FR2460780A1 - METALLIZED PAPER COMPRISING A BONDING FILMOGEN RESIN AND PROCESS FOR PREPARING THE SAME - Google Patents

Abstract

THE INVENTION CONCERNS METALLIC PAPER AND ITS MANUFACTURING PROCESS. IT RELATES TO A METALLIC PAPER INCLUDING A PAPER SUBSTRATE HAVING A THIN CONTINUOUS COATING OF A FILM-GENERATING RESIN ON AT LEAST ONE SIDE, AND A METAL FILM VACUUM DEPOSITED ON THE RESIN COATING. A THIN COATING OF POLYVINYL ALCOHOL IS ADVANTAGEALLY SHAPED ON THE OTHER SIDE OF THE PAPER. THE RESIN APPLIED IS A FILM-GENERATING RESIN WITH ADVANTAGEOUSLY A POLAR GROUP AND IT IS FOR EXAMPLE OF AN OLEFINIC RESIN WITH CARBOXYL GROUPS OR OF AN IONOMIC RESIN. APPLICATION TO THE MANUFACTURE OF METALLIC PAPER HAVING THE PROPERTIES OF PAPER BUT THE SHINE OF METAL.

Description

The present invention relates to a paper

  and its method of preparation. More precisely,

  it concerns a metallised paper, in particular with aluminum

  minium, practically retaining the properties of paper and low permeability to air and moisture and

  wherein a smooth metallized layer having an excellent

  slow metallic luster is firmly bonded to the paper substrate; it also relates to a manufacturing process

of such a paper.

  The metallized paper used is very much

  held by gluing an aluminum foil onto paper

  because of its decorative appearance and low permeability

  air and moisture, for objects which

  be protected against the absorption of moisture or the release of volatile constituents, for example as

  packaging of confectionery, tobacco,

  drugs, etc. and as labels. We use a machine

  composite material formed by gluing a sheet of

  zinc on paper in paper capacitors.

  However, such a paper comprising a

  metal has the disadvantage of a high cost of

  because the thickness of the metal foil can only be reduced to a certain limit and

  the leaf may have stings; in addition,

  sheet metal are preponderant and

  partially remove the characteristics of the

  pier. To overcome this drawback, vacuum deposition of aluminum or zinc can be used on one side of the paper or both. A product formed by vacuum deposition of such a metal on non-paper

  treaty still has essentially the properties of the

  pier itself and it has a high permeability to air and is not resistant to moisture; in addition, the irregular surface of the paper reproduces itself as it is on the metallized layer which is extremely

  thin. So, the product has no shine and the coating-

  paper is not of interest.

  A paper capacitor, as indicated previously, must have a smooth surface, an even thickness

  and a total absence of pitting, but the pre-treatment method

  zinc deposit city does not meet these criteria.

  Vacuum deposition of a metal such as aluminum

  minium or zinc, on a plastic film, and the bonding of this metallized film on the paper is also possible, following a known operation. For this purpose, the plastic film must be coherent and must have a high thickness. A sheet formed by

  gluing such a plastic film onto

  pier retains very little paper properties such as bursting and folding property, and presents

  especially the properties of the plastic film.

  As a result, the bonding of the paper to the metallic film

  Plastic material is of no interest.

  Similarly, it is also possible to glue a film of plastic material on paper and to deposit a

  metal on the surface of the plastic film of the pa-

  In this case, the thickness of the foil

  plastic material may be smaller than when

  the use of a coherent film. However, the thick

  the plastic film is still relatively

  important, and the properties of the paper tend to

  dance to disappear. In addition, this method is not cost effective because a roll of rolled paper, having a large diameter, must be installed in a device.

discontinuous deposition under vacuum.

  The invention relates to a metallized paper

  virtually preserving the properties of paper such

  that its bursting property, its aptitude for

  folding (flexibility), its mechanical resistance, its

  and its hardness, in which a metal layer

  smooth, with excellent metallic luster, is

  firmly glued to the paper substrate.

  The invention also relates to a metal

  which retains substantially the properties of paper and has a low permeability to air and moisture and in which a smooth metallized layer,

  having an excellent metallic luster, is firmly

to the paper substrate.

  The invention also relates to a metal

  in which the properties of the metal surface

  are not deteriorated even when the paper is stacked.

  It also relates to a method of manufacturing

such a metallized paper.

  More specifically, the invention relates to a metallized paper which comprises a paper substrate

  on one side at least one thin coating

  tinu a film-forming resin with good

  adhesion properties to the metal, and a metal film deposited on the surface of the resin coating formed on

the paper substrate.

  The essential characteristic of paper

  metallized according to the invention is that a coating

  tinu a film-forming resin with good

  adhesion properties on the metal, forms an intermediate layer that smooths the surface of a paper substrate and increases adhesion

  mutual support of the paper substrate and the metal

  the thickness of the resin being sufficiently

  weak so that the properties of the paper do not disappear

almost not feel.

  The term "film-forming resin having good properties of adhesion to metal" used in

  this memo also refers to thermosetting resins.

  plastics without a polar group such as a copolymer

  styrene and butadiene and polybutadiene. Resolutions

  synthetic thermoplastics having at least one polar group, such as a carboxyl group, a carboxylate group (i.e. a carboxyl group in the form of a salt or an ester), a halogen atom , an acyloxy group or a nitrile group, especially those containing a carboxyl group or a salt carboxylate group, exhibit excellent adhesion to the metal and are therefore advantageous.

  We consider in the following of the present

  particular examples of resins containing

Polar groups.

  (1) Olefinic resins modified by

carboxyl groups.

  This group of resins contains copoly-

  Olefins and unsaturated carboxylic acids

  ethylenic ration at e, 8, or their derivatives, and

  copolymers formed by grafting carboxylic acid

  with ethylenic unsaturation,

  their derivatives are olefinic polymers.

  Olefins are, for example, those

  contain 2 to 10 carbon atoms, such as ethyl

  lene, propylene, butene-1, methyl-4-pentene-1, and hexene-1. Examples of olefinic polymers are polyethylene, polypropylene, polybutene-1,

  polymethyl-4-pentene-1, the copolymers of ethyl-

  ethylene and propylene, copolymers of ethylene and

  butene-1, copolymers of ethylene and methyl-4-

  pentene-1, copolymers of ethylene and hexene-1, copolymers of propylene and butene-1 and

  copolymers of methyl-4-pentene-1 and decene-1.

