JPH0515748B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to outdoor room temperature curable organopolysiloxane compositions. Specifically, the present invention relates to a dehydroxylamine type outdoor room temperature curable organopolysiloxane composition that does not stain the area around the cured product after curing. Organopolysiloxane compositions that cure at room temperature to form a rubber-like or resin-like state are used as architectural sealants, coating materials, and other materials due to their excellent durability.
It is often used as an adhesive. Among them, dehydroxyamine type room temperature curing organopolysiloxane compositions such as those proposed in Japanese Patent Publication No. 43-24545 and Japanese Patent Application Laid-open No. 52-151349 are used for sealing the joints of buildings and civil engineering structures. However, the problem of causing stains around the cured product has been pointed out mainly by the architectural sealing industry. Therefore, the present inventors conducted intensive studies to develop a dehydroxyamine type room temperature curable organopolysiloxane composition for outdoor use with excellent stain resistance, and as a result, they arrived at the present invention. That is, in the present invention, the terminal silanol group polymerized by the equilibrium polymerization method is
Polystyrene equivalent molecular weight 5000 by gel permeation chromatography using a poor solvent from an organopolysiloxane having at least two molecules in the molecule.
The following organopolysiloxanes are selectively extracted and removed, and the content of organopolysiloxanes with a polystyrene equivalent molecular weight of 5,000 or less as determined by gel permeation chromatography is 3.0% by weight or less, and the viscosity at 25°C is 1,000 to 200,000. Organopolysiloxane that is centistokes and has at least two terminal silanol groups in one molecule
100 parts by weight, (b) filler 5 to 200 parts by weight, and (c) general formula (In the formula, R ¹ , R ² , R ³ are monovalent hydrocarbon groups,
a=2, 3, 4, b=0, 1, 2, a+b=3
~6. ) An organosilicone compound represented by: To explain this, component (a) is the main component of the outdoor room temperature curable organopolysiloxane composition of the present invention, and is crosslinked by component (c) to develop rubber elasticity or rigidity. The reason why the viscosity of component (a) at 25°C is limited to 1,000 to 200,000 centistokes is because if the viscosity is lower than this, the elongation of the cured product will be small and the elastic modulus will be too high, limiting the application. This is because if the viscosity exceeds the viscosity, construction workability will be significantly reduced. Examples of the molecular shape of component (a) include linear, branched, and network. The organic groups bonded to the silicon atom of this organopolysiloxane include alkyl groups such as methyl groups and ethyl groups, alkenyl groups such as vinyl groups, aryl groups such as phenyl groups, 3-chloropropyl groups,
A halogenated alkyl group such as a 3,3,3-trifluoropropyl group is exemplified, and one to three types of these organic groups can be mixed in one molecule. Among these, methyl groups alone or a mixture of methyl groups and other organic groups are common. In component (a), the content of organopolysiloxane with a polystyrene equivalent molecular weight of 5000 or less determined by gel permeation chromatography is 3.0% by weight.
The following description is made in order to achieve the stain prevention property, which is the objective of the present invention. From this viewpoint, the content of organopolysiloxane having a polystyrene equivalent molecular weight of 5000 or less is preferably 2.0% by weight or less. An organopolysiloxane having a terminal silanol group, in particular a diorganopolysiloxane having a silanol group at both ends, which is the main raw material of an outdoor room temperature humidity-curable organopolysiloxane composition, is first produced by a conventionally known method ( Special Public Service 1977-
24545, Japanese Patent Publication No. 46-11272, Japanese Patent Publication No. 49-80200). That is, a cyclic diorganosiloxane oligomer is used as a raw material, polymerized under heating using an alkali catalyst, then water is added and further heated, and after reaching an equilibrium state, the catalyst is removed or deactivated, and then a low boiling point cyclic diorganosiloxane oligomer is polymerized. By removing the siloxane oligomer by distillation under reduced pressure, or by polymerizing under heating using an acid catalyst using a mixture of a cyclic diorganosiloxane oligomer and a diorganosiloxane oligomer having silanol groups at both ends or a small amount of water as a raw material, After reaching an equilibrium state, the catalyst is removed or deactivated, and the cyclic diorganosiloxane oligomer having a low boiling point is further removed by distillation under reduced pressure, thereby obtaining a diorganosiloxane oligomer having silanol groups at both ends. From organopolysiloxanes having terminal silanol groups, organopolysiloxanes with a polystyrene equivalent molecular weight of 5000 or less are removed by gel permeation chromatography to determine their content.
