JP2009084499A - Curable composition and crosslinked rubber therefrom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curable composition which can be suitably used for forming a crosslinked rubber having low hardness and excellent vibration damping properties and has excellent moldability and a crosslinked rubber obtained therefrom. <P>SOLUTION: The curable composition comprises (A) an isobutylene-based polymer containing at least more than one of alkenyl groups to be subjected to hydrosilylation reaction, in its molecule, (B) a curing agent containing at least two hydrosilyl groups in the molecule, (C) a hydrosilylation catalyst, (D) a plasticizer and (E) an inorganic filler as essential components, and has flowability at a normal temperature. The crosslinked rubber is obtained from the curable composition and has rubber hardness after curing of ≤15° in a type A durometer defined by JIS K 6253 and a dissipation factor (tanδ) value of ≥0.4 measured by a dynamic viscoelasticity apparatus under conditions at ≤23°C and 100 Hz. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a curable composition excellent in moldability for forming a crosslinked rubber having low hardness and excellent vibration damping properties, and the crosslinked rubber. More specifically, it contains an isobutylene polymer having more than one alkenyl group in one molecule, a compound having at least two hydrosilyl groups in one molecule, a hydrosilylation catalyst, a plasticizer, and an inorganic filler as essential components. The present invention relates to a polyisobutylene-based curable composition excellent in moldability, which can efficiently form a crosslinked rubber having a low hardness and excellent vibration damping properties by a curing reaction, and the crosslinked rubber. Since the polyisobutylene-based crosslinked rubber obtained from the curable composition of the present invention has low hardness and high vibration damping properties, it absorbs vibration in various fields such as electric / electronics, automobiles, energy, and medical. Can be used in a wide range of applications that require high performance and shock absorption.

  Conventionally, (A) a saturated hydrocarbon polymer containing at least one alkenyl group or alkynyl group capable of hydrosilylation reaction in one molecule, and (B) curing containing at least two hydrosilyl groups in the molecule. It is known that a curable composition comprising an agent and (C) a hydrosilylation catalyst is useful as a sound and vibration isolating material. In Patent Document 1, an isobutylene polymer is exemplified as one of the saturated hydrocarbon polymers, and a cross-linked rubber having a hardness of 38 ° to 40 ° and a dynamic viscoelasticity at 23 ° C. of 0.4. It has been described to have a high loss tangent of ~ 0.5.

Moreover, although the patent documents 2-4 shown below are mentioned as another related literature, The relationship is mentioned later.
Japanese Patent No. 3503844 JP2007-131665A Japanese Patent Laying-Open No. 2005-255883 JP-A-2005-320524

  However, the cured composition, that is, the isobutylene polymer having an alkenyl group as one of the saturated hydrocarbon polymers as the component (A), (B) a modified hydrogen polysiloxane, (C) a platinum complex catalyst, A rubber exemplified as a crosslinked rubber obtained from a curable composition comprising fine silica powder, a plasticizer, and other additives has a loss tangent (tan δ) at 23 ° C. in a dynamic viscoelasticity measurement of 0.4 to 0. Although the hardness is as high as 0.5, the hardness is 38 ° to 40 °, and there is no description of a crosslinked rubber having a low hardness.

  On the other hand, in recent years, there has been an increasing demand for suppressing sound and vibration, and the contents of the request have been expanded. In particular, precision electronic components incorporating a rotating body such as an optical / magnetic disk, that is, personal computers, portable audios, mobile phones, and the like have been ported, and demands for durability and reliability are increasing. There are also increasing opportunities for mounting on vibrating vehicles such as automobiles. These electronic devices need to be devised to suppress vibrations themselves and to be protected from external impacts and vibrations.

  Rubber is usually used for many countermeasures such as vibration suppression, vibration insulation, and shock absorption. However, conventional rubbers generally have a high rubber hardness of 20 ° or more in a type A durometer, and such rubbers are considered to be ineffective for vibration isolation and resonance suppression in a low frequency range. In order to increase the vibration insulation and resonance suppression effect in the low frequency range, it is generally known that the rubber hardness is reduced. However, the low hardness rubber is difficult to handle and has a large compression set. Have practical problems. In Patent Document 2, there is also known a crosslinked rubber having low hardness corresponding to Asker C hardness 26 or 10, that is, about 10 °, 5 ° or less in a type A durometer, but there is no description regarding vibration absorption, and rubber However, only liquid isoprene rubber and liquid butadiene rubber are described, and high vibration absorption cannot be expected.

  In Patent Document 3, a block copolymer comprising a block composed of a styrene monomer in a molecule and a vinyl-polyisoprene block and having a main dispersion peak of tan δ at −40 ° C. or higher is a rubber composition having a weight of 100%. A composition for a vibration absorber having a tan δ value at 100 Hz of 25 ° C. of 0.3 or more and a hardness of A5 to 80 ° as a rubber elastic body mixed with 10 to 70 parts by weight and crosslinked. Is described.

