KR20200075674A - Molding apparatus of both sides heating type for foam sheet and molding method using the same - Google Patents

Abstract

The present invention relates to a foam sheet molding device comprising: a cavity with an average temperature of the inner circumference in a range of 20 to 60°C; and a plug having an average surface temperature of a protrusion part in the range of 60 to 90°C, and to a molding method, thereby increasing processability of the foam sheet and improving production efficiency.

Description

Double-sided heating type foam sheet forming device and molding method using the same{MOLDING APPARATUS OF BOTH SIDES HEATING TYPE FOR FOAM SHEET AND MOLDING METHOD USING THE SAME}

The present invention relates to a molding apparatus capable of efficiently molding a foam sheet and a molding method using the same.

In the conventional foam production, a separately manufactured resin chip is introduced into the foaming process to produce a foam.

However, when the resin chip is separately manufactured and introduced into the foaming process, after the resin is synthesized, a process of manufacturing the resin chip, a process of drying the manufactured resin chip, and a process of heating and melting the manufactured resin chip again are performed.

At this time, the process efficiency is reduced due to each process of manufacturing, drying, and reheating the resin, and denaturation of the resin may be caused.

Therefore, there is a need to develop a new foaming method that can increase process efficiency and uniformize the quality of the foam.

Korean Patent Publication No. 2004-0059325

An object of the present invention is to provide a foam sheet forming apparatus and a molding method that can improve the processability of the foam sheet and improve production efficiency.

In order to solve the above problems, as an example, the present invention,

A cavity for determining the shape of the outer circumferential surface of the foam sheet to be formed, and when forming, a cavity having an average inner circumferential surface temperature of the groove in the range of 20°C to 60°C; And

It provides a foam sheet forming apparatus comprising a plug corresponding to the groove portion of the cavity in the state where the foam sheet is placed, and when forming, a plug having an average surface temperature in the range of 60 to 90°C.

As another example, the present invention,

On the first side of the foam sheet, it is heated and pressurized at an average temperature in the range of 20°C to 60°C, and at the same time

The second side of the foam sheet provides a foam sheet forming method comprising a foam sheet forming step of heating and pressing at an average temperature in the range of 60°C to 90°C.

The foam sheet forming apparatus and the molding method according to the present invention can improve the processability for the foam sheet and improve production efficiency.

1 is a schematic view showing a molding apparatus according to the present invention.

The present invention can be applied to various changes and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description.

However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In the description of the present invention, when it is determined that a detailed description of related known technologies may obscure the subject matter of the present invention, the detailed description will be omitted.

Terms such as first and second can be used to describe various components, but the components should not be limited by the terms. The terms are only used to distinguish one component from other components.

The terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present invention, terms such as "comprises" or "have" are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

Therefore, the configuration illustrated in the embodiments described in this specification is only one of the most preferred embodiments of the present invention and does not represent all of the technical spirit of the present invention, and various equivalents that can replace them at the time of this application And variations.

Hereinafter, a method of manufacturing a foam according to the present invention will be described in detail.

The molding apparatus according to the present invention is an apparatus for molding a foam sheet that is a foam in the form of a sheet, and includes a cavity for determining the lower shape of the foamed sheet to be molded and a plug for determining the upper shape of the foamed sheet to be molded. The cavity is also called a lower forming frame, and the plug is also called an upper forming frame. The molding device simultaneously performs heating and pressing in the process of molding the foam sheet. The elongation of the foam sheet is increased through heating, and a three-dimensional shape of the foam sheet is realized through pressing.

The molding apparatus according to the present invention applies pressure while the cavity and the plug are engaged while the foam sheet is placed, and at the same time, heat is applied from both sides of the cavity and the plug. When the object of molding is resin, even if heat is applied only to the plug side, no particular problem may occur in the molding process. However, when the object of molding is a foam, a large number of air layers having a cell structure are formed inside the foam itself, which causes a decrease in thermal conductivity. That is, in the process of forming the foam sheet, if heat is applied only from the plug side, the temperature on the opposite side of the foam sheet cannot be raised to a level that can be molded. As a result, cracks or the like are generated on the surface of the foam sheet in contact with the cbit side, which leads to product defects.

