WO2011086237A1

WO2011086237A1 - Method for coating material article with coating composition and method for manufacturing injection moulded product and injection moulded product

Info

Publication number: WO2011086237A1
Application number: PCT/FI2011/050024
Authority: WO
Inventors: Samantha Kiljunen; Harri Kosonen; Liisa Lehtinen; Ari Kinnunen
Original assignee: Upm-Kymmene Wood Oy
Priority date: 2010-01-13
Filing date: 2011-01-13
Publication date: 2011-07-21
Also published as: EP2523788A1; EP2523788A4; WO2011086238A1

Abstract

The invention relates to a method for coating a material article with a coating composition.In accordance with the invention the material article is formed by a injection moulding and the material article is encapsulated with the coating composition, the coating composition contains at least one polymer and a coupling agent having reactive groups with the material article, and the coupling agent is activated to its active state in connection with the injection moulding to form chemical bonds between the material article and the coupling agent. Further, the invention relates to a corresponding method for forming an injection moulded product and a corresponding injection moulded product.

Description

METHOD FOR COATING MATERIAL ARTICLE WITH COATING

COMPOSITION AND METHOD FOR MANUFACTURING INJECTION MOULDED PRODUCT AND INJECTION MOULDED PRODUCT

FIELD OF THE INVENTION

The invention relates to a method for coating a material article with a coating composition as defined in the preamble of claim 1 and a method for manufacturing an injection moulded product as defined in the preamble of claim 16 and an injection moulded product as defined in the preamble of claim 25.

BACKGROUND OF THE INVENTION

Known from prior art are various plywoods, veneer boards or the like. Known from prior art is the gluing of veneers by various glues, e.g. polyurethane or phenolic glue, for providing a plywood or the like. Further, known from prior art is different types of methods for manufacturing plywoods. Further, known from prior art are different coatings for the wood boards and plywoods. From the previous applications

PCT/FI2009/050132 and PCT/FI2009/050663 are known different films for using as glues or coatings.

US 6645336 disclose the utilisation of extrusion coating.

EP1733804 discloses the utilisation of extrusion to form a bond between the molten polymer and epoxy or some other adhesive applied to wood prior to extrusion. The aim is to solve the problem of improving the adhesion. The patent refers to maleic acid and anhydride as polymer modifiers but they also state that this modification is not enough and the overall adhesion is not good enough. Instead the modification is utilised to get better adhesion between the epoxy and molten polymer.

Further, known from prior art is an injection moulding. The injection moulding is a manufacturing technique for making parts from plastic material. Molten plastic is injected at high pressure into a mould, which is the inverse of the desired shape. The mould is made by a mould maker from e.g. metal. Injection moulding is very widely used for manufacturing a variety of parts, from the smallest component to entire body panels of cars.

Further, known from prior art is an injection moulding of inserts.

US 4162138 discloses an injection moulding where inserts are used.

OBJECTIVE OF THE INVENTION

The objective of the invention is to disclose a new type of method for coating a material article with a coating composition. Further, the objective of the invention is to disclose a new type of method for manufacturing an injection moulded product. Further, the objective of the invention is to disclose a new type of an injection moulded product.

SUMMARY OF THE INVENTION

Methods and an injection moulded product according to the invention are characterized by what is presented in the claims.

The invention is based on a method for coating a material article with a coating composition. In accordance with the invention the material article is encapsulated with the coating composition by a injection moulding, the coating composition contains at least one polymer and a coupling agent, and the coupling agent is activated to its active state in connection with the injection moulding to form chemical bonds, e.g. covalent bonds and ester bonds, between the material article and the coupling agent, in preferable embodiment in the molten state. The coupling agent has reactive groups which are reactive with the material article and specially are reactive with the reactive groups, e.g. -OH, -0 or -H groups or the like groups, of the material article.

Further, the invention is based on a method for manufacturing an injection moulded product, wherein a material article is coated with a coating composition. In accordance with the invention the material article is encapsulated by the injection moulding and the material article is encapsulated with the coating composition containing at least one polymer and a coupling agent which has reactive groups being reactive with the material article, and the coupling agent is activated to its active state in connection with the injection moulding to form chemical bonds between the material article and the coupling agent in order to form the injection moulded product .

Further, the invention is based on an injection moulded product, which is formed by an injection moulding and is coated with a coating composition. In accordance with the invention, the material article is encapsulated with the coating composition containing at least one polymer and a coupling agent which has reactive groups being reactive with the material article, and the chemical bonds are formed between the coupling agent and the material article in order to form the injection moulded product .

