SK127794A3 - Polymeric articles and materials - Google Patents

Abstract

Improvements in the manufacture of multi-layer organic polymer composites are described, particularly applicable to composites including adjacent layers of a relatively water-soluble polymer (e.g. partially hydrolysed polyvinyl alcohol) and a relatively water-insoluble polymer (e.g. fully hydrolysed polyvinyl alcohol). The extruded layers are brought together within the die housing or by nipping means external to the die, or the relatively water-insoluble layer may be coated onto the relatively water-soluble layer. Specific designs of die are claimed, as are specific extrudable compositions and apparatus for conveying the same to the dies. The invention makes available for the first time a range of articles in which plastic parts are water-compatible in normal use but are completely degradable on contact with water during disposal, such as WC-disposable sanitary articles and water-degradable rigid containers for oil and petrol.

Description

The invention relates to polymeric materials and articles made therefrom, and to methods and apparatus for forming polymeric articles and materials, particularly those polymeric materials and articles that can be easily disposed of when they are no longer needed.

Do t e r and later. with. The technique used is vinyl alcohol. which leads the reaction up to the groups, increases the alcohol and considerably

Polyvinyl acetate is a water-insoluble polymer produced by polymerizing vinyl acetate. This polymer for the production of polyvinyl alcohol (PVA) by a process of hydrolysis or alcoholysis by which acetyl groups are removed from polyvinyl acetate. The actual removal of the acetyl groups can be conducted in such a way that the resulting product is a copolymer of vinyl alcohol and vinyl acetate. When vinyl alcohol predominates but a significant amount of vinyl acetate is present in the polymer, the resulting polymer is cold water soluble and is often referred to as a partially hydrolysable poly. The residual vinyl acetate content is typically 11% by weight, corresponding to 12 mol%. In the case where the acetylocrystallinity of the thus prepared polymers decreases its solubility in cold water almost completely. A material of this type is referred to as fully hydrolysable polyvinyl alcohol. The residual vinyl acetate content does not normally exceed 3 mol%.

WO 92/01556 (the disclosure of which is incorporated herein by reference) discloses certain degradable products, usually in the form of films, in which a water-soluble PVA substrate is protected on its surface against contact with water, while the article is used as a polymer composite structure. However, such structures have so far been relatively difficult to prepare. It has been found that this particular melt-compression and blow-coextrusion process described and protected in WO 92/01556 does not provide a satisfactory product.

It is an object of the present invention to provide improvements in the shaping of the polymeric materials disclosed in WO 92/01556.

The invention is based on the unexpected and surprising discovery that a polymeric material of the type as described in WO 92/01556 can be prepared even more advantageously in terms of efficiency, speed and cost by extruding the film using a special die assembly or a special multi-stage molding process. Said flat die coextrusion is by no means applied to the nonextrusion melt-molding processes described in WO 92/01556, as will be explained in many details below.

Basis t a_. y y n álgz u

The above drawbacks eliminate polymer products and materials for making them, based on the fact that in one process, a composite polymer product or polymer material containing a first organic polymer layer (e.g., partially hydrolyzed polyvinyl alcohol) that is water-soluble is prepared in one process at a given (normally low) temperature, typically 20 ° C, and a second organic polymer layer (e.g., a fully hydrolyzable polyvinyl alcohol) adjacent the layer of the first polymer, the second polymer being substantially less soluble than the first polymer, possibly even insoluble in water at the given temperature. The manufacturing process consists of or blowing a film or coextrusion through a flat die through which the polymers are extruded through the overhead assembly so that they are discharged from the device as a composite polymer material containing polymer layers; or from the extrusion-lamination process, wherein the polymers are extruded through separate nozzles and the extruded films are then bonded together in a presser under conditions that allow lamination of one layer to another to form a composite polymer comprising layers of polymers; or from a molding and coating process in which the first polymer layer is extruded or blow molded and the second polymer layer is then applied in the form of a coating (e.g.

- 3 spraying, dipping, painting, rolling, etc.).

Where the article or material is blown into a film, the extruder head may include a first inlet of one of the polymers under pressure; a second inlet for inlet of another polymer under pressure; a composite mandrel wherein the first portion of the mandrel assembly is hollow along its entire length so as to encircle the second portion of the mandrel assembly and the entire assembly is such that the first annular channel is defined around the outer periphery of the first portion of the mandrel assembly to distribute one of said organic polymers an outer surface of the first assembly member and a second annular channel being defined around the outer periphery of the second portion of the mandrel assembly to distribute a second of said organic polymers along the outer surface of the second member of the mandrel assembly, the arrangement further comprising a guide channel connected to one or each of the channels for distributing the polymer from a respective lead to a respective channel around substantially the entire outer periphery of the respective portion of the mandrel assembly.

Such a head assembly for coextrusion of this material is new and constitutes another feature of the present invention. The present invention therefore provides, in a further aspect, a head assembly for coextruding a composite polymer article or material comprising first and second organic polymer layers adjacent to each other, and said head assembly comprising: an elongated housing with a first inlet for the inlet of one of the polymers under pressure ; a second inlet to the inlet of another polymer under pressure and an outlet downstream of the inlets to the outlet of the composite material; and a composite mandrel assembly within the housing, wherein the first mandrel assembly portion is hollow along its entire length such that it surrounds the second mandrel assembly portion and the entire assembly arrangement is such that the first annular channel is defined around the outer periphery of the first mandrel assembly portion to distribute one of said organic polymers along the outer surface of the first mandrel assembly towards the outlet opening of the housing, and a second annular channel extending around the outer periphery of the second portion of the mandrel assembly to distribute a second of said organic polymers along the outer surface of the second mandrel assembly toward the outlet opening of the housing , the first and second manifolds are terminated together in such a way that the two polymers are extruded from the housing outlet as a composite polymer material comprising polymer layers; the arrangement further comprising a guide channel connected to one or each of the manifold channels and preferably having a relatively greater width than the respective polymer manifold channel from the respective housing inlet to the respective channel around substantially the entire circumference of the respective portion of the mandrel assembly.

Preferably, the guide channel is associated with both channels, and more preferably each guide channel provides two paths for the polymer inlet through the respective inlet; namely, a first polymer transport path in one direction around the mandrel and a second polymer transport path in the second direction around the mandrel. In this most advantageous configuration, each road surrounds half of the spike and meets behind the spike (seen from the inlet).

