Method for producing a body protection device and the body protection device produced thereby

Abstract

The invention relates to a method for producing a body protection article and the body protection article produced thereby. The method comprises: producing a structural shell (10) with a maximum thickness of 5 mm, the structural shell being made of a thermoplastic material and defining a concave interior (11) and a convex exterior (12); and overmolding a foamed polystyrene layer (20) superimposed on the concave interior (11) of the structural shell (10) so as to produce adhesion by intimate contact with the structural shell (10), wherein the structural shell (10) is produced by distributing a mixture of thermoplastic material and reinforcing fibers in a mold, the reinforcing fibers being stable at a temperature equal to or lower than the melting temperature of the thermoplastic material, sealing the mold and heating it so that the thermoplastic material melts without damaging the reinforcing fibers, and then cooling the mold so that the thermoplastic material and the reinforcing fibers embedded therein harden.

Description

Technical Field

[0001] The present invention relates to the field of methods for manufacturing body protections, and to body protections produced by said methods, the body protections comprising a structural shell and a foamed polystyrene layer. It is understood here that the shell is the outermost layer of the body protection, i.e. the layer that first receives impact.

[0002] The structural shell is a rigid member designed to provide substantial protection against impacts and to distribute stresses over a larger area than the impact surface, thereby reducing local pressures and thereby reducing direct damage that said impact may cause to the part of the user's body protected by said body protector.

[0003] Although the preferred use of the body protector is in the shape of a helmet to protect the user's head, the body protector can also be a protector for a joint, such as an ankle, knee, elbow or shoulder, a protector for the long bones of the leg or arm, a protector for the limbs such as part of a boot or glove, or it can also be a protector for the torso.

[0004] Typically, a layer of expanded polystyrene is placed within the structural shell of the helmet, which absorbs the energy of large impacts to protect the head in the helmet.

[0005] Spreading the force over a large area allows a larger portion of the expanded polystyrene layer to contribute to the impact deceleration process, thus homogenizing the mechanical response of the component against impacts on a smaller surface area. The structural shell also has other functions, such as wear resistance.

[0006] The proposed body protection device can be, for example, a car helmet for a car, motorcycle or other vehicle, a bicycle helmet, a ski helmet, a helmet for adventure activities (such as mountaineering, skydiving, paragliding), a sports helmet (such as for hockey, baseball, American football), a work helmet (such as construction, mining helmets) and other body protection devices, such as elbow guards, wrist guards, knee pads, ankle guards, shoulder guards, at least parts of boots or gloves, shin guards, arm or forearm protectors, groin protectors, chest or back protectors, etc. Background Art

[0007] The known body protection device comprises an outer shell to the inside of which is bonded a layer of expanded polystyrene for absorbing shocks.

[0008] Depending on the type of helmet and the test regulations that need to be met, there are structural shells and non-structural shells. Structural shells are used to withstand impacts and provide protection, while non-structural shells only provide protection against abrasions but not impact protection.

[0009] The thickness of non-structural shells is usually very limited, usually less than 1 mm. Usually, these non-structural shells are produced starting from a straight sheet by means of thermoforming. The structural impact resistance of this type of non-structural shell relies on the base layer of the helmet, which is made of a material suitable for absorbing impacts, usually expanded polystyrene or Styrofoam.

[0010] In the field of bicycle helmets, a non-structural outer shell is usually used, on which an expanded polystyrene layer is over-molded. Due to this over-molding process, the expanded polystyrene layer is closely contacted and connected to the non-structural outer shell.

[0011] Typically, the non-structural housing is also made of polycarbonate, which has a melting temperature much higher than the temperature reached during the overmolding process of expanded polystyrene, so the material is not altered during the overmolding process, however, expanded polystyrene has limited adhesion to polycarbonate and they tend to eventually separate over time.

[0012] The thickness of the structural shell is typically up to several millimeters. In the most common embodiments, the structural shell is made of a plastic material, typically a thermoplastic, which can be easily manufactured by injection molding, allowing for cheap and fast manufacturing, but requires considerable thickness to achieve sufficient structural strength, producing a high-weight structural shell that may be uncomfortable to wear for extended periods of time or be disadvantageous in competitive sports situations or high-performance situations.

