DE3144011A1 - Process for prevention of growth on concrete surfaces - Google Patents

Abstract

Growth on concrete surfaces which are under water containing life forms for so long that growth can take place on these surfaces is prevented by a method in which a coating of a material which is crosslinkable to give an elastomer and is based on a diorganopolysiloxane which contains a rod-like copolymer of styrene and n-butyl acrylate, which was produced by copolymerisation of the stated monomers by means of free radicals in the presence of a diorganopolysiloxane, is applied to the surface to be protected from growth and is allowed to undergo crosslinking.

Description

Method for preventing fouling on concrete surfaces

Anti-fouling protective coatings on solid surfaces under water, these coatings containing organopolysiloxane elastomers as an essential binder, are already known. From GB-PS 14 70 465 (published April 14, 1977, The International Paint Company Limited) have known protective coatings of this type . unsatisfactory low mechanical strength. The effort for the production the coatings according to PCT-WO 80/00554 (published April 3, 1980, The International Paint Company Limited) is undesirably high. As a further state of the art are US 42 11 729 (published July 8, 19W0, K.

Marquardt et al., Consortium for Electrochemical Industry GmbH) US 41 33 938 (published January 9, 1979, T. G. Bingham, SWS Silicones Corporation, European Patent Application 00 32 597 (published July 29, 1981, Shell Internationale Research Maatschappiå B.V, and US 40 72 655 (published February 7, 1978, E. Louis et al., Wacker-Chemie GmbH). We will continue to these further publications detailed below.

The task was to find a method for preventing fouling on concrete surfaces that have been under water containing living beings for so long, that fouling can form on these surfaces, with the before fouling protective surface is a coating made of a compound that can be crosslinked to form an elastomer applied and allowed to crosslink to find something that is easily feasible and leads to coatings with high mechanical strength. This task is carried out by solved the invention.

The invention relates to a method for preventing vegetation on concrete surfaces that have been under water containing living beings for so long, that fouling can form on these surfaces, with the before fouling protective surface is a coating made of a compound that can be crosslinked to form an elastomer based on organopolysiloxane is applied and allowed to crosslink, thereby characterized in that the organopolysiloxane in the crosslinkable mass is such, contains the rod-shaped copolymer of styrene and n-butyl acrylate, the by copolymerization of the monomers mentioned by means of free radicals in the presence was generated by the diorganopolysiloxane.

No. 42 11 729 does not recommend any mass which can be crosslinked to form the elastomer Kind used according to the invention for the production of e.g.

Concrete coatings.

US 41 33 938 recommends no coatings on solid surfaces that have been under water containing living beings for so long that Surface growth can form.

European Patent Application 00 32 597 does not mention concrete surfaces.

US 40 72 655 mentions neither styrene nor n-butyl acrylate.

In the case of the concrete surfaces produced by the method according to the invention Can be protected from vegetation, it can be any concrete surface act that have been under water containing living beings for so long that fouling would form on them without proper treatment. Examples of such Surfaces are such lon canal walls made of concrete, of bridge piers Concrete, concrete tanks, including pools, and pipes made of concrete. In the case of the water containing living beings, under which they were treated according to the invention Surfaces, it can be; I mean sea or fresh water that stands or flows, the invention for flowing fresh water of particularly great importance is.

The production of compounds based on base layers that can be crosslinked to form elastomers of diorganopolysiloxane, the rod-shaped copolymer made from styrene and n-butyl acrylate contains, the copolymerization of the monomers mentioned, so styrene and n-Butyl acrylate, at, by means of free radicals in the presence of diorganopolysiloxane has been described many times and does not need to be explained in detail by Laher will. This production is e.g.

.n US 35 55 109 (published January 12, 1971, I, C. Getson,, tauffer-Wacker Silicone Corporation), Examples 6 to 8, US, 7 76 875 (published Dec. 4 1973, I.C. Getson, Stauffer hemical Company), Examples 1 to 4 and Example 6, 8 and 9, is 36 31 087 (published December 28, 1971, R.N. Lewis et al., Htauffer-Wacker-Silicone Corporation) and US 40 32 499 (published June 28, 1977 to F.-H. Kreuzer et al., Consortium for: Lektrochemische Industrie GmbH), Example 6, described in detail. Such compositions are commercially available.

The rod-shaped copolymers which n Presence of diorganopolysiloxane through mixed polymerization by means of free radicals 45 to 75 percent by weight from styrene-derived units and the remainder are units derived from n-butyl acrylate.

preferably the amount of diorganopolysiloxane is 20 to D percent by weight, based on the total weight of diorganopolysiloxane and styrene copolymer and n-butyl acrylate.

