JPS58219252A - Aqueous emulsion of thermosetting resin - Google Patents

Abstract

PURPOSE:To prepare an aqueous emulsion having excellent dispersibility and stability, and applicable to a molded article without deteriorating its water resistance and electrical properties, by dispersing a phenolic resin obtained by the use of a basic nitrogen compound as a catalyst, in water in the presence of a specific polyvinyl alcohol. CONSTITUTION:A phenolic resin obtained by the reaction of a phenolic compound with a formaldehyde compound in the presence of a basic nitrogen compound is dispersed in water using a polyvinyl alcohol having hydrophobic group and hydrophylic group in its structure and having a saponification degree of 80- 100% and a polymerization degree of 500-2,800. The hydrophobic group of the polyvinyl alcohol is e.g. -OCOR, -OR (R is >=6C aliphatic hydrocarbon group), etc., and its number is 0.001-0.2 per one polymerization unit. The hydrophilic group is, e.g. -COOH, etc., and its number is preferably 0.001-0.2 per one polymerization unit. The amount of the polyvinyl alcohol is preferably 1-5wt% based on the solid content of the resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resol type phenolic resin aqueous emulsion having excellent stability.

The purpose of this is to improve the shortcomings associated with the use of conventionally known organic solvent-soluble phenolic resins, such as the danger of ignition, poisoning, odor, and other health issues for the human body, workability, and economic efficiency. An object of the present invention is to provide a phenolic resin aqueous emulsion with a high temperature.

Conventionally, phenolic resins have excellent heat resistance, mechanical properties, electrical insulation properties, etc., and are used in laminated materials, adhesives, paints, molding materials, etc.

When using phenolic resins for these purposes, they are dissolved in organic solvents such as alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, and aromatic hydrocarbons such as benzene and toluene. There is a strong demand for the development of phenolic resins that do not use organic solvents, since they pose hygienic problems to the human body such as flammability, odor, and poisoning, and are economically expensive.

On the other hand, several phenolic resin aqueous emulsions using conventional polyvinyl alcohol have been reported;
When the emulsion is applied to molded products, etc., properties such as water resistance and electrical performance are lower than those of conventional organic solvent-soluble resins due to the influence of polyvinyl alcohol. This is because polyvinyl alcohol does not have an adverse effect, but if the amount added is reduced until this effect disappears, there is a problem that the stability of the emulsion deteriorates.

The present inventors have repeatedly studied the properties of phenolic resins, particularly hydrophilicity and hydrophobicity, and based on the knowledge obtained from them, have conducted extensive research into emulsifiers suitable for phenolic resol resins. By using polyvinyl alcohol which has sexual functional groups in its structure, it has excellent dispersibility and stability, and when applied to molded products, it is a phenolic resin aqueous emulsion that does not impair properties such as water resistance and electrical performance. They discovered that a liquid can be obtained and completed the present invention.

That is, the present invention uses phenols and formaldehydes,
When reacting in the presence of a basic nitrogen compound as a catalyst and dispersing the produced phenolic resin in water, it has a hydrophobic functional group and a hydrophilic functional group as an emulsifier in its structure and has a saponification degree of 80 or more. The present invention relates to an aqueous emulsion of a phenolic resin using polyvinyl alcohol having a polymerization degree of 500 or more and 2,800 or less.

The present invention will be explained in more detail below.

As the phenols used in the present invention, phenols such as phenol, orthocresol, metacresol, para-cresol, xylenol, para-phenylphenol, para-tertiary-butylphenol, para-tertiary-amylphenol, bisphenol, and resorcinol are preferably used.

Further, formaldehydes used in the reaction with phenols include formaldehyde, paraformaldehyde, hexamethylenetetramine, and furfural.

Basic nitrogen compounds used as reaction catalysts include ammonia, methylamine, dimethylamine, trimethylamine,
Ethylamine, diethylamine, triethylamine, n
-Propylamine, isopropylamine, hexamethylenetetramine, benzylamine, triethanolamine, pyridine, etc.

Generally, alkali metal hydroxides, salts, and basic nitrogen compounds are used as catalysts for reactions to obtain phenolic resol resins. When compared with the resins obtained by using alkali metal hydroxides, there is a remarkable difference in the stability of the emulsions; the basic nitrogen compounds have excellent stability of more than one month, while the alkali metal hydroxides have excellent stability of more than one month. In some cases, precipitation occurred within a few days. This is thought to be because the alkali metal ions of the alkali metal hydroxide remaining in the resin adversely affect the stability of the emulsion.

The resin suitable for the emulsion used in the present invention may be subjected to a usual phenol-formahide reaction, but in this case it is necessary to use a basic nitrogen compound such as ammonia or amines as a reaction catalyst.

