JPH0245566A - Room temperature-curing silicone rubber impression material composition - Google Patents

Abstract

PURPOSE:To provide a room temperature-curing silicone rubber impression material composition composed of a polyorganosiloxane, a polyorganohydrogensiloxane, fine powder of a specific water-absorbing polymer component and a platinum catalyst and having high wettability. CONSTITUTION:The objective composition contains (A) 100 pts.wt. of a polyorganosiloxane having two or more units of formula I (R<1> is alkenyl; R<2> is univalent hydrocarbon group free from aliphatic unsaturated bond; a is 1 or 2; b is 0, 1 or 2; a+b is 1-3), (B) a plyorganohydrogensiloxane expressed by formula II (R<3> is univalent hydrocarbon group; c is 0-2; d is 1 or 2; c+d is 1-3) and having >=3 Si bonds in an amount to give 0.5-4 Si-bonded H atoms per one R<1> group of the component A, (C) 0.01-5 pts.wt. of fine powder of a water-absorbing polymer component containing acrylic acid (metal salt) or maleic acid unit and (D) 1-100ppm (based on the component A) of a platinum catalyst for addition reaction.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a room-temperature-curable silicone rubber impression material composition, and more particularly to a room-temperature-curable silicone rubber impression material composition that has high wettability with water. .

[Technical background of the invention and its problems 1 Silicone rubber made from polyorganosiloxane is widely used as a variety of molding materials, ie, silicone rubber impression materials, due to its excellent mold release properties.

Examples of silicone rubber impression materials include condensed silicone rubber impression materials obtained by flowing polyorganosiloxane having hydroxyl groups at both ends of the molecular chain at room temperature using an alkyl silicate as a crosslinking agent. However, this condensation silicone rubber impression material suffers from large dimensional changes due to volatilization of alcohol, which is a by-product of the condensation reaction, and has the disadvantage that an alcohol odor remains.

In order to overcome the drawbacks of condensation type silicone rubber impression materials, an addition reaction type material has been developed in which a vinyl group-containing polyorganosiloxane and a polyorganohydrodiene siloxane are mixed together at room temperature using a platinum catalyst.

This addition reaction type silicone rubber impression material has the advantages that it has no reaction by-products, has a smaller linear shrinkage rate than the condensation type silicone rubber impression material, has high dimensional accuracy, is odorless, and has excellent workability. However, on the other hand, addition-reactive silicone rubber impression materials are excellent for making impressions on plastic molded products due to the unique hydrophobicity of silicone rubber. When applied as an intraoral dental impression material, it has the disadvantage of poor impression accuracy because it does not easily wet when it comes into contact with soft tissue or hard tissue plaque in the oral cavity.

We also use this addition reaction type silicone rubber impression material.

When molding plaster or the like using this method, voids may be formed on the surface adjacent to the impression mold due to its poor wettability with water, which has the disadvantage of reducing the impression quality.

As a method to solve these drawbacks of addition reaction type silicone rubber impression materials, a method has been proposed in which a silicone-polyether modified oil is added to addition reaction type silicone rubber (see JP-A-62-252706). . However, this technique has the drawback that the added silicone-polyether modified oil bleeds out from inside the addition type silicone rubber over time, resulting in a lack of sustained water wettability.

[Object of the Invention] The present inventors aim to solve the above-mentioned problems and provide a room-temperature curable silicone rubber impression material composition that has high wettability both when uncured and after curing. .

