JPH0692549B2 - Indicator ink for electron beam sterilization - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prints and displays a mark made up of characters, symbols and figures, or a combination thereof, which changes the color tone when irradiated with an electron beam to indicate the presence or absence of a history of electron beam irradiation. It is related to ink.

[0002]

2. Description of the Related Art Electron beam irradiation is used to sterilize medical equipment. The minimum irradiation dose required for sterilization is determined in consideration of the type of medical equipment, purpose of use, and the degree of bacterial contamination, but electron beam irradiation in other industrial fields (for example, chemical crosslinking of wire coating materials) Or a photoresist, etc.), which is a relatively low level, usually 1.5 to
A range of 2.5 megarads is used. That is, the minimum required irradiation dose for electron beam sterilization of medical equipment may be set to 1.5 megarads, and may be set to 2.5 megarads, and generally, it is set to a value in this range. On the other hand, in the practical aspect of sterilization operation by electron beam irradiation, an indicator for work management is used. In general, in this type of work, a label-shaped indicator for electron beam sterilization that changes color by electron beam irradiation is attached to an appropriate place such as the packaging material of the target device, and the color change situation accompanying the electron beam sterilization operation is visually checked. Then, one determines whether or not the electron beam irradiation is performed, and secondly, whether or not the electron beam irradiation amount is the minimum reference amount or more. The above label-like indicator that changes color by electron beam irradiation is printed with an indicator ink that changes color by receiving electron beam irradiation. Known indicator inks include those that consist of a pH indicator and a polymeric substance that releases hydrogen chloride upon irradiation with an electron beam. When the coating film printed with this indicator ink is irradiated with an electron beam, a part of the polymer substance is decomposed to release hydrogen chloride, and the released hydrogen chloride discolors the pH indicator. In an example of an indicator ink that constitutes an indicator for electron beam sterilization currently on the market, methyl yellow is used as a pH indicator and vinyl chloride resin is used as a hydrogen chloride releasing polymer substance. Then, a coating film having a thickness of 15 to 50 μm is formed on the substrate with this indicator ink. This coating film is yellow before electron beam irradiation, and turns red when it is irradiated with an electron beam of about 2.5 megarads.

[0003]

When the electron beam sterilization work of medical equipment is controlled by an indicator, The indicator does not discolor before it is exposed to the electron beam, b. It is the minimum irradiation dose for electron beam sterilization of medical equipment.
Discoloration of the indicator at 5 megarads, c. The discoloration due to the irradiation of 1.5 megarads described above progresses rapidly, d. It is necessary that the indicator discolored by electron beam irradiation does not fade over time, etc., but it does not cause discoloration called "fog", and even if the thickness of the coating film is small, it is against electron beam irradiation. It is desired to exhibit good discoloration. Next, the pre-irradiation discoloration and “fog” will be described. For example, when vinylidene chloride resin is used as a polymer substance that generates hydrogen chloride by electron beam irradiation, this vinylidene chloride resin has the property of easily generating hydrogen chloride by being decomposed not only by electron beams but also by ultraviolet rays. Therefore, there is a risk of discoloration due to diffused light in the room.
Furthermore, since this vinylidene chloride resin contains a small amount of hydrogen chloride without being decomposed, the pH indicator is easily discolored even without being irradiated with an electron beam. Therefore, when a vinylidene chloride resin and methyl yellow are printed with a mark or printed on a substrate with an indicator ink obtained by dissolving the solvent in a solvent, and dried, the methyl yellow does not change to red but becomes orange yellow, so-called `` "Fogging" occurs. In order to prevent such "fogging", ammonia or volatile amines are blended with the indicator ink to weaken the acidity,
Although a technique of extracting and removing hydrogen chloride as a pretreatment of the vinylidene chloride resin as a raw material is also known, it is not preferable because the solubility of the vinylidene chloride resin in a solvent is lowered and gelation occurs. The electron beam sterilization indicator on the sheet is formed by using an indicator ink, and painting or printing is used. In this case, for example, when the gravure printing technique is applied, the printed film becomes very thin, and the thin film is not easy to see the discoloration as compared with the thick film. Therefore, it is desired that the indicator ink exhibits good discoloration even when a thin film is formed. The present invention has been made in view of the above circumstances. The indicator does not discolor before being exposed to the electron beam.

