DE102021202752A1 - BLOW-EXTRUDED ROAD SIGN - Google Patents

Abstract

Traffic sign designed as a blow-moulded traffic sign with a hollow body made of plastic. The hollow body is provided with a reflector film on at least one side wall, which has a light-reflecting layer facing away from the hollow body. The reflector film also has a separator layer which faces the side wall of the hollow body and is firmly connected to the light-reflecting layer.

Description

The invention relates to traffic signs that are designed as blow-molded traffic signs and have a hollow body made of plastic that is produced in a blow-molded extrusion process. The invention relates, for example, to beacons, warning signs, barriers and anti-fall devices, such as are used to secure construction sites and other hazardous locations.

Such beacons, fall protection devices and/or barriers are known from the prior art, the base body, which carries a retroreflective reflector film, usually being a blow-molded hollow body made of plastic, preferably made of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), Polyamide (PA), polyphenylene oxide (PPO), acrylonitrile butadiene styrene (ABS) or a polymer blend. Such a barrier describes, for example EP 1 388 612 B1 , in which the barrier blade is formed by a blow molding made of plastic. In a processing step of the hollow body that follows the blow extrusion process, the retroreflective reflector film must be applied to the blow molding made of plastic produced in this way in the blow extrusion process. In the prior art, this has hitherto been done by gluing on such a retroreflective reflector film, with self-adhesive films often being used here.

However, a film, in particular a retroreflective reflector film, cannot be applied to the hollow body produced in the blow extrusion process immediately after blow extrusion, since blow-moulded plastics have a non-polar, electrically well insulating and water-repellent surface. This is poorly wettable by adhesives or adhesion promoters. This applies above all to the pasting of polyethylene, polypropylene and polyester films. Corona treatment - the most commonly used form of surface treatment - is helpful here, in which the film web and/or the surface of the blown body (hollow body) is exposed to a high-voltage electrical discharge. Alternative methods are flame treatment, fluorination and plasma treatment of the surface(s) to be bonded. The goal of all these methods is to increase the polarity of the surface, which significantly improves wettability and chemical affinity. But also leaving it alone, during which the blow-molded plastic can "outgas", as the expert describes the time during which it is not possible to stick a reflector foil on, or during which the reflector foil would at least partially detach from the hollow body after sticking on, leads to a surface of the hollow body that can be glued. However, allowing the blown body to rest ("outgassing") takes a few days to weeks, depending on the wall thickness and component size and the plastic used.

The object of the invention is therefore to provide a method of avoiding this waiting time or other surface treatments of the film to be stuck on and how blow-molded hollow bodies to be provided with a traffic sign, in particular with a retroreflective reflective film, can be produced more easily and cost-effectively in a shorter time. The production process according to the invention should be simple and robust in its design and should also make it possible to produce reliable, robust traffic signs with a blow-molded hollow body provided with a retro-reflective reflector film in a short production time and in large quantities.

According to the invention, this object is achieved by a traffic sign according to claim 1 and a method for producing such a traffic sign according to claim 12, preferred embodiments being specified in the respective dependent subclaims.

The traffic sign according to the invention is designed as a blow-molded traffic sign with a hollow body made of plastic, with the hollow body being provided with a retro-reflective reflector film on at least one side wall. This retro-reflective reflector film has a layer facing away from the hollow body, which retro-reflects incident light, ie, reflects (back) the incident light essentially in the direction of incidence. Compared to the traffic signs known from the prior art, the traffic sign according to the invention is characterized in that the reflector film has a separator layer which faces the side wall of the hollow body and is firmly connected to the light-retroreflective layer Hollow body is connected.

According to the invention, the retro-reflector film is attached to the hollow body as early as during blow molding, which means that the conventional gluing step carried out in the prior art can be omitted. With the elimination of the gluing step, the pretreatment of the hollow body and/or the reflector foil, or the waiting time that has to be waited until a foil can be applied to a blow-molded hollow body by means of an adhesive, is also eliminated. The retro-reflector film is preferably placed in the blow mold before the plastic preform is introduced into the blow mold. After the plastic parison has been placed in the blow mold, it is inflated in the heated state and so during the inflation of the parison Reflector foil with the hollow body materially connected in the manner of in-mold labeling.

