JPH0565427A - Cement-based coating composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition containing cement, inorganic fine powder, a dispersing agent and an emulsion polymer, having excellent substrate- protecting effect, adhesivity, weather resistance and chemical resistance and useful as a paint-protecting agent, etc. CONSTITUTION:The objective composition is produced by compounding (A) 100 pts.wt. of cement with (B) preferably 15-200 pts.wt. of inorganic fine powder such as silica and/or blast furnace stag (the weight-average particle diameter is preferably <=10mum), (C) preferably 0.1-3wt.% (in terms of solid) of a dispersing agent such as sulfonated melamine dispersing agent, (D) preferably 3-25wt.% (in terms of solid) of an emulsion polymer such as acrylic polymer (having particle diameter of preferably 0.05-1mum) and, as necessary, (E) preferably 0-20wt.% of fine aggregate. The cement/water ratio of the above composition is 20-45%.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel and useful cement-based aqueous coating composition. More specifically,
A cement-based aqueous solution which comprises cement, a specific fine-particle inorganic powder, a dispersant and an emulsion polymer, and, if necessary, fine aggregate and water as well, which is particularly excellent in substrate adhesion and durability. Coating composition.

[0002]

2. Description of the Related Art A coating agent containing a synthetic resin as a main binder is widely used for beauty and protection of a substrate.

However, a coating material containing a resin as a main binder has a deterioration of the coating film due to photo-deterioration of the resin itself due to long-term outdoor exposure, and thus requires repair within a relatively short period of time after construction. Not only that, the synthetic resin itself requires a large amount of energy in production, so that it is relatively expensive, and also from the viewpoint of energy saving, its use and usage amount are limited.

On the other hand, a cement-based coating agent containing cement as a main binder is inexpensive because it is a water-based coating agent and has the advantage of little photodegradation. Poor, and the coating film,
That is, the cement hardened product cannot be sufficiently dense, and the effect of protecting the base material such as water permeation resistance is inferior, so that it is inferior in practicality.

Regarding the improvement of the substrate adhesion, various so-called polymer cement-based coating agents, in which an emulsion polymer is used in combination, have been investigated, and the substrate adhesion is improved, but the coating film is sufficiently improved. Could not be dense, and the effect of protecting the substrate was still insufficient.

[0006]

Therefore, the inventors of the present invention have made diligent research in order to solve the various problems in the above-mentioned conventional technology and to solve the various drawbacks in the above-described conventional technology. In particular, it has various properties and performances such as water-absorption resistance and base material adhesion, as well as excellent properties as a paint protection agent for hardened cement and iron members.
Research and development of extremely useful coating compositions was conducted.

Therefore, the problem to be solved by the present invention is that the adhesiveness to the substrate is excellent and the coating film is dense,
It is an object of the present invention to provide a cement-based coating agent which is excellent in durability such as water permeation resistance, freeze-thaw resistance and chemical resistance, and excellent in substrate adhesion.

[0008]

Therefore, the present inventors have
Focusing on the problem to be solved by the invention as described above, as a result of extensive and intensive studies, by using a cement-based coating agent having a specific composition, a coating film, that is, a cement-based cured product, Precise and durable,
Moreover, it has been found that the substrate adhesion is also excellent, and here, the substrate adhesion is excellent, the coating film is dense, and the durability such as water permeation resistance, freeze-thaw resistance, and chemical resistance is high. Then, the present invention, which is a cement-based coating agent excellent in substrate adhesion, has been completed.

That is, the present invention provides (a) cement,
A hydraulic cement-based coating composition comprising (b) a fine-particle inorganic powder, (c) a dispersant (d) an emulsion polymer, and optionally (e) a fine aggregate and water. To do.

Here, cement forms a hydrated crystal with water and serves as a main binder of the composition of the present invention. Considering the curing characteristics, the long-term stability of the cured product, and the easy availability, etc. Then, the use of normal Portland cement, white Portland cement or early strength (super early strength) Portland cement is desirable.

The finely divided inorganic powder (b) is an essential component for filling the gaps in the hardened cement body which is the main binder of the composition of the present invention and making the coating film (hardened body) dense. It is desirable to use particles having a particle size of ½ or less, more preferably ⅕ or less, and therefore, a weight average particle size of 10 μm (μm) or less.

However, the finer the particles, the more theoretically the coating film (cured product) becomes denser, but it is difficult to disperse the coating film in the composition, and the composition necessary for coating is also difficult. The cement / water ratio tends to be high to obtain fluidity,
Not preferable.

