JPS58204015A - Production of binder for external wall material - Google Patents

Abstract

PURPOSE:To produce the titled binder excellent in water and weather resistance, by using a novolak phenolic resin prepared by reacting a substituted phenol/ phenol mixture with a formaldehyde in the presence of a bivalent metal salt catalyst. CONSTITUTION:A novolak phenolic resin is obtained by effecting an addition reaction between 1mol of a mixture containing a substituted phenol (e.g., m- cresol) and phenol at a ratio of 10/90-79/30, and 0.1-0.9mol of a formaldehyde (e.g., trioxane) at 100-140 deg.C for 1-6hr in the presence of a bivalent metal salt (e.g., zinc acetate) as a catalyst and dehydrating the reaction mixture under reflux at 110-170 deg.C. Then, this phenolic resin is mixed with a curing agent (e.g., hexamethylenetetramine) to form a binder. Then, an external wall material is obtained by mixing this binder with an inorganic base and pressure-molding the mixture.

Description

[Detailed description of the invention] The present invention can be dispersed and mixed into an organic or inorganic base material.

This invention relates to a novolac type phenolic resin for fixing and coating, and particularly to a method for producing a modified novolac type phenolic resin most suitable as a binder for exterior wall materials.

In general, novolak-type phenolic resins are produced by condensing phenols and formaldehydes in the presence of an acidic catalyst such as hydrochloric acid, sulfuric acid, oxalate-paratoluenesulfonic acid, or the like. Here, when a basic catalyst is used to carry out a condensation reaction, a resol type phenol resin is obtained. However, since this resol type phenolic resin is generally liquid,
Except for specific uses such as lamination molding, it is unsuitable for molding methods in which dry manufacturing is the mainstream. Therefore, powdered novolac type phenolic resin is suitable as a binder for exterior wall materials that uses a dry manufacturing method.

Novolak-type phenolic resin is widely used as a binder for exterior wall materials to improve water resistance and weather resistance, but the base material for this exterior wall material is an inorganic material that is nonflammable. It is being said. Also, to maintain the strength and insulation effect of the exterior wall materials.

However, some of these inorganic materials contain basic substances and metal oxides (e.g. Cao, MgO, etc.). ) etc., it impairs the properties of the binder and significantly deteriorates the weather resistance and water resistance of the exterior wall material product after molding. I often end up leaving things unfulfilled.

In order to mold an exterior wall material under arbitrary pressure molding conditions using a novolak type phenolic resin and a hardening agent, hexamethylenetetramine, and to improve weather resistance and water resistance, it is necessary to combine the above binder and an inorganic base material. It is necessary to uniformly disperse and mix the material over a wider area and in more detail, and to cure it sufficiently with heat. To this end, there are methods of adding hexamethylenetetramine, a curing agent, in an amount greater than the theoretical amount required for curing a novolac type phenolic resin with an arbitrary average molecular weight, or addition of benzoic acid, phthalic acid, succinic acid, etc. A small amount of a substance called a hardening accelerator such as anhydride is added.

Attempts have also been made to increase the apparent curing speed.

However, even if these formulations speed up heat curing and perform pressure molding, a large amount of decomposed gas from hexamethylenetetramine is generated during molding and firing, causing bad odors and rashes on workers, and other negative effects on the work environment and the human body. and cause industrial pollution problems. In addition, the increased hydrophilicity of the molded product causes a decrease in strength and discoloration of the exterior wall material, resulting in a significant loss of water resistance and weather resistance. For this reason, a faster-curing 7-volac type phenolic resin is required as a binder for exterior wall materials, and a modified novolac-type phenolic resin that can withstand basic inorganic materials is required to maintain weather resistance for a long time. Become.

The present invention was achieved as a result of intensive research with the aim of providing a binder for exterior wall materials that overcomes the above-mentioned drawbacks as a binder.

The present invention uses divalent metal salts (e.g. zinc acetate, magnesium acetate,
by using zinc borate).

Contains many ortho-substituted methylene structures) (i
It has been discovered that by blending a ghortho-novolac type phenolic resin, the binder and the base material undergo a sufficient thermosetting reaction, and the strength of the exterior wall material is significantly improved.

Furthermore, in order to withstand basic inorganic materials and retain weather resistance for a long time, the high ortho-novolag type phenolic resin is combined with one or more substituted phenols (
For example m-cresol, p-cresol, 3,4-xylenol, 6,5-xylenol.

Modified with m- or p-alkylphenols such as para-octylphenol, para-tert-butylphenol, cashew (cardanol), bisphenol A, paraphenylphenol, etc.), and is significantly more effective than conventional binders for exterior wall materials. This is due to improved weather resistance.

As the formaldehyde used in the present invention, formalin (formaldehyde aqueous solution), paraformaldehyde, trioxane, polyoxymethylene, tetraoxymethylene, and a mixture of these formaldehyde polymers are used, and the amount used is one or two. More than one type of substituted phenols and phenol are contained in a proportion of 0.
1 to 09, particularly preferably 0.4 to 0.8 mol.

The amount of modification used in the present invention is 1 type or 2!11 or more substituted phenols and phenol are 10/90 to 70150
20/80 to 40/60 is particularly preferable.O The feature of the present invention is that when reacting one or more substituted phenols and phenol with formaldehyde, the initial reaction is performed using a divalent metal salt as a catalyst. After the addition reaction is completed, a dehydration reaction step is performed to form a collinear reaction between the substituted phenols and phenol and a high ortho-
By producing more methylene composition of the type, l(igk+
This is a method for obtaining ortho-novolak type phenolic resin.

