Articles made from heavy plastic materials

Abstract

The present invention relates to an article made from a material comprising a metal and / or ceramic filler present in an amount greater than 50% and not greater than 85% by weight, at least one polymer present in an amount greater than 15% and not greater than 50% by weight, and optionally at least one coupling agent present in an amount not greater than 0% and less than 10% by weight, wherein the polymer (4) is bonded to the filler (2) and, optionally, to the coupling agent (3) by one or more bonds selected from hydrogen bonds, coordinate bonds, and ionic bonds. The present invention also relates to a method for producing the article by injection molding or 3D printing.

Description

Technical Field

[0001] Field of the Invention The present invention relates to articles, for example, timepiece parts made of heavy plastic materials and resistant to impact. The present invention also relates to a method for manufacturing such articles made of heavy plastic.

Background Art

[0002] Many exterior parts such as cases and bands (bracelets) are made of plastic materials. These parts are manufactured by molding, which has the advantage of obtaining various shapes without any rework. Parts made of these plastic materials have a density close to 1 and are therefore characterized by being lightweight. This can be a drawback for users who want to wear a wristwatch with a certain weight on their wrist.

[0003] To mitigate this drawback, for example, in European Patent No. 2482142, it has been proposed to manufacture timepiece parts made of a plastic material filled with a high-density metal powder such as tungsten powder, regardless of whether it is a movement or an exterior part. These parts are manufactured by injection molding, which maintains the advantage of molding in a mold without subsequent rework and at the same time enables an increase in density.

[0004] Therefore, these materials combine certain advantages of plastics such as ease of injection molding with advantages of metals such as density, a cool touch, and a metallic appearance.

[0005] However, in relation to the polymer matrix used, a decrease in breaking strength and elongation can be observed in these materials. This decrease is due to the insufficient binding force of the material caused by the incorporation of micrometer-sized metal powder into the nanometer-sized polymer chains. Therefore, in the case of materials containing a metal (or ceramic) filler, a polyolefin (polyethylene, polypropylene) as a polymer, and a polyurethane as a coupling agent, it is observed that this reduces the properties due to the insufficient binding force of the material.

[0006] This decrease in mechanical properties will affect the impact absorption capacity of the material. Therefore, this type of material is not suitable for applications that require impact resistance, such as in the field of watches for manufacturing cases, etc.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

[0008] An object of the present invention is to propose a novel composition of a multi-plastic material that can improve the binding force of the material, thereby improving the mechanical properties of the material.

[0009] The present invention has particularly interesting applications in the field of watches, however, the present invention is not limited to such applications.

[0010] For this purpose, the present invention proposes an article made of a material containing the following weight percentages based on 100% of the total weight: - A filler made of a metal and / or ceramic material, having a density of 3 g / cm 3 or more, wherein the filler is present in a proportion of more than 50% by weight and up to 85% by weight, - At least one polymer present in a proportion of 15% by weight or more and 50% by weight or less, - Optionally, at least one coupling agent present in a proportion of 0% by weight or more and less than 10% by weight, - Optionally, at least one reinforcing material present in a proportion of 0 to 10% by weight, - Optionally, at least one dye present in a proportion of 0 to 5% by weight, - Optionally, at least one diluent and / or at least one plasticizer present in a proportion of 0 to 5% by weight.

[0011] In the present invention, when the material contains at least one coupling agent, the polymer is bonded to the filler and / or each coupling agent is bonded to the filler and the polymer by one or more of hydrogen bonds, coordination bonds or ionic bonds.

[0012] These bonds are formed between the oxidized surface of the filler and / or the electron holes present on the surface and the groups of the polymer and / or the coupling agent. For this purpose, the polymer and / or the coupling agent hold one or more of the following groups: NH x , OH, COC, C=O, COOH. The bonds of these fillers, polymers and, where applicable, coupling agents make it possible to ensure good bonding strength of the material. They are characterized by having an interaction energy of usually 100 kJ / mol or less than 50 kJ / mol, which makes it possible to break the bonds during the temperature rise during production, thereby ensuring a better mixture and better bonding strength of the material after cooling and reformation of the bonds.

