JP5205753B2 - NOVOLAC TYPE PHENOL RESIN AQUEOUS DISPERSION AND PROCESS FOR PRODUCING THE SAME - Google Patents

Description

  The present invention relates to an aqueous dispersion of a novolac type phenol resin and a method for producing the same. Specifically, the present invention relates to an aqueous novolak-type phenol resin dispersion useful for paints, adhesives, binders, resin processing agents, and the like, and a method for producing the same.

Phenol resin is a thermosetting resin because its cured product exhibits excellent heat resistance, mechanical properties, and chemical resistance, and is used as an electrical component, electronic component, automobile-related component, or paper, fiber, nonwoven fabric, and woody material. It is widely used in the fields of binders such as glass fiber, sand and other inorganic materials, paints, resin processing agents, adhesives and surface treatment agents.
Among the various uses described above, in the fields of binders such as inorganic materials, paints, resin processing agents, adhesives, surface treatment agents, etc., phenolic resins are usually water-insoluble, so they are usually used as organic solvent solutions. It has been.

  In recent years, there has been a strong demand for aqueous phenol resins from the viewpoint of reducing environmental burdens or mixing with aqueous resins, and the development of aqueous phenol resin solutions or aqueous phenol resin dispersions is desired.

  From the viewpoint of making the thermosetting resin water-soluble, for example, a resol-type phenol resin can be made water-based relatively easily by adjusting the molecular weight and the number of functional groups because of its inherent properties. On the other hand, since the phenol resin is usually a solid resin at room temperature, it is difficult to make it water-based, and even if the aqueous dispersion is adjusted, the average particle size of the dispersed resin particles is 10 μm to Since it is in a very large range of 100 μm, long-term dispersion stability cannot be obtained, leading to the sedimentation of resin particles.

  Thus, as a method for favorably dispersing the phenol resin in water, for example, a method of forming a phenol resin emulsion using a high molecular weight dispersant is known (see Patent Document 1 below). However, according to such a method, although the storage stability is certainly improved, a polymer dispersant having a mass approximately half that of the novolak resin is required, and the original characteristics of the novolak resin are lost. It was.

  On the other hand, a technique is known in which a phenolic resin is dispersed in water in a molten state to form an emulsion, and then a protective colloid is added to reduce the size and stabilize the dispersed particles (see Patent Document 2 below). However, even with a phenol resin dispersion produced by such a method, the dispersed particle diameter is in a range exceeding 1 μm as described in the Examples of Patent Document 2. The high storage stability required in recent years has not been achieved.

JP-A-7-97504 US Pat. No. 5,670,571

  Therefore, the problem to be solved by the present invention is that the resin particles dispersed in the aqueous medium can be reduced in size without using a large amount of dispersant, and storage stability can be dramatically improved. An object of the present invention is to provide an aqueous novolak-type phenolic resin dispersion and a method for producing the same.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have 3 to 30 carbon atoms as a substituent on the aromatic nucleus in the molecular structure of the novolac type phenol resin dispersed in the aqueous medium. By introducing an acid group-containing aliphatic hydrocarbon group and adjusting the pH in the aqueous medium to a range of 7.0 to 9.0, the novolac type can be used without using a large amount of dispersant. The resin particle diameter of the phenol resin can be reduced to less than 1 μm, and the aqueous dispersion has been found to exhibit excellent storage stability, and the present invention has been completed.

That is, the present invention is a novolak-type phenol resin aqueous dispersion in which rapeseed oil-modified novolak-type phenol resin particles are dispersed in an aqueous medium, wherein the aqueous medium contains casein and hydroxyalkyl cellulose. The present invention relates to an aqueous novolak-type phenol resin dispersion.

The present invention further relates to a method for producing an aqueous dispersion of novolak-type phenolic resin, which comprises adding a rapeseed oil-modified novolak-type phenolic resin, casein, hydroxyalkylcellulose, and an aqueous medium to form an aqueous dispersion.

