JP2011052232A - Diorganopolysiloxane composition containing discoloration preventing or reducing agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition which prevents or reduces discoloration during long-term storage of diorganopolysiloxane composition by simple and cost-effective means, regardless of the cause. <P>SOLUTION: To the diorganopolysiloxane composition, a trace amount of a (2-pyridylthio-1-oxide) nonferrous metal salt is added in the presence of an iron compound. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to prevention or reduction of discoloration of a diorganopolysiloxane composition, and in particular to prevention or reduction of discoloration of a diorganopolysiloxane composition containing an iron compound.

  It is well known that diorganopolysiloxane compositions can change color during prolonged storage. For example, a diorganopolysiloxane composition containing a diorganopolysiloxane having an alkoxysilyl group at both ends of the molecular chain and an alkoxysilane, which can be cured at room temperature by releasing alcohol in the presence of an organic titanium compound (dealcoholization). Curing type room temperature curable silicone rubber composition) has no unpleasant odor and does not corrode metals. Therefore, it is used as a sealing material for electrical and electronic equipment and building materials, and as an adhesive. It is known to yellow, and the degree of this yellowing increases with time.

  Although the yellowing mechanism of the diorganopolysiloxane composition has many unclear points, an organic titanium compound contained as a curing catalyst is considered to be one of the causes. In addition to organic titanium compounds, it is considered that additives such as amino group-containing silane coupling agents can cause discoloration.

  If the color of the diorganopolysiloxane composition changes during storage, the appearance of the product obtained using the composition also changes, so a diorganopolysiloxane composition that does not change color during storage or has little color change is required. ing. In particular, in the case of a white or light-colored diorganopolysiloxane composition frequently used for various sealing materials, a color change is conspicuous, and thus high discoloration resistance is required.

  JP-A-58-71951 discloses the discoloration of a diorganopolysiloxane composition by combining certain types of thioalkanoic acid esters, di-tert-butylphenol-containing compounds and / or organic phosphites with chelating organotitanium compounds. It is described that it is used to prevent or reduce the above.

  Japanese Patent Application Laid-Open No. 9-3330 discloses that discoloration of a diorganopolysiloxane composition is avoided by using an organic titanium compound having a specific structure.

  However, the techniques described in these publications are only for discoloration caused by the organic titanium compound, and are disadvantageous in terms of cost.

JP 58-71951 A Japanese Patent Laid-Open No. 9-3330

  The object of the present invention is to solve the above-mentioned problems of the prior art. Specifically, the color change during long-term storage of the diorganopolysiloxane composition can be easily performed regardless of the cause. The object is to prevent or reduce by cost-effective means.

  As a result of intensive studies, the present inventor has added a trace amount of (2-pyridylthio-1-oxide) non-ferrous metal salt to the diorganopolysiloxane composition in the presence of an iron compound, so that the color change of the composition can be reduced. The present invention has been completed by finding that it can be prevented or reduced.

  The first aspect of the present invention is an iron compound-containing diorganopoly compound containing 0.0001-0.05% by weight of a bis (2-pyridylthio-1-oxide) nonferrous metal salt based on the total weight of the composition. This is a method for preventing discoloration or reducing discoloration of a siloxane composition.

  The 2nd aspect of this invention is the discoloration prevention or discoloration reducing agent for iron compound containing diorganopolysiloxane compositions which consist of a bis (2-pyridylthio-1-oxide) nonferrous metal salt.

  A third aspect of the present invention is an iron compound-containing diorganopolysiloxane composition comprising 0.0001-0.05% by weight of bis (2-pyridylthio-1-oxide based on the total weight of the composition ) A composition containing a metal salt as a discoloration preventing or discoloration reducing agent.

  As the bis (2-pyridylthio-1-oxide) non-ferrous metal salt in the first, second and third aspects of the present invention, a bis (2-pyridylthio-1-oxide) zinc salt is preferable. Moreover, as an iron compound, iron oxide is preferable.

  The composition of the third aspect of the present invention may contain an inorganic filler such as calcium carbonate. In this case, the inorganic filler may contain the iron compound, preferably iron oxide. The composition may be a condensation reaction curable organopolysiloxane composition. Specifically, (A-1) diorganopolysiloxane 20- having a hydroxyl group or a hydrolyzable group at both ends of the molecular chain. 100% by weight, (A-2) 0-80% by weight of diorganopolysiloxane having a hydroxyl group or hydrolyzable group at one end of the molecular chain, (A-3) having a hydroxyl group or hydrolysable group at both ends of the molecular chain (A) 100 parts by weight of diorganopolysiloxane based on diorganopolysiloxane, 1-300 parts by weight of iron oxide-containing calcium carbonate powder, (C) alkoxysilane or partial hydrolysis thereof 0.5-30 parts by weight of the product and (D) 0.001-10 parts by weight of the curing catalyst. The curing catalyst may be an organic titanium compound.

