KR19990069465A - Polyester film for adhesive tape - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a polyester film for an adhesive tape.

2. The technical problem to be solved by the invention

The present invention significantly improves ink adhesion by applying an aqueous dispersion containing a water-dispersible polyurethane resin as a main component to the surface of a polyester film, and exhibits excellent physical properties even under harsh environments of high temperature and high humidity. The purpose is to provide a polyester film.

3. Summary of Solution to Invention

The present invention for achieving the above object is "dicarboxylic acid component, glycol component, diisocyanate component and at least one side of the polyester film of 60% by weight or more of the main repeating unit made of ethylene terephthalate, A coating film comprising a water-dispersible polyurethane resin, a surfactant, and a slip agent prepared by copolymerizing a compound to be expressed is coated with a thickness of 0.001 to 1 μm polyester film for pressure-sensitive adhesive tape.

<Formula 1>

(In Formula 1, R represents an aliphatic hydrocarbon group having 1 to 12 carbon atoms, and n and m are each independently an integer of 1 to 5).

4. Important uses of the invention

This invention has the use as various adhesive tapes.

Description

Polyester film for adhesive tape

The present invention relates to a polyester film for pressure-sensitive adhesive tape, and more particularly to a polyester film for pressure-sensitive adhesive tape excellent in water resistance, solvent resistance and ink adhesion.

Widely used for general packaging, seam treatment, adhesive support, etc., adhesive tapes are roughly classified into single-sided adhesive tapes or double-sided adhesive tapes. In recent years, various special products for imparting heat resistance, cold resistance, and flame resistance have been introduced. .

As a base material used in the production of such an industrial adhesive tape, a film made of polyethylene terephthalate (hereinafter referred to as PET), oriented polypropylene (Oriented Poly propylene), paper, nonwoven fabric, or the like is generally used. As a film base material for application to high-quality applications, it is common to use a polyester film made of PET or the like in consideration of heat resistance and durability.

The polyester film, particularly PET film, has excellent dimensional stability in a wide temperature range compared to polyethylene and polypropylene film, which are polyolefin-based products, and is particularly used for packaging, porcelain, industrial, etc. due to its excellent thermal stability.

In the case of manufacturing the adhesive tape using the above-mentioned PET film, various colors and patterns are printed in consideration of the use of the final product, thereby pursuing differentiated functionalities between the products. For this purpose, before applying the adhesive to the film substrate, Printed the desired color and pattern with the general PET ink to achieve the desired color, but when the ink is directly used on the PET film substrate, the adhesion between the ink layer and the PET film is degraded and the ink layer is separated. have.

This phenomenon is because methyl ethyl ketone (MEK) or ethyl acetate, which is used as an organic solvent in the manufacture of the adhesive, does not completely volatilize during drying after the adhesive is applied, thereby reducing the adhesion between the ink and the PET film surface during the curing process. As a result, it is not possible to implement the color as expected, as well as a severe problem in the harsh environment of high temperature and high humidity has a serious problem that can not exhibit the original function as the adhesive tape.

In order to solve the above problems, there is a known method of pre-treatment such as coating and corona before the printing process or other processing process on PET film, but in the case of corona treatment, there is a limit in improving the adhesive strength with the ink layer, In the case of coating the resin on the resin, it has excellent physical properties such as adhesiveness, but it is inevitable that the trouble of the post-process, environmental problems due to the outflow of the solvent made of organic compounds, the problem of the working environment and the additional cost of increasing the manufacturing price are inevitable.

In this regard, U.S. Patent Nos. 4,486,483 and 4,544,200 disclose a composition comprising a non-toxic coating comprising a alkali metal salt of an unsaturated fatty acid and an alkali metal salt of an alkyl sulfate as a primer on the surface of the film to impart ink adhesion to the film. Although there is provided a method for producing a polyester film for pressure-sensitive adhesive improved, this is a problem that the solvent resistance is low and the adhesive strength in a high temperature and high humidity environment is lowered.

In particular, during the manufacture of the adhesive tape, an aging process is essential. In this case, the original physical properties must be maintained under extremely harsh conditions (65 ° C., 85% relative humidity, 72 hours), and The temperature should not be changed even when the temperature is high (120 ° C., 30 minutes) or low (5 ° C., 30 minutes), and the durability of the solvent after ink printing should be at least a certain level. In terms of physical properties, there is a problem that a desired result cannot be obtained.

