DE102008010755B4 - Handle for a tool - Google Patents

Abstract

The handle (1) has an outer layer (6) made of flexible plastic e.g. silicone rubber, with a non-porous structure and hardness in a range of 30 to 60 shore A, and an inner layer (5) made of flexible plastic with hardness in a range of 10 to 55 shore A. A handle core (3) is made of hard plastic. The plastic forming the inner layer in the core has a free softener content that amounts to 60-130 percentage of the content in the plastic forming the outer layer. A compound selected from a group consisting of olive oil, larch resin, castor oil, or paraffin oil, is provided as the softener.

Description

The The invention relates to a handle for a tool for transmission a torsional moment, a lateral force or impact force or a Compressive force, such as a handle for a screwdriver, a Trowel, a hammer, a chisel, a saw, a Hand or garden tool or a Handle for a sports equipment, Leisure equipment or bicycle.

STATE OF THE ART

To improve the feel and ergonomics of a handle of a screwdriver used for the handles plastics are specifically provided with plasticizers that should give the handle at least a radial elasticity, so that the handle of a user's hand can better adapt. While conventional so-called "two-component grips" are initially believed to form a core grip-forming inner layer of the handle stiff or hard and to coat this inner layer with a relatively thin soft outer layer to achieve an improvement in haptics is in applications of the applicant (cf. WO 2007/079787 A1 and WO 2007/048550 A1 another approach has been suggested: Here, the outer layer is harder than an inner layer, resulting in a durable, relatively hard surface. By specifying the radial layer thickness of the outer layer, a radial deformability of the handle can still be ensured, wherein the outer layer is relatively soft supported radially inwardly through the inner layer. In other words, for the above-mentioned conventional two-component handle, the rigidity increases radially inward, while for the aforementioned handles of the applicant, the rigidity decreases radially inward from the outer layer to the inner layer. Moreover, in the said applications, the applicant proposes to form the handle in the manner of a "three-component handle", since the handle is constructed with a hard grip core, a soft inner layer and a harder outer layer, between grip core and softer inner layer may additionally be provided a handle core sheath. In the applications of the Applicant mentioned, the design of the inner layer with a hardness of 10 to 55 Shore A and the outer layer with a hardness of 30 to 60 Shore A is preferably proposed.

The most commercially available Thermoplastic elastomers (TPEs) are compounds of various types Types of plastics. The adjustment of the desired degree of hardness is done by training of plasticizers in the compound. Such plasticizers are for. B. paraffin oil or phthalates leading to an "external" softening can be used. In such an "external" softening the plasticizer is located freely between individual molecular chains in unbound form. Such free plasticizers are prone to a migration to adjacent layers. In addition, the Content of the plasticizer in a plastic becomes greater, the lower the desired Hardness is, which further aggravates any migration.

DE 299 04 043 U1 describes a handle for impact drills, grinders and other crafting machines. On the actual cup-shaped housing part or support member, which may be made of plastic or metal, a three-layer polyurethane coating is applied, wherein between two layers with a fine cell structure, an intermediate layer with a coarse cell structure is interposed. By such a coating, the vibration damping, the sweat absorption properties and the durability or workshop suitability to be improved.

The non-generic DE 30 00 238 A1 relates to a multilayer waterproofing membrane made of soft PVC. The properties of the geomembrane are largely determined by the amount and type of plasticizer in the layers. In this case, it comes over time as a result of plasticizer loss to a hardening or embrittlement of the geomembranes, which makes them useless. The document initially proposes to provide an outer layer of the geomembrane only with a normal plasticizer content, so that it remains dry grip, due to their strength is less vulnerable and when rolling no block effect occurs. To counteract the aforementioned embrittlement of this layer, another layer is provided which has an increased plasticizer content and serves as a kind of "softener reservoir". From this plasticizer reservoir then takes place with the plasticizer loss of the other layer, a balance of the plasticizer content, so that this document specifically wants to exploit a plasticizer diffusion between the layers.

Further prior art is in particular from DE 297 05 522 U1 . US Pat. No. 6,370,986 B1 . US Pat. No. 3,770,033 and the alien DE 203 10 882 U1 known.

OBJECT OF THE INVENTION

The present invention has for its object to provide a handle for a tool for transmitting a torsional moment or a compressive force, in which the migration of the plasticizer is avoided or a tolerierba Res extent is limited.

