JPH06116369A - Production of phenolic aralkyl resin - Google Patents

Abstract

PURPOSE:To obtain the subject resin, capable of providing cured products good in electrical characteristics, heat, chemical and abrasion resistances and useful as molding materials, etc., by reacting a specific phenolic compound with an aralkyl ether in the presence of zinc chloride and oxalic acid as a catalyst. CONSTITUTION:A reactor equipped with a condenser through which cooling water at 70 deg.C is passed is charged with an aqueous solution of chloride containing a phenolic compound expressed by formula I (R<1> and R<2> are H, alkyl, phenyl or halogen) (e.g. phenol), an alalkyl ether expressed by formula II [R<3> is 1-6C alkyl; (x) and (y) are integers of 1 or 2; (x+y)=3] (e.g. alpha,alpha'- dimethoxy-p-xylene.), methanol and the zinc chloride. The aqueous solution is then heated while being stirred and an aqueous solution of oxalic acid is then added thereto when the reactional solution temperature attains 140 deg.C. The resultant reactional mixture solution is subsequently made to react for 2.5hr and the methanol and unreacted substances are then removed to afford the objective resin, having a high curing rate when cured with hexamethylenetetramine and good in moldability, electrical characteristics, heat, chemical and abrasion resistances.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fast curing phenol aralkyl resin. The phenol aralkyl resin of the present invention is excellent in electrical characteristics, heat resistance, chemical resistance, wear resistance and the like, and is useful as a base material for molding materials, friction materials and the like.

[0002]

2. Description of the Related Art Conventionally, many methods are known for producing a phenol aralkyl resin which is a reaction product of a phenolic compound and an aralkyl compound. Regarding this production catalyst, for example, JP-B-47-15111 discloses a method using stannic chloride, zinc chloride and ferric chloride, and JP-B-48-10960 discloses a Friedel Crafts containing zinc chloride. A method for obtaining a phenol aralkyl resin using a type catalyst and a diethyl sulfuric acid catalyst is disclosed.

A so-called high ortho phenolic resin (novolak resin) having a large number of ortho bonds, which is obtained by using zinc chloride, has a high reactivity with hexamethylenetetramine (hereinafter abbreviated as HMTA) and is known as a fast hardening resin. .

[0004]

However, these Japanese Examined Patent Publication Nos. 47-15111 and 48-1096.
Since the zinc chloride catalyst disclosed in JP-A-0 has a low activity, a resin cannot be obtained by an ordinary method in the production of a phenol aralkyl resin. The phenol aralkyl resin obtained with a highly active catalyst such as diethylsulfate is
Compared with ordinary phenolic resin (novolac resin), this resin has excellent electrical properties, chemical resistance, abrasion resistance, and heat resistance, but when cured with HMTA, the curing speed is slow and molding There is a drawback that it is inferior in sex, and its improvement has been demanded.

An object of the present invention is to provide a method for producing a phenol aralkyl resin which has a fast curing reaction when cured with HMTA and has good moldability.

[0006]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors have found that the object can be achieved by using zinc chloride and oxalic acid together as a catalyst, and arrived at the present invention. It was

That is, the present invention provides the following general formula (1)

[0008]

[Chemical 3] (In the above formula, R ¹ and R ² represent a hydrogen atom, an alkyl group, a phenyl group or a halogen atom, and may be the same or different.)
And a phenolic compound represented by the following general formula (2)

[0009]

[Chemical 4] (In the above formula, R ³ represents an alkyl group having 1 to 6 carbon atoms,
x and y are integers of 1 or 2 and x + y = 3. ) The aralkyl ether represented by the formula (1) is reacted to produce a phenol aralkyl resin, and zinc chloride and oxalic acid are used together as a catalyst in the process for producing the phenol aralkyl resin.

The present invention will be described in detail below.

The phenolic compound used in the present invention is
General formula (1) [Chemical formula 5]

[0012]

[Chemical 5] (In the above formula, R ¹ and R ² represent a hydrogen atom, an alkyl group, a phenyl group or a halogen atom, and may be the same or different.)
And contains one hydroxyl group bonded to the aromatic nucleus.
Specifically, it is an aromatic compound having a total of 3 or less substituents bonded to carbon atoms of an aromatic nucleus, or a mixture thereof, and phenol, o-cresol, m-cresol, p
-Cresol, 2,6-xylenol, p-tert-
Butylphenol, p-phenylphenol, etc. are mentioned. Particularly preferred phenolic compounds are phenol, o-cresol, p-cresol and the like.

