EP1748931A2 - Contenant en polyolefine presentant des caracteristiques de retrait determinees et procede pour produire de tels contenants - Google Patents

Contenant en polyolefine presentant des caracteristiques de retrait determinees et procede pour produire de tels contenants

Info

Publication number
EP1748931A2
EP1748931A2 EP05754304A EP05754304A EP1748931A2 EP 1748931 A2 EP1748931 A2 EP 1748931A2 EP 05754304 A EP05754304 A EP 05754304A EP 05754304 A EP05754304 A EP 05754304A EP 1748931 A2 EP1748931 A2 EP 1748931A2
Authority
EP
European Patent Office
Prior art keywords
container
polypropylene
preform
bottle
preforms
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05754304A
Other languages
German (de)
English (en)
Other versions
EP1748931A4 (fr
Inventor
Jiannong Xu
Bernard Veermeersch
W. Scott Lambert
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Milliken and Co
Original Assignee
Milliken and Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Milliken and Co filed Critical Milliken and Co
Publication of EP1748931A2 publication Critical patent/EP1748931A2/fr
Publication of EP1748931A4 publication Critical patent/EP1748931A4/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/0005—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor characterised by the material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D1/00—Containers having bodies formed in one piece, e.g. by casting metallic material, by moulding plastics, by blowing vitreous material, by throwing ceramic material, by moulding pulped fibrous material, by deep-drawing operations performed on sheet material
    • B65D1/02—Bottles or similar containers with necks or like restricted apertures, designed for pouring contents
    • B65D1/0207—Bottles or similar containers with necks or like restricted apertures, designed for pouring contents characterised by material, e.g. composition, physical features
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
    • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
    • B29C35/08—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation
    • B29C35/0805—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation
    • B29C2035/0822—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation using IR radiation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/42—Component parts, details or accessories; Auxiliary operations
    • B29C49/78—Measuring, controlling or regulating
    • B29C49/783—Measuring, controlling or regulating blowing pressure
    • B29C2049/7831—Measuring, controlling or regulating blowing pressure characterised by pressure values or ranges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/42—Component parts, details or accessories; Auxiliary operations
    • B29C49/78—Measuring, controlling or regulating
    • B29C49/783—Measuring, controlling or regulating blowing pressure
    • B29C2049/7832—Blowing with two or more pressure levels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/42—Component parts, details or accessories; Auxiliary operations
    • B29C49/78—Measuring, controlling or regulating
    • B29C49/786—Temperature
    • B29C2049/7861—Temperature of the preform
    • B29C2049/7862—Temperature of the preform characterised by temperature values or ranges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/42—Component parts, details or accessories; Auxiliary operations
    • B29C49/78—Measuring, controlling or regulating
    • B29C2049/7879—Stretching, e.g. stretch rod
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2949/00—Indexing scheme relating to blow-moulding
    • B29C2949/07—Preforms or parisons characterised by their configuration
    • B29C2949/0715—Preforms or parisons characterised by their configuration the preform having one end closed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2949/00—Indexing scheme relating to blow-moulding
    • B29C2949/07—Preforms or parisons characterised by their configuration
    • B29C2949/072—Preforms or parisons characterised by their configuration having variable wall thickness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2949/00—Indexing scheme relating to blow-moulding
    • B29C2949/07—Preforms or parisons characterised by their configuration
    • B29C2949/081—Specified dimensions, e.g. values or ranges
    • B29C2949/0811—Wall thickness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2949/00—Indexing scheme relating to blow-moulding
    • B29C2949/07—Preforms or parisons characterised by their configuration
    • B29C2949/081—Specified dimensions, e.g. values or ranges
    • B29C2949/082—Diameter
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2949/00—Indexing scheme relating to blow-moulding
    • B29C2949/07—Preforms or parisons characterised by their configuration
    • B29C2949/0861—Other specified values, e.g. values or ranges
    • B29C2949/0862—Crystallinity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2949/00—Indexing scheme relating to blow-moulding
    • B29C2949/20—Preforms or parisons whereby a specific part is made of only one component, e.g. only one layer
    • B29C2949/22—Preforms or parisons whereby a specific part is made of only one component, e.g. only one layer at neck portion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2949/00—Indexing scheme relating to blow-moulding
    • B29C2949/20—Preforms or parisons whereby a specific part is made of only one component, e.g. only one layer
    • B29C2949/24—Preforms or parisons whereby a specific part is made of only one component, e.g. only one layer at flange portion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2949/00—Indexing scheme relating to blow-moulding
    • B29C2949/20—Preforms or parisons whereby a specific part is made of only one component, e.g. only one layer
    • B29C2949/26—Preforms or parisons whereby a specific part is made of only one component, e.g. only one layer at body portion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2949/00—Indexing scheme relating to blow-moulding
    • B29C2949/20—Preforms or parisons whereby a specific part is made of only one component, e.g. only one layer
    • B29C2949/28—Preforms or parisons whereby a specific part is made of only one component, e.g. only one layer at bottom portion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2949/00—Indexing scheme relating to blow-moulding
    • B29C2949/30—Preforms or parisons made of several components
    • B29C2949/3024—Preforms or parisons made of several components characterised by the number of components or by the manufacturing technique
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2949/00—Indexing scheme relating to blow-moulding
    • B29C2949/30—Preforms or parisons made of several components
    • B29C2949/3032—Preforms or parisons made of several components having components being injected
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/02—Combined blow-moulding and manufacture of the preform or the parison
    • B29C49/06—Injection blow-moulding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/08—Biaxial stretching during blow-moulding
    • B29C49/087—Means for providing controlled or limited stretch ratio
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/08—Biaxial stretching during blow-moulding
    • B29C49/10—Biaxial stretching during blow-moulding using mechanical means for prestretching
    • B29C49/12—Stretching rods
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/42—Component parts, details or accessories; Auxiliary operations
    • B29C49/4205—Handling means, e.g. transfer, loading or discharging means
    • B29C49/42093—Transporting apparatus, e.g. slides, wheels or conveyors
    • B29C49/42095—Rotating wheels or stars
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/10—Polymers of propylene
    • B29K2023/12—PP, i.e. polypropylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2067/00—Use of polyesters or derivatives thereof, as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2623/00—Use of polyalkenes or derivatives thereof for preformed parts, e.g. for inserts
    • B29K2623/10—Polymers of propylene
    • B29K2623/12—PP, i.e. polypropylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/712—Containers; Packaging elements or accessories, Packages
    • B29L2031/7158—Bottles
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
    • Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]

