JP7156216B2 - Millable type silicone rubber composition, cured product thereof, and silicone rubber compound for millable type silicone rubber composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a millable type silicone rubber composition, a cured product thereof , and a silicone rubber compound for the millable type silicone rubber composition .

Silicone rubber has excellent weather resistance, electrical properties, low compression set, heat resistance, and cold resistance. in use. For example, rubber contacts used as rubber contacts for remote controllers, typewriters, word processors, computer terminals, musical instruments, etc.; construction gaskets; rolls for copiers, developing rolls, transfer rolls, charging rolls, paper feed rolls, etc. anti-vibration rubber for audio equipment; and packing for compact discs used in computers. Currently, the demand for silicone rubber is increasing more and more, and the development of silicone rubber having excellent properties is desired. These silicone rubbers generally contain an organopolysiloxane raw rubber with a high degree of polymerization (that is, a non-liquid raw rubber-like organopolysiloxane that is not self-flowing at room temperature) and a reinforcing filler, and a curing agent ( A millable type silicone rubber compound (i.e., a compound that can be kneaded with a kneader such as a roll mill) before blending with a vulcanizing agent), and a millable type silicone rubber composition in which a curing agent is blended into this compound (i.e., a roll mill, etc. It is used in the form of a composition that can be kneaded with a kneader. The millable type silicone rubber compound and silicone rubber composition are prepared by mixing reinforcing fillers and various dispersing agents into the raw material polymer (rubber-like organopolysiloxane) using a mixing device such as a kneader or a two-roll mill (roll mill). It is prepared by

In order to produce a millable type silicone rubber compound and a silicone rubber composition, as described above, it is necessary to knead a reinforcing filler such as fumed silica into the organopolysiloxane. A reinforcing filler surface treatment agent called wetter is used. Ordinarily, when dispersing a reinforcing filler such as silica in an organopolysiloxane, an organosilane or siloxane having a silanol group is used. By using a large amount of this surface treatment agent, crepe hardening (plasticity reversion) can be suppressed. However, there was a drawback that the workability deteriorated due to the occurrence of a feeling. On the other hand, when the addition amount of the surface treatment agent is not sufficient, there is a problem that the crepe hardening (plasticity reversion) increases although the plasticity increases.

JP-A-6-256658 (Patent Document 1) describes adding a resin, and JP-A-5-065415 (Patent Document 2) describes adding a polycyclic aromatic compound having two or more phenyl groups. Although it is described that the plasticity can be increased by reducing the plasticity, there is no description of plasticity reversion, and the cost is high. Further, Japanese Patent Application Laid-Open No. 7-133356 (Patent Document 3) describes that replasticization can be suppressed by heating a silicone rubber compound at 200 to 250° C. for 4 to 12 hours, but this is not economical. . Japanese Patent Application Laid-Open No. 2015-214635 (Patent Document 4) describes that the plasticity is increased by adding a condensation reaction catalyst such as organosilane and/or siloxane and an organic titanium compound blocked with silanol groups at both ends. However, it is necessary to add it at the time of blending silica and heat treatment after adding the condensation catalyst.

JP-A-6-256658 JP-A-5-065415 JP-A-7-133356 JP 2015-214635 A

The present invention has been made in view of the above circumstances, and provides a millable type silicone rubber composition and its curing that increase plasticity in an economical manner without the need for the addition of expensive compounds or long-term heat treatment at high temperatures. and a silicone rubber compound for a millable type silicone rubber composition .

As a result of intensive studies to achieve the above object, the present inventors have found that an organopolysiloxane raw rubber (base polymer) having a degree of polymerization of 100 or more (especially 1,000 or more) and reinforcing silica are uniformly kneaded. When preparing a silicone rubber compound by (mixing) and/or after preparation, an organopolysiloxane having an aliphatic unsaturated group at one end of the molecular chain and a silanol group at the other end is used, and an aminoxy group is added. The inventors have found that a millable type silicone rubber compound with increased plasticity can be obtained by adding a nitrogen atom-containing organosilicon compound having an average of 2 or more nitrogen atoms per molecule, and have completed the present invention.

（式中、Ｒ²は脂肪族不飽和基であり、Ｒ³は同一又は異種の非置換若しくは置換の１価炭化水素基であり、ｎは１００以上の正数である。）
で表されるオルガノポリシロキサン １～５０質量部、
（Ｃ）ＢＥＴ吸着法による比表面積が５０ｍ²／ｇ以上の補強性シリカ
５～１００質量部、
（Ｄ）ケイ素原子に結合した下記式（３）及び（４）で表される置換アミノキシ基から選ばれる１種又は２種以上の基を１分子あたり平均２個以上有する窒素原子含有有機ケイ素化合物 ０．００１～１５質量部、

（式中、Ｒ⁴及びＲ⁵は互いに同一又は異種の１価炭化水素基である。Ｒ⁶は２価の有機基である。）
（Ｅ）硬化剤 有効量
を含有することを特徴とするミラブル型シリコーンゴム組成物。
２．
（Ｄ）成分が、下記式（５）～（８）で表される有機ケイ素化合物から選ばれる１種又は２種以上である上記１記載のミラブル型シリコーンゴム組成物。

（式中、Ｒ⁷は同一又は異種の置換若しくは非置換１価炭化水素基であり、ＯＹは上記式（３）又は（４）で示される基、ｂは０、１又は２、ｃは０又は１０以下の正数である。ｌは１～２０の正数、ｍは２～２０の正数であり、且つｌ＋ｍは３以上の正数である。Ｒ’はＲ⁷又はＯＹであり、ｐ、ｑはそれぞれ独立に０又は１００以下の正数であり、ｑが０以上１未満の場合は２つのＲ’はＯＹであり、ｑが１以上２未満の場合はＲ’の少なくとも１つはＯＹである。Ｑは炭素数１～２０の２価炭化水素基である。）
３．
（Ｅ）成分の硬化剤が、オルガノハイドロジェンポリシロキサンとヒドロシリル化触媒との組み合せからなる付加反応硬化型である上記１又は２に記載のミラブル型シリコーンゴム組成物。
４．
（Ｅ）成分の硬化剤が有機過酸化物である上記１又は２に記載のミラブル型シリコーンゴム組成物。
５．
（Ｅ）成分の硬化剤が、オルガノハイドロジェンポリシロキサンとヒドロシリル化触媒との組み合せと、有機過酸化物とを併用したものである上記１又は２に記載のミラブル型シリコーンゴム組成物。
６．
上記１～５のいずれかに記載のミラブル型シリコーンゴム組成物を硬化してなるシリコーンゴム硬化物。
７．
（Ａ）下記平均組成式（１）
Ｒ ¹ _a ＳｉＯ _(4-a)/2 （１）
（式中、Ｒ ¹ は同一又は異種の非置換若しくは置換の１価炭化水素基であり、ａは１．９５～２．０５の正数である。）
で表される重合度が１００以上のオルガノポリシロキサン １００質量部、
（Ｂ）下記式（２）

