JP5827557B2 - Aqueous paint composition - Google Patents

Description

  The present invention relates to an aqueous paint composition, and more particularly, to an aqueous paint composition that is not discolored over time and has excellent drawing properties.

  The aqueous paint composition is generally an aqueous paste-like pigment composition for drawing coloring, which is obtained by kneading a color pigment, a water-soluble resin, a wetting agent and water together with an extender pigment, a surfactant or the like, if necessary. It is. In the water-based paint composition, the water-soluble resin, which is also called a paste, is blended as a color pigment fixing agent and a color developing agent. Conventionally, dextrin is often used from the viewpoint of supply stability and cost. ing.

  However, it is known that an aqueous solution of dextrin turns brown over time, that is, browning occurs. Therefore, an aqueous paint composition, which is an aqueous composition containing dextrin, is similarly changed over time. It is known to cause browning. In particular, an aqueous paint composition often contains an alkaline substance such as calcium carbonate as an extender, and dextrin can be more easily browned in the presence of such an alkaline substance. Are known. That is, an aqueous paint composition containing dextrin as a water-soluble resin and an alkaline substance such as calcium carbonate as an extender pigment easily browns over time.

  Therefore, an aqueous paint composition containing dextrin as a water-soluble resin is a dextrin as described above, particularly when a white or light-colored pigment or a highly saturated color pigment such as a yellow pigment or an orange pigment is used. There is a problem of discoloration based on browning over time. In the case of a paint composition using a dark or black color pigment, the color composition of the color pigment itself is strong, and even if the dextrin browns over time, the color composition is hardly affected. A coloring pigment having a relatively large color development due to the browning of dextrin, that is, the above-described white to light-light pigment, or a high-saturation coloring pigment such as a yellow pigment or an orange pigment was used. Based on the browning of dextrin over time, the paint composition also changes color over time and does not give the original color when drawing.

  Accordingly, in order to solve such problems, it has been proposed to prevent discoloration over time in the aqueous paint composition by blending a solid acid into the aqueous paint composition blended with dextrin (Patent Document). 1).

  In such an aqueous paint composition, when the color pigment used is a light-colored color pigment containing white, discoloration with time is effectively prevented, but other than the absorbent drawing surface such as paper. Styrene-acrylic acid resin alkali salt as a wetting agent in an aqueous paint composition so that it can be drawn on a drawing surface, for example, a drawing surface made of resin, glass, metal, etc., for example, the surface of a synthetic resin container such as a plastic bottle In order to contain the above wetting agent as an alkali salt, the aqueous paint composition must be alkaline even if it contains a solid acid. The aqueous paint composition still undergoes discoloration over time.

JP 2005-247975 A

  The present invention has been made in order to solve the above-described problems in conventional aqueous paint compositions using dextrin as a water-soluble resin, and is free from discoloration over time and has excellent drawing properties. An object is to provide a composition.

  In particular, the present invention contains an alkaline extender pigment such as calcium carbonate and an alkaline wetting agent such as a styrene-acrylic acid resin alkali salt or a styrene-maleic acid resin alkali salt, and the pH is in the alkaline region. Even if it exists, it aims at providing the aqueous | water-based paint composition which does not change with time.

  An aqueous paint composition according to the present invention is an aqueous paint composition containing a color pigment, a water-soluble resin, a wetting agent, and water, characterized in that it contains a reduced dextrin as the water-soluble resin.

  The water-based paint composition according to the present invention contains reduced dextrin instead of dextrin as a water-soluble resin, has no color change over time, and is excellent in drawability.

  In particular, the aqueous paint composition according to the present invention contains an alkaline extender pigment such as calcium carbonate, and an alkaline wetting agent such as a styrene-acrylic acid resin alkali salt or a styrene-maleic acid resin alkali salt. Even when the pH is in the alkaline region, discoloration over time does not occur.

  The aqueous paint composition according to the present invention includes a reduced dextrin as the water-soluble resin in the aqueous paint composition containing a color pigment, a water-soluble resin, a wetting agent, and water.

  In the present invention, the color pigment has a function as a colorant, and any of those conventionally known as such colorants in an aqueous paint composition can be used.

  However, as described above, when a dextrin is used as a water-soluble resin in an aqueous paint composition using a white pigment or a light-colored color pigment or a high chroma pigment, for example, a yellow pigment or an orange pigment, as the color pigment, Where time-dependent discoloration occurs based on time-dependent browning, according to the present invention, such time-dependent discoloration can be prevented by using reduced dextrin instead of dextrin.

