JP6736433B2 - Radiation resistant vinyl chloride resin composition and flexible hose and tube containing the radiation resistant vinyl chloride resin composition - Google Patents

Description

The present invention relates to a radiation resistant vinyl chloride resin composition in which deterioration due to radiation irradiation is suppressed. In particular, it relates to a soft radiation resistant vinyl chloride resin composition containing a plasticizer. The present invention also relates to a flexible hose containing such a radiation resistant vinyl chloride resin composition in the hose wall. The present invention also relates to a flexible tube formed of such a radiation resistant vinyl chloride resin composition.

Vinyl chloride resin has high versatility and is used for various purposes. In particular, the vinyl chloride resin composition containing a plasticizer is soft and highly flexible and can be used for various hoses, for example, hoses for electric vacuum cleaners and hoses for various industries.

Various resin compositions may be used in an environment exposed to radiation. For example, when vinyl chloride resin is used for medical equipment, it is exposed to radiation during sterilization work by radiation. Moreover, when a hose or the like made of vinyl chloride resin is used for piping in a medical radiation facility or the like, it is exposed to radiation. Generally, when a vinyl chloride resin is exposed to radiation, physical properties such as strength and elongation of the resin are deteriorated, and the life of a product in which the vinyl chloride resin is used is shortened. Therefore, deterioration of the vinyl chloride resin composition due to radiation is suppressed. Is required.

Patent Document 1 discloses a radiation resistant polyvinyl chloride resin composition containing di(ethylhexyl) phthalate. The vinyl chloride resin composition is suitable for applications such as medical instruments because it has less deterioration of physical properties and discoloration.
Patent Document 2 discloses a medical radiation sterilization-compatible vinyl chloride resin composition containing an epoxyhexahydrophthalic acid ester plasticizer. This vinyl chloride resin composition has excellent resistance to discoloration against radiation sterilization.

Japanese Patent Laid-Open No. 05-051630 JP, 2005-030773, A

In recent years, there has been a growing need to use flexible hoses and tubes in nuclear power plants, nuclear reactors, fuel reprocessing plants, disposal facilities and related facilities. On the other hand, in such facilities, the air dose of radiation may be high or the integrated dose may be high, so soft resins such as those used for general flexible hoses and flexible tubes are It has been considered unsuitable for use because it is deteriorated by radiation.

In such nuclear facilities, it is necessary to assume a level of 1 MGy (mega gray) to 5 MGy as the total absorbed dose. However, in the conventional soft vinyl chloride resin, for example, as shown in “JAERI-DATA/CODE 2003-015 radiation resistance characteristics of polymer materials and data collection page 49, data sheet No PVC-2”, Only by receiving gamma (γ) ray irradiation of about 1 MGy, the tensile elongation of the resin is significantly lower than 100%, and the characteristic deterioration as a soft resin is remarkable. Therefore, it is difficult to use such a vinyl chloride resin for a flexible hose or a flexible tube used in an environment exposed to such a high level of radiation.

Further, the radiation-resistant vinyl chloride resin composition as disclosed in Patent Document 1 or Patent Document 2 is mainly used as a resin composition in the case of irradiation with sterilizing radiation for medical use, where the irradiation dose is very limited. It is a technology that only suppresses discoloration. Therefore, even the radiation-resistant vinyl chloride resin compositions of these patent documents have not been considered to bring about a reduction in physical properties such as strength and elongation with respect to radiation exposure of an absorbed dose of the order of 1 MGy.

That is, although the soft vinyl chloride resin is rich in versatility such as flexibility and moldability, it does not show strength and elongation in an environment exposed to a high level of total absorbed dose of radiation of the order of 1 to several megagrays. The physical properties are remarkably deteriorated, and it has not been considered to be usable for applications such as flexible hoses and flexible tubes in nuclear facilities. Further, little research has been conducted on means for suppressing the deterioration of the physical properties of the vinyl chloride resin composition in such a high level absorbed dose region.

An object of the present invention is to suppress radiation deterioration of a soft vinyl chloride resin composition when the absorbed dose of γ rays is on the order of mega gray. Another object of the present invention is to provide a flexible hose or flexible tube in which deterioration due to radiation is suppressed.

As a result of earnest studies, the inventor has found that the radiation resistance of the soft vinyl chloride resin composition can be improved by adding a phenyl ether-based oil and fat in addition to the plasticizer, and completed the present invention.

