JPS60238346A - Light-screening styrene resin film or sheet - Google Patents

Abstract

PURPOSE:The titled sheets or films that contain a specific inorganic filler in a platelet form and powdery titanium oxide, thus having white appearance and preventing food inside from deteriorating by oxidation, when the sheets or films are used as a sealer, even in the presence of oxygen, because they have excellent light-screening effect. CONSTITUTION:A styrene resin is combined with an inorganic filler in a platelet shape and titanium oxide whose particle diameters are more than 1mu on the average in a total amount of less than 35wt% and the composition is made into sheets or films. The amount of the inorganic filler added is 1-20wt%, preferably 1-15wt%, and the powdery titanium oxide is 3-15wt% based on the resin. The styrene resin used is preferably a high-impact resin combined with a copolymeric elastomer from a vinyl aromatic compound and a conjugated diene.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a light-shielding styrenic resin film or sheet,
The present invention particularly relates to a light-shielding styrenic resin film or sheet suitable for aseptic packaging of foods containing unsaturated fatty acids.

(Prior Art) In recent years, so-called aseptic packaging systems have been adopted in which synthetic resin containers are filled with food under aseptic conditions. This is useful as a means to prevent food from spoiling due to microorganisms and extend its shelf life. When sealed, the oxygen present inside the container can oxidize the food, shortening its shelf life.

To prevent this, for example, there are methods of filling a synthetic resin container using an oxygen-blocking packaging material with an inert gas or creating a vacuum, but both methods are economically problematic.

Generally, the oxygen present in a synthetic resin container is affected by light from outside the container, which accelerates the oxidation reaction, but in order to prevent this, a synthetic resin sheet mixed with carmen black is used. , it becomes possible to block light. However, it cannot be used for food-to-packaging because of its poor appearance.

The purpose of the present invention is to solve these drawbacks, and the gist of the present invention is to use a styrene resin film or sheet made of styrene resin containing an inorganic filler and titanium oxide, so that the inside of the container can be The purpose of the present invention is to provide a packaging material that prevents oxidative deterioration of foods even in the presence of oxygen and has a white appearance.

(Means for solving the problem) That is, the present invention provides styrene resin with an average particle diameter of 1 μm.
Total amount of the above plate-shaped inorganic filler and titanium oxide powder 65
This relates to a light-shielding styrenic resin film or sheet containing at most % by weight.

The present invention will be explained in more detail below.

Examples of the plate-shaped inorganic filler used in the present invention include clay, talc, aluminum hydroxide, mica, basic calcium carbonate, etc., but any filler that exhibits plate-shaped crystals may be used. However, spindle-shaped inorganic fillers such as calcium carbonate cannot achieve the object of the present invention even when used in combination with titanium oxide.

Furthermore, even when using a plate-shaped inorganic filler, it is necessary that the average particle size thereof is at least 1 μm or more; anything smaller than this has little effect.

In the present invention, the average particle diameter refers to a particle size distribution (weight%) of 50
% or more.

Even if such a plate-shaped inorganic filler is used alone, it has no light blocking effect at all, but it is effective when used in combination with titanium oxide, and titanium oxide can be either rutile type or anatase type. There isn't. ! There are no particular restrictions on the particle size, and any commercially available powder is sufficient.

Next, regarding the amount added to these styrene resins,
The inorganic filler is on the inside of the entire styrenic resin, and is
The content may be 20% by weight, preferably 1 to 15% by weight.

The minimum filling amount for obtaining sufficient light-shielding properties varies depending on the type of filler, particle size, etc., but generally 1% by weight or more is effective. Moreover, if it exceeds 20% by weight, it will be difficult to form into films or sheets, and the color tone will not be white.

Regarding the amount of titanium oxide, it should be 3 to 15% by weight on the inside of the entire styrene resin. If it is less than 6% by weight, there will be no light-shielding effect, and if it exceeds 15% by weight, it will cause damage to the structure of the film or sheet. Unfavorable due to problems. Therefore, the total amount added to the styrene resin is preferably 65% by weight or less. Furthermore, from an economic point of view, a filler may be added.

Furthermore, when blending the filler with the styrene resin, it is effective to add a dispersant such as a fatty acid metal soap.

The styrenic resin used in the present invention includes, for example, styrene-
Butadiene graft copolymer resin, mixture of this resin and general-purpose styrene resin, methylene-methyl methacrylate-citadiene copolymer resin, styrene-butadiene block copolymer resin, general-use styrene resin and styrene-citadiene block copolymer Mixture with resin, styrene-α-
It contains a resin whose main component is styrene, such as a methylstyrene copolymer resin or a styrene-butadiene acrylonitrile copolymer resin, or a small amount of a rubbery polymer containing styrene.

