JPH0419250B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a maleimide copolymer with excellent heat resistance. More specifically, the present invention relates to a method for efficiently producing a maleimide copolymer having a homogeneous copolymerization composition by suspension polymerization. It is known that a maleimide copolymer formed by copolymerizing a maleimide monomer and a vinyl monomer has a high heat distortion temperature. However, since maleimide monomers have the property of being extremely copolymerizable with vinyl monomers, it is difficult to copolymerize a monomer mixture with an aromatic vinyl monomer under normal radical polymerization conditions. In the case of a wide range of monomer charge compositions, an alternating copolymer with a molar ratio of maleimide monomer and aromatic vinyl monomer of 1:1 is preferentially produced ( R.M. Joshi,
``Makromol. In order to obtain a homogeneous copolymer containing 50 mol% or less of maleimide monomer, maleimide was added to the polymerization system in which vinyl monomer was introduced and polymerization was initiated, as seen in U.S. Pat. No. 2,971,939. A method has been proposed in which the system monomer is fed at a rate below a certain rate, but since this method requires polymerization in bulk or in a solution state, a desolvent or demonomer device is required, and after the completion of polymerization, The disadvantage is that the process for recovering the copolymer is complicated. Therefore, the present inventors conducted extensive research with the aim of efficiently producing a homogeneous maleimide copolymer through suspension polymerization, which allows for easy recovery of the copolymer. The inventors have discovered that the above object can be achieved by using a charging composition of 1 and adding part or all of a specific monomer therein during polymerization, and have thus arrived at the present invention. That is, the present invention provides (A) α-methylstyrene from 30 to
80% by weight, (B) N-substituted maleimide monomer 10-50
Weight%, (C) vinyl cyanide monomer 5-40% by weight
and (D) When carrying out suspension polymerization of a monomer charge composition consisting of 3 to 60% by weight of aromatic vinyl monomers other than α-methylstyrene, the above monomers (A), (B) and (C )
or a monomer mixture consisting of the entire amount of (A), (B), and (C) and a part of (D) is charged into a suspension polymerization system to start polymerization, and during the polymerization, the above monomer ( The present invention provides a method for producing a maleimide copolymer, characterized in that the entire amount or a portion of D) is added continuously and/or intermittently to complete the polymerization. The N-substituted maleimide monomer (B) used in the present invention is a compound represented by the following general formula (), and specifically, maleimide, N-methylmaleimide,
N-ethylmaleimide, N-isopropylmaleimide, N-t-butylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-
-p-chlorophenylmaleimide and N-naphthylmaleimide, among others, N-
-phenylmaleimide and N-cyclohexylmaleimide are preferably used. (In the formula, R ₁ , R ₂ and R ₃ each independently represent hydrogen, halogen, or a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms.) Furthermore, vinyl cyanide monomer (C) used in the present invention Examples of the acrylonitrile include acrylonitrile, methacrylonitrile, and α-chloroacrylonitrile, and among them, acrylonitrile is preferably used. Further, the aromatic vinyl monomers other than (D) α-methylstyrene used in the present invention include styrene, p
- Methylstyrene and p-t-butylstyrene, among others styrene and p-t-butylstyrene.
