JPH01187564A - Light shieldable masking film - Google Patents

Abstract

PURPOSE:To provide good light resistance and to obviate generation of the bleeding problem of a light shielding agent by using hyperfine particles of a metal compd. as the light shielding agent into a light shieldable release layer. CONSTITUTION:The hyperfine particles of the UV absorptive metal compd. having <=250Angstrom grain size are incorporated as the light shielding agent into the light shieldable release layer. Iron oxides such as Fe2O3 and Fe3O4 are preferably used as the metal compd. The surfaces thereof are preferably coated by silicone oil or surfactant in order to improve dispersibility. The ratio of using the hyperfine particles of the metal compd. is 2-20wt.%, more preferably 2.5-15wt.% in the light shieldable release layer. The light shielding effect is additionally enhanced by combination use of a yellow dye. The light shieldable masking film having the light shieldable release layer which has the excellent light resistance and does not bleed the light shielding agent is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a light-shielding masking film suitable for use in the printing plate-making field.

[Prior art]

Conventionally, as a light-shielding masking film used in the above-mentioned field, one in which a light-shielding and removable layer (light-shielding peeling layer) is formed on one side of a support made of a plastic film is known. In this case, the light-shielding release layer is formed by applying a coating composition in which a light-shielding agent is mixed with a polymeric substance onto a plastic film and drying it.

It is also known to form a pressure-sensitive adhesive layer between a support and a light-shielding release layer so that the light-shielding release layer can be reattached to the support after being peeled off.

Incidentally, as a light-shielding agent in such a light-shielding release layer, an oil-soluble dye that is soluble in an organic solvent is usually used. However, since such dyes are organic compounds, they have poor light resistance.Secondly, in order to obtain sufficient light-shielding properties for practical use, it is necessary to add a large amount, which deteriorates the performance of the light-shielding release layer film. However, there was also the drawback that the dye used as a light-shielding agent bleed onto the surface of the film.

〔the purpose〕

The present invention overcomes the above-mentioned drawbacks found in the prior art, and provides excellent light resistance and light-shielding peeling without bleeding of the light-shielding agent.
An object of the present invention is to provide a light-shielding masking film having the following properties.

〔composition〕

According to the present invention, in a light-shielding masking film having a light-shielding release layer on a support, fine particles of an ultraviolet-absorbing metal compound having a particle size of 250 Å or less are contained as a light-shielding agent in the light-shielding release layer. A light-shielding masking film 11 is provided.

First, the support constituting the light-shielding masking film of the present invention includes polyesters such as polyethylene terephthalate and polybutylene terephthalate, aliphatic or aromatic polyamides, polyolefins such as polyethylene and polypropylene, polystyrene, polycarbonate, polyvinyl chloride, and polyester. Synthetic resin film made of vinylidene chloride etc., semi-synthetic resin film such as cellulose acetate 1, etc., synthetic resin film 11 containing synthetic resin film 11
and semi-synthetic resin film, furthermore, synthetic resin film 11
and/or a laminate film of a semi-synthetic resin film and paper.

This support is preferably colorless and transparent.

Among the above, polyethylene terephthalate film is
It is particularly preferred because it has high tensile and tear strength and excellent dimensional stability. The support has a thickness of 50
~250 μm is preferable. The film constituting the support may be either stretched or non-stretched from the viewpoint of its manufacturing method.

Next, the composition for forming the light-shielding peeling layer, which is the greatest feature of the present invention, will be described in detail.

First, as the release layer forming organic polymer compound, for example,
Polyvinyl chloride; Polyvinylidene chloride; Polyvinyl acetate; Polyvinyl formal; Polyvinyl acetal such as polyvinyl butyral; Acrylic resin; Polyamide resin;
Polyacetal resin; polyester resin; phenolic resin; urea resin, melamine resin; alkyd resin; polyurethane resin; acetic acid fiber resin; polyvinyl alcohol;
Copolymers mainly composed of vinyl chloride, such as vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylic acid ester copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer Coalescence: copolymers mainly composed of hinyl acetate, such as vinyl acetate-ethylene copolymers; celluloses such as nitrocellulose, acetylcellulose, alkylcellulose, and acetylalkylcellulose; diene rubbers such as acrylonitrile-butadiene rubber; acrylic rubber, etc. Examples include olefin rubber; urethane rubber, etc.

All of the above are examples, and it goes without saying that the organic polymer compound of the present invention is not limited to them.

