DE1569337A1 - Packaging material and coating compounds for application to such - Google Patents

Description

OR-ING. DIPL.-INC M. SC. DIPL.-PHYS. DR. 'DIPL.-PHY9.

HÖGER - LEGAL RIGHT- GRIESSBACH - HAECKER

PATENT LAWYERS IN STUTTGART

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(submitted! t g? m. Article 7.771, Paragraph 2, No. of the Anclenrngsgasötzes)

Riegel Paper Corporation 260 Madison Avenue New York, N.Y., USA

Packaging material and coating compounds for application to such

The invention relates to coating mixtures for on · * · application to various substrates such as glassine, kraft paper and various films, particularly to a new and improved coating mix with an optium, are desirable Properties, especially what is hereafter referred to as water vapor insulation designated resistance to water vapor transmission, Heat sealability and suitability for packaging food products. The invention is concerned

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also with a packaging material that is made of a suitable Substrate and a coating made of the mixture according to the invention.

For example, when packaging food products, it is often important that the packaging material be prescribed Has barrier properties with regard to the passage of water vapor and gas in both directions. Additionally If possible, the packaging material should also be able to close by a heat sealing process in which a durable seal will expand for a reasonable amount of time Range of working conditions encountered in the various packaging machines during normal manufacturing processes results. For the packaging industry, other properties are also desired, such as a good looking one Surface, resistance to abrasion and sticking, sufficient flexibility, the ability to use pigments to include, etc. Various packaging materials currently on the market probably have some of the ones in the case of one ideal packaging material, but are completely inadequate in other respects. It was particular difficult to achieve the desired moisture impermeability and heat sealability in one relatively To combine materials that can be produced cheaply without adding components, which in turn are used for the packaging of foodstuffs were undesirable. . /

According to the invention, a new and improved composition for use with a packaging material substrate is provided intended, which is particularly suitable for the packaging of food and the best possible properties in terms of

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Heat sealing and water vapor insulation. Furthermore is the mixture according to the invention by its effective barrier properties against gas, their attractive appearance, their resistance to abrasion and sticking, their flexibility, characterized by their easy pigment absorption capacity and other features that are desirable for a packaging material. the The invention is concerned not only with the coating mixture itself, but also with a packaging material composed of certain substrates and a coating mixture, of which from Glassine substrates are the most important. ·

Insbesondert contains the coating mixture according to the invention as the main film-forming constituent ₅ cyclized rubber, preferably natural rubber sykllsierten. The cyclized rubber, the proportion of which is advantageously about 50 % of the new mixture, is modified by the addition of wax, which results in improved water vapor insulation, and furthermore by the addition of a vinyl polymer or a similar modifier that improves the heat-sealing properties In a particularly advantageous composition, the wax modifier is about 25% and the heat seal modifier is about 30 % of the mixture, although these numbers can of course vary depending on the properties of the particular modifiers used. (The details in jf or in parts of components mean weight Ji or weight parts, unless expressly otherwise avoided. )

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. A glassine substrate coated with the mixture according to the invention exhibited strikingly superior water vapor insulation and gas barrier properties and at the same time resulted in extremely low coating weight a seal so reliable that it tears the fibers of the substrate rather than the The seal is breaking. Such a good seal is referred to below as a Paser tear heat seal. These basic properties together with other desirable features make the mixture according to the invention for packaging of foods particularly suitable and beneficial.

In a preferred embodiment according to the invention the main component of the mixture is a cyclized natural rubber. Advantageously, this cyclized rubber is a hard, tough, horn-like, polymeric resin with an average molecular weight between about 500 to 10,000, a melting point of about 145-155 ° C. (ball-and-ring method), a density of 1.0 at 25 ° C, a refractive index of 1.535 at 25 ° C and with the color "M ¹ '(USDA rosin scale).

