Method for the manufacture of molded articles coated with a microfibrous material

Abstract: Composite product consisting of a leather-like microfibrous material and a polymer film, useful for coating cold injection molding manufactured articles in the same time of the manufacturing operations of said material.

Description: The present invention refers to composite products useful in the manufacture of coated formed articles and comprising microfibrous material coupled with a polymer film. More particularly the invention concerns a method for the manufacture of coated plastic material articles wherein a such composite product is used to constitute the article's coat. Woven or non-woven microfibrous leather-like materials, comprising synthetic polymer microfibers generally consisting of polyester or polyamide are known in the art. Said materials have the appearance of the natural leather and some among these materials, namely the ones in which a polymer microfibrous non-woven material is immersed in a polymer matrix, preferably polyurethane, exhibit "hand", lightweight, velour-like, fastness to light and nitrogen oxide characteristics even better than the natural leather. Moreover those materials, thanks to their good characteristics constitute a valuable product widely used in the garment industry, furniture manufacture, and interior decoration of vehicles, boats and other transportation equipment. In order to be suitable for the manufacture of furniture and for vehicle interior decoration the microfibrous material can be lined to a cloth, knitted fabric or polystyrene foam providing the product with the required stiffness and mechanical strength. Such a lining is carried out by means of suitable adhesive or by flame heating as it is disclosed in GB-A-2 235 651 and GB-A-2 235 652 of the Applicant. A field in which the microfibrous material could be widely used is the coating of formed articles made of more or less stiff material when said articles are obtained by the so-called "cold injection molding" process, as for instance in the manufacture of car instrument boards, car interior wallboards or posts and office chairs or arm-chairs. However the above mentioned microfibrous material lining techniques used in the coupling with clothes and foamed polymeric material are poorly consistent with the typical cold-injection molding article production cycles. In fact the use of the above techniques implies complex and lengthy operation steps affecting the economics of the production cycle. As a matter of fact the cold injection molding process consists of a liquid polymer injection, such a liquid polymer consisting of two or more components which react with each other within a mold and die system. Normally the polymeric liquid components are kept separated and are simultaneously injected into the mold through a plurality of extruders (one for each component) in order to prepare the mixture inside the mold. The component reaction takes place in a short time (about 2 minutes) and it results in a foamed polymer structure having the shape of the mold and die system. The coating of the above foamed polymer structure is obtained by placing the coating material (textile product or similar) into the mold prior.to the injection of the polymeric mixture, the coating being caused to adhere to the internal surface of the mold by vacuum suction technique. It has been found that when the microfibrous material alone is used as a coating, the pressure injected polymeric material may pass through its porous structure resulting in general defects on the coating surface. The composite products to be used according to the invention are capable to act as a coating of articles manufactured by the cold injection molding process and which retains the appearance qualities without being spoiled by the manufacturing process itself. It has been now found that a product consisting of a non-woven microfibrous material and a polymer film can be advantageously used to effectively constitute the coating of cold injection molding manufactured articles. It is the object of the present invention to provide a cold injection molding process for the manufacture of the abovementioned non woven microfibrous material coated polymeric articles. The composite material can be obtained by coupling the microfibrous material with an impermeable polymer film. The coupling can be effected with several processes such as gluing by means of an adhesive film inserted between the microfibrous material and the impermeable film; by flame coupling technique where the adhesive member is a thin layer of a direct flame melted foamed material; by powder coupling where the adhesive member consists of low melting point polymer powder placed between the microfibrous textile and an impermeable film, that have been heated by hot rolls or I.R. (infrared) ovens. A continuous coupling process for the microfibrous material and the impermeable film may be carried out using roller hot-press systems, an adhesive material (adhesive layer, melted foam, melted polymer powder) having been inserted between the layers. Microfibrous materials useful to carry out the process of the present invention and consisting of a microfibrous non-woven fabric essentially obtained from synthetic microfibers, are known in the art. For instance some of the above