  Examples of carboxylic acids with

  ethylene teat in a, 1, which can be copoly-

  merited with these olefins or by grafting onto poly-

  olefinic monomers are the ethylenically unsaturated monocarboxylic acids in a, f, having 3 to 10 atoms

  carbon, such as acrylic, methacrylic

  crotonic, isocrotonic and 1-undecylenic, and ethylenically unsaturated dicarboxylic acids having 3 to 4 carbon atoms such as

  maleic, itaconic, citraconic and 5-norboric acids

  nene-2,3-dicarboxylic acid. Examples of derivatives of these

  unsaturated carboxylic acids are the derivatives of

  carboxylic acids which can be converted into corresponding acids by reaction with water, such as acid anhydrides, esters, amides and imides.

  of. These carboxylic acids with ethylenic unsaturation

  that in a, r or their derivatives can be copolymerized in an amount generally between about and 45% by weight, and preferably between about 10 and 20% by weight in the copolymer, type graft or not. If applicable, the copolymer, graft type

  or not, obtained with the aid of carboxylic acid derivatives

  can be converted into a carboxyl group-containing copolymer by hydrolysis. At least some of the free carboxyl groups present in the copolymer, whether grafted or not, containing carboxyl groups may

  be in the form of salts, for example alkaline or alkali

  non-earthy (for example in the form of potassium, sodium, calcium or zinc salts) or may form a

  structure crosslinked by transcon-

dirty containing these metals.

  Examples of modified olefinic resins

  carboxyl groups are the copolymers of ethylenediamine

  ne and acrylic acid, ethylene copolymers,

  of methyl acrylate and acrylic acid, the copo-

  polymers of ethylene and methacrylic acid,

  ethylene, methyl methacrylate and

  of methacrylic acid, polyethylene grafted with

  acrylic, maleic anhydride grafted polyethylene and maleic anhydride grafted polypropylene. Among these resins, ionomer resins

  and polyolefins grafted with carboxylic acids

  with ethylenic unsaturation in a, R having an indi-

  this acid between about 30 and 150 and preferably

  between 50 and 130, are particularly

  advantageous. An example of an ionomeric resin is a

  cross-linked by transverse ionic bonds

  of Na + or K copolymer of ethylene and methacrylic acid

  with a content of methacrylic acid units

  from about 5 to 45% by weight and preferably from about 10 to 20% by weight. When the content of methacrylic acid units exceeds 45% by weight, a coated film prepared with the resin has poor resistance to water and heat. When

  this content is less than 5% by weight, the

  spontaneous persion of the resin becomes bad. About 30 to 80% of the methacrylic acid units present are neutralized with Na or K. The ionomer resin disperses spontaneously as indicated below.

  and forms an aqueous dispersion having a small

  particle size and good stability during storage.

  (2) Vinyl resins with halogen groups.

  This group of resins includes vinyl chloride resins such as polyvinyl chloride and ethylene vinyl chloride copolymer, vinylidene chloride resins such as polyvinylidene chloride, chloride copolymer, and the like.

  polyvinylidene, butadiene and methacrylate acrylate.

  thyle, and the copolymer of vinylidene chloride and acrylic acid, and chlorinated polyolefins such as

  chlorinated polyethylene and chlorinated polypropylene.

  These resins can be used alone or in combination

  mechanical binder Resins of vinyl chloride

  are particularly beneficial.

(3) Vinyl acetate resins.

  This group of resins includes polyvinyl acetate, copolymers of vinyl acetate and ethylene, vinyl acetate copolymers and

  acrylate esters, the acetate copolymers of

  nyl and dibutyl maleate, and the products

  formed by partial saponification of these polymers.

(4) Acrylic resins.

  These resins include homopolymers and copolymers of acrylic monomers such as acrylic acid, methacrylic acid or esters of acrylic or methacrylic acid with alkyl groups.

  C1 to C8 such as methyl acrylate, methacrylate

  methyl crylate, ethyl acrylate, butyl acrylate, octyl acrylate and isobutyl methacrylate, and copolymers of these acrylic monomers in predominant proportion with a small proportion of other comonomers such as styrene, acrylonitrile, vinyl chloride, vinylidene chloride and ethylene. Examples of copolymers of an acrylic monomer and other comonomers are copolymers of styrene, butyl acrylate and butyl methacrylate, copolymers of styrene, methyl methacrylate and butyl methacrylate,

  and copolymers of styrene and methacrylate

Thyle.

  (5) Other resins containing groups

lar.

  Copolymers of acrylonitrile and butadiene

  diene. The resins containing polar groups, including the preceding examples, may be used alone or in combination with the resin. Among the resins indicated, the olefinic resins modified with

  carboxyl groups are the most suitable.

  Resins containing polar groups

  may be used in admixture with resins

  patients with no polar groups. For example,

  olefinic resins modified with car-

  boxyl can be mixed with acetate resins

  tellE that a copolymer of ethylene and acetal

  vinyl, its saponification product or

  olefinic salts such as polyethylene, poly-

  propylene, polybutene-1, polymethyl-4-pentene-1,

  copolymers of ethylene and propylene, copolymers

  mothers of ethylene and butene-1, copolymers of

  ethylene, propylene and butadiene terpolymers, terpolymers of ethylene, propylene and dicyclopentadiene, terpolymers of ethylene, propylene and ethylidenenorbornene, copolymers of propylene and butene- 1, copolymers

  of propylene and butadiene and mixtures of these

  lymères. When the resin containing polar groups

  res is used in admixture with a resin which does not

  not hold polar groups such as resins

  above-mentioned olefins, the proportion of the resin de-

  polar groups should be limited to one

  which does not cause a net reduction of the

  the mixing of resins with the metal. Although the

  mixing portion is not essential, it is generally desirable for the polar group-free resin to be used in an amount of less than 50% by weight and preferably 40% by weight, by

  relative to the total weight of the two resins.

  The aforementioned resin used for forming

  of the intermediate layer has advantageously

  a melt index, measured according to ASTM standard

  D 1238-57T, of at least about 0.1 g / 10 min and preferably at least about 0.5 g / 10 min, so that

  forming a continuous coating is convenient.

  A paper formed by a natural paste is

  advantageous as a substrate for the application of the

  filmogenic sine aforementioned having good adhesion to the metal. However, papers of synthetic paste or containing such a paste, prepared by mixing a

  synthetic paste and a natural paste, may also

  if forming the substrate used according to the invention.

  The term "paper substrate" used

  in this specification refers not only to the

  pier formed from a natural pulp but also paper made of a synthetic paste and paper sheets prepared from a mixture of natural dough

and synthetic paste.