  In order to solve the problem that the block copolymer alone has a problem that the vibration damping performance is suddenly lost at a temperature lower than the peak temperature of tan δ, while the EPDM that is an elastic rubber alone has a problem that the vibration damping performance is insufficient. By trying to blend, we tried to solve the previous issue.

  When reading from FIG. 2 described in Patent Document 3, a rubber elastic body having a hardness of 10 A and a tan δ value at 25 ° C. of 0.4 or more is exemplified as a particularly low hardness rubber elastic body. The property of the composition is not mentioned, but if it is presumed from blending a styrenic block polymer and a rubber, it is only handled as a normal solid rubber or thermoplastic elastomer. Further, when the value of tan δ at 50 ° C. of the crosslinked rubber having a hardness of 10A is read from FIG. 2 described in Patent Document 3, it is 0.3 or less, and a loss of vibration damping performance in a high temperature region can be seen.

  On the other hand, Patent Document 4 proposes a thermoplastic elastomer containing butyl rubber, a liquid rubber at 23 ° C., and a crystalline olefin resin, and the measurement temperature is not shown at a Shore hardness A of 20 ° or less. A composition having a tangent of 1.0 or more and excellent vibration absorption is shown. However, although this composition is a thermoplastic elastomer to the last, it is estimated that it is inferior to compression set like a normal thermoplastic elastomer, although it is not described. Also, the molding is limited to extrusion and injection molding using pellets.

  As a result of various studies, the present inventor has found that (A) an isobutylene polymer containing at least one hydrosilylation-capable alkenyl group in the molecule, and (B) at least two hydrosilyl groups in the molecule. Containing a curing agent containing (C) a hydrosilylation catalyst, (D) a plasticizer, and (E) an inorganic filler as essential components, and having a fluidity at room temperature, the rubber hardness after curing is JIS A crosslinked rubber having a loss tangent (tan δ) value of 0.4 or more measured at 100 Hz under a condition of 15 ° or less in a type A durometer specified by K 6253 and 23 ° C. using a dynamic viscoelastic device. The present invention was completed.

That is, the present invention
(I). The following components (A) to (D) are essential components, and the rubber hardness after curing is 15 ° or less in a type A durometer defined in JIS K 6253, and 100 Hz under a dynamic viscoelastic device at 23 ° C. A curable composition having fluidity at room temperature, characterized in that the value of loss tangent (tan δ) measured below is 0.4 or more,
(A) Isobutylene polymer containing at least one alkenyl group capable of hydrosilylation reaction in the molecule, (B) Curing agent containing at least two hydrosilyl groups in the molecule, (C) Hydrosilylation catalyst , (D) plasticizer, (E) inorganic filler,
(II). The curable composition comprising the components (A) to (E) as essential components has a viscosity measured at 23 ° C. and a B-type rotational viscometer at 10 rpm of 5000 Pa · s or less as described in (I). Composition,
(III). The rubber after curing has a compression set of 25%, a test temperature of 70 ° C., and a compression set of 10 hours or less as defined in JIS K 6262, which is 10% or less (I), (II) The curable composition according to any one of
(IV). (F) As a component, the curable composition of any one of (I)-(III) containing tackifying resin,
(V). The curable composition according to any one of (I) to (IV), wherein the number average molecular weight of the isobutylene polymer containing an alkenyl group as the component (A) is 3,000 to 50,000,
(VI) The curable composition according to any one of (I) to (V), wherein the component (B) is a compound having a hydrosilyl group represented by the general formula (1). ,
General formula (1):

(VII). Component (F) is a terpene resin, hydrogenated terpene resin, aliphatic (C5) petroleum resin, aromatic (C9) petroleum resin, aliphatic (C5) / aromatic (C9) petroleum resin, alicyclic The curable composition according to any one of (I) to (VI), which is at least one selected from group petroleum resins,
(VIII). The curable composition according to any one of (I) to (VII), wherein the rubber hardness after curing is 10 ° or less in a type A durometer defined by JIS K 6253,
(IX). The value of loss tangent (tan δ) measured under a condition of 100 Hz by a dynamic viscoelastic device is 0.3 or more in a temperature range of 0 ° C. to 50 ° C. (I) to (I) VIII) the curable composition according to any one of the above,
(X). A crosslinked rubber obtained by heat-molding the curable composition according to any one of (I) to (IX),
(XI). The present invention relates to a crosslinked rubber obtained by molding the curable composition according to any one of (I) to (X) with a liquid injection molding machine.

Since the polyisobutylene-based crosslinked rubber obtained from the curable composition of the present invention has low hardness and high vibration damping properties, it has a high resonance suppression effect and is excellent in vibration damping properties in a low frequency range. In various fields such as electricity / electronics, automobiles, energy, and medicine, it can be used for a wide range of applications that require vibration absorption and shock absorption. Moreover, such a crosslinked rubber can be efficiently obtained by the same handling as an adhesive or potting agent such as coating, injection, screen printing, etc., press molding, injection molding, transfer molding, extrusion molding, etc. it can.
It can be obtained with good productivity.

