JPH0262563B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a methacrylic resin composition containing samarium and having excellent optical and mechanical properties, and a method for producing the same. Methacrylic resin is used in a variety of fields due to its excellent transparency, weather resistance, and mechanical properties. However, since methacrylic resin does not have radiation shielding ability, it cannot be used for these purposes. Ta. Therefore, in recent years, radiation shielding materials containing lead in methacrylic resin have been developed (Special Publications Publication No.
No. 2360, Japanese Patent Publication No. 53-9994, No. 53-9995, No. 53
-9996, and 53-63310, etc.). However, although the lead-containing radiation shielding materials described above effectively shield radiation from electromagnetic waves such as X-rays and γ-rays and charged particles such as α-rays and β-rays, they do not shield against neutron radiation. Not enough. On the other hand, it is also known to add a boron compound to polyethylene or methacrylic resin as a polymeric material for shielding neutron beams (Japanese Unexamined Patent Publication No. 144597-1987).
issue). However, although this method also has a large neutron beam absorption capacity, the helium and lithium produced in the neutron absorption reaction have almost no neutron absorption capacity, so their capacity tends to decrease as the amount of neutron absorption increases. However, the optical and mechanical properties have not yet reached a satisfactory level. In addition to the boron compounds mentioned above, samarium, a rare earth element with an atomic number of 64, is known as a substance that absorbs neutron beams, and has an even greater ability to absorb thermal neutron beams than boron. However, since samarium is a metallic solid, it has poor compatibility with methacrylic polymers, and methacrylic resins with excellent optical and mechanical properties have not yet been produced. The inventor of the present invention has arrived at the present invention as a result of various studies in view of the above circumstances. A methacrylic resin composition containing a samarium compound in an amount of 0.01 to 10% by weight based on the total composition. The resin composition of the present invention is achieved by incorporating a samarium compound into a methacrylic resin containing methyl methacrylate as a main component. Therefore, the method for obtaining the composition of the present invention is not particularly limited, and various manufacturing methods can be applied. For example, a method of blending a samarium compound and a methacrylic resin, a method of mixing and polymerizing a samarium compound with a monomer whose main component is methyl methacrylate or a partial polymer thereof, or a method of blending a samarium compound with a monomer whose main component is methyl methacrylate or a method of polymerizing a samarium compound with a monomer whose main component is methyl methacrylate. The polymer may be polymerized by mixing it with a partially polymerized product thereof and a solvent. The resin forming raw material used to constitute the resin composition of the present invention is a methyl methacrylate monomer, a monomer mixture containing methyl methacrylate as a main component, or a partial polymer thereof. The monomer mixture containing methyl methacrylate as a main component consists of methyl methacrylate and another vinyl monomer copolymerizable with methyl methacrylate. Other vinyl monomers copolymerizable with methyl methacrylate are not particularly limited, but include those having 1 to 4 carbon atoms.
alkyl acrylate, alkyl methacrylate having 2 to 4 carbon atoms, styrene, α-methylstyrene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, tetraethylene glycol dimethacrylate, tetraethylene glycol acrylate, Examples include pentaerythritol tetramethacrylate, pentaerythritol tetraacrylate, allyl acrylate, allyl methacrylate, and the like. The amount of these used is 50% by weight or less in the monomer mixture. Further, it is desirable that the polymer content in the partially polymerized resin raw material used be as small as possible so as not to impair the optical properties of the finally obtained polymer. The samarium used in making up the compositions of the present invention may include samarium compounds such as samarium oxide, samarium carbonate, samarium hydroxide,
Alternatively, samarium salts of inorganic or organic acids such as samarium nitrate, samarium methacrylate, and samarium acrylate obtained by reacting samarium oxide with an inorganic or organic acid, or samarium oxide and acetylacetone, or benzoylacetone Examples include gadolinium complex compounds such as tris(acetylacetonato)samarium or tris(benzoylacetonato)samarium obtained by reacting with the like. The amount of these samarium compounds used is such that the weight concentration of samarium atoms is 0.01 to 10% by weight based on the total weight of the resin composition.
