GB2520058A

GB2520058A - A method of making a photopolymer mould

Info

Publication number: GB2520058A
Application number: GB1319739.7A
Authority: GB
Inventors: Andrew Mark Dale; Eric Matthew Barrett
Original assignee: GRAPHIC IP Ltd
Current assignee: GRAPHIC IP Ltd
Priority date: 2013-11-08
Filing date: 2013-11-08
Publication date: 2015-05-13
Anticipated expiration: 2033-11-08
Also published as: GB201319739D0; GB2520058B

Abstract

Method of casting concrete comprising steps of: mixing a metal powder into a concrete mix, putting the mixture into a mould, leaving the mixture to set forming a product, removing the product from the mould and finishing the products surface. The concrete may be a colloidal system. The mixture may include a plasticiser and a viscosity modifying agent. The mixing of the metal powder may use a high speed shearing means. The concrete mix may be self levelling, providing flow and degassing properties. The mix may include hydration accelerants and/or a reinforcement element. The metal powder may be tin, bronze, brass and/or copper. A second mixture, with a lower ratio of metal powder to concrete, may be placed in the mould. The product may be a relief. The mould may comprise a photopolymer plate. A method of providing a photopolymer plate 2 comprises arranging a backing layer 3 on a first side of a photopolymer plate 2, arranging a masking layer 5 on a second side of the photopolymer plate 2, using a laser to form holes (23 fig 3) in the masking layer, exposing portions of material through the holes to an ultra violet source 11, 12 and removing the unexposed portions forming recesses.

Description

A.Me.thpd of Makkig aPhotopob,cner Moujd Fidofthelr)jjJn the invention relates to a method of making a 2hotopolymer mould, n particular photopolymer rnouids for casting cement products with a metallic finish.

Sackground qt.jpven There is a market for decorative surfaces and products with metallic surfaces, such as bronze sculptures, plaques and the Hke. A known method of applying a metallic finkh to a rehef is to apply a metal gild to the surface of the relief, The prohiem with a gilded surface is that it provides a poor finish, which cannot be easily joined to another gilded portion.

Another known method is to employ a lost-wax or sand casting process to product whose surfaces are then polished to expose the metal surface, which may then he patinated to achieve different aesthetic colours and firshes, However, one limitation of this process is the cost of casting metal due to both the cost of the metal and the time to fettle and finish the product.

Another known method is to produce the physical representation of the product, e.g. in glass fibre and then coat it with a mixture of metal powder in a resin binder, which is then polished and finished to achieve the desired effect. A Limitation of this approach is the time and cost to produce the 3D object and any subsequent process step to coat the product.

The invention seeks to provide a remedy/solution to alt of the above disadvantages.

Summaty of the invention in a first broad independent aspect, the Invention provides a method of casting a concrete to form a product with a metal finish comprising the steps of: * Mixing a metal powder into a concrete precursor; * Arranging said metal powder and concrete mix in a mould; * Setting said metal powder and concrete mix within said mould to form said product; * Removing said product from said mould; and * Finishing the surface of said product.

This configuration provides the advantages oft 1. ObtainIng a substantially metallic casting which is tighter and cheaper to manufacture than an traditional metal cast; 2. The cast requires no subsequent metallic coating process, therefore enabling the surface of the cast to be finished once the concrete has sufficiently cured; and 3. The finished surface is resilient to chips and scratches, because the metallic affect extends into the cast and not just on the cast's surface. The metal powder is incorporated within the top 3 to S mitlimetres of the product, because the cost of the metals powder is high and it is unnecessary to have metal throughout the mix.

Preferably, said concrete is a colloidal system comprising said metal powder in a dispersed x phase within a continuous medium. 1: Preferably, said metal powder and concrete mix further comprises a 1.25:1 to 2.5:1 metal F powder to cement ratio by weight.

