KR101613761B1 - Coating method, non-solvent coating composition, coating appratus using inkjet head and pressure-sensitive adhesive layer formed thereby - Google Patents

Abstract

The present invention relates to a solvent-free ultraviolet curing coating method, and it is an object of the present invention to provide an ultraviolet curing coating method which is environmentally friendly and excellent in process efficiency by spraying a solventless coating liquid containing an acrylate partial polymer using an inkjet head, A pressure-sensitive adhesive layer having a uniform thickness can be provided.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating method, a coating method using the ink-jet head, a coating method using the ink-jet head,

The present invention relates to a coating method, a solventless coating liquid composition, a coating apparatus using an ink jet head, and a pressure-sensitive adhesive layer formed thereby.

A coating method for forming a film on the surface of a material is generally divided into a solvent type system and a solventless type system depending on a coating system.

Among them, the solvent-free curing coating method is a method of directly curing and coating a solvent without drying it. Since it does not require a heating or incineration process for aging or removal of solvent as compared with a coating method using a solvent, Coating method.

As a general coating method of the solventless curing coating method, a comma coating method using a comma coater is mainly used. Comma Direct (Comma Reverse) is suitable for coating a coating liquid having a viscosity of about 500 to 500,000 cps at a rate of 0.1 to 100 m / min. Since a clean surface can be obtained and the operation is simple, To general industrial and electronic industries, and chemical industry.

However, in the case of the comma coater method which is mainly used in the solventless curing coating method, when the comma coater rotates due to adsorption between the comma and the coating liquid during formation of the coating layer, the coating liquid rises along with the comma coater. Unlike the coating gap of the comma coater thus determined, the thickness is non-uniformly induced. Particularly, when the thickness is thinned to 10 to 50 占 퐉, the non-uniformity of the thickness becomes worse.

In addition, when a solventless curing coating is performed using a comma coating method, it is impossible to form a coating layer of various patterns, which may cause costly problems.

Therefore, there is a need to study a solvent-free curing coating method which can form a coating layer having a uniform thickness even if a thin coating layer is formed, and can form a coating layer of a wider variety of patterns.

The present invention provides a coating method, a solventless coating liquid composition, a coating apparatus using the ink jet head, and a pressure-sensitive adhesive layer formed thereby.

One embodiment of the present invention includes a coating layer forming step of forming a coating layer by spraying a solventless coating liquid through an inkjet head; And a curing step of ultraviolet curing the coating layer, wherein the solventless coating liquid comprises an acrylate partial polymer.

Another embodiment of the present invention provides a pressure-sensitive adhesive layer formed through a coating method according to embodiments of the present invention.

Yet another embodiment of the present invention provides a solventless coating composition composition usable in coating methods according to embodiments of the present invention.

According to another embodiment of the present invention, there is provided a coating unit comprising an ink jet head filled with a solventless coating liquid; A transporting unit positioned below the inkjet head and transporting the substrate; And a hardened portion located on one side of the coating portion along an upper portion of the transfer portion and a transfer direction of the substrate, wherein the solventless coating liquid comprises an acrylate partial polymer.

The present invention relates to a coating method and, more particularly, to an eco-friendly and highly efficient UV curable coating method capable of forming a coating layer having a uniform thickness by spraying a solventless coating liquid containing an acrylate partial polymer using an ink jet head . In addition, it is possible to form a coating layer having various patterns, and it is possible to provide a coating method capable of coating a wide area even with a small amount of coating liquid, thereby reducing the cost, and capable of introducing a functional ingredient into a specific portion.

FIG. 1 is a flowchart sequentially illustrating a UV-free coating method according to the present invention.
2 is a perspective view showing a coating apparatus according to the present invention.
3 is a plan view showing the thickness measurement point of the coating layer.

The present invention relates to a coating method. Exemplary coating methods include a coating layer forming step of forming a coating layer by spraying a solventless coating liquid through an inkjet head; And a curing step of ultraviolet curing the coating layer, wherein the solventless coating liquid may comprise an acrylate partial polymer.

The coating method can be effectively applied, for example, in an adhesive coating applied to various optical devices or parts or display devices or parts. Particularly, the coating method of the present invention can be effectively applied to the production of an adhesive film which requires a complicated pattern coating or has a thin thickness and excellent thickness uniformity.

Hereinafter, the coating method of the present invention will be described in detail.

Figure 1 is an exemplary flow chart showing the coating method according to the present invention in sequence.

