WO2006095952A1 - Apparatus and method to form starch bowl using mold having vent hole - Google Patents

Apparatus and method to form starch bowl using mold having vent hole Download PDF

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Publication number
WO2006095952A1
WO2006095952A1 PCT/KR2005/004264 KR2005004264W WO2006095952A1 WO 2006095952 A1 WO2006095952 A1 WO 2006095952A1 KR 2005004264 W KR2005004264 W KR 2005004264W WO 2006095952 A1 WO2006095952 A1 WO 2006095952A1
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WO
WIPO (PCT)
Prior art keywords
mold
bowl
vent hole
surface area
starch
Prior art date
Application number
PCT/KR2005/004264
Other languages
French (fr)
Inventor
Young-Hee Kim
Heon-Moo Kim
Kang-Soo Kim
Sung Hwan Yoon
Jun-Seung An
Yun-Mi Bang
Original Assignee
Youl Chon Chemical Co., Ltd.
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 Youl Chon Chemical Co., Ltd. filed Critical Youl Chon Chemical Co., Ltd.
Publication of WO2006095952A1 publication Critical patent/WO2006095952A1/en

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Classifications

    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21JFIBREBOARD; MANUFACTURE OF ARTICLES FROM CELLULOSIC FIBROUS SUSPENSIONS OR FROM PAPIER-MACHE
    • D21J3/00Manufacture of articles by pressing wet fibre pulp, or papier-mâché, between moulds
    • AHUMAN NECESSITIES
    • A47FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47GHOUSEHOLD OR TABLE EQUIPMENT
    • A47G1/00Mirrors; Picture frames or the like, e.g. provided with heating, lighting or ventilating means
    • A47G1/02Mirrors used as equipment
    • A47G1/04Multi-part mirrors
    • AHUMAN NECESSITIES
    • A45HAND OR TRAVELLING ARTICLES
    • A45DHAIRDRESSING OR SHAVING EQUIPMENT; EQUIPMENT FOR COSMETICS OR COSMETIC TREATMENTS, e.g. FOR MANICURING OR PEDICURING
    • A45D24/00Hair combs for care of the hair; Accessories therefor
    • A45D24/02Single-piece combs

Definitions

  • the present invention relates to an apparatus and a method to form starch bowl using mold having vent hole.
  • the present invention relates to an apparatus and a method to form starch bowl, wherein a composition for starch bowl can be uniformly foamed by using a mold having vent holes to improve a molding property of the starch bowl and reduce a defective proportion of the starch bowl, and further a coating film is formed on the surface of the mold to improve a releasing property of the starch bowl.
  • “residue of foaming composition for starch bowl” means a composition for starch bowl which is remained without being molded to the starch bowl during the process that the composition for starch bowl is foamed to be the complete starch bowl when molding.
  • bowl lip part of mold means a part of the mold for forming the lip of the bowl corresponding to contact portions between an upper mold and a lower mold and being on the upper mold and/or the lower mold.
  • the starch bowl is manufactured by inputting a composition for starch bowl into a mold and heating and pressurizing the composition.
  • FlG. 1 is a perspective view illustrating a conventional mold.
  • a mold for forming starch bowl 1 generally includes an upper mold 2 and a lower mold 3, wherein the upper mold 2 is moved up and down and the lower mold 3 is fixed.
  • the starch bowl has a poor releasing property, which decreases its production efficiency. That is, the starch bowl is not easily released from the mold after molding process and to this end, there is such disadvantage that the process should be stopped to manually detach the starch bowl from the mold piece by piece, which results in the decrease of the production efficiency. Further, there is alos a problem that a product defective occurs during the releasing process of the bowl from the mold.
  • the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an apparatus and a method to form a starch bowl wherein the molding property is excellent, uniform foaming of the composition is possible and the defective proportion of product can be decreased.
  • Another object of the present invention is to provide an apparatus and a method to form a starch bowl wherein the releasing property can be obtained effectively during the molding process of the starch bowl.
  • an apparatus to form a starch bowl comprising a mold to form the starch bowl composed of an upper mold moving up and down and a fixed lower mold, wherein the upper mold and/or the lower mold is provided with vent hole for discharging a gas generated when the composition for starch bowl is heated and pressurized during its molding process or a residue of foaming composition for starch bowl.
  • the vent hole is formed on a contact portion of the upper mold at which the upper mold comes in contact with the lower mold and/or a contact portion of the lower mold at which the lower mold comes in contact with the upper mold.
  • a ratio of a total sum of the surface area of the vent hole outlet to a surface area of the bowl lip part of mold is 1-2%.
  • the total sum of the surface area of the vent hole outlet is 18-24 mm . More preferably, 18-24 vent holes having the same shape, the surface area of the vent hole outlet being 1 mm , is formed.
  • a coating film is formed on a surface of the mold to provide a releasing property. More preferably, the coating film is made of a composite of organic and inorganic materials.
  • a method to form a starch bowl comprising the step of discharging a gas which is generated when the composition for starch bowl is molded or a residue of foaming composition for starch bowl during the process of molding.
  • the mold itself is provided with vent hole for discharging the gas or the residue of foaming composition for starch bowl.
  • the mold includes an upper mold moving up and down and a fixed lower mold, wherein the vent hole is formed on a contact portion of the upper mold at which the upper mold comes in contact with the lower mold and/or a contact portion of the lower mold at which the lower mold comes in contact with the upper mold.
  • a ratio of a total sum of the surface area of the vent hole outlet to a surface area of the bowl lip part of mold is regulated to control the discharging amount of the gas or the residue of foaming composition for starch bowl.
