CS235533B2 - Anti-locking mixture on base of ethylene homopolymer or ethylene copolymer - Google Patents

Description

The invention relates to an anti-blocking composition based on an ethylene copolymer or an ethylene copolymer with at least one comonomer selected from the group consisting of vinyl esters of carboxylic acid, such as vinyl acetate, carbon monoxide, maleic acid hydride, alkyl acrylates. and alkyl methacrylates having an alkyl group having 1 to 6 carbon atoms and olefins having 3 to 8 carbon atoms. This mixture is suitable for the production of films.

The films of ethylene polymer are characterized by poor sliding properties which impede their use in automatic processing machines. They also exhibit a tendency to resist tearing apart as a result of the adhesion force that prevents malposition with them. The sliding and cutting forces of such films having a perpendicular direction to each other are closely bound to each other and cause numerous problems in the industrial use of polyethylene films.

To improve their use, it is known to add a glidant and an anti-blocking agent to the ethylene polymer prior to extrusion. For example, British Patent Specification No. 822,498 discloses polyethylene-based compositions containing an inert filler in an amount of 0.1 to 5% by weight with a particle size in the range of 0.02 to 50 µm. French Patent Specification No. 1 204 623 describes branched polyethylene based compositions containing a stearic oxygen-stabilizing product in an amount of up to 0.5% by weight, having a grain size below 1 µm. French Patent Specification No. 1,235-862 discloses a base-based formulation. polyethylene, isopropanol. silicon dioxide having a particle size in the range of 1 to 10 µm in a weight range of 0.10 to 1.5% ·

The purpose of the invention is to improve the properties, in particular the optical, blocking salt, based on an ethylene homopolymer or an ethylene copolymer and thus also on films made therefrom by simply selecting a certain anti-blocking agent. In pursuing this purpose, the choice of talc fell as a preferred blocking agent.

Accordingly, the present invention provides an anti-blocking mixture based on an ethylene homopolymer or ethylene copolymer with at least one comonomer selected from the group consisting of vinyl esters of a carboxylic acid such as vinyl acetate, kieselguhr, malic acid anthyride, alkyl, alkyl, and alkyl allyl acrylates thereof. 1 to 6 carbon atoms, and 3 to 8 carbon olefins, the composition being characterized in that it contains 200 to 2,500 ppm of talc with a mean particle size in the range of 1 to 5 µm.

The ethylene blend polymers of the present invention generally have a melt flow index in the range of 0.02 to 1 g / min. ^-1 and a bulk density in the range of about 0.905 to 0.935 g.cm &^lt; ³ & gt ^; .

Advantageously, the leaching composition according to the invention contains 200 to 1000 ppm talc.

The ethylene polymers and ethylene polymers with at least one of said comonomers are produced under high pressure (above 100 MPa) in the presence of a free radical initiator. The copolymers of ethylene with at least one Cole-Coleole olefin useful in the present invention are produced either under high pressure (above 30 MPa) and higher temperatures (above 160 ° C) in the presence of a free radical initiator or catalyst system. Ziegler type, or in solution or suspension in a hydrocarbon at moderate pressure (below 10 MPa) and moderate temperature.

Maatek used in the salt according to the invention is a lamella mineral! a structure, extracted from natural quarries, present in crystalline shales and bounding the oxide composition of 3 MgO, 4 SLO ₂ , 1 HgO. Talc. may contain a plurality of! other metal oxides, such as, for example, alumina or iron thyroid.

The compositions of the invention may additionally contain up to 1500 ppm of a glidant, which is preferably an unsaturated fatty acid amide having at least 8 carbon atoms. As . an example of a glidant is stearic acid amide, amide. oleic acid, pateic acid amide, erucic acid amide, bridge acid amide, -benoic acid amide or lauric acid amide.

The compositions of the present invention exhibit remarkable properties compared to compositions containing silicon dioxide in an equivalent moiety. Optical - the properties of films made from these mixtures are the same or even better, especially. frotiblolkijící feature! these foils are better than room temperature! (20 ° C) and / or hot (5 ° C) according to the invention, therefore, can use a smaller amount of additive at the same power output. The invention is greatly improved on both the inner and outer sides of the film compared to compositions containing an equivalent mixture of silica.

The germ mass according to the invention is prepared by uniformly distributing the components in the ethylene polymer in a suitable mixer, either directly in the required amount or by means of a premix of higher concentration. They are suitable for extrusion-blown film production by conventional techniques. The films obtained generally have a thickness in the range of about 7 to 150 µm.

The invention is illustrated by the following examples, without being limited thereto. its scope.

