JP2516788B2 - Photosensitive material strip core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a negative or positive film for movies, a negative or positive microfilm, a long roll 35 mm film (J 135), a phototypesetting film, and a computer. A resin composition suitable for use as a core (roll core) for a photographic light-sensitive material strip (roll film or roll paper) such as a film, a computer typesetting paper, and a photographic paper, and a photosensitive material formed by molding the resin composition. The present invention relates to a material band core.

[Conventional technology]

Negative or positive films for movies are sold and used by being wound around a core for a band.
The photosensitive material strip-shaped cores are, for example, those shown in FIGS. 1 and 2.

In the core for a strip of photosensitive material shown in these figures, an outer cylinder 1 and an inner cylinder 2 having substantially the same width are arranged with their axes aligned, and the center of each of the cylinders 1 and 2 is aligned with this axis. They were connected by a single circular plate 3 arranged in a right angle direction. Then, on both surfaces of this annular plate, eight substantially circular ribs 4 formed by both cylinders and the annular plate are provided on each side, and both cylinders 1 and 2 are arranged symmetrically and in a radial direction from the axis. They were arranged concatenated.

A resin injection portion g corresponding to a resin injection port for injecting a thermoplastic resin when the core is formed by injection molding is formed substantially in the center of the end surface of one rib 4 of the ribs 4.

Further, a groove 6 for locking a claw piece or the like of a shaft of a camera or a projector is provided in the cylinder length direction of the inner cylinder 2, and a slit for inserting an end portion of a film in the cylinder length direction of the outer cylinder 1. A groove 7 is provided.

In order to improve the compressive strength, the applicant of the present invention has provided a resin injection part G with an outer cylinder 1 and an inner cylinder 2 as shown in FIGS. 3 and 4.
It is also proposed that at least one surface of the substantially fan-shaped annular plate surrounded by the two ribs 4 be provided at approximately the center (Shokaisho 61-
128256 publication).

Further, as shown in FIG. 5 and FIG. 6, a core for a band-shaped body has been proposed, which can improve the compressive strength even when the rib 8 is notched to form the notch 8 and the weight is reduced.
61-86367).

Furthermore, in order to improve the mold release property with the cavity,
As shown in FIGS. 7 and 8, a core for a band-shaped body was proposed in which convex portions 9 ... 9 were formed in a portion in contact with the mold core.

In addition, examples of the core for the band-shaped body include a flange integrally formed (Japanese Utility Model Laid-Open No. Sho 49-18536, etc.), and one of the flanges can be attached and detached so that a long film can be stored in a wound state. There was also a thing (Japanese Utility Model Publication No. 59-24025).

Conventionally, impact-sensitive polystyrene resin obtained by blending or polymerizing polyethylene rubber with synthetic rubber (mainly using butadiene rubber) has been used for the core for the photosensitive material strip as described above.

[Problems to be solved by the invention]

However, the above-mentioned conventional resins have low drop strength and surface strength, are easily dissolved by a solvent, their shapes are destroyed, and synthetic rubber is expensive, which is not only adversely affecting photographic properties, but also makes them milky white. There was a problem of low transparency. Further, there is a problem that the weld line is strongly generated, and the compressive strength and the drop strength are reduced.

The present invention solves the above problems, resin composition with good dimensional accuracy, solvent resistance, good chemical resistance, high strength, good photographic properties, less fog, inexpensive and good injection moldability An object of the present invention is to provide a core for a photosensitive material strip formed by molding a product.

[Means for solving problems]

In order to achieve the above object, the present invention provides a specific polypropylene resin and a linear low density polyethylene (hereinafter referred to as L-LDRE).
(Indicated by the symbol) is a core for a photosensitive material strip formed from a resin composition containing a resin, a lubricant and an antioxidant.

That is, the core for a strip of photosensitive material of the present invention has a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.5 to 8, melt index of 10 to 60 g / 10 minutes, and bending elastic modulus of 8000 kg / c.
m ² or more, Izod impact strength 2.0kg · cm / cm ² or more, the Rockwell hardness is more than the polypropylene resin 70R 70-3
0% by weight, melt index 3 to 50 g / 10 minutes, density 0.910 to 0.935 g / cm ³ , Olsen rigidity 1500 kg / cm ² or more, Shore hardness 40D or more L-LDPE resin 30 to 70% by weight And 0.01 to 2.0 weight of lubricant and 0.01 to 1.0 weight of antioxidant.
And a resin composition containing 1% by weight of the resin composition.