For the production of mixtures according to the invention, cyclized synthetic rubbers were also used, which gave a satisfactory result, but phenol-cyclized natural rubber is preferred. The cyclized rubber content of the blend can vary between about .10 and 80S », and within these limits the results are still satisfactory. Much better water vapor insulation properties are achieved, however, if you keep within the limits of about 25ί and about with cyclized rubber .

009813/1786 ^ß * D original

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One of the most important modifiers used in the mixture of the invention is wax. In a special, preferred mixture, this wax is a paraffin with a melting point between approx. 57 ° and 60 ° C., which is sold by the Sun Oil Company under the name Sun 4312 paraffin wax. Microwax and vegetable wax can also be used with acceptable results, but paraffin wax is preferred because of its superior water vapor barrier properties. Waxes with a melting point lower than the aforementioned range will probably improve the water vapor insulation properties, but they will reduce the resistance of the mixture to sticking together. ⁺ / On the other hand, higher melting point ranges improve the resistance to sticking together, but reduce the water vapor insulation properties, especially in the case of coated substrates in the folded state. So while the particular wax can be selected depending on the intended use, the above wax gives an optimum of properties for general use.

A second, important modifier, which is used in the new mixture according to the invention, enables this Heat sealing. The most beneficial group of heat seal modifiers are vinyl polymers and vinyl copolymers, although there are other heat-sealable compositions that are compatible with the other • materials

+) A coated substrate has good barrier properties if two foils for 24 hours at approx. 49 C under one pressure of approx. Ο.Ο23 kg / cm and then at Dismantling no tendency to cake or clog

. ^: show sticking together.

BAD ORIGINAL 0 0 S 8 1 3/1 7 S 8

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. were used. Arguably the most beneficial specialty heat seal modifier is a vinyl acetate-ethylene copolymer manufactured by EI du Pont de Nemours & Co., Inc. under the tradename Elvax 250. Experiments have shown that the heat seal modifier can be used in the new blend in amounts between about 3 and 65Ji; although optimal results appear to be around 30 % .

In addition to the above-mentioned main components of the new mixture, it is desirable in certain cases to add smaller amounts of additional substances, such as anti-oxidation substances, substances for the absorption of ultraviolet rays, pigments, substances that beautify the surface, release agents that facilitate shaping, etc. The basic composition seems to be the same tolerate a large number of such smaller amounts of additives. Suitable anti-oxidation substances are preparations made from butylated hydroxytoluene or butylated hydroxyanisole. A small amount (for example 1 - 3 %) is sufficient for normalerväse. For packs not intended for foodstuffs, an adsorbent for ultraviolet rays such as Uvinol 400 can be used instead of or together with an anti-oxidant substance.

The mixture according to the invention is easily applied to one or both surfaces in a form dissolved in a solvent of the desired substrate, a coherent, solid film forming after evaporation of the solvent

ORiQiNAL

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forms. The usual aromatic hydrocarbons (for example benzene or toluene) have proven to be suitable solvents, and naphtha can also be used in cases where this appears expedient. Usually such a solution contains 70-80% solvent.

In a typical application, a glassine substrate of " about 13 »6 kg basic weight coated on both sides with about 0.68 to about 1.36 kg per ream 4 · +). It will come not on particularly good water vapor insulation properties, so the amount of the coating layer can also be smaller. It fiber tear seals can still be provided with coating layers

produce a weight of less than 0.272 kg per ream. Nevertheless, a better lower limit for commercial processing is around 0.68 kg per ream.

To the respective properties determine a plurality of Heißversiegel-modifying agents, there was prepared a particularly advantageous novel composition and coated in coating layers of 1.22 to I ₁ ¹ JO kg per ream weight on both sides of a 13.60 kg heavy Pergaminsubstrates. The heat seal modifier used in each case was changed in the same amount, and measurements were made to determine the water vapor insulation and heat seal properties. The composition and test results are shown in Table I below.

+ ♦) 1 ream = approx. 279 m

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Table I.

