JPH07292218A - Phenol resin composition - Google Patents

Abstract

PURPOSE:To obtain a phenol resin compsn. excellent in heat stability in the plasticized and molten state and in curability at high temp. CONSTITUTION:This phenol resin compsn. contains a phenol resin, microcapsules contg. an alkaline earth metal oxide or hydroxide and having shells with an m.p. of 60-160 deg.C and a viscosity at 160 deg.C of 100P or lower, and microcapsules contg. hexamethylenetetramine and having shells with an m.p. of 60-160 1 and a viscosity at 160 deg.C of 100P or lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phenol resin composition having excellent heat stability and curability, and particularly in the injection molding of a phenol resin molding material, the curing reaction hardly progresses in the cylinder of the injection molding machine. The present invention also relates to a phenol resin composition capable of providing a phenol resin molding material having extremely excellent moldability such that it is rapidly cured in a mold.

[0002]

2. Description of the Related Art Phenolic resin molding materials are representative of phenolic resin compositions. Phenolic resin molding materials are used in a wide range of fields such as automobile parts, electronic / electrical parts, and mechanical parts because of their excellent heat resistance, electric performance, and mechanical properties. However, the conventional phenol resin molding material has a property that, in the molten state plasticized at 90 to 130 ° C., the viscosity increases due to the progress of the curing reaction of the resin in the material, and the fluidity is lost in 5 to 30 minutes. Therefore, the thermal stability of the plasticized molten resin is extremely low. Therefore, when injecting a conventional phenol resin molding material, there is a problem that the plasticizing and melting molding material in the cylinder of the injection molding machine has poor thermal stability and the appropriate molding conditions are extremely narrow. Heretofore, various methods such as increasing the fluidity of the molding material have been known as a method for solving this problem. However, when the thermal stability in the plasticized and molten state is improved, it is
The curing reaction at 60 to 200 ° C. slows down, and on the other hand, when the curability in the mold is improved, the thermal stability becomes poor, and the thermal stability in the plasticized and molten state and the curability in the mold are reduced. At the same time, it was difficult to obtain a phenolic resin molding material having both properties.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made as a result of various investigations for obtaining a phenol resin composition having both thermal stability and curability. For molding materials, phenol resin molding materials that have excellent thermal stability in the plasticized and molten state in the cylinder during injection molding and excellent curability in the mold, and sprue / runnerless injection molding It is a suitable phenolic resin molding material.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to (a) a phenolic resin, (b) an alkaline earth having a wall material made of a compound having a melting point of 60 to 160 ° C. and a viscosity at 160 ° C. of 100 poise or less. Contains metal oxide or hydroxide microcapsules, and (c) hexamethylenetetramine microcapsules having a wall material of a compound having a melting point of 60 to 160 ° C. and a viscosity at 160 ° C. of 100 poise or less. It is a phenol resin composition characterized by being. In the present invention, as the phenol resin (a), a normal novolac type phenol resin or a resol type phenol resin obtained by the reaction of phenol and formaldehyde is used. Examples of phenols of the phenol resin include phenol, cresol, xylenol, naphthol, pt
Examples include monohydric or polyhydric phenols such as butylphenol, bisphenol A, bisphenol F, biphenol, and resorcin, or one or more of substituted compounds thereof. As formaldehydes,
Examples include formalin and paraformaldehyde. Further, as the phenol resin of the present invention, those modified appropriately with aromatic hydrocarbon resin, dimethoxyparaxylene, dicyclopentadiene and the like can be used.

The component (b) of the present invention has a melting point of 60 to
Microcapsules of oxides or hydroxides of alkaline earth metals having a wall material of a compound having a viscosity of 160 poise and a poise of 100 poise or less at 160 deg. Hardly dissolved, 60 ~
It is a microcapsule of an oxide or hydroxide of an alkaline earth metal encapsulated by a wall material that melts at 160 ° C. and becomes a fluid state. Examples of the alkaline earth metal oxides or hydroxides include calcium hydroxide, magnesium hydroxide, barium hydroxide, calcium oxide, magnesium oxide, barium oxide, etc., and usually 100 parts by weight of phenol resin. 1 to 20 parts by weight, preferably 1 to 10 parts by weight are used. The microcapsules are usually spherical or flake-shaped having a particle size of 0.5 to 100 μm, and one or two of them may be used.
More than one species can be used. Next, a hexamethylenetetramine microcapsule having a compound wall material having a melting point of 60 to 160 ° C. and a viscosity at 160 ° C. of 100 poise or less, which is the component (c) of the present invention, is 60 ° C. or less. Is a hexamethylenetetramine microcapsule encapsulated with a wall material that is strong and hardly dissolves in a phenol resin, and melts at 60 to 160 ° C. to be in a fluid state. As hexamethylenetetramine,
Hexamethylenetetramine in powder form, which is used as an ordinary phenol resin curing agent, is used. The microcapsules are usually spherical or flake-shaped having a particle size of 0.5 to 500 μm, and one or two of them are used.
It is possible to use more than one kind.

