JP3305828B2 - Binder composition for refractories - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder composition for a refractory, and more particularly to a binder composition for a refractory using a basic aggregate as a main material for reducing expansion and cracking of the refractory. It is about.

[0002]

2. Description of the Related Art Tar and pitch have long been used as binders for refractories forming carbon bonds. However, in recent years, many refractories mainly using a phenolic resin as a binder have been used because, for example, room temperature kneading of the raw material is possible, the drying strength of the refractory is large, and the working environment during the production of the refractory is improved. Has become. As phenolic resin binders for refractories, novolak-type and resol-type liquid or powdery resins are used alone or in combination. As a typical use example of the resin, in the case of a novolak type phenol resin, the powder resin containing hexamethylenetetramine is ethylene glycol,
It is used together with a wetting agent such as diethylene glycol, methyl alcohol and ethyl alcohol, or used in combination with a liquid resol type phenol resin. A liquid resin obtained by dissolving a novolak type phenol resin in a solvent such as ethylene glycol in advance is often used in combination with hexamethylenetetramine during kneading.

In the case of a resol type phenol resin, a water-soluble liquid resin or a solvent type liquid resin dissolved in a solvent such as ethylene glycol may be used alone,
Alternatively, these liquid resins are used in combination with a powdered novolak phenol resin. However, refractory bricks using a conventional phenolic resin as a binder, particularly when a basic aggregate such as magnesia or dolomite is used as a main material, expands by absorbing moisture in the resin or moisture in the air, and tends to cause cracking. There is a disadvantage that.

[0004]

The inventors of the present invention have conducted intensive studies to overcome this drawback, and as a result, have found that a novolak-type phenol resin, an epoxy resin having at least two epoxy groups in one molecule, and a boiling point at normal pressure can be obtained. 75 ℃ or more of d
The present inventors have found that the use of a binder containing stells can reduce the expansion and crack generation of a refractory brick, and have reached the present invention.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a novolak type phenol resin and an epoxy resin having a boiling point of 7 at normal pressure.
The present invention relates to a binder composition for refractories, which contains an ester having a temperature of 5 ° C. or higher.

The novolak type phenol resin used in the present invention is generally prepared by converting an acid substance such as oxalic acid, hydrochloric acid or sulfuric acid or an organic metal salt as a catalyst to a phenol and formaldehyde in a molar ratio of formaldehyde to phenol of 0.3.
~ 1.0. Phenols used as a raw material of the novolak type phenol resin include phenol, cresol, xylenol, para-tert-butylphenol, paraoctylphenol, paranonylphenol, paracumylphenol, bisphenol A, etc., and these are used alone or in combination of two or more. it can. On the other hand, as aldehydes, formalin is usually used, but aldehyde-generating substances such as paraformaldehyde and trioxane, and benzaldehyde can also be used. Further, when producing a novolak-type phenol resin, it is more preferable that the phenol resin is modified with an aromatic hydrocarbon resin such as a xylene resin or a mesitylene resin because the amount of phenolic hydroxyl groups that contribute to moisture absorption can be reduced.

In the present invention, at least two molecules per molecule are used.
Examples of the epoxy resin having two or more epoxy groups include bisphenol type, aliphatic type, and novolak type, and these can be used alone or in combination of two or more. The equivalent ratio of the hydroxyl group of the novolak type phenol resin to the epoxy group of the epoxy resin is 0.5 to 1.5, and preferably 0.7 to 1.3. When the compounding equivalent ratio is out of this range, the curing speed is slow and a sufficient degree of curing cannot be obtained.

As the organic solvent used in the present invention, glycols such as ethylene glycol and diethylene glycol, and alcohols such as methyl alcohol and ethyl alcohol are not preferred. If these solvents are used for aggregates made of basic substances, the hydroxyl groups and the aggregates thereof have a sensitive reaction to deteriorate the state of the clay, or cause moisture absorption and cracks. .

