JP4737446B2 - Method for producing platinum complex catalyst - Google Patents

Description

  The present invention relates to a method for producing a platinum complex catalyst having improved storage stability of a platinum-vinylsiloxane complex useful as a hydrosilylation catalyst.

  Conventionally, the known hydrosilylation reaction represented by the following formula is very useful in many fields using a curable silicone composition.

In this hydrosilylation reaction, a SiH group-containing compound such as organohydrogensiloxane and a CH ₂ ═CH group-containing compound such as vinyl group-containing organopolysiloxane are reacted in the presence of a platinum catalyst. The platinum catalyst initially used was in the form of fine particles of a platinum halide compound or metal platinum. As an example, Spirous chloroplatinic acid of US Pat. No. 2,823,218 (Patent Document 1) was used. And Bailey's US Pat. No. 2,970,150 (Patent Document 2). Since then, the activity of the catalyst has been improved from the viewpoint of economic efficiency, and platinum-vinylsiloxane complexes have been frequently used. However, this platinum-vinylsiloxane complex is disclosed in Japanese Patent Publication No. 55-423 (Patent Document 3) that halogen ions in the complex adversely affect the catalytic activity. Further, it is shown in Japanese Patent Publication No. 46-28795 (Patent Document 4), Japanese Patent Publication No. 47-23679 (Patent Document 5) that the platinum-vinylsiloxane complex is decomposed by contact with water, It is proposed to store the platinum-vinylsiloxane complex at -50 ° C to 50 ° C.

  However, the present inventors have often found that the above-described platinum-vinylsiloxane complex is darkened and settled in the summer, which may cause problems in storage and use.

  Conventionally, the platinum-vinylsiloxane complex has been pursued to improve the activity by reducing the remaining halogen as much as possible, and Japanese Patent Application Laid-Open No. 56-136655 (Patent Document 6) or the like substantially does not contain an inorganic halogen. Is disclosed. However, JP-A-3-36573 (Patent Document 7) discloses a method for producing a complex which is highly active and excellent in storage stability even when an inorganic halogen is present in which a halogen of 1 gram atom per 1 gram atom of platinum is present. However, it has also been confirmed that the hydrosilylation catalyst obtained by the above-described method also lacks the storage stability at high temperatures, the appearance becomes black, and gradually precipitates, resulting in a decrease in catalytic activity.

  Therefore, the platinum-vinylsiloxane complex has the above-mentioned problems, that is, it is sensitive to heat and moisture and lacks storage stability, and tends to cause a decrease in catalytic activity due to coloring and black precipitation. There is a strong demand for the development of a method that solves the problem of troubles occurring particularly in summer and improves the storage stability without reducing the activity of the catalyst.

U.S. Pat. No. 2,823,218 U.S. Pat. No. 2,970,150 Japanese Patent Publication No.55-423 Japanese Examined Patent Publication No. 46-28795 Japanese Patent Publication No. 47-23679 JP 56-136655 A JP-A-3-36573 JP-A-9-141107

  An object of the present invention is to provide a method for producing a platinum complex catalyst in which deterioration of the catalyst with the lapse of time of heating can be prevented, the catalyst can be prevented from blackening and sedimentation, and no adverse effects on the catalyst activity can occur.

  As a result of intensive studies on a method for improving the storage stability of a platinum-vinylsiloxane complex which is a highly active hydrosilylation catalyst, the present inventors have determined that a low molecular weight chain or cyclic vinyl group-containing siloxane is a vinyl group / platinum atom. By adding an amount of 0.5 to 10 mol / atom in the ratio of the catalyst, deterioration of the catalyst over time can be prevented, the catalyst can be prevented from blackening and sedimentation, and there is almost no adverse effect on the catalyst activity. It was confirmed that local gel generation of the silicone composition during addition of the catalyst could be suppressed, and the present invention was completed.

  The present applicant has proposed a platinum catalyst composition obtained by mixing a platinum-vinylsiloxane complex with a vinyl group-containing organopolysiloxane represented by the following formula (i) and subjecting it to a heat treatment (Japanese Patent Laid-Open No. Hei 9- No. 141107: Patent Document 8).

