JPH0521940B2 - - Google Patents

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION This invention relates to alkoxy-functional one-component RTV silicone rubber compositions, and more particularly to alkoxy-functional one-component RTV silicone rubber compositions in which cure accelerators are formed in situ within the composition. One-part RTV silicone rubber compositions have been known for some time. The initial composition is acyloxy functional, ie the crosslinking agent is acyloxy functional. Compositions of this type are packaged in a one-component container in a substantially anhydrous state. When the composition is desired to cure, the packaging is unsealed. The composition cures into a silicone elastomer when exposed to moisture in the air. Recently, alkoxy-functional one-part RTV silicone rubber compositions have been developed. That is, the crosslinking agent is an alkoxy-functional silane such as methyltrimethoxysilane. Examples of such commercially available compositions are described in BEERS US Pat. No. 4,100,129. Compositions of this type consist of a silanol-terminated diorganopolysiloxane polymer, a trialkoxysilane crosslinker, a titanium chelate catalyst as a condensation catalyst, fillers and various other additives. Although the compositions of the above patents are commercially available and have a shelf life of one year or more and a practical cure rate, there are still problems with these compositions. It has been found that these compositions in some batches are so affected that the storage stability decreases rapidly after one or two months of storage. In fact, it has been found that in most cases the shelf life of such compositions is affected even after two weeks of storage. Moreover, the curing speed of some batches of the above compositions is practically unacceptable. Various improvements have been made to the above compositions which have reduced these obstacles to some extent, but have not completely eliminated them. Improved commercially available alkoxy-functional one-component formulation
RTV silicone rubber compositions are found in US Patent Application No. 277,524 to WHITE et al. As hypothesized, unbound hydroxyl groups in the RTV composition may cause decomposition of the alkoxy groups on the terminal silicon atoms of the diorganopolysiloxane-based polymer. Furthermore, it is speculated that such decomposition of the alkoxy groups results in a significant reduction in the curing rate and storage stability of the RTV composition during storage. Thus, improved RTV alkoxy functional one-component RTV silicone rubber compositions, i.e., improved storage stability and curing by using certain silane scavengers with certain functional groups in the composition. Compositions with velocity are disclosed in US Patent Application No. 277,524 to WHITE et al., supra. This silane scavenger reacts with unbound hydroxyl groups in the RTV mixture to bind them and
They serve to prevent decomposition of the terminal alkoxy groups on the base diorganopolysiloxane polymer. The shelf life and curing rate of the composition is therefore maintained even after long-term storage. Satisfactory commercially available
The shelf life of RTV silicone rubber compositions should be such that they have a tack free time of 120 minutes or more after storage for 6 to 12 months after manufacture. More preferred compositions are alkoxy-functional one-part compositions that have a tack-free time of 60 minutes or less after being stored anhydrous in a container for a period of one year or more.
RTV silicone rubber composition. Such compositions had been developed as shown in US Patent Application No. 277,524 to WHITE et al. WHITE
et al., US Patent Application No. 277,524, indicates that the functional group of the silane scavenger can be an amino group. This patent application also indicates that curing accelerators selected from amines and guanidines may optionally be present. It is also important to look at U.S. Patent Application No. 462,949 to MITCHELL, which provides certain types of alkoxy-functional one-component RTV silicone rubber compositions similar to those described in U.S. Patent Application No. 277,524 to WHITE et al. discloses the use of an alkoxy-functional amine-functional siloxane scavenger or crosslinker-cum-scavenger. WHITE et al., U.S. Pat. No. 277,524, discloses silanol-terminated diorganopolysiloxane polymers
part, preferably 0.1 to 5 parts of curing accelerator.
It is indicated that it may be included in a concentration of 0.1 to 1 part, more preferably 0.3 to 1 part. Furthermore, it has also been shown that at this concentration of accelerator, the composition has a tack-free time of less than 60 minutes after accelerated aging of the uncured composition. This patent application discloses that the crosslinking agent and scavenger or scavenger is used in excess of up to 3%, based on the base polymer, over the amount required to end-cap the base silanol-terminated diorganoborisiloxane polymer. It is also stated that it is preferable that the WHITE
No. 277,524, for every 100 parts by weight of a silanol-terminated diorganopolysiloxane polymer base, up to 0.5 parts of a crosslinker and scavenger are added for the purpose of endcapping the base polymer. It is desirable to add up to an additional 3 parts by weight of a crosslinking agent and scavenger for scavenging purposes, and generally from 0.1 to 5 parts by weight.
