SANITARY WARE THUS OBTAINED”

DESCRIPTION

TECHNICAL FIELD OF THE INVENTION

[001] The present invention relates to a process for producing bathroom or kitchen sanitary ware comprising processing steps that are advantageously simple and effective in obtaining a product in a versatile, flexible and standardised manner. In particular, the invention relates to a process which considerably reduces the number of operating steps as well as a strong decrease in the use of solvents and ensuing decrease in emissions. Furthermore, the final product is technically different while maintaining, if not improving, the performance.

PRIOR ART

[002] In the residential or hotel bathroom and kitchen sanitary ware industry, processes and technologies for producing articles such as sinks, bathtubs or shower trays made of composite material have been known for a long time.

[003] Usually, these processes generally use metal or composite moulds based on glass or carbon fibres bonded together by means of epoxy or polyester resins. The moulds are generally filled with a mixture of thermosetting or thermoplastic resin, such as for example acrylic, polyester, epoxy resins and combinations thereof, optionally in association with mineral fillers, polymeric fillers, catalysts, stabilising additives and/or coloured pastes (called mixture hereinafter).

[004] The first step is to deposit a layer of gelcoat comprised between 0.5 and 2 mm on the surface of the mould. The gelcoat is sprayed by means of manual or automated processes. Gelcoat is a known liquid product based on polyester, vinyl ester and/or epoxy resin which confers aesthetic characteristics and stain resistance to the final product. After said spraying, there follows a step for drying the gelcoat in an oven at a temperature comprised between 25° and 65°C and a period of time comprised between 30 and 90 minutes. The mould may be closed just before or immediately after the drying step. Then, the mixture is injected into the mould after the drying step. The mixture can be injected by gravity or pressure.

[005] The article is the de-moulded after filling the mould with the resin mixture, and after the time necessary for the hardening of the mixture has elapsed. Subsequently, optionally, an oven hardening is possibly carried out at a temperature and for a period of time which allow a complete catalysis/polymerisation. The time may vary between 1 and 4 hours and the temperature varies between 50° and 120°C.

[006] After forming by moulding, the final article consists of a structural body consisting of the polymerised mixture and a surface coating (gelcoat) in contact with the user and adhering to the structural body by means of a sort of mechanical/chemical interpenetration/bond between the two materials forming said body and said coating. [007] Although the aforementioned technology is widely used, it reveals drawbacks linked to various factors such as the emission of solvents and organic substances linked to the gelcoat polymerisation steps, a high level of labour linked to the cleaning, sanding and/or polishing steps necessary to finish the product on the surface covered with the gelcoat, a high number of wastes linked to problems inherent in this technology such as: uneven spraying with ensuing areas with gelcoat accumulations or areas with an insufficient amount of gelcoat, pollution in the processing rooms such as powders that come into contact with the gelcoat, depositing on the mould, thus jeopardising the finishing step or rendering the piece waste material, problems related to catalysis on the gelcoat caused by the equipment used to deposit it on the mould, delamination of gelcoat from the body caused by incorrect temperatures or times in various steps.

[008] US2006147655 describes a non-porous solid surface structure comprising a thermoplastic, flat, unitary and non-porous polymeric matrix made of polymethylmethacrylate, polyvinylchloride, polycarbonate or combinations thereof, and a visible decorative object permanently fixed to the matrix, wherein the decorative object extends at least on one edge of the matrix. In particular, the thermoplastic matrix, in the form of two sandwich layers on the decorative object, is unitary, i.e., a single non- laminated piece. Furthermore, the production process specifies that said two layers are subjected to two separate heating and forming pressure processes, at a softening temperature lower than a possible coating film applied by interposing glue.

[009] A product thus obtained is structurally complex on the one hand and on the other hand equally complex to manufacture due to the number of steps to be carried out which can easily increase the risk of errors which result in defects of the final product. SUMMARY OF THE INVENTION

[0010] Thus, the technical problem underlying the present invention lies in providing a method for producing bathroom or kitchen sanitary articles alternative to the process described above so as to avoid the aforementioned drawbacks.

[0011] Such problem is solved by a process comprising simple production steps that drastically reduce the use of toxic substances. [0012] Thus, a first object of the present invention is a process for producing bathroom or kitchen sanitary ware without the gelcoat deposition step and unnecessary heating steps. [0013] A second object is a process provided with standardisation of the production steps with ensuing reduction of the waste, flexibility of manufacture of the articles and reduction of manpower.

[0014] A further object is an article that can be obtained according to the process of the invention.

[0015] An even further object is a plant for the production of the article.