  According to the present invention, specific examples of such white to light-colored color pigments include at least one selected from titanium oxide, zinc oxide, zinc sulfide, and lithopone. Specific examples of yellow pigments include at least one selected from azo yellow pigments, pyrazolone yellow pigments, quinophthalone yellow pigments, flavantron yellow pigments, cadmium yellow, cobalt yellow and titanium yellow. In addition, specific examples of the orange pigment include at least one selected from an azo orange pigment and an anthraquino orange pigment.

  In particular, according to the present invention, even when a white pigment such as titanium oxide, zinc oxide, zinc sulfide or lithopone is used, discoloration with time does not occur when reduced dextrin is used as the water-soluble resin. In particular, in the present invention, titanium oxide is preferably used as the color pigment.

  In the present invention, such a color pigment is usually used in the range of 5 to 50% by weight, preferably 10 to 40% by weight, in the aqueous paint composition.

  In the aqueous paint composition, when the blending ratio of the color pigment is too large, the viscosity of the resulting aqueous paint composition becomes excessively high and the elongation becomes poor. However, when the blending ratio of the color pigment is too small, the resulting aqueous paint composition has poor coloring power and cannot be used as a paint.

  According to the present invention, together with the colored pigment, extender pigments such as barium sulfate, barium carbonate, calcium carbonate, calcium sulfate, alumina white, clay containing bentonite, hydrous silicic acid, and anhydrous silicic acid are used. The extender pigment is usually used in the range of 3 to 50% by weight, preferably 5 to 40% by weight in the aqueous paint composition.

  Since the aqueous paint composition according to the present invention uses reduced dextrin as a water-soluble resin, it does not cause browning over time. In particular, according to the present invention, even if an alkaline pigment such as calcium carbonate is used as the extender pigment, the resulting aqueous paint composition does not brown over time. As in the case of the color pigment, in the aqueous paint composition, when the proportion of the extender pigment is too large, the resulting aqueous paint composition has an excessively high viscosity and poor elongation.

  In the present invention, the wetting agent is used to optimally adjust the drying property of the aqueous paint composition, and is used as an antifreezing or resolubility improver. Specific examples thereof include, for example, glycerin and ethylene glycol. Polyhydric alcohols and glycols such as propylene glycol, dipropylene glycol and sorbitol are preferably used.

  The humectant is preferably used in the aqueous paint composition in the range of 1 to 25% by weight, particularly 2 to 15% by weight. When the blending ratio of the wetting agent is too large, the coating film of the obtained aqueous paint composition is difficult to dry and unusable. However, when the mixing ratio of the wetting agent is too small, when the coating film of the obtained aqueous paint composition is dried, it is brittle and easily cracks.

  In the aqueous paint composition according to the present invention, reduced dextrin is used as a water-soluble resin, that is, a paste. By using reduced dextrin instead of dextrin, as described above, even when a white or light-colored pigment or a high chroma pigment, such as a yellow pigment or an orange pigment, is used as a coloring pigment, discoloration over time does not occur. . In particular, even when a white pigment such as titanium oxide, zinc oxide, zinc sulfide or lithopone is used, discoloration over time does not occur when reduced dextrin is used as the water-soluble resin.

  The reduced dextrin is one of sugar alcohols obtained by hydrogenating and reducing the carbonyl group of dextrin (for example, JP-A-5-214002), and for example, H- produced by Matsutani Chemical Co., Ltd. Commercial products such as PDX can be used.

  The reduced dextrin is usually used in an aqueous paint composition in an amount of 3 to 40% by weight, preferably 5 to 30% by weight, and most preferably 8 to 28% by weight. When the ratio of the reduced dextrin in the aqueous paint composition is too large, the coloring power of the resulting aqueous paint composition becomes weak, and the coating film becomes glossy. On the other hand, when the ratio is too small, the fixability of the obtained aqueous paint composition on the drawing surface is deteriorated.

  In the present invention, a second water-soluble resin may be used together with the reduced dextrin as necessary. However, dextrin is excluded. The second water-soluble resin is not particularly limited, but includes gum arabic, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, styrene-acrylic acid resin alkali salt, styrene-maleic acid resin alkali. A salt or the like is preferably used.

  However, among these second water-soluble resins, by using at least one selected from gum arabic, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose, it is easy to stretch at the time of drawing. An aqueous paint composition can be obtained. These second water-soluble resins are used in the paint composition, preferably in the range of 10% by weight or less, and preferably in the range of 1 to 5% by weight.

