JPH0455225B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a one-component alkoxy-functional room temperature curable (hereinafter referred to as RTV) silicone rubber composition, and more particularly, the present invention relates to a method for producing a one-component alkoxy-functional room temperature curable (hereinafter referred to as RTV) silicone rubber composition.
The present invention relates to a method for producing a one-component alkoxy-functional RTV silicone rubber composition using. One-component alkoxy-functional RTV silicone rubber compositions are disclosed in Beers U.S. Pat.
It is well known as exemplified by No. 4100129. An important innovation in the processing of such compositions is the anhydrous mixing of the ingredients prior to packaging in a twin-screw devolatilizing extruder, as disclosed in U.S. Pat. No. 3,960,802 to Bears et al. It was a method. As pointed out in the above patent, mixing was done more effectively in the devolatilizing extruder. Furthermore, it has been found that lower viscosity blend compositions can be obtained by use of a devolatilizing extruder. The process was an important innovation in the production of alkoxy-functional one-component BTV compositions because it allowed such compositions to be produced continuously at a somewhat lower cost than previous mixing methods. Recently, one-component storage-stable alkoxy-functional RTV silicone rubber compositions have been developed, such as those disclosed in White et al., US Pat. No. 4,395,526. This US patent discloses the initial preparation of polyalkoxy-terminated diorganopolysiloxane polymers. When making this polymer, scavengers are added to tie-up the free alcohol and hydroxy groups, and the uncured polymer mixture is used as fillers, adhesion promoters, condensation catalysts, etc. The first along with other added ingredients like
Used in the production of RTV systems. The innovation disclosed in this patent is to add a scavenger to the polyalkoxy end-capped diorganopolysiloxane polymer following formation of this polymer in order to link any free hydroxy groups that degrade the polymer. be. The production of an uncured composition in which the free hydroxy groups and alcohols in the mixture are linked provides a storage-stable composition. Namely, Bears U.S. Pat. No. 4,100,129 and U.S. Pat.
Although the composition of No. 3960802 was storage stable,
The curing speed after storage for 6 months or more is still not fast enough. Indeed, as pointed out in the above-mentioned U.S. Pat. No. 4,395,526 to White et al.
Such compositions appear to suffer from decreased storage stability after storage for a short period of two weeks. Thus, if a polyalkoxy-terminated diorganopolysiloxane polymer is first formed and a hydroxy group scavenger is used in this composition, as pointed out in White et al., U.S. Pat. No. 4,395,526, It is believed that the storage stability of the composition could be maintained longer and that alkoxy-functional RTV compositions, which traditionally have slow cure rates, would have had even faster cure rates. Other advances have been made in this area. For example, US Pat. No. 4,424,157 to Chung discloses the use of certain cyclic amides as scavengers. Additionally, Bears' US Pat. No. 4,513,115 teaches that by using certain scavengers, particularly those of White et al.'s US Pat. No. 4,395,526, certain additives render the compositions low modulus. The present invention discloses the preparation of storage-stable alkoxy-functional compositions that cure rapidly. Additionally, there is the disclosure of Dziark, US Pat. No. 4,417,042. This patent discloses the use of certain silazane scavengers for the above compositions. Then there is the disclosure of Lucas et al., US Pat. No. 4,483,973. This patent is
Alkoxy-functional one-component RTV systems of White et al., U.S. Pat. No. 4,395,526 and Zudziak, U.S. Pat.
No. 4,513,115 discloses the use of certain adhesion promoters. Further advances are being made in this area. For example, Chiyoung et al.
There is No. 4720531. This patent discloses the use of certain alkoxy-functional silazane as either a composite scavenger and a crosslinking agent. Further, there is the disclosure of European Patent No. 137883 to Chiyoung. This patent discloses the use of certain acidic catalysts and combinations of acidic and amine catalysts as coupling catalysts for the endcapping of polyalkoxy-terminated diorganopolysiloxane polymers. All of these compositions were highly desirable and innovative in the production of storage stable, fast curing, low modulus, one component RTV silicone rubber compositions. I must make one point clear. Most of the compositions of Bears, US Pat. No. 4,100,129 and Bears et al., US Pat. No. 3,960,802 appear to cure even after periods as long as one or two years. However, the handling of this composition has not always been simple, efficient or economical, since its curing rate is substantially affected and drops to an undesirable degree after long-term storage. As well as other U.S. patents, the White et al.
439,552 is a storage-stable composition, i.e., after the composition has been stored.
The objective was to produce a composition that had a cure rate that was not as reduced as that of the compositions of No. 4,100,129 and the compositions of Bears et al., US Pat. No. 3,960,802. Therefore, the alkoxy functionality
The compositions of White et al., U.S. Pat. No. 4,395,526, Zudziak et al., U.S. Pat. This results in a more storage-stable, fast-curing composition. A method for making such compositions includes mixing the silanol-terminated backbone polymer with a crosslinker and an end-coupling catalyst without a scavenger in a first mixing step, and then combining the condensed catalyst mixture with a scavenger in a second mixing step. It was highly desirable to mix them together. For such compositions, more thorough mixing methods, particularly continuous mixing methods, would be desirable. If a continuous mixing method were developed for such compositions, it would result not only in the production of larger quantities of material in a given amount of time, but also in labor savings. One object of the present invention is to provide a continuous mixing process for producing scavenger-containing alkoxy-functional one-component RTV compositions. Another object of the invention is that the mixing is carried out by a devolatilizing extruder, which provides storage stable, rapid curing,
The object of the present invention is to provide an efficient method for producing alkoxy-functional RTV silicone rubber compositions. Yet another object of the present invention is to provide an efficient continuous mixing method. This method is
By first mixing in a static mixer to form an end-capped polyalkoxydiorganopolysiloxane and then placing the polymer in a devolatilizing extruder and mixing other ingredients such as fillers. Alkoxy functional one-component type with low viscosity, quick curing and storage stability.
An object of the present invention is to provide an RTV silicone rubber composition. These and other objects of the invention are achieved by the disclosure set forth below. In accordance with the above objectives, stable, substantially anhydrous and substantially acid-free organometallic materials which can be converted into stable, tack-free elastomers under substantially moisture-free ambient conditions for extended periods of time. A continuous process for making polysiloxane compositions is provided by the present invention, which process comprises: (a) an organopolysiloxane in which the silicon atom at the end of each polymer chain is terminated with at least one hydroxy group; ) a polyalkoxy crosslinker or a composite crosslinker scavenger; (c) an endcapping catalyst which is an acid selected from Lewis acids, Lowry-Brensted acids and stearated calcium carbonate; (d) primary, secondary and a tertiary amine are passed through a static mixer, and the resulting mixture is then passed through a devolatilizing extruder while the other components are added to the devolatilizing extruder to RTV. By forming a composition. In the above method, the polymer is first end-capped with a polyalkoxysilane or composite crosslinker in a static mixer. Once such a polyalkoxy-terminated diorganopolysiloxane polymer is formed, the polymer is then mixed continuously with other ingredients at the desired stage in an extruder to produce the RTV silicone rubber composition. When all individual components, i.e. end-capped polymer forming components and other components such as fillers, adhesion promoters and condensation catalysts, plasticizers, etc., are added in the extruder, the viscosity of the resulting composition is very high. It is known. It is hypothesized that this high viscosity is due to the silanol groups in the filler reacting with the silanol groups in the silanol-terminated polymer prior to the alkoxy endcapping reaction that connects the hydroxy groups. As a result, substantial crosslinking occurs between the filler and the backbone polymer, resulting in excessively high viscosity. The viscosity of this composition does not decrease when the composition is left standing. In the compositions of the present invention, it is desirable to end-cap the backbone polymer along with the other components in a devolatilizing extruder. If a low viscosity uncured composition is not desired, the composition and all ingredients can be mixed in a devolatilizing extruder. For purposes of this invention, a scavenger is defined as any compound that links any free hydroxy groups in the composition. That is, unbonded −OH
reacts with unbound -OH to prevent it from further reacting in any polymer decomposition reactions in the composition, and is inert to all other components in the composition. be. A composite crosslinker scavenger is a compound in which one portion of the compound exhibits the same scavenging activity as the scavenger compound and the other portion endcapped the silanol-terminated diorganopolysiloxane polymer with one or more alkoxy crosslinking sites. is defined as a compound capable of endcapping a silanol-terminated diorganopolysiloxane polymer with one or more alkoxy groups. I have to point out just one point. End-capped diorganopolysiloxane polymers are one-component
Although it is desirable to have two or more alkoxy groups to form the main component of the RTV silicone rubber composition, if certain polymers are end-capped with only one alkoxy at the terminal end of the polymer, The composition is still one-component
Acts similarly to RTV compositions. Various viscosity reducing agents and plasticizers can be used in the present invention to reduce the viscosity of the final composition so that the final composition has a suitable application rate. However, such viscosity-lowering agents are preferably used in accordance with the present invention to produce one-component RTV silicone rubber compositions. Whatever viscosity reducing agents or plasticizers are used, these components reduce the final viscosity of the RTV silicone rubber composition. It is desirable to prepare the polyalkoxy-terminated diorganopolysiloxane polymer in a static mixer and then mix the compound with the other ingredients in a devolatilizing extruder in a continuous manner. It should be noted that the process of the present invention is completely continuous in nature, ie, the preparation of the uncured RTV silicone rubber composition and the mixing of all components during the package takes place in a substantially continuous manner. be. In order to produce the low viscosity RTV silicone rubber compositions of the present invention having application rates greater than about 50 to 100 g per minute, which correspond to the specific gravity range of the RTV compositions from 1.010 to 1.050, viscosity reducing agents and The plasticizer is a triorganosiloxy-terminated diorganopolysiloxane polymer of low viscosity, i.e., a viscosity of 10 to 10,000 centipoise at 25°C, and possibly a silanol-containing polymer of also low viscosity, i.e., at 25°C.
Must be used in compositions such as polymers with a viscosity of 1000 or less. It is believed that the scavenger described above absorbs the silanol groups in the low viscosity silanol polymer, rendering the polymer viscosity-lowering functional. In the broadest concept of the invention, all ingredients, ie, silanol polymer, filler, plasticizer, condensation catalyst, adhesion promoter, etc., can be mixed in a devolatilizing extruder. In such a substantially continuous process, the devolatilization extruder has a 40 to 100
Operated in the range up to 40 °C, but more preferably 40 °C
The extruder is operated with a slight vacuum to remove volatiles during the mixing process. However, the method of mixing all of the components described herein in a devolatilizing extruder is difficult to achieve in the uncured state and at high viscosities, i.e., at speeds of 50 to 100 g/min (1.010 to 1.01
It is known to give RTV products that tend to have a lower velocity (corresponding to the specific gravity of the uncured composition in the range of 1.050). This applicable speed range is
It should be noted that various compositions will vary according to the desired specific gravity of the particular RTV composition. Application speed is inversely proportional to specific gravity. Therefore, in accordance with a preferred embodiment of the invention:
It is desirable to first prepare the polyalkoxy-terminated diorganopolysiloxane polymer in a static mixer. The total amount of silanol end-stopped diorganopolysiloxane polymer and methyltrimethoxysilane crosslinker or broad range polyalkoxysilane crosslinker together with the endcapping catalyst or catalysts are initially mixed at 40 to 100°C in a static mixer. range,
Mixing is preferably carried out at a temperature range of 40 to 60°C. This mixing is accomplished in a substantially continuous manner to produce a polyalkoxy-terminated diorganopolysiloxane polymer. This polymer mixture is continuously fed to a devolatilizing extruder in which it is further mixed with other ingredients. The endcapping catalyst added together with the polyalkoxysilane crosslinker is preferably an acid alone or preferably
It can be either an acid with an amine cocatalyst as disclosed in No. 137883. However, for the process to operate continuously, the endcapping catalyst system must consist of the acid catalyst of Chiyoung European Patent No. 137,883 in combination with the basic amine catalyst described therein. . It is believed that endcapping will not be achieved at a sufficient rate if endcapping is carried out with only acid or amine catalysts such that it is extremely difficult to make the manufacturing process of RTV compositions truly continuous. Furthermore, it is not preferred to add a scavenger in the static mixer unless the alkoxy-terminated polymer is to be stored prior to mixing the remaining components in the devolatilizing extruder, otherwise the alkoxy-terminated polymer formed from the alkoxy-terminated polymer It should be noted that the cured silicone elastomer tends to become soft. If the alkoxy-terminated polymer is to be stored for a period of up to two years before forming the RTV silicone rubber composition from the alkoxy-terminated polymer, the scavenger compound can be added in a static mixer. If a composite crosslinker scavenger is used, the above does not apply since the crosslinker scavenger compound must always be added in a static mixer unless the silanol polymer is end-capped in a devolatilizing extruder. . Additionally, one-component RTV compositions cannot be cured with alkoxy-terminated diorganopolymer until tin or other types of condensation catalysts are added, since the compositions described below will not cure at a sufficient rate or to sufficient density without a condensation catalyst. It should be noted that it is formed from a siloxane end-capped polymer. The method of the invention can be applied to produce continuously or semi-continuously or in batches any one-component RTV composition as described above using a scavenger or a composite crosslinker scavenger. . Therefore, in a static mixer, a silanol-terminated diorganosiloxane backbone polymer is reacted with a polyalkoxysilane crosslinker of the formula below, and by continuous mixing, a polyalkoxy-terminated diorganopolysiloxane polymer is first prepared. is formed. The scavenger may be any scavenger, but is preferably silazane, more preferably hexylmethyldisilazane.
These scavengers can be added in portions in a static mixer to remove free hydroxy groups from the polymer mixture only if the composition is to be stored. When using a composite crosslinker scavenger in the present invention, it should be noted that the scavenger should not be added separately in the static mixer. The composite crosslinker scavenger will be added in a static mixer along with the end-coupled catalyst system and the silanol-terminated diorganopolysiloxane polymer. Furthermore, in a preferred embodiment of the present invention,
