JP2620424B2 - Room temperature curable silicone rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable silicone rubber composition, and more particularly to a room temperature curable silicone rubber composition suitable for dental impression materials.

[0002]

2. Description of the Related Art Addition-curable curable silicone compositions are widely used as impression materials. The curable silicone composition has excellent curability, has very small shrinkage during curing, and does not generate by-products. Further, the cured product has excellent dimensional stability, tasteless and odorless, and has excellent characteristics such as easy demolding.

[0003] However, since the conventional curable silicone composition is hydrophobic, if the surface from which the impression is taken is wet, the surface is not well adapted to the surface and it is difficult to obtain an accurate impression. there were. For example, when using as a dental impression material and taking a wet intraoral mold, it is difficult to obtain a precise impression in detail, and cast a gypsum mud on the obtained impression to make a model. Sometimes there was a problem with the wetting of the gypsum mud impression, making it difficult to obtain an accurate model.

Therefore, as a method of improving the wettability to gypsum mud, a method of imparting hydrophilicity by spraying a detergent solution onto the surface of the impression immediately before casting the gypsum mud has been attempted. Curable silicone compositions containing surfactants [Lacy, A., Treleaven, S. & Tendrese
n, M., Cal. Dent. Assn. J., 5, 36-40 (1977), Norli
ng, DK & Reisbick, MH, J. Pros. Dent., 42, 342
-347 (1979)] has also been proposed. Further, JP-A-62-25
Japanese Patent No. 2706 discloses a method of adding a silicone-modified polyether compound as a hydrophilicity-imparting agent to a silicone composition, and Japanese Patent Application Laid-Open No. 63-146805 discloses a method of adding a water-soluble or slightly water-soluble protein. It has been disclosed.

[0005] However, the modified polyether silicone compound has a problem that the silicone oil itself is inherently hydrophobic and thus easily decomposed, and the protein causes odor at the time of an oral impression and rots during long-term storage. Have. In addition, in the method of JP-A-63-130510 in which a nonionic surfactant is added in an amount of 1 to 10% by weight, a small amount is better in that it is difficult to separate. There is a drawback that the wettability at the time of flowing out and gypsum is reduced.

[0006]

An object of the present invention is to provide a room-temperature-curable silicone rubber composition which solves the above-mentioned problems and has high wettability both in an uncured state and in a cured state. Aim.

[0007]

The present invention provides a room-temperature-curable silicone rubber composition comprising the following components (A), (B), (C), (D) and (E). is there. (A) Formula (I): (R ¹ ) _a (R ² ) _b SiO _{[4- (a + b)] / 2} (I) (wherein, R ¹ represents an alkenyl group, and R ² represents an aliphatic group. Represents a substituted or unsubstituted monovalent hydrocarbon group containing no unsaturated bond, a represents 1 or 2, b represents 0, 1 or 2,
And a + b is 1, 2 or 3) in one molecule. (B) Formula (II): (R ³ ) _c H _d SiO _{[4- (c + d)] / 2} (II) (wherein, R ³ represents a substituted or unsubstituted monovalent hydrocarbon group) C represents O, 1 or 2, d represents 1 or 2, and c + d is 1, 2 or 3), and a hydrogen atom bonded to a silicon atom is contained in one molecule. A polyorganohydrogensiloxane having at least three polyorganohydrogens may be selected from the group consisting of R ¹ in the polyorganosiloxane of component (A).
An amount such that the amount of hydrogen atoms bonded to silicon atoms becomes 0.5 to 5.0 per one group. (C) A platinum-based catalyst is used in an amount of 1 to 100 ppm as platinum atoms with respect to component (A). (D) Formula (III): (R ⁴ ) _e (HO) _f SiO _{[4- (e + f)] / 2} (III) (wherein R ⁴ is a substitution not containing an aliphatic unsaturated bond) Or e represents an unsubstituted monovalent hydrocarbon group, e represents a number of 1.9 to 2.2, f represents a number of 0 to 0.1, and e + f represents 1.9 to 2.2. A))
Polydiorganosiloxane viscosity is more than 300,000cP at 25 ° C., component (A) 0.5 to 20 parts by weight per 100 parts by weight (E) Formula ^{(IV): R 5 -0- (} CH 2 CH 2 O) _n H (IV) (wherein, R ⁵ represents an alkyl group or an alkenyl group;
Represents an integer of from 2 to 15), wherein 3 to 40 parts by weight of an alkyl ether or alkenyl ether of polyoxyethylene represented by the formula (A) is added to 100 parts by weight of component (A).

