JP2013129720A - Imide-modified silicone elastomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imide-modified silicone elastomer excellent in heat resistance.SOLUTION: The imide-modified silicone elastomer is represented by formula (I), wherein Ris a divalent organic group containing an aromatic ring or an aliphatic ring; Rand Rare identical or different, and are a divalent organic group; Rto Rare identical or different, and are hydrogen, an alkyl group or a phenyl group; Ris a tetravalent organic group containing ≥4 carbon atoms; n is an integer of 1 to 160; and m is an integer of 1 to 100.

Description

  The present invention relates to an elastomer having an imide component and a siloxane component.

  Conventionally, an imide-modified elastomer is known as an elastomer that is flexible and excellent in strength, heat resistance, and the like (see, for example, Patent Document 1). The imide-modified elastomer exhibits flexibility by the contained elastomer component, and exhibits strength and heat resistance by the contained imide component.

  However, in the conventional imide-modified elastomer as described in Patent Document 1, since the elastomer component is composed of olefin, the olefin is likely to be thermally deteriorated under a high temperature atmosphere, and the heat resistance is not sufficient.

  On the other hand, the present applicant has previously developed an imide-modified silicone elastomer as described in Patent Document 2 as an imide-modified elastomer having excellent heat resistance. Although this imide-modified silicone elastomer contains a siloxane component and is relatively excellent in heat resistance, the elastomer component is composed of urethane, so that there is a problem that urethane deteriorates due to thermal divergence in a high temperature atmosphere. However, the current situation is that sufficient heat resistance is not always obtained.

JP-A-11-106507 JP 2008-231155 A

  An object of the present invention is to provide an imide-modified silicone elastomer having excellent heat resistance.

［式中、Ｒ₁は、芳香族環または脂肪族環を含む２価の有機基を示す。Ｒ₂およびＲ₃は、それぞれ同一または異なる基であって、２価の有機基を示す。Ｒ₄〜Ｒ₇は、それぞれ同一または異なる基であって、水素、アルキル基、フェニル基を示す。Ｒ₈は、４個以上の炭素を含む４価の有機基を示す。ｎは１〜１６０の整数を示す。ｍは１〜１００の整数を示す。］で表されることを特徴とするイミド変性シリコーンエラストマー。
（２）ジイソシアナートを、シロキサン結合を有するジアミン化合物でウレア結合により鎖延長したポリシロキサン−ウレア化合物と、テトラカルボン酸二無水物と、を混合して反応させることによって得られるポリアミック酸を架橋した後にイミド化した共重合体である前記（１）記載のイミド変性シリコーンエラストマー。
（３）前記シロキサン結合を有するジアミン化合物とともに、シロキサン結合を有さないジアミン化合物をさらに添加する前記（２）記載のイミド変性シリコーンエラストマー。
（４）イミド分率が５〜８０重量％である前記（１）〜（３）のいずれかに記載のイミド変性シリコーンエラストマー。
（５）イミド分率が１０〜３０重量％である前記（１）〜（４）のいずれかに記載のイミド変性シリコーンエラストマー。
（６）前記（１）〜（５）のいずれかに記載のイミド変性シリコーンエラストマーからなる成形品。
（７）ガスケットである前記（６）記載の成形品。 As a result of intensive studies to solve the above-described problems, the present inventors have found a solution means having the following configuration and have completed the present invention.
(1) General formula (I):

[Wherein, R ₁ represents a divalent organic group containing an aromatic ring or an aliphatic ring. R ₂ and R ₃ are the same or different groups and represent a divalent organic group. R _{4 to} R ₇ are the same or different groups, and each represents hydrogen, an alkyl group, or a phenyl group. R ₈ represents a tetravalent organic group containing 4 or more carbons. n represents an integer of 1 to 160. m shows the integer of 1-100. ] The imide modified silicone elastomer characterized by the above-mentioned.
(2) A polyamic acid obtained by mixing and reacting a polysiloxane-urea compound obtained by chain-extending a diisocyanate with a diamine compound having a siloxane bond by a urea bond and tetracarboxylic dianhydride is crosslinked. The imide-modified silicone elastomer according to (1), wherein the imide-modified silicone elastomer is a copolymer that has been imidized after.
(3) The imide-modified silicone elastomer according to (2), wherein a diamine compound not having a siloxane bond is further added together with the diamine compound having a siloxane bond.
(4) The imide-modified silicone elastomer according to any one of (1) to (3), wherein the imide fraction is 5 to 80% by weight.
(5) The imide-modified silicone elastomer according to any one of (1) to (4), wherein the imide fraction is 10 to 30% by weight.
(6) A molded article comprising the imide-modified silicone elastomer according to any one of (1) to (5).
(7) The molded product according to (6), which is a gasket.