  On the other hand, by using at least one selected from styrene-acrylic acid resin alkali salt and styrene-maleic acid resin alkali salt as the second water-soluble resin, a drawing surface other than an absorbent drawing surface such as paper, For example, an aqueous paint composition that can be well drawn on a drawing surface made of resin, glass, metal or the like, typically on the surface of a synthetic resin container such as a so-called PET bottle can be obtained. These second water-soluble resins are used in the paint composition, preferably in the range of 10% by weight or less, and preferably in the range of 1 to 5% by weight. As the alkali salt, an alkali metal salt, an amine salt or an ammonium salt is usually used.

  Of course, in the present invention, as the water-soluble resin, at least one selected from gum arabic, carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl cellulose, styrene-acrylic acid resin alkali salt and styrene-maleic acid resin alkali It is also a preferred embodiment to use at least one selected from salts in combination.

  In the aqueous paint composition, when the ratio of the second water-soluble resin is too large, the coloring ability of the obtained aqueous paint composition becomes weak and the coating film has gloss. On the other hand, when the ratio is too small, the fixability of the obtained aqueous paint composition on the drawing surface is deteriorated.

  When the aqueous paint composition according to the present invention contains calcium carbonate as an extender and / or contains at least one selected from styrene-acrylic acid resin alkali salt and styrene-maleic acid resin alkali salt as a wetting agent, The pH is in the alkaline region, that is, in the range of more than 7 to 11 or less, preferably in the range of 7.5 to 11, particularly preferably in the range of 7.5 to 8.5.

  The aqueous paint composition according to the present invention may contain a surfactant as necessary in order to enhance the dispersibility of the pigment and enhance the storage stability of the paint composition. Further, as described above, for example, when used for drawing on the surface of a PET bottle, a surfactant may be included in order to prevent the paint from being repelled on the surface of the PET bottle. As the surfactant, an anionic surfactant and a nonionic surfactant are used alone or in combination. Silicone surfactants are also used.

  When the surfactant is blended in the aqueous paint composition, it is usually blended in the range of 0.01 to 10% by weight, preferably in the range of 0.1 to 5% by weight in the paint composition. . When the ratio of the surfactant in the paint composition is too large, the paint is likely to penetrate excessively into an absorbent drawing surface such as paper, resulting in poor elongation.

  In the present invention, water serves as a solvent or a dispersion medium in the aqueous paint composition, and is usually used in the range of 15 to 55% by weight, preferably 20 to 45% by weight in the aqueous paint composition. . When the ratio of water as the solvent or dispersion medium is too large, the viscosity of the resulting aqueous paint composition becomes excessively low and the pigment is separated, resulting in poor storage stability, while the ratio of water When there is too little, the said water-soluble resin does not fully melt | dissolve, but the viscosity of the obtained aqueous paint composition is high, and elongation becomes bad.

  The aqueous paint composition by this invention is not specifically limited in the manufacturing method, For example, it can obtain by the following methods. That is, a water-soluble resin is dissolved in water, and a color pigment and a wetting agent are added to the obtained aqueous solution, and if necessary, an extender pigment, a surfactant, an antiseptic / antifungal agent, water, and the like are added and mixed uniformly. What is necessary is just to knead | mix the obtained mixture further by appropriate means, such as a roll mill, stirring.

  EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

Example 1
Reduced dextrin, carboxymethylcellulose, and styrene-acrylic acid resin sodium salt were each dissolved in water to give aqueous solutions. A titanium oxide pigment, a wetting agent and water were added to this aqueous solution and stirred to obtain a uniform mixture. This mixture was kneaded using a three-roll mill to obtain an aqueous paint composition.

Examples 2-4
An aqueous paint composition was obtained in the same manner as in Example 1 using the raw materials shown in Table 1.

Comparative Examples 1-3
An aqueous paint composition was obtained in the same manner as in Example 1 using the raw materials shown in Table 1.
Each aqueous paint composition thus obtained was examined for discoloration over time and elongation during drawing.

(PH of paint composition)
Using a simple pH meter Twin pH B-212 (manufactured by Horiba, Ltd.), the pH of the paint composition was measured as it was.

(Evaluation of browning over time)
Draw on the drawing paper using the aqueous paint composition stored for one month in a constant temperature bath at 50 ° C. Compared with the drawing drawn using the paint before storage, the coloration is different. When there was no discoloration, A was given, when some discoloration was observed, B, and when there was significant discoloration, C.

