JPS58101115A - Coloring method of polyimide - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a method for coloring polyimide.

More specifically, the present invention relates to a method for coloring polyimide, which comprises applying high-energy radiation or particle beams to polyimide composed of repeating units represented by a specific formula.

Various studies have been conducted on synthetic resins with color-forming properties, and in addition to creating color-forming synthetic resin compositions by adding color-forming additives, various synthetic resins that have color-forming properties on their own have been developed. or has already been discovered. These color-forming synthetic resins are used for recording elements such as images and signals,
It is used in many applications, such as copying sheets, recording materials such as microfilm, optical violet meters, and radiation dosimeters, or its use in these applications is being proposed or considered.

On the other hand, polyimide has attracted attention as a synthetic resin with excellent heat resistance, and much research has been conducted on its properties, manufacturing methods, uses, etc. However, the coloring properties of polyimide are not known.

As a result of extensive research into the color-forming properties of polyimide, the present inventors discovered that polyimide having a specific molecular structure exhibits reversible color-forming property, and thus arrived at the present invention.

That is, 1 the present invention is a repeating compound represented by the general formula (1): (wherein, R means a divalent hydrocarbon group in which at least one hydrogen atom is attached to each of the carbon atoms at both ends) This method consists of a method for coloring polyimide, which is characterized by applying high-energy radiation or particle beams to polyimide made up of units.

The polyimide having the above general formula (1) is an already known compound, or can be produced by a method similar to the production method of those known compounds. A typical manufacturing method is C, pyromellitic anhydride, and HN.
A method may be mentioned in which a diamine compound represented by -R-NH2 is subjected to condensation in a solvent such as N-methylpyrrolidone or dimethylformamide.

In the above general formula (1), R means a divalent hydrocarbon group in which at least one hydrogen atom is attached to each of the carbon atoms at both ends. It is preferable that the hydrocarbon chain forming the skeleton of this divalent hydrocarbon group is composed of a hydrocarbon group having 2 to 12 carbon atoms. Examples of such preferable divalent hydrocarbon groups include those having 2 to 1 carbon atoms;
Examples include a divalent aliphatic hydrocarbon group of 2, and a hydrocarbon group containing a saturated ring or an aromatic ring represented by the following chemical formula.

The divalent aliphatic hydrocarbon group having 2 to 12 carbon atoms has the general formula -(CH2). - A divalent hydrocarbon group represented by [where n means an integer of 2 to 12], specific examples of which include ethylene group, tetramethylene group, hexamethylene group, octamethylene group, etc. be able to.

Furthermore, the divalent hydrocarbon group represented by R is the above-mentioned H
It may contain any substituent such as a hydrocarbon group, as long as it does not violate the definition. Examples of divalent hydrocarbon groups containing such substituents include hydrocarbon groups represented by the following formulas.

CH3CH3 In the present invention, the polyimide represented by the general formula (1) can be used alone or in a composition with other synthetic resins and/or common synthetic resin additives, etc. to form powders, sheets, films, fibers, and molded materials. Coloring occurs when high-energy radiation or particle beams are applied to any form of material, such as objects or composites with other materials.

In this specification, radiation is a general term for electromagnetic radiation emitted from an object, such as light, X-rays, and gamma rays. In addition, in this specification, a particle beam refers to particles such as atoms, molecules, their ions, atomic nuclei, electrons, neutrons, etc.
It refers to a flow of charged particles flying in a fixed direction over a narrow width, and is a general term for alpha rays, beta rays, electron beams, etc.

Furthermore, the high-energy radiation or particle beam means, for example, ultraviolet rays with short wavelengths in the case of light beams. Specifically, when using light rays as an energy source for coloring, we use light rays centered on ultraviolet rays with wavelengths shorter than about 400n++. The use of electromagnetic radiation is undesirable.

These long-wavelength electromagnetic radiations are difficult to cause coloring of the polyimide of the present invention, and even if coloring occurs, the coloring ends instantly due to the heat energy imparted by the long-wavelength electromagnetic radiation, making it practical. It is unlikely to be colored in any meaningful sense. Therefore, in order to obtain a light beam suitable for implementing the coloring method of the present invention, a xenon lamp, a mercury lamp,
It is desirable to use a light source such as a tungsten lamp or a carbon arc, and sunlight can also be used by cutting off the infrared rays with a filter. For gamma rays, cobalt 60. Cesium 13? Electron beams obtained from accelerators such as Vandegraaf type, Kotscroft type, or transformer type are generally used.

The polyimide of the general formula (1) of the present invention is a colorless or pale yellow solid, but when exposed to high-energy radiation or particle beams as described above, the polyimide develops a greenish color. .

The retention time for this greenish coloring varies depending on the shape of the polyimide (particularly its thickness), the type of radiation or particle beam, the irradiation conditions, the environmental conditions after coloring, etc. By selecting , the coloring time of polyimide can be arbitrarily adjusted. For example, if polyimide is colored and then left in the air at room temperature,
The color gradually disappears, and eventually the polyimide returns to its colorless or pale yellow color. Furthermore, if the colored polyimide is left at room temperature, in a vacuum, or in a nitrogen atmosphere, this colored color will be maintained semi-permanently, for example, without fading for several years. On the other hand, by heating polyimide that has developed a single color, for example, in the absence of oxygen, the color can be erased within a short time. The time required for this decolorization varies depending on processing conditions such as heating temperature, but is usually within a range of several seconds to several minutes.

The coloration that appears in the polyimide of general formula (1) can disappear naturally or intentionally as described above. However, this polyimide after decoloring develops color again by being exposed to the above-mentioned high-energy radiation or particle beam again. Then, the general formula of the present invention (
Polyimide 1) is useful as a durable color-forming synthetic resin because it can undergo such coloring and decoloring processes repeatedly over a long period of time.