After continuously endcapping the silanol-terminated diorganopolysiloxane polymer with a polyalkoxysilane in a static mixer, the resulting polyalkoxy-terminated diorganopolysiloxane mixture is continuously transferred to the first step of a devolatilizing extruder. supply to. In the first step of the devolatilizing extruder, a polyalkoxydiorganopolysiloxane formed in a static mixer and a polyether sag (Sag) control agent as defined below and a trimethylsiloxy-terminated diorganopolysiloxane polymer, preferably A fumed silica filler, preferably treated fumed silica, is added to a plasticizer mixture consisting of a mixture of trimethylsiloxy-terminated dimethylsiloxane polymers having a viscosity in the range of 10 to 10,000 centipoise at 25°C. The devolatilizing extruder section is preferably operated under a slight vacuum, such as less than 20 inches of mercury. Preferably the devolatilizing extruder operates at a temperature in the range of 40 to 100°C, more preferably the entire process of the devolatilizing extruder operates at a temperature in the range of 40 to 60°C.
and operated under vacuum below 20 inches of mercury. Near the intermediate stage of the devolatilization extruder,
An amount of silazane scavenger in a preferred embodiment is added to the mixture to further link free hydroxy groups in the mixture. The preferred methods above and below are described with certain ingredients. However, it must be noted that, as far as the present invention is concerned, these components are merely exemplary. Other ingredients can be added to the alkoxy-terminated diorganopolysiloxane polymer in a different order than described below. In a preferred embodiment, the alkoxy-terminated diorganopolysiloxane polymer is first formed in a static mixer and it is only necessary to mix the other ingredients in a devolatilizing extruder in any order desired. Finally, in the last part of the devolatilizing extruder, a mixture of tin condensation catalyst and adhesion promoter and an excess of polyalkoxysilane crosslinker are mixed into the above mixture. The mixture is then mixed in a few more steps in the devolatilizing extruder and continuously extruded from the devolatilizing extruder. At that time, they are packaged continuously. Note that the adhesion promoter can be any adhesion promoter, but is preferably that disclosed in Lucas et al., U.S. Pat. No. 4,483,973, or other types of adhesion promoters. Must. Fumed silica is a polyalkoxy-terminated diorganopolysiloxane polymer
Triorganosiloxy-terminated diorganopolysiloxane plasticizers can be used in concentrations of 10 to 50 parts by weight, and sag control agents can be used in concentrations of 1 to 50 parts by weight per 100 parts by weight. Any up to 2 parts by weight can be used. The amounts used above are within their preferred usage ranges. Additionally, the devolatilizing extruder is preferably a twin-screw Werner-Frieder.
Pfleider) devolatilization extruder. Using such a method, i.e., a static mixer and a devolatilizing extruder, and mixing as described above, 1.030
Curing RTV while having an application rate greater than 50 g per minute corresponding to a specific gravity of the composition in the range of ~1.050
Silicone rubber compositions can be produced. Another preferred product formed in a devolatilizing extruder is to prepare the polyalkoxy-terminated diorganopolysiloxane polymer in a static mixer as described above and then take it to the beginning of the devolatilizing extruder. It is obtained by mixing with calcium carbonate and octamethylcyclotetrasiloxane-treated fumed silica in the step of . Furthermore, in the first step of the devolatilization extruder, a sagging control agent, 10-20000 at 25℃
A mixture of a triorganosiloxy-terminated diorganopolysiloxane polymer, preferably a trimethylsiloxy-terminated dimethylpolysiloxane polymer, having a viscosity in the centipoise range, and a combination of a plasticizer and/or an adhesion promoter is added. This combination comprises () 15 to 60 mole percent monoalkylsiloxy units or mixtures of such units, () 1 to 6 mole percent trialkylsiloxy units, and () 34 to 94 mole percent MTD plasticizers having dialkylsiloxy units, the plasticizers having about 0.1 to 2 weight percent silicon-bonded hydroxy groups. This mixture is then passed through a devolatilization extruder. An additional amount of scavenger is then added approximately halfway through the devolatilizing extruder. The scavenger in a preferred embodiment of the invention is a silazane scavenger. Near the end of the devolatilizing extruder, a condensation catalyst mixture consisting of an adhesion promoter and an excess of polyalkoxysilane crosslinker are then added. Mixing is then carried out in a few further stages in a continuous manner in a devolatilizing extruder, from which the RTV mixture is then continuously packaged and stored or shipped as is from the devolatilizing extruder. . Also, by using this method, uncured RTV silicone rubber compositions having application rates of 50 to 100 grams per minute or more and high amounts of calcium carbonate can be produced. Also for this product, the temperature of the devolatilization extruder is in the range of 40-60℃, more preferably
Preferably, the entire extruder is maintained under a vacuum of 20 inches of mercury or less in the range of 40-60°C. A vacuum is desirable to remove volatiles, especially moisture, that leave the mixture as it is being mixed. Preferably, in addition to the ranges indicated below, the polyalkoxy-terminated diorganopolysiloxane polymer 100
parts, 50 to 200 parts by weight of calcium carbonate, 0.1 to 2.0 parts by weight of polyether, 10
from 50 parts by weight of a triorganosiloxy-terminated diorganopolysiloxane polymer and from 2 to 20 parts by weight of a triorganosiloxy-terminated diorganopolysiloxane polymer;
A second preferred composition of up to parts by weight MTD plasticizer is used. The concentration of the components in the catalyst mixture per 100 parts of polyalkoxy-terminated diorganopolysiloxane polymer is:
Preferably it is an excess of polyalkoxysilane crosslinking agent. This excess polyalkoxycin crosslinker is used in both preferred methods of the invention in order to completely terminate the diorganopolysiloxane polymer with alkoxy groups if any alkoxy groups are hydrolyzed during the mixing step. . Even though the mixing method uses the particular type of preferred composition, the mixing process of the present invention is as disclosed for the alkoxy-functional one-component RTV system in White et al., U.S. Pat. No. 4,395,524 and related patents. It should be noted that it can be used to mix any and all ingredients. Furthermore, the continuous process of the present invention using a static mixer and devolatilization extruder has not been tested with all such compositions, but is described in the prior US patents disclosed above and below. It is believed that all the compositions and compositions of the components disclosed in this invention can be made. Preferred components and alkoxy-functional one-component RTVs that can be used and produced continuously according to the invention using a devolatilizing extruder with or without a static mixer
Compositions are disclosed below. The present invention, which involves continuous mixing in a devolatilizing extruder with or without a static mixer, is based on White et al.
It is believed that several compositions can be made such as those disclosed in No. 4,395,526 and other related patents mentioned above. The devolatilization extruder shall be any devolatilization extruder, such as a twin-screw Wernapfrider devolatilization extruder or a Buss or PBKokneader devolatilization extruder. I can do it. Having been described above, the various components and compositions that can be used in the methods of the invention are now more specifically described.
All such compositions and ingredients will not be disclosed below, but are mentioned in the US patents mentioned as prior art to the present invention. As mentioned above, all different acidic agents can be used as endcapping catalysts. By end-capping catalyst is meant a catalyst used in the reaction of a silanol-containing organopolysiloxane backbone polymer with a polyalkoxy-functional silane crosslinker or a composite crosslinker scavenger. A third type of acidifying agent that has been found to work in the present invention is stearate treated calcium carbonate. Stearate-treated calcium carbonate has been found to catalyze the endcapping reaction of alkoxy-functional silazane composite cross-linked scavengers according to the present invention. This catalytic action is assumed to be due to the presence of stearic acid in the stearic acid-treated calcium carbonate. However, this is just a hypothesis. As such, such calcium stearate carbonate also catalyzes the endcapping reaction of any other complex crosslinker scavenger compound or polyalkoxy functional crosslinker such as methyltrialkoxysilane, preferably methyltrimethoxysilane. It is assumed that however,
Again, this is just a hypothesis. In addition to stearate-treated calcium carbonate, the types of acidifiers that fall within the broad definition above include, of course, traditional acid anhydrides, traditional inorganic acids, traditional silane acidifiers, and traditional organic acids. There is. Additionally, included within the above broad definition are traditional acids classified as Lewis acids, such as aluminum chloride and the like. However, before discussing the definition of such acids, it is necessary to consider some limitations regarding the use of such acidifying agents in endcapping reactions. First of all, the concentration of acid used must be at least the effective amount necessary to promote the endcapping reaction. The concentration of acidifying agent should not be so high as to cause or catalyze the breaking of any of the siloxane bonds in the silanol-containing organopolysiloxane compound that is being endcapped. In other words,
Preferably, the acid value of the acidifying agent in the reaction medium is determined by General
Electric Company Silicon Products Department
at least 0.1 according to the C204 test method;
The acid value is such that it is determined that it should not exceed 15. Briefly, the C204 test method consists of using a 250 ml flask and adding 100 ml of isoprophenol and 0.25 ml of phenolphthalein indicator to the flask. The sample whose acid value is to be determined is then weighed and added to the flask. The resulting solution is titrated with 0.1N KOH (in methanol) to a pink endpoint. The amount of KOH in methanol used in the titration is recorded as _Vt . Then, the total acid value is calculated using the following formula. Total Acid Number = V _t (NKOH) 56.1/Sample Weight Another way of saying the above is that the total acid number is the number of mg of KOH that neutralizes the free acid in 1 g of sample. Generally, for most acidifying agents of the type disclosed above, this means that the acid concentration of the acidifying agent must be in the range of 0.01 to 0.5 parts by weight per 100 parts by weight of the silanol-containing organopolysiloxane. It means that. It is noteworthy that most of the acidifying agents as disclosed in this invention result in faster endcapping reactions than are experienced with relatively slow basic endcapping catalysts such as amine catalysts. Nevertheless, in one embodiment of the present invention, the rate of the acidifying agent when used as an endcapping catalyst is such that the acidifying agent is
Further enhancement can be achieved by combining traditional basic amine catalysts such as those disclosed in US Pat. No. 4,395,526. All amines, whether sylated or complete, in one form or the other,
Cocatalysts can be used within the scope of this invention including primary, secondary and tertiary amines. The more basic the amine, the more effective it is as a catalyst. Examples _of preferred amines that can be used within the scope of _the invention are, for example ( _Me2N ) ₂ -C= _{NC3H7Si ( OCH3} ) ₃ ( _Me2N ) ₂ -C= _NC4H9H2 NC ₃ Si (OEC) ₃ H ₂ NC ₃ H ₇ Si (OCH ₃ ) ₃ H ₂ NC ₃ H ₇ NC ₃ H ₇ Si (OCH ₃ ) ₃ diefamine T-403 Tetramethylpiperidinepiperidine 1,4-diazobicyclo[ 2.2.2] Octane N-methylmorpholine N,N-dimethylethylenediamine N-methylpiperidine N-hexylamine tributylamine dibutylamine cyclohexylamine di-N-hexylamine triethylamine benzylamine dipropylamine N-ethyl phenylamine . Thus, primary, secondary, and sylated secondary amine silanes are used as acidifying agents of the present invention to further increase the rate of endcapping over that achieved by the acidifying endcapping catalyst itself. Can be used in combination with The primary, secondary, and tertiary amines described above and the sylated amines disclosed above are merely exemplary, and any type of such amine may be used in combination with the acidifying agent of the present invention to form an endcapping cocatalyst. It should be noted that it can be used as Generally, such amines, when used as endcapping catalysts, are used at concentrations anywhere from 0.1 to 1.0 parts by weight per 100 parts by weight of the silanol-terminated diorganopolysiloxane polymer to be endcapped. However, such use of a basic cocatalyst in combination with the acidification catalyst of the present invention is optional. However, such basic catalysts are necessary if the process is to be continuous. In other cases, such basic amine promoters are not necessary. Thus, in many cases, the acidifying agents of the present invention perform and catalyze endcapping reactions for which sufficient efficiency is desired. Regarding the alkoxy-functional silazane composite crosslinker scavengers of Chiyoung et al., U.S. Pat. It is noteworthy that it promotes the blockade reaction. Preferably, such acidifying agents are used as endcapping catalysts in the present invention at the concentrations indicated above.
Preferably, the acidification catalyst, which in particular applies to inorganic acids, must have the above-mentioned acid number in the reaction medium. This is especially true regarding the maximum acid number. If the acid number exceeds the maximum value indicated above, the acidifying agent is present during the immediate reaction period or subsequent period during which the composition is formed and stored before use, or indeed when the siloxane elastomer is formed. Even then, it may have a tendency to catalyze the breaking of siloxane bonds. It is therefore particularly desirable not to exceed the maximum acid number indicated above, generally not to exceed 15, preferably not to exceed 5 as determined by method C204. Any of the acidic catalysts can be used alone as described above or in combination with one of the amine cocatalysts defined above. This amine cocatalyst is a prior art amine end-capped catalyst, within the concentrations indicated above and for the reasons indicated above. However, as pointed out, in most cases this is not necessary. Additionally, as noted, for most endcapping reactions, the acid/amine endcapping catalysts of the present invention are significantly more efficient than the basic amine catalysts of the prior art. Referring to reactions in which such acidification catalysts are used, such acidification catalysts can be used to synthesize silanol-containing organopolysiloxane polymers, more preferably silanol-terminated polymers, from polyalkoxy-functional silanes or from the aforementioned US patents, particularly White et al. US Patent No.
4395526 and Zudziak et al.
Alkoxy-functional one-component type intended for end-capping with either one of the alkoxy-containing composite crosslinker scavengers disclosed in No. 4417042.
With respect to RTV-type compositions, any of the compositions and reactions discussed as prior art to the present invention may be used. The endcapping reaction is one in which polyalkoxy-terminated diorganopolysiloxane polymers are initially formed according to the disclosure of the White et al. patent, in which a scavenger is added during or subsequent to the reaction. must be pointed out. This scavenger acts to link all free hydroxy groups in the RTV polymer composition to maintain storage stability of the composition. In the most preferred form, the end-capping catalyst of the present invention has the following formula, which is a crosslinking agent that is more preferably used to produce an end-capping polymer:
Used in the reaction of polyalkoxy-functional silane (4). This crosslinking agent reacts with the backbone silanol-containing diorganopolysiloxane polymer to form a polyalkoxy-terminated diorganopolysiloxane backbone polymer to which a scavenger is added according to White et al., US Pat. No. 4,395,526. The polyalkoxy-terminated diorganopolysiloxane polymer is preferably first formed using a polyalkoxy-functional silane of formula (4) below or by using a composite crosslinker scavenger. This is the most preferred method of forming the RTV polymer compositions of the present invention. In order to facilitate and increase the efficiency of the endcapping reaction, it is desirable to use one of the endcapping acid/amine catalysts of the present invention. Without such an end-capping catalyst, either a basic catalyst or an acidic catalyst, the polyalkoxy-functional silane of formula (4) would react only slowly, if at all, with the silanol-containing organopolysiloxane. . Therefore, in order to commercialize this reaction, accelerate the manufacturing process, and from the point of view of economic benefits, it is highly desirable to use an end-capping catalyst consisting of an acidifying agent and a basic amine. The above is based on Zdziak's U.S. patent no.
