JPH0128068B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aqueous composition containing a novel polyurethane resin, and more particularly to an aqueous composition containing a water-dispersible polyurethane resin containing a rosin skeleton in its side chain. be. In the field of coating agents, paints, and other coating agents or adhesives used for surface treatment of molded products, there are problems such as air pollution due to volatilization of organic solvents, deterioration of the working environment, and the risk of fire outbreaks. From a resource perspective, solvent-based coatings that use organic solvents as dispersion media are
One of the important issues is the so-called aqueous conversion to aqueous coatings using water or an aqueous medium. When making a coating aqueous, it is necessary to develop an excellent water-dilutable vehicle, and in particular, an aqueous coating composition using such a water-dilutable vehicle is quick drying and has good adhesion to the coating substrate. It is required to be in good condition. Aqueous coating compositions use water as the main dispersion medium, and because water has a large latent heat of vaporization, they inevitably have lower drying properties than solvent-based coatings that use organic solvents. . or,
Since the surface tension of water is high, it has poor wetting ability, especially on substrates having hydrophobic surfaces, and cannot provide sufficient adhesion. In particular, the present situation is that there are almost no aqueous coating compositions to be applied to plastic films or plastic molded articles having non-absorbent hydrophobic surfaces that can be bonded. Water-based polyurethane resin, which is the resin component of vehicles that has traditionally been thought to provide excellent adhesion to various base materials, has been actively studied and many proposals have been made, but there are still Aqueous compositions with sufficiently satisfactory adhesion to hydrophobic surfaces have not been obtained. In view of the current situation, the present inventors aimed to obtain an aqueous composition capable of adhering well to hydrophobic surfaces, especially non-absorbent hydrophobic surfaces such as plastic films, using a water dispersion as a vehicle component. As a result of extensive research into polyurethane resins, the inventors discovered that polyurethane resins in which a rosin skeleton was introduced into the side chain portion could satisfy the above objectives, and based on this, the present invention was completed. That is, the present invention provides a polyurethane resin obtained by reacting an organic polyisocyanate compound and a polyol compound at an equivalent ratio of NCO:OH=1:0.8 to 1.5, the polyurethane resin comprising: (a) rosin and trivalent Diol compound which is an esterification reaction product with alcohol 50-80% by weight (b) Aliphatic diol compound containing a basic tertiary nitrogen atom 20-50% by weight (c) Other polyol compound 0-30% by weight It is an aqueous composition consisting of a polyurethane resin [A], an acidic substance [B], and an aqueous medium [C], and the content of [A] is 1 to 50% based on the weight of the composition.
It relates to an aqueous composition in which the content of [B] is 0.8 to 1.5 equivalents per equivalent of tertiary nitrogen atom in [A], and the remainder is [C]. The aqueous composition of the present invention is obtained by dispersing and dissolving a polyurethane resin containing a rosin skeleton as a side chain and a basic tertiary nitrogen atom in an aqueous medium by forming a salt with an acidic substance. . Until now, there have been almost no attempts to introduce a rosin skeleton as a side chain in a polymer chain. An example of the use of rosin in polyurethane resins is the use of rosin in the form of a polyester polyol whose polycarboxylic acid component is an addition reaction product of Diels-Alder reaction between rosin and α/β-unsaturated carboxylic acid (Japanese Patent Application Laid-Open No. No. 54-143306), but in this case, the rosin skeleton is incorporated into the main chain, and the rosin skeleton has already been modified by the addition of an α/β-unsaturated carboxylic acid. Therefore, even if an aqueous coating composition containing such a water-dispersible polyurethane resin is used, adhesion to a hydrophobic surface is extremely poor, and this polyurethane resin has poor water-dispersibility. It has the serious drawback that it cannot be dispersed in water unless a sufficient amount of alcohol is used. In order to introduce a rosin skeleton into the side chain of a polyurethane resin, the reaction of the carboxyl group of the resin acid in the rosin is utilized. In the present invention, a diol compound having a rosin skeleton is produced by subjecting rosin and a trihydric alcohol to an esterification reaction, and this is used as a polyol component in a polyurethane synthesis reaction. (a) A diol compound, which is an esterification reaction product of rosin and trihydric alcohol, can be produced by, for example, esterifying 1 mole of rosin and 1 mole of trihydric alcohol by subjecting them to a heating reaction. , this reaction product has a rosin skeleton 1