  According to the present invention, discoloration of a diorganopolysiloxane composition can be prevented or reduced for a long period of time by an easy and relatively inexpensive means.

（式中、Ｍは鉄以外の金属を表す）で表されるものであり、Ｍとしては亜鉛、銅等の非鉄金属が挙げられる。ジオルガノポリシロキサン組成物への配合時における、金属塩固有色による望ましくない着色を回避しうる点で白色のビス（２−ピリジルチオ−１−オキシド）亜鉛塩が好ましい。 The bis (2-pyridylthio-1-oxide) non-ferrous metal salt used in the present invention has the following formula:

(Wherein M represents a metal other than iron), and M includes non-ferrous metals such as zinc and copper. A white bis (2-pyridylthio-1-oxide) zinc salt is preferable in that undesirable coloring due to the inherent color of the metal salt at the time of blending with the diorganopolysiloxane composition can be avoided.

  In the presence of iron ions, bis (2-pyridylthio-1-oxide) non-ferrous metal salts immediately produce bis (2-pyridylthio-1-oxide) iron salts (iron pyrithione) by a metal ion exchange reaction. Since the bis (2-pyridylthio-1-oxide) iron salt exhibits a blue color, the color change of the diorganopolysiloxane composition, particularly yellowing, can be offset, and the color change of the entire composition can be suppressed.

  When the diorganopolysiloxane composition contains an iron compound, iron ions are gradually supplied from the iron compound, so that the amount of bis (2-pyridylthio-1-oxide) iron salt also gradually increases. Therefore, even if the degree of yellowing of the diorganopolysiloxane composition increases with time, the yellowing can be offset by an increase in the amount of bis (2-pyridylthio-1-oxide) iron salt, and the composition Can be prevented or reduced over a long period of time.

  In the present invention, instead of removing the cause of the color change of the diorganopolysiloxane composition, the color change is premised on the premise that the color change is a bis (2-pyridylthio-1-oxide) iron salt. To prevent or reduce the apparent discoloration of the composition as a whole. Therefore, according to the present invention, discoloration during long-term storage of the diorganopolysiloxane composition can be prevented or reduced regardless of the cause of discoloration over time.

  The blending amount of the bis (2-pyridylthio-1-oxide) nonferrous metal salt is 0.0001-0.05% by weight of the composition to be blended, preferably 0.0005-0.02% by weight, 0 0.001 to 0.01% by weight is more preferable, and 0.002 to 0.005% by weight is particularly preferable. When the blending amount is less than 0.0001% by weight, it is difficult to obtain a sufficient discoloration preventing effect. When the blending amount exceeds 0.05% by weight, a relatively large amount of bis (2-pyridylthio-1-oxide) iron is added during blending. Since a salt is formed and the cured product of the organosiloxane composition, particularly the interior of the cured product is colored blue, it is not preferable.

  As described in Examples of JP-A-9-87611, bis (2-pyridylthio-1-oxide) zinc salt is used in a diorganopolysiloxane composition as a fungicide at a concentration of a predetermined amount or more. However, the antifungal property cannot be imparted with a trace amount of 0.05% by weight or less based on the total weight of the composition. In the present invention, a very small amount of bis (2-pyridylthio-1-oxide) zinc salt is not used as an antifungal agent, but as a discoloration preventing or reducing agent for a diorganopolysiloxane composition containing an iron compound.

  The diorganopolysiloxane to be prevented or reduced in color of the present invention contains an iron compound. Examples of the iron compound include iron (II) compounds such as iron (II) oxide and iron (II) sulfide, iron (III) compounds such as iron (III) chloride, iron (III) bromide, iron garnet, and the like. However, iron (II) compounds are preferred, and iron oxide is particularly preferred.

  The iron compound may be added to the diorganopolysiloxane composition as a single component, or may be added to the composition as an impurity in the component blended in the diorganopolysiloxane composition. For example, when an inorganic filler is blended in a diorganopolysiloxane composition, an iron compound can be present in the composition by using an inorganic filler containing an iron compound as an impurity. The compounding amount of the iron compound in the diorganopolysiloxane composition is not particularly limited, but is preferably 10 ppm or more, more preferably 20 ppm or more, still more preferably 50 ppm or more, particularly 100 ppm or more of the total weight of the composition. preferable. Examples of the inorganic filler containing an iron compound include limestone-derived calcium carbonate inherently containing 0.1 to 0.4% by weight of iron oxide as an impurity.

