KR20170092958A - Polyester-based primer composition, optical film - Google Patents

Abstract

The optical polyester film according to the present invention is an optical polyester film comprising a primer in which a curing agent having excellent adhesion to a top coating solution used in a prism sheet used in an optical sheet is mixed Wherein the coating liquid comprises 10 to 50 parts by weight of an isocyanate curing agent aqueous dispersion, 1 to 5 parts by weight of a fluorinated surfactant aqueous dispersion, and 0.1 to 10 parts by weight of silica particles, in 100 parts by weight of the heat reactive urethane resin water dispersion, The curing agent is dissociated at 90 to 100 degrees and is characterized in that the isophorone is a trifunctional curing agent using isocyanate (IPDI).

Description

[0001] The present invention relates to an optical polyester film comprising a primer layer excellent in blocking resistance (polyester-based primer composition, optical film)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical polyester film and, more particularly, to an optical polyester film comprising an optical sheet including a primer which is used by mixing a hardening agent having excellent adhesive strength with a top coating liquid used for a prism sheet, To a polyester film for use in the present invention.

In general, the polyester film is excellent in dimensional stability, thickness uniformity, and optical transparency, and is widely used as a material for various industrial materials as well as display devices. Particularly, as interest in liquid crystal display devices, organic light emitting display devices, electronic devices, and the like has rapidly increased recently, research has been actively conducted to replace substrates of these display devices with polyester films instead of glass substrates. This is because replacing a glass substrate with a polyester film can reduce the overall weight of the display device, provide flexibility in design, be strong against impact, and can be manufactured in a continuous process, resulting in higher productivity than a glass substrate .

 BACKGROUND OF THE INVENTION [0002] The present invention relates to a film, in particular, among various uses thereof. Currently, a polyester film which is industrially produced is widely used as a base film for magnetic recording media, various packaging materials and other industrial applications, It is used as material and various post processing materials.

 High glass transition temperature, high light transmittance and scratch resistance of the surface which can withstand the deposition temperature of the transparent electrode for such use, and adhesion with the substrate and the post-coating liquid are required. In addition, in the case of such a polyester film, a process of coating a hard coat layer on the surface is often carried out. The problem with the production of such a polyester film is that the polyester film is deformed by a difference in the coefficient of linear expansion between the polyester film and the hard coat layer Cracking and peeling, and bonding between unreacted materials in the coating layer may cause blocking phenomena occurring between the coating layers.

 In the case of a functional polyester base material, a primer layer is often used with a copolymer polyester resin (binder) which is often excellent in adhesion to a polyester base material. However, such a copolymer polyester base resin is excellent in adhesion to a polyester base film However, when the post-processing such as a prism processing layer, a lens processing layer, an antireflection layer, or a hard coating layer, which is another substrate, is performed, the adhesion is extremely insufficient.

For example, in the case of hard coating, the adhesive strength to the outer layer of the processed surface is improved, but the adhesive strength to the polyester base substrate, which is a base material, is not sufficient. Recently, in order to improve the adhesiveness, a large amount of acryl or urethane resin (including radical), which is generally used for the primer layer, has been used.

The primer used for improving the adhesiveness of the optical polyester film mainly uses a urethane binder, and at the same time, a tin catalyst is used together to improve the reactivity of the urethane binder. Since tin catalysts used together are environmentally regulated substances, researches are under way to replace them. Platinum catalysts are used as catalysts for replacing tin catalysts, but they are costly and cause a rise in product cost.

Korean Patent Publication No. 10-0964707

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an object of providing a primer layer formed by applying a coating liquid containing at least one surface of a thermosensitive urethane resin, an isocyanate hardener, a surfactant and a slip agent, And an object of the present invention is to produce this adhesive layer of an optical polyester film which prevents the blocking phenomenon.