Esters having a boiling point of 75 ° C. or higher for use in the present invention
The class is, for example, the following compound. Ethyl acetate,
Isopropyl acetate, isobutyl acetate, n-butyl acetate,
Glycol diacetate, monoacetin, diacetin, triacetin, γ-butyrolactone, dimethyl glutarate, dimethyl succinate, dimethyl adipate, dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, cresyl diphenyl phosphate, ethylene carbonate, propylene carbonate, etc. Esters

The refractory binder composition of the present invention can be sufficiently used without using a curing accelerator in particular.
The refractory properties can be improved by using a curing accelerator together. As the curing accelerator, hexamethylenetetramine, tertiary amine, imidazoles, organic phosphine compounds, and the like can be used. Among these curing accelerators, hexamethylenetetramine, tertiary amine, imidazoles, and the like are used at room temperature. However, the effect as a hardening accelerator is large, and as a result, the time-dependent change of the kneaded clay is not preferable. On the other hand, an organic phosphine compound having low reactivity at room temperature is particularly preferable from the viewpoint of workability. Also,
Hardening accelerator in advance with solid novolak 1/1 to 1/20,
Preferably, mixing and pulverization at a ratio of 1/3 to 1/15 followed by mixing increases the dispersibility of the curing accelerator, and achieves high performance with a smaller amount. If the solid novolak compounding ratio is lower than this, sufficient dispersibility may not be obtained. On the other hand, if the compounding ratio is higher than this, the ratio of novolak increases, and sufficient curing may not be obtained.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to embodiments. All “parts” and “%” described in the text indicate “parts by weight” and “% by weight”. Example 1 1000 parts of phenol, 677 parts of 37% formalin and 10 parts of oxalic acid were charged into a resin reactor equipped with a stirrer, a reflux condenser and a thermometer, and reacted for 3 hours under reflux conditions. Then, the water content is less than 1% and the amount of free phenol is 3
Dehydration and dephenol removal were carried out under reduced pressure until the concentration became ７7%. Thereafter, the inside of the system was returned to normal pressure, and 860 parts of dimethyl glutarate and liquid epoxy resin A (viscosity 140 P / 25
And 1,940 parts of an epoxy equivalent of 190 ° C. were added and mixed to obtain 3870 parts of a binder composition for refractories. This composition had a compounding ratio of hydroxyl group to epoxy group of 1.0 and a viscosity of 130 P / 2.
5 ° C.

Example 2 In a resin reactor equipped with a stirrer, reflux condenser and thermometer, 1000 parts of phenol, 37 parts
% Of formalin and 10 parts of oxalic acid were charged and reacted under reflux conditions for 3 hours. Then, dehydration and dephenol removal were performed under reduced pressure until the water content became 1% or less and the amount of free phenol became 3 to 7%. Thereafter, the pressure in the system was returned to normal pressure, and 860 parts of dimethyl glutarate and liquid epoxy resin A (viscosity 1)
1550 parts of 40 P / 25 ° C., epoxy equivalent 190) was added and mixed to obtain 3480 parts of a binder composition for refractories. This composition had a mixing ratio of hydroxyl group to epoxy group of 0.8 and a viscosity of 140 P / 25 ° C.

Example 3 In a resin reactor equipped with a stirrer, a reflux condenser and a thermometer, 1000 parts of phenol, 37 parts
% Of formalin and 10 parts of oxalic acid were charged and reacted under reflux conditions for 3 hours. Then, dehydration and dephenol removal were performed under reduced pressure until the water content became 1% or less and the amount of free phenol became 3 to 7%. Thereafter, the pressure in the system was returned to normal pressure, and 2650 parts of dimethyl glutarate and 4800 parts of solid epoxy resin B (softening point: 64 ° C., epoxy equivalent: 470) were added and mixed to obtain 8520 parts of a binder composition for refractories. This composition had a compounding ratio of hydroxyl group to epoxy group of 1.0 and a viscosity of 150
P / 25 ° C.

