JPH0530876B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a surface-curing organopolysiloxane composition, and more specifically, it has storage stability under moisture-blocking conditions, and when cured by atmospheric moisture, the surface becomes a rubber-like elastic body. The present invention relates to a surface-curing organopolysiloxane composition that is cured and remains uncured or semi-cured internally. [Prior Art] An organopolysiloxane whose molecular chain ends are blocked with hydroxyl groups is reacted with an amide group-containing organosilicon compound and/or an aminoxy group-containing organosilicon compound as a curing agent, and the entire composition is heated at room temperature. Methods for curing rubber-like elastic bodies are known.
This composition contains a difunctional compound and a trifunctional compound as a curing agent.
By using a polyfunctional compound with higher functionality and changing the ratio, it is possible to change the physical properties over a wide range from low modulus and high elongation to high modulus and low elongation. In particular, low modulus and high elongation type compositions are widely used as architectural sealants due to the excellent weather resistance and fatigue resistance of organopolysiloxanes. In addition, it is made of organopolysiloxane whose molecular ends are blocked with hydroxyl groups, silicon compounds containing aminoxy groups, and alcohol compounds, and although the surface hardens and changes into an elastic body, the inside remains unhardened and in good condition. Compositions that exhibit excellent adhesion are also known (see JP-A-56-86951). [Problems to be Solved by the Invention] However, among the above compositions, the former composition using an amide group-containing organosilicon compound as a curing agent has insufficient adhesion to various substrates. Ta. Furthermore, the latter composition using an aminoxy group-containing silicon compound and an alcohol compound has poor storage stability, and is extremely difficult to apply as a one-pack type sealing material composition. Therefore, when using this as a sealant, store the organopolysiloxane whose molecule ends are blocked with hydroxyl groups and the aminoxy group-containing silicon compound as a hardening agent in separate containers, and use them as a sealant. There were problems in that a method of mixing immediately before use had to be adopted, the handling method was complicated, and the manufacturing cost was disadvantageous. The present inventors conducted studies to solve these drawbacks, and as a result, they arrived at the present invention. An object of the present invention is to provide a composition with excellent storage stability, which has a rubber-like elastic surface after curing, and
The object of the present invention is to provide a one-pack type surface-curing sealant composition that maintains an uncured or semi-cured state inside and has excellent adhesiveness and durability. [Means for solving the problems and their effects] The above purpose is to prepare (A) 100 parts by weight of an organopolysiloxane having a viscosity of 20 to 1,000,000 centipoise at 25°C and whose molecular chain ends are blocked with hydroxyl groups. A mixture of an organosilicon compound having an amide group and an organosilicon compound having three or more amide groups, or an organosilicon compound having two amide groups and an organosilicon compound having three or more aminoxy groups A mixture in which the proportion of the organic silicon compound having an amide group in the mixture is 50% by weight or more 1 to 20 parts by weight (C) An organic compound having one hydroxy group (Component (C)) This can be achieved by a one-pack type surface-curing sealant composition characterized in that the weight ratio of (B) to component (B) is from 0.001 to 0.5. Component (A) used in the present invention is the main material of the present composition, and has the general formula HO[-R ¹ ₂ SiO]-nH (wherein R ¹ is the same or different substituted or unsubstituted is a substituted monovalent hydrocarbon group, and n is the viscosity of the organopolysiloxane at 25°C.
α,ω-dihydroxy-organopolysiloxanes having a value of 20 to 1,000,000 centipoise) are preferably used. However, it is also possible to use a form in which a part of the linear chain is branched and the number of hydroxyl groups in one molecule is three or more.