As a technique for imparting excellent adhesion even in a harsh environment of high temperature and high humidity separately from the prior art, Japanese Unexamined Patent Publication No. 84-51424 attempts to improve water resistance by dissolving a coating liquid in an organic solvent. It is not possible to obtain desirable results in terms of the use of organic solvents, there is a risk of ignition when applied, odor is severe and has problems such as environmental damage.

The present invention is to solve the above problems of the prior art, the surface of the polyester film by applying an aqueous dispersion containing a water-dispersible polyurethane resin as a main component to pre-treatment, excellent solvent resistance and significantly improved ink adhesion and At the same time, the water resistance is also very good to exhibit excellent physical properties even in the harsh environment of high temperature and high humidity, and to provide a polyester film for pressure-sensitive adhesive tape that can prevent environmental pollution due to the use of organic solvents in the manufacturing.

The present invention for achieving the above object is a dicarboxylic acid component, a glycol component and a diisocyanate component and at least one side of the polyester film of 60% by weight or more of the main repeating unit made of ethylene terephthalate, It provides a polyester film for pressure-sensitive adhesive tapes, characterized in that the coating composition prepared by copolymerizing the compound represented by the present invention is coated with a thickness of 0.001 to 1μm coating composition comprising a water-dispersible polyurethane resin, a surfactant and a slip agent.

In Formula 1, R represents an aliphatic hydrocarbon group having 1 to 12 carbon atoms, and n and m are each independently an integer of 1 to 5.

The polyester used as the material of the base film in the present invention has an intrinsic viscosity of 0.4 to 0.9 dl / g, preferably 0.5 to 0.8 dl / g when measured at a concentration of 0.3 g per 25 ml of orthochlorophenol at 35 ° C. If the intrinsic viscosity is less than 0.4 dl / g, the breakage during stretching in the film manufacturing process is frequently caused and the productivity is greatly reduced. If the intrinsic viscosity is more than 0.9 dl / g, the melt viscosity is considerably increased. Therefore, productivity in the post process is greatly reduced due to difficulties in the manufacturing process, such as unstable extrusion process during the film forming process.

The polyester of the present invention as described above is obtained by polycondensing a polyhydric organic acid component and a polyhydric alcohol component. The organic acid is preferably a carboxylic acid, particularly an aromatic dicarboxylic acid, and the alcohol is preferably glycol, in particular alkylene glycol. desirable.

Specific examples of the aromatic dicarboxylic acid include dimethyl terephthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyldicarboxylic acid and diphenyl ether. Dicarboxylic acid, anthracenedicarboxylic acid or α, β-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid, of which dimethyl terephthalic acid or terephthalic acid is particularly preferred.

Specific examples of the alkylene glycol include ethylene glycol, methylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol and hexylene glycol, of which ethylene glycol is particularly preferable.

60% by weight or more of the polyester of the present invention is a homopolyester of polyethylene terephthalate and may be copolymerized with other copolymerization components within the remaining 40% by weight.

Such copolymerization components include diol compounds such as diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, p-xylene glycol, 1,4-cyclohexanedimethanol or sodium 5-sulforezosuccine, adipic acid, or Dicarboxylic acids such as sodium 5-sulfoisophthalic acid and the like or multifunctional carboxylic acids such as trimellitic acid, pyromellitic acid and the like.

In the polymerization process of the polyester prepared from such components, inorganic fillers such as calcium carbonate and other conventional additives may be added.

The water-dispersible polyurethane resin applied to the surface of the polyester film of the present invention as described above is prepared with an aqueous dispersion of 1 to 10% by weight, the coating liquid is 0.01 to 0.5% by weight of surfactant and 0.1 to 0.3% by weight It may contain% slip agent.

The surfactant is added for uniform application when the concentration is diluted to control the coating amount, and the slip agent is added to impart slip property to the water-dispersible polyurethane resin composition. In order to improve the coilability and handleability, a wax such as an inorganic filler of silica type, an organic filler containing a fluorine resin type, an acrylic type, or the like, or a polyethyl type wax can be used.

The water-dispersible polyurethane resin, which is a main component of the water-dispersible coating liquid used in the present invention, is a polyurethane component prepared by polymerizing a dicarboxylic acid component, a glycol component and a diisocyanate component by a conventional method, and a polyester containing OH group and COOH group. It is prepared by copolymerizing the components.

