JPS62177030A - Production of sheet made of colored thermoplastic resin - Google Patents

Abstract

PURPOSE:The titled sheet useful as a substrate for photographic films such as X-ray films, colored in a uniform concentration, having high quality free from concentration unevenness, obtained by blending thermoplastic resin chips with dye fine powder in a specific ratio, molding the blend by extrusion and subjecting it to biaxial orientation. CONSTITUTION:(A) thermoplastic resin chips are blended with (B) dye fine powder in such a way that total surface area SIGMAA of the whole chips of average surface area A per thermoplastic resin chip and total dye fine powder area SIGMAB of average surface area B per fine particle of the dye fine powder have correlation shown by the formula SIGMAB<=3SIGMAA and molded by extrusion. Then, the molded article is subjected to biaxial orientation to give the aimed sheet made of colored thermoplastic resin. Since the prepared sheet has no excess dye fine powder based on the thermoplastic resin chips, it causes neither isolation phenomenon nor aggregation of dye and is colored in uniform concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a colored thermoplastic resin sheet used as a support for photographic film such as X-ray film.

[Technology background]

For example, supports for photographic films such as X-ray films may be required to be colored with, for example, blue-based dye powder in order to make images easier to see during diagnosis using X-ray films. A colored thermoplastic resin sheet used as such a support is usually produced by mixing thermoplastic resin chips and fine dye powder, extrusion molding, and then biaxial stretching.

As the thermoplastic resin chips, angular or cylindrical pieces of several mm in size are usually used, and as the dye fine powder, fine particles with an average particle size of about 15 to 30 U are usually used. . By mixing fine dye powder with this thermoplastic resin chip, the fine particles of dye adhere to the surface of each thermoplastic resin chip, so by extruding them into a sheet shape and further biaxially stretching, A colored thermoplastic resin sheet is obtained.

[Problem that the invention seeks to solve]

However, in order to obtain high quality colored thermoplastic resin sheets used as supports for photographic films, it is necessary that the entire sheet be colored with a uniform density.

However, depending on the mixing conditions of the thermoplastic resin chips and the fine dye powder, there is a problem in that the resulting colored thermoplastic resin sheet may have uneven density, resulting in poor quality.

That is, when the ratio of the dye fine powder to the thermoplastic resin chip is excessive, the dye fine powder exists in a free state without being able to adhere to the thermoplastic resin chip (hereinafter also referred to as "freedom phenomenon"). ), and furthermore, there are cases where this fine dye powder aggregates, and when extrusion molding is performed in such a state, the part where the fine dye powder existed in a free state becomes more concentrated than other parts. There is a problem in that the color density becomes abnormally high, resulting in areas with uneven density.

[Object of the Invention] The present invention was made based on the above-mentioned circumstances, and its object is to provide a manufacturing method capable of obtaining a colored thermoplastic resin sheet colored with a uniform density. There is a particular thing.

[Means for solving problems]

The method for producing a colored thermoplastic resin sheet of the present invention includes a step of mixing thermoplastic resin chips and fine dye powder, extrusion molding, and then biaxially stretching, and one of the thermoplastic resin chips The relationship between the surface area ΣA of the entire chip, where the average surface area per chip is A, and the surface area ΣB of the entire fine dye powder, where B is the average surface area per particle of the fine dye powder, is expressed by the following formula (1 The method is characterized in that the thermoplastic resin chips and the fine dye powder are mixed under conditions that satisfy the following conditions.

Equation (1) ΣB≦3ΣA According to this method, the thermoplastic resin chips and the fine dye powder are mixed at a mixing ratio such that the total surface area of each satisfies a specific condition. All of the fine particles of the dye are not separated and adhere to each of the thermoplastic resin chips, and as a result, it is avoided that the fine particles of the dye powder remain free from the thermoplastic resin chips. In the colored thermoplastic resin sheet, there are no locally high-density areas and the color is uniformly colored.

The present invention will be explained in detail below.

In the present invention, the thermoplastic resin chip and the dye fine powder are divided into a total surface area ΣA of the entire chip when the average surface area of each thermoplastic resin chip is A, and one fine particle of the dye fine powder. The relationship between the surface area ΣB of the entire fine dye powder and the average surface area per unit is B satisfies the above formula +1.1, and the mixture is extruded and then biaxially stretched to form a colored thermoplastic resin. manufactures sheets.

As the thermoplastic resin chip, it is usually possible to use a polyester resin angular or cylindrical small piece of several mm in size. In addition, as dye fine powder,
Fine particle powder having an average particle size of about 15 to 30 μm can be used.

