DD221461A1 - PROCESS FOR BINDER PRODUCTION FOR THE MODIFICATION OF COATINGS - Google Patents

Abstract

The invention relates to a process for the preparation of a binder for modifying bitumen, tar and pitch mixtures with or without other additives by copolymerization of dienes with vinylidenecarboxylic acid, 56 to 60% styrene and / or ring-substituted styrenes in the presence of a maximum of 0.5%. emulsifier. Polymerization is carried out in 3 temperature steps up to a nearly complete conversion and an average particle size of more than 2 000 Angstroem. Such binders are particularly suitable for coating compositions on metals in combination with products resulting from the coking of brown coal to BHT coke. Better resistance to settling, better adhesion to iron or steel and higher film strength is achieved.

Description

Title of the invention

Binder manufacturing process for the modification of coating compositions

Fields of application of the invention

The invention relates to a process for the manufacture of binders for the modification of coating compositions based on a carboxylated copolymer latex. By the method of preparation according to the invention an improved intermolecular interaction between this binder and bitumen, tar or pitch or their mixtures is effected.

Characteristic of the "known technical solutions

The use of carboxyl group-containing elastomers in coating compositions based on aqueous polymer dispersions for the corrosion protection of metals is known and is described, inter alia, in German Patent Specification No. 202 297. However, it has been known for several years that blasting of concrete elements is not the first priority Leaching, base exchange, Auskristalisieren or blooming is caused, but by undercutting.

Corrosion is the inadvertent destruction of materials. Sometimes the failure of one material may cause the destruction of another, even though this material alone would not have corroded. This can be z. B. happen on concrete elements with metal reinforcement. The rusting of the metal within the concrete elements leads to the demolition of the concrete and ultimately to a gradual complete destruction of the element. In particular with concrete elements, which are used in the housing sector, this results in large economic losses and dangerous moments.

The corrosion behavior of the reinforcement is determined not only by the position of the tie used in the electrochemical series, but also by the presence of foreign substances or admixtures in the metals and by the composition of the building material. Since the corrosion of high polymer materials due to their high chemical resistance is relatively insignificant, it is obvious that this property u. a. also used for the corrosion protection of metals.

According to Brockhaus ABC Chemistry, Volume 1 A -K, TEB E, A. Brockhausverlag Leipzig, 1971, page 724, corrosion protection by coatings as a separating layer between metal and corrosive agent is the most common. The problem here is always the nature of the surface of the metal, the principle requires a careful surface preparation -voraussetzt. However, z. B. by welds on the metal surface to be treated, a different adhesion or adhesion of the molecules occur at the interfaces.

DD-PS 129 662 describes coating compositions of combinations of synthetic xatices with functional groups and customary known starting materials. The usual agents used, such as inorganic pigments, plasticizers, etc., usually react destabilizing to temperature increases or cause a phase separation by a slow increase in salt concentration. The corrosion protection coatings according to DD-PS 129 662 and 146 613 with their essential advantages and disadvantages, but are only suitable for corrosion protection of metal surfaces that are not enclosed, such. B. of metal reinforcements in concrete elements, but z. B. for car underbody protection.

The destruction of components with metal reinforcements, such. B. braids or fabrics or Baublechen is counteracted by Schutzübersüge; one speaks of protective procedures. Such protective coatings usually consist of tar or pitch. To improve the adhesion, the solvents originally used are increasingly being replaced by aqueous emulsions, since in addition to the economic advantages, environmental pollution is also reduced. Furthermore, a significant advantage is that aqueous dispersions or emulsions are applied to wet substrates

can "what is not possible with solvent-based products".

For Schutziiberzüge a distinction depending on the feed different tars, such. B. Coal, lignite, wood, bone and fat tar "On an international scale, only hard coal or oil or lignite coal tar are used. During production, several compounds are formed, some of which are still contained in the tar. For example, coal tar contains predominantly aromatic compounds and brown coal tar predominantly aliphatic hydrocarbons.

For several reasons binders based on high polymers are added to the protective compositions. This will u. a. improves the adhesion, but also enhances the film texture by impermeability. For stability reasons, a compatibility of all components is necessary, since otherwise the unstable materials precipitate quickly and / or also form uneven protective films. Normal aqueous emulsion Polyraerisate are therefore not suitable because the adhesion is insufficient, the high Emuig at or halt the water resistance negatively affected and no resistance to the compounds contained in the tar is given.

The great importance of brown coal coking according to the brown coal high temperature method (BHT) for our economy automatically means that the supply of BHT tar and pitch will increase. The latter, however, contain compounds which have a corrosive effect on metals and also destabilizing known binders. In particular, phenols and creosote are here nenen, and nitrogen compounds in farm pyridine bases and sulfur-containing body, especially Thiophenhomologe.

Object of the invention

The aim of the invention is to produce a binder which in combination with mixtures of bitumen, tar or pitch, in particular those from the BHT coking, with or without other additives for coating compositions with improved properties with respect to heel formation, adhesion to iron and / or steel and increased pitting resistance.

Explanation of the essence of the invention

The invention has for its object to develop a manufacturing method for a binder for modifying coating compositions, which meets the above requirements.

The object is achieved in that dienes having 4 to 8 carbon atoms, for. B. 1,3-butadiene, with conjugated ethylenically unsaturated carboxylic acids and 56 to 60 <fo styrene or ring-substituted styrenes in the presence of at most 0.5 $ emulsifier in aqueous emulsion in 3 temperature stages are polymerized as follows:

$ 20 > of the monomers are at temperatures

below 65 ° C,

70 "ρ of the monomers between 65 and 80 ⁰ C and the rest of the monomers above 80 ⁰ C almost completely

implemented such that a latex having an average particle size of greater than 2,000 angstroms is formed.

