JP2000273132A - Novolak type phenolic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high molecular weight novolak type phenolic resin excellent in handling, heat-resistant properties, curability and carbonization properties, good in the balance between various properties and suitably usable in a wide range of applications. SOLUTION: A novolak type phenolic resin has an amount of unreacted phenol of not greater than 0.5 wt.% and a weight average molecular weight, based on polystyrene as the reference material, of not smaller than 500,000 and can be obtained by reacting a phenol with paraformaldehyde having a purity of not lower than 85% and/or a polyacetal resin without using a catalyst. Preferably, the weight average molecular weight is not smaller than 1,000,000, and not less than 70% bound methylene groups in the phenolic resin are at the ortho-position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-molecular weight novolak type phenol resin, which has high softening point, heat resistance, and toughness. The present invention relates to a novolak-type phenol resin suitable for a wide range of uses such as carbon products, molding materials, rubber compounds, and epoxy resin curing agents.

[0002]

2. Description of the Related Art Conventionally, novolak type phenol resins are prepared by subjecting phenols and aldehydes, which are called random novolaks, to an addition condensation reaction for several hours at 100 ° C. and normal pressure using a known organic acid and / or inorganic acid as a catalyst. , Obtained by a method of dehydration and removal of unreacted monomers, the type in which the methylene group bonding position is the same as the ortho position and the para position, and phenols and aldehydes are zinc acetate, lead acetate,
After an addition condensation reaction under weak acidity with a metal salt catalyst such as zinc naphthenate, the condensation reaction is carried out directly or further by adding an acid catalyst while dehydration is carried out, and if necessary, an ortho-product obtained by a process of removing unreacted substances is obtained. High orthonovolak having many methylene group bonds at the
No. 0523, JP-A-59-80418 and JP-A-62-230815) are known. However, when a trifunctional phenol is used as the phenol, the weight-average molecular weight of the novolak-type phenol resin obtained by the above-mentioned production method is 1 at the maximum.
There were only about 5,000.

Recently, there has been reported a high orthonovolak (for example, JP-A-6-34583) obtained by reacting a trifunctional phenol and an aldehyde for a long time in a large amount of a non-polar solvent such as xylene. However, the weight-average molecular weight obtained with these resins is 3,000 to
It is about 40,000, which is not a sufficient high molecular weight resin. A method in which a phenol and a formaldehyde source are reacted under pressure to obtain a weight-average molecular weight of 100,000 or more (for example, JP-A-10-298257).
However, there is also a problem that the molecular weight cannot be said to be satisfactory for a wide range of applications and the toughness is insufficient.

[0004] Other high-molecular weight novolak type phenol resins include, for example, those using bifunctional phenols such as orthocresol, paracresol, paranonylphenol, and para-tert-butylphenol as phenols (for example, JP-A-50-136393). JP, JP-A-56-92908, JP-A-56-10321
No. 5, JP-A-57-187311, JP-A-67-17311
A number of reports have been made on the use of bifunctional phenol, but there is a problem that it cannot be completely cured thereafter with a resin using a bifunctional phenol. In recent years, a method of polymerizing phenols by an oxidative coupling reaction using an enzyme such as peroxidase (for example, JP-B-63-5020)
79, JP-A-7-126354),
It is known that a high-molecular-weight phenolic resin can be obtained by this method, but unlike the novolak-type phenolic resin, which is the object of the present invention, it is a very rigid polymer and the establishment of processability and the like is not possible. There is a problem that it is not planned.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to spin phenolic resin fibers, phenolic resinous carbon fibers, etc., phenolic resin films, molding materials for the electric and electronic fields, and curing agents for epoxy resins. Suitable for laminating boards, carbon-based resins, and other wide-ranging applications.Resin alone has sufficient strength, and its cured product is a conventional resin with excellent water resistance, heat resistance, and electrical insulation. It is an object of the present invention to provide a resin that can satisfy all of high molecular weight, high purity, uniform structure, and impart toughness, which have not been simultaneously realized with a novolak type phenol resin.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a high-molecular weight novolak-type phenol resin, which is obtained by reacting a phenol with a paraformaldehyde and / or polyacetal having a purity of 85% or more without using a catalyst. A novolak-type phenol resin characterized in that the phenol content is 0.5% by weight or less and the weight-average molecular weight based on polystyrene as a reference substance is 500,000 or more, preferably the weight-average molecular weight is 1,000. There are more than 2,000. More preferably, the present invention relates to a novolak-type phenol resin in which the methylene bond at the ortho position to the phenolic hydroxyl group is 70% or more of the total methylene bond. It is a resin whose component is 10% by weight or less. If necessary, add 1 part of polyamide resin to novolak type phenol resin.
The present invention relates to a novolak type phenol resin characterized by being modified by 〜50%.

