JPS6270412A - Manufacture of composition containing alkenyl aromatic monomer butadiene rubber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Solution polymerized butadiene polymers, such as polybutadiene and styrene-butadiene polymers, as well as rubbery butadiene polymers made using lithium-based catalysts, are suitable for many applications. It has already been recognized that it has extremely excellent physical properties11. Polymerization of butadiene polymers using lithium-based catalysts is described in U.S. Pat. No. 3,311.
, No. 918. One end use for such butadiene polymers is in the reinforcement of styrenic polymers and the production of impact resistant rubber reinforced molding and extrusion compositions, which are described in U.S. Pat.
No. 76.721.

Such butadiene polymers have been produced in a variety of ways. 1 to 12, lithium-based catalysts yield more preferred products for many purposes. Block polymerization of 1,3-butadiene is disclosed in U.S. Pat. No. 3,970,607, in which 1,2-diene is used as a reaction modifier to avoid excessive exotherm during polymerization.

Often such lithium-initiated or solution-polymerized rubbery butadiene polymers are available in solid or highly viscous liquid form. In the production of rubber-reinforced alkenyl aromatic polymers, such as polystyrene, they are dissolved in styrene monomers and the resulting rubber solution is then subjected to bulk polymerization techniques or bulk-suspension without dilution. Polymerization is performed using any of the polymerization techniques to obtain the desired *I sacrificial styrene polymer. The production of aromatic (alkenyl) monomer-rubber solutions requires considerable equipment, manpower, and time to obtain a homogeneous solution of the rubber in the 7-mer. The monomer-rubber solution is often filtered and then subjected to polymerization conditions.

It would be desirable to develop an improved process for making rubbery butadiene polymers, particularly as a solution using alkenyl aromatic monomers as solvents to avoid processing of undissolved rubber.

The present invention comprises (1) 80 to 30 parts by weight of alkenyl aromatic monomer, 20 to 70 parts by weight of butadiene (preferably 75 to 35 parts by weight of alkenyl aromatic monomer, 1 part by weight of butadiene) and substantially no polymerization under the polymerization conditions. Prepare a solution consisting of not more than 50% by weight of active solvent per total solution solution until 5 to 30% by weight of the total weight of the alkenyl aromatic monomer and butadiene is converted to the rubbery alkenyl aromatic monomer butadiene polymer. Polymerization is initiated using a lithium-based polymerization initiator, and ■ the polymerization is terminated and unreacted butadiene is separated therefrom; ■ the polymerization is then initiated to produce the desired amount of alkenyl aromatic monomer. polymerizing an alkenyl aromatic monomer with a comonomer such as acrylonitrile until the comonomer is converted to an alkenyl aromatic polymer;
Next, (2) the rubbery alkenyl aromatic monomer-butadiene polymer-reinforced alkenyl aromatic polymer is separated from the reaction mixture.

The alkenyl aromatic monomer has the formula where R1 is hydrogen or methyl, R,, R3, R4 are selected from hydrogen and an alkyl group having up to 10 carbon atoms, and RZ
s The total number of carbon atoms in R3 and R4 is 10 or less,
It is an alkenyl aromatic compound represented by Examples of such alkenyl aromatic monomers include styrene, vinyltoluene (all isomers and para isomers are more preferred),
α-methylstyrene, para-tertiary butyl-styrene, 3
．． 4-dimethylstyrene, 2-ethylhedylstyrene (all isomers), n-decylstyrene (all isomers) and n
-butyl-styrene.

The butadiene and alkyl aromatic monomers used in this invention should be substantially free of active hydrogen that would deactivate the lithium-based catalyst.

Lithium-based catalysts suitable for the practice of this invention are disclosed in U.S. Pat.
No. 317.918. Generally, n-butyllithium is preferred from the standpoint of availability and ease of handling.

