Acrylate polymer for pressure-sensitive adhesive and preparation method and application thereof

Abstract

The invention discloses a method for synthesizing an acrylic polymer for a pressure-sensitive adhesive. The method comprises the following steps: 1) subjecting a first part of the polymerized raw materials to a first-stage polymerization reaction in a reactor, wherein the first part of the polymerized raw materials is composed of a first part of hard monomers, a first part of soft monomers, a first part of functional monomers, a first part of initiators and a first part of solvents, and the mass concentration of the first part of the monomers is 38.0%-42.0% in total; 2) adding a second part of the polymerized raw materials dropwise into the reactor, and subjecting the second stage of the polymerization reaction to the second stage, wherein the second part of the polymerized raw materials includes the remaining hard monomers, the remaining soft monomers, the remaining functional monomers, the second part of the initiators and the second part of the solvents, and the mass concentration of the second part of the monomers is 33.0%-37.0% in total; 3) adding the remaining initiators and the remaining solvents dropwise into the reactor, and subjecting the third stage of the polymerization reaction to the third stage. The method can prepare a polymer with a high molecular weight and a narrow distribution.

Description

Technical Field

[0001] The invention relates to an acrylate polymer for pressure-sensitive adhesive and a preparation method and application thereof. Background Art

[0002] Pressure-sensitive adhesives are a type of viscoelastic soft material that is sticky at room temperature and can bond to the surface of an adherend under external forces such as finger pressure. It is not only widely used in industry, agriculture, transportation and medical treatment, but also has great application potential in military and aerospace. Among them, acrylic pressure-sensitive adhesives (APSP) have become the most widely used pressure-sensitive adhesives due to their excellent bonding properties, oxidation resistance, low synthesis cost, high transparency and other advantages.

[0003] To meet the needs of different industries for pressure-sensitive adhesives, APSA can be divided into different types according to different synthetic production processes, including emulsion type, organic solvent type, hot melt type and radiation curing type. Among them, solvent-based and emulsion-based APSA still occupy the main market share. Although organic solvent-based APSA is not environmentally friendly, it still occupies an irreplaceable position.

[0004] The heat resistance and softness of pressure-sensitive adhesives need to be further improved. The initial tack, sustained tack and cohesive strength of pressure-sensitive adhesives need to be strictly controlled in some specific fields such as daily electronic equipment. These properties of pressure-sensitive adhesives are closely related to the physical and chemical properties of the main resin of the pressure-sensitive adhesive, such as the molecular weight and distribution of the main resin. Therefore, it is necessary to study how to prepare a main resin of a pressure-sensitive adhesive with a high molecular weight and a narrow molecular weight distribution. Summary of the invention

[0005] In view of the shortcomings and deficiencies of the prior art, the present invention provides an improved acrylic ester polymer for pressure-sensitive adhesive, which has a high molecular weight and a narrow molecular weight distribution. When applied to pressure-sensitive adhesive, the performance of the pressure-sensitive adhesive can be improved.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] The invention discloses a method for preparing an acrylic ester polymer for a pressure-sensitive adhesive. The method comprises the following steps: 1) subjecting a first part of polymer raw materials to a first stage polymerization reaction in a reaction kettle, wherein the first part of polymer raw materials comprises a first part of hard monomers, a first part of soft monomers, a first part of functional monomers, a first part of initiator and a first part of solvent, and the mass concentration of the first part of hard monomers, the first part of soft monomers and the first part of functional monomers is 38.0%-42.0% in total; 2) dripping a second part of polymer raw materials into the reaction kettle and carrying out a second stage polymerization reaction, wherein the second part of polymer raw materials comprises remaining hard monomers, remaining soft monomers, remaining functional monomers, a second part of initiator and a second part of solvent, and the mass concentration of the remaining hard monomers, remaining soft monomers and remaining functional monomers is 33.0%-37.0% in total; 3) dripping the remaining initiator and the remaining solvent into the reaction kettle and carrying out a third stage polymerization reaction, and after the reaction is completed, the acrylic ester polymer for the pressure-sensitive adhesive is obtained.

