KR20140120521A - Cured product composition for optically clear adhesive film, optically clear adhesive film and touch screen panel - Google Patents

Abstract

The present invention relates to a curable composition for an adhesive, an optical adhesive film, and a touch screen panel. More specifically, provided is a curable composition for an adhesive which is cured to have about 80 wt% or more of gel content from a hydroxyl group-containing acrylic resin and a peroxide-based hardener. According to an embodiment of the present invention, an adhesive having excellent durability can be implemented by using the curable composition for the adhesive.

Description

TECHNICAL FIELD [0001] The present invention relates to a curable composition for a pressure-sensitive adhesive, an optical adhesive film, and a touch screen panel,

A curing composition for an adhesive, an optical adhesive film, and a touch screen panel.

2. Description of the Related Art In recent years, electronic devices such as a PDA, a mobile communication terminal, or a navigation system for a vehicle have formed a large market. In such an electronic apparatus, when a touch screen or a touch screen panel is provided on an input operation section, a transparent conductive plastic film is used for lightening and preventing breakage. Examples of the transparent conductive film include a transparent conductive film in which a polyethylene terephthalate (PET) film is used as a substrate and a conductive layer such as indium tin oxide (ITO) is formed on one surface of the transparent conductive film. A conductive glass, a stiffener or a deco film.

In recent years, with the progress of thinning of the optical film, the pressure-sensitive adhesive film used for the touch panel has been demanded to be lightweight and good in workability. The pressure sensitive adhesive used for attaching the transparent conductive film in a touch screen or touch screen panel may have a step absorbency capable of absorbing printed steps by a decoupled film, a curl or bubble when exposed to a severe condition such as a high temperature or high humidity condition, And the like; Cutting ability to suppress punching or pressing at the time of cutting; And physical properties such as excellent adhesiveness and wettability to various substrates are required, and various physical properties such as cohesive strength are required.

One embodiment of the present invention provides a curing composition for a pressure-sensitive adhesive improved in durability.

Another embodiment of the present invention provides an optical adhesive film comprising the curing composition for a pressure-sensitive adhesive.

Another embodiment of the present invention provides a touch screen panel using the optical adhesive film.

In one embodiment of the present invention, there is provided a cured composition for a pressure-sensitive adhesive which is cured to have a gel content of about 80 wt% or more from a hydroxy group-containing acrylic resin and a peroxide curing agent.

The hydroxy group-containing acrylic resin may be obtained by copolymerizing about 0.1 to about 30% by weight of a hydroxyl group-containing monomer in 100% by weight of the sum of monomers copolymerized.

(Meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (Meth) acrylate, 2-hydroxyethyleneglycol (meth) acrylate or 2-hydroxypropyleneglycol (meth) acrylate, and combinations thereof.

The peroxide-based curing agent may have a one-minute half-life temperature of about 70 ° C to about 160 ° C.

The peroxide-based curing agent may include one selected from the group consisting of hydrogen peroxide, ketone peroxide, diacyl peroxide, perester, dialkyl peroxide, and combinations thereof.

The hydroxy group-containing acrylic resin may be a copolymer of a hydroxy group-containing monomer and a meta (acrylic) alkyl ester monomer.

The (meth) acrylic alkyl ester monomer may be selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, Butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl Acrylate, N-acryloylmorpholine (ACMO), 2-hydroxybutyl acrylate (N-acryloxypropyl acrylate) And a combination thereof.

And the cured product may be cured at a ratio of about 0.05 to about 5 parts by weight of the peroxide-based curing agent to 100 parts by weight of the hydroxy-containing acrylic resin.

The curing composition for a pressure-sensitive adhesive may be obtained by curing a mixture obtained by further adding a polyfunctional crosslinking agent, a curing accelerator, or both, to the acrylic resin containing a hydroxyl group and the peroxide-based curing agent.

The curable composition for a pressure-sensitive adhesive may be a pressure-sensitive adhesive having a peeling force of 1600 to 3000 g / in.

In another embodiment of the present invention, there is provided an optical adhesive film comprising a pressure-sensitive adhesive layer formed from the curing composition for a pressure-sensitive adhesive.

The pressure-sensitive adhesive layer may have a thickness of about 15 to about 100 mu m.