A plastic suitable for a hollow body of a traffic sign is, for example, polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyamide (PA), polyphenylene oxide (PPO), acrylonitrile butadiene styrene (ABS) or a polymer blend. Therefore, the separator layer used according to the invention must have a suitable material on the rear side of the retro-reflector film that forms a material connection with the material of the hollow body when the preform is blown up in the blow mold. In a preferred embodiment, the material of the separator layer is similar to the material of the hollow body or even the same.

When the retro-reflector film with separator layer is introduced into the blow mold according to the invention, the reflector side of the reflector film comes into contact with the shaping surface of the blow mold, so that the separator layer faces the cavity and can thus be connected to the expanding hollow body, in particular with a material bond. After removing the traffic sign according to the invention with a blow-moulded hollow body made of plastic and a materially bonded reflector film as a traffic sign, it is almost ready for use as a fall protection device or beacon etc. after it has cooled down. Of course, further processing steps can be carried out immediately after the traffic sign has been removed from the blow mold, such as attaching or inserting stiffening components, stiffening tubes and/or receiving devices, such as pins for fastening the traffic sign in a base plate.

The retro-reflective foil used according to the invention is dimensioned before it is placed in the blow mold in such a way that after the hollow body has shrunk during the cooling time, it maintains the required retro-reflection values and the required reflection area. The person skilled in the art is aware that retro-reflection means that light incident on the film is reflected back essentially in the same direction. In order for the reflector foil used according to the invention to be able to fulfill the retro-reflection properties required as a traffic sign on the finished traffic sign, it can be enlarged with a shrinkage factor before it is placed in the blow mold, particularly in the case of large traffic signs such as fall protection or barriers, so that the final resulting reflector surface legal requirements are sufficient. A pre-stretching of the reflector foil can also be considered here, which loses its (pre-) tension during the cooling time of the traffic sign produced according to the invention.

Due to the inventive use of a reflector film with a separator layer, which enters into a material connection with the material of the hollow body during the blowing step in the production of the blow-molded hollow body, the wall thickness of the hollow body can have a smaller wall thickness on the side wall to which the reflector film is applied. as shown, for example, by side walls on which no reflective foil should be attached. Of course, the traffic sign according to the invention can have several such retro-reflective reflector films on different side walls of the hollow body. Furthermore, it is also conceivable that the reflector foil(s) placed in the blow mold according to the invention also carries a pictogram indicating a traffic law arrangement, which can also be designed in a retro-reflective manner.

The fact that with the method according to the invention not only reflector foils with a separator layer can be applied to the hollow body, but also a decoration or other foils with a corresponding separator layer, for example the company name, is also included in the idea of the invention. What all films have in common is that the separator layer forms a material bond with the material of the hollow body of the traffic sign. It is also conceivable for such a decorative film with a separator layer to have a relief on the decorative side which, for example, bears a trade name or the company name of the manufacturer/installer of the traffic sign.

According to the invention, the hollow body of the traffic sign is produced using the blow molding process known from the prior art. That is to say, in the extrusion step, in one exemplary embodiment of the invention, a plastic preform, for example tubular, is produced in such a way that it preferably dips directly into the blow mold, essentially vertically, at the outlet of the extrusion die. When the blow mold is closed, the internal pressure in the preform is then increased to form (inflate) the hollow body of the traffic sign, the separator layer of the reflector film being bonded to the hollow body without the use of any adhesive. The person skilled in the art is aware that this "blowing" of the hollow body takes place at elevated temperatures below the melting point at which the plastic used is easily plastically deformable. In this heated state, the plastic forms a tough mass, which molds the blow mold negatively by inflation, whereby the Hollow body is formed for the traffic sign. After expansion due to the increased internal pressure in the preform, the hollow body remains in the blow mold at least until the plastic has cooled down to such an extent that removal is possible without deformation. After the blow mold has been opened and the hollow body provided with a reflector film according to the invention or the traffic sign has been removed, it can be fed to a further processing step or used directly as a traffic sign.

