JPH04506820A - Film for fresh food packaging - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Fresh food packaging film Background of the invention The present invention provides olefin-based polymers suitable for packaging fresh meat, vegetables and cheese. Regarding film.

Films used for packaging fresh meat, vegetables and cheese are designed to protect the hygiene and aesthetics of the product. It must have a combination of attractiveness and handling characteristics that make it suitable for use under a wide variety of conditions. No. The film must be strong, tough, glossy and transparent. centre The formation of water droplets on the inner surface of the film during use (referred to here as "fogging") ) must be resistant to The film is stretched during packaging. , must conform to the shape of the material being packaged. The film should “adhere” well and The roll must be kept in place until rolling, but it should also be kept in place before unrolling the roll. It must be resistant to "sticking" so that it is not disturbed. centre It is also important that the film tear cleanly and have high puncture resistance. encountered in commercial packaging operations. Satisfactory sealing performance must be obtained under the wide variety of conditions encountered. oxygen The transparency of the red meat must be sufficiently high that the red meat fillet retains its attractive color for 3.4 days. No.

Currently, fresh meat packaging films are usually highly plasticized polyvinyl chloride. Ru. Replacement of this material with non-halogenated, non-plasticized materials in the food industry There is a strong desire to do so. Polyolefin-based formulations of However, none has succeeded in meeting all the huge demands of the market.

Japanese Patent Application No. 53-134591-A discloses (a) ethylene, (b) 9.7-2. 0 mol% alkyl ester of unsaturated carboxylic acid, (C) 0-2.5 mol% unsaturated carboxylic acid saturated carboxylic acids, and (d) 0.3-2.5 mol % metal salts of unsaturated carboxylic acids. Discloses a packaging film containing as a component. The film has excellent mechanical, heat and light resistance It has good chemical properties and anti-fog properties.

U.S. Patent No. 3,048,266 discloses that ethylene oxide or polyoxyethylene Esters or ethers, such as sorbitan mono- or ethers of lipogenic fatty acids Discloses an anti-fog polyolefin film containing an anti-fog agent such as Tel. Appropriate Film-forming polyolefins include ethylene or propylene, such as acrylic acid. This includes polymers obtained by copolymerizing with.

U.S. Patent 3.048.263 is a file of U.S. Patent 3.048.266. discloses an anti-fog polyolefin film similar to Lum.

U.S. Patent No. 4,189.4.20 discloses a polyolefin resin and a small amount of low molecular weight polymer Tables such as libtenes, mixed glycerides, and preferably sorbitan fatty acid esters. Discloses mixtures with surface wetting agents.

US Patent No. 4.486.552 discloses that (1) alkoxy along with mixed triglycerides late alkylphenol, (2) polyalkylene fatty acid ester, and (3) Ethylene mixed with an antifogging agent such as a combination of (2) and (1) in any proportion anti-fog polyolefin films made of polymers, especially linear low-density ethylene polymers. Disclosed.

U.S. Patent No. 3,541.040 discloses polyolefin resin, dioctyl sulfocarbon Sodium succinate, glycerol monostearate, and lauryl alcohol Anti-fog polyolefin made from a mixture containing the reaction product of ethylene oxide The film is disclosed.

U, S Patent 3,498. ．． 962 is an oil containing a sarcosine derivative as an antifogging agent. A refin polymer is disclosed.

British patent 1.206,089 describes olefin polymers such as polyethylene; ．． Reaction product of 25-4% ethylene oxide and alcohol having 8-18 carbon atoms Polyhydric alcohol esterified with 011-2% fatty acid; and 0.05-0 ．． A formulation containing 75% of an alkali metal salt of a diester of sulfosuccinic acid and an alcohol. The compound is disclosed. When made into a film, the formulation is claimed to never cloud. There is.

French patent publication 2.1.17.3.86 describes ethylene vinyl acetate copolymer mer and 0.5-6% of partial esters of polyols and aliphatic monocarboxylic acids or Contains an antifogging agent consisting of one polyalkylene ogyne derivative of ester, for fresh and meat use. A packaging film is disclosed.

From copolymer and small amount of low molecular weight polyolefin and sorbitan fatty acid ester Discloses a resin formulation consisting of: Using resin, it is transparent, glossy, and anti-fog. Manufacture stretched film.

