DE2449494C3 - Use of organosilicon compounds as release agents - Google Patents

Description

wherein

a = Oor 1,

b has a value from 1 to .500, where if a = 0 then '5

must be ös3,
the group R ^{1 is} a hydrogen. Alkyl- or trimethylsilylresl: is,

the group R ^{2 is} either an alkyl radical with 8 to 32 carbon atoms or the radical - (CH ₂ ) IoCOOR 'or the radical - R ⁴ OCOCi ₂ -Z ₂ H ₂ S - ** in which R ^{4 is} a divalent radical, or the radical -R ⁴ OC ₈ -22H, 7_45 means, but up to 80 mol% of the aforementioned radicals can be replaced by the methyl radical, but at least one radical R ² per molecule is other than a methyl radical,

the group R ^{3 can be} a methyl radical or an alkoxy radical with 1 to 4 carbon atoms,

as an internal release agent during the hardening of amino or phenoplast resins while shaping.

The still soluble condensation products of phenol or urea, thiourea and / or melamine with formaldehyde are used on a large scale to impregnate and coat carrier webs for Surface treatment of wood-based panels or as a binder for molding compounds or for production used by sand molds or by grinding wheels. The enumeration of these areas of application is not in conclusion, but only to be understood as an example.

If the phenoplast or aminoplast resin precondensates are used to impregnate and coat Carrier sheets for the surface finishing of wood-based panels are these resin-coated carrier sheets pressed under curing conditions by means of a pressing tool on the surfaces of the wood-based panels. These tend to be phenolic or Aminoplast resins for gluing with the press plates. Similar bonds are used when deforming Observe molding compounds under curing conditions. The same applies to the manufacture of these Resin-bound forms, e.g. B. for the croning or hot-box process or in the production of Grinding wheels.

For all of these purposes it is known to be internal, that is to say the synthetic resin or its solution to use added release agents. As a separating agent against those that convey the surface structure Press plates for the surface treatment of wood-based panels are already used with paraffin or Wax emulsions, esters or partial esters of fatty acids with polyhydric alcohols or metal soaps are used. The use of ethylene glycol or propylene glycol has proven to be particularly useful. fatty acid esters highlighted (DE-OS 22 50 991).

When using the aforementioned resins for the production of molding compounds, one has in particular Metal soaps used. The same goes for the manufacture of sand molds that are cured by these resins and should be solidified i: n. For these purposes one has silicone oils have also been used in dissolved or emulsified form, but without satisfactory results Results to come.

An internal release agent is required to be used in small quantities is effective and easy to distribute in the medium, and no surface defects, such as e.g. B. gloss nails, caused. In particular when curing the resins at higher temperatures, e.g. B. from Molding compounds, it is important that the

jo release agent does not discolour at these temperatures.

The invention now relates to the use of special organosilicon compounds as internal release agents for the aforementioned purpose, these organosilicon compounds meeting the above requirements meet particularly well.

The invention is therefore characterized by the use of compounds of the general formula I.

Si —ΟΙ R ²

where a is -0 or 1,

has fine value from 1 to 500, where, if a = 0, fc must be £ 3,
the group R ^{1 is} a hydrogen, alkyl or trimethylsilyl radical,

the group R ^{2 is} either an alkyl radical with 8 to 32 carbon atoms or the radical - (CH ₂ ) IoCOOR ¹ or the radical - R ⁴ OCOCi ₂ -22H ₂₅ -4h, in which R ^{4 is} a divalent radical, or the radical - ROC ₈ - 22H17 .. 45

means, however, up to 80 mol% of the aforementioned radicals can be replaced by the methyl radical, but at least one radical R ^{2 per molecule}

is other than a methyl radical, the group R 'is a methyl radical or an alkoxy radical

with 1 to 4 carbon atoms,; ils internal release agent during the hardening of aminoiis or phenolic resins under molding.

Within the abovementioned compounds there are preferred ranges ^{for the radicals R 1} , R ² and R ^1. The radical R ¹ is when it has the meaning of an alkyl radical.

preferably a methyl or ethyl radical. However, this does not rule out that the products in which R ^{1 is} a higher alkyl radical are effective.