  In addition, the “imide-modified silicone elastomer” in the present invention means an elastomer having an imide component and a siloxane component, and is a concept including a resin depending on a ratio (imide fraction) of the imide component.

  According to the present invention, there is no urethane or olefin component in the main chain, and therefore there is no problem of a decrease in heat resistance due to thermal degradation of these components, and since the main chain has a siloxane component, the effect of excellent heat resistance There is.

  Hereinafter, an imide-modified silicone elastomer according to an embodiment of the present invention will be described. The imide-modified silicone elastomer of the present embodiment is an imide-modified silicone elastomer represented by the above general formula (I) (hereinafter sometimes referred to as “imide-modified silicone elastomer (I)”).

In the general formula (I), R ₁ represents a divalent organic group containing an aromatic ring or an aliphatic ring, and is chain-extended with a urea bond by the diamine compound (b) according to, for example, the reaction process formula (A) described later. In the diisocyanate (a), a residue other than the isocyanato group (—NCO) is exemplified.

Examples of R _{2 to} R ₇ include residues other than the amino group (—NH ₂ ) in the diamine compound (b) described above. Specifically, among R _{2 to} R ₇ , R ₂ and R ₃ are the same or different groups, each representing a divalent organic group, for example, an alkylene group, a group: —C ₆ H ₄ COO -Etc. are mentioned. Examples of the alkylene group include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, an isobutylene group, an s-butylene group, a t-butylene group, a pentylene group, an isopentylene group, a neopentylene group, and a hexylene group. C1-C6 alkylene groups, such as these, are mentioned. R ₂ and R ₃ are bonded to an amino group (—NH ₂ ) in the diamine compound (b) described above. When R ₂ and R ₃ are a group: —C ₆ H ₄ COO—, the bonding state between this group and an amino group is H ₂ N—C ₆ H ₄ COO—.

R _{4 to} R ₇ are the same or different groups, and each represents hydrogen, an alkyl group, or a phenyl group. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and a hexyl group. And a linear or branched alkyl group having 1 to 10 carbon atoms. n represents an integer of 1 to 160, preferably 5 to 100.

On the other hand, R ₈ represents a tetravalent organic group containing 4 or more carbon atoms, and for example, an aromatic tetramer having 6 to 18 carbon atoms capable of introducing an imide unit into a urea bond portion according to a reaction process formula (B) described later. Examples include a residue of at least one tetracarboxylic dianhydride (d) selected from carboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides having 4 to 6 carbon atoms.

  m represents an integer of 1 to 100, preferably 2 to 80.

  The imide-modified silicone elastomer (I) is obtained by mixing and reacting a disiloxane with a polysiloxane-urea compound chain-extended by a urea bond with a diamine compound having a siloxane bond and a tetracarboxylic dianhydride. A copolymer obtained by cross-linking the resulting polyamic acid and then imidizing is preferable. The imide-modified silicone elastomer (I) can be produced, for example, through reaction process formulas (A) to (C) as shown below.

［式中、Ｒ₁〜Ｒ₇，ｎ，ｍは、上述したものと同じである。］ [Reaction process formula (A)]

[Wherein R _{1 to} R ₇ , n, m are the same as described above. ]

(Synthesis of polysiloxane-urea compound (c))
First, according to the reaction process formula (A), the diisocyanate (a) is chain-extended by a urea bond with a diamine compound (b) having a siloxane bond to obtain a polysiloxane-urea compound (c). Since the imide-modified silicone elastomer (I) contains a siloxane component derived from the diamine compound (b) as an elastomer component, the imide-modified silicone elastomer (I) is superior in heat resistance to a conventional imide-modified elastomer containing an olefin component or a urethane component as an elastomer component.

