JPS58204061A - Water paint - Google Patents

Abstract

PURPOSE:To provide water paint in which various properties such as viscosity, gloss, hiding power, workability, brushability and weather resistance are improved on the whole, by blending water-ground calcium bicarbonate having a particle size within the specified range as a pigment for a water paint compsn. CONSTITUTION:Calcium bicarbonate is water-ground so that the value of S of formula II will satisfy the condition of 5.0<=S<=9.0 when average particle size D is calculated from formula I , wherein when all particles are classified into 11 groups, the median of the particle size of each group is d1X10<-6>m, the median d1 of the first group is d1=(0+0.4)/2.10<-6>m, the median of the second group is d2=(0.4+0.5)/2.10<-6>m in turn, d3=0.5, d4=0.65... d10=4.5, and further all particle having a particle size of 5.0 or above are classified as the 11th group whose median is evenly d11=5.5, and w1 is wt% of each group. The value So of formula III represents the S value where calcium bicarbonate is not water- ground. Water paint is prepd. by using such calcium bicarbonate as a pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the comprehensive improvement of various properties of a water-based paint containing calcium carbonate as a pigment, such as viscosity, gloss, concealing property, 1 workability, brush handling property, and 9M weatherability.

Calcium carbonate, which is a pigment contained in water-based paints, can greatly affect the viscosity, gloss, hiding properties, brushability, workability, weather resistance, etc. of the paint, depending not only on its particle size but also on the manufacturing method. well known. Conventionally, this type of calcium carbonate has been broadly classified into λ types based on the manufacturing method. They are precipitated calcium carbonate, which is chemically synthesized, and 7'C heavy calcium carbonate, which is mechanically crushed from limestone. The former has a uniform particle size but is very fine, so even if the amount of violet added is kept relatively small, the viscosity of the paint will thicken significantly and may even cause problems such as becoming pudding-like. However, if a treatment agent is used to prevent secondary agglomeration, the disadvantage is that there is a lot of foaming during application.

On the other hand, mechanically pulverized heavy calcium carbonate has a wide particle size distribution range and lacks homogeneity, and its ability to classify by elutriation and water coverage is limited, so contamination with large particles is unavoidable. For this reason, the gloss, hiding property, and weather resistance of the coating film are significantly reduced, and the current situation is that it is only used as a thickening agent.

Recently, however, it has become known that wet pulverization can produce calcium oxides with a narrow particle size distribution. This means, for example, that it can be tested what the viscosity distribution of a trap with good viscosity should be.

It will also be possible to demonstrate that the properties of calcium carbonate particles may differ if there are differences in the manufacturing method, whether it is wet pulverization, dry pulverization, or chemical synthesis. Therefore, it becomes necessary to discuss analysis based on particle size distribution.

Analysis of the particle size distribution of the pellet is generally performed using the following specific surface area lff1. That is, it is expressed as an S value. Now, we will classify by l/class shown in the following table.

In this equation, di is the median particle size of each class. Using this classification, the uniform particle tL D lr is defined by the following equation + 11 equation.

However, the unit of di is /θ-61B% represents the value measured by the weight of all particles in the i-th class after classifying the sample. Rivi is a company of /Qθchi. Furthermore, using this average particle sound, the specific surface area, hitting, and S value can be calculated using the following formula (2).
Define it using the formula.

The total weight of all particles belonging to each class is measured as follows. Using a particle size distribution analyzer 6111 (the data in this specification was obtained using a Shojin centrifugal sedimentation type particle size distribution analyzer CP-30 model), a. ! Add 10 to 100% of the sample and shake for 10 minutes.

Calcium carbonate having an S value defined in this way, for example, calcium carbonate having a low S value, has coarse particles. S
If the value of V is too large, the particles will be too small and will be unsuitable as a paint due to viscosity and other properties. Well then,
The question is whether there is a suitable S value, but calcium carbonate obtained by dry grinding has a wide range of particle dust distribution even if the S value is neither too high nor too low. Both of them contain coarse particles, and it is almost impossible to repeat the contamination of coarse particles, and if the presence of coarse particles is attempted to be sufficiently reduced, the S value will become excessive.

The present invention takes into consideration the property E of wet grinding that p, 2+ < narrow spread of distribution, fully ascertains what range the S value should be in, and determines to what extent wet grinding should be carried out. Clarify the conditions under which such
The object of the present invention is to provide a water-based paint containing pure calcium carbonate as a pigment, giving an S value in an appropriate range and comprehensively improving the above-mentioned d# properties.

The calcium carbonate according to the present invention is wet-milled, and is given by the above formula (C) after wet-milling.

Ru S+! However, when the S value after wet grinding is expressed as S1 below, θ4 Sl l;, ? , θ...
...8) It falls within the range given by equation (3) above.