As shown in FIG. 1, the coating method according to the present invention may include a coating layer forming step (S100) and a curing step (S200).

The coating layer forming step (S100) is a step of applying a non-solvent type coating liquid for ultraviolet curing coating, and the solventless coating liquid may be applied on a substrate through an ink jet head.

The non-solvent type coating liquid means a coating liquid composition in which the coating liquid does not contain a solvent such as an organic solvent or an aqueous solvent. Since the coating liquid composition does not contain a solvent, it is possible to prevent generation of bubbles and leveling caused by the volatilization process of the solvent, and a volatilization process of the solvent is not required, so that the process efficiency is improved, No pollution is caused.

In one example, the viscosity of the solventless coating solution may range from about 5 cps to about 20 cps. For example, 7 to 15 cps, 12 to 18 cps, and 9 to 16 cps, but is not limited thereto. When the solventless coating liquid has a viscosity within the above-mentioned range, the nozzle is not clogged in the ink jet head and the discharge can be smoothly performed.

The solventless coating liquid may comprise, for example, an acrylate partial polymer. The acrylate partial polymer may have a low glass transition temperature (Tg) and may serve to impart adhesive properties after coating. In addition, since it is not necessary to separately dilute the low-viscosity free monomer in order to lower the viscosity, it is possible to discharge the monomer directly, thereby improving the economical efficiency of the process.

 The acrylate partial polymer means a polymer in which an acrylate is partially polymerized and includes, for example, butyl acrylate, isobornyl acrylate, 2-hydroxyl butyl acrylate, 2-hydroxymethyl acrylate, 2-ethyl At least one substance selected from the group consisting of hexyl acrylate, tert-butyl acrylate, methyl acrylate, acrylic acid, benzyl acrylate, methyl methacrylate, 2-hydroxyl ethyl acrylate and 2- But are not limited to, copolymers polymerized through radical initiators.

In addition, the acrylate partial polymer may have a molecular weight of about 10,000 to about 10. For example, 20,000 to 60,000, 40,000 to 90,000, 30,000 to 70,000, 50,000 to 80,000, and 5,000 to 6, but the present invention is not limited thereto. Within the above-mentioned range, it is possible to prepare a solvent-free coating liquid having appropriate tackiness. If the molecular weight is less than 10,000, coating durability may be adversely affected when a coated adhesive is applied to a display such as a polarizing plate. If the molecular weight exceeds 100,000, a free monomer having a low viscosity is artificially diluted to lower the viscosity The polymer resin is strongly adsorbed on the nozzle surface, which may interfere with continuous ink ejection.

In order to control the molecular weight of the acrylate partial polymer, for example, when the radical reaction is suppressed by a method such as oxygen injection after an appropriate level of reaction, the acrylate partial polymer in which the polymerized oligomer material and the acrylate free monomer are mixed Can be obtained.

The polymerization degree of the acrylate partial polymer may be 10% or more. When the degree of polymerization is less than 10%, the molecular weight of the acrylate partial polymer is too small, which may adversely affect the durability of the display product in which the pressure-sensitive adhesive is used.

The content of the acrylate partial polymer may be 80 to 90 parts by weight based on 100 parts by weight of the solventless coating solution. For example, the solvent may be used in an amount of 82 to 86 parts by weight, 84 to 88 parts by weight and 85 to 87 parts by weight based on 100 parts by weight of the solventless coating solution. It is possible to form a pressure-sensitive adhesive layer having excellent tackiness within the above-mentioned range.

The coating layer of the coating layer forming step (S100) may be, for example, a pattern coating layer. The " pattern coating layer " means a coating layer having a regular and / or irregular pattern.

The pattern coating layer may be formed, for example, by discharging the non-solvent coating liquid through an ink jet head while controlling the discharge angle, amount, pressure and speed.

In one example, as described above, the additive may be introduced into a specific portion of the coating layer upon formation of the pattern coating layer. As the above-mentioned " additive " is added to impart specific properties, for example, a silane coupling agent capable of enhancing the bonding force between the coating liquid compositions, a tackifier capable of imparting tackiness to the coating layer, An isocyanate crosslinking agent or an epoxy crosslinking agent capable of curing the coating liquid composition, and the like. For example, when a silane-based coupling agent is introduced into only a corner portion of a display product such as a polarizing plate through a pattern coating, durability enhancement can be induced while using a small amount of a coupling agent.

