JPH04107456A - Peelable masking film - Google Patents

Abstract

PURPOSE:To uniformly assure both of various film properties and adhesive strength with good balance by forming a peelable film consisting of a peelable film forming material consisting of a specific vinyl alcohol (PVA)-contg. vinyl chloride/vinyl acetate copolymer resin on a synthetic resin film base. CONSTITUTION:The light shieldable and peelable film is formed on the synthetic resin film base subjected to an activation treatment on the surface. The copolymer of 80 to 95wt.% vinyl chloride, 1 to 10wt.% PVA and 0 to 10wt.% vinyl acetate is incorporated as an essential component into the film forming material constituting the peelable film. The vinyl acetate component is preferably low and in this sense, the copolymer consisting of 85 to 92wt.% vinyl chloride, 2 to 5wt.% PVA and 0 to 10wt.% vinyl acetate is adequately used. The peelable masking film having the performance excellent in both of the film properties and adhesiveness and the excellent characteristics is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a masking film that has light-shielding properties and excellent peelability and is used for printing plates, printed circuit board originals, and the like. More specifically, the present invention relates to a peelable masking film that has properties such as tensile strength required for a peelable film when producing a mask plate, and also has excellent adhesion to a base film. .

(Prior art) Conventionally, this type of peelable masking film has (1)
Resin material with film-forming ability, such as nitrocellulose or a copolymer of vinyl chloride and vinyl acetate, (2)
Plasticizing film-forming materials such as light-shielding dyes and pigments, (3) low molecular weight plasticizers such as dibutyl phthalate and dibutyl phthalate, or high molecular weight plasticizers such as epoxy, polyester, or nitrile rubber. A coating agent containing an effective substance, (4) solvent, etc. is applied directly to a synthetic resin film base such as a polyester film or via an adhesive layer (pressure-sensitive adhesive layer), and then dried. It is manufactured by.

The former peelable masking film, which is produced by directly coating onto a film support, is mainly used in ordinary mask plate production operations. The latter peelable masking film with an intervening adhesive layer is for special work in which the peeled film is used again for pasting work.

The peelable masking film of the present invention is particularly used for the former purpose because the film-forming material has excellent adhesion to the film support.

The peelable masking film is processed by a conventional method to form a partially translucent mask plate for pasting a document image or the like.

That is, the peelable masking film is usually placed over the original on a light table, and the area where the original image is to be pasted is specified on the light-shielding peelable layer. Make a score line with a knife cutter around the x, or connect it to a CAD device.
Score lines are drawn with a Y cutter, and the coating is peeled off in areas surrounded by these score lines or score lines to form a partially translucent mask plate.

During the above-mentioned incision (hereinafter referred to as cutting) operation, the quality of the releasable film is evaluated based on the following factors.

The hardness of the releasable film and the sharpness of the film greatly affect the work efficiency in the case of hand cutting, and the reliability of the score line and the life of the cutting edge in the case of machine cutting such as an XY cutter.

In addition, the adhesion of the releasable coating to the film support depends on the workability of flipping up one end of the coating surrounded by the cut line with the edge of a knife (hereinafter referred to as "splashability"), and This affects the generation of resistance when separating from the area cutout, and the accidental separation of parts that should not be separated when the mask plate is used for printing plate making.

Furthermore, the strength of the releasable film is determined by the deformation of the film when it is sprung,
It is related to cracking or unnecessary elongation and breakage during separation.

In consideration of the above-mentioned required performance, various proposals have been made to improve the performance of releasable coatings.

For example, nitrocellulose or vinyl chloride, which has high coating strength (tensile strength), is used as the coating forming material so that the coating in the area surrounded by the cut line can be peeled off continuously and uniformly without breakage during removal work. There is a proposal to use a copolymer of vinyl acetate and vinyl acetate.
Publication No. 011).

However, these film-forming materials have poor adhesion to the base film support, such as the polyester film support commonly used in this type of field, and in order to obtain sufficient light-shielding properties, large amounts of light-shielding dyes or Since the addition of pigments makes the film brittle, plasticizers are actually added to obtain appropriate adhesion and film properties (stress-strain properties). In products containing plasticizers, if the amount added is small, the film will be hard (and brittle) and will have poor adhesion to the support; if the amount added is large, the adhesion will increase, but the film will be soft and stretchable, and Blocking will occur.