Definitions

  • Injection stretch blow molding is a process of producing thermoplastic articles, such as liquid containers. This process involves the initial production of a preform articles by injection molding. Then, the preform article that after reheating is subjected to stretching and gas pressure to expand (blow) the preform article against a mold surface to form a container. There are several different processes that employ stretch blow molding.
  • a first type is a single stage process in which a preform is made on a machine and allowed to cool somewhat to a predetermined blow molding temperature. While still at this elevated temperature, the preform is stretch blow molded into a container on the same machine, as part of a single manufacturing procedure. This is a one step or so-called "single stage" manufacturing procedure.
  • the temperature of the preform is cooled (reduced) following preform formation from about 230°C to about 120-140°C.
  • the preform is not returned to ambient temperature, but instead is blown to a container while at about 120 to 140°C.
  • Another type of process is a two stage process. In a two stage process, preforms first are formed in an injection machine.
  • preforms are cooled to ambient temperature.
  • preforms are shipped from one location to another (or from one company to another) prior to stretch blowing the preforms into containers.
  • preforms are heated from an initial ambient temperature to an elevated temperature for stretch blowing on a molding machine to form a container.
  • the injection machine and the molding machine typically are located apart from one another in such a two stage procedure.
  • Two stage manufacturing processes are sometimes referred to as "reheat stretch blow molding" (RSBM) processes, because preform articles formed in the first stage are subsequently reheated during the second stage of manufacture to form finished containers.
  • RSBM reheat stretch blow molding
  • Figure 1 shows a typical polypropylene container that may be manufactured according to the process of the invention
  • Figure 2A is a schematic flow diagram showing the processing steps employed in the first stage of the two stage process, which relates to injection manufacture of preform articles
  • Figure 2B illustrates processing steps in the second stage of manufacturing in accord with the invention, wherein a preform article is stretch blow molded to form a container
  • Figure 3 is a side view of a conventional thick-walled preform article
  • Figure 3A shows a side cross-sectional view of the conventional preform article of Figure 3
  • Figures 3B and 3C show a first embodiment of a relatively thin walled preform with an external profile that may be employed in the invention
  • Figure 4 shows a side view of a second preform that may be used in the invention, i.e.
  • Figure 4A shows a cross-sectional view of the thin-walled preform article of Figure 4
  • Figure 5 is a longitudinal sectional view of an injection molding assembly for the production of a preform article
  • Figure 6 is an illustration of stage two of the manufacturing process, showing a vertical cross-sectional view of stretch blow mold apparatus that is used to produce the containers from a perform, in this view showing a start up position with the preform article in place
  • Figure 7 is a view of the apparatus of Figure 6 showing the mold closed on the preform article
  • Figure 8 shows a fully blown container with a stretch rod and swage in a down position with the container decompressing in the mold.
  • a two-stage process of injection stretch blow molding polypropylene to form a container is disclosed in the practice of the invention.
  • a first stage of this process comprises forming a preform article.
  • a second subsequent stage comprises reheating and blow molding the preform article to form a container.
  • the invention is directed to both preform articles and containers, in addition to the specific method or process for forming these products.
  • a polypropylene container is made by an injection stretch blow molding two stage process.
  • the container has: a) a side wall providing a haze value of less than 3 according to ASTM D 1003, b) an MFI (melt flow index) between about 6 g/10min and about 50 g/10min according to ASTM D 1238; c) wherein the average wall thickness of the container after subjecting the container to the free shrinkage test (see Example 17 below) is less than about
  • a process having at least the following steps. First, a chemical composition comprising at least in part polypropylene is provided. This chemical composition provides a melt flow index in the range of between about 6 and about 50 grams/10 minutes, according to ASTM D 1238 at 230 degrees C/2.16 kg. Further, the chemical composition is injected into a mold at a fill rate of greater than about 5 grams of chemical composition per second. This injection may be made through an orifice or gate, as further described herein. A preform article is formed in a mold. The preform article is removed from the mold. The preform article includes a closed end adapted for subsequent second stage reheating and stretch blow molding.
  • the closed end may be integral with a side wall.
  • the side wall of the preform provides a thickness of less than about 3.5 mm, in one aspect of the invention.
  • Processing parameters are employed in the practice of the invention to produce preform articles that facilitate fast and efficient stretch blow molding to produce containers having a desirably low haze.
  • the melt flow index (MFI) of the polypropylene chemical compositions i.e. resins
  • MFI melt flow index
  • the invention has overcome limitations in the art, in part by the unexpected discovery that processing parameters may be established to impart necessary conditions and benefits to form superior polypropylene-based preforms.
  • This invention facilitates efficient and cost-effective production of clear, low haze polypropylene articles from preforms using injection to make a preform, followed in some instances by stretch blow molding to form a container.
  • the advantages of the process disclosed herein comprise, among other things, appropriate selection of melt flow polypropylene resins, appropriate selection of nucleating and clarifying agents, appropriate thickness of performs, appropriate rate or speed of injecting the resin for preform production, and also perhaps the appropriate gate width during preform production.
  • polypropylene has long been known to exist in several forms, and essentially any known form could be used in the practice of the invention. Thus, the invention is not limited to any particular type of polypropylene.
  • Isotactic propylene iPP
  • sPP syndiotactic polypropylene
  • container articles produced in accordance with the criteria noted above exhibit specific haze to thickness ratios, and such is within the scope of the present invention.
  • the invention provides a vast improvement in polypropylene injection stretch blow-molded article technology whereby efficient methods of producing very clear articles is accorded as proper replacements for previous PET types.
  • the practice of the invention makes it possible to provide injection stretch blow-molded polypropylene articles that may be produced at very high rates and exhibit substantially uniform clarity levels.
  • the invention may provide polypropylene preforms that facilitate production of very low haze container articles with injection stretch blow molding in a very efficient manner.
  • One application of the invention provides improved containers, wherein such containers (or bottles) exhibit low haze levels.
  • An effective clarifying agent, that also functions as a nucleator, for polypropylene is 1 ,3-O-2,4-bis(3,4-dimethylbenzylidene) sorbitol (hereinafter DMDBS), available from Milliken & Company under the trade name Millad® 3988.
  • DMDBS 1 ,3-O-2,4-bis(3,4-dimethylbenzylidene) sorbitol
  • Such a compound provides highly effective haze reductions within polypropylenes with concomitant low taste and odor problems.
  • Disubstituted DBS compounds are broadly described in U.S. Patent Numbers 5,049,605 and 5,135,975 to Rekers.
  • DMDBS is a useful compound for such a result.
  • An effective thermoplastic nucleator in terms of high crystallization temperatures is available from Milliken & Company using the trade name HPN- 68TM.
  • HPN-68TM Other like thermoplastic nucleating compounds that may be employed in the practice of the invention are disclosed in U.S. Patent Numbers. 6,465,551 and 6,534,574.
  • the HPN-68TM compound is disodium bicyclo[2.2.1]heptanedicarboxylate.
  • nucleating agent The ability to provide highly effective crystallization, or, in this specific situation, control targeted levels of crystallization within polypropylene preforms prior to injection stretch blow molding sometimes is facilitated by utilization of such a nucleating agent. Low amounts of this additive can be provided to produce the desired and intended amorphous-crystalline combination within the target performs.
  • Other nucleating agents can be employed in the practice of the invention.
  • polypropylene polymers employed in the practice of the invention may include homopolymers (known as HPs), impact or block copolymers (known as ICPs)(combinations of propylene with certain elastomeric additives, such as rubber, and the like), and random copolymers (known as RCPs) made from at least one propylene and one or more ethylenically unsaturated comonomers.
