DE1197226B - Molding compounds made from polypropylene and ethylene copolymers - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C08f

German class: 39 b -22/06

Number: 1197226

File number: S 74738IV c / 39 b

Filing date: July 8, 1961

Opening day: July 22, 1965

Polypropylene is a relatively rigid thermoplastic synthetic resin, which is characterized by its high Tensile strength, high elasticity and elongation and relatively low density. Molding compounds made of polypropylene are therefore of great technical importance. An important property is for many plastic products their impact resistance low temperatures. Polypropylene is sufficient for many technical uses Low-temperature shock resistance, however, only if it has a relatively high molecular weight and therefore has a correspondingly low melt index. But only then can plastics be satisfactory deform by injection molding if their melt index is not significantly lower than 0.5. At the Polypropylene has an unfavorable relationship between melt index and low temperature shock resistance because of this Plastic only exhibits satisfactory low-temperature shock resistance if its molecular weight is so high that the melt index is substantially below 0.5, while polypropylene with a Melt index above 0.5 no longer has adequate low-temperature shock resistance. It follows that Plastic products of good low-temperature shock resistance made of polypropylene by injection molding do not can be produced.

Attempts have been made to remedy this drawback by producing plastic mixtures from polypropylene and copolymers of propylene and ethylene to remedy (Belgian patent 582153). These Mixtures consist of 30 to 90 percent by weight of polypropylene and 10 to 70 percent by weight a propylene-ethylene copolymer with a propylene content of 3 to 20 percent by weight. Around but in this way to get plastic mixtures with sufficient low-temperature shock resistance, a polypropylene with an extremely low melt index must be used as the component of the mixture of 0.03, and even mixtures that are only 30 percent by weight of this polypropylene and 70 percent by weight of a propylene-ethylene copolymer with an ethylene content of 90% have, despite their good low-temperature shock resistance only a melt index of 0.41, which is still not high enough for processing by injection molding.

It has now been found that molding compositions can be obtained which meet the requirements for good processability injection molding and good low-temperature shock resistance suffice when using polypropylene Copolymers of ethylene and acrylic or methacrylic acid alkyl esters mixed.

Molding compounds made from polypropylene and ethylene copolymers

Applicant:

Spencer Chemical Company,

Kansas City, Mo. (V. St. A.)

Representative:

Dr. W. Kühl, patent attorney,

Hamburg 36, Esplanade 36 a

Named as inventor:

George Edloe Ham, Leawood, Kan .;

William Highfill Byler, Orange, Tex. (V. St. A.);

Sylvester Peter Horkowitz, Tokyo

Claimed priority:

V. St. v. America July 12, 1960 (42 217) - -

The molding compositions according to the invention made from propylene and ethylene copolymers contain as copolymers 5 to 50 percent by weight, based on the total mass, of a copolymer of ethylene and an acrylic or methacrylic acid alkyl ester with up to 60 percent by weight of acrylic or methacrylic acid ester units.

There are already molding compositions based on polyethylene known which are a copolymer

of ethylene and a low molecular weight acrylic acid alkyl ester with a content of bound acrylic acid alkyl ester of about 2 to 25 percent by weight in amounts of 20 to 80% of ^the total weight of the molding compound (interpreted documents of Belgian patent 579 533). In these known polyethylene molding compounds, the addition of the copolymer of ethylene and the acrylic acid alkyl ester is not used to improve the low-temperature shock resistance, because polyethylene is inherently flexible and still has sufficient elasticity even at very low temperatures. The purpose of the addition in this case is rather that of the molding compounds

509 627/354

On the basis of polyethylene, the tendency to develop internal stresses during processing at high temperatures, e.g. B. in casting or extrusion to take, which often lead to cracking or to break the polyethylene products under stress, e.g. B. when bending, has led.

