JP6218661B2 - Curable composition - Google Patents

Description

  The present invention relates to a curable composition capable of obtaining a cured product having excellent rubber hardness and tensile stress by being crosslinked and cured by moisture in the air while being low in viscosity before curing. .

  Conventionally, a plasticizer is added to the polymer composition in order to reduce the viscosity of the polymer composition containing the polymer and improve workability.

  Patent Document 1 discloses that (A) a modified polysulfide polymer and its curing catalyst, and (B) a modified silicone polymer and its curing catalyst as a main component, and (C) 2-propylhepta. A sealing material composition containing a phthalate ester plasticizer obtained using diol and / or 4-methyl-2-propylhexanol as a raw alcohol is disclosed, and a phthalate compound is used as the plasticizer .

JP-A-8-3537

  However, although the above sealing material composition has a low viscosity before curing due to the addition of a plasticizer and is excellent in workability, the cured product obtained by curing has a problem that the rubber hardness and tensile stress are low. ing.

  Therefore, the present invention is a curable composition that has a low viscosity before curing and excellent workability, and can be cured by crosslinking by moisture in the air to obtain a cured product having excellent rubber hardness and tensile stress. Offer things.

  The curable composition of the present invention has a hydrolyzable silyl group-containing polyalkylene oxide (A) having a number average molecular weight of 8000 to 20000, a number average molecular weight of 3000 to 6000, and a dialkoxyalkylsilyl group. 5 to 30 parts by weight of a hydrolyzable silyl group-containing polyalkylene oxide (B) having a number average of 2 or more per molecule, and a curing catalyst.

  The curable composition of this invention contains the hydrolyzable silyl group containing polyalkylene oxide (A) whose number average molecular weight is 8000-20000. The hydrolyzable silyl group possessed by the polyalkylene oxide (A) is hydrolyzed by moisture such as moisture to form a silanol group, and then the silanol groups are polycondensed by the action of a curing catalyst to form a siloxane bond. Can be formed. Thereby, a polyalkylene oxide forms a crosslinked structure, and the curable composition is cured, whereby a rubber-like elastic body is obtained. The silanol group means a hydroxy group (≡Si—OH) bonded directly to a silicon atom.

  The hydrolyzable silyl group is a group formed by bonding 1 to 3 hydrolyzable groups to a silicon atom. The hydrolyzable group of the hydrolyzable silyl group is not particularly limited, and examples thereof include a hydrogen atom, a halogen atom, an alkoxy group, an acyloxy group, an aminooxy group, and an alkenyloxy group.

  Among these, as the hydrolyzable silyl group, an alkoxysilyl group is preferable because the hydrolysis reaction is gentle. Examples of alkoxysilyl groups include trialkoxysilyl groups such as trimethoxysilyl group, triethoxysilyl group, triisopropoxysilyl group, and triphenoxysilyl group; dimethoxysilyl groups such as dimethoxymethylsilyl group and diethoxymethylsilyl group And monoalkoxysilyl groups such as a methoxydimethoxysilyl group and an ethoxydimethylsilyl group. Of these, a dialkoxysilyl group is preferable, and a dimethoxymethylsilyl group is more preferable.

  The method for introducing the hydrolyzable silyl group into the polyalkylene oxide is not particularly limited. For example, (1) a hydrosilane having a hydrolyzable silyl group is allowed to act on a polymer having an unsaturated group modified in the molecule. (2) a method of reacting a polymer having an unsaturated group in the molecule with a compound having a mercapto group and a hydrolyzable silyl group, and (3) a polymer having a functional group in the molecule. And a method of reacting a compound having a functional group reactive with this functional group and a hydrolyzable silyl group, specifically, a reaction between an isocyanate group and a hydroxyl group, an isocyanate group and an amino group, and the like. A reaction with a group, a reaction between an isocyanate group and a mercapto group, or the like can be used.

