DESC:TECHNICAL FIELD

Present disclosure generally relates to a field of materials used in manufacturing technology. Particularly, but not limiting to, the present disclosure relates to a polymer material for straps of a timepiece. Further, embodiments of the present disclosure disclose composition of the polymer and a method of manufacturing the polymeric strap for the timepiece.

BACKGROUND

Straps for timepiece such as wrist watches may be made from several materials including leather, metal, cloth etc. These straps can be formed as a single piece that is connected on both ends to the watch, or they may alternatively be formed in two pieces, that are connected one each on either side of the watch. Such straps include an attachment mechanism that secures the watch on the arm of the user. Although watch straps have utility, they are also sometimes selected to match the style of the user. Generally, one end of the watch strap is connected to the watch and includes a bore or a loop through which a spring-loaded pin is inserted. The pin pivotally connects the end of the strap to a bezel of the watch by engaging corresponding openings formed in the bezel.

It is important that straps used in watches have to comply with the requirements of the Globally Harmonized System (GHS) of Classification. Accordingly, the manufactured straps must fulfill several criteria to be universally acceptable. For example, the straps should not be hazardous or toxic and must also be free from acute fish toxicity, acute toxicity for algae, acute bacterial toxicity etc. The straps must be soft to touch, should be flexible, must impart high resistance to tear and should preferably be resistant to bacterial fungi that grow due to moisture. The straps should also be able to withstand contact with the skin for a prolonged period of time, and hence should be biocompatible as well. Owing to these requirements, conventionally, the straps used in watches are majorly made of silicon material or universal thermoplastic polyurethane (TPU70). Since a silicon strap is often processed with a large amount of plasticizer to impart flexibility and strength to the strap the cost of the strap is drastically high, thereby increasing the overall cost of the timepiece. The tear resistance of the silicon straps also often tends to reduce over regular use, and the existing silicon straps usually last only for a time period of about two years. The silicon straps are also non-biodegradable and hence, are not suitable for easy disposal as well. Similarly, the existing TPU straps also do not fulfill all the criteria critical for a good watch strap in accordance with the GHS, thereby making them also less suitable as choices for an ideal strap.

The present disclosure is directed to overcome one or more limitations stated above.

The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgment or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

SUMMARY OF THE DISCLOSURE

One or more shortcomings of conventional straps are overcome, and additional advantages are provided through the composition and the method as claimed in the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In a non-limiting embodiment of the present disclosure, a composition for a polymeric strap of a timepiece is described. The composition comprises a polymer at a concentration ranging from about 96.5 vol% to about 97.6 vol% of a total volume of the composition. A first additive is mixed with the polymer at a concentration ranging from about 1 vol% to about 1.4 vol% of the total volume of the composition. The composition further includes a second additive mixed with the polymer at a concentration ranging from about 1.4 vol% to about 1.8 vol% of the total volume composition. The first additive, the second additive and the polymer are blended to form a mixture, and the mixture is injection moulded to produce the polymeric strap of the timepiece.

In an embodiment of the present disclosure, the polymer is a thermoplastic polyurethane (TPU) polymer. The first additive includes benzophenone. The second additive includes organo-phosphite antioxidant.

In an embodiment of the present disclosure, the mixture comprising the first additive, the second additive and the polymer is dried for a time ranging from about 100 minutes to about 140 minutes at a drying temperature ranging from about 65 °C to 85 °C before subjecting to injection mold for producing the polymeric strap.

In an embodiment of the present disclosure, the composition comprises a coloring agent.

In another non-limiting embodiment of the present disclosure, a method for producing a polymeric strap for a timepiece is described. The method includes mixing a polymer, a first additive and a second additive to form a mixture. Concentration of the polymer ranges from about 96.5 vol% to about 97.6 vol% of a total volume of composition. Concentration of the first additive ranges from about 1 vol% to about 1.4 vol% of the total volume of the composition. Concentration of the second additive ranges from about 1.4 vol% to about 1.8 vol% of the total volume of the composition. The method further includes drying the mixture for a pre-defined time at a pre-determined temperature and injection moulding the mixture to produce the polymeric strap.

