JP3207905B2 - Polymerization catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to catalysts and, more particularly, to catalysts used in polymerization reactions, especially for the polymerization of organosiloxanes.

[0002]

2. Description of the Related Art The polymerization or copolymerization of organosiloxanes has been known in the art and is a well-known process in the production of commercially available siloxanes. Organopolysiloxanes have been prepared, for example, by contacting low viscosity organosiloxanes, especially cyclic polysiloxanes, low viscosity siloxanols or mixtures thereof in the presence of an acidic or basic catalyst. For example, organopolysiloxanes can be prepared by the condensation of organosiloxanes having a reactive group at the terminal silicon atom, such as silicon-bonded hydroxyl groups, silicon-bonded hydrocarbonoxy groups, and mixtures of two or more thereof. Further, the organopolysiloxane can be produced by rearrangement of a linear and / or cyclic organosiloxane. For each polymerization method,
Various catalysts have been developed, some of which are more effective than others. Known catalysts for this type of polymerization reaction include sulfuric acid, hydrochloric acid, Lewis acids, sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, tetrabutylphosphonium silanolate and amines.

[0003] Many patent applications disclose phosphonitrile halide catalysts. GB 765 744 discloses that preferred phosphonitrile halides for the polymerization of liquid organosiloxanes having an average of 1.9 to 2.1 silicon-bonded organic residues per silicon atom have the formula:
(PNCl ₂ ) _n , wherein n is an integer of at least 3, and most preferably 3 to 6. This method is stated to be particularly valuable for the production of polymerized organosiloxanes used in the production of silicone rubber.

GB 910 513 discloses the preparation of a liquid mixture of a phosphonitrile halide with a triorganosilyl end-blocked diorganopolysiloxane and a hydroxyl-terminated diorganopolysiloxane having a viscosity of from 1 to 10,000 mm ² / s. And then contacting the mixture with a stream of air at room temperature until the viscosity is stable, and thereafter contacting the mixture with a stream of air at a temperature of 100-200 ° C. until the viscosity is stable. A phosphonitrile halide catalyst for use in a method for producing an organopolysiloxane oil is disclosed.

In US Pat. No. 3,549,680,
In the rearrangement reaction, for example, an organohalogensiloxane compound having at least one halogen atom per molecule bonded to silicon and a halogen-free organosiloxane having a viscosity of 100,000 mm ² / s or less are mixed with phosphonitrile halide. A phosphonitrile halide catalyst is used in a method for producing an organohalogenosilicone compound consisting of

[0006] EP 319 978 describes:
Each terminal unit comprising reacting the cyclic diorganopolysiloxane and / or diorganochlorosilane hydrolysis product with diorganochlorosilane and then treating with water or an aqueous solution to separate the low boiling substituent and the aqueous phase A chlorophosphonitrile catalyst for use in a method for producing a diorganopolysiloxane having silicon-bonded hydroxyl groups is disclosed. Research continues on catalysts having improved activity in the polymerization of organosiloxanes.

[0007]

SUMMARY OF THE INVENTION The present inventors have determined that if a phosphonitrile catalyst contains certain Lewis acid groups,
It has been found that an improved catalyst for the production of organopolysiloxanes is obtained. According to the present invention, the following general formula: [X (PX ₂ = N) _n PX ₃ ] ⁺ [MX _{(v−t + 1)} R _t ] ⁻ (1) (where X represents a halogen atom) , M has an electronegativity of 1.0 to 2.0 on the Pauling scale
Selected from the group consisting of Al, B, Be, Mg, Sb and Si
A Bareru element, R is an alkyl group having carbon atoms up to 12, n has a value of 1 to 6, v is the valence or oxidation state of M, is 0 ≦ t <v. The present invention provides a phosphonitrile halide catalyst for use in the polymerization of an organosiloxane, the catalyst comprising:

Some phosphonitrile halide compounds useful as polymerization catalysts for organosiloxanes have been described in the literature, but their use as catalysts was not previously known. U.S. Patent No.
3,449,091 discloses a metal halide-modified phosphonitrile chloride polymer composition useful as a high temperature lubricant. The disclosed substances have the general formula: [Cl
(PCl ₂ = N) _n PCl ₃ ] ⁺ [EX _{(v + 1)} ] ⁻ (where E is an element having an electronegativity of 1.2 to 2 and a maximum of 2.5 in electronegativity. X is a halogen, v is the valency of element E, and n is 1 to 10). Illustrative elements E are Zn, Al, B, Ti, Sn, Sb, Th and Fe. While some of the compounds described are useful as catalysts for the polymerization of organosiloxanes, not all are effective and some compounds are less preferred than others. There is no technique to show that some of these compounds are useful as catalysts, and there is no indication that some of these compounds are useful as catalysts for the polymerization of organosiloxanes.