It is a diol compound having two. Theoretically, this esterification reaction should be carried out until the acid value reaches 0, but in practice this is not necessarily necessary in the present invention, and if the reaction reaches an acid value of about 20 or less, a special problem will occur. There isn't. As the rosin used here, natural rosin such as gum rosin, udon rosin, tall oil rosin, processed rosin such as disproportionated rosin, hydrogenated rosin, or a mixture thereof can be used. As the trihydric alcohol, trimethylolpropane, trimethylolethane, glycerin, etc. can be used. A diol compound which is an esterified product with rosin can be obtained using a tetrahydric alcohol, for example, pentaerythritol, and this can be further used to produce a polyurethane resin having a side chain rosin skeleton similar to the polyurethane resin of the present invention. However, aqueous compositions containing such polyurethane resins have problems in practical use because the films obtained from them become extremely brittle, the stability of the composition is insufficient, or the composition dries too quickly. I don't like it because it can happen. However, the diol compound using a tetrahydric alcohol can be used in combination with a diol compound using a trihydric alcohol. On the other hand, when using glycerin, the reaction tends to be non-uniform and it is not necessarily a suitable polyhydric alcohol, but when used in combination with other polyhydric alcohols, the esterification reaction becomes easy and it can be used suitably. A particularly preferred polyhydric alcohol is trimethylolpropane. When producing the polyurethane resin of the present invention, this diol compound having a rosin skeleton must be used in an amount of 50 to 80% by weight of the total polyol compound components. If it is less than 50% by weight, the drying properties of the aqueous composition containing it and the adhesion to hydrophobic substrates will be insufficient, and if it is more than 80% by weight, the water dispersibility of the polyurethane resin will be insufficient. (b) Examples of aliphatic diol compounds containing a basic tertiary nitrogen atom include N-methyldiethanolamine, N-butyldiethanolamine, N-
Examples include methyldipropanolamine, 1,2-propanediol-3-dimethylamine, and the like. In particular, it is preferable to use methyldiethanolamine, which is commercially available at low cost. The amount used should be 20 to 50% by weight of the total polyol compound component. usage amount
If it is 20% by weight or more, the water dispersibility of the polyurethane resin will be poor, and if it is 50% by weight or more, water resistance and adhesiveness will be reduced. In addition to (a) and (b), other polyol compounds (c)
can be used in amounts up to 30% by weight of the total polyol component. As other polyol components that can be used, any of those used in general polyurethane synthesis can be used, and typical examples thereof include polyether polyols and polyester polyols. These (a) and (b) or (a), (b) and (c) components are reacted with an organic polyisocyanate compound to produce the water-dispersible polyurethane resin of the present invention. As the organic polyisocyanate compound used in the production of the polyurethane resin, any of the usual aliphatic or aromatic polyisocyanate compounds used in general polyurethane synthesis can be used. Specifically, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI)
Alternatively, mixtures thereof, and polyisocyanate prepolymers containing terminal isocyanate groups obtained from these diisocyanates can be used. This reaction may be carried out according to a conventional polyurethane synthesis reaction. For example, organic polyisocyanate compounds (a), (b) and
It is desirable to react with component (c) simultaneously or sequentially in multiple steps. This reaction can usually be carried out at a temperature of 30 to 100°C, and a urethanization reaction catalyst can optionally be used at this time. To the thus obtained organic solvent solution of the polyurethane resin having a side chain rosin skeleton and a basic tertiary nitrogen atom, an aqueous medium containing an acidic substance in an amount approximately equivalent to the basic tertiary nitrogen atom is added, and the aqueous medium is uniformly mixed. After dispersion, the organic solvent is distilled off to obtain an aqueous composition that is an aqueous dispersion of the polyurethane resin of the present invention. Furthermore, the water-dispersible polyurethane resin of the present invention is
Due to its high surface activity, general hydrophobic resins,
It is particularly effective as a dispersant for rosin resins and the like. The use of this performance is, for example, in that a uniform and stable aqueous dispersion of a rosin resin can be obtained by coexisting a rosin resin or the like when dispersing the polyurethane resin in water. On the other hand, the aqueous composition of the present invention has good wettability to the surface of a hydrophobic substrate and dries quickly, so that the dried film can adhere well to the hydrophobic surface. Such excellent effects of the present invention are attributable to the unique structure of the water-dispersible polyurethane resin that constitutes the main component of the aqueous composition of the present invention, and in particular, its surface active ability and unmodified rosin. It is assumed that this is based on the characteristics of the skeleton. The aqueous composition of the present invention is excellent as a surface treatment agent for molded products such as coating agents, and can also be expected to be used in adhesives and the like. Furthermore, by mixing it with pigments and dyes, it can be expected to be used in paints, printing inks, etc. Hereinafter, the present invention will be specifically explained based on Examples. Example 1 (i) Preparation of ester diol compound of rosin and trimethylolpropane 500 ml equipped with stirrer, reflux condenser with water trap, thermometer and nitrogen gas inlet tube
Chinese gum rosin (WG) is placed in a four-necked flask.