In the production method according to the invention of a traffic sign provided with a reflector film, the reflector film is held together with the separator layer in the blow mold, for example by means of negative pressure or static charging, until the separator layer has bonded to the material of the hollow body. It may be necessary to apply a release agent to the shaping surface of the corresponding mold half of the blow mold before inserting the reflector film with separator layer or another decorative film with separator layer. Such a release agent can be sprayed on or represent a protective film or a protective layer on the reflector film, so that demoulding of the reflector film or the (additional) decorative film from the blow mold is made possible without damage. To shorten the cooling or curing time, the person skilled in the art has the usual means available, such as blowing in cooling air, for example through the hollow body, or by flushing the blow mold with cooling water or the like as measures customary in the art.

If the reflector film is held in the blow mold by means of negative pressure, for example, the negative pressure must be removed before the finished traffic sign is removed and, if necessary, switched to positive pressure so that the traffic sign can be removed. This can preferably be done using a handling device. Of course, in the case of a semi-automated or fully automated production of the traffic sign, the removal can also take place off the tool, in which case the person skilled in the art has to take into account the necessary prerequisites with regard to deformation, etc. here.

It goes without saying for a person skilled in the art that several reflector foils can also be attached in different areas of a hollow body, just as the blow mold can have several cavities for the simultaneous formation of several hollow bodies with reflector foils and/or decorative foils attached thereto according to the invention. Such multiple tools are known to the person skilled in the art from the prior art and are therefore included in the concept of the invention.

In the production according to the invention of a traffic sign with a blow-molded hollow body to which a reflective foil is materially bonded without the use of an adhesive, all types of reflective foils known from the prior art can be used. The light-retro-reflecting layer used can have prism-like structures embossed in the reflector film or it can be a film provided with glass beads. All known types of reflector films can be used here and—like conventional retro-reflector films—have, for example, a top-coat acrylic coating. However, the reflector film that can be used according to the invention must have a separator layer that is suitable for being bonded to the plastic of the hollow body in a materially bonded manner in the blow molding process.

• 1: schematisch eine erfindungsgemäße Bake;
• 2: eine Schnittdarstellung durch die in 1 gezeigte Bake;
• 3: eine Detailansicht der Schnittdarstellung aus 2;
• 4: schematisch eine Schnittdarstellung durch eine erfindungsgemäß verwendete Reflektorfolie;
• 5: eine erfindungsgemäß hergestellte Absperrtafel und eine erfindungsgemäß hergestellte Absturzsicherung;
• 6: ein Konvolut beispielhaft ausgewählter Verkehrsschilder, die mit dem erfindungsgemäßen Verfahren herstellbar sind;

For further explanation of the method according to the invention and for further explanation of preferred embodiments of traffic signs according to the invention, the following figures show, without limiting the inventive idea:

• 1 : schematically a beacon according to the invention;
• 2 : a sectional view through the in 1 shown beacon;
• 3 : a detailed view of the section view 2 ;
• 4 : a schematic sectional view through a reflector film used according to the invention;
• 5 : a barrier panel made according to the invention and a fall protection made according to the invention;
• 6 : a set of traffic signs selected by way of example which can be produced using the method according to the invention;

1 shows a beacon 10 according to the invention with a blow-molded hollow body 1 to which, according to the invention, a reflector film 3 is bonded by means of a separator layer 4 (not shown). In this exemplary embodiment, the reflector film 3 shows a left-pointing arrow. The reflector film 3 used here can be designed to be retro-reflective, for example by means of prisms or glass beads. The hollow body 1 as well as the (traffic) sign 10 and its color can be freely selected according to the invention and can therefore be adapted depending on the regulations for individual countries or to different purposes of use of the traffic sign. This is how the in 1 The beacon 10 shown has an arrow pointing to the left, which of course can also point to the right in another embodiment. Instead of directional In addition to arrows, the retro-reflective reflective foil can also show warning hatching, whereby reflective foils with other pictograms are used to represent traffic signs, e.g. for stop signs, left-turn arrows, pedestrian crossings, etc.

The two pins 6 are used to hold the beacon 10 in a base plate or to hold a warning light on the beacon 10. These pins 6 can be stiffened in a subsequent processing step and provided with a locking element, for example, the stability of the beacon 10 in a to raise the footplate.

