NO170026B - APPLICATION OF POWDER POLYMERISATES OF (MET) ACRYLIC ACID DERIVATIVES AND SILICONE RESINES FOR THE PROTECTION OF MINERAL BUILDING MATERIALS - Google Patents

Description

The present invention relates to the use of graft polymers of methacrylic acid derivatives and alkoxy-functional silicone resins as impregnation agents, especially for building protection.

More specifically, the invention relates to the use of a grafting polymer which hardens in the presence of moisture and which is obtained by free radical polymerization of

a) 10-90 wt-56 of an alkoxy-functional silicone resin of the formula:

there

x - 0.75-1.7;

y - 0.2-2;

R denotes a straight or branched alkyl residue with 1-20 carbon atoms, an alkaryl residue or an unsubstituted or

substituted aryl radical with up to 20 carbon atoms; and

R' means a straight or branched alkyl residue with 1-18 carbon atoms, and

b) 90-01 weight # of a mixture of components essentially consisting of

i) (meth)acrylic acids selected from the group of acrylic acid and

methacrylic acid,

ii) alkyl ester derivatives of such acrylic and such methacrylic acid; and

iii) OH-functional derivatives of said acrylic or methacrylic acid,

where the sum of a) + b) is always 100 weight-$6.

The use of silicone resins of different composition as impregnation, hydrophobicizing and building protection agents has been known for a long time. Particularly advantageous here are alkoxy-functional oligomeric siloxanes which cross-link under the influence of moisture, possibly in the presence of a catalyst.

Furthermore, the use of mixtures consisting of copolymers of methacrylic acid methyl ester and of silicone resins is known from DE-OS 2 150 736, DE-OS 2 352 242 and DE-AS 1 671 280 for pigmented coating agents or impregnating agents. The advantage of such mixtures lies in the simple preparation method, the disadvantage is more serious and consists in a narrowly limited compatibility between silicone resin and polymethyl methacrylate.

This incompatibility between the polymers inevitably leads to a separation of the mixture components during film formation and penetration into the building material. In order to limit the incompatibility and separation tendency of the components, firstly aromatic solvents are required and secondly an application from highly diluted solution.

Combinations of siloxane resins and acrylate resins are highly desirable. However, in addition to high water repellency, silicone resins also have excellent water vapor permeability, while acrylate resins ensure better pigment binding and better protection against, for example, carbonation. On the other hand, the water vapor permeability of acrylate or methacrylate copolymer fibers is low.

Applying and impregnating agents which combine the advantages of both systems, and consist of compatible, non-separable, well hydrolysis-resistant combinations are therefore very advantageous and desirable.

The task of the invention was to provide compatible silicone-acrylate resin combinations for cross-linking impregnating agents and facade coating agents with the help of ambient humidity.

As mentioned, the task is solved by using hydrolysis-stable cross-linked alkoxysilicone resin (meth)acrylate grafting polymers of the type mentioned at the outset.

This task is solved, as indicated above, by using grafting polymers of methacrylic acid derivatives and silicone resins of the type mentioned at the outset.

The silicone resins used as grafting bases are known products, the preparation of which is described in W. Noll, "Chemie und Technologie der Silicone", 2nd edition, Verlag Chemie, Weinheim, 1968, page 551 et seq. Optionally, methoxy, ethoxy, isopropoxy or butoxy groups may be present as alkoxy groups. For economic reasons and because of their high reactivity, the methoxy groups are therefore particularly preferred. In the same way, the silicone resins contain on the silicon atom next to methyl and phenyl, alkyl substituents with linear or branched chains of the general formula CnH2n+\ with n - 2-20. Particularly preferred are such silicone resins which have branched alkyl substituents at the Si atom. Furthermore, the silicone resins can contain tri- or tetra-functional branching sites. The viscosity of solutions of these resins are alcohols or hydrocarbons is low to ensure good penetration, for example in building materials. In the case of a solids portion after hydrolysis of the alkoxy groups of 60-65 wt-St, the viscosity of the preferably used solutions is below 2,000 mPa*s, preferably below 200 mPa*s.

Solvents are preferably aromatic hydrocarbons, aliphatic hydrocarbons, alcohols such as ethanol or isopropanol, esters such as butyl acetate or their mixtures.

Examples of monomers that can be used for the grafting reaction include acrylic acid, methacrylic acid and their derivatives, preferably their alkyl esters. As alkyl esters, mention must be made of methyl, ethyl, isopropyl, propyl, n-butyl, isobutyl and higher alkyl esters with up to 25 C atoms in the alkyl component. OH-functional ester derivatives of acrylic and methacrylic acid are also used. Special effects can be achieved by copolymerizing any mixtures of vinyl aromatics such as styrene or α-methylstyrene, (meth)acrylonitrile, (methacrylic acid or vinyl acetate, α-olefins, allyl and isopropenyl compounds or their polyfunctional derivatives with (meth)acrylic acid alkyl esters.