When using the above-mentioned compounds, not only one type but also two types can be used.
It is preferable to use one or more species in combination.

In the present invention, among the above, vinyl chloride-vinylidene chloride copolymer and diene rubber or vinyl chloride-vinyl acetate copolymer and diene rubber are preferably used together, and more preferably vinyl chloride-vinylidene chloride copolymer and diene rubber. It is preferable to use the copolymer and nitrile rubber (acrylonitrile-butadiene rubber) in combination.

A light-shielding release layer using a combination of a vinyl chloride-acetic acid quasi-vinyl copolymer and a nitrile rubber 4- rubber has the following drawbacks, but a combination of a vinyl chloride-vinylidene chloride copolymer and a nitrile rubber 11 When using , these difficulties can be overcome.

(1) The adhesion force to the support is too strong, making it difficult to work, especially when peeling off a large area. For this reason, specifically, the following problems arise.

■The film to be peeled and removed may stretch abnormally or break during peeling, making the work time-consuming.

■It is difficult to lift the edge of the cut coating film with the tip of the blade, grab the coating film with your fingertips, and peel it off because the adhesive is too strong.

(2) Poor springiness. For this reason, it is difficult to lift (spring) the edge of the cut coating film with the cutting edge.

(3) Changes in temperature and humidity affect release characteristics, making it difficult to maintain constant release characteristics.

In the present invention, when a vinyl chloride-vinylidene chloride copolymer is used as the polymer compound in the composition of the light-shielding release layer, the copolymerization ratio is 60 to 95% vinyl chloride.
Weight X, preferably 70-90% by weight, vinylidene chloride 40-5% by weight, preferably 30-10% by weight.

If the proportion of vinylidene chloride is too high, the coating film will become sticky, while if it is too small, the coating film will become hard and prone to cracking when peeled off. Also, vinyl chloride-
The average degree of polymerization of vinylidene chloride copolymer is 300 to 60
0, preferably in the range of 400-500. If the degree of polymerization is too high, the solubility will be poor, so it will take time to prepare the coating liquid, and the viscosity will be high, making uniform coating difficult. If the degree of polymerization is too low, the coating film will easily crack when peeled off.

Next, as the nitrile rubber, one whose main components are butadiene and acrylonitrile is used.

Examples of such resins include acrylonitrile-butadiene rubber, an acrylonitrile-butadiene copolymer, and a terpolymer resin containing a monomer containing a carboxyl group. In the present invention, the acrylonitrile content is 18 to 53% by weight, preferably 25 to 43% by weight.
It is preferable that the amount is within the range of % by weight.

When using vinyl chloride-vinylidene chloride copolymer and nitrile rubber together as organic polymer compounds, vinyl chloride-vinylidene chloride copolymer and nitrile rubber are used together.
Usage ratio of vinylidene chloride copolymer and nitrile rubber (
Weight ratio) is 50150 to 9575, preferably 60/
40-90/10 is good. If the amount of vinyl chloride-vinylidene chloride copolymer used is too small, the coating film will become soft.
The repellency will be poor and the adhesion to the support will be too strong. Moreover, if they are placed one on top of the other, they tend to form a block shape. Furthermore, the coating film to be removed tends to stretch, making removal work difficult. On the other hand, if the amount is too large, the adhesion to the support becomes weak and the coating film that is peeled off becomes easily cracked.

In the present invention, as a light shielding agent, the average particle size is 250 Å.
The following fine particles of metal compounds are used. In this case, as the metal compound, one having ultraviolet absorbing properties is used, and for example, iron oxides such as Fe, 03, and Fe3O4 are preferably used. The finer particles the metal compound is, the more preferable it is, and the average particle size is 250 Å or less, preferably 1
It is preferable to set the thickness to 00 Å or less.

Further, in order to improve the dispersibility of the metal compound-derived fine particles, it is preferable to coat the surface with silicone oil or a surfactant. The proportion of the metal compound-derived fine particles used in the present invention is 2 to 20% by weight, preferably 2.5 to 15% by weight, during light-shielding peeling.

The metal compound-derived fine particles used in the present invention are preferably used in combination with a yellow dye. By using this yellow dye in combination, the light-shielding effect can be further enhanced. In this case, the amount of the dye added may be small, usually 1 to 1 in the light-shielding release layer.
0% by weight, preferably about 2 to 6% by weight is sufficient.

By using such a small amount of yellow dye in combination, light with a wavelength of 500 nm or less can be almost completely blocked.

