DE1961555A1 - Silicone resin hardening at room temperature - Google Patents

Description

Th. Goldschmidt A.-G. , - food

Silicone resin that hardens at room temperature

The invention relates to an under the action of water, especially humidity, silicone resin that hardens at room temperature.

Silicone resins usually consist of mono-, di ~, tri and tetrafunctional silicon units. Your condensation to higher molecular weight compounds and hardening is brought about by the fact that silanol groups with cleavage of (J Condense water together. This requires the use of higher temperatures. Silicone resins are therefore usually branded.

One can have the condensation of the silanol groups Silicone resins also have the effect of using catalysts clogs. Such catalysts are organometallic compounds, such as dibutyltin dilaurate, the addition of

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Curing catalysts must be used immediately prior to processing happen because the mixtures have only a limited pot life and within a short time even at room temperature condense out ("Chemistry and Technology of Silicones" by Walter Noil, Verlag Chemie GmbH, 1968, page 357 ff.). Man can counteract premature hardening by using the resins in relatively large quantities of solvents dissolves and / or adds very small amounts of catalyst. However, both procedural measures are application-related disadvantageous. In the first case, the amount of solvent must escape from the applied resin solvent layer, whereby films of very small thicknesses are formed, which are also often porous. Because of the small amount of catalyst Then the curing of the films takes place proportionally slow.

The present invention is based on the object Room temperature hardening and despite the addition of a catalyst below Exclusion of water, especially air humidity, synthetic resins in the form of one-component systems which can be stored for any length of time to obtain, which remain stable in storage even in the absence of solvents. .

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Surprisingly, this task can be achieved by a silicone resin be resolved which end groups of the structure

R ¹

¹ 2
-Si-OR

• 2

wherein R is an alkyl or an aryl radical or the meaning

2 2

of the group OR and OR has an alkoxy radical with 1 to 4 carbon

Γ 13 '3

or the radical ItX ^ H ^ j OR, where R is a Is alkyl, preferably the methyl radical, and n. Is a value of 1 or 2 has, is free of silanol groups and contains organometallic curing catalysts known per se in amounts of 0.1 to 5% by weight.

The silicone resins according to the invention are cured presumably in such a way that in the presence of atmospheric moisture and under the action of the organometallic catalysis

2 '

gates hydrolyze the OR groups and then condense.

As mentioned above, the. Remainder R the meaning of a Have alkyl radicals. The lower alkyl radicals are preferred such as the methyl or ethyl radical. However, higher alkyl radicals can also be used. In one example, a

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Described silicone resin, in which the radical R has the meaning of an octadecyl radical. However, these residues have an effect already plasticizing the resins. This can be for special Applications are desirable. The rest of R. can also do the Have the meaning of an aryl radical, the phenyl radical being preferred. ·. .

2 - '
The OR radical can have the meaning of a lower alkoxy radical which can have up to four carbon atoms. Examples include methoxy, ethoxy, n-propoxy,

i-propoxy, n-butoxy and i-butoxy radicals. The OR radical can also have the meaning of an alkylene glycol monoether radical of the general formula | o ^c 2 ^H 4Jn ^OR . In this formula, η has a value of 1 or 2. R is an alkyl radical, preferably the methyl radical.

The content of the end groups of the formula in the silicone resin

R ¹

¹ 2

-Si-OR

¹ 2

is variable within wide limits. From the task it is obvious to the person skilled in the art that a minimum required for crosslinking with curing

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number of such groups must be present. Particularly preferred are those silicone resins which these groups in a molar ratio of 1: 3 to 1:20, based on the remaining Si atoms of the resin contain.

As organometallic curing catalysts, in principle all from the state of the art ("Chemistry and Technology of Silicones" by Walter Noil, Verlag Chemie GmbH, 1968, p 340) known compounds are taken, however, the dialkyldiacytin compounds, preferably dibutyl tin dilaurate, are preferred. These curing catalysts are added to the silicone resins at any point in time after their preparation in amounts of 0.1 to 5% by weight, preferably in amounts of 0.5 to 3% by weight.

With the exclusion of atmospheric moisture, the catalysts are It contains resins according to the invention with virtually unlimited storage stability. A particular advantage here is that the. Resins can be stored and used without solvents, provided they have a viscosity by themselves, which allows their processing. However, the resins are for direct processing to high viscosity is the use of solutions of synthetic resins for other reasons The silicone resins can advantageously be used in the solvents customary for the compounds, preferably aromatic

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- D ""

Solvents, esters and ketones are dissolved. Examples of such solvents are benzene, toluene, xylene and their mixtures or commercially available aromatic distillates or solvents based on esters and ketones, such as ethyl acetate, butyl acetate, ethyl glycol acetate, methyl ethyl ketone.