[0008] In some embodiments, after the remaining initiator and the remaining solvent are added dropwise, the total mass of the monomers added dropwise into the reactor accounts for 28.0% to 32.0% of the total mass of the monomers and the total mass of the solvents added dropwise.

[0009] In some embodiments, the total mass concentration of the first portion of hard monomers, the first portion of soft monomers, and the first portion of functional monomers is 39.8%-40.2%.

[0010] Preferably, the total mass concentration of the first portion of hard monomers, the first portion of soft monomers and the first portion of functional monomers is 40.0%.

[0011] In some embodiments, the total mass concentration of the remaining hard monomers, the remaining soft monomers, and the remaining functional monomers is 34.8%-35.2%.

[0012] Preferably, the total mass concentration of the remaining hard monomers, the remaining soft monomers and the remaining functional monomers is 35.0%.

[0013] In some embodiments, after the remaining initiator and the remaining solvent are added dropwise, the total mass of the monomers added dropwise into the reactor accounts for 29.8% to 30.2% of the total mass of the monomers and the total mass of the solvents added dropwise.

[0014] Preferably, after the remaining initiator and the remaining solvent are added dropwise, the total mass of the monomers added dropwise into the reactor accounts for 30.0% of the total mass of the monomers and the total mass of the solvents added dropwise.

[0015] In some embodiments, the temperature of the first stage polymerization reaction is 59-61°C.

[0016] In some embodiments, the temperature of the second stage polymerization reaction is 59-61°C.

[0017] In some embodiments, the temperature of the third stage polymerization reaction is 59-61°C.

[0018] If the temperature of the polymerization reaction in the first stage, the second stage and the third stage is too high or too low, it is not conducive to the control of the molecular weight and distribution of the acrylate polymer.

[0019] In some embodiments, the first stage polymerization reaction time is 1.5-2.5 hours.

[0020] In some embodiments, the second stage polymerization reaction time is 2.5-3.5 hours.

[0021] In some embodiments, the third stage polymerization reaction time is 1.5-2.5 hours.

[0022] In some embodiments, the first stage polymerization reaction, the second stage polymerization reaction, and the third stage polymerization reaction are all carried out under stirring, and the stirring rate is 170-190 r / min.

[0023] Preferably, the first stage polymerization reaction, the second stage polymerization reaction and the third stage polymerization reaction are all carried out under stirring, and the stirring rate is 180r / min.

[0024] In some embodiments, in step 2), the dripping time is 20-40 min, and the dripping rate is 13-17 ml / min. In the second stage polymerization reaction, too slow or too fast dripping rate is not conducive to the control of the molecular weight and distribution of the acrylate polymer.

[0025] In some embodiments, the first stage polymerization reaction, the second stage polymerization reaction, and the third stage polymerization reaction are all carried out under water bath temperature control, and the initial temperature of the water bath is set to 59-61°C. When the first stage polymerization reaction is carried out for 30 minutes, the water bath temperature is set to 55-57°C and maintained for 10 minutes, and then the water bath temperature is set to 59-61°C again.

[0026] Preferably, the first stage polymerization reaction, the second stage polymerization reaction, and the third stage polymerization reaction are all carried out under water bath temperature control, and the initial temperature of the water bath is set to 60°C. When the first stage polymerization reaction is carried out for 30 minutes, the water bath temperature is set to 56°C and lasts for 10-15 minutes, and then the water bath temperature is set to 60°C again. When the first stage polymerization reaction is carried out for 30 minutes, the polymerization reaction system releases heat quickly, which easily leads to excessively high local material temperature in the reactor, which is not conducive to the control of the molecular weight distribution of the polymer. At this time, appropriately lowering the water bath temperature can alleviate the rapid rise in the temperature of the polymerization raw materials in the reactor, which is conducive to the stable progress of the polymerization.

[0027] In some embodiments, the hard monomer is methyl methacrylate.

[0028] In some embodiments, the soft monomer is selected from butyl acrylate or isooctyl acrylate.

[0029] In some embodiments, the functional monomer is selected from hydroxyethyl acrylate or hydroxybutyl acrylate.

[0030] In some embodiments, the initiator is azobisisoheptanonitrile.

[0031] In some embodiments, the solvent is ethyl acetate.