The dicarboxylic acid component used in the polymerization of the polyurethane component is aromatic di, such as terephthalic acid, isophthalic acid, 1,4-naphthalene dicarboxylic acid, 2,5-naphthalene dicarboxylic acid, 2,5-methyl terephthalic acid, dimethyl isophthalic acid and the like. Aromatic or aliphatic dicarboxylic acids such as carboxylic acid, 1,3-cyclopentane dicarboxylic acid, 1,2-cyclohexane dicarboxylic acid, 1,3-cyclohexane dicarboxylic acid, or 1,4-cyclohexane dicarboxylic acid. Aromatic dicarboxylic acids are particularly preferred.

Also useful as glycol components are aliphatic glycols having 2 to 8 carbon atoms and aliphatic glycols having 6 to 12 carbon atoms, for example ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neo Pentyl glycol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4 cyclohexanedimethanol, p-xylene glycol, diethylene glycol, triethylene glycol, etc. Polyether glycol, polyethylene glycol, polytetramethylene glycol, and the like may also be used.

Along with this, as the diisocyanate component, 5-isocyanate-1-isocyanatemethyl-1,3,3 as one of the compounds represented by 2,4-hexamethylene diisocyanate, 2,6-hexamethylene diisocyanate, and the following general formula (2) -Trimethyl cyclohexane and the like and derivatives thereof can be used, and among these, 5-isocyanate-1-isocyanatemethyl-1,3,3-trimethyl cyclohexane and derivatives thereof are more preferable.

In Formula 2, R 1, R 2, and R 3 independently represent an aliphatic hydrocarbon group having 1 to 12 carbon atoms.

Another component used in the water-dispersible polyurethane resin of the present invention is a polyester component includes the compounds represented by the formula (1).

That is, the water-dispersible polyurethane resin used in the present invention includes at least one dicarboxylic acid component such as dimethyl terephthalic acid, at least one glycol component such as ethylene glycol, and 5-isocyanate-1-isocyanatemethyl-1,3,3-trimethylcyclo It is a polyurethane resin copolymerized by the normal polymerization method by adding the compound of General formula (1) to the 1 or more types of diisocyanate components of General formula (2), such as hexane.

At this time, the compound of Formula 1 in the polyurethane resin is preferably 10 to 90% by weight, preferably composed of 70 to 80% by weight.

1 to 10% by weight of the polyurethane resin prepared in this way is dispersed in a polar solvent such as water to prepare an aqueous dispersion. Prepare an aqueous dispersion.

The aqueous dispersion also contains other additives known in the art, such as antistatic agents, wetting agents, pH adjusting agents, antioxidants, dyes, pigments and the like in an effective amount within a range that does not reduce the adhesion between the deposition layer and the base film. Can be added.

The method for producing the polyester film of the present invention is not particularly limited, and the polyester resin having an intrinsic viscosity of 0.4 to 0.9 dl is melt-extruded by a conventional method and electrostatically applied on a 20 to 30 ° C. cooling roll to form a sheet. Thereafter, the unstretched sheet is stretched 2 to 5 times, preferably 3 to 4 times in the longitudinal direction at 70 to 100 ° C., and then 2 to 5 times in the transverse direction at 100 to 120 ° C., preferably 3 to 4 times. Stretched 4 times, and then heat-setting the biaxially stretched sheet at 200 to 260 ° C, preferably 220 to 240 ° C to apply the water-dispersible polyurethane resin solution to the sheet surface and then dry it to obtain a biaxially stretched polyester. Prepare a film.

At this time, the water-dispersible coating liquid containing the water-dispersible polyurethane resin according to the present invention as a main component may be applied to at least one side of the unstretched polyester sheet or to at least one side of the stretched sheet on one side.

In addition, the biaxially stretched film is first prepared according to the above stretching process, and then the aqueous dispersion is applied to at least one side of the obtained film and dried to prepare the polyester film of the present invention. It is preferable to set it as 0.001-1 micrometer.

In the present invention, various coating methods known to the polyester film (gravure, roll, mayer bar, air knife, etc.) when the dispersion coating liquid is applied to the unstretched or uniaxially stretched polyester sheet or biaxially stretched polyester film. It can be applied through an offline method of applying and drying.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples.

