JPS6198765A - Curable polyorganosiloxane composition having gamma ray shielding ability - Google Patents

Abstract

PURPOSE:The titled composition having improved toxic problems of lead, and gamma-ray shielding properties, comprising vinyl group-containing polyorganosiloxanes of specific combination and blending them with lead powder previously. CONSTITUTION:(A) 100 pts. wt. polyorganosiloxane shown by the formula I (R is monofunctional hydrocarbon containing no aliphatic unsaturated bond; R' is monofunctional hydrocarbon; n is number to make the component A have 100-50,000 cst viscosity) having both end groups hindered with vinyl groups is blended with (B) 10-100 pts. wt. polyorganosiloxane consisting of (R)2SiO unit and/or (R'')3SiO0.5 and SiO2 unit, wherein 2.5-10 mol % silicon atom. has vinyl group directly bonded to it. and (R'')-3SiO0.5:SiO2=0.4:1-1:1, (C) a polyorganohydrogen siloxane shown by the formula II (m>=2; a is 1-2; b is 0.1-1, etc.), (D) 600-2,000 pts. wt. based on 100 pts. wt. A+B+C of lead pow der, and (F) a platinum catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a cold-curable polyorganosiloxaf composition having a 7M shielding capacity.

[Prior Art] Conventionally, a gamma ray shielding material in which silicone Hl rubber is filled with lead powder is known. Conventional gamma-ray shielding materials were used by adding lead powder to the mixture on-site when compounding a two-component silicone rubber solution and pouring it into the area where gamma-ray shielding was required. However, lead powder is toxic, and handling it directly, especially in an open state, is undesirable due to health concerns.

In addition, since lead powder is easily oxidized in the air, it causes agglomeration due to oxidation during storage, which adversely affects workability and the physical properties of the cured product.Furthermore, conventionally used silicone rubber does not contain fillers such as silica. Therefore, in conventional shielding materials using such silicone rubber compositions, there is a limit to the amount of lead powder that can be blended, and the content of lead powder per unit volume is comparatively low. Therefore, a thick shielding material was required to obtain the necessary 7-wire shielding ability.

[Problem to be solved by the invention, α1 As mentioned above, the conventional 7m shielding material causes lead contamination at the construction site due to direct handling of lead powder at the construction site and health problems associated with it. Because the amount of lead powder required per volume was large, thick gamma-ray shielding material was required.

[Means for Solving Problem α] In order to solve the above problems, the present inventors have developed a silicone rubber composition having a special combination of vinyl group-containing polyorganosiloxane as a base polymer. The necessary strength can be obtained without adding fillers such as silicone rubber, and by adding lead powder as a component of silicone rubber in a sealed container in advance, it is possible to obtain lead directly in an open system such as a construction site. Eliminates the metal coming into contact with the powder.

That is, the present invention is based on the general formula (A) (where R is a monovalent hydrocarbon group containing no aliphatic unsaturated bond, R' is a monovalent hydrocarbon group, and 0 is the viscosity of (A) at 25°C).
)
2,100 parts by weight of polyorganosiloxa having an IT chain at both ends with a vinyl group represented by °.

(B): (R''' Contains or does not contain hsiO units,
(R”)2sio,,, unit and 5ift unit (in the formula “
represents a group selected from a monovalent hydrocarbon group containing no aliphatic unsaturated bond and a vinyl group), and 2.5 to 10 mol% of the silicon atoms have a vinyl group directly bonded to the silicon atom, (R'>5sioo, 10 to 100 parts by weight of a polyorinosiloxane copolymer having a ratio of s units: 5i02 units of 0.4:1 to 1:1, (C) 2 general formula (wherein R is ( In A), it is the same range as R, and l is 2
or more, a has a value of 1.0 to 2.0, b has a value of 0.1 to 1.0, and (i+b) has a value of 1.9 to 3.
0 and has an average of at least two hydrogen atoms directly bonded to silicon atoms per molecule), and hydrogen atoms directly bonded to silicon atoms per vinyl group of the polyorganosiloxanes (A) and (B). A sufficient amount of polyorganohydrogensiloxane to have 0.5 to 5.0 atoms, (D): [(A) + (B) + (C) 1100 parts by weight of lead powder produced by melt spraying. 600~z
, ooo parts by weight, and (E): an effective amount of a platinum catalyst.