BRIEF DESCRIPTION OF THE FIGURES

[0016] Further characteristics and the advantages of the process and of the article of the invention will become more apparent from the following description of an embodiment provided purely by way of non-limiting example with reference to the following figures, wherein:

- figure 1 represents a schematic view of a plant for the production of an article according to the invention;

- figure 2 represents a schematic view of a first processing step of the process of the invention;

- figure 3 represents a schematic view of a second processing step of the process of the invention;

- figure 4 represents a schematic view of a third processing step of the process of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0017] The idea underlying the invention was to find a process that considerably reduces the use of polluting and toxic substances, as well as the laborious finishing steps of an article made of composite material, particularly for sanitary use, or further steps which are not necessary or even at risk of causing defects in the finished product.

[0018] In order to implement such idea, there was conceived the idea of eliminating the step of applying the gelcoat, a product known to be prepared with solvents and organic highly toxic and polluting substances required for the polymerisation.

[0019] However, the step of eliminating the gelcoat deposit must in any case be replaced by a finishing step necessary to coat the mixture of thermosetting/thermoplastic resins which - as such - should not come into contact with the skin of a person and it is devoid of stain resistance characteristics and it does not impart the sought-after aesthetic effects. [0020] The solution that was found consists in replacing the gelcoat with a layer, film or sheet of plastic material produced in a preliminary step and subsequently glued onto the structural body of the article.

[0021] Thus, the production process according to the present invention comprises the steps of:

- providing a shaped-structural body made of thermosetting or thermoplastic resin;

- providing a plastic film having a thickness comprised between 0.1 and 2 mm consisting of a material comprising PVC, PET, PMMA, PE, PP and mixtures thereof;

- applying a layer of glue onto a first surface of said plastic film or to the shaped cavity of said structural body;

- heating said plastic film up to a temperature such to obtain a degree of softening sufficient to allow deposition without stretching or air pockets;

- positioning said heated plastic film to close the shaped cavity of the structural body to be coated with said layer of glue facing toward said cavity or with the glue layer on said cavity of the structural body;

- applying a pressure onto the surface of said plastic film opposite with respect to the one facing toward the structural body and a vacuum on the side of the structural body opposite to the one receiving the film so as to fully and uniformly adhere said plastic film to said structural body causing the gluing of the mutual contact surfaces.

[0022] The first step of providing the structural body comprises the moulding of a mixture of thermoplastic or thermosetting resins according to technologies known in the plastic moulding industry.

[0023] In general, moulding consists in providing a mould usually made of metal material such as steel or alloys thereof, alternatively made of composite material based on glass or carbon fibres bonded together by means of epoxy or polyester resins or mixtures thereof. Preferably, the surface of the mould is previously covered with a layer of release material such as for example starches, stearates, silicone resins, mineral powders.

[0024] Hereinafter, the mould is closed and a mixture of thermosetting or thermoplastic resins is injected thereinto, possibly in association with mineral and/or polymeric fillers, catalysts, additives and/or coloured pastes.

[0025] In any case, the most commonly used resins part of said mixture are preferably selected from acrylic resins, polyester resins, epoxy or polyurethane resins. [0026] Mineral fillers could include calcium carbonate, aluminium trihydrate (ATH), quartz, phyllite; additives may for example include glass fibre, graphite, talc, natural fibres, accelerators; the most common catalysts include organic peroxides; the coloured pastes consist of a mixture of thermosetting and/or thermoplastic resins and natural pigments such as for example titanium dioxide for white.

[0027] The aforementioned mixture is usually injected by gravity, or at a pressure comprised between 0.5 bars and 4 bars, at a temperature comprised between 20°C and 50°C and left there for a period of time comprised between 20 min and 120 min.

[0028] At this point, the article obtained is de-moulded, i.e., removed from the mould and possibly subjected to an oven hardening step for the completion of catalysis/polymerisation for a period of time comprised between 1 and 4 hours at a temperature between 50°C and 120°C. This hardening step is carried out or not carried out depending on the formulation used for the mixture. As a matter of fact, it is known that if the appropriate hardening catalysts and/or additives are not used, the aforementioned heating step is carried out to ensure a 100% complete catalysis.

[0029] A structural body of the article ready to be subjected to the subsequent step of applying a plastic film is obtained at the end of the aforementioned steps.