Summary of the invention The present invention (a) at least 50% by weight ethylene, 2-20% by weight, carbon number 3-8; unsaturated monocarboxylic acid, and 2-20% by weight of alkyl groups having 2-1 carbon atoms; at least one kind of alkyl acrylate, alkyl methacrylate or this It consists of a portion derived from a mixture of these, and the acid-containing portion contains less than 0-10% of the acid groups. At least 80% of the terpolymer is neutralized by at least one metal ion. %; and (b) 0.1-2% by weight of a small amount (both of one type of sorbitan fatty acid ester) of the film when packaging wet food, at least on one side of the film. Provide 1 lum of packaging with sufficient corona treatment to prevent fogging.

The invention further provides a method for making a packaging film: (a) at least 50% by weight; of ethylene, 2-20% by weight of an unsaturated monocarboxylic acid having 3-8 carbon atoms, and 2-20% by weight of at least one alkyl group having 2-12 carbon atoms; moieties derived from alkyl acrylates, alkyl methacrylates or mixtures thereof 0-10% of the acid groups in the acid-containing part are formed by at least one metal ion. at least 80% of the terpolymer is neutralized; and 0. L = 2% by weight, (b) filling the formulation with at least one sorbitan fatty acid ester; Mutoshi; characterized by including a step of applying corona treatment to a degree sufficient to prevent fogging of the film; We provide a method to do this.

The present invention further provides a packaged product in which a food product is sealed with such a packaging film.

Detailed description of the invention The film of the present invention is mainly produced using well-known radical polymerization methods, such as U, S, Patent No. 4,35 1,931 at elevated temperatures in a stirred steady-state-environment reactor of the type described in It is manufactured from a terpolymer of ethylene produced by The chemical composition of the polymer is It is controlled by choosing the appropriate monomer feed rate as is known.

The ethylene terpolymer contains from about 2 to about 20% by weight of a portion derived from ethylene. A portion derived from an unsaturated monocarboxylic acid having 3 to 8 carbon atoms, and 2 to 20% by weight at least one type of alkyl acrylate whose alkyl group has 1 to 12 carbon atoms, methacrylates, alkyl methacrylates, or mixtures thereof. Mo The nocarboxylic acid may be acrylic acid or methacrylic acid, or a mixture thereof. preferably 4-12% by weight, more preferably 5-10% by weight, most preferably is also preferably present in an amount of 6-8% by weight. Presence of carboxylic acid in the polymer Especially propyl, n-butyl, isobutyl, n-pentyl, n-hexyl, n- C2-12 carbon atoms containing octyl, 2-ethylhexyl and n-dodecyl groups. having an alkyl group; a methyl group is not preferred as the alkyl group. Isobuti and n-butyl acrylate are most preferred. Such ester moieties are Preferably 4-12% by weight, more preferably 5-10% by weight, most preferably 6- Present in an amount of 8% by weight. Alkyl acrylate or methacrylate in the polymer The presence of this material gives the film the desired excellent stretchability and flexibility. Ru.

The most preferred ternary polymer in terms of general acceptability for food contact applications. The polymer consists of ethylene, methacrylic acid and imbutyl acrylate.

The polymers of the invention can be used in the form of non-neutralized acidic triphotopolymers, and are Or neutralize the acid groups with a small amount of metal ions, for example up to about 10%. Can be done. Suitable metals include (Handbook of Chemistry a) nd Physics, Chemica I Rubber Publishing g, Co,, 37th edition, page 392 i, Jc! ff1 (D) Periodic Table of Elements! , I Included are metals of groups I, II, IV-A, and VII. Especially Natori potassium, lithium, cesium, silver mercury, copper, beryllium magnesium, Calcium, strontium barium copper, cadmium, mercury, tin, lead, iron, copper metal, nickel, zinc and aluminum are suitable, but for use in food packaging Metals that are not particularly toxic are preferred. Zinc and sodium are most preferred.

It is generally preferred that the polymer be unneutralized, but A low degree of neutralization may be desirable to improve properties.

If present, the amount of neutralizing metal ions will depend on the melt index of the resulting polymer. It must be in a small enough amount so as not to reduce the mass too much. suitable fill To form a polymer, the melt index of the polymer is ASTM D-12. 1-15, preferably 5-12, most preferably measured at 190°C by 77-1 Od/min is desirable.

At this preferred melt index, products can be produced at high speed with a melt temperature of about 180°C. It is possible to produce a film of excellent quality, which prevents the volatilization of the antifogging agent. can.