[0013] Therefore, the developed material has sufficient rigidity with a Young's modulus of 2.5 GPa or more, sufficient elongation at break of 5% or more and a breaking point load of 30 MPa or more for watch applications. Furthermore, it has good toughness and a density of 2 to 7 g / cm 3 ³.

[0014] Furthermore, the present invention relates to a method for manufacturing this material by molding, by injection or by 3D printing.

[0015] The method is such that the base material for the filler is a polymer and / or, if present, a coupling agent, and a filler with a surface sufficiently reactive to form hydrogen, ionic and / or coordination bonds is obtained, with a BET of 0.01 m 2 / g, preferably 2 m 2 / g, more preferably 5 m 2 / g or more in the form of a powder. Whatever the form of the ceramic (oxide, nitride or carbide) or metal (steel, tungsten, etc.), the reactive surface thus contains hydroxides, oxides and / or electron holes.

[0016] Other features and advantages of the present invention will become apparent in the following description of the preferred embodiments presented non - limitatively with reference to the accompanying drawings.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0018] The present invention relates to an article made from a composite material including a plastic material and a metal or ceramic material. For example, the article can be a component such as a wristwatch, jewelry, bracelet, etc. The article can also be a component of a bezel, for example, a mount, an arm, a shoe.

[0019] Without being limiting or inclusive, the articles according to the present invention may also form components or the whole of sports goods, cooking utensils, musical goods or instruments, leather products or fashion accessories, automotive parts or aircraft parts, parts for electronic goods (e.g., phone protection cases, computer keyboards, keys of computer keyboards, audio headsets, etc.), writing utensils, etc. Conveniently, the article is a component that functionally requires resistance to specific impacts and shocks.

[0020] In certain horological fields, the article may be, for example, exterior parts such as cases, back covers, bezels, push buttons, bracelet links, dials, watch hands, dial indexes, etc. By way of example, Case 1 made from the material according to the present invention is shown in FIG. 1. In an example of another embodiment (not shown), the article according to the present invention may be, for example, a component of a movement such as a plate.

[0021] In the present invention, the article is made from a material comprising at least two components: a filler (metal and / or ceramic), and a polymer. Thus, the material may be considered a composite material. Optionally, if the physico-chemical interaction between the filler and the polymer is not sufficient, the material may comprise one or more coupling agents. Optionally, the material may include a reinforcing agent. Optionally, the material may also include one or more dyes. Optionally, the material may also include a diluent and / or a plasticizer.

[0022] The filler may be metal and / or ceramic. As the metal material, it may relate to conventional carbon steel, stainless steel, copper, copper alloy, titanium, titanium or tungsten alloy. It is preferably related to nickel-free stainless steel. As the ceramic material, it may relate to carbides, nitrides or oxides such as ZrO2, CeO2, ZnO, etc. It also relates to a filler containing a mixture of metal and ceramic materials.

[0023] The filler as a whole is the most massive, but is 85% by weight or less. Accordingly, the filler is 50 - 85% by weight (excluding the lower limit), for example, 50 - 75% by weight or 50 - 65% by weight (excluding the lower limit). Preferably, the filler is in a proportion of 60 - 80% by weight, and even more preferably 65 - 75% by weight. In the present invention, regardless of the type of the metal or ceramic filler, the filler is introduced during production in the form of a powder having a high specific surface area (≧0.01 m 2 / g) on its surface where, in fact, without special treatment, changes in its composition and / or defects should occur. It may relate to oxides or hydroxides present on the oxidized surface of defects such as powders and electron holes, which enable them to interact with the polymer and / or, if present, the coupling agent through various bonds. FIG. 2 thus shows the interaction formed between the surface of the filler 2, the coupling agent 3, and the polymer 4.