（式中、Ｒ ² は脂肪族不飽和基であり、Ｒ ³ は同一又は異種の非置換若しくは置換の１価炭化水素基であり、ｎは１００以上の正数である。）
で表されるオルガノポリシロキサン １～５０質量部、
（Ｃ）ＢＥＴ吸着法による比表面積が５０ｍ ² ／ｇ以上の補強性シリカ
５～１００質量部、
（Ｄ）ケイ素原子に結合した下記式（３）及び（４）で表される置換アミノキシ基から選ばれる１種又は２種以上の基を１分子あたり平均２個以上有する窒素原子含有有機ケイ素化合物 ０．００１～１５質量部、

（式中、Ｒ ⁴ 及びＲ ⁵ は互いに同一又は異種の１価炭化水素基である。Ｒ ⁶ は２価の有機基である。）
を含有するミラブル型シリコーンゴム組成物用シリコーンゴムコンパウンド。 Accordingly, the present invention provides the following millable type silicone rubber composition, a silicone rubber cured product obtained by curing the composition, and a silicone rubber compound for the millable type silicone rubber composition .
1.
(A) the following average composition formula (1)
R1aSiO(4- _{a )/2} ( ¹ )
(In the formula, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and a is a positive number of 1.95 to 2.05.)
100 parts by mass of organopolysiloxane having a degree of polymerization of 100 or more represented by
(B) Formula (2) below

(In the formula, R ² is an aliphatic unsaturated group, R ³ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and n is a positive number of 100 or more.)
1 to 50 parts by mass of organopolysiloxane represented by
(C) Reinforcing silica having a specific surface area of 50 m ² /g or more as determined by the BET adsorption method
5 to 100 parts by mass,
(D) A nitrogen atom-containing organosilicon compound having an average of two or more groups per molecule, selected from substituted aminoxy groups represented by the following formulas (3) and (4), bonded to silicon atoms: 0.001 to 15 parts by mass,

(In the formula, R ⁴ and R ⁵ are the same or different monovalent hydrocarbon groups, and R ⁶ is a divalent organic group.)
(E) Curing agent A millable type silicone rubber composition characterized by containing an effective amount.
2.
2. The millable type silicone rubber composition according to 1 above, wherein component (D) is one or more selected from organosilicon compounds represented by the following formulas (5) to (8).

(Wherein, R ⁷ is the same or different substituted or unsubstituted monovalent hydrocarbon group, OY is a group represented by the above formula (3) or (4), b is 0, 1 or 2, c is 0 or a positive number of 10 or less, l is a positive number of 1 to 20, m is a positive number of 2 to 20, and l+m is a positive number of 3 or more, R' is R ⁷ or OY, p and q are each independently a positive number of 0 or 100 or less, and when q is 0 or more and less than 1, two R' are OY, and when q is 1 or more and less than 2, at least one of R' is OY. Q is a divalent hydrocarbon group having 1 to 20 carbon atoms.)
3.
3. The millable type silicone rubber composition according to 1 or 2 above, wherein the curing agent of component (E) is an addition reaction curing type comprising a combination of an organohydrogenpolysiloxane and a hydrosilylation catalyst.
4.
3. The millable type silicone rubber composition according to 1 or 2 above, wherein the curing agent of component (E) is an organic peroxide.
5.
3. The millable type silicone rubber composition as described in 1 or 2 above, wherein the curing agent (E) is a combination of an organohydrogenpolysiloxane and a hydrosilylation catalyst and an organic peroxide.
6.
6. A cured silicone rubber obtained by curing the millable type silicone rubber composition according to any one of 1 to 5 above.
7.
(A) the following average composition formula (1)
R1aSiO ( 4 - _{a )/2} (1 ⁾
(In the formula, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and a is a positive number of 1.95 to 2.05.)
100 parts by mass of organopolysiloxane having a degree of polymerization of 100 or more represented by
(B) Formula (2) below

(In the formula, R ² is an aliphatic unsaturated group, R ³ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and n is a positive number of 100 or more.)
1 to 50 parts by mass of organopolysiloxane represented by
(C) Reinforcing silica having a specific surface area of 50 m ² /g or more as determined by the BET adsorption method
5 to 100 parts by mass,
(D) A nitrogen atom-containing organosilicon compound having an average of two or more groups per molecule, selected from substituted aminoxy groups represented by the following formulas (3) and (4), bonded to silicon atoms: 0.001 to 15 parts by mass,

(In the formula, R ⁴ and R ⁵ are the same or different monovalent hydrocarbon groups, and R ⁶ is a divalent organic group.)
A silicone rubber compound for a millable type silicone rubber composition containing

In the present invention, the mixture obtained by blending the above components (A) to (D) and before blending the curing agent is referred to as a (millable type) silicone rubber compound. type) is called a silicone rubber composition.

According to the millable type silicone rubber composition of the present invention, one end of the molecular chain is an aliphatic unsaturated group and the other end is a silanol group, without the addition of expensive compounds or long-term heat treatment at high temperatures. By adding an organopolysiloxane and a nitrogen atom-containing organosilicon compound having a predetermined substituted aminoxy group, the plasticity can be economically increased, and curing can give a silicone rubber cured product. .

The present invention will be described in more detail below.

-(A) component-
In the present invention, component (A) is the main ingredient (base polymer) in the millable type silicone rubber composition, and is an organopolysiloxane having a degree of polymerization of 100 or more represented by the following average compositional formula (1).
R1aSiO(4- _{a )/2} ( ¹ )
(In the formula, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and a is a positive number of 1.95 to 2.05.)