It is particularly desirable if the end-capping polymer is formed before adding the scavenger to the RTV system as disclosed in US Pat. No. 4,417,042. Additionally, as noted when endcapping silanol-terminated diorganopolysiloxane polymers of formula (1) using a combination of composite crosslinker scavengers, the endcapping catalyst of the present invention can be promoted to be as efficient as possible. In order to facilitate the endcapping of the silanol-terminated diorganopolysiloxane polymer of formula (1), it is necessary to reuse one of the acidified endcapping catalysts of the present invention. Therefore, preferred RTV systems in which the acidification catalysts of the present invention may be used to form end-capped polymers are described. It should be understood that these catalysts may generally be used in any endcapping reaction between an alkoxy-functional silane and a silanol-containing organopolysiloxane polymer. Silanol-terminated polyorganosiloxane has the formula where R is a C _1-13 monovalent substituted or terminally substituted hydrocarbon group, preferably methyl, or a mixture of a large amount of methyl and a small amount of phenyl, cyanoethyl, trifluoropropyl, vinyl and their like. a mixture, where n is an integer having a value from about 50 to about 2500. This is a crosslinker silane that has a hydrolyzable group attached to the silicone. The term "stable" as applied to the one-package polyalkoxy-terminated organopolysiloxane RTV of the present invention, as used below, means substantially unchanged during exclusion of atmospheric moisture and unchanged after long-term storage. Refers to a moisture-curable mixture that cures into a tacky elastomer. Additionally, a stable RTV also has a tack-free time exhibited by freshly mixed RTV components under ambient conditions, but remains moisture resistant and moisture-free for an equivalent period of time under ambient conditions or with accelerated degradation at elevated temperatures. Means the same amount of time exhibited by the same mixture components exposed to atmospheric moisture after storage in a container. Stable, substantially acid-free, one-package, moisture-curable polyalkoxy-terminated organopolysiloxane RTV compositions, such as the silanol-terminated polydiorganosiloxane of formula (1) A silanol-terminated polydiorganosiloxane consisting essentially of chemically bonded diorganosiloxane units can be prepared using an effective amount of a silane scavenger for the chemically bonded hydroxy groups. In the above formula, R is as defined above. In silanol-terminated polydiorganosiloxanes consisting essentially of chemically linked units of formula (2), such as methoxy groups,
The presence of silicon combined with C _1-8 alkoxy groups is not excluded. The hydroxy groups eliminated by the silane scavenger include the silanol groups of the materials normally present in the RTV compositions of the present invention, such as traces of water, methanol, silica filler (if used), formula (1) silanol polymers or silanol-terminated polymers having units of formula (2). In accordance with the practice of this invention, silane scavengers useful in scavenging chemically bound hydroxy groups are preferably of the formula , where R ¹ is a C _1-8 aliphatic organic group or a C _7-13 aralkyl group selected from an alkyl group, an alkyl ether group, an alkyl ester group, an alkyl ketone group, and an alkyl cyano group; , ^R2
is an organic group of C _1-13 value selected from the R groups defined above and more specifically below, and X is amide, amino, carbamate, enoxy, imidate, isocyanate, oximate, thio. Hydrolyzable leaving groups selected from isocyanate and ureido as well as other groups. Preferred groups are amino, amido, enoxy, more preferred groups are amides, such as N-C _1-8 acylamides, a is an integer of 1 or 2, preferably 1, and b is an integer of 0 or 1. and the sum of a+b is equal to 1 or 2. In formula (3) where a is 2, X can be the same or different. The leaving group X preferentially reacts with available -OH in the RTV composition over -OR ¹ to provide an RTV composition substantially free of halogenated or carboxylic acids. The silane scavenger of formula (3) is a silane scavenger for hydroxy functional groups and a polyalkoxysilane crosslinker for terminating the silicon atom at the end of each organopolysiloxane chain with at least two alkoxy groups. A component of the RTV composition formed as a result of using a hydroxy scavenger of formula (6) is a silanol-free polydiorganosiloxane chain-terminated with two or three -OR ¹ groups. The silanol-free polydiorganosiloxane can optionally be combined with an effective amount of a crosslinked silane as defined below under substantially anhydrous conditions. Crosslinked polyalkoxysilanes that can be used in combination with scavenger silanes of formula (3) are of the formula where R ¹ , R ² and b are as defined above. Preferred condensation catalysts that can be used in the practice of this invention include metal compounds selected from tin compounds, zirconium compounds, and titanium compounds or mixtures thereof. It is not entirely clear why the polyalkoxy-terminated organopolysiloxane compounds of the present invention are stable in the presence of certain condensation catalysts for extended periods of time in substantially moisture-free conditions. According to the present invention, the use of a scavenger silane of formula (3) or formula (5) below in combination with a crosslinked silane of formula (4) minimizes the formation of harmful R ¹ OH during storage. This theory is supported by mechanistic studies of the RTV of the present invention. R ¹ OH terminates the silanol polymer of formula (1) or the polymer having units of formula (2) to produce a polymer with terminal units of
Formation of R ¹ OH is avoided. These polymers in which the silicon atom at the end of each polymer chain is terminated with only one alkoxy group can have slow cure times. Additionally, R ¹ OH can decompose organopolysiloxane polymers in the presence of condensation catalysts. When a silane scavenger is used for hydroxy of formulas (3) and (5) where the leaving group X is not a halogen group,
Unwanted water in the filler and silicone polymer as well as residual moisture in the RTV composition during storage is substantially removed. By determining the amount of silane scavenger of formula (3) or (5) to be used in the practice of this invention, the total hydroxy functionality in the RTV composition can be estimated. The total hydroxy functionality of the polymer can be determined by infrared analysis. An effective or stabilizing amount of scavenger may be used to ensure the maintenance of stability of the composition over long-term storage periods of 6 months or more in closed containers at ambient temperatures. Additional scavenger can be used in excess of the amount required for termination. The scavenger can be up to about 3% by weight based on the weight of the polymer. The aforementioned 3% by weight of scavenger exceeds the amount required to substantially remove the hydroxy functionality obtained in the polymer as a result of the reaction between the OH functionality and the X group. In compositions that also include fillers and other additives, the additional amount of scavenger required by equations (5) and (6) is equal to the amount of free composition of the composition before degradation measured under substantially the same conditions. To determine whether the tack-free time is substantially unchanged compared to the tack time,
Estimated by checking stability for 48 hours at 100°C. In formulas (1 to 5), R is preferably selected from a C _1-13 monovalent hydrocarbon group, a halogenated hydrocarbon group, and a cyanoalkyl group, and R ¹ is preferably
It is a C _1-8 alkyl group or a C _7-13 aralkyl group, and R ² is preferably a methyl, phenyl or vinyl group. The definition of elastomers produced from the RTV compositions of the invention upon exposure to atmospheric moisture The expression "substantially acid-free" refers to a pKa of 5.5 or higher, preferably 6 or higher, particularly preferably higher than 10. This means that by-products with Additionally, it has been found that when small amounts of amines, substituted guanidines, or mixtures thereof are used as curing accelerators in the polyalkoxy compositions of the present invention, curing speed can be improved. In order to substantially reduce the tack-free time (TFT) of the RTV compositions of the present invention, per 100 parts of the silanol-terminated polymer of formula (1) or the same consisting of chemically bonded units of formula (2) or Polyalkoxy terminated polymer
From 0.1 to 5 parts per 100 parts, preferably about 0.3 parts
Up to 1 part of curing accelerator can be used. This increased curing rate results in long storage periods,
For example, after aging at ambient temperature for 6 months or more, and for a corresponding period under accelerated aging conditions, it is also possible to connect. The cure properties after an extended storage period are believed to be substantially similar to the initial cure properties, eg, tack free time (TFT) exhibited by a freshly mixed RTV composition immediately exposed to ambient moisture. In addition to reducing the tack-free time of the RTV compositions of the present invention, the curing accelerators described herein exhibit certain condensation catalyst-catalyzed specific compounds that exhibit significant lengthening of the tack-free time after accelerated aging. It also provides a surprising stabilized cure for RTV compositions. For this class of condensation catalysts, the addition of the amines, substituted guanidines, and mixtures thereof described herein exhibits rapid curing rates initially, i.e., in less than 30 minutes, and bonds virtually unchanged after accelerated aging. A stable RTV composition is obtained. The present invention also includes a method of making room temperature curable organopolysiloxane compositions using an effective amount of a condensation catalyst with a silanol-terminated organopolysiloxane and a polyalkoxysilane crosslinker under substantially anhydrous conditions. An improvement to this process is to add a hydroxy-functional scavenger and a formula (wherein R ¹ , R ² , X, a, and b are as defined above) by adding a stabilizing amount of a polyalkoxysilane crosslinking agent, and then adding an effective amount of a catalyst. In the room temperature curable composition obtained by this method, improved stability has been achieved. In a particular embodiment, (a) 100 parts of a silanol-terminated polydiorganopolysiloxane consisting essentially of chemical bonding units of formula (2); (b) scavenging the -OH in the RTV composition and formula sufficient to provide an excess of up to 3% by weight based on the weight of the organosiloxane composition.
(3) a certain amount of a silane of formula (4); (c) a mixture consisting of 0 to 10 parts by weight of a crosslinked silane of formula (4); ()(a) 100 parts of a polyalkoxy-terminated organopolysiloxane; (b) a mixture consisting of 0 to 10 parts of the crosslinked silane of (4), (c) an effective amount of a condensation catalyst, (d) a stabilizing amount of a silane scavenger, and, if necessary, (e) 0 to 5 parts of a curing accelerator. A method for producing a stable, one-package, room-temperature-curing polyalkoxy-terminated organopolysiloxane composition comprising stirring a room-temperature-curing material selected from: in a devolatilizing extruder under substantially anhydrous conditions. provided. The radicals R in formulas (1) and (2) include, for example, aryl and halogenated aryl groups such as phenyl, tolyl, chlorophenyl, naphthyl; aliphatic and cycloaliphatic groups such as cyclohexyl, cyclobutyl; methyl, Included are alkyl and alkenyl groups such as ethyl, propyl, chloropropyl, vinyl, allyl, trifluoropropyl; cyanoalkyl groups such as cyanoethyl, cyanopropyl, cyanobutyl. The group contained in R ¹ is preferably a C _1-8 alkyl group (for example, methyl, ethyl, propyl, butyl,
pentyl), C _7-13 aralkyl groups (e.g. benzyl, phenethyl), alkyl ether groups (e.g. 2-methoxyethyl), alkyl ester groups (e.g. 2-acetoxyethyl), alkyl ketone groups (e.g. 1- butan-3-oneyl group),
Alkylcyano group (e.g. 2-cyanoethyl)
It is. The group contained in R ² is the same as or different from the group contained in R group. Examples of the crosslinked polyalkoxysilane included in formula (4) include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane,
These include tetraethoxysilane and vinyltrimethoxysilane. Among the curing accelerators that may be used in the practice of this invention are:
Formula (Z) _g Si(OR ¹ ) _4-g (6) [In the formula, R ¹ is as defined above, and Z is the formula (wherein R ³ is a divalent C _2-8 alkylene group, R ⁴ and R ⁵ are selected from hydrogen and a C _1-8 alkyl group), and g is a guanidine group from 1 to 3. is an integer of ]. Furthermore, the expression Alkyl-substituted guanidines having the formula (wherein R ⁴ and R ⁵ are as defined above and R ⁶ is a C _1-8 alkyl group) can also be used. formula
Some of the silyl-substituted guanidines contained in (6) are
No. 4,180,642 and 4,248,993 to Takago. In addition to the above-mentioned substituted guanidines, e.g. di-n-
hexylamine, dicyclohexylamine, di-
A variety of amines are used, such as n-octylamine, di-n-butylamine, hexamethoxymethylmelamine, and silylated amines such as gamma-aminopropyltrimethoxysilane and methyldimethoxydi-n-hexylaminosilane.
Methyldimethoxy-di-n-hexylaminosilane acts as both a scavenger and a cure accelerator. Primary amines, secondary amines, silylated secondary amines are preferred, and secondary amines and silylated secondary amines are sometimes preferred. Silylated secondary amines such as alkyldialkoxy-n-dialkylaminosilanes and guanidines such as alkyldialkoxyalkylguanidylsilanes useful as curing accelerators also act as scavengers and, in some cases, It also acts as a stabilizer in the invention composition. Effective amounts of condensation catalysts that may be used in the practice of this invention to promote curing of RTV compositions include, for example,
(1) Silanol-terminated polydiorganosiloxane
It is 0.001 to 1 part per 100 parts by weight. Tin compounds include, for example, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dimethoxide, carbomethoxyphenyltin tris-uberate, tin octoate, isobutyltin triceroate, dimethyltin dibutyrate, dimethyltin dineodeconoate, triethyltin tartrate. , dibutyltin dibenzoate, tin oleate, tin naphthenate, butyltin tri-2-ethylhexoate, 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(ethyl acetoacetate), 1,3-propanedioxytitanium bis(acetylacetonate), diisopropoxytitanium bis(acetylacetonate),
These include titanium naphthenate, tetrabutyl titanate, tetra-2-ethylhexyl titanate, tetraphenyl titanate, tetraoctadecyl titanate, and ethyltriethanolamine titanate. Additionally, Weyenberg
The beta-dicarbonyl titanium compounds shown in US Pat. No. 3,334,067 can be used as condensation catalysts in the present invention. Zirconium compounds, for example zirconium octoate, can also be used. Other examples of metal condensation catalysts are, for example, lead 2-ethyl octoate, iron 2-ethylhexoate, cobalt 2-ethylhexoate, manganese 2-ethylhexoate, zinc 2-ethylhexoate,
These are antimony octoate, bismuth naphthenate, zinc naphthenate, and zinc stearate. Examples of non-metallic condensation catalysts are hexylammonium acetate and benzyltrimethylammonium acetate. Various fillers and colorants can be added to the silanol or alkoxy terminated organopolysiloxane. They include, for example, titanium dioxide, zirconium silicate, silica aerogel, iron oxide, diatomaceous earth, fumed silica,
Carbon black, precipitated silica, glass fiber, polyvinyl chloride, powdered quartz, calcium carbonate, etc. The amount of filler used can obviously vary within limits, depending on the intended use. For example, when used as a waterproofing agent, the curable compositions of the present invention can be used without fillers. For other applications, such as when the curable composition is used in the production of binders, higher amounts of filler, such as 700 parts or more per 100 parts by weight of organopolysiloxane, may be used. In such applications, the filler may consist of powdered quartz, polyvinyl chloride, or mixtures thereof, preferably a bulk filler having an average particle size ranging from about 1 to 10 microns. In connection with the present invention, the expressions "moisture-free conditions" and "substantially anhydrous conditions" are used below.
means mixing in a dry box or closed container that is evacuated to remove air and then replaced with a dry inert gas such as nitrogen. According to experience, the formula
(3) Scavenger silane should be used in a sufficient amount as clarified above. The temperature can vary from about 0°C to 180°C depending on the degree of mixing, type and amount of filler. Pursuant to Zudziak U.S. Pat. No. 4,417,042,
The scavenger can be a silazane.
Room-temperature curable organoposiloxane compositions are prepared by preparing an organopolysiloxane in which the silicon atom at the end of each polymer chain is terminated with at least two alkoxy groups in a static mixer, and then subjecting the end-capped polymer to devolatilization extrusion. It is prepared by mixing in-machine an effective amount of a condensation catalyst and a stabilizing amount of a silane scavenger for hydroxy functionality selected from the following classes of silicon nitrogen compounds: The class is (a) Equation (b) (1) where Y is selected from R and R″ ₂ N-;