%, more preferably from 0.3 to 1 part of an amine curing accelerator. Here, surprisingly, instead of adding the crosslinker/scavenger and accelerator separately, if the crosslinker/scavenger is amine-functional, that is all that is needed, and the primary or secondary amine is the accelerator. was found to be liberated in sufficient quantities to act as a One of the objects of the present invention is to demonstrate a method for forming amine cure accelerators in situ in alkoxy-functional one-part RTV silicone rubber compositions. Another object of the present invention is to demonstrate a method for producing amine-functional cure accelerators in situ by reacting an amine-functional crosslinker and scavenger with a silanol-terminated diorganopolysiloxane polymer. be. Yet another object of the present invention is to provide an alkoxy-functional one-component solution by reacting a primary and secondary amine-functional crosslinker and scavenger with a silanol-terminated diorganopolysiloxane polymer.
To demonstrate a method for producing amine-functional cure accelerators in situ in RTV silicone rubber compositions. Alkoxy-functional monoliquid by in situ formation of an amine-functional cure accelerator resulting in a final cured composition having a tack-free time of 60 minutes or less after a storage period of one year or more.
It is another object of the present invention to present a method of making RTV silicone rubber compositions. These and other objects of the present invention are achieved by the invention set forth below. Summary of the invention In accordance with the above purpose, (A) formula 100 parts by weight of a silanol-terminated polydiorganosiloxane consisting essentially of chemically bonded units of (B) for the hydroxy functional group, of the formula at least 4 parts of a silane scavenger having the formula (C) (D) an effective amount of a condensation catalyst, where R is selected from C _1-13 monovalent substituted or unsubstituted hydrocarbon groups, and R ¹ is alkyl, alkyl ether, alkyl ester; , a C _1-8 aliphatic organic group selected from the group consisting of an alkyl ketone and an alkyl cyano group, or a C _7-13 aralkyl group, R ² is
C _1-13 monovalent substituted or unsubstituted hydrocarbon group, X is an amino hydrolyzable leaving group, a is an integer of 1 to 3, b is an integer of 0 or 1, the sum of a + b is 1 to 3) The present invention provides a method of making a substantially acid-free one-component silicone rubber composition, which forms a cure accelerator immediately upon mixing the components, comprising mixing the ingredients. The compounds of formula (1) are crosslinkers and scavengers where X is a primary or secondary amine, more preferably a secondary amine. When the secondary amine is liberated when the crosslinking agent and scavenger of formula (1) reacts with the silanol-terminated diorganopolysiloxane polymer to cap the ends, it acts as an end-capping catalyst and also acts as a curing accelerator. . Free primary amines also act in a similar manner. Additionally, extra crosslinking agent of formula (2) may optionally be added to the composition in order to terminate the silanol-terminated diorganopolysiloxane polymer base as much as possible with terminal alkoxy groups. Crosslinking agents and scavengers, whether silanes or siloxanes, release the primary or secondary amines mentioned above when they react with the silanol groups on the diorganopolysiloxane polymer, crosslinking the silanol-terminated diorganopolysiloxane polymer base. The tack-free time of the composition after storage for a period of one year or more is preferably
It also acts as a curing accelerator to maintain the cure time under 30 minutes. A preferred crosslinker is methyltrimethoxysilane and a preferred silane scavenger is methyldimethoxy(di-N-hexylamino)silane. Additionally, in order for the composition to cure and obtain the properties of RTV silicone rubber compositions (RTV refers to room temperature vulcanizability in this application), the composition preferably contains a condensation catalyst, such as dibutyltin dilaurate or dibutyltin diacetate. It is necessary to contain a tin condensation catalyst such as DESCRIPTION OF PREFERRED EMBODIMENTS As described above, for producing a commercially available product, one that exhibits storage stability of about 6 to 12 months and has a tack-free time of 120 minutes or less after its storage period. For every 100 parts of silanol-terminated diorganopolysiloxane polymer, there should be at least about 4 parts of crosslinker and scavenger present. Preferred storage-stable alkoxy-functional one-part RTV compositions include storage-stable compositions that can be stored for a period of one year or more and have a tack-free time of 60 minutes or less after storage for that period. It is. To achieve such storage stability, silanol-terminated diorganopolysiloxane polymers
It is necessary to have about 5 to 7 parts of crosslinker and scavenger per 100 parts. It is also possible to use more than 7 parts of crosslinker and scavenger, but no beneficial results are obtained. It must be noted that the minimum value of 4 parts is the lowest limit determined by experimentation with the crosslinking agents of the Examples. This minimum value varies to some extent depending on the type of amine-functional crosslinker and scavenger. Therefore, reference is made in the specification and examples to at least about 4 parts crosslinker and scavenger in the composition.
Di-N-hexylamine is a secondary amine and is one of the more effective and preferred curing accelerators. It should also be said that di-N-hexylamine liberated as an in situ curing accelerator in the examples is a more effective curing accelerator compared to primary amines. The results of the examples thus demonstrate that the crosslinker produces an alkoxy-functional RTV silicone rubber composition in which the crosslinker forms an in-situ cure accelerator for a composition with suitable storage stability and tack-free time. reflects the lowest valid range. Other amines liberated from the crosslinker/scavenger may be slightly more effective and therefore "at least about 4 parts" should be added to the accelerator to provide a composition that cures at a suitable rate. It is used as the minimum amount of crosslinker and scavenger needed in the composition for in-situ manufacturing. A minimum amount of about 4 parts of crosslinker and scavenger is WHITE
This effect is not cumulative, as it cannot be predicted from the use of individual additives in the composition, as shown on page 13 of U.S. Pat. That application discloses that the curing accelerator is not formed in situ, but is a separate compound that is subsequently added to the composition during mixing or manufacturing of the composition. 10 of its applications
The page indicates that an excess of up to 3% by weight of scavenger may be used in the composition. In the experiments reported in the Examples of this application,
For every 100 parts of silanol-terminated diorganopolysiloxane polymer, at least 4 parts of crosslinker and scavenger are utilized to obtain a commercially viable composition. Only 0.33 parts of crosslinker and scavenger are required to completely chain terminate the silanol-terminated diorganopolysiloxane polymer. This is a theoretical value. The above amount of crosslinker and scavenger liberates about 0.12 parts of di-N-hexylamine as a cure accelerator. Thus, according to the disclosure of U.S. Pat. A portion of crosslinker and scavenger is added. However, as the experimental results of the Examples show, in order to produce commercially practical RTV compositions, that is, compositions with commercially practical storage stability and tack-free time, it is necessary to Both require about 4 parts of a crosslinking agent and scavenger. Therefore, the above discussion points out that if the curing accelerator is formed in situ, the effect is
It is not cumulative, as expected from the disclosure of US Patent Application No. 277,524 to WHITE et al., but is to be determined in an experimental manner. Nowhere in WHITE et al., US Pat. Similar to other patent applications, the above patent application:
The curing accelerator is a separate compound and is another ingredient added to the composition during the mixing operation. One of the advantages, and a fundamental advantage, of the compositions of the present invention is that they are more easily formed in a continuous process, i.e. one component has to be added rather than two separate components; No. 437,895 to CHUNG et al.
The preparation of the composition is facilitated by continuously mixing the components in a devolatilizing extruder such as that shown in No. This is even the case if another accelerator is added to the composition, even though more crosslinker and scavenger will be used in the composition than is normally used. Thus, a major advantage of the process of the present invention is the ease of manufacturing alkoxy-functional RTV compositions, and more particularly the continuous formation or manufacture of such compositions. Referring to compounds of formula (1), such compounds are well known as shown in US Patent Application No. 277,524 to WHITE et al. This compound is
Somewhat different from the compounds shown in U.S. Patent Application No. 277,524 to WHITE et al., which are not only crosslinkers and scavengers, but can also have an alkoxy group on the silicon atom. Thus, from this crosslinking agent, a diorganopolysiloxane polymer base having only one alkoxy group on the terminal silicon atom and one or two amino groups on the terminal silicon atom of the polymer chain is formed. It is possible to do so. Such compositions are included within the scope of the present invention and are cured in accordance with the present disclosure. Formation of the above polymeric base is also shown in LUCAS US Patent Application No. 449,105. Compounds of formula (1) are more particularly described in US Pat. LUCAS
No. 449,105. Sideways
Whether using the crosslinking agent and scavenger of WHITE et al., U.S. Patent Application No. 277,524, or that of LUCAS, U.S. Patent Application No. 449,105, cure accelerators can be applied in situ in accordance with the present disclosure. 1, 2 or 3 terminal silicon atoms to form a composition with desirable storage stability and cure rate.
An end-stopped polymer having 5 alkoxy groups is formed. When the crosslinker and scavenger of formula (1) chains terminates the silanol-terminated diorganopolysiloxane polymer, the amines (which may be primary or secondary) that are liberated are described in U.S. Patent Application No. WHITE et al.
It must be mentioned that it also acts as an end-binding catalyst according to the disclosure of No. 277524. Other end-linked catalysts may be used as disclosed in US Patent Application No. 427,930 to CHUNG et al. It is further stated above that the crosslinking silane of formula (2) ensures maximum chain termination of the silanol-terminated diorganopolysiloxane polymer and that the crosslinking density in the composition is high. It is disclosed that it may be used as an optional crosslinking agent in the composition. Additionally, together with or in place of silane, which is a crosslinker and scavenger of formula (1), [In the formula, R ¹ and R ² are as defined below, and A
is the expression A group consisting of a simple amine (wherein R ¹⁰ and R ¹¹ are independently selected from hydrogen and a C _1-8 monovalent hydrocarbon group), x varies in the range of 0.05 to 2.50, and y
[0.00 to 2.50], w varies from 0.05 to 1.5, and the sum of x+y+w varies from 2.10 to 3.00. The compound of formula (3) differs from the compound of formula (1) in that it is a siloxane, but is also a crosslinker and scavenger. This compound has at least one alkoxy group and has 2 to 20 silicon atoms. The amine functionality in the siloxane of formula (3) is either a simple primary or secondary amine. A more preferred amine-functional siloxane crosslinker and scavenger compound is a compound of the formula: [In the formula, R ¹ and R ² are as defined above, and A is the formula (wherein R ¹⁰ and R ¹¹ are independently selected from hydrogen and C _1-8 monovalent hydrocarbon group), m is 0.15
~2.50, n varies from 0.1 to 1.9, o varies from 0.05 to 2.00, m+n+
The sum of o varies from 2.10 to 3.00. Compounds of formula (4) are preferred crosslinking agents and scavenge siloxanes within the range of compounds of formula (3) having at least three alkoxy groups in the polymer. It is a compound. The compounds also have 2 to 20 silicon atoms in the polymer chain. For the amine functionality, the formula
The compound of formula (4) must have at least the same amount, ie one amino group in the polymer, but the maximum amount is more amino groups than is possible in the compound of formula (3). It may be included during coalescence. These compounds of formula (4) are therefore more preferred crosslinkers and scavengers. For further information regarding the preparation of compounds of formulas (3) and (4) and their use in preparing alkoxy-functional one-part RTV silicone rubber compositions, see MITCHELL, U.S. Patent Application No. 462,949. You can refer to the description. The same compounds disclosed in that patent application are used herein with the additional purpose of adding said amount of crosslinker and scavenger to the composition in order to form a curing accelerator in situ in the composition. It has been revealed. For such compounds, especially those with high molecular weight and few amino groups, significantly higher amounts of such compounds may be incorporated into the composition than is the case for the simpler amines of formula (1), which is a minimum of about 4 parts, as discussed above. It is necessary to use it as a crosslinking agent and scavenger in the process. Compounds of formulas (1), (3) and (4) are described in U.S. Patent Application No. 277,524 to WHITE et al., U.S. Patent Application No. 277,524 to LUCAS
449105 and MITCHELL U.S. Patent Application No.
