JPH02248435A - Easily bondable polyester film - Google Patents

Abstract

PURPOSE:To obtain a film having excellent adhesion to various coating materials, inks, toner, etc., especially diazo dyes, UV inks, etc., by coating the surface of a polyester film with a specified primer. CONSTITUTION:A primer layer formed by crosslinking a hydroxyliated acrylic copolymer resin (A) with a glycidylamine compound (B) is applied to at least one surface of a polyester film. A hydroxylated (meth)acrylate resin of a second- order transition point of about 20-95 deg.C can be used as component A and is obtained by copolymerizing a hydroxylalkyl (meth)acrylate with other comonomers [e.g. alkyl(meth)acrylate]. A compound having at least one tert. amino and at least two glycidyls in the molecule can be used as component B and is desirably a compound of formula I. The mixing ratio of component A to component B is desirably 60-99wt.% A to 1-40wt.% B. The primer layer can be formed by applying an aqueous composition of components A an B and drying and heat-setting the film.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an easily adhesive polyester film, and more specifically, for example, chemical matte paint, offset ink,
The present invention relates to a polyester film that has excellent adhesion to paints, inks, toners, etc. such as UV inks, diazo paints, magnetic paints, and electrophotographic toners.

<Prior art> Polyester films, especially biaxially oriented films of polyethylene terephthalate, have excellent mechanical properties, heat resistance, and chemical resistance, so they are used in magnetic tapes, photographic films, packaging films, metallizing films for capacitors, and electronics. The demand for it as a material for insulating films, OHP films, etc. has been growing particularly rapidly recently. However, due to crystal orientation, polyester film has high surface cohesion and poor adhesion to various paints.

Therefore, in order to improve the surface properties of polyester films, corona treatment, plasma treatment or flame treatment are used. However, these means have the disadvantage that their performance deteriorates over time.

A method for overcoming this drawback is chemical treatment. However, there are problems in practical use, such as the chemical being toxic and the volatilization of its vapor contaminating the environment.

Another known method is to apply an easily adhesive coating onto a biaxially stretched polyester film to provide a primer layer. However, this method also involves safety and hygiene problems such as environmental deterioration due to solvent volatilization, and the risk of frequent surface defects due to adhesion of dirty slick dust in the coating cloud.

Therefore, if this brimer treatment is performed during the polyester film forming process using a water-based coating, there will be less dust adhesion in a clean environment, and since it is a water-based coating, there will be no risk of explosion or environmental deterioration. It is also advantageous in terms of film performance, economy, and safety.

Because of these advantages, it has been proposed to use water-soluble or water-dispersible polyurethane or copolymerized polyester resins as the brimer. However, the primer layer has drawbacks such as blocking between the films due to changes in temperature and humidity during storage, and insufficient adhesion to diazo paints and UV inks.

<Object of the Invention> An object of the present invention is to provide a polyester film that has excellent adhesion to various paints, inks, toners, etc., especially diazo paints, UV inks, etc.

<Configuration/Effects of the Invention> According to the present invention, an object of the present invention is to provide a primer in which (A) a hydroxyl group-containing acrylic copolymer resin is crosslinked with (B) a glycidyl amine compound on at least one side of a polyester film. This is achieved by an easily adhesive polyester film characterized by having a layer.

In the present invention, polyester is a linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. Specific examples of such polyesters include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly(1,4-cyclohexylene dimethylene terephthalate), polyethylene-2,6-phthalene cyclopoxylate, and the like. Copolymers of these or blends of these with small proportions of other resins are also included. This polyester may contain a small amount of inorganic or organic fine particles to improve slipperiness. Such fine particles include inorganic fillers such as titanium oxide, calcium carbonate, silica, barium sulfate, etc., and organic fillers such as acrylic resin, silicone, benzoguanamine, Teflon, epoxy, etc. Further, it may contain an adhesion or antistatic agent such as polyethylene glycol (PEG) or sodium dodecylbenzenesulfonate. The base film of the present invention can be obtained by melt-extruding this polyester into a film by a conventional method, and further oriented crystallization by biaxial stretching in the longitudinal and transverse directions and crystallization by heat treatment.