The composition of the present invention comprises (A) and V/or (B) and (C) and (
If D) and (E) do not coexist, they will not cure, so it is sufficient to store either of them in separate packages and mix them just before use. For example, if the first package contains the entire amount of (D) and(
Most of A) and (/(B), the second packaging contains only (C) or the entire amount of (C) and a portion of (A) and V<8>, the third packaging contains the entire amount of (E) and (A ) and the remainder of CB), and the packaging of the three above can be mixed and cured at the time of use.

In the present invention, the monovalent hydrocarbon group represented by R1 (/R') of the vinyl chain end polyol ff/siloxane component (A) is preferably a furkyl group (e.g., methyl, ethyl, propyl, butyl, hexyl, octyl, and decyl group). ,
Aryl groups (e.g. phenyl, tolyl and xylyl groups)
, cycloalkyl groups (e.g. cyclohexyl and cycloheptyl groups), aralkyl groups (e.g. pennol, β-phenylethyl and β-phenylpropyl groups), and R' is further exemplified by alkenyl groups (vinyl and furyl groups). will be added. R and R' are each i
f! However, two or more types may be used in combination, and they may be the same or different from each other.

At least 50% of the groups represented by R and R' are selected from the group consisting of methyl and phenyl, and in particular preferred compositions all of the groups represented by R and R' are methyl and phenyl groups.

The value of n is determined when the viscosity of component (A) at 25°C is 100-
50,000 cSt, preferably 500-20. OOO
'cSt. The viscosity of component (A) is 100
If it is less than cSt, sufficient physical properties cannot be obtained, and 50,00
If it exceeds 0 cSt, handling in an uncured state becomes difficult.

The polyorganosiloxane copolymer as component (B) in the present invention is a component that provides sufficient strength to the composition without containing a reinforcing filler, and is a monovalent carbonized copolymer that does not contain aliphatic unsaturated bonds. It may be defined as a polyorga/siloxane copolymer containing R' groups, which can be hydrogen or vinyl groups, and in which a minor (both the aforementioned proportions) of R# groups are vinyl groups.

The R# groups that are not vinyl groups are those in the same range as the R groups of component (A) and similar groups, and in a preferred embodiment thereof, all of the monovalent hydrocarbon groups that do not contain aliphatic unsaturation are methyl groups. It is. The vinyl group is (R#)ssiOo,s
or (R-)2si as part of the group.

It can be present as part of the group or both.

Various siloxane units in the copolymer component (B) are (R
#) isiOo, s unit: ratio of 5iOz unit is 0.4
:1 or 1:1. (R')3S
If the ratio of iO0,, units is less than 0.4, the stability of component (B) will be poor and it will be difficult to synthesize it well, and if it exceeds 1, the cured product will have good fi?1 strength and overall Can't be strong.

(R'), the SiO units are present in an amount equal to O to 10 mole percent, based on the total number of siloxane units in the copolymer. Regardless of where the silicon-bonded vinyl groups are located in the copolymer, the silicon-bonded vinyl groups should be attached to 2.5 to 1000 mole percent of the silicon atoms of copolymer component (B). be.

Copolymer component (B) is a solid, at-fatty material, often prepared as a solution in a solvent such as xylene or toluene, and generally from 30 to 75% bone dissolution. . , I! 1. To facilitate the handling of the product,
This solution of copolymer component (B) is usually dissolved in part or all of the vinyl chain-terminated polysiloxane component (A), and the solvent is distilled off from the resulting solution to form the copolymer with component (A). component(
Make a mixture of B).

