Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
  • B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/001—Combinations of extrusion moulding with other shaping operations
  • B29C48/0018—Combinations of extrusion moulding with other shaping operations combined with shaping by orienting, stretching or shrinking, e.g. film blowing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/001—Combinations of extrusion moulding with other shaping operations
  • B29C48/002—Combinations of extrusion moulding with other shaping operations combined with surface shaping
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/07—Flat, e.g. panels
  • B29C48/08—Flat, e.g. panels flexible, e.g. films
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
  • B29C48/91—Heating, e.g. for cross linking
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
  • B29C48/911—Cooling
  • B29C48/9135—Cooling of flat articles, e.g. using specially adapted supporting means
  • B29C48/914—Cooling drums
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
  • B29C48/911—Cooling
  • B29C48/9135—Cooling of flat articles, e.g. using specially adapted supporting means
  • B29C48/915—Cooling of flat articles, e.g. using specially adapted supporting means with means for improving the adhesion to the supporting means
  • B29C48/9155—Pressure rollers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/005—Shaping by stretching, e.g. drawing through a die; Apparatus therefor characterised by the choice of materials
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92504—Controlled parameter
  • B29C2948/92704—Temperature
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92819—Location or phase of control
  • B29C2948/92923—Calibration, after-treatment or cooling zone
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
  • B29C35/16—Cooling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/04—Condition, form or state of moulded material or of the material to be shaped cellular or porous
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
  • B29K2105/16—Fillers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2305/00—Condition, form or state of the layers or laminate
  • B32B2305/02—Cellular or porous
  • B32B2305/026—Porous
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/724—Permeability to gases, adsorption
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/726—Permeability to liquids, absorption
  • B32B2307/7265—Non-permeable
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2309/00—Parameters for the laminating or treatment process; Apparatus details
  • B32B2309/02—Temperature
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment

Definitions

• the invention relates to flexible, flexible and breathable polyolefin microporous films, formed of at least one layer, permeable to gases and water vapors but impermeable to aqueous liquids, with high mechanical characteristics and a pleasant feel.
• the invention relates to a method for producing by extrusion casting of polyolefin microporous films. made up of at least one layer, films permeable to gases and water vapor, but impermeable to aqueous liquids, with high mechanical characteristics and a pleasant feel.
• the invention finally relates to the use of the aforementioned films alone or associated in complex form with other porous supports.
• the most conventional method for producing these microporous films consists in preparing a mixture formed by a matrix of thermoplastic polymers having elastic properties and a pulverulent filler, generally inorganic, in extruding by casting this mixture in the molten state , in the form of a thick web, to take up this thick web by means of a metal cylinder (the surface of which can be provided with patterns for effecting an embossing of the web) having a function of pre-stretching the molten sheet and its cooling, then stretching it at least uniaxially after having heated it to a temperature favorable for this operation, in order to achieve the desired film.
• a metal cylinder the surface of which can be provided with patterns for effecting an embossing of the web
• the grains of the inorganic filler dispersed within the matrix of thermoplastic polymers are at least partially separated from the polymeric material by a mechanical effect, creating micro-channels inside and through the thickness of the film.
• the choice of the hydrophobic nature of the polymer matrix as well as that of the inorganic filler, and in particular the size of its grains, the quality of the dispersion of the filler within the polymer matrix and the choice of the stretching rate applied to the sheet for the film formation, are all factors which favor the creation of these micro-channels (whose equivalent diameter is a few microns) and which give the film its porosity to gases and its impermeability to aqueous liquids.
• microporous breathable films have been the subject of numerous researches relating to:
• the polyolefin resin can comprise homopolymers such as polypropylene. low density polyethylene, linear low density polyethylene, high density polyethylene and polybutylene. copolymers such as the ethylene-propylene copolymer and the ethylene vinyl acetate copolymer, or mixtures of these polymers. Particularly preferred are polypropylene, low density polyethylene, linear low density polyethylene or high density polyethylene, or a mixture of two or more of these polymers;
• the inorganic filler is preferably barium sulfate or calcium carbonate.
• composition of the film formed which is a mixture of a single copolymer of ethylene and of alpha-olefin C to Cio and an inorganic filler (calcium carbonate); - and by the pattern of the embossing which appears to be a selection of geometric shape
• the molten mixture constituting the composition of the film is extruded by casting in the form of a thick and hot strip.