The wall material of the microcapsules has a melting point of 60-.
160 ° C., preferably 90 to 150 ° C., more preferably 100 to 130 ° C. as a molding material, 160
A compound having a melt viscosity of 100 poise or less, preferably 10 poise or less, for example, low molecular weight polyethylene, low molecular weight polypropylene, low molecular weight polyamide, fatty acid amide, fatty acid ester, metal soap, paraffin, higher fatty acid, hydroxy fatty acid. And the like. The melting point of the wall material of the microcapsule is 60 to 1
Even at 60 ° C., if the melt viscosity at 160 ° C. is 100 poises or more, even if the wall material is melted, the melt has a high viscosity and thus functions as a barrier, and the curing reaction at 160 to 200 ° C. No effect is exerted.

The melting point of the present invention is 60 to 160.
Microcapsules of an oxide or hydroxide of an alkaline earth metal and hexamethylenetetramine having a wall material of a compound having a viscosity of 100 poise or less at 160 ° C at 160 ° C can be prepared as follows. . A compound having the property of melting when heated and solidifying when cooled, as exemplified above, is used as a wall material, and this wall material is dispersed in a solvent that is difficult to dissolve or emulsify at room temperature, and the wall material is heated. To form a solution or emulsion. It is prepared by dispersing therein an alkaline earth metal oxide or hydroxide or hexamethylenetetramine, which is a fine powder of the core substance, and then cooling and depositing the wall material around the core substance. It

Specifically, for example, microcapsules containing calcium hydroxide as a core substance and low molecular weight polyethylene as a wall material are prepared by dissolving low molecular weight polyethylene in heated benzene and adding fine powdery calcium hydroxide thereto. Disperse,
By cooling, the low molecular weight polyethylene is deposited on the surface of calcium hydroxide powder, and then filtered, washed,
It can be obtained by drying. The microcapsules thus obtained have a thermostability in a plasticized molten state of about 90 to 125 ° C. when made into a phenol resin composition even if the core substance is not completely coated with the wall material. It is possible to use as long as it has excellent properties and excellent curability at 160 to 200 ° C., and is included in the scope of the present invention.

In the present invention, 1 to 20 parts by weight of the alkaline earth metal oxide or hydroxide microcapsules are mixed with 100 parts by weight of the phenol resin. If the blending amount is 1 part by weight or less, curing of the resin is insufficient, and if it is 20 parts by weight or more, the appearance and physical properties of the cured product deteriorate. Hexamethylenetetramine microcapsules are 5 parts per 100 parts by weight of phenol resin.
It is used by blending up to 30 parts by weight. If the blending amount is 5 parts by weight or less, the curing of the resin will be insufficient, and if it is 30 parts by weight or more, the physical properties and mechanical properties of the cured product will deteriorate. Further, depending on the case, 5 parts by weight or less of a usual alkaline earth metal oxide or hydroxide and 20 parts by weight or less of a usual hexamethylene tetramine can be used together. In the present invention, if necessary, additives such as a filler, a flame retardant, a colorant, and a release agent can be appropriately mixed and used.

[0010]

The phenol resin composition of the present invention is, for example,
In the molten state at 90 to 125 ° C, the thermal stability is remarkably excellent, and at 160 to 200 ° C, the curability is excellent. The reason for this is not fully clear, but in the case of alkaline earth metal oxide microcapsules, it is 90-125.
In the molten state at ℃, the wall material of the microcapsule blocks the contact between the phenol resin and the alkaline earth metal to prevent the accelerating effect on the curing reaction, but at 160 ° C or higher, the wall material melts and disintegrates and has an extremely low viscosity. It is considered that this is because the physical shielding property of the oxide or hydroxide of the alkaline earth metal disappears, and it acts on the reaction between the phenol resin and hexamethylenetetramine to accelerate the curing reaction. Similarly, in the case of hexamethylenetetramine, 90-
In the molten state at 125 ° C, the wall material of the microcapsules blocks the contact between the phenol resin and hexamethylenetetramine to hinder the curing reaction, but at 160 ° C or higher, the wall material melts and collapses and becomes extremely low in viscosity. It is considered that the physical shielding property of hexamethylenetetramine disappears, the reaction between the phenol resin and hexamethylenetetramine occurs, and it acts as a curing agent. Therefore, when the phenol resin composition of the present invention is applied to a molding material, it has excellent thermal stability in the cylinder of an injection molding machine and excellent curability in a mold.

