DE1669940A1 - Process for the preparation of organopolysiloxane elastomers - Google Patents

Description

MUnohen, December 20, 1966 Dr.Wg

DC 1305/790

Process for the preparation of organopolyalloxane elastomers

Organopolyslloxane elastomers cured at room temperature in the presence of silicic acid esters have been around for some time Years known. It is also known that by mixing hydroxyl-containing siloxanes with Kiese1-acid alkyl esters or alkoxysilanes in the presence of catalysts containing metals, curing at room temperature takes place with the formation of elastomers. These products are of great economic importance in use for embedding, sealing and coatings. Such molding compositions which harden at room temperature to give elastomers are generally referred to as ^ -component masses " known as a catalyst, crosslinker and organopolysiloxane should only be mixed shortly before use. The main disadvantages of such cure to elastomers at room temperature However, 2-component-Maseen are relatively insignificant physical properties, especially their extraordinary

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Very poor tear resistance and poor adhesion to metal substrates. For example, the known elastomers made from 2-component compounds of the type mentioned generally have resistance values (standard body B) in the order of magnitude of ~ Z> _t 6 to 5 A kg / cm (20 to 30 pounds / inch) and peel strength values of around 0 , 72 kg / cm (4 pounds per inch).

It is also known that elastomers can be formed at room temperature One-component compounds based on organo polyslloxane hardening with high strength by mixing hydroxyl groups containing polysiloxanes with certain types of carbon black as fillers and certain ketoximesilanes can be obtained. One-component compositions which can be hardened to give elastomers have the disadvantage, however, that they are insufficient in deep layers Cure through, as there is not enough moisture in these areas for curing.

The present invention therefore relates to a process for the production of elastomeric moldings based on organopolysiloxane with high tear resistance and sole strength, which are well hardened even in deep layers.

The inventive method for the preparation of organopolysiloxane elastomers from Dl containing hydroxyl groups

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BATH ORIGINAL

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organopolyniloxanes, fillers and crosslinking agents in Presence of curing catalysts with shaping by crosslinking, is characterized in that such cash registers be stopped on 100 parts by weight of the hydroxyl groups containing diorganopolysiloxanes (A) with a Viekositfit of at least 5.CCO cSt./25 ° C, 20 to 50 parts by weight a type of carbon black (B) having an average particle diameter of less than 50 millimicrons and a structural index from 120 to 200, as a filler, 2 to 10 ow parts Silanes (C) of the general formula

and / or their partial hydrolysates, in which R is monovalent * given optionally halogenated hydrocarbon radicals, R * optionally halogenated hydrocarbon or «^ -alkoxyalkyl radicals with 1 to 8 carbon atoms and η is an integer from 0 to 1 inclusive, as a crosslinking agent and Curing catalysts (D) contain, (A) with (B) before Addition of (C) and (D) has been mixed.

In order to achieve the improved properties of the elastomers which can be produced according to the invention, it is important that the

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Crosslinking agent (C) and the catalyst (D) with the polysiloxane Rulgeaisoh be frozen shortly before the hardening. When either the crosslinking agent or the catalyst ait the Ruiart have been in touch too long before the shepherds " the end product has poorer physical properties.

The best way to carry out the invention Procedure i »operation consists in both a premix

the polysiloxanes (A) and the Ruflart (B), as auoh one Preparation of the crosslinking agent (C) and the catalyst (D) beforehand. These two preliminary solutions can then stored separately until susi Veraisohen. When adding, hardening takes place through the action of air humidity. Optionally, the crosslinking agent (C) and the catalyst (D) can also be used without prior notice, but practically at the same time de »Folyslloxan-Fttllstoff-Oe- ■ Isoh be added shortly before the Oesaisohung is exposed to humidity or otherwise hardened.

The hydroxyl groups used in the process of the invention containing Dlorganopolysiloxane can old any of the known monovalent hydrocarbon or halogenated hydrocarbon radicals.

