JPH0219139B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composition that generates hydrogen gas at room temperature to form an elastic polyorganosiloxane foam, and particularly relates to a polydiorganosiloxane composition that has a sufficient and appropriate pot life and is capable of forming an elastic foam with a desired expansion ratio. The present invention relates to siloxane compositions. Polyorganosiloxane foam takes advantage of its properties such as heat resistance, low-temperature flexibility, ozone resistance, UV resistance, and light weight, and is used as a heat-resistant, shock-absorbing material, heat-resistant insulation material, and heat-resistant material. Used in a wide range of applications such as gaskets. Furthermore, in recent years, with the demand for insulation in buildings, it can be used as an insulation filler and sealant for gaps in building walls, taking advantage of its excellent weather resistance, heat resistance, cold resistance, and extremely low compression set rate. In this type of application, a foam-forming material having a pot life of at least 5 minutes, preferably about 10 to 20 minutes, is required because construction is performed on site. A technique that can be used to generate hydrogen gas and form a polyorganosiloxane foam is the method described in Japanese Patent Publication No. 11839/1983.
This method uses as active ingredients a silicon compound having an aminoxy group bonded to a silicon atom, a polydiorganosiloxane whose terminal end is blocked with a silanol group, and a silicon compound containing a silicon-hydrogen bond. Hydrogen gas generated when hydroxylamine produced by a curing reaction between the polydiorganosiloxane and the silanol group-terminated polydiorganosiloxane reacts with the silicon-hydrogen bond is utilized. In this method, foam formation is started by mixing the three active ingredients mentioned above, but the time from mixing to the start of foaming and thickening, that is, pot life, can be obtained as long as necessary for the construction work. If this is the case, the foaming reaction will pass its peak before the foaming reaction reaches a hardening state sufficient to exhibit the foam-break prevention effect, so there is a problem that the required foaming ratio cannot be obtained; If the curing is accelerated until the foam-breaking effect is exerted before the foaming reaction reaches its peak in order to increase the temperature, there is a problem that foaming and thickening will begin during mixing or operation. Therefore, it has no choice but to be used with a pot life of about 1 to 2 minutes at most.
Moreover, the resulting foam had insufficient physical properties such as expansion ratio. In addition, in order to prevent the bubbles generated by hydrogen generation from bursting during polyorganosiloxane foam formation, it is important that the composition has a certain degree of viscosity to exhibit the foam-rupturing prevention effect. That is, unless the speed of foaming and thickening and curing proceed in a well-balanced manner, it is difficult to obtain a foam having the required expansion ratio.
In this regard, in the case of the prior art described above, at the initial stage of foaming, the viscosity of the composition is not high enough to effectively exhibit the foam-rupturing prevention effect, and foams burst, resulting in the formation of a foam with a low expansion ratio. This was one of the causes. The present invention has been made in order to overcome the drawbacks of conventional organosiloxane foams as described above. That is, an object of the present invention is to provide a polyorganosiloxane composition that forms an elastic foam at room temperature and has a suitable pot life necessary for construction work. Another object of the present invention is to provide a polyorganosiloxane composition that exhibits an appropriate foam-breaking prevention effect from the early stage of the foaming reaction, and that allows foaming, thickening, and curing to proceed in a well-balanced manner to obtain an elastic foam with a high expansion ratio. Our goal is to provide the following. That is, the present invention comprises: (A) 100 parts by weight of a polydiorganosiloxane whose ends are blocked with silanol groups and whose viscosity at 25°C is 500 to 200,000 cst; (B) an average number of more than two silicon atoms in the molecule; 0.1 to 50 parts by weight of an aminoxy group-containing organosilicon compound having a bonded organoaminoxy group; from 0.1 to 50 parts by weight of a silicon-hydrogen bond-containing polyorganosiloxane present in an amount