Pen with one-piece injection-molded layered sleeve

Description

[0001] According to the preamble of the respective main claim, the invention relates to a pencil, in particular a cosmetic pencil, and a method for its production. STATE OF THE ART

[0002] Cosmetic pencils, in which the lead is held in a wooden barrel, are common. These wooden barrels are easy to sharpen and resharpen by hand using a sharpener that works on the principle of a pencil sharpener.

[0003] However, the production of wooden pencil cases is inherently quite complex. It requires shaping small wooden boards, gluing them together, and then milling them into individual pieces.

[0004] Where such pens have to be manufactured not as pencils or crayons but as cosmetic pencils, further specific problems arise.

[0005] Cosmetic pencils typically require higher-quality wood than colored pencils. This is because cosmetic pencils are generally intended to have a more even point. Cosmetic pencils also require a more or less elaborate surface finish. The individual pencils are usually varnished or coated once or multiple times. Cosmetic pencils, especially those that are more expensive than individual colored pencils, are intended to convey a special visual and tactile quality to buyers.

[0006] A typical process for producing such pencils, which is not critical with regard to the lead mass itself, involves extruding a suitable lead mass and gluing it into grooved boards or inserting it into plastic sleeves. This process is similar to the method that has proven successful in the production of colored pencils. The disadvantage of these extrusion processes is that, as a rule, only lead masses that result in relatively hard leads can be used. This is because the leads must remain manageable during further processing – leads that are too soft risk deforming when inserted into the boards that are subsequently glued together. Hard leads, however, are often undesirable, especially for cosmetic pencils, as they exhibit a so-called harder application, in that a satisfactory amount of cosmetic product can only be extracted from them under relatively high pressure.

[0007] For this reason, a different process is often used in cosmetic pencil production to produce the lead. In this process, the cosmetic compound is poured hot into prefabricated barrels with a concentric hole, where the lead cools. However, this poses the problem that cosmetic compounds can contain a relatively high proportion of volatile components (when hot). These volatile components tend to diffuse or migrate, at least over time, even when cooled.

[0008] For cosmetic pencils with such soft leads, the inner surface of the wooden barrel that holds the lead also requires special pretreatment—if a wooden barrel is to be used at all. Special measures are necessary to prevent volatile components of the lead from diffusing into the wood or even migrating within the wood, thereby removing the lead and potentially compromising the varnish on the outer surface. This problem can also occur with plastics, particularly foamed plastics. Volatile components can also diffuse into plastics and, if they have penetrated the plastic intensively enough after some time, may potentially compromise the outer surface.

[0009] To remedy this problem, German patent application DE 2 834 479 proposes building a cosmetic pencil with a grease-based lead that is coated with a metallic coating before being inserted into the barrel. A metallic coating provides a good barrier, but creates unnecessary effort. It also hinders sharpening the pencil. The metallic coating can be very thin, essentially formed by a foil. However, the long, narrow foil strips cut with the sharpener tend to tangle, because unlike cut wood shavings, there is no chip breakage.

[0010] German patent application DE 31 37 4 86 A1 addresses the same problem. It proposes enclosing the lead in a tube made of an injection-moldable plastic material, with the outside of the tube coated with a solvent-impermeable layer, such as a plastic film made of polyester. Such a construction is not only complex, but also fails to meet the high visual and haptic requirements placed on a cosmetic pencil. Furthermore, if the film is applied as a shrink tube, it can wrinkle or generally form undesirable overlaps. Furthermore, incorporating a plastic film is also problematic because the plastic film is often cut during sharpening and is not always cleanly cut off, so that the sharpened end runs the risk of quickly becoming unsightly.In addition, the problem of the lack of chip breakage, already mentioned above for the metal foil, arises. These problems are known to those skilled in the art, even though the aforementioned patent application makes no mention of sharpenability.

[0011] European patent EP 0 613 634 B1 also addresses this problem. It proposes creating a combined pencil barrel consisting of a thin-walled plastic tube that is inserted into the receiving opening of the actual pencil barrel. After these two parts have been assembled, the lead is then cast in. The inserted, thin-walled plastic tube apparently serves the purpose of sealing the lead and maintaining its shape beyond the lead's casting temperature. Due to its thin walls, it does not hinder sharpening, even when a comparatively hard plastic is used. In contrast, an easily sharpenable plastic can be used for the actual pencil barrel, which does not require consideration of the diffusion behavior of the lead components.

[0012] In general, there is a multiple conflict of objectives when manufacturing one-piece plastic pin sleeves.

[0013] First, the plastic used must be soft enough to allow sharpening using a manual pencil sharpener. Second, the plastic must retain its shape beyond the lead's casting temperature. Finally, the plastic must form the most appealing surface possible to achieve the desired visual, tactile, and high-quality appearance with as little rework as possible.

[0014] To find a viable compromise, relatively hard plastics are often used to manufacture the pen barrel. These offer the necessary durability. The ability to sharpen is usually ensured by foaming the plastics. Foamed plastics, however, cannot be processed by injection molding; instead, the barrel must be produced by extrusion. However, the foaming and extrusion processes impair the surface quality, making such barrels unmarketable without post-treatment.

[0015] An example of this is US Patent 5,360,281, which claims protection for pencil barrels made of foamed plastic. While this patent also addresses the idea of producing pencil barrels by injection molding, this idea was not incorporated into the claims—apparently because the proposed plastics exhibit poor sharpenability in their unfoamed state.

[0016] Finally, US patent application 2013 / 0121747 A1 is worth mentioning. Its goal is to provide pens with a particularly chemically and mechanically safe pen barrel. This is to be achieved by selecting a plastic blend that releases no VOCs during manufacture and use and that breaks without splintering, making the corresponding pens suitable even for small children.

[0017] In addition, the pencils should also be easy to sharpen.

[0018] To solve this problem, the US patent in question proposes that a plastic mixture consisting of ➢ at least one styrene-butadiene copolymer, ➢ and at least one styrene-butadiene-styrene block copolymer, ➢ and at least one further plastic from the group of styrene polymers, styrene-acrylonitrile polymers, acylnitrile-butadiene-styrene polymers, acryloyl-styrene-methylmethacrylates or a combination of the plastics mentioned, ➢ and at least one auxiliary substance.

[0019] This patent application does not address the problems in the manufacture of cosmetic pencils mentioned above. In particular, the application does not address the problems encountered during lead casting, nor the problem of how to achieve a high-quality outer surface. This US patent also does not provide a satisfactory solution for the problem of the migration of lead components identified by the patent. The US patent proposes counteracting the drying out of leads containing volatile components by adding waxes to the plastic mixture from which the barrel is made. However, this solution is particularly inadequate in the cosmetics sector, as there is no guarantee that the technical waxes added to the plastic will not migrate into the lead, which is undesirable since the lead is intended to release only cosmetically acceptable and harmless substances in defined quantities.

[0020] US 6,231,970 B1 describes thermoplastic starch compositions containing a particulate filler, e.g., an inorganic filler component, and an optional fiber component. The compositions comprise a thermoplastic phase comprising a thermoplastic starch melt containing at least starch blended with a suitable plasticizer under conditions such that the starch forms a thermoplastic melt. The thermoplastic phase may also contain one or more additional thermoplastic polymers and other optional reactants, liquids, or crosslinking agents to improve the water resistance, strength, and / or other mechanical properties of the thermoplastic melt, particularly upon solidification.The inorganic filler component can influence the mechanical properties, but is primarily added to reduce the cost of thermoplastic starch compositions by replacing a significant portion of the more expensive starch or starch / polymer melt. Optionally, fibers can be included to improve the mechanical properties of the thermoplastic starch compositions.

