JP3297180B2 - Maleimide copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a maleimide copolymer excellent in heat resistance, transparency, mechanical strength and processability.

[0002]

2. Description of the Related Art In the fields of electric equipment and automobiles,
In recent years, the importance of products with an emphasis on design has been increasing.
In response to such a tendency, materials used for them are required to have high mechanical performance, light weight and excellent appearance. In the field where transparency is required to meet such demand, polycarbonate resin belonging to a material field called engineering plastic is used, or SMI which is a copolymer of styrene and N-phenylmaleimide is used.
Resins have been developed and used. Although these resins have excellent heat resistance, the conventionally used AS
Moldability is inferior to resin, and it is hard to say that it is inexpensive in terms of price. In particular, in recent resin products, design is required, and in addition to complicated shapes, thinning for weight reduction has made handling easier at the time of molding process from the viewpoint of improvement of yield, energy saving and resource saving. It is gaining attention as part of the performance of materials. From such a viewpoint, there has been a demand for a resin material having both ease of handling of an AS resin conventionally used in a wide range of fields and heat resistance such as engineering plastic.

[0003] As a method for improving the heat resistance of an AS resin, a method of forming an acrylonitrile-styrene-α-methylstyrene terpolymer resin obtained by polymerizing α-methylstyrene in addition to acrylonitrile and styrene,
Alternatively, a method of using an acrylonitrile-styrene-α-methylstyrene-N-phenylmaleimide quaternary copolymer resin is generally employed. In this case, the inclusion of α-methylstyrene contributes to the improvement of heat resistance,
If the content of α-methylstyrene is small, sufficient heat resistance cannot be obtained, and if it is large, the polymerization rate is slow and it is difficult to obtain a resin with a high degree of polymerization. It has the disadvantage that it is easily decomposed.
In order to overcome such disadvantages of using α-methylstyrene, a heat-resistant resin using a maleimide-based copolymer has been developed. The present inventors have also proposed a maleimide-based copolymer and a method for producing the same in JP-A-2-51514.

[0004]

However, although maleimide copolymers have high heat resistance, they have the drawback that they have lower fluidity when melted than conventional AS resins and are inferior in moldability. Generally, a method of adding a plasticizer, a lubricant, etc. has been adopted as a technique for improving the moldability.
There are adverse effects, such as the need to keep the state of dispersion in the resin constant, the appearance of the molded product being lost during molding, and the reduction in heat resistance, which is the original purpose.

[0005]

Means for Solving the Problems In view of such circumstances, the present inventors have conducted intensive studies on a maleimide-based copolymer excellent in molding processability without deteriorating heat resistance, and have reached the present invention.

Namely it is an aspect of the present invention, a maleimide-based monomer unit (A) 15 to 65 wt%, an aromatic vinyl monomer unit (B) 35 to 85 wt% and shear
A maleimide-based copolymer comprising 15 to 35% by weight of a vinyl halide-based monomer unit (C) (provided that the total amount of the unit components (A) to (C) is 100% by weight); co content of residual maleimide monomer in the polymer is 0.1 wt% or less, and total volatiles other than maleimide monomer is 0.5 wt% or less, (II) a molecular weight 200 or more 1
The content of the oligomer component of 000 or less is 2 to 10% by weight.
Wherein the oligomer component is a maleimide monomer
Comprises a copolymer containing units, (III) yellow index of the copolymer is 30 or less, (IV)
A maleimide-based copolymer, wherein the copolymer has an intrinsic viscosity of 0.3 to 1.5.

The maleimide monomer (A) used in the present invention includes maleimide, N-methylmaleimide,
Ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-toluylmaleimide, N-xylylmaleimide, N-naphthylmaleimide, Nt-butylmaleimide, N-orthochlore Examples include phenylmaleimide, N-orthomethoxyphenylmaleimide, and N-orthobromophenylmaleimide. Of these, N-cyclohexylmaleimide, N-orthochlorophenylmaleimide, N-orthobromomaleimide, and N-phenylmaleimide are preferred, and N-phenylmaleimide is particularly preferred. These maleimide monomers can be used alone or in combination of two or more.

