JPS6028417A - Styrene-based heat-resistant and impact-resistant resin - Google Patents

Abstract

PURPOSE:To obtain the titled resin having unsaturated dicarboxylic acid anhydride group distributed non-uniformly on the graft-copolymerized side chain, by polymerizing an aromatic vinyl compound and an unsaturated dicarboxylic acid anhydride in the presence of a graft-polymerizable elastomer according to a specific method. CONSTITUTION:(A) 100pts.wt. of a monomer mixture composed mainly of (a) 55-98(wt)% aromatic vinyl compound (e.g. styrene) and (b) 2-45% unsaturated dicarboxylic acid anhydride (e.g. maleic anhydride) is graft-copolymerized in the presence of (B) 5-30pts.wt. of a graft-polymerizable elastomer (e.g. polybutadiene) by the following method. The component B is dissolved in a part of the necessary amount of the component A, the polymerization is started, the component (b) is added continuously in the former half period of the polymerization, the supply of the component (b) is stopped at the latter half stage of the polymerization to consume the component (b) in the system completely, and the polymerization reaction is continued.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a styrenic heat-resistant/impact-resistant resin comprising a copolymer whose main components are a vinyl aromatic compound grafted onto an elastomer and an unsaturated dicarboxylic acid anhydride. be.

That is, in the present invention, 5 to 30 parts by weight of a graft copolymerizable ethene to 100 parts by weight of a monomer mixture whose main components are 55 to 98 weight % of a vinyl aromatic compound and 2 to 45 weight % of an unsaturated dicarboxylic acid anhydride. In the method of producing a heat-resistant and impact-resistant resin by graft copolymerizing in the coexistence of parts by weight, an unsaturated dicarboxylic acid anhydride is continuously added to the polymerization system in the first half of the polymerization period, and in the second half of the polymerization period. By completely stopping the addition of the unsaturated dicarboxylic anhydride and allowing the polymerization reaction to continue even after completely consuming the unsaturated dicarboxylic anhydride monomer, the copolymerization chain of the side chain portion of the graft copolymer can be reduced. Styrenic heat resistant material has superior heat resistance compared to conventional technology by having unsaturated dicarboxylic acid anhydride distribution density in , relates to a method for producing impact-resistant resin.

General V styrene resins are widely used as plastic products because they are inexpensive, strong, lightweight, and have other convenient properties. However, in order to improve the low heat resistance, which is a drawback, a technique has been known in which the heat resistance is improved by copolymerizing an unsaturated dicarboxylic acid anhydride such as maleic anhydride. For example, Japanese Patent Publication No. 47-31118 and Japanese Patent Publication No. 54-19914 are examples.

Furthermore, in order to improve the brittleness of a styrene/maleic anhydride copolymer resin, a method of graft copolymerizing a rubber component to obtain a heat-resistant and impact-resistant resin is known from Japanese Patent Publication No. 7849/1983. This method shows alternating copolymerization even in a relatively small amount of maleic anhydride in the production of styrene/maleic anhydride copolymer, and has high copolymerization reactivity. This is a combination of the method of adding acid to the reaction system in continuous light to make the reaction uniform, and the rubber grafting method known for conventional high-impact styrene resins (rubber-grafted polystyrene) and ABS resins. .

However, according to the results of studies conducted by the present inventors, in this method, since a rubber component is added to impart impact resistance, the amount of maleic anhydride copolymerized is 10% in proportion to styrene.
If the amount is less than % by weight, the effect of improving heat resistance obtained by maleic anhydride copolymerization is considerably reduced. Furthermore, if the amount of copolymerized maleic anhydride exceeds 10 folds, the effect of improving the impact resistance due to the added rubber component is diminished. This fact is considered to be a natural conclusion even for those skilled in the art. Furthermore, the conventional technique of adding a small amount of maleic anhydride throughout the entire polymerization period is complicated, and adding a low-viscosity maleic anhydride monomer to a high-viscosity polymerization system in the latter half of the polymerization period is especially difficult for mixing. Other engineering problems remained. The present inventors studied this phenomenon in more detail and finally arrived at the novel invention.

According to the present invention, excellent heat resistance, which could not be obtained with conventional techniques, is achieved by providing a dense and dense distribution of unsaturated dicarboxylic acid anhydride in the copolymerization chain t of the side chain portion of the graft copolymer. This makes it possible to obtain impact-resistant resin.

