CA1047186A - Method of applying mastic paint compositions to concrete bases - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A mastic paint composition for concrete is provided which comprises (a) Portland cement, (b) an aggregate, (c) from 1 to 3 parts by weight of calcium chloride, (d) from 0.4 to 2 parts by weight of a naphthalene sulfinic acid formalin condensate, (e) from 1 to 2 parts by weight of an alkylcellulose said parts being by weight based on 100 parts by weight of the Portland cement.
Further at least one known addition selected from dry preventive agents, shrink prevention agents, efflorescent prevention agents, waterproofing agents, and defoaming agents may be present. The aggregate is present in an amount of from 100 to 150 parts by weight based on 100 parts by weight of the Portland cement. This composition can be made by kneading these components in the presence of water into a paste. In applying this composition to a concrete base, it is not necessary to treat the surface of the base beforehand. The composition can be applied with a porous hand-roller directly to the untreated concrete base, and a satis-factory mastic finish can be obtained with the application of one coat.

Description

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The present invention relates to a paint composition and a method of applying this paint composition to a concrete base.
Among the methods for applying paint to a concrete base, brush-coating and spray-gun methods are well-known. Before paint is applied to a concrete base with a brush, the surface of the base is pretreated usually by being polished by a grinder in order to remove unevenness or irregularities thereon and then the base is coated with mortar or putt~, further smoothed by sand paper, and treated with a sealer primer. Then an undercoat, second coat and final coat of paint are generally applied to the pretreated surface of the base with a brush. When a spray-gun is used, the surface of the base is cleaned and the unevenness and irregulari-ties are removed; pin holes are plugged, and a sealer primer is applied to the surface of the base before the under coat and final coat of paint are applied with the spray-gun.
However, the known methods of coating concrete involve a number of complicated processes, and much time and labour are re-quired for their practice. In particular, when hydraulic cement is sprayed with a spray-gun at a low temperature, efflorescence tends to take place, which cannot be avoided. Furthermore, considerable skill is required for spraying paint with a spray-gun, and there is usually a considerable amount of paint wasted. If, instead of expensive proper scaffolding, hanging-type scaffolding is construc-ted for paint-spraying of buildings, operational difficulties are increased and uneven application of paint tends to occur.
It has now been discovered, according to the present invention, that certain novel paint compositions which dry at ambient temperature, have short curing times, and do not crack or separate from the substrate after application, can be applied directly to concrete bases without subjecting the bases to any ~4~
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pretreatment. Further, it is possible to apply these paint com-positions in one step to give thick films thereof, which films only need to be finally coated with a protective material.
The surfaces which are coated with these paint composi-tions are suitable for indoor or outdoor use, and exhibit superior resistance to fading and weathering. Further, the coated surfaces have a glossy, ceramic appearance similar to that of ceramic tiles, and present no health hazard to humans coming into contact with them. Moreover, these coated surfaces can be repeatedly washed with water with virtually no variation in colour.
According to the present invention, there is provided a paint composition comprising a mixture of (a) Portland cement, (b) from 100 to 150 parts by weight of an aggregate, (c) from 1 to 3 parts by weight of calcium chloride, (d) from 0.4 to 2 parts by weight of naphthalene sulfonic acid formalin condensate, and (e) from 1 to 2 parts by weight of alkylcellulose, all of the parts be-ing based upon 100 parts of the Portland cement.
The paint composition of the present invention is usually prepared by adding to a mixture of Portland cement and an aggregate, in any order, 1-3 parts of calcium chloride, 0.4-2 parts of a naphthalene sulfonic acid formalin condensate, 1-2 parts of an alkyl cellulose, all of said parts being by weight per 100 parts by weight of the Portland cement. Further, it is possible to add to the composition at least one additive such as a dry pre-ventive agent, shrink prevention agent, efflorescent prevention agent, waterproofing agent, defoaming agent, coloring agent, and water. The resulting mixture is then processed into a paste.
The paste can be applied by means of a porous hand roller to the surface of a concrete basP in one step to give a mastic coating.
The expression "dry preventive agent" as used herein 1~