  • HPs homopolymers
  • ICPs impact or block copolymers
  • RCPs random copolymers
  • co-monomers if present, constitute a relatively minor amount, i.e., about 10 percent or less, or about 5 percent or less, of the entire polypropylene, based upon the total weight of the polymer.
  • co-monomers may serve to assist in clarity improvement of the polypropylene, or they may function to improve other properties of the polymer.
  • Co-monomer examples include acrylic acid and vinyl acetate, polyethylene, polybutylene, and other like compounds.
  • Polypropylene provides an average molecular weight of from about 10,000 to about 2,000,000, preferably from about 30,000 to about 300,000, and it may be mixed with additives such as polyethylene, linear low density polyethylene, crystalline ethylenepropylene copolymer, poly(l-butene), 1- hexene, 1-octene, vinyl cyclohexane, and polymethylpentene, as examples.
  • Resin compositions utilized to produce the preform articles and injection stretch blow-molded containers of the invention can be obtained by adding a specific amount of a nucleating agent/clarifying agent directly to the polypropylene, either in dry form or in molten form, and mixing them by any suitable means while in molten form to provide a substantially homogenous formulation.
  • a concentrate containing as much as about 20 percent by weight of a nucleator/clarifier in a polypropylene masterbatch may be prepared and be subsequently mixed with the resin.
  • the desired nucleator/clarifier may be present in any type of standard polypropylene additive form, including, without limitation, powder, pill, agglomerate, liquid suspension, and the like, particularly comprising dispersion aids such as polyolefin (e.g., polyethylene) waxes, stearate esters of glycerin, waxes, mineral oil, and the like.
  • dispersion aids such as polyolefin (e.g., polyethylene) waxes, stearate esters of glycerin, waxes, mineral oil, and the like.
  • any form may be exhibited by such a combination or composition including such combination made from blending, agglomeration, compaction, and/or extrusion.
  • the produced resins are then utilized to form preforms, as noted herein, which are then subsequently utilized to form the desired container articles in an injection stretch blow molding procedure.
  • organoleptic improvement additives be added for the purpose of reducing the migration of degraded benzaldehydes from reaching the surface of the desired article.
  • organoleptic improvement additive is intended to encompass such compounds and formulations as antioxidants (to prevent degradation of both the polyolefin and possibly the target alditol derivatives present within such polyolefin), acid neutralizers (to prevent the ability of appreciable amounts of residual acids from attacking the alditol derivatives), and benzaldehyde scavengers (such as hydrazides, hydrazines, and the like, to prevent the migration of foul tasting and smelling benzaldehydes to the target polyolefin surface).
  • Polypropylene compositions having an melt flow index (MFI) of between about 6 and about 60 are useful in the practice of the invention. Furthermore, MFI values of between about 13 and about 35 are particularly useful in the practice of the invention, as further described below.
  • An injection speed of the chemical composition (i.e. polypropylene and various additives) into a preform cavity mold at a fill rate of greater than about 5 grams of chemical composition per second has been found to be particularly valuable in the practice of the invention.
  • Table A shows values for various parameters that may be employed in the practice of the invention, as further discussed herein. In addition to the injection speed of the specific MFI resin, the thickness and design of the target preform is important for a number of reasons.
  • the thickness of such an article should be thin, as compared with the thickness of previously produced polypropylene preforms. This facilitates low haze results as noted above, and also facilitates utilization within prior PET injection stretch blow molding machinery.
  • the side wall thickness of preforms desirably may be less than about 3.5 mm for effective results. In some applications, side wall thickness of between about 1.5 mm and 3.5 is very useful. Some applications may use a thickness of as much as 4.0 mm, as set forth in Table A.
  • a gate as further described herein, comprises the opening through which liquid chemical composition (polypropylene and additive mixture) is admitted into the preform mold cavity. The gate diameter employed during preform production is particularly important, and may be related to other processing variables.
  • FIG. 1 shows a stretch blow molded polypropylene container that may be manufactured in accordance with the practice of the invention.
  • Container 10 (sometimes referred to herein as a "bottle") is shown.
  • the container 10 of Figure 1 has a relatively concave bottom 11 , a cylindrical main sidewall 12, a conical upper portion 13, and a thickened externally threaded neck 14 on the convergent end of the upper portion 13.
  • a neck ring 15 provides a physical point of reference, and may be used to carry the container 10 along processing machinery during manufacture and subsequent filling of the container 10.
  • the container 10 may be of any desired size or shape with sizes of from 0.5 to 4 liters being very useful, for example.
  • the neck 14 usually is rigid to support a pressure retaining screw type cap (not shown). Thus, the neck 14 may be many times the thickness of the sidewall 12.
  • the conical upper portion 13 may be gradually thickened as it approaches neck 14.
  • FIG. 2A a flow schematic is provided showing the steps in the first stage of a two-stage stretch blow molding process.
  • a two stage (two steps) procedure is provided for production of containers 10.
  • Figure 2A shows the first stage of the manufacturing procedure, that is, the injection molding process of preforms production.
  • a chemical composition containing polypropylene is acquired from a source, such as a polypropylene manufacturer.
  • the polypropylene-containing chemical composition may comprise a homopolymer, copolymer or other polymeric composition.
  • the chemical composition may contain various additives, including (for example) nucleating agents, antioxidants, lubricants, s-scavengers, UV absorbers and the like, as further described herein.
  • the polypropylene chemical composition is provided into an injection machine and heated. The heated chemical composition then is injected at a relatively high rate of speed through a valve or "gate", and into the mold of the injection machine. A preform article is formed in a mold. The preform article is cooled and removed from the mold.
  • Figure 2B shows a second stage of a two-stage stretch blow molding process. In the second stage, a preform article (which may or may not have been manufactured at a location distant from the stretch blow molding apparatus) is converted to a container 10.
  • a preform article (usually at ambient temperature) is provided in a stretch blow molding machine. Then, the preform article is heated from ambient temperature to an elevated temperature.
  • the elevated temperature employed is also known as the "orientation" temperature, and it is typically in the range of about 120-130°C for random copolymers.
  • the inner surface temperature of the preform needs to be sufficiently high to ensure that containers have the best optical properties. This has been found to be one important variable in the stretch blow molding process which sometimes determines whether the container will be transparent or hazy.
  • the preform article is sufficiently softened, the preform is stretch blow molded into a container 10. The formed container 10 is cooled and removed from the stretch mold apparatus.
  • FIGS 3-3A show a thick-walled polypropylene preform having a relatively thick side wall 80 (in this example, the side wall thickness is about 5 mm).
  • the preform article 60 shown in Figure 3 includes a closed end 62 and an open end 72. Furthermore, a neck 66 is shown, with threads 68 at the base of the neck 66. A main body portion 64 with side wall 80 is shown. It is common for polypropylene-based preforms 60 such as that shown in Figure 3 to have a * side wall 80 having a thickness of about 5 mm, or more. This preform article 60 happens to also be "stepped out" or tapered at each end, on its exterior profile.
  • FIG. 3B and corresponding Figure 3C show a first embodiment of a thin walled preform article that may be employed in the practice of the invention. It should be noted that the invention may include the use of "stepped out" preforms with an exterior profile, such as shown in Figures 3B/3C so long as the preforms are less than about 3.5 mm in side wall width.
  • one discovery of the invention is that thin-walled preforms, in conjunction with processing conditions presented herein, provide surprisingly unexpected results as compared to conventional thick walled preforms.
  • a preform 90 having thin side wall 91 is shown.
  • Second Type of Preform Article Employed in the Invention The geometry of a preform article is important in the manufacturing of containers 10.
  • a preform article 115 having a relatively thin side wall may be employed, as further described herein and as shown in Figures 4-4A.