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings. One or more embodiments are now described, by way of example only, with reference to the accompanying drawings wherein like reference numerals represent like elements and in which:

Fig. 1 is a flowchart illustrating the method of manufacturing the strap, in accordance with an embodiment of the present disclosure.

The figure depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which forms the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that, the conception and specific embodiments disclosed may be readily utilized as a basis for modifying other devices, systems, assemblies, and mechanisms for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that, such equivalent constructions do not depart from the scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristics of the disclosure, to its system, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

In accordance with various embodiments of the present disclosure, a composition for a polymeric strap for a timepiece is described. The polymeric strap of the timepiece made from the composition which will be described in forthcoming paragraphs is a cost-effective production alternative to the silicon straps. The polymeric strap the above-mentioned composition has high tear resistance. The composition for the polymeric strap includes a polymer at a concentration ranging from about 96.5 vol% to about 97.6 vol% of a total volume composition. The polymer is mixed with a first additive and a second additive. Concentration of the first additive ranges from about 1 vol% to about 1.4 vol% of the total volume of the composition. Concentration of the second additive ranges from ranging from about 1.4 vol% to about 1.8 vol% of the total volume of the composition. The first additive, the second additive and the polymer are blended to form a mixture and the mixture is injection moulded to produce the polymeric strap of the timepiece.

The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a composition, method that comprises a list of elements or steps does not include only those elements or steps but may include other elements not expressly listed or inherent to such composition or method. In other words, one or more elements in a composition “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the composition or the product.

Present disclosure discloses a wrist-worn article that may be configured to be strapped or secured to an arm of a wearer with a securing structure. The securing structure of the wrist-worn article among other components include one or more straps used to secure the wrist worn article to the arm of the wearer. The securing structure hereinafter may be referred to as “strap”. The wrist-worn article may be one or any combination of one or any combination of one or more mechanical device, electronic devices, electromechanical devices, or one or more ornamental articles designed to be worn by a wearer on his or her arm. According to the present disclosure, the wrist-worn article may be a timepiece but not limiting to the same. The strap of the present disclosure may be made of a polymeric material. Hereinafter, the strap may be referred to as a polymeric strap and may be alternatively used. The polymeric strap may be made of a composition which will be elucidated in the forthcoming paragraphs. The composition for the polymeric strap of the present disclosure comprises a polymer along with at least two additives, wherein the additives are selected from but not limited to benzophenone and organo-phosphite antioxidant. The polymer used may be a thermoplastic polyurethane (TPU) polymer but not limiting to the same. Accordingly, said composition comprises polymer along with benzophenone and organo-phosphite antioxidant. As a person skilled in the art will realize, purely for the ease of reference, within the present disclosure, the said benzophenone is referred to as the first additive and the said organo-phosphite antioxidant is referred to as the second additive. However, this nomenclature does not determine or indicate the order of preference of the additives or the order, preference, or sequences of their inclusion in the mixture of the present disclosure.

In some embodiments, the first additive is mixed with the polymer at a concentration ranging from about 1 % to 1.4% and is preferably at 1.2 % of the total volume.

In some embodiments, the second additive is mixed with the polymer at a concentration ranging from about 1.4 % % to 1.8% and is preferably at 1.5% of the total volume. In some embodiments, the coloring agent is added in traces to impart color to the polymeric strap. Accordingly, this mixture of the polymer with the first additive, the second additive and the coloring agent is subjected to injection moulding at pre-determined set of operational parameters for obtaining the thermoplastic polyurethane polymer composition in the form of a strap.

In an embodiment, the ratio of the mixture subjected to injection moulding including the polymer, the first additive and the second additive is 97.3:1.2:1.5. Accordingly, in some embodiments, the polymer, the first additive and the second additive are mixed together in the ratio of about 97.3:1.2:1.5, or the first additive is present at a concentration ranging from about 1 % to 1.4%, preferably at 1.2 % of the total volume, and the second additive is present a concentration ranging from about 1.4 % to 1.8%, preferably at 1.5 % of the total volume. Thus, in an exemplary embodiment, for a polymeric strap of said composition comprising about 1000g of the polymer, the first additive ranges from about 12 grams to 14 grams and the second additive ranges from about 15 grams to 18 grams.

