WO2021258126A1

WO2021258126A1 - Method of treating a surface

Info

Publication number: WO2021258126A1
Application number: PCT/AU2020/050650
Authority: WO
Inventors: Graham Charles Stevens
Original assignee: St. Vens Pty Ltd
Priority date: 2020-06-26
Filing date: 2020-06-26
Publication date: 2021-12-30

Abstract

A method of treating a surface of a polymer or polymer composite object, the method comprising the steps of: ionising bonding portions of said object; and applying a coating of haloform (CHX₃) or a derivative thereof to said ionised bonding portions, wherein X is a halogen.

Description

METHOD OF TREATING A SURFACE

TECHNICAL FIELD

[001] The present invention relates to a method of treating a surface of a polymer, polyolefin or polyolefin composite object. The present invention also relates to a coated polyolefin or polyolefin composite object.

BACKGROUND

[002] Any references to methods, apparatus or documents of the prior art are not to be taken as constituting any evidence or admission that they formed, or form part of the common general knowledge.

[003] Polymers, such as polyolefins, polyethylene, polypropylene and nylon, have become a preferred material for formed parts used in a variety of assembled products due to their balance of properties, ease of fabrication due to their thermoplastic nature, relatively low cost and formulation technology which allows tailoring of their properties for certain uses. Polyolefins are used in a wide variety of industries such as automotive, furniture, electronics, toys, appliances and the like. The drawback with the use of polyolefins in assemblies of different materials is that polyolefins have low polarity on their surfaces which means that the coatings and adhesives preferred for use in industry based on polyisocyanate functional resins (polyurethanes) do not easily bond to polyolefins. In order to bond such materials to polyolefins, the polyolefin surface needs to be modified. It is well known to modify the surface of polyolefin parts to enhance adhesion to adhesives with polar groups. This is achieved typically by flame treatment, corona discharge treatment, etching physically or with chemicals or through the use of primers. Each of these treatments have limitation in commercial application due to the speed of application, excessive distortion of polyolefin objects or simply limited surface energy in the case of primer.

[004] Low energy polyolefin surfaces have limited the more extensive use of polyolefins and polyolefin composite products in industry where printing, painting and fixings such as adhesives and sealants, has been required. [005] Low surface energy of any substrate greatly reduces the bonding ability of inks, paints, adhesives, sealants or any other product requiring high energy surface bonding. Modification of the substrate surface energy to an increased surface energy level is a practical method allowing the broader use of polyolefin and polyolefin composite use throughout all industry sectors.

[006] Components or parts prepared from polyolefins are often manufactured by component suppliers that sell and ship the components and parts to an original equipment manufacturer. Such equipment manufacturers then utilise the components for assembling equipment and final assemblies. It is desirable for the equipment manufacturer to receive components that are ready for use such that the components can be used for assembly with minimal treatment or modification. The currently known methods for surface modification require manufacturers to modify the surface of a polyolefin object in their plant during or just before assembly, and this can add to the complexity of manufacturing equipment. Therefore, it is desirable to provide a surface modification method. It is also important to provide a surface modification method to allow for modification in a plant remote in time and place from the ultimate assembly plant. In this regard, it would be desirable to provide a surface modification method that allows the modified surface to retain its ability to bond to coatings or sealants for at least long durations of time to allow the modified surfaces to bond when components are shipped to a different location for assembly.

[007] It should be apparent that there is a need to alleviate one or more of the above issues, or to at least provide the consumer with a commercial alternative.

BRIEF DESCRIPTION OF THE DRAWINGS

[008] To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect, preferred embodiments of the invention will be described by way of example only with reference to the accompanying drawings, in which:

FIG 1 shows a photograph of the results of the lap shear test for Sample 1 ;

FIG 2 shows a photograph of the results of the lap shear test for Sample 2;

FIG 3 shows a photograph of the results of the lap shear test for Sample 3;

FIG 4 shows a photograph of the results of the lap shear test for Sample 4; FIG 5 shows a photograph of the results of the lap shear test for Sample 5; and FIG 6 shows a photograph of the results of the lap shear test for Sample 6;

SUMMARY OF INVENTION

[009] In an aspect, the invention provides a method of treating a surface of a polymer or polymer composite object, the method comprising the steps of: ionising bonding portions of said object; and applying a haloform CHX₃ or a derivative thereof to said bonding portions, wherein X is a halogen.

[010] In one embodiment, the haloform may be in the form of chloroform, bromoform, fluoroform or iodoform. In one embodiment, the haloform is in the form of a solvent or liquid.

[011] In an embodiment, the method comprises the step of applying the haloform solvent is undertaken within a pre-determined time period after the ionising step.

[012] The pre-determined time period is suitably no more than 1 hour, more suitable less than 30 minutes, preferably less than 20 minutes, more preferably less than 15 minutes and still more preferably less than 5 minutes. The time period may be in the range of 15 minutes to 30 minutes or 10 minutes to 20 minutes. In one embodiment, the pre-determined time period is immediately after ionizing.

[013] In an embodiment, the step of applying the haloform comprises one or more of the following: spraying, misting, rolling, wiping the haloform solvent on the bonding portions.

[014] In one embodiment, the polymer is polyolefin and the polymer composite object is a polyolefin composite object.