<Example 1>

Dimethyl terephthalic acid and dimethyl isophthalic acid as the dicarboxylic acid component, ethylene glycol and diethylene glycol as the glycol component, and 5-isocyanate-1-isocyanatemethyl-1,3,3-trimethyl cyclohexane as the diisocyanate component The compound of 1a was copolymerized by a conventional polymerization method, and a water-dispersible polyurethane resin having a weight ratio of 75% by weight of the compound of formula 1a based on the total resin weight was prepared.

1% by weight of the polyurethane resin thus obtained (based on the solid content) and 0.05% by weight of the surfactant were dispersed in water to prepare an aqueous dispersion.

Then, a polyester sheet obtained by melt extrusion of a polyester resin obtained through a transesterification reaction and a polycondensation reaction from dimethyl terephthalate and ethylene glycol by a conventional method, and then stretched about 3.5 times in the longitudinal direction at 90 ± 10 ° C. After applying the prepared aqueous dispersion so that the thickness of the coating layer before drying to 5 ± 1μm on one side of the, and then stretch the lateral coating at 230 ± 10 ℃ 3.5 times in the transverse direction at the same time to dry the applied aqueous dispersion poly for adhesive tape An ester film was prepared.

PET-based ink (yellow, manufactured by Daehan Ink Co., Ltd.) used in soft packaging on the surface of the polyester film for pressure-sensitive adhesive tape was coated at 30 μm with a Mayer bar and sufficiently dried, followed by the ink solvent test method described below. The test was carried out and the results are shown in Table 1 below.

In addition, an acrylic resin adhesive (Jongyeon Chemical, trade name SK1717) diluted with methyl ethyl ketone was applied to the surface on which the ink was applied to a thickness of 15 microns with Mayer, and sufficiently dried, followed by high temperature for 72 hours at a temperature of 65 ° C. and a humidity of 85%. Aging was carried out, and the experiment was carried out according to the following environmental resistance test method and the results are shown in Table 1 below.

-Slipness (friction coefficient) test method

The test was performed according to the method defined in ASTM D1894.

Ink Solvent Resistance Test

After the ink printing, the film before the pressure-sensitive adhesive was rubbed by reciprocating the ink layer with a cotton swab coated with methyl ethyl ketone as an organic solvent, and the number of rubs until the surface of the film was visible was measured.

Environmental resistance test

After applying the pressure-sensitive adhesive and drying it, the adhesive surface was adhered to rollers on a sus (policy) plate polished with sandpaper by hot aging film sample as described above, and then divided into three parts, respectively, for 30 minutes at 25 ° C and 30 minutes at 120 ° C. And after maintaining for 30 minutes at 5 ℃ peeled off the adhesive tape for each film sample after confirming the remaining degree of the ink layer remaining on the tape to indicate the grade as follows.

Level 5: 95-100% Level 4 95-85%

Level 3: 85-60% Level 2: 60-40%

<Example 2>

In the same manner as in Example 1, a polyester film for pressure-sensitive adhesive tape was prepared by using a polyurethane resin solid content of 2% by weight when preparing the polyurethane aqueous dispersion as a coating liquid.

<Example 3>

In the same manner as in Example 1, a polyester film for pressure-sensitive adhesive tape was prepared by preparing a polyurethane resin solid content of 10% by weight when preparing the polyurethane aqueous dispersion as a coating liquid.

<Example 4>

In the same manner as in Example 1, but was further added as a slip agent to 0.2% by weight of silica having an average particle diameter of 1.7 to 1.8μm as a coating liquid to prepare a polyester film for pressure-sensitive adhesive tape.

Example 5

In the same manner as in Example 2, it was further added as a slip agent to 0.2% by weight of silica having an average particle diameter of 1.7 to 1.8μm as a coating agent, and the wetting agent (Triton trade name X- 100) 0.1 wt% was further added to prepare a polyester film for adhesive tape.

<Example 6>

In the same manner as in Example 3, but was further added as a slip agent to 0.2% by weight of silica with an average particle size of 1.7 to 1.8μm as a coating agent to prepare a polyester film for pressure-sensitive adhesive tape.

<Example 7>

In the same manner as in Example 6, the weight ratio of the compound of Formula 1 was 90 wt% based on the total resin weight when preparing the polyurethane resin.

Comparative Example 1

The same process as in Example 1, except that the polyurethane aqueous dispersion was not applied to the polyester base film.

Comparative Example 2

In the same manner as in Example 1, a water-dispersible acrylic resin (Tom and Haas, trade name AC503) was used as the coating liquid.