Even if a removable film with appropriately adjusted physical properties and adhesion is formed by adding a plasticizer, the physical properties and characteristics of the film will change due to a slight temperature change during detachment. In order to obtain peel properties, it is necessary to strictly control the selection and amount of plasticizer added, which inevitably reduces the cuttability, cut-up properties, and various properties of the peelable film required for release. The current situation is that

(Problems to be Solved by the Invention) The present invention solves the above-mentioned drawbacks of the prior art, namely, peelable masking with little flexibility, which attempts to balance the contradictory physical properties and adhesion of a peelable film using a plasticizer. This is an attempt to improve the film's deficiencies.

The present invention specifically requires a specific vinyl chloride/vinyl alcohol/vinyl acetate copolymer as a releasable coating for a peelable masking film for a support film whose surface has been activated by corona treatment or the like. It has been discovered that the film has excellent performance in both physical properties and adhesion, and that the adhesion force can be adjusted independently without affecting the film properties. Film provided.

[Structure of the Invention] (Means for Solving the Problems) To summarize the present invention, the present invention comprises forming a light-shielding peelable film on a synthetic resin film support whose surface has been activated. In the peelable masking film, the film-forming material constituting the peelable film is vinyl chloride......80-95% by weight vinyl alcohol...1-10% by weight acetic acid Vinyl: This relates to a peelable masking film characterized by containing 0 to 10% by weight of a copolymer as a main component.

Hereinafter, the configuration of the present invention will be explained in detail.

The first feature of the peelable masking film of the present invention is that a surface-activated synthetic resin film support is used. In the present invention, the surface activation means applied to the synthetic resin film support include corona discharge treatment, electron beam irradiation treatment, ultraviolet irradiation treatment, flame treatment, plasma treatment, etc., which are commonly used in the art. All you have to do is adopt the means. By these surface activation means, COOH groups, OH groups, peroxides, etc. are formed on the surface of the synthetic resin film support, which improves the adhesive strength and peel strength of adhesives and paints. This is well known. In the present invention, these surface activation means are employed in order to improve the adhesion of the specific vinyl chloride/vinyl alcohol/vinyl acetate copolymer described above to the support film.

The synthetic resin film support used in the present invention is
There are transparent films such as vinyl chloride film, styrene film, cellulose di- or triacetate film, polycarbonate film, polyethylene terephthalate film, polybutylene terephthalate film, etc., especially biaxially stretched polyethylene terephthalate film. Taret is preferred because it is excellent in terms of tensile strength, tear strength, dimensional stability, and the like.

The second feature of the peelable masking film of the present invention is that the film-forming material is made of a specific copolymer component. In the present invention, in order to exhibit the balanced physical properties of the above-mentioned film and adhesion, which are particularly required for the peelable coating of the peelable masking film, 80 to 95% by weight of vinyl chloride and 1 to 10% by weight of vinyl alcohol are used. , a copolymer consisting of 0-1[1i% by weight of vinyl acetate is used.

In the present invention, a support film whose surface has been subjected to an activation treatment is used. 2. Even when an inexpensive copolymer with a small vinyl alcohol component is used, sufficient adhesion is achieved.

The copolymer used in the present invention is, for example, commercially available vinyl chloride for paints, vinyl acetate copolymer resin (vinyl chloride 80
~95% by weight, vinyl acetate 5% to 20% by weight, 5% weight average polymerization degree 200 to 800) to a concentration of approximately 10% in a ketone such as acetone or methyl ethyl ketone alone or in a mixed solvent with an aromatic solvent such as toluene or xylene. Dissolve, 30-5
A resin solution can be easily prepared by adding and stirring an ethanol solution of caustic potash or caustic soda while maintaining the temperature at 0° C., and separating the resulting acetate.

As described above, the vinyl acetate component is converted into a vinyl alcohol component by saponification, but some amount remains due to the saponification reaction. From the viewpoint of adhesion to the support film, it is desirable that the vinyl acetate component be as low as possible, but in the present invention, since the surface of the support film is activated, the vinyl acetate component may be greater than the vinyl alcohol component. . From this meaning, vinyl chloride 85 to 92% by weight, vinyl alcohol 2
A copolymer comprising 5% by weight of vinyl acetate and 0-10% by weight of vinyl acetate is preferably used.