[015] In one embodiment, the ionising is achieved by irradiating the bonding portions with electromagnetic radiation. [016] In one embodiment, the invention resides in a method of treating a surface of a polymer or polymer composite object, the method comprising the steps of: irradiating bonding portions of said object with electromagnetic radiation; and applying a haloform CHX₃ or a derivative thereof to said bonding portions, wherein X is a halogen

[017] In an embodiment, the electromagnetic radiation is infrared radiation, microwave radiation, x-ray radiation, ultraviolet radiation and/or gamma radiation. In one embodiment, the electromagnetic radiation is infrared radiation, microwave radiation and/or infrared radiation. In one embodiment, the electromagnetic radiation is infrared radiation and/or microwave radiation.

[018] In an embodiment, the irradiating step comprises irradiating the bonding portions with ultraviolet radiation. In one embodiment, the irradiating step comprises irradiating the bonding portions with microwave radiation. In some embodiments, the irradiating step comprises irradiating the bonding portions with ultraviolet radiation. In embodiments, the irradiating step comprises irradiating the bonding portions with infrared radiation.

[019] In an embodiment, the microwave radiation source comprises a microwave oven. In one embodiment, the infrared radiation source is an infrared globe or lamp.

[020] In an embodiment, the method further includes the step of irradiating said bonding portions with ultraviolet radiation. In one embodiment, the ultraviolet radiation source is an ultraviolet radiation globe or lamp.

[021] In another aspect, the invention comprises a method of bonding a polymer object with a surface, the method comprising the steps of: ionising bonding portions of said polymer object; and applying haloform CHX₃ or a derivative thereof to said bonding portions of the polymer object to form modified bonding portions, wherein X is a halogen; applying one or more adhesives to the modified bonding portions of the polymer object to bond the modified bonding portions of the polymer object; and bonding said bonding portions of the polymer object with the surface. [022] In one embodiment, the surface is selected from the group consisting of metallic surface, metallic mesh, fabric or mat of polymer or polyethylene or polyethylene amide origin. In one embodiment, the surface is a metallic surface

[023] In one embodiment, the polymer object is a polyolefin object.

[024] In one embodiment, the ionising is achieved by irradiating the bonding portions with electromagnetic radiation.

[025] In an embodiment, the invention resides in a method of bonding a polymer object with a surface, the method comprising the steps of: irradiating bonding portions of said polymer object with electromagnetic irradiation; and applying haloform CHX₃ or a derivative thereof to said bonding portions of the polymer object to form modified bonding portions, wherein X is a halogen; applying one or more adhesives to the modified bonding portions of the polymer object to bond the modified bonding portions of the polymer object; and bonding said bonding portions of the polymer object with the surface, wherein the surface is selected from the group consisting of metallic surface metallic mesh, fabric or mat of polymer or polyethylene or polyethylene amide origin.

[026] In one embodiment, the polymer object is a polyolefin object.

[027] In an embodiment, the electromagnetic radiation is infrared radiation, microwave radiation, x-ray radiation, ultraviolet radiation and/or gamma radiation. In one embodiment, the electromagnetic radiation is infrared radiation, microwave radiation and/or infrared radiation. In one embodiment, the electromagnetic radiation is infrared radiation and/or microwave radiation.

[028] In an embodiment, the irradiating step comprises irradiating the bonding portions with ultraviolet radiation. In one embodiment, the irradiating step comprises irradiating the bonding portions with microwave radiation. In some embodiments, the irradiating step comprises irradiating the bonding portions with ultraviolet radiation. In embodiments, the irradiating step comprises irradiating the bonding portions with infrared radiation.

[029] In an embodiment, the polymer object is a polyolefin object.

[030] In one embodiment, the method further includes the step of irradiating said bonding portions using ultraviolet radiation.

[031] In yet another aspect, the invention provides a method of treating a surface of a polymer object, the method comprising the steps of: ionising bonding portions of said polymer object; and applying a halogenated solvent or a derivative thereof to said bonding portions.

[032] In some embodiment, the ionising is achieved by irradiating the bonding portions with electromagnetic radiation.

[033] In one embodiment, the method further includes the step of irradiating said bonding portions using ultraviolet radiation.

[034] In an embodiment, the polymer object is a polyolefin object.

[035] In one embodiment, the ionising is achieved by irradiating the bonding portions with electromagnetic radiation.

[036] In one embodiment, the invention provides a method of treating a surface of a polymer object, the method comprising the steps of: irradiating bonding portions said polymer object with electromagnetic radiation; and applying a halogenated solvent or a derivative thereof to said bonding portions of the polymer object.

[037] In one embodiment, the polymer object is a polyolefin object. [038] In an embodiment, the electromagnetic radiation is infrared radiation, microwave radiation, x-ray radiation, ultraviolet radiation and/or gamma radiation. In one embodiment, the electromagnetic radiation is infrared radiation, microwave radiation and/or infrared radiation. In one embodiment, the electromagnetic radiation is infrared radiation and/or microwave radiation.

[039] In an embodiment, the irradiating step comprises irradiating the bonding portions with ultraviolet radiation. In one embodiment, the irradiating step comprises irradiating the bonding portions with microwave radiation. In some embodiments, the irradiating step comprises irradiating the bonding portions with ultraviolet radiation. In embodiments, the irradiating step comprises irradiating the bonding portions with infrared radiation.

[040] In one embodiment, the method further includes the step of irradiating said bonding portions using ultraviolet radiation.

[041] In another aspect, the invention comprises a method of forming a polymer object with at least one bonding surface, the method comprising the steps of: preparing a resinous biend comprising a low surface energy polymer; transferring the resinous blend to an extrusion apparatus; extruding the resinous blend via the extrusion apparatus to form the extruded polymer object; ionising bonding portions of said extruded polymer object; and applying a haloform CHX₃ or a derivative thereof to said bonding portions, wherein X is a halogen.

