FI104558B - Optical grade slidable anti-stick composition based on low crystallinity ethylene copolymer - Google Patents

Abstract

The sliding, anti-blocking and optical quality compositions are comprised of at least one ethylene copolymer having a cristallinity not exceeding 30 %; they are characterized in that they further include an efficient quantity of ethylene-bis-oleamide. Said compositions may be conveniently used for the fabrication of plates with a thickness comprised between 1 and 10 mm approximately, and particularly for the production of films with a thickness comprised between 10 and 500 mu m approximately.

Description

104558

The present invention relates to a slippery, anti-adhesive and optical quality composition in the form of fibers, film or sheet containing at least one ethylene copolymer having a crystallinity of not more than 30%: .

In the process industry for converting plastic materials into films, adhesion-10 ("blocking") refers to the adhesion of the film to itself, which may be due to a number of reasons, in particular to the extrusion temperature being too high, but also to the nature of the material. During and after extrusion, in order to avoid blocking of the film coils and to facilitate the opening of the sheath of the polymer obtained by blow extrusion, it is common to add several additives to the polymer to alter the state of the film surface, in particular by moving to the surface. This is particularly the case for ethylene homopolymers and copolymers. Common additives are mineral fillers such as silica or organic fillers such as certain unsaturated fatty acid amides having at least 8 carbon atoms, in particular stearin, olein, palmitine, erusin, myristine, behenin and laurine amides.

20

For example, EP 060178 describes an ethylene polymer-based anti-blocking compound containing 200 to 2500 ppm talc.

The above-mentioned common additives are completely satisfactory for ethylene polymers and copolymers with medium or high crystallinity, i.e. those having at least about 30% crystallinity as determined by X-ray diffraction, especially HDPE (about 0, 96-0.97), radical LDPE (about 0.92-0.93) and linear LDPE, i.e. ethylene copolymers and at least one alpha olefin having 3-8 carbon atoms and a density of about 0.91-0.95 In fact, the addition of up to 2% of any of the 30 blocking agents of these polymers does not adversely or significantly affect other properties, in particular the optical and mechanical properties required of the film.

This does not apply to low-crystalline ethylene copolymers, i.e. those having a crystallinity less than or equal to about 30% as determined by X-ray diffraction. In fact, in this case, a slight deterioration of the optical properties of the films is observed, which is due to the need for larger amounts of common additives to reduce the blockability of the block to an acceptable level. In some extreme cases, such as a polymer containing 70 wt% ethylene and 30 wt% methyl acrylate, not only the optical properties are significantly reduced, but the Bloc hardness is 25 times higher than the usual acceptable level despite 10% -5 addition of an anti-blocking agent such as talc.

Thus, the first problem solved by the invention is the selection of an additive which, when combined with a low-crystalline ethylene copolymer as defined above, allows avoiding blocking without significantly reducing the optical and / or mechanical properties of the films extruded from this copolymer.

In addition, slippage of thermoplastic material is a significant feature in the process industry, where adhesion of the material to the control systems of automatic machines must be avoided. Slippage is often evaluated by the static or dynamic friction coefficient of the outer surface, which measures the ratio of the force required to achieve or maintain the sliding of two surfaces to the force that clamps the surfaces against each other. For regular and trouble-free operation, most machines require an external surface friction coefficient not exceeding about 0.2. This result has hitherto been obtained by incorporating a mixture of a metal salt, a fatty acid and a saturated fatty acid amide, for example a mixture of zinc stearate and erusylamide, into the ethylene polymer. While this solution is effective, it has the disadvantage of having little dosage and control during the two-component process, which is a minor component in relation to the amount of plastic material used as the main raw material.

Thus, another problem which has been solved by the invention is the choice of an additive which, when combined with a low-crystalline ethylene copolymer as defined above, itself enables a static or dynamic friction coefficient of not more than about 0.2 to be obtained. ta.

The invention is based on the surprising finding that these two problems 30 mentioned above can be solved simultaneously by adding an effective amount of ethylene bisoleamide to a low-crystalline ethylene copolymer.

