DE958251C - Process for the production of polymers and copolymers - Google Patents

Description

D 15094 IVb 139 ^c ISSUE ON FEBRUARY 14, 1957

LIBRARY

OF THE GERMAN

PATENT OFFICE

The invention relates to a method for regulating the molecular weight of alkenyl aromatic resins obtained by polymerizing one or more monovinyl aromatic compounds.
It is known that the physical and mechanical properties of the polymers and copolymers of monovinylaromatic compounds z. B. depend on the molecular weight of the polymer and that the molecular weight of the products can be lowered by increasing the temperature of the polymerization reaction or by carrying out the reaction in the presence of a solvent. But often it is undesirable to increase the polymerization temperature _t to obtain a product with lower molecular weight, as frequently occurs a considerable increase in the speed of the highly exothermic PoIymerisationsreaktion that an uncontrollable or "continuous" reaction or worse to form a product quality can lead. The dilution of the reaction mixture with a solvent often has the effect of reducing the rate of polymerization, which is undesirable. In most cases the amount of solvent

those used to reduce the molecular weight of the product by a greater amount, e.g. B. by half that of the product which, in the absence of the solvent, under otherwise identical polymerization conditions is required is quite large, so that the cost of producing a polymer increase significantly with the desired molecular weight.

It has now been found that the unsaturated ίο dimers of a monomeric α-methylstyrene of the general formula

ι Y

CH ₃ > - C = CH,

in which X and Y are hydrogen, halogens or lower alkyl radicals with not more than 3 carbon atoms and X and Y may be the same or different, in an unusual way as modifying agents for regulating the polymerization of monovinylaromatic compounds or mixtures a major portion of at least one monovinyl aromatic compound and 15 weight percent or less of a copolymerizable monoolefinic organic compound and polymers with a much lower average molecular weight than they produce under otherwise equal Polymerization conditions can be obtained in the absence of such an unsaturated dimer. By incorporating between 0.001 and 5 percent by weight lying amount of an unsaturated dimer of an α-methylstyrene of the above-mentioned Formula into a monomeric monovinyl aromatic compound or a liquid mixture of copolymerizable monoolefinic organic compounds containing at least 85 percent by weight of a containing monovinyl aromatic compound, and polymerizing the same in the usual manner forms a polymeric product, the majority of which in polymeric molecules are relatively close together Seems to have molecular weight. The effect of the unsaturated dimer of an α-methylstyrene of the above formula in reducing the average molecular weight of the resulting Polymerisats and in the modification of the polymerization reaction increases quite considerably with an increase in the amount of the unsaturated dimer in the starting materials from a trace, e.g. B. from 0.001%, up to ι percent by weight. A larger proportion of the unsaturated dimer causes another.

Reduction of the molecular weight of the polymer being formed; but this effect is all the less strong, the further the amount of unsaturated dimer from ι to 5 percent by weight of the polymerizable Components of the mixture is increased. Because of this, it becomes the unsaturated dimer or a mixture several dimers in an amount of 0.001 to 5 percent by weight of the polymerizable starting materials applied.

The polymerization regulators or modifiers with which the invention is concerned are the unsaturated ones Dimers of monomeric α-methylstyrenes. These unsaturated dimers can after in the U.S. Patent 2,429,719. Examples of monomeric a-methylstyrenes, from which the unsaturated dimers can be made are a-methylstyrene, p-methylstyrene, p-ethyl-a-methylstyrene, p-isopropyla-methylstyrene, m-ethyl-a-methylstyrene, m-methyla-methylstyrene, ar-dimethyl-a-methylstyrene, ar-chloromethylstyrene, 3, 4-dichloro-a-methylstyrene, ar-chloroar-methyl-a-methylstyrene, ar-diethyl-a-methylstyrene and ar-methyl-ar-isopropyl-a-methylstyrene.