The guide channels are preferably formed in the outer surface of the mandrels. Preferably, the width of the guide channels narrows downwardly from the inlet, most preferably up to a width identical to the distribution being supplied.

Most preferably, each guide channel is open along its entire length for the distribution to be supplied.

It is further preferred that each guide channel spirally turns forward (i.e., downstream) along its respective mandrel so that a polymer that has already passed along the channel to the rear of the mandrel (seen from the inlet) is prior to entering the respective mandrel. of the manifold substantially at the same or a similar longitudinal distance along the mandrel as the polymer that entered the manifold relatively soon after entering the assembly through the respective inlet.

Preferably, the second portion of the mandrel assembly may be hollow so that compressed air can be blown through the center of the extrusion head to expand the film upon exiting the head.

If the film is formed / manufactured by coextrusion through a flat die or by extrusion through a flat die of two separate films and subsequent pressing lamination, the extrusion die or die may comprise a first inlet for the inlet of one of the polymers under pressure; and a second inlet to the inlet of the second of the polymers with

under pressure, and respective elongate slits in the die or die through which each film is extruded.

Such a coextrusion head assembly is also new and constitutes another part of the invention. Accordingly, the present invention provides, in a further aspect, a head assembly for coextruding a composite polymer article or material comprising first and second organic polymer layers adjacent to each other and the head assembly comprising: a housing with a first inlet for the inlet of one of the polymers under pressure; a second inlet to the inlet of another polymer under pressure and an outlet downstream of the inlets to the outlet of the composite polymer material; head formulations defining a first elongate slot opening and a first distributor channel connecting the first inlet to said first slot opening, the distributor channel extending towards the slot opening and adapted to extend the polymer from one side to the other of the slot opening nozzle; head formulations defining a second longitudinal slot opening and a second distributor channel connecting the second inlet to said second slot opening, the distributor channel extending towards the slot opening and adapted to extend the polymer from one side to the other of the slot opening nozzle; the first and second apertures are terminated together in such a manner that the two polymers exit together from the housing outlet as a composite material comprising two polymer layers.

To effectuate the extrusion of the separated films through a flat die and subsequent lamination, the head assembly may preferably be an appropriate number of conventional flat die which provides the appropriate number of slit die openings with their feed lines, depending on the number of layers required in the composite material.

Thus, in conventional extrusion processes through a flat die of a single thermoplastic film, e.g. a rigid PVC film, the extrudable polymer composition is fed into a so-called " a hollow head or fish tail shaped head whose inlet channel of relatively large diameter rapidly expands into the guide channel to spread the extrudable composition across the nozzle (from one side to the other) of one slot head. The distributor channel is configured to promote the spreading of the composition towards the extreme portions of the slit head. The slot width is suitably adjustable by means of externally (externally) adjustable screws. The extruded film material is typically drawn under a suitable tension and passing conventional rollers and slicers for finishing.

In the case where the blended polymer is prepared by extrusion of separate layers followed by pressure lamination, this is done by pressure rollers, preferably at elevated temperature. Surface phenomena between polymers and / or electrostatic effects and / or external air pressure effects are generally factors conducive to lamination, so that the use of adhesives or surface melting of the individual layers at their phase boundaries is not required.

In the case where a molding or coating process is used to produce the desired products or materials from the blended polymer, the first polymer layer (relatively water-soluble) is extruded or blow molded by conventional methods and the second (relatively water-soluble) polymer layer is applied as a deposit in conventional ways. In particular, the application of a liquid mixture of the second polymer in the form of a spray is an acid.

Further, from this aspect, as a modification of the present invention, the layer of the second polymer may be replaced by a dried paint coat that dissolves significantly more slowly than the first polymer (or not at all) at a given temperature (e.g., 20 ° C). Said method is particularly suitable for the production of degradable rigid containers and bottles from the first (relatively water-soluble) polymer by blow molding, for storing water-free materials such as e.g. oil or petrol. Externally, these products are coated with a water-insoluble film to protect them from water degradation in use.

The products and materials described in the foregoing sections are novel in themselves, and these, including the method of manufacture thereof, constitute a distinctive feature of the present invention.

Another aspect of the present invention is a polymeric material or polymeric article consisting of a polymer at a given (usually low) temperature, typically 20 ° C, water-soluble, wherein the surface of the article or material is partially or fully coated with a coating that is significantly less or almost nothing at all. insoluble in water at a given temperature, providing a water resistant coating.

By analogy to the composites described herein, where a product or material is only partially coated with an ink, under a coated portion of the surface of a product or material, all the portion of the surface that is expected to be or is expected to be exposed to water during normal use of the product.

The products or materials are suitably formed from the starting polymer by conventional conventional methods, such as e.g. extrusion, molding, blow molding, casting, and depositing are then applied in liquid form (e.g., by spraying, dipping, painting or rolling, e.g., using a conventional printing machine) and then dried.

The soluble polymer is preferably partially hydrolyzed polyvinyl alcohol.

The protective coating is preferably a dried residue of an alcoholic solution of a liquid flexographic printing ink not containing CO-groups, such as commercially available inks for flexo printing polyolefin films. The ink sold under the trademark ORION, manufactured by Coates Lorilleux Limited, Essex, England, can be considered as a particularly suitable example of liquid inks from which ink deposition can be obtained by the process of the invention.

In certain embodiments of the invention, the article or material is laminar. Such a form according to the invention may be a polymer film or film commonly used in industrial manufacturing processes. Other forms of the invention are products consisting of pieces of such a polymeric sheath or film, wherein the flat pieces are deformed to obtain curvature in more than one direction. Examples are e.g. bottles.

If the unprotected surface of the polymer is exposed to water, it dissolves, but in places where the surface of the polymer is covered by a colored layer, such surface is protected. The ink acts as a protective coating and protects the first polymer against dissolution if the original protective surface has become wet.

Such ability has a wide range of applications. In general, the products and materials of the invention may be used wherever the color layer is believed to act as a barrier to protect the water-soluble polymer from a material that is or could be wet. Later, the exposed surface of the water-soluble polymer is allowed to come into contact with water. As a result, dissolution of the soluble polymer occurs when it is desired, but premature dissolution is suppressed by the ink.

In the case where the article consists of a polymer film, usually one or both sides of the film are coated with an insoluble paint. The polymer film should be thick enough to provide the desired mechanical strength, e.g. from 5 micrometers to 1 mm, preferably from 10 micrometers to 200 micrometers, e.g. 50 micrometers. The thickness of the colored layer ranges from about 1 micrometer to 7 micrometers, typically about 3 micrometers.