  Examples of the diisocyanate (a) include 2,4-tolylene diisocyanate (TDI), 2,6-tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), polymeric MDI ( Cr.MDI), dianisidine diisocyanate (DADL), diphenyl ether diisocyanate (PEDI), pitirylene diisocyanate (TODI), naphthalene diisocyanate (NDI), hexamethylene diisocyanate (HMDI), isophorone diisocyanate Nart (IPDI), lysine diisocyanate methyl ester (LDI), metaxylylene diisocyanate (MXDI), 2,2,4-trimethylhexamethylene diisocyanate (TMDI), 2,4,4-trimethylhexamethylenedi Cyanate (TMDI), dimer acid diisocyanate (DDI), isopropylidenebis (4-cyclohexyl isocyanate) (IPCI), cyclohexylmethane diisocyanate (hydrogenated MDI), methylcyclohexane diisocyanate (hydrogenated TDI), TDI dimer (TT) etc. are mentioned, These may mix and use 1 type, or 2 or more types, It is preferable to use what was distilled under reduced pressure.

  As a weight average molecular weight of a diamine compound (b), it is preferable that it is 500-15,000, and it is more preferable that it is 500-5,000. The weight average molecular weight is a value obtained by measuring the diamine compound (b) by gel permeation chromatography (GPC) and converting the obtained measurement value to polystyrene.

In the reaction, diisocyanate (a) and diamine compound (b) are mixed in an equimolar amount, preferably an NCO / NH ₂ ratio of about 1.0, and then an inert gas atmosphere such as argon gas or nitrogen gas. Preferably it is carried out below. A suitable reaction temperature is room temperature (23 ° C.) to about 100 ° C., and a suitable reaction time is about 2 to 30 hours.

  The reaction may be performed in a solvent or without a solvent. Examples of a solvent that can be used when the reaction is carried out in a solvent include N, N-dimethylacetamide, N-methyl-2-pyrrolidone (NMP), N-hexyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidone. These may be used singly or in combination of two or more, and it is preferable to use a dehydrated one.

  The weight average molecular weight of the resulting polysiloxane-urea compound (c) is preferably 5,000 to 1,000,000, and more preferably 10,000 to 500,000. The weight average molecular weight is a value obtained by measuring the polysiloxane-urea compound (c) by GPC and converting the obtained measurement value into polystyrene.

［式中、Ｒ₁〜Ｒ₈，ｎ，ｍは、上述したものと同じである。］ [Reaction process formula (B)]

[Wherein R _{1 to} R ₈ , n, m are the same as those described above. ]

(Synthesis of polyamic acid (e))
Next, according to the reaction process formula (B), the polysiloxane-urea compound (c) and the tetracarboxylic dianhydride (d) are mixed and reacted, and the polyamic acid (e) as the imide precursor is reacted. obtain.

  Examples of the tetracarboxylic dianhydride (d) include pyromellitic anhydride (PMDA), oxydiphthalic dianhydride (ODPA), biphenyl-3,4,3 ′, 4′-tetracarboxylic dianhydride (BPDA). ), Benzophenone-3,4,3 ′, 4′-tetracarboxylic dianhydride (BTDA), diphenylsulfone-3,4,3 ′, 4′-tetracarboxylic dianhydride (DSDA), 4,4 6 carbon atoms such as '-(2,2-hexafluoroisopropylidene) diphthalic dianhydride (6FDA), m (p) -terphenyl-3,4,3', 4'-tetracarboxylic dianhydride To 18 aromatic tetracarboxylic dianhydrides; cyclobutane-1,2,3,4-tetracarboxylic dianhydride, 1-carboxymethyl-2,3,5-cyclopentanetricarboxylic acid-2, : 3,5 dianhydride alicyclic tetracarboxylic dianhydride of 4-6 carbon atoms such as, and the like. These may be used alone or in combination.

  The reaction is preferably carried out in an inert gas atmosphere such as argon gas or nitrogen gas after the polysiloxane-urea compound (c) and the tetracarboxylic dianhydride (d) are mixed at a predetermined ratio. The polysiloxane-urea compound (c) and the tetracarboxylic dianhydride (d) are mixed so that the tetracarboxylic dianhydride (d) is a diisocyanate (a) in the above reaction process formula (A). It is preferable to carry out in such a ratio that it is about twice the equivalent.

