JPH0753764B2 - Polymerization method of vinyl monomer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel polymerization method for vinyl monomers, which is derived from the research on the elucidation of the polymerization mechanism of the known plasma-initiated polymerization method.

[Prior Art and its Problems] JP-A-54-118483 discloses that a non-vapor phase (liquid or solid) monomer, especially methyl methacrylate, is contacted with an ionized gas plasma of the monomer to initiate polymerization, A plasma-initiated polymerization method is disclosed in which contact with and termination of post-polymerization is carried out.

In this method, the ionized gas plasma of the monomer to be polymerized is brought into contact with the monomer in the non-vapor phase to generate an active polymerization seat at the interface between the plasma and the non-vapor phase monomer phase, thereby The polymerization reaction is excited and then post-polymerized in the absence of plasma, and in that the plasma gas functions as a kind of polymerization initiator only for initiating the polymerization reaction, the series of polymerization reactions is It is a completely different polymerization method from the usual plasma polymerization method performed in the presence.

The present inventors previously disclosed in JP-A-59-62603 that the allyl radical present in the ionized gas plasma in the above plasma-initiated polymerization is deeply involved in the formation of the active polymerization seat in the vinyl monomer for polymerization. In addition, from the elucidation of the mechanism of the plasma-initiated polymerization method, even if it is an ionized gas plasma of a compound different from the vinyl monomer for polymerization, if the plasma contains an allyl radical, the ionized gas plasma It is possible to induce plasma-initiated polymerization by contacting the vinyl monomer for polymerization with the vinyl monomer for polymerization, and it is possible to induce plasma-initiated polymerization of almost any vinyl monomer by appropriately combining the type of vinyl monomer for polymerization and the type of ionized gas plasma. Disclosed.

However, in the above-mentioned conventional technique, the radical species such as allyl radicals generated in the ionized gas plasma maintain their long life even after the supply of the gas polymer is stopped, and continue to function as the polymerization initiation active species. It still remains a big question, and this was one of the major factors that hinder the industrial application of plasma-initiated polymerization.

Therefore, as part of the investigation of the above-mentioned questions, the inventors of the present invention, an organic compound that generates a polymerization initiation active species by plasmaization, a glass carrier treated with a plasma gas of methyl isobutyrate as a spin trapping agent. As a result of measuring the ESR spectrum in the presence, it was clearly shown that the organic radical species existed, and that the organic radical species increased with time.

That is, the plasma-initiated polymerization active radical species generated in the plasma gas of the low molecular weight organic compound are trapped and stabilized in the ultra-thin film formed on the surface of the glass reaction tube, and the radical species are solvent or polymerization vinyl. It has been reported that contact with a monomer causes it to be gradually released from the organic thin film, and initiation of plasma-initiated polymerization and post-polymerization proceed efficiently for a long time (Journal of the Chemical Society of Japan, No. 6, 1985).
1007).

In addition, when the mechanism of the catalyst mechanism of the polymerization initiator exhibited by the ultra-thin film was positively investigated, the mechanism was a dry film formation method peculiar to the plasma reaction in which the film was formed directly from the gas phase on the solid surface. There is a weak chemical bond site with the strain of, the bond breaks due to the action of the solvent, the small pieces of the polymer film elute in the solution, and the bond break continues under the contact with the monomer. It has been proposed that the polymerization is initiated depending on the site.

However, in the polymerization method, the combination selection of the plasma organic gas, the solvent used in the post-polymerization, and the structure of the monomer is the key to the success or failure of the polymerization, and the solvent and the monomer that can be effectively used are necessarily restricted, and the polymerization efficiency is high. Has the drawback of being restricted.

Therefore, the present inventors subject the thin film produced to mechanochemical treatment to impose a mechanochemical factor to increase the number of weak chemical bond sites where bond rupture is easy, and the number of free radical sites increases when regenerated or generated. The inventors have found that the polymerization reaction is promoted and have completed the present invention.

[Means for Solving Problems] That is, according to the present invention, when a glass carrier treated with a non-equilibrium plasma gas of an organic compound is brought into contact with a vinyl monomer for polymerization to initiate polymerization of the vinyl monomer, The present invention provides a method for polymerizing a vinyl monomer, which is characterized in that it is subjected to a chemical treatment.

