FR2541175A1 - PROCESS FOR FORMING A COMPOSITE CONTAINER AND CONTAINER THUS OBTAINED - Google Patents

Abstract

PROCESS FOR FORMING A COMPOSITE CONTAINER, WHICH INCLUDES A GLASS RING PART 12, THE SAID RING HAVING A TOP LIP 14 OF RING, CHARACTERIZED IN THAT IT CONSISTS OF: APPLYING A LAYER 16 OF THERMOS-SEALABLE ADHESIVE ON THE LIP OF THE RING 14, THIS ADHESIVE BEING A MIXTURE OF A SILANE AND AN ACRYLIC ETHYLENE ACID COPOLYMER, THE COPOLYMER HAVING A MELT FLOW INDEX OF AT LEAST 300; AND B.A DRY THIS LAYER OF THE THERMOS-SEALABLE ADHESIVE ON THE RING LIP. PACKAGING AND HOT PACKAGING OF VARIOUS FOODS, SUCH AS FRUIT JUICES, JAMS, TOMATO SAUCES, ETC.

Description

_ _ 2541175

  Process for forming a composite container and container obtained

  The present invention relates to a method of

  Hermetic seal in the form of a non-perforated lid of the thin and flexible type which is applied to the lip of

  the ring of a glass container, usually a recipe

  a large opening such as a jar Normally, the

  processes of this kind involve the use of

  non-perforated, thin and flexible key, usually made of aluminum foil, the underside of which is coated

  of a heat-sealable thermoplastic material, such a cover

  solidly engaging the upper lip of the ring of a glass container In current practice, the upper lip of the ring of the glass container is coated with a heat-sealable adhesive composition capable of interfacing the thin non-perforated lid and flexible coated thermoplastic and glass surface

of the container.

  Different ways of tackling the iron problem

  sealing a container containing a dry food or a cold-loaded food product, for example, dehydrated soups, refrigerated dairy products, etc. have been tried for example, the patent application

  British Patent 2,030,103 A, discloses a metal foil

  plicated on the opening and the edge of a glass container, attached to the edge by a heat-activatable adhesive, when applying heat and pressure to establish a connection between the glass container and the metal sheet without diffusion or deterioration of the adhesive bond when the container contains a foodstuff containing water, a binding promoting agent, such as an organic silicon compound, for example a silane

  having an affinity for glass, being applied to the

  hard container or incorporated into the adhesive It seems

  that this process does not concern the applications of

wise to hot.

-2-

  Japanese Patent No. 5,077,447 to a patent application

  container with an easy-open lid, describes a

  container obtained by covering a film or sheet of

  made of a laminate comprising a plastic sheet or foil and a plastic sheet, for example

  a plastic material bonded to hot plastic material

  heat-bonded and laminated on the metal foil is selected from modified olefinic resins, such as an acid-modified polyolefin, an ionomer, a

  ethylene / vinyl acetate copolymer, a copolymer of

  ethylenically unsaturated carboxylic acid or its ester, or a mixture of any enumerated material, or

  In addition, a more

  tite that the diameter of the part with a line of

  weakening to be opened in use on the inner portion of the lid -for easy opening in such a way,

  the small diameter opening of the film or foil

  superimposed on the part equipped with a business line

  easy opening lid by turning its

  hot-link plastic film side to the open-top cover

  Easy-to-cover part is connected by heating to a portion outside of the line

  weakening to be opened.

  The German patent application P 28 48 568 9 describes a method of hermetically sealing the glass containers to

  using metal sheets coated with a synthetic material

  The process consists of coating the border of the

  glass container with an adhesive in order to fix more

  metal foil coated with synthetic material

  glass container The adhesive is a pure solution

  organic or aqueous solution of an alkyl-trialkoxysilane, a

  alkyl-trichlorosilane, the alkyl radical of which bears a sub-

  c + n aç r yçe di epo vinyl, acrylo or

  methacrylo or an organic solution of an acid ester

  tanic monomer or polymer The coating is applied,

  dry it and then seal the waterproofing foil

-3 -

  by a known technique of pressing

  be the upper lip of the glass container using a heat-sealing head For the alkyl-trialkoxysilane,

  alkyl-trichlorosilane or a mixture of alkyl-alkoxychlo-

  rosinanes, mention is made of ketones, and especially acetone, as preferred organic solvents. However, for the titanic acid esters, a solvent based on

  benzene Each solvent requires the use of an organic compound

volatile.