  Examples of natural pastes are mechanical pulp, chemical pulp (sulfite or sulphate, etc.), semi-chemical pulp, paper pulp, cotton pulp and hemp pulp. Examples of synthetic pulp are short fibers of between 0.5 and 20 mm in length, formed of a thermoplastic resin such as polyethylene,

  polypropylene, polystyrene, polyvinyl chloride

  vinyl, copolymers of styrene and acrylonitrile, polyamides and polyesters. The sheet of these paste materials can be provided by any method

  known. For example, the above-mentioned pasta can be

  persists, either alone or in a mixture in water, and

  the suspension can be sheet-fed by a technique

  than conventional training in the wet state. This wet type process is generally used for sheet setting. Alternatively, a nonwoven web may be prepared by a dry process from the aforementioned doughs. These two sheet forming processes can

to be used according to the invention.

  The paper containing a synthetic paste, used according to the invention, can be in the form of a sheet of a uniform mixture of synthetic paste and

  of natural dough, a superposition of

  mixes of synthetic paste and natural paste

  of different proportions, or of a different

  superposition of a core layer formed by a film

  natural pulp and a superficial layer

  Moved by a sheet of synthetic paste alone or a mixture of synthetic paste and natural paste. The surface of the paper containing a synthetic paste may be treated by a heating calender or a mineral filler such as a clay may be incorporated in this

  paper. Like synthetic pulp paper and paper

  pier containing a synthetic paste have a good

  water resistance, they do not wound up when they are

  coated with an aqueous dispersion of the film-forming

  gene, described hereinafter, and

  metallized papers prepared from these substrates

  strats are suitable as wrapping papers. In addition,

  since they can be molded and sealed

  the resulting metallized papers are suitable

  to the formation of food containers by stamping

deep sage.

  As long as the film-forming resin can re-

  to smooth out the irregular surface of the paper substrate by forming a continuous coating thereon, it should be applied as a layer as thin as possible so that the properties of the substrate of

  such as the bursting property, the ability to

  folding study (flexibility), mechanical strength, elongation and hardness can be practically preserved. The thickness of the continuous layer of resin

  varies with the nature of the film-forming resin used.

  The thickness of the resin coating which is suitable in general

  Neral to a paper substrate is between about 1 micron and preferably about 2 to 20 micron.

  Thus, the film-forming resin can be applied

  on the paper substrate by any known method which allows the formation of a very thin continuous coating. For example, depending on the nature of the resin used, the coating in the molten state or in solution can be used. In the case of the coating in the background state the formation of a thin, continuous and smooth layer is difficult. When coating in solution, the resin

  can be absorbed by paper so that

  The latter's properties tend to change. We build

  According to the invention, a very thin continuous layer

  resin can be formed very easily by re-

  clothing of the paper substrate with an aqueous dispersion

  of the film-forming resin, so that this process is

  most convenient for the implementation of the invention.

  The aqueous dispersion of the film-forming resin may be prepared in a known manner. For example, it may be prepared by forming an aqueous dispersion of the film-forming resin by emulsion or suspension polymerization, or by re-dispersing a separately prepared film-forming resin in an aqueous fluid. The concentration of the resin in the aqueous dispersion is not essential and may vary

  with the nature of the resin used, etc. The concentration

  The solids content of the aqueous dispersion, giving a viscosity suitable for the coating, is advantageously from about 10 to 60% by weight and preferably from about 20 to 50% by weight.

  weight, based on the weight of the aqueous dispersion.

  It is advantageous that the resin dispersed in the

  aqueous persion in the form of particles having the smallest particle size possible. It is

* desirable that the resin particles have a dia-

  average particle size of between about 0.005 and 20 microns and preferably between about 0.01 and 15 microns so that the viscosity of the aqueous dispersion, the regularity of the resulting coating, etc.

be good.

  When emulsifiers or surfactants

  active ingredients and other adjuvants used for

  Emulsion or suspension in the preparation of the aqueous dispersion are volatile, they can evaporate when the paper substrate, coated with the aqueous dispersion, is placed under vacuum for metallization. As a result, creating a high vacuum is difficult or it takes a lot of time

  to obtain such a vacuum. Thus, when using

  of these adjuvants, their quantity should be as small as possible and should be adjusted for example to a value of less than about 5% of the weight of the

  film-forming resin present in the aqueous dispersion.

  It is also recommended to use emulsifiers

  surfactants or surfactants of high molecular weight,

having low volatility.

  In this respect, the olefinic resin modified with carboxyl groups, in particular the resin

  ionomer and a polyolefin grafted with a carboxylic acid

  is a particularly advantageous resin in the context of the invention because it has a spontaneous dispersion, can be redispersed in the form of slurries

  particles in an aqueous fluid and has an ex-

this adhesion to metals.

  The ionomer resin used according to the invention

  tion is a thermoplastic resin obtained by copo-

  lymerization of olefin and carboxylic acid

  ethylenically unsaturated at a, B, and by neutralization

  of some or all of the car-

  resulting polyolefin boxyl with a metal such as sodium, potassium, magnesium or zinc so that the groups ionize. This resin has the property of dispersing spontaneously and easily in water, without the use of a surfactant with formation of an aqueous dispersion. This dispersion of the ionomeric resin is used alone or in admixture with a polyolefin resin having no such property of spontaneous dispersibility, prepared by simple uniform mixing with a compatible resin having a polar group or not, such as a copolymer

  ethylene and vinyl acetate or polyethylene.

  On the other hand, an aqueous dispersion of the polyolefin grafted with an ethylenically unsaturated carboxylic acid at a, B can be easily prepared by adding its melt to water

  containing a basic substance and under agitation

  (British Patent No. 1,517,828 provides details of its preparation process). when

  mixture of such a grafted polyolefin with a copolymer

  ethylene and vinyl acetate, a poly-

  ethylene, etc. is then treated in the same manner, an aqueous dispersion of the grafted polyolefin and such a polyolefin resin which does not disperse spontaneously, can be formed. More precisely,

  such a mixed aqueous dispersion can be easily

  formed by mixing 50 to 1 parts by weight of a polyolefin grafted with an ethylenically unsaturated carboxylic acid at a, c, having a subscript

  from about 30 to 150, and preferably

  between 50 and 130, with 50 to 99 parts by weight

  polyolefin resin compatible but not dispersible

  spontaneously sand, such as a copolymer of ethylene and vinyl acetate or polyethylene, by melting the mixture, and adding the molten uniform mixture into hot water containing a basic compound and