[0024] The material contains a filler and / or, if present, a coupling agent and one or more polymers capable of forming hydrogen, ionic, and / or coordination bonds. All these physicochemical bonds typically have the characteristic of having a low interaction energy of 5 - 100 kJ / mol, which enables the intermolecular bonds to be broken during the temperature rise during the injection or 3D printing of the material, and after the injection or 3D printing, these physicochemical bonds are restored during the cooling of the material. This property enables better mixing, better compatibility between components, and as a result, better binding force of the material at the molecular scale, as well as better overall binding force of the material.

[0025] The polymer or all polymers are in a proportion of 15 - 50% by weight (excluding the upper limit) of the material, for example, 25 - 50% by weight or even 35 - 50% by weight (excluding the upper limit). Preferably, the polymer or all polymers are present in a proportion of 20 to 40% by weight of the material, more preferably 25 to 35% by weight.

[0026] To form hydrogen bonds, the polymer contains a hydrogen bond donor containing a group having a hydrogen atom such as an NH or OH group and a hydrogen bond acceptor containing a group having an atom with a higher electronegativity than hydrogen such as nitrogen, oxygen or a halogen atom such as fluorine, chlorine, bromine. The hydrogen bonds are formed with the hydroxides and oxides present on the oxidized surface of the metal or ceramic filler. For example, the hydroxide groups on the surface of the filler interact with the C=O, R-OH, COC, R-NH x R’ groups of the polymer. The hydrogen bond donor and acceptor are preferably adjacent on the polymer chain. Further, by way of example, the polymer may thus be a polyamide having the R-C(=O)-NH-R’ pattern having a C=O group containing a binding acceptor oxygen atom and an N-H group containing an adjacent binding donor hydrogen atom.

[0027] The ionic bonds within the scope of the present invention result from the interaction between a negatively charged base functional group and a positively charged acid functional group. The bond is formed by the movement of H + ions from the OH groups on the surface of the ionic metal or ceramic filler in the direction of the polymer. For example, the polymer may contain NH x groups, more specifically polyamines, and after the acid-base reaction, R-NH x+1 -R’ + / MO - is obtained.

[0028] Coordinate bonding is a special type of covalent bond, where, contrary to the conventional covalent bond where electrons are derived from each bonding atom, the shared electron pair is derived from only one of the atoms. In the present invention, this bond more specifically means a Lewis base formed by a polymer bonded to an electron hole on the surface of a filler that forms a Lewis acid. Any functional group-retaining polymer containing a bond pair-holding atom can share this pair in order to "stabilize" the electron hole. For example, it can be related to the nitrogen or oxygen non-bonding pair in R(C=O)NR’, RO(C=O)NR’, and R(C=O)OR’. The polymer can also hold amine (NH x ) or carboxylic acid (COOH) functional groups that can form a bond with an electron hole on the surface of the filler. For example, polyurethane and polyester can be mentioned.

[0029] The material can contain a coupling agent in a proportion of 0% to less than 10%, preferably 0.1 to 10%, more preferably 0.1 to 5%, and even more preferably 0.5 to 3%. The coupling agent can also bond the filler and the polymer by one or more bonds selected from hydrogen, ionic, and coordinate bonds as described above. In the presence of the coupling agent, the bonds form bonds that are not necessarily direct bonds between the coupling agent and the filler, between the coupling agent and the polymer, and between the filler and the polymer. For the polymer, the coupling agent contains at least one group selected from C=O, COC, OH, NH x or, similarly, COOH. An example regarding hydrogen, ionic, and coordinate bonds can be related to a polyurethane having an R-O-C=O-NH-R’ pattern. Preferably, the coupling agent has a long chain having a minimum of 20 carbon atoms. A further example regarding hydrogen, ionic, and coordinate bonds can be related to a hydroxy silane having an amine or amide functional group, preferably having a minimum of 20 carbon atoms on the chain. A further example can be related to ionic bonds including an acid-base reaction involving the transfer of H + ions from the OH groups on the surface of the filler that occurs during production between the filler and the coupling agent. Also, the coupling agent and R-COOH carboxylic acid and RCOO - / R’-NH x+1+ and R'-NH that forms a base x It may also be related to an ionic bond with a polymer containing one or each of other amine functional groups. Alternatively, the polymer and the coupling agent may be filled before being arranged to be present. In that case, for the above example, the coupling agent and the polymer each have RCOO - a base functional group, or R-NH x+1 + retains an acid functional group.

