JP2016029154A - Polyurethane resin-formable composition for radiation shielding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyurethane resin-formable composition for a radiation shielding material which is excellent in workability and provides excellent radiation shielding properties to a molded article.SOLUTION: A polyurethane resin-formable composition for a radiation shielding material contains polyol, polyisocyanate and an inorganic filler having a true specific gravity of 4.0-6.0. A polyurethane resin molded article for a radiation shielding material is obtained by reacting and curing the polyurethane resin-formable composition for the radiation shielding material, and molding the cured composition. A radiation shielding material is obtained by working the polyurethane resin molded article for the radiation shielding material.SELECTED DRAWING: None

Description

  The present invention relates to a polyurethane resin-forming composition for radiation shielding material, which is excellent in workability. More specifically, the present invention relates to a polyurethane resin-forming composition for a radiation shielding material that imparts radiation shielding performance to a molded product obtained by reaction curing and molding the composition.

In order to simultaneously shield γ rays and neutron rays in radiation, a method in which a filler having a high density is contained in a resin having a high hydrogen atom concentration is generally used. In order to shield neutron beams, polyethylene and paraffin with high hydrogen atom concentration can be mentioned. However, thermosetting resins such as epoxy resins are used because large energy is required for melting and workability is poor (patent document) 1).
Moreover, in order to shield a gamma ray, fillers with high specific gravity, such as tungsten and lead, are often used and contain these.

JP-A-6-180389

However, the technique described in Patent Document 1 is disadvantageous for on-site construction because the epoxy resin has a high viscosity and the concentration of the γ-ray shielding material cannot be increased, and the curing time is slow. In addition, tungsten is expensive as a γ-ray shielding material, and lead has problems such as toxicity, and it is difficult to increase the content.
An object of the present invention is to provide a polyurethane resin-forming composition for a radiation shielding material that is excellent in workability and imparts excellent radiation shielding properties of both neutron rays and γ rays to molded articles.

  The inventors have reached the present invention as a result of intensive studies to solve the above problems. That is, the present invention provides a polyurethane resin-forming composition for radiation shielding material (X) comprising a polyol (A), a polyisocyanate (B) and an inorganic filler (C) having a true specific gravity of 4.0 to 6.0. A polyurethane resin molded product for a radiation shielding material obtained by reaction-curing and molding the (X).

The polyurethane resin-forming composition (X) for radiation shielding material of the present invention has the following effects.
(1) Low viscosity and excellent workability (workability).
(2) A molded product obtained by reaction-curing and molding the composition has excellent shielding properties against radiation, particularly both neutron rays and γ rays.

[Polyol (A)]
The polyol (A) in the present invention contains 2 to 8 or more low molecular polyols (A1) [(hydroxy groups of less than 250 (hereinafter referred to as OH)) equivalents (based on OH value, per OH Molecular weight)], 2-8 or higher polymer polyol (A2) [having an OH equivalent weight of 250 or more], and mixtures of two or more thereof.
Low molecular polyol (A1) includes polyhydric alcohol (A11), and low molecular OH-terminated polymer (A12) [polyether polyol (hereinafter abbreviated as PT polyol), polyester polyol (hereinafter abbreviated as PS polyol) and the like]. It is.

The polyhydric alcohol (A11) includes the following.
Dihydric alcohol [carbon number (hereinafter abbreviated as C) 2-20 or more, for example, C2-12 aliphatic dihydric alcohol [(di) alkylene glycol such as ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), dipropylene glycol (DPG), 1,2-, 2,3-, 1,3- and 1,4-butanediol (BD), 1,6-hexanediol (HD), neopentyl glycol ( NPG) and 3-methylpentanediol (MPD), dodecanediol, etc.]; C6-10 alicyclic dihydric alcohol [1,4-cyclohexanediol, cyclohexanedimethanol, etc.]; C8-20 aromatic ring-containing divalent Alcohol [xylylene glycol, bis (hydroxyethyl) benzene, etc.];
Trihydric to octahydric or higher polyhydric alcohols such as (cyclo) alkane polyols and intramolecular or intermolecular dehydrates thereof [glycerin (GR), trimethylolpropane (TMP), pentaerythritol (PE), sorbitol ( SO) and dipentaerythritol (DPE), 1,2,6-hexanetriol, erythritol, cyclohexanetriol, mannitol, xylitol, sorbitan, diglycerin and other polyglycerins, etc.], sugars and derivatives thereof such as sucrose, glucose, Fructose, mannose, lactose, and glycosides (such as methyl glucoside)];

  Nitrogen-containing polyols (tertiary amino group-containing polyols and quaternary ammonium group-containing polyols): nitrogen-containing diols such as C1-12 aliphatic, alicyclic and aromatic ring-containing primary monoammonium [methylammonium, ethylammonium, 1 -And 2-propylammonium, hexylammonium, 1,3-dimethylbutylammonium, 1-, 2- and 3-aminoheptane, dodecylammonium, cyclopropylammonium, cyclohexylammonium, aniline, benzylammonium and the like] C2-4) compounds [bis (2-hydroxyethyl) compounds, bis (hydroxypropyl) compounds, etc., for example, tertiary nitrogen atom-containing polyols described in US Pat. No. 4,271,217], and their 4 Graded product (Having a C1~4 alkyl group, such as dimethyl, diethyl and di--i- propyl carbonate) quaternizing agent or dialkyl carbonate described in U.S. Patent specification includes. ) Quaternized product], for example, quaternary nitrogen atom-containing polyols described in the above-mentioned U.S. Patent Specification; and trivalent to octavalent or higher nitrogen-containing polyols such as trialkanol (C2-4) amine (triethanolamine Etc.) and C2-12 aliphatic, cycloaliphatic, aromatic and heterocyclic polyamines [eg ethylenediamine, cyclohexanediamine, tolylenediamine, aminoethylpiperazine] polyhydroxyalkyl (C2-4) compounds [poly (2- Hydroxyethyl) compounds, bis (hydroxypropyl) compounds and the like [for example, tetrakis (2-hydroxypropyl) ethylenediamine, pentakis (2-hydroxypropyl) diethylenetriamine], and quaternized compounds similar to those described above.

