KR101177912B1 - Pressure sensitive adhesive composition with excellent reliability and absorbability of ultraviolet - Google Patents

Abstract

The present invention relates to a pressure-sensitive adhesive composition having excellent reliability and ultraviolet absorbance, and more particularly, transmittance of 90% or more, haze of less than 1%, and transmittance of less than 3% when measuring UV Visible Spectrometer at a wavelength range of 380 nm or less. Excellent transparency and UV absorption, excellent heat and moisture resistance, very little change due to heat and moisture, excellent reliability as an adhesive, and excellent reliability and UV absorption which can be manufactured relatively simply and economically. It relates to a pressure-sensitive adhesive composition provided.

Adhesive, UV absorber, pressure sensitive, transmittance, heat and moisture resistance

Description

PRESSURE SENSITIVE ADHESIVE COMPOSITION WITH EXCELLENT RELIABILITY AND ABSORBABILITY OF ULTRAVIOLET}

The present invention relates to a pressure-sensitive adhesive composition having excellent reliability and ultraviolet absorbance, and more particularly, transmittance of 90% or more, haze of less than 1%, and transmittance of less than 3% when measuring UV Visible Spectrometer at a wavelength range of 380 nm or less. Excellent transparency and UV absorption, excellent heat and moisture resistance, very little change due to heat and moisture, excellent reliability as an adhesive, and excellent reliability and UV absorption which can be manufactured relatively simply and economically. It relates to a pressure-sensitive adhesive composition provided.

In general, a plasma display panel (PDP) is composed of a discharge gas such as neon, argon, xenon, etc. encapsulated between transparent electrodes printed on a glass tube, and uses a phenomenon of emitting light by gas discharge between electrodes. Or it is advantageous to form a large screen compared to LCD. However, this PDP generates a lot of electromagnetic waves, ultraviolet rays and near-infrared rays. When light is emitted from red, green, and blue trichromatic phosphors, strong visible light is generated in the range of 580 to 590 nm. The presence of additional equipment is essential.

Accordingly, Japanese Patent Application Laid-Open No. 1983-153904 has proposed a PDP using a method of attaching a filter capable of absorbing light of a specific wavelength to the front surface of the PDP in order to correct the color balance of the display color. As a method for blocking harmful light and correcting PDP screen color using such a filter, Japanese Laid-Open Patent Publication No. 1999-160532 discloses a method of separately forming a resin layer containing a near-infrared absorber for color correction on a substrate. Patent No. 2000-340985 discloses a method for controlling the concentration thereof by including a color correction pigment in a transparent adhesive used for bonding members of a PDP filter. In addition, Japanese Patent Laid-Open No. 2001-343520 uses a method of directly dispersing a pigment for coloring a dye in a resin or an adhesive to be applied for improving mesh transparency.

However, these color correction materials may lose reliability due to external UV waves, and for this reason, there is a need for a material that protects workability and required properties, including a UV absorber inside the pressure-sensitive adhesive. to be.

In addition, PDP is exposed to various environments as a display material, and in particular, the material using the pressure-sensitive adhesive proposed in the present invention is generally attached to the outermost surface of the transparent glass of the PDP. There is a problem that is easy to receive.

Since conventional pressure-sensitive adhesives do not have a UV absorbing function, they have a limit in protecting color correction materials such as pigments and dyes from UV rays. In particular, when using a multilayer optical film, such a function is required more.

Typical applications of pressure sensitive adhesives with added UV absorption can be used in optical filters of PDPs. Such a UV absorbent pressure-sensitive adhesive is desirable to have a property that is maintained without being destroyed by sunlight, ultraviolet light or a humidified environment. In particular, the composition used in the optical filter is weak in durability and often loses its function when exposed to heat, direct sunlight, moisture, there is a limit to the type of resin for the adhesive, coating method and the like can be used. In particular, with the explosive growth of the PDP market, requirements for optical properties and durability of the filters used therein are becoming increasingly demanding.

The present invention has been made to solve the above problems, an object of the present invention exhibits a transmittance of less than 3% when measuring UV Visible Spectrometer in the wavelength range of more than 90%, Haze less than 1%, 380nm or less, The present invention provides a pressure-sensitive adhesive composition having excellent reliability and ultraviolet absorbency, which is excellent in transparency and ultraviolet absorbency and excellent in heat and moisture resistance and very little change due to heat or moisture.

It is also an object of the present invention to provide a pressure-sensitive adhesive composition having excellent reliability and ultraviolet absorbency, which can be produced relatively simple and economical.