In particular because of the easier accessibility are preferred at least 80% of the number of organic radicals in the diorganosiloxane units is methyl radicals.

Preferably, the diorganopolysiloxanes have rod-shaped in their presence Copolymer produced from styrene and n-butyl acrylate is an average Viscosity from 150 to 6000 mPas at 250C.

In the case of the masses used in the process according to the invention, these are so-called one-component systems, i.e. mixtures that are used in ready-mixed form are brought on the market, or so-called two-component systems act that consists of at least two components more or less immediately before the Apply to the surfaces to be protected.

The masses can be crosslinked by condensation or by addition from Si-bonded hydrogen to aliphatic multiple bonds.

In addition to crosslinkable diorganopolysiloxane and in the presence of This diorganopolysiloxane produced copolymer of styrene and n-butyl acrylate as well as crosslinking agents and optionally crosslinking catalyst can be those according to the invention The compositions used and which can be crosslinked to form elastomers may contain other substances. Such other substances are in particular plasticizers, such as esters of phthalic, adipic, Sebacic, citric or phosphoric acid with 3 to 30 carbon atoms per molecule , containing aliphatic or aromatic alcohols. More preferred than such Plasticizers, however, are preferred as plasticizers due to triorganosiloxy groups 1 to 4 carbon atoms ae organic radical, in particular trimethylsiloxy groups, unblocked diorganopolysiloxanes with an average viscosity of 50 until 10,000 mPa.s at 250C. The diorganosiloxane units in these preferred plasticizers can for example simethylsiloxane, methylphenylsiloxane, diphenylsiloxane or Methyl-fluoroalkalysiloxane units or mixtures of at least two such units be. The methyl fluoroalkylsiloxane units which may be present preferably contain g3 up to 10 carbon atoms per fluoroalkyl radical. An example of such a fluoroalkyl group is the 3,3,3-trifluoropropylres. Also methyl tetrafluoroethyloxyalkylsiloxane units can be present in these plasticizers.

Contain those used according to the invention which can be crosslinked to form elastomers Mass of plasticizer, preferably in inclines of 10 to 80 percent by weight, based on the total amount of plasticizer, crosslinkable diorganopolysiloxane and in; Presence of this copolymer produced by this diorganopolysiloxane.

The higher the proportion of diorganopolysiloxanes end-blocked by triorganosiloxy groups on the total weight of the compositions used according to the invention, the higher it is Extent of the deviation from the vegetation.

Before applying the compositions used according to the invention, the Concrete surfaces to be protected from growth are primed, e.g. in the one above mentioned US 41 33 938 described.

The application of the compositions used according to the invention to the pre-vegetation The surface to be protected can e.g. by brushing, pouring, spraying or rolling on take place. Solvents such as toluene can be used in this application.

In the following examples, all data refer to parts and percentages by weight unless otherwise specified.

Example 1 a) After emptying a river water channel with a concrete wall is at a right angle to the direction of the current to two 1.5 m wide in the case of a sloping concrete wall Strip a primer sprayed on, which can be obtained by adding a mixture of 13 Parts of methacryloxypropyltrimethyloxysilane, 48 parts of ethyl methacrylate and 1.2 parts Di-tert-butyl peroxide to 122 parts of toluene within 6 hours with simultaneous Heat to reflux and further heat to boil for one hour was prepared under reflux after the addition of this mixture was complete.

b) After this primer coat dries, it becomes an elastomer crosslinkable compound based on diorganopolysiloxane on the primed strips in a 1 mm thick layer, which was produced as follows: In one Polymerization vessel with an inner diameter of 312 mm and a height of 600 mm, the anchor stirrer operated with a width of 200 revolutions per minute of 295 mm at the widest point, gas inlet pipe and reflux condenser is, a mixture of 5.2 kg (50 mol) of styrene, 4.2 kg (33 mol) of n-butyl acrylate, 4.04 kg in the terminal units each with a Si-bonded hydroxyl group containing dimethylpolysiloxane with a viscosity of 430 mPa.s at 250C, 0.8 kg of water and 0.141 kg of 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane means a steam jacket kept at 100 ° C. for 7 hours.