  • the geometry of the preform article 115 of Figure 3 shows a tapered neck 114, and a main body portion 102 with side walls 101 and 104 that are approximately parallel to each other along their length.
  • a closed end portion 116 tapers from the main body portion 102. Threads 110 are provided adjacent the open end 103 of preform article 115.
  • a transition area 105 represents the tapering region of the side wall 101 into the neck 114.
  • a preform article 115 of the invention is shown in which the outer wall surfaces 109a-b of the preform article are generally parallel and straight, forming a substantially symmetrical tube on its outer dimension from a point near the closed end 116 to a point near the open end 103.
  • the inner wall 108 of the preform 115 is profiled due to a transition zone 105. When blown in stage two of manufacture, the preform article 115 engages a mold so as to make a container 10 of the appropriate geometry.
  • profiled it is meant that a given wall has a changing angle or slope which deviates from 180 degrees.
  • the invention may in some embodiments take advantage of a profiled inner wall 108, as opposed to a profiled exterior wall, as is common in the conventional devices (see Figures 3- 3A).
  • the use of a profiled inner wall 108 has been found to be a useful feature in application of the preform 115 to container 10 manufacture.
  • One reason for this fact is that it facilitates the use of relatively uniform outer wall dimensions.
  • preforms 115 can be used that have differing inner wall 108 profile for various container sizes, while still exhibiting a common outer dimension or shape.
  • FIG. 5 shows a schematic vertical cross-sectional view of an injection molding machine for making preform articles in a first stage.
  • a preform article 115 may be formed in an injection molding unit 120 having a barrel 121 fed by an hopper 122 and ejecting the melt through a round nose nozzle 123.
  • a chemical composition i.e. polypropylene-containing pellets or portions, with optional additives or optional nucleating agents, etc) is provided into inlet hopper 122.
  • Barrel 121 rotatably mounts a melting and mixing screw 124 with a non- return valve nose 125.
  • Heater bands 126 may be provided in the barrel 121.
  • Crystalline polypropylene stretch blow mold formulations are fed through the hopper 122 into the barrel 121 where they are advanced by the melting and mixing screw 124 to a molten condition at the valve end 125 whereupon the screw is advanced to the dotted line position where the valve nose 125 will force the molten material through the nozzle orifice 127.
  • Gate 137a received a determined the amount of liquid flow that proceeds into the molding cavity 135.
  • Other similar apparatus could be used to form a preform, which achieves the same or similar result as that shown in Figure 5.
  • the apparatus includes a two-part mold 130 with a first core part 131 and a second molding cavity defining part 132.
  • the part 131 has a cylindrical core 133 with a hemispherical end 134.
  • the part 132 has a molding cavity 135 with a hemispherical bottom end 136 fed by a conduit 137.
  • the end wall of the part 132 has a recess 138 receiving the rounded nose of the nozzle 123.
  • Chilled mold temperatures from about 11 - 20 degrees C. may be employed.
  • the gate 137a refers is the opening between the point at which the liquid polypropylene is injected and the actual core 134 of the mold cavity 135.
  • Gate size is a parameter that may vary for different applications.
  • the size of the gate 137a can be important in the manufacture of preformed articles 115. This is because the size of the gate 137a determines the shear forces applied to the molten polypropylene as it is injected into the mold cavity. The size of gate 137a will affect the filing rate.
  • the size of the gate 137a will in some cases determine the rate by at which the chemical composition may be injected, which affects the ultimate clarity of the containers 10 produced by the preformed article 115 in the second stage of the container 10 manufacture (see Figure 2B).
  • the clarity of the container 10 produced may be compromised because of the characteristics imparted to the preform article 115 during such mold fill step.
  • Gate diameter may vary, depending upon the application.
  • the invention is not limited to any particular gate diameter, but it has been found that diameters between about 1.5 mm and about 3.8 mm are useful, and may be found in equipment in the industry. It may be an advantage in the practice of the invention to be capable of employing gate diameter settings that already are in existence and used on existing commercial PET processing equipment.
  • the injection rate usually is relatively slow. Cavity filling time is typically about 1 to about 4.5 total seconds to fill mold cavity 135. This corresponds generally to an injection rate greater than about 5 grams/second. In other cases, the rate may be between about 5 and about 22 grams per second. Table A shows various parameters that may be advantageously employed in the practice of the invention.
  • melt flow index also known as the melt flow rate
  • melt flow index is an important factor in the manufacturing of preform articles 115.
  • melt flow index is measured according to American Society of Testing Materials ASTM D-1238. This testing method is a nationally (or internationally) known standard. It is a standard test method for measuring the melt flow rates of thermoplastics. Unless otherwise indicated herein, all references to melt flow index, melt flow rate, MFI, or MFR, refer to measurements according to this industry standard.
  • MFI For polypropylene, measurements are at 230 degrees C, and using 2.16 kg, as per this standard. In general, the more viscous is a material at a given temperature, the lower will be the MFI value of that material.
  • a given polymer or copolymer composition will have an MFI that is specified by a manufacturer.
  • each particular type of polypropylene-containing composition to be employed in the practice of the invention will have a given or predetermined MFI. The MFI is also determined and affected by the length of the polymer chains in a given polypropylene composition. The longer the polymeric chains, the more viscous the material. The more viscous the material, the lower the MFI value will be for a given composition.
  • MFI values are important in determining the speed at which a chemical composition may be fed into an injection mold cavity to form a preform article. This is true because the MFI also will affect the clarity of the final container which is produced from the preform. By clarity, it is meant the degree of haze that will be present in a given container 10 made according to the invention. In general, the higher percentage of haze in the container 10, the less transparent is the container 10 produced in the invention. Higher levels of haze are undesirable.
  • One unexpected result of the invention is that it has been found that using a given polymeric composition having a predetermined melt flow index, and injecting that composition at a fill rate of greater than about 5 grams per second, a highly desired preform article may be formed.
  • the sidewall thickness of the preform is very important in container manufacture.
  • a preform article 115 with a side wall thickness of less than about 3.5 millimeters has proved to be very desirable. This achieves a high productivity of container manufacture while still maintaining a low degree of haze, i.e. a clear container.
  • Cycle time necessary to make a preform article 115 is significantly reduced by using a preform design with a minimum side wall thickness.
  • Hot plastic polypropylene
  • Stretch Blow Molding Preform Articles to Form Containers Stage two (step 2) of manufacture is shown generally in Figures 2B, and Figures 6-8.
  • a preform article 115 is taken at ambient temperature, and then uniformly heated.
  • the preform article 115 is placed in a stretch blow mold apparatus 140 in a position with its open end 103 resting on a platform 141 on a base 142 surrounding a reciprocal swage 143.
  • the closed end 116 of the preform 115 is shown near the center of Figure 6.
  • the apparatus freely receives the retracted end of the stretch rod 144 of the apparatus 140.
  • the molding dies 145 of the apparatus 140 are in an opened condition.
  • Threaded neck forming wall portions 146 are shown, as well as tapered cone forming portions 147, cylindrical main body forming portions 148, and concave bottom forming portions 149.
  • a rotary system is employed to transfer preforms using transfer wheels equipped with grippers into a blow mold cavity.
  • rotary stretch blow molding equipment is known in the art, and may be applied in the practice of the invention. From the open position of Figure 6 the apparatus 140 is closed to the position of Figure 7 with the mold halves 145 coming together and with the swage 143 extended into the open end of the preform 115 so that the neck and thread forming portions 146 of the die can mold the thick neck 114 of the bottle on the preform 115.
