JP2607900B2 - Resin composition for producing injection molded articles for photographic photosensitive materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an injection molded article for a photographic photosensitive material, for example, a method in which a photosensitive band material such as a roll of photographic paper or a photographic film is exposed to sunlight or The present invention relates to a resin composition suitable for producing a light-shielding container or the like which can be loaded under room lighting.

[Conventional technology]

Various types of light-shielding containers for the photosensitive band are disclosed. For example, Japanese Utility Model Laid-Open No. 55-88980,
JP-A-13543, JP-A-61-49353, JP-A-61-6712
No. 8, JP-B-56-16608, JP-B-61-2998, JP-A-55-124140, JP-A-57-128333, JP-A-57-172344, JP-A-57-172344 60-156058, JP-A-60-211453, JP-A-61-203453, JP-A-61-219040, JP-A-61-255339, JP-A-61-255340 JP-A-62-172344, JP-B-59-36736, U.S. Pat.No. 4,148,395, U.S. Pat.No.4,179,028, U.S. Pat.
2,035.

Japanese Utility Model Laid-Open Publication No. 61-67128 discloses a photosensitive band container as shown in FIG. That is, it has a quadrangular tubular body member 1 and an end cap 2, and the tubular body member 1 is open at both ends and has one slot 3 adjacent to one corner. Extends in all axial directions of the tubular member 1 and is a narrow outlet through which the photosensitive band 4 passes. The slot 3 has a structure for keeping the photosensitive band 4 in the container in a light-shielding state. Then, end caps 2 are attached to close the openings of the tubular body member 1 respectively.

Japanese Patent Application Laid-Open No. 55-88980, Japanese Utility Model Application Laid-Open No. 55-113543, Japanese Utility Model Application Laid-Open No. 61-49353, and Japanese Patent Application Laid-Open No. , JP 5
JP-A-7-128333, JP-A-60-211453, JP-B-59
No. 36736.

FIG. 2 shows an example of another end cap. The end cap 2 is formed in a double structure of an outer flange 7 and an inner flange 8, and a reinforcing rib 9 is formed in the inner flange 8.

Further, another example of an end cap is disclosed in
FIG. 3 and FIG. 4 disclosed in Japanese Patent Publication No. 40-240.

Heretofore, polyolefin resins such as polypropylene resins and polyethylene resins, polystyrene resins, ABS resins, and the like have been used for the above end caps. In particular, impact-resistant polystyrene resins have often been used to ensure appearance, dimensional accuracy, and physical strength.

[Problems to be solved by the invention]

The above-mentioned conventionally used impact-resistant polystyrene resin and ABS resin are very expensive and could not provide a light-shielding container at low cost.

In addition, polypropylene resin has low drop strength (particularly low temperature at low temperature) and a large molding shrinkage during molding, so that the occurrence of sink marks is large, the appearance is deteriorated, and the dimensional accuracy is poor.

In particular, the end cap having a flange portion as shown in FIG. 2 requires a sufficient height to assure light-shielding property when assembling with the tubular body portion 1, and therefore, warpage is likely to occur. .

Using the end cap 2 having the flange portions 7 and 8 having such inward warpage, the photosensitive strip 4 is housed in the tubular body portion 1 in a dark room, and the end caps are placed at both ends of the tubular body portion 1. When fitting the two into a photosensitive strip material container, dimensional accuracy and an obstacle in assembling work occur. Therefore, the work efficiency is poor, it is difficult to secure light-shielding properties, and there is a problem that intermediate products with incomplete assembly frequently occur.

Therefore, the inward warpage of the flange portion is corrected by changing the molding conditions at the time of forming the end cap, but it has not been possible to obtain a sufficient effect, and there has been a problem that the molding cycle becomes longer and the cost is increased. .

In the case of polyethylene resin, rigidity is insufficient, and since it is a crystallized resin like polypropylene resin, there is a problem that molding shrinkage is large, dimensional accuracy is poor, and sink marks and warpage are generated.

The present invention solves the above problems, has a large physical strength, a small molding shrinkage, a sink mark, a small occurrence of warpage, excellent abrasion resistance, a molding failure such as a short shot of a resin injection port trace. An object of the present invention is to provide a resin composition for producing a small and inexpensive injection molded product for a photographic light-sensitive material.