Hereinafter, the present invention will be described in detail. The polyorganosiloxane of the component (A) used in the present invention has at least two structural units of the formula (I) containing an alkenyl group bonded to a silicon atom in one molecule. As such a polyorganosiloxane, any of a linear or branched or a mixture thereof can be used.

The alkenyl group of R ¹ in the above formula (I) includes, for example, vinyl, allyl, 1-butenyl, 1-
Hexenyl and the like can be mentioned, but a vinyl group is the most advantageous in view of easiness of synthesis and thermal stability.

The monovalent hydrocarbon group of R ² includes, for example, an alkyl group such as methyl, ethyl, propyl, butyl, hexyl and dodecyl; an aryl group such as phenyl;
-Phenylethyl, aralkyl groups such as β-phenylpropyl, and further, chloromethyl,
Examples include substituted hydrocarbon groups such as 3,3,3-trifluoropropyl. Of these, a methyl group is most preferable because it is easy to synthesize, gives a degree of polymerization necessary for maintaining good physical properties after curing, and gives a low viscosity before curing.

The structural unit represented by the formula (I) may be present at the terminal of the molecular chain or in the molecular chain of the polyorganosiloxane. However, in order to impart excellent mechanical properties to the cured product, It is preferably present at at least one molecular chain terminal.

The viscosity at 25 ° C. of the polyorganosiloxane (A) used in the present invention is 100 to 500,000.
It is preferably 0 cP.

The polyorganohydrogensiloxane of the component (B) used in the present invention has at least three hydrogen atoms bonded to silicon atoms in one molecule in order to crosslink the composition by crosslinking. is required. R ³ in the above formula (II) is the same group as R ² in the above formula (I), but is most preferably a methyl group from the viewpoint of easy synthesis.

Component (B) preferably has a viscosity at 25 ° C. of 1 to 10,000 cP in view of ease of synthesis and ease of handling.

As the polyorganohydrogensiloxane (B), any of linear, branched and cyclic structures can be used, and a mixture thereof can also be used.

Component (B) is compounded in an amount of 0.5 to 5.0 hydrogen atoms bonded to silicon atoms in component (B), preferably one alkenyl group in component (A). 1.0
The amount is such that it is up to 4.0. When the number of hydrogen atoms is less than 0.5, curing of the composition does not proceed sufficiently,
The hardness of the composition after curing is low, and when the number of hydrogen atoms exceeds 5.0, the mechanical properties of the composition after curing deteriorates.

The platinum catalyst of the component (C) used in the present invention is a component for accelerating the addition reaction between the alkenyl group in the component (A) and the hydrosilyl group in the component (B).
Examples of such a platinum-based catalyst include platinum alone, chloroplatinic acid, and a platinum coordination compound such as a platinum-olefin complex or a platinum-alcohol complex.

Component (C) is used in an amount of 1 to 100 ppm, preferably 2 ppm, as platinum atoms with respect to component (A).
~ 50 ppm. If the amount is less than 1 ppm, the object of the present invention cannot be achieved, and if it exceeds 100 ppm, no further improvement in the curing speed can be achieved.

The component (D) used in the present invention is a component characteristic of the present invention, which can impart stable release properties and hydrophilicity when used together with the component (E).

R ⁴ in the formula (III) in the polydiorganosiloxane of the component (D) is the same group as R ² in the above-mentioned formula (I). Is excellent, 50% by weight or more of these are preferably methyl groups, and more preferably all are methyl groups.

