JP6259950B2 - Polyurethane resin for water equivalent phantom materials - Google Patents

Description

  The present invention relates to a polyurethane resin for a water equivalent phantom material. More specifically, the present invention relates to a water-equivalent phantom material that is highly equivalent to water, has good machinability, and is easy to handle.

  A substance that can be easily obtained in nature as a phantom material having physical properties (effective atomic number and material density) most similar to human soft tissue is water, but since it is a liquid, it is inconvenient to handle. Water-equivalent solid phantom materials have been developed. As this type of solid phantom material, for example, a material mainly composed of paraffin and a material mainly composed of an epoxy resin are known. A material comprising an epoxy resin, calcium carbonate, and a microballoon of vinylidene chloride / acrylonitrile copolymer has been developed (Patent Document 1).

JP-A-1-202683

However, the material whose main component is paraffin is not suitable for use at high temperatures and is liable to break. In addition, since the material composed of epoxy resin is hard and brittle as a characteristic of the resin, it is easy to “chip” during cutting and handling, especially when using a thin phantom, etc. Care was required in handling.
An object of the present invention is to provide a polyurethane resin for water-equivalent phantom materials that has high water equivalence and excellent mechanical strength and flexibility.

The inventors of the present invention have arrived at the present invention as a result of intensive studies to solve the above problems. That is, the present invention relates to a polyurethane resin which is a reaction product of a polyurethane resin-forming composition containing a polyol (a) and a polyisocyanate (b) , an inorganic filler composed only of elements having atomic numbers 1 to 40 (d ) And an organic filler (c), wherein (d) is a hydroxide, oxide, or peroxide of at least one element selected from the group consisting of magnesium, aluminum, and silicon , Carbonides, carbonates, nitrates, sulfates, chlorides or silicates , each content based on the total weight of (a), (b), (c) and (d) is (a) 30 to 65%, (b) is 15 to 45%, (c) is 5 to 50%, (d) is 1 to 30%, and the effective atomic number (n) obtained by the following formula (1) is Radiation that is 7.0-8.0 Ryoyo water equivalent phantom material for the polyurethane resin composition is (Q).

[In Formula (1), (t) is a coefficient (3.5), (fi) is the ratio of the number of electrons of the i-th atom in the atoms constituting the resin to the number of electrons of the whole atoms constituting the resin. , (Zi) is the atomic number of the i-th atom among the atoms constituting the resin. ]

The polyurethane resin for water equivalent phantom materials of the present invention has the following effects.
(1) High equivalence with reference organization (water).
(2) It has excellent mechanical strength and flexibility, and is easy to handle because “cracks” and “chips” are less likely to occur.
(3) Good machinability.
The mechanical strength can be evaluated by impact strength described later, the flexibility can be evaluated by bending elastic modulus described later, and the cutting workability can be evaluated by cutting resistance described later.

[Polyol (a)]
Examples of the polyol (a) in the present invention include the following (a1), (a2) and a mixture thereof.
(A1) Polyoxyalkylene polyol Starting materials (for example, polyhydric alcohols such as ethylene glycol, glycerin and propylene glycol, amines such as triethanolamine, ethylenediamine and toluenediamine, polyhydric phenols such as bisphenol A and bisphenol F, and the like) 2) is added to an alkylene oxide (hereinafter abbreviated as AO), and the added AO is preferably a compound having 2 to 8 carbon atoms. Propylene oxide (hereinafter abbreviated as PO), ethylene oxide (Hereinafter abbreviated as EO), butylene oxide (hereinafter abbreviated as BO), and the like may be used. Two or more kinds may be used, but preferred are PO, EO, and a mixture of PO and EO. The number of moles of AO added is not particularly limited, but is usually 1 to 20 moles, preferably 2 to 10 moles.