In one example, the molding apparatus according to the present invention, the temperature applied by the cavity and the plug can be set differently. The temperature difference applied by the cavity and the plug is 20°C or higher, 0°C to 70°C, 0°C to 60°C, 0°C to 50°C, 0°C to 40°C, 0°C to 30°C, 0°C to 20°C, 10℃ to 70℃, 10℃ to 60℃, 10℃ to 50℃, 10℃ to 40℃, 10℃ to 30℃, 10℃ to 20℃, 20℃ to 70℃, 20℃ to 60℃, 20℃ To 50 °C, 20 °C to 40 °C, 20 °C to 30 °C, 30 °C to 70 °C, 30 °C to 60 °C, 30 °C to 50 °C, 30 °C to 40 °C, 40 °C to 70 °C, 40 °C to 60 °C ℃, 40 ℃ to 50 ℃, may be in the range of 50 ℃ to 70 ℃ or 50 ℃ to 60 ℃.

As one embodiment, the foam sheet forming apparatus according to the present invention,

A cavity for determining the shape of the outer circumferential surface of the foam sheet to be formed, and when forming, a cavity having an average inner circumferential surface temperature of the groove in the range of 20°C to 60°C; And

It includes a protrusion corresponding to the groove portion of the cavity in the state where the foam sheet is placed, and when forming, includes a plug having an average surface temperature of 60 to 90°C.

The plug serves to heat the foam sheet to a temperature suitable for molding into a three-dimensional shape and to apply pressure at the same time. The surface temperature of the protruding portion of the plug is in the range of 60°C to 90°C on average, and specifically, may be 70°C or higher.

In addition, in the process of forming the foam sheet, the cavity supports the lower surface of the foam sheet and simultaneously serves as a lower molding frame. The temperature of the inner circumferential surface of the groove of the cavity ranges from an average of 20°C to 60°C, and may specifically be 40°C or more. If the temperature on the cavity side is too low, the problem of cracking on the surface cannot be solved. On the contrary, when the temperature of the cavity is too high, there is a problem that the foamed sheet whose molding process is completed cannot be easily separated from the molding apparatus. That is, if the surface temperature of the cavity is too high, the surface of the foam sheet in contact with the cavity may be partially melted, whereby the foam sheet and the cavity may be temporarily bonded. If the foam sheet is forcibly released while the foam sheet and the cavity are temporarily bonded, a defect occurs in the foam sheet. In severe cases, the foam separated from the foam sheet may remain on the cavity surface and contaminate the molding apparatus.

As one example, in the forming apparatus, the temperature of the inner peripheral surface of the groove portion of the cavity may range from an average of 20°C to 60°C, and the surface temperature of the protruding portion of the plug may range from an average of 60°C to 90°C. At this time, the difference between the temperature of the inner circumferential surface of the cavity and the surface temperature of the protruding portion of the plug can be controlled to 15°C or higher, specifically 25°C or higher, or 30°C or higher. This is a case where the temperature difference between the two sides is largely set by lowering the temperature of the cavity relatively and the temperature of the plug relatively high. Through this, it is possible to control the crystallinity of both sides of the foam sheet to a desired level, respectively.