[0030] Optionally, the material may also contain a reinforcing material in a proportion of 0 to 10% by weight, preferably 1 to 6% by weight. The reinforcing material can exist in various forms, for example, in the form of fibers or particles. For example, the reinforcing material may be related to glass fibers, glass beads, carbon fibers, and / or aramid fibers having a fiber length of 300 μm, preferably 200 μm or less. The purpose of the reinforcing material is to improve the toughness of the material, limit the dropout of the material during injection, and / or improve the electrical conductivity of the material.

[0031] Optionally, the material may also contain one or more dyes in a total proportion of 0 to 5% by weight. The dyes may be organic dyes or inorganic dyes. For example, the dyes may be related to carbon black for black, diketopyrrolopyrrole for red (e.g., Irgazin Red K3840LW by BASF), copper phthalocyanine for blue (e.g., Helio Gen Blue K7096 by BASF), monoazo dyes for yellow (e.g., Palio Tol Yellow K1760 by BASF), etc.

[0032] Optionally, the material may also include plasticizers such as diluents and / or waxes (paraffins) or other coating resins (terpene-based, phenol-based, etc.) to facilitate application during manufacturing, and these diluents and plasticizers are all 0 to 5% by weight.

[0033] By way of example, and as shown in FIG. 3, the material comprises a metal filler M and / or a ceramic filler 2, together with a polyamide as the polymer 4 and preferably a polyurethane as the coupling agent 3 containing at least 20 carbon atoms. In this example, the hydrogen bonds between the polymer, the coupling agent and the filler are represented by dotted lines. More specifically, in the case of this composition, the material comprises, based on a total of 100% by weight, a metal filler such as stainless steel and / or a ceramic such as zirconium oxide in a proportion of 65 to 80% by weight, preferably 65 to 75% by weight, a polyamide in a proportion of 19.5 to 34.5% by weight, preferably 24 to 34% by weight, and a polyurethane in a proportion of 0.5 to 5% by weight, preferably 1 to 3.5% by weight.

[0034] In one example, the material comprises a metal and / or a ceramic filler and a polyurethane, and the polyurethane functions as both a polymer and a coupling agent. In this example, a coupling agent separate from the polymer is thus not necessary. The reason is that the interaction between the filler and the polymer is sufficient to ensure good bonding of the material at the last point of the process. In one example, the material comprises a metal and / or a ceramic filler and a polyurethane, together with a polyamide as the polymer and a hydroxysilane having an amine or amide functional group as the coupling agent, and the coupling agent preferably contains at least 20 carbon atoms. In one example, the material comprises a metal and / or a ceramic filler, together with a polyester as the polymer and a hydroxysilane having an amine or amide functional group as the coupling agent, and the coupling agent preferably contains at least 20 carbon atoms.

[0035] The article is manufactured by injection molding or 3D printing. The method is characterized by the BET of the filler powder which needs to be sufficient to obtain a reactive surface. More specifically, the base material for the filler is a powder having a BET specific surface area of 0.01 m 2 / g, preferably 2 m 2 / g, more preferably 5 m 2 / g or more, measured according to the standard ISO9277 of 2010.

