An article made of a heavy plastic material

Abstract

The present invention relates to an article made of the following materials, by weight, the materials comprising: a metal and / or ceramic filler present in a percentage greater than 50% and less than or equal to 85%, at least one polymer present in a percentage greater than or equal to 15% and less than or equal to 50%, and optionally at least one coupling agent present in a percentage greater than or equal to 0% and less than 10%, characterized in that the polymer (4) is bonded to the filler (2) and optionally the coupling agent (3) by one or more bonds selected from hydrogen bonds, coordination bonds and ionic bonds. The present invention also relates to a method for manufacturing the article by injection molding or 3D printing.

Description

Technical Field

[0001] The present invention relates to an article, for example, a clock component, made of a heavy plastic material and resistant to impact.

[0002] The present invention also relates to a method for manufacturing such an article made of heavy plastic. Technical Background

[0003] Many external components, such as intermediate components and watch straps, are made of plastic materials. These components can be produced by molding methods, which have the advantage of obtaining different shapes without any rework operations. These components made of plastic materials have a density close to 1 and are therefore lightweight. This may constitute a disadvantage for users who wish to wear a watch with a certain weight on their wrist.

[0004] To overcome this disadvantage, it has been proposed, for example, in document EP 2 482 142, to produce clock components made of plastic materials filled with high-density metal powders such as tungsten powder, whether for the movement or external parts. These components are produced by injection molding, which can maintain the advantages of molding in a mold while increasing the density without subsequent rework.

[0005] Therefore, these materials combine certain advantages of plastics, such as ease of injection molding, and advantages of metals, such as density, cold touch, and metallic appearance.

[0006] However, a decrease in fracture strength and elongation related to the polymer matrix used can be observed in these materials. This decrease is attributed to the lack of cohesion of the material due to the incorporation of micron-sized metal powders into nanometer-sized polymer chains. Therefore, it has been observed that for materials containing metal (or ceramic) fillers, polyolefins (polyethylene, polypropylene) as polymers, and polyurethane as a coupling agent, this decrease in performance is caused by the lack of cohesion of the material.

[0007] 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, for example, in the clock field for producing intermediate components, etc. Summary of the Invention

[0009] The object of the present invention is to propose a new composition of heavy plastic material that can improve the cohesion of the material and thus improve its mechanical properties.

[0010] The present invention has a particularly interesting application in the clock field; however, the present invention is not limited to this application.

[0011] To this end, the present invention proposes an article made of a material that, by total weight of 100%, comprises:

[0012] - A filler, made of a metal and / or ceramic material with a density greater than or equal to 3 g / cm 3 , and the filler is present in a percentage greater than 50% and less than or equal to 85%,

[0013] - At least one polymer, present in a percentage greater than or equal to 15% and less than or equal to 50%,

[0014] - Optionally at least one coupling agent, present in a percentage greater than or equal to 0% and less than 10%,

[0015] - Optionally at least one reinforcing agent, present in a percentage between 0 and 10%,

[0016] - Optionally at least one pigment, present in a percentage between 0 and 5%,

[0017] - Optionally at least one diluent and / or one plasticizer, present in a percentage between 0 and 5%.

[0018] According to the present invention, the polymer is bonded to the filler by one or more of hydrogen bonds, coordination bonds or ionic bonds, and / or when the material includes at least one coupling agent, the coupling agent is bonded to the filler and the polymer respectively.

[0019] These bonds are established between the oxidized surface of the filler and / or the electronic vacancies present on the filler surface and the groups of the polymer and / or the coupling agent. For this purpose, the polymer and / or the coupling agent is a carrier of, for example, one or more of the following groups: NH x , OH, COC, C=O, COOH. These bonds that bind the filler, the polymer and, if appropriate, the coupling agent make it possible to ensure good cohesion of the material. They are characterized by an interaction energy that is usually less than 100 kJ / mol or even 50 kJ / mol, which makes it possible to break the bonds between molecules during the temperature increase in the manufacturing process, thus ensuring better mixing and better cohesion of the material after cooling and re-forming the bonds.

