JPH0317871B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to improving the curability of a sealant at low temperatures, and more particularly to a method for improving the curability of a sealant crosslinked with an aminoxy group-containing organosilicon compound at low temperatures. [Technical background of the invention and its problems] A polyorganosiloxane composition that cures at room temperature to become a rubber-like elastic body has excellent heat resistance, cold resistance, and weather resistance, has little change in physical properties due to temperature, and has ozone resistance. , due to its low deterioration due to ultraviolet rays,
Widely used as a building sealant. In particular, the rubber-like elastic material obtained by crosslinking polydiorganosiloxane whose ends are blocked with silanol groups with an organosilicon compound containing an aminoxy group and curing at room temperature has a low modulus, which prevents the deformation of buildings. Because it can absorb stress caused by expansion and contraction due to temperature, it is becoming increasingly important as a sealing material between the outer walls of buildings, mainly high-rise buildings. The width of the joints between the outer walls of these buildings expands and contracts depending on the daily temperature range, so the joint sealing materials used there are required to quickly harden and exhibit rubber elasticity after being cast. required. In this case, the above-mentioned type of sealant that is cross-linked with an aminoxy group-containing organosilicon compound is used in areas where there is a large temperature range between the joint widths due to its excellent mechanical properties, but it Since the speed of this type of crosslinking reaction is extremely slow, under such conditions the joints undergo deformation before rubber elasticity is developed, causing the problem of constrictions and cracks in the sealant. To address this problem, a crosslinking reaction is applied to sealants in which the base compound component, which basically consists of a polyorganosiloxane base polymer, a filler, and optionally additives, and the aminoxy group-containing organosilicon compound are packaged separately. For the purpose of promoting crosslinking, attempts have been made to reduce the amount of the aminoxy group-containing organosilicon compound used as a crosslinking agent, and to add an appropriate amount of water to the base compound in advance. However, in the former method, the effect of improving the reaction rate is not so great, and furthermore, if the amount is reduced too much, it will have a negative effect on the properties after curing.On the other hand, in the method of adding water to the base compound in advance, water and the base compound Due to the inherently poor compatibility with the base compound, water tends to separate from the base compound components during storage, and redispersion when mixing the crosslinking agent is poor, resulting in uneven curing conditions. It was hot. [Object of the Invention] The present invention is intended to solve these problems, and relates to a method for improving the low-temperature curing properties of a sealing material that is crosslinked with an aminoxy group-containing organosilicon compound. [Structure of the Invention] As a result of intensive studies on such a method, the present inventor has found that when mixing the base compound component and the crosslinking agent, water or water and a water-soluble polyhydric alcohol with a molecular weight of 1000 or less or a derivative thereof are combined. It has been discovered that by using a mixture of the above as an additive, the curing properties at low temperatures can be significantly improved without impairing the properties of the sealant, and a uniform curing state can be easily obtained, and the present invention has now been completed. I've reached it. The present invention basically consists of (A) a polydiorganosiloxane whose terminals are blocked with silanol groups and whose viscosity at 25°C is 100 to 200,000 cSt; (B) which has an average number of organoaminoxy groups exceeding two in the molecule. , an aminoxy group-containing organosilicon compound, and (C) an inorganic filler, 100 parts by weight, (D) 5 to 100% by weight of water, and (E) a water-soluble polyhydric alcohol with a molecular weight of 1000 or less or its derivative 95 This is a method for improving the low-temperature curability of a sealant, characterized in that 0.05 to 5 parts by weight of a curing accelerator comprising 0.05 to 0% by weight is added when mixing the sealant composition. The sealant composition (1) to which the present invention is applied basically consists of a polyorganosiloxane as the component (A),
This is a condensation reaction type liquid silicone composition, so-called a deaminoxy type, consisting of an aminoxy group-containing organosilicon compound as component (B) and an inorganic filler as component (C). Component (A), the polyorganosiloxane, is a silanol-terminated polydiorganosiloxane that is normally used in this type of condensed polysiloxane composition that can be cured at room temperature, and in particular provides appropriate extrudability to the composition before curing. In addition, in order to provide the rubber-like elastic body with excellent mechanical properties after curing, the viscosity at 25° C. must be in the range of 100 to 200,000 cSt. If the viscosity is less than 100 cSt, the rubber-like elastic body will not stretch sufficiently after curing.
If it exceeds 200000cSt, a uniform composition cannot be obtained,
Workability also deteriorates. A particularly preferred range is from 500 to 50,000 cSt in terms of harmonizing the properties of the composition before and after curing. Examples of organic groups directly bonded to silicon atoms include alkyl groups such as methyl, ethyl, propyl, butyl, and hexyl; alkenyl groups such as vinyl and allyl; aryl groups such as phenyl; Examples include aralkyl groups such as β-phenylethyl group and β-phenylpropyl group, and monovalent substituted hydrocarbon groups such as 3,3,3-trifluoropropyl group, chloromethyl group, and β-cyanoethyl group. However, due to ease of synthesis, methyl groups, vinyl groups,
or monovalent hydrocarbon radicals such as phenyl radicals are generally preferred. 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, and improves the extrusion workability of the composition before curing and the physical properties of the rubber-like elastic body after curing. 85 of the total organic groups to favor the balance
It is preferable that at least % of the organic groups are methyl groups, and it is more preferable that substantially all the organic groups are methyl groups. However, when the rubber-like elastic body 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 of component (B) constituting the sealant composition is a polydiorganosiloxane [(A)
The polydiorganosiloxane is crosslinked and chain lengthened by performing a dehydroxylamine reaction with the terminal silanol group of the component. It may also be a derivative. For the purpose of obtaining a sealing material with particularly good reactivity, low modulus, and high elongation, a combination of cyclic polysiloxanes having two or three aminoxy groups in one molecule is preferred. 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 pentene 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) ₄ , MeSi (ONEt ₂ ) ₃ , PhSi (ONMe ₂ ) ₃ ,
PhSi( _ONEt2 ) ₃ ,

