KR20210087587A - Polyester resin foam sheet having regions having different thicknesses and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a polyester resin foam sheet and a method for manufacturing the same, and by including regions having different thicknesses and cell sizes in the width direction of a foam sheet, it is possible to increase processability for the manufactured foam sheet and reduce process variables. The foam sheet includes a region having a thickness of D1 and a region having a thickness of D2 based on a cross-section in the width direction (TD) of the foam sheet, and a ratio of D1 to D2 is in the range of 5 : 1 to 1.2 : 1.

Description

Polyester resin foam sheet including regions having different thicknesses in the width direction and manufacturing method thereof

The present invention relates to a polyester resin foam sheet including regions having different thicknesses and cell sizes in the width direction, and a method for manufacturing the same.

Polyester resin has excellent mechanical and chemical properties, so it can be used in various fields, for example, drinking water containers, medical devices, food packaging, food containers, sheets, films, or automobile molded products. available for use For example, a polyester resin having crystallinity such as polyethylene terephthalate (PET) has excellent mechanical properties and excellent heat resistance and chemical resistance compared to polyethylene-based resins or polypropylene-based resins.

In particular, the foam sheet using the polyester resin has excellent lightness and strength, and can be molded and processed into a molded body having a three-dimensional shape through thermoforming or the like. However, the polyester resin foam sheet has disadvantages in that it is difficult to give a desired shape by thermoforming or the like due to high rigidity, and it is easily broken. In addition, the polyester foam sheet is subjected to a thermoforming process of applying heat and pressure according to its use. In the process of thermoforming the foam sheet, the degree of crystallinity for each part or mechanical or physical properties are changed. This causes an unexpected change in physical properties of the foam sheet, and causes it to act as a processing variable.

Therefore, it is required to develop a polyester foam sheet that has excellent thermoformability and can minimize the change in physical properties during the molding process.

Japanese Patent Laid-Open No. 2015-189835

The present invention has been devised to solve the above problems, and an object of the present invention is to provide a polyester resin foam sheet including regions having different thicknesses and cell sizes in the width direction, and a method for manufacturing the same.

The polyester resin foam sheet according to the present invention relates to a polyester resin foam sheet in which 90% or more of the cells are closed cells (DIN ISO4590).

Specifically, the foam sheet includes a region having a thickness of D1 and a region having a thickness of D2, based on the cross-section in the width direction (TD) of the foam sheet, and the ratio of D1 and D2 is 5:1 to 1.2:1 is the range In addition, the average cell size (F1) of the region having the thickness D1 is larger than the average cell size (F2) of the region having the thickness D2, the average cell size (F1) of the region having the thickness D1 and the average cell size of the region having the thickness D2 The deviation of the average cell size F2 is 20% or more.

In a specific example, the average cell size F1 of the region having the thickness D1 and the average cell size F2 of the region having the thickness D2 satisfy Equation 1 below.

[Formula 1]

20(%) ≤ ((|F _x -F _mean |)/F _mean )x100 ≤ 90(%)

In Equation 1,

F _x represents the value of F1 or F2,

F _mean represents the average value of the numerical values of F1 and F2.

For example, in the region having a thickness D1, the average thickness D1 is in the range of 1.5 mm to 5 mm, and the average cell size F1 is in the range of 150 to 650 μm.

For another example, in the region having a thickness D2, the average thickness D2 is in the range of 0.5 mm to 3 mm, and the average cell size F1 is in the range of 50 to 250 μm.

The overall cell size of the foam sheet according to the present invention ranges from 80 μm to 600 μm on average.

In another example, the foam sheet comprises 0.5% to 5% by weight of calcium carbonate.

In a specific example, the polyester resin is a polyethylene terephthalate resin.

The present invention also provides a method for manufacturing the polyester resin foam sheet described above.

In one example, the method for manufacturing a polyester resin foam sheet according to the present invention comprises the steps of: extruding and foaming a polyester resin through a discharge port having a ring-shaped cross-section perpendicular to the discharge direction; Partially cooling one side of the extruded and foamed cylindrical sheet; and cutting the extruded and foamed cylindrical sheet in the discharge direction.