[0021] The thermoplastic starch compositions can be formed into a variety of useful articles, such as sheets, films, containers, and packaging materials. Because the thermoplastic starch compositions typically contain a biodegradable thermoplastic phase, and because the other components are either a naturally occurring mineral and optionally a natural fiber, the overall composition is typically more environmentally friendly compared to conventional thermoplastic materials. THE PROBLEM UNDERLYING THE INVENTION

[0022] In contrast, it is the object of the invention, in a first step, to provide a pen for applying a coloring and / or cosmetic substance, which has a one-piece sleeve made entirely of plastic, which can preferably be sharpened by hand using a pencil sharpener and has a high-quality, preferably glossy outer surface which requires no further finishing after injection molding, with the exception of the application of any inscription or other, usually local, decorations. THE INVENTIVE SOLUTION

[0023] The pen according to the invention has a lead made of the substance to be applied, with or without volatile components, and a sleeve enclosing the lead, which is injection-molded in one piece and in one material and is made of a thermoplastic material consisting of a mixture of a first and a second plastic phase, each of which, in its pure form, has different properties.

[0024] The term "plastic phase" in the sense of the invention is defined as follows: In the simplest, most manageable case, one of the two phases consists of only a single polymeric material (thus forming a phase in the broad sense), while the following definition applies to the other phase. In more complex cases, the following definition applies to both phases, which describes a phase in the narrower sense.

[0025] A phase in the narrower sense consists of different plastics that are all either weakly polar or all instead strongly polar, according to the polarity definition given here.

[0026] A phase is selected to consist of thermoplastics, each of which can be either conventional thermoplastics or thermoplastic elastomers. Both substance classes, thermoplastics and thermoplastic elastomers, can be present in the phase in varying proportions from 0-100%.

[0027] The crucial point is that both phases used according to the invention can be mechanically mixed macroscopically homogeneously in a compounding process or on an extruder screw after thermal melting, but they tend to partially demix again without the application of mechanical force. The diffusion limitation in the highly viscous molten polymer matrix counteracts spontaneous complete demixing. The driving force for the demixing process is a polarity difference, which mutually distinguishes all components of one phase from those of the other. One phase acts as a "structural phase," whose predominantly thermoplastic behavior is responsible for the basic stability of the cooled shaft sleeves and enables the formation of a high-quality, glossy to high-gloss, scratch-resistant surface.The second "disturbance phase", characterized by at least partially elastic behavior, allows a weakening of the structure of the structural phase in the interior of the shaft sleeve after cooling - after partial demixing - and thus guarantees an overall softer structure of the core material and better sharpenability.

[0028] "Single-material" injection molding, in the context of the invention, means that only a single material (even if it is a mixture of mixed phases) has been injected into the mold cavity, usually in a single shot, but exceptionally in several consecutive shots. This contrasts with "overmolding," in which a first material is first injected into the mold cavity and then a second material with different properties is injected onto it from a different material supply.

[0029] The pin according to the invention is characterized in that the first and second plastic phases are selected such that they partially separate during injection molding, thereby forming a sleeve which, viewed in the radial direction, has a higher concentration of the first plastic phase (in the sense of a concentration of the entire first plastic phase or, not preferably but conceptually included, at least one component thereof) in the area of its surface on the outer circumference (outer enrichment zone) than in the center, where a central depletion zone is generally present. At the same time, the first and second plastic phases are selected such that the sleeve also has a higher concentration of the first plastic phase (in the sense of a concentration of the entire first plastic phase or, not preferably but conceptually included, at least one component thereof) in the area of the surface on the inner circumference (inner enrichment zone).

[0030] The pencil according to the invention is further characterized in that it can be sharpened using a sharpener that works on the principle of a pencil sharpener, ie by turning the pencil by hand.

[0031] To determine whether a pencil can be sharpened, there are various alternative criteria that are ideally met cumulatively: ➢ A continuous chip can be removed three times in succession using the hand sharpener at the end of the pencil, the continuous cone of which corresponds to the angle at which the sharpener blade is positioned, over at least five, preferably at least eight, full pencil revolutions. This means that the chip forms a continuous curl, preferably with a thickness that remains constant over the entire length (+ / - 10% fluctuation) and ideally without an average increase in thickness of more than 15%, preferably only 10%, towards the end of the chip. ➢ The usually conical cut surface left behind by such a sharpener is preferably uniformly smooth. It preferably has no local chipping, splintering or steps (apart from the local set-off edge, which can mark the position reached by the sharpener blade when the injection process is aborted).in the form of chatter marks or in any case does not show any local chips, splinters or steps with a depth of more than 0.3 mm.

[0032] Typically, the second plastic phase is selected to ensure that the barrel can be sharpened using a sharpener similar to a pencil sharpener. This is measured by comparing it to a pencil with an identically sized barrel made entirely of the first plastic phase, which cannot be sharpened in the manner described.

[0033] In one go, you essentially get a multi-layered sleeve, which until now could only be produced using a much more complex overmolding process, in which first one sleeve part is injection-molded from the first material and then, after pulling movable slides, the second sleeve part is injection-molded from the second material.

[0034] The pin according to the invention is characterized in that the properties inherent in the pure first plastic phase are clearly evident due to their enrichment on the surface of the outer and inner circumferences, enforced by injection molding, even if a certain proportion of the second plastic phase is still present directly on the respective surface. In this way, the first plastic phase causes a layer with a high surface quality to form on the surface of the outer circumference of the pin sleeve - in one and the same primary molding process. With the correct selection of the first plastic phase, the surface can be absolutely flat and mirror-smooth as seen with the naked eye. In addition, a layer with a barrier function forms on the surface of the inner circumference of the pin sleeve. This barrier function will be explained in more detail later.It has a positive influence on mine casting and / or mine storage capacity.

[0035] The invention provides for a division of tasks. The first plastic phase is selected to achieve an excellent surface quality. If the first and second plastic phases are properly matched to achieve the necessary mixture, a surface with a mirror-like gloss, comparable to the gloss of a piano lacquer, can be achieved. With appropriate coordination, a flawless, highly homogeneous satin finish can also be achieved.

[0036] When selecting the first plastic phase, sharpenability does not need to be considered. This is because the outer enrichment zone, in which the first plastic phase is enriched on the outside, preferably to more than 80 wt.%, and even better to more than 90 wt.%, can be kept thin in the radial direction – possibly significantly thinner than with overmolding.

[0037] The same usually applies to the internal enrichment zone, in which the first plastic phase usually enriches on the inside to at least ≥70 wt.%.

[0038] Ideally, the extension R AA or R IA of the outer and / or inner enrichment zone is 0.075 mm to 0.5 mm, preferably only up to 0.35 mm, measured radially inward from the surface of the outer or inner circumference. Thus, the first plastic phase does not impede sharpening, even if it tends to be difficult to machine.

[0039] It has been found to be advantageous for the realization of the respective function if the inner enrichment zone has a slightly smaller radial extent R IA than the outer enrichment zone, whose radial extent is R AA.

[0040] Preferably, R AA > R IA and ideally even R AA > R IA *12 / 10.

[0041] With appropriately intensive cooling of the injection mold where it forms the outer enrichment zone, it is possible to ensure that the free surface of the outer enrichment zone consists of at least 95 wt.%, in some cases even 97 wt.% and more, of the first plastic phase or a plastic of the first plastic phase (and any pigments and / or fillers incorporated into it).