The phenols in the present invention include one or two of compounds having a phenolic hydroxyl group such as phenol, meta-cresol and 3,5-dimethylphenol.
Although at least one species is used, those having no substituent at least except for the meta position with respect to the phenolic hydroxyl group are preferable.
Although there is no problem even if a phenol resin containing an alkyl group or an aryl group having a large number of carbon atoms is used as a substituent, phenol and / or meta-cresol are preferred from the viewpoint of curability, uniform structure and the like. That is, although a phenol having a large substituent has a large molecular weight, the number of nuclei at the same molecular weight is small, leading to a decrease in the hydroxyl equivalent or a large substituent making it difficult to perform three-dimensional curing thereafter. is there.

As an aldehyde source, paraformaldehyde and / or polyacetal resin having a purity of 85% or more is used. Upon reaction with phenol, paraformaldehyde depolymerizes and thermally decomposes the polyacetal resin to formaldehyde. Paraformaldehyde has a purity of 85
% Or more, preferably 90% or more in purity,
More preferably, the purity is 95% or more. If the purity of paraformaldehyde is low and the amount of water is large, there is a high possibility that the polymer is not sufficiently polymerized during the reaction and gelation occurs. As the polyacetal resin, a homopolymer (for example, Tenac 4010 manufactured by Asahi Chemical Industry Co., Ltd.) or a copolymer (for example, Tenac 4520 manufactured by Asahi Chemical Industry Co., Ltd.) is used. The ratio of the phenols to the aldehyde source is not particularly limited, but the molar ratio of the aldehydes to the phenols when converted to formaldehyde is 0.1.
About 6 to 1.2 is preferable.

The molecular weight and bonding mode of the resin of the present invention are characterized by having a weight average molecular weight of 500,000 or more, preferably 1,000,000, using polystyrene as a standard substance.
000 or more, and more preferably 70% or more of all the bonded methylene groups are bonded at the ortho position. In this case, since the highly reactive para position is vacant, for example, if hexamethylenetetramine is added, a cured product can be obtained in a short time by heating or the like. The novolak-type phenolic resin of the present invention is highly ortho-ortho-bonded structurally, and a carbide obtained by carbonizing this is close to a graphite structure, but is not a complete crystal structure. It is possible to obtain a well-balanced property between mechanical properties such as strength and hardness and electrical properties such as conductivity.

In the reaction, phenols are added in an amount of 5 to 2
There is no problem even if the solvent is used in an amount of 00% by weight. In particular, when a non-polar solvent such as toluene or xylene is used, the bond selectivity at the ortho position can be increased. The novolak-type phenolic resin of the present invention has toughness due to its large molecular weight and uniform bonding state, and heat resistance and strength can be obtained by itself.

In applications requiring further toughness, it is preferable to modify the polyamide resin by 1 to 50% by weight based on the novolak type phenol resin, if necessary. As the polyamide resin to be used, nylon 6 (for example, nylon 1013B manufactured by Ube Industries, Ltd.), nylon 66
(For example, Nylon 2020B manufactured by Ube Industries, Ltd.),
Nylon 12 (for example, Nylon 30 manufactured by Ube Industries, Ltd.)
24U) and nylon 610 (for example, Nylon 610 manufactured by Toray Industries, Inc.) are preferable, but there is no problem even if a copolymer type or other polyamide resin is used. The modification ratio of the polyamide resin is preferably from 1 to 50% by weight, more preferably from 5 to 20% by weight, based on the novolak type phenol resin. If the amount is less than 1% by weight, the desired modifying effect cannot be obtained, and if the amount exceeds 50% by weight, heat resistance, curability and burning resistance are adversely affected.