In a specific example, in the manufacturing method of the foam sheet, in the step of partially cooling one side of the extruded and foamed cylindrical sheet, it is possible to simultaneously perform the step of partially heating the other side of the extruded and foamed cylindrical sheet Do.

In another example, the method for manufacturing a polyester resin foam sheet according to the present invention comprises the steps of extruding and foaming a polyester resin through a discharge port having a ring-shaped cross-section perpendicular to the discharge direction; Partially heating one side of the extruded and foamed cylindrical sheet; and cutting the extruded and foamed cylindrical sheet in the discharge direction.

In a specific example, the step of extruding and foaming the above-mentioned polyester resin is carried out through the step of introducing a polyester resin and calcium carbonate to the extruder and extrusion foaming to prepare a foam sheet, and the content of the calcium carbonate is 0.5% to 5% by weight.

The polyester resin foam sheet and its manufacturing method according to the present invention include regions having different thicknesses and cell sizes in the width direction of the foam sheet, thereby increasing processability for the manufactured foam sheet and reducing process variables.

1 is a schematic diagram showing a foaming process of a polyester resin according to an embodiment of the present invention.
2 is a schematic diagram showing a vertical cross-section with respect to the discharge direction of the annular nozzle according to an embodiment of the present invention.
3 to 6 are schematic views showing a cross-section in the width direction of the polyester foam resin according to an embodiment of the present invention, respectively.

Hereinafter, the present invention will be described in detail. Prior to this, the terms or words used in the present specification and claims are not to be construed as being limited to their ordinary or dictionary meanings, and the inventor must properly understand the concept of the term in order to best describe his invention. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined in

Since the present invention can have various changes and can have various embodiments, specific embodiments are 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 it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

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

In addition, in the present invention, the "width direction" refers to a direction indicating the width of the polyester resin foam sheet, and specifically, a direction perpendicular to the direction (MD; Machine Direction) in which the polyester resin is extruded and foamed (TD; Traverse). direction).

The foam seat according to the present invention is a polyester resin foam seat in which 90% or more of the cells are closed cells (DIN ISO4590). The foam sheet includes a region having a thickness of D1 and a region having a thickness of D2 based on a cross-section in the width direction (TD) of the foam sheet, and the ratio of D1 and D2 is in the range of 5:1 to 1.2:1. This means that the foam sheet has a thickness deviation of 20% or more based on the cross-section in the width direction of the foam sheet. Specifically, the ratio of D1 to D2 is in the range of 5:1 to 2:1, in the range of 5:1 to 3:1, in the range of 3:1 to 1.2:1, in the range of 3.5:1 to 2:1, or in the range of 3:1 to It is in the 2.1:1 range. The present invention is differentiated from the case where the surface of the foam sheet is simply uneven. In the present invention, in the manufacturing process, based on the width direction of the foam sheet, a thick region and a thin region are intentionally formed. Also, the thickness is sequentially decreased or increased between the thick region and the thin region. For example, the foam seat according to the present invention, a thick region and a thin region can be formed in the range of 1 to 5, respectively.

In addition, in the polyester resin foam according to the present invention, the average cell size (F1) of the region having a thickness of D1 is larger than the average cell size (F2) of the region having a thickness of D2, and the average cell size of the region having a thickness of D1 ( The deviation between F1) and the average cell size F2 of the region having the thickness D2 is 20% or more.

The foam sheet according to the present invention includes regions having different thicknesses and cell sizes in the width direction. For example, the thick region of the foam sheet has a large cell size constituting the foam sheet, and the thin region has a small cell size constituting the foam sheet. Through this, the foam sheet can increase the degree of freedom in the processing process suitable for product use and reduce process variables.

Specifically, in the polyester resin foam sheet according to the present invention, the average cell size (F1) of the region having a thickness of D1 and the average cell size (F2) of the region having a thickness of D2 satisfy Equation 1 below.