  As reaction temperature, it is preferable that it is 100-300 degreeC, It is more preferable that it is 135-200 degreeC, It is further more preferable that it is 150-170 degreeC. The reaction time is suitably about 1 hour to 10 hours. The reaction may be performed in a solvent or without a solvent. Examples of the solvent that can be used when the reaction is performed in a solvent include the same solvents as those exemplified in the reaction process formula (A).

［式中、Ｒ₁〜Ｒ₈，ｎ，ｍは、上述したものと同じである。］ [Reaction process formula (C)]

[Wherein R _{1 to} R ₈ , n, m are the same as those described above. ]

(Synthesis of imide-modified silicone elastomer (I))
Finally, the polyamic acid (e) is crosslinked with a crosslinking agent and then imidized to obtain an imide-modified silicone elastomer (I). Examples of the crosslinking agent include peroxides (peroxides) and dicumyl peroxide. The addition amount of the crosslinking agent is preferably about 5 to 15 parts by weight with respect to 100 parts by weight of the polyamic acid (e) in terms of solid content.

  The imidization (dehydration condensation reaction) may be performed under the condition that the polyamic acid (e) is not thermally decomposed. The reaction temperature is about 150 to 250 ° C., and the reaction time is about 90 to 150 minutes. . Prior to imidization, the solvent may be volatilized by heat-treating the polyamic acid (e) under conditions of about 70 to 200 ° C. and about 20 minutes to 3 hours.

  The weight average molecular weight of the imide-modified silicone elastomer (I) is preferably 10,000 to 1,000,000, more preferably 15,000 to 150,000, and 20,000 to 100,000. More preferably. If the weight average molecular weight of the imide-modified silicone elastomer (I) is too small, the strength may decrease. Moreover, when the weight average molecular weight of imide modified silicone elastomer (I) is too large, there exists a possibility that a softness | flexibility may fall. The weight average molecular weight is a value derived from a value obtained by measuring the polyamic acid (e) by GPC and converting the obtained measurement value into polystyrene. The reason why the polyamic acid (e), not the imide-modified silicone elastomer (I), is measured by GPC is that the imide-modified silicone elastomer (I) is insoluble in the GPC measurement solvent.

  The ratio of the imide component in the imide-modified silicone elastomer (I), that is, the imide fraction, is preferably 5 to 80% by weight, and more preferably 10 to 30% by weight. Thereby, the ratio of the imide component in the imide-modified silicone elastomer (I) is optimized, and the flexibility, strength and heat resistance can be improved in a balanced manner.

  The imide fraction is a value calculated from the amounts of raw materials, that is, diisocyanate (a), diamine compound (b) and tetracarboxylic dianhydride (d), and is calculated from the following formula (α). Value.

The elastic modulus of the imide-modified silicone elastomer (I) is preferably about 1 × 10 ³ to 1 × 10 ⁹ Pa. The elastic modulus can be adjusted to a desired value by adjusting the imide fraction described above. As will be described later, the elastic modulus is a value of the storage elastic modulus E ′ at 50 ° C. obtained by measurement using a dynamic viscoelasticity measuring device.

  The above-mentioned imide-modified silicone elastomer (I) can be used after being molded into a desired molded product. Molded products include, for example, sheets, films, tubes, hoses, roll gears, packing materials, soundproof materials, vibration proof materials, boots, gaskets, belts, belt laminate products, coating materials, pervaporation separation membranes, optical nonlinear materials , Elastic fibers, piezoelectric elements, actuators, other various automobile parts, industrial machine parts, sporting goods, and the like, but are not limited thereto. When the imide-modified silicone elastomer (I) is molded into the above-described molded product, it is preferable to imidize after molding in the state of polyamic acid (e) for efficient molding.

  As mentioned above, although preferred embodiment concerning this invention was described, it cannot be overemphasized that this invention can be made arbitrary, unless it deviates from the summary of this invention, and is not limited to embodiment mentioned above.

  For example, in the above-described embodiment, the diamine compound (b) having a siloxane bond is added as the diamine compound, but in addition to the diamine compound (b), a diamine compound having no siloxane bond (hereinafter referred to as “non- A siloxane diamine compound (f) ”may be further added. Thereby, adjustment of an imide fraction can be performed comparatively easily and it becomes easy to optimize the physical property balance of imide modified silicone elastomer (I).

