KR19990081494A - Polyester release film coated with silicone resin and method for producing same - Google Patents

Abstract

The present invention relates to a polyester release film having excellent release properties and easy handling and winding process, and a method of manufacturing the same, and more particularly, to the surface roughness and silicone coating layer of a polyester base film in a polyester release film coated with a silicone resin. It is characterized in that the static friction coefficient of the silicon coating film for the base film to adjust the thickness of 0.15 or more.

Description

Polyester release film coated with silicone resin and method for producing same

The present invention relates to a polyester release film having excellent release properties and easy handling and winding process, and a method of manufacturing the same, and more particularly, to the surface roughness and silicone coating layer of a polyester base film in a polyester release film coated with a silicone resin. It is characterized in that the static friction coefficient of the silicon coating film for the base film to adjust the thickness of 0.15 or more.

Polyester films have good electrical, mechanical, thermal and chemical resistance. In particular, polyethylene terephthalate has excellent physical properties over a wide temperature range from low temperature to high temperature, excellent chemical resistance, good mechanical strength, surface properties and thickness uniformity, and excellent application to various applications and process conditions. It is widely used for industrial, medical, magnetic tape, condenser, photo film, label, etc., and the demand is increasing day by day to meet the trend of high speed and automation.

The general manufacturing process of a polyester film is as follows. A polyester resin blended with appropriate additives such as inorganic particles is cast into a highly polished drum through a melt extrusion process to form a sheet, and the molded sheet is a suitable temperature between the secondary transition temperature and the primary transition temperature of the polyester resin. Uniaxial or biaxial stretching is carried out while heating to cause orientation crystallization between polyester molecules. At this time, the biaxial stretching method may be first stretched in one direction, and then stretched in a right angle direction in this direction or simultaneously in both perpendicular directions. The uniaxial or biaxially stretched polyester film is heat-treated at a high temperature above the stretching temperature to produce a product. Thus prepared film has excellent physical properties of dimensional stability and high tensile strength over a wide temperature range.

On the other hand, as a main use of a mold release material, industrial uses, such as an adhesive tape, a label, medical use, casting, etc. are mentioned. In particular, the silicone-coated polyester release film is mainly used for high-quality applications requiring a beautiful appearance, high strength, high transparency, chemical resistance.

In general, a method of coating on a polyester film is divided into two types. One method is the general method known as "off-line coating", which is carried out stretching and heat setting, followed by coating after the production of the polyester film is completed. Another method, known as "in-line coating," is a method of coating a polyester film before it is finished stretching and heat setting during the manufacturing process of the polyester film. Drying of the coating film through the fixing process is not only an economically advantageous method, but also has a merit of obtaining a high quality coating film because the coating film is formed at a high temperature.

In general, the silicone resin has a weak adhesive strength with a plastic film and a low self-curing density, and thus has poor wear resistance and solvent resistance.

In order to improve the disadvantages of the silicone, a method of adding an organic modified silane as a coupling agent to a solvent-type silicone which is most widely used for release coating of plastic films has been used. As a representative example, Patent Publication No. 96-17750 discloses an amino silane system. Coupling agent, such as vinyl silane, epoxy silane, alkyl silane, methacryloxy silane and isocyanato silane, is added to the solvent-type addition-reaction type silicone and coated on the film. It describes that not only the adhesive force but also the degree of curing of the silicone layer itself can be increased, and it can be used for applications requiring strong solvent resistance such as pharmaceuticals.

Conventionally, solvent-type silicone has been used in the production of silicone coated polyester release film. This is because the use of solvent-type silicone is most advantageous in terms of curing of the silicone coating film and ease of application. However, in the case of using a solvent-type silicon, although a high quality coating film is obtained, there is a problem that not only increases the manufacturing cost by using the organic solvent during the coating but also causes environmental pollution due to the air emissions of the organic solvent.

A method of using a solvent-free silicone or an emulsion-type aqueous silicone as a material to replace the solvent-type silicone having such a problem has been attempted.

Solvent-free silicone is classified into UV curing type and thermosetting type depending on the curing method. However, the coating solution containing the solvent-free silicone is not applicable to the existing equipment used for coating the solvent-type silicone due to its high viscosity and is not thinly coated. Therefore, the method of using the solvent-free silicone is disadvantageous in terms of manufacturing cost. There is this.

As a method of using an aqueous silicone in the form of an emulsion, Canadian Patent No. 1,120,176 discloses a hydrogen atom bound to 20 to 50% by weight of silicon atoms based on diorganopolysiloxanes containing vinyl groups at the molecular chain ends, and diorganopolysiloxanes. An aqueous silicone system for producing a release film comprising at least three or more organopolysiloxanes and a catalytic amount of platinum catalyst is disclosed.

U.S. Pat. It is described as. However, the present invention also has a disadvantage in that the solvent resistance is not sufficient and the release property is not good for the pressure-sensitive adhesive having a strong solvent power, and the wear resistance is also insufficient.