It should be mentioned that the dimerization, i. H. Reaction of 2 molecules of a monomeric a-methylstyrene of the above general formula together, the olefinic product obtained is usually a mixture of isomeric unsaturated dimers, which is difficult to do in the usual way, e.g. by distillation is to be separated. So there is z. B. the unsaturated, obtained by dimerization of α-methylstyrene unsaturated 8g Product usually made from a mixture of the compounds 2,4-diphenyl-4-methyl-2-pentene and 2,4-D1-phenyl-4-methyl-i-pentene. The last-mentioned connection causes a far stronger one. Lowering the molecular weight of the z. B. by polymerization Polymer formed by styrene as an equal amount of 2,4 ~ diphenyl-4-methyl-2-pentene under otherwise same polymerization conditions. However, both isomeric unsaturated dimers of α-methylstyrene are effective polymerization modifiers for controlling the molecular weight of the polymerization an alkenyl aromatic compound obtained polymeric product, so that mixtures the isomeric unsaturated dimers can be used with success. The unsaturated dimers of the a-Methylstyrenes are usually applied in the form of a liquid mixture, which mainly consists of the corresponding isomeric derivatives of i-pentene and 2-pentene and a smaller part -15 percent by weight or less - the corresponding saturated or cyclic dimer of the monomeric α-methylstyrene consists; Of course, the unsaturated dimers can also be used alone in pure or practically pure form can be applied.

The unsaturated dimers of a-methylstyrenes or no Their mixtures can be used as modifiers or regulators for the polymerization of monovinylaromatic Compounds alone or in admixture with one or more other copolymerizable compounds unsaturated, a single olefinic, d. H. non-aromatic double bond in the molecule Connections are applied. This mixture of polymerizable components exists too at least 85 percent by weight of one or more monovinyl aromatic compounds. Examples suitable monovinylaromatic compounds are styrene, o-, m- and p-vinyltoluene, ar-chlorostyrene, p-chlorostyrene, ar-dichlorostyrene, m-ethylstyrene, p-isopropylstyrene, ar-dimethylstyrene or ar-ethylvinyltoluene or mixtures of two or more such monovinyl aromatic compounds. For the mixed

Polymerization of these monovinylaromatic compounds are suitable as further components which are copolymerizable Vinyl or vinylidene compounds, e.g. B. vinyl chloride, ethyl acrylate, methyl methacrylate, Vinyl acetate, methyl isopropenyl ketone, vinylidene chloride, acrylonitrile, α-methylstyrene or p-methyl-α-methylstyrene. The expression "monovinyl aromatic compound" here includes aromatic compounds understand the no more than io carbon atoms in

ίο contain the aromatic ring and only one Have a vinyl group attached to a carbon of the aromatic ring, e.g., styrene or vinyl naphthalene. In addition to the vinyl radical, the compounds can also contain up to 2 halogen atoms or lower alkyl radicals containing no more than 3 carbon atoms as core substituents.

Apart from the requirement that one or more of the unsaturated dimers of an α-methylstyrene must be present, the polymerization or copolymerization of the monomeric vinylaromatic Compounds can be carried out in the usual manner by e.g. B. in bulk in The presence of the unsaturated dimers or heated in an aqueous emulsion. Catalysts can be used for polymerization, e.g. B. benzoyl peroxide, acetylbenzoyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide or tert-butyl perbenzoate, advantageous in block polymerizations, d. H. practically in Absence of an inert liquid medium, can be used; however, the use of a catalyst is not mandatory. In the polymerization carried out in aqueous emulsion, usually catalysts, z. B. hydrogen peroxide or ammonium or. Potassium persulfate, especially at temperatures applied below 60 °. In the case where the polymerization is carried out in bulk, i. H. in Presence of the unsaturated dimer, but virtually in the absence of an inert liquid medium, will the polymerization reaction preferably at temperatures

temperatures between 80 and 150 °. The polymerization can be carried out in bulk at temperatures such as up to 90 percent by weight of the starting materials have been polymerized; then the mass is heated to higher temperatures, e.g. "- E.g. between 160 and 220 °, heated so that practically all remaining monomers are polymerized.

In practice, the unsaturated dimers of an α-methylstyrene, e.g. B. the dimers of a-methylstyrene ^ with the polymerizable starting materials in the desired ratio before carrying out the Polymerization mixed. Usually the unsaturated dimers are added before the polymerization ; but there are cases where a mixture of a high molecular weight polymer and the corresponding polymer having a relatively low molecular weight is desired; in such cases The unsaturated dimer of an α-methylstyrene can advantageously be added during the polymerization -will. The polymer product is usually obtained in a form that is suitable for immediate use suitable for the intended purpose; if necessary, one of the usual treatments must be carried out to get the shape you want.

