CS116791A3 - Foil for fresh foodstuffs packaging - Google Patents

Description

Polymers used for packaging fresh meat, assyrian vegetables must provide sanitary protection for the product, must be aesthetically appealing and have characteristics that allow the product to be handled under very different conditions. The film must be strong, rigid, glossy and transparent. It must resist the formation of droplets on its inner surface (hereinafter referred to as "misting") during use. During packaging, the film is stretched and must conform to the shape of the wrapped material, and the film must be sufficiently "held" to maintain its position on the food product until it is sealed. packaging, but it must also be resistant to "blocking" that would prevent it from rolling away. It is also important that the foil can be easily torn off so as to be puncture resistant. Packing must be satisfactory under various conditions commonly used in commercial packaging; The foil must be sufficiently permeable for the oxygen to keep the meat cuts in their attractive red color for three to four days.

Polyvinylchloride is commonly used for the production of fresh meat packaging films. In the food industry, it is difficult to replace it with other, non-halogenated and non-softened materials. Although many base-polyolefin compositions have been proposed, none have satisfied all the diverse market requirements.

Japanese application 53-134591-A discloses a packaging foil having (a) ethylene, (b) 9.7-2.0 mol% alkyl ester acid, (c) 0-2.5 mol% unsaturated (d) 0.3-2.5 mol% metal salt of carboxylic acid. This film has good mechanical, optical properties, including resistance to wetting. IJ .S. Patent 3,048,266 discloses polyolefinic films of unsaturated carbon-carbonic acid, unsaturated and antifoam, and containing as active agents ethylene oxide or polyoxyethylene esters, such as sorbitol and fatty acid mono-and diesters which form fats. Suitable films form polyolefins obtained by copolymerizing ethylene or propylene with, for example, acrylic acids. U.S. Pat. No. 3,048,263 discloses non-misting foil to those disclosed in U.S. Pat. No. 3,048,266. No. 4,189,420 discloses a blend of polyolefinic polybutene as well as a surfactant such as U.S. Pat. Patent resin with small admixture of glyceride and preferably sorbitol fatty acid ester. U.S. Pat. No. 4,486,552 discloses polyolefins of a low density ethylene ethylene ethylene polymer film, a non-misting sepolymer, particularly blended with anti-frosting agents such as (1) a mixed triglyceride alkyl phenol alkoxylate, (2) a polyalkylene fatty acid ester, and (3) a combination (2) of any portion ( 1). U.S. Pat. No. 3,541,040 discloses a non-misting sepolyolefin film made from a blend comprising a polyolefin resin, sodium dioctyl sulfosuccinate, glycerol monostearate, and a reaction product of lauryl alcohol with methylene oxide. U.S. Pat. Patent 3,498,962 discloses olefin polymers containing sarcosine derivatives as anti-freezing agents.

British Patent 1,206,089 discloses a composition comprising a olefin polymer such as polyethylene, 0.25 and a 4% product of ethylene oxide with alcohol 8 and 18% carbon 0.1 to 2%. a polyhydric alcohol esterified with an acid and 0.055 and 0.75% of an alkali metal salt of sulfosuccinic acid. If this composition is processed, then it is not subject to fogging.

French Patent Specification 2,117,386 discloses a packaging product for use on fresh meat composed of an ethylene-vinyl acetate copolymer with 0.5% of a 6% anti-blocking agent, which is a partially esterifying polyol and an aliphatic derivative of its atoms, fatty acid fatty acid or a polyalkyleneoxy monocarbon ester.

The Japanese patent patent application 53-108145-A reports the composition of a partially hydrogenated vinyl acetate copolymer with a low content of 1 liter of an organic polyolefin asorbitol fatty acid ester. The resin is used to produce a stretch film, which is transparent and shiny.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION The present invention provides a process for preparing a packaging film comprising: (a) at least 80% terpolymer containing at least 50 weight percent ethylene, 2 to 20 weight percent unsaturated carbonyl 3 to 8 carbon atoms, and 2 to 20 weight percent components derived from at least one alkyl acrylate, alkyl methacrylate or mixtures of both, wherein the alkyls have 2-12 carbon atoms and wherein the acidic acid moieties are neutralized to 0 to 10 percent by at least one metal ion, and (b) 0.1 to 2 percent by weight of at least one sorbitol fatty acid ester; (corona) at least one side to the extent sufficient to prevent the film from becoming fogged when wet food is wrapped.

