JPH07149936A - Opaque stretched resin film - Google Patents

Abstract

PURPOSE:To obtain the film free from uneven whitening and paper dust trouble and excellent in hiding power by stretching a film comprising a propylene resin, an arom. polycarbonate resin, and a styrene-grafted propylene resin in such a manner as to obtain specified porosity and opaqueness. CONSTITUTION:This film is produced by stretching a film formed from a thermoplastic resin compsn. comprising 50-94wt.% propylene resin, 49-5wt.% arom. polycarbonate resin, and 0.1-7wt.% styrene-grafted propylene resin in such a manner as to obtain a porosity determined by the formula of 20-70% and an opaqueness of 75% or higher. The resin compsn. is melt mixed on an extruder at above the m.p. of the propylene resin (e.g. 200-300 deg.C) to disperse fine particles of the arom. polycarbonate resin in the propylene resin, is extruded through a die into a film, and stretched at least monoaxially to a stretching ratio of 3.5-12 at a temp. suitable to obtain the desired porosity (e.g. 130-140 deg.C).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an opaque stretched resin film having fine pores inside. This opaque resin stretched film is useful as a support for outdoor poster paper, label paper, drawing paper, sticker paper and the like, as well as bar code paper, photographic paper, thermal recording paper and thermal transfer image receiving paper.

[0002]

2. Description of the Related Art Synthetic paper obtained by drawing a thermoplastic resin film containing inorganic fine powder and having fine pores inside the film has water resistance, strength, smoothness, etc. in comparison with pulp paper. It is used as a support for election poster paper, label paper, heat-sensitive recording paper and thermal transfer image receiving paper, etc. (Japanese Patent Publication No. 46-40794, Japanese Patent Publication No.
60-36173, Japanese Patent Publication No. 54-31032, U.S. Patent 3773608
No. 4917719). Synthetic paper using these inorganic fine powders as a pore-generating agent by stretching the film has fine pores centered on the inorganic fine powder inside the resin stretched film, and also from the surface of the resin stretched film. Some inorganic fine powders protrude and secondary aggregates of these inorganic fine powders (Japanese Patent Laid-Open No. 62-87390) are also present, so that they fall off from the surface of the synthetic paper during printing, causing white spots (so-called pinholes). Hall trouble) There is a drawback. This blanking is conspicuous and becomes a problem particularly when solid printing / printing in which printing / printing is black. In addition, the inorganic fine powder that has fallen off the surface of the synthetic paper during offset printing mixes into the ink through the blanket, causing the fluidity of the ink to be lost and preventing the proper transfer of the ink from the printing machine to the printing paper. However, there is a problem that the finish of the printed matter is deteriorated (so-called paper dust trouble). As such a synthetic paper with less paper dust trouble, a film matrix resin and a film having a higher melting point than the melting point of the matrix resin and a mixture with a thermoplastic resin that is incompatible with the matrix are stretched. , A synthetic paper having a satin-like appearance composed of a stretched resin film using the high melting point resin as a pore-generating agent has been proposed (US Pat. No. 3154461, US Pat. No. 4438715, US Pat. 59-209849, Special Fairness 3-
24334 publication). Specifically, these use polypropylene as the matrix of the stretched film, polyethylene terephthalate as the high melting point resin of the pore generating agent,
Polybutylene terephthalate or nylon 6 is used.

[0003]

When the pore generating agent is nylon 6, the dispersibility in the polypropylene matrix is poor, the particle size of the nylon 6 particles is as large as 8 to 10 μm, and the pores formed are coarse. Therefore, peko (wrinkles caused by buckling when the stretched film is bent) is likely to occur, and there is a problem in practical use. When polyethylene terephthalate or polybutylene terephthalate is used as a pore generating agent, the generation of pores is small and only synthetic paper having an opacity of 70% or less can be obtained. In order to increase the opacity of the synthetic paper obtained by increasing the generation of pores, if the stretching temperature is lower than the optimum stretching temperature of polypropylene, the resin film may be broken during stretching, or the chuck of a stretch tenter (of the stretched film). The film may come off from the holder and the production efficiency decreases. When a propylene copolymer resin such as an ethylene / propylene random copolymer having a lower melting point than that of a propylene homocopolymer is used to obtain stretching stability, white spots occur. It is an object of the present invention to provide a synthetic paper having high opacity and free from white spots and paper dust trouble.