No. 462,949, supra, and its use as a crosslinking agent and scavenger is fully described in those applications. In order to generate in situ primary and secondary amine cure accelerators that improve the cure rate of the composition, the aforementioned amounts are added so that these components act not only as crosslinkers and scavengers but also as pure scavenger compounds. It can be mixed into the composition. The silanol-terminated diorganopolysiloxane polymer preferably has the formula [wherein R is independently selected from C _1-13 monovalent substituted or unsubstituted hydrocarbon groups (preferably methyl or major amounts of methyl and minor amounts of phenyl, cyanoethyl, trifluoropropyl, vinyl and mixtures thereof); , n is an integer from about 50 to about 2500. Preferably, the polymer has a viscosity in the range of 100 to about 400,000 centipoise, more preferably in the range of about 1.000 to about 250,000 centipoise, measured at about 25°C. n in formula (5) is 500~
A range of 2000 is preferred. Examples of groups included in R in formulas (1), (2), and (5) include aryl groups and halogenated aryl groups such as phenyl, tolyl, chlorophenyl, and naphthyl; aliphatic groups such as cyclohexyl and cyclobutyl; There are cycloaliphatic groups, alkyl and alkenyl groups such as methyl, ethyl, propyl, chloropropyl, vinyl, allyl, trifluoropropyl, and cyanoalkyl groups such as cyanoethyl, cyanopropyl, cyanobutyl. Examples of groups included in R ¹ preferably include C _1-8 alkyl groups such as methyl, ethyl, propyl, butyl, pentyl; C _7-13 such as benzyl and phenethyl;
Aralkyl group, alkyl ether group such as 2-methoxyethyl, alkyl ester group such as 2-acetoxyethyl, alkyl ketone group such as 1-butan-3-onyl, and alkylcyano group such as 2-cyanoethyl. be. The groups contained in R ² are the same as the groups contained in R. The groups R, R ¹ and R ² have the above formulas, that is, formulas (1), (2),
It may be any of the groups specified above as defined in (3), (4) and (5) and may be the same or different in the compound or polymer. The polyalkoxy-terminated polydiorganopolysiloxane produced by the reaction of the silanol-terminated diorganopolysiloxane polymer of formula (5) with the crosslinker and scavenger of formula (1) preferably has the following formula: be. (wherein R, R ¹ and R ² are as defined above, X is a hydrolyzable amino leaving group, e is an integer of 0 to 2, b is an integer of 0 or 1, b+e is 0 to 2, n is about 50 to approx.
2500) Such preferred polyalkoxy-terminated diorganopolysiloxanes of formula (6) are desirably formed in the RTV compositions of the present application and can be mixed with the other components of the compositions in a variety of ways. and can form various types of mixtures. A preferred example of such a mixture is (i)(a) formula 100 parts of a silanol-terminated polydiorganosiloxane consisting essentially of chemically bonded units of (b) for the hydroxy functional group, of the formula at least 4 parts of silane scavenger of formula (c) (d) an effective amount of a condensation catalyst; and (ii) (a) a mixture of 0 to 10 parts of a crosslinking silane of formula 100 parts of a polyalkoxy-terminated polydiorganosiloxane of formula (b) 0 to 10 parts of a crosslinking silane; (c) an effective amount of a condensation catalyst; (However, R, R ¹ , R ² and X are defined as
a is an integer of 1 to 3, b is an integer of 0 or 1, a+b
is 1 to 3, e is an integer of 0 to 2, b+e is 0 to 2,
n is an integer from about 50 to 2500).
It can also be produced using a crosslinking agent/scavenger of formulas (3) and (4). In either case, a cure accelerator is formed which acts to provide an RTV composition with suitable storage stability and cure rate. A preferred crosslinking agent of formula (2) in the present invention is methyltrimethoxysilane. Preferably R, R ¹ and R ² are methyl. Additionally, if the composition is crosslinked to a certain density,
If silicone rubber compositions are to be cured to have the properties that they normally have, it is necessary to have a condensation catalyst. A preferred condensation catalyst is a tin condensation catalyst. An effective amount of condensation catalyst that can be used to facilitate curing of RTV compositions in embodiments of the invention is, for example, based on the weight of 100 parts of silanol-terminated polydiorganosiloxane of formula (1).
