JP2022536080A - Radical adhesive composition, protective film for polarizing plate containing the same, polarizing plate containing the same, and image display device containing the same - Google Patents

Abstract

TECHNICAL FIELD The present invention relates to a radical adhesive composition, a polarizing plate protective film containing the same, a polarizing plate containing the same, and an image display device containing the same. [Selection drawing] Fig. 1

Description

The present invention claims the benefit of the filing date of Korean Patent Application No. 10-2019-0073558 filed with the Korean Intellectual Property Office on June 20, 2019, the entire contents of which are incorporated into the present invention. .

TECHNICAL FIELD The present invention relates to a radical adhesive composition, a polarizing plate protective film containing the same, a polarizing plate containing the same, and an image display device containing the same.

Generally, a polarizing plate has a structure in which a protective film is laminated on one or both sides of a polarizer made of a polyvinyl alcohol (hereinafter referred to as PVA) resin dyed with a dichroic dye or iodine using an adhesive. Conventionally, a triacetyl cellulose (hereinafter referred to as TAC) film has been mainly used as a polarizing plate protective film, but the TAC film has a problem that it is easily deformed in a high temperature and high humidity environment. Therefore, in recent years, protective films made of various materials to replace TAC films have been developed. Alternatively, a method of using them in combination has been proposed.

Here, as the adhesive for adhering the polarizer and the protective film, a water-based adhesive mainly composed of an aqueous solution of a polyvinyl alcohol-based resin is used. However, in the water-based adhesive, if an acrylic film or a COP film, which is not TAC, is used as a protective film, the adhesive strength is weak, so there is a problem that its use is limited depending on the material of the film. In addition, in the water-based adhesive, in addition to the problem of poor adhesion depending on the material, if the materials of the protective films applied to both sides of the PVA element are different, the polarizing plate may curl during the drying process of the water-based adhesive. Problems such as generation problems and deterioration of initial optical properties arise. Furthermore, when the water-based adhesive is used, a drying process is always required, and the drying process causes a difference in moisture permeability, thermal expansion, etc., resulting in a problem of a high defect rate. As an alternative to solve the above problem, a method of using a non-aqueous adhesive instead of a water-based adhesive has been proposed.

Therefore, a method has been proposed to improve the reliability and yield of polarizing plates by using a cationic polymerizable UV-curable adhesive instead of a water-based adhesive.

The cationic polymerizable UV-curable adhesive has epoxy as a main component, and has the advantages of high curing density and high reliability. However, in such cationic polymerization, the ring-opening reaction of the epoxy ring progresses due to the dark reaction (post-polymerization) after UV irradiation, which is susceptible to the effects of humidity during curing, causing deviations in the cured state. There is the problem of ease. Therefore, in order to develop a uniform cured state, it is necessary to strictly control not only the environmental humidity but also the water content of the PVA-based polarizer.

Radically polymerizable UV-curable adhesives are excellent in that they have relatively little problem of non-uniform adhesive force due to moisture. Since the curing reaction is not inhibited by moisture, the reaction is not inhibited by the moisture in the polarizer and reacts stably with light energy.

In addition, from the viewpoint of thickness reduction and durability of the polarizing plate, the thinner the thickness of the adhesive layer is, the more advantageous it is.

However, in radical compounds, monofunctional ones are mainly used to maintain low viscosity, which leads to low cured density and adhesive strength, and good margins in post-processing and reliability cannot be expected.

Considering the reliability of the polarizing plate at high temperature and high humidity, the higher the rigidity of the adhesive layer after curing, the lower the rate of dimensional change at high temperature and high humidity, which is advantageous for reducing the defect rate of the polarizer.

In order to satisfy such adhesive properties, it is possible to apply a polyfunctional monomer or a homopolymer with a high glass transition temperature. .

Therefore, we conducted a series of experiments to achieve low viscosity characteristics of the adhesive and high rigidity after curing, and found that by appropriately adjusting the cured density of the radical compound, a highly reliable adhesive composition was obtained. .

Japanese Patent Application Laid-Open No. 2015-011094 (Published date: January 19, 2015)

TECHNICAL FIELD The present invention relates to a radical adhesive composition, a polarizing plate protective film containing the same, a polarizing plate containing the same, and an image display device containing the same.

The present invention provides a polyester-based urethane acrylate oligomer (A) having an acid value of 90 mgKOH/g to 180 mgKOH/g and a polyfunctional (meth)acrylate monomer having a homopolymer glass transition temperature (Tg) of 150° C. or higher. Provided is a radical adhesive composition comprising (B), a (meth)acrylate monomer having a hydrophilic functional group (C), and a silane coupling agent (D).

The present invention also provides a polarizing plate protective film comprising a protective film and an adhesive layer containing the radical adhesive composition on one or both sides of the protective film.

Furthermore, the present invention provides a polarizing plate comprising a polarizer and the polarizing plate protective film on one or both sides of the polarizer.

Furthermore, the present invention provides an image display device comprising a display panel and the polarizing plates on one side or both sides of the display panel.

The present invention provides a radical adhesive composition that has the advantage of providing excellent adhesion to substrates without additional treatment such as corona treatment. In addition, since the radical adhesive composition according to one embodiment of the present invention has a high glass transition temperature and a high storage modulus at high temperatures after curing, excellent heat resistance can be achieved.

It is a figure which shows an example of the lamination structure of the polarizing plate by one Embodiment of this invention. FIG. 4 is a diagram showing another example of a laminated structure of polarizing plates according to an embodiment of the present invention; 4 is a diagram showing an experimental method of Experimental Example 1. FIG. FIG. 10 is a diagram showing an experimental method of Experimental Example 5;

The present invention will be described in detail below.

In the present invention, when a part "includes" a component, it means that it may further include other components, rather than excluding other components, unless otherwise specified.

In the present invention, when a member is said to be "on" another member, it includes not only a member that is in contact with another member, but also a member that has another member between them. included.

The "radical adhesive composition" in the present invention does not contain other polymerizable compounds other than radically polymerizable compounds, or contains a small amount, for example, less than 10 parts by weight or 1 part by weight with respect to 100 parts by weight of the entire composition. means an adhesive composition containing less than In the present invention, the urethane acrylate oligomer, the polyfunctional (meth)acrylate monomer, and the (meth)acrylate monomer having a hydrophilic functional group are all radically polymerizable compounds.

One embodiment of the present invention is a polyester-based urethane acrylate oligomer (A) having an acid value of 90 mgKOH/g to 180 mgKOH/g, and a polyfunctional homopolymer having a glass transition temperature (Tg) of 150° C. or higher ( A radical adhesive composition comprising a meth)acrylate monomer (B), a (meth)acrylate monomer having a hydrophilic functional group (C), and a silane coupling agent (D) is provided.

The radical-based adhesive composition contains a polyester-based urethane acrylate oligomer (A), and even if the glass transition temperature (Tg) of the composition as a whole is lowered, the polyester group provides relaxation, resulting in excellent heat resistance and water resistance. It has the advantage of being flexible. In addition, the radical-based adhesive composition has the advantage of providing excellent adhesion to protective films without the need for additional treatment such as corona treatment. In particular, the polyester-based urethane acrylate oligomer (A) has the effect of providing superior adhesion to a protective film that has not been pretreated, compared to other oligomers such as epoxy-based urethane acrylate oligomers. When the radical adhesive composition is applied to the protective film, the ester group having an acid value erodes the bonding surface of the protective film with the adhesive, and the adhesive composition easily permeates into the surface of the protective film. structure. In other words, the physical effect and the chemical effect of the ester group are realized at the same time, so that the adhesion to the protective film can be increased.