[0008] The content of the maleimide monomer unit (A) in the maleimide copolymer of the present invention is in the range of 15 to 65% by weight, more preferably 20 to 50% by weight. is necessary. When the content of the maleimide-based monomer unit is less than 15% by weight, the original heat resistance is low, and when it exceeds 65% by weight, the flowability is poor and a molded article cannot be obtained during molding. In addition, the resin becomes brittle and causes problems such as cracking when the molded article is detached from the mold.

The aromatic vinyl monomer unit (B) in the present invention includes styrene, α-methylstyrene, paramethylstyrene, t-butylstyrene, chlorostyrene,
Styrene is preferred, including bromostyrene and vinyltoluene. These aromatic vinyl monomers can be used alone or in combination of two or more.

The content of the aromatic vinyl monomer unit (B) in the maleimide copolymer of the present invention is in the range of 35 to 85% by weight, preferably in the range of 40 to 70% by weight. When the content of the aromatic vinyl monomer unit is less than 15% by weight, the resulting maleimide-based copolymer has low fluidity and poor moldability, and when it exceeds 85% by weight, the heat resistance is low. It is not preferable.

Further, as another vinyl monomer unit used as the optional component (C) in the present invention, a vinyl cyanide monomer is used. Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, fumaronitrile and the like, and acrylonitrile is preferred. These other vinyl monomers (C) alone,
Alternatively, two or more types can be used in combination.

[0012] cyanide maleimide copolymer of the present invention
The content of the vinyl monomer (C ) is 15% by weight or more.
Ri, must not exceed 35 wt%, more preferably not exceed 25 wt%. Other vinyl monomer unit is 3
When the amount exceeds 5% by weight, the heat resistance, transparency, impact resistance, workability and the like of the obtained maleimide-based copolymer are impaired.

Further, in the maleimide copolymer of the present invention, the content of the residual maleimide monomer in the copolymer is 0.1% by weight or less, preferably 0.05% by weight or less, and The total volatile components other than the system monomer are 0.5
It should be less than 0.4% by weight, preferably less than 0.4% by weight. If the content of the residual maleimide-based monomer exceeds 0.1% by weight, the copolymer is not only remarkable in coloration but also inferior in transparency, and disadvantages such as thermal coloring and bleed-out during processing are likely to occur. . Further, as the total volatile components other than the maleimide-based monomer in the copolymer, the constituent monomers and the organic solvent and optionally the polymerization initiator used,
Residues of the chain transfer agent can be cited, but if the total amount exceeds 0.5% by weight, problems such as loss of heat resistance of the copolymer and generation of silver streaks during molding are not preferred. .

The maleimide copolymer of the present invention has a molecular weight of
Is 2 to 10% by weight of an oligomer component having a molecular weight of 200 to 1000.
, Preferably in the range of 3 to 9% by weight.
The oligomer component has a maleimide monomer unit.
Comprising a copolymer. The content of the oligomer component was determined by gel permeation chromatography (GP).
It can be determined from the ratio of the area of the peak in the corresponding range to the area of all the peaks in the elution curve of C). The monomer component constituting the oligomer component can be determined by elemental analysis after drying the eluate of the oligomer component separated and collected by GPC to remove the solvent. It is necessary that a maleimide-based monomer unit is contained as a constituent unit of the oligomer component, and an oligomer component not containing a maleimide-based monomer unit is preferable because it reduces the mechanical strength of the copolymer. Absent. The oligomer component needs to have a molecular weight of 200 or more,
An oligomer component having a molecular weight of less than 200 is not preferable since it causes silver streaks during molding.
An oligomer component exceeding 00 is not preferable because it does not contribute to the improvement of fluidity and does not meet the purpose of the present invention. When the content of the oligomer component is less than 2% by weight, the fluidity of the copolymer at the time of melting is low and the molding processability is poor, which is not preferable.
Exceeding 0% by weight is not preferred because the heat resistance and mechanical strength of the copolymer are reduced and coloring during heating is apt to occur.

