DE2016344A1 - Packaging with improved properties - Google Patents

Description

DR. BERG DIPL.-ING. STAPF

PATENT LAWYERS £ U | Q O H

8 MUNICH 2. HILBLESTRASSE 2O

Df. Berg Dipl.-Ing. Stapf, 8 Munich 2, HllblestraBe 20

30, AuVi

Your reference your letter Our reference date Attorney file 19 443

Monsanto Company
St. Louis (USA)

Packaging with improved properties

The present invention relates to a further embodiment of the packaging material according to patent application P 17 61 515.5.

The currently available synthetic polymers used in the production of packaging materials for food, Medicines and similar substances are used one or more serious drawbacks affecting their usefulness restrict for packaging purposes. Most eyn-

P « ■ Λό η, Λη 109813/1027

Case 8-12-0140, - ο _ ■

Synthetic polymers with good thermal deformation or processing properties are of a high degree Oxygen permeability and water vapor permeability, see above that foodstuffs and medicines packed in these materials from water gain or loss, oxidation, discoloration, Loss of taste, aroma, etc. »suffer, as a result of which they lose the interest of the consumer» vinylidene mixed

"polymers have sufficient oxygen impermeability, so that their use in certain food packaging is possible. However, the use of these materials is largely adjusted to film production because of difficulties in deforming such thick-walled objects appear. These vinylidene copolymers have poor heat sealing or sealing properties, but poor Drawing and stretching properties, low heat deformation temperatures and a low thermoforming sta-

) Mobility modulus and low strength, which are their general Severely restrict use. Other polymer systems, such as fully hydrolyzed polyvinyl alcohol, have Although they have a very high resistance to oxygen permeability, they have serious disadvantages in this respect they are water sensitive and have a very high water vapor transmission rate exhibit. Furthermore, these polyvinyl alcohol polymers lose their excellent properties Resistance to oxygen permeability under conditions of high humidity and generally have

-3- 10 9 8 13/1027

2Q16344

- 3 mean bad processing properties *

There is, therefore, a marked shortage of packaging materials for food and medicines in the form of containers formed by thermoplastic resins, which have both high resistance to oxygen permeability and low water vapor permeability, as well as improved process and physical properties, see above that the containers can have different shapes and sizes and can be produced as blow-molded or injection-molded bottles, thermoformed containers made of sheets or foils, etc. _c

The desired degree of oxygen impermeability and water vapor permeability (WDD) in a packaging material can vary for the particular food or medicament to be packaged and under the given storage conditions, e.g. B ». by temperature, humidity, ventilation, type of light and its intensity, etc. "In general, more critical conditions call for a material with an oxygen permeability below 1 cm / 100 cm / 24 hours, thickness 0.0254 mm, 1 atm", pressure at 23 ° C and a WVTR of less than 1.3 g / 24.Std _o / i00 cm ^2, 0.0254 mm in thickness at 38 ⁰ g 95 and #iger relative humidity.

These critical requirements are in the essay "Modern

10 9 8 13/1027 -

2 O Ί 6 3 A 4

Packaging ", March 1965," Flexible-Vacuum Performance ", page 201 ff explained, where the extreme sensitivity of coffee to moisture and oxygen is listed. The authors of this article state that an increase in the moisture content of coffee of about 1 fo, do ho from about 1.4 to 2.6 #, a bowl, thread

May cause taste after 20 days, while only 15 cm Oxygen can cause half a kilo of coffee to taste stale.

Dairy and meat products and some pharmaceuticals are equally, if not more, sensitive to oxygen and moisture than coffee and in some cases require packaging materials with even more greater impermeability to oxygen and water vapor than is required for coffee packaging,

This invention relates to packaging for food and medicaments which meet these more critical packaging conditions demand"

It is therefore an object of this invention to provide new packaging for food, medicine and similar items to create, for which purpose the packaging is made of resins that are both highly resistant to Oxygen permeability and low water vapor permeability as well as improved procedural and physical

-5- 109813/1027

2Ü16344

"5 characteristics exhibit·", .

Another specific subject is that so " before packaging is made available, whereby- man Containers used made from the molten resin underneath solvent-free conditions are formed «.