(A2) Polyester polyol The polyhydric alcohol [particularly, a dihydric alcohol such as ethylene glycol, diethylene glycol, propylene glycol, 1,3- or 1,4-butanediol, 1,6-hexanediol, neopentyl glycol; Polyether polyols (particularly diols); or a mixture of these with trihydric or higher polyhydric alcohols such as glycerin and trimethylolpropane; and polycarboxylic acids or ester-forming derivatives thereof [acid anhydrides, lower alkyls ( Condensation of polyester polyol with adipic acid, sebacic acid, maleic anhydride, phthalic anhydride, dimethyl terephthalate, or the carboxylic anhydride and AO Reactants; their AO Adducts (EO, PO, etc.); polylactone polyols, such as those obtained by ring-opening polymerization of lactones (e.g., ε-caprolactone) using the polyhydric alcohol as an initiator; polycarbonate polyols, such as the polyhydric alcohol and alkylene A reaction product with carbonate; and the like. In addition, naturally occurring polyester polyols include those containing castor oil, castor oil derivatives, and mixtures thereof. Castor oil refers to natural vegetable oil extracted from the seeds of Euphorbiaceae. However, it is preferably purified for industrial raw materials in order to reduce the inhibition of urethane reaction and the occurrence of side reactions. The castor oil derivative is a castor oil derivative obtained by reacting castor oil with another compound, and has a molecular weight of 1,000 to 1,500. Is preferred. Castor oil derivatives include compounds obtained by adding AO to castor oil. AO preferably has 2 to 8 carbon atoms, and includes EO, PO, BO, etc., and two or more kinds may be used.

Among the above (a), from the viewpoint that the mechanical strength and the effective atomic number are small, and it is easy to obtain an effective atomic number specified later, (a2) [(a) among (a) is preferably 30% by weight or more, more preferably 40% by weight or more], more preferably castor oil [of (a), castor oil is 30% by weight or more, more preferably 40% by weight or more].

The number average molecular weight of the polyol (a) is usually 200 to 3,000, preferably 250 to 2,000, more preferably 300 to 1,500, from the viewpoint of the balance between the resin strength and the flexibility. The average functional group number of (a) is usually 2-8, preferably 2-6. The average hydroxyl value of (a) is usually 56 to 900, preferably 150 to 700.
The number average molecular weight is usually calculated from the hydroxyl value of the polyol (a) and the valence of the polyol. The hydroxyl value in the present invention is measured by a method defined in JIS K0070 (1995 edition).

[Polyisocyanate (b)]
The polyisocyanate (b) in the present invention is not particularly limited as long as it is a compound having two or more isocyanate groups in the molecule. Examples of (b) include aromatic polyisocyanate (b1), aliphatic polyisocyanate (b2), alicyclic polyisocyanate (b3), araliphatic polyisocyanate (b4), and modified products (b5) (for example, Urethane group, carbodiimide group, allophanate group, urea group, burette group, isocyanurate group, or oxazolidone group-containing modified product). (B) may be used alone or in combination of two or more.

The aromatic polyisocyanate (b1) includes 6 to 16 aromatic diisocyanates, 6 to 20 aromatic triisocyanates, and these isocyanates (excluding carbon in the NCO group; the same as the following isocyanates). Examples include crude products. Specific examples include 1,3- and / or 1,4-phenylene diisocyanate, 2,4- and / or 2,6-tolylene diisocyanate (TDI), crude TDI, 2,4′- and / or 4, 4'-diphenylmethane diisocyanate (MDI), polymethylene polyphenylene polyisocyanate (crude MDI or polymeric MDI), and the like.
Examples of the aliphatic polyisocyanate (b2) include aliphatic diisocyanates having 6 to 10 carbon atoms. Specific examples include 1,6-hexamethylene diisocyanate and lysine diisocyanate.
Examples of the alicyclic polyisocyanate (b3) include alicyclic diisocyanates having 6 to 16 carbon atoms. Specific examples include isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate, norbornane diisocyanate, and the like.
Examples of the araliphatic polyisocyanate (b4) include araliphatic diisocyanates having 8 to 12 carbon atoms. Specific examples include xylylene diisocyanate, α, α, α ′, α′-tetramethylxylylene diisocyanate, and the like. Specific examples of the modified polyisocyanate include urethane-modified MDI and carbodiimide-modified MDI.