（式中、Ｒは１価炭化水素基を示す。ｘ，ｙは一分子中のケイ素原子数を１０〜５０個とする数であるが、分子中のケイ素原子数に対するｘの割合は１０〜５０モル％である。）

(In the formula, R represents a monovalent hydrocarbon group. X and y are numbers that make 10 to 50 silicon atoms in one molecule, but the ratio of x to the number of silicon atoms in the molecule is 10 to 10). 50 mol%)

  This platinum catalyst composition is stable even after being stored at a high temperature for a long period of time, and effectively exhibits the effect even after storage. However, the platinum catalyst composition has 10 or more silicon atoms like the organopolysiloxane of the formula (i). It is not a low molecular weight, particularly a low molecular weight vinyl group-containing organopolysiloxane having 6 or less silicon atoms represented by the formulas (1) and (2) described later, and this is mixed with a platinum-vinylsiloxane complex. Alone has been found to have sufficient storage stability.

  According to the present invention, deterioration of the catalyst over time can be prevented, the catalyst can be prevented from blackening and sedimentation, and no adverse effect on the catalyst activity can occur.

  Hereinafter, the present invention will be described in more detail.

  The platinum complex catalyst of the present invention is obtained by adding a specific amount of a low molecular weight linear or cyclic vinylsiloxane to a platinum-vinylsiloxane complex.

  Here, as the platinum-vinylsiloxane complex, for example, a known one disclosed in Japanese Patent Publication No. 47-23679 (Patent Document 5) or the like can be used, and it can be produced by a conventional method.

  In addition, as vinylsiloxane, what is shown by following formula (3), (4) can be used, for example.

（式中、Ｒは互いに同一又は異種の炭素数１〜８の非置換又は置換１価炭化水素基を示し、ｂは１以上の整数、ａは０以上の整数であるが、ａ＋ｂは３〜８である。）

(In the formula, R represents the same or different C1-C8 unsubstituted or substituted monovalent hydrocarbon group, b is an integer of 1 or more, a is an integer of 0 or more, but a + b is 3 to 3. 8)

Here, examples of R include the same groups as R ¹ and R ² described later.

  In addition, as the linear or cyclic low molecular weight vinyl siloxane added to the platinum-vinyl siloxane complex, those represented by the following general formula (1) or (2) are preferably used.

（式中、Ｒ¹，Ｒ²はそれぞれ独立に１価の脂肪族及び芳香族炭化水素基から選択され、ｎは０〜５、ｍは１〜６の正数で、３≦ｎ＋ｍ≦６、ｐ，ｑはそれぞれ０〜４の正数で、０≦ｐ＋ｑ≦４である。）

Wherein R ¹ and R ² are each independently selected from monovalent aliphatic and aromatic hydrocarbon groups, n is 0-5, m is a positive number 1-6, 3 ≦ n + m ≦ 6, p and q are each a positive number of 0 to 4, and 0 ≦ p + q ≦ 4.)

Here, as the aliphatic hydrocarbon group for R ¹ and R ² , those having 1 to 10 carbon atoms, particularly those having 1 to 8 carbon atoms are preferable, and alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, cyclohexyl and octyl, A cycloalkyl group is mentioned, The thing which has an aliphatic unsaturated bond is not included. Examples of the aromatic hydrocarbon group include those having 6 to 12 carbon atoms, particularly 6 to 10 carbon atoms, and aryl groups such as phenyl and tolyl, aralkyl groups such as benzyl group and phenylethyl group.

  Examples of such low molecular weight vinyl siloxanes include sym-divinyltetramethyldisiloxane, hexavinyldisiloxane, sym-phenylmethylvinyldisiloxane, methylvinyltrisiloxane, and methylvinyltetrasiloxane.

