JP2565697B2 - Method for producing transparent heat-resistant resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a transparent heat-resistant resin comprising an N-substituted maleimide-based copolymer having excellent transparency, heat resistance, weather resistance, and thermal stability. .

b. Conventional Technology As a transparent resin, polymethacrylic acid resin and methyl methacrylate-styrene copolymer resin have been widely used as resins having excellent transparency. But,
Since these resins have low heat resistance, their use is greatly restricted in fields requiring so-called semi-engineering plastic performance, such as high-grade household products, low-power materials, precision industrial materials, and durable materials. Is the current situation.

Eliminating these drawbacks of methyl methacrylate resin,
In order to improve heat resistance, there is a method of copolymerizing a monomer such as α-methylstyrene-methacrylic acid or maleic anhydride with these resins.

c. Problems to be Solved by the Invention However, the methyl methacrylate-based resin obtained by copolymerizing these monomers has improved heat resistance, but has problems in thermal stability, moldability, etc. Since the monomer has a higher refractive index than that of methyl methacrylate, the copolymer exhibits birefringence, and it is often used for optical precision parts such as the above-mentioned fields, optical disks and lenses. I have a problem to solve.

Based on the above findings, the present inventors have earnestly studied in order to obtain a methyl methacrylate-based resin having more excellent heat resistance, and as a result, a specific composition comprising methyl methacrylate, an N-substituted maleimide compound, and styrene has been obtained. By re-polymerizing the copolymer having, by using methyl styrene dimer as a polymerization modifier, coloring of the obtained resin is reduced, and a resin excellent in transparency, heat resistance, weather resistance and thermal stability can be obtained. The present invention has been discovered and the present invention has been reached.

d. Means for Solving the Problems That is, the present invention provides (a) methyl methacrylate 10 to 90% by weight (b) N-substituted maleimide compound 1 to 80% by weight (c) styrene 5 to 80% by weight and ( d) Vinylcyanide compound 100 parts by weight of a monomer consisting of 0 to 20% by weight of methyl styrene dimer
The present invention provides a method for producing a transparent heat-resistant resin, which comprises polymerizing in the presence of 0.01 to 3 parts by weight and adjusting the intrinsic viscosity number of the copolymer to 0.15 to 0.5 dl / g.

(A) The higher the content of methyl methacrylate, the better the transparency of the obtained resin, but the amount used is limited due to the balance with heat resistance, and is usually 10 to 90% by weight, preferably 21% by weight. Or more and less than 84% by weight, more preferably
25-78% by weight, most preferably 35-75% by weight. Ten
If it is less than 10% by weight, the transparency tends to be poor, and if it exceeds 90% by weight, the heat resistance tends to be low.

(B) N-substituted maleimide, N-cyclohexylmaleimide, N-methylmaleimide, N-ethylmaleimide, N-n-propylmaleimide, N-isopropylmaleimide, Nn-butylmaleimide, N-sec.
-Butyl maleimide, N-tert-butyl maleimide, N
-Octylmaleimide can be used, and these maleimide monomers have no coloring in the monomer itself, and the resin of the present invention obtained by using them also gives a molded product with little coloring. The use is not limited.

On the other hand, in addition to the above monomers, N-phenylmaleimide, No-methylphenylmaleimide, Nm-
Methylphenylmaleimide, Np-methylphenylmaleimide, N-o-toxoxyphenylmaleimide, Nm
-Methoxyphenylmaleimide, Np-methoxyphenylmaleimide, N-o-chlorophenylmaleimide,
Aromatic substituted maleimides such as Nm-chlorophenylmaleimide and Np-chlorophenylmaleimide can also be used. However, these aromatic-substituted maleimide compounds are colored yellow, and the copolymers obtained by using them are also colored yellow. You.

Further, among these maleimide compounds, N- is preferable as a preferable one in consideration of improvement in heat resistance.
Cyclohexylmaleimide, N-methylmaleimide, N
-Octyl maleimide, N-isopropyl maleimide and the like.