The polymerization can be started with the help of the known radical initiators based on azo compounds or peroxide compounds such as dibenzoyl peroxide, 4,4'-dichlorobenzoyl peroxide, di-tert.-butyl peroxide, dicumyl peare oxide, tert.-butyl pivalate, tert.-butyl peroctoate . can further be triggered photo-chemically or by radiation activation. The polymerization is carried out in solution or without solvent addition. As solvents, the already mentioned aliphatic or aromatic hydrocarbons, alcohols, ketones or esters are to be mentioned. Solvents or solvent mixtures whose flash point according to DIN is above 21 are preferred <*>C.

The molecular weight of the graft polymer components is controlled by the reaction temperature, solvent, initiator type and

-amount and possibly by molecular weight regulator. Even the grafting reaction and the grafting yield can be controlled by grafting activators. Grafting activators include grafting and transfer-active monomers. Allyl compounds such as allyl alcohol, allyl acetate and other allyl esters of aliphatic or aromatic carboxylic acids, allyl carbonate derivatives, diallyl and polyallyl compounds such as diallyl phthalate, triallyl cyanurate, triallyl citrate, allyl ethers and diallyl ethers should be mentioned as grafting activators. Important grafting activators are further vinyl acetate, acrylonitrile, vinyl chloride, ethylene, propene, isobutylene or butene-1 and diisobutene

tylene as examples from the series of active α-olefins. The grafting reaction according to the invention is preferably carried out using 0.01 to 20 weight-*, calculated on the total sum of the used reaction components of grafting activators, and also the thus formed products and the thus carried out method are covered by the invention.

The grafting reaction succeeds in combining the 1 and individually incompatible acrylate and alkoxysiloxane resin components into a clear film-compatible coating resin.

The already mentioned mixtures of special silicone resins (DE-OS 2 352 242) and the polymethacrylic acid methyl esters (DE-AS 1 671 280) can only be used from special solvent combinations with a low solids content or only in certain combinations as facade protection paint. Physically, it involves mixtures of incompatible polymers. With the grafting reaction, a drastic improvement in the compatibility of the silicone resin and acrylate resin components is achievable. By bonding the grafting resin components to the silicone resin via a hydrolysis-stable Si-C bond, a separation of the silicone and acrylate resin components is further avoided, so that the building material is also sufficiently protected in the overall penetration area. Furthermore, by mixing the grafting polymer solution with inorganic or organic color pigments which takes place under the conditions usual in the art, it is possible to obtain a pigmented coating agent with high color tone resistance and gloss attainment.

The impregnating and coating agents used according to the invention are cross-linkable by ambient humidity. Catalysts are used to accelerate the crosslinking reaction. These catalysts are known and are discussed, for example, in W. Noll, "Chemie und Technologie der Silicone", 2nd edition 1968, page 155 ff. Generally, soluble organometallic compounds such as Sn, Mn or Fe derivatives are used as cross-linking catalysts. The amount of catalyst, calculated on a solid basis, depends on various factors such as substituents, desired film hardness and curing time and usually amounts to 0.01-5 weight-*, preferably 0.5-2 weight-*.

The grafting polymers used according to the invention are used as an impregnation agent for building materials made of concrete, and also as facade paints.

The object of the invention shall be explained in more detail with the help of some examples.

For the tests described below, silicone resins corresponding to the following formulas are used:

Silicone resin A: (Me)0f7(i-Bu)0.381(0t05(OMe)0.9

Me - methyl residue

i-Bu - isobutyl residue

Silicone resin B: MeSi(0) ±f x(OMe)0>8

Silicone resin C: (Me) 1>0R0,2R'0,1S1(°)l,o(°Me)o,7

R - <C>12"alkyl radical

R' - C14 alkyl radical

The solids content stated in the example is determined after cleavage of the alkoxy groups by hydrolysis of the alkoxy groups, by hydrolysis with the aid of alcoholic hydrochloric acid, evaporation of the acid and the volatile part over 3 hours at 105° C in a drying cabinet.

Unless otherwise stated, the viscosity of the graft polymer solutions has been measured by Haake viscometer at 23<*>C.

Example 1;

During nitrogen transfer is heated

11 kg silicone resin A (100*-ig)

2.5 kg of test petrol (petrol fraction with boiling point range 155-185°C)

to 100<*>C.

Then, 2 solutions are pumped in simultaneously and evenly over the course of 2 hours:

Solution 1: 5.1 kg of isobutyl methacrylate

1.0 kg of n-butyl acrylate

1.0 kg of hydroxypropyl methacrylate

Solution 2: 4.4 kg of sample petrol (petrol fraction 155-185'C)

0.2 kg tert-butyl peroctoate 0.25 kg di-tert-butyl peroxide

The reaction is then carried to completion

1 hour at 120°C

and 2 hours at 130°C.

