WO2018084527A1 - Method for manufacturing adhesive film - Google Patents

Abstract

The present application relates to a method for manufacturing an adhesive film. According to one embodiment of the present application, provided is a method for manufacturing an adhesive film, comprising the steps of: coating, on at least one surface of a substrate layer, an adhesive composition containing an isocyanate-based compound, a metal compound, and an acrylic polymer; and forming an adhesive layer by performing drying at a temperature of 100°C or higher.

Description

Manufacturing method of adhesive film

Cross Citation with Related Applications

This application claims the benefit of priority based on Korean Patent Application No. 10-2016-0146413 dated November 04, 2016 and Korean Patent Application No. 10-2017-0142311 dated October 30, 2017. All contents disclosed in the literature of the said Korean patent application are included as a part of this specification.

Technical Field

The present application relates to a method of manufacturing an adhesive film.

A liquid crystal display (LCD) is a device that displays an image using liquid crystals, and has a low power consumption and is advantageous in various planes due to its advantages of being thin in plan.

Since the polarizing plate which is an optical member applied to the liquid crystal display device or the like has a structure in which films such as triacetyl cellulose, acryl, and cyclic olefins are usually laminated on one or both surfaces of the polarizer, the polarizing plate is adhered to the film and is a manufacturing process. To the process of making the LCD module, a film is required to protect the polarizer from external impact, friction and contamination.

Since the film is adhered to the polarizing plate during the process, it may be accompanied by optical inspection in the adhered state, so the transparency should be high. After the protective role, the film is removed and removed without unnecessary defects. Should be.

In particular, when a crater is present on the surface of the pressure-sensitive adhesive layer of the film, the crater of the film attached to the polarizing plate during the process is recognized as a defect of the polarizing plate itself, and there is a risk of a process interruption or the like occurring. There may be a risk of craters leaving defects in the polarizer upon removal of.

One object of the present application, to minimize the crater (crater) that can occur during the production of the adhesive film, to provide an adhesive film with improved optical properties.

The above and other objects of the present application can be achieved by the present application described in detail below.

In one example of the present application, the present application relates to a method for producing an adhesive film. The method of the present application can produce an adhesive film that can protect the polarizing plate from external impact, friction, and contamination from the manufacturing process of the polarizing plate to the process of making the LCD module.

The method of manufacturing the adhesive film may include applying an adhesive composition including an isocyanate compound, a metal compound, and an acrylic polymer on at least one surface of the base layer.

In one example, the isocyanate compound may be a bifunctional or polyfunctional compound. The isocyanate compound may react with the crosslinkable functional group of the acrylic polymer to implement a crosslinked structure.

The isocyanate compound is, for example, tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoborone diisocyanate, tetramethylxylene diisocyanate, naphthalene diisocyanate, triphenylmethanetriisocyanate or Isocyanate compounds, such as methylenebis (4-phenylmethane) triisocyanate, or the compound which made the said isocyanate compound react with a polyol can be used, As said polyol, trimethylol propane etc. can be used, for example. The pressure-sensitive adhesive composition may be used one kind or two or more isocyanate compounds in the above examples, but is not limited thereto.

The isocyanate compound may be included in an amount of 1 to 20 parts by weight based on 100 parts by weight of the acrylic polymer. The lower limit of the content of the isocyanate compound may be, for example, 2 parts by weight or more and 3 parts by weight or more, and the upper limit may be, for example, 15 parts by weight or less and 10 parts by weight or less. In this range, the degree of crosslinking of the pressure-sensitive adhesive composition can be appropriately adjusted, and through this, excellent physical properties such as cohesion, adhesion, and durability of the pressure-sensitive adhesive composition can be maintained.

In one example, the acrylic polymer may include a monomer having a crosslinkable functional group as a polymerized unit. In the present application, that the monomer is included as a polymerized unit may mean that the monomer forms a backbone, for example, a main chain or a side chain of the polymer or block through a polymerization reaction. The crosslinkable functional group is variously known in the adhesive production field, and is not particularly limited.

In one example, the monomer having a crosslinkable functional group may be a (meth) acrylate monomer having hydroxy, specifically 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate Hydroxyalkyl (meth) acrylates such as 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate or 8-hydroxyoctyl (meth) acrylate, or 2-hydroxyethylene Hydroxyalkylene glycol (meth) acrylates such as glycol (meth) acrylate or 2-hydroxypropylene glycol (meth) acrylate may be used, but is not limited thereto. By using the monomer which has the said crosslinkable functional group, adhesiveness which has suitable cohesion force and stress relaxation property, and has excellent durability reliability, workability, etc. can be formed.