The invention is specifically based on the encapsulation of the material article with the coating composition by the injection moulding. Preferably, the coating composition is a molten chemically activated polymer composition so that the overall adhesion is excellent and consists of a combination of physical and chemical bonding, e.g. covalent bonding. The method of the invention makes it possible to encapsulate a material article with polymer composition without separate coating manufacturing and gluing. The coupling agent in the polymer melt is activated during the injection moulding or activated before the injection moulding by utilizing heat, e.g. more than 190 °C, and/or with or without a catalyst and then chemically bonded, e.g. covalent bond, with the material article. By the invention it is created a product, e.g. a wood based product, which is strong and water resistant.

In this context, an encapsulation means any encapsulation, coating or the like process in which the coating comprising the coating composition of the invention is provided onto a material article or onto a part of the material article.

In this context, a material article can be any article, product, pre product, intermediate product or a part of the material article or product. In one embodiment the material article can be selected from the group: a veneer, a board, a layered board, e.g. plywood, a wood article, a part of the wood board, timber, beam, a composite article, a formable product, a fiber product, and their combinations or the like. In one embodiment the material of the material article is selected from the group: natural based material, wood, wood based material, cellulose based material, metal, plastic, plastic based material, composite material and their combinations. Preferably, the material article contains fiber based material, e.g. natural fiber based material, wood based material, paper based material, cellulose based material or their combinations. In preferable embodiment the material article is a layered structure, such as a layered board, plywood, veneer structure, sandwich structure or layered composite structure. The layered structure can be a formable layered structure. Preferably, the layered structure is formed of a number of layers, preferably veneer layers, in which the layers are laid one upon the other and glued together. The layers can be glued together by any adhesive or adhesive film. In one embodiment the layers can be glued together by polymer based adhesive. In one embodiment the layers can be glued together by thermoplastic based adhesive. In one embodiment the layers can be glued together by thermo moldable adhesive. In one embodiment the layers can be glued together by the adhesive based on the coating composition of the invention. A veneer refers to any veneer or any layers of a layered structure. The veneer can be formed of any material, e.g. natural based material, wood-based material, e.g. birch, spruce, pine, Eucalyptus, bamboo or any wood species, cellulose based material, paper, fiber material, composite material, non-woven material, metal, metal based material, plastic, plastic based material or their combinations or the like. In this context, the veneer refers to any layer of the layered structure. The thicknesses of the veneer layers can vary. Typically the veneer is a thin layer. In one embodiment the sandwich structure consists of different layers so that for example foams, wood or non-wood sponge honeycomb, metal and other light materials are sandwiches between veneers to create light strong structure.

In this context, an injection moulded product can be any material article, formable product, wood board, panel product, layered board, such as plywood, layered composite product or the like, or their combination or the like which is encapsulated with the coating composition. In a preferable embodiment material article is completely encapsulated with the coating composition to create the injection moulded product which is highly water resistant. The injection moulded product can be formable and be formed into very many shapes from the smallest to complete car body parts. Shaping of the material article containing thermoplastic can take place before, during or after the injection moulding.

In one embodiment the material article is encapsulated by coating with the coating composition. In one embodiment at least one surface of the material article is coated with the coating composition. In one embodiment one surface of the material article is coated with the coating composition. In one embodiment more than one surface of the material article is coated with the coating composition.

In one embodiment the material article is encapsulated in whole by the coating composition. In one embodiment the material article is edge sealed by the coating composition of the polymer and activated coupling agent. In one embodiment the coating composition is only applied to the edges of the material article, e.g. wood board, in the injection moulding in order to encapsulate the material article.

In one embodiment the material article consists of at least one insert which is encapsulated with the coating composition in connection with the insert injection moulding. In one embodiment the material article consists of inserts, e.g. veneers, layered board, formable layered board, plywood, formable plywood, sandwich structure, paper, paper board or composite inserts. The material article is placed as inserts into moulds for example manually or by robots. The coating composition is injected or extruded into the mould for encapsulating the inserts. Again the coupling agent is activated to its active state in order to obtain strong bonds between the insert and polymer. Alternatively, the material article, e.g. plywood, inserts can already be pre-coated with polymer, e.g. with polymer films or extrusion coating, which forms the basis for the hot molten coating composition to adhere to.

In this context, an injection moulding means any injection moulding, encapsulation, injection insert moulding, such as insert moulding, insert mould labelling, skin insert moulding, cap insert moulding, film insert moulding, in mould labelling, in mould decoration, in mould lamination, back moulding, thin film back moulding, or the like.

While wood is strong, light and inexpensive compared to many materials it possesses many undesirable properties such as high moisture movement, rotting and loss in strength in outdoor applications. Also, wood is not very dimensionally stable and twists and warps with change in moisture movement. On the other hand polymer is very long lasting and water resistant; however it is heavy, not very strong and expensive. By combining these materials it is possible to create a material possessing the properties of both materials. Injection moulding is one such technique. Wood and other wood based materials, cellulose and natural materials including paper and paper board can benefit from an encapsulation. In addition to this sandwich structures where the structure is partially wood and partially other material can also benefit from the encapsulation. By utilizing wood board inserts in injection moulding will allow for the best properties of the wood board, e.g. strong mechanical properties, and the water resistance properties of plastic to be combined for creating a strong versatile engineering composite.

