Description:FIELD OF INVENTION:
[001] The present invention relates to plastic containers, and more particularly, relates to a method of producing containers having reinforcing pattern at inner walls.

BACKGROUND & PRIOR ART:
[002] Plastic containers are widely used for number of commercial purposes. The containers may be in the form of cylindrical bottles for storage of liquid. In most of the uses, the strength of the container is critical. Smart selection of material of construction takes care of the strength factor. However, to provide further strength to the container, reinforcing ribs are structurally included around the body of the container. Most typically, such reinforcing ribs are included at the outer surface of the body of the container. However with this, the outer surface becomes uneven, and not so adaptable for labeling and/or decoration purpose.
[003] To overcome said issue, some selected producers started the practice of incorporating the reinforcing ribs at an inner surface of the container. The current applicant has demonstrated such container in IN396968, wherein the container is prepared by the injection blow molding method.
[004] The present specification pertains to the container with the reinforcing ribs by different method, yet rendering similar advantages.

SUMMARY OF INVENTION:
[005] It is a main object of the invention to produce a plastic container having greater compression strength at the same weight, or preferably at lower weight at the equivalent compression strength /performance.
[006] It is another object of the invention to produce the plastic containers having reinforcing ribs on its inner wall.
[007] Accordingly, the present invention discloses a method of producing a container with reinforcing pattern on its inner wall.
[008] In an embodiment, the said method is initiated with injecting at least one layer of molten thermoplastic material into an injection mold to form a preform inside the injection mold, wherein the preform is provided with patterned grooves at its inner side. The said preform is subsequently cooled, and ejected from the injection mold. The preform is then reheated to a predetermined termperature and stretched axially by a stretch rod. The stretched preform is blown with a compressed air to stretch tangentially and form a container, and finally ejected as a final product, wherein the container has reinforcing pattern on its inner wall that corresponds to patterned grooves on the preform.
[009] In an embodiment, the patterned grooves on the preform are effected by inscribing the patterned indentations onto a core rod in the injection mold. The said patterned grooves may be selected from longitudinal grooves, circumferential grooves, a combination of longitudinal & circumferential grooves, or any other pattern.
[010] The axial stretching of the reheated preform is performed by inserting a stretch rod, whereas the tangential stretching is performed by blowing air into the reheated preform.
[011] In an embodiment where the container has longitudinal reinforcing ribs on its inner wall, the longitudinal indentations on the core rod are present in range of 4 to 64 and spaced apart in range of 0.5 mm to 10 mm. The longitudinal indentations have depth of 0.1 mm to 10 mm.
[012] In an embodiment where the container has circumferential ribs on its inner wall, the circumferential indentations on the core rod are present in range of 4 to 120 spaced apart in range of 0.5 mm to 50 mm and have depth of 0.1 mm to 10 mm.
[013] The present invention further discloses an apparatus for producing containers having reinforcing patterned ribs on the inner wall.
[014] The said apparatus comprises an injection mold unit for injecting at least one layer of molten thermoplastic material and forming a preform; a reheating unit for reheating the preform; a stretching unit for axial stretching of the reheated preform; and a blowing unit for blowing compressed air for tangential stretching and to form the container as a final product.
[015] The injection mold unit comprises of an injection unit and a preform mold. The preform mold includes a core rod inscribed with patterned indentations due to which grooved preform may be prepared. Such patterned indentations may include longitudinal indentations, circumferential indentations, a combination of longitudinal & circumferential indentations, or any such pattern.
[016] The container so formed with the method and the apparatus, as described above, has reinforcing pattern at its inner wall, the said pattern corresponding to the pattern on the core rod as well as the preform. Importantly, the container is made of a thermoplastic material, which is selected from High Density Poly Ethylene (HDPE), Polypropylene (PP), their blends, Poly Ethylene Terrephthalate (PET), PCR and such. Such container with reinforcing pattern on the inner wall exhibits greater compression and hoop strengths.
