JPH0341110B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention provides a curable composition, particularly for protecting the surfaces of various objects such as metals, plastics, ceramics, glass, and wood, providing stain resistance, electrical insulation properties, and powder flowability. The present invention relates to a room-temperature curable composition comprising, as a main ingredient, an alkenoxy group-containing organopolysiloxane which is used for imparting properties. (Conventional technology) Metals, plastics, ceramics, glass,
It is already widely used to coat the surfaces of various objects such as wood with silicone resin compositions for the purpose of imparting impact resistance, solvent resistance, mold releasability, water repellency, weather resistance, heat resistance, electrical insulation properties, etc. Organopolysiloxane resins having hydroxyl groups bonded to silicon atoms are widely used as silicone resin compositions. Conventionally, curing of this type of organopolysiloxane resin has been carried out by heating the coating film to a high temperature of 150°C or higher, but room-temperature-curable silicone resin compositions containing alkyl acetoxysilane have been used. (See US Pat. No. 2,615,861), and room temperature curable silicone resin compositions containing aminoalkylalkoxysilane (see US Pat. No. 3,350,349). However, these resin compositions have very poor storage stability and must be mixed immediately before use, and the cured film has the disadvantages of poor solvent resistance and poor adhesion. Therefore, in order to improve the storage stability of this type of composition, a composition comprising a ketoxime group-containing organopolysiloxane and an aminoalkylalkoxysilane has been proposed (Japanese Patent Publication No. 47
However, this method has the disadvantage that the ketoxime generated during curing is toxic and corrosive, so it cannot be used for copper coating. Room-temperature curable compositions containing organopolysiloxane and aminoalkylalkoxysilane added (see Japanese Patent Publication No. 15827/1982) have good storage stability and are not corrosive, but require a long time for internal curing of the film. However, this cured film has a disadvantage of being inferior in strength. In addition, this composition uses a diorganopolysiloxane whose molecular chain ends are blocked with hydroxyl groups.

It is also known that cross-linking is carried out with an organosilane represented by the formula (Tokuko Sho
No. 51-39274, Special Publication No. 51-39673, Special Publication No. 54-
However, these compositions are soft and difficult to form into thin films, and have the disadvantage that they cannot provide impact resistance, solvent resistance, etc. as protective coatings for various substrates. (Structure of the Invention) The present invention relates to a room-temperature curable coating agent composition that solves the above-mentioned disadvantages.

[Formula] (where R ¹ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, R ² and R ³ are each a hydrogen atom or a carbon number 1
~8 unsubstituted or substituted monovalent hydrocarbon groups, n, m
are alkenoxy group-containing organopolysiloxanes represented by 0.8≦n≦1.8 and 0<m<2), respectively.
100 parts by weight, 2) General formula

