KR102102786B1 - Optically clear adhesive composition, optically clear adhesive film and dual sided adhesive tape - Google Patents

Abstract

100 parts by weight of an acrylic photocurable resin; 0.01 to 10 parts by weight of a photoinitiator; And it provides a composition for an optically transparent pressure-sensitive adhesive containing; 0.01 to 1 part by weight of a high temperature crosslinkable compound.

Description

Optical transparent adhesive composition, optical transparent adhesive film and double-sided adhesive tape {OPTICALLY CLEAR ADHESIVE COMPOSITION, OPTICALLY CLEAR ADHESIVE FILM AND DUAL SIDED ADHESIVE TAPE}

It relates to a composition for an optically transparent adhesive, an optically transparent adhesive film, and a double-sided adhesive tape.

In recent years, electronic devices such as PDAs, mobile communication terminals, or car navigation systems have formed a large market. In such an electronic device, the technical goals pursued mainly include thinning, lightening, low power consumption, high resolution, and high brightness.

In the electronic device, a touch screen panel is installed on an input manipulation unit. The touch screen panel is made of a multi-layer structure including the outermost cover window layer, and is formed by laminating using an optical adhesive sheet.

The optical adhesive sheet is optically transparent, and various physical properties such as touch sensitivity and durability are required.

One embodiment of the present invention provides a composition for an optical transparent pressure-sensitive adhesive that can implement a pressure-sensitive adhesive exhibiting excellent repulsion resistance and excellent high-temperature retention at high temperatures.

Another embodiment of the present invention provides an optically transparent adhesive film prepared from the composition for optically transparent adhesive.

Another embodiment of the present invention provides a double-sided adhesive tape using an optically transparent adhesive film prepared from the composition for optically transparent adhesive.

In one embodiment of the present invention, 100 parts by weight of an acrylic photocurable resin; 0.01 to 10 parts by weight of a photoinitiator; And it provides a composition for an optically transparent pressure-sensitive adhesive containing; 0.01 to 1 part by weight of a high temperature crosslinkable compound.

In another embodiment of the present invention, there is provided a transparent adhesive film for optics comprising a photocurable product of an acrylic photocurable resin and a high temperature crosslinkable compound.

In another embodiment of the invention, the transparent substrate; And a transparent adhesive film for optics formed on both sides of the transparent substrate. The transparent adhesive film for optics provides a double-sided adhesive tape comprising a photocured product of an acrylic photocurable resin and a high temperature crosslinkable compound.

The optically transparent adhesive film prepared from the composition for optically transparent adhesives exhibits excellent repulsion resistance at high temperatures and excellent high temperature retention properties.

1 schematically illustrates a cross-section of a double-sided adhesive tape according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail. However, this is provided as an example, and the present invention is not limited thereby, and the present invention is only defined by the scope of claims to be described later.

In the drawings of the present specification, the thickness is enlarged to clearly express various layers and regions. In the drawings, thicknesses of some layers and regions are exaggerated for convenience of description.

In the following, the "top (or bottom)" of the substrate or the "top (or bottom)" of the substrate to form an arbitrary configuration means that any configuration is formed in contact with the top (or bottom) of the substrate. No, it is not limited to not including other configurations between the substrate and any configuration formed on (or under) the substrate.

In one embodiment of the invention,

100 parts by weight of an acrylic photocurable resin;

0.01 to 1 part by weight of photoinitiator; And

It provides a composition for an optically transparent pressure-sensitive adhesive comprising; 0.01 to 1 part by weight of a high temperature crosslinkable compound.

The optical transparent adhesive film may be photocured to prepare an optical transparent adhesive film. A part of the high temperature crosslinkable compound may crosslink during photocuring of the composition for optically transparent adhesive, but at least some may be included in the optically transparent adhesive film without crosslinking. The high temperature crosslinkable compound in a state in which the crosslinking reaction is not performed may crosslink with the acrylic photocurable resin in the optical transparent adhesive film when the optically transparent adhesive film is placed in a high temperature environment. Accordingly, the optically transparent adhesive film is capable of exhibiting high resilience resistance and excellent high temperature retention properties at high temperatures.