The meanings of e, f and e + f in the formula (III) are as described above. However, when a large number of hydroxyl groups are present in the molecule, f is 0 because the releasability of the cured product decreases. Is more preferable, and most preferably substantially zero.
When the value of e + f is less than 1.9, workability is poor,
If it exceeds 2.2, the molecular weight is lowered, which is not preferable.

The viscosity of this component (D) at 25 ° C. is 3
It is more than 00,000 cP. This viscosity is 300,000
If it is less than cP, the releasability effect due to the combined use with the component (E) decreases. The amount of component (D) is 0.5 to 20 parts by weight based on 100 parts by weight of component (A). If the amount is less than 0.5 part by weight, there is no ability to retain the surfactant, and if the amount exceeds 20 parts by weight, the viscosity of the composition becomes extremely high, which is not suitable.

The alkyl ether or alkenyl ether of the polyoxyethylene of the component (E) used in the present invention is
It is a nonionic surfactant having a polyether as a hydrophilic group as shown by the formula (IV).

When the component (E) is used in combination with the component (D), it can impart hydrophilicity, not only has good wettability upon curing in the oral cavity, but also has a good property when cast into water after washing with water. There is an excellent advantage that a decrease in wettability is small.

R ⁵ in the above formula (IV) is an alkyl group or an alkenyl group and is usually lauryl, cetyl, stearyl or oleyl. N is 2 in terms of compatibility with the siloxane polymer in the silicone rubber composition.
To 15, particularly preferably 4 to 10.

The amount of component (E) is 100 parts (A)
It is 3 to 40 parts by weight, preferably 5 to 30 parts by weight based on parts by weight. If the amount is less than 3 parts by weight, the effect of the hydrophilicity of the nonionic surfactant during washing with water is small.

The composition of the present invention may optionally contain a reinforcing agent such as an inorganic filler. Examples of such an inorganic filler include fumed silica, precipitated silica, fused silica, quartz fine powder, diatomaceous earth, alumina, aluminum silicate, iron oxide, titanium oxide, zinc oxide, calcium carbonate , and carbon black. And one or more of these can be used. In addition, these inorganic fillers may be provided on the surface thereof with polyorganosiloxanes such as polydimethylsiloxane and octamethylcyclotetrasiloxane as required; hexamethyldisilazane, 1,1,3,3-tetramethyl-1, 3
Those treated with an organosilicon compound such as a silazane such as divinyldisilazane; or an organosilane such as vinyltriethoxysilane.

The mixing ratio of the inorganic filler is not particularly limited, but is preferably 5 to 200 parts by weight, more preferably 10 to 100 parts by weight, per 100 parts by weight of the component (A). is there.

The composition of the present invention can be finally produced by mixing the above five components (A) to (E) so as to be uniform. The specific procedure in this case is not particularly limited, but it is usually preferable to mix the component (D) with the component (A), disperse as uniformly as possible, add the other components, and mix. . This is because the curing reaction starts immediately when the components (A), (B) and (C) coexist. Therefore, component (A)
It is preferable that component (B) and component (C) coexist immediately before use in the oral cavity. In this case, an addition reaction retarder such as an acetylene-based compound, an olefin-based compound, an organic nitrogen compound, or an organic phosphorus compound may be added to the composition to suppress the curing reaction.
Further, depending on the purpose, other polyorganosiloxanes can be used in combination as long as the effects of the present invention are not impaired.

[0030]

According to the present invention, the room-temperature-curable silicone rubber composition of the present invention can be cured at room temperature in a short time, for example, about several minutes by mixing the components at the time of use. Even during and after curing, the composition of the present invention has hydrophilicity, and has good wettability to a hydrophilic substance or a water-containing substance. Therefore, an accurate impression can be obtained even when used in a humid atmosphere in the oral cavity, and it is particularly suitable as a dental impression material. Further, it can be widely used for molding materials requiring hydrophilicity or other uses.

[0031]

The present invention will be described below in more detail with reference to examples and comparative examples. In the following, all “parts” represent “parts by weight”. All physical property values such as viscosity are values at 25 ° C.

