JPH0480264A - Addition-vulcanizing silicone rubber composition and its cured product - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides an addition-vulcanized silicone rubber composition, particularly a molded article with a long pot life and no foaming after kneading a curing agent and a catalyst. The present invention also relates to an addition vulcanization type silicone rubber composition and a cured product thereof, which are useful for extrusion molded parts such as medical parts and tubes because of their excellent transparency and extrusion moldability.

(Prior art) Silicone rubber has excellent heat resistance, cold resistance, and weather resistance, provides transparent molded products, and is also excellent in biocompatibility, so it is widely used as medical parts. Silicone rubber used in various fields is generally of the addition vulcanization type, but when a crosslinking agent and catalyst are kneaded into the addition vulcanization type silicone rubber, vulcanization progresses even at room temperature. This usually includes benzotriazole,
Vulcanization retarders (control agents) such as acetylene alcohol derivatives, triphenyl phosphite, etc. are added as appropriate.

(Problems to be Solved by the Invention) However, this addition vulcanization type silicone rubber does not have enough vulcanizability to extrude the composition and vulcanize it by atmospheric pressure hot air vulcanization (l(AV)). When the above-mentioned control agent is applied to give a longer usage time, foaming is often observed in the extruded product, so in order to suppress this foaming, it is necessary to increase the amount of catalyst, decrease the amount of control agent, or add a compound. Increasing the plasticity of will shorten the pot life,
The disadvantages are that the extrusion properties are significantly impaired, the workability is poor, and the appearance of the molded product is poor.

(Means for Solving the Problems) The present invention relates to an addition-vulcanized silicone rubber composition and a cured product thereof, which solve the above-mentioned disadvantages. R1 is the same or different unsubstituted or substituted monovalent hydrocarbon group, a is a positive number of 1.98 to 2.01), and contains at least two alkenyl groups in one molecule, the degree of polymerization is 3,0
100 parts by weight of organopolysiloxane of 00 or higher, B)
Suruganovorisiloxane as the above A) component, which contains an average of more than 2 hydrogen atoms bonded to a silicon atom (SjH group) in one molecule, D) component described later, and E) component 0.5 to 4 f for a total of 1 alkenyl group
organohydropolysiloxane in an amount that accounts for the siH groups, C) 5 to 100 parts by weight of reinforcing silica filler with a specific surface area of 150 m2/g or more, D) - Formula R2bSj (O
R3) 4-1+ (where R2 is the same or different unsubstituted or substituted monovalent hydrocarbon group, R3 is an alkyl group or alkoxyalkyl group having 1 to 6 carbon atoms, b is an integer of 0 to 3) Alfukidisilane or its partial hydrolyzate 0.5 to 20 parts by weight, E) - Formula R4csic
Organochlorosilanes 10-5. OOOppm,
F) 10 to 5,000 ppm of a platinum-based catalyst selected from platinum or a platinum compound.

That is, the present inventors conducted various studies to develop an addition-vulcanized silicone rubber composition that does not have the disadvantages mentioned above, and as a result, the above-mentioned A), B), il:) and F) were obtained.
Addition of the alkoxysilane or its partial hydrolyzate as component D and the organochlorosilane as component E) to a conventionally known addition-vulcanized shisocone rubber composition consisting of the following components improves the transparency of this composition. However, it has been found that even when the above-mentioned control agent is added to this material, the convenience of no foaming is provided when it is extruded and HAV vulcanized, and therefore, it has excellent transparency. We have confirmed that it is possible to obtain an addition-vulcanized silicone rubber composition that has a long pot life after addition of a curing agent and a catalyst, provides foam-free molded products, and has excellent extrusion moldability, and has developed the present invention. Completed.

This will be explained in further detail below.

(Function) The present invention relates to an addition-vulcanized silicone rubber composition with improved physical properties and a cured product thereof.