Although the technical reasons for the effects of the present invention have not yet been fully clarified, taking the styrene/maleic anhydride copolymer as an example, the reason why the copolymer provides heat resistance is: Maleic anhydride with a closed ring structure is incorporated into the main chain of the molecule, and the main chain becomes rigid and free rotation around the main chain is loosened and restrained. Also, due to the polar effect of the styrene skeleton and maleic anhydride skeleton, a considerable amount of the molecule In view of the fact that thermal movement is restricted due to the free movement of molecules being constrained by gravity, the method of the present invention allows maleic anhydride to have a main chain structure in which it is partially arranged densely. It is thought that the above-mentioned factors (1) and (2) are further amplified by this.

According to the present invention, a block-like (non-cooperative with the maleic anhydride copolymerized portion) having a tapered (gradually changing maleic anhydride concentration) structure in which maleic anhydride is unevenly distributed. A main chain structure in which the main part and maleic anhydride are densely bonded (polymerized portions are bonded by chemical bonds) and a main chain in which maleic anhydride is bonded very sparsely (including polystyrene homopolymer) Structural parts are mixed independently in small amounts. Tape compatibilizes these and mutually exhibits the effect of improving the heat resistance of the main chain having dense maleic anhydride.
This is the role of the red structural part.

Generally, when two or more polymers with different properties are mechanically blended, it is extremely rare that they become finely compatibilized and the properties of the polymerized system are mutually improved; -IJ rubber and polyphenylene oxide/rubber grafted polystyrene are the only known cases.

However, in recent years, several examples have come to light in which combinations of two or more different properties that should originally exhibit compatibilization and exhibit a compatibilizing effect are caused by simultaneous polymerization reactions in the same system, such as 1. nterpenet- is also a simple example.

In fact, even in styrene/maleic anhydride copolymer,
In mechanical blending, according to the study results of the present inventors, a combination of different styrene/maleic anhydride copolymers with an average maleic anhydride copolymer composition of around 5% by weight is sufficient. Shows no compatibility.

Therefore, it is thought that the effect of the present invention is due to the fact that tapered structural elements can be obtained by simultaneous polymerization reactions in the same system.

Therefore, in a method in which unsaturated dicarboxylic acid is not added at all in the first half of the reaction and unsaturated dicarboxylic acid is added to the reaction system in the second half of the reaction, a mixed matrix resin that is not compatible with each other is produced. This results in a resin with significantly inferior properties such as heat resistance, and is therefore not within the scope of the present invention.

When carrying out the present invention, if the polymerization process is a batch operation, the required unsaturated dicarboxylic acid anhydride may be added continuously during the polymerization reaction only in the first half of the polymerization reaction, or may be added intermittently several times during the polymerization reaction period. A method such as dividing and adding water is adopted. In this case, when the addition of the unsaturated dicarboxylic anhydride is stopped in the latter half of the polymerization reaction, the unsaturated dicarboxylic anhydride monomer is completely absent from the polymerization system, and at least other vinyl aromatic compound monomers are present. It is necessary that one or more monomers be present in order for the polymerization reaction to proceed. In the case of continuous operation, the unsaturated dicarboxylic acid anhydride is continuously added to the polymerization tank at the latter stage of the process, and the unsaturated dicarboxylic acid anhydride is not added at all to the polymerization tank at the latter stage of the process. The method of the present invention can also be achieved depending on the situation. Of course, the method of the present invention is not limited to these examples.

Furthermore, in continuous operation, especially when the reaction tank is a piston-flow type, the amount of unsaturated dicarboxylic anhydride added to the reaction tank should be adjusted in consideration of the residence time of the polymerization solution (polymerization solution flow rate) and the copolymerization reaction rate. The method of the present invention can be achieved by adjusting one or more addition positions.

In this case, at least some zones in the reactor where unsaturated dicarboxylic anhydride is not added are completely devoid of unsaturated dicarboxylic anhydride and at least other vinyl aromatic heptamers are present. It is necessary for the polymerization reaction to proceed in the presence of one of the above polymers.

In this way, the present invention is a new technology that has been achieved as a result of careful study of technical problems that could not be solved with related prior art.

In the present invention, the vinyl aromatic monomer includes styrene,
Examples include α-methylstyrene, vinyltoluene, halostyrenes (eg, t+f o-chlorostyrene, P-chlorostyrene, etc.), and mixtures thereof.

Examples of unsaturated dicarboxylic anhydrides include maleic anhydride, chloromaleic anhydride, dichloromaleic anhydride, citraconic anhydride, itaconic anhydride, phenylmaleic anhydride, aconitic anhydride, and mixtures thereof. can give.

