DE1419970A1 - Organopolysiloxane compositions for the production of - sticky substances repellent - coatings on solid organic surfaces - Google Patents

Description

Lawyer L l-.ürissi

Munich 23, Clemensstr. 26th
In Gen. Power of Attorney for

Dow Corning A.G.

Basel / Switzerland 1419970

No. 14Ο / ΘΟ

PT 419 970.3 Munich, February 13, 1968

Dr Ru/Ve

DO 727/444

Organopolysiloxane compositions for the production of - sticky substances repellent - coatings on solid organic surfaces

It is already known that paper and other organic materials can be treated with organopolysiloxanes to prevent that sticky substances adhere to these substances. Such papers treated with siloxanes, plastics based vinyl compounds, synthetic fibers and the like can be used as intermediate layers for adhesive tapes and for packaging sticky products are used. The preferred siloxanes previously used for this purpose have been methyl hydrogen polysiloxanes or liquid dimethylsiloxanes which are end-blocked by trimethylsiloxy groups and combinations of these Fabrics. It is also already known that mixtures of hydroxyl groups Dimethyl polysiloxanes and methyl hydrogen polysiloxanes, containing at least 5 percent by weight of the methyl hydrogen polysiloxane to be used for treating paper.

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All of these agents have the effect of breaking the adhesive effect of sticky substances on paper, but they suffer with the great disadvantage that some of the siloxane is transferred from one layer of paper to the other when the paper is rolled up "

The transition of siloxane from one side of the paper to the other was, on the other hand, the reason why one hitherto Failed to use siloxane treated paper to make laminated paper articles. This is how we make many species, for example of paper containers glued to cardboard by means of an adhesive. But if the paper is previously coated with a siloxane has been treated that has gotten onto both sides of the paper, it can no longer be glued on successfully, because it comes off the cardboard. If, on the other hand, a siloxane is applied to one side of the paper could, without the siloxane being transferred to the other side of the paper, it would be possible to use the untreated side of the paper. Cardboard boxes or other boxes could also be glued on from such a paper Make paper in which the treated paper side is on the inside of the cardboard and thus

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sticky substances packed in the box do not adhere to its walls. Such a box would be for the packaging of materials such as frozen food, asphalt, rubber, resins, tar and others sticky substances extremely beneficial. The invention now enables such containers to be produced.

The invention provides for the manufacture of thermosetting organopolysiloxane in solution or aqueous dispersion - repellent to tacky substances, -.. Coatings on organic solid surfaces, the mixtures represent from 0.1 to 5 weight polysiloxanes ^ methyl hydrogen and 95 to 99.9 ^c /> Organopolysiloxanes with at least 100 cSt / 25 ° C, which essentially consist of units of the lormel (GH-,) SiO. consist, where χ has a value from 1.9 to

j X 4-X

T "
2 and the optional curing catalysts and 0.01 2 wt. $ Of a carboxylic acid, based on the total mass, with the characteristic that practically all molecules of the organopolysiloxane used, which consists of units of the formula (CH _x ) SiO.

consists, carry at least two Si-bonded alkoxy radicals with less than 5 carbon atoms, some of which are hydroxyl groups can be replaced.

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The solution or emulsion preferably has an organopolysiloxane content of 1 to 10% by weight . The "treated surface, especially paper, should have at least 0.1% by weight of siloxane. The upper limit of the amount of siloxane is not decisive, but the use of more than 5% by weight of siloxane does not bring any particular advantages»

The use of a catalyst is advantageous in order to achieve faster curing. Preferably one uses Metal salts of carboxylic acids, such as lead octoate, dibutyltin diacetate, dibutyltin dilaurate, zinc octoate, iron III octoate, Ferric naphthenate or cobalt naphthenate.

If paper is to be treated on one side, the siloxane solution or emulsion is preferably used the paper coming from the size press is sprayed on. The paper can then be fed over drying drums where the siloxane hardens, then rolled up and stored for a long time without the siloxane coating transfers to the untreated surface.

The amount of the methyl hydrogen polysiloxane must be 0.1 to less than $ 5 wt., calculated on the weight of the total

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909818/0964

ten siloxanes, ". If less than 0.1% by weight is used, so the hardening of the siloxane on the paper is too slow for practical purposes. Is that siloxane but not fully cured, a transfer takes place of siloxane instead. In addition, there is insufficient Hardening of the siloxane has only a low release effect. The "viscosity of the methylhydrogensiloxane is not decisive.

