CA1048670A

CA1048670A - Process for preparing a hardenable coating composition

Info

Publication number: CA1048670A
Application number: CA75221217A
Authority: CA
Inventors: Isam Makansi; Pieter De Bruin
Original assignee: Shell Canada Ltd
Current assignee: Shell Canada Ltd
Priority date: 1974-04-09
Filing date: 1975-03-04
Publication date: 1979-02-13
Also published as: BE827491R; NL7504088A; AU7987875A; IT1049400B; ZA752186B; FR2267355A2; GB1483198A; JPS5117911A; FR2267355B2; DE2515042A1

Abstract

A B S T R A C T

Hardenable coating compositions, suitable for application by trowelling, are prepared by mixing one part by weight of a resinous binder with from 10 to 100 parts by weight of a filler, and adding 0.5 to 2 parts by weight of a dilute aqueous solution of a polysaccharide compound.

Description

1~48~70 The invention relates to a hardenable coating com-position which is suitable for application onto a surface by trowelling. The invention is a modification of the invention described and claimed in Canadian patent application No. 165.321 which claims a process for preparing a hardenable coating composition suitable for application onto a surface by trowelling, comprising mixing one part by weight of a liquid water-insoluble resinous binder with from 5 to lO
parts by weight of small inert particles, and adding to the mixture with stirring from 0.5 to 2 parts by weight of a dilute aqueous solution of a water-soluble polysaccharide compound. Compositions as claimed in the aforesaid patent specification are particularly useful to cover a surface, such as floors or walls, with a layer which when cured is impermeable for contaminants and which thereby protects the underlying surface; specific advantages are that such com-positions do not stick to tools such as mixer or trowel, and that they are smoother and more kneadable than corre-sponding compositions which do not contain the dilute aqueous solution of polysaccharide compound.
It has now been found that such compositions which contain considerably more than lO parts by weight of small inert particles per part by weight of water-insoluble binder can also be applied by trowel, and can find particular use in cases where permeability for water and other liquids can be allowed, such as for egalization of very rough substrates, or as filling material, e.g., for damaged concrete before a top layer is applied, in particular when the surface will be covered with an impermeable top layer.
For applications as described above, sand-cement mortars are often used; these, however, have the disadvantage of dusting during pouring the cement and making the mortar; further they have to be kept wet for a rather long time (more than a week) for development of optimum strength;
also the hardened sand~cement mortars are not acid-resistant. ~ -The novel compositions, on the other hand, do not or scarcely dust during preparation, and the layers applied need only about 24 hours to harden and dry; further the layers are acid-resistant.
Thus this invention seeks to provide a process for preparing - -a hardenable coating composition suitable for application onto a surface by trowelling, comprising mixing one part by weight of a liquid water-insoluble resinous binder with between 10 and 100 parts by weight of small inert inorganic partîcles having a particle size of at least 74 microns, and adding with stirring 0.5 to 2 parts by weight of a dilute aqueous solution of a water-soluble polysaccharide compound, wherein the liquid resinous binder comprises an epoxy resin and a water-insoluble amino com-pound having per molecule on average at least two amino hydrogen atoms, or an unsaturated polyester.
The liquid resinous binder comprises as the hardenable compo-nent preferably an epoxy resin, and as a hardener for the epoxy resin a water-insoluble amino compound having per ~_ !

1C~4B670 molecule on average at least two amino-hydrogen atoms.
Epoxy resins containing from 80 to 100% by weight of a polyglycidyl ether of 2,2-bis(4-hydroxyphenyl)propane, having an average molecular weight between 340 and 500, are preferred; these polyglycidyl ethers are usually viscous liquids at ambient temperature. The remainder, if any, of the epoxy resin may be a liquid epoxide of low viscosity, such as butyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, glycidyl esters of saturated aliphatic monocarboxylic acids having from 9 to 11 carbon atoms per moleculej wherein the carbon atoms of the carboxyl group are bound to a tertiary or quaternary carbon atom, diglycidyl ether of ethylene glycol, or diglycidyl ester of 2,2,4-tri-methyl adipic acid; these epoxides of low viscosity act as reactive diluents for the viscous polyglycidyl ether, and reduce the viscosity to the desired level.
The amino compound used in the present process in com-bination with the epoxy resin should be water-insoluble, that is to say that it should not dissolve readily or to an appreciable extent in water in the weight ratios in which the amino comppund and the aqueous solution are used. Water-soluble amino compounds dissolve in the aqueous phase in the present process, which retards the cure or even may prevent complete cure.