By adjusting the acid value of the polyester-based urethane acrylate oligomer, the adhesion of the adhesive composition to the protective film can be improved. Specifically, the acid value of the polyester urethane acrylate oligomer is 90 mgKOH/g to 180 mgKOH/g, preferably 95 mgKOH/g to 175 mgKOH/g, more preferably 100 mgKOH/g to 170 mgKOH/g. Within the above range, the adhesive composition effectively etches the protective film, ensuring excellent adhesion to the protective film. If the acid value does not reach the above range, the degree of etching of the protective film is small, resulting in a decrease in adhesive strength. If the above range is exceeded, there is a problem of excessive etching of the protective film. Adjust to range.

The acid value is a measurement of the equivalent amount of KOH required to neutralize the acid component of the polyvalent acid or its ester contained in the sample (the carboxy group of the polyvalent acid). It means an amount equivalent to milliequivalents of the same amount of KOH as the component. The said acid value is calculated|required by the following method.

First, in order to measure the acid value of the synthesized acrylate oligomer, a 0.1N potassium hydroxide solution used for titration is prepared. 5.9 g of 95 wt % reagent grade potassium hydroxide is placed in a 1 L volumetric flask, and then a small amount of water is added to dissolve completely. Methanol is added to this and mixed so that the total volume becomes 1 L to prepare a titration solution.

In order to obtain the correction factor of the prepared titrant solution, 10 mL of 35 wt % HCl solution is placed in a beaker, and 2-3 drops of phenolphthalein indicator are added. To this is added the 0.1 N potassium hydroxide titration solution prepared as described above until it turns pale red, and then the volume used is determined. Of the values obtained by repeating this experiment three times, the remaining three values excluding the maximum and minimum values are averaged to obtain the average value A (mL), and then the correction coefficient f is obtained by the following formula.

f=5.611/A

About 1 g of a sample is taken, the mass (M) is accurately measured, and then dissolved in 42.8 g (50 mL) of toluene. Add 2 to 3 drops of 1 wt% phenolphthalein indicator and titrate with 0.1N potassium hydroxide solution while stirring. to calculate

Acid value (Acid Value) = 5.611 x N x f x B/M

where N is the concentration of the potassium hydroxide standard solution, f is the correction factor of the potassium hydroxide solution, B is the consumption (mL) of the potassium hydroxide solution, and M is the sample Mass (g).

The method for determining the acid value described above is an example of an acid-base titration method in which the carboxy group of a polyvalent acid or its ester is titrated with KOH, which is a base, and a known method for analyzing an unreacted acid component or its ester component is used. may be used. For example, for the ester component of a polyvalent acid, the unreacted ester component in 1 kg of a sample is analyzed using gas chromatography analysis or the like, and then the corresponding amount of KOH is calculated to obtain the acid value. good.

The polyester-based urethane acrylate oligomer forms a crosslinked structure with a polyfunctional (meth)acrylate-based reactive monomer, which is a photoreactive monomer, and improves the physical properties (e.g., hardness, adhesion, flexibility, etc.) of the cured resin. It is a controlling component, and when applied to a radical adhesive composition, it can further improve moldability, elasticity and adhesiveness.

The urethane acrylate oligomer is a chemical structure having acrylate groups at both ends of the oligomer structure. Specifically, the urethane acrylate oligomer may be formed of a composition containing a polyester-based polyol compound, an isocyanate-based compound, and an acrylate-based compound.

The polyester-based urethane acrylate oligomer may be synthesized in the following synthesis process. That is, a polyester-based polyol compound (P) having an ester group (R ₁ ) is reacted with a diisocyanate-based compound (I) to primarily synthesize a terminal having an isocyanate group, and then an acrylate-based compound having a hydroxy group ( A) may be reacted with isocyanate groups to produce the final polyester-based urethane acrylate oligomer. Further, it may be a polymer (co-polymer) synthesized according to the following reaction formula, or may be in the form of a mixture (mixture) in which raw materials are simply mixed.

The polyester-based polyol compound causes the oligomer to include a polyester chemical structure in the main chain, and as a result, if the oligomer has the same degree of curing, the step absorbability is higher than that of an oligomer that does not contain a polyester chemical structure. Often, the efficiency of the curing reaction is high, which is advantageous for ensuring reliability.

Specifically, the diisocyanate-based compound is selected from the group consisting of 1,6-hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), xylene diisocyanate (XDI) and combinations thereof. may include one. Specifically, the diisocyanate-based compound may include isophorone diisocyanate (IPDI), in which case the oligomer will include a cycloalkylene structure chemical structure in its main chain, resulting in such a chemical structure Compared to the case without

The acrylate-based compound is a compound for imparting acrylate groups to both ends of the oligomer, and may include an acrylate compound having a hydroxy group. Specifically, the acrylate-based compound may include one selected from the group consisting of hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), hydroxybutyl acrylate (HBA), and combinations thereof.

In one embodiment of the present invention, the polyester-based urethane acrylate oligomer has a number average molecular weight of 1,000 to 50,000, preferably 1,000 to 35,000, more preferably 1,000 to 20,000. . If the number average molecular weight of the urethane acrylate oligomer is less than 1,000, the cured adhesive layer will have reduced wear resistance, adhesion and chemical resistance. Further, when the number average molecular weight of the urethane acrylate oligomer exceeds 50,000, the pencil hardness, abrasion resistance, adhesion and chemical resistance of the cured adhesive layer are lowered.

In one embodiment of the present invention, the number of functional groups of the polyester-based urethane acrylate oligomer may be 1-10. Considering photocuring speed and water resistance, the polyester urethane acrylate oligomer should have 1 to 8 functional groups, preferably 2 to 6 functional groups. Here, the urethane acrylate oligomer having a specific number of functional groups is a concept including other urethane acrylate oligomers that substantially function as urethane acrylate oligomers having the specific number of functional groups. For example, in a urethane acrylate oligomer having 10 functional groups, if one functional group among the functional groups does not show activity substantially, the urethane acrylate oligomer having 10 functional groups has 9 functional groups. included in urethane acrylate oligomers having groups.

In one embodiment of the present invention, the polyester-based urethane acrylate oligomer has a viscosity at 25° C. of 1,000 cPs or more and 50,000 cPs or less, preferably 2,000 cPs or more and 50,000 cPs or less, more preferably 2,500 cPs or more. , 50,000 cPs or less. When a cured product is produced within the viscosity and molecular weight ranges described above, it is excellent in moldability, elasticity, adhesiveness, and the like.

In one embodiment of the present invention, the radical adhesive composition contains 1 to 20 parts by weight, preferably 1 to 15 parts by weight, more preferably 1 to 15 parts by weight of the polyester-based urethane acrylate oligomer with respect to 100 parts by weight of the entire composition. Contains 1 to 10 parts by weight. If the content of the urethane acrylate oligomer is less than 1 part by weight, the adhesion and durability of the cured adhesive layer are lowered. When the content of the urethane acrylate oligomer exceeds 20 parts by weight, the cured adhesive layer becomes excessively flexible, resulting in a decrease in pencil hardness and abrasion resistance as well as an increase in viscosity of the radical adhesive composition. and workability is reduced.

In one embodiment of the present invention, the radical adhesive composition further comprises a polyfunctional (meth)acrylate monomer (B2) whose homopolymer glass transition temperature (Tg) is less than 150°C.

In one embodiment of the present invention, the radical adhesive composition may contain two or more polyfunctional (meth)acrylate monomers. When two or more polyfunctional (meth)acrylate monomers are contained, the curing density is more suitable than that of a radically polymerizable compound containing one polyfunctional (meth)acrylate monomer, and good adhesive strength is imparted. can be done. Therefore, when the adhesive composition is applied to the polarizing plate, cracking of the polarizer due to thermal shock can be prevented.