To reduce the molecular weight to 3.0% by weight or less, perform severe vacuum distillation or use a poor solvent such as ethanol, methanol, acetone, etc. In other words, reduce the polystyrene equivalent molecular weight by gel permeation chromatography.
When a solvent that does not substantially dissolve organopolysiloxanes larger than 5,000 but dissolves organopolysiloxanes whose molecular weight is smaller than 5,000 is added and left to stand after sufficient stirring, it will separate into two layers, so remove the poor solvent layer. However, this can be achieved by repeating the operation of adding a poor solvent to this again, stirring thoroughly, and then allowing it to stand to remove the poor solvent layer. The content of organopolysiloxane having a polystyrene equivalent molecular weight of 5000 or less by gel permeation chromatography (hereinafter referred to as "GPC") is measured by the following method. That is, the molecular weight distribution obtained by GPC is divided into a low molecular weight region and a high molecular weight region at a count number corresponding to a molecular weight of 5000, and the component ratio is calculated based on the area ratio of each. Here, the molecular weight is calculated from a calibration curve obtained by plotting the molecular weight and count number from GPC charts of polystyrene of several standard molecular weights. Component (b) used in the present invention has the effect of imparting viscosity to the composition of the present invention and improving mechanical properties after curing. These can be roughly divided into reinforcing fillers and extender fillers. Examples of reinforcing fillers include fumed silica, surface-hydrophobized fumed silica, carbon black, ultrafine calcium carbonate, and fumed titanium oxide, and examples of extender fillers include diatomaceous earth, fine quartz powder, and heavy Examples include calcium carbonate, glass fiber fine powder, carbon fiber fine powder, titanium dioxide, and iron oxide. (b) If the amount of component added is too small, the viscosity of the composition of the present invention will be too low and it will be difficult to work with. Conversely, if the amount added is too large, the viscosity of the composition of the present invention will increase significantly.
Since workability becomes worse, the amount added should be less than that of component (a).
The amount is 5 to 200 parts by weight per 100 parts by weight. In general, reinforcing fillers need to be added in smaller amounts than extender fillers, preferably 10 to 60 parts by weight. Extending filler is preferably 40 to 150 parts by weight. A reinforcing filler and an extender filler may be used in combination. Component (c) used in the present invention is a crosslinking agent and chain extender of component (a). (a) Terminal silanol group of component
It is cured by a condensation reaction with the N,N-diorganoaminoxy group of component (iii) while eliminating N,N-diorganohydroxylamine. Those with two N,N-diorganoaminoxy groups in one molecule act as chain extenders, and those with three or more N,N-diorganoaminoxy groups in one molecule function as crosslinking agents. do. In the general formula, R ¹ is a monovalent hydrocarbon group, which includes alkyl groups such as methyl, propyl, and hexyl; phenyl; and haloalkyl groups such as 3,3,3-trifluoropropyl. For example, a methyl group is preferred. R ² is also a monovalent hydrocarbon group, and examples thereof include those similar to R ¹ and aralkyl groups such as 2-phenylethyl group and 1-phenylethyl group. R ³ is also a monovalent hydrocarbon group, and the same ones as R ² are exemplified, but from the viewpoint of the curability of the composition of the present invention, it is preferably an alkyl group having 6 or less carbon atoms, and most preferably an ethyl group. . Examples of component (iii) include those represented by the following structural formula. In addition to these, organosilicone compounds having two or more aminoxy groups in one molecule are known, but acyclic aminoxy group-containing organosilicone compounds cannot be used in the composition of the present invention. This is because the reactivity of the acyclic aminoxy group-containing organosilicone compound is low, so the reaction with component (A) cannot be completed, and a large amount of component (A) remains which is not incorporated into the crosslinked structure. This is because it causes stains around the cured product of the organopolysiloxane composition. If the amount of component (c) added is too small, a sufficient curing reaction will not occur, and a large amount of unreacted component (a) will remain, causing stains, and if it is too large, the characteristics of this type of crosslinking agent However, surface hardening takes priority, water vapor dispersion is suppressed, deep hardening properties are reduced, and curing reaction by-products cause cleavage of siloxane bonds, resulting in lower modulus. The amount is 1.5 to 20 parts by weight per 100 parts by weight of component (a). The composition of the present invention can be produced by mixing components (a), (b), and (c) until uniform. Generally, it is used as a two-component curable composition in which a mixture of components (a) and (b) and component (c) are mixed immediately before use. The thus obtained outdoor room temperature curable organopolysiloxane composition of the present invention is characterized in that it cures at room temperature to become rubber-like or resin-like, and does not contaminate the various substrates to which the cured product is adhered. It is extremely useful as a building sealant, various coating materials, adhesives, etc. used outdoors. The present invention will be explained below with reference to examples.