[Means for solving the problem]

For the present invention to achieve the above object, a melt index of 10 to 60 g / 10 min, a flexural modulus of 8000 kg / cm ² or more, Izod impact strength 2.0kg · cm / cm ² or more, a Rockwell hardness of more than 70R, 70 to 30% by weight of a polypropylene resin having a molecular weight distribution of 1.5 to 8 and a melt index of 3 to 50 g /
10 minutes, density 0.910 ~ 0.935g / cm ³ , Olsen rigidity 1500k
g / cm ² or more, Shore hardness 40D or more, molecular weight distribution 1.5 ~
8 to 30 to 70% by weight of the linear low density polyethylene resin;
A resin for producing an injection-molded article for photographic photosensitive materials, comprising 0.01 to 2% by weight of a lubricant, 0.01 to 1.0% by weight of an antioxidant, and 0.01 to 30% by weight of a light-shielding substance. It is composed of a composition.

Melt index of the polypropylene resin used in the present invention (hereinafter referred to as MI, temperature of 230 by the measurement method of JIS K-7210)
The value measured at 2.16kg f at ° C. ) Is 10 to 60 g / 10 min, preferably 20 to 50 g / 10 min, particularly preferably 30 to 40 g / 10 min. If it is less than 10 g / 10 minutes, resin flowability is poor, weld line generation is strong, drop strength and compressive strength are reduced, sink marks are large, appearance is poor, and when used for injection molded products for photographic photosensitive materials, Light fogging occurs due to the warpage of the cap. In addition, the injection moldability is poor and the molding cycle becomes longer. Further, even if the resin temperature is increased, short shots are liable to occur, the sink mark is large, and the cooling time is prolonged, so that practical use is not possible. On the other hand, if it exceeds 60 g / 10 minutes, the physical strength is reduced, the surface hardness is reduced, and the rigidity is too small to be practical. Further, burrs and stringing 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 , a resin mixed with L-LDPE resin which is more flexible and blended to improve Izod impact strength has insufficient compressive strength and cannot be put to practical use.

Izod impact strength (JIS K-7110, 23 ° C) is 2.0kg · c
m / 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 / cm ² , the amount of L-LDPE resin for improving the Izod impact strength must be increased, the gate residue and stringing increase, and the rigidity is reduced. It becomes difficult to secure the property. Further, since the resin fluidity is reduced, the occurrence of weld lines is increased, and the resin cannot be put to practical use.

The Rockwell hardness (JIS K-7202) is set to 70R or more, preferably 80R or more, and most preferably 90R or more to improve abrasion resistance and prevent scratching. If it is less than 70R, scratches and wear debris are likely to occur during injection molding and during transportation of the molded product. A particular problem is that abrasion debris, abrasions, etc. are generated during use in a developing machine or the like, and a failure occurs in which resin powder adheres to the photosensitive belt-like belt. In particular, in the case of color photographic paper, microfilm, COM film, computer-printed typesetting film, computer-printed typesetting photographic paper, etc., if resin powder adheres, the commercial value will be lost and serious failure will occur, making it impractical.

As long as the polypropylene resin has properties as described above, even a homopolypropylene resin is a copolymer resin of propylene and an α-olefin having 2 to 8 carbon atoms, such as a propylene / ethylene random copolymer resin or propylene / ethylene. It may be a block copolymer resin or the like. Propylene preferably 99.5-90% by weight in terms of prevention of whitening
And ethylene 10 to 0.5% by weight of a propylene / ethylene random copolymer resin, particularly preferably 99 to 93% of propylene.
It is a propylene / ethylene random copolymer resin containing 7 to 1% by weight of ethylene and 7 to 1% by weight.

Regardless of the type of polypropylene resin used, the molecular weight distribution measured by GPC (Gel Permeation chromatograph) (w weight average molecular weight / n number average molecular weight)
Is preferably 1. in terms of balance of dimensional accuracy improvement, sink mark prevention, rigidity increase, strength securing and injection molding suitability.
5-8, particularly preferably 2-6, most preferably 2.5-5
It is. When the molecular weight distribution is less than 1.5, the properties are excellent, but the resin polymerizability is poor, so that not only the cost is high but also the suitability for injection molding is poor.

It is preferable that the polypropylene resin contains various inorganic and / or organic nucleating agents because rigidity, abrasion resistance, suitability for injection molding and the like are improved. It is particularly preferable to include an organic nucleating agent.

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

Such a polypropylene resin is contained in an amount of 30 to 70% by weight.