• This strip is almost simultaneously pre-stretched. cooled and embossed by means of a cylinder metallic cooling and embossing, provided with a surface pattern, reducing the thickness of the completely cooled strip to approximately 100-150 ⁇ m.
• the embossed strip resulting from the embossing operation does not yet have the desired characteristics for the microporous film such as, in particular, a small thickness, a microporosity giving it the ability to breathe while being impermeable to aqueous liquids, or properties mechanical necessary for its subsequent operation, it is subjected, after being heated to the appropriate temperature (by calendering for example) to a drawing operation between two pairs of rollers (forming a drawing bench) rotating at different speeds.
• the first pair of rollers constitutes the calling torque which simultaneously plays the role of delivering the embossed ribbon to be stretched and possibly of helping to maintain the sheet delivered at the desired temperature for drawing.
• the second pair of rollers constitutes the actual drawing torque of the embossed ribbon heated by applying to it the desired drawing rate, this rate being given by the ratio of the linear speeds delivered by the pair of drawing rollers and the torque of rollers.
• the film according to the method practiced can undergo a heat treatment, generally under tension to control its shrinkage.
• a heat treatment generally under tension to control its shrinkage.
• the constituent material of the strip which is initially in an almost isotropic state, undergoes internal physical modifications during these stages, in particular macromolecular deformations and / or a macromolecular orientation and / or an evolution of the crystallinity, which are fixed in the state, during cooling.
• the strip from the embossing-cooling is heated to best undergo the actual stretching step (between the two pairs of rollers), this heating appears to be still insufficient to completely free the material of the strip from its internal state. frozen by cooling.
• a first object of the invention is to provide an improved process for manufacturing a microporous film permeable to gases and water vapor and impermeable to aqueous liquids, at least monolayer, based on polyolefin;
• Another object of the invention is to provide a method of manufacturing a microporous film, at least monolayer having a physical state with a strong isotropic tendency at the end of the drawing of the cooled sheet, that is to say an essentially amorphous and homogeneous physical state;
• the process for producing a microporous film with a strong isotropic tendency permeable to gases and impermeable to aqueous liquids consisting of at least one layer, comprising the successive steps of:
• the cooling of the molten sheet pre-stretched by the drive cylinder is partial and limited in a controlled manner to a temperature lying in the temperature range necessary for its stretching.
• the microporous film permeable to gases and impermeable to aqueous media, is characterized by an isotropic, homogeneous and partly amorphous physical state.
• the sheet extruded by casting in at least one layer and pre-stretched is only partially cooled, and this in a controlled manner, by the drive cylinder, to be brought to a temperature lying in the desired temperature range for drawing said sheet, and giving it the most complete isotropy characteristics, manifested by less internal stresses
• the sheet extruded and pre -drawn is cooled without precaution and without limit, by the passage on the cooling and embossing cylinder and. therefore, must be warmed to the temperature necessary for its stretching to be able to be stretched: the stretched film resulting from the state of the art is only partially isotropic as revealed by its high shrinkage capacity.
• the polyolefinic microporous film according to the invention permeable to gases and water vapor, and impermeable to aqueous liquids, is composed of a polymer matrix comprising at least one polyolefinic polymer and at least one mineral and / or organic filler.
• the polyolefin microporous film according to the invention can comprise a single layer called the main layer or be formed from several layers assembled together, each layer being able to be produced from a particular composition which is specific to it.
• the microporous film according to the invention is formed from a single layer, obtained by stretching an extruded sheet containing a high filler content, this stretched layer must have excellent mechanical characteristics, in particular very good resistance to traction to undergo without damage the stresses to which it is subjected in its various applications.
• the polyolefinic matrix is essentially composed of at least one polymer meeting this requirement of excellent mechanical strength which for this reason requires a rather high density resulting "de facto" in a high melting point.
• this layer which is the seat of certain internal tensions, generated by the drawing operation, can have certain drawbacks during subsequent operations such as:
• the microporous film according to the invention may be formed from several layers, the main one having high mechanical strength (as mentioned in the case of a monolayer film) associated with at least one another so-called specific layer, the polyolefin matrix of which can be formed not only of the polymer or polymers involved in the formation of the main layer and secondary layers but also of at least one specific olefin polymer and / or copolymer by the effect provided to the layer specific container, such as:
• the polyolefin microporous film comprises a single so-called main layer, this layer is formulated so that it provides the film produced with the essential and maximum mechanical properties mentioned above.
