Method for the Production of a Layer for Coating the Plastic Inner Surface of a Receptacle, and Receptacle Obtained by a Method of Said Type

Abstract

The invention relates to a method for producing a barrier layer (13, 9) for coating the inner surface (12, 17) of a receptacle (10, 6) which is made at least in part of plastic and is used for holding products that are biocompatible for humans and/or animals; in said method, a solution is formed that contains at least one solvent, water, at least one organo-functional molecular precursor, and an acid as a catalyst, the complexed solution, which is undergoing hydrolysis and condensation, is applied to at least one portion of the inner surface of the receptacle, the applied solution is dried at a specific drying temperature below 100 C., and the receptacle is conveyed away and stored before being baked. The acid used is citric acid.

Claims

1. A process for the manufacture of a barrier layer (13, 19) for coating the internal face (12, 17) of a receptacle (10, 16), at least partly made of plastic, suitable for containing products biocompatible with man and/or animals, in which: a solution containing at least one solvent, water, at least one organofunctional molecular precursor and citric acid, as catalyst, is formed (5), the solution thus complexed is applied (6) to at least a part of the internal face of the receptacle, the solution being in the course of hydrolysis and condensation, and the solution thus applied is dried (7) at a predetermined drying temperature of less than 100 C. before evacuation and storage.

2. The process as claimed in claim 1, characterized in that the predetermined drying temperature is between 70 C. and 95 C.

3. The process as claimed in claim 1, characterized in that the solution contains at least two organofunctional molecular precursors.

4. The process as claimed in claim 1, characterized in that the organofunctional molecular precursor is taken from octadecyltrimethoxysilane, the family of the dipodal silanes and the family of the aminopropyl silanes.

5. The process as claimed in claim 1, characterized in that the receptacle is entirely made of plastic.

6. The process as claimed in claim 1, characterized in that the receptacle is made of glass, the internal face of which is intended to be covered with a layer of plastic.

7. The process as claimed in claim 1, characterized in that the solvent comprises butoxyethanol and/or ethanol.

8. The process as claimed in claim 1, characterized in that the solution also comprises at least one pigment and/or one dye.

9. The process as claimed in claim 8, characterized in that the pigment is taken from metal oxides comprising cobalt and titanium, metal oxides comprising copper and chromium, or photochromic pigments and/or the dyes taken from the families of compounds comprising Pyrisma and/or Iriodin, which are registered trademarks of Merck, quinacridone, phthalocyanine, quinophthalone and the compounds formed of a layer of aluminum and/or its oxides, said layer being itself coated with a layer of silicon oxide.

10. The process as claimed in claim 1, characterized in that, per 100 units by volume of final solution, the proportions are from 80 to 98 units of solvents, including, out of 100 units of solvents, at least 90 parts of ethanol, from 1 to 19 units of organofunctional precursors, from 0.02 to 0.15 unit of acid and from 0.1 to 1 unit, with or without addition of 1.5 to 6 grams of pigments and/or dye and/or functional additives per 100 ml of final solution.

11. A receptacle (10, 16) comprising an internal surface (12, 17) made of plastic and suitable for containing products biocompatible with man and/or animals, characterized in that said surface (12, 17) is covered, over at least a part, with a solidified coating layer (13, 19) obtained from a solution comprising at least one solvent, water, at least one organofunctional molecular precursor and citric acid, as catalyst, said coating layer forming a hybrid organoinorganic matrix arranged in order to produce a physicochemical barrier.

12. The receptacle as claimed in claim 11, characterized in that the coating comprises pigments and/or dyes.

13. The receptacle as claimed in claim 10, characterized in that it is formed of a tube which can be folded over and/or closed at its end and/or by a bag made of plastic or coated with an internal layer made of plastic.

Description

[0091] A better understanding of the invention will be obtained on reading the description which follows of embodiments described below as nonlimiting examples and with reference to the FIGS. which accompany it, in which:

[0092] FIG. 1 is a flow diagram showing the stages of a process for the manufacture of a coating layer according to one embodiment of the invention.