Phenolic resins compatible with the present invention also include those modified with modifiers. As a denaturing agent, anisono,
Includes melamine, dianediamide, guanidine, benzoguanamine, acetoguanamine, urea, thiourea, ethylene urea, benzene sulfonamide, polyamide, alkylbenzene formaldehyde resin, xylene resin, silicone resin, tung oil, hemp seed oil, and the like. In order to obtain a modified phenolic resin, phenols, aldehydes, and a modifier can be simultaneously charged and reacted, or the modifier can be added after the phenols and formaldehydes have reacted (if necessary, the aldehyde can be added). (adding aldehydes as necessary), or reacting the modifier and aldehydes, then adding phenols (adding aldehydes if necessary), or reacting the phenols with aldehydes and the modifier. After separately reacting with aldehydes,
A method is used in which they are mixed or reacted after mixing (adding aldehydes as necessary), and normal temperature, pH control, etc. are carried out in all reactions.

The polyvinyl alcohol used in the present invention has a saponification degree of 80 to 100 degrees and a polymerization degree of 500 to 26 degrees.
00 or less, and has a hydrophobic functional group and a hydrophilic functional group in its structure.

The hydrophobic functional groups mentioned here are “-0COR,”
-OR, -R3, where R and -R3 are aliphatic hydrocarbons having 6 or more carbon atoms. The hydrophilic functional group is represented by -COOHl-R4COOH, where R4 is an aliphatic hydrocarbon having 1 to 5 carbon atoms.

The preferred content of hydrophobic functional groups in the polyalcohol used in the present invention is -0COR1, -OR,, -R
, the content of hydrophilic functional groups is 0.001 (11 to 0.2) per polymerized unit of polyvinyl alcohol, and the content of hydrophilic functional groups is
The number of one or two types of 4COOH is 0.001 or more and 0.2 or more per polymerized unit of polyvinyl alcohol.

The important point in the present invention is that polyvinyl alcohol, which is a general polyvinyl alcohol containing a hydrophobic functional group and a hydrophilic functional group in its structure, is used as an emulsifier. In addition to its properties as a protective colloid, it also has a strong surface-active effect due to its hydrophobic and hydrophilic functional groups.

In order to have a strong surfactant effect, it is necessary to have a limited number of hydrophobic functional groups and hydrophilic functional groups. [ii If it is less than 1, the hydrophobicity will be weakened and the surfactant effect will be reduced. Similarly, if the number of carbon atoms in R4 in -R4C00H, which is a hydrophilic functional group, is 6 or more, the hydrophilicity will be weakened and the surface-active effect will be weakened.

In addition, the content of functional groups in polyvinyl alcohol is 0.00 per polymerized unit of polyvinyl alcohol.
If the number is less than 1, the function as a hydrophobic functional group is virtually eliminated, and if it exceeds 0.2, the hydrophobicity of the emulsifier becomes too strong and the surface-active function is lost. On the other hand, if the hydrophilic functional group is less than O,'OO111N per polymerized unit of polyvinyl alcohol, it will not function as a hydrophilic functional group substantially;
If it exceeds 0.2 (liil), the hydrophilicity of the emulsifier becomes too strong and the surfactant effect disappears.

Further, if necessary, a surfactant can be used in combination with polyvinyl alcohol. As a surfactant,
Examples include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, boroxyethylene polyoxybrobylene ether, polyoxyethylene sorbitan alkyl ester, and the like.

The amount of polyvinyl alcohol added is 0.5 to 10% by weight, preferably 1 to 5% by weight based on the solid content of the phenolic resin. If the amount added is larger than this, the heat resistance, water resistance, mechanical properties, etc. of laminates, adhesives, paints, molding materials, etc. manufactured using the emulsion will be inferior to those using organic solvent-soluble resins. If the amount added is smaller than this, the dispersibility and stability of the emulsion will deteriorate.

The method for producing the aqueous emulsion of phenolic resol resin in the present invention is similar to the method for producing a general emulsion, and polyvinyl alcohol is added before, during, or after the reaction of the phenolic resin. By adding water while stirring and mixing, an aqueous emulsion containing a resin solid content suitable for use can be obtained.

The aqueous phenolic resol resin emulsion obtained by the present invention has better water resistance, electrical properties, etc. of products manufactured using it, such as molded products, than those of conventional emulsions using polyvinyl alcohol. It has excellent emulsion dispersibility and stability, compared to conventional resin solutions using organic solvents.
Due to dangers such as flash points, odors, and health concerns for the human body such as poisoning,
It also improves workability, economy, and other problems. In addition, various fillers are used for applications such as molding materials, laminated materials, adhesives, paints, binding materials, electrical insulation materials, friction materials, abrasive materials, casting materials, impregnation materials for valves, printing inks, castings, grindstones, etc. Good characteristics can be obtained in combination with

The present invention will be further explained in detail with reference to Examples below.

