JP3087333B2 - Cover film for photosensitive cured resin plate making - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas-permeable polypropylene resin film used as a cover film for plate making of a photosensitive cured resin.

[0002]

2. Description of the Related Art Instead of a conventional lead plate or rubber plate, a photosensitive cured resin plate in which an ultraviolet curable resin layer is partially formed on a plastic film serving as a support is used.

[0003] Plate making technology using this photosensitive resin is based on a base film (support) made of a polyester film or the like.
After the photosensitive resin layer in the uncured state uniformly formed thereon is irradiated with ultraviolet light through a negative film to partially cure the photosensitive resin layer, the photosensitive resin layer in the uncured portion is removed. By washing, resin plate making is performed, and in such a photosensitive cured resin plate making technique, the uncured photosensitive resin layer subjected to ultraviolet irradiation has a fluidity of ~
Since the photosensitive resin layer in an uncured state is in direct contact with the negative film because it is in an adhesive state, the negative film cannot be reused.

[0004] For this reason, in the step of irradiating the uncured photosensitive resin layer with ultraviolet light, a cover film is inserted between the uncured photosensitive resin layer and the negative film. The negative film can be used repeatedly. The cover film used at this time is required to have good properties in terms of transparency, peelability, solvent resistance and the like, and a stretched polypropylene resin film having these properties in combination is required. It is widely used as a cover film.

[0005]

Incidentally, the above-mentioned photosensitive resin which is cured by ultraviolet rays involves the generation of nitrogen gas in the curing step. Therefore, if the plastic film used as the cover film has low air permeability, it is removed. The air is not sufficient, and fine bubbles remain in the obtained cured resin layer. In particular, if these fine air bubbles remain in the cured resin layer of the printing plate making, this causes unclearness at the time of printing.

For this reason, when a stretched polypropylene resin film is used as a cover film for a photosensitive cured resin plate making, the thickness is set to 6 μm or less from the viewpoint of providing necessary air permeability to the cover film. It must be used in such a thin state. However, since the thickness is not sufficient as compared with a general plastic film, handling workability is remarkably deteriorated, wrinkles are easily generated, and efficient hardened resin plate making cannot be performed.

As a method for improving the air permeability of a polypropylene-based resin film, for example, an inorganic fine powder such as silica or calcium carbonate or a resin having poor compatibility with a polypropylene-based resin such as polyether is blended. A method of extruding a resin and then stretching and orienting the resin to form a porous film in which voids are formed in the thickness direction of the film is known, but a gas-permeable polypropylene resin film obtained by such a method is known. Is
The film is clouded due to a large number of voids generated in the film, and cannot be used as a cover film for a photosensitive cured resin plate making it necessary to transmit ultraviolet rays.

On the other hand, the present inventors utilize polybutene-1 resin as a mixed resin component for a polypropylene-based resin, thereby obtaining transparency and peeling required for a cover film for photosensitive hardened resin plate making. Biaxially stretched polypropylene resin film with high nitrogen gas permeability even if the film is of sufficient thickness to obtain good handling workability without sacrificing properties such as water resistance and solvent resistance Can be produced under stretching conditions on an industrial scale.

[0009]

The above objects can be attained by a cover film for plate making of a photosensitive cured resin of the present invention having the constitution described below. That is, the first invention comprises 100 parts by weight of a polypropylene resin and 5 parts by weight.
A single-layer film with a thickness of 9 μ or more made of a mixed resin with a polybutene-1 resin in an amount of at least 1 part by weight, stretched in the vertical and horizontal directions, and having a haze (%) of 6 or less according to JIS K 6718, Moreover, the nitrogen gas permeability is 1000ml
/ m ^{2 ・} 24hr ・ atm or more.

The second invention relates to a polypropylene resin 1
00 parts by weight, 5 parts by weight or more of polybutene-1 resin,
A single-layer film having a thickness of 9 μ or more made of a mixed resin of 10 parts by weight or less of a polyethylene resin with respect to 100 parts by weight of the total of the polypropylene-based resin and the polybutene-1 resin. And
The cover film for a photosensitive curable resin plate has a haze (%) of 6 or less according to JIS K 6718 and a nitrogen gas permeability of 1000 ml / m ^{2 ·} 24 hr · atm or more.