[0042] Within the entire outer enrichment zone, the proportion of the first plastic phase is ≥ 80 wt.%, significantly better at ≥ 90 wt.%.

[0043] With appropriately intensive cooling of the injection mold where it forms the internal enrichment zone, it is possible to achieve a proportion of the first plastic phase within the entire internal enrichment zone of at least ≥ 67 wt.%, better ≥ 70 wt.%.

[0044] Correspondingly, this is often accompanied by a central depletion zone. Within this central depletion zone, which lies in the center of the sleeve, the local wt. % content of the first plastic phase is reduced compared to the wt. % content that the first plastic phase had in the injection molding mixture prepared for injection molding. The term "center of the sleeve" refers in any case to a range of + / - 0.75 mm or at least + / - 0.5 mm around the radius area, which is calculated as the average of the radius at the surface of the outer circumference and the radius at the surface of the inner circumference. For non-circular contours, the average radius is used.

[0045] Depending on the proportion of the first plastic phase in the plastic mass injected into the mold cavity, the proportion of the first plastic phase within the entire central depletion zone is preferably at least ≤ 60 wt.%, better ≤ 55 wt.%.

[0046] On the other hand, plastics can be selected for the second plastic phase that, where they play a key role in the formation of the plastic structure, reduce the strength of the first plastic phase, even if the first plastic phase may have a higher weight percentage of the overall mixture. When selecting the second plastic phase, no consideration needs to be given to the surface quality and / or its barrier properties against lead components, since the second plastic phase does not play a key role in the formation of the surfaces.

[0047] The production of the pin's sleeve by injection molding gives the pin a specific physical quality in this case. Only injection molding, in this case, leads to the first plastic phase accumulating on the surface of the outer circumference, thereby forming the possibly piano lacquer-like or at least particularly high-quality surface – even though the first and second plastic phases were evenly mixed before injection into the injection mold. While the reasons why such demixing occurs are not yet fully understood, it is clear that the impact of the mixture of the first and second plastic phases, which is injected into the mold, on the well-cooled surface of the mold cavity initially leads to abrupt cooling. This cooling causes demixing because one plastic phase solidifies faster than the other.The different polarities of the phases act as driving forces for demixing and the different temperature conditions on the surface or inside the tool cavity cause a sequential solidification of the two phases and a macroscopic demixing due to the different cold zones in the resulting molded body.

[0048] In this way, the well-cooled surface of the mold cavity is covered with a layer consisting entirely or predominantly of the first plastic phase. The resulting layer is usually very solid, since the second plastic phase cannot exert any significant disruptive effect.

[0049] Since this layer acts as an insulator due to its poor thermal conductivity, further rapid cooling is prevented. This leads to a decrease in the separation below this layer, usually rapidly. In the center, the mixture of the first and second plastic phases remains intact even during solidification, although a change in the weight percentage is usually observed. Because the second plastic phase disrupts the microstructure, the solidified layer in this area is less solid than the layer that formed on the cooled surface of the mold cavity.

[0050] The term "sharpener" or "pencil sharpener" refers to the classic pencil sharpener used for pencils, colored pencils, and cosmetic pencils. Such a pencil sharpener has a body made of metal, wood, or plastic, a conical receptacle for the pencil tip to be sharpened, and at least one blade that removes a shaving from the tip when the pencil is turned by hand.

[0051] The term "thermoplastic" refers to a material that can be heated to a viscous state in which it can be injection molded. This term covers both traditional thermoplastics and TPEs (thermoplastic elastomers).

[0052] The first and second plastic phases are chemically different and therefore usually consist of different material classes or plastic types.

[0053] The above definition of the various terms also applies to what is said below, unless the context clearly indicates otherwise. PREFERRED FURTHER DEVELOPMENTS OF THE INVENTION

[0054] The concentration of the first plastic phase preferably decreases continuously from the outer enrichment zone and from the inner enrichment zone towards the center.

[0055] This distinguishes the pen according to the invention or its multi-layer sleeve from known sleeves, which only obtain their two- or multi-layer structure by applying a continuous additional plastic layer, a continuous film, a continuous lacquer layer or the like.

[0056] Of course, the sleeves according to the invention can also be provided with additional plastic or lacquer layers or foils, particularly for partial additional decoration, e.g. for the purpose of labeling.

[0057] Preferably, the sleeve is formed from both the first and second plastic phases across its entire cross-section, although the two plastic phases are present in locally different weight proportions, generally such that the weight proportions vary continuously along the cross-section (seen in the radial direction). In some cases, the term "entire cross-section" does not include the edge layer in the area up to 0.2 mm below the surface of the outer circumference. The same may apply to the edge layer in the area up to 0.2 mm below the surface of the inner circumference.

[0058] Ideally, the core would only have a separate layer near the surface, e.g., in the form of the peelable skin described below, and would not have a slate-like structure across the entire cross-section. This would undesirably increase the tendency for the shavings peeled off during sharpening to involuntarily crumble into tiny crumbs, thereby causing contamination, including on the cosmetic lead.

[0059] The barrier layer can be a mechanical barrier layer that is very smooth and thus prevents air pockets from forming when the lead is cast - as is often observed when leads are cast into wooden sleeves whose inner surface is relatively rough.

[0060] The barrier layer can instead or simultaneously be a chemical barrier layer, which is clearly preferred. Such a barrier layer is characterized by the fact that it limits the migration of lead components. Depending on the choice of the first plastic phase, the migration of isoparaffins and silicones and / or the migration of water and polar volatile substances, such as alcohols, is limited. The first plastic phase achieves such a limitation if it reduces migration to such an extent that no noticeable impairment (hardening / drying out) of the lead is observed, even after storage for 12 months at a constant temperature of 23°C. A barrier layer in the narrower sense is spoken of if the first plastic phase (in its pure form) is resistant to isoparaffins and silicones and / or to water and polar volatile substances, such as alcohols.Alcohols, has a lower diffusion coefficient than the second plastic phase in its pure form. Furthermore, the first plastic phase does not swell in the volatile or liquid components that can migrate out of the mine.

[0061] It has proven particularly advantageous to use a pure substance or mixture of weakly polar plastics with an electronegativity difference ΔEN in the range between 0.3 and 0.5 inclusive as the first polymer phase, but with a monomeric component or block that enables weak interactions with another, strongly polar plastic, thus preventing immediate spontaneous demixing. The electronegativity difference ΔEN is defined here and below as the maximum electronegativity difference between neighboring atoms in the polymer structure.

[0062] It is particularly advantageous to use one or more plastics from the class of styrene-acrylonitrile or acrylonitrile-styrene copolymers (abbreviated to SAN, nomenclature used here and everywhere according to DIN EN IDSO 18064). SAN is weakly polar, but can also interact with other highly polar plastics due to the acrylonitrile content it contains.

[0063] A preferred SAN composition consists of 65% to 80% by weight styrene and 20% to 35% by weight acrylonitrile, each with varying molar masses. A particularly favorable composition consists of 70% by weight styrene and 30% by weight acrylonitrile (with a tolerance of + / - 1.5% in each case). Ideally, the styrene-acrylonitrile marketed under the trademark "LURAN 378P™" by BASF SE, Ludwigshafen, Germany, is used.