Repulsion resistance refers to a property in which an adhesive film provides a buffering action to a product having a property to be bent, and serves to hold the product so that it does not bend. For example, if the mobile phone is said to have excellent repulsion resistance, it can prevent the air bubbles between the back cover and the glass of the mobile phone from filling under high temperature and high humidity in a living environment such as a sauna, and reduce damage to the product.

Excellent heat retention means that the product containing the adhesive film is placed in a high temperature environment, but the adhesive film does not collapse due to the high temperature, and the product has the power to stick well even in harsh environments. Means

The optically transparent adhesive film is optically transparent and is suitable for application to displays applied to electronic devices such as mobiles. In addition, as the display is diversified in use in automobiles, various household appliances, etc., in addition to mobiles, the display requires adhesive properties and reliability for high-temperature environments for adhesive films applied in the case of automobiles.

The optically transparent gradual film prepared from the composition for optically transparent adhesives can be effectively applied to applications requiring adhesive properties and reliability for high-temperature environments, such as in automobiles.

The acrylic photocurable resin, specifically, (meth) acrylic acid ester-based monomer; And a crosslinkable monomer comprising at least one selected from the group consisting of a hydroxy group-containing monomer, a carboxyl group-containing monomer or a nitrogen-containing monomer, and combinations thereof. The photopolymerizable mixed monomer component may be a copolymerized resin.

The optical transparent adhesive composition may include the acrylic photocurable resin in a high molecular weight prepolymer form, and in addition, may further include an unreacted monomer or oligomer form of the mixed monomer.

The (meth) acrylic acid ester monomer is, for example, an alkyl (meth) acrylate, and the alkyl of the alkyl (meth) acrylate may be linear or branched C1-C14 alkyl. Using the alkyl (meth) acrylate of the carbon number in the above range, the photocured product of the acrylic photocurable resin may be adjusted to have appropriate cohesive force, glass transition temperature, and adhesive properties.

Specifically, the (meth) acrylic acid ester monomer is methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate , t-butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, n-octyl ( Meth) acrylate, isooctyl (meth) acrylate, isobornyl (meth) acrylate, isononyl (meth) acrylate, and combinations thereof.

Specifically, the crosslinkable monomer is 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) Acrylate, 8-hydroxyoctyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, 2-hydroxypropylene glycol (meth) acrylate, acrylic acid, methacrylic acid, 2- (meth) acrylic Loyloxy acetic acid, 3- (meth) acryloyloxy propyl acid, 4- (meth) acryloyloxy butyric acid, acrylic acid duplex, itaconic acid, maleic acid, 2-isocyanatoethyl (meth) acrylic Rate, 3-isocyanatopropyl (meth) acrylate, 4-isocyanatobutyl (meth) acrylate, (meth) acrylamide, N-vinyl pyrrolidone, N-vinyl caprolactam, and combinations thereof It may include one selected from the group consisting of.

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The acrylic photocurable resin may have a weight average molecular weight of 1,000,000 to 3,000,000 g / mol.

The type of the photoinitiator is not particularly limited as long as it generates a radical by light irradiation and can initiate a polymerization reaction, and for example, benzoin-based initiators, hydroxy-ketone-based initiators, amino ketone-based initiators, and caprolactam initiators And combinations thereof.

The photoinitiator may be used in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the acrylic photocurable resin. The optically transparent adhesive composition may include an optical initiator of the above content, to prepare an optically transparent adhesive film to have an appropriate level of curing. The appropriate level of curing may be specifically 0.01 to 1%. The optically transparent adhesive film manufactured to have an appropriate level of curing can improve adhesion to an adhesion target.

Curing degree can be measured by the following formula (1).