  with stirring. Thus, the mixed aqueous dispersion

  of the grafted polyolefin and the polyresin resin

  olefinic non-dispersible spontaneously can also be

  used as the aqueous dispersion of the polyresin resin

  olefinic dispersible spontaneously in the same manner as the aforementioned mixed aqueous dispersion of the ionomeric resin. The spontaneously nondispersible polyolefin resin which can be used in combination with the ionomer resin or the grafted polyolefin may be an olefin homopolymer or copolymer such as

  ethylene, propylene, butene-1 or methyl-4-

  pentene-1. Particular examples are the homo-

  polymers such as polyethylene, polypropylene, polybutene-1 and polymethyl-4-pentene-1 and resinous or rubbery copolymers such as copolymers of ethylene and propylene, copolymers of ethylene and butene-1, ethylene copolymers

  and butadiene, terpolymers of ethylene,

  ethylene, propylene and dicyclopentadiene terpolymers, terpolymers of ethylene, propylene and ethylidenenorbornene, copolymers of propylene and butene-1, copolymers of

  of propylene and butadiene, the copolymers of

  vinyl acetate and a product of saponifi-

  cation of these last copolymers. These resins can

  be used alone or in combination.

  When the aqueous dispersion of the resin

  spontaneously dispersible polyolefin at a concentration

  The solids content is generally from about 10 to about 60% by weight and preferably from about 20 to 50% by weight, and its viscosity is suitable for its coating, so that pitting can not occur in a film prepared by coating of the aqueous dispersion. Where appropriate, penetration

  of the aqueous dispersion in the paper can be

  at least by adjusting the viscosity using

a thickening agent.

  The aqueous dispersion prepared in the manner described above can be applied to the substrate

  paper, for example by coating

  spraying, calender coating, gravure coating, casting coating, scraping coating, etc. Usually, a single layer forms a metallized surface of low brightness and also tends to form a moisture-alterable product unless the surface of the substrate is smooth. Accordingly, it is usually desirable for the coating to be carried out two or more times until the coated surface has the desired regularity. For example, when the resin layer is to be applied at a rate of 6 to 8 g / m 2 to the paper substrate, the results obtained by three or four coating operations of the aqueous dispersion, each time forming a layer of resin. about 2 g / m 2 are better than those of the coating in one

  only once in the entire aqueous dispersion.

  The total amount of aqueous dispersion in the coating is not critical and may vary

  with the nature of the resin used, etc. He is in general

  advantageous that the total quantity

  between about 1 and 30 g / m and preferably between

  viron 2 and 20 g / m, this amount corresponding to the

applied resin.

  When the coating of the aqueous dispersion is carried out in two or more times, it is often noted that the dispersion applied to a layer of

  already formed resin undergoes a repulsion which makes it difficult

  the formation of a uniform coating, and the vacuum deposition of a metal on this non-uniform coating causes the formation of a metal layer

  no color and whose color varies and whitens

  time. This phenomenon may occur when an aqueous dispersion containing the polyolefinic resin

  modified by carboxyl groups, spontaneously dispersible

  neat and devoid of surfactant, is applied in two or more times. This phenomenon can be avoided by incorporation into the aqueous dispersion, at least

  after a first coating cycle, a wetting agent

  facilitating the wetting of the surface of the coating

  for example a nonionic surfactant such as polyoxyethylene lauryl ether, ether

  Polyoxyethylene sec-butyl, a block copolymer

  polyoxyethylene and polyoxypropylene, or polyoxyethylene nonylphenol. However, since such a surfactant is generally of low molecular weight and may volatilize during a

  vacuum operation used for metallizing

  tion, making it difficult to obtain a vacuum

  the amount of this wetting agent must be

  pick at least. Preferably this amount should

  be limited to a maximum of 5% by weight and preferably

  not more than 3% by weight, by weight

  of resin present in the aqueous dispersion.

  According to the invention, this inconvenience

  may be suppressed by the addition of polyalcohol

  vinylic to the aqueous solution. Polyvinyl alcohol

  that is suitable for this purpose is formed by saponifica-

  polyvinyl acetate, with a degree of saponin

  at least 75% and preferably at least%, and its viscosity, in the form of a 4% aqueous solution, is at least 3cP (at 200C) and preferably at 50cP ( at 200C). It is advantageous that the polyvinyl alcohol contains practically no impurities or volatile constituents.If necessary, the alcohol

  Polyvinyl may be used in the form of a copolymer

  a statistical mother whose comonomer is a car-

  Boxylic acid with unsaturation in OE, f, such as acid

  acrylic acid or maleic anhydride, or one of its

riveted, or ethylene.

  The amount of polyvinyl alcohol may in general be up to about 15% by weight and is preferably between about 0.03 and 10% by weight, preferably between 0.1 and 5% by weight by weight.

  relative to the resin weight of the aqueous dispersion.

  The coated aqueous dispersion is then

  dried. Drying can be done at room temperature

  biante but it is desirable that the drying temperature corresponds to the softening temperature of the coated resin or be higher, while being lower than the temperature at which the substrate of

  paper or resin coating degrades thermal-

  Typically, the temperature is usually below about C. The drying conditions also depend on the diameter of the resin particles in the aqueous dispersion. In general, the drying is advantageously carried out at a relatively high temperature when

  particle diameter is important and at a

  relatively low temperature when this diameter is small. In general, the drying can be carried out at a temperature of at least 1000 ° C, for a few seconds to a few minutes. When the coating is done in two or more times, the drying can be used at each layer. Drying can also be

  low temperature, after the first

  and the following, and at elevated temperatures,

  below the softening temperature of the resin,

  after the final layer. In this way, a cover-

  continuously of resin, the thickness of which is generally between about 1 and 30 microns and preferably between about 2 and 20 microns, may be

formed on the paper substrate.

  A metal is then deposited under vacuum on the resin coating itself formed on the substrate of

  paper. The term "metal" used in the present

  moire also means alloys. This vacuum deposition can be carried out in a known manner. For example, it can be achieved by heating a metal to be deposited at a temperature above its melting point.

  and under high vacuum, for example between 10 3 and 10 torr.

  Examples of metals that can be deposited are aluminum, tin, zinc, lead, copper, silver, gold, manganese, magnesium, brass,

  nickel, chromium, Ni-Cr alloy and Ni alloy

  Fe. The thickness of the deposited metal film is not essential and may vary according to the application of the final product. In general, the thickness is between about 100 and 1000 A and preferably between about 300 and 700 A. The adhesion of the resulting metal film

  to the paper substrate, through the coating

  resin, is good, and gives excellent results.

  satisfactory in the classic peeling test of a

adhesive tape.