  The component (A) used in the present invention is an isobutylene polymer having at least one alkenyl group capable of hydrosilylation reaction in the molecule. Here, the isobutylene polymer is not limited to those in which all of the monomer units are formed from isobutylene units, but includes those having monomer units copolymerizable with isobutylene in the isobutylene polymer. Sure. However, the monomer copolymerizable with isobutylene is preferably contained within a range that does not significantly impair vibration damping due to the isobutylene unit, and is preferably 50% by weight or less, more preferably 30% by weight or less, particularly preferably. A range of 20% by weight or less is preferred.

  Examples of such monomer components include olefins having 4 to 12 carbon atoms, vinyl ethers, aromatic vinyl compounds, vinyl silanes, allyl silanes, and the like. Specific examples of such copolymer components include 1-butene, 2-butene, 2-methyl-1-butene, 3-methyl-1-butene, pentene, 4-methyl-1-pentene, hexene, Vinyl cyclohexane, methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, styrene, α-methyl styrene, dimethyl styrene, pt-butoxy styrene, p-hexenyloxy styrene, p-allyloxy styrene, p-hydroxy styrene , Β-pinene, indene, vinyldimethylmethoxysilane, vinyltrimethylsilane, divinyldimethoxysilane, divinyldimethylsilane, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, trivinylmethylsilane, tetravinylsilane Allyldimethylmethoxysilane, Examples include allyltrimethylsilane, diallyldimethoxysilane, diallyldimethylsilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-methacryloyloxypropylmethyldimethoxysilane. Particularly preferably, all of the monomer units are formed from isobutylene units.

  The number average molecular weight (GPC method, in terms of polystyrene) of the isobutylene polymer (A) is preferably about 2,000 to 100,000, more preferably 3, from the viewpoint of easy handling and rubber hardness after curing. 000 to 50,000. Generally, as the number average molecular weight increases, the hardness of the resulting crosslinked rubber tends to decrease.

  The alkenyl group is not particularly limited as long as it is a group containing a carbon-carbon double bond that is active for hydrosilylation reaction. Examples of the alkenyl group include aliphatic unsaturated hydrocarbon groups such as vinyl group, allyl group, methylvinyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, cyclopropenyl group, cyclobutenyl group, cyclopentenyl group, cyclopentyl group, and the like. Examples thereof include cyclic unsaturated hydrocarbon groups such as hexenyl groups, methacryl groups and the like. Among these, an allyl group is preferable from the viewpoint of high activity for hydrosilylation reaction and relatively easy introduction of an alkenyl group.

  In the component (A) in the present invention, the alkenyl group capable of hydrosilylation reaction may be present at the main chain end or side chain of the isobutylene polymer, or may be present in both. In particular, when the alkenyl group is at the end of the main chain, the effective network chain amount of the isobutylene polymer component contained in the finally formed cured product is increased, so that it has low strength but high strength and low compression set. This is preferable from the viewpoint of easily obtaining a rubber-like cured product.

  As the method for producing the component (A) of the present invention, a compound having an unsaturated group in a polymer having a functional group such as a hydroxyl group as disclosed in JP-A-3-152164 and JP-A-7-304969 is disclosed. To introduce an unsaturated group into the polymer. In addition, to introduce an unsaturated group into a polymer having a halogen atom, a method of performing a Friedel-Crafts reaction with an alkenylphenyl ether, a method of performing a substitution reaction with allyltrimethylsilane in the presence of a Lewis acid, various phenols and Friedel For example, a method in which the above alkenyl group introduction method is used in combination with the introduction of a hydroxyl group by carrying out a kraft reaction. Furthermore, a method of introducing an unsaturated group at the time of polymerization of a monomer as disclosed in US Pat. No. 4,316,973, Japanese Patent Laid-Open No. 63-105005, and Japanese Patent Laid-Open No. 4-288309 is also possible.

  The alkenyl group should be present in an amount exceeding an average of 1 in one molecule of the polymer (A), preferably 5 or less. When the number of alkenyl groups contained in one molecule of the polymer (A) is 1 or less on average, the curability is insufficient and the resulting network structure is incomplete, and a good molded product is obtained. Absent. Further, when the number of alkenyl groups contained in one molecule increases, the network structure becomes too dense, so that the resulting molded product is hard and brittle, which is not preferable. In particular, when the number is 5 or more, the tendency becomes remarkable.