  According to the present invention, in a novolac type phenol resin aqueous dispersion in which a novolak type phenol resin is dispersed in an aqueous medium, the resin particles dispersed in the aqueous medium are reduced in size without using a large amount of dispersant. And storage stability can be dramatically improved.

  The novolac-type phenol resin used in the present invention has a structure obtained by reacting phenols and aldehydes in the presence of a catalyst as a main chemical structure, and has a carbon atom as a substituent on the aromatic nucleus in the molecule. It has the acid group containing aliphatic hydrocarbon of several 3-30. The present invention can drastically improve the dispersibility of the novolak resin in an aqueous medium by introducing a chained aliphatic hydrocarbon group containing an acid group into the novolak resin structure. Thus, an aqueous dispersion that has a small particle diameter and is stable over a long period of time can be obtained. Examples of the acid group-containing aliphatic hydrocarbon group having 3 to 30 carbon atoms include linear or branched alkyl groups or alkenyl groups having an acid group such as a carboxyl group, a sulfonic acid group, and a thiol group. . Specifically, the method of introducing an acid group-containing aliphatic hydrocarbon group into a novolak-type phenol resin includes a novolak-type phenol resin and an unsaturated fatty acid having 3 to 30 carbon atoms (hereinafter simply referred to as “unsaturated fatty acid”). Or a novolac type phenol obtained by reacting a raw material phenol of the novolac type phenol resin with an unsaturated fatty acid and then reacting it with an aldehyde. The method of manufacturing resin is mentioned. Therefore, the acid group-containing aliphatic hydrocarbon group is preferably an acid group-containing aliphatic hydrocarbon group derived from the unsaturated fatty acid, specifically, a carboxylpropyl group, a carboxylundecyl group, a carboxy group. A tridecyl group, a carboxyheptadecyl group, etc. are mentioned.

  Specific examples of unsaturated fatty acids used for the introduction of acid group-containing aliphatic hydrocarbon groups include crotonic acid, lauric acid, myristoleic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, Examples thereof include compounds such as eleostearic acid and behenic acid, and other natural unsaturated fatty acids such as rapeseed oil, tung oil, soybean oil and cashew oil.

  The phenols used as the raw material for the novolak type phenol resin are, for example, phenol; alkylphenols such as cresol, xylenol, ethylphenol, butylphenol, octylphenol; polyhydric phenols such as resorcin, catechol, bisphenol A; halogenated phenol. , Phenylphenol, aminophenol and the like. Of these, phenol and cresol are particularly preferred from the viewpoint of excellent dispersibility.

  Examples of the aldehydes include formaldehyde such as formaldehyde, paraformaldehyde, and trioxane, and acetaldehyde. Two or more of these aldehydes may be used in combination. Moreover, you may use as 37-95 mass% formaldehyde.

A novolak type phenol resin having an acid group-containing aliphatic hydrocarbon group having 3 to 30 carbon atoms as a substituent on the aromatic nucleus (hereinafter, abbreviated as “acid group-containing novolak resin”). In order to manufacture), specifically,
(1) A method of reacting phenols and aldehydes in the presence of a catalyst to obtain a novolak type phenol resin, and then reacting this with an unsaturated fatty acid (2) Reacting phenols and an unsaturated fatty acid in the presence of a catalyst To obtain an acid group-containing aliphatic hydrocarbon group-containing phenol having 3 to 30 carbon atoms, and reacting this with an aldehyde in the presence of a catalyst to obtain a desired novolak-type phenol resin,
(3) Phenols and unsaturated fatty acids are reacted in the presence of a catalyst to obtain an acid group-containing aliphatic hydrocarbon group-containing phenol having 3 to 30 carbon atoms, which is catalyzed with phenols and aldehydes. A method of reacting in the presence,
Is mentioned. Among these, phenols and unsaturated fatty acids are reacted in the presence of a catalyst to obtain phenols containing an acid group-containing aliphatic hydrocarbon group having 3 to 30 carbon atoms, particularly from the viewpoint of excellent productivity. A method in which an aldehyde is reacted in the presence of a catalyst to obtain a target novolak type phenol resin is preferable.