In one embodiment polymer of the coating composition is selected from the group: polyethylene, e.g. LLDPE, LDPE, MDPE, HDPE, polypropylene, bio- plastics, petrochemical based plastics, other suitable polymer and their copolymers and block copolymers and their combinations. Polymers can contain also polyethylene terephtalate, polyamide, polystyrene, polycarbonates, vinyl plastics, acrylics, cellulosics and their combinations or other injection mouldable polymers. In one embodiment a melt index of the polyethylene is in the range 0.2 - 30 g/ 10 min being measured by the method ASTM D 1238 (condition E) , especially in the range 2 - 10 g/10 min (LLDPE and LDPE) and 4 - 15 g/10 min (MDPE and HDPE) being measured by the method ASTM D 1238 (condition E) . In one embodiment suitable polypropylenes for using in the coating composition are polypropylenes where the melt index is preferably in the range 10 - 80 g/10 min and especially in the range 7 - 15 g/10 min measured by the method ASTM D 1238 (condition L) .

In one embodiment the coating composition contains polymer which is selected from the group: bio-plastics and especially bio-plastics with properties similar to polyethylene and polypropylene. In one embodiment the coating composition contains polymer which is selected from the group: thermoplastic polymers, hot-melts, thermoplastic hot- melts, reactive hot-melts including polyurethane and their combinations with polyolefins, e.g. with polyethylene, polypropylene and their copolymers.

In one embodiment foamable thermoplastics can be used in the coating composition and therefore a blowing agent must be added into the thermoplastic. The polymer needs to be injected into the mould at temperatures above the activation temperature of the blowing agent. In addition to the above it is possible to cross-link the polyethylene version by radiation treatment or silane cross-linking. The cross-linked version will be heat resistant and wear resistant and resist a greater impact.

In one embodiment the material article contains thermoplastic material or thermoplastic polymers. In one embodiment the material article is a formable article containing thermoplastic material. In one embodiment the thermoplastic material is provided as glue-line between the material layers of the material article. In one embodiment the material article is a thermoplastic bonded layered structure. The formable product can be shaped before, during or after the injection moulding.

In one embodiment the coating composition includes coupling agent less than 20 % by weight, in one embodiment between 0.1 - 10 % by weight. In one embodiment the coupling agent includes organic coupling agents, e.g. isocyanates, amides, imides, acrylates, epoxides, anhydrides, organic acids, monomers and polymer, inorganic coupling agents, e.g. silicates, organic-inorganic coupling agents, e.g. silanes and titanates, and/or their combinations. The invention is not limited to these only. One preferred coupling agent for the invention is anhydride grafted polyolefin.

In one embodiment the coupling agent is reactive with -OH, -H and/or -0 groups of the material of the material article, e.g. wood or cellulose.

For example, wood is a porous material and therefore the strength of the thermoplastic adhesive bond will be a combination of both interlocking and charge interactions but the more covalent bonds the higher the overall adhesive strength will be. In order for the wood bond to be durable for exterior applications the adhesive needs to be wetting and of low enough viscosity to penetrate the wood and also to form a covalent bond with wood. With exiting adhesives there is no proof of chemical bonding and therefore bonding is only a combination of interlocking and weak forces, which explains why quite many of them fail for exterior applications. In the case of phenol formaldehyde resins covalent bonding with wood is not important as the adhesive penetrates the wood cell wall. However, in the case of thermoplastics penetration in to the cell wall is not possible and therefore to create a bond that will be durable requires also a durable chemical bond, e.g. covalent bond. The bonding mechanisms are not self-excluding and several may be occurring at the same time in a given adhesive bond depending on the circumstances. Therefore the strength of the thermoplastic adhesive bond will depend on both interlocking and charge interactions but the more covalent bonds the higher the overall adhesive strength will be. Without a coupling agent polyethylene only forms physical bonds and no chemical bonds and for the physical bonds to even function at all there would need to be deep penetration, i.e. need very thick films.

In one embodiment the coupling agent is maleic anhydride. In one embodiment the coupling agent contains maleic anhydride. In one embodiment the coupling agent is maleic anhydride grafted polyolefin, e.g. MAPP (maleic anhydride polypropylene) or MAPE (maleic anhydride polyethylene) . In one embodiment, maleic acid is converted to maleic anhydride during the activation in the injection moulding or during the manufacturing of the coating composition. In one embodiment the amount of the maleic anhydride- polyolefin added in the process of making the coating composition can vary between 1-10 %, typically 1-5 %, and preferably 2-3 % is sufficient.

