GB2218993A - SBR latexes - Google Patents

Abstract

A styrene-butadiene latex having carboxylic, sulphonic and amine groups present therein is formed by solubilising an anionic SBR latex with an adduct of an alkyl amine and a poly(oxyethylene), the anionic SBR latex containing carboxylic groups and having been emulsion polymerised using a sulphonate, prior to solubilisation. The functional groups mean that the latex can complement both positive and negative electric charges. Such SBR latexes may be mixed with organic and inorganic fibrous materials, polymeric fibres, cements and aggregates and may also be used for scattering on the surface of sandy soils or for coating surfaces of metal or concrete products.

Description

SBR Latexes The present invention relates to cationic SBR latex polymer emulsions used for scattering, coating, bonding, blending, impregnation or the like, as well as for adding to industrial products in the field of civil and construction engineering.

Cationic polymerisation of latexes is not preferable from the point of view of cost and products. so commercially available anionic latexes to which amine groups have been introduced are employed. In this context see, for example, (1) U.S. Patent No. 3660324, (2) British Patent No. 1281785, (3) Japanese Patent No.

710008, (4) Japanese Patent No. 710028, (5) Japanese Patent No. 896294. (6) Japanese Patent No. 949349, (7) Japanese Patent No. 949344, (8) Japanese Patent No.

1081747 and (9) Japanese Patent No. 1260405.

Latexes of natural or synthetic rubbers, mainly SBR latex and, particularly, commercially available anionic products, are cationically modified and used as reinforcing agents for sands and soils or cements, and are referred to as 'cationic' latexes.

As most materials on the earth, such as wetted surfaces, exhibit negative charge, cationic latexes allow effective application through positively charged rubber particles in the latex.

It is considered that the main reason why wetted surfaces of such materials exhibit negative charge is owing to negative ions of silicate polymers, which are present as a major component of the earth's crust.

4- Silicic acid itself is anionic (Sia4 6- Ski207 ). However, as there are various rocks containing, for example, amino silicates or boro-silicates, in which a portion of silicic acid is substituted, or those containing paracitic calcium or other metals, the anionic nature becomes weak and they often demonstrate positive charges (cationic nature).

similarly, for blending with cements, silicate ions of aggregates such as sands are considered important and, in addition, it is necessary for the latexes to be adaptable to cationic materials such as calcium, aluminium oxide, sodium, potassium, etc. upon hydration. In such instances, the known latexes are not sufficient.

The present invention thus provides a styrene butadiene latex containing carboxylic, sulphonic and amine groups.

The present invention also provides a process for the preparation of a cationic SBR latex comprising solubilising an anionic SBR latex with an adduct of an alkyl amine and a poly(oxyethylene), the anionic SBR latex containing carboxylic groups and having first been emulsion polymerised using a sulphonate emulsifier.

Where positive charges are present at the surface of rocks, rock chips, metal surface, soils and sands, for example, those containing calcium, aluminium, etc. or where positive ions are formed vigorously as in the cement hydrating reaction, the present invention enables the provision of macro rubber molecules with (A) cationic nature due to amines of positive charges corresponding to the inherent existence of silicate ions (negative charges), as well as with (B) carboxylic groups and sulphonic groups for complementing the various positive charges.

The above problems of the prior art are overcome by the SBR latexes of the present invention, which have those functional groups, for example amine groups. carboxylic groups and sulphonic groups, which are capable of complementing both negative and positive charges of soils and sands, rocks and cements, for example.

In another aspect, the present invention provides a process for producing moulded products using the above SBR latex to produce boards, poles and other moulding products by adjusting the solid content of the SBR latex to 2-50% concentration, mixing them together with various kinds of fibrous materials a such as wood fibres, for example saw dust and wood chips. mineral fibres such as glass or metal, and polymeric fibers such as polyester, or portland cement, with or without aggregates.

A solution of the SBR latex according to the invention, diluted to about 2-10% solid content, may be sprayed on the surface of sandy soils. Such SBR latexes may also be adjusted to about 2-50% solid content and coated on to the surface of reinforcing steels and steel constructions to form a corrosion-proof layer, or coated on to the surface of concrete products to form adhesion layers to the reinforcing steels and steel constructions.

Accordingly, SBR latexes in accordance with the present invention have an affinity for, and strongly bind those substances having positive electric charges, as well as those having negative charges such as soils, sands and rocks. Adhesion is greatly improved, as well as other factors, such as workability and stability.

The cat ionic SBR latexes of the present invention may be obtained by solubilising known anionic SBR latexes with an alkyl amine which is condensated (adducted) with polyoxyethylene. The anionic SBR latex should preferably satisfy the following conditions: (1) It has a styrene:butadiene ratio of about 80:20 to 40:60; (2) It comprises carboxylic groups; (3) It has been emulsified by an aromatic compound having a sulphonic group as the main emulsifier or has been emulsified by an emulsifier having a sulphonic group and polymerised together with mono-and dicarboxylic acid.