-Butylstyrene is preferably used. In the present invention, the charging composition of the above monomers (A) to (D) is
(A) 30-80% by weight of α-methylstyrene, especially 35-75% by weight, (B) 10-50% by weight of N-substituted maleimide monomer, especially 15-45% by weight, (C) Vinyl cyanide monomer A proportion should be selected consisting of 5 to 40% by weight, especially 10 to 35% by weight, and 3 to 60% by weight, especially 5 to 55% by weight, of aromatic vinyl monomers other than (D) α-methylstyrene. . Here, (A) α-methylstyrene is 30% by weight
If it is less than 80% by weight, the heat distortion temperature of the resulting maleimide copolymer will not be high enough, and if it exceeds 80% by weight, the polymerization time will be significantly longer, which is not preferable. Also (B)
If the N-substituted maleimide monomer is less than 10% by weight, the resulting maleimide copolymer will not have a sufficient heat distortion temperature, and if it exceeds 50% by weight, the impact strength of the maleimide copolymer will be significantly reduced. Undesirable. Furthermore, if the vinyl cyanide monomer (C) is less than 5% by weight, the impact strength of the resulting maleimide copolymer will not be sufficiently high, and if it exceeds 40% by weight, thermal discoloration will be significant. Furthermore, if the aromatic vinyl monomer other than (D) α-methylstyrene is less than 3% by weight, the impact strength of the maleimide copolymer obtained will be insufficient, and if it exceeds 60% by weight, the heat distortion temperature will be extremely high. This is not preferable because it lowers the temperature. In the present invention, a maleimide copolymer is produced by subjecting the above-mentioned specific monomer charging composition to suspension polymerization. Suspension polymerization here refers to a method in which polymerization is carried out by suspending a mixture of an initiator and monomer by vigorously stirring it in the presence of an inorganic or organic suspending agent using water as a medium. be. There are no particular restrictions on the suspending agent used in suspension polymerization, and ordinary suspending agents for radical polymerization can be used. In addition, the polymerization initiator is not particularly limited as long as it is a radical generating initiator, such as azobisisobutyronitrile, azobiscyclohexanenitrile, azobismethylpropionitrile, azobisdimethylvaleronitrile, etc. Initiators, peroxide-based radical generating initiators such as benzoyl peroxide, ditertiary butyl peroxide, and tertiary butyl peroxybenzoate are used, and among them, azobisdimethylvaleronitrile and azobisisobutyronitrile are preferred. used. Furthermore, a chain transfer agent, a lubricant, a bluing agent, etc. can be mixed into the monomer mixture as required. In the present invention, when carrying out suspension polymerization of the above monomer charge composition, first the above monomers (A), (B) and (C) are
or a monomer mixture consisting of the entire amount of (A), (B), and (C) and a part of (D) is charged into a suspension polymerization system to start polymerization, and during the polymerization, the above monomer ( It is important to add all or part of D) continuously and/or intermittently. Here, the above monomers (A) to (D)
When starting suspension polymerization by charging the entire amount of This is not preferable because a copolymer containing the monomer (C) as a main component is produced and the copolymer itself becomes extremely thermally colorable. In addition, if the monomer to be added subsequently is (A) α-methylstyrene, this monomer itself does not have as strong a copolymerizability with maleimide monomers as styrene or pt-butylstyrene; In this case, the maleimide monomer is selectively copolymerized with other monomers such as styrene and pt-butylstyrene, making it impossible to obtain a homogeneous maleimide copolymer. Furthermore, since α-methylstyrene is difficult to polymerize, if it is subsequently added to the polymerization system, a considerable amount of α-methylstyrene remains until the late stage of polymerization, resulting in a low polymerization rate. Furthermore, if the monomer to be added is vinyl cyanide monomer (C), a copolymer with a high copolymerization amount of this monomer can be obtained in the latter half of the polymerization, and the heat of the copolymer itself This is not preferable because it causes significant coloring. In this way, the monomers to be added additionally include (D)α- such as styrene and pt-butylstyrene.