The above and other objects are obtained by using packaging for foodstuffs. Medika "elements and other © corresponding noun ^ * creates ¹² ^. ,, what a'thermoplastischen-the deformed container. Resin; gebil ^ det, which as' 1 cmVlOQ ² / 24h h "1 atm" pressure strength Q, Q254 mm at 23 ^ G and has $ 5 ⁰ ^ relative Eeuehtigkeit * The resin ent maintains an oxygen permeability of less em "(A ) 75 to 1QQ & e.w _ft Te.ile. Mixed polymer which is formed as a polymerization product of AlQi'yliaitril and little else. EiRem Öomofnomer from V'in ^ lestern and / eder Vinylä, thtern _r "of the same ^^ (b) Q to 25 Geji ,, £ e, il§ |> ^ d _u iEt on §in VQrgefo, rnte, .s, Jfiutsehuksub «

emt8pr © ehe, nd 45 big IO flows from the Wed (A) Qben guagtwähliien; Qmam®m®m% & q. da® its Sarz, a rvlaitrile content of 55 to. i © G | e, Where? l shows «is durah; fQym: p, i »@ s, s§nd © 8 tm · westatli.eifeeii löesungsittitttl
fgrinea einer] & att9 §4tP f © lie formed! the _; the end. 4em

i 100613/1027

2U16344

-S-

The component responsible for the improved barrier properties as described in this invention is acrylonitrile, which must be present in an amount of at least 55% by weight of the total resin weight. This is necessary to obtain a water vapor permeability that is less than 1.3 g / 24 h _e / 1ü0cm, thickness 0.0254 mm at 38 ⁰ O 95 $ relative humidity and an oxygen permeability of less than 1 cm / 100 cm / 24 hours "1 atm" pressure, thickness 0.0254 mm at 23 ° 0 to be achieved "These behavior values are the maximum limits that can be tolerated when used in areas that require critical barrier properties when degradation, oxidation or taste and / or a loss of flavor of the product should be prevented »Especially within this range, packaging materials with correspondingly lower oxygen permeability and water permeability are required for certain products than in others.

The percentage by weight of acrylonitrile used in the copolymers of this invention is in the range of 55 to 90 wt. #, With a range from 60 to 85 wt. # Particularly preferred is »Copolymers with an acrylonitrile content of 65 bia are particularly preferred

The lower limit of 55 weight "# acrylonitrile weeentlieh when the packaging material is to be used for the above-mentioned kriti-8oneη packaging purposes · The upper

100813/1027 " ⁷ "

-. . 2U163U

The limit of $ 90 is critical in order to maintain the low water vapor transmission rate and to produce a resin that is easy to process in bottles, containers, foils and the like under solvent-free conditions wt <> $ approaches, it becomes extremely difficult, the polymer molding of bulky objects (eg ₀ B * of bottles, containers, sheets or films, etc.) to give processed in conventional plastic devices "Thin films of polymers which more than 90% acrylonitrile are most conveniently made by solvent casting processes (dipping processes) which are not easily or economically suitable for the formation of bulky objects. Resins higher than 90% acrylonitrile after heating to about 220 ° retain sufficient crystallinity to substantially preclude flow. When the acrylonitrile to even higher temperatures, is heated (about 285 0) than is required to melt the crystalline Acrylnitrilketten decomposed 'the polymer, which can be recognized quickly by discoloration and reduced solubility in dimethylformamide, dimethylacetamide, etc. _o. It therefore severely restricts the physical properties (including the polymers which have a greater than 90 "/ algae acrylonitrile content) the thermal molding of bulky objects and only allow the solvent casting of thin films« -8- ^; 10 9 8 13/1027.; ,,

However, the presence of at least one vinyl ester and / or vinyl ether gomonomer in the acrylonitrile resins prevents it of this invention either the long rows of the acrylonitrile arrangement, which lets the crystallinity arise, or it reduces the crystal size and complete formation » This gives a polymer with a lower melting temperature range and good flow behavior at lower ones Temperatures ,,

As a result, the resins not only have good barrier properties, but they also have the critical properties that allow them to be easily molded into the shape of a sheet material for thermal deformation and for injection or blow molding in bottles and other molded articles _o The containers obtained correspond to the critical packaging requirements for the purposes envisaged here.