[0013] Where a low weight structural shell is required, structural shells made from composite materials are known to provide adequate structural protection with a reduced thickness and therefore a reduced weight.

[0014] These composite structural shells are made of glass and / or carbon fibers combined with a thermosetting matrix (e.g., epoxy, polyester, or vinyl ester). Once cured, the thermosetting material cannot be heated to melt or soften; therefore, if these structural shells are used in a secondary molding process of expanded polystyrene, they will not change, although the adhesion to the thermosetting matrix is ​​not very high and separation is likely to occur.

[0015] The composite structural shell is also more expensive to manufacture than a structural shell made of plastic material without reinforcing fibers, so there is a need for a solution that can reduce its cost.

[0016] In the field of body protection devices with full-face helmets consisting of a structural shell, since these helmets have a closed shape, the expanded polystyrene is not overmolded onto the inner surface of the structural shell, since the molds required are very complex, but the expanded polystyrene layer is made separately and is subsequently brought into and adhered to the concave interior of the structural shell. This solution limits the contact between the structural shell and the expanded polystyrene layer to a few points where the adhesive is placed, so the said layer is not adhered over its entire surface and, therefore, in this type of helmet, the strength and rigidity of the structural shell are not improved when including the expanded polystyrene layer. In other words, the mechanical properties of the assembly formed by the structural shell plus the impact-absorbing material are typical of a system made of two superimposed materials without being connected to each other. Moreover, it is not possible to automate the process of inserting and bonding the two parts, which increases the final cost of the helmet.

[0017] In the case of manufacturing the expanded polystyrene layer separately and subsequently adhering it by means of an adhesive to the structural shell made of composite material, there is the aforementioned limitation that the mechanical properties of the structural shell are not improved, they will be typical of a system made of two superimposed materials without being connected to each other.

[0018] EP2808160 discloses a manufacturing method, in particular intended to manufacture a body made of a thermoplastic matrix composite material, the body having an inner cavity open to the outside, the cavity comprising at least one concave curved wall, and the size or width of the opening to the outside being smaller than the maximum dimension between two opposite walls of the inner cavity. In particular, the hollow body may be the outer shell of a protective helmet, such as a motorcycle helmet, or a structural component of a sports shoe for sports requiring very rigid footwear.

[0019] EP1627575 discloses a helmet 10 comprising an outer shell 11 forming a bubble 12 with a lower part or base 12a and a chin protector 13, an annular band or strip 20 located within and at a certain distance from the base 12a of the bubble and the chin protector 13, and a layer of expanded polystyrene 30 injected onto the inner surface of the bubble or injected into an intermediate annular gap or space 14 (Figure 4), which is delimited on the inside by the annular band 20 and on the outside by the base 12a of the bubble and the chin protector 13.

[0020] Therefore, there is a need for a solution that allows obtaining a helmet with a strong, lightweight and low-cost structural shell that can be firmly attached to the expanded polystyrene layer, thereby further increasing its strength.

[0021] This and other advantages are obtained from the products proposed below. Summary of the invention

[0022] According to a first embodiment, the invention relates to a method for manufacturing a body protection device, the method comprising the following steps in a manner known in the prior art:

[0023] Producing a structural shell having a maximum thickness of 5 mm, the structural shell being made of a thermoplastic material and defining a concave interior and a convex exterior;

[0024] A secondary molded expanded polystyrene layer is formed which coincides with the concave interior of the structural shell and creates adhesion by being in close contact with the structural shell.

[0025] It should be understood that the structural shell is the outermost layer of the body protection device, directly receiving the impact in the event of an accident. The structural shell defines a concave interior, corresponding to the interior of the helmet, for accommodating the body part of the user to be protected.

[0026] Inside the concave shape, a layer of expanded polystyrene is superimposed, which, underneath the structural shell, will always surround the user's body parts.

[0027] The expanded polystyrene layer deforms and breaks when subjected to severe impact, thereby absorbing energy that is not transferred to the user's body parts, while completing stroke deceleration to reduce the maximum acceleration borne by the head, thereby protecting the head.