  • the regulation of the total sum of the surface area of the vent hole outlet is performed by controlling the number of the vent holes under the condition that the respective surface area of the vent hole outlet is set to be identical.
  • a coating film is formed on a surface of the mold to provide a releasing property. More preferably, the coating film is made of a composite of organic and inorganic materials.
  • the molding property of the starch bowl is excellent, the defective proportion of product can be decreased.
  • the prepared starch bowl can be easily detached from the mold after molding.
  • FIG. 1 is a perspective view illustrating a conventional mold.
  • FIG. 2 is a perspective view illustrating a mold according to an example of the present invention.
  • FIG. 3 is an enlarged perspective view illustrating the bowl lip part of mold in FIG.
  • FIG. 4 is a perspective view illustrating the state in which a gas and a residue of foaming composition for starch bowl are discharged from the mold through the vent holes when the composition for starch bowl is molded by using the mold according to an example of the present invention.
  • FIG. 5 is a cross-sectional perspective view illustrating an inner surface of the mold in FIG. 2 on which a coating film is formed to increase a releasing property.
  • FlG. 2 is a perspective view illustrating a mold according to an example of the present invention.
  • FlG. 3 is an enlarged perspective view illustrating the bowl lip part of mold in FlG. 2.
  • the mold 10 according to an example of the present invention comprises an upper mold 20 moving up and down and a fixed lower mold 30.
  • the contact portion 31 at which the lower mold 30 comes in contact with the upper mold 20 is provided with vent holes 35 for discharging a gas generated during the molding process of heating and pressurizing the composition for starch bowl or a residue of foaming composition for starch bowl.
  • FlG. 2 shows only the case wherein the vent holes 35 are disposed along with the contact portion 31 of the lower mold 30.
  • the vent holes may be formed on the upper mold 20 and/or the lower mold 30 (preferably, on the contact portions at which the lower mold comes in contact with the upper mold) to control the discharge of the gas or the residue of foaming composition for starch bowl.
  • vent hole 31 is not limited to that shown in FlGs. 2 and 3.
  • the entire shape of the vent hole or the surface shape of the vent hole outlet may be made in various shapes such as a triangular shape, a circular shape, a trapezoidal shape or the like.
  • the apparatus and method to form the starch bowl it is important to regulate the total sum of the surface area of the vent hole outlet. That is, the total sum of the surface area of the vent hole outlet 36 to the surface area of the bowl lip part of mold 38 should be regulated in order to obtain the good molding property, the uniform foamability and the good workability and reduce the defective proportion of product.
  • a ratio of the total sum of the surface area of the vent hole outlet 36 to the surface area of the bowl lip part of mold 38, in which the vent holes are formed is preferably 1-2%. If the ratio is less than 1%, foaming may not be sufficiently achieved, burst may occur due to the increased inner pressure and the defective proportion may be increased due to such molding defective. If the ratio is more than 2%, the molding property of the bowl and the uniformity of foamed cells may be decreased and a dry time may be prolonged, which result in the decrease of the workability.
  • vent hole outlet 36 in case that the total sum of the surface area of the vent hole outlet 36 to the surface area of the bowl lip part of mold 38 is regulated, it is perferable to form a plurality of vent holes respectively having the same outlet surface area and to regulate the number of the vent holes in order to achieve the uniform foaming with ease.
  • the ratio of the total sum of the surface area of the vent hole outlet 36 to the surface area of the bowl lip part of mold 38 may be set to the following, for example. That is, in case that the surface area of the bowl lip part of mold 38 is 1400 mm 2 , if the total sum of the surface area of the vent hole outlet 36 is set to 18-24 mm , the ratio of the surface area can be set to be about 1-2%.
  • 18-24 vent holes having the same shape, of which the outlet surface area 36 is 1 mm are formed since the uniform foaming and regulation of the inner pressure become possible.
  • FlG. 4 is a perspective view illustrating the state in which a gas and a residue of foaming composition for starch bowl are discharged from the mold through the vent holes when the composition for starch bowl is molded by using the mold according to an example of the present invention.
  • the discharge of the gas or the residue of foaming composition for starch bowl can be regulated by forming the vent holes on the mold during the molding process, thereby improving the molding property of the starch bowl and reducing the defective proportion of product.
  • a coating film is formed on the surface of the mold so as to easily release the starch bowl from the mold.
  • FlG. 5 is a cross-sectional perspective view illustrating an inner surface of the mold in FlG. 2 on which a coating film is formed to increase a releasing property.
  • the coating film 39 is formed on the inner part 37 of the lower mold 30 having the vent holes 35.
  • FlG. 5 shows only the inner surface of the lower mold 30 as an example, the coating film can also be formed on the inner surface of both upper mold and lower mold as well as the inner surface of the upper mold.
  • the coating film makes the separation of the prepared bowl from the mold easy.
  • the coating film is formed on the mold, the molding property of the bowl becomes excellent since the composition for starch bowl becomes to have a good flow property in the inner part of the coated mold due to the decrease of surface tension during the molding process of heating and presurizing the composition in the mold.
  • the coating film can be fomred for example by applying Teflon (organic material coating), by forming an oxide film (inorganic material coating), or by forming a coating film made of a composite of the organic and inorganic materials.
  • Teflon (trademark of Dupont for tetrafluorocarbon resin) shows excellent chemically inert property, heat resistance, non-sticking property, insulation stability and low friction coefficient etc. by producung a very stable compound through the strong chemical bond of the fluorine and carbon.
  • Teflon is liquidated and spray-coated on the inner surface of the mold, and then heated at a desired temperature so as to form a rigid coating film.
  • Said formation of the oxide film (anodizing) is generally called as an anodic oxidation method.
