Pressure-sensitive adhesive as well as preparation method and application thereof

Abstract

The invention discloses a pressure-sensitive adhesive as well as a preparation method and application thereof. The method comprises the following steps: firstly, preparing an acrylate base copolymer with an active squaric acid ester side group through a copolymerization reaction; and then, carrying out efficient post-polymerization modification reaction on the basic copolymer and various primary amine compounds under the action of a catalyst. According to the reaction, diversified functional groups are modularly introduced into a polymer side chain, and meanwhile, a square amide structure with a strong hydrogen-bond interaction is generated in situ. The adhesive property of the pressure-sensitive adhesive can be conveniently regulated and controlled by replacing the types of the primary amine compounds, and meanwhile, the cohesion strength of the material is effectively enhanced by a squaramide hydrogen bond network, so that the cooperative regulation and control of the adhesion property and the cohesion property are realized. The method is mild in condition and high in universality, and a novel and effective way is provided for design and preparation of the high-performance functional pressure-sensitive adhesive.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and specifically relates to a functional acrylic pressure-sensitive adhesive, particularly a pressure-sensitive adhesive with tunable performance prepared by a modular post-polymerization modification strategy, its preparation method, and its application. Background Technology

[0002] Pressure-sensitive adhesives (PSAs) are a class of polymeric materials that achieve rapid bonding under slight pressure and are widely used in electronics, medical, packaging, and labeling industries. Acrylic PSAs are particularly favored due to their excellent weather resistance and transparency. However, traditional methods for preparing functional PSAs often rely on the direct copolymerization of functional monomers and host monomers. This method has several limitations: for example, the types of functional monomers are limited, their synthesis is difficult, or side reactions are easily triggered during polymerization, leading to difficulty in precisely controlling the performance of the final product and poor batch-to-batch stability.

[0003] To achieve precise control over the performance of PSAs, post-polymerization modification strategies have emerged. These strategies allow the introduction of desired functional groups onto a pre-synthesized polymer backbone, enabling the systematic study of the impact of side-chain functional groups on the macroscopic properties of the material while maintaining the basic structure of the polymer backbone and, more importantly, the molecular weight of the backbone polymer. Although various post-modification chemistry methods have been reported, developing novel, modular modification platforms based on mild and efficient reactions, especially strategies capable of simultaneously introducing functional groups and strong physical crosslinking points, remains crucial for developing high-performance PSAs.

[0004] Squaramide structural units have shown great potential in enhancing the cohesive strength of materials due to their ability to form strong double hydrogen bond networks. However, there are few reports on how to combine quaramide chemistry with the modular functional design of PSAs. Summary of the Invention

[0005] This invention provides a pressure-sensitive adhesive, its preparation method, and its application, which can synergistically regulate adhesion and cohesion properties through a modular strategy. This solves the problems of difficult performance control and limited functionalization pathways in the preparation methods of functional pressure-sensitive adhesives in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a pressure-sensitive adhesive includes the following steps: S1. A copolymerization reaction is carried out between an acrylate monomer containing squartz acid ester groups and one or more acrylate main monomers to obtain a basic copolymer with active squartz acid ester side groups. S2. The base copolymer is subjected to a nucleophilic substitution reaction with one or more primary amine compounds in the presence of an organic base catalyst, so that the primary amine compounds are grafted onto the side chains of the base copolymer and in situ generated into square amide structural units, thereby obtaining the pressure-sensitive adhesive.

[0007] As a preferred embodiment, the acrylate monomer containing squaric acid ester group is a monosubstituted product of 2-aminoethyl methacrylate hydrochloride and diethyl squaric acid ester; The acrylate main monomer is selected from one or more of methyl acrylate, ethyl acrylate, n-butyl acrylate, isooctyl acrylate, and 2-ethylhexyl acrylate.

[0008] As a preferred embodiment, the primary amine compound is an alcoholamine compound; Preferably, the alkanolamine compound is selected from one or more of the following: ethanolamine, 3-amino-1-propanol, 4-amino-1-butanol, 5-amino-1-pentanol, 6-amino-1-hexanol, 2-amino-2-methyl-1-propanol, 2-amino-1-butanol, 3-amino-1,2-propanediol, serine, threonine, glucosamine, and galactosamine.