In one embodiment of the present invention, the radical adhesive composition may contain two polyfunctional acrylate compounds. For example, a polyfunctional acrylate compound having a glass transition temperature of 100° C. or higher and less than 150° C. may be combined with a polyfunctional acrylate compound having a glass transition temperature of 150° C. or higher. You may combine the polyfunctional acrylate compound of the structure containing.

In one embodiment of the present invention, the total content of said polyfunctional (meth)acrylate monomers (if more polyfunctional (meth)acrylate monomers which are less than 150°C are included, the polyfunctionality which is less than 150°C (Total content including the content of the (meth)acrylate monomer) is about 55 to 70 parts by weight, or about 55 to 65 parts by weight with respect to 100 parts by weight of the radical adhesive composition. is preferred. When the total content of the polyfunctional acrylate compound is within the above range, it is possible to ensure a high storage modulus after curing while maintaining good adhesiveness.

In one embodiment of the present invention, the radical adhesive composition may further contain a monofunctional acrylate compound. The amount of the monofunctional acrylate compound is preferably about 0.01 to 25 parts by weight, or about 1 to 25 parts by weight with respect to 100 parts by weight of the radical adhesive composition. Examples of the monofunctional acrylate compound include phenoxyethyl acrylate, benzyl acrylate, isobornyl acrylate, tetrahydrofuranyl acrylate, isodecyl acrylate, and lauryl acrylate, but are not limited thereto.

In one embodiment of the present invention, the radical adhesive composition contains a (meth)acrylate monomer (C) having a hydrophilic functional group. The (meth)acrylate monomer (C) may have one or more hydrophilic functional groups in the molecule. The (meth)acrylate monomer (C) having a hydrophilic functional group has the effect of improving the compatibility with the substrate and increasing the compatibility between the substrate surface and the adhesive. In particular, when used in a polarizer, the adhesive composition between the substrate and the polarizer can have excellent adhesive strength.

Further, as the (meth)acrylate monomer (C) having a hydrophilic functional group, any monomer can be used as long as radical polymerization is possible due to the presence of a carbon-carbon unsaturated double bond in the molecule. good too. Here, the hydrophilic functional group is not particularly limited as long as it can form a hydrogen bond, such as a hydroxy group, a carboxyl group, a urethane group, an amino group, and an amide group. It is preferable for realization of adhesive force. For example, the (meth)acrylate monomer having a hydrophilic functional group is a (meth)acrylate having an alkyl group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, having at least one hydroxy group. For example, monofunctional (meth)acrylates having a hydroxy group include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, One or more of 6-hydroxyhexyl (meth)acrylate and 2-hydroxy-3-phenoxypropyl (meth)acrylate may be used, and these may be used alone or in combination of two or more. good.

The content of the (meth)acrylate monomer (C) having a hydrophilic functional group is 10 to 20 parts by weight, or 15 to 20 parts by weight with respect to 100 parts by weight of the radical adhesive composition. Preferably.

In one embodiment of the present invention, the radical adhesive composition may contain two or more polyfunctional (meth)acrylate monomers and one (meth)acrylate monomer having a hydrophilic functional group.

In one embodiment of the present invention, the radical adhesive composition contains a polyfunctional (meth)acrylate monomer (B) whose homopolymer has a glass transition temperature (Tg) of 150° C. or higher. When a polyfunctional (meth)acrylate monomer having a glass transition temperature of 180° C. or higher is included, it is preferred that the glass transition temperature increases from the Tan δ (Tan Delta) peak and the storage modulus at high temperatures increases. The glass transition temperature of the homopolymer of the polyfunctional (meth)acrylate monomer may be, for example, 400° C. or lower or 300° C. or lower.

Tan δ (Tan Delta) in the present invention means the ratio of storage modulus to loss modulus. Specifically, the Tan δ (Tan Delta) can be expressed by the following formula.

Tan δ (Tan Delta) = storage modulus/loss modulus

The "glass transition temperature" in the present invention means the temperature at which a polymer substance is converted from a hard solid state such as glass to an elastic rubber state. Since the glass transition temperature is determined by the structural properties of the monomers, polymers have unique glass transition temperatures depending on the type of monomers polymerized. The lower the glass transition temperature, the more flexible the material, and the higher the glass transition temperature, the harder the material. Since the glass transition temperature of the monomer itself cannot be measured, the glass transition temperature is generally measured by polymerizing a homopolymer of the monomer. However, in the present invention, the glass transition temperature is determined from the Tan delta (Tan Delta) value. The glass transition temperature is defined as the temperature corresponding to Tanδmax having the maximum value (peak) in the Tanδ (Tan Delta) value depending on the temperature.

The polyfunctional (meth)acrylate monomer cures when exposed to radiation to form a second crosslinked structure, making the adhesive harder during curing, so that the low molecular weight acrylic copolymer is used. It is possible to improve the problem of deterioration in durability that occurs when using, and to secure a desired storage elastic modulus (G'). It is also a component that facilitates coating by diluting the adhesive composition to adjust the viscosity. That is, the polyfunctional (meth)acrylate monomer serves to improve the workability of the adhesive composition by imparting durability to the cured adhesive layer, maintaining viscoelasticity, and controlling viscosity.

Examples of the polyfunctional (meth)acrylate monomer (B) whose homopolymer has a glass transition temperature (Tg) of 150° C. or higher include dimethyloltricyclodecane diacrylate (Tg: 214° C.), (trishydroxyethyl isocyanurate) triacrylate (Tg: 225 ° C.), [2-[1,1-dimethyl-2[(1-oxoallyl)oxy]ethyl]-5-ethyl-1,3-dioxane-5yl]methyl acrylate ( Tg: 180°C), 9,9-bis[4-(2-acryloxyethoxy)phenylfluorene (Tg: 179°C), (trishydroxyethyl isocyanurate) triacrylate (Tg: 275°C), etc. , but not limited to these.

The content of the polyfunctional (meth)acrylate monomer (B) whose homopolymer has a glass transition temperature (Tg) of 150° C. or higher is 5 parts by weight with respect to 100 parts by weight of the radical adhesive composition. It is preferably about 40 parts by weight, 10 parts to 35 parts by weight, or 15 parts to 30 parts by weight. If the content is less than 5 parts by weight, the durability in a high-temperature or high-temperature/high-humidity environment will be reduced, or it will be difficult to suppress light leakage. If the content exceeds 40 parts by weight, the durability will be reduced. .

The glass transition temperature after curing of the radical adhesive composition may be 80° C. or higher and 150° C. or lower. If the glass transition temperature is not reached, the cured product of the radical adhesive composition will have reduced resistance to heat and humidity and durability.

The peak value of Tan δ after curing of the radical adhesive composition may be 0.2 or more, and the glass transition temperature at the peak value of Tan δ may be 90° C. or more. If the above range is not reached, the adhesiveness, moist heat resistance and durability of the cured product of the radical adhesive composition are lowered. If the glass transition temperature corresponding to the Tan δ (Tan Delta) peak is within the above range, the adhesive layer hardly undergoes thermal deformation in the temperature range for evaluating reliability, and high reliability can be ensured.

In order to measure the Tan δ (Tan Delta), first, the radical adhesive composition was coated on a release film, and a light amount of 1,000 mJ/cm ² was irradiated under conditions of a temperature of 23°C and a relative humidity of 55%. A cured film is produced by photocuring. Here, the thickness of the cured film is 30 μm to 50 μm, for example 30 μm. After removing the release film, the sample was prepared in a size of 5.3 mm × 5 mm × 30 μm in width × length × thickness and subjected to a temperature sweep test (strain 0.04%, preload force 0) by DMA Q800 (TA instrument). 05 N, Force Track 125%, Frequency 1 Hz), the temperature is raised from 0° C. to 150° C. at a rate of 5° C./min, and the storage modulus is measured. Then, using an analysis tool, the Y-axis of the resulting graph is set to the numerical change in Tan δ (Tan Delta), and the temperature at Tan δmax with the maximum value is defined as the glass transition temperature.