[0028] In the manufacturing step of the expanded polystyrene layer on the inner surface of the structural shell, the expanded polystyrene layer and the concave inner part of the structural shell are brought into close contact to generate adhesion through secondary molding, that is, all outer surfaces of the expanded polystyrene layer are opposite to and connected to the concave inner part of the structural shell, without any gap or separation between the surfaces, and without any intervening materials such as adhesives, and the expanded polystyrene layer is included in any existing corners, reliefs or textures of the concave inner surface of the structural shell.

[0029] This intimate contact is achieved by overmolding a layer of expanded polystyrene on the inner surface of the structural shell. The manufacturing process comprises manufacturing the structural shell, introducing it into a mold, closing the mold, introducing a material constituting pre-expanded polystyrene and steam at a temperature between 100° C. and 130° C. into the closed mold, causing the expanded polystyrene to expand by an expansion agent, so that it is molded to conform to the concave inner surface of the structural shell, thereby maintaining adhesion by intimate contact without the need for an adhesive.

[0030] According to this characteristic, although there is no adhesive between the expanded polystyrene layer and the structural shell, they still remain tightly connected, which can reduce the manufacturing cost on the one hand because no assembly steps or the use of adhesives are required, thus saving labor and time.

[0031] Furthermore, the tight connection between the two components also allows them to fit together structurally, which can increase the ultimate strength of the helmet, improving its functionality, or, due to the structural reinforcement provided by the tight connection with the expanded polystyrene layer, allow the thickness of the structural shell to be reduced without losing strength, which can reduce material and weight, thereby reducing costs and improving its performance, especially for competition or high-performance use.

[0032] The present invention proposes, in a manner unknown in the prior art, that the steps of manufacturing a structural shell include: dispersing a mixture of a thermoplastic material and reinforcing fibers in a mold, wherein the reinforcing fibers are stable at a temperature equal to or lower than the melting temperature of the thermoplastic material, closing the mold and heating it to a temperature higher than the melting temperature of the thermoplastic material so that the thermoplastic material melts without damaging the reinforcing fibers, and then cooling the mold so that the thermoplastic material and the reinforcing fibers embedded therein harden to form a composite material.

[0033] Thermoplastics, or plastics that can be repeatedly melted by heating, exhibit great adhesion to expanded polystyrene, so using this type of thermoplastic can greatly improve the structural integrity of the helmet.

[0034] The reinforcing fibers increase the strength of the structural shell, which can increase the strength of the structural shell again, or can maintain the strength and reduce the thickness of the structural shell, making it lighter and cheaper.

[0035] Thus, the combination of the use of a structural shell made of a composite material comprising thermoplastics and reinforcing fibers, and the use of a layer of expanded polystyrene adhered by intimate contact to the concave interior of the structural shell, provides a helmet that performs better and is more affordable than the helmets known in the prior art, since it is possible to obtain a helmet that is as strong as other known helmets, but with a thinner and lighter structural shell, or it is possible to obtain a helmet that is stronger than other known helmets of the same weight, all with a moderate manufacturing cost.

[0036] According to another embodiment of the method, the thermoplastic material is brought into the mold in the shape of strands and / or reinforcing fiber coatings.Preferably, the thermoplastic material and the reinforcing fibers are brought into the mold included in a woven fabric or nonwoven fabric.

[0037] The woven fabric and / or nonwoven fabric can be brought into a mould to form overlapping layers. In this case, it is proposed that at least the layer constituting the outer surface of the structural shell consists only of thermoplastic strands, thereby producing a structural shell in which the density of the reinforcing fibers in the concave interior is greater than the density of the reinforcing fibers in the convex exterior.

[0038] The reinforcing fibers are preferably long fibers, or long fibers having a length greater than 30 mm.

[0039] The reinforcing fibers are preferably selected from glass fibers, carbon fibers, aramid fibers or a combination thereof.

[0040] It is also proposed that the thermoplastic material is preferably polyethylene terephthalate, low-grade melting polyethylene terephthalate, or low-grade melting polyethylene terephthalate having a melting temperature comprised between 165° and 190°.