So become ζ. B. if the polymerization has been carried out in bulk, the volatiles evaporated from the product by heating in vacuo, whereupon the product is cooled and by grinding or Cutting is brought into the appropriate shape. When the polymerization is carried out in aqueous emulsion has been, the product is in the usual way, e.g. B. by adding one of the numerous means capable of causing coagulation, e.g. B. of sodium chloride, hydrochloric acid or aluminum sulfate, precipitated, then separated from the aqueous liquor, washed and dried.

The following examples explain the principle of the invention without limiting it.

example 1

In one series of experiments, styrene was polymerized together with the unsaturated dimers of α-methylstyrene in amounts indicated in the following table quantities by heating in a sealed container according to the following time and temperature schedule: 4 days at 95 ⁰ and 2 days at 200 °. The dimers of α-methylstyrene used in the experiments were a liquid which boiled at 144 ° / 5 mm absolute pressure. The polymer was removed each time from the container and crushed into grains, go The flow rate at 135 °, expressed in seconds, required a sample of the polymeric product by 3.75 cm under a pressure of 70 atm through an opening of 3 mm diameter flow was determined by the method described in ASTM D 569-44T. The time required for this flow path became shorter with increasing flow speed. A portion of the polymer from each run was tested for percent volatile material; its viscosity was also determined. The determination of the amount of volatile material was carried out in such a way that a certain amount of the polymeric product was weighed, then ^{heated in vacuo at 2130 °} and 1 mm absolute pressure for 25 minutes, then cooled and reweighed. The weight loss gives the amount of volatiles. To determine the viscosity, enough of the polymeric product was dissolved in toluene that a weight percent solution of the same was formed, the absolute viscosity of which was determined in centipoises at 25 °. The viscosity is a relative measure of the average molecular weight of the resulting polymer. The viscosity decreases as the molecular weight of the polymer decreases. In Table I, each polymeric product is identified by the relative amounts (in percent by weight) of the styrene used in its manufacture and the unsaturated dimers of α-methylstyrene. The table gives further from any polymer, the percentages by weight of volatile material and to the absolute viscosity of a solution of the polymer iogewichtsprozentigen in toluene at 25 ° and the FHeßgeschwindigkeit at 135 ⁰ in seconds that a sample of the respective polymer, by 3.75 cm under at a pressure of 70 atm through an opening 3 mm in diameter.

Table I.

Styrene Raw materials Fleeting Properties of the Products attempt
No. in 7o in % 100 3.20 I. 99 3.07 2 97 2.98 3 95 2.42 4th Unsaturated dining
of a-methylstyrene viscosity Flow
speed in Vo at 25 ⁰ in seconds 0 l6l, 0 114 I. ΙΙ, Ο 66 3 3.7 30th 5 2.5 30th

Example 2

In a series of experiments, styrene was mixed with unsaturated dimers of 3, 4-dichloro-a-methylstyrene in the In the following table the quantities in one Containers enclosed and by heating according to the schedule and temperature given in Example 1 ^ polymerized. * In Table II, each polymer is identified in the manner shown in Table I- * draws.

Table II

Styrene Raw materials Fleeting Properties of the Products Flow
speed attempt
No. in ° / o in % Viscosity cP in seconds 100 0.66 at 25 ⁰ 270 I. 99 0.85 79.0 128 2 97 · 1.05 22.0 68 3 95 1.15 12.0 57 4th 8.0 Unsaturated dimers of
3,4-dichloro-α-methylstyrene in Vo O I. 3 5

Example 3

In a series of experiments, styrene was polymerized with unsaturated dimers of p-methyl-a-methylstyrene in the amounts given in the table below in a closed container according to the time and temperature conditions mentioned in Example 1. The unsaturated dimers of used in the experiments, p-methyl-a-methylstyrene represented a ^liquid-10 ° represents sigkeit, the mm boiled at 14,072th Part of each polymer was tested as described in Example 1. The results obtained are shown in Table III. The table also gives the% volatile content, the viscosity in centipoises ^<5 and the flow rate in seconds.