Properties of the polymeric strap include improved flexibility, soft to the touch, 100% resistance to UV bacterial fungi, safe permissible continuous usage on skin for a time period of at least three years and enhanced tear resistance. The above-mentioned thermoplastic polyurethane polymer may also be resistant to chemicals, lipids, cleaning agents and bacteria. The coloring agents may be added to suitably obtain a transparent thermoplastic polyurethane polymer. The polymeric strap meets biocompatibility test requirements for ISO 10993-1 including biological evaluation of healthcare devices. In an embodiment, hydrographic prints may also be applied to the straps improve the aesthetics of the polymeric straps.

In an embodiment, the polymeric straps of the present disclosure costs 40% less compared to conventional silicon straps. Further, the polymeric straps of the present disclosure may be manufactured by continuous process where yield rate is high compared to the conventional silicon straps where, the silicon straps are manufactured by batch process with lesser yield rate. The yield rate of conventional silicon straps is about 50% lesser than polymeric straps of the present disclosure. The secondary operations on the straps of the present disclosure are less than 5% whereas, the secondary operations on conventional silicon straps is around 60% which increases the overall cost of the strap.

While the components or the constituents of the polymer composition are important for achieving the desired properties of the end product, i.e., the timepiece strap, the manner in which the components or the constituents are included and subjected to injection moulding also play an important role. Thus, the present disclosure also relates to a method of manufacturing of the polymer composition of the present disclosure, in a desired form, including but not limiting to the form of a timepiece strap.

The following paragraphs further describe the present disclosure with reference to figure 1, which elaborates on the said method of manufacturing.

Fig. 1 is a flowchart illustrating the method of manufacturing of the composition of the present disclosure in the form of a timepiece strap. The first step 101 illustrates mixing of the polymer with the plurality of additives i.e., the first additive, the second additive and the coloring agent to form a mixture. As mentioned above, the first additive is mixed with the polymer at a concentration ranging from about 1 % to 1.4%, preferably at about 1.2 %. Further, the second additive is mixed with the polymer at a concentration ranging from about 1.4 % to 1.8%, preferably at 1.5%. The coloring agent is also optionally added to the composition in trace amounts and belended along with the first and second additive and the polymer to impart the color to the strap.

Further, the second step 102 illustrates drying of the above-mentioned mixture of polymer, for a pre-defined drying time at a pre-determined temperature before being injection molded to obtain the composition in the form of the strap. Molding materials generally absorb moisture from the atmosphere to a certain extent. Therefore, it is necessary to dry the material and remove the moisture before subjecting to injection moulding. The material is dried in a drying apparatus for removing the moisture. The pre-defined drying time ranges from about 100 minutes to 140 minutes and is preferably about 120 minutes. Further, the pre-determined drying temperature ranges from about 65 °C to 85 °C and is preferably about 75 °C.

The third step 103 illustrates the step of injection moulding of the above-mentioned mixture to obtain the polymeric strap of said composition of the present disclosure. The mould is in the shape of the required polymeric strap. The above-mentioned mixture is initially fed into the mould of an injection moulding apparatus. In an embodiment, the injection moulding apparatus uses a screw-type plunger to force the mixture of polymer material into a mould cavity. The composition reaches a molten state as the composition traverses though the plunger. Further, the molten polymer deposited inside the mould cavity solidifies into a shape that has conformed to the contour of the mould. Injection moulding consists of the high-pressure injection of the raw material into a mould, which shapes the composition into the desired form. Further, the moulds are of a single cavity or multiple cavities for mass production.

In some embodiments, while the present disclosure exemplifies the method of manufacturing the polymeric strap of said composition herein, it will be readily understood by a person skilled in the art that all possible and reasonable changes and variations within the ambit of common knowledge and routine experimentation are within the purview of the present disclosure, as long as they provide same or similar end results. For example, when the two additives are mixed with the polymer to prepare the mixture, either all three – the polymer, and the two additives can be mixed together in one step, simultaneously or sequentially, or in multiple steps, such as by mixing part of the polymer with the first additive, separately mixing part of the polymer with the second additive, and then combining the two mixtures to form the final mixture.

