JPH0445169A - Paint composition of monolayer elastic emulsion - Google Patents

Abstract

PURPOSE:To obtain the subject composition having excellent elongation at a low temperature by using a polymeric emulsion as a binder comprising granules of a constant size and having glass transition temperatures of central layer, surface layer and intermediate layer of the granule in a specific range. CONSTITUTION:Polymerizable unsaturated monomer such as methyl (meth) acrylate is subjected to emulsion polymerization in the presence of water and emulsifier such as anionic surfactant to obtain a polymeric emulsion. The objective paint composition of monolayer elastic emulsion has excellent antifouling property and the emulsion granule has glass transition temperatures of from -60 deg.C to 10 deg.C (Ta) of central layer, 0-100 deg.C (Tb) of surface layer and (Tc) of intermediate layer in a range of Ta<=Tc<=Tb, and simultaneously Tb-Ta>=10 deg.C and granular diameters in a range of 0.3-3.0mu.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a coating composition containing a polymer emulsion as a binder, and more specifically, a coating composition that exhibits a considerable elongation rate at low temperatures and has excellent stain resistance. The present invention relates to a single layer elastic emulsion coating composition.

(Prior art) A coating composition using a polymer emulsion as a binder is
In recent years, the amount used has been increasing, and various high-level requirements for the composition have been increasing. For example, in single-layer elastic paints for construction, the film has a considerable elongation rate at low temperatures of around -10°C, and the film surface has low tackiness at room temperature, making it difficult for dirt such as dust to adhere ( Therefore, it is desired to develop a coating composition that satisfies such requirements.

Conventionally, in order to increase the elongation rate at low temperatures in paints that use a polymer emulsion as a binder, it has been done to use a polymer emulsion made of a monomer with a low glass transition temperature, or to add a large amount of plasticizer. However, in these cases, satisfactory quality in terms of stain resistance cannot be obtained, and in the end, it is difficult to simultaneously satisfy elongation rate at low temperatures and stain resistance depending on these methods. Ta.

One possible solution to this problem is to use a polymer emulsion consisting of particles with different compositions in the inner layer and the surface layer as a binder. The polymer emulsion can be synthesized by emulsion polymerization using a multi-step polymerization method, a power feed polymerization method (Japanese Patent Publication No. 51-46555), or the like. In this case, particles with a so-called multilayer structure are produced, but conventionally, in order to improve film-forming properties, the particles are supplied to the polymerization reaction system in such a way that the hard components are distributed in the inner layer and the soft components are distributed in the surface layer. The ingredients are being adjusted. However, the dry film obtained from a paint containing a polymer emulsion synthesized by this method as a binder does not have sufficient stain resistance because soft components appear on the surface. In addition, with the intention of obtaining a film with sufficient stain resistance, a polymer emulsion was synthesized by adjusting the components supplied to the reaction system so that the soft component was distributed in the inner layer and the hard component was distributed in the surface layer. However, the resulting polymer emulsion has a considerably high minimum film-forming temperature (MFT), and when used in a paint, a large amount of film-forming agent is required, making it difficult to create a paint that is satisfactory for practical use. That is difficult.

(Means for Solving the Problems) In view of the above points, the present inventors conducted intensive research and found that the inner layer is hard, the surface layer is hard, and the particle size is 0.3 to 3.0.
Polymer emulsions with so-called large particle diameters in the μm range have a lower MFT than those with normal particle diameters, and can solve film-forming problems.Also, paints using such emulsions as binders can be used at low temperatures. The growth rate of
They have also discovered that it is possible to obtain a film with excellent stain resistance at room temperature, and have completed the present invention.

That is, the present invention provides the glass transition temperature (T
a) is -60 to 10°C, and the glass transition temperature (T
b) is 0 to 100°C, the glass transition temperature (Tc) of the intermediate layer is in the range of Ta≦Tc≦Tb, and
Tb-Ta 210℃, particle size 0.3-3.0μ
A single-layer elastic emulsion coating composition comprising a polymer emulsion comprising particles in the range of m as a binder.

The polymer emulsion used in the present invention has a particle morphology in which the center layer is soft and the surface layer is hard.
The particle size is in the range of 0.3 to 3.0 μm, preferably in the range of 0.4 to 2.0 μm, and preferably in the range of 0.5 to 1.0 μm. More preferred.

Unless otherwise specified herein, "particle diameter" refers to what is measured by the following method. That is, Disk Centri manufactured by Joyce-Loeb1
The particle size distribution is measured using a fuge (M K-In type) particle size distribution analyzer, and the value of the particle size where the maximum peak appears in the obtained particle size distribution curve is defined as the "particle size" here. handle.