Low molecular OH-terminated polymers (A12) include PT polyols, PS polyols and PU polyols having an OH equivalent weight of less than 250.
Here, PU polyol refers to a polyol having a urethane bond.
For example, a low-polymerization alkylene oxide (hereinafter abbreviated as AO) ring-opening polymer and a low-mol AO adduct of an active hydrogen atom-containing polyfunctional compound [for example, polyethylene glycol, polypropylene glycol, polytetramethylene glycol (hereinafter referred to as PEG respectively) , PPG, PTMG), etc., bis (hydroxyethoxy) benzene and bisphenol A ethylene oxide 2-4 mol adduct], low condensation polycondensation PS polyol and polyol low mol lactone adduct [polycarboxylic acid and excess (carboxyl) 1 mol per group) condensate with polyhydric alcohol (eg dihydroxyethyl adipate) and 1 mol caprolactone adduct of EG], and low-polymerization PU polyol [hereinafter referred to as polyisocyanate (hereinafter referred to as PI). .)When Retained reaction products of polyhydric alcohols (per isocyanate group 1 mol) (e.g. the reaction product of TDI1 moles and EG2 mol described later) and the like.

  AO includes C2-12 or more (preferably C2-4) AO such as ethylene oxide, 1,2-propylene oxide, 1,2-, 2,3- and 1,3-butylene oxide, tetrahydrofuran and 3 -Methyl-tetrahydrofuran (hereinafter abbreviated as EO, PO, BO, THF, and MTHF), 1,3-propylene oxide, isoBO, C5-12 α-olefin oxide, substituted AO such as styrene oxide and epihalohydrin (epichlorohydrin, etc.) ), And combinations of two or more of these (random addition and / or block addition).

  The polymer polyol (A2) usually has an OH equivalent of 250 to 3,000 or more. The polyol usually has a number average molecular weight (hereinafter abbreviated as Mn. Measurement is based on gel permeation chromatography (GPC) method) of 500 to 3,000 or more, preferably 500 to 1,000; It preferably has a weight average molecular weight of 500 to 3,000, more preferably 700 to 2,500 (hereinafter abbreviated as Mw. The measurement is based on the GPC method.) Examples thereof include OH-terminated polymers [PT polyol, PS Polyol, polyamide (hereinafter abbreviated as PD), PU polyol, vinyl polymer (hereinafter abbreviated as VP) and polymer polyol (hereinafter abbreviated as P / P)], and a mixture of two or more thereof. PT polyol has at least 2 (2-8 or more) active hydrogen atoms, ring-opening polymer of AO PT polyol having a structure in which one or more kinds of AO are added to an initiator (AO adduct), and two or more of them (same or different) coupled with a coupling agent A polyol is included.

  Initiators for AO addition include, for example, polyhydric alcohols (described above), hydroxylamines, aminocarboxylic acids and hydroxycarboxylic acids; polyhydric phenols; and polycarboxylic acids (described below).

  Hydroxylamine includes C2-10 (di) alkanolamines, cycloalkanolamines and alkylalkanolamines such as ethanolamine, propanolamine, butanolamine, hexanolamine, diethanolamine, di-n- and i-propanolamine, methyl -3,5,5-trimethylcyclohexanolamine, methylethanolamine and ethylethanolamine are included. Preference is given to ethanolamine.

Aminocarboxylic acids include those having C2-12, such as amino acids [glycine, alanine, valine, (iso) leucine, phenylalanine, etc.], ω-aminoalkanoic acids (for example, ω-aminocapron, ω-aminoenanthate, ω-aminocapryl). , Ω-aminopergon, ω-aminocaprin, 11-aminoundecane and 12-aminododecanoic acid), and aromatic aminocarboxylic acids such as o-, m- and p-aminobenzoic acid.
Hydroxycarboxylic acids include those corresponding to the above aminocarboxylic acids (NH substituted with O) (for example, ω-hydroxycaproic acid, salicylic acid, p- and m-hydroxybenzoic acid), glycolic acid, glyceric acid, Tartronic acid, malic acid, tartaric acid and benzylic acid are included. Preference is given to 12-aminododecanoic acid.

  The polyhydric phenol includes C6-18 dihydric phenol such as monocyclic dihydric phenol (hydroquinone, catechol, resorcinol, urushiol, etc.), bisphenol (bisphenol A, F, C, B, AD and S, dihydroxybiphenyl, 4,4′-dihydroxydiphenyl-2,2-butane, etc.), and condensed polycyclic dihydric phenols [dihydroxynaphthalene (eg, 1,5-dihydroxynaphthalene), binaphthol, etc.]; and trivalent to octavalent or higher Polyhydric phenols, such as monocyclic polyhydric phenols (pyrogallol, phloroglucinol, and mono- or dihydric phenols (phenol, cresol, xylenol, resorcinol, etc.) aldehydes or ketones (formaldehyde, glutaraldehyde, glyoxal) Acetone) Teichijimigobutsu (such as phenol or cresol novolak resins, intermediates resol, polyphenols obtained by condensation reaction of phenol with glyoxal or glutaraldehyde, and a polyphenol) obtained by condensation reaction of resorcin and acetone.