  In the hydrolyzable silyl group-containing polyalkylene oxide (A), since the curable composition is easily cured and the hardness is also easily expressed, two or more hydrolyzable silyl groups are averaged in one molecule. It is preferable to have. In the hydrolyzable silyl group-containing polyalkylene oxide (A), if the number average of hydrolyzable silyl groups in one molecule is too large, the curable composition is cured as the curing of the curable composition proceeds. Since the crosslinking density of the cured product becomes too high, the moisture permeability of the cured product decreases, and the curing of the curable composition tends to be slow and difficult to cure, so 2.0 to 4.0 is preferable, 2.0-3.0 are more preferable.

In the present invention, in the hydrolyzable silyl group-containing polyalkylene oxide, the method for measuring the number average of hydrolyzable silyl groups in one molecule is hydrolysis in polyalkylene oxide determined by ¹ H-NMR. It can be calculated based on the concentration of the functional silyl group and the number average molecular weight of the polyalkylene oxide determined by the GPC method.

  The main chain skeleton of the hydrolyzable silyl group-containing polyalkylene oxide (A) is not particularly limited. For example, polyethylene oxide, polypropylene oxide, polybutylene oxide, polytetramethylene oxide, polyethylene oxide-polypropylene oxide copolymer, Examples include polypropylene oxide-polybutylene oxide copolymer.

  When the number average molecular weight of the hydrolyzable silyl group-containing polyalkylene oxide (A) is low, the cured product of the curable composition becomes brittle, and the hardness and tensile stress of the cured product are reduced. The viscosity before curing becomes high and the workability of the curable composition decreases, so that the viscosity is limited to 8000 to 20000, preferably 8000 to 18000, and more preferably 8500 to 12000.

  In the present invention, the number average molecular weight of the polyalkylene oxide means a value in terms of polystyrene measured by a GPC (gel permeation chromatography) method. In the measurement by the GPC method, for example, Shodex KF800D manufactured by Tosoh Corporation can be used as the GPC column, and methanol can be used as the solvent.

  The curable composition of the present invention contains a hydrolyzable silyl group-containing polyalkylene oxide (B) having a number average molecular weight of 3000 to 6000 and having two or more dialkoxyalkylsilyl groups in the number average. doing.

  If the number average molecular weight of the hydrolyzable silyl group-containing polyalkylene oxide (B) is low, the cured product of the curable composition becomes brittle, and the hardness and tensile stress of the cured product are reduced. The viscosity before curing increases, and the workability of the curable composition decreases, so it is limited to 3000 to 6000, preferably 4000 to 5000.

  The main chain skeleton of the hydrolyzable silyl group-containing polyalkylene oxide (B) is not particularly limited, and examples thereof include polyethylene oxide, polypropylene oxide, polybutylene oxide, polytetramethylene oxide, polyethylene oxide-polypropylene oxide copolymer, Examples include polypropylene oxide-polybutylene oxide copolymer.

  The hydrolyzable silyl group-containing polyalkylene oxide (B) has a dialkoxyalkylsilyl group. The dialkoxyalkylsilyl group is not particularly limited, and examples thereof include a dimethoxymethylsilyl group and a diethoxymethylsilyl group. The method for introducing the dialkoxyalkylsilyl group into the polyalkylene oxide is the same as in the case of the hydrolyzable silyl group-containing polyalkylene oxide (A), and thus the description thereof is omitted.

  The hydrolyzable silyl group-containing polyalkylene oxide (B) has a number average of two or more dialkoxyalkylsilyl groups in one molecule. If the number average (average number) of dialkoxyalkylsilyl groups in one molecule of the hydrolyzable silyl group-containing polyalkylene oxide (B) is small, the curable composition is difficult to cure and the hardness is difficult to be expressed. Although it is limited to two or more, if it is too much, as the curing of the curable composition proceeds, the crosslink density of the cured product obtained by curing the curable composition becomes too high, and the moisture permeability of the cured product is increased. Is reduced, and the curing of the curable composition tends to be delayed and hard to be cured. Therefore, it is preferably 2 or more and less than 4, more preferably 2 or more and less than 3.

  When the content of the hydrolyzable silyl group-containing polyalkylene oxide (B) in the curable composition of the present invention is small, the viscosity of the curable composition before curing becomes high, and the handleability of the curable composition is improved. If the amount is decreased and the amount is too large, the curable composition is difficult to be cured.