Composition: cyclized rubber

Sun 4312 paraffin wax (melting point 60 C)

Heat seal modifier (see below)

Heat seal modifiers

Water vapor insulation properties 46 % 25 %

29 %

Heat sealing properties

XYHL · Polyynyl-butyral manufactured by Union Carbide Co.

AYAP polyvinyl acetate (softening point 77 C) by Union Carbide Co.

AYAT polyvinyl acetate (softening point 87.5 C) by Union Carbide Co.

Elvax 250 vinyl acetate-ethylene copolymer (28 % vinyl acetate) manufactured by EI du Pont de Nemours & Co., Inc.

Elvax 150 vinyl acetate-ethylene copolymer (33 % vinyl acetate), manufactured by EI

du Pont de Nemours & Co., Inc.

Elvax 3602 vinyl acetate-ethylene copolymer (40 % vinyl acetate) manufactured by EI du Pont de Nemours & Co., Inc.

Vinylit VMCH vinyl acetate

Vinyl chloride copolymer (13 % vinyl acetate) manufactured by Union Carbide Co.

Vinylit VAGH vinyl acetate-vinyl chloride mixed polymer (3 % vinyl acetate) manufactured by Union Carbide Co.

Estergurami 8-L glycerine ester made from rosin resin by Hercules Powder Co.

0.04 0.68 0.40

0.05 0.04 0.01 0.28

0.40 0.15 good
Well

sufficient to good

excellent

excellent

excellent

see you well

see you well

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Dow 276 V-2 poly-alpha-methyl styrene manufactured by
Dow Chemical Co.

0.13

(extremely shiny surface)

+++) The water vapor insulation properties were determined according to the method of the Technical Association of the Pulp and Paper Industries T 464 M-45 and are given in units of 100 square inches per 24 hours at a relative humidity of 95 % and approx. 36 C. . All numbers relate to flat films, unless folded films are expressly mentioned.

++++) The heat seal grades are determined as follows:

Excellent: Makes a tear-off seal on paper

including a wide temperature range of 76 to 177 ° C. Sealing after a short contact time and low contact pressure, resulting in a good execution with equipment operating at high speed. Has the ability to 15 g / 2.54 cm To bear the load at sealing temperatures. Requires a top coat weighing 453 g / ream or less to get a fiber tear seal on uncoated glassine paper.

Excellent: Has the same properties as under "excellent" listed with the exception that the ability to carry a load at sealing temperatures is only 5-14 g / 2.54 cm.

Good: Has the same properties as listed under "excellent" except that it is at sealing temperatures cannot bear a load.

Sufficient: The seals produced do not tear fibers immediately moderately. Such seals are commercially available under the reference known as "blotchy seals".

or

Produce firm, uniform seals but do not tear off fibers.

or

Need more than 453 grams per ream to make it more effective Seal.

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As must be assumed, the following commercially available preparations (in addition to other vinyl, acrylic, styrene polymers and copolymers and other rosin esters and other resins derived from wood) are also useful as heat seal modifiers: polyisobutyl methacrylate manufactured by EI du Pont de Nemours & Co., Inc. under the tradename Lucite 45; Aeryl-at-ethylene copolymers manufactured by Union Carbide Co. under the trade names Bakelite DQ DA2100 and Bakelite DQ DA327O; Vinyl acetate-vinyl chloride copolymer (13 % vinyl acetate), "manufactured by Union Carbide Co. under the trade name VYHH; vinyl acetate-ethylene mixed polymer (18 % vinyl acetate), manufactured by EI * du Pont de Nemours 4 Co., Inc., under the tradenames Elvax 420 and Elvax 460; vinyl acetate polymer manufactured by Union Carbide Co. under the tradename AYAP, and also low molecular weight polyethylene such as that made by Allied Chemical Corp. is manufactured under the trade name AC-6.

