Copolymer, preparation method thereof, pressure-sensitive adhesive and application of pressure-sensitive adhesive

Abstract

The invention provides a copolymer, a preparation method of the copolymer, a pressure-sensitive adhesive and application of the pressure-sensitive adhesive. Comonomers of the copolymer comprise (methyl) acrylic acid, (methyl) alkyl acrylate and other functional monomers, the mass ratio of the (methyl) acrylic acid to the (methyl) alkyl acrylate to the other functional monomers is 1: (20-35): (1.5-2), and the acid value of the copolymer is 10-15 mgKOH / g; the other functional monomers are selected from any one or more of olefin compounds, amide compounds and ester compounds. The (methyl) acrylic acid, the alkyl (methyl) acrylate and other functional monomers give full play to the synergistic effect of comonomers, so that the warping resistance and binding power of the pressure-sensitive adhesive are improved. Therefore, the pressure-sensitive adhesive prepared from the copolymer disclosed by the invention has relatively good warping resistance and binding power.

Description

Technical Field

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

[0002] The development of China's automotive assembly adhesive industry is closely linked to the overall development of the automotive industry. Continuous technological innovation and industrial chain synergy are the keys to its sustainable development. Automotive interior mainly refers to automotive products used for automotive interior modification, involving all aspects of the interior of the car. Because the car is in high and low temperatures and bumpy working environments during use, the automotive interior must be firmly adhered to the body itself. Because the body has a curvature, it cannot warp on the curved surface during the adhesion process. With the development of trends such as lightweight cars, new energy vehicles, and interior upgrades, there is a strong demand for high-quality, high-performance adhesives.

[0003] The development trend of automotive adhesives is mainly reflected in technological innovation to meet the needs of lightweight vehicles, while focusing on the development and application of environmentally friendly adhesives and the expansion of their application in the field of new energy vehicles. According to the survey, the most commonly used acrylic resin coating adhesive on the market has poor warping resistance, insufficient adhesion, and the solvent is mostly toluene, which is not conducive to environmental protection and VOC control inside the car. Summary of the invention

[0004] The main purpose of the present invention is to provide a copolymer and a preparation method thereof, a pressure-sensitive adhesive and an application thereof, so as to solve the problems of poor warping resistance and insufficient bonding strength of the pressure-sensitive adhesive in the prior art.

[0005] In order to achieve the above object, according to one aspect of the present invention, a copolymer is provided, wherein the copolymer monomers of the copolymer include: (meth)acrylic acid, (meth)acrylic acid alkyl ester and other functional monomers, the mass ratio of (meth)acrylic acid, (meth)acrylic acid alkyl ester and other functional monomers is 1:(20-35):(1.5-2), and the acid value of the copolymer is 10-15 mgKOH / g; the other functional monomers are selected from any one or more of olefin compounds, amide compounds and ester compounds.

[0006] Furthermore, the weight average molecular weight of the copolymer is 450,000 to 1,000,000, preferably 450,000 to 650,000.

[0007] Further, the (meth)acrylic acid is acrylic acid and / or methacrylic acid; and / or, the alkyl (meth)acrylate is selected from any one or more of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexyl methacrylate, heptyl acrylate, heptyl methacrylate, octyl acrylate, isooctyl acrylate, octyl methacrylate, nonyl acrylate, nonyl methacrylate, decyl acrylate, decyl methacrylate, lauryl acrylate and lauryl methacrylate; preferably, the alkyl (meth)acrylate contains at least butyl acrylate; preferably, the alkyl (meth)acrylate is a combination of butyl acrylate and isooctyl acrylate, and the mass ratio of butyl acrylate to isooctyl acrylate is 2 to 4:1; and / or, other functional monomers are selected from benzene Any one or more of ethylene, acrylamide, N-hydroxymethyl acrylamide, vinyl acetate, tetrahydrofuran acrylate, tetrahydrofuran methacrylate, isobornyl acrylate, isobornyl methacrylate, dimethylaminomethyl acrylate, dimethylaminomethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminomethyl acrylate, diethylaminomethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate and hydroxybutyl methacrylate; preferably, the other functional monomer is hydroxyethyl acrylate and / or vinyl acetate; preferably, the other functional monomer is a combination of hydroxyethyl acrylate and vinyl acetate, and the mass ratio of hydroxyethyl acrylate to vinyl acetate is 1:20-60.

[0008] Further, the raw materials of the above-mentioned copolymer include an initiator, and the mass of the initiator is 0.5-1% of the mass of the monomer; and / or, the raw materials of the copolymer include a solvent, and the mass of the solvent is 110-120% of the mass of the monomer; preferably, the initiator is selected from any one or more of azobisisobutyronitrile, azobisisoheptanenitrile, azobisisovaleronitrile, dibenzoyl peroxide and 1,4-(di-tert-butylpercarbonyl)cyclohexane; and / or, the solvent is selected from any one or more of ethyl acetate, butyl acetate, toluene, xylene and N,N-dimethylformamide; further preferably, the raw materials of the copolymer include an initiator and a solvent, the initiator is selected from any one or more of azobisisobutyronitrile, azobisisoheptanenitrile and azobisisovaleronitrile, and the solvent is selected from any one or more of ethyl acetate, butyl acetate and N,N-dimethylformamide.

