JPS61115971A - Water paint - Google Patents

Abstract

PURPOSE:To provide a water paint which has excellent viscosity stability and gives a coating film having excellent gloss, by blending an extender pigment obtd. by treating the surface of a fine particle of ground limestone with a surface treating agent contg. a fatty acid ester and an anionic surfactant. CONSTITUTION:A surface treating agent consisting of 10pts.wt. fatty acid ester (e.g. butyl stearate or methyl oleate) and 1-50pts.wt. sulfonic acid type or sulfate ester type anionic surfactant (e.g. dodecyl benzene-sulfonic acid or laurate) is prepd. 0.5-10pts.wt. said surface treating agent is added to 100pts.wt. fine ground limestone having an average particle size of 0.4-1mum obtd. by crushing limestone and classifying crushed powder. The treatment of the surface of the particle is carried out by a dry or wet process. The resulting surface- treated ground limestone is used as an extender pigment to provide the desired water paint.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to water-based paints, and more specifically, to water-based paints that have excellent dispersibility as extender pigments and that are surface-treated to give clear surface gloss. This invention relates to an aqueous material containing finely ground calcium carbonate.

``Prior art'' Problem 1: Problems that the invention should solve At present, extender pigments are hardly used.

On the other hand, heavy calcium carbonate with an average particle diameter of 1.5 μm or more is used in large quantities as an extender pigment in water-based paints that do not require high gloss in the coating film. However, since heavy calcium carbonate is inexpensive, it is merely used as an extender for reducing the cost of water-based paints and forming coatings.

In order to impart gloss to a coating film, the particles must not only be fine and dispersed as much as possible, but also have excellent compatibility with the vehicle. Therefore, the −order particle diameter is already 0.02~
Various surface treatment methods have been investigated to improve the dispersibility of fine precipitated calcium carbonate into water-based paints.
For example, a carboxylic acid type anionic surfactant and a sulfonic acid type or FtLf! A method of combined treatment with an ester type anionic surfactant (Japanese Patent Publication No. 46-157711, Phosphoric acid surfactant + 'l C treatment method ('l! + "Opening/closing 55
11i031) A method has been proposed in which a fatty acid is treated in combination with a sulfonic acid type or sulfuric acid ester type anionic surfactant (Japanese Patent Laid-Open No. 59-1571). However, little research has been done in terms of particle size, and few concrete results have been reported.

On the other hand, for water-based paints, a fine heavy calcium carbonate slurry obtained by pulverizing limestone by the eyebrow pulverization method is used as an extender pigment, as seen in, for example, Japanese Patent Application Laid-Open No. 58-204061. This is a highly concentrated slurry of 60 to 70 wt% or more, and a polymer dispersant of sodium polyacrylate is added to reduce the viscosity of the slurry. However, even with calcium carbonate obtained by these methods, it is still difficult to say that it is satisfactory as an extender pigment for water-based paints that require high gloss in current paint films. The reality is that there is a desire to develop extender pigments that can fully satisfy the required extender pigments for water-based paints.

In view of the above-mentioned circumstances, the present inventors have prepared a solution for solving the problem by using at least one of a fatty acid ester and a sulfonic acid type or sulfuric acid ester type anionic surfactant to prepare fine heavy calcium carbonate. The present invention was completed based on the discovery that by performing a combined treatment and using the same in water-based paints, a revolutionary and unexpected effect not found in conventional precipitated carbonaceous products or heavy carbonaceous slurry products can be obtained. be. That is, in the present invention, fine heavy calcium carbonate with an average particle size of 0.4 to 1.0 μm is mixed with (a) 10 parts by weight of fatty acid ester, and (b) sulfonic acid type and sulfate ester type anions. Fine ground calcium carbonate is treated as an extender pigment by adding 0.5 to 10 M parts of at least one kind of surfactant at a combined ratio of 1 to 50 parts by weight per 100 parts by weight of the above-mentioned ground calcium carbonate to treat the particle surface. The content is a water-based paint formulated as follows.

In the present invention, the average particle diameter refers to the length of one side of a cube, which is determined from the specific surface area measured with a constant pressure aeration type specific surface area measuring device, assuming that the heavy carnoum carbonate particles are cubic particles.

In order to obtain the fine, heavy calcium carbonate used in the present invention, limestone is pulverized dry or wet, with an average particle size of 0.
．． Adjust to fine particles of 4 to 1.0 μm. In the case of a dry method, the fine heavy calcium carbonate obtained in this manner may be pulverized with a micron mill, a vibrating ball mill, etc., and then classified with an air classifier, and in the case of a wet method, it may be pulverized with a ball mill, etc., and there is no particular restriction. The treatment is carried out in a dry manner using a combination of a fatty acid ester and at least one of a sulfonic acid type and a sulfuric acid ester type anionic surfactant.