  • the projection of the swage 143 into the position of Figure 7 also moves the stretch rod 144 against the closed end 116 of the preform 115. From the position of Figure 7 the apparatus 140 is further activated to eject the stretch rod 144 beyond the swage 143 into closely spaced relation from the bottom forming portion 149 of the dies 145 thereby effecting a stretching of the preform 115 to the full height of the dies. As shown in Figure 8, the stretch rod 144 and the swage 143 are retracted from the container 10. The gas pressure in the bottle is released, and the dies 45 are separated. A blowing agent is introduced into the preform article 115 forming an axially elongated and hoop stretched balloon in the closed die.
  • the balloon (not shown) is blown into a finished container 10, as shown in Figure 8, with the polypropylene material biaxially stretched to produce a strong container 10.
  • Roughness on the inner container 10 surface has a negative influence on the container clarity. If, during reheating of the preform 1 15 (within the window of process stability), the temperature in the skin-layer (at the side of the core) is insufficiently high, the material undesirably may be ruptured apart during the stretch blow molding (stage two) process, resulting in a rough inner container 10 surface and containers 10 having low clarity. Additionally, it has been observed that a low amount of "pre-blowing" (intermediate shape of the stretched and pre- blown preform part, i.e.
  • a preform thickness may be of a value less than about 3.5 mm. Thickness is measured along side walls 101 ,104 as shown in Figure 4A, measured as the maximum or thickest portion of the side wall. In yet another embodiment of the invention, the preform thickness may be in the range of about 2 - 3.5 mm.
  • an injection fill rate into the cavity mold of greater than about 5 grams of chemical composition (resin) per second is quite useful.
  • Table A shows a correlation between processing variables in the practice of the invention.
  • the MFI values and preform wall thickness values are correlated to the optimized injection mold filling rate in the practice of the invention. It is important to note in Table A that for a given preform wall thickness an increase in the MFI value allows an operator to use a higher injection mold filling rate while still obtaining containers 10 of sufficient clarity.
  • valve gate diameter of 3.8mm at MFI value 20 may result in an injection speed of about 22 g/sec. This value of 22 g/sec may be compared to the injection speed shown in Table A (valve diameter 1.5 mm) of 5-7 g/s.
  • Example 1 - 38 mm neck. 4 mm wall preforms Commercial random copolymer resins containing Millad 3988 (Borealis) were used to produce preforms as indicated in Table I.
  • the preforms were produced on a two-cavity mold (only one cavity installed) 100 ton Netstal injection molding machine with a variable injection time (0.5-4.0 sec) and a constant cooling time of 22 sec. Melt temperature was 230 C C. Temperature of the cooling water was 13°C. The holding pressure time was 9.2 sec. Total cycle time was around 37 sec (not optimized). A valve gate with a diameter of 1.5 mm was used.
  • the preforms have a wall thickness of 4 mm and a bottle weight of about 25.3g. These preforms were later blown into bottles as explained in subsequent examples. Table I.
  • Example 1 Preforms have a wall thickness of 4 mm and a bottle weight of about 25.3g. These preforms were later blown into bottles as explained in subsequent examples. Table I.
  • Example 2 - 38 mm neck, 3 mm wall preforms Commercial random copolymer resins containing Millad 3988 (Borealis) were used to produce preforms as indicated in Table II.
  • the preforms were produced on a two-cavity mold (only one cavity installed) 100 ton Netstal injection molding machine with a variable injection time (0.5-4.0 sec) and a constant cooling time of 10 sec. Melt temperature was 230°C. Temperature of the cooling water was 13°C. The holding pressure time was 4.5 sec. Total cycle time was around 20 sec (not optimized). A valve gate with a diameter of 1.5 mm was used.
  • the preforms have a wall thickness of 3 mm and a bottle weight of about 20.3g. These preforms were later blown into bottles as explained in subsequent examples.
  • Example 3 - 38 mm neck, 2 mm wall preforms Commercial random copolymer resins containing Millad 3988 (Borealis) were used to produce preforms as indicated in Table III.
  • the preforms were produced on a two-cavity mold (only one cavity installed) 100 ton Netstal injection molding machine with a variable injection time (0.5-4.0 sec) and a constant cooling time of 10 sec. Melt temperature was 230°C. Temperature of the cooling water was 13°C. The holding pressure time was 2 sec. Total cycle time was around 20 sec (not optimized). A valve gate with a diameter of 1.5 mm was used.
  • the preforms have a wall thickness of 2 mm and a bottle weight of about 17.3g. These preforms were later blown into bottles as explained in subsequent examples. Table III.
  • Polypropylene bottles (330 ml) were on a two-cavity Chia-Ming stretch blow molding machine designed to blow polypropylene bottles from preforms described in Example 1.
  • Axial stretch ratio is 1.9/1
  • Hoop Stretch ratio 2.5/1
  • Total Stretch Ratio 4.8/1.
  • This machine is equipped with 3 heater boxes per cavity & uses 1000 Watt IR lamps.
  • Pre-blow pressure was 6 bar & final pressure was 8 bar. After optimization, the bottle productivity for the preforms with 4 mm thickness was 820 bph/cav.
  • Bottle quality was judged at the time of production to be Unacceptable (poorly blown bottle or blown out), Acceptable (a fully blown bottle with moderate optical properties), Average (a fully blown bottle with improved optical properties), or Excellent (a fully blown bottle with outstanding optical clarity). Table IV. Example 4 Bottles
  • Polypropylene bottles (330 ml) were blown at high speed on a two-cavity Chia-Ming stretch blow molding machine designed to blow polypropylene bottles from preforms described in Example 2.
  • Axial stretch ratio is 1.9/1
  • Hoop Stretch ratio 2.4
  • Total Stretch Ratio 4.6/1.
  • This machine is equipped with 3 heater boxes per cavity & uses 1000 Watt IR lamps.
  • Pre-blow pressure was 6 bar & final pressure was 8 bar. After optimization, the bottle productivity for the preforms with 3 mm thickness was 1 ,030 bph/cav.
  • Bottle quality was judged at the time of production to be Unacceptable (poorly blown bottle or blown out), Acceptable (a fully blown bottle with moderate optical properties), Average (a fully blown bottle with improved optical properties), or Excellent (a fully blown bottle with outstanding optical clarity).
  • Polypropylene bottles (330 ml) were blown at high speed on a two-cavity Chia-Ming stretch blow molding machine designed to blow polypropylene bottles from preforms described in Example 3.
  • Axial stretch ratio is 1.9/1
  • This machine is equipped with 3 heater boxes per cavity & uses 1000 Watt IR lamps.
  • Pre-blow pressure was 6 bar & final pressure was 8 bar. After optimization, the bottle productivity for the preforms with 2 mm thickness was 1 ,200 bph/cav.
  • Bottle quality was judged at the time of production to be Unacceptable (poorly blown bottle or blown out), Acceptable (a fully blown bottle with moderate optical properties), Average (a fully blown bottle with improved optical properties), or Excellent (a fully blown bottle with outstanding optical clarity).
  • Example 7 - 38 mm neck bottles produced using new ISBM machine with 4 mm preforms Polypropylene bottles (500 ml) were blown at high speed (1500 bottles/cavity/hour) on a Sidel SBO-8 Series II stretch blow molding machine designed to blow PET preforms using the polypropylene preforms described in Example 1.
  • Axial stretch ratio is 2.5/1
  • Machine settings were adjusted to accommodate high clarity, high speed bottle production.
  • Preforms were subjected to a pre-blow pressure of 3 Bar for 0.9 seconds with the preform inner temperature set to about 125° - 130° C and the outer temperature set to about 120° - 125° C. Heating power distribution was managed in the range of 90%.
  • Bottle quality was judged at the time of production to be Unacceptable (poorly blown bottle or blown out), Acceptable (a fully blown bottle with moderate optical properties), Average (a fully blown bottle with improved optical properties), or excellent (a fully blown bottle with outstanding optical clarity).
  • Polypropylene bottles (500 ml) were blown at high speed (1 ,500 bottles/cavity/hour) on a Sidel SBO-8 Series-ll stretch blow molding machine designed to blow PET preforms using the polypropylene preforms described in Example 2.
  • Axial stretch ratio is 2.5/1
  • Hoop Stretch ratio 2.54
  • Total Stretch Ratio 6.36/1.
  • Machine settings were adjusted to accommodate high clarity, high speed bottle production.
  • Preforms were subjected to a pre-blow pressure of 4.5 Bar for 0.4 seconds & nozzle for 3 rotations open activated at 'point zero'.
  • Blowing time is 0.8 sec & Exhaust time is 0.4 sec.
  • Stretch speed is 1 ,384 m/sec & a standard stretch rod with 14 mm diameter was used.
  • Preform temperature is about 120-130°C.
  • Bottle quality was judged at the time of production to be Unacceptable (poorly blown bottle or blown out), Acceptable (a fully blown bottle with moderate optical properties), Average (a fully blown bottle with improved optical properties), or Excellent (a fully blown bottle with outstanding optical clarity).
  • Polypropylene bottles (500 ml) were blown at high speed (1 ,500 bottles/cavity/hour) on a Sidel SBO-8 Series-ll stretch blow molding machine designed to blow PET preforms using the polypropylene preforms described in Example 3.
  • Axial stretch ratio is 2.5/1
  • Hoop Stretch ratio 2.54
