JP2001072918A - Water-based waterproof coating agent and waterproof coated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating agent capable of forming a coated film excellent in water resistance, weatherability, adhesion, antifoulancy and elongation at a low temperature and tack-free by employing an emulsion comprising two kinds of polymers each having a specific Tg obtained by a two-stage polymerization. SOLUTION: In a first polymerization step, a monomer mixture comprising 30-94.8 wt.% of an ethylenically unsaturated monomer (A), 0.1-10 wt.% of an ethylenically unsaturated carboxylic acid (B) and 0.1-10 wt.% of a hydroxyl group-containing ethylenically unsaturated monomer (C), the monomer weight being based on the total weight of monomers employed in both steps, is subjected to emulsion polymerization using a water-soluble radical polymerization initiator in the presence of a surfactant in an aqueous medium. In a second polymerization step, 1-10 wt.% of the monomer A and 0.1-4 wt.% of the monomer B are subjected to emulsion polymerization in the same manner as in the first step to give an emulsion comprising 50-95 wt.% of a polymer A having a Tg of -30 to -5 deg.C and 5-50 wt.% of a polymer B having a Tg of 0-80 deg.C. This emulsion is used as the subject coating agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based waterproof coating agent and a waterproof coating film obtained by coating the same, and more particularly, to a coating film having excellent water resistance, weather resistance and stain resistance, and having a low temperature. The present invention relates to a waterproof coating agent which is excellent in elongation and forms a waterproof coating film having no tack, and a waterproof coating film obtained by coating the same.

[0002]

2. Description of the Related Art It is necessary to apply an appropriate waterproof treatment to the surface of a building such as a roof or a wall surface to prevent water permeation.
Among the waterproofing methods, in the case of waterproofing with a coating film, there are two types: a type using a solvent type resin such as polyurethane and epoxy resin; and a type using an emulsion such as an acrylic resin and an ethylene-vinyl acetate copolymer resin or a synthetic rubber latex. is there.

[0003] In recent years, from the viewpoints of environmental protection and safety and health, there has been a strong demand for non-pollution and safety and health of paints, and the use of water-based paints instead of solvent-based paints is expanding. Emulsions of water-based paints used as film-forming materials include acrylic emulsions, vinyl acetate-based emulsions, ethylene-vinyl acetate-based emulsions, and synthetic rubber latex. Vinyl acetate-based emulsions are resistant to water and alkali. Ethylene-vinyl acetate emulsions have some drawbacks in that they have significantly improved the drawbacks of vinyl acetate emulsions, but are inferior to acrylic emulsions in terms of weather resistance and water resistance.
Synthetic rubber latex also has a disadvantage in terms of weather resistance. It can be said that an acrylic emulsion shows the best performance as an emulsion used in a waterproofing composition comprehensively.

In recent years, better weather resistance, stain resistance,
A waterproof coating material that satisfies the maintenance of the flexibility of a coating film in a cold region or winter and the prevention of stickiness of the coating film in summer (hereinafter referred to as “tack-free”) is regarded as important.
Naturally, in order to cope with this, an inorganic filler and a short fiber are blended with an acrylic emulsion having a low Tg value,
A method has been proposed for achieving both low-temperature flexibility and tack-free coating film surface (Japanese Patent Laid-Open No. 52-136229).

[0005]

However, the long-term weather resistance desired in recent years is insufficient. Further, an acrylic silicone-based graft copolymer resin obtained by copolymerizing an organopolysiloxane having a reactive vinyl group has been proposed (JP-A-2-150475). Regarding this, although the performance is sufficient, it is necessary to finely disperse the organopolysiloxane having a reactive vinyl group and the monomers in advance during the production of the emulsion, so that it is difficult to produce with an ordinary emulsifying apparatus. is there. In addition, since it is expensive, it is economically disadvantageous and lacks versatility.