Examples of the method for introducing the additive into a specific portion of the pattern coating layer include a method of adding an additive to the solventless coating liquid when the inkjet head passes through a specific portion or a method of adding an additive to the solventless coating liquid composition itself, A method of discharging only a specific portion after filling the head, and the like.

When a solventless coating solution for UV curing coating is applied through the inkjet head, a coating layer having a uniform thickness can be formed. In particular, even if a coating layer is formed with a thickness of 1 to 50 탆, the standard deviation of the thickness is 0 Mu] m to 2 [mu] m. Furthermore, even when a thin coating layer having a thickness of 5 占 퐉 or less is formed, a large area can be coated with the same amount of a solventless coating liquid as compared with coating with a comma coater, resulting in cost reduction.

The curing step (S200) is a step of curing the coating layer formed in the coating layer forming step (S100), and the method of curing the solventless coating solution of the present invention is also not particularly limited. For example, the acrylate partial polymer And a suitable aging process to allow the crosslinking agent to react, or irradiation of light capable of inducing polymerization reaction of the photopolymerizable compound.

In one example, the curing step may be ultraviolet curing, and the irradiation of the light may be performed, for example, by ultraviolet irradiation or the like. Exemplary lamps for ultraviolet irradiation include means such as a plurality of ultraviolet lamps arranged in a plurality of rows and columns, a high-pressure mercury lamp, a black light including an ultraviolet ray transmission filter and a stabilizer, a non-electrode lamp, or a xenon lamp Ultraviolet irradiation may be performed, but the present invention is not limited thereto. The irradiation dose at the time of ultraviolet ray hardening is not particularly limited as long as it is controlled to such an extent that sufficient curing can be achieved without impairing all the physical properties. For example, when the illuminance is 50 mW / cm ² To 1,000 mW / cm ² , a light quantity of 50 mJ / cm ² To 1,000 mJ / cm < ² >.

In this specification, the term " ultraviolet ray " means a generic term of electromagnetic waves having a wavelength of 10 to 400 nm.

The curing step (S200) may be cured by various methods known in the art, but may be carried out, for example, in the following manner.

In one example, the one immediately after the discharge as the light quantity of the initial 50 to 100 mJ / cm ^2, so to stop the flow of the discharged solvent-free coating composition from the ink-jet head primary provisionally hardened, from 100 to 300 mJ / cm ² The second light curing step is carried out at a light amount to obtain a fully cured pressure-sensitive adhesive layer. The term " primary hardening " means that a spot curing machine is mounted on the side of the inkjet head ejection opening to temporarily cure the solventless coating liquid immediately after being discharged onto the coating layer, and the term "hardening" It means hardening. The term " secondary photocuring " means a hardening step in which the primary hardened composition is completely hardened to the inside of the composition, which is hardened only at the surface with high light intensity).

In yet another example, after completely dispensing the solventless coating solution through an inkjet head for full curing, the coating solution is sprayed at 50 to 300 mJ / cm < ² > Ultraviolet rays of about the light quantity are irradiated once to obtain a fully cured pressure-sensitive adhesive layer.

Another embodiment of the present invention relates to a solventless coating composition used in the coating method.

The solventless coating composition may comprise an acrylate partial polymer. When the acrylate partial polymer is included, the same effect as described in the coating method described above can be expected.

As described above, the polymerization degree of the acrylate partial polymer may be 10% or more.

The acrylate partial polymer may have a molecular weight of 10,000 to 10. When an acrylate partial polymer having a molecular weight in the range of 10,000 to 100,000 is contained, the same effect as described in the above-mentioned coating method can be expected.

The content of the acrylate partial polymer may be 80 to 90 parts by weight based on 100 parts by weight of the solventless coating solution. Within the content range of such an acrylate partial polymer, the same effect as described in the above-mentioned coating method can be expected.

The range of viscosity of the solventless coating composition is suitable for ejection through an inkjet head when the viscosity is about 5 cps to about 20 cps.

In addition, one exemplary embodiment of the solventless coating composition may include additives. The additive may be, for example, a silane coupling agent, a tackifier, a polyol, an isocyanate crosslinking agent or an epoxy crosslinking agent, and the effect is the same as that described in the above-mentioned pattern coating layer.

Another embodiment of the present invention relates to a coating apparatus using an ink jet head.

2 is a perspective view showing a coating apparatus according to the present invention.

As shown in FIG. 2, the coating apparatus of the present invention includes a coating portion 100, a transfer portion 200, and a hardening portion 300.

