JPS6037135B2 - aqueous composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aqueous composition suitable as an aqueous coating agent.

BACKGROUND ART It is widely practiced to apply a resin-based coating agent to paper or the like to impart gloss, water resistance, abrasion resistance, etc. Conventionally, solvent solution type coating agents were commonly used, but recently, from the viewpoints of resource saving, pollution prevention, safety, and hygiene,
Water-based coating agents have appeared. When a water-based coating agent is used, it is common that a hot press finish is further applied after coating. This is because if a resin with a low melting point is used to produce gloss, it will cause a fatal accident of blocking of the coated material during the coating process, and if a resin with a high melting point and good blocking resistance is used, the coated surface will Since this may cause cracks, etc., or the gloss is noticeably inferior, a resin coating agent with a high melting point is used, and after coating, hot pressing is performed to satisfy gloss and anti-blocking properties at the same time. . It may be possible to add aqueous solvents such as alcohol to these aqueous solution type coating agents to improve film forming properties and gloss, but this requires an extremely large amount of solvent and is practically no different from conventional solvent solution types. In addition to this, it is also difficult to increase the resin concentration, and it also has the disadvantage of inherently poor water resistance. On the other hand, emulsion type coatings inherently have a defect in film-forming properties, and due to the adverse effects of emulsifiers, the dried coating loses transparency and has an unsatisfactory luster.

Furthermore, in this case, it is almost impossible to improve the film-forming properties by adding an aqueous solvent because the stability of the emulsion is lost.
In view of the above, it is an object of the present invention to provide an aqueous composition which, when used as an aqueous coating agent, provides a satisfactory result without particularly requiring hot press finishing.

As a result of intensive research with the above object in mind, the present inventor has confirmed that the aqueous composition described in the claims satisfies the object of the present invention, and has accomplished the present invention.

In the present invention, the acrylic resin having a carboxyl group includes acrylic acid, methacrylic acid, maleic acid,
Copolymerization of ethylenically unsaturated acid monomers such as itaconic acid, acrylic acid esters, methacrylic acid esters, and, if desired, pinyl monostars such as styrene, methylstyrene, and hard acid pinyl, which are copolymerizable with these esters. Refers to union. Therefore, the appropriate proportion of the brewing ingredients in the above monomer composition depends on the amount of glycidyl acrylate, glycidyl methacrylate, etc. used in the next step, but is generally conveniently in the range of 5 to 25%.

In the present invention, a water-soluble ammonium and/or amine salt of a modified acrylic resin obtained by reacting the above-mentioned acrylic resin having a carboxyl group with glycidyl acrylate and/or glycidyl methacrylate is added to the vinyl monomer. Although used as a dispersion stabilizer, the amount of the glycidyl compound used is required to be 0.5 to 0.05 equivalent per equivalent of carboxyl group of the acrylic resin.

If the amount is less than this range, it will not be possible to achieve the purpose of the present invention, which is to make the dispersed particles of the resulting aqueous composition sufficiently fine to make the dried film of the composition transparent and impart sufficient gloss. If the amount exceeds this range, the solubility as a dispersion stabilizer will be poor, resulting in an unstable aqueous composition, and there is a risk of gelation occurring during polymerization. Further, the modified acrylic resin of the present invention requires a carboxyl group acid value of 20 to 150. If the acid value is less than 20, the resulting aqueous composition will lack stability, and if the acid value is greater than 150, the viscosity of the resulting aqueous composition will be too high, resulting in the formation of flies during polymerization. In addition to production difficulties, such as difficulty in production, the resulting dry film of the aqueous composition has defects in water resistance. In the present invention, by using such a specific dispersion stabilizer, emulsion particles obtained by emulsion polymerization are made into extremely fine particles, and sufficient stability is imparted to the aqueous composition of the present invention, and as a result, It is also possible to mix alcohol.

