JPS6323226B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to compositions for producing silicone elastomers that have improved adhesion to substrates in the cured state, and also to compositions that promote such improved adhesion. BACKGROUND OF THE INVENTION Silicone elastomer forming compositions that can be cured to form elastomers at normal ambient temperatures are well known in the industry. Compositions of this type are available in two types. That is, one mold consists of a composition (one-component composition) that is supplied in one container and hardens when exposed to atmospheric moisture. The other type is a composition that is supplied in two containers (i.e., two parts) and which hardens when the contents of the two containers are mixed in a predetermined proportion. liquid type composition). usually,
One container of the latter type of composition contains a hydroxyl-terminated polydiorganosiloxane and one or more fillers, and the other container contains silicon-bonded alkoxy or alkoxyalkoxy groups per molecule. Contains an average of two or more silanes or siloxanes and a curing catalyst. Other additives such as additional fillers, plasticizers and pigments can be placed in either or both containers. Such two-container compositions (two-part compositions) are described, for example, in British Patent No. 841,825;
No. 844128, No. 867511 and No. 938399. Problems to be Solved by the Invention For certain applications of the two-component compositions described above, it is often desired to improve the adhesion of the cured elastomer to substrates, such as glass, aluminum or concrete. . It is known that improved adhesion can be achieved by incorporating into the composition silanes or siloxanes having amino-substituted organic groups in the molecule. One such adhesion promoter is aminopropyltriethoxysilane. Another known adhesion promoter for two-part compositions is glycidoxypropyltrimethoxysilane. Although both of these silanes provide good adhesion to a wide range of substrates, it has been found that the adhesive bond deteriorates rapidly in wet conditions. Means to Solve the Problem We surprisingly found that the wet adhesion of a two-component composition could be improved by incorporating both an amino-substituted silane and an epoxy group-containing silane into the composition. I found out that it can be achieved. Therefore, the present invention provides (A) a polydiorganosiloxane whose terminal end is a silanol group; (B) a group bonded to a silicon atom selected from an alkoxy group having 6 or less carbon atoms and an alkoxyalkoxy group in the molecule; A crosslinking agent for (A) which is a silicon compound having at least 3 atoms; (C) a metal salt or an organic metal salt of a carboxylic acid; (D) a general formula Silane represented by (in the formula, R is a hydrogen atom, 1 to 4
an alkyl group having carbon atoms, or carbon-
is an aliphatic hydrocarbon group containing at least one amino group and is bonded to the nitrogen atom via a nitrogen bond, R' is an alkylene group having 3 to 6 carbon atoms, and X is 1 to a monovalent hydrocarbon group having 6 carbon atoms, Y is an alkyl group or alkoxyalkyl group having up to 6 carbon atoms, and a has a value of 0 or 1), and (E) the general formula A silane represented by an organic group consisting of carbon, hydrogen and oxygen having a group represented by an alkyl group, B has a value of 0 or 1)
There is provided a composition comprising a product obtained by mixing. The present invention also includes mixing the above components (A) to (E) and then curing the resulting composition.
Also provided are methods of making elastomers. Function The organic substituent in polydiorganosiloxane (A) is a lower aliphatic hydrocarbon group such as a methyl group, an ethyl group, a propyl group or a vinyl group, a phenyl group or a fluorinated hydrocarbon group such as 3,3,3
-trifluoropropyl group.
Preferably at least 50% of the substituents are methyl groups and the remaining groups are selected from phenyl and vinyl groups. The most preferred polydiorganosiloxane is polydimethylsiloxane. The viscosity of the polydiorganosiloxane is not critical and is determined by a variety of factors, including the intended use of the final product. Generally 500 or more at 25℃
Polydiorganosiloxanes with viscosities in the range of 100,000 mPa can be used, but preferred polydiorganosiloxanes have viscosities in the range of 1,000 to
It has a viscosity in the range of 75000mPa. Polydiorganosiloxane (A) is a known substance.
They are widely used in the production of room temperature vulcanized silicone elastomers and have the general formula HO−SiR″ ₂ (OSiR″ ₂ ) _X OH, where R″ is an organic substituent, e.g. a methyl group,
Also, X is an integer, preferably about 300 to
with an average value of 1500). As the crosslinking agent (B), any silicone compound having at least three silicon-bonded alkoxy groups or alkoxyalkoxy groups in the molecule or a mixture thereof can be used. The silicone compound may be a silane or a siloxane. Examples of such silicone compounds are alkyl orthosilicates such as ethyl orthosilicate and propyl orthosilicate, alkyl polysilicates such as ethyl polysilicate and n-propyl polysilicate, monoorganotrialkoxysilanes such as methyltrimethoxysilane, ethyltrimethoxysilane, They are methyltri-n-propoxysilane, butyltriethoxysilane and phenyltrimethoxysilane.
Other silicone compounds that can be used include:
Included are Si( _OCH2CH2 - _OCH3 ) ₄ and methylpolysiloxanes containing alkoxy groups, such as methoxy or ethoxy groups, bonded to _the silicon. Generally preferred crosslinking agents (B) are silanes having 3 or 4 silicon-bonded alkoxy groups, or products of partial hydrolysis and condensation of such silanes. Silicone compounds (B) are generally polydiorganosiloxanes with silanol terminals.
It is used in a proportion of about 1 to about 15 parts by weight per 100 parts by weight of (A). Component (C) of the composition of the present invention is a curing catalyst,
Consists of metal or organic metal salts of carboxylic acids.
The metal can be, for example, zinc, cobalt or lead, but is preferably tin. An example of salt (C) is
They are zinc naphthenate, lead octoate, tin octoate (), dibutyltin dilaurate, dibutyltin dioctoate and dibutyltin diversatate. The curing catalyst (C) is generally used in a proportion of 0.1 to 10% based on the weight of (A). Compositions of (A), (B) and (C) are known in the organosilicon industry and are included in commercially available materials. Compositions of this type are known, for example, from British Patent No. 841825.
No. 844218 and No. 938399. Component (D) of the compositions of the present invention contains a silicon-bonded hydrocarbon group containing in the molecule a silicon-bonded hydrocarbon oxy group and at least one amino group (preferably up to 12 silicon-bonded hydrocarbon groups). carbon atom) and 1
Consists of one or more species of silane. In the general formula of silane (D), the substituent R is hydrogen, a lower alkyl group, or an aliphatic group containing at least one amino group. Therefore, R is, for example, H, a methyl group,
an ethyl group, a propyl group, a group -(CH ₂ .CH ₂ .NH) _Z H (wherein Z is an integer, preferably 1 or 2) or a group H ₂ NQ- (wherein Q is Divalent hydrocarbon groups, such as -CH.CH ₃ CH ₂ -, -(CH ₂ ) ₄ - or -(CH ₂ ) ₅
- can be). The substituent Y is, for example, a methyl group, an ethyl group or a methoxyethyl group. Suitable components as component (D) are compounds represented by the formulas H ₂ N(CH ₂ ) ₂ NHR′Si(OY) ₃ and H ₂ NR′Si(OY) ₃ (wherein R′ is 3 or an alkyl group having 4 carbon atoms, e.g. -(CH ₂ ) ₃
- or CH ₂ CH・CH ₃ CH ₂ -, and each Y
is a methyl group, an ethyl group or a methoxyethyl group). As component (E) of the composition, one or more silanes having silicon-bonded hydrocarbon oxy groups and silicon-bonded organic groups containing epoxy groups are used. . In the general formula of silane (E), substituent Z is any organic group containing an epoxy group and consisting of carbon, hydrogen and oxygen. Examples of such substituents are the general formula where Q' is a divalent group such as -CH ₂ CH ₂ -, -(CH ₂ ) ₃ -, -CH ₂ CH.CH ₃ CH ₂ -, phenylene, cyclohexylene,

-CH ₂ CH ₂ OCH ₂ CH ₂ - and -CH ₂ CH ₂ OCH(CH ₃ )CH ₂ -, and the group M is, for example, a methyl, ethyl or methoxyethyl group. Preferably Z is a group and M is a methyl or ethyl group. Improvements in wet cured elastomer adhesion to glass, aluminum and concrete are observed when the aminosilane (D):epoxysilane (E) molar ratio present in the composition is from about 0.1:1 to about 3:1. be done. However, optimal results appear to be obtained when the molar ratio of (D):(E) is in the range of 0.4:1 to 0.7:1. The degree to which the adhesion of the cured elastomer is improved in the wet state depends in part on the proportions of (D) and (E) that are mixed into the cured composition. Best results are obtained when the total weight of (D) and (E) used is about 1.5% to about 4.5% based on the weight of polydiorganosiloxane (A). More than 4.5% by weight may be used, but such high additions are not expected to result in further improvements in adhesion. The composition of the present invention is prepared by simply mixing components (A) to (E) in the desired proportions. However, (A),
Compositions of the type consisting of (B) and (C) are usually supplied as two-part products, where the catalyst (C) is the polydiorganosiloxane (A) and the catalyst (C) is the polydiorganosiloxane (A). contained in a separate container. Crosslinker (B) and (A)
It may be mixed with (C), or it may be mixed with both. Upon use, mixing the contents of the container will begin curing. Thus, silane (E) may be contained in the container as a mixture with polydiorganosiloxane (A), and silane (D) may be present as a mixture with catalyst. Aminosilane (D) is used when storage stability of the composition is required.
It is preferable that it should not be mixed with (A). but,
It has been found that the best results are obtained when (D) and (E) are combined and then mixed with the remaining components of the elastomer-forming composition. Therefore, components (D) and (E) are preferably mixed together and placed in a container separate from the two containers containing (A), (B) and (C). Preferably, however, (D) and (E) are contained in a container as a mixture with catalyst (C) to provide the elastomer-forming composition as a two-part product. (D) and (E)
It is not clear why adhesion is improved by combining these. However, it is believed that the silanes react upon mixing and that it is the reaction products that contribute to the improved wet adhesion. If desired, the mixture can be heated (eg, to 25-70°C) to increase the rate or extent of the reaction. However, such a heating step is not a necessary requirement. In addition to components (A) through (E) as defined above, the compositions of the present invention can include any other components commonly present in silicone elastomer forming compositions. In particular, various fillers such as silica aerogel, diatomaceous earth, powdered quartz, zinc oxide, titanium dioxide, calcium carbonate, iron oxide and carbon black can also be mixed. Other ingredients which may likewise be present are pigments, heat stabilizers and polydiorganosiloxanes such as polydimethylsiloxanes having triorganosilyl units, such as trimethylsilyl units, at one or both ends of the molecule. When cured, the compositions of the invention exhibit good adhesion, especially in wet conditions, to substrates such as glass, aluminum, concrete and plastics, such as polycarbonate, polyester and ABS. The compositions of the invention are therefore particularly suitable for use in applications where such adhesion is required, such as for use as a sealant for glazed equipment and concrete structures. In addition to improved adhesion, the cured elastomer was observed to absorb less water than elastomers using known aminosiloxane additives. EXAMPLES The invention is illustrated by the following examples (hereinafter simply referred to as examples) expressed in weight percent. The percentages in the text are percentages by weight. Example 1 A two-part elastomer-forming composition was prepared as follows: Part A was prepared by mixing 50% silanol-terminated polydimethylsiloxane (12500 mPa at 25°C) and 50% calcium carbonate; Part B was prepared by mixing 50% calcium carbonate; It was obtained by mixing 25.8% Si (OCH ₂ CH ₂ CH ₃ ) ₄ , 7.5% carbon black, 0.55% dibutyltin dilaurate, and 66.15% polydimethylsiloxane (12500 mPa at 25°C) terminated with trimethylsilyl. Part B contains NH ₂ (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ 5.0%. 8.3% was added to give an aminosilane:epoxysilane molar ratio of 0.65:1. This composition was prepared at room temperature for 24 hours.
I left it for a while. Part A and Part B were thoroughly mixed in a weight ratio of 1 part B to 10 parts A, and the resulting composition was used to create a "H sample" and SNJF (France) Test Method 85-
504 test was conducted. "Sample H" was constructed using parallel plates (5 cm x 5 cm) of glass, rolled aluminum and concrete, respectively, with rectangular beads of cured elastomer forming rungs between the plates. The concrete "H sample" was placed in water at 50°C for 3 days, the plate was pulled and released at a speed of 50 mm per minute, and the tensile force at which the sample fractured was recorded. The fractured samples were also inspected to confirm the fracture mode. If the elastomer breaks internally, it is recorded as adhesive failure. Adhesive failure occurs when the elastomer separates from the substrate without tearing. Adhesive failure indicates that the adhesive bond between the elastomer and the substrate is stronger than the elastomer itself. Boundary failure is a condition where separation is not due to snapping and adhesive failure, but occurs near the elastomer/substrate interface. If only adhesive failure is specified in the data, the remaining % of failures are adhesive layer failures. The results obtained for the concrete samples were as follows: Table 1a Days of immersion Force at failure (Kg)
Failure mode 3 46 20% adhesive failure Glass and aluminum samples were tested at 50°C and 90°C.
The test results when the sample was immersed for the period shown below and separated as described above were as follows.