In one embodiment the coupling agent is selected from the group: grafted silanes, grafted isocyanates, grafted epoxy groups, maleic anhydride grafted polyolefin, maleic anhydride grafted copolymer and their combinations. The invention is not limited to these coupling agents only, they are only examples. In one preferable embodiment the coupling agent forms covalent bonds, ester bonds and/or covalent bonds via esterification with the material of the material article, e.g. celluloses -OH groups, and/or with the polymer of the coating composition. In other words the coupling agent can form also other bonds.

In one embodiment the coating composition contains recycled material, such as waste material. In one embodiment the coating composition contains recycled material from labels and food packing. In one embodiment the coating composition contains waste label material. In one embodiment the recycled material includes at least a part of polymer needed in the coating composition.

In one embodiment the material article is en- capsulated with the coating composition containing waste label material. In one embodiment the material article is encapsulated with the coating composition containing waste label material and coupling agent, e.g. maleic anhydride. In one embodiment the waste la- bel material includes at least a part of coupling agent needed in the coating composition. In one embod^¬ iment the coupling agent is substantially included in the waste label material. In one embodiment the cou^¬ pling agent is included in the waste label material and additional coupling agent is added into the coat^¬ ing composition. Further, the coating composition can contain additional polymer. In one embodiment the waste label material includes at least a part of poly^¬ mer needed in the coating composition.

In one embodiment the waste label material contains adhesive material onto which a layer of glue has been provided, and fitted onto the layer of glue as a protective sheet is release material that can be easily released at the application site of the stick- er. In one preferred embodiment, the adhesive material and/or release material contains a wood fiber based com^¬ ponent and/or a plastic or polymer based or other organic component. Also, the use of different inorganic mate^¬ rials is possible. In one embodiment, the adhesive and/or release material encompasses wood fiber based pa^¬ per, paperboard or the like. In one embodiment, the wood fiber based paper, paperboard or the like contains or is treated with plastic or polymer based material. In one embodiment, the adhesive and/or release material may be formed from substantially plastic or polymer based mate^¬ rial. In one embodiment, the release material is formed mainly from plastic based material, containing e.g. pol^¬ ypropylene, polyethylene, polyethylene terephthalate or their mixtures. In one embodiment, the release material contains a silicone based component, such as siliconized material, e.g. siliconized film material. In one embodi^¬ ment, the release material is coated with silicone based material or compound.

In one embodiment, finished label material products, waste material produced by them and/or in their manufacture may be used as waste label material in the coating composition. In addition, waste material from production and recycling material from the upgrading stage or end use applications of label mate- rial products may be used. In one embodiment, the waste label material comes from label material produc^¬ tion which produces mainly production reject waste, edge trimming waste cut off from rolls, and roll ends; from the label material printing plant which produces mainly roll ends and label material left over from die-cutting of stickers and labels, as well as reject waste; and/or from the label material end user custo^¬ mer who pastes the printed stickers and labels or the like on products. The waste coming from the end user encompasses mainly release material, roll ends and waste from the finished product. In one embodiment, the waste label material may contain a variable amount of different waste label material components, such as adhesive material, glue and release material. In one embodiment, the fibres of the waste label material have been covered by polymer in the coating composition.

In one embodiment the coating composition contains other material, such as metal, e.g. aluminum, fiber material or their combinations or the like.

In one embodiment the coating composition contains at least one additive selected from the group: compatibilizing agent, colour dyes, biocides, fire retardants, water repellents, dimensional stabilisers, pigments, nanoparticles , bio-resistant agents, florescent particles, fatty acids, modified fatty acids, oils, densification resins, emulsions, hardeners, UV protectors, UV stabilisers fibers, reinforcement fibers, other wood modification agent and their combinations. It is important to select additives so that they will not deactivate the coupling agent.

In one embodiment the coating composition with the coupling agent is a self-adhesive material which adheres on the surface of the material article and which glues the material articles together.

In one embodiment the coating composition is in the form melt, liquid, suspension, solid or the like. In one embodiment the coating composition is in the form of a film. Preferably, the coating composition containing polymer and coupling agent can be injected or extruded directly into the mould.

In one embodiment the coating formed of the coating composition by the injection moulding comprises at least one layer. The coating on the material article can consist of one or more layers where at least one layer contains coupling agent. The compositions of the different layers can be varied. For example, the middle layer in the coating can be any suitable material and it can be printed on or even function as a decorative layer. RFID, sensors or barcode indicators, and reinforcement fiber material can also be incorporated into the coating.

In this context, a coating refers to any coating layer or the like which is formed by the injection moulding to encapsulate the material article.

In one embodiment the coating composition is in the form of a film. In one embodiment the film contains more than one film layer.

