IE87229B1 - Improved transport equipment - Google Patents

Abstract

A method of manufacturing an item of traffic equipment , comprises moulding a main body from an elastomeric material in a mould at an elevated temperature; removing the main body from the mould wherein the main body is at an intermediate temperature between the elevated moulding temperature and ambient temperature; placing a pre-formed piece of a thermoplastic paint sheet material in contact with a surface of the main body at the intermediate temperature; and applying heat to an outward facing surface of the preformed piece of thermoplastic paint sheet material so as to cause bonding between the contacting surfaces of the pre-formed piece of thermoplastic paint sheet material and the main body. An item of traffic equipment, comprises a main body formed from a moulded elastomeric material having a relief pattern on its outer surface defining at least one recess; and a pre-formed piece of thermoplastic paint sheet material of substantially the same shape and size as the at least one recess fitted within the at least one recess; wherein the a pre-formed piece of thermoplastic paint sheet material is directly bonded to the main body. <Figure 2>

Description

[0048] A core advantage of the present invention over the known prior art is to provide an item of traffic equipment of dense rubber or rubber-like material, on which a significantly larger surface area of its body can be provided with reflective means, so as to significantly improve its visibility in low light conditions.

[0049] This, and other, advantages are attained by using reflective thermoplastic paint segments or portions directly applied to the surface of the body and bonded thereto.

[0050] Thermoplastic paint is known for use in road marking, and preformed thermoplastic road markings are known whereby a sheet of pre-formed thermoplastic “paint” is cut into shapes by the manufacturer, ready to position onto an asphalt or concrete pavement surface. Preformed thermoplastic markings of this type are typically put in place on the road surface and then applied using a propane heat torch. Reflective thermoplastic road line marking tape is also known, and available in a variety of colours. Once again, such tape can be placed as required on the road or pavement surface, and then applied using a gas torch to melt the tape onto the road/pavement surface. Some thermoplastic 17/08/2020 tapes of this type may have integrated glass beads to improve the reflectiveness of the tape. Preformed thermoplastic tape of these types must be applied at between 190 and 200°C to ensure good adhesion. This means that the gas torch, which burns at temperatures in excess of 2000°C, must be applied over the tape for a sufficient period of time for the thermoplastic to reach the desired melting temperature and cause adhesion. It is for this reason that they should not be used on new asphalt until the surface has settled for a period of time, as this process is likely to soften the new asphalt beneath the tape. If lower temperatures are used, known preformed thermoplastic tapes could not be heated to a sufficiently high temperature to adhere sufficiently strongly.

[0051] Thus, whilst such preformed thermoplastic tapes may be highly effective for providing markings on surfaces such as roads and pavements, which can withstand very high temperatures without deformation, they are unsuitable for use on materials which cannot withstand such temperatures, and it has not, therefore, previously been considered to utilise preformed thermoplastic tape or sheet on anything other than roads, pavements and similar substrates.

[0052] The present invention, on the other hand, seeks to address the principal problem of how to significantly increase the visibility of an item of traffic equipment, such as a speed ramp, by increasing the surface area carrying reflective elements using segments or portions of preformed thermoplastic paint bonded to the surface of the equipment.

[0053] A problem addressed by the present invention is, therefore, how to provide a preformed thermoplastic tape or sheet that can be used to form a sufficiently strong bond with a substrate formed of, for example, a dense rubber injection moulding formation, which cannot withstand temperatures above, say, 60-70°C or so for any significant length of time, without deformation.

[0054] In order to achieve this object, the present invention seeks to provide a reflective thermoplastic paint that utilises the softening point of the material (rather than its, higher, melting point) to bond (rather than adhere) the thermoplastic paint to the substrate below. As an example, 17/08/2020 a thermoplastic paint having a softening point of 65-130°C and a relatively high flashpoint, for example, >230°C, is proposed. Bonding between the thermoplastic paint and a rubber substrate beneath occurs at a much lower temperature than that required to melt a thermoplastic tape to a road or pavement. A pre-formed piece of thermoplastic material having a bonding temperature of around 150 °C is considered suitable. This means that the thermoplastic element does not need to be heated to the high temperature required for road markings, and the method described herein can be performed using a focussed heat source at a relatively high temperature for a shorter period of time than required by prior art application processes, thus ensuring that the temperature of the underlying substrate is not raised enough during the application process to damage it, nor is the thermoplastic structure damaged during the process.