  Examples of the non-siloxane diamine compound (f) include 1,4-diaminobenzene (alias: p-phenylenediamine, abbreviation: PPD), 1,3-diaminobenzene (alias: m-phenylenediamine, abbreviation: MPD), 2 , 4-diaminotoluene (alias: 2,4-toluenediamine, abbreviation: 2,4-TDA), 4,4′-diaminodiphenylmethane (alias: 4,4′-methylenedianiline, abbreviation: MDA), 4, 4'-diaminodiphenyl ether (alias: 4,4'-oxydianiline, abbreviation: ODA, DPE), 3,4'-diaminodiphenyl ether (alias: 3,4'-oxydianiline, abbreviation: 3,4'-) DPE), 3,3′-dimethyl-4,4′-diaminobiphenyl (also known as o-tolidine, abbreviation: TB), 2,2′-dimethyl-4,4 -Diaminobiphenyl (alias: m-tolidine, abbreviation: m-TB), 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (abbreviation: TFMB), 3,7-diamino-dimethyldibenzo Thiophene-5,5-dioxide (also known as o-tolidine sulfone, abbreviation: TSN), 4,4′-diaminobenzophenone, 3,3′-diaminobenzophenone, 4,4′-bis (4-aminophenyl) sulfide ( Alias: 4,4′-thiodianiline, abbreviation: ASD), 4,4′-diaminodiphenyl sulfone (alias: 4,4′-sulfonyldianiline, abbreviation: ASN), 4,4′-diaminobenzanilide (abbreviation: DABA), 1, n-bis (4-aminophenoxy) alkane (n = 3,4,5, abbreviation: DAnMG), 1,3-bis (4- Minophenoxy) -2,2-dimethylpropane (abbreviation: DANPG), 1,2-bis [2- (4-aminophenoxy) ethoxy] ethane (abbreviation: DA3EG), 9,9-bis (4-aminophenyl) Fluorene (abbreviation: FDA), 5 (6) -amino-1- (4-aminomethyl) -1,3,3-trimethylindane, 1,4-bis (4-aminophenoxy) benzene (abbreviation: TPE-Q) ), 1,3-bis (4-aminophenoxy) benzene (alias: resorcinoxydianiline, abbreviation: TPE-R), 1,3-bis (3-aminophenoxy) benzene (abbreviation: APB), 4,4 '-Bis (4-aminophenoxy) biphenyl (abbreviation: BAPB), 4,4'-bis (3-aminophenoxy) biphenyl, 2,2-bis (4-aminophenoxyphe) Nyl) propane (abbreviation: BAPP), bis [4- (4-aminophenoxy) phenyl] sulfone (abbreviation: BAPS), bis [4- (3-aminophenoxy) phenyl] sulfone (abbreviation: BAPS-M), 2 , 2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane (abbreviation: HFBAPP), 3,3′-dicarboxy-4,4′-diaminodiphenylmethane (abbreviation: MBAA), 4,6-dihydroxy -1,3-phenylenediamine (alias: 4,6-diaminoresorcin), 3,3′-dihydroxy-4,4′-diaminobiphenyl (alias: 3,3′-dihydroxybenzidine, abbreviation: HAB), 3, 6-27 carbon atoms such as 3 ′, 4,4′-tetraaminobiphenyl (also known as: 3,3′-diaminobenzidine, abbreviation: TAB) Aromatic diamine compounds; 1,6-hexamethylenediamine (HMDA), 1,8-octamethylenediamine (OMDA), 1,9-nonamethylenediamine, 1,12-dodecamethylenediamine (DMDA), 1-amino- C6-C24 aliphatic or alicyclic diamine compounds such as 3-aminomethyl-3,5,5-trimethylcyclohexane (also known as isophoronediamine), 4,4′-dicyclohexylmethanediamine, cyclohexanediamine, and the like. These may be used alone or in combination of two or more.

  The non-siloxane diamine compound (f) may be added together with the diamine compound (b) in the above-described reaction process formula (A). Moreover, the imide fraction in the case of adding a non-siloxane diamine compound (f) can be calculated from the following formula (β). Other configurations are the same as those of the imide-modified silicone elastomer (I) according to the embodiment described above.