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~48~70 Suitable water-insoluble amino compounds as defined above are in general reaction products of aliphatic, cyclo-aliphatic or aromatic primary polyamines with epoxides, or with phenols and aldehydes. Examples of primary polyamines suitable for preparing such water-insoluble amino compounds are: ethylene diamine, diethylene triamine, di(4-amino-cyclohexyl)methane, dit3-methyl-4-amino-cyclohexyl)methane, isophorondiamine(3,5,5-trimethyi-3-aminomethylcyclohexyl-amine), xylylene diamine(di-(aminomethyl)benzene), diamino diphenyl methane, and diamino diphenyl sulphone. It is noted in this connection that even for aliphatic poly- -amines which are readily soluble in water, such as di-ethylene triamines, the modification by reaction with an epoxide, or with phenols and aldehydes can reduce the water solubility to an acceptable level.
Examples of water-insoluble amino compounds are re-action products of primary polyamines with monoglycidyl compounds in a 1:1 molar ratio. Suitable monoglycidyl com- -pounds for forming such reaction products are, for example, phenyl glycidyl ether, cresyl glycidyl ether, and glycidyl esters of saturated aliphatic monocarboxylic acids having from 9 to 11 carbon atoms per molecule wherein the carbon atom of the carboxyl group is bound to a tertiary or quaternary carbon atom.

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1~48670 Very suitable water-insoluble amino compounds are -reaction products of primary polyamines with polyglycidyl ethers of 2,2-bis(4-hydroxyphenyl)propane having an average molecular weight between 340 and 500 in molar ratios of polyamine to polyglycidyl ether of between 1:0.1 and 1:0.2, and optionally with glycidyl esters of saturated aliphatic monocarboxylic acids having from 9 to 11 carbon atoms per molecule, wherein the carbon atom of the carboxyl group i~ bound to a tertiary or quaternary carbon atom, in molar ratios of polyamine to glycidyl ester between 1:0.4 and 1:0.6.
Other very suitable water-insoluble amino compounds are condensates having at least two amino hydrogen atoms per molecule of primary diamines with phenols and aldehydes, such as formaldehyde, for example, the condensates described in the British patent specifications 789,475 and 868,892 and in the German patent application 1,953,643. Condensates of this type contain free phenolic groups which accelerate the cure of the epoxy resin.
The water-insoluble amino compound may be diluted with small amounts of solvents to improve the fluidity and to facilitate mixing with the epoxy resin.
The water-insoluble amino compound and the epoxy resin should be kept stored separately, and these two components ~hould be mixed only shortly before use, as the components ..-: , . . . :

~48670 begin to react slowly immediately after being mixed, and the pot life (the time that the mixture is sufficiently fluid to be worked) is rather short.
The ratio of epoxy resin and amino compound is as usual in the art, that is in general from o.8 to 1.2 amino hydrogen equivalent per epoxy equivalent.
The liquid resinous binder which contains epoxy resin may contain additional components, for example, low-volatile liquid extenders, such as pine oil, coal tar, refined coal tar or aromatic extracts of petroleum distillates. Other useful additives are curing accelerators, such as phenolic compounds, for example, phenols such as phenol, cresols, xylenols or preferably salicylic acid.
Other types of liquid resinous binders are, for example, ;
unsaturated polyesters, optionally modified by addition of styrene, and hardenable with free-radical catalysts or metal salts.
The aggregate or filler used in the present invention is com?osed of small inert inorganic particles having a particle size of at least 74 microns, preferably between 74 microns and 2.0 mm, more preferably between 0.1 and

2.0 mm. A suitable aggregate is sand, but other filler materials may be added. A graded sand may also be used, such as a graded sand having a particle size between 0.1 and 2.0 mm. Part of the aggregate may be of larger size than 2 mm.