As another example, in the molding apparatus, the inner circumferential surface temperature of the cavity is on average 20°C to 60°C, 20°C to 55°C, 20°C to 50°C, 20°C to 45°C, 20°C to 40°C, 20 ℃ to 35℃, 20℃ to 30℃, 30℃ to 60℃, 30℃ to 55℃, 30℃ to 50℃, 30℃ to 45℃, 30℃ to 40℃, 30℃ to 35℃, 35℃ to 60℃, 35℃ to 55℃, 35℃ to 50℃, 35℃ to 45℃, 35℃ to 40℃, 40℃ to 60℃, 40℃ to 55℃, 40℃ to 50℃, 40℃ to 45℃ , 50 °C to 60 °C, 25 °C to 50 °C, 25 °C to 40 °C or 25 °C to 35 °C, and the average surface temperature of the protrusions of the plug is 60 °C to 90 °C, 60 °C to 85 °C, 60 °C to 80 °C ℃, 60℃ to 75, 60℃ to 70℃, 60℃ to 65℃, 65℃ to 90℃, 65℃ to 85℃, 65℃ to 80℃, 65℃ to 75, 65℃ to 70℃, 70℃ It may be in the range of 90 °C, 70 °C to 85 °C, 70 °C to 80 °C, 70 °C to 75, 80 °C to 90 °C, 75 °C to 90 °C or 75 °C to 85 °C. At this time, the difference between the temperature of the inner peripheral surface of the cavity and the surface temperature of the protruding portion of the plug is 25°C or less, specifically, the temperature difference between the inner surface of the groove portion of the cavity and the surface of the protruding portion of the plug is 20°C or higher, 0°C to 70°C, 0°C to 60℃, 0℃ to 50℃, 0℃ to 40℃, 0℃ to 30℃, 0℃ to 20℃, 10℃ to 70℃, 10℃ to 60℃, 10℃ to 50℃, 10℃ to 40℃ , 10℃ to 30℃, 10℃ to 20℃, 20℃ to 70℃, 20℃ to 60℃, 20℃ to 50℃, 20℃ to 40℃, 20℃ to 30℃, 30℃ to 70℃, 30 It can be controlled to ℃ to 60 ℃, 30 ℃ to 50 ℃, 30 ℃ to 40 ℃, 40 ℃ to 70 ℃, 40 ℃ to 60 ℃, 40 ℃ to 50 ℃, 50 ℃ to 70 ℃ or 50 ℃ to 60 ℃ have. This is the case when the temperature difference between the cavity and the plug is set small. Through this, the crystallinity of both sides of the foam sheet can be similarly formed, and product uniformity can be increased.

In one example, each of the cavity and the plug has a structure in which a heating portion is formed. The heating portion of the cavity and plug is not particularly limited, but may be, for example, a structure heated by heating elements that generate heat through electrical resistance. Or any one or more of the cavity and the plug may be a structure that is heated using a fruit, respectively. Specifically, any one or more of the cavity and the plug may have a structure in which fluid supply lines for supplying heated air are formed.

In another example, a line for pressure reduction may be formed on one side of the cavity. In the process of forming the foam sheet, it is possible to increase the molding efficiency by forming a vacuum or a vacuum in the groove portion of the cavity.

The present invention also provides a method for molding a foam sheet using the molding apparatus described above.

As one example, the foam sheet forming method according to the present invention,

On the first side of the foam sheet, it is heated and pressurized at an average temperature in the range of 20°C to 60°C, and at the same time

The second surface of the foam sheet includes a foam sheet forming step of heating and pressing at a temperature in the range of 60°C to 90°C on average.

The present invention is differentiated from the conventional molding method in that it forms a foam, not an unfoamed resin. Furthermore, in the molding method according to the present invention, heating and pressing are performed simultaneously on both sides of the foam sheet to be formed.

In one example, the foam sheet may be introduced to a foam sheet forming step after a preheating step. In the foam sheet manufactured through the extrusion process, post-foaming occurs when heat is applied. During the post-foaming process, the volume of the foam sheet increases to a certain level, for example, 1.5 to 2 times. If such post-foaming occurs in the forming step, it may affect the forming form. In addition, by heat treatment before the forming step, there is also an effect of heating the foam sheet to a predetermined temperature or more in advance. Therefore, by preheating the foam sheet introduced in the molding step, the efficiency of the work is increased, and the defect rate is lowered. In the preheating step, for example, the foam can be heated in the range of 40°C to 120°C, and the heating time can be adjusted in the range of 10 seconds to 30 minutes.

When the foam sheet is heated and then cooled, it is common to increase the crystallinity of the foam sheet. The crystallinity may increase as the heating temperature and cooling time of the foam sheet increase.

In one embodiment, the crystallinity of the foam sheet introduced in the foam sheet forming step may be controlled in the range of 8 to 15%. This is possible by manufacturing a foamed sheet having a crystallinity of the above range, or by using a foamed sheet having a controlled crystallinity through a preheating process. In addition, the crystallinity of the foam sheet subjected to the foam sheet forming step can be controlled in the range of 25 to 35%. For example, when manufacturing a deep container having a depth of 7 cm or more, the crystallinity of the foam sheet introduced in the molding step is set low. This is because the foamed sheet with low crystallinity is relatively excellent in moldability. And, the forming step is performed at a relatively high temperature. The foam sheet molded at a high temperature greatly increases the crystallinity during the cooling process. The foamed sheet with high crystallinity increases hardness.