In the average composition formula (1), R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group. The monovalent hydrocarbon group usually has 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, and specifically includes methyl, ethyl, propyl, butyl, hexyl, octyl and the like Cycloalkyl groups such as alkyl groups, cyclopentyl groups, cyclohexyl groups; alkenyl groups such as vinyl groups, allyl groups, propenyl groups, butenyl groups and hexenyl groups; cycloalkenyl groups such as cyclohexenyl groups; aryl groups such as phenyl groups and tolyl groups; benzyl group, aralkyl group such as 2-phenylethyl group, or part or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, chlorine, or cyano group, such as chloromethyl group, trifluoro Examples include a propyl group and a cyanoethyl group. Among the above, a methyl group, a vinyl group, a phenyl group and a trifluoropropyl group are preferred, and a methyl group and a vinyl group are particularly preferred.

In particular, the organopolysiloxane as the component (A) has 2 or more, usually 2 to 50, especially about 2 to 20 aliphatic unsaturated groups such as alkenyl groups and cycloalkenyl groups in one molecule. are preferred, and those having a vinyl group are particularly preferred. In this case, it is preferable that 0.01 to 20 mol %, particularly 0.02 to 10 mol % of all R ¹ are aliphatic unsaturated groups. The aliphatic unsaturated group may be bonded to a silicon atom at the terminal of the molecular chain, bonded to a silicon atom in the middle of the molecular chain (non-terminal of the molecular chain), or both. is preferably bonded to at least the silicon atom at the terminal of the molecular chain.
In addition, 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more of all R ¹ , more preferably all R ¹ excluding aliphatic unsaturated groups are alkyl groups, particularly methyl groups. is desirable.

a is a positive number of 1.95 to 2.05, preferably 1.98 to 2.02, more preferably 1.99 to 2.01.

The molecular structure of the component (A) organopolysiloxane is preferably linear or partially branched linear. Specifically, the repeating structure of the diorganosiloxane units (R ^{12 SiO 2/2 , R 1} _is ^the same as above and hereinafter the same) constituting the main chain of the organopolysiloxane is _changed from repeating only dimethylsiloxane units to or a diphenylsiloxane having a phenyl group, a vinyl group, a 3,3,3-trifluoropropyl group, etc. as a substituent as part of the dimethylpolysiloxane structure consisting of repeating dimethylsiloxane units constituting the main chain Units into which diorganosiloxane units such as methylphenylsiloxane units, methylvinylsiloxane units, methyl-3,3,3-trifluoropropylsiloxane units are introduced are suitable.

Both ends of the molecular chain are, for example, triorganosiloxy groups (R ¹³ SiO _1/2 ) such as trimethylsiloxy group, dimethylphenylsiloxy group, vinyldimethylsiloxy group, _{divinylmethylsiloxy} group and trivinylsiloxy group. It is preferably closed.

Such organopolysiloxanes can be prepared, for example, by (co)hydrolytic condensation of one or more organohalogenosilanes, or by using cyclic polysiloxanes (siloxane trimers, tetramers, etc.) in an alkaline or It can be obtained by ring-opening polymerization using an acidic catalyst.

The degree of polymerization of the organopolysiloxane is 100 or more (usually 100 to 100,000), preferably 1,000 to 100,000, more preferably 2,000 to 50,000, particularly preferably 3,000 to 20,000 and is so-called raw rubber-like (non-liquid) without self-fluidity at room temperature (25°C). If the degree of polymerization is too small, problems such as roll sticking will occur in compounding, and roll workability will deteriorate. The degree of polymerization can be measured as a weight-average degree of polymerization in terms of polystyrene by gel permeation chromatography (GPC) analysis (hereinafter the same).

Component (A) may be used singly or as a mixture of two or more different molecular weights (degrees of polymerization) and molecular structures.

（式中、Ｒ²は脂肪族不飽和基であり、Ｒ³は同一又は異種の非置換若しくは置換の１価炭化水素基であり、ｎは１００以上の正数である。） -(B) component-
Component (B) is an organopolysiloxane having a degree of polymerization of 100 or more represented by the following formula (2). It reacts with the component (D) to form raw rubber with a large molecular weight, which can increase plasticity.

(In the formula, R ² is an aliphatic unsaturated group, R ³ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and n is a positive number of 100 or more.)

In the average composition formula (2), R ² is an aliphatic unsaturated group having 1 to 8 carbon atoms, and specifically, an alkenyl group such as vinyl, allyl, propenyl, butenyl, hexenyl, cyclo It has a cycloalkenyl group such as a hexenyl group, etc., and is particularly preferably a vinyl group.

In the above average composition formula (2), R ³ is the same or different unsubstituted or substituted monovalent hydrocarbon group, usually having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, specifically includes alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group and octyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; alkenyl groups such as vinyl group, allyl group and propenyl group; aryl groups such as alkenyl groups, phenyl groups and tolyl groups; aralkyl groups such as benzyl groups and 2-phenylethyl groups; substituted with, for example, a chloromethyl group, a trifluoropropyl group, a cyanoethyl group and the like, preferably a methyl group, a vinyl group, a phenyl group and a trifluoropropyl group, particularly preferably a methyl group and a vinyl group.

n represents the degree of polymerization of (B) organopolysiloxane and is a positive number of 100 or more, preferably 2,000 to 50,000, more preferably 3,000 to 20,000. If n is less than 100, the plasticity may not increase.

The molecular structure of the component (B) organopolysiloxane is linear with one end of the molecular chain being an aliphatic unsaturated group and the other end being a silanol group. Specifically, one of both ends of the molecular chain is blocked with a diorganohydroxysiloxy group (R ³² (HO)SiO _1/2 ) such as a dimethylhydroxysiloxy group, and the other end is a _{vinyldimethylsiloxy} group, divinylmethyl It is blocked with a siloxy group or a trivinylsiloxy group. In addition, the repeating structure of the diorganosiloxane units (R ³ ₂ SiO _2/2 , R ³ is the same as above) constituting the main chain of the organopolysiloxane consists only of repeating dimethylsiloxane units, or Diphenylsiloxane units and methylphenylsiloxane units having phenyl groups, vinyl groups, 3,3,3-trifluoropropyl groups, etc. as substituents as part of the dimethylpolysiloxane structure consisting of repeating dimethylsiloxane units forming a chain , a methylvinylsiloxane unit, a methyl-3,3,3-trifluoropropylsiloxane unit, or the like into which a diorganosiloxane unit is introduced.

