JPH0933691A - Neutron shielding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve shielding ability and transparency in good balance by using an ethylene-annular olefin random copolymer in which ethylene and specific annular olefin are copolymerized. SOLUTION: As a neutron shielding material, an ethylene-annular olefin random copolymer obtained, by copolymerizing ethylene and annular olefin represented by formula I or II is used, (in the formula I, n is 0 or 1, m is 0 or positive integer, q is 0 or 1, R<1> to R<18> and R<a> and R<b> are hydrocarbon group independently replaceable by hydrogen atom, halogen atom or halogen. In the formula II, p and q are 0 or positive integers, m and n are 0, 1 are 2, R<1> to R<19> are hydrocarbon group or alkoxy replaceable by hydrogen atom, halogen atom or halogen.) By its use, a neutraon shield material superior in transparency and neutron shielding ability and with high hydrogen atom density can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a neutron shielding material, and more particularly, it has excellent neutron shielding properties, is transparent, and facilitates observation of contents to be shielded such as a radiation source or an irradiation object through the shielding material. Regarding neutron shielding material.

[0002]

BACKGROUND OF THE INVENTION When working in a nuclear facility or handling radioactive materials, it is necessary to shield radiation to protect the human body.

In recent years, the shielding of radiation has also been required in the field of electronic industry. In particular, integrated circuits (I
The very small amount of α-rays emitted from uranium, thorium, etc. contained in the ceramics and glass used for the package of C) sporadically generate hole-electron pairs in the substrate, and the function of the integrated circuit is improved. There is also a risk of damage.

Among these radiations, there is a great need to shield γ rays and neutron rays, which have a particularly high substance penetrating power. Examples of conventionally known materials capable of forming such a neutron shielding material include polymethylmethacrylate obtained by copolymerizing metal lead, methacrylate and lead acrylate, and concrete materials (Japanese Patent Laid-Open No. 53-9996, Kaihei 2-189
In addition to water, hydrocarbon compounds containing a large amount of hydrogen in the molecule, such as polyethylene, polybutene, liquid paraffin, acrylic resin and the like (see JP-A-5-27088).

However, as described in Japanese Patent Application Laid-Open No. 2-189350, polymethylmethacrylate obtained by copolymerizing metal lead, methacrylate, and lead acrylate does not contain a hydrogen atom or hydrogen. Even if it contains atoms, its content is small, and it is not sufficient to shield neutron rays having high penetrating power, and it is usually required to use it together with other shielding materials. In addition, all of these shielding materials including concrete are opaque or poor in transparency.

The neutron shielding ability of water, polyethylene, polybutene, liquid paraffin, acrylic resin, etc. is also described in JP-A-5-27088. For example, water has a fluidity at room temperature. It is too expensive and may easily flow out due to damage to the shielding container that contains water. Polyethylene and polybutene are solid at room temperature but inferior in transparency, which is inconvenient for observing the shielding contents. There was a problem with.

Liquid paraffin may leak out like water, has a low hydrogen density, is inferior in shielding property against radiation, and may cause ignition when heated. An acrylic resin is excellent in transparency, can be polymerized and cured in a mold, and is excellent in molding processability, but has a lower hydrogen atom density than water and paraffin hydrocarbons and is inferior in shielding ability.

Further, in the above-mentioned Japanese Patent Application Laid-Open No. 5-27088, a transparent high speed film made of a transparent polymer having a viscosity average molecular weight of 20,000 to 80,000 and a hydrogen atom density of 7.0 × 10 ²² pieces / cm ³ or more. A neutron shielding material is disclosed. As such a transparent polymer, its "means for solving problems"
In the section of, polyisobutylene is mentioned, and this polyisobutylene is other transparent member, that is, acrylic resin
It is described that it may be used by laminating it with a transparent resin such as polystyrene, polybutadiene, polyvinyl chloride, polyvinylidene chloride, cellophane, or an inorganic substance such as glass.

However, the polyisobutylene described in this publication has room for further improvement in terms of transparency. Further, Japanese Patent Publication No. 62-49305 discloses a density of 0.9.
100 parts by weight of a polyethylene resin having a molecular weight of 30,000 or more and 50 g / cc or more, and an inorganic boron compound 3
A neutron shielding material comprising 50 to 750 parts by weight is disclosed. However, this neutron shielding material has a problem that it is inferior in transparency like polyethylene.

