Acrylic pressure-sensitive adhesive for polyester materials and method for preparing the same

Abstract

The present application relates to a kind of acrylic pressure sensitive adhesive for polyester material and its preparation method, belong to pressure sensitive adhesive technical field.The pressure sensitive adhesive acrylic base monomer and branched hydroxyl modified monomer prepolymers, then mixed with crosslinking agent, super micro filler and film forming aid can be chelated in turn drying, ultraviolet irradiation crosslinking glue;Branched hydroxyl modified monomer is made into acryloyl intermediate by amidation reaction of acryloyl chloride and imino diacetic acid diethyl ester, then by diethanolamine and acryloyl intermediate amine ester exchange reaction, introduce multiple branched hydroxyl modification;Branched hydroxyl modified monomer is introduced to the macromolecular side chain of copolymer with cluster branched hydroxyl, form gradient polarity distribution on side chain, significantly reduce the surface tension of glue, realize the molecular level wetting to polyester substrate, and form tough interface layer with polyester surface by hydrogen bond effect, plus its polyamide structure and the chelation effect of calcium carbonate filler improves the thermal shock bonding performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pressure-sensitive adhesive, and particularly relates to an acrylic pressure-sensitive adhesive for polyester materials and a preparation method thereof. BACKGROUND

[0002] The acrylic pressure-sensitive adhesive is a kind of high polymer material that can be quickly bonded by slight pressure, and the core film-forming substance thereof is an acrylate copolymer. The traditional acrylic pressure-sensitive adhesive is usually provided with butyl acrylate, isooctyl acrylate and other soft monomers to provide adhesion, is adjusted in cohesion strength by combining with acrylate, hydroxyethyl acrylate and other hard monomers, and is supplemented with a crosslinking agent to construct a three-dimensional network structure. The pressure-sensitive adhesive has excellent weather resistance, high transparency, solvent-free environmental protection and other advantages, and is widely applied in fields such as electronic device packaging, optical film layer compounding and automobile interior decoration bonding.

[0003] With the popularity of polyester (PET, PBT, etc.) materials in the fields of flexible circuit boards, lithium battery separators and optical films, the acrylic pressure-sensitive adhesive for polyester materials in the prior art has the following main defects:

[0004] The traditional acrylate copolymer has low polarity and is difficult to fully wet the surface of the polyester, so a corona treatment or a primer coating agent is needed to improve the interfacial bonding force. Such a pretreatment process increases the production cost, and the corona effect easily decays with time, limiting its application in the precision electronics field.

[0005] In order to improve the wettability, the prior art proposes to add fluorocarbon surfactants or organosiloxanes as wetting aids. However, such small molecules are easy to migrate to the interface of the adhesive layer, which destroys the cohesion strength of the acrylic copolymer. Especially under thermal shock, shear stress concentration is easily generated at the interface, which causes micro-crack propagation, and finally leads to bonding failure, greatly limiting the application of the acrylic pressure-sensitive adhesive in the bonding of polyester materials. SUMMARY

[0006] In order to solve the technical problems mentioned in the background art, the purpose of the present application is to provide an acrylic pressure-sensitive adhesive for polyester materials and a preparation method thereof.

[0007] The purpose of the present application can be achieved by the following technical solutions:

[0008] An acrylic pressure-sensitive adhesive for polyester materials is prepared by pre-polymerizing acrylic monomers and branched hydroxyl modified monomers, then mixing with a crosslinking agent, a chelatable ultra-fine filler and a film-forming aid, and then drying, ultraviolet irradiation and crosslinking in sequence to prepare the adhesive.