material, namely the ones consisting of a microfibrous non woven fabric immersed in a synthetic polymer matrix have been disclosed in the Italian Patents 823,055, 921,871, 839,921, 858,337, 905,222, and 873,699. Additional microfibrous, non-woven material manufacturing processes are disclosed in the Italian patents 1255570, 1255654, 1256232, 1256230 and 1255803 of the Applicant. EP-0497335-A (COMMER S.p.A.) is concerned with a process whereby a product thermoplastic material, i.e. a melt which will solidify upon cooling. Said reference does not disclose the use of a leather-like microfiber composite material of present claim 1. US-5277969-A (ALCANTARA S.p.A) is concerned with an imitation leather laminate comprising a base sheet and a functional substrate which may be a polymeric water-proofing film bonded thereto. The base sheet is more particularly a felt of µ-fibers treated with a polyurethane-polyurea resin and the water-proofing film is made of µ-porous polyurethane. The reference does not suggest the use of this imitation leather laminate in a cold injection moulding method to form a leather laminate coated article. EP-0744489-A (ALCANTARA S.p.A.) is not a pre-published patent literature but enjoys an earlier priority date and an earlier filing date than the present application. Claims 1-10 of the reference has a content similar of the present application. However, the reference does not teach the manufacturing of the composite product by cold injection moulding. JP-60199986-A (KURARAY), JP-04333674-A (KURARAY) and JP-58144184-A (KYOWA LEATHER CLOTH Co.) are concerned with the manufacture of artificial leather. No mentioned is made of the manufacturing articles by cold injection moulding. JP-55067444-A (MEIWA SANGYO) and EP-0497335-A (COMMER S.p.A.) refer to interior car lining; no mentioned made of a simultaneous cold injection moulding of the lining material and the article to be lined. Even if in the course of the present description reference will be specifically made to the use of microfibrous non-woven material immersed in a polyurethane matrix, the present invention is not limited to or by this component. Other microfibrous leather-like material can be used to coat cold injection molding manufactured articles in the same time as the molding operations thereof; in this respect reference can be made to microfibrous materials disclosed in Italian patent 1,085,966. Further leather-like microfibrous materials useful in the process according to the invention comprise non-woven fabric structure formed by different section or size microfibres on a woven or knitted carrier. Additionally included within the scope of the invention is the use of composites consisting of polymer film and a microfibrous material in which round or non round cross section microfibres form a woven or knitted fabric and the resulting product is submitted to raising process to impart the suede-like appearance. The microfibrous non-woven materials particularly suitable according to the invention are the ones whose matrix consists of a polymer selected among polyurethanes and derivatives thereof, the microfibres consisting of polyester (e.g. polyethylenterephthalate), polyamide, (e.g. nylon 6, nylon 66, nylon 12), polyolefins (e.g. polyethylene, polypropylene) polyacrylonitrile and copolymer thereof. The composite forming polymer film may be: Polyurethane mainly based on polyether and/or polyester and/or copolyester; Polyester, copolyesters Polyolefins, such as polyethylene or polypropylene; Polyamide, copolyamides. A particularly preferred film according to the present invention consists of copolyester of polyethylene therephthalate/isophthalate According to a preferred embodiment of the invention, the polymer film is coated with a removable protective layer of a high melting point polymer material, e.g. polyethylene, polypropylene or polyvinylchloride; such protective coating being removed before the molding operations. The cold injection molding operations to manufacture the microfibrous, non-woven lined article, using the composite material according to the invention, take a very short time, about 2 to 4 minutes, at a temperature ranging from room temperature to 40-50°C. The invention will now be illustrated in detail with reference to the following examples which are not to be intended as a limitation of the invention. Examples 1-19 are reference examples; examples 20-29 illustrate the claimed invention. Example 1 A microfibrous felt has been prepared in accordance with the following known procedure: The fiber was formed by 57 parts by weight of polyethyleneterephthalate, 40 parts by weight of polystyrene polymer and 3 parts by weight of polyethyleneglycol. The (3.8 den) 4.2 dtex extruded fiber revealed a 16 polyester microfiber content; each microfiber being approximately (0.10 - 0.11 den) 0.11-0.12 dtex. The fiber was submitted to punching to yield an intermediate felt of 0.195g/cm3 density and 540g/m2 weight. The intermediate felt was immersed into a 20% polyvinyl alcohol water solution, dried and treated with perchloroethylene to remove the polystyrene matrix obtaining a polyvinylalcohol matrix containing fiber. Polyurethane was prepared separately by reacting 4,4'-diphenyl-methane - diisocyanate (MDI)(2 mole) with 1 mole of a mixture of polytetrahydrofurane (PTHF)(molecular weight 