JPH02279771A - Water-base emulsion of sustained alkali release resin - Google Patents

Abstract

PURPOSE:To provide a water-base emulsion of a sustained alkali release resin providing a coating exhibiting excellent corrosion resistance for a long time by emulsion-polymerizing a polymerizable monomer in a specified amt. of water in the presence of an hardly water-soluble alkaline inorg. particle. CONSTITUTION:A water-base emulsion of a sustained alkali release resin is prepd. by emulsion-polymerizing 100 pts.wt. polymerizable monomer (A) (e.g. styrene or acrylonitrile) in the presence of 5 to 100 pts.wt. hardly water-soluble inorg. particle exhibiting alkalinity in water. As the practical examples of said inorg. particle, Portland cement, calcium hydroxide etc., are usually cited and a product with a particle diameter of about 0.5 to 15mum is pref. When an object is coated with the obtd. emulsion as an alkali ion is gradually leached when the coated film is brought into contact with water, it is possible to keep continuously the material to be coated alkaline and to provide excellent corrosion-proof characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to an aqueous alkali sustained-release resin emulsion used in water-based anticorrosive paints and the like.

[Conventional technology] Conventionally, t! Steel structures installed outdoors, such as buildings and machinery such as cranes, have their surfaces coated with anti-rust paint to prevent rust from being exposed to wind, rain and direct sunlight.

As such anticorrosive paints, solvent-type oil-modified alkyd paints are generally used. Recently, attempts have been made to use water-based paints in order to prevent environmental pollution, and such water-based paints include aqueous resin emulsions in which rust-preventive pigments such as barium metatarate are dispersed.

[Problem to be Solved by the Invention 1] However, in water-based anti-corrosion paints made of water-based resin emulsions in which anti-rust pigments such as barium meta-borate are dispersed, barium meta-borate is expensive, and furthermore, it is difficult to disperse in water. Therefore, it was not possible to increase the amount of barium metaborate added, and there was a limit to improving the rust prevention properties.

On the other hand, polymer cement mortar in which portland cement is post-mixed with a resin aqueous emulsion is also known (Japanese Patent Publications No. 62-25639 and 62-25640). As it is difficult to make it into one liquid, cement and I#In! It was necessary to mix the emulsion.

[Means for Solving the Problems] In view of the above problems, the present inventors have produced an inexpensive, high-performance water-based anticorrosive paint that does not use expensive barium metaborate and does not require on-site compounding. With the purpose of
As a result of extensive research, we have found that by using specific inorganic particles and blending these inorganic particles into capsules, we have been able to improve dispersibility and limit the amount added.
Furthermore, the present inventors have discovered that an emulsion with excellent storage stability in liquid form can be obtained, leading to the completion of the present invention.

That is, the present invention fAJ polymerizable 100 parts by weight.

FB+ poorly water-soluble inorganic particles showing alkalinity in water 5~
In the presence of 100 parts by weight.

This is an aqueous alkali sustained-release resin emulsion obtained by emulsion polymerization.

[Detailed Description of the Invention] 111 Polymerizable Monomer fAl Examples of the polymerizable monomer of component fA) include vinyl monomers. These vinyl monomers include loobropil methacrylate fTg 81'Cl, styrene (1
g100℃), acrylonitrile (Tg 100℃),
Methyl methacrylate (Tg 105°C), methacrylic acid (Tg 130°C), itaconic acid (Tg 130°C1)
, acrylamide (Tg 15:1℃), acrylic acid 2
-Ethylhexyl (Tg-85°C1, lobutyl acrylate fTg-54°C), ethyl acrylate fTg-2
2°C), isopropyl acrylate lTg -5°C), 2-ethylhexyl methacrylate (Tg -5°C1, n-propyl acrylate (Tg 8°C), loubyl methacrylate fTg 20°C), vinyl acetate (Tg 30°C)
, monobutyl acrylate (Tg 45°C1, 2-hydroxyethyl methacrylate (Tg 55°C), ethyl methacrylate iTg 65°C), isobutyl methacrylate tTg 67°C), vinyl chloride fTg 79°C), vinylidene chloride ( Tg-18°C), ethylene, etc. Further, these vinyl monomers can be used alone or in combination of two or more.