Next, production examples of polyimide of the present invention, examples of the present invention,
And a comparative example will be shown.

[Production Example 1 of Polyimide] After dissolving 061 mol of hexamethylene diamine in 100 mol of N-methylpyrrolidone, 0.1 mol of pyromellitic anhydride was added little by little under a nitrogen stream while stirring at room temperature. After maintaining the temperature at .degree. C. for 0.5 hour, heating was started. A powdery solid began to precipitate at about 110°C. The temperature was raised to 180°C over about 1.5 hours, and then the reaction solution was maintained at this temperature for 4 hours to perform a polycondensation reaction. After the reaction, the powdery solid was collected by filtration and a large amount of A white powder was obtained by washing with water and drying. As a result of subjecting this powder to infrared absorption spectrum measurement and elemental analysis, it was confirmed that it was a polyimide consisting of repeating units of the formula represented by the following formula.

[Production example 2 of polyimide] After dissolving 0.1 mol of m-xylylenediamine in 100 ml of N-methylpyrrolidone, 0.1 mol of pyromellitic anhydride was added little by little under a nitrogen stream while stirring at room temperature. Ta. When this solution was left to stand for about 4 hours, it became a viscous solution. This was cast onto a glass plate and placed under vacuum.
The mixture was heated at 00° C. for 1 hour to evaporate most of the N-methylpyrrolidone.

The temperature was further increased to 160°C under vacuum and the solution was held at this temperature for 24 hours. The product solidified on the glass plate was peeled off from the glass plate to obtain a colorless film.

This film was subjected to infrared absorption spectrum measurement and elemental analysis, and as a result, it was confirmed that it was a polyimide consisting of repeating units of the formula.

[Example 1] A 450 W high-pressure mercury lamp was applied to the powder of white polyimide (R is -(CH2)6- in general formula (1)) obtained in the above-mentioned [Polyimide Production Example 1]. When the powder was irradiated with ultraviolet light for 5 minutes, the powder turned green.

[Example 2] A film (thickness: 30p) of the polyimide (R in the general formula (1)) obtained in [Polyimide Production Example 2] was coated with 450W.
When irradiated with ultraviolet rays for 5 minutes using a high-pressure mercury lamp, the film developed a green color.

[Examples 3 to 12] When the polyimide films of Examples 3 to 12 were irradiated with ultraviolet rays under the same conditions as Example 2, each exhibited a greenish color. The results obtained are shown in Table 1. Note that the various films of Examples 3-12 were colorless or very pale yellow when not irradiated with ultraviolet rays.

Table 1 Examples　R color development of general formula (1) 3-CH2CH2-green 4　　　　　-(CH)　-Green.

10 5-(CH2)12- Pale green HCH 3 [Comparative Example 1-5] The same method as in Example 2 was carried out using a polyimide film in which R is a variety of groups not belonging to the present invention in the general formula (1). When irradiated with ultraviolet rays under these conditions, no change in color was observed. The results obtained are shown in Table 2.

Table 2 Comparative Examples R of General Formula (1) Before Irradiation After Irradiation [Example 1
3] A colorless polyimide film (thickness: 30jL) obtained by the same method as in the above-mentioned [Polyimide Production Example 2] and having the general formula (1) in which R is -(CH)-6 was placed in air. Then, use a cobalt 80 gamma ray irradiation device to
When the wire was irradiated with 1 megarad, a green color developed.

[Example 14] When a colorless film identical to the polyimide film used in Example 8 was irradiated with gamma rays in the same manner as in Example 13, it developed a green color.

Example 15] When a colorless film identical to the polyimide film used in Example 11 was irradiated with γ-rays in the same manner as in Example 13, it developed a green color.

[Example 16] A colorless film identical to the polyimide film used in Example 13 was placed in air and subjected to 1. When irradiated with an electron beam of 1 megarad, it developed a green color.

[Example 17] When a colorless film identical to the polyimide film used in Example 8 was irradiated with an electron beam on its side in the same manner as in Example 16, it developed a green color.

[Example 18] When a colorless film identical to the polyimide film used in Example 11 was irradiated with an electron beam on its side in the same manner as in Example 16, it developed a green color.

[Example 19] A colorless film identical to the polyimide film used in Example 13 was exposed to 50% ultraviolet light from a 450W high-pressure mercury lamp.
The film was irradiated for a minute to develop a green color. When this film was left in the air at room temperature, the color development duration was 20 hours. When the film, which had returned to colorless color, was irradiated with ultraviolet rays again under the same conditions, the film turned green again.

[Example 20] A colorless film identical to the polyimide film used in Example 13 was placed in a nitrogen atmosphere and irradiated with ultraviolet rays from a 450W high-pressure mercury lamp for 5 minutes, and the film developed a green color. When this green-colored film was stored at room temperature in a nitrogen atmosphere, the color did not change at all for over one year.

This color-developing film was left in a nitrogen atmosphere for 20 minutes.
When heated at 0° C. for several tens of seconds, the film returned to colorless. When this film, which had returned to colorless color, was irradiated with ultraviolet rays again under the same conditions, the film took on a green color again.

Patent applicant Ube Industries Co., Ltd. Agent: Patent attorney: Yasuo Yanagawa

Claims (1)

[Claims] 1° General formula (1): (wherein R means a divalent hydrocarbon group in which at least one hydrogen atom is attached to each of the carbon atoms at both ends) A method for coloring polyimide, which comprises applying high-energy radiation or particle beams to polyimide consisting of repeating units. 2゜The polyimide has the general formula (1), and R is a divalent hydrocarbon group having 2 to 12 carbon atoms with at least one hydrogen atom attached to each of the carbon atoms at both ends. A method for coloring polyimide according to claim 1, characterized in that: