JPS62257844A - Easily adhesive polyester film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an easily adhesive polyester film, and more particularly, it has a primer layer that exhibits excellent adhesion to acrylic inks and coating agents and has excellent blocking resistance. This invention relates to an easily adhesive polyester film.

BACKGROUND OF THE INVENTION It is known to melt extrude and form films from thermoplastic polyesters, such as polyethylene terephthalate or its copolymers, polyethylene naphthalate or its copolymers, or blends thereof with small proportions of other resins. It is also known that the resulting two-wheel stretched and heat-set polyester film has better heat resistance, gas barrier properties, electrical properties, and chemical resistance than films made of other resins. However, since the surface is highly crystal oriented, the surface has high cohesion and poor receptivity to paints, adhesives, inks, etc.

Therefore, various methods have been proposed to impart these receptivity to the surface of such a polyester film, and one known method is to provide a primer layer (undercoat layer) to form a thin surface area different from that of the base film. There is.

This undercoat layer first requires strong adhesion to the polyester film, so conventionally it has often been coated with a coating liquid using polyester resin, polyurethane resin, or polyacrylic resin that has this property. There is. However, when this polyester resin or polyurethane resin is used for the primer layer (undercoat layer), it is said that it does not exhibit sufficient adhesion to acrylic inks and paints such as U ink, conductive paint, and UV curing hard coat paint. There are problems, especially in terms of adhesive durability under high temperature and high humidity conditions (e.g. 60°C, 90% RH).

Another problem is that the adhesive durability under sunlight is extremely low. In addition, polyurethane resins and polyacrylic resins are sticky, and when a polyester film coated with these resins is rolled up, the back side of the polyester film and the primer layer adhere to each other and cause blocking, making it impossible to commercialize the product.

Purpose of the Invention As a result of intensive research to develop a primer layer that solves these problems, the present inventor found that a primer layer with a specific composition has excellent adhesion to polyester films and is highly resistant to top coats, especially acrylic inks and coating agents. The present invention was achieved based on the discovery that it exhibits excellent adhesive properties and excellent blocking resistance.

Therefore, an object of the present invention is to provide an easily adhesive polyester film having the above characteristics.

Structure/Effects of the Invention The object of the present invention is to provide an easy-adhesive film in which one or both sides of a polyester film are coated with an easy-adhesive primer layer, the primer layer comprising polyester resin, melamine resin, and A coating liquid containing a comb-shaped graft polymer having polymethyl methacrylate as a backbone chain and poly2-hydroxyethyl methacrylate as a branch chain, and in which the graft polymer accounts for 5 to 50% by weight based on the total base of these three components. This is achieved by an easily adhesive polyester film characterized by being formed with a coating.

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-
Examples include 2,6-naphthalene dicarboxylate,
Copolymers of these or blends of these with small proportions of other resins are also included.

The polyester film in the present invention is obtained by melt-extruding the linear saturated polyester resin, making it into a film form by a conventional method, and subjecting it to orientation crystallization and heat treatment crystallization. It is preferable that the crystal orientation is such that the value measured at medium temperature [at a heating rate of 10° C./min] usually exhibits a value of 4 cal/9 or more.

In the present invention, the primer layer provided on one or both sides of the polyester film contains a polyester resin, a melamine resin, and a comb-shaped graft polymer having a back chain of polymethyl methacrylate and branch chains of poly 2- and droxyethyl methacrylate. It is formed by coating with a coating liquid.

This polyester resin is a polymer soluble in a rich solvent, and examples of the acid component include terephthalic acid, isophthalic acid, and sodium sulfophthalic acid.

Examples of the glycol component include ethylene glycol, diethylene glycol, neopentyl glycol, tetramethylene glycol, propylene glycol, trimethylene glycol, and hexamethylene glycol. Polyester resins are usually copolymers and are also commercially available. Specifically, Toyobo ■ “Byron 200” “Byron 300”
, Hitachi Chemical Nispel 310" Nispel 151
Examples include Soken Kagaku ■'Thermolac 3 101''.

In addition, commercially available melamine resins can be used as the melamine resin, and specifically, Hitachi Chemical ((2) “
Melan 20", three-phase chemical ■"Nikaratsuku MS-11
” etc. can be exemplified.

The ratio of polyester resin and melamine resin used is 10
: 90 to 90:10 (wt%) is preferable, more preferably 1
0:90 to so:so (wt%) is preferred, and 20:80 to 40:60 (wt%) is particularly preferred. If the amount of melamine resin is too small, the adhesive force will be low, while if it is too large, the flexibility of the primer layer will be reduced.

Furthermore, the type graft polymer is 9? A comb-shaped graft polymer in which the chain is polymethyl methacrylate and the branch chains are poly-2-hydroxyethylene methacrylate, and this backbone chain exhibits hydrophilicity, resulting in polyester resins and polyurethane resins.

It binds or exhibits strong affinity with acrylic resins, melamine resins, etc., while its branch chains exhibit hydrophilic properties and adhere closely to hydrophilic resins, or act as a brimer for acrylic paints. When added to a coating liquid, this comb-shaped graft polymer has excellent interfacial migration properties, and exhibits sufficient functionality even when added in a small amount. A specific example of this is Soken Chemical ■“Comb-shaped Polymer L”
-20, L-40", Toagosei■"GC-10"'"G
Examples include H-20.

