GB1585495A

GB1585495A - Metallized plastics strips

Info

Publication number: GB1585495A
Application number: GB19355/77A
Authority: GB
Original assignee: Protective Treatments Inc
Current assignee: Protective Treatments Inc
Priority date: 1976-05-10
Filing date: 1977-05-09
Publication date: 1981-03-04
Also published as: CA1079773A

Description

(54) METALLIZED PLASTIC STRIPS (71) We, PROTECTIVE TREATMENTS, INC., a Corporation organised nder the laws of the State of Ohio, United States of America, of 3345 Stop Eight Road, Dayton, Ohio 45414, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to metallized plastics strips useful as decorative trim strips which present a metallic appearance and which are,- longitudinally bendable without disrupting the thin metallized film which is relied upon to provide the desired metallic appearance.

Decorative trim strips comprising a plastics body portion bonded to a layer of transparent plastics material (usually polyethylene terephthalate) having a metallic film on one surface thereof to provide a metallized appearance are known. This composite strip of a plastics body portion and a metallized layer is enclosed or encapsulated within a sheath of a transparent plastics material to provide the final decorative trim strip, the metallized film being visible through the transparent sheath. Encapsulation is achieved by extruding a sheath of molten transparent plastics material about the composite strip described above, forming a continuous trim strip which simulates in appearance a conventional chrome or stainless steel trim strip and has similar functional and decorative utility. In this conventional practice, the plastics body portion is massive, the metal film is laterally configured in the composite strip as it goes through the extruder, and this lateral configuration is not changed thereafter.

It would be desirable if a thin and flat metallized composite strip could be encapsulated to form a thin extrusion. It would be particularly desirable if this thin extrusion could be laterally formed to a desired permanent nonplanar cross-section. Unfortunately, the thin, flat composite metallized strips which are at present available in commerce are unable to withstand the conditions encountered within the extruder; for example, when one attempts to extrude a hot melt of transparent polyvinyl chloride around the thin flat metallized compoiste. More particularly, the conventional available thin metallized composite strip comprises an aluminium film vapour deposited upon a thin layer of polyethylene terepthalate having a thickness of about 0.0005 inch, the metallized film being protected by a layer of pigmented polyvinyl chloride having a thickness of about 0.006 inch, and when the hot polyvinyl chloride encapsulant is extruded around this composite metallized strip, the metal film delaminates, wrinkles and bunches up and is rendered unsightly. The conventional available polyethylene terephthalate film which is metallized is as thin as possible because it is so expensive, and cannot itself sustain the tensile forces necessary to pull it through the extruder without stretching by more than the 12% or thereabouts which is the maximum elongation which can be tolerated before the metal film delaminates. Since the metal film is very thin, normally less than 25 microns in thickness, it cannot resist the tensile stress.

The problem of wrinkling and bunching of the metallic film in the extruder is not encountered in the ordinary production of decorative trim strips because the metallized polyethylene terephthalate is backed up by a massive plastics backing or body portion but the resulting extrusion is thick and rigid and, particularly after lateral curving, is of poor longitudinal bendability.

It has now been found that if at least the metal film surface of the metallized polyethylene terephthalate is coated or lamnated to a plastics support layer having sufficient thickness to prevent the polyethylene terephthalate from being excessively stretched when it is pulled through the extruder, the metal film does not bunch up or wrinkle and retains its attractive uniformly reflective appearance.

According to one aspect of the invention a method of producing a longitudinally bendable reflective encapsulated metallized extrusion comprises: feeding to an extruder a flat metallized composite strip constituted by a metal film having a thickness less than 25 microns deposited upon a layer of transparent plastics material incapable of sustaining the tensile forces used to pull the metallized composite stdip through the extruder without stretching to cause the metal film to delaminate, and a support layer of pigmented plastics material bonded to the metal film and having sufficient thickness to prevent the transparent plastics layer from such stretching, where by delamination of the metal film is avoided as the composite strip passes through the extruder; feeding molten transparent plastics material to the extruder, withdrawing from the extruder a hot encapsulate of the metallized composite strip within a sheath of hot transparent plastics material; and cooling the hot encapsulate to cause its shape to be permanently retained.