EXAMPLE 2 In this example, a sealant composition and catalyst/adhesion promoter were prepared as in Example 1, but only with γ-aminopropyltriethoxysilane and γ-aminopropyltriethoxysilane.
The difference is that the mixture with glycidoxypropyltrimethoxysilane was combined in a ratio of 0.85:1. Part B of this mixture contains 5.9% aminosilane,
A sufficient amount of epoxy silane was added to give a ratio of 7.4%, and "Sample H" was prepared using a glass substrate. The performance of this adhesion promoter in the sealant on the Karasu "H sample" is shown in Table 2. Table 2 90℃ water test time Force at failure (Kg) Failure mode 0 64 100% adhesion 75 25 30% adhesion Compared with the results in Table 1b, the results in Table 2 are as follows:
This shows that the adhesion promoter of Example 2 is less effective in the elastomer-forming compositions tested. Example 3 In this example, a sealant composition and catalyst/adhesion promoter were prepared as in Example 1, but sufficient silane was added to Part B to give a proportion of 2.9% epoxysilane and 1.7% aminosilane. It differs from Example 1 in that it was mixed in The performance of this adhesion promoter in the sealant on the glass "H sample" is shown in Table 3. Table 3 90℃ water test time force at failure (Kg) failure mode 0 50 100% adhesion 75 19 30% adhesion 100 12 10% adhesion Example 4 In this example, the sealant and adhesion promoter are used in Example 1 However, based on part B, epoxysilane was 21.4% and aminosilane was 13%.
The difference from Example 1 is that sufficient amount of silane mixture was added to give a proportion of %. The results obtained from the tests on the glass "H sample" are shown in Table 4.