The <A) hydroxyl group-containing acrylic copolymer resin used for forming the primer layer in the present invention has a secondary transition point of 20
It is a hydroxyl group-containing (meth)acrylic acid ester resin with a temperature of ~95°C. Preferably, the resin has no free carboxyl groups. Such resins may contain hydroxyl group-containing monomers such as hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc. and other copolymerizable monomers such as alkyl (meth)acrylates ( Here, the alkyl group is a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group,
(t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); (meth)acrylamide, N-alkyl (meth)acrylamide, and N,N-dialkyl (meth)acrylamide (here, the alkyl group is a methyl group, an ethyl group) , n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N-alkoxymethyl (meth)acrylamide and N,N-dialkoxymethyl (meth) ) acrylamide (where the alkoxy group is a methoxy group,
ethoxy group, butoxy group, inbutoxy group, etc.), N-methylol (meth)acrylamide, N,N-dimethylol (meth)acrylamide, N-phenyl (meth)acrylamide, etc.; glycysyl (meth)acrylate Epoxy group-containing monomers such as vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, alkyl maleic acid monoester, acrylonitrile, metacyclonitrile, vinylidene chloride, ethylene, propylene, vinyl chloride, vinyl acetate, butadiene, etc. Obtained by copolymerizing two or more types. The main components of the monomer constituting this copolymer are preferably methyl methacrylate (MMA) and ethyl acrylate (EA).In particular, it is preferable that the MMA/EA ratio is in the range of 0.5 to 3 in terms of molar ratio. More preferably, it is in the range of 0.7 to 2. The total amount of MMA and EA is preferably 50 to 98% in total mole %, and more preferably 80 to 96%.

In addition, the amount of hydroxyl group-containing monomer as an essential component is 0.5
~15 mol% is preferred. More preferably, it is 1 to 10 mol%.

If the secondary transition point of such a resin is less than 20° C., a blocking phenomenon occurs between the films due to the adhesiveness of the primer layer. Further, if the temperature is higher than 95°C, the primer layer becomes hard and brittle, resulting in a disadvantage that adhesiveness with the polyester film decreases. This secondary transition point is preferably 30 to 70°C, more preferably 40 to 70°C.

In the present invention, the compound (B) used for crosslinking the hydroxyl group-containing acrylic copolymer resin (A) is a glycidylamine compound. This glycidylamine compound is a compound having at least one tertiary amino group and two or more glycidyl groups in the molecule, and preferable examples include the following. In addition to these compounds, a small amount of water-soluble or water-dispersible polyglycyl compounds such as trimethylolpropane triglycidyl ether and glycerin triglycyl ether can also be used.

In addition, a compound that promotes the reaction between a hydroxyl group and a glycicyl group (reaction promoting compound) can be used, such as a compound containing a tertiary amino group, a compound having a nitrogen-containing ring structure and its salt, a quaternary ammonium Examples include salt compounds. Specific examples include tri-n-butylamine, dimethylaminobenzene, 2,4.
6-) Lis(dimethylaminomethyl)phenol, 2-
Methylimidazole, 1,8-diazo-bicyclo(5,
4,0) undecene-7, tetramethylammonium chloride, and the like.

The weight percent ratio of (A) hydroxyl group-containing acrylic copolymer resin and (B) glycidyl amine compound in the brimer layer is as follows: component (Al: 60-99%, component (B): 1-40%).
It is preferable that A more preferable range is component (A)
is 70 to 98%, and component (B) is 2 to 30%.

The primer layer in the present invention can be formed by applying a coating liquid containing a core layer forming component, preferably an aqueous liquid, onto a polyester film, drying and curing with heat.

The coating liquid is preferably an aqueous liquid such as an aqueous solution or a water emulsion liquid. This aqueous liquid may contain some amount of organic solvent to stabilize the dispersion of the solid components.

This aqueous brimer coating liquid is obtained by dissolving or dispersing the above two essential components in an aqueous medium, and a catalyst and a wetting agent are added as necessary. The wetting agent includes anionic, cationic and nonionic surfactants. This surfactant lowers the surface tension of aqueous liquids by 40 d.
yne/cm or less and promotes wetting of the polyester film. Examples include polyoxyethylene alkylphenyl ether, polyoxyethylene-fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, alkyl sulfonate, quaternary amine salt, betaine type surfactant, and the like. In addition, antistatic agents, ultraviolet absorbers, pigments, organic fillers, inorganic fillers,
A lubricant, an anti-blocking agent, etc. may be used in combination.