(Elongation)
The paint composition was placed in the size of red beans on one place on the drawing paper placed horizontally. The circular brush was made to stand vertically with sufficient water, and the paint composition was melted from the edge of the brush with the tip of the brush, and then the brush was carried in one direction while being applied zigzag to the drawing paper. At this time, lower the brush to the root at the vertical part where the paint composition was applied, and then apply the paint composition in one direction while applying the zigzag to the vertical and oblique parts where the paint composition was applied. The elongation of the paint composition was evaluated from the carrying of the brush and the remaining state of the drawing trace.

  If the paint composition does not stretch well, the brush will not slide smoothly, and the paint composition will be unevenly applied, so that the painted part will be drowned, leaving a trace of the brush tip of the paint brush . Therefore, when the paint composition stretches very well, it is A, and it is stretched, but when the trace of the brush tip remains somewhat, it is B, when it does not stretch at all and the trace of the brush tip remains, C. did. The results are shown in Table 1.

  Each raw material in Table 1 shows the following.

Titanium oxide pigment: Sakai Chemical Industry Co., Ltd. A-110P
Hydrous silicic acid: DSL. NO67 Carplex reduced dextrin manufactured by Japan Co., Ltd .: H-PDX manufactured by Matsutani Chemical
Carboxymethylcellulose: Serogen 7A manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
Styrene-acrylic acid resin sodium salt: Johnson polymer Johncrill 690 sodium salt dextrin: Matsutani Chemical Co., Ltd. British gum 70E

  As shown in Table 1, the aqueous paint compositions (Examples 1 to 4) according to the present invention containing calcium carbonate as an extender pigment and / or styrene-acrylic acid resin sodium salt as a wetting agent have an alkaline pH. Despite being in the region, since it contains reduced dextrin as a water-soluble resin (Examples 1 to 4), it not only has no discoloration over time but also has excellent elongation during drawing.

  On the other hand, the aqueous paint composition using the dextrin as the water-soluble resin (Comparative Examples 1 and 2) is markedly discolored over time. On the other hand, by using carboxymethylcellulose and styrene-acrylic acid resin sodium salt as a water-soluble resin instead of dextrin (Comparative Example 3), a paint composition that does not cause discoloration over time can be obtained. However, in this case, in order to obtain a transparent or translucent paint composition using carboxymethylcellulose and styrene-acrylic acid resin sodium salt as water-soluble resins, the blending amount thereof must be increased. And if the compounding quantity is increased, the resulting paint composition has a too high viscosity, and the elongation at the time of drawing deteriorates.

Claims (9)

In an aqueous paint composition containing a color pigment, a water-soluble resin, a wetting agent and water, the water-soluble resin contains a reduced dextrin, and as the second water-soluble resin, styrene-acrylic acid alkali salt and styrene-maleic acid An aqueous paint composition comprising at least one selected from resin alkali salts and / or calcium carbonate as an extender and having a pH in the range of 7.5 to 11 . In an aqueous paint composition containing a color pigment, a water-soluble resin, a wetting agent and water, the water-soluble resin contains a reduced dextrin, and as the second water-soluble resin, styrene-acrylic acid alkali salt and styrene-maleic acid The aqueous paint composition according to claim 1, comprising at least one selected from resin alkali salts and calcium carbonate as an extender pigment. The aqueous paint composition according to claim 1 or 2 , further comprising at least one selected from gum arabic, carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl cellulose as the second water-soluble resin. 3. The aqueous paint composition according to claim 1 or 2 , wherein the color pigment is a white or light-light pigment, a yellow pigment, or an orange pigment. The aqueous paint composition according to claim 4 , wherein the white to light-colored pigment is at least one selected from titanium oxide, zinc oxide, zinc sulfide and lithopone. 5. The aqueous paint composition according to claim 4 , wherein the yellow pigment is at least one selected from azo yellow pigments, pyrazolone yellow pigments, quinophthalone yellow pigments, flavantron yellow pigments, cadmium yellow, cobalt yellow and titanium yellow. . The aqueous paint composition according to claim 4 , wherein the orange pigment is at least one selected from an azo orange pigment and an anthraquino orange pigment. The aqueous paint composition according to claim 1 or 2 , wherein the color pigment is titanium oxide. The aqueous paint composition according to claim 1 or 2, wherein the wetting agent is glycerin.