  The type of the iron compound-containing diorganopolysiloxane composition of the present invention is not particularly limited as long as there is a possibility of discoloration over time, but the dealcohol curing type, the deoxime curing type, the deamid curing. A room temperature curable diorganopolysiloxane composition of a condensation reaction curable type such as a mold is preferable. Among these, a dealcohol-curable room temperature curable diorganopolysiloxane composition is particularly preferable in that it does not generate an unpleasant odor and does not corrode metals.

When the composition of the present invention is a dealcohol curable room temperature curable diorganopolysiloxane composition, the composition includes, for example, the following components (A) to (D):
(A) diorganopolysiloxane base (B) iron oxide-containing calcium carbonate powder (C) alkoxysilane or a partial hydrolyzate thereof, and (D) a curing catalyst.

  The (A) component diorganopolysiloxane base is the main component of the diorganopolysiloxane composition, and (A-1) diorganopolysiloxane having hydroxyl groups or hydrolyzable groups at both ends of the molecular chain. Essentially included.

  The hydrolyzable group is not particularly limited, and examples thereof include an alkoxy group, an alkoxysilyl group, an alkoxy-substituted alkoxy group, a ketoximo group, an acyloxy group, and an aminoxy group, and an alkoxy group or an alkoxysilyl group is preferable. . Examples of the alkoxy group include C 1-4 alkoxy groups such as a methoxy group, an ethoxy group, and a propoxy group. Examples of the alkoxysilyl group include a general formula:

｛式中、Ｒ^１は、アルキル基又はアルコキシ置換アルキル基であり；Ｒ^２は一価炭化水素基、ハロゲン化炭化水素基及びシアノアルキル基から選ばれる基であり；ａは０、１又は２であり；Ｙは酸素原子、二価炭化水素基、又は、一般式；

{Wherein, R ¹ is an alkyl group or an alkoxy-substituted alkyl group; R ² is a group selected from a monovalent hydrocarbon group, a halogenated hydrocarbon group, and a cyanoalkyl group; a is 0, 1 or 2 Y is an oxygen atom, a divalent hydrocarbon group, or a general formula;

（式中、Ｒ^２は前記と同じであり；Ｚは二価炭化水素基である）で表される基である｝で表されるアルコキシシリル基が挙げられる。

(Wherein, R ² is the same as above; Z is a divalent hydrocarbon group)}.

  Therefore, as the diorganopolysiloxane of (A-1), for example, the general formula:

（式中、Ｒ^２、ａ及びＹは前記と同じであり；Ｒ³は、Ｒ^２から独立して、一価炭化水素基、ハロゲン化炭化水素基及びシアノアルキル基から選ばれる基であり；ｎは２５℃における粘度が２０〜１，０００，００００ｍＰａ・ｓとなるような整数を表わす）、又は、

Wherein R ² , a and Y are as defined above; R ³ is a group independently selected from R ^{2 and selected} from a monovalent hydrocarbon group, a halogenated hydrocarbon group and a cyanoalkyl group; n represents an integer such that the viscosity at 25 ° C. is 20 to 1,000,0000 mPa · s), or

（式中、Ｒ^１、Ｒ^２、Ｒ^３、ａ、ｎ及びＹは前記と同じである）で示されるジオルガノポリシロキサンを使用することができる。

A diorganopolysiloxane represented by the formula (wherein R ¹ , R ² , R ³ , a, n and Y are the same as described above) can be used.

  Such a method for producing a diorganopolysiloxane is well known, for example, a method in which a diorganopolysiloxane having hydrosilyl groups at both ends of a molecular chain and an alkenyltrialkoxysilane or alkenylalkyldialkoxysilane are subjected to an addition reaction; A method in which a diorganopolysiloxane having an alkenylsilyl group at both ends of a molecular chain and a trialkoxysilane or an alkyldialkoxysilane are subjected to an addition reaction; a diorganopolysiloxane having a hydroxysilyl group at both ends of a molecular chain and a tetraalkoxysilane or an alkyl A method of dealcoholization condensation reaction with trialkoxysilane is mentioned.

  The diorganopolysiloxane base of component (A) is composed of (A-1) a diorganopolysiloxane having hydroxyl groups or hydrolyzable groups at both ends of the molecular chain, and (A-2) hydroxyl groups or hydrolysates at one end of the molecular chain. A diorganopolysiloxane having a decomposable group and / or (A-3) a diorganopolysiloxane having no hydroxyl group or hydrolyzable group at both ends of the molecular chain may be included. By using the component (A-2) and / or the component (A-3) together with the component (A-1), the adhesiveness of the (A) diorganopolysiloxane base is improved and / or after curing. The modulus of the composition can be adjusted by appropriately reducing it. In addition, it is preferable that the viscosity in 25 degreeC of the diorganopolysiloxane base of (A) component is 20-1,000,000 mPa * s, and 1,000-100,000 mPa * s is especially preferable.