As described above, the water-based waterproof coating material has excellent water resistance, weather resistance, stain resistance, and low-temperature elongation.
Inexpensive and versatile materials such as tack-free and acrylic silicone-based graft copolymer resins have not yet been obtained. The present invention has water resistance, weather resistance, adhesion,
An object of the present invention is to provide a water-based waterproof coating agent which is excellent in stain resistance and low-temperature elongation and which forms a tack-free coating film.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies on a method for improving the above-mentioned drawbacks without impairing the various characteristics of the conventional aqueous emulsion.
In a two-stage polymerization step comprising a polymerization step and a second polymerization step, in the first polymerization step, the ethylenically unsaturated monomer (a),
A monomer mixture comprising an ethylenically unsaturated carboxylic acid (b) and a hydroxyl group-containing ethylenically unsaturated monomer (c) is emulsified with a water-soluble radical polymerization initiator in an aqueous medium in the presence of a surfactant. And then, in a second polymerization step, the monomers (a) and (b) are emulsion-copolymerized in the same manner as in the first polymerization step to obtain an emulsion having a specific ratio of polymer A and polymer B having a specific Tg value. The inventors have found that a coating film obtained from a water-based waterproof coating agent is excellent in water resistance, weather resistance, stain resistance, low-temperature elongation and tack-free, and completed the present invention.

That is, in the first step of the present invention, in a two-stage polymerization step comprising a first polymerization step and a second polymerization step, the total amount of the monomers used in the two-stage polymerization step is compared with the amount of ethylenic acid in the first polymerization step. 30 to 94.8% by weight of an unsaturated monomer (a), 0.1 to 10% by weight of an ethylenically unsaturated carboxylic acid (b) and 0.1 of a hydroxyl group-containing ethylenically unsaturated monomer (c) 0.1
-10% by weight of a monomer mixture is emulsion-copolymerized with a water-soluble radical polymerization initiator (e) in an aqueous medium in the presence of a surfactant (d), and then in a second polymerization step, 1 to 10% by weight of monomer (a) and 0.1 of monomer (b)
Polymer A having a Tg value of −30 ° C. to −5 ° C., which is obtained by emulsion copolymerization of
0-95% by weight (component A), Tg value of 0 ° C to 80 ° C
And a water-based waterproof coating agent comprising an emulsion containing 5 to 50% by weight (component B) of Polymer B. A second aspect of the present invention relates to a waterproof coating film formed by applying the first water-based waterproof coating agent of the present invention. Further, the third aspect of the present invention
Has a water whitening resistance of 4 points or more and a water permeability of 0.2 ml / m ²
24 hours or less, 90% gloss retention due to accelerated weather resistance
As described above, the elongation at −10 is 80% or more, the value of surface tack by a tack tester is 0.2 g or less, and the stain resistance is 4
The present invention relates to a second waterproof coating film according to the present invention, which has the following points. Less than,
The present invention will be described in detail.

In the present invention, the Tg value (glass transition point) of the acrylic copolymer contained in the emulsion which is the main component is measured and calculated by the following method. T
The g value can be measured using a thermal analyzer such as a differential scanning calorimeter (DSC) or a thermomechanical analyzer (TMA). For example, when the Tg value of a homopolymer of a monomer is known. Can be obtained by the FOX equation shown below. 1 / Tg = W1 / Tg1 + W2 / Tg2 W1: weight fraction of monomer (1) W2: weight fraction of monomer (2) (W1 + W2 =
1) Tg1: Tg (K) of the homopolymer of the monomer (1) Tg2: Tg (K) of the homopolymer of the monomer (2) The Tg value in the examples and comparative examples in the present invention is calculated by the above formula. It is.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The water-based waterproof coating agent in the present invention is obtained by dispersing a polymer-based dispersoid in a dispersion medium containing water as a main component. (I) Production Method The emulsion polymerization method for producing the water-based waterproof coating agent of the present invention is not particularly limited, and can be produced, for example, by the following method. (A) A monomer dropping method in which a mixture of the following monomers (a), (b), and (c) capable of undergoing radical polymerization is dropped in the presence of water, an emulsifier, and an initiator. (B) A pre-emulsion method in which a mixture of the following monomers (a), (b) and (c) is emulsified in the presence of water and an emulsifier, and polymerization is carried out while dropping the mixture into a system containing an initiator. (C) water, emulsifier, initiator, monomers (a), (b),
A one-bath polymerization method in which radical polymerization is performed in the presence of all of the mixture (c). In addition, in the monomer dropping method and the pre-emulsion method, 1 to 50% by weight of the dropping amount, preferably 3 to
30% by weight can be added before the start of the polymerization. From the viewpoint of safety, the monomer dropping method and the pre-emulsion method are preferable, and among them, the pre-emulsion method is more preferable.