The following method can be used to create an emulsion with these properties. That is, it is produced by emulsion polymerization of a polymerizable unsaturated monomer in the presence of water and an emulsifier, from particles having a soft inner layer, a hard surface layer, and a particle size in the range of 0.3 to 3.0 μm. A method for producing an emulsion polymer comprising: (a) a polymerizable unsaturated monomer (A) supplied to the reaction system at the initial stage of the polymerization reaction;
a) is -60 to 10°C, and the polymerizable unsaturated monomer (B) supplied to the reaction system in the latter stage of the polymerization reaction is (B
) The glass transition temperature (Tb) of the polymer of The glass transition temperature (Tc) of is in the range of Ta≦Tc≦Tb,
and (b) regarding the supply of the emulsifier to the reaction system, the weight ratio of the emulsifier to the sum of the polymerizable unsaturated monomer and the polymer in the reaction system is This is a method for producing an emulsion polymer, characterized in that the polymerization reaction increases with time.

Here, to explain the glass transition temperature (Ta) of the polymer of the polymerizable unsaturated monomer (A) in more detail, the polymerizable unsaturated monomer (A) is from the monomer M1M2 M3... and the respective weight fractions are C, C2, C3...,
Homopolymer P1 of each monomer. P2. P3...
The glass transition temperature expressed in absolute temperature is T, respectively.
T2. T3..., Ta is expressed by equation (1).

The polymer of monomer (A) is specifically monomer MI.

It is a copolymer of M2, M3..., and Ta refers to the glass transition temperature of the copolymer. Ta is monomer (A
) is sometimes referred to as the glass transition temperature.

The same applies to the glass transition temperature (Tb) of the polymer of monomer (B) and the glass transition temperature ("rc) of the polymer of monomer (C).

In the method for producing the emulsion polymer, the above (a) and (
It is necessary to carry out both b), and the following methods can be mentioned as specific methods thereof.

That is, it stably emulsifies a polymerizable unsaturated monomer in the presence of water and an emulsifier to create a first monomer pre-emulsion, and emulsifies another polymerizable unsaturated monomer in the presence of water and an emulsifier. a second monomer pre-emulsion is stably emulsified in the presence of is an emulsion polymerization method in which a polymerizable unsaturated monomer is supplied from a second supply source to a first supply source, and at this time, the polymerizable unsaturated monomer is emulsion polymerized in the reaction system, (a) the first The polymerizable unsaturated monomer (
A), the glass transition temperature (Ta) of the polymer of (A) is -
60 to 10°C, and the polymerizable unsaturated monomer (B) in the monomer pre-emulsion supplied to the reaction system from the first supply source at the end of the polymerization reaction is the polymer of (B). The glass transition temperature (Tb) is 0 to 100°C, and
(b) The weight ratio of the emulsifier in the first monomer pre-emulsion to the polymerizable unsaturated it isomer in the first monomer pre-emulsion is the same as that in the second monomer pre-emulsion. The polymerizability of the monomer pre-emulsion supplied to the reaction system from the first source is lower than the polymerization ratio of the emulsifier in the same pre-emulsion to the unsaturated monomer (by (a) and (b) above). This is a method in which the composition of unsaturated monomers and emulsifiers is continuously changed over time of the polymerization reaction.

The emulsion polymer particles produced by the above method are characterized by having a multilayer structure and at the same time being larger in size than conventional particles. Conventional multilayer structure emulsion polymers generally have a particle diameter (d) of 0.3 μm or less, and the morphology of the film after film formation is usually a repetition of units of this size (≠d). On the other hand, since the emulsion polymer particles of the present invention have a large size, the repeat unit size of the morphology of the film after film formation becomes larger. As a result, unprecedented performance is expected. As a result of various tests, the present inventors have found that these emulsion polymers have the above-mentioned properties, which we believe is due to the film morphology in which the repeating units are large in size.

The polymerizable unsaturated intermediate used in the synthesis of the polymer emulsion is not particularly limited as long as it is commonly used in emulsion polymerization. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, lauryl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and 2-ethyl (meth)acrylate. -Hydroxyethyl, (meth)acrylic acid-2-
Various esters of acrylic acid or methacrylic acid such as hydroxypropyl, 3-4-2-hydroxypropyl (meth)acrylate or glycidyl (meth)acrylate: (meth)acrylamide or N-methylol (meth)acrylamide. various amides such as various carboxyl group-containing monomers such as nialic acid, methacrylic acid, maleic acid or fumaric acid; various dialkylamino group-containing monomers such as dimethylaminoethyl (meth)acrylate or diethylaminopropyl (meth)acrylate; Vinyl halides or vinylidene halides such as vinyl chloride vinylidene chloride or vinylidene fluoride; Various aromatic vinyl compounds such as styrene, α-methylstyrene or vinyltoluene; Various vinyl esters such as vinyl acetate or vinyl propionate. Various conjugated dienes such as butadiene or isoprene; Various polycarboxylic anhydride-containing monomers such as maleic anhydride or itaconic anhydride; Various aliphatic monoolefins such as ethylene, propylene or butene: Alternatively, various unsaturated nitriles such as acrylonitrile or methacrylonitrile may be mentioned. These materials can be used alone or in combination of two or more.