Thus, the first object of the invention is a slippery, anti-blocking and optical quality composition containing at least an ethylene copolymer having a crystallinity of not more than about 30% and characterized in that it further comprises an effective amount of ethylene bisolamide 104558 O o

II

"CH3- (CH2) 7-CH = CH- (CH2) 7-C-NH- (CH2) 2-NH-C- (CH2) 7-CH = CH- (CH2) 7-CH3 , sufficient to reduce the blockability of the composition and / or the static or dynamic coefficient of friction of the outer surface to an acceptable level for processing the composition in question as a function of the machine used in the process and as a function of the intended end application. In most cases, the properties sought are a static or dynamic coefficient of friction on the outer surface of not more than about 0.2, a blockage as determined by the above method, not exceeding about 20 g of optical opacity as determined by ASTM D-1003 of up to about 15%. .

Of the low-crystalline ethylene copolymers that can be used in the compound of the invention, particular mention is made of polar ethylene copolymers having a comonomer content of at least about 0.09 mol per 100 g, for example, one of the following copolymers: ethylene copolymer or one alkyl acrylate having an alkyl group having from 1 to 10 carbon atoms (particularly copolymers of ethylene / methyl acrylate containing at least 8% by weight of acrylate); - copolymers of ethylene and at least one vinylic acid ester of a saturated carboxylic acid having from 2 to 6 carbon atoms, such as vinyl acetate or propionate; terpolymers ethylene / alkyl (meth) acrylate / unsaturated dicarboxylic acid anhydride (containing up to 15 mol% of (meth) acrylate and up to 3 mol% of an anhydride such as maleic anhydride) as described in FR-A -2498609; 30 - copolymers of ethylene / unsaturated glycidyl monomer and terpolymers of ethylene / unsaturated ethylene monomer / unsaturated glycidyl monomer containing up to 50% by weight of glycidyl monomer such as glycidyl methacrylate and monoacryl, triglycidyl butene tricarboxylate and optionally up to 45% by weight of an ethylene monomer such as a vinyl ester of a saturated carboxylic acid of 2-6 carbon atoms, an acrylate of a saturated alcohol or a methacrylate of an ester of maleic acid with a carboxylic acid ester of maleic acid, has 1 to 18 carbon atoms as described in FR-A-2130279; • · 4 104558 - copolymers of ethylene / unsaturated dicarboxylic acid anhydride / polyol poly (meth) acrylate (containing up to 3 mol% of anhydride, up to 0.4 mol% of polyol poly (meth) acrylate and if necessary 13) , 6% alkyl (meth) acyl acylate) as described in EP-A-312459; 5-copolymers of ethylene / alkyl (meth) acrylate / unsaturated dicarboxylic acid N-carboxyalkylimide (containing up to 14 mol% alkyl (meth) acyl acylate, 3 mol% unsaturated N-carboxyalkyl imide and, if necessary, 3 mol) -% unsaturated dicarboxylic acid anhydride) obtained by reacting at 150-300 ° C with an aminoalkyl carboxylic acid and a terpolymer ethylene / -10 alkyl (meth) acrylate / unsaturated dicarboxylic acid anhydride.

Of the low-crystalline ethylene copolymers falling within the scope of the invention, mention may also be made of copolymers having ethylene and at least one alpha-olefin having from 3 to 8 carbon atoms and having a density of not more than 0.910, such as copolymers according to EP 070220 0.905-0.910, - copolymers of a density usually in the range of 0.890-0.905, usually containing 6-10 mol% alpha-olefin, - copolymers having a density in the range of 0.860-0.890, in particular polyolefin rubbers marketed by the 20 * MITSUI brand TAMFER polymers of 78 to 92 mol% of ethylene and 8 to 22 mol% of alpha olefin which is propylene or 1-butene having a density of 0.860 to 0.890, a residual crystallinity of 1 to 14%, a crystalline melting point of J 75 and the average molecular weight is 60-120 kg / mol and the polydispersity index is 2.2-2.7.