【formula】

【formula】

【formula】

【formula】 【formula】

3 selected from a class consisting of units with [formula]
~100 mole percent chemically bonded structural units and formula (2) a silicon-nitrogen polymer consisting of 0 to 97 mole percent of chemically bonded structural units of The free valences of the silicon atoms, other than those bonded to each other by the oxygen forming the siloxy unit and the nitrogen forming the silazane unit, are selected from the R″ group and the (R) ₂ N group. and in which the R for the silicon atom of the silicon-nitrogen polymer
The ratio of the total number of groups and the above (R) ₂ N groups is
1.5 to 3, R'' is a member selected from the class consisting of hydrogen and monovalent C _1-12 hydrocarbon groups and fluoroalkyl groups; a member selected from hydrocarbon groups and fluoroalkyl groups, and c is an integer from 0 to 3) and optionally (3) substituted guanidines, amines, and mixtures thereof. The most preferred compound within the silicon-nitrogen compound formula is a silazane, and more preferably hexamethyldisilazane. Other compounds can be used as scavengers in the present invention, such as hydrogen-containing amines, as explained below. Within the present invention, such scavengers are not mixed crosslinker scavenger compounds. It is believed that, but rather, an independent cross-linking agent is used,
The silyl nitrogen material is a separate compound added to the composition. Thus, in a preferred embodiment of the invention, the crosslinking agent is first added to the silanol-terminated diorganopolysiloxane polymer in the presence of an endcapping catalyst.
A preferred endcapping catalyst for this purpose is one of the acidifying and basic amine catalysts of this invention. Once the polyalkoxy-terminated polymer is formed,
A scavenger, ie, one of the silicon-nitrogen compounds disclosed above, is then added in the devolatilizing extruder to adsorb any end-capped hydroxy groups. All other ingredients can then be added to the composition, and the scavenger will also absorb the free hydroxy groups of such materials.
Preparation of the composition by this method results in the preparation of a composition that is substantially free of hydroxy groups and therefore storage stable and rapidly curing. By storage stable, we mean that the rate and degree of cure six months or one year after manufacture is substantially the same as immediately after manufacture. In the above formulas of silicon-nitrogen compounds and silicon-nitrogen polymers, R'' and R groups can be selected from hydrogen and any monovalent hydrocarbon group (including fluoroalkyl groups).
Examples of groups from which R'' and R can be selected are, for example, alkyl groups such as methyl, ethyl, propyl, etc., cycloalkyl groups such as cyclohexyl, cycloheptyl, etc., phenyl, methylphenyl,
Mononuclear aryl groups such as ethyl phenyl, alkenyl groups such as vinyl, allyl, etc., 3,3,3
- a fluoroalkyl group such as trifluoropropyl. Generally R″ and R groups are from 1 to 12
more preferably the group can have from 1 to 8 carbon atoms. In addition to the silicon-nitrogen materials described above, the present invention also includes silicon-nitrogen materials having divalent hydrocarbon groups bonded to silicon atoms via silicon-carbon bonds. For example, silicon-nitrogen materials that may be used in the practice of the present invention also include arylene silazane, such as phenylene silazane, and alkylene silazane, such as methylene silazane. Additionally, various other silicon-nitrogen materials containing divalent hydrocarbon groups also include silicon-nitrogen materials containing co-condensed siloxane units and sylarylene silazane units, co-condensed silazane units, sylarylene siloxane units, and siloxane units, etc. It is also contemplated to include copolymers as well as terpolymers such as. The silicon-nitrogen polymer in the form of a silazane/siloxane copolymer has at least 3 mole percent chemically bonded siloxane units and up to 97 mole percent bonded siloxane units. Therefore, silazane polymers contain chemically bonded A cyclic product consisting of units (where R″ and R are as defined above such that the ratio of the total number of R and R″N groups to silicon atoms in the silabone polymer is 1.5 to 3.0) included. The definition of silazane polymer includes: units and at least one of _the class consisting of Linear polymers having one unit are included. Other silazane polymers included within the above definition of polymers are: The unit consists essentially of linear polymers (where R'' and R are defined such that the ratio of R and R''N groups per silicon atom in the silazane polymer is from 1.0 to 3.0). Furthermore, silazane polymers have units and (where R″ and R are as defined above such that the ratio of the total number of R and R″N groups per silicon atom in the silazane polymer is from 1.5 to 3). Polymers having at least one unit of Furthermore, silazane polymers are

【formula】 【formula】

where R″ and R are as defined above such that the ratio of the total number of R and R″ ₂ N groups per silicon atom in the silazane polymer is from 1.5 to 3. It can consist of a polymer having a sufficient amount of units to Silazane/siloxane copolymers can also be cyclic and have chemically bonded R
₂ SiO units and units in which R'' and R are as defined above. The linear silazane/siloxane copolymer includes: The mole percent of the unit is