_m . BATH ORIGINAL

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se. B. with aliphatic radicals, such as methyl, xthyl, ootadeoyl, Vinyl, allyl and isopropyl moieties Hydrocarbon radicals such as cyelopentyl, cyclohexyl, cyolohexenyl and Methyloyolohexylrestenj aryl hydrocarbon residues, such as phenyl, tolyl, xenyl and vaphthyl radicals and Arylalkyl hydrocarbon radicals, such as benzyl, fl-phenyl-ethyl and fl-phenylpropyl radicals. The substituents can also be any halogenated hydrocarbon radicals, such as chloroethyl - ^ - chloropropyl, 3,3,3-trifluoropropyl, chlorophenyl, Bronphenyl and «, <x» <* - trlfluorotolyl radicals. Hydroxyl groups Diethylpolysiloxanes containing dietary agents are preferred.

It should be noted that the Dlorganopolysiloxane low Amounts of non-substituted, trisubstituted and unsubstituted May contain siloxane helices.

To achieve the excellence of the genes according to the invention Obtained blastoawren is the addition of fillers in the specified quantities and with the specified durohsohnittliohen Teilohendurohaetser of decisive, of importance. With soot, whose particles are larger, as defined above, the good properties are not achieved. The structure index of the call type is a height value, the dea value for the measurement of the oil absorption of the call type, divided by the value for the measurement of the oil absorption a norealeu Kiafart of the same part size

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will. The structure index is therefore a measure of the small aggloneration of a certain type of rufi. It was found that Rufl varieties with structural indices below the specified Values only give insufficient reinforcement, while those with structural indices of over 200 give molding compounds that are not extrudable and have a very poor shelf life.

Details on the structure of Ruflarten are in the reference "Introduction to Rubber Technology" by Maurice Morton (1959) on pages 192-196.

As an example for the determination of the structure index, the following is given on page 196 of the cited reference: A species of rufl with a particle size of 51.9 millimicrons and an oil absorption of 140 ml per 100 g should be high Structure as the normal ülabsorbticn for carbon this particle size is about 82 ml per 100. The structure index is calculated from this as follows1

1 * 0 χ 100 _{1 <yn}

As VsjTiietxungamitti. (C) can%> el the invention

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Any method of the defined o-KieeeleMureeeter or their partial hydrolytes or silanes are monovalent, if appropriate halogenate hydrocarbon radicals per SI atom and their partial hydrolytes are used. Examples are o-KioselsKureKthyl-, -propyl-, -laopropyl-, -octyl-, - • -chlorlthyl-, -allyl-, -hexenyl-, -cyolohexyl-, -phenyl- « -benzyl-, -onlorphenyl-, - • -Mthoxjttthoxy- and fl-Mthoxy-Kthoxyeater, as well as the o-silicic acid ester from Pornel

Examples of silane bonding tools are methyltriaethoxyrsilane, XthyltriKthoxysilan, Fhenyltrläthoxyeilan, Chlorophenyltributoxysilan, Trifluoropropyltrieethoxysilane and Methyl-tri- (l-s * thoxyltboxy) -sllane. As a networking tool (C) 1st o-Silicic acid propyl ester prevents Auterdea the Vernetxungssdttel also TellhTdroljreate the o-KleselsKureester or the defined silanes. These partial hydrolytes "Usaen luslloh" tin and on some of the Si-Atoee nooh have hydrolyzable groups.

Old hardening catalysts (D) ketones in the case of the invention ■ No method is used that is responsible for the reaction an alkoxre old water or old a Si-bonded Accelerate hydroxyl group failure. Typical representative

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The Boloher catalysts are carboxylic acid salts of metals such as dibutyltin diacetate, dibutyltin dioctoate, stannous octoate, ferric octoate, lead laurate and cobalt naphthenate; Titanium esters such as tetrabutyl titanate, tetraoctyl titanate and tetraisopropyl titanate; and amines such as n-hexylamine; Amine salts "as hexylamine hydrochloride _r, Butylaminacetat and guanidine di-ttthylhexoat. Other effective catalysts are described in US Patents 2,843,555,3,127,363 and 2,927 * 907. Carboxylic acid salts of tin are preferred as catalysts (D).