Example 4 In a resin reactor equipped with a stirrer, a reflux condenser and a thermometer, 1000 parts of phenol and 250 parts of xylene resin (Nicanol H, manufactured by Mitsubishi Gas Chemical Company) were used.
Then, 5 parts of oxalic acid was added, and the mixture was reacted under reflux conditions for 3 hours. Thereafter, 5 parts of oxalic acid and 646 parts of 37% formalin were charged and reacted under reflux conditions for 2 hours. Then moisture 1
%, And dehydration and dephenol removal were performed under reduced pressure until the amount of free phenol became 3 to 7%. Thereafter, the inside of the system was returned to normal pressure, and 1000 parts of propylene carbonate and liquid epoxy resin A (viscosity 140 P / 25 ° C., epoxy equivalent 190) 22
80 parts were added and mixed to obtain 3540 parts of a binder composition for refractories. This composition had a mixing ratio of hydroxyl group to epoxy group of 1.0 and a viscosity of 120 P / 25 ° C.

Comparative Example 1 In a resin reactor equipped with a stirrer, a reflux condenser and a thermometer, 1000 parts of phenol, 37 parts
% Of formalin and 10 parts of oxalic acid were charged and reacted under reflux conditions for 3 hours. Then, dehydration and dephenol removal were performed under reduced pressure until the water content became 1% or less and the amount of free phenol became 3 to 7%. Thereafter, the pressure in the system was returned to normal pressure, and 730 parts of ethylene glycol was added and mixed to obtain 1800 parts of a novolak-type binder composition. This composition has a viscosity of 80 P /
25 ° C.

<Practical test> Coarse-grade dolomite clinker (particle size: 1 to 3 mm) 600 parts, fine powder of magnesia clinker (particle size: 0.3 mm or less) 300 in an experimental mixer
Parts, 100 parts of phosphorous graphite, and 40 parts of the above binder composition, pulverized and mixed with 1 part of triphenylphosphine or triphenylphosphine as a curing agent in 1/10 ratio of solid novolak having a melting point of 84 ° C. 4 curing accelerators
Parts and Comparative Example, 4 parts of hexamethylenetetramine was added and kneaded at room temperature (25 ° C.) for 60 minutes to obtain a kneaded material.
These kneaded kneaded materials were exposed to the air and allowed to stand. After a predetermined time, 130 g of the kneaded material was charged into a 15 × 25 × 100 mm mold, molded under a pressure of 1000 kg / cm ² , and dried at 170 ° C. for 16 hours to prepare a test piece. The dimensional ratio and bending strength of these test pieces were measured. Table 1 shows the results.

[0017]

[Table 1]

As is clear from Table 1, when a liquid novolak resin containing ethylene glycol as a solvent was blended as in Comparative Example 1, the test piece had a large expansion and many cracks were generated. The bending strength after drying also showed a considerably low value. On the other hand, in Examples 1 to 4, there was almost no expansion of the test piece, and the bending strength after drying showed a high value.

[0019]

According to the present invention, a novolak type phenol resin, an epoxy resin and an ester having a boiling point of 75 ° C. or more at normal pressure are blended to reduce the expansion and crack generation of a refractory brick made of a basic aggregate as a main material. The product binder composition is obtained.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 63/00-63/10 C04B 35/64 C08G 59/62 C08K 5/10 C08L 61/06-61 / 14

Claims (3)

(57) [Claims] 1. A refractory bond comprising a novolak-type phenol resin, an epoxy resin having at least two epoxy groups in one molecule, and an ester having a boiling point of 75 ° C. or more at normal pressure. Composition. 2. The refractory binder composition according to claim 1, wherein an organic phosphine compound is used as a curing accelerator. 3. The refractory binder composition according to claim 1, wherein the novolak type phenol resin is modified with an aromatic hydrocarbon resin such as a xylene resin or a mesitylene resin.