  In the above methods (1) to (3), examples of the catalyst used for the reaction between phenols and unsaturated fatty acids and the reaction between phenols and aldehydes include oxalic acid, sulfuric acid, and paratoluenesulfonic acid. Can be mentioned. Two or more of these catalysts may be used in combination. Further, the amount of the catalyst added is not particularly limited, but is preferably 0.05 to 5 parts by mass with respect to 100 parts by mass of phenols, and may be in the range of 0.1 to 3.0 parts by mass. Particularly preferred.

  The acid group-containing novolac resin described above preferably has a difficulty point of 70 to 120 ° C. from the viewpoint of excellent dispersibility. Further, the content of the acid group-containing aliphatic hydrocarbon group having 3 to 30 carbon atoms in the acid group-containing novolak resin is such that the unsaturated fatty acid is 2 to 50 parts by mass with respect to 100 parts by mass of the phenols based on the raw material. A ratio in the range is preferable from the viewpoint of dispersibility in an aqueous medium, and a ratio in the range of 5 to 20 parts by mass is particularly preferable.

  The method for producing the aqueous novolak-type phenolic resin dispersion of the present invention using the acid group-containing novolak resin described in detail above is a method of converting an acid group-containing aliphatic hydrocarbon group having 3 to 30 carbon atoms into a substituent on an aromatic nucleus. And a novolac type phenolic resin, casein, hydroxyalkyl cellulose, and a method of adding an aqueous medium.

  Here, casein and hydroxyalkyl cellulose are used as a dispersant, and may be used in the form of a powder or may be used as an aqueous solution. In the present invention, by using casein and hydroxyalkyl cellulose in combination as a dispersant as described above, the diameter of the dispersed resin particles can be reduced, and the storage stability of the aqueous dispersion can be dramatically improved. it can.

  Examples of the hydroxyalkyl cellulose used here include hydroxyethyl cellulose and hydroxypropyl cellulose. Among these, hydroxyethyl cellulose is particularly preferable because the dispersion stability of the novolak type phenol resin is remarkably excellent.

  In addition, water can be used as the aqueous medium, but the aqueous medium may contain a water-soluble organic solvent such as methanol, ethanol, and acetone in the range of 0.1 to 5% by mass or less. In the present invention, as will be described later, an organic solvent may be used in the production of the aqueous novolak-type phenol resin dispersion, which is eventually distilled off, but cannot be completely removed. It may remain in it and become compatible with water. In the present invention, such a mixed solution is also included in the aqueous medium.

  Specific examples of the production method include the following methods 1 to 3.

Method 1: A method in which an acid group-containing novolak resin is heated and melted, and an aqueous solution of casein and an aqueous solution of hydroxyalkyl cellulose are mixed to obtain an aqueous dispersion.
Method 2: An acid group-containing novolak resin is dissolved in an organic solvent, and then an aqueous solution of casein and an aqueous solution of hydroxyalkyl cellulose are mixed to form an aqueous dispersion, and then part or all of the organic solvent is distilled off. Method.
Method 3: A method in which an acid group-containing novolak resin is melted or dissolved in an organic solvent and mixed with casein and hydroxyalkyl cellulose to obtain a mixture, and then an aqueous medium is added to the mixture to obtain an aqueous dispersion. .

  Among the above methods 1 to 3, method 3 is particularly preferable because it is excellent in reducing the diameter of the acid group-containing novolak resin particles and the storage stability becomes remarkable.

The method 3 will be described in more detail.
Method 3a: An acid group-containing novolak resin is heated and melted, and powdered casein and powdered hydroxyalkyl cellulose are mixed to obtain a mixture, and then an aqueous medium is added to the mixture to form an aqueous dispersion. how to,
Method 3b: A method in which an acid group-containing novolak resin is heated and melted, and then an aqueous solution of casein and an aqueous solution of hydroxyalkyl cellulose are mixed, and an aqueous medium is further added to form an aqueous dispersion.
Method 3c: An acid group-containing novolak resin is dissolved in an organic solvent and mixed with casein and hydroxyalkyl cellulose to obtain a mixture. Then, an aqueous medium is added to the mixture to form an aqueous dispersion. A method of distilling off part or all of the solvent can be mentioned.