[0009] According to another aspect of the present invention, a method for preparing the aforementioned copolymer is provided, the method comprising: placing raw materials including a comonomer, a solvent and an initiator in a reactor to carry out a polymerization reaction to obtain a copolymer.

[0010] Furthermore, the polymerization reaction temperature is 65-70° C.; and / or the polymerization reaction time is 5-10 h.

[0011] Furthermore, the above-mentioned comonomer, solvent and initiator are added in batches; preferably, the preparation method comprises: step S1, by mass fraction, adding 40-50% of the comonomer and 65-90% of the solvent as a base material into a reactor; step S2, adding 40-50% of the comonomer and 0.8-7% of the solvent as a drop material; step S3, when the reactor is heated to 65-70°C, adding 15-25% of the initiator into the reactor and keeping the temperature for 1-1.5h; then, The drop material is added dropwise to the reactor, and 10-40% of the initiator is added to the reactor during the drop material addition. The drop material addition time is 1.5-3h. After the drop addition is completed, keep warm for 0.5-2h. 4-5% of the monomer and 20-30% of the initiator are added to the reactor and kept warm for 1-2h. The remaining comonomer, 0-3% of the solvent and the remaining initiator are added to the reactor and kept warm for 1-1.5h. The remaining solvent is added to the reactor and the polymerization reaction is terminated to obtain a copolymer.

[0012] Furthermore, during the above-mentioned dripping of the feed, 10-40% of the initiator is divided into 3-4 portions and added into the reaction kettle.

[0013] According to another aspect of the present invention, a pressure-sensitive adhesive is provided. The pressure-sensitive adhesive comprises the following raw materials in parts by weight: 70 to 95 parts of the aforementioned copolymer, 5 to 30 parts of rosin resin and 0 to 5 parts of a curing agent.

[0014] According to another aspect of the present invention, there is provided a use of the aforementioned pressure-sensitive adhesive in bonding automobile interior trims.

[0015] By applying the technical solution of the present application, (meth)acrylic acid as a polar monomer can increase the polarity of the copolymer, thereby helping to improve the adhesion of the adhesive to different substrates. The introduction of alkyl (meth)acrylate helps to provide good cohesion and heat resistance. The introduction of other functional monomers helps to further improve the cohesion, solvent resistance and temperature resistance of the pressure-sensitive adhesive. Controlling the mass ratio of (meth)acrylic acid, alkyl (meth)acrylate and other functional monomers within the above range helps to give full play to the synergistic effect of each copolymerized monomer, thereby helping to further improve the warping resistance and adhesion of the pressure-sensitive adhesive. Too high or too low an acid value may affect the stability, viscosity and compatibility of the adhesive with the substrate. Controlling the acid value of the copolymer within the above range helps to improve the adhesion of the adhesive. DETAILED DESCRIPTION

[0016] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0017] As analyzed in the background technology of this application, the pressure-sensitive adhesives in the prior art have the problems of poor warping resistance and insufficient bonding strength. In order to solve this problem, this application provides a copolymer and a preparation method thereof, a pressure-sensitive adhesive and applications thereof.

[0018] In a typical embodiment of the present application, a copolymer is provided, wherein the copolymer monomers of the copolymer include: (meth)acrylic acid, (meth)acrylic acid alkyl ester and other functional monomers, the mass ratio of (meth)acrylic acid, (meth)acrylic acid alkyl ester and other functional monomers is 1:(20-35):(1.5-2), specifically 1:22.45:1.55, 1:26.40:1.17, 1:25.83:1.74, 1:33.21:1.50 and a range value between any two ratios, and the acid value of the copolymer is 10-15 mgKOH / g; the other functional monomers are selected from any one or more of olefin compounds, amide compounds and ester compounds.

[0019] As a polar monomer, (meth)acrylic acid can increase the polarity of the copolymer, thereby helping to improve the adhesion of the adhesive to different substrates. The introduction of alkyl (meth)acrylates helps to provide good cohesion and heat resistance. The introduction of other functional monomers helps to further improve the cohesion, solvent resistance and temperature resistance of the pressure-sensitive adhesive. Controlling the mass ratio of (meth)acrylic acid, alkyl (meth)acrylates and other functional monomers within the above range helps to give full play to the synergistic effect of each copolymer, thereby helping to further improve the warping resistance and adhesion of the pressure-sensitive adhesive. Too high or too low an acid value may affect the stability, viscosity and compatibility of the adhesive with the substrate. Controlling the acid value of the copolymer within the above range helps to improve the adhesion of the adhesive.

[0020] In one embodiment of the present application, the weight average molecular weight of the copolymer is 450,000-1,000,000; preferably 450,000-650,000, specifically 450,000, 500,000, 550,000, 600,000, 650,000 and a range between any two values.