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16)48670 The amount of aggregate or filler is in general from 10 to 100, preferably from 20 to 80, parts by weight per part by weight of liquid resinous binder. When the aggregate is sand with a particle size distribution in the range of from 0.1 to 2 mm, and preferably from 0.2 to 2 mm, the present compositions and the resulting hardened layers made therefrom may have the following characteristics:
(1) Filler/binder weight ratio between 10:1 and 20:1; compo-sition easily trowellable, cured layer has usually low permeability for water and high strength. Use in top layers for floors and walls (when high strength is required, and some permeability for water can be tolerated) and stopping compounds, e.g., for damaged concrete, without application of a surfacing compound.
(2) Filler/binder weight ratio 20:1 to 60:1; composition trowellable, cured layer is permeable for water and organic liquids and has a strength higher than or comparable with the strength of fully hardened sand/cement mortars. Use for egalization of very rough surfaces on places where impermeability is not required or before application of an impermeable top layer.

(3) Filler/binder weight ratio between 60:1 and 100:1; compo-sition still trowellable, cured layer permeable for water and organic liquids, with strength comparable with or ... - . - , . ~ , ~ , : . .

1~48~i70 lower than the strength of fully hardened sand/cement mortars. Use for egalization of rough surfaces where strength does not matter, such as on certain types of walls, and on floors where resistance to local forces is completely taken up by a high strength top layer.
For the purpose of the present invention a dilute aqueous solution of a water-soluble polysaccharide compound is added to the mixture of liquid binder and aggregate.
In this context dilute is preferably an amount of from -0.25 to 1 per cent by weight of polysaccharide compound in the water. Polysaccharide compounds are those poly-saccharides and derivatives thereof, such as ethers, which do not resemble sugars.
The water-soluble polysaccharide compound may be a true polysaccharide such as starch or dextrine. Starch may be dissolved in hot water, whereafter the solution is cooled for use in the present in~ention. Dextrine - a hydrolyzed starch - can usually be dissolved in cold water.
The polysaccharide compound may also be a polysaccharide ether, such as a cellulose ether, that means a cellulose in which free hydroxyl groups of the cellulose have been converted into ether groups. Examples are methyl cellulose, hydroxyethyl cellulose, and salts of carboxymethyl cellulose (CMC).

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1¢J 48670 In the present process the sequence of adding the various components bears some weight. The liquid resinous binder is usually added to the aggregate in a type of dough kneader or concrete mill. When the mass is homogeneous after some minutes, the aqueous solution of polysaccharide compound is added, and the mixing is continued for a short time, usually below 1 minute when the total amount of the mixture is small. The mass can then be removed from the mixer, and stored, if desired, for a short time.
The mixture of aggregate and liquid resinous binder has a consistency which varies with increasing aggregate/binder ratio from crumbly to merely wetted sand. On addition of the dilute aqueou~ solution in the rather small weight ratios specified above the consistency changes into that of a trowel~ble mass.
The surface to be covered with the mass so prepared is preferably first covered with a thin "tack" coat of liquid resinous binder without aggregate, to ensure good adhesion.
The filled, thoroughly blended mass can then be spread evenly over the desired area by means of a trowel, roller, screed, or vibratory screeder, and if desired, finished with a trowel. Trowel, roller and screed are preferably from poly-ethylene or polypropylene, to better prevent any sticking of the material to it. ~ -:

