DE1570855C3 - Process for the production of a graft copolymer - Google Patents

Description

These peroxides can be used individually or in the form of mixtures.

Details of the process for preparing the polymers are given below. In the Polymerization uses an emulsifying agent.

An aqueous dispersion of a butadiene polymer, the polymerization initiators, regulators and / or May contain latex stabilizers, methyl methacrylate is added with stirring, which is then mixed with the Butadiene polymer is polymerized. After the polymerization has practically ended, the aromatic vinyl compound added. The further polymerization is carried out in the presence of the formaldehyde sulfoxylate and the peroxide carried out.

After the end of the polymerization, the polymer is precipitated, filtered and dried.

If necessary, heat stabilizers, light stabilizers, processing aids, fillers, Dyes or pigments are added. The molding compound obtained in this way is then heated and deformed. The moldings obtained have excellent transparency as well as excellent Impact resistance on.

The polymers obtained in this way can mixed with polyvinyl chloride, chlorinated polyvinyl chloride or acrylonitrile-styrene copolymers molded articles having excellent impact resistance are obtained.

The most important conditions and effects of the process according to the invention are described below explained.

(1) An aqueous dispersion of a butadiene polymer must be used in which more than 80% of the particles have a diameter below Ο, ΐμ.

It is imperative to adhere to this condition if the desired transparency is to be achieved. If larger diameter particles are used, it can have excellent impact resistance can be obtained, but the transparency is then worse. In addition, the then also decreases Tensile strenght.

This fact is illustrated by Table I below. All parts and percentages indicated relate to weight.

Table I.

Relationship between the particle diameter of the butadiene polymer and the properties of the

obtained polymer product

attempt Ver according to equal invention attempt Percentage of particles of the butadiene polymer, the a diameter below 0.1 μ 99 9 Notched impact strength according to Charpy (cmk [/: m ² ) at 20 ° C 25.5 23.0 at -30 ° C 9.5 9.0 Tensile strength (kg / cm ² ) 360 320 Permeability visibility coefficient for visibility available light (V ₀ ) 79 45 Turbidity value (° / ₀ ) 5 26th

Remarks:

(a) An aqueous dispersion was used which contained 25% copolymer particles which consisted of 76.5% butadiene and 23.5% styrene (in the experiment according to the invention, a latex with a small particle size was used in an aqueous dispersion, while a latex with a large particle size was used in the comparative experiment). 3 parts of sodium formaldehyde sulfoxylate dihydrate and 1 part of cumene hydroperoxide were added to 25 parts of the copolymer, and stirring was continued at 60 ° C. for 1 hour.
To this emulsion: 40 parts of methyl methacrylate and 0.2 part of cumene hydroperoxide were added and polymerized continuously over a period of 2.5 hours; stirring was continued for an additional hour to complete the reaction after the additions were complete.

Then 35 parts of styrene and 0.2 part of cumene hydroperoxide were added and continuously polymerized over a period of 2 hours and finally stirring another Continued for one hour to complete the polymerization.

(b) All received. Polymer samples were kneaded on the roller for 10 minutes at 180 ° C and then compression-molded for 30 minutes at 190.degree.

(c) Test method:

Notched impact strength JIS K 6745

Tensile Strength, ASTM D 638-60T

Transparency JISK 6714V

(2) In the presence of formaldehyde sulfoxylate and of the peroxide, the monomers are added to the butadiene polymer for the purpose of graft polymerization.

(a) A mere addition of formaldehyde sulfoxylates to the aqueous dispersion of the butadiene polymer does not lead to any noticeable coagulation and enlargement of the butadiene polymer particles. However, the polymerization of methyl methacrylate in the presence of these materials will started, there is strong coagulation and enlargement of the dispersed particles instead, while a graft polymer is obtained at the same time.

(b) The formaldehyde sulfoxylate, together with the peroxide, promotes the crosslinking of the butadiene polymer.