In one embodiment the coating composition is a film formed of polyolefin - coupling agent composition containing reactive groups which are reactive with reactive groups of the material article, e.g. with -OH groups of the wood, for forming bonds via esterification between the material article and the film. In one embodiment the coating composition is a self-adhesive polyolefin film modified maleic anhydride. In one embodiment the film can comprise more than one layer, e.g. two or three layers where the outer layers contain maleic anhydride grafted polyethylene or polypropylene. In one embodiment the film is the self-adhesive polyolefin film, as defined in patent applications PCT/FI2009/050130 and PCT/FI2009/050662. In one embodiment the film is used to create the product that has strength properties and fibre breakage percentage that exceeds that of phenol formaldehyde bonded product. In the injection moulding according to the invention there can be used any injection moulding and/or encapsulation method. In one embodiment of the invention the coating composition is provided in the mould by injection or extrusion and the material article is encapsulated by the means for the injection moulding .

In one embodiment of the invention the coupling agent is activated by means of the heat, catalyst or their combinations. In one embodiment the coupling agent is activated to its active state by means of the heat. In one embodiment the coupling agent is activated to its active state by means of the catalyst. In one embodiment the coupling agent is activated to its active state by means of the heat and catalyst .

In one embodiment the coupling agent is activated at temperatures of more than 190 °C. In one embodiment of the invention the coupling agent is activated at temperature between 190 to 240 °C. After the activation the coupling agent is reactive with reactive groups of the material article.

In one embodiment of the invention the activation of the coupling agent is prepared by a catalyst so that the coupling agent is activated by means of a catalyst. The activation can be made with or without a catalyst. In one embodiment the catalyst is selected from the group: zinc anhydride, hydrated zinc acetate, zinc acetate dehydrate and their derivatives, sodium hypophosphite monohydrate (SHP) , sodium hypophosphite (NaH₂P0₂) , sodium phosphate (NaH₂P0₄) , sodium phosphinate monohydrate (NaH₂P0₂ H₂0) , potassium phosphate, ammonium phosphate, titanium dioxide and their combinations. The invention is not limited to these catalysts only, they are only examples .

In one embodiment of the invention the coupling agent is activated during the injection moulding. In one embodiment the coupling agent is activated before the injection moulding.

In one embodiment the coating composition is heated during or before the injection moulding. In one embodiment the material article is heated before the injection moulding. In one embodiment the material article, especially the surface of the material article, is heated just before the contact of the material article with the coating composition in order to remove moisture from the material article. Then the coating composition adheres better on the material article .

In one embodiment the polymer of the coating composition is cross-linked. In one embodiment the cross-linking is carried out before the injection moulding. In one embodiment the cross-linking is carried out during the injection moulding. In one embodiment the cross-linking is carried out after the injection moulding. It is also possible to add silane grafted polyethylene and radiation sensitive grade polyethylene in order to cross-link the polymer. These materials are commercially available. In the case of silane versions a catalyst master batch is also required. In the case of radiation treatment of the coating composition on the material article the cross- linking can be performed by microwave, electron-beam, Gamma and UV treatment. However, in one case of cross- linking much deeper penetration is required. The depth of penetration of E-beam, Gamma and X-ray also mean that any material article that are impregnated with any material modification treatments can be cured also by these treatments at the same time as cross-linking the polymers in the material article. For material article that is not more than, for example, 20 mm thick an E-beam is sufficient. However, in the case of thicker materials, e.g. between 20 - 117 mm, X-ray treatment can be applied. Both E-beam and X-ray treatment don't require the polymer to be heated during treatment. Both Gamma and E-beam treatment can damage the wood strength properties; however, this is not the case with X-ray treatment. For example, with X-ray treatment it is possible to cure to depths of 240 mm, depending on the density, at energies of only 3 MeV and low dose rate 2 kGy/min.

Also the material article can be impregnated with chemicals that can then be cured, e.g. cross- linked or polymerized, while cross-linking the other materials in the material article. The impregnated materials can be dyes, fire retardants, biocides, dimensional stabilizing chemicals and wood densifying chemicals or the like. Also, wood plasticisers , e.g. monomers and polyethylene glycol, can be impregnated to give the wood a more plastic nature.

While the coupling agent chemically bonds with the wood it is important for the polymer to sufficiently wet the wood so it can intimately be in contact to increase the frequency of the chemical bond. However, modification of the polymer by corona treatment or flame, plasma or ozone treatment can further increase the surface energies of the polymer. This treatment is possible during the injection moulding process. In addition to these treatments another on-line modification is ozone treatment.

In one embodiment the material article is dried before the injection moulding. The moisture content affects greatly on penetration of the polymer into the material.

In one embodiment of the invention the moisture content of the material article is kept below 10 % during the injection moulding. In one embodiment the moisture content of the material article is kept below 5 % during the injection moulding. Then the injected molten polymer of the coating composition can intimately contact the material article. Further, the coupling agent is not deactivated.