  The addition of AO to the initiator can be carried out in the usual manner, and is carried out at atmospheric pressure in the presence of no catalyst or catalyst (alkali catalyst, ammonium catalyst, acidic catalyst, etc.) (especially in the latter stage of AO addition). Alternatively, it is performed in one step or multiple steps under pressure. Two or more types of AO may be random addition, block addition, or a combination of both (for example, random addition followed by block addition). Coupling agents for AO adducts include polyhalides such as C1-6 alkane polyhalides (eg C1-4 alkylene dihalides: methylene dichloride, 1,2-dibromoethane etc.); epihalohydrins (eg epichlorohydrin etc.); and polyepoxides Is included.

  Examples of OH-terminated PT polyols include PT diols such as polyalkylene glycol (hereinafter abbreviated as PAG) [eg PEG, PPG and PTMG, poly-3-methyltetramethylene ether glycol], copolymer polyoxyalkylene diol [EO / PO copolymer diol, THF / EO copolymer diol, THF / MTHF copolymer diol, etc. (weight ratio, for example, 1/9 to 9/1)], aromatic ring-containing polyoxyalkylene diol [polyoxyalkylene bisphenol A (bisphenol) EO and / or PO adducts of A)]; and trifunctional or higher functional PT polyols such as polyoxypropylene triol (eg, PO adduct of GR); and one or more of these coupled with methylene dichloride included.

  OH-terminated PS polyols include condensed PS polyols, polylactone (hereinafter abbreviated as PL) polyols, castor oil polyols [castor oil (ricinoleic acid triglycerides) and modified polyols thereof], and polycarbonate polyols. The condensed PS polyol is a polycondensation of a polyol and a polycarboxylic acid (refers to an acid or an ester-forming derivative thereof; the same shall apply hereinafter) (and a hydroxycarboxylic acid if necessary) or a reaction of the polyol with a polycarboxylic acid anhydride and AO. PL polyol is obtained by ring-opening addition of a lactone using a polyol as an initiator (or polycondensation of polyol and hydroxycarboxylic acid), a polyol modified product of castor oil is obtained by transesterification of castor oil and polyol, and polycarbonate. Polyol is a ring-opening addition / polycondensation of an alkylene carbonate using a polyol as an initiator, a polycondensation (transesterification) of a polyol and a diphenyl or dialkyl carbonate, or a polyol or a dihydric phenol (the above: bisphenol A, etc.) The Sugen reduction, can be produced.

  The polyol used for the production of the PS polyol usually has an OH equivalent (Mn per OH) of 1,000 or less, preferably 30 to 500. Examples thereof include the above polyhydric alcohols [diols (eg, EG, 1,4-BD, NPG, HD and DEG) and trivalent or higher polyols (GR, TMP, PE, etc.)], the above PT polyols (PEG, PPG, PTMG, etc.), and mixtures of two or more thereof. Preferred for the production of the condensed PS polyol is a combination of a diol and a small proportion (for example, 10 equivalent% or less) of a trivalent or higher polyol.

  The polycarboxylic acid includes dicarboxylic acids and trivalent to tetravalent or higher polycarboxylic acids. Examples thereof include C2-30 or more (preferably C2-12) saturated and unsaturated aliphatic polycarboxylic acids such as C2-15 dicarboxylic acids (eg oxalic acid, succinic acid, malonic acid, adipic acid , Suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic acid, fumaric acid and itaconic acid), C6-20 tricarboxylic acids (eg tricarbaryl and hexanetricarboxylic acid)]; C8-15 aromatic polycarboxylic acids, For example dicarboxylic acids (eg terephthalic acid, isophthalic acid and phthalic acid), tri- and tetra-carboxylic acids (eg trimellitic acid and pyromellitic acid); C6-40 alicyclic polycarboxylic acids (eg dimer acid); and Sulfo group-containing polycarboxylic acid [by introducing a sulfo group into the polycarboxylic acid Such as sulfosuccinic acid, sulfomalonic acid, sulfoglutaric acid, sulfoadipic acid and sulfoisophthalic acid, and their salts (alkali metal, alkaline earth metal and group IIB metal salts, ammonium salts, ammonium salts, and quaternary ammonium Salts, etc.)]; as well as carboxy-terminated polymers.

  Carboxy-terminated polymers include PT polycarboxylic acids such as carboxymethyl ethers of polyols [polyhydric alcohols, PT polyols etc. above] (obtained by reacting monochloroacetic acid in the presence of alkali); and PD, PS and / Or PU polycarboxylic acid, for example, polylactam polycarboxylic acid obtained by ring-opening polymerization of lactam or lactone (described above) using the above polycarboxylic acid as an initiator, PL polycarboxylic acid, two or more molecules of the above polycarboxylic acids A condensed PS polycarboxylic acid and a condensed PD polycarboxylic acid obtained by coupling (esterification or amidation) with a polyol (previously) or polyammonium or polyisocyanate (PI, hereinafter), and the above polycarboxylic acids and polyol Anti-PI Include PU polycarboxylic acids comprising (urethanization and esterification or amidation) is allowed.

  Lactams include those of C4-15 (preferably C6-12) such as caprolactam, enantolactam, laurolactam and undecanolactam; lactones include, for example, ε-caprolactone, γ-butyrolactone, γ-valerolactone. .

  Ester forming derivatives include acid anhydrides, lower alkyl (C1-4) esters and acid halides such as succinic, maleic, itacone and phthalic anhydride, dimethyl terephthalate, and malonyl dichloride. Preferred for the production of the condensed PS polyol is a combination of a dicarboxylic acid and a small proportion (for example, 10 equivalent% or less) of a trivalent to tetravalent or higher polycarboxylic acid. Lactones and hydroxycarboxylic acids include those listed above. Alkylene carbonates include those having a C2-6 alkylene group, such as ethylene and propylene carbonate. Dialkyl carbonates include those having a C1-4 alkyl group, such as dimethyl, diethyl and di-i-propyl carbonate.