: '25 * Polyolefin rubbers consisting of copolymers of ethylene / propylene and / or 1-butene having a flowrate between about 0,3 and 15 dg / min, a density between 0,865 and 0,885 and containing from 77 to 91 mol% of ethylene and 9-23 mol% of propylene and / or 1-butene, characterized in that the crystalline melting point J is about 100-124 ° C. In addition, the rubbers of the invention may be known from at least one of the following factors: - polydispersity of about 3.5-15 and preferably about 4-8, - geometric average molecular weight (determined as below) of about 35-70 kg / mol, and the ratio x of the content of propylene to 1-butene is 35 is obtained from the double equation 0.9084 <d + 0.002 x <0.918, rs; * a 5 104558 - residual crystallinity (measured by the method described below) of about 3-15%.

The crystalline melting temperature J is the temperature determined by the maximum of the post-crystallization melting curve obtained by treating the copolymer sample 5 in three steps as follows: - melting at 8 ° C per minute after 10 ° C up to 150 ° C, then - crystallization at 8 ° C from 150 ° C to 10 ° C, then re-thawing at 8 ° C per minute after 10 ° C up to 150 ° C.

The residual crystallinity is determined by X-ray diffraction of a sample of the copolymer cooled at 5 ° C per hour from 190 ° C to room temperature.

The geometric mean molecular weight is determined by the mathematical equation 15

N = 1

logioMg = Σ WjlogioMi, i = T

Wherein Wj is the weight fraction of material having mass Mj and N is the number of fractions obtained by permeation chromatography.

Such polyolefin rubbers may be obtained by a process of copolymerization at a temperature of about 160-270 ° C at a pressure of about 400-850 * 105 Pa in a gas stream containing from 18 to 42% by volume of ethylene and from 58 to 82% by volume of propylene and / or 1-butene : using a Ziegler-type catalyst system having at least one periodic transition metal of groups IVB, VB, VIB and VIII of that system and at least one organoaluminium compound and, if necessary, at least one chain modifying agent. The catalyst system may further comprise at least one aluminum or magnesium halide. In order to obtain copolymers having properties such as those described above and having a molar ratio of propylene derived parts 35 to 1-butene derived parts 35 of more than 0.5, the gas stream compound used for copolymerization is preferably such that the volume ratio of · 6104558 propvleem 1-butene is greater than about 0. 3 depending on the nature of the catalyst used. This choice has a known effect on the relative reactivity of ethylene, propylene, and 1-butene in copolymerization, and affects the tendency to combine moieties preferably derived from propylene or 1-butene into a macromolecular chain.

Naturally, the composition of the invention may include a mixture of two or more copolymers as described above. In addition to one or more such copolymers, the composition may also contain another thermoplastic polymer for which blocking and sliding problems and optical properties are usually solved by other additives, in particular ethylene polymer or copolymer having a crystallinity of more than 30%, e.g. , 96-0.97), radical LDPE (about 0.92-0.93) and copolymers containing ethylene and at least one alpha olefin having 3-8 carbon atoms and having a density of about 0.91-0.95, - a propylene polymer or copolymer of at least 85 mol% of propylene and 20 parts and not more than 15 mol% of ethylene or alpha olefin having 4 to 8 carbon atoms.

Typically, the low crystalline ethylene copolymer of the composition of the invention has a flow rate - as defined by ASTM D-1238 at 190 ° C of 2.16kg - of about 0.1 to 10 dg / min. The same applies to an ethylene polymer or copolymer having a crystallinity of more than 30%, optionally present in admixture with a low-crystalline ethylene copolymer.

The amount of ethylene bisolamide added to the mixture according to the invention depends on a number of factors, in particular - the nature and amount of the comonomers in the low-crystalline copolymer with ethylene - the flow rate of the low-crystalline copolymer 35 - gauge thickness »» Λ m

J

7 i 7 104558 - the level of desirable properties (blockability, slippage, optical opacity) and combination of properties as a function of the approved process of the composition and the intended use of the article produced.

The choice of the amount of ethylene bisamide is known with the following general points in mind: In most cases, a slightly higher amount of ethylene bisoleamide is preferred when - the crystallinity of the ethylene copolymer is lower, i.e., the comonomer content is higher and the according to the method described, with a lower value of la.

For most of the low-crystalline ethylene copolymers, the desired properties can be obtained using up to 0.8 wt.% And preferably from about 0.1 to 0.6 wt.% Ethylene-bisoleamide relative to the low-crystalline ethylene copolymer.