2 shows a sectional view through a beacon 10 according to the invention, as shown, for example, in 1 is shown. It can be seen here that a reflector film 3 has been applied to each of the opposite side walls 2 of the hollow body 1 . According to the invention, this is done using the in-mold labeling process, so that the respective separator layers 4 (cf. 4 ) of the reflector foils 3 used are bonded to the side walls 2 of the hollow body 1 or even merge.

At the beacon 10 according to the invention you can, as in detail B of 3 recognizable, no clear material boundary between the material of the side walls 2 and the separator layers 4 can be seen, but a clear transition from the separator layers 4 to the light-reflecting layer 5. Thus, the thickness of the separator layer 4 together with the thickness of the side wall 2 forms the wall thickness of the Hollow body in the areas where according to the invention a retro-reflective reflector film 3 is formed in the in-mold labeling process.

4 shows a section through a reflector film 3 used according to the invention for a beacon 10 before it is placed in a blow mold. A separator layer 4 can be seen on the back of the reflector film 3, which is suitable for entering into a material bond with the material of the hollow body 1 of the traffic sign 10 during the blow molding step. The thickness of the separator layer 4 is in 4 shown thicker for better visibility than is required for the inventive attachment of the reflector film to the hollow body 11 . However, the thickness of the separator layer 4 should be at least so great that the retro-reflective layer 5 applied to one side of the reflective foil 3 remains permanently connected to the separator layer 4 and the retro-reflective layer 5 during the attachment of the reflective foil 3 in the blowing step of the blow -does not take any damage from being extruded. In reality, the separator layer 4 is about as thick or even thinner than the light-reflecting layer 5.

According to the invention, the reflector film 3 should have an oversize increased by the amount of shrinkage before the blow molding step is carried out during blow molding, so that the desired and/or required reflector surface remains on the traffic sign after the hollow body 1 has cooled. A stretched stretching of the reflector foil 3 in the blow mold can also be considered here, as well as a pre-stretching of the same. If, for example, a reflector foil 3 made up of glass beads is used, the oversize caused by shrinkage can be easily taken into account when cutting the reflector foil 3 to be inserted into the blow mold. However, something similar is also conceivable for prisms.

In 4 an optional top coat coating 7 is also shown, which forms the light-reflecting layer 5 together with the light-reflecting components, such as prisms or glass beads. This top coat coating 7 can be applied to protect the reflective foil 3 from damage when handling the reflective foil 3 before it is placed in the blow mold or after removal of the hollow body 1 provided with the reflective foil 3, so that the retro-reflective layer is not already is damaged by the use of the traffic sign. This top coat 7 is often an integral part of the reflector film 3 used according to the invention.

5 shows a barrier panel 10 produced according to the invention as well as a fall protection device 10 produced according to the invention with molded reflector foils 3, in each case in the upper and in the lower area. 5 shows clearly that the inventive molding of a reflector film 3 in the in-mould labeling process is not limited to the size of a traffic sign. At the same time as the reflective foils 3 are molded on, decorative foils 8 which, for example, show the name of the manufacturer or the person who installed the traffic sign, can also be molded on in the same way.

6 shows a selection bundle of possible traffic signs 10, with the method according to the invention in the 1 until 5 traffic signs shown can also be produced. All the in 6 The traffic signs 10 shown have a pin/foot 6 with which, after blow molding according to the invention, the traffic signs can be set up, for example by means of a base plate. A person skilled in the art will find a variety of other traffic signs here that are produced using the production method according to the invention can be provided. All of these are therefore also included in the concept of the invention.

Reference List

10

Traffic Sign / Traffic Sign

1

hollow body

2

Side wall

3

reflector foil

4

separator layer

5

light-reflecting layer

6

spigot / foot

7

Top coat coating

8th

Decorative film / decorative layer

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 1388612 B1 [0002]

Claims (22)