<Calculation formula 1>

Curing degree (GEL,%) = (later mass / initial mass) × 100

In Equation 1, the mass of the target cured product to measure the degree of curing is measured to obtain the 'first mass'. The mass (dry mass) of the specimen obtained by immersing the specimen of the cured product of the first weight in ethyl acetate solvent and leaving it at room temperature for 24 hours, after filtering using 200 mesh wire, and drying the remaining specimen at 110 ° C. for 2 hours Let's say 'later mass'.

As described above, the high-temperature crosslinkable compound may be used without limitation as long as it is a compound capable of crosslinking reaction with the acrylic photocurable resin or its cured product by heat at a high temperature, for example, 60 ° C. or higher. The high temperature crosslinkable compound may be partially crosslinked with the acrylic photocurable resin by light during the process of preparing a transparent adhesive film for optics by photocuring the composition for optically transparent adhesive, but at least some or most It is contained in the transparent adhesive film for optics, while maintaining a reaction point without exhausting in a state without crosslinking reaction. When the optically transparent adhesive film is placed in a high temperature environment, for example, 60 ° C. or higher, a crosslinking reaction may proceed at a reaction point of the high temperature crosslinkable compound. The optically transparent adhesive film further improves repulsion resistance as the additional crosslinking reaction proceeds in a high temperature environment, and also improves high temperature holding power characteristics. The optically transparent adhesive film may have a relatively low cure degree in a state in which the high temperature crosslinkable compound is not crosslinked, thereby having high adhesion properties to a material to be adhered, and thus high adhesion to a substrate to a substrate. At the same time, the optically transparent adhesive film can exhibit excellent repulsion resistance and excellent high temperature retention properties when placed in a high temperature environment.

Specifically, the high temperature crosslinkable compound may include one selected from the group consisting of melamine compounds, aziridine compounds, epoxy compounds, isocyanate compounds, metal chelate compounds, and combinations thereof.

The high-temperature cross-linkable compound is more polyfunctional, that is, the higher the functional group content, the more the reaction point at high temperature, the higher the physical properties.

For example, the melamine-based compound may be a trifunctional melamine compound containing three melamine groups, a six-functional melamine compound containing six, or the like.

The melamine-based compound, specifically, may be used one selected from the group consisting of methoxymethylmelamine, butoxymethylmelamine, ethoxymethylmelamine, and combinations thereof.

The optically transparent adhesive film obtained by photocuring the composition for optically transparent adhesive contains the high temperature crosslinkable compound, for example, the high temperature crosslinkable compound is methoxymethylmelamine, butoxymethylmelamine, ethoxymethyl In the case of melamine containing an alkoxy group such as melamine, when the optically transparent adhesive film is elevated in a high temperature environment, the ester group of the acrylic photocurable resin and the alkoxy group of the melamine compound may crosslink.

The aziridine-based compound is N, N'-toluene-2,4-bis (1-aziridinecarboxamide), N, N'-diphenyl methane-4,4'-bis (1-aziridinecarboxamide) ), Triethylene melamine, bisisopropaloyl-1- (2-methylaziridine) and tri-1-aziridinylphosphine oxide.

The isocyanate-based compound is tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoform diisocyanate, tetramethylxylene diisocyanate, naphthalene diisocyanate, and any one of the polyols (ex. Trimethyl Roll propane) may also be composed of one or more trout selected from the group consisting of reactants.

The epoxy compounds include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N, N, N ', N'-tetraglycidyl ethylenediamine and glycerin diglycidyl ether. It may be composed of at least one selected from the group consisting of.

The metal chelating compound may be a compound in which a polyvalent metal such as aluminum, iron, zinc, tin, titanium, antimony, magnesium, and / or vanadium is coordinated with acetyl acetone or ethyl acetoacetate, but is not limited thereto.

In one embodiment, the high temperature crosslinkable compound may be an aziridine-based compound. Since the aziridine-based compound has a relatively low activation temperature, it may be advantageous for realizing high temperature properties.

The high temperature crosslinkable compound may be included in the composition for optical transparent pressure sensitive adhesive in an amount of 0.01 to 1 part by weight, specifically 0.1 to 0.3 part by weight, based on 100 parts by weight of the acrylic photocurable resin. The optical transparent adhesive composition may exhibit high resilience and high temperature retention properties in a high-temperature environment, including the above-mentioned high-temperature crosslinkable compound.