A so-called No. 1 impact styrene resin, which is obtained by graft polymerizing styrene onto a diystomer or a butadiene elastomer, is preferably added with a copolymerized diystomer of a vinyl aromatic compound and a conjugated diene compound, from the viewpoint of impact resistance.

Furthermore, to explain the block copolymer distomer of a vinyl aromatic compound and a conjugated diene compound, it may have a complete block structure of block A of the vinyl aromatic compound and block B of the conjugated diene compound, , any one having a so-called tapered r-block structure containing these random copolymer parts may be used.

Examples of the vinyl aromatic compound include styrene, α-methylstyrene, and vinyltoluene, and examples of the conjugated diene compound include zotadie and isozolene. Among these block copolymerized di-stomers, those containing 50% by weight or more of the conjugated diene compound are preferred, and 60 to 75% by weight di-stomers are particularly preferred.

Further, the amount of the block copolymerized distomer added is preferably 6 to 6% by weight, although it is sufficient to add 1 to 10% by weight on the inside based on the entire styrene resin.

If it is less than 1% by weight, the effect is the same as when it is not added, and if it exceeds 10% by weight, the impact strength does not improve and, on the contrary, the film or sheet tends to become soft.

Next, if the product is packaged with a film or sheet made of a styrene-based resin containing a plate-shaped inorganic filler and titanium oxide, the contents may be, for example, the initial peroxide value (p, o, Even when using soybean oil with V) of 0.3 meqAg and storing it in a fluorescent knife for 5 days, less than about 1.0 meυ odor can be produced in p, o, and v, so it can be used as is.
However, it can be used as a light-shielding sheet. Furthermore, when used in a laminated manner with a film or sheet of polyethylene, polypropylene, vinylidene chloride, saponified ethylene-vinyl acetate copolymer, etc., it becomes a light-shielding packaging material with oil resistance and sparring properties, making it suitable for food packaging.

(Example) The present invention will be further explained below with reference to Examples.

Example 1 Varying amounts of inorganic filler and titanium oxide were mixed with impact-resistant styrene resin, and sheets with a thickness of 0.6 mm were molded by a conventional method.

This sheet was thermoformed into a container with a capacity of 20 cc, and 15 cc of soybean oil was placed in the container, and aluminum foil was used as a lid material, and the container was sealed. The peroxide value of the soybean oil was measured after the fluorescent coating was stored for 5 days.

These conditions and results are shown in Table 1.

The styrene resin and compounding agents used in the experiment are as follows.

Styrenic resin 1 (α1 to 17 and 22 to 26 are the product names [Denka Styrol H-E-4J (manufactured by Ki Kagaku Kogyo ■); Nos. 18 to 21 are the product names "Denka Styrol TPJ (manufactured by Denki Kagaku Kogyo ■) Oxidation Titanium Product name [Tie Bake 0R-604 (Ishihara Sangyo ■#) Rishi - Product name rTC-400J Particle size 4.7μProduct name rTC-80ONJ Particle size 0.7μ (manufactured by Toyo Kasei ■) Taruri Product name "1 Calcium Carbonate Light Calcium (manufactured by Takehara Chemical Co., Ltd.) No. 1 Talc (manufactured by Takehara Chemical Co., Ltd.) Table 1 Example 2 A container with a depth of 70 mm and 50 mm was thermoformed from a sheet obtained using the formulation shown in Table 2. After filling the container with water and covering it with aluminum foil, the container was dropped onto concrete at 0° C., and the height at which the container would break by 50 cm was determined.

The clay used was manufactured by Toyo Kasei ■, product name rTc-
The 400J styrene-citadiene block copolymer elastomer (abbreviated as S-E) was manufactured by Mukasei Kogyo ■ under the trade name "Tuffrene", and the others used were those of Example 1.

These conditions and results are shown in Table 2.

*P, O, V (peracid value) is calculated by adding the sample oil to a mixed solution of acetic acid and chloroform, adding potash, and then adding 100% of the sample oil.
Titrate with sodium N-thiosulfate.

(Effects of the invention) The packaging material of the product of the present invention is characterized by the combination of a plate-shaped inorganic filler and titanium oxide, and by using this as a sterile packaging material, it is possible to prevent the effects of light from affecting food products. It consists of an excellent film or sheet that greatly extends the lifespan of foods and gives them a white appearance even in the presence of oxygen.

Patent applicant Denki Kagaku Kogyo Co., Ltd.

Claims (1)

[Claims] A light-shielding styrene resin film or sheet comprising a styrene resin containing a plate-shaped inorganic filler with an average particle size of 1 μm or more and titanium oxide powder in a total amount of 35 weight or less.