KR102500333B1 - Adhesive compostion having improved pigment dispersion and adhesive sheet using the same - Google Patents

Abstract

The present invention relates to a pressure-sensitive adhesive composition having excellent pigment dispersibility and a pressure-sensitive adhesive sheet using the pressure-sensitive adhesive composition, wherein the pressure-sensitive adhesive composition is composed of acrylic syrup, a colorant, a photopolymerization initiator, and a crosslinking agent and does not contain a solvent, Acrylic syrup contains a monomer selected from monofunctional carboxylic acid esters and unsaturated dicarboxylic acid diesters, and is prepared through mass polymerization using a thermal initiator. The pressure-sensitive adhesive sheet prepared using the pressure-sensitive adhesive composition is It has high pigment dispersibility, excellent visibility, and excellent adhesion, so it shows excellent effects in the attachment of POLED for automobiles.

Description

Pressure-sensitive adhesive composition having excellent pigment dispersibility and pressure-sensitive adhesive sheet using the same

The present invention relates to a pressure-sensitive adhesive composition having excellent pigment dispersibility and a pressure-sensitive adhesive sheet using the same, and more particularly, to a pressure-sensitive adhesive composition capable of improving the dispersibility of pigment particles by adding an ester bond to an acrylic resin for pressure-sensitive adhesive, and the pressure-sensitive adhesive It relates to an adhesive sheet using the composition.

Recently, a flexible display, POLED (Plastic Organic Light Emitting Diode) panel is applied instead of LCD to maximize the curved shape and internal area of the dashboard or front glass inside the car, and some high-end vehicles has already been applied in some cases.

When attaching automotive POLEDs to dashboards or windshields, since POLEDs have the form of thin panels, mechanical attachments such as bolts are impossible and pressure sensitive adhesives (PSAs) must be used to attach them. One thing to consider in the application of POLED is that it must have durability even in extreme environmental changes to which automobiles are exposed. Not only the reliability of the POELD panel itself, but also the adhesive tape for panel attachment must have strong durability reliability in extreme environments, from a minimum temperature of minus 30℃ during a cold wave in winter and a maximum temperature of 80℃ during a heat wave in summer.

In order to apply it to a display for a CID (Center Information Display) of an automobile, an adhesive material capable of satisfying characteristics such as cold resistance, heat resistance, and high reliability must be developed. In addition, it is necessary to exhibit light blocking properties capable of securing high visibility of the POLED while maintaining stable adhesive properties according to the substrate. In order to secure such high visibility, it is necessary to manufacture a pressure-sensitive adhesive sheet using a pressure-sensitive adhesive composition having high pigment dispersibility.

For example, Korean Patent Registration No. 10-1979686 discloses a pressure-sensitive adhesive composition comprising an adhesive resin having a weight average molecular weight of 200,000 to 2 million and a resin dispersant having a weight average molecular weight of 1,000 to 100,000 while maintaining the dispersibility of the pigment. An optical pressure-sensitive adhesive capable of exhibiting adhesive strength is disclosed. Although the prior art pressure-sensitive adhesive composition has added a dispersant to improve pigment dispersibility, it can be seen as a result suggesting that the pigment dispersibility can be controlled by the type of resin or resin dispersant constituting the pressure-sensitive adhesive composition.

Republic of Korea Patent Registration No. 10-1979686

The present invention has been made in view of the prior art as described above, and an object of the present invention is to provide a solvent-free pressure-sensitive adhesive composition capable of exhibiting excellent adhesive strength in a wide temperature range while improving pigment dispersibility.

In addition, it is an object of the present invention to provide a pressure-sensitive adhesive sheet that is easy to attach a POLED by using the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition of the present invention for solving the above problems is composed of an acrylic syrup, a colorant, a photopolymerization initiator, and a crosslinking agent, and does not contain a solvent, and the acrylic syrup contains a monofunctional carboxylic acid ester and an unsaturated It includes a monomer selected from dicarboxylic acid diesters, and is characterized in that it is prepared through bulk polymerization using a thermal initiator.