SOLUTION

The The object underlying the invention is achieved by a handle with the Features of claim 1. Further embodiments of the handle according to the invention arise according to the features of the dependent claims 2 to 9th

DESCRIPTION OF THE INVENTION

Of the The present invention is based on the finding that in usual Grips with layers of different hardness a slope in the plasticizer content of a softer layer consists of a hardening layer. As a result this gradient Softener migrates from the softer layer to the harder layer. This migration or migration has the consequence that the Hardness in the layers of the constructive and manufacturing conditional predetermined Values are moved away, so the handle will be its predetermined over time Loses properties. About that In addition, due to migration on the surface of the Handle, so the outer surface the outer layer, form a film from the plasticizer. Such a movie is undesirable, because of this the friction between the user's hand and the lateral surface of the handle decreases. However, a high coefficient of friction is for transmission a torque, for example in the case of the use of the handle for one Screwdriver, required.

On Building on this knowledge, the invention has recognized on the one hand, that cause of the mentioned migration a slope of the free plasticizer in the individual layers. In extreme cases, this means that the problem of migration is eliminated or minimized can, if the individual layers equal free plasticizer contents have. On the other hand, investigations by the applicant have led to the Result led that the use of exactly the same amount of plasticizer to avoid Migration is not mandatory. Rather, one seems some deviation of the levels of plasticizers in the inner and outer layers possible, without causing excessive migration the plasticizer occurs or a migration occurs, which is to the described undesirable Effects. Here beats the invention before, in the for the inner layer and the outer layer used plastics do not have a greater gradient of free plasticizer content from the inner layer to the outer layer to provide, the slope is limited so that the inner layer forming plastic contains a free plasticizer content of at least 60% and at the most 130%, in particular at least 70% and at most 120%, for example at least 90% and at most 110%, of the free plasticizer content in the outer layer forming plastic. As part of the present invention is under a plasticizer content of Weight fraction of the plasticizer based on the weight of the in the Layer of plastic used, if necessary with further additives, understood without the plasticizer. Here, the "free plasticizer content" merely indicates the thus defined content of the free present in the layer Plasticizer, without losing the weight of a possibly in a molecular chain of the plastic bonded plasticizer or one contained in the plastic compound inherent softness, for example, a rubber, herein is included.

• – Entsprechend einer ersten Ausgestaltung der Erfindung kann die unterschiedliche Härte der inneren und äußeren Schicht dadurch herbeigeführt werden, dass zwar die freien Weichmachergehalte in den Schichten lediglich ein begrenztes Gefälle aufweisen. Allerdings besitzt für diese Variante die weichere innere Schicht einen zusätzlichen gebundenen Weichmachergehalt, so dass zumindest die innere Schicht in ihrem Steifigkeitsverhalten beeinflusst wird durch die kumulative Wirkung von freiem Weichmacher und gebundenem Weichmacher. Lediglich beispielhaft ist zu erwähnen, dass in der inneren Schicht zur Herbeiführung einer verringerten Härte im Vergleich zur äußeren Schicht ein gebundener Polyester-Weichmacher Einsatz finden kann. Es kann auch das für die innere Schicht verwendete Compound anders zusammengesetzt sein als das für die äußere Schicht. Das Compound der inneren Schicht kann beispielsweise auch einen von Natur aus weichen weichmacherfreien Kautschuk enthalten.
• – Entsprechend kann in beiden Schichten in die Molekülketten gebundener Weichmacher eingesetzt sein, wobei allerdings der gebundene Weichmachergehalt in der inneren Schicht höher ist als in der äußeren Schicht.
• – Für eine weitere Ausführungsform der Erfindung kann eine Beeinflussung der Härte, nämlich eine gewünschte Erhöhung der Härte der äußeren Schicht dadurch herbeigeführt werden, dass in der äußeren Schicht ein harter Füllstoff vorgesehen ist, oder der Gehalt des harten Füllstoffs in der äußeren Schicht größer ist als ein ebenfalls vorhandener Gehalt des harten Füllstoffs in der inneren Schicht oder in ihr ein Füllstoff gänzlich fehlen. Lediglich beispielhaft werden als mögliche Füllstoffe zur Erhöhung der Härte eines Kunststoffs Kreide, Glaskugeln, Glimmer, Glasfasern, Holzmehl oder ähnliche harte Verbundmaterialien erwähnt.
• – Selbstverständlich ist es ebenfalls möglich, dass eine Beeinflussung der Härten der inneren und äußeren Schicht sowohl durch den Einsatz eines gebundenen Weichmachers als auch durch die Variation des Gehalts des Füllstoffs erfolgt.