Table III

Styrene Raw materials Fleeting Properties of the Products Flowing
speed attempt
No. in % in % : P in seconds 100 0.77 284 I. 99 1.53 121 2 97 2.52 58 3 95 2.79 46 4th Unsaturated dimers of
p-methyl-α-methylstyrene Viscosity ( in ° / o at 25 ⁰ 0 2l6, O I. 40.0 3 12.8 5 7.1

In a similar series of experiments, the unsaturated dimers of ar-dimethyl-a-methylstyrene, those at 163 ° /! mm boiled as a polymerization modifier used in the proportions given in Table III. The results would be 135 practically the same.

Example 4

In one series of experiments o-chlorostyrene was polymerized with the unsaturated dimer of a-methylstyrene in amounts indicated in the following table quantities in a sealed container by heating 7 days on 40 °, 2 days at 95 ⁰ and 2 days at 150 °. The polymer removed from the container was crushed into grains. The polymers were tested in the manner described in Example 1. The unsaturated dimers of α-methylstyrene were a liquid that boiled at 12771.5 mm. Table IV identifies each polymer in the manner customary in the preceding tables.

attempt
No. Tabel Raw materials Unsaturated dimers
of a-methylstyrene IV Properties of the Products Flow
speed 10 o-chlorostyrene in Vo cP in seconds 15 ^τ in Vo O Fleeting 76 2 100 I. in Vo 57 3 99 3 5.6i 47 4th 97 5 5.78 37 95 6.1 6.84 viscosity at 25 ⁰ 9.0 7, o 7.0 7, o

Example 5

In a series of tests, 100 g of a mixture of styrene and the unsaturated dimers of α-methylstyrene were used in the amounts given in the following table in 140 g of an aqueous solution containing 1 g of trisodium phosphate, 3 g Aerosol MA (dihexyl ester of sodium sulfosuccinic acid), 3 g Dresinate (an alkali salt of rosin) and 0.7 g of potassium persulfate as a polymerization catalyst, emulsified. The at unsaturated dimers of a-methylstyrene used in these experiments were a liquid mixture, that of 38 percent by weight 2,4-diphenyl-4-methyli-pentene, 50 percent by weight 2,4-diphenyl-4-methyl-2-pentene and 12 percent by weight 1,1,3-trimethyl-3-phenylindane duration. Each mixture was heated to 60 ° with stirring for 6 hours. After that was the Emulsion coagulates. The polymeric product was filtered off, washed and dried. The viscosity of each polymer was determined by the method described in Example 1. Table V indicates each polymeric product by specifying the quantities of that used in its manufacture Styrene and the unsaturated dimer fraction. The viscosity of each polymer is also given. For comparison purposes, styrene was used under the same time and temperature conditions without the polymerized unsaturated dimers of α-methylstyrene.

Table V

Raw materials Unsaturated
Dimer fraction Products attempt
No. Styrene in Vo viscosity in % 0.0 UJT I. 100.0 0.75 3420 2 99.25 i, 5 217 3 98.5 2.5 41 4th 97.5 3.5 28 5 96.5 15th

Claims (4)

PATENT CLAIMS: i. Process for the production of polymers or copolymers from a monoolefini- see organic matter, the polymerizable part of which is at least 85 percent by weight at least a monovinyl aromatic compound having no more than 10 ring carbon atoms, thereby characterized in that the polymerization, based on the total polymerizable material, in the presence of 0.001 to 5 percent by weight of an unsaturated dimer of a monomer α-methylstyrene of the general formula CH, = CH, is carried out in which X and Y are hydrogen, halogen or a lower alkyl radical mean no more than 3 carbon atoms. 2. The method according to claim 1, characterized in that that the monoolefinic organic mass consists of a monovinylaromatic hydrocarbon, especially styrene, or a nucleus halogenated derivative thereof. 3. The method according to any one of the preceding claims, characterized in that the polymerization is carried out practically in the absence of an inert liquid medium. 4. The method according to any one of the preceding claims, characterized in that the polymerization is carried out in the presence of an unsaturated dimer of α-methylstyrene. Considered publications: German Patent Nos. 644 285, 813 457; Swiss Patent No. 287 881; U.S. Patent No. 2,533,525; German patent application M 6390 IVc / 39c (Patent 889 228); Fr. Krczil, Kurzes Handbuch der Polymerisierungstechnik, Vol. I, Einstoffpolymerisierung (1940), p. 263 f, also pp. 304 to 306. © 6ft9 579/534 8.56 (609 797 2.57)