[Operations and Examples] As the plasma-enhancing compound for generating the non-equilibrium plasma gas used in the present invention, a hydrocarbon radical species which is a plasma-initiated polymerization active radical species in the ionized gas plasma of the plasma-enhancing compound, for example, Compounds that generate unsaturated alkyl radical species such as aryl radicals and vinyl radicals, saturated alkyl radical species, and the like, and include ordinary organic compounds. More specifically, for example, ester compounds such as methyl butyrate, methyl isobutyrate and methyl methacrylate;
Propene tetramers, paraffin hydrocarbons such as n-hexane; olefin hydrocarbons such as 1,5-hexadiene and 4-methyl-1-pentene; 3-hydroxy-3-methim-2-butanone; benzene, styrene, etc. Examples include various organic compounds such as aromatic hydrocarbons, and one kind or two or more kinds thereof are mixed to generate plasma. Among them, a low molecular weight organic compound that is easily turned into plasma is preferable, and further, an unsaturated group-containing organic compound that requires a short plasma discharge time is preferably contained.

Examples of the vinyl monomer for polymerization used in the present invention include ordinary vinyl monomers, and specifically, for example, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, propyl methacrylate, propyl acrylate, butyl methacrylate, butyl acrylate, pentyl. Methacrylic acid or acrylic acid ester such as methacrylate, pentyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate; polymerizable carboxylic acid such as methacrylic acid, acrylic acid; Methacrylamide, acrylamide, dimethylmethacrylamide, dimethylacetate Examples thereof include vinyl monomers such as rilamide, N-vinyl-2-pyrrolidone, styrene, and alkylstyrene. Among them, methacrylate compounds and acrylate compounds having a small polymerization initiation activation energy are preferably used because of their high polymerization progress rate. . The vinyl monomer for polymerization may be used alone or
One or more kinds may be mixed and used, and when two or more kinds are mixed and used, copolymerization of the mixed vinyl monomers is possible.

The glass carrier used in the present invention may be made of a silicon-based inorganic compound, and ordinary inorganic glass, hard glass, heat resistant glass, and quartz glass can efficiently initiate polymerization. For the shape,
Fibre, plate, sheet, cylinder, block, sphere,
It may be a cotton mold or a polymerization mold or container for the above-mentioned vinyl monomer for polymerization capable of molding a desired molded article.

The conditions of the plasma discharge for generating the non-equilibrium plasma gas of the organic compound of the present invention are not limited requirements of the present invention, but usually, in a gas atmosphere of the compound to be plasmaized, the pressure is about 0.001 to 20 Torr, preferably Is 0.01 to 2 Torr, power is about 5 to 200 W, preferably about 10 to 120 W, discharge time is several seconds to
It may be set within a range of several tens of minutes. There is no limit on the frequency, and it is possible from direct current to microwave, for example
It can also be applied using a commercially available plasma generator with a radio frequency of 13.56 MHz. An external or internal balanced electrode plate or a coil-shaped electrode can be used as the electrode.

The mechanochemical treatment used in the present invention is short-time ultrasonic irradiation or non-reactive plasma short-time irradiation, and further,
This is a combination of short-time irradiation of non-reactive plasma and ultrasonic irradiation for a short time, and the ultra-thin film generated by the action of non-equilibrium plasma is destroyed by mechanochemical treatment and trapped and stabilized in the ultra-thin film. It has the effect of liberating the plasma-initiated polymerization active radical species.

As the ultrasonic wave irradiation for a short time, those of 20 to 100 KHz are preferable, and it is sufficient to use a commercially available 27 KHz ultrasonic cleaner because there is an advantage that it can be easily obtained. If it exceeds 100 KHz, it may damage the glass container, which is not preferable. The irradiation time is preferably several to several hundreds of seconds, and preferably 5 to 300.
Seconds are more preferred. Less effective for 5 seconds or less 30
Even if the time is longer than 0 seconds, the effect will not increase.

