JPS622305B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a colored polyester film, and more particularly to a blue or blue-purple colored polyester film for use in X-ray photography.

Conventionally, the support film of an X-ray photographic film is colored blue or blue-purple in order to facilitate the identification of the photographic image. In addition, the colorant used must have heat resistance to withstand high-temperature processing conditions during molding, and for this purpose,
Special blue coloring agents are exemplified in Japanese Patent Publications No. 47-8734, Japanese Patent Publication No. 30294-1983, Japanese Patent Application Laid-open No. 36278-1987, and the like. In particular, the Special Public Interest Publication No. 47-30294
The two-component coloring agent of Color Index Solvent Blue 45 Terrasol Blue RLS and a phthalocyanine-based blue pigment shown in the publication is excellent in terms of vivid blue color and heat resistance. be.

Conventional methods for incorporating a coloring agent into polyester include adding it during synthesis of polyester, or adding and mixing it during hot melt molding and uniformly dispersing it in polyester.
Among these, the method of adding a colorant during polyester synthesis is superior in terms of uniform dispersion. Polyester film is usually produced using a tenter method, and the edge loss that occurs during this process is collected and reused.
Therefore, when a coloring agent with poor thermal stability is recovered and used, the color tone changes and the product value is significantly reduced. Color Index Solvent Blue 45 and phthalocyanine blue pigments are excellent from this point of view, but in recent years there has been a particular demand for color uniformity in colored films for X-rays, and conventionally colored polyesters In the method of obtaining a colored film from raw materials, it was inevitable that slight differences in color tone would occur depending on the mixing ratio of the recovered and used selvedges.

The present inventors have arrived at the present invention as a result of intensive studies to obtain a colored polyester film that always has a uniform color tone.

That is, the present invention provides substantially colorant-free polyester pellets, Color Index Solvent Blue 45.
Polyester pellets containing a high concentration of
Polyester pellets containing a high concentration of phthalocyanine blue pigment with maximum absorption near 676 mμ,
A film is formed by mixing the colored polyester that was collected as the ear part during the production of the colored film and JIS
In the chromaticity diagram specified in Z8701-1958, point 1
(x=0.284, y=0.305) and point 2 (x=0.276, y
=0.302), point 3 (x=0.280, y=
0.294) and point 4 (x = 0.287, y = 0.299), a line and point connecting points 1 and 4 with an arc centered on the chromaticity point of the standard illuminant at (x = 0.3101, y = 0.3163) This method of producing a colored polyester film is characterized in that the film is colored to have a chromaticity within the range surrounded by the line connecting points 2 and 3.

The polyester referred to in the present invention mainly refers to polyethylene terephthalate, but a portion (usually 40 mol% or less) of the terephthalic acid component is used to add other difunctional carboxylic acid components, such as β-hydroxyethoxybenzoic acid, p- Replaced with hydroxybenzoic acid, isophthalic acid, diphenylsulfone dicarboxylic acid, diphenylmethane dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, naphthalene dicarboxylic acid, adipic acid, sebacic acid, etc. and/or a part (usually 40 mol% or less) of the ethylene glycol component can be added to other diol components, such as trimethylene glycol, tetramethylene glycol, hexamethylene glycol, propylene glycol, 1,4-cyclohexanediol,
1,4-cyclohexanedimethanol, 1,4-
Bishydroxyethoxybenzene, bisphenol A, etc. may be substituted.

Furthermore, even if the polyester is copolymerized with a monofunctional compound such as benzoylbenzoic acid or benzyloxybenzoic acid at its terminal end, trifunctional or higher polyfunctional compounds may be copolymerized to the extent that the thermoplasticity is not substantially impaired. A compound such as glycerin, pentaerythritol, trimesic acid, etc. may be copolymerized.

The polyester is manufactured by any method. To explain polyethylene terephthalate, it is usually produced by directly esterifying terephthalic acid and ethylene glycol, by transesterifying dimethyl terephthalate and ethylene glycol, or by reacting terephthalic acid and ethylene oxide. A method is employed in which a glycol ester of terephthalic acid and/or a low polymer thereof is produced, and then this product is polycondensed to a predetermined degree of polymerization. At this time, a catalyst can be used if necessary, but it is preferable to select its type and amount so that the color tone of the resulting polymer does not deteriorate too much. Moreover, arbitrary additives may be included as necessary.