(B) The N-substituted maleimide compound is a monomer that bears heat resistance, and the higher the amount used, the higher the heat resistance.
Usually, it is desirable to use 1 to 80% by weight, preferably 1 to 49% by weight, more preferably 5 to 40% by weight, and most preferably 10 to 30% by weight. If it exceeds 80% by weight, the transparency of the obtained resin is impaired, the moldability of the resin is deteriorated, and the resin becomes extremely brittle, which is not preferable. If it is less than 1% by weight, sufficient heat resistance cannot be obtained.

(C) Styrene is copolymerized to improve the processability and heat resistance of the resin.
This is because the repeating structural unit composed of styrene and the (b) N-substituted maleimide compound is superior in heat resistance to the repeating structural unit composed of methyl methacrylate and the N-substituted maleimide compound. Therefore, the higher the amount of (c) styrene used, the more the heat resistance of the obtained resin tends to improve. However, if the amount of styrene used is too large, the obtained resin becomes a copolymer having a large composition distribution, resulting in decreased transparency and molding. It is not preferable because it may cause a decrease in sex and an increase in birefringence.
Usually, it is desirable to use 5 to 80% by weight, preferably 15 to 50% by weight, more preferably 16 to 45% by weight, and most preferably 16 to 35% by weight. When the amount used is less than 5% by weight, the heat resistance of the obtained resin is poor, which is not preferable.

Examples of the vinyl cyan compound (d) include acrylonitrile and methacrylonitrile.

Using these monomers, the strength of the resin obtained,
Since it can be expected to improve water resistance, chemical resistance, or transparency, it is used within the range of 0 to 20% by weight.

Methylstyrene dimer has the effect of a polymerization regulator, and its typical one is 2,4-diphenyl-4-methyl-1-pentene or 2,4-diphenyl-4-methyl-2-pentene. The amount of these used is 0.01 to 3 parts by weight, preferably 0.033 to 2.5 parts by weight, and more preferably 0.05 to 2 parts by weight, based on 100 parts by weight of the monomer to be polymerized. If the amount of the methylstyrene dimer used is less than 0.01 part by weight, the molecular weight of the copolymer resin obtained will be large and the moldability will deteriorate. Also, the amount used is 3
If the amount is more than parts by weight, the amount of the polymerization modifier is increased, the thermal stability and coloration of the resulting resin are decreased, and the molecular weight is decreased, so that the mechanical strength of the molded product is decreased. Is also not preferable.

Conventionally, as a polymerization regulator for adjusting the molecular weight of the polymer,
Mercaptan, m-thiocresol, thiophenol,
2-Ethylhexyl thioglycolate, β-naphthalenethiol, aldehyde and the like are common.

However, these polymerization regulators have a strong odor, and the obtained polymers have a certain degree of odor, and a odor that is generally called a dull odor is attached, which may cause a problem in practical use.

Further, it should be noted that in the present invention, N-like
In the production of a polymer containing a substituted maleimide compound as an essential component, a conventional polymerization regulator of the type in which chain transfer is carried out by hydrogen abstraction of thiol has a small effect of adjusting the molecular weight.

This is because the N-substituted maleimide and thiol such as mercaptan undergo Michael addition reaction and are consumed in reactions other than chain transfer, so that it is necessary to add a large amount of mercaptans, and the odor, coloring, and heat stability of the resin are required. This is because it causes a serious defect in sex.

On the other hand, the methylstyrene dimer used in the present invention is colorless and has a very slight aromatic odor. By using this N-substituted maleimide compound, its performance can be sufficiently brought out. It is of great significance to invent a transparent heat-resistant resin which has an effect as a molecular weight modifier, is free from odor and coloring, and has excellent thermal stability.

The polymerization method of each monomer of the present invention, emulsion polymerization, solution polymerization, bulk polymerization, suspension polymerization, bulk-bulk polymerization and other usual radical polymerization methods can be all applied, the following, the present invention In the following, the solution polymerization method, which is one of the preferable methods, will be described as an example.

As the polymerization solvent, a commonly used organic solvent such as toluene, benzene, methylethyl ketone, dimethylformamide, etc. can be used.