The storage elastic modulus at 80° C. after curing of the radical adhesive composition is 800 MPa or more and 2,000 MPa or less, preferably 900 MPa or more and 2,000 MPa or less, more preferably 1,000 MPa or more and 2,000 MPa or less. be. The range of storage modulus mentioned above is the storage modulus at 80°C, and the storage modulus at temperatures other than 80°C have different values. If the storage elastic modulus at 80°C is within the above range, the polarizer protective performance of the adhesive layer provided between the polarizer and the protective film is effectively exhibited. Specifically, it is possible to effectively suppress the occurrence of cracks in the polarizer in a severe environment such as thermal shock.

If the storage elastic modulus at 80° C. after curing of the radical adhesive composition is less than 800 MPa, it becomes difficult to suppress shrinkage and expansion of the polarizer due to temperature during the thermal shock evaluation process. occurs and the storage elastic modulus at 80° C. exceeds 2,000 MPa, the polarizing plate bends due to the substrate laminated on the polarizer.

The crack in the present invention means a portion where the polarizing plate is broken long in the MD (machine direction) direction. For example, the length of the crack is 0.01 mm or more.

In order to measure the storage elastic modulus, first, the radical adhesive composition is coated on a release film, and a light amount of 1,000 mJ/cm ² is irradiated at a temperature of 23 ° C. and a relative humidity of 55% to photocure. A cured film is produced by allowing the Here, the thickness of the cured film is 30 μm to 50 μm, for example 30 μm. After removing the release film, the sample prepared in a size of 5.3 mm × 5 mm × 30 μm in width × length × thickness was subjected to a temperature sweep test (strain 0.04%, preload force: DMA Q800 (TA instrument)). 0.05 N, Force Track: 125%, Frequency: 1 Hz), the temperature is raised from 0° C. to 150° C. at a rate of 5° C./min to measure the storage modulus.

The radical adhesive composition may have no ether bond peak (1,080 cm ⁻¹ ) in the IR spectrum after curing. A compound having an epoxy functional group is not a radically polymerizable but a cationic polymerizable material, and even when it is used as an additive for imparting other functions that are not polymerizable, the amount thereof is small. The ether bond peak (1,080 cm ⁻¹ ) disappears in the IR spectrum after curing.

In one embodiment of the present invention, the radical adhesive composition does not contain an epoxy compound as a polymerizable compound and may contain a small amount as an additive. The content of the epoxy compound is 0.1 to 5 parts by weight, preferably 0.1 to 3 parts by weight, more preferably 0.1 part by weight, based on 100 parts by weight of the radical adhesive composition. parts by weight to 1 part by weight.

Whether or not the radical adhesive composition contains an epoxy compound can be confirmed by measuring an IR spectrum. An epoxy-based adhesive composition containing an epoxy compound has an ether bond peak (1,080 cm ⁻¹ ) in an IR spectrum due to an ether bond formed by ring-opening of an epoxy ring, whereas it contains an acrylate compound. The radical adhesive composition has no ether bond peak. Also, in the vicinity of 1,200 cm ⁻¹ to 1,000 cm ⁻¹ , three peaks are observed in the epoxy adhesive composition, but only one peak is observed in the radical adhesive composition.

In one embodiment of the present invention, the radical adhesive composition may contain a light scattering generator (E) or a photoinitiator (F), and the light scattering generator (E) and the photoinitiator (F) may include

As the light-scattering agent (E), any known light-scattering agent can be used. Specific examples thereof include onium salts such as aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, and iron arene complexes. These may be used alone or in combination of two or more.

Examples of the aromatic diazonium salts include benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, and benzenediazonium hexafluoroborate.

Examples of aromatic iodonium salts include diphenyliodonium tetrakis(pentafluorophenyl)borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, and di(4-nonylphenyl)iodonium hexafluorophosphate.

Examples of the aromatic sulfonium salts include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis(pentafluorophenyl)borate, diphenyl[4-(phenylthio)phenyl]sulfonium hexafluoroantimonate, Diphenyl[4-(phenylthio)phenyl]sulfonium hexafluorophosphate, 4,4'-bis[diphenylsulfonio]diphenylsulfide bishexafluorophosphate, 4,4'-bis[di(β-hydroxyethoxy)phenylsulfonio] Diphenylsulfide bishexafluoroantimonate, 4,4′-bis[di(β-hydroxyethoxy)phenylsulfonio]diphenylsulfide bishexafluorophosphate, 7-[di(p-toluoyl)sulfonio]-2-isopropylthioxanthone hexa fluoroantimonate, 7-[di(p-toluoyl)sulfonio]-2-isopropylthioxanthone tetrakis(pentafluorophenyl)borate, 4-phenylcarbonyl-4′-diphenylsulfonio-diphenylsulfide hexafluorophosphate, 4-(p -tert-butylphenylcarbonyl)-4'-diphenylsulfonio-diphenylsulfide hexafluoroantimonate, 4-(p-tert-butylphenylcarbonyl)-4'-di(p-toluoyl)sulfonio-diphenylsulfide tetrakis (penta fluorophenyl)borate, diphenyl[4-(phenylthio)phenyl]sulfonium phosphate, and the like.

Examples of the iron arene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II)-tris ( and trifluoromethylsulfonyl)methanide.

Commercially available light scattering agents may be used, for example, CPI-100P, 101A, 200K, 210S (manufactured by San-Apro Co., Ltd.), kayarad (registered trademark) PCI-220, PCI-620 (manufactured by Japan Kayaku Co., Ltd.), UVI-6990 (manufactured by Union Carbide Co., Ltd.), Adekaoptomer (registered trademark) SP-150, SP-170 (manufactured by ADEKA Co., Ltd.), CI-5102, CIT -1370, 1682, CIP-1866S, 2048S, 2064S (manufactured by Nippon Soda Co., Ltd.), DPI-101, 102, 103, 105, MPI-103, 105, BBI-101, 102, 103, 105, TPS- 101, 102, 103, 105, MDS-103, 105, DTS-102, 103 (manufactured by Midori Chemical Co., Ltd.), PI-2074 (manufactured by Rhodia Japan Co., Ltd.) and the like.

The content of the light scattering generator is preferably 0.5 with respect to 100 parts by weight of the total weight of the radical adhesive composition or the remaining composition of the radical adhesive composition excluding the light scattering generator. It is from 1 part by weight to 7 parts by weight, preferably from 1 part by weight to 4 parts by weight. By setting the amount of the light-scattering agent to 0.5 parts by weight or more, the curing property of the adhesive after ultraviolet irradiation is improved. On the other hand, by setting the amount to 7 parts by weight or less, deterioration of adhesiveness and durability due to bleeding out can be suppressed. The total weight of the radical-based adhesive composition in calculating the content of the light-scattering agent means the sum of the remaining components excluding the light-scattering agent.

The type of the photoinitiator is not particularly limited, and conventionally known photoinitiators can be preferably used. A photoinitiator may be used individually and may be used in combination of 2 or more type.

Specifically, as the photoinitiator, hydrogen peroxide, inorganic peroxides such as potassium persulfate and ammonium persulfate, t-butyl hydroperoxide, di-t-butyl peroxide, cumene hydroperoxide, acetyl peroxide, Organic peroxides such as benzoyl peroxide and lauroyl peroxide, azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate, azobisisobutylamidine hydrochloride, azobiscyanokyl Azo compounds such as herbal acid, acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, 2,3-dialkyldione compounds, disulfide compounds, fluoroamine compounds, aromatic sulfoniums , lophine dimers, onium salts, borates, active esters, active halogens, inorganic complexes, coumarins and the like. More specifically, acetophenone, 3-methylacetophenone, benzyldimethylketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 2-methyl-1-[4-(methylthio ) Acetophenones such as phenyl]-2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzophenone, 4-chlorobenzophenone, 4,4'-diaminobenzophenone, etc. benzophenones, benzoin ethers such as benzoin propyl ether and benzoin ethyl ether, thioxanthones such as 4-isopropylthioxanthone, 1-hydroxycyclohexylphenyl ketone, xanthone, fluorenone, camphorquinone, benzaldehyde, and anthraquinone.

