JPH0667986B2 - Method for producing aromatic vinyl-based copolymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an aromatic vinyl copolymer excellent in heat resistance and coloring resistance.

(Problems to be Solved by Prior Art and Invention) As a thermoplastic resin having excellent heat resistance, a ternary copolymer of α-methylstyrene, acrylonitrile and maleimide is known. For example, in JP-A-61-296011, an aromatic vinyl monomer represented by α-methylstyrene, a vinyl cyanide monomer represented by acrylonitrile, and a maleimide-based monomer represented by a specific general formula are disclosed. Polymerization of a mixture of monomers, the polymerization conversion of maleimide monomer is 80%
At the above steps, a method of adding an aromatic vinyl monomer and a vinyl cyanide monomer to complete the polymerization is shown.
According to this method, it is possible to obtain a terpolymer that is excellent in heat resistance and that prevents yellowing due to molding to some extent. However, such a coloring resistance is not yet sufficient, and the advent of a heat-resistant thermoplastic resin having more excellent coloring resistance has been desired.

(Means for Solving the Problem) The present invention aims to develop a heat-resistant thermoplastic resin capable of almost completely preventing yellowing due to the above-mentioned molding,
As a result of continuing diligent research, they succeeded in achieving the above object and completed the present invention.

That is, the present invention is a polymerization yield of a mixture of an aromatic vinyl-based monomer, an unsaturated nitrile-based monomer and an unsaturated dicarboxylic acid imide-based monomer in an aqueous medium in the presence of an oil-soluble polymerization initiator.
Polymerization until reaching 80% by weight or more, and then radical polymerization is added to carry out the polymerization in the presence of a water-soluble polymerization initiator to produce an aromatic vinyl copolymer. Is the way.

As the aromatic vinyl-based monomer that can be used in the present invention, known monomers can be used as long as they are monomers having both a vinyl group and an aromatic ring group. For example, if typical ones of aromatic vinyl-based monomers are shown, styrene, α-methylstyrene,
Examples thereof include styrene such as P-methylstyrene and P-chlorostyrene or derivatives thereof. Considering the heat resistance of the resulting aromatic vinyl-based copolymer, α-methylstyrene is preferably used.

Next, as the unsaturated nitrile-based monomer, a known monomer having a vinyl group and a cyano group is used without particular limitation.
Specifically showing such an unsaturated nitrile monomer,
Examples thereof include acrylonitrile and methacrylonitrile.

Next, as the unsaturated dicarboxylic acid imide-based monomer, a known monomer obtained by reacting an unsaturated dicarboxylic acid with an amine is used without any limitation. Specific examples of the unsaturated dicarboxylic acid imide-based monomer preferably used in the present invention include N-phenylmaleimide and N-o-
Chlorophenylmaleimide, N-methylmaleimide, N
Maleimides such as naphthylmaleimide and N-cyclohexylmaleimide; Itaconimides such as N-phenylitaconimide, N-methylitaconimide, N-cyclohexylitaconimide; N-phenylcitraconimide, N-methylcitraconimide, N-cyclohexyl Examples thereof include citraconimides such as citraconimide.

The amount of each of these monomers used is not particularly limited, in order to improve the heat resistance and color resistance of the resulting aromatic vinyl-based copolymer, and the amount of unreacted monomer. In order to increase the polymerization yield by reducing the amount of the aromatic vinyl monomer, the ratio of the aromatic vinyl monomer is 50 to
85 wt%, preferably 55-80 wt%, unsaturated nitrile monomer 5-30 wt%, preferably 10-25 wt%
And the unsaturated dicarboxylic acid imide monomer is 2.5 to 40
%, Preferably 5 to 35% by weight.

In the present invention, in addition to the above monomers, other monomers copolymerizable with the above monomers can be added and polymerized. The amount of such other monomer is 10% in the total monomer used for the polymerization in order to improve the heat resistance and the color resistance of the resulting aromatic vinyl copolymer. weight%
The following is preferable. Examples of such other monomers include acrylic acid esters such as methyl acrylate and ethyl acrylate; methacrylic acid esters such as methyl methacrylate and ethyl methacrylate; vinyl halides such as vinyl chloride. You can

In the present invention, a mixture of the various monomers described above,
In the first stage polymerization, the polymerization is carried out in an aqueous medium in the presence of an oil-soluble polymerization initiator.