[0055] These specifications can be achieved with a number of different specific compositions of components but, in general, the bespoke reflective thermoplastic composition used in the invention comprises synthetic resin, highly refined mineral oil, aggregates, extenders, polymers, solid pigments and reflective glass beads, and the approximate proportions of a thermoplastic material used are set out below, providing a thermoplastic composition with a softening point of around 80°C and a bonding temperature of around 150°C:

[0056] Table 1 Ingredient CAS/EC No. Classification (EC) 1272/2008 Weight % Calcium Magnesium Carbonate CAS 16389-88-1 EC-No. 240-440-2 Not Classified 30-60% 17/08/2020 Soda Lime Glass Beads CAS 65997-17-3 EC-No. 266-046-0 Not Classified 0-40% Resin acids and Rosin acids, fumarated, esters with pentaerythritol CAS 94581-15-4 EC-No. 305-514-1 Cl: H 317 Allergic Skin reaction H 319 Eye Irritation. H 413 Aquatic Hazard 0-20% Polyamide resin Not Classified 0-10% Titanium Dioxide CAS 13463-67-7 EC No. 236-675-5 Not Classified 0-10% 1, 2- Benzenedicar boxy lie acid ,d i-C8-10branched alkyl esters CAS 68515-48-0 EC No. 271-090-9 Not Classified 0-5% Polymer Not Classified 0-5% Pigment Not Classified 0-5%

[0057] The exact properties of ingredients within the material, and the ratio of characteristics, can be varied more or less in relation to: • visibility/reflective performance - distance of visibility in varying light levels • anti-skid/grip performance - engagement with rubber of tyres, friction level, grip or slip when wet • Frictional/Tyre-contact durability performance - e.g. to withstand around 1,000,000 passes of vehicles.

• UV exposure/weathering durability performance - no loss of colour or fading, typical range of temperatures: -10°C to +50°C, sunlight, rain, snow 17/08/2020

[0058] The component having the primary influence on the softening/melting point and the bonding temperature of the composition is the Titanium Dioxide, and this can be varied in accordance with requirements and to accurately meet the required balance between the bonding temperature at the abutting surfaces between the pre-formed piece of thermoplastic paint and the main body, as will be described in more detail hereinafter.

[0059] In the composition described above, the glass bead content governs the retro-reflectivity of the material. The retro-reflectivity of the material might be minimised at 15-20%, optimised at around 30% and maximised at 50%. However, the beads are mixed into the composition, such that the material may need to be worn down by weather and traffic before their maximum effect can be achieved. Bearing in mind that the purpose of the speed ramp is to restrict traffic speed, the thermoplastic elements may be protected to some extent. Thus, the retro-reflectivity of the thermoplastic elements is likely to be governed primarily by the glass beads on the surface. This can then be optimised by dropping a quantity of glass beads onto the surface of the thermoplastic before it sets, thereby increasing the surface area covered by the glass beads and, in turn, the retro-reflectivity of the resultant thermoplastic sheet. The concentration of beads dropped onto the surface of the thermoplastic can also be used to determine the eventual durability and grip characteristics of the reflective elements. The glass beads can, for example, comprise Soda Lime beads having a refractive index in the range 1.45 - 1.55 (e.g. 1.5 - 1.53).

[0060] The thermoplastic sheet used to form the reflective elements can be yellow, to optimise retro-reflectivity, but other colours can alternatively or additionally be considered, depending on their intended use.