Although the additional use of conventional additives has the drawbacks described above, it may be desirable in certain cases to add to the composition of the invention 20 at least one conventional anti-blocking agent such as silica, talc or saturated fatty amide, preferably less than about 1% by weight / or - at least one lubricant additive, such as a metal salt of a fatty acid (e.g. zinc stearate), a saturated fatty amide (e.g. erusylamide) or ethylene bis stearic amide, preferably less than about 1% by weight of the mixture.

The composition of the invention may further comprise at least one conventional ethylene copolymer additive, such as an antioxidant such as sterically hindered phenol, mercaptan or phosphorite, -; - ultraviolet absorbers such as substituted benzophenones, substituted phenylbenzotriazoles and sterically hindered amines, - quenchers such as nickel complexes, - mineral or organic pigment such as zinc or titanium oxide.

When the composition according to the invention is intended for special applications, such as the manufacture of films for agricultural use, which require sufficient resistance under certain climatic conditions (ultraviolet or infrared radiation), it may further contain an effective amount of one or more additives capable of improving these special properties. for example, - 1 to 15% by weight of anhydrous kaolinite, for example US-A-4075784, forms a barrier to infrared rays - about 0.5 to 4% by weight of gamma-crystalline iron oxide, for example, according to FR-A-2347405, in the preparation of an opaque thermal film - a mixture of about 10 to 200 ppm ionic iron salt and about 10 to 1000 ppm sulfur, for example according to FR-A-2199757, in the preparation of a light-destroying film, 10 - zinc oxide, for example EP-A-006049 in the manufacture of a transparent film for the packaging of products already a mixture of biodegradable particles, for example, natural amidone and a substance that can undergo auto-oxidation to form peroxide and / or hydroperoxide, for example according to FR-A-22523 85.

The compositions of the invention may be prepared by any process capable of dispersing ethylene bisolamide and, if necessary, other additives in a low-ethylene copolymer. A mixer, extruder or calender may be used, with a further 20 mixing temperatures below 200 ° C and preferably at least 120 ° C.

The compositions of the invention have advantageous applications in the manufacture of sheets having a thickness of about 1-10 mm, and particularly in the manufacture of films having a thickness of about 10-500 µm. Plates containing the composition black according to the invention may be obtained by compression and injection techniques. Films containing the composition of the invention may be obtained by extrusion through a sheet-shaped die or by extrusion blowing at a temperature preferably between 100 and 180 ° C and an expansion level, preferably between about 1.5 and 3.5.

The following examples are illustrative and do not limit the invention.

•. ~

Examples 1 and 2 A copolymer having a flow rate (determined at 190 ° C of 2.16 kg according to 35 ASTM D-1238) of 2.5 dg / min and containing 84.5% by weight of ethylene is used. 15.5% by weight of methyl acrylate. The crystallinity of this copolymer as determined by X-ray diffraction is 19%. To 100 parts by weight of this copolymer is added X parts by weight of "" 1 9 104558 ethylene bisoleamide with stirring on a Brabender twin-screw mixer at a temperature of 110-150 ° C at 40 rpm. The resulting mixture is extruded into a film having a thickness of 50 µm with a B 30 Troester extruder under the following conditions: 5 - temperature profile: 120-170 ° C, - die diameter: 40 mm - slot 1 mm - compression ratio 2.5 - screw speed: 90 r / min 10 - extrusion rate: 4 m / min.

The film obtained is measured: - optical opacity T, expressed as a percentage and as determined by the NFT 54 15 111 method, - blockability B, expressed in grams and determined by the following method with reference to the figures in the Annex. Film sample 1 is placed between two rectangular 100 x 76 mm plates 2 and 3. The ends 4 and 5 of the film, which overlap the plates, are opened and secured to the outside of the plates by means of adhesive. The plates are placed horizontally between jaws 6 and 7 of a fracturing machine. The upper plate 2 is secured to the upper jaw of the machine by a chain 8 allowing the plate to move in all directions, Fig. 1a. The plate 2 is moved vertically at 36 mm / min. In the first step, Fig. Ib, the force Fj required to separate the two layers of the film is determined. In the second step, Fig. 1c, a force ¥ 2 is required to move the film 2 separated by layers of film. Blockability B is determined from the equation B = F1-F2.