About optimal proportions between the wax and the cyclized gum ingredients and the heat seal modifiers A series of experiments were made to obtain 100 parts of cyclized rubber, 63.6 parts of Elvax 250 and zero ^ -

to 327 parts of Sun 4312 paraffin wax was used. The .. ~ j. various mixtures were applied on both surfaces of a £ s 13.60 kg heavy Pergaminsubstrates, wherein the weight of the coating layers per side between 1.08 and I ₇ was 45 kg per ream. The heat seal and water vapor barrier properties achieved in each case were measured and are shown in Table II below. /

009813/1786 _OA ■

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cyclical

more

rubber

Elvax 250 (parts per 100

Wax parts)

Table II

Sun 4312 araffin-

ffachs

(Parts per 100

compartment parts)

Heat seal
Property
th
++++) water
steam -
damm-
mingling
Own
sheep-
th
+++) emerged
outstanding
emerged
outstanding 6.22
5.99 emerged
outstanding 1.42 out
draws O.il9 out
draws 0.10 out
draws 0.0.2 out
draws 0.02 out
draws
Well 0.02
0.02 Well 0.02 sufficient 0.02 sufficient 0.03 sufficient 0.03

About ugs weight kg

.100

• 100

.100

100

100

100

100

8th 100 9 100 10 100 11 100 12th 100 13th 100

63.6 63.6

63.6 63.6

63.6 63.6 63.6

63.6 63.6 63.6 63.6 63.6

63.6

9.1 18.2 27.2 36.4

I5.5 54.6

72.8 9I.O 121.0 182.0 236.O 327.O 1.36 1.09

I.38 1.43

1.29 1.18

1.27 l.ilO 1.38 1.40

.1.38

1.45

Explanation see page

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From the table above it can be seen that the hot. Sealing properties change inversely proportional to the amount of paraffin wax used, while the water vapor insulation properties change proportionally to the amount of wax. Extremely satisfactory results can be achieved when the amount of paraffin wax is between 36 and about 73 % , since all coated substrates within this range have "excellent" heat sealing properties and water vapor insulation values of less than 0.10. However, depending on the intended use, compositions would also be suitable which contain smaller or larger amounts of wax. In certain cases, in which the heat-sealing properties are not of particular importance, it could be advantageous to use larger amounts of paraffin wax in view of the low cost of this component. Even in a mixture using 327 parts wax per 100 parts cyclized rubber and 63 x 6 parts Elvax 250, the heat seal properties are reported as "sufficient", indicating that the seal is well suited for a wide range of applications.

A glassine substrate coated on both sides according to No. 6 of Table II exhibited superior gas barrier properties. For example, the coated glassine had an oxygen transmission rate of about 0.03 (approx. 1 atm., At 23 ° C and 0 Jl! Humidity) compared to cellophane coated with polyvinylidene chloride (at 35 % relative humidity), which has a permeability value between 0.5 and 1.5.

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Where extremely good heat sealing properties are desired -and the water-damping insulation properties are less important are, the amount of wax can be reduced accordingly, and a composition of, for example, 100 parts cyclized Rubber, 63.6 parts Elvax 250 and 18.2 parts wax, which is applied to typical fibrous substrates (e.g. glassine) results in a fiber tear seal with the coating layer is extremely light.

Using a constant, average amount of paraffin wax, a series of experiments were carried out in which the ratio between cyclized rubber and heat seal modifier was changed. The various test results are shown in Table III below.

Table III

cyclical Elvax Sun 4312 Heat seal Steam Coating more 250 paraffin properties insulating weight rubber % wax Property kg % % ten +++) • 1 66.7 8.3 25th Well 0.11 1.31 2 58.3 16.7 25th excellent 0.02 1.24 net 3 54.0 21.0 25th excellent 0.01 1.43 net 4th 37-5 17.5 25th excellent 0.09 1.49 net 5 29.0 46.0 25th excellent 0.25 1.40 net 6th 21.0 54.0 25th Well 1.17 1.Ä0 7th 12.5 62.5 25th Well 1.92. 1.40

^ For an explanation, see page 9

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The numbers reported in Table III show that acceptable heat seal properties can be achieved over a wide range of cyclized rubber to Elvax ratios while maintaining the wax content constant at 25 % .