[042] In one embodiment, the polymer is polyolefin.

[043] In some embodiment, the ionising is achieved by irradiating the bonding portions with electromagnetic radiation.

[044] In one embodiment, the method further includes the step of irradiating said bonding portions using ultraviolet radiation. [045] In an embodiment, the invention comprises a method of forming a polymer object with at least one bonding surface, the method comprising the steps of: preparing a resinous blend comprising a low surface energy polymer; transferring the resinous blend to an extrusion apparatus; extruding the resinous blend via the extrusion apparatus to form the extruded polymer object; irradiating bonding portions of said extruded polymer object with electromagnetic radiation; and applying a haloform CHX₃ or a derivative thereof to said bonding portions of the polyolefin object, wherein X is a halogen.

[046] In some embodiments, the polymer object is a polyolefin object.

[047] In one embodiment, the method further includes the step of irradiating said bonding portions using ultraviolet radiation.

[048] In an embodiment, the electromagnetic radiation is infrared radiation, microwave radiation, x-ray radiation, ultraviolet radiation and/or gamma radiation. In one embodiment, the electromagnetic radiation is infrared radiation, microwave radiation and/or infrared radiation. In one embodiment, the electromagnetic radiation is infrared radiation and/or microwave radiation.

[049] In another aspect, the invention provides a polymer object or a polymer composite object adapted for being adhesively bonded, the object comprising: a bulk volume comprising a low surface energy polymer; an outer surface having one or more bonding regions comprising ionised modified molecular surface wherein the modified molecular surface comprises a coating of a haloform CHX₃ or a derivative thereof, wherein X is a halogen.

[050] In some embodiments, the polymer object is a polyolefin object and the polymer composite object is a polyolefin object.

[051] In one embodiment, the method further includes the step of irradiating said bonding portions using ultraviolet radiation. [052] In some embodiment, the electromagnetic radiation is infrared radiation, microwave radiation, x-ray radiation, ultraviolet radiation and/or gamma radiation. In one embodiment, the electromagnetic radiation is infrared radiation, microwave radiation and/or infrared radiation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[053] Embodiment of the present invention relate to the modification of polymer structures, parts or components, used in assemblies to enhance the bonding of polar adhesives to one or more surfaces of the polymer structures. Disclosed herein are method or processes for either modifying polymer articles or manufacturing polymer articles having one or more surfaces modified according to the methods described herein.

[054] As used herein, the term ‘irradiating’ refers to exposing a substance or object to radiation. In this regard, ‘irradiating’ may be considered energizing where the substance or object is energized by exposing the substance or object to radiation. [055] As used herein, the term ‘polymer’ refers to a chemical structure that comprises long repeating chains of monomers. A non-limiting example of a polymer is polyolefin. As used herein, the term ‘polymer’ may be interchangeable with the term ‘polyolefin’.

[056] The initial stage of an exemplary method embodiment of the present invention involves ionizing a surface of the polymer/polymer composite object using a suitable electromagnetic radiation source sufficient to irradiate and modify said polymer surface. One method for treating the surface of the polymer/polymer composite object may include exposure to high energy Ultra Violet light. Most commercial sources of ultraviolet radiation can be used in the process of the present invention, although the preferred source consists of a quartz-jacketed mercury vapor lamp. For the purposes of this invention the term "ultraviolet radiation" is intended to mean all that radiation emitted by the ultraviolet source within the wavelength range of 187-400 nm. It is important to control the amount of such ultraviolet radiation used because too little radiation may not adequately exchange the exposed surface while excessive ultraviolet radiation may cause degradation of the exposed surface and again harm paint adhesion. [057] The step of irradiation of the polymer surface molecules by electromagnetic radiation results in increased surface energy of the polymer surface exposed to such radiation. In an embodiment, the electromagnetic radiation is infrared radiation, microwave radiation, x-ray radiation, ultraviolet radiation and/or gamma radiation. In one embodiment, the electromagnetic radiation is infrared radiation, microwave radiation and/or infrared radiation. In one embodiment, the electromagnetic radiation is infrared radiation and/or microwave radiation. Such an increase in surface energy is somewhat relatively short-lived. However, the next step of the exemplary method involves application of a haloform (such as but not limited to a chloroform or a bromoform solution) solution on the irradiated portions of the surface of the polyolefin object. This haloform treatment step may be followed by treatment with ultraviolet radiation to facilitate increased molecular exchange on the bonding portions. Without being bound by theory, it is hypothesized that application of the haloform solution or any other halogenated compound or a derivative thereof to the bonding surface of the polymer object with an increased surface energy (as a result of the initial step) results in a less compact molecular structure on the exposed regions of the polymer surface which facilitates molecular exchange on the surface. This is particular the case when exposed to ultraviolet radiation which surprisingly improves the adhesion characteristics of the treated surface. The results suggest that the improved adhesion characteristics after treatment with the haloform solution are not short-lived. Furthermore, the results suggest that the improved adhesion characteristics after treatment including the step of irradiation with ultraviolet radiation also are not shortlived. In one embodiment, the UV radiation source is a UV lamp or UV globe. In one embodiment the UV radiation source are provided by Australian Ultra Violet Services Pty Ltd (GL021 G48T15H 2 PIN UV LAMP (OZONE PRODUCING))

[058] One method of treating the surface of the polymer/polymer composite objection may include exposure to infrared radiation. Most commercial sources of infrared radiation can be used in the process of the present invention. For the purposes of this invention, the term “infrared radiation” is intended to mean all radiation emitted by an infrared radiation source within the wavelength range of 700nm to 1mm. It is important to control the amount of such infrared radiation utilized as too little radiation may not adequate exchange the exposed surface while excessive infrared radiation may cause degradation. In one embodiment, the infrared radiation source is an infrared globe. The filament temperature of the infrared globe is suitably from 800°C to 900°C. The peak wavelength of the infrared globe is suitable from 2.4 to 2.7 pm. Maximum current of the infrared globe is suitable 8/10/20/A. Mean power density of the infrared globe is 50kW/m. The above specifications of the infrared globe relate to a medium wavelength infrared globe from Infralight Australia. The person skilled in the art will appreciate that other infrared light globes and sources can be utilized with the present invention.