The type and amount of these polymerizable monomers to be used are determined by taking into consideration the usage temperature of the resulting emulsion and using the glass transition point of the resulting resin as a guide. For example, when the emulsion is used at room temperature (20°C), the glass transition point of the resin in the emulsion is selected from 165°C to +20°C. In addition, when forced drying (60 to 200°C) is carried out, the aqueous emulsion resin to be obtained has a glass transition point of +20 to 80°C.

Furthermore, as a component of the vinyl monomer of the polymerizable monomer, an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, itaconic acid, or maleic anhydride is added in an amount of 0.1 to 3 of the amount of the vinyl monomer component used. Used in weight percent:
It is useful for increasing the adhesion of the film to the adherend (metal)6 Therefore, preferable vinyl monomers to be subjected to emulsion polymerization are styrene, acrylonitrile, lower alkyl methacrylate tc+-ca) esters, etc. Selected monomers 20-80% by weight (bl lower alkyl acrylate [C, ~ C, l esters 30-70% by weight (cl unsaturated carboxylic acids 0.1-3% by weight (d
1 Acrylamide, phenylmaleimide, methylol acrylamide 0 to 1 weight% tel Other monomers 0 to 20 1% by weight mixture.

(2) Poorly water-soluble inorganic particles FB) When the polymerizable monomer is emulsion polymerized, the poorly water-soluble inorganic particles exhibiting alkalinity in water, which are present in q during emulsion polymerization, are preferably 5 g or less in 100 g of water at 20°C. In this method, poorly water-soluble inorganic particles are used that dissolve only in an amount of 3 g or less.

Examples of such inorganic particles include general particles, CaO, and C.
There are a(OH)a, ordinary Portland cement, magnesia cement, early strength Portland cement, etc.
Among these inorganic particles, Portland cement is generally preferred because it is inexpensive.

However, since cements such as Portland cement, magnesia cement, and early-strength Portland cement coagulate due to hydration reactions with water, it is preferable to start emulsion polymerization of vinyl monomers as soon as possible after mixing with water.
Further, a hydration reaction retarder such as sodium gluconate may be added for the purpose of controlling the hydration reaction of cement.

These poorly water-soluble inorganic particles generally have a particle size of 0.1 to
1 tlOHm, preferably 0.5-15 um is used.

(3) Protective colloid fc) In addition to the above essential components (A) and (8), it is preferable to use a protective colloid as the fc) component.

The protective colloid maintains the uniform dispersion of poorly water-soluble inorganic particles in the resin aqueous emulsion to eliminate unevenness in rust prevention performance when the resin aqueous emulsion of the present invention is used as a paint, and also emulsion polymerizes to improve the vinyl monomer content. It has the effect of assisting in the encapsulation of poorly water-soluble inorganic particles by the polymerized substance, and is preferably allowed to coexist with the poorly water-soluble inorganic particles of the iB+ component when carrying out the emulsion polymerization of the component fA).

Examples of such protective colloids include hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, and polyvinylpyrrolidone. The protective colloid agent is used in an amount of 2 parts by weight per 100 parts by weight of the vinyl monomer.
It is used in a proportion of ~20 parts by weight.

(4) Emulsion polymerization The method for emulsion polymerization of the polymerizable monomer is performed except that the poorly water-soluble inorganic particles are present.

It can be carried out in a manner similar to known emulsion polymerization methods.

(5) ffi ratio The amount of poorly water-soluble inorganic particles used as component IB) is
5 to 1 per 100 parts by weight of polymerizable monomer of Al component
It is important to use a proportion of OO parts by weight. If the amount of these poorly water-soluble inorganic particles used is too much than the above range, polymerization stability will be impaired, and if it is too little, the amount of alkaline degradation will be too small, and long-term sustainable effects such as rust prevention will not be exhibited. Not done.

(6) Other additives The aqueous alkali sustained-release resin emulsion of the present invention thus produced is produced in the absence of poorly water-soluble inorganic particles to the extent that its properties such as rust prevention are not impaired. The aqueous resin emulsion prepared can be further mixed.

