DE1282292B - Use of a mixed polymer of methyl methacrylate and n-butyl acrylate or n-butyl methacrylate for the production of molded articles - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

B29c

German class: 39 a2-3 / 00

Number: 1282 292

File number: P 12 82 292.3-16 (J 23872)

Filing date: June 12, 1963

Open date: November 7, 1968

Polymethacrylic acid methyl ester is widely used in the manufacture of everyday objects, for example by injection molding or extrusion. Examples of such utensils, that can be made from this material are, for. B. phone housing, implosion protector for TV tubes, thermos flasks, fountain pens and light fittings. Utensils made from polymethacrylic acid methyl ester are manufactured, are currently in wide use and render very satisfactory service.

Polymethacrylic acid methyl ester is a particularly valuable product for the manufacture of everyday objects of this kind, as it is extremely transparent and firm and does not easily discolour in sunlight. When objects made of methyl polymethacrylate are brought into contact with certain liquids, however, the appearance of crazing may occur on the surface, with the surface covered with very fine lines. Some organic ao solvents and plasticizers as well as a repeated one Treatment with aqueous wetting agents or even warm water induce this phenomenon.

The invention is based on the object of eliminating these difficulties.

Accordingly, the invention relates to the use of a mixed polymer of methyl methacrylate and n-butyl acrylate or n-butyl methacrylate for producing molded articles by heating and pressing, the proportion of n-butyl acrylate or n * butyl methacrylate being 3 to 20 mol percent and 1.0 ° / o solution comprising of the copolymer in chloroform at 20 ° C has a specific viscosity of at least 0.60, a melt viscosity of at most 6 Kilopoises measured at 24O ⁰ C and a shear rate of 1120 sea-. ¹

It is important that the copolymers used have a specific viscosity of the aforementioned Order of magnitude so that the required resistance to crazing can be achieved can, and that they have a melt viscosity of the aforementioned order of magnitude, so that their flow properties are such that these copolymers are shaped in conventional devices can.

In general, comonomer contents of 5 to 15 mol percent are preferred in order to produce copolymers with good molding properties and good resistance to cracking. Increasing amounts of the So comonomer generally result in increased hairline cracking resistance and a reduction in the use of a copolymer
Methacrylic acid methyl ester and n-butyl acrylate
or n-butyl methacrylate for the preparation of
Molded articles

Applicant:

Imperial Chemical Industries Limited,

Millbank, London

Representative:

Dr.-Ing. H. Fincke, Dipl.-Ing. H. Bohr
and Dipl.-Ing. S. Staeger, patent attorneys,
8000 Munich 5, Müllerstr. 31

Named as inventor:

Brian Philip Griffin, Welwyn Garden City,

Hertfordshire (UK)

Claimed priority:
Great Britain January 3, 1963,

dated June 5, 1963 (425)

Melt viscosity at the expense of lower softening points in the finished molding,

The copolymers to be used according to the invention can be prepared by any known polymerization process are produced, provided that the process conditions are such that the value for the specific viscosity of the polymer is greater than 0.60. In general, polymers with higher Specific viscosity can be obtained by running the polymerization process at lower temperatures performs lower catalyst concentrations or lower amounts of polymerization modifiers or a combination of these measures. In polymerization processes, it is common to use molecular weight and thus the specific viscosity by adding known polymerization regulators, such as To control mercaptans, in particular lauryl mercaptan and tert-dodecyl mercaptan.

Antioxidants, heat stabilizers, lubricants, Pigments, light stabilizers and other auxiliaries are incorporated. These substances can, for. B. the Monomer can be added before the polymerization or the copolymer after the polymerization.

809 630/1007

The copolymers to be used according to the invention can be prepared by any conventional method. However, they are preferably produced by a bead polymerization process, since the product in this process is usually in the form of solid spherical particles with an average size of 50 to 500 μm. accrues ¹ and in an expedient. .Form is available for deformation. These particles can be separated from the aqueous phase by filtration or by centrifugation. After washing and drying, they can be used immediately for shaping. On the other hand, they can also be converted into granules, e.g. B. by extruding rods and then cutting the rods into short pieces. This process is useful when you want to process the powder with pigment into a pigmented molding compound.

Those produced by the process according to the invention Eorm powder or granules can be used to make a wide variety of objects will. Because of their particularly good resistance to hairline cracking when they are brought together

ίο with aqueous wetting agents such. B. for production used by wash basins.

