JPH04342730A - Production of master batch for packing material for photographic sensitized material and production of molding resin using the same master batch - Google Patents

Abstract

PURPOSE:To obtain a master batch for a packing material for packaging a photographic sensitized material having improved light screening properties by blending a polystyrene resin with carbon black, a specific dispersant and a lubricant, melting and kneading. CONSTITUTION:(A) A polystyrene resin for common use and an impact-resistant polystyrene resin are mixed with (B) carbon black, (C) 10-45wt.% based on the component B of a glycerol fatty acid ester as a dispersant and (D) 10-45wt.% based on the component B of a bis-fatty acid amide or stearic acid as a lubricant by a twin-cylinder mixer 6 at the same time to give a carbon black- containing polystyrene resin. Then the carbon black-containing polystyrene resin is fed to a kneading extruder 7, melted and kneaded to give a master batch for a packing material for photographic sensitized material having more improved dispersibility of carbon black.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a masterbatch for packaging materials for photographic light-sensitive materials such as photographic film cartridges, and a method for producing a molding resin using this masterbatch.

0002

BACKGROUND OF THE INVENTION Light-shielding properties are an important element in photographic materials. For example, photographic film is generally stored and used wound on a cartridge spool. The most important property that this spool should have is light-shielding properties. If the light-shielding properties of the spool are insufficient, the film will be exposed to external light, causing fog. Conventionally, in order to ensure the light-shielding properties of the spool, carbon black as a light-shielding substance has been mixed and dispersed in the base resin of the spool. Therefore, the quality of the dispersibility of carbon black into the base resin greatly affects the maintenance of film performance.

On the other hand, polystyrene resins are preferably used as base resins for packaging materials for photographic materials from the viewpoint of appearance, dimensional stability, strength, heat resistance, and the like. In this case, the polystyrene resin is a blend of high impact polystyrene resin (hereinafter referred to as "HIPS"), which is obtained by graft polymerizing synthetic rubber such as butadiene rubber to styrene monomer, and general purpose polystyrene resin (hereinafter referred to as "GPPS"). is preferably used. If only GPPS is used, the product is hard and brittle, so if a protrusion occurs during demolding, the protrusion may be damaged during automatic transport to the film winding process, or easily damaged if dropped. , HIPS are used in combination.

[0004] Conventionally, as a method for manufacturing spools using polystyrene resin, instead of the old method of melting and kneading GPPS, HIPS, and carbon black, for example, Japanese Patent Application Laid-Open No. 63-318553 discloses HIP.
Carbon black is mixed with S in a Banbury mixer, and this carbon-containing masterbatch pellet and H
A method is disclosed in which IPS and silicone oil are kneaded to obtain silicone-containing masterbatch pellets, and this is mixed with GPPS before a molding machine. In addition, JP-A No. 1-182327 discloses GPP with high melt flow.
Carbon black masterbatch pellets in which carbon black is dispersed in S in the presence of zinc stearate as a dispersant are melt-kneaded with GPPS with a low melt flow and silicone, and then this is mixed with GPPS with a low melt flow. A method of mixing before the molding machine is shown. However, in the prior laws described in these publications,
Dispersion of carbon black is carried out exclusively with a single dispersant, and when silicone is used as a spool, it is used exclusively as a lubricant for the film, so it is not assumed that a dispersant and a lubricant are added at the same time. .

[0005]

[Problems to be Solved by the Invention] However, although each of the above-mentioned prior methods is superior in that the dispersibility of carbon black can be improved by obtaining a color masterbatch compared to the conventional method, it is not always possible to improve the dispersibility of carbon black. Black dispersibility is not good. Furthermore, the techniques described in both publications have two batch processes, one during mixing and one during melt-kneading, and are not continuous processes, requiring complicated operations.

Generally, in order to further improve the dispersibility of carbon black, as in the method of the present invention described below, a dispersant and a lubricant are simultaneously kneaded in the melt-kneading process, thereby dispersing the particles on the segments between the polymers. In contrast, in the conventional method, the dispersant and lubricant are added separately, and the carbon black of the dispersant on the segment can be promoted. The effect of promoting adsorption to the particle surface cannot be expected.

Accordingly, an object of the present invention is to further improve the dispersibility of carbon black to enhance the light-shielding properties of a resin for packaging materials for photographic light-sensitive materials.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the method for producing a masterbatch for packaging materials for photographic materials of the present invention involves dispersing carbon black in a general polystyrene resin and an impact-resistant polystyrene resin. In particular, 10 to 45 wt% glycerin fatty acid ester, based on carbon black, and 10 to 45 wt% bis fatty acid amide or 10 to 45 wt%, based on carbon black.
It is characterized in that at least one of stearic acid (5 wt %) is simultaneously added, mixed, and melt-kneaded.

