CS210568B1 - Chemically resistant product and method of its production - Google Patents

Abstract

The invention enables the economical production of building structural elements and parts that are to be exposed to both mechanical and chemical stress, based on macromolecular materials. According to the invention, it is possible to produce elements from a polycondensation, acid-cured binder and granular fillers in a weight ratio of less than T : 10, if a microfiber material is used as a hardener carrier. The significantly larger specific surface area of the microfibers (compared to an internal granular carrier) allows polycondensation to start from a large number of centers simultaneously; this also results in a denser crosslinking of the macromolecular matrix and, in addition, the microfibers effectively reinforce the macromolecular chains and thus improve the resulting mechanical properties. Furfuryl alcohol, furfuryl alcohol precondensate or precondensate modified with epoxy resin can be advantageously used for the binder, and high-frequency vibrations can be advantageously used for production.

Description

The invention relates to a chemically resistant article made from a mixture of fillers, polycondensation binders and additives, and to a process for its manufacture.

The components and products to be subjected to chemical stress have so far been produced both from traditional ceramic materials and from various types of plastics. Of the synthetic resins, the furan resins, either alone or in various modifications, are used for particularly difficult conditions; phenolic epoxy, polyester and other resins are also used for special purposes. Due to some disadvantageous properties of the pure resin products, resin-filled materials or various organic and inorganic fillers bonded with resins, such as plastics and plastics, are generally more widely used.

In order to advantageously use plastics and plastmalt with a furan or other polycondensate, acid-cured binder for construction purposes, that is to say the product material is sufficiently strong and yet impermeable, the binder to filler ratio has to be maintained above 1:10, the high binder content it was necessary to maintain the optimum granulometric composition of the filler and the perfect processing of the mixture ejection. The main reason for the necessity of a large proportion of binder was the hitherto: methods of adding hardeners. When adding the hardeners in the liquid state, a certain amount of water or diluent was always introduced into the mixture, which generally reduced the number of active centers at which polycondensation began. The presence of water in the mixture has also been a cause of the jury ^\: Tosti, the hardened mass, which reduced the overall density of the material of the product, and moreover, it was very inconvenient that pores were continuous. When the hardener was introduced on an internal powder carrier, for example on quartz sand, or when the hardener was added in the form of salts of the respective acids, the adverse effect of the diluent or water did not occur, but the specific number of active cores was further reduced. considerable doses of the curing accelerator into the mixture, these doses being up to 2 wt. parts of accelerator for 10 wt. binder parts. Despite these measures, curing took a long time and was imperfect without energy supply, especially heat. The addition of the curing accelerator has always led to a deterioration in the resulting properties of the finished product. In addition, the internal carriers used deteriorated the processability of the fresh composition without guaranteeing sufficient thixotropic properties. In addition, the materials produced in this way were characterized by low tensile strength compared to compressive strength, which limited their structural applicability. It was still necessary to add special microfillers to the mixture to reduce porosity and impermeability, which on the other hand inefficiently bound large amounts of fillers.

The drawbacks of the prior art chemically resistant articles are largely overcome by the article of the invention, made of polycondensic acid cured binder, granulated fillers and additives, which is characterized in that it contains a plurality of polymers.

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An after-curing, acid-cured binder which is less than 1: 10 in proportion to the amount of granulated filler, and contains an additive of microfibrous material that is an acid curing carrier. In another aspect of the invention, the binder is a furyl alcohol resin, optionally mixed with furyl alcohol.

According to a preferred embodiment of the invention, the polycondensation binder is modified by the addition of 10 to 65% epoxy resin. The chemically resistant article of the invention may contain 0.7 to 3.0 wt. parts of furylaldehyde or butylaldehyde.

According to a further preferred embodiment of the product according to the invention, the microfibrous material carries on its surface 1.0 to 8.0 wt. an acidic hardener, wherein the microfibrous material is preferably microfibrous asbestos.

The present invention also provides an advantageous method for producing a chemically resistant article, wherein the mixture of polycondensation binder, granular filler and microfibrous material bearing an acidic hardener is molded and processed by vibration, in particular high frequency vibration at a frequency of 12,000-14,000 c. / min. and by acting at a pressure of 0.2 to 3.0 MPa and a temperature of 35 to 60 ° C. In the same way, a mixture applied for chemical protection to the surface of a product or component made of another material, such as concrete, is processed.

With the chemically resistant article of the present invention, a substantial reduction in the amount of binder and cure accelerator required is achieved, the fresh composition for the manufacture of these articles having improved processability and the composition having better thixotropic properties. The processed mixture hardens more quickly and the total cure time of the mixture is reduced while improving the homogeneity of the cured material. For products, an increase in the relative unit tensile strength of the material is achieved, which is due to the use of an additive of microfibrous material, in particular asbestos, which, in addition to the function of micro-filler, assumes a very advantageous "

the function of the acid hardener carrier.