  The compound having a hydrosilyl group exceeding 1 on average in one molecule as the component (B) in the present invention can be used without particular limitation as long as it has a hydrosilyl group, but has a number average molecular weight of 400 to 3,000. The thing of 500-1,000 is more preferable. When the number average molecular weight is less than 400, it is volatilized at the time of heat curing and a sufficient cured product cannot be obtained, and when it exceeds 3,000, a sufficient curing rate cannot be obtained. Examples of such compounds include organohydrogenpolysiloxanes modified with organic groups from the standpoint of availability of raw materials and compatibility with the component (A). These (B) components are preferably those having good compatibility with the (A) component. In particular, when the viscosity of the whole system is low, use of a material having low compatibility may cause phase separation and cause poor curing. Specifically showing the structure of such an organohydrogenpolysiloxane, for example,

(In the formula, 1 <b + c ≦ 40, 1 <b ≦ 20, 0 <c ≦ 38. R is a hydrocarbon group having 2 to 20 carbon atoms in the main chain and containing one or more phenyl groups. You may)

(In the formula, 0 ≦ d + e ≦ 40, 0 ≦ d ≦ 20, 0 <e ≦ 38. R is a hydrocarbon group having 2 to 20 carbon atoms in the main chain and containing one or more phenyl groups. Or)

(In the formula, 3 ≦ f + g ≦ 20, 1 <f ≦ 20, 0 <g ≦ 18. R is a hydrocarbon group having 2 to 20 carbon atoms in the main chain and containing one or more phenyl groups. Or a chain-like or cyclic group represented by
Specific examples of the (B) component having relatively good compatibility with the (A) component and the (C) component, or relatively good dispersion stability and curing speed include the following.

In the formula, 1 <k + l ≦ 20, 1 <k ≦ 19, 0 <l ≦ 18, and R is a hydrocarbon group having 8 or more carbon atoms.

  As a more specific example of the component (B), methyl hydrogen polysiloxane is used in order to ensure compatibility with the component (A) and to adjust the amount of SiH, α-olefin, styrene, α-methylstyrene, Examples include compounds modified with allyl alkyl ethers, allyl alkyl esters, allyl phenyl ethers, allyl phenyl esters, and the like, and examples include the following structures.

However, 1 <p + q ≦ 20, 1 <p ≦ 19, and 0 <q ≦ 18.

  The amount of the hydrosilyl group-containing compound as the component (B) in the present invention is such that [total amount of hydrosilyl groups in the component (B)] / [total amount of alkenyl groups in the component (A)] is 0.5 or more. Preferably, it is 0.7 or more. When [total amount of hydrosilyl groups in component (B)] / [total amount of alkenyl groups in component (A)] is less than 0.5, the resulting crosslinked rubber has a low crosslink density, so the compression set is large. The adhesiveness is high and handling of the molded body becomes difficult. In addition, if [total amount of hydrosilyl groups in component (B)] becomes excessive compared to [total amount of alkenyl groups in component (A)], formation of a three-dimensional network skeleton becomes difficult, and similarly obtained It becomes difficult to handle the molded product. Thus, it is necessary to pay attention to both the lower limit and the upper limit for the amount of component (B) used.

It does not specifically limit as a hydrosilylation catalyst which is (C) component of this invention, Arbitrary things can be used. For example, solid platinum supported on a carrier such as chloroplatinic acid, platinum alone, alumina, silica, carbon black; platinum-vinylsiloxane complex {for example, Pt _X (ViMe ₂ SiOSiMe ₂ Vi) _y , Pt [(MeViSiO) ₄ ] _z }; platinum-phosphine complex {eg, Pt (PPh ₃ ) ₄ , Pt (PBu ₃ ) ₄ }; platinum-phosphite complex {eg, Pt [P (OPh) ₃ ] ₄ , Pt [P (OBu) ₃ ] ₄ (wherein Me represents a methyl group, Bu represents a butyl group, Vi represents a vinyl group, Ph represents a phenyl group, x, y, and z represent integers), Pt ( _{acac) 2} (However, acac represents acetylacetonato), also platinum described in U.S. Pat. No. 3,159,601 and 3,159,662 of Ashby et al - hydrocarbon complex And platinum alcoholate catalysts described in Lamoreaux et al U.S. Pat. No. 3,220,972 may also be mentioned.
Examples of catalysts other than platinum compounds include RhCl (PPh ₃ ) ₃ , RhCl ₃ , Rh / Al ₂ O ₃ , RuCl ₃ , IrCl ₃ , FeCl ₃ , AlCl ₃ , PdCl ₂ .2H ₂ O, NiCl _2. , TiCl _{4 and the} like.

These catalysts may be used alone or in combination of two or more. From the viewpoint of catalytic activity, chloroplatinic acid, platinum-olefin complexes, platinum-vinylsiloxane complexes, Pt (acac) _{2 and the} like are preferable. Although there is no restriction | limiting in particular as catalyst usage-amount, It is good to use in the range of 10 ^<-8 > ^-10 < ^-1 > mol with respect to ¹ mol of alkenyl groups in (A) component. Preferably it is used in the range of 10 ⁻⁶ to 10 ⁻² mol. If it is less than 10 ⁻⁸ mol, the curing rate is slow and the curability is likely to be unstable. On the other hand, if it exceeds 10 ⁻¹ mol, it is difficult to ensure the pot life, which is not preferable.