  • electric current is applied to the mold to generate oxygen so that the oxygen oxidizes the surface of the mold to form a thin film. Since the thin film has high strength and superior corrosion resistance as well as a very small porous property, there is such merit that the thin film can be dyed in various colors.
  • Said coating method of the organic material and said coating method of the inorganic material may be combinated for the coating film made of the composite of the organic and inorganic materials.
  • an organic material having excellent lubrication, releasing property and insulating property such as fluorine-based resin (fluorocarbon resin), siloxane- based resin or other super engineering plastics [or specialty engineering plastics; high performance plastics suitable for members of construction or machinery, which can be used for a long time even at high temperature, and having tensile strength of more than 500 kgf/cm (49MPa), modulus of bending elasticity of more than 20,000 kgf/cm (2GPa) and heat resistance of more than 150°C] is mixed with an inorganic material such as ceramic or metal and then is coated to the mold, or alternatively is used together when coating a high hard inorganic film such as conversion coating film, thereby forming the coating film made of the composite of the organic and inorganic materials.
  • fluorine-based resin fluorocarbon resin
  • siloxane- based resin or other super engineering plastics or specialty engineering plastics; high performance plastics suitable for members of construction or machinery, which can be used for a long time even at high
  • the coating film made of the composite of the organic and inorganic materials provides the lubrication, non-sticking property, corrosion resistance, oil resistance and water resistance under conditions requiring for superior wear resistance and heat resistance which cannot be obtained by only the conventional organic coating or the inorganic coating. Therefore, such coating film is particularly effective to form the coating film onto the upper mold and the lower mold in the present invention.
  • Example 1 of Experiment 1 an oxide film (Example 2 of Experiment 2) and a film made of the composite of the organic and inorganic materials (used was "BICOAT” of Yoshida SKT Co., LTD, Japan) (Example 3 of Experiment 1). 100 molded products were made from each mold.
  • the leakage test was carried out by leaving the bowl into which a test solution was poured for 20 minutes at a room temperature and identifying with the naked eye whether a red fluid was leaked from the bowl.
  • the test solution was prepared by mixing a red ink, a surfactant and water. The leakage can be easily identified by detecting the leakage of red fluid from the white or pale yellow bowl.
  • Table 1 shows the result of the test in which 100 starch bowls were made by inputting the composition for starch bowl in the mold coated by the methods set forth in each example of Experiment 1.
  • sticking on the upper mold means that the bowl is not detached from the upper mold and thus is forcibly released from the upper mold by hand or tool when the upper mold is separated from the fixed lower mold after the composition for starch bowl is foamed.
  • occurrence of pin hole phenomena means that a hole is made on the laminated surface in case that a film having a thickness of 180 D, which is heated at a temperature of 130 °C, is laminated to the prepared bowl under conditions of a vacuum time of 1.5 seconds and a vacuum pressure of 0.1 MPa.
  • Example 1 forming Teflon coating shows the releasing property simlar to that of Example 3, there was a major drawback that the Teflon coating was peeled off from the mold in several tests.
  • composition for starch bowl prepared by mixing starch, pulp, water and typical additives was input into the heating and pressurizing lower mold heated to 180°C and was covered by the upper mold, and then molded for 130 seconds under the pressure of
  • the lower mold was provided with vent holes serving as the passage for discharging the gas or the residue of foaming composition for starch bowl, the residue not being molded to the starch bowl, on its upper girth part which is the contact portion of the lower mold among the conatact portions at which the lower mold comes in contact with the upper mold.
  • the composition for starch bowl was foamed with the lower mold, the lower mold being provided with 18 vent holes each having the same size and shape and outlet surface area of each vent hole being 1 mm (width) x 1 mm (height) samely for all the vent holes. Meanwhile, the upper and lower molds were coated with "BICOAT" (available from Yoshida SKT Co., LTD, Japan) so as to form the coating film made of the composite of the organic and inorganic materials.
  • the composition for starch bowl was foamed with the lower mold, the lower mold being provided with 24 vent holes each having the same size and shape and outlet surface area of each vent hole being 1 mm (width) x 1 mm (height) samely for all the vent holes.
  • the same method as Example 1 was performed for the other conditions.
  • composition for starch bowl was foamed with the lower mold, the lower mold not being provided with any vent hole.
  • the same method as Example 1 was performed for the other conditions.
  • the composition for starch bowl was foamed with the lower mold, the lower mold being provided with 12 vent holes each having the same size and shape and outlet surface area of each vent hole being 1 mm (width) x 1 mm (height) samely for all the vent holes.
  • the same method as Example 1 was performed for the other conditions.
  • the composition for starch bowl was foamed with the lower mold, the lower mold being provided with 30 vent holes each having the same size and shape and outlet surface area of each vent hole being 1 mm (width) x 1 mm (height) samely for all the vent holes.
  • the same method as Example 1 was performed for the other conditions.
  • the composition for starch bowl was foamed with the lower mold, the lower mold being provided with 18 vent holes each having the same size and shape and outlet surface area of each vent hole being 0.5 mm (width) x 1 mm (height) samely for all the vent holes.
  • the same method as Example 1 was performed for the other conditions.
  • the composition for starch bowl was foamed with the lower mold, the lower mold being provided with 18 vent holes each having the same size and shape and outlet surface area of each vent hole being 3 mm (width) x 1 mm (height) samely for all the vent holes.
  • the same method as Example 1 was performed for the other conditions.
  • the composition for starch bowl was foamed with the lower mold, the lower mold being provided with 18 vent holes each having the same size and shape and outlet surface area of each vent hole being 5 mm (width) x 1 mm (height) samely for all the vent holes.
  • the same method as Example 1 was performed for the other conditions.