The reason for using the copolymer having the above composition in the present invention is as follows. If the surface of the support film has not been activated by corona treatment, etc., the adhesion to the support film is likely to be due to the hydroxyl group content in the above copolymer, and the vinyl alcohol content ratio increases. The adhesion of the film to the film improves by 15%.
If the content exceeds 5%, it will be difficult to remove a large area, and if the content is less than 5%, the adhesion to the support will be poor, and if the peel film with scored lines is bent together with the support film, the markings will be difficult to remove. Lifting of the peel layer occurs along the lines.

On the other hand, even if the vinyl alcohol content is within the above range, vinyl chloride content exceeding 95% has poor solubility (difficult to create a practical coating solution. If the residual amount exceeds 5%, the adhesive force with the support film will decrease and a practical peel film will not be obtained, and the vinyl acetate content in the copolymer composition will be 5% or less, preferably 3% or less. Therefore, it is necessary to sufficiently saponify the vinyl acetate in the raw resin.However, if the surface of the support film is activated by corona treatment or the like, the adhesion of the coating agent will improve. The above-mentioned specific vinyl chloride/vinyl alcohol/vinyl acetate copolymer is used, which has a small vinyl alcohol component and is inexpensive.

In the present invention, the copolymer preferably has an average degree of polymerization (weight) of 200 to 800. this is,
Copolymer resins with the above composition having a polymerization degree of less than 200 have a low solution viscosity and can be used to prepare coating solutions with high solids content, but the dried film has a weak tensile strength, while those with a polymerization degree of more than 800 have a low tensile strength of the film. is sufficient, but the solution viscosity is too high,
A practical coating solution cannot be prepared, and from this point of view, the degree of polymerization is preferably from 200 to 800.

The film-forming material constituting the releasable film of the present invention has the above-mentioned copolymer as a main component, and may be composed of other film-forming materials. This type of film-forming material includes vinyl chloride, vinyl acetate copolymers; vinyl chloride, vinyl acetate, maleic acid copolymers; vinyl chloride, vinylidene chloride copolymers; polymethacrylic acid esters, diacrylic and styrene copolymers; Any resin may be used as long as it is compatible with the above-described copolymer resin of the present invention, such as styrene, butadiene, block, and copolymers.

In the present invention, in order to form a light-transmitting peelable film on the synthetic resin film support described above, a specific vinyl chloride/vinyl alcohol/vinyl acetate copolymer is used as a film-forming material, and ( a) Light blocking agent, Fb) Plasticizer, (C
) A surface roughening agent, (d) an organic solvent, etc. are optionally and appropriately blended to prepare a coating agent for forming a peelable film, and this is coated on a film support by an appropriate method and dried. Bye.

As the light shielding agent (a) mentioned above, Solvent Yellow 3
3 FC: 1.47000), Solvent Red 18
FCl, 21260), Solvent Brown 5 (C1
12020), Solvent Green 3 fcl, 615
Oil-soluble dyes having a light-shielding property against ultraviolet rays, such as 651, or organic pigments, such as quinacridone, perylene red, disazo yellow, and disazo orange, are used.

As the plasticizer (b) mentioned above, dioquidyl phthalate, tricresyl phosphate, dibasic acid esters of polyethylene glycol, epoxidized vegetable oil, chlorinated paraffin, nitrile rubber, etc. are used depending on the film properties of the release film. It can be blended so as not to impair adhesion.

The above fc) roughening agent has a particle size of 0.3 to 1.
Inorganic fine powders such as silicate, calcium carbonate, clay, etc. in the 2 micron range, methyl methacrylate resin, benzoguanamine resin.

Organic fine powder made from melamine resin or the like is added to the coating solution as appropriate to prevent glare on the surface of the peel coating and to improve suction during printing with a vacuum printer.

fd) The organic solvent mentioned above is acetone.

Ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, butyl acetate,
These ester solvents are used alone or in combination, and aromatic solvents such as benzene, toluene, and xylene can also be mixed therein as a diluent.

The peelable film-forming material (paint) of the present invention comprising the above-described components is applied to a base film support whose surface has been activated by a desired coating method to a desired thickness, for example, a dry thickness of 2.
It is applied to a thickness of 0 to 25 μm and dried to form a peelable film.

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the Examples.

(Example 1) The surface of a uniaxially stretched polyethylene terephthalate film having a thickness of 100 μm was subjected to a corona discharge treatment. The conditions for the corona discharge treatment were to apply a high frequency power of 15 KHz of 8 W per square centimeter using a Kasuga Denki Co., Ltd. liver-80 leaf type processing machine, and to achieve a wetting tension of 52 dynes/c on the film surface.
I did this so that it would be m.