As the non-reactive plasma, plasma of an inert gas is used, and He, Ar, Ne and the like can be mentioned. The irradiation time may be several to several tens of seconds. Other conditions may be the same as the plasma irradiation conditions.

In a preferred embodiment of the present invention, method (A): (A-1) depressurizing a container for plasma discharge to an appropriate pressure (A-2) introducing a gas of an organic compound into the container (A-3) ) Plasma discharge of a part or all of the container (A-4) After returning the inside of the container to normal pressure, monomers are put therein and the container is depressurized and sealed (A-5) After ultrasonic irradiation for a certain period of time (A- 6) The polymerization is completed by leaving it at a suitable temperature for several to several hundred hours. Method (B): (B-1) The pressure of the plasma discharging container is reduced to a suitable pressure (B-2) In the container Introducing a gas of an organic compound (B-3) plasma-discharging a part or all of the container (B-4) returning the inside of the container to normal pressure, and then depressurizing the inside of the container to an appropriate pressure again (B-4). -5) Inert gas is introduced into the container (B-6) Part of the container or The whole is plasma-discharged (B-7) After the inside of the container is returned to normal pressure, the monomer is put therein and the pressure is reduced and sealed (B-8) The polymerization is completed by leaving it at a suitable temperature for several to several hundred hours. Method (C): (C-1) to (C-7): same as (B-1) to (B-7) (C-8) after ultrasonic wave irradiation for a certain period of time (C-9) number to The polymerization is completed by leaving it at a suitable temperature for several hundred hours.

Further, in the method (C), (C-7) and (C-8), that is, the monomer injection step and the ultrasonic wave irradiation step may be exchanged. This is because the ultrasonic wave affects the thin film formed by the first plasma irradiation.

Especially preferred is method (C).

Also, at the stage of completing the polymerization by leaving it, for example, 20 to 80 ° C.
The polymerization rate can also be increased by supplying energy such as heating to a certain degree or irradiation of ultraviolet rays.
This method is particularly effective when polymerizing a low-polymerizable monomer such as N-vinyl-2-pyrrolidone or styrene.

The polymerization system may be either a gas phase or a liquid phase at the start of the polymerization, but the post-polymerization is usually carried out in the liquid phase. A solvent may be used in the polymerization, but a solvent that dissolves an ultra-thin film generated by plasma irradiation is not preferable, and it varies depending on an organic compound (hereinafter, referred to as an initiator) for generating a non-equilibrium plasma gas to be used. Water can be used as a solvent for most initiators. In addition, methyl isobutyrate is used depending on the initiator.

The present invention will be further described below with reference to examples, but the present invention is not limited to the examples.

Example 1 (Method A) A glass container having an inner volume of 50 ml was depressurized to 0.001 Torr, and benzene (hereinafter referred to as “B” as an organic compound (initiator)).
(abbreviated as “z”) vapor was introduced until the pressure inside the container reached 0.5 Torr, and the container was sealed.

The entire container was subjected to plasma discharge treatment at 50 W for 60 seconds. After sealing the container, add 1.0 g of a 50 wt% aqueous solution of acrylic acid as a vinyl monomer for polymerization (hereinafter, this aqueous solution is referred to as "AA"), and use a dry ice-acetone-based cryogen (hereinafter, DA cryogen). After cooling, the pressure was reduced to 0.001 Torr, the container was sealed, ultrasonic irradiation (27 KHz, 150 W) was applied for 10 minutes, and the mixture was left at 65 ° C. for 30 minutes to carry out post-polymerization. The yield of the obtained polymer was 8.08% and the polymerization reaction rate was 3.12 × 10.
^{It was -4} (M / sec).

Example 2 (Method B) A glass container having an inner volume of 50 ml was depressurized to 0.001 Torr, and Bz vapor as an organic compound (initiator) was introduced and sealed until the pressure in the container became 0.5 Torr.

The entire container was subjected to plasma discharge treatment at 50 W for 60 seconds. After sealing the container, the glass container was again depressurized to 0.001 Torr, and He gas was introduced until the pressure in the container became 0.5 Torr and sealed.