  • Table 2 shows the size and numbers of the vent holes in Examples 1, 2 and Comparative Examples 1-6 of Experiment 2. [86] Table 2
  • Molding property of bowl [89] ® indicates that the surface is smooth and has no crease or pin hole, O indicates that the surface is rough relatively but has no crease or pin hole, and X indicates that the surface has creases or pin holes and to this end it is difficult to be used for a product.
  • the present invention is related to an apparatus and a method for forming a starch bowl, wherein, by using a mold having vent holes, a composition for starch bowl can be uniformly foamed to improve the molding property of the starch bowl and reduce the defective proportion, and further a coating film is formed on the surface of the mold to improve the releasing property.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

Disclosed are an apparatus and a method to form a starch bowl using mold having vent hole for discharging a gas or a residue of foaming composition for starch bowl during the molding process. According to the present invention, the molding property of the starch bowl is excellent, the defective proportion of product can be decreased. In addition, the prepared starch bowl can be easily detached from the mold after molding.

Description

Description
APPARATUS AND METHOD TO FORM STARCH BOWL USING MOLD HAVING VENT HOLE
Technical Field
[1] The present invention relates to an apparatus and a method to form starch bowl using mold having vent hole. In particular, the present invention relates to an apparatus and a method to form starch bowl, wherein a composition for starch bowl can be uniformly foamed by using a mold having vent holes to improve a molding property of the starch bowl and reduce a defective proportion of the starch bowl, and further a coating film is formed on the surface of the mold to improve a releasing property of the starch bowl.
Background Art
[2] In this specification, "residue of foaming composition for starch bowl" means a composition for starch bowl which is remained without being molded to the starch bowl during the process that the composition for starch bowl is foamed to be the complete starch bowl when molding.
[3] In this specification, "bowl lip part of mold" means a part of the mold for forming the lip of the bowl corresponding to contact portions between an upper mold and a lower mold and being on the upper mold and/or the lower mold.
[4] The starch bowl is manufactured by inputting a composition for starch bowl into a mold and heating and pressurizing the composition.
[5] FlG. 1 is a perspective view illustrating a conventional mold. As shown in FlG. 1, a mold for forming starch bowl 1 generally includes an upper mold 2 and a lower mold 3, wherein the upper mold 2 is moved up and down and the lower mold 3 is fixed.
[6] Further, after the composition for starch bowl is inputted into the lower mold 3, the upper mold 2 contacts closely with the lower mold 3, and the heating and pressurizing is performed to manufacture the starch bowl of a desired shape.
[7] In such a molding process, a gas such as water vapor is generated when the composition for starch bowl is foamed. Furthermore, although the most parts of the composition for starch bowl become molded to the bowl when heated and pressurized, some parts of the composition for starch bowl are remained without being molded to the bowl.
[8] In order to obtain a good molding property and reduce a defective proportion, such gas and residue of foaming composition for starch bowl should be discharged from the mold. However, since such gas and residue of foaming composition for starch bowl could not be discharged from the mold according to prior art, a pressure was increased in a constant volume so that the composition came to be excessively foamed or be burst without being molded to the shape of the bowl.
[9] Meanwhile, the starch bowl has a poor releasing property, which decreases its production efficiency. That is, the starch bowl is not easily released from the mold after molding process and to this end, there is such disadvantage that the process should be stopped to manually detach the starch bowl from the mold piece by piece, which results in the decrease of the production efficiency. Further, there is alos a problem that a product defective occurs during the releasing process of the bowl from the mold.
Disclosure of Invention Technical Problem
[10] Accordingly, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an apparatus and a method to form a starch bowl wherein the molding property is excellent, uniform foaming of the composition is possible and the defective proportion of product can be decreased.
[11] Another object of the present invention is to provide an apparatus and a method to form a starch bowl wherein the releasing property can be obtained effectively during the molding process of the starch bowl. Technical Solution
[12] In order to accomplish the above objects of the present invention, there is provided an apparatus to form a starch bowl comprising a mold to form the starch bowl composed of an upper mold moving up and down and a fixed lower mold, wherein the upper mold and/or the lower mold is provided with vent hole for discharging a gas generated when the composition for starch bowl is heated and pressurized during its molding process or a residue of foaming composition for starch bowl.
[13] Preferably, the vent hole is formed on a contact portion of the upper mold at which the upper mold comes in contact with the lower mold and/or a contact portion of the lower mold at which the lower mold comes in contact with the upper mold.
[14] Preferably, a ratio of a total sum of the surface area of the vent hole outlet to a surface area of the bowl lip part of mold is 1-2%.
[15] Preferably, in case that the surface area of the bowl lip part of mold is 1400 mm2, the total sum of the surface area of the vent hole outlet is 18-24 mm . More preferably, 18-24 vent holes having the same shape, the surface area of the vent hole outlet being 1 mm , is formed.
[16] Preferably, a coating film is formed on a surface of the mold to provide a releasing property. More preferably, the coating film is made of a composite of organic and inorganic materials.
[17] In order to accomplish the above objects of the present invention, there is provided a method to form a starch bowl comprising the step of discharging a gas which is generated when the composition for starch bowl is molded or a residue of foaming composition for starch bowl during the process of molding.
[18] Preferably, the mold itself is provided with vent hole for discharging the gas or the residue of foaming composition for starch bowl.
[19] Preferably, the mold includes an upper mold moving up and down and a fixed lower mold, wherein the vent hole is formed on a contact portion of the upper mold at which the upper mold comes in contact with the lower mold and/or a contact portion of the lower mold at which the lower mold comes in contact with the upper mold.