[0009] As a preferred embodiment, the primary amine compound is an aliphatic amine compound; Preferably, the fatty amine compound is selected from one or more of the following: methylamine, ethylamine, propylamine, n-butylamine, isobutylamine, n-hexylamine, cyclohexylamine, n-octylamine, n-dodecylamine, and n-octadecylamine.

[0010] As a preferred embodiment, the primary amine compound is an aromatic amine compound; Preferably, the aromatic amine compound is selected from one or more of aniline, benzylamine, phenethylamine, p-methoxyaniline, and furfurylamine.

[0011] As a preferred embodiment, the primary amine compound is an amine compound containing other functional groups; Preferably, the other functional groups are selected from carboxyl, ester, epoxy, ether, amide, morpholine ring, and pyridine ring; Preferably, the amine compound containing other functional groups is selected from one or more of the following: glycine, alanine, 6-aminohexanoic acid, glycine methyl ester, glycidylamine, 2-methoxyethylamine, 4-(2-aminoethyl)morpholine, aminoethylpiperazine, and histamine.

[0012] As a preferred embodiment, the organic base catalyst is a non-nucleophilic organic base; The non-nucleophilic organic base is selected from one or more of the following: triethylamine, diisopropylethylamine, N-methylmorpholine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,5,7-trizabicyclo[4.4.0]dec-5-ene (TBD), and proton sponges.

[0013] A pressure-sensitive adhesive prepared by the method described above.

[0014] A pressure-sensitive adhesive structure includes a polymer backbone composed of acrylate monomers and a side group -R connected to the backbone via a square amide structure, wherein the -R group is derived from the primary amine compound R-NH2; The R-NH2 is selected from one or more of alcohol amines, aliphatic amines, aromatic amines, or amines containing other functional groups.

[0015] An application of the pressure-sensitive adhesive prepared by the preparation method described above includes products containing the pressure-sensitive adhesive, such as tapes.

[0016] As a preferred method, the obtained pressure-sensitive adhesive solution was coated onto a PET substrate with a thickness of approximately 20 μm, cured at 70°C for 20 min, and then made into an adhesive tape. Peel strength at 90° and 180°, static shear strength, and DSC tests were performed. The results showed that, compared to the unmodified sample, the shear time of the modified pressure-sensitive adhesive increased from 360 minutes to 3120 minutes, and the cohesive strength was significantly improved.

[0017] A method for preparing a pressure-sensitive adhesive includes the following steps: S1. Synthesis of acrylate monomers containing squaric acid ester groups: 2-aminoethyl methacrylate hydrochloride was monosubstituted with diethyl squaric acid to synthesize the monosubstituted squaric acid ester group acrylate monomer SqEAM. S2. Preparation of basic copolymer: An acrylate monomer containing squaric acid ester groups is copolymerized with one or more acrylate main monomers to obtain a basic copolymer with active squaric acid ester side groups. S3. Post-polymerization modification: The base copolymer is subjected to a nucleophilic substitution reaction with one or more monofunctional primary amines or bifunctional primary amine compounds in the presence of an organic base catalyst, so that the primary amine compound is grafted onto the side chain of the base copolymer and a square amide structural unit is generated in situ to obtain the pressure-sensitive adhesive.

[0018] The present invention also provides a pressure-sensitive adhesive prepared by the above method, and a pressure-sensitive adhesive product containing the pressure-sensitive adhesive, such as an adhesive tape.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. Modularity and versatility: This invention provides a universal modular modification platform. By changing different primary amine compounds, diverse functional groups can be conveniently introduced onto the same polymer backbone to achieve "customized" performance design.

[0020] 2. Synergistic regulation of performance: While introducing functional side chains, the post-modification reaction generates in-situ square amide groups that serve as physical crosslinking points through their strong hydrogen bond network, significantly enhancing the cohesive strength and creep resistance of the pressure-sensitive adhesive, thus achieving synergistic regulation of adhesion and cohesion.

[0021] 3. Mild and efficient reaction conditions: The post-polymerization modification reaction conditions are mild and efficient, with little impact on the polymer backbone, making it easy to industrialize.

