SU657756A3 - Polymer composition for manufacturing films - Google Patents

Description

Homo- or copolymer of ethylene or propylene95-99.9 Block or graft copolymer0; The block copolymers used in the compositions described can be obtained by polymerization in the first stage of an olefin in the presence of dialkylzinc and coordination catalysts and then in the second stage by polymerization of styrene monomer a using a catalyst containing free radicals, in the presence of an unactivated polymer obtained in the first step. As for the graft copolymer, it can be obtained by various cognates known in this industry. In particular, the method of grafting in water suspension can be used to obtain it. The graft copolymer is obtained, in particular, by inoculation of monomer by erasing on the basis of polyethylene or unstitched polypropylene. in the block or graft copolymer the olefin part i.e. formed by ethylene or propylene, preferably in the range of 30-95% and preferably 60-95% by weight of the copolymer. The melt index of the grafted or block copoly measure in the inventive compositions may vary from up to 20, and preferably in the range of 0.5-5. The conditions for determining the melt index of the polymer are specified in numbers A TM-123 B5 T. The dose of the block or graft copolymer incorporated into the polyolefin for the preparation of the proposed compositions is preferably in the range of 0.1-2% by weight of the polyolefin. Block or graft copolymer on. in a polyolefin to obtain the proposed compositions by mixing well-known specialists in this field, in particular by smearing in a molten state in a black mixer. For example, you can proceed in the following way. A basic mixture of a block or graft copolymer and 1 hour of polyolefin in an auxiliary mixer is prepared, then the product from said mixer is mixed in appropriate proportions with the polyolefin in an extruder. The mixture leaving the extruder is granulated and then injected into a JineHOK extrusion device, which may be an extrusion blow molding machine. I Example. Polyethylene c: melt 4 ndocca and melt density 4.924 is used to prepare ten compositions A, B D, E, Fj.G, H, J, NyE by mixing components in a twin-screw extruder of the We6ding type. The rotation speed of the 1 screw is 100 rpm, the temperature is 200 ° C. Then, the product coming out of the extruder is granulated and injected into a plasticizing screw to BattenfeCd 10 VP 25 type. The granulated compositions thus obtained are extruded into casings by means of extrusion blow molding on an extruder of Samafor B-65 type shells. These shells have a width of approximately 50 cm and a thickness of 50 μm. On the shells obtained from different compositions, two indicators are determined, namely the adhesion force characterizing the adhesion (caking) of the shells - the "contrast ratio" that determines the transparency of the films. Here, the sticking force is understood to mean the amount expressed in gram-force, necessary for the separation of two films 1.3 cm wide, by shifting and for sticking the film superimposed on each other by a length of 10 cm. This g value is higher, the greater the adhesion between these films. The contrast ratio is expressed by the ratio: C% fe-Hoo, where Meath represents the minimum and maximum light fluxes transmitted by the sinusoidal world, on which they form an image of the slit of a collimator emitting a parallel beam of light that passes through the sample under study. The contrast ratio, which is a function of the transparency of the sample, varies in. the same direction as this transparency. Block or grafted PE / PS at X% PE means block or graft polyethylene / polystyrene copolymer, at X wt.% Polyethylene. Shells made from C, D, E, and H, 3, J, K, L, .t. i of the proposed constructions have a reduced slippiness compared to the adhesions of shells made from a single polyethylene (composition A) or polyethylene containing an anti-sticking additive in accordance with previous methods, in this case silica gel (composition B). In addition, if we consider the contrast ratio, it turns out that the transparency of the shells made from the proposed compositions remains almost the same (compositions C, E, H, J, K, L) as the transparency of the shells of the same polyethylene (composition ../) or significantly improved (composition D and p), while the transparency of the films prepared from composition B is significantly reduced. It can also be noted that compositions containing a block (composition F) or graft copolymer (composition G) content above 50% give adhesions with adhesion which is smaller than those made of polyethylene, however, their transparency is greatly reduced, which makes them not applicable in conventional applications where perfect transparency is required.

Example 2 Based on a copolymer of ethylene and vinyl acetate (EVY), obtained by polymerization with free radicals in a high-pressure tubular reactor, the copolymer that contains 4.8 wt.%

of vinyl acetate and has a melt index of 0.6, five compositions of M, N, 0 / P and Q are prepared. These shells are extruded: as in Example 1.

For the shells obtained, two indicators are determined, namely, the adhesion force, which characterizes the stickiness (tracking) and the contrast ratio, an indicator of their transparency.

Table 1 shows the data characterizing the various compositions, as well as the values of certain indicators determined for the casings, which are made from each composition.

100 tab. 2 shows the data, which characterizes various compositions, as well as the values of the indices j

Table

75

330 dimension e1 "them for the corresponding shells obtained from these compositions.

flint

98PEL / PS2 unit

(80% PE)

99.2Privity PE / PS1

(80% PE)

99.2 Block PE / Poly-0.8 tilstyral-styrene (94% PE)

The films obtained from the proposed compositions O, P, less stick together compared with the stickiness of the films, exhausted from a single copolymer EV (composition M), while maintaining transparency, identical transparency of the films from the composition M.

Films made from a composition containing silicon dioxide (composition N) are less adherent than films made from a single EPA copolymer (caking reduction), however, their transparency is greatly reduced.

polypropylene / polystyrene block or graft copolymer.

Shells made from the proposed compositions T, U, V, less stickiness compared with the stickiness of membranes made from only one polypropylene (composition R7, having identical or improved transparency.

table 2

150

32 45 48

300

350

Example 3: Based on polypropylene, five Compositions R, S, T, U, V are prepared. They are extruded to produce films as in Example 1.

For the resulting shells, the stickiness and contrast ratio are determined.

Table 3 shows the data characterizing the various compositions, as well as the values of the specific indicators measured for the casings, which are made from these compositions.

Table

In contrast, the shells of the composition containing silicon dioxide (composition S) are much less transparent.

Example 4. A copolymer of propylene and ethylene, containing 2% ethylene and with a melt index of 6 (determined at), was introduced 0.6

weight,% graft copolymer, obtained by grafting styrene on unstitched polyethylene. The specified graft copolymer contains .80 wt.% Of ethylene and has a melt index of 1.4.

The resulting composition is extruded to make shells 60 microns thick.

Fabricated shells have a slipability which is approximately one of the sheathing properties of shells made from a single ethylene / propylene copolymer without reducing transparency.

Claims (1)

Invention Formula A polymer composition for the manufacture of films, containing an ethylene or propylene homo or copolymer and an additive, characterized in that, in order to reduce the adhesion of the films while maintaining their transparency, selected from the group comprising styrene, methylstyrene and chlorostyrene, moreover, the specified copolymer contains 30-95 weight,% units of ethylene or propylene, in the following ratio of components, wt.%: Homo or copolymer ethylene or propylene 95-99.9 Block or graft copolymer0,1-5 Priority featured: 29,12,70 - block copolymer; 12.28.72- graft copolymer; 13.12.73- content of grafted ethylene or propylene. Sources of information taken into account in the examination 1, European Potymer JornaC, 1968, v, 4, RL73-185,