[Structure of the Invention] That is, the room temperature curable silicone impression material composition of the present invention has the following formula (A): (R1). (R2)ゎ5in4-0゜wa, (■)
(In the formula, R' represents an alkenyl group; R2 represents a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond; a represents 1 or 2; b represents O9 or 2; Table: a+b represents 1°2 or 3) Polyorganosiloxane having at least two structural units in one molecule, 100 parts by weight: (B) The following formula, (R3) c Ha S 10+-1c+al ( I
I) (wherein R3 represents a substituted or unsubstituted monovalent hydrocarbon group; 10 represents 0.1 or 2; d represents 1 or 2; c+d represents 1.2 or 3); A polyorganohydrodiene siloxane consisting of the structural units shown and having at least three hydrogen atoms bonded to silicon atoms in one molecule, for 11 groups R in the structural units represented by formula (I) of component (A) (C) A polymer or copolymer containing a structural unit based on acrylic acid, an alkali metal salt of acrylic acid, or maleic acid, or A finely powdered water-absorbing polymer component consisting of a mixture of these, 0.01 to 5 parts by weight, and (D) a platinum catalyst for addition reaction, 1 to 11 parts by weight based on component (A).
It is characterized by containing 00pp.

The polyorganosiloxane as component (A) used in the present invention has the formula (I) containing an alkenyl group bonded to a silicon atom.
) has at least two structural units in one molecule. As such polyorganosiloxane, either linear or branched polyorganosiloxane can be used,
It is also possible to use mixtures of these.

Examples of the group R1 in formula (I) include vinyl group, allyl group, ■-butenyl group, and ■-hexenyl group, but vinyl group is the most preferred from the viewpoint of ease of synthesis and thermal stability. It's advantageous.

In addition to group R2, group R1, and group R2, organic groups capable of bonding to a silicon atom include, for example, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group, and dodecyl group; aryl groups such as phenyl group; Group: β-
Examples include aralkyl groups such as phenylethyl group and β-phenylpropyl group, and further examples include substituted hydrocarbon groups such as chloromethyl group and 3,3,3-trifluoropropyl group. Among these groups, the methyl group is preferred as the group R2 because it is easy to synthesize, provides the degree of polymerization necessary to maintain good physical properties after curing, and provides low viscosity before curing. The most preferred structural unit represented by formula (I) may be present at either the end of the molecular chain or in the molecular chain of the polyorganosiloxane, but in order to impart excellent mechanical properties to the cured product, Preferably, it exists at at least one end of the molecular chain.

The polyorganosiloxane of component (A) preferably has a viscosity of 100 to 500.000 cP at 25°C.

Component (B) used in the present invention is polyorganohydrodiene siloxane, which must have at least three hydrogen atoms bonded to silicon atoms in one molecule in order to form a network through crosslinking. be. The above formula (II)
Examples of the group R3 in the group R3 and other organic groups capable of bonding to silicon atoms include the group R3 in the component (A) described above.
``, but from the viewpoint of easy synthesis, a methyl group is most preferred.

(B) component is 25% due to ease of synthesis and ease of handling.
Preferably, the viscosity at °C is 1 to 10.000 cP.

The polyorganohydrodiene siloxane may have a linear, branched or cyclic structure, or a mixture thereof may be used.

The blending amount of component (B) is 1 alkenyl group in component (A).
The number of hydrogen atoms bonded to silicon atoms in component (B) is 0.5 to 4. O1 preferably 1.0 to 3.0
The amount is such that If the number of hydrogen atoms is less than 0.5, curing of the composition will not proceed sufficiently and the hardness of the cured composition will be low; if the number of hydrogen atoms exceeds 4.0, The mechanical properties of the composition after curing are reduced.

Component (C) used in the present invention is a finely powdered water-absorbing polymer component consisting of a polymer or copolymer, or a mixture thereof, containing a structural unit based on acrylic acid, an alkali metal salt of acrylic acid, or maleic acid. .

Examples of the polymer or copolymer of component (C) include acrylic acid-vinyl alcohol copolymer, sodium acrylate polymer, sodium acrylate-acrylamide copolymer, Sumikagel 5P-520, NP-1020 (trade name, Sumitomo Chemical Industries (Kiyomi), Aqua Keep 45, l03H
(trade name, manufactured by Seitetsu Kagaku Kogyo ■).

Component (C) may be in any form such as spherical, powder, granular, or fibrous, but it exhibits high wettability to the composition and provides sufficient mechanical strength to the cured product. In order to apply it, it is preferably in powder form.