From this point of view, it is not preferable to contain a large amount of components having a particle size of 1 μm or less. As the composition of the fine particle inorganic powder (b), a wide range of materials such as metals, metal oxides, silicates, and mixed sintered products thereof can be used, and one or two of these can be used. Used as a mixture of the above.

In particular, it is desirable to use the cement that contributes to the hydration reaction under the alkaline condition of the cement, and it is particularly desirable to use silica or blast furnace slag. Also,
The amount of the fine particle inorganic powder (b) used is appropriately in the range of 15 to 200 parts by weight, more preferably 20 to 100 parts by weight, based on 100 parts by weight of the cement (a).

Next, the above-mentioned dispersant (c),
This is the above-mentioned cement (a), fine particle inorganic powder (b)
It is used to improve the fluidity of the formulation while improving the dispersion in the formulation and keeping the cement / water ratio low.

However, the use of the one having high air entrainment is
It is not preferable because it is difficult to obtain a dense coating film (cured product). From such a viewpoint, it is preferable to use a so-called high-performance dispersant (water reducing agent) such as a sulfonated melamine type, a naphthalene sulfonic acid type or a polycarboxylic acid type, and these are used as one kind or a mixture of two or more kinds.

The amount of the dispersant (c) used is 0.1 to 100 parts by weight of cement (a) in terms of solid content.
A ratio of 3 parts by weight is preferable. If it is less than 0.1% by weight, the dispersion effect is insufficient, while if it exceeds 3% by weight, the effect is saturated.

Further, it is preferably used in the range of 0.5 to 2% by weight. The coating film (cured product) obtained here
From the viewpoint of increasing the strength, it is preferable to use a sulfonated melamine-based material, and conversely, from the viewpoint of reducing the change with time of the fluidity of the formulation and improving the pot life, the polycarboxylic acid Those of the system are preferred.

From this, the combined use of the sulfonated melamine type dispersant and the polycarboxylic acid type dispersant is particularly preferable. The above-mentioned emulsion polymer (d) is used for improving the durability of the composition of the present invention such as substrate adhesion, abrasion resistance and chemical resistance.

In general, the emulsion polymer (d) is
From the fine particle polymer having a particle size of 0.05 to 1 μm, the above-mentioned cement (a) and fine particle inorganic powder (b)
It is also used for filling finer voids of the hydration structure of and to make the resulting coating film more dense.

The amount of cement used is 1 of cement (a).
It is desirable that the solid content is 3 to 25% by weight with respect to 00 parts by weight. If the amount used is less than 3% by weight, the effect of addition is insufficient. On the other hand, if the amount used exceeds 25% by weight, not only the effect is saturated, but also the hardness as a cement hardened product It is not preferable because the characteristics are easily lost.

More preferably, it is used in the range of 4 to 20% by weight. For the emulsion polymer (d), it is preferable that the polymer has high alkali resistance, and for that reason, the polymer composition is preferably an acrylic polymer, an acrylic styrene polymer, or a styrene butadiene polymer.

Further, in general, the emulsion polymer contains an emulsifier, and since it is easy to entrain air during kneading of the compound,
It is preferable to use an antifoaming agent together. The amount used at that time is 0.1 with respect to the solid content of the emulsion polymer (d).
The range of 3 wt% is preferable.

The fine aggregate (e) may generally have a particle size larger than that of the cement (c) which does not contribute to hydration, and among them, only typical ones can be used. To give an example, it is an inorganic powder such as natural sand, silica sand, silica powder, ceramic powder or glass beads, which is necessary for adjusting the condition of the coated surface and relaxing the shrinkage of hardening of cement. Depending on the cement (a) 100
It is used in an amount of 200 parts by weight or less with respect to parts by weight.

Next, with respect to water, the above-mentioned dispersant (c)
And / or if the emulsion polymer (d) is a liquid containing water, the ratio of cement / water is 0.2 to 0.02 including the amount of water contained in each of the aforementioned components. 45, that is, in the range of 20 to 45% by weight.

If it is less than 20%, the hydration of the cement is insufficient, and the strength of the resulting coating film (cured product) cannot be sufficiently expressed. On the other hand, if it exceeds 45%, In any case, since the strength cannot be developed due to the bleeding of water, either case is not preferable.

Further, when coloring of the coating film is required,
Various coloring pigments can be used, and in that case, the amount used is 100 parts by weight of cement (a),
The amount of 30% by weight or less is sufficient, and as the type, it is desirable to mainly use an inorganic pigment in consideration of fading of the pigment.