Aromatic vinyl monomers other than methylstyrene are suitable, and a maleimide copolymer with a homogeneous copolymerization composition can thereby be obtained. The monomer (D) can be added continuously and/or intermittently to the polymerization system, for example, by adding an initiator or a chain transfer agent, etc. using an ordinary monomer supply device. Examples include a method of mixing and supplying. The amount of monomer (D) added here may be the entire amount of the above-mentioned charging composition, or may be a part thereof. However, the monomer (D) used
15% or more should be added subsequently; if the amount added subsequently is too small, the thermal coloring property will be significant, similar to the copolymer obtained by adding the entire amount of monomer (D) at the beginning and polymerizing it. Undesirable. Thus, the maleimide copolymer obtained by the method of the present invention has a narrow composition distribution and is free from thermal coloring, and the resin composition obtained by blending it with other polymers also has an excellent balance of Izot impact and fluidity. There is. The maleimide copolymer obtained by the method of the present invention has excellent miscibility with rubber-modified resins known as ABS resins and MBS resins,
By mixing these, the impact strength of the maleimide copolymer can also be improved. Also,
Vinyl copolymers such as styrene-acrylonitrile copolymer, α-methylstyrene-acrylonitrile copolymer, and styrene-methyl methacrylate copolymer, polyamide-based polymers such as nylon, polyethylene terephthalate, and polybutylene. It can be mixed with other thermoplastic resins such as polyester polymers represented by terephthalate, polycarbonate, polyacetal, polyphenylene sulfide, polyetheretherketone, polyimide, polyamideimide, and polyphenylene oxide, and can be used in various It is also possible to produce maleimide resin compositions with specific properties. Furthermore, the maleimide copolymer obtained by the production method of the present invention or the maleimide resin composition obtained by blending with other thermoplastic resins may be added with a conventional hindered phenol antioxidant, phosphorus antioxidant, and sulfur. It is also possible to improve thermal stability by adding an antioxidant such as a system antioxidant, and to further improve fluidity by adding a lubricant. Further, fiber reinforcing agents such as glass fibers, inorganic fillers, colorants, pigments, conductive materials, and the like may be added depending on the purpose. Furthermore, flame retardation can be achieved by mixing general halogenated organic compound flame retardants such as tetrapromobisphenol A, decapromobiphenyl ether, and brominated polycarbonate with antimony oxide. As explained above, by the method of the present invention, a maleimide copolymer with a uniform copolymerization composition and no heat coloring can be efficiently obtained, and the resulting maleimide copolymer can be used with other thermally colored copolymers such as ABS resin. A maleimide resin composition obtained by blending with a plastic resin is
Excellent heat resistance and mechanical properties are balanced. The present invention will be further explained below using reference examples and examples. In addition, BS in reference examples and examples
−HDT is ASTM− according to BS standard 2872 102C.
HDT is the heat distortion temperature measured according to ASTM standard D648-56. In addition, the Izotsu impact strength is
Measured according to ASTM D256-56 Method A. For thermal coloring, the maleimide copolymer was left in a hot air dryer at 200°C for 1 hour, and the degree of coloring was visually determined. Melt viscosity was 0.5mm using a Koka type flow tester.
260℃ with a load of 50Kg/ ^cm2 applied to a φ×1.0mm nozzle.
It was measured with Moreover, parts represent parts by weight, and % represents weight %. Example 1 [Preparation of maleimide copolymer (A-1)] 0.3 parts of acrylamide-methyl methacrylate copolymer (suspending agent) was placed in a polymerization tank equipped with a reflux condenser, a stirrer, and a monomer supply device. An aqueous solution in which 0.5 part of sodium phosphate was dissolved in 200 parts of deionized water was charged and stirred vigorously. Then α−
25 parts of methylstyrene, 30 parts of N-phenylmaleimide
parts, 20 parts of acrylonitrile, 15 parts of styrene and 0.5 parts of azobisdimethylvaleronitrile (initiator)
The temperature inside the polymerization tank was 50℃.
suspension polymerization was started. 4 hours after the start of polymerization, 10 parts of styrene was charged into the polymerization tank, and 5 hours after the polymerization initiator was added, the polymerization temperature was raised to 95°C and polymerization was continued for a further 3 hours. The polymerization rate was determined by gas chromatography and was 97%. The obtained polymer slurry was filtered, washed with water, and then dried to obtain maleimide copolymer A-1. Example 2 [Preparation of maleimide copolymer (A-2)] In the same polymerization tank as in Example 1, 0.3 parts of acrylamide-methyl methacrylate copolymer (suspending agent) and 0.5 parts of sodium phosphate were deionized. An aqueous solution dissolved in 200 parts of water was charged and stirred vigorously. Then α
-40 parts of methylstyrene, N-phenylmaleimide
A polymerization tank in which a monomer mixture containing 30 parts of acrylonitrile, 20 parts of acrylonitrile, 0.5 parts of azobisisobutyronitrile (initiator), and 0.5 parts of azobiscyclohexanenitrile (initiator) was kept at 50°C. suspension polymerization was started. 10 parts of styrene was continuously fed into the polymerization tank over 1 hour after the start of polymerization. Four hours after the start of polymerization, the polymerization temperature was raised to 95°C, and the polymerization was further continued for 3 hours. The polymerization rate was determined by gas chromatography and was 98%. The obtained polymer slurry was filtered, washed with water, and then dried to obtain maleimide copolymer A-2. Example 3 [Preparation of maleimide copolymer (A-3)] In a polymerization tank similar to Example 1, 0.3 parts of acrylamide-methyl methacrylate copolymer (suspending agent) and 0.5 parts of sodium phosphate were added to deionized water. 200 parts of an aqueous solution was charged and stirred vigorously. Then α−
A monomer mixture containing 30 parts of methylstyrene, 20 parts of N-cyclohexylmaleimide, 25 parts of acrylonitrile, 15 parts of pt-butylstyrene, and 0.5 parts of azobisisobutyronitrile (initiator) was heated to a polymerization tank temperature of 70 parts. The mixture was charged into a polymerization tank kept at ℃ and suspension polymerization was started. 10 parts of pt-butylstyrene was continuously supplied to the polymerization tank over a period of 2 hours after the start of polymerization.