  British Patent 1,538,642 discloses a recipe

  hermetically sealed container comprising a glass jar having an opening having an upwardly facing surface, a metal foil membrane extending over

  the opening of the container and thermally sealed to that

  ci and a click cap made of deformable plastic material

  by pressure and heat on the opening and the membrane

  sheet, the opening of the container comprising a bunker

  raised on its surface facing upward and

  continually extending around the opening, the capu-

  chon having a thickness on the surface facing the

  at least twice the height of the bead, the

  bead and the sheet element being embossed into the

  snap-cap plastic cap The membrane made of

  the metal may comprise an ethylene copolymer resin

  lene / acrylic acid having an activation temperature of 163 C as an undercoat for intimate contact

  between the sheet membrane and the bead of the container.

  German Patent DE 3,011,761 Ai entitled "Method for

  the joining of Substrates by Heat Sealing "based on the back-

  No. 3,011,761,443, discloses a method of joining

  sealed glass to glass or glass to metal in order to

  packaging that may contain dehydrated soups, yogurts or other

  The container and lid are fixed together

  of a heat-sealable adhesive that has been prepared by

  drolysis and polycondensation of: 4 - a) at least one organosiloxane of general formula (I): R Si X 4 m (I) wherein R denotes an alkyl, alkenyl, aryl, alkylaryl or arylalkyl radical; X denotes a hydrogen atom S or halogen or a hydroxyl, alkoxy, acyloxy or 11 radical; -NR 12 (R = hydrogen and / or alkyl radical) and m = 1,2 or 3, and at least one of the following compounds (b) (c) and / or (d); b) one or more silanes with a silicon function of general formula (II): Si X 4 (II)

  where X is as defined above but the

  not all are hydrogen;

  (c) one or more oxides which are difficult to volatilize,

  in the reaction medium or one or more compounds of an element from main groups Ia to Va or

  secondary groups I Vb or Vb of the Periodic Classification

  of the Elements, forming such an oxide with difficulty

  latilisable; d) one or more organic-functional silanes having the general formula (III): Rn (R "Y) psix (4-n-p) (III)

  in which R and X have the same meaning as above

  addition; R "represents a straight or branched chain alkylene radical which may be interrupted by oxygen or sulfur atoms or by NH groups, a phenylene, alkylphenylene or alkylenephenylene radical; Y denotes an atom

  halogen or, in a given case, a substituted amino group

  killed or, in any given case, a substituted anilino group,

  dehyde, keto, carboxyl, hydroxyl, mercapto, cyano, hydro-

  xyphenyl, carboxylic acid, alkyl ester, sulfuric acid,

  fonic, phosphoric acid, acryloxy, methacryloxy, gly-

  cidyloxy, epoxide or vinyl, N is 0, 1 or 2, and p

  is equal to 1, 2 or 3, the sum N + p = 1, 2 or 3; in pre-

  the amount of stoichiometrically required water -5-

  for hydrolysis and, in a given case of condensation,

  of a catalyst and / or a solvent, while in

  the case of the starting components (a) and (b), we can also

  use the oligomers of these silanes which are

  luble in the reaction medium. A number of problems have arisen in

  the techniques described above concerning the fulfillment

  For example, when performing the above-described manner hot-filling of acidic food products such as orange juice, or hot filling of non-acidic foods such jams, tomato sauces, ketchups and the like, in glass containers using

  the adhesive described above and thin metal lids

  plastic coated, also as explained above, there are various problems

  critical problem is the premature release of

  heat-sealing adhesive on the lip of the glass container ring immediately after filling, sealing and transferring the packaging to a cooling station.

  the container is heated by its hot-introduced contents.

  Similarly, while the sealing head by heat and

  the pressure tightly applies the lid to the

  container, this head brings a significant amount of additional heat to the packaging This combined heat supply causes the evaporation of some of the water to

  inside the packaging This vapor pressure provokes

  This force and the swelling of the lid cause the premature release of the lid in an unacceptable percentage of cases. The last stages of such a cooling process occur when the heat admitted is finally lost. a partial vacuum is established inside

  of the container and the lid sinks inwards.