[0093] FIG. 2 shows, in exploded partial view, a receptacle according to one embodiment of the invention.

[0094] FIG. 3 diagrammatically shows, in section, an embodiment of a device implementing the process according to one embodiment of the invention applied to a bottle.

[0095] FIG. 1 gives the flow diagram of the main stages of the process according to the embodiment of the invention more particularly described here.

[0096] The process comprises a preliminary stage (not represented) of supplying with at least one receptacle or bottle made of plastic to be treated, for example HDPE (high-density polyethylene).

[0097] The receptacle is formed of a material which, suitably treated, will make it possible to contain products biocompatible with man and/or animals, that is to say compatible with an ingestion and/or an application to the human or animal body (medicaments, cosmetic products, and the like).

[0098] The process comprises, subsequently or not (test 1), a stage 2 of passivation of the internal face of the receptacle.

[0099] It should be remembered that passivation is understood to mean an extraction, prior to the use of the bottle, of the elements liable to depart from the internal wall of the bottle during contact with liquid or pasty contents which will be subsequently stored therein.

[0100] The extraction has to be sufficient for the measurements by weight of these elements to be below a predetermined threshold set by the standards in force.

[0101] Each of the passivation embodiments (stage 2) can be repeated several times (test 3-4), for example twice.

[0102] This passivation stage further reduces the amount of ions which risk being released subsequently into the contents of the receptacle, in particular when the coating layer does not cover all or most of the internal surface of the receptacle. It also advantageously prepares the internal face for the adhesion of the coating layer.

[0103] The passivation stage can also be carried out by a treatment known to a person skilled in the art under the atmospheric-pressure plasma name.

[0104] After this stage, a stage 5 of preparation and formation of the solution according to the embodiment of the invention more particularly described here is carried out, if this has not been carried out beforehand in parallel or otherwise, for example in a separate place and in a period of time before its application which can reach several hours.

[0105] The preparation stage comprises a first stage of mixing the precursor(s) with at least one solvent and with aqueous acid solution (stage 6). The mixture is produced, for example, in a vat with stirrer at a predetermined temperature and for a predetermined time, for example at a temperature of between 10 C. and 50 C., for example of between 15 C. and 35 C., for example 24 C. (ambient temperature), and mixed for a period of time of, for example, between 10 min and 1 h, for example of between 25 min and 45 min, for example 30 min.

[0106] In the more particularly preferred embodiment described here, the acid is citric acid.

[0107] It is also here that the pigment is added, and then the mixture is subjected to ultrasound alternating with mixing (stage 7).

[0108] The mixing is thus carried out in an aqueous liquid, making possible hydrolysis of the precursor, and fluidifies the result obtained, making possible easy application.

[0109] The solution prepared in the end has a low concentration of citric acid, i.e. less than 0.01 mol/l.

[0110] The solution or sol is subsequently applied (stage 8) to the wall or walls made of plastic of the receptacle, as will be described, for example and more specifically, with reference to the device of FIG. 3.

[0111] Finally, a drying stage 9 is provided, the catalysis and the drying resulting in a gelling being obtained, which gelling gives a solid layer.

[0112] In the embodiments more particularly described here, the solvent is ethanol.

[0113] In a first embodiment, the molecular precursor is 3-glycidoxypropyltrimethoxysilane. The acid used is then nitric acid.

[0114] The sol-gel thus obtained has a viscosity which makes it more difficult to apply in receptacles of complex shapes but makes possible better control of the covering, for example a viscosity of less than 1 Pa.s at ambient temperature (approximately 24 C.).

[0115] In a second embodiment, the molecular precursor is octadecyltrimethoxysilane.

[0116] In a third embodiment, the precursor is (3-aminopropyl)triethoxysilane and the catalyst is citric acid.

[0117] Two examples which have given excellent results with the invention have been reproduced below.

[0118] Example 1: Hybrid organosilane layer on a pillbox made of plastic with pigments.