[0011]

The present invention will be described with reference to the following examples. Here, "parts" represent parts by weight. [Example 1] 45 parts of a novolak resin (average molecular weight 800) obtained by carrying out a reflux reaction of phenol and formaldehyde with an oxalic acid catalyst and 30 parts of low-molecular polyethylene (molecular weight 1000) were dissolved in benzene heated to 70 ° C. Then, 100 parts of finely powdered calcium hydroxide was dispersed therein, cooled, filtered, and dried to obtain 5 parts of microcapsules, low molecular weight polyethylene (molecular weight 1000) 30.
Parts were dissolved in heptane heated to 70 ° C., 100 parts of hexamethylenetetramine in the form of fine powder were dispersed therein, cooled, then filtered and dried to obtain microcapsules 10.
Part, 30 parts of wood flour, 8 parts of calcium carbonate, and 2 parts of a release agent were mixed, melt-mixed with a two-roll mill, cooled and pulverized to obtain a phenol resin molding material.

[Example 2] Phenol resin molding was carried out in the same manner as in Example 1 except that 5 parts of magnesium oxide microcapsules were used in place of the calcium hydroxide microcapsules having the low molecular weight polyethylene as a wall material. Got the material.

Comparative Example 1 45 parts of a novolak resin (average molecular weight 800) obtained by refluxing phenol and formaldehyde with an oxalic acid catalyst, 7 parts of hexamethylenetetramine, 3 parts of calcium hydroxide, and 35 of wood flour.
Parts, calcium carbonate 8 parts, and release agent 2 parts were mixed, melt-mixed with a two-roll mill, cooled and pulverized to obtain a phenol resin molding material. Table 1 shows material properties of the phenolic resins obtained in Examples 1 and 2 and Comparative Example 1.

[0016]

[Table 1]

In Table 1, the in-cylinder stability represents the thermal stability of the molding material in the plasticized and molten state. Specifically, when performing injection molding with a mold for molding JIS test pieces (molded product weight: 170 g), the time from the measurement of the molding material into the cylinder whose temperature is controlled at 100 ° C until the start of injection is The residence time in the cylinder is set to 3
The in-cylinder residence time during which injection was possible was defined as the in-cylinder stability by sequentially increasing 0 second, 60 seconds, and 90 seconds. The longer the time, the slower the curing reaction and the better. The curability represents the curing rate of the molding material in the mold. Diameter 50mm, thickness 5
A transfer molding machine having a cavity of mm and a mold kept at 175 ° C.
30 g of a tablet-shaped molding material preheated to 0 ° C. was charged and molded for 20 seconds, then the molded product was taken out and the hardness of the molded product after 10 seconds was determined by the Barcol hardness tester No. It was measured at 935. The higher the hardness, the faster the curing speed and the better the curability. With respect to the filling property, the state of filling into each cavity was judged from the appearance of the molded product in the injection molding using a die (7 pieces) for molding the JIS test piece.

From Table 1, the phenolic resin molding materials of the present invention shown in Examples 1 and 2 are excellent in thermal stability and curability as compared with the conventional phenolic resin molding material of Comparative Example 1. You can see that

[0019]

As can be seen from the above examples, the phenol resin composition of the present invention is excellent in both thermal stability and curability. In the phenol resin molding material which is an example of the application of the present invention, since the thermal stability in the plasticized and molten state and the curability at high temperature are extremely excellent, particularly in the injection molding machine, in the cylinder of the injection molding machine. Since the progress of the curing reaction of the plasticized molten resin is remarkably suppressed and the resin is rapidly cured in the mold, it can be applied to a wide range of molding conditions and has excellent molding processability. Further, this phenol resin molding material is extremely suitable for sprue / runnerless molding because it has excellent thermal stability in a plasticized and molten state. In addition to the molding material, the phenol resin composition of the present invention can be used in various applications that require excellent thermal stability and curability.

Claims (1)

[Claims] 1. A phenolic resin (a) and a melting point (b) of 60.
To 160 ° C., microcapsules of an alkaline earth metal oxide or hydroxide having a compound wall material whose viscosity at 160 ° C. is 100 poise or less, and (c) a melting point of 60 to
A phenol resin composition comprising: hexamethylenetetramine microcapsules having a compound wall material having a viscosity at 160 ° C of 100 poise or less at 160 ° C.