[20] Preferably, a ratio of a total sum of the surface area of the vent hole outlet to a surface area of the bowl lip part of mold is regulated to control the discharging amount of the gas or the residue of foaming composition for starch bowl. Further, preferably, the regulation of the total sum of the surface area of the vent hole outlet is performed by controlling the number of the vent holes under the condition that the respective surface area of the vent hole outlet is set to be identical.
[21] Preferably, a coating film is formed on a surface of the mold to provide a releasing property. More preferably, the coating film is made of a composite of organic and inorganic materials.
Advantageous Effects
[22] According to the present invention, the molding property of the starch bowl is excellent, the defective proportion of product can be decreased. In addition, the prepared starch bowl can be easily detached from the mold after molding.
Brief Description of the Drawings
[23] FIG. 1 is a perspective view illustrating a conventional mold.
[24] FIG. 2 is a perspective view illustrating a mold according to an example of the present invention. [25] FIG. 3 is an enlarged perspective view illustrating the bowl lip part of mold in FIG.
2. [26] FIG. 4 is a perspective view illustrating the state in which a gas and a residue of foaming composition for starch bowl are discharged from the mold through the vent holes when the composition for starch bowl is molded by using the mold according to an example of the present invention. [27] FIG. 5 is a cross-sectional perspective view illustrating an inner surface of the mold in FIG. 2 on which a coating film is formed to increase a releasing property.
Best Mode for Carrying Out the Invention [28] Hereinafter, an apparatus and a method to form a starch bowl using mold having vent hole according to the present invention will be described in detail.
[29] FlG. 2 is a perspective view illustrating a mold according to an example of the present invention. FlG. 3 is an enlarged perspective view illustrating the bowl lip part of mold in FlG. 2.
[30] As shown in FlG. 2, the mold 10 according to an example of the present invention comprises an upper mold 20 moving up and down and a fixed lower mold 30. The contact portion 31 at which the lower mold 30 comes in contact with the upper mold 20 is provided with vent holes 35 for discharging a gas generated during the molding process of heating and pressurizing the composition for starch bowl or a residue of foaming composition for starch bowl.
[31] FlG. 2 shows only the case wherein the vent holes 35 are disposed along with the contact portion 31 of the lower mold 30. The vent holes, however, may be formed on the upper mold 20 and/or the lower mold 30 (preferably, on the contact portions at which the lower mold comes in contact with the upper mold) to control the discharge of the gas or the residue of foaming composition for starch bowl.
[32] Further, the shape of the vent hole 31 is not limited to that shown in FlGs. 2 and 3.
The entire shape of the vent hole or the surface shape of the vent hole outlet may be made in various shapes such as a triangular shape, a circular shape, a trapezoidal shape or the like.
[33] In the apparatus and method to form the starch bowl, it is important to regulate the total sum of the surface area of the vent hole outlet. That is, the total sum of the surface area of the vent hole outlet 36 to the surface area of the bowl lip part of mold 38 should be regulated in order to obtain the good molding property, the uniform foamability and the good workability and reduce the defective proportion of product.
[34] Herein, a ratio of the total sum of the surface area of the vent hole outlet 36 to the surface area of the bowl lip part of mold 38, in which the vent holes are formed, is preferably 1-2%. If the ratio is less than 1%, foaming may not be sufficiently achieved, burst may occur due to the increased inner pressure and the defective proportion may be increased due to such molding defective. If the ratio is more than 2%, the molding property of the bowl and the uniformity of foamed cells may be decreased and a dry time may be prolonged, which result in the decrease of the workability.
[35] Further, in case that the total sum of the surface area of the vent hole outlet 36 to the surface area of the bowl lip part of mold 38 is regulated, it is perferable to form a plurality of vent holes respectively having the same outlet surface area and to regulate the number of the vent holes in order to achieve the uniform foaming with ease.
[36] The ratio of the total sum of the surface area of the vent hole outlet 36 to the surface area of the bowl lip part of mold 38 may be set to the following, for example. That is, in case that the surface area of the bowl lip part of mold 38 is 1400 mm2, if the total sum of the surface area of the vent hole outlet 36 is set to 18-24 mm , the ratio of the surface area can be set to be about 1-2%. Herein, as described previously, it is preferable that 18-24 vent holes having the same shape, of which the outlet surface area 36 is 1 mm , are formed since the uniform foaming and regulation of the inner pressure become possible.
[37] FlG. 4 is a perspective view illustrating the state in which a gas and a residue of foaming composition for starch bowl are discharged from the mold through the vent holes when the composition for starch bowl is molded by using the mold according to an example of the present invention.
[38] As shown in FlG. 4, in the process of inputting the composition for starch bowl into the lower mold 30 having the vent holes 35 at the contact portion 31 and heating and pressurizng the composition to form the bowl 40 having a desired shape, the gas generated during the foaming or the residue of foaming composition for starch bowl 50 is discharged from the mold through a plurality of the vent holes 35.
[39] According to the present invention, the discharge of the gas or the residue of foaming composition for starch bowl can be regulated by forming the vent holes on the mold during the molding process, thereby improving the molding property of the starch bowl and reducing the defective proportion of product.
[40] Meanwhile, according to the present invention, a coating film is formed on the surface of the mold so as to easily release the starch bowl from the mold.
[41] FlG. 5 is a cross-sectional perspective view illustrating an inner surface of the mold in FlG. 2 on which a coating film is formed to increase a releasing property.
[42] As shown in FlG. 5, the coating film 39 is formed on the inner part 37 of the lower mold 30 having the vent holes 35. Though FlG. 5 shows only the inner surface of the lower mold 30 as an example, the coating film can also be formed on the inner surface of both upper mold and lower mold as well as the inner surface of the upper mold.