Melt index of polypropylene resin used in the present invention (JIS K-7210 = L condition of ASTM D-1238, test temperature 2
Measured at 30 ° C and a test load of 2.16 kgf (hereafter referred to as MI) is 10
~ 60g / 10 minutes, preferably 20-50g / 10 minutes, particularly preferably
It is 30-40g /. When the MI is less than 10 g / 10 minutes, the resin fluidity is poor, so weld lines are strongly generated, drop strength and compressive strength are lowered, and sink marks are also large, resulting in poor appearance and use as cores for photographic light-sensitive materials. In this case, pressure fogging occurs at the rib portion. Furthermore, the injection moldability is poor and the molding cycle becomes long. Even if the resin temperature is raised, short shots are likely to occur, sink marks are large, cooling time is long, and it cannot be put to practical use. On the other hand, when the MI exceeds 60 g / 10 minutes, the physical strength is lowered, the surface hardness is reduced, and the rigidity is too small to be put into practical use. Furthermore, burrs and stringiness are likely to occur.

The flexural modulus (JIS K-7112) is 8000 kg / cm ² or more, preferably 9000 kg / cm ² or more, and particularly preferably 10,000 kg / cm ²
That is all. If it is less than 8000 kg / cm ^2, it is not flexible and cannot be put into practical use when mixed with L-LDPE resin for improving the Izod impact strength.

Izod impact strength (JIS K-7110, 23 ° C) is 2.0 kg
· Cm / cm ² or more, preferably 3.0kg · cm / cm ² or more, particularly preferably 4.0kg · cm / cm ² or more. If it is less than 2.0 kg · cm ² / cm, it will be blended to improve Izod impact strength.
Since the amount of LDPE resin must be increased, as a result, the rigidity is reduced and deformation due to external force is likely to occur, making it difficult to secure the light shielding property. In addition, the number of remaining gates and stringing is increased, and the fluidity of the resin is lowered, so that the generation of weld lines is increased and it cannot be put to practical use.

In order to improve wear resistance and prevent scratches, the Rockwell hardness (JIS K-7202) is 70R or higher, preferably 80R or higher, particularly preferably 90R or higher. If it is less than 70R, the groove for locking the core with the claw of the processor, the projector or the winder, the slit for inserting the end of the strip, the resin powder due to wear on the flange for holding the strip, etc. If the resin powder adheres to the belt-shaped body due to scratches or the like, a failure will occur. In addition, scratches and abrasion are likely to occur during the transportation process and processing and packaging. In particular, in the case of photographic light-sensitive material roll-shaped films such as movie films and microfilms, computer typesetting papers, etc., if the resin powder adheres, the commercial value will be lost and it will cause a serious failure and cannot be put to practical use.

As long as it is a polypropylene resin having the above characteristics, even homopolypropylene resin is a copolymer resin of propylene and α-olefin having 2 to 8 carbon atoms, such as propylene / ethylene random copolymer resin or propylene / ethylene. It may be a block copolymer resin or the like. From the viewpoint of preventing whitening, propylene is preferably 99.5 to 90% by weight.
And ethylene are 10 to 0.5% by weight of a propylene / ethylene random copolymer resin, particularly preferably propylene is 99 to
It is a propylene / ethylene random copolymer resin containing 93% by weight and 7 to 1% by weight of ethylene.

Regardless of which type of polypropylene resin is used, the molecular weight distribution (Mw weight average molecular weight / n number average molecular weight) measured by GPC (Gel Permeation Chromatograph) improves dimensional accuracy, prevents sink marks, increases rigidity, secures strength and injection molding. From the viewpoint of balance such as appropriateness, it is 1.5 to 8, preferably 2 to 6, and particularly preferably 2.5 to 5. When the molecular weight distribution is less than 1.5, the properties are excellent, but the resin polymerizability is poor and the cost is high, and the suitability for injection molding is poor, making practical application difficult.

It is preferable that the polypropylene resin contains various inorganic and / or organic nucleating agents in terms of rigidity, abrasion resistance, suitability for injection molding (prevention of string pulling, prevention of gate residue, prevention of burrs, improvement of releasability, etc.). . It is particularly preferable to include an organic nucleating agent.