It is often advantageous "However nioht absolutely necessary" in the Foranassen further constituents incorporate "us the handling of the catalyst-crosslinker mixture z \ x improve or plasticize the polysiloxane Ruflgemisch. Such additives are, for example, liquid siloxanes or thickeners such as hydrogenated castor oil or calcium carbonate. In addition, the molding compositions can contain small amounts of antioxidants, corrosion inhibitors and other commonly used. Organopolysiloxanelaetoaeren contain usable additives.

example 1

By mixing 140 parts by weight of one of the

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gene units containing hydroxyl groups dimethyl polysiloxane with a viscosity of 12,500 oSt./25 ° C, 40 ow parts Soot, with an average particle diameter of 31.9 millimicrons and a structural index of 165.4 ow. parts a phenylmethylpolysiloxane having hydroxyl groups in the terminal units and having a viscosity of 600 cSt./25° C and 1 part by weight of an in the terminal Units of dimethyl polysiloxane containing hydroxyl groups A premix was prepared with a viscosity of 40 cSt./25 ° C. This mixture was heated to 163 ° C for one hour to 177 ° C, heated at a pressure of 63.5 cm Hg, cooled and then marry until they are consecrated. It was called Premix (1) referred to.

By mixing 44 parts by weight of o-silica n-propyl ester, 30 parts by weight of one in the terminal units Triorganosllyl groups containing dirnethylpolysiloxane oil, with a viscosity of 2,000 oSt./25 ° C, 16 parts by weight Calcium carbonate 6 parts by weight of a hydrogenated castor oil and 4 parts by weight of dibutyltin dilaurate became a paste-like one Premix (2) produced which contains the silicic acid crosslinker and the curing catalyst.

Premixes (1) and (2) were in a ratio

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of 10 parts by weight (1) are mixed to 1 part by weight (2) and the molding compound is then exposed to atmospheric humidity at room temperature for seven days. The elastomer obtained had the following properties: hardness measurement (Shore) 30; Tensile strength 36.9 kg / cm (525 P »i); Elongation at break 750 % \ standard body B Tear strength l8 kg / cm (100 lbs./inch).

A sample of this mixture was kept in a tube and passed through a standard nozzle at a rate of extruded from 30 to 40 g per minute. The molding compound still had moisture after exposure to the air a processing tent of about two hours.

Example 2

By mixing 100 parts by weight of a liquid dimethylpolysiloxane containing hydroxyl groups in the terminal units with a viscosity of 12,500 oSt./25 ° C, 26.6 parts by weight of the carbon black from Example 1 and one part by weight a dimethyl polysiloxane containing hydroxyl groups in the terminal units and having a viscosity of 40 cSt./ The premix (3) was prepared at 25 ° C.

The premix (4) was made by mixing 51 parts by weight

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Bhenyltrläthoxyellan, 40 parts by weight of an in the terminal Liquid diroethylpolysiloxane containing units of trlorganosllyl groups, old with a viscosity of 2,000 cSt./ 25 ° C, 11 parts by weight of a hydrogenated castor oil and 4 parts by weight of di-butyl tin diacetate prepared.

The preliminary calculations (3) and (4) were in a ratio of 10 to 1 parts by weight frozen and on the sole for hardening exposed to humidity. Part of the mixture was also hardened in contact with old aluminum liners. That The mixture became at room temperature due to the ingress of moisture hardened in the tents given in the following table:

Tensile strength "peel strength"

Hardness measurement in lcg / on Elongation at break in kg / o » tent (according to Shore) (psl) in % (lbs./In.

24 hours 22 47.8 (68o) 950 12.6 (70 lbs./in.) M 7 days 33 * 9.9 (710) 880 12.6 (70 lbs./in.)