Example 1 Phenol 1000.9 and 37 thiformalin 990 g were reacted in the presence of 25 thiammonia water 30.9, and the resulting resin 100011 had a saponification degree of 85%, a polymerization degree of 2000, and a hydrophobic -0C0CI as a sexual functional group
300 g of a 10% by weight aqueous solution of polyvinyl alcohol having 0.011 IH23 substituents per polymerized unit of polyvinyl alcohol and 0.1 substituent -COOH as a hydrophilic functional group per polymerized unit of polyvinyl alcohol. The mixture was stirred and mixed at 40°C for 10 minutes. Thereafter, room temperature water was immediately added with stirring to obtain an emulsion with a resin solid content of 40% by weight.

This emulsion has excellent dispersibility and maintains stability for one month or more.

Further, this emulsion was applied to a molding material under the following formulation and conditions, and the performance of the molded product obtained is shown in Table 1.

(a) Prescription Emulsion 1000 parts by weight α-cellulose 120 parts by weight Zinc stearate
3 parts by weight Hexamethylenetetramine 0.5 parts by weight (b) Mixing conditions: Kneaded at 60°C for 5 minutes using a Sigma vane kneader.

(c) Drying conditions Dry with hot air drying method at 110℃ for 15 minutes.

Molding pressure 300KP/CP! Molding temperature: 160°C Molding time: 4 minutes Example 2 10QOg of meta and valacresol and 420g of 80% paraformaldehyde were reacted in the presence of 25% ammonia water 209, and the resulting resin 10001 had a saponification degree of 90. %, the degree of polymerization is 2000, the substituents -OCOC, Hss as hydrophobic functional groups are 0.0211i per polymerized unit of polyvinyl alcohol, the substituents -COOH and -CH, COO, H as hydrophilic functional groups. Each substituent is 0.00 per polymerized unit of polyvinyl alcohol.
500 g of a 10-fold IL-thi aqueous solution of polyvinyl alcohol having 04 molecules in its structure was added, and the mixture was stirred and mixed at 40°C for 10 minutes. Immediately thereafter, room temperature water was added while stirring to obtain an emulsion with a resin solid content of 40 cm by weight.

This emulsion has excellent dispersibility and maintains stability for one month or more.

Furthermore, this emulsion was applied to a molding material using the same formulation as in Example 1, and the performance of the molded product obtained is shown in Table 1.

Example 3 Phenol 10009 and 1100 g of 37% formalin were reacted in the presence of 45 g of triethanolamine. ! )(t
The substituents s and -QC, 8Hs are each on the 0.01 side per polymerized unit of polyvinyl alcohol, and the substituents -COOH and -CH,C are used as hydrophilic functional groups.
500 I of a 10-fold aqueous solution of polyvinyl alcohol having 005 0OH substituents per polymerized unit of polyvinyl alcohol was added, and 1
The mixture was stirred and mixed for 0 minutes. Immediately thereafter, room temperature water was added with stirring to obtain an emulsion with a resin solid content of 40 parts by weight.

This emulsion has excellent dispersibility and maintains stability for one month or more.

Further, this emulsion was applied to a molding material using the same formulation as in Example 1, and the performance of the molded product obtained is shown in Table 1.

Comparative example 1゜Example 1. Phenolic resin 100 similar to that used in
0.9, a saponification degree of 85%, a polymerization degree of 2000, but a 10% by weight aqueous solution of polyvinyl alcohol containing hydrophobic functional groups and hydrophilic functional groups in its structure.
1 was added, and the mixture was stirred and mixed at 40°C for 10 minutes.

Thereafter, room temperature water was immediately added with stirring to obtain an emulsion with a resin solid content of 40% by weight.

However, this emulsion had poor stability as a precipitate formed within one day. Further, the same method as in Example 1 was applied to a molding material, and the performance of the obtained molded product is shown in Table 1.

Comparative Example 2゜Phenol resin 1000 similar to that used in Example 1
1, the degree of saponification is 70, the degree of polymerization is 200, the substituent -OCOCo Hts is 0.01 per polymerized unit of polyvinyl alcohol as the hydrophobic functional group, and the substituent -COOH is the substituent -COOH as the hydrophilic functional group. After adding 1000 g of a 10% by weight aqueous solution of phosphorivinyl alcohol having 01 units per polymerized unit of polyvinyl alcohol in its structure and stirring and mixing at 40°C for 10 minutes, no emulsion was obtained.

As is clear from Table 1, according to the present invention, molded products with excellent water resistance and electrical performance, as well as good tensile strength and bending strength, could be obtained.

Claims (1)

[Claims] When dispersing in water the phenolic resin produced by reacting phenols and formaldehyde in the presence of a basic nitrogen compound, a saponification degree of 80%, which has hydrophobic functional groups and hydrophilic functional groups in its structure, is used. Above, 100%
Below, a phenolic resin aqueous emulsion using polyvinyl alcohol having a degree of polymerization of 500 or more and 2,800 or less.