The present invention contains 100 parts by weight of a vinyl chloride resin , 20 parts by weight or more and 110 parts by weight or less of a benzoic acid plasticizer, and 1 part by weight or more and 15 parts by weight or less of a phenyl ether oil or fat, and before γ-irradiation. Is a radiation resistant vinyl chloride resin composition having a Duro A hardness of 50 HDA or more and 95 HDA or less and an elongation of 100% or more when the absorption amount of γ rays reaches 3 MGy (first invention).

In the first invention, preferably, the radiation resistant vinyl chloride resin composition contains 10 parts by weight or more and 50 parts by weight or less of carbon black or graphite powder ( second invention).

The present invention is also a flexible hose including the radiation resistant vinyl chloride resin composition of the first invention or the second invention in a hose wall ( third invention). Further, the present invention is a flexible tube formed from the radiation resistant vinyl chloride resin composition of the first invention or the second invention ( fourth invention).

The radiation-resistant vinyl chloride resin composition (first invention) of the present invention suppresses deterioration of the strength and elongation of the resin even when the absorbed dose of gamma rays is a high level of radiation dose of the order of megagray. In the second invention , the effect of suppressing deterioration is further enhanced. Further, the flexible hose of the third aspect of the invention and the flexible tube of the fourth aspect of the invention are flexible hoses and flexible tubes in which the radiation resistance of the hose walls and tubes is increased.

It is a partial cross section figure which shows the structure of the flexible hose regarding this invention.

Hereinafter, embodiments of the invention will be described with reference to the drawings as necessary. The invention is not limited to the individual embodiments described below, and the embodiments can be modified and implemented.

The radiation resistant vinyl chloride resin composition of the first embodiment contains 100 parts by weight of a vinyl chloride resin, a plasticizer, and 1 part by weight or more and 15 parts by weight or less of a phenyl ether oil or fat.

The vinyl chloride resin is not particularly limited, but preferably has an average degree of polymerization of 1000 or more and 5000 or less, and particularly preferably 2000 or more and 3000 or less. Various functional groups may be introduced into the vinyl chloride resin. Further, the vinyl chloride resin is not limited to a polymer of vinyl chloride monomer alone, and may be a copolymer or graft polymer of vinyl chloride monomer and other monomer components. Further, a copolymer of vinyl chloride monomer and other monomer components or a graft polymer and a polymer of vinyl chloride monomer alone may be blended to obtain the vinyl chloride resin in the present embodiment.
As a graft polymer of a vinyl chloride monomer and other monomer components, for example, EVA (ethylene-vinyl acetate copolymer) is used as a trunk, and a graft copolymer obtained by graft-polymerizing vinyl chloride onto it (Sekisui Chemical Co., Ltd. From the PVC-TG series), a resin obtained by completely graft-copolymerizing an acrylic resin with a vinyl chloride resin (a resin sold from Kaneka Corporation as the Plectomer series), and the like.

A plasticizer is added so that the radiation resistant vinyl chloride resin composition becomes a so-called soft vinyl chloride resin. The blending amount of the plasticizer may be adjusted so as to obtain a predetermined hardness described later. The blending amount of the plasticizer is typically 20 parts by weight or more and 200 parts by weight or less, more preferably 30 parts by weight or more and 150 parts by weight or less with respect to 100 parts by weight of the vinyl chloride resin. Adjusted.

As the plasticizer, known plasticizers such as phthalate ester plasticizers (DOP etc.) can be used. As the plasticizer, it is preferable to add a benzoic acid plasticizer (particularly a benzoic acid ester plasticizer), and in this case, 20 parts by weight or more and 110 parts by weight or more of the benzoic acid plasticizer with respect to 100 parts by weight of the vinyl chloride resin. It is more preferable to add the following components, and it is particularly preferable to add the components in an amount of 30 parts by weight or more and 100 parts by weight or less. Examples of the benzoic acid ester contained in the benzoic acid plasticizer include diethylene glycol dibenzoate, dipropylene glycol dibenzoate, and 1-4-cyclohexene dimethanol dibenzoate. Examples of the benzoic acid-based plasticizer include plasticizer of model number PB-3A and plasticizer of model number PB-3 sold by DIC Corporation under the product name of Monosizer, and plasticizer of model number JP120 of J-Plus Co., Ltd. Examples thereof include agents and plasticizers of model number 9-88 sold under the product name BENZOFLEX of Eastman Chemical Company.