The L-LDPE resin which is essential to the present invention is blended with MI to greatly improve the Izod impact strength by blending with the above-mentioned polypropylene resin, and to greatly improve dimensional accuracy and sink mark.
(Measured at a temperature of 190 ° C. and a load of 2.16 kgf by the measuring method of JIS K-6760) is 3 to 50 g / 10 min, preferably 5 to 30 g / 10 min.
Min, particularly preferably 7 to 20 g / 10 min. If the MI is less than 3 g / 10 minutes, the flowability of the resin is poor and weld lines or short shots are likely to occur, making it difficult to put into practical use.
Also, if it exceeds 50 g / 10 minutes, the drop strength cannot be improved much, the rigidity is small, and stringing and gate residue often occur,
Poor wear resistance and poor ESCR (JIS K-6760), making it difficult to put into practical use.

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, the polymerization suitability is poor, the cost is high, and the abrasion resistance is inferior. If it exceeds 0.935 g / cm ³ , the drop strength is inferior and it cannot be put to practical use.

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 if the winding length of the band is long and the weight is large, the core holding portion is deformed and cannot be put to practical use.

The Shore hardness (JIS K 7215) is 40D or more,
It is preferably at least 45D, most preferably at least 50D. 40
Below D, Rockwell hardness of polypropylene resin is 70R
The same result as in the case of less than the above cannot be put to practical use.

Regarding the molecular weight distribution, the same can be said for 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. Most of this resin has a low pressure method containing ethylene and carbon atoms of 3 to 13, preferably 4 to 8 carbon atoms.
It is a low- and medium-density polyethylene resin having a structure obtained by copolymerizing two α-olefins and having a linear straight chain with a 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. The density is generally low or medium-density polyethylene resin, but many commercial products have a density in the range of 0.87 to 0.95 g / cm ³ .

If specific examples of L-LDPE resin are given by trade names, G resin (UCC), Dourex (Dow Chemical), Screa (DuPont Canada), Marlex (Philips), Neozex and Ultrazex (Mitsui Oil) Chemical), Nisseki Linirex (Nippon Petrochemical), Stamirex (DSM), and the like.

Among these L-LDPE resins, particularly preferred from the viewpoint of physical strength and the like are those having an ethylene content of 90 to 99.5 mol%, α-
Olefin content is 0.5 to 10 mol%, melt index (hereinafter referred to as MI) is 3 to 50 g / 10 min (JIS K 6760), density is 0.910 to 0.935 g / cm ³ (JIS K 6760), and α- It is obtained by a liquid phase method or a gas phase method process in which the olefin has 6 to 8 carbon atoms.

A particularly preferred representative example is given by trade name: Ultzex and α-olefin side of Mitsui Petrochemical Co., Ltd. obtained by copolymerizing ethylene with 4-methylpentene-1 having 6 carbon atoms as an α-olefin side chain. There are DSM's Stamirex and Dow Chemical's Dourex in which octene-1 having 8 carbon atoms is copolymerized as a chain (these are L-LDPE resins obtained by a co-liquid phase process of the above three products). ).

The lubricant is used for improving injection moldability, releasability, fluidity, and the like. The content of this lubricant is 0.01% by weight or more,
Preferably 0.32 to 2.0% by weight, particularly preferably 0.05 to 0.5%
% By weight. If the amount is less than 0.01% by weight, the releasability of the core from the mold is poor, static electricity is easily generated, and the surface is easily scratched, which makes practical use difficult. However, if the amount is too large, the injection amount fluctuates due to slippage with the screw or the plasticizing ability is insufficient, so that it cannot be put to practical use. In addition, the bleed-out amount increases, and if it adheres to a photosensitive material or the like, a development obstacle occurs. Therefore, 2.0
It is preferable that the content be not more than% by weight.

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

(1) Silicone lubricant; various grades of dimethylpolysiloxane and this compound (Shin-Etsu Silicone, Toray Silicone), etc. (2) Oleic amide lubricant; Armoslip CP
(Lion Akzo), Neutron (Nippon Seika), Neutron E-18 (Nippon Seika), Amide O (Nitto Kagaku), Alflow E-10 (Nippon Oil & Fats), Diamond Mid O
-200 (Nippon Kasei), Diamid G-200 (Nippon Kasei)
(3) Erucamide amide lubricant; Alflow P-10 (Nippon Oil & Fats), Neutron S (Nippon Seika), etc. (4) Stearamide amide lubricant; Alflow S-10
(Nippon Oil & Fats), Neutron 2 (Nippon Seika), Diamid 200 bis (Nippon Kasei), etc. (5) Bis fatty acid amide-based lubricants: Bisamide (Nippon Kasei), Dimid 200 bis (Nippon Kasei), Armowax EBS ( (Lion Akzo), etc. (6) Alkylamine-based lubricants: Electrostripper TS-2 (Kao Soap) and the like.