In addition, the acrylic polymer may further include a (meth) acrylic acid ester monomer as a polymerized unit. As said (meth) acrylic acid ester monomer, the alkyl (meth) acrylate which has a C1-C20, C1-C16, C1-C12, C1-C8, or C1-C4 alkyl group is mentioned, for example. Can be used. The alkyl group in the above may be linear, branched or cyclic. Examples of such monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth ) Acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, n-octyl (meth) acrylate, iso Bornyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate and the like.

In one example, a metal compound may be included in the pressure-sensitive adhesive composition. The metal compound may be used as a catalyst for controlling the reaction rate of the pressure-sensitive adhesive composition, it may promote a crosslinking reaction to impart an appropriate cohesive force. In particular, the urethane reaction which is a crosslinking reaction can be selectively promoted, and the urea reaction which is a side reaction can be suppressed.

[Urea reaction]

The urea reaction is a reaction that may occur when isocyanate reacts with water contained in air or a solvent, and because craters may occur in the pressure-sensitive adhesive layer due to carbon dioxide (CO ₂ ) gas generated in the urea reaction process, the urea reaction may be suppressed. Crater generation can be suppressed.

The metal compound may include at least one metal of iron (Fe), zinc (Zn), zirconium (Zr), tin (Sn), and bismuth (Bi), and may preferably include iron (Fe). . In the case of aluminum (Al), which has been mainly used in the past, there is a problem in that the hardening promoting effect is small, the generation of craters cannot be suppressed, and the peeling force increases. On the other hand, by including the metal, the urea reaction can be effectively suppressed while maintaining the proper peeling force, thereby suppressing crater generation, and even if the crater is formed, only a very small size, for example, a crater with a diameter of 500 μm or less can be formed. Can be.

In one example, the metal compound may include a diketonate or a carboxylate as a ligand, preferably a diketonate as a ligand. The metal compound may exist in the form of a complex compound in which the at least one metal and the ligand are combined. By including the ligand, the urea reaction can be effectively suppressed to suppress crater generation, and even if craters are formed, only craters having a very small size, for example, a diameter of 500 μm or less can be formed.

In one example, the metal compound may be included in an amount of 0.01 to 0.5 parts by weight based on 100 parts by weight of the acrylic polymer. The lower limit of the content of the metal compound may be, for example, 0.03 parts by weight or more and 0.05 parts by weight or more, and the upper limit may be, for example, 0.4 parts by weight or less and 0.3 parts by weight or less. Within this range, the reaction rate of the pressure-sensitive adhesive composition can be appropriately controlled, and appropriate adhesion and durability can be imparted.

In the present application, the method of applying the pressure-sensitive adhesive composition on the base layer is not particularly limited, and for example, may be applied to the base layer by conventional means such as a bar coater.

In addition, the manufacturing method of the pressure-sensitive adhesive film, after the application of the pressure-sensitive adhesive composition may include the step of forming an adhesive layer by drying. The solvent or water included in the pressure-sensitive adhesive composition may be evaporated through the drying, and the drying temperature is not particularly limited, and may be appropriately adjusted according to the component and content of the solvent used.

In one example, the drying temperature may be at a temperature of 100 ° C or more or 110 ° C or more. The upper limit of the temperature is not particularly limited, but may be 150 ° C. or less. When drying in the above temperature range, the generation of craters can be suppressed by evaporation of moisture, the color index of the adhesive film can be lowered, transparency can be improved, and optical properties can be improved.

The drying time is not particularly limited, and in one example, the drying time may be in the range of 20 seconds to 120 seconds, 40 seconds to 100 seconds, or 50 seconds to 80 seconds.

The thickness of the pressure-sensitive adhesive layer formed is not particularly limited, and may be, for example, 6 μm to 100 μm, and in another example, 8 μm or more, 10 μm or more, or 15 μm or more, 90 μm or less, 70 It can be formed in a thickness range of less than or equal to 60 µm, less than or equal to 60 µm, or less than or equal to 50 µm. If the thickness of the pressure-sensitive adhesive layer is out of the above-described range, the formation of a uniform pressure-sensitive adhesive layer becomes difficult and there is a fear that the physical properties become uneven.