The step of applying this aqueous brimer coating liquid is preferably carried out on the surface of the substrate immediately after melt extrusion and casting of the polymer, or immediately after stretching in either the vertical or horizontal direction. The usual method is to apply a primer layer on a uniaxial film stretched in the longitudinal direction.
Subsequently, the film is laterally stretched while being heated, and the film is further heat-set at a high temperature, and the heat-setting of the primer layer is completed. Any known method can be used to coat the primer layer on the polyester film. For example, a spray coating method, an ener knife method, a reverse coating method, a kiss coating method, a gravure coating method, a Meyer bar method, a roll plush method, etc. can be applied. The concentration of the coating liquid applied varies depending on the coating method, but -m
It is 0.5 to 50% by weight. The amount of application is 1 in wet amount.
It is preferable that it is 20 g/rrr.

The polyester film having a primer layer of the present invention has excellent adhesion properties, and is particularly suitable for chemical matte soils, membranes, telephone cards, labels, microfilms, etc.
It is useful as a base material for industrial films such as diazo films and OHP films, and magnetic recording media such as video tapes, audio tapes, computer tapes, and floppy disks.

<Examples> The present invention will be explained in detail below using Examples. Note that various values in the specification were measured as follows. In addition, "parts" in the examples represent parts by weight.

(1) 6 μm (dry) of diazo glow paint having the following composition is applied onto the polyester film coated with adhesive primer.

"Evaluation paint" Cellulose acetate butyrate 70 parts DH-200B
F4 (Daito Chemical) 9 parts 5O-100
(Daito Chemical) 7 parts citric acid
8 parts oxalic acid
6 parts After this diazo photosensitive layer was developed with ammonia, cellophane tape was pressed onto the photosensitive layer with a roller, the humidity was controlled at 23° C. for 16 hours, and then it was strongly peeled off.

Then, the diazo photosensitive layer is placed on the polyester film side. all that's left half torn off Everything turned to the side Judge by.

(2) Blocking property...○ ...△ ...× Brimer-coated polyester film 15 x 10 cm
Cut it out and stack the brimer sides together to weigh 50kg.
After applying a load of /cm2 and holding at 50°C for 16 hours,
Peel strength is measured in the width direction of 10 cm.

Examples 1 to 3 A lubricant-containing polyethylene terephthalate having a polymer intrinsic viscosity of 0.61 measured in orthochlorophenol at 35°C is extruded from a T-die, and while electrostatically applied on a drum cooled to 40°C, the thickness is An unstretched film with a diameter of 152 μm was prepared, then heated to 93° C. and stretched 3.6 times in the machine direction, and then a brimer coating liquid having the following composition was applied onto the uniaxially stretched film by a kiss coating method.

Coating liquid composition> ■Acrylic copolymer resin with the composition shown in Table 1 80 partsN, N, N', N'-tetraglycidyl-m-xylene diamine 5 parts■Nonionic surfactant 15 parts ( NOF ■Nonion NS-208,5>The wet application amount at this time is:
5%X3g/rr? Met.

Thereafter, it was laterally stretched 3.6 times at 102°C, and then stretched at 223°C.
A biaxially stretched (easily adhesive) polyester film having a thickness of 75 μm was obtained by heat treatment at °C.

The performance of this film is shown in Table 2.

The abbreviations in the table above are as follows.

MMA, methyl methacrylate EA; ethyl acrylate NMAA; N-methylol acrylamide HEMA;
2-Hydroxyethyl methacrylate MAA; Methacrylamide Example 4 To 88 parts of the acrylic copolymer resin in Example 2, Tetrad C5 part manufactured by Mitsubishi Gas Chemical Co., Ltd., Dinacol EX-3131 part manufactured by Nagase Kasei Co., Ltd. and Nippon Oil & Fats Co., Ltd. A brimer solution was prepared by adding 5208.56 parts of nonionic N.

A brimer-coated polyester film was obtained in exactly the same manner as in Example 1, except that this brimer liquid was used.

The performance of this film is shown in Table 2.

Comparison Example 1 For comparison, the performance of a polyester film not coated with any primer is shown in Table 2.

As is clear from Table 2, the primer-coated polyester film of the present invention has excellent adhesion and anti-blocking properties.

Claims (1)

[Claims] An easily adhesive polyester film having a primer layer formed by crosslinking (A) a hydroxyl group-containing acrylic copolymer resin with (B) a glycidylamine compound on at least one side of the polyester film.