Japanese Unexamined Patent Publication (Kokai) No. 2-189350 discloses that lead borate is added in an amount of 0.1 to 100 parts by weight of hydrocarbon rubber.
A rubber composition containing 60 parts by weight and excellent in neutron shielding property is disclosed, and as a hydrocarbon rubber, ethylene / propylene rubber, hydrogenated natural rubber, hydrogenated isoprene rubber, hydrogenated styrene / butadiene rubber, butyl rubber,
Hydrogenated styrene-isoprene rubber is mentioned.
However, in all cases, improvement in transparency is required.

As described above, the conventional neutron shielding material has a problem that it is inferior in neutron shielding ability or inferior in transparency, and a neutron shielding material excellent in both neutron shielding ability and transparency is , Not yet found.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and an object of the present invention is to provide a neutron shielding material having a good balance of both neutron shielding ability and transparency. .

[0013]

SUMMARY OF THE INVENTION The neutron shielding material according to the present invention has the following [A
-1], [A-2], [A-3], and [A-4].

[A-1] Ethylene and the following formula [I] or [I
I] an ethylene / cyclic olefin random copolymer obtained by copolymerizing with a cyclic olefin;

[0015]

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(In the formula [I], n is 0 or 1, and m is
Is 0 or a positive integer; q is 0 or 1;
^{1 to} R ¹⁸ and R ^a and R ^b are each independently a hydrogen atom, a halogen atom or a hydrocarbon group optionally substituted with halogen, and R ^{15 to} R ¹⁸ are bonded to each other to form a monocyclic or polycyclic ring. And the monocyclic or polycyclic ring may have a double bond, and may form an alkylidene group with R ¹⁵ and R ¹⁶ or with R ¹⁷ and R ^18. You may. ),

[0017]

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(In the formula [II], p and q are 0 or a positive integer, m and n are 0, 1 or 2, and R ¹
To R ¹⁹ are each independently a hydrogen atom, a halogen atom, a hydrocarbon group or an alkoxy group which may be substituted with halogen, and a carbon atom to which R ⁹ or R ¹⁰ is bonded and R ¹³ are bonded to each other. May be directly or via an alkylene group having 1 to 3 carbon atoms, or may be bonded to the carbon atom to which R ¹¹ is bonded. When n = m = 0, R ¹⁵ and R ¹² or R ^{12 15} and R ¹⁹ may combine with each other to form a monocyclic or polycyclic aromatic ring. ), [A-
2] A ring-opening polymer or copolymer of the cyclic olefin represented by the above formula [I] or [II], [A-3] a hydride of the above ring-opening polymer or copolymer [A-2], And [A-4] Above [A-
1], [A-2] or [A-3] graft modified product.

In the present invention, the above cyclic olefin resin is an ethylene / cyclic olefin random copolymer [A-1].
It is preferred that Such a neutron shielding material is excellent in both neutron shielding ability and transparency in a well-balanced manner.

Since such a neutron shielding material is transparent as described above, it is easy to observe the contents to be shielded such as a radiation source or an irradiation object through the shielding material, and it is substantially solid at room temperature. It has fluidity by heating and can be easily applied to an object to be shielded having a complicated shape.

[0021]

DETAILED DESCRIPTION OF THE INVENTION The neutron shielding material according to the present invention will be specifically described below. The neutron shielding material according to the present invention is formed of the following specific cyclic olefin resin.

First, the cycloolefin resin forming the neutron shielding material according to the present invention will be described below. In the present invention, as the cyclic olefin-based resin, a random copolymer of [A-1] ethylene and a cyclic olefin represented by the following formula [I] or [II], [A-2] the following formula [I] or [I
[I]] ring-opening polymer or copolymer of cyclic olefin, [A-3] hydride of [A-2] above ring-opening polymer or copolymer, and [A-4] above [A-4] -1], [A-2] or at least one selected from the graft modified products of [A-3].

The softening temperature (TMA) of the cyclic olefin resin used in the present invention measured by a thermal mechanical analyzer is 0 ° C. or higher, preferably 10 to 200 ° C.
More preferably, it is 10 to 180 ° C., and the glass transition point (Tg) is −10 ° C. to 190 ° C., preferably 0 to 170.
It is desirable that the temperature is ° C.

The crystallinity of the cyclic olefin resin used in the present invention is 0 to 20 as measured by the X-ray diffraction method.
%, Preferably 0 to 2%. The intrinsic viscosity [η] of the cyclic olefin-based resin measured in decalin at 135 ° C. is 0.05 to 10 dl / g, and preferably 0.0 to 10 dl / g.
3-2.0 dl / g, more preferably 0.4-1.2 dl / g
It is desirable that

First, the cyclic olefin represented by the formula [I] or [II] which forms the cyclic olefin resin used in the present invention will be described. Cyclic olefin

[0026]

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In the above formula [I], n is 0 or 1,
m is 0 or a positive integer, and q is 0 or 1.
When q is 1, R ^a and R ^b are each independently the following atoms or hydrocarbon groups. When q is 0, each bond is bonded to form a 5-membered ring. Form.