of 10% or more, (D) from 1 to 30 parts by weight of fumed silica, and (E) from 0.005 to 10 parts by weight of an isocyanato group-containing organic compound. A polyorganosiloxane composition that forms an elastic foam at room temperature. The siloxane composition of the present invention has a pot life of about 5 minutes or more, and foaming and thickening are suppressed during mixing and construction work during that time, so it has excellent workability. The pot life can be adjusted depending on the application by changing the components and blending ratio of the composition, and it is easy to set the pot life to the generally preferred pot life of 10 to 20 minutes. Foaming begins only after the work is completed, but the foaming prevention effect is properly demonstrated from the beginning of foaming, and then foaming, thickening, and hardening proceed in a well-balanced manner, resulting in a high foaming ratio of approximately 3 times or more, resulting in foam regulating properties. A good elastic form is obtained. Component (A) used in the present invention is a silanol group-terminated polydiorganosiloxane used in a condensed polysiloxane composition that can be cured at room temperature, and has an effect on foaming, improving the mixability of the composition before curing, and preventing foam breakage. For the purpose of obtaining the physical properties of the formed elastic foam, the viscosity at 25° C. must be in the range of 500 to 200,000 cst, preferably in the range of 1,000 to 50,000 cst. If the viscosity is lower than 500 cst, the flexibility of the siloxane foam will not be obtained, and the foam prevention effect will be incomplete;
This is because if it is higher than 200,000 cst, the mixability and workability during use will deteriorate. Examples of organic groups directly bonded to the silicon atom of this silanol-terminated polydiorganosiloxane include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and octyl groups, vinyl groups, and allyl groups. alkenyl groups such as
Aryl groups such as phenyl groups, aralkyl groups such as β-phenylethyl groups, and 3,3,3
-trifluoropropyl group, chloromethyl group, β
Examples include monovalent substituted hydrocarbon groups such as a cyanoethyl group, but monovalent hydrocarbon groups such as a methyl group, vinyl group, or phenyl group are generally advantageous due to ease of synthesis. be. Among them, the methyl group not only provides the easiest raw material intermediate, but also provides the lowest viscosity relative to the degree of polymerization of the siloxane, favoring the balance between the workability of the composition before curing and the physical properties of the elastic foam after curing. Therefore, it is preferable that 85% or more of all organic groups are methyl groups, and it is more preferable that substantially all organic groups are methyl groups. However, if the elastic foam after curing requires cold resistance or heat resistance, it is recommended to use phenyl groups as part of the organic groups. The aminoxy group-containing organosilicon compound as the component (B) used in the present invention is produced by dehydroxylamine reaction with the terminal silanol group of the silanol group-terminated polydiorganosiloxane as the component (A). It crosslinks and extends the chain length of the polydiorganosiloxane and at the same time supplies hydroxylamine necessary for the foaming reaction, and may be a silane derivative or a linear, cyclic or branched siloxane derivative. The number of aminoxy groups must be more than two on average in the molecule in order to at least extend the chain and simultaneously crosslink. When it is desired to obtain a composition that provides a rigid elastic foam, it is preferable to use 3, 4 or more such molecule present in the molecule. The organic groups to be bonded to the aminoxy group include two monovalent hydrocarbon groups such as methyl, ethyl, propyl, butyl, and cyclohexyl groups, or two divalent hydrocarbon groups such as butylene and amylene groups. Although one is exemplified, an ethyl group is preferred from the viewpoint of easy availability of raw materials, ease of synthesis, reactivity, and ease of volatilization of organohydroxylamine to be released. Examples of such aminoxy group-containing organosilicon compounds include the following. Note that, for the sake of simplicity, the following abbreviations will be used for various organosilicon compounds. (Abbreviation) Me: Methyl group, Et: Ethyl group, Bu: Butyl group, Vi: Vinyl group, Ph: Phenyl group Si(ONEt ₂ ) ₄ , MeSi(ONEt ₂ ) ₃ , PhSi
(ONMe ₂ ) ₃ , PhSi(ONEt ₂ ) ₃ ,

[Formula] Et ₂ NOMe ₂ SiSiMe ₂ ONEt ₂ ,
Et ₂ NOMe ₂ SiOSiMe ₂ ONEt ₂ ,

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

[Formula] The amount of such an aminoxy group-containing organosilicon compound added is selected from the range of 0.1 to 50 parts by weight, preferably 1 to 30 parts by weight, based on 100 parts by weight of component (A). In this dehydroxylamine reaction, when the amount of aminoxy groups in component (B) is smaller than the silanol groups in component (A), the polycondensation reaction of the following formula proceeds quickly and the curing rate becomes faster. (In the formula, R represents a monovalent hydrocarbon group, m is 2
(In the above, n represents an integer of 1 or more.) On the other hand, when there are more aminoxy groups than silanol groups, the reaction of the following formula occurs first preferentially. (In the formula, R, m and n are the same as above) Next, this polydiaminoxysiloxane

[Formula] absorbs moisture in the atmosphere, undergoes polycondensation as shown in the formula below, and gradually hardens. For this reason, if the amount of the aminoxy group-containing organosilicon compound added is less than 0.1 part by weight, not only will the curing speed due to the reaction with the silanol group-terminated polydiorganosiloxane become faster and sufficient working time will not be obtained. The foaming ratio will also be low. Furthermore, if the amount added exceeds 50 parts by weight, not only will the curing speed be significantly delayed and the curability will be reduced, but also the foam that has grown will be crushed as the anti-foaming effect is delayed. The desired foaming ratio cannot be obtained, and the foam regulating properties are also poor. The silicon-hydrogen bond-containing polyorganosiloxane (C) reacts with organohydroxylamine, which is a reaction product of components (A) and (B), to generate hydrogen gas, and the foaming power of the hydrogen gas Therefore, it contributes to foam formation. In order to obtain the required expansion ratio, it is necessary that an average of 10% or more of all the silicon atoms contained in the molecule, preferably 25 to 100%, have silicon-hydrogen bonds, and that they are parallel to the expansion. For the purpose of causing thickening and curing reactions, and finally forming an elastic foam cured product,
It is necessary that the molecule contains more than two silicon-hydrogen bonds on average. When it is desired to obtain an elastic foam with a high expansion ratio, it is advantageous to use a siloxane having a high proportion of silicon atoms having silicon-hydrogen bonds and a large number of silicon atoms in the molecule.
In other words, by using a polyvalent hydrogen-silicon bond-containing siloxane having three, four, or more hydrogen-silicon bonds in the molecule, the viscosity quickly increases at the same time as foaming starts, resulting in excellent foam breakage. It becomes possible to exhibit the prevention effect, and it is possible to form an elastic foam that has good foam regulating properties, is relatively hard, and has an extremely small compression set ratio. Such a silicon-hydrogen bond-containing organosiloxane is a polymer consisting of a silicon-hydrogen bond-containing siloxane unit, or a polymer consisting of a silicon-hydrogen bond-containing siloxane unit, or the unit and, if necessary, a triorganosiloxane unit, a diorganosiloxane unit, a monoorganosiloxane unit, and/or
It is a copolymer with SiO ₂ units, and can be chained, branched,
It may be either ring-shaped or net-shaped. Examples of organic groups directly bonded to silicon atoms include alkyl groups such as methyl, ethyl, propyl and hexyl groups, aryl groups such as phenyl, 3,3,3
Examples include monovalent substituted hydrocarbon groups such as -trifluoropropyl group and chloromethyl group,
A monovalent hydrocarbon group such as a methyl group or a phenyl group is generally advantageous for ease of synthesis. Among them, it is preferable that 85% or more of all organic groups are methyl groups, not only because raw material intermediates can be obtained most easily, but also from the consideration of miscibility with component (A). More preferably, it is a methyl group. The amount of component (C) is (A) component.
