Hot melt pressure sensitive adhesive and preparation method thereof

Abstract

The present invention belongs to the technical field of adhesives, and in particular to a hot-melt pressure-sensitive adhesive and a preparation method thereof, wherein the hot-melt pressure-sensitive adhesive is made of the following components in parts by weight: 100 parts of modified styrene-butadiene-styrene block copolymer, 10-20 parts of rosin pentaerythritol ester, 15-20 parts of polybutene, 0.5-1 parts of antioxidant, 1-5 parts of toughening agent, and 0.5-2 parts of filler; wherein the toughening agent is prepared by copolymerization of 10-20 parts of lactic acid, 1-5 parts of phenylalanine, and 5-8 parts of epoxy soybean oil. The present invention modifies styrene-butadiene-styrene block copolymer with lactic acid, activates modified epoxy soybean oil with lactic acid and phenylalanine, forms a winding system through the synergistic formation of modified styrene-butadiene-styrene block copolymer, toughening agent, rosin pentaerythritol ester, and polybutene, and finally forms a uniform system with antioxidant and filler, thereby improving the toughness and holding force of the hot-melt pressure-sensitive adhesive.

Description

Technical Field

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

[0002] Styrene-butadiene-styrene is a thermoplastic elastomer, referred to as SBS, which has good tensile strength and elasticity. It does not require plastication, mixing and vulcanization, saving energy and equipment investment. Its state changes reversibly with changes in temperature or solvent. It shows rubber elasticity at room temperature and can be plasticized and formed at high temperature. It has both the physical and mechanical properties of rubber and the processing properties of plastic. It is often used to manufacture sealing materials, tapes, adhesives, asphalt modifiers, etc.

[0003] Hot melt pressure sensitive adhesive is a type of adhesive with thermoplastic polymer as the base material. It has the dual characteristics of hot melt and pressure sensitivity. It is coated under molten conditions, and can be quickly bonded by applying slight pressure after hardening and crystallization. At the same time, it is easy to peel off and does not pollute the bonded surface. Styrene-butadiene-styrene is one of the most commonly used polymer elastomers in hot melt pressure sensitive adhesives. It has a large output and is most similar to rubber properties. Changing the type and content of additives when synthesizing hot melt pressure sensitive adhesives can change the adhesive properties of hot melt pressure sensitive adhesives.

[0004] Chinese patent CN104610892A discloses a hot melt pressure sensitive adhesive, comprising the following components in parts by weight: 5-8 parts of polystyrene-polyisoprene-polystyrene block copolymer, 5-8 parts of styrene-ethylene / butadiene-styrene copolymer, 5-10 parts of ethylene / vinyl acetate copolymer resin, 30-40 parts of softener, 0.5-1 part of antioxidant, 53-68 parts of tackifier, and 2-5 parts of polyisobutylene. In addition, a method for preparing a hot melt pressure sensitive adhesive is provided. The amount of tackifier added in this patent is relatively large, which easily causes the hot melt pressure sensitive adhesive to have too strong adhesion, and the colloid is prone to adhesion and melting, etc., causing the hot melt pressure sensitive adhesive to be unable to be pasted and removed as a whole during use, resulting in some colloid residues.

[0005] Chinese patent CN110157366A discloses a hot melt pressure-sensitive adhesive for environmentally friendly sanitary products, which is composed of the following components by weight: 40-70 parts of thermoplastic elastomer; 20-30 parts of tackifier; 5-8 parts of cross-linking agent; 1-3 parts of antioxidant; 10-15 parts of first coupling agent; 1-3 parts of other auxiliary agents; the tackifier is prepared from tackifying resin, reactive monomer, second coupling agent, and inorganic nanoparticles, the tackifying resin can be selected from aromatic series tackifying resin, the inorganic nano ion is nano alumina, and the thermoplastic elastomer is a combination of two or more of SBS, SIS, and SEBS. There are many additives in this patent, and the prepared hot melt pressure-sensitive adhesive has poor adhesive retention performance. Summary of the invention