The terpolymer can be all of the polymeric components of the film, but up to 18 % or as much as 19.9% of other polymers in amounts that do not detract from the advantages of the present invention. Can be done. In particular at least one second polymer, such as an ethylene-based polymer. Mopolymers or copolymers as carrier resins, i.e. sorbitan Small amounts can be added to provide concentration for the addition of fatty acid esters. tree The amount of carrier resin will normally be 10% or less of the formulation; for this purpose about 5%. amounts of (dual) acid copolymers have been found to be very suitable. Usually ternary poly The polymer constitutes at least 80%, preferably at least 90% by weight of the film. to be accomplished.

A small amount of at least one sorbitan fatty acid ester is added to the polymer. So Rubitan fatty acid ester is composed of sorbitol and its anhydride and a carbon number of 8-20. It is a partial ester of fatty acids. The preferred ester is sorbitan monolaurate. The amount of ester in some polymers ranges from about 0.1% to about 2% by weight, preferably from 0.3% to about 2% by weight. It is 0.8% by weight. The optimum concentration is about 0.5%. Sorbitan fatty acid ester The presence of gives excellent anti-fog performance, prevents stickiness and at the same time can maintain high transparency.

Blends of terpolymer and sorbitan fatty acid ester are made by blending the two components together. Manufactured by. Generally, this compounding is done in the melt phase. Suitable olefin copolymers or prepare a concentrate of the additive in the terpolymer and feed it to the film extruder. Tri-blending the concentrate pellets with ternary polymer pellets before Generally simple. Other insertion methods can be used if necessary, but in any case of sorbitan fatty acid esters before melting the terpolymer and forming it into a film. Make additions.

The formulation is prepared by the well-known bubble extrusion and drawing process (i.e. blown fibre). film method), followed by bubble destruction, splitting, processing and film winding. It is preferable to form a film by doing this.

The use of sorbitan esters in ternary polymer films probably does not separate water droplets. Apply it to the surface of the film sufficiently to form a continuous film of water without letting it separate. does not move, so it alone does not provide satisfactory anti-fog performance. But fi Applying a corona treatment to one side of the lume provides unexpected improvements in anti-fog properties and other desirable properties. go up

Equipment for corona treatment of films is well known in the literature, e.g. , patent 3.133.193. Generally suitable equipment configurations include Grounded metal roll with edge cover and embedded parallel to the cylinder axis of the roll Includes soldered electrodes. The film passes over an insulated roll, and between the electrode and the film Generates corona. The electrode gap, which is the distance between the electrode and the insulating roll cover, is AST Wet tension, which is a measurement control parameter defined in M D-2578, is desired. can be adjusted to the value of Suitable operating parameters for corona treatment are Line speed, film width, electrode placement and cleanliness, additives in the film, film All of these cannot be universally specified as they depend on the film temperature. . However, it is important to determine the wet tension and apply the relevant parameters to achieve the desired value. The appropriate adjustments are well within the ability of those skilled in the art.

A suitable range for treatment is 4Q-5Qdynes/am, preferably 42-48dynes/am. This range provides a wet tension of nes/cm.

the lowest amount of energy to achieve the desired improvement in the surface properties of the film The amount of energy applied to the film is important because the Corona treatment Preferably, the treatment is applied only to the side of the film that will come into contact with the contents of the package. stomach. Therefore, blown film production lines, corona treatment locations, film spray The liter and take-up equipment is used to feed the final film into the food packaging machine in the desired direction. Must be assembled correctly to produce Murol. Of course film It is also possible to process both sides. The main effect of such double-sided treatment is the heat seal In some cases a very light corona treatment on the second side may be necessary, although this may have a negative impact on the panel performance. It is for use. As will be apparent to those skilled in the art, various equipment and Geometrical arrangements are possible.

Example 1 Melt containing 6% by weight isobutyl acrylate and 6% by weight methacrylic acid Pelletized ethylene terpolymer 9 with index 9’dg/min (190°C) 5 parts by weight of sorbitan monolayer was added to 90 parts of ethylene methacrylic acid copolymer resin. It was blended with 5 parts by weight of a pelletizing concentrate containing 10 parts of chloride. with a diameter of 100mm The melt is passed through a 50 mm single screw extruder equipped with a circular die. Triblend was extruded at a temperature of 180°C to form a 16 micrometer film. I got it. The film has an inflation ratio of 4.5:1 bubble diameter to die diameter. It was produced in the slow film method at a speed of 27 m/min. The thickness of the film is 16 It was a micrometer. One side of the film was coated with a Kalwar'r Rona device. The wet tension of the film surface is 44dy as measured by ASTM D-2578. Corona treatment was performed by adjusting the electrode gap and power settings so that nes/cm. . The film was passed under a discharge at 27 m/min. The resulting film is transparent and glossy (ASTM D 2454+: Gloss level determined by 105%), wide mouth by stretching the film over the top of the bottle, compressing it with your fingers, and observing its recovery. It showed a high degree of adhesion and elasticity as determined manually.