1976) and polycaprolactone (PCL) (molecular weight 1958) in a molar ratio 3:1 at 65°C for a period of 3 hours. The resulting prepolymer was dissolved in dimethylformamide to yield a 25% (weight) solution. A 25% (weight) dimethylformamide (DMF) solution of 4,4'-diaminophenyl - methane (DAPM) (0.825 mole) and n-dibutylamine (DBA) 0.175 mole) was prepared and added to the diluted prepolymer at 65°C. The solution was reacted for approximately 30 hours until the concentration reached the value of 25% by weight and the solution was free from NCO groups. The resulting polyurethane solution exhibits a viscosity of approximately 20,000 mPa.s (cps) at 20°C. This polyurethane solution was diluted with DMF to obtain a 13% by weight solution, then the polyethylene terephthalate/polyvinyl alcohol felt prepared as described above was immersed into the polyurethane solution. The excess polyurethane was removed by passing the impregnated felt through squeezing rollers; polyurethane was then coagulated by pouring it in water to remove polyvinyl alcohol. After the above treatment the product was dried. The resulting material consists of 68±3% by weight of microfiber and 32±3% by weight of polyurethane. The product was lengthwise sliced in 10mm thick sheets and then submitted to abrasion to impart the suede-like appearance. Example 2 The procedure of Example 1 was repeated with the exception that the 25% by weight prepolymer in dimethyl formamide solution was reacted with, instead of DAPM, 1.65 mole of water containing 0.175 mole of n-butylamine. The extension reaction was carried out at 65°C for 6 hours. Resulting polyurethane average molecular weight was such as to impart to a 25% by weight dimethylformamide solution at a temperature of 20°C a viscosity of 20,000 mPa.s (cps). Example 3 The procedure of Example 1 was repeated with the exception that the fiber was prepared from a flame-retardant polyethylene terephthalate FIDION SR commercially available from ENICHEM FIBRE S.p.A. Example 4 The procedure of Example 1 was repeated with the exception that nylon 6 was used instead of polyethylene terephthalate and a styrene-acrylonitrile copolymer (marketed under the trade name SUN) was employed instead of polystyrene. Example 5 A product similar to Example 1 was prepared by using 4,4'dicyclohexyl methane instead of MDI and 4,4'-methylene bis (2,6-diisopropylaniline) instead of DAMP. Example 6 A product was prepared according to the procedure of Example 1 using nylon 6 instead of polyethylene terephthalate. Polyurethane was prepared according to example 5. Example 7 Microfibrous material prepared according to Example 1 was coupled with a copolyester based polyurethane film by using the flame technique where the adhesive material consists of a foamed polyurethane or polyester layer of approximately 2 mm thickness that has melted by a direct flame system. The three materials a) Microfibrous non-woven fabric, b)surface melted foamed material, and c) polyester film, have been passed through a roller hot-press system to improve the adhesion. Example 8 Microfibrous non-woven material manufactured according to Example 1 was coupled with a copolyester film using the Hot Melt technique wherein the adhesive material consists of low melting polymer powder, typically polyester or polyamide placed into a hot roller engravings or groves at a temperature higher than the powder melting point. The rotating hot roller deposits the "adhesive points" on microfibrous non woven fabric which in turn is immediately contacted with the copolyester base film in a roller hot-press system allowing a continuous coupling process. Example 9 Microfibrous non-woven material manufactured according to Example 1 was coupled with a copolyester film using the melting film gluing technique wherein the melting film is inserted between the microfibrous material and the copolyester base film. A hot-rollers hot-press system operated at such a temperature as to melt the melting film ensures the continuous coupling process. Example 10 The microfibrous product made of Nylon 6 and having a diameter varying around a mean value of 2 µm (the effective size ranging from 0,5 to 3,5 µm) immersed in a polyester matrix. The average microfibre count was (0,01 den) 0.011-0.012 dtex. The above microfibrous product was coupled with films according to the procedures of the examples 7, 8 and 9. Example 11 is void Example 12 The microfibrous product consists of isosceles triangle cross-section microfibres included into a woven or knitted structure. The suede like appearance is obtained by a conventional raising process. Said microfibrous product was coupled with films described in examples 7, and 9. Example 13 Following the procedures of examples 7, 8 and 9, composite products have been prepared comprising the microfibrous non-woven material manufactured according to Example 1 and polyethylene or polypropylene films. Example 14 Following the procedures of examples 7, 8, and 9 composite products have been prepared consisting of the microfibrous non-woven material manufactured according to Example 6 and polyester or polyether based polyurethane films. Example 15 Following the procedure of the preceding examples composite products have been prepared comprising the microfibrous non-woven material manufactured according to Example 4 coupled with a