The amount of component (B) is 1 per 100 parts by weight of component (A).
0 to 100 parts by weight, preferably 20 to 80 parts by weight.

If the amount of component (B) is less than 10 parts by weight, sufficient mechanical properties cannot be obtained unless a reinforcing filler is blended, and it is intended in the present invention to blend a reinforcing filler in an amount that satisfies the mechanical properties. It becomes impossible to fill with lead necessary for shielding 7 wires. Also,
The amount of component (B) is 100 weight 1lff! If it exceeds +, the viscosity of the uncured composition becomes high, making it difficult to handle.

The polyol If/hydrogen siloxane of component (C) in the present invention reacts with components (A) and (B) to implant a network polysiloxane, and therefore has an average of at least two silicon bonds in the molecule. It has hydrogen atoms.

Such a polyorgan/hydrogen siloxane may have a chain, branched, or cyclic siloxane skeleton, and may be a polymer consisting only of siloxane units having silicon-hydrogen bonds, as well as triorgafsiloxy units, Noorganosiloxy units, monoorganosiloxy units and 5iO
1 out of y units! Alternatively, it may be a copolymer of two or more types. Examples of R include those similar to R in component (8), and it is acceptable to use one type or a combination of 2111 or more, but it may be easier to synthesize. Methyl and phenyl groups are preferred, with methyl groups being particularly preferred, since they provide relatively low viscosities and good physical properties after curing, and methyl groups are preferred, as they have an average of at least two silicon-bonded hydrogen atoms in the molecule. For ease of synthesis, ■ must be 2 or more, preferably in the range of 4 to i, ooo. When m is less than 4, volatility is high, and when m exceeds 1,000, synthesis and handling become difficult. Those where a is less than 1.0 or b is 1.0
It is difficult to synthesize anything exceeding this value. When a exceeds 2.0, the desired m cannot be obtained while component (C) has the necessary silicon-bonded hydrogen atoms, and when b is less than 0.1, the desired silicon-bonded hydrogen atoms are obtained. The number of cormorants increases, making it difficult to handle component (C). If the sum of a+b is less than 1.9, it is difficult to synthesize with good control, and if it exceeds 3.0, the required degree of polymerization cannot be obtained.

The amount of component (C) is such that the amount of hydrogen atoms directly bonded to silicon atoms contained in component (C) is 0.5 to 5.5% per vinyl group contained in components (A) and (B). This is enough to make the total number 0. If the number is less than 0.5, a rubber-like elastic body cannot be obtained, and if it exceeds 5.0, foaming may occur or the mechanical properties may deteriorate.

Component (D) used in the present invention is lead powder produced by melt spraying. The average particle size is preferably 1μ to 0.
51, more preferably 100 meshes (147μ)
It is a complete document. Lead powder of less than 1 μm is difficult to leave behind, and its surface is easily oxidized and its state changes easily. 0.5
If it exceeds 11+a, the sedimentation rate during mixing will be high and the strength of the composition after curing will be low.

The amount of component (D) is in the range of 600 to 2,000 parts by weight, preferably 800 to 1.50 parts by weight, based on 100 parts by weight of the total amount of components (A), (8), and (C). It is. 6
If it is less than 0.00 parts by weight, a sufficient gamma ray shielding effect cannot be obtained;
,000 parts by weight, component (A) (B) + (D
) becomes difficult to knead with 1. This makes on-site injection work difficult and reduces the strength of the cured composition.

The platinum catalyst acids q(E) used in the present invention include all known platinum catalysts that are effective in effecting the reaction between silicon dihydrogen bonds and silicon-bonded vinyl groups.

Examples of component (E) include platinum black, white chloride, gold acid, platinum-olefin complexes, platinum-vinylsiloxane complexes, platinum-phosphine complexes, platinum-phosphite complexes, and platinum alflate. Regardless of the aM of the platinum catalyst used, the catalyst is usually used in an amount sufficient to provide 10-3 to 10-G gram atoms of platinum per mole of silicon-bonded vinyl groups in the composition.