[0061] A large sheet of reflective thermoplastic material of the type described above can be preformed, and then specific shapes can be pre-cut so that, during a manufacturing process according to the invention, each reflective element can be easily removed from the sheet for application at the appropriate location on the body of the item of traffic equipment being manufactured. 17/08/2020

[0062] Referring now to Figure 2 of the drawings, a speed ramp 20 comprises one or more ramp portions 22. Each ramp portion 22 comprises a generally rectangular base, as before and a rounded convex upper or operable surface. The main body of the ramp portion is formed of dense injection moulded recycled PVC and the upper surface of the moulded body has a distinctive pattern defining a plurality of diamond and triangular recessed portions 24. There are other methods of forming the main body, for example, compression moulding.

[0063] As a step of manufacturing the item of traffic, a thermoplastic sheet, of the type described above, can be provided. The sheet can have formed therein, pre-cut segments corresponding to the recessed portions in the moulded body. Immediately following the injection moulding process for moulding the body of a ramp portion 22, and whilst its surface is still at an elevated temperature, the pre-cut segments can be removed from the thermoplastic sheet and bonded in the recessed portions in a method described hereinafter.

[0064] It will be apparent that the visibility of the leading edge (see Figure 4) of the speed ramp is of important, and one or more 26 of the recessed portions may be left without a reflective thermoplastic insert, to allow (for example) a company logo or other identifying mark to be moulded or otherwise provided therein. However, in cases in which it is useful to maximise the surface area covered by the reflective inserts, the central recesses 26 can also be provided with reflective thermoplastic inserts in the same manner.

[0065] Referring back to Figure 2 of the drawings, the speed ramp 20 can further comprise a pair of end caps 28, one at each end of an elongate ramp portion 22 or, indeed, a structure comprising a plurality of such ramp portions connected together. It can be seen, from Figure 3 of the drawings, that each ramp portion 22 is provided, at each end, with a locating lug 30 and a recess 32 which allows a number of ramp portions 22 to be connected together lengthwise. Each end cap 28 comprises a generally semi-circular base and a rounded, convex upper or operable surface to match that of the associated ramp portions 22. The main body of each end cap 28 is formed of dense injection moulded recycled 17/08/2020 PVC and the upper surface of the moulded body has (at least) a triangular recessed portion 34. As with the above-described ramp portion, a pre-cut segment of reflective thermoplastic paint can be bonded into the recessed portion 34 in the manner to be described hereinafter.

[0066] Referring to Figure 5 of the drawings, in its assembled state, a speed ramp 20 comprising a single ramp portion 22 and a pair of end caps 28 of the type described above can be seen to provide a distinctive pattern of reflective portions along the edges and close to the ends. Referring to Figure 6 of the drawings, as before, the base of the ramp portion 22 and each end cap 28 is provided with a longitudinal channel 36 to accommodate cables, in use, if required; and, referring back to Figure 3 of the drawings, as before, bolt holes 38 are provided laterally through the thickness of the bodies of both the ramp portion 22 and the end caps 28 to enable the assembled speed ramp 20 (Figures 2 and 5, for example) to be bolted onto a road or other surface.

[0067] The table below indicates the surface area of the speed ramp covered by each segment type, and defines a number of exemplary configurations of reflective thermoplastic segments that could be utilised.

[0068] Table 2 17/08/2020 Config. Central Central Central End Cap Top Profile No. Section Isosceles T riangle Type (1) Fig. 7a Qty 6 per Section Area = 5720mm2 Section Isosceles T riangle Type (2) Fig. 7b Qty 2 per Section Area = 5390mm2 Section Rhombus (Diamond) Fig. 7c Qty 2 per Section Area = 11440mm2 Section Isosceles T riangle Type (2) Fig. 7d Qty 1 per End Cap Area = 10,780mm2 Total Surface Area Coverage of Inserted Element material technology 1 Active (Area 34,320mm2) Active (Area 10,780mm2) Active (Area 22,880mm2) Active (Area 10,780mm2) 26% 2 Active (Area 34,320mm2) Active (Area 10,780mm2) Active (Area 22,880mm2) Blank 22% 3 Active (Area 34,320mm2) Active (Area 10,780mm2) Blank Blank 15% 4 Active (Area 34,320mm2) Blank Blank Blank 11% 5 Active (Area 34,320mm2) Active (Area 10,780mm2) Blank Active (Area 10,780mm2) 18%