In the resin of the present invention, unreacted phenols are 0.5% or less as a low molecular weight region, preferably 0.1% or less.
1% by weight or less. More preferably, the binuclear component is 3% by weight or less and / or the tetranuclear component or less is 10% by weight or less. If the amount of unreacted phenol is large, odor is generated during processing of the resin, which causes a problem in working environment, and a low molecular weight region may cause deterioration in physical properties depending on the use application.

The method for producing the resin of the present invention is as follows. An aldehyde source composed of phenols and paraformaldehyde having a purity of 85% or more and / or polyacetal resin, and if necessary, a polyamide resin are added.
An addition condensation reaction is performed at 80 to 250 ° C.
It is obtained by advancing a polymerization reaction while dehydrating at 0 ° C., and then dehydrating and removing unreacted phenol, or, if necessary, dissolving this resin in an appropriate solvent and then precipitating. .

[0014]

The present invention will be described below in more detail with reference to examples and comparative examples. However, the present invention is not limited by these examples. It should be noted that all “%” described in the text indicate “% by weight”.

Example 1 22.0 kg of phenol and 5.7 kg of paraformaldehyde having a purity of 92% were put into a 50 L high-pressure reactor equipped with a heat exchanger, a heating device and a stirring blade, and heated to 180 ° C. for addition. A condensation reaction was performed. The reaction liquid rose to 230 ° C. due to self-heating. Further, the reaction was continued for 2 hours while heating to keep the temperature at 220 to 230 ° C., and then the dehydration reaction was performed while returning to normal pressure for 30 minutes via a heat exchanger. After this, 1.3KP
The pressure was reduced to a and the unreacted phenol was removed for 30 minutes.
The solid was taken out on a cooling vat to obtain 20.0 kg of a solid novolak phenol resin. The properties of the obtained resin are shown in Table 1 and gel permeation chromatography (hereinafter, referred to as gel permeation chromatography).
FIG. 1 shows a molecular weight distribution chart measured by GPC).

Example 2 Phenol 24.
Add 0 kg and use polyacetal resin homopolymer as aldehyde (Tenac 4010 manufactured by Asahi Kasei Kogyo Co., Ltd.)
Was obtained in the same manner as in Example 1 except that 6.0 kg of the novolak type phenol resin was used, and that no unreacted phenol was removed under reduced pressure.
The properties of the obtained resin are shown in Table 1, and the molecular weight distribution chart by GPC is shown in FIG.

Example 3 20.0 kg of the novolak type phenol resin obtained in Example 1 was mixed with 20.0 kg of acetone.
g, then add a mixed solution of 30.0 kg of pure water and 70.0 kg of methanol to the solution at a temperature of 30 ° C. over 1 hour. After standing for 1 hour, remove the separated lower layer and remove it with a vacuum dryer for 2 hours. After the treatment, the solvent was removed to obtain 12.5 kg of a solid novolak type phenol resin. The properties of the obtained resin are shown in Table 1, and the molecular weight distribution chart by GPC is shown in FIG.

Example 4 20.0 kg of the novolak type phenol resin obtained in Example 2 was mixed with 20.0 kg of acetone.
g, then add a mixed solution of 10.0 kg of pure water and 90.0 kg of methanol over 1 hour to a liquid temperature of 30 ° C., leave for 1 hour, take out the separated lower layer, and place 2.0 kg of acetone in a dish. Was added and mixed to obtain 25.5 kg of a liquid novolak type phenol resin. The properties of the obtained resin are shown in Table 1, and the molecular weight distribution chart by GPC is shown in FIG.