[0032] In some embodiments, the molar ratio of the first part of hard monomers, the first part of soft monomers, the first part of functional monomers and the first part of initiator is 2-40:270-4100:2-40:1.

[0033] Preferably, the molar ratio of the first part of hard monomers, the first part of soft monomers, the first part of functional monomers and the first part of initiator is 36.5:4040:36.5:1.

[0034] In some embodiments, the molar ratio of the remaining hard monomer, the remaining soft monomer, the remaining functional monomer and the second portion of the initiator is 30-42:4000-4100:30-42:1.

[0035] Preferably, the molar ratio of the remaining hard monomer, the remaining soft monomer, the remaining functional monomer and the second part of the initiator is 35.8:4034:35.8:1.

[0036] In some embodiments, the remaining initiator accounts for 18-22% of the total mass of the first part of initiator and the second part of initiator.

[0037] Preferably, the mass of the remaining initiator accounts for 20% of the total mass of the first part of initiator and the second part of initiator.

[0038] The present invention also provides an acrylic ester polymer for pressure-sensitive adhesive prepared by the above-mentioned preparation method, which has a molecular weight of more than 200,000 and a molecular weight distribution of less than 1.74.

[0039] The invention also provides use of the acrylate polymer for pressure-sensitive adhesive in pressure-sensitive adhesive.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] The present invention feeds monomers, initiators and solvents in batches, feeds part of the monomers, part of the initiators and part of the solvents in the first and second feedings, and feeds only the remaining initiators and the remaining solvents in the third feeding, controls the mass concentration of the monomers in the first and second feedings, and the amount of the solvent added in the third stage for dilution, and performs three-stage polymerization reactions accordingly, so as to effectively control the molecular weight and distribution of the acrylate polymer, and obtain the acrylate polymer with high molecular weight and narrow molecular weight distribution. When the polymer is used in the pressure-sensitive adhesive, it is expected to significantly improve various properties of the pressure-sensitive adhesive.

[0042] The present invention uses a water bath to control the temperature of the polymerization reaction system. When the first stage polymerization reaction is carried out for 30 minutes, the water bath temperature is slightly reduced for 10-15 minutes to alleviate the excessively fast temperature of the local polymerization raw materials caused by the exothermic polymerization reaction, and the molecular weight distribution of the acrylate polymer can be well controlled.

[0043] The present invention can improve the molecular weight and distribution of the polymer by controlling the rate of dripping the polymerization raw material into the reaction kettle during the second stage polymerization reaction.

[0044] The acrylic ester polymer for pressure-sensitive adhesive prepared by the invention has a colorless and transparent appearance, does not change color when exposed to sunlight for a long time, and is not easy to age. The acrylic ester polymer for pressure-sensitive adhesive has a high molecular weight, a narrow molecular weight distribution, and a low monomer residual content. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is the NMR image of the acrylate polymer for pressure-sensitive adhesive prepared in Example 1;

[0046] Figure 2 This is the GPC spectrum of the acrylic ester polymer for pressure-sensitive adhesive prepared in Example 1. DETAILED DESCRIPTION

[0047] The present invention is further described below in conjunction with the examples. However, the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in each embodiment of the present invention can be combined with each other as long as they do not conflict with each other.

[0048] Example 1

[0049] This embodiment provides an acrylate polymer for a pressure-sensitive adhesive, and the preparation steps thereof are as follows:

[0050] First, check the air tightness of the device and whether the various devices and equipment of the reactor are operating normally. After confirming that there are no problems, weigh various raw materials according to the amounts in Table 1 below.

[0051] Methyl methacrylate MMA, butyl acrylate BA, hydroxybutyl acrylate HBA, solvent ethyl acetate EA and initiator azobisisoheptanenitrile ABVN of the first polymerization stage are added into the reactor, and the materials of the second polymerization stage: methyl methacrylate, butyl acrylate, hydroxybutyl acrylate, ethyl acetate and initiator azobisisoheptanenitrile are weighed according to the amounts in Table 1 below, and added into the constant pressure dropping funnel, and the constant pressure dropping funnel is installed on one port of the reactor; nitrogen is bubbled into the reactor and the constant pressure dropping funnel at the same time for one hour.