In one embodiment of the invention the material article is pre-coated with any suitable coating material, and the pre-coated material article is encapsulated with the coating composition according to the invention as defined above. In one embodiment the material article is pre-coated by a film coating or an extrusion coating. In one embodiment the material article is pre-coated with the coating composition according to the invention. In one embodiment the pre-coating provides a surface of the material article to which the coating composition according to the invention is easy to bond.

In one embodiment the material article is pre-coated by at least one material layer before the injection moulding. The material layer can contain any material, e.g. textile (woven and nonwoven) , paper, metal, porous material or their combinations or the like. Creating a composite layered coating of varying properties is advantageous.

In one embodiment the material article is formable on reheating and can be cross-linked to render the glue-line with viscoelastic like properties .

In the case where the material article is formable the material article can be reheated in an oven or microwave or via high-frequency. Pressure is not required during the re-heating but it is desired that the material article is formed under pressure and cooled in order not to damage the bonds formed during the initial hot-pressing. It is found that reheating and pressing actually improves on the bonding quality. If a microwave is used to reheat the material article then the polymer needs to be able to absorb microwaves. Most polymers do not absorb microwaves to a sufficient extent to be heated. Polymers have very low dielectric properties and therefore can be improved by the addition of fillers e.g. zinc oxide, carbon black, talc, glass, ceramic, EVA, MAPP and MAPE . The invention is not limited to these materials only. The reheating and shaping of the formable material article can be made before, during or after the injection moulding. The material article can be formed into shape first and the formable material article is utilized as a reinforced insert in the liquid injection moulding.

In one embodiment the material article can be cross-linked before moulding into shape, in order to take advantage of the viscoelastic or elastomer properties. Cross-linked polyethylene, above it's crystalline melting point, can be stretched a lot more than its uncross-linked version.

The injection moulded product can be made using apparatuses and methods known per se. Typical steps for making the injection moulded product can be performed in any manner known per se in the art. The coating composition can be formed in the plasticization unit of the injection moulding apparatus and can be injected or extruded into the mould .

In one embodiment the coating composition is injected or extruded into a mould. In one embodiment the material article is placed into the mould. In one embodiment the coating composition is injected or extruded into a mould and the material article is placed into the mould and the material article is encapsulated with the coating composition. In one embodiment the material article is placed into the mould and the coating composition is injected or extruded onto the material article and the material article is encapsulated with the coating composition. In one embodiment the coating composition is injected or extruded into the mould and the material article is placed into the mould and the coating composition is injected or extruded onto the material article in order to encapsulate the material article with the coating composition.

An advantage of the invention is to provide more highly weather and water resistant and strong products which are also decorative and light if desired .

Thanks to the invention it can be produced injection moulded products having thermoplastic and/or formable composition that can also be cross-linked.

By means of the method of the invention the molten coating composition can applied on the material directly during the injection moulding, e.g. from an extruded. The injection moulding with the molten coating composition eliminates the need to manufacture the coating material separate.

The method and injection moulded product in accordance with the invention are suitable for various applications. The material articles of the invention can be used to form wet resistance products, dimensionally stable products, furniture, children's furniture and kitchens and the like. In addition to this the material article and the injection moulded product can be utilised in the transport and ship building industries, automotive, construction including scaffolding, in technically challenging parts, e.g. wind mills, musical instruments and sound insulated wood board for buildings and stairs, side walls and floors of vans, trailers, trains, coaches, vans lorries and horse boxes, play ground equipment, sports equipment, flight cases, sign boards, die boards, rotary die boards, DIY applications and yachts. However, the invention is not limited to these examples only.

The self-adhesive coating composition in accordance with the invention is suitable for bonding other additional material with material article to create various composite materials.

LIST OF FIGURES

In the following, the invention is described by means of detailed embodiment example with reference to accompanying figures 1 - 3, in which

Fig. 1 shows a schedule of a method according to the invention, Fig. 2 shows a reaction of conversion of maleic acid to maleic anhydride and its reaction with wood hydroxide groups in the coating, and

Fig. 3 shows a reaction of conversion of maleic acid to maleic anhydride and its reaction with wood hydroxide groups in the wood board manufacturing.

DETAILED DESCRIPTION OF THE INVENTION Example 1

In this example, an injection moulded product is manufactured by the method of the invention. In figure 1 it is shown a process for manufacturing the injection moulded product from material article inserts.

The first step 1 is a selection of the raw materials, such as la) material article inserts from e.g. veneer, plywood, other boards, paper, paper board, natural materials, cellulose or metal; and lb) coating composition, e.g. polymers, thermoplastics, recycled material, e.g. label waste, and coupling agent, e.g. maleated polymer; and lc) possible additives and other materials. The maleated material of the polymer is conversed from maleic acid to maleic anhydride.

The second step 2 is a preparation of inserts. The inserts can be pre-treated or pre-coated before the injection moulding. The inserts can be also formed into desired shape.