[059] One method of treating the surface of the polymer/polymer composite objection may include exposure to microwave radiation. Most commercial sources of microwave radiation can be used in the process of the present invention. For the purposes of this invention, the term “microwave radiation” is intended to mean all radiation emitted by an microwave radiation source within the wavelength range of 1mm to 1m. It is important to control the amount of such microwave radiation utilized as too little radiation may not adequate exchange the exposed surface while excessive microwave radiation may cause degradation.

[060] The treatment period utilizing electromagnetic radiation is suitably at least about 5 minutes, more suitably at least about 6 minutes, even more suitably at least about 7 minutes, preferably at least about 10 minutes, more preferably at least about 20 minutes and most preferably at least about 30 minutes. It will be appreciated that, longer times may be utilized. The timeframe will be dependent on the thickness of the substrate. In one embodiment, the treatment period is about 6 minutes or about 7 minutes.

[061] In one embodiment, the irradiation of the substrate occurs at greater than about 100mm from the electromagnetic radiation source. In an embodiment, the irradiation of the substrate occurs at greater than 150mm from the electromagnetic radiation source. In some embodiments, the irradiation of the substrate occurs at greater than 250mm from the electromagnetic radiation source. In embodiments, the irradiation of the substrate occurs at about 150mm or about 250mm away from the electromagnetic radiation source. [062] The application of the haloform solution may be carried out by spray, misting, rolling, wiping or nano produced source of the haloform solution to assist in applying a uniform and continuous film of the haloform solution to the irradiated surface to ensure a continuous modified polymer surface that is suitable to be adhesively bonded with adhesives. It is postulated that the modified surface attains a higher surface energy after the haloform coating is applied and retains the higher surface energy for long periods of time (in the order of days and months and possibly longer) thereby allowing adhesive attachment of the modified surface to other objects or materials in the future. As a result, the modified surface of the polymer object may be utilized for painting, printing or some form of bonding at a time in the future. An aqueous solution of HPLC grade chloroform (99%) and/or Bromoform (98%) was used for modifying the surface of the polyolefin object in at least some embodiments.

[063] In at least some method embodiments, it has been observed by the inventor that optimum results may be achieved (in terms of improved adhesive strength/capabilities of the treated bonding surface of the polymer object) when the step of applying the haloform solution is carried out soon after and within a limited time period after the irradiation step. In some embodiments, the step of applying the haloform solution may be carried out soon after the heat energization or ionization step. In one embodiment, haloform treatment occurs directly or within a predetermined time limit of the electromagnetic radiation treatment. In an embodiment, ultraviolet radiation is applied after haloform treatment. It has been found by the inventor that the delay between the initial irradiation step and the subsequent haloform application step should preferably be no more than ten minutes. It must be noted that exact time between the first and second step may be varied.

[064] The polymer is suitably a polyolefin. The polyolefin is a homopolymer of an a- olefin or a copolymer of an a-olefin with another compound containing one or more unsaturated groups (e.g. a copolymer of two a-olefins). An a-olefin is a straight or branched chain compound having an unsaturated group at one end of chain. Among preferred a-olefins are C1-12 alkylenes, more preferable a-olefins include ethylene, propylene and butylenes, with ethylene and propylene most preferred. For example the polyolefin object described herein may be an ethylene or propylene containing polymer or copolymer. Copolymers can be any type of copolymer, e.g. without limitation, they may be random copolymers, block copolymers, or alternating copolymers. Among useful polyolefins are blends of one or more polyolefins, for example polypropylene and polyethylene, and blends of one or more polyolefins with one or more of other known thermoplastic polymers, such as polyamide, polyethylene terephthalate, polybutylene terephthalate, polystyrene, a styrene block copolymer, a copolymer of styrene and acrylonitrile, a terpolymer of styrene, acrylonitrile and butadiene, polyphenylene oxide, polyacetal, polyetherimide, polycarbonate, or mixtures thereof. The blends of one or more polyolefins with other known thermoplastic polymers preferably contain about 50 percent by weight or greater of the polyolefins, more preferably 75 percent by weight or greater and most preferably about 90 percent by weight or greater. Examples of preferred ethylene copolymers include copolymers containing ethylene monomers and a second a-olefin which has from about 3 to about 12 carbon atoms. Examples of preferred propylene copolymers include copolymers containing propylene monomers and a second, different a-olefin which has from about 2 to about 12 carbon atoms. In one aspect of the invention, the polyolefin comprises or consists essentially of a propylene copolymer (e.g. a random copolymer) containing from about 2 to about 30 weight percent ethylene, more preferably from about 10 to 25 weight percent ethylene, based on the total weight of the polyolefin. The polyolefin may be characterized by a weight average molecular weight. The weight average molecular weight of the polyolefin may be greater than about 5,000, preferably greater than about 20,000 and more preferably greater than about 100,000. The weight average molecular weight of the polyolefin may be suitably less than about 12,000,000, more suitably less than about 5,000,000, preferably less than about 1,000,000 and more preferably less than about 500,000. In one embodiment, the polyolefin is polypropylene.