(II) Raw material and polymerization initiator (1) Raw material monomer (a) Ethylenically unsaturated monomer Representative examples of the monomer (a) include, for example, methyl acrylate, ethyl acrylate, propyl acrylate,
Butyl acrylate, hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate,
C1-C24 alkyl of (meth) acrylic acid such as lauryl methacrylate, stearyl methacrylate, or
Cycloalkyl ester; styrene, vinyltoluene,
Aromatic unsaturated monomers such as α-methylstyrene, N-vinylpyrrolidone and vinylpyridine; epoxy group-containing (meth) acrylates such as glycidyl acrylate and glycidyl methacrylate; 1-methyl 2-pyrrolidone acrylate, acrylic acid 1 C1-C24 alkyl esters containing a pyrrole ring of (meth) acrylic acid, such as -ethyl 2-pyrrolidone, 1-methyl 2-pyrrolidone methacrylate, 1-ethyl 2-pyrrolidone methacrylate; 1-methyl 2-acrylate Oxazolidone, 1-ethyl acrylate 2-oxazolidone, 1-methacrylic acid
Methyl 2-oxazolidone, 1-ethyl methacrylate 2
-Oxazolidone, oxazole ring-containing C1 to C24 alkyl esters of (meth) acrylic acid; acrylamide, N-methylolacrylamide, N-butoxymethylacrylamide and the like. One or a combination of two or more of these may be used.

(B) Ethylenically unsaturated carboxylic acid Representative examples of the monomer (b) include acrylic acid, methacrylic acid, maleic acid and crotonic acid. One or a combination of two or more of these may be used.

(C) Hydroxyl-containing ethylenically unsaturated monomer Representative examples of the monomer (c) include C2 of (meth) acrylic acid such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate.
And C8 hydroxyalkyl esters and (meth) acrylates having a polyoxyethylene chain. One or a combination of two or more of these may be used.

(2) Amount of raw material monomer used Each Tg of component A and component B in emulsion particles
The amount of the monomers (a), (b) and (c) to be included in the components A and B are as follows with respect to the total amount of the resin, that is, the total amount of the monomers used in all the steps. Used in the range. The Tg value of the A component is
The temperature is from -30C to -5C, preferably from -20C to -10C. When the Tg value is lower than −30 ° C., the coating tends to be sticky, and when the Tg value is higher than −5 ° C., the elongation of the film at low temperatures is not maintained. The Tg value of the component B is 0 ° C.
To 80 ° C, preferably 5 ° C to 30 ° C. Tg value is 0
If the temperature is lower than ℃, the coating film tends to be sticky, and T
When the g value is higher than 80 ° C., the elongation of the film at a low temperature is not maintained.

The use range of the monomer (a) constituting the component A is 30 to 94.8% by weight, preferably 38 to 94% by weight, and the monomer (b) is 0.1 to 10% by weight, preferably Is 0.5 to 5% by weight, and the monomer (c) is
It is in the range of 0.1 to 10% by weight, preferably 0.5 to 7% by weight.