  Among the above (b), from the viewpoint that the effective atomic number is small and the effective atomic number specified later is easily obtained, the aliphatic polyisocyanate (b2), the alicyclic polyisocyanate (b3) and a modified product thereof are preferable. Further, (b2) and (b3) are more preferable, and (b3) is particularly preferable. The isocyanate group content in the polyisocyanate (b) is preferably 10 to 40% by weight.

[Organic filler (c)]
The organic filler (c) in the present invention can be used as long as it is used for generally used organic fillers, and specifically, polystyrene, polyacrylonitrile, polymethyl methacrylate, polypropylene, polyethylene, polyvinyl chloride. Synthetic organic fine particles such as wood powder, bamboo powder, sawdust, paper pulp, and natural organic fine particles such as wood-purified cellulose powder obtained from paper pulp.
Among the above (c), from the viewpoint that the effective atomic number is small and it is easy to obtain an effective atomic number defined later, polyolefin resin fine particles such as polyethylene and polyethylene are preferable, and polypropylene fine particles are more preferable.
The volume average particle size (measured by a laser diffraction particle size analyzer) of (c) is not particularly limited, but is preferably 0.1 to 500 μm, more preferably 1 to 300 μm, and particularly preferably 5 to 100 μm.
When the particle diameter of (c) is 0.1 to 500 μm, the appearance of the surface is not impaired even when the particles are located on the outer surface of the molded product, and there is little rise of fine dust during powder handling or product cutting. Therefore, it is preferable in the working environment.

[Inorganic filler (d)]
The inorganic filler (d) in this invention is a compound comprised only from the element of atomic number 1-40. (D) is preferably one having at least one element selected from the group consisting of magnesium, aluminum, silicon, and calcium as an essential constituent element.
(D) is an essential constituent element of the above element, and is a hydroxide, oxide, peroxide, carbonized product, carbonate, nitrate, sulfate, chloride, phosphate, silicate Etc.
Of the above (d), preferred are oxides (for example, silicon oxide), carbonates (for example, calcium carbonate), hydroxides (for example, magnesium hydroxide), sulfates (for example, calcium sulfate), chlorides (for example, chloride) Calcium) and silicates (for example, talc, molecular sieve 3A-B).
Further, among (d), more preferable are magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium chloride, aluminum hydroxide, aluminum oxide, aluminum chloride, aluminum sulfate, silicon oxide, calcium carbonate, calcium sulfate, and hydroxide. Calcium, calcium chloride, talc, and molecular sieve (aluminosilicate) are particularly preferred from the viewpoints of machinability, chemical stability (low water solubility), and availability. Aluminum, talc, calcium carbonate, silicon oxide.
The volume average particle diameter (measured by a laser diffraction particle size analyzer) of (d) is not particularly limited, but is preferably 0.01 to 100 μm, more preferably 0.1 to 50 μm, and particularly preferably 1 to 30 μm. is there. When the particle diameter of (c) is 0.01 to 100 μm, the surface appearance is not impaired even if the particles are located on the outer surface of the molded product, and the dispersibility of the particles in the resin is good.

[Polyurethane resin-forming composition]
The polyurethane-forming composition in the present invention contains the inorganic filler (d) composed only of the polyol (a), the polyisocyanate (b), and an element having an atomic number of 1 to 40.

The polyurethane-forming composition preferably further contains the organic filler (c) from the viewpoints of water equivalence (effective atomic number) and mechanical strength.
Each content based on the total weight of (a), (b), (c) and (d) is preferably from 30 to (a) from the viewpoint of water equivalence (effective atomic number) and mechanical strength. 65%, more preferably 35-60%; (b) is preferably 15-45%, more preferably 20-40%; (c) is preferably 5-50%, more preferably 10-45%; d) is preferably 1 to 30%, more preferably 3 to 20%.
In order to achieve water equivalent (effective atomic number specified later), for example, considering the effective atomic number of the organic fillers (c) and (d), it is appropriately determined depending on the types and amounts of (c) and (d). Can be adjusted. Further, the density of the molded product to be described later can be appropriately adjusted depending on the types and amounts of the organic fillers (c) and (d).