R ^{1 to} R ¹⁸ and R ^a and R ^b are each independently a hydrogen atom, a halogen atom or a hydrocarbon group. Here, the halogen atom is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.

As the hydrocarbon group, there may be mentioned, independently of each other, an alkyl group usually having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 15 carbon atoms, and an aromatic hydrocarbon group.

More specifically, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an amyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group and an octadecyl group, and a cycloalkyl group. Examples thereof include a cyclohexyl group, and examples of the aromatic hydrocarbon group include a phenyl group and a naphthyl group.

These hydrocarbon groups may be substituted with a halogen atom. Further, in the above formula [I], R
^{15 to} R ¹⁸ may be bonded to each other (together with each other) to form a monocyclic or polycyclic ring, and the monocyclic or polycyclic ring thus formed has a double bond. Is also good. The monocyclic or polycyclic rings formed here are specifically exemplified below.

[0032]

[Chemical 6]

In the above exemplification, the carbon atoms numbered 1 or 2 are each R in the formula [I].
Represents a carbon atom to which ¹⁵ (R ¹⁶ ) or R ¹⁷ (R ¹⁸ ) is bonded. Further, R ¹⁵ and R ¹⁶ or R ¹⁷ and R ¹⁸ may form an alkylidene group. Such an alkylidene group is usually an alkylidene group having 2 to 20 carbon atoms, and specific examples of such an alkylidene group include an ethylidene group, a propylidene group and an isopropylidene group.

[0034]

[Chemical 7]

In the formula [II], p and q are 0 or a positive integer, and m and n are 0, 1 or 2. Also R
^{1 to} R ¹⁹ are each independently a hydrogen atom, a halogen atom,
It is a hydrocarbon group or an alkoxy group.

The halogen atom has the same meaning as the halogen atom in the above formula [I]. Further, as the hydrocarbon group, each independently an alkyl group having 1 to 20 carbon atoms,
Examples thereof include a halogenated alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 15 carbon atoms or an aromatic hydrocarbon group. More specifically, as the alkyl group,
A methyl group, an ethyl group, a propyl group, an isopropyl group, an amyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, and an octadecyl group; a cycloalkyl group includes a cyclohexyl group; an aromatic hydrocarbon group; Examples thereof include an aryl group and an aralkyl group, specifically, a phenyl group, a tolyl group, a naphthyl group, a benzyl group and a phenylethyl group.

Examples of the alkoxy group include a methoxy group, an ethoxy group and a propoxy group.
These hydrocarbon groups and alkoxy groups may be substituted with a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.

Here, the carbon atom to which R ⁹ and R ¹⁰ are bonded and the carbon atom to which R ¹³ is bonded or the carbon atom to which R ¹¹ is bonded are either directly or having 1 to 10 carbon atoms.
And 3 may be bonded via an alkylene group. That is, when the above two carbon atoms are bonded via an alkylene group, the groups represented by R ⁹ and R ¹³ or the groups represented by R ¹⁰ and R ¹¹ cooperate with each other, It forms an alkylene group of any one of a methylene group (-CH _2- ), an ethylene group (-CH ₂ CH _2- ) or a propylene group (-CH ₂ CH ₂ CH _2- ).

Further, when n = m = 0, R ¹⁵ and R ¹² or R ¹⁵ and R ¹⁹ may combine with each other to form a monocyclic or polycyclic aromatic ring. In this case, as the monocyclic or polycyclic aromatic ring, for example, the following n = m = 0
In the above, a group in which R ¹⁵ and R ¹² further form an aromatic ring can be mentioned.

[0040]

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Here, q has the same meaning as q in the formula [II]. The cyclic olefin represented by the above formula [I] or [II] is more specifically exemplified below.

[0042]

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(In the above formula, the numbers 1 to 7 represent the position number of carbon.) And a derivative obtained by substituting the bicyclo [2.2.1] -2-heptene with a hydrocarbon group. Examples of the hydrocarbon group include 5-methyl, 5,6-dimethyl, 1-methyl, 5-ethyl, 5-n-butyl, 5-isobutyl, 7-methyl, 5-phenyl, 5-methyl-5 -Phenyl, 5-benzyl, 5
-Tolyl, 5- (ethylphenyl), 5- (isopropylphenyl), 5- (biphenyl), 5- (β-naphthyl), 5- (α
-Naphthyl), 5- (anthracenyl), 5,6-diphenyl and the like.