  This vacuum causes increased stress on the seal between -6-

  the foil lid, the thermoset adhesive

  lable applied to the lip of the ring and the lip of the ring of the glass container There are many breaks

  seal when using, for

  Hot crimping, adhesives, and processes that are ideal for cold fill applications. Such seal failures cause leakage in the package and its contents are contaminated.

therefore unsellable.

  On the other hand, after long-term storage,

  from a few months to a year, packaging

  leakage as a result of the long-term storage instability of the adhesives used when they come into contact with very moist foods, so that

  atmospheric contamination enters the packaging

  holding the food and the product becomes once again

  salable This lack of durability in long-term storage

  packaging is particularly critical in

  of hot-loaded foods that normally

  can stay on the shelves of the store for a long time

  on the other hand, hot-filled food packaging

  there is a partial vacuum inside the container which increases the mechanical stress on the connection between the thin flexible metal lid, the heat-sealable adhesive and the lip of the container ring

glass.

  Also, many adhesives described above

  do not have more resistance characteristics

  long-term products, especially when put in contact with very acidic, very wet food products, such as fruit juices and tomato-based foods Thus, heat-sealable adhesives themselves lose their ability to close In addition, many commonly used methods require multiple layer coatings of different solutions, for example adhesives, crosslinking agents, and the like. liaison officers, etc. on the

  container ring lip This requires additional stages

  additional processing and a significantly higher initial investment for the purchase of the machines and also a large number of different solutions

  require time to mix, are frequently

  storing tables and most often contain

  In many cases, these solvents

  are not accepted for contact with food

  on the other hand, the solvent-based adhesive compounds

  to create special protection for the staff and.

  means for the control of the environment, the team

  and special techniques that militate against their use in many cases It is obvious that employment

  environmental pollution control equipment

  There is therefore a need in this industry for an additional process and compositions of heat-sealable adhesives.

  allowing the hot filling of foodstuffs,

  simple, reliable, free from organic vapors and

  to obtain after cooling a stable packaging

  and stable for a long period of storage.

vation.

  The object of the present invention is to provide a

  hermetically sealed container and method of manufacture

  of it, suitable for containing food products

  charged or hot-packed, this receptacle

  sedating an increased resistance to the appearance of leaks after

  filled with a hot food product, after the application

  lid and cooling at room temperature.

ambient temperature.

  Another subject of the invention is a closed container

  and its method of manufacture, suitable for containing hot-packaged food products, which container has better resistance to stress during long-term storage without causing leakage between the heat-sealable adhesive layer and the container.

  glass or its thin flexible lid.

  To realize the advantages of the invention which have

  have been indicated and also some others, we use a

  hermetically sealed closure of a glass container,

  container which has an upper part of a ring

  ending with a border portion or lip of a ring, the

  to heat at least the lip portion of

  glass vessel at a high temperature for a sufficient time and at a temperature sufficient to

  to oxidize any organic matter forming a

  duit on the lip of the ring Subsequently, apply

  at least one layer of heat-sealable adhesive on the

  top of the ring, said heat-sealable adhesive to be subsequently bonded between a thin, flexible metal cover having been coated

  of a thermoplastic organic material and the upper lip

  the glass container ring

  sealable, according to the present invention, is a mixture

  of a silane and an ethylene / acrylic acid copolymer.

  same, said copolymer having a flow index at

  the molten state of about 300 or lower After the application

  cation of the heat-sealable adhesive, the adhesive is dried and

  a thin, non-perforated lid is pressed which is a

  metal / plastic container against the glass container and

  hermetically seal with heat and pressure.

  using conventional means of heat sealing

under pressure.

  The container formed according to the present invention

  comes especially to receive food products

  hot-rolled and shows resistance

  high level of leakage during filling

  the hermetic seal and the cooling process

  and, on the other hand, is remarkably resilient

  99 _ tance to the appearance of leaks during long storage

term or handling.

  Other goals, features and benefits of

  the invention will emerge from the detailed description which

  will follow with reference to the accompanying drawings, in which: FIG. 1 is an exploded view of a lid

  flexible in a laminate of a non-per-

  drilled and a thermoplastic film and also showing

  the upper ring lip, coated with the heat-sealable adhesive, of a glass container; Fig. 2 is a schematic view of the process of the present invention for preparing, filling and sealing the package according to the present invention; and Fig. 3 is a schematic view of the method for cooling hot filled containers having the improved heat sealable adhesive which is the subject of

the present invention.