[0006] In view of the above deficiencies in the prior art, the technical problem to be solved by the present invention is: to provide a hot-melt pressure-sensitive adhesive to solve the problems that the performance of the hot-melt pressure-sensitive adhesive is relatively low and the added substances cannot be fully combined to play a role, thereby improving the performance of the hot-melt pressure-sensitive adhesive; the present invention also provides a method for preparing a hot-melt pressure-sensitive adhesive.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] The hot-melt pressure-sensitive adhesive of the present invention is prepared from the following components in parts by weight: 100 parts of modified styrene-butadiene-styrene block copolymer, 10-20 parts of rosin pentaerythritol ester, 15-20 parts of polybutene, 0.5-1 parts of antioxidant, 1-5 parts of toughening agent, and 0.5-2 parts of filler; wherein the toughening agent is prepared by copolymerization of 10-20 parts of lactic acid, 1-5 parts of phenylalanine and 5-8 parts of epoxidized soybean oil.

[0009] in:

[0010] The preparation method of the modified styrene-butadiene-styrene block copolymer is as follows: under nitrogen protection, in the presence of cyclohexane and butyl lithium, styrene and lactic acid are first subjected to polymerization reaction, after the polymerization reaction is completed, diblock reaction is carried out with butadiene, and finally styrene is added to carry out triblock reaction to obtain a styrene-butadiene-styrene block copolymer.

[0011] The mass ratio of styrene and lactic acid used in the polymerization reaction is 10:(0.1-0.5); the polymerization reaction temperature is 60-70°C, and the polymerization reaction time is 0.1-0.5h.

[0012] The diblock reaction temperature is 70-80°C, the diblock reaction time is 0.5-1h; the mass ratio of styrene used in the polymerization reaction to butadiene used in the diblock reaction is 10:(5-6).

[0013] The triblock reaction temperature is 80-90°C, the triblock reaction time is 0.5-1h; the mass ratio of styrene used in the polymerization reaction to styrene used in the triblock reaction is 10:(15-20).

[0014] The copolymerization reaction temperature is 150-160° C., and the copolymerization reaction time is 1-2 hours.

[0015] The filler is nano silicon dioxide or nano calcium carbonate, and the filler particle size is 50-100nm; the antioxidant is antioxidant 1010.

[0016] The method for preparing the hot-melt pressure-sensitive adhesive comprises the following steps:

[0017] S1, copolymerizing lactic acid, phenylalanine and epoxidized soybean oil to obtain a toughening agent;

[0018] S2, cross-linking the styrene-butadiene-styrene block copolymer, the rosin pentaerythritol ester, the polybutene and the toughening agent;

[0019] S3. After the cross-linking reaction is completed, an antioxidant and a filler are added and mixed to obtain a hot-melt pressure-sensitive adhesive.

[0020] In the step S2, the cross-linking reaction temperature is 120-130° C., and the cross-linking reaction time is 1-2 hours.

[0021] In the step S3, the mixing reaction temperature is 140-160° C., and the mixing reaction time is 1-2 h.

[0022] The beneficial effects of the present invention are as follows:

[0023] (1) The hot-melt pressure-sensitive adhesive of the present invention adopts a modified styrene-butadiene-styrene block copolymer. The modified styrene-butadiene-styrene block copolymer is prepared by first grafting lactic acid onto styrene, then reacting with butadiene for a diblock reaction, and finally adding styrene for a triblock reaction. The present invention introduces lactic acid to modify the styrene-butadiene-styrene block copolymer. Since lactic acid has hydroxyl and carboxyl groups, the adhesion and cohesive force of the styrene-butadiene-styrene block copolymer are enhanced.

[0024] (2) The present invention innovatively adds a toughening agent to the hot-melt pressure-sensitive adhesive. The toughening agent is prepared by copolymerization of lactic acid, phenylalanine and epoxy soybean oil. The epoxy soybean oil is modified by lactic acid and phenylalanine. The hydroxyl, carboxyl and amino groups of lactic acid and phenylalanine react with the epoxy groups on the epoxy soybean oil. The carboxyl groups of lactic acid and phenylalanine form hydrogen bonds with the carboxyl groups on the epoxy soybean oil, thereby activating the modified epoxy soybean oil and improving adhesion and cohesion. The modified styrene-butadiene-styrene block copolymer also contains lactic acid, which ensures the compatibility of the modified styrene-butadiene-styrene block copolymer and the toughening agent.