  Specific examples of OH-terminated PS polyols include polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polyneopentylene adipate, polyethylene / propylene adipate, polyethylene / butylene adipate, polybutylene / hexamethylene adipate, polydiethylene adipate, poly (Polytetramethylene ether) adipate, polyethylene azelate, polyethylene sebacate, polybutylene azelate, polybutylene sebacate, polycaprolactone diol and polyhexamethylene carbonate diol.

  The OH-terminated PD includes poly (ester) amide polyols obtained by polycondensation of polycarboxylic acids (above) with hydroxylamine (above) or polyol (above) and polyamine (PA) (above).

  The OH-terminated PU includes an OH-terminated urethane prepolymer obtained by modifying a polyol with PI. The polyol includes the above-mentioned polyhydric alcohol, polymer polyol (the above-mentioned OH-terminated PT and PS, and OH-terminated VP and P / P described later), and combinations of two or more thereof. Among the polyols, preferred are high-molecular polyols (especially OH-terminated PS and especially PT) and combinations thereof with low-molecular polyols (especially polyhydric alcohols). The amount of the low molecular polyol to be used in combination can be appropriately changed according to the required performance, but is generally 0.01 to 0.5 equivalent, more preferably 0.02 to 0.00 with respect to 1 equivalent of the polymer polyol. 4 equivalents, particularly 0.1 to 0.2 equivalents are preferred. In the production of the OH-terminated urethane prepolymer, the equivalent ratio of polyol to PI (OH / NCO ratio) is usually 1.1 / 1 to 10/1, preferably 1.4 / 1 to 4/1, particularly 1.4. / 1 to 2/1. The polyol and PI may be reacted in a single stage or in multiple stages (for example, after reacting a part of the polyol or PI, the remainder is reacted).

  OH-terminated VPs include polybutadiene-based polyols such as OH-terminated butadiene homopolymers and copolymers (styrene-butadiene copolymers, acrylonitrile-butadiene copolymers, etc.) [those having 1,2-vinyl structures, 1,4-trans structures. Having 1,4-cis structure, and having two or more of these (molar ratio of 1,2-vinyl / 1,4-trans / 1,4-cis 100-0 / 100-0 / 100 to 0, preferably 10 to 30/50 to 70/10 to 30], and hydrogenated products thereof (hydrogenation rate: eg 20 to 100%); acrylic polyols such as acrylic copolymers [alkyl (C1 -20) (Meth) acrylate, or a copolymer of these and other monomers (styrene, acrylic acid, etc.)] Obtained by introducing a hydroxyl group [introducing hydroxyl groups hydroxyethyl (meth) according acrylate primarily]; included and partially saponified ethylene / vinyl acetate copolymer.

  P / P is obtained by in situ polymerization of an ethylenically unsaturated monomer in a polyol (previously OH-terminated PT and / or PS, or a mixture thereof with the polyhydric alcohol). Ethylenically unsaturated monomers include acrylic monomers such as (meth) acrylonitrile and alkyl (C1-20 or higher) (meth) acrylate (such as methyl methacrylate); hydrocarbon (hereinafter abbreviated as HC) monomers such as aromatic Unsaturated HC (such as styrene) and aliphatic unsaturated HC (C2-20 or higher alkenes, alkadienes, such as α-olefins and butadiene); and combinations of two or more thereof (for example, combined use of acrylonitrile / styrene) (Weight ratio 100/0 to 80/20)]. P / P has a polymer content of, for example, 5 to 80% or more, preferably 30 to 70%. Among the above polymer polyols, PT polyol and PS polyol are preferable.

Among the above polyols (A), castor oil polyol is preferable from the viewpoints of workability and neutron shielding properties.
In addition, a polyol (A) may be used individually by 1 type, or may use 2 or more types together.
When (A) contains castor oil polyol, castor oil polyol is preferably 30% or more, more preferably 50% or more, based on the weight of (A), from the viewpoint of workability and neutron ray shielding. Particularly preferably, it is 70% or more, most preferably 100%.

[Polyisocyanate (B)]
In the polyisocyanate (B) in the present invention, the following polyisocyanate (PI) having 2 to 6 or more (preferably 2 to 3, particularly 2) isocyanate groups, and two or more of these A mixture is included.
(1) C (excluding carbon in the NCO group, the same shall apply hereinafter) 2 to 18 aliphatic PI:
Diisocyanates (hereinafter abbreviated as DI), such as ethylene DI, tetramethylene DI, hexamethylene DI (HDI), heptamethylene DI, octamethylene DI, decamethylene DI, dodecamethylene DI, 2,2,4- and / or 2,4 , 4-trimethylhexamethylene DI, lysine DI, 2,6-diisocyanatomethylcaproate, 2,6-diisocyanatoethylcaproate, bis (2-isocyanatoethyl) fumarate and bis (2-isocyanatoethyl) Carbonate;
Trifunctional or higher functional PI (such as triisocyanate), such as 1,6,11 1-undecane triisocyanate, 1,8-diisocyanate-4-isocyanate methyloctane, 1,3,6-hexamethylene triisocyanate and lysine ester triisocyanate (Phosgenates of reaction products of lysine and alkanol ammonium, 2-isocyanatoethyl-2,6-diisocyanatohexanoate, 2- and / or 3-isocyanatopropyl-2,6-diisocyanatohexa Noate);