The film thus produced was sent to Delford Co. (Japan) for production. Pack fresh meat in trays using a commercial Delford meat packing machine. I used it for. This machine stretches the film and passes the web through the tray and its interior. Push the container down, lower the film around the side of the tray, and use the heat seal to seal the film. Seal the film under a tray. Heat sealing is done by sealing the inner and outer surfaces of the filler and lumen. Formed from front to back in between.

Speeds of up to 50 packages per minute have been achieved and the packages are attractive and smooth. Ta. Llap’ak Targa”Mo manufactured by l1apak SA A similar test was conducted on the Del 50 machine to package counterfeit foods. this machine The performance in was also very satisfactory.

The temperature setting of the heat seal plate of the "Delford" machine was changed. The membrane can be sealed over a wide temperature range of 115-150℃ and has a robust melt seal. It was observed that the Traditional olefin films for food packaging are Unfortunately, it always exhibits a narrow sealing range, typically only 5-10°C (e.g. (110-120°C) for tyrene/vinyl acetate copolymers. polyviny The sealing range of polychloride film is about 124-140°C, but PvC does not give a true fused seal under conditions such as leakage of liquid through such a seal. It is common for

Example 2-6 The composition of the terpolymer was varied as shown in Table I using the method of Example 1. A further film was produced. In both cases, the extrusion formulation was 0.5% Sol. Contains bitanium monolaurate and is corona treated on one side.

Table■ 2 8 8 7 200112 3.33 5 10 7 190121 2. 64 10 5 7 160 97 5.75 5 5 7150886.4 6 6 7 26011.8 2.5a, in accordance with ASTM D 1709, Expressed as g.

b, ASTM D 2454° c, ASTM D 1003° Example] All of the films of No. 6 passed the test regarding anti-fog performance.

In this test, a lid was placed over the top of two glass beakers half-filled with water. Stretch out the film sample and place the beaker in a refrigerator at 8.8°C or in a furnace at 350°C. 5 days in the apparatus (.Observe the beaker often to see if water condensed on the lower side of the film as water droplets. Check to see if it is a continuous film.

If at any point water droplets form and obstruct visibility, the film fails the test. considered to be of high rank.

Examples 2.3 and 6 are very superior to the others in terms of optical properties and bullet fracture resistance. It was

Using the film of Example 2-5, Automac Industria SRL ( On "Mini" aircraft manufactured by Italy), as well as on W18 and W40 aircraft, the example A packaging test was conducted as described in 1. Mini is a semi-automatic machine, manual supply and heat Has a board sealer. W18 and W2O are high speed automatic machines, heated conveyor Has sealing. For all films, typically used on these machines We were able to obtain attractive and functional packaging products at a speed that was affordable. Example 3 The film had particularly good sealing properties, transparency and gloss. Automac” on board Testing of the film of Example 6 in A packaged product was produced and an excellent balance of performance properties was demonstrated.

Water droplets appeared on the ilm and the film failed the haze test.

Comparative example B Repeat Example 4 and apply corona treatment to both sides of the film to give approximately 45 dynes/ A wet tension of cm was obtained. When tested in the range of 110-150℃, this film Heat roll performance was unsatisfactory.

Comparative example C Substituting glycerol monooleate for sorbitan monolaurate, Example 4 was repeated. This film failed the fog test and was produced without an antifog agent. Repeat Example 4 with corona treatment on one side and wet tension of 44 dynes/cm. I got it. This film had very fast water droplet formation and performed very poorly in the haze test. .

The ternary polymer is neutralized by about 5% using zinc ions, and the melt inde nox is about 5%. A film identical to Example 6 was produced, except that the film was reduced to . Film is important for performance. was indistinguishable from Example 6, passed the haze test, and was therefore rated as excellent. It was done.