The reaction temperature is 100 to 140°C for the initial reaction.

After reacting for 1 to 6 hours, dehydration and reflux reaction is carried out at 110 to 170°C, and the resulting reaction product is produced by removing contained water, unreacted phenols, etc. under reduced pressure.

Example-1 500 parts of phenol, 135 parts of bisphenol, 645 parts of formalin (67% formaldehyde aqueous solution), and 165 parts of zinc acetate were charged into a flask equipped with a reflux condenser and reacted under reflux for 1 hour, and then the water content was reduced to 150°C. was removed, unreacted substances were removed under reduced pressure, and the softening point was 95°C.
, a novolac resin having an average molecular weight of 554 was obtained. Add hexamethylenetetramine to this novolac resin to a resin content of 100%.
A binder was prepared by adding 15 parts to each part of the powder and pulverizing and uniformly mixing the mixture.

30 parts of the above binder and flyara', i-
200s, mix glass powder 60@lS, 110m
A molding specific gravity of 0.9 was filled into a frame of 100m x 100mm x 12mm, cured in a heat press (temperature 150℃, press pressure 10Kt/e+4) for 10 minutes, and fired by push-cutting. Created.

This pressure-molded product was subjected to a bending test (normal state, water resistance strength) and a discoloration test in an alkaline aqueous solution.

(Table-1) Comparative Example-1 500 parts of phenol, 628 parts of formalin (67% formaldehyde aqueous solution), and 125 parts of zinc acetate were charged into a flask with a reflux condenser, and the same reaction as in Example-1 was carried out to determine the softening point. A novolac resin having an average molecular weight of 492 was obtained at 95°C.

Comparative Example 2 500 parts of phenol, 345 parts of formalin (37% formaldehyde aqueous solution), and 5 parts of oxalic acid were placed in a flask equipped with a reflux condenser and reacted under reflux for 3 hours.

Then, water and unreacted substances were removed under reduced pressure to reduce the softening point to 95.
A novola resin having an average molecular weight of 514 was obtained.

Example-2 500 parts of phenol, 200 parts of paratertiary-butylphenol, 377 parts of formalin (37-formaldehyde aqueous solution), and 1.75 parts of zinc borate were charged into a flask equipped with a reflux condenser, and reacted under reflux for 2 hours, and then reacted under reflux for 2 hours.
Water content was removed to 0°C, and unreacted substances were further removed under reduced pressure to obtain a novolak resin with a softening point of 98°C and an average molecular weight of 612.

Example-3 500 parts of phenol, 269 parts of bisphenol A, paraformaldehyde (formaldehyde content 85 or more) 9
1 part of zinc borate and 1.75 parts of zinc borate were charged into a flask equipped with a reflux condenser, and reacted at 130°C for 3 hours.

Subsequently, water content was removed to 170°C, and unreacted substances were further removed under reduced pressure to obtain a novolac resin having a softening point of 95°C and an average molecular weight of 564.

Example-4 500 parts of phenol, 67 g of bisphenol Al, paraformaldehyde (formaldehyde content 85% or more) 12
7 parts of zinc borate and 1.50 parts of zinc borate were charged into a flask equipped with a reflux condenser and reacted at 2120°C for 2 hours.

Subsequently, water content was removed to 160°C, and unreacted substances were further removed under reduced pressure to obtain a novolac resin having a softening point of 98°C and an average molecular weight of 620.

Example-5 500 parts of phenol, 135 parts of bisphenol A, paraformaldehyde (more than 85 formaldehyde content) 12
4%, 1.25 parts of zinc borate was charged into a flask with a reflux condenser, and reacted at 125°C for 1.5 hours.
Water content was removed to 0°C, and all unreacted substances were removed under reduced pressure to obtain a novolak resin with a softening point of io'c and an average molecular weight of 603.

Examples 1 to 5 above. Obtained in Comparative Examples 1 and 2.

Table 1 shows the results of pressure molding with a base material using novolak resin and conducting bending strength and alkali resistance tests.

Table-1 Note: The number of days when discoloration was observed is marked with ◎.

Test Methods The bending strength and alkali resistance tests were conducted using the following methods.

(1) Bending strength According to JIS K 6911. Water resistance strength is 5 in pure water
The pressure-molded product was immersed in CRN and the bending strength was determined after 48 hours at room temperature.

(2) Alkali resistance test Created a pressure molded product of 50i+mX100X12 Dragon.

Immerse it in 500 ml of 1% NaOH aqueous solution at room temperature.

The number of days in which the discoloration of the surface of the press-molded product and the discoloration of the NaOH aqueous solution were observed by visual observation was defined as the number of days of discoloration, and the alkali resistance was evaluated.

Note: Unless otherwise specified, numerical values in compounding ratios are in weight%.

128-

Claims (1)

[Claims] The blending ratio of one or more substituted phenols and phenol is substituted phenol/phenol = 10/90.
~70/! A method for producing a binder for exterior wall materials, characterized in that a novolak type phenolic resin is produced by mixing the binder in a proportion of 1 O and reacting it with formaldehyde in the presence of a divalent metal salt catalyst.