  • Total Stretch Ratio 6.36/1.
  • Machine settings were adjusted to accommodate high clarity, high speed bottle production.
  • Preforms were subjected to a pre-blow pressure of 4 Bar for 0.4 seconds & nozzle for 3 rotations open activated at 'point zero'.
  • Blowing time is 0.8 sec & Exhaust time is 0.4 sec.
  • Stretch speed is 1 ,384 m/sec & a standard stretch rod with 14 mm diameter was used.
  • Preform temperature is about 115-127°C.
  • % GP 45 %.
  • Bottle quality was judged at the time of production to be Unacceptable (poorly blown bottle or blown out), Acceptable (a fully blown bottle with moderate optical properties), Average (a fully blown bottle with improved optical properties), or Excellent (a fully blown bottle with outstanding optical clarity).
  • Example 10 - 38 mm neck. 3 mm wall preforms Several compounds were produced on a Killion single screw extruder at a temperature 230°C using 25 g/10 min random copolymer polypropylene fluff.
  • the preforms (ref. Table X) were produced on a two-cavity mold (only one cavity installed) 100 ton Netstal injection molding machine with a variable injection time (0.5-4.0 sec) and a constant cooling time of 10 sec. Melt temperature was 230°C. Temperature of the cooling water was 13°C. The holding pressure time was 4.5 sec. Total cycle time was around 20 sec (not optimized). A valve gate with a diameter of 1.5 mm was used.
  • the preforms have a wall thickness of 3 mm and a bottle weight of about 20.3g. These preforms were later blown into bottles as explained in subsequent examples. Table X.
  • Example 10 Preforms have a wall thickness of 3 mm and a bottle weight of about 20.3g. These preforms were later blown
  • Polypropylene bottles (330 ml, ref. Table XI) were produced blown at high speed on a two-cavity Chia-Ming stretch blow molding machine designed to blow polypropylene bottles from preforms described in Example 10.
  • Axial stretch ratio is 1.9/1
  • Hoop Stretch ratio 2.4
  • Total Stretch Ratio 4.6/1.
  • This machine is equipped with 3 heater boxes per cavity & uses 1000 Watt IR lamps.
  • Pre-blow pressure was 6 bar & final pressure was 8 bar.
  • the bottle productivity for the preforms with 3 mm thickness was 1 ,030 bph/cav.
  • Bottle quality was judged at the time of production to be Unacceptable (poorly blown bottle or blown out), Acceptable (a fully blown bottle with moderate optical properties), Average (a fully blown bottle with improved optical properties), or Excellent (a fully blown bottle with outstanding optical clarity).
  • Polypropylene bottles (500 ml, table XII) were produced at high speed (1 ,500 bottles/cavity/hour) on a Sidel SBO-8 Series-ll stretch blow molding machine designed to blow PET preforms using the polypropylene preforms described in Example 10.
  • Axial stretch ratio is 2.5/1
  • Hoop Stretch ratio 2.54
  • Total Stretch Ratio 6.36/1.
  • Machine settings were adjusted to accommodate high clarity, high speed bottle production.
  • Preforms were subjected to a pre- blow pressure of 4.5 Bar for 0.4 seconds & nozzle for 3 rotations open activated at 'point zero'. Blowing time is 0.8 sec & Exhaust time is 0.4 sec.
  • Stretch speed is 1 ,384 m/sec & a standard stretch rod with 14 mm diameter was used.
  • Preform temperature is about 120-130°C.
  • %GP 65 %.
  • Bottle quality was judged at the time of production to be Unacceptable (poorly blown bottle or blown out), Acceptable (a fully blown bottle with moderate optical properties), Average (a fully blown bottle with improved optical properties), or Excellent (a fully blown bottle with outstanding optical clarity).
  • Polypropylene bottles (500 ml) having a narrow neck were produced at high speed (1500 bottles/cavity/hour) on a Sidel SBO-8 Series-ll stretch blow molding machine designed to blow PET preforms using the polypropylene preforms described in Example 13.
  • the following stretch ratios were used: axial stretch ratio of 2.63/1 , radial stretch ratio of 3.08 and a total stretch ratio of 8.10/1.
  • Machine settings were adjusted to accommodate high clarity, high speed bottle production.
  • the temperature measured at the outer side of the preform was 143.5 °C and 152.5 "C at the inner side of the preform.
  • Bottle quality was judged at the time of production to be Unacceptable (poorly blown bottle or blown out), Acceptable (a fully blown bottle with moderate optical properties), Average (a fully blown bottle with improved optical properties), or Excellent (a fully blown bottle with outstanding optical clarity).
  • Thickness For purposes of this specification, the thickness of preforms is measured along the side walls 101 , 104 as shown in Figure 4A, measured at the widest portion of the side walls 101 ,104. Thickness of containers (bottles), such as for purposes of percent haze/thickness ratios is measured at the point at which the haze has been measured (see below), using a Magna-Mike 8500 Hall effect thickness gauge.
  • Gardner hazemeter by ASTM Standard Test Method D1003-61 modified by use of an 0.2" aperture.
  • the area in which haze could be measured reliably was in relatively small areas less than about 0.5" in area.
  • Samples were obtained from sample containers (bottles) at a relatively flat point approximately mid-way to the bottom of the bottle after the transition point.
  • a thickness modified haze was calculated for each sample where (H/t) is defined as the haze divided by the thickness at the point where the haze was measured. Roughness on the inner container 10 surface has a negative influence on the container clarity.
  • the material undesirably may be ruptured apart during the stretch blow molding (stage two) process, resulting in a rough inner container 10 surface and containers 10 having low clarity.
  • Example 15 Fill Rates and Gate Diameter Preforms were made with fill rates ranging from 5.5 to 40.2 grams per second utilizing two different resins - Borealis RF365MO (20 Ml RCP) and Atofina 7525 (12 Ml RCP). Three different injection valve gates were utilized in the preform production - 1.5, 3.0, and 3.8 mm.
  • Percent Production Power controls the temperature of the preform. Preblow is the time at which preblow begins with respect to the beginning of engagement of the stretch rod to the bottom of the preform.
  • Figure 12 is also illustrative of the effect of pre-blow time and pressure on container percent (%) haze.
  • Pre-blow pressure 1 bar (very hazy in panel) 2 bar (slightly hazy in panel) 4 bar (clear) 5 bar (clear) 7 bar (clear) 10 bar (clear).
  • Pre-blow time 0 sec (very hazy in panel) 0.05 sec (slightly hazy in panel) 0.1 sec (slightly hazy) 0.2 sec (clear) 0.4 sec (OK) 0.8 sec (OK)
  • Example 17 Free Shrinkage Data and Correlations
  • a polypropylene container is made by an injection stretch blow molding two stage process.
  • the container has: a) a side wall providing a haze value of less than 3 according to ASTM D 1003, b) an MFI (melt flow index) between about 6 g/10min and about 50 g/10min according to ASTM D 1238; c) wherein the average wall thickness of the container after subjecting the container to the free shrinkage test is less than about 1.8 mm.
  • a clear bottle may be produced by two stages, injection molding into a preform and then stretch blow the preform into the final clear bottle. Such bottles exhibit a certain percentage of free shrinkage in the axial direction. This is known as a “free shrinkage test” or “shrinkage test”, for purposes of this specification and claims.
  • the average length and wall thickness of the shrunk bottle can be used for calculations for shrinkage ratio or drawing conclusions.
  • Four types of the ISBM polypropylene bottles were used for this study, the first three examples (A, B, C) were made from the preforms based on the current inventive design, while the last one (D) is a comparative example based on prior art. Results of the shrinkage test are reported in Table XVI. Please note that preform dimensions are out of the preform design, length of the ISBM bottle is also out of design. While the thickness of the ISBM bottle, the length and thickness of the shrunk bottle were measured according to the above procedures. Numbers in the Table XVI below include measurements which are average numbers based on several measurements. Table XVI Results of the Free Shrinkage Study of ISBM Bottles
  • Sample D the comparative example bottle apparently exhibits the highest shrinkage ratio among all tested. It also has the highest wall thickness among all bottles tested.
  • wall thickness of the preform is one of the critical factors to make good quality and clear ISBM polypropylene bottles with good productivity.
  • the current invention designs the preform with the wall thickness of 3.5 mm or less, while the prior art is above that.
  • the comparative bottle has the wall thickness of 4.9 mm, while the first three bottles out of this invention have the wall thickness of 2.8 mm and 3.5 mm.
  • it is difficult to shrink the ISBM bottle completely back to the preform size the shrinkage behavior is similar provided all bottles are made of polypropylene random copolymer.
  • the wall thickness of the shrunk bottle relates closely to the preform wall thickness.
  • the comparable example bottle has the highest shrunk bottle wall thickness, largely due to the fact that the preform is high in wall thickness. This would be one way of differentiating the bottles based on the current inventive preform design or a prior art preform design.

