JP2021161156A - Phenolic resin composition - Google Patents

Abstract

To provide a composition that comprises a phenolic resin and is used as a binder for a refractory, and has liquid properties before firing and shows a high residual carbon rate of 50% or more after firing.SOLUTION: A phenolic resin composition comprises a phenolic resin synthesized to have an F/P ratio of 0.2-0.9, and water and/or a phenol monomer, but is free of ethylene glycol. Relative to 100 pts.wt. of a phenolic resin solution with a solution viscosity of 50-80,000 mPa s, 10-38 pts.wt. of hexamethylene tetramine is contained.SELECTED DRAWING: None

Description

The present invention relates to a phenol resin composition used as a binder for refractories, which is liquid in nature and has a high residual carbon content after firing.

Materials such as metal, glass and cement are melted at high temperatures. In particular, in the case of metal, it is melt-processed at 1000 ° C. or higher, and the material that comes into direct contact with these solutions is required to have heat resistance and chemical erosion resistance.

Previously, refractories were composed of only metal oxides or carbon, but from the viewpoint of performance, the current mainstream is composed of composite materials of metal oxides and carbon. When firing refractories, tar pitch is mainly used as a binder in Europe, and phenolic resin is mainly used in Japan.
It is desirable that the binder is in a liquid state because there is a kneading step before firing, and the gas during firing forms open pores and causes deterioration of the performance of the molded product after firing, so that gas generation is small, that is, after firing. Phenol resin, which is a binder with a high residual coal ratio, is required.
In order to increase the residual coal ratio, it is advantageous that the binder properties before firing are solid, but a liquid one is required in terms of handling.

JP-A-58-19351 JP-A-2007-153977 JP-A-2007-13881 JP-A-2007-138883 JP-A-2007-246594 JP 2006-273602

Patent Document 1 is a liquid phenol resin for refractories. The properties before firing were liquid, but there was room for improvement in the residual coal ratio. Patent Document 2 relates to cured phenol resin particles for carbides and a method for producing the same, and particularly, cured phenol resin particles for carbides useful as fillers, raw materials for various carbon materials, and the like, and hardened phenol resin particles for carbides. It is a publication on a method capable of producing it advantageously. An example of a phenol resin aqueous dispersion is shown, but since it is a dispersed product, there is a risk of separation.

Patent Documents 3 and 4 are similar publications, and are phenolic resins that have an excellent balance of curing rate and heat resistance and do not cause curing inhibition even when a basic filler is blended, without substantially using hexamethylenetetramine. It is a publication concerning a composition. The property before firing was solid, and it was difficult to use it as a refractory firing binder.
Patent Document 5 is a publication relating to a resin composition having a higher residual coal ratio than a conventional phenol resin and excellent mechanical strength of a cured product. Patent Document 6 is a publication relating to a composition for a carbon material capable of obtaining a carbon material exhibiting high charge / discharge efficiency and high charge / discharge capacity when used as a negative electrode material for a lithium ion secondary battery. Both show relatively high residual coal rates, but they were also solid before carbonization and were unsuitable as refractory firing binders.

As a phenol resin used as a binder for refractories, it is necessary to obtain a composition showing a high residual coal ratio, which is liquid before firing and has a residual carbon ratio of 50% or more after firing.

As a result of diligent studies by the inventors, it contains a phenol resin synthesized with an F / P ratio of 0.2 to 0.9, water and / or a phenolic monomer, and contains ethylene glycol. Instead, a phenol resin composition containing 10 to 38 parts by weight of hexamethylenetetramine was provided with respect to 100 parts by weight of a phenol resin solution having a solution viscosity of 50 to 80,000 mPa · s.

Since it is liquid before firing, it is easy to knead the composite material of metal oxide and carbon, and the residual carbon ratio after firing is high, the formation of open pores is small and the performance of the molded product after firing is improved. be able to.

An example of a phenol resin used as a binder for refractories is shown.
In addition, the phenol resin maker performs the synthesis of the phenol resin, the addition of other components, and the stirring, the compounding product is mixed with hexamethylenetetramine, the metal oxide and carbon are added, the mixture is kneaded, and the mixture is fired. It is a general usage pattern that the process of producing a refractory molded product is performed by a refractory manufacturer.

Examples of the phenols (P) include phenol, cresol, xylenol, nonylphenol, paraterchary-butylphenol, para-secondary-butylphenol, naphthol, catechol, resorcinol, hydroquinone, methylhydroquinone, dimethylhydroquinone and the like.
From the viewpoint of availability, a suitable material includes phenol.