The maleimide copolymer of the present invention must have a yellow index (yellowness, YI) of 30 or less, preferably 25 or less. This YI indicates a value measured as a value of a molded plate obtained by molding the copolymer, and a vinyl cyanide-based monomer remaining as a residual maleimide-based monomer and other vinyl-based monomers in the copolymer. When a monomer is used, there is a close relationship between the residual amount and the content of the vinyl cyanide monomer residue incorporated into the polymer in the copolymer. Also, as described above, when an excessive oligomer component is contained, YI is affected. In this case, those having a YI of more than 30 are not preferable because heat coloring occurs due to heat treatment during processing and the appearance of the molded article is impaired.

Further, the intrinsic viscosity of the maleimide copolymer of the present invention must be in the range of 0.3 to 1.5, preferably 0.5 to 1.2. The intrinsic viscosity is a value obtained by dissolving a maleimide-based copolymer in N, N-dimethylformamide and measuring at 25 ° C. with an Ubbelohde viscometer. A maleimide-based copolymer having an intrinsic viscosity of less than 0.3 has poor practical mechanical strength and is difficult to withstand practical use, while a maleimide-based copolymer having an intrinsic viscosity of more than 1.5 has a fluidity at the time of melting. The molding processability is inferior.

The maleimide-based copolymer of the present invention has a residual maleimide-based monomer amount, a total volatile content other than the maleimide-based monomer, and a molecular weight containing the maleimide-based monomer as a constituent component of 200 to 1000 as described above. It is necessary to satisfy all the following conditions of the amount of oligomer, YI and intrinsic viscosity.

As a method for producing the maleimide copolymer of the present invention, generally known methods can be employed. In producing the copolymer of the present invention, a polymerization initiator, a chain transfer agent, a heat stabilizer and the like can be added as desired. As the polymerization initiator that can be used as desired when producing the copolymer of the present invention, generally known organic peroxides and azo compounds can be used. Ketone peroxides as organic peroxides,
Peroxy ketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxy esters, peroxy dicarbonates, etc. are used, methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, methyl cyclohexanone peroxide, Acetylacetone peroxide, 1,1-dibutylperoxy-3,3,5-trimethylcyclohexane,
1,1-dibutylperoxycyclohexane, 2,2-di-t-butylperoxybutane, 2,2,4-trimethylpentyl-2-
Hydroperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane, t-butylcumyl peroxide, di-t-butyl peroxide, tris- (t- (Butylperoxy) triazine, di-t-butylperoxyhexahydroterephthalate and the like. Azo compounds include 1,1'-azobis (cyclohexane
-1-carbonitrile), 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis [2- (2-imidazoline-2- Yl) propane] dihydrochloride, azodi-t-octane-2-cyano-2-propylazoformamide, dimethyl 2,2'-azobis (2-methylpropionate), 2,2'-azobis (2-hydroxymethyl And propionitrile). Known chain transfer agents that can be used as desired in producing the copolymer of the present invention can be used, and examples thereof include mercaptans, terpene oils, and α-methylstyrene dimer. As additives such as heat stabilizers that can be used as desired in producing the copolymer of the present invention, generally known additives can be used, but additives that inhibit polymerization or cause adverse effects such as coloring are not preferred. .

[0019]

The present invention will be described below with reference to specific examples.

In the following description, “parts” means “parts by weight”,
“%” Means “% by weight”. Various measuring methods were performed according to the following methods.

The amount of residual monomers in the copolymer was measured by gas chromatography.

The composition ratio of each monomer unit of the copolymer was determined by elemental analysis.

The yellow index (YI) was measured in accordance with ASTM D-1925 by molding a 3 mm-thick plate-like specimen obtained by molding the copolymer at a cylinder temperature of 260 ° C. using a 1 oz. Injection molding machine. Similarly, a test piece was molded, and the Vicat softening temperature was measured according to ASTM D-1525 (5 kg load).