However, it was not foreseeable that the addition of copolymers of ethylene and acrylic acid or methacrylic acid alkyl esters for the purposes of the invention to form molding compositions based on polypropylene Impact resistance at low temperatures would improve significantly and that one in this way to polypropylene molding compounds which, in contrast to molding compounds based on polyethylene, would have the typical rigidity and tensile strength of polypropylene and yet have a sufficiently high melt index for deformation.

A favorable concentration of the copolymer in the molding compound is in the range of approximately 15 to 35 percent by weight, while a concentration of copolymer in the range from 20 to 30 percent by weight is particularly preferred.

The products made from these molding compositions have a clear appearance.

Polypropylenes with various molecular weights which are solid at normal temperature are suitable as the polypropylene component of the molding compositions according to the invention. Preferably, the polypropylene used as a blend component has a melt index of 3.5 to 6 at 250 ⁰ C, and preferably to use isotactic polypropylene, ie one in which the isotactic content of 90 ° / ₀ or more.

Copolymers of ethylene with acrylic acid or methacrylic acid alkyl esters are used as the copolymer component, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, 2-ethylhexyl, decyl, lauryl or stearyl esters, in Consideration. Of these, copolymers of ethylene and methyl acrylate are preferred. the Copolymers contain 4 to 60 percent by weight of acrylic acid ester units and preferably contain 6 to 30 percent by weight, in particular about 15 to 25 percent by weight of acrylic acid ester units, with Of course, the molecular weight of the respective acrylic acid alkyl ester has to be taken into account. Suitable Copolymers are those in which the acrylic acid alkyl ester units are distributed to a high degree uniformly in the copolymer chain. The production these copolymers are preferably carried out in accordance with British patent specification 900,969.

The mixing of the polypropylene with the copolymer can be carried out in a known manner, for. B. you can thoroughly mix cubes made of polypropylene with cubes made of the mixed polymer and that Then knead the mixture thoroughly in a Banbury mixer or preferably in a mixer extruder to process.

Various customary additives, such as dyes, Pigments, stabilizers, lubricants, ultraviolet protectants and anti-stick agents are added will.

The molding compositions according to the invention are used for the production of a wide variety of objects as well of fibers, films and pipes use.

In the following examples, the low temperature shock resistance determined by producing flat peelings from the molding compounds by injection molding became. These bowls were placed upside down and weights were dropped in the middle of the floor calmly. Each test was carried out on twenty cups, and as impact resistance on the one in question That force is given in cm · kg that was required to reduce the temperature by half that of the temperature Destroying shells subjected to testing.

The acrylic acid ester content of the copolymers given below is determined by ultra-red analysis certainly.

According to the method of British patent specification 900 969, for. B. the following copolymers manufactured:

Table I.

Ester Ester Ethylene Enamel
index density Softening point Mixed
polymer Acrylic acid methyl ester Weight
percent Weight
percent 1.72 0.9365 after Vi cat
⁰ C A. Acrylic acid methyl ester 15th 85 1.81 0.9447 71 B. Acrylic acid methyl ester 25th 75 0.34 0.9443 47 C. Methacrylic acid methyl ester 25th 75 0.55 0.9274 52 D. Butyl methacrylate 5.3 94.7 4.45 0.9219 70.5 E. Methacrylic acid methyl ester 8.9 91.1 52 F. Methacrylic acid hexyl ester 9.4 90.6 G Stearyl acrylate 9.2 90.8 H Butyl acrylate 16 84 2.87 0.9210 I. 4.2 95.8 75.8

example 1

From polypropylene a content of isotactic polymer mk of 90 ° / ₀ and a melt index at 250 ⁰ C of 3.5 and the copolymers given above were prepared molding compositions. The two components were mixed together in the form of cubes and the mixtures were processed into uniform masses in either a Banbury mixer or a mixer extruder. The mixing in the Banbury mixer was 2 to 5 minutes at 177 ° C, while the use of the mixing extruder the mix had a temperature of about 185-260 ⁰ C. The molding compositions obtained in this way were tested for their low-temperature impact resistance using the method described above, with the following results:

Table II

Molding compound no.

