KR20180086379A - Polyester film having improved laminating intensity for optical and general industry - Google Patents

Abstract

Provided is a polyester film for optical and general industries with improved lamination intensity by adjusting transmittance of an ultraviolet region specifically. The polyester film for optical and general industries uses, as a base material, a biaxially stretched polyester film having thickness of 100-250 μm while not containing inorganic particles, and a primer layer is formed as a polymeric adhesive layer on one or both sides of the base material.

Description

[0001] The present invention relates to an optical and general industrial polyester film having improved lint strength,

The present invention relates to optical and general industrial polyester films with improved lint strength. More particularly, the present invention relates to an optical and general industrial polyester film capable of adjusting ultraviolet transmittance of a film to satisfy optimum lint strength and ultimate physical properties.

Generally, a polyester film has a stable chemical structure and thus has high mechanical strength and excellent properties in terms of physical properties such as heat resistance, durability and chemical resistance. For example, polyethylene terephthalate is excellent in stability of physical properties over a wide temperature range from low temperature to high temperature, excellent in chemical resistance, good in mechanical strength, surface characteristics, thickness uniformity, and has excellent adaptability to various process conditions , Industrial use, medical use, packaging, and the like.

In recent years, such a polyester film has been widely used as an optical substrate film. The optical film is a plastic film used for optical use. It is a concept including a diffusion film, a diffusion protective film, a prism sheet, etc., and the optical base film is highly crystalline oriented and is used for a diffusion film, a prism sheet, a paint, Is not sufficient. In order to improve the adhesion of such a polyester film, a flame treatment, that is, a corona treatment or a plasma treatment may be applied to the surface of the polyester film. Such a surface treatment method has a problem in that the adhesive strength remarkably decreases with time.

In addition to the physical treatment of the film surface, various techniques for improving the adhesion of the polyester film by a film coating method using a specific composition have been proposed.

Korean Patent Registration No. 10-0718920 discloses a polyester film produced by applying a water-dispersed polyurethane resin to the polyester film surface in an amount of 12 to 20 wt% and biaxially stretching the polyester film. However, inorganic or organic particles are included in the coating composition There is a problem that a blocking phenomenon occurs when the film is wound.

In addition, Korean Patent Publication No. 10-1124581 discloses an optical adhesive polyester film having a structure in which a primer layer including a curing catalyst and a curing agent is formed on a heat-reactive water-soluble urethane resin. However, There is a problem that an excessive amount of urethane resin is contained in order to prevent the adhesive strength from lowering under the condition that the application of the coating liquid is uneven and unevenness may occur in the coating layer.

In addition, Korean Patent Laid-Open No. 10-2010-0081568 discloses a primer layer comprising a primer layer containing a thermosensitive water-soluble urethane resin, a thermosensitive resin, a tin catalyst, silica particles, an anionic surfactant, Discloses an adhesive film. However, there is a problem in that it is focused on improving the surface hardness. In the case of a heat-responsive resin, an excessive amount of a thermosetting agent is used, and the coating layer is hardened.

In order to solve such a problem, Korean Patent Laid-Open Publication No. 10-2012-0038650 discloses a biaxially stretched polyester film based on a biaxially stretched polyester film having a thickness of 100 to 250 탆 without containing inorganic particles, Discloses an optical film in which a primer layer is formed on an end face or both sides of a base material as an adhesive layer. The polymer primer layer is formed by using a polyurethane resin having a branched monomer as a constituent component and silica particles having an average particle diameter of 80 to 140 nm Discloses a multi-purpose biaxially stretched polyester film having improved luminance and transparency formed by including alumina-silica composite oxide particles. This patent discloses that the double-sided polyurethane primer layer used in the biaxially stretched polyester film is excellent in adhesion not only with the base material but also with the adhesion properties required in the post-processing step, Therefore, there is an effect of excellent optical characteristics.

However, it is an object of the present invention to provide an optical or general industrial polyester film having improved lint strength by adjusting the transmittance of an ultraviolet region band, in order to solve the conventional problems in a manner different from existing patents.

The optical and general industrial polyester film of the present invention is a biaxially stretched polyester film having a thickness of 100 to 250 占 퐉 without containing inorganic particles and the polymer is applied on both sides or both sides of the base material as a primer layer .

In the present invention, the primer layer uses a polyurethane resin having a branched monomer as a constituent, and silica is 7 to 10 wt% in the case of an average particle diameter of 50 nm and 4 to 8 in the case of 80 to 100 nm in consideration of the transmittance. wt%, and 4 wt% or less in the case of 140 nm.

The optical and general industrial polyester films according to the present invention have an effect of adjusting the transmittance of the film for a product requiring film laminating and adjusting the degree of curing of the UV adhesive during the laminating process to satisfy the lint strength and the final properties.

Hereinafter, the present invention will be described in detail.

The present invention relates to a laminate (polyester molded article) including a product in which laminating of a polyester film is required in an optical or general industry, such as a polyester film, by adjusting the transmittance of the film in a range of 80 to 90% By adjusting the curing degree of the ultraviolet (UV) adhesive during the laminating process to 100 to 300 gf / in, the lint strength is improved from 100 to 300 gf / in, and the final physical properties such as luminance and interlaminar adhesion are satisfied.

The transmittance generally refers to the transmittance of a propagation field, but in the present invention, only the transmittance of a specific wavelength is referred to. For example, the photo-radical initiator used in ultraviolet (UV) tackifiers is subjected to photo-radical initiation at 300-400 nm and participates in the curing reaction. The transmittance of a polyester film laminated with an ultraviolet (UV) pressure-sensitive adhesive should be maintained at 92 to 94% in a wavelength range of 300 to 400 nm.