Preferably 1 to 5% by weight is desirable. 0.01% by weight
If it is less than 10% by weight, the resulting resin composition will have little neutron beam shielding effect, and if it exceeds 10% by weight, the optical properties or mechanical strength will deteriorate. These samarium compounds cannot be determined unconditionally depending on the application, but they can be blended with methacrylic resin, mixed with resin-forming raw materials and polymerized, or mixed with resin-forming raw materials and a solvent and polymerized to form methacrylic resin. It can be contained inside. Particularly, the method using the latter solvent is suitable for obtaining transparent resin products without scattering. When blended with a samarium compound or added to a resin forming raw material, preferred examples include those selected from samarium oxide, samarium carbonate, samarium hydroxide compounds, and samarium complex compounds. In addition, when using a samarium compound in a mixture with a resin-forming raw material and a solvent, samarium nitrate, samarium methacrylate, or samarium acrylate obtained by reacting samarium oxide with an inorganic or organic acid can be used. Tris(acetylacetonato)samarium or tris(benzoylacetonato)samarium obtained by reacting samarium salts of inorganic or organic acids such as samarium salts and their double salts, or samarium oxides with acetylacetone, benzoylacetone, etc. Preferred examples include samarium complex compounds such as . The solvent used when producing the resin composition of the present invention has the following general formula K0018 (where R ₁ is a saturated carbon number of 1 to 20 or an unsaturated hydrocarbon residue) K0019 (wherein, R ₂ is hydrogen or a saturated or unsaturated hydrocarbon residue having 1 to 9 carbon atoms, and R ₃ is a saturated or unsaturated hydrocarbon residue having 1 to 9 carbon atoms)
K0020 (In the formula, R ₄ is hydrogen or a methyl group, A ₁ is an alkyl group having 2 to 6 carbon atoms, and n is 0 or an integer of 1 to 10. ) K0021 (In the formula, R ₅ is hydrogen or a methyl group, R ₆ is an alkylene group having 2 to 6 carbon atoms) R ₇ −OH (5) or (In the formula, R ₇ is a saturated group having 3 to 10 carbon atoms) or an unsaturated hydrocarbon residue) R ₈ (-A ₂ -O)- _n H (6) (wherein, R ₈ is a hydroxyl group or a saturated or unsaturated hydrocarbon residue having 1 to 10 carbon atoms) , _A2 is an alkylene group having 2 to 4 carbon atoms, m is an integer of 2 to 10). The solvents represented by the general formulas (1), (2), (3), (4), (5) and (6) are co-solvents for uniformly dissolving the samarium compound in the resin forming raw material. , unsaturated carboxylic acids such as methacrylic acid and acrylic acid, saturated or unsaturated fatty acids such as propionic acid, octylic acid, isobutyric acid, hexanoic acid, octylbenzoic acid, stearic acid, palmitic acid, naphthenic acid, 2-hydroxyethyl Examples include unsaturated alcohols such as acrylate and 2-hydroxyethyl methacrylate, saturated aliphatic alcohols such as propyl alcohol and cyclohexyl alcohol, and glycols such as ethylene glycol, diethylene glycol and propylene glycol. Among these solvents, monomers copolymerizable with methyl methacrylate, such as methacrylic acid, acrylic acid, 2-hydroxyethyl methacrylate, and 2-hydroxyethyl acrylate, are preferred. These solvents can be used alone or in combination of two or more. The amount of the solvent used in the present invention cannot be determined unconditionally depending on the type and amount of the samarium compound used, but is preferably 40% by weight or less, and preferably 40% by weight or less.
It is 10% by weight or less. If the amount used exceeds 40% by weight, the mechanical and thermal properties of the resulting resin composition will deteriorate, which is not preferred. Examples of the polymerization initiator used in the present invention include peroxides such as benzoyl peroxide and lauroyl peroxide, 2,2'-azobisisobutyronitrile, 2,2'-azobis-(2,4
Known radical initiators such as azobis-based initiators such as -dimethylvaleronitrile) and 2,2'-azobis-(2,4-dimethyl-4-methoxy-valeronitrile) can be used. These polymerization initiators can be used alone or in combination of two or more, and the amount used is 0.001 to 0.1 per 100 parts by weight of resin raw material.
