JPH08134424A - Binder for structural composite - Google Patents

Abstract

PURPOSE: To provide a binder for a structural composite which can improve the strengths of a structural composite. CONSTITUTION: The binder is obtd. by reacting 1mol of phenol with 1-2mol of formaldehyde in the presence of a catalyst comprising 0.05-0.2mol of caustic soda and 0.01-0.1mol of ammonia and has a number average mol.wt. of 300-600.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a binder used in the production of structural composite materials. Here, the structural composite material, for example, like a composite material called particle board, a matrix material such as wood powder or wood chips is mixed with a binder serving as an adhesive, heated and pressed to form a plate or It is a material shaped like a square rod, and is used as a building construction material such as floor boards, wall boards, and ground boards, and as a material that constitutes a pallet for transportation and storage (top board and girder material). .

[0002]

2. Description of the Related Art Alkali resol type liquid phenol resins have been widely used as a binder for the production of this type of structural composite material. However, the phenolic resin that has been conventionally used for the production of structural composite materials such as particle board is a resol type of low molecular weight (number average molecular weight around 150) mainly composed of mono-methylol-phenol and dimethylol-phenol. Therefore, it tends to be impregnated into the wood chips and the amount of resin in the surface layer of the wood chips, which is the adhesive interface, tends to decrease.Therefore, it is necessary to increase the amount of resin used to increase the strength as a structural composite material. However, there was a problem that the cost was high. Moreover, when such a low molecular weight phenolic resin is used as a binder, the cured resin tends to be slightly fragile, but the strength of the structural composite material is poor.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made in view of such a conventional problem, and impregnates wood chips by increasing the molecular weight of the resol-type phenol resin to make it poorly water-soluble. It is intended to provide a binder for a structural composite material capable of suppressing the increase in the amount of resin in the surface layer of the small wood piece which is an adhesive interface and improving the strength of the structural composite material.

[0004]

The binder for structural composite material of the present invention which achieves the above object is obtained by adding 1 to 2 moles of formaldehyde to 1 mole of phenol and caustic soda 0.05 to 0. Add 2 mol and 0.01 to 0.1 mol of ammonia to give a number average molecular weight of 300.
It is characterized in that it is set to ~ 600.

[0005]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

The phenol used in the present invention includes:
Using commercially available ordinary synthetic phenol, 1 to 2 mol of formaldehyde was added to 1 mol of the phenol, and caustic soda 0.05 to 0.2 as a catalyst.
Mol and 0.01 to 0.1 mol of ammonia are added and reacted.

As the formaldehyde used in the present invention, 37% formalin which is an aqueous solution thereof is preferable, and paraformaldehyde which is a polymer may be used. In this case, the purpose can be sufficiently achieved by setting the reaction conditions in consideration of the difference in concentration, the reaction rate, and the like.

It is preferable that the amount of formaldehyde with respect to phenol is 1 to 2 mol per mol of phenol. The reason is that if the amount of formaldehyde is 1 mol or less relative to 1 mol of phenol, the curing time becomes long when the mixture is mixed with a matrix material such as wood powder or wood chips and heated and pressed to form a mixture of 2 mol or more. In addition to the strong formaldehyde odor, the amount of residual formaldehyde increases, so that the amount of gas generated during heating and pressurizing and molding increases and the strength of the structural composite material decreases.

Further, in the present invention, 0.05 to 0.2 mol of caustic soda and 0.01 to 0.1 of ammonia are used as catalysts.
Add moles. In this case, if the amount of caustic soda is less than 0.05 mol, the reaction rate will be slow and the production will take time, so that it will not be practical, and if it is more than 0.2 mol, the reaction will be too fast to control the molecular weight. Similarly, if the amount of ammonia is 0.01 mol or less, it will be difficult to obtain the desired high molecular weight, and if it is 0.1 mol or more, the polymerization will be too fast and the adjustment of the molecular weight will be difficult.