[0022] 4. Wide range of adjustable performance: By adjusting the proportion of ester monomers in the base copolymer and selecting primary amine compounds with different structures and functions, the final performance of the pressure-sensitive adhesive can be adjusted over a wide range to meet the needs of different application scenarios. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the basic copolymer modified with various functional groups in this invention; Figure 2 The basic copolymer P(BA) in this invention 100 -co-SqEAM5) 1 H NMR; Figure 3 The basic copolymer P(BA) in this invention 100 -co-SqEAM5) modified with propylamine 1 H NMR. Detailed Implementation

[0024] The present invention will be further described below with reference to embodiments.

[0025] Example 1: P(BA) 100 Preparation of -co-SqEAM5 and post-modification with propylamine (1) Synthesis of monomer SqEAM: 3,4-diethoxy-3-cyclobutene-1,2-dione and 2-aminoethyl methacrylate hydrochloride were mixed in ethanol, and triethylamine was added as a catalyst. The mixture was reacted at room temperature for 12 hours. After the reaction, the solvent was removed by rotary evaporation, and the target monomer SqEAM was obtained by column chromatography. Its structure was determined by... 1 H NMR, 13 CNMR and HR-MS confirmed.

[0026] (2) Basic copolymer P(BA) 100Synthesis of -co-SqEAM5): Butyl acrylate (BA) and monomer SqEAM (molar ratio 100:5) were dissolved in ethyl acetate (EA), and initiator AIBN was added. The reaction was carried out at 70°C for 12 hours. The actual ratio of BA to SqEAM in the polymer could be accurately obtained by ¹H NMR quantitative analysis.

[0027] (3) Post-propylamine modification: In P(BA 100 In a mixture of -co-SqEAM5, excess propylamine and triethylamine catalyst were added, and the mixture was stirred at 70°C for 12 hours to obtain a propylamine-modified pressure-sensitive adhesive.

[0028] (4) Performance testing: The obtained pressure-sensitive adhesive solution was coated onto a PET substrate to a thickness of approximately 20 μm and cured at 70°C for 20 min to form an adhesive tape. The 180° peel strength and static shear strength (0.5 kg load, 25 mm × 25 mm) of the stainless steel sheet were tested. The test results are summarized in Table 1.

[0029] Examples 2-5: Post-modification of alkanolamine compounds The same process steps as in Example 1 (3) were used, except that propylamine was replaced with equimolar amounts of different alcoholic amine compounds, namely: ethanolamine (Example 2), 3-amino-1,2-propanediol (Example 3), 4-amino-1-butanol (Example 4), and 2-amino-2-methyl-1-propanol (Example 5). Adhesion properties were tested according to the method in Example 1, and the specific data are shown in Table 1.

[0030] Examples 6-9: Post-modification of aliphatic amine compounds The same process steps as in Example 1 (3) were used, except that propylamine was replaced with equimolar amounts of different aliphatic amine compounds, namely: n-butylamine (Example 6), cyclohexylamine (Example 7), n-octylamine (Example 8), and n-dodecylamine (Example 9). After the introduction of aliphatic amines with different chain lengths, the flexibility and entanglement of the polymer side chains changed, thereby achieving the adjustment of the peel strength and cohesive strength of the pressure-sensitive adhesive. Specific data are shown in Table 1.

[0031] Examples 10-12: Post-modification of aromatic amine compounds The same process steps as in Example 1 (3) were used, except that propylamine was replaced with equimolar amounts of different aromatic amine compounds, namely: benzylamine (Example 10), phenylethylamine (Example 11), and furfurylamine (Example 12). The introduction of aromatic rings endowed the side chains with strong rigidity and π-π stacking effect, which significantly improved the heat shear resistance of the material. Specific data are shown in Table 1.

[0032] Examples 13-14: Post-modification of amine compounds containing other functional groups The same process steps as in Example 1 (3) were used, except that propylamine was replaced with equimolar amounts of amine compounds containing other functional groups, namely: glycine methyl ester (Example 13, containing an ester group) and 4-(2-aminoethyl)morpholine (Example 14, containing a morpholine ring). The results showed that the method of the present invention has good universality and can be compatible with a variety of functional groups. Specific performance data are shown in Table 1.

[0033] Example 15: Application of different catalysts Using a similar procedure to Example 1 (3), replacing the catalyst triethylamine with DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) or TBD (1,5,7-trizabicyclo[4.4.0]dec-5-ene) can also efficiently catalyze the post-modification reaction and obtain a pressure-sensitive adhesive with excellent performance.