[0020] For watch applications, the material thus developed has sufficient stiffness with a Young's modulus greater than or equal to 2.5 GPa, sufficient elongation at break greater than or equal to 5%, and a fracture load greater than or equal to 30 MPa. In addition, it also has good toughness and a density between 2 and 7 g / cm 3 .

[0021] In addition, the present invention relates to a method for manufacturing such a material by molding, injection or 3D printing.

[0022] The method is characterized in that the raw material of the filler is in powder form, which has a BET of greater than or equal to 0.01 m 2 / g, preferably 2 m 2 / g, more preferably 5 m 2 / g, so as to obtain a filler with a sufficiently reactive surface to form hydrogen bonds, ionic bonds and / or coordination bonds with the polymer and / or coupling agent, if the latter is present. Regardless of the type of ceramic (oxide, nitride or carbide) or metal (steel, tungsten, etc.), its reactive surface includes hydroxides, oxides and / or electron vacancies.

[0023] Other features and advantages of the present invention will become apparent in the following description of the preferred embodiments, presented by way of non-limiting example with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A clock showing an intermediate assembly made of a heavy plastic material according to the present invention.

[0025] Figure 2 Illustrates the interaction between the filler surface, the coupling agent and the polymer.

[0026] Figure 3 Schematically illustrates the hydrogen bonds established between the filler, the coupling agent and the polymer. SUMMARY OF THE INVENTION

[0027] The present invention relates to an article made of a composite material comprising a plastic material and a metal or ceramic material.

[0028] For example, the article can be a component of a watch, jewelry, bracelet, etc.

[0029] The article can also be a component of a bezel, such as a frame, arm, washer (shoe).

[0030] In a non-limiting and non-exhaustive manner, the article according to the present invention can also be a component of sports goods, cooking utensils, musical instruments or musical supplies, leather goods or clothing, automotive or aviation components, electronic supplies (such as phone cases, computer keyboards, computer keyboard keys, audio headphones, etc.) and writing supplies, etc., or form an entirety.

[0031] Advantageously, the article is a component whose function requires a certain degree of impact resistance and shock resistance.

[0032] In the specific field of horology, the article can be, for example, an external component, such as an intermediate assembly, a case back, a bezel, a button, a link of a chain strap, a dial, a hand, a dial marker, etc.

[0033] By way of illustration, the intermediate assembly 1 made of the material according to the present invention is asFigure 1 as shown

[0034] According to another embodiment of the embodiment (not shown), the article according to the invention may be a component of a movement, for example, by way of example, a main plate.

[0035] According to the invention, the article is made of a material comprising at least two components including a filler, a metal and / or a ceramic, and a polymer. Thus, the material can be characterized as a composite material.

[0036] Optionally, if the physico-chemical interaction between the filler and the polymer is insufficient, the material may include one or more coupling agents.

[0037] Optionally, the material may include a reinforcing agent.

[0038] Optionally, the material may further include one or more pigments.

[0039] Optionally, the material may further include a diluent and / or a plasticizer.

[0040] The filler may be a metal and / or a ceramic.

[0041] For metal materials, it may relate to conventional carbon steel, stainless steel, copper, copper alloy, titanium, titanium or tungsten alloy. Preferably, it relates to nickel-free stainless steel.

[0042] For ceramic materials, it may relate to carbides, nitrides or oxides, such as ZrO2, CeO2, ZnO, etc.

[0043] It may also relate to a filler comprising a mixture of metal and ceramic materials.

[0044] The filler is preponderant in mass overall, but is less than or equal to 85% by weight. Thus, it is between 50% and 85% by weight (excluding the lower limit), for example between 50% and 75% or also between 50% and 65% (excluding the lower limit).

[0045] Preferably, its weight percentage is between 60% and 80%, even more preferably between 65% and 75%.

[0046] According to the invention, the filler is introduced in the form of a powder having a high specific surface area (≥0.01 m 2 / g), in fact, without special treatment, regardless of the type of metal or ceramic filler, there will be changes in its surface composition and / or defects. It may relate to oxides or hydroxides present on the oxidized surface of the powder and defects such as electron vacancies, which will make it possible to interact with the polymer and / or the coupling agent, if the latter is present, through various bonds. Thus, Figure 2Illustrates the interactions established between the surface of the filler 2, the coupling agent 3, and the polymer 4.