These facts are illustrated by the following Table II.

Table II

55 attempt Comparison according to attempt present invention 6ο
Formaldehyde sulfoxylate not and peroxide admitted admitted Notched impact strength - according to Charpy (cmkg / cm ² ) 3.5 ⁵ at 20 ° C 25.5 3.0 at -? 0 ° C 9.5 370 Tensile strength (kg / cm ^s ) 360

Remarks:

An aqueous dispersion of the butadiene polymer used in the experiment according to Table I was obtained used, with 99% of the polymer particles had a diameter below 0.1 μ. The one in the Values given in Table II were made under the same experimental conditions as those obtained from Table I.

(3) When the slightly water-soluble methyl methacrylate is added to the dispersion for the purpose of polymerization is given and then - after the polymerization has practically ended - the water-insoluble aromatic vinyl compound is added and polymerized, products excellent in Impact resistance.

In contrast, when a mixture of methyl methacrylate and the vinyl aromatic monomer was used and the polymerization was carried out under otherwise identical conditions, moldings with good impact resistance could not be obtained. The desired impact strength was not obtained even if the aromatic vinyl monomer is first added and polymerized and only then was the methyl methacrylate added and polymerized.

ίο The effect of coagulation and enlargement of the Particles through the formaldehyde sulfoxylate and the peroxide are enlarged by first which adds water-soluble monomers. In this way, coagulation and graft polymerization proceed smoothly ahead. As a result, the impact resistance is improved as illustrated by Table III.

Table III

attempt
according to the invention Comparative experiment 1 Comparative experiment 2 Manner in which the monomers are added First adding the Adding one First adding the Methylmeth- Mixture of Styrenes, then acrylate, then Methyl meth of methyl meth- of styrene acrylate and styrene acrylate Charpy notched impact strength (cmkg / cm ² ) 20 ° C 25.5 11.5 10.8 -30 ° C 9.5 7.2 6.9 transparency Visible light transmission coefficient (%) 79 75 70 Turbidity value (%) 5.0 6.0 : 7.5

Remarks:

Except for the different methods of adding the monomers, these were the experimental conditions identical to those in Table I.

(4) Less than 60 parts of the butadiene polymer, 0.5 to 10 parts of the formaldehyde sulfoxylate, less than 3.0 parts of the peroxide and more than 40 parts of the monomers combined and are polymerized, the methyl methacrylate in an amount of 10 to 80% and the aromatic Vinyl monomers is used in an amount of 90 to 20% of the total amount of the monomers. Just using these amounts, the objects of the invention are achieved.

Exceeds when using the butadiene polymer and the monomers in a total amount from 100 parts to 60 parts of the butadiene polymer, tensile strength and Transparency of the product obtained. The required amounts of formaldehyde sulfoxylate and Peroxide vary depending on the polymerization conditions and the proportion of the monomers. However, as long as the stability of the dispersion is not adversely affected, it improves the impact resistance as the amount of these substances increases; the amount of peroxide is not so as decisive as the amount of formaldehyde sulfoxylate.

The formaldehyde sulfoxylate has no noticeable effect on coagulation and enlargement of the dispersed particles when used in an amount as low as 0.1 part per 100 parts of the monomers becomes, as is the case with ordinary emulsion polymerization. Is the percentage of methyl methacrylate below 10%, the end product obtained is bluish and opaque, while if the percentage of methyl methacrylate is over 80%, both the transparency as well as deteriorate the impact resistance.

B e i s ρ i e 1 1

In a polymerization vessel were placed 210 parts of an aqueous dispersion, 25 parts of a Copolymer of 76.5% butadiene and 23.5% styrene, with 99% of the copolymer particles had a diameter of less than 0.1 μ.