Parts by weight. The polymerization method used to obtain the resin composition of the present invention is not particularly limited, but cast polymerization is a preferred polymerization method. In the case of this cast polymerization, the polymerization mixture prepared from the above components (a), (b) and (c) is mixed with a soft material such as an inorganic glass plate, stainless steel plate, nickel chrome plate or aluminum plate. The mixture is injected into a mold consisting of a vinyl chloride gasket and allowed to polymerize. Cast polymerization is
0.3-15 hours at 45-95℃, followed by 10 hours at 100-145℃
Polymerization is completed over a period of minutes to 5 hours. In the present invention, if necessary, an ultraviolet absorber,
A mold release agent, a heat stabilizer, a coloring agent, a light diffusing agent, and other neutron shielding compounds, lead compounds, etc. can also be added. The samarium-containing methacrylic resin composition of the present invention, which has the structure described above and has excellent optical and mechanical properties, can be easily produced in the same manufacturing process as general acrylic resins, and is resistant to radiation mainly composed of neutrons. Can be used as a shielding material. Furthermore, when a lead compound is used in combination with the composition of the present invention, X-rays, γ-rays,
It becomes possible to shield from both neutron beams. Although the methacrylic resin composition of the present invention is particularly useful as a neutron shielding material, it can also be used in other applications such as optical filters, optical lenses, light conversion materials, lighting materials, and the like. EXAMPLES Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited thereto. Reference Example 1 Synthesis of samarium methacrylate 0.3 g of hydroquinone monomethyl ether as a polymerization inhibitor was uniformly dissolved in a mixture of 280 g of methacrylic acid and 1000 g of toluene, and after heating this to 60°C, 174 g of samarium oxide powder was added to this solution.
g over 20 minutes and continued stirring for 1 hour. The reaction solution was then allowed to stand for one day, and then filtered.
The liquid is removed to obtain samarium methacrylate. The yield was 370g. Reference Example 2 Synthesis of samarium nitrate A slight excess of samarium oxide is heated and dissolved in concentrated nitric acid and reacted. After 1 hour, the liquid was cooled to precipitate samarium nitrate crystals. The yield was 60%. Reference example 3 Synthesis of tris(acetylacetonato)samarium 100 c.c. of acetylacetone and 180 g of samarium oxide
was suspended in 3000 c.c. of anhydrous diethyl ether and refluxed for 2 hours, followed by distillation and removal of diethyl ether to obtain crystals of tris(acetylacetonato)samarium. The yield was 65%. Example 1 3 g of samarium nitrate synthesized in Reference Example 2 was mixed with 2-
It is dissolved in a mixed solution of 17 g of hydroxyethyl methacrylate and 2 g of propylene glycol, and 78 g of methyl methacrylate is added to this solution and mixed by stirring. This liquid mixture was a transparent liquid. Next, add 0.04g of 2 as a polymerization catalyst to this mixed solution.
After adding and dissolving 2'-azobis-(2,4-dimethylvaleronitrile) and 0.005 g of dioctyl sulfosuccinate sodium salt as a mold release agent, it was degassed and the plate thickness was set in advance to 3 mm. The mold was poured into a conventional inorganic glass mold, and the mold was immersed in warm water at 65°C for 180 minutes, and then kept in an air bath at 110°C for 120 minutes to complete polymerization. The resin plate taken out from the mold was transparent. Example 2 1.5 g of samarium nitrate synthesized in Reference Example 2 was
-Dissolve in 8.5 g of hydroxyethyl methacrylate, and then add this to 90 g of methyl methacrylate and mix with stirring. This mixture was transparent.
The same type and amount of polymerization catalyst and mold release agent as used in Example 1 were added to this mixed solution, and cast polymerization was carried out under the same conditions as in Example 1. The obtained resin plate was transparent. Example 3 1.5 g of tris(acetylacetonato)samarium synthesized in Reference Example 3 is dissolved in 8.5 g of methacrylic acid, and this solution is added to 90 g of methyl methacrylate and mixed by stirring. The same polymerization catalyst and mold release agent as in Example 1 were added to this mixed solution, and the same cast polymerization as in Example 1 was performed.