[0119] 10 ml of EtOH (ethanol), 0.2 g of quinacridone pigments, 2 ml of octadecyltrimethoxysilane (or octa), 400 l of dipodal BTSE, and 100 l of citric acid (4 g+20 ml) are mixed for 4 h; gradual drying 80 C. by stationary phases of 5 C./min for 1 h.

[0120] More specifically, 10 ml of EtOH and 0.2 g of pigments are introduced into a flask; two subjections to ultrasound are subsequently carried out and then the 2 ml of octadecyl, the 400 l of dipodal precursor and then the 100 l of acid (4 g+20 ml) are introduced; then, after again subjecting to ultrasound, stirring is allowed to take place for 4 h, the preparation is then applied to the pillbox and drying is carried out at 80 C., the temperature being raised at a rate of 5 C./min, for 1 h.

[0121] Example 2: In a glass bottle, a layer for attachment to the glass, forming a layer made of plastic, is created from powder on the inside by deposition of the plastic in a way known per se, for example by deposition of thermoplastic powder.

[0122] In an advantageous embodiment, the coating is also put on the glass in order to make possible a better attachment of the plastic layer inside the bottle, taking advantage of the qualities of adhesion to plastic of the sol-gel of the invention.

[0123] First, for 5 h, 30 ml of EtOH, 600 l of (3-aminopropyl)triethoxysilane and 60 l of acid (4 g+20 ml) are mixed, before drying at 80 C., 5 C./min-1 h.

[0124] More specifically, 30 ml of EtOH, 600 l of amino and 60 l of acid (4 g of citric acid dissolved in 20 ml of water) are introduced into a flask and stirring is allowed to take place for 4 h.

[0125] The coating is applied to the bottle and the final step is a drying at 80 C., rising by 5 C./min, for 1 h.

[0126] Example 3:

[0127] Application of a coating layer containing an antibacterial function in a flexible tube open at one end and closed by the future screw dispenser at the other.

[0128] The mixture is prepared in the following way:

[0129] 10 ml of ethanol, 2 ml of octadecyltrimethoxysilane precursor and 400 microliters of dipodal silane BTSE are introduced into a flask.

[0130] Stirring is carried out for 5 minutes, 100 microliters of citric acid (contributing water and acid) are then introduced, followed, 1 minute later, by 0.5 g of silver-based colloidal agent.

[0131] Mixing is carried out for 4 h after subjecting to ultrasound more than once. The product is subsequently sprayed into the tube and dried at 80 C. for 1 h. The tube can subsequently be filled and the open end closed by plastic welding.

[0132] With the invention, the solvent is instead ethanol, because it evaporates at a lower boiling point. Likewise, one of the advantageous cases which can be employed with the invention is the use of the layer with (3-aminopropyl)triethoxysilane on glass in order to act as underlayer for attachment of thermoplastic dusting inside the bottle made of glass (glass itself not compatible with the fragrance in this case), this being by virtue of the amine functional group.

[0133] This coating makes it possible not to treat the glass layer in a polluting fashion by virtue of this thermoplastic dusting.

[0134] With the invention, it is possible to attach a coating even in the presence of fragrances or other alcohol-comprising product, which is an amazing performance in itself, revealed by an aging test in the presence of fragrances at 50 C. for at least eight weeks without degradation of the layer and of the product.

[0135] In the case of the underlayer, it makes possible the attachment of the thermoplastic product 1): at T 0 during the deposition, 2): after aging at 40 C. for eight weeks in a climate-controlled (vacuum) chamber.

[0136] By way of example, the results of appearance, of hold toward rubbing of the coating and of hold toward eau de cologne (after one month in contact with the latter at 45 C.) with regard to two examples 4 and 5 have been represented below (table).

[0137] Examples 4 and 5:

[0138] Example 4 is a conventional sol-gel coating based on tetraethoxysilane with 10 ml of ethanol, 4 ml of TEOS, 4 ml of citric acid (4 g+20 ml) and 0.2 g of pigment, applied to a plastic pillbox made of HDPE and dried at 80 C. for 1 hour. The initial attachment and the appearance are correct, as is the static hold toward eau de cologne; on the other hand, the coating is not very resistant to rubbing.