In order to achieve the desired differential hardnesses of the inner and outer layers despite the limited gradient of the free plasticizer content, the invention proposes various alternative or cumulative measures:

• - According to a first embodiment of the invention, the different hardness of the inner and outer layers can be brought about by the fact that although the free plasticizer contents in the layers have only a limited slope. However, for this variant, the softer inner layer has an additional bound plasticizer content, so that at least the inner layer is influenced in its stiffness behavior by the cumulative effect of free plasticizer and bound plasticizer. By way of example only, it should be noted that a bonded polyester plasticizer may be used in the inner layer to provide a reduced hardness compared to the outer layer. Also, the compound used for the inner layer may be composed differently than that for the outer layer. For example, the compound of the inner layer may also contain an inherently soft, plasticizer-free rubber.
• Accordingly, plasticizer bound in the molecular chains can be used in both layers, although the bound plasticizer content in the inner layer is higher than in the outer layer.
• For a further embodiment of the invention, an influence of the hardness, namely a desired increase of the hardness of the outer layer, can be brought about by providing a hard filler in the outer layer, or the content of the hard filler in the outer layer being greater than an existing content of the hard filler in the inner layer or in a filler completely missing. By way of example only, as possible fillers for increasing the hardness of a plastic, chalk, glass beads, mica, glass fibers, Wood flour or similar hard composite materials mentioned.
• - Of course, it is also possible that an influence on the hardnesses of the inner and outer layer takes place both by the use of a bound plasticizer and by the variation of the content of the filler.

For a further embodiment of the handle according to the invention, the plastic forming the inner layer has a melt flow index or melt volume flow rate MVR which is at most 30%, preferably at most 20%, of the melt flow index or the melt volume flow rate MVR of the the outer layer of plastic forming deviates. The melt flow index refers to the flowability of the plastic at defined temperatures and pressures. The melt flow index (MFI = Melt Flow Index or MFR = Melt Flow Rate) is used to characterize the flow behavior (molding composition test) of a thermoplastic under certain pressure and temperature conditions. It is a measure of the viscosity of a plastic melt. From this it is possible to deduce the degree of polymerization, ie the average number of monomer units in a molecule. The MFI is determined by means of a capillary rheometer according to DIN EN ISO 1133, wherein the material (granules or powder) is melted in a heatable cylinder and pressed under pressure through a nozzle (capillary). The mass of polymer melt (extrudate) is determined as a function of time (10 minutes). By using plastics with the mentioned melt flow indices, it is possible to achieve a desired formation of the layers in the longitudinal and radial direction within the grip body and an error-free surface on the grip. In particular, materials with MVR rates of 5 to 80, preferably 20 to 60 cm ^{3 are} used for the production of the handles, measured at a temperature of 200 ° C. and a load of the piston of the test device with 2.16 kg.

Also possible is a method of production in which the inner layer is in one first injection molding step in a first form is sprayed onto the handle core. thereto subsequently becomes the outer layer in a second form on the inner layer in a second injection molding step sprayed. The mold cavity of the second mold is so much greater than the mold cavity the first shape, as for forming the radial extent of the second layer is required (taking into account any changes with a cooling). One Such method is without the formation of a handle core sheath possible, wherein also the handle core before insertion into said first form can be provided with a handle core sheath.

Preferably finds the prevention according to the invention the migration of the plasticizer use for a handle that mentioned in the Order a handle core, a handle core sheath, the inner Layer and the outer layer has. This grip is made up of the handle core sheath and the outer layer from the same material. Handle core sheath, inner layer and outer layer are sprayed onto the handle core in a sandwich process. This may be a sandwich method in which a single mold, in which the handle core is inserted, first a first Material is injected, which at a later date, the handle core sheath as well as the outer layer forms and then afterwards, before the first material completely is cured, a second material is injected, which is the inner layer forms. Further details of such a sandwich method are the aforementioned Registration of the applicant to take. By this embodiment of the invention can the migration avoidance with those mentioned in the above Application mentioned advantages of a production in a sandwich process get connected.

advantageous Further developments of the invention will become apparent from the claims, the Description and the drawings. The in the introduction to the description advantages of features and combinations of several Features are merely exemplary and may be alternative or cumulative come into effect, without the benefits of mandatory embodiments of the invention must be achieved. Other features are the drawings - in particular the illustrated Geometries and the relative dimensions of several components to each other as well as their relative arrangement and operative connection - can be seen. The combination of features of different embodiments the invention or features of different claims is also different from the ones chosen The antecedents of the claims possible and is hereby stimulated. This also applies to such features as in separate drawings are shown or in their description to be named. These features can be combined with features of different claims. As well can in the claims listed Features for more embodiments the invention omitted.