[0064] The styrene-acrylonitriles, and especially LURAN 378P™, are characterized by their chemical resistance, both in pure form and in blends with other suitable plastics, particularly against amines, which are frequently used as neutralizing agents in cosmetic compositions. The styrene-acrylonitriles, and especially LURAN 378P™, are also characterized by their heat resistance. These properties are utilized here in conjunction with the inventive demixing during injection molding to impart superior properties to the surface on the inner circumference of the sleeve.

[0065] At the same time, the styrene-acrylonitriles and in particular LURAN 378P ™< are characterized by their excellent surface appearance, which is used here in conjunction with the demixing according to the invention during injection molding to give the surface on the outer circumference of the sleeve the necessary surface quality.

[0066] Styrene-acrylonitrile, and especially LURAN 378P™, are known to exhibit inherently high strength, particularly high scratch resistance, and are brittle. Therefore, cores made of pure styrene-acrylonitrile cannot be easily sharpened using a pencil sharpener with normal force.

[0067] Alternatively, a plastic from the acrylonitrile-ethylene-propylene-styrene (AES) class can be used as the first plastic phase. Ideally, the acrylonitrile-ethylene-propylene-styrene marketed by ROMIRA Gesellschaft für Vertrieb & Verarbeitung von Chemieprodukten mbH, Pinneberg, Germany, under the brand name "ROTEC A702™<" is used.

[0068] However, ABS or blends of SAN, ABS, and pure polystyrene are also possible alternatives, as are styrene-olefin copolymers. Small amounts of non-polar to weakly polar TPEs, such as TPE-S or TPE-O, can be added here. SBS as a TPE can generally lead to a reduction in surface gloss, but also helps to modulate the brittleness of the outer skin of the molded body that separates from this first structural phase. In the opposite case of a highly polar structural phase, the first plastic phase can also consist of at least one or a mixture of polar plastics with an electronegativity difference ΔEN greater than 0.5 - 1.7, e.g., from the family of polyesters, polycarbonates, polymethyl methacrylates, polyacrylates, polyurethanes, or polyamides. PET and derivatives, PCT, PBT, as well as polycarbonates and their blends are preferred here.Here, too, small amounts of polar TPEs (such as TPA, TPC or TPU) can be added if necessary to reduce brittleness.

[0069] The solidification temperature of the mixture of the first plastic phase must always be selected so that it is below that of the second phase so that demixing can take place in an appropriate manner and the high-quality, preferably piano lacquer-like surface structure can develop.

[0070] According to the invention, the second plastic phase is selected such that it weakens the strength of the first plastic phase where the sleeve does not need to be characterized by the special properties of the first plastic phase.

[0071] In general, the second plastic phase should preferably be at least one plastic or a mixture of plastics that physically crosslinks during injection molding through demixing phenomena from the first plastic phase and within itself, forming semi-crystalline regions as in polyethylene and / or through microphase separation as is common for thermoplastic elastomers. This results in a certain softness and / or elasticity in the material. The demixing due to the different polarity leads to a general weakening of the structural component, making it easier to sharpen.

[0072] In the mixture with a non-polar to weakly polar first plastic phase, the second plastic phase is at least one polar thermoplastic with an electronegativity difference ΔEN in the range > 0.5 to 1.7. It has proven particularly advantageous in this combination to use a plastic mixture of at least one representative of the class of polar thermoplastic elastomers (abbreviated to TPE-ET), preferably in pure form, as the second plastic phase. However, mixtures of TPE-ET with other polar thermoplastic elastomers, in particular thermoplastic polyamides or polyurethanes, as well as admixtures of polar thermoplastics such as PET, PCT, PBT and derivatives, polycarbonates, PMMA derivatives, polyacrylates, polyurethanes, and polyamides are also possible.

[0073] In particular, TPE-ET and their blends are used that utilize a polyether group as a soft segment. The use of the subclass of polar thermoplastic polyester elastomers or polar thermoplastic copolyesters (abbreviated to TPC-ET) belonging to this class has proven particularly advantageous. Typically, this plastic consists of a block copolymer with alternating hard and soft sections. The chemical interactions are essentially ester and / or ether-based hydrogen bonds. Ideally, the polymer sold under the trademark Arnitel EM400™< " from the company DSM Engineering Plastics BV, Polar thermoplastic copolyesters manufactured by Urmonderbaan 22, 6167 RD Geleen, The Netherlands are used.

[0074] What is astonishing is that the mixture of the first and second plastic phases described above, where it does not largely separate (in the sense that the concentration of the first plastic phase does not fall below 90% by weight), has a lower strength than would be expected based on the individual components. This results in good sharpenability. The only limited resistance of the second plastic phase to, in particular, polar, volatile or migratory liquid components of soft lead masses plays no role here, since the first plastic phase forms a barrier layer on the surface that comes into direct contact with the lead mass, as described. Furthermore, the fact that a reflective surface cannot be achieved with a TPE or TPC-ET is also irrelevant.

[0075] If the first plastic phase is a polar phase, the second plastic phase in the mixture must consist of at least one non-polar to weakly polar component. In this case, the use of thermoplastic elastomers of the SBS or EPDM type and their blends is particularly suitable. Blends, preferably with polyethylene, polypropylene, and copolymers of ethylene, propylene, butylene, styrene, and / or acyl nitrile, can also be used. Injection-moldable silicones can also be used in this case, either in pure form or in blends.

[0076] In principle, a system seems conceivable in which the first plastic phase has a weight fraction of 20 wt.% to 80 wt.%, the second plastic phase has a weight fraction of 80 wt.% to 20 wt.%, and the fillers, auxiliaries, and pigments have a weight fraction of 0 wt.% to 30 wt.%, preferably only up to 15 wt. Impurities of any kind are undesirable and are preferably avoided above the per mille range, particularly above 15 per mille. If this is not possible in individual cases, impurities of up to 5 wt.%, preferably up to 2.5 wt.%, may be tolerable.

[0077] A system configuration in which the first plastic phase has a weight fraction of at least 45%, preferably at least 55%, has proven particularly favorable for achieving the inventive effect. The recommended upper limit for the first plastic phase is usually 75%, preferably 65%. Fillers, auxiliaries, and pigments with a weight fraction of up to 15%, preferably only up to 5%, can be added.

[0078] The first and second plastic phases constitute at least the majority of the plastics used for the sleeve. This means that the sleeve according to the invention consists of the first and second plastic phases, which constitute the majority of the plastic mass, or in some cases, at least 90% by weight of the plastic mass used. The best case is that the first and second plastic phases, as well as the pigments and auxiliaries added to them, or just the two plastic phases together with the pigments added to them, constitute the entire plastic mass used for the sleeve, excluding impurities.

[0079] Otherwise, as mentioned, fillers that influence the plastic matrix but are not involved in its structure, as well as additives such as pigments, may be added. Gas or foaming agents in quantities that impair injection molding should be avoided, preferably completely.

[0080] Auxiliaries also include plastic components that are simply poured into the matrix of the first and second plastic phases and are not melted during injection molding, such as a cross-linked elastomer or a thermoset added in ground form as a filler. However, such fillers, which themselves consist of plastic, are preferably avoided, as they can increase viscosity and hinder demixing.

[0081] Preferably, the first plastic phase is selected so that the sleeve has an arithmetically averaged gloss level (GU) of more than 30 GU, preferably more than 40 GU, on the outer peripheral surface. The measurement is carried out according to ISO 2813 over a distance of 10 mm with 10 evenly spaced measuring points along the longitudinal axis L at a measuring angle of 60°.