Component (B) is added in an amount of 1 to 50 parts by mass, preferably 5 to 30 parts by mass, per 100 parts by mass of organopolysiloxane as component (A). If the amount of component (B) is too small, the plasticity may not increase, and if it is too large, the physical properties of the cured silicone rubber may deteriorate.

-(C) component-
Component ⁽ C), reinforcing silica, is a filler added to obtain cured silicone rubber with excellent mechanical strength. or more, preferably 100 to 450 m ² /g, more preferably 100 to 300 m ² /g. If the specific surface area is less than 50 m ² /g, the mechanical strength of the cured product will be low.

Examples of such reinforcing silica include fumed silica, precipitated silica (wet silica), and the like, and the surfaces of these may be coated with organosilane compounds such as methylchlorosilane and hexamethyldisilazane. Hydrophobic treatment with a silazane compound or the like is also preferably used. Among these, fumed silica is preferable because of its excellent dynamic fatigue properties.
Component (C) may be used alone or in combination of two or more.

The amount of reinforcing silica as component (C) is 5 to 100 parts by mass, preferably 10 to 50 parts by mass, per 100 parts by mass of organopolysiloxane as component (A). If the amount of the component (C) is too small, no reinforcing effect can be obtained, and if it is too large, the processability will deteriorate, the mechanical strength will decrease, and the dynamic fatigue durability will also deteriorate. put away.

In the present invention, (C) a dispersant (wetter) for reinforcing silica can be blended as an optional component, if necessary. As this wetter, for example, a silane compound containing a silanol group (that is, a silicon atom-bonded hydroxyl group) such as diphenylsilanediol, which does not contain an aliphatic unsaturated group and which is distinguished from the component (B), or a silane compound at both ends of the molecular chain From silanol group-containing organosiloxane oligomers such as silanol group-blocked linear dimethylsiloxane oligomers (for example, low polymerization polymers having a degree of polymerization or a number of silicon atoms in the molecule of 2 to 30, particularly about 3 to 20) One or two or more selected are used. In the millable type silicone rubber composition of the present invention, when blending the wetter, the wetter is added after the component (B) and the component (D) described later are mixed, or (C) the reinforcing silica and the wetter are premixed. It is preferable to react with
The wetter content is preferably 0 to 25 parts by mass, more preferably 3 to 20 parts by mass, per 100 parts by mass of the base polymer (component (A)). .

（式中、Ｒ⁴及びＲ⁵は互いに同一又は異種の１価炭化水素基である。Ｒ⁶は２価の有機基である。） -(D) component-
Component (D) is a nitrogen atom-containing organosilicon compound, which reacts with component (B) to liberate a hydroxyamino compound. It has an average of two or more groups selected from substituted aminoxy groups represented by the following general formulas (3) and (4), which are bonded to silicon atoms per molecule.

(In the formula, R ⁴ and R ⁵ are the same or different monovalent hydrocarbon groups, and R ⁶ is a divalent organic group.)

In the above general formula (3), the monovalent hydrocarbon groups represented by R ⁴ and R ⁵ include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group and hexyl group. , octyl group, 2-ethylhexyl group, nonyl group, alkyl group such as decyl group, cycloalkyl group such as cyclohexyl group, aryl group such as phenyl group, aralkyl group such as benzyl group, etc. having 1 to 10 carbon atoms , in particular those having 1 to 6 carbon atoms and having no aliphatic unsaturated bonds.

In general formula (4) above, the divalent organic group represented by R ⁶ may contain a nitrogen atom or an oxygen atom and may have an aromatic ring in the structure. Examples include divalent hydrocarbon groups having 3 to 10 carbon atoms, particularly 4 to 8 carbon atoms, such as divalent residue of a membered ring, and specific examples include the following divalent organic groups. exemplified.

（式中、Ｒ⁷は同一又は異種の置換若しくは非置換１価炭化水素基であり、ＯＹは上記式（３）又は（４）で示される基、ｂは０、１又は２、ｃは０又は１０以下の正数である。ｌは１～２０の正数、好ましくは１～１０の正数であり、ｍは２～２０の正数、好ましくは２～１０の正数であり、且つｌ＋ｍは３以上の正数である。Ｒ’はＲ⁷又はＯＹであり、ｐ、ｑはそれぞれ独立に０又は１００以下の正数、好ましくは２～５０の正数であり、ｑが０以上１未満の場合は２つのＲ’はＯＹであり、ｑが１以上２未満の場合はＲ’の少なくとも１つはＯＹである。Ｑは炭素数１～２０の２価単価水素基である。） Examples of the nitrogen atom-containing organosilicon compound include those represented by the following formulas (5) to (8) (for example, silane compounds, siloxane compounds, silalkylene compounds such as silethylene compounds, silarylene compounds such as silphenylene compounds, etc.), and one or two or more selected from these are used.

(Wherein, R ⁷ is the same or different substituted or unsubstituted monovalent hydrocarbon group, OY is a group represented by the above formula (3) or (4), b is 0, 1 or 2, c is 0 or a positive number of 10 or less, l is a positive number of 1 to 20, preferably a positive number of 1 to 10, m is a positive number of 2 to 20, preferably a positive number of 2 to 10, and l+m is a positive number of 3 or more, R' is R ⁷ or OY, p and q are each independently a positive number of 0 or 100 or less, preferably a positive number of 2 to 50, and q is 0 or more Two R' are OY when q is less than 1, and at least one of R' is OY when q is 1 or more and less than 2. Q is a monovalent divalent hydrogen group having 1 to 20 carbon atoms. )

Examples of R ⁷ include alkyl groups, alkenyl groups, cycloalkyl groups, aryl groups, aralkyl groups, halogenated hydrocarbon groups and cyanohydrocarbon groups having 1 to 10 carbon atoms, particularly 1 to 8 carbon atoms. be done. Further, Q is a divalent hydrocarbon having 1 to 20 carbon atoms, particularly 1 to 10 carbon atoms, such as an alkylene group such as a methylene group, an ethylene group, a propylene group, a tetramethylene group, an arylene group such as a phenylene group, etc. groups.

Specific examples of the component (D) include those shown below.