The catalyst of the present invention has an anionic moiety derived from a Lewis acid and a cationic phosphonitrile moiety. The phosphonitrile moiety has the general formula: [X (PX ₂
= N) _n PX ₃ ] ⁺ (wherein n is an integer having a value of 1 to 6), which is a linear low-molecular or high-molecular phosphonitrile halide. The halogen X is preferably a halide atom. Phosphonitrile halide cation moieties where the value of n is greater than 6 are not suitable as catalysts. Most preferred are phosphonitrile halide moieties wherein n is 2-4. Since it is difficult to separate polymeric phosphonitrile halides having various n's, mixtures are often used. It is particularly preferred that the amount of phosphonitrile halide polymer where n is 2 is as high as possible to provide the highest activity catalyst. Particular preference is given to catalysts consisting essentially of the compounds according to the invention in which the value of n is 2.

The anionic portion of the catalyst is derived from a Lewis acid and has the general formula: [MX _{(v-t + 1)} R _t ] ^- . The value of t is preferably zero, but can include alkyl groups. Preferably, the Lewis acid based anion comprises the same halide X as the halide of the phosphonitrile cation moiety, ie most preferably chlorine. The element M in the Lewis acid moiety has an electronegativity value of 1 on the Pauling scale.
~ 2, preferably 1.2-1.9, most preferably 1.
It is an electropositive element having a value of 5-1.9. Suitable elements are Periodic Tables Ib, IIa, IIb, IIIa, IVa, IVb,
Found in the Va, Vb, VIb, VIIb and VIII families. These include Al, B, Be, Mg, Sb and Si. The difference between the electronegativity values of the phosphorus atom and the M element of the phosphonitrile portion of the catalyst is preferably as large as possible within the preferred range, and larger values give improved catalytic activity. The presence of an anionic Lewis acid-based moiety in the catalyst improves the catalytic activity of the catalyst in organosiloxane polymerization reactions. It also helps to make the catalyst itself more stable, so that polymerization and cyclization with other phosphonitrile compounds is prevented even at high temperatures.

Particularly suitable compounds are those in which the moieties derived from Lewis acids are based on antimony, in particular SbCl ₃ and SbCl ₅ . Examples of suitable catalysts of this type are:
_{Formula: [Cl 3 P = N- (} PCl 2 = N) s -PCl 3]
⁺ [SbCl ₆ ] ⁻ (where s is a value of 1 to 4). Other suitable compounds are those in which the moieties derived from Lewis acids are based on aluminum.
The phosphonitrile halide catalyst of the present invention can be produced by the reaction of phosphorus pentahalide, ammonium halide and Lewis acid. The catalyst is present in the presence of an aromatic hydrocarbon as an inert solvent, or more preferably in the presence of a halogenated aliphatic or aromatic hydrocarbon, for example toluene, sym-tetrachloroethane or 1,2,4-trichlorobenzene. It is preferably prepared by reacting a phosphorus pentahalide, such as phosphorus pentachloride, an ammonium halide, such as ammonium chloride, and a selected Lewis acid.

Suitable Lewis acids are based on the electropositive element M which has an electronegativity value according to the Pauling scale of 1-2. An example of a suitable Lewis acid is SbC
_{l 3, SbCl 5, AlCl 3} , SiCl 4, MgCl 2,
BCl ₃ and BF ₃ . The reaction can be carried out at a temperature of 100-220 ° C., then the reaction product is separated from solids and volatile components, and the liquid reaction product is isolated. 100
If the temperature is lower than 0 ° C, the reaction does not proceed or is too slow to be carried out economically. A mere mixture of reactants does not give a satisfactory rate of polymerization. Temperatures above 220 ° C. can be used if pressure is applied to maintain the solvent in the system, but are generally not recommended because at elevated temperatures the product tends to darken. A preferred temperature range is the reflux temperature of the solvent used in the reaction, e.g.