It is 0.001 to 1 part. Examples of tin compounds include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dimethoxide, carbomethoxyphenyltin trisuberate, tin octoate, isobutyltin triceroate, dimethyltin dibutyrate, dimethyltin di-neodeconoate, triethyltin tartrate, These include dibutyltin dibenzoate, tin oleate, tin naphthenate, butyltin tri-2-ethylhexoate, and tin butyrate. Preferred condensation catalysts are tin compounds, with dibutyltin diacetate being particularly preferred. Titanium compounds that can be used include, for example, 1,3-propanedioxytitanium bis(ethylacetoacetate), 1,3-propanedioxytitanium bis(acetylacetonate), diisopropoxytitanium bis(acetylacetonate), titanium naphthenate, titanium Tetrabutyl acid, tetra-titanate
2-ethylhexyl, tetraphenyl titanate,
Tetraoctadecyl titanate, ethyltriethanolamine titanate. Additionally, beta-dicarbonyl titanium compounds such as those shown in WEYENBERG U.S. Pat. No. 3,334,067,
It can be used as a condensation catalyst in the present invention. For example, zirconium compounds such as zirconium octoate can also be used. Furthermore, examples of metal condensation catalysts include, for example, 2-
Lead ethyl octoate, iron 2-ethylhexanoate,
These include cobalt 2-ethylhexanoate, manganese 2-ethylhexanoate, zinc 2-ethylhexanoate, antimony octoate, bismuth naphthenate, zinc naphthenate, and zinc stearate. Examples of non-metallic condensation catalysts are hexylammonium acetate and benzyltrimethylammonium acetate. Various fillers and pigments can be incorporated into the silanol- or alkoxy-terminated organopolysiloxanes, such as titanium dioxide, zirconium silicate, silica aerogels, iron oxides, diatomaceous earth, formulated silica, carbon black, precipitated silica, glass. Fibers, polyvinyl chloride, quartz powder, calcium carbonate, etc. The amount of filler used can obviously vary within a wide range depending on its intended use. For example, in certain sealant applications, the curable compositions of the present invention can be used without fillers. In other applications, such as using the cured composition to make a binder, 700 parts or more of filler can be used per 100 parts of organopolysiloxane on a weight basis. In such applications, the filler consists of a large amount of filler, such as quartz powder, polyvinyl chloride, or mixtures thereof, and preferably has an average particle size in the range of about 1 to 10 microns. The compositions of the invention can also be used as architectural sealants and caulking compounds. Therefore, the exact amount of filler will depend on factors such as the application of the organopolysiloxane composition and the type of filler used (ie, the density of the filler and its particle size). Preferably, 10 to 300 parts of filler are used per 100 parts of silanol-terminated organopolysiloxane, including up to about 35 parts of reinforcing filler, such as a framed silica filler. As used hereinafter, the one-component polyalkoxy-terminated organopolysiloxane RTV of the present invention
used for. The term "stable" refers to moisture-curable mixtures that undergo little change unless exposed to atmospheric moisture and that harden to a tack-free elastomer even after long periods of storage. In addition, stable RTV means that the tack-free time exhibited by freshly mixed RTV components under atmospheric pressure conditions extends over a long storage period at ambient conditions or an equivalent period based on accelerated aging at elevated temperatures. Means nearly the same as that exhibited by a mixture of the same components when kept in a moisture-resistant, moisture-free container and then exposed to atmospheric moisture. In connection with defining the elastomer formed by exposing the RTV composition of the present invention to atmospheric moisture,
The expression “substantially no acid generation” means that the pka is 5.5.
or more, preferably 6 or more, particularly preferably 10 or more by-products. In addition to the above ingredients, the composition may also contain other ingredients such as plasticizers, sag control agents, adhesion promoters to provide low modulus. Examples of such additives are BEERS U.S. Patent Application No. 349,537 and
As shown in LUCAS US Patent Application No. 349,538. The compositions can be made in a number of ways, but are most preferably made by mixing the crosslinker and scavenger with the silanol-terminated diorganopolysiloxane polymer in a substantially anhydrous manner, followed by any terminal attachment. Add more catalyst for. However, the reaction mixture is autocatalytic as described above. U.S. Patent Application No. 347895 to CHUNG et al.
Other ingredients, including plasticizers, adhesion promoters, fillers, etc., can be added in subsequent mixing steps or at the point of mixing, as indicated in the above. Additionally, an excess of crosslinker and scavenger may be added in an additional mixing step, as shown in U.S. Patent Application No. 347,895 to CHUNG et al. . The minimum amount of each crosslinker and scavenger should be determined by the experiments shown above. Once formed, the composition is packaged in a moisture-proof package in a substantially anhydrous manner, stored, and marketed as such. If you want to harden the composition,
The package seal is broken and the composition is exposed to atmospheric moisture, thereby curing into a silicone elastomer that is completely cured in 24 to 72 hours.
As previously described, this composition may be made continuously or semi-continuously as shown in U.S. Patent Application No. 347,895 to CHUNG et al., or may be made or mixed in batches if desired. . The following examples are presented for the purpose of illustrating the invention. They are not presented for the purpose of limiting or delimiting the invention. All parts in the examples are by weight. A preferred crosslinking agent and scavenger within formula (1) is methyldimethoxy (di-N-hexylamino).