The summary of these advantages and excellent material properties of the chemically resistant article of the invention is based on the addition of a microfibrous additive since the specific surface area of suitable microfibers is considerably larger than other inert hardener carriers and allows polycondensation to start at the same number or less . This also leads to more dense cross-linking of macromolecules! and improved sorbent dispersion of the polycondensation water.

The dynamic contact stress of the microfibers with the liquid monomeric binder is lower with respect to the surface properties of the fibers than with the previously used microfillers; this improves on the one hand the processability, on the other hand the thixotropy of the fresh mixture.

The transverse dimension of the microfibers is only one order larger than the size of the macromolecules. This allows for improved reinforcement of matrices, macromolecular chains, and an increase in the values of the mechanical characteristics of the cured material, in particular the tensile strength.

From a physical point of view, the microfibre resin acts as a hardener carrier as a homogeneous binder of the granular filler system. This, along with other reasons, is the cause

210,368 overall less binder needed and less power required to achieve highly durable, impermeable and solid products.

A further improvement in the properties of the products is achieved by the addition of a suitable silane or titanium agent, which results from the formation of cohesive bonds between the resin binder and the filler or microfibrous material.

The preparation of the chemically resistant article of the invention is illustrated by the following examples.

Example

When preparing the product according to the invention, 120 wt. 60 parts by weight of silica filler. parts of sand with a grain size of 12 to 15 mm, 25 wt. parts of sand having a grain size of 2 to 4 mm and 15 wt. parts of sand with a grain size of 0.2 to 0.5 mm. The filler is mixed with a pre-mixed binder consisting of 10 wt. parts by weight of furfuryl alcohol based, 15 wt. parts by weight of a mixture of microfibrous asbestos and urea nitrate in a ratio of 12: 3, based on parts by weight, and from 0.7 parts by weight; parts of furfuryl aldehyde.

After thorough mixing, the mixture is filled with the desired component, such as a segment, shaped piece, oven, etc., having a minimum wall thickness of 40 mm, whereupon the mixture is subjected to vibration, preferably high frequency vibration of about 14,000 c / min. 2 to 1.0 MPa and allowed to cure for 1 to 3 hours at 35 to 40 ° C.

However, not only separate articles need be made from the composition, but the composition can also be applied to other articles and processed in an appropriate manner to form a chemically resistant protective sheath of other articles.

Example 2

First, 140 wt. parts by weight of a granular filler having a grain size of 4 to 7 mm; parts of unexpanded perlite having a grain size of 0.5 to 1 mm and 12 wt. parts of rubber dust with grain size 0 to 0, 125mm. The filler is then mixed with a pre-mixed binder consisting of 10 wt. parts of furfuryl alcohol, from 9 wt. parts by weight of a mixture of polypropylene microfibres 8 with urea nitrate in a ratio of 6: 3, taken in parts by weight, and of 2 wt. parts of butyraldehyde.

After thoroughly mixing and filling the molds, the mixture is compressed at a pressure of 2 to 5 MPa at a temperature of 60 ° C, the compression die having a mesh with small openings to allow gas escape during compression and polycondensation. The die may also be profiled to form a relief on the back of the article to improve consistency with the adjacent article or adjacent layer of other material.

Claims (7)

A chemically resistant product formed from a mixture of polycondensation, acid cured binders, granular fillers and additives, characterized in that the weight ratio of polycondensation, acid cured binders and granular fillers is less than 1:10 and the additive consists of a microfibrous material which is a carrier of an acidic hardener of a polycondensation binder. 2. A chemical resistant article according to claim 1, wherein the binder is a furan resin based on furfuryl alcohol or a mixture of furfuryl alcohol resin and furfuryl alcohol. 3. The chemical resistant article of claim 1, wherein the polycondensation binder is modified by the addition of a 10 to 65 epoxy resin. 4. The chemical resistant article of claim 1 wherein the starting mixture comprises an additive of 0.7 and 3.0 wt. parts of furfuryl aldehyde or butyraldehyde. 5. The chemical resistant article of claims 1 and 2, wherein the microfibrous material is microfibrous asbestos. 6. A chemical resistant article according to claim 1 or 5, wherein the microfibrous material is supported on its surface by 1 to 8% by weight. acid hardener. 7. A method of producing a chemically resistant article according to claims 1 and 6, characterized in that the mixture of the polycondensation binder of the granular filler and the microfibrous material previously mixed with the acidic hardener of the polycondensation binder is filled or molded onto the protected side of the article. with a vibration, in particular a high frequency of 12,000 to 14,000 c / min, and a joint pressure of 0.2 to 0.3 MPa and a temperature of 35 to 60 ° C.