As conjugated dienes, those having 4 to 8 carbon atoms, in particular a diene having 4 to 6 carbon atoms, are used

preferably butadiene-1,3 used. If it has an alkyl substituent, the alkyl group contains 1 to 2 carbon atoms. Preferred examples of suitable alkyl-substituted butadienes are isoprene, piperylene and 2,3-dimethylbutadiene-1,3, with isoprene being preferred.

The ethylenically unsaturated carboxylic acid compounds which can be used according to the invention include: acrylic acid, methacrylic acid, crotonic acid, itaconic acid and fumaric acid.

According to the invention, it is possible to use known anionogenic emulsifiers, such as alkylasylsulfonates, sulfated esters of fatty acids, sodium lauryl sulfate, individually or in a mixture. Such emulsifiers are also well-tolerated with nonionic emulsifiers such as Alkylphenolpolyäthoxyläthanolen or other polyglycol ethers, which arise in the reaction of 3 to 30 moles of ethylene oxide with fatty alcohols having 10 to 20 carbon atoms and are often included as dispersants in pigments or other dispersions and so get into a coating mass.

Suitable polymerization initiators are the customary polymerization catalysts for emulsion polymerizations, in particular water-soluble peroxidic catalysts such as ammonium persulfate, potassium, sodium persulfate and hydrogen peroxide. In addition, water-soluble azo

w. decompose to form radicals compounds hiss in aqueous solution at temperatures of 50 and 100 ⁰ C, such as azodiisobutyronitrile and -diisobuttersäurediamidjeingesetzt. Mixtures of catalysts of the type mentioned and mixtures of catalysts of the type mentioned with non-water-soluble catalysts such as benzene peroxide or cumene hydroperoxide are possible.

Further, it should be noted that only sulfur-free regulators are suitable when using regulators Sulfur appears to have a negative influence on the adhesion of the coating composition to metals, and this is also due to one of the causes of the property improvements of the inventive carboxyl group-containing polymers, since there is no sulfur for their crosslinking is necessary, as with usual Butadien / Styrenlatices without functional groups.

The invention will be explained below by way of examples. The stated parts and percentages are by weight, example 1 being according to the invention and example 2 indicating the state of the art.

Exemplary embodiments Example 1

In a stirred autoclave, 552 parts of distillate, 8 parts of potassium persulfate, 2.1 parts of sodium benzene sulfonate, 4.5 parts of a mixture of pumaric and acrylic acid, 5 parts of sodium bicarbonate, 6 cTl. Carbon tetrachloride, 59 parts of styrene and 39 parts of butadiene, reacting for 3 hours under 65 ^° C., then about 380 parts of a mixture consisting of 293 parts of styrene and 210 parts of butadiene are reacted between 65 and 80 ^° C. after which the remaining amount of the mixture at a temperature of about 80 ⁰ G up to nearly 100 i <> - owned sales of all monomers will react. At the end of the reaction, the pH is adjusted to 7.5.

Example 2

Following an ordinary emulsion polymerization addition procedure, an earboxylated latex was made using the same amounts of raw materials as used in Example 1, according to the current state of the art.

Example 3

For further comparison, a commercial rubber latex with about 51 # styrene and $ 49 > butadiene was used

Table 1 shows some physical characteristics. Table 1:

in io 1 example 2 3 in Ang 50.8 50.4 51.2 Total solids 0 particle size (Dyne / cm) 2180 1640 800 Strom 45 55 40 OberfI.spannung (N / mm ² ): 7.5 7.5 10.5 PH value 20 ⁰ G Pilmfestigk. in 120 ⁰ C 6.5 6.5 4.5 after 24 hours at 13.0 11.5 7.5 after 10 min. at

Example 4 to

Twenty Tl of latex of Examples 1 to 3 were mixed with a BHT-Teerdispersion consisting of 55 parts of a 6 #igen alkaline casein solution and 45 Tl. BHT tar.

In Table 2, the values for the formation of sediment according to Wassmuth-Boiles are given, whereby the force is measured in g, which is necessary to push a cone with certain dimensions through the sedimented layer to the ground. 10g mean a still very easy to touch sediment, 300 g a hard, no longer touchable sediment.

Table 2;

Examples Sediment in g after 1 3 6 14 30 60 90 days 1 2 3 ' 10 10 10 10 10 20 10 30 50 10 80 100 10 200 300 20,300 180

Further, 25 g of the mixtures of Examples 4 to 6 were placed on an iron plate of 50 x 100 mm, placed on a same plate and dried under the same slight pressure of 0.1 U / mm ^{2 for} 2 hours at 70 ⁰ C.

Table 3 shows the force required to separate the 2 iron plates. It thus gives a comparison to the metal adhesion of the various mixtures. '·

Table 3:

Examples 1 2 3 applied force (Ii / mm2) 1.8 0.7 0.15

Claims (1)

Invention claim Binders for the modification of coating compositions of bitumen, tar or pitch or their mixtures by copolymerization of conjugated dienes having 4 to 6 carbon atoms, 56 to 60 $ styrene or ring-substituted styrene and ethylenically unsaturated carboxylic acids in the presence of at most 0.5 f ° Emulsifier in aqueous emulsion, characterized in that the polymerization is carried out in 3 temperature stages such that 20 io of the monomers below 65 ⁰ G, 70 ^c ß> between 65 and 80 ⁰ C and the rest of the monomers above 80 ⁰ G up to a nearly complete conversion to a latex having an average particle size of over 2,000 angstroms.