At this time, the monofunctional carboxylic acid ester is 2-(meth)acryloyloxy ethyl succinate, 2-(meth)acryloyloxy propyl succinate, 4-methacryloyloxy ethyl succinate, 4-(meth)acryloyloxy butyl succinate, 2-(meth)acryloyloxy ethyl phthalate, 2-(meth)acryloyloxy propyl phthalate , 4-(meth)acryloyloxy butyl phthalate, 2-(meth)acryloyloxy ethyl terephthalate, 4-methacryloyloxy butyl terephthalate (4-(meth) acryloyloxy butyl terephthalate), 2-(meth)acryloyloxy ethyl terephthalate, 2-(meth)acryloyloxy ethyl hexahydro phthalate, 2-methacryloxy propyl Hexahydrophthalic acid (2-(meth)acryloyloxy propyl hexahydro phthalate), 4-methacryloyloxy butyl hexahydrophthalate (4-(meth)acryloyloxy butyl hexahydro phthalate), 2-acryloxyethyl-2-hydroethyl phthalate (2 -acryloyloxyethyl-2-hydroxyethyl phthalate).

In addition, the unsaturated dicarboxylic acid diester is dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, diethyl fumarate ), dibutyl fumarate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, methyl ethyl fumarate, methyl butyl fumarate butyl fumarate) and methyl ethyl itaconate.

In addition, the monomer is contained in the range of 2 to 30% by weight based on the total weight of the acrylic syrup, and the colorant is contained in the range of 4 to 10% by weight based on the total weight of the acrylic syrup, thereby achieving high pigment dispersibility. will do

The pressure-sensitive adhesive sheet of the present invention is characterized by comprising the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition according to the present invention exhibits excellent adhesive strength in a wide temperature range while improving pigment dispersibility.

In addition, the pressure-sensitive adhesive sheet prepared using the pressure-sensitive adhesive composition has high visibility and excellent adhesive strength, so it is effective for attaching POLEDs.

Figure 1 is a result of measuring the pigment dispersibility of the pressure-sensitive adhesive composition according to Examples and Comparative Examples with an optical microscope at 200 magnification, Example 1 (a), Example 2 (b), Example 3 (c), Comparative Example This is the measurement result of Example 1 (d).

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

The pressure-sensitive adhesive composition of the present invention is a solvent-free pressure-sensitive adhesive composition that does not contain a solvent, and is characterized in that it consists of acrylic syrup, a colorant, a photopolymerization initiator, and a crosslinking agent. The pressure-sensitive adhesive composition contains pigment particles as a colorant. In order to improve the dispersibility of the pigment particles, an acrylic syrup containing a monomer selected from monofunctional carboxylic acid esters and unsaturated dicarboxylic acid diesters is used. Through this, high pigment dispersibility can be obtained.

In particular, the acrylic syrup is prepared through bulk polymerization using a thermal initiator, and through this, it is possible to prepare a solvent-free adhesive composition without using a solvent. The bulk polymerization is a method of polymerization using only monomers without using a solvent, and is a manufacturing method in which the apparatus is simple and the reaction is fast, a high yield and high purity polymer can be obtained, and the polymer can be handled as it is. However, due to the exothermic reaction of the polymer, there are problems such as difficult temperature control and wide molecular weight distribution. In the present invention, an optimized combination of types and contents of monomers is applied so that acrylic syrup can be prepared through bulk polymerization.

In addition, carbon black may be used as the colorant. As a monomer for increasing the dispersibility of the carbon black, one or more monomers selected from the monofunctional carboxylic acid esters and unsaturated dicarboxylic acid diesters may be used. It can be used to prepare a solvent-free pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition is effective in dispersing carbon black and exhibits excellent pigment dispersibility. This is to show the effect of improving the light-shielding performance when the adhesive sheet is manufactured.