[Example 1] Hereinafter, the present invention will be explained based on Examples. In the examples, all parts are by weight. In the examples, Me represents a methyl group and Vi represents a vinyl group.

Example 1 Viscosity at 25°C is 3.000 cSt, with vinyl groups at both ends! 65 parts of chained polymethylsiloxane, 60 mol% Sin, 37.2 mol% Mes
SiOo, s units and 2.8 mol% MeViSi
70 parts of a 50% toluene solution of a copolymer consisting of O units was mixed and the mixture was gradually reduced in pressure and heated to 80° C. at 100 mmHg to distill off the toluene to obtain a vinyl group-containing polyol lf/siloxane mixture. This mixture was charged into a closed Nigu, and the average particle size obtained by melt spraying was 200 mesh (74μ) (average particle size 17μ).
1,000 parts of lead powder (1,000 parts) was added and mixed under closed conditions until uniform.

To this, Ne1SiO[Me2SiO]a[MellSi
O]4 # 5 parts of SiMei and chloroplatinic acid and 2-
50/1 million parts of a heated product of ethylhexyl/hexyl in terms of platinum atoms were added and mixed to obtain the composition of the present invention. This composition was defoamed, cast into a mold with a thickness of 130 mm, and left to stand at 30° C. for 24 hours to obtain a rubber-like cured product according to the present invention. The specific gravity of this cured product was 5.4.

This rubber-like cured product (sample) was placed in the measuring device shown in Figure 1, and γ-rays from 60CO were applied in the thickness direction to measure the amount of transmission.6 Similar measurements were performed on concrete samples of the same size, and γ- When the amount of radiation transmitted was compared, the amount of gamma ray transmitted through the rubber-like cured product according to the present invention was 44% of that of the concrete sample.

Example 2 255 parts of a polyorganosiloxa having a viscosity of 4,500 cSt at 25°C, both ends capped with vinyl groups, and consisting of -6 mol% nophenyl siaxane units and the remainder trimethylsiloxy units, and 52.5 parts 5iOz unit of mole %,
44.5 mol% Ne1SiO units and 3.0 mol%
90 parts of a 50% toluene solution of a copolymer consisting of MeViSiO units was mixed and desoluted in the same manner as in Example 1 to obtain a vinyl group-containing polyol/siloxane mixture. This mixture was placed in a closed type Nigu, and 900 parts of lead powder having an average particle diameter of 100 mesh (147 μm) obtained by melt spraying was added thereto and mixed in a closed state until uniform.

To this [M@2SiO←→MeHSiO]s 7
．． 5 parts and.

The same platinum catalyst used in Example 1 was used as a platinum atom.
A composition of the present invention was obtained by mixing 0/1 million parts.

This was defoamed and cast into the same mold as in Example 1, and left at 50°C for 6 hours to obtain a rubber-like cured product with a specific gravity of 5.1. When the gamma ray transmission amount of this rubber-like cured product was measured in the same manner as in Example 1, it was 47% of that of the concrete sample.

Example 3 A 50% toluene solution of the same copolymer as used in Example 1 and 60 parts of polymethylsiloxane, which had a viscosity of 2+000 cSt at 25°C and was capped with vinyl groups at both ends, was added.
0 part was desoluted in the same manner as in Example 1 to obtain a mixture of vinyl group-containing polyol and nonoloxane.

1.100 parts of the same lead powder as used in Example 1 was mixed with this in a sealed Nigu, and the mixture was sealed in a metal can to obtain a packaged sample.

Next, polydimethylsiloxane 10, which has a viscosity of 3.50.0 cSt at 25°C and is blocked at both ends with vinyl groups, is prepared.
0 parts and 100 parts of the same polymethylhydrogensiloxane used in Example 1 were mixed and sealed in a glass bottle to obtain a packaged sample B.