B. A low level of about 1.5 megarads of electron beam irradiation causes sufficient discoloration, and c. The color tone after electron beam irradiation does not fade (good stability over time), d. It is an object of the present invention to provide an indicator ink for electron beam sterilization, which has a good discoloration property due to electron beam irradiation even when a thin film indicator is formed.

[0005]

[Means for Solving the Problems] The indicator ink according to the present invention has a structure for achieving the above object.
(A) a colored pigment that causes a change in color tone with a change in pH; (b) a polymeric substance containing 35% by weight or more of chlorine in the molecule; (c) a bisphenol compound; and (d) these agents. It is characterized by being composed of a soluble organic solvent. As the colored pigment that changes color with the above pH change,
It is desirable that the toner has a clear change in color tone in the range of 2.0 to 6.0. Further, in order to improve the stability of color tone over time after electron beam irradiation, it is a dye containing in its molecular structure an amino group or a lower alkyl group-substituted amino group that can chemically fix generated hydrogen chloride to some extent. Is desirable. That is, a dye represented by any one of the following general formulas (1) to (3) is recommended.

[0006]

[Chemical 4]

However, R ₁ represents a C _{1 to} C ₄ lower alkyl group, R ₂ represents a hydrogen atom or a C _{1 to} C ₄ lower alkyl group, and R ₃ independently of R ₂ represents a hydrogen atom. Or C
_It represents a lower alkyl group of _{1 to} C ₄ . The above general formula (1)
Among the dyes represented by, there are methyl yellow and ethyl yellow, which are widely used as pH indicators, and they are yellow when neutral and turn red when acidic. Although the dye represented by the general formula (2) has not been used as a pH indicator in the past, it is almost red when neutral and changes to purple or blue when it becomes acidic. Although the dye represented by the general formula (3) has not been known as a pH indicator in the past, it exhibits red when neutral and blue-purple when acidic. The polymer substance containing 35% or more of chlorine in the molecule serves as a hydrogen chloride generation source when irradiated with an electron beam, and also serves as a binder in the indicator ink. As the polymer substance of this kind, a vinyl chloride resin and a copolymer resin mainly composed of a vinyl chloride monomer and containing a small amount of a monomer such as vinyl acetate or vinylidene chloride are suitable. Since the above-mentioned copolymer resin is relatively stable to ultraviolet rays, discoloration is less likely to occur before electron beam irradiation. The above-mentioned bisphenol compound has a function of increasing the sensitivity of the color change reaction by electron beam irradiation. Suitable bisphenol resins for carrying out the present invention are shown in Tables 1 and 2.

[0008]

[Table 1]

[0009]

[Table 2]

[0010]

When the thin film made of the indicator ink having the above-mentioned structure is irradiated with an electron beam, a part of the polymer substance containing chlorine is decomposed and hydrogen chloride is released. As a result, the pH changes and the colored pigment changes its color to function as an indicator. Here, there is a large degree of freedom in selecting polymeric substances containing chlorine, but those that are easily discolored by electron irradiation have poor stability before electron irradiation, and those that have good stability before electron irradiation are discolored by electron irradiation. There is no perfect chlorine-containing polymer, such as the lack of sufficient properties. When a bisphenol compound is added as in the above constitution, the discoloration property upon irradiation is remarkably improved without impairing the stability before irradiation. The present inventor has found that drugs other than bisphenol (for example, malonic acid, 0-phthalic acid, naphthenic acid, salicylic acid, 2-oxy-3-naphthoic acid,
Diphenolic acid and other compounds containing a carboxyl group) were also tested, but the addition of these agents may cause so-called "fog", and if the amount is such that "fog" does not occur, the effect of improving discoloration does not occur. It was extremely weak. Bisphenol chemicals are less likely to cause "fog", improve discoloration due to electron beam irradiation, and improve stability over time before and after electron beam irradiation, but among many bisphenol compounds, there are advantages or disadvantages depending on the type. There is.
Among the No. 1 to No. 13 bisphenol compounds illustrated in Table 1, No. 10 bis (4-hydroxyphenyl) sulfide and No. 11 2.2 ′ thiobis (4-)
Chlorphenol) has relatively little improvement in storage stability and discolors when exposed to direct sunlight. However, it has practical value if it is encouraged to be stored away from direct sunlight. In Table 1, No. 1 2.2-bis (4-hydroxyphenyl) propane, No 4 1.1 bis (4-hydroxyphenyl) cyclohexane, No 9 bis (4-hydroxyphenyl) sulfone, and No 11 2. 2'-
Methylenebis (4-chlorophenol) has a remarkable effect of improving the temporal stability before and after electron beam irradiation. In addition to the composition of the indicator ink according to the present invention, a known substance that generates an acid or a free radical by electron beam irradiation (for example, triphenylsulfonium hexafluorophosphate, phenyltribromomethylsulfone, etc.) is blended. It is also possible to further improve the discoloration property during electron beam irradiation. In addition, it is possible to further improve the temporal stability (prevention of discoloration due to sunlight) before irradiation with an electron beam by incorporating an ultraviolet absorber.

