CA1043931A

CA1043931A - High density polyethylene aluminum filled film as butter and margarine wrap

Info

Publication number: CA1043931A
Application number: CA229,826A
Authority: CA
Inventors: Ted M. Tuszynski
Original assignee: DuPont Canada Inc
Current assignee: DuPont Canada Inc
Priority date: 1975-06-20
Filing date: 1975-06-20
Publication date: 1978-12-05

Abstract

ABSTRACT OF THE DISCLOSURE
A wrapping material for butter or margarine is disclosed which comprises a high density polyethylene film made form polyethylene having a density in the range of from 0.945 to 0.970 g/cm3 and containing finely divided aluminum pigment, the aluminum pigment being present in an amount of at least 0.1 g/m2 of the film and the film having a thickness in the range of from 15 to 200 µm. The wrapping material of the present invention is more effective in protecting butter or margarine from deterioration of its flavour upon a storage in a brightly illuminated display case than are the conventional butter parchment paper and the thermoplastic films used heretofore for wrapping butter or margarine.

Description

~01~ 3~
The present invention relates to high density polyethylene films for wrapping butter and margarine and more particularlly to such high den~ity polyethylene films containing finely divided a'uminum pigment.
At present butter and margarine are usually wrapped in parchment or aluminum ~oil. Recently, paper-like thermoplastic films have become available as wrapping material for butter and margarine. Canadian application Serial No. 186,508 which was filed November 22, 1973 on an invention by V.G. Zboril descrlbes such a paper-like thermoplastic film.
Aluminum foil is a good wrapping material for butter and margarine. However, aluminum foil tend~ to be expensive. Parchment and the known thermoplastic ~ilms such as the paper-like thermoplastic films discussed above are more economical than aluminum foil, but have the disadvantage that when butter or margarine is wrapped therein and stored in a brightly illuminated display case~the flavour of the butter or margarine tends to deteriorateO Attempts to overcome ~his disadvantage of such paper-like therm~-plastic film by the addition of the pigment TiO2 were ~`~
unsuccessful as is discussed hereinafter.
It is an ob~ect of the present invention to providea wrapping material for butter or margarine which is more ec~nomical than aluminum foil and which is more ef~ective than parchment ~nd the known thermoplastic films in protecting butter or margarine from deterioration of its flavour upon stoIage in a brlghtly illuminated display case.
With this ob~ect in view,the present invention provides wrapping material for butter or margarine comprislng a high density polyethylene film made from polyethylene having a density in the range of from 0.945 to 0.970 g/cm3 3~3~

and containing finely divided aluminum pigment, the aluminum pigment being pre~ent in an amount o~ at least 0.1 g/m2 O~
the film and the film havlng a thLckness in the range o~ from 15 to 200~um.
In one embodiment of the present invention, the aluminum pigment is present in an amount in the range of from 0.5 to 3.0 g/m2 of the film and the film has a thickness in the range of from 20 to 60 ,urn.
In another embodiment of the present invention, the film also contains mica particles, the mica particles being present in an amount in the range of ~rom 1.5 to 4.5 g/m2 of film, the largest dimension of the mica particles being less than 150,um.
The film comprising the wrapping material of the present invention may be prepared by a blown film or other process~
from any film-~orming polyethylene having a density in the range of from 0.945 to 0.970 g/cm3 and containing alumlnum pigment as described above. Preferably, however, the polymer of the blown film is a polyethylene having a densitg in the range of from 0.945 to 0.970 g/cm3, a melt flow index (Ml:) in the range of from 0.1 to 2.0 especially in the range of from 0,4 to 1.5 decigrams per minute and a stress exponent (S.E.) in the range of from 1.6 to 2Ø
The melt flow index (M::) o~ the polyethylene is measured according to the procedures o~ A.S.T.M. D-1238.
Stress exponent (S~Eo ) is discussed in Canadian Patent 664,699 which issued 11th June, 1963 to C.E. Ashby, S.P. Foster and E.T. Pieski and in Canadian Patent 771,260 which issued 7th Noveniber 1967 to D.J. Ryan and B.J. Starkey.
3 The stress exponent is determined by measuring the throughput of a melt indexer at two stresses (2160 and 6480g loading) .. . .