[0052] The reactor was placed in a circulating water bath with a thermometer installed in it. The external heating device was turned on to start heating and the circulating water bath was turned on. When the temperature in the reactor reached 60°C, the first stage polymerization reaction was started. The reaction was carried out under stirring at a stirring rate of 180r / min. When the reaction lasted for 30 minutes, the circulating water bath was cooled to 56°C. After 10 minutes, the circulating water bath was further heated to 60°C to continue the first stage polymerization reaction. The total duration of the first stage polymerization reaction was 2 hours.

[0053] The second polymerization stage material was added dropwise into the reactor from the constant pressure dropping funnel, and the second stage polymerization reaction was carried out at a dropping rate of 15 ml / min. After the addition was completed, the reaction was continued. During the whole process, the temperature of the circulating water bath and the reactor was controlled at 60°C. The reaction was carried out under stirring at a stirring rate of 180 r / min. The total duration of the second stage polymerization reaction was 3 hours.

[0054] The materials for the third polymerization stage, including ethyl acetate and initiator azobisisoheptanonitrile, were added dropwise to the reactor, as shown in Table 1 below. After the addition was completed, the reaction continued. During the whole process, the temperature of the circulating water bath and the reactor was controlled at 60° C. The reaction was carried out under stirring at a stirring rate of 180 r / min. The total duration of the third stage polymerization reaction was 2 hours.

[0055] After the polymerization is completed, the polymer is discharged from the discharge port of the reactor to obtain an acrylate polymer. Deuterated chloroform is used for nuclear magnetic resonance testing, and the results are as follows: Figure 1 As shown, it can be seen that the polymer was successfully synthesized. The polymer was tested by GPC, and the result showed that the number average molecular weight was 470,000 and the molecular weight distribution PDI was 1.56. Figure 2 shown.

[0056] Example 2

[0057] This embodiment provides an acrylate polymer for pressure-sensitive adhesive, and its preparation steps are basically the same as those in Example 1, except that the amount of raw materials added in each polymerization stage is slightly different, as shown in Table 1 below. The molecular weight and distribution of the finally obtained acrylate polymer are shown in Table 1 below.

[0058] Example 3

[0059] This embodiment provides an acrylate polymer for pressure-sensitive adhesive, and its preparation steps are basically the same as those in Example 1, except that the amount of raw materials added in each polymerization stage is slightly different, as shown in Table 1 below. The molecular weight and distribution of the finally obtained acrylate polymer are shown in Table 1 below.

[0060] Table 1 Materials added in each polymerization stage of each embodiment

[0061]

[0062]

[0063] Comparative Example 1

[0064] This comparative example provides an acrylic ester polymer for a pressure-sensitive adhesive, and its preparation steps are basically the same as those of Example 1, except that the mass concentration of the monomers in the first polymerization stage is different, and the materials in each polymerization stage are shown in Table 1.

[0065] Comparative Example 2

[0066] This comparative example provides an acrylic ester polymer for a pressure-sensitive adhesive, and its preparation steps are basically the same as those of Example 1, except that the mass concentration of the monomers in the second polymerization stage is different, and the materials in each polymerization stage are shown in Table 1.

[0067] Comparative Example 3

[0068] This comparative example provides an acrylate polymer for pressure-sensitive adhesive, and its preparation steps are basically the same as those in Example 1, except that the dripping rate of the material in the second polymerization stage is 43 ml / min. As a result, the molecular weight of the obtained acrylate polymer is 35W and the PDI is 1.82.

[0069] Comparative Example 4

[0070] This comparative example provides an acrylate polymer for pressure-sensitive adhesive, and its preparation steps are basically the same as those in Example 1, except that the dripping rate of the material in the second polymerization stage is 7 ml / min. As a result, the molecular weight of the obtained acrylate polymer is 20W and the PDI is 2.2.

[0071] Comparative Example 5

[0072] This comparative example provides an acrylate polymer for a pressure-sensitive adhesive, and its preparation steps are basically the same as those of Example 1, except that the circulating water bath temperature is always set to 60° C. during the first stage polymerization reaction. As a result, the molecular weight of the obtained acrylate polymer is 15W and the PDI is 2.5.