Pressure sensitive adhesive composition having excellent reliability and ultraviolet absorbency according to the present invention for achieving the above object is a pressure-sensitive adhesive comprising a UV absorber for absorbing light in the region of 380nm or less, UV transmittance of 3% or less in the region of 380nm It is less than, characterized in that it comprises 0.05 to 0.25 parts by weight and 3 to 10 parts by weight of a hydroxyphenylbenzotriazole-based UV absorber with respect to 100 parts by weight of the acrylic copolymer.

Preferably, the pressure-sensitive adhesive is characterized in that the total Haze is 1% or less and the total transmittance is 90% or more.

Hereinafter, the present invention will be described in detail with reference to examples of the present invention. It is to be understood by those skilled in the art that these embodiments are only for describing the present invention in more detail and that the scope of the present invention is not limited by these embodiments in accordance with the gist of the present invention .

The present invention relates to a filter material for protecting color pigments caused by external light in a PDP, and more particularly to a filter material for PDP comprising a transparent substrate containing a color correction function for absorbing light in the visible light region. The present invention relates to a pressure-sensitive adhesive composition having excellent reliability and ultraviolet absorbency.

Examples of the pressure-sensitive adhesives examined in the pressure-sensitive adhesive composition with excellent reliability and ultraviolet absorbency according to the present invention include natural rubber, synthetic rubber, styrene block copolymer, polyvinyl ether, poly (meth) acrylate (acrylic) Pressure-sensitive adhesives, including those based on rate and methacrylate), polyolefins and silicones and having the following general properties. These features include (1) aggressive and permanent viscosity, (2) adhesion to the substrate at a constant pressure, (3) sufficient ability to remain on the attachment, and (4) sufficient adhesion to remove it cleanly from the attachment. It is.

The pressure sensitive adhesive component may be a single pressure sensitive adhesive or may be a combination of two or more pressure sensitive adhesives. Optically clear pressure sensitive adhesives are generally acrylate-based pressure sensitive adhesives. However, silicone based pressure sensitive adhesives, rubber resin based pressure sensitive adhesives, block copolymer based adhesives, in particular those containing hydrogenated elastomers, or vinyl ether polymer based pressure sensitive adhesives may also have optical transparency.

Useful alkyl acrylates (ie, acrylic acid alkyl ester monomers) include linear or branched monofunctional unsaturated acrylates or methacrylates of non-tertiary alkyl alcohols having 4 to 14, especially 4 to 12 carbon atoms, alkyl groups. do.

In a possible embodiment, the pressure sensitive adhesive is based on one or more poly (meth) acrylates (eg, (meth) acrylic acid pressure sensitive adhesives). Poly (meth) acrylic acid pressure sensitive adhesives are, for example, one or more alkyl (meth) acrylate ester monomers such as isooctyl acrylate, isononyl acrylate, 2-methyl-butyl acrylate, 2-ethyl n-hexyl acrylate and n-butyl acrylate, isobutyl acrylate, hexyl acrylate, n-octyl acrylate, n-octyl methacrylate, n-nonyl acrylate, isoamyl acrylate, n-decyl acryl Rate, isodecyl acrylate, isodecyl methacrylate, isobornyl acrylate, 4-methyl-2-pentyl acrylate and dodecyl acrylate and one or more optical co-monomer components such as (meth) Acrylic acid, vinyl acetate, N-vinyl pyrrolidone, (meth) acrylamide, vinyl esters, fumarates, styrene macromers, alkyl maleates and alkyl fumarates (each, Based on maleic acid and fumaric acid), or combinations thereof. Under certain conditions, the poly (meth) acrylic acid pressure sensitive adhesive may comprise about 0 to about 30 weight percent acrylic acid and about 100 to about 70 weight percent one or more isooctyl acrylate, 2-ethyl-hexyl acrylate or n-butyl acrylic Derived from the rate composition.

One particular pressure-sensitive adhesive of the present invention has a state of about 2 to about 10 weight percent acrylic acid and about 90 to about 98 weight percent one or more isooctyl acrylate, 2-ethyl-hexyl acrylate or n-butyl acrylate composition Derived from. One particular state of the pressure sensitive adhesives of the present invention is derived from about 2 to about 10 weight percent acrylic acid and about 90 to about 98 weight percent isooctyl acrylate. Additional conditions include about 70% by weight phenoxy ethyl acrylate and about 25 to about 30% by weight isooctyl acrylate. The condition may further comprise about 1 to about 5 weight percent acrylic acid.