188g) 74g of trimethylolpropane was charged, and the temperature was gradually raised to 255℃ while passing nitrogen gas. After that, it was kept at the same temperature for another 6 hours, and the rosin ester diol compound with an acid value of 10 was
Obtained 245g. (ii) Preparation of water-dispersible polyurethane resin and the aqueous dispersion solution 40 g of acetone was placed in a 500 ml four-necked flask, and 41.6 g of the ester diol compound obtained in the above (i) was added.
After preparing g and dissolving, diphthyltin dilaurate
0.06 g was added, and 32.6 g of tolylene diisocyanate (TDI) was added dropwise at room temperature. Thereafter, the temperature was raised and maintained at the reflux temperature of acetone, and the reaction was continued at the same temperature for 1 hour. The system was then cooled to room temperature and treated with acetone.
13.4 g of methyldiethanolamine (MDEA) dissolved in 40 g was gradually added dropwise. After the heat generation has stopped, the temperature is raised to the reflux temperature of acetone.
The reaction was carried out for a period of time to obtain an acetone solution of water-dispersible polyurethane resin. The above acetone solution of the water-dispersible polyurethane resin was subjected to a distillation operation to remove a portion of the acetone.
Next, add 8 g of acetic acid and 154 g of water and stir thoroughly.
After dispersion, the remaining acetone is distilled off under reduced pressure at approximately 65℃ for 1 hour, and the non-volatile components are further diluted with water.
A 35% brown clear aqueous dispersion (PH4.4) was obtained. Application example A commercially available rosin resin (M-231 manufactured by Seiko Kagaku Kogyo Co., Ltd.; acid value 100, melting point 142°C ) was added and dissolved. Next, 8 g of acetic acid and 192 g of water were added, thoroughly stirred and dispersed, and then subjected to vacuum distillation to remove acetone. The resulting translucent aqueous dispersion has a non-volatile content of 35.2
%, PH4.3. Test Example Each of the aqueous dispersions obtained in Example 1 and Application Examples was applied to a modified polyethylene sheet and a surface-treated polypropylene sheet using a barcoder (No. 8), and the drying properties and transparency of the coating were evaluated. The results are shown in the table below. For comparison,
Similar tests were conducted on the aqueous solution (rosin-containing polyurethane; solvent water/isopropyl alcohol = 1/1) described in Example 1 of JP-A-54-143306, and the results are also shown in the table below as a comparative example. 【table】

Claims (1)

[Scope of Claims] 1. A polyurethane resin obtained by reacting an organic polyisocyanate compound and a polyol compound at an equivalent ratio of NCO:OH=1:0.8 to 1.5,
The above polyol compound is (a) 50 to 80% by weight of a diol compound that is an esterification product of rosin and a trihydric alcohol (b) 20 to 50% by weight of an aliphatic diol compound containing a basic tertiary nitrogen atom (c) An aqueous composition consisting of a polyurethane resin [A] containing 0 to 30% by weight of other polyol compounds, an acidic substance [B], and an aqueous medium [C], and the content of [A] is determined by the weight of the composition. 1 to 50 for
% by weight, the content of [B] is 0.8 to 1.5 equivalents per equivalent of basic tertiary nitrogen atom in [A], and the remainder is [C].