[0009] The preparation method of the branched hydroxyl modified monomer is as follows:

[0010] Step A1: iminodiacetic acid diethyl ester and anhydrous tetrahydrofuran are mixed, dry nitrogen is introduced to replace air, and an ice water bath is used to cool to 0-5℃. Acryloyl chloride and triethylamine are added while stirring, and the addition rate is controlled to keep the temperature of the reaction system below 10℃. After the reaction is completed, the salt is removed by filtration, and tetrahydrofuran is removed by reduced pressure distillation to obtain the acryloyl intermediate;

[0011] In the above step A1 reaction, the amount of iminodiacetic acid diethyl ester, acryloyl chloride, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.1 mol: 10-13 mL: 120-150 mL. In the presence of triethylamine, acryloyl chloride reacts with iminodiacetic acid diethyl ester. The specific reaction route is as follows:

[0012]

[0013] Step A2: The acryloyl intermediate, diethanolamine, and anhydrous toluene are mixed, dry nitrogen is introduced to replace air, and then trimethylaluminum is added and mixed. The temperature is preheated to 40-55℃ and stirred for 3-4h. Then the temperature is further increased to 100-110℃ and refluxed for 1.5-2h. After the reaction is completed, deionized water is added and mixed, and the low boiling point solvent mainly toluene is removed by reduced pressure distillation to obtain the branched hydroxyl modified monomer.

[0014] In the above step A2 reaction, the amount of acryloyl intermediate, diethanolamine, trimethylaluminum, and anhydrous toluene is 0.1 mol: 0.2 mol: 0.6-0.9 mL: 80-100 mL. In the presence of trimethylaluminum, diethanolamine undergoes amine-ester exchange with the acryloyl intermediate. The specific reaction route is as follows:

[0015]

[0016] A method for preparing an acrylic pressure-sensitive adhesive for a polyester material, specifically:

[0017] Step S1: The acrylic monomer, branched hydroxyl modified monomer, and ethyl acetate are mixed, nitrogen is introduced to replace air, the temperature is increased to 70-80℃, and azobisisobutyronitrile solution is slowly added and stirred for 2.5-3.2h to obtain a prepolymer.

[0018] Step S2: The crosslinking agent, chelatable ultra-fine filler, and film-forming aid are added to the prepolymer and mixed, vacuum degassing is performed, and then coated on the surface of the carrier. After hot air drying and UV irradiation crosslinking, an acrylic pressure-sensitive adhesive is obtained.

[0019] Further, in the prepolymehsion process, the branched hydroxyl modified monomer is 15-22wt% of the acrylic monomer. With this amount of modification, the prepared adhesive has good wettability and bonding stability.

[0020] Preferably, the acrylic acid-based monomer is compounded from acrylic acid, isooctyl acrylate and butyl acrylate in a molar ratio of 1:1.5-2:0.5-1, which has good stability and adhesion of the adhesive layer.

[0021] Preferably, the crosslinking agent is compounded from trimethylolpropane triacrylate and triethylene glycol dimethacrylate, which has good controllable crosslinking activity and is conducive to controlling the state of the adhesive layer.

[0022] Preferably, the chelatable ultra-fine filler is sub-micron calcium carbonate, which interacts with the block segment of the branched hydroxyl modified monomer to strengthen the adhesive layer.

[0023] The beneficial effects of the present application are:

[0024] The present application discloses a branched hydroxyl modified monomer and an existing acrylic ester copolymer as a film-forming material, which is prepared by amidation reaction of acryloyl chloride and imino diacetate diethyl ester to form an acryloyl intermediate, and then amine ester exchange reaction of diethanolamine and the acryloyl intermediate to introduce a branched hydroxyl modified monomer. The branched hydroxyl modified monomer introduces a cluster branched hydroxyl group into the side chain of the copolymer, forms a gradient polarity distribution on the side chain, significantly reduces the surface tension of the colloid, realizes molecular-level wetting of the polyester substrate, and significantly improves the adhesion strength of the pressure-sensitive adhesive. The multi-hydroxyl structure introduced by the branched hydroxyl modified monomer into the side chain forms a hydrogen bond with the surface of the polyester matrix to form a tough interface layer, and its multi-amide structure and chelation effect of calcium carbonate filler construct a heat-resistant network, so that the adhesive layer maintains stable adhesion under thermal shock, realizing stable adhesion of the pressure-sensitive adhesive to the polyester substrate. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0026] Example 1, preparation of an acrylic pressure-sensitive adhesive for polyester material, as follows:

[0027] (1) Synthesis of branched hydroxyl modified monomer

[0028] Step A1: Take imino diacetic acid diethyl ester and anhydrous tetrahydrofuran, replace air with dry nitrogen, cool to 0℃ with ice water bath, stir at 120rpm, and drop acryloyl chloride and triethylamine while controlling the speed to keep the temperature of the reaction system below 10℃. After 10h of reaction at room temperature, filter out the salt, and remove tetrahydrofuran under reduced pressure to obtain the acryloyl intermediate.