If the amount of the monomer (a) used in the component A is less than 30% by weight, the elongation of the film at low temperatures cannot be maintained. On the other hand, when the content exceeds 94.8% by weight, the polymerization stability becomes poor and a stable emulsion cannot be obtained. If the amount of the monomer (b) is less than 0.1% by weight, the polymerization stability will be poor and a stable emulsion cannot be obtained.
If it exceeds 10% by weight, the alkali resistance of the film is reduced. When the amount of the monomer (c) is less than 0.1% by weight, the hydrophilicity of the film surface is reduced, and the stain resistance tends to be deteriorated. If it exceeds 10% by weight, the water resistance of the film is reduced.

If the amount of the monomer (a) used in the component B is less than 1% by weight, the tack-free film at high temperatures cannot be maintained. On the other hand, when the content exceeds 49.9% by weight, the polymerization stability becomes poor, and a stable emulsion cannot be obtained. If the amount of the monomer (b) is less than 0.1% by weight,
The polymerization stability becomes poor, and a stable emulsion cannot be obtained. On the other hand, if it exceeds 4% by weight, the alkali resistance of the film decreases.

The ratio of the component A to the component B is 50/50 to 9
It is in the range of 5/5, preferably 70/30 to 90/10. If the ratio of the component A / B is less than 50/50, the elongation of the coating film at low temperatures is not more than 80%, which is not preferable. If it exceeds 95/5, the coating becomes too sticky and stain resistant. Is undesirably reduced.

(3) Polymerization initiator (d) Emulsifier Examples of the emulsifier used in the present invention include anionic surfactants, nonionic surfactants, and amphoteric surfactants. Examples of the anionic surfactant include a fatty acid ester salt of a higher alcohol, an alkylbenzene sulfonate, and an aliphatic sulfonate. Examples of the nonionic surfactant include an alkyl ester type, an alkyl ether type and an alkyl phenyl ether type of polyethylene glycol. Examples of the amphoteric surfactant include a carboxylate, a sulfonate, and a sulfate as an anion portion, and an amine salt and a quaternary ammonium salt as a cation portion. Also,
A reactive emulsifier in which a polymerizable functional group is introduced into the above-mentioned surfactant can also be used. These are used in an amount of 0.2 to 5% by weight, preferably 0.5 to 3% by weight, based on the resin.
% By weight.

(E) Radical Polymerization Initiator The radical polymerization initiator in the present invention is one that undergoes radical decomposition by heat or a reducing substance to cause addition polymerization to a monomer. Can be used. Examples include potassium persulfate, sodium persulfate, ammonium persulfate (APS), hydrogen peroxide, t-
Butyl hydroperoxide, t-butyl peroxybenzoate, 2,2-azobisisobutyronitrile,
There are 2,2-azobis (2-diaminopropane) hydrochloride and the like, and a water-soluble one is particularly preferable. The used amount is added so as to be 0.05 to 2% by weight, preferably 0.1 to 0.5% by weight based on the produced resin. When it is desired to accelerate the polymerization rate and perform the polymerization at a low temperature, a reducing agent such as sodium bisulfite, ferrous chloride, ascorbate, or Rongalit can be used in combination with the radical polymerization initiator. It is also possible to add a chain transfer agent such as dodecyl mercaptan for controlling the molecular weight.

The aqueous emulsion polymerized in the present invention is:
Shows stable dispersibility without neutralizing the carboxyl groups in the aqueous emulsion, but to maintain long-term dispersibility, for example, ammonia, sodium hydroxide, potassium hydroxide,
It is preferable to adjust the pH in the range of 6 to 10 using amines. (4) Other additives In addition, the aqueous emulsion of the present invention contains components usually added to water-based paints, such as a thickener, an antifoaming agent, a pigment,
Dispersants, dyes, preservatives and the like may be added. According to the present invention, it is possible to obtain a coating film having excellent water resistance, weather resistance, adhesiveness, stain resistance, low-temperature elongation and low tackiness which could not be obtained with a waterproof coating agent in a water emulsion. Can be. Furthermore, it can be manufactured industrially easily and inexpensively with ordinary manufacturing equipment and manufacturing conditions.