[0030] At least one through hole on the structural body for example forming the hole for housing a drain of a shower tray, sink or bath tub of bathroom or kitchen sanitary ware is preferably provided before said application, through a mechanical process. Furthermore, the surface of the body that will receive the plastic film is treated so as to receive the film adequately. In particular, the treatment consists in sanding the surface that will receive the film with sandpaper with grit comprised between 80 and 600. Sanding may be carried out manually or using an orbital disc sander. Alternatively, the surface may be sandblasted with quartz or calcium bicarbonate or polymer grit or it can be cleaned with descaling agents and/or chemical cleaners/solvents. The purpose of this step is to remove any residues of release agent deriving from the moulding process and more generally to make the surface suitable for gluing.

[0031] The subsequent step of applying the layer of glue on a first surface of the plastic film, opposite to the possible surface with particular aesthetic treatments, comprises the use of a one or two-component glue preferably selected from epoxy, acrylic and polyurethane glues. In general, such glues are applied by spraying or specific application machine, and are dried for at least 30 minutes at ambient temperature.

[0032] The plastic film is selected from those already available on the market and generally used for the coating of furniture or parts thereof, such as for example films based on PVC, PE, PET or other materials. The type of material that constitutes the film depends on the desired performance, such as resistance to stain, chemical agents, aesthetic and touch characteristics, and many others. This plastic film (also known as polymeric sheet) may or may not have a surface texture (which for example reproduces wood grains) and it may come in various colours. The surface may be glossy or opaque. Preferably, the thickness ranges from 0.2 to 1 mm.

[0033] Alternately, the step of laying the glue sheet is carried out onto a first surface of the film layer, opposite to the surface having eventually particular aesthetic treatments, and, such as the step of directly applying onto the cavity of the shaped body, comprised the use of a mono or bi-component glue preferably selected form epoxydic, acrylic, polyurethan glues. Generally, said glues are sprayed or laid with a specific applying machine.

[0034] Once the film has been prepared, eventually with the glue, it is subjected to the heating step, whose temperature is around the HDT value of the polymer forming the film, a value calculated according to the ISO 75 and ASTM D648 protocols. Preferably, such temperature is comprised between 80°C and 150°C, more preferably between 70°C and 100°C for a period of time comprised between 10 seconds and 2 minutes. In particular, heating is carried out in a differentiated manner. As a matter of fact, it has been observed that in order to obtain a better adhesion of the film on the structural body, especially at curves or corners, the heating must be greater to allow a greater softness/plasticity which allow the film to lie more precisely at changes in surface or, in other words, on non-planar surfaces of the structural body or farther away from the heat source. The variation of the thermal energy power at the aforementioned most critical points will depend on the thickness and on the type of material used for the film. In any case, these types of adjustments are known to the man skilled in the art.

[0035] The film thus prepared is positioned so as to close the cavity of the shaped structural body to be coated eventually with its side covered with glue directed toward said cavity.

[0036] At this point, a pressure is applied on the plastic film preferably comprised between 1 and 6 bars, more preferably between 2 and 4 bars, by fluxing compressed air and vacuum preferably between -0.2 and -0.8 bars on the side of the structural body opposite to the one for receiving the plastic film by means of a vacuum pump. This step is carried out in a sealed chamber, as explained hereinafter, which allows to create an overpressure space where the film is pressed against the surface of the cavity of the structural body and an under-pressure space where the film is sucked against said surface. Basically, said actions, which are activated in combination on two opposite sides of the film, allow to obtain a perfect adhesion between the two components of the article in a very simple but considerably effective manner, avoiding the many steps due to the application of gelcoat as well as its environmental impact or multiple heating operations. In particular, the vacuum application step is carried out first and the pressure application step is carried out for 20-70 seconds after a period of time comprised between 10 and 60 seconds. This specific combination has proved to be surprisingly effective in that the adhesion of the polymeric film with the layer of glue on the structural body is optimal and i.e. free of undesired creases given by the non-balanced adhesion in all the points of the shaped structural body and also free of air bubbles caused by non-uniform adhesion. In other words, both the aforementioned heating step with differentiated areas and the combination of pressure and vacuum allow to obtain an optimum degree of softening in the entire film so as to perfectly adapt to the whole shaped surface of the structural body without causing stretching, with formation of bubbles, or excessive softening, with formation of creases.

[0037] The product obtained is therefore a moulded article comprising a structural body in a mixture of thermosetting or thermoplastic resin covered - on a first functional surface - by a plastic film applied by interposing a layer of glue.

[0038] A product thus obtained differs from the aforementioned products in that the structural body of the prior art is covered by a layer of gelcoat which is directly applied on a surface of said body without interposing glue but through physical/mechanical interpenetration into the material that forms the body.