In the cover film for plate making of a photosensitive cured resin according to the present invention having the above-mentioned constitution, the polybutene-1 resin in the resin composition serves to enhance the air permeability of the obtained stretched film and can be used. Polybutene 1
There is no particular limitation on the degree of crystallinity of the resin. However, when the polybutene-1 resin is less than 5 parts by weight based on 100 parts by weight of the polypropylene resin in the resin component for film formation, the nitrogen gas permeability is not sufficiently improved even in the case of a stretched film having a thickness of 9 μm. There are cases. Also,
When the mixing amount of the polybutene-1 resin increases, the stretchability of the raw film deteriorates, and the resin adheres to a roll or adheres to a clip and breaks during a stretching process under stretching conditions on an industrial scale. Therefore, it is difficult to obtain a good stretched film. In addition, polybutene-1 which can be mixed
The maximum amount of the resin differs depending on the thickness of the stretched film as the target product. For example, when obtaining a stretched film having a thickness of about 15μ having extremely good properties in handling workability, 100 parts by weight of the polypropylene resin To about 400 parts by weight of polybutene-1 resin.

Further, when the stretched film made of a mixed resin of a polypropylene resin and a polybutene-1 resin is subjected to corona discharge treatment or the like to improve the adhesion between the stretched film and the photosensitive resin, blocking resistance is reduced. However, if low-density or high-density polyethylene is added to the film-forming resin to roughen the surface of the stretched film, the adhesion with the photosensitive resin is improved, and the blocking resistance is reduced. Can be suppressed. However, when the mixing amount of the polyethylene resin is less than 5% by weight of the total amount of the polypropylene resin and the polybutene / 1, the above-described effect of preventing the decrease in the anti-blocking property is not sufficient, and also exceeds 10% by weight. As a result, the ultraviolet transmittance of the obtained stretched film decreases.

Therefore, the polyethylene resin added for the purpose of increasing the blocking resistance is 1 part by weight based on 100 parts by weight of the total of the polypropylene resin and the polybutene-1.
It can be suppressed to 0 parts by weight or less.

Further, by adding an inorganic fine powder such as silica to the above-mentioned resin component in the film forming raw material,
Although the blocking resistance of the obtained stretched film can be increased, the addition of such an inorganic fine powder is a factor that generates voids in the stretched film and this leads to a decrease in transparency. Addition must be kept to a minimum.

[0015]

EXAMPLES The specific structure of the cover film for plate-forming a photosensitive cured resin of the present invention will be described below with reference to production examples.

Examples 1-14, Comparative Examples 1-2 Isotactic polypropylene homopolymer (MFR
(1.8 g / 10 min) and polybutene-1 resin were mixed at a ratio described in the predetermined column of [Table 1], and extruded at 260 ° C. to obtain a raw material. By a tenter stretching method, a longitudinal stretching at 140 ° C. followed by 140 ° C.
To 160 ° C. in the transverse direction, and a cover film (1) for a photosensitive cured resin plate making, which is an example of the present invention.
(14) and polypropylene resin film for comparison
(a) and (b) were obtained.

The thickness (μ) of each polypropylene resin film, nitrogen gas permeability at normal temperature (ml / m ² · 24 hr · atm),
The haze (%) and the degree of blocking (grade) according to JIS K 6718 are shown in [Table 2].

The nitrogen gas permeability (ml / m ² · 24 hr · atm)
Is an Analytic Gas Permeabili
ty Measured by FRCTOMETER GPM-250. The degree of blocking (class) is measured by placing a 2 kg weight on top of the same two films and leaving them in an atmosphere of 40 ° C. and 70% RH for 24 hours. Based on the above operation, Grade 1 ..... Peel off without resistance when lightly peeled off with fingertips Grade 2 ........ There is some resistance when peeled off lightly with fingertips, but peels off 3 Grade ..... It is quite resistant when peeled lightly with fingertips, but peels off Grade 4 ...
Films that have been strongly peeled off with the fingertips are slippery between the superimposed surfaces. Grade 5 ... The film that has been strongly peeled off with the fingertips is not peeled off when the film is lightly peeled off with the fingertips. Judged by not slipping.