[0011]

EXAMPLES Examples 1 to 11 and Comparative Examples 1 to 1
1 will be sequentially described. (Example 1) 1 part of methyl yellow as a colored pigment which causes a change in color tone with a change in pH, 35% by weight in a molecule
The above-mentioned high-molecular substance containing chlorine has an average degree of polymerization of about 50.
An indicator for electron beam sterilization by dissolving 100 parts of vinyl chloride resin of 0 and 25 parts of 2-2 bis (4-hydroxyphenyl) propane as a bisphenol compound in 500 parts of tetrahydrofuran as an organic solvent capable of dissolving them. I made an ink. The indicator ink prepared as described above is applied to the polyester film side of the base paper made by laminating a polyester film (thickness 12 μm) and paper (thickness 100 μm) with a Meyer bar (thickness 0.45 mm), After drying at 60 ° C, a yellow indicator for electron beam sterilization was obtained.

This indicator ink for electron beam sterilization contains
An electron beam with an accelerating voltage of 10 megaelectron volts is 1.5
Upon irradiation with megarad, the color tone of the indicator turned red. The indicator was exposed to direct sunlight for 2 hours before and after electron beam irradiation or kept at 40 ° C and 90% RH for 5 days, but no discoloration before irradiation or fading after irradiation was observed. It was Hereinafter, for convenience of explanation, the above-mentioned 10 mega electron volt, 1.5
Electron beam irradiation of Megarad is called electron beam irradiation test under standard conditions, exposure to direct sunlight for 2 hours is called light resistance test under standard conditions, and keeping at 40 ° C, 90% RH for 5 days is humidity resistance under standard conditions. It is called a sex test.

Comparative Example 1 An indicator ink for electron beam sterilization was carried out in the same manner as in Example 1 except that 2.2 bis (4-hydroxyphenyl) propane was omitted from the composition of the indicator ink of Example 1. Was prepared, coated on a base paper and dried in the same manner as in Example 1 to obtain a yellow indicator for electron beam sterilization. This electron beam sterilization indicator was subjected to an electron beam irradiation test, a light resistance test, and a moisture resistance test under standard conditions, and it was only discolored to yellow-orange due to the electron beam irradiation test, and the discoloration property was insufficient. It was judged to be none. In addition, the result of the moisture resistance test was slightly poor (slightly discolored).

(Comparative Example 2) The above-mentioned Example 1 and Comparative Example 1 were used as colored pigments which changed their color tone with the change of pH.
1 part of methyl yellow similar to the above, and 150 parts of vinylidene chloride resin as a polymer substance containing 35% by weight or more of chlorine in the molecule are used.
An indicator ink for electron beam sterilization was prepared by dissolving in 0 part. Using this indicator ink, an indicator for electron beam sterilization was obtained in the same manner as in Example 1. This indicator had a "fog" and had already been orange yellow before the electron beam irradiation. When subjected to an electron beam irradiation test and a light resistance test under standard conditions, the color changed from orange yellow to red, but there was little color difference, and the light resistance test also changed the color from orange yellow to orange red, so there was no practical use. To be judged.

Example 2 1 part of 4-methylthiazol-2-yl-azo-diethylamino-m-toluidine shown below was used as a colored dye whose color tone changed with the change of pH.

