JPS58219251A - 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, etc., by dispersing a specific phenolic resol resin obtained by the use of a basic nitrogen compound as a catalyst, in water. CONSTITUTION:A phenolic resol resin having a number-average molecular weight (Mn) of 300-650 and a weight-average molecular weight (Mw) of 1,500- 8,000, containing 0.30-0.50mol of methylol group (Qm) per 1mol of the benzene nucleus of the produced resin, and obtained by the reaction of a phenolic compound with a formaldehyde compound in the presence of a basic nitrogen compound, is dispersed in water in the presence of an emulsifier. The basic nitrogen compound is, e.g. ammonia, methylamine, pyridine, etc.

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, some aqueous emulsions of phenolic resins using polyvinyl alcohol have been reported, but when these emulsions are applied to molded products etc., due to the influence of polyvinyl alcohol, conventional organic solvent-soluble resins Properties such as water resistance and electrical performance deteriorate compared to This is because polyvinyl alcohol has 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 researched the properties of phenolic resins, particularly hydrophilicity and hydrophobicity, and based on the knowledge obtained from them, have discovered the structural characteristics of resins suitable for obtaining emulsions, and By dispersing the phenolic resin in water in the presence of an emulsifier, the phenolic resin has excellent dispersibility and stability, and also does not impair its properties such as water resistance and electrical performance when applied to molded products. It was discovered that an aqueous emulsion can be obtained, and the present invention was completed.

That is, in the present invention, phenols and formaldehydes are reacted in the presence of a basic nitrogen compound, and the structural characteristics of the resulting resin are number average molecular weight Mn = 300 to 650, weight average molecular weight ■r = 1500 to 8000, and raw resin. This invention relates to an aqueous phenolic resin emulsion in which a resin is dispersed in water in the presence of an emulsifier.

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.

Examples of the basic nitrogen compound as a reaction catalyst include ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, isopropylamine, hexamethylenetetramine, benzylamine, triethanolamine, and pyridine.

Alkali metal hydroxides and basic nitrogen compounds are generally used as catalysts for the reaction to obtain phenolic resol resins, but the structural properties described in the present invention obtained using alkali metal hydroxides a resin having;
When comparing resins with the structural characteristics described in the present invention obtained using basic nitrogen compounds, a significant difference appears in the stability of the emulsion, and in the case of basic nitrogen compounds,
The alkali metal hydroxide had excellent stability for more than one month, whereas the alkali metal hydroxide formed a precipitate within a few days.

This is considered to be because the alkali metal ions of the alkali metal hydroxide remaining in the resin have an adverse effect on the stability of the emulsion.

The resin suitable for the emulsion used in the present invention can be obtained by carrying out the usual phenol-formaldehyde reaction, but in this case, it is necessary to use a basic nitrogen compound such as ammonia or amines as a reaction catalyst. As a structural characteristic of the produced resin, the number average molecular weight Mn = 300 ~
It is necessary to control the reaction so that the weight average molecular weight is 650. For this purpose, phenols and their phenols 1
A heating reaction may be carried out using 1.0 to 1.5 moles of formaldehyde per mole in the presence of the above-mentioned basic nitrogen compound as a reaction catalyst, but the components other than the reaction catalyst are not limited to this.

Phenolic resins suitable for the present invention include those modified on the i-pillar side. Modifiers include aniline, melamine, dicyandiamide, guanidine, benzoguanamine, acetoguanamine, urea, deourea, ethylene urea, benzenesulfonamide, polyamide, alkylbenzene formaldehyde resin, xylene resin, silicone resin, tung oil, linseed oil, and the like. To obtain a modified phenolic resin, phenols, aldehydes, and a modifier can be simultaneously charged and reacted, or the phenol and formaldehyde can be reacted, and then the modifier can be added (if necessary, the aldehyde can be added). After reacting with the modifier and aldehydes, add phenols (adding aldehydes as necessary) and react further, or react with phenols and aldehydes and After separately reacting the modifier and aldehydes,
A method is used in which they are mixed or reacted after mixing (adding aldehydes as necessary), and usual temperature and pi-i control are carried out in all reactions.