The reactants may be added in any order,
It is preferred that no Lewis acid be added before introducing the appropriate solvent into the reactor. The reactants can be contacted for any time, but a period of 2 to 10 hours is preferred. It is preferable to continue the reaction for a period of 6 hours or more. It is preferred to react the reactants until a substantial amount of the phosphonitrile halide formed is an oligomer greater than two units. This can be easily observed since the phosphonitrile halide dimer is not dissolved in the solvent.

If the residual reaction product contains a dimer, the dimer is separated and refluxed in a solvent, preferably in the presence of a trace amount of ammonium halide, to convert it to a higher oligomer. Is preferred. As the reaction conditions, it is preferable to employ conditions under which linear trimers and tetramers can be obtained at a high level. The yield of linear phosphonitrile halide to cyclic phosphonitrile halide is increased by using a stoichiometric or higher stoichiometric amount of phosphorus halide, which is the preferred method. In such a preferred method, the selected Lewis acid is from 0.1 to 1 mole, preferably from 0.3 to 0.6 mole, per mole of phosphorus pentahalide.

Representative chlorinated aliphatic or aromatic hydrocarbons which can be used in the present invention and which are inert solvents are sym-tetrachloroethane, monochlorobenzene, o-dichlorobenzene and 1,2,4- Trichlorobenzene. The amount of chlorinated hydrocarbon used as the solvent is not critical if the solid reactants, i.e., phosphorus pentahalide and ammonium halide are used in an amount sufficient to dissolve at least a portion thereof. It is. Of course, if a significant portion of the solid reactant is dissolved, the reaction rate is substantially improved. However, the use of large amounts of solvent is not recommended because it is then necessary to remove the solvent from the reaction product. The method of recovering the desired modified phosphonitrile halide polymer composition is not critical.

If a solid substance is present in the reaction mixture, it can be removed by a conventional method, for example, hot filtration, decantation, centrifugation and the like. Volatile substances, eg, solvents, can be removed by conventional methods, eg, distillation. A preferred method of recovering the catalyst is to remove the reaction solvent and add a solvent that dissolves only the most preferred compounds, for example, dichloromethane. The other compounds can then be filtered off. The catalyst of the present invention can be conveniently stored in a solvent, preferably under a blanket of nitrogen. Accordingly, the present invention also includes a catalyst composition containing the catalyst of the present invention. Other parts of the composition can include certain non-reactive materials, solvents, carriers, and supports used in the manufacture of the catalyst. In the above formula (1), a compound in which n is greater than 0 or 6 may be present. Preferably, the amount of such compounds is kept to a minimum. The concentration of the catalyst in the composition can range from 1 to 50% by weight. Preferably 5 to 20% by weight,
This facilitates the use of the catalyst in the polymerization process.

The catalyst of the present invention is useful for the polymerization of organosiloxanes. Accordingly, the present invention provides the use of a phosphonitrile halide represented by the general formula (1) as defined above in a method for polymerizing organosiloxanes. The catalyst is particularly useful as a condensation catalyst,
Also suitable as a rearrangement catalyst. Thus, the catalyst has the general formula: R ¹ _a SiO _{(4-a) / 2} (2) wherein R ¹ is a hydrogen atom, a hydrocarbon group having 1 to 18 carbon atoms,
A substituted hydrocarbon group having from 18 to 18 or a hydrocarbonoxy group having up to 18 carbon atoms, a having an average value of from 1.8 to 2.2). Useful way to do it.

The R ¹ substituent may be an alkyl group such as methyl, ethyl, propyl, isobutyl, hexyl, dodecyl or octadecyl; an alkenyl group such as vinyl,
Allyl, butenyl, hexenyl or decenyl; alkynyl group such as propargyl; aryl group such as phenyl; aralkyl group such as benzyl; alkaryl group such as tolyl or xylyl; alkoxy group such as methoxy, ethoxy or butoxy; Eg phenoxy; eg trifluoropropyl,
It can be a substituent such as chloropropyl or chlorophenyl. Preferably, at least 80% of all R ¹ groups are alkyl or aryl groups, more preferably methyl groups. Most preferably, substantially all R ¹ groups are alkyl or aryl groups, especially methyl groups. The organopolysiloxanes preferably have a value of 2 for all units except the terminal block unit.