The method for polymerizing the polypropylene resin is not particularly limited, but the gas phase polymerization method is preferable because it is inexpensive and has a small molecular weight distribution (narrow molecular weight distribution, good dimensional accuracy, and small sink mark).
As a catalyst to be used, a polypropylene resin using a stereoregular catalyst is preferable from the viewpoint of ensuring the properties required for the present invention.

70 to 30% by weight of such polypropylene resin is contained. If it exceeds 70% by weight, sink marks are generated, the physical strength is lowered, and the molding shrinkage rate is increased. If it is less than 30% by weight, the rigidity, wear resistance and injection moldability are deteriorated.

In order to significantly improve the Izod impact strength by blending with the above-mentioned polypropylene resin, and greatly improve the dimensional accuracy and sink mark, the L-LDPE resin essential to the present invention is MI (JI
(Test temperature of SK-6760 measured at 190 ℃, test load 2.16kgf)
Is 3 to 50 g / 10 minutes, preferably 5 to 30 g / 10 minutes, particularly preferably 7 to 20 g / 10 minutes. If the MI is less than 3 g / 10 minutes, the fluidity of the resin will be poor and weld lines or short shots will easily occur, making practical application difficult. Also, 50g / 10
If it exceeds, the drop strength is not improved so much, the rigidity is small, there are many occurrences of stringing and gate residue, the wear resistance is poor, and the ESCR (JIS K-6760) is poor and practical application is difficult.

Density (JIS K-6760) is 0.910 to 0.935 g / cm ³ , preferably 0.915 to 0.930 g / cm ³ , particularly preferably 0.917 to 0.928 g
a / cm ^3. If it is less than 0.910 g / cm ³ , the rigidity is insufficient and the suitability for polymerization is poor, so it is expensive, and the abrasion resistance is poor and it is difficult to put it into practical use. On the other hand, if it exceeds 0.935 g / cm ³ , the drop strength is poor and practical application is difficult.

The Olsen stiffness (JIS K-7106) is at least 1500 kg / cm ² , preferably at least 1800 kg / cm ² , particularly preferably at least 2100 kg / cm ² . If it is less than 1500 kg / cm ² , the compressive strength is insufficient and the winding length of the strip becomes long, and if the tightening pressure becomes large, the core is deformed and it cannot be put to practical use.

Shore hardness (JIS K-7215) is 40D or more, preferably 45
D or more, particularly preferably 50D or more. When it is less than 40D, the same result as when the Rockwell hardness of polypropylene resin is less than 70R is obtained and it cannot be put to practical use.

It can be said that the molecular weight distribution is exactly the same as that of the polypropylene resin.

L-LDPE resin is called a third polyethylene resin,
It is a low-cost, high-strength resin that meets the demands of the era of energy and resource savings combining the advantages of both medium, low density and high density polyethylene resins. This resin is presently mostly low-pressure process with ethylene and 3 to 13 carbon atoms, preferably 4
It is a copolymer of 8 to 8 α-olefins, and is a low-to-medium density polyethylene resin having a linear straight chain with short branch having an ethylene content of 85 to 99.5 mol%.
The recently developed high-pressure improved L-LDPE resin is also effective.

As the α-olefin, butene-1, octene-1,
Hexene-1, 4-methylpentene-1, heptene-
1, etc. are used, the amount of which is of the order of 0.5 to 15 mol% of the polymer. Density is generally considered to be low and medium density polyethylene resin, but most commercial products have a density within the range of 0.87 to 0.95 g / cm ² .

Specific examples of L-LDPE resins are G resin (UCC), Dow Rex (Dow Chemical), Sclear (Dupont Canada), Marlex (Phillips), Neo-Zex and Ulto-Zex (Mitsui Sekiyu). Chemistry), Nisseki Linirex (Nippon Petrochemical), Stamilex (DSM), and so on.

Among these L-LDPE resins, particularly preferable in the present invention from the viewpoints of physical strength, injection moldability, etc. are ethylene content of 90 to 99.5 mol%, α-olefin content of 0.5 to 10 mol% and melt. Index (hereinafter referred to as MI) is 3 to 50g /
10 minutes (JIS K-6760), density 0.910 to 0.935 g / cm ² (JIS
K-6760), and an α-olefin having 6 to 8 carbon atoms in a liquid phase process or a gas phase process.