If wet grinding is carried out, coarse particles, for example, particles with a large diameter that fall into the 77th class, will be finely ground, and at the same time, the particle size distribution will be narrowed, that is, particles in the 1st/class will not exist or will be present. Also, the amount of Si is extremely small9.
There is no possibility that the t-shift becomes large. In wet grinding, if
This is because the tendency for materials with a high R-class to be destroyed quickly is significantly stronger than that of materials that are dry-milled.

The degree of li-grinding is also important. For example, when the S value of conventional calcium carbonate obtained by dry mechanically crushing limestone is calculated based on the above table (the S value before wet crushing is hereinafter expressed as So), the So value is based on the formula G31. Even if there are people in the area, it cannot be said that the amount of coarse particles is small. With the product of the present invention, when S>=93, it is possible to obtain a high quality paint, but with the mechanical dry grinding product, even if the So value is ζj, the paint of class 1/7.1 can be obtained. Many of these substances are mixed together, and its performance as a paint is extremely poor. Therefore, even those that are dry-ground must be wet-ground again at least once. Although wet pulverization is absolutely necessary, the degree of wet pulverization is extremely important. The IW value is calculated by the following formula (
4) is given by

St'hv'So2+a,,
,,, (4) Generally, since So/:Sl, S,= 5, , , , , (5),
In general, a>θ is always satisfied. This a may be given by a function of So, but if 6\j is used, a single VC is sufficient, and more preferably α≧70−C.

(3) and (4), horizontal axis is 80%, inertial axis 1kSX
When shown in a graph as , the product of the present invention belongs to the cross-hatched area in FIG. The area below the vertical gland of So = SL shown by 7 points and 4 lines cannot be considered as a general V, but E < S.

〈Even in the case of 9, there are still coarse particles F in the wet-pulverized calcium carbonate powder in the area A between the curved line and the straight line j.
Since the pulverization with respect to Vc is insufficient, there is a large amount of coarse particles mixed in, and the paint is not of good quality.

Therefore, for various values of So, S = j
Divide the range from Sz = ri into several stages, obtain the value of a in formula (5) as an actual measurement value that will give you the best quality paint, and then calculate the value of a in formula (5) at that value a. It is convenient for implementation if the wet pulverization conditions for obtaining Sy- are determined.

As mentioned above, if the Si value that satisfies equation (4) cannot be obtained after being wet-pulverized, there is a possibility that large amounts of coarse particles are mixed in.9 Therefore,
In this case, it must be wet-pulverized again, but no matter how many times it is wet-pulverized, the S value obtained by the last wet-pulverization is iSi, and s tt is SO when it has not been wet-pulverized seven times. As such, equation (4) is applied.

For wet pulverization, a pulverizer such as a ball mill or a sand mill is used. For example, a multi-leaf crushing impeller attached to the rotating shaft is rotated in the casing 3, and limestone and water, which have been made into small particles from the intake log, are sieved with a slit plate or a gold plate. Take it out from outlet 6. The S value after wet milling thus extracted is represented by 81, and the one introduced from the intake log, when it has never been wet milled, is represented by So.

Water-based materials using rutinous calcium carbonate, which has an S value that satisfies formula (3) obtained by wet grinding, are comprehensively superior in properties such as gloss, hiding properties, and weather resistance of the coating film. It is also of good quality, does not increase its viscosity over time, has little foaming, has excellent consistency, and has good brush control during application.

However, if the S11 shift exceeds 9, the 5L
The larger III is, the finer the particles are, so the viscosity is already high at the time of paint creation.
During application, the il+IJ hair handling is lower than 1, and the abrasiveness is also reduced.

On the other hand, when the Sl value is less than j, it is the same as dry salt coal! Mimarube,
The physical properties of the concealing valley deteriorate, and it is only possible to use it as a mere filler.

Wet grinding may be carried out by simultaneously layering other pigments such as precipitated calcium carbonate, clay, and Merck in a suspension of heavy calcium carbonate; Since it is a crystal-like crystal and easily breaks, it is necessary to be careful about the mixing ratio of charcoal, etc. in practice.

In addition, when blending into water-based m-materials, it is actually necessary to increase the solid content of calcium carbonate slurry through a -C 9 sieve to increase the solid content of the paint, so polyacrylic #R is generally used as a pigment dispersant. It is best to add a layer or more of salt, phosphate, maleic anhydride copolymer, etc. to the aqueous suspension of returned calcium to lower the viscosity f of the suspension, and then perform wet pulverization. It's advantageous. The N-quality calcium carbonate slurry after pulverization is dehydrated as necessary due to transportation problems, etc., and the slurry is used after the solid content is 11 ft IQI.