  The preferred embodiment of the present invention

  The invention is illustrated by way of example in FIGS. 1 to 3. FIG. 1 shows a partially cut glass container with the reference numeral 10.

  glass container 10 terminates in an upper ring

  12 which defines an opening in the container 10.

  In its highest part, the ring portion 12 ends with a lip portion 14 of the ring.

  lip 14 of the ring is a flat or slightly

  rounded as is common with glass containers to

  wide opening A thin layer of a thermoset adhesive

  lable 16 is placed on the lip portion 14 of the container ring 10 A membrane-type flexible non-perforated thin cover 18 having a geometry complementary to that of the ring portion 12 of the container 10 is mounted above

  of the container and can be attached to the ring part 12 of the

  10 by contact between the cover 18 and the lip portion 14 of the ring Normally, the cover 18 comprises

  a metal sheet portion 20 and a pelvic portion 22

  Thermoseal thermoplastic heat seal Part 22 in heat-sealable film may itself be a laminate

  assembled by stratification as will be seen later.

  In the preferred embodiment of the invention

  In one embodiment, the heat-sealable adhesive 16 comprises a mixture of a silane compound and an ethylene / acid copolymer.

  acrylic containing 80% ethylene and 20% acrylic acid.

  by weight in the copolymer structure and having

  a melt flow index of less than 300.

  The melt flow index particularly

  is about 75

  an ethylene / acrylic acid copolymer having a melt flow index of 75 to 300 provides a

  excellent heat-sealable adhesive with high resistance

  hot-melt glue which can be used in the processing of hot-packaged food without the use of solvents

organic in the adhesive.

  In this specification, the melt flow index is defined as the amount (in grams) of a thermoplastic resin that can be forced through a 2.1 mm orifice when subjected to strength of

2160 g, in 10 minutes, at 190 C.

  A preferred silane compound is the organofunctional "Silane A 1120" (Trade Mark of Union Carbide), which is a N- (e-aminoethyl) -amino-propyltrimethoxysilane, which is a functional silane. diamino This favorite silane

  is soluble in water which makes it particularly suitable

  suitable for applications in hot-fill food packaging, with the impossibility of using

  organic solvents in the composition of the heat adhesive

  moscellable All components of the adhesive must be such as to allow their contact with food

  FDA regulations and most organic solvents

  are not accepted The preferred silane is a liquid

  of straw color having a density of 1.03 to 25 C, a

  refractive index of 1.448 (n D 25 C) and a flash point of 11 -

138 C.

  The preferred ethylene / acrylic acid copolymer.

  has a melt flow index of about

  300 or lower and is able to train at ambient temperature

  water-based dispersions free of organic solvents Such a resin is abundantly available

  at Dow Chemical Company as Product No. PE 483.

  An even more advantageous resin is an ethylene copolymer

  lene / acrylic acid having a flow index in the state

melted about 75.

The metal foil 20 of the lid 18 is made of aluminum metal having a thickness of 38 to 63 microns. The thermoplastic and heat-sealable film 22 laminated on the metal foil 20 may be a "Surlyn" material.

  (registered trademark) provided by E I du Pont de Nemours & Com-

  pany) namely an ethylene / acrylic acid copolymer having any desired melt flow index or

  a laminate structure comprising a nitrocel-

  lulose in contact with the aluminum film and

  even coated with a polyvinyl butyral polymer for

  aluminum / nitrocellulose / polyvinylbuty-

  A preferred material is "Surlyn" grade No. 1652 which is an ionomeric resin having zinc counter-ions with a melt flow index of 5.0. The three lids 18 described above are all suitable for use with advanced heat seal adhesive

  According to the invention, each lid can form excel-

  slow, hot-filled packaging with the new adhesive described, showing short-term stability

  cooling since the high temperature of the

  wise to warm up to room temperature and also excellent long-term durability without showing up

  a significant proportion of leaks in the containers.