The intrinsic viscosity [η] of the copolymer is expressed as follows:
It was dissolved in N-dimethylformamide and determined at 25 ° C. with an Ubbelohde viscometer.

As an index indicating the formability, the short shot pressure and the spiral flow length at the time of specimen molding were determined and compared. The short shot pressure is the minimum injection pressure required to fill the required amount of resin into the mold, and depends on the molding temperature, the mold, the molding machine, the melt viscosity of the resin, etc. When molding under the conditions, it can be determined that the lower the pressure, the higher the moldability of the resin. Spiral flow length is measured by measuring the length of a molded product obtained by molding at a constant injection pressure using a mold having a width of 1 cm and a thickness of 2 mm and the end of which is opened to the outside of the mold, and compares the fluidity. It is an index and indicates that the larger this value is, the more excellent the moldability of the resin is. In the examples and comparative examples, the values obtained by measuring the lengths of molded products when molded at a cylinder temperature of 260 ° C. and an injection pressure of 30 kg / cm ² G using a 1-oz molding machine are shown.

(Example 1) 20 l subjected to a nitrogen substitution operation
20 parts of N-phenylmaleimide, 40 parts of styrene, 20 parts of acrylonitrile, 20 parts of methyl ethyl ketone, 0.01 part of 1,1′-azobis (cyclohexane-1-carbonitrile), 0.01 part of t- Dodecyl mercaptan (0.05 part) was continuously supplied using a pump and
While continuously maintaining the temperature inside the polymerization reactor at 0 ° C., the polymerization reaction solution was continuously withdrawn by a gear pump provided at the bottom of the polymerization reactor so that the average residence time was 2 hours. Was allowed to stay for about 20 minutes in a heat exchanger maintained at 150 ° C., and then introduced into a 2-vent type 30 mm twin-screw extruder controlled at a barrel temperature of 230 ° C., where the first vent was at atmospheric pressure and the second vent was Was volatilized under a reduced pressure of 20 Torr, and volatile components were volatilized and pelletized with a pelletizer to obtain a maleimide copolymer pellet. Various physical property values of the maleimide-based copolymer were determined and are shown in Table 1.

[0027]

[Table 1]

Comparative Example 1 Using the same apparatus as in Example 1, the temperature of the polymerization reactor was set to 95 ° C., and 1,1′-azobis
0.18 parts of (cyclohexane-1-carbonitrile), t-
Except that dodecyl mercaptan was used in an amount of 0.22 parts, the same operation was carried out to obtain maleimide copolymer pellets. The pellets were molded and measured in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 Using the same apparatus as in Example 1 and Comparative Example 2, the temperature of the polymerization reactor was set to 150 ° C., and 1,1′-azobis (cyclohexane-1-carbonitrile) was used.
0.001 part, t-dodecyl mercaptan 0.005 part
The same operation was performed except that the mixture was used as a part to obtain a maleimide copolymer pellet. The pellets were molded and measured in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 3 Using the same apparatus as in Example 1, 30 parts of N-phenylmaleimide, 30 parts of styrene, 40 parts of methyl ethyl ketone, 0.01 part of azobisisobutyronitrile, 0.01 part of N-octyl mercaptan 0 .4 parts, the temperature in the polymerization reactor was 120 ° C., the average residence time was 90 minutes, and the barrel temperature of the twin screw extruder was 270 ° C. without using the second reactor. The same operation as in Example 1 was performed to obtain a maleimide-based copolymer pellet. The pellets were molded and measured in the same manner as in Example 1. Table 1 shows the results.