[0021] If the weight average molecular weight of the copolymer is too small, the cohesion of the adhesive layer is insufficient, which may lead to a decrease in the adhesiveness. If the weight average molecular weight of the copolymer is too high, the viscosity of the pressure-sensitive adhesive is too high, which is not conducive to coating. Controlling the weight average molecular weight of the copolymer within the above range helps the adhesive maintain good adhesion and stability on the curved surface.

[0022] In one embodiment of the present application, the (meth)acrylic acid is acrylic acid and / or methacrylic acid; and / or, the alkyl (meth)acrylate is selected from any one or more of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexyl methacrylate, heptyl acrylate, heptyl methacrylate, octyl acrylate, isooctyl acrylate, octyl methacrylate, nonyl acrylate, nonyl methacrylate, decyl acrylate, decyl methacrylate, lauryl acrylate and lauryl methacrylate; preferably, the alkyl (meth)acrylate contains at least butyl acrylate; preferably, the alkyl (meth)acrylate is a combination of butyl acrylate and isooctyl acrylate, and the mass ratio of butyl acrylate to isooctyl acrylate is 2 to 4:1; and / or, other functional monomers The monomer is selected from any one or more of styrene, acrylamide, N-hydroxymethyl acrylamide, vinyl acetate, tetrahydrofuran acrylate, tetrahydrofuran methacrylate, isobornyl acrylate, isobornyl methacrylate, dimethylaminomethyl acrylate, dimethylaminomethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminomethyl acrylate, diethylaminomethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate and hydroxybutyl methacrylate; preferably, the other functional monomer is hydroxyethyl acrylate and / or vinyl acetate; preferably, the other functional monomer is a combination of hydroxyethyl acrylate and vinyl acetate, and the mass ratio of hydroxyethyl acrylate to vinyl acetate is 1:20-60.

[0023] Controlling the type of alkyl (meth)acrylate within the above range helps to control the length of the alkyl chain in the alkyl (meth)acrylate within a suitable range, thereby helping to improve the flexibility and temperature resistance of the adhesive and reduce warping. Controlling the mass ratio of butyl acrylate and isooctyl acrylate within the above range helps to improve the synergistic effect between the two, so that the coating formed by the pressure-sensitive adhesive has good flexibility and hardness, thereby maintaining good adhesion under a variety of environmental conditions. Controlling the types of other functional monomers within the above range, especially hydroxyethyl acrylate and vinyl acetate, their introduction helps to further improve the cohesion, solvent resistance and temperature resistance of the adhesive. Controlling the mass ratio of hydroxyethyl acrylate and vinyl acetate within the above range helps to further improve the adhesion and anti-warping properties of the adhesive.

[0024] In one embodiment of the present application, the raw materials of the above-mentioned copolymer include an initiator, and the mass of the initiator is 0.5-1% of the mass of the monomer; and / or, the raw materials of the copolymer include a solvent, and the mass of the solvent is 110-120% of the mass of the monomer; preferably, the initiator is selected from any one or more of azobisisobutyronitrile, azobisisoheptanenitrile, azobisisovaleronitrile, dibenzoyl peroxide and 1,4-(di-tert-butylpercarbonyl)cyclohexane; and / or, the solvent is selected from any one or more of ethyl acetate, butyl acetate, toluene, xylene and N,N-dimethylformamide; further preferably, the raw materials of the copolymer include an initiator and a solvent, the initiator is selected from any one or more of azobisisobutyronitrile, azobisisoheptanenitrile and azobisisovaleronitrile, and the solvent is selected from any one or more of ethyl acetate, butyl acetate and N,N-dimethylformamide.

[0025] Controlling the mass proportion of the initiator within the above range can help improve the efficiency of the polymerization reaction and reduce side reactions caused by excessive initiator or too wide molecular weight distribution of the polymer. Controlling the type of initiator within the above range can help provide appropriate reaction activity, promote polymerization under mild conditions, reduce energy consumption, and improve production safety. Controlling the mass proportion of the solvent within the above range can help improve the solubility of the monomer, control the molecular weight of the polymer within an appropriate range, and reduce the reduction in viscosity of the adhesive caused by excessive solvent. Controlling the type of solvent within the above range can help further improve the solubility of the comonomer in the solvent, reduce the VOC content, and improve environmental protection.

[0026] In another typical embodiment of the present application, a method for preparing the aforementioned copolymer is provided, the method comprising: placing raw materials including a comonomer, a solvent and an initiator in a reactor to carry out a polymerization reaction to obtain a copolymer.

[0027] The copolymer preparation method of the present application is simple, low-cost and suitable for large-scale production.

[0028] In one embodiment of the present application, the polymerization reaction temperature is 65-70° C.; and / or the polymerization reaction time is 5-10 h.

[0029] A lower reaction temperature is conducive to controlling the polymerization rate and reducing the occurrence of chain termination reactions, thereby helping to form a polymer with a higher molecular weight. Controlling the polymerization temperature within the above range helps to form a copolymer with a suitable weight average molecular weight, thereby helping to improve the cohesion and adhesion of the pressure-sensitive adhesive. Controlling the polymerization time within the above range helps to improve the efficiency of the polymerization reaction.