Traffic sign, designed as a blow-moulded traffic sign (10) with a hollow body (1) made of plastic, the hollow body (1) being provided with a reflector film (3) on at least one side wall (2), the one facing away from the hollow body (1) being light -reflective layer (5), characterized in that the reflector film (3) also has a separator layer (4) which faces the side wall of the hollow body (1) and is firmly connected to the light-reflecting layer (5), which is adhesive-free, is applied to the hollow body (1) in a cohesive manner by means of an in-mold process. traffic signs claim 1 , characterized in that the hollow body (1) is blow-extruded from polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyamide (PA), polyphenylene oxide (PPO), acrylonitrile butadiene styrene (ABS) or a polymer blend . traffic signs claim 1 or 2 , characterized in that the separator layer (4) comprises a plastic which is cohesively connected to the plastic of the hollow body (1) in the in-mold process. Traffic sign according to one of the preceding claims, characterized in that the side wall (2) of the hollow body (1) on which the reflector foil (3) is applied has a smaller wall thickness than in blow-molded traffic signs with reflector foil glued on. Traffic sign according to one of the preceding claims, characterized in that the reflector foil (3) bears a pictogram indicating an arrangement under traffic law. Traffic sign according to one of the preceding claims, characterized in that the traffic sign (10) is provided on a further surface with a further reflector film (3) and/or with a decorative film (8) which is bonded without adhesive using in-mold processes is formed onto the hollow body (1). traffic signs claim 6 , characterized in that the decorative film (8) has a relief. Traffic sign according to one of the preceding claims, characterized in that the hollow body (1) has at least one pin (6) arranged at one end for connecting the hollow body (1) to a floor or base plate. Traffic sign according to one of the preceding claims, characterized in that the light-reflecting layer (5) has embossed prism-like structures or is a film provided with glass beads. Traffic sign according to one of the preceding claims, characterized in that the light-reflecting layer (5) has a top-coat acrylic coating (7). Traffic sign according to one of the preceding claims, characterized in that the traffic sign (10) is a beacon, a warning sign, a traffic sign, a warning sign, a fall protection device or an information sign. Method for producing a traffic sign (10) designed as a traffic sign made of plastic by means of blow molding, the method having the following steps: - Inserting a reflector film (3) provided with a separator layer (4) in at least one mold half of an opened blow mold in such a way that the separator layer (4) faces away from the shaping surface of the mold half; - Extruding and introducing a tubular plastic parison into the blow mold; - closing the blow mould; - Increasing the internal pressure in the preform to form a hollow body (1) of the traffic sign (10) and bonding the reflector film (3) to the hollow body (1) without adhesive and in a materially bonded manner; - Allowing the traffic sign (10) to cool in the blow mold until it has sufficient strength for removal; - Opening the blow mold and removing the hollow body (1) provided with the reflector foil (3); procedure after claim 12 , in which the reflector foil (3) is held in the blow mold by means of negative pressure or static charging. procedure after claim 12 or 13 , in which a further reflector film (3) and/or decorative film is additionally inserted into the blow mold before the preform is extruded and introduced into the blow mold. Procedure according to one of Claims 12 until 14 , in which before inserting the reflector film (3) and / or the decorative film, a release agent is applied to the corresponding mold half. Procedure according to one of Claims 12 until 14 , in which the reflector film (3) and/or the decorative film (8) is provided with a removable protective film or protective layer on the side facing the shaping surface of the blow mold before it is placed in the blow mold. Procedure according to one of Claims 12 until 16 , in which the cooling time of the hollow body (1) in the blow mold is reduced by blowing cooling air into the hollow body (1). Procedure according to one of Claims 12 until 17 , In which the cooling time of the hollow body (1) in the blow mold is reduced by cooling the blow mold. Procedure according to one of Claims 13 until 18 , in which, before the removal of the hollow body (1), a negative pressure previously applied to hold the reflector foil (3) in the blow mold is switched off or switched to positive pressure. Procedure according to one of Claims 12 until 19 , in which the removal of the hollow body (1) takes place with a handling device or with a tool. Procedure according to one of Claims 12 until 20 , in which the reflector foil (3) and/or the decorative foil (8) is inserted into the mold as a pre-stretched foil. Procedure according to one of Claims 12 until 21 , in which the blow mold has a plurality of cavities for forming a plurality of hollow bodies (1) for traffic signs (10), it being possible for the same or different reflector foils (3) to be inserted into each cavity in order to produce adhesive-free, in-mold processing, to be integrally formed on the hollow body (1).

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