  Metallic paper prepared according to the

  It has an excellent metallic luster and a very beautiful decorative appearance, as well as a low permeability to gas and humidity. It can be used very widely for example for the packaging of food materials, tobacco, medicines, etc. as well as in form

  labels, silver or gold threads, and conden-

on paper.

  Depending on the final applications,

  Possible elements are the embossing of the metalized surface, obtaining a transparency effect or

  semi-transparency, or the formation of a protective layer

  tended to prevent changes in color

  ration. When the metallized paper according to the invention, for example an aluminized paper, is used in the

  applications mentioned above, the aluminized surface is ha-

  usually processed, for example by printing,

  clothing of a resin or gluing of a plastic film. Thus, the aluminum surface must have characteristics that are suitable for such treatment,

  for example, characteristics allowing the printing

sion or collage ..

  The aluminum surface has a chemical activity

  intrinsic risk as well as a high

  age and good adhesion to inks or adhesives. In most cases, the papers

  aluminized materials are stored or used in the form of

  water or batteries. Under these conditions, the aluminum surface is in direct contact with the surface of the paper substrate of the metallized paper, and the good surface characteristics of the aluminum

can be degraded.

  As a result of various investigations into the cause of this phenomenon, the following fact has been demonstrated in the context of the invention. Each of the various substrates indicated in the following table, covers the aluminum surface of a metallized paper

  just after metallization, and then rest. Lors-

  that the substrate is formed of paper, the wetting tension of the aluminum surface is considerably reduced and the adhesion of the inks becomes poor. However, when the substrate is a polyester film allowing metallization, no phenomenon is noted. These results show that a substance that contaminates aluminum is present in the substrate paper (natural pulp paper) that comes into contact with the aluminum surface and, after contact, this substance migrates to the surface of the aluminum layer and thereby reduces the wetting tension and the fixing ability of

the aluminum surface.

TABLE I

  Substrate set Wetting tension- Contact adhesion (dyne / cm) coated paper ink (clay) 33 1 woodfree paper 34 1 imitation 33 1 polyester film> 56 5

  Note 1 the substrate is applied to the aluminum surface

  aluminized paper just after vacuum deposition, and the whole undergoes aging for three days in an oven at 40 ° C under a load of 5 g / cm 2

  it is used as a measurement sample.

  Note 2: The wetting tension is determined according to the

ASTM D 2578.

  Note 3: a white "GNCST" printing ink available

  Commercially available (produced by Toyo Ink Mfg., Co., Ltd.) is coated on the aluminum surface and then dried at room temperature. Cellophane tape was applied to the sample and peeled at an angle of 1800. The adhesion area of the ink was evaluated after the peel test using the following scale: Adhesion of Ink ink adhesion surface,%

5,100

$ 4 90 - <100

$ 3 75 - <90

2 50. - <75

1 - <50

  The invention also relates to the suppression of the cause of degradation of the characteristics of the surface of the aluminum-coated layer as a result of

  contact with the paper, and we notice more precisely

  the effectiveness of a protective layer intended to prevent the migration of the contaminant substance contained by the paper substrate, on the surface of

  this substrate which does not carry the aluminized layer.

  It is found that polyvinyl alcohol is a resin

  particularly effective for forming a cou-

  protector, unlike vinylidene chloride or acrylic emulsions

  whose effect is weak. It can be seen that alcohol

  lyvinyl has a sufficient effect even when it is

used in very small quantities.

  Thus, the invention also relates to a paper

  metallized material having a paper substrate, a thin coating

  continuous film-forming resin on a first side, a metallized film on the surface of the coating

  of resin, and a thin continuous coating formed in the

face of the paper substrate.

  The polyvinyl alcohol coating can

  be applied before or after vacuum metallization.

  It is generally convenient for a continuous thin layer of polyvinyl alcohol to be formed by applying an aqueous solution of polyvinyl alcohol prior to vacuum deposition on the face of the paper substrate which does not

  does not carry the continuous coating of the film-forming resin.

  Polyvinyl alcohol can be used

  has been described previously. The coating can be ef-

  made with an aqueous solution having a

  at a concentration of between about 1 and 20% by weight and preferably between 2 and 10% by weight, in one or more times, in a well-known manner, for example by spraying or applying to the calender. The

  total amount of coating material is

  taken generally between about 0.2 and 5 g / m 2 and preferably between about 0.3 and 1.0 g / m 2, these

  figures for solids only.

  So, a protective layer of alcohol

  polyvinyl the thickness of which is usually

  between about 0.2 and 5 microns and preferably between about 0.3 and 1.0 micron, can be formed on

one side of the paper substrate.

  When the resulting metallised paper,

  both the metallized layer, preferably aluminum,

  on a first face and a protective layer of

  cool polyvinyl on the other side, is put in red-

  water or in the form of a stack, the metallized surface of the paper is not in contact with the paper substrate but that of the polyvinyl alcohol layer formed on the other side of the paper substrate; the contaminant contained in the paper therefore no longer degrades the surface characteristics of the aluminum layer as its printing characteristics

and collage.

  Other features and advantages of the invention will be better understood when reading the

  following description of particular examples of

  implementation of the invention given purely

illustrative and not limiting.

EXAMPLE 1 TO 16

  Each of the aqueous dispersions is applied

  resins A to F described later in this document.

  by coating on the front side of a sheet of paper containing no wood (strength equal to 64 g / m) in the quantities indicated in Table A, in a number of times indicated in that same

  chart so that the paper is coated with

  sine whose thickness is between about 2 and 12 microns. The drying is carried out at 1200C for 5 s

Everytime.

  Aluminum (99.99% purity) is deposited on the surface of the paper resin coating

  resulting in a vacuum deposition device now

  4 n at a pressure of 10 torr, by carrying out a stripping resistance heating process, so that an aluminized film having a thickness of about 500 A is formed on the surface of the resin coating. The aqueous dispersions used for the formation of the resin coating on the paper do not

  containing no wood have the following compositions.

Aqueous dispersion A

  It is an aqueous dispersion whose

  The solids concentration is 35% by weight and is prepared by mechanical dispersion of a melted mixture of 90 parts by weight of polyethylene (density of 0.92 g / cm 3 and melt index of 23 g / 10 min). and a polyethylene grafted with acid

  acrylic acid (acid number 100, intrinsic viscosity

  sque measured in decalin solution of 0.8, and melting temperature of 1240C), with a mean particle diameter of about 10 microns, in water

  wherein potassium hydroxide is dissolved.