In each case the failure was when peeling off the aluminum lun panel for a cabbage ion failure (i.e., a failure the internal molecular forces that hold the adhesive together cause) to return. Oil proves the award-winning

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ntte adhesion of the elastomer to the aluminum plate. Example 3

This example shows the effect of the amount of soot on the strength speed of the hardened molding compound. In this example, the Mixtures (1) and (2) from Example 1 were used, with the difference that the amount of oil in premix (1) as from can be seen in the following table. In each case the Gemisoh was cured in the specified time and determines the properties of the hardened material:

Weight
Part
of soot Hartwigs -
time in
Taeen hardness
Measurement
(Shore) Tensile strength _O
kelt kg / cor
(d.8.1.) (180) strain
in % Standard body
per B input
Relßfestlg-
kelt in
kg / om
(lbs./in.) (10) Peeling
firm
on
aluminum
in kg / cm
(lbs./in.) (10) 10 3 days 23 12.7 (300) 400 1.8 (22) 1.8 ! (35) 15th 4 days 25th 21.1 (380) 550 3.97 (23) 6.3i (40) 7 days 30th 26.7 (44O ₄ ) 550 4.15 (100) 7.2 <* 5) 20th 5 days 30th 30.9 (580) 650 18.0 (60) 8.1 (45) 7 days 31 40.8 (650) 650 10.8 (130) 8.1 (75) 25th 4 days 27 45.7 (620) 900 23.4 (120) 13.5 (75) 7 days 32 43.6 (740) 950 21.6 13.5 (75) 28.6 7 days 35 52.0 850 13.5

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Example 4

Were the following polysiloxanes containing hydroxyl groups, used instead of the polysiloxanes from the premix (1) from Example 1, so an improved Einreüfestlg-Jcelt obtain:

1. A copolymer of 25 mol * Trlfluorpropylnethylslloxan- and 75 moles * of di-methylsiloxane units

2. A copolymer of 5 mol * diphenylsiloxane and 95 moles of dimethyliloxane units

3. Phenylethylpolyslloxane

4. A MisohpolyMsrisat from 10 mol * Vinylaethyleiloxan- und 90 moles * of theethylsiloxane units

5. A copolymer of 70 mol * xthyleethylsiloxane and 30 mol * ß-phenylpropyl («ethyl) siloxane units.

Example 5

Elastomers with improved tear resistance were included in Use of the following silanes in the pre-processing (2) Example 1 received!

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1. o-Ki «aeleMureMthyl # et * r

2, o-Kl «8« l8lur «allyl88ter

3 * o-Kieeelelure-fl-chloroethyl ester

4. o-Kieetleilur "-fl-" 8thoxyäthoxyeet * r

5. Methyltrim · thoxy »ilane

6. Trifluoropropyltrieethoxyeilane 7 · vinyltriraethoxyellane 8 * chlorophenyltrimthoxysilane 9. Polykylic acid methyl ester

10. Phylmethoxypolyeiloxane

11. Polyki «BtlaMurebutyl # Bter

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Claims (1)

Specimen copy 1 Can not be changed Claim t Process for the preparation of organopolysiloxane elastomers from hydroxyl-containing chloro-organopolysiloxanes, fillers and cross-linking agents in the presence of curing catalysts under shaping through networking, thereby marked «that such masses are hardened» those containing 100 parts by weight of the hydroxyl groups Dlorganopolysiloxane (A) with a viscosity of at least 5,000 cSt./25 ° C, 20 to 50 parts by weight of a type of carbon black (B) with an average part diameter of less than 50 millimicrons and a structural index of 120 to 200, as filler, 2 to 10 parts by weight of silanes (C) of the general formula and / or their partial hydrolysates, in which R is monovalent, optionally halogenated hydrocarbon radicals, R ^{1 is} optionally halogenated hydrocarbon or «^ - alkoxyalkyl create with 1 to 8 carbon atoms and η is an integer from 0 to generally 1, as crosslinking agents and HMrtungekatalyeatoren ( D), where (A) was mixed with (B) before adding (C) and (D). 009845/1719 INSPECTED