[0029] Step A2: Take the acryloyl intermediate, diethanolamine, and anhydrous toluene, replace air with dry nitrogen, add trimethylaluminum, preheat to 40℃, stir at 60rpm for 4h, and then continue to heat to 100℃ for 2h. The ratio of the acryloyl intermediate, diethanolamine, trimethylaluminum, and anhydrous toluene is 0.1mol:0.2mol:0.6mL:80mL. After the reaction is completed, add deionized water, wash, remove the low-boiling solvent mainly toluene under reduced pressure, and obtain the branched hydroxyl-modified monomer.

[0030] (2) Preparation of pressure-sensitive adhesive

[0031] Step S1: Take acrylic acid, isooctyl acrylate, and butyl acrylate according to the molar ratio 1:2:0.5 to prepare the acrylic monomer. Add 15wt% of the branched hydroxyl-modified monomer to the acrylic monomer as the substrate, add 40wt% of ethyl acetate to the substrate to stir uniformly, replace air with nitrogen, heat to 70℃, take 0.2wt% of azobisisobutyronitrile dissolved in acetone and added to the substrate, stir for 3.2h, and then cool to below 40℃ using circulating cooling water to discharge the product, obtaining the prepolymer.

[0032] Step S2: Take trimethylolpropane triacrylate and triethylene glycol dimethacrylate according to the molar ratio 1:5 to prepare the crosslinking agent, with a dosage of 3.2wt% of the substrate. Take commercially available submicron calcium carbonate with an average particle size of 800nm as the chelatable ultrafine filler, with a dosage of 5.5wt% of the substrate. Take commercially available KMT-1020 leveling agent and KMT-2046 defoaming agent to prepare the film-forming aid, with dosages of 0.2wt% and 0.3wt%, respectively. Add the crosslinking agent, chelatable ultrafine filler, and film-forming aid to the prepolymer, vacuum degassing, and then coated on the surface of the specific sheet carrier, sent to the 80℃ oven for 10min of hot air drying, and irradiated for 15s using a UV mercury lamp at 60mW / cm 2 to obtain the acrylic pressure-sensitive adhesive.

[0033] Example 2, preparation of the acrylic pressure-sensitive adhesive for polyester materials, as follows:

[0034] (1) Synthesis of branched hydroxyl modified monomer

[0035] Step A1: Take iminodiacetic acid diethyl ester and anhydrous tetrahydrofuran, replace air with dry nitrogen, cool to 0°C with ice water bath, stir at 150 rpm, and drop acryloyl chloride and triethylamine while controlling the speed to keep the temperature of the reaction system below 10°C. After that, stir at room temperature for 9.5 hours. The ratio of iminodiacetic acid diethyl ester, acryloyl chloride, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.1 mol: 11 mL: 130 mL. After the reaction is completed, remove the salt by filtration and remove tetrahydrofuran by reduced pressure distillation to obtain the acryloyl intermediate.

[0036] Step A2: Take the acryloyl intermediate, diethanolamine, and anhydrous toluene, replace air with dry nitrogen, and then add and mix trimethylaluminum. Preheat to 50°C, stir at 60 rpm for 3.5 hours, and then continue to heat to 100°C for 1.8 hours. The ratio of the acryloyl intermediate, diethanolamine, trimethylaluminum, and anhydrous toluene is 0.1 mol: 0.2 mol: 0.7 mL: 90 mL. After the reaction is completed, add deionized water to mix and wash, remove the low-boiling solvent mainly toluene by reduced pressure distillation to obtain the branched hydroxyl modified monomer.