In the examples, all "parts" mean "parts by weight," viscosity is a value measured at 25°C, and molecular weight is a polystyrene equivalent molecular weight. Example 1 Polymerized by equilibrium polymerization method, cyclic dimethylsiloxane oligomer was removed by vacuum distillation, molecular weight 5000
The following α,ω-dihydroxydimethylpolysiloxane containing 6.8% by weight of low molecular weight dimethylpolysiloxane and having an average viscosity of 5000 centistokes was extracted 2 to 12 times with approximately the same amount of acetone or ethanol. A raw material α,ω-dihydroxydimethylpolysiloxane was prepared by removing as much of the low molecular weight dimethylpolysiloxane with a molecular weight of 5000 or less as possible. The contents are shown in Table 1. 100 parts of these raw materials α,ω-dihydroxydimethylpolysiloxane are mixed with 60 parts of calcium carbonate having an average particle size of 0.5μ to form a base ingredient, and the following three hardening agents F to H are added to the base ingredient as shown in Table 2. Room temperature curable organopolysiloxane composition No.
1 to No. 7 were prepared. These room-temperature-curable organopolysiloxane compositions were filled into a 20 mm wide and 10 mm deep joint between two white ceramic boards and cured at room temperature for one week to prepare test panels. This test panel was left outdoors at an angle of 75 degrees with the joints facing up, and the occurrence of stains was examined over a period of two months. In addition, sheets with a thickness of 1 mm were prepared using room-temperature-curable organopolysiloxane compositions No. 1 to No. 7, and after curing at room temperature for two weeks or more,
~2 mm was chopped into cubic dimensions. Approximately 10 g of the shredded cured material was mixed with chloroform.
After soaking in 100 to 150 g for one week, the amount of extraction was determined. Table 3 shows the occurrence of stains and the measurement results of the amount extracted. In addition, the molecular weight distribution of organopolysiloxane extracted from the cured products No. 1 and No. 5 was measured. From these results, we found the following. 1 The content of low molecular weight dimethylpolysiloxane in the raw material α,ω-dihydroxydimethylpolysiloxane is 3.0% by weight or less, and
When a cyclic aminoxy group-containing organosilicone compound is used as a curing agent, almost no staining is observed on the ceramic board. The amount of chloroform extracted from the cured products is 3.5% by weight or less. 2. If the content of low molecular weight dimethylpolysiloxane in the raw material α,ω-dihydroxydimethylpolysiloxane is more than 3.0% by weight, or if an acyclic aminoxy group-containing organopolysiloxane is used as a curing agent, the hardening agent Staining occurs and the amount of chloroform extracted from the cured product exceeds 3.5% by weight. 3 In the molecular weight distribution of organopolysiloxane extracted from the cured product of No. 5, almost no peak of low molecular weight dimethylpolysiloxane was observed, and a peak was observed at almost the same position as the raw material α,ω-dihydroxydimethylpolysiloxane. Considering that stains were generated around the joint No. 5 in a short period of time, the unreacted raw material α,ω-dihydroxydimethylpolysiloxane was also the cause of the stains.

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[Table] Example 2 40 x 40 x 5 cm mikage stone, intersecting in the center
A cross-shaped joint of 1 cm deep and 2 cm wide was cut in a 40 cm x 40 cm cross shape, filled with No. 7 composition from Example 1, and after curing at room temperature for one week, it was placed on the roof of an 8-story building in Tokyo at 75 degrees Celsius. It was left for 6 months with a slope of . Incidentally, Primer B manufactured by Torre Silicone Co., Ltd. was applied to the mikageite in advance. Even after 6 months, there is no staining around the joints.