In another embodiment of the present invention, there is provided a touch screen panel comprising a pressure-sensitive adhesive layer formed from the curing composition for a pressure-sensitive adhesive.

The touch screen panel may have a structure in which a conductive plastic film having a conductive layer formed on one side thereof, the adhesive layer, and a cover window are sequentially stacked.

The conductive film may be a transparent plastic film having an ITO electrode layer on one side thereof.

The curable composition for a pressure-sensitive adhesive can be applied to a pressure-sensitive adhesive having excellent durability.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

In one embodiment of the present invention, there is provided a cured composition for a pressure-sensitive adhesive which is cured to have a gel content of about 80 wt% or more from a hydroxy group-containing acrylic resin and a peroxide curing agent.

The curing composition for a pressure-sensitive adhesive is formed as a cured product by radical curing between hydrogen atoms in the main chain of the acrylic resin, not by curing the hydroxy groups of the acrylic resin containing the hydroxy group, using a peroxide-based curing agent.

The curing composition for a pressure-sensitive adhesive contains a cured product of the hydroxy-containing acrylic resin and the peroxide-based curing agent. The hydroxy group-containing acrylic resin is a thermosetting resin, and a crosslinked part is cured by the curing reaction with the curing agent, and the content of the gelated part can be measured by the gel content.

As described above, the curing composition for a pressure-sensitive adhesive has a high gel content of about 80 wt% or more due to radical curing, and can have an excellent peeling force and can realize a high-durability pressure-sensitive adhesive.

The curing composition for a pressure sensitive adhesive has excellent workability by using a peroxide-based curing agent and does not require a separate aging period after the pressure-sensitive adhesive processing, thereby achieving a thermosetting pressure-sensitive adhesive capable of achieving the adhesive performance in a short time. This is because crosslinking by the peroxide-based curing agent is completed in the curing step after the drying, and therefore no aging time is required. Therefore, it is possible to provide a pressure-sensitive adhesive excellent in productivity by reaching a practical performance in a short time.

Further, the curable composition for a pressure-sensitive adhesive can maintain excellent durability for a long period of time without lifting, peeling or bubbling even under high temperature and high humidity conditions, and can realize a pressure-sensitive adhesive excellent in wettability, adhesiveness and workability to various adherends have.

The hydroxy group-containing acrylic resin may be a copolymer of a hydroxy group-containing monomer and a meta (acrylic) alkyl ester monomer.

Specifically, the hydroxy group-containing acrylic resin may be copolymerized with about 0.1 to about 30% by weight, specifically about 0.1 to about 25% by weight, of the hydroxyl group-containing monomer in 100% by weight of the sum of the monomers copolymerized. The curable composition for a pressure sensitive adhesive comprising the hydroxyl group-containing acrylic resin copolymerized in the content ratio described above can prevent the whitening phenomenon, inhibit the formation of bubbles during coating, and allow the curable composition for a pressure sensitive adhesive to have a gel content within the range Also, it is possible to provide a pressure-sensitive adhesive which has excellent reliability, handling property, durability and re-peeling property, and which can effectively prevent peeling or peeling due to initial adhesive strength reduction .

Specific examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (Meth) acrylate, 2-hydroxyethyleneglycol (meth) acrylate or 2-hydroxypropyleneglycol (meth) acrylate, and combinations thereof.

Specific examples of the above-mentioned meta (acrylic) alkyl ester monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, Butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate, N-acryloylmorpholine (ACMO), 2-hydroxypropyl (meth) acrylate, isooctyl Butyl acrylate, and combinations thereof.

The method of polymerizing the monomer mixture containing the hydroxy group-containing monomer and the meta (acrylic) alkyl ester monomer to produce the hydroxy group-containing acrylic resin is not particularly limited and may be prepared by a known method. For example, general polymerization methods such as solution polymerization, photopolymerization, bulk polymerization, suspension polymerization, emulsion polymerization and the like can be used.

The curable composition for a pressure-sensitive adhesive is prepared by adding to a composition containing a hydroxy group-containing acrylic resin and a peroxide-series curing agent hexane diol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, propylene glycol diacrylate Diacrylate crosslinking agents including dipropylene glycol diacrylate and tripropylene diacrylate, and trifunctional crosslinking agents such as triacrylate type can be further cured, and curing can be carried out according to the amount of the polyfunctional crosslinking agent The physical properties such as water cohesion and adhesive properties can be controlled.