The third step 3 is an injection moulding in which the coating composition is extruded into moulds and the inserts are placed into the moulds. The coupling agent is activated in connection with the injection moulding by utilising heat with or without a catalyst. The examples of conversion reactions and bonding reactions between maleic anhydride and the wood hydroxide groups are shown in figures 2 and 3. The active maleic anhydride groups react with the hydroxide groups of the wood to form an ester bond. The inserts are completely encapsulated in the coating composition .

The plywood or product from the injection moulding 3 can be reheated and moulded into shape 5 and/or cross-linked or cured 6. The injection moulded product which is water resistant is delivered to customer 4.

Example 2

In this example, an injection moulded product is manufactured from the plywood inserts by the injection moulding.

The plywood, e.g. phenolic bonded or thermoplastic bonded, including films and extrusion coated, and formable plywood, e.g. thermoplastic bonded, including films and extrusion coated, are placed as inserts into moulds manually or by robots. The plywood behaves as a flat or formable reinforced insert. It is important that there is excellent interaction between the injected polymer and the plywood insert and therefore either the plywood insert should be coated (inject coated or film coated) or maleated coupling agent should be added to the extruder and melted with the injection polymer. The injection moulding temperatures is sufficient to convert the coupling agent, but a catalyst can also be utilised .

The formable plywood can be used as a flat insert in the injection moulding and then after cooling it can be formed into various shapes. Alternatively, the plywood can be formed into shape first and the formable plywood utilised as a reinforced insert in the liquid injection moulding. Once the plywood is made it can on heating be formed into various shapes and then used or it can be loaded into a mould manually or by robots and polymer can be injected at high speed.

Plywood and formable plywood have better dimensional stability than solid wood; however, the dimensional stability is still not sufficient and very often the plywood warps and twists. By covering the plywood and formable plywood insert with polymer it will create a composite plastic product with a protective coating capable of preventing the penetration of moisture. One of the advantages of injection moulding is that the plywood will be some distance from the surface and therefore be more resistant to moisture.

Polypropylene, polyethylene, their combinations and also other injection mouldable polymers, e.g. PA, PET, polystyrene, polycarbonates, vinyl plastics, acrylics and cellulosics, can be utilised. Also foamable thermoplastics can be used and therefore a blowing agent must be extruded with the thermoplastic. The polymer needs to be injected into the mould at temperatures above the activation temperature of the blowing agent. Also, in addition to the above it is possible to cross-link the polymers by radiation treatment cross-linking and in the case of polyethylene also silane cross-linking. The cross- linked version will be heat resistant and wear resistant and resistant to greater impact.

Example 3

In this example, an injection moulded product was manufactured from the veneer inserts by the injection moulding.

First coating compositions, as defined in table 1, were formed and extruded into moulds. The veneers, as defined in table 1, were placed as inserts into the moulds. A part of the veneers included adhesive and/or pre-coating.

Table 1

Samples Material article Coating

composition

1 - 4 0.6 mm birch veneer PP, PP+MAPP, Label

(uncoated) waste+MAPP,

HDPE+MAPE

5 - 6 1.5 mm birch and spruce Label waste+MAPP veneers (uncoated)

7 2.6 mm spruce veneer Label waste+MAPP

(uncoated)

8 - 11 0.6 mm birch veneer PP, PP+MAPP, Label

( coated) waste+MAPP,

HDPE+MAPE

12 - 14 3-ply uncoated PP+MAPP, Label waste+MAPP,

HDPE+MAPE

15 - 17 3-ply coated PP, PP+MAPP, Label waste+MAPP,

HDPE+MAPE

In these experiments, PP means polypropylene, MAPP means maleic anhydride + polypropylene, HDPE means high density polyethylene, MAPE means maleic anhydride + polyethylene, 3-ply birch means plywood with 3 veneer layers and label waste means waste label material containing adhesive material onto which a layer of glue has been provided, and fitted onto the layer of glue as a protective sheet is release material that can be easily released at the application site of the sticker.

In these experiments there were used dry veneers. Plywood used was formed of dried veneers. The veneers were dried by microwave.

The veneers inserts were encapsulated partly or wholly with the coating composition in the injection moulding process.

From the experiments it was discovered that adhesion between the coating composition and the veneer inserts was very good. The results showed that the injected moulded polymers were bonded very well to the veneers and plywood. The use of a coupling agent improved especially properties in long-term outdoor applications. The hardness and scratch resistance of the sample was directly related to the injection polymer .

Further, it was discovered that the use of the label waste produced new and good properties for the final product. The use of the label waste improved flatness in the final product and decreased warpage of the final product. It was discovered that also the coating only one surface was enough to keep above- mentioned properties.

Further, from the experiments it was discovered that a method of the invention was suitable to be used for an injection moulding and for encapsulating different material articles with the coating composition easily and cost effectively. By the invention products with weather, water, impact and vandalism proof could be manufactured.