In addition, 500/100,000 parts of platinum-tetramethyltetravinylsynlotitrasiloxane complex as platinum atoms were mixed with 1001m of polydimethyl and siloxane in which both terminals were filMed with vinyl groups. A packaged sample C was obtained by sealing it in a glass bottle. These packaging samples ^,
After storing B and C at room temperature for one month after their respective preparations, they were mixed at a weight ratio of ^:B:C=100:10:10, defoamed, and cast in the same manner as in Example 1. 24 at 30℃
By standing for a period of time, a rubber-like cured product with a specific gravity of 5.2 was obtained.

When the gamma ray transmission amount of this rubber-like cured product was measured in the same manner as in Example 1, it was 46% of that of the concrete sample.

Example 4 70 parts of the same polymethylsiloxane end-capped with vinyl groups as used in Example 1 and 50 parts of the same branched polyol as used in Example 1 were added.
A packaging sample was obtained from 60 parts of the % toluene solution and 1,000 parts of the same lead powder used in Example 2 in the same manner as the packaging sample of Example 3.

Polydimethylsiloxane 10, which has a viscosity of 10.000 cSt at 25°C and is capped at both ends with vinyl groups, is used for dogs.
0ffll was mixed with 100 parts of the same polymethylhydrogensiloxane as used in Example 2 and sealed in a glass bottle.
Packaging sample E was obtained.

Further, 300/1 million parts of a platinum-triphenyl phosphite complex was mixed with platinum atoms in polydimethylsiloxane, which was used in Example 1 and whose ends were blocked with vinyl groups, and the mixture was sealed in another glass bottle. , packaging sample F was obtained.

After preparing each of these packaging samples, E and F,
After being stored at room temperature for a month, the weight ratio is D:E:F=100.
:1G:10, defoamed, cast in the same manner as in Example 1, and left at 50° C. for 6 hours to obtain a rubber-like cured product with a specific gravity of 5.0.

When the 7-line transmission amount of this rubber-like cured product was measured in the same manner as in Example 1, it was 48% of that of the concrete sample.

Example 5 63 parts and 55 mol of a polyorganosiloxaf having a viscosity of 6.0 OQcSL at 20°C, having vinyl groups at both ends and consisting of 5 mol% methylvinylsiloxy units and the remainder trimethylsiloxy units. % SiO□ unit, 41
．． 50% of a copolymer consisting of 5 mol% Me)SiOo, s units and 3.5 mol% HeViSiOo, units.
% toluene solution were mixed and removed in the same manner as in Example 1 to obtain a vinyl group-containing polyorganosiloxane mixture. This mixture and the same parts of lead powder i and ooo as used in Example 1 were charged and mixed in a sealed state until uniform.

To this, MesSi[MeH3iO]+, SiMe, 4
．． 5ff5 and the same platinum catalyst used in Example 3 were added and mixed in 100/1 million parts as platinum atoms to obtain a composition of the present invention.

This was poured into the same mold as in Example 1 and left at 50° C. for 6 hours to obtain a rubber-like cured product with a ratio of m5.4.

When the gamma ray transmission amount of this rubber-like cured product was measured in the same manner as in Example 1, it was 44% of that of the concrete sample.

[Effects of the Invention] According to the present invention, the problem of lead toxicity is solved because there is no direct contact with lead powder at an open construction site.

In addition, lead fine powder is easily oxidized, but by supplying it mixed with silicone as in the present invention, lead oxidation and accompanying particle aggregation can be prevented during storage, improving workability and physical properties of cured products. can be kept. Furthermore, since the amount of lead added is significantly increased, a high-density shielding material with a specific gravity of 5 or more, which has not been obtained conventionally, can be obtained, and it can be used as a shielding material with excellent gamma ray shielding properties.