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using the procedures of the ASTM melt index test method ; D-1238. The stress exponent i9 calculated using the ~ormula:

Stress exponent (S,E.) = 1 (wt extruded witth 6480 g wt 0.477 The stress exponent of a polymer is a measure of melt viscosity and is not a direct measure of molecular weight distribution. Stress exponent may be a ~unction of polymer molecular weight and it is preferred that the stress exponent values of different polymers be measured at similar levels of molecular weight or melt index whenever possible.
The film should have a thickness in the range of `
from 15 to 200Jum, preferably in the range of from 20 to 60 ~m.
The minimum amount of finely divided aluminum pigment which should be present in the film comprising the wrapping material of the present invent~on depends on the particle shape and the particle size distribution of the particular pigment being used. ~owever, the alumin~m pigment should be present in an amount of at least 0.1 g/m2 of film, The maximum amount of aluminum pigment which may be present in the film is governed by economic considerations and by the processability of the film in the film making process.
Preferably the aluminum pigment is present in an amount in the range of from 0.5 to 3.0 especially in the range of from o,8 to 1.5 g/m2 of film.
Optionally, inorganic lamellar filler partlcles such as mica particles may also be present in the film comprising the wrapping material of the present invention in order to improve the processability of the film on the packaging 3o machinery therefor and to make the film more paper-like in appearance, texture and the like~ The mica particles should ~ 0~3~3~
be present in an amount in the range of from 1.5 to 4.5 preferably in the range o~ from 2.0 to 3.5 g/m2 and should have a largest dimension (diameter) o~ less than 150~um.
Preferably the mica particles should have a weight median size of about 12 ~m with less than 0.2% by welght of the particles being larger than 44~um i.e., being retained on a 325 mesh (U.S. Sieve Series) screenO
As illustrated herelnafter~ the rate of - deterioration, as evidenced by peroxide build-up and taste deterioration, of butter and margarlne wrapped in the wrapping material of the present invention is much lower than the rate of deterioration of butter and margarine wrapped in (1) parchment, (2) unfilled and unpigmented high density - polyethylene, (3) TiO2 pigmented hlgh density polyethylene fllm, (4) mica fllled high density polyethylene film or (5) mica filled and TiO2 plgmented hlgh density polyethylene fllm, when each of the above packages ls stored in a brightly llluminated display case.
The wrapplng material of the present inventlon ls illustrated by the ~ollowing E~amples.
Three lots of fresh butter and three lots of freshly produced margarine were obtained and packaged in indlvidual small packages (21 + 0.2 g/package) made from twelve different wrapping materials; three packages of butter and three packages of margarine being made up from each wrapping material for each lot for a total of 216 packages.
Ten of the wrapping materials were high density polyethylene (HDPE) film materials of which eight were modified by the addition of a mica filler and/or a pigment. The other two wrapping materials were conventional butter parchment paper and aluminum foil wrap. The details of the high density polyethylene (HDPE) film materials are given below in Table I.

T.~

. . .
Pigment HDPEl- Film Mica Fil er2~ TiO2 Aluminum Film Thickness g/m~ by g/m % by g m Y
No. ~ m o~ film weight of welght of weigh film film . ._ . . .~ . ..
1 22.6 _ _ _ _ _ _ -

2 25.9 _ _ _ _ _ _

3 27.1 _ _ 1029 5 - _

4 32 2 _ _ 1.53 5 _ _ 27 9 2.64 10 _ _ _ _ 6 2206 2.13 10 _ _ _ _ 7 23.9 2.25 10 1.13 5 - - `
8 29.2 2.76 10 1,38 5 _ _ 9 2506 2,42 10 _ _ o.g7 4 10 - 31.2 2.96 ld - - 1.18 4 . . . . ~_ . _ _ . . ~ .

(1) made from a ethylene homopolymer having a density of o.~60 g/cm3, a MI of 0.75 decigrams/minute and a SoE~ 0~
1.8, ln a blown film process with a blow-up ratio of 4.4;
(2) wet ground mica having a weight median size of about 12 ~m with less than 0.2~ by weig~t of the particles being larger than 44 ~m i,e, being retained on a 325 mesh (U,S, Sieve Serie~) screen, was compounded ~rom a dry blend with the above ethylene homopolymer to a concentrate containing 40~ by weight mica. This concentrate was dry blended with - more of the ethylene homopolymer to the concentration indicated;
(3) TiO2 pigment available from the AMPACET* CORPORATION under the designation "whit,e concentrate No. 11,200" was made up --as a concentrate containing 70~ by weight TiO2 and then `
; dry blended with re of the ethylene homopolymer to the concentration indicated; and (4) CANBRO* 952 aluminum pigment was compounded from a dry blend with the above ethylene homopolymer to a concentrate containing 25% by weight aluminumO This concentrate was dry blended with more of the ethylene homopolymer to the concentration indicatedO
Table 1 indicates that only the small packages wrapped in HDPE film Nos. 9 and 10 were wrapped in wrapping material 4 according to the present invention as these were the only two of the ten HDPE film materials whlch contained aluminum pigment.
The packages of butter and margarine were exposed for a period of 12, 24 or 4~ hours to the light from two 40 watt cold-white fluorescent tubes mounted above an open refrigerated denotes trade mark