The amount of these lubricants which do not adversely affect these when used in injection molded articles for photographic light-sensitive materials is 0.01 to 2.0% by weight, and may be used alone or in combination of two or more. The preferred fatty acid amide lubricant of the present invention has 8 to 50 carbon atoms.
And particularly preferably 15 to 35.

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

Representative antioxidants include the following, but the invention is not limited thereto.

Phenolic n-octadecyl-3 (3 ', 5'-di-t-butyl4'hydroxyphenyl) propinate, 2,6-di-t-butyl 4-methylphenol, 2,6 di-t-butyl-p- Cresol, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4'-thiobis (3-methyl6-t-butylphenol, 4,4'-butylidenebis (3-methyl-6-t -Butylphenol), stearyl-β (3,5-di-4-butyl4-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-tert-butyl-4-hydroxyphenyl) propionate, tetrakis [methylene-3 (3 ', 5'-di-tert-butyl-4) '-Hydroxyphenyl) propionate] methane, etc. Sulfuric dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, laurylstearylthiodipropionate, distearyl-3'-thiodipro Pionates, ditridecyl-3,3'-thiodipropionate, etc. Phosphorus-based trinonylphenyl phosphite, triphenyl phosphite, etc. Particularly, 2,6-di-tbutyl-p-cresol (hereinafter BHT)
And low volatility high molecular weight phenolic antioxidants (trade names lreganox1010, Ionox330, Topanol CA, etc.) and one or more of dilaurylthiodipropionate, distearylthiodipropionate, dialkisphosphate, etc. ,
It is particularly effective to use two or more of them.

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 light-shielding substance is for ensuring light-shielding properties.
The content of the light-shielding substance is 0.01% by weight or more, preferably
It is 0.03 to 30% by weight, particularly preferably 0.05 to 6.0% by weight. When the content is less than 0.01% by weight, the effect of improving the physical strength is small, and the light-shielding property cannot be secured. When the content of carbon black exceeds 30% by weight, it is difficult to secure physical strength and photographic performance.

The light-shielding substance refers to a substance that can be kneaded or dispersed in each layer and does not transmit visible light, ultraviolet light, and the like. Examples of the light-shielding substance that can be used in the present invention include various carbon blacks, graphite, iron oxide, zinc oxide, titanium oxide, clay, aluminum powder, aluminum paste, calcium carbonate, mica, barium sulfate, talc, cadmium pigments, and valves. Pattern, cobalt blue, copper phthalocyanine pigment,
Monoazo or polyazo pigments, organic pigments such as aniline black, and inorganic pigments are exemplified.

It is also preferable to mix two or more light-shielding substances according to required characteristics. The average particle diameter even if the preferred packaging material for photosensitive materials that the following carbon black 200mμ containing photosensitive unit area of the material for injection-molded articles (m ²⁾ per ^{0.5g / m 2 ~50g / m 2} . On the other hand, among these carbon blacks, those having a pH of 5 to 9 and an average particle diameter of 10 to 120 mμ are preferable, and furnace carbon black having a pH of 6 to 9 and an average particle diameter of 50 mμ or less is particularly preferable. By using such a material having a pH and a particle size, the occurrence of fog is reduced, the occurrence of increase / decrease in photosensitivity is reduced, the light-shielding ability is large, and carbon black lump and fish eyes are hardly generated. Injection molded articles for photographic photosensitive materials having several advantages such as improvement in physical strength and appearance can be obtained.

There are various forms in which the light-shielding substance is blended, but the masterbatch method is preferred from the viewpoints of cost reduction, prevention of workplace contamination, and the like.

Next to the carbon black, a metal powder that is preferable as a light-shielding substance will be described. This metal powder is a light-reflective light-shielding substance that gives a silver-colored, high-product-value appearance, and is excellent in many aspects such as moisture-proof, light-shielding, antistatic, heat-proofing under sunlight, and gas-barrier properties. I have.

As the metal powder, a material obtained by kneading a substance obtained by removing a low volatile substance from aluminum powder or aluminum paste into a thermoplastic resin is particularly preferable.