After the polymerization was completed, the resin plate peeled off from the mold was transparent although it had a very slight yellow color. Example 4 Samarium methacrylate 8 synthesized in Reference Example 1
g, n-octylic acid 2g, propylene glycol 1g, 2-hydroxyethyl methacrylate 1
g, 5 g of styrene and 83 g of methyl methacrylate
were mixed, and cast polymerization was repeated under the same polymerization conditions as in Example 1. The resulting resin plate was slightly yellow but transparent. Example 5 Partial polymer of methyl methacrylate (polymerization rate 18
%) 100 parts by weight, α,α′-azobis-(2,4-dimethylvaleronitrile) 0.04 as a polymerization catalyst
Parts by weight, 0.005 parts by weight of dioctyl sulfosuccinate sodium salt as a mold release agent, average particle size 2μ
Add and mix 2.0 parts by weight of samarium oxide,
After degassing, it was poured into a mold made of tempered glass with a thickness of 3 mm and a soft vinyl chloride gasket, immersed in hot water at 70°C for 60 minutes, and then placed in an air bath at 130°C. The polymerization was completed after being left for 80 minutes to obtain a resin plate. Example 6 Average particle size per 100 parts by weight of methacrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., trade name Acrypet VH)
Add 2.0 parts by weight of samarium hydroxide with a particle size of 0.5μ and 1.0 parts by weight of samarium carbonate with an average particle size of 2μ, mix thoroughly in a tumbler to make the mixture homogeneous, and then extrude it from an extruder using a conventional method to obtain a sheet with a thickness of 3 mm. Ta. The results of total light transmittance (%), haze value (%), bending fracture strength (Kg/cm ² ), and neutron shielding ability (thermal neutron absorption cross section) of the methacrylic resin plates obtained in Examples 1 to 7 are shown below. It is shown in Table 1. In addition, total light transmittance and haze value are ASTM-D
-1003-61, bending fracture strength was measured according to ASTM-D-790. The thermal neutron absorption cross section was determined using the numerical values described in Experimental Chemistry Course (12) Radiochemistry (Maruzen) and the following formula. S = (W ₁ /M ₁ ×S ₁ +W ₂ /M ₂ ×S ₂ +... + Wn / Mn × Sn) × N However, S Thermal neutron absorption cross section per 100g of composition (cm ² ) Mi i species Atomic weight of element Wi Abundance of i-type element Si Thermal neutron absorption cross section of i-type element (barns) N Avogadro's number (i=1...n)

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Claims (1)

[Scope of Claims] 1. A methacrylic resin composition containing a samarium compound in a methacrylic resin whose main component is methyl methacrylate so that the weight concentration of samarium atoms is 0.01 to 10% by weight based on the total composition. thing. 2 (a) Methyl methacrylate monomer or a monomer mixture containing methyl methacrylate as a main component,
or a resin-forming raw material selected from partial polymers thereof, (b) a samarium compound in an amount such that the weight concentration of samarium atoms is 0.01 to 10% by weight based on the total composition, and (c) a polymerization mixture consisting of a polymerization initiator. 1. A method for producing a methacrylic resin composition, which comprises polymerizing a methacrylic resin composition. 3. The method for producing a methacrylic resin composition according to claim 2, wherein the samarium compound is selected from samarium oxide, samarium carbonate, samarium hydroxide, and a complex compound of samarium. 4 The following general formula showing solubility in resin forming raw materials and samarium compounds K0014 (In the formula, R ₁ is a saturated or unsaturated hydrocarbon residue having 1 to 20 carbon atoms) K0015 (In the formula, R ₂ is hydrogen or a saturated or unsaturated hydrocarbon residue having 1 to 9 carbon atoms, R ₃ is hydrogen or a saturated or unsaturated hydrocarbon residue having 1 to 9 carbon atoms;
4 saturated or unsaturated hydrocarbon residues. ) K0016 (In the formula, R ₄ is hydrogen or a methyl group, A ₁ is an alkyl group having 2 to 6 carbon atoms, and n is 0 or an integer of 1 to 10) K0017 (In the formula, R ₅ is hydrogen or a methyl group , R ₆ is an alkylene group having 2 to 6 carbon atoms) R ₇ -OH (5) (wherein, R ₇ is a saturated or unsaturated hydrocarbon residue having 3 to 10 carbon atoms) or R ₈ (-A2 _- O) _-nH (6) (wherein, _R8 is a hydroxyl group or a saturated or unsaturated hydrocarbon residue having 1 to 10 carbon atoms, _A2 is an alkylene group having 2 to 4 carbon atoms, The method for producing a methacrylic resin composition according to claim 2, characterized in that the polymerization is carried out by adding at least one solvent selected from the following (m is an integer of 2 to 10). 5. The method for producing a methacrylic resin composition according to claim 4, wherein the samarium compound is selected from samarium nitrate, a samarium salt of an organic acid, or a samarium complex compound. 6 The samarium compound is selected from samarium methacrylate, samarium acrylate or samarium tris(acetylacetonato), and the solvent is octylic acid and propylene glycol and/or 2-hydroxyethyl methacrylate or 2-hydroxyethyl acrylate. The fourth claim characterized in that
A method for producing a methacrylic resin composition as described in Section 1.