In the present invention, a chip containing substantially no colorant added to the polyester, a chip containing Color Index Solvent Blue 45, and a chip containing a visible absorption spectrum in the polyester are used.
Three types of chips are used, one containing a phthalocyanine blue dye with maximum absorption near 609 mμ and another around 676 mμ, and colored polyester recovered as the edge part during the production of the colored film is used. The recovered colored polyester may be in the form of pellets or flakes, but pellets are preferred.

Examples of Color Index Solvent Blue 45 used as a coloring agent include Acetosol Blue RLS, Savinyl Blue RS, and Terrasol Blue RLS manufactured by Sandoz. (Telasol Blue RLS) is known, and as a phthalocyanine blue dye whose visible absorption spectrum in polyester has maximum absorption around 609 mμ and around 676 mμ, for example, Nylofil Blue BLL manufactured by Sandotsu Co., Ltd.
(Nylofil Blue BLL), Graftol Blue BL
(Graphtol Blue BL), Graftol Blue
2GLS, Ciba product name Gromophtal Blue 4G, Bayer product name Plastic Blue B
(Plastic Blue B), Dainichiseika Chemical Co., Ltd. product names Cyanine Blue BX, Cyanine Blue BF, Cyanine Blue S-10, Cyanine Blue NSG, etc.

The Color Index Solvent Blue 45 or phthalocyanine blue pigment can be added to the polyester at any time when it can be uniformly dissolved and dispersed, such as during polyester synthesis or sprinkled on pellets before molding. However, it is simple and preferable to add it during the synthesis, particularly at the initiation stage of polycondensation to drive out ethylene glycol. As for the addition method, it can be added by any method that can obtain uniform dissolution and dispersion in the polyester. For example, when adding it during polyester synthesis,
It is preferable to form an ethylene glycol slurry in advance and then add it. The concentration of Color Index Solvent Blue 45 or the phthalocyanine blue pigment added should be higher than the concentration of these colorants in the intended film, and is usually several times the concentration.

The feature of the present invention is to use a mixture of the above-mentioned four types of polyesters to obtain a film with a uniform color tone.The color matching of the film will be described in detail below. The principle of color matching is basically the same as the color matching when three types of pellets are mixed, so the explanation will be given below using three types of pellets.

Figure 1 shows the chromaticity diagram specified in JIS Z8701-1958. Point C is the chromaticity point of standard illuminant C. In the figure, points A and B are the chromaticity points of films with different color tones, and when made into a film, polyesters having the chromaticity of points A and B are mixed in an arbitrary ratio to form a film. is obtained on the straight line connecting points A and B, and any chromaticity D on the line segments A and B can be obtained depending on the ratio of the components of A and B. Point P is the chromaticity point of the film with the desired color, but it can be obtained by mixing polyester containing no colorant with polyester having color D obtained from the two components A and B. be able to. That is, the chromaticity D obtained by mixing A and B
By diluting the concentration of the colorant contained in the polyester with a polyester that does not contain a colorant, it is possible to move on a straight line connecting points D and C, and as a result, the desired chromaticity P can be obtained. can.

By combining the necessity of the color tone of the mixture of two types of colored chips in this method with the direction of change in color tone obtained by changing the density, it is possible to design any color tone on a desk. In the invention, polyester chips containing the above Color Index Solvent Blue 45 at a high concentration, polyester chips containing the above phthalocyanine blue pigment at a high concentration, and polyester chips containing substantially no colorant are recovered. The colored polyester is mixed with the colored polyester, and a film is formed to have a chromaticity in the range surrounded by points 1, 2, 3, and 4 shown in FIG. Outside this range, it is unsuitable for use in X-ray photography. In addition, Figure 2 is based on the JIS standard as well as Figure 1.
This is a chromaticity diagram defined in Z8701-1958, where point 1 is x=0.284, y=0.305, and point 2 is x=0.276, y=
0.302, point 3 is x=0.280, y=0.294, point 4 is x=
0.287, y=0.299, and the center point of the arc connecting points 1 and 4 and the arc connecting points 2 and 3 is x=
This is the chromaticity point of the standard light source with 0.3101 and y=0.3163.

Note that the same applies to the case of mixing not only two types of colored chips but also three or more types of colored chips, but a mixture of two types is usually sufficient. Furthermore, this method is not limited to blue, but can also be applied to red, yellow, and other colors.

By using the above-mentioned method, although the usage ratio of the colored polyester recovered as the edge during the film production is changed, the raw material colored master polyester pellets and the polyester pellets containing no colorant are changed according to this ratio. By changing the ratio, it is possible to always obtain a film with the same color tone.