[0073] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

[0074] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

Claims

1. A method for preparing an acrylic acid ester polymer for a pressure-sensitive adhesive, It is characterized in that The preparation method comprises the following steps: 1) subjecting a first part of polymer raw materials to a first stage polymerization reaction in a reactor, wherein the first part of polymer raw materials consists of a first part of hard monomers, a first part of soft monomers, a first part of functional monomers, a first part of initiator and a first part of solvent, and the mass concentration of the first part of hard monomers, the first part of soft monomers and the first part of functional monomers is 38.0%-42.0% in total; 2) adding a second part of polymer raw materials dropwise into the reactor and subjecting the second stage polymerization reaction to the second stage polymerization reaction, wherein the second part of polymer raw materials comprises remaining hard monomers, remaining soft monomers, remaining functional monomers, a second part of initiator and a second part of solvent, and the mass concentration of the remaining hard monomers, the remaining soft monomers and the remaining functional monomers is 33.0%-37.0% in total; 3) dropping the remaining initiator and the remaining solvent into the reactor, and carrying out the third stage polymerization reaction, after the reaction is completed, the acrylate polymer for pressure-sensitive adhesive is obtained; in step 2), the dropping time is 20-40min, and the dropping rate is 13-17ml / min; the first stage polymerization reaction, the second stage polymerization reaction, and the third stage polymerization reaction are all carried out under water bath temperature control, and the initial temperature of the water bath is set to 59-61°C. When the first stage polymerization reaction is carried out for 30min, the water bath temperature is set to 55-57°C and continued for 10-15min, and then the water bath temperature is set to 59-61°C again; after dropping the remaining After the initiator and the remaining solvent are added, the monomers added dropwise into the reactor account for 28.0%-32.0% of the total mass of the monomers and the solvent added dropwise; the hard monomer is methyl methacrylate; the soft monomer is selected from butyl acrylate or isooctyl acrylate; the functional monomer is selected from hydroxyethyl acrylate or hydroxybutyl acrylate; the molar ratio of the first part of hard monomer, the first part of soft monomer, the first part of functional monomer and the first part of initiator is 2-40:270-4100:2-40:1; the molar ratio of the remaining hard monomer, the remaining soft monomer, the remaining functional monomer and the second part of initiator is 30-42:4000-4100:30-42:

1.

2. The method for preparing the acrylic ester polymer for pressure-sensitive adhesive according to claim 1, Features: The total mass concentration of the first part of hard monomers, the first part of soft monomers and the first part of functional monomers is 39.8%-40.2%.

3. The method for preparing the acrylic ester polymer for pressure-sensitive adhesive according to claim 1, Features: The total mass concentration of the remaining hard monomers, the remaining soft monomers and the remaining functional monomers is 34.8%-35.2%.

4. The method for preparing the acrylic ester polymer for pressure-sensitive adhesive according to claim 1, Features: The time of the first stage polymerization reaction is 1.5-2.5 hours; and / or, the time of the second stage polymerization reaction is 2.5-3.5 hours; and / or, the time of the third stage polymerization reaction is 1.5-2.5 hours.

5. The method for preparing the acrylic ester polymer for pressure-sensitive adhesive according to claim 1, Features: The first stage polymerization reaction, the second stage polymerization reaction and the third stage polymerization reaction are all carried out under stirring, and the stirring rate is 170-190r / min.

6. The method for preparing the acrylic ester polymer for pressure-sensitive adhesive according to claim 1, Features: After the remaining initiator and the remaining solvent are added dropwise, the total weight of the monomers added dropwise into the reaction kettle accounts for 29.8% to 30.2% of the total weight of the monomers and the total weight of the solvents added dropwise.

7. The method for preparing the acrylic ester polymer for pressure-sensitive adhesive according to claim 1, Features: The initiator is azobisisoheptanonitrile.

8. The method for preparing the acrylic ester polymer for pressure-sensitive adhesive according to claim 1, Features: The solvent is ethyl acetate.

9. The method for preparing the acrylic ester polymer for pressure-sensitive adhesive according to claim 1, Features: The mass of the remaining initiator accounts for 18-22% of the total mass of the first part of initiator and the second part of initiator.

Images