[0047] The material comprises one or more polymers capable of forming hydrogen bonds, ionic bonds, and / or coordination bonds with the filler and / or the coupling agent, when the coupling agent is present. All these physical chemical bonds are characterized by a low interaction energy, typically between 5 and 100 kJ / mol, which makes it possible to break the bonds between molecules during the temperature increase in the injection or 3D printing process of the material, and these physical chemical bonds are re-established during the cooling of the material after injection or 3D printing. This property enables better mixing between components, better compatibility, and thus better cohesion of the material at the molecular scale, and therefore better overall cohesion of the material.

[0048] The polymer or all polymers account for between 15% and 50% (excluding the upper limit) of the weight of the material, for example between 25% and 50% or also between 35% and 50% (excluding the upper limit).

[0049] Preferably, the polymer or all polymers account for between 20% and 40% of the weight of the material, more preferably between 25% and 35%.

[0050] To form hydrogen bonds, the polymer includes 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 more electronegative than hydrogen such as an atom in the group of nitrogen, oxygen, or halogen such as fluorine, chlorine, bromine, etc. The hydrogen bond is established with the hydroxides and oxides present on the oxidized surface of the metal or ceramic filler. For example, the hydroxide group on the filler surface interacts with the C=O, R-OH, COC, R-NH x R' groups of the polymer. Preferably, the hydrogen bond donor and acceptor are adjacent on the polymer chain. Still by way of example, the polymer can be a polyamide having the R-C(=O)-NH-R' pattern, thus, the C=O group includes the bond acceptor oxygen atom, and the N-H group includes the adjacent bond donor hydrogen atom.

[0051] The ionic bond within the scope of the present invention is generated by the interaction between a negatively charged basic functional group and a positively charged acidic functional group. The bond is established with the transfer of H + ions from the OH group on the surface of the metal or ceramic filler to the polymer. For example, the polymer can include NH x groups, more specifically polyamines, where R-NH x+1 -R'+ / MO- is obtained after an acid-base reaction.

[0052] A coordination bond is a special type of covalent bond in which the shared electron pair comes only from one of the bonded atoms, as opposed to a traditional covalent bond where the electrons come from each of the bonded atoms. According to the present invention, the bond more specifically relates to a Lewis base formed by a polymer and is related to the electron vacancies on the surface of the filler that forms a Lewis acid. Any functional group carrier polymer containing a non-bonding electron pair carrier atom can share this electron pair to "stabilize" the electron vacancies. For example, it can involve the nitrogen or oxygen non-bonding pairs in R(C=O)NR', RO(C=O)NR', and R(C=O)OR'. The polymer can also carry amine (NHx) or carboxylic acid (COOH) functional groups that can form such a bond with the electron vacancies on the filler surface. For example, polyurethane and polyester can be mentioned.

[0053] The material can include a coupling agent in a percentage between 0% and less than 10%, advantageously between 0.1% and 10%, more advantageously between 0.1% and 5%, and even more advantageously between 0.5% and 3%. The coupling agent can also be bonded to the filler and the polymer through one or more bonds selected from, for example, the above-mentioned hydrogen bonds, ionic bonds, and coordination bonds. Specifically, in the presence of the coupling agent, the bond is established between the coupling agent and the filler, and between the coupling agent and the polymer, respectively, without the need for a direct bond between the filler and the polymer. For the polymer, the coupling agent can include at least one group selected from C=O, COC, OH, NH x or COOH. As an example of hydrogen bonds, ionic bonds, and coordination bonds, it can involve a polyurethane having the R-O-C=O-NH-R' pattern. Preferably, the coupling agent has a long chain with at least 20 carbon atoms. Still as an example of hydrogen bonds, ionic bonds, and / or coordination bonds, it can involve a hydroxy silane having an amine or amide functional group and advantageously at least 20 carbon atoms in the chain. Still by way of example, it can involve an ionic bond where an acid-base reaction occurs between the filler and the coupling agent during the manufacturing process, accompanied by the transfer of H + ions from the OH groups on the filler surface. An ionic bond between the coupling agent and the polymer can also be involved, where the polymer includes one or the other of the R-COOH carboxylic acid and R'-NH x amine functional groups, and forms a base with RCOO- / R'-NH x+1 + obtained after the acid-base reaction. Alternatively, the polymer and the coupling agent can be pre-loaded before being present. In this case, for the above examples, the coupling agent and the polymer are carriers of the RCOO- basic functional group or R'-NH x+1 + acidic functional group, respectively.