The base layer may be used without limitation the general transparency film in the art, for example, polyester film, such as polyethylene terephthalate or polybutylene terephthalate, polytetrafluoroethylene film, polyethylene film, polypropylene film, poly And plastic films such as butene films, polybutadiene films, vinyl chloride copolymer films or polyimide films. Such a base material layer may consist of a single layer of the said film, two or more layers may be laminated | stacked, and may further contain functional layers, such as an antifouling layer or an antistatic layer, in some cases. In the present invention, it is also possible to perform a surface treatment such as primer treatment on one side or both sides of the base layer from the viewpoint of improving the adhesion of the base layer.

The thickness of the base layer is not particularly limited as appropriately selected depending on the application, for example, may be 5 ㎛ to 500 ㎛, in another example, may be 10 ㎛ or more, 20 ㎛ or more, or 30 ㎛ or more , 400 μm or less, 300 μm or less, 200 μm or less, or 100 μm or less.

In one example, the pressure-sensitive adhesive composition may further include a curing retardant. The curing retardant is β-ketoester such as methyl acetoacetic acid, acetoacetate acetate, acetoacetate acetate, acetoacetate acetate, acetoacetate lauryl, acetoacetate stearyl, or acetylacetone, 2,4-hexanedione, One or more of β-diketones such as benzoyl acetone may be included.

The pressure-sensitive adhesive composition of the present application may further contain appropriate additives such as silane coupling agents, antioxidants, surfactants, curing accelerators, plasticizers, fillers, processing aids, and anti-aging agents, as appropriate. These can be used individually or in combination of 2 or more types.

In one example, the manufacturing method of the pressure-sensitive adhesive film may further include a step of laminating a release film after the drying step. The release film may be a film to which a release material is applied to prevent the adhesive from sticking. The type of release material is not particularly limited, but for example, a silicone release agent, a fluorine coating, a polyethylene coating, or the like may be used.

In one example, the method of manufacturing the pressure-sensitive adhesive film may further include a step of curing after lamination of the release film. The curing method is not particularly limited, and may be thermosetting or photocuring, and in one example, the curing may be performed at a temperature of 30 ℃ to 60 ℃. In addition, the curing time may be made for 24 hours to 72 hours. When the curing temperature is out of range, the release of the laminated release film may occur.

According to another example of the present application, in the pressure-sensitive adhesive film comprising a pressure-sensitive adhesive layer of the base material layer and the pressure-sensitive adhesive composition comprising an isocyanate compound, a metal compound, and an acrylic polymer, there are five craters of the pressure-sensitive adhesive layer. It may be a manufacturing method of the pressure-sensitive adhesive film is formed to be less than / m ² .

In one example, the crater may have a diameter of 500 μm or less, 400 μm or less, or 300 μm or less. The lower limit of the diameter is not particularly limited and may be, for example, 10 μm or more in diameter. The diameter of the crater may be measured in the two-dimensional shape of the pressure-sensitive adhesive layer viewed from above, and when the two-dimensional shape of the crater is not circular, the diameter may mean the length of the largest measurement.

In another example, the depth of the crater is measured to be less than the thickness of the pressure-sensitive adhesive layer, it may be less than 5㎛ or less than 3㎛. The lower limit of the depth is not particularly limited and may be 0.1 μm or more in depth. The depth of the crater may mean a length measured to be the largest of the depths formed by the crater, the deeper the thickness of the pressure-sensitive adhesive layer can be.

When the crater formed on the pressure-sensitive adhesive layer satisfies the number and size, the pressure-sensitive adhesive film excellent in durability and workability may be manufactured.

According to another example related to the present application, an optical film; And it may be an optical laminate comprising an adhesive film prepared according to claim 1 formed on one side or both sides of the optical film.

According to the manufacturing method of the pressure-sensitive adhesive film of the present application, the color index of the pressure-sensitive adhesive film is low, high transparency, the generation of craters can be minimized to provide an adhesive film excellent in durability and workability.

Hereinafter, the present application will be described in detail through examples. However, the protection scope of the present application is not limited by the examples described below.

Property measurement method

Experimental Example  1: Crater occurrence rating

In the following Examples 1 to 6 and Comparative Examples 1 to 4 the adhesive film was measured by the number of craters generated by a foreign material inspection. As a result of the measurement, there are X cases where craters with a diameter of 500 μm or more and a depth of 7 μm or more occur. C was evaluated in 10 cases, and more than 10 cases were evaluated as D. The results are shown in Table 2.