As the peroxide-based curing agent, known compounds may be used without limitation.

The peroxide-based curing agent can be suitably used if it generates radical active species by heating or light irradiation to promote crosslinking of the base polymer of the cured composition for pressure-sensitive adhesive. However, in consideration of workability and stability, specifically, A peroxide-based curing agent having a half-life temperature of about 70 ° C to about 160 ° C may be used. More specifically, a peroxide-based curing agent may be used at about 100 ° C to about 150 ° C. If the half-life temperature for one minute is too low, the reaction proceeds during storage before the curing composition is coated and dried to increase the viscosity and make the coating impossible. When the half-life temperature for one minute is excessively high, , Side reactions may occur and a large amount of unreacted peroxide may remain, which may lead to crosslinking as time elapses, which may be undesirable.

Specifically, the peroxide-based curing agent may be at least one selected from the group consisting of hydrogen peroxide, ketone peroxide such as acetyl acetone peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide and methyl isobutyl ketone peroxide; Diacyl peroxides such as benzoyl peroxide, lauroyl peroxide, isobutyryl peroxide, acetyl peroxide, 2,4-dichlorobenzoyl peroxide, succinic acid peroxide, decanoyl peroxide, diisononanoyl peroxide; Perester such as tert-butyl peroxide-2-ethylhexanoate; Perketal such as 1,1-ditert-butylperoxy-3,3,5-trimethylcyclohexane and dialkyl peroxides such as 1,3-bis (tert-butylperoxyisopropyl) have.

The curing composition for a pressure-sensitive adhesive may include a cured product obtained by mixing and curing the composition at a ratio of about 0.05 to about 5 parts by weight of the peroxide-based curing agent relative to 100 parts by weight of the hydroxy group-containing acrylic resin. By using the peroxide curing agent having the above-mentioned range, the curing reaction can be efficiently performed, and the yellowing caused by the peroxide can be prevented from occurring, making it suitable for use as an optical sub-material.

As described above, the curable composition for a pressure sensitive adhesive exhibits a high gel content and thus has excellent durability and excellent peel strength. Specifically, the curing composition for a pressure sensitive adhesive may have a peel strength of about 1600 gf / in or more, more specifically about 1700 to about 3000 gf / in, measured at a peel rate of about 300 mm / min and a peel angle of about 180 °.

The curing composition for a pressure-sensitive adhesive may be, for example, thermally cured after addition of a curing accelerator in addition to the composition comprising a hydroxy group-containing acrylic resin, the peroxide-based curing agent and optionally a polyfunctional crosslinking agent. The curing accelerator may be, for example, a tertiary amine and specifically includes N, N-dimethylaniline (DMA), N, N-diethylaniline (DEA) (2-hydroxyethyl) -p-toluidine (HEPT), N, N-dimethyl-p-toluidine (DMPT) Hydroxyethyl) -p-toluidine (MHPT).

In another embodiment of the present invention, there is provided an optical adhesive film comprising a pressure-sensitive adhesive layer formed from the curing composition for a pressure-sensitive adhesive. The curing composition for a pressure-sensitive adhesive may evaporate the solvent in the curing process, form a coating film, and form the pressure-sensitive adhesive layer.

The optical adhesive film may be applied to a touch screen panel of a display device such as a mobile, tablet PC, or the like. For example, the optical adhesive film can be used to form an interlaminar adhesive layer in laminating a laminate of the touch screen panel.

Since the pressure-sensitive adhesive layer is formed of an optically clear adhesive layer (OCA), the pressure-sensitive adhesive layer can be formed as a whole stacked in the laminate of the touch screen panel.

The pressure-sensitive adhesive layer may be formed to have a thickness of, for example, about 15 탆 to about 100 탆.

The pressure-sensitive adhesive layer has excellent durability and high peeling force to which the curable composition for pressure-sensitive adhesive is applied.

In another embodiment of the present invention, there is provided a touch screen panel comprising a pressure-sensitive adhesive layer formed from the curing composition for a pressure-sensitive adhesive.