[Table] Example 5 In this example, the sealant and adhesion promoter were prepared as in Example 1, except that N-(trimethoxysilylpropyl)ethylenediamine was used in place of γ-aminopropyltrimethoxysilane. This is different from Example 1. The molar ratio of amino/epoxy functional silane is 0.45/1, and the adhesion promoter is present in an amount sufficient to provide a proportion of 9.4% epoxysilane and 4.2% aminosilane (based on the weight of Part B). I added it to part B. The sealant was tested on glass and rolled aluminum as described in Example 1. The results are shown in Table 5.

[Table] Comparing the results shown in Table 5 with the results shown in Table 1b, the adhesion promoter of this example shows that the adhesion of the sealant is comparable to that obtained with the silane mixture used in Example 1. It can be seen that it is applied to the base materials of glass and aluminum. Example 6 In this example, the sealant and adhesion promoter were prepared as in Example 5, only the ratio of diamine:epoxy functional silane was changed to 0.25:1 and a sufficient amount of the silane mixture was added to Part B. This differs from Example 5 in that the epoxysilane was 11% and the aminosilane was 2.7%. The resulting sealant was tested for adhesion to glass and rolled aluminum according to the procedure described in Example 1. The results are shown in Table 6.

[Table] Example 7 (Comparative example) In this comparative example, the sealant and adhesion promoter were used in Example 1.
Example 1 was prepared as in Example 1 except that the epoxysilane was omitted and only aminosilane was used as the adhesion promoter. Aminosilane was added to part B in a proportion of 12.8% by weight, based on the weight of part B. Concrete with the generated sealant,
An "H sample" using glass and rolled aluminum substrates was constructed and tested for adhesion as in Example 1. The results are shown in Table 7.

TABLE A comparison of the results shown in Table 7 with those shown in Tables 1a and 1b clearly shows the improvement in adhesion exhibited by the adhesion promoter of the invention.
Comparing the results in Table 7 with the results shown in Tables 2 and 3 shows that the performance of the adhesion promoter of the invention in Example 7
The performance of the adhesion promoter of the present invention is superior to that of the prior art adhesion promoter (Comparative Example), even when the adhesion promoter of the present invention is used in an unfavorable ratio of aminosilane to epoxysilane (Example 2). It can be seen that this also appears when used at a non-preferred concentration (Example 3). Example 8 (Comparative Example) In this comparative example, the procedure of Example 1 was repeated, except that the aminosilane was omitted and only epoxysilane was used as the adhesion promoter.
Epoxysilane was added to Part B in a proportion of 13.7% by weight based on the weight of Part B. The above-mentioned 50℃ and 90℃ for the "H sample" made of glass and aluminum substrates using the generated sealant.
A water test was conducted. The results are shown in Table 8.

[Table] Comparing the results shown in Table 8 with the results shown in Table 1, the performance of the adhesion promoter of the present invention is greater than that obtained using only the epoxy functional silane as the adhesion promoter. It shows that there is a dramatic improvement. Example 9 (Comparative Example) In this comparative example, the procedure of Example 1 was repeated, except that the molar ratio of aminosilane/epoxysilane was 2.5.
This is different from Example 1 in this respect. Aminosilane and epoxysilane were added in proportions of 9.2% and 3.9%, respectively, based on the weight of Part B. The sealant prepared according to this example was tested on glass and rolled aluminum substrates according to the procedure of Example 1. The results are shown in Table 9.

