JPS63314206A - Polymerization catalyst - Google Patents

Abstract

PURPOSE:To obtain a catalyst which comprises a pyridinium salt of a specified structure and which, by short time heating, can give rise to an active species capable of initiating and proceeding cationic polymn. of an epoxy or vinyl compound rapidly at not so high temperature. CONSTITUTION:The polymn. catalyst comprises a pyridinium salt of formula I, wherein R1 is H or a monovalent aliphatic group selected from among 1-6C alkyl, cycloalkyl, substituted alkyl, and alkoxy groups, R2 is H or an electron attracting substituent, and X<-> is a metal halide. The electron attracting substituent is represented by CN, CF3, NO2 etc., preferably CN.

Description

Detailed Description of the Invention Technical Field The present invention relates to a polymerization catalyst that decomposes upon heating to initiate cationic polymerization and generate active species. That is, it relates to a novel catalyst for cationic polymerization that can be polymerized in a short time at a temperature that is not extremely high.

2. Prior Art In general, catalysts that initiate cationic polymerization have high activity, so polymerization proceeds rapidly even at relatively low temperatures (for a review, see Higashimura, Cationic Polymerization, Kagaku Dojin, 1974).

However, among cationic polymerizations, there have been various problems with the polymerization catalysts used in the polymerization of vinyl compounds such as styrene resins and epoxy resins, which are used in a wide variety of applications such as high-performance materials.

That is, active amine-containing compounds or acid anhydrides that have been widely used as epoxy resin curing agents for two-part systems require thorough mixing of the components of the two-part system using these hardening agents. There is a problem in that the curing time is several hours.

On the other hand, one of the catalysts used as a one-component epoxy resin curing agent that becomes activated by heat is an amino complex catalyst of a Lewis acid such as boron trifluoride and monoethylamine.

When heated, the Lewis acid is depressurized, and the curing time is 1~
Although the curing time is within 8 hours, a curing temperature of 160°C or higher is required, resulting in the problem that these curing agents cannot be used in heat-sensitive devices such as electronic components. . It also has the problem that it cannot be used as a curing agent for epoxy resins with low boiling points. This is because the epoxy resin with a low boiling point evaporates during curing, resulting in loss.

On the other hand, a one-component epoxy resin curing agent that is activated by heat and whose curing temperature is not extremely high is reported by Endo et al. (MakromoLCe+n).

Rapid Commun, 6, 137-139
(1985) or J, Polym, Sci, Po
lym, Lett, Ed.

23.359-363 (1985)) There is a benzyltetrahydrosulfonium salt represented by the following formula (2).

These sulfonium salts do not have a high curing temperature, and are inert to light, but when heat is applied, the sulfonium salts are activated and cure epoxy resins, etc., so they have excellent storage stability at room temperature. However, since the activity is low, it is necessary to use a large amount of catalyst, and it also has the problem that vinyl compounds such as epoxy resins and styrene cannot be cured in a short time. Furthermore, vinyl compounds such as styrene also have the problem that radical polymerization occurs during long-term polymerization reactions.

■Object of the Invention The present invention attempts to solve the problems associated with the prior art as described above. That is, the object of the present invention is to provide a polymerization catalyst used in coating materials, sealing materials, adhesives, matrix resins for composite materials, etc., which initiates cationic polymerization with short heating and generates active species. Another object of the present invention is to provide a catalyst for polymerization of epoxy compounds, vinyl compounds, etc., which allows the polymerization reaction to proceed in a short time at a relatively high temperature, that is, at a temperature that is not extremely high.

■ Structure of the Invention As a result of extensive research into catalysts that can advance polymerization by heating at relatively high temperatures for a short time, the present inventor was able to provide a highly active catalyst by using N-naphthylmethyl-pyridinium salt. The inventors discovered that vinyl compounds and epoxy compounds can be polymerized by short-time heating, and have completed the present invention.