[Formula 1]

20(%) ≤ ((|F _x -F _mean |)/F _mean )x100 ≤ 90(%)

In Equation 1,

F _x represents the value of F1 or F2,

F _mean represents the average value of the numerical values of F1 and F2.

Other ranges in Equation 1 are 20 to 90%, 10 to 50%, 30 to 50%, 45 to 90%, 60 to 90%, or 40 to 60%.

The polyester resin foam sheet according to the present invention, based on the cross-section in the width direction of the foam sheet, has an average thickness in the range of 0.5 mm to 5 mm. Specifically, the average thickness of the foam sheet is in the range of 1 mm to 5 mm, 1.5 mm to 4 mm, 2.5 mm to 4.5 mm, or 2.8 mm to 3.5 mm. The present invention provides a sheet-shaped foam.

In a specific example, in the region having the thickness D1, the average thickness D1 is in the range of 1.5 mm to 5 mm, and the average cell size F1 is in the range of 150 to 650 μm. Specifically, the average thickness D1 is in the range of 1.5 mm to 5 mm, 3 mm to 5 mm, 3.5 mm to 4.5 mm, 1.5 mm to 3 mm, or 3.5 mm to 4 mm. In addition, the cell size F1 is in the range of 150 to 650 μm, 300 to 650 μm, 150 to 650 μm, 200 to 400 μm, 150 to 300 μm, 350 to 650 μm, or 350 to 450 μm.

In another specific region having a thickness D2, the average thickness D2 is in the range of 0.5 mm to 3 mm, and the average cell size F1 is in the range of 50 to 250 μm. Specifically, the average thickness D2 is in the range of 0.5 mm to 3 mm, 0.5 mm to 2.5 mm, 1 mm to 2.5 mm, 0.5 mm to 1.5 mm, or 1 mm to 1.6 mm. In addition, the cell size F2 is in the range of 50 to 300 μm, 50 to 250 μm, 100 to 250 μm, 50 to 150 μm, or 100 to 180 μm.

In the present invention, based on the cross-section in the width direction of the foam sheet, the cell size is controlled to have a deviation of more than a certain level. In this case, it is possible to manufacture the foam sheet according to the use of the product or the demand of the consumer, and the consumer can custom-cut the foam sheet using the supplied foam sheet.

In the present invention, the deviation of the thickness and the cell size in the width direction of the foam sheet is controlled to 20% or more. For example, the region where the thickness of the foam sheet in the width direction is thick has a structure in which the cell size is also large.

The manufactured foam sheet goes through a process of processing according to its use. However, depending on the product, a thin region and a thick region are required. For this reason, in the process of processing the foam sheet, it is accompanied by a process of compressing it according to the required thickness for each area. However, in the process of molding the thickness of the foam sheet to be different, the degree of crystallinity or mechanical or physical properties for each part are changed. This causes an unexpected change in physical properties of the foam sheet, and causes it to act as a processing variable.

In the present invention, by providing a foam sheet including a thick region and a thin region, it is possible to remove variables generated in the post-processing process and increase the degree of freedom in the process during processing. At the same time, in the present invention, the number of cells on a vertical line in the cross-section in the width direction is controlled at the same or similar level for each region.

In another embodiment, the cell size of the foam sheet ranges on average from 80 μm to 600 μm. Specifically, the cell size of the foam sheet may be an average of 100 μm to 500 μm, 100 μm to 400 μm, or 350 μm to 500 μm, and more specifically, the cell size of the foam sheet is an average of 200 μm to 350 μm or 350 μm to 500 μm.

In one embodiment, the polyester resin foam sheet according to the present invention contains potassium carbonate in an appropriate range. The foam sheet can increase the surface uniformity and moldability of the sheet by uniformly mixing and foaming calcium carbonate in the polyester resin.