(2) C4-15 alicyclic PI: DI, such as isophorone DI (IPDI), dicyclohexylmethane-4,4'-DI (hydrogenated MDI), cyclohexylene DI, methylcyclohexylene DI, bis (2-isocyanate) Natoethyl) -4-cyclohexylene-1,2-dicarboxylate and 2,5- and / or 2,6-norbornane DI; tri- or higher functional PI (such as triisocyanate), such as bicycloheptane triisocyanate;
(3) C8-15 araliphatic PI: m- and / or p-xylylene DI (XDI), diethylbenzene DI and α, α, α ′, α′-tetramethylxylylene DI (TMXDI);
(4) C6-20 aromatic PI: DI, for example 1,3- and / or 1,4-phenylene DI, 2,4- and / or 2,6-tolylene DI (TDI), 4, 4′- And / or 2,4′-diphenylmethane DI (MDI), m- and p-isocyanatophenylsulfonyl isocyanate, 4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4,4′-diisocyanato Biphenyl, 3,3′-dimethyl-4,4′-diisocyanatodiphenylmethane and 1,5-naphthylene DI; trifunctional or higher functional PI (such as triisocyanate), such as crude TDI, crude MDI (polymethylene polyphenylene polyisocyanate) ;

(5) Modified form of PI:
Modified products of the above PI, such as modified products having carbodiimide, urethane, urea, isocyanurate, uretoimine, allophanate, biuret, oxazolidone and / or uretdione groups), such as urethane modified products such as MDI, TDI, HDI, IPDI NCO-terminated urethane prepolymer obtained by reacting with excess PI), biuret modified product, isocyanurate modified product, trihydrocarbyl phosphate modified product, and mixtures thereof. The polyol used for urethane modification includes the polyhydric alcohol, PT polyol and / or PS polyol. Preferred are polyols having an OH equivalent weight of 500 or less, particularly 30 to 200, such as glycols (EG, PG, DEG, DPG, etc.), triols (TMP, GR, etc.), tetrafunctional or higher functional polyols (PE, SO, etc.). And their AO (EO and / or PO) (1-40 mol) adducts, especially glycols and triols. The equivalent ratio of PI and polyol (NCO / OH ratio) in urethane modification is usually 1.1 / 1 to 10/1, preferably 1.4 / 1 to 4/1, particularly 1.4 / 1 to 2/1. It is. The content of free isocyanate groups in the modified PI is usually 8 to 33%, preferably 10 to 30%, particularly preferably 12 to 29%.

Of the polyisocyanates (B), aliphatic PI and alicyclic PI are preferable from the viewpoints of neutron ray shielding and workability.
In addition, polyisocyanate (B) may be used individually by 1 type, or may use 2 or more types together.

[Inorganic filler (C) having a true specific gravity of 4.0 to 6.0]
Examples of the inorganic filler (C) having a true specific gravity of 4.0 to 6.0 in the present invention include, for example, a barium compound (C1), a zinc compound (C2), a titanium compound (C3), a manganese compound (C4), and an iron compound ( C5).
(C1) is barium sulfate, barium carbonate, barium chloride, barium iodide, barium oxide, etc .; (C2) is zinc chloride, zinc carbonate, etc .; (C3) is titanium oxide, etc .; (C4) Is manganese oxide, manganese dioxide, etc .; (C5) includes iron oxide and the like.
Among the above (C), from the viewpoint of workability and radiation shielding properties, (C1) is preferable, and barium sulfate is more preferable.
When the true specific gravity is less than 4.0, the γ-ray shielding property of a molded product obtained by reaction-curing the composition tends to be reduced. When the true specific gravity exceeds 6.0, the neutron ray shielding property is lowered. Tend.
The preferred properties for use of (C) are powdery and the particle size is not particularly limited, but the volume average particle size of (C) is preferably 0.5 to 500 μm from the viewpoint of uniformity and dispersibility. More preferably, it is 1-50 micrometers, Most preferably, it is 10-30 micrometers.
In addition, said (C) may be used individually by 1 type, or may use 2 or more types together.

[Polyurethane resin-forming composition for radiation shielding material (X)]
The polyurethane resin-forming composition (X) for a radiation shielding material of the present invention contains the polyol (A), the polyisocyanate (B), and an inorganic filler (C) having a true specific gravity of 4.0 to 6.0. Become.

  The content based on the total weight of (A), (B) and (C) is preferably 10 to 28%, more preferably 13 to 25%, and particularly preferably 14 to from the viewpoint of workability. 20%; (B) from the same viewpoint, preferably 10 to 28%, more preferably 13 to 25%, particularly preferably 14 to 20%; (C) is from the viewpoint of radiation shielding properties and workability. Preferably it is 61-75%, More preferably, it is 63-72%, Most preferably, it is 66-71%.

  The polyurethane resin-forming composition (X) for radiation shielding material of the present invention may further contain an inorganic filler (D) other than (C) described later.

[Inorganic filler (D)]
Examples of the inorganic filler (D) include known inorganic fillers other than the inorganic filler (C), and boron compounds (D1) and gadolinium compounds (D2) are preferable from the viewpoint of neutron beam shielding properties.
Note that (D) is capable of absorbing thermal neutrons generated by slowing down fast neutrons, and therefore has a large neutron absorption cross section and does not emit secondary γ rays or contains low energy even when emitted. It is preferable.

Examples of the boron compound (D1) include boron carbide, colemanite, boron oxide, borax and the like, and these may be used alone or in combination. Among (D1), boron oxide is preferable from the viewpoint of neutron ray shielding and availability.
Examples of the gadolinium compound (D2) include gadolinium oxide and gadolinium sulfate, and these may be used alone or in combination. Of (D2), gadolinium oxide is preferable from the viewpoint of neutron ray shielding and easy availability.

  In addition, the volume average particle diameter of (D) is preferably 0.5 to 500 μm, more preferably 1 to 100 μm, and particularly preferably 5 to 50 μm from the viewpoints of workability and neutron beam shielding properties.