U.S. Patent No. 4,851,166 discloses a method for producing a release film by in-line coating using a solventless silicone, in which an amine volatile inhibitor is added to prevent cracking of the silicone coating film by stretching. It is disclosed that it can. However, this method still has the disadvantages of the solvent-free silicone described above.

The aforementioned methods of using solvent-type silicones, solvent-free silicones and emulsion-type aqueous silicones relate to addition-curable silicones in which the silicone coating composition is all cured by hydrosilylation reactions. Type silicone may be used in the manufacture of the release film, but in this case, there are disadvantages in terms of curing rate and degree of curing compared to the case of using additional curing silicone.

Conventionally manufactured silicone-coated polyester release film has a very low surface friction coefficient due to the surface of the silicon is very poor in handling, and there is a high possibility of failure when applying the winding process and the product to the post process. In particular, when the release film is made of a silicone release tape by microslitting, a silicone coating film having a low surface friction coefficient is very difficult to work with and has a high possibility of defects.

Accordingly, it is an object of the present invention to provide a silicone-coated polyester release film and a method for producing the same, which have excellent release properties and are easy to handle and wind.

According to the above object in the present invention is characterized in that the friction coefficient of the release film in the range of 0.15 or more by adjusting the surface roughness of the polyester base film and the thickness of the silicone coating layer in the silicone-coated polyester release film.

The polyester film used as the substrate in the present invention is a uniaxial or biaxially stretched, extruded, molded, polyester resin containing an inorganic lubricant according to a conventional method. Here, polyester polycondenses the acid component which has aromatic dicarboxylic acid as a main component, and the glycol component which has alkylene glycol as a main component. Specific examples of the aromatic dicarboxylic acid include dimethyl terephthalate, terephthalate acid, isophthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyldicarboxylic acid, di Phenyl ether dicarboxylic acid, anthracenedicarboxylic acid, α, β-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid, and the like. Among these, dimethyl terephthalate and terephthalic acid may be used. Particularly preferred. Specific examples of the alkylene glycol may include ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, hexylene glycol, and the like. Of these, ethylene glycol is particularly preferable. The polyester of the present invention is a homopolyester of 60% by weight or more of polyethylene terephthalate and may be copolymerized within 40% by weight. Specific examples of the copolymerization components include diol compounds such as diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, p-xylene glycol, 1,4-cyclohexanedimethanol, 5-sodium sulforezocin, adipic acid, 5 -Polyfunctional carboxylic acid components, such as dicarboxylic acid components, such as sodium sulfoisophthalic acid, trimellitic acid, a pyromellitic acid, etc. are mentioned.

In addition, as the inorganic lubricant added to the polyester resin, inorganic lubricants commonly used in the production of polyester films such as calcium carbonate, silica, and kaolin can be used, and the type of lubricant is not limited.

In the present invention, the silicone coating layer may be prepared by coating a silicone resin composition on a polyester base film and then drying. The release coating silicones used here include solvent-type silicones such as SS4164A system from GE Silicone, LS203 system from Dow Corning, Q2-7610 system from Dow Corning, SL6100 system from General Electric, etc. The same solvent type silicone, or aqueous emulsion type silicone such as General Electric's SM3000 system, Dow Corning's Syloff 7900 system, and the like can be used, and the state of the silicon is not limited. In addition, condensation polymerization type or addition polymerization type may be used depending on the curing type of silicon, and addition polymerization type silicon is preferable.

As a method of coating the silicone resin composition on a polyester film substrate, a conventional coating method may be used, and typical examples of the coating method may include roll coating, spray coating, gravure coating, reverse gravure coating, mayer bar coating, die coating, and the like. It may include, but is not limited to.

In addition, the silicone resin composition may be 'in-line coating' or 'off-line coating' depending on when it is coated, and in-line coating is preferable. In the case of in-line coating, since the curing reaction of the silicone composition proceeds in the heat setting process of the polyester film, the curability of the silicone coating film is excellent, and the physical properties of the coating film are improved by the orientation according to the stretching.

The film coated with the silicone resin composition is dried at 100 to 200 ° C. for 10 seconds to 2 minutes.

In the present invention, the static friction coefficient of the silicon coating film for the base film is preferably adjusted to the range of less than 0.15 to 1.0. As a method of controlling the static friction coefficient of the silicon coating film for the base film, there is a method of adjusting the thickness of the silicon coating layer and a method of controlling the roughness of the base film. In order to maintain an appropriate surface friction coefficient, the silicon coating amount should be adjusted according to the roughness of the base film. In the case of the base film having a surface roughness (Rz) in the range of 120 to 230 nm, the thickness of the silicon coating layer is appropriate in the range of 70 to 200 nm, and the silicon coating layer when the roughness (Rz) of the base film is 230 to 500 nm. The thickness of is preferably in the range of 150 to 500 nm. The static friction coefficient of the silicone coating film relative to the base film of the silicone release film thus adjusted is in the range of 0.15 to less than 1.0, preferably in the range of 0.20 to less than 1.0, and the workability in handling and post workability is good. When the roughness Rz of a base film is 120 nm or less, a friction coefficient is too high, and the ease of handling of a film and workability in a post process are bad.