It is necessary that the amount is 0.1 to 50 parts by weight, preferably 1 to 30 parts by weight, per 100 parts by weight. (C) component
If it is less than 0.1 parts by weight, the foaming power will be poor and the required foaming ratio will not be obtained, and if it exceeds 50 parts by weight, the effect of preventing foam breakage will be delayed, especially in deep areas, resulting in poor foam regulation in those areas. Undesirable. The fumed silica, which is component (D) of the present invention, is a particularly characteristic component in the present invention, and contributes to increasing the apparent viscosity of the system, especially at the beginning of foaming, thereby exerting the effect of preventing foam breakage. It is something. As a result, the foam has a high expansion ratio and good foam control properties. Component (D) also plays a role in appropriately adjusting the fluidity of the composition. Component (D) may be the same as fumed silica commonly used as a reinforcing filler for silicone elastomers, and is generally obtained by firing silicon tetrachloride or organochlorosilane. These fumed silicas may be untreated or may be surface-treated with hexaorganodisiloxane, octamethylcyclotetrasiloxane, organochlorosilane, hexamethyldisilazane, or the like. Other fine inorganic powders commonly used as fillers in silicone rubber, namely precipitated silica, silica aerogel, ground silica,
Diatomaceous earth, calcium carbonate, and the like do not have the above-mentioned excellent foam-forming ability. The amount of component (D) used must be in the range of 1 to 30 parts by weight, and preferably in the range of 3 to 15 parts by weight, per 100 parts by weight of component (A). If the amount of component (D) is less than this, sufficient foam-breaking prevention effect will not be exhibited.
If the amount is more than this, it will not only be difficult to obtain a uniform composition, but also the viscosity of the composition will increase, resulting in a decrease in workability. The isocyanato group-containing organic compound, which is the component (E) of the present invention, suppresses the immediate start of foaming when mixing the components (A) to (D) in the composition of the present invention. It is an essential ingredient for imparting the required pot life to the composition. The foaming suppressing effect of component (E) is achieved by preferentially performing the following reaction before the organohydroxylamine generated by the curing reaction between component (A) and component (B) reacts with component (C). The organohydroxylamine was removed from the curing composition, and the organohydroxylamine and (C)
It is presumed that this is brought about by suppressing the generation of hydrogen gas due to reactions with components. (However, in the formula, R and R' represent hydrocarbon groups.) When most of the component (B) is lost during this reaction, the reaction between the hydroxylamine and the component (C) then begins and foaming occurs. Start. Furthermore, the foam-breaking prevention effect due to the interaction of component (D) with components (A) and (B) also begins to be expressed after component (E) is consumed. The amount of component (E) to be used is selected within the range of 0.005 to 10 parts by weight per 100 parts by weight of component (A).
Although it is possible to impart the required pot life to the composition, it is preferably selected in the range of 0.01 to 5 parts by weight. If the amount of component (E) is less than this, not only will foaming start during mixing or operation, but the pot life will be shortened due to the effect of preventing foam breakage due to thickening. If the amount is higher than this, a considerable portion of the organohydroxylamine produced by the reaction between components (A) and (B) will react with component (E) and be lost, resulting in the absolute If the amount is insufficient, a sufficient foaming ratio cannot be obtained. Component (E) used in the present invention includes:

