JPH0520455B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF INDUSTRIAL APPLICATION The present invention relates to silicone compositions, in particular adhesives, which cure under ultraviolet irradiation and under the action of moisture.
The present invention relates to a silicone composition useful as a sealing material. (Prior Art) A curable silicone composition is stable under sealed conditions, but in the atmosphere, it hardens at room temperature under the action of moisture to become a rubber elastic body. So-called one-component room-temperature curable compositions and one-component UV-curable compositions that are stable under ultraviolet shielding but harden into rubber elastic bodies when irradiated with ultraviolet rays are known.
Various types of these are already known. However, when moisture-curing silicone compositions are exposed to the atmosphere, the moisture in the atmosphere permeates through and hardens from the surface, making it impossible for the surface to become rubberized in a short period of just a few seconds. UV-curable silicone compositions have the disadvantage that they cannot be used in applications that require adhesives or sealants to develop adhesive or sealing effects in a short period of time, such as adhesives or sealants. Shadow areas where it is impossible to cure and the inside of the composition colored with pigments do not harden, and especially for thick molded products, the surface layer hardens but the inside does not harden. For this reason, the present inventors first used vinylsilane having a vinyl group and a hydrolyzable group or a partial hydrolyzate thereof as a curing agent for diorganopolysiloxane in which both ends of the molecular chain are blocked with hydroxyl groups. If a mercapto group-containing organosiloxane having two mercapto groups is used, the parts that are not exposed to light will be cured by a condensation reaction between the hydrolyzable groups and moisture in the air, and the parts that are exposed to light will be cured by the vinyl groups and mercapto groups. It was discovered that the above-mentioned drawbacks could be solved because it could be cured by a photoaddition reaction with a group (Japanese Patent Application Laid-Open No. 1989-1998).
231761), but this product has a drawback in that the adhesive force immediately after irradiation with ultraviolet rays is very low, and therefore it cannot be used in applications where stress is applied to the adhesive surface after irradiation with ultraviolet rays. (Structure of the Invention) The present invention relates to a curable silicone composition that solves these disadvantages, and is characterized in that (A) at least one formula (Here, R is a monovalent saturated hydrocarbon group, a is 2 or 3, b is 1, 2 or 3, c and d are 0, 1 or 2, and b+c+d=3). 100 parts by weight of polysiloxane, (B) mercapto group per propenyloxy group of component (A)
1 in an amount of 0.1 to 20, at least 2 in the molecule
mercapto group-containing organosiloxane having 2 mercapto groups, (C) 0.01 to 10 parts by weight of photosensitizer, (D)
0.01 to 10 parts by weight of a condensation catalyst and (E) 0.01 part of a silane containing at least 3 hydrolyzable groups in the molecule.
~10 parts by weight. That is, as a result of further studies by the present inventors on curable silicone compositions that exhibit adhesive strength even immediately after irradiation with ultraviolet rays without the disadvantages mentioned above, the present inventors found that the propenyloxy group represented by the above formula (1) When the contained organopolysiloxane is reacted with a mercapto group-containing organopolysiloxane, the propenyloxy group in the organopolysiloxane as component (A) is reacted not through a siloxane bond but through a silalkylene bond such as silethylene. Since this product contains silane or siloxane containing a hydrolyzable group as component (E), it is expected that adhesive strength will be developed immediately after irradiation with ultraviolet light for several seconds to several minutes. They discovered this and completed the present invention. As described above, the organopolysiloxane as component (A) constituting the composition of the present invention has at least one compound of the above formula (1) in one molecule thereof. R is an alkyl group such as a methyl group, ethyl group, propyl group, butyl group, an aryl group such as a phenyl group or tolyl group, a cycloalkyl group such as a cyclohexyl group, or a group bonded to a carbon atom of these groups. An unsubstituted or substituted monovalent saturated hydrocarbon group having 1 to 18 carbon atoms that does not contain an unsaturated group such as a vinyl group in which some or all of the hydrogen atoms are substituted with a halogen atom, a cyano group, etc., a is 2 or 3, b
is 1, 2 or 3, c, d is 0, 1 or 2 and b
It has a group in which a propenyloxy group is bonded via a sylalkylene group, where +c+d=3, and examples thereof include the following. The organopolysiloxane as component (A) is an organosiloxane containing an unsaturated group such as a vinyl group or an allyl group, such as α,ω-divinyldimethylpolysiloxane, or an organosiloxane having a vinyl group or an allyl group in the side chain. Organopolysiloxane with linear or branched structure and general formula (b, c, d are the same as above) hydrogen silane, for example It can be easily obtained by heating and causing an addition reaction in the presence of a platinum-based catalyst. Next, since the mercapto group-containing organopolysiloxane as component (B) used in the present invention reacts with the propenyloxy group in component (A) described above when irradiated with ultraviolet rays, it forms a crosslink. , it is necessary to contain at least two mercapto groups in the molecule, and for this, the following formula