The balance of the polymer is formed from one or more vinyl ester and / or vinyl ether monomers with Acrylonitriles are copolymerizable, although small amounts (less than $ 10) of one or more others Ethylenically unsaturated monomers can be included in the copolymers.

The vinyl ester monomers have the following general formula: BAD

-9- 109813/1027

H
ι

H ₀ G s = O

O
ι

C = O
ι

Ε,

wherein R ^ is hydrogen, alkyl groups of 6 to 10 carbon atoms including the carbon atoms in the ring is substituted alkyl substituents, Zo Bo vinyl formate, vinyl acetate, Vinyl propionate, vinyl benzoate and the like.

The vinyl ether monomers have the general formula: HpG = OH .- O - R., where R. is an alkyl group with 1 to 8 carbon atoms, an aryl group with from 6 to 10 carbon atoms or a monovalent aliphatic radical with from 2 to 10 carbon atoms, where the aliphatic radical can contain hydrocarbons or oxygen, i.e. ₀ h. is an aliphatic radical with ether bonds and can also "contain other substituents such as halogen, carbonyl, etc." Examples of these monomeric vinyl ethers include vinyl methyl ether, vinyl ethyl ether, vinyl n-butyl ether, vinyl 2-chloroethyl ether, vinylphenyl ether, vinyl isobutyl ether, vinyl cyclohexyl ether, p-butylcyclohexyl ether, vinyl ether or p-chlorophenyl glycol, etc.

This invention also includes the use of a synthetic one or natural rubber component on which

- ^v ·· ■ '-ιο

ί 09813/1027

- ίο -

the aeryl nitrile copolymer can be grafted. Preformed rubber substrates include polybutadiene, Isoprene, neoprene, nitrile rubbers, natural rubbers, other conjugated diene elastomers, butadiene copolymers, Ethylene-propylene copolymers, chlorinated rubbers, etc., which are used to strengthen or toughen the after Packaging materials made of this invention are used. The preferred substrates are diene rubber and, particularly desirable, homopolymers of butadiene or copolymers of the same with aromatic monovinylidene Hydrocarbons and ethylenically unsaturated nitriles, such as butadiene / acrylonitrile, butadiene / styrene and butadiene / styrene / acrylonitrile Polymer mixtures obtained by mixing a graft copolymer are particularly preferred of the acrylonitrile and the oomonomer on the rubber skeleton with a matrix copolymer of acrylonitrile and the same comonomer as used in grafting will receive "

The acrylonitrile copolymers and the graft polymers of this invention can be prepared according to any one known to those skilled in the art Processes can be produced, e.g. by bulk polymerization and by emulsion, solution and suspension polymerisa tion process »They can be produced at atmospheric, subatmospheric or superatmospheric pressures will.

10 9 8 13/1027

■ 2Ü163U

The films or sheets produced from the aforementioned resins can be produced by extrusion, pressing, calendering, casting or by other methods known to the person skilled in the art. Thereafter, the film is or _o plate to the desired container shape pressed or deformed, usually by heat in a conventional und_Druck Thermoformarbeitsverfahreno bottles and containers can be prepared by any conventional method such as by blow extrusion, transfer molding are prepared uswo "

The invention also includes the use of conventional ones

Additives such as dyes, fillers, pigments, plasticizers, stabilizers, etc. in the packaging materials of these Invention.

The following examples serve to explain the invention and are not intended to restrict the inventive concept «, All parts and percentages are by weight unless otherwise indicated.

example 1

This control example serves to determine the test methods used and show the poor results obtained when using an acrylonitrile (AlT) Polymer used, which is less than 55 wt. # Contains acrylonitrile.

-12-10 9 8 13/1027.