[0036] In the case of injection molding, the manufacturing method includes the following steps regarding the above-mentioned filler, polymer, coupling agent, reinforcing material and pigment: a) Preparing granules of several millimeters in size, containing the following by weight percentage: - A metal and / or ceramic filler having a density of 3 g / cm³ or more, the filler being present in a proportion of more than 50% by weight and 85% by weight or less, preferably 60 - 80%, more preferably 65 - 75%, 3 - A polymer present in a proportion of 15% by weight or more and 50% by weight or less in total, preferably 20 - 40% by weight, more preferably 25 - 35% by weight, - Optionally, at least one coupling agent present in a proportion of 0% by weight or more and less than 10% by weight, preferably 0.1 - 10% by weight, more preferably 0.1 - 5% by weight, even more preferably 0.5 - 3% by weight, - Optionally, a reinforcing material present in a proportion of 0 - 10% by weight, - Optionally, a pigment present in a proportion of 0 - 5% by weight, - Optionally, a diluent and / or plasticizer or a mixture of a diluent and / or plasticizer, the diluent and / or plasticizer or the mixture of the diluent and / or plasticizer being present in a proportion of 0 - 5%, - Optionally, a diluent and / or plasticizer or a mixture of a diluent and / or plasticizer, the diluent and / or plasticizer or the mixture of the diluent and / or plasticizer being present in a proportion of 0 - 5%, b) Injecting the granules to form an article. The injection is carried out into the mold at a temperature of 60 - 100°C, preferably 70 - 80°C, while during injection, the material has a temperature of 200 - 300°C, and preferably 250°C - 300°C.

[0037] In step a), the granules can be produced by cutting the beads by extrusion from the raw materials described above. Preferably, if present, the coupling agent is introduced into the hopper of the extruder in the first stage, separately or together with the polymer granules, before the introduction of the metal or ceramic powder into the extruder in the second stage. If the coupling agent is introduced separately, it can be introduced in the form of a powder having a d90 of 500 μm, and preferably 315 μm or less, or in liquid form. The pigment can preferably be introduced during extrusion, in the second stage. It is also conceivable to mix it with the polymer granules immediately before extrusion.

[0038] In one variant, the metal, or ceramic material and, if present, the coupling agent are introduced into the hopper of the extruder in the first stage, together with the coupling agent, so as to coat the metal or ceramic powder, before introducing the polymer and the reinforcing material. Alternatively, the article can be manufactured by 3D printing, such as by FDM (Fused Deposition Modeling).

[0039] The article thus obtained comprises a plastic material comprising a metal, and / or a ceramic material and a polymer, and optionally a coupling agent, together with the product resulting from the reaction between the filler, the polymer and the coupling agent during extrusion or injection. The article also comprises the reinforcing material and the pigment, if present. The article has a Young's modulus of 2.5 GPa or more, an elongation at break of 5% or more and a breaking load of 30 MPa or more, and these properties are measured according to the standard ISO527-1A of 2019.

[0040] As an example, tests were carried out to manufacture by injection molding of the case, based on cylindrical granules having diameters and lengths of about 4 mm and 1.5 mm respectively. Tables 1 and 2 below give two examples, and Table 3 shows the properties obtained before and after aging for 24 hours at 60 °C in a ventilated furnace without humidity control. The resilience test on the case by pendulum impact further demonstrated the good toughness of the case made of the above composition.

[0041] [Table 1]

[0042] [Table 2]

[0043] [Table 3]

Claims

1. 2 to 7 g / cm ３ An article made of a material having a density of, wherein the material comprises, based on a total of 100% by weight: -3 g / cm ３ A filler (2) made of a metal and / or ceramic material having the above density, wherein the filler (2) is present in a proportion of more than 50% by weight and at most 85% by weight. - At least one polymer (4) present in a proportion of 15% by weight or more and 50% by weight or less, - At least one coupling agent (3) present in a proportion of more than 0% by weight and less than 10% by weight, - Optionally, at least one reinforcing material present in a proportion of 0 to 10% by weight, - Optionally, at least one dye present in a proportion of 0 to 5% by weight, - Optionally, at least one diluent and / or plasticizer present in a proportion of 0 to 5% by weight, comprising, wherein the polymer (4) is bonded to the filler (2), and the coupling agent (3) is bonded to the polymer (4) and the filler (2) respectively by hydrogen bonds, wherein the polymer (4) and the coupling agent (3) contain an NHx group which is at least one hydrogen bond donor and a C=O group which is at least one hydrogen bond acceptor, and the coupling agent (3) also contains at least one COC group bonded to the hydroxide and oxide groups on the surface of the filler (2), an article characterized thereby.