Specifically, the foam sheet contains 0.5 wt% to 5 wt% of calcium carbonate. The content of the calcium carbonate is in the range of 0.5% to 5% by weight, 1% to 5% by weight, 1.5% to 4.5% by weight or 2% to 3.5% by weight. More specifically, the calcium carbonate may be added in an amount of 1.0 wt% to 3.0 wt% or 3.0 wt% to 4.5 wt%. For example, calcium carbonate (CaCO ₃ ) may have an amorphous shape. For example, calcium carbonate may be introduced into the extruder in the form of a masterbatch. By adding calcium carbonate as described above, a foam sheet having a uniform sheet surface and excellent thermoformability can be manufactured. In addition, since calcium carbonate is uniformly distributed in the polyester resin, the foam sheet obtained by extruding and foaming the resin has high thermal conductivity, so that it is possible to solve the problem of tearing the foam sheet during molding of the foam sheet.

The thermal conductivity of the calcium carbonate may be 1.0 kcal / mh ℃ to 3.0 kcal / mh ℃. Specifically, the thermal conductivity of calcium carbonate may be 1.2 kcal/mh°C to 2.5 kcal/mh°C, 1.5 kcal/mh°C to 2.2 kcal/mh°C, or 1.8 kcal/mh°C to 2.0 kcal/mh°C. More specifically, the thermal conductivity of calcium carbonate may be 1.5 kcal/mh°C to 2.5 kcal/mh°C or 1.8 kcal/mh°C to 2.3 kcal/mh°C. As described above, the foam sheet containing calcium carbonate has a uniform surface by exhibiting excellent thermal conductivity, and can exhibit excellent thermoformability.

The polyester resin according to the present invention may be at least one selected from the group consisting of aromatic and aliphatic polyester resins synthesized from a dicarboxylic acid component and a glycol component or hydroxycarboxylic acid. The polyester resin is, for example, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polylactic acid (PLA), polyglycolic acid (PGA) , polyethylene adipate (Polyehtylene adipate, PEA), polyhydroxyalkanoate (Polyhydroxyalkanoate, PHA), polytrimethylene terephthalate (Polytrimethylene Terephthalate, PTT) and polyethylene naphthalate (Polyethylene naphthalate, PEN) may be at least one selected from the group consisting of have. Specifically, as the polyester resin according to the present invention, polyethylene terephthalate (PET) may be used.

In addition, the present invention provides a method for producing the polyester resin foam described above. In one example, the manufacturing method comprises the steps of: extruding and foaming a polyester resin through an outlet having a ring-shaped cross-section perpendicular to the ejection direction; Partially cooling one side of the extruded and foamed cylindrical sheet; and cutting the extruded and foamed cylindrical sheet in the discharge direction.

In the present invention, before cutting the extruded foamed cylindrical foam sheet, one side of the discharged foam seat is partially cooled. By partially cooling the foam sheet, the foaming ratio is lowered in the area, and the thickness is also reduced. Through this, the present invention can control the thickness and cell size of the foam sheet based on the cross-section in the width direction (TD) of the foam sheet.

In a specific example, in the method for producing the polyester resin foam, in the step of partially cooling one side of the extruded and foamed cylindrical sheet, the step of partially heating the other side of the extruded and foamed cylindrical sheet is performed at the same time it is possible

In the present invention, before cutting the extruded foamed cylindrical foam sheet, one side of the discharged foam sheet is partially cooled, and the other side is partially heated. By partially cooling or heating the foam sheet, the foaming ratio and thickness of the cooled portion are decreased, and the foaming ratio and thickness of the heated portion are increased.

In another example, the manufacturing method comprises the steps of: extruding and foaming a polyester resin through a discharge port having a ring-shaped cross-section perpendicular to the discharge direction; Partially heating one side of the extruded and foamed cylindrical sheet; and cutting the extruded and foamed cylindrical sheet in the discharge direction.

In the present invention, before cutting the extruded foamed cylindrical foam sheet, one side of the discharged foam seat is partially heated. By partially heating the foam sheet, the foaming ratio is increased in the area, and the thickness is also increased. Through this, the present invention can control the thickness and cell size of the foam sheet based on the cross-section in the width direction (TD) of the foam sheet.