  Among these, the method 3c is particularly preferable from the viewpoint of reducing the particle size of the dispersed particles and being excellent in productivity. In the method 3c, the casein and hydroxyalkyl cellulose may be in the form of powder or an aqueous solution, but in the present invention, the latter aqueous solution is used as a dispersant for casein and hydroxyalkyl cellulose. This is preferable from the viewpoint of good dispersibility.

  In the method 3, when an aqueous solution of casein and an aqueous solution of hydroxyalkyl cellulose are used, the concentration is preferably in the range of 5 to 20% by mass from the viewpoint of enhancing the performance as a dispersant.

  In each production method described above, when casein and hydroxyalkyl cellulose are used as an aqueous solution, the aqueous casein solution is first added to the novolac type phenol resin in a molten state or the novolac type phenol resin in an organic solvent solution state. Next, the hydroxyalkyl cellulose aqueous solution is added, the former functions as a surfactant, and the latter functions as a protective colloid, which reduces the diameter of the dispersed resin particles and the storage stability of the aqueous novolak phenol resin dispersion. It is preferable from the point.

  In addition, the amount of casein used in each of the above production methods is a ratio of 3.0 to 10.0 parts by mass with respect to 100 parts by mass of the acid group-containing novolac resin solid content. Dispersion stability of the acid group-containing novolac resin From the point of view, it is preferable.

  On the other hand, the amount of hydroxyalkyl cellulose used is preferably in the range of 0.3 to 3 parts by mass with respect to 100 parts by mass of the solid content of acid group-containing novolak resin, from the viewpoint of dispersion stability of the acid group-containing novolak resin. . In the present invention, by using casein and hydroxyalkyl cellulose in combination as described above, excellent dispersion stability can be achieved without using any high molecular weight dispersing agent, and the amount used is extremely small. The point that can be made is a special point.

  Further, in the present invention, the pH of the aqueous medium in the finally obtained novolak type phenol resin aqueous dispersion is in the range of 7.0 to 9.0, the dispersed particle diameter becomes smaller, and It is preferable from the viewpoint that the viscosity of the aqueous dispersion is reduced, and particularly preferably in the range of 7.3 to 8.0 from the viewpoint that these effects become remarkable.

  In order to adjust the pH in the aqueous medium in the aqueous dispersion, it is desirable to add a basic substance to the acid group-containing novolak resin or the aqueous dispersion at any stage of the above-described methods. In the case of Method 3, it is preferable to add the aqueous medium before adding it, in particular, together with casein and hydroxyalkyl cellulose, from the viewpoint of reducing the diameter of the dispersed particles and reducing the viscosity of the dispersion.

  Examples of the basic substance used here include sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, sodium carbonate, ammonia, triethylamine, dimethylethanolamine, triethanolamine, hexamethylenetetramine and the like. You may use individually and 2 or more types together.

  In each of the above production methods, organic solvents that can be used when the acid group-containing novolak resin is dissolved with an organic solvent are alcohols such as methanol, ethanol, propanol, and butanol, and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone. And esters such as ethyl acetate and butyl acetate.

  In addition, the organic solvent solution preferably has a solid concentration in the range of 40 to 70% by mass from the viewpoint of excellent water dispersibility.

  The aqueous novolak-type phenol resin dispersion thus obtained has a particle size of less than 1 μm, and specifically, the average particle size is in the range of 0.01 to 0.6 μm. Instead, there is no formation of sediment, and it is preferable from the viewpoint of forming an aqueous dispersion excellent in storage stability while maintaining a low viscosity.

  The novolak-type phenolic resin aqueous dispersion of the present invention described in detail above can be cured by adding a curing agent such as hexamethylenetetramine, epoxy resin, isocyanate or the like depending on the application.