The present invention relates to a polyester film having excellent blocking resistance, which comprises a primer layer formed by applying a coating liquid containing at least one surface of a heat-reactive urethane resin, an isocyanate curing agent, a surfactant and a slipping agent.

A polyester film comprising a polyester-based polymer base film and a primer layer in which a polymer applied on at least one side of the base film is an adhesive layer,

Wherein the primer layer comprises a primer containing 0.1 to 50% of a curing agent based on 100% of a urethane resin.

The primer layer coating solution was prepared by mixing 10 to 50 parts by weight of an isocyanate curing agent aqueous dispersion having a solid content of 40 wt% and 10 to 50 parts by weight of a fluorinated surfactant aqueous dispersion having a solid content of 10 wt% in 100 parts by weight of a thermally reactive urethane resin aqueous dispersion having a solid content of 25 wt% To 5 parts by weight, and 0.1 to 10 parts by weight of silica particles having a solid content of 40% by weight.

Also, the used isocyanate curing agent dissociates at 90 to 100 degrees and is excellent in moisture resistance and blocking effect because it is a three-functional group curing agent using IPDI. If a blocking agent dissociates at a temperature outside the above-mentioned temperature range is used, or if the composition is out of the above composition range, the adhesiveness may be deteriorated and blocking may occur, which may cause problems in handling.

The optical polyester film according to the present invention has a low manufacturing cost due to a primer that mixes a curing agent and has an excellent adhesion with a top coating solution used in a prism sheet.

Further, a primer in which a hardener is mixed instead of a tin catalyst has the effect of an environmental regulatory substitute material.

It will be apparent to those skilled in the art that the present invention is not limited by these embodiments.

Polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, or copolymers whose main component is a constituent component of these resins are used as the base film of the present invention desirable.

In the present invention, the polyester film as the base film is a film having a thickness of 50 탆 or more, preferably 100 to 300 탆. If the thickness of the film is less than 50 탆, the adhesive force with the adhesive layer drops sharply.

The polyester resin may contain various additives. Examples of additives include antistatic agents, UV absorbers, antibacterial agents, stabilizers and the like.

The adhesive layer of the optical polyester film of the present invention is laminated on at least one surface of the polyester film and the adhesive layer is provided on at least one surface of the unstretched or uniaxially stretched polyester film and then stretched in at least one axial direction It is preferable to laminate the substrate by an in-line coating method

The adhesion referred to in the present invention means that the adhesion with the coating layer is 85% or more, preferably 90% or more, and particularly preferably 95% or more.

The adhesiveness is an adhesion property determined from the following formula (1) based on the test method according to 8.5.1 of JIS-K 5400.

Adhesion (%) = (1-peeling area / evaluation area) x 100 (1)

In order to satisfy the above formula (1), it is important to select the type of resin used for the adhesive layer and the refractive index of particles and other additives to be contained in the adhesive layer.

(A), a polyurethane resin (B) and a curing agent (C) are used as the main resin component in the optical polyester film of the present invention. . In the present invention, it is preferable to use an aqueous coating liquid for the coating liquid for forming the adhesive layer.

The copolymerized polyester resin (A) used in the adhesive layer of the present invention preferably contains a dicarboxylic acid component and a branched glycol component as constituent components. Examples of the branched glycol component include 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 2- Methyl-2-propyl-1,3-propanediol, 2-methyl-2-isopropyl-1,3-propanediol, 2-ethyl-2-n-butyl-1,3-propanediol, 2-ethyl- 1,3-propanediol, 2-n-butyl-2-propyl-1,3-propanediol and 2,2-di-n-hexyl- .

In the present invention, it is preferable that the copolymer polyester resin used for the adhesive layer contains a dicarboxylic acid component and a branched glycol component as constituent components. Examples of the branched glycol component include 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 2- Methyl-2-propyl-1,3-propanediol, 2-methyl-2-isopropyl-1,3-propanediol, 2-ethyl-2-n-butyl-1,3-propanediol, 2-ethyl- butyl-1,3-propanediol, 2-n-butyl-2-propyl-1,3-propanediol and 2,2-di-n-hexyl- , But not limited to.