[0082] Further effects, advantages and possible embodiments of the invention can be found in the exemplary embodiments described below. LIST OF FIGURES

[0083] The Figure 1 shows the sleeve of a pin according to the invention in a central longitudinal section. Figure 2 shows the complete pin according to the invention in a central longitudinal section. Figure 3 is an enlarged detail showing part of the fracture surface of a sleeve torn apart along its longitudinal axis. Figure 4shows a section perpendicular to the central longitudinal axis through the sleeve of a pin according to the invention. Figure 5a shows the skin peel test at a glance, at the beginning, after incision. Figure 5b shows the skin peel test in detail as it progresses. Figure 5c shows the real skin peel test in Example 3 in detail, as a photograph. Fig. 5c' shows the same as the Fig. 5c , but in graphic representation. The Figure 5d shows the actual skin peel test in Example 4 in detail, as a photograph. Fig. 5d' shows the same as the Fig. 5d , but in graphic representation. The Figure 5e shows the actual skin peel test on example 5 in detail, as a photograph. Fig. 5e' shows the same as the Fig. 5e , but in graphic representation. The Figure 6 shows the respective RAMAN spectrum for SAN and TPC-ET. Figure 7shows the RAMAN spectra for SAN and TPC-ET for the pure substances and at two different measuring points 100 and 200 at the cut surface of the sleeve. A Figure 8 is not provided. Figure 9 shows the RAMAN intensity of the spectra recorded for samples containing 0 wt% SAN, 30 wt% SAN, 50 wt% SAN, 70 wt% SAN and 100 wt% SAN and the complementary portion of TPE-ET. Figure 10 illustrates the steps in which the cut surface of the sleeve, which was manufactured according to the first embodiment, was measured using RAMAN spectroscopy. Figure 11 shows how the concentration of SAN and TPC-ET changes in the radial direction across the cross-section of the sleeve. EXAMPLES First rehearsal

[0084] The first sample demonstrates the basic principle. For a first example, which is not inventive and not previously known due to the definition given at the beginning, 60 wt. % SAN (LURAN 378P™< ) and 40 wt. % TPC-ET (Arnitel EM400™< ) are heated to a temperature of preferably 250°C + / - 10°C, bringing them to an injection-moldable, viscous state and mixing them evenly with 3% pigments (preferably black pigments of the commercially available type Carbon Black CI 77266, which is available from various companies). No other fillers or additives are added. An extruder from Leistritz, 90459 Nuremberg, Germany, can be used for this purpose.

[0085] The actual injection molding process can be carried out on an E-motion 940 / 160T injection molding machine from Engel, 90451 Nuremberg, Germany. The prepared compound is injected into the mold cavity at an injection pressure of approximately 1400 bar. The mold is cooled by a liquid medium that flows through the mold, sealed against the cavity. In particular, the core pin of the injection mold, which forms the cavity in the sleeve intended to later accommodate the lead, is itself directly cooled by the liquid medium. This means that the core pin itself is flowing through the cooling medium.

[0086] The mold is then removed, preferably by pulling the core pin together with the sleeve out of the mold cavity and then pushing the sleeve off the core pin.

[0087] The sleeve 2 produced in this way particularly preferably looks like the Fig. 1 illustrated, whereby the structural details of the sleeve 2 will be discussed in more detail later.

[0088] The resulting sleeve features a highly scratch-resistant outer surface with a piano lacquer-like gloss. It is highly resistant to the migration of lead components and is easily decorated.

[0089] In order to obtain a cross-section that is accessible for visual examination, the sleeve 2 was cut according to Fig. 1 clamped in a tearing machine and torn apart in half by correspondingly large tensile forces in the direction of its longitudinal axis L. An enlarged section of the fracture surface of cross-section 3, which is accessible for an initial optical examination supported by a microscope, shows the Fig. 3 .

[0090] Based on the Fig. 3It can be seen that a different type of layer has formed on and directly beneath the surface of the inner circumference 5 and the outer circumference 4. This finding was verified by measurements using RAMAN spectroscopy, as explained in more detail below. This results in what can be seen from the Figure 4 is shown.

[0091] As can be seen, an outer enrichment zone 6 and an inner enrichment zone 7 can be identified. The characteristics of the outer enrichment zone 6 and the inner enrichment zone 7 can be influenced by the temperature of the surface within the mold cavity. The colder the corresponding surface of the mold cavity is at the beginning of injection, the more pronounced the segregation becomes. This also applies to the inner enrichment zone 7. As already mentioned above, the temperature of the core pin representing the inner enrichment zone can be controlled by varying the coolant flow through the core pin itself.

[0092] In the present case, no portion of the second plastic phase can be detected on the free surface of the outer enrichment zone using RAMAN spectroscopy within the limits of measurement accuracy. This is not only desired in this exemplary embodiment, but generally preferred. Such a configuration is favorable for achieving the desired glossy surface, similar to a piano lacquer finish. In a radially inward direction below the free surface, the portion of the first plastic phase begins to decrease. However, down to a depth of approximately 0.2 mm, the first plastic phase accounts for more than 90 wt.%.

[0093] It is interesting to note that, at least in the area of the outer enrichment zone, there appears to be a defined boundary layer beyond which the strength of the plastic phase forming the wall of the sleeve decreases significantly. If a sleeve produced according to this first comparative example is cut diagonally with a blade, so that a diagonally projecting chip is created, as shown in the Fig. 5 As illustrated, you can peel a skin off the surface of the case with your bare hand by pulling on the chip, regardless of the depth of the cut. The skin is relatively tough and in most cases only tears off after a pull of 4 cm or more.

[0094] In general, with effect beyond this exemplary embodiment, it can be said that such skin removal tests have shown that particularly good sharpenability is always achieved when such skins can be removed with a thickness of 0.08 mm to 0.25 mm.

[0095] As far as can be explained so far, it seems that the sharpener blade is then not dependent on having to cut through the relatively tough skin completely, but rather there seems to be a mixture of cutting and tearing, which makes the process easier. Second rehearsal

[0096] To produce the second example, which is not inventive and not previously known due to the definition given at the beginning, 60 wt.% AES (ROTEC A702™< ) and 40 wt.% TPC-ET (Arnitel EM400™< ) are heated to a temperature of preferably 250°C + / - 10°C, bringing them to an injection-moldable, viscous state with the addition of 3% pigments (preferably black pigments of the above-mentioned type), and mixed evenly. No other fillers or auxiliaries are added.

[0097] The processing of this mass takes place, as described above for the first embodiment, with the aid of the machines described there, also by injection molding.

[0098] The sleeve 2 produced in this way particularly preferably looks like the Fig. 1 illustrated.

[0099] The resulting sleeve features a highly scratch-resistant outer surface with a satin gloss. It is resistant to the migration of lead components and is easily decorated.

[0100] The investigations using RAMAN spectroscopy, as explained in more detail below, show that during injection molding of this plastic mixture, a clearly recognizable outer enrichment zone and an equally clearly recognizable inner enrichment zone are formed, the extent of which varies within the ranges described above depending on the intensity of the cooling of the injection mold. Third rehearsal

[0101] To produce the third example, which is also an embodiment of the invention, 60 wt. % of a mixture of 70 wt. % AES (ROTEC A702 ™< ) and 30 wt. % polystyrene (STYROLOTION PS 416N ™< from INEOS Styrolution, Frankfurt, Germany) for the first plastic phase and 40 wt. % of a mixture of 90 wt. % TPC-ET (Arnitel EM400 ™< ) and 10 wt. % TPE-A (Pebax ®< 2533 SA 01 from ARKEMA, Colombes, France) for the second plastic phase are brought to an injection-moldable, viscous state at a temperature of preferably 250° C + / - 10° C and mixed evenly. No further fillers or auxiliary materials are added.

