KR102315705B1 - Manufacturing method of adhesive composition with improved heat-resistance - Google Patents

Abstract

The present invention relates to a method for manufacturing an acrylic adhesive having improved heat resistance while maintaining the same level of adhesion as a conventional acrylic adhesive by including a step of mixing a tacky monomer and a radical initiator to a styrene-ethylene-butylene-styrene (SEBS) polymer grafted with maleic anhydride to graft the tacky monomer onto the SEBS polymer.

Description

Manufacturing method of acrylic adhesive with improved heat resistance. {MANUFACTURING METHOD OF ADHESIVE COMPOSITION WITH IMPROVED HEAT-RESISTANCE}

The present invention relates to a method for producing an acrylic pressure-sensitive adhesive having improved heat resistance, and more particularly, to a method for producing an acrylic pressure-sensitive adhesive having improved heat resistance by grafting a monomer to a polymer chain.

Polyacrylate is a polymer made by reaction of acrylic acid ester or acrylic acid having an acrylic functional group. The polyacrylate can be used in a variety of plastics, such as rubber and adhesive, depending on the ratio of the hard monomer to the soft monomer, and is basically used as an adhesive containing a monomer having a low glass transition temperature because of its adhesiveness.

The polyacrylate is a saturated polymer without double bonds in the molecule, has excellent resistance to oxidation, has excellent weather resistance, is basically excellent in heat resistance, is transparent, and has excellent adhesion to metal. It is very useful for adhesion.

Adhesion means a temporary bonding state in which there is no change in components unless two or more materials are artificially moved by an external force. Therefore, the pressure-sensitive adhesive can be adhered without using water, solvent, heat, etc., even by applying a slight pressure at room temperature. That is, the pressure-sensitive adhesive is a viscoelastic material that is in a solid state but exhibits viscoelastic behavior. Since it has cohesive force and elasticity by itself, it can adhere strongly, and at the same time, it should not leave any residue when removed from the adherend. It should be possible

The main components of the acrylic pressure-sensitive adhesive are alkyl acrylate and methacrylate having 4 to 17 carbons, which have a low glass transition temperature and can obtain a soft and cohesive polymer. Mainly, 2-ethylhexyl acrylate and butyl acrylate are used, and homopolymers are used as copolymers. Monomers with functional groups are sometimes used to impart wettability and crosslinking points. In general, the composition of the acrylic pressure-sensitive adhesive is 50 to 90% of the main monomer, 10 to 14% of the sub-monomer, and 2 to 20% of the functional monomer. Since the monomers used in the pressure-sensitive adhesive have their own unique glass transition temperature, and their physical properties vary greatly depending on the ratio and type of each monomer, it is necessary to select a monomer suitable for the purpose.

One of the characteristics of the recently developed foldable display is that the screen can be enlarged by expanding the screen when necessary. In other words, while it has the advantage of having a large screen, the possibility of heat generation may increase as well, and the foldable display consumes more power and generates more heat than a general display even if it is used for the same amount of time. In addition, in addition to the development direction of the smartphone, the curved or bent shape is also set as the development direction, so the key parts in the smartphone are also inevitably taking the shape of light, thin, and short. In this case, the importance of attachment in which each of the core parts can be strongly connected and fixed without falling off even at high temperatures is further increased.

Therefore, it is absolutely necessary to develop an acrylic pressure-sensitive adhesive having higher heat resistance while maintaining the adhesive strength of existing materials.

Conventional acrylic pressure-sensitive adhesives have excellent adhesion at room temperature, but there is a limit to adhesion under special circumstances, low or high temperatures. In order to compensate for this, the polymerization of the present invention starts from a polymer already polymerized differently from the conventional polymerization method starting from a monomer. It is necessary to select a polymer that has a high basic glass transition temperature and is compatible with monomers that can impart adhesiveness.

For example, Korean Patent Application Laid-Open No. 10-2016-0142286 discloses that the temperature sensitivity is improved through a branched crystalline polymer composed of a graft copolymer of a crystalline macromonomer and an amorphous monomer. It is expected to be able to manufacture an acrylic adhesive with improved heat resistance while maintaining adhesive properties.

Republic of Korea Patent Publication No. 10-2016-0142286

The present invention has been devised in view of the prior art as described above, and includes a step of grafting by reacting a monomer capable of imparting adhesiveness to a polymer with a radical initiator in the manufacturing process of the acrylic pressure-sensitive adhesive, thereby manufacturing an acrylic pressure-sensitive adhesive with improved heat resistance The purpose is to provide a way to do it.