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More preferably, said metal powder and concrete mix further comprises a 2:1 metal powder to cement ratio by weight Preferably, said metal powder and concrete mix further comprises a water content of 30% to 35% water to cement by weight Preferably, said metal powder and concrete mix further comprIses a plasticiser, a viscosity modifying agent (VMA) and a hydration accelerant in quantities of 2% to 10% of cement by weight These constituents improve the flow characteristics and initiate and accelerate the hydration of the concrete mix.

Preferably, said mixing of metal powder into concrete employs a high speed shearing means. This enables Ingredients of the concrete mix to be well mixed, which works the concrete through all of the mixing phases, such as an initial dry mix, then a crumbly mix, then a plastic phase and finally a more liquid phase from the plastic mix which can be poured into the mould.

Preferably, a method of casting a concrete to form a product with a metal finish, wherein said concrete mix Is a self-levelling concrete mix which provides flow and degassirig properties. This facilitates the removal of air pockets and/or bubbles within the decorative surface of the cast, thereby providing a solid and unpitted surface that is ready for finishing.

Preferably, said metal powder and concrete mix further comprises: 25. Potycarbo4ate ether polymer superplasticisers and/or; * High-molecular weight synthetic copolymer viscosity modifying agent and/or; F * Hydration acceterants Preferably, said Potycarboxylate ether polymer superplasticisers is Glenlum ACE 499 TM; High-molecular weight synthetic copolymer viscosity modifying agent is RheoMATRIX 233 F 4and Hydration accelerant Is X-SEED 100 1N The potycarboxylate accelerates the cement hydration by exposing an Increased surface of the cement particles improving their reaction with the water. The high-molecular weight synthetic copolymer viscosity modifying agent improves the dispersion of the cement paructes throughout the mix and imnroves the flow characteristics. The hydration accelerant increases the speed of the hydration process increasing the early aged strength of the concrete.

Preferably, said metal powder and concrete mix further comprises a reinforcement element, This enables the strengthening of the concrete product.

Preferably, said metal powder is: Tin and/or Bronze and/or; Brass and/or; Copper, These powders enable the product to be finished and/or patinated via chemical/heat treatments, in particular with the casting of metal sculptures.

Preferably, a method oF casting a concrete to iorrn a product with a metal finish further comnrising the step of arranging a second metal powder and concrete mix in said mould, which comprises a lower metal powder to cement ratio by weight than said metal and concrete mix, This configuration enabLes the production of the metallic cast whereby the decorative surface layer has a higher metal content, which provides the desired finished metal effect, and the second substrate layer which supports the decorative surface layer; having a Lower metal powder content because it is not re uired for the decorative purposes as it is a supporting layer. This recures the productions costs for producing the cast by reducing the amount of metallic powder incorporated within the cast. This configuration has another advantage in that it also decreases the weight of the cast due to the use of less rn etal powder within the supporting layer.

Preferably. a method in accordance with the. above features, wherein said product is a relief. This enables the casting product to be a two dimensional has relief sculpture which represents the captured. image.

Preferably, a method in accordance with the above features, wherein said mould further comprises a photopolymer plate, This enables the method to accurately capture the image data and reproduce this image data on a casting material which reacts to a laser. The laser cuts a 2D image in the laser ablatable layer & it is the subsequent exposure to UV which 6 leads to hard/soft parts of the photopolymer which give the relief when put through the washing process. Furthermore, the laser provides a means of reproducIng the required resolution of the detailed works.

This configuration is advantageous because it enables an accurate mould to be formed from a photopolyrner plate, which is based upon a captured digital image. P The laser enables the accurate detail to be incorporated within the mould by forming holes within the masking layer which allows the photopotymer plate to be exposed to the ultraviolet light whose intensity is determined by the size of the hole within the masking Layer.

Where the mould can be created by exposing the photopolymer plate to a LJV light source, which sets an image of varying depths across the photopolymer plate to form the mould; after the unexposed portions of the plate have been washed away. This is an efficIent and w cost effective way of providing an accurate high resolution mould, which incorporates a minimal number of operation/processes stages in producing the mould.