In addition, the composition for the optical transparent pressure-sensitive adhesive is made of an epoxy resin, a crosslinking agent, a UV stabilizer, an antioxidant, a colorant, a reinforcing agent, a filler, an antifoaming agent, a surfactant, a plasticizer, and combinations thereof, in a range not affecting the effect of the invention It may further include one or more additives selected from the group.

In another embodiment of the present invention, there is provided a transparent adhesive film for optics comprising a photocurable product of an acrylic photocurable resin and a high temperature crosslinkable compound.

The optically transparent adhesive film may be prepared by photocuring the aforementioned optically transparent adhesive composition. Therefore, the detailed description of the acrylic photocurable resin and the high temperature crosslinkable compound is as described above.

As described above, the high-temperature crosslinkable compound contained in the optically transparent adhesive film is included without crosslinking reaction, and may be capable of crosslinking in a high temperature environment of 60 ° C. or higher.

As described above, the optically transparent adhesive film may include 0.01 to 1 part by weight of the high temperature crosslinkable compound, specifically 0.1 to 0.3 part by weight, relative to 100 parts by weight of the acrylic photocurable resin.

As described above, the high temperature crosslinkable compound may include one selected from the group consisting of melamine compounds, aziridine compounds, epoxy compounds, isocyanate compounds, metal chelate compounds, and combinations thereof.

The optically transparent adhesive film may have a curing degree of 50 to 80%.

Calculation of the said hardening degree is based on the above-mentioned calculation formula 1.

The optically transparent adhesive film is manufactured by photo-curing with the above-mentioned curing degree to control the degree of curing and to adjust the peeling force and softness of the adhesive to various point adhesive properties (peeling force, tack, holding force, etc.) Can be excellent. While not containing a high temperature crosslinkable compound, the pressure-sensitive adhesive film prepared to have a curing degree in the above range may be difficult to implement resilience and retention properties at high temperature, but the optically transparent pressure-sensitive adhesive film also controls curing in the above range Even at high temperatures, excellent repulsion resistance and excellent high temperature retention properties can be realized.

The method for curing the composition for optical transparent pressure-sensitive adhesives is not particularly limited, and for example, a curing process may be performed by irradiating ultraviolet rays on the coating layer formed by the composition for optical optical pressure-sensitive adhesives. However, in order not to lose the reaction point of the high-temperature crosslinkable compound, after performing the curing process for the optical transparent pressure-sensitive adhesive composition, the step of aging in a predetermined condition (aging) can be omitted.

The optically transparent adhesive film may be formed on both sides of the substrate to be manufactured as a double-sided adhesive tape.

1 schematically shows a cross-section of a double-sided adhesive tape comprising a transparent adhesive film for optics according to an embodiment of the present invention.

Referring to FIG. 1, the double-sided adhesive tape may have a structure of a transparent substrate 10 and optical transparent adhesive films 20 formed on both sides of the transparent substrate 10, respectively.

The transparent substrate 10 may be a transparent plastic film such as polyethylene terephthalate (PET) film, polycarbonate (PC) film, polyvinyl chloride (PVC) film.

Hereinafter, examples and comparative examples of the present invention will be described. The following examples are only examples of the present invention, and the present invention is not limited to the examples below.

( Example )

Example  One

50 parts by weight of ethylhexyl acrylate, 50 parts by weight of isobornyl acrylate and 2 parts by weight of benzophenone methacrylate (Visiomer 6976, Evonik) were placed in a 1 liter glass reactor and thermally polymerized to obtain an acrylic photocurable resin syrup having a viscosity of 7,000 cP. . 0.3 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (Igacure 184, BASF) as a photoinitiator and trimethylolpropane tris (2-methyl as an aziridine curing agent) with respect to 100 parts by weight of the photocurable acrylic copolymer resin (based on solid content) obtained After mixing 0.3 parts by weight of -1-aziridine propionate) (Trimethylolpropane tris (2-methyl-1-aziridine propionate)), the mixture was sufficiently stirred to prepare a composition for optically transparent adhesive. Subsequently, the composition for a transparent pressure-sensitive adhesive for photocurable optics was formed to a thickness of 100 µm, and light-cured at a wavelength of 250 nm to be photocured to prepare a transparent adhesive film for optics.