BRIEF DESCRIPTION OF THE FIGURES

in the The invention is described below with reference to the figures preferred embodiments further explained and described.

1 shows a handle according to the invention with a handle core, a handle core sheath, an inner layer and an outer layer in egg a longitudinal section.

2 shows the handle according to 1 in a cross section II-II.

3 shows a further handle according to the invention with a handle core, an inner layer and an outer layer in a longitudinal section.

4 shows the handle according to 3 in a cross section IV-IV.

5 shows a further cross-sectional configuration of a handle according to the invention.

6 shows a further cross-sectional configuration of a handle according to the invention.

DESCRIPTION OF THE FIGURES

1 shows a handle 1 , the example finds use for a screwdriver. In the handle 1 in this case is a shaft 2 a functional part, here with a screwdriver blade, firmly received to absorb longitudinal forces or torsional moments. The shaft 2 is in this case in the opposite end of the working tip of the stem with a handle core 3 sheathed, which is to be described in first approximation as dumbbell-shaped with end-side thickening 8th . 9 , which have a hollow cylindrical connection area 10 connected to each other. The handle core 3 is formed with a hard plastic.

As in 2 can be seen, has the handle core in the connection area 10 Evenly distributed over the circumference ribs 11 here are six such ribs 11 for that in the 1 and 2 illustrated embodiment have different radial extent. The handle core 3 is of a cylindrical cylinder grip in a first approximation 4 jacketed. The outer layer 6 of the handle, which is a handle surface or jacket surface 7 of the handle 1 is formed with thin layer thickness for the illustrated embodiment approximately hexagonal. The handle core sheath 4 is via radially oriented connecting webs 12 , in the 2 in the 12 o'clock position and in the 6 o'clock position, with the outer layer 6 connected, wherein for the illustrated embodiment, grip core sheath 4 , outer layer 6 and connecting webs are formed integrally with the same material. The outer layer 6 , the connecting bridges 12 and the handle core sheath 4 limit in a first approximation as C-shaped in cross-section according to 2 to be designated chambers 13 that with an inner layer 5 are filled. For the in 2 illustrated embodiment correspond to the layer thicknesses of the handle core sheath 4 and the outer layer 6 while the layer thickness of the inner layer 5 3 to 6 times the layer thicknesses of the handle core sheath 4 and the outer layer 6 is. Of course, different layer thicknesses are possible. In the event that the outer layer 6 cooled by the contact with the mold wall faster, while in the surrounding region of the handle core, the cooling is slower, the outer layer 6 be thicker than the layer 4 ,

In 2 is still recognizable that the extended ribs 11 in the connecting bridges 12 extend, while four slightly shorter ribs, the handle core sheath 4 pass through and get slightly into the inner layer 5 extend. The shape of the handle core, the arrangement, number and extent of the radial ribs can also be designed differently than in the exemplary illustration and the description thereof.

A manufacture of a handle 1 according to 1 and 2 takes place in any sandwich process, for example a mono-sandwich process. Further references to possible manufacturing methods for such a handle and / or different embodiments of handles with an outer layer 6 and an inner layer 5 for which the inventive features can also be used are, for example, the patent applications WO 2007/079787 A1 or WO 2007/048555 A1 to be taken from the applicant.

For that in the 3 and 4 illustrated embodiment is the handle 1 without handle core sheathing 4 formed so that in a portion of the connection area 10 on the handle core radially outboard immediately the inner layer 5 followed. Furthermore, in this case the handle core 3 only with two ribs 11 formed, which are approximately halfway into the inner layer 5 extend. In the longitudinal section, in which between the outer layer 6 and the handle core 3 the inner layer is provided has the outer layer 6 an approximately constant layer thickness, while the layer thickness of the inner layer 5 from the cross-sectional area IV-IV, in which the diameter of the handle is maximum, toward the two end portions of the handle 1 can lose weight. In the cross section IV-IV, the layer thickness of the inner layer 5 1 to 2 times or 1 to 3 times the layer thickness of the outer layer.