  As the diorganopolysiloxane (A-2), for example, a general formula:

（式中、Ｒ^２、Ｒ^３、ａ、ｎ及びＹは前記と同じであり；Ｒ^４はアルキル基又はアルケニル基である）、又は、

(Wherein R ² , R ³ , a, n and Y are the same as above; R ⁴ is an alkyl group or an alkenyl group), or

（各式中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４、ａ、ｎ及びＹは前記と同じである）で示されるジオルガノポリシロキサンを使用することができる。

A diorganopolysiloxane represented by the formula (wherein R ¹ , R ² , R ³ , R ⁴ , a, n and Y are the same as described above) can be used.

  Such a method for producing a diorganopolysiloxane is well known. For example, a diorganopolysiloxane having a monoalkoxysilyl group at the molecular chain terminal and a hydrosilyl group at the other molecular chain terminal and an alkenyltrisiloxane. A method of addition reaction of alkoxysilane or alkenylalkyldialkoxysilane; a diorganopolysiloxane having a monoalkoxysilyl group at the molecular chain end and a vinylsilyl group at the other molecular chain end and trialkoxysilane or alkyldi Addition reaction of alkoxysilane; dealcoholization of diorganopolysiloxane having a monoalkoxysilyl group at the molecular chain end and a silanol group at the other molecular chain terminal and tetraalkoxysilane or alkyltrialkoxysilane Condensation reaction And the like.

  The diorganopolysiloxane having a monoalkoxysilyl group at the end of the molecular chain and having a hydrosilyl group, a vinylsilyl group or a silanol group at the other molecular chain end used in the above production method is, for example, a dialkylalkoxy. It can be obtained by ring-opening polymerization of hexaalkylcyclotrisiloxane using siloxylithium as an initiator and then neutralizing with dialkylchlorosilane, alkenyldialkylchlorosilane or carboxylic acid, respectively.

  As the diorganopolysiloxane of (A-3), for example, the formula:

（式中、Ｒ^３、Ｒ^４、ａ、ｎ及びＹは前記と同じである）で示されるジオルガノポリシロキサンを使用することができる。

(Wherein R ³ , R ⁴ , a, n, and Y are the same as described above) can be used.

  As such a diorganopolysiloxane, for example, a known diorganopolysiloxane having hydrosilyl groups at both ends of the molecular chain is used as it is.

  In each of the above formulas, the alkyl group includes an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, and a butyl group, and a carbon number such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Examples are 3-8 cycloalkyl groups. Examples of the alkoxy group-substituted alkyl group include a C 1-4 alkyl group substituted by a C 1-4 alkoxy group such as a methoxyethyl group, an ethoxyethyl group, a methoxypropyl group, or a methoxybutyl group.

  Examples of the monovalent hydrocarbon group include, in addition to the alkyl group having 1 to 4 carbon atoms and the cycloalkyl group having 3 to 8 carbon atoms, alkenyl having 2 to 4 carbon atoms such as a vinyl group and an allyl group. Groups; aryl groups such as phenyl group, tolyl group, naphthyl group; and aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group and the like. Examples of the halogenated hydrocarbon group include a halogenated alkyl group having 1 to 4 carbon atoms such as a chloromethyl group, a trifluoropropyl group, and a chloropropyl group. Examples of the cyanoalkyl group include C 1-4 alkyl groups substituted with a cyano group such as a β-cyanoethyl group and a γ-cyanopropyl group. Examples of the divalent hydrocarbon group include alkylene groups having 2 to 4 carbon atoms such as a methylene group, a propylene group, and a butylene group.

  And as an alkenyl group, C2-C4 alkenyl groups, such as a vinyl group and an allyl group, are illustrated.

  (A) Diorganopolysiloxane base is (A-1) In addition to diorganopolysiloxane having hydroxyl groups or hydrolyzable groups at both ends of molecular chain, (A-2) Hydroxyl groups or hydrolyzable groups at one end of molecular chain When (A-3) the diorganopolysiloxane which does not have a hydroxyl group or a hydrolysable group at the both ends of a molecular chain contains (A) the whole (A-1) combination The amount is preferably 20-95% by weight, more preferably 30-90% by weight, particularly preferably 40-80% by weight.

  When the component (A-2) is present, the blending amount thereof is preferably 80% by weight or less of the whole (A), more preferably 0.5 to 40% by weight, and particularly preferably 1.0 to 20% by weight. Further, when the component (A-3) is present, the blending amount thereof is preferably 80% by weight or less of the whole (A), more preferably 0.1 to 40% by weight, particularly 0.5 to 15% by weight. preferable.