The aralkyl ether used in the present invention is
General formula (2) [Chemical formula 6]

[0014]

[Chemical 6] (In the above formula, R ³ represents an alkyl group having 1 to 6 carbon atoms,
x and y are integers of 1 or 2 and x + y = 3. ), Specifically, α, α′-dimethoxy-p
-Xylene (hereinafter abbreviated as PXDM), α, α'-diethoxy-p-xylene, α, α'-dimethoxy-o-
Xylene, α, α-dimethoxy-m-xylene, α,
α, α'-trimethoxy-p-xylene and the like,
A particularly preferred aralkyl ether is PXDM.

The ratio of the phenolic compound to the aralkyl ether used can be varied over a wide range depending on the molecular weight of the desired resin or the intended use, but the final molar ratio of the reaction system is preferably 1.3 or more. If it is less than 1.3, gelation may occur. Zinc chloride, which is the main catalyst, may be industrial or reagent. The range of use is based on the weight sum of the phenolic compound and the aralkyl ether.
It is preferable to use 0.01% by weight or more, and 0.1 to 0.
5% by weight is more preferable. If it is less than 0.01% by weight, the reaction becomes extremely slow, the resulting resin has poor reactivity with hexamine, and a resin which cures quickly cannot be obtained.

On the other hand, oxalic acid, which is the main catalyst, can be used either as an industrial product or as a reagent, and the amount used is not particularly limited,
It is preferably 0.2 to 1.1 times the moles of zinc chloride used. The shape of the catalyst to be added may be solid, but an aqueous solution is easier to handle. Regarding the method of addition, it is preferable to use a small amount of the catalyst effectively and to add it in portions or continuously in order to obtain a stable reaction and resin. When added all at once, a violent reaction occurs temporarily,
It becomes impossible to control the reaction conditions, and oxalic acid undergoes thermal decomposition and cannot maintain the catalytic effect for a long time.

As a component other than the above-mentioned main raw material, in order to suppress the accumulation of reaction heat at the initial stage of the reaction, in batch or continuous reaction, an amount of methanol (hereinafter abbreviated as spread methanol) which reaches saturation under the reaction conditions is used. It is preferable to charge before the reaction starts. It is also preferable to use an alcohol other than methanol, which is a by-product of the reaction of the phenolic compound and the aralkyl ether, and the same type of alcohol.

As an example of the production method of the present invention, a phenolic compound, aralkyl ether, spread methanol and zinc chloride are charged into a reactor and heated to a reaction temperature to intermittently or continuously add oxalic acid. From the mixture of the alcohol and the phenolic compound and the aralkyl ether to be distilled off, the reaction was continued while the phenolic compound and the aralkyl ether were condensed, and further the aging reaction was carried out until the distillation of the by-product alcohol disappeared. Then, the unreacted phenolic compound is removed under reduced pressure to obtain a phenol aralkyl resin.

The reaction temperature is usually in the range of 120 to 200 ° C, preferably 130 to 160 ° C. 12
If the temperature is lower than 0 ° C, the reaction becomes extremely slow, and if the temperature exceeds 200 ° C, it becomes difficult to condense alcohol by-produced in the reaction.

Further, the partial condensation temperature is from the boiling point of the by-product alcohol to
The temperature is in the range of 150 ° C, preferably 65 to 100 ° C. If the boiling point of the by-produced alcohol is lower than the boiling point of the by-produced alcohol, the by-produced alcohol accumulates, which lowers the reaction temperature and prolongs the reaction. When the temperature exceeds 150 ° C, alcohol containing a high concentration of phenol compound is extracted, which affects the molar ratio of the reaction system.

The reaction may be carried out under pressure or atmospheric pressure, but atmospheric pressure or slight pressurization of 1000 mmH ₂ O or less is preferred. It becomes difficult to stabilize the reaction conditions in the reaction under significantly increased pressure.

Since hydrochloric acid is generated by the combined use of a catalyst, it is preferable to use glass or other non-corrosive materials for manufacturing equipment such as a reactor and a condenser.