[0030] In one embodiment of the present application, the above-mentioned comonomer, solvent and initiator are added in batches; preferably, the preparation method comprises: step S1, by mass fraction, adding 40-50% of the comonomer and 65-90% of the solvent as a base material to the reactor; step S2, adding 40-50% of the comonomer and 0.8-7% of the solvent as a drop material; step S3, when the reactor is heated to 65-70°C, 15-25% of the initiator is added to the reactor, and the temperature is kept for 1-1.5 hours; Then, the drop material is added dropwise to the reactor, and 10-40% of the initiator is added to the reactor during the drop material addition. The drop material addition time is 1.5-3 hours. After the drop addition is completed, it is kept warm for 0.5-2 hours. 4-5% of the monomer and 20-30% of the initiator are added to the reactor and kept warm for 1-2 hours. The remaining comonomer, 0-3% of the solvent and the remaining initiator are added to the reactor and kept warm for 1-1.5 hours. After the remaining solvent is added to the reactor, the polymerization reaction is terminated to obtain a copolymer.

[0031] Adding comonomers in batches helps to more finely control the polymerization process and form copolymers with moderate molecular weight and uniform distribution, which helps to improve the adhesion, cohesion and anti-warping properties of the adhesive.

[0032] It should be noted that the mass percentage of the above comonomers refers to the mass percentage of the total comonomers; the mass percentage of the solvent refers to the mass percentage of the total solvents; and the mass percentage of the initiator refers to the mass percentage of the total initiators.

[0033] In one embodiment of the present application, 40-50% of comonomer and 65-90% of solvent are added into a reaction kettle as a base material, stirred and nitrogen substituted for 5-30 minutes.

[0034] In one embodiment of the present application, during the dripping of the feed, 10-40% of the initiator is divided into 3-4 portions and added into the reaction kettle.

[0035] Adding the initiator multiple times can help further control the rate of the polymerization reaction, keep it relatively stable throughout the entire dropping process, help form a polymer with a narrower molecular weight distribution, and help improve the performance consistency of the adhesive.

[0036] In another typical embodiment of the present application, a pressure-sensitive adhesive is provided, which comprises the following raw materials in parts by weight: 70 to 95 parts of the aforementioned copolymer, 5 to 30 parts of rosin resin and 0 to 5 parts of a curing agent; preferably, the pressure-sensitive adhesive comprises the following raw materials in parts by weight: 79 to 94 parts of the aforementioned copolymer, 5 to 21 parts of rosin resin and 0.5 to 1 part of a curing agent.

[0037] Since the pressure-sensitive adhesive contains the copolymer of the present application, the pressure-sensitive adhesive has high warping resistance and adhesion.

[0038] Including but not limited to, the above-mentioned rosin resin is selected from any one or more of masson pine glyceride, elliottia pine glyceride, masson pine pentaerythritol ester, elliottia pine pentaerythritol ester, rosin terpene phenol resin, hydrogenated rosin resin, maleic acid rosin glyceride, maleic acid rosin pentaerythritol ester and special rosin resin.

[0039] Including but not limited to, the curing agent is selected from any one or more of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and lysine diisocyanate.

[0040] In another typical embodiment of the present application, a method for preparing a pressure-sensitive adhesive is provided, wherein raw materials including a copolymer, a rosin resin and a curing agent are mixed and dispersed to obtain a pressure-sensitive adhesive.

[0041] In another typical embodiment of the present application, there is provided application of the aforementioned pressure-sensitive adhesive in bonding automobile interiors.

[0042] The pressure-sensitive adhesive of the present application has high warping resistance and bonding strength, and may be toluene-free, and can be used for bonding automobile interiors.

[0043] The beneficial effects of the present application will be further illustrated below in conjunction with embodiments.

[0044] Preparation Example 1

[0045] In terms of weight, the raw materials of the copolymer are: 100 parts of comonomer, 1 part of initiator, and 120 parts of solvent. The comonomer is: acrylic acid / butyl acrylate / isooctyl acrylate / hydroxyethyl acrylate / vinyl acetate = 4 / 70.8 / 19 / 0.2 / 6 (weight ratio); the initiator is azobisisobutyronitrile, which is 1.0wt% of the total monomer amount; the solvent is ethyl acetate, which is 120wt% of the total monomer amount.