  The (B) component iron oxide-containing calcium carbonate powder is a calcium carbonate powder containing a small amount of iron oxide, and the iron oxide is present as an impurity or separately added in the calcium carbonate powder. As the component (B), light calcium carbonate and / or heavy calcium carbonate can be used.

The light calcium carbonate that can be used as the component (B) is also called precipitated calcium carbonate, and is generally produced by dehydrating and drying a light calcium carbonate slurry obtained by reacting dense limestone with carbon dioxide. Is done. BET specific surface area Of these 5 m ² / or more, more calcium carbonate is preferably ^{10 m} 2 / g or more. Moreover, since the dispersion | distribution to (A) component is easy and a favorable viscosity characteristic can be obtained, the calcium carbonate powder by which the surface was surface-treated with the fatty acid or rosin acid is preferable. Precipitated calcium carbonate powder is commercially available, for example, from Shiroishi Kogyo Co., Ltd. under the trade name Hakuenka CC, and from Maruo Calcium Co., Ltd. under the trade name Calfine 200, and is available from the market.

The heavy calcium carbonate that can be used as the component (B) is also called ground calcium carbonate, and is generally produced by grinding white limestone and classifying the obtained ground product. Among these, calcium carbonate having a BET specific surface area of 8 m ² / g or less is preferable. Moreover, since the dispersion | distribution to (A) component is easy and a favorable viscosity characteristic can be obtained, the calcium carbonate powder by which the surface was surface-treated with the fatty acid or rosin acid is preferable. Furthermore, what has oil absorption (JISK5101) in the range of 15-40 ml / 100g is preferable. The ground calcium carbonate is commercially available from Toyo Fine Chemical Co., Ltd. under the trade name Whiten P-30 and from Maruo Calcium Co., Ltd. under the trade name Nanox # 30, and is available from the market.

  (B) The compounding quantity of a component needs to be 1-300 weight part with respect to 100 weight part of (A) component, 5-200 weight part is preferable and 10-150 weight part is more preferable. When the blending amount is less than 1 part by weight, the mechanical strength of the composition is lowered, and the viscosity is lowered to make handling difficult. On the other hand, when it exceeds 300 parts by weight, the viscosity becomes too high and the usability is poor. In addition, when using both light calcium carbonate and heavy calcium carbonate as a component (B), these ratios are weight ratios, and light calcium carbonate: heavy calcium carbonate = 1.00: 1.00-1 0.000: 0.01, more preferably in the range of 1.00: 0.70 to 1.00: 0.05, and 1.00: 0.40 to 1.00: 0. More preferably, it is within the range of 0.03.

Specific types of hydrolyzable silane or partial hydrolyzate thereof as the component (C) is not particularly limited but, for example, the general formula: R 5 _{^b SiX} ^4-b
Wherein R ⁵ is an alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group; a monovalent hydrocarbon group exemplified by an alkenyl group such as a vinyl group or an allyl group: X is a methoxy group, ethoxy An alkoxy group such as a methoxyethyl group, an ethoxyethyl group, a methoxypropyl group, or a methoxybutyl group; an isopropenoxy group, a 1-ethyl-2-methylvinyloxy group, or the like; An alkenyloxy group; a ketoximo group such as a dimethylketoximo group or a methylethylketoximo group; an acyloxy group such as an acetoxy group, a propionoxy group, a butyroyloxy group, or a benzoyloxy group; an amino group such as a dimethylaminoxy group or a diethylamino group; An aminoxy group such as a xoxy group or a diethylaminoxy group; N A hydrolyzable silane represented by a hydrolyzable group exemplified by amide groups such as -methylacetamide group, N-ethylacetamide group, N-methylbenzamide group, etc., and b is an integer of 0-2) or The partial hydrolysis condensate can be used. In the above general formula, X is preferably an alkoxy group, an alkoxy group-substituted alkyl group or a ketoximo group. Further, b is preferably 0 or 1. In the case of b = 2, that is, when a bifunctional hydrolyzable silane is blended, it becomes possible to reduce the modulus of the adhesive after curing, so that it may be used as necessary.

