DE2218973A1 - Process for the production of compound products - Google Patents

Description

Patent attorney Dipl.-Ing. Werner Gramm

Societa Italiana per Azioni. 33 Braunschweig, March 20, 1972

per la Produzione di OaIci · Theodor-Heuss-Strasse 1 ■

e Cementi di Segni. Phone: 0531-80079

Rome, Italy

31, Via Lombardia

"Method of Preparing Attorney's File 3314- Pt

of compound products "

The invention relates to a method for producing Compound products based on hydraulic cement and resin, the special physical-mechanical and application technology Have characteristics, as well as the products made with this process.

Although cement mix binders are excellent for various applications Represent building materials, they are not usable in some cases due to their inherent property, especially if the system is to withstand particular loads.

The technique of soaking these cement mixers with substances subsequently polymerized in place is has been greatly improved in recent years, and due to the remarkable increase in density and chemical and mechanical strength, which can be achieved by impregnating with resin, are the possible applications these products have become more numerous.

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Through experiments with to be used as impregnation substances Monomers, methyl methacrylate (MMA) was identified as an impregnating agent, creating compound products based on hydraulic cement and resin with exceptional characteristics can be obtained.

The extension of this technique of impregnation with resin to cement products, characterized by a high structural Microporosity, as for example in the method according to the German patent application P 21 39 208.5 from August 5, 1971 by the same applicant has the special and unique suitability of methyl methacrylate for impregnation of these products.

The use of carriers with the above properties in the manufacture of compound products has - accordingly the nature and composition of the cement mixers used - in addition to the special ones in the manufacture of these products under prevailing conditions that it is possible to determine the formation of special "skeletal" structures, which are not only mechanically resistant, but also as actual in the subsequent impregnation phase Molecular sieves act with regard to the impregnation system.

This reduces the number of catalysts to be used, which are suitable for on-site polymerization of the impregnation monomer. Therefore only such come

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Catalysts in question whose molecular size is compatible with the microporosity characteristics of the carrier.

Taking these results into account, the Tests Catalysts are used that have a linear and acyclic molecular structure, such as diisopropyl peroxocarbonate, Dilauroyl peroxide, tertbutyl perpivalate, sodium and potassium persulphate as well as "the linear and acyclic Azo polymerization catalysts.

Extensive tests have shown that the best results have been achieved with the azo catalysts.

Thus the process of making compound products exists according to the invention essentially in the tear ■ cement products, especially those with a high structural microporosity, with methyl methacrylate, in which in liquid form a polymerization azo catalyst linear and acyclic structure is present, as well as in the subsequent polymerization in place of the methyl methacrylate s in the soaked products.

The azo catalysts and in particular the azo-bis-isobutyronitrile (AIBN) have some advantages over the other catalysts, especially from a technological point of view are of great interest.

In contrast to the peroxides, the azo compounds guarantee and in particular the AIBN a sufficiently rapid impregnation of the products by using only the capillarity

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with satisfactory results in terms of the achievable degree of impregnation and the complete absence of general disadvantages, which occur entirely during the impregnation phases and which are due to the particular instability of the usual monomer catalytic accelerator systems are due.

It was found that products included in an AIBN as Catalyst-containing MMA bath were immersed, a larger one by simple capillarity with the same soaking time The amount of monomer absorbed, resulting in maximum density and mechanical strength of the subsequent polymerization Compound products could be achieved.

The better impregnation of the product is closely related with the particular chemical stability of the MMA / AIBN system, which is its initial during the entire operating time Maintains viscosity, namely remains liquid, while the other systems containing peroxides or persulphates In contrast, they often tend to prepolymerize with a corresponding increase in the viscosity of the impregnating agent and the resulting weaker penetration into the product.

Due to the stability of the MMA / AIBN bath, it is dated technical From the point of view it is possible to use one and the same impregnation bath several times, which results in savings Monomers and catalysts compared to the baths containing other catalysts, which gradually become more viscous will.

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The "remarkable stability and the lack of any Pre-polymerization phenomena in the MMA / AIBN bath can occur can be improved 'if to accelerate the impregnation process working under pressure. Experience has shown that all catalysts except the azo compounds tended to cause the monomer to polymerize even during the impregnation phase. Through this there is practically a partial penetration that is more non-homogeneous Type of monomer in the product; sometimes · becomes thereby but also causes the formation of a resin layer of different thickness on the outside of the product.

In addition to the advantages just explained when using polymerization azo catalysts and in particular AIBN, the subsequent phase of polymerization of the bound monomer is also easier, for example by simply immersing the soaked product in a thermally stabilized water bath at one temperature of about ^{70-80 0} O (compare the German patent application P 22 03 146.5 of January 24, 1972 by the same applicant), without the need for a gradual heating of the bath - as in other cases - in order to reduce the degree of impregnation due to the outflow of the bound Avoid monomers.