The invention is further illustrated in the following examples. The values shown in the table below

- given numbers - relate to parts by weight.

'. For example

The following ingredients were placed in a vigorously stirred autoclave:

Dear

Desalinated water 100

Sodium polymethacrylate 0.03

Disodium hydrogen phosphate 0.3

Monomer Mix (given below) 100

Stearyl alcohol 1

tert-dodecyl mercaptan 0.4

Lauroyl peroxide 0.5

The stirred mixture was held at 80 ° C. until the monomer mixture was completely polymerized. This required 50 to 90 minutes depending on the particular monomers used. The mixture was then heated to 95 ° C. for 10 minutes and the suspension of the polymer particles cooled and spun off and dried. The dried particles were injection molded into a stick.

In this example two different Μόηο-mer-mixtures were used. In each case, the injection-molded rod was practically colorless and the polymers had a specific viscosity of at least 0.60, a melt viscosity of less than 6 kilopoises, measured at 240 ° C., and a shear rate of 1120 sec- ¹ . '■' ■. '
The injection molded bars were / immersed in a 1 ° _o aqueous solution of a polyethylene oxide-nonyl phenol condensate 24 hours at 65 ° C. The rods, removed from the solution, were then dried over silica gel for 24 hours, and the area of each sample on which haem formation occurred was determined.

The table below shows the monomer mixtures used. and the results for the Vicat softening point, the hairline crack area and the melt viscosity are given. The "results of a comparative experiment are also attached.

Monomer mixture

Dear

'Parts

Vicat softening point

Area with
Hairline cracking

Melt viscosity
Kilopoises

Specific

viscosity

in l%

Chloroform solution

90 n-butyl methacrylate

Commercially available polymethacrylate molding powder.:

102.1

110.0

16

90

3.0

0.90

0.5

Example 2

The following ingredients were placed in a vigorously stirred autoclave:

Dear

Desalinated water.;. 100

Sodium salt of a 1: 1 mixed polymer of maleic acid with ethylene 0.03

Sodium dihydrogen phosphate: 0.3.

Mixture of methacrylic acid methyl ester and acrylic acid butyl ester or meth-

butyl acrylate (given below), .. ''. ', ..!. i V 100

Lauroyl peroxide 0.4

tert-dodecyl mercaptan (given below) 0 to 1

The mixture was deoxygenated by evacuating the autoclave and filling it with pure nitrogen. After 80 minutes, heating to 80 ° C the temperature was raised 20 minutes 95 ° C, then the mixture with 0.5 part of 2,4-dimethyl-6-tert-butylphenol were added and cooled to 65 ⁰ C. After 10 minutes at 65 ^° C., the copolymer was cooled, spun off, dried and injection molded into strong, clear, hard rods which were essentially similar to polymethyl methacrylate in terms of strength, hardness and general appearance. The rods were subjected to the hairline crack test described in Example 1. The table below shows the compositions of the copolymers produced and the test results.

Monc
Methyl-
methacrylate
Parts mixed
Comonomer
Parts tert-dodecyl
mercaptan
Parts per 100 parts
Monomer % the area
with hairline cracking Specific
viscosity
in l%
Chloroform solution Melt viscosity
Kilopoises 94 Butyl acrylate
f. 0.15 1.9 1.77 4.2 94 Butyl acrylate
6th 0.17 0 1.75 4.4 92 Butyl acrylate
Q 0.22 2.3 1.34 3.7 92 Butyl acrylate
8th 0.11 0 2.03 4.4 88
88 Butyl methacrylate
12th
Butyl methacrylate
12th 0.14
0.085 3.0
0 1.12
2.05 3.6
5.2

Claims (1)

Claim: Use of a mixed polymer of methyl methacrylate and η-butyl acrylate or n-Butyl methacrylate for the manufacture of molded articles by heating and pressing, the proportion of n-butyl acrylate or n-butyl methacrylate Is 3 to 20 mole percent and one l, 0% by weight solution of the copolymer in chloroform at 2O ⁰ C a specific viscosity of at least 0.60, a melt viscosity of at most 6 Kilopoises, measured at 240 ⁰ C and a shear rate of 1120 lake having ^'1. Considered publications:
U.S. Patent No. 2,125,885. 809 630/1007 10.68 © Bundesdruckerei Berlin