To remove unreacted monomers and water initially blown nitrogen through the reaction mixture at 1000C to 1300C and then the reaction mixture for 3 hours ; 16 mbar (abs.) To 1300C warmed up. The dioranopolysiloxane obtained in this way, the rod-shaped copolymer from {; rol and n-butyl acrylate, which by Mischpolymerisaion the said Monomers was generated by means of free radicals in counterpart of the diorganopolysiloxane, has a viscosity of 45,000 mPa s at 250C and a gross composition of 30% Dimethylpolysiloxane, 31.5% derived from n-butyl acrylate conductive units and 38.5% % units derived from styrene. 4It is applied to the primed strips, after it with 8%, based on its weight, methyltris- (sec-butyl-) minosilane was mixed as a crosslinking agent, creating an oge; -Eantes one-component system was obtained.

he from the mass, the production of which has been described above, The generated coating is in the air within 24 hours of exposure containing water vapor crosslinked. Shaped body, .ie made from the same mass have the following egg properties: hore-A hardness, tensile strength, tear strength. Elongation at break tIN 53 505 DIN 53 504 ASTN D 624 B DIN 53 504 N / mm2 N / mm 83 7 50 180 he coatings on the canal wall leave even after 7 years in which water flows through the canal, see no vegetation, while on the neighboring, untreated concrete surfaces, a thick growth of algae has formed, which means a brush is very difficult to remove.

Example 2 a) On concrete blocks with the dimensions 40cm x 40cm x 6cm with rough and smooth surfaces is primer, its preparation in example 1 under a) was described, sprayed on.

b) After the primer coat dries, one becomes an elastomer crosslinkable compound based on diorganopolysiloxane on the primed concrete blocks sprayed on by mixing 65 parts of the rod-shaped copolymer from styrene and n-butyl acrylate containing dimethylpolysiloxane, its production in Example 1 under b) was described, with 35 parts of alkane mixture with a boiling range from 80 to 110 ° C at 1013 mbar (abs.) and 1 part of pyrogenic silicon dioxide with a BET surface area of 200 m2 / g and mixing shortly before application with 3 parts of a mixture of 1 part of the silicon-tin compound of the formula Si [O Sn (C4H) gOOC 0M3J4 and 3 parts of tetra-n-propylsilicate, so a represents so-called two-component system.

The thickness of the elastomer layer is approximately 0.6 to 0.8 mm.

The mechanical properties of this layer are about the same, as given in Example 1 for moldings.

Over the coated stones will be a year in the river water channel Run water. After that, about 50% of the surface is the coatings free from vegetation and 50% of them Surface covered with green algae, which can be easily removed with a jet of water, while the untreated Slanted concrete wall on which the treated stones were stored, thick with algae and other aquatic plants.

Example 3 The procedure described in Example 2 is repeated with the modification that the composition is described in Example 2 under b) , additionally with dimethylpolysiloxane end-blocked by trimethylsiloxy groups with a viscosity of 350 mPa s at 250C in an amount of about 15% on the total weight of this oil and the dimethylpolysiloxane with ischpolymerisat, was mixed. After the year in the river water channel, the coatings are complete free from vegetation.

only the surface of the yacht below the waterline is covered with a thin layer that can be easily wiped off with a cloth can.

Claims (3)

Patent claims process to prevent fouling on concrete surfaces, that have been under water containing living beings for so long that there are Surfaces can form fouling, whereby on the surface to be protected from fouling a coating made of a compound which can be crosslinked to form an elastomer and is based on Diorganopolysiloxane is applied and allowed to crosslink, d u r c h g e k It is noted that the diorganopolysiloxane in the crosslinkable mass is such is, the rod-shaped copolymer of styrene and n-butyl acrylate contains, by interpolymerization of the monomers mentioned by means of free radicals in Presence of the diorganopolysiloxane was generated. 2i method according to claim 1,. d a d u r c h e k e n n -z e i c Not that the rod-shaped copolymer is 45 to 75 percent by weight from units derived from styrene and the remainder from n-butyl acrylate dissipative units. 3. The method according to claim 1 or 2, d a d u r c h g e -k e n n z It should be noted that the amount of the diorganopolysiloxane is 20 to 60 percent by weight, based on the total weight of diorganopolysiloxane and mixed polymer of styrene and n-butyl acrylate. F. The method according to at least one of claims 1 to 3, d a d u r c h g e k e n n n n z e i c h n e t that the compound that can be crosslinked to form elastomers is additionally to crosslinkable diorganopolysiloxane and in the presence of this diorganopolysiloxane generated Copolymer of styrene and n-butyl acrylate as well as crosslinking agents and optionally Crosslinking catalyst diorganopolysiloxane end-blocked by triorganosiloxy groups in amounts of 10 to 80 percent by weight, based on the total weight of through Triorganosiloxy end-blocked organopolysiloxane, crosslinkable diorganopolysiloxane and in the presence of this diorganopolysiloxane produced copolymer.