If the transmittance is lower or higher than the above-mentioned transmittance, the strength of the laminate will be too low or too low to easily peel off or adversely affect the final properties.

The biaxially stretched polyester film of the present invention can be produced by using a biaxially stretched polyester film having a thickness of 100 to 250 탆 as a substrate without containing inorganic particles and forming a primer layer as an adhesive layer on the cross- It is an optical film.

Examples of the polyester-based resin constituting the film in the present invention include linear saturated polyesters synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Specific examples of the polyesters usable in the present invention include polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate and polybutylene terephthalate. From the viewpoints of accessibility, economy and effect, polyethylene terephthalate, polyethylene Naphthalate and the like are preferable. As the material of the film, a mixture of these copolymers or a mixture thereof with other resins in a small proportion can also be used as long as the effects of the present invention are not impaired.

The polyester film of the present invention can be formed by orientation crystallization by vertical and horizontal biaxial stretching on a melt extruded film as described above and crystallization by heat treatment.

The thickness of the polyester film in the present invention is not particularly suggested, but may be appropriately selected depending on the intended use of the film. It is generally preferable to use 5 to 500 mu m.

On the other hand, the polymer primer layer uses a polyurethane resin having a branched monomer as a constituent, and the thickness of the primer layer is preferably in the range of about 0.01 탆 to 0.5 탆. However, if the thickness is less than 0.01 탆, uniform application is difficult, The coating unevenness tends to occur. On the contrary, when the thickness is more than 0.5 mu m, the films tend to stick to each other, or the light transmittance of the entire film may deteriorate.

According to the present invention, a primer layer can be formed on one side or both sides of a polyester base film using a polyurethane resin coating composition. The polyurethane resin coating composition used in the present invention is a composition comprising 10 to 75% by weight of a linear polymer having two terminal groups on one or both sides and 25 to 90% by weight of a branched polymer having three or more terminal groups And a water-dispersible polyurethane resin having an average molecular weight of 10,000 to 20,000.

Here, the water-dispersible polyurethane resin is prepared by reacting 39 to 45% by weight of polyol, 0.3 to 1.2% by weight of trimethylolpropane and 50 to 57% by weight of isocyanate compound to prepare a prepolymer having isocyanate as an end group, To 4% by weight of the isocyanate and blocking the ionic group at the terminal of the isocyanate.

The primer layer may be coated by in-line coating applied to the surface during the stretching process of the polyester film, or by offline coating after the film is formed. It is also possible to use both of them in parallel. Preferably, in-line coating is performed simultaneously with the film formation, so that the production cost is reduced, and the thickness of the coating layer can be changed by the extension ratio.

In consideration of the transmittance, the silica is formed to include 7 to 10 wt% in the case of an average particle diameter of 50 nm, 4 to 8 wt% in the case of 80 to 100 nm, and 4 wt% or less in the case of 140 nm .

Hereinafter, the present invention will be described in more detail with reference to examples.

Example  One

Silica particle size Silica content UV transmittance Lint strength Luminance Example 1 50nm
80nm
140 nm 7wt%
4wt%
1 wt% 92.5% 270 gf / in 100% Example 2 50nm
90 nm
140 nm 9wt%
7wt%
2wt% 92.0% 285 gf / in 99.5% Example 3 50nm
10 nm
140 nm 10wt%
8wt%
3% 91.3% 300 gf / in 96% Comparative Example 1 50 nm One % 83.2% 145 gf / in 90% Comparative Example 2 50 nm 2 % 83.0% 140 gf / in 92% Comparative Example 3 50 nm 7% 82.3% 200 gf / in 90.3% Comparative Example 4 80 nm 5% 82.6% 230 gf / in 90.4%

A biaxially stretched polyester film having a thickness of 100 탆 which does not contain inorganic particles is used as a base material and a polymer is used as an adhesive layer on the end face of the base material and a primer layer is formed by using a polyurethane resin having a branched monomer as a constituent component And was formed as silica as shown in Table 1 above.

As a result, the physical properties required in the laminate of the polyester film were obtained as shown in Table 1.

Example  2 to 3

The procedure of Example 1 was followed and silica was included as shown in Table 1. The results are shown in Table 1.

Comparative Example  1 to 4

The procedure of Example 1 was followed and silica was included as shown in Table 1. The results are shown in Table 1.

According to Table 1, the present invention relates to a laminate (polyester molded article) including a product in which a laminate of a polyester film is required in an optical or general industry, for example, a polyester film, and has a film transmittance of 80 to 90% It was possible to adjust the curing degree of ultraviolet (UV) adhesive during laminating process from 100 to 300 gf / in and to improve lint strength from 100 to 300 gf / in. Results were obtained.

It was also found that the polyester film laminated with an ultraviolet (UV) pressure-sensitive adhesive maintains a transmittance of about 92 to 94% at a wavelength range of 300 to 400 nm.

Although the preferred embodiments of the present invention have been described in detail to some extent, it is natural that various modifications can be made to them. It is therefore to be understood that the invention may be practiced otherwise than as specifically described herein without departing from the scope and spirit of the invention.

Claims (2)

Wherein a biaxially stretched polyester film having a thickness of 100 to 250 占 퐉 is used as a base material without containing inorganic particles and a primer layer is formed as an adhesive layer on the end face or both sides of the base material, And general industrial polyester film. The primer layer according to claim 1, wherein the primer layer comprises a polyurethane resin having a branched monomer as a constituent, wherein the silica has a transmittance of 7 to 10 wt% for an average particle diameter of 50 nm, 4 to 8 wt%, and in the case of 140 nm, 4 wt% or less.