The coating unit 100 may include an inkjet head 110 filled with a solventless coating liquid 111. In the coating method described above, a solventless coating solution for ultraviolet curing coating 111), it is possible to form a coating layer having a uniform thickness.

The solventless coating liquid 111 filled in the ink jet head 110 of the coating unit 100 may include an acrylate partial polymer. The molecular weight, degree of polymerization, and the content of the acrylate partial polymer may be determined by the coating method and / The same effects as described in the coating method and the coating solution composition can be expected through the same.

The inkjet head 110 can be used without limitation as long as it is a conventional inkjet head. For example, the inkjet head 110 can be dispensed by applying the solventless coating liquid 111 in a heated state at about 50 to about 90 캜.

For example, the inkjet head 110 may include a filling part for filling the solventless coating solution 111, a sensor for sensing an electrical signal, and at least one or more nozzles through which the solventless coating solution is discharged. And may be arranged in parallel to the lower surface of the head 110.

The transfer unit 200 is positioned below the inkjet head 110 and serves to transfer the substrate 400.

The conveyance unit 200 may be a variety of conveyance means known in the art. For example, a conveyor belt and a roller combined unit may be used, but the present invention is not limited thereto.

The substrate 400 is transferred to the hardening unit 300 after passing through the coating unit 100 by the transfer unit 200. The substrate 400 is a base material for forming a coating of the solventless coating liquid 111, and may be a flat plate or a curved plate.

The hardening unit 300 hardens the solventless coating liquid 111 of the substrate 400 that has passed through the coating unit 100 through the transfer unit 200 to form a coating layer.

As described above, the curing unit 300 may be formed of various means capable of curing the coating layer, and the exemplary curing unit of the present invention may be an ultraviolet irradiation lamp 310. For example, the ultraviolet irradiation lamp 310 may include a plurality of ultraviolet lamps arranged in a plurality of rows and columns, a high-pressure mercury lamp, a black light, an electrodeless lamp, or a xenon lamp composed of a ultraviolet transmission filter and a stabilizer But is not limited thereto.

The hardening part 300 may be positioned on the upper part of the transfer part 200 and on one side of the coating part 100. However, after the substrate 400 passes the coating part 100, the hardened part 300 enters the hardening part 300 It may be located at one side of the coating unit 100 along the transport direction of the substrate 400.

The curing process in the curing unit 300 may be performed in the same manner as the curing process S200 described in the coating method.

Another embodiment of the present invention relates to the pressure-sensitive adhesive layer prepared by the coating method, the coating liquid composition and the coating apparatus.

The pressure-sensitive adhesive layer can be formed by curing the above-described solventless coating solution composition according to the present invention by the above-described coating method or coating apparatus. Therefore, the individual components contained in the pressure-sensitive adhesive layer, the uniform thickness of the pressure-sensitive adhesive layer, and the like are the same as in the description of the pressure-sensitive adhesive composition.

Further, the thickness of the pressure-sensitive adhesive layer is not particularly limited, but the thickness of the pressure-sensitive adhesive layer may be about 1 탆 to about 50 탆. For example, it may be 2 탆 to 30 탆, 10 탆 to 40 탆, 20 탆 to 35 탆, and 25 탆 to 35 탆, but is not limited thereto. Within this thickness range, it is possible to make the thickness of the adhesive film used for mobile or TV thinner. Further, even if the pressure-sensitive adhesive layer formed by the present invention is coated with a thin thickness of 1 to 50 탆, the coating layer can be formed uniformly with a standard deviation of thickness of 0 탆 to 2 탆.

Further, the pressure-sensitive adhesive layer of another embodiment of the present invention may further comprise a substrate, and the pressure-sensitive adhesive layer may be formed on one side or both sides of the substrate. As described above, the pressure-sensitive adhesive layer formed by curing the solvent-free coating composition may be formed to have a uniform thickness even if it is manufactured to have a small thickness. Accordingly, the pressure-sensitive adhesive layer can be effectively applied to various optical devices or parts, display devices or parts. In particular, transparent materials; And the pressure-sensitive adhesive layer of the present invention formed on the transparent substrate can be effectively used for a polarizing plate, a retardation plate, an optical compensation film, a reflection sheet, and a brightness enhancement film for use in liquid crystal display devices and the like.

