DD296267A5 - METHOD FOR PRODUCING POLYMOMODIFIED CEMENT-CONTAINING COMPOUNDS - Google Patents

Abstract

The invention relates to a process for the preparation of polymer-modified cementitious composites which are widely applicable in the construction industry. The object of the invention to provide a method for producing polymer-modified cementitious composites having improved mechanical and chemical properties is achieved according to the invention by providing a 3 to 6% solution of a copolymer of methyl methacrylate and 3 to 6% aqueous solution of the starting material of the cementitious composite Methacrylic acid is added with a minimum content of the acid component of 25%. {Composite; Cement; methacrylate; copolymer; construction industry; copolymer}

Description

embodiments

example 1

60 g of methacrylic acid, 140 g of methyl methacrylate and 200 mg of azoisobutyrodinitrile are polymerized as an indicator under reflux and inert gas for 15 hours in 1600 ml of acetone in a provided with stirrer, reflux condenser, thermometer and N _{2 introduction} sulfonation. After cooling the reaction mixture, the copolymer is precipitated with stirring in hexane and the copolymer is then dissolved in a aqueous-ammoniacal medium. The viscosity can be adjusted as desired depending on the polymer concentration.

Polymer content [%] Viscosity [mPa]

6.0 34

7.0 57

8.0 120

These aqueous ammoniacal polymer solutions called polymer content serve as a base material for the production of a composite of a hydraulic cement in the presence or absence of glass fibers.

Example 1 a

2.5 kg of Portland cement are thoroughly mixed with 1 kg of water. In an analogous example 2.35 kg Portland cement with 1 kg of the above aqueous ammoniacal polymer solution (pH 9.2), the polymer content was 6.0 parts by mass in%, also mixed intensively. The molar ratio of the copolymers methacrylic acid methyl ester / methacrylic acid is 66:34. Already visually it can be stated that the polymer-modified cement has better flow properties.

Example 1 b

2.0 kg of Portland cement are mixed intensively with 0.8 kg of water and 60 g of shortened besch-glass fiber silk and processed into shaped bodies of dimension 160 mm χ 40 mm χ 10 mm. In an analogous example, 2.0 kg of Portland cement, 60 g of shortened Ε-coated glass oxide and 0.85 kg of the above aqueous-ammoniacal polymer solution (pH 9.2), whose polymer content is 6.0 parts by mass in%, are also intensively mixed. The molar ratio of the copolymers methyl methacrylate / methacrylic acid is also 66:34.

After 28 days storage of the specimens at room temperature and in a humid atmosphere, the flexural strength of the polymer modified glass fiber cement samples is 13.5 times higher than that of the unmodified glass fiber cement samples.

Example 2

In a 2 liter four-necked flask with stirrer, thermometer, reflux condenser and ^ -Introduction 470g methyl methacrylate, 200g of methacrylic acid, 1 200ml of toluene and 2 g of benzoyl peroxide are added as an indicator and then heated for 5 hours at 80 ⁰ C. The precipitation polymer is then heated at 80 ^° C. for 5 hours. The precipitation polymer is then filtered off with suction and dissolved in aqueous ammonia analogously to Example 1 (pH 9.2).

These aqueous ammoniacal polymer solutions called polymer content serve as a base material for the preparation of polymer-modified glass fiber cement samples. The procedure is analogous to Example 2a and 1b and achieved by the polymer modification a mean improvement in bending tensile strength of 14.2.

Claims (1)

A process for the preparation of polymer-modified cementitious composites, characterized in that the starting components of the cement-containing composite, a mass fraction of at least 30% of a 3- to 6% aqueous ammoniacal solution of a copolymer of methyl methacrylate and methacrylic acid is added with a minimum content of the acid component of 25%. The invention relates to a process for the preparation of polymer-modified cementitious composites, which are widely applicable in the construction industry. The property profile of cementitious composites, such as mortar, concrete, etc., can be adapted to the user conditions by a wide variety of admixtures and additives. Composites with high moduli of elasticity consist mainly of cement-polymer-glass fiber compositions, preferably using hydraulic cement. Such cement-polymer compositions are also used in the manufacture of plastic concrete having improved mechanical and chemical resistance. Thus, in DE 1189435 serving as a building material mixture of cement, aggregates and copolymers of vinyl chloride, vinylidene chloride, acrylonitrile, acrylic acid esters, methacrylic acid esters or Carbonsäurevinylestem and in DE 2837898 a process for producing a composite of water-binding cement, Ε-glass fibers and a Resin dispersion described. Furthermore, it is proposed in DD 71072 to add concrete or mortar mixtures to vinyl acetate homo- or copolymer dispersions. Cement mortar mixtures, to which dispersions of copolymers of hydroxyalkyl (meth) acrylates have been added in order to improve flowability, are also described in US Pat. No. 4,723,360. In all these processes, the polymers are incorporated into the composites as undissolved particles and are contained in them in this form. The achievable improvement in the mechanical and chemical resistance of the composites depends strongly on the particle size of the polymers. Another disadvantage is that only a relatively small interaction between the cement and the polymer matrix is possible, so that the effect on the end product properties is limited. The object of the invention is to provide a process for the preparation of polymer-modified cementitious composites having improved mechanical and chemical properties. The object is achieved in that the starting components of the cement-containing composite, a mass fraction of at least 30% of a 3- to 6% aqueous ammoniacal solution of a copolymer of methyl methacrylate and methacrylic acid is added with a minimum content of the acid component of 25%. The addition according to the invention of these polymer solutions achieves a substantially improved interaction between the copolymer and the other constituents of the composite. The polymer-modified cement-containing composites produced according to the invention are distinguished in particular by a more than 10-fold increase in flexural tensile strength. The methacrylic acid ester / methacrylic acid copolymers are known in the art, e.g. by radical polymerization, in solution, substance or precipitation polymerization or hydrolysis of Polymethacrylsäuremethylestern, produced. The inventive method is particularly suitable for the preparation of polymer-modified cement-containing composites containing hydraulic cement as a basic component and glass fiber as an additive.