Example 5 All of Example 1 was used except that 20.0 kg of phenol, 2.0 kg of nylon 12 (Nylon 3024U manufactured by Ube Industries, Ltd.) and 5.4 kg of 88% paraformaldehyde were used as the polyamide resin. Novolak type phenol resin 23.0 in the same manner as
Kg was obtained. Table 1 shows the properties of the obtained resin.
FIG. 5 shows a molecular weight distribution chart according to FIG.

Comparative Example 1 Into the reactor used in Example 1, 22.0 kg of phenol and 0.22 kg of oxalic acid, which is a typical novolak catalyst, were added and heated to 100 ° C. at normal pressure, and then 40% After slowly adding 12.9 kg of formalin over 90 minutes, the reaction was continued for 60 minutes while maintaining 100 ° C. Further, after dehydrating the resin while heating it to 130 ° C. at normal temperature, the pressure was reduced to 1.3 KPa, and unreacted phenol was removed until the reaction solution temperature reached 180 ° C.
It was taken out into a cooling vat to obtain 21.0 kg of a novolak type phenol resin. Table 1 shows the properties of the obtained resin.

<< Comparative Example 2 >> The amount of 40% formalin was changed to 1
A novolak-type phenol resin (23.0 kg) was obtained in the same manner as in Comparative Example 1 except that the amount was 4.7 kg. The properties of the obtained resin are shown in Table 1, and the molecular weight distribution chart by GPC is shown in FIG.

Comparative Example 3 Into the reactor used in Example 1, 22.0 kg of phenol, 4.8 kg of 88% paraformaldehyde and 0.22 kg of zinc acetate, a representative of a divalent metal salt as a high orthonovolacation catalyst, were placed. Then, the mixture was heated to 100 ° C. under normal pressure, kept at 100 ° C., and the reaction was continued for 3 hours. Thereafter, the mixture was cooled to 90 ° C. and mixed with 0.11 kg of oxalic acid and 0.33 kg of water as a condensation reaction promoting catalyst. The mixture was added, mixed for 30 minutes, heated to 100 ° C. again, and reacted for 1 hour. Further, after dehydration at normal pressure to 130 ° C., the pressure was reduced to 1.3 KPa, and the temperature of the reaction solution was 1
Unreacted phenol was removed until the temperature reached 80 ° C., taken out into a cooling vat, and 20.0 kg of a novolak type phenol resin was obtained. Table 1 shows the properties of the obtained resin.
FIG. 7 shows a molecular weight distribution chart based on the above.

Comparative Example 4 A reaction was conducted in the same manner as in Example 1 except that 13.1 kg of 40% formalin was used instead of 92% paraformaldehyde. It gelled at the same time.

Comparative Example 5 A reaction was conducted in the same manner as in Comparative Example 1 except that the amount of formalin was changed to 15.6 kg, and the reaction time at 100 ° C. after the addition was changed to 5 hours. It has become.

[0025]

[Table 1]

Examples 6 to 9 and Comparative Examples 6 to 8 Using the novolak-type phenolic resins obtained in the above Examples and Comparative Examples, molded articles were prepared and their physical properties were compared. The compounding of the materials for obtaining the molded product is as follows: resin 10 parts by weight, Kevlar fiber 5 parts by weight, glass fiber 5 parts by weight, barium sulfate 55 parts by weight, calcium hydroxide 2 parts by weight, cashew dust 3 parts by weight, copper powder 15 The mixture is obtained by mixing 0 to 1.5 parts by weight of hexamethylenetetramine as a curing agent and 0 to 1.5 parts by weight with an Erich mixer for 2 minutes. The molding conditions of the molded article containing the curing agent were as follows: preforming was performed at a room temperature press of 300 kg / cm ² , main molding was performed at 200 ° C. under a hot press of 200 kg / cm ² for 10 minutes, and baking was performed at 200 ° C. and a normal pressure of 5 hours. . The molding conditions of the molded body not containing the curing agent are as follows.
0Kg / cm ² room temperature press, final molding at 250 ° C
0Kg / cm ² heating press for 30 minutes, firing at 200 ° C
At normal pressure for 5 hours. Table 2 shows the obtained results.