A) constituting the addition-vulcanized silicone rubber composition of the present invention
The average compositional formula of organopolysiloxane as a component is R'@5iO4-i (1), and R
1 is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an octyl group, a cycloalkyl group such as a cyclohexyl group, an alkenyl group such as a vinyl group or an allyl group, an aryl group such as a phenyl group or a tolyl group, or A chloromethyl group, a 3,3,3-trifluoropropyl group, a 2-
Usually has 1 to 1 carbon atoms, selected from cyanoethyl groups, etc.
0, preferably the same or different unsubstituted or substituted monovalent hydrocarbon groups having 1 to 8 carbon atoms, where a is a positive number of 1.98 to 2.1; Since the product is an addition vulcanization type, it is required to contain at least two alkenyl groups in one molecule, and if the degree of polymerization is less than 3,000, extrusion processability is poor. In addition, the resulting molded product will have weak mechanical strength and poor moldability, so it is recommended to use a linear woody diorganopolysiloxane with a degree of polymerization of 3,000 or more. Although required, this may include some branched structures.

In addition, the organopitrodiene polysiloxane as component B, which constitutes this addition-vulcanized silicone rubber composition, acts as a crosslinking agent for the above-mentioned component A). A hydrogen atom (=SiH group) bonded to a silicon atom is added to the alkenyl group as an aliphatic unsaturated group in the presence of a platinum-based catalyst as component F), which will be described later. It is necessary to have an average number of =Si)l groups in one molecule of more than 2, preferably at least 3, and therefore it requires H5i
Osyz,C)I,)ISiO2(CH3)2H5i
Siloxane units with =Si)I bonds such as O+72 and SiO□, CH35i037□, C6H55i03y
2, (CH3)25lO1CH3C6H5SiO1((
:6)+5)2-5iO1(C)+3)3sio+7
Examples include copolymers of methylhydrodiene polysiloxane and dimethylhydrodiene polysiloxane, and copolymers of methylhydrodiene polysiloxane and methylphenylpolysiloxane. Copolymer, methylhydrodienepolysiloxane, copolymer with dimethylpolysiloxane and diphenylpolysiloxane, (C1(3) 2-H5
iO+z2, CH35iOsi2, (CH3) 2si
Examples include copolymers consisting of O and 5i02, usually having 400 or less silicon atoms in one molecule.

The amount of the organohydrodiene polysiloxane to be added is such that 0.0.0. It is required that the amount is sufficient to supply 5 to 4 pieces.

Next, since the silica filler as component C) constituting the addition reaction type silicone rubber composition of the present invention is used for reinforcing the intended silicone rubber molded product, it has a specific surface area of 150 m"7 g or more. Examples of the silica filler include fumed silica and precipitated silica, but the surface of these may be pretreated with silane, siloxane, silazane, etc. The amount of the silica filler added is the same as the organopolysiloxane 1 as component A) described above.
If it is less than 5 parts by weight based on 00 parts by weight, it is too small and the desired strength and processability cannot be obtained, and if it is more than 100 parts by weight, it is difficult to incorporate it into the composition and the composition becomes hard. Since the molding processability is lowered and the mechanical strength of the cured product is inferior, it is necessary to use it in a range of 5 to 100 parts by weight, but the preferred range is 10 to 80 parts by weight.