[0041] It is also suggested that the reinforcing fibers comprise 45% to 65% of the total weight of the structural shell.

[0042] According to one embodiment of the method, after manufacturing the structural shell, and without removing the structural shell from the manufacturing mold, the part defining the concave interior of the mold is removed and replaced with a new part, thereby defining, together with the mold part of the convex exterior of the molded structural shell, a secondary molding chamber containing the structural shell, and in the secondary molding chamber, the expanded polystyrene layer is secondary molded on the concave interior of the structural shell.

[0043] This can reduce the tools required for manufacturing, reduce the number of operations required for manufacturing, and therefore speed up said manufacturing.

[0044] According to a second aspect of the invention, the invention relates to a body protection device obtained by the aforementioned method, comprising in a known manner:

[0045] a structural shell made of a thermoplastic material having a maximum thickness of 5 mm and defining a concave interior and a convex exterior;

[0046] The expanded polystyrene layer coincides and adheres to the concave interior of the structural shell over the entire surface by intimate contact.

[0047] The proposed body protection device further comprises the following features in a manner not known in the prior art:

[0048] The structural shell is made of a composite material including a thermoplastic having a predetermined melting temperature and reinforcing fibers embedded therein, the reinforcing fibers being stable at a temperature equal to or lower than the melting temperature of the thermoplastic material.

[0049] According to another embodiment of the body protection device, it is proposed that the structural shell may have a higher density of reinforcing fibers in its concave inner portion than in its convex outer portion. This may expose the reinforcing fibers on the surface of the concave inner portion, or at least affect the surface finish of the concave inner portion, creating tiny protrusions or holes, thereby improving the adhesion of the expanded polystyrene layer, while the defects are avoided in the convex outer portion of the structural shell.

[0050] This can be achieved, for example, by manufacturing the structural shell starting from two coincident layers having different reinforcing fiber densities, the layers typically being placed inside the mold before closing the mold and continuing to melt the thermoplastic material.

[0051] According to an embodiment of the present invention, the thermoplastic is polyethylene terephthalate, commonly known by the abbreviation PET.

[0052] Preferably, low-melting polyethylene terephthalate is used, for example, polyethylene terephthalate with a melting temperature between 165° and 190°, which facilitates the molding process of the housing and speeds up its manufacturing speed and reduces its cost.

[0053] Structural shells made of polyethylene terephthalate or low-grade melting polyethylene terephthalate are deformed by the heat applied during the secondary molding of the expanded polystyrene layer, which is necessary to obtain adhesion by intimate contact. However, the addition of reinforcing fibers to the thermoplastic material prevents this problem, thus enabling the use of the thermoplastic material in combination with the expanded polystyrene layer attached by intimate contact without the need for the intervening adhesive.

[0054] Preferably, the reinforcing fibers may be selected among glass fibers, carbon fibers, aramid fibers or a combination thereof. This type of fiber does not change even during the manufacturing process of the structural shell, which requires melting a thermoplastic material in which the reinforcing fibers are embedded in a mold for molding the structural shell.

[0055] Preferably, the reinforcing fibres will be long fibres, for example greater than 30 mm in length, which may provide greater reinforcement to the structural shell.

[0056] The use of long fibers prevents the thermoplastic material from being injected into the mold for manufacturing the structural shell, since the long fibers cannot flow and maintain the correct distribution inside the mold, because they become entangled with each other due to their length. Therefore, using this type of fiber, it is necessary to deposit the reinforcing fibers in the final position in the mold before closing the mold and melting the thermoplastic material to manufacture the structural shell.

[0057] Typically, the reinforcing fibers will form a woven fabric, ie a fabric having a weft and warp structure, and thus in contrast to a nonwoven fabric. Nevertheless, the use of nonwoven fabrics is also contemplated.

[0058] The fabric is deposited in a mould which is then closed and heated to obtain a structural shell.

[0059] It is also proposed that the fabric, whether woven or nonwoven, comprises, in addition to the reinforcing fibers, thermoplastic fibers or a thermoplastic coating of the reinforcing fibers, before closing the mold and heating the mold to produce the structural shell. In this way, while the reinforcing fibers are placed in the mold, the thermoplastic material is also placed, which will be melt-formed into the structural shell, so that the reinforcing fibers are embedded therein.