In another embodiment, the crystallinity of the foam sheet introduced in the foam sheet forming step may be controlled in the range of 12% to 17%. This is possible by manufacturing a foamed sheet having a crystallinity of the above range, or by using a foamed sheet having a controlled crystallinity through a preheating process. In addition, the crystallinity of the foam sheet subjected to the foam sheet forming step can be controlled in the range of 18 to 25%. For example, when manufacturing a container having a depth of less than 7 cm, the crystallinity of the foam sheet introduced in the molding step is maintained at an appropriate level. When the crystallinity of the foam sheet is lowered, the elongation increases, but there is a problem that workability decreases. And, the molded foam sheet increases the crystallinity in the cooling process, it is controlled in the range of 18 to 25%.

The foam sheet according to the present invention may be a polyester resin foam sheet. Specifically, the type of the polyester resin, polyethylene terephthalate (Polyethylene Terephthalate, PET), polybutylene terephthalate (Polybutylene Terephthalate, PBT), poly lactic acid (Poly Lactic acid, PLA), polyglycolic acid ( Polyglycolic acid, PGA, Polypropylene, PP, Polyethylene, PE, Polyehtylene adipate, PEA, Polyhydroxyalkanoate, PHA, Polytrimethylene Terephthalate , PTT) and polyethylene naphthalate (PEN). Specifically, in the present invention, the foamed sheet may be a polyethylene terephthalate (PET) resin foamed sheet.

As an example, the foam sheet introduced in the foam sheet processing step may have a structure in which one or both skin layers are formed. The skin layer means a region having a relatively small cell size. For example, the skin layer may have an average cell size of 100 μm or less, and an average cell size of the remaining regions other than the skin layer may range from 200 μm or more.

The foam sheet according to the present invention is manufactured through an extrusion process. Specifically, a foam sheet is produced by extruding and foaming a polyester resin. The process of manufacturing the foam sheet based on the polyester resin is as follows.

Specifically, the type of the polyester resin, polyethylene terephthalate (Polyethylene Terephthalate, PET), polybutylene terephthalate (Polybutylene Terephthalate, PBT), poly lactic acid (Poly Lactic acid, PLA), polyglycolic acid ( Polyglycolic acid, PGA, Polypropylene, PP, Polyethylene, PE, Polyehtylene adipate, PEA, Polyhydroxyalkanoate, PHA, Polytrimethylene Terephthalate , PTT) and polyethylene naphthalate (PEN). Specifically, polyethylene terephthalate (PET) may be used in the present invention.

The resin polymerization process for producing the polyester resin can be performed through various synthetic routes, and is not particularly limited. For example, after mixing the aromatic dicarboxylic acid and glycol component, the polyester resin is melted at a temperature of 200° C. or higher, a catalyst is added to the melted mixture, and the temperature is 200 to 250° C. for 1 to 6 hours. While preparing an oligomer through an esterification reaction or transesterification reaction, a step of flowing out by-products such as water or methanol, and the prepared oligomer at a temperature of 260 to 290°C and a vacuum condition of 1 Torr or less, for 1 to 6 hours. It is possible to manufacture through the step of condensation polymerization reaction.

As an example, the present invention can provide a foam of a flame retardant polyester resin into which a flame retardant is added. Types of flame retardants include reactive flame retardants and additive flame retardants.

When using a reactive flame retardant, a polymerization process may be performed by adding a flame retardant during resin synthesis. Through this, a flame-retardant polyester resin can be produced and foamed to increase the flame retardancy of the foam. For example, the polyester resin produced in the resin polymerization process in the present invention may be a flame retardant polyester resin having a phosphorus (P) content in the range of 2,000 to 20,000 ppm.

In some cases, an additive type flame retardant may be added to one side of the extruder to produce a flame retardant foam. The type of the additive flame retardant is not particularly limited, and for example, AODD product of Synergy Material Co. Ltd. may be used.

Alternatively, it is also possible to use a reactive flame retardant and an additive flame retardant simultaneously.