[0022]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. In the examples, parts and percentages are by weight.

Example 1 First Polymerization Step (Synthesis of Polymer A Component) As the first step, 10.17 parts of deionized water and an anionic surfactant (Aqualon HS-1025: Daiichi Kogyo Seiyaku Co., Ltd.) (D1) 2.07 parts, methyl methacrylate (a1) 18.39 parts, cyclohexyl methacrylate (a2) 3.40 parts, 2-ethylhexyl acrylate (a3) 26.47 parts, methacrylic acid (b1) ) 0.24
Part, 2-hydroxyethyl methacrylate (c1) 0.4
Nine parts were added using a stirrer at about 900 to 1500 revolutions to obtain a pre-emulsion.

Next, as a second step, 26.31 parts of deionized water and Aqualon HS were placed in a 2-liter four-necked flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer.
-1025 (d1) 0.05 part and a part of the pre-emulsion obtained in the first stage were charged and 70 ° C. under a nitrogen gas stream.
, And APS was added thereto as a polymerization initiator (e1), and the remaining pre-emulsion was added dropwise over 4 hours. At this time, the polymerization temperature was maintained in the range of 73 to 77 ° C., and was maintained at the same temperature range after the completion of the dropwise addition for 1 hour.
After cooling to 0 ° C., the first polymerization step (A component) was completed.

Second Polymerization Step (Synthesis of Polymer B Component) Next, the polymerization liquid of the polymer A component obtained in the first polymerization step is further kept in an internal temperature of 50 ° C., and then deionized water is added to the polymerization liquid. 13 parts were added and then methyl methacrylate (a
1) 3.03 parts, 2.10 parts of butyl acrylate (a4),
And a mixture of 0.27 parts of methacrylic acid (b1) was added dropwise over 1 hour. After completion of the dropwise addition, APS was added as a polymerization initiator (e2) to polymerize the monomer constituting the component B, and maintained at 50 ° C for 1 hour, and then cooled to room temperature.
The mixture was filtered with a 200 mesh filter cloth. The dry weight of the filtered agglomerate was very low, 0.002% of the total monomer. The resulting aqueous emulsion had a nonvolatile content of 5
6.5%, the average particle size of the emulsion was 190 nm.

As described above, in the first embodiment, the ratio of the A component / B component is 90/10, the Tg value is a calculated value, and the A component:
The temperature was adjusted to 16.7 ° C and the B component: 23.0 ° C.

(Example 2) Acrylic acid 2 in component A
-Ethylhexyl (a3) with butyl acrylate (a4)
Was performed in the same manner as in Example 1 except that the above was replaced with The dry weight of the filtered agglomerate was very low, 0.003% of the total monomer. The obtained aqueous emulsion had a nonvolatile content of 55.5%, and the average particle size of the emulsion was 200 nm.

As described above, in the second embodiment, the ratio of the component A / B is 90/10, the Tg value is a calculated value, and the component A:-
The temperature was adjusted to 14.0 ° C and the B component: 23.0 ° C.

(Example 3) In Example 3, the ratio of the A component / B component was 72/28, and the Tg value was a calculated value. The A component was -15.4 ° C and the B component was 23.0 ° C. I made it. Otherwise, the same operation as in Example 1 was performed.
The dry weight of the filtered agglomerate is 0.0
It was very slight at 02%. The obtained aqueous emulsion had a nonvolatile content of 55.5%, and the average particle size of the emulsion was 200 nm.