At the lower limits of the cyclized rubber ingredient, it was possible to keep the water vapor barrier properties within the desired low levels by increasing the amount of wax significantly. This was probably done at the expense of the heat-sealing properties, but even with a wax content of 65 % an acceptable heat seal was produced which was far superior to that which would have been achieved, for example, with ordinary wax or with wax modified with a vinyl acetate-ethylene copolymer can be achieved.

A particularly beneficial mixture for general use apparently using 100 parts of cyclized rubber, 63 x 6 parts of Elvax 3602, manufactured by E.I. du Pont de Nemours & Co., Inc., and 54.6 parts of Sun 4312 paraffin wax. The effect of one such coating on a variety of substrates was determined by applying about 1.22 to 1.36 kg per side per ream for different substrates, wherein the adhesion of the mixture to the substrate, the water vapor insulation and the heat sealing properties as well the transparency were determined. These results are shown in Table IV.

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Table IV

Substrate adhesion water
steam -
insulating
Own
stocks
+++) Heat seal
properties
++++) Through
activity • Glassine very good 0.02 excellent
net bleached
Kraft paper
first qua
lity very good O.I9 excellent
net
* very good bleached
Kraft paper
lower
quality very good · 0.13 excellent
net very good PT cellophane very good 0.01 excellent very good Mylar
(Polyester) Well - Well very good Polyethylene very good - Well Polypropylene very good - Well very good aluminum
foil very good - - Well very good cellulose
acetate film - * _ - sufficient . Polycarbonate
Movie bad up
sufficient

Films made of polystyrene, nylon, saran and polytetrafluoroethylene may be mentioned as further examples of satisfactory substrates.

To conform to the heat seal characteristics of a typical mixture Determining the invention were different weights

For an explanation, see page 9

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of a given composition is applied to a bleached kraft paper substrate. The composition consisted of 100 parts of cyclized rubber, 63 parts of Elvax 3602 and 54.5 parts of Sun 4312 paraffin wax. With a typical weight of the coating layer of I _x j #> kg per side per ream, fiber tear seals were produced at heat sealing temperatures between 71 and over 190 ° C. At temperatures above 93 ° C, the minimum contact time is less than 1/2 second, and experimentally ¹ seal was achieved by using contact press up to Ο, 4218 kg / cm (which is the lower limit of the experimental equipment). A heat seal was particularly good. A bleached Kraft paper substrate, which was coated at 1.36 kg per side per ream, was able to carry 25 g / 2.54 cm at 107 ° C. after sealing the cover side with the cover side. In addition, tear seals with coating weights as low as 0.272 kg per side per ream were achieved.

When the mixture according to the invention is applied to a suitable packaging material substrate such as glassine, the result is a packaging material with excellent water vapor insulation and heat sealing properties in addition to other characteristics which make the material very desirable for packaging foodstuffs and other applications. While Paser tear heat seals result, water vapor insulation values of 0.01 can be achieved with the new material when the material is flat and 0.12 when the material is folded. In this context, _se i pointed out that ten times higher levels of water vapor Dämmungs would be considered good in flat condition from a commercial standpoint still be extremely than the foregoing. To give an example, the commercially available ones often used for packaging have a polymer

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coated cellophane films have water vapor insulation values of 0.7j and these are about seventy times as high as those with a Mixture according to the invention achieved optimal water vapor insulation values. In addition, with the mixture according to the invention, it is still possible to achieve well below 0.1 ("extraordinary good ") achieve water vapor insulation values (together with Paser tear heat seals) under production conditions, which is less than 1.36 kg per side per ream for 13/6 kg Need glassine.