In the present invention, the foaming process of foaming the polyester resin to produce a foam can be performed using various types of extruders. The foaming process can be carried out largely through bead foaming or extrusion foaming, and extrusion foaming is preferred. The extrusion foam, by continuously extruding and foaming the resin melt, it is possible to simplify the process step, it is possible to mass-produce, and prevents cracking, granular fracture phenomenon, etc. between the beads during foam expansion, and provides better flexural strength. And compressive strength.

As one example, in the method for manufacturing a foam according to the present invention, various types of additives may be introduced. If necessary, the additive may be introduced in the fluid connection line or in the foaming process. Examples of additives may have a hydrophilicity function, a waterproofing function, a flame retardant function or a UV blocking function, and a thickener, a surfactant, a UV blocking agent, a hydrophilizing agent, a flame retardant, a heat stabilizer, a waterproofing agent, a cell size expander, an infrared attenuator, It may include one or more functional additives selected from the group consisting of plasticizers, fire retardant chemicals, pigments, elastomers, extrusion aids, antioxidants, nucleating agents, anti-static agents and UV absorbers. Specifically, the foam manufacturing method of the present invention may be added one or more of the thickener, nucleating agent, thermal stabilizer and blowing agent, may further include one or more of the functional additives listed above.

For example, the foam manufacturing method of the present invention is a thickener, flame retardant, surfactant, sunscreen, hydrophilic agent, flame retardant, heat stabilizer, waterproofing agent, cell size expander, infrared attenuator, plasticizer, fire retardant chemical, pigment, elastomer , One or more additives selected from the group consisting of extrusion aids, antioxidants, nucleating agents, anti-static agents and UV absorbers can be introduced into the fluid connection line. Among the additives required for foam production, additives not introduced in the fluid connection line can be added during the extrusion process.

The thickener is not particularly limited, but in the present invention, for example, pyromellitic dianhydride (PMDA) may be used.

Examples of the nucleating agent, talc, mica, silica, diatomaceous earth, alumina, titanium oxide, zinc oxide, magnesium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, potassium carbonate, calcium carbonate, magnesium carbonate, calcium sulfate, barium sulfate , Inorganic compounds such as sodium hydrogen carbonate and glass beads. Such a nucleating agent may serve to impart the functionality of the resin foam, reduce the cost, and the like. Specifically, talc may be used in the present invention.

The heat stabilizer may be an organic or inorganic phosphorus compound. The organic or inorganic phosphorus compound may be, for example, phosphoric acid and its organic ester, phosphorous acid and its organic ester. For example, the thermal stabilizer is a commercially available material, and may be phosphoric acid, alkyl phosphate or aryl phosphate. Specifically, in the present invention, the thermal stabilizer may be triphenyl phosphate, but is not limited thereto. If the thermal stability of the resin foam can be improved, it can be used without limitation within a typical range.

Examples of the foaming agent include N ₂ , CO ₂ , Freon, butane, pentane, neopentane, hexane, isohexane, heptane, isoheptane, methyl chloride, or a physical foaming agent or azodicarbonamide compound, P, P'-oxybis(benzenesulfonyl hydrazide) [P,P'-oxy bis (benzene sulfonyl hydrazide)] compound, N,N'-dinitrosopentamethylenetetraamine (N,N'-dinitroso pentamethylene There are chemical blowing agents such as tetramine)-based compounds, and specifically, CO ₂ may be used in the present invention.

In the present invention, the flame retardant is meant to encompass the reactive flame retardant and/or additive flame retardant described above, and as an example, an additive flame retardant may be added as an additive. The type of the flame retardant is not particularly limited, and may include, for example, one or more of bromine compounds, phosphorus or phosphorus compounds, antimony compounds, and metal hydroxides. Bromine compounds include, for example, tetrabromo bisphenol A, decabromodiphenyl ether, and the like, and phosphorus or phosphorus compounds include aromatic phosphate esters, aromatic condensed phosphate esters, halogenated phosphate esters, reds, and the like, and antimony compounds Antimony trioxide, antimony pentoxide, and the like. Further, as the metal element in the metal hydroxide, aluminum (Al), magnesium (Mg), calcium (Ca), nickel (Ni), cobalt (Co), tin (Sn), zinc (Zn), copper (Cu) ), iron (Fe), titanium (Ti), and boron (B). Especially, aluminum, magnesium, etc. are preferable. The metal hydroxide may be composed of one metal element or two or more metal elements. For example, a metal hydroxide composed of one type of metal element may include aluminum hydroxide, magnesium hydroxide, and the like.