The siloxanes of the general _{^{formula: R 2 [R 1 2 SiO}} ] p SiR 1 2 R 2 (3) ( wherein, R ¹ is the same as defined above, R ² is a R ¹ group or a hydroxyl group And p is an integer). However, it is also possible for units in which a is 0 or 1 to be present in small amounts. Polymers having such units in the chain appear to have a small amount of branching. R ² is preferably a hydroxyl group or an alkyl or aryl group, for example methyl or phenyl.
The viscosity of the organopolysiloxane produced by the method using the catalyst of the present invention ranges from 1,000 to several million mm ² / s, depending on the raw materials and reaction conditions used in the method.

Suitable organosiloxanes used as reagents in the polymerization process in which the catalyst of the present invention is used are polydiorganosiloxanes having terminal hydroxydiorganosiloxane units, such as hydroxyldimethylsiloxane endblocked polydimethylsiloxane, hydroxyldimethylsiloxane It includes endblocked polydimethylpolymethylphenylsiloxane copolymers, triorganosiloxane endblocked polydimethylsiloxanes, such as trimethylsiloxane endblocked polydimethylsiloxane, and cyclic polydiorganosiloxanes, such as polydimethylcyclosiloxane.

The catalyst of the present invention is used in an amount of 1 to 500 based on the total weight of the organosiloxane used as a reagent in the polymerization.
It can be used at a concentration of ppm weight. Preferably 5
150 ppm weight, most preferably 5-50 ppm weight is used. The amount of catalyst used in the process of the present invention can be reduced if the temperature at which the organosiloxane compound and the catalyst are contacted is increased. The method of the present invention can be conveniently performed at room temperature. The temperature can be as high as 250 ° C. However, the temperature range is 20-15
0 ° C is preferred, and 50 to 120 ° C is most preferred.

The catalyst according to the invention can be neutralized at the end of the polymerization reaction, in order to stabilize the reaction product, for example with regard to its viscosity. Neutralization can be performed at any stage of the polymerization process, for example, immediately after the organopolysiloxane has reached the desired viscosity. The neutralizing agent of the catalyst is an alkaline substance, preferably a weakly alkaline substance. Examples of suitable neutralizing agents are diethylamine, propylamine, ammonia and hexamethyldisilazane.

[0023]

The present invention and its usefulness will be described below with reference to examples. Unless otherwise specified, parts and% mean parts by weight and% by weight, respectively. Example 1 ₂ parts of NH ₄ Cl, ₅ parts of PCl ₅ and 1 part of AlCl ₃ were mixed together, and stirred at 180 ° C. for 3 hours using 1,1,2,2-tetrachloroethane as a solvent under a nitrogen blanket. . A white solid was obtained, which dissolved in dichloromethane,
It was not dissolved in diethyl ether. The reaction product has the following average formula: _{[PCl 3 = N-PCl 2} = N-PCl 3] + [AlCl 4] - _{That, [Cl (PCl 2 = N} ) 2 -PCl 3] + [AlCl 4] -

Example 2 0.12 mol of PCl ₅ , 0.08 mol of NH ₄ Cl and Sb
0.04 mol of Cl ₅ was reacted at a reflux temperature of 147 ° C. for 3.5 hours in 60 ml of sym-tetrachloroethane. After the reaction, the solution was filtered to remove insoluble compounds, and then the solvent was removed under reduced pressure. A light yellow liquid was obtained, which crystallized on cooling. The resulting catalyst was analyzed by NMR (nuclear magnetic resonance) spectroscopy. This _{compound, [PCl 3 = N-PCl} 2 = N-PCl 3] + [SbC
l _6] ^- and _{[PCl 3 = N- (PCl 2} = N) 2 -PCl 3] + [Sb
Cl _6] ^- a mixture of 50/50, _{i.e., [Cl- (PCl 2 = N} ) 2 -PCl 3] + [SbC
l _6] ^- and _{[Cl- (PCl 2 = N)} 3 -PCl 3] + [SbCl 6] -
I found to be a mixture of 50/50, and, [PCl _6] ^- anion was observed.