Experimental Example  2: Color index  evaluation

The color index of the pressure-sensitive adhesive film prepared in Examples 1 to 6 and Comparative Examples 1 to 4 was measured using a colorimeter (COH-400). The results are shown in Table 2, and the higher the value, the higher the yellowness, indicating the lower transparency.

Example  One

(1) Preparation of Pressure-Sensitive Adhesive Composition

2-ethylhexyl acrylate (2-ethylhexyl acrylate) and 2-hydroxyethyl acrylate (2-hydroxylethyl acrylate) were prepared in an acrylic polymer solution having a solid content of about 40% by copolymerization at a weight ratio of 95: 5. Ethyl acetate was used as the solvent.

And an iron compound (Fe (III) Acetylacetonete) having 5 parts by weight of an isocyanate compound (HDI trimer, product name: DR750HD), 7.5 parts by weight of acetylacetone, and diketonate as a ligand, based on 100 parts by weight of the acrylic polymer solution. The pressure-sensitive adhesive composition was prepared by uniformly blending 0.05 parts by weight.

(2) Preparation of adhesive film

The prepared pressure-sensitive adhesive composition is bar-coated on one surface of PET (poly (ethylene terephthalate)), and dried at 120 ° C. for 1 minute. Immediately after drying, the release film was laminated, and cured at 40 ° C. for 48 hours to prepare an adhesive film (1m × 100m) including an adhesive layer having a thickness of 15 μm.

Example  2 to 6 and Comparative example  1 to 5

(1) Preparation of Pressure-Sensitive Adhesive Composition

A pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except for changing the metal compound as shown in Table 1 below.

( 2) of adhesive film  Produce

The pressure-sensitive adhesive film was prepared in the same manner as in Example 1 except for changing the drying temperature of the prepared pressure-sensitive adhesive composition as shown in Table 1 below.

TABLE 1

 TABLE 2

Claims (15)

1. Applying an adhesive composition including an isocyanate compound, a metal compound, and an acrylic polymer on at least one surface of the base layer; And drying at a temperature of 100 ° C. or higher to form a pressure-sensitive adhesive layer.
2. The method of claim 1, wherein the metal compound comprises at least one of iron (Fe), zinc (Zn), zirconium (Zr), tin (Sn), and bismuth (Bi).
3. The method of claim 2, wherein the metal compound further comprises a diketonate or a carboxylate as a ligand.
4. The method of claim 3, wherein the metal compound comprises an iron (Fe) metal and a diketonate ligand.
5. The method of claim 1, wherein the acrylic polymer comprises a (meth) acrylate monomer having a hydroxyl group as a polymerized unit.
6. The method of claim 1, wherein the isocyanate compound is a bifunctional or polyfunctional compound.
7. The method of claim 1, wherein the base layer comprises a polyester film, polytetrafluoroethylene film, polyethylene film, polypropylene film, polybutene film, polybutadiene film, vinyl chloride copolymer film or polyimide film Method of producing an adhesive film.
8. The method of claim 1, wherein the pressure-sensitive adhesive composition comprises 0.01 to 0.5 parts by weight of a metal compound and 1 to 20 parts by weight of an isocyanate compound relative to 100 parts by weight of the acrylic polymer.
9. The method of claim 1, wherein the pressure-sensitive adhesive composition further comprises a curing retardant.
10. 10. The method according to claim 9, wherein the curing agent is selected from acetoacetic acid methyl, acetoacetate acetate, acetoacetate acetate, acetoacetate acetate, acetolauryl acetate, acetoacetate acetate, acetylacetone, 2,4-hexanedione or benzoylacetone. Method of producing one or more adhesive films.
11. The method of claim 1, further comprising laminating a release film on the pressure-sensitive adhesive layer after the drying step.
12. The method of claim 11, further comprising the step of curing in the temperature range of 30 ℃ to 60 ℃.
13. In the pressure-sensitive adhesive film prepared by the method of claim 1, wherein the pressure-sensitive adhesive layer is formed so that the crater (crater) is present in 5 / m ² or less.
14. The method of claim 13, wherein the crater has a diameter of 500 μm or less.
15. Optical film; And an adhesive film prepared according to claim 1 formed on one or both surfaces of the optical film.