The radical R ² can be selected from various groups. Up to 80 mol%, preferably up to 50 mol%, can be CH2 groups. The remaining mol% are formed by residues as listed in the claim. If R ^{2 is} an alkyl radical, those alkyl radicals are preferred which have 14 to 22 carbon atoms. The radicals are also preferred for R ²

(CH ₂ J ₁₀ -C-OCH ₃
O

(CH ₂ J ₃ -OCC ₁₇ H ₃₅
O

Particularly suitable compounds are those which correspond to the formula I and where

R '= (CHj) iSi-

R ² = alkyl with 14 to 22 carbon atoms or

- (CH ₂ J ₁ OC-OCK ₃
O

- (CH ₂ I ₃ -OCC ₁₇ H ₃₅
O

R '= CHj

a = 1 and

b = 10 to 50.

The radical R ⁴ is a divalent radical, preferably an alkylene radical, in particular a radical of the formula (CH ₂ ) Ci where c is 2 or 3.

The R ³ radical is a methyl radical, but it can also be an alkoxy radical. The alkoxy radical generally has 1 to 4 carbon atoms. However, the methoxy or ethoxy radical is preferred.

The preparation of the compounds is familiar to the person skilled in the art. The connections can e.g. B. be prepared by starting from starting compounds in which the radical R ² (if it is not a methyl radical) is a hydrogen radical, these compounds being reacted with compounds which have a corresponding olefinically unsaturated group. Such reactions are shown in DE-AS Il 15,929.

The organosilicon compounds can, if their viscosity permits, be added in pure form to the phenolic or aminoplastic resins. ^{ösup 17} preferred The use concentration of these compounds is 0.05 to 0.5% by weight, based on the weight of the solid resin.

The superiority of the release agents according to the invention over those in DE-OS 22 50 991 as special ethylene glycol or propylene glycol fatty acid esters described as useful as well as other release agents used in practice based on waxes or those based on esters of fatty acids

ίο Glycerin is shown in the following example

example

To test the release effect, 100 parts by weight of a paper suitable for impregnation were used 50% aqueous melamine resin solution with 1 part by weight of a 35% emulsion of the test Release agent added. All emulsions of the release agents according to the invention were made according to the same Recipe using 10% by weight (based on the active ingredient to be emulsified) of an emulsifier, consisting of a mixture of alkoxylated fatty alcohols with an HLB value of 12.

With these release agent-containing melamine resin solutions, webs of white paper with a weight of 20 g / m ² were prepared by double impregnation in such a way that a dry application of 150 ± ^{10 g / m 2 was} achieved. The pre-condensation of the applied resin was carried out by heating at U5 ° C for 3 minutes.

The melamine resin films obtained in this way were pressed onto 8 mm chipboard at a press plate temperature of 145 ° C. and a pressure of 20 kgf / cm ² . The pressing time was determined which is necessary to allow the pressed part to fall off the press plate under the effect of its own weight after the press had been opened. This time is referred to as the "cut-off value" in the following tables. The release value for release agent-free melamine resin is 180, measured under the conditions mentioned.

The press plate used consisted of a hard chrome-plated brass plate and was in front of each Pressing process carefully freed from any adhering release agent residues from previous pressings.

The resistance of the release agents at higher temperatures was determined as follows:

5.0 g of the release agent to be tested were placed in a Petri dish (diameter 6 cm) in a drying cabinet Heated to 280 ° C for 20 minutes. It was then observed whether and how strong color changes were occurred. The results are compiled in the "yellowing test" column of the tables below.