As the phenyl ether oil and fat, oils and fats such as diphenyl ether and polyphenyl ether can be used. Among the diphenyl ethers, alkyl diphenyl ether oils and fats can be preferably used. A functional group other than an alkyl group may be introduced into the phenyl ether oil and fat. Examples of the alkyl diphenyl ether-based fats and oils include the fats and oils of model number RA-100 and the fats and oils of model number RA-15, which are sold as lubricating oils and greases under the trade name of Hyrad by MORESCO Co., Ltd., for example. Examples of the polyphenyl ether-based fats and oils include model RP-42R fats and oils sold by MORESCO, Inc. under the trade name of Hirad. As described above, 1 part by weight or more and 15 parts by weight or less of these phenyl ether-based oils and fats are mixed with 100 parts by weight of the vinyl chloride resin.

The radiation resistant vinyl chloride resin composition has a degree of flexibility suitable for use in, for example, a hose wall of a flexible hose, and the degree of flexibility is determined according to JIS K7215 before γ-ray irradiation. The hardness is 50 HDA or more and 95 HDA or less in terms of Duro A hardness. If the hardness is in this range, it is in the category of so-called soft vinyl chloride resin, and it is easy to apply it to a flexible hose with an existing design.

The radiation resistant vinyl chloride resin composition may preferably contain fine carbon powder, that is, carbon black or graphite powder. The type of carbon black is not particularly limited, and carbon such as furnace black, channel black, acetylene black, and thermal black can be used, and from these, those having good dispersibility in vinyl chloride resin are selected and used. be able to. The type of graphite powder is also not particularly limited, and artificial graphite powder and powdered expanded graphite can be used. Both carbon black and graphite powder may be contained. The blending amount of the carbon black or graphite powder is preferably 10 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the vinyl chloride resin.

Other components may be added to the radiation resistant vinyl chloride resin composition for various purposes such as improving the dispersibility of the compounding components, enhancing the handling properties, or enhancing the specific properties. For example, known stabilizers or heat stabilizers may be added in order to enhance the stability of the material, particularly the heat stability. Similarly, anti-aging agents, processing aids, lubricants, pigments and the like may be added.

The radiation resistant vinyl chloride resin composition can be obtained by a known method for producing a vinyl chloride resin composition. That is, the intended vinyl chloride resin composition can be obtained by uniformly adding the components to be mixed to the base vinyl chloride resin while uniformly dispersing the components by a kneading roll or the like. Depending on the difficulty of kneading the components, a masterbatch or the like may be used if necessary.

FIG. 1 shows a flexible hose 1 having a hose wall 2 made of the radiation resistant vinyl chloride resin composition of the first embodiment. In FIG. 1, the upper half is shown in cross section and the lower half is shown in appearance. In this embodiment, the hose wall 2 is formed in a spiral bellows shape. Further, the flexible hose 1 is constructed by embedding a spiral reinforcing body 3 made of hard steel wire in the hose wall 2. This hose has appropriate flexibility and can be used for various pipes. Note that the material of the reinforcing body 3 may be another material, and the form in which the reinforcing body 3 is integrated with the hose wall 2 is not only the embedding form, but also the form in which the reinforcing body 3 is integrally bonded to the inner circumference or the outer circumference of the hose wall. May be Such a flexible hose 1 can be manufactured by a known hose manufacturing method.

A flexible tube can also be formed from the radiation resistant vinyl chloride resin composition of the first embodiment. The flexible tube typically has a cylindrical tube wall, and the tube wall is formed of the radiation resistant vinyl chloride resin composition. Such flexible tubes are typically manufactured by extrusion. Such a flexible tube has appropriate flexibility and can be used for various pipes and the like.
Further, the radiation resistant vinyl chloride resin composition can also be applied to other uses in which a soft vinyl chloride resin is used, such as coating of electric wires. In addition, the radiation resistant vinyl chloride resin composition is blended with a shielding material such as barium sulfate, tungsten, or lead to obtain a resin composition having radiation shielding performance, which is molded into a soft sheet or a soft cover for use. You can also

The action and effect of the radiation resistant vinyl chloride resin composition of the above embodiment will be described. The radiation resistant vinyl chloride resin composition contains 100 parts by weight of a vinyl chloride resin, a plasticizer, and 1 part by weight or more and 15 parts by weight or less of a phenyl ether oil and fat, so that the absorbed dose is high on the order of megagray. Even when exposed to a level of radiation (γ-ray), deterioration of the strength and elongation of the resin is suppressed.