[0046] Copolymer A-1 was prepared as follows:

[0047] a) washing kettle;

[0048] b) adding 47 parts by weight of a comonomer (a mixture of acrylic acid, butyl acrylate, isooctyl acrylate and hydroxyethyl acrylate) and 108 parts by weight of a solvent as a base material into a reaction kettle, stirring and mixing, and nitrogen replacement for 30 minutes;

[0049] c) in a monomer dropping tank, 47 parts by weight of a comonomer (a mixture of acrylic acid, butyl acrylate, isooctyl acrylate and hydroxyethyl acrylate) and 2.4 parts by weight of a solvent are stirred uniformly as a dropping material;

[0050] d) After nitrogen replacement is completed, the reaction kettle is heated, and when the temperature rises to 70° C., 0.15 parts by weight of initiator is added, and the reaction is kept at this temperature for 1.0 h;

[0051] e) After the heat preservation is completed, the dropwise addition material in c) is added dropwise to the reactor over 1.5 hours. During the dropwise addition, 0.4 parts by weight of the initiator is added in four parts. After the dropwise addition is completed, the temperature is kept for 0.5 hours;

[0052] f) after the heat preservation is completed, 4.2 parts by weight of the comonomer (vinyl acetate) and 0.20 parts by weight of the initiator are added to the reactor, and the heat preservation is continued for 1 hour;

[0053] g) after the heat preservation is completed, 1.8 parts by weight of the comonomer (vinyl acetate) and 0.25 parts by weight of the initiator are added to the reactor, and the reaction mixture is kept warm for 1 hour;

[0054] h) After the insulation is completed, 9.6 parts by weight of solvent is added to the reaction kettle as a diluent, and the temperature is lowered and the material is discharged.

[0055] The weight average molecular weight and acid value of the prepared copolymer were tested, and the weight average molecular weight was 490,000 (weight average molecular weight data acquisition conditions: Shimadzu LC-20A liquid chromatography, polymethyl methacrylate as a standard for working curve, the following weight average molecular weight data are the same conditions), and the acid value was 14.1 mgKOH / g.

[0056] Preparation Example 2

[0057] The difference from Preparation Example 1 is that, in terms of weight, the raw materials of the copolymer are: 100 parts of comonomer, 0.5 parts of initiator, and 115 parts of solvent. The comonomer is: acrylic acid / butyl acrylate / hydroxyethyl acrylate / vinyl acetate = 3.5 / 92.4 / 0.1 / 4 (weight ratio); the initiator is azobisisobutyronitrile, which is 0.5wt% of the total monomer amount; the solvent is ethyl acetate and toluene, ethyl acetate is 100wt% of the total monomer amount, and toluene is 15wt% of the total monomer amount.

[0058] Copolymer A-2 was prepared as follows:

[0059] a) washing kettle;

[0060] b) adding 48 parts by weight of comonomer (a mixture of acrylic acid, butyl acrylate and hydroxyethyl acrylate) and 11 parts by weight of toluene and 65 parts by weight of ethyl acetate as a base material into a reaction kettle, stirring and mixing, and nitrogen replacement for 30 minutes;

[0061] c) in a monomer dropping tank, 48 parts by weight of a comonomer (a mixture of acrylic acid, butyl acrylate and hydroxyethyl acrylate) and 1 part by weight of toluene are stirred uniformly as a dropping material;

[0062] d) After nitrogen replacement is completed, the reaction kettle is heated, and when the temperature rises to 65° C., 0.1 parts by weight of initiator is added, and the reaction is kept at this temperature for 1 hour;

[0063] e) After the heat preservation is completed, the dropwise addition material in c) is added dropwise to the reactor over 1.5 hours. During the dropwise addition, 0.05 parts by weight of the initiator is added in three portions. After the heat preservation is completed, the reaction is continued for 0.5 hours;

[0064] f) after the heat preservation is completed, 4 parts by weight of the comonomer (vinyl acetate) and 0.15 parts by weight of the initiator are added to the reactor, and the heat preservation is continued for 1 hour;

[0065] g) after the heat preservation is completed, 3 parts by weight of toluene and 0.2 parts by weight of initiator are added to the reactor, and the heat preservation is completed for 1 hour;

[0066] h) After the insulation is completed, 35 parts by weight of ethyl acetate is added to the reactor as a diluent, and the temperature is lowered and the material is discharged.

[0067] The weight average molecular weight and acid value of the prepared copolymer were tested. The weight average molecular weight was 600000, and the acid value was 12.1 mgKOH / g.

[0068] Preparation Example 3

[0069] The difference from Preparation Example 1 is that, in terms of weight, the raw materials of the copolymer are: 100 parts of comonomer, 0.6 parts of initiator, and 115 parts of solvent. The comonomer is: acrylic acid / butyl acrylate / hydroxyethyl acrylate / vinyl acetate = 3.5 / 92.4 / 0.1 / 4 (weight ratio); the initiator is azobisisobutyronitrile, which is 0.6wt% of the total monomer amount; and the solvent is ethyl acetate, which is 115wt% of the total monomer amount.