[065] The polyolefins useful in the polyolefin structures modified by the exemplary methods of the invention may further comprise one or more reinforcing materials, for example reinforcing fibers, fillers or impact modifiers. These materials are typically utilized to adjust the basic properties of polyolefins to meet the property requirements of particular customers or uses of the structures. The particular materials chosen and amounts of such materials are chosen to provide the desired properties of the structures. Reinforcing materials are typically utilized to improve the strength of the polyolefin structures. Any reinforcing materials and any amount of reinforcing materials which improve the strength of the polyolefin structures may be utilized in the polyolefin structures of the invention. The reinforcement material can include particles, chopped materials, strands, combinations thereof, or the like. Preferably, the reinforcement material includes fibers and more preferably includes fibers of glass, carbon, nylon, graphite, polyester, polyamides (e.g. aramides), polyethylenes (e.g., Ultra-high- molecular-weight polyethylene; UHMWPE) and mixtures thereof. The amount of fibers is chosen to provide the desired properties of the polyolefin structures. The amount of the fibers may be up to about 100 parts by weight of 50 parts by weight, and desirably from about 10 to about 30 parts by weight for every 100 parts by weight of the polyolefin's structure.

[066] In one embodiment, the polymer or polymer substrate may further comprise one or more modifiers. The one or more modifiers provide desirable properties to the polymer or polymer substrate, such as temperature modification and strength. Nonlimiting examples of the modifiers include graphene and glass fibres. It will be appreciated by the person skilled in the art that the above list is not an exhaustive list of modifiers and that other modifiers can be utilized which will be readily apparent to the person skilled in the art.

[067] An advantage of utilizing electromagnetic radiation over flame or corona discharge is that electromagnetic radiation can be applied for a longer time without being detrimental to the integrity of the substance being treated. In this regard, flame or corona discharge (or similar treatment) can lead to the integrity of the substance being affected due to the high temperatures. For instance, if the substrate is treated for a greater than optimal time then the substrate may be burned. However, with electromagnetic radiation, treatment may occur for a longer time period without affecting the structural integrity of the substrate. As such, an advantage of using electromagnetic radiation over flame or corona discharge is that there is a larger optimal treatment time when compared to the treatment with flame or corona discharge. One disadvantage of using more aggressive treatment, such as flame or corona discharge, is that buckling can occur during treatment. In this regard, the substrate will curl in on itself and this is undesired. [068] Furthermore, the use of electromagnetic radiation significantly reduces the chance of affecting the visual appearance or distortion in the substrate. In this regard, the use of electromagnetic radiation is not as harsh a treatment method as with flame or corona discharge. In this regard, flame or corona discharge treatment can result in overtreatment within a short period of time. Overtreatment can lead to accelerated aging of the substrate which is obviously a disadvantage. In contrast, the overtreatment of electromagnetic radiation occurs at a much greater timeframe.

[069] The use of electromagnetic radiation also allows for the treatment of substrates of low thickness. Given that the treatment with electromagnetic radiation is less destructive, low thickness substrates can be treated. In contrast, with flame or corona discharge, low thickness substrates can be easily distorted due to the destructive and harsh treatment. In one embodiment, the use of electromagnetic radiation allows for substrates of less than 1mm to be treated. Furthermore, the use of electromagnetic radiation does not damage surface textures of the substance being treated by virtue of their less destructive nature. In one embodiment, the object being treated has a thickness of suitably less than 1mm, more suitably less than 2mm, preferably less than 3mm and more preferably less than 5mm.

[070] It will be appreciated that surface treatments can be quite expensive with specialized machinery. It is postulated that the present invention can be incorporated into production plants easily because the electromagnetic radiation source are relatively common, and the treatment of the substrate is relatively is not time sensitive due to it being less destructive. As such, the surface treatment using electromagnetic radiation are more easily automated without necessarily requiring the use of precision machinery. Furthermore, it is postulated that the presently claimed invention is cost effective.

[071] The present invention also allows for the treatment of uneven or contoured surfaces as the electromagnetic radiation can be easily evenly applied over a substrate. In contrast, flame or corona discharge are extremely difficult to evenly apply over a substrate and can lead to defects in the substrate being treated.

[072] Furthermore, the present invention allows for an easily commercialized system that can be timed and automated in factories. The thickness of the substrate is also of limited importance for the reasons mentioned hereinabove. The present invention also allows for a large number of substrates to be treated.

[073] It is envisaged that the present method can be utilized in ballistics and, in particular, providing greater safety in objects such as bullet proof vests. Furthermore, delamination of the polymer fibres within the polymer/adhesive matrix will be greatly reduced.

USE FOR EMBODIMENTS OF THE INVENTION

Three non-limiting examples have been described below to demonstrate usage of the surface modified polyolefin objects for marine applications. An example has also been shown for other purposes such as improving printing on polyolefin objects. It must be understood that the invention described herein is not in any way limited by end use of the surface modified polyolefin object prepared by embodiments of the present invention.