The polymerization initiator can be widely selected from ordinary radical polymerization catalysts such as organic peroxides and azo compounds. The amount of this polymerization initiator used depends on the intrinsic viscosity [η] of the copolymer.
If it exceeds 0.5 dl / g (30 ° C in methylethyltoken), the moldability is extremely reduced, so it is desirable to determine it in consideration of the amount of methylstyrene dimer used. Therefore, it is necessary to appropriately use the amount of the polymerization initiator in consideration of the amount of the methylstyrene dimer used so as to obtain a copolymer having an [η] value of 0.15 to 0.5 dl / g.

Further, various rubber-like polymers such as diene rubber and non-diene rubber can be present at the time of polymerization. From the viewpoint of transparency, it is preferable that the rubber-like polymer has a small particle diameter or has a refractive index substantially equal to that of the copolymer component.

As the polymerization method, a batch polymerization method in which all the monomers are charged all at once and polymerization is performed, an increment polymerization method in which a specific monomer, or a monomer mixture is continuously added to a polymerization system, a monomer There is a continuous polymerization method in which the mixture is continuously supplied to the polymerization system for polymerization and the obtained polymer is continuously taken out of the system.

However, it is desirable to select the polymerization method depending on the amount of styrene used. That is, since the copolymerization reaction between the N-substituted maleimide compound and styrene is strong in alternation and the polymerization rate is fast, the batch polymerization in a system containing a large amount of styrene results in a copolymerization reaction between the N-substituted maleimide compound and styrene. It occurs preferentially, and then the remaining monomer is polymerized into a reaction form, so that the repeating structural unit composed of styrene and the N-substituted maleimide compound increases in the composition distribution of the copolymer as the final product. As a result, the transparency of the resulting resin is decreased and the birefringence is increased. Therefore, in a system containing a large amount of styrene, it is preferable to employ an incremental polymerization method in which styrene is added little by little continuously or intermittently to the polymerization system of methyl methacrylate and an N-substituted maleimide compound.

As the method for molding the resin obtained by the present invention, injection molding, extrusion molding or the like can be used, and the molding temperature is 100 to 300 ° C, preferably 150 to 290.
C., more preferably 220 to 280.degree.

The resin obtained by the method of the present invention has excellent transparency, heat resistance and weather resistance, and is suitable for use in fields where the use of conventional transparent resins was unsuitable, for example, use in a high temperature environment. Is. Also, by mixing an appropriate amount of the resin of the present invention with a transparent impact-resistant resin such as transparent ABS resin and MBS resin, the heat resistance of the transparent ABS and MBS can be improved without significantly impairing the transparency thereof. Is possible.

e. Examples Next, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

Example 1 Toluene 3000 g, methyl methacrylate 3150 g, styrene 850 g, N in 10 autoclave equipped with stirrer and thermometer
-1000 g of cyclohexylmaleimide and 10 g of methylstyrene dimer (2,4-diphenyl-4-methyl-1-pentene) are charged and sufficiently stirred to form a uniform solution. After that, when the temperature rise is started and the internal temperature of the reactor reaches 100 ° C., a solution of 12.5 g of dicumyl peroxide dissolved in 500 g of toluene is added to start polymerization. Polymerization temperature is 120 ℃
The yield reaches 100% within 3 hours after the initiation of polymerization.

To remove the solvent and residual monomers, the obtained polymer solution is poured into water and steam is passed through it. The obtained solvent and the copolymer resin from which the monomers have been removed are pulverized and dried,
It was formed into pellets by an extruder with a cylinder temperature of 260 ° C.
A molded article obtained by injection molding from this copolymer pellet was measured for heat distortion temperature, optical characteristics and the like. The test results are shown in Table-3.

In addition, the long-term thermal stability shown in Fig.
Leave it in a gear oven at 0 ° C for a long time, measure the optical characteristics at each leaving time, and measure the yellowness (bL value) on the vertical axis.
The horizontal axis is expressed as elapsed time. In the figure, a low level of increase in yellowness with time indicates that the long-term thermal stability is good, and it is clear from the figure that the composition of the present invention is excellent.

