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US-12624244-B2 - Part of a cosmetic article decorated with a resin, and method for covering this part with the resin

US12624244B2US 12624244 B2US12624244 B2US 12624244B2US-12624244-B2

Abstract

The invention provides a part decorated with a polyurethane resin mainly comprising two components. The first component consists of a polyol and the second component consists of isocyanate, the isocyanate-to-polyol weight ratio being comprised between 100:100 and 100:40.

Inventors

  • Pierre Dumont
  • Frederic Leleu
  • Pierre-Yves Gilet

Assignees

  • SILGAN DISPENSING SYSTEMS LE TREPORT S.A.S.

Dates

Publication Date
20260512
Application Date
20211209
Priority Date
20201223

Claims (7)

  1. 1 . A push button for a cosmetic item comprising a surface area delineated by a bend, the surface area and bend being suitable for containing a flowable decorative polyurethane resin, said surface area being coated with a decorative polyurethane resin comprising: a polyol; and an isocyanate; wherein the isocyanate-to-polyol weight ratio is between 100:57 and 100:67 wherein the viscosity of the decorative polyurethane resin is between 400 and 600 mPa's at an ambient temperature of around 25° C., when the resin is applied to a part to be decorated, wherein the resulting hardness of the decorative polyurethane resin is at least 80 Shore D, wherein the decorative polyurethane resin when hardened comprises an outer surface with a rounded, dome-shaped appearance having an apex, and wherein the decorative polyurethane resin has a smooth, glossy domed surface with an aesthetic appearance akin to that of enamel when hardened.
  2. 2 . The push button of claim 1 , wherein the isocyanate-to-polyol weight ratio is 100:62.
  3. 3 . The push button of claim 1 , wherein the decorative polyurethane resin further comprises at least one colorant.
  4. 4 . The push button of claim 1 , wherein said area comprises a surface delineated by a rim.
  5. 5 . The push button of claim 4 , wherein the decorative polyurethane resin coating said area comprises an outer surface with a dome having an apex overtopping said rim.
  6. 6 . The push-button of claim 1 , wherein the surface area of the part is inclusively between 70 mm 2 to 300 mm 2 and is coated with an amount of resin calibrated inclusively between 0.05 g and 0.2 g.
  7. 7 . The push-button of claim 1 , wherein 0.1 g of resin is deposited in the area forming a 0.9 mm overtopping dome.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a national stage application of International Patent Application Number PCT/EP2021/085103, filed 9 Dec. 2021, which claims priority to French Patent Application Number FR2014041, filed 23 Dec. 2020, the disclosures of which are hereby incorporated by reference in their entireties. TECHNICAL FIELD OF THE INVENTION The invention relates to a part decorated with a resin, for example parts for cosmetic items, such as push buttons for product dispensers or tubes for lipstick. This resin has an aesthetic appearance akin to that of enamel. The invention relates to a method of manufacturing this resin and coating this part with the decorative resin. TECHNICAL BACKGROUND Fashion jewelry, key rings, interior decorations, etc., have all been designed with enamel, providing a distinctive aesthetic effect. Enamel is produced at high temperatures, in the range of several hundred degrees. Plastic parts therefore cannot be used in this enamel production method, as plastic parts would warp and be unable to withstand such high heat. This is particularly true of plastic parts for cosmetics items. These can be push buttons on a device for dispensing fluid products. They can also be caps for lipstick tubes. There are many plastic and/or metal parts to which it would be aesthetically desirable to give an enamel-like appearance. With regard to push buttons, it is preferable to have an upper pressure-bearing surface made of resin, with a slightly domed shape. The purpose of this invention is to provide a resin that can be used to decorate plastic parts and which has an enamel-like appearance. This resin must be chosen so as to obtain: a resin dome overtopping the push button at an adequate height;a suitable hardness (measured in Shore D), i.e., resistant to scratches, for example from a user's fingernail;a viscosity that is ideal for coating a deposition area provided on the plastic part, therefore sufficiently fluid but also sufficiently viscous so as not to overflow the area;consistency in the color to be obtained;good abrasion resistance;a glossy surface with no bubbles. The part to be decorated must have a suitable area for containing the resin. The parameters for depositing the resin on the part must also be correctly defined in order to obtain a convincing final result akin to that of enamel in terms of decorative effect. Indeed, the goal is to obtain a smooth, glossy, domed, surface with no bubbles. SUMMARY OF THE INVENTION This goal is achieved by means of a part for a cosmetic item, which has an area coated with a decorative polyurethane resin mainly comprising two components. This part is characterized primarily in that the first component of the resin consists of a polyol and the second component of the resin consists of isocyanate, the isocyanate-to-polyol weight ratio being comprised between 100:100 and 100:40. The main idea of this invention consists of designing a part decorated with a polyurethane resin obtained from a mixture of two components: polyol and isocyanate. The base element is polyol, which has viscosity characteristics that enable it to be applied and spread on flat surfaces, provides a good aesthetic finish in terms of gloss, and is used to apply clear coats, for example. The “base element” is the element offering the right aesthetic result, to which a “hardener” must be added, regardless of the respective amounts of the two products. Isocyanate is a hardener, which is required in the formulation to achieve a three-dimensional (3D) shape such as a dome. It also makes it possible to obtain a final resin with a certain hardness and therefore scratch-resistant. The ratio between the amount of polyol and the amount of isocyanate makes it possible to obtain a final formulation that meets all of the above criteria, namely hardness, viscosity, surface finish, color consistency, abrasion resistance and 3D formability. According to the various embodiments of the invention, which can be taken together or separately: the isocyanate-to-polyol weight ratio is comprised between 100:57 and 100:67.the isocyanate-to-polyol weight ratio is preferably 100:62.the viscosity of the resin is between 400 and 600 mPa·s at an ambient temperature of around 25° C., when the resin is applied to a part to be decorated.the resin also comprises one or more colorant(s). This part can be, for example, a push button or a cap for a lipstick tube. Said area has a surface to be decorated delineated by a change in shape such as a rim, groove or bend. According to a first possible configuration, the resin coating said area has an outer surface with a rounded, dome-shaped appearance. For example, if the surface to be decorated is delineated by a rim, the apex of the dome will overtop the rim. According to a second possible configuration, the resin coating said area has an outer surface with a flat appearance. It can be located flush with the rim, or under the rim, for example.