Example 1

Boat hulls can be large and small and are typically built from materials such as steel, aluminum, wood and fiberglass. However, these materials can undergo many forms of degradation due to the harsh marine environmental conditions. The application of the surface modified polyolefin prepared using the exemplary method of the present invention may be bonded over an outer surface of a boat hull to address some of the degradation related issues. In some instances it is envisioned that use of the surface modified polyolefin may completely overcome many issues of degradation. In this regard, the method of the present invention in at least some embodiments. One of the more difficult issues associated with the use of polyolefin is the issue of attaching or bonding polyolefin to metallic surfaces such as steel without the use of mechanical fasteners. Untreated polyolefin surface has low surface energy which reduces the ability of such a surface to adhesively bond to any adhesive. Surface modification of polyolefin by adopting embodiments of the presently described method improve the surface of the surface treated polyolefin object to bond or glue the surface treated polyolefin to either new ships or retro-fit surface treated polyolefin "skins" to in-service ships which can result in the reduction in viscous drag (viscous drag accounts for approximately 70 % of ship hull drag). Example 2

Antifouling on boats is important to prevent bio-fouling of the hull surface to prevent or minimise the reduction in boat performance due to marine biological organisms. The outer surface of polyolefin objects such as polyolefin sheets may be pre-treated using embodiments of the invention as previously described. The inner polyolefin surface can be bonded to the surface of the boat hull as described in Example 1. The joints between the attached sheets can be plastic welded but these weld joints may be treated to increase the surface energy using the invention described. The untreated welded joints will only have a low energy surface if not treated according to the processes outlined in the invention. After the welded joints have been onsite treated using the invention as described, the new waterproof polyolefin skin attached over the surface of the boat hull can now be painted using appropriate bio fouling paints pretested prior to application. Surface energy requirements for bonding varies with different paints but many commercially available paints will be suitable for use with the higher surface energy level polyolefin treated using the invention described including biofouling paints.

Example 3

Printing on polyethylene sheeting has been a challenge for the print industry. Applications on polyolefin for signage or decoration in commercial shopping centers and hospitals for example, where regular and aggressive cleaning is carried out, has been strictly limited.

Printing on polyolefin products has been limited to the short term usage of the print material, but a permanent long term print bond has been sought. Polyethylene sheeting surface treated with the exemplary method of the present invention allows the treated surface to maintain a high surface energy thereby making the surface treated polyolefin more suitable for printing by allowing stronger bonds between print inks and the treated polyethylene surface.

EXPERIMENTAL TEST RESULTS

Lap shear test specimens were prepared from the polyethylene samples (the polyethylene samples referred to hereinafter in the examples was high density polyethylene (HDPE)). An adhesive bead was applied along the width of the polyethylene samples. The polyethylene samples were glued using two types of adhesives (Samson Adhesive ISR 70-03 and Terosan 939) and various samples of polyethylene, steel and wood were glued to the polyethylene samples. The samples were allowed to cure at the condition at room temperature.

The samples were pulled at a rate of 13 mm/minute with a Universal Machine Instron Tester under the ASTM D5868 standard. The load at break of the sample was recorded. A number of test specimens were tested which included treatment with microwave radiation or infrared radiation followed by treatment with bromoform or chloroform. These tests were compared to test specimens treated with plasma flame.

Sample 1G-1-1-19 (Polyethylene bonded to Polyethylene)

Each polyethylene sample was initially treated with a plasma flame to ionise the surface followed by surface treatment using Bromoform. The polyethylene samples were bonded to each other using Samson Adhesive ISR 70-03.

Table 1 illustrates the Lap shear test results for Sample 1G-1-1-19.

Sample 1W-1-1-19 (Polyethylene bonded to Polyethylene)

Each polyethylene sample was initially treated with a plasma flame to ionise the surface followed by surface treatment using Bromoform. The polyethylene samples were bonded using another adhesive Terosan 939.

Table 2 illustrates the Lap shear test results for Sample 1W-1-1-19.

Sample 2G-1-1-19 (Polyethylene bonded to Polyethylene)

Each polyethylene sample was initially treated with a plasma flame to ionise the surface followed by surface treatment using Chloroform. The polyethylene samples were bonded using Samson Adhesive ISR 70-03.

Table 3 illustrates the Lap shear test results for Sample 2G-1-1-19.

Shown in Figure 7 is a photograph of the results of the lap shear test.

Sample 2W-1-1-19

Each polyethylene sample was initially treated with a plasma flame to ionise the surface followed by surface treatment using Chloroform. The polyethylene samples were bonded using another adhesive Terosan 939.

Table 4 illustrates the Lap shear test results for Sample 2W-1-1-19.

Comparative Sample with no treatment (Sample 7G-1-1-19)

Two polyethylene samples were bonded to each other without any treatment on the bonding surfaces. The polyethylene samples were bonded using Samson Adhesive ISR 70-03.

Table 5 illustrates the Lap shear test results for Sample 7W-1-1-19.

Shown in Figure 8 is a photograph of the results of the lap shear test.

Comparative Sample with no treatment (Sample 7W-1-1-19)

Two polyethylene samples were bonded to each other without any treatment on the bonding surfaces. The polyethylene samples were bonded using Terosan 939.

Table 6 illustrates the Lap shear test results for Sample 7G-1-1-19.

Sample PSG-22-1-19 Each polyethylene sample was initially treated with a plasma flame to ionise the surface followed by surface treatment using Bromoform. The polyethylene samples were bonded to steel using Samson Adhesive ISR 70-03.

Table 7 illustrates the Lap shear test results for Sample PSG-22-1-19

Sample PSW-22-1-19

Each polyethylene sample was initially treated with a plasma flame to ionise the surface followed by surface treatment using Bromoform. The polyethylene samples were bonded to steel using Terosan 939.