  Aqueous dispersion B This is an aqueous dispersion having a solids concentration of 27% by weight and

  a viscosity of 500 cP at 250C, and prepared by dispersing

  mechanical conversion of an ionomeric resin (sodium salt of a copolymer of ethylene and methacrylic acid, having a content of methacrylic acid units of 15% by weight, neutralized to 59 mol%, having a

  density of 0.95 g / cm, a temperature of

  870C and a melt index of 0.9 g / 10 min

  at 1900C, as determined according to ASTM D 1238-

  57T), having an average particle diameter of about

0.1 micron, in water.

Aqueous dispersion C

  It is an emulsion of a polymer of the type

  For example, vinylidene chloride (a copolymer of vinylidene chloride, butadiene and methyl acrylate, produced by Kureha Chemical Industry Co., Ltd.) having a solids concentration of 50% by weight.

  weight and commercially available.

  Aqueous dispersion D This is an emulsion of an acrylic polymer (copolymer of styrene, butyl acrylate and

  butyl methacrylate) having a concentration of

  42.5% by weight solid and commercially available. Aqueous dispersion E

  It is a rubber latex of copoly-

  mother of styrene and butadiene (produced by Nippon

  Zeon Co., Ltd), having a concentration of

  lides of 50% by weight and commercially available.

Aqueous dispersion F

  It is a rubber latex of copoly-

  mother of nitrile and butadiene (produced by Nippon

  Zeon Co., Ltd) having a concentration of solids

  equal to 50% by weight and commercially available.

  When applying the aqueous dispersion A or

  B in two or more times, laury ether is added

  polyoxyethylene to these dispersions when

  are applied during the second cycle and the cycles-

  following coating. The amount of lauryl ether

* polyoxyethylene is 0.2% of the weight of the dispersion

  in the case of dispersion A and 0.05% of the weight of the dispersion in the case of dispersion B. The properties of aluminized papers formed

  measured by implementing the following operations:

your.

(i) Peel strength.

  Cellophane tape is applied to the surface of the aluminized layer and peeled off to examine the adhesion of

the deposited layer.

(ii) Permeability to moisture.

  It is determined according to ASTM D1434-

  58 at a temperature of 40 C and with a humidity of

  lative 90% (the result is expressed in g / m

24 hour period).

(iii) Brilliant.

  It is measured using a "VG-107" instrument (instrument made by Nippon Denshoku Kogyo KK) of automatic type and variable angle, with a light projection angle of 45 and a light receiving angle of 45, according to ASTM

D1223-57T.

  The results obtained are shown in Table A. The aluminized papers retain practically the mechanical strength, the elongation and the hardness of the

  woodfree paper used as a substrate.

TABLE A

  Example Aqueous dispersion type total quantity applied number of cycles (amount of solids applied, g / m 2) Properties peel strength of aluminized paper permeability glossy to moisture (g / m.24 h) A il il B Il II! ' g B II l! I C I D E F I1 i

"8

"4

  He He Good He It He He IV If He There I I! Il Il Il Ir Non-treated woodfree paper Aluminum foil (10 micron thick)

(bright side

lante)

(other way

this) U1j Ln ru 0% Co

EXAMPLES 17 TO 23

  It is mechanically dispersed in water

  sodium ionomer (sodium salt of a copolymer of ethylene and methacrylic acid having a content of methacrylic acid units of 15% by weight, a density of 0.95 g / cm 3 and a degree of neutralization of 59 moles %) to prepare an aqueous dispersion having a solids concentration of 20% and containing resin particles of which

  the average diameter is about 0.1 micron. We say-

  separately from polyvinyl alcohol (type / H produced by Kuraray Co., Ltd, having a degree of polymerization of 1700, a degree of saponification of about 99.9% and a viscosity of about 30 cP in the form of a 4% aqueous solution) in

  water to form a 10% solution, and add it to

  to the aqueous dispersion of the ionomer resin pre-

  prepared as indicated, with the proportions shown in Table B. The resulting aqueous dispersion mixed in three times on one side of a paper without wood (strength 54 g / m 2) using a calender of

  at a rate of 2 g / m2 at each cycle of application.

  cation.The coating is dried at 120 ° C.

  for 5 s each time, and the woodfree paper ob-

  held at a resin layer whose thickness is

About 6 microns.

  Aluminum is then deposited under vacuum on the woodfree paper having the indicated coating,

  described in Examples 1 to 16 in a

  positive vacuum deposition maintained at a torr pressure, so that a film of aluminum is formed whose thickness is about 500 A on the face of the paper which is coated with the resin. The peel strength, moisture permeability and gloss of the resulting paper are measured in the same manner as in Examples 1 to 16. The results are shown in FIG.

Table-B.

TABLE B

  Example Composition of the applied film Properties of the (% by weight) resistance to the ion-alcohol resin polyvinyl mother-coat 99.97 99.95 99.9 0.003 0.05 0.1 good I. II, I, aluminized paper permeability glossy with moisture (g / m2)

300-400

  In Example 17, the gloss exhibits a

  range of variation. These results suggest a variation

  brilliance and the possible presence of a

  In the other examples, the repulsion phenomenon does not appear in Example 23. In Example 23, the deposited aluminum layer is whitened in a similar manner.

certain extent.

EXAMPLE 24

  A commercially available 5% aqueous solution of polyvinyl alcohol (C-15 type from Shinetsu Chemical Co. Ltd.) is applied in one operation.

  having a degree of saponification of 98.5% and a screw

  cosity of 22 cP in 4% aqueous solution) on one side of a commercially available clay-coated paper (manufactured by Fuji Kakoshi KK having a strength of about 52 g / m 2) at 0 , 1, 0.2, 0.3, 0.4 or 0.5 g / m, as solids, before drying for 10 s, by blowing hot air at 1200C against the coated side. A protective layer of polyvinyl alcohol whose thickness is between 0.1

  and about 0.5 micron is formed on the paper.

  The other side of the paper is then coated with a mixed aqueous dispersion obtained by adding

  0.1% by weight of the polyvinyl alcohol cited before

  to the same aqueous dispersion of ionic resin

  mother that in Examples 17 to 23, with a coating calender, in three times, at a rate of 2 g / m2 at each application cycle. At each cycle, the layer formed is dried at 120.degree. C. for 5 seconds. So,

  a resin coating about 6 microns thick

  he is formed on paper. Then, aluminum is vacuum deposited on the resin coating, in a deposition device maintained at 10-4 Torr, so that a 500A thick aluminum layer is formed. Aluminized surface has good peel strength, moisture permeability of 2 g / m2

by 24 h, and a brilliance of 700.