The amount of water used is selected from the range of 100 to 500 parts by weight, preferably 150 to 400 parts by weight, based on 100 parts by weight of the mixture of various monomers.

As the oil-soluble initiator used in the first stage polymerization, known ones can be used without any limitation. In particular, in order to improve the coloring resistance of the resulting aromatic vinyl-based monomer, the polymerization initiator having a 10-hour half-life temperature of 60 to 80 ° C. or the 10-hour half-life temperature is
A combination of a polymerization initiator and a reducing agent, which is 120 to 160 ° C., is used. Examples of the oil-soluble polymerization initiator having a 10-hour half-life temperature of 60 to 80 ° C. include peroxides such as benzoyl peroxide, lauroyl peroxide and t-butylperoxyisobutyrate; azo such as azobisisobutyronitrile. Examples include a system polymerization initiator.

On the other hand, examples of the oil-soluble polymerization initiator having a 10-hour half-life temperature of 120 to 160 ° C. include peroxides such as diisopropylbenzene hydroperoxide and cumene hydroperoxide, and the above-mentioned peroxides and rhidium formaldehyde. A redox-based polymerization initiator composed of a reducing agent such as

The amount of the oil-soluble polymerization initiator used is preferably 0.2 to 3 parts by weight with respect to 100 parts by weight of all the monomers used in the first stage polymerization.

In the first-stage polymerization, the above-mentioned monomer and the oil-soluble polymerization initiator can be added all at once to the aqueous medium for polymerization, but a method in which these are divided into two parts and added to the aqueous medium for polymerization. Are preferably used from the viewpoint of coloring resistance of the obtained aromatic vinyl-based copolymer. When the polymerization is carried out in two steps, the amount of the first monomer used is 85 to 98% by weight of the aromatic vinyl-based monomer as a proportion of the total amount of each monomer used.
It is preferable that the unsaturated nitrile monomer is in the range of 5 to 50% by weight, and the unsaturated dicarboxylic acid imide monomer is in the range of 40 to 80% by weight. Further, the oil-soluble polymerization initiator may be added in portions according to the amount ratio of the monomers to be added in portions.

The rest of the monomer and the oil-soluble polymerization initiator added at the first time are added at the second time and the polymerization is carried out. The second addition timing of the monomer is preferably a timing at which the polymerization yield reaches 70% by weight or more from the viewpoint of the coloring resistance of the obtained aromatic vinyl-based copolymer.

When the polymerization yield in the first stage polymerization reaches 80% by weight or more, the second stage polymerization is carried out in the presence of the water-soluble polymerization initiator. When the second-stage polymerization is carried out at a polymerization yield of less than 80% by weight in the first-stage polymerization, the heat resistance and the coloring resistance of the obtained aromatic vinyl-based copolymer are deteriorated, which is not preferable.
The polymerization yield in the first stage polymerization is usually 80% by weight or more. At the time of starting the second stage polymerization, the polymerization yield of the first stage polymerization was 80
It is preferable to select from the range of up to 95% by weight.

The second-stage polymerization may be carried out in a polymerization tank separate from the first-stage polymerization, but normally, the water-soluble polymerization initiator and the radical-polymerizable vinyl monomer which are in the same polymerization tank after the first-stage polymerization are used. This is done by adding the body.

As the water-soluble polymerization initiator, known ones can be used without any limitation. For example, ammonium persulfate and potassium persulfate can be preferably used. The water-soluble polymerization initiator may be used in an amount of 0.01 to 0.5 part by weight based on 100 parts by weight of the total amount of the monomers added in the second stage polymerization.

As the radically polymerizable vinyl monomer added in the second stage polymerization, a vinyl monomer that can be polymerized in the presence of a water-soluble polymerization initiator is adopted without any limitation. For example, the above-mentioned unsaturated nitrile-based monomer, acrylic acid ester, methacrylic acid ester or vinyl halide can be preferably used.
The amount of these vinyl monomers used is preferably in the range of 0.05 to 10 parts by weight based on 100 parts by weight of all the monomers used in the first stage polymerization.