The monofunctional carboxylic acid ester may be obtained through a half-ester reaction between a hydroxyalkyl methacrylate and a carboxylic acid anhydride. Examples of the hydroxyalkyl methacrylate include 2-hydroxy ethyl methacrylate, 2-hydroxy propyl methacrylate, and 4-hydroxy butyl methacrylate ( 4-hydroxy butyl methacrylate). Further, examples of the carboxylic acid anhydride include succinic anhydride, phthalic anhydride, terephthalic anhydride, hexahydrophthalic anhydride, and trimellitic anhydride. there is.

Monofunctional carboxylic acid esters obtained through the half-ester reaction include 2-(meth)acryloyloxy ethyl succinate, 2-methacryloyloxy propyl succinate (2-(meth)acryloyloxy propyl succinate), 4-(meth)acryloyloxy butyl succinate, 2-(meth)acryloyloxy ethyl phthalate, 2-methacryloyloxy propyl phthalate (2-( meth)acryloyloxy propyl phthalate), 4-(meth)acryloyloxy butyl phthalate, 2-methacryloyloxy ethyl terephthalate, 4-methacryloyloxy butyl terephthalate (4-(meth)acryloyloxy butyl terephthalate), 2-(meth)acryloyloxy ethyl terephthalate, 2-(meth)acryloyloxy ethyl hexahydrophthalate, 2-(meth)acryloyloxy propyl hexahydro phthalate, 4-(meth)acryloyloxy butyl hexahydro phthalate, 2-acryloxyethyl-2 -Any one of hydroethyl phthalic acid (2-acryloyloxyethyl-2-hydroxyethyl phthalate) may be mentioned.

In addition, the unsaturated dicarboxylic acid diesters include dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, and diethyl fumarate. fumarate), dibutyl fumarate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, methyl ethyl fumarate, methyl butyl fumarate ( methyl butyl fumarate) and methyl ethyl itaconate may be used.

The solvent-free pressure-sensitive adhesive composition according to the present invention may be prepared by forming an acrylic syrup containing the monomers, mixing carbon black thereto to prepare a colorant, and mixing the colorant with a crosslinking agent and a photoinitiator.

The acrylic syrup includes one or more of the above monomers, and the monomers are preferably included in the range of 2 to 30% by weight based on the total amount of the acrylic syrup. If it is out of the above range, it is not possible to sufficiently secure the pigment dispersibility, and only the pigment dispersibility to the extent obtained in ordinary pressure-sensitive adhesive compositions can be obtained. Therefore, it is preferable to use it within the above range.

In addition, the acrylic syrup is formed by mixing commonly used acrylic monomers in addition to the above monomers. Examples of the acrylic monomer include acrylic acid, ethyl acetate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexyl methacrylate, n-octyl acrylate, octyl methacrylate, isooctyl acrylate, isooctyl methacrylate, Acrylic monomers constituting ordinary pressure-sensitive adhesive resins such as 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isobornyl acrylate, and isobornyl methacrylate can be used. In addition, the content of the acrylic monomer may be appropriately selected according to the molecular weight and viscosity of the desired acrylic syrup.

Bulk polymerization is performed using a thermal initiator to prepare the acrylic syrup. The thermal initiator may include, but is not limited to, any one or more of a peroxide or an azo-based compound.

In addition, a chain transfer agent may be included to control the molecular weight in order to carry out bulk polymerization. As the chain transfer agent, a compound containing a mercaptan group or a thioglycerol group may be used. Specifically, octylmercaptan, laurylmercaptan, t-nonyl mercaptan, t-dodecyl mercaptan, mercaptoethanol, alpha -Alpha-thioglycerol, thioglycolic acid, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl and decyl thioglycolate, dodecyl thioglycolate, and alpha-methylstyrene dimer. In addition, the chain transfer agent may be used in the range of 0 to 100 parts by weight based on 100 parts by weight of the monomers.