[0004]

DISCLOSURE OF THE INVENTION According to the present invention, 50 to 94% by weight of a propylene resin and 4 aromatic polycarbonate resins are used.
A resin stretched film based on a thermoplastic resin containing 9 to 5% by weight and 0.1 to 5% by weight of a styrene-grafted propylene-based resin, the stretched resin film comprising:
The following formula

[0005]

[Equation 2]

The present invention provides an opaque resin stretched film having pores having a porosity of 20 to 70% calculated in (1) and having an opacity of 75% or more.

Further, the MFR of the propylene resin is 0.3 to
50 g / 10 minutes, 50 to 94% by weight of ethylene / propylene random copolymer having an ethylene content of 0.5 to 8% by weight, 49 to 5% by weight of aromatic polycarbonate resin and 0.1 to 7% by weight of styrene-grafted propylene resin. % Of a thermoplastic resin as a base material, and the resin stretched film has a porosity of 20 to 70%.
And an opacity of 75% or more.

[0008]

[Detailed Description of the Invention]

(Propylene-based resin) As the propylene-based resin, propylene homopolymer, propylene, ethylene, butene-
Copolymers with α-olefins such as 1, hexene-1, heptene-1, and 4-methylpentene-1 are used. This copolymer may be a random copolymer or a block copolymer. Preferably, the melt flow rate (J
IS K-7210; 230 ° C., 2.16 kg load) is preferably 0.3 to 50 g / 10 minutes and the melting point is 130 to 190 ° C. In particular, ethylene-propylene random copolymers having an ethylene content of 0.5 to 8% by weight, ethylene-propylene-butene-1 (3 to 12% by weight) random copolymers and the like having a melting point of 140 to 160 ° C. Stretching is easy when a copolymer is used. Further, a blend of copolymers (MFR of 0.3 to 5 g / 10 minutes, ethylene content of 0.5 to 8% by weight of ethylene / propylene random copolymer 45 to 70% by weight, MFR of 3 to 50 g / min. 10
The ethylene / propylene random copolymer having an ethylene content of 0.5 to 8% by weight and having an MFR greater than the MFR of the ethylene / propylene random copolymer by 2 g / 10 minutes or more. A resin stretched film based on a thermoplastic resin containing 5 to 50% by weight of a polymer, 49 to 5% by weight of an aromatic polycarbonate resin and 0.1 to 7% by weight of a styrene-grafted propylene-based resin, the resin comprising: Stretched film
Porosity of 20-70% and opacity of 75%
Opaque resin stretched film characterized by the above)
Is more preferable.

(Aromatic Polycarbonate Resin) The aromatic polycarbonate resin (A) comprises an aromatic dihydroxy compound or a small amount of this compound and an aliphatic polyhydroxy compound.
It is produced by reacting with phosgene. Also,
It is also produced by transesterifying an aromatic dihydroxy compound or a small amount of an aliphatic polyhydroxy compound with a carbonic acid diester. If necessary, a trifunctional compound as a branching agent and a molecular weight modifier are also provided for the reaction. This aromatic polycarbonate resin is a thermoplastic aromatic polycarbonate which may be branched or unbranched.