Further, the emulsifier used in the synthesis of the polymer emulsion of the present invention is not particularly limited as long as it is commonly used in emulsion polymerization, but specifically, anionic surfactants such as those shown below may be used. , nonionic surfactants, cationic surfactants and mixtures thereof can be used.

Examples of anionic surfactants include various fatty acid salts, higher alcohol sulfate ester salts, alkylbenzene sulfonates, dialkyl sulfosuccinates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, polyoxyethylene Examples include polyoxybrobylene glycol ether sulfate and polycarboxylic acid type polymeric surfactants. Examples of nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, sorbitan fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene/polyoxypropylene block copolymer, and the like. Further, examples of the cationic surfactant include alkylamine salts, quaternary ammonium salts, and the like.

The amount of these emulsifiers used is 0.01 to 10% by weight, preferably 0.1 to 5% by weight based on the total amount of polymerizable unsaturated monomers.
A range of % by weight is suitable.

The weight ratio of the emulsifier to the sum of the polymerizable unsaturated monomer and the polymer of the polymerizable unsaturated monomer in the reaction system must be increased as the reaction progresses. Therefore, the emulsifier is supplied so that this value increases more at the end of the reaction than at the beginning of the reaction, and the increase rate is suitably in the range of 1.5 to 500 times, preferably 2 to 100 times. .

In the synthesis of the polymer emulsion of the present invention, a polymerizable unsaturated monomer is emulsion polymerized in a reaction system, and at that time,
-II, a polymerization initiator is used. The polymerization initiator is not particularly limited as long as it is commonly used in emulsion polymerization, but specific examples include water-soluble inorganic peroxides such as hydrogen peroxide; potassium persulfate, ammonium persulfate, etc. Persulfates; organic peroxides such as cumene hydroperoxide, benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide; azo yarn starters such as azobisisobutyronitrile, azobiscyanovaleric acid These radical polymerization initiators can be used alone or in combination of two or more. The amount used is preferably 0.1 to 2% by weight based on the total amount of polymerizable unsaturated monomers. Note that redox polymerization may be carried out by using the above peroxide-based polymerization initiator together with a metal ion or a reducing agent as a polymerization initiator.

These initiators can be supplied by charging an aqueous solution or dispersion of the polymerization initiator into the reactor in advance, or by blending them into the polymerizable unsaturated monomer or monomer pre-emulsion. , a method in which an aqueous solution or aqueous dispersion of a polymerization initiator is fed into a reactor simultaneously with the polymerizable unsaturated monomer, or a combination of these methods can be used. Also,
After the supply of the polymerizable unsaturated monomer is completed, a portion of the polymerization initiator may be supplied to the reactor as an additional catalyst.

The amount of water used in the synthesis of the polymer emulsion of the present invention is 7 to 10 to 3 with respect to the total amount of polymerizable unsaturated monomers.
00% by weight, preferably in the range of 10 to 100% by weight.

In the synthesis of the polymer emulsion of the present invention, in addition to the above-mentioned polymerizable unsaturated monomers, emulsifiers, polymerization initiators, and water, chain transfer agents such as mercaptans, sodium bicarbonate, etc. Buffers such as sodium acetate may also be used. These additives can be supplied, for example, by charging them into the reactor in advance, or by mixing them into a polymerizable unsaturated monomer or polymer pre-emulsion and feeding it into the reactor. can be done.

In the synthesis of the polymer emulsion of the present invention, the feed rate of the polymerizable unsaturated monomer to the reaction system is determined by the monomers used,
It may be selected appropriately depending on the polymerization initiator, polymerization temperature, etc., but generally the total amount of polymerizable unsaturated monomers is 1 to 10
This is the speed at which the supply to the reaction system is completed over time. When supplying a polymerizable unsaturated monomer into the reaction system, a monomer pre-emulsion is created by stably emulsifying the polymerizable unsaturated monomer in the presence of water and an emulsifier, and this monomer pre-emulsion is An emulsion may be fed into the reaction system. A monomer pre-emulsion can be easily obtained, for example, by first mixing an emulsifier with water and then mixing the polymerizable unsaturated monomer with stirring.