[43] The coating film makes the separation of the prepared bowl from the mold easy. In addition, in case that the coating film is formed on the mold, the molding property of the bowl becomes excellent since the composition for starch bowl becomes to have a good flow property in the inner part of the coated mold due to the decrease of surface tension during the molding process of heating and presurizing the composition in the mold.
[44] The coating film can be fomred for example by applying Teflon (organic material coating), by forming an oxide film (inorganic material coating), or by forming a coating film made of a composite of the organic and inorganic materials.
[45] Said Teflon (trademark of Dupont for tetrafluorocarbon resin) shows excellent chemically inert property, heat resistance, non-sticking property, insulation stability and low friction coefficient etc. by producung a very stable compound through the strong chemical bond of the fluorine and carbon. In coating, Teflon is liquidated and spray-coated on the inner surface of the mold, and then heated at a desired temperature so as to form a rigid coating film.
[46] Said formation of the oxide film (anodizing) is generally called as an anodic oxidation method. In the method, electric current is applied to the mold to generate oxygen so that the oxygen oxidizes the surface of the mold to form a thin film. Since the thin film has high strength and superior corrosion resistance as well as a very small porous property, there is such merit that the thin film can be dyed in various colors.
[47] Said coating method of the organic material and said coating method of the inorganic material may be combinated for the coating film made of the composite of the organic and inorganic materials.
[48] For example, an organic material having excellent lubrication, releasing property and insulating property, such as fluorine-based resin (fluorocarbon resin), siloxane- based resin or other super engineering plastics [or specialty engineering plastics; high performance plastics suitable for members of construction or machinery, which can be used for a long time even at high temperature, and having tensile strength of more than 500 kgf/cm (49MPa), modulus of bending elasticity of more than 20,000 kgf/cm (2GPa) and heat resistance of more than 150°C] is mixed with an inorganic material such as ceramic or metal and then is coated to the mold, or alternatively is used together when coating a high hard inorganic film such as conversion coating film, thereby forming the coating film made of the composite of the organic and inorganic materials.
[49] The coating film made of the composite of the organic and inorganic materials provides the lubrication, non-sticking property, corrosion resistance, oil resistance and water resistance under conditions requiring for superior wear resistance and heat resistance which cannot be obtained by only the conventional organic coating or the inorganic coating. Therefore, such coating film is particularly effective to form the coating film onto the upper mold and the lower mold in the present invention.
[50] Hereinafter, the present invention will be described further in detail by describing the preferred examples and experiments of the present invention. However, the present invention is not limited to the following examples, and various modification can be realized in the scope of the accompanying claims. The following examples are just for making those skilled in the art carry out the present invention with ease and the complete disclosure of the present invention.
[51] [Experiment 1 Evaluation of the releasing property etc. when the coating film is formed in the mold] [52] A molded product of a bowl shape was made by molding a composition for starch bowl composed of starch, pulp, water and typical additives in the prepared mold during 130 seconds under conditions that the mold had temperature of 180°C and pressure of 3 kgf/cm2.
[53] Prior to the molding, the upper mold and the lower mold were coated with a Teflon
(Example 1 of Experiment 1), an oxide film (Example 2 of Experiment 2) and a film made of the composite of the organic and inorganic materials (used was "BICOAT" of Yoshida SKT Co., LTD, Japan) (Example 3 of Experiment 1). 100 molded products were made from each mold.
[54] In order to evaluate the releasing property in each example of Experiment 1, it was observed whether the starch bowl was not released from the upper mod and was moved up with the uppert mold being sticking on the upper mold when the upper mold was separated from the fixed lower mold after the composition for starch bowl was molded in the mold during 130 seconds.
[55] Further, it was observed whether a pin hole was formed in the prepared bowl of each example of Experiment 1. In order to accurately observe such pin hole phenomena, a leakage test was carried out by laminating a film having a thickness of 180 D on the prepared bowl.
[56] The leakage test was carried out by leaving the bowl into which a test solution was poured for 20 minutes at a room temperature and identifying with the naked eye whether a red fluid was leaked from the bowl. The test solution was prepared by mixing a red ink, a surfactant and water. The leakage can be easily identified by detecting the leakage of red fluid from the white or pale yellow bowl.
[57] Table 1 shows the result of the test in which 100 starch bowls were made by inputting the composition for starch bowl in the mold coated by the methods set forth in each example of Experiment 1.
[58] Herein, "sticking on the upper mold" means that the bowl is not detached from the upper mold and thus is forcibly released from the upper mold by hand or tool when the upper mold is separated from the fixed lower mold after the composition for starch bowl is foamed.
[59] Further, "occurrence of pin hole phenomena" means that a hole is made on the laminated surface in case that a film having a thickness of 180 D, which is heated at a temperature of 130 °C, is laminated to the prepared bowl under conditions of a vacuum time of 1.5 seconds and a vacuum pressure of 0.1 MPa.
[60] Table 1
Figure imgf000009_0001
Figure imgf000010_0001
[61] As can be seen from Table 1, differences of the molding property and the releasing property according to the mold coating materials could be understood.
[62] First of all, in the Example 2 forming the oxide film, the phenomena "sticking on the upper mold" were clearly found out since the releasing property of the starch bowl was weak. Further, it could be identified by the naked eye that the surface of the bowl after foaming was not smooth and the pin hole phenomena occurred.
[63] In addition, although Example 1 forming Teflon coating shows the releasing property simlar to that of Example 3, there was a major drawback that the Teflon coating was peeled off from the mold in several tests.
[64] Therefore, it could be understood that the forming of the coating film made of the composite of the organic and inorganic materials in Example 3 was the most preferable among the mold coating methods for molding the composition for starch bowl.