As the aromatic dihydroxy compound, 2,
2-bis (4-hydroxyphenyl) propane (hereinafter abbreviated as bisphenol A), tetraphenylbisphenol A, tetrabromobisphenol A, bis (4-
Hydroxyphenyl) -p-isopropylbenzene, hydroquinone, resorcinol, 4,4′-hydroxyphenyl, bis (4-hydroxyphenyl) methane, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) sulfone, bis ( 4-hydroxyphenyl) sulfoxide, bis (4-hydroxyphenyl)
Sulfide, bis (4-hydroxyphenyl) ketone,
Examples thereof include 1,1-bis (4-hydroxyphenyl) ethane and bis (4-hydroxyphenyl) cyclohexanone, and bisphenol A is particularly preferable.

Further, in order to obtain a branched aromatic polycarbonate resin, phloroglucin, 4,6-dimethyl-
2,4,6-tri (4-hydroxyphenyl) heptene-2,4,6-dimethyl-2,4,6-tri (4-hydroxyphenyl) heptane, 2,6-dimethyl-2,
4,6-Tri (4-hydroxyphenyl) heptene-
3,2,6-dimethyl-2,4,6-tri (4-hydroxyphenyl) heptane, 1,3,5-tri (4-hydroxyphenyl) benzene, 1,1,1-tri (4-hydroxyphenyl) ) Polyhydroxy compounds exemplified by ethane and the like, and 3,3-bis (4-hydroxyaryl) oxindole [= isatin (bisphenol A)], 5-chloroisatin, 5,7-dichloroisatin, 5-bromoisatin, etc. Is replaced with a part of the dihydroxy compound, for example, 0.1 to 2 mol% by the polyhydroxy compound.

Further suitable monohydric hydroxy compounds for controlling the molecular weight are m- and p-methylphenol,
Examples include m- and p-propylphenol, p-bromophenol, p-tertiary-butylphenol, and p-long chain alkyl-substituted phenol. A preferred aromatic polycarbonate resin is a bis (4-hydroxyphenyl) alkane-based compound, particularly preferably a polycarbonate containing bisphenol A as a main raw material. A branched polycarbonate obtained by using two or more kinds of aromatic dihydroxy compounds in combination can also be mentioned as a preferable example (JP-A-63-3).
No. 0524, No. 56-52338, No. 55-414, No. 60-25049
No. 3, Japanese Patent Publication No. 3-49930). The aromatic polycarbonate resin may be used as a mixture of two or more kinds.

(Compatibilizer) A method for producing a styrene-grafted propylene-based resin suitable as a compatibilizer for compatibilizing an aromatic polycarbonate resin and a propylene-based resin is, for example, 100 parts by weight of polypropylene resin particles and 50 parts of a styrene monomer.
To 400 parts by weight and a radical polymerization initiator with respect to 100 parts by weight of the styrene monomer, 0.01 to 1 part by weight of an aqueous suspension is heated to polymerize the styrene monomer to obtain styrene-grafted polypropylene resin particles. (Japanese Patent Publication No. 63-31503, JP-A-49-5473,
50-129765, 50-32990, 52-50389, 52-50
(See Japanese Patent No. 390). As the radical initiator, cyclohexanone peroxide, t-butyl peroxybenzoate, methyl ethyl ketone peroxide, dicumyl peroxide, di-t-butyl peroxide,
2,5-dimethyl-2,5-dibenzoylperoxyhexane, di-t-butyl-di-peroxyphthalate and the like can be mentioned. The polymerization temperature is 80 to 150 ° C, preferably 100 to 130 ° C.

(Optional component) The film-forming resin composition may contain a stabilizer, an ultraviolet absorber and a dispersant.
If necessary, 30% by weight or less of the resin component may be replaced with high density polyethylene, linear low density polyethylene, nylon 6, nylon 6,6, or polyethylene terephthalate.

In the present invention, when the propylene-based resin is less than 50% by weight in the substrate, the stretchability is poor, and when it is 94% by weight or more, the amount of voids is small and the opacity is poor.
Further, when the polycarbonate exceeds 50% by weight, there is a problem that the stretchability is poor, and when it is less than 7% by weight, the amount of voids generated is small and the opacity is lacking. Further, if the styrene-grafted propylene-based resin is less than 0.1% by weight, the compatibility between the propylene-based resin and the polycarbonate is poor and only a stretched film with many white spots can be obtained. On the other hand, if it exceeds 7% by weight, the amount of voids generated is small and the opacity is poor.

