KR100930808B1 - Epoxy acrylic pressure-sensitive adhesive manufacturing method comprising a rosin ester-based built-in tackifier resin and epoxy acrylic pressure-sensitive adhesive thereby - Google Patents

Abstract

The present invention relates to a method for producing an epoxy acrylic pressure-sensitive adhesive containing a rosin ester-based built-in pressure-sensitive adhesive resin and an epoxy acrylic pressure-sensitive adhesive by this, so-called anchoring (anchoring) through the step in which rosin is selected and included as an adhesive resin in the epoxy acrylic pressure-sensitive adhesive The present invention relates to an epoxy acrylic pressure-sensitive adhesive manufacturing method and an epoxy acrylic pressure-sensitive adhesive according to which the initial adhesive force, the adhesive force as well as the cohesive force is significantly improved.

Description

Epoxy acrylic pressure-sensitive adhesive manufacturing method comprising a rosin ester-based internal pressure-sensitive adhesive resin, and epoxy acrylic pressure-sensitive adhesive by the same {Method for manufacturing epoxy functionalized acrylic pressure-sensitive adhesives containing pendent rosin ester tackifier}

The present invention relates to a method for producing an epoxy acrylic pressure-sensitive adhesive containing a rosin ester-based built-in pressure-sensitive adhesive resin and an epoxy acrylic pressure-sensitive adhesive by this, and in more detail through the step in which rosin is selected and included as an adhesive resin in the epoxy acrylic pressure-sensitive adhesive, The present invention relates to an epoxy acrylic pressure-sensitive adhesive manufacturing method and an epoxy acrylic pressure-sensitive adhesive according to which the initial adhesive force, the adhesive force as well as the cohesive force is significantly improved by the so-called anchoring effect.

The pressure-sensitive adhesive is a material that is sufficiently adhered to the adherend only by the pressure applied, and exhibits a low cohesive force, fast stress relaxation, and viscoelastic behavior in which deformation easily occurs with respect to external force.

The raw materials used in the pressure-sensitive adhesive is a thermoplastic resin such as natural rubber, synthetic rubber, acrylic, silicone, etc., and most of them have elastic properties. Thus, low-molecular-weight substances are mixed and used to give viscoelastic properties.

Among the raw materials of the pressure-sensitive adhesives, acrylic pressure-sensitive adhesives are rapidly increasing in use in place of rubber pressure-sensitive adhesives, and can be used in a wide range of forms such as solvent type, aqueous emulsion type, hot melt type, and 100% solid reactive pressure sensitive adhesives. It is excellent in weather resistance, heat resistance, cold resistance, oil resistance, etc. compared to rubber-based adhesives and can be made relatively easily according to various purposes and uses. Therefore, it can be said that the adhesive product can be used for a variety of uses as is the current origin of the acrylic adhesive. When the acrylic adhesive contains an epoxy group, it exhibits heat resistance, weather resistance and excellent adhesive properties due to the inherent properties of epoxy.

However, adhesives containing epoxy functional groups are generally crosslinked by adding a crosslinking agent. This method is a two-component method in which a crosslinking agent should be added separately. There are many difficulties in maintaining uniformity.

In general, the adhesive properties can be evaluated by the adhesive strength (tack), adhesion (adhesion) and shear strength (shear strength). The initial adhesive force is related to the glass transition temperature (Tg) of the polymer constituting the adhesive, and the adhesive force is related to the glass ion temperature and cohesive force of the polymer. The cohesive force is a force that appears between the molecules of the adhesive when the adhesive is applied to the adherend. If the cohesion between molecules is high, the interface breakdown of the adhesive occurs. It is ideal to design the adhesive so that breakage occurs.

In general, a tackifier resin, which is a low molecular weight material, is added to impart viscous properties to the pressure-sensitive adhesive to improve adhesion performance. When the adhesive resin is added, the initial adhesive force (tack) and the adhesion force (adhesion) increase, but there is a problem in that the cohesion force is reduced by reducing the attraction force by widening the interval between the polymer chains.