Table 1
Comparative product

Release agent on the
Base of

Glycoclistearate
Fatty acid ester-l'aratTin mixture
Metal soap)!

the test result

Separating oiling

w crt test

70 brown

¹ K) brown

4? Brown

mi, inwnr -. 'irwl

Table 2

Release agents according to the invention

Composition of R ³ R ³ crfindun «appropriate release agent a H / ι 50 Test result (iiibungstesl (best! R ¹ R ¹ Separating CH ₁ CH ₁ 1 498 50 value pale yellow unchanged 1 (CHJ ₁ Si CH, - (CHj) ₁ OCOCpH ,, 1 500 50 40 unchanged 2 (CHj) jSi CH ₁ 8OMoI-VoCH ₁ 50 35 unchanged CH ₁ CH, 20 mol% - (CHjJjOCOCpH ,, 1 50 4th pale yellow pale yellow 3 (CH ₁ JjSi CH ₁ CH ₁ - (CHjJjOCOCpH ,, 1 50 1 35 pale yellow pale yellow 4th (CH ₁ J ₁ Si C ₂ H ₅ O CH ₁ - (CHj) JOCOCj ₁ H ₄₁ 1 1 1 30th unchanged unchanged 5 CjH, CH ₁ CH ₁ - (CHj) ₁ OCOCpH ,, 1 50 50 25th unchanged unchanged 6th (CHj) ₁ Si CH, CH ₁ ~ CxHp 1 50 34 90 unchanged unchanged 7th (CHj) ₁ Si CH ₁ CH ₁ -CH JjH ₄₅ 1 50 50 unchanged unchanged 8th (CH,), Si C] I, CH ₁ -CHj, _s H _4l) " 1 50 50 50 unchanged unchanged 9 (CH ₁ J ₁ Si 50 mol% C ₁₁ U _n 65 2 (continued) CH ₁ 50 mol% - (CHj) ₁ OCOCpH ₁ , ^C Ä) unchanged Tabel Composition of Test result R ¹ CH, Separating agents according to the invention ίί Separating unchanged R ^: value (CHJ ₁ Si I. 60 10 50 mol% C,> ll _<( (CHj) ₁ Si 50 mole percent - ("CHj) ₁ OCOCpH ₁₅ 1 50 II (CHj) ₁ Si - (CHj) ₁ OC ₁₁ Hp 1 35 12th (CH ₁ J ₁ Si - (CHj) ₁ OCJjH ₄ , 1 70 13th - - (CHjJjOCijHjs 0 70 14th (CH ₁ ), Si - (CHj) ₁₁₁ COOCH, 1 35 15th C ₂ H ₅ - (CH ₂ J ₁ I ₁ COOCH, 1 40 16 (CH ₁ J ₁ Si - (CHj) ₁₁₁ COOCH ₁ 1 55 17th (CH ₁ J ₁ Si - (CH ₂ ) H ₁ COOCH ₁ 1 30th 18th 50 mole percent CH ₁ (CH ₁ J ₁ Si 50 mol% - (CHj) I ₁₁ COOCH ₁ 1 55 19th 50 mole% C ₁₁ Hp (CH ₁ J ₁ Si 50 mole% - (CHj) ₁₁₁ COOCH ₁ 1 55 20th 75 MoI-VoCj ₂ H ₄₅ 25 mol% - (CHj) ₁₁₁ COOCH ₁

From CH-PS 5 34 732 and from DE-AS 12 73 104 are organopolysiloxane-containing mold release agents or release agent known. However, these release agents are used as external release agents. According to the invention As shown at the beginning, the special organosilicon compounds are used as internal release agents used. Internal release agents are defined as release agents that affect the resins or their solutions can be added. In contrast, external release agents are those that act on the surface of one too demoulding body are applied.

Internal and external release agents are not interchangeable, i.e. an external release agent is not necessarily an internal release agent and vice versa. This is illustrated by the following comparison proven:

The release agent preparation according to Example 1 of CH-PS 5 34 732 was as in the example of the present Application described converted into emulsion form. The example described in the application was with reworked this emulsion and determined the release value. The cutoff value was 150. It is therefore significantly worse than the separation value of the compounds to be used according to the invention and is even lower above the cut-off value of the so-called 0 test. This means that when using the preparation according to CH-PS 5 34 732, Example 1, even a certain adhesive effect occurs.

From this example it is clear that the external release agent is not readily available as an internal one Release agent can use.

Claims (1)

Claim: Use of compounds of the general formula R ³ Si — O — R ² R !.