(Production of Stretched Film) The stretched film of the present invention comprises a resin composition containing a propylene-based resin, an aromatic polycarbonate and a styrene-grafted propylene-based resin at a temperature exceeding the melting point of the propylene-based resin using an extruder. Aromatic polycarbonate fine powder (preferably 0.1 to 3 μm) is dispersed in propylene-based resin by melt-kneading at 200 to 300 ° C. and extruded into a film form from a die, and then the film is cut into desired voids. The temperature at which porosity is obtained (for example, 130 ° C to 140 ° C).
At 3.5 ° C in at least one direction, preferably 3.5 to 5.5 times in the extruding direction (MD), in the width direction (TD).
It is obtained by stretching 4 to 12 times. If necessary, the stretched film of the present invention may be laminated with another resin film or pulp paper. Other resins for films include
Olefin resin such as ethylene resin and propylene resin, saturated polyester resin such as polyethylene terephthalate and polybutylene terephthalate, nylon 6,
Examples thereof include polyamide resins such as nylon 6,6, polyvinyl chloride, polystyrene and the like. These resins are
Fillers such as calcium carbonate, titanium dioxide, clay and barium sulfate may be included.

(Stretched Film) This stretched film has a porosity of 20 to 70%, preferably 25 to 60%, and an opacity (JIS P-8138) of 75% or more, preferably 80 to 100%. is there. When the porosity is less than 20%, diffuse reflection of light is insufficient and a paper-like feel cannot be obtained. Further, if it exceeds 70%, the strength of the synthetic paper becomes brittle.
If the opacity is less than 75%, the covertness is insufficient, and when printing and binding on this, the print of the next page can be seen through, or in the case of double-sided printing, the back side of the print looks dull, The print / printed surface on the surface becomes difficult to see. This stretched film itself is used as a poster paper, a drafting paper, or by providing a gelatin layer, a heat-sensitive recording coating layer, an image-receiving recording layer on the surface thereof and using it as a photographic paper, a heat-sensitive recording paper, or a thermal transfer image-receiving paper. It is useful as a support.

[0018]

EXAMPLES The present invention will be described below with reference to examples. Example 1 Melt flow rate (MFR) 2.3 g / 10 min, melting point 155 [deg.] C. ethylene / propylene random copolymer "Mitsubishi Polypro EX-6" [trade name, manufactured by Mitsubishi Petrochemical Co., Ltd.]
50 parts by weight, melt flow rate 7.2 g / 10 minutes, melting point 145 ° C. ethylene / propylene copolymer “Mitsubishi Polypro FX-4 [trade name of Mitsubishi Yuka Co., Ltd.] 28 parts by weight, melt index 8 g / 10 minutes (280 ° C, load 2.16 kg) aromatic polycarbonate "Iupilon S-1000" [trade name of Mitsubishi Gas Chemical Co., Inc.] 2
2 parts by weight of styrene-grafted propylene resin "VMX DN-60" [trade name of Mitsubishi Petrochemical Co., Ltd.] having a melt index of 1.0 g / 10 minutes and a styrene graft amount of 15% by weight was added to 0 part by weight. And mix this mixture at 260 ° C.
After melt-kneading with a twin-screw kneader (made by Tokyo Seimitsu Co., Ltd.) set to
It was extruded in a strand form from a die, cooled and cut to obtain pellets. This pellet is melted / compressed / cooled by a press molding machine set at 260 ° C, 120 mm in length, 120 m in width.
A press sheet having a thickness of 1.5 mm and a thickness of 1.5 mm was obtained. This press sheet is 130 ° C with a small biaxial stretching machine (Iwamoto Seisakusho).
After heating, the film was sequentially stretched 5 times in the machine direction and 5 times in the transverse direction, and then annealed at 135 ° C. for 30 seconds to obtain a stretched film. Table 1 shows the thickness, porosity, opacity, occurrence of white spots, and stretching stability of the obtained film.