Articles of non-foil character may comprise a soluble polymer core, substantially or fully coated with paint. Such a product may resist exposure to water, but if the ink layer breaks, the water may dissolve the exposed core and the initially whole product may be disrupted from there.

In accordance with another aspect of the invention, there is provided such a method of forming a polymer article, comprising applying a liquid paint coating to a portion or all of the surface of an organic polymer article that is conventional, i.e. 20 ° C, water-soluble temperature. The coating formed is dried in a further step to form a barrier formed from a paint that does not dissolve at all or only very slowly in water at a given temperature.

If the material or article is a polymer film, the liquid ink may initially be applied to a clean roll of a conventional rotary printing press and subsequently transferred to a thin film of liquid ink in a conventional manner onto a roll of polymer film.

The ink may be used in any desired color or combination of colors to give the product an attractive external appearance. If desired, different inks can be used to achieve the desired effect.

Referring to all the advantages of the present invention and, as described in WO 92/01556, the rate at which the much more soluble polymer (first) dissolves can vary according to the choice of polymer and also the processing conditions. The dissolution time of the polymer depends on the ability of the polymer or material to resist dissolution and varies from the order of seconds to hours. The soluble polymer will generally have a dissolution rate such that when the polymer film with at least one exposed side is immersed in distilled water at 20 ° C, the film dissolves sufficiently and dissolves within 24 hours. It normally does not last longer than 8 hours and is often much shorter, in the case of a test sample of 50 microns thickness, it shall not exceed 10 seconds.

In the blend material described in WO 92/01556, the recommended weight ratio of the more soluble polymer to the less soluble 2: 1, preferably at least 3: 1, much more preferably at least 5: 1 and possibly above 10: 1, preferably up to even 100: 1, especially for coarse products.

On the other hand, the less soluble polymer covers the more soluble polymer with a uniform thickness of not more than 20 microns, preferably not more than 10 microns, more preferably not more than 5 microns. It can be only 2 microns thin, or even thinner.

In the blend polymer film, its total thickness can normally be 1 to 5 microns, preferably 10 to 200 microns.

Each polymer may be used in admixture with other conventional additives such as e.g. dyes and / or fillers, if necessary, in one or both layers.

The products may take various forms. So eg. the mixed film may consist of just two layers, each of the same polymer. In addition, the blended film may take the form of a sandwich when the more soluble polymer lies between the layers of the less soluble polymer. Of course, the layers of other materials may be present sequentially.

In the above-described processes, the first water-soluble (or only water-soluble) polymer is preferably the polyvinyl alcohol hydrolyzed in time. The second, relatively water-insoluble polymer, is completely hydrolyzed polyvinyl alcohol. The extrudable and blown compositions are preferably plasticized compositions of the respective polymers.

For extrusion, the first (water-soluble) polymer-based plasticized composition contains an emollient in an amount of from 1 to 60, preferably from 5 to 35, parts by weight or volume, preferably from 10 to 20 parts, most preferably 15 parts by weight. 100 parts polymer. It further comprises up to 30 parts, preferably from 0 to 15 parts, even more preferably from 1 to 15 parts (by weight or by volume), preferably from 3 to 15 parts, and more preferably 5 parts of water, based on 100 parts of polymer. Further, the subject composition comprises up to 5, typically from 0.01 to 5 parts (by weight or by volume), preferably from 0.01 to 3, more preferably 0.25 parts, of a S1O2 powdered flow promoting agent based on 100 parts. polymer. Such a composition is novel and itself constitutes another aspect of the present invention.

For extrusion, the plasticized second polymer-based composition comprises a plasticizer in an amount of from 1 to 80, preferably from 5 to 60, parts by weight or volume, preferably from 15 to 35 parts, more preferably 25 parts, based on 100 parts of polymer. It further comprises up to 30 parts, usually from 0 to 15 parts, more preferably from 1 to 15 parts (by weight or by volume), preferably from 3 to 15 parts, more preferably 5 parts, usually from 0.01 to 5 parts water, based on 100 parts polymer. Further, the present composition comprises up to 3 parts (by weight or by volume), preferably from 0.01 to 3, more preferably 0.25 parts, of a S102 powder type glidant based on 100 parts of polymer. Such a composition is also novel and constitutes a further aspect of the present invention.

As a plasticizer, it is generally possible to use any commercially available plasticizer for the polymer. For polyvinyl alcohol-based polymers, polyfunctional alcohols such as glycerol, glycol, alkanediol (e.g. ethanediol, propanediol, butanediol, pentanediol or hexanediol), other alkanetriols such as e.g. hexanetriol or trimethylolpropane), fatty acid monoglycerides or a mixture thereof.

The extrudable compositions described above are generally solids in granular form, as opposed to the aqueous compositions recommended for extrusion in WO 92/01556. It is particularly noteworthy that the compositions of the invention use significantly less water than comparable known compositions. However, in other molding processes, higher dosages of water may be required. Such considerations, however, fall within the competence of people skilled in the technology.

It is recommended that the ingredients as ingredients of the composition be mixed together at an elevated temperature (e.g., 110 ° C), but this is not a requirement. Low temperatures can also be used for mixing, but the mixing time will be prolonged.

The extrusion is carried out under pressure and preferably at elevated temperature. The proper pressure and processing temperature can be set by a skilled worker, based on the melting and degrading conditions of the polymer used.

Processing additives such as antifoams and lubricants may be used if necessary.

Such features of the conventional process, which are within the skill of the art, can be used to some extent in the novel method of the present invention and will not be discussed in more detail now.

However, the following, particularly novel, preferred features of the invention are mentioned:

firstly, it has been found that in the case of polyvinyl alcohol, an extrusion temperature (in the nozzle) in the range of 190 to 240 ° C (e.g. 215 ° C) gives the best results.

Further, each polymer composition is suitably conveyed to the die of a short extruder having a drip device to prevent blockage. The extruders should be arranged so as to avoid excessive shear forces on the compositions during their transfer by desirable pressure to the distribution channels and in a sufficiently short time so that there is no significant polymer degradation (about 4 minutes under normal extrusion conditions for PVA blends).

It has been found that such a requirement can suitably be achieved by using such an extruder for each mixture having two or more compression zones in the extrusion sleeve allowing the release of vapors between the zones, wherein the sleeve is under careful temperature control or a series of temperatures along its length. Downstream of the last compression zone, the composition enters the inlet channel of the nozzle, if necessary through a temperature controllable adapter to adjust the temperature of the mixture to the extrusion temperature.