Comparative Example 3

It carried out similarly to Example 1, but used the water-soluble polyester resin (Namsung Co., Ltd., brand name WR-961) as a coating liquid.

<Comparative Example 4>

It carried out similarly to Example 1, but used a water dispersible polyester resin as a coating liquid.

division Slip property (friction coefficient) Solvent resistance Environmental resistance (adhesiveness after high temperature aging) Room temperature (25 ℃, 30 minutes) Heating (120 ° C, 30 minutes) Refrigerated (5 ℃, 30 minutes) Example 1 0.5 25 5 5 5 Example 2 0.49 30 5 5 5 Example 3 0.63 28 5 5 5 Example 4 0.39 25 5 5 5 Example 5 0.38 30 5 5 5 Example 6 0.48 25 5 5 4 Example 7 0.5 27 5 4 5 Comparative Example 1 0.55 4 One One One Comparative Example 2 - 7 3 3 3 Comparative Example 3 - 5 3 2 2 Comparative Example 4 - 5 2 3 2

As can be seen from the results of Table 1 above, in Examples 1 to 7 of the present invention in which a water-dispersible resin composition containing a water-dispersible polyurethane resin as a main component as a coating liquid was applied to a polyester base film, Comparative Examples 1 to 7 were used. Compared with 4, it showed that ink adhesion was remarkably improved by showing excellent durability of at least 7.5 times in solvent resistance to methyl ethyl ketone used as an organic solvent.In the case of the embodiment, even after high temperature aging process, room temperature and high temperature Or, even in a low temperature harsh environment, very good adhesion was shown, while in the comparative example, the desired adhesion could not be obtained.

The present invention is applied to the surface of the polyester film by applying an aqueous dispersion containing a water-dispersible polyurethane resin as a main component to pretreatment, significantly improving ink adhesion, and for adhesive tapes that can exhibit excellent physical properties even under harsh environments of high temperature and high humidity. It is a useful invention for providing a polyester film.

Claims (10)

A water-dispersible poly, prepared by copolymerizing at least one side of a polyester film composed of ethylene terephthalate with at least one 60% by weight of the main repeating unit by copolymerizing a dicarboxylic acid component, a glycol component, a diisocyanate component and a compound represented by the following formula (1): A coating film comprising a urethane resin, a surfactant and a slip agent is applied to a thickness of 0.001 to 1μm polyester film for pressure-sensitive adhesive tape. <Formula 1> In Formula 1, R represents an aliphatic hydrocarbon group having 1 to 12 carbon atoms, and n and m are each independently an integer of 1 to 5. The polyester film for adhesive tape according to claim 1, wherein the diisocyanate component is 2,4-hexamethylene diisocyanate, 2,6-hexamethylene diisocyanate or a compound represented by the following formula (2). <Formula 2> In Formula 2, R 1, R 2, and R 3 independently represent an aliphatic hydrocarbon group having 1 to 12 carbon atoms. The polyester film for adhesive tape according to claim 2, wherein the diisocyanate component is 5-isocyanate-1-isocyanatemethyl-1,3,3-trimethyl cyclohexane or a derivative thereof. The polyester film for pressure-sensitive adhesive tape according to any one of claims 1 to 3, characterized in that the compound of Formula 1 is comprised in the polyurethane resin of 10 to 90% by weight. The polyester film for adhesive tape according to any one of claims 1 to 3, wherein the surfactant is added in an amount of 0.01 to 0.5% by weight based on the solid content. The polyester film for pressure-sensitive adhesive tape of claim 4, wherein the surfactant is added in an amount of 0.01 to 0.5% by weight based on the solid content. The polyester film for pressure sensitive adhesive tape according to any one of claims 1 to 3, wherein a silica filler is added at 0.01 to 0.5% by weight based on the solid content as the slip agent. The polyester film for pressure-sensitive adhesive tape of claim 4, wherein a silica-based filler is added in an amount of 0.01 to 0.5% by weight based on the solid content as the slip agent. The polyester film for pressure-sensitive adhesive tape of claim 5, wherein the silica-based filler is added in an amount of 0.01 to 0.5% by weight based on a solids content as the slip agent. The polyester film for pressure-sensitive adhesive tape of claim 6, wherein a silica filler is added in an amount of 0.01 to 0.5% by weight based on a solids content as the slip agent.