In the first-stage polymerization and the second-stage polymerization in the present invention, a dispersant and an emulsifier are used appropriately. Examples of the dispersant include partially saponified polyvinyl acetate, methyl cellulose, sodium polyacrylate, sodium sulfate, and the like, and examples of the emulsifier include sodium lauryl sulfate, 2-diethylhexyl sodium sulfosuccinate, sodium dodecylbenzenesulfonate, and the like. These may be used alone or in combination of two or more. The amount of the dispersant and the emulsifier used is preferably 0.5 to 3 parts by weight with respect to 100 parts by weight of water. Furthermore, in order to control the molecular weight, 2-
Mercaptoethanol, t-dodecyl mercaptan, n
-A chain transfer agent such as dodecyl mercaptan is used.
The amount used is 0 to 2 parts by weight, preferably 0 to 1.5 parts by weight, based on all the monomers. The polymerization temperature is 50 to 8 for the first stage polymerization.
5 ℃, preferably from 55 ~ 70 ℃, the second stage polymerization is 55 ℃
It is preferably adopted from the range of up to 90 ° C, preferably from 60 to 85 ° C.

Further, in the present invention, the above-mentioned various monomers are polymerized in the presence of an inorganic filler to obtain an aromatic vinyl-based copolymer containing the inorganic filler. The amount of the inorganic filler is in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the total amount of all the monomers, in consideration of the heat resistance and the coloring resistance of the obtained aromatic vinyl copolymer. Is preferred. As the inorganic filler, silica, calcium silicate, aluminum silicate, glass fiber magnesium silicate,
Known substances such as carbon black, clay, talc, graphite, calcium carbonate, titanium oxide and iron oxide can be used without any limitation. Among these, silica,
It is preferable to use silicon compounds such as aluminum silicate, calcium silicate, and magnesium silicate, and calcium carbonate.

The aromatic vinyl copolymer obtained by the method of the present invention can be used alone. Further, in order to improve the heat resistance of the other thermoplastic resin, it can be used as a mixture with other thermoplastic resin. Other thermoplastic resins include acrylonitrile-styrene copolymers, styrene polymers,
Examples thereof include acrylonitrile-styrene-methyl methacrylate copolymer, acrylonitrile-butadiene-styrene copolymer, vinyl chloride polymer, vinyl acetate-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, polycarbonate polymer and the like. It is sufficient to use the aromatic vinyl copolymer obtained in the present invention in the range of 2.5 to 100 parts by weight based on 100 parts by weight of these thermoplastic resins.

(Effect) The aromatic vinyl-based copolymer obtained by the method of the present invention has excellent heat resistance. Moreover, since it does not yellow even when molded and has excellent coloring resistance, the above-mentioned copolymer can be molded by a known method such as injection molding, extrusion molding or blow molding. Therefore, the aromatic vinyl-based copolymer obtained in the present invention is used in a field requiring heat resistance, for example, a housing for electric / electronic parts, a hot water supply pipe, an automobile member, a window frame, a blow molded product, a video. It can be suitably used for disks and the like.

(Examples) Examples and comparative examples are given below to more specifically describe the present invention, but the present invention is not limited to these examples.

Various measured values displayed in Examples and Comparative Examples were measured by the following measuring methods.

1. Viscosity measurement (η _SP ): N—N dimethylformamide solution was used for measurement at a concentration of 0.5 g / 100 cc at 30 ° C.

2. Beakt softening temperature: Measured under a load of 5 kg according to JIS-K-7206.

3. Transparency / Turbidity: Σ80 Color Measuri manufactured by JEOL Ltd.
Measurement was performed using a 3 mmt molded plate with the ng System.

4. Yellowness: The following formula based on JIS-K-7103 The yellowness was calculated at.

The symbols used in the following examples indicate the following monomers.