Further, among the radiation-resistant vinyl chloride resin compositions of the above-described embodiments, those having higher radiation-resistant properties can maintain the elongation at about 100% even when the absorbed dose of γ-ray reaches 3 MGy. Such properties are particularly suitable for use in flexible hoses used in environments exposed to high levels of radiation.

The following mechanism is conceivable for the change in the molecular structure of synthetic resin, especially soft vinyl chloride resin, upon radiation deterioration. Firstly, it is considered that the plasticizer component is destroyed/decomposed or bleeds out by the irradiation of γ-rays, thereby impairing the flexibility of the soft vinyl chloride resin and deteriorating the strength and elongation of the resin. Secondly, a mechanism may be considered in which the vinyl chloride resin polymers have cross-linking points with each other due to the irradiation of γ-rays and become brittle even when the resin is cured, and the strength and elongation of the resin deteriorate. Thirdly, as the cross-linking of the vinyl chloride resin progresses, the resin cannot hold the plasticizer inside, and the plasticizer bleeds out of the resin, which accelerates the curing of the resin and increases the strength of the resin. The mechanism of deterioration of elongation and elongation is considered.

In the radiation resistant vinyl chloride resin composition of the above-mentioned embodiment, by mixing a predetermined amount of phenyl ether-based fats and oils, the phenyl ether-based fats and oils also function as a kind of plasticizer in the vinyl chloride resin composition, Increase the flexibility of. Further, since phenyl ether-based fats and oils have a benzene ring and are relatively hard to be decomposed by γ-ray irradiation, it is possible to suppress decomposition of a plasticizer component by γ-ray irradiation, which is the first deterioration mechanism. Contribute to.

Further, it is difficult to mix a phenyl ether-based oil/fat into a vinyl chloride resin composition in a large amount (for example, 20 parts or more), and other plasticizers may be used in combination. It is easier to escape from the vinyl chloride resin than a substance (for example, DOP) generally used as an agent. Therefore, in the vinyl chloride resin composition, phenyl ether-based fats and oils are more likely to bleed out than other plasticizers, and more phenyl ether-based fats and oils are more likely to be present on the surface of the molded article of the resin composition. As a result, phenyl ether-based fats and oils that are difficult to decompose by γ-ray irradiation receive γ-rays on the surface of the molded product, as if it were a protective film, and the progress of crosslinking of the vinyl chloride resin inside the molded product and other plasticizers. I suspect that it may act to delay the decomposition of. That is, the phenyl ether-based oil and fat also contributes to the suppression of the second deterioration mechanism and the third deterioration mechanism.

From the viewpoint of increasing the decomposition resistance of phenyl ether-based oils and fats against γ-rays, phenyl ether-based oils and More preferably. Further, the phenyl ether-based fats and oils are more preferably alkyl diphenyl ether-based fats and oils or polyphenyl ether-based fats and oils from the viewpoint that they are relatively easy to be blended with a vinyl chloride resin and have high resistance to γ-rays.

In addition to the phenyl ether-based fats and oils, if a benzoic acid-based plasticizer of 20 parts by weight or more and 110 parts by weight or less is added to 100 parts by weight of the vinyl chloride resin, the benzoic acid-based plasticizer having a benzene ring can be converted into γ Since the decomposition resistance to irradiation is high, it contributes to suppressing the decomposition of the plasticizer component due to the irradiation of γ rays, which is the first deterioration mechanism, and further suppresses the deterioration of the strength and elongation of the resin.

Further, when carbon black or graphite powder is contained in an amount of 10 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the vinyl chloride resin, the carbon black or the graphite powder causes crosslinking between polymer chains of the vinyl chloride resin. It works to inhibit, contributes to the suppression of the second and third deterioration mechanisms, and further suppresses the deterioration of the strength and elongation of the resin. From the viewpoint of more effectively inhibiting the crosslinking between the vinyl chloride resin polymers, it is more preferable to include graphite powder.