In some embodiments, the above-mentioned mixture is initially plasticized by a screw-type plunger. The mixture is converted to a molten state due to high pressure and temperature inside the screw type plunger. The molten mixture is further injected into the mould for shaping the mixture to the polymeric strap.

In some embodiments, the screw of the plunger rotates at a speed ranging from about 90 rpm to 100 rpm with a back pressure ranging from about 90kg/cm2to 100kg/cm2.

In some embodiments, the pressure and temperature exerted on the molten mixture inside the screw type plunger ranges from 15 mm to 35 mm and 2 sec to 5 sec, respectively.

In some embodiments, the plasticized or the molten mixture is injected into the mould at the speed ranging from about 14mm/s to 16mm/s and the pressure ranging from about 22kg/cm2 to 30kg/cm2.

In some embodiments, the total injection time for the molten mixture to be injected from the screw type plunger to the mould is about 4 seconds.

In exemplary embodiments, the below table 1 and table 2 indicate the various operational parameters during plasticization of the mixture and the injection of the molten mixture into the mould.

Plasticization Dec Stages Dec
1 2 3
Rotation Speed in rpm 10 120 120 6
Back Pressure kg/cm2 10 110 140 10
Speed in rpm
Pressure kg/cm2 110 140
Position in mm 0 25 70 8

Table 1: Operational parameters of the screw type plunger during plasticization of the polymer.

Injection Hold Stages
Injection Stages Speed mm/s 10 10
Speed mm/s 14 15 16 Pressure kg/cm2 15 45
Pressure Kg/cm2 22 25 30 Time Sec 2 5
Position mm 15 25 35
Enable Injection Time in sec 4

Table 2: Operational parameters of the screw type plunger during injection of the polymer into the mould.

With reference to the Table 1, the rotational speed of the screw in the screw type plunger is controlled in a plurality of stages. The rotational speed may be initially set at 10 rpm and the speed may gradually be increased to 120 rpm over two stages. Further, the back pressure after plasticization of the polymer in the plunger may also be controlled in a plurality of stages as mentioned in the Table 1. The rotational speed of the screw is controlled in plurality of stages so that the resin or the mixture inside the plunger is plasticized to the required extent. Increasing the rotation of the screw causes the polymer to not plasticize to the required extent and reducing the rotation of screw causes the polymer to over plasticize. Therefore, the screw type plunger may be operated at two different stages and at 120 rpm so that the polymer is plasticized to the required extent. The back pressure may also be set such that the plasticized polymer is molded consistently into the strap.

The quality of the straps is influenced by the parameters including but not limited to injection speed, injection pressure, injection time etc. as disclosed in the Table 2. Further, if the temperature of the plasticized polymer is too low or too high, the polymer in the mould may be of a completely molten state or may be subjected to thermal degradation as the polymer is injected into the mould. Also, low injection pressure causes the straps to develop cracks and the straps manufactured through low injection pressure are often defective. Setting the injection speed and injection pressure as disclosed in Table 2, reduces internal stresses in the straps and ensures an improved quality of the straps.

In some embodiments, after the molten mixture is injected into the mould, the mould is closed and is held in the closed condition for a time period ranging from about 2 sec to 5 sec.

In some embodiments, a pressure ranging from about 15kg/cm2 to 45kg/cm2 is exerted onto the molten mixture inside the mould cavity when the mould is in the closed condition.

The below table 3, indicates the various operational parameters the polymer is subjected during the closed condition of the mould.

Mould close Stages Mould protection Mould locking
Speed % 25 30 20 30 50
Pressure kg/cm2 25 20 20 30 140
position mm 130 90 2.8 2.8 0.02

Table 3: Operational parameters of the mould in the closed condition.

In some embodiments, the mould is held in the closed condition until the required shape of the mould is imparted to the molten mixture. The final polymer composition takes the shape of the mould and required strap is thus manufactured in the above-mentioned manner.

In some embodiments, the mould is designed such that a weld line on top surface of the strap is avoided and consequent accumulation of hairline stress in the strap is also avoided.

In an embodiment of the disclosure, the above-mentioned composition of the polymeric strap and the method of manufacturing the strap offers a cost-effective production alternative to the silicon straps.