In the bulk polymerization, the reaction is performed until the non-volatile content of the polymer is 30% or more, and the monomer composition is diluted so that the non-volatile content is 30%, so that the viscosity for coating can be easily controlled.

In addition, when performing the bulk polymerization, nitrogen is supplied into the reactor in order to smoothly proceed with the radical polymerization, and when the polymerization proceeds to a certain extent, the ultraviolet irradiation is stopped and nitrogen supply is stopped to control heat generation and radical reaction, , it becomes possible to react so that the non-volatile content is 30% or more.

Specifically, when the bulk polymerization is performed, in order to control the exotherm and polymerization of radical polymerization, nitrogen is supplied into the reactor until the initial polymerization starts, and when the exothermic reaction occurs, air and nitrogen are mixed and injected at a volume ratio of 2:1. It is possible to react up to 30% or more of non-volatile content by controlling heat generation and radical reaction with cooling water while doing so.

A colorant can be prepared by mixing carbon black with the acrylic syrup. To this end, the colorant can be prepared by dispersing the carbon black by adding 4 to 10% by weight of carbon black with respect to the total amount of the prepared acrylic syrup. In addition, a dispersant may be added to facilitate dispersion in the process of preparing the colorant, and the amount of the dispersant may be in the range of 0.1 to 2% by weight based on the total amount of the acrylic syrup.

After preparing the colorant in this way, a non-solvent pressure-sensitive adhesive composition capable of photocuring is obtained by mixing an acrylic crosslinking agent composed of a bifunctional or higher-functional acrylic monomer and a photopolymerization initiator.

Examples of the acrylic crosslinking agent include triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, and dipropylene glycol diacrylate. ), tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate Acrylate (1,6-hexanediol diacrylate), 1,9-nonanediol diacrylate (1,9-nonanediol diacrylate), neopentyl glycol diacrylate (neopentyl glycol diacrylate), dimethylol tricyclodecane diacrylate ( dimethylol-tricyclodecane diacrylate), bisphenol A ethylene oxide adduct diacrylate, bisphenol A propylene oxide adduct diacrylate, hydroxypivalate neopentylglycol diacrylate hydroxypivalate neopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, alkoxylated dimethyloltricyclodecane diacrylate, polytetramethylene glycol diacrylate), trimethylolpropane triac Trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, tri(propylene glycol) triacrylate, caprolactone modified trimethylolpropane triacrylate trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritolethoxy tetraacrylate, dipentaerythritol hexaacrylate, di-trimethyl Ditrimethylolpropane tetraacrylate, glyceryl propoxy triacrylate, caprolactam modified dipentaerythritol hexaacrylate, alkoxylated cyclohexanone dimethanol diacrylate ( alkoxylated cyclohexanone dimethanol diacrylate, alkoxylated hexanediol diacrylate, dioxane glycol diacrylate, dioxane glycol diacrylate, cyclohexanone dimethanol diacrylate cyclohexanone dimethanol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate acrylate), propoxylated glycerine triacrylate, propoxylated trimethylolpropane triacrylate, di-trimethylolpropane tetraacrylate, dipentaeth dipentaerythritol pentaacrylate and ethoxylated pentaerythritol tetraacrylate. The acrylic crosslinking agent may be used in the range of 0.01 to 10% by weight with respect to the entire pressure-sensitive adhesive composition, through which residue prevention and adhesive strength can be adjusted.

When manufacturing a pressure-sensitive adhesive sheet using the pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition is applied to the surface of the lower release film, cured by UV irradiation to form a pressure-sensitive adhesive layer, and then the upper release film is laminated to the pressure-sensitive adhesive layer to prepare the pressure-sensitive adhesive sheet. can

The release film includes polyethylene terephthalate, polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, vinyl chloride copolymer, polyurethane, polystyrene, polycarbonate, and fluorine that can be used for optical purposes. Films such as resin, low density polyethylene and triacetylcellulose can be used.

