JPS6360071B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a curable composition, particularly a silicone composition that exhibits rapid curing at room temperature even in the absence of a catalyst and provides a cured film with excellent adhesion to a substrate. Room-temperature curable silicone compositions are made by combining a hydroxy-terminated polysiloxane that cures with moisture in the air, an organosilicon compound such as acyloxysilane, alkoxysilane, acyloxysilane, or aminosilane, and a curing catalyst. Room-temperature-curable silicone rubber compositions are well known, and silicone resin-based compositions that cure to form a hard film also contain silanol groups (≡
It is known to condense a silanol group (SiOH) or a silanol group and an alkoxy group (≡SiOR) in the presence of a metal fatty acid salt or an amine catalyst. However, since the storage stability of products to which this catalyst is added deteriorates, it is necessary to add this catalyst immediately before use.Therefore, it is necessary to use a two-component system, resulting in poor workability and Even when used, drawing hardening takes a long time, and heating is required to harden in a short time, which is a disadvantage. Regarding the curing reaction of silicone compositions, there are methods in which silicon-bonded olefin groups are polymerized together in the presence of a peroxide-based curing catalyst, and silicon-bonded olefin groups and silicon-bonded hydrogen atoms are polymerized. It is known that an addition reaction is carried out in the presence of a platinum-based catalyst, but in the former case heating is required, and in the latter case, in order to make it curable at room temperature, these two-component systems must be reacted immediately before use. In addition, the cured product of each type has poor adhesion to the base material, and the faster the curing, the worse the adhesion becomes. There is a disadvantage that, as a countermeasure to this problem, it is necessary to apply a primer to the base material surface in advance. The present invention relates to a silicone-based curing composition that overcomes these disadvantages, and is comprised of A)
in the molecule

[Formula] unit and R ² Si (NR ³ ) _3/2 unit (where R ¹ , R ² , R ³ are hydrogen atoms or groups selected from the same or different unsubstituted or substituted monovalent hydrocarbon groups, (a) is a number selected from 1, 2, and 3); and (B) an organic solvent. That is, the present inventors showed rapid hardening at room temperature,
As a result of various studies on curable silicone compositions that give cured products with excellent adhesion to substrates, we found that organosilazane siloxane polymers such as those described above can be easily cured at room temperature even in the absence of a catalyst, and that the cured products can be cured easily. It was discovered that this organosilazane siloxane polymer adheres well to the substrate without applying a primer, etc., and if the organopolysiloxane structure contained in this organosilazane siloxane polymer is appropriately selected, it can be used to form rubber-like to hard resin-like materials. The present invention was completed by confirming that a cured product with a wide range of properties could be obtained. The organosilazane siloxane polymer as the main component constituting the curable silicone composition of the present invention has the general formula

[Formula], R ¹ is a hydrogen atom, a methyl group, an ethyl group,
Alkyl groups such as propyl and butyl groups, aryl groups such as phenyl and tolyl groups, alkenyl groups such as vinyl and allyl groups, cycloalkyl groups such as cyclohexyl, and hydrogen bonded to carbon atoms of these groups. Same or different unsubstituted or substituted monovalent hydrocarbon groups selected from groups in which part or all of the atoms are substituted with halogen atoms such as chlorine atoms, cyano groups, etc., where a is an integer of 1 to 3. siloxane units with the general formula R ² Si(NR ³ ) _3/
2 ^, in which R ² and R ³ contain at least one silazane unit selected from a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group of the same type or different type as R 1 described above. shall be included.