Comparative Example 1 First Polymerization Step (Synthesis of Polymer A Component) As the first step, 10.17 parts of deionized water and an anionic surfactant (Aqualon HS-1025: Daiichi Kogyo Seiyaku Co., Ltd.) (D1) 2.07 parts, methyl methacrylate (a1) 21.42 parts, cyclohexyl methacrylate (a2) 3.40 parts, 2-ethylhexyl acrylate (a3) 26.47 parts, butyl acrylate ( a4) 2.1
0 parts, 0.51 part of methacrylic acid (b1) and 0.49 part of 2-hydroxyethyl methacrylate (c1) were added at about 900 to 1500 rpm using a stirrer to obtain a pre-emulsion.

Next, as a second stage, 26.31 parts of deionized water, AQUALON HS were placed in a 2-liter four-necked flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer.
0.05 parts of -1025, sodium bicarbonate (sodium bicarbonate)
(D1) 0.09 part of the pre-emulsion obtained in the first stage was charged and heated to 70 ° C. under a nitrogen gas stream, to which APS was added as a polymerization initiator (e1), and the remaining pre-emulsion was added. The emulsion was added dropwise over 4 hours. The polymerization temperature at this time is maintained in the range of 73 to 77 ° C., and after maintaining the same temperature range for 1 hour after the completion of the dropwise addition, the mixture is cooled to room temperature.
The mixture was filtered with a 200 mesh filter cloth. The dry weight of the filtered agglomerates was very low, 0.002% of the total monomer. The resulting aqueous emulsion had a nonvolatile content of 5
5.5%, the average particle size of the emulsion was 190 nm. As described above, in Comparative Example 1, the monomer used for the component B was mixed with the monomer for the component A, and a polymerization reaction was performed in one stage. The Tg value was a calculated value and was controlled to be -9.3 ° C.

Comparative Example 2 The composition of the component A was as follows: 30.00 parts of methyl methacrylate (a1), 3.40 parts of cyclohexyl methacrylate (a2), 14.87 parts of 2-ethylhexyl acrylate (a3), methacryl Acid (b1) 0.2
4 parts, 2-hydroxyethyl methacrylate (c1) 0.
49 parts, and the composition of the component B was butyl acrylate (a
4) 3.13 parts, methyl methacrylate (a1) 2.00
Parts and methacrylic acid (b1) 0.27 parts, except that the operation was the same as in Example 1. The dry weight of the filtered agglomerate was very low, 0.002% of the total monomer. The resulting aqueous emulsion had a nonvolatile content of 5
5.5%, the average particle size of the emulsion was 190 nm. As described above, in Comparative Example 2, the ratio of the A component / B component was 90/10, the Tg value was a calculated value, and the A component was 24.5.
° C, B component: -6.2 ° C.

(Comparative Example 3) In Comparative Example 3, the ratio of the A component / B component was 40/60, and the Tg value was a calculated value. The A component was -16.7 ° C and the B component was 23.0 ° C. I made it. Otherwise, the same operation as in Example 1 was performed.
In this case, a stable emulsion was not obtained. Table 1 shows the composition and properties of the emulsion monomers in each of the above Examples and Comparative Examples.

[0034]

[Table 1]

(Test for Evaluating Performance of Coating Film) Each aqueous emulsion obtained in Examples 1 to 3 and Comparative Examples 1 to 3 was
Non-volatile content: adjusted to about 40% by dilution to prepare a test emulsion. This is applied to a slate plate with a brush and dried at room temperature for 7 days to obtain a test piece. Slate board is J
An IS flexible board was used, and the coating amount of the emulsion was 150 g / m ² . Using the above test pieces, tests for water resistance, water permeability, weather resistance, stain resistance, strong elongation of the film, and surface tack of the film were performed. Table 2 shows the results.

(1) Water resistance test method (JIS K540)
The test piece was immersed in water for 7 days. Thereafter, the film is taken out from the water and the degree of whitening of the film is visually determined. The criteria are as follows. 5 points: no change in transparency, no swelling and no peeling. 4 points: Slightly blue and whitening is observed. No swelling, no peeling. 3 points: slight whitening is observed. Swelling in part,
Peeling is observed. 2 points: whitening is observed. In some parts, swelling and peeling are observed. 1 point: The entire surface is whitened, swollen, and peeled.