The nitrogen atom-containing organosilicon compound (D) used in the composition of the present invention is a cross-linking agent that causes a cross-linking reaction with the organopolysiloxane (B). ) on average 2 or more, preferably 2.05 to 10, more preferably 2.1 to 5, more preferably 2.2 groups selected from substituted aminoxy groups bonded to silicon atoms represented by It is necessary to have about 4 pieces. When the number of aminoxy groups is less than this (that is, when a nitrogen atom-containing organosilicon compound containing an average of less than 2 substituted aminoxy groups in the molecule is used), the cross-linking reaction (polymerization) is insufficient. becomes. The average value in this case means the number average value of the substituted aminoxy groups contained in one molecule of component (D).

Component (D) is preferably contained in an amount of 0.01 to 10 parts by mass, particularly preferably 0.01 to 5 parts by mass, per 100 parts by mass of organopolysiloxane of component (B).

-(E) component-
The curing agent is not particularly limited as long as it can cure component (A), and includes the following (E-1) addition reaction curing agent and (E-2) organic peroxide curing agent.

(E-1) Addition Reaction Curing Agent As the addition reaction curing agent (E-1), an organohydrogenpolysiloxane and a hydrosilylation catalyst are used in combination.

The organohydrogenpolysiloxane has 2 or more, preferably 3 or more, more preferably 3 to 200, and still more preferably about 4 to 100 silicon-bonded hydrogen atoms per molecule (that is, SiH group), it may have a linear, cyclic, branched, or three-dimensional network structure, and known organohydrogenpolysiloxanes are used as cross-linking agents for addition reaction-curable silicone rubber compositions. For example, an organohydrogenpolysiloxane represented by the following average compositional formula (9) can be used.
^R8rHsSiO ( ₄ - _{rs )/2} (9)

In the average composition formula (9), R ⁸ represents an unsubstituted or substituted monovalent hydrocarbon group, which may be the same or different, and preferably excludes aliphatic unsaturated bonds. . Generally, those having 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, are specifically exemplified by alkyl groups such as methyl group, ethyl group and propyl group, cycloalkyl groups such as cyclohexyl group, phenyl group and tolyl group. Aralkyl groups such as aryl groups, benzyl groups, 2-phenylethyl groups and 2-phenylpropyl groups, and groups in which some or all of the hydrogen atoms in these groups are substituted with halogen atoms, etc., e.g., 3, 3, 3 -trifluoropropyl group and the like.

r and s are 0<r<3, preferably 0.5≦r≦2.2, more preferably 1.0≦r≦2.0, 0<s≦3, preferably 0.002≦s ≤1.1, more preferably 0.005≤s≤1, 0<r+s≤3, preferably 1≤r+s≤3, more preferably 1.002≤r+s≤2.7.

Organohydrogenpolysiloxane has 2 or more, preferably 3 or more SiH groups in one molecule. good too. The organohydrogenpolysiloxane preferably has a viscosity at 25° C. of 0.5 to 10,000 mPa·s, particularly 1 to 300 mPa·s. The viscosity is a value measured by a rotational viscometer at 25°C (same below).

Specific examples of such organohydrogenpolysiloxanes include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, tris(hydrogendimethylsiloxy ) methylsilane, tris(hydrogendimethylsiloxy)phenylsilane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane/dimethylsiloxane cyclic copolymer, both ends trimethylsiloxy group-blocked methylhydrogenpolysiloxane, both ends trimethylsiloxy group-blocked Dimethylsiloxane/methylhydrogensiloxane copolymer, both ends dimethylhydrogensiloxy group-blocked dimethylpolysiloxane, both ends dimethylhydrogensiloxy group-blocked dimethylsiloxane/methylhydrogensiloxane copolymer, both ends trimethylsiloxy group-blocked methylhydro gensiloxane/diphenylsiloxane copolymer, methylhydrogensiloxane/diphenylsiloxane/dimethylsiloxane copolymer blocked with trimethylsiloxy groups at both ends, methylhydrogensiloxane/methylphenylsiloxane/dimethylsiloxane copolymer blocked with trimethylsiloxy groups at both ends, dimethylhydrogensiloxy group-blocked methylhydrogensiloxane/dimethylsiloxane/diphenylsiloxane copolymer at both ends, dimethylhydrogensiloxy group-blocked methylhydrogensiloxane/dimethylsiloxane/methylphenylsiloxane copolymer at both ends, (CH ₃ ) ₂ Copolymers consisting of HSiO _1/2 units, (CH ₃ ) ₃ SiO _1/2 units and SiO _4/2 units, copolymers consisting of (CH ₃ ) ₂ HSiO _1/2 units and SiO _4/2 units coalescence, copolymers consisting of (CH ₃ ) ₂ HSiO _1/2 units, SiO _4/2 units and (C ₆ H ₅ ) ₃ SiO _1/2 units; Alternatively, all of them may be substituted with other alkyl groups, phenyl groups, or the like.

The amount of the organohydrogenpolysiloxane compounded is preferably 0.1 to 40 parts by weight per 100 parts by weight of component (A). In addition, the proportion of silicon-bonded hydrogen atoms (≡SiH groups) to one aliphatic unsaturated bond (alkenyl group, diene group, etc.) in component (A) is preferably in the range of 0.5 to 10. A range of 0.7 to 5 is preferable. If the number is less than 0.5, the cross-linking may be insufficient and sufficient mechanical strength may not be obtained. Compression set may increase.

The hydrosilylation catalyst is a catalyst for the hydrosilylation addition reaction between the alkenyl groups of the component (A) and the silicon-bonded hydrogen atoms (SiH groups) of the organohydrogenpolysiloxane. Examples of hydrosilylation catalysts include platinum group metal-based catalysts, including simple platinum group metals and compounds thereof, and conventionally known catalysts for addition reaction-curable silicone rubber compositions can be used. For example, particulate platinum metal adsorbed on a carrier such as silica, alumina or silica gel, platinum catalyst such as platinic chloride, chloroplatinic acid, alcoholic solution of chloroplatinic acid hexahydrate, palladium catalyst, rhodium catalyst, etc. platinum or platinum compounds (platinum catalysts) are preferred.

The amount of the catalyst to be added should only promote the addition reaction, and is usually used in the range of 1 ppm by mass to 1% by mass in terms of the amount of platinum group metal relative to the organopolysiloxane of component (A). A range of -500 mass ppm is preferred. If the amount added is less than 1 mass ppm, the addition reaction may not be sufficiently accelerated, resulting in insufficient curing. It is small and may be uneconomical.