【formula】

【formula】

where R″ and R are as defined above such that the ratio of the total number of R+R″N groups per silicon of the silazane/siloxane copolymer is from 1.5 to .30. residual units and
This includes those that are balanced at a level as high as 97 mole percent. Other linear silazane within the range of the above formula may be of the formula (wherein R″ and R are as defined above, n is a positive integer, preferably from 0 to 20
up to, d is an integer between 0 and 1, and d is 0
(n is preferably from 3 to 7)
It is a linear silazane with Examples of silazane that can be used in the practice of the invention within the above formula are hexamethylcyclotrisilazane, octamethylcyclotetrasilazane, trimethyltriphenylcyclotrisilazane, trivinyltrimethylcyclotrisilazane, and the like. In addition to the silazane of the above formula, a terminal silylamine unit or [wherein R″ and R are as defined above, and Z is R″ and SiR ₃ (wherein R″ and R
is as defined above) and n is as defined above]. The polysiloxane of the above formula can be prepared by taking ammonia or an amine and at a temperature within the range of about 0°C to 60°C, the polysiloxane of the formula (wherein R and n are as defined above and X is a halogen group such as chloro or bromo). If terminal silazane groups are desired, for example, a molar amount of (R) ₃ SiX can be reacted with at least an equimolar amount of the halogen atoms contained in the halogenated polysiloxane. Although it is of course appreciated that amines of the formula H ₂ NR'' (wherein R'' is as defined above) may be used to form the sillage chain-terminated polysiloxanes of the present invention, materials with terminal silylamine groups If desired, amines, including amines of the above formula, can be used to have at least one hydrogen available for the reaction to produce the desired polysiloxane. Accordingly, methods for making such polymers and compounds are well known. Such silyl-nitrogen compounds and silyl-
The existence of nitrogen polymers, along with their method of preparation, is disclosed in US Pat. No. 3,243,404, to which one skilled in the art may be referred for further information. In addition to the silyl-nitrogen compounds and silyl-nitrogen polymers described above, in the present invention (In the formula, R ²⁰ is a C _1-8 monovalent hydrocarbon group and
A group selected from the class consisting of C _1-8 alkoxy groups and fluoroalkyl groups, R″ is selected from hydrogen and C _1-8 monovalent hydrocarbon groups, and g
is an integer varying from 1 to 3, h is from 0 to 2
It is also possible to use scavengers that are silyl amines (an integer number varying up to 3, and the total number of h+g does not exceed 3). Compounds within the above formulas include, for example, methyldi(methylamino)silane, tris(methylamino)silane, methylbis(diethyl)silane and the following: (Methylamino)silane Ethyldi(ethylamino)silane Ethylbis(dimethylamino)silane. Such amines are disclosed in US Pat. No. 3,243,404 and can be prepared by the methods disclosed therein. Silyl-nitrogen compounds and polymers are most preferred as scavengers in the compositions of this invention. The above amine is of the present invention.
It can also be used as a scavenger in RTV compositions. The only drawback with hydrogenated amines is that they have a tendency to continually liberate hydrogen and also tend to add undesirable amine odor to RTV compositions. However, if this is not a problem, the amines are acceptable for use in the compositions of the invention. Preferably, silyl-
The nitrogen compound is used at a concentration of 0.5 to 10 parts per 100 parts by weight of the trunk organopolysiloxane polymer. Accordingly, preferred silyl-nitrogen compounds and polymers within the above formulas can be used in the present invention. As mentioned above, per 100 parts by weight of either silanol-based polymer or polyalkoxy-based polymer, preferably 0.5 to 10
Scavengers up to 100% are used. As explained below, there is little difference in the scavenger concentration whether the backbone polymer is silanol-terminated or polyalkoxy-terminated, since the molecular weights of both compounds are approximately the same. More generally, the scavenger can be used in concentrations from 1 part to any concentration desired. It is undesirable to add too much scavenger, as about 10 parts may reduce the curing physical properties of the composition. It is generally desirable to have at least 3% scavenger in the composition. That is, an amount of 3% or more is required to absorb or end-cap all free hydroxy groups in the composition. Further, in accordance with U.S. Patent Application Ser. Organopolysiloxane with formula (B) The acyclic silyl-nitrogen scavenger and the formula At least one or all of the units can be expressed as a cyclic silyl-nitrogen scavenger with the remaining units (if any) having [in the above three formulas, R ¹⁰ is selected from the group consisting of alkyl, alkyl ether, alkyl ester, alkyl ketone, alkyl cyano and aryl] is an aliphatic organic group, R ¹¹ is a C _1-8 monovalent substituted or unsubstituted hydrocarbon group, Q is hydrogen, C _1-8
Monovalent substituted or unsubstituted hydrocarbon group and formula (In the formula, R ¹⁰ and R ¹¹ are as defined above,
a then varies from 0 to 2, f varies from 0 to 3, h is 0 or 1, and s is 1.
is an integer varying from 1 to 25, d is an integer varying from 1 to 25, R ²² is selected from hydrogen and a C _1-8 monovalent hydrocarbon group, and R ²³ is 1
selected from hydrogen and hydrocarbonoxy groups, and A is hydrogen and
C _1-8 monovalent substituted or unsubstituted hydrocarbon group and formula (In the formula, R ¹⁰ and R ¹¹ are as defined above,
g varies from 0 to 3 and in said scavenger, at least one hydrocarbonoxy group is present in its molecule), and R ¹² is defined identically to R ¹⁰ . ,
R ¹³ is defined the same as R ¹¹ and R ¹⁴ is defined the same as R ¹¹ ] in a devolatilizing extruder. to form a stable, one-pack elastomer that can be converted into a long-term stable, tack-free elastomer under substantially moisture-free ambient conditions by mixing the formed polymer with a condensation catalyst and other components. , a continuous method of forming a substantially anhydrous, substantially acid-free, room temperature curable organopolysiloxane composition is provided. If it is desired to have a composite crosslinker scavenger compound with s = 1 and d = 1 in the RTV system, at least 3, preferably 4 alkoxy or hydrocarbonyl groups are present in the linear or cyclic silazane compound. The compounds disclosed above can be used, with the exception of those compounds in which there is an oxy group, or one alkoxy group on each silicon atom of the cyclic compound. When s and d are greater than 1, some components or polymers generally also act as composite crosslinkers with silicon atoms free of hydrocarbonoxy groups, but preferably silicon-terminated There are at least two hydrocarbonoxy groups attached to the atoms and one hydrocarbonoxy group attached to each internal silicon atom. Although two or one alkoxy groups in a compound can effectively act as a scavenger for the compound, unfortunately the compound does not have sufficient alkoxy functionality to provide the necessary crosslinking ability to the composition. does not have. Additionally, all of these alkoxy compounds can also be prepared by traditional methods, such as those disclosed in Zudziak, US Pat. No. 4,417,042, dated February 17, 1982, cited above. In the formula of a linear or branched acyclic silyl-nitrogen scavenger, the group R ¹⁰ is an alkyl group such as methyl, ethyl, propyl, etc.; methyl methyl ether, methyl ethyl ether, methyl propyl ether, ethyl ethyl Alkyl ether groups such as ether, ethylpropyl ether, 2-methoxyethyl, 2-ethoxyethyl, 2-propoxymethyl, etc.; methyl ester, ethyl ester, propyl ester, butyl ester, 2
-alkyl ester groups such as acetoxyethyl, 2-acetoxypropyl, etc.; 1-butane-3-
Alkyl ketone groups such as onyl, methyl methyl ketone, methyl ethyl ketone, ethyl methyl ketone, ethyl ethyl ketone etc.; alkyl cyano groups such as methyl nitrile; aryl groups such as phenyl, methyl phenyl etc. Basically, the R ¹⁰ group is any alkyl and phenyl group having 1 to 8 carbon atoms, more preferably one of the groups disclosed above. Most preferably R ¹⁰ is selected from methyl. In the compound of formula (13), R ¹¹ is generally; an alkyl group such as methyl, ethyl, propyl, etc.; a cycloalkyl group such as cyclohexyl, cycloheptyl, etc.; an olefin group such as vinyl, allyl, etc.; such as monocyclic aryl groups such as phenyl, methylphenyl, ethyl phenyl, etc.
A C _1-8 monovalent substituted or unsubstituted hydrocarbon group or a substituted hydrocarbon group such as a fluoroalkyl group such as 3,3,3-trifluoropropyl is selected. The group R ²³ is independently selected from the same groups as R ¹¹ and a C _1-8 hydrocarbonoxy group. Furthermore, R ²² is selected from hydrogen and the same groups as R ¹¹ . Thus, preferably R ¹¹ is selected from alkyl groups having 1 to 8 carbon atoms, most preferably from hydrogen. On the other hand, the group Q can be any group defined for R ¹¹ with the caveat that the carbon atoms in the group are preferably 8 or less.
It can be selected from any C _1-8 monovalent substituted or unsubstituted hydrocarbon group. The other part of the definition of the compound of formula (10) is that a is 0 to 2
, f varies from 0 to 3, Q is selected from hydrogen and a C _1-8 monovalent hydrocarbon group, the total number of a + f does not exceed 5, and the formula
At least one alkoxy group is present in the compound (10). The reason for this restriction regarding a and f is to ensure that a and f correspond to the description of the silazane compound of the present invention and that at least one alkoxy group is present in the molecule. Process of the invention, in which the compound of the invention is different from the compound of Zudziak US Pat. No. 4,417,042
It should be noted that is the presence of a hydrocarbonoxy group in the compounds of the invention.
No hydrocarbonoxy group is present in the compounds of the Zudziak US patent. The advantages of the hydrocarbonoxy group of the present invention are as explained above. Furthermore, in the definition of the compound of formula (10), preferably s is an integer varying from 1 to 25, most preferably 1, and d is preferably an integer varying from 1 to 25, most preferably Preferably it is 1-10.
Relatively simple alkoxysilazane compounds should be desired because they are the most easily obtained and are obtained in the highest yields. However, relatively high molecular weight hydrocarbonoxylazan compounds can also be used in the present invention within the scope of the above formula. Furthermore, in formula (10) above, A is preferably the same as defined above with respect to hydrogen and R ¹¹
selected from the class consisting of C _1-8 monovalent substituted or unsubstituted hydrocarbons; Most preferably A can be selected from hydrogen, methyl or ethyl groups. -Si _{(CH3)3, -Si(OCH3)(CH3)2, -Si(OCH3)2(CH3), -Si(OCH3 ) 3Compounds of formulas ( 13 ) and (} 14) above For example, in embodiments when the silazane compound is a scavenger, it is preferred that R ¹⁰ and R ¹¹ are methyl and the Q group is hydrogen. In addition to the linear and branched acyclic silazane compounds described above, alkoxy-functional cyclic silazane compounds can be used in the present invention. Therefore, at least one or all of the units of formula (14),
and a cyclic silyl-nitrogen scavenger having the remaining units (if any) of formula (15). Preferably, the compound consists of units of formula (14), but the cyclic compound can also have interspersed units of formula (14) of formula (15). However, it should be noted that the cyclic compound must have at least one hydrocarbonoxy or alkoxy group in the compound as well as it must be a cyclic silazane compound that can be used in the present invention. It takes. In the present invention, a hydrocarbonoxysilazane compound having at least one hydrocarboxy group in the compound, either linear or cyclic, and s=
It should be noted that there is a difference between hydrocarbonoxysilazane compounds having at least 3 or 4 hydrocarbonoxy groups in the compound when 1 and d=1. Those having at least one but less than three alkoxy groups can be used only as scavengers in the present invention. at least 3 or 4 hydrocarbonoxy groups when s=1, d=1 or more hydrocarbonoxy groups when s and d are greater than 1 according to the above disclosure The hydrocarbonoxy compounds of the invention can be used both as scavengers and as composite crosslinking agents. That is, when used in appropriate amounts, the compound cross-links the backbone silanol material to form an alkoxy-endcapped diorganopolysiloxane polymer that hydrolyzes upon exposure to ambient moisture to form a silicone elastomer. It also acts as a crosslinking agent to link unbound hydroxy groups in the polymer mixture. Furthermore, compounds having at least three or more hydrocarbonoxy groups, regardless of whether the compound acts as a composite crosslinking agent,
It should be noted that it can also be used as a scavenger. In any case, if a crosslinking agent is used and the silazane compounds have at least three hydrocarbonoxy groups, some of the hydrocarbonoxysilazane compounds will be scavenged by statistical reaction products of the composition. Like Yar,
It is thought to act as a crosslinking agent. In this regard, hydrocarbonoxysilazane compounds having less than three hydrocarbonoxy groups are suitable for s=1, Q according to U.S. Pat. No. 4,720,531.
It should be noted that although there may be an exception in the case of =H, it only acts as a scavenger and must be used with this in mind. As for the amount of compound used, as discussed elsewhere in this invention, a guideline is 1 to 12 parts, more preferably 3 parts per 100 parts by weight of silanol polymer.
Up to 7 parts of a hydrocarbonoxysilazane compound can be used. When the hydrocarbonoxysilazane compound acts both as a crosslinker and as a scavenger, there will generally be from 2.0 to 12 parts of the hydrocarbonoxysilazane compound, preferably the trunk silanol, per 100 parts by weight of the trunk silanol polymer. 3 to 8 parts of the compound are used per 100 parts of polymer. These concentration ranges are common, especially in the second case. This is because the amount of hydrocarbonoxy compound used both as a crosslinker and scavenger depends on the amount of hydrocarbonoxy groups in the hydrocarbonoxy compound molecule. Furthermore,
The cyclic silazane compound can be any cyclic silazane, but is most preferably trisilazane or tetrasilazane. This is because these are the most easily available cyclic silazane. However, pentasilazane or higher cyclosilazane can also be used. It must be recognized that in the usual process for producing such cyclic silazane, most of the compounds produced are cyclic tetrasilazane and cyclic trisilazane. However, some higher cyclic silazane have also been prepared, and these higher cyclic silazane in mixtures with cyclic trisilazane and cyclic tetrasilazane, according to their hydrocarbonoxy functionality, as described below. It can be used as a scavenger or as both a scavenger and a crosslinking agent in the present invention. For a silazane to act as a crosslinker as well as a scavenger, there must be at least three hydrocarbonoxys present in the silazane molecule because the endcapping group connects the silanol groups at the end of the polymer. This is because when doing so, it is desirable to add at least two alkoxy groups to the silyl group. In such cases, i.e., when the majority of the polymer is terminated with at least two hydrocarbonoxy or alkoxy groups,
The stem polymer thus terminated is storage stable;
Effectively crosslinks to produce storage stable compositions.
The remaining hydrocarbonoxysilazane can readily act to link other terminal hydroxy groups present in the polymer mixture other than the terminal hydroxy groups of the silanol-terminated diorganopolysiloxane backbone polymer. Furthermore, as noted above, although the above concentration ranges are given for silazane compounds, these concentrations are quite general, whether used solely as a scavenger or as a scavenger and crosslinking agent. This is a guideline, not a limit. What is important is that a minimum amount of silazane compound is present, whether as a scavenger alone or as both a scavenger and a composite crosslinker. Therefore, the minimum amount of this silazane compound is at least 3% excess of the stoichiometric amount needed to react with any excess water and any excess unbound hydroxy groups in the polymer mixture, and is generally In most compositions, a level of at least 1 part by weight of the scavenging silazane compound per 100 parts of the trunk silanol-terminated diorganopolysiloxane polymer can be determined. When a composite crosslinker scavenger can be used, it is preferred to catalyze the end-closure reaction with the catalyst of the present invention and the scavenger added in a static mixer. For further information regarding these alkoxy-functional silazane as composite crosslinker scavenger silazane, see Chiyoung et al., US Pat. No. 4,720,531. Before describing embodiments, it is necessary to clarify the main points of the present invention. First of all, for the silanol-terminated organopolysiloxane polymers of formula (1), it is preferred that the silanol groups are present on the terminal silicon atoms. Such polymers, i.e. the formula
In the polymer of (1), several silanol groups can be present in the polymer chain. Such silanol groups in the polymer chain slightly cause more crosslinking during curing of the polymer. If there are too many silanol groups in the polymer chain, it may be difficult to fully cure the polymer. However, preferably the majority of the silanol groups are present at the terminal silicon atoms in the polymer chain of the polymer of formula (1). The second point to point out is the formation of end-stopped polymers produced by the reaction of either a polyalkoxy-functional silane crosslinker or a composite crosslinker scavenger reacting with a silanol-end-stopped diorganopolysiloxane polymer. In , after forming such end-stopped polymers, there may be some polymers with only monomethoxy groups at one or both ends of the polymer chain. Not all polymers must be of this particular type. That is, if this is the case, considerable difficulties may be encountered in curing the composition. Thus, in order to have an adequate cure rate or to have a rapidly curing RTV composition, it is desirable to have polyalkoxy groups on the terminal silicon atoms of most of the polymers in the RTV composition. Finally, as mentioned above, previous amine endcapping catalysts are suitable for endcapping for composite crosslinker scavengers used to endcap silanol-terminated diorganopolysiloxane polymers such as those of formula (1). Acts very effectively or not at all as a catalyst. In the case of the alkoxy-functional silazane composite crosslinker scavenger of Chi Young et al., US Pat. No. 4,720,531, the traditional basic amine end-capping catalyst acts only poorly as an end-capping catalyst. The end-capping acidifiers of the present invention are by far the best end-capping catalysts for such materials and continuous processes and must be used in combination with amines. RTV compositions of the invention are storage stable;
A preferred method of making low modulus, non-corrosive, fast-curing compositions is to use polyalkoxy-terminated diorganopolysiloxane polymers, i.e., the polyalkoxydiorganopolysiloxane is first formed and the hydroxy groups in the composition are is removed or captured and then the desired other components are added. This method involves adding a silanol polymer of formula (1) to a crosslinking agent of formula (4), i.e., pre-reacting the silanol polymer with a crosslinking agent, preferably a catalyst and preferably is made in the presence of an end-capping catalyst,
This is then done by taking the di- or trialkoxy end-capped polymer and adding a scavenger to absorb the silanol groups. Other ingredients can then be added to the composition under substantially anhydrous conditions to produce a one-component RTV package. This RTV composition is storage stable and cures at a sufficiently fast rate, ie, even with the tin soap catalyst in the composition. The above method [i.e., the polyalkoxy material is 100 parts by weight of diorganopolysiloxane base polymer (i.e., formula (1) is converted into 100 parts by weight of silanol polymer, or 100 parts by weight of polyalkoxy-terminated organopolysiloxane polymer)
2 to 20 parts by weight] after manufacturing the above RTV system according to
The first basic component according to the invention that can be added to an RTV system is initially a plasticizer fluid polysiloxane. It contains a high degree of trifunctionality or a mixture of tri- and tetrafunctionality, () from 5 to 60 mole percent monoalkylsiloxy, siloxy units or mixtures of such units, () from 1 to 6 mole percent. trialkoxysiloxy units and () 34 to 94 mole percent dialkylsiloxy units, wherein the first plasticizer polysiloxane contains from 0.1 to about 2 weight percent silicon-bonded hydroxy groups. The polysiloxane first plasticizer polysiloxane fluid can be added generally at a concentration of 2 to 20 parts by weight of backbone polymer, or more preferably at a concentration of 5 to 15 parts by weight per 100 parts of backbone polymer. must be pointed out. Such polysiloxanes act as plasticizers and adhesion promoters and especially as plasticizers in the compositions of the invention. It is undesirable to exceed 20 parts per 100 parts by weight of backbone polymer. Therefore, it is generally not used in an amount exceeding 20 parts by weight, and has no effect if used in an amount below 2 parts by weight. Preferably, this fluid is heated between 15 and 300 at 25°C.