In addition, when the pressure-sensitive adhesive composition is applied to the surface of the release film, methods such as a bar coating method, a reverse roll coating method, a knife coating method, a roll knife coating method, a gravure coating method, a doctor blade coating method, and a slot die coating method may be used. can In addition, the adhesive layer is preferably applied such that the thickness after drying and curing is 30 to 80 μm.

The effects of the pressure-sensitive adhesive composition of the present invention will be described through the following examples.

<Preparation of monomer>

As a monofunctional carboxylic acid ester, 1 mole of phthalic anhydride and 1 mole of 2-hydroxyethyl acrylate were put in a reactor and reacted at 100°C for 4 hours under a nitrogen atmosphere to obtain 2-acryloxyethyl-2-hydroethyl phthalic acid. It was prepared and used, and dibutyl fumaric acid was used as an unsaturated dicarboxylic acid diester.

<Manufacture of acrylic syrup>

[Production Example 1]

After adding 81 g of 2-ethyl hexyl acrylate (2-EHA), 10 g of dibutyl fumaric acid (DBF), 4 g of acrylic acid (AA), and 5 g of 2-hydroxypropyl acrylate (2-HPA) as acrylic compounds, heat under a nitrogen atmosphere. 0.1 g of 2-2-azobis(4-methoxy-2,4-dimethylvaleronitrile) (Wako V-70) as an initiator and 0.05 g of lauryl mercaptan (L-SH) as a chain transfer agent were added and 60 The temperature was raised to °C. Only nitrogen gas was injected until the start of exotherm, and when the start of exotherm, nitrogen and air were injected in a volume ratio of 1:2. After the temperature rose to 117 ° C due to the heat of reaction of the monomers, it was confirmed that the temperature gradually decreased, and the resin obtained by reacting for 4 hours was diluted in the ratio of the acrylic mixture to prepare an acrylic syrup of 30% non-volatile content.

[Production Examples 2-3]

Polymer syrup was prepared in the same manner as in Preparation Example 1, with each composition and content as the composition shown in Table 1 below. In Table 1, AEP is 2-acryloxyethyl-2-hydroethyl phthalic acid, and BAM is n-butyl acrylate.

Preparation Example 1 Preparation Example 2 Preparation Example 3 DBP 10 8 - AEP - 4 - BAM - - 10 2-EHA 81 80 81 AA 4 3 4 L-SH 0.05 0.05 0.05 V-70 0.1 0.1 0.1 Non-volatile content (%) 30 30 30

<Manufacture of colorants>

[Conditioning agent 1]

5% of carbon black was added to the syrup synthesized in Preparation Example 1 and dispersed for 30 minutes using a bead mill to obtain a color conditioner 1.

[Conditioning agent 2]

Color conditioner 2 was obtained by dispersing in the syrup of Preparation Example 2 in the same manner as color conditioner 1.

[Conditioning agent 3]

Color conditioner 3 was obtained by dispersing in the syrup of Preparation Example 3 in the same manner as color conditioner 1.

<Preparation of pressure-sensitive adhesive composition>

A light-curable pressure-sensitive adhesive composition was prepared by mixing the acrylic syrup of Preparation Example of Table 1, the colorant, photopolymerization initiator, and bifunctional acrylate crosslinking agent according to the configuration and composition according to Table 2 below.

Example 1 Example 2 Example 3 Comparative Example 1 acrylic syrup Preparation Example 1 70 70 Preparation Example 2 70 Preparation Example 3 70 colorant Toning agent 1 30 Toner 2 30 30 Toning agent 3 30 cross-linking agent HDDA 0.15 0.15 0.15 0.15 photoinitiator TPO 0.5 0.5 0.5 0.5 Curing conditions Light amount (mJ) 600 600 600 600

A pressure-sensitive adhesive sheet was prepared using the pressure-sensitive adhesive composition as follows.