The touch screen panel may have a structure in which a conductive plastic film having a conductive layer formed on one side thereof, the adhesive layer, and a cover window are sequentially stacked.

The conductive film may be a transparent plastic film having an ITO electrode layer on one side thereof.

The pressure-sensitive adhesive layer has a high gel content and may not cause corrosion of the ITO electrode layer.

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

( Example )

Manufacturing example  1: Synthesis of hydroxy group-containing acrylic resin

53 parts by weight of ethylhexyl acrylate (EHA), 24 parts by weight of isobornyl acrylate (IBOA), and 5 parts by weight of N-acryloylmorpholine (ACMO) were added to a 2 L reactor equipped with a cooling device for nitrogen gas flow- And 18 parts by weight of 2-hydroxybutyl acrylate (HBA) were charged, and ethyl acetate (EAc) was added as a solvent to give a 1,200,000 weight average molecular weight and a glass transition temperature of -28 DEG C To prepare an acrylic resin (A).

Example  One

1.5 parts by weight of benzoyl peroxide and 0.2 parts by weight of a silane coupling agent (KBM 403, ShinEtsu) were added to 100 parts by weight of the hydroxy group-containing acrylic resin prepared in Preparation Example 1 to prepare a mixed composition, And diluted to prepare a coating solution. Subsequently, the prepared coating solution was coated on a release-treated polyethylene terephthalate (PET) film (thickness: 75 μm) and coated thereon to a thickness of about 50 μm. Thereafter, it was dried at a temperature of about 150 캜 for about 3 minutes or longer to form a pressure-sensitive adhesive layer having a thickness of 50 탆 (as a reference after drying). Then, the pressure-sensitive adhesive layer was adhered to both sides of a PET release film having a thickness of 12 占 퐉 to prepare an optical adhesive film.

Example  2

An optical adhesive film was prepared in the same manner as in Example 1, except that lauroyl peroxide as a curing agent was used and dried at 140 ° C for 3 minutes to thermoset.

Comparative Example  One

(MHI-80B manufactured by Asahi Kasei) of hexamethylene diisocyanate (HDI) as a curing agent was used. The curing agent content was 0.3 wt.% Based on 100 parts by weight of the hydroxyacryl resin prepared in Preparation Example 1 And 0.2 parts by weight of a silane coupling agent (KBM 403, ShinEtsu) were mixed to prepare a mixed composition, which was diluted with a solvent to prepare a coating solution. An optical adhesive film was prepared in the same manner as in Example 1, except that the film was dried at 110 ° C for 3 minutes, thermally cured, and aged at 50 ° C for 3 days.

evaluation

Experimental Example  1: Measurement of gel content

The optical adhesive films prepared in Example 1-2 and Comparative Example 1 were stored in a constant temperature and humidity chamber (23 ° C, 60% RH) for about 7 days. Subsequently, 0.3 g of the cured composition was collected from the pressure-sensitive adhesive layer of each optical adhesive film, placed in a stainless steel 200 mesh wire net, immersed in 100 mL of ethyl acetate, and stored in a dark room at room temperature for 48 hours. Subsequently, after the insoluble fractions were separated, the above was dried in an oven at 120 ° C for 4 hours, and the dry mass thereof was measured. Thereafter, the measurement results of the respective masses were substituted into the above-mentioned formula 1 to determine the gel content.

<Formula 1>

Gel content (%) = B / A x 100

In the formula (1), A represents the mass of the cured composition collected from the optical adhesive film, and B represents the mass of the cured composition obtained by immersing the cured composition in ethyl acetate at room temperature for 48 hours, It represents the dry weight of the insoluble fraction measured after removal of ethyl acetate.

Experimental Example  2: Peel force  evaluation

The optical adhesive films prepared in Examples 1-2 and Comparative Example 1 were cut to a size of 25 mm x 20 cm (width x length) to prepare specimens. Thereafter, one surface of the specimen was reciprocated five times with a 2 kg roller on a glass substrate surface, and after 30 minutes passed, the specimen was subjected to a tensile tester at a peel rate of 300 mm / min and a peel angle of 180 The peeling force was measured.