[0070] Copolymer A-3 was prepared as follows:

[0071] a) washing kettle;

[0072] b) adding 48 parts by weight of comonomer (a mixture of acrylic acid, butyl acrylate and hydroxyethyl acrylate) and 75 parts by weight of ethyl acetate as a base material into a reaction kettle, stirring and mixing, and nitrogen replacement for 30 minutes;

[0073] c) in a monomer dropping tank, 48 parts by weight of a comonomer (a mixture of acrylic acid, butyl acrylate and hydroxyethyl acrylate), 0.15 parts by weight of an initiator and 7.5 parts by weight of ethyl acetate are stirred uniformly as a dropping material;

[0074] d) After nitrogen replacement is completed, the reaction kettle is heated, and when the temperature rises to 65° C., 0.1 parts by weight of initiator is added, and the reaction is kept at this temperature for 1 hour;

[0075] e) After the insulation is completed, the material added in c) is added dropwise to the reactor over 1.5 hours, and then the temperature is kept for 0.5 hours;

[0076] f) after the heat preservation is completed, 4 parts by weight of the comonomer (vinyl acetate) and 0.15 parts by weight of the initiator are added to the reactor, and the heat preservation is continued for 1 hour;

[0077] g) after the heat preservation is completed, 3 parts by weight of ethyl acetate and 0.2 parts by weight of initiator are added to the reaction kettle, and the heat preservation is completed for 1.5 hours;

[0078] h) After the insulation is completed, 29.5 parts by weight of ethyl acetate is added to the reaction kettle as a diluent, and the temperature is lowered and the material is discharged.

[0079] The weight average molecular weight and acid value of the prepared copolymer were tested. The weight average molecular weight was 600000, and the acid value was 12.1 mgKOH / g.

[0080] Preparation Example 4

[0081] The only difference from Preparation Example 1 is that the copolymer monomers are: acrylic acid / butyl acrylate / hydroxyethyl acrylate / vinyl acetate=3.5 / 90.4 / 0.1 / 6 (weight ratio).

[0082] The copolymer A-4 was prepared, and its weight average molecular weight was 490,000 and its acid value was 12.5 mgKOH / g.

[0083] Preparation Example 5

[0084] The only difference from Preparation Example 2 is that the comonomers are: acrylic acid / butyl acrylate / hydroxyethyl acrylate / vinyl acetate = 2.8 / 93 / 0.2 / 4 (weight ratio).

[0085] The prepared copolymer A-5 had a weight average molecular weight of 550,000 and an acid value of 10 mgKOH / g.

[0086] Preparation Example 6

[0087] The raw materials for preparing the copolymer are the same as those in Preparation Example 1, except that in step e) of the preparation method, the initiator is mixed evenly with the dropwise addition material prepared in step c) and then dropwise added to the reactor.

[0088] The copolymer A-6 was prepared, and had a weight average molecular weight of 500,000 and an acid value of 14.1 mgKOH / g.

[0089] Preparation Example 7

[0090] The difference from Preparation Example 1 is that the copolymer monomers are: acrylic acid / butyl acrylate / isooctyl acrylate / hydroxyethyl acrylate / vinyl acetate = 4 / 70.8 / 19 / 0.2 / 10 (weight ratio), and copolymer A-7 is prepared, which has a weight average molecular weight of 900000 and an acid value of 13.6 mgKOH / g.

[0091] Preparation Example 8

[0092] The difference from Preparation Example 1 is that the total amount of butyl acrylate and isooctyl acrylate remains unchanged, and the mass ratio of butyl acrylate to isooctyl acrylate is 2:1. Copolymer A-8 is prepared, and its weight average molecular weight is 550,000 and acid value is 14.1 mgKOH / g.

[0093] Preparation Example 9

[0094] The difference from Preparation Example 1 is that the total amount of butyl acrylate and isooctyl acrylate remains unchanged, and the mass ratio of butyl acrylate to isooctyl acrylate is 4:1. Copolymer A-9 is prepared, and its weight average molecular weight is 500,000 and acid value is 14.1 mgKOH / g.

[0095] Preparation Example 10

[0096] The difference from Preparation Example 1 is that the total amount of butyl acrylate and isooctyl acrylate remains unchanged, and the mass ratio of butyl acrylate to isooctyl acrylate is 1:1. Copolymer A-10 is prepared, and its weight average molecular weight is 800,000 and acid value is 14.1 mgKOH / g.

[0097] Preparation Example 11

[0098] The difference from Preparation Example 1 is that the total amount of hydroxyethyl acrylate and vinyl acetate remains unchanged, and the mass ratio of hydroxyethyl acrylate to vinyl acetate is 1:15, and copolymer A-11 is prepared, which has a weight average molecular weight of 400,000 and an acid value of 14.1 mgKOH / g.

[0099] Preparation Example 12

[0100] The difference from Preparation Example 1 is that the copolymer monomers are: methacrylic acid / isopropyl methacrylate / decyl methacrylate / styrene / diethylaminoethyl acrylate = 4 / 70.8 / 19 / 0.2 / 6 (weight ratio); copolymer A-12 is prepared, and its weight average molecular weight is 500000 and acid value is 11.8 mgKOH / g.

[0101] Preparation Example 13

[0102] The difference from Preparation Example 1 is that the copolymer monomers are: acrylic acid / butyl acrylate / isooctyl acrylate / hydroxyethyl acrylate / vinyl acetate = 4 / 23.6 / 6.3 / 0.1 / 3 (weight ratio); copolymer A-13 is prepared, and its weight average molecular weight is 100000 and acid value is 38 mgKOH / g.