The above examples demonstrate that the polymer film of the present invention is made of plasticized polyvinyl chloride fibre. It performs very well in packaging equipment designed for use with non-halogenated packaging. This shows that it can be used advantageously even if a mounting material is required.

international search report l10. Engineering 401. Yu, Shi, PCT/EP 90100664 International Investigation Report S^　36232

Claims (20)

[Claims] 1. In packaging film: (a) at least 50% by weight of ethylene, 2-20% by weight of carbon atoms of 3-8; unsaturated monocarboxylic acids, and 2-20% by weight of alkyl groups having 2-12 carbon atoms; at least one alkyl acrylate, alkyl methacrylate, or It consists of a part derived from a mixture of At least 80% of the terpolymer is neutralized by one type of metal ion. and (b) 0.1-2% by weight of at least one sorbitan fatty acid ester. at least one side of the film has a wet tension of 40-50 d on the treated side. It is characterized by having been subjected to sufficient corona treatment to achieve packaging film. 2. In the packaging film according to item 1, the moisture content is 42-48 dynes/cm. A film characterized by being subjected to a corona treatment that imparts tension. 3. In the packaging film according to paragraph 1, the terpolymer is derived from ethylene. moieties derived from methacrylic acid or acrylic acid, and n-butyl acrylic acrylate or isobutyl acrylate. Film. 4. In the packaging film according to paragraph 3, methacrylic acid or The amount of acrylic acid moieties is 4-12% by weight and n-butyl acrylate in the terpolymer. Particularly, the amount of rylate or isobutyl acrylate moiety is 4-12% by weight. A film with characteristics. 5. In the packaging film according to paragraph 4, methacrylic acid or The amount of acrylic acid moieties is 5-10% by weight and n-butyl acrylate in the terpolymer. Particularly, the amount of rylate or isobutyl acrylate moiety is 5-10% by weight. A film with characteristics. 6. In the packaging film according to paragraph 4, methacrylic acid or The amount of acrylic acid moieties is 6-8% by weight and n-butyl acrylic in the terpolymer. characterized in that the amount of ester or isobutyl acrylate moiety is 6-8% by weight. A film to do. 7. In the packaging film described in paragraph 1, it is specified that the acid part is not neutralized. A film with characteristics. 8. In the packaging film according to paragraph 1, 1-6% of the acid moiety is sodium or A film characterized by being neutralized by zinc ions. 9. In the packaging film according to item 3, the melt index of the terpolymer is 4-12 dg/min at 190°C. 10. In the packaging film described in item 1, the sorbitan fatty acid ester is A film characterized by being bitanium monolaurate. 11. In the packaging film according to paragraph 10, the amount of sorbitan monolaurate 0.3-0.8% by weight. 12. In the manufacturing method of packaging film: (a) below. (i) at least 50% by weight of ethylene, 2-20% by weight of carbon atoms of 3-8; unsaturated monocarboxylic acids, and 2-20% by weight of alkyl groups having 2-12 carbon atoms; at least one alkyl acrylate, alkyl methacrylate, or It consists of a part derived from a mixture of At least 80% of the terpolymer is neutralized by one type of metal ion. and (ii) 0.1-2% by weight of at least one sorbitan fatty acid ester. Combined with tel; (b) the blend is a film; (c) at least one side of the film has a treated surface wet tension of 40-50 dyn; es/cm. How to do it. 13. In the method described in paragraph 12, A method characterized by performing a na treatment. 14. In the method according to paragraph 12, the terpolymer is derived from ethylene. 4-12% by weight of moieties derived from methacrylic acid or acrylic acid, and 4-12% by weight of moieties derived from methacrylic acid or acrylic acid; Derived from 12% by weight of n-butyl acrylate or isobutyl acrylate A method characterized in that it includes a part. 15. In the method described in item 12, the sorbitan fatty acid ester is sorbitan laurate and constitutes 0.3-0.8% by weight in the formulation. . 16. A package in which a moisture-containing food is wrapped with the film according to item 1. 17. A package in which a moisture-containing food is wrapped with the film according to item 2. 18. A package in which a moisture-containing food is wrapped with the film according to item 4. 19. A packaged product comprising a moisture-containing food packaged with the film according to item 11. 20. In the packaging film according to paragraph 1, the amount of terpolymer is 95%; , the terpolymer is 88% by weight ethylene units, 6% by weight isobutyl acrylate. and 6% by weight of methacrylic acid units, and has a melt index of 9d. g/min; the amount of sorbitan fatty acid ester is 0.5%, and the ester is Sorbitan monolaurate; 44 dynes/cm on one side of the film. corona treatment to provide wet tension; the film is further coated with 4.5% ethylene/ A film comprising a methacrylic acid copolymer resin.