However, the use of the pressure-sensitive adhesive layer is not limited to the above-mentioned applications, and various industrial sheets such as protective films, cleaning sheets, reflective sheets, structural adhesive sheets, photographic adhesive sheets, And can be effectively used for an adhesive product for electronic parts or an adhesive for electronic parts. Further, the pressure-sensitive adhesive layer of the present invention can be applied to a laminate product of a multilayer structure, a general commercial pressure-sensitive adhesive sheet product, a medical patch, a heat-activated pressure-sensitive adhesive and the like.

[Example]

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples, but the scope of the present invention is not limited by the following examples.

Manufacturing example  One. Acrylate  Preparation of Solvent-Free Coating Solution (A1) Containing Partial Polymer

88 g of an acrylate partial polymer having a molecular weight of 80,000 (polymerization degree: 35%) obtained by radical polymerization after mixing 80% by weight of butyl acrylate and 20% by weight of isobornyl acrylate, 88 g of 1-hydroxycyclohexyl phenyl ketone (I- 184), 5 g of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) and 2 g of 1,6-hexanediol diacrylate as a crosslinking agent were mixed and stirred in a stirrer at room temperature for 5 minutes to prepare a solventless coating solution .

Manufacturing example  2. Acrylate  Preparation of Solventless Coating Solution (A2) Containing Partial Polymer

The procedure of Production Example 1 was repeated except that 88 g of an acrylate partial polymer having a molecular weight of 90,000 and a radical polymerization of 30% by weight of butyl acrylate and 70% by weight of isobornyl acrylate was used (polymerization degree: 40%). To prepare a solventless coating solution.

Manufacturing example  3. Acrylate  Preparation of Solvent-Free Coating Solution (A3) Containing Partial Polymer

In the same manner as in Production Example 1 except that 88 g of an acrylate partial polymer having a molecular weight of 80,000 and a radical polymerization of 35% by weight of butyl acrylate and 40% by weight of isobornyl acrylate was used in Production Example 1, To prepare a coating solution.

Manufacturing example  4. Acrylate  Preparation of Solventless Coating Solution (A4) Containing Partial Polymer

In the same manner as in Preparation Example 1 except that 88 g of an acrylate partial polymer having a molecular weight of 90,000 and a radical polymerization of 30 weight% of butyl acrylate and 60 weight% of isobornyl acrylate was used, To prepare a coating solution.

Manufacturing example  5. Acrylate  Preparation of solvent-free coating solution (A5) containing a partial polymer

The same procedure as in Production Example 1 was carried out except that 88 g of an acrylate partial polymer having a molecular weight of 300,000 and a radical polymerization of 30% by weight of isobornyl acrylate and 80% by weight of butyl acrylate were used in the preparation example 1, To prepare a solventless coating solution.

Manufacturing example  6. Acrylate  Preparation of Solvent-Free Coating Solution (A6) Containing Partial Polymer

The procedure of Production Example 1 was repeated except that 88 g of butyl acrylate and 20% by weight of isobornyl acrylate were mixed and 88 g of an acrylate partial polymer having a molecular weight of 5,000 (polymerization degree: 10%) obtained by radical polymerization was used. To prepare a solventless coating solution.

Manufacturing example  7. Acrylate  Preparation of Solventless Coating Solution (B1) without Partial Polymer

15 g of 2- (2-ethoxyethoxy) ethyl acrylate, 10 g of 2-hydroxyethyl methacrylate, and 5 g of methyl methacrylic acid, 35 g of urethane acrylate, and 20 g of epoxy acrylate 5 g of 1-hydroxycyclohexyl phenyl ketone (I-184), 5 g of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) and 5 g of bisphenol-A cyanate ester as an additive were mixed After that, the mixture was placed in a stirrer and stirred at room temperature for 5 minutes to prepare a solventless coating solution.

Manufacturing example  8. Acrylate  Preparation of Solventless Coating Solution (B2) without Partial Polymer

Except that an acrylate monomer mixture in which 15 g of 2- (2-ethoxyethoxy) ethyl acrylate, 5 g of 2-hydroxyethyl methacrylate and 10 g of methyl methacrylic acid was used in place of the acrylate monomer mixture in Production Example 7 A solventless coating solution was prepared in the same manner as in Preparation Example 7.

Manufacturing example  9. Acrylate  Preparation of solventless coating solution (B3) containing no partial polymer

In Production Example 7, a mixture of 5 g of 2- (2-ethoxyethoxy) ethyl acrylate, 10 g of 2-hydroxyethyl methacrylate and 15 g of methyl methacrylic acid, 35 g of urethane acrylate, Was prepared in the same manner as in Preparation Example 7, except that an oligomer mixture was used.