This type of organosilazane siloxane polymer has the following general formula:

[Formula] (Here, R ¹ is the same as above, 0<c<4, 0<
d<4, 0<c+d<4). At least one silicon-halogen bond (≡
2) an organopolysiloxane having SiX);
It can be easily obtained by reacting an organosilicon compound having at least one silicon-halogen bond in the molecule with ammonia or a primary amine in the presence of an organic solvent. The organopolysiloxane of 1) used as the starting material in the above reaction has the following formula C1 _3-a R ¹ _a SiO (R ¹ ₂ SiO) _n SiR ¹ _a C1 _3-a , C1 _3-a R ¹ _a SiO
(R ¹ ₂ SiO) _n (C1R ¹ SiO) _o −SiR ¹ _a C1 _3-a , C1 _4-ac R ¹ _a
Si−{O(R ¹ ₂ SiO) _n (C1R ¹ SiO) _o SiR _a C1 _3-a } _c , C1 _3-a R ¹ _a SiR ⁴ (R ¹ ₂ SiO) _n −R ¹ SiR ⁴ SiR ¹ _a C1 _3-a , C1 _3-a R ¹ _a SiO (R ¹ ₂ SiO) _n (R ¹ ₂ SiR ⁴ ) _o −SiR ¹ _b C1 _3-b , (In the formula, R ¹ and a are the same as above, and R ⁴ is a non-selective group of the same or different type selected from alkylene groups such as ethylene, propylene and butylene groups, and arylene groups such as phenylene and methylphenylene groups. Substituted or substituted divalent hydrocarbon groups, b = integer of 1 to 3, C = integer of 1 to 4, m, n, p are arbitrary positive numbers) are exemplified; It may be a mixture. This organopolysiloxane has an equilibrium polymerization of organocyclic siloxane and organochlorosilane such as dichlorodimethylsilane, trichloromethylsilane, tetrachlorosilane, etc., partial hydrolysis of organohalosilane, silicon hydrogen bond (≡SiH) It can be produced by chlorination of organohydrodiene polysiloxane or addition reaction of this with a chlorine-containing alkenylsilane, or addition reaction of a chlorine-containing hydrosilane to an alkenyl group-containing polysiloxane. In addition, the organosilicon compounds of 2) above used in this reaction have the following general formulas R ² _b SiX _4-b (X is a halogen atom), C1 _3-b R ² _b Si (R ² ₂ Si)
_n (C1R ² Si) _o − (C1 ₂ Si) _p SiR ² _b C1 _3-b , C1 _3-b R ² _b SiR ⁴
(R ² ₂ SiR ⁴ ) _n (C1RSiR ⁴ ) _o − (C1 ₂ SiR ⁴ ) _p SiR ² _b C1 _3-b ,
R ² _b Si (OR ² ) _d X _4-bd (R ² , R ⁴ , b, m, n, p are the same as above, d
=1-3, b+b=1-2), and may be a mixture of the various silanes mentioned above. These organosilicon compounds can be used, for example, in chlorination of organopolysilanes having silicon hydrogen bonds (≡SiH), addition reactions between chlorine-containing alkenylsilanes and chlorine-containing silanes having ≡SiH bonds, or as parts of chlorine-containing silicon compounds. It can be produced by alkoxylation. The organosilazane siloxane polymer mentioned above is the organopolysiloxane mentioned above in 1) and 2).
It is obtained by reacting an organosilicon compound with ammonia or a primary amine such as methylamine, ethylamine, butylamine in an organic solvent, but ammonia and ammonia are usually used as the reaction agent for ease of synthesis. It is good to do. Also,
There are no particular restrictions on the organic solvent used here, as long as it is inert to ammonia gas and primary amines and can dissolve the organosilazane siloxane polymer produced in this reaction. Examples include dichloromethane, trichloroethane, methylene chloride, diethyl ether, tetrahydrofuran, benzene, toluene, xylene, etc., but this amount is determined based on the amount of ammonium chloride produced as a by-product in this reaction and the amount that gelation does not occur during the reaction. It may be selected appropriately from the range. Incidentally, since this reaction is an exothermic reaction, there is no particular need for heating, and it is preferable to carry out the reaction at a temperature in the range of 0 to 50°C. Furthermore, the mixing ratio of organopolysiloxane and organosilicon compound when carrying out this reaction is not particularly limited, and may be varied within a wide range depending on the type and properties of the organosilazane siloxane polymer to be used. can be done, but
When this organosilicon compound has a relatively high chlorine content, the resulting organosilazane siloxane polymer has a high content of highly hydrolyzable silazane bonds, resulting in a fast curing speed. Furthermore, when the organopolysiloxane has a high chlorine content, the resulting organosilazane polymer has a fast curing speed. Note that by appropriately selecting the above-mentioned chlorine-containing organopolysiloxane and organosilicon compound used in this reaction, the structure of the resulting organosilazine silokine polymer can be made arbitrary, for example, If a linear polysiloxane containing chlorine at the terminal is used as the organopolysiloxane, an organosilazane siloxane polymer having a linear polysiloxane structure as the main skeleton can be obtained. The curable silicone composition of the present invention is composed of the organosilazane siloxane polymer obtained as described above and an organic solvent, but the organic solvent is not particularly limited as long as it dissolves the organosilazane siloxane polymer as the main component. This includes hydrocarbon compounds such as benzene, toluene, xylene, dichloromethane, trichloroethane,
Examples include chlorinated hydrocarbons such as methylene chloride, ether compounds such as diethyl ether and tetrahydrofuran, ketone compounds such as acetone, methyl ethyl ketone, methyl isopropyl ketone, and methyl isobutyl ketone, and mixtures thereof. There is no particular limit to the content of this organic solvent in the curable composition, but it depends on the required viscosity and formation method depending on the structure and use of the organosilazane siloxane polymer as the main component, and the coating film formation method. It may be adjusted based on the film thickness, etc.