The invention further provides a process for preparing a packaging film of which the steps are: (a) mixing a terpolymer of at least 50 weight percent ethylene, 2 to 20 weight percent unsaturated monocarboxylic acid having 3 to 8 carbon atoms, and 2 to 20 weight percent components derived from at least one alkyl acrylate; alkyl methacrylate or mixtures thereof wherein the alkyls have 1 to 2 carbon atoms and the acidic groups of the acid component are neutralized to 0 to 10 percent by at least one metal ion, and 0.1 to 2 percent by at least one sorbitol fatty acid ester; (b) treating the mixture into a film; and (c) treating said film with a corona at least one side to an extent sufficient to prevent the film from fogging if the wet food is wrapped

The present invention further provides packers prepared by enclosing food packaging films

Detailed Description of the Invention

The film described in this invention is primarily prepared from an ethylene-based terpolymer (triple polymer). which is charged by a known free-radical polymerization, e.g. in high temperature in a stirred reactor maintained under constant conditions, of the type described in U.S. Pat. No. 4,351,931. The chemical composition of the polymer is controlled, as is well known, by selecting the appropriate monomer addition rate.

The ethylene terpolymer contains ethylene-derived constituents, about 2 to 20 percent by weight of unsaturated monocarboxylic acid, 3 to 8 carbon atoms, and 2 to 20 percent of at least one alkyl acrylate, alkyl methacrylate, or a mixture of both, alkyl to 1 to 12 carbon atoms. Monocarboxylic acids are preferably acrylic or methacrylic acid, or mixtures thereof are represented by a proportion of 4 to 12 weight percent, but rather 5 to 10 weight percent, and most preferably 6 to 8 weight percent. The presence of the carboxylic acid component in the polymer provides the desired combination of clarity, strength and puncture resistance.

Suitable acrylates or methacrylates are those containing alkyls of 2 to 12 carbon atoms including propyl, isopropyl, n-butyl, isobutyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl and n-dodecyl. . Methyl groups are not favored. Most preferred are isobutyl and n-butyl acrylate. Such ester moieties are preferably comprised of 4 to 12 percent by weight, more preferably 5 to 10 percent by weight, and most preferably 6 to 8 percent by weight. The presence of acrylate or provides the desired high-performance foil.

Most preferred for its general application in this context is the contact of a terpolymer which contains ethylene, methacrylic acid and sobutylacrylate.

The polymer of the present invention can be used in the form of non-neutralized acid terpolymer, or its acidic groups can be neutralized to low degree by metal ions, e.g. up to 10% neutralization. Suitable metals are those that fall within Group I, II, III, IV-A and VII of the Periodic Table of Elements (as shown on page 392 of the Handbook of Chemistry and Methacrylate in Polymeritupert Stretcher and are for food use)

Particularly suitable are sodium, potassium, lithium, cesium, silver-mercury, copper, beryllium-magnesium, calcium, strontium-barium-copper, cadmium, mercury, tin. , lead, iron, cobalt, nickel, zinc, aluminum, although the presence of such metals that are not particularly toxic is preferred for food packaging purposes. Zinc and sodium are most preferred.

In general, a non-neutralized polymer is preferred, although a low degree of neutralization may be desirable, for example, to improve the properties of the film such as melt stability. The amount of ionic neutralization, if any, should be small enough not to reduce the melt idex of the resulting polymer. In order to obtain a suitable film, it is desirable that the polymer has a melt index of 1 to 15, preferably 5 to 12a, preferably 7 to 10 dg / min at 190 ° C according to ASTM D-1238. A high-quality melt index can produce a good quality film at high speed at melting points of about 180 ° C to prevent the anti-fog additive from being volatilized.