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display cabinet in whlch the temperature varied between 7 and 10C, The packages were placed 32.4 cm from the lights on a shelf mid way between the ends o~ the cabinet where the llght intenslty, as measured with a GE~ERAL ELECTRIC* light meter, Model 213, varied bet~een 275 and 300 foot candles~i.e.
between 2960 and 3230 lux or lumens/m2.) To minimize the effect o~ the position of the sample packages on the shelf, the positions of the sample packages during exposure were randomly selected for each trial.
After each exposure time, the entire contents of each sample package was transferred to a test tube and melted at approx. 60C. The samples were then thoroughly mixed and after fat-serum separation, 5 g aliquots were removed for duplicate Peroxide Value determinations made by the method given in the 11th edition of the "O~ficial Methods of Analysis of the Association of O~f~cial Analytical Chemists"
1970 pp. 445.
The peroxide values for the various package samples of butter and margarine are given below in Table 2 and Table 3, respectively.
Sensory analysis of the above butter and margarine samples was conducted by a panel of three experienced ~udges using the 9 point hedonic scale for scoring level of oxidlzed flavour as described by Larmond, Elizabeth in "Methods for Sensory Evaluation of Food", Canada Department of Agriculture, Publication 1284, 1970. In thls flavour scale, a numerlcal value of 1 represents no detectable oxidized flavour and a numerical value of g represents an extremely oxidized sample.
To overcome the problem of los~ of taste sensitivity due to 3o excessive coating of oral flavour buds with high fat product, 3% emulsions of the package samples in high quality skim milk were prepared and served to the ~udges ln the form of re-constituted milk.
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A summary of the test panel results for the various package samples for butte:r and margarine are given below in Table 4 and Table 5, respectively~
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films without aluminum pigment) on exposure to the same lighting conditions. Tables 4 and 5 indicate that under the same conditions the increase in the oxidized flavour values of the butter or margarine correlates with the increase in the peroxide values indicated in Tables 2 and 3. Thus the data in Tables 4 and 5 show the superiority of the wrapping materials of the present invention over parchment and the other HDPE film in protecting butter or margarine from light induced oxidized flavour.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A wrapping material for butter or margarine comprising a high density polyethylene film made from polyethylene having a density in the range of from 0.945 to 0.970 g/cm3 and containing finely divided aluminum pigment the aluminum pigment being present in an amount of at least 0.1 g/m2 of the film and the film having a thickness in the range of from 15 to 200 µm.

2. The wrapping material according to claim 1 wherein the aluminum pigment is present in an amount in the range of from 0.5 to 3.0 g/m2.

3. The wrapping material according to claim 2 wherein the film has a thickness in the range of from 20 to 60 µm.

4. The wrapping material according to claim 3 wherein the film also contains mica particles, the mica particles being present in an amount in the range of from 1.5 to 4.5 g/m2 of film, the largest dimension of the mica particles being less than 150 µm.

5. The wrapping material according to claim 4, wherein the average size of the mica particles is about 12 µm and less than 0.2% by weight of the mica particles are larger than 44 µm.

6. The wrapping material according to claim 5 wherein the film is a blown film having a thickness in the range of from 25 to 50 µm, the film is made from a polyethylene having a density of about 0.960 g/cm3, a melt flow index in the range of from 0.40 to 1.5 decigrams per minute and a stress exponent in the range of 1.6 to 2.0 and wherein the aluminum pigment is present in an amount in the range of 0.8 to 1.5 g/m2, and the mica particles are present in an amount in the range of 2.0 to 3.5 g/m2.

7. A package comprising butter or margarine wrapped in a high density polyethylene film made from polyethylene having a density in the range of from 0.945 to 0.970 g/cm3 and containing finely divided aluminum pigment the aluminum pigment being present in an amount of at least 0.1 g/m2 of the film and the film having a thickness in the range of from 15 to 200 µm.

8. A package according to claim 7 wherein the aluminum pigment is present in an amount in the range of from 0.5 to 300 g/m2.

9. A package according to claim 8 wherein the film has a thickness in the range of from 20 to 60 µ m.

10. A package according to claim 9 wherein the film also contains mica particles, the mica particles being present in an amount in the range of from 1.5 to 4.5 g/m2 of film, the largest dimension of the mica particles being less than 150 µm.

11. A package according to claim 10 wherein the average size of the mica particles is about 12 µm and less than 0.2% by weight of the mica particles are larger than 44 µm.

12. A package according to claim 11 wherein the film is a blown film having a thickness in the range of from 25 to 50 µm, the film is made from a polyethylene having a density of about 0.960 g/cm3, a melt flow index in the range of from 0.40 to 1.5 decigrams per minute and a stress exponent in the range of 1.6 to 2.0 and wherein the aluminum pigment is present in an amount in the range of 0.8 to 1.5 g/m2, and the mica particles are present in an amount in the range of 2.0 to 3.5 g/m2.