The surfactant is not particularly limited, and anionic surfactants (eg, fatty acid salts, alkyl sulfate ester salts, alkylbenzenesulfonic acid salts, alkylnaphthalenesulfonic acid salts, alkylsulfosuccinic acid salts, polyoxyethylene alkyl sulfate ester salts, etc.) , Nonionic surfactants (e.g., polyoxyalkylene alkyl ethers such as polyoxyethylene alkyl ethers, polyoxyethylene derivatives, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, Glycerin fatty acid esters, polyoxyethylene alkylamines, alkyl alkanolamides, etc.), cationic and amphoteric surfactants (eg, alkylamine salts, quaternary ammonium salts, alkylbetaines, amine oxides, etc.) and water-soluble polymers Or protective colloids (e.g. gelatin, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, polyethylene glycol, polyoxyethylene-polyoxypropylene block copolymer, polyacrylamide, polyacrylic acid, polyacrylic Acid salts, sodium alginate, polyvinyl alcohol partial saponification, and the like).

In addition, the waterproofing agent is not particularly limited, for example, silicone-based, epoxy-based, cyano-acrylic acid-based, polyvinyl acrylate-based, ethylene-vinyl acetate-based, acrylate-based, polychloroprene-based, polyurethane resins and polyester resins It may include a mixture of a mixture of a series, a mixture of polyol and polyurethane series, a series of a mixture of acrylic polymer and polyurethane resin, a series of polyimide and a series of cyanoacrylate and urethane.

Further, the sunscreen is not particularly limited, and may be, for example, an organic or inorganic sunscreen, and examples of the organic sunscreen include p-aminobenzoic acid derivatives, benzylidene campo derivatives, cinnamic acid derivatives, benzophenone derivatives, Benzotriazole derivatives and mixtures thereof, and examples of the inorganic sunscreen may include titanium dioxide, zinc oxide, manganese oxide, zirconium dioxide, cerium dioxide, and mixtures thereof.

Hereinafter, the present invention will be described with reference to the drawings, but the scope of the present invention is not limited thereto.

1 is a schematic view showing an apparatus for forming a foam sheet according to one embodiment of the present invention. The molding apparatus includes a cavity 120 corresponding to the lower molding frame and a plug 110 corresponding to the upper molding frame. The cavity 120 includes a groove portion for determining the shape of the outer circumferential surface of the foam sheet 200 to be formed, and the plug 110 corresponds to the groove portion of the cavity 120 in the state where the foam sheet 200 is placed. It includes a protrusion.

In one embodiment, the surface temperature of the groove portion of the cavity 120 is an average of 20°C to 60°C, and the surface temperature of the protruding portion of the plug 110 is controlled to an average of 60°C to 90°C. By increasing the temperature difference between the cavity 120 and the plug 110, it is possible to control the crystallinity of both sides of the molded foam sheet differently.