A 100 μm thick PET film was used as the lower release film, an adhesive layer was formed on the lower release film to have a thickness of 50 μm after curing, and a 75 μm thick PET film was laminated on the adhesive layer as the upper release film. Thus, an adhesive sheet was prepared. When forming the pressure-sensitive adhesive layer, an ultraviolet curing process was performed by irradiating ultraviolet rays with a light amount of 600 mJ.

The adhesive force and dispersibility of the prepared adhesive sheet were measured.

Adhesion was measured using UTM equipment according to KS T 1028. After compressing a tape with a width of 25 mm to the SUS304 adherend using a rubber roller (load of 2.0 kg), it was allowed to stand at room temperature for 30 minutes, and then the 180° peel value was measured at a speed of 300 mm/min.

Dispersibility was measured by diluting the pressure-sensitive adhesive composition to a concentration of 10% using ethyl acetate, coating it on a 50 μm PET film, and then drying it, and checking the presence or absence of re-agglomeration of carbon black under a 200-fold magnification optical microscope.

The results are shown in Table 3.

Example 1 Example 2 Example 3 Comparative Example 1 dispersibility ○ ○ ○ × Adhesion at room temperature
(gf/25㎜) 1396 1312 1359 1285

In addition, the results of measuring the dispersibility with an electron microscope are the same as those shown in FIG. 1 . Looking at the results of FIG. 1, when an ester bond is formed in the main chain of the resin constituting the adhesive including monofunctional carboxylic acid ester and/or unsaturated dicarboxylic acid diester, a state diluted with a solvent without adding a dispersant It can be confirmed that the re-agglomeration of the pigment does not occur even in FIG. However, in the case of Comparative Example 1, re-agglomeration of the pigment was found to occur.

Although the present invention has been described with preferred embodiments as described above, it is not limited to the above embodiments, and various modifications and modifications can be made by those skilled in the art within the scope of not departing from the spirit of the present invention. Change is possible. Such modifications and variations are intended to fall within the scope of this invention and the appended claims.

Claims (5)

A pressure-sensitive adhesive composition consisting of acrylic syrup, colorant, photopolymerization initiator, and crosslinking agent and not containing a solvent,
The acrylic syrup includes a monomer selected from monofunctional carboxylic acid esters and unsaturated dicarboxylic acid diesters,
A pressure-sensitive adhesive composition having excellent pigment dispersibility, characterized in that it is prepared through bulk polymerization using a thermal initiator.
The method of claim 1,
The monofunctional carboxylic acid ester is 2-(meth)acryloyloxy ethyl succinate, 2-methacryloyloxy propyl succinate, 4-methacryloxy 4-(meth)acryloyloxy butyl succinate, 2-(meth)acryloyloxy ethyl phthalate, 2-(meth)acryloyloxy propyl phthalate, 4 -methacryloxy butyl phthalate (4-(meth)acryloyloxy butyl phthalate, 2-methacryloyloxy ethyl terephthalate (2-(meth)acryloyloxy ethyl terephthalate), 4-methacryloxy butyl terephthalate (4-(meth)acryloyloxy butyl terephthalate), 2-(meth)acryloyloxy ethyl terephthalate, 2-(meth)acryloyloxy ethyl hexahydro phthalate, 2-methacryloxy propyl hexahydro 2-(meth)acryloyloxy propyl hexahydro phthalate, 4-(meth)acryloyloxy butyl hexahydro phthalate, 2-acryloyloxyethyl -2-hydroxyethyl phthalate), wherein the pressure-sensitive adhesive composition has excellent pigment dispersibility.
The method of claim 1,
The unsaturated dicarboxylic acid diester is dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, diethyl fumarate, Dibutyl fumarate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, methyl ethyl fumarate, methyl butyl fumarate ), and methyl ethyl itaconate.
The method of claim 1,
The monomer is contained in the range of 2 to 30% by weight based on the total weight of the acrylic syrup, and the colorant is contained in the range of 4 to 10% by weight based on the total weight of the acrylic syrup, characterized in that the pigment dispersibility Excellent adhesive composition.
A pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive composition according to claim 1.

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