  As a result of examining the abundance ratio of the low molecular weight vinyl siloxane and the platinum atom in detail, the vinyl group unit may be used in the range of 0.5 to 10 mol per gram atom of platinum, and preferably in the range of 1 to 5 mol. When the amount is less than 0.5 mol, the effect of preventing blackening is poor. When the amount exceeds 10 mol, the prevention effect is sufficient, but the catalytic activity is conspicuously lowered, and the use is focused on the curing speed, for example, the production of release paper In addition, it is unsuitable for applications that require curing in a short time.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In the following examples,% indicates% by weight.

[Example 1, comparative example]
12.0 g of chloroplatinic acid H ₂ PtCl ₆ · 6H ₂ O (37.6% platinum) is placed in a 100 ml reaction flask equipped with a reflux condenser, thermometer and stirrer, then 37.5 g of ethanol and sym-divinyl 20.7 g of tetramethyldisiloxane was added. After heating and reacting at 70 ° C. for 50 hours, the reaction mixture was neutralized for 2 hours by gradually adding 13 g of sodium bicarbonate while stirring at room temperature. The reaction mixture was filtered with suction, and the filtrate was distilled off under reduced pressure. Ethanol and excess sym-divinyltetramethyldisiloxane were substantially removed, and then diluted with toluene to a total amount of 900 g (containing 0.5% platinum). , Cl / Pt = 0.30) [platinum-vinylsiloxane complex solution A (hereinafter abbreviated as [A])].

  A colorless 50 ml sample bottle containing 30 g of [A] and [A] added with 0.1%, 0.5, 1.0, and 4.0% of sym-divinyltetramethyldisiloxane (VS-1), respectively. The two were taken and left at 25 ° C. and 50 ° C., and the appearance and catalytic activity were examined over time. The results are shown in Tables 1 and 2.

  The catalytic activity is 1% (with KS847H) added to a 5% toluene solution of KS847H (manufactured by Shin-Etsu Chemical Co., Ltd., trade name, silicone content 30%), coated on polyethylene laminated paper, 100 ° C. And examined by setting time.

  As shown in Tables 1 and 2, it can be seen that the samples of the present invention have no change in appearance and no decrease in catalytic activity.

[Example 2]
Instead of adding sym-divinyltetramethyldisiloxane to the platinum-vinylsiloxane complex solution [A] of Example 1, hexavinyldisiloxane (VS-2), sym-phenylmethylvinyldisiloxane (VS-3), methyl Vinyl tetrasiloxane (VS-4) was added in the same manner to each [A] in an amount of 0.5% by weight, and the change with time at 25 ° C. and 50 ° C. was examined. Table 3 shows the appearance and Table 4 shows the results of curability (catalytic activity).

Claims (3)

A low molecular weight linear or cyclic vinylsiloxane represented by the following general formula (1) or (2) is converted into a vinyl group / platinum atom in the platinum-vinylsiloxane complex represented by the following formula (3) or (4). A platinum complex catalyst production method, wherein the ratio is 0.5 to 10 mol / atom.

(In the formula, R represents the same or different C1-C8 unsubstituted or substituted monovalent hydrocarbon group, b is an integer of 1 or more, a is an integer of 0 or more, but a + b is 3 to 3. 8)

Wherein R ¹ and R ² are each independently selected from monovalent aliphatic and aromatic hydrocarbon groups, n is 0-5, m is a positive number 1-6, 3 ≦ n + m ≦ 6, p and q are each a positive number of 0 to 4, and 0 ≦ p + q ≦ 4.) Platinum - After removing the excess vinylsiloxane complex from the reaction mixture after the vinyl siloxane complex manufacturing, general formula (1) or of claim 1, wherein the platinum complex catalyst, characterized by adding a vinyl siloxane (2) Production method. After reacting chloroplatinic acid with sym-divinyltetramethyldisiloxane, excess sym-divinyltetramethyldisiloxane is removed from the reaction mixture, which is then added to sym-divinyltetramethyldisiloxane, hexavinyldisiloxane, sym. - phenylmethyl vinyl disiloxane, or a manufacturing method of the platinum complex catalyst of claim 1, wherein the addition of methyl vinyl tetrasiloxane.