The superior effects of the present invention are thought to be because patents (1)-(5) do not use sulphonic groups for emulsion polymerisation in their preparation. Patents (6)-(9) use sulphonic groups but do not use carboxylic groups. However, the cationic SBR latexes of the present invention are obtained by using anionic SBR latexes comprising carboxylic groups as starting materials, and using emulsion polymerisation with an emulsifier having sulphonic groups, such as described in Example 1 below. Sulpho-amide bonds are formed by introducing amine groups into anionic SBR latexes comprising carboxylic groups and emulsion polymerised using a sulphonic emulsifer. The cationic SBR latexes of the present invention have both negative and positive charges owing to the presence of the sulpho-amide bond.

The effect of the present invention is demonstrated by the following Table, comparing the products of the known patented inventions and the products of the present invention. The numbers correspond to the patents discussed above.

TABLE

Type of cation latex Known patented Known patented Product of the Items for \ invention invention present inven the effect \ (1) ~ (5) (6) ~ (9) tion Stabilization Effective to Effective to Applicable for for soil and soil and sand soil and sand all of objects sand layer layer enriched layer enriched with no substan (anti-land- in silicate in silicate tial limit slide. desert ions ions. and. to greening) some extent. to those containing calcium alumino silicate. etc.

Overall effectiveness 0 Oo Mixing with cement. work ability. x Qo performance of mortal concrete Overall adhesion Stability to liquid con centrate such 0 as of magnesium chloride In the Table respective symbols means: excellent 0: usable : not usable X: coagulated The specific examples of the present invention vary remarkably depending on the conditions of soils and sands, rocks or cements to which the latexes of the invention are applied.

EXAMPLE 1 (1) Examples of anionic SBR latexes which may be used as starting materials include those latexes designated as JSR 0668, 0691, 0693, 0695, 0696, 0697, 0617, 0619, or equivalent products, available from Nippon Gosei Rubber Co., and Crossren (trade mark) SK72 available fromTakeda Yakuhin Co., as well as those products having similar performance available from other companies, that is, latexes having a styrene:butadiene ratio of about 80:20 to 40:60.

These products have a carboxylic group content of up to about 10%, based on the amount of styrene and butadiene, in which carboxylic acids may be either in the form of a polymer or oligomer. These latexes have been prepared by emulsion polymerisation using an aromatic compound with the sulphonic group as the main emulsifier.

Other suitable products have the same constitution as those described above, which have been emulsified by an emulsifier having sulphonic groups and polymerised together with mono- and dicarboxylic acid include, for example, Dow Latex 620A, 638A, 640A, etc. (Dow Chemical Co.) or Polysar Latex 3515, 3528, 3560, etc. (Polysar Co., in Canada).

(2) For solubilising these SBR latexes, an alkyl amine condensated with polyoxyethylene without bonding to a base is introduced, for example, a compound of formula:

(wherein R is an alkyl group having from 6 to 22 carbon atoms, R is a hydrogen atom or a methyl group, each of the symbols n is the same or different and is an integer, the sum of their total being 1 to 30, preferably 5 to 25, R2 is an alkylene group having 3 from 1 to 4 carbon atoms. m is 0. 1 or 2, and R is a hydrogen atom or a group of formula:

wherein R1, RZ, n and m are as defined above).

Suitable, easily available commercial products include "Esomine" (trade mark) from Armor Co., "Naimine" (trade mark) from Nippon Yushi Co., and "Diameat (trade mark)of Kao Corp. They are properly referred to as the modifying reaction agent rather than the surface reaction agent.

(3) The cationic SBR latexes of the present invention can be obtained by introducing the amine group with addition of from 3 to 5% of them described in (2) above to the latex described in (1) above (about 50% concentration).

EXAMPLE 2 For desert greening or for anti-landslide of soil and sand layers, it is effective to scatter a solution prepared by diluting the cationic SBR latex according to the present invention to a solid content of about 2-10% either manually or by engine driving, or by way of a helicopter for a larger area. While the objects to be treated have been limited so far to those places such as deserts or seashores abundant in silicic sands, the SBR latex of the present invention may also be usefully employed in complicated lays of land, such as volcanic zones. In addition, vegetation mixed with plant seeds are also effective.

EXAMPLE 3 Commercially available Crossren (trade mark) SK72 is cationically modified by the method of Example 1 and then applied as the material for the production of wood fibre cement boards for use in civil and construction engineering. Although it is possible to directly mix it with cement, the cationically modified SBR latex is preferably mixed with a magnesium chloride solution and put to a continuous moulding step together with saw dust, wood chips or cement in view of the improvement for the production step. While usual latex coagulates if magnesium chloride is added, the latexes of the present invention do not.