As other derivatives, cyclopentadiene-acenaphthylene adduct, 1,4-methano-1,4,4a, 9a-
Tetrahydrofluorene, 1,4-methano-1,4,4a, 5,10,10a
-Bicyclo [2.2.1] such as hexahydroanthracene
2-heptene derivatives and the like.

Tricyclo [4.3.0.1 ^2,5 ] -3-decene, 2-
Tricyclo [4.3.0.1 ^2,5 ] -3-decene derivatives such as methyltricyclo [4.3.0.1 ^2,5 ] -3-decene and 5-methyltricyclo [4.3.0.1 ^2,5 ] -3-decene; Tricyclo [4.4.0.1
^2,5 ] -3-undecene, 10-methyltricyclo [4.4.0.1
^2,5 ] -3-undecene and other tricyclo [4.4.0.1 ^2,5 ] -3
-Undecene derivative.

[0046]

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(In the above formula, the numbers 1 to 12 represent the position number of carbon) and derivatives thereof in which a hydrocarbon group is substituted. Examples of this hydrocarbon group include 8-methyl,
8-ethyl, 8-propyl, 8-butyl, 8-isobutyl, 8-
Hexyl, 8-cyclohexyl, 8-stearyl, 5,10-dimethyl, 2,10-dimethyl, 8,9-dimethyl, 8-ethyl-9-methyl, 11,12-dimethyl, 2,7,9-trimethyl, 2,7-dimethyl-9-ethyl, 9-isobutyl-2,7-dimethyl, 9,11,12-trimethyl, 9-ethyl-11,12-dimethyl, 9-isobutyl-1
1,12-dimethyl, 5,8,9,10-tetramethyl, 8-ethylidene, 8-ethylidene-9-methyl, 8-ethylidene-9-ethyl,
8-ethylidene-9-isopropyl, 8-ethylidene-9-butyl, 8-n-propylidene, 8-n-propylidene-9-methyl, 8
-n-propylidene-9-ethyl, 8-n-propylidene-9-isopropyl, 8-n-propylidene-9-butyl, 8-isopropylidene, 8-isopropylidene-9-methyl, 8-isopropylidene-9- Ethyl, 8-isopropylidene-9-isopropyl, 8-isopropylidene-9-butyl, 8-chloro, 8-bromo, 8-fluoro, 8,9-dichloro, 8-phenyl, 8-methyl
-8-phenyl, 8-benzyl, 8-tolyl, 8- (ethylphenyl), 8- (isopropylphenyl), 8,9-diphenyl, 8- (biphenyl), 8- (β-naphthyl), 8- ( α-naphthyl), 8- (anthracenyl), 5,6-diphenyl and the like.

Still another derivative is an adduct of (cyclopentadiene-acenaphthylene adduct) with cyclopentadiene. Pentacyclo [6.5.1.1
^3,6. 0 ^2,7 .0 ^9,13 ] -4-Pentadecene and its derivatives.

[0049] pentacyclo [7.4.0.1 ^2,5 .1 ^9,12 .0 ^8,13]
-3-pentadecene, and derivatives thereof. Pentacyclo ^{[6.5.1.1 3,6 .0 2,7 .0 9,13]} -4,10- penta octadecadienoic Penta cyclopentadiene octadecadienoic compound such.

[0050] pentacyclo [8.4.0.1 ^2,5 .1 ^9,12 .0 ^8,13]
-3-hexadecene and its derivatives. Pentacyclo ^{[6.6.1.1 3,6 .0 2,7 .0 9,14]} -4- hexadecene, and derivatives thereof.

[0051] hexacyclo [6.6.1.1 ^3,6 .1 ^10,13 .0 ^2,7 .0
^9,14] -4-heptadecene and derivatives thereof. Heptacyclo ^{[8.7.0.1 2,9 .1 4,7 .1 11,17 .0} 3,8 .0 12,16] -5- eicosene, and derivatives thereof.

[0052] heptacyclo [8.8.0.1 ^2,9 .1 ^4,7 .1 ^11,18 .0
^3,8 .0 ^12,17] -5-heneicosene, and a derivative thereof.
Octacyclo ^{[8.8.0.1 2,9 .1 4,7 .1 11,18 .1} 13,16 .0 3,8 .0
^12,17 ] -5-docosene and derivatives thereof.