  When the inorganic filler (D) is contained, the content based on the total weight of (A), (B), (C) and (D) is preferably (A) from the viewpoint of workability (constructability). 10 to 25%, more preferably 13 to 22%, particularly preferably 15 to 20%; from the same viewpoint, (B) is preferably 5 to 15%, more preferably 6 to 12%, particularly preferably 7 to 10%. %; (C) is preferably 60 to 75%, more preferably 65 to 72%, particularly preferably 68 to 70% from the viewpoint of γ-ray shielding and workability; and (D) is neutron shielding. From the viewpoint of workability, it is preferably 1 to 10%, more preferably 1 to 5%, and particularly preferably 1 to 3%.

  The mixing ratio [NCO / OH equivalent ratio] of the polyol (A) and the polyisocyanate (B) is preferably 1.3 / 1 to 0.8 to 1, more preferably 1.2 / 1 to 0.9 / 1. The curing catalyst described later is preferably mixed at a ratio of 0.001 to 0.1% by weight with respect to the total weight of the polyol (A) and the polyisocyanate (B).

Examples of the curing catalyst include bismuth nitrate, bismuth bromide, bismuth iodide, bismuth sulfide, dibutyl bismuth dilaurate, dioctyl bismuth dilaurate, 2-ethylhexanoic acid bismuth salt, naphthenic acid bismuth salt, and isodecanoic acid bismuth salt. Bismuth neodecanoate, bismuth laurate, bismuth maleate, bismuth stearate, bismuth oleate, bismuth linoleate, bismuth acetate, bismuth bisneodecanoate, bismuth disalicylate, digallic acid Examples thereof include organic bismuth compounds such as bismuth salts of organic acids such as bismuth salts.
Of the above curing catalysts, from the viewpoint of reactivity, preferred are organic acid bismuth salts, more preferred are 2-ethylhexanoic acid bismuth salt, neodecanoic acid bismuth salt, naphthenic acid bismuth salt, isodecanoic acid bismuth salt, and particularly preferred are It is bismuth 2-ethylhexanoate.

  In the polyurethane-forming resin composition for a radiation shielding material of the present invention, in the range not inhibiting the effects of the present invention, if necessary, in addition to the above (A), (B), (C), (D) and the curing catalyst, What is used for manufacture of a normal polyurethane resin may contain all, and a dehydrating agent, an antifoamer, etc. are mentioned specifically ,.

  The polyurethane resin-forming composition (X) for radiation shielding material of the present invention comprises, for example, a polyol (A), a polyisocyanate (B), an inorganic filler (C), and if necessary an inorganic filler (D), a curing catalyst, and an antifoaming agent. An agent and a dehydrating agent are simultaneously placed in a container such as a pail can, and preferably obtained by defoaming and mixing using a vacuum hard mixer at a stirring speed of 1 to 3 m / s for 15 to 30 minutes.

  The viscosity of the polyurethane resin-forming composition (X) in the present invention is a measured value at 30 ° C. after 5 minutes of the composition obtained by mixing for 20 minutes. The viscosity is preferably 100 to 50,000 mPa · s, more preferably 150 to 20,000 mPa · s, and particularly preferably 200 to 6,000 mPa · s from the viewpoints of radiation shielding properties and workability.

[Polyurethane resin molded products for radiation shielding materials]
The polyurethane resin molded product for a radiation shielding material of the present invention is formed by reaction-curing the polyurethane resin-forming composition (X) for a radiation shielding material.

The hydrogen atom concentration of the polyurethane resin molded product for radiation shielding material is preferably 4.0 × 10 ²² pieces / cm ^{3 to} 7.5 × 10 ²² pieces / cm from the viewpoint of neutron ray shielding property and γ ray shielding property. ³ , more preferably 4.5 × 10 ²² pieces / cm ^{3 to} 6.5 × 10 ²² pieces / cm ³ , particularly preferably 5.0 × 10 ²² pieces / cm ^{3 to} 6.0 × 10 ²² pieces / cm 3 ^{There are three} .

In the present invention, the hydrogen atom concentration (unit: piece / cm ³ ) of the molded product can be calculated by the following formula (1).

[Hydrogen _{concentration] = m H × N A ×} ρ / m (1)

However,
m _H : Mass of all hydrogen atoms in the molded product (weight)
N _A : Avogadro's number (6.002 × 10 ²³ )
ρ: Density of molded product (unit: g / cm ³ , 25 ° C.)
m: mass (weight) of all atoms in the molded product

_{M H} is the total mass of all hydrogen atoms of each component of the composition, m is the total mass of all atoms of each component of the composition, and ρ is the density and weight of each component of the composition. It can be calculated from the ratio.
Moreover, the hydrogen atom concentration in the below-mentioned Example was computed based on the said Formula (1) from the component of the said composition (X), its weight ratio, and the density of a molded article.

In order to make the hydrogen atom concentration of the molded product within the above-mentioned range, the types and amounts of the polyol (A), the polyisocyanate (B) and the inorganic filler (C), as well as those described later (C) are added if necessary. This is possible by appropriately adjusting the type and amount of the inorganic filler (D).
That is, (A), (B), (C) and (D) are each preferably selected, and the amounts of (A), (B), (C) and (D) will be described later. For example, the hydrogen atom concentration of the molded product can be set within a preferable range.

Although it does not specifically limit as a manufacturing method of the said polyurethane resin molded product, For example, the main ingredient component containing a polyol (A) and the hardening | curing agent component containing a polyisocyanate (B) are mixed and mixed. There is a method of obtaining a liquid, that is, a composition (X), casting, and heating and heating (for example, 100 ° C.) as necessary to obtain a reaction and curing.
In the production method, the inorganic filler (C) and the inorganic filler (D) to be contained as necessary are preferably contained in the main component and the curing agent component, respectively, and the curing catalyst is contained in the main component. preferable.

