JPS61221253A - Aqueous coating composition - Google Patents

Abstract

PURPOSE:To provide the titled compsn. having excellent resistance to corrosion and water, adhesion and quick dryness, consisting of a crystalline copolymer and a non-crystalline copolymer. CONSTITUTION:55-95% (by weight; the same applies hereinbelow) vinylidene chloride, 45-5% at least one ethylenically unsaturated monomer [e.g. methyl (meth)acrylate] and optionally 0.01-5% at least one unsaturated carboxylic acid [e.g. (meth)acrylic acid] are copolymerized to obtain a crystalline copoly mer (A) having a glass transition temp. of -10-60 deg.C. 40-97% polymer A is blended with 60-3% noncrystalline copolymer having a glass transition temp. of -20-60 deg.C obtd. by polymerizing a monomer mixture of 0-50% vinyli dene chloride and 100-50% at least one ethyle-nically unsaturated monomer (e.g. those described above).

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention [Field of Industrial Application] The present invention relates to a quick-drying aqueous coating composition that has excellent corrosion resistance, adhesion, and water resistance.

[Prior art and its problems]

Conventionally, solvent-based compositions have been used as coating compositions due to their performance and cost. However, in recent years, aqueous coating compositions have been increasingly used, which have problems in terms of their toxicity, flammability and environmental pollution.

Alkyd resins and acrylate resins are currently used in typical aqueous coating compositions.

However, since this aqueous alkyd resin contains many ester bonds in its main chain, it is easily hydrolyzed, and aqueous coating compositions containing this alkyd resin have poor storage stability, and the coating film that can be obtained does not deteriorate. has the disadvantage of poor performance such as water resistance, alkali resistance, and weather resistance. Furthermore, aqueous coating compositions containing acrylic acid ester resins have a drawback of poor corrosion resistance.

Japanese Patent Publication No. 59-41467 and Japanese Patent Publication No. 59-4166 relate to a coating resin composition formed by total emulsion polymerization of a monomer mixture mainly composed of vinylidene chloride.
There is a publication No. 0.

In addition, a method for producing latex characterized by mixing a 2N1 type latex obtained by polymerizing a monomer mixture containing vinylidene chloride at a high concentration was published in 1983.
No. 8702, but this latex has particularly poor drying properties.

Furthermore, production of a latex characterized by adding a monomer mixture mainly consisting of vinylidene chloride to a cool latte obtained by emulsion polymerization of a monomer mixture mainly consisting of vinylidene chloride and carrying out emulsion polymerization. Japanese Patent Publication No. 59-937 as a method
No. 06, however, the latex has particularly poor corrosion resistance. None of these techniques have the same excellent performance as Palanne in all aspects of corrosion resistance, adhesion, water nutrient and quick drying properties.

(2) Structure of the Invention [Means for Solving Problems] In view of the drawbacks of the conventional aqueous coating compositions described above, the present invention addresses various requirements such as corrosion resistance, adhesion, water resistance, and quick drying properties. In order to develop an aqueous coating composition that satisfies the following, the present invention was completed as a result of intensive research.

That is, the present invention is made by polymerizing a monomer mixture consisting of 55 to 95% by weight of vinylidene chloride and 45 to 5% by weight of one or more types of ethylenically unsaturated monomer copolymerizable with vinylidene chloride,
-10°C to 60°C glass transition temperature (hereinafter referred to as Tg)
Copolymer A having
The present invention is an aqueous coating composition characterized in that copolymer B having a Tg of 60 DEG C. is copolymerized with 40 to 97 weight i% of potash, and copolymer B is 60 to 6 weight percent.

[Copolymerization great person]

The copolymer is a crystalline copolymer consisting of 55 to 95 parts by weight of vinylidene chloride and 5 to 45 parts by weight of one or more ethylenically unsaturated monomers copolymerizable therewith. It is a copolymer obtained by copolymerizing a mixture of polyesters, and has a Tg of -10°C to 60°C. If the amount of vinylidene chloride is less than 55% by weight, the film will not reach a predetermined degree of crystallinity, the gas barrier properties will be poor, and sufficient corrosion resistance and water resistance will not be obtained. Furthermore, in order to have sufficient crystallinity, it is preferable that the weight of vinylidene chloride is 70% or more.