In a second broad independent aspect, a method of providing a photopotymer plate comprising the steps of * arranging a backing layer on a first side of a photopolymer plate; * arranging a masking layer on a second side of said photopolymer plate; * using a laser to form a plurality of holes within said masking layer; F * exposing portions of material in said photopolymer plate, which are exposed by said holes to an Ultra Violet ((N) light source, thereby hardening said portions of photopolymer plate that correspond with the width of each said hole; and * Removing the unexposed portions of photopolymer material to form recesses on the photopolymer plate.

This restricts the amount of ultraviolet tight to a predetermined amount, passing through the masking layer which then cures the material in the photopotymer plate to a known depth.

Preferably, a first said hole and a second said hole comprise have different widths.

Preferably, a method of providing a photopolymer plate further comprising the step of arranging a removable protective sheet on a side of said masking Layer which is opposite said photopotymer plate. The protective sheet prevents any damage to the masking layer w underneath, as any damage in the form of chips and/or scratches will cause unintended portions of the photopolymer plate to be exposed the UV light. This would seriously affect the accuracy of the intended mould design.

Preferably, said masking layer is an ablatabie layer, whereby said Laser forms said plurality of holes therein.

The ablatable layer allows the laser to burn/cut holes within the Layer, which are in accordance with the intended design of the mould, Preferably, said backing Layer is formed from a removable polyester layer. The polyester layer provides a backing layer which prevents the photopolymer plate from being exposed to the UV content within normal sunlight Preferably, a method of providing a photopolymer plate further comprising the step of exposing said backing Layer to a second LJV Light source, thereby hardening said first side of said photopolymer plate to form a relief floor. The backing Layer allows the controlled exposure of the photopolyrner plate to a second, back exposed UV Light source. The backing layer filters the ultra violet light so that it penetrates the photopolymer plate to an intended depth, therefore creating the relief floor, Preferably, said backing layer is exposed to said second UV light source for a predetermined time period. The predetermined time sets the time of the exposure of the photopolymer plate, and therefore the UV penetration into the photopoLyrrier plate. It

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Preferably, said UV tight source comprises a plurality of liv tight emitting elements.

whereby the emitted UV tight from a first said UV element overlaps with the emitted UV light from a second said liv element. This configuration enables one uniform liv tight source which Is controllable to be admitted over the entire photopotyrner plate.

Preferably, a method of providing a photopolymer plate further comprising the step oF forming a wall of said hardened photopolymer material about a portion of unexposed photopolymer material. This enables a wall about the recess within the photopotymer plate be formed, between the exposed and unexposed photopolymer material The shoulder corresponds with the exposed portions of the photopotymer plate, therefore providing the accurate design detail required for the design Incorporated within the mould.

Preferably, a photopolymer plate in accordance with any of the above features of the second aspect of the invention, This provides a photopolymer plate which has been F configured with a design produced by the above method.

PreFerably, a mould formed by a photopolymer plate in accordance with any of the above features of the second aspect of the invention. This provides a mould which has been configured using the above photopolymer plate and/or above method.

Brief Description of the Figures

FIgure 1 shows a cross-sectional view of the photopotymer mould manufacture.

Figure 2 shows a cross-sectional view of the back exposure of the photopolymer mould manufacture.

Figure 3 shows the main exposure of the photopolymer mould manufacture.

ao Figure 4 shows a cross-sectional view of the UY rays penetrating the photopolymer materiaL via the abtatable mask.

Figure 5 shows a cross-sectional view of the washing out of the unexposed photopolymer materiaL

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Figure 6 shows a cross-sectional view of the photopolymer mould having a post-exposure/finishing stage.