  As the plasticizer which is the component (D) of the present invention, a general plasticizer used for improving rubber fluidity, kneadability, moldability and the like can be used. Those having good compatibility are preferred. Specific examples of such a plasticizer include, for example, polybutene, hydrogenated polybutene, α-methylstyrene oligomer, liquid polybutadiene, hydrogenated liquid polybutadiene, paraffin oil, naphthene oil, polyα-olefin, sebacic acid ester and adipic acid ester. And fatty acid esters. Moreover, even if the plasticizer has poor compatibility with the isobutylene polymer alone, it can be used in combination with a plasticizer with good compatibility.

  The amount of component (D) used is 10 to 300 parts by weight, preferably 30 to 250 parts by weight, more preferably 50 to 200 parts by weight, based on 100 parts by weight of component (A). If the amount of these components used is too small, it will be difficult to reduce the hardness of the resulting crosslinked rubber, and the fluidity of the curable composition will be low, making handling difficult. On the other hand, when the amount of these used is too large, the strength of the resulting rubber is insufficient and the compression set becomes large.

  As the inorganic filler as the component (E) of the present invention, silica, carbon black, calcium carbonate, magnesium carbonate, aluminum hydroxide, clay, talc, zinc white, diatomaceous earth, sulfuric acid, which are used for usual rubber reinforcement, are used. Common inorganic fillers such as barium can be mentioned. Among these, from the balance between the fluidity of the curable composition and the mechanical properties of the resulting crosslinked rubber, fine powder silica, especially fine powder silica with a hydrophobic surface, carbon black, colloidal calcium carbonate, aluminum hydroxide, calcined clay, etc. Is preferred.

  On the other hand, since the curable composition of the present invention utilizes a hydrosilylation reaction as a curing reaction, it is necessary to pay attention to the presence or absence of inhibition of the hydrosilylation reaction and the moisture in the reaction system when using the component (E). There is. From the standpoint of inhibiting the hydrosilylation reaction, if there is a lot of water, hydrogen gas is generated by the reaction between the hydrosilyl group of the curing agent (B) and water during the curing reaction, and voids are generated in the resulting cured product. It will be. Therefore, it is necessary to remove moisture as necessary.

  The amount of component (E) used is 2 to 300 parts by weight, preferably 5 to 200 parts by weight, per 100 parts by weight of component (A). However, the amount of these (E) components used varies greatly depending on the type of the (E) component used. For example, fine powdered silica with a large reinforcing effect and thickening effect can be expected to exhibit the desired physical properties by using a small amount, but colloidal calcium carbonate used as a bulking agent aims to achieve similar physical properties. Needs to be used in large quantities.

  The tackifier resin which is the component (F) of the present invention is used for the purpose of enhancing the vibration damping property of the crosslinked rubber obtained from the curable composition of the present invention.

  As the tackifier resin as the component (F), a general tackifier resin used as an adhesive can be used. Specific examples include natural products such as rosin resin, terpene resin, terpene phenol resin and derivatives thereof, aliphatic (C5) petroleum resin, aromatic (C9) petroleum resin, aliphatic (C5) / aromatic (C9). ) Based petroleum resin, alicyclic petroleum resin, coumarone indene resin, styrene resin, xylene resin and the like.

  Among these, those having good compatibility with the isobutylene polymer as the component (A) or good compatibility with the mixture of the component (A) and the plasticizer as the component (D) are preferable. Moreover, since the curable composition of this invention utilizes hydrosilylation reaction as hardening reaction, the thing with little inhibition to hydrosilylation reaction is preferable. From these viewpoints, terpene resins, hydrogenated terpene resins, aliphatic (C5) petroleum resins, aliphatic (C5) / aromatic (C9) petroleum resins, and alicyclic petroleum resins are particularly preferable.

  Further, these components (F) are used for the purpose of vibration damping properties of the crosslinked rubber obtained from the curable composition of the present invention, particularly resonance suppression in the resonance region. When the component (F) is used, the component (F) may be selected based on the glass transition temperature so that the resonance suppression effect is exhibited in the temperature range where the crosslinked rubber is used. However, if the glass transition temperature of the tackifying resin as the component (F) is too high, the vibration damping effect in the use temperature range is not sufficiently exhibited. On the other hand, if the glass transition temperature is too low, the cross-linked rubber is too sticky and difficult to handle. In consideration of the balance between the two, it is preferable to select the component (F) having the optimum glass transition temperature.

  The amount of component (F) used is 5 to 300 parts by weight, preferably 10 to 200 parts by weight, per 100 parts by weight of component (A). If the amount of these components used is too small, the vibration-damping effect of the resulting crosslinked rubber will be insufficient. If the amount used is too large, the resulting crosslinked rubber will become more sticky and difficult to handle, and it will be permanently compressed. Strain also increases.

