cool it down to 30~50℃, add the thickening resin, continue stirring for 15~30 minutes, and then filter to obtain the product.

9. The application of a low-temperature resistant rubber-modified acrylate pressure-sensitive adhesive according to any one of claims 1-7 in the field of adhesives.

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