The test items are reported below. Examples and comparative examples are listed below. In both Examples and Comparative Examples, the final paint performance was evaluated for two types of paint formulations as shown below.

[Paint formulation 1] PVC = Ko θ 0 mil pace water / θ θ heavy 1 part milling (Dai-Kogyo Seikei, Descoat N/DA) ♂ - Dispersant (, Neugen FA/, 2 θ) 2 # Antifreeze agent ( Propylene glycol) Ri θ I Titanium White (6 Hara Sangyo, R-63 θ) / Ri! I Teisu charcoal/Sicalcium (solid content 20% slurry) 73'- O let down mill pace emulsion (Dainippon Ink, Boncourt TD (12/
,,3-0chi) 672 layers 1 part ri'SII A
IJ (ethylene glycol-mono-N-butyl ether) 7θ I Protective colloid (HEC, 26% 5ol) 73 1P
H regulator (ammonium hydroxide, 2t% So/) 2
Heavy J Part [Paint Formulation 2] PVC = 4θ Thio Mill-based Dispersant (Instrument Kogyo Seiyaku, Tesco) N/Da)/Resalt Part Dispersant (I Neugen EA/20) I Antifreeze (Propylene Glycol) 2θ lfl calcium carbonate (solid content 1 ots slurry) 4too
'Titanium white (6 Hara Sangyo, R-630) 23θ IO fret-unmill base emulsion (Dainippon Ink, Bonko) 23/θ [acrylic styrene resin" 166%) /, 15'g gap film forming agent (ethylene Glycol-mono-N-butyl ether) 30' Protective colloid (llEC, 2J96 Sol)
tθ Higashidaibe P H, J! Powder (ammonium hydroxide, 2
3%5ol) 3 #Repentance-/5o=-2, 700 parts of male heavy calcium carbonate and 42 parts of sodium polyacrylate as a dispersant were suspended in water to a solid content concentration of 7θ, and Create a suspension using a disper stirrer (Tokushu Kikaku) and add this to Dynoco Mill (W
Wet pulverization was performed using a pr-LOT type (manufactured by AB Company) so that S2=Jj. Using the thus obtained heavy calcium carbonate, water-based paint compositions were prepared according to the above paint formulations 1 and 2, and the paint performance was evaluated.

The results obtained are shown in the table.

Example - Using 700 parts of essential calcium carbonate with So = λθ and 43 parts of sodium polyacrylate as a dispersant, a suspension was prepared as in the actual sister example, and it was made into S Yo-Pe 3 using Guino Mill. Wet grinding was performed, and the heavy calcium carbonate was prepared into a water-based paint composition using the above paint formulations 1 and λ, and the paint performance was evaluated.

The results obtained are shown in the table.

Example-3 100 parts of heavy calcium carbonate with S0=22 and 4 parts of sodium polyacrylate as a dispersant. A portion was suspended as in Examples 1 and 2 and wet milled to give Sx = 7 g. Such heavy calcium carbonate is added to the above paint formulations 1 and 2.
A water-based paint composition was prepared and the paint performance was evaluated.

The results obtained are shown in the table.

Example - Heavy calcium carbonate with DaSo = 21 at a solid concentration of 33
% using a water-hydration lab body spar stirrer, wet-grinding using a sand grinder mill (Igarashi Kikai Seizo Co., Ltd., model G) until Sz = tj, and then suspending the heavy calcium carbonate using a hydraulic manual press ( After dehydration to a solid content concentration of 2θ1 at Shindo Metal Industry Co., Ltd., 2θ parts of sodium polyacrylate was added to 10θ parts of heavy calcium carbonate solid content, and the mixture was slurried using a laboratory spar. Water-based paint compositions were prepared from the thus obtained heavy calcium carbonate using paint formulations 1 and 2, and the paint performance was evaluated.

The results obtained are shown in the table.

Example - 100 parts of heavy calcium carbonate of 5 o = 40 and 43 parts of sodium polyacrylate as a dispersant were suspended in water to a solid content concentration of 70%, and mixed with a lab body spar stirrer for +s
Create a llklg and use a dyno mill to make S z
Wet pulverization was carried out so that the particle size was 60. A water-based paint was prepared using the 20% solid content aqueous suspension of heavy calcium carbonate according to the above paint formulations 1 and 2, and the paint performance was evaluated. The results obtained are shown in the table.

Even when the above-prepared heavy calcium carbonate was measured using a grindmeter (thick (right-handed, 10θU corner type)), no coarse particles larger than 〃μ〃μ were found.

Example-6 Using 100 parts of heavy calcium carbonate with s0 = 40 and 43 parts of sodium polyacrylate as a dispersant, a suspension was prepared as in Example-j and wet-pulverized to obtain Ss = B, θ.
And so. Water-based paints were prepared using the 70% solid content aqueous suspension of heavy calcium carbonate according to the paint formulations 1 and 2 above, and the paint performance was evaluated.