A particularly preferred representative example is the trade name of Ultox and α-olefin side of Mitsui Petrochemical Co., Ltd. in which ethylene is copolymerized with 4-methylpentene-1 having 6 carbon atoms as an α-olefin side chain. There are Stamilex manufactured by DSM Co., Ltd. and Dow Rex manufactured by Dow Chemical Co., which are copolymerized with octene-1 having 8 carbon atoms as a chain (these three companies are L-LDPE resins obtained by the liquid phase process).

The lubricant is used to improve injection moldability, mold releasability and fluidity. The content of this lubricant is 0.01% by weight or more, preferably 0.03 to 2.0% by weight, particularly preferably 0.05 to 0.5% by weight. If it is less than 0.01% by weight, the releasability of the core from the mold is poor, and static electricity is easily generated and the surface is easily scratched, which makes practical application difficult. However, if the amount is too large, the amount of injection will fluctuate due to slipping with the screw and the plasticizing ability will be insufficient, so that it cannot be put to practical use. Further, when the amount of bleed-out is increased and the bleed-out amount adheres to a photosensitive material, problems such as development inhibition are caused.

Representative lubricants and their manufacturers are described below, but the invention is not limited thereto.

(1) Silicone-based lubricant; various grades of dimethylpolysiloxane and this compound (Shin-Etsu Silicone, Toray Silicone), etc. (2) Oleic acid amide-based lubricant; Armoslip CP (Lion / Akzo), Neutron (Nippon Seika), Neutron E-18 (Nippon Seika), Amide O (Nitto Kagaku),
Alfro-E-10 (Nippon Yushi), Diamond Mid O-200
(Nippon Kasei), Diamid G-200 (Nippon Kasei), etc. (3) Erucamide amide lubricant; Alfuro-P-10 (Nippon Yushi), Neutron S (Nippon Seika), etc. (4) Stearamide amide Lubricant; Alfro-S-10
(Nippon Yushi), Neutron 2 (Nippon Seika), Diamid 200 (Nippon Kasei), etc. (5) Bis fatty acid amide lubricant; Bisamide (Nippon Kasei), Diamid 200 bis (Nippon Kasei), Armowax EBS ( (Lion Akzo) etc. (6) Alkylamine lubricants; Electrostripers
There is TS-2 (Kao soap) etc.

The amount of these lubricants that do not adversely affect the packaging of photographic light-sensitive materials is 0.01 to 2.0% by weight, and they may be used alone or in combination of two kinds. The fatty acid amide-based lubricant preferred in the present invention has 8 to 50 carbon atoms,
Particularly preferred is 15 to 35.

The oxygen inhibitor is for preventing the resin from burning and coloring. The content of this antioxidant is 0.01% by weight or more, preferably 0.03-1.0% by weight, particularly preferably 0.05 to 0.5% by weight. If it is less than 0.01% by weight, resin burning occurs and continuous injection molding cannot be performed for a long time, which makes practical application difficult. However, if the amount is too large, in the case of a core for a belt-shaped photographic light-sensitive material, quality defects such as fogging and sensitivity fluctuation will occur. Therefore, it is preferably 1.0% by weight or less.

Representative antioxidants include those shown below.
The present invention is not limited to these.

Phenolic n-octadecyl-3 (3 ', 5'-di-tert-butyl 4'hydroxyphenyl) propinate, 2,6-di-tert-
Butyl 4-methylphenol, 2,6-di-t-butyl-p
-Cresol, 2,2'-methylenebis (4-methyl-6)
-T-butylphenol), 4,4'-thiobis (3-methyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), stearyl-β (3,5- Di-4-butyl 4-hydroxyphenyl) propionate, 1,1,3-tris ((2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4, 6-Tris (3,5-di-t
-Butyl-4-hydroxybenzyl) benzene, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propinate, tetrakis [methylene-3
(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane etc. Sulfur-based dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, lauryl Stearyl thiodipropionate, distearyl-3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, etc.Phosphorus-based trinonylphenyl phosphite, triphenyl phosphite, etc., especially 2,6-di-t Butyl-p-cresol (BHT) and low volatility high molecular weight phenolic antioxidant (trade name Ireg
anox 1010, Iriganox 330, Topano ICA, etc.), dilauryl thiodipropionate, distearyl thiodipropionate, dialkis phosphate, etc., and it is effective to use one or more, especially two or more thereof in combination.

Preferable are phenolic antioxidants, and commercially available products include Irganox of Ciba-Geigy and Sumilizer BHT, Sumilizer BP-76, Sumilizer of Sumitomo Chemical Co., Ltd.
WX-R, Sumilizer BP-101 and the like.