When it is necessary to prevent cracks due to shrinkage in the process of drying and curing the cement-based coating composition of the present invention, it is desirable to add a shrinkage preventive agent or a fiber reinforcing agent. As the agent, it is particularly desirable to use a gypsum-based agent having early-strength property. The amount of the agent used is 100 parts by weight of the cement (a).
Within the range of 0.2 to 10% by weight, more preferably,
A range of 0.2 to 5% by weight is suitable.

Further, only the representative examples of the above-mentioned fiber reinforcing agents are exemplified, and polyvinyl alcohol fibers, glass fibers, carbon fibers, asbestos fibers, metal fibers, cellulose fibers, polyimide fibers or nylon fibers can be used. As described above, various kinds of organic or inorganic fibers are used, and as one kind or a mixture of two or more kinds thereof, 0.05 to 100 parts by weight of cement (a) is used.
It is preferably used in the range of 3% by weight.

The composition of the present invention may further contain known and commonly used additives such as rust preventives, thickeners or surfactants and various solvents, if necessary. Also, in order to impart various functions such as elasticity and weight reduction, and reflection or absorption of electromagnetic waves, in addition to giving aesthetics and luminosity, natural stone particles, glass beads, rubber chips or expanded polystyrene beads, permuculite, etc. If desired, granular additives such as organic or inorganic lightweight aggregates, various metals and metal oxides, and sintered products thereof can also be used.

As a form of the composition before kneading, it is of course possible to use a powdered dispersant, a powdered emulsion polymer or the like to combine the powder mixture and water. In use, it is necessary to thoroughly knead and disperse the materials after they have been prepared.

The coating method is not particularly limited, but if only representative ones are exemplified,
Air spray (gun), airless spray, brush, trowel, roller, roll coater, shower ring, dipping or pouring (self-leveling), etc.

The film thickness of the coating film is also not particularly limited, but in order to fully exhibit the characteristics of the composition of the present invention, the dry film thickness is on average 0 depending on the use, purpose and object to be coated. 1-5
A range of about mm is suitable.

The drying method is not particularly limited, and may be normal drying (air-drying curing), heating or forced drying. Furthermore, in order to accelerate the hardening of cement, steam curing or autoclave curing may be used.

The applications of the thus obtained cement-based coating composition of the present invention are all applicable to synthetic resin-based paints, and there is no particular limitation, but preferred applications among them. For example, if only representative examples are given, surface protection of cement concrete frame (structure), floor / flat roof (planar part), molded body, etc., and calcium silicate board , Wood cement board, cement asbestos board, surface protection of various wall materials and roofing materials.

Further, it is also possible to utilize as a rust preventive coating agent for various iron members by utilizing the rust preventive effect due to the alkalinity of cement. In addition, it goes without saying that a paint containing a synthetic resin as a main binder may be applied over the coating film of the composition of the present invention.

[0037]

EXAMPLES Next, the present invention will be described with reference to Examples and Comparative Examples.
Although it will be described more specifically, all are based on weight unless otherwise specified.

[Blending] The powder materials described below are dry-blended in advance, and a liquid material such as an emulsion polymer, water, a dispersant or an antifoaming agent is added thereto, and the mixture is sufficiently mixed with a homodisper (high speed stirrer). I kneaded it.

The cement / water ratio was adjusted so that the formulation viscosity was a Stormer viscosity of 90 ± 15 KU. The composition is shown in Table 1.

[Application Test] The above-mentioned composition was applied to the following base material so that the dry film thickness was 1 ± 0.1 mm, and 2
After drying for 14 days at 0 ° C. and 65% RH, the parts other than the coated surface were sealed with an acrylic urethane sealing agent and subjected to various performance evaluation tests.

The results are summarized in the second and third.
Shown in the table.

Base material: A: Flexible board (thickness 3 mm, Nozawa Slate Co., Ltd. product) B: Untreated polished mild steel plate (Japan Test Panel Co., Ltd. product)

[Test method] (1) Water absorption resistance: The substrate is completely submerged in water for 24 hours.
Calculated from the weight change over time. (2) Water permeation resistance: A glass tube with a diameter of 20 mm is erected on the coated surface, the circumference is sealed, and water is put in the tube up to a height of 10 cm. Measured by height. (3) Acid resistance ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………. (4) Abrasion resistance: A taper abrasion tester (using an H22 abrasion wheel, a load of 500 g, 100 revolutions) was used to measure the abrasion loss after the test. (5) Adhesion to substrate: Measured with a Tensilon tester by attaching an attachment of 4 x 4 cm. (6) Freeze-thaw resistance: Submerge the whole substrate in water, -2
This was regarded as one cycle through a continuous process of 0 ° C. for 4 hours and then 40 ° C. for 4 hours, and the state after the 300 cycle test was visually judged. (7) Anticorrosion property ………… 500 with a salt spray tester
Visually judge the condition after the test over time. (8) Accelerated weather resistance: Visually judge the condition after 2,000 hours of test with a sunshine weather meter.