Example 2 In the method shown in Example 1, various copolymer resins were obtained by changing the solvent, the catalyst, the re-composition of monomers, etc. as shown in Table 1. Table 3 shows the test results of molded articles obtained from the copolymer resin.

Comparative Example 1 With respect to the copolymer resin obtained according to the formulation shown in Table 2 without using methylstyrene dimer, the molded product was tested in the same manner as in Example, and the results are shown in Table 2.
3 shows.

The resin obtained by this comparative example is an example of polymerization without using methylstyrene dimer, and the resin has low fluidity and its molded product has a deep yellow tint.
As shown in the figure, the long-term thermal stability is poor.

Comparative Example 2 With respect to the copolymer resin obtained according to the formulation shown in Table-2, its molded article was tested in the same manner as in Example, and the results are shown in Table-3.

The copolymer resin obtained in this comparative example is an example in which the amount of methylstyrene dimer used exceeds the range of the present invention and is polymerized, and the polymerization yield of the copolymer is low and the heat resistance is poor.

Comparative Examples 3 and 4 A copolymer resin obtained by using a commonly used molecular weight modifier in place of methylstyrene dimer and following the formulation shown in Table 2 was molded in the same manner as in Example 1. The product was tested and the results are shown in Table-3.

As a result, in Comparative Examples 3 and 4, the obtained molded products had a strong yellow tint and were not preferable. The resin of Comparative Example 3 also has low fluidity.

Further, as shown in FIG. 1 for long-term thermal stability, it can be seen that the yellow discoloration is large in Comparative Examples 3 and 4.

Comparative Examples 5-7 According to the formulation shown in Table-2, each monomer was polymerized,
The copolymer resin obtained was molded and the molded product was tested. The results are shown in Table 3.

The copolymer resin obtained in Comparative Example 5 is an example in which the amount of methyl methacrylate used is less than the range of the present invention, and it can be seen that the birefringence is large and the optical characteristics are poor.

The copolymer resin obtained in Comparative Example 6 is an example in which the amount of N-cyclohexylmaleimide (N-substituted maleimide compound) used is less than the range of the present invention, and it is understood that the heat distortion temperature is low.

The copolymer resin obtained in Comparative Example 7 is an example in which the amount of styrene used is less than the range of the present invention, the fluidity is low, and the yellowish coloring is deep, which is not preferable.

f. Effect of the Invention The resin obtained by the present invention has a N-substituted maleimide compound newly added as a copolymerization component to improve heat resistance, and further uses methylstyrene dimer as a polymerization regulator as an essential component. Has significantly improved heat resistance and thermal stability without significantly impairing resin transparency, and is an excellent resin suitable for use under the severe conditions that have been increasingly demanded in the industry in recent years. It is a polymer.

Therefore, the method of the present invention provides a resin having excellent heat resistance, transparency, weather resistance, and thermal stability, so that the exterior and interior parts of automobiles, which are required to have heat resistance, and electrical / electronic related It provides molded parts such as parts and medical equipment, and has an extremely high industrial utility value.

[Brief description of drawings]

FIG. 1 is a diagram showing measurement results of long-term thermal stability of molded articles obtained in Example 1 of the present invention and Comparative Examples 1, 3 and 4.

Claims (2)

(57) [Claims] (A) Methyl methacrylate 10 to 90% by weight (b) N-substituted maleimide compound 1 to 80% by weight (c) Styrene 5 to 80% by weight and (d) Vinyl cyanide compound 0 to 20% by weight 100 parts by weight of the monomer consisting of
A method for producing a transparent heat-resistant resin, which comprises polymerizing in the presence of 0.01 to 3 parts by weight to adjust the intrinsic viscosity number of the copolymer to 0.15 to 0.5 dl / g. 2. The N-substituted maleimide compound is N-cyclohexylmaleimide, N-methylmaleimide, N-
Ethyl maleimide, N-n-propyl maleimide, N-
Isopropyl maleimide, Nn-butyl maleimide,
Claims (1) characterized in that it is at least one compound selected from the group consisting of N-sec-butylmaleimide, N-tert-butylmaleimide and N-octylmaleimide. How