 The present inventors have developed an epoxy acrylic pressure-sensitive adhesive including a rosin ester-based built-in pressure-sensitive adhesive in order to solve the above problems caused by the addition of the pressure-sensitive adhesive resin used in the conventional pressure-sensitive adhesive.

Accordingly, one object of the present invention is to propose a method for producing an epoxy acrylic pressure-sensitive adhesive containing a rosin ester-based tackifying resin.

Another object of the present invention is to increase the initial tack and adhesion, and not to deteriorate the shear strength, but rather to improve the epoxy acrylic-based resin comprising a rosin ester-based embedded tackifier. It is to provide an adhesive.

The adhesive according to the present invention does not deteriorate the shear strength while increasing the initial tack and adhesion, which are the roles of the conventional tackifying resin, by the anchoring effect, which is a physical crosslinking phenomenon caused by the embedded tackifying resin. In addition, there are characteristics that can be improved.

In order to achieve the above object, the epoxy acrylic pressure-sensitive adhesive manufacturing method comprising a rosin ester-based built-in tackifying resin according to the present invention,

Acrylate polymer synthesis step comprising epoxy functional group;

Blending the polymer with the rosin ester-based tackifying resin; And

And a post heat treatment step of the blending mixture.

The present invention is not limited, but in the step of synthesizing the acrylate polymer including the epoxy functional group, it may proceed by solution polymerization, and 2-ethylhexyl acrylate, butyl acrylate, and glycidyl methacrylate are dissolved in a solvent. Characterized in that the polymerization is initiated. At this time, preferably 2,2'-azobisisobutylonitrile may be used as the thermal initiator. The polymerization step may proceed with the reaction for 1 hour at 65 ℃. In addition, the rosin in the blending step is toluene It may be diluted and the blending mixture may be dried at 50 ° C. for 10 minutes. On the other hand, the post-heat treatment step, preferably, it may be a post-heat treatment for 30 minutes at 50 ° C to 170 ° C each for 20 minutes intervals.

Example (Epoxy acrylic pressure-sensitive adhesive manufacturing step comprising a rosin ester-based internal pressure-sensitive adhesive resin)

First step : acrylate polymer synthesis step including epoxy functional group

The acrylate polymer containing an epoxy functional group was synthesize | combined using the solution polymerization method. The polymerization was carried out in a 500-ml four-necked flask equipped with a stirrer, a thermometer and a condenser. 75.0 wt.% 2-EHA (2-ethylhexyl acrylate, formula 1, purity 99.0%, Junsei Chemicals, Japan), 15.0 wt.% BA (butyl acrylate, formula 2, purity 99.0%, Junsei Chemicals, Inc. , Japan) and 10.0 wt.% GMA (glycidylmethacrylate, Formula 3, purity 98.0%, Junsei Chemicals, Japan) mixture after addition of 0.2 wt. A% AIBN (2,2'-azobisisobutylonitrile, formula 4) thermal initiator was added. The mixture was reacted at 65 ° C. at 400 rpm for 1 hour, and further 0.4 wt.% AIBN was dissolved in 140 ml of ethyl acetate solvent and added three more times for 7 hours to participate in the polymerization of unreacted monomers.

Second step : rosin ester-based embedded tackifying resin blending step

Toluene to the acrylate polymer containing the epoxy functional group, synthesized in the first step Rosin (DX-100, Lactone Korea, see Formula 5) containing 50 wt.% Of diluted carboxylic acid functionalities was blended by varying from 0 wt.% (R0) to 30 wt.% (R30) relative to the polymer. . The mixed solution was coated on a corona treated polyethylene terephthalate (Polyester film, SKC Co. Ltd., S. Korea) having a thickness of 20 μm using a bar coater (No. 26) and dried in a 50 ° C. oven for 10 minutes. . Rosin is obtained by a solvent extraction method, and a plurality of resin acids described in the formula (5) such as neobiate, repopimaric acid, hydroavietic acid, pimaric acid and dextonic acid are mainly composed of abiate acid ( It contains, and a mixture thereof is defined as rosin in the present invention.

Third step : post heat treatment step

In order to form a covalent bond between the rosin and the polymer chain, each heat treatment was performed for 30 minutes at 50 ° C. to 170 ° C. at 20 ° C. intervals for 30 minutes, thereby preparing an epoxy acrylic pressure-sensitive adhesive including a rosin ester-based embedded tackifying resin according to the present invention.

