JPH04107455A - Peelable masking film - Google Patents

Abstract

PURPOSE:To uniformly assure both of various film properties and adhesive strength with good balance by constituting a peelable film of a specific vinyl alcohol (PVA)-contg. vinyl chloride/vinyl acetate copolymer. CONSTITUTION:The light shieldable and peelable film is formed on a synthetic resin film base. The copolymer of 80 to 95wt.% vinyl chloride, 5 to 15wt.% PVA and 0 to 5wt.% vinyl acetate is incorporated as an essential component into the film forming material constituting the peelable film. Namely, the vinyl acetate component is converted to the PVA component by hydrolysis but some thereof is made to remain by the hydrolysis reaction. The vinyl acetate component is, therefore, preferably low and in this sense, the copolymer consisting of 85 to 92wt.% vinyl chloride, 6 to 13wt.% PVA and 0 to 3wt.% 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 C. OBJECTS 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 various 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)
A resin material having film-forming ability such as nitrocellulose or a copolymer of vinyl chloride and vinyl acetate, (2)
Plasticizing effects on film-forming materials, such as light-shielding dyes and pigments, (3) low molecular weight plasticizers such as dibutyl phthalate and dioctyl phthalate, or high molecular weight plasticizers such as epoxy, polyester, or nitrile rubber. (4) Applying a coating agent containing a solvent or the like as a constituent component to a synthetic resin film base such as a polyester film directly or via an adhesive layer (pressure-sensitive adhesive layer) and drying it. 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 around the area with a knife cutter, or use an X connected 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 force of the releasable coating to the film support is determined by the workability (hereinafter referred to as repellency) when one end of the coating surrounded by the cut line is flicked off with the edge of a knife, etc. 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 the adhesion to the support will be poor; if the amount added is large, the adhesion will increase, but the film will be soft and stretchable, and will not block. will arise.

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 and cut-up properties as well as the 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 is characterized in that a specific vinyl chloride/vinyl alcohol/vinyl acetate copolymer has excellent performance in both physical properties and adhesion, which are particularly required as a releasable coating for a peelable masking film. It has been discovered that the adhesion force can be adjusted independently without affecting the film properties, and the present invention provides a peelable masking film with excellent properties.

[Structure of the Invention] (Means for Solving the Problems) To summarize the present invention, the present invention provides a peelable masking film in which a light-shielding peelable film is formed on a synthetic resin film support. The film-forming material constituting the peelable film is vinyl chloride......80-95% by weight vinyl alcohol...5-15% by weight vinyl acetate... This invention relates to a peelable masking film characterized by containing 0 to 5% by weight of a copolymer as a main component.

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

The most important 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 balanced physical properties in the above-mentioned film physical properties and adhesion, which are particularly required for a peelable coating of a peelable masking film, 80 to 95% by weight of vinyl chloride and 5 to 15% by weight of vinyl alcohol are used. , a copolymer consisting of 0 to 5% by weight of vinyl acetate is used.

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 5-20% by weight, 9 weight average degree of polymerization 200-800) 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 to approximately 10%. Dissolved at a concentration of 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. In the present invention,
It is desirable that the vinyl acetate component be as low as possible, and in this sense, a copolymer consisting of 85 to 92% by weight of vinyl chloride, 6 to 13% by weight of vinyl alcohol, and 0 to 3% 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. In other words, it seems that the hydroxyl group content in the copolymer contributes to the adhesion to the support film, and as the content ratio of vinyl alcohol increases, the adhesion of the coating to the film improves, but by 15%. If the content exceeds 5%, it will be difficult to remove the 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 along with the supporting film, the scored lines will disappear. The peel layer will lift up along the .

On the other hand, even if the vinyl alcohol content is within the above range, vinyl chloride content exceeding 95% has poor solubility and it is difficult to prepare a practical coating solution. If the residual content exceeds 5%, the adhesion to the support film decreases, making it impossible to obtain a practical peel film.

Therefore, in the copolymer composition used in the present invention, it is necessary to sufficiently saponify the vinyl acetate in the raw resin so that the vinyl acetate content is 5% or less, preferably 3% or less.

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 copolymer; vinyl chloride, vinyl acetate, maleic acid copolymer; vinyl chloride, vinylidene chloride copolymer; polymethacrylate ester; acrylic, styrene copolymer. ; Styrene, butadiene, block copolymer: Any resin may be used as long as it is compatible with the above-mentioned copolymer resin of the present invention.