[0054] Optionally, the material may also include a reinforcing agent in a weight percentage between 0 and 10%, advantageously between 1% and 6%. The reinforcing agent can exist in various forms, for example, in the form of fibers or particles. For example, it can involve glass fibers, glass beads, carbon fibers, and / or aramid fibers, with a fiber length less than or equal to 300 μm, preferably 200 μm. The purpose of the reinforcing agent is to improve the toughness of the material, limit the removal of the material during the injection process, and / or improve the electrical conductivity of the material.

[0055] Optionally, the material may also include one or more pigments, with a total percentage by weight between 0 and 5%. The pigment can be an organic or mineral pigment. For example, it can involve carbon black for black, diketopyrrolopyrrole for red (such as Irgazin Red K3840LW from BASF), copper phthalocyanine for blue (such as Heliogen Blue K7096 from BASF), monoazo pigment for yellow (such as Paliotol Yellow K1760 from BASF), etc.

[0056] Optionally, the material may also include a diluent and / or a plasticizer, such as wax (paraffin wax) or other applied resins (terpenes, phenolics, etc.), to facilitate the application during the manufacturing process, and all these diluents and plasticizers are in a weight between 0 and 5%.

[0057] For example, and as Figure 3 shown, the material includes a metal filler M and / or a ceramic filler 2, a polyamide as the polymer 4, and a polyurethane as the coupling agent 3 preferably having at least 20 carbon atoms. In this embodiment, the hydrogen bonds between the polymer, the coupling agent, and the filler are represented by dashed lines. More specifically, for this composition, in terms of 100% by weight percentage, the material includes a metal filler such as stainless steel and / or a ceramic such as zirconia in a percentage between 65% and 80%, preferably between 65% and 75%, a polyamide in a percentage between 19.5% and 34.5%, preferably between 24% and 34%, and a polyurethane in a percentage between 0.5% and 5%, preferably between 1% and 3.5%.

[0058] For example, the material includes a metal and / or a ceramic filler and a polyurethane, where the polyurethane serves as both the polymer and the coupling agent. Therefore, in this embodiment, a coupling agent different from the polymer is not required because the interaction between the filler and the polymer is sufficient to ensure good cohesion of the material at the end of the process.

[0059] For example, the material includes a metal and / or a ceramic filler, a polyamide as the polymer, and a hydroxy silane with amine or amide functional groups as the coupling agent, and the coupling agent advantageously contains at least 20 carbon atoms.

[0060] For example, the material comprises a metal and / or ceramic filler, a polyester as a polymer, and a hydroxy silane having amine or amide functional groups as a coupling agent, and the coupling agent preferably contains at least 20 carbon atoms.

[0061] The article is manufactured by injection molding or 3D printing. The characteristic of this method is that the BET of the filler powder must be sufficient to obtain a reactive surface. More specifically, the raw material for the filler is a powder having a specific surface BET of greater than or equal to 0.01 m 2 / g, preferably 2 m 2 / g, more preferably 5 m 2 / g, measured according to the ISO 9277 standard in 2010.