[0037] (2) Preparation of pressure-sensitive adhesive

[0038] Step S1: Take acrylic acid, isooctyl acrylate, and butyl acrylate to be compounded as acrylic-based monomers according to a molar ratio of 1:1.8:0.6. Add 18wt% of the branched hydroxyl modified monomer mixed as the substrate to the acrylic-based monomers. Add 45wt% of ethyl acetate to the substrate to stir uniformly. Replace air with nitrogen, heat to 75°C, take 0.2wt% of azobisisobutyronitrile dissolved in acetone to add to the substrate, stir for 2.8 hours, and then cool to below 40°C using circulating cooling water after the reaction is completed to discharge to obtain the prepolymer.

[0039] Step S2: Take trimethylolpropane triacrylate and triethylene glycol dimethacrylate to be premixed as cross-linking agents according to a molar ratio of 1:5, with a usage of 3.5wt% of the substrate. Take commercially available sub-micron calcium carbonate with an average particle size of 800nm as chelatable ultra-fine filler, with a usage of 6.5wt% of the substrate. Take commercially available KMT-1020 type leveling agent and KMT-2046 type defoaming agent to be mixed as film-forming aids, with a usage of 0.15wt% and 0.35wt% respectively. Add the above cross-linking agent, chelatable ultra-fine filler, and film-forming aid to the prepolymer, vacuum degassing, and then coated on the surface of the specific sheet carrier, sent to the 80°C oven for hot air drying for 10 minutes. Use a UV mercury lamp to irradiate for 15 seconds at a power of 60mW / cm 2 to obtain the acrylic pressure-sensitive adhesive.

[0040] Example 3, preparation of acrylic pressure sensitive adhesive for polyester material, as follows:

[0041] (1) Synthesis of branched hydroxyl modified monomer

[0042] Step A1: Take imino diethyl acid diethyl ester and anhydrous tetrahydrofuran, replace air with dry nitrogen, cool to 5°C with ice water bath, stir at 150 rpm, and drop acryloyl chloride and triethylamine while controlling the speed to keep the temperature of the reaction system below 10°C. Then, stir at room temperature for 8 hours. The ratio of imino diethyl acid diethyl ester, acryloyl chloride, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol:0.1 mol:13 mL:150 mL. After the reaction is completed, remove the salt by filtration and remove tetrahydrofuran by reduced pressure distillation to obtain the acryloyl intermediate.

[0043] Step A2: Take the acryloyl intermediate, diethanolamine, and anhydrous toluene, replace air with dry nitrogen, and then add and mix trimethylaluminum. Preheat to 55°C, stir at 60 rpm for 3 hours, and then continue to heat to 110°C and reflux for 1.5 hours. The ratio of acryloyl intermediate, diethanolamine, trimethylaluminum, and anhydrous toluene is 0.1 mol:0.2 mol:0.9 mL:100 mL. After the reaction is completed, add deionized water and mix to wash, remove the low-boiling solvent mainly with toluene by reduced pressure distillation to obtain the branched hydroxyl modified monomer.

[0044] (2) Preparation of pressure sensitive adhesive

[0045] Step S1: Take acrylic acid, isooctyl acrylate, and butyl acrylate and mix them according to a molar ratio of 1:1.5:1 as acrylic monomers. Add 22wt% of the branched hydroxyl modified monomer to the acrylic monomers as a substrate, add 50wt% of ethyl acetate to the substrate and stir until uniform. Replace air with nitrogen, heat to 80°C, take 0.2wt% of azobisisobutyronitrile in the substrate and add it to the mixture after dissolving in acetone. Stir for 2.5 hours, and then cool to below 40°C using circulating cooling water after the reaction is completed to obtain the prepolymer.

[0046] Step S2: Take trimethylolpropane triacrylate and triethylene glycol dimethacrylate and pre-mix them according to a molar ratio of 1:5 as a crosslinking agent, with a dosage of 3.8wt% of the substrate; take commercially available sub-micron calcium carbonate with an average particle size of 800 nm as a chelatable ultra-fine filler, with a dosage of 5.5wt% of the substrate; take commercially available KMT-1020 leveling agent and KMT-2046 defoaming agent and mix them as a film-forming aid, with dosages of 0.15wt% and 0.4wt%, respectively; add the above crosslinking agent, chelatable ultra-fine filler, and film-forming aid to the prepolymer, vacuum degas, and then coat on the surface of the specific sheet carrier, and then send it into an 80°C oven for 10 minutes of hot air drying. Use a UV mercury lamp with an intensity of 60 mW / cm 2The irradiation was performed for 15 s to obtain the acrylic pressure-sensitive adhesive.