[0102] The processing of this mass takes place, as described above for the first embodiment, with the aid of the machines described there, also by injection molding.

[0103] The sleeve produced in this way shows a basic structure, as it Fig. 1 or the Fig. 4 illustrated.

[0104] The resulting sleeve features a highly scratch-resistant, high-quality outer peripheral surface. It is resistant to the migration of lead components and is easily decorated.

[0105] This embodiment is characterized by a boundary layer in the area of the outer enrichment zone, beyond which the strength of the plastic phase forming the wall of the sleeve decreases significantly. If a sleeve produced according to this embodiment is cut diagonally with a blade, so that a diagonally projecting chip is created, as shown in the Fig. 5As illustrated, one can peel a skin off the surface of the case with bare hands by pulling on the chip, regardless of the cut depth. The skin is relatively tough and in most cases only tears off after a pull of 4 cm or more. It is interesting to note that even such a pull test on a deeper cut, which extends into a region radially beneath the skin, leads to the thickness of the chip being peeled off decreasing on its own until, with further pulling, only the skin is peeled off. Fig. 5c shows a photo of the pull-off test for this example. Here, it's clearly visible how a deeper incision was first made, which initially produced a thick chip, but which itself gradually reduced in thickness over a short distance until (as indicated by the further path with straight edges along the circumference) only the skin could be removed, which can be seen in the upper right corner of the image.

[0106] The Fig. 5c' shows the same as the Fig. 5c , but in a graphic representation rather than a photograph, and therefore more easily reproducible. The hatching, which runs approximately in the direction of the longitudinal axis L, illustrates the deeper incision and the adjacent transition area, which extends into the region radially beneath the skin. The area with only oblique hatching running at approximately 45° to the longitudinal axis is the area directly beneath the aforementioned skin, which is exposed by removing only the skin.

[0107] Last but not least, investigations using RAMAN spectroscopy, as explained in more detail below, can be advantageous in showing that even during injection molding of this plastic mixture, a clearly recognizable outer enrichment zone and an equally clearly recognizable inner enrichment zone are formed, the extent of which varies within the ranges described above depending on the intensity of the cooling of the injection mold. Fourth rehearsal

[0108] To produce the fourth sample, which is a further exemplary embodiment of the invention, 70 wt. % of a mixture of 70 wt. % SAN (LURAN 378P (INEOS Styrolution, Frankfurt, Germany)) and 30 wt. % ABS (POLYLAC PA-727 (CHI MEI CORPORATION, Tainan, Taiwan)) for the first plastic phase and 30 wt. % of a mixture of 70 wt. % TPC-ET (Arnitel EM400 ™< ) and 30 wt. % TPE-A Pebax ®< 2533 SA 01 (ARKEMA, Colombes, France) for the second plastic phase are brought to a temperature of preferably 250° C + / - 10° C in the injection-moldable, viscous state and mixed evenly. No further fillers or auxiliaries are added.

[0109] The processing of this mass is carried out, as described above for the first sample, using the machines described there, also by injection molding.

[0110] The sleeve produced in this way shows a basic structure, as it Fig. 1 or the Fig. 4 illustrated.

[0111] The resulting sleeve features a highly scratch-resistant, high-quality outer peripheral surface. It is resistant to the migration of lead components and is easily decorated.

[0112] This embodiment is also characterized by a boundary layer in the area of the outer enrichment zone, beyond which the strength of the plastic phase forming the wall of the sleeve decreases significantly. If a sleeve produced according to this embodiment is cut diagonally with a blade, so that a diagonally projecting chip is created, as is the case with the Fig. 5As illustrated, one can peel off a skin from the surface of the case with bare hands by pulling on the chip, regardless of the depth of the cut. The skin is relatively tough and in most cases only tears off after a peeling length of 4 cm or more. It is interesting to note that even such a peeling test on a deeper cut, which extends into a region radially beneath the skin, results in the thickness of the chip to be peeled off decreasing on its own until further peeling only removes the skin. The panoramic image shown here is composed of two individual images. Fig. 5d shows a photo of the trigger test for this example. The above statements apply accordingly. Fig. 5d' shows the same as the Fig. 5d, but in a graphic representation rather than a photograph, and therefore more easily reproducible. The hatching, which runs approximately in the direction of the longitudinal axis L, illustrates the deeper incision and the adjacent transition area, which extends into the region radially beneath the skin. The area with only oblique hatching running at approximately 45° to the longitudinal axis is the area directly beneath the aforementioned skin, which is exposed by removing only the skin.

[0113] Last but not least, investigations using RAMAN spectroscopy, as explained in more detail below, can be advantageous in order to show that, even during injection molding of this plastic mixture, a clearly recognizable outer enrichment zone and an equally clearly recognizable inner enrichment zone are formed, the extent of which varies within the ranges described above depending on the intensity of the cooling of the injection mold. Fifth rehearsal

[0114] To produce the fifth sample, 70 wt.% of a mixture of 80 wt.% SAN (LURAN 378P (INEOS Styrolution, Frankfurt, Germany)) and 20 wt.% AES (ROTEC A702 ™< ) for the first plastic phase and 30 wt.% of a mixture of 90 wt.% TPC-ET (Arnitel EM400 ™< ) and 10 wt.% TPE-A (Pebax ®< 2533 SA 01) for the second plastic phase are brought to an injection-moldable, viscous state at a temperature of preferably 250°C + / - 10°C and mixed evenly. No other fillers or auxiliary materials are added.

[0115] The processing of this mass is carried out, as described above for the first sample, using the machines described there, also by injection molding.

[0116] The sleeve produced in this way looks in principle like the Fig. 1 or the Fig. 4 illustrated.

[0117] The resulting sleeve features a highly scratch-resistant, high-quality outer peripheral surface. It is resistant to the migration of lead components and is easily decorated.

[0118] This embodiment is also characterized by a boundary layer in the area of the outer enrichment zone, beyond which the strength of the plastic phase forming the wall of the sleeve decreases significantly. If a sleeve produced according to this embodiment is cut diagonally with a blade, so that a diagonally projecting chip is created, as is the case with the Fig. 5As illustrated, one can peel off a skin from the surface of the case with bare hands by pulling on the chip, regardless of the depth of the cut. The skin is relatively tough and in most cases only tears off after a peeling length of 4 cm or more. It is interesting to note that even such a peeling test on a deeper cut, which extends into a region radially beneath the skin, results in the thickness of the chip to be peeled off decreasing on its own until further peeling only removes the skin. The panoramic image shown here is composed of two individual images. Fig. 5e shows a photo of the trigger test for this example. The above statement applies accordingly.

[0119] The Fig. 5e' shows the same as the Fig. 5e, but in a graphic representation rather than a photograph, and therefore more easily reproducible. The hatching, which runs approximately in the direction of the longitudinal axis L, illustrates the deeper incision and the adjacent transition area, which extends into the region radially beneath the skin. The area with only oblique hatching running at approximately 45° to the longitudinal axis is the area directly beneath the aforementioned skin, which is exposed by removing only the skin.