[0053] Nonashikuro [10.9.1.1 ^4,7 .1 ^13,20 .1 ^15,18.
0 ^2,10 .0 ^3,8 .0 ^12,21 .0 ^14,19] -5-pentacosene and derivatives thereof. Nonashikuro [10.10.1.1 ^5,8 .1 ^14,21.
1 ^{16, 19} .0 ^2,11 .0 ^4,9 .0 ^{13, 22} .0 ^{15, 20]} -6-hexacosenoic,
And its derivatives.

Specific examples of the cyclic olefin represented by the general formula [I] or [II] are shown above, but more specific structural examples of these compounds are described in Japanese Patent Application No. Hei. -196475, paragraph number [003
The structural examples of the cyclic olefins shown in 2] to [0054] can be used.

The cyclic olefin represented by the above general formula [I] or [II] can be produced by subjecting cyclopentadiene and olefins having a corresponding structure to a Diels-Alder reaction.

These cyclic olefins may be used alone or in combination of two or more. The cyclic olefin resin used in the present invention can be prepared by using the cyclic olefin represented by the formula [I] or [II] as described above, for example, in JP-A-60-168708, JP-A-61-120816 and JP-A-61-120816.
-115912, 61-115916, 61-271308, 61-2722
Nos. 16, 62-252406, 62-252407, etc., according to the method proposed by the present applicant, and by appropriately selecting conditions, it can be produced.

[A-1] Ethylene / Cyclic Olefin Random
The copolymer [A-1] ethylene / cyclic olefin random copolymer usually has a constitutional unit derived from ethylene from 30 to 9
It contains structural units derived from cyclic olefins in an amount of 0 mol%, preferably 40 to 85 mol%, usually 10 to 70 mol%, preferably 15 to 60 mol%. The ethylene composition and cyclic olefin composition are ¹³
Measured by C-NMR.

In this [A-1] ethylene / cyclic olefin random copolymer, the constitutional units derived from ethylene and the constitutional units derived from cyclic olefin as described above are randomly arranged and bonded. , Has a substantially linear structure. The fact that the copolymer is substantially linear and does not have a substantially gel-like cross-linked structure means that when the copolymer is dissolved in an organic solvent, the solution contains an insoluble component. You can confirm by not having. For example, when the intrinsic viscosity [η] is measured, this copolymer is
It can be confirmed by being completely dissolved in decalin at 5 ° C.

In the [A-1] ethylene / cyclic olefin random copolymer used in the present invention, the above formula [I]
Alternatively, at least a part of the cyclic olefin represented by [II] is considered to constitute the repeating unit represented by the following formula [III] or [IV].

[0060]

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In the formula [III], n, m, q, R ¹ to
R ¹⁸ and R ^a and R ^b have the same meaning as in formula [I].

[0062]

[Chemical 12]

In the formula [IV], n, m, p, q and R ^{1 to} R ¹⁹ have the same meanings as in the formula [II]. Further, the [A-1] ethylene / cycloolefin random copolymer used in the present invention has a structural unit derived from another copolymerizable monomer, if necessary, within a range not impairing the object of the present invention. May be.

Examples of such other monomers include olefins other than the above-mentioned ethylene or cyclic olefins. Specifically, propylene, 1-butene, 1-pentene, 1-hexene, 3- Methyl-1-butene, 3-
Methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1
-Pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene , 1-decene, 1-
Α- having 3 to 20 carbon atoms such as dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene
Olefin, cyclobutene, cyclopentene, cyclohexene, 3,4-dimethylcyclopentene, 3-methylcyclohexene, 2- (2-methylbutyl) -1-cyclohexene and cyclooctene, 3a, 5,6,7a-tetrahydro-4,7-methano Cycloolefins such as -1H-indene, 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 1,7-octadiene, dicyclopentadiene and 5-vinyl-2 Non-conjugated dienes such as -norbornene.

These other monomers can be used alone or in combination. [A-1] In the ethylene / cyclic olefin random copolymer, the structural unit derived from the other monomer as described above is usually 20 mol% or less, preferably 10 mol% or less.
It may be contained in the following amounts.

The [A-1] ethylene / cyclic olefin random copolymer used in the present invention comprises ethylene and a compound of the formula [I].
Alternatively, it can be produced by the production method disclosed in the above publication using a cyclic olefin represented by [II]. Among these, this copolymerization is carried out in a hydrocarbon solvent, and a catalyst formed from a vanadium compound and an organoaluminum compound soluble in the hydrocarbon solvent is used as a catalyst for [A-1] ethylene / cyclic olefin random copolymerization. It is preferred to produce a polymer.