[0023]

The present invention will be described in more detail with reference to the following examples. Example 1 229.0 g (2.433 mol) of phenol, 30
2.6 containing 0 g (1.805 mol) of PXDM and 8.0 g of methanol and 0.976 g of zinc chloride.
36 g of zinc chloride aqueous solution was charged into a reactor equipped with a condenser through which cooling water at 70 ° C. was passed, and the temperature was raised in an oil bath while stirring. When the liquid temperature reached 140 ° C, 0.2
After adding 1.054 g of an oxalic acid aqueous solution containing 54 g of oxalic acid to the reactor and conducting the reaction for 2.5 hours,
The same amount of oxalic acid aqueous solution as the first time was added. Furthermore, 1.
After reacting for 5 hours, the same amount of oxalic acid aqueous solution as in the first reaction was added, and the temperature was raised to 150 ° C., and the reaction was continued for 3 hours until the distillation of methanol disappeared. Next, the liquid temperature was raised to 160 ° C. and unreacted phenol was removed under reduced pressure to obtain 400.2 g of a slightly cloudy resin having a softening point of 94 ° C. This is designated as Compound A.

Example 2 158.59 g (1.685 mol) of phenol and 2
Reactor equipped with a condenser in which 00 g (1.203 mol) of PXDM and 3.076 g of an aqueous zinc chloride solution containing 4.76 g of methanol and 1.076 g of zinc chloride were passed through cooling water at 70 ° C. The mixture was charged into and heated with an oil bath while stirring. When the liquid temperature reaches 140 ° C,
10.906 g of an aqueous solution containing 0.906 g of oxalic acid was continuously added over 2 hours and 20 minutes. Then
After raising the liquid temperature to 150 ° C., aging was carried out for 3 hours to complete the reaction. Next, the liquid temperature was raised to 160 ° C., unreacted phenol was removed under reduced pressure, and the slightly softened softening point 93.
248.5 g of resin at 5 ° C. was obtained. This is designated as Compound B.

Example 3 634.44 g (6.741 mol) of phenol and 1
15.511 g of zinc chloride aqueous solution containing 9.0 g of methanol and 5.511 g of zinc chloride was charged into a reactor equipped with a condenser through which cooling water of 70 ° C. was passed, and stirred in an oil bath. The temperature was raised. When the liquid temperature reached 145 ° C, 800.0 g (4.813 mol) of PXDM
And 55.101 g of oxalic acid aqueous solution containing 5.101 g of oxalic acid were continuously added simultaneously over 3 hours. Next, the liquid temperature was raised to 155 ° C. and aging was carried out for 2 hours to complete the reaction. Then, raise the liquid temperature to 160 ° C.,
Unreacted phenol was removed under reduced pressure to obtain 1050.5 g of a slightly cloudy resin having a softening point of 93.0 ° C. This is designated as Compound C.

Example 4 634.19 g (6.739 mol) of phenol and 1
An aqueous solution of 15.495 g of zinc chloride containing 9.03 g of methanol and 5.495 g of zinc chloride was added at 70 ° C.
It was charged into a reactor equipped with a condenser through which the cooling water of (1) was passed, and the temperature was raised in an oil bath while stirring. When the liquid temperature reached 145 ° C, 800.0 g (4.813 mol) of PXD
M was added continuously over 3 hours. 1.01 in parallel
11.013 g of oxalic acid aqueous solution containing 3 g of oxalic acid was divided into 13 portions and added every 30 minutes, that is, over 6 hours. Then, the liquid temperature was raised to 155 ° C. and aging was carried out for 2 hours and 20 minutes to complete the reaction. Then set the liquid temperature to 1
The temperature was raised to 60 ° C., unreacted phenol was removed under reduced pressure, and a slightly cloudy resin 1029.
6 g was obtained. This is designated as Compound D.

Example 5 229.0 g (2.433 mol) of phenol, 30
0 g (1.805 mol) of PXDM, 8.0 g of methanol and 0.976 g of zinc chloride were charged into a reactor equipped with a condenser through which cooling water at 70 ° C. was added, and an oil bath was added while stirring. The temperature was raised. When the liquid temperature reached 140 ° C, 1.255 g containing 0.255 g of oxalic acid
Of oxalic acid in water was added to the reactor. After reacting for 1 hour, the same amount of oxalic acid aqueous solution as the first time was added. Furthermore, after reacting for 1 hour, the same amount of oxalic acid aqueous solution as the first time was added, the temperature was raised to 155 ° C., and the reaction was continued for 3 hours until the distillation of methanol disappeared. Next, raise the liquid temperature to 16
The temperature was raised to 0 ° C., unreacted phenol was removed under reduced pressure, and a slightly cloudy resin 398.2 having a softening point of 92.5 ° C.
g was obtained. This is designated as Compound E.