[0025] (3) Lactic acid is grafted into the styrene-butadiene-styrene block copolymer of the present invention, and the hydroxyl group, carboxyl group and amino group in the toughening agent are attracted to each other through hydrogen bonds to form a cross-linking system. Polybutene and rosin pentaerythritol ester are added to form an entangled system with the cross-linking system. Finally, antioxidants and fillers are added to form a uniform system by bonding with the entangled system.

[0026] In summary, the present invention improves the toughness and adhesion of the hot-melt pressure-sensitive adhesive by modifying the styrene-butadiene-styrene block copolymer with lactic acid, activating and modifying the epoxy soybean oil with lactic acid and phenylalanine, synergistically forming a winding system through the modified styrene-butadiene-styrene block copolymer, a toughening agent, rosin pentaerythritol ester and polybutene, and finally forming a uniform system with an antioxidant and a filler. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 1 is a graph showing the annular initial adhesion data of Examples 1-4 and Comparative Examples 1-7 of the present invention;

[0028] Figure 2 180° peeling force data of Examples 1-4 and Comparative Examples 1-7 of the present invention;

[0029] Figure 3 is a graph showing the holding force data of Examples 1-4 and Comparative Examples 1-7 of the present invention;

[0030] Figure 4 It is a melt viscosity data chart of Examples 1-4 of the present invention and Comparative Examples 1-7. DETAILED DESCRIPTION

[0031] The present invention is specifically described and illustrated below in conjunction with embodiments.

[0032] Example 1

[0033] Preparation of modified styrene-butadiene-styrene block copolymers:

[0034] Under nitrogen protection, in the presence of 1000 ml of cyclohexane and 10 g of butyl lithium, 100 g of styrene and 5 g of lactic acid were added to carry out polymerization reaction at 65°C for 0.5 h. After the polymerization reaction was completed, 50 g of butadiene was added to carry out diblock reaction at 75°C for 1 h. Finally, 150 g of styrene was added to carry out triblock reaction at 80°C for 0.5 h to obtain a modified styrene-butadiene-styrene block copolymer. When the mass of the modified styrene-butadiene-styrene block copolymer is insufficient, the above steps can be repeated.

[0035] The preparation method of hot-melt pressure-sensitive adhesive comprises the following steps:

[0036] S1, 100g of lactic acid, 10g of phenylalanine and 80g of epoxidized soybean oil were mixed, and copolymerized at 160°C for 1h to obtain a toughening agent;

[0037] S2, cross-linking 1000 g of modified styrene-butadiene-styrene block copolymer, 200 g of rosin pentaerythritol ester, 200 g of polybutene and 50 g of toughening agent at 130° C. for 2 h;

[0038] S3, adding 10 g of antioxidant 1010 and 20 g of nano-silicon dioxide with a particle size of 100 nm, mixing and reacting at 150° C. for 2 h, to obtain a hot-melt pressure-sensitive adhesive.

[0039] Example 2

[0040] Preparation of modified styrene-butadiene-styrene block copolymers:

[0041] Under nitrogen protection, in the presence of 1000 ml of cyclohexane and 10 g of butyl lithium, 100 g of styrene and 1 g of lactic acid were added to carry out polymerization reaction at 70°C for 0.1 h. After the polymerization reaction was completed, 60 g of butadiene was added to carry out diblock reaction at 80°C for 0.5 h. Finally, 200 g of styrene was added to carry out triblock reaction at 90°C for 0.5 h to obtain a modified styrene-butadiene-styrene block copolymer. When the mass of the modified styrene-butadiene-styrene block copolymer is insufficient, the above steps can be repeated.

[0042] The preparation method of hot-melt pressure-sensitive adhesive comprises the following steps:

[0043] S1, 200g of lactic acid, 50g of phenylalanine and 50g of epoxidized soybean oil were mixed, and copolymerized at 150°C for 2h to obtain a toughening agent;

[0044] S2, cross-linking 1000 g of modified styrene-butadiene-styrene block copolymer, 100 g of rosin pentaerythritol ester, 150 g of polybutene and 10 g of toughening agent at 130° C. for 1 h;

[0045] S3, adding 5 g of antioxidant 1010 and 10 g of nano-silicon dioxide with a particle size of 80 nm, mixing and reacting at 160° C. for 1 h, to obtain a hot-melt pressure-sensitive adhesive.