~ 47~36 means a hardener which serves mainly to retard evaporation of moisture in the paint composition.
The calcium chloride present in the composition serves to accelerate the curing of the paint composition.
Examples of the alkyl cellulose are either methyl cellu-lose or ethyl cellulose. The alkyl cellulose desirably has a high gel point, preferably above 90C.
It is preferable to use, as the naphthalene sulfonic acid formalin condensate, the sodium salt of ~-methyl naphthalene sulfonic acid formalin condensate.
Examples o additives which are introduced into the mix-ture are 2-5 parts of propylene glycol as a dry preventive agent, 0.5-10 parts of calcium sulfoaluminate (3CaO. 3A12O3. CaSO4) as a shrink prevention agent, 5-15 parts of zeolite as an efflorescence prevention agent, 0.1-5 parts of calcium stearate as a waterproof-ing agent, and 0.01-0.2 parts of tributyl phosphate as a defoaming agent, as well as a suitable amount of a ~olouring agent, all of the parts being by weight, based upon 100 parts by weight of the Portland cement.
It is possible, according to a preferred aspect of this invention, to add a synthetic rubber latex such as styrene-butadiene rubber or a vinyl resin emulsion such as a copolymer of acrylic acid or an ester thereof to the above-described paint composition, as this generally produces a film of more uniform quality and strengthens the bond between the finishing coat and the film formed of the paint composition of the present invention.
Further, if such a vinyl or acrylic acid or ester copolymer paint is applied as a finishing coat to the above-mentioned composition-coated base, the resulting layer provldes excellent protection as well as an aesthetically pleasing appearance.

~7~86 The method of the present invention differs from the ordinary roller painting method in which the paint composition which comprises finely divided white lime stone is applied with a brush roller to the surfaces of a porous base.
0 The method of the invention is also dif~erent from rollerapplication of a sandtextured coating, in which the aggregates mixed in the composition are apt to form agglomerates or fly about, causing extensive loss of the composition during application and giving rise to uneven finishes.
In order to achieve a satisfactory mastic coating using the prior compositions, it is usually required to apply the paint composition several times, which results in the production of thick coating layers which tend to crack during drying.
The method of the present invention overcomes the dis-advantages of the conventional methods. The present method can be easily practiced by using, for example, a porous hand-roller with which the paint composition of the invention is pressure-transfer-red to the surface of a base at the rate of from 1.3 to 2.4 kg/m2;
no special skill is required for this.
An example of a suitable porous hand roller for carry-ing out the present invention is one made of polyurethane foam produced according to U.S. Patent 3,171,820. This roller is made of reticulated foam which is obtained by hydrolysis of specially treated sponge followed by removal of the resulting film and has a 3-dimensional network structure. The U.S. Patent describes (at column 1) the structure of the foams as "novel reticulated poly-urethane foams". At column 2, lines 38-58, it is stated that the foams can be used in the fabrication of insulating materials but ~ there is no mention of the possibility of employing the foams for P 30 rollers for coating paints and the like. It has been found ~ha~
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,, rollers made of these foams having a 3~dimensional network struc-ture are particularly suited for putting the present invention into practice since they can absorb a substantial amount of paint.
In ~able 1, the work efficiency obtained by the method of the invention is compared with that of known methods of spray-ing a hydraulic cement and spraying a sand--textured paint composi-tion.
Table 1 Spraying Spreading Work Method Times of rate 2 rate 2 ef~iciency coatin~ (kg/m ) (kg/m ) (m /man-day) Method of pre-sent invention 1 1.3-1.8 1.2-1.7 60-70 Spraying of a hydraulic cement 2 1.2-1.3 0.8-1.0 60 Spraying of a sand-textured paint 2 0.7-1.7 0.5-1.2 ~5 Composition It has been observed that the surfaces o~ the spray finished concrete base usually become dirtier with time, whereas the surfaces of the concrete base treated by the method of the invention, are only slightly contaminated even after 2 years and 6 months; the small amount of contamination which does accumulate can be readily removed by washing with water.
Generally, the properties of the coating depend on where the coat is applied, for example to walls or to ceilings of a room, or indoors or outdoors.