In another example, in the manufacturing method of the above-mentioned foam sheet, the step of extruding and foaming the polyester resin is carried out through the step of introducing a polyester resin and calcium carbonate to the extruder and extruding and foaming to prepare a foam sheet And, the content of the calcium carbonate is in the range of 0.5 to 5% by weight. In the present invention, it was confirmed that when a small amount of calcium carbonate was appropriately mixed in the extrusion foaming process, the cell uniformity of the foam sheet was improved, and the surface of the foam sheet was uniformly manufactured. The content of the calcium carbonate is in the range of 0.5 wt% to 5 wt%, specifically, 0.5 wt% to 5 wt%, 1 wt% to 5 wt%, 1.5 wt% to 4.5 wt%, or 2 wt% to 3.5 wt% % range. More specifically, the calcium carbonate may be added in an amount of 1.0 wt% to 3.0 wt% or 3.0 wt% to 4.5 wt%. For example, calcium carbonate (CaCO ₃ ) may have an amorphous shape. For example, calcium carbonate may be introduced into the extruder in the form of a masterbatch. By adding calcium carbonate as described above, a foam sheet having a uniform sheet surface and excellent thermoformability can be manufactured. In addition, since calcium carbonate is uniformly distributed in the polyester resin, the foam sheet obtained by extruding and foaming the resin has high thermal conductivity, so that it is possible to solve the problem of tearing the foam sheet during molding of the foam sheet.

In one example, the calcium carbonate may have an average size of 1 μm to 5 μm. Specifically, the calcium carbonate may have an average size of 1.5 μm to 4 μm, 1.5 μm to 2.5 μm, or 3.5 μm to 4.5 μm. More specifically, the calcium carbonate may have an average size of 1.5 μm to 3.5 μm or 2 μm to 3 μm.

In one example, in the step of introducing the polyester resin into the extruder, the polyester resin may have the form of pellets, granules, beads, chips, and the like, and in some cases It may be introduced into the extruder in the form of a powder.

The polyester resin may be at least one selected from the group consisting of aromatic and aliphatic polyester resins synthesized from a dicarboxylic acid component and a glycol component or hydroxycarboxylic acid. Examples of the polyester resin are as described above.

In the manufacturing method of the foam sheet according to the present invention, the polyester resin and calcium carbonate introduced into the extruder are put into the extruder, melted, and the foam sheet can be manufactured by extrusion foaming. Specifically, a mixture of a polyester resin chip and calcium carbonate may be melted and extruded. For example, the process of melting the polyester resin and calcium carbonate may be performed at a temperature of 260 ℃ to 300 ℃.

In one example, the step of extruding and foaming the resin can be performed using various types of extruders. Extrusion foaming, by continuously extruding and foaming the resin melt, can simplify the process steps and enable mass production.

The manufacturing method of the foam sheet according to the present invention may form an average cell size of the foam sheet in a size of 80 μm to 600 μm. Specifically, the cell size of the foam sheet may be an average of 100 μm to 500 μm, 100 μm to 400 μm, or 350 μm to 500 μm, and more specifically, the cell size of the foam sheet is an average of 200 μm to 350 μm or 350 μm to 500 μm. The average cell size as described above can be formed because calcium carbonate is uniformly mixed with the polyester resin and foamed. Accordingly, the foam seat according to the present invention can improve workability and impact resistance.

In one example, in the step of manufacturing the foam sheet according to the present invention, various types of additives may be added. If necessary, the additive may be added during the fluid connection line or during the foaming process. Examples of the additive, which may have a barrier performance, a hydrophilicity function or a waterproof function, a thickener, a surfactant, a hydrophilic agent, a heat stabilizer, a waterproofing agent, a cell size enlarger, an infrared attenuator, a plasticizer, a fire protection chemical, and at least one functional additive selected from the group consisting of pigments, elastomers, extrusion aids, antioxidants, nucleating agents, antistatic agents and UV absorbers. Specifically, the foam sheet manufacturing method of the present invention may add one or more of a thickener, a nucleating agent, a heat stabilizer, and a foaming agent, and may further include one or more of the functional additives listed above.