[017] In an another embodiment, the container will have isogrid structured pattern on its inner wall, correspsonding to an isogrid structure on the core rod.

BRIED DESCRIPTION OF DRAWINGS:
[018] Following figures show the container as well as the apparatus disclosed in the present invention:
Figure 1(a) shows a container with pattern consisting of longitudinal reinforcing ribs on the inner wall.
Figure 1(b) shows the container with pattern consisting of circumferential reinforcing ribs
Figure 1(c) illustrates the container with a pattern consisting of longitudinal & circumferential ribs.
Figure 2(a) shows the core rod inscribed with the pattern consisting of longitudinal indentations.
Figure 2(b) illustrates the core rod inscribed with the pattern consisting of circumferential indentations.
Figure 2(c) illustrates the core rod inscribed with the pattern consisting of combination of longitudinal & circumferential indentations.
Figure 2(d) illustrates the core rod inscribed with the iso grid pattern

DETAILED DESCRIPTION OF INVENTION:
[019] In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention.
[020] Reference herein to “one embodiment” or “another embodiment” means that a particular feature, structure, or characteristics described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in a specification are not necessarily all referring to the same embodiment, unless otherwise stated, nor are separate or alternative embodiments, mutually exclusive of other embodiments.
[021] As used herein, the term “plurality? refers to the presence of more than one of the referenced items, and the terms “a”, “an”, and “at least” do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.
[022] The present invention will now be described in detail with reference to optional and preferred embodiments so that various aspects of the invention will be more clearly understood, however, should not be construed to limit the scope of the invention.
[023] The embodiments of the present invention may be comprehended by referring to the figures appended to the end of the specification. It may be noted that the figures are provided for the purpose of illustrating the preferred as well as alternate embodiments, if any, of the present invention. It may further be noted that the figures do not restrict the scope of the invention. Any variations from the figures by the person skilled in the art may still be falling under the scope if the invention.
[024] Accordingly, the present invention discloses a method of producing a container with reinforcing patterns on its inner wall. As stated in the Background, the presence of reinforcing ribs on the inner wall results in smooth outer surface which is particularly advantageous for labeling as well as aesthetic purposes, alongwith other advantages.
[025] The said method comprises of: injecting at least one layer of molten thermoplastic material into an injection mold to form a preform inside the injection mold, wherein the preform is provided with a patterned grooves on an inner side; ejecting the said preform from the injection mold; subsequently cooling the preform; reheating the preform at a predetermined temperature; stretching the reheated preform axially with a stretch rod; blowing a compressed air into the stretched preform stretching it tangentially; and ejecting the container as a final product, wherein inner walls of the container has reinforcing pattern.
[026] The patterned grooves on the preform are effected by inscribing the patterned indentations onto a core rod in the injection mold. The said patterned grooves may be selected from longitudinal grooves, circumferential grooves, a combination of longitudinal & circumferential grooves, or any other pattern.
[027] The axial stretching of the reheated preform is performed by inserting a stretch rod, whereas the tangential stretching is performed by blowing air into the reheated preform.
[028] The said method is described herein in detail: The thermoplastic material is heated at a predetermined temperature to form molten thermoplastics. The molten thermoplastics are injected into the injection mold unit. The said thermoplastics are selected from High Density Poly Ethylene (HDPE), Polypropylene (PP), or blends, Poly Ethylene Terephthalate (PET), PCR thereof.
[029] In a preferred embodiment, the thermoplastic material may be Poly Ethylene Terephthalte (PET) and or Recycled Poly Ethylene Terephtahlate (rPET). In an alternate embodiment, which may not be a secondary embodiment, the thermoplastic material is a combination of Poly Ethylene Terephthatle (PET) and its PCR.
[030] After the thermoplastics are injected into the injection mold, a preform is formed in the mold itself, having patterned grooves on its inner side. The said patterned grooves on the inner side of the preform correspond to the patterned indetntations on the core rod situated in the injection mold. The said preform is then allowed to cool and subsequently ejected out of the injection mold. After cooling, the preform is reheated at a predetermined temperature, so that it could be subjected to bi-directional stretching, including axial stretching and tangential stretching.