In one form of the invention a method of producing a laterally bent and longi tudnally bendable reflective encapsulated metallized extrusion comprises: feeding to an extruder a metallized composite constituted by a support layer of pigmented plastics material having a thickness in the range from 0.010 inch to 0.050 inch bonded to a layer of transparent plastics material having a metal film coating with a thickness less than 25 microns on the face thereof bonded to the support layer; feeding molten transparent plastics material to the extruder; withdrawing from the extruder a hot encapsulate of the metallized composite strip within a sheath of hot transparent plastics material; laterally bending the hot encapsulate to provide a nonplanar crosssection; and cooling the hot encapsulate to cause the nonplanar cross-sectiqn to be permanently retained.

According to another aspect of the invention a laterally bent and longitudinally bendable reflective extrusion comprises a composite metallized strip encapsulated in a sheath of transparent plastics material, the composite metallized strip comprising a film of metal having a thickness of less than 25 microns sandwiched between and bonded to a layer of transparent plastics material and a layer of pigmented plastics material and the sheath containing the composite metallized strip being permanently laterally curved.

The encapsulated metallized extrusions of this invention may be stretched considerably when longitudinally bent which would cause some delamination in use. This would damage a conventional laminated strip because moisture could then reach the metal film to cause it to deteriorate. However, moisture is excluded in the encapsulated extrusion of the present invention, so such delamination can be tolerated.

In preferred practice, it has been found that by employing a pigmented polyvinyl chloride support layer bonded to the metal film, the support layer having a thickness in the range from 0.010 to 0.050 inch, and desirably not in excess of 0.030 inch, the prior art problems of melting, sagging, wrinkling, buckling and delamination are avoided despite the thinness of the transparent plastics layer on which the metal film is deposited; the resulting encapsulated metallized composite strip can be laterally configured before it hardens, and is still longitudinally bendable without appreciable disfigurement of the metal film.

In the practice of this invention, the composite metallized strip comprising a film of metal sandwiched between the pigmented layer and the thin transparent layer is pulled through an extruder to apply a sheath of transparent molten plastics material entirely around the composite metallized strip to form a thin hot encapsulate. The molten plastics material is preferably polyvinyl chloride. The thin encapsulated composite strip may be laterally shaped while hot, and then cooled to cause it permanently to retain the shaped nonplanar cross-section.

The metallized film is very thin and has little strength of its own having a maximum thickness of less than 25 microns, usually less than 3 microns.

In preferred practice, the metallized composite strip is fed through a conventional extruder having, for example, a cross-head extrusion die through which the composite strip is supported and guided by a nose piece located as close to the exit aperture of the extruder as is convenient, to minimize the thermal impact upon the composite strip which is encapsulated.

Molten thermoplastic material is f6d into the extruder, preferably as near to the exit end of the extruder as possible, again to minimize thermal impact. The extruded product emerges hot from the extruder in a generally flat condition (or a portion of it is flat) and is drawn through a forming zone where it is laterally bent to provide a thin strip of nonplanar cross-section.

More particularly, the flat product is laterally bent to form a curve, with the metal film visible through a convex portion of the curve. It is preferred that the metal film be in tension in the curved product.

The forming zone of the extruder is desirably contained in a cooling zone so that lateral bending or shaping is coupled with some hardening of the thin encapsulated composite strip into the nonplanar cross-section. The product is then further cooled so that the nonplanar cross-section is permanently retained.

The resulting shaped encapsulated composite metallized strip is longitudinally bendable without disfiguring the metallized film, so it can be used for decorative purposes where longitudinal bending is necessary.

The invention may be performed in various ways, and some embodiments will now ibe described by example with reference to the accompanying drawings, wherein: Figure 1 is a fragmentary cross-section of a composite metallized strip for use in making an extrusion according to the invention; Figure 2 shows a drip rail made from an extrusion according to the invention mounted above and beside a door of a truck; Figure 3 is a cross-section of the drip rail taken along the line 3-3 of Figure 2; Figure 4 shows in solid lines the crosssection of a T-section locking strip as extruded, and broken lines the shape of the strip after it has been laterally bent; Figure 5 is a cross-sectional view of the locking strip of Figure 4 after it has been longitudinally bent and mounted between a drip rail and a window; Figure 6 is a view of the locking strip mounted above the quarter window of an automobile; and Figure 7 is a diagramamtic view of one method embodying the invention of producing laterally bent and lonigtudinally bendable extrusions.

Referring to Figure 1 of the drawings, the composite metallized strip 10 comprises a reflective metal film 12 sandwiched between a light-transmissive fluid-impervious thin plastics layer 14 and a thicker plastics support layer 16. The composite metallized strip 10 can be used in various extrusions embodying the invention, such as a decorative trim strip, or a drip rail 18 as shown in Figure 3 or a T-section locking strip 20 as shown in Figure 5.