• the polyolefinic matrix is formulated so that it provides the film produced with the essential and maximum mechanical properties mentioned above.
• a monolayer film in the case of a monolayer film, comprises one or more olefin polymers and / or copolymers obtained by polymerization in presence of catalysts of the ZIEGLER-NATTA type or of the metallocene type, used alone or as a mixture, chosen from the group consisting of plastomeric polyolefins that are the copolymers of ethylene and alpha-olefins. homopolymer polyethylenes (low radical density) or copolymers of ethylene and alpha-olefins (high density linear, low density linear, very low density linear), ethylene vinyl acetate copolymers (EVA). ethylene acrylate the (EMA).
• EMA ethylene acrylate the
• the polyolefins (non-polar) entering into the composition of the matrix have a density which is in the range 0.865 to 0.965 g / cm " 'and preferably in the range from 0.900 to 0.935 g / cm 3 .
• the filler of mineral origin used in the composition of the film according to the invention can be chosen from the group consisting of calcium carbonate, talc, a clay, kaolin, silica, diatomaceous earth, magnesium carbonate , barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, aluminum hydroxide magnesium hydroxide, calcium oxide, magnesium oxide zinc oxide, titanium oxide, alumina, mica, glass powder, a zeolite or the like, and preferably calcium carbonate and barium sulphate, used alone or as a mixture.
• the filler of organic origin entering into the composition of the film according to the invention can be chosen for example from the group consisting of cellulose powders, polymer powders, such as polyurethane, epoxy. of ABS. polyfluorinated. polyamides, polyesters or other polymers, some of these powders being prepared by cryogenic grinding, used alone or as a mixture.
• the particle size of the mineral and / or organic filler is generally chosen to be less than 40 ⁇ m and preferably between 0.5 and 10 ⁇ .
• the amount of filler used in the preparation of the film composition is generally between 50 and 500 parts by weight and preferably from 80 to 400 parts by weight per 100 parts by weight of the polyolefin matrix. it being understood that outside these extreme limits, the porosity of the film can be made insufficient by default of the load and the rigidity of the film made too high by excess of said load, causing, in the latter case. a difficult stretching operation.
• the mineral filler Before introducing it into the polyolefinic matrix. it may be advantageous to subject the mineral filler to a surface treatment using a well-known treatment agent, chosen from the group of fatty acids or their salts, silicone oils and silanes, this treatment promoting the good dispersion of the mineral filler within said matrix.
• a well-known treatment agent chosen from the group of fatty acids or their salts, silicone oils and silanes, this treatment promoting the good dispersion of the mineral filler within said matrix.
• a dispersing agent in small quantity
• a dispersing agent having the property of promoting the dispersion of the filler within the polyolefin matrix, of enabling the quantity of the filler in said matrix to be increased and to prevent the formation of agglomerates of filler grains in the sheet extruded by casting and then in the film obtained by stretching.
• Such agglomerates can be the cause of instantaneous drawbacks (tears) or later drawbacks (local macroporosities and passage of liquids) which are detrimental to the quality of the microporous film.
• Such an agent, used according to the invention can correspond to the following general formula which comprises at least one free acid function:
• x and y taking values such that their cumulation is included in the range 0 to 24,
• R is a linear or unsaturated, saturated or unsaturated alkyl radical, an aryl radical. an alk> 1- aryl radical, a saturated or unsaturated heterocycle. containing from 5 to 28 carbon atoms and preferably from 8 to 24 carbon atoms, or also a steroid radical.
• Said radical R can also be branched or not and / or comprise one or more functional groups of the halogen -OH type. -COOH, -COOR. -NO 2 . -NH 2 , -CONH ?, -CN, sulfonic, sulfuric. phosphonic, phosphoric. while Z can be one of the carboxylic functions. sulfonic. sulfuric, phosphonic. phosphoric.
• Z comprises several acid functions
• at least one of them is free, the others being able to be salified or esterified by means of an alcohol of formula R'-OH in which the radical R 'can be a carbon chain containing 1 to 4 carbon atoms or one of the radicals belonging to the group previously defined for R, the radical R 'being able to be identical to the radical R.