Examples of the component (C) include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxylane, ethyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, Trifunctional alkoxysilanes such as methyltrimethoxyethoxysilane; tetrafunctional alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane; methyltris (methoxyethoxy) silane, methyltripropenoxysilane, methyltriacetoxysilane, vinyltriacetoxysilane, methyltri (butanoxime) silane, vinyltri (butanoxime) silane, trimethoxy (butanoxime) silane, phenyltri (butanoxime) silane, tetra ( Tanoxime) silane, 3,3,3-trifluoropropyl (butanoxime) silane, 3-chloropropyl (butanoxime) silane, methyltri (propanoxime) silane, methyltri (pentanoxime) silane, methyltri (isopentanoxime) silane, vinyl ( Examples thereof include cyclopentam) silane, methyltri (cyclohexanoxime) silane, and partial hydrolysates thereof.

  (C) As a hydrolysable silane or its partial hydrolyzate component, only one type of compound may be used, or two or more types may be mixed and used. (C) When using a component, the compounding quantity is the range of 0.5-30 weight part with respect to 100 weight part of (A) component, and the range of 1-25 weight part is preferable. When the blending amount is too small, the composition of the present invention tends to be insufficiently cured, and also thickens during storage and easily gels. On the other hand, if the amount is too large, curing is slowed, and the cost is disadvantageous.

  As the curing catalyst for component (D), organic compounds such as tetraisopropoxy titanium, tetra-t-butoxy titanium, titanium di (isopropoxy) bis (ethylacetoacetate), titanium di (isopropoxy) bis (acetylacetonate), etc. Titanium compounds; organotin compounds such as dibutyltin dilaurate, dibutyltin bisacetylacetonate and tin octylate; metal dicarboxylates such as lead dioctylate; organozirconium compounds such as zirconium tetraacetylacetonate; aluminum triacetylacetonate and the like Organoaluminum compounds; amines such as hydroxylamine and tributylamine can be used. Among these, an organic titanium compound is preferable. The blending amount of the curing catalyst component is preferably in the range of 0.001 to 10 parts by weight, more preferably in the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the component (A). If the blending amount is too small, the curing of the composition may be greatly delayed. On the other hand, if the blending amount is too large, the storage stability may be deteriorated, or the elasticity after curing may be impaired.

  In addition to these components, the composition of the present invention includes silane couplings such as amino group-containing organotrialkoxysilane, epoxy group-containing organotrialkoxysilane, and mercapto-containing organotrialkoxysilane. An agent may be added. These silane coupling agents may be used alone or in combination of two or more silane coupling agents. Alternatively, a reaction mixture of an organic amine or amino group-containing organotrialkoxysilane and an epoxy group-containing organotrialkoxysilane may be used. Among the above components, in particular, a silane coupling agent containing an amino group is highly effective in improving the adhesion.

  In addition to these components, in the composition of the present invention, various compounding agents known to be blended in a room temperature curable silicone rubber composition, for example, fumed silica, precipitated silica, quartz fine powder, fumes Inorganic fillers such as titanium dioxide, diatomaceous earth, aluminum hydroxide powder, alumina powder, magnesium powder, zinc oxide powder, zinc carbonate powder; organic solvents, fungicides, flame retardants, heat-resistant agents, plasticizers, thixotropic properties Mixing an agent, an adhesion-imparting agent, a curing accelerator, and a pigment may be performed as long as the object of the present invention is not impaired.

  The composition of the present invention can be easily produced, for example, by uniformly mixing the above-mentioned components (A)-(D) and, if necessary, the above-mentioned various other additives while blocking moisture. . The composition of the present invention may be a so-called one-component curable type or a two-component curable type, but is preferably a one-component curable type from the viewpoint of workability. When the composition of the present invention is a one-component curable type, the composition of the present invention is enclosed and stored in a container such as an airtight cartridge, and is used after being removed from the container and exposed to air during use. . As a result, the one-component curable diorganopolysiloxane composition of the present invention is cured by moisture present in the air and becomes a silicone rubber having rubber elasticity.

  Hereinafter, the present invention will be described using examples and comparative examples.

  In the examples and comparative examples, the viscosity and color are measured by the following methods.

<Viscosity measurement method>
Using a viscoelasticity measuring instrument (AR-500 rheometer) manufactured by T.A. Instruments Japan Co., Ltd., after pre-shearing for 1 minute at a shear rate of 20 / s, a geometry of 20 cm 2 ° and 100 The viscosity was measured under the condition of a shear rate of / s.

<Color measurement method>
The color was measured by a L ^* a ^* b ^* color system using a spectrophotometer (MINOLTA CM2002) manufactured by Minolta. The L ^* axis defines brightness, the a ^* axis defines the red / green direction, and the b ^* axis defines the yellow / blue direction. The L ^* axis is 0 (black) to 100 (white), the a ^* axis is represented by red in the + direction, green in the − direction, the b ^* axis is represented by yellow in the + direction, and blue in the − direction.