In addition, there are three types of commercially available vinyl chloride/vinyl acetate copolymer resins with different compositions (A, D).

(1)-1) is used as a raw material and hydrolyzed to produce six types of vinyl chloride/vinyl acetate/vinyl alcohol ternary copolymers (B, C, E, F, G) with different vinyl alcohol contents.

■) was prepared.

Next, a paint having the composition shown in Table 1 was prepared and applied to one side of the polyethylene terephthalate film, which had been subjected to the corona discharge treatment as described above, to a dry thickness of 23 microns using a variable gap applicator. , 12
A peel film was prepared by drying for 5 minutes in a constant temperature bath at 0°C. Comprehensive evaluation of the properties of each sample as a peel film was compared from the viewpoints of 1) Thin line stability 2) Film lifting 3) Splashing properties 4) CAD properties 5) Peeling resistance 6) Film strength 7) Film elongation did.

Thin line stability indicates the stability of the film when a thin line-shaped film with a width of 0.5 mm and a length of 5 cm is made on the support film and the film is scratched with the tip of the thumb in a direction perpendicular to the thin line. So, if the film comes off after 1-3 scratches, ×, 3-9
Those with a durability of 10 times or more were rated △, and those with 10 times or more were rated ○.

The lifting of the film can be determined by cutting two 5 cm long lines perpendicular to each other with a utility knife on the peel film, placing the intersection approximately in the center, and twisting the supporting film 10 times with both hands. A case where the film is lifted in a considerable area is marked as ×, and a case where the film is lifted only at the intersection is marked as △.
.

The case where there was no floating was marked as ○.

The repellency is ○ if it can be easily repelled, and △ if the repellent cannot be repelled unless the cutting edge of the cutter knife is bent at an angle of 30 degrees or less to the surface of the peel film. Cases where a trial was required were marked as ×.

The CAD characteristics are ○ for samples that require less pressure when cutting with an XY plotter, △ for samples that require medium pressure, and △ for samples that require a considerable amount of pressure, or those that have sticky or rubbery properties even with a light load. Cases where vibration or chatter occurred at the cutting edge were rated as ×.

Peeling resistance was measured by peeling off one end of the 1 cm wide and 20 cm long Zamble by about 12 cm and using a tensile tester (manufactured by Naji Seisakusho, Autograph AG) on the supporting film end and the detached end.
S-50B) was set in a holder, and the average peel strength was measured while the peeling continued.

To determine the strength of the coating, a detachable piece with a width of 1 cm and a length of 15 cm was prepared, and a tensile tester was set so that the distance between the holders was 10 cm, and the breaking strength was determined.

In addition, the elongation of the film until it broke was measured and the elongation rate was calculated.

Table 2 shows the composition of the sample resins and the results of their evaluation.

[Effects of the Invention] The peelable masking film of the present invention is made of a specific vinyl alcohol-containing vinyl chloride/vinyl acetate copolymer resin on a synthetic resin film support whose surface has been activated by corona discharge treatment or the like. A releasable film is formed using a removable film-forming material.

As a result, when removing (peeling) a peelable masking film, both the physical properties and adhesion of the peelable film, which are particularly required, are ensured in a well-balanced manner. Efficiency (can be done)

Patent applicant: Toyo Packaging Materials Co., Ltd. Reason Man

Claims (1)

[Claims] 1. A peelable masking film in which a light-shielding peelable film is formed on a synthetic resin film support whose surface has been activated, wherein the film-forming material constituting the peelable film is , Vinyl chloride...80-95% by weight
Vinyl alcohol: 1 to 10% by weight Vinyl acetate: 0 to 10% by weight of a copolymer. Peelable masking film. 2. The peelable masking film according to claim 1, wherein the surface activation means is selected from corona treatment, electron beam irradiation treatment, ultraviolet irradiation treatment, flame treatment, and plasma treatment. 3. The peelable masking film according to claim 1, wherein the synthetic resin film support is a biaxially stretched polyester film. 4. The copolymer of the film-forming material is vinyl chloride...85 to 92% by weight
The peelable masking film according to claim 1, which comprises vinyl alcohol: 2 to 5% by weight vinyl acetate, 0 to 10% by weight. 5. The weight average degree of polymerization of the copolymer of the film forming material is 200.
The peelable masking film according to claim 1 or 4, wherein the peelable masking film has a molecular weight of 800 to 800.