Silane, Methyldimethoxy(di-N-methylamino)silane, Methyldimethoxyisopropylaminosilane, Methyldimethoxy(di-N-butylamino)silane, Methyldimethoxy(di-N-isobutylamino)silane, Methyldimethoxy(di-N- propylamino)
silane, methyldimethoxy(di-N-vinylamino)silane. Preferred tin condensation catalysts for use in the present invention are dibutyltin diacetate and dibutyltin dilaurate. EXAMPLE A 5 liter three-necked flask equipped with a stirrer, pot thermometer, water reflux condenser with N ₂ inlet, and two 250 ml isobaric addition funnels was purged with dry N ₂ , hexane 2, Et ₃ N 2 Add moles (280 parts). After stirring and purging with _N2 , add to the addition funnel.
Add 1.00 mol (140 parts) of CH ₃ Si (OCH ₃ ) ₂ Cl.
In the second addition funnel, add di-N-hexylamine.
Add 1.25 moles (231.8 parts). _CH3Si ( _OCH3 ) _2Cl while stirring under an atmosphere of _N2 at room temperature.
Add rapidly to the pot mixture. Di-N-hexylamine is added dropwise to the rapidly stirred pot mixture over a period of 2 hours. There is a slight fever, raising the temperature of the pot to 22°C to 35°C. A large amount of solid white triethylamine hydrochloride is produced during the reaction process. After stirring for 15 hours at room temperature, the solids are removed by vacuum filtration and the liquid volatiles are removed by rotary flash evaporation under reduced pressure. Vacuum filtration yields the desired product, methyldimethoxy(di-N-hexylamino)silane, which has a bp of 113-115°C/5 mmHg and is 92% pure by chromatographic analysis. The _CH3 -Si( _OCH3 ) ₂ -N(hexyl) ₂ is then mixed with the polymer, filler and Sn ⁺⁴ catalyst using a Semkit® mixer under anhydrous conditions. Two catalyst addition steps are performed as follows. In the first step, consisting of a 15 minute mixing time at room temperature, 85 parts by weight of a silanol-terminated dimethylpolysiloxane polymer having a viscosity of 3000 centipoise at 25°C, 15 parts by weight of an octamethylcyclotetrasiloxane-treated humidica filler, and Mix 2 to 6 parts of methyldimethoxydihexylaminosilane as shown in the table below. This mixture was taken and added 0.23 parts dibutyltin diacetate and
With silanol content ranging from 500 to 1500 ppm
Mix 21 parts by weight of a trimethylsiloxy-terminated dimethylpolysiloxane polymer having a viscosity of 100 centipoise at 25°C. After mixing, the RTV composition is packed into aluminum sealed tubes and stored for 24 hours at room temperature, 24 hours at 100°C, and 48 hours at 100°C before being exposed to a curing environment at room temperature, 50% RH. The rate of cure and degree of cure are determined by tack free time (TFT) and 24 hour durometer measurements. Acceptable curing is TFT
is defined by a 30 minute, 24 hour durometer 28. The results are shown in the table.

【table】

[Table] Examples A 5 liter three-necked flask equipped with a stirrer, pot thermometer, water reflux condenser with N ₂ inlet, and two 250 ml isobaric addition funnels was purged with dry N ₂ and 2 liters of hexane and 2 mol ( 280ml)
Add _Et3N . After stirring and purging with _N2 , add 1.00 moles of _CH3Si ( _OCH3 ) _2Cl (140
section). In a second addition funnel, charge 1.25 moles (161.6 parts) of di-N-butylamine. CH ₃ Si while stirring at room temperature under N ₂ atmosphere
Rapidly add ( _OCH3 ) _2Cl to the pot mixture. Di-N-butylamine is added dropwise to the rapidly stirred pot mixture over a period of 2 hours. A slight fever was observed, and the pot temperature was increased to 22℃~
Raise to 35°C. A large amount of solid white triethylamine hydrochloride is formed during the course of the reaction. 15 at room temperature
After stirring for an hour, solids are removed by vacuum filtration and liquid volatiles are removed by rotary flash evaporation under reduced pressure. Vacuum filtration yields the desired product, 7
Methyl dimethoxy (di-N
-butylamino)silane is formed. The aminosilane is then mixed with the polymer, filler and tin catalyst using a Semkit® mixer under anhydrous conditions. The catalyst addition step is as follows. To 85 parts of the same silanol-terminated dimethylpolysiloxane polymer as in the example, 15 parts of the treated fumed silica filler as in the example.