Then, by using the radiation-resistant vinyl chloride resin composition of the above-mentioned embodiment and configuring the flexible hose such that the radiation-resistant vinyl chloride resin composition is contained in the hose wall, the absorbed dose is as high as mega gray. It is possible to obtain a flexible hose capable of maintaining a certain level of strength and flexibility even in an environment where a high level of γ-ray irradiation is received. Such a flexible hose is useful in a nuclear facility or a site of decommissioning work. The radiation-resistant vinyl chloride resin composition may be used for the hose wall, and the hose wall may be entirely composed of the radiation-resistant vinyl chloride resin composition, or may be a metal foil or other film-shaped material or film-shaped material. A radiation resistant vinyl chloride resin composition may be used as a material for forming a part of the layer of the hose wall having a laminated structure together with the material.

Similarly, the flexible tube formed of the radiation resistant vinyl chloride resin composition of the above embodiment has a certain level of strength and flexibility even in an environment where a high level of γ-ray irradiation with an absorbed dose of the order of mega gray is received. It can be maintained. It should be noted that such a flexible tube may be integrated with a reinforcing body or a layer made of another material may be provided.

The radiation resistance characteristics of the radiation resistant vinyl chloride resin composition to γ-ray irradiation are illustrated by the following examples.
Tables 1 to 4 show formulation examples of each example and reference example and changes in physical properties before and after γ-ray irradiation.
The vinyl chloride resin compositions having the formulations of the respective examples and reference examples were kneaded by rolls so that the components of the formulation were uniformly dispersed. In addition, all the units of the formulation in the table are parts by weight. The compounding materials in the table will be described below.

(Vinyl chloride resin)
The types of vinyl chloride resin (PVC) are as follows.
PVC (4500) means a polyvinyl chloride resin having an average degree of polymerization of 4500, and the numerical value in parentheses () indicates the average degree of polymerization.
Plectomer GX is a kind of a graft polymer of a vinyl chloride monomer and another monomer component, and is a resin obtained by completely graft-copolymerizing an acrylic resin with a vinyl chloride resin. This resin is sold as a Plectomer series by Kaneka Corporation.
TG-40 is a kind of graft polymer of vinyl chloride monomer and other monomer components, and is a graft copolymer obtained by graft polymerization of vinyl chloride onto EVA (ethylene/vinyl acetate copolymer) as a trunk. is there. This resin is sold by Sekisui Chemical Co., Ltd. as a PVC-TG series.

(Plasticizer)
The types of plasticizers are as follows.
DOP is dioctyl phthalate.
PB-3A and PB-3 are benzoic acid plasticizers and are sold by DIC Corporation under the product name of Monosizer.

(Phenyl ether oil and fat)
The types of phenyl ether oils and fats are as follows.
Hirad RA-15 and RA-100 are alkyl diphenyl ether-based oils and fats, and are sold by MORESCO Co., Ltd. as lubricating oils and greases.
Hirad RP-42R is a polyphenyl ether oil and fat, and is sold by MORESCO Co., Ltd.

(Carbon powder)
The types of carbon black or graphite powder are as follows.
CB (acetylene) is acetylene black. It is a relatively large diameter carbon black sold as Denka Black HS-100 by Denka Corporation.
CB#960 is a pyrolytic carbon black, and is a relatively small diameter carbon black sold by Mitsubishi Chemical Corporation under the model #960.
Graphite WF-7 is expanded graphite sold by Fuji Graphite Industry Co., Ltd.

(Other compounding agents)
ESO (epoxidized soybean oil) is blended as a heat stabilizer.
A barium/zinc-based stabilizer is added as a stabilizer.
A polyester processing aid is added as a processing aid.
Stearic acid is added as a lubricant.

No. 5 type dumbbells for tensile test were prepared from the vinyl chloride resin composition of each example reference example, and the hardness and tensile test of the resin were performed before and after irradiation with γ-ray to measure the mechanical properties. The resin hardness was measured by using a durometer according to JIS K7215.

(Tensile test)
Based on JIS K7161, elongation deformation was applied to a predetermined dumbbell at a tensile speed of 200 mm/min, and the maximum tensile stress, the tensile 100% modulus (tensile 100M), and the tensile elongation were measured.

(Γ-ray irradiation)
The sample (dumbbell) whose physical properties were to be measured after being exposed to γ rays was irradiated with γ rays. The irradiation with γ-rays was carried out by using cobalt 60 as a radiation source and γ-rays at room temperature in the atmosphere so that the dose rate was 8.35 kGy/h.
The samples shown in Tables 1 to 3 were irradiated with γ-rays for about 360 hours so that the absorbed dose was 3 MGy, and the samples shown in Table 4 had an absorbed dose of 2 MGy. Irradiation was performed for about 240 hours.