The terpolymer may form the entire polymer component of the film, although 18% or even 19.9% of other polymers in the amounts may be added, which will not interfere with the advantages of the present invention. In particular, small amounts of at least one other polymer, such as an ethylene-based anebocopolymer as carrier resin, may be added to form a concentrate for the addition of sorbitol ester fatty acid described below. The amount of carrier resin will normally be 10% or less of the mixture. It has been found that 5% (binary) acid copolymer is quite suitable for this purpose. Normally the terpolymer will comprise at least 80%, preferably at least 90%, of the weight of the film. At least one mono-sorbitol fatty acid ester is added to the polymer to a low degree. Sorbitol fatty acid esters are esters prepared by partial esterification of 8 to 20 carbon atoms with sorbitol and its anhydrides. The preferred ester is sorbitol monolaurate. The amount of the ester in the polymer is 0.1 to 2 weight percent, the T t 1 is 0.3 and the 0.8 weight concentration is about 0.5%. fatty acids provides percentages. Optimal sorbitol ester

Also present with improved anti-fouling properties combined with durability of the veterinary polymer additive concentrate and then anti-blocking while maintaining good clarity. the terpolymer and sorbitol fatty acid ester composition is prepared by mixing the two components together. In general, this mixing will take place in the melting phase. It is generally preferred to prepare a suitable olefin copolymer or to mix the concentrate tablets with the terpolymer tablets prior to filling into the anti-aging agent. Other methods of addition may be used, but in each case the sorbitol fatty acid ester must be added to the polyolefin melted and formed into a film.

The composition can best be formed into a film by a well-known bubble and oriented extrusion process (i.e., blow blow process) followed by shrinkage, fibrillation, film wound processing. ·

The use of a sorbitol ester in a terpolymer film does not provide a satisfactory anti-icing result, apparently because the ester does not migrate to the surface of the film to a sufficient extent to form a continuous water film rather than a separate droplet. However, the use of corona treatment for one strand increases the anti-freeze and other desirable properties in the unexpected range. The manufacture of corona processing equipment is well known and described in, for example, U.S. Pat. No. 3,133,193. Generally speaking, a suitable arrangement consists of a grounded metal cylinder with an insulated cover and an electrode mounted parallel to the cylinder axis. The film crosses the insulated cylinder and produces a corona by the electrode and the film. The electrode pitch, which is the distance between the electrode and the insulated surface of the cylinder, the (final) degree of wetting, as ISM 0-2578, which is measured by the control to define universally and specifically all the parameters suitable for the pro-coronary treatment since they depend! the line speed, the width, the electrode arrangement, the purity of the electrodes, the additives present in the foil, the temperature of the foil, etc. Whoever is in the process of determining the wetting properties and suitable adjustment parameters to obtain its desired degree. A suitable range of treatment is that which provides a wetting tension of 40 to 50 dynes / cp, more preferably 42 to 48 dynes / cm.

The amount of energy that is applied to the film is important 'can be set to desired defined in the standard parameter. Not possible 7 or? a certain minimum amount is required to improve the surface properties of the film. The corona treatment is preferably applied only to that side of the sheet which comes into contact with the contents of the package. 2 of this reason, the apparatus for producing blown film, the corona treatment station, the device f. When splitting the film and winding it up, it should be well understood that some of the fabrication of the apparatus and its geometrical arrangement is such that a suitable degree of processing is achieved, as is clear to anyone skilled in the art. they are designed to provide the role of a foil that will pack food in the desired orientation. Can be applied to both sides of the film. The main effect of the dual action lies in the unfavorable influence of the properties of the film in view of its sealing, in some circumstances the very slight corona second side of the film may be useful. Various possibilities exist Examples of the invention Example 1

Ninety-five parts by weight of the tableted terpolymer ethylene with 6% by weight of isobutylacrylate and 6% by weight of methacrylic acid, melt index 9 dg / min (19CT), are mixed with 5 parts by weight of tableted concentrate of 10 parts of sorbitol in 90 parts of copolymer-ethylene resin and methacrylic acids. The dry mixture is extruded at a temperature, melting at 180 ° C through a 50 mm single screw extruder equipped with a 100 mm diameter circular dowel to obtain a 16 micron film. The film was prepared at a rate of 27 m / min of blown film in which the blown bubble diameter of the die was 4.5 to 1. The film thickness was 16 microns. One surface of the foil was treated with an electric corona using a Kelwar ™ apparatus whose pitch of βp, β, and power was adjusted so that a 44 dynn / cm wetting point measured according to ASTM D 2578 was obtained on the foil surface. with a velocity of 27 m / min, the film obtained was transparent, shiny (105% gloss as determined by ASTM D 2454), and exhibited a high degree of adhesion "

8 is determined manually by pulling the film over the top of the long sleeve, squeezing the film and monitoring its return to its original shape.