Example  2

A transparent adhesive film for optics was prepared in the same manner as in Example 1, except that 0.3 parts by weight of the trifunctional melamine compound (trade name: Cymel327, methyliminomelamine, manufactured by Mitsui Cytec) was used as the high-temperature crosslinkable compound. Methoxymethylated melamine

Example  3

A transparent adhesive film for optics was prepared in the same manner as in Example 1, except that 0.3 parts by weight of the six-functional melamine compound (trade name: Cymel303, manufactured by hexamethoxymethylmelamine Mitsui Cytec) was used as the high-temperature crosslinkable compound.

Comparative example  One

An optically transparent adhesive film was prepared in the same manner as in Example 1, except that a composition for optically transparent adhesive was prepared without adding a high temperature crosslinkable compound.

Comparative example  2

50 parts by weight of ethylhexyl acrylate, 50 parts by weight of isobornyl acrylate and 2 parts by weight of benzophenone methacrylate (Visiomer 6976, Evonik) were placed in a 1 liter glass reactor and thermally polymerized to obtain an acrylic photocurable resin syrup having a viscosity of 7,000 cP. . 0.3 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (Igacure 184, BASF) as a photoinitiator with respect to 100 parts by weight of the photocurable acrylic copolymer resin (based on solid content), trimethylolpropane as an aziridine-based curing agent as a high temperature crosslinkable compound Tris (2-methyl-1-aziridine propionate) (Trimethylolpropane tris (2-methyl-1-aziridine propionate)) After mixing 1.2 parts by weight and sufficiently stirred to prepare a composition for an optically transparent adhesive. The composition for a transparent adhesive for photocurable optics was photocured by irradiating with a light having a wavelength of 250 nm, and then, a heat curing reaction was performed at 60 ° C for 5 minutes to prepare a transparent adhesive film for optics with a thickness of 100 μm.

evaluation

Experimental example  1: Curing degree measurement

For the transparent adhesive films for optics prepared in Examples 1-3 and Comparative Example 1, the degree of curing was measured by the following calculation formula 1.

<Calculation formula 1>

Curing degree (GEL,%) = (later mass / initial mass) × 100

The first mass is obtained by measuring the mass of the target hardened specimen to be measured. The mass (dry mass) of the specimen obtained by immersing the specimen of the cured product of the first weight in ethyl acetate solvent and leaving it at room temperature for 24 hours, after filtering using 200 mesh wire, and drying the remaining specimen at 110 ° C. for 2 hours Let's say 'later mass'.

Experimental example  2: Repulsion resistance  Measure

After preparing a specimen with a size of 150 mm × 20 mm for the optically transparent adhesive film prepared in Examples 1-3 and Comparative Example 1, and then attaching it to one end surface of an aluminum plate (155 mm × 30 mm × 0.5 mm), 7Kg roller Was reciprocated twice. After attaching the aluminum plate to the polycarbonate sheet so that one end of the polycarbonate sheet (170 mm × 35 mm × 2 mm) and one end of the aluminum plate coincide, the 7 kg roller was reciprocated twice. After storing at room temperature for 24 hours, the specimen is placed in a test jig (210mm × 165mm × 5mm) made of aluminum, placed in an 85 ° C / 85% relative humidity chamber, and the specimen of the optical transparent adhesive film between the aluminum plate and the polycarbonate sheet is separated. Table 1 shows the time at the time when it started to occur.