Other suitable ones to be used in the method of the invention Polymerization azo catalysts are for example: Alpha, Alpha'-Azο-Bis (Alpha, Gammadimethylvaleronitril, Dimethyl- and diethyl-alpha, alpha'-azo-diisobutyrate, alpha, Alpha'-azo-bis (alpha-ethylbutyronitrile) and alpha, alpha'-azo-

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Diisobutyrocarbonamide. The amount of azo catalysts can vary within wide limits, but an amount between 0.5 and 4.0 % of the MMA amount is preferably used.

The invention is explained in more detail using the following examples:

example 1

Mortar products from a mixture in the ratio of 70 Parts by weight of Portland cement with a high silicon content (3.10) and a low additional content (1.30) and 30 parts by weight of sand with a high SiOp content and according to Italian Norms standardized sand in a ratio of 1: 3 with a water: cement ratio of 0.40 were subjected to the following aging conditions subject to:

a) pre-aging for 12 hours at room temperature;

b) 3 hours treatment in an autoclave at 215 ° 0 (20 atm);

c) 4 hours of thermal treatment under atmospheric pressure at a temperature of 200 C.

After this treatment, these products showed a pressure

2
strength of 1,520 kg / cm.

Some of the products were soaked in methyl methacrylate with a 2% addition of benzoyl peroxide, while the other products were impregnated with the same monomer, but with azo-bis-isobutyronitrile (2%) as a catalyst contained.

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η _

Before and after the on-site polymerization, the following impregnation and compressive strength values were measured:

1. Products immersed in an MMA bath containing 2% benzoyl peroxide

% bound monomer 7 %

Compressive strength 1,600 kg / cm

2. Products immersed in an MMA bath containing 2% AIBN

% bound monomer 7 »5 ° / °

Compressive strength 2,920 kg / cm '

Confirming the various values required for the mechanical Strength were measured, the test according to point 1 shows that the products in spite of a complete impregnation are polymerized with the monomer only at their edge zones.

he ■.

The chemical investigation / brought a gradual decrease of the benzoyl peroxide in the impregnation mixture of the outer to inner layers, which the catalyst practically did not reach at all.

In the test products using AIBN as a catalyst a uniform distribution of the polymer within the product was determined, which indicates a complete and can close homogeneous penetration with the impregnation system.

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Example 2

Mortar products produced according to Example 1 were subjected to soaking under pressure (16 hours at 30 atm), part of the products being immersed in an MMA bath with 2% dilauroyl peroxide as catalyst, the other part in an MMA bath, the 2% AIBN had been added as a catalyst.

After the treatment it turned out that the dilauroyl peroxide containing bath was partially polymerized, which was once read from the increased viscosity of the bath itself (unusable for further use), but on the other hand on the resinous layer that is on the surface of the Products had formed. The viscosity and the depth of penetration into the product of the bath containing AIBN remained but unchanged, so that the bath could be used immediately for further impregnation processes.

Before and after the on-site polymerization, the following impregnation and compressive strength values were measured:

1. Immersed in an MMA bath containing 2% dilauroyl peroxide Products: -

% bound monomer 2.2%

Compressive strength 2,000 kg / cm

2. Products immersed in an MMA bath containing 2% AIBN

% bound monomer 8.1 %

ο Compressive strength 3.180 kg / cm

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Example 5

Products manufactured according to Example 1 during their manufacture however, instead of the standard sand, a basalt sand corresponding to the aging conditions listed above is used had a compressive strength of 1,380 kg / cm.

Some of these products were immersed in an MMA bath containing 2% benzoyl peroxide, while the remaining products were immersed in the same monomer bath with the addition of 2 % dilauroyl peroxide.

Before and after the on-site polymerization, the following impregnation and compressive strength values were achieved:

1. Products immersed in an MMA bath containing 2% benzoyl peroxide

% bound monomer 7 ° / °

ο Compressive strength 1,400 kg / cm

2. Products immersed in an MMA bath containing 2% lauroyl peroxide

% bound monomer 8.6%

Compressive strength x 2,500 kg / cm ²

After the end of this treatment, the results were consistent With regard to the degree of impregnation of the products, those determined in connection with Example 1.

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Example 4

Mortar products produced according to Example 1 which have the under Example 1 were subjected to aging conditions explained, were immersed in the following monomer-catalyst systems:

1. MMA plus 2 % benzoyl peroxide

2. MMA plus 2 % AIBN

3. MMA plus 2 % dilauroyl peroxide

Before and after the on-site polymerization, the following values were achieved:

1. % bound monomer 7 * 1 ° / ° compressive strength 1,580 kg / cm

2.% bound monomer 7 »^ ° / ° Compressive strength 2,750 kg / cm ²

3. % bound monomer 7> 8%

ο Compressive strength 2,400 kg / cm

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Claims (3)

Claims 1. Process for the production of compound products, characterized in that cement products with an Az o catalyst in dissolved form containing methyl methacrylate soaked and then conditions under • be thrown, under which the polymerization in place and Place of the monomer takes place. 2. The method according to claim 1, characterized in that the polymerization catalyst is azo-bis-isobutyronitrile is used. 3. The method according to claim 1, characterized in that the raw cement products have a high structural microporosity. Pat en; Ing. Werner Gramm
attorney 209 8 46 MCH 6 .. ORIGINAL INSPECTED