• agents for treating the mineral and / or organic charge and / or dispersing agents of said mineral and / or organic filler within the polyolefinic matrix contribute to obtaining the best dispersion of the filler in the polyolefinic matrix and thereby to increasing the drawing capacity of the film by further improving its fineness characteristics (reduction in final thickness, and in microporosity, more breathable film).
• the mixture formed by the polyolefin matrix and the filler can also receive other active agents such as lubricants, pigments, dyes, thermal stabilizers, photochemical stabilizers, flame retardants, plasticizers, antistatics. This mixture can lead, in particular, and preferably, to the production of a microporous bactericidal and acaricidal film by the introduction (into said mixture) of suitable biocidal agents.
• the composition of the main layer is the same as that stated in the case of a breathable monolayer microporous film.
• the other layer or layers called specific layers associated with the main layer are produced by means of particular compositions which differentiate them from the main layer and which can also differentiate them from one another in the case of a multi-layer film. each specific layer can have a particular function.
• the polyolefinic matrix of the specific layers is composed of at least one specific olefinic polymer and / or copolymer by the effect which it gives to the layer containing it, and more especially the polyolefins of very low density (0.865 to 0.915 g / cm3) and / or low melting point (60 to 100 ° C).
• polyolefins of higher density from 0.920 to 0.965 g / cm 1
• high melting point from 100 to 160 ° C
• polyolefins with polar tendency in particular ethylene-acetate copolymers of vinyl, ethylene methyl acrylate. ethylene ethyl acrylate. ethylene acrylic acid, ionomers.
• polyolefins modifying the surface condition of the layer in particular to allow good adhesion with polar products such as cellulosic fibers (paper), polyester fibers, viscose fibers and others.
• the polyolefinic matrix of the specific layers can also comprise the olefinic polymer (s) and / or copolymers entering said main layer.
• the polyolefin matrix of each specific layer consists of 5% to 100% by weight, and preferably, from 15% to 100% by weight relative to the total mass of said matrix of at least one specific olefin polymer and / or copolymer and at most 95%, and preferably, 85% of at least one olefinic polymer and / or copolymer entering into the composition of the matrix of the main layer.
• the layers other than the main layer may also contain at least one mineral and / or organic filler chosen from the groups mentioned above and in quantities chosen in the intervals also already mentioned in the case of the main layer.
• the preparation of the mixture according to the invention comprising a polyolefinic matrix and an inorganic and / or organic filler, can be carried out according to known methods, it being understood that the means used for the application of these methods well lead to obtaining a molten mixture by casting extrusion in which the mineral and / or organic filler is correctly dispersed, that is to say free of agglomerates.
• One of the methods may consist in using the various constituents in a twin-screw extruder with multiple feeds and in extruding the molten mixture by casting.
• Another method can consist in carrying out the preparation by extrusion of granules of a masterbatch by dispersing the charge in a fraction of the polymers constituting the polyolefinic matrix, then in diluting this masterbatch in the remaining fraction of the polyolefinic matrix. or to use a masterbatch representing the essential part of the composition, and to extrude the molten mixture by casting.
• the molten mixture is hot extruded by casting through a flat die, to form a molten sheet by means of the polyolefin matrix. with a thickness between 300 and 2000 ⁇ m at the outlet of the die.
• the temperature of the die and of the melted sheet at the time of extrusion is between 170 ° C and 270 ° C.
• the thick web formed is pre-stretched by a drive cylinder, of generally metallic surface, associated with a counter-cylinder of rubberized surface for example, or with an air knife, by subjecting it to a stretching whose ratio is generally between 4 and 25, and preferably between 5 and 10 between the outlet of the extrusion die and the coming into contact of the drive cylinder.
• the web pre-stretched by the drive cylinder is partially cooled there in contact with it to the temperature necessary for its subsequent stretching, simultaneously solidified in a controlled manner. To do this, the temperature of the cylinder is adjusted so that the temperature of the sheet in contact with it is brought by controlled cooling to the temperature necessary for its drawing.
• the temperature given to the sheet in contact with the drive cylinder is chosen in the range of 40 ° C to 165 ° C and. preferentially. in the range of 55 ° C to 135 ° C.
• the surface of the web drive cylinder may be a smooth surface of the glossy or matt type.
• the surface of said cylinder can be formed from a surface structure with a high coefficient of friction, either by the material used. for said surface, either by creating on this surface a regular or irregular, or even random, structure of the surface, such as for example a sanded, satin, dotted, or other aspect.
