JP5241613B2 - Adhesive for acrylic resin - Google Patents

Description

The present invention relates to a room temperature curable organopolysiloxane composition, particularly excellent in storage stability, good adhesion to synthetic resins, particularly difficult-to-adhere resins such as acrylic baths, and cracks in the cured product. ) adhesive it is possible to extend Yubisawa drying time in order to suppress the generation of (tack-free time), of the preferred room temperature curable organopolysiloxane composition or Ranaru acrylic adhesive as a sealing material.

  Room temperature curable (RTV) silicone rubber, which crosslinks with moisture, is easy to handle and has excellent weather resistance and electrical properties, so it can be used in various fields such as sealing materials for building materials and adhesives in the electrical and electronic fields. Applied.

  Particularly for general industrial use and construction use, deoxime-type RTV silicone rubbers that are well bonded to various adherends and are excellent in weather resistance are widely used. Therefore, various properties are imparted to the deoxime type RTV silicone rubber. For example, 2- (4-thiazolyl) -benzimidazole is used as a composition imparting antifungal properties used around the water in a house. A method of adding (Japanese Patent Laid-Open No. 54-127960: Patent Document 1) and a method of adding an N-substituted benzimidazolyl carbamate derivative (Japanese Patent Laid-Open No. 56-38348: Patent Document 2) are known.

  In recent years, the aesthetics of buildings has improved and the appearance has become even more important. Therefore, the technology to extend the touch drying time (tack free time) is very important from the point of view of aesthetics. Usually, trying to extend the touch-drying time (tack-free time) is to slow the curing speed, and there is an economical disadvantage in that it takes a long construction time. Therefore, it has been difficult to extend the tack free time (touch drying time) without increasing the construction time, that is, without changing the curing rate.

  On the other hand, in order to shorten the construction time, it is also important to follow the movement of the sealed joint until the sealing material is completely cured. As the method, there are proposals in Japanese Patent No. 2837658, Japanese Patent No. 2635156, and Japanese Patent Application Laid-Open No. 2001-200161 (Patent Documents 3 to 5). In Japanese Patent No. 2837658, an organic titanate compound is added. In Japanese Patent Nos. 2635156 and 2001-200161, an organic zirconium compound is added. However, a curing catalyst is added to the composition. These components are added in specific amounts in order to suppress the occurrence of cracks. Therefore, although it is possible to suppress the occurrence of cracks to some extent by using this method, at the same time, the formation speed of the cured film at the initial stage of curing, that is, the finger touch drying time (tack-free time) is easily controlled. This is impossible, and the adhesion to the resin is worsened, which may cause problems such as peeling.

  On the other hand, when an additive such as a platinum compound is added to a room temperature curable organopolysiloxane composition, it is known to use an organic solvent such as isopropyl alcohol as a solvent. The effect of extending (touch touch drying time) cannot be obtained. In addition, it is also known to use an organic solvent such as isopropyl alcohol as a dilution solvent of the room temperature curable organopolysiloxane composition, but when the deoxime type room temperature curable organopolysiloxane composition is diluted with alcohols, The characteristics of the deoxime type room temperature curable organopolysiloxane composition are impaired, and the curability and storage stability are impaired.

JP 54-127960 A JP 56-34848 A Japanese Patent No. 2837658 Japanese Patent No. 2635156 Japanese Patent Laid-Open No. 2001-200161

The present invention has been made in view of the above circumstances, it is possible to suppress the crack of acrylic resins in adhesive has good contrast, and prolongs Yubisawa drying time (tack-free time), or even cured and to provide a room temperature curable organopolysiloxane composition or Ranaru acrylic resin adhesive such.

  As a result of intensive studies to achieve the above object, the present inventors specified a secondary or tertiary alcohol in a commonly used room temperature curable one-part oxime type polysiloxane composition. By adding a certain amount, transesterification of a part of the ketoxime group of the curing agent can be carried out, and by changing to an alcohol group, adhesion to difficult-to-adhere adherends, particularly acrylic resins, can be improved, and the curing rate can be changed. It has been found that the touch drying time (tack-free time) can be extended without any problem, and the formation speed of the cured film (sealing material film) at the initial stage of curing of the sealing material can be easily controlled. Furthermore, at the same time, it has been found that the sealing material can sufficiently follow the movement of the sealed joint in the curing process and can suppress the occurrence of cracks in the sealing material due to the movement of the joint.

Accordingly, the present invention provides the following adhesive for acrylic resins.
[Claim 1]
(A) 100 parts by mass of an organopolysiloxane represented by the following general formula (1),
HO (SiR ¹ ₂ O) _n H (1)
(In the formula, R ¹ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and R ¹ may be the same or different from each other. N is an integer of 10 or more. is there.)
(B) A silane compound having two or more ketoxime groups represented by the following general formula (2) in one molecule or a partial hydrolyzate thereof 0.1 to 30 parts by mass,
R ³ _a Si (ON = CR ² ₂ ) _4-a (2)
(Wherein R ² is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, R ³ is an unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and a is 0, 1 or 2)
(C) isopropyl alcohol 0.2 to 5.0 parts by weight, and (D) surface Atsushi Muro curable ing contain fumed silica 50 parts by weight of hydrophobicized organopolysiloxane composition An acrylic resin adhesive .
[Claim 2]
The adhesive for acrylic resins according to claim 1, wherein the treating agent for hydrophobizing the fumed silica is dimethyldichlorosilane.

  According to the room temperature curable organopolysiloxane composition of the present invention, it has excellent storage stability, has good adhesion to difficult-to-adhere resins such as acrylic resins, and extends the touch drying time (tack-free time). In addition, a room temperature-curable organopolysiloxane composition that can further suppress cracks is obtained. This composition is useful as an adhesive for synthetic resin, a sealing material for building materials, which is frequently used on site.

Hereinafter, the present invention will be described in more detail. The component (A) of the room temperature curable organopolysiloxane composition of the present invention is an organopolysiloxane represented by the following general formula (1).
HO (SiR ¹ ₂ O) _n H (1)

In the above formula (1), R ¹ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, such as an alkyl such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, and an octyl group. A cycloalkyl group such as a cyclohexyl group; an alkenyl group such as a vinyl group, an allyl group, a propenyl group, a butenyl group, and a hexenyl group; an aryl group such as a phenyl group and a tolyl group; an aralkyl group such as a benzyl group and a phenylethyl group; Alternatively, a hydrogen atom of these groups is partially substituted with a halogen atom such as chlorine, fluorine or bromine, such as a trifluoropropyl group, a methyl group or a phenyl group is preferable, and a methyl group is particularly preferable. R ¹ may be the same group or a different group. Further, n in the formula (1) is an integer of 10 or more, and the viscosity of this organopolysiloxane at 25 ° C. is in the range of 25 to 500,000 mPa · s, particularly in the range of 500 to 100,000 mPa · s. Is preferred. In the present invention, the viscosity can be measured with a rotational viscometer.

Next, the component (B) is a silane compound having two or more ketoxime groups represented by the following general formula (2) in a molecule or a partial hydrolyzate thereof.
R ³ _a Si (ON = CR ² ₂ ) _4-a (2)
(Wherein R ² is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, R ³ is an unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and a is 0, 1 or 2)

Here, as R ^{2, the same} as those mentioned for R ¹ can be exemplified, and as R ³ , among those mentioned for R ¹ , unsubstituted ones are exemplified.

  Specific examples of the silane compound having two or more ketoxime groups in the molecule (B) include methyltris (dimethylketoxime) silane, methyltris (methylethylketoxime) silane, ethyltris (methylethylketoxime) silane, methyltris (methylisobutyl). Ketoxime silane, vinyl tris (methyl ethyl ketoxime) silane, vinyl tris (dimethyl ketoxime) silane, phenyl tris (methyl ethyl ketoxime) silane, phenyl tris (dimethyl ketoxime) silane, etc. These can be used alone or in combination of two or more.

  The silane compound or its partial hydrolyzate is used in an amount of 0.1 to 30 parts by weight, preferably 1 to 15 parts by weight, based on 100 parts by weight of the organopolysiloxane (A). If the blending amount is too small, sufficient crosslinking cannot be obtained, and the composition does not have the desired rubber elasticity. If the blending amount is too large, the mechanical properties are inferior.

  The secondary or tertiary alcohol of component (C) is the most important component in the present invention, and is added to impart the characteristics of the composition of the present invention. In other words, its properties can improve adhesion to difficult-to-adhere adherends, especially acrylic resins, and can easily control the formation speed of the cured film at the initial stage of curing of the composition. In this case, the movement of the sealed joint is sufficiently followed, and the occurrence of cracks in the sealing material due to the movement of the joint is suppressed.

  In the present invention, specific examples of the secondary or tertiary alcohol include secondary alcohols such as isopropyl alcohol, sec-butyl alcohol and cyclohexyl alcohol, and tertiary alcohols such as tert-butyl alcohol and tert-amyl alcohol. Isopropyl alcohol and tert-butyl alcohol are preferred. When the primary alcohol is added, the storage stability of the resulting room temperature curable organopolysiloxane composition is deteriorated. In addition, when a tertiary alcohol is added, characteristics can be obtained, but it is more preferable to use a secondary alcohol because the cost of the tertiary alcohol is high and there is a risk that the flash point is lowered and the danger is deteriorated. In particular, it is most preferable to use isopropyl alcohol.

  The blending amount of the component (C) is 0.2 to 5.0 parts by weight, preferably 1.0 to 4.0 parts by weight, particularly preferably 1 to 100 parts by weight of the organopolysiloxane of the component (A). 2 to 3.0 parts by mass. If the amount is less than 0.2 parts by mass, the above effects are insufficient. That is, adhesion to acrylic resin, formation speed control of cured coating, and joint followability are insufficient. The characteristics of the room temperature curable organopolysiloxane composition may be impaired, resulting in a delay in curing and further a poor curing.

(D) The fumed silica in which the surface of the component has been subjected to a hydrophobic treatment is an essential component for imparting appropriate reinforcing properties and rubber properties to the resulting cured product. The surface of the fumed silica to be added is preferably treated, and fumed silica whose surface is hydrophobized with reactive silane, siloxane, silazane or the like is particularly preferred. Of these, fumed silica treated with organochlorosilane, particularly dimethyldichlorosilane, is most preferred. In this case, methyltrichlorosilane, trimethylmonochlorosilane, or the like may be mixed within 50% by mass. The specific surface area (BET method) of the fumed silica is preferably 50 to 400 m ² / g, more preferably 100 to 300 m ² / g. By blending this, the physical properties such as weather resistance are remarkably improved and the tack-free time can be further improved and cracks can be suppressed.

  (D) The compounding quantity of a component is 1-50 mass parts with respect to 100 mass parts of organopolysiloxane of (A) component, It is preferable to mix | blend especially 5-30 mass parts. If it is less than 1 part by mass, the mechanical properties of the resulting cured product will be insufficient, and if it exceeds 50 parts by mass, the viscosity of the resulting composition will be too high, resulting in poor workability and dischargeability.

  A condensation catalyst may also be used to accelerate the curing of the composition. Examples of the condensation catalyst include organic tin compounds and organic titanium compounds, and organic tin compounds are preferably used.

  Examples of the organic tin compound include organic tin compounds such as dimethyldimethoxytin, dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dibenzyl malate, and dioctyltin diacetate. One of these may be used alone or two of them may be used. The above can be used in combination.

  The amount of the condensation catalyst used is generally 10 parts by mass or less, particularly 0.0001 to 5 parts by mass, and particularly preferably 0.001 to 2 parts by mass with respect to 100 parts by mass of the organopolysiloxane of component (A). If the amount of the condensation catalyst used exceeds 10 parts by mass, the initial tack-free property will be shortened and the storage stability will be degraded. May be damaged.

  In the composition of the present invention, fillers and additives generally known as optional components may be used as necessary in addition to the above components. Examples of the filler include quartz powder, titanium oxide, calcium carbonate, zinc carbonate, and talc. Additives include polyethers as thixotropy improvers, inorganic and organic antifungal agents, antibacterial agents, dimethyl silicone oil with both ends blocked with trimethylsilyl groups, silane coupling agents as adhesion aids, for example Aminosilanes such as γ-aminopropyltriethoxysilane, 3-2- (aminoethylamino) propyltrimethoxysilane, γ-glycidylpropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, etc. And epoxy silanes.

The room temperature curable organopolysiloxane composition of the present invention can be prepared by mixing the above-mentioned components by a usual method, and the obtained composition can be applied to various adherends and used as an adhesive. . In this case, various synthetic resins can be used as the adherend, and specific examples include acrylic resin, polycarbonate, PBT (polybutylene terephthalate), HIPS (high impact polystyrene) and the like. Since this invention composition is excellent in adhesiveness also to the acrylic resin made especially difficult to adhere among these, these resin can be used conveniently as a to-be-adhered body.
The composition of the present invention is particularly preferably used as a sealing material.

  The curing conditions and the like of the composition of the present invention are the same as those of this kind of known room temperature curable organopolysiloxane composition.

  The composition of the present invention has an extended touch drying time (tack free time) without changing the curing rate. Specifically, the composition is filled in an open container having an inner diameter of 10 mm, and allowed to stand (cure) at 23 ° C. and 50% RH for 1 day, and then cured by the thickness cured from the portion exposed to air. Is a touch-drying time measured according to a method defined in JIS A 5758 after molding a sheet of 2 mm thickness with a thickness of 2.4 mm or more and curing (curing) at 23 ° C. and 50% RH for 7 days. Can be 8 minutes or longer, preferably 10 minutes or longer.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

[Example 1]
15 masses of fumed silica (BET specific surface area 200 m ² / g) treated with dimethyldichlorosilane on 100 parts by mass of polydimethylsiloxane having a viscosity of 50,000 mPa · s at 25 ° C. and end-capped with silanol groups 5 parts by weight of methyltris (dimethylketoxime) silane and 1.5 parts by weight of vinyltris (dimethylketoxime) silane were added and mixed thoroughly under reduced pressure. -(Aminoethylamino) propyltrimethoxysilane 0.5 part by mass, isopropyl alcohol 1.5 part by mass, dioctyltin dioctate 0.1 part by mass were added and completely mixed under reduced pressure to obtain Sample 1.

[ Reference Example 1 ]
Sample 2 was obtained in the same manner as in Example 1, except that 1.5 parts by mass of tert-butyl alcohol was used instead of isopropyl alcohol.

[Example 2 ]
Sample 3 was obtained in the same manner as in Example 1 except that the blending amount of isopropyl alcohol was 0.5 parts by mass.

[Example 3 ]
Sample 4 was obtained in the same manner as in Example 1, except that the blending amount of isopropyl alcohol was 5.0 parts by mass.

[Comparative Example 1]
Sample 5 was prepared in the same manner as in Example 1 except that isopropyl alcohol was omitted.

[Comparative Example 2]
Instead of the isopropyl alcohol of Example 1, 1.5 parts by mass of ethanol was added and thoroughly mixed under reduced pressure to obtain Sample 6.

[Comparative Example 3]
Instead of the isopropyl alcohol of Example 1, 5.0 parts by mass of ethanol was added and thoroughly mixed under reduced pressure to obtain Sample 7.

[Comparative Example 4]
Sample 8 was obtained in the same manner as in Example 1, except that the amount of isopropyl alcohol was changed to 0.1 parts by mass.

[Comparative Example 5]
Sample 9 was obtained in the same manner as in Example 1 except that the blending amount of isopropyl alcohol was 10 parts by mass.

Table 1 shows the test results of the samples in the examples and comparative examples measured by the following method.
Test method <General characteristics confirmation test>
Measurement method for each item:
A sheet having a thickness of 2 mm was molded, and after curing at 23 ° C. and 50% RH × 7 days, the physical properties were evaluated in the following manner.
[Touch drying time (tack free time)]
It measured according to the method prescribed | regulated to JISA5758.
[Hardness, elongation at break, tensile strength]
It measured according to the method prescribed | regulated to JISK6249.

[Curing rate test]
The sample was filled in a glass petri dish having an inner diameter of 10 mm, and the thickness cured from the part exposed to air after 23 ° C. and 50% RH × 1 day was measured.

[Acrylic adhesion confirmation test]
The acrylic resin adherend having a thickness of 25 × 100 × 2 mm was coated with the compositions of Examples, Reference Examples and Comparative Examples prepared above, and allowed to stand at room temperature at 23 ° C., 50% RH × 7 days for 5 mm thickness. After forming the rubber elastic body, the adhesion of the adherend was visually confirmed by pulling the obtained cured product.
Evaluation ○: Good, Δ: Partially peeled, ×: Impossible

<Storage stability confirmation test>
Each sample was subjected to heat degradation in a dryer at 70 ° C. for 7 days under sealing, and then measured in the same manner as in the general characteristic confirmation test.

<Crack generation confirmation test>
The obtained sample was molded on an aluminum plate into a shape of width 10 mm, length 100 mm, thickness 5 mm, cured in an atmosphere of 5 ° C. or 23 ° C., 50% RH for 60 minutes, and this time passed at each temperature. The aluminum plate was bent at 90 degrees in the center, and cracks on the surface of the sealing material were confirmed.
Evaluation ○: No crack, △: Slight crack at the beginning of the sealing material, ×: Crack

Claims (2)

(A) 100 parts by mass of an organopolysiloxane represented by the following general formula (1),
HO (SiR ¹ ₂ O) _n H (1)
(In the formula, R ¹ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and R ¹ may be the same or different from each other. N is an integer of 10 or more. is there.)
(B) A silane compound having two or more ketoxime groups represented by the following general formula (2) in one molecule or a partial hydrolyzate thereof 0.1 to 30 parts by mass,
R ³ _a Si (ON = CR ² ₂ ) _4-a (2)
(Wherein R ² is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, R ³ is an unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and a is 0, 1 or 2)
(C) isopropyl alcohol 0.2 to 5.0 parts by weight, and (D) surface Atsushi Muro curable ing contain fumed silica 50 parts by weight of hydrophobicized organopolysiloxane composition An acrylic resin adhesive . The adhesive for acrylic resins according to claim 1, wherein the treating agent for hydrophobizing the fumed silica is dimethyldichlorosilane.