[0046] Example 3

[0047] Preparation of modified styrene-butadiene-styrene block copolymers:

[0048] Under nitrogen protection, in the presence of 1000 ml of cyclohexane and 10 g of butyl lithium, 100 g of styrene and 3 g of lactic acid were added to carry out polymerization reaction at 60°C for 0.25 h. After the polymerization reaction was completed, 50 g of butadiene was added to carry out diblock reaction at 70°C for 0.75 h. Finally, 180 g of styrene was added to carry out triblock reaction at 85°C for 1 h to obtain a modified styrene-butadiene-styrene block copolymer. When the mass of the modified styrene-butadiene-styrene block copolymer is insufficient, the above steps can be repeated.

[0049] The preparation method of hot-melt pressure-sensitive adhesive comprises the following steps:

[0050] S1, 150g of lactic acid, 30g of phenylalanine and 60g of epoxidized soybean oil were mixed, and copolymerized at 155°C for 1.5h to obtain a toughening agent;

[0051] S2, cross-linking 1000 g of modified styrene-butadiene-styrene block copolymer, 150 g of rosin pentaerythritol ester, 170 g of polybutene, and 30 g of toughening agent at 125° C. for 1.5 h;

[0052] S3, adding 7.5 g of antioxidant 1010 and 5 g of nano calcium carbonate with a particle size of 50 nm, mixing and reacting at 140° C. for 2 h, to obtain a hot melt pressure-sensitive adhesive.

[0053] Example 4

[0054] Preparation of modified styrene-butadiene-styrene block copolymers:

[0055] Under nitrogen protection, in the presence of 1000 ml of cyclohexane and 10 g of butyl lithium, 100 g of styrene and 5 g of lactic acid were added to carry out polymerization reaction at 70°C for 0.1 h. After the polymerization reaction was completed, 60 g of butadiene was added to carry out diblock reaction at 80°C for 0.5 h. Finally, 200 g of styrene was added to carry out triblock reaction at 90°C for 0.75 h to obtain a modified styrene-butadiene-styrene block copolymer. When the mass of the modified styrene-butadiene-styrene block copolymer is insufficient, the above steps can be repeated.

[0056] The preparation method of hot-melt pressure-sensitive adhesive comprises the following steps:

[0057] S1, 100g of lactic acid, 50g of phenylalanine and 80g of epoxidized soybean oil were mixed, and copolymerized at 160°C for 1.75h to obtain a toughening agent;

[0058] S2, cross-linking 1000 g of modified styrene-butadiene-styrene block copolymer, 200 g of rosin pentaerythritol ester, 180 g of polybutene and 50 g of toughening agent at 120° C. for 2 h;

[0059] S3. Add 10 g of antioxidant 1010 and 15 g of nano calcium carbonate with a particle size of 70 nm, and mix and react at 150° C. for 1.5 h to obtain a hot-melt pressure-sensitive adhesive.

[0060] Comparative Example 1

[0061] In the process of preparing the modified styrene-butadiene-styrene block copolymer, no lactic acid was added, and the remaining operations were the same as in Example 1.

[0062] Comparative Example 2

[0063] In step S1, no lactic acid is added when preparing the toughening agent, and the remaining operations are the same as in Example 1.

[0064] Comparative Example 3

[0065] In step S1, phenylalanine is not added when preparing the toughening agent, and the remaining operations are the same as in Example 1.

[0066] Comparative Example 4

[0067] In step S1, no epoxy soybean oil is added when preparing the toughening agent, and the remaining operations are the same as in Example 1.

[0068] Comparative Example 5

[0069] In step S1, only lactic acid is added when preparing the toughening agent, and the remaining operations are the same as in Example 1.

[0070] Comparative Example 6

[0071] In step S1, only phenylalanine is added when preparing the toughening agent, and the remaining operations are the same as in Example 1.

[0072] Comparative Example 7

[0073] In step S1, only epoxy soybean oil is added when preparing the toughening agent, and the rest of the operations are the same as in Example 1.

[0074] The hot melt pressure sensitive adhesives prepared in Examples 1-4 and Comparative Examples 1-7 were subjected to performance tests. The test results are shown in Table 1 and Figure 1-4 shown.