Example 3 Example 2 except that SbCl ₃ was used instead of SbCl _5.
Method was repeated. The resulting _{catalyst, [PCl 3 = N-PCl} 2 = N-PCl 3] + [SbC
l _4] ^- and _{[PCl 3 = N- (PCl 2} = N) 2 -PCl 3] + [Sb
Cl _4] ^- a mixture of 50/50, _{i.e., [Cl- (PCl 2 = N} ) 2 -PCl 3] + [SbC
l _4] ^- and _{[Cl- (PCl 2 = N)} 3 -PCl 3] + [SbCl 4] -
Was a 50/50 mixture .

Example 4 After 3 hours, [PCl ₃ = NP] insoluble in dichloromethane
^{_{Cl 3] + [SbCl 6]}} - except that was separated and subjected to the method of Example 2. Holding the part (A), by refluxing the remaining sym- in tetrachloroethane _{formula: [PCl 3 = N- (PCl} 2 = N) 2 -PCl 3] + [SbCl 6] - That, [Cl @ - A pure compound (B) of (PCl ₂ = N) ₃ -PCl ₃ ] ⁺ [SbCl ₆ ] ⁻ was obtained.

Example 5 The procedure of Example 2 was followed, except that the reaction was continued for 8 hours. The resulting catalyst mixture _{[PCl 3 = N-PCl 2} = N-PCl 3] + [SbC
l _6] ^- 35%, and _{[PCl 3 = N- (PCl 2} = N) 2 -PCl 3] + [Sb
Cl _6] ^- 65%, _{i.e., [Cl- (PCl 2 = N} ) 2 -PCl 3] + [SbC
l _6] ^- 35%, and _{[Cl- (PCl 2 = N)} 3 -PCl 3] + [SbCl 6] -
65% .

Example 6 150 ppm of the catalyst of Example 1 are added to 1500 g of dimethylsiloxanol endblocked polydimethylsiloxane having a viscosity of 100 mm ² / s and the mixture is added at room temperature (18 ° C.) under reduced pressure of 20 mbar at room temperature (18 ° C.). After stirring for a minute, a very high viscosity polydimethylsiloxane was obtained.

[0029] The catalyst of Example 7 Examples 2 and 3 used in the polymerization of the hydroxyl endblocked polydimethylsiloxanes, PCl ₅ 0.
The reaction of 4 moles with 2 moles NH ₄ Cl gives [PCl ₃ = N
_{-PCl 2 = N-PCl 3]} + [PCl 6] - 75%, and _{[PCl 3 = N- (PCl 2} = N) 2 -PCl 3]
⁺ [PCl _6] ^- compared to 25% of the prior art catalyst obtained as a mixture. Three batches of 1500 g of dimethylsiloxanol endblocked polydimethylsiloxane having a viscosity of 100 mm ² / s at 25 ° C. were dried under reduced pressure for 10 minutes to remove all traces of water. Catalyst 1 of Example 2
2 ppm, 12 ppm of the catalyst of Example 3 and 24 ppm of the prior art catalyst, respectively, were added to the first, second and third batches of polydimethylsiloxane under stirring. The first batch had a viscosity of 200,000 mm ² / s after 23 minutes and the first 20 minutes were the induction phase. The second batch had an induction period of 18 minutes and had a viscosity of 200,000 mm ² / s after 21 minutes, whereas the third batch had an induction period of 30 minutes and was 35 minutes later. However, the viscosity did not become 200,000 mm ² / s.

Example 8 This example demonstrates the effect of improving the thermal stability of a polymer produced using the catalyst of the present invention neutralized with amines. The results were compared with the stability of the polymer produced using the classical polymerization catalyst KOH neutralized with CO ₂ . Four batches of polydimethylsiloxanes were produced.
Batches 1 and 2 used 35 ppm of the catalyst prepared in Example 2 at room temperature, and batches 3 and 4 used KOH as the catalyst. Batches 1 and 2 are 41000 and 140, respectively.
After reaching a viscosity of 00 mm ² / s, it was neutralized with dimethylamine. Batches 3 and 4 are 40800 and 1420 respectively
After the viscosity reached 0 mm ² / s, it was neutralized with CO ₂ . All batches were then stored at 160 ° C. for up to 122 hours and the viscosity was measured. As is evident from Table 1, the viscosities of batches 1 and 2 were much more stable than those of batches 3 and 4.