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, 48t~70 Mixer and trowel or other apparatus can be easily cleaned with water, or by wiping with a wet cloth.
The surface to be covered may be concrete, stone, steel, asbestos cement or wood; if the surface is dirty it has first to be cleaned as known in the art; for concrete the last stage of cleaning is usually an etching with dilute hydro~
chloric acid, followed by cleaning with water, and drying;
steel can be cleaned by treatment with a degreasing solvent followed by sand blasting, brushing or grinding; wood is preferably taken down to clean wood with a sander.
After application of the coating the layer is allowed to cure during which time the water can also evaporate.
The cure is usually performed at ambient temperature;
accelerated cure (and evaporation of water) may be attained by moderate heating, for example with an infrared ~ating device.
Surfaces of cured masses according to the invention can, if dèsired, be covered with top layers or surface coatings or surfacing sheet material, loose or glued onto the layer prepared according to the invention.
For improving the adhesion when a resin-containing mortar is used for the top layer, it is preferred to first impregnate the surface with a "tack" coat of liquid resinous binder without any aggregate. The surfacing mortar may be of the type as described in the aforesaid patent specification, --11- ' :

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-~48670 with or without aqueous polysaccharide solution. The top layer may also be a self-levelling compound, that is a resinous composition containing such an amount of filler that the composition upon pouring and perhaps slight egalization levels out itself into a smooth level layer before the hardening sets in.
The cured layer made according to the invention may also be covered with a ~int coating, that is a thin layer of a flowable composition which hardens by evaporation of liquid, and/or by the action of cross-linking agents. A further means '~ to cover a layer as described is by surfacing with a sheet -- material, such as tiles or sheets of materials, such as linoleum, colyvinyl or a carpet material.
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~he invention is illustrated by an example. The epoxy ; 15 resin was a liquid polyglycidyl polyether of 2,2-bis(4-hydroxyphenyl)propane diluted with 9% by weight of cresyl glycidyl ether; the viscosity was 50-60 poise at 25C.
Curing agent A was a liquid adduct of xylylene diamine with a liquid polyglycidyl ether of 2,2-bis(4-hydroxy-phenyl)propane and glycidyl esters of saturated aliphaticmonocarboxylic acids having from 9 to 11 carbon atoms per molecule, wherein the carbon atom of the carboxyl group is bound to a tertiary or quaternary carbon atom, in molar ,, .- , ratios of 1:0.16:0.53, diluted with 18 pbw benzyl alcohol; -it was applied in a weight ratio epoxy resin/Curing agent A

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~Q48670 of 1.0:0.7. ;~
Curing agent C was a liquid condensate of xylylene diamine with phenol and formaldehyde, diluted with benzyl alcohol to give a Brookfield viscosity of 3.35 poise at 22C; it was applied in a weight ratio epoxy resin/Curing agent C of 1.0:0.5.
EXAMPLE
The formulations were prepared by mixing the dry filler component (sand) with the binder mixture (epoxy resin and curing agent, mixed in a separate vessel with stirring during 2 minutes). Then a 0.5% by weight solution in water of a commercial hydroxyethyl cellulose was added with stirring (1:1 weight ratio binder mixture/aqueous solution).
A tack coat was applied onto an existing concrete floor (which was first cleaned with methyl ethyl ketone). Then the formulations according to the invention were applied by trowel. After complete hardening (28 days at 23C) the strength was determined.
The resinous binders consisted of epoxy resin and Curing agents A and C in weight ratios as indicated above.
The filler was a graded sand, 65 wt.-% having particle size 1-2 mm and 35 wt.-% having particle size 0.2-0.5 mm.
Flexural and compressive strength were determined according to DIN 1164.

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.. . . . . - - . ~ ' ;` 1~48670 The filler/binder weight ratios were varied, and figures for strength were assorted according to the Table below.

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Filler/ Curing agent ~ Curing agent C

weight Flexural Com-~ FleXural Com- Schmidtsen ratio strength pressive strengt2h pressiv~ Hammer (kg/cm2) strength(kg/cm ) strengt~ strength ;(kg/cm2) (kg/cm2) (kg/cm2, DIN 4240) . 25:1 127 180.5 67 149 260 35:1 108 141.5 58 124.5 225 50:1 102 124 49 94 170 75:1 26 29 150 ' ; - , :
The surface could be walked upon after only 4 hours without damage, and could be sealed or provided with a top layer after 24 hours.