  EXAMPLES Hereinafter, although a synthesis example and an Example are given and this invention is demonstrated in detail, this invention is not limited only to the following synthesis examples and Examples.

The imide-modified silicone elastomers used in the following examples are the following three types.
<Synthesis Example 1>
Imide-modified silicone elastomers were synthesized according to the reaction process formulas (A) to (C) described above.
(Synthesis of polysiloxane-urea compound)
First, 4,4′-diphenylmethane diisocyanate (MDI) [manufactured by Nippon Polyurethane Industry Co., Ltd.] was distilled under reduced pressure. Next, as a diamine compound having a siloxane bond, R ₂ and R ₃ in the general formula (I) both represent an n-propylene group, R _{4 to} R ₆ all represent a methyl group, and R ₇ represents phenyl. A trade name “X-22-1660B-3” manufactured by Shin-Etsu Chemical Co., Ltd., in which n represents an integer of 5 to 100, was prepared.

  17 g of MDI and 300 g of the diamine compound having a siloxane bond were respectively added to a 500 ml four-necked separable flask equipped with a stirrer and a gas introduction tube so that the ratio of the above-mentioned MDI and the diamine compound having a siloxane bond was equimolar. Further, 200 ml of dehydrated N-methyl-2-pyrrolidone (NMP) was added.

  And it stirred at 80 degreeC under argon atmosphere for 2 hours, and obtained the solution of the polysiloxane-urea compound. As a result of measuring the obtained polysiloxane-urea compound by GPC, the weight average molecular weight was 200,000 in terms of polystyrene conversion.

(Synthesis of polyamic acid)
Next, 30 g of pyromellitic anhydride (PMDA) is added to the obtained polysiloxane-urea compound solution so that the ratio thereof is twice the equivalent of MDI, and the mixture is kept at 150 ° C. for 2 hours in an argon gas atmosphere. Stirring to obtain a polyamic acid solution. 1,000 ml of methanol was added to the obtained polyamic acid solution to precipitate polyamic acid. The precipitated polyamic acid was dried in a vacuum at 80 ° C. for 14 hours to obtain a solid polyamic acid.

  5 g of a peroxide (“Die Cup 40C” manufactured by Arkema Co., Ltd.) as a crosslinking agent was added to 50 g of the obtained polyamic acid, and the kneading temperature was 100 ° C. with a mill (“Lab plast mill” manufactured by Toyo Seiki Seisakusho Co., Ltd.). The mixture was kneaded under the conditions of several 40 rpm and a kneading time of 5 minutes to obtain a kneaded product. 22 g of this kneaded product is filled in a mold having a width of 50 mm, a length of 100 mm, and a thickness of 2 mm, and pressed under conditions of a pressure of 15 MPa, a pressing temperature of 170 ° C. and a pressing time of 20 minutes to crosslink the polyamic acid and form a sheet Molded into.

  Then, the polyamic acid formed into a sheet and cross-linked is heat-treated in an oven at 200 ° C. for 2 hours (dehydration condensation reaction) to form a sheet having a thickness of 2 mm, and n in the general formula (I) Is 1 to 160, and m is 1 to 100 to obtain an imide-modified silicone elastomer (1).

About the obtained imide modified silicone elastomer (1), an imide fraction, an elastic modulus, and a weight average molecular weight were measured. The measurement results are as follows.
-Imide fraction: 14% by weight
Elastic modulus: 0.2 × 10 ⁸ Pa
-Weight average molecular weight: 85,000

  In addition, the imide fraction was calculated from the formula (α) described above. The elastic modulus is 50 ° C. in a temperature rising process of 10 Hz, 5 ° C./min, −100 to 400 ° C. using a dynamic viscoelasticity measuring device “DMS 6100” manufactured by Seiko Instruments Inc. The storage elastic modulus E ′ of was measured. The weight average molecular weight was derived from a value obtained by measuring polyamic acid by GPC and converting the obtained measurement value into polystyrene.

Further, the imide-modified silicone elastomer (1), a result of measuring the IR spectrum at ATR method, 1780 cm ^-1, absorption derived from the imide ring to 1720 cm ^-1 and 1380 cm ^-1 were observed.