As the aldehydes (F), for example, formaldehyde, paraformaldehyde, trioxane (methoformaldehyde) and the like can be used alone or in combination of two or more.
Further, as the aldehydes (F), those dissolved in water can also be used. A more preferred material is formaldehyde, with 50% -formaldehyde being convenient.

The charging ratio of phenols (P) and aldehydes (F) is more preferably F / P = 0.2 to 0.9, where P is the molar ratio of phenols and F is the molar ratio of aldehydes. It is good to prepare at 0.25 to 0.85.

Phenols (P) and aldehydes (F) become novolak resin when reacted with an acid catalyst, and resol resin when reacted with an alkali catalyst. Any of them can be used as a phenol resin used as a binder for refractories, but it is more preferable to use the former.
As the acid catalyst for producing the novolak resin, for example, an acid catalyst such as oxalic acid, zinc acetate, boric acid, phosphoric acid, sulfuric acid, and paratoluenesulfonic acid can be used. The amount added is 0.05 to 2 parts by weight, more preferably 0.1 to 1 part by weight, based on 100 parts by weight of the phenols (P).
These catalysts can be added directly, but can also be added by dissolving them in a small amount of water.

The method for synthesizing the novolak resin is not particularly limited. For example, a method in which phenols (P), aldehydes (F), and an acid catalyst are collectively charged and reacted, or a method in which phenols (P) and an acid catalyst are charged and then predetermined. Examples thereof include a method of adding aldehydes (F) at the reaction temperature of.
The reaction temperature is 50 ° C. to 150 ° C., more preferably 60 ° C. to 140 ° C. If the temperature is lower than 50 ° C, the reaction proceeds slowly, and if the temperature exceeds 150 ° C, there is a concern that phenols and aldehydes may be scattered and the catalytic activity may be lowered, which is not preferable.
The reaction time is not particularly limited and may be adjusted according to the amounts of aldehydes and catalysts and the reaction temperature.
The molecular weight can be adjusted by controlling the amount of aldehydes. The end point of the reaction can be determined by tracking the reaction with GPC or the like and eliminating the change in molecular weight.
After completion of the reaction, water is concentrated to complete the synthesis. As the conditions for concentrating water, it is preferable to concentrate at 120 to 200 ° C., more preferably 140 to 180 ° C. at normal pressure. When ethylene glycol is added in the formulation of the next step, it is preferable to concentrate under the above temperature conditions under a reduced pressure of 5000 to 8000 Pa, more preferably 6000 to 7000 Pa.
Further, if the conditions are met, it is possible to proceed directly to the firing step without performing concentration.

The phenol resin obtained by the above synthesis is solid because it concentrates water. As described above, the phenol resin used as a binder for refractories is preferably in a liquid state because it has a kneading step before firing. Therefore, it is better to dissolve the solid phenol resin.
Examples of the compound to be blended and dissolved include water and phenolic monomers. Examples of the phenolic monomer include phenol, cresol, xylenol, nonylphenol, paraterchary-butylphenol, para-secondary-butylphenol, naphthol, catechol, resorcinol, hydroquinone, methylhydroquinone, dimethylhydroquinone and the like, which are more preferable. Examples of the phenolic monomer include phenol.
The amount of water and phenolic monomers added is 0 to 10 parts by weight, more preferably 0 to 7 parts by weight, and a single amount of phenols, based on 100 parts by weight of the phenol resin obtained by synthesis. In the case of a body, it is preferable to add 0 to 50 parts by weight, more preferably 0 to 25 parts by weight to dissolve the phenol resin obtained by synthesis.
The phenolic resin obtained by synthesis can be dissolved in water and / or one of the phenolic monomers. The final viscosity is 50 to 80,000 mPa · s, more preferably 100 to 90,000 mPa.s.

The amount of hexamethylenetetramine added is 10 to 38 parts by weight, more preferably 12 to 35 parts by weight, based on 100 parts by weight of the phenol resin solution whose viscosity has been adjusted by blending.
The firing step after this can be produced by a conventional method.

Hereinafter, the present invention will be described in more detail with reference to Examples, Comparative Examples, Test Examples and the like, but specific examples are shown, and the present invention is not particularly limited thereto.