The dispersion was taking in the jar at 60 ° C

a stream of nitrogen and kept with a solution of 3 parts of sodium formaldehyde sulfoxylate dihydrate added in 15 parts of water and 1 part of cumene hydroperoxide. The mixture was then stirred for 1 hour and then with 40 parts of methyl methacrylate and 0.2 part of cumene hydroperoxide for the purpose of polymerization offset. Immediately prior to the addition of the methyl methacrylate, 98% of the particles had dispersed a diameter below 0.1 μ. Five hours later, the polymerization conversion was 93.5%. to the material obtained was a mixture of 35 parts of styrene and 0.2 part of cumene hydroperoxide given for further polymerization.

Five hours later, the polymerization conversion was 93%. At this point the polymerization was taking place canceled. An aqueous solution of hydrochloric acid and sodium chloride was used for coagulation added, after which it was filtered off and dried. In this way, there were 94 parts of a powdery Polymer obtained.

The product was processed on a roller kneading machine at 180 ° C. for 20 minutes and at

19O ⁰ C pressed. The following properties were measured on the test pieces obtained in this way.

Table IV

Tested property Measurement result Notched impact strength according to Charpy (cmkg / cm ² ) at 20 ° C 25.5 at -30 ° C 9.5 Tensile strength (kg / cm ² ) 360 transparency Permeability coefficient for sight available light (° / ₀ ) 79 Turbidity value (%) 5

methacrylate and 0.2 part cumene hydroperoxide were added.

Four hours later, the polymerization conversion was 95%. Then 30 parts of styrene and 0.2 parts of cumene hydroperoxide mixed together and added for the purpose of polymerization. 5 hours later the polymerization conversion was 94%.

With a similar further treatment as in Example 1, 96 parts of a pulverulent polymer were obtained ίο received.

This polymer was tested under the same conditions as in Example 1. It became the results given in Table V were obtained.

¹ S table V

The procedure used was the same as in the tests according to Table I.

Example 2

In a polymerization vessel in the same manner as in Example 1, 220 parts of an aqueous Dispersion containing 40 parts of polybutadiene particles, 92% of which had a diameter of less than 0.1 μm had a solution of 4 parts of sodium formaldehyde sulfoxylate dihydrate in 20 parts of water and 1 part Cumene hydroperoxide given. Then a mixture of 30 parts of methyl

Tested properties Measuring
Results Notched impact strength according to Charpy (cmkg / cm ² ) at 20 ° C 32.6 at -30 ° C 10.8 Tensile strength (kg / cm ² ) 295 transparency Permeability coefficient for sight available light (%) 75 Turbidity value (%) 7th

509 507/388

Claims (1)