The in 5 shown deviant construction of the handle 1 corresponds essentially to the structure of the handle according to 4 , in which case the two ribs 11 completely through the inner layer 5 extend so that faces of the ribs 11 directly to the outer layer 6 are connected.

6 shows an alternative cross-sectional configuration for which the handle is not formed with a cylindrical handle core and complementary, radially outwardly extending ribs. Rather, the grip core 3 in this case, in a first approximation rectangular, wherein the outer layer 6 adjacent end faces of the handle core 3 , here the narrow sides of the rectangular cross section, corresponding to the inner contour of the outer layer 6 can be curved.

Other embodiments for the construction of handles for tools, in particular screwdriver, which have a harder outer layer and a softer inner layer can, for example, the patent applications of the applicant, in particular DE 10 2005 037 504 B3 . WO 2006/069759 A1 . WO 2007/079787 A1 . WO 2007/048555 A1 . DE 10 2006 037 688 A1 . DE 10 2006 038 636 A1 . DE 10 2006 061 068 A1 . DE 20 2005 021 195 U1 . DE 10 2005 055 981 A1 . DE 10 2007 010 972 . DE 10 2007 038 928 and DE 10 2007 015 069 taken where possible, which can be used in the context of the invention different manufacturing methods are described.

For the production of handles of the type described can such elastic plastics used where plasticizers incorporated into the molecular chain or are networked with this, so that an "internal" plasticization is given. Such a bound plasticizer tends to migration only to a small extent. For example, the plastic with internal softening EPDM + PP-X (cross-linked) or (ethylene / propylene terpolymer / polypropylene) or polyester plasticizer. Also suitable as exposed to plastics that contain very little plasticizer, such as NR + PP-X (crosslinked) based on natural rubber or plasticizer-free TPU, thermoplastic polyurethane low hardness.

For the production The handles are made of plastic, which is made of SBS (styrene / butadiene / styrene) or SEES (styrene / ethene butene / styrene) or EPDM (ethylene / propylene / diene / rubber) or EVA (ethylene / vinyl acetate) or PP (polypropylene) or PE (polyethylene) or TPEE (thermoplastic polymers based polyester) or TPU (thermoplastic Polyurethane) or as a compound in various combinations are blended together. To adjust the plasticizers, can Softeners are added, with the respective polymer matrix compatible are.

It Also, silicone rubber with appropriate hardnesses can be used for the inner and outer layers become. Silicone rubber is free of plasticizers, so the Problem of migration does not occur.

The inner layer may have a closed structure or a porous structure. The porous structure is produced by giving the plastic a blowing agent (foaming agent) is added, which gasifies at the liquefaction temperature of the plastic and forms pores in the plastic.

The Handles are sandwiched in a first manufacturing process made in which the inner layer and the outer layer in an injection molding step by successively injecting the various plastics into the mold cavity arise. It can be used while the mono-sandwich method, at first the outer layer forming plastic from its own injection molding machine with a given Dosing fed into the injection molding is plasticized in which the inner layer forming plastic becomes. In the actual injection molding both plastics are injected without interruption through the same injection channel in the mold cavity. Also, a targeted interruption can be selected, but still the same Injection channel (or a different injection channel) can be used can. The amount of plastic forming the inner layer becomes also by the control of the injection molding specified.

at another sandwich method first becomes the outer layer forming plastic from its plasticizing unit with the specified Dosage injected directly into the mold cavity and immediately then the plastic forming the inner layer with the predetermined Dosing quantity from the other plasticizing unit. Here too the injection into the mold through the same injection channel. The Switching the mass flow of the first plastic to the mass flow the second plastic is made by a valve system which is arranged between the plasticizing units and the mold.

At the Sandwich method forms the first injected into the mold plastic a mass ball, in whose still liquid center the second one injected Plastic penetrates, causing the mass bale is spatially expanded until he rests on all sides of the wall of the mold cavity. The first injected Plastic now forms the outer layer of the injection molded part, being a thin one Layer of this material also forms around the handle core, while the second injected plastic forms the inner layer. The thin layer The handle core is also referred to as a handle core sheath.