[0120] Last but not least, investigations using RAMAN spectroscopy, as explained in more detail below, can be advantageous in order to show that, even during injection molding of this plastic mixture, a clearly recognizable outer enrichment zone and an equally clearly recognizable inner enrichment zone are formed, the extent of which varies within the ranges described above depending on the intensity of the cooling of the injection mold. Comparison example

[0121] For the comparative example, 60 wt.% SAN (LURAN 378P ™< ) and 40 wt.% of a generally non-polar SBS block copolymer (ALLRUNA W55 ™< ) are heated to a temperature of preferably 250°C + / - 10°C, preferably at a temperature of 250°C + / - 10°C, to an injection-moldable, viscous state and mixed evenly. No other fillers or additives are added. ALLRUNA W55 ™< is a trademark of ALLOD Werkstoff GmbH & Co. KG, 91593 Burgbernheim, Germany.

[0122] The processing of this mass takes place, as described above for the first embodiment, with the aid of the machines described there, also by injection molding.

[0123] The sleeve 2 produced in this way particularly preferably looks like the Fig. 1 illustrated.

[0124] The resulting sleeve exhibits a matte outer surface and neither a significant outer nor an inner enrichment zone. Instead, the materials remain essentially homogeneously mixed until solidification. The skin peel test cannot be performed either, as the sleeve appears to have a homogeneous strength. RAMAN spectroscopy for concentration determination

[0125] For the determination of the concentrations found in particular in the outer and inner enrichment zone according to the invention, RAMAN spectroscopy is one of the methods of choice, as is explained in more detail here using the first sample described above as an example.

[0126] The fracture surface described above proved to be ill-suited for RAMAN spectroscopy. Instead, the investigations were conducted on a cross-section created by first cutting or sawing the sleeve perpendicular to its longitudinal axis and then grinding the resulting cross-section.

[0127] To clarify the local proportions of SAN and TPC-ET, the RAMAN spectra were measured across the cross-section of the sleeve manufactured according to the first exemplary embodiment. The measurements were performed using a RAMAN spectrometer from the Almega series from Thermo Fisher Scientific, 168 Third Avenue, Waltham, MA, USA 02451.

[0128] To calibrate the device and assign the individual parts of the respective spectrum, the raw materials were first measured. This meant that plates consisting of 100 wt.% SAN and 100 wt.% TPC-ET were manufactured. As long as a measurement point lies entirely on the respective plate and the plate thickness exceeds 2 / 10 mm, the dimensions of the test specimens are irrelevant. Both plates were measured individually.

[0129] The spectra thus obtained were plotted in the diagram according to Figure 6 The dashed line shows the spectrum recorded for SAN, the solid line shows the spectrum recorded for TPE-ET.

[0130] For the SAN determination, the area of the peak which reaches its maximum at 3050 cm -1< was used. The area of the peak which is also characteristic for the SAN and whose maximum is at 2250 cm -1 could also be used. It provides comparable values and therefore does not have to be considered separately in the following, but can be ignored.

[0131] Then, one after the other, Fig. 4 The two spectra recorded were superimposed, as shown in the Fig. 7 and (as an enlarged detail) Fig. 8. It can already be seen that different concentrations of SAN and TPC-ET are present at points 100 and 200.

[0132] Then, in addition to the previously mentioned samples with 0 wt% and 100 wt% SAN, different mixtures of SAN and TPC-ET were systematically prepared and processed into the aforementioned plates without surface layer formation by suitable temperature control. These mixtures contained 30 wt%, 50 wt%, and 70 wt% SAN, as well as the complementary portion of TPC-ET. The RAMAN intensities of the spectra recorded for the individual representatives of this sample series are plotted in the diagram. Fig. 9 shows. At the Fig. 9 It can be seen that each mixing ratio has a characteristic RAMAN intensity and that there is a linear relationship between the wt% content of SAN or TPC-ET and the RAMAN intensity to be measured for each of them.

[0133] Then, as already described, the ground cross-section of the sleeve 2 produced according to the first embodiment was measured step by step, as the Fig. 10 illustrated. Measurements were taken from the outside, progressing in a radial direction, point by point to the center of the sleeve cross-section, and from the inside, progressing in a radial direction, point by point to the center of the sleeve cross-section.

[0134] These measurements result in the diagram that shows the Fig. 10 The plastic compound used for injection molding had a mixing ratio of 2 / 3 SAN to 1 / 3 TPC-ET. Based on this, and taking into account the scatter of the measurement results, it can be seen that partial demixing occurred in the injection mold during the injection molding process.

[0135] The concentration of SAN on the surface of the outer peripheral surface of the sleeve is approximately 100 wt.%.

[0136] On the surface of the inner circumferential surface, the concentration of SAN is only approximately 70 wt.%.

[0137] The same procedure is used to determine the plastic phases and their proportions in the other samples described above. The structural design of the pin according to the invention

[0138] The pin 1 according to the invention is designed in such a way that Figures 2 , 3 and 4 It usually has an outer diameter of approximately 6 to 16 mm.

[0139] At its center, it has a receptacle for the lead 8, which advantageously forms a positive-locking anti-twist device. Its cross-section can be circular, but is preferably oval, polygonal, or octagonal in order to ensure a better hold between the lead 8 and the sleeve 2. The distance between two opposite flat sides of the octagon is preferably between 3 and 5 mm. The wall thickness of the sleeve 2 is preferably in the range of 1.5 to 3 mm. The length of the pin 1, i.e. its extension in the direction of its longitudinal axis L, is generally greater than 85 mm, mostly greater than 100 mm, and up to 180 mm.

[0140] The receptacle for the lead 8 preferably extends through the entire sleeve 2 in the direction of its longitudinal axis L, i.e. the sleeve 2 forms a tube as a semi-finished product. This simplifies lead casting. This is because the sleeve can be inserted into a tightly sealing mold on the side on which it forms the cone, which will be described in more detail below, for the purpose of lead casting. This mold then gives the end of the lead in the area of the cone an attractive, usually also conical, shape. The lead mass is then poured in from the other end of the sleeve, where the seat is located, and fills the lead receptacle in the sleeve 2 and the mold cavity which forms the tip of the lead 8. A sleeve made of plastic, such as the one according to the invention, can be inserted particularly well into a tightly sealing mold for the purpose of lead casting.Because the plastic of the sleeve is reversibly elastic compared to a wooden sleeve, it can be inserted or injected into a suitable shape to create a seal. The very smooth outer surface of the sleeve contributes to achieving a secure seal.

[0141] One end of the pencil 1 tapers to a cone 12, preferably with a cone angle Pi between 20° and 60°. This end thus contributes to replicating the sharpened side familiar from a standard wooden pencil, thus forming a starting surface that is correctly positioned opposite the sharpener blade during the first sharpening, allowing the sharpener blade to remove a chip along its entire length.

[0142] The other end of the pencil 1 preferably has a seat 9 in the form of a recessed area on its outer diameter. An end cap 10 can be placed onto this seat, preferably with a locking mechanism between the seat 9 and the end cap 10. To preserve the lead as well as possible and prevent migration, an additional seal is usually provided under the cap, often in the form of a plug or silicone plug 11. The finished pencil 1 is usually kept fresh on the side where the lead 8 protrudes beyond the sleeve 2 by means of a cap 12. The very smooth and scratch-resistant outer surface achieved according to the invention facilitates the good and secure attachment of the cap 10.The surface achieved according to the invention is so scratch-resistant that even after removing and reattaching the cap 10 30 times, no dulling of the surface over which the cap 10 passes is visible to the naked eye, due to micro-scratches running along the longitudinal axis of the pin, etc. The cap 10 is designed with a slightly smaller inner diameter than the outer diameter of the sleeve 2. The cap 10 produced in this way can be attached to the surface of the sleeve 2 achieved according to the invention with suction and can also be removed from there again due to its smooth texture (no stick / slip). Concluding remarks of a general nature

[0143] Independent protection, possibly also enriched with further features from the above description and / or the already existing claims, is claimed for a pen for applying a coloring and / or cosmetic substance, with a lead made of the substance to be applied and a one-piece injection-molded sleeve encasing the lead made of a thermoplastic material which consists of a mixture of a first and a second plastic phase, and which is characterized in that after the outer circumferential surface has been cut in such a way that a chip protrudes from the outer circumferential surface, a skin can be pulled off the surface of the sleeve with the bare hand by pulling on the chip.