The light-shielding release layer in the present invention may further contain a filler, if necessary.

In this case, as the filler, an inorganic filler such as silica can be used, but it is preferable to use an organic filler. Examples of organic fillers include crosslinked polystyrene, benzoguanamine-formaldehyde condensate, nylon (6,6
- nylon, 6-nylon, 12-nylon, etc.), silicone resin, crystalline cellulose, phenol-formaldehyde resin, fluororesin, polyethylene resin, acrylic resin, etc. Among these, polystyrene beads have excellent dispersibility when preparing a light-shielding coating composition, the resulting light-shielding release layer adheres to the support with appropriate adhesive strength, and the surface also has a light-reflection-preventing property. It is particularly suitable because it has characteristics such as being easy to see and not causing blocking even when laminated. The particle size of the filler is 0.5-20 μm, preferably 2-15 μm.

The masking film of the present invention can be obtained by uniformly applying a composition comprising the above-mentioned components to one side of a support by any method.

The thickness of the light-shielding peeling layer is usually 10 to 50 ILm, preferably 20 to 40 μm.

At this time, if necessary, a suitable organic solvent such as an alcohol-based, ester-based, hydrocarbon-based,/) rogenated hydrocarbon-based, or ketone-based solvent can be used.

Furthermore, there is no problem in adding a leveling agent, an antiblocking agent, a plasticizer, etc. to the composition as long as they do not impede the object of the present invention.

In the present invention, a pressure-sensitive adhesive layer may be provided on the support, and a light-shielding peeling layer may be provided thereon. There are no particular restrictions on the adhesive that can be used at this time, and synthetic resin-based and rubber-based adhesives can be used. Such a configuration is useful because it can be suitably used when the peeled film is reused (re-attached).

〔effect〕

Since the light-shielding masking film of the present invention uses fine particles of a metal compound as the light-shielding agent in its light-shielding release layer, it has better light resistance than conventional ones and also has the problem of bleeding of the light-shielding agent. does not occur. Further, the amount added may be a small amount, usually 10 weight or less, in the light-shielding release layer, and does not particularly impair the transparency and film performance of the light-shielding release layer.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

A coating solution having the component composition (parts by weight) shown in Example Table 1 was prepared, and this was coated onto a polyester film as a support and dried to form a photosensitive release M (film thickness: 40 μm).

Next, the optical density of the thus obtained light-shielding masking film against light in the ultraviolet and visible regions was measured to evaluate its transparency and light-shielding properties, and the results are shown in Table 2. In this case, the optical density is expressed by the following formula, and the larger the value, the better the light shielding property.

D = -QogT (In the formula, T is light transmittance 2) In addition, transparency and light blocking properties were evaluated using a five-step method,
A higher number indicates better quality.

Further, master liquids A, B, and C shown in Table 2 have the following component compositions (parts by weight).

Table-1 12 Sansosizer E-4030 (manufactured by New Japan Chemical) 9
3 Thyroid 74 (manufactured by Fuji Davison Chemical Co., Ltd.)
The properties of the light shielding agent shown in Table 2 are as follows.

Fe2O3...Fe2O3 particles whose surface is coated with a monomolecular film of calcium stearate (Fe203 content = 45-50 Juho 2, average particle size: 50 people) Fe304-
Average particle size: 200 Red Garlic (a) / Average particle size: 2100 Red Garlic (b)
)...Average particle size: 1500 people Dye/Oil-soluble yellow dye (Savinyl Yellow RLS) As can be seen from the results shown in Table 2, when red iron oxide with a large particle size was used as a light shielding agent (Experiment No. 4) .

In 5), the transparency is so poor that it is not practical, and the ultraviolet density is low and does not have a sufficient ultraviolet density for close contact reverse exposure to a silver salt film. On the other hand, in the case where a dye was used as a light-shielding agent (Experiment No. 8), bleeding of the dye onto the surface of the light-shielding release layer was observed.

On the other hand, in the case of the present invention (Experiment No. 2, 3, 6.
7) had sufficient ultraviolet density and transparency for practical use.

=15-

Claims (2)

[Claims] (1) In a light-shielding masking film having a light-shielding release layer on a support, fine particles of an ultraviolet-absorbing metal compound with an average particle size of 250 Å or less are contained as a light-shielding agent in the light-shielding release layer. A light-shielding masking film with special features. (2) The light-shielding masking film according to claim 1, wherein the light-shielding release layer contains a yellow dye.