Further, in the method for producing a molding resin for packaging materials for photographic light-sensitive materials according to the present invention, when carbon black is dispersed in a general polystyrene resin and an impact-resistant polystyrene resin, the carbon black is 45w
A step of simultaneously adding and mixing t% of glycerin fatty acid ester and at least one of 10 to 45 wt% of bis fatty acid amide or 10 to 45 wt% of stearic acid to carbon black: Carbon black obtained by this step A step of melting and kneading the containing polystyrene resin to obtain color masterbatch pellets: A step of mixing the color masterbatch pellets with a general-purpose polystyrene resin and a high-impact polystyrene resin before or on the molding machine: It is characterized by including.

(Preferred Embodiment) The polystyrene resin used in the present invention may be a single HIPS or GPPS, but an impact-resistant polystyrene resin that is a mixture of both is preferred from the standpoint of use as a packaging material. This impact-resistant polystyrene resin includes, for example, conjugated 1,3 diene polymers such as butadiene, isoprene, chloroprene, etc.
It is a polystyrene resin obtained by graft polymerizing one or more rubbers such as styrene-butadiene copolymer rubber and butyl rubber to a styrene monomer. This resin is
It has higher impact resistance than general polystyrene resin made by polymerizing styrene monomers. When using HIPS and GPPS together, the weight ratio is HIPS:GPPS
is preferably 1:1 to 1:2.

[0011] Carbon black is dispersed in polystyrene resin to ensure light-shielding properties. This carbon black has a pH of 5.
~9, graphite with an average particle size of 10 to 120 μm,
Lamp black, acetylene black, bone black, furnace black, channel black, thermal black, etc. can be used. Carbon black is preferably added in an amount of 0.2 to 2% by weight in the total composition.

The carbon black is dispersed in the polystyrene resin in the presence of both a dispersant and a lubricant. According to the present invention, when carbon black is dispersed in polystyrene resin, when both a dispersant and a lubricant are added and kneaded, the carbon particles trapped on the segments between the polymers are released from the polymer segments by the lubricant, and the carbon This makes the particles coarser and further promotes the adsorption of the dispersant onto the surface of the carbon particles, resulting in extremely excellent dispersibility.

[0013] Thus, the polystyrene resin, carbon black, dispersant, and lubricant are mixed. This mixing can be carried out using a Banbury mixer, a mixing roll, or the like.

The mixture is melt-kneaded using a known melt-kneader, and then made into a spherical, cylindrical or prismatic shape with a diameter or side of 2 to 5 mm, for example, using a pelletizer to obtain color masterbatch pellets.

[0015] The color masterbatch pellets may be mixed with other suitable polystyrene resins or preferably with HIP.
S and GPPS are mixed before a molding machine and molded into a predetermined shape, for example, a spool shape.

The shape of the spool is as shown in FIGS. 4 and 5, and a slit 3 into which the tongue piece 2a of the film 2 can be inserted is formed at approximately the center of the winding shaft 1. A locking pawl 4 capable of locking the hole 2b of the tongue piece 2a of the film 2 is formed on the inner wall surface, and the film 2 is secured to the locking pawl 4. Such a spool is manufactured by injection molding, and therefore, a resin injection part called a gate is formed at an appropriate position such as the short hub part 5 or the holding rib part 6 of the spool. The resin injection part is slightly concave to prevent the remaining gate from coming out from the concave part of the injection part. For example, when providing a gate on the short hub part, the width is 1 mm and the depth is 0.
It has a recess of about 5 mm.

In the present invention, glycerin fatty acid ester is used as a dispersant, and bis fatty acid amide or stearic acid is used as a lubricant. Furthermore, glycerin monostearate is preferred as the glycerin fatty acid ester. Ethylene bisamide is preferable as the bis fatty acid amide. Both bis fatty acid amide and stearic acid can also be used together as a lubricant.

[0018] In general, a dispersant enters the gaps between the constituent particles of various powders and adsorbs to the surface of the target particles, promoting mutual dissociation of the particles and preventing re-agglomeration. In order for such a dispersant to be sufficiently adsorbed onto the particles, it is necessary to create many gaps in the particle mass so that the dispersant can easily enter. For example, when polymer particles are present, a lubricant (also referred to as an internal lubricant, a dispersion aid, etc.) is used to loosen adjacent segments of polymer chains and increase gaps, thereby making it easier for the dispersant to enter. According to the findings of the present inventors, it has been found that glycerin fatty acid ester is effective as the dispersant for carbon black, and that bis fatty acid amide or stearic acid is optimal as the lubricant. On the other hand, zinc stearate as a dispersant and silicone as a lubricant are not effective.

The blending ratio of dispersants and the like will be explained. The constituent particles of carbon black have a specific surface area of 800 to 10
Since the particles are extremely fine, on the order of 00 m2/g (BET value), a considerable amount of dispersant is also required to be adsorbed onto the surface. However, if too much dispersant is added, it will not be completely adsorbed onto the surface of the carbon particles;
A large amount of it remains on the polymer that serves as the base material of the film, and this causes a decrease in the viscosity of the polymer. If the viscosity of the base polymer decreases, when carbon is dispersed in a polymer or the like in a kneader, shearing force cannot be effectively transmitted to the dispersion system, resulting in a decrease in kneading efficiency. On the other hand, if the amount of the dispersant is too small, it will not be sufficiently adsorbed onto the surface of the carbon particles and the dispersibility of carbon will decrease. Therefore, the present inventors conducted extensive studies on the range of blending amounts of dispersants, etc., and found that glycerin fatty acid ester, which is a dispersant, and bis fatty acid amide or stearic acid, which are lubricants, each contained 0.1% of each in the total resin composition. ~2.0
It has been found that it is desirable to contain it by weight%.