  In addition, the curable composition comprising the components (A) to (E) and the components (A) to (F) of the present invention has a storage stability improver for the purpose of improving the storage stability of the curable composition. Antioxidants and UV absorbers for the purpose of improving heat resistance and weather resistance, various pigments for the purpose of coloring, metal soaps, waxes, silicon compounds for the purpose of improving surface properties, etc. Agents and solvents can be used.

  The storage stability improver is not particularly limited as long as it is an ordinary stabilizer known as a storage stabilizer of the component (B) of the present invention and can achieve the intended purpose. is not. Specifically, a compound containing an aliphatic unsaturated bond, an organic phosphorus compound, an organic sulfur compound, a nitrogen-containing compound, a tin compound, an organic peroxide, or the like can be preferably used. Specifically, 2-benzothiazolyl sulfide, benzothiazole, thiazole, dimethylacetylene dicarboxylate, diethylacetylene dicarboxylate, 2,6-di-t-butyl-4-methylphenol, butylhydroxyanisole, vitamin E, 2- (4-morphodinyldithio) benzothiazole, 3-methyl-1-buten-3-ol, acetylenically unsaturated group-containing organosiloxane, acetylene alcohol, 3-methyl-1-butyl-3-ol , Diallyl fumarate, diallyl maleate, diethyl fumarate, diethyl maleate, dimethyl maleate, 2-pentenenitrile, 2,3-dichloropropene, and the like, but are not limited thereto.

  Moreover, there is no restriction | limiting in particular as a method of obtaining the curable composition of this invention, (A)-(E) component or (A)-(F) component, Furthermore, the various additives used as needed And a method of mixing the filler using a rotary mixer such as a planetary mixer or a biaxial disperser, a kneader, a bumper mixer, or a roll. Here, it is desirable to uniformly disperse and stabilize the inorganic filler which is the component (E) in the curable composition of the present invention, and to remove moisture contained in the curable composition as much as possible. If the dispersion of the filler in the component (A) is not uniform or unstable, the properties of the composition change greatly with time. Moreover, when there is much water | moisture content in a composition, it will foam by reaction of (B) component and a water | moisture content at the time of hardening reaction, and a void will be produced in crosslinked rubber.

  The curable composition of the present invention thus obtained has fluidity at room temperature, and has a viscosity measured at 23 ° C. with a B-type rotational viscometer of 5,000 Pa · s or less. . Such a composition having fluidity at room temperature is applicable to liquid injection molding and can efficiently form a crosslinked rubber. This liquid injection molding was developed for heat-curing liquid silicone rubber, and is known as a method for molding liquid rubber that is simple and excellent in productivity.

  In addition, the method for obtaining the crosslinked rubber from the curable composition of the present invention is not limited to the liquid injection molding, and the same method as that of a thermosetting liquid rubber that is generally used can be employed. It is possible to apply a method for obtaining a rubber molded body, such as coating, injection, screen printing, etc., and the same handling as an adhesive or potting agent, press molding, injection molding, transfer molding, extrusion molding or the like.

  Moreover, in these various handling methods, the curable composition of the present invention can be handled as a one-component form containing all components, or all components can be mixed so that the components (B) and (C) are not mixed. It can also be handled as a two-liquid form distributed to the liquid. In the former case, since the reaction can proceed gradually even at room temperature, storage at a low temperature is required, but the trouble of mixing two liquids at the time of molding can be omitted. In the latter case, it is necessary to mix the two liquids at the time of molding and apply, fill, and inject in a state that does not contain bubbles, but it is advantageous for long-term storage of the curable composition. is there. Such a two-component liquid curable composition can be handled by using a two-component mixing and discharging device used in a liquid injection molding system developed for liquid silicone, a two-component urethane resin, or an epoxy resin. The two-component mixing / discharging device used can be used.

  The polyisobutylene-based crosslinked rubber obtained from the curable composition of the present invention has a rubber hardness of 15 ° or less, particularly preferably 10 ° or less, in a type A durometer as defined in JIS K 6253. Such a low hardness rubber generally has a low resonance frequency and is excellent in vibration insulation. However, on the other hand, the rubber before cross-linking has disadvantages such as low productivity and large compression set because of its high tackiness. In this respect, the curable composition of the present invention can be applied to a molding system for liquid rubber as described above, and can ensure high productivity. Moreover, since the hydrosilylation reaction is used as a crosslinking reaction, the compression set is small and the performance with excellent reliability is exhibited.

  In addition, the polyisobutylene-based crosslinked rubber obtained from the curable composition of the present invention has a loss tangent (tan δ) value of 0.4 at 23 ° C. measured in a shear mode with a frequency of 100 Hz using a dynamic viscoelastic device. That's it. More preferably, it is 0.4 or more at 23 ° C., and the loss tangent (tan δ) in the temperature range of 0 ° C. to 50 ° C. is 0.3 or more. This loss tangent (tan δ) is the ratio of the storage elastic modulus and loss elastic modulus measured by a dynamic viscoelastic device, and the higher this value, the higher the vibration damping property.