Of particular importance in terms of commercial use of the new coating mixture for the packaging of foodstuffs and the like, the fact that the composition in addition to their particularly good water vapor insulation and heat seal characteristics, they are free of undesirable effects Is smell and does not stick together.

0098 13/1786

Claims (1)

A 33 863 m 0-123 March 25, 1969 Claims 1. Coating compound for packaging materials and the like, characterized by a content of a cyclized rubber as a film-forming base component, a waxy Water-damping insulation material as the first modifier and a heat sealable material as the second modifying agent. 2. Coating composition according to claim 1, characterized in that the content of cyclized rubber is between approx. 9 and approx. 80 % lies. 3. Coating composition according to claim 1 or 2, characterized in that the content of the waxy material is between 0 and approx. 70 % . 4. Coating composition according to claim 1, 2 or 3, characterized in that the content of heat-sealable material is between about 3 and about 65 % . 5. coating composition according to one of claims 1-4, characterized in that that the heat-sealable material consists of one or more of the following materials: a) vinyl acetate, b) vinyl butyral, c) vinyl acetate-ethylene copolymer, d) vinyl acetate-vinyl chloride copolymer, e) rosin resin glycerol ester, 0 0 9 8 13/1786 ^{BAD Or} * l®HAL i- subjects «• III * A 33 863 m ο - 123 March 25, 1969 f) polystyrene, g) polyisobutyl methacrylate, h) copolymers of acrylates and ethylenes, i) polyvinyl acetate with polyethylene, j) other vinyl polymers and copolymers, k) further aerosol polymers and copolymers, 1) further rosin esters, m) other types of resin derived from wood. 6. coating composition according to any one of the preceding claims, characterized characterized in that the waxy material consists of one or more of the following materials: a) paraffin, b) microwax c) vegetable wax. 7. coating composition according to one of the preceding claims, characterized characterized in that the cyclized rubber is a phenocyclized one Rubber is. 8. coating composition according to one of the preceding claims, characterized in that the film-forming base is a cyclized natural rubber, the first modifier a paraffin wax with a melting point of approx. 60 ° C. and the second modifying agent a vinyl acetate-ethylene copolymer is. 9. A coating composition according to claim 8, characterized in that _s the cyclized rubber, the wax and the copolymer in a ratio of about * »6: 25: 29 to each other. ^009813/1786 BADORiG ₁ NAL 15 6 9 3 3 863 m ο - 123 _ΛΛ 25th Mar r. 19 ^ 9 20 10. Coating composition according to one of claims 1 - 9, characterized in that that they are applied as a layer on the surface of a heat-sealable, water-vapor-insulating, flexible packaging material is upset. 11. coating composition according to claim 10, characterized in that that the V ^ -rpackungsmaterialunterlage from one of the following Materials consists of: a) glassine, b) bleached kraft paper, c) cellophane film, d) polyester film, e) polythene film, f) polypropylene film g) aluminum foil j h) cellulose acetate film, i) polycarbonate film, j) polystyrene film, k) nylon film, 1) sacran film, m) Poly te met luorathyler.fi In. 12. Coating composition according to claim 10 or 11, characterized in that that the packaging material is made of glassine exists and that this is on both sides with the coating mass in an amount of about 1.36 kg or less per side and per Ries, the Pdes to 279 πι, is coated. 8: 3/1786-8AD 5 6 9 3 Ί 7 863 m ο - 123 March 25, 1969 * ⁷ - -β * 13 · The method for producing de _r heißversiegeIbaren, water-vapor absorbing coating composition according to any one of claims 10-12, characterized in that at least one side of a packing material substrate with a 30 $ aqueous solution of the coating composition according to any one of claims 1 - 9 coated in a hydrocarbon solvent, and the solvent evaporates. BAD OFUGlNAL:. "D 981 3/1786