Commercially available photoinitiators may be used, for example IRGACURE® 184, 819, 907, 651, 1700, 1800, 819, 369, 261, DAROCUR® TPO , Darocure (registered trademark) 1173 (manufactured by BASF Japan Co., Ltd.), Esacure (registered trademark) KIP150, TZT (manufactured by DKSH Japan Co., Ltd.), KAYACURE (registered trademark) BMS, DMBI ( (manufactured by Nippon Kayaku Co., Ltd.).

In addition, the photoinitiator includes amines such as ethylamine, triethanolamine and dimethylaniline, polyamines, bivalent iron salt compounds, ammonia, organometallic compounds such as triethylaluminum, triethylboron and diethylzinc, sodium sulfite and sodium hydrogen sulfite. , cobalt naphthenate, sulfinic acid, mercaptan, etc. may be used in combination.

The radical adhesive composition may contain a photosensitizer. The type of the photosensitizer is not particularly limited, and conventionally known photosensitizers can be preferably used. A photosensitizer may be used independently and may be used in combination of 2 or more type.

Specific examples of the photosensitizer include pyrene, benzoin methyl ether, benzoin isopropyl ether, benzoin derivatives such as α-dimethoxy-α-phenylacetophenone, benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, benzophenone derivatives such as 4,4′-bis(dimethylamino)benzophenone and 4,4′-bis(diethylamino)benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone, 2-isopropylthioxanthone and 2,4-diethylthioxanthone; Anthraquinone derivatives such as chloroanthraquinone and 2-methylanthraquinone; acridone derivatives such as N-methylacridone and N-butylacridone; and α-diethoxyacetophenone, benzyl, fluorenone, xanthone, uranyl compounds, and halogen compounds be done.

The photosensitizer may be a synthetic product or a commercially available product. Examples of commercially available products include Kayacure (registered trademark) DMBI, BDMK, BP-100, BMBI, DETX-S, EPA (manufactured by Nippon Kayaku Co., Ltd.), Anthracure (registered trademark) UVS-1331, UVS- 1221 (manufactured by Kawasaki Kasei Co., Ltd.), Uvecryl P102, 103, 104, 105 (manufactured by UCB) and the like.

The amount of at least one of the photoinitiator and the photosensitizer used (when the photoinitiator and the photosensitizer are used in combination, the total amount used) is the photoinitiator and the photosensitizer in the radical adhesive composition. preferably 0.1 parts by weight or more and 7 parts by weight or less, more preferably 0.2 parts by weight or more and 3.5 parts by weight or less; It is 0.2 parts by weight or more and 2.5 parts by weight or less. Within the above range, the efficiency of curing by ultraviolet irradiation is excellent, so deterioration of adhesiveness and durability due to bleeding out can be suppressed.

In one embodiment of the present invention, the type of silane coupling agent (D) is not particularly limited, for example vinylchlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltri Methoxysilane, 3-Methacryloxypropyltriethoxysilane, 3-Methacryloxypropyltrimethoxysilane, 3-Methacryloxypropylmethyldimethoxysilane, 3-Methacryloxypropylmethyldiethoxysilane, 3-Acryloxypropyltrimethoxysilane, N -2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyltriethoxysilane , 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3 -chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane and the like. These may be used alone or in combination of two or more.

The radical-based adhesive composition may, if necessary, contain additives other than the components described above to such an extent that the effects of the present invention are not significantly reduced.

Examples of the additives include other polymerizable components other than the above, ultraviolet absorbers, antioxidants, heat stabilizers, inorganic fillers, softeners, anti-aging agents, stabilizers, tackifier resins, modified resins ( polyol resin, phenolic resin, acrylic resin, polyester resin, polyolefin resin, etc.), leveling agent, defoaming agent, plasticizer, dye, pigment (coloring pigment, extender pigment, etc.), processing agent, UV blocker, fluorescent brightener , dispersants, light stabilizers, antistatic agents, lubricants, and the like.

The content of the additive is preferably 0.01 parts by weight or more and 20 parts by weight or less, and is 0.02 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the entire adhesive composition. more preferably 0.05 parts by weight or more and 5 parts by weight or less. If the content of the additive is within the above range, the effect of the adhesive of the present invention can be sufficiently exhibited. The total weight of the adhesive composition means the sum of the remaining components excluding the additives.

The cured product of the radical adhesive composition has an adhesive strength of 150 gf/20 mm, preferably 170 gf/20 mm, and more preferably 200 gf/20 mm or more to a polyethylene terephthalate film that has not been pretreated. Being within the above range means that the adhesive strength of the radical adhesive composition to a polyethylene terephthalate film is excellent. Within the above numerical range, there is an advantage that pretreatment is not required to improve the adhesive strength of the protective film. The pretreatment is for improving the adhesion of the film, and examples thereof include corona treatment. Whether or not the polyethylene terephthalate film is pretreated can be confirmed by the contact angle. The contact angle of the film is less than 50 degrees. The contact angle can be measured by a method commonly used in the art, for example, by dropping a droplet onto a film and then measuring from the angle formed by the stationary droplet and the film surface. Here, water (DI water) or an organic solvent is used as the type of liquid. Examples of the contact angle tester used for measuring the contact angle include Phonenix 300 and the like.

The viscosity of the radical adhesive composition at 25° C. is 10 cPs or more and 100 cPs or less, preferably 10 cPs or more and 80 cPs or less, more preferably 10 cPs or more and 65 cPs or less. When the viscosity is within this range, the processability of the composition is improved, and the generation of air bubbles in the adhesive layer formed from the adhesive composition can be prevented.

The method for producing the radical adhesive composition is not particularly limited, and is carried out by mixing the above components. An organic solvent may be used as appropriate for viscosity adjustment. The mixing method is not particularly limited, either. In order to prevent the progress of curing, the liquid should be thoroughly stirred at room temperature (20° C. or higher and 25° C. or lower) in a room shielded from UV light until the inside of the liquid becomes uniform. You may make it mix.

The radical-based adhesive composition includes polarizing plates (polarizing films), retardation films, elliptically polarizing films, antireflection films, brightness enhancement films, indium/tin oxide sputtering transparent conductive films (ITO films), and various electronics-related films. Appropriately used for members and protective films. Especially, it is preferably used for a polarizing plate (polarizing film).

The present invention provides a polarizing plate protective film comprising a protective film and an adhesive layer containing the radical adhesive composition on one or both sides of the protective film.

In one embodiment of the present invention, the thickness of the adhesive layer is greater than 0 μm and less than or equal to 20 μm, greater than 0 μm and less than or equal to 10 μm, preferably 0.1 μm to 10 μm, or approximately 0.1 μm to 5 μm. This is because if the thickness of the adhesive layer is too thin, the uniformity and adhesive strength of the adhesive layer will be reduced, and if the thickness of the adhesive layer is too thick, wrinkles will occur in the appearance of the polarizing plate. .

The present invention provides a polarizing plate comprising a polarizer and the polarizing plate protective film on one side or both sides of the polarizer. 1 and 2, the polarizer includes protective films 101 and 105 on one or both sides of a polarizer 103 with adhesive layers 102 and 104 interposed therebetween.