In addition to the above catalysts, addition reaction inhibitors may be used for the purpose of adjusting the curing speed in an amount within a range that does not impair the object of the present invention. Specific examples thereof include acetylene alcohol-based control agents such as ethynylcyclohexanol and tetracyclomethylvinylpolysiloxane. The addition reaction controller may be used singly or in combination of two or more.

(E-2) Organic peroxide curing agent (E-2) Examples of the organic peroxide curing agent include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, o-methyl benzoyl peroxide, 2,4-dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, di-t-butyl peroxide, t-butyl perbenzoate, 1,6 -hexanediol-bis-t-butyl peroxycarbonate and the like.

The amount of the organic peroxide to be added is preferably 0.1 to 10 parts by weight, particularly 0.2 to 5 parts by weight, per 100 parts by weight of component (A). If the amount is too small, curing may be insufficient, and if it is too large, the cured product of the silicone rubber may turn yellow due to decomposition residues of the organic peroxide. In addition, addition reaction curing and organic peroxide curing were used in combination with component (A) by combining components (E-1) and (E-2) within the ranges of the above amounts. It can also be a co-vulcanized silicone rubber composition.

[Other ingredients]
In addition to the above components, the silicone rubber composition of the present invention may optionally contain a filler such as crushed quartz, crystalline silica, diatomaceous earth, calcium carbonate, a coloring agent, and a tear strength. Various alkoxysilanes, especially phenyl group-containing alkoxysilanes and their hydrolysates, diphenylsilane diol, carbon It is optional to add known fillers and additives in thermosetting silicone rubber compositions such as functional silanes and silanol group-containing low-molecular-weight siloxanes distinct from component (B). Among these, when adding a component that reacts with component (D) such as alkoxysilane, its hydrolyzate, and silanol group-containing low-molecular-weight siloxane, the component should be added prior to component (D). The component (D) may be added after reacting with components other than the component (D), or the component may be added after the components (B) and (D) are mixed. Alternatively, the amount of component (D) added may be increased.

The order of blending components (A) to (E) is not particularly limited, but (i) a method of blending (E) component in a compound obtained by mixing components (A) to (D), or (ii) (A ), (B), and (C) are mixed together, the (D) component is added to the compound, and then the (E) component is blended. The method (ii) is preferable because the plasticity is more likely to increase.

According to the millable type silicone rubber composition of the present invention, in a silicone rubber base compound containing organopolysiloxane raw rubber (base polymer) having a degree of polymerization of 100 or more (especially 1,000 or more) and reinforcing silica, (B) An organopolysiloxane having an aliphatic unsaturated group at one molecular chain end and a silanol group at the other end and (D) a nitrogen atom-containing organosilicon compound having an average of two or more aminoxy groups per molecule are combined and added. By doing so, the plasticity can be improved over the silicone rubber compound to which these are not added (for example, the plasticity is preferably increased by +5% or more, more preferably by +10% or more over the silicone rubber compound to which these are not added). It becomes possible.

As the method for molding and curing this silicone rubber composition, conventional methods can be adopted, but as the molding method, the most suitable means for the purpose can be selected from injection molding, transfer molding, injection molding, compression molding, and the like. It is possible. As the curing conditions, heat treatment (primary vulcanization) conditions at 40 to 230° C. for about 3 seconds to 160 minutes can be employed. Further, secondary vulcanization (post-curing) may optionally be performed at 40 to 230° C. for about 10 minutes to 24 hours, if necessary.

[Silicone rubber cured product]
The cured silicone rubber according to the present invention is obtained by curing the aforementioned millable type silicone rubber composition of the present invention. At this time, the hardness (type A durometer hardness) measured by a durometer A hardness tester of the cured silicone rubber of the present invention by the method described in JIS K 6249:2003 is, for example, 50 or less, preferably 30 or more and 50 or less. is.

EXAMPLES Hereinafter, the present invention will be specifically described by showing examples and comparative examples, but the present invention is not limited to the following examples. As the plasticity, Williams plasticity was measured according to JIS K 6249:2003. The hardness is the hardness measured by a durometer A hardness tester (type A durometer hardness) measured by the method described in JIS K 6249:2003.

[Example 1]
80 parts by mass of linear dimethylpolysiloxane crude rubber having an average degree of polymerization of about 8,000, consisting of 99.975 mol% of dimethylsiloxane units and 0.025 mol% of dimethylvinylsiloxy units, 90.000 mol% of dimethylsiloxane units, 10 parts by mass of linear dimethylpolysiloxane crude rubber having an average degree of polymerization of about 8,000, consisting of 9.975 mol% of methylvinylsiloxane units and 0.025 mol% of dimethylvinylsiloxy units, and 99.975 mol% of dimethylsiloxane units , 0.0125 mol% of dimethylhydroxysiloxy units, and 0.0125 mol% of dimethylvinylsiloxy units. 0.1 parts by mass of the nitrogen atom-containing organosilicon compound D1, 25 parts by mass of fumed silica having a BET specific surface area of 200 m ² /g (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.), and having both terminal silanol groups Then, 4 parts by mass of dimethylpolysiloxane having an average degree of polymerization of 4 and a viscosity of 15 mPa s at 25°C was added, and the mixture was heated at 170°C for 2 hours while being mixed with a kneader, to prepare a base compound (1). . This compound was used to evaluate plasticity. Table 1 shows the results.
With respect to 100 parts by mass of the above compound (1), methyl hydrogen polysiloxane having an average of 20 SiH groups in the side chain as a curing agent (degree of polymerization 38, SiH group is 0.0074 mol / g trimethylsiloxy group blocking at both ends 2 parts by mass of dimethylsiloxane/methylhydrogensiloxane copolymer), 0.05 parts by mass of ethynylcyclohexanol as a reaction control agent, and 0.1 part by mass of a platinum catalyst (Pt concentration of 1% by mass) were added using a double roll. After uniformly mixing to produce a crude rubber-like silicone rubber composition, the composition was press-cured at 120° C. and 70 kgf/cm ² for 10 minutes to form a 2 mm thick sheet. Next, the produced sheet was post-cured in an oven at 200° C. for 4 hours, and the hardness was measured. Table 1 shows the results.