As the dicarboxylic acid component contained as a constituent component in the copolymer polyester-based resin (A), terephthalic acid and isophthalic acid are most preferable. If the amount is small, other dicarboxylic acids, especially diphenylcarboxylic acid and aromatic dicarboxylic acid of 2,6-naphthalenedicarboxylic acid, may be added and copolymerized.

In the present invention, terephthalic acid and isophthalic acid are most preferable as the dicarboxylic acid component contained as a constituent component in the copolymer polyester-based resin. When the amount is small, other dicarboxylic acids, especially diphenylcarboxylic acid and aromatic dicarboxylic acid of 2,6-naphthalenedicarboxylic acid, are applied, but the present invention is not limited thereto.

As the polyurethane resin (B) to be used for the adhesive layer of the optical polyester film of the present invention, various materials used as various types of coating agents such as solvent type, solventless type and aqueous type can be used. In the present invention, for example, as a resin containing a block-type isocyanate group, a heat-reactive water-soluble urethane in which a terminal isocyanate group is blocked with a hydrophilic group (hereinafter referred to as a "block") can be given.

(I) a polyol having at least two active hydrogen atoms in the molecule or a compound having a molecular weight of 20020,000 having at least two active hydrogen atoms in the molecule, (ii) a urethane prepolymer, An organic polyisocyanate having two or more isocyanate groups in the molecule and, if necessary, (iii) a terminal isocyanate group obtained by reacting a chain extender having at least two active hydrogen atoms in the molecule.

A compound generally known as the compound (i) includes two or more hydroxyl groups, carboxyl groups, amino groups, or mercapto groups in the terminal or molecule. Particularly preferred compounds include polyether polyol and polyether ester polyol. .

Examples of the polyether polyol include alkylene oxides such as ethylene oxide and propylene oxide, compounds obtained by polymerizing styrene oxide and epichlorohydrin, or compounds obtained by subjecting them to random polymerization, block polymerization, or addition polymerization to polyhydric alcohol .

Examples of the organic polyisocyanate (ii) include isomerization products of toluylenediisocyanate, aromatic diisocyanates such as 4,4-diphenylmethane diisocyanate, aromatic aliphatic diisocyanates such as xylylene diisocyanate,

Alicyclic diisocyanates such as isophorone diisocyanate and 4,4-dicyclohexylmethane diisocyanate, aliphatic diisocyanates such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate,

May be singly or plurally substituted with trimethylolpropane or the like.

Examples of the chain extender having at least two active hydrogens of (iii) include glycols such as ethylene glycol, diethylene glycol, 1,4-butanediol and 1,6-hexanediol, glycerin, trimethylolpropane and pentaerythritol , Diamines such as ethylenediamine, hexamethylenediamine and piperazine, aminoalcohols such as monoethanolamine and diethanolamine, thiodiglycol such as thiodiethylene glycol, and water.

Based on the urethane resin (B), 10 to 50 parts by weight of an isocyanate curing agent water dispersion having a solid content of 40 wt% and a solid content of 10 wt% 1 to 5 parts by weight of a fluoric surfactant aqueous dispersion, and 0.1 to 10 parts by weight of silica particles having a solid content of 40 wt%.

In addition to urethane resins, thermosetting resins include phenol resins made from phenol and formaldehyde as raw materials, melamine resins obtained by reacting melamine and formaldehyde with weakly alkaline or slightly acidic resins, silicone resins And urea resin obtained by dehydrating and reacting an initial condensate with formaldehyde in carbon dioxide gas or ammonia, and adding pulp, coloring agent or the like.

The room temperature neutralizing agent and the neutral temperature neutralizing agent are preferably 0.1 to 5% based on 0.1 to 30% of the curing agent (C).