Even when the dry solid of the resulting aqueous composition has a high melting point, the film-forming properties are good and the film has sufficient gloss due to its fine particle nature, the action of the alcohol, and the structure of the resulting polymer. Furthermore, since a buccal alkali such as ammonia or amine is used to remove the dispersion stabilizer of the present invention, the water resistance of the dried film of the obtained aqueous composition is not impaired. In addition, while having the water resistance characteristic of emulsions, the uniformity of the composition is almost the same as that of an aqueous solution, and the transparency of the dried film is also excellent. As described above, the present invention uses an amine or ammonium salt of a modified acrylic resin with a specific molecular structure and a specific carboxyl group acid value as a dispersion stabilizer to carry out emulsion polymerization of vinyl monomers in a water-alcohol mixed solvent. It is something to do.

Emulsion polymerization of vinyl monomers in an aqueous medium using an amine salt or ammonium salt of a polymer having a carboxyl group as a dispersion stabilizer has already been widely carried out, but in this case, the emulsion particles are sufficiently finely divided. Therefore, the stability cannot be said to be sufficient, and the gloss of the dried film is extremely unsatisfactory, making it impossible to achieve the object of the present invention. Mochiseki Sho 50 Issho No. 592 discloses a method of carrying out emulsion polymerization of vinyl monomers in a non-aqueous solvent in the coexistence of wax and polyethylene.

However, the purpose of this case is different from that of the present invention, and therefore, it is completely impossible to apply the same dispersion stabilizer exemplified here to the present invention for the reasons detailed at the beginning. . In summary, the present invention carries out emulsion polymerization of vinyl monomers in a water-alcohol system using amine and ammonium salts of a modified acrylic resin with a specific molecular structure and a specific carpoxylic acid value as a dispersion stabilizer. This is the first attempt by the present inventor. The appropriate alcohol content in this mixed solvent varies depending on the melting point of the dry solid content of the resulting composition, but generally 20 to 60% is appropriate; if the alcohol content is too low, defects in film-forming properties will appear. . Also, as the alcohol that can be used here, any alcohol that is compatible with water can be used, but methanol, ethanol, inpropyl alcohol, n-propyl alcohol, ethyl cellosolve, inpropyl cellosolve, etc. are particularly preferred. . Examples of the polymerizable pinyl monomer to be subjected to emulsion polymerization in the present invention include acrylic esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, and 2-ethylhexyl acrylate; Methacrylate esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and stearyl methacrylate, aromatic vinyl monomers such as styrene and methylstyrene, hard-acid vinyl, vinyl propionate, etc. There are vinyl esters and the like, and monomers that can be radically copolymerized with these monomers can also be used in combination.

For the emulsion polymerization, conventional technical means can be used, and an oil-soluble radical polymerization initiator that is soluble in the monomers can also be used. The present invention can completely satisfy the object of the present invention by the technical means detailed above, and is not only excellent as a water-based coating agent, but also useful for water-based paints, water-based printing inks, and other paper and fiber coatings. It can be used for a wide range of purposes such as processing agents.

Specific examples of the present invention will be shown below, but these are not intended to limit the invention.

In the following examples, all parts and percentages indicated by Z are by weight. Example 1 20% of inpropyl alcohol was placed in a four-necked flask equipped with a rope, a thermometer, a nitrogen inlet tube, and a water bottle condenser.
Pour in the water and heat on a water bath to 800 ml while passing nitrogen gas.

While maintaining this state, styrene 90 times, methyl methacrylate 58 times, 2-ethylhexyl acrylate 10 times
Then, a mixture of 42 parts of methacrylic acid and 4 parts of azobisisobutyronitrile was added dropwise over 3 hours. After the dropwise addition was completed, the temperature was kept at the same temperature for 2 hours, 0.4 hours of azobisisobutyronitrile was added, and the temperature was kept for another 2 hours. Add 0.4 ml of azobisisobutyronitrile again and keep warm for 4 hours to complete polymerization. Subsequently, the contents were cooled and heated to 45
Dimethylaminoethanol 329, 25% at a temperature of oo
Add 7.8 hours of ammonia water and 135 minutes of water to dissolve.
To this, 366 mm of a mixed solvent consisting of 1 part of inpropyl alcohol/1 part of water and 6.95 mm of glycidyl methacrylate (0.1 equivalent to 1 equivalent of methacrylic acid) were added, the temperature was raised again, and the reaction was carried out at 80° C. for 4 hours. let The solution containing the dispersion stabilizer of the present invention obtained here (11', non-volatile content: 24.
It was a colorless and transparent solution with a concentration of 5% and a weight of 9.0%. (Note that the acid decomposition product of the dispersion stabilizer of the present invention has a carboxyl acid value of 119
It has the following. ) The solution containing the dispersion stabilizer of the present invention produced as described above (1) 165 quarts was charged into a 500' four-bottom flask equipped with the same equipment as above and heated to 65 quarts while passing nitrogen gas.