R ¹ is a methyl group, an ethyl group, a propyl group,
Alkyl groups such as octyl; alkenyl groups such as vinyl and allyl; aryl groups such as phenyl and tolyl; halogens such as chloromethyl, cyanoethyl, and 3.3.3-trifluoropropyl Examples include hydrogenated hydrocarbon groups, but 70% or more of R ¹ is methyl groups due to ease of synthesis, balance between required mechanical properties after curing and appropriate viscosity of the uncured composition. is preferable, and more preferably all of R ¹ are methyl groups. If the viscosity of the organopolysiloxane at 25° C. is less than 20 centipoise, it will not be possible to impart excellent physical properties to the rubber-like elastomer after curing, especially flexibility and high elongation. Also,
When it is larger than 1,000,000 centipoise, the viscosity of the composition becomes high, and workability during construction becomes extremely poor. Therefore, a range of 20 to 1,000,000 centipoise is selected, more preferably a range of 200 to 200,000 centipoise. The organosilicon compound as the component (B) used in the present invention is a curing agent for crosslinking and curing by reacting with the hydroxyl group of the organopolysiloxane as the component (A) in the presence of moisture at room temperature. A mixture of an organosilicon compound having 3 amide groups and an organosilicon compound having 3 or more amide groups, or a mixture of an organosilicon compound having 2 amide groups and an organosilicon compound having 3 or more aminoxy groups. It is a mixture with elementary compounds. Examples of such organosilicon compounds having two amide groups include dimethylbis(N-methylacetamido)silane, dimethylbis(N-ethylacetamido)silane, methylvinylbis(N-methylacetamido)silane, and methylvinylbis(N-methylacetamido)silane. Amidosilanes such as bis(N-butylacetamido)silane, amidosiloxanes such as Examples include amidocyclosiloxanes such as. Examples of organosilicon compounds having three or more amide groups include amidosilanes such as methyltris(N-phenylacetamido)silane, vinyltris(N-ethylacetamido)silane, and tetrakis(N-methylacetamido)silane; amidopolysiloxanes such as Amidocycloxanes such as are exemplified. Examples of organosilicon compounds having three or more aminoxy groups include methyltris(diethylaminoxy)silane, Aminoxysilanes such as Si[ONC(C ₂ H ₅ ) ₂ ] ₄ , aminoxypolysiloxanes such as Examples include aminoxycyclosiloxanes such as. Organosilicon compounds containing both an amide group and an aminoxy group in one molecule can also be used, but are usually not used due to difficulty in synthesis and cost. In the present invention, an organosilicon compound containing two amide groups in one molecule and an organosilicon compound containing three or more amide groups or aminoxy groups in one molecule are used in an appropriate mixture. However, the proportion of the amide group-containing organosilicon compound in component (B) is 50% by weight or more. There is no particular limitation on how the functional numbers of the amide group and the functional number of the aminoxy group are combined, but it is necessary to achieve low stress and high elongation, or to improve storage stability when packaged in one package. Due to its properties, etc., the one with higher reaction activity is used as the bifunctional component. In general, amide group-containing organosilicon compounds have higher reactivity than aminoxy group-containing organic compounds;
An amide group-containing organosilicon compound is used as the functional component, and an amide group-containing organosilicon compound or an aminoxy group-containing organosilicon compound is used as the trifunctional or more functional component. In order to more effectively achieve the object of the present invention where the surface is cured into a rubber-like elastic body and the interior is uncured or semi-cured (hereinafter referred to as mastic properties), an amide group-containing organic silicone is used as a bifunctional component. It is preferable to use an organic silicon compound containing an aminoxy group as the trifunctional or higher functional component. The reason for limiting the functional groups of component (B) to compounds having two amide groups and three or more amide groups or aminoxy groups is that in order for the cured composition to exhibit sufficiently low stress and high elongation, In addition, in order to provide mastic properties, which is the object of the present invention, these functional groups need to easily react with the compound of component (C) at room temperature. If the amount of component (B) added is too small, the surface will not harden or the storage stability will be poor when packaged in one package, and if it is too large, the curing property will be poor and it may be economically difficult. Since this is disadvantageous, the amount is in the range of 1 to 20 parts by weight per 100 parts by weight of the organopolysiloxane (A). Component (C) used in the present invention is an organic compound having one hydroxyl group, and is an important component for achieving the mastic properties aimed at in the present invention.
If component (C) is not added, the entire body will crosslink and harden into a rubber-like elastic body, but if component (C) is added, only the surface that comes into contact with the atmosphere will harden into a rubber-like elastic body. However, the inside remains uncured or semi-cured. This is due to the reaction between component (B), a part of the amide group or aminoxy group of the organosilicon compound having an amide group or an organosilicon compound having an aminoxy group, and component (C), which transforms into a compound with low curing activity. This is thought to be due to a mixture of these factors. This reaction is shown, for example, by the following reaction formula. An organic compound having one hydroxy group is typified by a monohydric alcohol compound, and is represented by the general formula R-OH (wherein R is a substituted or unsubstituted monovalent hydrocarbon group). R is preferably selected from saturated aliphatic monovalent hydrocarbon groups, unsaturated aliphatic monovalent hydrocarbon groups, alicyclic monovalent hydrocarbon groups, and substituents thereof such as halogen atoms, cyano groups, alkoxy groups, etc. . Of course, the monohydric alcohol compound includes all isomers. Specific examples include methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, and octyl alcohol. Saturated aliphatic alcohols such as lauryl alcohol, stearyl alcohol, butycellosolve, diethylene glycol monomethyl ether, allyl alcohol, crotyl alcohol (2-buten-1-ol), allyl carbinol (3-buten-1-ol), propargyl alcohol , methylbutynol, unsaturated aliphatic alcohols _{such as} HC≡CC( _CH3 ) _2OCH2CH2OH , 2.2-dibromoethanol,
2.2.2-trifluoroethanol, 1.1.1-trichlor-2-propanol, 2.2.3-trichlor-
halogen-substituted alcohols such as 1-butanol,
Examples include alicyclic alcohols such as cyclohexanol. When using one of these compounds having a melting point above room temperature, it may be used after being dissolved in a small amount of an organic solvent. The amount of component (C) added varies depending on the molecular weight, activity of the functional group, and amount added of component (B), and the molecular weight, activity of the functional group, and method of addition of component (C). (B)
A weight ratio of 0.001 to 0.5 for the components is used. In addition to components (A) to (C), the composition powder of the present invention contains fine powder in order to improve the flow characteristics before curing and to impart the mechanical properties necessary as a sealant after curing. Preferably, an inorganic filler is added. Examples of inorganic fillers include fumed silica, calcined silica, precipitated silica, fine quartz powder, calcium carbonate, titanium oxide, diatomaceous earth, aluminum hydroxide, alumina, and silanes,
There are products whose surface has been treated with silazane, low polymerization degree siloxane, organic compound, etc. When used as a building sealant, especially when low stress and high elongation are required, calcium carbonate is preferably used. Furthermore, an organic solvent, a pigment, a fungicide, a flame retardant, a plasticizer, a thixotropic agent, an adhesion promoter, etc. can be added to the composition of the present invention, if necessary. The composition of the present invention can be easily obtained by mixing component (A), component (B), and component (C) in advance at the time of manufacture and packaging them in one package. Since the composition of the present invention is packaged in one package, it is easy to handle and can be suitably used as a building sealant.
It is useful as a mastic-type sealant by taking advantage of the characteristics that the surface hardens into a rubber-like elastic body and the inside remains unhardened or semi-hardened. [Example] The present invention will be explained below using Examples. In the examples, all parts indicate parts by weight. In addition, the following abbreviations were used in the examples. M ₁₅₀ : 150% tensile stress, Tmax: maximum tensile stress, Emax: elongation at maximum load, CF: cohesive failure, AF: adhesive failure, Example 1 α with a viscosity of 12000 centipoise at 25°C,
100 parts of ω-dihydroxydimethylpolysiloxane,
25 parts of light calcium carbonate and 115 parts of heavy calcium carbonate were mixed until homogeneous. To this mixture were added 8 parts of dimethylbis(N-methylacetamido)silane, 3 parts of an aminoxy group-containing organosilicon compound represented by the following formula and a compound having a hydroxy group shown in Table 1 were added and mixed until homogeneous to obtain a sealant composition. Using this composition, JIS-
An H-type joint (adherent mortar, no primer) specified in A5758 was prepared. After being left at room temperature for two weeks to cure, its physical properties were measured.
The measurement results were as shown in Table 1. The surfaces of the sealant compositions of the present invention exhibited rubber-like elasticity after curing, and the interiors were in a semi-cured state. Furthermore, as a result of putting these sealant compositions in polyethylene containers, sealing them, and examining their storage stability under wet shut-off conditions, there was no increase in viscosity even after storage for 6 months, indicating that the compositions were excellent. It showed storage stability. Furthermore, for comparison, Table 1 also shows the results of evaluation of a composition obtained by the same method as above except that no compound having a hydroxyl group was added.

〔Effect of the invention〕

The one-pack type surface-curing sealant composition of the present invention is a mixture of an organosilicon compound having a specific amide group as a component (A), an organosilicon compound having a specific amide group as a component (B), and an organic silicon compound having a hydroxy group as a component (C). Since it is a one-pack type surface-curing sealant composition consisting of a compound, it has excellent storage stability before curing, and after curing, it has excellent adhesion to various substrates and has a rubber-like elastic surface. It has the characteristic that it can be used as a sealing material whose interior remains uncured or semi-cured.

Claims (1)

[Scope of Claims] 1 (A) 100 parts by weight of an organopolysiloxane having a viscosity of 20 to 1,000,000 centipoise at 25°C and whose molecular chain ends are blocked with hydroxyl groups, (B) an organosiloxane having two amide groups; consisting of a mixture of an elementary compound and an organosilicon compound having three or more amide groups, or a mixture of an organosilicon compound having two amide groups and an organosilicon compound having three or more aminoxy groups, A mixture in which the proportion of the organosilicon compound having an amide group in the mixture is 50% by weight or more, 1 to 20 parts by weight, (C) an organic compound having one hydroxy group (B) component of the (C) component 1. A one-pack type surface-curing sealant composition, characterized in that the composition comprises an amount such that the weight ratio to 2 Component (A) has a viscosity of 200 to 200,000 at 25℃
The composition of claim 1 which is a centipoise α,ω-dihydroxy-dimethylpolysiloxane. 3. The composition according to claim 1, wherein component (C) is an alcohol compound represented by the general formula R-OH (wherein R is a substituted or unsubstituted monovalent hydrocarbon group) .