【formula】

【formula】

[Formula] OCN−(CH ₂ ) ₆ − NCO,

【formula】 【formula】

【formula】

【formula】

【formula】

Monomers with isocyanato groups such as [Formula], adduct bodies, such as (However, in the formula, m indicates a number from 0 to 100) multimers such as (However, in the formula, p indicates a number from 3 to 50.) Urethane polymers such as Me ₃ SiNCO, Me ₂ Si(NCO) ₂ , PhSi(NCO) ₃ ,

【formula】

Examples include organosilicon compounds such as. The composition of the present invention is usually stored separately in two containers: a part consisting of (A), (C) and (D), and a part consisting of (B) and (E), and when used, both are separated. It is used as a two-pack type that foams and hardens by mixing. The composition of the present invention may contain an inorganic filler for the purpose of appropriately adjusting reinforcing properties and fluidity. These inorganic fillers include crushed quartz, diatomaceous earth, calcium carbonate, talc,
Examples include clay, calcined clay, and alumina. Further, in order to impart self-extinguishing properties, it is preferable to add platinum or a platinum-based compound such as chloroplatinic acid. In this case, it is advantageous to use aluminum hydroxide as a filler, and a polyorganosiloxane whose terminal end is blocked with a triorganosilyl group and has a phenyl group may also be used, or component (A) having a phenyl group or ( Self-extinguishing properties can be enhanced by using component C) or by using carbon black in combination. When a polyorganosiloxane whose ends are blocked with silanol groups and contains phenyl groups is used as component (A), it is preferable that 0.1 to 25 mol % of the organic groups in the polyorganosiloxane are phenyl groups. If the amount of phenyl group is less than 0.1 mol%, there is no effect of improving self-extinguishing property, and if it exceeds 25 mol%, the viscosity of (A), This is because, as a result, the apparent viscosity of the uncured composition has to be significantly increased, which impairs workability. Since the composition of the present invention can provide the required pot life, it is suitable for applications that require time to work, such as insulation filling and sealing of joints in external walls of buildings. The present invention will be specifically explained below using examples.
In the examples, all parts indicate parts by weight. Example 1 10 parts of silanol-terminated polydimethylsiloxane having a viscosity of 27,000 cst at 25°C was kneaded with 10 parts of fumed silica to form a base compound C-
I got 1. Also, the same polydimethylsiloxane
75 parts of calcium carbonate with an average particle size of 0.5μ in 100 parts, 100 parts of crushed quartz with an average particle size of 1.2μ, or wet silica
Mix 15 parts each to make base compound C.
-2, C-3, and C-4 were obtained. Next, 100 parts each of these base compounds C-1 to C-4 were uniformly mixed with a silicon-hydrogen bond-containing polyorganosiloxane, an aminoxy group-containing silicon compound, and an isocyanate group-containing compound shown in Table 1 to prepare a sample. 100-111 were prepared. However, the sample
100~103 is C-2~C as the base compound
Samples 100 and 104 are comparative examples in which Samples 100 and 104 were not added with an isocyanate group-containing compound. Each sample thus obtained was immediately poured into a polypropylene cylindrical container with a bottom diameter of 5 cm, and the pot life (time from mixing to the start of foaming and thickening), final foaming ratio,
The foam regulating property and the quality of skin formation on the surface layer were observed. The results are also shown in Table 1. The mixing and foaming were performed in an atmosphere of 23°C and relative humidity of 60%.

【table】

[Table] Example 2 Polydiorganosiloxane whose ends are blocked with silanol groups, 5 mol% of all bifunctional siloxy units are diphenylsiloxy units, and the remainder is dimethylsiloxy units, and has a viscosity of 12,000 cst at 25°C.
A base compound was obtained by mixing 100 parts of fumed silica, 7.5 parts of fumed silica, and 75 parts of aluminum hydroxide fine powder with an average particle size of 1.6 μm. Samples 20 to 25 were prepared by mixing 100 parts of the base compound thus obtained with a silicon-hydrogen bond-containing polyorganosiloxane, an aminoxy group-containing silicon compound, and an isocyanate group-containing compound shown in Table 2. However, Sample 20 is a comparative example in which no isocyanate group-containing compound is added. The foaming start time and final foaming ratio were measured in the same manner as in Example 1, and the quality of foam regulating property and skin formation on the surface layer was observed. The results are shown in Table 2. In addition, a chloroplatinic acid aqueous solution corresponding to 0.00005 parts by weight of platinum was added to and mixed with Samples 21 to 25 in Table 2 to prepare Samples 21' to 25', respectively. The elastic foam obtained by foaming and curing these
Cut out a strip of 12.5 mm and approximately 2 mm thick, and place it 1 cm directly above the center of a 2 cm long methane gas combustion flame.
After being placed for 10 seconds, the sample was removed from the flame, and the time from when it was removed from the flame until the shine of the sample disappeared (first self-extinguishing time) was measured. The results are shown in Table 3. The second self-extinguishing time in the table is the one that was measured in the same manner as the first time after the first time was extinguished, the sample was placed in the flame again for 10 seconds, and then removed from the flame.

【table】

【table】

[Table] Example 3 Elastic foams obtained by foaming and curing Samples 13, 15, and 17 prepared in Example 1 were cured at room temperature for 7 days, and then cut into a prismatic shape of 12 x 12 x 50 mm.
The prismatic elastic foam obtained in this way was then molded into a silicone ring material Tosseal 371 manufactured by Toshiba Silicone Corporation.
-C was used to sandwich and paste the sample between two glass plates of 50 x 50 mm and 5 mm thickness to create the test specimen shown in FIG. 1. In the figure, 1 is the above-mentioned glass plate, 2 is Tosseal 371-C, and 3 is a test piece of the above-mentioned elastic foam. After curing the test specimens at room temperature for 7 days, they were installed in a cyclic fatigue tester and subjected to ±20% joint width expansion and contraction 10,000 times, but no abnormalities such as cracks occurred in any of the elastic forms. (Compliant with JISA5758). Example 4 Samples 13, 15, 17, prepared in Examples 1 and 2
Immediately after mixing 23 and 25, 15×15mm, 100mm
It was filled into a U-shaped aluminum groove made of secondary electrolytically colored aluminum, which had been previously coated with Primer ME120 (manufactured by Toshiba Silicone Co., Ltd.) and dried, and foamed and hardened. After curing for 7 days at room temperature, we observed the adhesion of the elastic foam to the aluminum material. All samples showed good adhesion, and when we tried to forcefully remove it, the elastic foam part Cohesive failure occurred. Example 5 100 parts of silanol-terminated polydimethylsiloxane having a viscosity of 4500 cst at 25°C was mixed with fumed silica surface-treated with hexamethyldisilazane.
10 parts, 50 parts of stearic acid-treated colloidal calcium carbonate with an average particle size of 0.6μ, and