[Table] Comparing the results shown in Table 9 with the results shown in Table 7, it can be seen that when the components are combined such that the molar ratio of amino-functional silane/epoxy-functional silane is 2.5, the silane of Example 1 It can be seen that the ivy adhesion promoter does not show any improvement in glass adhesion, but some improvement in aluminum adhesion is evident. Example 10 In this example, a sealant and adhesion promoter were prepared according to Example 1, but with an aminosilane/epoxysilane ratio of 0.4/1. Aminosilane and epoxysilane are each 3.7% based on part B.
Added at a rate of 9.8%. The resulting sealant was used to create an "H sample" made of glass and rolled aluminum. The test described in Example 1 was carried out on the "H Sample" and the results are shown in Table 10.

[Table] Comparing the results shown in Table 10 with the results shown in Tables 7 and 8, it can be seen that with an aminosilane/epoxysilane ratio of 0.4, silane alone was added at the same concentration and rolled with glass. It shows that the sealant adheres better to glass and rolled aluminum substrates than either to aluminum. Example 11 (Comparative Example) In this comparative example, a two-component silicone sealant composition was prepared with 50% polydimethylsiloxane having a silanol terminal and a viscosity of 50000 mPa as part A and 5μ
20% ethyl orthosilicate as Part B, 13% aminosilane adhesion promoter used in Example 7, 0.25% dibutyltin dilaurate, and the balance 100%.
% with a viscosity of 12500 mPa at 25° C. and a trimethylsilyl-terminated polydimethylsiloxane. When parts A and B were mixed in a ratio of 10 parts A to 1 part B, the resulting composition cured to form an "H sample" on the glass substrate as in Example 1. The thus prepared "H sample" was subjected to a 90°C water test, and the results are shown in Table 11. Table 11 90°C water test Time force at failure (Kg) Failure mode 7 2 Example of 100% adhesive layer 12 In this example, a silicone sealant was manufactured as in Example 11, except that part B contained an adhesion promoter. A mixture of aminosilane and epoxysilane as described in Example 1 is combined in an aminosilane/epoxysilane molar ratio of 0.65/1,
Epoxy silane is 8.3% based on the weight of part B.
This differs from Example 11 in that aminosilane was added to Part B at a rate of 5%. Part A and Part B were mixed to form a curable silicone sealant, which was then cured to form "Sample H" using a glass base. Hardened "H sample"
A 90°C water test was carried out as in Example 11, and the 12th
The results shown in the table were obtained. Table 12 90°C Water Test Time Force at Failure (Kg) Failure Mode 7 14 35% Adhesion Example 13 A two-part elastomer-forming composition was prepared as described in Example 1. To Part A was added 0.83% (based on the weight of Part A) of the epoxysilane described in Example 1, and to Part B was added 5.0% of the aminosilane of Example 1.
% (based on the weight of Part B) was added. Parts A and B were then thoroughly mixed in a weight ratio of 10 parts of A to 1 part of B. A glass substrate "H sample" was prepared using this composition, immersed in 90°C water, and tested as described in Example 1.
The results were as follows.

【table】

Claims (1)

[Claims] 1. (A) a polydiorganosiloxane whose terminal is a silanol; (B) a silicon-bonded group selected from an alkoxy group and an alkoxyalkoxy group having 6 or less carbon atoms in the molecule; A cross-linking agent for (A) which is a silicon compound having at least three, (C) a metal salt or organometallic salt of a carboxylic acid, and (D) a general formula A silane represented by [Formula R is a hydrogen atom, an alkyl group having from 1 to 4 carbon atoms, or a silane bonded to a nitrogen atom via a carbon-nitrogen bond and containing at least one aruno group] represents an aliphatic hydrocarbon group containing R' represents an alkylene group having from 3 to 6 carbon atoms;
represents a monovalent hydrocarbon group having from 1 to 6 carbon atoms, Y represents an alkyl group or an alkoxyalkyl group having up to 6 carbon atoms, and has a value of a or 0 or 1 ] in which the composition contains a product obtained by mixing (E) with the general formula A silane represented by represents an organic group consisting of carbon, hydrogen and oxygen having a group of
an alkyl group or alkoxyalkyl group having up to 1 mol of carbon atoms, and b has a value of 0 or 1), and furthermore, (D) and (E) are added per mole of (E) (D ) A composition characterized in that it is used in a ratio of 0.1 to 3 moles. 2. The composition according to claim 1, wherein the molar ratio of aminosilane (D):epoxysilane (E) is in the range of 0.4:1 to 0.7:1. 3. A composition according to claim 1 or 2, wherein (D) and (E) are mixed together and then mixed with the remaining components of the composition.