<Synthesis of phenolic resins 1-28>
In the ratios shown in Tables 1 and 2, phenol and 50% -formaldehyde were charged in a flask, and in Synthesis Examples 1, 2 and 7 to 22, 24 to 28, oxalic acid dissolved in water was added, and the temperature was 100 ° C. for 3 hours. In Synthesis Examples 3 to 6 and 23, zinc acetate dissolved in water was added, and the mixture was stirred at 100 ° C. for 2 hours and then at 140 ° C. for 1 hour to terminate the reaction. After completion of the reaction, water was concentrated in Synthetic Examples 1-19, 21-23 and 27 at 160 ° C. and normal pressure. Next, in Synthesis Examples 24 to 26 containing ethylene glycol, water and unreacted free phenol were concentrated at 160 ° C. and 6,666 Pa.
Since Synthesis Example 20 was not concentrated at all and had a viscosity of 5,700 mPa · s, which was within an appropriate range, it was used as the liquid of Formulation Example 20.

<Preparation of Formulation Examples 1-28>
100 g of phenol resin 1-28, water, phenol, and ethylene glycol were weighed at the ratios shown in Tables 3 and 4, and stirred until uniform to prepare a solution of Formulation Examples 1-28.

<Measurement method of free phenol>
Product name manufactured by SHIMADZU; GC-2014, product name manufactured by GL Sciences: PEG-20M was used, and measurement was performed by gas chromatography using acetophenone as a standard substance.
The results are shown in Tables 3 and 4.

<Organic components and active ingredients excluding water>
The organic components excluding water in Tables 3 and 4 are the ratio of phenol resin, phenol, and ethylene glycol to the total.
The active ingredient is an active ingredient that contributes to the residual coal ratio, and is a ratio obtained by removing ethylene glycol from the organic component. Both are expressed as percentages.

<Measurement of water content>
The water content in Tables 3 and 4 was measured using a product name: MKV-710 manufactured by Kyoto Denshi Kogyo Co., Ltd.

<Viscosity measurement>
The viscosities in Tables 3 and 4 were measured according to JIS-Z-8803. The viscometer was a cone-plate type viscometer manufactured by Toki Sangyo Co., Ltd., trade name: TVE-25H. Further, as the measurement conditions, the measurement was performed at 3 ° R14, 0.5 to 100 rpm, 60 seconds value, and 25 ± 1 ° C., and the measured value was taken as the viscosity.

<Preparation of solutions of Examples 1 to 20 and Comparative Examples 1 to 8>
Weigh 100 g of Formulation Examples 1 to 28 and hexamethylenetetramine at the ratios shown in Tables 5 and 6, and stir until they are visually uniform, and mix the solutions of Examples 1 to 20 and Comparative Examples 1 to 8. Made.

<Measurement of residual coal rate>
Measurement was performed according to JIS-K-6910: 2007 5.20 fixed carbon content. No preheating was performed. The results are shown in Tables 5 and 6.
As for the evaluation result, the residual coal ratio of 50% or more passed, and less than 50% failed.

It contains phenol resin synthesized with an F / P ratio of 0.2 to 0.9, water and / or phenolic monomers, does not contain ethylene glycol, and has a solution viscosity of 50 to 80,000 mPa. Examples 1 to 20, which are phenol resin compositions containing 10 to 38 parts by weight of hexamethylenetetramine with respect to 100 parts by weight of the phenol resin solution of s, have a residual carbon content of 50% or more and are all acceptable. rice field.

Comparative Example 1 in which 38.7 parts by weight of hexamethylenetetramine was added to a solution having a solution viscosity of 50 to 80,000 mPa · s was rejected with a residual coal ratio of 49%. It is considered that this is because hexamethylenetetramine was decomposed a lot. Comparative Examples 2 to 4, in which the amount of hexamethylenetetramine added to the solution having a solution viscosity of 50 to 80,000 mPa · s was as small as 9.7, also had a residual coal ratio of less than 50, which was unacceptable. Hexamethylenetetramine has been shown to have an optimal addition.

Comparative Examples 5 to 7 to which ethylene glycol was added also had a residual coal ratio of less than 50, which was unacceptable. It was shown that ethylene glycol should not be added.
Comparative Example 8 in which the solution viscosity exceeded 80,000 mPa · s also had a low residual coal ratio, indicating that the phenol solution had an optimum viscosity.

Claims (1)

Phenol resin synthesized with an F / P ratio of 0.2 to 0.9 and
With respect to 100 parts by weight of a phenol resin solution containing water and / or a phenolic monomer, not containing ethylene glycol, and having a solution viscosity of 50 to 80,000 mPa · s.
A phenolic resin composition containing 10 to 38 parts by weight of hexamethylenetetramine.