• said sheet can also undergo an embossing operation by means of said cylinder.
• the surface of the drive cylinder is provided with a regular or irregular pattern, in relief or in hollow, the most frequent shapes of which may be lines in the longitudinal direction, transverse, diagonal to the direction of advancement of the tablecloth, parallel or intersecting to form geometric figures, more or less open rafters, sinusoids, teeth, or even figures such as polygonal or circular (hexagon, rhombus, circle, for example) , or random distribution figures.
• the contact time of the web with the drive cylinder which allows it to be placed at the best temperature level for drawing by its controlled cooling can be adjusted by the use of a counter cylinder placed in the tangential outlet zone of said tablecloth.
• This counter cylinder makes it possible to fix the length of the arc of contact of the ply with the drive cylinder, that is to say to adjust the extent of the embracing of the cylinder by the ply by imposing on it the moment of exit tangential of said cylinder.
• the web is best prepared to undergo stretching in the best conditions.
• the stretching of the pre-stretched sheet. brought to the desired temperature (for said stretching) in contact with the drive cylinder by partial cooling, adjusted and controlled, is immediately carried out in a single step by traction by means of a pair of rollers at the instant when the web at adequate temperature separates tangentially from said drive cylinder.
• the cylinder d drive of the sheet also ensuring its pre-stretching, its partial cooling, adjusted and controlled, also plays the role of call cylinder delivering the sheet to be stretched when it has been brought to the most favorable temperature for this surgery.
• the web to be stretched is taken up by a pair of rollers, placed downstream of said cylinder, which constitutes the actual drawing torque of the web delivered by applying to it the desired stretching rate.
• This pair of drawing rollers placed downstream of the drive cylinder, is brought to a temperature between 40 ° C and 165 ° C and preferably between 55 ° C and 135 ° C: this temperature can be the same or different that of the drive cylinder.
• the stretching rate according to the invention given by the ratio of the linear speeds delivered by the couple of the stretching rollers and the drive cylinder (pre-stretching, cooling and drawing) of the web brought to the suitable temperature for stretching is chosen in the range from 1.5 to 10 and preferably chosen in the range from 2 to 6. But it is also possible, according to the invention, that the stretching of the web (pre-stretched). brought to the desired temperature by partial cooling, adjusted and controlled in contact with the drive cylinder, takes place in several successive stages.
• the first stretching step is immediately carried out (as previously mentioned) by traction using a pair of rollers placed downstream of the drive cylinder where the web (which is placed at the appropriate stretching temperature between 40 ° C and 165 ° C) tangentially separates from said drive cylinder.
• the stretching of the web, in this first step represents a fraction of the total desired stretching: this fraction is between 80% and 20% of the total stretching envisaged.
• the partially stretched film can undergo relaxation by passing over an appropriate cylinder (called relaxation cylinder) the temperature of which is chosen in the range from 125 ° C. to 20 ° C.
• relaxation cylinder the temperature of which is chosen in the range from 125 ° C. to 20 ° C.
• the relaxed film is reheated and brought to the desired temperature by passing over a reheating cylinder, for the continuation and / or completion of the stretching: the reheating temperature of the partially stretched film at during the first stage is chosen in the range of 40 ° C to 165 ° C the output of the reheating cylinder, the partially stretched film, brought to the desired temperature for further stretching, enters a zone of conventional stretching which comprises two pairs of rollers rotating at different speeds, one for drawing and the other for stretching the web: in this conventional stretching zone, the stretching of the film can be completed.
• the stretching fraction practiced in the second stage is between 20% and 80% of the total stretching envisaged.
• the stretching fraction practiced in the first stage is between 20% and 70% of the total stretching envisaged
• the stretching fraction practiced in the second stage is between 15% and 70% of the total stretching envisaged
• the stretching fraction practiced in the other stages, including the final stage of stretching (by sharing) is between 15% and 70 % of the total stretch envisaged.
• the same means as previously mentioned are found, of relaxation of the film, reheating the film, stretching the film and relaxation-cooling of the film in the end, means which are repeated as many times as there are stretching steps.
• the complete cooling of the microporous film at the drawing outlet can be ensured by an appropriate relaxation or cooling station, formed for example of one or more cascade cylinders, providing a decreasing temperature to the temperature desired by the storage. .