[Compounding Material] Ordinary Portland Cement; Product of Osaka Cement Co., Ltd. White Portland Cement; Product of Onoda Cement Co., Ltd. Early Strength Portland Cement; Same as above; Fine Inorganic Powder; Made fine blast furnace slag, average particle size = 4μ
m] Same as above; “Fine Cerament 20A” (same as above, average particle size = 6 μm) Dispersant: “SMF-35AG” [Nissan Chemical Co., Ltd. sulfonated melamine dispersant, solid content = 35
%] Same as above; "Watersol PC-56"
[Polycarboxylic acid-based dispersant manufactured by Dainippon Ink and Chemicals, Inc., solid content = 34%] Same as above; "Mighty 150" [Naphthalenesulfonic acid-based dispersant manufactured by Kao Corporation, solid content = 41%] Emulsion polymer; "Boncoat 550" [acrylic emulsion manufactured by Dainippon Ink and Chemicals, Inc., solid content = 40%) Fine aggregate; No. 8 silica sand defoamer; "Nopco 8034L" [San Nopco product] ] Shrinkage preventive agent; "PALACE" [Gypsum-based shrinkage inhibitor manufactured by Showa Ogyo Co., Ltd.] Fiber reinforcing agent; "Donacarb" [Carbon short fiber manufactured by Dainippon Ink and Chemicals, Inc.] Pigment; "Taipaque R-" 930 "[Titanium oxide manufactured by Ishihara Sangyo Co., Ltd.]

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

[Table 3]

[0048]

The composition of the present invention thus obtained has the hydrated cured product of cement (a) as the main binder, the voids thereof are filled with the fine-particle inorganic powder (b), and the voids are further emulsified. A coating film (cured product) having an extremely dense structure is obtained from the fact that it has a novel structure in which the polymer particles of the coalescence (d) are filled and further the molecules of the dispersant (c) are filled. It is a thing.

Therefore, the cement coating composition of the present invention is excellent in the effect of protecting the base material as a coating film, and, in addition, has good base material adhesion, weather resistance, chemical resistance and the like which polymer cement has. It also has an excellent coating effect.

Claims (10)

[Claims] 1. (a) Cement, (b) fine particle inorganic powder, (c) dispersant and (d) emulsion polymer, if necessary,
(E) characterized in that it also contains fine aggregate and water,
Cement-based coating composition. 2. To (a) 100 parts by weight of cement,
(B) 15 to 200% by weight of fine particle inorganic powder, (c) dispersant in solid content of 0.1 to 3% by weight, (d) emulsion polymer in solid content of 3 to 25% by weight, (e) ) Fine aggregate 0-20
A cement-based coating composition, characterized in that it is contained in an amount of 0% by weight, and the ratio of cement / water is 20 to 45%. 3. The cement-based coating composition according to claim 1, wherein the cement (a) is Portland cement. 4. The cement-based coating composition according to claim 1, wherein the fine particle inorganic powder (b) is silica and / or blast furnace slag. 5. The cement-based coating composition according to claim 1, wherein the dispersant (c) is a sulfonated melamine-based dispersant. 6. The cement-based coating composition according to claim 1, wherein the dispersant (c) is used in combination with a sulfonated melamine dispersant and a polycarboxylic acid dispersant. 7. The cement-based coating composition according to claim 1 or 2, wherein the emulsion polymer (d) is one of an acrylic type, an acrylic styrene type and a styrene butadiene type. 8. The cement-based coating composition according to claim 1, which comprises 0.2 to 10% by weight of a gypsum-based shrinkage inhibitor based on 100 parts by weight of the cement (a). 9. The cement-based coating composition according to claim 1, which comprises 0.05 to 3% by weight of a fiber reinforcing agent based on 100 parts by weight of the cement (a). 10. 100% by weight of the above-mentioned cement (a)
On the other hand, the cement-based coating composition according to claim 1 or 2, which comprises 30% by weight or less of a coloring pigment.