Manufacturing example  10. Acrylate  Preparation of solventless coating solution (B4) containing no partial polymer

5 g of 1-hydroxycyclohexyl phenyl ketone (I-184), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) as a photoinitiator and 50 g of urethane acrylate and 35 g of epoxy acrylate were mixed. And 5 g of bisphenol-A cyanate ester as an additive were mixed, and then a solventless coating solution was prepared in the same manner as in Production Example 7.

Example  One

The pressure-  Produce

The solventless coating solution (A1) prepared in Preparation Example 1 was filled in a coating machine equipped with an ink jet head and coated, and then cured by irradiating ultraviolet rays for 3 minutes at a light amount of 250 mJ / cm ^{2 with} a UV light irradiator To thereby produce a pressure-sensitive adhesive layer having a thickness of 28 mu m.

Example  2

A pressure-sensitive adhesive layer having a thickness of 28 탆 was prepared in the same manner as in Example 1, except that the solvent-free coating solution (A2) prepared in Preparation Example 2 was used.

Example  3

A pressure-sensitive adhesive layer having a thickness of 28 占 퐉 was prepared in the same manner as in Example 1, except that the solvent-free coating solution (A3) prepared in Preparation Example 3 was used.

Example  4

A pressure-sensitive adhesive layer having a thickness of 28 占 퐉 was prepared in the same manner as in Example 1 except that the solvent-free coating liquid (A4) prepared in Preparation Example 4 was used.

Comparative Example  One

A pressure-sensitive adhesive layer having a thickness of 28 占 퐉 was prepared in the same manner as in Example 1, except that a coating layer was formed using a comma coater instead of the inkjet head.

Comparative Example  2

A pressure-sensitive adhesive layer having a thickness of 28 占 퐉 was prepared in the same manner as in Example 2, except that a coating layer was formed using a comma coater instead of the inkjet head.

Comparative Example  3

A pressure-sensitive adhesive layer having a thickness of 28 占 퐉 was prepared in the same manner as in Example 3, except that a coating layer was formed using a comma coater instead of the inkjet head.

Comparative Example  4

A pressure-sensitive adhesive layer having a thickness of 28 占 퐉 was prepared in the same manner as in Example 4, except that a coating layer was formed using a comma coater instead of the inkjet head.

Comparative Example  5

A pressure-sensitive adhesive layer having a thickness of 28 占 퐉 was prepared in the same manner as in Example 1, except that the solvent-free coating solution (A5) prepared in Preparation Example 5 was used.

Comparative Example  6

A pressure-sensitive adhesive layer having a thickness of 28 占 퐉 was prepared in the same manner as in Example 1, except that the solvent-free coating liquid (A6) prepared in Preparation Example 6 was used.

Comparative Example  7

A pressure-sensitive adhesive layer having a thickness of 28 占 퐉 was prepared in the same manner as in Example 1, except that the solvent-free coating solution (B1) prepared in Preparation Example 7 was used.

Comparative Example  8

A pressure-sensitive adhesive layer having a thickness of 28 탆 was prepared in the same manner as in Example 1, except that the solvent-free coating liquid (B2) prepared in Preparation Example 8 was used.

Comparative Example  9

A pressure-sensitive adhesive layer having a thickness of 28 탆 was prepared in the same manner as in Example 1, except that the solvent-free coating liquid (B3) prepared in Preparation Example 9 was used.

Comparative Example  10

A pressure-sensitive adhesive layer having a thickness of 28 탆 was prepared in the same manner as in Example 1, except that the solvent-free coating liquid (B4) prepared in Preparation Example 10 was used.

Test Example

The properties of the pressure-sensitive adhesive layer prepared in Examples and Comparative Examples were evaluated in the following manner.

Measuring method 1. Adhesion and Jetting  Measure

The nozzle clogging was measured relative to the amount of jetting when the jetting was attempted for 2 hours at intervals of 10 minutes in order to determine whether the adhesive layer of the coated pressure-sensitive adhesive layer was clogged or not. The jetting ability was very good when there was no change with time, and it was evaluated as good, normal, and poor according to the degree of jittering with time. Tackiness was assessed as relatively good, good, moderate, and poor with Tacky using thumbs.

The evaluation criteria for adhesiveness and jetting property are as follows.

◎: Very good

○: Good

△: Normal

Poor: Poor

Measurement method 2. Measurement of standard deviation of thickness

3 is a plan view showing the thickness measurement point of the coating layer.