The method for producing an acrylic pressure-sensitive adhesive with improved heat resistance of the present invention for solving the above problems is a styrene-ethylene-butylene-styrene (SEBS) polymer grafted with maleic anhydride by mixing an adhesive monomer and a radical initiator, and the adhesive monomer is characterized in that it comprises the step of grafting to the SEBS polymer.

In this case, the adhesive monomer is glycidyl methacrylate, 2-ethylhexyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate (methyl methacrylate), beta-carboxyl ethyl acrylate (β-carboxyl ethyl acrylate), may be any one or more selected from acrylic acid (acrylic acid), the radical initiator is azobisisobutyronitrile (azobisisobutyronitrile), Di-(2,4-dichlorobenzoyl) peroxide (di-(2,4-dichlorobenzoyl)-peroxide), dibenzoyl peroxide, di-t-butylperoxybenzoate (di(t-butyl) peroxybenzoate), dicumyl peroxide, di-t-butylperoxide, 1,1-di-(t-butylperoxy)-3,3,5-trimethylcyclohexane (1,1-di-(t-butylperoxy)-3,3,5-trimethylcyclohexane), di-(t-butylperoxyisopropyl)benzene (di-(t-butylperoxyisopropyl)benzene, PK-14), t - From t-butylcumylperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexane (2,5-dimethyl-2,5di(t-butylperoxy)-hexane) It may be any one or more selected.

In addition, the maleic anhydride-grafted SEBS polymer may be included in an amount of 25 to 60 parts by weight based on 100 parts by weight of the acrylic adhesive.

In addition, the radical initiator may be included in an amount of 0.2 parts by weight based on 100 parts by weight of the acrylic adhesive.

The manufacturing method of the acrylic adhesive according to the present invention includes a step of grafting by reacting a monomer capable of imparting adhesiveness to a polymer with a radical initiator during the manufacturing process of the acrylic adhesive, thereby exhibiting the same level of adhesiveness as that of the conventional acrylic adhesive. It shows the effect of improving heat resistance.

1 is a cross-sectional view of a high heat-resistant adhesive tape to which the acrylic adhesive of the present invention is applied.

Hereinafter, the present invention will be described in more detail. The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that there is.

The method for producing an acrylic pressure-sensitive adhesive with improved heat resistance of the present invention comprises mixing a styrene-ethylene-butylene-styrene (SEBS) polymer grafted with maleic anhydride and a tacky monomer and a radical initiator, so that the tacky monomer is grafted onto the SEBS polymer. includes steps.

The SEBS polymer to which maleic anhydride is grafted has compatibility with the acrylic monomer by grafting maleic anhydride to the SEBS polymer.

Monomers used to impart adhesiveness usually lack heat resistance due to their low glass transition temperature. It is possible to improve heat resistance while maintaining the adhesiveness of the acrylic adhesive.

The compatible adhesive monomer is glycidyl methacrylate, 2-ethylhexyl acrylate, ethyl acrylate, butyl acrylate, methyl meta It may be any one or more selected from acrylate (methyl methacrylate), beta-carboxyl ethyl acrylate (β-carboxyl ethyl acrylate), and acrylic acid (acrylic acid). It is preferable to use double glycidyl methacrylate, because the epoxy group contained in glycidyl methacrylate has good reactivity.

In addition, it is preferable that the acrylic pressure-sensitive adhesive contains 0.2% by weight of azobisbutyronitrile based on the total weight of the pressure-sensitive adhesive. When azobisbutyronitrile is 0.2 wt% or more, it is helpful in terms of improved heat resistance, but the transparency of the pressure-sensitive adhesive is lowered. Formation interferes with the adhesive properties.

The pressure-sensitive adhesive of the present invention may be prepared using a four-necked flask. That is, glycidyl methacrylate is first reacted with the maleic anhydride grafted SEBS polymer. Thereafter, 2-ethylhexyl acrylate, ethyl acrylate, beta-carboxyl ethyl acrylate, and acrylic acid were mixed with the mixed solution and then heated to 90° C. to polymerize for 1 hour. Specifically, 35 to 55 wt% of SEBS grafted with maleic anhydride, 2.8 wt% of glycidyl methacrylate, 20 to 30 wt% of 2-ethylhexyl acrylate, 13 to 20 wt% of ethyl acrylate, beta-carryl It is preferable to perform the reaction by mixing 3 to 7% by weight of carboxylethyl acrylate and 3 to 7% by weight of acrylic acid. When the amount of maleic anhydride grafted SBES is 35 wt% or less, there is no problem in the synthesis, but the effect of increasing heat resistance is reduced.