The polymerization temperature of the reaction system is not particularly limited, but is usually 10 to 1
00°C, preferably 30 to 80°C.

The emulsion paint of the present invention is produced in the same manner as in the production of ordinary emulsion paints using the polymer emulsion specified above as a binder.

That is, pigments, fillers, aggregates, dispersants, wetting agents, thickeners and/or logic control agents, antifoaming agents,
Plasticizers, film-forming aids, organic solvents, preservatives, antifungal agents, pH regulators, rust preventives, etc. are selected and combined according to their respective purposes, and are made into paints using normal methods.

(Effects of the Invention) The polymer emulsion, which is the binder of the single-layer elastic emulsion paint of the present invention, has a layered structure and is composed of relatively large particles, so the layered structure has characteristics that are different from conventional multilayered emulsions. It is possible to more noticeably reflect this on the coating film performance. That is, the dry film obtained from the single-layer elastic emulsion coating material of the present invention can satisfy both low-temperature elongation and stain resistance.

(Examples) The present invention will be specifically described below based on Examples. Note that the scope of the present invention is not limited only to these examples. The viscosity of the emulsion was measured using a B-type viscometer (60 rpm, 25°C), the particle size was measured using the method described in Note 1), and the minimum film-forming temperature was measured using the minimum film-forming temperature manufactured by Nippon Rigaku Kogyo Co., Ltd. A film forming temperature measuring device was used.

Note that "parts" and "%" in the examples are based on weight.

Example 1 The polymerization reactor consisted of a reactor (2°C flask) equipped with a stirrer, a thermometer and a reflux condenser, a first monomer preemulsion source equipped with a stirrer, a second monomer preemulsion source equipped with a stirrer, and a second monomer preemulsion source equipped with a stirrer. It consists of two monomer pre-emulsion supply sources, a catalyst solution supply source, piping connecting these, and pumps (3 units). The reactor and the first supply source were connected by piping, and a pump was installed in the middle.

Separately, the reactor and the catalyst solution supply source were connected by piping, and a pump was installed in the middle. Further, the first monomer pre-emulsion supply source and the second monomer pre-emulsion supply source were connected by piping, and a pump was installed in the middle.

A reactor was charged with 240 parts of deionized water and heated to a temperature of 70°C. A first monomer pre-emulsion consisting of the following formulation was prepared in a first source.

Deionized water 167 parts Nucol 271A Note 2) 1.40 parts Nucol 1120 Note 3) 0.67 part Styrene
132 parts 2-ethylhexyl acrylate 360 parts Methyl methacrylate
181 parts acrylic acid 6.73
Part t-butyl hydroperoxide Note 4) 2.50
A second monomer pre-emulsion consisting of the following formulation was prepared in a second source.

Deionized water 109 parts Nucol 271A Note 2) 40.7 parts Nucol 1
120 Note 3) 19.5 parts styrene
132 parts 2-ethylhexyl acrylate 270 parts Methyl methacrylate 2
70 parts acrylic acid 6.73 parts t
-Butyl hydroperoxide Note 4) 2.50 parts The glass transition temperature of the polymerizable unsaturated monomer in the first monomer pre-emulsion is 0.4°C, and the second monomer pre-emulsion The glass transition temperature of the polymerizable unsaturated monomer in the emulsion is 20.4°C.

A catalyst solution consisting of the following formulation was prepared in a catalyst solution source.

Sodium formaldehyde sulfonate 8.0 parts Deionized water 40.0 parts The first monomer pre-emulsion was fed from the first source to the reactor at a constant rate over a period of 5 hours. At the same time, 55% of the second monomer pre-emulsion is transferred from the second source to the first source.
The feed was carried out at a constant rate over time, and the first source was kept stirring during the feed period to ensure that sufficient mixing occurred at all times. At the same time, catalyst solution was pumped into the reactor from a catalyst solution source at a constant rate over a period of 5 hours.

During the above operation, 70 parts of the reactor were kept at 2° C. and stirring was continued. After the introduction of the monomer pre-emulsion and the catalyst solution was completed, 70 parts of the reactor were kept at 2° C. for 1 hour and continued to be stirred. during that period. 5. 1-6 parts sodium formaldehyde sulfonate and deionized water. 7.50 parts of Rongalite aqueous solution consisting of -90 parts and 1.60 parts of t-butyl hydroperoxide were charged into the reactor in three portions over a period of 15 minutes.