In the present invention, the quantitative ratio of the vinyl aromatic monomer to the unsaturated dicarboxylic acid anhydride is limited to a range of 55 to 98% by weight of the former and 2 to 45% by weight of the latter. If the amount of unsaturated dicarboxylic anhydride is less than 2% by weight, a sufficient effect of improving thermal properties cannot be expected. If the amount exceeds 45% by weight, the resulting copolymer will be insoluble in the polymerization system and will precipitate, making it impossible to carry out homogeneous polymerization, lowering the molecular weight, significantly lowering water resistance, and poor melt fluidity. This is inconvenient because it has many drawbacks as a Planutinox product.

The graft polymerizable elanuttomer according to the present invention is used in an amount of 5 to 30 parts by weight based on 100 parts by weight of the monomer mixture.

If it is less than 5 parts by weight, a sufficient effect of improving impact resistance cannot be expected, and if it is more than 30 parts by weight, the resulting resin becomes too flexible and a sufficient effect of improving heat resistance cannot be expected, and at the same time polymerization This is not preferable because the system becomes too viscous and does not exhibit adequate miscibility.

Types of graft-polymerizable elastomers include all elastomers that can be graft-polymerized with vinyl and have hydrogen, unsaturated bonds, etc. Examples include polybutadiene (mainly composed of cis-1,4 bonds), syndiotactic Chic-1,2-polygetadiene, styrene-butadiene random copolymer, SBS or SB type styrene-butadiene block copolymer or partially hydrogenated product thereof,
Elastomers such as EPDM copolymerized with nitrile rubber, maleated rubber, polyisoprene, polychloroprene, liquid polygetadiene with functional terminals, acrylic rubber containing unsaturated groups, norbornadiene or cyclopentadiene, ABS, MBS, and high impact properties. Examples include rubber graft resins such as styrene resins.

In addition, antioxidants, ultraviolet absorbers, lubricants,
Additives such as plasticizers and colorants can be added as appropriate before, during or after polymerization.

The resin material obtained by the method of the present invention has impact resistance, #
Because it has excellent heat resistance, moldability, and other properties required for practical use, it can be advantageously used as a material for producing plastic molded products by injection molding, extrusion molding, and other heat shaping methods. can be done.

The present invention will be explained below with reference to Examples.

Example 1 4 made of 5US304 equipped with a stirring device with double helical ribbon blades, a raw material inlet with two cooling tubes, a polymerization temperature detection device, a heating rack, a sampling valve, etc. on the top and bottom.
Styrene monomer 10.6 at room temperature in OL rigid polymerization apparatus
A9 was charged, and granular maleic anhydride 1802 was added and dissolved under stirring. Then, cut into strips
1,4-polygetadiene (Diene NF35A manufactured by Asahi Kasei)
S, number average molecular weight 107.500) 1.2 ky was gradually added with stirring and completely dissolved over a sufficient period of time.

Thereafter, the polymerization apparatus was purged with nitrogen and the temperature was raised to 120C to start the graft polymerization reaction. After 10 minutes, a solution of 5ooy maleic anhydride dissolved in styrene L4Ay was added to 70%
It was added quantitatively to the polymerization system over several minutes. After the addition of maleic anhydride was completed, polymerization was continued for about 6 hours, and a sample of the polymerization mixture was taken and analyzed to find that the solid content was 564%, and therefore the polymerization rate was 520%. η of ungrafted styrene-maleic anhydride copolymer? The maleic anhydride content in 6S was 95%. The polymerization mixture is then heated to 240
The monomer was degassed by feeding it into a flash type vacuum thin film evaporator for about 20 minutes at ℃. The resulting pellet contained about 790 ppm of styrene monomer and no maleic anhydride monomer was detected. The obtained pellet was subjected to solvent fractionation and the gel fraction was taken out and found to be 254%. When a transmission electron micrograph was taken, dispersed rubber particles having a stable salami structure were observed.

In addition, a physical property evaluation sample was prepared from the PVC and measured, and the thermal deformation temperature was 107'C and the Izot impact strength was 9.
5 kq・(1)/(7): Breaking strength 340/, qfi
d, elongation at break was 26%.

Comparative Example 1 In the same apparatus as in Example 1, 10.2 kq of styrene, polygetadiene L 2 #, and 721 units of maleic anhydride were charged and the temperature was raised to 120°C. After raising the temperature for 10 minutes, a solution of 624-maleic anhydride dissolved in 1.8 kq of styrene was continuously added quantitatively for about 6 hours until the polymerization reaction was completed. The sample obtained by vacuum monomer degassing had an apparent polymerization rate of 482%, an ungrafted styrene-maleic anhydride copolymer η811/C = 0.88, a maleic anhydride content of 8.4%, and a gel content. The rate was 263%.