In addition, the radical initiator is azobisisobutyronitrile (azobisisobutyronitrile), di- (2,4-dichlorobenzoyl) peroxide (di- (2,4-dichlorobenzoyl) -peroxide), dibenzoyl peroxide (dibenzoyl peroxide) , di-t-butylperoxybenzoate (di(t-butyl peroxybenzoate)), dicumyl peroxide (dicumyl peroxide), di-t-butylperoxide (di-t-butylperoxide), 1,1-di-( t-Butylperoxy)-3,3,5-trimethylcyclohexane (1,1-di-(t-butylperoxy)-3,3,5-trimethylcyclohexane), di-(t-butylperoxyisopropyl)benzene (di-(t-butylperoxyisopropyl)benzene, PK-14), t-butylcumylperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexane (2, It may be any one or more selected from 5-dimethyl-2,5di(t-butylperoxy)-hexane). Of these, it is preferable to use azobisisobutyronitrile, and the azobisisobutyronitrile is mixed so as to be 0.2 wt% based on the total mixed solution, but this is divided into two and added. In the case of divisional addition, after 2 hours have elapsed after adding the first mixed solution, the second mixed solution is added and reacted for 1 hour. Through this, the acrylic pressure-sensitive adhesive of the present invention can be prepared.

The acrylic pressure-sensitive adhesive of the present invention prepared in this way can improve heat resistance under the influence of the SEBS polymer grafted with maleic anhydride.

The effects of the manufacturing method of the present invention will be described with reference to the following examples.

Example 1

In a 4-neck flask, 80 g of SEBS-g-MA having a maleic anhydride content of 2%, 4.2 g of glycidyl methacrylate, and 320 g of toluene were placed, and then heated to 70° C. and stirred for 30 minutes. Next, 35 g of 2-ethylhexyl acrylate monomer (2-EHAM), 20 g of ethyl acrylate monomer (EAM), 4 g of beta-carboxylethyl acrylate (β-CEA), 4 g of acrylic acid (AA), and azobisisobutyro After dissolving 0.1 g of nitrile (AIBN) in 10 g of ethyl acetate (EA) and adding a mixed solution over 2 hours, the temperature was raised to 90°C. Second, 0.2 g of AIBN was dissolved in 20 g of EA and added for 1 hour. After adding the second mixture, polymerization was performed at 90° C. and 100 rpm for 1 hour to prepare an acrylic pressure-sensitive adhesive. The content of each component is shown in Table 1.

In addition, a first adhesive layer was prepared by mixing a crosslinking agent with the acrylic pressure-sensitive adhesive composition, applying the film to a thickness of 19 μm, and drying it by heating at 110° C. for 3 minutes. A second adhesive layer was prepared in the same manner and laminated on both sides of a PET substrate having a thickness of 12 μm to prepare a high heat-resistant tape having a total thickness of 50 μm. The manufactured high heat-resistant tape is composed of a first high heat-resistant acrylic adhesive layer 110 , a base layer 100 , and a second high heat-resistant acrylic adhesive layer 120 as shown in FIG. 1 .

SEBS-g-MA BAM GMA 2-EHAM EAM β-CEA AA AIBN Example 1 80g - 4.2g 35g 20g 4g 4g 0.3g Example 2 70g - 4.2g 40g 22g 4.5g 4.5g 0.3g Example 3 60g - 4.2g 45g 24g 5g 5g 0.3g Example 4 50g - 4.2g 50g 26g 5.5g 5.5g 0.3g Comparative Example 1 80g 4.2g 35g 20g 4g 4g 0.3g Comparative Example 2 30g 4.2g 85g 20g 4g 4g 0.3g

Example 2

In a 4-neck flask, 70 g of SEBS-g-MA having a maleic anhydride content of 2%, 4.2 g of glycidyl methacrylate, and 320 g of toluene were placed, and then heated to 70° C. and stirred for 30 minutes. Next, a solution of 40 g of 2-EHAM and 22 g of EAM, 4.5 g of β-CEA, 4.5 g of AA, and 0.1 g of AIBN dissolved in 10 g of EA was added over 2 hours, and then the temperature was raised to 90°C. Second, 0.2 g of AIBN was dissolved in 20 g of EA and added for 1 hour. After adding the second mixture, polymerization was performed at 90° C. and 100 rpm for 1 hour to prepare an acrylic adhesive, and then a high heat-resistant tape was prepared in the same manner as in Example 1. The content of each component is shown in Table 1.