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

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, (bl 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 N light agent (a) mentioned above, Solvent Yellow 33 (C1,47000), Solvent Red 18
f(:1.2L260), Solvent Brown 5 (C
T12020), Solvent Green 3 (CL615
Oil-soluble dyes that block ultraviolet rays, such as 65), or organic pigments, such as quinacridone, perylene red, disazo yellow, and disazo orange, are used.

The above-mentioned (b) plasticizers include dioctyl phthalate, tricresyl phosphate, polyethylene glycol dibasic acid esters, epoxidized vegetable oil, chlorinated paraffin, nitrile rubber, etc. It can be blended without damaging the

The roughening agent (C) mentioned above has a particle size of 0.3 to 1.
Inorganic fine powder such as silica, 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.

The FDL organic solvent mentioned above is acetone.

Ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and ester solvents such as methyl acetate, ethyl acetate, and butyl acetate are used alone or in combination, and aromatic solvents such as benzene, toluene, and xylene are used. Group solvents can also be incorporated as diluents.

The peelable film-forming material (paint) of the present invention comprising the above-mentioned components is applied to the base film support by a desired coating method to a desired thickness, for example, a dry thickness of 20 to 25 μm, and is dried to form a peelable film. A film is formed.

(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) Using three types of commercially available vinyl chloride/vinyl acetate copolymer resins (A, D, H) with different compositions as raw materials, six types of vinyl chloride, vinyl acetate, and vinyl acetate copolymer resins with different vinyl alcohol contents were obtained by hydrolyzing them.
Vinyl alcohol binary copolymer (B, C, E, F, G,
I) was prepared (see Table 2).

Next, a paint having the composition shown in Table 1 was prepared and applied to one side of an axially stretched polyethylene terephthalate film with a thickness of 100 microns using a variable gap applicator to a dry thickness of 23 microns, and heated at 120°C. A peel film was prepared by drying for 5 minutes in a constant temperature bath.

Characteristics of each sample as a peel film
) Thin wire stability 2) Lifting of the film 3) Splashability 4) CAD characteristics 5) Peeling resistance 6) Film strength 7)
Comprehensive evaluation was performed by comparing from the viewpoint of film elongation.

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 a sample with a width of 1 cm and a length of 20 cm by about 12 cm, and then using a tensile testing machine (manufactured by Naji Seisakusho, Autograph AG) to separate 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.

The film strength was determined by making a detachable piece with a width of 1 cm and a length of 15 cm, and setting it in a tensile tester 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.

Table 1 (Paint composition) (Unit double placement part) *Krayton D11.22, manufactured by Shell Chemical ■. Styrene/butadiene ratio 37/63 l 8 From Table 2, the peelable masking film of the present invention (C
, F, G) are superior.

(Example 2) The following commercially available vinyl chloride (VC)/vinyl alcohol (VO
II) ・Two types of vinyl acetate (VAC:) copolymer resins (
J, K) was used as the main component.

Example 1 was carried out using the following L) vinyl chloride/vinyl acetate copolymer resin, M) nitrile rubber, N) dioctyl phthalate instead of the block polymer shown in Table 1 as the additive component.
Peel film samples were prepared using the method described above, and their properties were evaluated.

Additive N) Manufactured by Daihe Kagaku Kogyo Co., Ltd., purity 99% or higher. Both samples showed good peeling properties. It should be noted that the addition of PVC/PVC resin slightly improved the hardness of the film, lowered the elongation rate of the film, and slightly lowered the peel resistance. Also,
Addition of nitrile rubber slightly increased the elongation of the film, and addition of dioctyl phthalate increased the elongation and softness of the film.

[Effects of the Invention] According to the present invention, the peelable coating of the peelable masking film is composed of a specific vinyl alcohol-containing vinyl chloride/vinyl acetate copolymer resin.

As a result, when removing (peeling) a peelable masking film, both the various film physical properties and adhesion strength, which are particularly required as characteristics of a peelable film, are ensured in a well-balanced manner, making the peeling (peeling) work more efficient. Yo (can be done.

Nitrile content 41%

Claims (1)

[Claims] 1. A peelable masking film formed by forming a light-shielding peelable film on a synthetic resin film support,
The film forming material constituting the peelable film is vinyl chloride...80 to 95% by weight
Vinyl alcohol: 5 to 15% by weight Vinyl acetate: 0 to 5% by weight of a copolymer. Peelable masking film. 2. The peelable masking film according to claim 1, wherein the synthetic resin film support is a biaxially stretched polyester film. 3. 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: 6 to 13% by weight vinyl acetate, 0 to 3% by weight. 4. 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 3, wherein the peelable masking film has a molecular weight of 800 to 800.