Further, when used in combination with carbon black or the like, the antioxidant effect is synergistically exerted.

The resin composition containing four kinds of the polypropylene resin, the L-LDPE resin, the lubricant and the antioxidant, which are essential to the present invention, further contains a nucleating agent to improve rigidity, injection moldability, and molding failure (yarn). It is preferable from the viewpoints of reduction in pulling, gate residue, burrs, etc., improvement of transparency, improvement of body abrasion resistance, and improvement of heat resistance.

Additives other than those described above can be added in necessary amounts in the resin composition used for molding the core for a light-sensitive material strip of the present invention, if necessary.

Typical examples of the additives are described below, but the present invention is not limited thereto and can be selected from all known ones.

In addition, other chlorine absorbers, light-shielding substances, white pigments, coloring dyes, etc. can also be added.

The use of the core for a strip of photosensitive material of the present invention is suitable, for example, for the core of a strip of various photosensitive material.

Further, various molding methods such as injection molding are used as the molding method of the resin composition for the purpose of manufacturing the core for the photosensitive material strip of the present invention, and this injection molding also includes in-mold vacuum injection molding.

[Action]

The resin composition for molding the core for the photosensitive material strip of the present invention is lightweight and excellent in injection moldability, appearance, drop strength, solvent resistance, transparency, processability, abrasion resistance, etc. There are few molding failures such as pulling, weld lines, twisting, and deformation, and it has excellent dimensional accuracy and flexibility.

〔Example〕

Inventive product I Inventive product I has MI of 38 g / 10 minutes and flexural modulus of 11000 kg / cm.
² 、 Izod impact strength 4.3kg ・ cm / cm ² , Rockwell hardness 90R propylene amount 96.5% by weight, ethylene amount
50% by weight of polypropylene resin, which is a propylene / ethylene random copolymer resin of a gas phase polymerization method consisting of 3.5% by weight, MI is 18 g / 10 minutes, density is 0.910 g / cm ³ , Olsen rigidity is 2200 kg / cm ² , Solution polymerization method L-LF which is a copolymer resin of ethylene and 4-methylpentene-1 having a Shore hardness of 50D.
PR resin 49.7% by weight and BHT 0.2% by weight as antioxidant
And 0.1% by weight of oleic acid amide as a lubricant.

The front view is shown in FIG. 5 and the rib shape is the core shown in FIG. 6, which is for winding 2000 feet of 35 mm wide motion picture film having an outer diameter of 3 inches. The dimensions are the thickness of the outer cylinder 1. 2.1m
m, the inner cylinder 20 has a wall thickness of 20.5 mm, the annular plate 3 has a wall thickness of 2.2 mm, the rib 4 has a wall thickness of 2.0 mm, the outer cylinder 1 has an outer diameter of 76.2 mmφ, and the inner cylinder 2 has an inner diameter of 25.9 mmφ. , And the cylinder length of both cylinders is 34.5 mm. The size of the rib 4 is 15 mm in length and 21 mm in width.
The notch 8 is formed from the both corners of the outer edge of the rib 4 into the cylinders 1, 2
It obliquely descends at an angle of 30 degrees with the cylinder length direction, travels 10 mm parallel to the edge on the side of the annular plate 3, and is an inverted trapezoid as a whole.

The injection molding method used in the present invention is a generally used injection molding method using a cold runner, and the injection molding machine is a mold with a mold clamping pressure of 100 tons.

Invention Product II The resin composition is the same as Invention Product I. The front view is shown in Fig. 3 and the shape of the rib is shown in Fig. 4. The rib is 10 mm in length × 21 in width.
It is the same as the product I of the present invention except that it has a rectangular shape of mm.

Invention Product III The resin composition is the same as Invention Product I. The front view is shown in Fig. 1, the rib shape is shown in Fig. 2, and the rib size is 15 mm in length.
It is the same as the product I of the present invention except that it is a rectangle having a width of 21 mm.

Invention product IV Polypropylene resin same as invention product I 54.4% by weight
And MI is 10g / 10min, density is 0.925g / cm ³ , Olsen rigidity is
L-LD by solution polymerization method, which is a copolymer resin of ethylene and 4-methylpentene-1 with 2500 kg / cm ² and Shore hardness of 52D.
45 wt% PE resin and 0.2 wt% BHT as an antioxidant,
1,3,2,4-di (methylbenzylidene) as an organic nucleating agent
It consists of 0.2% by weight of sorbizol.