Next, styrene 12 days, methyl methacrylate 6.5 days
After that, a mixture of 17.59 g of 2-ethylhexyl acrylate and 0.36 g of azobisisobutyronitrile was added dropwise over 3 portions. After that, the mixture was polymerized at the same temperature for 3 hours, and then 0.036 mm of ammonium persulfate was added to the mixture to raise the temperature to 7yo, and the temperature was further kept for 3 hours to complete the polymerization. The resulting emulsion was an extremely stable dispersion with a particle size of approximately 4% inpropyl alcohol content in the dispersion medium, a non-volatile content of 34.8%, and a viscosity of 21 ps. When this was coated on a glass plate at a wet film thickness of 7, it showed excellent film forming properties and transparency using a bar coater M. When No. 8 was applied onto a printed paper surface, both gloss and blocking resistance were very good.
Comparative Example 1 In the manufacturing process of dispersion stabilizer solution '1' in Example 1, Example 1 was prepared without reacting glycidyl methacrylate.
This was repeated to synthesize an emulsion.

The obtained emulsion had a large particle size with an inpropyl alcohol content of about 54%, a nonvolatile content of 31.7%, and a viscosity of 13 Kps. When this was applied on a glass plate using the same machine, the film forming properties were good, but the coating became slightly white and cloudy, and when it was applied on a printed paper, the gloss was significantly poor and the blocking resistance was insufficient. Comparative Example 2 Dispersion stabilizer solution in Example 1 [In the manufacturing process of 11, glycidyl methacrylate 422 (0.6 equivalents per 1 equivalent of methacrylic acid) was reacted and Example 1 was repeated to synthesize an emulsion. As a result, the gel was removed in 30 minutes after the addition of Mo/Mer was completed.

Comparative Example 3 In the manufacturing process of dispersion stabilizer solution '1' in Example 1, glycidyl methacrylate 2.1 (
Example 1 was repeated by reacting 0.03 equivalents per 1 equivalent of methacrylic acid to synthesize an emulsion.

The resulting emulsion had an inpropyl alcohol content of 5
4%, non-volatile content: $35%, viscosity: 17&ps, and had a large particle diameter. When this was coated on a printed paper surface, both gloss and blocking resistance were significantly inferior to those of Example 1. Example 2 Into a four-necked flask similar to Example 1, 200 g of inpropyl alcohol was charged and heated to 8 g while passing nitrogen gas.
Heat to 0qC.

Next, 10 days of styrene, 1 day of methyl methacrylate,
A mixture consisting of 10 parts of 2-ethylhexyl acrylate, 12 parts of methacrylic acid, and 4 parts of azobisisobutyronitrile was added dropwise over 3 hours. After holding at this temperature for 2 hours,
Add 0.4 hours of azobisisobutyronitrile for 2 hours, then add 0.4 hours of azobisisobutyronitrile and keep warm for 4 hours to complete polymerization. After cooling to 45°C, 12 hours of dimethylaminoethanol and 165 hours of water were added to dissolve.

Add to this a mixed solvent of 1 part of inpropyl alcohol/1 part of water, 366 ml of a mixed solvent, and 6.25 ml of glycidyl acrylate (
0.35 equivalents per 1 equivalent of methacrylic acid) was added thereto, and the temperature was raised again to react at 8,000 ℃ for 4 hours. The obtained solution (2) containing the dispersion stabilizer of the present invention had a non-volatile content of 24.7%, p
It was a low viscosity solution of H87. The acid decomposition product of the dispersion stabilizer of the present invention had a carboxyl group acid value of 25. The solution containing the dispersion stabilizer of the present invention prepared by the above procedure was charged into a 500' four-necked flask equipped with the same equipment and heated to 65° C. under a nitrogen stream.