For example, the step of preparing the foam sheet of the present invention may include a thickener, a hydrophilic agent, a heat stabilizer, a waterproofing agent, a cell size enlarger, an infrared attenuator, a plasticizer, a fire-fighting chemical, a pigment, an elastic polymer, an extrusion aid, an antioxidant, One or more additives selected from the group consisting of antistatic agents and UV absorbers may be introduced into the fluid connection line. Among the additives required for manufacturing the foam sheet, additives not added in the fluid connection line may 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.

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 heat stabilizer is a commercially available material, and may be phosphoric acid, an alkyl phosphate, or an aryl phosphate. Specifically, the thermal stabilizer in the present invention may be triphenyl phosphate, but is not limited thereto, and as long as it can improve the thermal stability of the resin foam sheet, it can be used without limitation within a conventional range.

As an example of the blowing agent, N ₂ , CO ₂ , Freon, butane, pentane, neopentane, hexane, isohexane, heptane, isoheptane or a physical blowing agent such as methyl chloride may be used. Specifically, in the present invention, butane may be used can

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

Hereinafter, the present invention will be described in more detail by way of Examples and Experimental Examples. However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following Examples and Experimental Examples.

Example One

Based on 100 parts by weight of polyethylene terephthalate (PET) resin, 0.5 parts by weight of pyromellitic dianhydride and 0.1 parts by weight of Irganox (IRG 1010) were mixed, and heated to 280° C. to prepare a resin melt. Then, 1 part by weight of butane as a foaming agent was added to the first extruder based on 100 parts by weight of a polyethylene terephthalate (PET) resin, and extrusion foaming was performed.

1 shows a state in which the foam sheet is discharged by the manufacturing method according to the present embodiment. The resin is extruded and foamed through an annular nozzle having a ring-shaped discharge port cross-section, and a cylindrical foam sheet having an increased diameter is formed in the foaming process. In this embodiment, the cooling member was positioned below the discharged cylindrical foam sheet. Through this, the lower part of the foam sheet is partially cooled, and the foaming ratio is lowered in the area and the cell size is reduced.

A cutting blade is positioned downstream of the extrusion foaming direction of the annular nozzle, and the lower portion of the cylindrical foam sheet is cut in the extrusion foaming direction (MD; Machine Direction). As the bottom of the cylindrical foam sheet is cut, the foam sheet is spread in a plate shape.

A specific cross-section of the nozzle during extrusion foaming is shown in FIG. 2 . Referring to FIG. 2 , based on the cross section of the annular nozzle 100 , the space between the annular outer body 110 and the annular center body 120 forms the annular slot 130 through which the resin is discharged. The annular outer body 110 has a hollow cylindrical shape, and the annular central body 120 is positioned inside the hollow region of the annular outer body 110 . Each center of the annular outer body 110 and the annular center body 120 shares the annular nozzle center (C). The gap between the annular outer body 110 and the annular hollow body 120 acts as a major factor determining the thickness of the foam sheet.

3 shows a cross-section of the foam sheet prepared according to the present embodiment in the TD (traverse direction). Referring to Figure 3, the average thickness of the manufactured foam sheet is 3 mm. In addition, the central region of the foam sheet has a thick thickness and a large cell size, and both ends have a thin thickness and a small cell size. In Figure 3, the minimum thickness (D ₂ ) of the foam sheet is 1.5 mm, the maximum thickness (D ₁ ) of the foam sheet is 3.5 mm.

Example 2

A foam seat was prepared in the same manner as in Example 1, except that the heating member was positioned below the discharged cylindrical foam seat.

4 shows a cross-section of the foam sheet prepared according to the present embodiment in the transverse direction (TD). Referring to Figure 4, the average thickness of the manufactured foam sheet is 3 mm. In addition, the central region of the foam sheet has a thin thickness and a small cell size, and both ends have a thick thickness and a large cell size. In Figure 4, the maximum thickness (D ₁ ) of the foam sheet is 3.5 mm, the minimum thickness (D ₂ ) of the foam sheet is 1.5 mm.

Example 3

A foam sheet was prepared in the same manner as in Example 2, except that 1 wt% of calcium carbonate was mixed with polyethylene terephthalate (PET) resin.