The coloring density of the colored thermoplastic resin sheet is selected to be an appropriate value as necessary in relation to the application, but specifically, it changes depending on the content ratio of the fine dye powder. Therefore, the present inventors have developed a colored thermoplastic resin sheet with a dye fine powder content of, for example, 200 to 300 ppm (heavy M).
In order to obtain a suitable value within the range of , the ratio ΣB/ΣA of the surface area ΣB of the entire fine dye powder to the surface area ΣA of the entire thermoplastic resin chip is varied and mixed. When we conducted an experiment to investigate whether the phenomenon of liberation of fine dye powder occurred, we found that the ratio Σ
It has been found that when the value of B/ΣA exceeds 3, a release phenomenon occurs rapidly. In other words, by mixing the thermoplastic resin chips and the fine dye powder under conditions that satisfy the above formula +11, the entire fine particles of the fine dye powder can be mixed into the thermoplastic resin without causing the release phenomenon of the fine dye powder. It becomes possible to reliably attach it to each chip. In FIG. 1, the release rate on the vertical axis is a value indicating the weight percent of the dye released relative to the input dye.

In order to mix the thermoplastic resin chips and the fine dye powder so as to satisfy the above formula (1), the following procedure may actually be performed.

In other words, when mixing both in a hatch type, the amount of preparation per batch is W (kg), the weight of one thermoplastic resin chip is W3° (kg), and the weight of the entire thermoplastic resin chip is W (kg). The weight is W3゜(kg), fine particles of dye powder 1
The weight of the dye powder is Wbo (kg), and the weight of the entire fine dye powder is Wbo (kg).
,. (kg), and the number of mixed particles of thermoplastic resin chi-nobu and fine dye powder is na.

and nbO, the condition under which the release phenomenon does not occur is nao·A≦3nbo·B from the above formula (1).

Now, if we mix both under the condition that nall' A=2nbo-B, then from this formula, 1'1ao=
2 nbo' (B/A) ..."■.

Also, regarding the amount of preparation per hatch, VJh=
n ao' wao ten n bo' Wbo ”
・It is ■.

The amount of thermoplastic resin chinobu and the amount of fine dye powder per hatch are respectively W, , = naO-W,o , , ,
, ■Wbo= nbo ' Wbo
”,...■.

Therefore, the procedure is to calculate n3° and nbO from equations 0 and 0.
Find W8° and W from the 0 formula and the 0 formula. The thermoplastic resin chips and the fine dye powder may be mixed according to the obtained value.

In addition, when mixing both in a continuous method, if the total amount of preparation per unit time is W + (kg), the following procedure is the same as in the case of a batch method, and the amount of thermoplastic resin chips per unit time is W81. Since the dye fine powder amount Wb+ can be determined, the thermoplastic resin chips and the dye fine powder may be continuously mixed according to the obtained value.

Generally, polyester resin or the like can be suitably used as the thermoplastic resin chip, but it is not limited thereto. Particularly suitable polyester resins are those whose acid component is mainly terephthalic acid and whose alcohol component is mainly ethylene glycol, but may contain other acid components and/or alcohol components. Such other acid components include isophthalic acid,
One or more naphthalene dicarboxylic acids,
Examples of alcohol components include β-hydroxyethoxybenzoic acid, p-hydroxybenzoic acid, adipic acid, and sebacic acid. Other alcohol components include trimethylene glycol, tetramethylene glycol, hexamethylene glycol, and 1,4-cyclohexane. Examples include one or more fatty acids or alicyclic or aromatic dioxy compounds such as dimethatool, and polyalkylene glycols such as polyethylene glycol. Preferred polyester resins are those in which at least 80 mole percent of the repeating structural units are ethylene terephthalate units.

Further, as the fine dye powder, fine powder of anthraquinone dye can generally be used, but it is not limited thereto.

The coloring density of the colored thermoplastic resin sheet is selected to be an appropriate value depending on the application and is not necessarily limited, but generally, the coloring density of the colored thermoplastic resin sheet is 200 to 300 ppm (by weight). The content ratio of the fine dye powder is selected so as to have an appropriate value within the range.

FIG. 2 is an explanatory diagram showing an example of the manufacturing process of a colored thermoplastic resin sheet, in which 11 is a storage tank for thermoplastic resin chips, 12 is a storage tank for recycled chips, 2 is a storage tank for fine dye powder, and 31 is a storage tank for reused chips. and 32 are drying mechanisms, 41 and 42 are mixing mechanisms, 51 and 52 are extrusion molding mechanisms, and 6 is a biaxial stretching mechanism.

In this example, thermoplastic resin chips weighed under conditions that satisfy the above equation (1) are transferred from the storage tank 11 to the drying mechanism 3.
1 and subjected to drying treatment, and then the dried thermoplastic resin chips are supplied to a mixing mechanism 41. At the same time, fine dye powder measured under conditions satisfying the above formula (1) is supplied from the storage tank 2 to the mixing mechanism 41. In the mixing mechanism 41, the thermoplastic resin chips and the fine dye powder are mixed.

The thermoplastic resin chips and dye fine powder mixed in this manner are then supplied to an extrusion molding mechanism 51, where they are heated and melted and extruded to form a sheet body with a thickness of usually several mm. . Then, this sheet body is vertically stretched by a biaxial stretching mechanism 6, and then horizontally stretched,
The thickness is approximately 75 to 175 nm, and the coloring density is 20.
A colored thermoplastic resin sheet having a constant concentration of 0 to 300 ppm (by weight) is obtained.