After the above operation is completed, the reactor is cooled, and 12.7 parts of 25% ammonia is added to the reactor.
．． 80 parts and 2.00 parts of Suraoff 72N Note 6) were charged into the reactor, and then stirred for 10 minutes. After this time, the contents of the reactor were filtered through a 300 mesh silk cloth. The obtained latex had a solid content concentration of 68.9% and a viscosity of 1650 cps.
, pH 9.1, particle size 0.55 μm, minimum film forming temperature 7°
It was C. Furthermore, the elongation rate and stain resistance of the single-layer elastic paint using latex are shown in Table 1.

Comparative Example 1 The same polymerization reaction apparatus as in Example 1 was used. The following formulation was used as the first monomer pre-emulsion.

Deionized water 167 parts Nucol 271A Note 2) 1.40 parts Nucol ■1
20 Note 3) 0-67 parts styrene
132 parts 2-ethylhexyl acrylate 270 parts Methyl methacrylate 27
0 parts acrylic acid 6.73 parts t-
Butyl hydroperoxide Note 4) 2.50 parts The following formulation was used as the second monomer pre-emulsion.

Deionized water 109 parts Nucol 271A Note 2) 40.7 parts Nucol 1
120 Note 3) 19.5 parts styrene
132 parts 2-ethylhexyl acrylate 360 parts Methyl methacrylate 1
81 parts acrylic acid 6.73 parts t
-Butyl hydroperoxide Note 4) 2.50 parts The glass transition temperature of the polymerizable unsaturated monomer in the above first monomer pre-emulsion is 20.4°C, and the second monomer pre-emulsion The glass transition temperature of the polymerizable unsaturated monomer in the emulsion is 0.4°C.

Using the above monomer pre-emulsion, the same operation as in Example 1 was carried out to synthesize latte and tux. The obtained latex had a solid content concentration of 68.9% and a viscosity of 1426c.
ps, pH 9.2, particle size 0.65 μm, and minimum film forming temperature 14°C. Furthermore, the elongation rate and stain resistance of the single-layer elastic paint using latex are shown in Table 1.

Table 1 Note 1), Disk manufactured by Joyce-Loeb1
The particle size distribution is measured using a Centrifuge (MK-III type) particle size distribution analyzer, and the value of the particle size where the maximum peak appears in the obtained particle size distribution curve is defined as the "particle size" here. handle.

The measurement conditions were as follows: The spin liquid was 10 to 20 m of water.
Q. The rotation speed of the disc is 2000 to 6000 rpm.
, the temperature was 10 to 30°C, the sample dispersion medium was a methanol-deionized water (l:l by volume ratio) mixed solution, the sample dispersion concentration was 0.1 to 1.0% by weight, and the injection amount of the sample dispersion was is C
11 to 1.0rnj2.

Note 2) Anionic surfactant manufactured by Nippon Nyukazai Co., Ltd. Note 3) Nonionic surfactant manufactured by Nippon Nyukazai Co., Ltd. Note 4) 70% aqueous solution Note 5) Antifoaming manufactured by Jiryu Kakogyo Co., Ltd. Machinability 6) Antiseptic Penal Code manufactured by Takeda Pharmaceutical Co., Ltd. 7) Note 8) Note 9) Table 2 shows the paint composition. Mil base was dispersed for 30 minutes with Cowles di Solher. Film forming conditions are J I 5A-6910
Conforms to waterproof type.

The test method followed JI 5A6910 waterproof type.

Evaluation results from outdoor exposure tests. I did Bakuro for half a year in Hiratsuka City. The evaluation criteria are as follows.

○: There is little visible dirt, and it can be easily restored to its original state by washing with water.

◎: Dirt is clearly visible and does not return to its original state even after washing with water.

Table 2 Jiang 1 Note 1 Note 1 Note 1 Note l Note l Pigment dispersant manufactured by Seiatsu Co., Ltd. Titanium oxide manufactured by T-Riki Co., Ltd. Filler manufactured by Maruo Calcium Co., Ltd. Antifoaming agent manufactured by San Nobuco Co., Ltd. Rohm and Haas preservative Thickener manufactured by Asahi Denka Kogyo Co., Ltd.

Claims (1)

[Claims] The glass transition temperature of the central layer of particles in a polymer emulsion (
Ta) is -60 to -10°C, the glass transition temperature (Tb) of the surface layer is 0 to 100°C, and the glass transition temperature (Tc) of the intermediate layer is in the range of Ta≦Tc≦Tb, And Tb-Ta≧10°C, and the particle size is 0.3 to 3.
A single-layer elastic emulsion coating composition containing, as a binder, a polymer emulsion consisting of particles in the 0 μm range.