(Number of Occurrence of Whitening Spots) One sample having a length of 300 mm and a width of 300 mm is cut out from the central portion of the obtained film and set on a translucent table for drawing, and the presence or absence of whitening spots is observed. (Stability of Stretching) When 10 test pieces were carried out, no breakage of the film or detachment of the chuck occurred during the stretching, and the number of test pieces completed to the end is shown.

Examples 2 to 4 and Comparative Examples 1 to 5 Stretched films were prepared in the same manner as in Example 1 except that the resin composition and stretching temperature in Example 1 were changed to those shown in Table 1. To produce the wall thickness, porosity, opacity,
The occurrence of white spots and the stability of stretching were measured.

[0021]

[Table 1]

Example 5 Melt flow rate 2.3 g / 10 minutes, melting point 155 ° C.
Is an ethylene / propylene copolymer "Mitsubishi Polypro EX-
6 "[Mitsubishi Yuka Co., Ltd. (trade name)] 50 parts by weight, melt flow rate 7.2 g / 10 minutes, melting point 145 ° C ethylene-propylene copolymer" Mitsubishi Polypro FX-4 "
[Mitsubishi Yuka Co., Ltd. (trade name)] 29 parts by weight, melt index 8 g / 10 minutes (280 ° C., load 2.16 k)
g) Aromatic polycarbonate "Iupilon S-100"
0 "[Mitsubishi Gas Chemical Co., Ltd. (trade name)] 10 parts by weight,
Melt index 11g / 10min (190 ℃, 2.1
6 kg load) high density polyethylene "Mitsubishi Polyethylene PY"
-20A "[Mitsubishi Yuka Co., Ltd. (trade name)] 10% by weight
Was mixed with 1 part by weight of the styrene-grafted propylene resin "VMX DN-60" used in Example 1. This mixture was melt-kneaded in an extruder set at 260 ° C, extruded in a film form from a die, and cooled. I got a film. The film was heated by bringing it into contact with a heating roll at 135 ° C., and then stretched 4.5 times in the machine direction. Next, after cooling this film to a temperature of 60 ° C., it was heated in the oven with hot air of 155 ° C. using a tenter-type transverse stretching device, and then stretched 9 times in the transverse direction to obtain a hot air of 160 ° C. After the annealing treatment was performed, the ears were slit to obtain an opaque stretched resin film. The cross-sectional structure (2000 times) of this stretched film is shown in FIG. The stretching stability was good. The physical properties of the obtained stretched film were as follows. Thickness: 80 μm Porosity: 35% Opacity: 82% White spots: None

Example 6 Melt flow rate 0.8 g / 10 minutes, melting point 174 ° C.
70 parts by weight of propylene homopolymer having an average particle size of 1.5
A composition comprising 20 parts by weight of calcium bicarbonate of 10 μm and 10 parts by weight of high-density polyethylene having a melt index of 11 g / 10 min was melt-kneaded by an extruder set at 260 ° C., and then formed into a film by a die set at 250 ° C. Extrusion,
It cooled to the temperature of about 60 degreeC with the cooling roll. After heating this film by contacting it with a heating roll at 145 ° C.,
It was stretched 5 times in the machine direction. On both sides of this longitudinally stretched film,
Melt flow rate 2.3g / 10min, melting point 155 ℃
74 parts by weight of ethylene / propylene random copolymer of
A composition of 25 parts by weight of aromatic polycarbonate having a melt index of 8 g / 10 min and 1 part by weight of styrene-grafted propylene used in Example 1 was melt-kneaded in an extruder set at 260 ° C., and then a die set at 260 ° C. was used. It was extruded into a film and melt-pressed with a roll to obtain a laminate. Then, this laminate was cooled to a temperature of 60 ° C., heated with hot air in the oven using a tenter type transverse stretching device, and stretched 8.5 times in the transverse direction.
After annealing with hot air at 60 ° C., the ears were slit to obtain an opaque stretched resin film. This film was cut into 46-half sheets (length 788 mm, width 545 mm), and the offset ink "TS manufactured by Toyo Ink Mfg. Co., Ltd." TS
P-400 "(trade name)] and [Offset two-color printing machine" Diamond printing machine "(trade name) manufactured by Mitsubishi Heavy Industries, Ltd.) are used to print 2000 sheets in two colors and the ink edge pile on the blanket. When the number of prints (the number of printable sheets until a so-called sign of paper dust trouble occurs) is adversely affected by printing due to paper dust on the blanket or blanket, no sign of paper dust trouble is found at 2000 sheets. It was