Also similar to traditional resin water emulsions.

Various additives can be blended. These additives may be added before or after the start of emulsion polymerization depending on the purpose. , 2. Examples of additives include 1. For example, plasticizers, antifoaming agents, antisettling agents, fluidity regulators, antifreeze agents, lower alcohols, pigments, dyes, sand, fillers, wetting agents, water repellents, There are texture regulators, pH regulators, etc.

(7) Alkaline sustained-release resin aqueous emulsion The alkali sustained-release resin aqueous emulsion of the present invention produced in this way is produced by the presence of poorly water-soluble inorganic particles (B) that exhibit alkalinity in water (Al Since the polymerizable monomers as components are emulsified and combined, the resulting product is a polymer composition having a structure in which the slightly water-soluble inorganic particles of component (B) are covered with a polymer of the polymerizable monomer of component fA). or a single emulsion polymer of the polymerizable monomer of component (A) and a polymer of the polymerizable monomer of component (A) around the poorly water-soluble inorganic particles of component (B). The mixture of the polymer composition and the coated structure was uniformly dispersed in water.

around such poorly water-soluble inorganic particles of +8+ component.
The aqueous emulsion made of a resin wave-layered with a polymerizable heptad emulsion polymer containing an Al component contains an emulsion with an inorganic material as a core that exhibits alkalinity in water as a base dispersion for an aqueous anticorrosive paint. When used as a water-based anticorrosion paint, the slightly water-soluble inorganic particles exhibiting alkalinity gradually dissolve from this base dispersion, so that the adherend can be kept alkaline at all times. Therefore, the aqueous rust-preventive paint using the aqueous alkali sustained-release resin emulsion of the present invention does not contain a rust-preventive pigment such as barium 1llllate (but can still exhibit excellent rust-prevention properties over a long period of time).

Moreover, since the poorly water-soluble inorganic particles of the fil component are bound by the emulsion polymer of the monomer monomer of the +Al component, they have good dispersibility and can be blended in a large amount into the resin aqueous emulsion.

Furthermore, even when a hydration-reactive inorganic substance such as Portland cement is used as component iB), since it is encapsulated by a resin film, its water-hardening reaction is suppressed and it has long-term storage stability. Furthermore, since the hydration reactivity of the cement, that is, the alkali release property, can be controlled by controlling the thickness of the coating, the alkali can be released over a longer period of time.

(8) Applications The aqueous alkali sustained-release resin emulsion of the present invention can be used as a base for anticorrosive paints.

[Example] The aqueous alkaline sustained-release resin emulsion of the present invention will be further described below with reference to Examples, but the present invention is not limited thereto.

The percentages and parts used in the following Examples and Comparative Examples are by weight unless otherwise indicated.

In addition, in the following Examples and Comparative Examples, the performance of the produced aqueous resin emulsions and aqueous antirust paints was measured by the following method.

■, Resin aqueous emulsion il + polymerization stability ○ Good condition Slight occurrence of aggregates △ Many aggregates × Coagulation (2) The alkali-releasing resin aqueous emulsion was vacuum-dried, and the proportion of poorly water-soluble inorganic particles contained was 1 Offi. % of the dry emulsion polymer is dispersed in water. Separately, 810 parts by weight of cement was dispersed in the same amount of water, both were left at room temperature for 7 days, and the aqueous solution was separated by filtration.

Take 100 ml of each aqueous solution and perform neutralization titration with a 0.1N-1t (J aqueous solution. When the neutralization titer of the cement-only dispersion aqueous solution is taken as 100, the neutralization titer of the emulsion polymer is the alkali release. This was used as the evaluation value for sex.

+! , the change in viscosity of the water-based rust-preventing paint (3) storage-stable formulation after being left at 20°C for one week.

○ No viscosity change Mouth: Slightly thickened Δ Thicken X coagulation (4) Dispersion stability Evaluate the presence or absence of filler sedimentation in the formulation.