In the present invention, a polarizer known in the art, such as a film made of polyvinyl alcohol (PVA) containing iodine or a dichroic dye, may be used as the polarizer. The polarizer may be produced by dyeing a polyvinyl alcohol film with iodine or a dichroic dye, and the production method is not particularly limited. A polarizer in the present invention means one that does not contain a protective layer (or protective film), and a polarizing plate means one that contains a polarizer and a protective layer (or protective film).

The polarizer includes a process of uniaxially stretching a polyvinyl alcohol resin film, a process of dyeing the polyvinyl alcohol resin film with a dichroic dye, a process of adsorbing the dichroic dye, and a process of adsorbing the dichroic dye. A step of treating the resin film with an aqueous boric acid solution, a step of washing with water after the treatment with the aqueous boric acid solution, and a step of bonding a protective layer to a uniaxially stretched polyvinyl alcohol resin film in which a dichroic dye is adsorbed and oriented by performing these steps. It is made through

The uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing with a dichroic dye, or may be performed after dyeing with a dichroic dye. When uniaxial stretching is performed after dyeing with a dichroic dye, the uniaxial stretching may be performed before or during boric acid treatment. Moreover, you may uniaxially stretch in these several steps. In order to perform uniaxial stretching, the film may be uniaxially stretched between rolls having different circumferential speeds, or may be uniaxially stretched using hot rolls. Alternatively, dry stretching in which stretching is performed in the atmosphere, or wet stretching in which stretching is performed in a state of being swollen with a solvent may be used. The draw ratio is not particularly limited, and is usually 4 to 8 times.

On the other hand, the polarizer preferably has a thickness of 5 μm to 40 μm, more preferably 5 μm to 25 μm. If the thickness of the polarizer is thinner than the numerical range, the optical properties are deteriorated. Resistance to heat is reduced.

When the polarizer is a polyvinyl alcohol film, any polyvinyl alcohol film may be used as long as it contains a polyvinyl alcohol resin or a derivative thereof. Examples of the derivative of the polyvinyl alcohol resin include polyvinyl formal resin and polyvinyl acetal resin, but are not limited to these. Commercially available polyvinyl alcohol films such as P30, PE30, and PE60 from Kuraray Co., Ltd., and M2000, M3000, and M6000 from Nippon Gosei Co., Ltd. may also be used, but are not limited to these.

The polyvinyl alcohol film preferably has a polymerization degree of 1,000 to 10,000, more preferably 1,500 to 5,000. If the degree of polymerization is within the above numerical range, the movement of the molecules becomes free, and it is flexibly mixed with iodine, dichroic dyes, and the like.

As the protective film material, a material excellent in transparency, mechanical strength, thermal stability, moisture blocking property, isotropy, etc. is preferable. For example, cellulose resins such as cellulose diacetate and cellulose triacetate; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; acrylic resins such as polymethyl methacrylate (PMMA); Polyolefin resins such as resins, polycarbonate resins, polyethylene, polypropylene, ethylene/propylene copolymers, and cycloolefin polymers, polyamide resins such as polyvinyl chloride resins, nylon, and aromatic polyamides, polyimide resins, polysulfone resins, polyethersulfone resins, Polyether ether ketone resins, polyphenylene sulfide resins, polyvinyl alcohol resins, polyvinylidene chloride resins, polyvinyl butyral resins, polyarylate resins, polyoxymethylene resins, epoxy resins, blends of these resins, and the like.

The protective film is preferably the cellulose film described above.

Specifically, cellulose resin, which is an ester of cellulose and fatty acid, cycloolefin polymer (COP), polyethylene terephthalate (PET), or acrylic resin is preferred. Examples of the cellulose resin include cellulose triacetate (TAC), cellulose diacetate, cellulose tripropionate and cellulose dipropionate. Among these, cellulose triacetate, cycloolefin polymer, polyethylene terephthalate, or acrylic resin is preferable from the viewpoint of availability and cost, and cycloolefin polymer, polyethylene terephthalate, or acrylic resin is more preferable in consideration of availability and moisture permeability. . If the moisture permeability of the protective film is high, moisture will easily permeate the protective film and enter the polarizer side, possibly degrading the quality of the polarizer. , it can be significantly suppressed.

Moreover, saponified cellulose triacetate may be used, but non-saponified cellulose triacetate is more preferable.

The surface of the protective film may be modified by corona discharge treatment. The corona discharge treatment method is not particularly limited, and treatment can be performed using a general corona discharge treatment apparatus (eg, manufactured by Kasuga Denki Co., Ltd.). It is believed that the corona discharge treatment forms active groups such as hydroxyl groups on the surface of the protective film, which contributes to the improvement of adhesiveness. When saponified cellulose triacetate is used as the protective film, the corona discharge treatment is not necessarily required because the same adhesiveness improvement effect as the corona discharge treatment is expected. However, since the saponification process is complicated and expensive, it is preferable to use unsaponified cellulose triacetate after being subjected to a corona discharge treatment in view of the manufacturing process.

The amount of discharge in the corona discharge treatment is not particularly limited, and is preferably in the range of 30 W·min/m ² or more and 300 W·min/m ² or less, and 50 W·min/m ² or more and 250 W·min/m 2 or more. A range of ² or less is more preferable. Within the above range, the adhesion between the protective film and the adhesive can be improved without deteriorating the protective film itself, which is preferable. Here, the amount of discharge is the amount of work performed on the object by corona discharge obtained by the following formula, and the corona discharge power is determined based on this.

The method for producing the polarizing plate is not particularly limited, and the polarizing plate can be produced by bonding a polarizer and a protective film with the radical adhesive composition by a conventionally known method. The applied adhesive develops adhesiveness when irradiated with ultraviolet rays and constitutes an adhesive layer.

When the radical-based adhesive composition is applied, it may be applied to either the protective film or the polarizer, or may be applied to both. The radical adhesive composition is preferably applied so that the thickness of the adhesive layer after drying is more than 0 and 20 μm or less. The thickness of the adhesive layer is adjusted according to the solid content concentration in the adhesive solution and the adhesive application device. Also, the thickness of the adhesive layer can be confirmed by observing the cross section with a scanning electron microscope (SEM). The method of applying the adhesive is also not particularly limited, and various means such as a method of directly loading the adhesive, a roll coating method, a spraying method, and an immersion method are employed.

After applying the adhesive, the polarizer and the protective film are joined by roll lamination or the like.

After bonding as described above, the polarizing plate is irradiated with ultraviolet light to cure the adhesive. The light source of ultraviolet light is not particularly limited, and low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps having an emission distribution at a wavelength of 400 nm or less. etc. are used. The amount of ultraviolet irradiation (integrated light amount) is not particularly limited, and the amount of ultraviolet irradiation in the wavelength range effective for activating the polymerization initiator is preferably 100 mJ/cm ² or more and 2,000 mJ/cm ² or less. . Within this range, the reaction time is suitable, and deterioration of the adhesive itself and the polarizing film due to heat radiated from the lamp and heat generated during polymerization can be prevented.

The polarizing plate may be stored at room temperature (20° C. or more and 25° C. or less, specifically 25° C.) for 16 hours or more and 30 hours or less immediately after ultraviolet irradiation. The completion of the curing completes the polarizing plate.

The present invention provides an image display device comprising a display panel and the polarizing plates on one side or both sides of the display panel.

The present invention provides an image display device comprising a display panel and the polarizing plate on the viewer side of the display panel or on the opposite side of the display panel to the viewer side.

The display panel may be a liquid crystal panel, a plasma panel and an organic light emitting panel. Accordingly, the image display device may be a liquid crystal display device (LCD), a plasma display device (PDP) and an organic EL display (OLED). More specifically, the image display device may be a liquid crystal display device including a liquid crystal panel and polarizing plates provided on both sides of the liquid crystal panel, wherein at least one of the polarizing plates is the It may be a polarizing plate including a polarizer according to an embodiment of the present invention.