  The novolac type phenolic resin aqueous dispersion of the present invention exhibits excellent storage stability without using a large amount of a dispersant, and thus can be applied to various uses. Paper, fiber, non-woven fabric, woody material Applications such as binders such as glass fiber, sand and other inorganic materials, paints, resin processing agents, adhesives, and surface treatment agents are particularly suitable.

  The present invention will be specifically described below with reference to examples. In addition, all the parts and% in an example represent a mass part and the mass%.

Example 1
1300 g of phenol and 1300 g of rapeseed oil were added to a four-necked 3 liter flask equipped with a stirrer, a condenser and a thermometer, and stirring was started. As a catalyst, 6.5 g of 98% sulfuric acid was added and reacted at 120 ° C. for 3 hours to obtain a rapeseed oil-modified phenol (A1).
542.4 g of rapeseed oil-modified phenol (A1), 1536 g of phenol, and 1029.5 g of 42% by weight formaldehyde aqueous solution were added to a four-necked 3 liter flask equipped with a stirrer, condenser and thermometer, heated to 100 ° C. and allowed to react for 1 hour. It was. The temperature was lowered to 90 ° C., 5.4 g of oxalic acid was added, the temperature was raised to 100 ° C., and the reaction was allowed to proceed for 5 hours. Then, distillation was started and the temperature was raised to 170 ° C. while removing water. After partially removing free phenol by reducing the pressure at 170 ° C., it was taken out from the reaction vessel to obtain an acid group-containing novolak resin (A2).
To a four-necked 3 liter flask equipped with a stirrer, condenser, thermometer and dropping funnel, 1000 g of (A2) and 800 ml of ethanol were added and dissolved at 65 ° C., 44 g of 25% sodium hydroxide, 500 g of 10% casein aqueous solution, 5% 200 g of an aqueous hydroxylethylcellulose solution was added and allowed to react for 3 hours, and 1000 g of ion-exchanged water was gradually added from the dropping funnel, and further reacted for 1 hour. Thereafter, ethanol was distilled off under reduced pressure to obtain a novolak-type phenol resin aqueous dispersion (B1). The nonvolatile content of B1 was 39.0%, the pH was 7.95, the average particle size was 0.4 μm, and the storage stability was good for 6 months at room temperature.

Example 2
To a four-necked 3 liter flask equipped with a stirrer, a condenser and a thermometer, 233 g of rapeseed oil-modified phenol (A1), 1819 g of phenol, and 1102 g of 42% formaldehyde aqueous solution were added, heated to 100 ° C. and reacted for 1 hour. The temperature was lowered to 90 ° C., 9 g of oxalic acid was added, the temperature was raised to 100 ° C., and the reaction was allowed to proceed for 5 hours. Then, distillation was started and the temperature was raised to 170 ° C. while removing water. After partially removing free phenol at 170 ° C. under reduced pressure, it was taken out from the reaction vessel to obtain an acid group-containing novolak resin (A3).
To a four-necked 3 liter flask equipped with a stirrer, condenser, thermometer and dropping funnel, 1000 g of (A3) and 800 ml of ethanol were added and dissolved at 65 ° C., 18 g of 25% sodium hydroxide, 600 g of 10% casein aqueous solution, 5% 200 g of an aqueous hydroxylethylcellulose solution was added and allowed to react for 3 hours, and 1000 g of ion-exchanged water was gradually added from the dropping funnel, and further reacted for 1 hour. Thereafter, ethanol was distilled off under reduced pressure to obtain a novolak-type phenol resin aqueous dispersion (B2). The aqueous novolak phenol resin dispersion (B2) had a nonvolatile content of 41.2%, a pH of 8.01, an average particle size of 0.5 μm, and good storage stability for 6 months at room temperature.