[0075]

[0076] From Table 1 and Figure 1-4 It can be seen that the hot-melt pressure-sensitive adhesive prepared by the present invention improves the adhesive properties of the hot-melt pressure-sensitive adhesive by adding lactic acid in advance and adjusting the toughening agent formula, and the styrene-butadiene-styrene block copolymer is modified by adding lactic acid. Since lactic acid has hydroxyl and carboxyl groups, the adhesion and bonding force of the styrene-butadiene-styrene block copolymer are enhanced, and the interaction between the raw materials is promoted, thereby improving the preparation efficiency and product quality of the styrene-butadiene-styrene block copolymer.

[0077] In Comparative Example 1, lactic acid is not added when preparing the modified styrene-butadiene-styrene block copolymer, resulting in poor effect of the hot-melt pressure-sensitive adhesive finally prepared; the toughening agent added when preparing the hot-melt pressure-sensitive adhesive is composed of three substances that promote each other to form a network structure, which can be evenly distributed in the hot-melt pressure-sensitive adhesive to change the overall bonding effect of the hot-melt pressure-sensitive adhesive. In Comparative Examples 2-7, only one or two of lactic acid, phenylalanine or epoxy soybean oil are added, which cannot form a network structure and cannot improve the overall bonding effect of the hot-melt pressure-sensitive adhesive. Therefore, compared with Example 1, the use effects are all poor.

Claims

1. A hot melt pressure sensitive adhesive, characterized in that: The invention is prepared from the following components in parts by weight: 100 parts of modified styrene-butadiene-styrene block copolymer, 10-20 parts of rosin pentaerythritol ester, 15-20 parts of polybutene, 0.5-1 parts of antioxidant, 1-5 parts of toughening agent, and 0.5-2 parts of filler; wherein the toughening agent is prepared by copolymerization of 10-20 parts of lactic acid, 1-5 parts of phenylalanine and 5-8 parts of epoxidized soybean oil; The preparation method of the modified styrene-butadiene-styrene block copolymer is as follows: under nitrogen protection, in the presence of cyclohexane and butyl lithium, styrene and lactic acid are firstly polymerized, and after the polymerization reaction is completed, they are reacted with butadiene for diblock reaction, and finally styrene is added for triblock reaction to obtain the modified styrene-butadiene-styrene block copolymer; The mass ratio of styrene and lactic acid used in the polymerization reaction is 10: (0.1-0.5); The mass ratio of styrene used in the polymerization reaction to butadiene used in the diblock reaction is 10:(5-6); The mass ratio of styrene used in the polymerization reaction to styrene used in the triblock reaction is 10:(15-20).

2. The hot melt pressure sensitive adhesive according to claim 1, characterized in that: The polymerization reaction temperature is 60-70°C, and the polymerization reaction time is 0.1-0.5h.

3. The hot melt pressure sensitive adhesive according to claim 1, characterized in that: The diblock reaction temperature is 70-80°C, and the diblock reaction time is 0.5-1h.

4. The hot melt pressure sensitive adhesive according to claim 1, characterized in that: The triblock reaction temperature is 80-90°C, and the triblock reaction time is 0.5-1h.

5. The hot melt pressure sensitive adhesive according to claim 1, characterized in that: The copolymerization reaction temperature is 150-160°C, and the copolymerization reaction time is 1-2h.

6. The hot melt pressure sensitive adhesive according to claim 1, characterized in that: The filler is nano silicon dioxide or nano calcium carbonate, and the particle size of the filler is 50-100nm; the antioxidant is antioxidant 1010.

7. A method for preparing the hot melt pressure sensitive adhesive according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, copolymerizing lactic acid, phenylalanine and epoxidized soybean oil to obtain a toughening agent; S2, cross-linking the modified styrene-butadiene-styrene block copolymer, rosin pentaerythritol ester, polybutene and toughening agent; S3. After the cross-linking reaction is completed, an antioxidant and a filler are added and mixed to obtain a hot-melt pressure-sensitive adhesive.

8. The method for preparing a hot melt pressure sensitive adhesive according to claim 7, characterized in that: In step S2, the cross-linking reaction temperature is 120-130° C., and the cross-linking reaction time is 1-2 h.

9. The method for preparing a hot-melt pressure-sensitive adhesive according to claim 7, characterized in that: In step S3, the mixing reaction temperature is 140-160° C., and the mixing reaction time is 1-2 h.

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