It is particularly desirable for outdoor coatings to have good weather resistance, water resistance, adhesion, cleanliness, and rigidity. Indoor wall coatings should have good adhesion, water resistance and rigidity, and ceiling coatings should possess good adhesion and water resistance as well as an attractive appearance.

~47~86 he method of the present invention is particularly suitable for producing coatings for indoor or outdoor use. The films formed, after being allowed to stand ~or 28 days, have sur~
faces exhibiting a glassy uneven appearance similar to the surfaces of ceramic tiles, and such films are not only decorative but also cover any irregularities and pinholes on the surface of the ba$e.
The maximum thickness of the film prepared with the paint composition of the invention is usually from 2 to 3 mm, and its properties are given in Table 2.

Table 2 Item Results o the test Te~ting method or kind of etandard empIoyed.
1. Proce~sability Good A porou~ hand roller was employed in co-ducting the test.

2. Condition o~ Good Uni~ormity and ~tabi-coating film lity of the patterns pre~ented by the film and uniformity o~ its color.

- 3. Impac-t re~ist- No chænge at 1 kg JIS-A-5403 -ance (on 28 day- x 75 cm old film) 20 4. Adhe~ion More than 3 k ~cm2 An adhesion tester (Under normal kept at the Architect-condition) ural Re~earch Institute of the Ministry of Con-~truction wa~ employed in conducting the test.
5. Abra~ion test 95 mg/l,000 time~ Taber~ abra~ion test-(on 28 day- er. (Abraoer: H 22, old ~ilm) load: 250 g) 6. Wa3hability No change after JIS A 6909 being wa~hed 2,000 time~.
7. Degree of lu~t- More than 70 JIS-K 5400 er 8. Freeze thaw No change after 20 In accordance with ~tability cycles. ASTM C-290-61T
9. Water penet- Quantity of water JIS-A 6101 2 30ra-tion (on 28 penetrated: None Water pre~sure: 0.1 k~/cm day-old fil~) 10. Accelerated No ehange after IrIadiation by a weathering 1,000 hour~ weathermeter ;~ ~

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The invention is further illustrated by the following examples. Parts and percentages are by weight.
Example 1.
65 parts of water were added to 100 parts of a paint composition consisting of the ingredients stated below in Table 3, and the resultant mixture was kneaded into a pa,ste, which was then applied at a rate of 1.8 kg/m2 to surfaces of a 315 m2 indoor concrete wall of a ply-wood form. After the lapse of 2~ hours (tem-perature: 20C, relative humidi~y: 65%), a 25~ toluol solution of an acrylic ester copolymer was applied at the rate of 0.45 kg/cm2 to the film of the so-prepared paint composition. A coating having a glassy uneven finish resulted similar to the finish of ceramic tiles, which covered the irregularities of 2-3 mm and pinholes on the surface of the base. No cracking or peeling off of the covering paint was observed. The work efficiency was 65 m2/man-day. The adhesion of the film to the base was measured at 10 kg/cm2 under normal conditions after the film had been allowed to stand for 28 days. The film was 3.0 mm thick and not permeable to water.

~7~86 Table 3 Inyredients of the ~aint composition of Example 1 Item Kind ~ by weight Cement Hydraulic white Portla~d cement 100 Aggregate Silica sand (100-200 mesh)100 Pigment Anatase titanium dioxide 10 Zeolite (efflorescence preventive 10 agent) Calcium chloride 3.0 Naphthalene sulfonic acid formalin 1.2 condensate*
Additives Calcium stearate 0.5 Calcium sulfoaluminate (antishrink- 1.0 ing agent) - Methylcellulose (4000cp)~* 1.0 Tributyl phosphate 0.1 Proplyene glycol 2.0 * Tradename: Nopcosant (Nopco Chemical).
** Tradename; ~ethocel (Dow Chemical).