Examples 1 to 5

The mixer - of tomopplymeru Et HYLE melt index taveoioy °, 12 g min ^"1, determined in accordance with A ^STM D-73 123Θ, AOO ^b Jem hmoUio ^s ^ i °, 92 ° g.cm ^- ur ^u en ^E according to ASTM D 2839, prepared homogeirní SMMS obsslující. 250 ppm of oleic acid amide and optionally silica or fuming. The silicon dioxide used in Examples 2 and 4 is an amoophilic synthetic silica. obtained by the wet process. The talc used in Examples 3 and 5 has an average particle size of 3 µm; is supplied under the designation natek 10 MOOS frrmou Sooiété des Talcs de Luzenac.

By extrusion, films having a thickness of 3 ° / µm are produced from the uniformly prepared mixtures. The following characteristics are measured for these films:

- brightness - according to ASTM standard D-1746, expressed as a percentage}

- haze according to ASTM D-1003, expressed as a percentage}

Dyoam cement friction - ASTM D-1894 friction, measured on the bottom and top of the film;

- doping at room temperature! ⁽²⁰ ° C), expressed in ^ e ^ gramophone ^{h s} and measured according to ASTM D-3354th

The values of these properties are given in Table I. As can be seen, Examples 1, 2 and 4 are comparative. Table I example of talc kyssičoík brightness turbidity toožčnOtel blocking (ppm) Silica % · % friction on £ (ppm) bottom top side

1 0 0 55 7.5. 0.35 0.15 39 2 0 250 46 7.9 . 0.50 0.29 35 3 250 0 61 6.4 0.46 0.20 31 4 0 1 000 31 8.9 0.69 0.63 29 5 1 000 0 55 7.1 0.30 0.19 29

Examples 6 to 9

Homogeneous mixtures containing silica or talc and optionally oleic acid amide as a glidant are prepared in the mixer from the ethylene polymer used in the previous examples. Silica and talc are the same as in the previous examples. The films obtained are extruded with a thickness of 30 ° C, which is measured by blocking at 50 ° C by the method described above, expressed in grams.

The amounts of additives used and blocking values are given in Table II. As can be seen, Examples 6 and 8 are comparative.

Table II

example 6 7 8 9 glidant (ppm) 0 0 1 000 1 000 talc (ppm) 0 1 000 0 1 000 Dioxide (ppm) 1 000 0 J 000 0 blocking (g) 58 48 36 28 Example 10 In a blender made of homopolymer ethylene o flow index melt 0.31 g.minV (determined as according to ASTM D 123θ 73) and o bulk density 0,922 g.cm “ ^J (determined according to standard

ASTM D 2839) produces a homogeneous mixture containing talc 10 MOOS by weight

900 ppm of acid oleic acid amide in a mass amount of 400 ppm. From this mixture, films having a thickness of 55 µm are extruded to determine the coefficient of dynamic friction on the underside (ASTM B-894) of brightness (ASTM D-1746) and gloss (D-523). The values of these properties are as follows:

friction: 0,13 brightness: 56% gloss: 98%

Examples 11 to 13

In a mixer, homogeneous is prepared from an ethylene-1-butene copolymer having a melt index of 0.1 g / min (determined according to ASTM D-1238-73) and a bulk density of 0.920 g.cm ^ (determined according to ASTM D-2839). mixtures containing different amounts of talc used in the previous examples. From the blends thus prepared, 25 µm thick films are extruded to measure the dynamic friction coefficient on the outside (ASTM D-1894) and blocking at 70 ° C (ASTM D-3354). The values of these properties are given in Table III. As can be seen, Example 11 is comparative.

Table III

example no. 11 12 13 talc (ppm) 0 500 2 000 blocking (g) 47 34 13 friction (outer side) .0,74 0.62 0.57

Claims (6)

An anti-blocking mixture based on an ethylene homopolymer or copolymer of ethylene with at least one comonomer selected from the group consisting of vinyl esters of a carboxylic acid such as vinyl acetate, carbon monoxide, maleic anhydride, alkyl acrylates and alkyl methacrylates having an alkyl group having 1 to 6 carbon atoms and olefins. having from 3 to 8 carbon atoms, characterized in that it contains 200 to 2,500 ppm of talc with a mean particle size in the range of 1 to 5 дшь 2. The anti-blocking mixture of claim 1, wherein the ethylene polymer has a melt index in the range of 0.02 to 1 g / min. 3. Anti-blocking mixture according to Claims 1 and 2, characterized in that the ethylene polymer has a bulk density of 0.905 to 0.935 g.cnT *. 4. An anti-blocking mixture as claimed in claims 1 to 3 comprising 200 to 1,000 ppm talc. Anti-blocking mixture according to Claims 1 to 4, characterized in that it also contains up to 1500 ppm of a glidant. 6. An anti-blocking composition according to claim 5, wherein the glidant is an unsaturated fatty acid amide of at least 8 carbon atoms.