Silicone resins according to the invention which harden at room temperature can be built up from various Si units. Examples of such units are CH ₃ SiCUy ₂ '(CH ₃ ) "SiO; C ₆ H ₅ Si0 ₃ y ₂ ; (G ₆ H ₅ J ₂ SiO; (CH ₃ J ₃ SiO; SiO _4/2 ; (CH ₃ ) HSiO.

The production of the silicone resins, which in the context of this er-. Finding is not claimed, for example, can be carried out according to the following reaction scheme:

ESiOH + Cl-SiR ¹ (OR ² ) ₂ > 5

This reaction scheme is based on the principle, corresponding To implement siloxanols with chlorosilanes which have at least two carbyloxy groups. The one at the Hydrogen halide released in the reaction can be captured by acid acceptors such as ammonia. The reaction is expediently carried out at a higher temperature.

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Another manufacturing process is based on implementation corresponding siloxanols with tri- or tetraalkoxysilanes;

R ¹ "■ R ¹

= Si-OH + .R ² O-Si-OR ² ^ SiO-Si-OR ² I 2 I.

The silicone resins according to the invention, which harden at room temperature under the action of water, in particular atmospheric moisture, can be used wherever silicone resins have hitherto been used. However, they are particularly advantageous to use where higher temperatures cannot be used. This is the case, for example, when the substrate to be coated with the silicone resin is temperature-sensitive or, due to its dimensions, is not readily suitable for the application of baking techniques. For example, the silicone resins according to the invention are suitable for coating Luminesenζröhren or screens , it being possible for the resins to be pigmented with phosphors. Another use is the coating of technical papers, for example photocopy papers, which contain heat-sensitive pigments.

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961 555

The subject matter of the present invention becomes in the following Examples are explained in more detail. The ones in the examples parts given are parts by weight. ■

example 1

225 g of a 25% solution of a cohydrolyzate of methyltrichlorosilane and dimethyldichlorosilane with an OH group content of 4.2 wt. % and a molar ratio of CHo: Si = 1.2: 1 in toluene. With stirring and simultaneous introduction of gaseous NH ₃ , 19 g of CgH ₅ Si (OC ₂ H ₅ ) ₂ Cl are added dropwise over 15 minutes at .50 ° C. The molar ratio of OH groups of the aforementioned cohydrolyzate and Cl in the silane is 1: 1. With continued stirring, NH _{3 is passed} in at 50 ° C. for a further hour. The reaction mixture is then slowly heated to 10Ö ° C and. stirred at this temperature for one hour. The mixture obtained is freed from the ammonium chloride formed by filtration. The solution obtained is mixed with 1% dibutyltin dilaurate, based on the. Solids content. Under "Axis closure of air

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moisture, no condensation occurs while that occurs A product painted on a glass plate and exposed to the influence of atmospheric moisture after several hours forms a solid resin film. Part of the solution is through Completely freed from the solvent by distillation. The remaining ammonium chloride which precipitates out is filtered off. That liquid, 100% resin containing dibutyltin dilaurate remains liquid and condenses in the absence of atmospheric moisture but with the ingress of humidity to a solid resin.

Example 2

According to the method given in Example 1, 324 g of a 25% strength toluene solution of a cohydrolyzate of methyltrichlorosilane and dimethyldichlorosilane with an OH group content of 2.6% by weight and a molar ratio of CH ₃ ί Si = 1.2: 1 reacted with 19.5 g of CH ₃ (OC ₂ H ₅ ) ₂ SiCl, corresponding to an OH: Cl ratio of 1: 1. Both the filtered solution and the liquid resin freed from the solvent remain excluded after catalysis with 1% dibutyltin dilaurate from humidity liquid. The silicone resin hardens when exposed to humidity.

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Example 3

According to the method given in Example 1, 324 g of a 25% strength toluene solution of a .Cohydrolyzate of methyltrichlorosilane and diraethyldichlorosilane with an OH group content of 2.6% by weight and a molar ratio of CH ₃ : Si "= 1, 2: 1 reacted with 39 g of CH ₃ Si (OC ₂ H ₅ ) ₂ C1 corresponding to an OH: Cl ratio of 1: 2 (product 1).

Using the same method, 153 g of a 25% strength toluene solution of a cohydrolyzate of methyltrichlorosilane and dimethyldichlorosilane with an OH group content of 2.6% by weight and a molar ratio of CH ₃ : Si = 1.2: i with 28 g of CgH ₅ Si (OC ₂ H ₅ ) ₂ C1 converted according to an OH: Cl ratio of 1: 2 (product 2).

Products 1 and 2 are mixed with 1% dibutyltin dilaurate and remain in the presence of solvents Liquid with exclusion of atmospheric moisture. They condense solid resins when exposed to moisture.