The viscosity of the methylcellulose in Tables 3 and 4 was measured as a 2% aqueous solution at 20C.

~3 Example 2 To 100 parts o~ a paint composition consisting of the ingredients stated below in Table 4 were added 70 parts of water and 20 parts of 46% acrylic ester copolymer emulsion. The mixture was kneaded into a paste. The paste was applied at a rate of 2.0 kg/m2 to a 101 m2 outdoor concrete wall of a metal form which had not been pretreated. After the lapse of 24 hours, (temperature:
20C, relative humidity: 65%), white enamel (solid content: 40%) in a toluol solution of an acrylic ester copolymer w~s applied to the film, prepared of the paint composition, at the rate of 0.4 kg/m2. A glassy uneven finish resulted similar to that of ceramic tiles, which covered the pinholes on the surface of the concrete base. No cracking or peeling off of the coating paint was observed. The worlc efEiciency was 70 m2/man-day. The film of the so-prepared paint composition possessed properties similar to those shown in Example 1. The addition of the polymer emulsion to the paint composition helped to produce a film of uniform quality and to improve the adhesion of the film to the finishing material.

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16)471~6 Table 4 Ingredients of the paint composition of Example 2 . . .
Item Kind ~ by weight i Cement Hydraulic white Portland cement 100 .. . . _ .
Aggregate Silica sand (100-200 mesh) 150 Pigment Anatase titanium dioxide 10 -Zeolite 12 Calcium chloride 2.0 Naphthalene sulfonic acid formalin 1.5 condensate*
Calcium stearate 0.5 Additives Calcium sulfoaluminate 1.2 Methylcellulose (4000 cp)** 1.5 Tributyl phosphate 0.1 Propylene glycol 4.0 * Tradename: Nopcosant (Nopco Chemical).
** Tradename: Methocel (Dow Chemical).

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Claims (16)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A paint composition comprising a mixture of (a) Portland cement, (b) from 100 to 150 parts by weight of an aggre-gate, (c) from 1 to 3 parts by weight of calcium chloride, (d) from 0.4 to 2 parts by weight of naphthalene sulfonic acid forma-lin condensate, and (e) from 1 to 2 parts by weight of alkylcellu-lose, all of said parts being based upon 100 parts of said Portland cement.

2. A composition according to claim 1, also comprising per 100 parts of said Portland cement, from 2 to 5 parts by weight of propylene glycol.

3. A composition according to claim 1, also comprising, per 100 parts of said Portland cement, from 0.5 to 10 parts by weight of calcium sulfoaluminate.

4. A composition according to claim 1, 2 or 3, also comprising per 100 parts of said Portland cement, from 5 to 15 parts by weight of zeolite.

5. A composition according to claim 1, 2 or 3, also comprising, per 100 parts of said Portland cement, 0.1 to 5 parts by weight of calcium stearate.

6. A composition according to claim 1, 2 or 3, also comprising per 100 parts of said Portland cement, from 0.01 to 0.2 parts by weight of tributyl phosphate.

7. A composition according to claim 1, 2 or 3, wherein the aggregate is silica sand.

8. A composition according to claim 1, 2 or 3, wherein the alkyl cellulose is methyl cellulose.

9. A composition according to claim 1, 2 or 3, com-prising also a pigment.

10. A composition according to claim 1, comprising water and in the form of a paste.

11. A composition according to claim 10, comprising also a styrene-butadiene rubber latex.

12. A composition according to claim 10, comprising also a vinyl resin emulsion.

13. A method of coating a base, which method comprises applying a paste according to claim 10 with a porous roller to said base, to form a film thereon.

14. A method according to claim 13, wherein the base is of concrete.

15. A method according to claim 13, wherein the paste is according to claim 11 or 12.

16. A method according to claim 13 or 14, comprising also the step of coating a vinyl or acrylic acid or ester copoly-mer paint onto the film.