  The method according to the present invention for

  parry and fill containers 10 is more clearly

  shown in Figure 2 A 24 Distribution Station 12-

  treated containers provides a continuous distribution of

  Glass containers 10 for use in the process of the present invention The containers 10 provided by the station 24 are processed according to conventional glass container manufacturing techniques, i.e. the surface has been treated on the outside the container 10 by

  combinations of thin transparent coatings Frequency-

  such containers are treated with tetrachloro-

  This is known as a "hot end coating" while the containers 10 have a considerable heat of manufacture. The containers 10

  are still coated with layers of polyethylene,

  or other organic lubricant that is applied

  in the form of what are known as "terminating

  According to the present invention, it has been discovered that

  containers must be advantageously treated, in order to

  firing at optimal results, in order to remove or

  oxidation of cold end-processing materials such as oleic acid, before application of the

  heat sealable adhesive layer 16.

  The stage of flame treatment 26 ends the

  total or partial oxidative removal of the lubricating materials of the cold end treatments by subjecting at least the lip portion 14 of the ring of the container 10 to a flame at

  high oxygen content to oxidize the materials of the

  cold endings Normally, the temperature is raised

  erase the lip portion 14 of the ring at about 1490 C for a few seconds to effectively eliminate a

  significant amount of the material of the terminating

  According to the present invention, it has also been determined that the long-term storage stability and leakage resistance of the package is improved by subjecting the lip portion 14 of the multi-flame ring in series. For example, the lip portion 14 of the ring or so-called opening of the container 10 passes under a linear 13-series of ramp-type gas burners producing a flame of oxygen-rich gas to oxidize or burn the gases. In the preferred embodiment of the invention, three ramp-type gas burners directed against the lip portion 14 of the ring remove sufficient organic material from the aforementioned cold end treatment on the lip portion 14 of the ring. cold end-processing to facilitate the possibility of

  the heat-sealable adhesive layer 16 during filling

  subsequent wise, cooling and long-term storage. After the stage of treatment with the flame, the containers 10 are advantageously placed in a stage of

  cooling 28 o the lip portion 14 of the ring is

  has been cold since about 3000 C to a temperature of

  This lower temperature facilitates the application of the heat-sealable adhesive described but does not significantly delay the treatment of the containers 10 as would be necessary if the containers 10 were to be heated.

  return to room temperature.

  After the cooling stage 28, the reci-

  10 are transferred to an application stage of

  the adhesive o a layer of heat-sealable adhesive is

  plicated on the lip portion 14 of the ring to form a thin film having about 50 microns thick On

  can use all the standard techniques of application

  tion; however, a roll-over air coating device

  Suitable for continuous application of adhesive on a linear row of containers is preferred.

  such a roller air coating device normally comprises

  wrongly a cylindrical rubber roller or a

  elastic material, which is drawn downwards by a res-

  to come into forced contact with the portion 14 of the container ring during its passage under the roller

  rollers are normally mounted transversely to the di-

  recency of the progression of the containers and are studied 14 - to apply about 0.025 mg / m 2 M equivalent of dried coating by contact with the lip portion 14 of the ring Can be used coating weights as low as 0.0075

  mg / mm 2 but such a low load does not always compensate

  days surface irregularities in the geometry of the lip of the ring Weights greater than 0.015 mg / mm 2 are preferred A practical upper limit is about

0.08 mg / mm 2.

  After the adhesive application stage, the containers are transferred to a drying stage 32 o.

  forced drying of the heat-sealing adhesive layer

  In the preferred embodiment of the invention, a row of quartz IR heaters providing radiant energy of 1.15 micron is used to the containers 10 to raise them in a very short time, for example. example of 6 seconds at about 720 C Such a temperature thermally dehydrates the adhesive compound and forces it to form a stubborn seal with the lip portion 14

of the ring.

  After the initial coating and the stages of

  the resulting article is a glass container

  both a heat sealable adhesive coating dried on the

  lip of the ring Such an article is a container made

  site that is stable in storage and can be shipped as a separate commercial item to a filling shop

  or it can be filled immediately.

  For many applications, when

  use food products that are very difficult to

  it is preferred that the dried and coated containers, on leaving the drying stage 32, be recycled by

  a return loop 33 at the application station 30 of the adhesive

  for a second application of adhesive which, when dried,

  is equivalent to one layer of 0.025 mg / mm 2, followed by a new

  passing through the drying stage 32 to perform a se-

  drying process during which the second layer of adhesive is dried to come into tough and sealed contact with the first layer of adhesive;

  many applications it is not necessary to

  kill a double coating of the lip part 14 of the

  if the lip is very flat, when the ring lips are a little irregular, as is common with

  containers for normal use, a second application of adhesion

  it is necessary to achieve the best result

  the excellent durability of the hermetic closure

  that during cooling and also the best conditions

  long-term storage of the container with this

  double layer, containers are obtained that can contain

  high-moisture and high-moisture foods, such as fruit juices, during

  cooling and during long-term storage

with a minimum of leaks.