O No filler settling Slight settling △ Filler settling × Filler settling, coagulation (5) Rust prevention and polished mild steel plate with degreased blister surface (70mm x 150mm x 0.5mm)
A test piece was prepared by applying it twice with a brush (0.7g XZ times) on a 8m5 area and then drying it at room temperature for 7 days.The following experiments were conducted to evaluate the presence or absence of rust and the amount of blisters.

(5a) Salt Water Spray Resistance The corrosion resistance of the coating film after being exposed to a salt water spray tester for 48 hours was evaluated based on the amount of blisters generated and the area ratio of rust.

(5b) Hot water resistance Evaluated after being immersed in warm water at 60°C for one week.

(5c) Water resistance Evaluated after being immersed in water at 20°C for one week.

Example 1 '5! of alkaline emulsion! A reaction vessel equipped with a temperature controller, an anchor type stirrer, a reflux condenser, a supply container, a thermometer, and a nitrogen inlet tube was charged with 5 liters of ion-exchanged water.
After charging 0 parts and 1 part of sodium dodecylbenzenesulfonate and purging the inside of the reactor with nitrogen gas, 10% of the total amount of raw material A shown below was added into the reaction container, and the mixture was heated to 80°C. The mixture was emulsified by heating and stirring.

Hadan A Methyl methacrylate 40 parts n-butyl acrylate 40 parts Stynone
18 parts acrylic acid
1 part acrylamide
1 part ordinary Portland cement 10 parts hydroxyethyl cellulose 10 parts sodium dodecylbenzenesulfonate 1 part ion-exchanged water 50 parts Next, 10% of an aqueous solution prepared by dissolving 2 parts of potassium persulfate in 30 parts of ion-exchanged water was added under stirring.

Furthermore, the remaining raw material A and the potassium persulfate aqueous solution were gradually fed into the reaction vessel over a period of 4 hours. After supply ends, 3
After stirring while maintaining the same temperature for a period of time, raw material A was subjected to emulsion polymerization to obtain resin aqueous emulsion A having a solid content of 35%.

Table 1 shows the evaluation results of the polymerization stability and alkali release property of the aqueous alkali sustained-release resin emulsion A produced in this manner.

351 parts of the thus produced aqueous alkaline sustained-release resin emulsion A were mixed with 372 parts of Mill Base formulated with the following composition, and further mixed with 25 parts of Dexanol and Latecol D (West German BASF). thickener, trade name) 1.5
A water-based anti-corrosion paint was manufactured by blending the following parts.

Mill base water 1
50 parts 28% ammonia water 2 parts l
θ% Sodium polyphosphate 20 parts Talc
Table 2 shows the performance evaluation results of 200 parts of the water-based anticorrosion paint thus produced.

Examples 2 to 9 and Comparative Examples 1 to 7 Resin aqueous emulsions were produced in the same manner as in Example 1, except that the amounts shown in Table 1 were used, and further, the amounts shown in Table 2 were used. A water-based anticorrosive paint was produced by the same method as in Example 1.

We conducted the evaluation.

However, in each comparative example, Portland cement or calcium hydroxide was not blended during the emulsion polymerization of vinyl monomers, so the resulting emulsions (F, H and J
) was later mixed with cement or barium metaborate.

[Effect of the invention 1] Since the aqueous alkaline sustained-release resin emulsion of the present invention contains a resin particle emulsion with an inorganic material as a core that exhibits alkalinity in water as a base dispersion, when used as a water-based anticorrosion paint, 2. When water comes into contact with the formed film of this base dispersion, alkali ions are gradually eluted from the poorly water-soluble inorganic particles, so that the fracture material can be kept alkaline at all times. Therefore, even if there is no rust-preventing pigment, the layer can exhibit long-lasting rust-preventive properties.

Moreover, since the poorly water-soluble inorganic particles (8 parts component) are encapsulated by the emulsion polymer of the polymerizable monomer (fAl component), they have good dispersibility and can be blended in large quantities. can.

Claims (1)

[Claims] (1) (A) 100 parts by weight of the polymerizable monomer (A) is mixed with 5 to 1 part of poorly water-soluble inorganic particles (B) that exhibit alkalinity in water.
An aqueous alkali sustained-release resin emulsion obtained by emulsion polymerization in the presence of 0.00 parts by weight.