The higher the vinylidene chloride content, the better the gas barrier properties, but vinylidene chloride is 95 times heavier! If it exceeds the limit, the adhesion and weather resistance will be poor, and the storage stability of the emulsion itself will be poor, making it unsuitable for practical use.

The Tg of the secondary polymer A is preferably in the range of 5°C to 50°C. If the Tg is less than -10°C, the hardness of the obtained copolymer will be too hard and the blocking property will be poor.
If the temperature exceeds 60°C, the hardness of the resulting polymer will be too high and the adhesion will be poor.

Any number of ethylenically unsaturated monomers copolymerizable with vinylidene chloride may be used, but in particular methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, and 2-ethylhexyl acrylate. , methyl methacrylate, vinyl acetate, styrene,
It is preferable to use vinyl chloride, acrylonitrile, and at least one unsaturated carboxylic acid selected from acrylic acid, methacrylic acid, itaconic acid, etc., and the amount used is preferably 0.01 to 5 times. is preferred.

The adhesion of the aqueous coating can optionally be further improved by lowering the molecular weight of copolymer A below that which would be obtained if it were polymerized normally. Kon
can be easily done by using a chain transfer agent during the copolymerization reaction. Suitable chain transfer agents include long-chain alkyl mercaptans, such as n-octyl (Cl2CHtb), etc.The amount of chain transfer agent used is generally 0.2 to 5 times the amount of total monomers used. t%, preferably 0.5 to 2% by weight.

[Polymer B]

Copolymer B is an amorphous polymer other than copolymer A and has a temperature range of -20°C to 60°C, more preferably 5°C to 5°C.
It is a polymer with a Tg in the range of 0°C.

The reason why the Tg must be in the range of 120 DEG C. to 60 DEG C. is due to the same reason as in the case of copolymer A. The ethylenic uncelled monomer used in the production of polymer B may have any number of layers, but in particular methyl acrylate, ethyl acrylate,
At least one monomer selected from the group consisting of propyl acrylate, butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, vinyl acetate, styrene, vinyl chloride, vinylidene chloride, and acrylonitrile 90 to 9999 It is preferable that the weight ratio is 0.01 to 10% by weight of at least one non-anastomeric carboxylic acid selected from acrylic acid, methacrylic acid, itaconic acid and the like.

As copolymer B, vinylidene chloride 0 to 50 Iiu
4. It is preferable to polymerize a monomer mixture consisting of 100 to 501t4 of one or more monomers copolymerizable with vinylidene chloride, and 5 to 50% by weight of vinylidene chloride,
One or more monomers copolymerizable with vinylidene chloride 95~
More preferred is one obtained by polymerizing a monomer mixture consisting of 50% by weight.

The adhesion of aqueous coating compositions can be further improved by lowering the molecular weight, optionally using methods similar to copolymerization.

The aqueous coating composition of the present invention is composed of a front side copolymer A and a copolymer B, and the copolymer A has a weight of 40 to 97 weights, and the weight of polymer B has a weight of 60 to 3 weight.

The blending ratio is preferably 55 to 90 weight of the copolymer fraction and 45 to 10 weight of polymer B.

When the proportion of copolymer A is less than 40% by weight, that is, polymer B
If the proportion of copolymer exceeds 60% by weight, the corrosion resistance and water resistance will be insufficient.
If it exceeds 4, that is, if the proportion of polymer B is less than 3% by weight, the adhesion, weather resistance, and drying properties will be insufficient.

Copolymer A and polymer B are usually easily obtained by a conventional emulsion polymerization method, and the n1 aqueous coating composition consists of these two.
Obtained by mixing different types of polymers in a conventional manner.
Ru.

One or more of agents, preservatives, antifoaming agents, pigments, rust inhibitors, freeze stability improvers, colorants, etc. can be used.