Almost no stains were observed, indicating excellent stain prevention properties. Example 3 A polysiloxane with a molecular weight of 5000 or less obtained by polymerizing octamethylsilolotetrasiloxane and tetramethyltetraphenylcyclotetrasiloxane at a molar ratio of 9:1 by an equilibrium polymerization method, and removing the cyclic diorganosiloxane oligomer by distillation under reduced pressure. An α,ω-dihydroxydimethylsiloxane/methylphenylsiloxane copolymer with a content of 5.7% by weight and an average viscosity of 3840 centistokes was extracted five times with approximately twice the amount of acetone. A raw material α,ω-dihydroxydimethylsiloxane/phenylsiloxane copolymer (molar ratio of both siloxane units: 9:1) was prepared. This siloxane copolymer had an average viscosity of 4130 centistokes and a polysiloxane content of 0.7% by weight having a molecular weight of 5000 or less. This raw material α,ω-dihydroxydimethylsiloxane/methylphenylsiloxane copolymer 100
40 parts by weight of fumed silica with a specific surface area of 200 m ² /g treated with surface hydrophobization with hexamethyldisilazane, formula Room temperature curable organopolysiloxane composition No. 7 was prepared by mixing 7.2 parts of a curing agent represented by the formula until homogeneous.
8 was prepared. Regarding this room-temperature curable organopolysiloxane composition No. 8, the stain generation status and chloroform extraction amount were investigated in the same manner as in Example 1, and no stains were generated even after 2 months, and the chloroform extraction amount was 1.8% by weight. It was hot. Comparative Example 6 and Comparative Example 7 The α,ω-dihydroxydimethylpolysiloxane used in Example 1, that is, contains 6.8% by weight of low molecular weight dimethylpolysiloxane with a molecular weight of 5000 or less, polymerized by equilibrium polymerization method, and has an average viscosity of α,ω-dihydroxydimethylpolysiloxane with a temperature of 5000 centistokes was placed in a glass thin-film distillation apparatus [2-03 thin-film distillation apparatus manufactured by Shinko Faudler Co., Ltd.] and heated to 150℃/10 ^-3 mmHg and
As much as possible of the low molecular weight dimethylpolysiloxane with a molecular weight of 5000 or less contained in the α,ω-dihydroxydimethylpolysiloxane was distilled off under reduced pressure conditions of 200°C/10 ^-3 mmHg. The content of the obtained α,ω-dihydroxydimethylpolysiloxane was measured in the same manner as in Example 1. These results are shown in Table 4. 100 parts of these raw materials α,ω-dihydroxydimethylpolysiloxane are mixed with 60 parts of calcium carbonate with an average particle size of 0.5μ to form a base ingredient, and 4.8 parts of curing agent G is mixed with these base ingredients to form a room temperature curable resin. Organopolysiloxane compositions No. 8 and No. 9 were prepared. Test panels were prepared in the same manner as in Example 1 using these room temperature curable organopoisiloxanes. Regarding this test panel, the occurrence of stains was examined in the same manner as in Example 1. These results are shown in Table 5 as Comparative Example 6 and Comparative Example 7. From these results, α, ω polymerized by equilibrium polymerization
It has been found that a dehydroxyamine-type organopolysiloxane composition containing α,ω-dihydroxydimethylpolysiloxane as a main ingredient obtained by distilling -dihydroxydimethylpolysiloxane under reduced pressure causes staining after curing.

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Claims (1)

[Scope of Claims] 1 (a) An organopolysiloxane having at least two terminal silanol groups in one molecule polymerized by an equilibrium polymerization method and having a polystyrene equivalent molecular weight of 5000 or less by gel permeation chromatography using a poor solvent. The content of organopolysiloxane, which is obtained by selective extraction and removal of polysiloxane and has a polystyrene equivalent molecular weight of 5000 or less as determined by gel permeation chromatography, is 3.0% by weight or less, and the viscosity at 25°C is 1000 to 200000 centistokes. 100 parts by weight of an organopolysiloxane having at least two terminal silanol groups per molecule, (b) 5 to 200 parts by weight of a filler, and (c) General formula (In the formula, R ¹ , R ² , R ³ are monovalent hydrocarbon groups,
a=2, 3, 4, b=0, 1, 2, a+b=3
~6. ) A room temperature-curable organopolysiloxane composition for outdoor use, comprising 1.5 to 20 parts by weight of an organosilicone compound represented by: 2. The outdoor room temperature curable organopolysiloxane composition according to claim 1, wherein the poor solvent is ethanol or acetone.