Example 1 and Comparative Examples 1-2 Polydimethylsiloxane having a viscosity of 2,000 cP and having both ends blocked with vinyl groups, methylhydrogensiloxane having a viscosity of 80 cP (containing 0.3% by weight of SiH groups), chloride Platinic acid octanol complex (containing 0.4% by weight of platinum), fumed silica, quartz fine powder and calcium carbonate were blended according to the composition shown in Table 1. As Example 1, both ends of the raw rubber were blocked with trimethylsilyl groups. A room temperature curable paste-like silicone rubber composition containing polydimethylsiloxane (degree of polymerization: about 7,000) and polyoxyethylene oleyl ether having a viscosity of 70 cP was prepared.

Further, the compositions of Comparative Example 1 in which no polyoxyethylene oleyl ether was blended and Comparative Example 2 in which no polydimethylsiloxane was blended were also prepared.

These paste compositions were mixed and stirred, sandwiched between glass plates with 6 mm spacers inserted, and cured for 10 minutes. One drop of distilled water was dropped on the surface of the obtained cured product, and after 30 seconds and 5 minutes, the contact angle between the water droplet and the surface of the cured product was measured using a contact angle meter (manufactured by Kyowa Science Co., Ltd.). Table 1 shows the results.

[0035]

[Table 1]

Examples 2 to 4 and Comparative Examples 3 to 5 The same procedures as in Example 1 were carried out except that the polyoxyethylene oleyl ether shown in Table 2 was used in the amounts shown in the same table. -4 and Comparative Examples 3-5 were prepared and cured in the same manner as in Example 1.

The cured product obtained was immersed in tap water for 10 minutes and washed with water, and the non-washed product was measured for contact angle.
Table 2 shows the results.

[0038]

[Table 2]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Reference number in the agency FI Technical indication (C08L 83/05 83:06 83:07 71:02)

Claims (1)

(57) [Claims] 1. The following components (A), (B), (C),
A room temperature curable silicone rubber composition comprising (D) and (E). (A) Formula (I): (R ¹ ) _a (R ² ) _b SiO _{[4- (a + b)] / 2} (I) (wherein, R ¹ represents an alkenyl group, and R ² represents an aliphatic group. Represents a substituted or unsubstituted monovalent hydrocarbon group containing no unsaturated bond, a represents 1 or 2, b represents 0, 1 or 2,
And a + b is 1, 2 or 3) polyorganosiloxane having at least two structural units per molecule (B) Formula (II): (R ³ ) _c H _d SiO _{[4- (c + d)] / 2} (II) (wherein, R ³ represents a substituted or unsubstituted monovalent hydrocarbon group. c represents O, 1 or 2, d represents 1 or 2, and c + d represents 1, 2, or 3), and having at least three hydrogen atoms bonded to silicon atoms in one molecule, a polyorganohydrogensiloxane represented by R in the polyorganosiloxane of component (A). ¹
An amount such that the amount of hydrogen atoms bonded to silicon atoms becomes 0.5 to 5.0 per one group. (C) A platinum-based catalyst is used in an amount of 1 to 100 ppm as platinum atoms with respect to component (A). (D) Formula (III): (R ⁴ ) _e (HO) _f SiO _{[4- (e + f)] / 2} (III) (wherein R ⁴ is a substitution not containing an aliphatic unsaturated bond) Or e represents an unsubstituted monovalent hydrocarbon group, e represents a number of 1.9 to 2.2, f represents a number of 0 to 0.1, and e + f represents 1.9 to 2.2. A))
Polydiorganosiloxane viscosity is more than 300,000cP at 25 ° C., component (A) 0.5 to 20 parts by weight per 100 parts by weight (E) Formula ^{(IV): R 5 -0- (} CH 2 CH 2 O) _n H (IV) (wherein, R ⁵ represents an alkyl group or an alkenyl group;
Represents an integer of from 2 to 15), wherein 3 to 40 parts by weight of an alkyl ether or alkenyl ether of polyoxyethylene represented by