2 ü 1 b 3 4 4

100 g styrene / acrylonitrile (SAN) copolymer with an acrylonitrile content of 26% by weight is "pressed" at 266 ⁰ O (510 ⁰ F) and approx. 700 atm (10,000 psi) for 30 seconds with the formation of a clear, transparent film of 0.127 mm ( 5 mils) thickness »This film was cut into rectangular sections and tested for oxygen permeability in a" Dow Gell "according to ASTM method D 1434-63 and for its water vapor transmission rate (WDD) according to ASTM method E 96-63T. The following results will get:

WDD at 38 ⁰ G and 95 # relative humidity 1.87 g / 24 hours / 100 cm ² at 0.0214 mm thickness;

Oxygen permeability at 23O ⁰ G 5.6 cm ⁵ / i00 cm ² / 24h STDO at 0.0254 mm thickness and 1 atm "pressure.

These values are significantly above the maximum level for more critical packaging purposes can be tolerated »The As will be shown below, higher values are attributable to the fact that they are insufficient Acrylonitrile was used in the polymer preparation »

The WDD speed is given in grams of water that penetrates a film with a thickness of 0.0254 mm and

an area of 100 cm in a 24-hour Zeiträum, wherein the ambient conditions at 38 ⁰ G and 95 relative #iger

-13- 109813/1027

2Ü16344

Moisture must be kept * The rate of oxygen permeability is given in cubic centimeters of oxygen that penetrates a film with a thickness of

2
0.0254 mm and an area of 100 cm during a 24-hour period under the pressure conditions of 1 atmosphere (760 mm) of oxygen at 25, ⁰ Co ..

The results in Table 1 explain the inferior water and / or oxygen permeability compared to other known multi-pack materials which do not contain acrylonitrile. These results also reveal the completely unexpected, superior results that are achieved when ■■ - one uses the polymers of this invention which contain from 55 to G-ew.fS acrylonitrile «

Table 1

WDD and oxygen permeability for copolymers, which do not contain acrylonitrile

Polymer "WDD ^V 'Oxygen- _______ Permeability ^ ^ ^}

Polystyrene (oriented) 1.45 50.6

Polystyrene (not oriented) - 60.5

High density polyethylene 0.15 79.2

Low density polyethylene 0.2 79.0

^ -Methylpentene / ^ - methylbutene ^ 1.0 450.2

Polyvinyl chloride. 0.42 1.6 Polypropylene (biaxial orient) - 21.7 Polycarbonate - 20.9

109813/1027

-H-

^ ¹ ^ Me WDD values are here in g / 24 hours / 100 cm ² at 0.0254 mm thickness, "at 38 ⁰ G and 95% relative

Humidity indicated;
^v ' The oxygen permeability values are here in cnr / 100 cm / 24 hours, 1 atmosphere Brück at 0.0254 mm

Strength and 23 ⁰ C indicated?
^ 'Prepared using an 85/15 mole. # Monomer feed ratio.

Example 2

The unexpected decrease in WDD when using polymers which contain 55 to 90% by weight of acrylonitrile is explained in Table 2 below, wherein the WDD for styrene / acrylonitrile polymers below as a function of the content of acrylonitrile in weight is shown

Table 2 WDD ^ WDD by SAN copolymers 2.95 Wt. # Styrene Weight £ AN 4.18 100 - 4.95 90 10 5.75 80 20th 3.40 60 40 2.47 51 49 1.70 40 60 30th 70

109813/1027 " ¹⁵ ~

2ü16344

^ 'Measured "at 49 ° G and 95 ° relative humidity Values in g / 24 hours / 100 cm ² ,. Thickness 0.0254 mm"

A graph of the WDD versus the content of acrylonitrile in weight percent shows that the WDD increases to a maximum value at 35 to 40 weight percent acrylonitrile . Acrylonitrile is approaching 90. A homopolymer of polyacrylonitrile is of no interest despite similar barrier properties because such a homopolymer cannot be produced from the melt; the flow temperature is higher than the decomposition temperature. The only known way to process polyacrylonitrile is! Recast "or extruding from the solution ₀ This not only makes the use of suitable solvent systems are required which are expensive at best and un- 'hand lent and create further toxic problems, but it is also impracticable to form any article other than thin sheets from solvent casting, which makes the manufacture of articles in certain shapes such as bottles impossible, but which is an essential and crucial part of this invention Extraction of the solvent for an extended period.