If the amount of methylhydrogen siloxane is 5 ° or more, the separating effect is also only slight. The word "methylhydrogen polysiloxane" used here is intended to include both siloxanes with units of the formula CH ^ HSiO and mixed polymers made of units of the formula CEzHSiO and (OH, .), SiO _1/2 denote -. * ~

The Si-bonded hydrogen used according to the invention free organopolysiloxanes, alkoxylated homopolymers of dimethylsiloxanes, alkoxylated mixed polymers, from dimethylsiloxane and monomethylsiloxane, as well as the homopolymers or copolymers mentioned containing both alkoxy radicals and hydroxyl groups. In any case

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Practically all molecules must have at least two Si-bonded alkoxy radicals or alkoxy radicals and hydroxyl groups. The expression "practically all" means that small amounts of siloxanes which contain neither Si-bonded hydroxyl groups nor Si-bonded alkoxy radicals and which are usually "present in the production of hydroxyl-containing and / or alkoxylated siloxanes" can be present. However, if the amount of siloxane free of hydroxyl groups and alkoxy radicals exceeds 5 Ms 10 fo , then there is little hardening and thus siloxane transfer.

The organobolysiloxanes to be used according to the invention

(GH3) 2 52 ^H 3) 2 ~ CH3 ^ have the formula RO (SiO) ^ GH ^ or RO (SiO) - (SiO) H or

are mixtures of molecules of the types mentioned with or without molecules of the permein HO [(CH ₃ ) ₂ Si0J _n H and H0 [(OH _x ) _o Si0GH, Si (OH) O] H, where R is the methyl, ethyl, Is propyl or butyl. The presence of alkoxy groups has a stabilizing effect on the resulting mixture, since it counteracts gel formation on prolonged standing. It is known that in the case of siloxanes which only have hydroxyl groups as functional groups, the curing takes place very quickly, but the storage stability and the stability in solution form are very low. Siloxanes,

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BATH

which only contain alkoxy groups have a slightly longer one Cure time but excellent shelf life and durability as solutions. The amounts of hydroxyl group- ■ pen and alkoxy radicals in the siloxane used according to the invention can be tuned in such a way that optimal properties are obtained for all application conditions.

The siloxane mixture generally has a viscosity between 100 cP and 500,000 egg? and is best called watery Emulsion applied. For this purpose, the mixture can be emulsified with water in the usual manner. The emulsion should generally have a concentration of 1 to 10 wt. # Siloxane, but higher can be used if necessary Concentrations used

If a catalyst is added to the emulsion, it must the latter should be used within a reasonable period of time, otherwise the siloxane will become part of the emulsion settles and an undesirable product is created. However, it has been found that when small amounts of Carboxylic acids to the emulsion, the stability of which is significantly increased. For this purpose, Bs is any carboxylic acid suitable; it is used in an amount from 0.01 to

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2 & ew. $, Calculated on the weight of the emulsion, applied. Preferably, however, the acid is volatile so that it will work with the water in curing the siloxane Will get removed. Acetic, formic, propionic, octane and 2-ethylhexanoic acid are therefore preferred. at The use of alkoxylated siloxanes is the only There is less need to use these acidic stabilizers.

If the siloxane mixture has a viscosity of 500,000 cP or more, it is expedient in the form of a solution used. However, it is also possible, if appropriate, to use an emulsion produced from such a solution. On the other hand, it is necessary to use solutions for certain types of paper, such as glassine. It it has also been found that higher molecular weight solutions of the siloxanes give better results than with solutions of lower molecular weight siloxanes.

The siloxane mixtures can optionally be used in conjunction with other organic plastics. At the most effective are those that have a deposit of the or-

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ganopolysiloxane on the surface of treated paper cause. The use of other organic plastics has two beneficial effects »In the case of porous Paper, such as Kraft paper, delays or prevents the absorption of des-siloxane by the paper, so that more remains Siloxane on the paper surface and the repellency is thus increased for any given amount of resin. aside from that this means that less siloxane is required to achieve a certain anti-stick effect.

Such organic plastics are mainly curable aldehyde resins, such as aminoplast resins, for example melamine-formaldehyde or urea-formaldehyde resins, and phenolaldehyde resins, for example phenol-formaldehyde resins, these can be water-soluble or also solvent-soluble.

The relationship between the organosiloxane blend and the organic Plastic is not of decisive importance and can fluctuate within wide limits.