On the other hand, the pressure sensitive adhesive may be viscous in nature. If desired, thickeners may be added to the base material to form pressure sensitive adhesives. Useful thickeners include, for example, rosin ester resins, aromatic hydrocarbon resins, aliphatic hydrocarbon resins and terpene resins. Examples of other materials, including other additives, include oils, plasticizers, antioxidants, ultraviolet ('UV') stabilizers, hydrogenated butyl rubbers, pigments, curing agents, polymer additives, thickeners, chain transfer agents and their pressure sensitive adhesives. If it does not reduce the optical transparency of the, it can be added for a specific purpose.

In order to apply the pressure-sensitive adhesive according to the present invention to the film applicable to the PDP filter, the wet coating method is preferable, and the method of dividing the main material and the curing agent is more preferable for ease of workability and storage stability. You can do it. In addition, what is required in the present invention among these adhesives is a solution to composition and quantitative selection for adhesives having excellent heat and moisture resistance properties.

The ultraviolet absorbent used in the pressure-sensitive adhesive composition having excellent reliability and ultraviolet absorbency according to the present invention is intended to absorb light in an area of 380 nm or less, which is a UV region. When a wavelength of 380 nm or less is scanned into the PDP filter, the color tone dye or pigment may be deformed to deteriorate the durability of the PDP. In addition, if the UV absorber that satisfies this is not properly used, the overall transmittance decreases or the haze rises, thereby degrading the function of the display which is the original purpose of the PDP. If the transmittance in the region of 380nm or more is lowered, visible light may be damaged and color reproducibility may be lowered, resulting in deterioration of product quality. At this time, when the transmittance of 3% or more was not able to sufficiently protect the internal structure, to solve this problem when the transmittance of 7% or less by UV absorbers, more preferably 3% or less when showing Experimental results show that the structure of the PDP can be protected and the objective of selective transmission in the static region can be achieved.

In addition, if the haze is higher than 1.5% due to the UV absorber used, or less than 85% due to the low total transmittance, the screen of the display is uneven and the eyes are easily tired, or there is a loss of color. Sharpness is impaired, which causes deterioration of product quality. Therefore, the researchers have shown that the optical properties due to the UV absorbers used, especially when Haze shows less than 1.5%, more preferably less than 1.0%, and the overall transmittance is more than 85%, more preferably more than 90% I found that it implements.

The stabilization mechanism of the UV stabilizer used at this time is shown in the following two ways. First, a method of blocking ultraviolet energy, selectively absorbing ultraviolet energy and releasing it as other forms of energy that are not harmful to the polymer material, or suppressing the photolysis initiation reaction by suppressing chromophore of the activated polymer material. Light blocking agents, ultraviolet absorbers, etc. belong to this. Second, radical scavengers, peroxide decomposers, hindered amine stabilizers, etc. are included as a method of inhibiting photolytic growth reactions by reacting with free radicals or hydrogen peroxide to stop free radicals and decomposing peroxides during photodegradation.

UV stabilizers generally used include hydroxy benzophenone series and hydroxyphenyl benzotriazole series. Although benzophenone UV stabilizers have excellent compatibility with resins and are used in various ways, UV absorbing ability of 340 nm or more is inferior to benzotriazole UV stabilizers. Benzotriazole-based UV stabilizers have the ability to absorb over a wide range and are mainly used for colorless and high-end products. In addition, there are ultraviolet absorbers such as resorcinol monobenzoate, salicylate, hydroxy benzoate and formamidine. Free radical capture also captures free radicals, which are the mediators of oxidation, in contrast to the previously described methods of eliminating energy sources. Typical UV stabilizers by free radical capture are hindered amines (HALS), which are easily oxidized to be converted to nitrooxy radicals and react with polymeric radicals to produce hydroxyamine ethers. Unlike UV absorbers, hindered amine UV stabilizers have excellent surface protection and can be applied to products with thin cross-sections. In addition, a cyclic imino ester compound having two carbon atoms constituting an aromatic nucleus and an imino ester ring as disclosed in US Pat. No. 4,446,262 may be used as an ultraviolet stabilizer. Imino ester UV stabilizers have been reported to have excellent thermal and oxidative stability.