[Brief explanation of drawings]

The figure is a schematic cross-sectional view of a device that defines the gamma ray shielding effect of a shielding material. In the figure: 1...'. Col1 source, 2... Lead shielding wall, 3...
Sample, 4...M quantity meter, 5...Chain containing the sample 6-, A...Distance between radiation source and #a quantity meter (800 mml,
Mouth...60co source side lead shielding wall thickness 150 copies)
, ha... the back of the chamber ff! (250+am), 2... #i meter side lead shielding wall thickness 10100v, to...
... γ-ray passage (diameter 20au*), e...sample thickness 1301). Patent Applicant: Toshiba Silicone Co., Ltd. Patent Applicant: Asahi Asbestos Industries Co., Ltd. (No change in the contents of the drawing) Procedural Amendment (Method) December 2, 1985

Claims (1)

[Claims] 1. (A): General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R is a monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, and R' is a monovalent hydrocarbon group. group, n is the viscosity of (A) 25°C
(indicates the number of 100 to 50,000 cSt)
100 parts by weight of polyorganosiloxane with both ends capped with vinyl groups represented by (B): (R″)_2 Containing or not containing SiO units, (
R″)_3SiO_0_._5 units and SiO_2 units (
In the formula, R'' represents a group selected from a monovalent hydrocarbon group containing no aliphatic unsaturated bond and a vinyl group), and 2.5 to 10 mol% of the silicon atoms are vinyl groups directly bonded to the silicon atom. and (R″)_3SiO_0_. _5 units:
10 to 100 parts by weight of a polyorganosiloxane copolymer with a ratio of SiO_2 units of 0.4:1 to 1:1, (C): General formula {(R)_a(H)_bSiO_[_(_4_-_a_
−_b_)_/_2_]}_m (in the formula, R is in the same range as R in (A), m is a number of 2 or more, and a is 1
．． has a value of 0 to 2.0, b has a value of 0.1 to 1.0, (a+b) has a value of 1.9 to 3.0, and an average of at least 2 silicon atoms per molecule. having a hydrogen atom directly bonded to), and sufficient hydrogen atoms to have 0.5 to 5.0 hydrogen atoms directly bonded to a silicon atom for each vinyl group of the polyorganosiloxanes (A) and (B). 600 to 2,000 parts by weight of lead powder produced by melt spraying per 100 parts by weight of polyorganohydrogensiloxane (D): [(A) + (B) + (C)]
A curable polyorganosiloxane composition having gamma ray shielding ability, comprising: parts by weight, and (E): an effective amount of a platinum catalyst. 2. The first package contains the entire amount of (D) and most of (A) and (B), the second package contains only (C) or the entire amount of (C) and a portion of (A) and (B), and the third package A curable polyorganosiloxane composition having gamma ray-shielding ability according to claim 1, wherein the package consists of the entire amount of (E) and the balance of (A) and (B). 3. The curable polyorganosiloxane composition having gamma ray shielding ability according to claim 1, wherein at least 50 mol% of R, R', and R'' are methyl groups. 4, R, R', 2. The curable polyorganosiloxane composition having gamma ray-shielding ability according to claim 1, wherein R'' and R'' are a methyl group and a vinyl group. 5. The viscosity of (A) is 500 to 20,00 at 25°C
The curable polyorganosiloxane composition having gamma ray shielding ability according to claim 1, which has a gamma ray shielding ability of 0 cSt. 6. The curable polyorganosiloxane composition having gamma ray shielding ability according to claim 1, wherein the amount of (B) is 20 to 80 parts by weight. 7. The curable polyorganosiloxane composition having gamma ray shielding ability according to claim 1, wherein m is 4 to 1,000. 8. Curable material having gamma ray shielding ability according to claim 1, wherein the amount of lead powder is 800 to 1,500 parts by weight per 100 parts by weight of [(A) + (B) + (C)]. Polyorganosiloxane composition. 9. The curable polyorganosiloxane composition having gamma ray shielding ability according to claim 1, wherein the lead powder has a particle size of 1 μm to 0.5 mm.