The polymerization for the preparation of the rubbery alkenyl aromatic-butadiene polymers of the invention is preferably carried out at a temperature of 10°C to 70°C, more preferably 30°C to 50°C. This takes place in a vessel equipped with a stirrer, a heat transfer agent, and a condenser that allows reflux of the butadiene.

The basis of the polymerization according to the invention is that relatively low conversions of butadiene to rubbery polymers are tolerated. If most of the butadiene is offshore, the composite will not be rubbery due to the excess alkenyl aromatic monomer content. Also, if the conversion of butadiene exceeds about 30% of the electrolysis of butadiene, the potential for heat build-up and uncontrolled rapid polymerization of alkenyl aromatic monomers becomes very large. As the conversion rate of butadiene to polymer increases, the content of alkenyl aromatic monomers in the polymer increases as desired for reinforcement. Even ugly rubber loses its sexiness. From this point of view, in order to easily produce a polymer of good quality, it is necessary to terminate the polymerization at a conversion rate of 5 to 30 times the total amount of alkenyl aromatic monomer and butadiene.

Termination of lithium-induced polymerization is easily accomplished by addition of protonating compounds. Typical terminators include water, methyl alcohol, ethyl alcohol,
These include propyl alcohol, acetic acid, and propionic acid.

Once the anionic polymerization is terminated, unreacted butadiene is removed from the system by means such as vacuum or non-vacuum distillation. This butadiene can be easily condensed and recycled.

The butadiene rubber thus produced has a density of 30.0 per molecule.
00 to 700,000 molecules fl', and contains 1 to 40% by weight of copolymerized alkenyl aromatic monomers. Preferably, the rubber contains 2 to 25 1% by weight of alkenyl aromatic monomer, particularly preferably 5 to 15% by weight of styrene when used to reinforce a polystyrene or styrene polymer matrix.

After removing the butadiene, the free radical polymerization of the alkyl aromatic monomer can be initiated by the use of a conventional free radical initiator, such as a peroxy compound, an azo compound, or a combination of a peroxy compound and an azo compound.
However, free radical association is also thermally initiated.

Usually, free radical polymerization is carried out at a temperature of 60°C to 170°C. Free radical polymerization initiated by peroxy compounds is usually carried out at temperatures of 60°C to 170°C.

If initiated by heat, usually 110°C to 170°C
temperature ranges are used. It is preferred that at least the initial stage of polymerization of the alkyl aromatic monomer be agitated to obtain the desired impact resistant polymer. A preferred apparatus for such polymerization is disclosed in US Pat. No. 3,243,481.

Once the polymerization of the alkenyl aromatic monomer has taken place to the desired degree, the reaction mixture is heated to 180°C to 250°C under a pressure of 0°10 to 100 mT (f) to free as much of the surface as possible of the reaction mixture. Residual monomer is removed by exposure to a solvent chamber and cooling of the polymer.

Next, the present invention will be explained by reference examples and examples.

Reference Example A 1°1 t round bottom flask is equipped with a reflux condenser cooled with dry ice and a stirrer. Place the container under nitrogen atmosphere,
Add Japanese styrene 3182 and purified butadiene 170ft.

The contents of the flask were at room temperature (approximately 220°C). Polymerization was initiated by addition of 2-, a 0.523N solution of n-butyllithium in hexane. The polymerization temperature in the flask can be varied from about 14°C to 24°C by adjusting the reflux rate of butadiene.
It changed to ℃. 5 hours after addition of n-butyllithium, n-
The polymerization was terminated by adding about 0.2 vnl of bronochlor, and the 0 polymer was recovered by precipitation with methanol, yielding 45.59 g of a rubbery styrene-butadiene polymer. The yield was 9.3% by weight based on the initial weight of monomer.

Gel permeation chromatography was used for extramolecular determination and ultraviolet and refractive index detectors were used. The molecular weight was 187,000 per mole, and the polymer contained 14.9% styrene and 851% butadiene.