D constituting the addition-vulcanized silicone rubber composition of the present invention
) The alkoxysilane or its partial hydrolyzate has the general formula R2bSi (OR3) <-b (2
), R2 is the same or different monovalent hydrocarbon group as R1 described above, usually having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and R3 is an unsubstituted or different monovalent hydrocarbon group having 1 to 6 carbon atoms. An alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an alkoxyalkyl group such as a methoxymethyl group, a methoxydiethyl group, an ethoxyethyl group, an ethoxymethyl group, and b is an integer of 0 to 3. This includes Si (OCH3)4, Si (QC2)1s)
a, CI(3S i (OCH3) 3, CH35i
(OC2H5) s, CH:+Si (OC3H7)
3.C)1. ．． 5i (OC2H40CH3) 3, (
CH3) 2Si-(OCH3)2, (CH3) 2s
i (OC2H5) 2, (C)13) 35! QC
)+3, (CH3), 5iOc21(5, CH2-C
)lsi (OCH3) 3, CH2-CH5i-(O
C2Hs) 3, (CH3) (CH2-CH) Si
(OCH3) 2, (CH3) (CH2-CH)
5j (OC2H5) l (CH3) 2 (CH2-
CH) 5iOCH3, (CH3) 2-(C)12-
CH) 5iOC2Hs, CB) 1ssi (OCH3
) 3, (:6H5Si-(QC2)15)! , (CH
s) (CsHs) Sl (OCH3) 2, (C
Hs) (C6)1s)-5i (OC2H5) x,
(C)13) 2 (C8H5) 5iOC2H40C
Hs, CF3CH2CH2-5i (QC)+3) s
, CF3CN2CH2Si (OCJs) 3, CF,
C) 12CH,5i-(OC3H7)3,CF3C:N
2CH2(C)+3) Si (OCH+) x, C
F, C) I2-(:N2 (CH3) Si (1)C
2) 1s) 2 and its partial hydrolysis.

If the amount of this substance added is less than 0.5 parts by weight based on 100 parts by weight of the organopolysiloxane as component A), it is too small and the transparency of the composition will not improve, and the composition will not be extruded. It also has the effect of preventing foaming during IAV vulcanization, but if the amount exceeds 20 parts by weight, the viscosity of this composition will decrease, resulting in poor moldability such as roll processability and extrusion processability. This should be in the range of 0.5 to 20 parts by weight since the mechanical strength of the molded product will be reduced.

Furthermore, the organochlorosilane as component E, which constitutes the addition-vulcanized silicone rubber composition of the present invention, has the general formula R'cSiCJ! , -c... (3), in which R4 is the same or different type as R1, usually having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, unsubstituted or substituted. A hydrocarbon group, where C is an integer from 1 to 3, including CH35iCus, (CH3)
zsicρ2, (CH3) 3SiCJ2, C2)1
5-5jCj23, (C2H5) 2sicJ22, (
C2H5), 5icu, CH2-CH-5iCI
13, (CH2-CH) (CHs) 5iCu 2,
(Ch-C)I) (CH3) 2-5iCJ2, C
6) 15SiCj23, (C)13) (C6H5)
Si(:u 2. (CJs) 2-5iC12, (C
H3) 2 (C6Hs) 5iCJ2, CF3CH2
CH25iCIl 3, CF3CH2CH2((:N3
) 5LCIl 2, CF3CH2CH2(C)+3)
2sjcj2 etc. 6 The amount of this organochlorosilane added is the same as the above-mentioned A.
) If it is less than ID ppm based on 100 parts by weight of the organopolysiloxane as a component, it is too small, and the transparency improvement effect of this composition due to the synergistic effect with the alkoxysilane or its partial hydrolyzate as the above-mentioned O) component, this composition When the product is extruded or vulcanized by IAV, the foaming prevention effect cannot be obtained, and if the amount exceeds 5,000 ppm, a decrease in viscosity and coloration due to cranking of the organopolysiloxane as the component (A) are observed, resulting in poor moldability and transparency. This needs to be in the range of 10 to 5.0 OOppm, since the properties of the oxides become poor.

Although the mechanism by which the addition of component D) and component E) improves the transparency of the composition and provides an anti-foaming effect during vulcanization is not necessarily clear, the addition of component E) reduces the hydrolysis of component D). This is thought to be due to the fact that the silica's surface properties and reactivity to silica are promoted, the degree of treatment of the silica surface is increased, the silica surface is made hydrophobic, its compatibility with organopolysiloxane is improved, and adsorbed water is further removed.

In addition, F constituting the addition-vulcanized silicone rubber of the present invention
) The platinum-based catalyst as a component is the above-mentioned organopolysiloxane as the component A), alkoxysilane or a partial hydrolyzate thereof as the component D, an alkenyl group contained in the organochlorosilane as the component E), and component 8). This is to promote the addition reaction with the EESiH bond contained in the organohydrodiene polysiloxane, but this may be a known one, such as platinum black, chloroplatinic acid, chloroplatinic acid, etc. Examples include alcohol-modified products of chloroplatinic acid, complex salts of chloroplatinic acid and ethylene or propylene, complex salts of chloroplatinic acid and vinylsiloxane, etc., and the amount added is based on 100 parts by weight of the organopolysiloxane as component A). However, the amount of platinum is 1
0-5, OOOppm range, preferably 50-1,
It may be within the range of 000 ppm.