[0144] Independent protection, possibly also enriched with further features from the above description and / or the already existing claims, is claimed for a pen for applying a coloring and / or cosmetic substance, with a lead made of the substance to be applied and a one-piece injection-molded sleeve encasing the lead made of a thermoplastic material consisting of a mixture of a first and a second plastic phase, the pen being characterized in that its sleeve has a structure of two layers that can be separated from one another by hand, the layer closest to the surface preferably being thinner of these two layers.

[0145] Independent protection, possibly also enriched with further features from the above description, is provided for a pen for applying a coloring and / or cosmetic substance, with a lead made of the substance to be applied and a one-piece injection-molded sleeve encasing the lead made of a thermoplastic material which consists of a mixture of a first and a second plastic phase and which is characterized in that its sleeve, seen in the radial direction, has an outer enrichment zone with a higher concentration of the first plastic phase than in the central region.

[0146] It should be noted that the formation of an internal enrichment zone can possibly be achieved by appropriate temperature control on the inner circumference of the sleeve. Where this requirement applies, the above statements apply mutatis mutandis; only specific restrictions based on the internal enrichment zone (which is not present in this variant or is purely optional) are omitted.

[0147] Independent protection, possibly also enriched with further features from the above description and / or the already existing claims, is granted for a pen for applying a coloring and / or cosmetic substance, with a lead made of the substance to be applied and a one-piece injection-molded sleeve encasing the lead made of a thermoplastic material which consists of a mixture of a first and a second plastic phase and which is characterized in that its sleeve, seen in the radial direction, has an internal enrichment zone with a higher concentration of the first plastic phase than in the central region.

[0148] It should be noted that the formation of an external enrichment zone can, if necessary, be achieved by appropriate temperature control on the outer circumference of the sleeve. The heat energy no longer required after injection into the cavity is then essentially extracted from the plastic mass of the sleeve via its inner circumferential surface. Where this claim applies, the above statements apply mutatis mutandis; only specific restrictions based on the external enrichment zone (which is not present or purely optional in this variant) are omitted.

[0149] Further features of the invention of the pen according to the invention or the claim and the method provided for its manufacture are as follows.

[0150] According to the invention, the pin can be distinguished by the material system forming the sleeve being adjusted so that the first plastic phase has a weight fraction of at least 45 wt.%, better at least 55 wt.%.

[0151] According to the invention, the pin can be distinguished by the fact that the upper limit for the first plastic phase in the mixture ready for injection is 85 wt.%, better 70 wt.%.

[0152] According to the invention, the pin can be distinguished by the sleeve having an arithmetically averaged gloss level GU of more than 30 GU, better more than 40 GU, on the outer peripheral surface.

[0153] According to the invention, the pin can be distinguished by the sleeve having a structure of two separable layers, wherein preferably the layer closest to the surface of these two layers is thinner.

[0154] According to the invention, the pen can be distinguished by the plastic sleeve being made of non-foamed plastic material.

[0155] According to the invention, the pin can be distinguished by the sleeve being designed as a tube that is open on both ends.

[0156] According to the invention, the pin can be distinguished by the sleeve tapering conically at one end, preferably with a cone angle (Pi) of 25° to 35° to the longitudinal axis L of the sleeve.

[0157] According to the invention, the pin can be distinguished by the sleeve having a shoulder with a reduced diameter at one end.

[0158] According to the invention, the pin can be distinguished by an end cap being attached to the end of the pin and preferably to the shoulder, which end cap closes one end of the sleeve.

[0159] According to the invention, the pin can be raised by ejecting the finished injection-molded sleeve from the mold in the direction of its longitudinal axis.

[0160] According to the invention, the pen can be distinguished by the fact that the lead receptacle in the center of the sleeve is represented by a pin forming the mold core, together with which the sleeve is retracted when the sleeve is ejected from the injection mold.

[0161] According to the invention, the pin can be distinguished by the surface of the injection mold forming the outer peripheral surface having a roughness depth Rz ≤ 5 µm.

[0162] According to the invention, the pencil can be distinguished by the lead being cast by inserting the sleeve into a mold which seals the sleeve at its tapered end and reproduces the later shape of the unused lead tip and into which the lead-forming mass is poured at the other end of the sleeve. LIST OF REFERENCE SYMBOLS

[0163] 1Pin 2Sleeve 3Cross-section of the sleeve 4Outer circumference 5Inner circumference 6Outer enrichment zone 7Inner enrichment zone 8Lead 9Seat 10End cap 11Silicone plug 12Cone 100Measuring point 1 200Measuring point 2 LLongitudinal axis of the pin and its sleeve SSpan DSkin thickness ATemp length PiCone angle

Claims

1. Pen (1), in which a first and a second plastic phase are combined in the pen, the plastic phases differing in polarity and being either weakly polar with an electronegativity difference ΔEN in the range of 0.3 ≤ ΔEN ≤ 0.5 or strongly polar with an electronegativity difference ΔEN in the range of 0.5 < ΔEN ≤ 1.7, characterized in that the first plastic phase or the second plastic phase comprises at least one weakly polar plastic with an electronegativity difference ΔEN in the range of 0.3 ≤ ΔEN and ≤ 0.5.

2. Pen (1) according to one of the preceding claims, characterized in that the first plastic phase comprises at least one strongly polar plastic with an electronegativity difference ΔEN in the range of 0.5 < ΔEN and ≤ 1.7.

3. Pen (1) according to one of the preceding claims, characterized in that the second plastic phase comprises at least one strongly polar plastic with an electronegativity difference ΔEN in the range of 0.5 < ΔEN ≤ 1.7.

4. Pen (1) according to one of the preceding claims, characterized in that the first plastic phase comprises an AES or preferably a SAN.

5. Pen (1) according to one of the preceding claims, characterized in that the second plastic phase comprises a TPE or preferably a TPC-ET.

6. Pen (1) according to one of the preceding claims, characterized in that the first plastic phase comprises a strongly polar structural polymer, preferably a PET, PCT, PBT, or PMMA and / or in that the second plastic phase comprises a weakly polar TPE or preferably a TPV or TPO.

7. Method for producing a pen (1) according to one of the preceding claims with a sleeve (2), whereby each a first and a second plastic phase are combined in the pen (1), the plastic phases differing in polarity and being either weakly polar with an electronegativity difference ΔEN in the range of 0.3 ≤ ΔEN ≤ 0.5 or strongly polar with an electronegativity difference ΔEN in the range of 0.5 < ΔEN ≤ 1.7, and characterized in that the first plastic phase or the second plastic phase comprises at least one weakly polar plastic with an electronegativity difference ΔEN in the range of 0.3 ≤ ΔEN and ≤ 0.5.

8. Method according to claim 7, characterized in that the injection mold does not comprise a depiction of a parting line on the outer circumferential surface of the sleeve (2).