【formula】

【formula】

(Here, l is 3 or more, m, n, and p are 0 or more, and q is an integer of 2 or more). Note that the use of this mercapto group-containing organosiloxane is not limited to one type, but may be used as a mixture of two or more types, but the amount used is based on 1 propenyloxy group in component (A). If the number of mercapto groups is less than 0.1, the thickening reaction will be insufficient, and if it is more than 20, the cured product will become too hard, so it is necessary to keep the number in the range of 0.1 to 20. It is said to be 0.5 to 5 pieces. In addition, the photosensitizer as component (C) used in the present invention has a propenyloxy group in component (A) described above.
It is used to accelerate the reaction with the mercapto group in component (B) under ultraviolet irradiation, and includes acetophenone, propiophenone, benzophenone, xanthol, fluorine, benzaldehyde, anthracite, etc., which are well known in the industry. quinone,
Triphenylamine, carbazole, 3-methylacetophenone, 4-methylacetophenone, 3
-Pentylacetophenone, 4-methoxyacetophenone, 3-bromoacetophenone, 4-allylacetophenone, p-diacylbenzene, 3-
Methoxybenzophenone, 4-methylbenzophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4-chloro-4'-benzylbenzophenone, 3-chloroxanthone,
3,9-dichloroxanthone, 3-chloro-8
-nonylxanthone, benzoin, benzoin methyl ether, benzoin butyl ether, bis(4-dimethylaminophenyl) ketone, benzylmethoxyketal, 2-chlorothioxanthone, and the like. The amount of component (C) to be added is within the range of 0.01 to 10% by weight based on 100 parts by weight of component (A) present in this composition, since it is sufficient to slightly photosensitize the system. However, it is generally preferred to range from 0.05 to 2% by weight. The condensation catalyst as component (D) used in the present invention is not required when this silicone composition is cured only by ultraviolet irradiation, but is essential when it is desired to also utilize the moisture curing function. but,
This may be a known one, including lead-2-ethyl octoate, dibutyltin diacetate, dibutyltin dilaurate, butyltin tri-2-
Ethylhexoate, iron-2-ethylhexoate, cobalt-2-ethylhexoate, manganese-2-ethylhexoate, zinc-2-ethylhexoate, stannous caprylate, tin naphthenate Metallic lead of organic carboxylic acids such as tin oleate, tin butyrate, titanium naphthenate, zinc naphthenate, cobalt naphthenate, zinc stearate; tetrabutyl titanate, tetra-2-ethylhexyl titanate, triethanolamine titanate, tetra Organic titanate esters such as (isopropenyloxy) titanate; organic titanium compounds such as organosiloxytitanium and β-carbonyl titanium; alkoxyaluminum compounds; 3-aminopropyltriethoxysilane, N
- Aminoalkyl group-substituted alkoxysilanes such as (trimethoxysilylpropyl)ethylenediamine, amine compounds and their salts such as hexylamine, dodecylamine phosphate; quaternary ammonium salts such as benzyltriethylammonium acetate; potassium acetate, sodium acetate, Alkali metal lower fatty acids such as lithium oxalate; dialkylhydroxylamines such as dimethylhydroxyamine, diethylhydroxylamine; tetramethylguanidine, formula Examples include guanidyl compounds and guanidyl group-containing silanes, but the use thereof is not limited to one type, but may be used as a mixture of two or more types. Among the above-mentioned compounds, guanidine compounds and guanidyl group-containing silanes are particularly preferred because they facilitate the curing reaction and also have the function of improving adhesiveness. If the amount of this condensation catalyst used is too small relative to 100 parts by weight of the organopolysiloxane as component (A) mentioned above, curing will take a long time, and if the product is thick, it will not be possible to cure it uniformly to the depths. If the amount is too high, the skin formation time will be extremely short, causing various inconveniences on the work surface, and the resulting cured product will have poor heat resistance and weather resistance, so 0.01
-10 parts by weight, with a preferred range of 0.1 to 5 parts by weight. In addition, when the silane containing a hydrolyzable group as component (E) used in the composition of the present invention is cured by ultraviolet irradiation, the cured product exhibits adhesive properties immediately after irradiation. Examples of the hydrolyzable group include acyloxy groups such as acetoxy, octanoyloxy, and benzoyloxy groups, and ketoxime such as dimethylketoxime, methylethylketoxime, and diethylketoxime. group, methoxy group,
Alkoxy groups such as ethoxy groups and propoxy groups; alkenyloxy groups such as isopropenyloxy groups and 1-ethyl-2-methylvinyloxy groups; amino groups such as dimethylamino groups, diethylamino groups, butylamino groups, and cyclohexylamino groups; Examples include aminoxy groups such as dimethylaminoxy group and diethylaminoxy group. but,