1 2 It is also known (Ind. Eng. Chem. 1952, claim: _{Vol 44> s 778) Table III;} Section II, 1st line) that Process for the production of a graft mixture - a commercial latex of a composition, polymer by polymerization of at least as it is used according to the invention, a particle-40 parts of a monomer mixture of 10 to 5 size of. has only 0.08 μ.
80 percent by weight methyl methacrylate and 90 to the object of the invention was to provide a method for 20 weight percent of an aromatic vinyl preparation of a synthetic resin to develop the bond in an aqueous dispersion that has less both excellent impact resistance and 60 parts by weight of a butadiene polymer excellent transparency,
Contains, at least 50% of butadiene io The invention is a process for units, wherein more than 80% of the butadiene production of a graft copolymer by polymerizatteilchen have a diameter below polymerization of at least 40 parts of a mono-0.1 μ , as well as in the presence of a peroxide mixture of 10 to 80 percent by weight of Me-containing catalyst system, characterized in that methyl methacrylate and 90 to 20 percent by weight of an aromatic vinyl compound used in an aqueous system consisting of 0.5 to 10 percent by weight dispersion, which contains less than 60 parts by weight of a part of a formaldehyde sulfoxylate and less butadiene polymer, which consists of at least 50% than 3 parts by weight of a peroxide, and consists of butadiene units, with more than 80% that the methyl methacrylate is first polymerized butadiene polymer particles of a diameter and then the aromatic Have vinyl compound ao below 0.1 μ, as well as adding in the presence of one. Peroxide-containing catalyst system that thereby > is characterized in that one has a catalyst system used, which consists of 0.5 to 10 parts by weight of a (C. Synthetic resins made from polymers of monomers, formaldehyde sulfoxylate and. less than 3 weight as methyl methacrylate or vinyl aromatic compounds, have 25 parts of a peroxide, and that one first polymerizes the methyl methacrylate with its excellent properties and then adds the aromatic insulating properties, the resistance to vinyl compounds,
about chemicals and heat, transparency An important basic condition for transparency as well as processability. In addition, this leadership of the method according to the invention exists Synthetic resins having a low specific gravity and 30 in the particle size of the starting latex; to have to have low manufacturing costs, so that they have more than 80% of the butadiene polymer particles be used in a wide range of areas. Have a diameter of less than 0.1 μ. Through the Most of these synthetic resins, however, are post-use with the formaldehyde sulfoxylate / peroxide in common that they have a low impact strength on existing catalyst systems in larger quantities point, which limits their scope. 35 than usual is reached, Üass in addition to an acceleration Improvement of their impact strength, as opposed to polymerisation, is the crosslinking of the thimble joints Processes have been proposed in which chuke particles and an enlargement of the koagu rubbers Combined with these synthetic resins, the particle enters when the monomers are in the (cf. the published Japanese prescribed order to be added. Patent applications 1293/1953, 7538/1956, 2791/1958, 4 ° Finally, the gradual addition of the up-8136/1959 and 22 192/1964). grafting monomers in connection with the solid Although in many of these attempts considerable measures were taken to ensure that the impact strength improved the impact strength, and the transparency, surprisingly, failed to show that this could be improved at the expense of the. If one of the requirements transparency was omitted. With all these known methods, far worse results can be achieved,
therefore only masses could be obtained, butadiene polymers are polybutadiene and / which provided opaque moldings. or copolymers useful, the at least The German Auslegeschrift 1127 086 contains a 50% butadiene units, while the remainder consists of a process for the production of transparent to crystal clear units of an olefinic monomer, molding compounds with high impact and notched impact strength 50 which is copolymerizable with butadiene, e.g. B. Acrylic and good heat resistance through polymerinitrile, acrylic acid esters, methacrylic acid esters ^ aroma, sation of methacrylic acid methyl ester in the presence of vinyl compounds or chloroprene,
one to more than 50 percent by weight of butadiene as an aromatic. Vinyl compounds can and the remaining part of acrylonitrile composed of styrene, -methylstyrene, -ethylstyrene copolymer is known, in which together 55 or their nucleus-substituted derivatives, such as vinyl with methyl methacrylate, a comonomer mixed toluene, isopropenyltoluene or chlorostyrene is used, which is polymerized, among other things be aroma. These monomers are used individually or in tables vinyl compound, the co-form of mixtures used,
composition of the copolymer and the monomer As formaldehyde sulfoxylates are among others Rengemisches and the proportions between mixed 60 sodium formaldehyde sulfoxylate (NaSO ₂ CH ₂ OH-2H ₂ O) polymer and monomer mixture in a specific or zinc formaldehyde sulfoxylate [Zn (SO ₂ CH ₂ OH) ₂ ] way are regulated. In which way one besides the useful. These compounds are also found either individually or in the form of mixtures.
Can improve transparency, is the pre-published as peroxides are cumene hydroperoxide, diiso- not to be taken. It also gives 65 propylbenzene hydroperoxide, tert-butyl hydroperoxide, no teaching how to do with a given combination of di-tert-butyl peroxide, methyl ethyl ketone peroxide, leakage the desirable physical eigen- royl peroxide, benzoyl peroxide, ammonium persulphate, business can improve. Called sodium persulfate and hydrogen peroxide.