Experimental Example 1 (Identification of the formation mechanism of the built-in tackifying resin)

The formation mechanism of the built-in tackifying resin of the post-heat-treated adhesive using FTIR (JASCO FTIR-6300) was investigated. Conversion rate of the epoxy group is an epoxy ring vibration absorption peak of the 842cm ^-1 waveband, a conversion rate of the acid was determined by the absorption peak of 1695 cm ^-1 wavelength. -OH generated by the chemical bonding of the carboxylic acid and epoxy rosin ester -CO-O- in an absorption wavelength range 1339 cm ^-1 is examined in an absorption wavelength band 1245cm ^-1. 1717 cm ⁻¹ , a stretching vibration wavelength band of C═O, was taken as an internal reference (see FIG. 1). The conversion rate was calculated using the following formula.

here,

: 후 열처리한 점착제의 에폭시 혹은 카르복실산의 흡수피크 면적

: Absorption peak area of epoxy or carboxylic acid of adhesive after heat treatment

: 후 열처리한 점착제의 C=O 흡수피크 면적

: C = O absorption peak area of adhesive after heat treatment

: 후 열처리하기 전 점착제의 에폭시 혹은 카르복실산의 흡수피크 면적

: Absorption peak area of epoxy or carboxylic acid of adhesive before heat treatment

: 후 열처리하기 전 점착제의 C=O 흡수피크 면적.

: C = O absorption peak area of pressure-sensitive adhesive before post-heat treatment.

Through the FTIR, the conversion of epoxy (842cm _-1 ) and carboxyl group (1695cm ^-1 ) with the post-heat treatment temperature was examined. Epoxy showed 58% conversion and carboxyl group showed 83% conversion at 170 ° C. after the maximum heat treatment (see FIG. 2). It can be seen that the carboxylic acid of the rosin and the epoxy of the polymer main chain form a covalent bond by thermal reaction. As the post-heat treatment temperature increases, the absorption peak of ester (-CO-O-) produced by the coupling reaction between carboxylic acid and epoxy is continuously increased (Fig. 3). It can be seen that the absorption ratio decreases (FIG. 4). From this, it can be seen that hydroxy generated by the coupling reaction between carboxylic acid and epoxy causes esterification reaction with carboxylic acid of rosin. That is, it means that two rosin ester-based tackifying resin is formed in one epoxy group (Fig. 5). This corresponds to the experimental value of about 25% higher carboxyl group conversion than epoxy conversion.

Experimental Example 2 (Identification of Glass Transition Temperature)

Each pressure-sensitive adhesive samples prepared in Examples according to the present invention were heated at a heating rate of 10 ° C./min in the range of −80 to + 250 ° C. using DSC (TA, Q-1000) to obtain a glass transition temperature (Tg). . Tg was determined as the midpoint of the DSC curve.

In Figure 6, when rosin 30wt.% Blended to the epoxy acrylate polymer (R30) it can be seen that the glass transition temperature (Tg) drops from -33.9 ℃ to -45.7 ℃. This is because rosin, a low molecular weight resin, enters the polymer chain and increases the spacing between the chains, thereby reducing the attraction between them. However, when the heat treatment is carried out at 170 ° C. (R30_170), the hard rosin is attached to the polymer main chain, and thus the glass transition temperature (Tg) is increased again due to the polymer movement.

Experimental Example 3 (Single Lap Shear Experiment)

Using a universal strength tester (UTM, Zwick Co.) was tested at a crosshead speed of 60mm / min at 20 ± 2 ℃ room temperature. The adhesive was laminated | stacked on the PE film of 80 micrometers thickness by 10 mm x 10 mm x 20 micrometers. Single lap shear adhesive strength was calculated as the average value of five samples by dividing the maximum load value by the lamination area.

It can be seen that the single lap shear strength increases as the post-heat treatment temperature is increased in sample R30 (FIG. 7). This is because the rosin tackifier resin penetrated between the polymer chains during the blending process undergoes a coupling reaction by a heat source and is converted into a tackifier resin, so that the polymer chain is anchored by the anchoring effect, which is a physical crosslinking phenomenon between the hard tackifier resins. This is because hepatic cohesion is increased (FIG. 8).