αMSt: α-Methylstyrene St: Styrene PMSt: P-Methylstyrene AN: Acrylonitrile MAN: Methacrylonitrile NPMI: N-Phenylmaleimide NCHMI: N-Cyclohexylmaleimide NoCPMI: N-Orthochlorophenylmaleimide NPII: N-Phenylitaconimide NCHII: N-cyclohexylitaconimide VC: Vinyl chloride MA: Methyl acrylate MMA: Methyl methacrylate Example 1 A 5 l reactor was charged with 2500 parts of water and 20 parts of sodium lauryl sulfate, and then 650 parts of α-methylstyrene and acrylonitrile. Charge 50 parts, 100 parts N-phenylmaleimide,
After sufficiently purging with nitrogen, the temperature was raised to 60 ° C., 4 parts of lysium formaldehyde sulfoxylate, 0.2 part of sodium ethylenediamine diacetate, and 40 parts of water-soluble containing 0.01 part of ferric sulfate heptahydrate were added, and then diisopropyl Polymerization was initiated by adding 1.5 parts of benzene hydroperoxide.
When the polymerization yield of the mixture reached about 80% by weight, a mixed solution of 50 parts of α-methylstyrene, 100 parts of acrylonitrile, 100 parts of N-phenylmaleimide and 1 part of diisopropylbenzene hydroperoxide was added to carry out polymerization. I continued. After 1 hour, 1.5 parts of diisopropylbenzene hydroperoxide was added. Polymerization yield of the mixture is about 8
When the reaction mixture reached 5% by weight, the temperature of the reaction mixture was raised to 80 ° C., an aqueous solution of 0.5 parts of potassium persulfate dissolved in 50 cc of water was added, and then 5 parts of acrylonitrile was added to carry out polymerization. Acrylonitrile 5 was added after polymerization for 1 hour.
Parts were added and the polymerization was completed for 2 hours to complete the polymerization. The resulting mixture is salt-folded with calcium chloride, and after dehydration by filtration,
It was dried to obtain a white powder of an aromatic vinyl-based copolymer. The polymerization yield was 98% by weight. Viscosity (η _SP ) is 0.42
It was dl / g.

The aromatic vinyl copolymer obtained by the above method is
Roll forming was performed at 0 ° C., and then press forming was performed at 180 ° C. to obtain a formed plate for measuring physical properties.

Beakt softening temperature 145 ° C, transparency 87%, turbidity 7
%, And the yellowness was 11.

Examples 2 to 7 Polymerization was carried out in the same manner as in Example 1 except that the amount ratio of monomers was changed as shown in Table 1. The results are shown in Table 1.

Examples 8 to 11 N-phenylmaleimide used in Example 1 was changed to N-cyclohexylmaleimide, diisopropylbenzene hydroperoxide was changed to cumene hydroperoxide, and 4 parts of t-dodecyl mercaptan was used twice in the first stage polymerization. Polymerization was carried out in the same manner as in Example 1 except that the vinyl monomers added and added in the second stage polymerization were changed to those shown in Table 2. The results are shown in Table 2.

Example 12 2500 parts deionized water, 20 parts sodium lauryl sulfate, α-
A mixture of 600 parts of methyl styrene, 50 parts of acrylonitrile, 100 parts of N-cyclohexylmaleimide, 4 parts of t-dodecyl mercaptan, and 4 parts of azobisisobutyronitrile was sufficiently dispersed using a homogenizer, and then 70 ° C. The temperature was raised to and polymerization was started. When the polymerization yield of the above mixture reached 80%, α-methylstyrene
A mixture of 50 parts, 100 parts of acrylonitrile, 100 parts of N-cyclohexylmaleimide, 4 parts of t-dodecyl mercaptan and 4 parts of azobisisobutyronitrile was added.
Continuously added over a period of 1 minute, and after polymerization for 1 hour, 2 parts of azobisisobutyronitrile was added to the reaction vessel.
Polymerization was carried out for 1 hour. At this point, the polymerization yield was 85% by weight. Then, as a two-stage polymerization, the reaction mixture was heated to 80 ° C., and then 0.5 parts of potassium persulfate dissolved in 40 parts of water,
Acrylonitrile (5 parts) was added, and 1 hour later, acrylonitrile (5 parts) was added and polymerization was further performed for 1 hour to complete the polymerization. The obtained mixture was salt-broken with calcium chloride, dehydrated by filtration, and dried to obtain a white powder. The polymerization yield is
It was 94% by weight. The viscosity (η _SP ) of the obtained aromatic vinyl-based copolymer was 0.21 dl / g. Further, the Beecut softening temperature was 142 ° C., the transparency was 86%, the turbidity was 8%, and the yellowness was 8.