In the production of the structural composite binder according to the present invention, phenol and formaldehyde are weighed and charged into a stainless steel reaction can equipped with a stirrer and equipped with an atmosphere open condenser, and stirred. While 30
C. to 40.degree. C., and then a predetermined amount of caustic soda aqueous solution is gradually added while continuously stirring the reaction can,
The internal temperature is maintained at 45 ° C. And finally, a predetermined amount of ammonia is added, and at 80 ° C to 100 ° C under atmospheric pressure.
The reaction is carried out for 1 to 4 hours while maintaining the above. After completion of the reaction, if necessary, while maintaining the temperature at 50 ° C to 60 ° C, 600 to 750
The solid content can be increased by reducing the pressure to mmHg and dehydrating and concentrating. Then, an appropriate amount of the content in the reaction can is sampled, rapidly cooled to 25 ° C., the viscosity thereof is measured, and the reaction is continued to the target viscosity. When the target viscosity is reached, the contents (binder) in the reaction can are rapidly cooled to 35 ° C. and then transferred to a predetermined container.

Next, specific examples of the present invention will be described. [Example 1] 1,000 g of commercially available phenol and 1,290 g of 37% formalin were placed in a 3 liter three-necked flask equipped with a stirrer and a water-cooled condenser, and 200 g of 40% caustic soda aqueous solution and 25% ammonia water were added to the flask. 50 g was added as a catalyst, and the mixture was heated in a hot water bath at 85 ° C to 95 ° C and allowed to react for 2 hours while keeping the internal temperature at 90 ° C. Then, the mixture was cooled to room temperature to obtain 2500 g of resol type fail resin (binder).

Example 2 After reacting the same proportion as in Example 1 under the same conditions, the internal temperature was 50 ° C. to 60 ° C.
600-750mmH with an aspirator while keeping at ℃
Reduce the pressure to g to evaporate the internal water by boiling, and dehydrate and concentrate for 15 minutes to remove the resol-type fail resin (binder) to 23
00g was obtained.

Next, in order to confirm the performance of the binder for structural composite material according to the present invention, a plate material was formed. That is, 500 g of vulcanized rubber chips obtained by crushing (waste materials of) automobile tires with a crusher to a particle size of 2 mm or less and pine wood chips of 1000 g crushed to a diameter of 2 mm or less and a length of 6 mm or less.
Were mixed, and 200 g of each of the binders prepared in Example 1 and Example 2 was added in terms of solid content, and mixed for 4 minutes with a Shinagawa mixer. Then, this mixture is dried with hot air of 80 ° C to 100 ° C for 15 minutes to adjust the water content to 8 to 12%, and then placed in a mold heated to 150 ° C, and at a pressure of 35 kg / cm ² for 10 minutes. By pressing, a plate material having a length of 200 mm, a width of 200 mm, and a thickness of 15 mm was formed.

Comparative Example For comparison, 1,000 g of commercially available phenol, 37% formalin, 1,290 g and 40% were added.
200 g of an aqueous caustic soda solution was added, and the reaction was performed at the internal temperature of 65 ° C. for 2 hours using the reaction apparatus used in Example 1 to obtain a resol-type phenol resin. Then, using the obtained phenol resin, a plate material having the same size was formed under the same conditions as above.

Thus, the properties of the structural composite binder (phenolic resin) obtained in Examples 1 and 2 and Comparative Example are shown in Table 1 and compared with those of Examples 1 and 2. Table 2 shows the results of measuring the physical properties of each plate material molded using the binder (phenol resin) obtained in the example.

[0016]

[Table 1]

As can be seen from the data shown in Table 1 above, the viscosities of the binders of Examples 1 and 2 are orders of magnitude higher than those of Comparative Examples, and the number average molecular weight is about 3. It is about 5 times more polymer.

[0018]

[Table 2]

From the results shown in Table 2 above, the bending strength and bending Young's modulus of Examples 1 and 2 are improved by 20% or more as compared with those of Comparative Example. Is understood. Further, when the surface of the wooden piece of the plate material was observed with the naked eye, the resin of Examples 1 and 2 seemed to have a larger amount of resin than the resin of Comparative Example.

[0020]

The binder for structural composite materials according to the present invention thus has a molecular weight of 2 to 2 as compared with the conventional binders of this kind.
By making it about 4 times as large as water-insoluble, the amount of resin in the surface layer of the wood chips, which is the adhesive interface, is suppressed by suppressing the impregnation into the wood chips, and when heat-press molding is performed during the production of the structural composite material. Adhesion with the matrix material is improved, and as a result,
Strength can be improved as a binder for structural composite materials.

Claims (1)

[Claims] 1. Addition of 1 to 2 mol of formaldehyde to 1 mol of phenol, 0.05 to 0.2 mol of caustic soda as catalyst and 0.01 to 0.
A binder for structural composite material, wherein 1 mol is added and the number average molecular weight is 300 to 600.