 In addition, in FIG. 9, all of the R30 series having different post-heating temperatures compared to the R0 pressure-sensitive adhesive made of pure acrylate polymer showed high adhesive energy overall.

Experimental Example 4 (Probe Tag Experiment)

The tack of the adhesive was measured by a probe tack method using a texture analyzer. The maximum strength required when the stainless steel probe having a diameter of 5 mm was brought into contact with the adhesive tape surface with a force of 100 g for 1 second and then peeled from the surface in the vertical direction was set as the initial adhesive force (F _max ). Peeling rate was 60mm / min, was tested at 25 ℃, relative humidity 50% constant temperature and humidity conditions.

As described above, when the tackifier resin is added, adhesive strength increases but cohesiveness decreases, and when chemical crosslinking is performed to improve cohesion, adhesive strength decreases and shrinkage occurs. However, the epoxy acrylic pressure-sensitive adhesive containing the rosin ester-based built-in tackifier according to the present invention solves all the problems of the conventional tackifier resin and chemical crosslinking to realize the ideal adhesive performance to improve the adhesion and cohesion simultaneously. Can be.

1, FTIR peak characteristics of the epoxy acrylic pressure-sensitive adhesive containing a rosin ester-based tackifying resin according to the present invention: ketone (1717 cm ^-1 ), carboxylic acid (1695 cm ^-1 ), hydroxy (1339 cm ^-1 ) , ester (1245cm ^-1 ) and epoxy (842 cm ^-1 )

2 is a measurement diagram showing the epoxy conversion of the R0 and R30 adhesive tape and the carboxylic acid conversion of the R30 adhesive tape according to the post-heat treatment temperature change,

Figure 3 is a measurement showing the ester (1245cm ^-1 ) formation process according to the post-heat treatment temperature change of the R30 adhesive tape confirmed through FTIR,

4 is a measurement diagram showing the absorption ratio of hydroxy (1339cm ^-1 ) to ketone (1717 cm ^-1 ) according to the change in heat treatment temperature after confirming through FTIR,

Figure 5 is a schematic diagram of the formation mechanism of the rosin ester-based tackifier resin in the epoxy acrylic pressure-sensitive adhesive,

6 is a glass transition temperature measurement diagram of R0, R30 and R30_170 confirmed by DSC,

7 is a single lap shear strength measurement of R0 and R30 according to the post-heat treatment temperature change,

8 is a schematic view of the anchoring effect by the rosin ester-based tackifying resin,

9 is a graph illustrating adhesion energy (G _tack ) of R 0 and R 30 according to post-heat treatment temperature changes.

Claims (5)

Acrylate polymer synthesis step comprising epoxy functional group; Blending a rosin-based tackifying resin including a carboxyl functional group with the polymer; And It comprises a post-heat treatment step of the blending mixture to form a covalent bond with the epoxy group and the carboxyl group, wherein the post-heat treatment step is a heat treatment for 30 minutes each at 20 ℃ interval from 50 ℃ to 170 ℃, rosin ester Epoxy acrylic pressure-sensitive adhesive manufacturing method comprising a built-in tackifier resin. The method of claim 1, wherein the step of synthesizing the acrylate polymer comprising an epoxy functional group, rosin ester system, characterized in that the solution polymerization of 2-ethylhexyl acrylate, butyl acrylate, and glycidyl methacrylate Epoxy acrylic pressure-sensitive adhesive manufacturing method comprising a built-in tackifier resin. The method of claim 2, wherein the solution polymerization is 2,2'- azobisisobutylonitrile, characterized in that used as a thermal initiator, rosin ester-based adhesive acrylic resin manufacturing method comprising a rosin-based tackifier resin. delete An epoxy acrylic pressure-sensitive adhesive prepared according to claim 1, comprising a rosin ester-based built-in pressure-sensitive adhesive resin by covalent bonding of a carboxyl group of a rosin-based tackifier resin and an acrylic epoxy.

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