<Method for producing cured sheet>
The room temperature-cured silicone rubber composition was uniformly cast on a Teflon (registered trademark) sheet so as to have a thickness of 2 mm, and cured under conditions of 25 ° C. and 50% RH for 7 days to obtain a cured sheet. In addition, the surface which was in contact with air | atmosphere at the time of hardened sheet preparation was made into the surface, and the surface which was in contact with the Teflon (trademark) sheet was made into the back surface.

[Example 1]
65 parts by weight of α, ω-di (triethoxysilylethylene) dimethylpolysiloxane having a viscosity of 60,000 mPa · s represented by the following formula 1, α, ω-dimethyldimethylpolysiloxane having a viscosity of 100 mPa · s represented by the following formula 2 35 parts by weight, 100 parts by weight of light calcium carbonate containing 0.16% by weight of iron oxide at a BET specific surface area of 18 m ² / g whose surface was treated with fatty acids, and a BET specific surface area of 5.8 m whose surface was treated with fatty acids 25 parts by weight of heavy calcium carbonate containing 0.19% by weight of iron oxide at ² / g, 2.8 parts by weight of methyltrimethoxysilane and 2.8 parts by weight of isobutyltrimethoxysilane as a crosslinking agent, and titanium as a curing catalyst 2.5 parts by weight of di (isopropoxy) -bis (ethyl acetoacetate), γ-aminopropyltrimeth as an adhesion promoter Reaction mixture of silane and γ-glycidoxypropyltrimethoxysilane (γ-aminopropyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane were mixed at a molar ratio of 1: 2, and then at room temperature and humidity 1.0 part by weight) was added and mixed until it became uniform under moisture shielding.

  Next, composition 0 in which 10 parts by weight of (2-pyridylthio-1-oxide) zinc salt (zinc pyrithione) represented by the following formula 3 and 90 parts by weight of terminal trimethylsiloxy-capped polydimethylsiloxane having a viscosity of 3,000 mPa · s were mixed. A room temperature curable silicone rubber composition was prepared by mixing 0.001 part by weight until moisture was cut off and uniform. The composition of the room temperature curable silicone rubber composition is shown in Table 1.

  This room temperature curable silicone rubber composition was filled in a high density polyethylene cartridge, stored in an oven at 25 ° C. and 50% RH for 7 days, and further stored in an oven at 40 ° C. and 95% RH for 18 weeks. A cured sheet was prepared after 7 days and 18 weeks, and the color of the front and back surfaces of the sheet was measured to determine the color difference. The results are shown in Table 2 and Table 3, respectively.

Formula 1:

（式中、Ｍｅはメチル基であり、Ｅｔはエチル基である。ｎは２５℃における粘度が２０〜１，０００，０００ｍＰａ・ｓとなるような整数を表わす）
式２：

(In the formula, Me is a methyl group and Et is an ethyl group. N represents an integer such that the viscosity at 25 ° C. is 20 to 1,000,000 mPa · s)
Formula 2:

（式中、Ｍｅはメチル基である。ｎは２５℃における粘度が２０〜１，０００，０００ｍＰａ・ｓとなるような整数を表わす）
式３：

(In the formula, Me is a methyl group. N represents an integer having a viscosity of 20 to 1,000,000 mPa · s at 25 ° C.)
Formula 3:

[Example 2]
In Example 1, the addition amount of the composition in which 10 parts by weight of (2-pyridylthio-1-oxide) zinc salt (zinc pyrithione) and 90 parts by weight of a terminal trimethylsiloxy-capped polydimethylsiloxane having a viscosity of 3,000 mPa · s was mixed was 0. A room temperature curable silicone rubber composition was produced in the same manner as in Example 1 except that the content was 0.02 part by weight. The composition of the room temperature curable silicone rubber composition is shown in Table 1. With respect to this room temperature curable silicone rubber composition, cured sheets were prepared in the same manner as in Example 1 after 7 days and 18 weeks, and the color of the front and back surfaces of the sheet was measured to determine the color difference. The results are shown in Table 2 and Table 3, respectively.

[Example 3]
In Example 1, the addition amount of the composition in which 10 parts by weight of (2-pyridylthio-1-oxide) zinc salt (zinc pyrithione) and 90 parts by weight of a terminal trimethylsiloxy-capped polydimethylsiloxane having a viscosity of 3,000 mPa · s was mixed was 0. A room temperature curable silicone rubber composition was produced in the same manner as in Example 1 except that the amount was 0.05 parts by weight. The composition of the room temperature curable silicone rubber composition is shown in Table 1. With respect to this room temperature curable silicone rubber composition, cured sheets were prepared in the same manner as in Example 1 after 7 days and 18 weeks, and the color of the front and back surfaces of the sheet was measured to determine the color difference. The results are shown in Table 2 and Table 3, respectively.