In this copolymerization reaction, a solid group IVB metallocene catalyst can be used. Where solid IV
The group B metallocene-based catalyst is a catalyst comprising a transition metal compound containing a ligand having a cyclopentadienyl skeleton, an organic aluminum oxy compound, and an organic aluminum compound optionally added. Here, the group VI transition metal is zirconium, titanium or hafnium, and these transition metals have at least one ligand having a cyclopentadienyl skeleton. here,
Examples of the ligand having a cyclopentadienyl skeleton include a cyclopentadienyl group or an indenyl group, a tetrahydroindenyl group and a fluorenyl group which may be substituted by an alkyl group. These groups may be bonded via another group such as an alkylene group. Further, ligands other than the ligand having a cyclopentadienyl skeleton include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group and the like.

Further, as the organoaluminum oxy compound and the organoaluminum compound, those generally used for the production of olefin resins can be used. Such a solid group IVB metallocene catalyst is described in, for example, JP-A-61-221206, JP-A-64-106, and JP-A-2-173112.

[A-2] Ring-Opening Polymer of Cyclic Olefin or
In the ring-opening polymer or ring-opening copolymer of the copolymer cyclic olefin, at least a part of the cyclic olefin represented by the above formula [I] or [II] is represented by the following formula [V] or [VI]. It is considered that they constitute the repeating unit.

[0070]

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In the formula [V], n, m, q and R ¹
To R ¹⁸ and R ^a and R ^b have the same meanings as in formula [I].

[0072]

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In the formula [VI], n, m, p, q and R ^{1 to} R ¹⁹ have the same meanings as in the formula [II]. Such a ring-opening polymer or a ring-opening copolymer can be produced by the production method disclosed in the above-mentioned gazette. It can be produced by polymerization or copolymerization below.

As such a ring-opening polymerization catalyst, a catalyst comprising a metal halide selected from ruthenium, rhodium, palladium, osmium, indium or platinum, a nitrate or an acetylacetone compound and a reducing agent, or titanium, A catalyst composed of a halide of a metal selected from palladium, zirconium, molybdenum or the like or an acetylacetone compound and an organoaluminum compound can be used.

[A-3] Hydrogenation of Ring-Opening Polymer or Copolymer
The hydride of the ring-opening polymer or copolymer [A-3] used in the present invention is obtained by converting the ring-opening polymer or copolymer [A-2] obtained as described above into a conventionally known hydrogen-containing compound. It is obtained by hydrogenation in the presence of an added catalyst.

In the hydride of the [A-3] ring-opening polymer or copolymer, at least a part of the cyclic olefin represented by the formula [I] or [II] is represented by the following formula [VII]
Alternatively, it is considered to have a repeating unit represented by [VIII].

[0077]

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In the formula [VII], n, m, q and R
^{1 to} R ¹⁸ and ^Ra and ^Rb have the same meaning as in formula [I].

[0079]

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In the formula [VIII], n, m, p, q, R
^{1 to} R ¹⁹ have the same meaning as in formula [II]. [A-4] Graft-modified product The graft-modified product of the cyclic olefin resin is the same as the above [A-
1] Ethylene / Cyclic Olefin Random Copolymer, [A-
2] A ring-opening polymer or copolymer of a cyclic olefin, or a graft-modified product of a hydride of the [A-3] ring-opening polymer or copolymer.

As the modifier, unsaturated carboxylic acids are usually used. Specifically, (meth) acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, Unsaturated carboxylic acids such as endocis-bicyclo [2.2.1] hept-5-ene-2,3-dicarboxylic acid (Nadic acid ^TM ), and derivatives of these unsaturated carboxylic acids such as unsaturated carboxylic anhydrides and unsaturated Examples thereof include carboxylic acid halides, unsaturated carboxylic acid amides, unsaturated carboxylic acid imides, and ester compounds of unsaturated carboxylic acids.

Specific examples of the unsaturated carboxylic acid derivative include maleic anhydride, citraconic anhydride, maleenyl chloride, maleimide, monomethyl maleate, dimethyl maleate, and glycidyl maleate.

Among these modifiers, α, β-unsaturated dicarboxylic acids and α, β-unsaturated dicarboxylic acid anhydrides such as maleic acid, nadic acid and anhydrides of these acids are preferably used. These modifiers can be used in combination of two or more.