[031] In a preferred embodiment, the reheating temperature is in the range of 90C to 120C.
[032] While being subjected to the axial stretching, the reheated preform is inserted with a stretch rod.
[033] The so stretched preform is then blown by a compressed air at a predefined temperature and pressure, stretched tangentially and ejected to form the container as a final product.
[034] The aforedescribed method is executed by the apparatus comprising of: an injection mold unit for injecting at least one layer of molten thermoplastic material and forming a preform with patterned grooves on its inner side; a reheating unit for reheating the preform; a stretching unit to force axial stretching of the reheated preform; and a blowing unit to blow compressed air at a predetermined temperature to stretch tangentially and form a container as a final product.
[035] In an embodiment where the core rod is provided with the pattern consisting of only plurality of longitudinal indentations or alongwith circumferential indentations, the longitudinal indentations are present in range of 4 to 64 and spaced apart in range of 0.5 mm to 10 mm. In a most preferred embodiment, the longitudinal indentations are present in the range of 20 to 40. In the most preferred embodiment, the spacing between the consecutive longitudinal indetations is 0.7 mm to 1.5 mm. Each of the longitudinal indetations has depth of 0.1 mm to 10 mm. In the most preferred embodiment, each of the longitudinal indetations has depth of 0.2 mm to 1 mm.
[036] In an embodiment as described in the preceeding paragraph, the circumferential indentations are present in range of 4 to 120, spaced apart in range of 0.5 mm to 50 mm, each has depth of 0.1 mm to 10 mm. and each has width of 0.1 mm to 10 mm. In a most preferred embodiment, the adjacent circumferential indentation are spaced apart in range of 0.7 mm to 1.5 mm, each has depth of 0.2 mm to 1 mm and each has width of 0.4 to 1.5 mm.
[037] In an embodiment where the pattern consists of isogrid structured indentations, each of the indentation has a depth of 0.1 mm to 10 mm.
[038] The container so formed by the aforementioned method and apparatus comprises of a neck, and a body made of thermoplastic material. The inner surface of the body has reinforcing pattern, which comprises of plurality of longitudinal ribs, or plurality of circumferential ribs, or a combination of plurality of circumferential & longitudinal ribs.
[039] In an embodiment, the longitudinal ribs are present in range of 4 to 64, are spaced apart in range of 2 mm to 50 mm and have depth of 0.05 mm to 8 mm. and width 0.3 mm to of 30 mm.
[040] In an embodiment, the circumferential ribs are present in range of 4 to 120, are spaced apart in range of 2 mm to 250 mm, and have depth of 0.05 mm to 8 mm, and width of 0.3 to 30 mm.
[041] The container so formed with the method and apparatus described above shows increased compression strength by 10% to 50%.
[042] The container has range of applications from consumer goods, such as storing beverages, to medicines. In case of storing beverages may be a bottle that contains beverages. In case of storing medicines, the container may be a bottle that contains an injectable medicine, or a bottle that contains the swallowing pills. Hence, the term “container” should not be restricted to any particular size and shape, in the context of the present invention. It may be any container for that particular use.

, Claims:1. A method of producing a container comprising:
injecting at least one layer of molten thermoplastic material into an injection mold to form a preform having patterned grooves on its inner side;
ejecting the preform from the injection mold, and subsequently cooling the preform;
reheating the preform at a predetermined temperature;
stretching the reheated preform axially as well as tangentially, wherein the axial stretching is performed by inserting a stretch rod in the reheated preform; and the tangential stretching is performed by blowing the air; and
ejecting the container as a final product,
wherein the container as a final product has a reinforcing pattern at its inner wall corresponding to the patterned grooves on the preform.
2. The method as claimed in Claim 1, wherein the preform having patterned grooves on the inner side correspond to patterned indentations on a core rod in the injection mold.