Detailed Description of the Figures

Figure 1 shows a cross-sectional view of a photopolymer mould, generally indicated by 1, which Incorporates a photopolymer plate 2. The plate incorporates a polyester base layer 3 arranged on a first side (bottom side) of the photopolymer pLate 2, which can be subsequentLy removed at a Later stage of the process. A laser abtatable mask (LAM) 5 is arranged on a second side (top side) of the photopolyrner place 2, which is also subsequently removed at a later stage in the process. A protection cover sheet 4 Is arranged on the top surface of the LAM 5.

Figure 2 shows a cross-sectional view of the back exposure of the photopolymer mould generally indicated by 1, whereby the protective cover sheet 4 has been removed from the LAM 5. An ultraviolet (UV) light source 11 is applied to the polyester base layer 3, which incorporates an array of UV light 12 that penetrates the polyester base 3 and hardens the photopolymer material to a depth indicated by a broken Line 13. This depth of hardened photopotymer material is known as the relief floor.

Figure 3 shows a cross-sectional view of the main exposure of the photopolymer mould, generally indicated by 1, whereby a laser imaging means has created an image, by creating an array of holes 23 within the LAM 5. A second UV light source 21 is applied to the tipper surface of the photopotymer mould 1, which incorporates an array of WV light 22 that are transmitted onto the LAM 5. The UV Light 22 is transmitted through the hoLes 23 wIthin the LAM 5, onto the exposed photopolymer plate material 2. The UV light 22 is cross-Linked in the exposed areas, thereby hardening the photopolymer material within the plate 2.

in an alternative embodiment, the polyester base Layer 3 is exposed to the liv light 22 that originates from the second WV light source 21, therefore hardening the photopolymer material to form the relief floor. The mould 1 is then rotated, typically by 180 degrees, which exposes LAM 5 to the Liv light 22. therefore both skies are exposed to UV Light 22 originating from the same Liv tight source 21.

Figure 4 shows a cross-sectional view of the main exposure of the photopolymer mould, which is generally indicated by 1, whereby the non-exposed portions of photopolymer material will determine the eventual recesses within the photopolymer mouLd 1. The UV rays 22 fran, the second UV Light source 21 harden the photopolymer material exposed by the array of holes 23, whIch define the image within the LAM 5. The unexposed photopolymer material 24 is not affected by the UV rays 22. and therefore remains in a to soft state. The UV rays 22 passing through the hoLes 23 within the LAM 5 form a shoulder 41, which defines the profile of the hardened photopolyrner material with respect to the portions of the unexposed photopotymer material 24. Each shoulder 41 wilt eventually define the profile of the recesses within the photopolymer material is The width of the portions of the LAM 5 determine the depth of the portions of unexposed regions within the photopolymer regions. he. the depth of the eventual recesses within the photopolymer material. The polyester base layer 3 is removed from the photopolymer plate 2.

Figure 5 shows a cross-sectional view of the washing out of the unexpased photopolymer material within the photopolymer mould which is generally indicated by 1. A brush 52 is arranged in paraLlel to the photopolymer plate 2, whereby the bristLes 51 of the brush 52 engage the photopolymer plate 2, The brush 52 is moved in an elliptical, circular motion, along a horizontal axis, which is generally indIcated 53, 54 and 55. The movement of the brush enables the brush to wash out all of the soft unexposed photopolymer materiaL 7 therefore leaving an array of recesses, which co-operate with the original image data, within the photopolymer plate 2. Once washed, the phot.opolymer mould is then aIr-dried.

Figure 6 shows a cross-sectional view of the washed out photopolymer mould 1, which Is so exposed (post-exposure) to a second exposure to the UV rays 22 from the second UV Light source 21. The post-exposure hardens the mould further, which eliminates any further tracks and any final cross-Linking 62.

The photopolyrner mould manufacturing process Incorporates the following steps: i0 1. remove the protective cover sheets; 2. laser imaging 3. back exposure; 4. main exposure; 5. wash out; 6. drying; 7. post-exposure/finishing.

iv The Laser imaging produces a "negative' on the LAM (laser ablatable mask), simPer to burning a fi'm on a plate but with much greater detail and image quality.