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For comparison, a fully cured layer of a sand/cement/
, water mortar (4:1:0.5 weight ratio) had a flexural and compressive strength of 30 and 110 kg/cm2, respectively, after having been kept wet during 28 days.
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for preparing a hardenable coating composition suitable for application onto a surface by trowelling, comprising mixing one part by weight of a liquid water-insoluble resinous binder with between 10 and 100 parts by weight of small inert inorganic particles having a particle size of at least 74 microns, and adding with stirring 0.5 to 2 parts by weight of a dilute aqueous solution of a water-soluble polysaccharide compound, wherein the liquid resinous binder comprises an epoxy resin and a water-insoluble amino compound having per molecule on average at least two amino hydrogen atoms, or an unsaturated polyester.

2. A process as claimed in claim 1 wherein the liquid resinous binder comprises an epoxy resin and a water insoluble amino compound.

3. A process as claimed in claim 2 wherein the epoxy resin contains from 80 to 100% by weight of a polyglycidyl ether of 2,2-bis(4-hydroxyphenyl)-propane having an average molecular weight between 340 and 500.

4. A process as claimed in claim 2 wherein the amino compound is a reaction product of a primary polyamine and a monoglycidyl compound in a 1:1 molar ratio.

5. A process as claimed in claim 4 wherein the amino compound is a reaction product of a primary polyamine and a glycidyl ester of saturated aliphatic monocarboxylic acids having from 9 to 11 carbon atoms per molecule, wherein the carbon atom of the carboxyl group is bound to a tertiary or quaternary carbon atom.

6. A process as claimed in claim 2 wherein the amino compound is a reaction product of a primary polyamine, a polyglycidyl ether of 2,2-bis(4-hydroxyphenyl)propane having an average molecular weight between 340 and 500, and a glycidyl ester of saturated aliphatic monocarboxylic acids having from 9 to 11 carbon atoms per molecule wherein the carbon atom of the carboxyl group is bound to a tertiary or quaternary carbon atom in molar ratios of polyamine to polyglycidyl ether to glycidyl ester between 1:0.1:0.4 and 1:0.2:0.6.

7. A process as claimed in claim 2 wherein the amino compound is a condensate of a primary diamine with a phenol and an aldehyde.

8. A process as claimed in claim 1 wherein the liquid resinous binder contains additionally a low volatile liquid extender.

9. A process as claimed in claim 8 wherein the low-volatile liquid extender comprises pine oil, coal tar, refined coal tar or aromatic extracts of petroleum distillates.

10. A process as claimed in claim 2 wherein the liquid resinous binder contains additionally a phenolic accelerator.

11. A process as claimed in claim 10 wherein the phenolic accelerator is salicylic acid.

12. A process as claimed in claim 1 wherein the small inert particles have a particle size between 74 microns and 2.0 mm.

13. A process as claimed in claim 1 wherein the amount of small inert particles is from 20 to 80 parts by weight of the liquid resinous binder.

14. A process as claimed in claim 1 wherein the dilute aqueous sol-ution contains from 0.25 to 1 per cent by weight of polysaccharide compound.

15. A process as claimed in claim 1 wherein the water-soluble poly-saccharide compound is starch or dextrine.

16. A process as claimed in claim 1 wherein the water-soluble poly-saccharide compound is a cellulose ether.

17. A process as claimed in claim 16 wherein the cellulose ether is a water-soluble salt of carboxymethyl cellulose.

18. A process as claimed in claim 16 wherein the cellulose ether is methyl cellulose or hydroxyethyl cellulose.

19. A hardenable coating composition prepared as claimed in claim 1.

20. A process for forming a hard coating onto a surface, comprising applying a hardenable composition as claimed in claim 18 onto the surface, and allowing the composition to harden.

21. Hardened coating on a surface, applied by a process as claimed in claim 20.