  The curable composition of the present invention contains a curing catalyst. In the curing catalyst, the hydrolyzable silyl group contained in the hydrolyzable silyl group-containing polyalkylene oxide (A) and the dialkoxyalkylsilyl group contained in the hydrolyzable silyl group-containing polyalkylene oxide (B) are hydrolyzed. It is a catalyst for accelerating the condensation reaction between silanol groups formed.

  Curing catalysts include dibutyltin dilaurate, dibutyltin oxide, dibutyltin diacetate, dibutyltin phthalate, bis (dibutyltin lauric acid) oxide, dibutyltin bis (acetylacetonate), dibutyltin bis (monoester maleate), Tin octylate, dibutyltin octoate, dioctyltin oxide, dibutyltin bis (triethoxysilicate), bis (dibutyltin bistriethoxysilicate) oxide, dibutyltin oxybisethoxysilicate, and 1,1,3,3-tetrabutyl-1 Organic tin compounds such as 1,3-dilauryloxycarbonyl-distanoxane; and organic titanium compounds such as tetra-n-butoxy titanate and tetraisopropoxy titanate. A curing catalyst may be used independently or 2 or more types may be used together.

  If the content of the curing catalyst in the curable composition is small, the curing rate of the curable composition may be slow, and if it is large, the thermal stability of the curable composition may be decreased. 0.1-10 weight part is preferable with respect to 100 weight part of decomposable silyl group containing polyalkylene oxide (A), and 0.5-5 weight part is more preferable.

  The curable composition of the present invention preferably further contains a filler. According to the filler, it is possible to provide a curable composition capable of obtaining a cured product having excellent rubber hardness after curing.

  Examples of the filler include calcium carbonate, magnesium carbonate, calcium oxide, hydrous silicic acid, anhydrous silicic acid, finely divided silica, calcium silicate, titanium dioxide, clay, talc, carbon black, and glass balloon. These fillers may be used alone or in combination of two or more. Of these, calcium carbonate is preferably used.

  The average particle size of calcium carbonate is preferably 0.01 to 5 μm, more preferably 0.05 to 2.5 μm. By using calcium carbonate having such an average particle size, the rubber hardness and tensile stress of the cured product obtained by curing the curable composition can be improved, and as a result, the adhesive strength of the cured product is also improved. be able to.

  The content of the filler in the curable composition is preferably 10 to 500 parts by weight and more preferably 50 to 300 parts by weight with respect to 100 parts by weight of the hydrolyzable silyl group-containing polyalkylene oxide (A). If the content of the filler in the curable composition is too low, the effect obtained by adding the filler may not be sufficient. When content of the filler in a curable composition is too high, there exists a possibility that the rubber elasticity or tensile stress of the hardened | cured material which hardened the curable composition may fall.

  The curable composition of the present invention may contain other additives such as a thixotropic agent, an antioxidant, an ultraviolet absorber, a pigment, a dye, an antisettling agent, a dehydrating agent, a solvent, and an aminosilane coupling agent. .

  Antioxidants include, for example, hindered phenol antioxidants, hindered amine antioxidants, monophenol antioxidants, bis-hindered phenol antioxidants, less hindered phenol antioxidants, and polyphenol antioxidants. Examples thereof include hindered phenolic antioxidants and hindered amine antioxidants. 0.1-20 weight part is preferable with respect to 100 weight part of hydrolyzable silyl group containing polyalkylene oxide (A), and, as for content of antioxidant in a curable composition, 0.3-10 weight part Is more preferable.

  Examples of the ultraviolet absorber include benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers, and benzotriazole ultraviolet absorbers are preferred. 0.1-20 weight part is preferable with respect to 100 weight part of hydrolysable silyl group containing polyalkylene oxide (A), and, as for content of the ultraviolet absorber in a curable composition, 0.1-10 weight part Is more preferable.