In order to obtain a stable emulsion in the present invention, the balance between hydrophilicity and hydrophobicity of the resin must be appropriate, and the molecular weight, molecular weight distribution, and methylol group weight of the resin are major factors in determining that balance. , the resin is required to have the structural properties described in the present invention.

As for the structural characteristics of the phenolic resin used in the present invention, when the number average molecular weight is Mn < 300 and the weight average molecular weight is Mw < 1500, that is, when the molecular weight is small, the hydrophilicity of the resulting resin becomes strong and emulsification and dispersion becomes difficult. It becomes difficult. On the other hand, if the number average molecular weight is Mn > 650 and the weight average molecular weight is Fvfw > 8000, that is, if the molecular weight is large, the hydrophobicity of the resulting resin will be too strong, resulting in poor emulsion stability or dispersion. It may disappear.

If the molecular weight is too large, there will be no time available for curing when the resin is applied to a molded article, which may cause problems in the use of the resin. In addition, the number average molecular weight is Mn = 300 to 6, but when the nose average molecular weight is Mw < 1500 or Mw > 8000, or the weight average molecular weight is Mw = 1500 to 8000.
However, if the number average molecular weight is Mn < 300 or Mn
> 650 (7), the molecular weight distribution is wide, and if a highly hydrophilic resin component and a highly hydrophobic resin component are mixed, it becomes very difficult to emulsify and disperse each component together. This is because when resin components have different balances of hydrophilicity and hydrophobicity, appropriate emulsifiers are required for each resin component, and if resin components with large differences in the balance of hydrophilicity and hydrophobicity are mixed, the emulsifier will remove all the resin components. This is because emulsification and dispersion cannot be achieved.

If it is < 0.30, the hydrophilicity of the resin becomes too weak, resulting in poor emulsion stability and dispersion. It becomes too strong, making emulsification and dispersion difficult.

Note that Mn and Mw used here are those measured by gel permeation chromatography.

The measurement conditions for GPC are as follows.

Separation column: Polystyrene gel with an average pore diameter of 10 angstroms (hereinafter abbreviated as A), packed with 100% inner diameter 7.
A column consisting of four columns connected in series, each with a length of 5m and a length of 60α.・ Theoretical plate number of separation column: 30c! 8000 plates per L, precolumn: inner diameter 7.5 II@, length 5c filled with polystyrene gel with a theoretical plate number of 8000 plates per 301 or more
One column of WL.

Eluent: Tetrahydrofuran Flow rate: 14/min Separation column temperature: 40°C Sample injection material: 300 μl of a tetrahydrofuran solution with a weight coefficient of approximately 1.1, and monodisperse standard polystyrene was used to create a calibration curve for molecular weight standardization.

In the present invention, the GPC device used for molecular weight measurement is a model 801 device manufactured by Toyo Soda Kogyo Co., Ltd., and the GPC separation column is TSk-GELG-1000H manufactured by Toyo Soda Kogyo Co., Ltd.
,,G-2000HG-2000H.

and G 3000 Ha. Moreover, the precolumn is GH8P.

In calculating the molecular weight, the area of the chromatogram sections was treated as follows. Unreacted monomers are excluded and not used in molecular weight calculations. When calculating the molecular weight, consider the spread of the peak width as the elution count starting point at the peak apex of the overlapping peaks (50 to 60 counts) of 3-methyl/6-methylolphenol and 2-methyl/3-methylolphenol. A section of the chromatogram was used in which the end point was an elution count that was 2 counts higher than the minimum elution count. The quadrature of each section was performed by measuring the peak height for each count interval. However, only in the case of the peaks of 3-methyl/6-methylolphenol and 2-methylolphenol (50 to 60 counts), the peak height at the peak apex was used.

The NMR measurement conditions are as follows.

Solvent: Acetone-d6 or dimethyl sulfoxide
d6, Temperature: Room temperature, Sample concentration and amount: Approximately 20-30% by weight solution in 300μ
I used it.

Furthermore, in order to distinguish between methylol beak and dimethylene ether beak, the methylol group was acetylated before measurement.