  After the containers leave the drying stage 32, they are transferred to a hot filling and lid-filling stage 34, as seen in FIG. 3. At stage 34, a hot food product at a temperature of 30.degree. approximately 770 to 100 C is placed in the container 10 After filling the container 10 with the hot food product, the lid 18 is applied to the lip portion 14 of the ring and hermetically united

  with the latter with the help of a classic head of sou-

  Such a head applies the heat and pressure

  down on the cover 18 to force the pel-

  thermoplastic heat sealable hose 22 of lid 18

  to come in tenacious grip with the adhesive layer thermoscel-

  lable 16 which is in intimate contact with the lip portion 14 of the ring After the containers have been filled and

  hermetically sealed, they are transferred to a

  multiphase cooling 36 where they are cooled from the filling temperature 77 to 1000 C to the

ambient temperature.

  The hot-filled containers are treated in the multi-stage filling stage 36 to result in a hot-filled container dispensing stage 38.

  which places the containers in a linear row for trans-

  at a stage 40 of primary treatment with hot water.

  Receptacles coming from the distribution 38 of the

  Hot-filled containers contain a product that is normally at a temperature of 77- to 1000 C. Stage 40 primary steam treatment hot water submits these

  containers with hot water vapor at a temperature of

  600 to 820 C for 1 to 10 minutes, normally

  The containers are transferred from the primary treatment to hot water at a stage 42 of secondary treatment with hot water in which they are sprayed for about 3 minutes at a water temperature of 820 C.

  hot water at a temperature of 270 to 490 C during

  1 to about 10 minutes, normally for 3 minutes

  at a water spray temperature of about 27 ° C.

  Receptacles at 490 C are transferred from stage 42 of processing

  secondary to hot water at a stage 44 of treatment.

  with cold water or closed hermetically sealed

  are immersed in a cold water bath or receive a spray of cold water at a temperature of

250 C for 20 to 30 minutes.

  It has been found that when hot fillings are essential for foods such as orange juice, ketchup, mustard, puree and sauces

  tomatoes, jellies, condiments and food products

  similar requirements requiring hot filling, the

  according to the present invention, using the thermal adhesive

  described sealant, makes it possible to obtain hermetically sealed

  closed which offer excellent resistance to

  during the cooling stage 3 6 with multiple phases

  which can be seen in detail in sub-stages 38 to 44,

  as well as an excellent resistance to the appearance of

  during long-term storage, from a few months

than a year.

  As previously described, the thermoset adhesive

Z 541175

  According to the present invention, a silane compound mixed with an ethylene / acrylic acid copolymer having a melt flow index of less than 300, an ethylene content of 80% and an acrylic acid content of 20%. Such an ideal ethylene / acrylic acid copolymer is sold by Dow Chemicals USA under the trademark "PE 483" having the properties

  following physical characteristics when purchased in the form of a

  Persion: Solid content (%) Brookfield Viscosity, 50 rpm 100-200 p H 9-10 Surface tension, dynes / cm 46-49 Weight per liter (kg) 1 Specific gravity, liquid, g / cm 3 at 25 ° C 0.985 Specific gravity, g / cm 3 at 25 ° C 0.960 Ammonia water vehicle Volatile organic compounds None Acid number (Dow) 156 Melt flow rate (ASTM D-1238) 300 g / 10 min Melting point (Dow, DSC) 85 C Vicat softening point

(ASTM D-1525) 50 C

  Tensile strength (ASTM D-638) 112 da N / cm 2 (for compression molded samples) Elastic limit (ASTM D-638) 63 da N / cm 2 (for compression molded samples) Elongation% (ASTM D- 63 8) 3 00

  Normally, the silane component of the heat adhesive

  moscellable constitutes from 4 to 12% by weight of the total

film of dried adhesive.

  The adhesive containing the non-organic solvent according to the present invention normally comprises about 25 g of the copolymer dispersed in 100 g of water with about 2 g of silane incorporated.

  no solvent is prepared as in the following example.