■ -16- - 1098 13/1027 /.

2ü1b3U

Example 3

A copolymer of 75% acrylonitrile and 25 ° vinyl acetate is made by an emulsion polymerization process. A compression molded film is made and tested in a manner similar to Example 1. The water vapor permeability at 38 ⁰ G i and 95 ° relative humidity is 0.16 g / cm ² at 24 Std./iOO 0.0254 mm thickness and the oxygen permeability at 23 ° C is 0.23 cm ⁵ / i00 cm ^2/24 Std ", 1 atmosphere, 0.0254 strength, these values are within the desired ranges for the packages of the present invention.

Example 4

A copolymer of 85 $ acrylonitrile and 15 i ° vinyl ethyl ether is produced by an emulsion polymerization process. A compression molded film is prepared and tested in a manner similar to Example 1. The water vapor permeability at 38 ⁰ C and 95 ° i relative humidity is 0.23 g / cm ² at 24 Std./iOO 0.0254 mm thickness and the oxygen permeability at 23 ° G is 0.16 cnr / 100 cm ² / 24o STDO , 1 atmosphere, 0.0254 strength, which are within the desired ranges for the packages of the present invention.

Example 5

This example illustrates the manufacture of bottles that

-17-109813 / 1H27

2Ü16344

for packaging food, medicines and the like Substances are used.

4 oz. "Boston Round" bottles are made using the same polymers used as films in Examples 3 and 4 230 to 260 ⁰ O ' ■ (450-500 ⁰ F), and bottles with an average wall thickness of 0.508 mm are obtained. Gas chromatographic tests show that these bottles have desirably high oxygen barrier properties

Example 6

A graft polymer mixture is produced by means of an aqueous emulsion process which contained 600 parts of water and 2 parts of soap (rubber reserve S) as an emulsifier with 1.0 part of KaHumpersulfate as a catalyst »The reactants contain 100 parts of butadiene / acrylonitrile (70/30) Rubber substrate and 200 parts of acrylonitrile / vinyl acetate monomer mixture (75/25) · After polymerizing for nine hours at approximately 75 ⁰ O, the resulting graft polymerization product is coagulated, washed and dried.

It can be seen that the present invention provides packaging for food, medicine and the like, where this is essentially compared to degradation by oxygen permeation

-18- 109813/1027

2U16344

meability and water vapor transmission through the container wall »The containers can be made relatively economical and easy using conventional molding techniques from molten resin or by thermoforming processes made of sheets made of the molten resin.

-19-109813 / 1027

Claims (4)

Claims 1. Further training of the packaging material according to patent application P 17 61 515-5 for food or drugs, which are completely in a (press) molded container made of a resin that has an oxygen permeability of less than 1.01 cm ^5/100 cm ^2/24 hr., J atmosphere, 0.0254 mm in thickness at 23 ° C and a water vapor permeability of less than 1.31 g / 24 hr., 100 cm ^2, 0.0254 mm in thickness at 38 ° C and 95 $ relative humidity, characterized in that a resin is used which contains (A) 75 to 100 parts by weight of copolymer formed as a polymerization product of an acrylonitrile and at least one further comonomer of vinyl esters and / or vinyl ethers and (B) 0 to about 25 parts by weight of the product of the graft polymerization onto a preformed rubber substrate of a monomer mixture of 55 to 90% by weight of acrylonitrile and correspondingly 45 to 100% by weight of comonomer selected from the copolymer of (A), the Resin has a total acrylonitrile content of 55 to 90 wt. £ , the container is formed by compression molding of the molten interpolymer under essentially solvent-free conditions or by forming a film from the molten interpolymer under essentially solvent-free conditions. - 20 109813/1027 - «ι- 2Ü163U 2. Packaging material according to claim 1, characterized in that the resin contains 5 'to 25 wt. I »graft polymerization product. 3. Packaging material according to claim 1, characterized in that the preformed rubber substrate is a copolymer of butadiene and acrylonitrile. 4. Packaging material according to claim 1, characterized in that the comonomer is vinyl acetate. BAD ORiGiNAL 109813/1027