Here, the type of liquid crystal panel included in the liquid crystal display device is not particularly limited. For example, passive matrix type panels such as TN (twisted nematic) type, STN (super twisted nematic) type, F (ferroelectric) type, PD (polymer dispersed) type, 2-terminal type, etc. Active matrix type panels such as (two terminal) and three terminal types, IPS (In Plane Switching) type panels, and VA (Vertical Alignment) type panels are all applicable. In addition, other structures constituting the liquid crystal display device, such as the types of upper and lower substrates (e.g., color filter substrates or array substrates), are not particularly limited, and may be any structure known in the art. may be adopted.

(Example)
EXAMPLES Hereinafter, in order to specifically describe the present invention, examples will be given and described in detail. However, embodiments of the invention may be modified in various other forms, and the scope of the invention is not limited to the embodiments described below. The embodiments of the present invention are provided in order that the present invention may be more fully explained to those of average skill in the art.

<Production of Radical Adhesive Composition>
A radical adhesive composition having the composition shown in Table 1 was produced.

<Experimental Example 1: Protective Film Adhesion Test>
Both sides of a polarizer (manufactured by LG CHEM) prepared in advance were coated with the radical-based adhesive composition produced as described above, and a peeling protective film (PET film) was laminated. After that, the polarizer and the protective film for peeling are separated from each other by curing the radical adhesive composition by irradiating ultraviolet rays having a wavelength of 365 nm so that the irradiation amount (integrated light amount) becomes 2,000 mJ/cm ² . It was adhered and cut into a size of 2 cm wide×15 cm long to prepare a polarizing plate sample. Here, the pretreatment conditions for the peeling protective film were changed for each radical adhesive composition. In the pretreatment protective film, the portion to be provided with the radical adhesive composition was subjected to corona treatment with a 10% concentration KOH solution at a temperature of 45°C.

As shown in FIG. 3, one of the protective films for peeling was peeled off at a peeling angle of 90 degrees and a peeling speed of 0.5 cm/sec for 3 cm or more, and the peel force was measured three times and the average value was calculated. An XT Plus texture analyzer (manufactured by TA) was used when measuring the peel strength.

T/T in Table 1 means peeling between the analyzer and the protective peeling film, TAC/Ad means peeling between the adhesive layer and the protective peeling film, PVA/Ad means delamination between the polarizer and the adhesive layer. When peeled between the analyzer and the protective peel film, it is classified as an adhesive with excellent performance.

<Experimental Example 2: Measurement of glass transition temperature and storage modulus after curing>
Both surfaces of a polarizer (manufacturer) prepared in advance were coated with the radical-based adhesive composition produced as described above, and a peeling protective film (PET film) was laminated thereon. After that, the radical-based adhesive composition was cured by irradiating ultraviolet rays with a wavelength of 365 nm so that the irradiation amount (accumulated light amount) was 2000 mJ/cm ² . This was cut into a size of 5.3 mm in width and 4.5 cm in length, and the protective film for peeling was peeled off to obtain a cured product (cured film) of the radical adhesive composition. Using a viscoelasticity measuring device (Dynamic mechanical analyzer: DMA Q800 manufactured by TA Instruments), the cured film was placed so that its long side was in the tensile direction, and the frequency was 1 Hz, the measurement start temperature was −30° C., and the heating rate was The viscoelasticity measurement was performed by setting the temperature to 5°C/min. The glass transition temperature (Tg) was taken as the temperature at which Tan δ reaches its maximum value, and the peak value of Tan δ was taken as its maximum value.

In addition, using DMA Q800 (TA instrument), Temperature sweep test (strain 0.04%, Preload force: 0.05N, Force Track: 125%, Frequency: 1 Hz), 5 ° C./from 0 ° C. to 150 ° C. The storage elastic modulus was measured by raising the temperature at 80° C., and the value measured at 80° C. was read.

<Experimental Example 3: Water resistance evaluation>
Both surfaces of a polarizer (manufacturer) prepared in advance were coated with the radical-based adhesive composition produced as described above, and a peeling protective film (PET film) was laminated thereon. After that, the radical-based adhesive composition was cured by irradiating ultraviolet rays with a wavelength of 365 nm so that the irradiation amount (accumulated light amount) was 2000 mJ/cm ² . This was cut so that the length of each of the absorption axis direction of the polarizer and the direction perpendicular thereto was 150 mm. Then, a pressure-sensitive adhesive was applied to one side of the protective film for peeling, laminated on a glass substrate, and left at 25° C. for 24 hours. After that, the glass plate was left in a water bath at 60° C. for 24 hours and taken out. The appearance of this sample was visually observed, and the presence or absence of color omission of the polarizer and peeling of the film was examined. OK was indicated when there was no color loss or the film was not peeled off, and NO was indicated when there was color loss or the film was peeled off.

<Experimental Example 4: Thermal Shock Evaluation>
Both surfaces of a polarizer (manufacturer) prepared in advance were coated with the radical-based adhesive composition produced as described above, and a peeling protective film (PET film) was laminated thereon. After that, the radical-based adhesive composition was cured by irradiating ultraviolet rays with a wavelength of 365 nm so that the irradiation amount (accumulated light amount) was 2000 mJ/cm ² . This was cut so that the length of each of the absorption axis direction of the polarizer and the direction perpendicular thereto was 150 mm. Then, a pressure-sensitive adhesive was applied to one side of the protective film for peeling, laminated on a glass substrate, and left at 25° C. for 24 hours.

Thereafter, the glass substrate was left at −40° C. for 30 minutes and then at 85° C. for 30 minutes as one cycle, and this cycle was repeated 100 times. A thermal shock is applied, and then it is observed whether or not there is a polarizer crack from the edge of the polarizer in the stretching direction (arrow direction) of the polarizer. was measured. When multiple cracks were observed, the average value was used for evaluation. When no crack occurred or the length of the crack was less than 1 mm, it was indicated as acceptable, and when the length of the crack was 1 mm or more, it was indicated as unacceptable.

<Experimental Example 5: Rigidity Evaluation>
Both surfaces of a polarizer (manufacturer) prepared in advance were coated with the radical-based adhesive composition produced as described above, and a peeling protective film (PET film) was laminated thereon. After that, the radical-based adhesive composition was cured by irradiating ultraviolet rays with a wavelength of 365 nm so that the irradiation amount (accumulated light amount) was 2,000 mJ/cm ² . This was cut into a size of 3 cm in width and 7 cm in length, and the protective film for peeling was peeled off to obtain a cured product (cured film) of the radical adhesive composition.

As shown in FIG. 4, the cured film was bent into a loop and fixed to a viscoelasticity measuring device (Dynamic mechanical analyzer: DMA Q800 manufactured by TA instruments), and the bent surface was pressed with a force of 1 g and 30 m / min, and the thickness was 20 mm. was recorded as the stiffness of the cured film.

<Experimental Example 6: Evaluation of the viscosity of the entire composition>
The viscosity of each composition was evaluated.
Evaluation method:
・Measuring device: BROOKFIELD VISCOMETER DV-II+PRO
・Speed: 90RPM
・Spindle: No. 18

<Experimental Example 7: Viscosity evaluation of urethane acrylate oligomer>
The viscosity at 25°C of each urethane oligomer was evaluated.
・Measuring device: BROOKFIELD VISCOMETER DV-II+PRO
・Speed: 0.01 rpm
・Spindle: No. 18

<Experimental Example 8: Measurement of acid value of urethane acrylate oligomer>
The acid value of urethane acrylate was measured according to the method described above.