After cooling, catalyze with 150 g of dibutyltin dilaurate. The product then has a viscosity of 172 mPa*s and a solids content of 60.5*. A film produced with this solution is highly transparent, shows excellent barrier properties against water and CO2 and has high water vapor permeability.

Example 2:

In a 5 liter reactor, 1.6 kg of silicone resin A is heated to 112°C under nitrogen

0.4 kg of test petrol (petrol fraction 155-185°C).

Solutions 1 and 2 are pumped in During 2 hours:

Solution 1: 800 g of isobutyl methacrylate

200 g of methyl methacrylate

175 g of n-butyl acrylate

150 g of e-hydroxyethyl methacrylate

Solution 2: 1 kg of sample gasoline

35 g tert-butyl peroctoate

After the addition has been completed, the mixture is stirred for a total of 12 hours at 112°C and 1 hour at 120°C.

After cooling, the product has a solids content of 61.0 wt-* and a viscosity of 1,700 mPa*s. After adding 0.5 weight*, referred to solids content, of dibutyltin dilaurate, the film is completely cured and highly transparent after 24 hours.

Example 3:

Investigation as a water-repellent impregnating agent for mineral building materials.

A graft polymer produced according to the above-mentioned method with the composition listed in example 1 is diluted with test petrol to approx. 9 weight-*. Samples of different building materials are produced by dipping them once into the impregnation solution. The dipping time is 30 seconds. The samples thus prepared are stored for 6 days at 23°C and about 50° relative humidity and are then dried at 50°C for 24 hours.

The capillary absorption of water is then determined at an immersion depth of 3 mm.

Compared to the untreated specimens (values in brackets), the following results are obtained:

From the values it can be seen that the untreated building materials are already water-saturated after 2 hours, while the specimens treated with the grafting polymer according to the invention showed only a slight increase in weight even after 24 hours of water storage.

Example 3a

The experiment from example 3 is repeated using a 9# solution of a resin produced by polymerization of Isobutyl methacrylate.

From the values, it can be seen that the good hydrophobicity demonstrated in example 3 is not achieved.

Example 4

Examination of water vapor and carbon dioxide permeability.

Examination of the diffusion resistance figures jj takes place 1 in accordance with DIN 53 122 and gives, when using solutions of the graft polymers from example 3, the following values

jj E2O 2,460

\ x C02 2,350,000

Example 4a (comparison experiment)

The examination of example 4 is repeated using a commercially available impregnating agent based on polysiloxane (A) as well as the isobutyl methacrylate polymer used in example 3a

(B).

The values found show that the grafting polymer used according to the invention resists the penetration of carbon dioxide into the building material very well, while the water permeability is hardly hindered. This property profile is desirable (avoidance of carbonisation damage).

From the comparison tests, it can be seen that commercial impregnation agents on a polysiloxane basis do not have carbonation protection, while pure polyacrylate resins do indeed show sufficient carbonation protection, but not the high water vapor permeability required for building protection.

Literature: R. Engelfried "Defazet" Heft 9 - 1977, pages 353-359.

Example 5

Production of a pigmented building protection varnish.

The good building physical properties demonstrated in examples 3 and 4 enable the production of a pigmented facade coating, which is, for example, produced according to the following recipe:

Grafting polymer

60*-ig solution in test petrol 300.00 parts by weight Titanium dioxide Rutile type 75.59 parts by weight Iron oxide pigment (yellow) 5.94 parts by weight Iron oxide pigment (black) 5.94 parts by weight Chromium oxide green 1.84 parts by weight Talc 56 .69 parts by weight Solvent for correction of

viscosity 40 to 100.00 parts by weight

The application takes place by ironing. 2 coats are applied at intervals of 24 hours. The dry film thickness amounts to 80 to 120 pm. The examination in a short-term climate impact device according to DIN 53 231 shows no visible change after a test period of 2,000 hours.

Claims (1)

1. Use of grafting polymers which harden in the presence of moisture, where the grafting polymer is obtained by free radical polymerization of a) 10-90 weight-* of an alkoxy-functional silicone resin with the formula: there x = 0.75-1.7; y = 0.2-2; R denotes a straight or branched alkyl residue with 1-20 carbons atoms, an alkaryl radical or an unsubstituted or substituted aryl radical with up to 20 carbon atoms; and R' means a straight or branched alkyl residue with 1-18 carbon atoms, and b) 90-01 weight-* of a mixture of components essentially consisting of i) (meth)acrylic acids selected from the group of acrylic acid and methacrylic acid, ii ) alkyl ester derivatives of such acrylic and such methacrylic acid; and ili) OH-functional derivatives of said acrylic or methacrylic acid, where the sum of a) + b) is always 100 weight-*, as an impregnating agent, especially for the protection of mineral building materials.