[0020] Glycerin fatty acid ester as a dispersant, bis fatty acid amide or stearic acid as a lubricant can be contained in an amount of 10 to 45 wt%, respectively, based on the carbon black in the kneading process, as shown in the examples below. This is necessary in order to further improve dispersibility. Thus, due to the improved dispersibility of carbon black,
The spool as a finished product has excellent light-shielding properties. The weight ratio of dispersant and lubricant is 1:0.7 to 1.3.
is preferred.

[0021]

[Example] Next, the effects of the present invention will be clarified by examples. The resins used in this example are as follows. GPPS (Asahi Kasei “666R”)…41% HIPS
(Asahi Kasei Co., Ltd. "408")...20% carbon black (Mitsubishi Kasei Co., Ltd. "#950")...25% Glycerin fatty acid ester (dispersant)...7% (Glycerin monostearate, Riken Vitamin Co., Ltd. "Rikemar 100") ) Bis fatty acid amide (lubricant)...7% (ethylene bisamide, NOF Corporation "Alflo H50T")
”) During manufacturing, as shown in Figure 1, GPPS1, HI
PS2, carbon black C. B3 and glycerin fatty acid ester as a dispersant G. E4 and bis fatty acid amide as lubricant C. A5 was put into a V-blender 6, thoroughly mixed, put into a melt-kneading extruder 7, melt-kneaded, and hot-cut with a pelletizer 8 (diameter 2 mm, length 3 mm) to create a carbon black-containing color masterbatch. Furthermore, the masterbatch is further processed in the molding machine 9.
It was mixed with PS1 and HIPS2 to form a spool for 135 mm film. Further, the kneading extruder and molding machine used in this example will be described below together with their operating conditions. <Kneading extruder> Model: "PCM-30" manufactured by Ikegai Iron Works Rotation speed: 150 rpm Melting temperature: 220°C Processing amount: 5.0 kg/H <Molding machine> Model: "Nestal (150 t)" manufactured by Sumitomo Heavy Industries Screw diameter: 45 mm Melting temperature: 230° C. Molding cycle: 20 (sec) Spool shape: 135 mm Spool for film Next, the blending amounts of the dispersant and lubricant in the present invention will be explained. Figure 2 shows the amount of light transmitted according to the mixing ratio (additive/carbon black) of glycerin monostearate (dispersant) and bis fatty acid amide or stearic acid (lubricant) as an example of glycerin fatty acid ester. This shows the results. As is clear from this figure, the blending amount of the additive according to the present invention is 10 to 4
At 5 wt%, the amount of light transmitted is the smallest and the light shielding property is good.

On the other hand, as a comparative example, the results of using zinc stearate as a dispersant and ethylene bisamide as a lubricant are shown in FIG. In this comparative example, as shown in the figure, the amount of light transmission is largely the same in any range,
It can be seen that the light shielding properties of the spool are not good.

[0023]

As described above, according to the present invention, the dispersibility of carbon black can be improved, and the light-shielding properties of the spool can be improved. Moreover, the spool resin can be manufactured by a continuous process.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing a molding method in an example.

FIG. 2 is a graph showing the results of the amount of light transmission in Examples.

FIG. 3 is a graph showing the results of the amount of light transmission in a comparative example.

FIG. 4 is a perspective view of the spool shown in relation to the film.

FIG. 5 is a front view of the spool.

Claims (2)

[Claims] Claim 1: When dispersing carbon black in general polystyrene resin and impact-resistant polystyrene resin,
10-45 wt% glycerin fatty acid ester based on carbon black and 10-45 wt% bis fatty acid amide or 10-45 wt% based on carbon black
1. A method for producing a masterbatch for packaging materials for photographic materials, which comprises simultaneously adding at least one of stearic acids in an amount of % by weight, mixing, and melt-kneading. [Claim 2] When dispersing carbon black in general-purpose polystyrene resin and impact-resistant polystyrene resin,
10-45 wt% glycerin fatty acid ester based on carbon black and 10-45 wt% bis fatty acid amide or 10-45 wt% based on carbon black
A step of simultaneously adding and mixing at least one of wt% stearic acid; A step of melting and kneading the carbon black-containing polystyrene resin obtained in this step to obtain color masterbatch pellets; and a step of obtaining color masterbatch pellets. 1. A method for producing a molding resin for a packaging material for photographic light-sensitive materials, comprising: mixing a general-purpose polystyrene resin and an impact-resistant polystyrene resin before or on a molding machine.