  The polyurethane resin-forming composition contains, as necessary, a urethanization catalyst (F), an additive (G), etc., which are generally used for urethane resin production, as long as the effects of the present invention are not impaired. May be.

[Urethaneization catalyst (F)]
As the urethanization catalyst (F) in the present invention, all usual urethanization catalysts that promote the urethanation reaction can be used. Examples include triethylenediamine, bis (N, N-dimethylamino-2-ethyl) ether, N , N, N ′, N′-tetramethylhexamethylenediamine, tertiary amines such as PO adduct of N, N-dimethylaminopropylamine and carboxylates thereof, potassium acetate, potassium octylate, stannous octoate, etc. Organic metal compounds such as carboxylic acid metal salts and dibutyltin dilaurate. The addition amount of the urethanization catalyst (F) is usually 0.0001% to 1.0%, preferably 0.001% to 0.5% based on the weight of the polyurethane resin-forming composition.

[Additive (G)]
As additives (G) in the present invention, hollow particles (microballoons) (G1), lubricants (G2), plasticizers (G3), thixotropic agents (G4), foaming agents (G5), ultraviolet absorbers ( G6), anti-aging agent (G7), antioxidant (G8), colorant (G9), flame retardant (G10), antifungal agent (G11), antibacterial agent (G12), dispersant (antisettling agent) ( G13), an antifoamer (G14), and 1 type, or 2 or more types of additives chosen from the group which consists of surfactant (G15) are mentioned.
The (G1) is an inorganic and / or organic hollow particle having a true specific gravity of 0.6 or less, more preferably a true specific gravity of 0.1 to 0.5. The (G1) and the above (c) and (d) can be distinguished by true specific gravity.
The amount of each type (G) added is usually 3% or less, preferably 2% or less, based on the weight of the polyurethane resin-forming composition. Further, the total amount of addition of (G) is usually 10% or less, preferably 5% or less, more preferably 3% or less, based on the weight of the polyurethane resin-forming composition.

[Polyurethane resin for water equivalent phantom material (Q)]
The urethane resin (Q) for water-equivalent phantom of the present invention is a polyurethane resin that is a reaction product of the polyurethane resin-forming composition, and the effective atomic number (n) obtained by the following formula (1) is 7 It is 0.0 to 8.0, more preferably 7.2 to 7.8, and particularly preferably 7.3 to 7.6.
That is, the (Q) comprises the inorganic filler (d) composed only of the polyol (a), the polyisocyanate (b), and an element having an atomic number of 1 to 40, preferably (a), ( b), (d) and a polyurethane resin comprising organic filler (c) as constituents, and a polyurethane resin for water-equivalent phantom material having the specific effective atomic number (n).
When the effective atomic number (n) is out of the range, the water equivalence of (Q) is inferior. In the present invention, the effective atomic number (n) is obtained by the following formula (1).

However, in Formula (1),
(T): Coefficient (3.5)
(Fi): The ratio of the number of electrons of the i-th atom among the atoms constituting the resin to the number of electrons of the whole atoms constituting the resin.
(Zi): Atomic number of i-th atom among atoms constituting resin

  Also, because of the difference in the amount of radiation absorption in the resin, there is a possibility that a secondary image that is not an actual image called “metal artifact” may occur in the CT measurement process. The element is preferably at most 0.5% by weight, more preferably at most 0.1% by weight, particularly preferably at most 0.05% by weight, based on the weight of the polyurethane resin (Q).

  Although it does not specifically limit as a manufacturing method of the said polyurethane resin (Q), For example, the polyol component formed by containing a polyol (a) and the polyisocyanate component formed by containing a polyisocyanate (b) are mixed. A method of obtaining (Q) by obtaining a mixed liquid and reacting and curing by heating (for example, 100 ° C.) as necessary may be mentioned. In the production method, the organic filler (c) is preferably contained in each of the polyol component and the polyisocyanate component, and the urethanization catalyst (F) and the inorganic filler (d) are preferably contained in the polyol component. .

  Moreover, the manufacturing conditions in particular of polyurethane resin (Q) are not restrict | limited, A well-known condition is applied. The isocyanate index [(NCO group / active hydrogen atom-containing group equivalent ratio × 100) (NCO index) in the production of the polyurethane resin is preferably 70 to 125, more preferably 75 to 120, and particularly preferably 85 to 115. It is.