There are no particular restrictions on this material other than that it must have at least three hydrolyzable groups as described above in its molecule, and groups other than the hydrolyzable groups may not be bonded to the silicon atom. You can leave it there. Groups other than this hydrolyzable group include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, cycloalkyl groups such as cyclopentyl group and cyclohexyl group, and alkenyl groups such as vinyl group and allyl group. , aryl groups such as phenyl, tolyl, and naphthyl groups, aralkyl groups such as 2-phenylethyl, and groups in which some or all of the hydrogen atoms of these groups are substituted with chlorine atoms, etc. Specifically, HSi( _OCH3 ) ₃ , _CH3Si ( _OCH3 ) ₃ , _CH2 =CHSi( _OCH3 ) ₃ , CH3Si(NCO) _{3 , CH2} =CHSi(NCO) ₃ , Si (NCO) ₄ , (OCN) ₃ Si-O-Si(NCO) ₃ , Examples include. In addition, this component (E) is not necessarily limited to only one type when used, and two or more types may be used in combination, but the amount used is in proportion to 100 parts by weight of component (A) above. On the other hand, if it is less than 0.01 parts by weight, the adhesive force will not be sufficiently developed immediately after irradiation with ultraviolet rays, and if it is more than 10 parts by weight, the cured product will shrink over time.
The preferred range is 0.1 to 3 parts by weight. The composition of the present invention can be obtained by uniformly mixing predetermined amounts of the above-mentioned components (A) to (E) in a dry atmosphere, and the composition thus obtained can be It has two reaction hardening properties: shrinkage hardening by minutes and hardening by ultraviolet irradiation, and adhesive strength is developed immediately after UV irradiation, so this composition can only be used for adhesives, sealants, and FIPG materials. In addition, it is suitable for use in manufacturing lines such as electrical component fixing agents and electrical coating materials. In addition, fillers may be added to the composition of the present invention for the purpose of imparting appropriate mechanical properties to the composition, and fillers include fumed silica, pyrogenic silica, precipitated silica, fumed titanium oxide, carbon black, Examples include calcium carbonate, diatomaceous earth, calcium silicate, and those treated with hydrophobization treatments such as organochlorosilanes, polyorganosiloxane, hexamethyldisilazane, etc., and the blending amount is 100 parts by weight of component (A) described above. If the amount exceeds 300 parts by weight, the fluidity of the composition will be poor and the modulus after curing will be too high.
It is preferable to use less than parts by weight. Furthermore, although the composition of the present invention is usually used as a two-component mixture, it may also be a one-component composition. This composition can also be used as a coating or primer by adding a solvent to it.
In addition, for the purpose of adjusting the properties of this composition, predetermined amounts of colorants, heat resistance, cold resistance improvers, thixotropic agents, dehydrating agents, flame retardant agents, oil resistance improvers, etc. may be added as necessary. Doing so is optional. Next, examples of the present invention will be given, in which parts are parts by weight, and viscosity is a value measured at 25°C. Synthesis Example 1 [Synthesis of component (A)] Into a four-necked glass flask equipped with a stirrer, an ester adapter reflux device, and a thermometer, a mixture with a viscosity of 8500 cS and a vinyl group weight of 0.0058 mol/100
g, α in which 10 mol% of all organic groups are phenyl groups,
ω-Divinyldimethyldiphenylpolysiloxane
Add 1,000 g of toluene and 1,000 g of toluene, heat to reflux to dehydrate, cool to room temperature, and then add 0.4 g of an isopropyl alcohol solution of chloroplatinic acid (platinum amount: 2% by weight) and 9.7 g of methyldiisopropenyloxysilane. In addition, after reacting at 70-80℃ for 3 hours, toluene was removed under reduced pressure, and the result was a transparent product with a viscosity of 10860 cS, a specific gravity of 1.035, and a refractive index of 1.4509.
990g of liquid was obtained, which was analyzed by infrared analysis.
As a result of NMR analysis, it was confirmed that it was an organopolysiloxane represented by the following formula (hereinafter abbreviated as polysiloxane A). Synthesis Example 2 Synthesis Example 1 except that the α,ω-divinylpolysiloxane in Synthesis Example 1 above was changed to α,ω-divinyldimethylpolysiloxane with a viscosity of 615 cS, and the amount of methyldiisopropenyloxysilane added was 23.7g. When treated in the same manner as above, a transparent liquid with a viscosity of 820cS, a specific gravity of 0.974, and a refractive index of 1.4057 was obtained.
990 g was obtained, and as a result of analysis, it was confirmed that this was a polysiloxane represented by the following formula (hereinafter abbreviated as polysiloxane B). Example 1, Comparative Example 1 Polysiloxane A100 obtained in Synthesis Example 1 described above
In the part, the expression 10 parts of mercapto group-containing organopolysiloxane, 10 parts of methyltriisocyanate silane
1 part, 0.5 parts of benzophenone, and 25 parts of fumed silica having a specific surface area of 200 m ² /g whose surface was silanized were added and mixed uniformly in a dry atmosphere to prepare a siloxane composition. For comparison, a composition was prepared using the same formulation as above except that methyltriisocyanate silane was not added. Next, a sheet of 120 x 120 x 2 mm was made from this composition, a sample for measuring shear adhesive strength as shown in Figure 1 was made, and a UV irradiation lamp FL20SBL360 [manufactured by Mitsubishi Electric Corporation] was used. Product name〕
The material was cured by irradiating it with ultraviolet light at an intensity of 1.5 mW/cm ² for 5 minutes, and the physical properties and shear adhesive strength of the obtained rubber elastic body were measured, and the results shown in Table 1 below were obtained. Ta.