Experimental Example  3: Durability evaluation

The release films were removed from the optical adhesive films prepared in Examples 1-2 and Comparative Examples 1 and 2, and a hard coated surface of a hard coated polycarbonate (PC) film was attached to one side of the pressure sensitive adhesive layer. (ITO side of PET film / pressure-sensitive adhesive / hard film side of PC film) of ITO side of a polyethylene terephthalate (PET) film having an ITO layer formed on one side thereof. Thereafter, the specimens were allowed to stand for 1 day under constant temperature and humidity conditions of 85 ° C and 85% RH, and then stored for 1 day, and then visually observed for extensibility was evaluated according to the following criteria.

<Evaluation Criteria>

○: No lifting observed

X: Excrement observed

division Gel content (%) Peel force (gf / in) durability Example 1 85 2300 ○ Example 2 87 2000 ○ Comparative Example 1 86 1500 ×

In the case of Examples 1 and 2, durability was excellent under high temperature and high humidity conditions such as no bubble, peeling or peeling. On the other hand, Comparative Example 1 had a similar gel content, but the hydroxy groups already participated in the curing reaction, resulting in a poor releasability and durability due to the lack of a hydroxyl group capable of realizing adhesion.

Claims (15)

A curing composition for a pressure-sensitive adhesive which is cured to have a gel content of 80 wt% or more from a hydroxy group-containing acrylic resin and a peroxide curing agent. The method according to claim 1,
The hydroxy group-containing acrylic resin may be prepared by copolymerizing 0.1 to 30% by weight of a hydroxyl group-containing monomer in 100% by weight of the sum of monomers copolymerized
Curable composition for a pressure-sensitive adhesive. The method according to claim 1,
(Meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (Meth) acrylate, 2-hydroxyethyleneglycol (meth) acrylate or 2-hydroxypropyleneglycol (meth) acrylate, and combinations thereof.
Curable composition for a pressure-sensitive adhesive. The method according to claim 1,
The peroxide-based curing agent has a one-minute half-life temperature of 70 to 160 ° C
Curable composition for a pressure-sensitive adhesive. The method according to claim 1,
Wherein the peroxide curing agent comprises one selected from the group consisting of hydrogen peroxide, ketone peroxide, diacyl peroxide, perester, dialkyl peroxide, and combinations thereof
Curable composition for a pressure-sensitive adhesive. The method according to claim 1,
The hydroxy group-containing acrylic resin is obtained by copolymerizing a hydroxy group-containing monomer and a meta (acrylic) alkyl ester monomer
Curable composition for a pressure-sensitive adhesive. The method according to claim 6,
The (meth) acrylic alkyl ester monomer may be selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, Butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl Acrylate, N-acryloylmorpholine (ACMO), 2-hydroxybutyl acrylate (N-acryloxypropyl acrylate) &Lt; / RTI &gt; and combinations thereof.
Curable composition for a pressure-sensitive adhesive. The method according to claim 1,
And a cured product which is cured at a content ratio of 0.05 to 5 parts by weight of the peroxide-based curing agent relative to 100 parts by weight of the hydroxy group-containing acrylic resin
Curable composition for a pressure-sensitive adhesive. The method according to claim 1,
The curing composition for a pressure-sensitive adhesive may be obtained by curing a mixture obtained by further adding a polyfunctional crosslinking agent, a curing accelerator or both of the above-mentioned hydroxy group-containing acrylic resin and the peroxide-
Curable composition for a pressure-sensitive adhesive. The method according to claim 1,
A peel strength of 1600 to 3000 g / in
Curable composition for a pressure-sensitive adhesive. An optical adhesive film comprising a pressure-sensitive adhesive layer formed from the curable composition for a pressure-sensitive adhesive according to any one of claims 1 to 10. 11. The method of claim 10,
The pressure-sensitive adhesive layer has a thickness of 15 to 100 mu m
Optical adhesive film. A touch screen panel comprising a pressure-sensitive adhesive layer formed from the curable composition for a pressure-sensitive adhesive according to any one of claims 1 to 10. 14. The method of claim 13,
A conductive plastic film having a conductive layer formed on one surface thereof, a pressure-sensitive adhesive layer and a cover window,
Touch screen panel. 15. The method of claim 14,
The conductive film is a transparent plastic film having an ITO electrode layer formed on one surface thereof
Touch screen panel.