  Since the curable composition of the present invention has the configuration as described above, it can be cured by ambient moisture to form a cured product having excellent rubber hardness and tensile stress.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

(Examples 1-5, Comparative Examples 1-7)
Hydrolyzable silyl group-containing polyalkylene oxide (A1) (number average molecular weight: 9000, product name “EST 280”, manufactured by Kinshi Kogyo Kagaku Co., Ltd., number average of 2.2 dimethoxymethylsilyl groups in one molecule), Hydrolyzable silyl group-containing polyalkylene oxide (A2) (number average molecular weight: 18000, product name “S3430” manufactured by Asahi Glass Co., Ltd., number average of 2.2 dimethoxymethylsilyl groups in one molecule), hydrolyzable silyl Group-containing polyalkylene oxide (B) (number average molecular weight: 4500, product name “SAX015”, manufactured by Kinshi Kogyo Kagaku Co., Ltd., number average of 2.1 dimethoxymethylsilyl groups in one molecule), polypropylene glycol (Asahi Glass Co., Ltd.) Product name “Exenol 3020”), diisononyl phthalate, acrylic compound (product name “UP-1110 manufactured by Toagosei Co., Ltd.) ), Moisture-reactive polypropylene glycol (C) (number average molecular weight: 5000, dialkoxyalkylsilyl group in number average 1.4 per molecule, trade name “SAT115” manufactured by Kinsei Industrial Chemical Co., Ltd.), colloidal carbonate Calcium (trade name “Calfine K-200M” manufactured by Maruo Calcium Co., Ltd.) and heavy calcium carbonate (trade name “Whiteon P-30” manufactured by Shiroishi Calcium Co., Ltd.) were added to the stirrer in predetermined amounts shown in Tables 1 and 2. After feeding and mixing uniformly, vacuum degassing was performed for 10 minutes. Next, a predetermined amount of organotin curing catalyst (trade name “KSF-01” manufactured by Sankyo Pharmaceutical Co., Ltd.), ethanol, dehydrating agent and aminosilane coupling agent shown in Table 1 and Table 2 are supplied to a stirrer and uniformly mixed. After mixing, defoaming was carried out under reduced pressure for 10 minutes to obtain a white paste-like curable composition.

  In Tables 1 and 2, the hydrolyzable silyl group-containing polyalkylene oxide is simply referred to as “polyalkylene oxide”.

  About the obtained curable composition, a viscosity, a tensile test, and rubber hardness were measured in the following way, and the result was shown in Table 1 and Table 2.

(viscosity)
The viscosity (Pa · s) of the curable composition before curing was measured using a B-type rotational viscometer (manufactured by Tokyo Keiki Co., Ltd.) under the conditions of 10 rpm and 23 ° C.

(Tensile test)
After coating the curable composition on a polyethylene plate so as to have a film thickness of 2.0 mm, it is cured for 7 days in an environment of 23 ° C. and a relative temperature of 50%, and the curable composition is cured and cured. A product sheet was obtained. The obtained cured sheet was extracted into a No. 3 dumbbell shape in accordance with JIS K 6251 to produce a test piece, and then a crosshead speed of 500 mm / min was used using an Instron tensile tester (manufactured by Instron Japan). The test piece was subjected to a tensile test, and the maximum tensile stress and the tensile stress (M50) when 1.5 times the original length were measured.

(Rubber hardness)
After coating the curable composition on a polyethylene plate so that the film thickness becomes 2.0 mm, the curable composition is cured for 7 days in an environment of 23 ° C. and a relative temperature of 50% to cure the curable composition. A cured product sheet was obtained. A test piece is prepared by superimposing three cured sheets, and the rubber hardness (Shore A) of the test piece is measured using a type A durometer (trade name “GS719N” manufactured by Teclock Corporation) in accordance with JIS K 6253. It was measured.

Claims (2)

100 parts by weight of a hydrolyzable silyl group-containing polyalkylene oxide (A) having a number average molecular weight of 8000 to 20000, a number average molecular weight of 3000 to 6000, and a dialkoxyalkylsilyl group in the number average of 2 A curable composition comprising 5 to 30 parts by weight of a hydrolyzable silyl group-containing polyalkylene oxide (B) having at least one and a curing catalyst. 2. The hydrolyzable silyl group-containing polyalkylene oxide (A) having a number average molecular weight of 8000 to 20000 has a dialkoxyalkylsilyl group having a number average of 2.0 or more per molecule. The curable composition according to 1.