Further, during the manufacturing process, for example, after extrusion molding, after longitudinal stretching, and after horizontal stretching, unnecessary portions of the sheet body are usually removed, so sheet waste is generated. When such sheet waste is to be reused, for example, the sheet waste is crushed into an appropriate size and used as reusable chips, and the reusable chips are stored in the storage tank 12. Then, the weighed reusable chips from the storage tank 12 are supplied to the drying mechanism 31 together with the thermoplastic resin chips from the storage tank 11 for drying treatment, and then these are supplied to the mixed supply 41 together with the fine dye powder from the storage tank 2. A colored thermoplastic resin sheet is obtained in the same manner.

In addition, when producing a so-called masterbatch whose coloring concentration exceeds the range of 200 to 300 ppm (weight),
The weighed thermoplastic resin chips are fed from the storage tank 11 to another drying mechanism 32 for drying treatment, and then the weighed fine dye powder from the storage tank 2 is fed together with the dried thermoplastic resin chips to another mixing mechanism. 42 and mix them.

Next, these mixtures are passed through the mixing mechanism 41 in the same manner as described above.
A colored thermoplastic resin sheet is obtained by supplying the mixed mixture to the extrusion molding mechanism 51 in the same manner. Alternatively, the mixture from the mixing mechanism 42 may be fed to another dedicated extrusion molding mechanism 52 to obtain a colored thermoplastic resin sheet.

〔Example〕

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

Example 1 Using the apparatus shown in Fig. 2, a thermoplastic resin chip consisting of a small cylindrical piece made of polyester resin with a circle diameter of about 3 mm and a length of about 3 mm, and an anthraquinone dye were prepared. The relationship between the surface area ΣA of the entire thermoplastic resin chip and the surface area ΣB of the entire dye powder is as follows: ΣB=2ΣA The mixture was mixed to satisfy the following conditions, extrusion molded, and then biaxially stretched to produce a colored thermoplastic resin sheet.

When this colored thermoplastic resin sheet was examined for density unevenness, the density unevenness in all parts relative to the set density was as low as 0.2% or less, including measurement error, and was of excellent quality. The density unevenness was measured in the width direction and longitudinal direction of the colored thermoplastic resin sheet using an optical densitometer.

Comparative Example 1 Colored thermoplastics were prepared in the same manner as in Example 1, except that the relationship between the surface area ΣA of the entire thermoplastic resin chip and the surface area ΣB of the entire dye fine powder was mixed under conditions that satisfied ΣB = 3.5ΣA. A resin sheet was manufactured.

When this colored thermoplastic resin sheet was examined for density unevenness in the same manner as in Example 1, the density unevenness was as large as about 10% relative to the set density, and the quality was poor.

In this example, the reason why the density unevenness value (10%) was smaller than the release rate value (14%) is because the dye fine powder was dispersed and averaged to some extent within the extrusion molding mechanism 51. It is believed that there is.

〔Effect of the invention〕

As described above, according to the method for manufacturing a colored thermoplastic resin sheet of the present invention, the thermoplastic resin chips and the fine dye powder are mixed under conditions such that the total surface area of each satisfies a specific relationship. Therefore, all of the fine particles in the dye fine powder are not released and adhere to each thermoplastic resin chip, and as a result, the fine dye powder particles exist in a state where they are free from the thermoplastic resin chips. Therefore, in the colored thermoplastic resin sheet obtained, there are no locally high concentration areas and the coloring is uniformly concentrated, and as a result, it is possible to produce a high quality colored thermoplastic resin sheet. can.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the relationship between the ratio ΣB/ΣA of the surface area ΣB of the entire dye fine powder to the surface area ΣA of the entire thermoplastic resin chip and the release rate of the dye fine powder, and Figure 2 is a manufacturing process. It is an explanatory view showing an example. 11... Storage tank for thermoplastic resin chips 12... Storage tank for recycled chips 2... Storage tank for fine dye powder 31, 32... Drying mechanism 4L42... Mixing mechanism 51.52... Extrusion Forming mechanism 6... Biaxial stretching mechanism procedural amendment (voluntary) February 26, 1986 Michibe Uga, Commissioner of the Patent Office 1, Indication of the case Patent application No. 16721/1981 2, Name of the invention Colored heat Manufacturing method for plastic resin sheets 3, relationship with the amended case Patent applicant address 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Name (127) Konishiroku Photo Industry Co., Ltd. 4, Agent 5 , All drawings subject to correction 6, Contents of correction

Claims (1)

[Claims] 1) A step of mixing a thermoplastic resin chip and a fine dye powder, extruding the mixture, and then biaxially stretching the thermoplastic resin chip, wherein the average surface area of each thermoplastic resin chip is A.
Under the condition that the relationship between the surface area ΣA of the entire chip when A method for producing a colored thermoplastic resin sheet, comprising mixing the thermoplastic resin chips and the dye fine powder. Formula (1) ΣB≦3ΣA