It has a viscosity in the centipoise range. Preferably, the fluid polysiloxane plasticizer also includes:
At least 50% of the alkyl substituents are methyl and the fluid consists of 0.2 to 0.6% by weight silanol. Particularly preferably monoalkylsiloxy units, siloxy units or mixtures thereof are comprised from about 10 to 30 mole percent, trialkylsiloxy units are comprised from 3 to 5 mole percent, and dialkylsiloxy units are comprised from about 3 to 5 mole percent.
65 to 85 mole percent and the silanol content is about 0.2 to 0.6 weight percent. Thus, although such trifunctional fluids plasticize the base composition to make it low modulus, in all cases they do not make it sufficiently low modulus, nor do they alone make it sufficiently low viscosity. Therefore, from 10 to 100 parts of the above-mentioned trunk organoposiloxane polymer.
It is highly desirable that up to 50 parts by weight of a second plasticizer be present in the 100 parts backbone polymer used in addition to the trifunctional fluid. As mentioned above, by backbone organopolysiloxane polymer is meant either the silanol-terminated diorganopolysiloxane polymer of formula (1) or the polyalkoxy-terminated diorganopolysiloxane polymer, or various mixtures of both. Because the alkoxy groups add very little to the molecular weight of the polymer, the concentrations of the various additives in addition to the trifunctional fluid discussed below are substantially the same as those described in the section for either polymer system. seems to be the same. Therefore, the trunk organopolysiloxane polymer
From 5 to 60 parts by weight of second plasticizer per 100 parts by weight can be used. This plasticizer is a linear triorganosiloxy-terminated diorganopolysiloxane polymer whose viscosity ranges from 10 to 10 at 25°C.
The organic groups are selected from C _1-8 monovalent hydrocarbon groups. More preferably, these monovalent hydrocarbon groups are alkyl groups of 1 to 8 carbon atoms. Thus, preferably the second plasticizer has the formula (wherein R ²⁰ is a monovalent hydrocarbon group, preferably a C _1-8 carbon atom alkyl or phenyl group or generally a C _1-8 alkyl or aryl group, and t is a polymer the viscosity of which varies from 10 to 20,000 centipoise at 25°C). Most preferably the ^R20 group is methyl and the polymer has a temperature of 10 to 10000 at 20°C.
It has a viscosity varying up to centipoise, preferably from 10 to 1000 centipoise at 25°C. Generally, depending on the method of manufacture, such polymers have from 500 to 1500 parts of OH per million parts of silanol. Above formula (15)
A common method for making such plasticizers is to hydrolyze the appropriate chlorosilane. Thus, triorganochlorosilane is hydrolyzed with diorganodichlorosilane in water, and the hydrolyzate is then removed.
Purification by decanting and other methods used to yield the desired linear diorganopolysiloxy polymer of formula (15). Such polymers by this conventional hydrolysis method are silanol as OH.
It usually has 500 to 1500 parts per million parts and can be further purified by other methods. However, such hydrolysis is usually not carried out because it is expensive. Furthermore, such silanol or hydroxy groups do not appear to present difficulties in the context of the present invention, provided there is a scavenger that absorbs substantially all the hydroxy groups present in such polymers. As previously stated, a scavenger that absorbs all free hydroxy groups in such plasticizers should be used in the system of the present invention. As mentioned above, in order to obtain the desired low values of composition modulus, two plasticizers should be used since trifunctional fluids alone will not produce an increase in both viscosity and modulus. Thus, it is necessary to use both plasticizers when it is desired to obtain minimum modulus, maximum adhesion, and minimum viscosity to enhance ease of waterproofing agent application. Accordingly, the most preferred low modulus one-component RTV systems of the present invention are prepared by using the two plasticizers of the present invention in the proportions described above. It should be noted that from 5 to 60 parts of the second plasticizer are used within the wide range mentioned above, preferably concentrations of 20 to 45 parts by weight. Another aspect is to reduce the cost of the composition. This composition is a trunk organopolysiloxane
Costs can be reduced by adding bulking fillers such as those described above in amounts of either 50 to 300 parts by weight or more per 100 parts. Extending fillers are desirable in the composition and increase the strength of the composition without reducing its low modulus properties. Most preferably the filler is calcium carbonate. The most desirable calcium carbonate is one that has been treated with stearic acid. This gives the final cured compositions of the invention the best flow properties and the best low modulus properties as defined above. Other bulking fillers can be added to the compositions of the present invention at the above concentrations of calcium carbonate disclosed above. Thus, other bulking and reinforcing fillers that can be used in various concentrations include, for example, titanium dioxide, zirconium silicate, silica aerogel, iron oxide, diatomaceous earth, fumed silica, carbon black, precipitated silica, glass fiber, polyvinyl These include chloride, powdered quartz, etc. The amount of filler used can obviously vary within wide limits, depending on the intended use. For example, in some waterproofing applications, as much as 700 parts or more of filler per 100 parts of organopolysiloxane, by weight, of the curable composition for making the bonding material is used. In such applications, the filler may consist of bulk fillers such as powdered quartz, polyvinyl chloride or mixtures thereof, which preferably range from about 1
It has an average particle size in the range up to 10 microns. However, the filler used at a concentration of 50 to 300 parts by weight should be a bulking filler such as calcium carbonate for the low modulus compositions of the present invention. from 1 to 50 parts by weight per 100 parts of trunk organopolysiloxane, in addition to extender fillers;
Preferably from 1 to 10 parts by weight of reinforcing filler is used. The reinforcing filler can be selected from precipitated silica and fumed silica, most preferably fumed silica. More preferably, fumed silicas are used which are treated with either cyclopolysiloxanes as disclosed in Lucas U.S. Pat. No. 2,938,009 or silazane as disclosed in Smith U.S. Pat. No. 3,635,743. It will be done. More preferably, 1 to 10 parts by weight of the above treated fumed silica treated with cyclopolysiloxane is used. Such fumed silica acts as a sag control agent making the composition thixotropic. Thixotropic means that the composition placed on a vertical surface does not flow or has minimal flow in the uncured state. Another way to make the composition thixotropic is by Lampe, referenced here.
No. 4,261,758. Thus, for every 100 parts of the backbone organopolysiloxane polymer having reinforcing fumed silica in addition to the extender filler, from 0.1 to 2.0 parts by weight of a second sag control agent per 100 parts by weight of the organopolysiloxane can be added to the RTV composition. . This control agent is A-O-(C _X H _2X O) _a -B and [In the formula, A and B are hydrogen, an alkyl group containing 1 to 12 carbon atoms, a cycloalkyl group containing 5 to 7 hydrogen atoms in the ring, a monocyclic and bicyclic aryl group, and a monocyclic aryl lower alkyl group. represents a group selected from the class consisting of groups in which the alkyl group bonded to the aromatic nucleus contains up to a total of 5 carbon atoms; (wherein R is alkyl containing from 1 to 11 carbon atoms), Q is from the class consisting of ethylene glycol, glycerin, trimethylolpropane and other polyhydric alcohols having from 2 to 6 hydroxy groups. residue of a polyhydric initiating group containing at least two selected hydroxy groups, n is a number having a value from 2 to 4, y has a value from 2 to 10, and z is a number from 1 to 5.
is a polyether selected from the formula consisting of This polyether has a molecular weight of about 300 to about 200,000. Polyethers, which are sag control agents, can be used in addition to or in place of fumed silica to impart thixotropic properties to the desired uncured RTV composition in waterproofing agents. Preferred RTV compositions of the present invention, i.e., compositions that are non-corrosive, low modulus, fast curing, storage stable and low modulus, are very suitable as waterproofing agents in structural building, glazing installation and other manufacturing industry waterproofing applications. We must pay attention to what is desirable. Therefore,
It is highly desirable that such waterproofing agents be thixotropic, ie, do not run off when inserted into a crevice in an uncured state. Such thixotropy can be incorporated into the compositions of the present invention by using small amounts of fumed silica in combination with the polyethers described above. Furthermore, this polyether is preferably combined with fumed silica.
Present from 0.1 to 1.0 parts by weight. Although fumed silica imparts sag control properties to the composition, these properties are significantly enhanced with the introduction of polyether. For further information regarding the use of polyethers as sag control agents, reference is made to the disclosure of Lampe, US Pat. No. 4,261,758, which is incorporated herein by reference. Examples of commercially available polyethers that can be used in the present invention are manufactured by Wyandotte Chemicals Corporation (Wyandotte Chemicals Corporation).
Pluracol V-7, sold by the Chemicals Corporation and Union Carbide Corporation of Connecticut.
A polyether such as UCON LB-1145. Instead of or in addition to both of these sag control agents, from 0.2 to 2.0 parts by weight per 100 parts by weight of the base organopolysiloxane, more preferably
From 0.2 to 1.5 parts by weight of hydrogenated castor oil can be used. An example of hydrogenated castor oil that can be used as a sagging control agent is that known as Thixcin (a trade name of NL Chemicals, Hightstown, New Jersey). Therefore, neither fumed silica nor polyethers should be used when hydrogenated castor oil is used as a sag control agent. However, when hydrogenated castor oil is not used as a sag control agent, fumed silica should be used with the polyether. Instead, fumed silica or polyether alone can be used. It must be emphasized that reinforcing fillers are not necessary in the compositions, as it is desired to have a low modulus in the compositions of the present invention. Large amounts of reinforcing filler appear to undesirably increase the modulus of the compositions of this invention.
Most preferably, the fumed silica (if used) is treated with calcium carbonate, especially stearic acid, which reduces the cost of the composition and maintains the viscosity of the uncured composition and the modulus of the uncured composition at low values. Used in addition to bulking fillers such as calcium carbonate. Various other types of additives may be added to the compositions of the present invention as they become available or are invented. Thus, per 100 parts of organopolysiloxane
From 0.1 to 10 parts by weight of adhesion promoter can be added to the composition of the invention. The compositions of the present invention, ie, White et al., do not bond as well to substrates. It is therefore desirable to use primers or adhesion promoters with such compositions. Primers are undesirable because they add additional labor costs to the waterproofing agent application. Therefore, it is highly desirable to use or incorporate self-bonding additives into the composition. Note, for example, the self-binding additives disclosed and listed in Lucas et al., US Pat. No. 4,483,973, incorporated herein by reference. Adhesion promoters that can be used in the present invention are described in the referenced Mitchell U.S. Pat.
This is mentioned in No. 4472590. Other adhesion promoters developed can be used in the compositions of the present invention in addition to those disclosed in the earlier Lucas et al. US Pat. No. 4,483,973. It is noteworthy that, among other properties, the compositions of the present invention are low modulus, fast curing and storage stable, and this low modulus property of the compositions is imparted by the plasticizer. When using the preferred extender filler of the present invention, the composition is also thixotropic by the addition of the thixotropic agent disclosed above;
Low cost. Any other adhesion promoter disclosed in Lucas et al. US Pat. No. 4,483,973 or the present invention can be used. Additionally, other additives that are developed can also be used in the compositions of the present invention. If the uncured silicone composition should have an application rate within the preferred ranges noted above,
It must be recognized that the MTD oil and the triorganosiloxy-terminated diorganopolysiloxane plasticizer are necessary components of the present composition. In accordance with the present invention, the RTV silicone rubber composition produced in a static mixer and devolatilization extruder, without plasticizer, produces approximately It also does not have an application rate of 50-150 g or more. To obtain an uncured RTV silicone rubber composition having the above application speed in the uncured state, it is only necessary to produce it by a combination of static mixer and devolatilization extruder as outlined above. In addition, it is necessary to use one or more plasticizers in the preparation of the composition. Thus, in order to obtain favorable application rates, it is desirable to use at least an MTD oil as defined above in the preparation of the composition. In a most preferred embodiment, an MTD oil as defined above and a triorganosiloxy-terminated diorganopolysiloxane polymer also as defined above are used to obtain an uncured RTV silicone rubber composition having an application rate within the preferred ranges noted above. Preference is given to using both in the amounts mentioned above. U.S. Pat. No. 4,395,526 to White et al., U.S. Pat.
No. 4,720,531 as well as the disclosures of other US patents cited herein are specifically incorporated by reference into the application of the present invention. Additionally, it should be noted that the continuous process of the present invention can be used to make any one-component alkoxy-functional RTV composition, such as that disclosed in Bears US Pat. No. 4,100,129. In addition, the method of the present invention eliminates any scavenging, noting that the polymer is first end-capped in a static mixer and then the end-capped polymer is mixed with the other ingredients in a devolatilizing extruder. or a composite crosslinker scavenger. The other ingredients can be any of the ingredients normally associated with one-component RTV compositions. Alternatively, all components can be mixed in a devolatilizing extruder if increased viscosity is not a factor. Regarding the application speed, whether mentioned in the detailed description of the invention or in the claims, the application speed values given in the invention range from 1.030 to
It should be noted that this corresponds to compositions with specific gravity in the range 1.050. Furthermore, the process can be carried out semi-continuously or in batches by first mixing in a static mixer and then after a while in an extruder, but this is generally undesirable. The following examples are provided for the purpose of illustrating the invention and are not intended to limit or delimit the invention. All parts in the examples are by weight. Example 1 Examples 1-5 were conducted solely in a devolatilization extruder. This example, like Examples 2-5, describes the preparation of a continuous composition only in a devolatilizing extruder. The devolatilizing extruder used was a Wernerpfleider twin screw devolatilizing extruder. 17 parts of octamethyltetrasiloxane-treated fumed silica were added continuously to the hopper of the extruder. In the first barrel in the extruder, 100
parts by weight of silanol-terminated dimethylpolysiloxane (having a viscosity in the range of 100,000 to 200,000 centipoise at 25°C), 10 parts by weight of a plasticizer fluid (3 mole percent of trimethylsiloxy monofunctional units,
20 mole percent methylsiloxy trifunctional units,
It has 77 mole percent dimethylsiloxy difunctional units, a viscosity of 50 centipoise at 25°C and a viscosity of 0.5
% silanol) was added. This fluid is hereinafter referred to as "MTD" fluid in the examples. These three components are then further supplemented with 40 parts by weight of trimethylsiloxy-terminated dimethylpolysiloxane (approximately 500 parts per million parts of silanol);
100 centipoise at 25° C.) and 0.2 parts by weight of a polyether sag control agent sold under the name Pluracol V-7 were added to the first barrel of the extruder. To the second barrel of the devolatilizing extruder, 5 parts by weight of methyltrimethoxysilane, 0.33 parts by weight of acetic acid, and 0.67 parts by weight of n-dihexylamine were added sequentially. At barrel 11 or near the end of the devolatilizing extruder, 5 parts by weight of hexamethyldisilazane, 1.7 parts by weight of 3-(2-aminoethylamino)-propyl-trimethoxysilane as an adhesion promoter and 0.33 parts by weight of Dibutyltin diacetate was added. The devolatilizing extruder was maintained at a temperature of about 50°±5°C and the production rate of RTV uncured silicone rubber composition was about 151 pounds per hour. This composition had an application rate of 38 grams per minute. The devolatilizing extruder had 13 separate mixing steps, or compartments, where mixing could occur and components could be added if desired. Example 2 The extruder of Example 1 was operated simultaneously and the same ingredients were added in barrel 1 or step 1 and barrel 11 or step 11. However, in barrel 2 or step 2, instead of the catalyst mixture of Example 1,
6.25 parts by weight methyltrimethoxysilane, 0.41 parts by weight acetic acid and 0.84 parts n-dihexylamine were added in this example. The processing temperature of the extruder is approximately 50°C ± 5°C, and the produced composition is heated at 48°C per minute.
It had an application rate of g. The application rate values obtained in Examples 1 and 2 corresponded to compositions with specific gravity in the range 1.010 to 1.050. Example 3 This method was operated similarly to Example 1 using the same ingredients and the same extruder. The process was operated continuously as in Examples 1 and 2. However, the catalyst composition below was used in place of the catalyst composition of Example 1 and added at barrel 2 or step 2 of the extruder. The types of ingredients and amounts of ingredients added to Barrel 1 and Barrel 11 were the same as in Example 1. The catalyst composition added sequentially to barrel 2 in this example was 7.5 parts by weight methyltrimethoxysilane, 0.5 parts by weight acetic acid, and 1.0 parts by weight n-dihexylamine. The extruder processing temperature was maintained at about 50°C±5°C and the application rate of the uncured composition was about 57 grams per minute for compositions having specific gravity within the range of 1.010 to 1.050. Example 4 This example was run like Examples 1, 2 and 3 only in the devolatilization extruder. The types and amounts of ingredients added to extruder barrels 1 and 11 were the same as in Example 1. The catalyst components added in barrel 2 were different from Example 1 and were 10 parts by weight methyltrimethoxysilane, 0.66 parts by weight acetic acid and 1.34 parts by weight n-dihexylamine. The processing temperature of the extruder was 50°C±5°C and the application rate of the uncured composition produced was 76 g, corresponding to an uncured RTV silicone rubber composition having a specific gravity in the range of 1.010 to 1.050. Example 5 In this example, the composition was prepared by mixing only in a devolatilizing extruder, similar to the four examples above. 17 parts by weight of octamethylcyclotetrasiloxane treated fumed silica was added to the hopper of the extruder. into barrel 1 of the extruder at 25°C.
100 parts by weight of a silanol-terminated dimethylpolysiloxane polymer having a viscosity in the range of 100,000 to 200,000 centipoise was added. Same as Example 1
Also added to barrel 1 were 10 parts "MTD" fluid, 40 parts by weight of the same trimethylsiloxy-terminated dimethylpolysiloxane polymer as Example 1, and 0.2 parts by weight of the polyether of Example 1. In barrel 2,
6.7 parts by weight dimethyltetramethoxysilazane,
0.33 parts acetic acid and 0.67 parts n-dihexylamine were added. To barrel 11, 1.7 parts of 3-(2-aminoethylamino)-propyltrimethoxysilane and 0.6 parts of dibutyltin diacetate were added sequentially. The method was operated continuously. The processing temperature of the composition was maintained at approximately 80°C. The production rate of the composition was 149 pounds per hour. The uncured composition produced by the above method had the following physical properties.