The emulsifier used in the present invention includes water-soluble polymer compounds, such as polyvinyl alcohol, hydroxyethyl cellulose, and polyacrylamide. Among these, there are fully saponified polyvinyl alcohols, partially saponified polyvinyl alcohols, and those modified with surface-active functional groups, hydroxyethyl cellulose with various degrees of polymerization, and polyacrylamide with anionic It also includes sexual and cationic types.

Further, if necessary, a surfactant can be used in combination with these water-soluble polymer compounds.

As surfactants, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether,
Examples include polyquine ethylene alkyl ester, polyoxyethylene polyoxypropylene ether, and polyoxyethylene sorbitan alkyl ester.

The amount of emulsifier to be added is 0.000% based on the solid content of the phenolic resin.
It is 5 to 10% by weight, preferably 1 to 5% by weight. 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.

Aqueous phenolic resol resin in the present invention □
The emulsion manufacturing method is similar to the general emulsion manufacturing method, and an emulsifier is added before, during, or after the reaction of the phenolic resin, and water is added while stirring and mixing. This results in an aqueous emulsion containing a resin solids content suitable for use.

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 1 750 g of phenol and 800 g of 37-thiformin were mixed into 2
Heating reaction in the presence of 5% aqueous ammonia 201/Mn = 350, Mw = 1820, QM
-0.40 produced resin 1000 #, saponification degree 8
300 g of a 10 wt % aqueous solution of polyvinyl alcohol having a polymerization degree of 1700 and 8% 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.

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 α-cellulose 120 parts zinc stearate 3 parts hexamethylenetetramine
0.5 parts by weight ((b) Cross-wire method: Cross-wire at 60°C for 5 minutes using a Sigma vane-type Nigu.

(c) Drying conditions Dry at 110°C for 15 minutes using hot air drying method.

2) Molding conditions Molding pressure 300 Ky/cr & Molding temperature 160℃ Molding time 4 minutes Example 2 850g of phenol and 80g of phenol and 80g of formaldehyde
0g in the presence of 30g of 40% dimethylamine aqueous solution, resulting Mn = 460, Mw-327
0, QM = 0.42 at 1000 F of the produced resin,
200 g of a 10 weight aqueous solution of polyvinyl alcohol having a degree of saponification of 98% and a degree of polymerization of 2400 and 20 g of polyoxyethylene nonylphenyl ether were added and mixed with stirring 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 using the same formulation as in Example 1, and the performance of the molded product obtained is shown in Table 1.

Example 3 Meta and para-cresol 72011 and 37% formalin 700.9 were heated and reacted in the presence of 25% aqueous ammonia 101, resulting in Mn = 520, Mw = 7.
360, QM = 0.45 produced resin 1000 I
A 10% by weight aqueous solution 4001 of hydroxyethyl cellulose with 3 moles of added ethylene oxide and a degree of cellulose polymerization of 400 was added to i, 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.

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 Phenol 750I and 37% formalin 950Ii were heated and reacted in the presence of 30g of 25% ammonia water, resulting in Mn = 720, Mw = 9740, Q
To 1000.9 of the resulting resin with M = 0.40, 1000% of the same polyvinyl alcohol aqueous solution as in Example 1 was added.
Ii was added, and the mixture was stirred and mixed at 40°C for 10 minutes. Immediately add room temperature water while stirring to obtain a resin solid content of 40% by weight.
An emulsion was obtained.

However, this emulsion formed a precipitate within 2 days and had poor stability. 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: The same reaction as in Example 1 was carried out using sodium hydroxide as a catalyst instead of ammonia to produce resin 1000 F.
The same operation was carried out using a 10% by weight aqueous solution of polyvinyl alcohol similar to that used in Example 1 and adding an amount of 1000 F, but no emulsion was obtained.

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

Claims (1)

[Claims] Number average molecular weight Mn = 300 obtained by reacting phenols and formaldehyde in the presence of a basic nitrogen compound
~650, weight average molecular weight Mw = 1500~ A phenolic resin aqueous emulsion in which a sol resin is dispersed in water in the presence of an emulsifier.