The drying process is provided by a hot air process, Le. fanassisted or another means of removing the washing solution/product from the mould such as compressed air infrared iz Light source or the like, ft is essential that the photopotymer mould provides high quahty images and texts, which comprises: 1. maximum image size of 2m x i,3m; 2. maximum image relief 6mm; 3. a high resolution image with a screen resolution of between 40 and 300 lines per inch.

A method of casting concrete with a metal finish comprising the steps of; creating a mould; mixing concrete incorporating metal powders introducing concrete into the finished mould; curing the concrete; removing the concrete from the mould; finishing the concrete surface.

The ingredients for the concrete including cement powder, metal powders and aggregates are blended together with water and concrete additives (eg. Plasticisers, viscosity modifying agents (VMAs) hydration accelerants) which are mixed to achieve the required consistency and viscosity. The use of plasticisers and viscosity modifying agents enables a concrete to be produced which is essentially a colloidal system containing powdered metal in the disperse phase within a continuous phase (or dispersion medium). The concrete Is applied directly onto the mould such that it spreads into the whole mould and air bubbles and/or spaces are removed. The flowability of the concrete Is such that the concrete spreads, or cart be spread, into the mould to remove as many air pockets as practicable and/or possible. The concrete products may be strengthened using reinforcement such as provided by steel reinforcement bars or, alternatively, glass fibre reinforcement may be added to the concrete prior to the concrete being poured into the mould.

Metal powders include tin, bronze, brass, copper.

Metallic products may be subsequently patinated using various chemical and heat treatments which are already known, particular within the casting of metal sculptures. F Concrete mix Our mix is typically between 1.25:1 and 2.5:1 metal powder to cement ratio by weight (the ratio is typIcally 2:1), water content is between 30-35% water to cement by weight.

Piasticiser, hydration accelerants and viscosity modifying agents are typically 2-10% of cement by weight. An acceterant is preferably added to initiate & accelerate the hydration of the concrete.

Mixing -the ingredients are added together and the concrete mixture Is mixed together using a high speed shearing action which ensures the Ingredients are well mixed. The mix is Ideally continuously agitated as It Is bring poured to maintain its flowabitity and ensure the concrete flows into all areas of the mould.

The addithi'es we are using for the metal concretes are a) polycarbo,late ether polymer superptasticlsers so b) high-molecular weight synthetic copotymer viscosity modifying agent c) hydration acceterants Polvcarhoxvtate ether poLymsucerpiasticLtrs A typicaL high water redudng p[asticiser are those in the Glenium ACE (TM) range of products manufactured by BASF (TM).

A typical viscosity modifying agent are those in the RheoMatrix (TM) range of products manufactured by BASE (TM).

fiymtIon accelernt.

to A typical hardening accelerator are those in the Xseed (TM) range of products manufactured by BASE (TM).

n an alternative embodiment of the invention, a vibrating means is attached or applied to the mouid mouLd after the metaL powder and concrete mix has been arranged within th:e mouLd. Therefore, facilitating the removal of air pockets and/or bubbles witHn the decorative surface of the cast, thereby providing a soiid and upitted surface that is ready for finishing.