[expression] or

[Formula] (where R ⁴ and R ⁵ are hydrogen atoms, alkyl groups, aryl groups, aminoalkyl groups, N-alkylaminoalkyl groups,
An atom or group selected from N,N-dialkylaminoalkyl group, alkylene group, and oxyalkylene group, R ⁶ is an unsubstituted or substituted divalent hydrocarbon group having 1 to 6 carbon atoms, R ⁷ and R ⁸ are each carbon Number 1~
8 unsubstituted or substituted monovalent hydrocarbon group, q is 0 or 1) 0.01 to 20 parts by weight of an alkoxysilane or a partial hydrolyzate thereof, and 3) 0 to 10 parts by weight of an organotin compound. This is a characteristic feature. That is, the present inventors have the above-mentioned disadvantages,
As a result of various studies on room-temperature curable compositions without any drawbacks, we found that the main ingredient is an alkenoxy group-containing organopolysiloxane represented by the above general formula, and an alkoxysilane represented by the above general formula or a partially hydrolyzed product thereof. The hydroxyl groups involved in cross-linking are all blocked by alkenoxysilyl groups, so they do not condense in the absence of moisture and can be stored stably for at least 6 months. During curing, the active silanol groups instantly condense and crosslink as ketones are released, resulting in a film that has high adhesion, as well as impact resistance, bending resistance, and solvent resistance. In addition to discovering that this product has excellent properties, this product does not release amines, which have been a problem in the past due to the release of harmless ketones during curing.
The present invention was completed after confirming that no toxic or corrosive gases such as acetic acid or ketoxime are emitted. The alkenoxy group-containing organopolysiloxane as the first component constituting the curable composition of the present invention has the general formula ^R1 is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, a dodecyl group, an octadecyl group, a cycloalkyl group such as a cyclohexyl group, an alkenyl group such as a vinyl group or an allyl group, Selected from aryl groups such as phenyl group and tolyl group, or chloromethyl group, trifluoropropyl group, cyanoethyl group, etc. in which part or all of the hydrogen atoms bonded to the carbon atoms of these groups are substituted with halogen atoms, cyano groups, etc. unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, R ² and R ³ are hydrogen atoms or unsubstituted or substituted monovalent hydrocarbon groups having 1 to 8 carbon atoms similar to R ¹ , n, m
are 0.8≦n≦1.8 and 0<m<2, respectively, but from the viewpoint of the strength of the film obtained from this composition, the m value is preferably set in the range of 0.01<m<0.5. , Examples of this include the following: (p ₁ to _{p 6} are positive numbers of 3 or more) In addition, this alkenoxy group-containing organosiloxane is a silanol group-containing organopolysiloxane whose hydroxyl group is expressed by the general formula

[Formula] (where R ¹ , R ² and R ³ are the same as above, r is 0 or 1) or by silylation with an alkenoxysilane compound or a partial hydrolyzate thereof Can be done. Therefore, in this production, one or a mixture of two or more chlorosilanes having 0.8 to 1.8 monovalent hydrocarbons per silicon atom is hydrolyzed in the presence of an organic solvent to form silanol groups. If an alkenoxysilane or a partial hydrolyzate thereof is reacted with an organosiloxane containing an organosiloxane prepared by polymerizing it as necessary to condense a part of the silanol groups, the hydroxyl group becomes silylated at room temperature. An alkenoxy group-containing organopolysiloxane represented by the above formula (1) can be obtained. However, in this organosiloxane, the alkenoxy group bonded to the silicon atom is 0.01
If it is less than 40% by weight, crosslinking will not proceed effectively even in the presence of the aminoalkylalkoxysilane described later and a cured film will not be formed, and if it exceeds 40% by weight, there will be too many functional groups and the film will become brittle. m so that it is in the range of 0.01 to 40% by weight
It is necessary to set the value of . In order to do this, the degree of polymerization must be adjusted so that the content of hydroxyl groups bonded to silicon atoms in the raw material resin falls within this range, but the alkenoxysilane compound that can be silylated is methyltritrisilane. (isopropenyloxy)silane, vinyltri(isopropenyloxy)silane, phenyltri(isopropenyloxy)silane, propyltri(isopropenyloxy)silane, tetra(isopropenyloxy)silane, methyltri(1-phenylethenyloxy) Silane, methyltri(1-isobutenyloxy)silane, methyltri(1-methyl-1-
Examples include propenyloxy)silane and partially hydrolyzed products thereof. Next, the aminoalkylalkoxysilane as the second component constituting this curable composition has the general formula