Next, styrene 12 days, methyl methacrylate 6.5 days
After that, a mixture of 17.5 mm of 2-ethylhexyl acrylate and 0.36 mm of azobisisoputilonitrile was added dropwise over 3 hours. After completing the dropping, maintain the temperature for 3 hours,
Add 0.036 g of ammonium persulfate and raise the temperature to 75
Polymerize at 0 for 3 hours. The obtained emulsion was a stable emulsion with a non-volatile content of 34.6%, a viscosity of 471 cps, and extremely small particle size. When this was coated on a glass slope and on a printed paper by the same means as in Example 1, it had very good film forming properties, transparency, gloss, and anti-blocking properties. Comparative Example 4 In the manufacturing process of dispersion stabilizer solution (2) in Example 2, 10.7 g of glycidyl acrylate (10.7 g of methacrylic acid)
When Example 2 was repeated using a modified acrylic resin synthesized by reacting 0.6 equivalents) as a dispersion stabilizer, 3. The system significantly thickened and showed a tendency to gel at Asa-dera.

Example 3 160 g of inpropyl alcohol was charged in a four-bottom flask similar to that in Example 1, and the mixture was heated for 8 g while introducing nitrogen gas.
Heat to 0.

Then, styrene 8, methyl methacrylate 1264
Then, a mixture of 8 parts of 2-ethylhexyl acrylate, 17.6 parts of methacrylic acid, and 3.2 parts of azobisisobutyronitrile was added dropwise over 3 hours. After polymerizing for 2 hours at the same temperature, 0.32 g of azobisisobutyronitrile was added and polymerization was further continued for 2 hours. After adding 0.32 g of azobisisobutyronitrile again, the temperature was maintained for 4 hours,
Complete polymerization. To this was added 35.4 g of a 50% solution of inpropyl alcohol of a commercially available rosin-modified maleic acid resin (trade name: Viros M-231 manufactured by Seiko Kagaku Kogyo), and the mixture was thoroughly mixed. This was cooled and dimethylamine/ethanol was added for 14.5 nights, 25% ammonia water for 6 nights, and water for 1 hour at 45q0.
Add 30 minutes to dissolve. Subsequently, 328 g of a mixed solvent consisting of 1 part of inpropyl alcohol/1 part of water and 5.82 g of glycidyl methacrylate (0.2 equivalents per 1 equivalent of methacrylic acid) were added, and the mixture was heated to 80°C and reacted for 4 hours. The solution paste containing the dispersion stabilizer of the present invention obtained here was a pale yellow, transparent, and low viscosity solution with a nonvolatile content of 23.4% and mottling of 9.0%. The acid decomposition product of the dispersion stabilizer of the present invention has a carboxyl group acid value of 60. Solution '3' containing the dispersion stabilizer of the present invention produced as above
Example 1 was repeated using 165 mm.

The obtained emulsion had a non-volatile content of 35.1% and a viscosity of 25.
This is a stable emulsion with an extremely small particle size of PS, and when it was coated on a glass plate and a printed paper surface, it was fully satisfactory in terms of film-forming properties, transparency, gloss, and anti-blocking properties. Examples 4 to 9 Various emulsions were synthesized using the dispersion stabilizer solution '1} according to the procedure of Example 1. No. 8 was coated and its gloss and blocking resistance were evaluated.

The results are shown in the table below. Table 1

Claims (1)

[Claims] 1 0.5 to 0 per equivalent of the carboxyl group of the acrylic resin to the acrylic resin having a carboxyl group.
．． Ammonium salt and/or amine salt of a modified acrylic resin having a carboxyl group acid value of 20 to 150 obtained by reacting 0.5 equivalents of glycidyl acrylate and/or glycidyl methacrylate are used as a dispersion stabilizer in a water-alcohol mixed medium. An aqueous composition obtained by emulsion polymerization of a polymerizable vinyl monomer.