The cast mixed liquid is preferably cured at 70 to 130 ° C., more preferably 80 to 120 ° C., and preferably 0.5 to 10 hours in a curing furnace to obtain a molded product.
As the material of the mold, metal (aluminum, stainless steel, etc.) or plastic (polypropylene, polycarbonate, etc.) is usually used.

  Further, in the field construction, for example, a premix of the main component and the curing agent component is sprayed and then cured by reaction to obtain a polyurethane resin molded product for a radiation shielding material.

[Radiation shielding material]
The radiation shielding material of the present invention is obtained by processing the polyurethane resin molded product for the radiation shielding material. That is, a radiation shielding material can be obtained by subjecting the molded product to processing such as cutting, cutting, cutting, punching, and hot pressing as necessary. Alternatively, the polyurethane resin-forming composition for radiation shielding material (X) may be cast into a mold or the like and reacted and cured to obtain a polyurethane resin molded product, which may be used as a radiation shielding material.

  The polyurethane resin moldable composition (X) for radiation shielding material of the present invention has excellent workability (workability) due to its low viscosity, and the molded product of the composition (X) is composed of radiation, particularly neutron rays and γ rays. Since it has excellent shielding properties, it can be used widely as a radiation shielding material for field construction, and is particularly useful.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In the following, parts represent parts by weight.

The composition and symbols of the raw materials used in Examples and Comparative Examples are as follows.
Polyol (A-1):
Ricinoleic acid triglyceride, polyester polyol with an OH equivalent of 333.3,
Product name "ELA-DR", Toyokuni Oil Co., Ltd.],
Polyol (A-2):
PO Adduct of Glycerin, Polyether Polyol with an OH Equivalent of 83.3 [Trade Name “Sanix GP250”, Sanyo Chemical Industries, Ltd.]
Polyol (A-3):
PO Adduct of Glycerin, Polyether Polyol with OH Equivalent 133.3 [Trade Name “Sanix GP400”, Sanyo Chemical Industries, Ltd.]

Polyisocyanate (B-1):
Isophorone diisocyanate, [trade name “VESTANAT IPDI”,
Evonik Degussa Japan Co., Ltd.]
Polyisocyanate (B-2):
Hexane diisocyanate (HDI), [trade name “Duranate 50M”
Asahi Kasei Chemicals Corporation]
Polyisocyanate (B-3):
Polymeric MDI, [trade name "Luprinate M20S",
BASF Japan Co., Ltd.]

Inorganic filler (C-1): precipitated barium sulfate [trade name “BMH-100”,
Volume average particle diameter 12 μm, true specific gravity 4.5, manufactured by Sakai Chemical Industry Co., Ltd.]
Inorganic filler (C-2): fertile barium sulfate [trade name “BA”,
Volume average particle size 8 μm, true specific gravity 4.5, manufactured by Sakai Chemical Industry Co., Ltd.]
Inorganic filler (C-3): Zinc oxide [trade name “Zinc oxide 2 types”,
Volume average particle size 0.6 μm, true specific gravity 5.6, manufactured by Nippon Chemical Industry Co., Ltd.]
Inorganic filler (C-4): Titanium oxide [Brand name "Titanium oxide"
Volume average particle diameter 0.3 μm, true specific gravity 4.3, manufactured by Teika Co., Ltd.]
Inorganic filler (ratio C-1): calcium carbonate [trade name “Whiteon SB Red”,
Volume average particle diameter 1.8 μm, true specific gravity 2.7, manufactured by Shiraishi Calcium Co., Ltd.]
Inorganic filler (ratio C-2): iron powder [trade name “KIP K-100T”,
Volume average particle size 100 μm, true specific gravity 7.8, manufactured by JFE Steel Corporation]

Inorganic filler (D-1):
Boron oxide, “trade name“ boron oxide ”, volume average particle size 250 μm,
True specific gravity 2.5, manufactured by Nippon Electric Works Co., Ltd. "
Inorganic filler (D-2):
Gadolinium oxide [trade name “gadolinium oxide”, volume average particle size 3.5 μm,
True specific gravity 7.4, manufactured by Japan Yttrium Co., Ltd.]

Antifoaming agent: Mixture of dimethylpolysiloxane and silicon dioxide [trade name “SH5500”, manufactured by Toray Dow Corning Co., Ltd.]
Dehydrating agent: Synthetic zeolite [Product name "Molecular sieve 3AB powder" manufactured by Union Showa Co., Ltd.]
Curing catalyst: Bismuth 2-ethylhexanoate [Brand name "Neostan U-600", Nitto Kasei Co., Ltd.]

Examples 1 to 10, Comparative Examples 1 to 3 (Comparative Example 3 describes a polyethylene block)
In accordance with the resin composition (parts) shown in Table 1, the polyol (A) is charged with an inorganic filler (C), an inorganic filler (D), then an antifoaming agent, a dehydrating agent, and a curing catalyst in a hard mixer and subjected to vacuum conditions for 15 minutes. And mixed with polyisocyanate (B) and stirred and mixed for 20 minutes using a hard mixer under vacuum conditions to obtain a polyurethane resin-forming composition (X) for a radiation shielding material. . The composition (X) was poured into a mold (length 35 cm × width 35 cm × height 15 cm).

The above steps and the production of the molded product were performed by the following method.
The mixing ratio [NCO / OH equivalent ratio] of the polyol (A) and the polyisocyanate (B) was 1.0 / 1.0.
The liquid [composition (X)] mixed under vacuum conditions using a hard mixer was poured into a metal mold. The received mixed liquid was cured at 110 ° C. for 10 hours in a curing furnace to obtain a molded product.