The reflective metal film 12 is constituted by a multitude of flakes or particles, such as aluminium particles, vapour deposited on, or otherwise bonded to, the thin plastics layer 14. The metal film 12 is less than 25 microns thick, the usual thickness being less than 3 microns. The metal film has little strength of its own, and it has generally planar surfaces 22 and 24. Vapour deposited aluminium having a thickness of about 2 microns is used in the embodiments of the invention illustrated.

The layer 14 is of clear, light-transmissive plastics material to enable the metal film to be seen through the layer, but since it is so thin it alone cannot adequately sustain the tension encountered within the extruder.

As shown in Figure 1, the layer 14 is thinner than the support layer 16; it is less than 0.001 inch in thickness to minimize its cost. In the illustrated form of the invention, polyethylene terephthalate with a thickness of 0.0005 inch is used. The layer 14 has an outer surface 26 and an inner surface 28. The inner surface 28 is coextensive with and bonded to the planar surface 22 of the metal film 12.

The support layer 16 overlies the second planar surface 24 of the metal film 12 and may be opaque. In the embodiment illustrated, the support layer is of blackpigmented polyvinyl chloride having a thickness of 0.012 inch. The support layer 16 has a surface 30 bonded to the metal film and an exterior surface 32.

Molten thermo-plastics material surrounds the metallized strip 10 during extrusion to form a thin sheath around it. The term "thin" here denotes easy bendability with finger pressure. Usually the sheath thickness will be in the range from 0.04 inch to 0.3 inch.

On the one hand the support layer 16 is of sufficient thickness and strength to withstand the extrusion forces at the elevated extrusion temperatures so that the composite metallized strip 10 is not unduly stretched while it is being pulled through the extruder. This prevents buckling, breaking-up and bunching of the metal film in the extruder. On the other hand the support layer 16 is sufficiently thin to accommodate lonigtudinal bending and flexing of the finished product after encapsulation, lateral shaping and cooling. For pigmented polyvinyl chloride the support layer 16 has a thickness of at least 0.010 inch when transparent polyvinyl chloride is the encapsulating resin. The thickness of the pigmented polyvinyl chloride should preferably not exceed 0.050 inch. The preferred thickness range of the pigmented polyvinyl chloride layer 16 is from 0.012 inch to 0.030 inch. For some types of extrusion products, it is desirable to keep the thickness of the polyvinyl chloride support layer 16 as small as possible within the preferred range, preferably about 0.012 inch, to maximize the flexibility of the product. Preferably, the hardness of the polyvinyl chloride support layer 16 is about 49+5 Shore hardness (D scale using the 15 second delay method).

The composite metallized strip 10 may be used in producing a laterally bent and longitudinally bendable encapsulated metallized extrusion product, such a Jsection drip rail 18 as shown in Figure 3.

The J-section drip rail has an elongate sheath 34 of light-transmissive fluidimpervious thermoplastic, such as transparent polyvinyl chloride, with exterior surfaces 35 and 37. The J-section is constituted by an upright portion 36 and a hooked portion 38. The back surface 40 of the upright portion 36 is coated with a pressure sensitive adhesive 42 which is normally covered with a peelable paper backing prior to use. When it is desired to secure the drip rail to the exterior surface 44 of a truck as shown, the paper backing is peeled off and discarded. - The upwardlyfacing surface 46 of the hooked portion 38 defines a gutter for receiving and channelling water. The sheath 34 thermoplastically encapsulates the composite metallized strip 10 with the exterior surface 32 of the support layer 16 facing the sheath's exterior surface 35 and the light-transmissive fluidimpervious layer 14 facing the sheath's exterior surface 37 so that the reflective metal film 12 can be seen through the exterior sufrace 37. As shown in Figure 2, the drip rail can be longitudinally bent and fixed above and beside the door 50 of a truck 52 to catch falling rain water or melting snow and channel the water to the roadway.