  A specific example of the method for producing the polyurethane resin (Q) of the present invention is as follows. First, an inorganic filler (d), an organic filler (c), a urethanization catalyst (E), an additive (G), etc. are mix | blended with a polyol (a). Simultaneously, an organic filler (c), an additive (G), etc. are mix | blended with polyisocyanate (b). Next, using a polyurethane foaming machine or a mixer, the polyol compounded liquid and the polyisocyanate compounded liquid are mixed at high speed, and heated (for example, at 100 ° C.) as necessary to obtain the polyurethane resin (Q).

[Polyurethane resin molded product for water equivalent phantom materials (Z)]
The polyurethane resin molded product (Z) for water-equivalent phantom material of the present invention is a molded product of the polyurethane resin (Q).
That is, the polyurethane resin molded product (Z) for water-equivalent phantom material is obtained by molding (Q), that is, by performing processing such as cutting, cutting, cutting, and polishing as necessary.
Also, a polyurethane resin can be obtained by pouring a mixed solution (polyurethane-forming composition) comprising a polyol component and a polyisocyanate component in the above production method into a mold, etc., reacting and curing the mixed solution, and heating as necessary. (Q) may be obtained, and this may be used as a polyurethane resin molded product (Z) for a water equivalent phantom material.

The density (unit: g / cm ³ ) of the polyurethane resin molded product (Z) is preferably 0.95 to 1.05 from the viewpoint of water equivalence since the density of water at 25 ° C. is 1.00. .
Further, the hardness of the polyurethane resin molded product (Z) by a type D durometer is preferably 40 to 90, more preferably 50 to 85, and particularly preferably 60 to 80 from the viewpoint of cutting workability. If the hardness is 40 or more, there is little deformation of the molded product at the time of cutting and handling, and the dimensional accuracy of the molded product can be maintained, and if it is 90 or less, the cutting resistance is small and the cutting speed can be increased. Good cutting workability.

  The polyurethane resin (Q) for water-equivalent phantom material and the polyurethane resin molded product (Z) for water-equivalent phantom material of the present invention are urethane resin molding having high equivalence to the reference structure (water) and having both strength and flexibility. Because it is a product, it is a water-equivalent phantom material that has few chipping during handling and handling, has good machinability and is easy to handle, and is particularly suitable as a water-equivalent phantom material for radiation therapy.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these. In the following, parts represent parts by weight.

The polyurethane resin raw materials in Examples and Comparative Examples are as follows. In the table, raw materials are described only by symbols.
<Polyol (a)>
Polyol (a-1):
Castor oil ["castor oil SL", manufactured by Ito Oil Co., Ltd.,
Average functional group number 2.7, number average molecular weight 950, hydroxyl value 160,
Specific gravity 0.96]
Polyol (a-2):
PO addition product of glycerin [average functional group number 3.0, number average molecular weight 250,
Hydroxyl value 670, specific gravity 1.09]
Polyol (a-3):
PO addition product of glycerin [average functional group number 3.0, number average molecular weight 400,
Hydroxyl value about 420, specific gravity 1.06]

<Polyisocyanate (b)>
Polyisocyanate (b-1):
Isophorone diisocyanate ["VESTANAT IPDI",
EVONIC Co., Ltd., isocyanate group content 37.6% by weight,
Specific gravity 1.06]
Polyisocyanate (b-2):
Polymeric MDI isocyanate [“Luprinate M-20S”],
BASF Japan Ltd., isocyanate group content 31% by weight,
Specific gravity 1.24]

<Organic filler (c)>
Organic filler (c-1):
Polypropylene powder ["Ceraflower 915"
Big Chemie Japan Co., Ltd., volume average particle size of about 34 μm,
True specific gravity 0.90]
Organic filler (c-2):
Polyethylene powder ["Flow Beads LE-1080",
Manufactured by Sumitomo Seika Co., Ltd., volume average particle diameter of about 11 μm, true specific gravity of 0.92]