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

【formula】

【formula】

【formula】

【formula】

【formula】

〔Effect of the invention〕

According to the present invention, even in low-temperature periods such as winter, the sealant can be quickly cured to develop rubber elasticity after being placed, so it can be used to seal joints that are subject to large fluctuations due to diurnal temperature ranges, etc. However, the original performance of the sealant can be demonstrated without constricting or cracking. [Example] The present invention will be explained in more detail with reference to Examples below. In the Examples and Comparative Examples, all parts mean parts by weight, and % means weight %. Example 1 100 parts of silanol-terminated polydimethylsiloxane with a viscosity of 5000 cSt at 25°C was added with an average particle size of 0.2μ.
A base compound was obtained by mixing 50 parts of stearic acid-treated light calcium carbonate in a kneader. For 100 parts of this compound,

[Formula] 94%

A sealant composition was obtained by adding 3.0 parts of a crosslinking agent mixture containing 6% of the formula. To this sealant, a mixture of ethylene glycol, glycerin, ethylene oxide adduct of ethylene glycol, and water shown in Table 1 was added in the amount shown in Table 1, mixed with a spatula, and then sampled.
Got 11-13. A test specimen shown in FIG. 1 was prepared using these samples, and after curing at 10° C. for 4 days, a tensile test was conducted. The results are also shown in Table 1. As a comparative example, Table 1 also shows the results using a sealing material to which these mixtures were not added.

[Table] Example 2 100 parts of silanol-terminated polydimethylsiloxane with a viscosity of 3000 cSt at 25°C was added with an average particle size of 0.6μ.
A base compound was obtained by mixing 65 parts of colloidal calcium carbonate treated with rosin acid using a kneader. For 100 parts of this compound,

[Formula] 95%

A sealing material was obtained by adding 3.0 parts of a crosslinking agent mixture consisting of 5%. A second mixture of ethylene glycol, glycerin, an ethylene oxide adduct of glycerin, and water shown in Table 2 was added to this sealant.
Samples 21 to 23 were obtained by adding the amounts shown in the table and mixing with a spatula. In addition, as comparative examples, samples were prepared in which no curing accelerator was added (sample 31) and samples in which only glycerin was used (sample 32). Regarding these samples, test specimens similar to those in Example 1 were prepared, and after curing at 10° C. for 4 days, a tensile test was conducted. The results are shown in Table 2.

【table】 [Brief explanation of the drawing]

FIG. 1 shows a perspective view of a test specimen used in Examples. The unit in the figure is mm. 1... Sealing material, 2... Adherent (aluminum plate),
3...Foamed polyethylene backup material.

Claims (1)

[Scope of Claims] 1 Basically (A) a polydiorganosiloxane whose ends are blocked with silanol groups and whose viscosity at 25°C is 100 to 200,000 cSt; (B) an organoaminoxy having an average number of more than 2 in the molecule; 100 parts by weight of a sealant composition comprising an aminoxy group-containing organosilicon compound having a group and (C) an inorganic filler, (D) 5 to 100% by weight of water, and (E) a water-soluble polyhydric alcohol with a molecular weight of 1000 or less or A method for improving the low-temperature curability of a sealant, characterized in that 0.05 to 5 parts by weight of a curing accelerator consisting of 95 to 0% by weight of its derivative is added when mixing the sealant composition. 2 Curing accelerator is (D) 10-95% by weight (E) 90-5%
% by weight.