2. The article according to claim 1, characterized in that the filler (2) is present in a proportion of 60 to 80% by weight and the polymer (4) is present in a proportion of 20 to 40% by weight.

3. The article according to claim 1, characterized in that the filler (2) is present in a proportion of 65 to 75% by weight and the polymer (4) is present in a proportion of 25 to 35% by weight.

4. The article according to claim 1, characterized in that the coupling agent (3) is present in a proportion of 0.1 to 10% by weight.

5. The article according to claim 4, characterized in that the coupling agent (3) is present in a proportion of 0.1 to 5% by weight.

6. The article according to claim 4, characterized in that the coupling agent (3) is present in a proportion of 0.5 to 3% by weight.

7. The article according to claim 1, characterized in that the hydrogen bond donor and acceptor of each of the groups are adjacent on the polymer (4) and / or the coupling agent (3).

8. The article according to claim 1, characterized in that the polymer (4) is a polyamide.

9. The article according to claim 1, characterized in that the coupling agent (3) is a polyurethane.

10. The polymer (4) is bonded to the filler (2), and the coupling agent (3) is bonded to the polymer (4) and the filler (2) respectively by one or more ionic bonds. The article according to claim 1, characterized in that.

11. The polymer (4) is bonded to the filler (2), and the coupling agent (3) is bonded to the polymer (4) and the filler (2) respectively by one or more bonds, and one of the bonds is a coordination bond. The article according to claim 1, characterized in that.

12. The polymer (4) and / or the coupling agent (3) has a carboxylic acid or amine functional group that forms a coordination bond with the electron holes on the surface of the filler (2). The article according to claim 11, characterized in that.

13. The coupling agent (3) contains at least 20 carbon atoms. The article according to claim 11, characterized in that.

14. The material includes the filler (2) together with polyamide as the polymer (4) and polyurethane as the coupling agent (3). The article according to claim 1, characterized in that.

15. The material contains the filler (2) at a ratio of 65 to 80% by weight, the polymer (4) at a ratio of 19.5 to 34.5% by weight, and the coupling agent (3) at a ratio of 0.5 to 5% by weight, based on a total of 100% by weight. The article according to claim 14, characterized in that.

16. The material contains the filler (2) at a ratio of 65 to 75% by weight, the polymer (4) at a ratio of 24 to 34% by weight, and the coupling agent (3) at a ratio of 1 to 3.5% by weight. The article according to claim 15, characterized in that.

17. The reinforcing material is present at a ratio of 1 to 6% by weight. The article according to claim 1, characterized in that.

18. The reinforcing material is formed from glass fiber, glass bead, carbon fiber and / or aramid fiber. The article according to claim 1, characterized in that.

19. The article according to claim 1, characterized in that it relates to an exterior part or a movement of a watch.

20. a) A step of preparing the base materials of the filler (2), the polymer (4), the coupling agent (3), and optionally the reinforcing material, diluent and / or plasticizer, according to the following: - The filler (2) is made of a metal and / or ceramic material having a density of 3 g / cm ３ or more, and the filler (2) is present in a proportion of more than 50% by weight and 85% by weight or less. - The polymer (4) is present at a ratio of 15% by weight or more and 50% by weight or less. - The coupling agent (3) is present in a proportion of more than 0% by weight and less than 10% by weight. - The reinforcing material is present in a proportion of 0 to 10% by weight. - The pigment is present in a proportion of 0 to 5% by weight. - The diluent and / or the plasticizer is present in a proportion of 0 to 5% by weight. b) A step of molding the base material by an injection molding technique or a 3D printing technique to produce the article. A method for manufacturing the article according to claim 1, comprising: The base material for the filler (2) has a BET specific surface area of 0.01 m ２ / g or more, and after the preforming step, the polymer (4) is bonded to the filler (2), and the coupling agent (3) is bonded to the polymer (4) and the filler (2), respectively, by one or more bonds selected from hydrogen bonds. A method characterized by that.

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