[Example 2]
A base compound (2) was prepared in the same manner as in Example 1, except that the amount of the nitrogen atom-containing organosilicon compound D1 was changed to 0.2 parts by mass. This compound was used to evaluate plasticity. Table 1 shows the results.
With respect to 100 parts by mass of the compound (2), a methyl hydrogen polysiloxane having an average of 20 SiH groups in the side chain as a curing agent (degree of polymerization 38, SiH group is 0.0074 mol / g of trimethylsiloxy group blocking at both ends 2 parts by mass of dimethylsiloxane/methylhydrogensiloxane copolymer), 0.05 parts by mass of ethynylcyclohexanol as a reaction control agent, and 0.1 part by mass of a platinum catalyst (Pt concentration of 1% by mass) were added using a double roll. After uniformly mixing to produce a crude rubber-like silicone rubber composition, the composition was press-cured at 120° C. and 70 kgf/cm ² for 10 minutes to form a 2 mm thick sheet. Next, the produced sheet was post-cured in an oven at 200° C. for 4 hours, and the hardness was measured. Table 1 shows the results.

[Example 3]
80 parts by mass of linear dimethylpolysiloxane crude rubber having an average degree of polymerization of about 8,000, consisting of 99.975 mol% of dimethylsiloxane units and 0.025 mol% of dimethylvinylsiloxy units, 90.000 mol% of dimethylsiloxane units, 10 parts by mass of linear dimethylpolysiloxane crude rubber having an average degree of polymerization of about 8,000, consisting of 9.975 mol% of methylvinylsiloxane units and 0.025 mol% of dimethylvinylsiloxy units, and 99.975 mol% of dimethylsiloxane units , 0.0125 mol% of dimethylhydroxysiloxy units, and 0.0125 mol% of dimethylvinylsiloxy units. 13 parts by mass of linear dimethylpolysiloxane crude rubber having an average degree of polymerization of about 8,000 and a BET method specific surface area of 200 m ² . / g of fumed silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) 25 parts by weight, 4 parts by weight of dimethylpolysiloxane having both terminal silanol groups, an average degree of polymerization of 4, and a viscosity of 15 mPa s at 25 ° C. was added and heated under mixing with a kneader at 170° C. for 2 hours to prepare the base compound (3).
Next, 0.01 part by mass of the nitrogen atom-containing organosilicon compound D1 was added to 100 parts by mass of the compound (3) to prepare a base compound (4). This compound was used to evaluate plasticity. Table 1 shows the results.
Next, with respect to 100 parts by mass of the base compound (4), methylhydrogenpolysiloxane having an average of 20 SiH groups in the side chain as a curing agent (degree of polymerization 38, SiH groups at both ends of 0.0074 mol / g Trimethylsiloxy group-blocked dimethylsiloxane/methylhydrogensiloxane copolymer) 2 parts by weight, ethynylcyclohexanol 0.05 parts by weight as a reaction control agent, and platinum catalyst (Pt concentration 1% by weight) 0.1 parts by weight, two rolls and mixed uniformly to produce a raw rubber-like silicone rubber composition, which was then press cured at 120° C. and 70 kgf/cm ² for 10 minutes to form a 2 mm thick sheet. Next, the produced sheet was post-cured in an oven at 200° C. for 4 hours, and the hardness was measured. Table 1 shows the results.

[Comparative Example 1]
In Example 1, a base compound (5) was prepared in the same manner as in Example 1 except that the nitrogen atom-containing organosilicon compound D1 was not added. The plasticity and the hardness of the cured silicone rubber were measured. These results are shown in Table 1.

[Comparative Example 2]
93 parts by mass of straight-chain dimethylpolysiloxane crude rubber having an average degree of polymerization of about 8,000 consisting of 99.975 mol% of dimethylsiloxane units and 0.025 mol% of dimethylvinylsiloxy units, 90.000 mol% of dimethylsiloxane units, 10 parts by mass of a straight-chain dimethylpolysiloxane crude rubber having an average degree of polymerization of about 8,000 consisting of 9.975 mol% of methylvinylsiloxane units and 0.025 mol% of dimethylvinylsiloxy units, represented by the above formula (D1); 0.2 parts by mass of nitrogen atom-containing organosilicon compound D1, 25 parts by mass of fumed silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) having a BET specific surface area of 200 m ² /g, and silanol groups at both ends , 4 parts by mass of dimethylpolysiloxane having an average degree of polymerization of 4 and a viscosity of 15 mPa·s at 25°C was added and heated at 170°C for 2 hours while being mixed with a kneader to prepare a base compound (6). This compound was used to evaluate plasticity. Table 1 shows the results.
With respect to 100 parts by mass of the compound (6), methylhydrogenpolysiloxane having an average of 20 SiH groups in the side chain as a curing agent (degree of polymerization 38, SiH group is 0.0074 mol / g trimethylsiloxy group blocking at both ends 2 parts by mass of dimethylsiloxane/methylhydrogensiloxane copolymer), 0.05 parts by mass of ethynylcyclohexanol as a reaction control agent, and 0.1 part by mass of a platinum catalyst (Pt concentration of 1% by mass) were added using a double roll. After uniformly mixing to produce a crude rubber-like silicone rubber composition, the composition was press-cured at 120° C. and 70 kgf/cm ² for 10 minutes to form a 2 mm thick sheet. Next, the produced sheet was post-cured in an oven at 200° C. for 4 hours, and the hardness was measured. Table 1 shows the results.

[Example 4]
80 parts by mass of linear dimethylpolysiloxane crude rubber having an average degree of polymerization of about 8,000, consisting of 99.850 mol% of dimethylsiloxane units, 0.125 mol% of methylvinylsiloxane units, and 0.025 mol% of dimethylvinylsiloxy units , 99.975 mol% of dimethylsiloxane units, 0.0125 mol% of dimethylhydroxysiloxy units, and 0.0125 mol% of dimethylvinylsiloxy units. parts, 0.08 parts by mass of a nitrogen atom-containing organosilicon compound D2 represented by the following formula (D2), and fumed silica having a BET specific surface area of 200 m ² /g (Aerosil R974, manufactured by Nippon Aerosil Co., Ltd.) 30 The base compound (7) was prepared after adding parts by weight and heating under mixing with a kneader at 170° C. for 2 hours. This compound was used to evaluate plasticity. Table 2 shows the results.
To 100 parts by mass of the compound (7), 0.4 parts by mass of 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane as a curing agent is added with a double roll and uniformly After mixing to produce a raw rubber-like silicone rubber composition, the composition was press cured for 10 minutes at 165° C. and 70 kgf/cm ² to form a 2 mm thick sheet. Next, the produced sheet was post-cured in an oven at 200° C. for 4 hours, and the hardness was measured. Table 2 shows the results.