[0016]

[Chemical 5]

100 parts of a vinyl chloride-vinyl acetate copolymer having an average degree of polymerization of about 400 (about 10% by weight of vinyl acetate) as a polymeric substance containing 35% by weight or more of chlorine in the molecule,
In addition, 1.1 bis (4-
Hydroxyphenyl) cyclohexane (25 parts), methyl ethyl ketone (50) as an organic solvent capable of dissolving these
An indicator ink for electron beam sterilization was prepared by dissolving in 0 part. Using this indicator ink, a polyethylene-based high-density spunbond nonwoven fabric, which is a sterilization packaging material, was gravure-printed (plate depth 70 μm) and dried at 60 ° C. to obtain an almost red indicator for electron beam sterilization. When this electron indicator was subjected to an electron beam irradiation test under standard conditions, it turned purple. In addition, good results were obtained in the light resistance test and the humidity resistance test under the standard conditions.

Comparative Example 3 Electron beam sterilization was carried out in the same manner as in Example 2 except that 1.1 bis (4-hydroxyphenyl) cyclohexane as a bisphenol compound was removed from the composition of the indicator ink of Example 2. Indicator ink was prepared, gravure-printed in the same manner as in Example 2, and dried at 60 ° C. to obtain an almost red indicator for electron beam sterilization. When this indicator was subjected to an electron beam irradiation test under standard conditions, the color tone changed from red to brown, but the change in color tone was not clear, and it was judged to be impractical because it did not reach the light resistance and humidity resistance tests.

(Example 3) 1 part of a dye represented by the following structural formula as a colored dye which changes its color tone with a change in pH:

[0020]

[Chemical 6]

100 parts of a vinyl chloride-vinylidene chloride copolymer resin (about 10% by weight of vinylidene chloride) having an average degree of polymerization of about 400 as a polymeric substance containing 35% by weight or more of chlorine in the molecule, and a bisphenol compound ,
25 parts of bis (4-hydroxyphenyl) sulfone was dissolved in 1000 parts of a mixed solvent (1: 2 mixed solution of tetrahydrofuran and methyl ethyl ketone) to prepare an indicator ink for electron beam sterilization. Using this indicator ink, a base paper was coated and dried in the same manner as in Example 1 to obtain a red indicator for electron beam sterilization. When this electron beam sterilization indicator was subjected to an electron beam irradiation test under standard conditions, it turned a bluish purple color. Also, good light resistance and light resistance test under standard conditions
Moisture resistance was confirmed.

Comparative Example 4 From the composition of the indicator ink of Example 3, bis (4-) as a bisphenol compound was used.
An indicator ink was prepared in the same manner as in Example 3 except that hydroxyphenyl) sulfone was removed, and applied to a base paper and dried in the same manner as in Example 3 to obtain an almost red indicator for electron beam sterilization. When an electron beam irradiation test was performed on this indicator under standard conditions, the color change was not clear because the color changed from red to dark brown only, and it was judged to have no practicality because it did not reach the light resistance test and the humidity resistance test.

(Embodiment 4) As in Embodiment 2, as a colored pigment which causes a change in color tone with a change in pH,
-Methylthiazol-2-yl-azo-diethylamino-m-toluidine 1 part, Kayasset Yellow 476 (manufactured by Nippon Kayaku Co., Ltd.), which is a yellow pigment that does not discolor with a change in pH, 1.5 parts, molecule 100 parts of vinyl chloride resin (average polymerization degree of about 500), which is a polymeric substance containing 35% by weight or more of chlorine, and 2.2'-methylenebis (4-chlorophenol), which is a bisphenol compound
20 parts was dissolved in 500 parts of tetrahydrofuran, which is an organic solvent capable of dissolving them, to prepare an indicator ink for electron beam sterilization. This indicator ink was applied to a base paper and dried in the same manner as in Example 1 to obtain an electron beam sterilization indicator having a slightly dark red color tone. When an electron beam irradiation test was conducted on this indicator under standard conditions, it changed to dark green. Also,
Good results were also confirmed for the light resistance test and the humidity resistance test under the standard conditions.

(Examples 5 to 11 and Comparative Examples 5 to 11) In these Examples and Comparative Examples, each of various compounds belonging to the bisphenol compound is a bisphenol compound which is an essential constituent requirement of the indicator ink according to the present invention. Can the effects of the present invention be exerted,
Further, it is an experiment conducted to confirm whether or not the effects of the present invention cannot be achieved with various organic acids other than the bisphenol compound.