The modification ratio of the graft-modified product of the cyclic olefin resin used in the present invention is usually preferably 10 mol% or less. Such a graft modified product of a cyclic olefin-based resin can be produced by blending a cyclic olefin-based resin with a modifying agent so as to have a desired modification ratio and then graft-polymerized. It can also be produced by preparing and then mixing this modified product with an unmodified cyclic olefin resin.

In order to obtain a graft-modified product of a cyclic olefin resin from a cyclic olefin resin and a modifier, conventionally known polymer modification methods can be widely applied.
For example, a graft-modified product is obtained by a method of adding a modifier to a molten cyclic olefin-based resin and performing graft polymerization (reaction), or a method of adding a modifier to a solvent solution of the cyclic olefin-based resin and performing a graft reaction. be able to.

Such a graft reaction is usually carried out at 60 to 3
It is carried out at a temperature of 50 ° C. The graft reaction can be performed in the presence of a radical initiator such as an organic peroxide and an azo compound.

A modified product having a modification ratio as described above can be obtained directly by a graft reaction between a cyclic olefin resin and a modifying agent, and a modified product having a high modification ratio can be obtained in advance by a graft reaction between the cyclic olefin resin and a modifying agent. It is also possible to obtain the modified product by diluting the modified product with an unmodified cyclic olefin resin so as to obtain a desired modification ratio.

In the present invention, as the cyclic olefin resin, the above-mentioned [A-1], [A-2], [A-3] and [A-3] are used.
-4] can be used alone, or can be used in combination.

Of these, ethylene / cyclic olefin random copolymer [A-1] is preferably used. The hydrogen atom density of such a cyclic olefin resin is usually
5 × 10 ^{22 to} 9 × 10 ²² pieces / cm ³ , preferably 6 × 1
It is 0 ²² pieces / cm ³ or more.

In the present invention, the neutron shielding material formed from the above cyclic olefin resin may contain other components within the range not impairing the object of the present invention,
For example, additives, other transparent resins (eg acrylic resins, polystyrene, polybutadiene, etc. cited in the background section), rubber components for improving impact strength (eg EPR, EPDM, SBS, SEBS, etc.). other,
(Cited in the background art section), a boron compound, a lead compound and the like may be contained.

In the present invention, in order to produce a neutron shielding material from the above cyclic olefin resin, for example, an injection molding method, a blow molding method, a sheet molding method or the like is appropriately selected to obtain a desired shape. It may be formed into a size. By covering the periphery of the radiation source (neutron source) with the neutron shielding material thus obtained, neutrons can be shielded.

Further, the cyclic olefin resin is heated and melted at a temperature higher than its softening point, for example, a temperature of about 150 to 350 ° C., and directly filled in a place where radiation shielding is required,
The radiation source (neutron source) may be shielded by casting, transfer, extrusion, injection, or the like, or by attaching the cyclic olefin-based resin molded product to cracks, holes, or the like.

As described above, the shape of the neutron shielding material made of the cyclic olefin resin according to the present invention is not particularly limited. The thickness of the neutron shielding material made of the cyclic olefin resin according to the present invention is not particularly limited, but the neutron shielding material can be used with a thickness of, for example, about 0.1 to 8 cm.

By covering the periphery of the radiation source with the neutron shielding material according to the present invention, neutron rays can be shielded, and the contents of the radiation source (neutron source) can be protected through the neutron shielding material. It can be observed directly with the naked eye.

[0095]

INDUSTRIAL APPLICABILITY The neutron shielding material comprising the cyclic olefin resin according to the present invention is excellent not only in transparency but also in high hydrogen atom density and excellent in neutron shielding ability.

[0096]

Next, the present invention will be described in detail with reference to examples.

[0097]

Example 1 [ Neutron shielding material ] As the neutron shielding material, ethylene and tetracyclo [4.4.0.1 ^2,5 . 1 ^{7,1 0]} -3- dodecene (hereinafter abbreviated as "TCD-3") was used a random copolymer of (cyclic olefin resin).