  Two samples are cut from the aluminized paper just after vacuum deposition and superimposed so that the aluminum layer is

  contact with the polyvinyl alcohol layer. I am

  on variations over time of the voltage

  wetting and adhesion of the ink to the

  aluminum face by carrying out operations

  described in the first table.

  The results are shown in Table C.

TABLE C

  Test Quantity App- Wetting Adhesion Tension of n0 plicated of the aluminum side the ink after

  APV, g / m2 (dyne / cm) after a 3 d of old

lissement period 1 d 3d 5d

1 0 34 33 33 3

2 0.1 36 34 33 2

3 0.2 42 36 34 4

4 0.3> 56 50 40 5

0.4> 56> 56 50 5

6 0.5> 56> 56> 56 5

  It is generally considered that, in practice, the wetting tension of the aluminum surface is at least 36 dyne / cm after a period of 3 days and advantageously a period of 5 days of maintenance at 400C. It appears that the aluminized paper according to the invention is satisfactory in practice when the applied amount of polyvinyl alcohol is as low as 0.2 g / m 2. Just after vacuum deposition, the

  aluminum surface has a higher wetting tension

greater than 56 dyne / cm.

EXAMPLES 25 TO 32

  A 5% aqueous solution of the

  cool polyvinyl used in Example 24 on one side of a paper imitation (chemical pulp 100%, force

  52 g / m2) in a single operation so that the polyalcohol

  vinylic is applied at a rate of 0.4 g / m. The coating is dried with hot air at 120 ° C. for 10 seconds so that the paper is coated with polyvinyl alcohol.

  whose thickness is about 0.4 micron.

  The other side of the paper is then coated, in four portions, with each of the aqueous dispersions A to F of Examples 1 to 16 and aqueous dispersions G and H indicated hereinafter, at a rate of 4 g / m 2. each application cycle, before drying in hot air at 1200C for 12 s. Aluminum is then deposited under vacuum on the coating of

  resin so that it forms a 600 A thick film.

  The properties of the aluminized papers formed in the same way as in Examples 1 to 16 are then determined, and the results are shown in FIG.

table D.

Water dispersion G

  It is an acrylic emulsion of a copo-

  styrene, methyl acrylate and butyl acrylate (produced by Nippon Carbide Co., Ltd, having

  a solids concentration of 45%).

Aqueous dispersion H

  It is an emulsion of polyethylene acetate

  vinyl (produced by Nippon Carbide Co., Ltd) having a solids concentration of 46%)

TABLE D

  Example Type of Properties aluminized dispersion paper gloss permeability resistance aqueous moisture peel (g / m.24 h) 25 A good 5,300

26 B "0.2 1100

27 C "0.4620

28 D 610 240

29 E "200 1020

30 F 150 500

31 G "68,780

32 H "19 1140

EXAMPLES 33 TO 41

  One side is coated with a polyvinyl alcohol imitation paper, as described in Example 24, and

  applies to the other side an aqueous dispersion of

  one of the ionomeric resins of Table E which follows (

  is a partial sodium salt of a copolymer of

  thylene and methacrylic acid). Aluminum

  is then deposited under vacuum on the coating

  sine so that it forms a layer 400 A thick.

  Table E shows the properties of the dis-

aqueous persians used.

TABLE E

  Designation of the aqueous dispersion I J K L M Properties of

Methacrylic acid content% by weight ionomer resin Degree of

  Neutral Melting Temperature, Cation, C mole% Properties of the aqueous dispersion

  viscosity-viscosity dimension

  ticular, pm cP tion, wt% 0.25 0.38 0.24 0.05 or co-o Co The application conditions and properties of metallized papers are shown in Table F.

- TABLE F

  Example Aqueous dispersion Properties of the paper

  type conditions of application permeability permeability gloss quantity number at total humidity of cy- 2 applied keys <g / m)

0 g / 2 of application

g / m cation

33 I 12 3 1,2 350

34 J i "0.9 440

K

36 L

37 M

38 "

39 he

"

41 "

EXAMPLE 42

  1.1 1.0 0.7 2.1 0.9 The polyvinyl alcohol used is applied

  in Example 24, at 0.4 g / m 2, on a first

  first face of an imitation paper available in the

  merce (produced by Kasuga Paper-Making Co., Ltd., having a force of 52 g / m 2 and a width of 700 mm) as shown in Example 24, so that the layer of polyvinyl alcohol applied has a thickness about 0.4 micron after drying. We apply to each other

  paper side a sodium salt of a copolymer of ethyl-

  and methacrylic acid, at a rate of 7 g / m, as shown in Example 24, so that the

  formed resin coating has a thickness of 7

  believe about. Aluminum is then deposited under vacuum on the resin coating so that it forms a go layer of 400 A thick. So, we prepare a paper

  aluminized having a length of 2000 m and is wound.

  This paper roll is left for 3 days

  in an atmosphere maintained at 40 ° C. Samples are taken

  paper rolls into corresponding positions.

  approximately one-third, one-half and two

  third of the diameter of the roll, on the periphery of this

  this. The wetting tensions of these samples are then measured and they are found to be equal to 52, 54 and 50 dyne / cm respectively.

EXAMPLES 43 TO 52

  A synthetic paste formed by

  a fibrous material which has suffered a fibrillation caused by

  high-density polyethylene (mass density)

  0.96 g / cm, melting temperature 130 ° C, and average fiber length 1.6 mm) and a paste

  natural in the form of a bleached kraft pulp of paper.

  The synthetic paste and the natural paste are mixed in the proportions indicated in Table G and

  forms a sheet by a wet type process.

  A resulting aqueous dispersion (having a particle diameter of about 0.1 micron and a solids concentration of about 25% by weight) of a sodium salt of a copolymer of ethylene and polyisocyanate is applied to a surface of the resulting paper. methacrylic acid (content of methacrylic acid units of 15% by weight, degree of neutralization of 59% and density of

  0.95 g / cm 3) containing about 0.05% by weight of the

  Polyvinyl cool used in Examples 17 to 23,

  two or four times at a rate of about 2 g / m2 of

  in each application cycle, before drying at 1100C for 20 s each time, so that the formed resin coating has a thickness of

About 4 to 8 microns.

  Aluminum is then deposited under vacuum on the resulting paper, having the resin coating, in a high vacuum device between 10 3 and -5.

  torr, so that an aluminum layer of

  o Thick 500 A thick is formed on the coating of

resin.

  The gloss and moisture permeability of each aluminized paper are measured as in Examples 1 to 16. Table G

indicates the results obtained.