EXAMPLE 6 This example uses both a static mixer and a devolatilizing extruder in processing the composition. The composition was processed continuously. at 25°C as per above
100 parts by weight of a silanol-terminated dimethylpolysiloxane polymer having a viscosity in the range of 100,000 to 200,000 centipoise, 1.05 parts by weight of methyltrimethoxysilane, 0.21 parts by weight of n-dihexylamine and 0.05 parts by weight of acetic acid in a static mixer. mixed continuously. The temperature of the static mixer was controlled at 60°C±5°C. The end-capping reaction was allowed to proceed for 1 hour, at which time the presence of remaining silanol groups was determined by infrared spectroscopy. Then 0.5 parts by weight of hexamethylsilazane was added to scavenge free methanol in the polymer. The methyldimethoxy end-capped polymer was stored in a closed container at room temperature for approximately one week before being mixed in an extruder. The pre-endcapped polyalkoxy-terminated dimethylpolysiloxane polymer was pumped into barrel 1 of the Werner Preider devolatilizing extruder at the end of storage. Add 17 parts by weight of octamethylcyclotetrasiloxane-treated fumed silica to the hopper, then add to barrel 1 100 parts by weight of pre-endcapped dimethylpolysiloxane polymer, 10 parts by weight of the "MTD" fluid of Example 1, 20 parts by weight. treated fumed silica and 0.2 parts by weight polyether (this was manufactured by Union Carbide Corporation as UCON LB-1145)
As mentioned above,
added continuously. Continuously add 3.7 parts by weight of hexamethyldisilazane to barrel 7 of the extruder,
0.7 parts by weight of methyltrimethoxysilane, 1.47 parts by weight of aminoethylaminopropyltrimethoxysilane and 0.9 parts by weight of dibutyltin diacetate were added sequentially to barrel 11 of the extruder. The extruder processing temperature was maintained at 50°C ± 5°C and the uncured material production rate was 150 pounds per hour. The physical data of the uncured mixed composition is as shown in the table below.