The manufacturing method of this resin is shown below. Production of random copolymer of ethylene and "TCD-3" Supply of "TCD-3" in a cyclohexane solution of "TCD-3" in the polymerization vessel from the upper part of a 1-liter glass polymerization vessel equipped with a stirring blade. It was continuously fed into the polymerization vessel so that the concentration became 40 g / liter. In addition, a cyclohexane solution of VO (0.C ₂ H ₅ ) Cl ₂ was used as a catalyst from the upper part of the polymerization vessel so that the concentration of vanadium in the polymerization vessel was 0.5 mmol / liter of ethyl aluminum sesquichloride [Al A cyclohexane solution of [C ₂ H ₅ ) _1.5 Cl _1.5 ] was continuously fed into each of the polymerization reactors so that the aluminum concentration in the polymerization reactor was 4.0 mmol / liter. Further, ethylene was supplied at a rate of 36.0 liters / hour, nitrogen at 35.0 liters / hour and hydrogen at a rate of 1.0 liter / hour using a bubbling tube in the polymerization system. The copolymerization reaction was carried out while maintaining the polymerization system in which a heating medium was circulated in a jacket attached to the upper part of the polymerization vessel at 10 ° C. The polymerization solution of the copolymer produced by the above-mentioned copolymerization reaction is continuously conducted from the upper part of the polymerization vessel so that the polymerization solution in the polymerization vessel is always 1 liter (that is, the average residence time is 0.5 hours). I pulled it out. After the cyclohexane / isopropyl alcohol (1: 1) mixed solution was added to the extracted polymerization solution to stop the polymerization reaction,
An aqueous solution prepared by adding 5 ml of concentrated hydrochloric acid to 1 liter of water and the polymerization solution were brought into contact with each other at a ratio of 1: 1 using a homomixer under vigorous stirring to transfer the catalyst residue to the aqueous phase. After the catalyst mixed solution was allowed to stand, the aqueous phase was separated and removed, and then washed twice with distilled water to purify and separate the polymerization liquid phase.

Next, the purified and separated polymerization liquid was brought into contact with 3 times the amount of acetone under strong stirring to precipitate a copolymer, and then the solid portion was collected by filtration and thoroughly washed with acetone.

Furthermore, in order to extract the unreacted "TCD-3" present in the copolymer, 40 g of this solid portion was added.
After pouring into acetone to make it 1 liter, 60 ℃
The extraction operation was carried out under the condition of 2 hours. After the extraction treatment, the solid part was collected by filtration, and under a nitrogen stream at 130 ° C and 350 ° C.
It was dried at mmHg for 12 hours.

As described above, the MFR was 30 g / 10 min, the glass transition temperature (Tg) was 80 ° C., the specific gravity was 1.02, and the intrinsic viscosity [η] measured in decalin at 135 ° C. Is 0.65 and the hydrogen atom density is 7.1.
A cycloolefin resin having a density of × 10 ²² pieces / cm ³ was obtained (“TCD-3” content: 28.1 mol%).

A transparent and homogeneous rectangular parallelepiped block made of the resin was produced and irradiated with a neutron beam to examine the neutron shielding ability. As a result, it was found that the neutron shielding ability of the resin having excellent transparency is superior to that of the conventionally known acrylic resin.

Claims (2)

[Claims] 1. The following [A-1], [A-2], [A-3] and [A-
4] A neutron shielding material formed of at least one cyclic olefin resin selected from [4]; [A-1] ethylene and a cyclic olefin represented by the following formula [I] or [II]: Ethylene / cyclic olefin random copolymer obtained by copolymerizing (In the formula [I], n is 0 or 1, m is 0 or a positive integer, q is 0 or 1, R ^{1 to} R ¹⁸ and R ^a and R ^b are each independently hydrogen. An atom, a halogen atom or a hydrocarbon group optionally substituted by halogen, wherein R ^{15 to} R ¹⁸ may be bonded to each other to form a monocyclic or polycyclic ring; It may have a double bond, and R ¹⁵ and R ¹⁶ or R ^15
17 and R ¹⁸ may form an alkylidene group. ), Embedded image (In the formula [II], p and q are 0 or a positive integer,
m and n are 0, 1 or 2, and R ^{1 to} R ¹⁹ are each independently a hydrogen atom, a halogen atom, a hydrocarbon group or an alkoxy group optionally substituted by halogen,
The carbon atom to which R ⁹ or R ¹⁰ is bonded and the carbon atom to which R ¹³ is bonded or the carbon atom to which R ¹¹ is bonded are bonded directly or via an alkylene group having 1 to 3 carbon atoms. When n = m = 0, R ¹⁵ and R ¹² or R ¹⁵ and R ¹⁹ may be bonded to each other to form a monocyclic or polycyclic aromatic ring. ), [A-2] The ring-opening polymer or copolymer of the cyclic olefin represented by the above formula [I] or [II], [A-3] The above ring-opening polymer or copolymer [A-2 ], And [A-4] a graft-modified product of the above [A-1], [A-2] or [A-3]. 2. The neutron shielding material according to claim 1, wherein the cyclic olefin resin [A] is an ethylene / cyclic olefin random copolymer [A-1].