(Comparative Example 4) Using the same apparatus as in Example 2, 0.005 part of azobisisobutyronitrile and 0.3 part of N-octylmercaptan were supplied, and the temperature in the polymerization reactor was reduced. The same operation as in Example 2 was performed except that the temperature was changed to 130 ° C., thereby obtaining a maleimide copolymer pellet. The pellets were molded and measured in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 5 Using the same apparatus as in Example 2, 0.4 part of azobisisobutyronitrile and 1 part of N-octylmercaptan were supplied, and the temperature in the polymerization reactor was set to 1
The same operation as in Example 2 was performed except that the temperature was set to 00 ° C., to obtain a maleimide-based copolymer pellet. The pellets were molded and measured in the same manner as in Example 1. Table 1 shows the results.

(Example 2) Using the same apparatus as in Example 1, 25 parts of N-phenylmaleimide, 40 parts of styrene, 15 parts of acrylonitrile, 20 parts of methyl ethyl ketone, 1,
1'-azobis (cyclohexane-1-carbonitrile) 0.0
15 parts, t-dodecyl mercaptan 0.03 parts,
The same operation as in Example 1 was carried out except that the temperature in the polymerization reactor was set to 130 ° C. and the barrel temperature of the twin-screw extruder was set to 250 ° C., to obtain maleimide copolymer pellets. The pellets were molded and measured in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 6 Using the same apparatus as in Example 1, 1,1′-azobis (cyclohexane-1-carbonitrile)
0.1 parts, t-dodecyl mercaptan 0.2 parts,
The same operation as in Example 3 was carried out except that the temperature in the polymerization reactor was changed to 100 ° C., to obtain a maleimide copolymer pellet. The pellets were molded and measured in the same manner as in Example 1. Table 1 shows the results.

(Comparative Example 7) Ethylene bisstearylamide (KAO WAX EB manufactured by Kao Corporation ) generally used as a lubricant in 100 parts of the pellet of Comparative Example 6
P) One part was added and extruded with a 30 mm twin screw extruder at a barrel temperature of 250 ° C. to obtain pellets. The pellets were measured in the same manner as in Example 1. YI was 45, Vicat softening temperature was 146 ° C., short shot pressure was 33 kg / cm ² G, and spiral flow length was 16 cm. .

The Examples and Comparative Examples show that the maleimide copolymer of the present invention has high heat resistance and excellent moldability. When the content of the oligomer component having a molecular weight of 200 to 1000 containing the maleimide monomer as a component outside the scope of the present invention is small, the fluidity is poor, and conversely, the maleimide monomer When the content of the oligomer component having a molecular weight of 200 to 1000 containing the body as a constituent is large, the fluidity is high, but the heat resistance is impaired, and coloring is likely to occur during heating. Further, it can be seen that the maleimide-based copolymer of the present invention has improved fluidity without causing a decrease in heat resistance that occurs when a generally used lubricant or the like is added.

[0037]

The maleimide-based copolymer of the present invention has excellent heat resistance and excellent moldability, and can be easily processed into molded articles in various fields. Can be.

────────────────────────────────────────────────── (5) Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI C08F 220: 44) C08F 220: 44) (56) References JP-A-2-138321 (JP, A) JP-A-61-276807 (JP, A) European Patent Application Publication 509459 (EP, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 212/00-212/32 C08F 222/40 C08F 220/42-220 / 50

Claims (1)

(57) [Claims] 1. A maleimide monomer unit (A) 15 to 6.
5% by weight, aromatic vinyl monomer unit (B) 35 to 85
% By weight and vinyl cyanide monomer unit (C) 15 to
35% by weight (however, the total amount of the unit components (A) to (C) is 10)
0% by weight), wherein (I) the content of the residual maleimide-based monomer in the copolymer is 0.1% by weight or less and the maleimide-based monomer is The total volatile matter other than is 0.5% by weight or less; (II) molecular weight
Is 200 to 1000 oligomer component content
2 to 10% by weight, wherein the oligomer component is
Comprising a copolymer containing imide-based monomer units,
(III) The copolymer has a yellow index of 30 or less, and (IV) the copolymer has an intrinsic viscosity of 0.3 to 1.
5. A maleimide-based copolymer, which is 5.