[0103] Preparation Example 14

[0104] The difference from Preparation Example 1 is that the copolymer monomers are: acrylic acid / butyl acrylate / isooctyl acrylate / hydroxyethyl acrylate / vinyl acetate = 4 / 141.6 / 38 / 0.4 / 12 (weight ratio); copolymer A-14 is prepared, and its weight average molecular weight is 170000 and acid value is 7.3 mgKOH / g.

[0105] Examples 1 to 15

[0106] The specific formula components of the adhesives of Examples 1 to 8 are shown in Table 1, and the specific formula components of the adhesives of Examples 9 to 15 are shown in Table 2, in parts by weight.

[0107] Table 1

[0108]

[0109]

[0110] Table 2

[0111]

[0112] Comparative Examples 1 to 4

[0113] The specific formula components of the adhesive are shown in Table 3 in parts by weight.

[0114] Table 3

[0115]

[0116] The specific composition of each material in Tables 1 to 3 is as follows:

[0117] A-1 to A-14: prepared by the preparation method of Preparation Examples 1 to 14;

[0118] B-1: Masson pine glyceride;

[0119] B-2: Elliptic pine glyceride;

[0120] B-3: special rosin resin;

[0121] B-4: rosin terpene phenol resin;

[0122] C-1: toluene diisocyanate;

[0123] C-2: Hexamethylene diisocyanate.

[0124] The adhesives were mixed and dispersed according to the compositions in Tables 1 to 3, respectively, and coated into double-sided tapes with a total thickness of 135 μm and a tissue paper substrate. The adhesives were dried at 90° C. for 3 min and aged at 50° C. for 24 h before evaluation.

[0125] Performance Evaluation

[0126] 180° peel strength test

[0127] Test principle: Test method for the force required to peel a double-sided adhesive tape or transfer adhesive tape with a 25μm polyester film on the surface from a stainless steel plate. A certain length of double-sided adhesive tape or transfer adhesive tape is pasted on a steel plate, and the steel plate is fixed in a fixture of a tensile testing machine. Another fixture clamps the free end of the sample and peels it continuously at 180°. The force required to continuously peel the moving double-sided adhesive tape or transfer adhesive tape from the steel plate is measured and converted into peel strength. Note that the peeling line is perpendicular to the direction of the force.

[0128] Reference standard: GB / T 2792-2014;

[0129] Testing instrument: computerized tape peeling force testing machine;

[0130] Test process: See GB / T 2792-2014 Method 3: Test method for 180° peel strength between double-sided adhesive tape, transfer adhesive tape and stainless steel.

[0131] Initial adhesion test

[0132] Test principle: The adhesion of adhesive to the adherend under slight pressure contact.

[0133] Reference standard: GB / T 4852-2002;

[0134] Testing instrument: Inclined rolling ball initial adhesion tester;

[0135] Test process: See GB / T 4852-2002 for details.

[0136] High temperature adhesion test

[0137] Test principle: When a weight of a specified weight is vertically suspended along the length of the pressure-sensitive adhesive tape attached to the adherend, the adhesive tape's ability to resist displacement is expressed by the time it takes for the test piece to move a certain distance or the distance it moves within a certain time.

[0138] Reference standard: GB / T 4851-2014;

[0139] Testing instrument: high temperature adhesion tester;

[0140] Test process: The test temperature is 80℃±1℃, and the remaining steps refer to GB / T4851-2014.

[0141] Constant load peeling (i.e. 90° static peel strength) test:

[0142] Test principle: Fix the steel plate with adhesive tape in a fixture in a high-temperature oven at 80°C, hang a weight of a specified weight at the free end of the adhesive tape, and peel the adhesive tape vertically from the surface of the steel plate.

[0143] Reference standard: GB / T 2792-2014;

[0144] Testing equipment: high temperature oven;

[0145] Test process: The steel plate to which the sample is attached is longitudinally polished with 280-grit sandpaper. The other indicators refer to the steel plate requirements in GB / T 2792-2014. The weight of the weight is 100g, the sample width is 20mm, and three sets of parallel samples are prepared.

[0146] The test temperature is 80℃±1℃.

[0147] After the sample is pasted, it is placed horizontally in a high-temperature oven at 80°C for 20 minutes. During the test, the peeling distance of the sample at 1 hour or the 5cm peeling time is recorded and the average value is taken.

[0148] VOC odor testing uses olfactory comparison.

[0149] The test results of the above embodiments and comparative examples are listed in Table 4 below.

[0150] Table 4

[0151]

[0152]

[0153] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0154] As a polar monomer, (meth)acrylic acid can increase the polarity of the copolymer, thereby helping to improve the adhesion of the adhesive to different substrates. The introduction of alkyl (meth)acrylates helps to provide good cohesion and heat resistance. The introduction of other functional monomers helps to further improve the cohesion, solvent resistance and temperature resistance of the pressure-sensitive adhesive. Controlling the mass ratio of (meth)acrylic acid, alkyl (meth)acrylates and other functional monomers within the above range helps to give full play to the synergistic effect of each copolymer, thereby helping to further improve the warping resistance and adhesion of the pressure-sensitive adhesive. Too high or too low an acid value may affect the stability, viscosity and compatibility of the adhesive with the substrate. Controlling the acid value of the copolymer within the above range helps to improve the adhesion of the adhesive.

