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US-12623394-B2 - Preform and container with variable transmittances

US12623394B2US 12623394 B2US12623394 B2US 12623394B2US-12623394-B2

Abstract

The invention relates to a preform intended for forming containers by blow molding or stretch-blow molding, the preform being made of plastic material including at least one additive giving the plastic material the property of at least partially filtering the visible light spectrum, the preform comprising a wall forming a hollow body, said one or more additive(s) giving the plastic material the property of at least partially allowing the passage of light in the infrared spectrum.

Inventors

  • Guy Feuilloley
  • Naïma Boutroy

Assignees

  • SIDEL PARTICIPATIONS

Dates

Publication Date
20260512
Application Date
20210422
Priority Date
20200422

Claims (20)

  1. 1 . An opaque preform intended for forming containers by blow molding or stretch-blow molding, the preform comprising: a hollow body being made of a plastic material including at least one additive giving the plastic material the property of at least partially filtering the visible light spectrum, the hollow body comprising a wall comprising a thickness of about 1 mm to about 5 mm that is between about 4-50 times greater than a thickness of a wall of the container that is formed from the preform, characterized in that said one or more additive(s) give the plastic material the property of at least partially allowing the passage of light in the infrared spectrum, and in that the preform wall has, under electromagnetic radiation emitted perpendicular to the preform wall, transmittance in the visible spectrum, that is substantially equal to 0% in the wavelength range of 350 nm to 520 nm; and transmittance in the infrared spectrum within a transmittance range extending between a threshold transmittance and an upper transmittance, for at least one wavelength within the range of 700 nm to 2250 nm, the threshold transmittance being equal to 5% and the upper transmittance being equal to 70%.
  2. 2 . The preform as claimed in claim 1 , wherein the transmittance in the infrared spectrum is within the transmittance range for a wavelength of 1130 nm.
  3. 3 . The preform as claimed in claim 1 , wherein the threshold transmittance equals 8%.
  4. 4 . The preform as claimed in claim 1 , wherein the upper transmittance equals 50%.
  5. 5 . The preform as claimed in claim 1 , wherein the plastic material also comprises at least one colorant.
  6. 6 . The preform as claimed in claim 1 , wherein the thickness of the wall of the hollow body is within the range of 1 mm to 2 mm.
  7. 7 . The preform as claimed in claim 1 , wherein the plastic material comprises one or more additives forming a barrier against radiation below 350 nm.
  8. 8 . The preform as claimed in claim 1 , wherein the transmittance in the infrared spectrum is within the transmittance range at wavelengths within the range of 950 nm to 1400 nm.
  9. 9 . The preform as claimed in claim 1 , wherein the threshold transmittance equals 10%.
  10. 10 . The preform as claimed in claim 1 , wherein the upper transmittance equals 20%.
  11. 11 . The preform as claimed in claim 1 , wherein the transmittance in the infrared spectrum is within the transmittance range at wavelengths within the range of 750 nm to 1400 nm.
  12. 12 . The preform as claimed in claim 11 , wherein the transmittance in the infrared spectrum is within the transmittance range for a wavelength of 1130 nm.
  13. 13 . The preform as claimed in claim 11 , wherein the threshold transmittance equals 8%.
  14. 14 . The preform as claimed in claim 11 , wherein the upper transmittance equals 50%.
  15. 15 . The preform as claimed in claim 1 , wherein the transmittance in the infrared spectrum is within the transmittance range for one wavelength or within a spectrum of wavelengths within one of the following ranges: 1110-1160 nm; 1390-1450 nm; 1610-1650 nm; 1675-1700 nm; 1880-2100 nm; and 2170-2230 nm.
  16. 16 . The preform as claimed in claim 15 , wherein the transmittance in the infrared spectrum is within the transmittance range for a wavelength of 1130 nm.
  17. 17 . The preform as claimed in claim 15 , wherein the threshold transmittance equals 8%.
  18. 18 . The preform as claimed in claim 15 , wherein the upper transmittance equals 50%.
  19. 19 . The preform as claimed in claim 1 , wherein the transmittance measured on a wall of the container for which said preform is intended is less than 5% within the wavelength range of 350 nm to 520 nm, whereby the transmittance of the wall of the preform in the visible spectrum is considered to be substantially equal to 0%.
  20. 20 . The preform as claimed in claim 19 , wherein the transmittance measured on a wall of said container is less than 0.5%, within the wavelength range of 350 nm to 520 nm.