The surface treatment agent used in the present invention includes fatty acid esters such as butyl stearate, methyl laurate, methyl oleate, etc., and sulfonic acid type or sulfate ester type anionic surfactants such as dodenruhenzene. Examples include sulfonic acid and lauryl sulfate. In addition, the total amount of (a) fatty acid ester and (i) sulfonic acid type or sulfuric acid ester type anionic surfactant necessary for the effects of the present invention to be manifested is as follows:
0°5-10 per 100 parts by weight of heavy calcium carbonate
Parts by weight. If it is less than 0.5 parts by weight, it will be difficult to make it into a paint, while if it is added in excess of 10 parts by weight, the gloss of the coating will not improve and it is not economical. The addition ratio of the ester type anionic surfactant is (b) 1 to 50 parts by weight of the sulfonic acid type or sulfuric acid ester type anionic surfactant to (a) 10 parts by weight of the fatty acid ester. (b) If the amount of the component is less than 1 part, high gloss of the coating film cannot be expected, and on the other hand, if it is added in excess of 50 parts by weight, the surface treatment effect will not improve, and dehydration will be difficult in wet processing, which is not preferable. .

Regarding the addition method of fatty acid ester and sulfonic acid type or sulfuric acid ester type anionic surfactant, if the product is wet-pulverized, the surface is naturally treated in a wet state, but even if it is dry-pulverized, it may be surface-treated in a wet manner. . The wet addition method is to add a sulfonic acid type or sulfuric acid ester type anionic surfactant while stirring a finely ground calcium carbonate water solution, and then add the fatty acid ester, or add it at the same time. However, it is more preferable to add the fatty acid ester as an emulsion using an aqueous solution of a sulfonic acid type or sulfuric acid ester type anionic surfactant.The thus treated slurry is dehydrated, dried, and pulverized to produce a product. shall be. On the other hand, when performing dry surface treatment, a Henschel mixer or the like is used.

The fine ground calcium carbonate obtained as described above is blended into a water-based paint in a conventional manner to produce a paint.

"Examples" The present invention will be described below with reference to specific examples and comparative examples, but the present invention is not limited by these in any way.

Reference Example 1 A slurry was prepared by dispersing heavy calcium carbonate having an average particle size of 1.5 μm in water using a stirrer so that the solid content was 40-t%. This slurry was ground using a sand grinder mill (DYNOMILL, manufactured by IIBA) at a rotation speed of 300 OR, P, M, and a flow rate of 61/hr.

The average particle size of crushed heavy carnoum carbonate is 0.55
It was μm. This heavy carbonated slurry with an average particle size of 0.55 μm has a solid content of 10 wt%! , and adjusted to a cloudy solution. Next, add 75 to 3 g of dodecylbenzenesulfonic acid.
Add 192 g of water at ℃, add 5 g of butyl stearate dropwise with strong stirring, and add 3 g of dodecylbenzenesulfonic acid.
200 g of an emulsion containing 5 g of butyl stearate was prepared. While stirring the previously prepared 10i+t% aqueous suspension of heavy calcium carbonate with an average particle size of 0.55 μm (LOOG), 200 g of the prepared emulsion of butyl stearate with dodecylbenzenesulfonic acid was added and stirred for 60 minutes. The mixture was stirred and surface-treated, then dehydrated, dried, and ground to form a sample.

Reference Example 2 A slurry was prepared by dispersing heavy calcium carbonate having an average particle diameter of 1.8 μm in water using a stirrer so that the solid content was 53 wt%. This slurry was processed using a sand grinder mill (manufactured by WBA, DYNOMILL) at 3 rotations.
00 OR, P, M,, flow rate 91! /br.

The average particle size of crushed heavy calcium carbonate is 0.8μ
It was m. This heavy calcium carbonate having an average particle diameter of 0.8 μm was adjusted to an aqueous suspension having a solid content of 10-t%. Next, dodecylbenzenesulfone @ 2g and 194g of water at 75℃
was added, and 5 g of butyl stearate was added dropwise with strong stirring to prepare 200 g of an emulsion containing 2 g of dodecylbenzenesulfone Mt and 4 g of butyl stearate. 1 of the previously prepared heavy calcium carbonate with an average particle size of 0.8 μm
While stirring 2000 g of the 011tVo water C suspension, 200 g of the prepared emulsion of butyl stearate with dodecylbenzenesulfonic acid was added, and the mixture was stirred for 60 minutes for surface treatment. This was dehydrated, dried, and ground to make a sample.

Reference example 3 Average particle size 10. After pulverizing limestone with a vibrating ball mill and classifying it with a wind classifier, the average particle diameter is 0.6μ.
m of ground calcium carbonate was prepared. This average particle diameter is 0
．． I (1w
Add 192 g of water at 75°C to 3 g of lauryl sulfate, which was dispersed in water using 5 at-degree stirring and adjusted to a 10 wt% aqueous suspension, and add stearic acid while stirring vigorously. 5 g of butyl was added dropwise to prepare 200 g of an emulsion containing 3 g of lauryl sulfate and 5 g of butyl stearate. The average particle diameter adjusted previously is 0.
10wt% water suspension of 6μm heavy calcium carbonate20
While stirring 00 g, 200 g of the prepared emulsion of butyl stearate lauryl sulfate was added,
The mixture was stirred for 60 minutes for surface treatment. This was dehydrated, dried, and ground to make a sample.