Comparative Example 1 229.0 g (2.433 mol) of phenol and 30
Charge 0 g (1.805 mol) of PXDM, 8.0 g of methanol and 0.261 g of zinc chloride into a reactor equipped with a condenser passing through cooling water at 70 ° C., and stir in an oil bath. The temperature was raised. When the liquid temperature reached 150 ° C, the mixture was stirred for 1 hour, but there was no distillate. Then 0.2
51 g of zinc chloride was added and the mixture was stirred for 1 hour, but there was no distillate. Add 0.510 g of zinc chloride and add 2
There was no distillate after stirring for hours. Finally, 0.510
g zinc chloride was added, the temperature was raised to 160 ° C. and the mixture was stirred for 2 hours, but there was no distillate. When the reaction liquid was analyzed by gas chromatography, a large amount of phenol and PXDM were detected, and the reaction was substantially not performed.

Comparative Example 2 229.0 g (2.433 mol) of phenol and 30
Charge 0 g (1.805 mol) of PXDM, 8.0 g of methanol and 0.530 g of oxalic acid into a reactor equipped with a condenser through which cooling water at 70 ° C. was charged, and with stirring in an oil bath. The temperature was raised. When the liquid temperature reached 140 ° C., the mixture was stirred for 1 hour, but there was no distillate. Then 0.5
An additional 30 g of oxalic acid was added and stirred for 1 hour, but there was no distillate. Add 0.530g of oxalic acid to add 2
There was no distillate after stirring for hours. When the reaction liquid was analyzed by gas chromatography, a large amount of phenol, PX
DM was detected with virtually no reaction.

Comparative Example 3 229.0 g (2.433 mol) of phenol;
0 g of methanol and 0.536 g of diethyl sulfuric acid were charged into a reactor equipped with a condenser through which cooling water at 70 ° C was passed, and the temperature was raised in an oil bath while stirring. Liquid temperature is 140
When the temperature reached ℃, 300 g (1.805 mol) of P
XDM was added continuously over 3 hours. After the addition is complete
The maturing reaction was performed for 1.5 hours. Then, the liquid temperature was raised to 160 ° C. and unreacted phenol was removed under reduced pressure to obtain 377.5 g of a resin having a softening point of 93.5 ° C. This is designated as Compound F.

Comparative Example 4 470.5 g (4.999 mol) of phenol;
0 g of methanol and 1.046 g of diethylsulfate, 5
740 g of resin having a softening point of 93.0 ° C. in the same manner as in Comparative Example 3 except that 90 g (3.550 mol) of PXDM was used.
Got This is designated as Compound G.

The zinc chloride used in Examples and Comparative Examples was a reagent first-grade product (purity: 91% or more), and oxalic acid was a reagent special-grade product (purity: 99.5% or more, dihydrate).

Measurement of softening point The measuring method is according to JIS K2207.

Measurement of Curing Time For 100 parts by weight of each of the resins A, B, C, D and E obtained in Examples 1 to 5 and the resins F and G obtained in Comparative Examples 3 to 4, 12 parts by weight of HMTA was used. Part, and pulverized with a pulverizer, 0.5 g of which was used, Imanaka Machinery Co., Ltd.
170 ° C using a JRS type curlastometer manufactured by
The time required to reach the maximum torque was measured. The results are shown in [Table 1].

[0035]

[Table 1]

[0036]

INDUSTRIAL APPLICABILITY The phenol aralkyl resin of the present invention is a resin having a significantly improved curing reaction with hexamethylenetetramine as compared with the conventional phenol aralkyl resin. Furthermore, since a weak catalyst is used, even if a trace amount remains in the resin, the thermal stability is high, and it is a production method that can be expected to have features such as less kettle residue generated during production.

Claims (2)

[Claims] 1. The following general formula (1) [Chemical formula 1] (In the above formula, R ¹ and R ² represent a hydrogen atom, an alkyl group, a phenyl group or a halogen atom, and may be the same or different.)
And a phenolic compound represented by the following general formula (2) [Chemical Formula 2] (In the above formula, R ³ represents an alkyl group having 1 to 6 carbon atoms,
x and y are integers of 1 or 2 and x + y = 3. ) The method for producing a phenol aralkyl resin, characterized by using zinc chloride and oxalic acid as a catalyst together when a phenol aralkyl resin is produced by reacting the aralkyl ether represented by the formula (1). 2. The method for producing a phenol aralkyl resin according to claim 1, which is carried out in the presence of alcohol.