Further, this organic solvent may be the same as the organic solvent added during the reaction of the chlorine-containing organopolysiloxane and the chlorine-containing organosilicon compound with ammonia or primary amine; It is only necessary to adjust the amount of this organic solvent after completion. This composition may contain various coloring agents, other organic materials, and fillers that are normally used in silicone compositions, as long as they do not decompose silazane bonds, such as silanol, alcohol, and water. It is also possible to improve the properties of the resulting coating film by adding such substances. When the curable silicone composition of the present invention is applied to a substrate, it quickly cures at room temperature to form a coating film, which has the advantage of easily adhering to various substrates. For example, silicone compositions can be used not only to bond relatively easily to glass, ceramics, aluminum, etc., but also to various plastics that conventionally could not be easily bonded without a primer, especially polycarbonate and acrylic resin. It also shows excellent adhesion to rubber and synthetic rubbers at room temperature. In addition, this coating film is based on the well-known properties of silicone.
In other words, it has excellent heat resistance, cold resistance, weather resistance, electrical insulation, mold releasability, waterproofness, and other properties, so this composition can be used as a heat-resistant insulation coating, mold release coating, waterproof coating, and abrasion resistance. It can be widely applied to various purposes such as anti-fog, anti-fouling, and dyeable coatings, and can also be used as conductive coatings, thermal conductive coatings, etc. by selecting fillers etc. Furthermore, since it has excellent adhesive properties, it can be used as a binder for various inorganic and organic powders and as a vehicle material for paints. In addition, the composition of the present invention contains ammonia,
Although amines are produced as by-products, these are extremely volatile and can be easily removed from the system, so this is not a particular problem; depending on the structure, a portion of the silazane bonds may remain in the cured film. However, this is not a problem because it has better heat resistance than siloxane bonds. Further, as mentioned above, the curable composition of the present invention exhibits rapid curing at room temperature, so it does not require the addition of a curing catalyst, but it is optional to add a condensation catalyst to accelerate curing. To accelerate curing, heating, irradiation with ultraviolet rays, electron beams, etc., or plasma treatment may be performed. Next, examples of the present invention will be given. Example 1 Formula To a mixture of 36.9 g of organopolysiloxane expressed by A product containing an organopolysiloxane represented by was obtained. Next, 20.6% by weight of this product and 79.4% by weight of methyltrichlorosilane were mixed, and 40g of this and 400ml of methylene chloride were charged into a reaction vessel and cooled to 5°C. When the gas was brought into contact with the gas for 4 hours, 463 g of a colorless and transparent solution was obtained, which was expressed by the formula It contained a methylsilazane siloxane polymer consisting of 0.25 mol% of units represented by , and 99.75 mol% of [CH ₃ Si (NH) _1.5 ] units. Next, we concentrated the amount of methylene chloride in this solution to 80% and applied it to an aluminum plate, steel plate, and acrylic resin plate to a thickness of about 10 μm using a wire bar, which cured after 60 minutes in the air. Therefore, after leaving it for another 24 hours, we investigated the physical properties of this cured film and found that it was 2mmφ in the mandrel test.
However, no cracks occurred, and according to ASTM3359,
Flexibility is 100/100 in the so-called goblin test.
It had excellent adhesion. Example 2 Tetramethyltetrachlorocyclotetrasiloxane (C1CH ₃ SiO) ₄ 53.7% by weight, methyltrichlorosilane 17% by weight, dimethyldichlorosilane 29.3%
40 g of a mixture consisting of % by weight and 300 ml of methylene chloride
was charged into a reaction vessel and cooled to 5℃, and while continuing to cool, this solution was brought into contact with ammonia gas at 20℃ or less for 4 hours, and then heated to 40-45℃ for about 30℃.
The solution was refluxed for a minute to remove the excess ammonia dissolved in it, and after cooling, the by-produced ammonium chloride was separated, yielding 395 g of a colorless and transparent solution, which was analyzed and found to be [( CH ₃ ) ₃ SiO(NH) _0.5 ] ₄ units 62.5 mol%, [CH ₃ Si
(NH) _1.5 ] unit 12.5 mol% [(CH ₃ ) ₂ SiNH] unit
It was confirmed that it was a methylsilazane siloxane polymer consisting of 25 mol%. Next, the methylene chloride concentration in this methylsilazane siloxane polymer solution was adjusted to 80% by weight,
When this was applied to an aluminum plate, a steel plate, and an acrylic resin plate in the same manner as in Example 1, these were completely cured after 60 minutes in the air.
