LT3519B - Method for reducing allergic effect induced by water-soluble cr(vi) available in cements and /or cement- containing half-finished products - Google Patents

Abstract

The invention relates to a method of reducing the allergy-inducing (allergenic) activity of water-soluble Cr<VI> in cements and/or cement-containing preparations, which comprises selecting in preliminary experiments a lignosulphonate from the multiplicity of lignosulphonates available on the market which reduces, in the desired manner, the water-soluble Cr<VI> content on exposure of a cement and/or a cement-containing preparation to water, and adding this selected lignosulphonate to cements and/or cement-containing preparations prior to or during the addition of water in the production of fresh cement mixtures.

Description

The invention relates to the inhibition of allergenic effects caused by water soluble Cr ^VI in cements and / or cementitious preparations, the prevention of allergic reactions in persons in contact with cements and / or sidings (chromatic eczema).

Water-soluble allergic reactions are known. In addition, Fe (II) sulfate. H ₂ O, quantities may be present.

cement-containing rochromate can cause the known to add effective reduction of Cr ^VI

Iron sulfate (Fe (II) sulfate) in aqueous cement mixtures reduces hexavalent water-soluble chromium (Cr ^VI ) to trivalent chromium (Cr ¹¹¹ ), thereby inhibiting allergic reactions to 6-valent chromium (EP 0125267 Al, EP No. 0160747 A1, EP 0160746 A1, EP 0133434 A1, EP 0054314 A1).

During storage of cements and / or dry cementitious preforms in commercially acceptable containers, ferrous sulphate loses its reducing properties (storage effect) over time. In addition, iron sulphates that enter the lungs cause fibrogenic changes in the lung tissue, so that the use of finely ground iron sulphate from the standpoint of occupational hygiene appears to be risky.

EP no. 0524999 Manganese sulphate is proposed for use ^{in the} reduction of Cr ^{VI in} water soluble Cr ^{VI in} cement adhesives, mortars and concrete. However, whether or not manganese sulfate is used to prevent the potentially harmful health effects of ferrous sulfate, and whether it can solve the problem of overpopulation, is at least questionable.

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The object of the invention is to find a way to reduce the allergenic effect of water-soluble Cr ^{VI in a} water / cement mixture by using an agent that preserves its effect properties in dry cement mixtures for almost indefinitely, is safe from work hygiene and is inexpensive to obtain.

This problem is solved by using the features of point 1. Other preferred improvements of the invention are described in the following claims.

The present invention uses lignin sulfonates. It is impractical for lignin sulphonate to be added to cement and / or cementitious preparations. It can be added, for example, to the clinker immediately before or during milling, to the ground cement before or during the dry cement mixture, or before or during the addition of water to the fresh cement mixture; lignin sulphonate may be added as a commercially available powder or as a solution.

How lignin sulfonates act on water soluble Cr ^VI has not yet been elucidated. It has been found to be most convenient to use 300 mg of lignin sulfonate 1 mg Cr ^VI , provided that the cement contains from about 0.0005 to 0.0015 mg, if necessary up to about 0.004% by weight, of water soluble Cr ^VI ; in the case of more or less water soluble Cr ^VI , appropriate quantities of lignin sulphonate may be added.

Lignin sulphonates are known as salts of ligninic acid, a naturally occurring lignin derivative of wood; they have a basic phenolic structure where the strong phenolic properties are neutralized by etherification of the phenolic OH group. As a high molecular weight natural material ligLT 3519 B ninsulphonates are polymeric heterogeneous; they consist of a mixture of molecules of varying degrees of condensation, where, for example, the molecular weights of the crude lignin sulfonates of unpurified and pine can range from 500 to 50,000. In contrast, technical lignin sulphonates from beech wood have molecular weights not exceeding 10,000.

For many years, lignin sulphonates have been used as dispersants in cement mixtures. Today, they have been replaced in many ways by more appropriate, better-functioning measures. Deep-well cementitious mixtures use, for example, iron lignin sulphonates, which at higher temperatures must control the setting time.