• the pre-stretched sheet is bluntly cooled by the drive cylinder to a temperature lower than that necessary for drawing and is subsequently reheated to the drawing temperature in order to be able to to be stretched.
• the stretching method practiced according to the invention is much milder than that practiced in the prior art.
• the film can undergo an embossing operation in various zones of the process according to the invention.
• the film can undergo an embossing operation in one and / or the other following zone (s) of said process. a) in the tangential stretching zone, using the pair of web stretching rollers, placed downstream of said drive cylinder, as an embossing means, d) in the relaxation zone of the stretched film, using at least one of the relaxation cylinders as embossing means, the film can undergo an embossing operation in one and / or the other (s) following zones of said process: a) in the tangential stretching zone using, as previously expressed, the pair of rolls for drawing the web, placed downstream of said drive cylinder, as an embossing means.
• the film can be embossed in the stretching, relaxation, reheating and relaxation-cooling zones, via the surface of at least one rollers of the stretching and / or drawing pairs, relaxation and / or reheating and / or relaxation-cooling cylinders: the surface of the roller (s) and / or of the cylinder (s) intended for embossing the film is provided of a regular or irregular pattern, in relief and ' or hollow, the most frequent shapes of which may be, for example, lines in the longitudinal direction, transverse, diagonal to the direction of advancement of the film, parallel or intersecting to form geometric figures, more or less open rafters, sinusoids, teeth, or even figures such as polygonal or circular (hexagon. rhombus, circle) or random distribution figures.
• this embossing can be carried out once or several times in the process according to the invention.
• the embossing When the embossing is done only once, it can be done on the web before stretching by means of the drive cylinder (zone a)) or on the film in one of the zones b) or c) or d) previously mentioned.
• embossing When embossing is done several times, it can be done by combining, for example: the embossing of the web (zone a)) with the embossing of the film in at least one of zones b), c), d) , - the embossing of the single film by combining at least two of the embossing zones b), c). d).
• the microporous film according to the invention being stretched in the longitudinal direction can also undergo beyond this first stretching another stretching, but transverse.
• the transverse stretching is practiced by means of known devices, with a stretching ratio generally between 1, 1 and 10 and preferably between 1.1 and 4.
• the method according to the invention leads to a reduction of the stretching efforts thanks to a stretching carried out at the most favorable temperature without having subjected it to an uncontrolled cooling followed by significant heating to satisfy the thermal conditions of the drawing.
• this film is produced by means of a single extruder feeding the flat extrusion die by casting;
• the film can be produced by means of several extruders. That is to say as many extruders as there are layer compositions, which feed a flat die provided with a coextrusion device.
• the molten sheet formed of several layers coextruded by casting, then undergoes the same steps as those mentioned for the formation of a monolayer microporous film, that is to say:
• this ratio is equal to 1. In the case of a film completely oriented in the machine direction, that is to say non-isotropic, this ratio tends towards infinity.
• the index of the film according to the invention is always between the value 1 and the value of the index of the film produced according to the state of the art.
• the index of the film according to the invention is 1.4 to 2 times lower than the index of the film according to the state of the art and tends towards the value 1, showing its capacity to be more isotropic than films according to the state of the art.
• the microporous film according to the invention can be used alone or combined with other porous supports, such as, for example, non-woven fabrics, woven fabrics, knits, mesh-type meshes, paper, for applications miscellaneous such as personal care articles, dressings, medical articles, protective clothing, sports clothing, insulating coatings in construction, and others.
• the molten mixture consisting of the polyolefin matrix and the filler is used by extrusion. through the flat die (1) at the temperature proper to said mixture.
• the thick web formed (2) is pre-stretched by the drive cylinder (3) with a matified metallic surface associated with a counter cylinder (4) with a rubberized surface, according to an appropriate and chosen stretch.
• the surface of the drive cylinder can be provided with a regular or irregular pattern, recessed or in relief, to allow the embossing of the web.
• the pre-stretched web (2) by the drive cylinder is partially cooled there in contact with it to the temperature necessary for the first step of a two-step stretch.
• the contact time of the ply (5) with the drive cylinder (3) is adjusted by the counter cylinder (6) which. according to its position, increases or decreases the length of the arc for embracing the cylinder (3) by the ply (5): the tangential exit from the ply (5) is controlled by the counter cylinder (6).
• the sheet to be stretched (5) is taken up by a pair of rollers (8) and (9), placed downstream of said cylinder (3) which constitutes the tangential stretching torque of the first partial stretching step, applying the desired stretching rate to it.