<Synthesis Example 2>
First, except that 17 g of MDI and 240 g of a diamine compound having a siloxane bond were added and 2.7 g of 4,4′-diaminodiphenylmethane (MDA), which is a non-siloxane diamine compound, was added together with the diamine compound having a siloxane bond. In the same manner as in Example 1, a polysiloxane-urea compound having a weight average molecular weight of 180,000 was obtained.

  Next, a solid polyamic acid was obtained in the same manner as in Synthesis Example 1 except that 30 g of PMDA was added to the obtained polysiloxane-urea compound solution, and this polyamic acid was crosslinked and formed into a sheet. The imide-modified silicone elastomer (2) was obtained by molding and heat-treating to form a sheet having a thickness of 2 mm, wherein n is 1 to 160 in the general formula (I) and m is 1 to 100.

For the obtained imide-modified silicone elastomer (2), the imide fraction was calculated from the formula (β) described above, and the modulus of elasticity and the weight average molecular weight were measured in the same manner as in Synthesis Example 1. The measurement results are as follows.
・ Imid fraction: 18% by weight
Elastic modulus: 0.5 × 10 ⁸ Pa
-Weight average molecular weight: 70,000

Further, the imide-modified silicone elastomer (2), a result of measuring the IR spectrum at ATR method, 1780 cm ^-1, absorption derived from the imide ring to 1720 cm ^-1 and 1380 cm ^-1 were observed.

<Synthesis Example 3>
First, the weight average molecular weight was 200,000 as in Synthesis Example 1 except that 17 g of MDI and 180 g of the diamine compound having a siloxane bond were added, and 5.4 g of MDA was added together with the diamine compound having the siloxane bond. A polysiloxane-urea compound was obtained.

  Next, a solid polyamic acid was obtained in the same manner as in Synthesis Example 1 except that 30 g of PMDA was added to the obtained polysiloxane-urea compound solution, and this polyamic acid was crosslinked and formed into a sheet. The imide-modified silicone elastomer (3) was obtained by molding and heat-treating to form a sheet having a thickness of 2 mm, wherein n is 1 to 160 in the general formula (I) and m is 1 to 100.

For the obtained imide-modified silicone elastomer (3), the imide fraction, elastic modulus and weight average molecular weight were measured in the same manner as in Synthesis Examples 1 and 2. The measurement results are as follows.
-Imide fraction: 23% by weight
・ Elastic modulus: 1 × 10 ⁸ Pa
-Weight average molecular weight: 80,000

Further, the imide-modified silicone elastomer (3), a result of measuring an IR spectrum by ATR method, 1780 cm ^-1, absorption derived from the imide ring to 1720 cm ^-1 and 1380 cm ^-1 were observed.

[Examples 1 to 3]
The imide-modified silicone elastomers (1) to (3) obtained in Synthesis Examples 1 to 3 were subjected to a gasket test and a heat aging test. Each test method is shown below, and the results are shown in Table 1.

<Gasket test method>
First, a sheet-like imide-modified silicone elastomer was molded into a gasket shape to obtain three test pieces. Next, three test pieces obtained and three corrugated gasket plates in a side view were alternately laminated to obtain a test piece laminate. The test piece laminate is sandwiched between stainless steel (SUS) plates, and the SUS plate is clamped from above and below with bolts and nuts. % To be compressed. This compressed specimen laminate was exposed to a high temperature environment and a high temperature and high humidity environment, respectively, and the thickness retention (%) and appearance were evaluated.

The high temperature environment and the high temperature and high humidity environment are as follows.
(High temperature environment)
The compressed specimen laminate was left in an oven at 200 ° C. for 250 hours. In this high temperature environment, the specimen is exposed to dry air.

(High temperature and high humidity environment)
First, the test piece laminate in a compressed state was accommodated and sealed in a sealed container containing water so as not to be immersed in water. Next, this sealed container was left in an oven at 200 ° C. for 250 hours. In this high temperature and high humidity environment, the test piece is exposed to saturated water vapor.

The thickness retention (%) was calculated by applying the initial thickness (T1) before compression and the thickness (T2) after the test to the formula: (T2 / T1) · 100. The appearance after the test was evaluated according to the following criteria.
○: No cracking occurred in the test piece.
X: Cracks occurred in the test piece.