[0062] For the injection molding method, the manufacturing method includes the following steps involving the above-mentioned filler, polymer, coupling agent, reinforcing agent, and pigment:

[0063] a) Prepare granules of several millimeters, by weight, including:

[0064] - A metal and / or ceramic filler having a density greater than or equal to 3 g / cm 3 , and the filler is present in a percentage greater than 50% and less than or equal to 85%, preferably between 60% and 80%, more preferably between 65% and 75%,

[0065] - One or more polymers as a whole, present in a percentage greater than or equal to 15% and less than or equal to 50%, preferably between 20% and 40%, more preferably between 25% and 35%,

[0066] - Optionally at least one coupling agent, present in a percentage greater than or equal to 0% and less than 10%, advantageously between 0.1% and 10%, more advantageously between 0.1% and 5%, even more advantageously between 0.5% and 3%,

[0067] - Optionally a reinforcing agent, present in a percentage between 0 and 10%,

[0068] - Optionally one or more pigments, present in a percentage between 0 and 5%,

[0069] - Optionally a diluent and / or plasticizer or a mixture of diluent and / or plasticizer, present in a percentage between 0 and 5%.

[0070] b) Inject the granules to form the article. The injection is carried out in a mold at a temperature between 60 °C and 100 °C, preferably between 70 °C and 80 °C, while the temperature of the material during the injection process is between 200 °C and 300 °C, preferably between 250 °C and 300 °C.

[0071] In step a), the particles can be manufactured by cutting beads from the extrudate of the above raw materials. Advantageously, the coupling agent, if present, introduces the metal or ceramic powder in a second stage. Before that, in a first stage, it is introduced into the hopper of the extruder either alone or together with the polymer particles. When the coupling agent is introduced alone, it can be introduced in the form of a powder with a d90 less than or equal to 500 μm, preferably 315 μm, or in liquid form. The pigment can be introduced during the extrusion process and advantageously in the second stage. It is also conceivable to mix it with the polymer particles just before extrusion.

[0072] In one embodiment, the metal or ceramic material and the coupling agent (if present) are introduced into the hopper of the extruder in the first stage so as to coat the metal or ceramic powder with the coupling agent before introducing the polymer and the reinforcing agent.

[0073] Additionally, the article can be manufactured by 3D printing, for example by FDM (Fused Deposition Modeling).

[0074] The article thus obtained comprises a metal and / or ceramic material and a plastic material comprising a polymer, as well as a possible coupling agent, where the product results from the reaction between the filler, the polymer, and the coupling agent during extrusion or injection. It also includes a reinforcing agent and a pigment, if the pigment and the reinforcing agent are present.

[0075] Its Young's modulus is greater than or equal to 2.5 GPa, the elongation at break is greater than or equal to 5%, and the breaking load is greater than or equal to 30 MPa. These properties are measured according to the 2019 standard ISO 527-1A.

[0076] For example, tests were carried out to manufacture intermediate components by injection based on cylindrical particles with a diameter and length of approximately 4 mm and 1.5 mm, respectively. Taking the following Table 1 and Table 2 as two examples, the result characteristics before and after aging for 24 hours in a ventilated oven at 60 °C without humidity control are shown in Table 3. In addition, the good toughness of the intermediate components made of the above composition was also demonstrated by an impact pendulum elastic test on the intermediate components.

[0077] Table 1 - Example 1 - Composition

[0078]

[0079] Table 2 - Example 2 - Composition

[0080]

[0081] Table 3 - Characteristics of Example 1 and 2 - Before and after aging (in parentheses)

[0082] Rigidity - Young's modulus Elongation at break Breaking strain Example 1 3.0 GPa (3.1 GPa) 16.3％(15.4％) 55 MPa (55 MPa) Example 2 4.4 GPa (4.4 GPa) 9.7％(8.8％) 63 MPa (61 MPa)

Claims

1. An article made of a material having a density between 2 g / cm 3 and 7 g / cm 3 and, based on 100% by total weight, the material comprises: - Filler (2), the filler (2) is made of a metal and / or ceramic material with a density greater than or equal to 3 g / cm 3 , and the filler (2) is present in a percentage greater than 50% and less than or equal to 85%, - At least one polymer (4), which is present in a percentage greater than or equal to 15% and less than or equal to 50%, - At least one coupling agent (3), which is present in a percentage greater than 0% and less than 10%, - Optionally at least one reinforcing agent, which is present in a percentage between 0 and 10%, - Optionally at least one pigment, which is present in a percentage between 0 and 5%, - Optionally at least one diluent and / or plasticizer, which is present in a percentage between 0 and 5%, Through hydrogen bonds, 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, Characterized in that the polymer (4) and the coupling agent (3) comprise a hydrogen bond donor NH x group and a hydrogen bond acceptor C=O group, The coupling agent (3) further includes a COC group that interacts with hydroxides and oxides on the surface of the filler (2).