[0047] Example 4, preparation of acrylic pressure-sensitive adhesive for polyester material, as follows:

[0048] (1) Synthesis of branched hydroxyl modified monomer

[0049] Step A1: Take imino diethyl acid diethyl ester and anhydrous tetrahydrofuran, replace air with dry nitrogen, cool to 5°C with ice water bath, stir at 150 rpm, and drop acryloyl chloride and triethylamine while controlling the addition rate to keep the reaction system temperature below 10°C. Then, stir at room temperature for 8.5 h. The amount ratio of imino diethyl acid diethyl ester, acryloyl chloride, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol:0.1 mol:12 mL:140 mL. After the reaction is completed, remove the salt by filtration and remove tetrahydrofuran by reduced pressure distillation to obtain the acryloyl intermediate.

[0050] Step A2: Take the acryloyl intermediate, diethanolamine, and anhydrous toluene, replace air with dry nitrogen, and then add trimethylaluminum and mix. Preheat to 45°C, stir at 60 rpm for 4 h, and then continue to heat to 100°C for 1.7 h. The amount ratio of acryloyl intermediate, diethanolamine, trimethylaluminum, and anhydrous toluene is 0.1 mol:0.2 mol:0.7 mL:90 mL. After the reaction is completed, add deionized water and mix to wash, remove the low-boiling solvent mainly with solvent toluene by reduced pressure distillation to obtain the branched hydroxyl modified monomer.

[0051] (2) Preparation of pressure-sensitive adhesive

[0052] Step S1: Take acrylic acid, isooctyl acrylate, and butyl acrylate to be compounded as acrylic-based monomers according to the molar ratio of 1:1.6:0.9, add 20 wt% branched hydroxyl modified monomer to the acrylic-based monomers as the substrate, add 47 wt% ethyl acetate to the substrate to stir uniformly, replace air with nitrogen, heat to 80°C, take 0.2 wt% azobis isobutyronitrile in the substrate dissolved in acetone, and then add and mix, stir for 3 h, and then cool to below 40°C with circulating cooling water after the reaction is completed to discharge, to obtain the prepolymer.

[0053] Step S2: take trimethylolpropane triacrylate and triethylene glycol dimethacrylate as a crosslinking agent, and the amount is 3.5wt% of the substrate; take commercially available sub-micron calcium carbonate with an average particle size of 800nm as a chelatable ultra-fine filler, and the amount is 7wt% of the substrate; take commercially available KMT-1020 type leveling agent and KMT-2046 type defoaming agent as a film forming aid, and the amount is 0.2wt% and 0.35wt% respectively; add the above crosslinking agent, chelatable ultra-fine filler and film forming aid to the prepolymer mixture, and after vacuum degassing, it is coated on the surface of the specific sheet carrier, and then sent into an 80℃ oven for hot air drying for 10min, and then the UV mercury lamp is used at 60mW / cm 2 Irradiate for 15s to obtain an acrylic pressure-sensitive adhesive.

[0054] Comparative Example 1: commercially available CF-628A type high-strength acrylic pressure-sensitive adhesive is selected.

[0055] Comparative Example 2: referring to the implementation process of Example 4, the branched hydroxyl modified monomer is replaced with an equal amount of hydroxyethyl acrylate, and the rest of the implementation process is the same.

[0056] Comparative Example 3: referring to the implementation process of Comparative Example 2, 2.2wt% of TEGO® Wet260 type wetting agent is added during the glue preparation process, and the rest of the implementation process is the same.