When a powdered polymer is used as component (C), it is preferably in the form of a fine powder with an average particle diameter of 0.1 to 200 μm. If the average particle size is less than 0.1 parts m, it will be difficult to uniformly disperse it in the composition;
If it exceeds the above range, it becomes more like a foreign substance and may lead to a decrease in the mechanical properties of the cured product, especially the rubber elasticity.

The blending ratio of component (C) is 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight, per 100 parts by weight of component (A). If the blending ratio is less than 0.01 part by weight,
Sufficient wettability cannot be obtained, and even if it is used in an amount exceeding 5 parts by weight, the effect is not increased, and the impression of the composition is rather reduced.

The platinum-based catalyst for the addition reaction of component (D) used in the present invention is:
This is a component that promotes the addition reaction between the alkenyl group in component (A) and the hydrosilyl group in component (B).

Examples of the platinum-based catalyst as component (D) include simple platinum, chloroplatinic acid, platinum coordination compounds such as platinum-olefin complexes, and platinum-alcohol complexes.

The blending amount of component (D) is 1 to 100 ppm as platinum atoms relative to component (A), preferably 2 to 50 ppm.
It is pm. If the blending amount is less than 1 ppm, the object of the present invention cannot be achieved;
Even if the curing speed exceeds that amount, no further improvement in curing speed can be achieved.

In addition to components (A) to (D), the composition of the present invention may optionally contain fillers such as diatomaceous earth, calcium carbonate, ground quartz, atomized silica; pigments such as red iron oxide, titanium dioxide, zinc white, Ultramarine blue etc. can be added. Furthermore, depending on the purpose, other polyorganosiloxanes may be used in combination within a range that does not impair the effects of the present invention.

[Effects of the Invention] The cured product of the composition of the present invention has high wettability regardless of the degree of curing, and can maintain the wettability for a long period of time.

The composition of the present invention is useful not only as a conventional impression material for plastic molding, but also as an impression material for areas covered with water, such as an impression material for intraoral dentistry.

[Example 1 of the Invention The present invention will be described in further detail below with reference to Examples and Comparative Examples. In addition, all "parts" in Examples and Comparative Examples represent "parts by weight."

Examples 1 to 5 100 parts of polydimethylsiloxane base oil having a viscosity of 1.000 cP at 25°C and having both ends of the molecular chain capped with dimethylvinylsilyl groups, Crystallite VX-5 (trade name, (manufactured by Tatsumori) 100 copies,
1.5 parts of a linear polydimethylhydrodiene siloxane with both ends capped with trimethylsilyl groups, a silicon-bonded hydrogen content of 0.8% by weight, and a viscosity of 20 cP at 25°C, chloroplatinic acid M in isopropyl alcohol (as platinum to base oil) 30
A composition of the present invention was obtained by mixing ppm J5 and Sumikagel 5P520 (trade name, manufactured by Sumitomo Chemical Industries, Ltd.) as a fine powder of acrylic acid-vinyl alcohol copolymer in the amounts shown in Table 1.

After this composition was cured at 30° C. into a 2 mm thick sheet, the contact angle was measured to evaluate wettability. The results are shown in Table 1.

Comparative Example 1 A composition having the same composition as in Examples 1 to 5 was obtained except that the acrylic acid-vinyl alcohol copolymer fine powder in Examples 1 to 5 was not used.

This composition was cured into a sheet in the same manner as in Examples 1 to 5, and the contact angle was measured. The results are shown in Table 1.

Table Examples 6 to 8 100 parts of a polydimethylsiloxane base oil whose viscosity at 25°C is 5.000 cP and which is capped with dimethylvinylsilyl groups at both ends, Aerosil 200 which is fumed silica (trade name, manufactured by Degussa ■) 10 copies, (CF(3)
) [(consisting of SiO group units and 5 i 02 units, containing 1.02% by weight of hydrogen atoms bonded to silicon atoms,
2 parts of polymethylhydrodiene siloxane with a viscosity of 20 cP at 25°C, 20 ppm of chloroplatinic acid (based on the base oil as platinum) and KI-Gel 201K (trade name, Clareisobrene Chemical) as a fine powder of maleic anhydride-isobutylene copolymer. A composition of the present invention was obtained by mixing the amounts shown in Table 2.