That is, the present invention provides a pyridinium salt tl of the following formula (1) (wherein R1 is one aliphatic group selected from an alkyl group having 1 to 6 H1 carbon atoms, a cycloalkyl group, a substituted alkyl group, and an alkoxy group) , R2 represents H or an electron-withdrawing substituent, and X- represents a metal halide).

In the above invention, a polymerization catalyst in which R is OCH, and R2 is CN%CF and No.
A polymerization catalyst that is any one of 2 is preferred.

The present invention will be explained in detail below.

It is important that the polymerization catalyst of the present invention contains a pyridinium salt having a naphthylmethyl group introduced therein, as shown in the above formula (1). Those in which a benzyl group is introduced instead of a naphthylmethyl group have low activity and do not polymerize quickly. In fact, the formula below (
The pyridinium salt 3) had low activity, and even when 1 g of this pyridinium salt was heated with 99 g of Epibis type epoxy resin at 180° C. for 2 hours, the epoxy resin could not be cured.

In addition, when a similar epoxy resin was heated with a pyridinium salt of formula (4) at 180°C for 2 hours, some of the epoxy reacted and the epoxy resin thickened, but it was not completely cured. I didn't.

On the other hand, when a pyridinium salt of the following formula (5) was used, the epoxy resin could be cured by heat treatment at 100° C. for 5 minutes.

As mentioned above, the reason why high catalytic activity cannot be obtained with the pyridinium salts of formulas (3) and (4) is that the stability of the hensyl cation is low, making it difficult for the C-N bond to dissociate. It seems to have low activity.

On the other hand, in the N-naphthylmethyl-pyridinium salt of formula (5), the cation generated by the dissociation of the C-N bond is more stabilized by the naphthalene ring, so the dissociation of the C-N bond is promoted, resulting in a high It is thought to be an active catalyst.

The naphthylmethyl group contained in the polymerization catalyst of the present invention is unsubstituted, and is also a monovalent aliphatic group selected from alkyl groups having 1 to 6 carbon atoms, cycloalkyl groups, substituted alkyl groups, and alkoxy groups. It may have a group, and specific substituents include CH3, C2I+,, CH3((:H□
)2, ((:O3), (:H1CH3(CH2)3, (
CH3)2cHGHz, CHa(:HzCH((:O3
), C6H, , OCH3, ocH, co3, etc., and OC+13, which has a high electron donating property, is particularly preferred.

Furthermore, in the N-naphthylmethyl-pyridinium salt of the present invention, the pyridine ring preferably has an electron-withdrawing substituent, specifically CN, CF3, NO
2 etc. are exemplified, and CN is particularly preferred.

There may be a plurality of substituents on each of these naphthalene rings and pyridine rings.

Furthermore, the anions in the pyridinium salt of the present invention include:
Metal halides such as 5bF6-1A s F 5-1BF4-1PF6- are preferred.

The polymerization catalyst of the present invention can be widely used as a curing agent for resins having an epoxy group in the molecule, and includes polycondensates of bisphenols and shrimp chlorohydrin, halogenated resins thereof, polyhydric alcohols, It is used for resins in which epoxy groups are introduced by reacting shrimp chlorohydrin with dimer acids, trimer acids, novolacs, etc., resins in which epoxy groups are introduced into polyolefins with peracetic acid, and alicyclic epoxy resins.

The catalyst of the present invention can also be used to polymerize cationically polymerized vinyl compounds such as styrene and vinyl ether (as described in Higashimura, Cationic Polymerization, Kagaku Dojin (1974)).

As a method of using the polymerization catalyst of the present invention, 0.01 to 5 wt% of the above-mentioned epoxy resin or vinyl compound is used.
use Outside this range, the effects of the present invention cannot be obtained sufficiently.

Further, a solvent may be used if necessary. For example, if the catalyst is difficult to dissolve, it is preferable to use it by dissolving it in a polar compound such as phenyl glycidyl ether or acetone.