[0060] It is proposed that the reinforcing fibers account for 45% to 65% of the total weight of the structural shell.

[0061] Typically, the expanded polystyrene layer has a minimum thickness of 10 mm, preferably at least 15 mm.

[0062] Preferably, the proposed body protection is a helmet or a full helmet, elbow pads, wrist guards, knee pads, ankle pads, shoulder pads, at least part of a boot or a glove, a shin guard, an arm or forearm protector, a groin protector, a chest or back protector.

[0063] Further features of the present invention will appear from the following detailed description of exemplary embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The above and other advantages and features will be more fully understood from the following detailed description of exemplary embodiments taken in conjunction with reference to the accompanying drawings, which must be taken in an illustrative and non-limiting manner, in which:

[0065] Figure 1 A perspective view of a structural shell according to one embodiment is shown, wherein the helmet is a full-face helmet;

[0066] Figure 2 A helmet made of a structure (e.g. Figure 1 A cross-sectional view of a full-face helmet formed by a helmet as shown in FIG. 1 , which has a foamed polystyrene layer connected by intimate contact to the concave interior of a structural shell. DETAILED DESCRIPTION

[0067] The drawings show exemplary embodiments of the invention having an illustrative, non-limiting character.

[0068] Figure 1 1 , a structural shell 10 is shown. In this example, the structural shell 10 is a structural shell for a full-face helmet, including a lower opening for inserting the user's head therein and a front opening for the mask so that the user can see through it.

[0069] Obviously, the invention is also applicable to other types of helmets not shown, such as non-full-face helmets, or even helmets with ventilation openings, such as bicycle helmets.

[0070] The structural shell 10 defines a concave interior 11 intended to oppose and at least partially surround the head of a helmet user and a convex exterior 12 that will remain exposed and receive impact first.

[0071] The structural shell 10 is made of a composite material, ie a composite material to which thermoplastics are added and in which reinforcing fibers are embedded.

[0072] like Figure 2 As shown, the proposed helmet also comprises a layer of expanded polystyrene 20 located within the structural shell 10 .

[0073] The expanded polystyrene layer 20 is attached to the concave interior 11 of the structural shell 10 by a tight connection without intervening adhesive; that is, there is no gap, space or separation between the structural shell 10 and the expanded polystyrene layer 20. This is achieved by overmolding the expanded polystyrene layer 20 onto the structural shell 10.

[0074] In this embodiment, it is recommended that the thickness of the structural shell be between 2 mm and 4 mm.

[0075] According to a preferred embodiment, the thermoplastic material incorporated into the structural shell 10 will be polyethylene terephthalate, commonly known as PET, and the reinforcing fibers will be long glass fibers, carbon fibers or aramid fibers, or even mixtures thereof.

[0076] Polyethylene terephthalate is inexpensive, tough, durable, and easy to manufacture, and also provides excellent adhesion by being in close contact with the expanded polystyrene layer 20. The reinforcing fibers embedded in the polyethylene terephthalate increase its structural strength and protect it from thermal deformation during the secondary molding process of the expanded polystyrene layer.

[0077] In addition, it is better to use low-melting polyethylene terephthalate, which is a thermoplastic material with a melting temperature between 165° and 190° C. This low melting temperature can reduce costs and speed up its manufacturing without affecting its strength. Due to the stability provided by the reinforcing fibers, the low-melting polyethylene terephthalate will not deform when the expanded polystyrene layer 20 is applied.