Example 13 Polymerization was performed in the same manner as in Example 12, except that the azobisisobutyronitrile used in Example 12 was changed to benzoyl peroxide. The polymerization yield was 93% by weight. The viscosity (η _SP ) of the obtained aromatic vinyl copolymer is 0.25 dl / g
Met. Also, the Beakut softening temperature was 140 ° C, the transparency was 84%, the turbidity was 11%, and the yellowness was 12.

Example 14 A polymer was obtained in the same manner as in Example 12 except that 20 parts of sodium lauryl sulfate used in Example 12 was changed to 30 parts of sodium sulfate and 3 parts of sodium polyacrylate.
The yield was 92% by weight. The viscosity (η _SP ) of the obtained aromatic vinyl copolymer was 0.19 dl / g. The Beekat softening temperature was 139 ° C., the transparency was 91%, the turbidity was 8%, and the yellowness was 7.

Example 15 2500 parts deionized water, 20 parts sodium lauryl sulfate, α-
A mixture consisting of 700 parts of methyl styrene, 150 parts of acrylonitrile, 150 parts of N-cyclohexylmaleimide, and 6 parts of azobisisobutyronitrile was thoroughly and uniformly dispersed using a homogenizer, and then the temperature was raised to 70 ° C to start polymerization. did. When the polymerization yield reached about 85% by weight, the reaction mixture was heated to 80 ° C., 0.5 parts of potassium persulfate dissolved in 40 parts of water was added, 5 parts of acrylonitrile was added, and further 1 hour later. 5 parts of acrylonitrile was added and polymerization was carried out for 2 hours. The polymerization yield was 92% by weight. The viscosity (η _SP ) of the obtained aromatic vinyl copolymer was 0.18 dl / g. In addition, the Beecut softening temperature is 130 ° C, and the transparency is 8
The turbidity was 7%, the turbidity was 12%, and the yellowness was 16.

Examples 16 to 18 Polymerization was carried out in the same manner as in Example 1 except that the types of monomers used in Example 1 were changed as shown in Table 3, to obtain aromatic vinyl copolymers. The results are shown in Table 3.

Example 19 Aromatic vinyl copolymer was prepared in the same manner as in Example 1 except that 5 parts of silica (Fineseal, Tokuyama Soda Co., Ltd.) was charged as an inorganic filler together with various monomers in a 5 l reactor. Got The polymerization yield was 97%. The Beakt softening temperature was 146 ° C, the transparency was 65%, the turbidity was 45%, and the yellowness was 12.

Example 20 The procedure of Example 19 was repeated, except that the inorganic filler silica used in Example 19 was changed to an aluminum silicate compound (Shiraishi Kogyo Minex). As a result, the polymerization yield was 96%. Also, the Bee-cut softening temperature is 145
C., transparency was 78%, turbidity was 30%, and yellowness was 11.

Comparative Example 1 A polymer was obtained by the same polymerization method without adding the potassium persulfate used in Example 1. The yield was 90% by weight.
The viscosity (η _SP ) of the obtained polymer was 0.12 dl / g.
Further, the Bee-cut softening temperature was 115 ° C., the transparency was 85%, the turbidity was 9%, and the yellowness was 48.

Comparative Example 2 Example 12 without the addition of the potassium persulfate used in Example 12
A polymer was obtained by the same polymerization method as described above. However, since the polymerization yield was low, the polymerization time was extended to 12 hours. The polymerization yield was 82% by weight. The viscosity (η _SP ) of the obtained polymer was 0.09 dl / g. Also, the Beekat softening temperature is 109 ° C, transparency is 84%, turbidity is 20%, yellowness is 15
Met.

Claims (1)

[Claims] 1. A polymerization yield of a mixture of an aromatic vinyl monomer, an unsaturated nitrile monomer and an unsaturated dicarboxylic acid imide monomer in an aqueous medium in the presence of an oil-soluble polymerization initiator. 80
A method for producing an aromatic vinyl-based copolymer, characterized in that the polymerization is carried out until the amount reaches at least wt%, and then the radical-polymerizable vinyl monomer is added to carry out the polymerization in the presence of a water-soluble polymerization initiator. .