Abstract

L'invention concerne un procédé de production, en deux étapes, d'articles de type contenants en polypropylène, transparents, à faible opacité, moulés par injection-soufflage avec bi-étirage, présentant des caractéristiques de retrait libre avantageuses. Au cours d'une première étape de traitement, une préforme est produite sur une presse d'injection. Au cours d'une deuxième étape, pouvant être réalisée à distance de l'appareil utilisé lors de la première étape, la préforme est chauffée et est soumise à un soufflage avec étirage pour former un contenant. Ce procédé peut comprendre une étape consistant à réaliser des préformes facilitant le soufflage avec étirage à des cadences relativement élevées, tout en maintenant une morphologie du polypropylène appropriée, ce qui permet d'obtenir des contenants transparents, à faible opacité. Le retrait libre peut être amélioré et mesuré. En outre, des paramètres tels que l'opacité, l'indice de fluidité à chaud et l'épaisseur de paroi des contenants soumis à un test de retrait libre, une fois produits, peuvent être utilisés pour estimer ou prédire les paramètres de traitement intervenant dans la production des contenants.
EP05754304A 2004-05-28 2005-05-26 Contenant en polyolefine presentant des caracteristiques de retrait determinees et procede pour produire de tels contenants Withdrawn EP1748931A4 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US57544704P 2004-05-28 2004-05-28
US11/137,046 US20050249905A1 (en) 2004-01-23 2005-05-25 Polyolefin container having certain shrink characteristics and method of making such containers
PCT/US2005/018522 WO2005118407A2 (fr) 2004-05-28 2005-05-26 Contenant en polyolefine presentant des caracteristiques de retrait determinees et procede pour produire de tels contenants