As shown in the following experiment, it is difficult to maintain the appearance quality as the amount of UV absorber increases, and it is also shown that the quantitative selection is important according to the type of UV absorber. When prepared using randomized generalized pressure sensitive adhesives and UV absorbers described above, the visibility is poor, or it is difficult to show selective transmittance. Therefore, a pressure-sensitive adhesive having excellent transparency and visibility having a total transmittance of 90% or more and a transmittance of less than 3% and a selective transmittance of less than 3% and a haze of 1% or less in a wavelength band of 380 nm or less is a technical problem in the present invention. Solution to UV Absorbers and Quantitative Selection for Manufacturing

[Example]

Example 1

Polyacrylate pressure-sensitive adhesive is 0.2 parts by weight of epoxy curing agent based on 100 parts by weight of acrylic copolymer with respect to acrylic copolymer, and 8 parts by weight of Hydroxyphenyl -benzotriazole UV absorber based on 100 parts by weight of acrylic copolymer. For example, an adhesive composition to which Octyl-3- [3- tert- butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate was added was used.

[Example 2]

The polyacrylate pressure sensitive adhesive used an epoxy-based curing agent 0.05 parts by weight based on 100 parts by weight of an acrylic copolymer, and 8 parts by weight of a hydroxyphenyl -benzotriazole-based UV absorber based on 100 parts by weight of an acrylic copolymer. The adhesive composition to which 2-Ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate was added was used.

Comparative Example 1

Polyacrylate pressure-sensitive adhesive is 0.2 parts by weight of 100 parts by weight of acrylic copolymer, 100 parts by weight of acrylic copolymer, isocyanate curing agent having at least 3 functional groups derived from toluene diisocyanate for acrylic copolymer. Adhesive by weight of Hydroxyphenyl -benzotriazole UV absorber by weight, more specifically Octyl-3- [3- tert -butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate The composition was used.

Comparative Example 2

Polyacrylate pressure-sensitive adhesive used 0.05 part by weight of isocyanate curing agent having 3 or more functional groups derived from toluene diisocyanate with respect to 100 parts by weight of acrylic copolymer with respect to acrylic copolymer, and 7 parts by weight of hydroxyphenyl with respect to acrylic copolymer. -benzotriazole UV absorber, more specifically, 2-Ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate Was used.

[Comparative Example 3]

The polyacrylate pressure-sensitive adhesive was used 0.05 part by weight of 100 parts by weight of an acrylic copolymer, an isocyanate-based curing agent having three or more functional groups derived from toluene diisocyanate, and 100 parts by weight of an acrylic copolymer. By weight of Hydroxyphenyl -benzotriazole-based UV absorber, more specifically Phenol, 2- (5-chloro-2H-benzotriazole-2-yl) -6- (1,1-dimethylethyl) -4-methyl It was.

[Comparative Example 4]

The polyacrylate pressure sensitive adhesive used an epoxy-based curing agent 0.3 parts by weight based on 100 parts by weight of an acrylic copolymer, and 7% by weight of a hydroxyphenyl-triazine UV absorber based on 100 parts by weight of an acrylic copolymer. Preferably, an adhesive composition to which 2,4-Bis (2-hydroxy-4-butyloxyphenyl) -6- (2,4-bis-butyloxyphenyl) -1,3,5-triazine was added was used.

After the addition of Solvent (MEK, Toluene, etc.) for the coating of the composition according to Examples 1 to 2 and Comparative Examples 1 to 4 wet coating on a 100㎛ PET Film and dried, an adhesive having a thickness of 20㎛ The film was dried for 1 week at room temperature for 7 days to measure the described physical properties. Before measuring the physical properties, the surface was protected with a release film to prevent contamination of the pressure-sensitive adhesive.

As a result of coating experiment, data on transmittance, Haze and transmittance below 380nm and coating appearance are shown in Table 1.

[Table 1]

division Transmittance Haze Less than 380nm
Transmittance coating
Exterior Overall rating Example 1 90.72 0.37 2.95 ○ ○ Example 2 90.38 0.18 3.00 ○ ○ Comparative Example 1 91.20 0.39 3.36 △ △ Comparative Example 2 90.89 0.23 3.16 ○ ○ Comparative Example 3 91.02 0.70 4.98 ○ ○ Comparative Example 4 90.46 0.89 4.37 △ △

As can be seen in Table 1, in Example 1, Example 2, Comparative Example 2, Comparative Example 3, Comparative Example 4, the adhesive component excellent in all of the transmittance, haze, 380nm or less transmittance and appearance were obtained. In Comparative Example 1, the appearance was poorer than other samples.

The coated film was dried for 7 days at room temperature for 1 week to evaluate the high temperature and humidity reliability of the sample subjected to the coating experiment. For the high temperature and humidity evaluation, the sample was attached to the glass surface and left for 500 hours in a constant temperature and humidity environment with a temperature of 60 ° C and a humidity of 90%.

Data on the high temperature and humidity reliability evaluation results of the prepared samples are shown in Table 2.