The results obtained are shown in the table.

In addition, even when the nine-dimensional calcium carbonate prepared above was measured using a grindmeter (Model θ~1100tt* manufactured by Taiyu Kikai Co., Ltd.), no coarse particles beyond the μ corner were observed.

Comparative Example-7 so=x 4t of heavy calcium carbonate t-Example-Gnoto <S> =9. The water-based paint compositions were prepared using paint formulations 1 and 2, and the paint performance was evaluated.

The results obtained are shown in the table.

Comparative Example - Heavy calcium carbonate 7 by dry grinding 1 classification with S=jθ
00 parts, 47 parts of sodium polyacrylate as a dispersant
Aqueous paint compositions were prepared using paint formulations 1 and 2, and the paint performance was evaluated.

The results obtained are shown in the table.

Comparative Example 3 Using precipitated calcium carbonate produced by a chemical reaction, a water-based paint composition was adjusted to A4 according to Paint Formulation 1, and the paint performance was evaluated. However, in paint formulation 2, due to its high viscosity, it became pudding-like, and other paint properties could not be evaluated.

The results obtained are shown in the table.

Comparative example - S by elutriation in the laboratory. -Create 700 parts of lucium with a carbonation capacity of -3.0 and add it to water with 3 parts of polyacrylic acid to give a solid content of 7θ, and make a suspension using a laboratory spar. Create nine. Using this heavy calcium carbonate slurry, paint performance was evaluated using the paint formulations 1 and 2 above.

Furthermore, the thus obtained heavy calcium carbonate contains coarse particles of about 30 micron vortices when measured with a grind meter.

Comparative example-! Heavy calcium carbonate (5
Wet pulverization was performed using 700 parts of O=j; 7) and 43 parts of sodium polyacrylate as a dispersant until SL=B and θ. Other conditions are the same.

(Coarse particles of 20 figs or more are mixed in.) Comparative Example-6 Heavy calcium carbonate of So=2〇 was wet-pulverized to Sz=Dagu. Other conditions are the same, (XTP coarse particles larger than Nawate are mixed.
7 So=4. θ heavy calcium carbonate is made into a slurry. The song conditions are the same as in the comparative example.

(Coarse particles of 30 μm or more.) Paint test results for paint formulation 1 Paint test results for paint formulation 2 Viscosity BM type viscosity meter 3 and A' grouter 40r
Measure the 0C value of pm Gloss Finished paint with 4 (rnie doctor brake)
2cPc applied to a glass plate with a 2-day stand.Weather resistance Weather tester/θ♂min carbon arc, 7
Measure the gloss after 200 hours under the conditions of 2-minute shower coating temperature jyjθ0C, and display according to the initial value retention rate. Display concealment rate: Put the finished paint on concealment rate test paper TlC2m1
Measure the whiteness of the black background and the whiteness of the white background after coating with a Z doctor blade and drying. Can the performance of water-based paints be improved by blending ground heavy calcium carbonate into water-based paint compositions? I can do that.

[Brief explanation of drawings]

FIG. 7 is a graph showing the relationship between %so 1-t and Sl value as shown in FIG. 1, and FIG. 2 is a sectional view showing a specific apparatus for the wet grinding method. (゛、Male E

Claims (1)

[Claims] Semi-average particle diameter D1 (However, all particles are divided into 77 classes according to diameter, and the center of the particle diameter of each class is indicated by di x 10-' m, and 4
7 class medium heat 1 direct d1, dl-(θ1Qg)/ko*/
Q"' ms 2nd pie Gl center: 1d2f, d
2=(4g-1-4j)/-2・/θ-6 class, the median value d3, ``4'' for each of Tatsuji, 3rd grade, Z1 young grade 1601, 1st θ:)6 grade, ,,%'no−
ds=0.36, d4=(263s da=(27
K, de=09, dma=1, de=23% d9
= 3. j s 'so = bej1, and all particles with a particle diameter of formula 0 or more are uniformly dz as 411 class.
It is calculated by using the following formula (1) using the value of z = 9 (single f of particle ff, r is lθ), and the weight of each class is indicated by w5) S1 direct is the following formula (2) U θ I S Otsu 2
θ...The S basket, that is, the So value when it has been wet-milled to be within the range shown in (2) and has never been wet-milled, is calculated by the following formula (
3) It is determined by the % formula % (3), and the particle size of the above-mentioned calculation is determined by the wet grinding of the calcium carbonate. Each sample after crushing,
Sodium hegisametaphosphate 42 mu aS water solution, 4 for the water solution! ~λ**S and shaking for io minutes, and then containing the water-based paint as an additive.