Methods for encapsulating the material article with the coating composition and for manufacturing the injection moulded product according to the invention are suitable in their different embodiments for different types of applications.

The embodiments of the invention are not limited to the examples presented rather many variations are possible within the scope of the accompanying claims .

Claims

1. A method for coating a material article with a coating composition, c h a r a c t e r i z e d in that the material article is encapsulated by a injec- tion moulding and the material article is encapsulated with the coating composition, the coating composition contains at least one polymer and a coupling agent having reactive groups with the material article, and the coupling agent is activated to its active state in connection with the injection moulding to form chemical bonds between the material article and the cou^¬ pling agent.

2. The method according to claim 1, c h a r a c t e r i z e d in that the coupling agent is acti- vated by means of the heat, catalyst or their combina^¬ tions .

3. The method according to claim 1 or 2, c h a r a c t e r i z e d in that the coupling agent is activated at temperature between 190 to 240 °C.

4. The method according to any one of claims

1 to 3, c h a r a c t e r i z e d in that the coupling agent is activated during the injection moulding.

5. The method according to any one of claims 1 to 4, c h a r a c t e r i z e d in that the coupling agent is activated before the injection moulding.

6. The method according to any one of claims 1 to 5, c h a r a c t e r i z e d in that the coupling agent is reactive with -OH groups of the material ar^¬ ticle .

7. The method according to any one of claims

1 to 6, c h a r a c t e r i z e d in that the material article is encapsulated by coating at least one sur^¬ face of the material article with the coating composi^¬ tion.

8. The method according to any one of claims

1 to 7, c h a r a c t e r i z e d in that the material article is encapsulated in whole by the coating compo^¬ sition.

9. The method according to any one of claims 1 to 8, c h a r a c t e r i z e d in that the moisture content of the material article is kept below 10 %.

10. The method according to any one of claims 1 to 9, c h a r a c t e r i z e d in that the moisture content of the material article is kept below 5 %.

11. The method according to any one of claims 1 to 10, c h a r a c t e r i z e d in that the coupling agent is maleic anhydride.

12. The method according to any one of claims 1 to 11, c h a r a c t e r i z e d in that the coating composition contains recycled material.

13. The method according to any one of claims

1 to 12, c h a r a c t e r i z e d in that the material article consists of at least one insert.

14. The method according to any one of claims 1 to 13, c h a r a c t e r i z e d in that the material of the material article is chosen from the group: nat^¬ ural based material, wood, wood based material, cellu^¬ lose based material, plastic, plastic based material, metal, composite material and their combinations.

15. The method according to any one of claims 1 to 14, c h a r a c t e r i z e d in that the material article is chosen from the group: a veneer, a board, a layered structure, a wood article, a wood-based arti^¬ cle, a composite article, a formable product, a fiber product and their combinations.

16. A method for manufacturing an injection moulded product, wherein a material article is coated with a coating composition, c h a r a c t e r i z e d in that the material article is encapsulated by the in^¬ jection moulding and the material article is encapsu- lated with the coating composition containing at least one polymer and a coupling agent which has reactive groups being reactive with the material article, and the coupling agent is activated to its active state in connection with the injection moulding to form chemical bonds between the material article and the cou^¬ pling agent in order to form the injection moulded product .

17. The method according to claim 16, c h a r a c t e r i z e d in that the coating composi^¬ tion is injected into a mould.

18. The method according to claim 16 or 17, c h a r a c t e r i z e d in that the material article is placed into the mould.

19. The method according to any one of claims 16 to 18, c h a r a c t e r i z e d in that the material article is provided as inserts into the mould.

20. The method according to any one of claims

16 to 19, c h a r a c t e r i z e d in that the coupling agent is activated by means of the heat, catalyst or their combinations.

21. The method according to any one of claims 16 to 20, c h a r a c t e r i z e d in that the material article is pre-coated before forming the injection moulded product .

22. The method according to any one of claims 16 to 21, c h a r a c t e r i z e d in that the moisture content of the material article has been kept below 10 % during the manufacturing of the injection moulded product .

23. The method according to any one of claims 16 to 22, c h a r a c t e r i z e d in that the material article is encapsulated by coating at least one sur^¬ face of the material article with the coating composi^¬ tion.

24. The method according to any one of claims 16 to 23, c h a r a c t e r i z e d in that the material article is encapsulated in whole by the coating compo^¬ sition.

25. An injection moulded product, which is formed by an injection moulding and is coated with a coating composition, c h a r a c t e r i z e d in that the material article is encapsulated with the coating composition containing at least one polymer and a coupling agent which has reactive groups being reactive with the material article, and the chemical bonds are formed between the coupling agent and the material ar^¬ ticle in order to form the injection moulded product.