Reference Example 4 By changing the classification degree of Reference Example 3, the average particle diameter was 0.75 μm.
of heavy calcium carbonate was prepared. This average particle diameter is 0.
To 100 parts by weight of 75 μm heavy calcium carbonate, 2 parts by weight of methyl laurate and 1 part by weight of dodenruhenzenesulfonic acid were added together, and a sample was prepared by surface treatment using a Henschel mixer.

Example 5 A 10 nt% solid content aqueous suspension of precipitated calcium carbonate with a primary particle size of 0.07 μm was prepared by the sedimentation method, and 114 g of dodecylbenzenesulfone f was added to 19 g of 75°C water.
Add 0g of stearic acid, add 6g of stearic acid with strong stirring, add 4g of dodecylbenzenesulfonic acid and 6g of stearic acid.
200 g of emulsion containing g. 1 out of precipitated calcium carbonate with a primary particle size of 0.07 μm prepared previously.
While stirring 2000 g of the aqueous suspension, the prepared emulsion of stearic acid with dodecylbenzenesulfonic acid 20
0 g was added and stirred for 60 minutes to perform surface treatment. This was dehydrated, dried, and ground to make a sample.

Reference Example 6 An aqueous suspension of precipitated calcium carbonate having a primary particle size of 0.1 μm and a solid content of 19 wt % was prepared by a sedimentation method. Next, 190 g of water at 75° C. was added to 4 g of dodecylbenzenesulfonic acid, and 6 g of butyl stearate was added with strong stirring to prepare an emulsion @20 g containing 114 g of dodecylbenzenesulfone r and 6 g of butyl stearate. While stirring 2000 g of a 10 wt% aqueous suspension of precipitated calcium carbonate with large particles f1.1 μm prepared previously, 200 g of the prepared emulsion of butyl stearate with dodecylbenzenesulfonic acid was added, and the mixture was stirred for 60 minutes. Surface treated. This was dehydrated, dried, and ground to make a sample.

Reference Example 7 By changing the classification process of Reference Example 3, heavy calcium carbonate having an average particle diameter of 1.2 μm was prepared. A sample was obtained in the same manner as in Reference Example 3 in all other respects.

Reference Example 8 After hydrophilizing the slurry of ground calcium carbonate with an average particle diameter of 0.55 μm that was pulverized in Reference Example 1 to a solid content concentration of 7 wt%, the slurry was 1.0% by weight per 100 parts by weight of ground calcium carbonate.
Part by weight of sodium polyacrylate was added and slurried using a lab body spar. This heavy calcium carbonate slurry was used as a sample.

Reference Example 9 A slurry of heavy carnoum carbonate having an average particle diameter of 0.55 μm, which was ground at a reference percentage of 11, was dehydrated, dried, and ground as a sample without any surface treatment.

Examples 1 to 4, Comparative Examples 1 to 5 Using the samples prepared in Reference Examples 1 to 9 above, paints were formed using the following paint formulation and paint forming method. Table 1 shows the results of measuring the physical properties of the paint.

(a) Paint formulation ■ Missing combination mill base (parts by weight) Antifoaming agent (San Nobuco, 5N-8034L)
1.8 Wetting agent (San Nopco; Nopko Wet 5010 wt%) 2.4 Antifreezing agent (
15.6 Antifungal agent (ethylene glycol)
Katayama Chemical Industry Research Institute, 5LC-900) 0.6 Dispersant (Kao Soap; Demol EP 10 wL%)
20.8 Titanium white (Ishihara Sangyo i R-930)
206.8 sample (Reference example 1-g 3
104.4 Wednesday
832nd blend letdown (parts by weight) Millbase 181
．． 3 Emulsion (Showa Kobunshi; 290 Polysol AP-680) Film forming aid (CHV; C5-12)
25 Film forming aid (xylene) 1
3 Thickener (San Nopco ISN Thickener 612)
0.1 Thickener (Nnobu: 2; SN Thickener 613
) 0.15 ammonia water
0.15 adjusted water
A slight amount (b) Method for making a coating (2) Inadequate formulation: Dispersed for 20 minutes in a simple sG mill.

The rotational speed was 800R, P, M, and t) 6° 2-lack blending; stirred for 5 minutes with a lab body spar.

"Effects of the Invention" As is clear from the results in Table 1, the water-based paint containing the surface-treated finely ground heavy calcium carbonate of the present invention can be prepared using conventional precipitated calcium carbonate or wet-pulverized heavy calcium carbonate slurry. Significant effects on coating film gloss and viscosity stability are observed compared to water-based paints containing this product.

Claims (1)

[Claims] 1. Fine heavy calcium carbonate with an average particle size of 0.4 to 1.0 μm is added to (a) 10 parts by weight of fatty acid ester, and (b) sulfonic acid type and sulfate ester type anionic surfactants. The combination ratio of at least one of 1 to 50 parts by weight is 0.5 to 1 per 100 parts by weight of the above-mentioned heavy calcium carbonate.
A water-based paint containing 0 parts by weight of fine, heavy calcium carbonate, which has been added to treat the particle surface, as an extender pigment.