Example 3
In a four-necked 3 liter flask equipped with a stirrer, a condenser and a thermometer, 116.6 g of rapeseed oil-modified phenol (A1), 1887 g of phenol, 1108 g of 42% aqueous formaldehyde solution, heated to 100 ° C. and reacted for 1 hour. The temperature was lowered to 90 ° C., 9 g of oxalic acid was added, the temperature was raised to 100 ° C., and the reaction was allowed to proceed for 5 hours. After partially removing free phenol at 170 ° C. under reduced pressure, it was taken out from the reaction vessel to obtain an acid group-containing novolak resin (A4).
To a four-necked 3 liter flask equipped with a stirrer, condenser, thermometer and dropping funnel, 1000 g of (A4) and 800 ml of ethanol were added, dissolved at 65 ° C., 10 g of 25% sodium hydroxide, 600 g of 10% casein aqueous solution, 5% 200 g of an aqueous hydroxylethylcellulose solution was added and allowed to react for 3 hours, and 1000 g of ion-exchanged water was gradually added from the dropping funnel, and further reacted for 1 hour. Thereafter, ethanol was distilled off under reduced pressure to obtain a novolak-type phenol resin aqueous dispersion (B3). The aqueous novolak phenol resin dispersion (B3) had a non-volatile content of 39.4%, a pH of 8.23, an average particle size of 0.5 μm, and good storage stability for 6 months at room temperature.

Comparative Example 1
To a 4-neck 3 liter flask equipped with a stirrer, condenser, thermometer and dropping funnel, add 1000 g of (A2) and 800 ml of ethanol, dissolve at 65 ° C., add 44 g of 25% sodium hydroxide and 600 g of 10% casein aqueous solution, The reaction was performed for 3 hours, and 1000 g of ion exchange water was gradually added from the dropping funnel, and the reaction was further continued for 1 hour. Thereafter, ethanol was distilled off under reduced pressure to obtain a novolak-type phenol resin aqueous dispersion (B4). The aqueous novolak phenol resin dispersion (B4) had a non-volatile content of 40.5%, a pH of 8.14, an average particle size of 1.8 μm, and no separation or sedimentation was observed up to 7 days at room temperature. Thereafter, the resin gradually separated and the storage stability was poor.

Claims (8)

An aqueous novolac type phenol resin dispersion in which rapeseed oil-modified novolac type phenol resin particles are dispersed in an aqueous medium, wherein the aqueous medium contains casein and hydroxyalkyl cellulose, and the aqueous novolac type phenol resin Dispersion.   The novolac type phenol resin aqueous dispersion according to claim 1, wherein the pH in the aqueous medium is in the range of 7.0 to 9.0.   The aqueous novolak-type phenol resin dispersion according to claim 1, wherein the phenol novolac resin particles dispersed in the aqueous medium have an average particle diameter of 0.01 to 0.6 µm. The casein is contained in an aqueous medium at a ratio of 3.0 to 10.0 parts by mass with respect to 100 parts by mass of the rapeseed oil-modified novolac type phenol resin, and 0.3% with respect to 100 parts by mass of the novolac type phenol resin. phenolic novolak resin aqueous dispersion according to claim 1, wherein a ratio of the 3.0 parts by weight containing the hydrate carboxyalkyl cellulose in an aqueous medium. A method for producing an aqueous novolak type phenol resin dispersion comprising adding a rapeseed oil-modified novolac type phenol resin, casein, hydroxyalkyl cellulose, and an aqueous medium to form an aqueous dispersion. A rapeseed oil-modified novolak type phenolic resin is dissolved in an organic solvent, mixed with casein and hydroxyalkyl cellulose to obtain a mixture, an aqueous medium is added to the mixture to form an aqueous dispersion, and then the aqueous dispersion is mixed with the organic solvent. The production method according to claim 5, wherein a part or all of the solvent is distilled off. The production method according to claim 5 or 6 , wherein a basic substance is added to the novolac type phenol resin or an aqueous dispersion thereof to adjust the pH in the aqueous medium to a range of 7.0 to 9.0. The method for producing an aqueous novolak-type phenol resin dispersion according to claim 5 , 6 or 7 , wherein the rapeseed oil-modified novolak-type phenol resin is obtained by reacting a reaction product of phenols and rapeseed oil with an aldehyde compound. .