Claims

1. A method for manufacturing a body protection device, comprising: producing a structural shell having a maximum thickness of 5 mm, the structural shell being made of a thermoplastic material and defining a concave interior and a convex exterior; overmolding an expanded polystyrene layer, said expanded polystyrene layer coinciding with said concave interior of said structural shell; wherein the structural shell is manufactured by dispersing a mixture of a thermoplastic material and reinforcing fibers in a mold, the reinforcing fibers being stable at a temperature equal to or lower than the melting temperature of the thermoplastic material, closing the mold and heating the mold to a temperature higher than the melting temperature of the thermoplastic material to melt the thermoplastic material without damaging the reinforcing fibers, and then cooling the mold to harden the thermoplastic material with the reinforcing fibers embedded therein to form a composite material, It is characterized in that Integrating the thermoplastic material and the reinforcing fibers into a woven fabric or a nonwoven fabric and bringing them into the mold; bringing overlapping layers of woven fabric and / or nonwoven fabric into the mold; and Prior to melting, at least the woven fabric layers and / or nonwoven fabric layers constituting the outer surface of the structural shell consist exclusively of strands of thermoplastic material, thereby producing a structural shell, wherein after melting and hardening, the density of the reinforcing fibers is higher in the concave interior of the structural shell than in the convex exterior of the structural shell, and wherein; The expanded polystyrene layer is overmolded onto the concave interior of the structural shell without any gap, separation or any intervening material between the expanded polystyrene layer and the concave interior of the structural shell, so that the expanded polystyrene layer is contained in any existing corners, reliefs or textures of the concave interior, and adhesion of the expanded polystyrene layer to the concave interior is generated by intimate contact between the expanded polystyrene layer and the concave interior of the structural shell.

2. The manufacturing method according to claim 1, wherein: The thermoplastic material is brought into the mold in the form of strands and / or the reinforcing fibers are brought into the form of a coating.

3. The manufacturing method according to claim 1, wherein: The thermoplastic material is polyethylene terephthalate.

4. The manufacturing method according to claim 1, wherein: The reinforcing fibers are selected from glass fibers, carbon fibers, aramid fibers, or a combination of the above materials.

5. The manufacturing method according to claim 1, wherein: The reinforcing fibers comprise 45% to 65% of the total weight of the structural shell.

6. The manufacturing method according to claim 1, wherein: After manufacturing the structural shell, and without removing the structural shell from the mold, the part defining the concave interior of the mold is removed and replaced with a new mold part, which, together with the mold part that has molded the convex exterior of the structural shell, forms a secondary molding chamber containing the structural shell, and in the secondary molding chamber, the expanded polystyrene layer is secondary molded within the concave interior of the structural shell.

7. A body protection device obtained by the method according to any one of the preceding claims 1 to 6, comprising: a structural shell made of a thermoplastic material and having a maximum thickness of 5 mm and defining a concave interior and a convex exterior; a layer of expanded polystyrene, said layer of expanded polystyrene coinciding with the entire surface of said concave interior of said structural shell; wherein the structural shell is made of a composite material, the composite material comprising a thermoplastic having a preset melting temperature and reinforcing fibers embedded therein, the reinforcing fibers being stable at a temperature equal to or lower than the melting temperature of the thermoplastic; It is characterized in that The reinforcing fibers form a woven or nonwoven fabric within the composite material; and The density of the reinforcing fibers is higher in the concave interior of the structural shell than in the convex exterior of the structural shell; The expanded polystyrene layer is in intimate contact with the concave interior of the structural shell, with no gaps, partitions or any intervening materials between the expanded polystyrene layer and the concave interior of the structural shell, so that the expanded polystyrene layer is contained in any existing corners, reliefs or textures of the concave interior, and the expanded polystyrene layer is adhered to the concave interior by the intimate contact between the expanded polystyrene layer and the concave interior of the structural shell.

8. The body protection device according to claim 7, wherein: The thermoplastic material is polyethylene terephthalate.

9. The body protection device according to claim 7, wherein: The reinforcing fiber is selected from glass fiber, carbon fiber, aramid fiber, or a combination of the above materials.

10. The body protection device according to claim 7, wherein: The reinforcing fibers are long fibers with a length greater than 30 mm.

11. The body protection device according to claim 7, wherein: The reinforcing fibers comprise 45% to 65% of the total weight of the structural shell.

12. The body protection device according to claim 7, wherein: The body protection device is a helmet, elbow pads, wrist guards, knee pads, ankle pads, shoulder pads, at least part of a boot or a glove, a shin guard, an arm protector, a groin protector, a chest or back protector.

13. The body protection device according to claim 7, wherein: The body protection device is a full-face helmet or a forearm protection device.

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