• the ply (5) is stretched according to the film (7), between the drive cylinder (3) and the pair of rollers (8) and (9).
• the cylindrical surface of at least one of the rollers (8) and (9) can be provided with patterns, as previously mentioned, to allow the film to be embossed.
• the partially stretched film (10) undergoes relaxation by passing over the cylinder (11), the temperature of which is adjusted in the interval mentioned above.
• the relaxed film (10) is reheated on the cylinder (12) and brought into contact with it at the desired temperature to complete its stretching in a second step.
• the temperature of the cylinder (12) is adjusted to a value chosen in the interval previously mentioned.
• the cylindrical surface of the cylinder (12) can be provided with patterns, as previously mentioned, to allow the film to be embossed when it is reheated.
• the cylinder can be provided with a counter-cylinder with a rubberized surface (not shown).
• the cylindrical surface of at least one of the rollers (14) and (15) and / or the rollers (17) and (18) can be provided with hollow or raised patterns (as indicated above) to allow the film embossing.
• the stretched film (19) enters a relaxation station comprising in cascade the cylinders (20), (21) and (22 ) delivering the film (23) stretched and optionally embossed, at a temperature chosen for its storage on a reel.
• the cylindrical surface of the cylinder (20) can be provided with patterns such as those previously indicated, to allow embossing of the film beyond the final stretching step.
• the embossing can be carried out either on the web, or on the film, or successively on the web and then the film, in as many steps deemed desirable for the final quality of the film.
• a drive-cooling-embossing cylinder (diameter 125 mm) and a rubber counter-cylinder (diameter 125 mm).
• composition of the three films was the same: it consisted of a mixture of a polyolefinic matrix and a CaCO 3 charge (of diameter between 1 and 5 ⁇ m) at a rate of 1 10 parts by weight of the charge per 100 parts by weight of the matrix.
• the polyolefinic matrix was formed of:
• LDPE LDPE and a copolymer of ethylene and 42.6% of alpha-olefin constituting the polyolefin part of the masterbatch marketed under the reference AMPACET 100196 by the company AMPACET EUROPE.
• the film (reference 3) according to the invention was partially cooled on the drive-cooling-embossing cylinder to the temperature of 60 ° C desired for stretching and immediately stretched to this temperature at a rate of 4 from the tangential outlet of said cylinder regulated by the presence of a counter cylinder.
• the films (references 1 and 2) were cooled on the drive-cooling-embossing cylinder to a temperature of 30 ° C. and then, after leaving the cooling zone, were reheated to 60 ° C. for the reference film 1. 80 ° C for the reference film 2, and drawn at these temperatures at a rate of 4 on an appropriate drawing bench. All the physical properties of the films, as well as the corresponding index, have been collated in Table 1 below.
• the main (internal) layer of the finished film was 20 ⁇ m thick while the specific (external) layers each had a thickness of 2.5 ⁇ m.
• the two specific (external) layers of the same composition they also consisted of a polyolefin matrix, a mineral filler and various specific agents, the mineral filler being present in the mixture at a rate of
• the mineral charge was composed of CaCO 3 , the grains of which had a diameter between 1 ⁇ m and 5 ⁇ m.
• the temperature of the flat die as well as of the three-layer sheet extruded by casting was around 200 ° C., and the lip of the die open between 0.3 and 2 mm.
• the thinning of the three-layer sheet was approximately 10 times.
• the temperature of the metallic drive cylinder was adjusted to 65 ° C, so that the sheet was brought to this same temperature.
• microporous film thus obtained was not further processed: it was cut in line and then wound up for its applications.

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• Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
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• 1998
  • 1998-07-24 BE BE9800562A patent/BE1012087A4/fr not_active IP Right Cessation
• 1999
  • 1999-07-22 BR BR9912357-6A patent/BR9912357A/pt not_active IP Right Cessation
  • 1999-07-22 EP EP99929638A patent/EP1114082A1/de not_active Withdrawn
  • 1999-07-22 AU AU46414/99A patent/AU4641499A/en not_active Abandoned
  • 1999-07-22 US US09/744,403 patent/US6676871B1/en not_active Expired - Fee Related
  • 1999-07-22 WO PCT/IB1999/001308 patent/WO2000005295A1/fr not_active Ceased

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