When we examined the physical properties of this cured film after leaving it for 24 hours, we found that it showed no cracks even in a mandrel test of 2mmφ, and a score of 100/100 in a goblin test, showing excellent bending resistance,
It had excellent adhesion. Example 3 A mixture of 59.2 g of octamethylcyclotetrasiloxane and 17.0 g of tetrachlorosilane was added with stirring.
Add 1 ml of a 30% by weight solution of phosphorus nitride chloride polymer (PNC1 ₂ ) _in tetrachloroethane at 20°C, and add it at 40°C.
When the reaction was carried out under stirring for 15 hours, a chlorine-containing organopolysiloxane having an average structural formula of {C1[Si(CH ₃ ) ₂ O] ₄ } ₂ SiC1 ₂ was obtained. Next, this chlorine-containing organopolysiloxane
16.3% by weight and 83.7% by weight of methyltrichlorosilane
40 g of this and 400 ml of methylene chloride were charged into a reaction vessel and reacted with ammonia gas in the same manner as in Example 1. 470 g of a colorless and transparent solution was obtained, which was {(NH) _0.5 [Si
(CH ₃ ) ₂ O〕 ₄ } ₂ SiNH units 25 mol%, [CH ₃ Si(NH)
_1.5 ] It contained a methylsilazane siloxane polymer consisting of 75 mol% units. Next, reduce the amount of methylene chloride in this solution to 80% by weight.
When concentrated and adjusted to a thickness of approximately 10 μm on aluminum plates, steel plates, and acrylic resin plates,
This cured after 60 minutes in the air, so even more
When we examined the physical properties of this cured film after leaving it for 24 hours, we found that it showed no cracks even in a mandrel test of 2mmφ, and a score of 100/100 in a goblin test, showing excellent bending resistance,
It had excellent adhesion. Example 4 Terminal chlorine-containing dimethylpolysiloxane represented by
78.8% by weight and 21.2% by weight of methyltrichlorosilane
40g of the mixture of
Below, this solution was brought into contact with ammonia gas for 4 hours. Next, this was heated to 40-45°C and refluxed for about 30 minutes to remove the excess ammonia dissolved therein. After cooling, the by-produced ammonium chloride was separated, and 170 g of a colorless and transparent solution was obtained. Because I was given
Analysis of this material confirmed that it was a methylsilazane dimethylsiloxane polymer consisting of 80 mol% of [(CH ₃ ) ₂ SiO] ₃₀₀ units and 20 mol% of [CH ₃ Si(NH) _1.5 ] units. . Next, the methylene chloride in the methylsilazane siloxane solution obtained in this way was concentrated and adjusted to 80% by weight, and then this was applied to an aluminum plate, steel plate, or acrylic resin plate using a wire bar to thicken it. When applied to a thickness of approximately 10 μm, these were completely cured after 120 minutes in the air, forming a rubber-like cured film that adhered to each substrate, so we tested the physical properties of this cured film after leaving it for another 24 hours. However, these are all class 5 in the Goban test.
The coating film on this aluminum plate was exposed to a weather meter for 1000 hours without any discoloration or deterioration. However, for comparison, 0.5 parts of dibutyltin dilaurate as a curing catalyst was added to a mixture of 85 parts of dimethylpolysiloxane oil with an average degree of polymerization of 300 and 15 parts of methyltrimethoxysilane, in which both ends of the molecular chain were blocked with hydroxyl groups. When the curable composition was diluted with methylene chloride and applied to the same aluminum plate, steel plate, and acrylic resin plate in the same manner as above, this product formed a rubber-like cured film after about 8 hours. When the adhesion to the substrate was examined after being left for 24 hours, this cured film had poor adhesion to the substrate and easily fell off from the substrate due to friction.

Claims (1)

[Claims] 1 A molecule contains a [formula] unit and an R ² Si (NR ³ ) _3/2 unit (where R ¹ , R ² , and R ³ are hydrogen atoms or unsubstituted atoms of the same or different type) or replacement 1
a group selected from valent hydrocarbon groups, a is 1, 2,
3). B. A curable composition comprising an organic solvent. 2 The organosilazane siloxane polymer has the following general formula: [Formula] (where R ¹ is a hydrogen atom or a group selected from the same or different unsubstituted or substituted monovalent hydrocarbons, 4,0
<d<4, 0<c+d<4) One or more organopolysiloxanes and one or two organosilicon compounds having at least one silicon-halogen bond in the molecule. Claim 1 is obtained by reacting a mixture with the above with ammonia or a primary amine.
The curable composition described in .