The front view is as shown in Fig. 7 and the rib shape is as shown in Fig. 8, and the height of the inner surface of the outer cylinder 1 that contacts the mold core is 0.1 m.
This is the same as the product I of the present invention except that a convex portion 9 having a width of 0.5 mm and a resin injection portion is provided at the tip of the rib.

Invention product V The same polypropylene resin as invention product I, 55.0% by weight,
MI is 12 g / 10 min, density of 0.920 g / cm ^3, Olsen stiffness of 2500
44.5% by weight of L-LDPE resin of vapor phase polymerization method which is a copolymer resin of ethylene and butene-1 with kg / cm ² and Shore hardness of 50D, 0.3% by weight of BHT as an antioxidant, and phosphorus-based It consists of 0.1% by weight of antioxidant and 0.1% by weight of oleic acid amide as a lubricant.

 The shape is the same as the product IV of the present invention.

Comparative product I This product is made of the same polypropylene resin as the product of the invention III, and has the same shape as the product of the invention III.

Comparative product II It is composed only of the same L-LDPE resin as the product of the invention III, and has the same shape as the product of the invention III.

Conventional product I Made of impact resistant polystyrene resin (manufactured by Asahi Kasei Corp., trade name Styron), and has the same shape as the product III of the present invention.

Table 1 shows the comparison test results of the products I to V of the present invention, the comparative products I and II, and the conventional product.

The evaluation is based on the following: ◎: Excellent ○: Excellent ●: Practical limit ▲: Problematic, need improvement ×: Not practical * A: Cost reduction (resin cost) The conventional resin price is 100 Cost ratio when performing * B: Necessity of gate residual processing When using the core for strips immediately after injection molding without processing the residual part of the gate part, if there is a hindrance to packaging work or development processing work "Yes" and "No" when there is no problem.

* C: Injection moldability Sensory evaluation based on the releasability of the molded product during injection molding and the degree of occurrence of molding failure * D: Sink mark Visual inspection of the injection molded product to determine whether it is practical * E: Weld line Degree of occurrence Same as above * F: Transparency Same as above * G: Impact strength (falling strength) When 2,000 feet of 35 mm wide film positive film for film is wrapped around the sample and dropped from the height of 30 cm to the floor Practicality is judged by the degree of sample destruction * H: Solvent resistance Immersion of sample in alcohol solution or triol solution for comparison of resistance * I: Abrasion resistance Depends on the degree of abrasion after long-term use in a processor Evaluation [Effect of the invention] The resin composition for core molding of the photosensitive material strip according to the present invention,
When formed by injection molding, etc., the density of the resin is small, the drop strength is great even if it is made lightweight, it has excellent wear resistance, transparency and solvent resistance, and molding of gate residue, sink marks, weld lines, short shots, etc. Since it uses a general-purpose resin that does not break down and is inexpensive, and it does not require gate remaining processing, it is low in cost, excellent in processability, appearance, and physical strength, and the injection molding cycle time can be shortened.

[Brief description of drawings]

FIG. 1 is a front view of a core for a band formed by using a resin composition of the present invention product, a comparative product, and a conventional product, FIG. 2 is a partial sectional view of the same as above, and FIG. 3 is a core for another band. A front view, FIG. 4 is a partial sectional view of the same as above, and FIG. 5 is a front view of another core for a band-shaped body.
6 is a partial sectional view of the same as above, FIG. 7 is a front view of another core for a band-shaped body, and FIG. 8 is a partial sectional view of the same. 1: Outer cylinder, 2: Inner cylinder, G: Resin injection part

Claims (1)

(57) [Claims] 1. A molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.5 to 8, melt index of 10 to 60 g / 10 minutes,
Flexural modulus of 8000 kg / cm ² or more, Izod impact strength of 2.
0kg · cm / cm ² or more, and Rockwell hardness is more than the polypropylene resin 70R 70 to 30 wt%, a melt index of 3 to 50 g / 10 min, density of 0.910 to 0.935 g / cm ^3, Olsen rigidity 1500 kg / 30 to 70% by weight of linear low-density polyethylene resin with cm ² or more and Shore hardness of 40 D or more, and lubricant from 0.01 to
A core for a photosensitive material strip, which is obtained by molding a resin composition containing 2.0% by weight and 0.01 to 1.0% by weight of an antioxidant.