In relation to other aspects of the present invention, there is therefore also provided an apparatus for delivering an extrudable plasticized organic polymer-based composition by means of an extrusion die through the molding process of a composite polymer material or article. Such a device consists of an extruder with two or more compression zones in the extrusion sleeve, with the possibility of exhausting vapors between some or all of the zones, a temperature control means where the sleeve can be maintained at a controlled temperature or a series of temperatures along its length.

The extrusion die may be in the form of a coextrusion die for receiving both polymers, or may include a die having separate slots for extruding each polymer separately, and a pressing device downstream of the extruder die to laminate the polymer layers after extrusion. In these cases, each polymer is conveyed by its own screw extruder as described above. However, the nozzle can also be in the solution as a simple nozzle for extruding only the water-soluble polymer for subsequent application.

The positions of the compression portions along the extruder housing are selected to suit the extruded composition. Preferably, the first compression zone is positioned sufficiently far into the housing such that the composition has received a significant impulse before entering the compression zone to facilitate dosing and to prevent blockage (further reducing the possibility of blocking in the compression zone and reducing shear stress of the mixture, compression of the composition). increases gradually towards the compression zone). Similarly, the last compression zone prior to the inlet of the mixture into the nozzle may be adjusted such that the compression of the composition gradually increases into the zone (at the same time reducing shear stress, preventing backflow of the mixture out of the vent hole in substantially zero compression zone immediately before the last compression zone). ).

The compression ratio, screw diameter and extrusion speed of the extruder are the parameters selected to suit the particularities of the polymer composition being processed. Thus, for example, a softened mixture based on insoluble PVA can be conveniently supplied at a compression ratio of from 1.1: 1 to 5.6: 1 (preferably

2.15: 1), while the soluble PVA-based composition can be conveniently supplied at a compression ratio of from 1.5: 1 to: 1 (preferably 3: 1). It is desirable to deliver the soft insoluble PVA based composition to the coextrusion die at a relatively high extrusion rate and a small screw diameter as compared to the soft solubilized PVA based composition. In particular, the softened insoluble PVA can be delivered at an extrusion rate of about 70 rpm using an 18 mm diameter screw, and a softened soluble PVA at an extrusion rate of 50 rpm through a 25 mm diameter screw.

As stated above, the temperature conditions along the housing are regulated. The temperature of each successive portion of the housing may increase, remain unchanged, or decrease towards the nozzle. It has been found that the plasticized insoluble PVA based blend is preferably extruded such that the temperature of each successive third of the casing toward the die increases, preferably at steps of 180 30 ° C, 230 30 ° C and 250 30 ° C; For the extrusion of the plasticized soluble PVA mixture, the temperature of each subsequent third does not substantially change, or only slightly decreases towards the die, suitably at steps of 203 30 ° C, 202 ° C and 199 30 ° C.

Industries can use them

Possible uses that can be envisaged for the layer 14 of articles prepared according to the present invention include irreversible packaging material and barrier layers in sanitary articles, such as e.g. diapers and fixed bedding. These products should, on the one hand, be capable of withstanding moisture; when using the films of the present invention, they can be discarded after use, even with their contents, in a toilet bowl to be unfolded. Everything can then be flushed to waste. The advantage in terms of comfort is evident, since PVA is biodegradable to harmless CO2 and water from the environmental point of view, nor is its toxic properties known and therefore does not present a risk from the point of view of chemical degradation.

Another field of application is in water-degradable containers, e.g. rigid oil containers. These are conveniently manufactured by blowing the first water-soluble polymer into containers into a conventional manner and applying an outer coating of a second, water-soluble polymer or water-insoluble printing ink (e.g. by spraying).

Explanation of the attached pictures

Embodiments of the invention will be described hereinafter by way of example, with reference to the accompanying drawings, in which;

fig fig fig fig fig fig shows a longitudinal cross-section of the coextrusion head assembly;

shows a plan view of the head assembly of FIG. 1;

shows (a) a plan view and (b) a longitudinal cross-section of the lower part of the housing block of the assembly of Fig. 1;

shows (a) a top view and (b) a front view of the first part of the mandrel assembly of Fig. 1;

4 is a side view of the mandrel portion of FIG. 4 (b);

shows (a) a bottom view and (b) a front view of the second mandrel portion (second portion of the mandrel assembly) of the assembly of Figure 1;

6 is a side view of the mandrel portion of FIG. 6 (b);

shows (a) a front elevation and (b) a longitudinal cross-section (with enlarged detail) of the upper portion of the housing block of the assembly of Fig. 1;

Fig. 9 shows a longitudinal cross-section of the head insert of the assembly of Fig. 1;

Figure 10 shows (a) a plan view and Figure 1;

Fig. 11 shows (a) a front view (b) of the ring of the assembly of Fig. 1;

Fig. 12 shows a semi-schematic vertical cross-section of the head assembly for coextrusion through a flat die;

Fig. 13 is a cross-sectional view of the head assembly of Fig. 12 taken along line AA in the direction of the arrows;

14 is a schematic view of a first coextrusion apparatus; FIG.

Fig. 15 is a schematic view of a second coextrusion (b) front elevation of the assembly outlet on the longitudinal cross-section of the clamping apparatus; Fig. 16 is a side elevational view of the screw apparatus of Figs. 14 or 15;

17 shows a cross-section of a film protected by a layer on one side; and Fig. 18 shows a cross-section of a film protected by a layer on both sides.

parts of extruder for color protection

DETAILED DESCRIPTION OF THE INVENTION

Detailed description

P ou ž. that. m a t e r i a y

In the following examples of the invention, both the soluble and insoluble layers were made of PVA. The type of PVA used was a mark) from Hoechst using Mowiol 26-88, which had a medium molecular weight

Mowiol (registered AG). The soluble layers were prepared by partially hydrolyzed PVA, having a weight of about 103,000, with a 88% (mole) degree of hydrolysis, the viscosity of which was measured to 4% aqueous solution, 26 mPa.s ² . a combination of Mowiol 56/98 and Mowiol 28/99, fully hydrolyzable PVAs having viscosity values and degrees of hydrolysis of substantially 16 as indicated above at their respective specification numbers, at a ratio of 50:50.

Example 1

The composition based on plasticized PVA type Howiol 26-88 had the following composition (parts per 100 parts by weight of polymer):

Howiol 26-88 ............ 100 glycerine (plasticizer) ... 15 distilled water .......... 5 powdered S1O2 .......... ... 0.25

S1O2 powder was used as a lubricant, in this case Powdered Silica R 972 from Aerosil.