[0139] Method of preparation: 10 ml of EtOH, 0.2 g of quinacridone rose pigment, 4 ml of TEOS and 4 ml of acid (4 g+20 ml) are introduced into a flask.

[0140] Example 5 according to the invention is a coating on the same pillbox made of HDPE which comprises 10 ml of ethanol, 2 ml of octadecyltrimethoxysilane, 0.4 ml of BTSE and 100 microliters of citric acid. After application, the coating is dried at 80 C. for 1 h and gives good results.

[0141] Method of preparation: 10 ml of EtOH and 0.2 g of pigment are introduced into a flask, the mixture is subjected to ultrasound twice and then 2 ml of octadecyltrimethoxysilane, 400 l of BTSE and 100 l of acid (4 g+20 ml) are introduced into the flask, and stirring is allowed to take place for 4 h.

[0142] In example 6, a conventional hybrid solution was tested, which solution in particular did not attach to the surface, from the contact with the eau de cologne.

TABLE-US-00001 TABLE Appearance Rubbing hold, coating Eau de cologne hold Example 4 + + Example 5 ++ +++ +++ Example 6

[0143] An excellent attaching is thus found with the examples commonly within the scope of the invention, while retaining a satisfactory appearance and a good hold over time toward eau de cologne, better than with the prior art (example 6).

[0144] FIG. 2 shows a bottle 10 made of plastic intended to receive a product biocompatible with man, for example of cylindrical shape, partially in section.

[0145] It comprises a wall 11 provided with an internal face 12 liable to be covered with a coating 13 (as dot-and-dash line) according to the invention, for example over the entire height of these walls from the bottom or base 14 of the receptacle to the bottleneck 15, forming an opening O.

[0146] The opening O of the bottleneck 15 comprises a neck C with a smaller diameter than that of the bottle 10.

[0147] An embodiment of a device which makes it possible to implement the invention will now be described without implied limitation, with reference to FIG. 3.

[0148] Subsequently, the same reference numbers can be used to denote identical or similar elements.

[0149] More specifically, FIG. 3 shows a device 22 for coating 19 at least a portion of the internal surface 17 of a receptacle 16, in this instance, for example, forming a cylindrical vial or bottle made of plastic extended with a cylindrical neck C, around an axis O.sub.z. It thus comprises, at one of its ends (top end), an opening O as a bottleneck, the opening of the bottleneck comprising the neck C with a smaller diameter than that of the receptacle or bottle 16.

[0150] The receptacle thus substantially forms a chamber.

[0151] The device comprises a support S of the receptacle, for example comprising a retention clamp M in the shape of a dish or of a U, the branches L of which grip the base, that is to say the bottom, of the receptacle fixed via lateral screws (not represented).

[0152] Means 23 for rotating the receptacle around its axis O.sub.z at a predetermined speed V are provided which are known per se. The speed V can be unchanging or variable and regulated. More specifically, the means comprise, for example, a rotating rod for driving the support which extends along the axis O.sub.z and a motor for driving in a way known per se.

[0153] Means 24 for insertion/extraction (arrow 25) of a spraying tool or nozzle 26 inside the receptacle are mounted on a frame B, as dot-and-dash lines in the FIG., on the side of the bottleneck of the receptacle 16.

[0154] The nozzle 26 comprises a longitudinal shaft or tube 27 connected, at its end 28, to the insertion means 24 comprising an actuator 23 for longitudinal displacement, such as a jack.

[0155] The action of the jack, which is integral with the nozzle 26, relocates the latter from an initial position external to the receptacle 13 to a position of operation internal to the receptacle along the axis O.sub.z.

[0156] It thus makes possible a gradual descent, continuous or stepwise, of the tool for application of the coating solution (gel in formation) to the internal surface of the receptacle.

[0157] The nozzle brings about vaporization 30 along a predetermined solid angle for dispersion which depends on the ejection rate and pressure controlled in a way known per se.