<Method of heat aging test>
A sheet-like imide-modified silicone elastomer was punched out with a No. 3 dumbbell and subjected to a tensile test in accordance with JIS K6257 to measure the breaking strength (Tb) before thermal aging. In addition, a sheet-like imide-modified silicone elastomer was punched out with a No. 3 dumbbell and was heat-aged at 200 ° C. for 96 hours in a gear oven “GPH-101” manufactured by Espec Co., Ltd. A tensile test was performed in the same manner as the measurement of the breaking strength (Tb), and the breaking strength (Tb) after heat aging was measured.

[Comparative Example 1]
A gasket test and a heat aging test were conducted in the same manner as in Examples 1 to 3 on a commercially available silicone rubber in the form of a sheet having a thickness of 2 mm. The results are shown in Table 1. In addition, the used silicone rubber is as follows.
・ Silicone rubber: Trade name “SH75UN” manufactured by Toray Dow Corning Co., Ltd.

[Comparative Example 2]
A gasket test and a heat aging test were performed in the same manner as in Examples 1 to 3 on a commercially available fluororubber made of Tigers Polymer Co., Ltd. in the form of a sheet having a thickness of 2 mm. The results are shown in Table 1.

[Comparative Example 3]
A gasket test and a heat aging test were performed in the same manner as in Examples 1 to 3 on a commercially available polyurethane sheet having a thickness of 2 mm. The results are shown in Table 1. In addition, the used polyurethane is as follows.
・ Polyurethane: trade name “Milactolan E394PDTA” manufactured by Nippon Miractolan Co., Ltd.

[Comparative Example 4]
Based on the method described in Synthesis Example 1 of Patent Document 2, a urethane-based imide-modified silicone elastomer containing urethane as an elastomer component was prepared. About this urethane type imide modified silicone elastomer, the gasket test and the heat aging test were done like Example 1-3. The results are shown in Table 1.

  As is apparent from Table 1, Examples 1 to 3 show that the gasket test shows better results than Comparative Examples 1 to 4. Moreover, Examples 1-3 showed the result with little change of breaking strength (TB) before and behind a heat aging test. From these results, it can be said that Examples 1-3 are excellent in heat resistance. In particular, among Examples 1 to 3, Examples 2 and 3 in which a non-siloxane diamine compound was further added together with a diamine compound having a siloxane bond showed excellent results in both the gasket test and the heat aging test. . On the other hand, Comparative Example 1 that is silicone rubber and Comparative Example 2 that is fluororubber have results that are inferior to gasket test results such as thickness retention and appearance, although there is little change in breaking strength (TB) before and after the thermal aging test. Indicated. Moreover, the comparative examples 3 and 4 which have a urethane component showed the result remarkably inferior in both a gasket test and a heat aging test.

Claims (7)

Formula (I):

[Wherein, R ₁ represents a divalent organic group containing an aromatic ring or an aliphatic ring. R ₂ and R ₃ are the same or different groups and represent a divalent organic group. R _{4 to} R ₇ are the same or different groups, and each represents hydrogen, an alkyl group, or a phenyl group. R ₈ represents a tetravalent organic group containing 4 or more carbons. n represents an integer of 1 to 160. m shows the integer of 1-100. ] The imide modified silicone elastomer characterized by the above-mentioned. A polysiloxane-urea compound obtained by chain-extending diisocyanate with a diamine compound having a siloxane bond by a urea bond;
Tetracarboxylic dianhydride;
2. The imide-modified silicone elastomer according to claim 1, which is a copolymer imidized after crosslinking polyamic acid obtained by mixing and reacting.   The imide-modified silicone elastomer according to claim 2, wherein a diamine compound having no siloxane bond is further added together with the diamine compound having a siloxane bond.   The imide-modified silicone elastomer according to any one of claims 1 to 3, which has an imide fraction of 5 to 80% by weight.   The imide-modified silicone elastomer according to any one of claims 1 to 4, having an imide fraction of 10 to 30% by weight.   A molded article comprising the imide-modified silicone elastomer according to any one of claims 1 to 5.   The molded article according to claim 6, which is a gasket.