All ingredients were pre-heated to a high-speed mixer (Baker Perkins 110 ° C) pre-heated to a Baker-Perkins Limited), which was homogenized at 600 rpm for 6 minutes while the material was allowed to float. equipment, where it was stirred for 15 minutes or until the material temperature dropped below 40 ° C.

In the mixing process, the glycerin-based plasticizer together with the silica lubricant encapsulates the Howiol granules, the distilled water being absorbed by the granules. The whole process is accompanied by an increase in temperature.

Example 2

The 50:50 softened PVA composition of Mowiol 56-98 and Mowiol 28-99 had the following composition (parts for

100 parts by weight of polymer):

Mowiol 56-88 ............ 50

Mowiol 28-99 ............ 50 glycerine (plasticizer) ... 25 water ................... 5 powder S1O2 ............. 0.25

All ingredients were initially metered into a high-speed Baker-Perkins mixer preheated to 110 ^e C. Homogenization was first at 600 rpm for 30 seconds and then at 1000-1200 rpm for about 15-17 minutes, with the material floated to the sides of the blender. The mixture was then poured into a cooling device, where it was stirred for 15 minutes, respectively. until the temperature of the material has dropped below 40 ° C.

The liquid ink used was a hydrocarbon-free alcoholic solution of the flexographic ink used for printing polyolefin films under the trade name ORION (manufactured by Coates Lorilleux Limited, Essex, England). Such inks are almost odorless and have low solvent retention so that they dry relatively quickly after application to the polymer surface. They have good adhesion to the surface, are frost-resistant and have acceptable antistatic and slip properties. If desired, the liquid ink may be mixed with other conventional additives, diluents, dyes or solvents.

K oe x_t rún a _hu b i.c a

Referring first to Figures 1 to 11 of the drawings, there is shown a coextrusion head assembly comprising a lower portion of the housing block 1 covered by an electrically heated housing (approx. 600 W; 240 V) 2; a first (outer) mandrel portion 3; a second (inner) mandrel portion 4 disposed within the hollow interior of the first mandrel 3; a top of the housing block 5; a nozzle insert 6; a pin 7 located in the nozzle insert 6; and an upper sleeve 8.

The metal housing block L has a cylindrical shape and is provided near its base by a pair of inlet channels?, 10 oriented at an angle of approximately 120 to each other. The upper part of the block is provided with six countersunk holes 11 for receiving screws 12 securing the upper block 5. to the lower block 1; a similar number of holes is provided for the lower part of the block 1 for receiving the screws 14, which secure the flange part 15 of the inner mandrel 4 in a given position.

Each of the inlet channels?, 1.0. has a shoulder piece 16, 1.7 .. fitted to connect the wider diameter of the screw extruder (discussed in more detail below with recommendations in Figs. 12 and 13) to the inlet ducts. The extension pieces are metal and are equipped with an insulating sheath 1.8, electrically heated, allowing temperature control. Preferably, the temperature maintained by the heated sheaths 2 and 18 will be substantially the same, with the extensions 16, 17 also functioning as temperature regulators of the incoming polymer compositions.

The first (outer) mandrel portion 3 generally has the shape of a cylinder adapted to fit snugly into the housing block 1, itself having a hollow central channel 19 through which the second (inner) mandrel 4 passes, as will be described in more detail below.

The outer mandrel 3 is metallic and has on its outer surface formed by a blunt-blades a polymer distribution channel 20 that starts relatively near the base of the mandrel, at a location adjacent to the casing inlet channel 9, and rises upwardly around the mandrel. no. clockwise and counterclockwise, narrowing upwards to a width until it ends on the opposite side of the mandrel.

In processing, the polymer composition entering the die through the inlet duct 9 encounters a relatively wide portion 21 of the guide duct 20 where it subsequently splits its flow so that it flows around the mandrel from both sides along the guide duct.

When more polymer enters the inlet channel, it is discharged from the distribution channel through the relatively smaller diameter of the upper mandrel portion 22. This top portion 22 of the mandrel, which is separated from the adjacent top portion 23 of the interior of the housing block 1, defines a first circular distribution 2.4 into which the polymer flows from channel 2.0 and the inlet channel 9 to distribute the polymer along the circumference of the mandrel 3.

The channel 20 significantly assists in achieving a uniform circumferential distribution of the polymer around the mandrel 3.

The mandrel 3 has a radially extending aperture 25 in its wall near its base to connect the second inlet channel 10 to the second (inner) mandrel 4, as will be described in more detail below. In addition, the lower part of the outer mandrel 3 is provided with six bolt holes 2.6 to secure the inner mandrel 4 by its base 15 in the assembly.

The second (inner) mandrel 4 also has a cylindrical shape, but smaller than the first mandrel 3, adapted to fit snugly into the hollow central channel 19 of the first mandrel. The second mandrel 4 also has a central duct 27, but serving to convey compressed air to the blowing stage, as will be described in more detail below.

The inner mandrel 4 has a substantially similar shape and function to the mandrel 3, having a polymer distribution channel 28 formed on the mandrel surface 4 that extends from the second inlet channel of the housing 10 and the mandrel opening 25, spilling around the periphery of the mandrel 4. to the second annular distribution 29 formed by the top portion 30 of the inner wall of the first mandrel 3 and the top portion 31 of the second mandrel also having a partially tapered diameter and is therefore positioned non-smoothly on the top portion 3.0 of the inner wall of the first mandrel. The guide channel 28 rises upwardly around the mandrel, twisting it around on both sides, narrowing upwards from the inlet channel 10 until it ends on the opposite side of the mandrel 4, analogously to the guide channel 20 of the mandrel 3.

The lower base 15 of the inner mandrel 4 is provided with six radially extending in the outer assembly through screw holes 3.1.

14 securing the inner mandrel 4 by means of its base 15 in the housing assembly 1. The lower base 15 is also provided with six radially inwardly extending bolt holes 32 to secure the inner mandrel 4 to the outer mandrel 3.

At the upper ends of each of the pipes 24, 2? There are throttling elements 33, 34 which regulate the thickness and uniformity of each polymeric film before the two polymeric films meet and join together to form the desired bilayer.