3. The method as claimed in Claim 2, wherein the patterned indentations on the core rod is selected from plurality of longitudinal indentations, plurality of circumferential indentations, a combination of longitudinal & circumferential indentations, an isogrid structure or any such pattern.
4. The method as claimed in Claim 3, wherein the longitudinal indentations are present in range of 4 to 64.
5. The method as claimed in Claim 3, wherein the adjacent longitudinal indentations are spaced apart in range of 0.5 mm to 10 mm.
6. The method as claimed in Claim 5, wherein the adjacent longitudinal indentations are spaced apart in range of 0.7 mm to 1.5 mm.
7. The method as claimed in Claim 3, wherein each of the longitudinal indentations have depth of 0.1 mm to 10 mm.
8. The method as claimed in Claim 7, wherein each of the longitudinal indentations have depth of 0.2 mm to 1 mm.
9. The method as claimed in Claim 3, wherein each of the longitudinal indentations have width of 0.1 mm to 10 mm.
10. The method as claimed in Claim 9, wherein each of the longitudinal indentations have width of 0.4 mm to 1.5 mm.
11. The method as claimed in Claim 3, wherein the circumferential indentations are present in range of 4 to 120.
12. The method as claimed in Claim 3, wherein the adjacent circumferential indentations are spaced apart in range of 0.5 mm to 50 mm.
13. The method as claimed in Claim 12, wherein the adjacent circumferential indentations are spaced apart in range of 0.7 mm to 1.5 mm.
14. The method as claimed in Claim 3, wherein each of the circumferential indentations has depth of 0.1 mm to 10 mm.
15. The method as claimed in Claim 14, wherein each of the circumferential indentations has depth of 0.2 mm to 1 mm.
16. The method as claimed in Claim 3, wherein each of the circumferential indentations has width of 0.1 mm to 10 mm.
17. The method as claimed in Claim 16, wherein each of the circumferential indentations has width of 0.4 mm to 1.5 mm.
18. The method as claimed in Claim 1, wherein the thermoplastic material is selected from High Density Poly Ethylene (HDPE), Polypropylene (PP), blends of HDPE & PP, Poly Ethylene Terephthalate (PET), PCR (post consumer resins) and such.
19. The method as claimed in Claim 1, wherein compression strength of the container is increased in range of 10% to 50%.
20. A container comprising a neck, and a body made of thermoplastic material; wherein an inner wall of the body includes a reinforcing patterns.
21. The container as claimed in Claim 20, wherein the reinforcing pattern is selected from plurality of longitudinal ribs, plurality of circumferential ribs, a combination of longitudinal & circumferential ribs, an isogrid structured ribs or any such pattern.
22. The container as claimed in Claim 21, wherein the longitudinal ribs are present in range of 4 to 64.
23. The container as claimed in Claim 21, wherein the adjacent longitudinal ribs are spaced apart in range of 2 mm to 50 mm.
24. The container as claimed in Claim 21, wherein each of the longitudinal ribs has depth of 0.05 mm to 8 mm.
25. The container as claimed in Claim 21, wherein each of the longitudinal ribs has width of 0.3 mm to 30 mm.
26. The container as claimed in Claim 21, wherein the circumferential ribs are present in range of 4 to 120.
27. The container as claimed in Claim 21, wherein the adjacent circumferential ribs are spaced apart in range of 2 mm to 250 mm.
28. The container as claimed in Claim 21, wherein each of the circumferential ribs has depth of 0.05 mm to 8 mm.
29. The container as claimed in Claim 21, wherein each of the circumferential ribs has width of 0.3 mm to 30 mm.
30. The container as claimed in Claim 20, wherein compression strength of the container is increased by 10% to 50%.
31. The container as claimed in Claim 20, wherein the thermoplastic material is selected from High Density Poly Ethylene (HDPE), Polypropylene (PP), blends of HDPE & PP, Poly Ethylener Terephthalate (PET), PCR (Post Consumer Resins) and such.