Publications (2)

Publication Number Publication Date
EP1748931A2 true EP1748931A2 (fr) 2007-02-07
EP1748931A4 EP1748931A4 (fr) 2007-06-27

Family

ID=35463411

Family Applications (1)

Application Number Title Priority Date Filing Date
EP05754304A Withdrawn EP1748931A4 (fr) 2004-05-28 2005-05-26 Contenant en polyolefine presentant des caracteristiques de retrait determinees et procede pour produire de tels contenants

Country Status (4)

Country Link
US (1) US20050249905A1 (fr)
EP (1) EP1748931A4 (fr)
BR (1) BRPI0511638A (fr)
WO (1) WO2005118407A2 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1870225A1 (fr) * 2006-06-21 2007-12-26 Total Petrochemicals Research Feluy Conditions d'étirage et de soufflage dans un procédé de moulage par étirage-soufflage
US11873133B2 (en) * 2021-04-20 2024-01-16 Drug Plastics & Glass Company, Inc. Bottle, injection blow molding core rod for the bottle and related method

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0151741A2 (fr) * 1983-12-13 1985-08-21 MITSUI TOATSU CHEMICALS, Inc. Récipient moulé par soufflage et composition de résine pour sa fabrication
US6129961A (en) * 1998-08-27 2000-10-10 Toyo Boseki Kabushiki Kaisha Polyester resin and production method thereof

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2717365A1 (de) * 1977-04-20 1978-10-26 Bekum Maschf Gmbh Verfahren zur herstellung von hohlkoerpern aus thermoplastischem kunststoff
US4357288A (en) * 1980-02-25 1982-11-02 Deacon Machinery, Inc. Method of making clear transparent polypropylene containers
EP0387737B1 (fr) * 1989-03-14 1993-08-11 BEKUM Maschinenfabriken GmbH Procédé pour réchauffer des préformes injectées prélevées d'une réserve, pour les souffler enfin dans un moule de soufflage et en faire des corps creux et procédé pour le moulage par soufflage de préformes préfabriquées
US5135975A (en) * 1989-09-20 1992-08-04 Milliken Research Corporation Bis(3,4-dialkylbenzylidene) sorbitol acetals and compositions containing same
DE4212248C2 (de) * 1992-04-11 1996-01-25 Bekum Maschf Gmbh Verfahren und Vorrichtung zur Erhitzung von, einem Vorrat entnommenen, im Spritzverfahren hergestellten Vorformlingen aus teilkristallinen Kunststoffen
EP0846544A1 (fr) * 1996-12-03 1998-06-10 BEKUM Maschinenfabriken GmbH Machine de moulage par soufflage avec dispositif de transport pour aussi changer l'écartement entre les préformes
US6627278B1 (en) * 1998-11-30 2003-09-30 Fort James Corporation Injection blow-molded disposable tumbler and method of making same

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0151741A2 (fr) * 1983-12-13 1985-08-21 MITSUI TOATSU CHEMICALS, Inc. Récipient moulé par soufflage et composition de résine pour sa fabrication
US6129961A (en) * 1998-08-27 2000-10-10 Toyo Boseki Kabushiki Kaisha Polyester resin and production method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO2005118407A2 *

Also Published As

Publication number Publication date
WO2005118407A3 (fr) 2007-03-01
EP1748931A4 (fr) 2007-06-27
US20050249905A1 (en) 2005-11-10
WO2005118407A2 (fr) 2005-12-15
BRPI0511638A (pt) 2008-01-02

Similar Documents

Publication Publication Date Title
EP1722957A2 (fr) Procede de fabrication en deux etapes d'articles en polypropylene moules par un moulage par injection et par soufflage bioriente
US20050249904A1 (en) Articles and process of making polypropylene articles having ultraviolet light protection by injection stretch blow molding of polypropylene
US4357288A (en) Method of making clear transparent polypropylene containers
CA2593927C (fr) Procede de formation de recipient par moulage par soufflage avec etirage, et recipient ainsi forme
RU2060889C1 (ru) Способ инжекционного ориентационного выдувного формования
RU2520564C2 (ru) Полимерная композиция и способ получения пластмассовых бутылок в двухстадийном процессе инжекционно-раздувного формования
US8691140B2 (en) Process for injection molding of thin-walled preform
US5840350A (en) Modified plastic bottle injection blow-molding apparatus and method
US4065535A (en) Thread forming and neck finishing process
WO2006031557A2 (fr) Preforme polymere pour article en plastique moule par soufflage
US4382769A (en) Container forming apparatus
EP0251340B1 (fr) Procédé de moulage par injection-soufflage
JPH01154723A (ja) ランダム共重合体ポリプロピレン容器とその製造法
CA1240446A (fr) Produit de moulage souffle-dilate, et composition de resine servant a sa fabrication
GB2124543A (en) Parison for oriented plastic containers
WO2005118407A2 (fr) Contenant en polyolefine presentant des caracteristiques de retrait determinees et procede pour produire de tels contenants
EP0241040A1 (fr) Fabrication de bouteilles en plastique
EP2032332B1 (fr) Conditions d'étirage-soufflage dans un moulage par injection avec étirage-soufflage en une étape
JP3578157B2 (ja) ブロー成形用予備成形物を圧縮成形するための圧縮成形装置
CA2980557C (fr) Contenant et procede de fabrication
US4442063A (en) Container forming process
CA2855150C (fr) Recipient forme par l'intermediaire d'un moulage par soufflage pluriel
CA1153522A (fr) Ensemble moule-noyau de paraison
KR20030074579A (ko) 이축연신 블로우 성형을 위한 예비성형물 및 예비성형물의제조방법
JPH0948061A (ja) 透明な底部を有するポリプロピレン２軸延伸ブローボトル

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20061127

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU MC NL PL PT RO SE SI SK TR

AX Request for extension of the european patent

Extension state: AL BA HR LV MK YU

PUAK Availability of information related to the publication of the international search report

Free format text: ORIGINAL CODE: 0009015

A4 Supplementary search report drawn up and despatched

Effective date: 20070529

RIN1 Information on inventor provided before grant (corrected)

Inventor name: LAMBERT, W. SCOTT

Inventor name: VEERMEERSCH, BERNARD

Inventor name: XU, JIANNONG

DAX Request for extension of the european patent (deleted)
17Q First examination report despatched

Effective date: 20070910

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

RIN1 Information on inventor provided before grant (corrected)

Inventor name: LAMBERT, W. SCOTT

Inventor name: VEERMEERSCH, BERNARD

Inventor name: XU, JIANNONG

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20090814