Description

FIELD OF INVENTION The field of the invention is that of the design and the manufacture of plastic containers. More specifically, the invention relates to the manufacture of containers intended to contain products that must be protected from light and that are manufactured by blow molding or stretch-blow molding a preform. BACKGROUND Conventionally, a preform comprises a hollow body, generally rotationally cylindrical, a neck that has a lip, and a base that closes the body opposite the neck. In order to produce a preform, a plastic material forming the preform is injected into an injection mold in the fluid state and at a high pressure. A conventional technique for manufacturing a container from a preform involves heating the preform inside an oven, then forming the container in a blowing mold, which will simply be called “mold”. Forming the container involves introducing the heated preform into the mold, which has a wall defining a cavity with the impression of the container, and in injecting a fluid into the preform, via a pipe, which fluid is a fluid such as a pressurized gas or a liquid for pressing the material of the preform against the wall of the mold. In order to correctly heat the preforms, they need to be heated within a process temperature range that is greater than the glass transition temperature of the material (approximately 70 degrees Celsius in the case of PET), yet nevertheless that is less than the spherulitic crystallization temperature of this material and much less than the melting temperature. In the industry, ovens are conventionally used that are equipped with halogen lamps, which are particularly powerful and radiate over the entire light spectrum. This type of oven has low efficiency with respect to the power output compared to the actual heating of the preform. Indeed, a material such as PET is particularly insulating, and variably absorbs electromagnetic radiation emitted in the infrared spectrum. Furthermore, a preform can have a wall that can be up to 5 mm thick. Consequently, following a given heating operation, a temperature difference can be observed between the outer skin and the inner skin of the wall of the body of the preform. This temperature difference is compensated by the presence of forced ventilation in the ovens. This ventilation allows the outer skin to be cooled in order to prevent it from reaching the spherulitic crystallization temperature, whereas the heat is diffused in the thickness of the wall of the body of the preform. Ovens also exist that are equipped with laser diodes. This technology aims to improve the output of the ovens, whilst allowing the time for heating a preform to be reduced. The laser heating technique is particularly described in the international application published under number WO 2006/056673, and an improvement of this technique is described in the European patent published under number EP 2125316. Within a unit for manufacturing containers, and based on basic preforms, for example, which are intended to be used to form transparent containers intended to contain water, it is possible to obtain production rates of 2500 to 2700 bottles per hour and per mold. Depending on the destination of the containers, said containers must have precise features that can be obtained by virtue of the design of the preforms. More specifically, some products contained in containers can be altered under the effect of light. This is particularly the case for milk, the taste of which changes under the effect of light. This altered taste develops into two sensations: an “activated” taste (cabbage taste, cooked taste or mushroom taste) that occurs very quickly;an oxidation taste (taste of cardboard, paper, metal, oil) that develops more slowly. With respect to milk, it is particularly known that light, within the wavelength range of 350 nm to 520 nm, causes riboflavin degradation, which is one of the causes of the “activated” taste. In order to allow milk to be preserved in plastic containers, for a relatively long duration and whilst avoiding the alteration described above, plastic containers are conventionally used that have the ability of preventing light from passing through the wall thereof. These containers, which are often white, are obtained from preforms made of plastic material including one or more additives intended to create this “light barrier” capability. According to a well known example, for milk products, bottles are produced from preforms made of PET resin with added titanium dioxide (TiO2). The titanium dioxide provides the white color and the light barrier functionality in the visible spectrum and allows the riboflavin (vitamin B2) degradation to be prevented. For other applications of bottles, titanium dioxide is also added to obtain visual, non-functional opacity. This type of additive nevertheless has a negative impact on the actual manufacture of the containers. Indeed, these additives, in addition to having a “light barrier” effect