<Inorganic filler (d)>
Inorganic filler (d-1):
Magnesium hydroxide ["Magnesium hydroxide # 300",
Manufactured by Kamishima Chemical Industry Co., Ltd., volume average particle diameter of about 7 μm, true specific gravity of 2.36]
Inorganic filler (d-2):
Aluminum hydroxide ["Hijilite H32", manufactured by Showa Denko KK
Volume average particle diameter of about 8μm, true specific gravity 2.42]
Inorganic filler (d-3):
Talc ["Soap Stone A" manufactured by Nippon Mistron,
Volume average particle diameter of about 4 μm, true specific gravity of 2.7]
Inorganic filler (d-4):
Calcium carbonate ["Whiteon SB red" manufactured by Shiraishi Calcium Co., Ltd.
Volume average particle diameter of about 2 μm, true specific gravity of 2.7]
Inorganic filler (d-5):
Molecular sieve [Molecular sieve 3A-B powder]
Union Showa Co., Ltd., true specific gravity 1.86]
Inorganic filler (d-6):
Silicon oxide ["Cycilia 430", manufactured by Fuji Silysia Chemical Ltd.,
Volume average particle diameter of about 3 μm, true specific gravity of 2.65]

<Urethaneization catalyst (F)>
Urethane catalyst (F-1):
Bismuth 2-ethylhexanoate ["Neostan U-600",
Nitto Kasei Co., Ltd.]
<Additive (G)>
Microballoon (G-1):
["Matsumoto Microsphere MFL-81GCA",
Matsumoto Yushi Seiyaku Co., Ltd., volume average particle size 20 μm, true specific gravity 0.23]

<Examples 1-9, 11-15, Comparative Examples 2-4>
Using a commercially available vacuum stirring deaerator, the parts by weight of the polyol component and polyisocyanate component shown in Table 1 were mixed / stirred under vacuum. The rotational speed of the apparatus was 300 rpm, and the stirring time was 15 minutes. The mixed liquid is poured into a mold having a size of 300 mm (vertical) × 300 mm (width) × 100 mm (height) × 100 mm in height, and cured in a curing furnace at 100 ° C. for 10 hours, thereby forming the polyurethane resin molded product (Z-1) to ( Z-9), (Z-11) to (Z-15), (Ratio Z-2) to (Ratio Z-4) were obtained.

<Example 10>
Using a mechanical froth foaming machine (manufactured by Toho Machine Industry Co., Ltd., MF-350 type), the polyol component and polyisocyanate component in parts by weight shown in Table 1 were continuously mixed together with nitrogen, and then the polyol component and polyisocyanate. The components were mixed in the number of parts shown in Table 1, and the mixture was discharged. The rotational speed of the mechanical floss head at this time was 300 RPM, and the nitrogen flow rate was 1.3 L / min. The liquid feed ratio [NCO / OH equivalent ratio] of the polyol component blend liquid and the isocyanate component blend liquid was 1.05 / 1, and the liquid feed speed was 1 L / min.
Since the liquid mixed in the mixer unit is continuously supplied from the discharge port, a metal mold is attached to the discharge port in advance, the supplied mixed solution is received, and the received mixed solution is sent to the curing furnace. The polyurethane resin molded product (Z-10) was obtained by curing at 100 ° C. for 10 hours.

In Comparative Example 1, a commercially available epoxy resin molded product for water equivalent phantom material (ratio Z-1) was used.
In Comparative Example 5, water was used for comparison (ratio Z-5).

About the obtained polyurethane resin molded product, the physical property was measured with the measuring method shown below. The evaluation results are shown in Table 1.
<Test method>
(1) Density (g / cm ³ )
A 200 mm × 100 mm × 30 mm test piece is cut out from the center of the rectangular parallelepiped molded product, and the weight of the test piece is divided by the volume calculated from the product of the lengths of the three sides in a temperature-controlled room at 25 ° C. And density.
(2) Hardness [Evaluation of mechanical strength]
A rectangular parallelepiped shaped product was measured five times with a type D durometer in accordance with JIS K6253 to obtain an average value, and this was taken as the hardness.