[Formula] or and R ⁴ and R ⁵ are selected from a hydrogen atom, an alkyl group, an aryl group, an aminoalkyl group, an N-alkylaminoalkyl group, an N,N'-dialkylaminoalkyl group, an alkylene group, and an oxyalkylene group. Atom or group, R ⁶ is an unsubstituted divalent hydrocarbon group having 1 to 6 carbon atoms such as methylene group, ethylene group, propylene group, phenylene group, R ⁷ and R ⁸ are
R ¹ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and q is 0 or 1. It acts as an accelerator, improves the adhesion of the cured film obtained from the composition of the present invention to the substrate, and can also control the amount of charge on the object coated with this composition. These compounds include 3-aminopropyltriethoxysilane, 3-
(N,N'-dimethylamino)propyltriethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3-morpholinopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(2- aminoethylamino)propylmethyldimethoxysilane, 3-
(N-methylamino)propyltriethoxysilane, 3-piperidinopropyltriethoxysilane, 3-(N,N,N',N'-tetramethylguanidinopropyl)trimethoxysilane, 3-(N,
N,N',N'-tetramethylguanidinopropyl)
Methyldimethoxysilane, 3-(N,N-ethylmethyl-N',N'-ethylmethylguanidinopropyl)trimethoxysilane, 3-(N,N-methylphenyl-N',N'-methylphenylguanidinopropyl) trimethoxysilane, 3-(N,N,
Examples include N',N'-tetramethylguanidinopropyl)tri(isopropenyloxy)silane and partial hydrolysates thereof. If the amount of the second component added is less than 0.01 part by weight based on 100 parts by weight of the alkenoxy group-containing organopolysiloxane as the first component, the curability of this composition will be poor, and the resulting cured film will not have a good curability. The adhesion will be poor, and if it exceeds 20 parts by weight, the resulting cured film will discolor at high temperatures.
A range of 0.01 to 20 parts by weight is required. Further, in order to accelerate the reaction of the composition of the present invention, an organic tin compound is added as a third component as necessary, but this includes dibutyltin diacetate, which is usually used for dehydration condensation of silanol, Examples include dibutyltin dioctate, dibutyltin dilaurate, stannous octylate, and stannous naphthenate, which may be added in an amount of 0 to 10 parts by weight. The curable composition of the present invention can be obtained by uniformly mixing predetermined amounts of the first to third components described above, and may be applied as is to the object to be treated. If the viscosity is relatively high, it is often diluted with an organic solvent for coating purposes. Examples of such organic solvents include toluene, xylene, ethylbenzene, hexane,
Examples include octane, industrial gasoline, cyclohexane, trichloroethylene, 1,1,1-trichloroethane, chloroform, and carbon tetrachloride, but toluene and xylene are preferable because they have high solubility in organopolysiloxane. As mentioned above, the coating agent composition of the present invention obtained as described above can be stored stably for at least 6 months, and upon curing, it releases ketones and hardens rapidly, and the resulting cured film is Because it adheres well to objects, silicone films with excellent physical properties can be formed on the surfaces of metals, plastics, ceramics, glass, wood, etc. The cured films obtained in this way are hard, have good bending resistance, Impact resistance, solvent resistance, mold releasability, water repellency,
Because of its excellent weather resistance, heat resistance, and electrical insulation properties, it is used as a coating agent to protect the workpiece from the effects of light, air, water, corrosive gases, solvents, etc., as well as oil, mud, dirt, and water scale. It is said to be useful as a coating agent to prevent the adhesion of substances such as, a coating agent to make the surfaces of various objects electrically insulating, and a coating agent to reduce resistance during the flow of various powders. This coating agent composition can be applied to various base materials such as those mentioned above, so specifically, it can be applied to transportation equipment such as automobiles and various vehicles, electrical equipment such as relays, terminals, printed circuit boards, electrical contacts, etc. It is said to be useful for construction purposes such as electronic equipment, pipes, bridges, buildings, tiles, and window glass, and for processing various molds, utility poles, cooking utensils, ferrite powder, iron powder, etc. Next, examples of the present invention will be given, in which parts in the examples indicate parts by weight, and various test results in the examples are those obtained by the following methods. (Pencil hardness)...According to JIS K5400, Section 6-14. (Adhesion)…Cut the grooves according to JIS K5400, Section 6-15, and
The number remaining after 100 pieces were crimped with cellophane tape and then peeled off is shown. (Bending resistance)...According to JIS K5400, Section 6-16 (mandrel test 2mmφ). [〇...Pass, ×...Fail] (Impact resistance)...According to JIS K5400, Section 6-13 (dupont type 1/2 inch x 500g x 50
cm). [〇…Pass, ×…Fail] (Solvent resistance)…100g of gauze soaked in xylene
It is expressed as the number of reciprocations until the film peels off when the film is reciprocated under a load of . (Heat resistance): Changes in the appearance of the film after heating at 250°C for 24 hours were observed with the naked eye. 〇…
No abnormality, ×... Abnormality] (Accelerated weather resistance): The appearance of the film was observed with the naked eye after 500 hours using Atlas Cobucon (a cycle of ultraviolet irradiation at 70°C for 8 hours and humidity at 50°C for 4 hours). 〇…
No abnormality, ×... Abnormality] (Storage stability) The resin composition was left in a closed container at room temperature and the state of viscosity change or gelation was examined. (Corrosive)... Coating agent 50 x 150 x 0.3 mm
The surface condition was observed with the naked eye after it was applied to a copper plate and left at room temperature for one month. Examples 1 to 5, Comparative Examples 1 to 2 Methyltrichlorosilane (CH ₃ SiCl ₃ ) 80 mol% and dimethyldichlorosilane [(CH ₃ ) ₂ SiCl ₂ ] 20
mol% and co-hydrolyzed in the presence of toluene to obtain silicon-bonded hydroxyl groups of 0.8% by weight, 1.2% by weight, and 1.5% by weight.
of the three organopolysiloxanes containing % by weight.
After preparing 50% toluene solutions A, B, and C, the following alkenoxysilanes a and b were added in the amounts shown in Table 1 to 100 parts of this organopolysiloxane, and the mixture was heated at room temperature under a nitrogen gas atmosphere. The reaction was carried out for 2 hours to produce the alkenoxy group-containing organopolysiloxanes shown in Table 1. (alkenoxysilane)