3, the thickness of each measurement point 510 of the coating layer 500 was measured using a thickness gauge, and the standard deviation sigma of each thickness was calculated by the following equation (1).

[Equation 1]

Standard deviation σ = √ {(Σ (x _k -m) ² ) / n

X _k is the thickness of each point, m is the average, and n is the number of points measured.

Measurement method 3. Measurement of durability

In order to measure the durability of the pressure-sensitive adhesive coated by the ink-jet method, the polarizer used in the LCD display product was adhered onto the substrate using the pressure-sensitive adhesive of Examples 1 to 4 and Comparative Examples 1 to 9, After 500 hours of incubation, the appearance of the polarizing plate was visually confirmed. The durability evaluation criteria of the pressure-sensitive adhesive are as follows.

○: The same as the initial attachment state

X: As the time passes, the phenomenon that the pressure-sensitive adhesive and the polarizing plate are separated from the corners of the polarizing plate is visible to the naked eye, or when the phenomenon that the polarizing plate of a certain area is separated from the adhesive layer is visually confirmed

Table 1 below compares the adhesive properties, the jetting properties and the standard deviation of thickness of the pressure-sensitive adhesive compositions of Examples 1 to 4 and Comparative Examples 1 to 10 according to the above method.

Furtherance
cotter
Stickiness
Jetting ability Standard deviation of thickness (탆)
durability
Example 1 Acrylate partial polymer having a molecular weight of 80,000: Photoinitiator: Additive = 88: 10: 2
Inkjet
◎
○
2
○

Example 2 Acrylate partial polymer having a molecular weight of 90,000: Photoinitiator: additive = 88: 10: 2
Inkjet
△
○
1.5
○

Example 3 Acrylate partial polymer having a molecular weight of 80,000: Photoinitiator: Additive = 88: 10: 2
Inkjet
○
○
One
○

Example 4 Acrylate partial polymer having a molecular weight of 90,000: Photoinitiator: additive = 88: 10: 2
Inkjet
△
○
One
○
Comparative Example 1 Acrylate partial polymer having a molecular weight of 80,000: Photoinitiator: Additive = 88: 10: 2
Comma Coater
◎
-
15
○

Comparative Example 2 Acrylate partial polymer having a molecular weight of 90,000: Photoinitiator: additive = 88: 10: 2
Comma Coater
△
-
14
○

Comparative Example 3 Acrylate partial polymer having a molecular weight of 80,000: Photoinitiator: Additive = 88: 10: 2
Comma Coater
○
-
15
○

Comparative Example
4 Acrylate partial polymer having a molecular weight of 90,000: Photoinitiator: additive = 88: 10: 2
Comma Coater
△
-
13
○

Comparative Example 5
Acrylate partial polymer having a molecular weight of 300,000: Photoinitiator: additive = 88: 10: 2

Inkjet

◎


×
Not measurable
(Not jetting)
Not rated
(Not jetting)
Comparative Example 6 Acrylate Partial Polymer with Molecular Weight 5000: Photoinitiator: Additive = 88: 10: 2
Inkjet
△
○

2
×
Comparative Example 7 Acrylate-based monomer mixture: urethane or epoxy-based oligomer mixture: photoinitiator: additive = 30: 55: 10: 5
Inkjet
×
△
4
Not rated
(No stickiness)
Comparative Example 8 Acrylate-based monomer mixture: urethane or epoxy-based oligomer mixture: photoinitiator: additive = 30: 55: 10: 5
Inkjet
×
△
5
Not rated
(No stickiness)
Comparative Example 9 Acrylate-based monomer mixture: urethane or epoxy-based oligomer mixture: photoinitiator: additive = 30: 55: 10: 5
Inkjet
×
△
4
Not rated
(No stickiness)
Comparative Example 10
Urethane or epoxy oligomer: photoinitiator: additive = 85: 10: 5
Inkjet
×
× Not measurable
(Not jetting) Not rated
(No stickiness, no jetting)

As shown in Table 1, in Examples 1 to 4 in which the pressure-sensitive adhesive layer was formed using the ink-jet head of the solventless coating solution (A1) or the solventless coating solution (A4) according to the present invention, , It was evaluated that it had a uniform thickness and excellent stickiness and no clogging of the ink jet head.