Another advantage of the present invention is that it provides films of the same raw material, of different thicknesses, but of exactly the same color tone. That is, by changing the dilution ratio with colorless polyester pellets, it is possible to easily obtain a film with exactly the same color tone even if the thickness changes.

When pellets of different colors are mixed and melt-extruded to form a film, sufficient kneading can be carried out using a commonly used static mixer, and a commonly used film forming method can be used.

Next, examples will be shown. In the examples, parts represent parts by weight, and the chromaticity coordinates were calculated according to the method specified in JIS8701-1958.

Example 1 Pellets containing 0.1 part of Terrasol Blue RLS to 99.9 parts of polyethylene terephthalate, pellets containing 0.1 part of Graftol Blue 2GLS to 99.9 parts of polyethylene terephthalate, and polyethylene terephthalate pellets containing no colorant. They were mixed at a weight ratio of 0.315:0.035:0.65, and kneaded and extruded using an extruder to obtain an unstretched sheet. Then, under heating conditions of 90℃, machine direction
The film was stretched 3.5 times, and further stretched 3.7 times in the right angle direction under heating conditions of 110° C. to obtain a biaxially stretched film with a thickness of 175 μm.

The chromaticity point of this film is x=0.2845, y=
0.3020, and the film was excellent as an X-ray photographic film, free from defects such as decreased transparency, cloudiness, and undispersed particles.

The film obtained above was crushed, remelted at 290°C, and pelletized again. This pellet and each pellet of Example 1 above were mixed at 0.30:0.233:
They were mixed at a weight ratio of 0.026:0.441, and a biaxially stretched film was obtained in the same manner as above. The chromaticity points of this film were x = 0.2842 and y = 0.3018, and when visually observed, the film had a color tone that was completely the same as the above film.

Comparative Example 1 A pellet containing 0.0315 part of Telazol Blue RLS and 0.0035 part of Graftol Blue based on 99.965 parts of polyethylene terephthalate was made into a film in the same manner as in Example 1, further crushed and remelted, and pelletized again. The first pellets and the re-produced pellets were mixed at a ratio of 0.70:0.30 and film-formed again to obtain a biaxially stretched film.

The chromaticity points of these two types of films are: x = 0.2845, y = 0.3023 for the first film, and x = 0.2860, y = 0.3030 for the film formed by mixing remelted pellets.
The former was an excellent film with a bright blue color, but the latter had a yellowish tinge and was unsatisfactory as an X-ray photographic film as the photographic image was unclear.

Example 2 Polyethylene terephthalate pellets containing Terrasol Blue RLS of Example 1, 99.9 parts of polyethylene terephthalate, pellets containing 0.1 part of Chromophthal Blue 4G and 0.357 parts of polyethylene terephthalate containing no colorant:
They were mixed at a weight ratio of 0.023:0.620, and a biaxially stretched film with a thickness of 175 μm was obtained after melting and film forming. Next, add the above polyethylene terephthalate to 0.625:0.040:
Mix at a weight ratio of 0.335 and prepare in the same way to a thickness of 100 μm.
A biaxially stretched film was obtained.

The chromaticity points of the two types of films were: x=0.2837, y=0.2980 for the 175 μm film, and x=0.2840, y=0.2983 for the 100 μm film. Both films differed only in thickness, and their color tone was visually the same.

[Brief explanation of the drawing]

FIG. 1 is a chromaticity diagram defined in JIS Z8701-1958, and FIG. 2 is a similar chromaticity diagram specifically showing the scope of claims of the present invention. 2 shows the chromaticity point of the film of Example 1,' indicates the chromaticity point of Comparative Example 1, and indicates the chromaticity point of Example 2, respectively.

Claims (1)

[Claims] 1 Polyester pellets containing virtually no colorant, polyester pellets containing a high concentration of Color Index Solvent Blue 45, visible absorption spectra in polyester around 609 mμ and around 676 mμ Polyester pellets containing a high concentration of phthalocyanine-based blue pigment with maximum absorption are mixed with the colored polyester that was recovered as the edges during the production of the colored film to form a film to achieve the chromaticity specified in JIS Z8701/1958. In the figure, point 1 (x=0.284,
Straight line connecting point 2 (x=0.276, y=0.302), point 3 (x=0.280, y=0.294) and point 4
A straight line connecting (x=0.287, y=0.299), (x=
0.3101, y=0.3163) A line connecting points 1 and 4 with an arc centered on the chromaticity point of the standard illuminant, and points 2 and 3
1. A method for producing a colored polyester film, characterized in that the film is colored with a chromaticity within a range surrounded by a line connecting .