Various additives such as an antistatic agent, an ultraviolet absorption inhibitor, an antibacterial agent, a plasticizer, a pigment, an organic, an inorganic filler and a lubricant may be added to the composition of the aqueous coating liquid within a range that does not lose adhesion. Further, since the coating liquid is aqueous, the performance is improved within a range in which the contribution effect is not lost.

The aqueous coating liquid containing the water-soluble copolyester (A) and the polyurethane resin (B) described above is applied to one or both surfaces of the optical polyester film of the present invention.

The aqueous coating liquid may be applied by any known method. For example, a roll coating method, a gravure coating method, a kiss coating method, a roll brush method, a spray coating method, an air knife coating method, a wire bar coating method, a pipe doctor method, an impregnation coating method, And these methods can be performed alone or in combination.

The step of applying the aqueous coating liquid may be an ordinary coating step, that is, an off line process to be applied to a heat-set base film. However, the in-line coating method of applying the aqueous coating liquid during the above-described production process of the base film is preferable. Further, it is more preferable to coat the base film before the crystal orientation is completed. When the above coating liquid is applied to the polyester film base after unstretched or uniaxially stretched and then dried and stretched, only the solvent such as water is removed in the drying step after coating, and the temperature at which the crosslinking reaction of the coating layer does not proceed And time. The drying temperature is preferably 20 to 100 DEG C, and the drying time is preferably adjusted depending on the coating liquid and the application amount, and the product of the temperature (DEG C) and the time (second) is preferably 1000 to 3000.

Specifically, the shielding plate is covered with plenum ducts (hot air discharging portions) arranged at upper and lower parts at regular intervals along the film advancing direction, and the width of the shielding plate is gradually widened along the film advancing direction ), It is preferable that the air volume in the width direction of the film is increased toward the end portion from the central portion of the film, and the temperature in the width direction of the film is increased from the central portion toward the end portion. Further, the temperature in the film width direction may be increased from the center portion toward the end portion by using an infrared heater.

Further, in the present invention, the optical polyester film can be processed so as to obtain a roll having a good roll appearance when rolled up in a roll form, and also maintaining a long-term quality or durability. Likewise, the adhesive film for optical use of the present invention can be processed so as to obtain a roll having good roll appearance when the film is wound into a roll, and also maintaining a long-term quality or durability.

Hereinafter, the present invention will be described in more detail with reference to Example 1. However, these embodiments are only for illustrative purposes and the invention is not limited thereto.

Example

Next, the production method of the adhesive film for optical use of the present invention will be described by taking PET as an example of the base film, but the present invention is not limited to this. In the examples and comparative examples, "part" and "%" are based on weight unless otherwise specified.

Example 1

(1) Adjustment of coating liquid

The coating liquid used in the present invention was prepared by the following method.

(1) 25 parts by weight of an isocyanate curing agent water dispersion having a solid content of 40 wt%, 3 parts by weight of a fluorinated surfactant aqueous dispersion having a solid content of 10 wt%, a solids content of And 5 parts by weight of 40 wt% of silica particles were mixed to prepare a coating liquid.

② The isocyanate curing agent b used is a trifunctional curing agent that dissociates at 90 to 100 degrees and uses IPDI.

Comparative Example 1

3-functional isocyanate curing agent using IPDI dissociated at 90 to 100 ° C. b) A blocking agent (3,5-dimethyl pyrazole) dissociated at 120 ° C. instead of 25 parts by weight of water dispersion Except that an isocyanate curing agent a aqueous dispersion was added , A coating liquid was prepared in the same manner as in Example 1.

Example 2

 A coating liquid was prepared in the same manner as in Example 1, except that an oxazoline curing agent aqueous dispersion was added in place of 25 parts by weight of an isocyanate curing agent aqueous dispersion having a solid content of 40 wt%.