[65] [Experiment 2 Test of the differences in the molding property etc. according to the surface area and number of the vent holes]
[66] In Experiment 2, after the surface area of the bowl lip part of lower mold with the vent holes was set to 1400 mm , the lower molds with different numbers and sizes of the vent holes were made in the respective examples (the total sum of the surface area of the vent hole outlet was 18-24 mm2) and comparative examples (the vent hole was not formed or the total sum of the surface area of the vent hole outlet was out of such range of the examples). The composition for starch bowl was foamed using each mold and 100 starch bowls were prepared.
[67] <Example 1 of Experiment 2>
[68] The composition for starch bowl prepared by mixing starch, pulp, water and typical additives was input into the heating and pressurizing lower mold heated to 180°C and was covered by the upper mold, and then molded for 130 seconds under the pressure of
3 kgf/cm to make 100 starch foamed bowls. [69] The lower mold was provided with vent holes serving as the passage for discharging the gas or the residue of foaming composition for starch bowl, the residue not being molded to the starch bowl, on its upper girth part which is the contact portion of the lower mold among the conatact portions at which the lower mold comes in contact with the upper mold. [70] The composition for starch bowl was foamed with the lower mold, the lower mold being provided with 18 vent holes each having the same size and shape and outlet surface area of each vent hole being 1 mm (width) x 1 mm (height) samely for all the vent holes. Meanwhile, the upper and lower molds were coated with "BICOAT" (available from Yoshida SKT Co., LTD, Japan) so as to form the coating film made of the composite of the organic and inorganic materials.
[71] <Example 2 of Experiment 2>
[72] The composition for starch bowl was foamed with the lower mold, the lower mold being provided with 24 vent holes each having the same size and shape and outlet surface area of each vent hole being 1 mm (width) x 1 mm (height) samely for all the vent holes. The same method as Example 1 was performed for the other conditions.
[73] <Comparative Example 1 of Experiment 2>
[74] The composition for starch bowl was foamed with the lower mold, the lower mold not being provided with any vent hole. The same method as Example 1 was performed for the other conditions.
[75] <Comparative Example 2 of Experiment 2>
[76] The composition for starch bowl was foamed with the lower mold, the lower mold being provided with 12 vent holes each having the same size and shape and outlet surface area of each vent hole being 1 mm (width) x 1 mm (height) samely for all the vent holes. The same method as Example 1 was performed for the other conditions.
[77] <Comparative Example 3 of Experiment 2>
[78] The composition for starch bowl was foamed with the lower mold, the lower mold being provided with 30 vent holes each having the same size and shape and outlet surface area of each vent hole being 1 mm (width) x 1 mm (height) samely for all the vent holes. The same method as Example 1 was performed for the other conditions.
[79] <Comparative Example 4 of Experiment 2>
[80] The composition for starch bowl was foamed with the lower mold, the lower mold being provided with 18 vent holes each having the same size and shape and outlet surface area of each vent hole being 0.5 mm (width) x 1 mm (height) samely for all the vent holes. The same method as Example 1 was performed for the other conditions.
[81] <Comparative Example 5 of Experiment 2>
[82] The composition for starch bowl was foamed with the lower mold, the lower mold being provided with 18 vent holes each having the same size and shape and outlet surface area of each vent hole being 3 mm (width) x 1 mm (height) samely for all the vent holes. The same method as Example 1 was performed for the other conditions.
[83] <Comparative Example 6 of Experiment 2>
[84] The composition for starch bowl was foamed with the lower mold, the lower mold being provided with 18 vent holes each having the same size and shape and outlet surface area of each vent hole being 5 mm (width) x 1 mm (height) samely for all the vent holes. The same method as Example 1 was performed for the other conditions.
[85] Table 2 shows the size and numbers of the vent holes in Examples 1, 2 and Comparative Examples 1-6 of Experiment 2. [86] Table 2
Figure imgf000012_0001
[87] In this experiment, the molding property, uniformity of foamed cells, defective proportion and dry time were measured for Examples 1, 2 and Comparative Examples 1-6.
[88] Molding property of bowl [89] ® indicates that the surface is smooth and has no crease or pin hole, O indicates that the surface is rough relatively but has no crease or pin hole, and X indicates that the surface has creases or pin holes and to this end it is difficult to be used for a product.
[90] Uniformity of foamed cells [91] The foamed starch bowl was cut with a shaft knife and was observed by an electron microscope so as to analyze whether the foamed cell was uniformly formed. In the result, "Uniform" indicates that the size of the foamed cell is uniform and constant. "Non-uniform" indicates that the size of the foamed cell is not uniform.
[92] Defective proportion [93] It was checked whether 100 starch bowls made by each mold had any defective. "Defective" indicates occurrence of any tear of the bowl, occurrence of any wavy pattern (crease), occurrence of any excess foaming, occurrence of a lot of pin holes or occurrence of any burst of bowl due to the increased innner pressure.
[94] Dry time [95] The time required to mold the composition to the starch bowl using the mold when a temperature (180°C) and a pressure (3 kgf/cm ) were constantly applied thereto. [96] Table 3 shows the measured results of the molding property, the uniformity of foamed cells, the defective proportion and the dry time. [97] Table 3
Figure imgf000013_0001
[98] As can be seen from Tables 2 and 3, in case that the surface area of the bowl lip part
2 of lower mold was 1400 mm , the number of vent holes formed on the lip part was
2
18-24 and the outlet surface area of each vent hole was 1 mm samely for all the vent holes, the molding property was excellent, the foamed cell was uniform and the defective proportion was decreased.
[99] Meanwhile, the molding property of the bowl became excellent as the size of vent holes was decreased. Further, the foaming ratio became excellent due to the suitable increase of the inner pressure in the inner part of the mold.