[0031]

[Table 1] Table 1 Viscosity (mm ² / s) Time Batch 1 Batch 2 Batch 3 Batch 4 0 41,000 14,000 40,800 14,200 22 51,500-80,000 25,500 29.5--99,000 30,700 45 51,500-300,000 73,500 70-20,000 500,000 122,000 122 63,500 − − −

Example 9 40 kg of dimethylsilanol endblocked polydimethylsiloxane were mixed with 50 ppm of the catalyst of Example 2 and the mixture was reacted at 80 ° C. for 5 minutes, with 60 pp of diethylamine being added.
m was added to neutralize the catalyst. A viscosity of 300,000 mm ² / s was obtained.

Example 10 Part A of Example 4 was tested as a condensation catalyst by mixing it with dimethylsilanol endblocked polydimethylsiloxane, but showed no catalytic activity when the mixture was heated.

Example 11 Part B of Example 4 and the catalyst of Example 5 were mixed at a concentration of 12 ppm each with 40 g of dimethylsilanol endblocked polydimethylsiloxane and the mixture was reacted at a pressure of 20 mbar and 50 ° C. The reaction proceeds faster with the catalyst of Example 5 and has the formula: [PCl ₃ = N-PCl ₂ = N-PCl
_3] ⁺ [SbCl _6] ^- presence of compounds were shown to improve the catalytic activity.

Example 12 40 g of octamethylcyclotetrasiloxane was used in Example 5.
Was added to the flask along with 120 ppm of the catalyst. At atmospheric pressure,
After reacting at 140 ° C. for 4 hours, about 5
0% polymerized to long chain polydimethylsiloxane, indicating that the catalyst of the present invention was an active rearrangement catalyst.

────────────────────────────────────────────────── ─── of the front page continued (73) patent owner 592015259 PARC INDUSTRIEL, 7180 SENEFFE, BELGIU M (56) reference Patent Sho 49-52300 (JP, a) (58 ) investigated the field (Int.Cl. ⁷ , DB name) C08G 77/08

Claims (9)

(57) [Claims] 1. The following general formula: [X (PX ₂ = N) _n PX ₃ ] ⁺ [MX _{(v-t + 1)} R _t ] ^- (where X represents a halogen atom, and M represents Al,
An element selected from the group consisting of B, Be, Mg, Sb and Si , R is an alkyl group having up to 12 carbon atoms, n has a value of 1 to 6, and v is The valence of M
And t is 0 to v-1. A) a phosphonitrile halide catalyst used for the polymerization of an organosiloxane. 2. The catalyst according to claim 1, wherein in the general formula, X is a chlorine atom, and n has a value of 2-4. 3. The catalyst according to claim 1, wherein the value of t in the general formula is 0. 4. In the above general formula, M is M and [X
The catalyst according to any one of claims 1 to 3, wherein the catalyst is selected from those having the largest difference in electronegativity on a Pauling scale with a phosphorus atom of (PX ₂ = N) _n PX ₃ ] ⁺ . 5. A method for producing a phosphonitrile halide catalyst, comprising reacting a Lewis acid in the reaction between phosphorus pentahalide and ammonium halide. 6. The method according to claim 5, wherein the reaction is carried out in the presence of a chlorinated aliphatic or aromatic hydrocarbon. 7. The chlorinated hydrocarbon is tetrachloroethane, the reaction is carried out at 100-220 ° C., and the reactant is 2-
7. The method of claim 6, wherein the contact is for 10 hours. 8. A catalyst composition comprising the phosphonitrile halide catalyst according to claim 1, and one or more solvents, carriers or supports of the catalyst. 9. The catalyst composition according to claim 8, wherein the composition contains 5 to 20% by weight of a catalyst and 80 to 95% by weight of dichloromethane as a solvent .