Here, aluminum paste is used as a grinding medium such as mineral spirit and a small amount of grinding aid such as stearic acid or oleic acid when producing aluminum powder by a known method such as a ball mill method, a stamp mill method, or an atomizing method. It is made into a paste in the presence of higher fatty acids, fatty acid amides, fatty acid metal salts and the like. In the present invention, the aluminum paste and a polyolefin thermoplastic resin (various polypropylene resins, various polyethylene resins, EVA resins, EEA resins, etc.) are heated and kneaded, and low volatile substances (pulverizing media, such as mineral spirits having a strong odor, are mainly used).
Is removed with a heat and / or vacuum pump or the like and used as an aluminum paste compound resin or an aluminum paste masterbatch resin.

In particular, it is preferable to use the resin as an aluminum paste mauter batch resin in order to eliminate adverse effects and odor on photographic light-sensitive materials. For example, even if the mineral spirit content in the master batch resin containing 40% by weight of aluminum paste is 1.0% by weight, if the concentration of aluminum paste in the resin composition is adjusted to 2% by weight, the aluminum paste master batch 1 19 parts by weight of natural resin will be kneaded with respect to parts by weight, and mineral spirit content will be removed as a gas during injection molding in the resin composition, so that the mineral spirit content is 0.
05% by weight or less. As a result, there is no adverse effect on the photographic light-sensitive material and the odor is reduced.

Aluminum powder is obtained by pulverizing molten aluminum into powder by atomizing, granulating, rotating disk dropping, or evaporating, and flakes by pulverizing aluminum foil by ball milling or stamp milling. including. Since the aluminum powder alone is unstable, various known treatments are performed to coat the surface of the aluminum powder with a higher fatty acid or a higher fatty acid compound to make it inert.

The resin composition containing the essential polypropylene resin, the L-LDPE resin, the lubricant, the antioxidant, and the light-shielding substance may contain a nucleating agent to improve rigidity, injection moldability, and molding. It is preferable in terms of reduction of failure, improvement of wear resistance, improvement of heat resistance, and the like.

In addition, the resin composition for producing the injection molded article for photographic light-sensitive materials of the present invention may further contain various known thermoplastic resins and known additives that meet the required characteristics.

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

(Types of additives) (Typical examples) (1) Plasticizer; phthalate ester, grill ester, fatty acid ester, phosphate ester, etc. (2) Stabilizer: lead, cadmium, zinc, alkaline earth (3) Antistatic agents; cationic surfactants, anionic surfactants, nonionic surfactants, surfactants, various carbon blacks, metal powders, graphite, etc. (4) ) Flame retardants; phosphoric esters, halogenated phosphoric esters, halides, inorganic substances, phosphorus-containing polyols, etc. (5) Fillers: alumina, kaolin, clay, calcium carbonate, mica, talc, titanium oxide, silica, etc. (6) Reinforcing agent; glass roving, metal fiber, glass fiber, glass milled fiber, carbon fiber, etc. (7) Coloring agent; inorganic pigment (Al, Fe ₂ O ₃ , TiO ₂ , ZnO, CdS
Etc.), organic pigments (carbon black, dyes, etc.) (8) foaming agents; inorganic foaming agents, (ammonia carbonate, sodium bicarbonate), organic foaming agents (nitrone, azo), etc. (9) vulcanizing agents; vulcanizing (10) Deterioration inhibitors; UV absorbers, antioxidants, metal deactivators, peroxide decomposers, etc. (11) Lubricants; paraffin, wax, fatty acid,
Fatty acid amides, silicones, esters, higher alcohols, etc. (12) Antiblocking agents; silica, diatomaceous earth, talc, calcium silicate, aluminum silicate, calculated magnesium, calcium carbonate, higher fatty acid polyvinyl esters, etc. (13) Coupling agents Silane-based, titanate-based, chromium-based, aluminum-based, etc. (14) Various thermoplastic resins, rubbers, etc. In addition, other chlorine absorbents, coloring dyes, etc. can also be added.

The application of the resin composition of the present invention is an injection molded article for a photographic photosensitive material. For example, it is suitable for color photographic paper (for minilabs, etc.), microfilm, computer-printed photographic paper, computer-printed photographic film, COM (computer output microfilm) film, light-shielding containers for direct positive photographic paper, and the like. It is also used for container components such as spools and cassettes.

Further, the injection molding of the injection molded product for a photographic photosensitive material of the present invention includes vacuum injection molding in a mold.