The organopolysiloxane compositions according to the invention are suitable for all types of paper, such as glassine, transparent paper, Kraft paper, tissue paper. The treated papers are suitable for the production of all types of containers and are above all

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extremely advantageous "in the manufacture of" coated Containers with an anti-sticking effect on the inside. They can also be used to advantage for treatment the surfaces of organic plastics, such as polyamides, polyacrylonitrile, terephthalic acid alkylene glycol ester, cell glass or vinyl polymers.

example

A number of mixes were made, one of which each 3 G-sw, ^ of a liquid, with trimethylsiloxy groups end-blocked methylhydrogen polysiloxane contained.

I mixture also contained 97 wt. ^ A "liquid from 1200 to IJGO cS.t / ² ° 5 'consisting of (1) 87 parts by weight of a linear Bimethylpolysiloxans of about 2000 cSt / 25 ^0, where 73 i ° of the end-blocking units containing methoxy and $ 27> hydroxyl groups, and (2) 10 parts by weight of a liquid, hydroxy-end blocked Dimethy! polysiloxane of about 40 cSt / 25 ^0, the 3.25 wt. i »Si-bonded hydroxyl groups was obtained.

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Mixture II difference derived from composition I in that the units of the endblockerenden Dimethy! Polysiloxane containing (1) 47 fo methoxy groups and 53 ° f hydroxyl groups.

In the mixtures III and IY the Diinethylpolysiloxan (1) in the end-blocking units about 80 ethoxy fo "or n-butoxy and about 20 hydroxyl groups contained fo.

Mixture V contained 9.7% by weight of a liquid mixture having a viscosity of approximately 2700 cSt / 25 °, consisting of (1) 87% by weight. Parts of a linear Pimethylpolysiloxans a viscosity of about 5000 eSt / 25 ^o ? where more than 60 $ of the end-blocking) units Isopropojqrreste and the other end-blocking units hydroxyl eatliielteiii, \: tA (2) IG hone thy of hydroxyl Dime above polysiloxane on 40 cSt!?.

These 5 mixtures were each in a mixture of toluene and perchlorethylene dissolved. From each of the solutions containing 80 wt. ^ Containing siloxane, a 40 wt. ^ Ige Organopolysiloxane-in-water emulsion manufactured? the emulsions were then each diluted to 1% by weight of organopolysiloxane. Then a Emulsion of zinc oetoate and dibutyltin diacetate in such Amount added so that 2% by weight of zinc and 0.54% by weight of tin are

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counts on the weight of the organopolysiloxane in the Emulsion. Each of the emulsions was then applied to bleached parchment paper and for 2 minutes heated to 115 °. With the help of a 2.5 cm wide medical adhesive tape that is printed with 0.018 kg / cm was pressed onto the paper at a temperature of 70 ° for 6 days, its anti-stick properties became as well as the still existing adhesion or siloxane transfer checked. The one to peel off the strip at a speed of 30.5 cm per minute at an angle of 180 ° from the various treated The force required for the types of paper was determined with the aid of a spring balance and is given in the table.

Mixture anti-stick effect high existing

(g / 2.5 cm) adhesion

(g / 2.5 cm)

IO ⁺ 265

II 5 190

III O ⁺ 155

IV 3 115

V 5 120

/ too small to be measured

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Similar results are obtained when using a mixture of 3% by weight of a liquid end-blocked with trimethylsiloxy groups Methyl hydrogen polysiloxane and 97 percent by weight of one Dimethylpolysiloxane completely end-blocked with methoxy groups of 2000 cSt is used.

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Claims (2)

-H- claims 1. Thermosetting organopolysiloxane compositions in solution or aqueous dispersion for the production of - coatings on solid organic surfaces, which are mixtures of 0.1 to 5 percent by weight. Polysiloxanes $ methyl hydrogen and 95 to 99.9 wt.% Organopolysiloxanes having at least 100 cSt / 25 C, consisting essentially of units of formula (GH _x) SiO. consist, where χ has a value of 1.9 to 2 - and the optionally curing catalysts and 0.01-2 wt. ^ a carboxylic acid, based on the total mass, characterized ge denotes that practically all molecules of the organopolysiloxane used, which is made up of units of the formula (CH. *) SiO. exists, at least j X 4 ~ X two Si-bonded alkoxy radicals with fewer than 5 carbon atoms carry, some of which can be replaced by hydroxyl groups. 2. organopolysiloxane compositions according to claim 1, additionally containing curable aldehyde resins. 9098 18/0964
Current documents (Art. 7 ,, _Para . _{2 N} ,, _{Sat2 3} ^ _{,. NdemnasBC3} . _{V 4 9 iü}