The symbols in Tables 1 and 2 are described below.
A: Urethane acrylate oligomer (a): Polyester-based urethane acrylate oligomer B1: Polyfunctional (meth)acrylate monomer whose homopolymer has a glass transition temperature (Tg) of 150°C or higher B2: Glass transition temperature of the homopolymer ( Polyfunctional (meth)acrylate monomer having a Tg) of less than 150° C. C: (meth)acrylate monomer having a hydrophilic functional group D: silane coupling agent E: light scattering agent F: photoinitiator DPGDA: dipropylene Glycol diacrylate (Tg: 102°C)
M370: tris (2-hydroxyethyl) isocyanurate triacrylate (Tg: 225 ° C.)
4-HBA: 4-hydroxybutyl acrylate (Tg: -56°C)
R-604: [2-[1,1-dimethyl-2[(1-oxoallyl)oxy]ethyl]-5-ethyl-1,3-dioxane-5yl]methyl acrylate (Tg: 180° C.)
KBM403: (3-glycidoxypropyl)trimethoxysilane I250: (4-methylphenyl)[4-(2-methylpropyl)phenyl]iodonium hexafluorophosphate TPO: diphenyl(2,4,6-trimethylbenzoyl)- Phosphine oxide DETX: 2,4-diethylthioxanthone

The parts by weight of A, B (B1, B2), C and D mean the parts by weight of each substance with respect to the total weight of 100, which is the total weight of A to D.

The parts by weight of E and F refer to the parts by weight of each substance with respect to the total weight of 100, which is the total weight of A to D.

From the above results, it was confirmed that the radical-based adhesive compositions of Examples 1 and 2 have excellent adhesion to PET films that have not been corona-treated. This is because the radical-based adhesive composition contains a polyester-based urethane acrylate oligomer with a controlled acid value, thereby ensuring excellent adhesion of the adhesive layer to the protective film.

Also, it was confirmed that when the radical-based adhesive compositions of Examples 1 and 2 were applied to the polarizing plate, the heat resistance and water resistance were improved, and the rigidity was improved.

[Appendix]
[Appendix 1]
a polyester-based urethane acrylate oligomer (A) having an acid value of 90 mgKOH/g to 180 mgKOH/g;
a polyfunctional (meth)acrylate monomer (B) whose homopolymer has a glass transition temperature (Tg) of 150° C. or higher;
a (meth)acrylate monomer (C) having a hydrophilic functional group;
A radical adhesive composition comprising a silane coupling agent (D).

[Appendix 2]
The radical-based adhesive composition according to Appendix 1, wherein the polyester-based urethane acrylate oligomer (A) is formed from a composition containing a polyester-based polyol compound, an isocyanate-based compound, and an acrylate-based compound.

[Appendix 3]
The radical adhesive composition according to Appendix 1, wherein the polyester-based urethane acrylate oligomer (A) has a viscosity at 25°C of 1,000 cPs or more and 50,000 cPs or less.

[Appendix 4]
The radical adhesive composition according to Appendix 1, comprising 1 to 20 parts by weight of the polyester-based urethane acrylate oligomer (A) with respect to 100 parts by weight of the entire composition.

[Appendix 5]
The radical adhesive composition according to Appendix 1, further comprising a polyfunctional (meth)acrylate monomer (B2) whose homopolymer has a glass transition temperature (Tg) of less than 150°C.

[Appendix 6]
The radical adhesive composition according to appendix 1, wherein the cured radical adhesive composition has a glass transition temperature of 80° C. or higher and 150° C. or lower.

[Appendix 7]
The radical adhesive composition according to Supplementary Note 1, wherein the radical adhesive composition has a peak value of Tan δ after curing of 0.2 or higher, and a glass transition temperature at the peak value of Tan δ of 90° C. or higher. thing.

[Appendix 8]
The radical adhesive composition according to appendix 1, wherein the radical adhesive composition has a storage elastic modulus at 80°C after curing of 800 Mpa or more and 2,000 Mpa or less.

[Appendix 9]
The radical adhesive composition according to Appendix 1, which does not have an ether bond peak (1,080 cm ⁻¹ ) in the IR spectrum after curing.

[Appendix 10]
The radical adhesive composition according to appendix 1, wherein a cured product of the radical adhesive composition has an adhesive strength of 150 gf/20 mm or more to a polyethylene terephthalate film that has not been pretreated.

[Appendix 11]
The radical adhesive composition according to appendix 1, which has a viscosity of 10 cPs or more and 100 cPs or less at 25°C.

[Appendix 12]
a protective film;
A protective film for a polarizing plate, comprising: an adhesive layer containing a cured product of the radical adhesive composition according to any one of Appendices 1 to 11 on one or both sides of the protective film.

[Appendix 13]
13. The polarizing plate protective film according to Appendix 12, wherein the thickness of the adhesive layer is greater than 0 μm and equal to or less than 20 μm.

[Appendix 14]
13. The protective film for polarizing plate according to Appendix 12, wherein the protective film is a cellulose film.

[Appendix 15]
a polarizer;
and the protective film for a polarizing plate according to Appendix 12, provided on one or both sides of the polarizer.

[Appendix 16]
a display panel;
and the polarizing plate according to Appendix 15 provided on one side or both sides of the display panel.

101, 105 protective film 102, 104 adhesive layer 103 polarizer

Claims (16)

a polyester-based urethane acrylate oligomer (A) having an acid value of 90 mgKOH/g to 180 mgKOH/g;
a polyfunctional (meth)acrylate monomer (B) whose homopolymer has a glass transition temperature (Tg) of 150° C. or higher;
a (meth)acrylate monomer (C) having a hydrophilic functional group;
A radical adhesive composition comprising a silane coupling agent (D). 2. The radical adhesive composition according to claim 1, wherein the polyester-based urethane acrylate oligomer (A) is formed from a composition containing a polyester-based polyol compound, an isocyanate-based compound, and an acrylate-based compound. The radical adhesive composition according to claim 1, wherein the polyester-based urethane acrylate oligomer (A) has a viscosity at 25°C of 1,000 cPs or more and 50,000 cPs or less. 2. The radical adhesive composition according to claim 1, comprising 1 to 20 parts by weight of the polyester-based urethane acrylate oligomer (A) with respect to 100 parts by weight of the entire composition. The radical adhesive composition according to claim 1, further comprising a polyfunctional (meth)acrylate monomer (B2) whose homopolymer glass transition temperature (Tg) is less than 150°C. The radical adhesive composition according to claim 1, wherein the cured radical adhesive composition has a glass transition temperature of 80°C or higher and 150°C or lower. 2. The radical adhesive composition according to claim 1, wherein the radical adhesive composition has a Tan δ peak value of 0.2 or higher after curing, and a glass transition temperature at the Tan δ peak value of 90° C. or higher. Composition. The radical adhesive composition according to claim 1, wherein the storage elastic modulus at 80°C after curing of the radical adhesive composition is 800 Mpa or more and 2,000 Mpa or less. 2. The radical adhesive composition according to claim 1, which does not have an ether bond peak (1,080 cm ⁻¹ ) in the IR spectrum after curing. 2. The radical adhesive composition according to claim 1, wherein the cured radical adhesive composition has an adhesive strength of 150 gf/20 mm or more to a polyethylene terephthalate film that has not been pretreated. The radical adhesive composition according to claim 1, which has a viscosity at 25°C of 10 cPs or more and 100 cPs or less. a protective film;
A protective film for a polarizing plate, comprising an adhesive layer containing a cured product of the radical adhesive composition according to any one of claims 1 to 11 on one or both sides of the protective film. 13. The protective film for polarizing plate according to claim 12, wherein the adhesive layer has a thickness of more than 0 [mu]m and 20 [mu]m or less. 13. The protective film for polarizing plate according to claim 12, wherein said protective film is a cellulose film. a polarizer;
and the protective film for a polarizing plate according to claim 12 provided on one side or both sides of the polarizer. a display panel;
and the polarizing plate according to claim 15 provided on one side or both sides of the display panel.

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