[Table] Example 7 An uncured RTV composition was produced continuously in the same manner as in Example 6. Mixing was carried out continuously in a static mixer and in a devolatilization extruder. at 25℃
A 100,000-200,000 centipoise methyldimethoxy end-capped dimethylpolysiloxane polymer was prepared in a static mixer as described in Example 6. The polymer was continuously pumped into a devolatilizing extruder and mixed with other ingredients as follows. 17 parts by weight of octamethylcyclotetrasiloxane treated fumed silica was continuously added to the devolatilization extruder hopper. In barrel 1 of the extruder,
100 parts by weight of end-capped dimethylpolysiloxane polymer, 10 parts by weight of the "MTD" fluid of Example 1,
40 parts by weight of the trimethylsiloxy end-capped dimethylpolysiloxane polymer of Example 1 and 0.2 parts by weight of the polyether sag control agent of Example 6 were added. In barrel 11, 3.68 parts by weight hexamethyldisilazane, 0.74 parts by weight methyltrimethoxysilane, 1.47 parts by weight 3-(2-aminoethylamino)
-Propyltrimethoxysilane and 0.19 parts of dibutyltin diacetate were added successively. The extruder processing temperature was maintained at approximately 50°C ± 5°C, and the extruder production rate was 150 pounds per hour. The physical data of the fully cured compositions produced continuously by the above method are shown in the table below.

【table】

EXAMPLE 8 The following example illustrates a preferred endcapping reaction for use in the present invention. However, a devolatilizing extruder and continuous mixing were not used in these two examples. These examples, within the scope of the invention, include:
The preferred endcapping reactions used and required for the continuous process are merely disclosed and described below. 100 parts by weight of polyalkoxy-terminated dimethylpolysiloxane with a viscosity of approximately 3000 centipoise at 25°C.
4.5 parts of methyltrimethoxysilane, 0-0.2 parts of acetic acid and 0-0.5 parts of n-dihexylamine were mixed. Mixing was carried out at 80°C for 15 minutes. The extent of end-blocking was determined by infrared. The results are stated in the table below.

Table: Example 9 A silanol-terminated dimethylpolysiloxane polymer having a viscosity of approximately 120,000 centipoise at 25° C. is added to a suitable mixer equipped with a vacuum system and nitrogen purification equipment.
100 parts 17 parts octamethyltetrasiloxane-treated fumed silica, 35 parts silanol-containing trimethylsiloxy-terminated dimethylpolysiloxane fluid, 15 parts silanol-containing "MTD" fluid of Example 1, and 0.2 parts polyether (union carbide).・By Corporation
(sold under the product name UCON LB-1145).
The mixture was stirred at room temperature for 2 hours under full vacuum of about 20 mmHg to obtain the RTV base. To 100 parts of this base preheated at 80°C are added 4.0 parts of methyltrimethoxysiloxane, 0.2 parts of acetic acid and 0.4 parts of n-dihexylamine, then semkit
(Semkit) mixer for 15 minutes.
A solution consisting of 0.1 parts of 3-(2-aminoethylamino)-propyltrimethoxysilane, 2.0 parts by weight of hexamethyldisilazane and 0.2 parts of dibutyltin diacetate is added to the above mixture, then a second
Mixing was carried out for 15 minutes. Following mixing, RTV
The composition was placed in a sealed aluminum tube and stored for 24 hours at room temperature and 24 hours at 100°C. After aging, the material was pressed into ASTM sheets and cured for 3 days at room temperature and 50% relative humidity. After curing, the physical properties were measured and the results are shown in the table.

Table: Example 10 In a suitable mixer equipped with a vacuum system and nitrogen purification, 100 parts of a silanol-terminated dimethylpolysiloxane polymer having a viscosity of 120,000 centipoise at 25°C, 17 parts of the treated fumed silica of Example 9,
20 parts of the silanol-containing trimethylsiloxy-terminated dimethylpolysiloxane polymer of Example 1, 10 parts of the silanol-containing "MTD" fluid of Example 1, and 0.2 parts of the polyether of Example 10 were charged. The mixture was stirred at room temperature under full vacuum (20 mmHg) for 2 hours to obtain the RTV base. The composition was mixed using a Semkit mixer in two steps as follows. First, by mixing for 15 minutes, 2.5 to 4.5 parts of methyltrimethoxysilane as shown in the table below and acetic acid were added to 100 parts of the base prepared as above.
0.13 parts and 0.33 parts of n-dihexylamine were added. This mixture was mixed at 80°C for 15 minutes, then the second
Hexamethyldisilazane with a 15 minute mixing step of
2.7 parts of the adhesion promoter of Example 9 and 0.33 parts of dibutyltin diacetate were mixed. Following mixing, the RTV composition was placed in a sealed aluminum tube;
Stored at room temperature for 24 hours and at 100°C for 48 hours. After aging, the material was pressed into ASTM sheets and cured for 3 days at room temperature and 50% relative humidity. Physical properties were then measured and the results are shown in the table below.

【table】

EXAMPLE 11 Various compositions were prepared using the base composition described in Example 8 by mixing in two steps in a Semkit mixer and mixing as follows.
The base of Example 1 in the mixer during a 15 minute mixing period.
100 parts, 3.0 to 4.5 parts of methyltrimethoxysilane shown in the table below, 0.1 to 0.25 parts of acetic acid shown in the table below, and 0.5 parts of n-dihexylamine.
parts were mixed. In the second mixing step, 2 to 3 parts of dimethyltetramethoxydisilazane and 0.4 parts of dibutyltin diacetate as shown in the table below.
Parts by weight were mixed. This was combined with the adhesion promoter of Example 9.
The tack-free time was measured after 24 hours at room temperature, 24 hours at 100°C, and 48 hours at 100°C after addition of 1.0 part.
The aging results are shown in the table below.

【table】

Claims (1)

[Scope of Claims] 1 (a) an organopolysiloxane in which the silicon atom at the end of each polymer chain is terminated with a hydroxy group, (b) a polyalkoxy crosslinking agent, (c) containing acetic acid and n-hexylamine an endcapping catalyst system, (d) an effective amount of a condensation catalyst, and (e) an effective amount of a scavenger to bind hydroxyl groups in a devolatilizing extruder. A stable, non-stick elastomer that can be converted into a long-term stable, tack-free elastomer under dry ambient conditions.
A method for continuously producing a substantially anhydrous and substantially acid-free room temperature curable organopolysiloxane composition in one package. 2 The scavenger for hydroxy functional groups has the formula Acyclic silyl nitrogen scavenger and formula having at least one or all units of, when present, the formula [In the above three formulas, R ¹⁰ is alkyl,
A C _1-8 aliphatic organic group or aryl group selected from the group consisting of alkyl ether, alkyl ester, alkyl ketone, and alkyl cyano, and R ¹¹ is a C _1-8 monovalent substituted or unsubstituted is a hydrocarbon group, Q is hydrogen, a C _1-8 monovalent substituted or unsubstituted hydrocarbon group and the formula (where R ¹⁰ and R ¹¹ are as defined above), a varies from 0 to 2,
f varies from 0 to 3, h is 0 or 1, s is an integer varying from 1 to 25, d is an integer varying from 1 to 25, ^R22 is hydrogen and _C1-8 and R ²³ is independently selected from monovalent hydrocarbons and hydrocarbonoxy groups, and A is hydrogen and C _1-8
a monovalent substituted or unsubstituted hydrocarbon and the formula (wherein R ¹⁰ and R ¹¹ are as defined above, g varies from 0 to 3, and the scavenger has at least one hydrocarbonoxy group in its molecule) R ¹² is defined identically to R ¹⁰ and R ¹³
and R ¹⁴ is defined ^{the same as R 11 .} 3 formulas (wherein 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 teeth
2. The method of claim 1, comprising an effective amount of a crosslinking silane (C _1-13 monovalent substituted or unsubstituted hydrocarbon group, and b is an integer of 0 or 1). 4 The stabilizing amount of scavenger for the hydroxy functional group is represented by the formula (a) (wherein Y is selected from R″ and R ₂ N)
and (b) a silicon nitrogen compound having the formula (1) 3 to 100 mole percent of chemically bonded structural units selected from the group consisting of units having
and (2) a silicon-nitrogen polymer containing 0 to 97 mole percent of chemically bonded structural units represented by the formula (R) _c SiO _4-c/2 (silicon atoms in the silicon-nitrogen polymer are
The free valences of said silicon atoms, which are bonded to each other by means of members selected from SiOSi bonds and SiNR''Si bonds, other than those bonded to oxygen forming siloxy units and nitrogen forming silazi units, are ( R'') ₂ is bonded to a member selected from N and R groups, and the R to the silicon atom of the silicon-nitrogen polymer
The ratio of the total number of groups and said (R″) ₂ N groups has a value from 1.5 to 3, where R″ is a member selected from the group consisting of hydrogen, a monovalent hydrocarbon group and a fluoroalkyl group. , R is hydrogen,
a member selected from the group consisting of a monovalent hydrocarbon group and a fluoroalkyl group, and c
2. The method of claim 1, wherein the silicon-nitrogen compound is a silicon-nitrogen compound selected from the group consisting of: 5 The stabilizing amount of scavenger for hydroxy functional groups is expressed by the formula (In the formula, R″ is a group selected from the group consisting of hydrogen and a C _1-8 monovalent hydrocarbon group, and R ²⁰ is
selected from C _1-8 monovalent hydrocarbon groups, C _1-8 alkoxy groups and fluoroalkyl groups, where g is 1 to 3
and h is an integer varying from 0 to 2, and the total number of h+g does not exceed 3).
The method described in section. 6 The silazane compound has the formula Claim 4, wherein R'' and R are selected from the group consisting of hydrogen, monovalent hydrocarbon groups and fluoroalkyl groups, and n is an integer from 0 to 20. The method of 7. The silazane compound has the formula (wherein R'' and R are selected from the group consisting of hydrogen, a monovalent hydrocarbon group, and a fluoroalkyl group, and n is an integer from 0 to 20). The method of paragraph 4. 8 (1)(a) an organopolysiloxane in which the silicon atom at each polymer chain end is terminated with a hydroxy group, (b) a polyalkoxy crosslinker or composite crosslinker scavenger, and ( c) pass an end-capping catalyst system containing acetic acid and n-hexylamine through a static mixer to produce a polyalkoxy-terminated diorganopolysiloxane, and (2) devolatilize the polyalkoxy-terminated diorganopolysinoxane. A stable, one-pack cage capable of being converted into a long-term stable, tack-free elastomer under ambient conditions substantially free of moisture, characterized in that it is introduced into an extruder and mixed therein with a condensation catalyst. 9. A continuous process for producing a substantially anhydrous, room temperature curable organopolysiloxane composition of 9. Claim 8, wherein the latter polyalkoxy crosslinker is also a scavenger for hydroxyl groups.
The method described in section.