A compound having thixotropic properties was obtained by mixing 7.5 parts of organosiloxane represented by the formula. For 100 parts of the compound thus obtained, 10% by weight is added in advance.
of OCN(−CH ₂ )− ₆ NCO added

After adding and mixing 7 parts of [Formula] and stirring for 5 minutes, immediately as shown in Figure 2,
Primer manufactured by Toshiba Silicone Co., Ltd.
YP7502 was applied and dried to fill the vertical joints 21 of ALC (light and heavy foamed concrete) and finished. 22 is a backup material made of foamed polyethylene, and 23 is a filled composition. Construction took approximately 3 minutes, and foaming began approximately 10 minutes after construction was completed. Workability was good, and no slump was observed at any time during construction, after construction, during foaming, or after curing. As a result of disassembling and observing the sample joint on the fourth day after construction,
The expansion ratio was about 3 times, and the adhesiveness to ALC was also good. In addition, the mixed construction atmosphere has a temperature of 23
℃ and relative humidity 62%.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the test specimen for cyclic fatigue testing used in Example 3, and FIG. 2 is a horizontal sectional view showing the filling state of the ALC vertical joints used in Example 5. 1...Glass, 2...Toss seal 371, 3...
Sample (elastic foam), 21...ALC, 22...
Foamed polyethylene backup material, 23...sample (before foaming and curing).

Claims (1)

[Scope of Claims] 1 (A) 100 parts by weight of a polydiorganosiloxane whose ends are blocked with silanol groups and whose viscosity at 25°C is 500 to 200,000 cst; (B) an average number of more than 2 silicon atoms in the molecule; 0.1 to 50 parts by weight of an aminoxy group-containing organosilicon compound having an organoaminoxy group bonded to an atom, (C) having an average number of more than two silicon-hydrogen bonds in the molecule, and the silicon-hydrogen bonds 0.1 to 50 parts by weight of a silicon-hydrogen bond-containing polyorganosiloxane present at 10% or more based on the number of atoms, (D) 1 to 30 parts by weight of fumed silica, and (E) 0.005 to 10 parts by weight of an isocyanato group-containing organic compound. 1. A polyorganosiloxane composition which forms an elastic foam at room temperature, comprising parts by weight. 2. The composition according to claim 1, wherein (A) has a viscosity of 1,000 to 50,000 cst at 25°C. 3. The composition according to claim 1, wherein 85% or more of the organic groups in (A) are methyl groups. 4. The composition according to claim 3, wherein all of the organic groups in (A) are methyl groups. 5. The composition according to claim 1, wherein the organoaminoxy group in (B) is a diethylaminoxy group. 6. The composition according to claim 1, wherein the amount of (B) is 1 to 30 parts by weight per 100 parts by weight of (A). 7. The composition according to claim 1, wherein the organic group in (C) is a methyl group. 8. The composition according to claim 1, wherein the amount of (C) is 1 to 30 parts by weight per 100 parts by weight of (A). 9. The composition according to claim 1, wherein the amount of (D) is 3 to 15 parts by weight per 100 parts by weight of (A). 10. The composition according to claim 1, wherein the amount of (E) is 0.01 to 5 parts by weight per 100 parts by weight of (A). 11. The composition according to claim 1, further comprising platinum or a platinum compound. 12. The composition according to claim 11, wherein 0.1 to 25 mol% of the organic groups in (A) are phenyl groups.