4 hours after the start of polymerization, the polymerization temperature was raised to 95°C,
Polymerization was continued for an additional 3 hours. The polymerization rate was determined by gas chromatography and was 97%. The obtained polymer slurry was filtered, washed with water, and then dried to obtain maleimide polymer A-3. Comparative Example 1 [Production of maleimide copolymer (A'-1)] In the same polymerization tank as in Example 1, 0.3 parts of acrylamide-methyl methacrylate copolymer (suspending agent) and 0.5 parts of sodium phosphate were removed. An aqueous solution dissolved in 200 parts of ionized water was charged and stirred vigorously. next,
25 parts α-methylstyrene, 30 parts N-phenylmaleimide, 25 parts acrylonitrile, 20 parts styrene and azobisdimethylvaleronitrile (initiator)
Add 0.5 part of the monomer mixture to the temperature in the polymerization tank.
The mixture was charged into a polymerization tank kept at 50°C, and suspension polymerization was started. Four hours after polymerization, the temperature was raised to 95°C, and polymerization was further continued for 3 hours. The polymerization rate was determined by gas chromatography and was 96%. The obtained polymer slurry was filtered, washed with water and dried to obtain maleimide copolymer A'-
I got 1. Comparative Example 2 [Production of maleimide copolymer (A'-2)] In the same polymerization tank as in Example 1, 0.3 parts of acrylamide-methyl methacrylate copolymer (suspending agent) and 0.5 parts of sodium phosphate were removed. An aqueous solution dissolved in 200 parts of ionized water was charged and stirred vigorously. next,
30 parts of N-phenylmaleimide, acrylonitrile
A monomer mixture containing 20 parts of styrene, 25 parts of styrene, and 0.5 parts of azobisisobutyronitrile (initiator) was charged into a polymerization tank whose internal temperature was maintained at 70°C.
Suspension polymerization was started. Over 2 hours after the start of polymerization,
25 parts of α-methylstyrene was continuously fed into the polymerization tank. Six hours after the start of polymerization, the polymerization temperature was raised to 95°C, and polymerization was continued for an additional 3 hours. The polymerization rate was determined by gas chromatography and was 92%. The obtained polymer slurry was filtered, washed with water, and then dried to obtain a maleimide copolymer (A'-2). Comparative Example 3 [Production of maleimide copolymer (A'-3)] In the same polymerization tank as in Example 1, 0.3 parts of acrylamide-methyl methacrylate copolymer (suspending agent) and 0.5 parts of sodium phosphate were removed. An aqueous solution dissolved in 200 parts of ionized water was charged and stirred vigorously. next,
A monomer mixture containing 25 parts of α-methylstyrene, 30 parts of N-phenylmaleimide, 25 parts of styrene, and 0.5 parts of azobisdimethylvaleronitrile was charged into a polymerization tank whose internal temperature was maintained at 50°C, and suspended. Turbid polymerization started. 20 parts of acrylonitrile was continuously fed into the polymerization tank over 2 hours after the start of polymerization.