[Table 2]

division Coating
Overall rating Uplifting Appearance change Overall rating Example 1 ○ ○ ○ ○ Example 2 ○ ○ ○ ○ Comparative Example 1 △ △ △ △ Comparative Example 2 ○ X ○ X Comparative Example 3 ○ X △ X Comparative Example 4 △ △ X X

As shown in Table 2, the result of the reliability evaluation was determined that Comparative Example 1 was not as good as the Example sample in terms of lifting and appearance. Also, in Comparative Example 2, the lifting phenomenon was severely judged to be unsuitable. In Comparative Example 3, a phenomenon in which spots occurred due to changes in appearance in addition to the lifting phenomenon was observed. In Comparative Example 4, weak lifting and spots were observed. As shown in the results of the reliability evaluation, the cause of the lifting was a result of the amount and type of the curing agent. When the epoxy was used as the curing agent, it was confirmed that the heat and moisture resistance properties were excellent. In particular, the use of isocyanate-based curing agent was able to secure some reliability by quantitative adjustment. However, when a large amount of curing agent was used, the appearance was reduced when coating. In addition, the appearance change of the reliability evaluation was a result of the type and amount of UV absorber, and thus Octyl-3- [3- tert- butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate Two kinds of UV absorbers with, 2-Ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate are considered to have good results. . In particular, when using 2,4-Bis (2-hydroxy-4-butyloxyphenyl) -6- (2,4-bis-butyloxyphenyl) -1,3,5-triazine UV absorber, the appearance change after reliability evaluation appeared.

[Experimental Example]

Transmittance and Hayes  exam

Permeability and haze of all samples were measured using a Haze meter (NDH-300A). Given that the results of this experiment described are fabricated in a laboratory, anyone in this field expects that the production in the actual process will result in better appearance quality compared to the results in this experiment in the actual process. You can do it.

UV characteristic evaluation

In the evaluation of the UV characteristics in the region of 380 nm or less of all samples, the transmittance in the region of 380 nm or less was measured using a UV Visble Spectrometer (Shimadzu, Japan).

Optical property test (reference)

The optical properties of the base as a reference point when the base PET was used in the laminate were tested for luminous transmittance and haze. In addition, the water absorption and gas permeability of the general PET film were measured. These values are shown in Table 3.

[Table 3]

materials Luminous transmittance (%) Haze (%) Water absorption rate (%) Gas transmittance
(g / m ² /24hrs/0.1mm) PET 89.0 0.8 0.4 6.9

High temperature and humidity test

The high temperature and humidity evaluation is made by attaching the sample cleanly to the glass surface to avoid bubbles or other foreign substances at 2 Kg pressure, and leaving it above 500Hr in a constant temperature and humidity environment with a temperature of 60 ° C and a humidity of 90%. It was.

In the present specification, the present inventors describe only a few examples of various manufacturing and analysis experiments performed according to the manufacturing method according to the present invention, but the technical idea of the present invention is not limited thereto and is variously modified by those skilled in the art. Of course it can be implemented.

As described above, the pressure-sensitive adhesive composition having excellent reliability and ultraviolet absorbency according to the present invention has a transmittance of 90% or more, a haze of less than 1%, and a transmittance of less than 3% when measuring the UV Visible Spectrometer at a wavelength range of 380 nm or less. It has the characteristics of transparency, UV absorption, excellent heat and moisture resistance, and very little change by heat and moisture, so it has the effect of excellent reliability as an adhesive.

In addition, it can be seen that the pressure-sensitive adhesive composition having excellent reliability and ultraviolet absorbency according to the present invention has a relatively simple and economical effect.

Claims (2)

In the pressure-sensitive adhesive composition having excellent reliability and ultraviolet absorbency, A pressure-sensitive adhesive comprising a UV absorber that absorbs light in the region of 380 nm or less, wherein the UV transmittance in the region of 380 nm or less is less than 3%, and the pressure-sensitive adhesive is an epoxy-based curing agent based on 100 parts by weight of an acrylic copolymer. 0.05 to 0.25 parts by weight and 3 to 10 parts by weight of a hydroxyphenylbenzotriazole (Hydroxyphenylbenzotriazole) UV absorber, The hydroxyphenylbenzotriazole (Hydroxyphenylbenzotriazole) -based UV absorbing agent octyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] prop Cypionate or 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate, The pressure-sensitive adhesive is a pressure-sensitive adhesive composition with excellent reliability and ultraviolet absorption, characterized in that the overall haze (Haze) is 1% or less and the total transmittance is 90% or more. delete