In the case of the first channel 24, the throttle element 33 is a convex portion 3.5 which is located on the inner cylindrical portion of the upper block of the assembly portion 5. The block 5 has an inner wall 36 which tapers inwardly upwardly to guide the extruded polymer so that it passes through the throttle element 33 downstream to meet the second polymer coming from the second manifold 29 through the throttle element 34.

The block 5 is fastened to the top of the housing 1 through six holes 37. Six small screw holes 38 ensuring a tight connection of the sleeve 8 to the block 5 is also located at the upper edge of the block 5, as will be described in more detail below.

The block 5 is also provided with four side openings 39a extending through its upper portion for the bolts 39b ensuring a tight connection of the sleeve 6 in the assembly to the hollow interior of the block 5, as will be described in more detail below.

The nozzle sleeve 6 has a hollow cylindrical structure and has an inner surface extending upwardly forming a chamber 40 hiding the pin 7. The pin 7 is hollow so that a hollow screw with a nut (not shown) can be passed through the pin to the enlarged upper part. main channel .2.7. of the inner mandrel 4 and securing the pin in the assembly. The central duct 27 and the central duct of the hollow screw together provide a passage through the center of the head assembly, allowing compressed air to pass through the nozzle. The pin 7 has an upwardly extending outer surface which guides the composite polymer film from the nozzle housing through the outlet aperture 41 to the blow region above the assembly.

The lower portion of the pin 7 is provided with an annular protrusion 42 forming the aforementioned throttle element 3.4 in the second conduit 2.9 when the protrusion is in a position near the upper portion 30 of the inner wall of the first mandrel 3.

The nozzle sleeve 6 is fixed to the top of the block 5 by an upper clamping ring 8 extending beyond both the upper block 5 and the flange portion 43 of the sleeve 6 by means of screws connecting the upper block 5 through the six holes 4.4 in the clamping ring 8 (FIG. b only one such aperture is shown for illustration). The upper block 5 is suitably covered by an electrically heated jacket 45.

Referring now to Figures 12 and 13, a double-slot coextrusion head assembly having two housing blocks 50a, 50b comprising conventional heating means (not shown) is shown; an upper slot nozzle having associated dosing and regulating means as described in more detail below; a lower slot nozzle having similarly connected dosing and regulating means.

Each slot nozzle 51, 52 is defined as a respective top 53 and bottom 54 movable edge separated from the rigidly fixed two-sided edge 55. each movable edge may vary the width of the respective slot in the direction from and to the fixed edge 55 via conventional adjusting screws 56. 57th

As shown in more detail in Fig. 13 (which is a schematic front view of a conduit suitable for passing the extrudable composition through the upper nozzle 51 - the lower nozzle 52 has the same solution), the extruded composition fed initially into the housing through the inlet channel 58 is further expanded into the distribution channel. 5.9, which leads the composition later through the exterior to the mouth of the elongated and relatively narrow groove conduit that forms the outlet of the distribution channel.

The guide channel 59 tapers inwardly in diameter and rotates a little forwards (in the direction of flow of the extruded composition) towards the edges (the dotted ellipses in Figure 13 represent changes in the guide channel profile) and these means expand the composition from one side to the other. formed in the housing blocks 50a, 50b. Referring to Figure 13, the upstream edge of the conduit has the shape of an arc as shown by line 61, so that a composition that has already passed transversely out through the distributor channel must pass a smaller distance through the conduit 60 before leaving the conduit to the pre-access zone 62. wherein the adjusting screw 63 (controlled by means 64) can be narrowed, if desired, to narrow the width of the zone to control the flow of the composition.

The dotted straight lines at bia 60 and the pre-entry zone of FIG. 13 represent the width of the screed62 (as shown, the width is constant and slightly narrower than the distribution channel, but wider than the end outlet a 54, 5.5).

of nozzle on edges 53, 54

From the pre-access zone 62, the composition flows countercurrently to the mouth of each of the die slits with edges 53, 54 and 5.4, 55 and then out through the die, thereby forming coextrusion in the form of laminated coextruded films processed conventionally by rollers, slicers and withdrawal system.

K oe x tr.ú.z n _e _._ from ar. ANAGEMENT

Referring now to Figures 14 and 15, the coextrusion devices are shown schematically, consisting mainly of a head assembly 70, with the solution of Figures 1 to 11, and a head assembly 7.1, with the solution of Figures 12 and 13 and described above.

The first inlet channel of the head assembly 70 is fed with the above-described softened soluble polyvinyl alcohol polymeric copolymer via the first extension piece 16 by a medium compression screw extruder 72 with a 25 mm casing diameter positioned between the first heated container 73 and the extension piece 16.

The second inlet channel of the head assembly 70 is fed with the previously described softened insoluble polyvinyl alcohol based polymer copolymer via the second extension piece 17 by means of a low compression screw extruder

7.4 with a housing diameter of 18 mm positioned between the second heated container 75 and the adapter piece 1.7.

The upper inlet channel of the head assembly 71 is fed with the above-described softened soluble polyvinyl alcohol polymer copolymer via the first extension piece 80 by means of a medium compression die extruder 7.2 having a 25 mm casing diameter positioned between the first heated container 73 and the extension piece 8.0.

The lower inlet channel of the head assembly 71 is fed with the above-described softened insoluble polyvinyl alcohol polymer copolymer via a second extension piece 81 via a low compression screw extruder 74 with a housing diameter of 18 mm positioned between the second heated container 75 and the extension piece 81.

according to Betol having an L / 0 and a compression ratio of 3: 1. zones 76, 77

As shown in more detail in FIG. 16, the screw extruder 72 was represented by a short 25: 1 ratio screw (screw length / screw diameter). The screw itself had two compression sections separated by a zone 78 in which the polymer mixture was not compressed and is the outlet 7 located? allows escape of vapors. The screw operates at a speed of 53-55 rpm.

The screw extruder 74 was generally similar in construction to the screw 72, although it had an L / D ratio of 18: 1 and a compression ratio of 2.15: 1 and a rotation speed of 71.4 rpm.

In the blow molding of FIG. 14, there were a pair of pressure rollers 83. mounted at a distance of about 0.75-1 m vertically above the nozzle, with withdrawal of the produced foil to the collection point (not shown). In the case of extrusion through the flat die shown in FIG. 15, the extruded film is discharged by a conventional extractor, rollers and slicers for finishing (not shown).

The threads of the metering screw continue along the entire length of the extruder, although for the sake of simplicity, only the first and last threads are shown in FIG.

