JPH028628B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a coating composition. More specifically, it can be stored for a long time in the absence of moisture.
The present invention relates to a coating composition that cures at room temperature in the presence of moisture and exhibits good adhesion to various substrates. In general, silicone resins have excellent heat resistance and electrical insulation properties, and are therefore widely used as base resins for heat-resistant paints and electrical insulation varnishes. However, silicone resin requires baking at high temperatures and for a long time to harden, and although it adheres well to metal plates such as mild steel plates and stainless steel plates, it does not adhere well to plastics. It has its drawbacks. The inventors of the present invention have conducted intensive studies to improve the above-mentioned drawbacks of silicone resin, and have found that it can be stored for a long time in the absence of moisture, hardens at room temperature in the presence of moisture,
Furthermore, they have discovered a coating agent that exhibits good adhesion to various base materials such as metals and plastics, and have arrived at the present invention. That is, the present invention is based on A(a) average unit formula

[Formula] (wherein, R is a monovalent organic group, X is an alkoxy group, a is a number of 0≦a≦2, b is a number of 1≦b≦4, a+
b is 1≦a+b≦4. ),
A silane or polysiloxane having at least two silicon-bonded alkoxy groups in one molecule, and (b) an epoxy resin containing at least one epoxy group and a hydroxyl group in one molecule, [component (a) Alkoxy group equivalent contained in] / [(b)
From 100 parts by weight of a silicone-modified epoxy resin having a silicon atom-bonded alkoxy group and 0.1 to 100 parts by weight of B organic titanate, which are obtained by condensation reaction under conditions such that the ratio of the equivalent amount of hydroxyl groups contained in the component is 2 or more. The present invention relates to a room temperature moisture curable coating agent composition. This coating agent composition will be explained in detail below. Component A is a condensation reaction product of the silicon-bonded alkoxy group in component (a) and the hydroxyl group in component (b), and is the main component of the composition of the present invention. (stomach)
The component is a silane or polysiloxane having at least two silicon-bonded alkoxy groups in one molecule that can undergo a condensation reaction with the hydroxyl group in the epoxy resin, and R in the formula is a silicon-bonded monovalent organic group, Alkyl groups such as methyl, ethyl, propyl and octadecyl groups, alkenyl groups such as vinyl and allyl groups, aryl groups such as phenyl and naphthyl groups, and some of the hydrogen atoms of these groups are halogen atoms, cyano groups, hydroxyl groups, mercapto groups, etc., and those in which some of the hydrogen atoms of an alkyl group are substituted with functional groups such as methacryloxy groups, acryloxy groups, glycidyl groups, and 3,4-epoxycyclohexyl groups. Illustrated. X is a silicon atom-bonded alkoxy group, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, and a methoxyethoxy group. R is 0≦a≦2
As expressed by (a), it may not be present in component (a). However, the reason why a is 2 or less and b is 1 or more and at least two silicon-bonded alkoxy groups are required in one molecule is because if there are too few alkoxyl groups, the degree of condensation with the hydroxyl group in the component (b) will decrease. less,
In addition, the amount of silicon-bonded alkoxy groups in component (A) is small, resulting in insufficient curing. From this point of view, it is preferable that at least three Xs exist in component (A). (a) The component may be silane or polysiloxane,
In the case of polysiloxane, it is sufficient if the degree of polymerization is 2 or more. The molecular shape of polysiloxane may be linear, branched, or network-like, and may contain a small amount of silicon-bonded hydroxyl group, halogen atom, or hydrogen atom. Specific examples of component (a) include methyltrimethoxysilane, methyltripropoxysilane, dimethyldiethoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, phenylmethyldiethoxysilane, and vinyltrimethoxysilane. Silane, allyltripropoxysilane, vinyltri(methoxyethoxy)silane, methylvinyldiethoxysilane, tetramethoxysilane, tetraethoxysilane, γ-chloropropyltrimethoxysilane, γ
-Chlorpropylmethyldimethoxysilane, γ-
Glycidylpropyltrimethoxysilane, γ-glycidylpropylmethyldiethoxysilane, β
(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-acryloxypropyltrimethoxysilane, one or two of these silanes There are the above-mentioned partial hydrolysis condensates, partial hydrolysis condensates of these silanes and other organosilanes, such as trimethylethoxysilane, and ethyl polysilicate. Component (b) is an epoxy resin having at least one epoxy group and hydroxyl group in one molecule, and may be bisphenol-based or novolac-based, but preferably has the following structural formula and a molecular weight of 300 to 6,000. be. Examples of commercially available epoxy resins include Epicote 815 manufactured by Ciel Chemical Co., Ltd.
There are 820, 828, 834, 864, 1001, 1004, 1007, etc. Component A is the above-mentioned component (a) and component (b), divided by [alkoxy group equivalent contained in component (a)]/[(b)
This is a silicone-modified epoxy resin having a silicon atom-bonded alkoxy group that is obtained by condensation reaction under conditions such that the ratio of hydroxyl group equivalent contained in the component is 2 or more, but when the ratio is less than 2, the component (a) and ( B) gelation tends to occur during the condensation reaction with component B), and even if gelation does not occur, gelation tends to occur when the organic titanate ester of component B, which is a curing catalyst, is blended, resulting in storage stability. do not. The larger the above ratio is, the less gelation occurs during the reaction, and the greater the storage stability when component B is blended. The condensation reaction between component (a) and component (b) is preferably carried out at 80%
This is carried out at ~250°C by adding a small amount of a conventionally known catalyst, such as an organic titanate. When carrying out this condensation reaction, an organic solvent may be used to dissolve components (a) and (b), but some substrates may not like organic solvents, so in such cases, It is desirable to carry out the reaction with an excess of low boiling point alkoxysilane. Component B is a catalyst that makes component A curable under room temperature humidity, and specific examples include titanic acid of monohydric alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, cyclohexyl alcohol, octyl alcohol, and octadecyl alcohol. There are titanate esters of dihydric alcohols such as esters, ethylene glycol, propylene glycol, octylene glycol, diethylene glycol, triproprene glycol, and tetraethylene glycol, and titanate esters of trihydric alcohols such as glycerin. If the amount of component B added is too small, curing will be slow and workability will be reduced, and if it is too large, the cured film will become brittle and cracks will easily form. to 100 parts by weight. From the viewpoint of curability, adhesion to substrates, and storage stability, the amount is preferably 5 to 90 parts by weight. In order to obtain the coating agent composition of the present invention from component A and component B, it is sufficient to simply mix them. However, in order to increase storage stability, they may be mixed in the absence of moisture or deaerated after mixing. Preferably, it is stored in a moisture-impermeable container. In the coating agent composition of the present invention, component (a), component (b), or both may remain as long as the object of the present invention is not impaired. Agents, pigments, and heat-resistant agents may also be added. In particular, organotrialkoxysilane, which is a type of component (A), is 5 parts by weight per 100 parts by weight of component A.
It may be actively added so that it is present in an amount of up to 500 parts by weight. The organic group in this organotrialkoxysilane is the same as the above-mentioned R, and the alkoxy group is the same as the above-mentioned X. The coating agent composition of the present invention can be stored for a long time in the absence of moisture, hardens even at room temperature in the presence of moisture, and is tough and heat resistant.
It forms a film with excellent weather resistance and firmly adheres to various metals, plastics, wood, and other substrates, making it extremely useful as a protective coating for these substrates. Next, examples of the present invention are listed, and in the examples, "parts" means parts by weight. Further, dry-to-touch time, adhesion and pencil hardness were measured under the following conditions. Dry-to-touch time: The dry-to-touch time was defined as the time it took for the coating surface to become non-adhesive and fingerprint-free after coating the base material. Pencil hardness: Measured according to JIS K 5400. Adhesion (goban test): Cut 100 1 mm square squares in a 1 cm square square, paste commercially available cellophane tape on top of it, and suddenly peel it off. It shows how many of them remained on the base material. The number of remaining squares is the numerator,
Write down the number of squares you cut in the denominator. Example 1 Epicote 1001 manufactured by Ciel Chemical Co., Ltd. and methyltrimethoxysilane were subjected to a condensation reaction with the composition shown in Table 1. At this time, tetrabutyl titanate was added as a condensation reaction promoting catalyst, and toluene was used as a solvent. These raw materials were charged into a three-necked flask equipped with a reflux condenser, a thermometer, and a stirring device, and reacted for 5 hours in a reflux state at 90°C. After the reaction, low-boiling substances are distilled off and the temperature is lowered.
A pale yellow transparent silicone-modified epoxy resin containing silicon-bonded methoxy groups was obtained. these resins 20
When 2 parts of tetrabutyl titanate was added to 1 part of tetrabutyl titanate, the ratio of methoxy group equivalent to hydroxyl group equivalent was 1.
Regarding sample No. 3 using sample No. 1 below,
Samples that gelled immediately but had the same ratio of 6.9
Regarding sample No. 4 using No. 2, no increase in viscosity was observed, and when it was stored in a glass bottle tightly sealed, it maintained a uniform liquid state even after 3 months. Furthermore, when the composition of Sample No. 4 containing tetrabutyl titanate was applied to a stainless steel plate at room temperature, the coating surface became non-adhesive within 10 minutes and adhered well to the stainless steel plate.

【table】

【table】

[Table] Note) Time taken until the coating surface becomes non-adhesive and no longer leaves fingerprints Example 2 Epicoat 1001 450 manufactured by Ciel Chemical Co., Ltd.
(hydroxyl group equivalent: 1.44), 1050 parts of methyltrimethoxysilane (methoxy group equivalent: 23.2), and 0.1 part of tetrabutyl titanate were charged into a 200 ml three-necked flask equipped with a reflux condenser, a thermometer, and a stirring device. While stirring, the temperature was gradually raised until a reflux state was reached. Since a reflux state was reached at about 88°C, the reaction was continued in this state for 5 hours. After the reaction, 108 parts of low-boiling substances were distilled off,
A pale yellow transparent silicone-modified epoxy resin containing silicon-bonded methoxy groups with a non-volatile content of 37.7%.
Obtained 1390 copies. Calculating from the solid content, the silicone-modified epoxy resin contains about 14% by weight of silicone. Note that the volatile content in the reaction residue is the raw material methyltrimethoxysilane. Five types of compositions were prepared by blending this silicone-modified epoxy resin, methyltrimethoxysilane, and tetrabutyl titanate as shown in Table 3. These compositions were applied to a stainless steel plate (SUS 304), a methacrylic resin plate, and a polycarbonate resin plate. Touch dry time and 48
Adhesion (goban test) and pencil hardness after curing at room temperature for hours were evaluated. The results are shown in Table 3.
From this, if the amount of tetrabutyl titanate added is too small, it will take a long time to dry, and if it is too large, the film will become moldy and prone to cracks, resulting in poor adhesion to methacrylic resin plates and stainless steel plates. It can be seen that this decreases.

[Table] Example 3 A coating agent composition was obtained by blending 260 parts of methyltrimethoxysilane and 26 parts of tetrabutyl titanate with 100 parts of the silicone-modified epoxy resin solid content of Example 2. This was coated on the various substrates shown in Table 4, left to stand at room temperature for 48 hours to cure, and then the adhesion to these substrates and coating hardness were examined, and the results are shown in Table 4.

【table】

[Table] Note) Example 4 of liquid polyurethane resin paint for curtain walls manufactured by Dainippon Toyo Co., Ltd. (1) Synthesis of silicone-modified epoxy resin After hydrolyzing and condensing methyltrimethoxysilane under an acid catalyst, , 144 parts of methylmethoxypolysiloxane (methoxy group equivalent: 1.39) having a viscosity of 42 centistokes at 25°C and a methoxy group content of 30% by weight, obtained by distilling off low-boiling substances;
Epicote 1001 576 manufactured by Ciel Chemical Co., Ltd.
(OH group equivalent: 1.84), 0.2 parts of tetrabutyl titanate, and 1080 parts of toluene were charged into a 2000 ml three-necked flask equipped with a stirrer, a reflux condenser, and a thermometer. The temperature was gradually raised to 105°C, and stirring was continued while methanol produced at this temperature was distilled off, and the reaction was carried out until compatibility was achieved. (Compatibility was determined by taking a sample every hour on a glass plate and evaporating the solvent, and the point at which the obtained film became transparent was determined to be compatible.) After compatibility was achieved, low boiling point 300
After distilling 1 ml, the temperature was lowered to 80°C. Methyltrimethoxysilane when the temperature drops below 80℃
138 parts (methoxy group equivalent: 3.03) were charged. In addition, the ratio of total methoxy group equivalent/hydroxyl group equivalent is:
It was 2.4. The temperature of this mixture was gradually raised, and the reaction was carried out in a reflux state for 6 hours. After the reaction, the temperature was lowered to obtain a transparent liquid silicone-modified epoxy resin with a nonvolatile content of 43%. (2) Preparation of coating agent composition and adhesion to various substrates 100 parts of silicone-modified epoxy resin solids, 230 parts of methyltrimethoxysilane, and tetrabutyl titanate or this composition were applied to stainless steel plates, mild steel plates, and polycarbonate. Apply to resin board, methacrylic resin board and leave at room temperature for 48 hours.
After being left to cure for a period of time, the adhesion was examined by a cross-cut test. Both showed good adhesion with a rating of 100/100. The coating agent composition did not increase in viscosity even when it was sealed in a glass bottle and stored at room temperature for 3 months.

Claims (1)

[Claims] 1 A(a) Average unit formula [Formula] (In the formula, R is a monovalent organic group, X is an alkoxy group, a is a number of 0≦a≦2, and b is 1≦b≦ 4, a+b is 1≦a+b≦4), and has at least two silicon-bonded alkoxy groups in one molecule; An epoxy resin containing one epoxy group and a hydroxyl group is prepared by [(a) equivalent of alkoxy group contained in component]/[(b)
From 100 parts by weight of a silicone-modified epoxy resin having a silicon atom-bonded alkoxy group and 0.1 to 100 parts by weight of B organic titanate, which are obtained by condensation reaction under conditions such that the ratio of hydroxyl group equivalent contained in the component is 2 or more. A room temperature moisture curable coating agent composition.