  The polyisobutylene-based crosslinked rubber obtained from the curable composition of the present invention has a compression set of 25%, a test temperature of 70 ° C. and a compression set of 10% or less at a test time of 22 hours as defined in JIS K 6262. is there. In general, rubber parts that require vibration absorption and shock absorption are often used in a compressed state. For materials with large compression set, the properties of rubber change over time. And shock absorption will change greatly. That is, in order to ensure highly reliable vibration absorption and shock absorption over a long period of time, it is required that the compression set is small.

  Such a polyisobutylene-based crosslinked rubber obtained from the curable composition of the present invention utilizes a high damping property, and in various fields such as electric / electronics, automobiles, energy, and medical, vibration absorption, shock absorption, etc. Can be used for a wide range of applications.

  Next, although the curable composition of this invention and its crosslinked rubber are demonstrated concretely by an Example, this invention is not limited only to these Examples.

(Production Example 1)
In the presence of a platinum catalyst, 0.5 equivalent of an α-olefin of the total amount of hydrosilyl groups is added to methyl hydrogen silicone having an average of (-Si-O-) repeating units of 7.5, and an average of about 1 per molecule. The compound (B-1) which has 5.5 hydrosilyl groups was obtained. The Si—H group content of this compound was 6 mmol / g.

Example 1
According to the method described in JP-A-8-127683, Production Example 1, an allyl group-terminated polyisobutylene (A-1) having a molecular weight of about 16,000 and an allyl group number of 2.0 was obtained as component (A). . To 100 g of this component (A), 120 g of DURASYN 170 (manufactured by Ineos Singapore) as component (D), 2.0 g of MARK A-50 (manufactured by Adeka) as an antioxidant, and Tinuvin-765 (Ciba) -Japan Co., Ltd.) 1.0 g, (E) component carbon black ASTM No. 140 g of N-762 was added and kneaded with a mixer. This mixture was dehydrated by heating under reduced pressure. After cooling, 0.7 g of acetylene alcohol (Nisshin Chemical Industry Co., Ltd., Surfynol 61) as a preservative improver for this mixture, platinum vinylsiloxane complex catalyst (D) made by DM Square Japan Co., Ltd., PT-VTSC-3.0X) (0.3 g) and (B) component modified methylhydrogenpolysiloxane (B-1) (6 g) were sequentially mixed to obtain a liquid curable composition. These recipes are shown in Table 1.

  The viscosity of the liquid curable composition thus obtained was measured at 23 ° C. with a TVB-10 type viscometer manufactured by Toki Sangyo Co., Ltd. and found to be 600 Pa · s at 10 rpm.

  Next, this liquid composition was subjected to hot press molding at 180 ° C. for 3 minutes using a spacer having a thickness of 2 mm and two press plates to obtain a cured product sheet having a thickness of 2 mm. Further, the obtained cured sheet was subjected to heat treatment at 180 ° C. for 4 hours with a hot air dryer, and then the following various characteristics were measured. These results are shown in Table 2.

  Hardness: Measured with a type A durometer as defined in JIS K 6253.

  Loss tangent by dynamic viscoelasticity measurement (tan δ): Loss tangent at 0 ° C, 23 ° C, and 50 ° C in shear mode with a frequency of 100 Hz using dynamic measurement device DVA-200 manufactured by IT Measurement Control Co., Ltd. (Tan δ) was measured.

  Compression set: The compression set as defined in JIS K 6262 was measured at a compression rate of 25%, a test temperature of 70 ° C., and a test time of 22 hours.

(Examples 2-3, Comparative Example 1)
According to the same method as in Example 1, a curable composition was obtained according to the formulation table in Table 1. Moreover, it carried out similarly to the said Example 1, the hardened | cured material sheet was obtained, and hardness, loss tangent, and compression set were measured. These results are shown in Table 2.

Example 4
Next, 100 g of the same component (A) used in Example 1, 75 g of DURASYN 170 (produced by Ineos Singapore) as component (D), and glass transition temperature of about 60 ° C. as component (F) 50 g of hydrogenated terpene resin, 2.0 g of MARK A-50 (manufactured by Adeka Co., Ltd.) as an antioxidant, 1.0 g of tinuvin-765 (manufactured by Ciba Japan Co., Ltd.), carbon which is component (E) Black ASTM No. 120 g of N-762 was added and kneaded with a mixer. This mixture was dehydrated by heating under reduced pressure. After cooling, 0.6 g of acetylene alcohol (manufactured by Nissin Chemical Industry Co., Ltd., Surfynol 61) as a preservative improver for this mixture, platinum vinylsiloxane complex catalyst (DM Square Japan Co., Ltd.) as component (C), 0.2 g of PT-VTSC-3.0X) and 6 g of the modified methyl hydrogen polysiloxane (B-1) as component (B) were sequentially mixed to obtain a liquid curable composition. These recipes are shown in Table 1.