It is known that lignin sulphonates, in the form of sodium or calcium lignin sulphonates in cement mixtures, act essentially as liquefiers and form pores in the air, and can also influence the binding time, mainly due to the liquefaction effect. The numerous types of commercially available lignin sulphonates such as sodium, calcium, iron, chromium-iron, etc. are essentially not suitable for suppressing the water soluble Cr ^VI allergenicity. Since the mechanism of the reaction is not yet known, the present invention requires empirical investigation of the type of lignin sulfonate that effectively affects the water-soluble Cr ^VI reduction. However, it has been found within the scope of the invention that ferric lignin sulphonates reduce Cr ^VI more efficiently than other types of lignin sulphonate, thus requiring, in the same manner, lower amounts of ferric lignin sulphonate than other amounts of lignin sulphonate.

Using the following examples, the invention is explained in more detail below.

example

To 1 kg of dry Portland cement of the three cement grades 1, 2 and 3 different amounts of ferric lignin sulphonate are added and then mixed with water. The Cr ^VI content is then determined analytically. The results are shown in Table I below.

Table I

1 cement 2 cement 3 c ement mgLS * / ~ ^VI Cr mgLS / Cr ^VI mgLS / "Vi Cr mgCr ^VI (% by weight) ~ ^VI mgCr (% by weight) ~ VI mgCr (% by weight) 0 1.37.10 ³ 0 1.0.10 ^-3 0 3, 0:10 ^-3 73 0.77. 10 ^-3 100 0, 6.10 ^-3 33 1, 93.10 ^-3 146 0.26.10 ^-3 67 1.20.10 ^-3 219 0.009.10 ^-3 100 0.57.10 ^-3 292 <0.001.10 ^-3 400 <0.001.10 ^-3 133 0.41.10 ^-3 - 200 0.005.10 ^-3

LS = lignin sulphonate

Assuming that the water-soluble Cr ^VI content is less than 0.1 10 ³ wt%, it can be stated that 300 mg of the test lignin sulfonate additive 1 mg Cr ^{VI is} already sufficient to exceed this limit.

example

As in Example 1, various amounts of calcium lignin sulphonate were added to 1 kg of Portland cement of the same cement type 2. The results are shown in Table II.

Table II

Cement without Annex Cr ^VI (% by weight Cement with 100 mg LS 2 / mgCr ^VI 1.0. 10 ' ³ Cement with 400 mg LS2 / mgCr ^VI 0.31 .10 ' ³

LS = lignin sulphonate

It has been found that more than 400 mg Ca-lignin sulphonate should be added to 1 mg Cr ^VI to achieve sufficient inhibition of the water soluble Cr ^VI allergy.

Example 3 kg of other portland 1,32.10 containing ^3% by weight of water-soluble Cr ^n, was then mixed with various types of lignin sulfonate and water, and then was anali15 Cr ^VI content is subject. The results are shown in Table III.

Table III

With 7 6 mg LS / mg Cr ^VI Cr ^VI (% w / w) With 300 mg LS / mg Cr ^VI Cr ^VI (% w / w) LS'l i, 05.10 ³ 0.25.10 ³ LS2 1.09.10 ^-3 0, 31.10 ³ LS3 1.06.10 ³ 0, 60.10 ' ³ LS4 0, 93.10 ³ 0.23.10 ' ³ LS5 0.73.10 ' ³ 0, 01. IO ' ³ LS6 0.74.10 ' ³ 0.06.10 ³ LS7 0, 67.10 ' ³ 0, 07.10 ' ³

LS = lignin sulphonate

LSI: Calcium lignin sulphonate LS2: Sodium lignin sulphonate LS3: Sodium lignin sulphonate LS4: Iron-chromium lignin sulphonate

LS5: Iron lignin sulphonate

LS6: Calcium lignin sulfonate

LS7: Sodium lignin sulphonate

Table III shows that 5, 6, and 7 ligninsulfonate 300 mg LS / mg Cr ^VI is effective and the Cr ^vr concentration in the cement is reduced below 0.1.10 to ³ wt.% Of water soluble Cr ^VI .