In another embodiment, the surface temperature of the groove portion of the cavity 120 averages 20°C to 60°C, 20°C to 55°C, 20°C to 50°C, 20°C to 45°C, 20°C to 40°C, 20 ℃ to 35℃, 20℃ to 30℃, 30℃ to 60℃, 30℃ to 55℃, 30℃ to 50℃, 30℃ to 45℃, 30℃ to 40℃, 30℃ to 35℃, 35℃ to 60℃, 35℃ to 55℃, 35℃ to 50℃, 35℃ to 45℃, 35℃ to 40℃, 40℃ to 60℃, 40℃ to 55℃, 40℃ to 50℃, 40℃ to 45℃ , 50 °C to 60 °C, 25 °C to 50 °C, 25 °C to 40 °C, or 25 °C to 35 °C, and the surface temperature of the protrusions of the plug 110 averages 60 °C to 90 °C, 60 °C to 85 °C, 60 °C To 80 ℃, 60 ℃ to 75, 60 ℃ to 70 ℃, 60 ℃ to 65 ℃, 65 ℃ to 90 ℃, 65 ℃ to 85 ℃, 65 ℃ to 80 ℃, 65 ℃ to 75, 65 ℃ to 70 ℃, It can be controlled in the range of 70 ℃ to 90 ℃, 70 ℃ to 85 ℃, 70 ℃ to 80 ℃, 70 ℃ to 75, 80 ℃ to 90 ℃, 75 ℃ to 90 ℃ or 75 ℃ to 85 ℃. In addition, the difference in temperature between the inner circumferential surface of the groove portion of the cavity and the surface of the protruding portion of the plug is 20°C or higher, 0°C to 70°C, 0°C to 60°C, 0°C to 50°C, 0°C to 40°C, 0°C to 30°C, 0℃ to 20℃, 10℃ to 70℃, 10℃ to 60℃, 10℃ to 50℃, 10℃ to 40℃, 10℃ to 30℃, 10℃ to 20℃, 20℃ to 70℃, 20℃ To 60°C, 20°C to 50°C, 20°C to 40°C, 20°C to 30°C, 30°C to 70°C, 30°C to 60°C, 30°C to 50°C, 30°C to 40°C, 40°C to 70°C It can be controlled to ℃, 40 ℃ to 60 ℃, 40 ℃ to 50 ℃, 50 ℃ to 70 ℃ or 50 ℃ to 60 ℃. By lowering the temperature difference between the cavity 120 and the plug 110 as described above, the crystallinity of both sides of the molded foam sheet can be similarly formed, and product uniformity can be increased.

In addition, the present invention can provide a food container including a polyester resin foam sheet having a structure structured in a three-dimensional shape and a crystallinity of 18 to 35%. For example, the food container of the present invention can be manufactured through the foam sheet forming method according to the present invention.

Here, the term'structured in a three-dimensional shape' has a three-dimensional structure, and is not limited as long as it is a structure capable of containing a solid or liquid. Specifically, the structure structured in a three-dimensional shape may be a ball shape or a column shape having one side open and having a height higher than a predetermined length. More specifically, it may be in the form of a ball, a rectangular parallelepiped with one surface open, a cylinder with one surface open, or a hexagonal column with one surface open.

Specifically, the type of the polyester resin, polyethylene terephthalate (Polyethylene Terephthalate, PET), polybutylene terephthalate (Polybutylene Terephthalate, PBT), poly lactic acid (Poly Lactic acid, PLA), polyglycolic acid ( Polyglycolic acid, PGA, Polypropylene, PP, Polyethylene, PE, Polyehtylene adipate, PEA, Polyhydroxyalkanoate, PHA, Polytrimethylene Terephthalate , PTT) and polyethylene naphthalate (PEN). Specifically, in the present invention, the foam sheet may be a polyethylene terephthalate (PET) resin foam sheet.

In one example, the crystallinity of the food container according to the present invention may be 18 to 35%. Specifically, the crystallinity of the food container may be 18 to 25%, 20 to 30%, or 25 to 35%. By having the crystallinity as described above, the food container of the present invention can have excellent strength and formability.

In one example, the food container of the present invention can exhibit excellent heat resistance. Specifically, the food container may include a foam sheet satisfying Equation 1 below:

[Equation 1]

50% ≤|V ₁ -V ₀ | / V ₀ x 100 ≤ 300%

In Equation 1,

V ₀ is the volume of the foam sheet before exposing the circular food container having a diameter of 10 cm in a 200° C. oven for 30 seconds, the unit is cm ³ ,

V ₁ is the volume of the foam sheet, and the unit is cm ³ after exposing the circular food container having a diameter of 10 cm in an oven at 200° C. for 30 seconds.

Specifically, the rate of dimensional change before and after exposing the sample of a circular food container having a diameter of 10 cm in an oven at 200° C. for 30 seconds was measured. This is a measure corresponding to the actual use environment in the heat of the food container containing the food container. For example, the volume may mean a value calculated by multiplying the length, width, and thickness of each food container. For example, the rate of dimensional change according to Equation 1 is 50% to 300%, 50% to 250%, 50% to 200%, 50% to 100%, 100% to 300%, 100% to 250%, 100 % To 200%, 100% to 150%, 150% to 300%, 150% to 250%, 150% to 200%, 200% to 300%, 200% to 250% or 50 to 150%. By satisfying the value of Equation 1 in the above range, it can be seen that the food container according to the present invention hardly undergoes a morphological change even in use in a high temperature environment. As a result, it can be seen that the food container according to the present invention has excellent durability.