EXAMPLE 4 SBR latex (used for paper coating, such as, for example, JSR0669) is cationically modified by Esomine (trade mark of Armar Co.), scattered to soil and sand layers containing a relatively large amount of, for instance.

calcium, clay content, for applying anti-landslide. If the soil and sand layers contain a great amount of silicate ions, a cationic latex containing no sulphonic groups (for example as disclosed in patents (l)-(6) above) may be used. No specific manuals are indicated, because samples of soils and sands vary remarkably depending on the places they are sampled and preparations can not be defined unless appropriate experiments are conducted.

The concentration of the solid content in the above mentioned latex has to be controlled depending on the method of manual spraying, or method of scattering and impregnation by means of track or helicopter, but the concentration of the solid content is generally adjusted to about 3-15% with addition of water.

EXAMPLE 5 The cationic SBR latexes of the present invention was charged and mixed into a concrete mixer such that the polymer was from 0.5 to 3% based on the cement content The mixing ratio was adjusted depending on the degree of silicate ions in the aggregates used.

EXAMPLE 6 A mixture of from 0 to 400% of silicic sand of small grains and from 7 to 20% of rubber content based on 100% of the cement exhibits a bonding strength similar to that of usual epoxy resin, although somewhat differentdepending on the objects to be bonded. The SBR latexes of the present invention compare favourably with ordinary commercially available polymer emulsions for mixing cement (for example vinyl acetate, acrylic, SBR, CR system) after ageing the material for four weeks.

However, the other products gradually lose strength, whereas the products of the present invention show a definite improvement in strength for more than a year and exhibit outstanding excellence even under conditions of high temperature and vigorous vibration. Products of the present invention manufactured for testing show strength which has been increased even put to continuous use under severe conditions for more than ten years.

EXAMPLE 7 A cationic SBR latex of the present invention, diluted with water (to 1-30% solid content), is scattered, poured and penetrated as a primer paint, crack-repairing or leakage-proof filler. It shows intense penetration and forms rubber membranes to fill depleted portions at the extreme point. The benefits are, thus, evident.

It is also possible to mix and apply a cationic asphalt and other adhesive resin emulsion with the cationic SBR latex as described above.

Claims (12)

1. A styrene butadiene latex containing carboxylic, sulphonic and amine groups.

2. A latex according to claim 1 wherein the styrene:butadiene ratio is between about 80:20 and about 40:60.

3. A process for the preparation of a cationic SBR latex comprising solubilising an anionic SBR latex with an adduct of an alkyl amine and a poly(oxyethylene), the anionic SBR latex containing carboxylic groups and having been emulsion polymerised using a sulphonate, prior to solubilisation.

4. A process according to claim 3 wherein the anionic SBR latex contains up to about 10% carboxylic groups.

5. A process according to claim 3 or 4 wherein the alkyl amine/poly(oxyethylene) adduct has the formula:

(wherein R is an alkyl group having from 6 to 22 carbon R 1.

atoms R is a hydrogen atom or a methyl group, each of the symbols n is the same or different and is an integer, the sum of their total being 1 to 30, preferably 5 to 25, R2 is an alkylene group having 3 from 1 to 4 carbon atoms, m is 0, 1 or 2, and R is a hydrogen atom or a group of formula:

wherein R1R2, n and m are as defined above).

6. A SBR latex, wherein functional groups such as amine group, carboxylic group and sulphonic group are provided together, thereby enabling it to correspond both to negative and positive electric charges in soils and sands, rocks and cements.

7. A process for producing the SBR latex as defined in Claim 6, wherein amine groups are introduced into an anionic SBR latex at about 50% concentration by adding 3 to 5% of an alkyl amine condensated with polyoxyethylene without bonding to a base.

8. A method of manufacturing a moulding product using a SBR latex, wherein the solid content in the SBR latex having functional groups such as amine group, carboxylic group and sulphonic group together to 2-50% concentration, and they are mixed with portland cement together with various kinds of fibrous materials, for example, wood fibres such as of saw dusts, wood chips, etc., mineral fibres such as glass and metals and polymeric fibers such as polyester with or without mixing aggregates, thereby manufacturing boards, poles and other moulding products.

9. A method of using a SBR latex, wherein a solution prepared by diluting the solid content of SBR latex having functional groups such as amine group, carboxylic group and sulphonic group together to about 2%-10% concentration is scattered on the surface of sand soils.

10. A method of using a SBR latex, wherein the solid content of the SBR latex having functional groups such as amine group, carboxylic group and sulphonic group together to about 2-50% concentration, and they are coated to the surface of reinforcing steels or steel construction to form corrosion-resistant layers or coated to the surface of the concentrate products to form adhesion layers to the reinforcing steels or steel constructions.

11. A SBR latex substantially as described herein with reference to the accompanying Examples.

12. A process substantially as described herein with reference to the accompanying Examples.