After this composition was cured at 50° C. into a 2 mm thick sheet, the contact angle (contact angle a) was measured. Further, after this sheet was left at 50°C for 60 days, the contact angle (contact angle b) was measured again. The results are shown in Table 2.

Comparative Example 2 A composition having the same composition as Examples 6 to 8 was obtained except that the maleic anhydride-isobutylene copolymer fine powder was not added.

Using this composition, a sheet-like cured rubber product was obtained in the same manner as in Examples 6 to 8, and the contact angle was measured.

The results are shown in Table 2.

Comparative Example 3 The same procedure as Examples 6 to 8 was carried out, except that the compound shown in Table 2 was used as silicone-boether modified oil in place of the maleic anhydride-isobutylene copolymer fine powder in Examples 6 to 8. A composition with the same composition was obtained.

Table 2 CH3CH3 Using this composition, a sheet-like cured rubber product was obtained in the same manner as in Examples 6 to 8, and the contact angle was measured.

The results are shown in Table 2.

Example 9 100 parts of a polydimethylsiloxane base oil with a viscosity of 10.000 cP at 25°C and blocked at both ends with dimethylvinylsilyl groups, Aerosil 200 (trade name,
20 parts (manufactured by Degutsusa ■), 3 parts of Sunwet IM-300 (trade name, manufactured by Sanyo Chemical Industries ■) as a starch-acrylic acid graft copolymer fine powder, and 60 ppm of chloroplatinic acid (as platinum based on the base oil) were uniformly added. A base compound A was prepared by dispersing the base compound in

Next, based on 100 parts of base compound A, a linear polyester having both ends capped with trimethylsilyl groups, having a silicon-bonded hydrogen content of 0.8% by weight, and a viscosity of 20 cSt at 25°C was added. Two parts of dimethylhydrogensiloxane were mixed to obtain the composition of the present invention.

After curing this composition into a 2 mm thick sheet at 20'C, the contact angle was measured and found to be 16 degrees.6 Furthermore, even if Base Compound A was left at 50°C for 60 days, the base compound There was no change in the appearance or properties of A. (This product was cured into a sheet in the same manner as above, and the contact angle with water was measured, and it was 16 degrees, the same as the initial value.

Claims (1)

[Claims] (1) (A) The following formula, (R^1)_a(R^2)_bSiO_4_-_(_a
____b_)_/_2(I) (In the formula, R^1 represents an alkenyl group; R^2 represents a substituted or unsubstituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond; a is 1 or 2; b is 0.1 or 2
a + b represents 1, 2 or 3) 100 parts by weight of a polyorganosiloxane having at least two structural units in one molecule; (B) The following formula, (R^3)_cH_dSiO_4_-_( ＿c＿＋＿d
_)_/_2(II) (wherein, R^3 represents a substituted or unsubstituted monovalent hydrocarbon group; c represents 0.1 or 2; d represents 1 or 2; c+d represents 1 , 2 or 3) and having at least three hydrogen atoms bonded to silicon atoms in one molecule, a polyorganohydrodiene siloxane having a composition represented by the formula (I) of component (A) An amount such that the number of hydrogen atoms bonded to silicon atoms is 0.5 to 4.0 per 11 groups in the unit; (C) Based on acrylic acid, an alkali metal salt of acrylic acid, or maleic acid. 0.01 to 5 parts by weight of a finely powdered water-absorbing polymer component consisting of a polymer or copolymer containing the structural unit, or a mixture thereof, and (D) a platinum catalyst for addition reaction, and component (A). Against 1-10
A room temperature curable silicone rubber impression material composition, characterized in that it contains 0 ppm.