Claims

CLAIMS1. A method of casting a concrete to form a product with a metal finish comprising the steps of: s Mixing a metal powder into a concrete; * Arranging said metal powder and concrete mix in a mould; * Setting said metal powder and concrete mix within said mould to form said product; * Removing said product from said mould; and * Finishing the surface of said product.
2. A method according to cLaim 1. wherein said concrete Is a colloidal system comprising said metal powder in a dispersed phase within a continuous medium.
3. A method according to either of the preceding claims, wherein said metal powder and concrete mix further comprises a 125:1 to 2.5:1 metal powder to cement ratio by weight.
4. A method according to claim 3. wherein said metal powder and concrete mix further comprises a 2:1 metal powder to cement ratio by weight
5. A method according to any of the preceding claims, wherein said metaL powder and concrete mix further comprises a water content of 30% to 35% water to cement by weight
6. A method according to any of the preceding claims, wherein said metaL powder and concrete mix further comprises a plasticiser and a viscosity modifying agent (VMA) of 2% to 10% of cement by weight
7. A method according to any of the preceding claims, wherein said mixing of metal so powder into concrete employs a high speed shearing means F
8. A method According to any of the proceeding claims, wherein said concrete mix is a self-Levelling concrete mix which provides flow and degassing properties.
9. A method according to any of the preceding claims, wherein said metal powder and concrete mix further comprises: * Polycarboxylate ether polymer superplasticisers and/on * High-motecular weight synthetic copolymer viscosity modifying agent and/or * Hydration acceleranes 10. A method according to claim 9, wherein said Polycarboxylate ether polymer superpiasticise6 Is a Clenium (TM) product from BASF (TM); High-molecular weight synthetic copolymer viscosity modifying agent is a RheoMATRIX product from BASF (TM) and Hydration accelerant is a)C-SEED (TM) from BASF.
10. A method according to any of the preceding claims, wherein said metal powder and concrete mix further comprises a reinforcement eLement. *1
11. A method according to any of the preceding claims, wherein said metal powder is: * Tin and/on * Bronze and/or * Grass and/or; * Copper.
12. A method according to any of the preceding claims, comprising the step of arranging a second metal powder and concrete mix in said mould, which comprises a lower metaL powder to cement ratio by weight than said first metal and concrete mix.
13. A method according to any of the preceding claims wherein said product Is a relief.
14. A method according to any of the preceding claims wherein said mould further comprises a photopotymer plate.so
15. A method of providing a photopolymer plate comprising the steps of: * arranging a backing Layer on a first side of a photopolymer plate: * arranging a masking layer on a second side of said photopotyrner plate; * using a laser to form a plurality of holes within said masking layer; * exposing portions of material in said photopolymer plate, which are exposed by said holes to an Ultra Violet (UV) light source, thereby hardening said portions of photopolymer plate that correspond with the width of each said hole; and * Removing the unexposed portions of photopotymer materiaL to form recesses on the photopotymer plate.
16. A method according to claim 15, wherein a first said hole and a second said hole comprise different widths.
17. A method according to either of the preceding claims, further compilsing the step of arranging a removable protective sheet on a side of said masking layer which is opposite said photopolymer plate.
18. A method according to any of the preceding claims, wherein said masking Layer is an ablatable layer, whereby said laser forms said plurality of holes therein.
19. A method according to any of the preceding claims, wherein said backing layer is formed from a removable polyester Layer.
20. A method according to any of the preceding claims, further comprising the step of exposing said backing layer to a second UV light source, thereby hardening said first side of said photopotymer plate to form a reVel floor.
21. A method according to claim 20, wherein said backing Layer is exposed to said second UV tight source for a predetermined time period.
22. A method according to any of the preceding claims, wherein said UV light source comprises a plurality of UV light emitting elements, whereby the emitted UV light so from a first said UV element overlaps with the emitted liv light from a second said UV element.
23. A method according to any of the preceding claims, further comprising the step of forming a wall of said hardened photopotyrner material about a portion of unexposed photopolymer materiaL
24. A photopotymer plate In accordance with any of the preceding claims.
25. A mould formed by a photopotymer plate in accordance with any of the preceding claims.
26. A method of casting a concrete to form a product with a metal finish as substantially hereinbefore described and/or Illustrated in any appropriate combination of the accompanying text and/or Figures.
27. A method of providing a photopolymer plate as substantially herelnbefore described 18 and/or illustrated in any appropriate combination of the accompanying text and/or Figures.