2 to 5 parts of aminosilane are added, resulting in a concentration of 2 to 5 parts in the mixture. This mixture is mixed in a first mixing step for 15 minutes at room temperature. At room temperature in a Semkit® mixer
Upon catalyst addition after the 15 minute mixing step, this initial mixture contains 0.23 parts of dibutyltin diacetate and silanol in the range of 500-1500 ppm;
Add trimethylsiloxy-terminated dimethylpolysilane polymer having a viscosity of 100 centipoise at 25°C and mix. Curing data obtained from the above compositions, including accelerated aging and tack free time where applicable, are shown in the table below.

【table】

Claims (1)

[Claims] 1 (a) Formula 100 parts by weight of a silanol-terminated polydiorganosiloxane consisting essentially of chemically bonded units of (b) for the hydroxy functional group, of the formula a silan scavenger having at least about 4
part, (c) Eq. (d) an effective amount of a condensation catalyst, where R is selected from C _1-13 monovalent substituted or unsubstituted hydrocarbon groups, and R ¹ is alkyl, alkyl ether, alkyl ester; , a C _1-8 aliphatic organic group or a C _7-13 alkyl group selected from the group consisting of alkylketones and alkylcyano groups, R ² is a monovalent substituted or unsubstituted C _1-13 hydrocarbon group, and X is amino hydrolyzable leaving group, a is an integer of 1 to 3, b is 0 or 1
, the sum of a+b is from 1 to 3), and is a substantially acid-free, one-component, room-temperature curing agent that forms a curing accelerator immediately upon mixing the ingredients. A method of manufacturing a sulfuric silicone rubber composition. 2. The method according to claim 1, wherein the crosslinking agent is methyltrimethoxysilane. 3. The method according to claim 2, wherein R, R ¹ and R ² are methyl. 4. The method according to claim 3, wherein the condensation catalyst is a tin compound. 5. The method of claim 4, wherein the condensation catalyst is selected from the group consisting of dibutyltin dilaurate and dibutyltin diacetate. 6. The method of claim 1, wherein the silane scavenger is methyldimethoxy(di-N-hexylamino)silane. 7 Silane scavenger is methylmethoxydi-N
-Methylaminosilane Claim 1
The method described in section. 8 Claim 1 in which the silane scavenger is methyldimethoxyisopropylaminosilane
The method described in section. 9. A substantially acid-free, room temperature vulcanizable organopolysiloxane that uses an effective amount of condensation catalyst with a silanol-terminated organopolysiloxane and a polyalkoxysilane crosslinker to form a cure accelerator in situ upon mixing the components. A method of preparing a composition under substantially anhydrous conditions, comprising: a silanol-terminated organopolysiloxane;
100 parts by weight, formula (In the formula, R ¹ is a C _1-8 aliphatic organic group or C _7-13 aralkyl group selected from the group consisting of alkyl, alkyl ether, alkyl ester, alkyl ketone, and alkyl cyano group, and R ² is C _{1- 13} monovalent substituted or unsubstituted hydrocarbon group, X is an amino hydrolyzable leaving group, a is an integer of 1 to 3, b is an integer of 0 or 1, a
+b sum of 1 to 3), which is a polyalkoxysilane which is a scavenger for hydroxy functional groups and a crosslinking agent, and then an effective amount of a condensation catalyst. The method described in paragraph 1. 10. The method according to claim 9, wherein the crosslinking agent is methyltrimethoxysilane. 11. The method of claim 10, wherein 11 R, R ¹ and R ² are methyl. 12. The method according to claim 11, wherein the condensation catalyst is a tin compound. 13. The method of claim 12, wherein the condensation catalyst is selected from the group consisting of dibutyltin dilaurate and dibutyltin diacetate. 14. The method of claim 9, wherein the silane scavenger is methyldimethoxy(di-N-hexylamino)silane. 15 Silane scavenger is methyl methoxy di-
10. The method of claim 9, wherein N-methylaminosilane is used. 16. The method of claim 10, wherein the silane scavenger is methyltrimethoxyisopropylaminosilane. 17 By reacting a silanol-terminated polydiorganosiloxane with a silane scavenger, the formula After forming 100 parts of a polyalkoxy-terminated polydiorganosiloxane, 0 to 10 parts of a crosslinking silane and an effective amount of a condensation catalyst are added (where R, R ¹ ,
R ² and b are as defined above, and e is 0
An integer of ~2, the sum of b+e is 0~2, n is about 50~
3. The method of claim 1, wherein: