JP2543721B2 - Adhesion promoter - Google Patents

Description

TECHNICAL FIELD The present invention relates to an adhesion promoter that promotes the adhesiveness of a curable organopolysiloxane composition. More specifically, it relates to an adhesion promoter that promotes adhesion by being added to a curable organopolysiloxane composition or undercoated on a substrate.

[Prior Art] Conventionally, many compounds that promote the adhesiveness of a curable organopolysiloxane have been proposed (Japanese Patent Publication No. 52-4814).
No. 6, JP-B-55-21782, JP-B-55-39258, JP-A-54-91159, etc.). Among them, organopolysiloxanes having an epoxy group, an alkoxy group and an alkenyl group as described in JP-B-52-48146 or JP-B-55-21782 are known to those skilled in the art as those which promote good adhesiveness. Has been.

[Problems to be Solved by the Invention] However, these conventional techniques have various problems. A mere dealcohol reaction product of an organopolysiloxane having an alkenyl group and a silanol group described in JP-B-52-48146 and an epoxy group-containing trialkoxysilane, or an alkenyl described in JP-B-55-21782. The reaction product of an organopolysiloxane having a silane group and a silanol group with an epoxy group-containing trialkoxysilane at low temperature has a drawback that the obtained organopolysiloxane has insufficient stability and cannot be produced with good reproducibility. was there. Further, since the alkoxy group of the epoxy group-containing trialkoxysilane is crushed by the condensation reaction with the silanol group, there is a drawback that the amount of the alkoxy group which is thought to play an important role in adhesion is reduced.

The present invention aims to eliminate the above-mentioned drawbacks of the prior art, and provides an adhesion promoter having excellent reproducibility of adhesive properties.

[Means for Solving Problems and Actions Thereof] The above-mentioned objects are the unit represented by the formula R ¹ SiO _3/2 , the unit represented by the formula R ¹ R ² aSiO _{(3-a) / 2} , and the formula R ^{2 _{bR 3 cR 4 dSiO (4-}} b-c-d) / 2 units and wherein R ³ represented by _{^{eR 4 fSiO (4-e-}} f) / 2 is a main agent of an organopolysiloxane consisting of units represented by adhesive Accelerator (in the formula, R ¹ is a monovalent organic group having an epoxy group, R ² is an alkoxy group, R ³ is a monovalent hydrocarbon group excluding an alkenyl group, R ⁴ is an alkenyl group, and a and b are 1 Or 2, c, d, e and f are numbers of 2 or less, e + f is a number of 1 or more, the ratio of R ^{1 to} all organic groups is 2 mol% or more, and
The ratio of R ² is 5 mol% or more, and the ratio of R ^{4 to} all organic groups is 2 mol% or more).

To explain this, the organopolysiloxane used in the adhesion promoter of the present invention has an epoxy group, an alkoxy group and an alkenyl group at the same time, and has the unit of the formula R ¹ SiO _3/2 , the formula R ^{1 A unit represented by 1} R ² aSiO _{(3-a) / 2} , a unit represented by the formula R ² bR ³ cR ⁴ aSiO _{(4-b-cd) / 2} , and a formula R ³ eR ⁴ fSiO _(4-e) It is composed of the unit represented by _{-f) / 2} .

In the above formula, R ¹ is a monovalent organic group having an epoxy group, which includes a 3-glycidoxypropyl group, a glycidoxymethyl group, and 2- (3,4-epoxycyclohexyl).
An ethyl group is exemplified. R ² is an alkoxy group, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, and a methoxyethoxy group, and a methoxy group is more preferable from the viewpoint of adhesiveness. R ³ is a monovalent hydrocarbon group excluding alkenyl group, which includes alkyl groups such as methyl group, ethyl group, propyl group, butyl group, and hexyl group; aryl groups such as phenyl group, tolyl group, and xyl group. Group; exemplified by aralkyl groups such as benzyl group and phenethyl group,
From the economical viewpoint and the compatibility with the curable organopolysiloxane composition to which the adhesion promoter of the present invention is applied, a methyl group or a phenyl group is more preferable. R ⁴ is an alkenyl group, and examples thereof include a vinyl group, an allyl group, a propenyl group, a butenyl group, a pentenyl group, a hexenyl group and a decenyl group.

The ratio of R ^{1 to} all organic groups in the organopolysiloxane is 2 mol% or more, which is 2
This is because an adhesive force with good reproducibility cannot be obtained if the amount is less than the molar percentage. The ratio of R ^{2 to} all the organic groups is 5 mol% or more, because if it is less than 5 mol%, good adhesive force cannot be obtained. The ratio of R ^{4 to} the total organic groups is 2 mol% or more, because if it is less than 2 mol%, good adhesive force cannot be obtained. R ¹ SiO in organopolysiloxane
_{The 3/2} unit has the effect of improving the reproducibility of adhesive properties.

The organopolysiloxane which is the main component of the adhesion promoter of the present invention includes, for example, organosilane having an alkoxy group and an epoxy group, and organopolysiloxane having an alkenyl group, potassium hydroxide, sodium hydroxide and lithium hydroxide. Alkali metal hydroxides such as cesium hydroxide; alkali metal alcoholates, alkali metal silanolates of dimethylpolysiloxane and methylphenylpolysiloxane, amines, basic catalysts of ammonium hydroxide such as tetramethylammonium hydroxide. It is obtained by carrying out an equilibration reaction in the presence. Here, as the organosilane having an epoxy group and an alkoxy group, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3,4-epoxycyclohexyltrimethoxysilane, 3,4- Examples include epoxycyclohexyltriethoxysilane and glycidoxymethyltrimethoxysilane.

As the polysiloxane having an alkenyl group, a methylalkenylpolysiloxane having both ends hydroxyl group blocked, a methylalkenylpolysiloxane having both ends trimethylsiloxy group blocked, a methylalkenylsiloxane-dimethylsiloxane copolymer having both ends hydroxyl group blocked, both ends Examples thereof include a trimethylsiloxy group-blocked methylalkenylsiloxane-dimethylsiloxane copolymer, a both-end hydroxyl group-blocked methylalkenylsiloxane-diphenylsiloxane copolymer, a cyclic methylalkenylpolysiloxane, and a cyclic methylalkenylsiloxane-dimethylsiloxane copolymer.

The adhesion promoter thus obtained can be added to any type of curable organopolysiloxane composition to promote the adhesion of the composition. Such a curable organopolysiloxane composition may be, for example, an addition reaction type curable organopolysiloxane composition, a dealcoholization reaction type curable organopolysiloxane composition, a deoxime reaction type curable organopolysiloxane composition, or a deoxidized reaction type curable organopolysiloxane composition. Acetic acid reactive curable organopolysiloxane composition, deacetone reactive curable organopolysiloxane composition, deamine reactive curable organopolysiloxane composition, peroxide curable organopolysiloxane composition, high energy ray curing Type organopolysiloxane composition, and the addition reaction type curable organopolysiloxane composition is particularly effective. Further, the adhesion promoter of the present invention may be used as a primer for adhesion (primer).

Further, other components may be used in combination, and other components include organoalkoxysilanes, silane coupling agents, alkoxy compounds or chelate compounds of metals such as titanium, tin and aluminum, diorganopolysiloxane and organic solvents. .

[Examples] The present invention is described below with reference to Examples. During implementation,
"Parts" means "parts by weight" and "percent"
Alternatively, "%" means "weight percent". The characteristics are measured at 25 ° C unless otherwise specified. In the formula, Me represents a methyl group and Vi represents a vinyl group.

Example 1 A four-necked flask equipped with a stirrer, a thermometer and a reflux condenser was charged with 107 parts of tetramethyltetravinylcyclotetrasiloxane, 91 parts of 3-glycidoxypropyltrimethoxysilane and 0.15 part of potassium hydroxide. And heated with stirring. After reacting at a temperature of 120 ° C. for 3 hours, it was neutralized with dimethyldichlorosilane, and low-boiling substances were distilled off by vacuum distillation at 120 ° C. and 5 mmHg. The obtained organopolysiloxane was analyzed by infrared spectroscopy (IR), Fourier transform nuclear magnetic resonance analysis (FTNMR) and gel permeation chromatography (GPC), and was found to have the following average formula.

[RSiO _3/2 ] _0.09 (wherein R is 3-glycidoxypropyl group) This organopolysiloxane was designated as A-1.

Further, organopolysiloxanes A-2 and A-3 were produced in exactly the same manner except that another lot of tetramethyltetravinylcyclotetrasiloxane and 3-glycidoxypropyltrimethoxysilane were used (the organopolysiloxane obtained was still obtained). The average formula of
Was exactly the same).

Average molecular weight of dimethylvinylsiloxy groups blocked at both ends 11
100 parts of dimethylpolysiloxane of 000, dry silica whose surface is treated with hexamethyldisilazane (specific surface area 200 m
² / g) 20 parts, 0.15 parts of a 2% isopropyl alcohol solution of chloroplatinic acid, 3-methyl-1-butyn-3-ol 0.01
Molecular weight of trimethylsiloxy group blocking at both ends
3 parts of dimethylsiloxane methylhydrogen copolymer (700: molar ratio of dimethylsiloxane and methylhydrogensiloxane: 3/5), which is 700, was mixed well, and this composition was designated as B-1.

Next, B-1 and A-1, A-2 or A-3 100/1
The results of these adhesive properties are shown in Table 1. The adhesiveness was measured by measuring the shear adhesive force according to ASTM D-1002. The curing condition of the adhesive was 120 ° C./hour.

Example 2 In a four-necked flask equipped with a stirrer, a thermometer and a Gene Stark condenser, a hydroxyl group-capped dimethylsiloxane-methylvinylsiloxane copolymer at both ends (a molar ratio of dimethylsiloxane units to methylvinylsiloxane units of 3 /
1, average molecular weight 450) 100 parts, 3-glycidoxypropyltrimethoxysilane 42 parts and α, ω-dimethylsiloxanediol potassium salt (alkaline equivalent 1200 g / eq) 0.
2 parts were added and heated with stirring. The low boiling point substances (mainly methanol) were distilled off while reacting at a temperature of 130 ° C. After reacting for 2 hours, it was neutralized with acetic acid, and low-boiling substances were removed by distillation under reduced pressure at 130 ° C. and 5 mmHg. The obtained polysiloxane was analyzed by IR, FTNMR, and GPC and found to have the following average formula.

[RSiO _3/2 ] _0.09 (wherein R is 3-glycidoxypropyl group) This polysiloxane was designated as A-4.

Further, organopolysiloxanes A-5 and A-6 were produced in exactly the same manner except that another lot of dimethylsiloxane-methylvinylsiloxane copolymer and 3-glycidoxypropyltrimethoxysilane were used (the organopolysiloxane obtained was still used). The average formula of polysiloxane is A-
4 was exactly the same).

Similarly, instead of the above dimethylsiloxane-methylvinylsiloxane copolymer, dimethylsiloxane-methylhexenylsiloxane copolymer (molar ratio of dimethylsiloxane units and methylhexenylsiloxane units 3/1, average molecular weight 520) Organopolysiloxane prepared in exactly the same manner as A-2 except 110 parts was used.
And

Next, 100 parts of dimethylpolysiloxane having an average molecular weight of 5500 with both ends dimethylvinylsiloxy group blocked, and dry silica treated with hexamethyldisilazane (specific surface area)
200m ² / g) 20 parts, 0.15 parts of a 2% isopropyl alcohol solution of chloroplatinic acid, 3-methyl-1-butyn-3-ol
0.01 part and 5 parts of a copolymer of dimethylsiloxane methylhydrogensiloxane (the molar ratio of dimethylsiloxane and methylhydrogensiloxane is 5/5) was mixed well with 0.01 part and an average molecular weight of 1200 with both ends trimethylsiloxy group blocked. The composition was designated as B-2.

Next, B-2 was mixed with A-2 or A-3 at a weight ratio of 100 / 1.5, and the results of the adhesiveness thereof are shown in Table 2. The adhesiveness was measured as in Example 1. The curing condition of the adhesive was 130 ° C./30 minutes.

Example 3 2 parts of "A-1" prepared in Example 1, 2 parts of ethyl silicate, 1 part of tetrabutyl titanate and 10 parts of hexane.
An undercoat (primer) was prepared by uniformly mixing 0 parts.

After applying this to an iron plate, it was dried at room temperature for 1 hour, "B-1" produced in Example 1 was applied, and heat-cured at 100 ° C for 2 hours.

Further, B-1 was similarly applied to the iron plate without using the undercoating agent, and was cured by heating.

As a result of peeling off the adhesion part of these organopolysiloxane cured product and the iron plate with a knife, as a result of the test, those with the undercoating agent did not peel off, and those without the undercoating agent easily peeled off. It was

EFFECTS OF THE INVENTION Since the adhesion promoter of the present invention is mainly composed of an organopolysiloxane composed of a specific organopolysiloxane unit having an epoxy group, an alkoxy group and an alkenyl group, it has excellent reproducibility of adhesive properties. There is a feature that

Claims (1)

(57) [Claims] 1. A unit represented by the formula R ¹ SiO _3/2 , a unit represented by the formula R ¹ R ² aSiO _{(3-a) / 2} , and a unit represented by the formula R ² bR ³ cR ⁴ dSiO _(4- bc- _{d) / 2} and an adhesion promoter mainly composed of an organopolysiloxane composed of a unit represented by the formula R ³ eR ⁴ fSiO _(4- ef _{) / 2} (wherein R ¹ is an epoxy group). A monovalent organic group, R ² is an alkoxy group, R ³ is a monovalent hydrocarbon group excluding an alkenyl group, R ⁴ is an alkenyl group, a and b are 1 or 2, and c, d, e and f Is a number of 2 or less, e + f is a number of 1 or more, the ratio of R ^{1 to} all organic groups is 2 mol% or more, and
The ratio of R ² is 5 mol% or more, and the ratio of R ^{4 to} all organic groups is 2 mol% or more).