[0034] Comparative Example 1: Unmodified basic copolymer Use the P(BA) prepared in step (2) directly. 100 The tape was prepared from a solution of a α-co-SqEAM5-based copolymer without any post-amine modification. As a blank control group, its performance was tested and is shown in Table 1.

[0035] Specifically, the basic copolymer P(BA) 100 Synthesis of -co-SqEAM5: Butyl acrylate (BA) and monomer SqEAM (molar ratio 100:5) were dissolved in ethyl acetate (EA), and initiator AIBN was added. The mixture was reacted at 70°C for 12 hours.

[0036] Table 1. Comparison of performance data of pressure-sensitive adhesives modified with different primary amine compounds The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a pressure-sensitive adhesive, characterized in that, Includes the following steps: S1. A copolymerization reaction is carried out between an acrylate monomer containing squartz acid ester groups and one or more acrylate main monomers to obtain a basic copolymer with active squartz acid ester side groups. S2. The base copolymer is subjected to a nucleophilic substitution reaction with one or more primary amine compounds in the presence of an organic base catalyst, so that the primary amine compounds are grafted onto the side chains of the base copolymer and in situ generated into square amide structural units, thereby obtaining the pressure-sensitive adhesive.

2. The method for preparing pressure-sensitive adhesive according to claim 1, characterized in that, The acrylate monomer containing squaric acid ester group is a monosubstituted product of 2-aminoethyl methacrylate hydrochloride and diethyl squaric acid ester. The acrylate main monomer is selected from one or more of methyl acrylate, ethyl acrylate, n-butyl acrylate, isooctyl acrylate, and 2-ethylhexyl acrylate.

3. The method for preparing pressure-sensitive adhesive according to claim 1, characterized in that, The primary amine compound is an alcohol amine compound; The alkanolamine compound is selected from one or more of the following: ethanolamine, 3-amino-1-propanol, 4-amino-1-butanol, 5-amino-1-pentanol, 6-amino-1-hexanol, 2-amino-2-methyl-1-propanol, 2-amino-1-butanol, 3-amino-1,2-propanediol, serine, threonine, glucosamine, and galactosamine.

4. The method for preparing pressure-sensitive adhesive according to claim 1, characterized in that, The primary amine compound is an aliphatic amine compound; The fatty amine compound is selected from one or more of the following: methylamine, ethylamine, propylamine, n-butylamine, isobutylamine, n-hexylamine, cyclohexylamine, n-octylamine, n-dodecylamine, and n-octadecylamine.

5. The method for preparing pressure-sensitive adhesive according to claim 1, characterized in that, The primary amine compound is an aromatic amine compound; The aromatic amine compound is selected from one or more of the following: aniline, benzylamine, phenethylamine, p-methoxyaniline, and furfurylamine.

6. The method for preparing pressure-sensitive adhesive according to claim 1, characterized in that, The primary amine compound is an amine compound containing other functional groups; The other functional groups are selected from carboxyl, ester, epoxy, ether, amide, morpholine ring, and pyridine ring; The amine compound containing other functional groups is preferably selected from one or more of the following: glycine, alanine, 6-aminohexanoic acid, glycine methyl ester, glycidylamine, 2-methoxyethylamine, 4-(2-aminoethyl)morpholine, aminoethylpiperazine, and histamine.

7. The method for preparing pressure-sensitive adhesive according to claim 1, characterized in that, The organic base catalyst is a non-nucleophilic organic base; The non-nucleophilic organic base is selected from one or more of the following: triethylamine, diisopropylethylamine, N-methylmorpholine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,5,7-trizabicyclo[4.4.0]dec-5-ene (TBD), and proton sponges.

8. A pressure-sensitive adhesive prepared by the method of any one of claims 1-7.

9. A pressure-sensitive adhesive, characterized in that, Its structure includes a polymer backbone composed of acrylate monomers and a side group -R connected to the backbone via a square amide structure, wherein the -R group is derived from the primary amine compound R-NH2; The R-NH2 is selected from one or more of alcohol amines, aliphatic amines, aromatic amines, or amines containing other functional groups.

10. The application of the pressure-sensitive adhesive prepared by any one of the preparation methods according to claims 1-7, characterized in that, Articles containing the pressure-sensitive adhesive.

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