[100] However, in case that the ratio of the total sum of the surface area of the vent hole outlet to the surface area of the bowl lip part of mold is less than 1% as Comparative Examples 2 and 4, the burst occurred due to the increased inner pressure or the defective proportion was high due to the poor molding.
[101] In addition, in case that the mold had no vent hole (Comparative Example 1 of Experiment 2), the composition for starch bowl was excessively foamed or it was burst without forming the bowl shape due to the excessively increased inner pressure since the gas or the residue of foaming composition for starch bowlm, which should come out from the mold, could not be discharged from the mold.
[102] Furthermore, in case that the number of the vent holes became more than 25
(Comparative Example 3 of Experiment 2) or the surface area of the vent hole outlet was increased (Comparative Examples 5 and 6 of Experiment 2), the pressure in the mold was decreased and thus the composition for starch bowl was molded in a wet state, thereby increasing the dry time (increased to 150 seconds) and decreasing its workability.
[103] Therefore, in case that the surface area of the bowl lip part of lower mold is 1400 mm , if the number of vent holes having the surface area of 1 mm samely for all the vent holes is 18-24 or the total sum of the surface area of vent hole outlet is 18-24 mm
, which means that the ratio of the total sum of the surface area of the vent hole outlet to the surface area of the bowl lip part of mold is about 1-2%, the defective proportion was decreased, and the molding property and the formation of foamed layer was excellent.
Industrial Applicability
[104] The present invention is related to an apparatus and a method for forming a starch bowl, wherein, by using a mold having vent holes, a composition for starch bowl can be uniformly foamed to improve the molding property of the starch bowl and reduce the defective proportion, and further a coating film is formed on the surface of the mold to improve the releasing property.

Claims

Claims
[I] An apparatus to form a starch bowl comprising a mold to form the starch bowl composed of an upper mold moving up and down and a fixed lower mold, wherein the upper mold and/or the lower mold is provided with vent hole for discharging a gas generated when the composition for starch bowl is heated and pressurized during its molding process or a residue of foaming composition for starch bowl.
[2] The apparatus according to Claim 1, wherein the vent hole is formed on a contact portion of the upper mold at which the upper mold comes in contact with the lower mold and/or a contact portion of the lower mold at which the lower mold comes in contact with the upper mold. [3] The apparatus according to Claim 2, wherein a ratio of a total sum of the surface area of the vent hole outlet to a surface area of the bowl lip part of mold is 1-2%. [4] The apparatus according to Claim 3, wherein in case that the surface area of the bowl lip part of mold is 1400 mm2, the total sum of the surface area of the vent hole outlet is 18-24 mm . [5] The apparatus according to Claim 4, wherein 18-24 vent holes having the same shape, the surface area of the vent hole outlet being 1 mm , is formed. [6] The apparatus according to one of Claims 1 to 5, wherein a coating film is formed on a surface of the upper mold and/or the lower mold to provide a releasing property. [7] The apparatus according to Claim 6, wherein the coating film is made of a composite of organic and inorganic materials. [8] A method to form a starch bowl comprising the step of discharging a gas which is generated when the composition for starch bowl is molded or a residue of foaming composition for starch bowl during the process of molding. [9] The method according to Claim 8, wherein the mold itself is provided with vent hole for discharging the gas or the residue of foaming composition for starch bowl. [10] The method according to Claim 9, wherein the mold includes an upper mold moving up and down and a fixed lower mold and the vent hole is formed on a contact portion of the upper mold at which the upper mold comes in contact with the lower mold and/or a contact portion of the lower mold at which the lower mold comes in contact with the upper mold.
[II] The method according to Claim 10, wherein a ratio of a total sum of the surface area of the vent hole outlet to a surface area of the bowl lip part of mold is regulated to control the discharging amount of the gas or the residue of foaming composition for starch bowl. [12] The method according to Claim 11, wherein the regulation of the total sum of the surface area of the vent hole outlet is performed by controlling the number of the vent holes under the condition that the respective surface area of the vent hole outlet is set to be identical. [13] The method according to one of Claims 10 to 12, wherein a coating film is formed on a surface of the upper mold and/or the lower mold to provide a releasing property. [14] The method according to Claim 13, wherein the coating film is made of a composite of organic and inorganic materials.
PCT/KR2005/004264 2005-03-07 2005-12-13 Apparatus and method to form starch bowl using mold having vent hole WO2006095952A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11222794A (en) * 1998-02-02 1999-08-17 Oji Paper Co Ltd Low-density formed product
JP2000107002A (en) * 1998-10-07 2000-04-18 Yuto O Vegetable fiber disposable container/tool, manufacture thereof and metallic mold manufacturing container/tool
JP2000202844A (en) * 1999-01-13 2000-07-25 Ohbayashi Corp Manufacture of spontaneously decomposable molding
KR20010106334A (en) * 2001-10-19 2001-11-29 김휘주 Applying Method of Barrier Coating Material to Starch Foamed Articles by Phase Transform and Equilibrium during the Process

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11222794A (en) * 1998-02-02 1999-08-17 Oji Paper Co Ltd Low-density formed product
JP2000107002A (en) * 1998-10-07 2000-04-18 Yuto O Vegetable fiber disposable container/tool, manufacture thereof and metallic mold manufacturing container/tool
JP2000202844A (en) * 1999-01-13 2000-07-25 Ohbayashi Corp Manufacture of spontaneously decomposable molding
KR20010106334A (en) * 2001-10-19 2001-11-29 김휘주 Applying Method of Barrier Coating Material to Starch Foamed Articles by Phase Transform and Equilibrium during the Process

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