[0027]

[Table 2]

<< Examples 10 to 14, Comparative Examples 9 to 12 >>
The novolak-type phenol resin obtained in the above Examples and Comparative Examples was fired in an electric furnace at 800 ° C. for 3 hours in a reducing atmosphere to obtain a carbide. Table 3 shows the blending conditions and the residual carbon ratio. The resin of Example 4 was dried at 125 ° C. for 2 hours in advance to remove the solvent, and then performed. The carbonization rate was determined by the following equation. Residual carbon ratio (%) = weight of carbide / (weight of input resin + weight of curing agent) × 100

[0029]

[Table 3]

(Measurement method) The weight average molecular weight was measured by a gel permeation chromatography (GPC) method using an ultraviolet absorption spectrum detector using polystyrene as a standard substance. For the resin modified with the polyamide resin, the THF-soluble portion was measured. 2. The monomer content was measured by a capillary gas chromatography method. Ortho-position bond rate is ¹³ C-NMR
The methylene group bond amount determined by the spectral method was calculated by substituting into the following equation. Ortho bond ratio = [{(oo bond) + (op bond) /
2} / {(oo-bond) + (op-bond) + (pp-bond)}] × 100 oo-bond: number of ortho-ortho-bond methylene groups op-bond: ortho-para Number of methylene groups bonded at the position pp bond: Number of methylene groups bonded at the para-para position

As is evident from these results, the novolak type phenolic resin obtained in the examples has a very high molecular weight, a high number of ortho-methylene bonds and a low molecular weight such as unreacted phenol. It turns out that it is a thing with few components. In addition, this novolak type phenolic resin is excellent in curing properties and carbonization properties, and can be used sufficiently even without using or reducing a curing agent.Furthermore, due to its structural characteristics, a new resin that has not been obtained with conventional resins It can be seen that characteristics can also be obtained.

[0032]

The novolak-type phenolic resin of the present invention is a high-molecular-weight resin which has not existed conventionally, and is a phenol resin having a small amount of unreacted phenol or low-molecular-weight and highly ortho-bonded. In addition, the cured product is excellent in heat resistance, electrical insulation and moisture resistance, so it can be applied to a wide range of applications including electric and electronic fields. In the field of products and carbon products, various flame retardants and flame retardant assistants, and when used alone, it can be used for fibers and films, and is an industrially useful phenol resin.

[Brief description of the drawings]

FIG. 1 is a molecular weight distribution chart of the resin obtained in Example 1 by GPC.

FIG. 2 is a GPC molecular weight distribution chart of the resin obtained in Example 2.

FIG. 3 is a GPC molecular weight distribution chart of the resin obtained in Example 3.

FIG. 4 is a GPC molecular weight distribution chart of the resin obtained in Example 4.

FIG. 5 is a GPC molecular weight distribution chart of the resin obtained in Example 5.

FIG. 6 is a GPC molecular weight distribution chart of the resin obtained in Comparative Example 2.

FIG. 7 is a GPC molecular weight distribution chart of the resin obtained in Comparative Example 3.

Claims (5)

[Claims] An unreacted phenol obtained by reacting a phenol with a paraformaldehyde and / or a polyacetal resin having a purity of 85% or more without using a catalyst has an unreacted phenol of 0.1%.
A novolak-type phenolic resin having a weight-average molecular weight of not more than 5% by weight and a polystyrene as a reference substance of not less than 500,000. 2. A phenol resin having a weight average molecular weight of 1,
The novolak-type phenolic resin according to claim 1, wherein the phenolic resin is not less than 1,000,000. 3. The novolak-type phenol resin according to claim 1, wherein 70% or more of the positions of the bonding methylene groups of the phenol resin are ortho positions. 4. The novolak-type phenol resin according to claim 1, wherein the binuclear component is 3% by weight or less and / or the tetranuclear component or less is 10% by weight or less. 5. A novolak-type phenol resin according to claim 1, 2, 3 or 4, wherein the polyamide resin is 1 to 5 times.
Novolak type phenol resin modified by 0% by weight.