Styrene reaction ratio is 0.1, butadiene reaction ratio is 12
．． 5 and setting 17 Ha i eh and Glaze
(Rubber Chem, Tech,, 4
3.22.1970), the total amount of styrene was 14.5% and butadiene was 85.5%.
% will be included.

Example 1 A 2-t reactor equipped with a rotary stirrer was flushed with nitrogen, and 554 t of purified styrene and 677 tk of purified butadiene were charged.
．． Polymerization was initiated using 5-. The reaction mixture was heated to 45°C with dry ice placed in the -F section of the reactor to condense the butadiene.

The contents were kneaded at a temperature of 50°C, then crushed for 1 hour and 45 minutes with the addition of 1-7'rOn-butyllithium, and polymerized by adding 5rne of a 1N ethylbenzene solution of n-propano/l. It ended.

The reaction mixture had a solids content of 21.6 biphases.

The molecular weight of the polymer produced using the apparatus of Reference Example 1 was 322.000 per mole, and contained 68% by weight of styrene, with the remainder being butadiene.

The reaction mixture was then mixed with styrene 21 and excess butadiene monomer was removed by stirring the solution (and applying vacuum) to obtain a mixture consisting of styrene-butadiene rubber polymer 849 and styrene 10399.

(B) This mixture was further diluted with 228.4M styrene.

Add ethylbenzene 1502.1i12J]3 to this mixture.
．． 75P.

Stabilizer 2.25f, alpha methyl styrene dimer 1, available on the market under the trade name Irganox 1076
．． 05? and 32 of a 25% active solution of 1,1-di(tert-butylperoxy)-cyclohexane in ethylbenzene.

1200f of this mixture was added to a batch polymerization vessel equipped with a stirrer, and the temperature was raised from 110°C to 160°C over 7 o'clock rlfl.

After 4 hours, a further 200 t of Vr feed mixture was added. After 7 hours, the heating was stopped, and the mixture containing 72.1 weight and 1 inch of solid was placed in a shallow dish and heated to approximately 200°C in a vacuum oven for 9 hours.
) minutes were maintained.

The desolvated polymer was removed from the dish and ground 17. The samples were compressed into spheres for physical property measurements. The tensile strength of the polymer at its yield point is 2840 bonds/in2 (19.6 M
Pa), the tensile strength at break was 2965 bonds/in² and the elongation at break was 281 inches.

Notched Izot impact strength m゛ is 1.4 foot bond/
inch (75 J/m), and the Vicat heat distortion temperature was 212 below. These are typical properties of high impact polystyrene of similar rubber content.

Example 2 The method of Reference Example 1 was followed, but with a styrene-butadiene monomer ratio of 65:35 by weight, different amounts of toluene as diluent, and different starting temperatures, n-butyllithium concentrations, and polymerization times. Many different types of rubber were manufactured. The results are shown in Table 1.

Table 1 3 50 0.39 40 - 4 22 +1.76
23 385 22 0.54 23 45 6 0 0.77 16 25

Claims (3)

[Claims] (1) [1] Prepare a solution consisting of 80 to 30 parts by weight of alkenyl aromatic monomer, 20 to 70 parts by weight of butadiene, and 50% by weight or less of a solvent that is substantially inert under the polymerization conditions based on the total weight of the solution, [ 2] Conducting polymerization using a lithium-based polymerization initiator until 5 to 30% by weight of the total weight of alkenyl aromatic monomer and butadiene is converted into a rubbery alkenyl aromatic monomer-butadiene polymer;
[3] Terminating the polymerization and separating unreacted butadiene, [4
] A method for producing an alkenyl aromatic-butadiene rubber polymer-containing composition, which comprises carrying out free radical polymerization of unreacted alkenyl aromatic monomers. (2) The method according to claim 1, wherein the alkenyl aromatic monomer is styrene. (3) The method according to claim 2, wherein styrene is added before starting the free radical polymerization of styrene.