(3) Flexural modulus (MPa) [Evaluation of flexibility]
A 200 mm x 100 mm x 30 mm test piece is cut to 80 mm x 10 mm x 4 mm to obtain a test piece for bending strength evaluation. According to JIS K6911 (1995 edition), "Instron type universal" manufactured by Shimadzu Corporation The bending elastic modulus was measured in a room temperature-controlled at 25 ° C. using a “tester”.
(4) Cutting resistance (N) [Evaluation of cutting workability]
A 200 mm x 100 mm x 30 mm test piece is cut into 80 mm x 30 mm x 10 mm to obtain a test piece for cutting resistance evaluation, and is cut with an NC machine in a room controlled at 25 ° C (cutting blade: carbide slow-away tip, 1 piece 4-component dynamometer [KISTLER Co., Ltd.] The resistance force that the cutting blade receives from the blade feed direction when the blade is 16 mmφ, the rotation speed is 5,000 rpm, the feed rate is 3,000 mm / min, and the cutting depth is 3 mm. "9272 type" manufactured by amplifier, amplifier: "charge amplifier 5011 type" manufactured by KISTLER, and recorder: "WR7700" manufactured by Graphtec Co., Ltd.]. The smaller the value of the cutting resistance, the better the machinability.
(5) Impact strength (KJ / m ² ) [Evaluation of mechanical strength]
In accordance with JIS K6911, measurement was performed using an “Izod impact tester” manufactured by Toyo Seiki Seisakusho (no notch).

From the results of Table 1, it was found that the polyurethane resin molded product for water-equivalent phantom material of the present invention has higher water equivalence and good physical properties compared to the comparative product.
In particular, in the comparison between Example and Comparative Example 1 (commercially available water equivalent epoxy resin), it was confirmed that water equivalence was high, Shore D hardness / impact strength was high, and flexural modulus was low.
This indicates that the mechanical strength and flexibility are excellent, and the properties are high in strength, but are less likely to cause “chip” and “crack”. Furthermore, the cutting resistance, which is an index of the machinability, is low, indicating that the machinability is good.

The polyurethane resin (Q) for water-equivalent phantom material and the polyurethane resin molded product (Z) for water-equivalent phantom material of the present invention are highly equivalent to the reference structure (water), and are not damaged during cutting and handling. Because it has few cracks, has good machinability, and is easy to handle, it can be widely used as a water-equivalent material in the field of radiation medicine such as particle beam therapy, radiation therapy, CT imaging, and nuclear medicine. .

Claims (5)

Polyurethane resin which is a reaction product of a polyurethane resin-forming composition containing polyol (a) and polyisocyanate (b) , inorganic filler (d) and organic filler (c) composed only of elements having atomic numbers 1 to 40 And (d) is a hydroxide, oxide, peroxide, carbonized product, carbonate of at least one element selected from the group consisting of magnesium, aluminum, and silicon. , Nitrates, sulfates, chlorides or silicates based on the total weight of (a), (b), (c) and (d), with each content (a) being 30-65%, ( b) is 15 to 45%, (c) is 5 to 50%, (d) is 1 to 30%, and the effective atomic number (n) obtained by the following formula (1) is 7.0 to 8. Radiation medical water equivalent phantom is zero Material polyurethane resin composition (Q).

[In Formula (1), (t) is a coefficient (3.5), (fi) is the ratio of the number of electrons of the i-th atom in the atoms constituting the resin to the number of electrons of the whole atoms constituting the resin. , (Zi) is the atomic number of the i-th atom among the atoms constituting the resin. ] (C) is a polyolefin resin particles according to claim 1 radiology water equivalent phantom material for a polyurethane resin composition. A polyurethane resin composition molded product (Z) for a water-equivalent phantom material for radiation medical use, which is a molded product of the polyurethane resin composition (Q) according to claim 1 or 2 . Density, according to claim 3, wherein the radiology water equivalent phantom material for a polyurethane resin composition molded article is 0.95~1.05g / cm ^3. The polyurethane resin composition molded article for a radiological water equivalent phantom material according to claim 3 or 4 , wherein the hardness measured by a type D durometer is 40 to 90.