The test results are summarized below.
In each of the Examples and Reference Examples, the soft vinyl chloride resin composition has preferable hardness, strength and elongation before γ-ray irradiation.

According to Table 4, in each of the examples (Examples 20 to 23) in which the phenyl ether-based fats and oils are blended, the residual rate of tensile elongation after irradiation with 2MGy is significantly improved as compared with the reference example. I understand. Further, as compared with these Examples, the combined use of the benzoic acid-based plasticizer and the phenyl ether-based fats and oils (Examples 22 and 23) is particularly effective in improving the tensile elongation residual rate. Recognize. Further, comparing Example 22 and Example 23, it can be seen that the phenyl ether-based fats and oils may be alkyldiphenyl ether-based fats and oils or polyphenyl ether-based fats and oils.

The following can be seen from Tables 1 to 3.
If phenyl ether oils and fats are blended as in Examples 1 to 3, the tensile elongation can be maintained near 100% even after irradiation with 3 MGy. This is a fairly high level of radiation resistance characteristics for a vinyl chloride resin composition.

When a benzoic acid plasticizer and a phenyl ether oil and fat are used in combination as in Examples 5 to 13, the residual rate of tensile elongation after irradiation with 3 MGy is further increased.

When carbon black or graphite powder and phenyl ether oil and fat are used in combination as in Examples 4, 7 and 14 to 18, the residual rate of tensile elongation after irradiation with 3 MGy is further increased.
Among them, when carbon black or graphite powder is used in combination with benzoic acid plasticizer and phenyl ether oil, the tensile elongation after irradiation with 3MGy exceeds 150% to 200% as in Examples 14 to 18. , Higher tensile elongation is maintained.
Further, comparing Example 14, Example 17, and Example 18, it can be seen that the compounding of graphite powder is particularly effective in maintaining the tensile elongation after irradiation with 3 MGy.

Also, comparing Examples 6, 8 and 9, it can be seen that the average degree of polymerization of the vinyl chloride resin is slightly more than 2500. Further, looking at Examples 6, 8 and 9, Examples 10 and 11, etc., even if the type or blend of the vinyl chloride resin as the base changes, the phenyl ether oil and fat are blended. It can be understood that the effect of suppressing the deterioration of physical properties after γ-ray irradiation due to the above is approximately exhibited.

In addition, for each of the examples shown in Table 3, each sample was immersed in THF (tetrahydrofuran) after irradiation with an absorbed dose of 3 MGy of γ-rays, and it was tested whether or not the sample was dissolved and to what extent. In Examples 12 and 13 in which carbon black was not added, the samples after the γ-ray irradiation were substantially insoluble. That is, in these samples, it means that the polymer chains of the vinyl chloride resin were cross-linked with each other by the irradiation of γ-rays and became insoluble in the solvent. On the other hand, in Examples 14 to 19 in which carbon black or graphite powder was blended, the sample after γ-ray irradiation was slightly dissolved in THF, which resulted in “fine dissolution”. That is, the incorporation of carbon black or graphite powder prevented the polymer chains of the vinyl chloride resin from cross-linking.

The radiation resistant vinyl chloride resin composition can be used, for example, in a flexible hose or a flexible tube, can be used in an environment exposed to radiation, and has a high industrial utility value.

1 flexible hose 2 hose wall 3 spiral reinforcement

Claims (4)

100 parts by weight of vinyl chloride resin,
20 parts by weight or more and 110 parts by weight or less of a benzoic acid plasticizer,
1 to 15 parts by weight of phenyl ether oil and fat,
And contains
Duro A hardness before γ-ray irradiation is 50 HDA or more and 95 HDA or less ,
The elongation when the absorption amount of γ-ray reaches 3 MGy is 100% or more,
Radiation resistant vinyl chloride resin composition. The radiation resistant vinyl chloride resin composition according to claim 1, containing 10 parts by weight or more and 50 parts by weight or less of carbon black or graphite powder. A flexible hose containing the radiation resistant vinyl chloride resin composition according to claim 1 or 2 in a hose wall. A flexible tube formed from the radiation resistant vinyl chloride resin composition according to claim 1 .

Images