The table below shows the properties obtained as a function of the amount of ethylene bisolamide X. 1 2 3 4 5 6

Examples 3-6 (Comparison) 2 * * 3 9 4

Proceed as in Example 1 using the same copolymer but substituting ethylene bisamide 5 for talc marketed by TALCS DE LUZENAC under the trade name 100 MOOS (Examples 6 3 and 4), ethylene bis stearamide (Examples 5 and 6).

»« I • · 10 104558

The following table shows the properties obtained as a function of the amount of additive X. Table

Example 1 2 3 4 5 6 X 0.25 0.75 1.0 5.0 0.25 0.75 B 20 15 180 20 60 20 T 10.3 8.8 15.6 49.4 9.3 14 , 9 5

Example 7 A copolymer having a flow rate (determined at 190 ° C for 2.16 kg according to ASTM D-1238) of 0.3 dg / min and containing 84.5% by weight of ethylene-10 and 15, is used. 5% by weight of methyl acrylate. The crystallinity of this copolymer is 19%. To 100 parts by weight of this copolymer is added 0.5 parts by weight of ethylene bisolamide under stirring under the conditions of Example 1. The resulting film is extruded into a 180 µm film under the conditions of Example 1.

From the resulting film is measured: - dynamic coefficient of friction as determined by the method of NFT 54112 and 0.06 - blockability as determined by the method described in Example 1 and which is 6 g.

Examples 8-10

Proceed as in Example 7 using the same copolymer but replacing ethylene bisoleamide with - 1% zinc stearate (Example 8); in this case, the dynamic coefficient of friction is 0.87 and the blockability is 8 g, - 0.5% ethylene bis stearamide (Example 9); in this case, the dynamic coefficient of friction is 1.20 and the blockability is 30 g in a mixture of 1% talc, 0.25% ethylene bis stearamide and 1% zinc stearate (Example 10); then the dynamic coefficient of friction is 0.87 and the blockability is 5 g.

Claims (9)

An optical grade slidable adhesive preventive composition which is in the form of fibers, films or sheets and comprises at least one ethylene copolymer having a crystallinity not exceeding 30%, characterized in that it further comprises an effective amount of ethylene bisoleamide. Composition according to claim 1, characterized in that the ethylene copolymer is a polar ethylene copolymer with a content of comonomers which at least is equal to 0.09 moles per 100 g of copolymer. Composition according to claim 2, characterized in that the polar ethylene copolymer is selected from copolymers of ethylene and at least one alkyl acrylate or methacrylate, whose alkyl group has from 1 to 10 carbon atoms, copolymers of ethylene and at least one vinyl ester, terpolymers of ethylene. / alkyl (meth) acrylate / unsaturated dicarboxylic anhydride, copolymers of ethylene / unsaturated glycidyl monomer and terpolymers of. ethylene / ethylenically unsaturated monomer / unsaturated glycidyl monomer, copolymers of ethylene / unsaturated dicarboxylic anhydride / polyol poly (meth) acylate and copolymers of ethylene / alkyl (meth) acrylate / N-carboxyalkylimide of an unsaturated dicarboxylic acid. Composition according to claim 1, characterized in that the ethylene copolymer is a copolymer of ethylene and at least one alpha-oletine having from 3 to 8 carbon atoms having a density not higher than 0.910. , Composition according to any one of claims 1 to 4, characterized in that it further comprises an ethylene polymer or copolymer having a crystallinity higher than 30%, or also a propylene polymer or copolymer. * »35 \ 104558 Composition according to any of claims 1 to 4, characterized in that the ethylene copolymer has a flowability index which is between 0.1 and 10 dg / min. ψ Composition according to any of claims 1 to 6, characterized in that it further comprises at most 0.8 wt% ethylene bisoleamide in the ratio of the ethylene copolymer with a crystallinity not exceeding 30%. Composition according to any of claims 1 to 7, characterized in that it further comprises at least one additive which is an anti-sticking agent or an additive which improves slidability, an antioxidant, an ultraviolet ray absorber, an extinguisher or a mineral or organic pigment. . Film, characterized in that it has a thickness between 10 and 500 µm and that it has been obtained by a composition according to any of claims 1 to 8.