The film thus prepared was used to pack a fresh meat tray using a commercial Del ford ™ packaging machine manufactured by Del ford Co.. (Japan). This machine stretches the foil, moves the tray with its contents through the guide wheel, compresses the film around the edges of the tray, and heats it on the bottom of the tray with heat. This is accomplished by joining the foil face to the end of the inner and outer surfaces of the foil. Up to 50 packages per minute can be achieved; packages are very attractive smooth. A similar test was performed on an Ilapak Targa ™ model 50A, manufactured by Ilapak SA, for packaging imitation food products. Performance was also very satisfactory on this equipment.

Setting the temperature of the Del Ford ™ sealer was r Already changed. It has been observed that ζθ could be sealed for which

a foil according to the present invention, a wide range of temperatures between 115 and 150 ° C, was always achieved by good meltbreaking

Traditional food packaging olefin films exhibit an undesirable narrow temperature range in which they can be melted, typically 5-10 ° C (110-120 ° C for ethylene / vinyl acetate copolymer). The sealing temperature range for polyvinyl chloride is about 124-140 ° C even though PVC does not provide genuine fusible bonding under the condition and therefore a common fluid leak is such a joint. 0.5% sorbitol monolaurate and bylastane. All foils by way of example against fogging. According to this test, the glass beakers are filled with Example 2-6

Other films were prepared as described in Example 1, except that the terpolymer composition was varied as shown in Table I. In any case, the extruded composition contained a quartz-treated one-to-six pass resistance test film stretched over the edges with water and beakers were placed either in the refrigerator at 8.8 ° C or in the thermostat at 35 ° C for up to 5 days. beakers are continuously observed to ensure that the condensed water on the underside of the film forms droplets 9 or continuous film. Unless at all times droplets of puffin are formed, they failed the test. Examples of films 2, 3 and 6 were significantly better than optical properties and resistances. tip. The Tests were performed as outlined in Example i using the films shown in Examples 2-5 on the "Mini" machine W18 and W40, which are manufactured by Automac IndustrieSRL (Italy)

Table I

Isobutyl Methacrylic Melt Breakdown "Gloss * Ml Women's Ic Acrylic Acid Ndex Tip" «% *%%% 2 8 8 7 200 112 3.3 3 5 10 7 190 121 4.6 4 10 5 7 160 97 5.7 5 5 5 7 150 88 6.4 6 6 7 260 118 2.5 evg according to ASTM D 1709 b standard ASTM D 2454 c hon ma ASTM D 1003 M ini is a semi-automatic machine with a learning plate and hot plate sealing machine. With the help of all the machines, it was possible to obtain attractive and functionally satisfactory speed packers typical of these machines, the foil prepared according to Example 3 in particular, in terms of strength, clarity and glitter. and providing attractive speed packers for which the device was designed.

COMPARATIVE EXAMPLE A Example 4 was repeated but was not used by electroplating. The foil did not pass the fog test because 10; ' a few hours later, water droplets appeared on it.

COMPARATIVE EXAMPLE B Example 4 was repeated by treating both sides with an electroshock so as to obtain a tensile strength of about 45 dynes / cm. This foil was unsatisfactory in the sealing test carried out in the temperature range of 110 to 150 ° C.

Comparative Example C Example 4 was repeated except that sorbitol monolaurate was substituted with glycerol monooleate. This film did not pass the anti-fog test.

Comparative Example D Example 4 was repeated except that no anti-fog was added and one side was treated with an electric corona to obtain a humidification value of 44 dynes / cm. This foil exhibited poor properties in the testuna fog-resistant because of the large-capped caps. Example 7

The film was prepared as described in Example 6 except that the terpolymer was neutralized with zinc ions to about 5% thereby reducing the melt index to about 5. This film could not be distinguished in terms of functionality from Example 6, passed the anti-fog test and was therefore evaluated as excellent.

These examples show that the polymer films of the present invention have very good properties in packaging machines designed for plasticized polyvinyl chloride films and can be advantageously used wherever non-halogenated packaging material is required.