The aqueous coating composition of the present invention can be diluted with an aqueous medium to any desired ratio.

In that case, if the solid content concentration is less than 20% by weight, the drying property will be poor, so it is practically preferable h0 Next, the method of using the aqueous coating composition of the present invention will be explained. '/fI? (in terms of solid content) and 10~jDOf! /dc solid content) is preferred. In other words, if the film is too thin, it may not exhibit sufficient barrier properties, or the film may remain stable and adhered to the object under slight contact or climatic conditions such as temperature and humidity. 1. Corrosion resistance is impaired. on the other hand,
If it is too thick, drying properties will be poor, resulting in poor workability and economical efficiency.

In addition, materials to which the aqueous coating composition of the present invention can be applied include metallic materials such as iron plates, wood materials such as ordinary veneer and plywood, inorganic materials such as plasterboard and slate boards, and expanded polystyrene. Synthetic resin materials, etc. are available.

A good film can be formed by applying a predetermined amount of the aqueous coating composition of the present invention to these objects by brushing, spraying, dipping, or using various coaters, and then drying with air drying, hot air drying, etc. can be formed.

In particular, by using a steel material as the object, features such as corrosion resistance and water resistance can be fully exhibited.

[For production]

The feature of the present invention is that the crystallized film of vinylidene chloride-based copolymer has excellent gas barrier properties and water resistance, and by utilizing the fact that it has excellent gas barrier properties and water resistance, it overcomes the disadvantages of vinylidene chloride such as weather resistance, adhesion, and drying properties. The disadvantage is that it has been improved by blending an amorphous copolymer.

Vinylidene chloride copolymer θ forms a film with high gas barrier properties only on the surface and requires a long time to dry.On the other hand, if the vinylidene chloride content is lowered to improve drying properties,
This has the disadvantage that the original gas barrier properties are reduced. Therefore, in the present invention, by blending an amorphous copolymer with a crystalline vinylidene chloride copolymer, the performance is improved to be the same as or more than that of the amorphous copolymer. The gas barrier properties of copolymers with the same composition as the blend do not deteriorate, and by controlling the blend ratio, it has almost the same gas barrier properties as vinylidene chloride copolymers, and has significantly greater drying properties. is improved.

[Examples and comparative examples]

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

It should be noted that parts, percentages and ratios on each side are by weight.

Moreover, the performance of the aqueous coating composition was measured by the following method.

E based on 100 parts of resin solid content of the obtained n7'5 coheavy metal body.
macol Colors Black C (trade name, manufactured by Sanyo Shiki ■, titanium white 20 parts soybean-butyl cello 3 parts isopropyl alcohol 2 parts were blended and dispersed with a paint conditioner to obtain an aqueous coating composition.

The viscosity of this aqueous coating composition was adjusted with water, and it was applied to a polished mild steel plate polished with a #520 sand vapor using a bar coater to a film thickness of 40 μm. Dry the paint film at 20℃ and humidity 75
% atmosphere for 7 days.

The performance of the aqueous coating composition was evaluated by the following test items.

Test item (1) Adhesive goblin test Make 100 goblins of 1w width, stick cellophane adhesive tape on top of them, peel off the tape vigorously, test, and evaluate based on the number of pieces remaining.

(2) Water resistance: Visually inspect the condition of the painted surface by immersing it in tap water at 20°C.
o (3) Corrosion resistance: Cross-cut the paint film that has dried for 7 days with a cutter knife to reach the substrate, and test it with a salt spray tester (5 times salt water).
After testing for 20 hours, the condition of the painted surface (width of rust from the cross-cut portion) was examined.

(4) Drying property The finger touch time (the time until no tack remains after touching the coated surface with a finger) was examined in an atmosphere of 20°C and humidity of 75°C.

The abbreviations of the monomers used on each side are as follows.