[Table] Examples 2 to 6 Polysiloxanes A and B obtained in Synthesis Examples 1 to 2 described above were added to the formulas with the amounts shown in Table 2. Organosiloxane with a viscosity of 35cS (hereinafter abbreviated as mercaptosiloxane), or the formula organosiloxane with a viscosity of 50 cS (hereinafter abbreviated as mercaptosiloxane), tetramethylguanidylpropyltrimethoxysilane or dibutyltin dilaurate as a curing catalyst, and the formula as a sensitizer. (hereinafter abbreviated as sensitizer), (hereinafter abbreviated as sensitizer), or (hereinafter abbreviated as sensitizer), trimethoxysilane as an adhesion aid, and the specific surface area of the surface treated with silane.
Siloxane compositions were prepared by adding 200 m ² /g of fumed silica and mixing them homogeneously in a dry atmosphere (see Table 2). Next, a sheet of 120 x 120 x 2 mm and a sample for shear adhesion measurement shown in Fig. 1 were made from these compositions, and these were irradiated with ultraviolet rays in the same manner as in Example 1 or heated at 23°C. When the material was cured by being left in the atmosphere at 55% RH for 7 days and its physical properties were investigated, the results shown in Table 3 were obtained.

【table】

【table】

[Table] Examples 7 to 9, Comparative Examples 2 to 3 Polysiloxane A obtained in Synthesis Example 1 described above
In addition, the mercaptosiloxane used in Examples 2 to 6, the sensitizer, and the fourth adhesion aid.
Siloxane compositions ~XII were prepared by uniformly mixing various silanes shown in the table and fumed silica whose surface was silane-treated and having a specific surface area of 200 m ² /g in the formulation shown in Table 4 in a dry atmosphere. Next, these compositions were cured by irradiating ultraviolet rays in the same manner as in Example 1, and the physical properties of the rubber-like elastic bodies obtained were examined.
The results shown in the table were obtained.

【table】

[Table] Example 10 120×120×2 from the composition of Example 3 described above
mm sheet-like material and the sample for shear adhesive force measurement shown in Fig.
750m from UD-20-2 [product name manufactured by Nippon Battery Co., Ltd.]
When the material was cured by irradiating it with ultraviolet rays with an intensity of W/cm ² for 6 seconds and its physical properties were measured as a rubber elastic body,
The results shown in Table 6 were obtained.

【table】 [Brief explanation of the drawing]

The figure shows a perspective view of a sample for measuring shear adhesive strength used in Examples.

Claims (1)

[Claims] 1 (A) At least one formula in one molecule (R is a monovalent saturated hydrocarbon group, a is 2 or 3, b is 1, 2 or 3, c and d are 0, 1
or 100 parts by weight of an organopolysiloxane containing a group represented by b + c + d = 3 in 2; Mercapto group-containing organopolysiloxane having at least two mercapto groups in it (C) photosensitizer 0.01 to 10 parts by weight, (D) condensation catalyst 0.01 to 10 parts by weight, (E) hydrolyzable in the molecule A silicone composition comprising: 0.01 to 10 parts by weight of a silane containing at least three groups.