Table 8 illustrates the Lap shear test results for Sample PSW-22-1-19

Sample PWG-22-1-19

Each polyethylene sample was initially treated with a plasma flame to ionise the surface followed by surface treatment using Bromoform. The polyethylene samples were bonded to wood using Samson Adhesive ISR 70-03.

Table 9 illustrates the Lap shear test results for Sample PWG-22-1-19

Sample PWW-22-1-19

Each polyethylene sample was initially treated with a plasma flame to ionise the surface followed by surface treatment using Bromoform. The polyethylene samples were bonded to wood using Terosan 939.

Table 10 illustrates the Lap shear test results for Sample PWW-22-1-19

SAMPLE SSG-20-1-19 (Comparative Example)

This test was carried out to compare lap shear characteristics of the previously described samples with two steel samples that were bonded to each other using the Samson Adhesive ISR 70-03.

Table 11 illustrates the Lap shear test results for Sample SSG-20-1-19

SAMPLE SSW-20-1-19 (Comparative Example)

This test was carried out to compare lap shear characteristics of the previously described samples with two steel samples that were bonded to each other using the Terosan 939 adhesive.

Table 12 illustrates the Lap shear test results for Sample SSW-20-1-19

SAMPLE WWG-20-1-19

This test was carried out to compare lap shear characteristics of the previously described samples with two wood samples that were bonded to each other using the Samson Adhesive ISR 70-03.

Table 13 illustrates the Lap shear test results for Sample WWG-20-1-19

SAMPLE WWW-20-1-19 This test was carried out to compare lap shear characteristics of the previously described samples with two wood samples that were bonded to each other using the Terosan 939 adhesive.

Table 14 illustrates the Lap shear test results for Sample WWW-20-1-19.

SAMPLE 1 - HDPE-TM-B

Each polyethylene sample was initially irradiated with microwave radiation for 6 minutes, followed by surface treatment using bromoform, and then followed by ultraviolet irradiation. The polyethylene samples were bonded using Samson Adhesive ISR 70-03.

Table 15 illustrates the Lap shear test results for Sample 1 -HDPE-TM-B

Shown in Figure 1 is a photograph of the results of the lap shear test.

SAMPLE 2 - HDPE-TM-C

Each polyethylene sample was initially irradiated with microwave radiation for 6 minutes, followed by surface treatment using chloroform, and then followed by ultraviolet irradiation. The polyethylene samples were bonded using Samson Adhesive ISR 70-03.

Table 16 illustrates the Lap shear test results for Sample 2 -HDPE-TM-C

Shown in Figure 2 is a photograph of the results of the lap shear test.

SAMPLE 3 - Nylon-TIR-I

Nylon samples were initially irradiated with infrared radiation for 7 minutes, followed by surface treatment using iodine (tincture of iodine, 7% iodine), and then followed by ultraviolet irradiation. The nylon samples were bonded using Samson Adhesive ISR 70-03.

Table 17 illustrates the Lap shear test results for Sample 3 -Nylon-TIR-I

Shown in Figure 3 is a photograph of the results of the lap shear test.

SAMPLE 4 - Ultra high density molecular weight polyethylene (UHMWPE)-TIR-C Ultra high density molecular weight polyethylene (UHMWPE) samples were initially irradiated with infrared radiation for 7 minutes, followed by surface treatment using chloroform, and then followed by ultraviolet irradiation. The nylon samples were bonded using Samson Adhesive ISR 70-03.

Table 18 illustrates the Lap shear test results for SAMPLE 4 - Ultra high density molecular weight polyethylene (UHMWPE)-TIR-C

Shown in Figure 4 is a photograph of the results of the lap shear test.

SAMPLE 5 - Nylon-TIR-C

Nylon samples were initially irradiated with infrared radiation for 7 minutes, followed by surface treatment using chloroform, and then followed by ultraviolet irradiation. The nylon samples were bonded using Samson Adhesive ISR 70-03.

Table 19 illustrates the Lap shear test results for Sample 5 -Nylon-TIR-C

Shown in Figure 5 is a photograph of the results of the lap shear test.

SAMPLE 6 - HDPE-TIR-C

Each polyethylene sample was initially irradiated with infrared radiation for 7 minutes, followed by surface treatment using chloroform, and then followed by ultraviolet irradiation. The polyethylene samples were bonded using Samson Adhesive ISR 70- 03.

Table 20 illustrates the Lap shear test results for Sample 6 -HDPE-TIR-C

Shown in Figure 6 is a photograph of the results of the lap shear test.

[074] The above described examples show that samples that were treated with electromagnetic radiation (either infrared radiation or microwave radiation) and surface treated with chloroform or bromoform, resulted in at least comparable results with samples that were treated with plasma flame. Furthermore, some examples shows superior lap shear test results.

[075] As previously mentioned, even in situations where the adhesion results are comparable to the samples that were treated with plasma flame, the present invention has at least the advantages of being a less aggressive treatment and allows for easier application of the method.

[076] For instance, microwave treated example (SAMPLE 2 - HDPE-TM-C) and infrared treated example (SAMPLE 6 - HDPE-TIR-C) show superior results to the corresponding plasma flame treated example (Sample 2G-1-1-19). Furthermore, all samples (SAMPLE 1 - HDPE-TM-B, SAMPLE 2 - HDPE-TM-C, SAMPLE 3 - Nylon- TIR-I, SAMPLE 4 - Ultra high density molecular weight polyethylene (UHMWPE)-TIR- C, SAMPLE 5 - Nylon-TIR-C and SAMPLE 6 - HDPE-TIR-C) show improved adhesive strength when compared with the untreated samples (7G-1-1-19, 7W-1-1- 19). Additionally, the test results show that the present invention can be utilized with a number of different substrates.