The composite metal strip 10 is also useful in forming a laterally bent and longitudinally bendable extrusion product such as a T-section locking strip 20 (see Figure 5) for mounting about the quarter window 54 of an automobile 56. When installed, the T-section locking strip serves as a decorative trim as well as a weather strip. As shown in solid lines in Figure 4, the T-section locking strip 20 is initially formed in the extruder with a thermoplastic sheath 58 of trtansparent or translucent plastics material, such as clear nonpigmented polyvinyl chloride. The sheath 58 envelops the metallized strip to form a metallized portion 60 and a cross-portion 62 extending therefrom. The metallized strip 10 is encapsulated with the metal film 12 facing away from the cross-portion 62 so that it can be seen from the front or top surface 63 of the locking strip as shown in Figure 5. The T-section locking strip 20 is laterally bent as shown in broken lines in Figure 4, and it can later also be bent longitudinally as shown in Figure 6 to enable mounting about the window 54. In the embodiment shown in Figure 5, the cross-portion 62 overlies the hooked portion of a drip rail 18'. The end 61 of the metallized portion 60 is wedged between the window 54 and the drip rail 18'. The other metallized portion having the surface 63 overlies the window 54.

In Figure 7, the composite metallized strip 10 is fed into an extruder 66, such as a cross-head extrnusion die. In the embodiment illustrated, the composite metallized strip 10 is supported and guided by a nose piece positioned in the rearward section of the extruder 66. Simultaneously, molten thermoplastic material, such as clear nonpigmented polyvinyl chloride, is fed into the extruder at 68. The molten thermoplastic intimately contacts and enscapsulates the composite metallized strip 10 near the exit of the cross-head extrusion die so as to minimize thermal impact. The extrusion die has an internal contour conforming to a preselected cross-sectional shape of the generally flat extruded product 70. For the J-section composite drip rail 18 the internal contour of the extrusion die is shaped so that the extruded product emerges hot from the extruder in a generally flat condition. For the locking strip 20, the extruded product emerges hot from the extruder in a T-section configuration substantially as shown in solid lines in Figure 4, with the metallized portion 60 substantially flat.

The hot, pliable, extruded encapsulate 70 upon emerging from the extruder 66 is drawn through a forming zone 72 generally defined by water-cooled plates or blocks 74 having a water inlet 76 and a water outlet 78. In the forming zone the extruded product is laterally bent and cooled. The internal contour or passageway of the water-cooled plates or blocks changes progressively until it conforms to the ultimate nonplanar cross-sectional shape of the laterally bent extruded product 80. For example, the drip rail is laterally bent to a J-section in the forming zone, whereas the locking strip is laterally bent in the forming zone so as to take on the configuration shown in Figure 5. The laterally bent extruded product emerges from the watercooled plates or blocks 74 in a warm condition and is drawn through a final cooling zone 82, such as a water trough, where the product is cooled and hardened so that the imparted cross-section is permanently retained. In a preferred embodiment the cooling zone is part of the forming zone.

The resultant laterally bent and hardened extrusion product 64 is longitudinally bendable without disfiguration or delamination of the composite metallized strip 10.

While polyvinyl chloride is of especial value in performing the present invention it can be replaced by other similar resins, such as polyvinylidene chloride or cellulose acetate butyrate. The transparent plastics layer on which the metal film is deposited is preferably clear, very strong for its thickness, and resistant to high temperatures. Polyethylene terephthalate is outstanding for this purpose but other plastics having similar characteristics, such as polyamides, may be used.

While the illustrated products have involved the preferred lateral bends in which the metallized portion faces the convex surfaces, the metallized portion could face concave surfaces, and the method of the invention also includes the formation of flat extrusions.

WHAT WE CLAIM IS:- 1. A method of producing a longitudinally bendable reflective encapsulated metallized extrusion comprising: feeding to an extruder a flat metallized composite strip constituted by a metal film having a thickness less than 25 microns deposited upon a layer of transparent plastics material incapable of sustaining the tensile forces used to pull the metallized composite strip through the extruder without stretching to cause the metal film to delaminate, and a support layer of pigmented plastics material bonded to the metal film and having sufficient thickness to prevent the transparent plastics layer from such stretching, whereby delamination of the metal film is avoided as the composite strip passes through the extruder; feeding molten transparent plastics material to the extruder, withdrawing from the extruder a hot encapsulate of the metallized composite strip within a sheath of hot transparent plastics material; and cooling the hot encapsulate to cause its shape to be permanently retained.

2. A method as claimed in Claim 1 in which the sheath has a cross-portion extending therefrom.

3. A method as claimed in Claim 1 or Claim 2 for producing a laterally bent and longitudinally bendable reflective encapsulated metallized extrusion, comprising laterally bending the encapsulate to provide a nonplanar cross-section before or while cooling it.

4. A method as claimed in Claim 3 in which the encapsulate is laterally bent to a curved cross-section with the metal film visible through a convex portion of the curve.

5. A method as claimed in Claim 2, or in Claim 3 or Claim 4 as dependant on Claim 2, in which the lateral bending includes bending the cross-portion.