Comparative Example 6 Melt flow rate 0.8 g / 10 minutes, melting point 174 ° C.
70 parts by weight of propylene homopolymer having an average particle size of 1.5
A composition comprising 20 parts by weight of calcium bicarbonate of 10 μm and 10 parts by weight of high-density polyethylene having a melt index of 11 g / 10 min was melt-kneaded by an extruder set at 260 ° C., and then formed into a film by a die set at 250 ° C. Extrusion,
It cooled to the temperature of about 60 degreeC with the cooling roll. After heating this film by contacting it with a heating roll at 145 ° C.,
It was stretched 5 times in the machine direction. On both sides of this longitudinally stretched film,
Melt flow rate 2.3g / 10min, melting point 155 ℃
60 parts by weight of the ethylene / propylene random copolymer and 40 parts by weight of calcium bicarbonate having an average particle size of 1.5 μm are melt-kneaded in an extruder set at 260 ° C.,
A film was extruded from a die set at 260 ° C. and melt-pressed with a roll to obtain a laminate. Then, after cooling this laminate to a temperature of 60 ° C., it was heated with hot air of 155 ° C. in the oven using a tenter type transverse stretching device, and then stretched 8.5 times in the transverse direction to 160 ° C. After annealing with hot air, the ears were slit to obtain an opaque resin stretched film. This film was used in Example 6.
When the number of printable sheets was evaluated by the same method as
It was a sheet.

[0025]

EFFECT OF THE INVENTION The stretched opaque resin film of the present invention is excellent in hiding power without causing white spots and paper dust trouble.

[Brief description of drawings]

1 shows a cross-sectional structure of an opaque resin stretched film having micropores obtained in Example 5 of the present invention.

[Explanation of symbols]

 1 Propylene resin matrix 2 Polycarbonate 3 Voids

Claims (2)

[Claims] 1. A thermoplastic resin containing 50 to 94% by weight of a propylene-based resin, 49 to 5% by weight of an aromatic polycarbonate resin and 0.1 to 7% by weight of a styrene-grafted propylene-based resin as a base material. Number 1] An opaque resin stretched film having pores having a porosity of 20 to 70% calculated in step 5 and an opacity of 75% or more. 2. An ethylene / propylene random copolymer having an MFR of 0.3 to 5 g / 10 min, an ethylene content of 0.5 to 8% by weight, and an MFR of 3 to 50 g / min.
10 minutes, ethylene content of 0.5-8 wt% ethylene
A propylene random copolymer, wherein the ethylene
2 g / 10 from MFR of propylene random copolymer
Based on a thermoplastic resin containing 5 to 50% by weight of an ethylene / propylene random copolymer having an MFR larger than the above, 49 to 5% by weight of an aromatic polycarbonate resin and 0.1 to 7% by weight of a styrene-grafted propylene-based resin. The stretched resin film has a porosity of 20 to 70% and an opacity of 7%.
An opaque resin stretched film which is 5% or more.