[0019]

[Table 1]

[0020]

[Table 2]

Examples 15 to 29, Comparative Example 3 Isotactic polypropylene homopolymer (MFR
(1.8 g / 10 min), polybutene-1 resin and high-density polyethylene resin were mixed at a ratio described in the prescribed column of [Table 3]. This raw material was subjected to a longitudinal stretching at 140 ° C. and subsequently to a transverse stretching at 140 to 160 ° C. by a tenter stretching method for a photosensitive cured resin plate which is an example of the present invention. (15) to (29) and a polypropylene resin film (c) for comparison.

The thickness (μ) of each polypropylene resin film, nitrogen gas permeability (ml / m ² · 24 hr · atm), JIS K 67
The results of measuring the haze (%) and the degree of blocking (grade) according to 18 in the same manner as described above are shown in [Table 4].

[0023]

[Table 3]

[0024]

[Table 4]

Comparative Examples 4 to 8 Isotactic polypropylene homopolymer (MFR
(1.8 g / 10 min) was extruded at 260 ° C. to obtain a raw material, and the raw material was stretched by a tenter stretching method in the longitudinal direction at 140 ° C. and subsequently in the transverse direction at 140 to 160 ° C. To obtain polypropylene resin films (d) to (h) having different thicknesses for comparison.

The thickness (μ) of each polypropylene resin film, nitrogen gas permeability (ml / m ² · 24 hr · atm), JIS K 67
The results of measuring the haze (%) and the degree of blocking (grade) according to 18 in the same manner as described above are shown in [Table 5].

[0027]

[Table 5]

[0028]

The cover film for plate making of the photosensitive curable resin of the present invention is produced by using a polybutene / 1 resin as a mixed resin with a polypropylene resin and under stretching conditions on an industrial scale. As a result, the air permeability of the polybutene / 1 resin, which is a mixed resin component, can be obtained without sacrificing any properties required for the cover film of the photosensitive resin plate making system, such as transparency, peelability, and solvent resistance. A cover film for a photosensitive cured resin plate even if it has a sufficient thickness with good handling workability and does not easily generate wrinkles, specifically, a thickness of 9 μ or more. It has a nitrogen gas permeability necessary for the above.

Therefore, the cover film for the photosensitive cured resin plate making of the present invention is required for the cover film of the photosensitive cured resin plate making system to have transparency, peelability, solvent resistance, nitrogen gas permeability and the like. Has good properties and also has good workability. By using this cover film, a high quality photosensitive cured resin plate can be obtained.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FIB29L 7:00 (56) References JP-A-50-113551 (JP, A) JP-A-63-199742 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) G03F 7/11 501 B29C 55/00-55/30 B29D 7/00-7/01 C08J 9/00-9/42 C08J 5/00-5 / 24 C08L 1/00-101/16

Claims (2)

(57) [Claims] 1. 100 parts by weight of a polypropylene resin and 5 parts by weight
A cover film for a photosensitive hardened resin plate made of a single-layer film having a thickness of 9 μ or more made of a mixed resin of a polybutene / 1 resin and a JIS K Haze (%) by 6718 is 6 or less, and nitrogen gas permeability is 1000 ml / m ^{2 ·} 24 hr
-A cover film for photosensitive hardened resin plate making, characterized by being atm or more. 2. 100 parts by weight of a polypropylene resin,
From a single-layer film having a thickness of 9 μ or more made of a mixed resin of 5 parts by weight or more of polybutene-1 resin and 10 parts by weight or less of polyethylene resin with respect to a total of 100 parts by weight of the polypropylene-based resin and polybutene-1 resin. A cover film for making a photosensitive cured resin plate, which is stretched in the vertical and horizontal directions, has a haze (%) of 6 or less according to JIS K 6718, and has a nitrogen gas permeability of 1000.
A cover film for plate making of a photosensitive cured resin, wherein the cover film has a ml / m ^{2 ·} 24 hr · atm or more.