[0155] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A copolymer, characterized in that The copolymer monomers of the copolymer include: (meth)acrylic acid, (meth)acrylic acid alkyl ester and other functional monomers, the mass ratio of the (meth)acrylic acid, the (meth)acrylic acid alkyl ester and the other functional monomers is 1:(20-35):(1.5-2), and the acid value of the copolymer is 10-15 mgKOH / g; the other functional monomers are selected from any one or more of olefin compounds, amide compounds and ester compounds.

2. The copolymer according to claim 1, characterized in that The weight average molecular weight of the copolymer is 450,000 to 1,000,000, preferably 450,000 to 650,000.

3. The copolymer according to claim 1 or 2, characterized in that The (meth)acrylic acid is acrylic acid and / or methacrylic acid; and / or, the alkyl (meth)acrylate is selected from any one or more of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexyl methacrylate, heptyl acrylate, heptyl methacrylate, octyl acrylate, isooctyl acrylate, octyl methacrylate, nonyl acrylate, nonyl methacrylate, decyl acrylate, decyl methacrylate, lauryl acrylate and lauryl methacrylate; preferably, the alkyl (meth)acrylate contains at least butyl acrylate; preferably, the alkyl (meth)acrylate is a combination of butyl acrylate and isooctyl acrylate, and the mass ratio of the butyl acrylate to the isooctyl acrylate is 2 to 4:1; And / or, the other functional monomers are selected from any one or more of styrene, acrylamide, N-hydroxymethyl acrylamide, vinyl acetate, tetrahydrofuran acrylate, tetrahydrofuran methacrylate, isobornyl acrylate, isobornyl methacrylate, dimethylaminomethyl acrylate, dimethylaminomethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminomethyl acrylate, diethylaminomethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate and hydroxybutyl methacrylate; preferably, the other functional monomers are hydroxyethyl acrylate and / or vinyl acetate; preferably, the other functional monomers are a combination of hydroxyethyl acrylate and vinyl acetate, and the mass ratio of the hydroxyethyl acrylate to the vinyl acetate is 1:20 to 60.

4. The copolymer according to any one of claims 1 to 3, characterized in that The raw material of the copolymer includes an initiator, the mass of the initiator is 0.5-1% of the mass of the monomer; and / or, the raw material of the copolymer includes a solvent, the mass of the solvent is 110-120% of the mass of the monomer; Preferably, the initiator is selected from any one or more of azobisisobutyronitrile, azobisisoheptanenitrile, azobisisovaleronitrile, dibenzoyl peroxide and 1,4-(di-tert-butylperoxycarbonyl)cyclohexane; and / or, the solvent is selected from any one or more of ethyl acetate, butyl acetate, toluene, xylene and N,N-dimethylformamide; Further preferably, the raw materials of the copolymer include the initiator and the solvent, the initiator is selected from any one or more of azobisisobutyronitrile, azobisisoheptanenitrile and azobisisovaleronitrile, and the solvent is selected from any one or more of ethyl acetate, butyl acetate and N,N-dimethylformamide.

5. A method for preparing the copolymer according to any one of claims 1 to 4, characterized in that: The preparation method comprises: placing raw materials including a comonomer, a solvent and an initiator in a reaction kettle for polymerization reaction to obtain the copolymer.

6. The preparation method according to claim 5, characterized in that: The polymerization reaction temperature is 65-70° C.; and / or the polymerization reaction time is 5-10 hours.

7. The preparation method according to claim 6, characterized in that: The comonomer, the solvent and the initiator are added in batches; preferably, the preparation method comprises: Step S1, adding 40-50% of the comonomer and 65-90% of the solvent as a base material into the reactor, by mass fraction; Step S2, adding 40-50% of the comonomer and 0.8-7% of the solvent as dropwise addition materials; Step S3, when the reactor is heated to 65-70°C, 15-25% of the initiator is added to the reactor and kept warm for 1-1.5 hours; then, the drop material is added dropwise to the reactor, and 10-40% of the initiator is added to the reactor during the drop material addition, and the drop material addition time is 1.5-3 hours. After the drop addition is completed, keep warm for 0.5-2 hours, add 4-5% of the monomer and 20-30% of the initiator into the reactor, keep warm for 1-2 hours, add the remaining comonomer, 0-3% of the solvent and the remaining initiator into the reactor, keep warm for 1-1.5 hours, add the remaining solvent into the reactor and terminate the polymerization reaction to obtain the copolymer.

8. The preparation method according to claim 7, characterized in that: During the dropwise addition of the dropwise addition material, 10-40% of the initiator is divided into 3-4 portions and added into the reaction kettle.

9. A pressure-sensitive adhesive, characterized in that: The pressure-sensitive adhesive comprises the following raw materials in parts by weight: 70 to 95 parts of the copolymer according to any one of claims 1 to 4; 5 to 30 parts of rosin resin; 0 to 5 parts of curing agent.

10. Use of the pressure-sensitive adhesive according to claim 9 in bonding automobile interior decoration.

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