VDC: Vinylidene chloride MA: Methyl acrylate EA: Ethyl acrylate BA: n6-butyl acrylate HA: 2-ethylhexyl acrylate VC=
Vinyl chloride MMA: Methyl methacrylate St: Styrene MAA: Methacrylic acid AA: Acrylic acid Mayu The Tg of Copolymer A and Polymer B was measured by differential scanning calorimetry.

Reference Example 1 (Production of Copolymer A) Copolymer A was produced in the following manner using the five types of monomer compositions shown in Table 1.0 Temperature controller, stirrer, supply container, temperature Water is placed in a reaction vessel equipped with a gas meter and a nitrogen gas inlet tube.
56.2 parts Sodium dodecylbenzenesulfonate 0.2fHS Potassium persulfate
0.3 part was charged, the inside was replaced with nitrogen gas, the pressure was then reduced, nitrogen gas was further introduced, and the pressure was again reduced.

Next, while maintaining the temperature inside this reaction vessel at 50°C and stirring, 90 parts BA and 9 parts AA of VDC were added from a separate vessel in which the inside of this reaction vessel was replaced with nitrogen gas.
1 part water
A mixture consisting of 45.5 parts and 1.8 parts of sodium dodecylbenzenesulfonate was continuously fed using a metering pump over a period of 10 hours.

After the completion of feeding a predetermined amount of the mixture, polymerization was continued at 50° C. until the internal pressure of the reaction vessel reached Okgu/dG to produce copolymer A having a solid content of about 50%.

The resulting five types of copolymers At-son are referred to as ACI-C5.

In the production of C2 using vinyl chloride, vinyl chloride was divided into portions every 10 minutes and press-fitted over a period of 10 hours.

Reference Example 2 (Manufacture of Polymer B) Polymer B was manufactured in the following manner using the three types of monomer compositions shown in Table 2.

Water 571 in the same reaction vessel as copolymer A
! Is Sodium Dodecylbenzenesulfonate 1
3rd part St S part HA
4.5 part AA
Charge α5 part and replace the inside with nitrogen gas.

Next, the temperature inside this reaction vessel is raised to 70°C while stirring, and 3 parts of aqueous potassium persulfate solution is added. 1
After 5 minutes, 45 parts of St.
40.5 part AA
4.5 parts water
A mixture consisting of 1.7 m of 3 parts of dodecylbenzenesulfonic acid was continuously pumped in over 4 hours using a metering pump.

At the same time, 12 parts of aqueous chlorium persulfate solution was added to a metering pump to obtain three types of polymers, each of which was referred to as C6 to C8.

Note that C8, which was copolymerized with vinylidene chloride, was produced in the same manner as Polymer A.

Comparative Examples 1 to 5 Aqueous coating compositions consisting only of copolymers 01 to C5 were prepared, and their performance was evaluated.

The results are shown in Table 1.

Comparative Examples 6-8 Aqueous coating compositions consisting only of polymers C6-C8 were prepared and their performance was evaluated.

The results are shown in Table 2.

Examples 1 to 6 and Comparative Examples 9 to 12 Aqueous coating compositions were prepared by mixing copolymers C1 to C5 and polymers C6 to C8 in the proportions shown in Table 3, and the performance was evaluated for the compositions. did.

The results are shown in Table 3.

(3) Effects of the Invention The aqueous coating composition of the present invention is not only unparalleled to conventional aqueous coating compositions in terms of corrosion resistance, adhesion, water resistance, and quick drying properties, but is also superior to conventional aqueous coating compositions in terms of corrosion resistance and drying properties. has very high industrial value because it has performance close to that of solvent-based coatings.

Claims (1)

[Claims] 1. Polymerized monomer mixture consisting of 55 to 95% by weight of vinylidene chloride and 45 to 5% by weight of one or more types of ethylenically unsaturated monomer copolymerizable with vinylidene chloride -10°C to 6
Consisting of a copolymer A having a glass transition temperature of 0°C and a copolymer B having a glass transition temperature of -20°C to 60°C other than the copolymer A, the copolymer A weighs 40 to 97%. %
, an aqueous coating composition characterized in that copolymer B is 60 to 3% by weight.