The polymerization temperature is preferably 60 to 150°C. One of the advantages of the present invention is that it can be polymerized at temperatures that are not extremely high.

■ Examples Hereinafter, the present invention will be specifically explained with examples, but the present invention is not limited thereto (Example 1) This was dissolved and added to 89.5 g of shrimp/bis type epoxy D, E, R, 332 (manufactured by Dow Chemical Japan, epoxy equivalent: 190) to obtain a homogeneous mixture.

When this mixture was heated to 100° C., it gelled within 5 minutes and became glassy. It was completely cured by heating for an additional 30 minutes.

The glass transition temperature of the cured product was 85°C.

Although this mixture was left at room temperature for three months, the viscosity hardly changed, and the IH-NMR spectrum showed that protons based on epoxy groups (5H962,4-4,
2 ppm) remained almost unchanged. It was found that the polymerization catalyst of the present invention also has excellent storage stability.

(Example 2) N-naphthylmethyl-pyridinium salt (Formula 4 % CN, X=As Fe) was blended in the same manner as in Example 1.

The mixture became tack-free within 5 minutes when heated to 100°C.

(Example 3) N-naphthylmethyl-pyridinium salt (formula 4 formula% X=SbF6) was blended in the same manner as in Example 1.

The mixture was heated to 120°C and became tack-free within 30 minutes.

(Example 4) N-naphthylmethyl-pyridinium salt (formula 4% g) was mixed to obtain a homogeneous mixture. This was heated at 100°C.
A viscous liquid was obtained after heat treatment for 5 minutes. When this liquid was dissolved in methyl ethyl ketone and reprecipitated in methanol, a polymer was obtained with a yield of about 85%.
The weight average molecular weight of this polymer was approximately 7,000.

When styrene was treated at 100° C. for 5 minutes as a blank experiment, no methanol-insoluble material was obtained, so radical polymerization did not occur under these reaction conditions. Therefore, when using the catalyst of the present invention, radical polymerization does not occur simultaneously;
It was confirmed that a polymer was produced by cationic polymerization.

(Comparative Example 1) 99.5 g of benzyl-type pyridinium salt (formula (4)) was mixed. This mixture was treated at 150° C. for 1 hour, but no gelation occurred. When the mixture was further heated at 5 o'clock B@, it turned into a gel, but the cured product was extremely brittle.

(Comparative Example 2) Benzyl-type sulfonium salt (X=s in formula (2)
bF6) 0.5g of epoxy D.

E, R, 33299, 5g. This mixture was treated at 120° C. for 10 hours, but no gelation occurred.

(Comparative Example 3) Benzyl-type sulfonium salt (according to formula (2), X=
0.1g of SbFs) was mixed with 1°g of styrene to obtain a homogeneous mixture. Although this was heat-treated at 150° C. for 1 hour, a methanol-insoluble polymer could not be obtained.

(2) Effects of the Invention According to the polymerization catalyst of the present invention, epoxy resins and cationically polymerizable vinyl compounds can be cationically polymerized by heat treatment at a relatively high temperature for a short time, that is, at a temperature that is not extremely high.

At this time, radical polymerization does not occur simultaneously.

This catalyst is stable at room temperature even after mixing with the polymerization composition.
It has excellent storage properties.

Therefore, it is widely used in coating materials, sealing materials, adhesives, matrix resins for composite materials, and the like.

Claims (1)

[Claims] (1) Pyridinium salt of the following formula (1) ▲ Numerical formula, chemical formula, table, etc. are available ▼... (1) (However, R_1 is H, an alkyl group having 1 to 6 carbon atoms,
represents a monovalent aliphatic group selected from a cycloalkyl group, a substituted alkyl group, and an alkoxy group, R_2 represents H or an electron-withdrawing substituent, and X^- represents a metal halide). Characteristic polymerization catalyst.