(2) Water permeability test method (JIS K540)
Pour water into the permeability tester installed on the test piece,
The amount of water absorbed by the slate plate was read on a scale to calculate the amount of water absorption. (Ml / m ² · 24 hr) (3) Accelerated weather resistance Using the test piece, a super UV tester was used for an acceleration test for 1000 hours to measure the gloss retention of the film.

(4) Stain resistance A contaminant prepared by mixing 10% of carbon black with white vaseline was rubbed on the test piece with a cloth of about 1 g with an even force for 10 reciprocations. 4
Cure for 1 week at 0 ° C. After curing, wipe off contaminants with a clean cloth, wash thoroughly with water and dry at room temperature. After drying, the state of the film was visually determined according to the following criteria. 5 points: No trace remains. 4 points: In some parts, traces are slightly observed. 3 points: Traces remain in part. 2 points: In some parts, traces are clearly left. 1 point: Traces are clearly left on the entire surface.

(5) Strength and Elongation of Film Each emulsion for test was placed on a glass plate with a thickness of 0.5 mm.
, Dried at room temperature for 7 days, and then peeled off to form a test piece with a 1 cm x 6 cm strip. Using the test piece, 20 ℃, -1
The elongation was measured at a temperature of 0 ° C.

(6) Surface tack The stickiness of the coating surface of the test piece was measured by PICMA.
It was evaluated in a constant temperature and humidity chamber by a tack tester (manufactured by Toyo Seiki Seisakusho). Evaluation conditions were as follows: test temperature: 20 ° C.
Tack force was evaluated (unit: g) with a humidity of 65%, a pressure bonding time on the surface of the test piece: 20 seconds, and a desorption speed from the surface of the test piece: 30 mm / min.

[0041]

[Table 2]

[0042]

According to the present invention, excellent water resistance, weather resistance, adhesion, stain resistance, and elongation at low temperatures, which have not been obtained with a waterproof coating agent using a water emulsion, have been obtained.
Further, a tack-free coating film can be obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) JB23 JC09 JC14 KA03 KA09 LA02 MA08 MA10 MA13 NA03 NA04 NA05 NA11 NA12 PB05

Claims (3)

[Claims] 1. A method comprising a first polymerization step and a second polymerization step.
In the first polymerization step, 30 to 94.8% by weight of the ethylenically unsaturated monomer (a) and 0 to 9% by weight of the ethylenically unsaturated carboxylic acid (b) are added to the total amount of the monomers used in the two-stage polymerization step. A monomer mixture consisting of 0.1 to 10% by weight and 0.1 to 10% by weight of a hydroxyl group-containing ethylenically unsaturated monomer (c) in an aqueous medium in the presence of a surfactant (d),
Emulsion copolymerization is carried out using a water-soluble radical polymerization initiator (e). Then, in a second polymerization step, 1 to 10% by weight of a monomer (a) and 0.1 to 4% by weight of a monomer (b) are first polymerized. Tg value obtained by emulsion copolymerization in the same manner as in the step is -30 ° C
A water-based waterproof coating agent comprising an emulsion containing 50 to 95% by weight (component A) of polymer A at a temperature of -5 ° C and 5 to 50% by weight (component B) of polymer B having a Tg value of 0 to 80 ° C. 2. A waterproof coating film formed by applying the water-based waterproof coating agent according to claim 1. 3. Water whitening resistance of 4 points or more and water permeability of 0.2
ml / m ² · 24 hr or less, gloss retention by accelerated weather resistance is 90% or more, elongation at −10 is 80% or more, surface tack value by a tack tester is 0.2 g or less, and stain resistance is 4 3. The waterproof coating film according to claim 2, which has a rating of not less than a point.