[0057] Sample the pressure-sensitive adhesive prepared as above, detect the initial adhesion according to the GB / T 4852-2002 standard by using the inclined plane ball method; according to the GB / T 4851-2014 standard, the pressure-sensitive adhesive is attached to the polyester plate, and the holding adhesion is detected under a load of 1kg; according to the GB / T 2792-2014 standard, the peeling strength is detected at a peeling speed of 25mm / min at room temperature; the sample after attachment is placed in a 60℃ oven for heat treatment for 1h, and then air-cooled to room temperature, and then heat cycle treatment is performed for 50 weeks, and then the peeling strength test is performed again;

[0058] The specific test results are shown in Table 1:

[0059] Table 1

[0060]

[0061] As can be seen from the test results in Table 1, the pressure-sensitive adhesive prepared by the present application has moderate initial adhesion, which meets the conventional initial adhesion positioning requirements, the holding adhesion reaches 120h without falling off, the initial peeling strength and the glass strength after heat cycle impact are excellent, and the bonding strength and stability to the polyester substrate are better.

[0062] In the description, references to "one embodiment," "an example," "certain examples" etc. mean that the particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the application. The appearances of an item in various examples or embodiments is not necessarily indicative of a frequency of occurrence in the various examples or embodiments. Moreover, descriptions of well-known methods associated are omitted so as not to obscure the disclosure.

[0063] The foregoing merely illustrates the principles of the application. Various modifications and adaptations will occur to those skilled in the art after consideration of the preceding description. All such modifications and adaptations employing the principles of the application are intended to be within the scope of the claims.

Claims

1. An acrylic pressure-sensitive adhesive for a polyester material, characterized by, The acrylic pressure sensitive adhesive is prepared by pre-polymerization of acrylic monomers and branched hydroxyl modified monomers, mixing with cross-linking agent, chelatable ultra-fine filler and film forming aid, and then drying, UV irradiation and cross-linking in sequence. The branched hydroxyl modified monomers are prepared by the following method: Step A1: mixing diethyl iminodiacetate and anhydrous tetrahydrofuran, drying the nitrogen atmosphere, cooling to 0-5℃, and adding acryloyl chloride and triethylamine while stirring for 8-10h to obtain acryloyl intermediate, wherein the amount ratio of diethyl iminodiacetate, acryloyl chloride, triethylamine and anhydrous tetrahydrofuran is 0.1mol:0.1mol:10-13mL:120-150mL; Step A2: mixing acryloyl intermediate, diethanolamine and anhydrous toluene, drying the nitrogen atmosphere, adding trimethylaluminum and mixing, pre-heating to 40-55℃ and stirring for 3-4h, and then continuously heating to 100-110℃ and refluxing for 1.5-2h to obtain branched hydroxyl modified monomers, wherein the amount ratio of acryloyl intermediate, diethanolamine, trimethylaluminum and anhydrous toluene is 0.1mol:0.2mol:0.6-0.9mL:80-100mL; The branched hydroxyl modified monomers are 15-22wt% of the acrylic monomers.

2. The acrylic pressure sensitive adhesive for a polyester material according to claim 1, characterized by, The acrylic monomers are compounded from acrylic acid, isooctyl acrylate and butyl acrylate in a molar ratio of 1:1.5-2:0.5-1.

3. The acrylic pressure sensitive adhesive for a polyester material according to claim 1, characterized by, The cross-linking agent is compounded from trimethylolpropane triacrylate and triethylene glycol dimethacrylate.

4. The acrylic pressure sensitive adhesive for a polyester material according to claim 1, characterized by, The chelatable ultra-fine filler is sub-micron calcium carbonate.

5. A method of preparing an acrylic pressure sensitive adhesive for a polyester material according to any one of claims 1 to 4, characterized in that, Specifically, Step S1: mixing acrylic monomers, branched hydroxyl modified monomers and ethyl acetate, heating to 70-80℃ under nitrogen protection, slowly adding azobisisobutyronitrile solution and stirring for 2.5-3.2h to obtain pre-polymer; Step S2: adding cross-linking agent, chelatable ultra-fine filler and film forming aid to the pre-polymer, mixing, vacuum degassing, coating on the surface of the carrier, drying by hot air, and then UV irradiation and cross-linking to obtain acrylic pressure sensitive adhesive.

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