The proportion of the comb-shaped graft polymer to be used is preferably 5 to 50% by weight, more preferably 10 to 35% by weight, based on the total weight of the polyester resin, melamine resin, and graft polymer. If the usage ratio is less than 5% by weight, the base of branched chain components that have a surface-modifying effect will tend to be insufficient, resulting in a decrease in brimer performance.On the other hand, if it exceeds 50% by weight, blocking resistance will decrease, resulting in a polyester film. This is not preferable because close contact development with the back surface occurs.

Through the use of a comb-shaped block polymer, the surface of the primer layer is covered with a poly-2-hydroxyethyl methacrylate component, e.g. acrylic paint.

It is also believed that it exhibits an excellent brimer effect on acrylic inks, U-curable printing inks, conductive acrylic paints, UV-curable hard coat paints, etc. When forming a primer layer on the surface of a polyester film,
For example, a polyester resin and a melamine resin are dissolved in an organic solvent such as ethyl acetate, methyl ethyl ketone, toluene, methyl cellosolve, etc., a solid graft polymer is added to the resulting solution, and the solid graft polymer is sufficiently stirred and dissolved to prepare a coating liquid. A method of coating with a coating liquid is preferred. Coating methods include barcode method and kiss coat method.

Conventionally known methods such as the doctor blade method, gravure coating method, and reverse coating method can be used.

The coating thickness may be such that the thickness after drying is 0.1 to 560 μm. There is no change in adhesion depending on the thickness of the primer layer, but in order to form a uniform primer layer on the surface of the polyester film, it is preferably 0.1 μm or more, and if it is 5.0 μm or more, economic loss will be large. .

The polyester film with the primer layer thus obtained is. Acrylic ink, UV curing ink,
It exhibits particularly excellent adhesion to conductive paints, UV-curable hard coat paints, etc., as well as chemical matte paints and toners for electrophotography.

It is also useful for gelatin paints and has the feature of not being sticky and exhibiting good blocking resistance.

Example The present invention will be further explained below with reference to Examples.

In addition, each characteristic of the film was measured by the following method.

1. Blocking resistance The coated surfaces of the films are stacked together and a load of 3 K'J/ci is applied for 17 hours in an atmosphere of 60° C. and 80% RH, and then the peel strength between the films is measured and used as a measure of blocking.

2. Adhesiveness Apply the paint on each primer layer using the following method,
The coated film obtained by drying and curing is heated at 60℃9
Stored in a 0%RH atmosphere for one week, then JIS K
Adhesion is evaluated by the base grain evaluation method in accordance with -5400.

(1) Coating method ■ Coating of UV curable ink Moroboshi ink ■ “UVS-PCD Beni T” Insenwo R
It is printed to a coating thickness of about 1.0 μm using a type I-1 (testing machine according to JIS, K-5701 color developing device) and cured by UV irradiation. In addition, UV irradiation is done by Nippon Battery E.
The test was carried out at a speed of 3 m/min under 80 W/cm.

■ Coating of silver paste ink Mauve Kasei) (3) Apply ``Dotite FA-303'' to a thickness of approximately 1.0 μm using the doctor blade method, 1.
Dry at 20°C for 20 minutes.

■ UV curing hard coat GAF “Gafard N” (1233” (1)
Coat a 50% solution of Lt ethyl ketone to a thickness of approximately 4.0μTrL (after drying) using a bar coater, and apply UV irradiation (
Using the equipment mentioned above, the curing conditions were 80 W/Gl, and the speed was 0.5.
m/min).

[2) i: Evaluation Examples 1 to 4 and Comparative Example 1.2 of i-th board test Polyester resin (manufactured by Hitachi Chemical, trade name: Nispel 15
10") and 70 parts by weight of melamine resin (trade name: "Nicalac MS-11" manufactured by Sansho Chemical Co., Ltd.) were mixed with toluene, ethyl acetate, and methyl ethyl ketone (1:1:1).
) Dissolved in 900 parts by weight of a mixed solvent, and added to the resulting solution as a solid graft polymer with the product name "L-2" manufactured by Soken Chemical Co., Ltd.
A brimer coating liquid was prepared by adding 0'' in the proportions shown in Table 1.

Each of these coating liquids was applied to a polyester film (trade name: °° Tetron Film S-100μ'' manufactured by Yoto) using a bar coater so that the thickness after drying was approximately 1.0 μm. 15 to carry out
The test was carried out at 0°C and a residence time of 1 minute.

Table 1 shows the results of examining the blocking resistance and adhesion of the obtained primer coated polyester film.
Shown below.

Claims (1)

[Claims] An easy-adhesive film in which one or both sides of a polyester film is coated with an easy-adhesive primer layer, the primer layer having a backbone chain of polyester resin, melamine resin, and polymethyl methacrylate, and a branch chain of poly2-hydroxyethylene methacrylate. 1. An easily adhesive polyester film comprising a comb-shaped graft polymer, and formed by coating with a coating liquid in which the graft polymer accounts for 5 to 50% by weight based on the total amount of these three components.