If the cements or cementitious preparations already contain lignin sulphonates for other purposes, it must be checked whether and to what extent these lignin sulphonates can contribute to the deleterious effects of water-soluble Cr ^VI . According to the invention, additional amounts of lignin sulfonate, respectively, are required for the suppression of allergic activity, if necessary.

By the use of lignin sulphonate according to the invention, side effects such as liquefaction and / or formation of air pores and / or effect on the binding time can be controlled by appropriate means. These types of tools are known. For example, the liquefying action of lignin sulfonate can be eliminated by the addition of finely dispersed substances. However, it should be noted that not every lignin sulphonate acts as a liquefier. It is therefore necessary to check on a case-by-case basis whether a liquefying effect occurs and with what quantities of fine dispersible material this effect can be controlled. For example, when using lignin sulfonate LSI according to Table III, a 10 wt% microsilicate additive, based on the weight of the cement, compensates for the liquefaction effect. When using LS3 according to Table III, 5% by weight of microsilicate is sufficient to compensate for the liquefying effect of lignin sulfonate. In the case of iron lignin sulphonate LS5 according to Table III, there is no liquefaction,

Thus, rheological compensation is not necessary in this case.

example

It follows from the example below that the effect of lignin sulphonate is also the case when commercially available products are combined with lignin sulphonate when added to water. For two types of building materials, the adhesive for tiles and mortar for the filling of cracks with LS was determined by the water soluble Cr ^VI before and after the addition of iron lignin sulphonate according to Table III. The results obtained are shown in Table IV below.

Table IV

Adhesives for tiles Mortar for patch filling mgLS / mgCr ^VI Cr ^VI (% by weight) mgLS / mgCr ^vl Cr ^VI (% by weight) 0 0.5.10 ³ 0 0.35.10 ³ 200 0.23.10 ³ 286 0, 1 .io ' ³ 400 0 ·, 05.10 ' ³ 571 0, 05.10 ' ³

LS = lignin sulphonate

Cement-containing preforms according to the invention are, for example, mortar, tile adhesive, cracking mortar, plaster or the like.

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DEFINITION OF INVENTION

Claims (7)

DEFINITION OF INVENTION 1. A method of suppressing the allergenic effect of water-soluble Cr ^VI in cements and / or cementitious preparations, characterized in that a large number of commercially available lignin sulphonates have been found by preliminary testing to lignin sulphonate upon contact with water and / or cement-containing preform reduces the amount of water-soluble Cr ^VI in the desired manner and adds this selected lignin sulfonate to the cements and / or cement-containing blanks against or after water added, in production fresh cement mixtures. 2. The way according to 1 point, Come on appoint n t i s in that uses of iron lignin sulfonate. 3. The way according to 2 point, Come on appoint n t i s in that makes j from 200 up to 400 mg / mg Cr ^VI of iron of ligninsilphonate. 4. The way maybe 1 above exclusive in that used a calcium lignins lfonate. 5. The way according to 4 above exclusive by adding 200 to 500 mg / mg of Cr ^VI calcium ligninsulfonate. 6. A process according to one or more of claims 1 to 6, characterized in that the addition of fine dispersible water-binding substances is added to compensate for the liquefaction effect of the lignin sulphonate. 7. A process according to claim 6, which comprises addition of from 1 to 10% by weight of finely dispersed silicic acid (microsilicate), based on the amount of cement. 8. A process according to claim 6 and / or 7, which comprises addition of from 1 to 20% by weight of finely dispersed calcium carbonate, based on the amount of cement. 9. A process as claimed in one or more of claims 1 to 8, which comprises adding a known stiffening accelerator. 10. The method of claim 9, wherein calcium formate is added as a stiffener. The process according to one or more of claims 1 to 10, characterized in that the lignin sulfonate is added before or during the clinker mill.