On the other hand, as shown in Comparative Examples 1 to 4, when coated with a comma coater, the adhesion was excellent and durability was secured when the coated pressure-sensitive adhesive was applied to the polarizing plate, but the standard deviation of the thickness was large, It is difficult to form a surface. When the thickness of the coated adhesive layer is not uniform, the thickness of the product is uneven when the actual display product is applied, and the defective product is produced, so that it can not be applied to the actual process.

Further, as shown in Comparative Examples 5 and 6, Comparative Example 5 including an acrylate partial polymer having a molecular weight of 100,000 or more, although containing an acrylate partial polymer, exhibited excellent adhesiveness but found a problem that the ink jet head was clogged, Comparative Example 6 containing an acrylate partial polymer having a molecular weight of 10,000 or less has excellent jetting property but has poor durability as a point spreading agent when applied to a polarizing plate and thus has a problem in that it is practically used as a pressure sensitive adhesive for a display product appear.

In addition, as can be seen from Comparative Examples 7 to 10, in the case of the solventless coating solution containing no acrylate partial polymer according to the present invention, the jetting property was somewhat lowered and it was confirmed that no urethane or epoxy oligomer adhered thereto have.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be appreciated that other embodiments are possible. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

S100: Coating layer formation step
S200: Curing step
100: coating part 110: ink jet head 111: solventless coating liquid
200:
300: hardened portion 310: ultraviolet ray lamp
400: substrate
500: Coating layer 510: Thickness measuring point

Claims (19)

A coating layer forming step of forming a coating layer by spraying a solventless coating liquid through an inkjet head; And
And a curing step of ultraviolet curing the coating layer,
Wherein the solventless coating liquid comprises an acrylate partial polymer having a molecular weight of 10,000 to 100,000. delete delete 2. The composition of claim 1, wherein the acrylate partial polymer is selected from the group consisting of butyl acrylate, isobornyl acrylate, 2-hydroxyl butyl acrylate, 2-hydroxymethyl acrylate, 2-ethylhexyl acrylate, Wherein at least one substance selected from the group consisting of acrylic acid, acrylic acid, benzyl acrylate, methyl methacrylate, 2-hydroxyl ethyl acrylate and 2-phenoxy acrylate is polymerized. The coating method according to claim 1, wherein the viscosity of the solventless coating liquid is 5 cPs to 20 cPs. The coating method according to claim 1, wherein the coating layer in the coating layer forming step is a pattern coating layer. The coating method according to claim 6, wherein at least one additive selected from the group consisting of a silane-based coupling agent, a tackifier, a polyol, an isocyanate crosslinking agent and an epoxy crosslinking agent is introduced into the pattern coating layer. The coating method according to claim 1, wherein the curing step is ultraviolet curing at a light amount of 50 mJ / cm ² to 1,000 mJ / cm ² . 9. A pressure-sensitive adhesive layer formed by the coating method according to any one of claims 1 to 8. A solvent-free coating composition for ink-jet coating comprising an acrylate partial polymer having a molecular weight of 10,000 to 100,000. delete 11. The composition of claim 10, wherein the acrylate partial polymer is selected from the group consisting of butyl acrylate, isobornyl acrylate, 2-hydroxyl butyl acrylate, 2-hydroxymethyl acrylate, 2-ethylhexyl acrylate, Acrylate, acrylic acid, benzyl acrylate, methyl methacrylate, 2-hydroxyl ethyl acrylate, and 2-phenoxy acrylate are polymerized in the nonaqueous coating liquid composition for inkjet coating. 11. The composition of claim 10 wherein the viscosity of the coating fluid composition is from 5 cPs to 20 cPs. 11. The composition of claim 10 wherein the degree of polymerization of the acrylate partial polymer is at least 10%. A coating portion including an ink jet head filled with a solventless coating liquid;
A transfer unit positioned below the inkjet head and transferring the substrate; And
And a hardening portion located on one side of the coating portion along an upper portion of the transfer portion and a transfer direction of the substrate,
Wherein the solventless coating liquid comprises an acrylate partial polymer having a molecular weight of 10,000 to 100,000. delete The coating apparatus according to claim 15, wherein the ink jet head of the coated portion is heated to 50 to 90 캜. 16. The coating apparatus according to claim 15, wherein the hardening unit comprises an ultraviolet irradiation lamp. The coating apparatus as claimed in claim 18, wherein the ultraviolet irradiation lamp is at least one of a black light, an electrodeless lamp, or a xenon lamp, which is composed of an ultraviolet lamp, a high-pressure mercury lamp, an ultraviolet transmission filter and a stabilizer.

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