In advance, methyl yellow and a vinyl chloride-vinylidene chloride copolymer resin were dissolved in a mixed solvent. 14 solutions having the same composition were pumped out. The details are as follows. 1 part of methyl yellow as a colored pigment that changes its color tone with a change in pH, and vinyl chloride-vinylidene chloride copolymer resin (average polymerization as a polymer substance containing 35% by weight or more of chlorine in the molecule) Degree 400, vinylidene chloride about 10%) 100 parts and dissolve in 500 parts of a mixed solvent of tetrahydrofuran and methyl ethyl ketone (1: 2) to dissolve 7 parts for Examples 5-11 and Comparative Examples 5-11. It was divided into 14 pieces in total with 7 pieces. As shown in Table 2, 7 kinds of these 14 bisphenol compounds were mixed and dissolved to prepare the electron beam sterilization indicator inks of Examples 5 to 11, and the remaining 7 bisphenol compounds were prepared. Various organic acids were mixed and dissolved in each of the six of them to prepare electron beam sterilization indicator inks of Comparative Examples 6 to 11. The blending amount of the bisphenol compound and other organic acids in these Examples and Comparative Examples was set to the maximum amount within the range where significant "fog" was not generated. Comparative Example 5
Does not contain organic acid.

The indicator ink for electron beam sterilization of each of these Examples and Comparative Examples was subjected to gravure printing in the same manner as in Example 2 and Comparative Example 3 to prepare an indicator for electron beam sterilization. The electron beam sterilization indicators of Examples 5 to 11 and Comparative Examples 5 to 11 all had a substantially yellow color. Table 2 shows the discolored states as a result of the electron beam irradiation test conducted on these under standard conditions.

[0027]

[Table 3]

In each of Examples 5, 6 and 8 to 11, the color changed from yellow to red, and the color tone change was clear.
In Example 7, the color changed from yellow to orange-red, and the clearness of the color tone change was almost good. Comparative Example 5 (containing no organic acid) was slightly yellowish to yellowish in color, and its color tone change was unclear. Each of Comparative Examples 6 to 11 changed from yellow to yellow-orange, but comparing these with Comparative Example 5, the effect of improving discoloration by adding an organic acid other than the bisphenol compound was weak. It was

Table 3 shows the results of the light resistance test and the moisture resistance test conducted on the above-mentioned Examples 5 to 11 and Comparative Example 5 (without organic acid) under standard conditions.

[0030]

[Table 4]

[0031]

As described above, the indicator ink for electron beam sterilization formed by applying the present invention clearly discolors by electron beam irradiation of about 1.5 megarads even when a thin film indicator is formed. Moreover, discoloration is difficult to progress even if exposed to direct sunlight before electron beam irradiation, and it is excellent in light resistance, and it does not easily fade even if left in high temperature and high humidity after discolored by electron beam irradiation. Has excellent moisture resistance.
In particular, since it is possible to reliably detect a relatively low level of irradiation dose such as about 1.5 megarad, it is of great practical value in the sterilization work management of medical equipment that is sterilized near this level.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hideyuki Toyota, 298 Ushiku Medical Research and Development Department, Ushiku, Ushiku, Ibaraki Prefecture (72) Yuji Kumata 298 Ushiku, Ushiku, Ibaraki, Hogi Medical Research & Development Co., Ltd. Department

Claims (5)

[Claims] 1. A colored pigment that causes a change in color tone with a change in pH, (b) a polymeric substance containing 35% by weight or more of chlorine in a molecule, (c) a bisphenol compound, and (d). An indicator ink for electron beam sterilization comprising an organic solvent capable of dissolving each of the above substances. 2. The indicator ink for electron beam sterilization according to claim 1, wherein the colored dye is a dye represented by the following general formula (1). [Chemical 1] However, the above R ₁ represents a C ₁ -C ₄ lower alkyl group. 3. The indicator ink for electron beam sterilization according to claim 1, wherein the colored dye is a dye represented by the following general formula (2). [Chemical 2] However, R ₂ represents a hydrogen atom or a C ₁ -C ₄ lower alkyl group, and R ₃ represents a hydrogen atom or a C ₁ -C ₄ lower alkyl group independently of R ₂ . 4. The colored dye is a dye represented by the following general formula (3). The indicator ink for electron beam sterilization according to claim 1. [Chemical 3] 5. The bisphenol compound is characterized in that it has no substituent in at least one of the ortho positions with respect to the phenolic hydroxyl group and does not contain a carboxyl group in the molecule. The indicator ink for electron beam sterilization according to any one of claims 1 to 4.