[0069] As indicated (with reference to Figure 2 of the drawings), an assembled speed ramp has an operable surface area of 18% covered by reflective thermoplastic material (row no. 5). In the case where the two diamond shaped recesses 26 over the centre are also provided with reflective thermoplastic inserts, the operable surface area coverage can 17/08/2020 be increased to 26% (row no. 1). Other configurations are suggested in rows 2 to 4 of the illustrated table, giving an operable surface area coverage of between 11 and 22%, according to requirements. It will be appreciated that many different configurations of reflective thermoplastic inserts could be used, and the present invention is not intended to be in any way limited in this regard.

[0070] The shapes of the thermoplastic inserts described in the table above are shown in Figures 7a - 7d.

[0071] It can thus be seen that a significant proportion of the operable surface area of a speed ramp can be made highly visible by motorists in low level conditions. This level of reflective coverage has not been disclosed or suggested before, and is considered to contribute significantly to the visibility and, therefore, safety of a speed ramp. It has not previously been possible to bond reflective thermoplastic paint to a dense rubber compression moulded body and, therefore, significant innovative effort has been required by the inventors to devise a method that enables the features of the present invention to be realised.

[0072] A technical problem solved by the present invention is related to the strength of the bond between the reflective thermoplastic insert and the moulded body of an item of traffic equipment (e.g. a speed ramp). The body (e.g. ramp body) can be moulded from an elastomeric material (e.g. recycled PVC, which is inherently full of contaminants and of oily consistency). Furthermore, the thermoplastic paint cannot be melted onto the body (e.g. ramp body) to create a bond because if the moulded elastomeric material (e.g. PVC or recycled PVC) is exposed to a high temperature for the prolonged period of time to melt the thermoplastic material and cause it to “stick” to the body (e.g. ramp body), damage/deformation would be caused. A method of forming a bond between the reflective thermoplastic paint sheet material and the moulded body (e.g. moulded body of the speed ramp) will now be described in more detail. As a first step, a sheet of reflective thermoplastic material of the type described above can be formed or obtained, the sheet having pre-cut segments therein defining the 17/08/2020 shapes of the reflective portions on the finished body (e.g. speed ramp element) and matching recesses included in the moulded body. Wherein the moulded body has multiple recesses, a plurality of preformed pieces can be formed by cutting or otherwise separating a plurality of segments from a larger sheet of thermoplastic paint sheet material to respective recesses in the surface of the moulded body. The pre-formed piece(s) of thermoplastic paint sheet material can have reflective beads integrated therein.

[0073] The body (e.g. speed ramp element) is formed by a moulding process (e.g. injection moulding) using an elastomeric material (e.g. black recycled PVC material, which is considered a cost effective option within the scope of the current field of technology). The temperature inside the mould can be around 160°C, which is sufficient to melt PVC material for injection into the mould. The injection moulding process can take around 6 minutes. The main body can be moulded to have a relief pattern on its outer surface defining at least one recess, wherein the pre-formed piece of thermoplastic paint sheet material is of substantially the same shape and size as the at least one recess so as to fit within the at least one recess.