  The aluminized paper obtained in Example 50 is punched with an elliptical shape, and molded at a temperature of 2000 ° C, during a continuous cycle.

  2 s, in a stamping molding machine pro-

  bottom (manufactured by Joh Gietz + Co, an automatic machine for forming paper plates). Thus, with a good yield, a plate of good

  quality having an irregular profile reproduces faithfully.

  Proportions of TABLE G Example mixing of pasta,% by weight Strength of sub- Number of cy- Properties of natural synthetic pulp paper strat of aluminized pasteboard, g / m gloss cation permeability humidity (g / m.24 h)

43 100 0 65 2 180 2

44 60 40 75 "170 5

50 50 70 200 10

46 25 75 37 "150 23

47 100 0 65 "580 1

48 60 40 75 "450 <1

49 50 50 70 "510 <1

25 75 37 "400 <1

51 10 90 270 "850 1

52 8 92 260 "630 <1

o o

Claims (33)

  Metallized paper, characterized in that it comprises a paper substrate, a thin continuous coating of a film-forming resin having a good adhesion to metals, on at least one of its faces,   and a metal film deposited on the coating of   sine. 2. Paper according to claim 1, characterized   in that the film-forming resin is a synthetic resin tick with a polar group.   3. Paper according to claim 2, characterized in that the polar group-containing synthetic resin is either in the form of at least one resin containing at least one polar group selected from the class which comprises the carboxyl, carboxylate and halogen groups. , acyloxy and nitrile, or a mixture of such a resin with a resin devoid of such a polar group. The paper of claim 2, characterized in that the polar group-containing synthetic resin comprises at least one resin selected from the group consisting of carboxyl group-modified olefinic resins, vinyl acetate resins, vinylidene chloride and acrylic resins.   5. Paper according to claim 2, characterized   in that the synthetic resin containing a group   is an olefinic resin modified by groups of pes carboxyl.   Paper according to claim 2, characterized in that the synthetic resin containing a group polar is an ionomeric resin.   Paper according to claim 2, characterized in that the synthetic resin containing a group   polar is a product based on a copolymer of ethyl-   and methacrylic acid, crosslinked by alkaline ions. 8. Paper according to claim 2, characterized in that the synthetic resin containing a group   polar is a copolymer of ethylene and methacrylic acid   crylic containing 5 to 45% by weight of methacrylic acid units of which. 30 to 80% are neutralized by a alkaline ion.   9. Paper according to claim 2, characterized in that the synthetic resin containing a polar group is a mixture of an unmodified polyolefin and a polyolefin grafted with a carboxylic acid   with ethylenic unsaturation at a.   10. Paper according to claim 2, characterized   in that the synthetic resin containing a group   is a mixture of 50 to 99 parts by weight of a polyolefinic resin and 50 to 1 parts by weight of an ethylenically unsaturated carboxylic acid   having an acid number between about 50 and 150.   11. Paper according to claim 1, characterized in that the film-forming resin contains at most 15% by weight of polyvinyl alcohol, relative to the weight of resin-.   12. Paper according to claim 1, characterized   in that the continuous coating of resin has a thick   between about 1 and 30 microns.   13. Paper according to claim 1, characterized in that the paper substrate is a paper of a natural paste, a synthetic paste or a mixture   a natural paste and a synthetic paste.   14. Paper according to claim 1, characterized   in that the metal film is an aluminum film.   15. Paper according to claim 1, characterized in that the metal film has a thickness of between about 100 and 1000 A. 16. Paper according to claim 1, characterized   in that the thin continuous coating of film-forming resin   gene carrying the metallized layer is formed on a first face of the paper substrate, and the other face i   of this substrate carries a thin continuous coating of cool polyvinyl.   17. Paper according to claim 16, characterized in that the thin coating of polyvinyl alcohol has a thickness between about 0.2 and 5 microns. 18. Process for manufacturing a metallized paper, characterized in that it comprises the application of a thin continuous coating of a film-forming resin, having a good adhesion to metals, on a first face of a paper substrate. at least then the deposit under   empty of a metal on the surface of the resin coating.   19. Process according to claim 18, characterized in that the continuous coating of resin is prepared by application of an aqueous dispersion of the resin   film-forming at the surface of the paper substrate.   20. Process according to claim 18, characterized   in that the film-forming resin is a synthetic resin than dispersible spontaneously.   21. Process according to claim 20, characterized in that the spontaneously dispersible resin is a ionomeric reane.   22. Process according to claim 20, characterized in that the spontaneously dispersible synthetic resin is a product based on a copolymer of ethylene and   of methacrylic acid, crosslinked by alkaline ions.   23. The method of claim 20, characterized in that the spontaneously dispersible synthetic resin is a copolymer of ethylene and methacrylic acid   containing 5 to 45% by weight of methacrylic acid units   that 30 to 80% are neutralized by an alkaline ion.   24. The method of claim 20, characterized in that the spontaneously dispersible synthetic resin is a mixture of an unmodified polyolefin and a   polyolefin grafted with an unsaturated carboxylic acid ethylenic ration in cx, 6.   25. Process according to claim 20, characterized in that the spontaneously dispersible synthetic resin is a mixture containing 50 to 99 parts by weight of a polyolefin resin and 50 to 1 parts by weight of a polyolefin resin.   polyolefin grafted with a carboxylic acid to   ethylenic turation at a, X, having an acid number Between about 50 and 150.   26. The method of claim 18, characterized in that the aqueous dispersion has a solids concentration of between about 10 and 60% by weight. 27. The method of claim 19, characterized in that the coating is applied at least twice. 28. Process according to claim 27, characterized in that the aqueous dispersion contains at most 5%   by weight of a nonionic surfactant or by   up to 15% by weight of polyvinyl alcohol, relative to to the weight of the resin.   29. The method of claim 27, characterized in that the aqueous dispersion contains about 0.03 to 10% by weight of polyvinyl alcohol relative to weight of the resin.   30. The method of claim 18, characterized in that the aqueous dispersion is applied so that the amount of solids coating is between about 1 and 30 g / m 31. The method of claim 19, characterized in that the applied aqueous dispersion is dried at the softening temperature of the resin contained in the aqueous dispersion, or at a temperature above high.   32. The method of claim 18, characterized in that, before deposition of a metal under vacuum, a thin continuous coating of polyvinyl alcohol is formed in   the face of the paper substrate that does not wear the -revê- continuously resin.   33. Process according to claim 32, characterized in that the polyvinyl alcohol is applied in a quantity of between approximately 0.2 and 5 g / m