Example 3

In a 4-neck flask, 60 g of SEBS-g-MA having a maleic anhydride content of 2%, 4.2 g of glycidyl methacrylate, and 320 g of toluene were placed, and then heated to 70° C. and stirred for 30 minutes. Next, a solution of 45 g of 2-EHAM and 24 g of EAM, 5 g of β-CEA, 5 g of AA, and 0.1 g of AIBN dissolved in 10 g of EA was added over 2 hours, and then the temperature was raised to 90°C. Second, 0.2 g of AIBN was dissolved in 20 g of EA and added for 1 hour. After adding the second mixture, polymerization was performed at 90° C. and 100 rpm for 1 hour to prepare an acrylic adhesive, and then a high heat-resistant tape was prepared in the same manner as in Example 1. The content of each component is shown in Table 1.

Example 4

In a 4-neck flask, 50 g of SEBS-g-MA having a maleic anhydride content of 2%, 4.2 g of glycidyl methacrylate, and 320 g of toluene were placed, and then heated to 70° C. and stirred for 30 minutes. Next, a solution of 50 g of 2-EHAM, 26 g of EAM, 5.5 g of β-CEA, 5.5 g of AA, and 0.1 g of AIBN dissolved in 10 g of EA was added over 2 hours, and then the temperature was raised to 90°C. Second, 0.2 g of AIBN was dissolved in 20 g of EA and added for 1 hour. After adding the second mixture, polymerization was performed at 90° C. and 100 rpm for 1 hour to prepare an acrylic adhesive, and then a high heat-resistant tape was prepared in the same manner as in Example 1. The content of each component is shown in Table 1.

Comparative Example 1

After putting 80 g of butyl acrylate monomer (BAM), 4.2 g of methacrylate, and 320 g of toluene in a four-necked flask, it was heated to 70° C. and stirred for 30 minutes. Next, 35 g of 2-ethylhexyl acrylate monomer (2-EHAM), 20 g of ethyl acrylate monomer (EAM), 4 g of beta-carboxylethyl acrylate (β-CEA), 4 g of acrylic acid (AA), and azobisisobutyro After dissolving 0.1 g of nitrile (AIBN) in 10 g of ethyl acetate (EA) and adding a mixed solution over 2 hours, the temperature was raised to 90°C. Second, 0.2 g of AIBN was dissolved in 20 g of EA and added for 1 hour. After adding the second mixture, polymerization was performed at 90° C. and 100 rpm for 1 hour to prepare an acrylic adhesive, and then a high heat-resistant tape was prepared in the same manner as in Example 1. The content of each component is shown in Table 1.

Comparative Example 2

In a 4-neck flask, 30 g of SEBS-g-MA having a maleic anhydride content of 2%, methacrylate 4.2 g, and toluene 320 g were put, and then heated to 70° C. and stirred for 30 minutes. Next, 85 g of 2-ethylhexyl acrylate monomer (2-EHAM), 20 g of ethyl acrylate monomer (EAM), 4 g of beta-carboxylethyl acrylate (β-CEA), 4 g of acrylic acid (AA), and azobisisobutyro After dissolving 0.1 g of nitrile (AIBN) in 10 g of ethyl acetate (EA) and adding a mixed solution over 2 hours, the temperature was raised to 90°C. Second, 0.2 g of AIBN was dissolved in 20 g of EA and added for 1 hour. After adding the second mixture, polymerization was performed at 90° C. and 100 rpm for 1 hour to prepare an acrylic adhesive, and then a high heat-resistant tape was prepared in the same manner as in Example 1. The content of each component is shown in Table 1.

The physical properties of each high heat-resistant tape were measured as follows.

Measurement of initial adhesive force of adhesive

It was measured using a ball tack tester (Gibei E&T, KP-M2300). The angle of the measuring swash plate was set to 30 degrees.

Measurement of change in peel force of adhesive

Cut high heat-resistant adhesive tape to 25mm in width and 300mm in length, use a 2kg roller to reciprocate once at a speed of 300mm/min, press it onto a SUS 304 steel plate, leave it for 30min, and then peel it at a speed of 300mm/min. 180 degree peel force was measured using a strength tester (Gibei E&T, KP-M2T).

Measurement of adhesive holding force

180 ^o Retaining force (85℃) is obtained by attaching high heat-resistant adhesive tape to SUS 304 steel plate at 25 x 25mm and then using a 2kg roller to reciprocate and press twice at a speed of 25mm/sec. Holding power at 85℃ The tester (Gibei E&T, KP-M2606) was left at a load of 1 kg for 24 hours in a chamber to measure the distance pushed or the time it fell.

In addition, 90 ^o holding force (85℃) is after attaching the high heat-resistant adhesive tape to the SUS 304 steel plate at 25 x 100mm, using a 2kg roller to reciprocate twice at a speed of 25mm/sec, and press the holding at 85℃ temperature. In a power tester (Gibai E&T, KP-M2606) chamber, ^{a 100 g load was applied in the 90 o} direction and left for 24 hours to measure the pushed distance or fall time.