Coetrusion process

The Mowiol-based polymer compositions were prepared as described above and subsequently discharged into the respective hoppers 90, 9.1 of the container 73, 75 of the extruder as granules. A drop feeder is used here to prevent clogging of the hopper mouth.

The mixture is introduced by the first part of the screw into the region 92 and passes into the housing of the extruder. In this region, the sheath temperature is maintained at a level of 203 30 ° C in the case of a soluble polymer and 180 30 ° C in the case of a insoluble polymer.

from the extruder, the base begins to taper towards the housing wall in the housing wall in this region

At a short distance, the diameter of the screw is conical (region 93) and then remains parallel to the distance equal to the length of the constriction.

(region 94) the mixture is compressed. The temperature of the sheath is maintained at 202-30 ° C for the soluble polymer and 230 ° C for the insoluble polymer.

Immediately thereafter, the thread diameter of the screw core narrows significantly, thereby releasing compression (region 95). The vapors exit through the opening 79 in the housing.

The compression is then repeated again in the extruder region 96 before the polymer composition passes into the extension time 24 and into the die. In this region (region 96), the sheath temperature is maintained at 199 30 ° C for the soluble polymer and 250 30 ° C for the insoluble polymer.

The temperature control is recorded by means of conventional insulation of the electric heating line.

The nozzles 7.0, 7.1 are each tempered to 214 ° C, the heated PVA composition is then fed into them by the appropriate screws in a ratio of e.g. 5: 1 (soluble: insoluble). In the case of blow molding (Fig. 14), warm air is blown while the foil is extruded. The blown sleeve, coated on a layer of insoluble PVA (is the outer surface - depending on which inlet channel of the nozzle is supplied), can be shaped above the nozzle. Cooling air is blown onto the sleeve surface above the nozzle in a conventional manner.

The blown air quickly dries the deflated sleeve to a non-sticky condition so that it can be flattened between the two pressure rollers 83 and folded to be subsequently cut to form a single-thickness film.

aperture in the middle of the nozzle 70. its inner surface thin optimally if it is located on which polymer it is

Referring in particular to FIG. 17, there is shown a pliable polymeric film consisting of a base layer 101 based on partially hydrolyzed (soluble) PVA, carrying on its surface a relatively thin insoluble layer 10.2 formed after drying of the previously mentioned ORION ink. Fig. 18 shows a modification of the film of Fig. 17, wherein the ink coating 1.0.2 is applied from both sides of the backing layer 101. In both cases, the coating 102 is applied as a liquid by conventional printing methods using ink followed by air drying.

The ink coating is applicable to all types of polymer products, but is particularly useful in thin-walled products or films. Then, when the shelf life of the product is complete, simply tearing or otherwise damaging the ink-based protective coating will lead to the dissolution of the polymer by water and its subsequent degradation by the natural action of microorganisms, and a protective coating of ink substantially less than the polymer will be dispersed by the natural during the polymer decomposition, since the ink itself does not have the necessary natural mechanical strength.

Claims (37)