Claims (17)

• ^ Β8ΒίΗΒ3Ι9ΙΛ &amp; ^ ΐ! Ζΐ <8 &amp; 3Μί! Ί! Βί! ΊΒιΕ) containing at least 80% by weight of unsaturated at least 80% by weight PATENTES 1, Packaging film containing (a) at least 80% terpolymer by percent ethylene, 2% and? 20 weight percent of the 3 to 8 carbon monocarboxylic acid molar percentages of the zalkylacrylate, alkyl methacrylate or mixture component have 2 to 12 carbon atoms, and further wherein the acidic acid moiety is neutralized from 0 to 10 percent by at least one metal ion; and (b) containing 0.1 to 2 percent by weight of at least one fatty sorbitol fatty acid ester, which film is at least one side treated with an electrical corona sufficient to provide a wetted tensile strength of 40 to 50 dynes / cm. 2. The packaging film of claim 1 which has been subjected to an electric corona treatment to achieve 42 to 4q dynes / cm. A wrapping film according to one of the preceding claims, wherein the wrapping film is of the preceding claim. the terpolymer comprises the components or acrylic acid isobutyl acrylate. 4. The polyethylene, methacrylic-butylacrylate, or percent acrylic acid component of the terpolymer is 4 to 12 n-butyl acrylate or the amount of isobutyl acrylate component in the terpolymer is 4 to 12 weight percent. The packaging film according to claim 4, wherein the amount of methacrylic or acrylic acid component in the terpolymer is 5 to 10 and the weight percent of the n-butyl acrylate isobutyl acrylate component is 5 to 10 percent by weight. The packaging film of claim 4 wherein the amount of methacrylic acid or acrylic acid in weight percent and the amount of isobutyl acrylate component in the terpolymer is 6 to 8 weight percent. The packaging film according to one of the above claims in or component of the polymer is 6 to 8-butyl acrylate or wherein the acid components are not neutralized. The packaging foil according to one of the claims is an acid component, neutralized to 1-1% by sodium ions or by M '<- "-% M. Packaging film according to one of Claims 1 to 8, wherein the melt index of the terpolymer is 4 to 12 dg / min at 190 ° C. The packaging film according to one of the preceding claims, in the sorbitol fatty acid ester is a sorbitol monolaurate. 11. Packaging; the film of claim 10 wherein the sorbitol monosurate is 0.3 to 0.8 weight percent. A process for preparing a packaging film according to one of the preceding claims, which comprises the steps (a) of mixing together (i) at least 80% terpolymer containing at least 50% by weight of ethylene, 2 to 20%, - (η percent of unsaturated fatty acid with 3 to q) carbon atoms and 2 to 20 percent by weight of the J component derived from at least one alkylaryl, alkyl methacrylate or mixture of both wherein the alkyls contain 2 to 12 carbon atoms, and further wherein the acidic acid moiety is neutralized to 0 to 10 percent by at least one ionic, and (ii) 0.1 to 2 percent by weight of at least one of the sorbitol fatty acid ester (b) treating the mixture into a film; and (c) treating at least one of the trarios of the aforementioned foil electron corona to a degree sufficient to wet the treated surface of 40 to 50 dynes / cm. 13. The process of Claim 12 wherein the electrolytic corona is applied at a level of 42 to 1 / cm. The process according to one of claims 12 or 13, wherein the polymer comprises components derived from ethylene and components derived from methacrylic or acrylic acid in an amount of 4 to 12 weight percent, and n-butylacrylate and / or isobutylacrylate in an amount of 4 to 12 weight percent. Method according to one of the preceding claims, wherein the sorbitol fatty acid ester is sorbitol monolaurate and forms 0.3 to 0.8 weight percent of the composition i. 16. Packers comprising a film, according to claim 1, enclosing a food product having moisture. 17. Packers comprising a film according to claim 2 enclosing a product exhibiting moisture. 18. A package comprising a film according to claim 4 enclosing a film. 13 í! : '; food product exhibiting moisture. 19. A package comprising a film according to claim 11 enclosing a food product having moisture. n20. The packaging film according to claim 1, in which the terpolymer content is 95%, the terpolymer comprising. 88 ethylene units, 6 weight isobutylacrylate and 6 weight percent methacrylic, and has a melt index of 9 dg / min; the amount of sorbitol fatty acid ester is 0.5%, said sorbitol ester monourea; the sheet is treated with an electric corona on one side to obtain a dye / cm humidifier; the phlephon also contains 4.5% naethylene / methacrylic acid resin. weight percent of the units of copolymer acid units