In an embodiment of the disclosure, the polymeric strap with the above-mentioned composition has a hardness of 85 A.

In an embodiment of the disclosure, the polymeric strap with the above-mentioned composition has high tear resistance.

EQUIVALENTS

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
It will be understood by those within the art that, in general, terms used herein, are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding the description may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."
While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated in the description.

Referral numerals:

Description Referral numerals
Mixing a thermoplastic polyurethane polymer with the plurality of additives and the coloring agent. 101
Drying the mixture for a pre-determined drying time at a pre-determined temperature. 102
Injection moulding the mixture to obtain the polymer composition. 103

Numerical ranges stated in the form ‘from x to y’ include the values mentioned and those values that lie within the range of the respective measurement accuracy as known to the skilled person. If several preferred numerical ranges are stated in this form, of course, all the ranges formed by a combination of the different end points are also included. The term ‘about’ preceding numerical values envisages a margin of error of ±10%.
It is to be noted that the term ‘a’ or ‘an’ entity refers to one or more of that entity. As such, the terms ‘a’ (or ‘an’), ‘one or more’, and ‘at least one’ can be used interchangeably herein.
As regards the embodiments characterized in this specification, it is intended that each embodiment be read independently as well as in combination with another embodiment. For example, in case of an embodiment 1 reciting 3 alternatives A, B and C, an embodiment 2 reciting 3 alternatives D, E and F and an embodiment 3 reciting 3 alternatives G, H and I, it is to be understood that the specification unambiguously discloses embodiments corresponding to combinations A, D, G; A, D, H; A, D, I; A, E, G; A, E, H; A, E, I; A, F, G; A, F, H; A, F, I; B, D, G; B, D, H; B, D, I; B, E, G; B, E, H; B, E, I; B, F, G; B, F, H; B, F, I; C, D, G; C, D, H; C, D, I; C, E, G; C, E, H; C, E, I; C, F, G; C, F, H; C, F, I, unless specifically mentioned otherwise.

,CLAIMS:We claim:

1. A composition for a polymeric strap of a timepiece, the composition comprising:
a polymer at a concentration ranging from about 96.5 vol% to about 97.6 vol% of a total volume of the composition;
a first additive mixed with the polymer at a concentration ranging from about 1 vol% to about 1.4 vol% of the total volume of the composition; and
a second additive mixed with the polymer at a concentration ranging from about 1.4 vol% to about 1.8 vol% of the total volume of the composition,
wherein, the first additive, the second additive and the polymer are blended to form a mixture, and the mixture is injection molded to produce the polymeric strap of the timepiece.

2. The composition as claimed in claim 1, wherein the polymer is a thermoplastic polyurethane (TPU) polymer.

3. The composition as claimed in claim 1, wherein the first additive including benzophenone.

4. The composition as claimed in claim 1, wherein the second additive including organo-phosphite antioxidant.

5. The composition as claimed in claim 1, wherein the mixture comprising the first additive, the second additive and the polymer is dried for a pre-defined time ranging from about 100 minutes to 140 minutes at a pre-determined drying temperature ranging from about 65 °C to 85 °C before subjecting to injection mold for producing the polymeric strap.

6. The composition as claimed in claim 1 comprises traces of coloring agent.

7. A timepiece comprising a polymeric strap of a composition as claimed in claim 1.

8. A method for producing a polymeric strap for a timepiece, the method comprising:
mixing a polymer, a first additive and a second additive to form a mixture, wherein concentration of the polymer ranges from about 96.5 vol% to about 97.6 vol% of a total volume of the composition, concentration of the first additive ranges from about 1 vol% to about 1.4 vol% of the total volume of the composition, and concentration of the second additive ranges from about 1.4 vol% to 1.8 vol% of the total volume of the composition;
drying the mixture for a pre-defined time at a pre-determined temperature; and
injection moulding the mixture to produce the polymeric strap.

9. The method as claimed in claim 8, wherein the predefined time ranges from about 100 minutes to about 140 minutes, preferably 120 minutes.

10. The method as claimed in claim 8, wherein the pre-determined temperature ranges from about 65 °C to 85 °C, preferably 75°C