[Action]

The resin composition for producing the injection-molded product for a photographic light-sensitive material of the present invention increases physical strength, improves dimensional accuracy,
Katsuhiken marks, warpage, weld lines, short shots, etc. are reduced.

〔Example〕

Invention product I The resin composition for packaging photographic light-sensitive materials of the invention product I has an MI of
40 g / 10 min, a flexural modulus of 11500kg / cm ^2, an Izod impact strength of 4.5 kg · cm / cm ^2, amount of propylene Rockwell hardness 90R 96.5 wt%, a propylene-ethylene ethylene content consists of 3.5 wt% 55% by weight of polypropylene resin, which is a randan copolymer resin, MI is 18g / 10min, density is 0.919g
/ cm ^3, Olsen rigidity 2200 kg / cm ^2, and 44.1 wt% L-LDPE resin is an ethylene photopolymer resin shore hardness 50D of ethylene and 4-methylpentene-1, as an antioxidant
0.2% by weight of BHT, 0.2% by weight of oleamide as a lubricant, 0.2% by weight of 1,3,2,4-di (methylbenzylidene) sorbitol as a nucleating agent, and 0.5 carbon black of furnace type as a light-shielding substance % By weight.

Inventive Product II The resin composition for producing the injection molded product for photographic photosensitive materials of Inventive Product II comprises the same propylene / ethylene random copolymer resin as in Inventive Product I 55% by weight, and MI of 10 g / Ten
40% by weight of L-LDPE resin which is an ethylene copolymer resin of ethylene and 4-methylpentene-1 having a density of 0.925 g / cm ³ , an Olsen stiffness of 2500 kg / cm ² and a Shore hardness of 52D, and an antioxidant 0.2% by weight of BHT, 0.2% by weight of oleamide as a lubricant, 0.3% by weight of furnace type carbon black and 4.3% of calcium carbonate as light-shielding substances
% By weight.

Inventive Product III The resin composition for producing the injection molded product for photographic photosensitive materials of Inventive Product III has an MI of 12 g / 10 as an L-LDPE resin.
Product II of the present invention except that L-LDPE resin which is an ethylene / butene-1 ethylene copolymer resin having a density of 0.920 g / cm ³ , an Olsen stiffness of 2500 kg / cm ² and a Shore hardness of 50D is used.
Is the same as

Comparative product I In comparative product I, carbon black was used as a light-shielding substance.
It comprises the same polypropylene resin as the product I of the present invention containing 5% by weight.

Comparative product II In comparative product II, carbon black was used as a light-shielding substance.
It consists of the same L-LDPE resin as the product I of the present invention containing 5% by weight.

Conventional product I Conventional product I contains carbon black as a light-shielding substance.
It consists of an impact-resistant polystyrene resin containing 5% by weight.

As a molded product, an end cap for a photosensitive band container shown in FIG. 2 was formed by an injection molding method.

 The experimental results are shown in Table 1.

[Effects of the Invention] The resin composition for producing the injection molded article for photographic light-sensitive materials of the present invention is inexpensive, has high physical strength, particularly high drop strength, low molding shrinkage, sink marks, warpage, and weld lines. There are few molding failures such as short shots and gate residues, and the solvent resistance, abrasion resistance and appearance are excellent, and the injection molding cycle time can be shortened.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a photosensitive band container formed by using a resin composition for producing an injection molded article for a photographic photosensitive material of the present invention, and FIG. FIGS. 3 and 4 are a plan view and a side view of the other end cap, respectively. 1 ... tubular part, 2 ... end cap, 6 ... core

Claims (1)

(57) [Claims] 1. A melt index of 10 to 60 g / 10 minutes, a flexural modulus of 8000 kg / cm ² or more, and an Izod impact strength of 2.0 kg.
・ Cm / cm ² or more, Rockwell hardness 70R or more, molecular weight distribution 1.5 to 8 polypropylene resin with 70 to 30% by weight,
Melt index 3-50g / 10min, density 0.910-0.9
35 g / cm ³ , Olsen stiffness of 1500 kg / cm ² or more, Shore hardness of 40 D or more, molecular weight distribution of 1.5 to 8 30 to 70% by weight of linear low density polyethylene resin and lubricant of 0.01 to 2% by weight
And 0.01 to 1.0% by weight of an antioxidant and 0.0
Resin composition for producing injection-molded article for photographic photosensitive material, comprising 1 to 30% by weight