6. A method of producing a laterally bent and longitudinally bendable reflective encapsulated metallized extrusion comprising: feeding to an extruder a metallized composite strip constituted by a support layer of pigmented plastics material having a thickness in the range from 0.010 inch to 0.050 inch bonded to a layer of transparent plastics material having a metal film coating with a thickness less than 25 microns on the face thereof bonded to the support layer; feeding molten transparent plastics material to the extruder; withdrawing from the extruder a hot encapsulate of the metallized composite strip within a sheath of hot transparent plastics material; laterally bending the hot encapsulate to provide a nonplanar cross-section; and cooling the hot encapsulate to cause the nonplanar cross-section to be permanently retained.

7. A method as claimed in Claim 6 in which the lateral bending is accompanied by cooling.

8. A method as claimed in any of the preceding Claims in which the support layer is pigmented polyvinyl chloride, the transparent layer is polyethylene terephthalate and the molten transparent plastics material is polyvinyl chloride.

9. A method as claimed in any of the preceding Claims in which the thickness of the transparent layer is less than 0.001 inch.

10. A method of producing longitudinally bendable reflective encapsulated metallized extrusions, substantially as described with reference to Figure 7 of the accompanying drawings.

11. Longitudinally bendable reflective encapsulated metallized extrusions which have been produced by a method as claimed in any of the preceding Claims.

12. A laterally bent and longitudinally bendable reflective extrusion comprising a composite metalized strip encapsulated in a sheath of transparent plastics material, the composite metallized strip comprising a film of metal having a thickness of less than 25 microns sandwiched between and bonded to a layer of transparent plastics material and a layer of pigmented plastics material, and the sheath containing the composite metallized strip being permanently laterally curved.

13. An extrusion as claimed in Claim 12 in which the sheath is curved so that the metal film is positioned to be visible through a convex portion of the curve.

14. An extrusion as claimed in Claim 12 or Claim 13 in which the pigmented layer is pigmented polyvinyl chloride, the layer of transparent plastics material is polyethylene terephthalate, and the sheath is formed of clear polyvinyl chloride.

15. An extrusion as claimed in Claim 14 in which the polyethylene terephthalate layer has a thickness of less than 0.001 inch and the pigmented polyvinyl chloride layer has a thickness in the range from 0.010 inch to 0.050 inch.

16. An extrusion as claimed in Claim 15 in which the pigmented polyvinyl chloride layer has a thickness of less than 0.030 inch and the sheath has a thickness in the range from 0.04 inch to 0.3 inch.

17. An extrusion as claimed in any of Claims 12 to 16, useful as a drip rail, in which the sheath containing the composite

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. While the illustrated products have involved the preferred lateral bends in which the metallized portion faces the convex surfaces, the metallized portion could face concave surfaces, and the method of the invention also includes the formation of flat extrusions. WHAT WE CLAIM IS:-

1. A method of producing a longitudinally bendable reflective encapsulated metallized extrusion comprising: feeding to an extruder a flat metallized composite strip constituted by a metal film having a thickness less than 25 microns deposited upon a layer of transparent plastics material incapable of sustaining the tensile forces used to pull the metallized composite strip through the extruder without stretching to cause the metal film to delaminate, and a support layer of pigmented plastics material bonded to the metal film and having sufficient thickness to prevent the transparent plastics layer from such stretching, whereby delamination of the metal film is avoided as the composite strip passes through the extruder; feeding molten transparent plastics material to the extruder, withdrawing from the extruder a hot encapsulate of the metallized composite strip within a sheath of hot transparent plastics material; and cooling the hot encapsulate to cause its shape to be permanently retained.

metallized strip is permanently laterally curved adjacent one edge thereof to form a hooked portion in which the metal film is visible through the convex surface of the hooked portion, and the rest of the sheath is planar.

18. An extrusion as claimed in Claim 17 in which the planar portion of the sheath carries a pressure-sensitive adhesive on the side thereof remote from the hooked portion.

19. An extrusion as claimed in any of Claims 12 to 16, useful as a locking strip, in which the sheath containing the composite metallized strip is permanently laterally curved adjacent one edge thereof to form a front portion of the locking strip in which the metal film is visible through the convex surface of the front portion, and the sheath Las a laterally curved cross-portion extending therefrom.

20. A lonigtudinally bendable reflective encapsulated metallized extrusion substantially as described with reference to any of Figures 2 to 6 of the accompanying drawings.