In another production method is the inner layer is sprayed onto the handle core in a first mold in a first injection molding step. Following this, the outer layer is sprayed in a second mold onto the inner layer in a second injection molding step. In this case, the mold cavity of the second mold is so much larger than that of the first mold, as is required for the formation of the thickness and extension of the second layer. Such a method is possible without forming a handle core sheath, wherein the handle core may be provided with a handle core sheath prior to insertion into said first form. This method of production can lead to a handle structure, as this example in 3 to 6 is shown. When using such a method of preparation, a thickness of the outer layer may be 6 which is larger than in a production using a sandwich method. Such an increased thickness for a multi-stage injection molding process may follow from the fact that in this manufacturing method of the outer layer 6 a thermoplastic elastomer (TPE) must remain a relatively large gap between the inserted handle core and the sprayed inner layer and the wall of the second mold. Reason for this is u. Otherwise, the material may become too cold when the inner layer is overmolded on the mold wall, and the regions of the inner layer remote from the injection opening can no longer be enclosed because the mass flow has already come to a standstill.

1

Handle

2

shaft

3

handle core

4

Handle core-sheath

5

inner layer

6

outer layer

7

lateral surface

8th

end

9

end

10

connecting area

11

rib

12

connecting web

13

chamber

Claims (9)

Handle ( 1 ) for a tool for transmitting a torsional moment or a compressive force, a) with an outer layer ( 6 ) made of elastic plastic with non-porous structure and a first hardness in the range of 30 to 60 Shore A, b) an inner layer ( 5 ) of elastic plastic having a second hardness in the range of 10 to 55 Shore A, c) wherein the second hardness is less than the first hardness, d) and a handle core ( 3 ) made of a hard plastic, characterized in that e) in which the inner layer ( 5 ) contains a free plasticizer content of at least 60% and at most 130% of the free plasticizer content in which the outer layer ( 6 ) forming plastic is. Handle ( 1 ) according to claim 1, characterized in that the lower hardness of the inner layer ( 5 ) is achieved by using a higher bound plasticizer content in the inner layer ( 5 ) than in the outer layer ( 6 ). Handle ( 1 ) according to claim 2, characterized in that the plastic of the inner layer ( 6 ) is adjusted to a low hardness value by a bound polyester plasticizer. Handle ( 1 ) according to one of claims 1 to 3, characterized in that the lower hardness of the inner layer ( 5 ) is caused by a higher content of a hard filler in the outer layer ( 5 ) than in the inner layer ( 6 ). Handle ( 1 ) according to claims 1 to 4, characterized in that the inner layer ( 5 ) plastic has a melt flow index or a melt volume flow rate MVR which is at most 30% of the melt flow index or the melt volume flow rate MVR of the outer layer ( 6 ) deviating plastic. Handle ( 1 ) according to claim 1 to 5, characterized in that as bound or free plasticizer in the inner layer ( 5 ) and / or outer layer ( 6 ) at least one compound is selected from the group comprising diethylhexyl phthalate (DEHP), olive oil, phthalic acid esters, an alkylsulfonic acid ester of phenol (ASE), chloroparaphins, trimellitates, aliphatic diacarboxylic acid ethers, polyesters, phosphoric acid esters, fatty acid esters, hydroxycarboxylic acid esters, epoxides and solfoxides / sulfones, larch resin, Castor oil, paraffin oil, diisononyl phthalate (DINP). Acetine, Adimoll ^®, Displamoll ^®, mesamoll ^®, triacetin, Ultramoll ^® or Unimoll® ^®. Handle ( 1 ) according to claims 1 to 6, characterized in that the inner layer ( 5 ) and / or outer layer is formed with silicone rubber. Handle ( 1 ) according to claim 1 to 7, characterized in that a) the handle with a handle core, a handle core sheath, the inner layer ( 5 ) and the outer layer, wherein the handle core sheath and the outer layer are made of the same material, and b) grip core sheath, inner layer and outer re layer are sprayed onto the handle core in a sandwich process. Handle ( 1 ) according to one of claims 1 to 7, characterized in that a) the handle with a handle core, an inner layer ( 5 ) and an outer layer ( 6 ) and b) the inner layer ( 5 ) is sprayed onto the handle core or a handle core sheath in a first mold in a first injection molding step, and then, in a second mold, in a second injection molding step, the outer layer ( 6 ) on the inner layer ( 5 ), wherein the mold cavity of the second mold is so much larger than the mold cavity of the first mold, as is necessary for the formation of the thickness of the second layer.