Table 2 shows the results of evaluating the physical properties of the high heat-resistant adhesive tape.

item initial adhesion peel force 180 ^o holding force (85℃) 90 ^o holding force (85℃) Example 1 9 1428 gf/inch 1mm 21 mm Example 2 8 1664 gf/inch 2mm 32 mm Example 3 7 1758 gf/inch 3mm 44 mm Example 4 7 1917 gf/inch 5mm 50 mm Comparative Example 1 8 2188 gf/inch 11mm 1hr Drop Comparative Example 2 7 2049 gf/inch 8mm 4hr Drop

Looking at the results in Table 2, it was found that the initial adhesive strength was the best in Example 1. In order for the ball rolling along the ramp to stop, sufficient fluidity and diffusion rate of the polymer chain are required. As the monomer content increases, the polymer supporting the ball on the surface is disturbed, and the chain becomes harder, so the initial adhesive force is It was found to be due to a greater decrease.

On the other hand, Example 4 was the best in the peel force measurement, which is thought to be due to an increase in the content of the monomer imparting tackiness.

In general, the retention force measurement results tend to increase as the cohesive force of the inner polymer chain increases. The holding power at room temperature was the best in Example 4 containing a lot of acrylic functional groups. Under the high temperature condition of 90℃, the structure collapses due to the unreacted monomer and the remaining solvent inside the adhesive material, and it can be seen that the holding power is reduced.

In addition, in Comparative Example 1, in which BAM, a monomer that imparts tackiness to a general acrylic pressure-sensitive adhesive, was added in the same amount instead of SEBS-g-MA, it was confirmed that the peel force measurement result was the best, but the heat resistance was greatly reduced.

As described above, it can be seen that the acrylic adhesive manufactured by applying the manufacturing method of the present invention exhibits excellent physical properties when applied to a high heat-resistant adhesive tape due to improved heat resistance while having an adhesive strength equivalent to that of a conventional acrylic adhesive.

Although the present invention has been described with reference to the preferred embodiment as described above, it is not limited to the above embodiment, and various modifications and changes made by those skilled in the art to which the present invention pertains within the scope of the present invention are not departed from. change is possible Such modifications and variations are intended to fall within the scope of the present invention and the appended claims.

100: base layer
110: first high heat-resistant acrylic adhesive layer
120: second high heat-resistant acrylic adhesive layer

Claims (5)

Acrylic with improved heat resistance, characterized in that it comprises the step of grafting the adhesive monomer to the SEBS polymer by mixing a sticky monomer and a radical initiator with a styrene-ethylene-butylene-styrene (SEBS) polymer grafted with maleic anhydride A method for manufacturing an adhesive.
The method according to claim 1,
The adhesive monomer is glycidyl methacrylate, 2-ethylhexyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate (methyl) methacrylate), beta-carboxyl ethyl acrylate (β-carboxyl ethyl acrylate), acrylic acid (acrylic acid), characterized in that any one or more selected from a method for producing an acrylic pressure-sensitive adhesive with improved heat resistance.
The method according to claim 1,
The radical initiator is azobisisobutyronitrile, di- (2,4-dichlorobenzoyl) peroxide (di- (2,4-dichlorobenzoyl)-peroxide), dibenzoyl peroxide (dibenzoyl peroxide), di -t-butyl peroxybenzoate (di(t-butyl peroxybenzoate)), dicumyl peroxide (dicumyl peroxide), di-t-butylperoxide (di-t-butylperoxide), 1,1-di- (t- Butylperoxy)-3,3,5-trimethylcyclohexane (1,1-di-(t-butylperoxy)-3,3,5-trimethylcyclohexane), di-(t-butylperoxyisopropyl)benzene (di -(t-butylperoxyisopropyl)benzene, PK-14), t-butylcumylperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexane (2,5- A method for producing an acrylic pressure-sensitive adhesive with improved heat resistance, characterized in that one or more selected from dimethyl-2,5di(t-butylperoxy)-hexane).
The method according to claim 1,
The method for producing an acrylic adhesive with improved heat resistance, characterized in that the SEBS polymer grafted with maleic anhydride is included in an amount of 25 to 60 parts by weight based on 100 parts by weight of the acrylic adhesive.
The method according to claim 1,
The method for producing an acrylic pressure-sensitive adhesive having improved heat resistance, characterized in that the radical initiator is included in an amount of 0.2 parts by weight based on 100 parts by weight of the acrylic pressure-sensitive adhesive.

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