In another example, the food container of the present invention may have a structure in which a skin layer is formed on one side or both sides of the foam sheet. Specifically, the skin layer is composed of a polyester resin, and an average cell size may be 100 μm or less.

The present invention can provide a food container manufactured by molding a polyester resin foam sheet. As one example, the food packaging container may be lightweight and have excellent strength, and may have excellent durability against temperature changes. Therefore, it can be used in a microwave oven directly without having to transfer it to a separate microwave oven container.

110: plug
120: cavity
200: foam sheet

Claims (13)

A cavity for determining the shape of the outer circumferential surface of the foam sheet to be molded, and when forming, a cavity having an average inner circumferential surface temperature of the groove in the range of 20°C to 60°C; And
A foam sheet forming apparatus comprising a plug corresponding to a groove portion of a cavity in the state where the foam sheet is placed, and a plug having an average surface temperature in the range of 60°C to 90°C during molding.
According to claim 1,
The temperature of the inner circumferential surface of the groove of the cavity ranges from an average of 25°C to 55°C,
The surface temperature of the projections of the plugs ranges from an average of 75°C to 90°C,
A foam sheet forming apparatus with a difference between the temperature of the inner circumferential surface of the cavity and the surface temperature of the protruding part of the plug being 20°C or higher.
According to claim 1,
The temperature of the inner circumferential surface of the groove of the cavity ranges from an average of 35°C to 50°C,
The surface temperature of the protrusions of the plugs ranges from an average of 70°C to 90°C,
A foam sheet forming apparatus with a difference between the temperature of the inner circumferential surface of the cavity and the surface temperature of the protruding part of the plug being 25°C or less.
According to claim 1,
The cavity and the plug are foam sheet forming devices, each of which is heated by a heating element that generates heat through electrical resistance.
According to claim 1,
The cavity and the plug are foam sheet forming apparatuses each having a structure that is heated using a fruit.
On the first side of the foam sheet, it is heated and pressurized at an average temperature in the range of 20°C to 60°C, and at the same time
The second side of the foam sheet is a foam sheet forming method comprising a foam sheet forming step of heating and pressing at a temperature ranging from an average of 60°C to 90°C.
The method of claim 6,
The foam sheet introduced in the foam sheet forming step, the foam sheet forming method characterized in that it has undergone a preheat treatment step.
The method of claim 6,
Crystallinity of the foam sheet introduced in the foam sheet forming step is 8 to 15%,
Foaming sheet forming method characterized in that the crystallinity of the foamed sheet after the foaming sheet forming step is 25 to 35%.
The method of claim 6,
Crystallinity of the foam sheet introduced in the foam sheet forming step is 12% to 17%,
Foaming sheet forming method characterized in that the crystallinity of the foamed sheet after the foaming sheet forming step is 18 to 25%.
The method of claim 6,
The foam sheet is a foam sheet molding method characterized in that the polyester resin foam sheet.
The method of claim 6,
The foam sheet introduced in the foam sheet processing step,
One or both sides have a structure in which a skin layer is formed,
The skin layer is a foam sheet forming method, characterized in that the average cell size is 100 ㎛ or less.
It is a structured structure in three-dimensional shape,
Crystallinity comprises a polyester resin foam sheet of 18 to 35%,
The foam sheet is a food container characterized in that it satisfies the following Equation 1:
[Equation 1]
50% ≤|V ₁ -V ₀ | / V ₀ x 100 ≤ 300%
In Equation 1,
V ₀ is the volume of the foam sheet before exposing the circular food container having a diameter of 10 cm in a 200° C. oven for 30 seconds, the unit is cm ³ ,
V ₁ is the volume of the foam sheet, and the unit is cm ³ after exposing the circular food container having a diameter of 10 cm in an oven at 200° C. for 30 seconds.
The method of claim 12,
Food container characterized in that the skin layer is formed on one or both sides of the foam sheet.

Images