[Table] Next, to 100 parts of this alkenoxy group-containing organopolysiloxane, aminoalkylalkoxysilanes c, d, e, f and an organotin compound in the amounts shown in Table 2 were added to form coating compositions 1 to 1.
No. 5 was prepared, and this was poured onto a 50 x 150 x 0.3 mm polished mild steel plate to a thickness of 20 μm, left to harden at room temperature for 48 hours, and the physical properties of the resulting cured film were investigated. The results shown in the table were obtained. ( _{Aminoalkylalkoxysilane} ) c...( _CH3 ) _2N ( _{CH2 ) 3Si} ( _OC2H5 ), d...( _CH3O ) _{3Si ( CH2 ) 3NHCH2CH2NH2} , e... _H2N ( _CH2 ) _3Si ( _OC2H5 ) ₃ , f...[( _CH3 ) _2N ] _{2C =} N( _CH2 ) _3Si ( _OCH3 ) ₃ . For comparison, 50% of the hydroxyl group-containing organopolysiloxane obtained above was used instead of the alkenoxy group-containing organosiloxane above.
To 100 parts of toluene solution B, add 15 parts of methyltrimethoxysilane [CH ₃ Si (OCH ₃ ) ₃ ] or methyl tris (ethyl methyl ketoxime) silane.

[Formula] Add 30 parts to make organopolysiloxane, and then add 5 parts of the above aminoalkylalkoxysilane d and 1 part of dibutyltin diacetate to 100 parts of this organopolysiloxane to make coating agents 6 and 7. , after examining these physical properties, we found that
This showed the results as shown in Table 3.

【table】

【table】

【table】

[Claims]

1 A) General formula

[Formula] (where R ¹ and R ² are the same or different unsubstituted or substituted monovalent hydrocarbon groups, and m is an integer of 5 or more) A diorganopolymer whose molecular chain ends are blocked with hydroxyl groups. Siloxane 100 parts by weight, B) General formula R ³ _4-a SiX _a (where R ³ is an unsubstituted or substituted monovalent hydrocarbon group, x is a hydrolyzable group,
organosilane (a is a positive number of 2<a<4) or its partial hydrolyzate
0.5 to 30 parts by weight, C) Humid silica 3 to 100 parts by weight,

Claims (1)

0.01 to ^{20 parts} by weight of an alkoxysilane or a partial hydrolyzate thereof, 3 ) A curable composition comprising 0 to 10 parts by weight of an organic tin compound.