  The aqueous dispersion containing the copolymer, preferably

  the "Dow 483" product referred to, is

  in a mixing container and is stirred at a rapid rate

  is just enough to form a whirlwind A

  minimal tourbillon is desirable because the action of a tour-

  violent billon causes the imprisonment of far too much

  of air in the dispersion, which is unfortunate

  a slight swirl in the dispersion water

  of the copolymer, 3 parts by volume of a solution of

  at 58% by volume of ammonium hydroxide per 100 parts

  by volume of the copolymer dispersion First of all,

  ammonium hydroxide is poured slowly into the swirl

  lon to facilitate the proper mixing of the amide hydroxide

  in the dispersion of the copolymer in order to contribute to the formation of a stable emulsion Then, 2 parts by volume of the silane, preferably Union-Carbide "A 1120" silane, are slowly added, per 100 parts by volume of The dispersion of the copolymer by pouring the silane into the vortex of the mixture The mixture is stirred slowly with a minimum of swirling for 2 to 3 minutes.

  to form a stable dispersion containing a non-solvent

  organic, which can then be applied to the lip portion of the glass container ring to form a layer

  heat-sealable adhesive 16 according to the present invention.

  For high speed coating lines, the mixture

  adhesive described above foam sometimes during the application

  In such a case, after the addition of the silane, an additional 4 parts by volume of ammonium hydroxide is incorporated by stirring.

  at 1% and the resulting adhesive is stirred for 2 to 3 minutes.

  To dismantle the excellent durability of a packaging

  According to the invention, the following tests are carried out: on 11 wide-opening glass containers, an adhesive coating having the following composition is applied twice, by volume: 100 parts of copolymer 19-483 from Dow Chemical USA ; 3 parts of ammonium hydroxide

  at 58% (said concentrate); 2 parts silane A 1120 from Union-

  Carbide and 4 parts of a 1% solution of ammonium hydroxide

  Monium in deionized water, all ingredients being added in the order indicated and under the conditions described above. The 11 containers are coated with the adhesive mixture. The coated containers are heated at 60 ° C. for

  minutes after the first stage 30 application of -

  the adhesive After the second application of the adhesive with

  passing through the return loop 33, heat the reci-

at 5 o C for 45 minutes.

  The coated containers are immersed in a water bath at 60 ° C. to simulate the preheating apparatus of containers in an industrial hot-filling line. The containers are then filled to the brim with orange juice at 100 ° C. Pre-formed 50 micron aluminum lids with "Surlyn" underlay

  placed on the containers and hot-tempered with the help of

  of a conventional hot pressurized welding head.

  The working conditions of the welding head are temperature of the elastic surface of the joint 197-2080 C Welding pressure 6 bar Pressing pressure on the edge of the lip 3.5 bar

Weld duration 1 second.

  After sealing, the containers are cooled

  pients for 3 minutes in a steam chamber at 820 C. Then the containers are cooled for 3 minutes

  in a spray of water at 490 C Finally, we cool

  says the containers for 3 minutes in a stream of water

  at 230 C No leaks are detected.

  After cooling to 23 ° C, the recipes are

  hermetically sealed in an exsiccator under

  A vacuum equal to 234 millibars is applied to the exsicca-

-20 -

  and hold it for 1 minute.

  following the vacuum at 878 millibars for 5 seconds

detects no leakage.

  This test demonstrates the durability to cooling and durability under a high vacuum applied to the packaging

according to the invention.

  A second test is carried out to demonstrate the durability of a package according to the present invention when subjected to heat-filling to primary and secondary heat treatment and cold water treatment to simulate approximately one operation.

  industrial food packaging.

  A heat-sealing adhesive dispersion is prepared

  ble as follows: 3500 ml of an ethylene / PE-483 acrylic acid copolymer were stirred to form a vortex

  as described above and then we add

  to this whirlwind of the copolymer dispersion, 105

  ml of a 58% by volume solution of ammonium hydroxide.

  70 ml of silica are added to the vortex by stirring.

  Organo-functional lane type A 1120 (Union-Carbide)

  280 ml of a solution of 1 part by volume of ammonium hydroxide and 100 parts by volume of distilled water are subsequently added to the solution, in order to reduce the foaming during the application by the roller system of the type described

above.