A process for preparing a composite polymer article or polymer material comprising a first layer of an organic polymer that is water-soluble at a given temperature and a second layer of an organic polymer to a first adjacent polymer that is substantially less soluble in water at a given temperature than the first a polymer, optionally insoluble, characterized in that it comprises blowing the film or coextrusion through a flat die, processes in which the polymers are extruded in the form of a film through a narrow die die slot in such a way that the polymers leave the die as a composite material comprising polymer layers; or consists of an extrusion-lamination process in which the polymers are extruded from the extrusion die as separate polymeric films and are subsequently bonded together between the bonding means under the effect of temperature and compression pressure such that the films are laminated together to form a composite polymeric material comprising layers of polymers; or consists of a forming and deposition process wherein the first polymeric film is extruded or blow molded and the second polymeric film is applied as a film. A blow molding method of a composite polymer article or material according to claim 1, wherein the blow head of the extrusion machine comprises a first inlet feed of one of the polymers under pressure; a second inlet of another polymer inlet under pressure; a composite mandrel wherein the first portion of the mandrel assembly is hollow along its entire length so as to encircle the second portion of the mandrel assembly and the entire assembly is such that the first annular channel is defined around the outer periphery of the first portion of the mandrel assembly to distribute one of said organic polymers along the outer and a second annular channel is defined around the outer periphery of the second portion of the mandrel assembly to distribute the second of said organic polymers along the outer surface of the second mandrel assembly27, the arrangement further comprising a guide channel connected to one or each of the channels on the second mandrel assembly. distributing the polymer from a respective lead to a respective channel around substantially the entire outer periphery of the respective portion of the mandrel assembly. Method according to claim 2, characterized in that the distributor channel is connected to each of the nozzle channels. Method according to claim 2 or 3, characterized in that each distributor channel is provided with two polymer paths entering through the inlet channels; namely, the first path distributes the polymer in one direction around the respective mandrel of the extruder head and the second path distributes the polymer in the second direction around the mandrel. A method according to any one of claims 2 to 4, characterized in that each distribution channel is formed in the mandrel surface. 6. The method of claim S and c i sa by that the width of each switchboard channel from the inlet direction inwardly narrows. 7. Method of preparation of composite polymer article or by extruding the film by coextrusion through a flat die or by extruding two separate films through a flat die followed by a pressure lamination according to claim 1, characterized in that the die or die comprises a first inlet of one of the polymers under pressure; and a second inlet of the second pressurized polymer, and respective elongated slits in the die or die through which each film is extruded. A method according to claim 7, characterized in that at least one of the inlets supplies an inlet channel, which then extends into a distribution channel extending the polymer from one side to the other side of the slot opening of the nozzle. A method of preparing a composite article or material by extrusion of separate films followed by a pressure lamination according to any one of the preceding claims, characterized in that the pressure lamination is performed between two pressure rollers. A method of preparing a composite polymer article or material by molding a first polymer layer by extrusion or blow molding followed by applying a second polymer layer in the form of a coating according to claim 1, wherein the coating is formed by spraying. A method for preparing a composite polymer article or material by modifying the extrusion or blow molding of a first polymeric layer followed by deposition according to claim 1, wherein the second polymer in the form of a deposit is replaced by a dry residue of liquid ink which dissolves more slowly at a given temperature. as the first polymer, respectively. does not dissolve at all. 12. The method of claim 11, wherein the ink is a liquid alcoholic solution of the flexographic ink free of hydrocarbons. Method according to any one of the preceding claims, characterized in that the first polymer is extruded from a plasticized mixture comprising 1 to 60 parts of plasticizer per 100 parts of polymer; up to 30 parts water per 100 parts polymer; and up to 5 parts glidant per 100 parts polymer. Method according to any one of the preceding claims, except 11 and 12, characterized in that the second polymer is extruded from a plasticized mixture comprising L to 80 parts of plasticizer per 100 parts of polymer; up to 30 parts water per 100 parts polymer; and up to 5 parts glidant per 100 parts polymer. The method according to any one of the preceding claims, wherein the first, water-soluble polymer is partially hydrolyzed polyvinyl alcohol, and the second, almost water-insoluble polymer (if present) is fully hydrolyzed polyvinyl alcohol. Method according to any one of the preceding claims, characterized in that the polymer blend or each of the polymer blends is conveyed to the nozzle or nozzles by means of a screw extruder having two or more compression zones in the extruder sleeve which allow the vapor to be released between the zones and the sleeve. it is maintained at a controllable temperature or series of temperatures along its length. 17. A polymer product or polymeric material consisting of an organic polymer which is soluble in water at a given temperature, characterized in that the surface of the product or material is completely or partially covered with an ink which dissolves only very slowly in water at a given temperature. or does not dissolve at all, forming a protective, water resistant coating. The article or material of claim 17, wherein said temperature is room temperature (about 20 ° C). The article or material of claim 17 or 18, wherein the ink deposit is extended to all those portions of the surface for which it is expected or expected to be exposed to water during normal use. The article or material of any one of claims 17 to 19, wherein the organic polymer is partially hydrolyzed polyvinyl alcohol. The article or material of any of the preceding claims, wherein the ink jet is a dried residue of hydrocarbons devoid of a liquid alcoholic solution of the flexographic printing ink. A method for forming a polymer article or material according to claim 17, wherein a coating of liquid ink is applied to all or part of the organic polymer surface, and is subsequently dried until a protective, water-resistant ink coating is formed which it dissolves much more slowly in water than the polymer or does not dissolve at all at a given temperature. Method according to claim 22, characterized in that the liquid ink is applied first to the empty cylinder of a conventional film printing press and subsequently the thin film of liquid ink is transferred to the organic polymer film. 24. A head assembly for coextruding a composite polymer article or material comprising first and second layers of organic polymer adjacent to each other, comprising: an elongated housing with a first inlet for the inlet of one of the polymers under pressure; a second inlet to the inlet of another polymer under pressure and an outlet downstream of the inlets to the outlet of the composite material; and a composite mandrel assembly within the housing, wherein the first mandrel assembly portion is hollow along its entire length such that it surrounds the second mandrel assembly portion and the entire assembly arrangement is such that the first annular channel is defined around the outer periphery of the first mandrel assembly portion for distributing said one organic polymers along the outer surface of the first mandrel assembly member toward the outlet opening of the housing, and a second annular channel extending around the outer periphery of the second portion of the mandrel assembly to distribute a second said organic polymer along the outer surface of the second mandrel assembly member toward the outlet opening of the first and the second manifold is terminated together in such a way that the two polymers are extruded from the housing outlet as a composite polymer material comprising polymer layers; the arrangement further comprising a guide channel connected to one or each of the manifold channels and preferably having a relatively wider width than the respective polymer manifold channel from the respective housing inlet to the respective channel around substantially the entire circumference of the respective portion of the mandrel assembly. 25. A head assembly for co-extruding a composite polymer article or material comprising first and second layers of organic polymer adjacent to each other, comprising: a housing with a first inlet for the inlet of one of the polymers under pressure; a second inlet to the inlet of another polymer under pressure and an outlet downstream of the inlets to the outlet of the composite polymer material; head means defining a first elongate slot opening and a first distributor channel connecting the first inlet to said first slot opening, the distributor channel extending towards the slot opening and positioned to extend the polymer from one side to the other of the slot opening nozzle; head formulations defining a second elongate slot opening and a second distributor channel connecting the second inlet to said second slot opening, the distributor channel extending towards the slot opening and formed to extend the polymer from one side to the other of the slot opening nozzle; the first and second apertures are terminated together in such a manner that the two polymers exit together from the housing outlet as a composite material comprising two polymer layers. 26. Apparatus for supplying an extrudable softened composition based on an organic polymer by means of an extrusion die by a process of forming a composite polymer material or article, consisting of an extruder with two or more compression zones in an extrusion sleeve and capable of aspiration between some or all of the zones; maintained at a controllable temperature or series of temperatures along its length. 27. The apparatus of claim 26, wherein the die is a coextrusion die of claim 24 or 25. Apparatus according to claim 26 or 27, characterized in that the screw extruder is adapted to deliver the mixture at a compression ratio of 1.1: 1 to 5.6: 1. Apparatus according to claim 26 or 27, characterized in that the screw extruder is adapted to deliver the mixture at a compression ratio of 1.5: 1 to 6: 1. Device according to any one of claims 26 to 29, characterized in that the temperature control means are arranged such that the temperature of each subsequent third of the housing increases towards the nozzle. Device according to any one of claims 26 to 29, characterized in that the temperature control means are positioned such that the temperature of each subsequent third of the housing remains substantially unchanged or slightly decreases towards the nozzle. 32. A plasticized composition based on partially hydrolyzed polyvinyl alcohol comprising 1 to 60 parts of plasticizer per 100 parts of polymer; up to 30 parts water per 100 parts polymer; and up to 5 parts glidant per 100 parts polymer. 33. A fully hydrolyzed polyvinyl alcohol base composition comprising 1 to 80 parts of plasticizer per 100 parts of polymer; up to 30 parts water per 100 parts polymer; and up to 5 parts glidant per 100 parts polymer. An article or material produced by the process of any one of claims 1 to 16, 22 and 23. The article or material of claim 27 in the form of a film. The article or material of claim 27 in the form of a container A sanitary product disposable by disposal in a toilet, wherein substantially all of the plastic parts are made of a film according to claim 35, wherein the water-soluble layer is furthest from the environment in normal use while avoiding contact with water until disposal. A container for non-aqueous materials (e.g., oil or gasoline), substantially entirely made of the polymeric material of claim 36, wherein the water-soluble layer acts as a contact in contact with the materials in normal use, avoiding contact with water until disposal requirements. 39. Sanitary products, disposable by disposal in the toilet, comprising an absorbent part and a plastic insulating backing, where after flushing into the toilet all plastic parts are completely degradable by water. 40. Degradable container for oil or petrol, which degrades completely only after pouring water into the container.