[0158] The tube is connected, at its opposite end, to a system 31 for dispensing a liquid coating solution to be sprayed comprising means 32 for feeding with liquid or substantially liquid solution 33 in order to make possible the spraying, at a predetermined flow rate D.

[0159] The system 31 thus comprises a tank 34 for storage of said liquid and means 35 for moving the liquid (metering pump) arranged in order to regulate the flow rate D of the liquid via a calculator 36 and also controls the other actuators employed in the device.

[0160] The tank comprises, in its bottom, a mixing means, for example a stirrer (not represented).

[0161] The coating gel is the curable liquid coating material obtained by the sol-gel process described above.

[0162] The device also comprises means 37 for heating the receptacle 13 which are known per se which make possible the rise in the temperature of a part of the internal surface of the receptacle up to a predetermined temperature threshold for the drying.

[0163] More specifically, the heating of the internal surface is carried out, for example, by direct radiation from heating resistors 38 positioned outside the receptacle or by diffusion around the wall of the receptacle positioned in contact, for example, with a heating muffle (not represented).

[0164] In one embodiment, the receptacle and the resistor are substantially confined in one and the same chamber so as to form an oven for homogeneous heating of the receptacle.

[0165] The device also comprises a computer or automaton 39 for digital control comprising the calculator 36.

[0166] These are connected via a data bus 40 and in a way known per se to the actuators of the device, namely to those of the retention clamp of the receptacle, that is to say of the motor for driving in rotation, to those of the means 24 for insertion of the nozzle 26 into the receptacle (jack), the stirrer, and also to those of the means 35 for moving/feeding with liquid (pump, valve, nozzle) and heating means 37 (electrical resistors).

[0167] The calculator 36 is arranged in order to calculate, from the different set points imposed, a law for controlling each of the actuators in a way known per se.

[0168] As is obvious and as also results from the above, the present invention is not limited to the embodiments more particularly described. On the contrary, it encompasses all the alternative forms thereof and in particular those where the device implementing the process is different.

[0169] The application can thus and for example be carried out by lettering or stamp.

[0170] The principle here is to use a stamp in the form of a letter or pattern made of rubber (sufficiently small to be introduced into the neck of the bottle) topped/soaked with sol-gel and then introduced at the end of a shaft (automated/articulated subsequently) into the bottle before being applied to the surface of the glass. The stamp is subsequently taken out again from the bottle. The sol-gel is subsequently dried normally, as described above.

[0171] The application of a layer which is reactive toward UV radiation to the internal surface, followed by exposure, can also be the process used. Use is then made of a gelatin with ammonium dichromate or diazidostilbene, for example, as additional additive, reactive pigments being added to the sol-gel.

[0172] The reactive pigments are added directly to the sol-gel, a negative is adhesively bonded to the external surface of the bottle and then a strong UV light is applied through the negative in order to develop the image; the excess is washed off before drying.

[0173] It is also possible to apply the reactive layer as above and then the transparent (or colored) sol-gel is applied as internal protective surface for the product present.

[0174] Another embodiment uses printing pins.

[0175] In this instance, the principle is as follows:

[0176] One of the pin-shaped printing valves is introduced via the neck. Control of the valve makes it possible to produce fine drops close to the interior surface (ink jet type), and thus to draw a pattern is possible by controlling the relative movement of the pin with respect to the surface and also the ejection of the drop. These pins are shape-memory pins; they can be curved in order to approach internal surfaces.

[0177] It is also possible to produce arched pins which can eject drops in a desired direction.

[0178] These valves (LeeCo) have a diameter of approximately 6 mm, being able to be completely introduced into the majority of bottles. Once introduced, these valves can be inclined (for example with a robot) in order to be able to discharge more accurately into the axis of the nozzles.

[0179] With the invention, and by using a spraying system and also an appropriate specific program, while sufficiently lowering the pressure of the spraying air, the system can thus eject droplets of greater size than in normal operation. Handling in this way makes it possible to produce a speckled effect never obtained to date.