Table 1 below shows the results of the evaluation of the physical properties.

division Curing degree [%] Repulsion resistance
[Hour, hr] Example 1 68 12 Example 2 71 6 Example 3 72 4 Comparative Example 1 52 2 Comparative Example 2 80 0

From the results of Table 1, in Example 1-3, a part of the high temperature crosslinkable compound was crosslinked during photocuring to maintain an appropriate degree of curing compared to Comparative Examples 1 and 3. The higher the degree of curing, the better the high-temperature holding power, and the lower the degree of curing, the better the resilience. Resilience is excellent when the curing degree is 50 to 60. Since Examples 1-3 were used together with a high-temperature crosslinkable compound even though it was outside the curing degree range of 50-60, it was confirmed that it had excellent repulsion resistance.

Since the high temperature crosslinkable compound used in Example 2-3 is activated at a relatively low temperature than the high temperature crosslinkable compound used in Example 1, the high temperature properties of Example 2-3 show better results than Example 1 have.

Although preferred embodiments of the present invention have been described in detail above, the scope of rights of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention defined in the following claims are also provided. It belongs to the scope of the invention.

10: transparent substrate
20: optically transparent adhesive film
100: double-sided adhesive tape

Claims (13)

100 parts by weight of an acrylic photocurable resin;
0.01 to 10 parts by weight of a photoinitiator; And
High temperature crosslinkable compound 0.1 to 0.3 parts by weight; containing,
The high temperature crosslinkable compound is a composition for an optically transparent adhesive, which is a trifunctional melamine compound or a hexafunctional melamine compound.
delete According to claim 1,
The acrylic photocurable resin is a (meth) acrylic acid ester-based monomer; And a crosslinkable monomer comprising at least one selected from the group consisting of a hydroxy group-containing monomer, a carboxyl group-containing monomer or a nitrogen-containing monomer, and combinations thereof.
Composition for optically transparent adhesives.
According to claim 3,
The (meth) acrylic acid ester monomer is an alkyl (meth) acrylate, and the alkyl of the alkyl (meth) acrylate is linear or branched C1-C14 alkyl.
Composition for optically transparent adhesives.
According to claim 3,
The (meth) acrylic acid ester monomer is methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, t- Butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, n-octyl (meth) acrylic Rate, isooctyl (meth) acrylate, isobornyl (meth) acrylate, isononyl (meth) acrylate, and combinations thereof.
Composition for optically transparent adhesives.
According to claim 3,
The crosslinkable monomer is 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8 -Hydroxyoctyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, 2-hydroxypropylene glycol (meth) acrylate, acrylic acid, methacrylic acid, 2- (meth) acryloyloxy acetic acid , 3- (meth) acryloyloxy propyl acid, 4- (meth) acryloyloxy butyl acid, acrylic acid duplex, itaconic acid, maleic acid, 2-isocyanatoethyl (meth) acrylate, 3- From the group consisting of isocyanatopropyl (meth) acrylate, 4-isocyanatobutyl (meth) acrylate, (meth) acrylamide, N-vinyl pyrrolidone, N-vinyl caprolactam, and combinations thereof. Containing the selected one
Composition for optically transparent adhesives.
delete According to claim 1,
The photoinitiator comprises one selected from the group consisting of benzoin-based initiators, hydroxy ketone-based initiators, amino ketone-based initiator caprolactam, and combinations thereof.
Composition for optically transparent adhesives.
A transparent adhesive film for optics comprising a photocurable product of an acrylic photocurable resin and a high temperature crosslinkable compound, wherein the high temperature crosslinkable compound is a trifunctional melamine compound or a 6 functional melamine compound.
delete The method of claim 9,
The high-temperature crosslinkable compound is included without crosslinking, and capable of crosslinking in a high temperature environment of 60 ° C. or higher
Transparent adhesive film for optics.
The method of claim 9,
Curing degree is 0.01 to 1% phosphorus
Transparent adhesive film for optics.
Transparent substrates; And
Optical transparent adhesive film formed on both sides of the transparent substrate;
It is a double-sided adhesive tape containing,
The optically transparent adhesive film includes a photocurable product of an acrylic photocurable resin and a high temperature crosslinkable compound, and the high temperature crosslinkable compound is a trifunctional melamine compound or a six functional melamine compound.

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