The entire container was subjected to plasma discharge treatment at 50 W for 5 seconds. After sealing the container, 1.0 g of AA was added as a vinyl monomer for polymerization, cooled with a DA cryogen, depressurized to 0.001 Torr and sealed, and left at 65 ° C. for 30 minutes to carry out post-polymerization.

The yield of the obtained polymer was 5.28%, and the polymerization reaction rate was 2.04 × 10 ⁻⁴ (M / · sec).

Example 3 (Method C) A glass container having an inner volume of 50 ml was depressurized to 0.001 Torr, and Bz vapor as an organic compound (initiator) was introduced and sealed until the pressure in the container became 0.5 Torr.

The entire container was subjected to plasma discharge treatment at 50 W for 60 seconds. After sealing the container, the glass container was again depressurized to 0.001 Torr, and He gas was introduced until the pressure in the container reached 0.5 Torr and sealed.

The entire container was subjected to plasma discharge treatment at 50 W for 5 seconds. After sealing the container, add 1.0 g of AA as a vinyl monomer for polymerization, cool with D-A cryogen, reduce the pressure to 0.001 Torr and seal, and subject to ultrasonic irradiation (27 KHz, 150 W) for 10 minutes at 65 ° C.
It was left for 30 minutes to carry out post-polymerization.

The yield of the obtained polymer was 7.62%, and the polymerization reaction rate was 2.94 × 10 ⁻⁴ (M / · sec).

Comparative Example 1 A glass container having an internal volume of 50 ml was depressurized to 0.001 Torr, and Bz vapor as an organic compound (initiator) was introduced until the internal pressure of the container became 0.5 Torr and sealed.

The entire container was subjected to plasma discharge treatment at 50 W for 60 seconds. After sealing the container, 1.0 g of AA as vinyl monomer for polymerization
Was charged, cooled with a DA cryogen, depressurized to 0.001 Torr and sealed, and left at 65 ° C. for 30 minutes for post-polymerization. The yield of the obtained polymer was 4.08%, and the polymerization reaction rate was 1.57.
It was × 10 ^-4 (M / sec).

Examples 4 to 20 Polymers were obtained by the same procedure as in Examples 1 to 3 except that the type of initiator, the type of vinyl monomer for polymerization, the post-polymerization time, and the initial plasma irradiation time were changed. . The results are shown in Table 1.

In addition, "A" is shown in the method column for the same operation as in the first embodiment, "B" in the method column for the same as the second embodiment, and "B" in the method column for the third embodiment. "C" was entered in the method column.

Comparative Examples 2 to 8 Polymers were obtained in the same manner as in Comparative Example 1 except that the type of initiator, the type of vinyl monomer for polymerization, the post-polymerization time, and the plasma irradiation time were changed. The results are shown in Table 1. MIB represents methyl isobutyrate, HD represents 1,5-hexadiene, and St represents styrene.

Example 21 A glass container having an internal volume of 50 ml was depressurized to 0.001 Torr, and vapor of methyl isobutyrate as an organic compound (initiator) was introduced until the pressure in the container became 0.5 Torr and sealed.
The entire container was subjected to plasma discharge treatment at 50 W for 60 seconds. After opening the container, the glass container was again depressurized to 0.001 Torr, He gas was introduced until the pressure in the container became 0.5 Torr, and the container was sealed.

The entire container was subjected to plasma discharge treatment at 50 W for 5 seconds, and further subjected to ultrasonic treatment at 27 KHz and 150 W for 10 minutes. After opening the container, 0.5 g of methyl methacrylate was added as a vinyl monomer for polymerization and post-polymerization was carried out at 65 ° C. for 22 hours.

Yield 9.98%, polymerization reaction rate 1.19 × 10 ^-5 (M /
It was c).

Claims (1)

[Claims] 1. Polymerization of a vinyl monomer for polymerization by contacting a glass carrier treated with a non-equilibrium plasma gas of a plasmatized organic compound that generates a plasma-initiated polymerization active radical species in an ionized gas plasma with a vinyl monomer for polymerization. A method for polymerizing vinyl monomers, characterized in that a mechanochemical treatment is applied when starting.