The physical properties are lower than those of Example 1, with a heat distortion temperature of 98'C notched Izotization impact strength of 8. OkQ-an/am,
It has a breaking strength of 3201g/c4 and a breaking elongation of 25%.

Comparative Example 2 In the same equipment as in Example 1, 841 g of styrene and 0.0 g of borosilicate were added. After charging '84Ap and raising the temperature to 90'C, lauroyl peroxide 56.42 styrene 11 kr
The solution dissolved in i was continuously added quantitatively for about 25 hours.

After the addition of lauroyl peroxide, the temperature was raised to 120°C, and immediately after the temperature was raised, maleic anhydride 6802 was added to styrene 2,
A solution dissolved in 5 kq was continuously added quantitatively for about 15 hours. Apparent polymerization rate of sample obtained by vacuum monomer degassing 495%, ηs p/C-0.60 of ungrafted styrene-maleic anhydride copolymer, maleic anhydride content 9.4% gel fraction It was 24.8%. As for the physical properties, the heat distortion temperature is 90 Ic, which is considerably lower than that of Example 1, and the notched IZO impact strength is 8. Oky・−/−,
It had a breaking strength of 200 h/cd and a breaking elongation of 25%.

Example 2 In Fig. 1, prepolymerization tank 1 has a 5L three-stage V-blade stirring device as the first tank, and polymerization tank 2 has a 5L double helical ribbon blade mixing device as the second tank. ,
Vacuum thin film evaporators 3 having a heat transfer area of 0.2 m' are connected to each other by polymer transport pipes via gear pumps. A1, B, the injection point of each component into the first tank and the second tank, C, C,, C, the polymer flow of each polymer transport pipe, 4 the recovered monomer outlet, 5 the This is the product outlet. Based on the process flow shown in FIG. 1, continuous polymerization was carried out according to the material balance shown in Table 1.

That is, the first tank was set at 120°C, and maleic anhydride was dissolved in styrene as 79. As B, a predetermined amount of a styrene solution of polybutadiene was continuously injected. The polymer flow C1 is set by the gap pump at flow i 14.58 # 7 hours, and the hold amount of the first tank is 87.7
kv, the average residence time was 602 hours, the polymerization yield was 325%, and the maleic anhydride copolymerization rate was 130%.

The second tank was set at 120° C., and the polymerization reaction was continued without using B2. The holding amount of the second tank was 137 kq, the average residence time was 9.38 hours, the polymer flow C7 was 14.58 passes/hour, and the polymerization yield was 626%. The operating conditions of the monomer devolatilization device 3 were 240° C. and a degree of vacuum of 2t 01v, and the residual styrene monomer in the obtained graft copolymer was 490 ppm.

The obtained sample contained 10.0 parts by weight of rubber, had a maleic anhydride content of 8.0%, and had a notched Izot impact strength of 9.
．． 8#.(7)7mm, heat deformation temperature: 105°C, breaking strength: 405 ng/ci, and breaking elongation: 95%.

Comparative Example 3 An experiment similar to that in Example 2 was attempted, except that the maleic anhydride/styrene solution was injected in several parts. Rubber content la of the obtained graft copolymer
o weight tr% maleic anhydride content 80%, notched Izot impact strength 6.5 jp・ψ, slightly lower than Example 2, heat distortion temperature 99' (, breaking strength 4101; 9/c
d, elongation at break was 75%.

Table 1 Material balance of continuous graft polymerization be.

1.2...Polymerization tank 3- Monomer devolatilization equipment

Claims (1)

[Claims] Graph!・In the method of producing a heat-resistant and impact-resistant resin by graft copolymerizing in the coexistence of 5 to 30 parts by weight of a polymerizable elastomer, in the first half of the polymerization period, an unsaturated dicarboxylic anhydride is continuously added to the polymerization system. In the latter half of the polymerization period, the addition of the unsaturated dicarboxylic anhydride is completely stopped and the polymerization reaction is continued even after the unsaturated dicarboxylic anhydride monomer is completely consumed. A method for producing a styrene-based heat-resistant and impact-resistant resin, which is characterized in that the copolymerization chain of the side chain portion of the polymer has a dense and dense distribution of unsaturated dicarboxylic acid anhydride.