Four hours after the start of polymerization, the polymerization temperature was raised to 95°C, and polymerization was continued for an additional 3 hours. The polymerization rate was determined by gas chromatography and was 93%. The obtained polymer slurry was filtered, washed with water, and dried to obtain a maleimide copolymer (A'-3). Comparative Example 4 [Production of maleimide copolymer (A'-4)] In the same polymerization tank as in Example 1, 0.3 parts of acrylamide-methyl methacrylate copolymer (suspending agent) and 0.5 parts of sodium phosphate were removed. An aqueous solution dissolved in 200 parts of ionized water was charged and stirred vigorously. next,
A polymerization tank in which a monomer mixture containing 20 parts of α-methylstyrene, 30 parts of N-phenylmaleimide, 45 parts of acrylonitrile, and 0.5 parts of azobisdimethylvaleronitrile (initiator) was kept at 50°C. suspension polymerization was started. 4 hours after polymerization, 5 parts of styrene was charged into the polymerization tank, and 5 hours after the start of polymerization, the polymerization temperature was raised to 95°C, and polymerization was continued for an additional 3 hours. The polymerization rate was determined by gas chromatography and was 95%. The resulting polymer slurry is filtered, washed with water, and dried to form a maleimide copolymer.
A′-4 was obtained. Comparative Example 5 [Production of maleimide copolymer (A'-5)] In the same polymerization tank as in Example 1, 0.3 parts of acrylamide-methyl methacrylate copolymer (suspending agent) and 0.5 parts of sodium phosphate were removed. An aqueous solution dissolved in 200 parts of ionized water was charged and stirred vigorously. next,
10 parts α-methylstyrene, 5 parts N-phenylmaleimide, 20 parts acrylonitrile, 50 parts styrene and azobisdimethylvaleronitrile (initiator)
Add 0.5 part of the monomer mixture to the temperature in the polymerization tank.
The mixture was charged into a polymerization tank kept at 50°C, and suspension polymerization was started. Over 2 hours after the start of polymerization, 15 parts of styrene was continuously fed into the polymerization tank. Four hours after the start of polymerization, the polymerization temperature was raised to 95°C, and polymerization was continued for an additional 3 hours. The polymerization rate was determined by gas chromatography and was 96%. The obtained polymer slurry was filtered, washed with water, and then dried to obtain maleimide copolymer A'-5. Maleimide copolymer A- obtained in Examples 1 to 3
Table 1 shows the BS-HDT and thermal colorability of the maleimide copolymers A'-1 to A'-5 obtained in Comparative Examples 1 to 3 and Comparative Examples 1 to 4. In addition, 25 parts of these maleimide copolymers and 7.6 parts of ABS resin with a rubber content of 23% are blended,
A maleimide resin composition was obtained by melt-kneading. Then, its physical properties were measured and the results are summarized in Table-1.

[Table] As is clear from Table 1, the maleimide copolymers (A-1 to A-3) obtained by the method of the present invention are
BS-HDT is also high and there is no thermal coloring property. In addition, maleimide resin compositions obtained by blending it are also available.
ASTM-HDT, Izot impact strength and melt viscosity are balanced and excellent. On the other hand, a maleimide copolymer (A'-1) obtained by a method that does not add an aromatic vinyl monomer other than α-methylstyrene, α-methylstyrene or vinyl cyanide monomer Even if an aromatic vinyl monomer other than the maleimide monomer (A'-2,3) obtained by additionally adding and α-methylstyrene is added, the monomer deviates from the composition of the present invention. The maleimide copolymer (A'-4, 5) obtained from the mixture has thermal coloring properties, and the ASTM-HDT, Izod impact strength, and melt viscosity of the maleimide resin composition are Inferior.

Claims (1)

[Claims] 1 (A) α-methylstyrene 30-80% by weight, (B) N-
From 10 to 50% by weight of substituted maleimide monomer, (C) 5 to 40% by weight of vinyl cyanide monomer, and (D) 3 to 60% by weight of aromatic vinyl monomer other than α-methylstyrene. When carrying out suspension polymerization of the monomer charge composition, the total amount of the above monomers (A), (B) and (C) or (A),
A monomer mixture consisting of all of (B) and (C) and a part of (D) is charged into a suspension polymerization system to start polymerization, and during the polymerization, all or part of the above monomer (D) is added. 1. A method for producing a maleimide copolymer, which comprises adding continuously and/or intermittently to complete the polymerization.