[0039] According to a further object of the invention, the process for producing articles for bathroom or kitchen sanitary ware is preferably carried out with a plant 1 , schematically shown in figure 1 , comprising:

- a station 2 for moulding a shaped-structural body made of a mixture of thermosetting or thermoplastic resin, and eventually for applying a layer of glue onto the cavity of said shaped body;

- a station 3 comprising elements 22 for heating said film with glue eventually comprising means for applying a layer of glue onto a first surface of said film;

- a station 4 for covering the structural body with said film by applying pressure onto the surface of said plastic film after said film is positioned to close the cavity of the shape of said structural body, and applying vacuum onto the surface opposite the cavity of said shape. [0040] Preferably, the moulding station 2 consists of an entirely conventional plastic material injection mould which will therefore not be described and illustrated in detail hereinafter. The operating parameters of the mould will be as described above with reference to the process.

[0041] According to a preferred embodiment, before passing to the covering station, the structural body may be treated in a finishing station (not shown) in which the functional surface of the structural body is cleaned to eliminate traces of release agent. This station comprises per se known automatic or manual devices of the mechanical type such as sanding machines or sandblasting machines, or cleaners of the chemical type. Moreover, within said station, the cavity of the body can be covered of glue by means of conventional or robotic spraying guns or rollers.

[0042] The heating, and eventually applying glue station 3, schematically shown in figure 2, consists of a support or frame 20 provided with grippers or clamps 21 adapted to keep the film 10 tensioned until it is substantially flat but without causing stretching. At this point, a heating element 22 is positioned close to the film surface, or the same film can be moved in a heating station or oven (not shown), where said frame is positioned close to a coil, infrared lamps or a heated-air blower to heat the film, eventually with the glue, at a temperature and for a time as disclosed above and preferably at the differential condition disclosed above. Eventually, the station 3 can comprises an entirely conventional spray gun or roller system (not shown) which deposits a layer of glue as described in the previous process on either side of the film.

[0043] The frame 20 with the heated film 10 is then brought to the station 4 for covering the structural body 11 . This station comprises a sealed chamber 30 inside which the shaped structural body 11 suspended on a support 13 is first positioned and then the frame 20 with the film provided with glue is subsequently positioned so as to close the cavity 12 of the shape of the structural body.

[0044] As shown in figure 4, the chamber 30 is closed and a pressure is applied to the film by means of a blower (not shown) which presses the film against the surface of said cavity 12 and a vacuum pump (not shown) suctions air from the side of the structural body opposite to the one for receiving the film through one or more holes obtained in the thickness of the structural body. The operating parameters of the blower and the vacuum pump are those indicated in the process. Preferably, first the vacuum pump is activated followed by the blower which presses the film as specified above. [0045] The plant 1 can then comprise a last station (not shown) for removing the excess material both of the structural body 11 and of the film 10 by means of entirely conventional numerical control machines or manual methods.

[0046] In the light of the above, it is clear that all the drawbacks noted above with reference to the prior art have been overcome while major advantages have been achieved at the same time.

[0047] First and foremost, the step of applying gelcoat which, as explained, besides being laborious also entails the use of polluting substances and forces the operator to various preparation, deposition, drying and finishing steps, was eliminated.

[0048] There is therefore no longer a need to handle substances that are harmful to human health and to the environment.

[0049] Contamination of the mould for forming the article with the gelcoat, which therefore does not have to be cleaned after each production step, is also avoided.

[0050] The application of the plastic film advantageously allows to standardise the production with strong increases in productivity and great speed and ease in making the product versatile thanks to the immediate availability of films with functional and aesthetic characteristics ready for application.

[0051] The subject matter described above leads to the reduction of waste with major environmental impact.

[0052] The aforementioned versatility allows to provide articles with colours and/or textures diversified when required according to specific preferences or requirements. [0053] As described, the processing steps are considerably reduced and become simpler with advantage both in terms of costs and production times.

[0054] The application of a preformed plastic film on a structural body by gluing also has the advantage of combining the resistant mechanical characteristics of the structural body with the resistant chemical, aesthetic and hygienic characteristics of the plastic film in order to overcome the requirements of the regulations in force.

[0055] The implementation of a single heating step of the plastic film only, preferably in areas with a differentiated temperature and in combination with the subsequent vacuum and pressurisation steps, allows to obtain the best possible full adhesion of the film on the structural body and simultaneously avoid undesired stretching of the film which could affect its functionality.

[0056] The process, the article and the plant of the present invention may be subjected - by the man skilled in the art - to variations and modifications but without departing from the scope of protection as defined by the attached claims.