The addition reaction vulcanizable silicone rubber composition of the present invention can be obtained by uniformly mixing predetermined amounts of the above-mentioned components A) to F), and this mixing is carried out by rolling these components.
Kneading may be carried out using a mixer such as a kneader or Banbury mixer, but this is generally done by mixing A) component organopolysiloxane, C) component reinforcing silica filler, and D) component alkoxysilane. or the partial hydrolyzate thereof and orkacchlorosilane as component E) are uniformly mixed and kneaded in advance, and then
After heat treatment at t for 30 minutes to 6 hours,
After filtering through a screen of ~200 mesh, the organopitrodiene polysiloxane as component B) and the platinum catalyst as component F) may be kneaded therein. Note that it is optional to add conventionally known addition reaction control agents such as benzotriazole, acetylene alcohol conductor, triphenyl phosphite, etc. to this composition, and according to this, the pot life can be adjusted to any desired value. The length can be adjusted, and known heat resistance improvers, various carbon functional silanes, etc. may optionally be added thereto.

The addition-vulcanized silicone rubber composition of the present invention thus obtained has a curing agent, a catalyst, a long pot life after kneading,
It has the property of being excellent in molding processability, and this molding is done by extruding the stiff material through a die using an extruder used for molding silicone rubber, and then molding it at a temperature of 250 to 450°C. 10 to 60 in the heating cylinder
A molded article having a desired shape is obtained by vulcanization and curing by residence for a second. In addition, like general silicone rubber, this product has excellent properties such as heat resistance, cold resistance, weather resistance, electrical properties, and compression recovery properties. Since it is advantageous in that it has excellent transparency, it is especially suitable as a medical component, and furthermore, as a tube.

(Example) Next, examples of the present invention and comparative examples will be given. In the examples, parts are parts by weight, and viscosity is a value measured at 25°C.

Example 1.2, Comparative Example 1 Consisting of 99.92 mol% dimethylsiloxane units and 0.08 mol% methylvinylsiloxane units, the molecular chain terminals are blocked with dimethylvinylsiloxacyl groups, and the average degree of polymerization is about a. , ooo, 97 parts of methylvinyl polysiloxane, 90 mol % of dimethyl siloxane units and 10 mol % of methyl vinyl siloxane units, the molecular chain terminals are blocked with dimethyl vinyl siloxane groups, and the average degree of polymerization is about 5. Organopolysiloxane consisting of 3 parts of methylvinylpolysiloxane with a specific surface area of 200 m'
/g of fumed silica, 210 parts of dimethyldimethoxysilane ((:H8hSi(OCH+)), 3 parts of α,ω-dimethylpolysiloxane-diol having a viscosity of 15 cS, and the amounts of dimethyldichlorosilane ( CH3) and 5tcJ22 were added, mixed uniformly using a kneader mixer, and heat treated at 170°C for 2 hours to produce compounds (A) and (B). Same as above except that this dimethyldichlorosilane was not added. Compound (C) was prepared with the following composition.

Next, these compounds (8) to (C) were divided into sheets with a thickness of 5 mm on two rolls, and 3 portions were placed in an oven at 250°C to examine the foaming state of the unvulcanized dough. As shown in Table 1, compounds (A) and (B
), but no foaming was observed in compound (C).
Fine foaming was observed throughout.