  The viscosity, the density of the molded product, the workability (workability), and the radiation shielding property of the polyurethane resin-forming composition (X) obtained as described above were measured by the following evaluation methods, and the evaluation results are shown in Table 1.

<Viscosity>
About composition (X) which finished stirring and mixing, the viscosity (30 degreeC) after 5 minutes was measured according to JISK7117-1 with a B-type viscosity meter. In addition, the measurement used B-type viscosity measuring apparatus [model number TBV-10] Toki Sangyo Co., Ltd.

<Workability (workability)>
The ease of handling and ease of spraying during work were evaluated according to the following criteria based on the above <viscosity>.
[Judgment criteria]
◎: Viscosity is 6,000 mPa · s or less ○: Viscosity is more than 6,000 mPa · s, 50,000 mPa · s or less ×: Viscosity is more than 50,000 mPa · s

<Density>
A rectangular parallelepiped shaped product was cut into a length of 35 mm, a width of 35 mm, and a thickness of 50 mm to obtain a measurement sample, which was measured by an underwater substitution method in accordance with JIS K7112.
The specific gravity measuring device [model number AUX320] manufactured by Shimadzu Corporation was used for the measurement.

<Radiation shielding property, γ-ray shielding rate>
A rectangular parallelepiped shaped product was cut into a length of 200 mm, a width of 200 mm, and a thickness of 100 mm to obtain a measurement sample. A radiation source, a sample, a lead collimator (φ15 mm × width 100 mm), and a measuring device were installed on the test bench in order from the left side. The sample was installed with respect to the radiation source so as to have a thickness of 100 mm. With and without the sample, γ rays from a radiation source were irradiated and the dose was measured with a measuring instrument. The measurement in each case was performed 10 times. From each average value, the gamma ray shielding rate (%) was calculated by the following formula. The dose when there was no sample was 21.5 μSv / h.

γ-ray shielding rate (%) = 100− (dose with sample) × 100 / (dose without sample)

[Measurement condition]
Radiation source: Cesium 137 radiation source 10MBq
Japan Isotope Association Irradiation Dose Rate Standard Gamma Ray Source CS454CE
Measuring instrument: NaI scintillation survey meter Aroka TCS-171B

<Radiation shielding properties, neutron shielding rate>
A rectangular parallelepiped shaped product was cut into a length of 200 mm, a width of 200 mm, and a thickness of 100 mm to obtain a measurement sample. A radiation source, a sample, a lead collimator (φ15 mm × width 100 mm), and a measuring device were installed on the test bench in order from the left side. The sample was installed with respect to the radiation source so as to have a thickness of 100 mm. The neutron beam from the radiation source was irradiated with and without the sample, and the dose was measured with a measuring instrument. The measurement in each case was performed 10 times. From each average value, the neutron ray shielding rate (%) was calculated by the following formula. The dose when there was no sample was 12.7 μSv / h.

Neutron beam shielding rate (%) = 100− (dose with sample) × 100 / (dose without sample)

[Measurement condition]
Radiation source: Californium 252 (Cf-252) neutron radiation source 3.7MBq
Eckert & Ziegler N-252 S.E. N CA406S102S
Measuring instrument: Aloka neutron survey meter TPS-451BS N. 46R928

  From Table 1, the urethane resin-forming composition for radiation shielding material (X) of the present invention has a low viscosity and excellent workability (workability) compared to the comparative one, and the radiation shielding material obtained by reaction-curing the composition. It can be seen that the polyurethane resin molded article for the material is excellent in shielding properties against radiation, particularly both γ rays and neutron rays.

  The polyurethane resin-forming composition for a radiation shielding material of the present invention is excellent in workability (workability) and can impart radiation shielding properties to a molded product, and thus is extremely useful as a radiation shielding material. Furthermore, the radiation shielding material obtained by processing a molded product can be widely used for a collimator, a radiation shielding wall requiring a complicated shape, and the like.

Claims (11)

  A polyurethane resin-forming composition for radiation shielding material (X) comprising a polyol (A), a polyisocyanate (B), and an inorganic filler (C) having a true specific gravity of 4.0 to 6.0.   The polyurethane resin-forming composition according to claim 1, wherein the castor oil polyol is 50% or more based on the weight of the polyol (A).   The polyurethane resin-forming composition according to claim 1 or 2, wherein the polyisocyanate (B) is an aliphatic and / or alicyclic polyisocyanate.   The polyurethane resin-forming composition according to any one of claims 1 to 3, wherein the inorganic filler (C) is barium sulfate.   The polyurethane resin-forming composition according to any one of claims 1 to 4, wherein the content of (C) based on the total weight of the polyol (A), polyisocyanate (B) and inorganic filler (C) is 61 to 75%. .   Furthermore, the polyurethane resin-forming composition according to any one of claims 1 to 5, comprising an inorganic filler (D) other than (C).   The polyurethane resin-forming composition according to claim 6, wherein the inorganic filler (D) is at least one selected from the group consisting of a boron compound and a gadolinium compound.   A polyurethane resin molded product for a radiation shielding material, which is obtained by reaction-curing and molding the polyurethane resin-forming composition (X) according to any one of claims 1 to 7. The polyurethane resin molded article according to claim 8, wherein the hydrogen atom concentration is 4.0 × 10 ²² atoms / cm ^{3 to} 7.5 × 10 ²² atoms / cm ³ . The polyurethane resin molded article according to claim 8 or 9, wherein the density is 2.1 to 2.5 g / cm ³ .   A radiation shielding material obtained by processing the molded product according to claim 10.