  Moreover, it carried out similarly to the said Example 1, the hardened | cured material sheet was obtained, and hardness, loss tangent, and compression set were measured. These results are shown in Table 2.

(Example 5, Comparative Example 2)
In the same manner as in Example 4, a curable composition was obtained according to the formulation table in Table 1. Moreover, it carried out similarly to the said Example 1, the hardened | cured material sheet was obtained, and hardness, loss tangent, and compression set were measured. These results are shown in Table 2.

  Next, cylindrical crosslinked rubber having a diameter of 29 mm and a thickness of 12.5 mm was obtained in accordance with Examples 1 to 3 and Comparative Examples 1 and 2. A vibration transmission test using a vibration test apparatus i210LG / SA03 manufactured by IMV Corporation was performed on these cylindrical crosslinked rubbers. The test conditions are as follows.

Load: about 7kg per piece
Acceleration: 0.2G
Frequency: 5-100Hz
The results are shown in FIG.

  As is clear from FIG. 1, the low-hardness polyisobutylene-based crosslinked rubbers of Examples 1 to 5 have a lower resonance frequency than the polyisobutylene-based crosslinked rubber having a hardness A of 28 ° and the same as 23 °. Accordingly, the vibration transmissibility in the frequency region of 40 Hz or higher is low. That is, the vibration isolation effect is large.

  The isobutylene-based polymer containing at least one alkenyl group capable of hydrosilylation reaction in the molecule (A) of the present invention shown in these Examples, and (B) containing at least two hydrosilyl groups in the molecule The curable composition containing (C) a hydrosilylation catalyst, (D) a plasticizer, and (E) an inorganic filler as essential components has fluidity at room temperature, and conforms to JIS K 6253. Poly which has a hardness of 15 ° or less in a specified type A durometer and a loss tangent (tan δ) value of 0.4 or more measured at 23 ° C. and 100 Hz using a dynamic viscoelastic device. An isobutylene-based crosslinked rubber is provided. Further, the obtained low-hardness polyisobutylene-based crosslinked rubber has high vibration damping properties. The resonance suppression effect in the low frequency range is high, and since it has particularly low hardness, it has high vibration insulation.

It is a figure which shows the frequency characteristic of the vibration transmissibility of the crosslinked rubber obtained by the Example and the comparative example.

Claims (11)

The following components (A) to (D) are essential components, and the rubber hardness after curing is 15 ° or less in a type A durometer defined in JIS K 6253, and 100 Hz under a dynamic viscoelastic device at 23 ° C. A curable composition having fluidity at room temperature, wherein a loss tangent (tan δ) value measured below is 0.4 or more.
(A) Isobutylene polymer containing at least one hydrosilylation-reactive alkenyl group in the molecule (B) Curing agent containing at least two hydrosilyl groups in the molecule (C) Hydrosilylation catalyst (D ) Plasticizer (E) Inorganic filler 2. The curable composition according to claim 1, wherein the curable composition comprising the components (A) to (E) as essential components has a viscosity of 5000 Pa · s or less at 23 ° C. and a B-type rotational viscometer at 10 rpm. Composition.   The cured rubber has a compression set of 25%, a test temperature of 70 ° C, a test time of 22 hours and a compression set of 10% or less as defined in JIS K 6262. 2. The curable composition according to item 1.   (F) The curable composition of any one of Claims 1-3 which contains tackifying resin as a component.   The curable composition according to any one of claims 1 to 4, wherein the number average molecular weight of the isobutylene polymer containing an alkenyl group as the component (A) is 3,000 to 50,000. The curable composition according to any one of claims 1 to 5, wherein the component (B) is a compound having a hydrosilyl group represented by the general formula (1).
General formula (1):

  Component (F) is a terpene resin, hydrogenated terpene resin, aliphatic (C5) petroleum resin, aromatic (C9) petroleum resin, aliphatic (C5) / aromatic (C9) petroleum resin, alicyclic The curable composition according to any one of claims 1 to 6, wherein the curable composition is at least one selected from a group petroleum resin.   The curable composition according to any one of claims 1 to 7, wherein the rubber hardness after curing is 10 ° or less in a type A durometer defined in JIS K 6253.   9. The loss tangent (tan δ) value measured under a condition of 100 Hz by a dynamic viscoelastic device is 0.3 or more in a temperature range of 0 ° C. to 50 ° C. 9. 2. The curable composition according to item 1.   Crosslinked rubber obtained by heat-molding the curable composition according to any one of claims 1 to 9.   Crosslinked rubber obtained by shape | molding the curable composition of any one of Claims 1-10 with a liquid injection molding machine.

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