Next, this compound (A), (B), (C) 10
0 parts of methylhydropolysiloxane 1.3
0.05 part of ethynylcyclohexanol as an addition reaction control agent and 1100 pp of platinum were added, kneaded with two rolls, and an unvulcanized dough with a thickness of about 2 mm was separated at 150°C and 30 kgf/cm2. Press molding was performed for 10 minutes at 200°C, followed by secondary vulcanization at 200°C for 4 hours to prepare test pieces and examine their physical properties.The results shown in Table 1 were obtained. When the foaming state of the unvulcanized dough cut into 5 mm pieces was cured by heating at 400° C. for 30 seconds in a vulcanization tower, the results shown in Table 1 were obtained.

Table (remarks) Transparency/light transmission turbidity meter used (test piece 6 mmt
, water measured 0) Examples 3 to 5 The organochlorosilane as component E) in Example 1 was replaced with trimethylchlorosilane (CH3)3sicfl.
Compounds (D), (E), (
F) was prepared and used in the same tests as in Example 1, and the results shown in Table 2 were obtained.

Contrary Example 6, Comparative Examples 2 to 3 The compound (A) prepared in Example 1 and the compound (C) prepared in Comparative Example 1 were added to the methylhydrodiene polysiloxane used in Example 1 and the addition reaction control agent. Ethynylcyclohexanol as a catalyst and platinum as a catalyst are added in the amounts shown in Table 3 to prepare an addition-vulcanized silicone rubber composition, which is heated in a vulcanization tower at 400°C for 30 seconds to form an HAV. When we examined the foaming state when cured by vulcanization and the pot life when this composition was left at room temperature, the results shown in Table 3 were obtained, indicating that the addition vulcanization type silicone rubber composition of the present invention It was confirmed that the product did not foam, had a long pot life, and was therefore highly workable.

弗 table (remarks) Pot life OK... NG... Chews formed by extrusion Her skin is good and no gel-like substances are visible. I can't stand it.

Chews formed by extrusion I noticed rough skin on my body, and Loop-like substances are also recognized.

(Effects of the Invention) The present invention relates to an addition-vulcanized silicone rubber composition with excellent transparency and extrusion processability, and a cured product thereof. ) organohydrodiene polysiloxane, C) reinforcing silica filler, 0) alkoxysilane or its partial hydrolyzate, E) organochlorosilane, and F) platinum-based catalyst. According to this, A) , B), C) and F) are added with alkoxysilane or its partial hydrolyzate as component D) and organochlorosilane as component E), so this composition is transparent. Its extrusion processability is improved, and there is no foaming during vulcanization even though an addition reaction control agent is added, so the pot life is longer.
The advantage is that an addition-vulcanized silicone rubber composition with excellent transparency and extrudability, which gives molded articles without foaming, can be obtained.

Patent applicant: Shin-Etsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. A) Average composition formula▲There are mathematical formulas, chemical formulas, tables, etc.▼
(Here, R^1 is the same or different unsubstituted or substituted monovalent hydrocarbon group, a is a positive number from 1.98 to 2.01), and at least two alkenyl groups in one molecule. B) 100 parts by weight of an organopolysiloxane with a degree of polymerization of 3,000 or more, containing hydrogen atoms bonded to silicon atoms in one molecule (≡Si
Organopolysiloxane as component A) containing more than 2 H groups) on average, component D) described below, and component E
) Organohydrodiene polysiloxane in an amount that provides 0.5 to 4 ≡SiH groups per total alkenyl group contained in the component, C) Reinforcement with a specific surface area of 150 m^2/g or more D) General formula R^2_bSi(OR^3)_4_-_b(
Here R^2 is the same or different unsubstituted or substituted 1
alkoxysilane represented by a valent hydrocarbon group, R^3 is an alkyl group or alkoxyalkyl group having 1 to 6 carbon atoms, and b is an integer of 0 to 3, or a partial hydrolyzate thereof 0.5 to
20 parts by weight, E) General formula R^4_cSiCl_4_-_c (where R
^4 is the same or different unsubstituted or substituted monovalent hydrocarbon group, C is an integer of 1 to 3) 10 to 5,000 ppm of organochlorosilane; F) a platinum-based catalyst selected from platinum or a platinum compound; 1
0 to 5,000 ppm, an addition vulcanization type silicone rubber composition. 2. A cured product obtained by curing the composition according to claim 1.