[077] Figures 1-6 show photographs of the results of the lap shear tests for Samples 1-6. The figures show that the adhesive (Samson Adhesive ISR 70-03) bonded strongly to the treated surface and, while the adhesive failed during testing, there is still a fine coating of adhesive left on the substrate. This appears to indicate that the adhesive bonded extremely strongly to the treated surface. In this regard, as shown in Figure 8, no treatment with electromagnetic radiation resulted in the adhesive completely separating from the substrate. This indicates that the adhesive bonded weakly to the surface. As shown in Figure 7, treatment with plasma flame resulted in a number of samples wherein the substrate is shown to cleanly separate from the substrate. This appears to indicate that the application of the plasma flame treatment is not uniform and may result in inconsistent surface treatment. As such, the treated substrate may comprise weak adhesion portions that compromise the seal between the adhesive and the substrate.

[078] Figure 3 shows a photograph of the lap shear test for Sample 3. Sample 3 utilized iodine. As shown, the use of iodine (and likely bromine) for treatment results in staining on the surface (treated end of the lap area). In comparison, Figure 5 (the use of chloroform) results in no staining of the surface. As such, another advantage of the use of a haloform is that no significant staining is observed. Furthermore, the lap shear test results appear to indicate that the use of chloroform results in a stronger surface adhesion than the use of iodine.

[079] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. The term “comprises” and its variations, such as “comprising” and “comprised of” is used throughout in an inclusive sense and not to the exclusion of any additional features.

[080] It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect.

[081] The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

Claims

1. A method of treating a surface of a polymer or polymer composite object, the method comprising the steps of: irradiating bonding portions said object with electromagnetic radiation; and applying a haloform CHX₃ or its derivatives to said bonding portions, wherein X is a halogen.

2. The method in accordance with claim 1, wherein the step of applying the haloform solvent is undertaken within a pre-determined time period after the ionising step.

3. The method in accordance with claim 2, wherein the pre-determined time period is no more than 2 hours, or less than 1 hour, or less than 30 minutes, or less than 20 minutes, or less than 15 minutes, or less than 5 minutes.

4. The method in accordance with any one of the preceding claims, wherein the step of applying the haloform comprises one or more of the following: spraying, misting, rolling, wiping the haloform solvent on the bonding portions.

5. The method in accordance with any one of the preceding claims, wherein the electromagnetic radiation is infrared radiation, microwave radiation, x-ray radiation, ultraviolet radiation and/or gamma radiation.

6. The method in accordance with claim 5, wherein the microwave radiation source comprises a microwave oven.

7. The method in accordance with any one of the preceding claims, further comprising step of irradiating the bonding portions with ultraviolet radiation.

8. The method in accordance with any one of the preceding claims, wherein the polymer is a polyolefin and the polymer composite object is a polyolefin composite object.

9. A method of bonding a polymer object with a surface, the method comprising the steps of: irradiating bonding portions said polymer object with electromagnetic radiation; and applying haloform CHX₃ or a derivative thereof to said bonding portions to form modified bonding portions, wherein X is a halogen; applying one or more adhesives to the modified bonding portions to bond the modified bonding portions of the polyolefin object; and bonding said bonding portions of with the surface, wherein the surface is selected from the group consisting of a metallic surface, metallic mesh, fabric or mat of polymer, polyethylene or polyethylene amide origin.

10. The method in accordance with claim 9, wherein the surface is a metallic surface.

11. The method in accordance with claim 9 or claim 10, wherein the polymer object is a polyolefin object.

12. The method in accordance with any one of claims 9 to 11, wherein the electromagnetic radiation is infrared radiation, microwave radiation, x-ray radiation, ultraviolet radiation and/or gamma radiation.

13. A method of treating a surface of a polymer object, the method comprising the steps of: irradiating bonding portions said polymer object with electromagnetic radiation; and applying a halogenated solvent or a derivative thereof to said bonding portions.

14. The method in accordance with claim 13, wherein the polymer object is a polyolefin object.

15. The method in accordance with claims 13 or claim 14, wherein the electromagnetic radiation is infrared radiation, microwave radiation, x-ray radiation, ultraviolet radiation and/or gamma radiation.

16. A method of forming a polymer object with at least one bonding surface, the method comprising the steps of: preparing a resinous blend comprising a iow surface energy polymer; transferring the resinous blend to an extrusion apparatus; extruding the resinous blend via the extrusion apparatus to form the extruded polymer object; irradiating bonding portions of said extruded polymer object with electromagnetic radiation; and applying a haloform CHX₃ or a derivative thereof to said bonding portions of, wherein X is a halogen.

17. The method in accordance with claim 16, wherein the polymer object is a polyolefin object.

18. The method in accordance with claims 16 or claim 17, wherein the electromagnetic radiation is infrared radiation, microwave radiation, x-ray radiation, ultraviolet radiation and/or gamma radiation.

19. A polymer object adapted for being adhesively bonded, the polymer object comprising: a bulk volume comprising a low surface energy polyolefin; an outer surface having one or more bonding regions comprising an irradiated surface with electromagnetic radiation, wherein the irradiated surface comprises a coating of a haloform CHX₃ or a derivative thereof.

20. The method in accordance with claim 19, wherein the polymer object is a polyolefin object.

21. The method in accordance with claims 19 or claim 20, wherein the electromagnetic radiation is infrared radiation, microwave radiation, x-ray radiation, ultraviolet radiation and/or gamma radiation.