[Example 5]
A base compound (8) was prepared in the same manner as in Example 4, except that the nitrogen atom-containing organosilicon compound D2 was changed to 0.16 parts by mass. This compound was used to evaluate plasticity. Table 2 shows the results.
To 100 parts by mass of the compound (8), 0.4 parts by mass of 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane as a curing agent is added with a double roll and uniformly After mixing to produce a raw rubber-like silicone rubber composition, the composition was press cured for 10 minutes at 165° C. and 70 kgf/cm ² to form a 2 mm thick sheet. Next, the produced sheet was post-cured in an oven at 200° C. for 4 hours, and the hardness was measured. Table 2 shows the results.

[Example 6]
80 parts by mass of linear dimethylpolysiloxane crude rubber having an average degree of polymerization of about 8,000, consisting of 99.850 mol% of dimethylsiloxane units, 0.125 mol% of methylvinylsiloxane units, and 0.025 mol% of dimethylvinylsiloxy units , 99.975 mol% of dimethylsiloxane units, 0.0125 mol% of dimethylhydroxysiloxy units, and 0.0125 mol% of dimethylvinylsiloxy units. 30 parts by mass of fumed silica having a BET specific surface area of 200 m ² /g (Aerosil R974, manufactured by Nippon Aerosil Co., Ltd.) was added and heated at 170° C. for 2 hours while being mixed with a kneader, and then the base compound was prepared. (9) was prepared.
Next, 0.01 part by mass of the nitrogen atom-containing organosilicon compound D2 was added to 100 parts by mass of the compound (9) to prepare a base compound (10). This compound was used to evaluate plasticity. Table 2 shows the results.
Next, 0.4 parts by mass of 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane as a curing agent was added to 100 parts by mass of the compound (10) using a double roll. After uniformly mixing to produce a crude rubber-like silicone rubber composition, the composition was press-cured at 165° C. and 70 kgf/cm ² for 10 minutes to form a 2 mm thick sheet. Next, the produced sheet was post-cured in an oven at 200° C. for 4 hours, and the hardness was measured. Table 2 shows the results.

[Comparative Example 3]
In Example 4, a base compound (11) was prepared in the same manner as in Example 4 except that the nitrogen atom-containing organosilicon compound D2 was not added. The plasticity and the hardness of the cured silicone rubber were measured. These results are shown in Table 2.

Claims (7)

(A) the following average composition formula (1)
R1aSiO(4- _{a )/2} ( ¹ )
(In the formula, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and a is a positive number of 1.95 to 2.05.)
100 parts by mass of organopolysiloxane having a degree of polymerization of 100 or more represented by
(B) Formula (2) below

(In the formula, R ² is an aliphatic unsaturated group, R ³ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and n is a positive number of 100 or more.)
1 to 50 parts by mass of organopolysiloxane represented by
(C) Reinforcing silica having a specific surface area of 50 m ² /g or more as determined by the BET adsorption method
5 to 100 parts by mass,
(D) A nitrogen atom-containing organosilicon compound having an average of two or more groups per molecule, selected from substituted aminoxy groups represented by the following formulas (3) and (4), bonded to silicon atoms: 0.001 to 15 parts by mass,

(In the formula, R ⁴ and R ⁵ are the same or different monovalent hydrocarbon groups, and R ⁶ is a divalent organic group.)
(E) Curing agent A millable type silicone rubber composition characterized by containing an effective amount. 2. The millable type silicone rubber composition according to claim 1, wherein component (D) is one or more selected from organosilicon compounds represented by the following formulas (5) to (8).

(Wherein, R ⁷ is the same or different substituted or unsubstituted monovalent hydrocarbon group, OY is a group represented by the above formula (3) or (4), b is 0, 1 or 2, c is 0 or a positive number of 10 or less, l is a positive number of 1 to 20, m is a positive number of 2 to 20, and l+m is a positive number of 3 or more, R' is R ⁷ or OY, p and q are each independently a positive number of 0 or 100 or less, and when q is 0 or more and less than 1, two R' are OY, and when q is 1 or more and less than 2, at least one of R' is OY. Q is a divalent hydrocarbon group having 1 to 20 carbon atoms.) 3. The millable type silicone rubber composition according to claim 1 or 2, wherein the curing agent of component (E) is an addition reaction curing type comprising a combination of an organohydrogenpolysiloxane and a hydrosilylation catalyst. 3. The millable type silicone rubber composition according to claim 1, wherein the curing agent of component (E) is an organic peroxide. 3. The millable type silicone rubber composition according to claim 1, wherein the curing agent (E) is a combination of an organohydrogenpolysiloxane and a hydrosilylation catalyst and an organic peroxide. A cured silicone rubber obtained by curing the millable type silicone rubber composition according to any one of claims 1 to 5 . (A) the following average composition formula (1)
R. ¹ _a SiO _(4-a)/2 (1)
(In the formula, R ¹ are the same or different unsubstituted or substituted monovalent hydrocarbon groups, and a is a positive number of 1.95 to 2.05. )
100 parts by mass of organopolysiloxane having a degree of polymerization of 100 or more represented by
(B) Formula (2) below

(In the formula, R ² is an aliphatically unsaturated group, and R ³ are the same or different unsubstituted or substituted monovalent hydrocarbon groups, and n is a positive number of 100 or more. )
1 to 50 parts by mass of organopolysiloxane represented by
(C) The specific surface area by the BET adsorption method is 50m ² / g or more of reinforcing silica
5 to 100 parts by mass,
(D) A nitrogen atom-containing organosilicon compound having an average of two or more groups per molecule, selected from substituted aminoxy groups represented by the following formulas (3) and (4), bonded to silicon atoms: 0.001 to 15 parts by mass,

(In the formula, R ^Four and R ^Five are the same or different monovalent hydrocarbon groups. R. ⁶ is a divalent organic group. )
A silicone rubber compound for a millable type silicone rubber composition containing