[0074] After moulding, the body is removed from the mould while it is at an intermediate temperature between the elevated moulding temperatures (i.e. the temperature at which the body is moulded) and the ambient temperature. The elevated temperature can be above 150°C and the intermediate temperature can be above 50°C. The surface temperature of the body, thus moulded, can be approximately 65°C as it comes out of the mould tool. At this point, at least one pre-formed piece of thermoplastic paint sheet material / reflective thermoplastic element is placed in contact with a surface of the body at the intermediate temperature and heat is applied to an outward facing surface of the pre-formed of thermoplastic paint sheet material so as to cause bonding between the contacting surfaces of the pre-formed piece of thermoplastic paint sheet material and the body. The application of heat can raise the temperature at the contacting surfaces to a temperature between the intermediate temperature and the elevated 17/08/2020 temperature. The heat can be applied for less than 1 minute, 10-40 seconds or 20-30 seconds for the above-described bonding to occur. For example, the reflective thermoplastic element(s) can be substantially immediately placed in the respective recess(es) defined in the operable surface of the moulded body (e.g. moulded speed ramp element) and pressed down, such that the bonding process begins immediately between the abutting surface(s) of the pre-cut segment(s) and the moulded body. Then, for example, a heat gun can be used to complete the bonding process. Such a heat gun can be directed over the outward facing surface of each segment for 20-30 seconds so as to raise the temperature of the reflective thermoplastic at the outward facing surface to a maximum of 600°C, which can be sufficient to raise the temperature at the surface abutting the body (e.g. ramp body) to around 120°C and no more than around 130°C. The thermoplastic composition can have a bonding temperature with recycled PVC of around 150°C, and wherein the temperature at the surface of the body (e.g. ramp body) is already 65°C, this is sufficient to provide a strong bond.

[0075] A number of different means of heating the reflective thermoplastic segment can be used. For example, a heat gun (which emits a stream of hot air, heated by an element and propelled by a fan, via a nozzle) can be used for a number of reasons. Firstly, it can be very focused, such that it can be ensured that no heat is applied to the surrounding mould, which would otherwise damage it. Secondly, it is significantly safer and more practical than the propane (or similar gas) guns required to bond conventional thermoplastic tape to road surfaces.

[0076] Once the mould and reflective thermoplastic segments thereon have cooled and fully solidified, a high bond strength is completed.

[0077] The above-described process of applying and bonding the reflective thermoplastic segments to the moulded body can be performed manually, or some or all steps of the method could be automated, and the present invention is not necessarily intended to be limited in this regard. 17/08/2020

[0078] The workable solution thus developed uses the raised surface temperature of the moulded body to reduce the temperature required at the abutting surface of the thermoplastic paint segment to meet the bonding temperature, so as to ensure the bond strength is sufficient and durable whilst minimising the risk of damage to the thermoplastic structure or the underlying moulded body (e.g. ramp body).

[0079] The resultant item of traffic equipment (e.g. speed ramp) provides visibility features across the entire upper surface of the product, where it matters most. The surface area covered by these visibility features is significant, with the individual inserts being relatively large in size (compared with, say, the inserted reflective pieces used in the prior art).

[0080] Vehicle tyres are in continuous and abrasive contact with the operable surface of the speed ramp. In prior art devices, this causes the surface of the speed ramp to become slippery over time, as well as contributing to its wear. In contrast, in the present invention, such continuous use actually increases the reflectivity of the inserts, as thermoplastic is worn away from embedded glass beads. The anti-skid properties of the speed ramp are maintained for a longer period of time, again (at least partly) due to the frictional contribution of the glass beads. Thus, the present invention provides a novel method of manufacture that enables moulded rubber items of traffic equipment, such as speed ramps or railway sleepers, to be provided with regions of reflective thermoplastic material in order to provide a predetermined proportion of reflective surface area. Such items of traffic equipment, thus manufactured, have significantly improved visibility and durability characteristics compared with known prior art solutions. An additional benefit of items of traffic equipment manufactured in accordance with a method of the invention, is the improved grip characteristics (which can be customised according to application and requirements) and the significantly reduced loss of grip over time.