[Example 4]
In Example 1, the addition amount of the composition in which 10 parts by weight of (2-pyridylthio-1-oxide) zinc salt (zinc pyrithione) and 90 parts by weight of terminal trimethylsiloxy-capped polydimethylsiloxane having a viscosity of 3,000 mPa · s were mixed was 0. A room temperature curable silicone rubber composition was produced in the same manner as in Example 1 except that the amount was 0.08 parts by weight. The composition of the room temperature curable silicone rubber composition is shown in Table 1. With respect to this room temperature curable silicone rubber composition, cured sheets were prepared in the same manner as in Example 1 after 7 days and 18 weeks, and the color of the front and back surfaces of the sheet was measured to determine the color difference. The results are shown in Table 2 and Table 3, respectively.

[Example 5]
In Example 1, the addition amount of the composition in which 10 parts by weight of (2-pyridylthio-1-oxide) zinc salt (zinc pyrithione) and 90 parts by weight of a terminal trimethylsiloxy-capped polydimethylsiloxane having a viscosity of 3,000 mPa · s was mixed was 0. A room temperature curable silicone rubber composition was produced in the same manner as in Example 1 except that the amount was changed to 12 parts by weight. The composition of the room temperature curable silicone rubber composition is shown in Table 1. With respect to this room temperature curable silicone rubber composition, cured sheets were prepared in the same manner as in Example 1 after 7 days and 18 weeks, and the color of the front and back surfaces of the sheet was measured to determine the color difference. The results are shown in Table 2 and Table 3, respectively.

[Example 6]
In Example 1, the addition amount of the composition in which 10 parts by weight of (2-pyridylthio-1-oxide) zinc salt (zinc pyrithione) and 90 parts by weight of a terminal trimethylsiloxy-capped polydimethylsiloxane having a viscosity of 3,000 mPa · s was mixed was 1 A room temperature curable silicone rubber composition was produced in the same manner as in Example 1 except that the amount was changed to .17 parts by weight. The composition of the room temperature curable silicone rubber composition is shown in Table 1. With respect to this room temperature curable silicone rubber composition, cured sheets were prepared in the same manner as in Example 1 after 7 days and 18 weeks, and the color of the front and back surfaces of the sheet was measured to determine the color difference. The results are shown in Table 2 and Table 3, respectively.

[Comparative Example 1]
In Example 1, except that a composition in which 10 parts by weight of (2-pyridylthio-1-monooxide) zinc salt (zinc pyrithione) and 90 parts by weight of a terminal trimethylsiloxy-capped polydimethylsiloxane having a viscosity of 3,000 mPa · s are not added is not added. A room temperature curable silicone rubber composition was produced in the same manner as in Example 1. The composition of the room temperature curable silicone rubber composition is shown in Table 1. With respect to this room temperature curable silicone rubber composition, cured sheets were prepared in the same manner as in Example 1 after 7 days and 18 weeks, and the color of the front and back surfaces of the sheet was measured to determine the color difference. The results are shown in Table 2 and Table 3, respectively.

Claims (7)

An iron oxide-containing diorganopolysiloxane composition comprising 0.0001-0.05% by weight of bis (2-pyridylthio-1-oxide) non-ferrous metal salt based on the total weight of the composition to prevent discoloration or A composition comprising as a discoloration reducing agent. The composition according to claim 1, which is a condensation reaction curable diorganopolysiloxane composition. The composition according to claim 1 or 2, comprising an inorganic filler, wherein the iron oxide is present in the inorganic filler. The composition according to claim 3, wherein the inorganic filler is an iron oxide-containing calcium carbonate powder. (A) 100 parts by weight of diorganopolysiloxane base containing the following components (A-1) 20-100% by weight of diorganopolysiloxane having hydroxyl groups or hydrolyzable groups at both ends of the molecular chain
(A-2) 0-80% by weight of diorganopolysiloxane having a hydroxyl group or a hydrolyzable group at one end of the molecular chain
(A-3) Diorganopolysiloxane having no hydroxyl group or hydrolyzable group at both ends of the molecular chain 0-80% by weight
(B) 1 to 300 parts by weight of iron carbonate-containing calcium carbonate powder,
The composition according to claim 4, further comprising 0.5 to 30 parts by weight of (C) hydrolyzable silane or a partial hydrolyzate thereof, and (D) 0.001 to 10 parts by weight of a curing catalyst. The composition according to claim 5, wherein the curing catalyst is an organic titanium compound. The composition according to any one of claims 1 to 6, wherein the bis (2-pyridylthio-1-oxide) non-ferrous metal salt is a bis (2-pyridylthio-1-oxide) zinc salt.