2 3 4th 5 6th 80 75 65 90 75 A. B. B. C. C. 20th 25th 35 10 25th 142.2 135.5 98.3 49.7 154.6 85.6 80.0 107.5 11.0 88.4

Polypropylene, parts by weight

Mixed polymer

Parts by weight

Shock resistance at -15 ° C, cm-kg Impact resistance at -25 ° C, cm · kg

85 A 15 71.7 13.8 80
D.
20th
82.8 26.2

10

Molding compound no.
11 I.

12th

13th

Polypropylene, parts by weight

Mixed polymer

Parts by weight

Impact resistance at -15 ° C, cm · kg Impact resistance at -25 ° C, cm · kg

75 75 65 75 75 E. F. F. G H 25th 25th 35 25th 25th 140.8 135.5 98.3 134.0 140.8 81.4 83.3 107.5 77.3 82.8

70 D 30

163.0 91.1

Example 2

75
I.

25th

138.0 80.0

The nature of the mixture components,

further molding compounds made of polypropylene and mixed- the composition of the molding compounds and their

Polymers of ethylene and methyl acrylate low-temperature impact strengths are as follows

ester or methacrylic acid methyl ester. See table:

Table III

Polypropylene lot
Weight lot
Weight Ethylene Mixed polymer Methacrylic acid
methyl ester Enamel Tem Push Molding compound Art percent percent 7o Acrylic acid
methyl ester % index temperature strength 80 20th 80 7o 2.0 ⁰ C cm-kg 15th (1) 80 20th 80 20th - ■ 2.0 -15 78.8 (D 75 25th 80 20th - 2.0 -25 60.8 16 (D 75 25th 80 20th 2.0 -15 134.1 (D 70 30th 80 20th - 2.0 -25 113.4 17th (1) 70 30th 80 20th - 2.0 -15 125.8 (D 80 20th 80 20th 20th 2.0 -25 112.0 18th (1) 80 20th 80 - 20th 2.0 -15 37.3 (1) 80 20th 80 - 2.0 -25 11.1 19th (2) 80 20th 80 20th 2.0 -15 18.0 20th (3) 80 20th 80 20th - 2.0 -15 152.1 (3) 80 20th 85 20th - 2.0 -25 11.1 21 (1) 70 30th 85 15th - 2.0 -15 69.1 22nd (1) - - 15th - 8.0 -15 110.6 control (1) - - - - 0.5 0 <5.5 control (2) - - - - - 0.5 0 <5.5 control (3) - 0 <5.5

The three types of polypropylene used in the above experiments were

(1) a commercially available polypropylene with a melt index of 8.0,

(2) a test-made polypropylene with a melt index of 0.5,

(3) a commercially available polypropylene with a melt index of 0.5.

The numerical values show that polypropylene with a relatively high melt index was used in all cases and that the melt indexes of the mixtures (since the copolymers all have a melt index of 2.0) are considerably above 0.5. It can also be seen from this that the copolymers to be used according to the invention as a mixture component in all cases increase the impact resistance of the polypropylene very considerably at low temperatures. While the impact strengths of the pure polypropylene types are already ^{below 5.5 cm · kg at 0} ° C., which is completely inadequate, the mixtures achieve significantly higher impact strengths at -15 ° C and mostly also at -25 ° C.

Claims (1)

Claim: Molding compounds made of polypropylene and ethylene copolymers, containing as copolymer 5 to 50 percent by weight, based on the Total mass, a copolymer of ethylene and an acrylic or methacrylic acid alkyl ester with 4 to 60 percent by weight acrylic or methacrylic acid ester units. Considered publications:
Open documents of Belgian patents nos. 153, 579 533. 509 627ß54 7.65 © Bundesdruckerei Berlin