  Twice 13 containers are covered with large

  with the same roller coating device using the adhesive dispersion to establish a layer of about 0.05 mg / mm 2 of dried adhesive The first layer of heat-sealable adhesive is dried for 15 minutes at 60.degree. 'C.

  and the second layer for 45 minutes at 93 ° C, and

  chills the containers at room temperature after each

adhesive drying cycle.

  Before filling with a hot-packaged product, each container is immersed in a water bath at 60 ° C. to simulate a device for heating the bottles in an industrial filling line. Then, the containers are filled up to the overflow. with jelly

  strawberries at 770 ° C. Then place on the opening of the container.

  a type aluminum foil lid of the type described with an undercoat of "Surlyn" quality ionomer resin type 1652 is sealed. The lid is heat-sealed using a conventional hot and press-welded head.

  under the same conditions as in the previous example.

  After closing, the containers are first cooled in a first stage of treatment with hot water at 820 C for 3 minutes. The containers are then transferred to

  secondary treatment stage 42 with hot water where they

  water spray at 490 C for 3 minutes.

  The containers are moved to the stage 44 of treatment in cold water or subjected to a current of cold water at 260 ° C.

  for 3 minutes Finally, we cool all the reci-

  at room temperature in the ambient air.

  After cooling to room temperature,

  hermetically sealed containers are placed in an exsic-

  Vacuum tester for tests During the test, any rupture of the seal becomes evident by the escape of the air bubbles from the package. Each container is placed in a vacuum desiccator filled with water and exposed. at a vacuum equal to 234 millibars applied and maintained for 1 minute After this minute, we increase the vacuum to 878 millibars and we maintain this

empty for 5 seconds.

  As a result of this test, 12 of the 13

  live as well under a low vacuum as under high vacuum under the conditions of the test; the only container that does not support the test is broken due to cracking

  in the glass wall of the container itself.

  Another attempt is made to determine the

  long-term storage of the packaging In this test, 14 containers are filled as described above with

  orange juice at 1000 C and seal

  22 - first test the containers under a vacuum of 234 millibars as described above for one minute and then under a vacuum of 878 millibars for 5 seconds There is no breakage is then stored hermetically closed containers for 22 days at 380 C in a room accelerated aging A day in the accelerated aging chamber at 380 C corresponds to little

  within 3 days under normal conditions of use.

  After long-term storage, all the containers are again subjected to vacuum desiccation of 234 millibars for 1 minute.

  containers after the long storage period described.

Claims (4)

  A method of forming a composite container, which comprises a glass ring portion (12), said ring having an upper ring lip (14), characterized in that it comprises: a coating (16) of heat-sealable adhesive on said ring lip (14), said adhesive being a mixture of a silane and an ethylene / acrylic acid copolymer, said copolymer having a melt flow index of 300 or less ; and b to dry this layer of said heat-sealable adhesive on the lip of the ring.   Process according to claim 1, characterized in that said heat-sealable adhesive layer is 0.0075 to 0.08 mg /   mm 2 of the contact surface of the ring lip.   3 Process according to claim 1, characterized in that   said silane is a diamino-functional silane.   4 Process according to claim 3, characterized in that   said diamino-functional silane is N- (P-aminoethyl) -y-   amino-propyl-trimethoxysilane. Process according to claim 1, characterized in that said copolymer has a melt flow index from about 75 to 300.   Process according to claim 1, characterized in that said copolymer contains in its structure 80% of ethylene and 20% acrylic acid.   Method according to claim 1, characterized in that   drying said adhesive by exposure to infrared rays.   The method of claim 1, further comprising applying a second layer of said adhesive to said ring lip and drying said second layer. Composite container, characterized in that it comprises: a hollow unitary container (10) having a ring portion   upper ring (12), this ring having a lip   ring gear (14); and a layer (16) of heat-sealable adhesive on said ring lip, said adhesive comprising a mixture of a silane and an ethylene / acrylic acid copolymer, said copolymer having   a melt flow index of 300 or less. 24 2541175   Container according to claim 9, characterized in that said adhesive layer is 0.0075 to 0.08 mg / mm 2 of the   contact surface of the ring lip.   Container according to claim 9, characterized in that said silane is a diamino-functional silane. Container according to claim 11, characterized in that   that said diamino-functional silane is N- (P-aminoethyl) -y-   amino-propyl-trimethoxysilane. Container according to claim 9, characterized in that said copolymer has a flow index in the state melted from about 75 to 300.