Example 3

 A coating liquid was prepared in the same manner as in Example 1, except that an aqueous dispersion of an aziridine curing agent was added in place of 25 parts by weight of an aqueous dispersion of an isocyanate curing agent having a solid content of 40 wt%.

Example 4

 A coating liquid was prepared in the same manner as in Example 1, except that a water dispersion of a melamine curing agent was added instead of 25 parts by weight of an isocyanate curing agent aqueous dispersion having a solid content of 40 wt%.

Assessment Methods

1. Adhesion to the photocurable acrylic coating layer

The adhesion was evaluated as follows after UV exposure in the film state before top coating.

A) Adhesion at room temperature: Using a crosscutter on the prism top coating surface, make a cutting line of 10 X 10. The distance between each cutting line shall be approximately 1 mm. Rub the tape over the cut line and attach the tape vertically. (Three times)

B) Exposure: The prism top coating surface is exposed to water vapor for about 30 minutes, and then the water is removed. (High temperature and high humidity acceleration test)

C) Alkali resistance: After immersing the specimen in 5% NaOH solution for about 30 minutes, check the adhesive strength at room temperature after adhesion.

D) Adhesion (%) = 100 - Area of top coating layer removed

A UV coating layer of 5 to 35 占 퐉 was formed under the conditions of 40 mJ using a low-pressure Black lamp and 200 mJ / cm2 using a high-pressure mercury lamp on the adhesive layer of the optical adhesive film using a laminating machine. The obtained film was evaluated for adhesion by a test method according to 8.5.1 of JIS-K 5400. More specifically, a cutter guide having a gap of 2 mm was used to form a scratch on 100 matrix structures extending through the adhesive layer to reach the substrate film, and a cellophane adhesive tape (3M company # 720, 24 mm width) And the adhesive properties were measured by the naked eye from the following equation. The results are shown in Table 1 below. ≪ tb > < TABLE >

2. Blocking test

Using a heat-gradient tester, peel off the primer layer at 130-170 ° C for 4 atm for 30 seconds and check whether the primer layers are adhered to each other.

Type of hardener Properties The isocyanate curing agent A Isocyanate curing agent B Oxazoline Azyridine Melamine This adhesive property blocking Example 1 X O X X X 100 Occurrence x Example 2 X X O X X 80 Occurrence (heavy water level) Example 3 X X X O X 70 Occurrence (Kang Su Joon) Example 4 X X X X O 40 Occurrence (Kang Su Joon) Comparative Example 1 O X X X X 95 Occurrence (Kang Su Joon)

1) Isocyanate curing agent A: Using a blocking agent (3,5-dimethyl pyrazole) dissociated at 120 ° C

2) Isocyanate curing agent B: Using a blocking agent dissociated at 90 to 100 ° C

As can be seen from the above Table 1, the optical polyester film according to the present invention was found to have an excellent adhesion of 96% or more to the urethane liquid UV-resin, and the isocyanate curing agent b was found to be in the range of 90 to 100 degrees And since isophorone is a three-functional group hardener using isocyanate (IPDI), it is excellent in moisture resistance and blocking effect.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the present invention as defined by the appended claims and their equivalents. .

Claims (3)

A polyester film comprising a polyester-based polymer base film and a primer layer in which a polymer applied on at least one side of the base film is an adhesive layer,
Wherein the primer layer comprises a heat-reactive urethane resin, an isocyanate curing agent, a fluorine-based surfactant, and silica particles.
The method according to claim 1,
Wherein the primer layer comprises a coating liquid comprising 100 parts by weight of the thermosensitive resin, 10 to 50 parts by weight of an isocyanate curing agent, 1 to 5 parts by weight of a fluorine surfactant, and 0.1 to 10 parts by weight of silica particles. Polyester film.
The method according to claim 1,
Wherein the curing agent is an isocyanate curing agent which is a trifunctional curing agent using isophorone diisocyanate (IPDI) dissociated at 90 to 100 ° C.