[0081] Modifications and variations can be made without departing from the scope of the invention. For example, an alternative speed ramp is illustrated in Figures 8a and 8b of the drawings. In this case, the 17/08/2020 speed ramp comprises a ramp body 100 having a generally rectangular base and a rounded operable surface. The ramp body is, as before, formed of injection moulded rubber, with recesses 102 formed on the leading and trailing edges, and other relief pattern features 103 are also provided, as required, to contribute to its grip characteristics. A set of longitudinal channels 104 (three, in this specific case) are provided in the ‘upper’ surface of the ramp body 100. A planar cover 106 is hinged, longitudinally, so as to movable relative to the ‘upper’ surface of the ramp body 100 between a closed position in which it covers the channels 104, as shown in Figure 8a of the drawings, and an open position in which the channels 104 are exposed, as shown in Figure 8b of the drawings. The cover can, again, be formed of injection moulded rubber (e.g. Polypropylene co-polymer material) and provided, on its outer surface, with a relief pattern to contribute to the grip characteristics thereof. The outer surface of the cover 106 can be yellow (or other colour)to improve its visibility characteristics, and this colour can be formed in the polymer moulding process in a manner that will be known to a person skilled in the art. A hinge can be provided in the form of a hard polymer rod that passes through juxtaposed apertures on the edge of the cover and the main body, so as to connect the two elements together. Reflective thermoplastic inserts, of the type described above, are bonded within the recesses 102 formed on the leading and trailing edges of the ramp body 100, as before. A locating lug 108 and recess 110 is provided at each end of the ramp body 100 (adjacent the base) to enable a plurality of such ramp bodies to be connected together longitudinally.

Claims (11)

1. Claim 1. A method of manufacturing an item of traffic equipment, comprising: - moulding a main body from an elastomeric material in a mould at an elevated temperature above 150°C; - removing the main body from the mould wherein the main body is at an intermediate temperature above 50°C between the elevated moulding temperature and ambient temperature; - placing a pre-formed piece of a thermoplastic paint sheet material in contact with a surface of the main body at the intermediate temperature; and - applying heat to an outward facing surface of the pre-formed piece of thermoplastic paint sheet material for less than 1 minute so as to raise the temperature of the outward facing surface to a maximum of 600°C and to raise the temperature of the surface contacting the main body to a maximum of no more than 130°C so as to cause bonding between the contacting surfaces of the pre-formed piece of thermoplastic paint sheet material and the main body.

2. Claim 2. A method as claimed in claim 1, wherein the step of applying heat to an outward-facing surface of the pre-formed piece of thermoplastic paint sheet material raises the temperature at the contacting surfaces to a temperature between the intermediate temperature and the elevated temperature.

3. Claim 3. A method as claimed in any preceding claim, wherein the thermoplastic paint sheet material has a softening point between 65 and 130°C.

4. Claim 4. A method as claimed in any preceding claim, comprising moulding the main body to have a relief pattern on its outer surface defining at least one recess, wherein the pre-formed piece of thermoplastic paint sheet material is of substantially the same shape and size as the at least one recess so as to fit within the at least one recess.

5. Claim 5. A method as claimed in claim 4, wherein the main body has multiple recesses, the method including forming a plurality of pre-formed pieces by cutting or otherwise separating a plurality of segments from a 17/08/2020 larger sheet of thermoplastic paint sheet material to respective recesses in the surface of the main body.

6. Claim 6. A method as claimed in any preceding claim, wherein the preformed piece of thermoplastic paint sheet material has reflective beads integrated therein.

7. Claim 7. A method as claimed in any preceding claim, wherein the elastomeric material is PVC.

8. Claim 8. A method as claimed in claim 7, wherein the elastomeric material is recycled PVC, and the thermoplastic paint sheet material has a bonding temperature of around 150°C with the moulded elastomeric material.

9. Claim 9. A method as claimed in any preceding claim, comprising applying heat to the outward facing surface of said pre-formed piece of thermoplastic paint sheet material for 10 -40 seconds.

10. Claim 10. A method as claimed in claim 9, comprising applying heat to the outward facing surface of said pre-formed piece of thermoplastic paint sheet material for 20 - 30 seconds.

11. Claim 11. A method as claimed in any preceding claim, comprising applying heat to the outward facing surface so as to raise the temperature of the surface contacting the main body to a maximum of 120°C.