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

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

4. The article according to any one of claims 1 to 3, characterized in that, The coupling agent (3) is present in a weight percentage between 0.1% and 10%.

5. The article according to claim 4, characterized in that, The coupling agent (3) is present in a weight percentage between 0.1% and 5%.

6. The article according to claim 4, characterized in that, The coupling agent (3) is present in a weight percentage between 0.5% and 3%.

7. The article according to any one of claims 1 to 3, characterized in that, Hydrogen bond donor and acceptor groups are adjacent on the polymer (4) and / or the coupling agent (3) respectively.

8. The article according to claim 7, characterized in that, The polymer (4) is a polyamide.

9. The article according to claim 8, characterized in that, The coupling agent (3) is a polyurethane.

10. The article according to any one of claims 1 to 3, characterized in that, Also through ionic bonds, 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.

11. The article according to any one of claims 1 to 3, characterized in that, Also through coordination bonds, 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.

12. The article according to claim 11, characterized in that, The polymer (4) and / or the coupling agent (3) carry carboxylic acid or amine functional groups, and the carboxylic acid or amine functional groups form the coordination bonds with electron vacancies on the surface of the filler (2).

13. The article according to any one of claims 1 to 3, characterized in that, The coupling agent (3) includes at least 20 carbon atoms.

14. The article according to any one of claims 1 to 3, characterized in that, The material includes the filler (2), polyamide as the polymer (4), and polyurethane as the coupling agent (3).

15. The article according to claim 1, characterized in that, The material includes, for 100% of the percentage, the filler (2) in a percentage between 65% and 80%, the polymer (4) in a percentage between 19.5% and 34.5%, and the coupling agent (3) in a percentage between 0.5% and 5%.

16. The article according to any one of claims 1 to 2, characterized in that, The material includes the filler (2) in a percentage between 65% and 75%, the polymer (4) in a percentage between 24% and 34%, and the coupling agent (3) in a percentage between 1% and 3.5%.

17. The article according to any one of claims 1 to 3, characterized in that, The reinforcing agent is present in a weight percentage between 1% and 6%.

18. The article according to any one of claims 1 to 3, characterized in that, The reinforcing agent is formed by glass fibers, glass beads, carbon fibers, and / or aramid fibers.

19. The article according to any one of claims 1 to 3, characterized in that, It relates to components of the external part or of the watch movement.

20. A method of manufacturing an article according to any one of the preceding claims, comprising: a) a step of configuring the raw materials of the filler (2), the polymer (4), the coupling agent (3) and optionally the reinforcing agent, the pigment and the diluent and / or the plasticizer, wherein: - The filler (2) is made of a metal and / or ceramic material with a density greater than or equal to 3 g / cm 3 and the filler (2) is present in a percentage greater than 50% and less than or equal to 85%. - the polymer (4) is present in a percentage greater than or equal to 15% and less than or equal to 50%, - the coupling agent (3) is present in a percentage greater than 0% and less than 10%, - the reinforcing agent is present in a percentage between 0 and 10%, - the pigment is present in a percentage between 0 and 5%, - the diluent and / or plasticizer is present in a percentage between 0 and 5%, b) a step of shaping the raw materials by an injection molding technique or a 3D printing technique to produce the article The method is characterized in that the raw material of the filler (2) is a powder having a BET specific surface area of greater than or equal to 0.01 m 2 / g, and after the shaping step, the polymer (4) is bonded to the filler (2) by hydrogen bonds and the coupling agent (3) is bonded to the polymer (4) and the filler (2), respectively.

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