The release film of the present invention may be made of a release film tape of a reel type by microslitting to a width of 100 mm or less.

Hereinafter, the present invention will be described in detail by way of examples, but the content of the present invention is not limited thereto.

Evaluation of the characteristics of the silicon coating film produced in the embodiment of the present invention was used the following method.

1) Release peel force

A measurement sample made by adhering a 25 nm wide adhesive tape 31B (Nitto) to a silicon coated surface with a force of 2 kg was loaded with a pressure of 20 g / cm 2 for 20 hours in an oven at 70 ° C., and then about 15 minutes at room temperature. The force applied was measured while leaving to stand at a speed of 300 mm / minute and an angle of 180 °.

2) static friction coefficient

It was measured according to ASTM D1894.

3) Surface roughness (十 点 平均 組 度: Rz)

Measure the cross-sectional roughness of the base film using SE30D (Kosaka Lab, Japan) under the condition that the needle diameter is 2 µm and cut-off 0.08 mm, and the five peaks within the sample measurement length of the cross-sectional roughness curve are measured. Surface roughness was calculated according to the following equation from the sum of peak values and the sum of the lowest five valley values.

Examples 1-4 and Comparative Examples 1-3

The polyethylene terephthalate resin was extruded, molded and stretched to prepare a polyester film having a thickness of 12 μm and having a surface roughness of Table 1 below. Doe Corning's Syl-off 7900 and 7922 (40% solids) and pure water were coated on the polyester film according to the Mayer bar coating method (size: # 3) and the pure water was blended according to the composition shown in Table 1 below. After drying in an oven for 2 minutes, the release films of Examples 1 to 4 and Comparative Examples 1 to 3 were prepared.

The release films were manufactured using Nitto's 31B as an adhesive tape to measure the release peeling force and the static friction coefficient. The results are shown in Table 1 below.

Surface Roughness of the Base Film (Rz) (nm) Composition (% by weight) Silicon Coating Layer Thickness (nm) Release peel force (g / in) Static friction coefficient Dow Corning Syl-off 7900 Dow Corning Syl-off 7922 Pure weight Comparative Example 1 300 7.2 0.8 92 90 7.5 0.11 Example 1 300 13.5 1.5 85 190 7.2 0.36 Example 2 300 22.5 2.5 75 280 7.3 0.67 Example 3 190 7.2 0.8 92 90 7.9 0.63 Example 4 190 13.5 1.5 85 190 7.7 0.81 Comparative Example 2 110 7.2 0.8 92 90 8.0 1 or more Comparative Example 3 110 4.5 0.5 95 50 17.8 1 or more

As shown in Table 1, the release films of Examples 1, 2, and 3 have excellent release properties and static friction coefficients, whereas the release films of Comparative Examples 2 and 3 having a surface roughness (Rz) of the base film of 120 nm or less Not only is the friction coefficient of the surface too high, but also a blocking phenomenon occurs between the films, rather, defects are more likely to occur in the manufacturing process, and in particular, the release film of Comparative Example 3 has a low thickness of the silicone coating layer, thereby reducing the release properties. In addition, when the surface roughness (Rz) of the base film is 230nm or more, the application amount of the silicon film should be high. In the case of Comparative Example 1, in which the application amount is small, the friction coefficient between the inner and outer surfaces of the film is difficult to handle the release film.

The silicone-coated polyester release film according to the present invention is excellent in mold release by adjusting the coefficient of friction by adjusting the surface roughness of the base film and the thickness of the silicone coating layer, and is easy to handle and wind up.

Claims (6)

A release film coated with silicone, wherein the coefficient of static friction of the silicone coating film relative to the polyester base film is in the range of 0.15 or more. The method of claim 1, Release film, characterized in that the surface roughness of the polyester base film ranges from 120 to 230nm and the thickness of the silicone coating layer is in the range of 70 to 200nm. The method of claim 1, Release film, characterized in that the surface roughness of the polyester base film in the range of 230 to 500nm and the thickness of the silicon coating layer is in the range of 150 to 5000nm. In the method of producing a polyester film by extruding, molding and stretching a polyester resin, and coating a silicone coating composition on the obtained film to produce a silicone release polyester release film, the surface roughness of the polyester base film and Method of manufacturing a release film, characterized in that the static friction coefficient of the silicon coating film relative to the base film to the range of 0.15 or more by adjusting the silicon coating thickness. The method of claim 4, wherein The surface roughness of the polyester base film ranges from 120 to 230nm and the thickness of the silicon coating layer is characterized in that the range of 70 to 200nm. The method of claim 4, wherein The surface roughness of the polyester base film ranges from 230 to 500 nm and the thickness of the silicon coating layer is characterized in that the range of 150 to 5000 nm.