polyester or polyether based polyurethane film. Example 16 Following the procedure of the previous examples, flame retarding composite products have been prepared comprising the microfibrous non-woven material manufactured according to Example 3 and polyester or polyether based polyurethane films. Example 17 Following the procedure of Examples 7, 8, and 9 a composite product has been prepared comprising the microfibrous non-woven material manufactured according to Example 6 and a polyethylene film. Example 18 Following the procedure of Examples 7, 8, and 9 a composite product has been prepared comprising the microfibrous non-woven material manufactured according to Example 4 and a polyethylene film. Example 19 Following the procedure of the preceding examples, a flame retarding composite product has been prepared comprising the microfibrous non-woven material manufactured according to Example 3 and a low melting polyethylene film whose melting point is less than 150°C. Example 20 A mold suitable for the "cold injection molding" technique was coated with the composite manufactured according to Example 7, the suede-like side of the microfibrous non woven fabric being directed toward the mold. The composite product was adhered to the mold by vacuum suction, so that the composite coating perfectly fits to the mold and adhering to any minimum detail of the mold internal surface. Subsequently the die was applied to the mold to tightly close the mold edges to prevent any polymeric liquid leakage during the pressure injection operations. A polymer component mixture was injected under pressure into the mold and die system, the mold being internally coated by the composite manufactured according to example 7. Each component was separately injected through a single extruder. The reactant mixture reacts in a short time of the order of about 2 minutes, forming a foamed solid material having the shape of the mold and die system and coated by the non woven microfibrous material from the mold side. Examples 21 and 22 The procedure according to example 20 was followed using the composite products manufactured according to examples 8 and 9. Examples 23, 24, 25, 26, 27, 28, and 29 The procedure according to example 20 was followed using the composite products manufactured according to examples 13 to 19.

Claims: Process for the manufacture of a coated plastic material article by cold injection molding technique, using a composite product consisting of a leather-like microfibrous non-woven material and a polymeric film to form the coat, wherein said composite product is disposed against the wall of a mold and cold injection is then conducted to form a coated molded article showing the microfibrous material on its surface. Process according to claim 1, characterized in that the leather-like microfibrous material consists of non-woven polyester microfibers immersed into a polyurethane based matrix. Process according to claim 1, characterized in that the leather-like microfibrous non-woven material consists of nylon 6 or nylon 66 microfibers immersed into a polyurethane based matrix. Process according to claim 1, characterized in that the leather-like microfibrous non-woven material consists of flame retarding polyester microfibers immersed into a polyurethane based matrix. Process according to claim 1, characterized in that the microfibrous leather-like material consists of non-woven structure obtained from different cross section shape or size microfibres and an internal or external woven or knitted fabric carrier. Process according to claim 1, characterized in that the microfibrous leather-like material consists of a knitted or woven structure essentially made of microfibres, submitted to raising process. Process according to any of the preceding claims characterized in that the polymer film material is selected among: Polyester or polyether or copolyester mainly based polyurethanes; Polyesters or copolyesters; Polyolefins as polyethylene or polypropylene; Polyamides or copolyamides. Process according to claim 7, characterized in that the polymeric film consists of a polyethylene terephthalate-polyethylene isophthalate copolyester. Process according to any one of the preceding claims characterized in that the polymeric film has a thickness of 0.30 to 0.80 mm. Process according to any one of claims 1-9, characterized in that the composite product is placed in an open mold, the side to be supported by the cold injected material being directed toward the interior of the mold and die system and then adhered to the mold wall by vacuum suction, and the mold and die system is tightly closed to resist to liquid polymeric mixture pressure injection. Process according to any one of the preceding claims characterized in that the polymer film is protected by a polymer material layer having a higher melting point as polyethylene, polypropylene or polyvinyl chloride that is removed before the injection molding operations. Use of a composite product consisting of a leather-like microfibrous material and a polymeric film in the manufacture of coated plastic material articles according to the process of anyone of claims 1 to 10.

Inventors: FERRARO CRISTOFERO, FERRARO, CRISTOFERO
Applicants: ALCANTARA SPA, ALCANTARA S.P.A.
Application year: 1996
Main classification: B32B27
IPC codes: B29C45, D06N3, B32B27