Applied to deep-drawn sheets by humidity Resin films condensed out show those in the following table specified values,>. .

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product Erichsen depression Cross-cut Pencil hardness ι ·
2 8.0 mm
9.9 mm Gt 1
Gt 0 '5 H
; , 2 H. .

After a temperature load of 200 ° C. for 24 hours Product 1 and 2 give the cross-cut values Gt 0 ·.

Example 4. .

490.5 g of a 25% strength toluene solution of a cohydrolyzate of 135 parts of methyltrichlorosilane, 17.5 parts of dimethyldichlorosilane, 17.5 parts of trimethylchlorosirane, 23 parts of methyldichlorosilane and 17.5 parts of tetrachlorosilane with an OH group content of 1.15% are reacted analogously to Example 1 with 20 g of CgH ₅ Si (OG ₂ H ₅ ) "Cl corresponding to an OH: Cl ratio of 1: 1. Both the filtered solution and the liquid resin freed from the solvent remain liquid after catalysis with 1% dibutyltin dilaurate in the absence of atmospheric moisture. The silicone resins condense, painted on glass plates / when exposed to atmospheric moisture, they form solid resin films.

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Example 5

240 g of a 25% strength solution of a cohydrolyzate of methyltrichlorosilane and dimethyldichlorosilane with an OH group content of 2.6% by weight and a molar ratio of CH ₃ : Si = 1.2 ': 1 in toluene are used as in Example 1 25 g of C ₁₈ H ₃₇ Si (OC ₂ H ₅ ) ₂ C1 converted into an OH: Cl ratio of 1: 1. The solution of the resulting resin is liquid, the solvent-free product is waxy. Both the solution and the waxy resin from which the solvent has been removed do not change even after catalysis with 1% dibutyltin dilaurate when atmospheric moisture is excluded. However, when painted on glass plates, they condense on exposure to atmospheric moisture to form solid resin films with a greasy feel.

Example 6

200 g of a 25% strength toluene solution of a cohydrolyzate of methyltrichlorosilane and dimethyldichlorosilane with an OH group content of 2.6% by weight and a molar ratio of CH ₃ : Si = 1.2: 1 react with 63.7 g of tetraethoxysilane and 1.1 g of titanium butoxide catalyst under reflux for 4 hours.

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The solvent, the excess tetraethoxysilane and the alcohol formed are then distilled off. 6.8 g of ethanol were formed (theoretically 7.04 g of ethanol), The liquid resin freed from the solvent remains under exclusion even after catalysis with 1% dibutyltin dilaurate " from humidity liquid. It condenses, however, on Painted glass plates, solid resin films in contact with atmospheric moisture.

Example 7

200 g of a 25% toluene resin solution of a cohydrolyzate of methyltrichlorosilane. and dimethyldichlorosilane with an OH group content of 4.2% by weight and a molar ratio of CHg ί Si = 1.2: 1 are analogous to Bei- | game 1 with 117.8 g of CH ₃ Si (OC ₂ H ₄ OGH ₃ ) ₂ C1 according to an 'OH: Cl ratio of 1: 2. Both the filtered solution and the liquid resin freed from the solvent remain liquid even after catalysis with 1% dibutyltin dilaurate in the absence of atmospheric moisture. However, when painted on glass plates, they condense when exposed to humidity to form solid resin films.

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Claims (4)

Claims 1. Under the action of water, especially humidity, silicone resin hardening at room temperature, characterized in that the silicone resin end groups ^{w of} the structure R ¹ ·.,. ■■ '2
-Si-OR * ¹ 2 where R is an alkyl radical, preferably a methyl radical, or an aryl radical, preferably a phenyl radical, or 2 2 has the meaning of the group OR and OR is an alkoxy radical with 1 to 4 carbon atoms or the remainder OC ₀ H. LOR 3 ■ * is, where R is an alkyl, preferably the methyl radical, and η has a value of 1 or 2, free of silanol groups and organometallic curing catalysts known per se in amounts of 0.1 to Contains 5% by weight. . 2. silicone resin, according to. Claim 1, characterized in that the molar ratio of the group _R l ¹ 2 f 2 ' ² 109825/2040 to the remaining Si atoms of the silicone resin 1: 3 up to 1:20. 3. Silicone resin according to claim 1 or 2, characterized in that that dialkyldiacyltin compounds are used as a curing catalyst, preferably dibutyltin dilaurate, in quantities from 0.1 to 5, preferably 0.5 to 3% by weight. 4. silicone resin according to one or more of the preceding claims, characterized in that it is in a solvent, preferably an aromatic solvent, in particular benzene, toluene or xylene or Mixtures thereof, is dissolved. · 109825/2040