The foam sheet prepared according to Example 3 had a similar cross-sectional shape as compared to the foam sheet according to Example 1, and it was observed that the surface uniformity was improved. The improvement of the surface uniformity means that the surface roughness is reduced.

Example 4

A foam sheet was prepared in the same manner as in Example 1, except that a cooling member was positioned on the upper left side of the discharged cylindrical foam sheet, and a heating member was positioned on the lower right side of the foam sheet.

5 shows a cross-section of the foam sheet prepared according to the present embodiment in the TD (traverse direction). Referring to Figure 5, the average thickness of the manufactured foam sheet is 3.2 mm. In addition, the region on the left from the center of the foam sheet has the thinnest thickness and the smallest cell size, and the region on the right from the center of the foam sheet has the thickest thickness and the largest cell size. 5, the maximum thickness (D ₁ ) of the foam sheet is 3.8 mm, and the minimum thickness (D ₂ ) of the foam sheet is 1.3 mm.

Above, the present invention has been described in more detail with reference to the drawings and examples. However, the configuration described in the drawings or embodiments described in the present specification is only one embodiment of the present invention and does not represent all the technical spirit of the present invention, so at the time of the present application, various equivalents and It should be understood that there may be variations.

100: annular nozzle
110: annular outer body
120: annular center body
130: annular slot
C: center of annular nozzle
D ₁ : Maximum thickness of foam sheet
D ₂ : Minimum thickness of foam sheet

Claims (11)

A polyester resin foam sheet in which 90% or more of cells are closed cells (DIN ISO4590),
The foam sheet,
Based on the width direction (TD) cross section of the foam sheet,
a region having a thickness of D1 and a region having a thickness of D2, wherein the ratio of D1 and D2 is in the range of 5:1 to 1.2:1,
The average cell size (F1) of the region of thickness D1 is larger than the average cell size (F2) of the region of thickness D2, but the average cell size (F1) of the region of thickness D1 and the average cell size of the region of thickness D2 The deviation of (F2) is 20% or more of the polyester resin foam sheet.
The method of claim 1,
The average cell size (F1) of the region having a thickness of D1 (F1) and the average cell size (F2) of the region having a thickness of D2 are the polyester resin foam sheet satisfying Equation 1:
[Formula 1]
20(%) ≤ ((|F _x -F _mean |)/F _mean )x100 ≤ 90(%)
In Equation 1,
F _x represents the value of F1 or F2,
F _mean represents the average value of the numerical values of F1 and F2.
The method of claim 1,
The region of thickness D1 is
the average thickness (D1) ranges from 1.5 mm to 5 mm,
A polyester resin foam sheet having an average cell size (F1) in the range of 150 to 650 μm.
The method of claim 1,
The region of thickness D2 is
the average thickness (D2) ranges from 0.5 mm to 3 mm,
A polyester resin foam sheet having an average cell size (F1) in the range of 50 to 250 μm.
The method of claim 1,
Polyester resin foam sheet, characterized in that the cell size of the foam sheet is an average of 80 ㎛ to 600 ㎛.
The method of claim 1,
The foam sheet is a polyester resin foam sheet containing 0.5 wt% to 5 wt% of calcium carbonate.
The method of claim 1,
The polyester resin is a polyester resin foam sheet, characterized in that the polyethylene terephthalate resin.
Extruding and foaming a polyester resin through an outlet having a ring-shaped cross-section perpendicular to the ejection direction;
Partially cooling one side of the extruded and foamed cylindrical sheet; and
A method for producing a polyester resin foam sheet comprising the step of cutting the extruded and foamed cylindrical sheet in the discharge direction.
9. The method of claim 8,
In the step of partially cooling one side of the extruded and foamed cylindrical sheet,
A method for producing a polyester resin foam sheet, characterized in that simultaneously performing the step of partially heating another side of the extruded and foamed cylindrical sheet.
Extruding and foaming a polyester resin through an outlet having a ring-shaped cross-section perpendicular to the ejection direction;
Partially heating one side of the extruded and foamed cylindrical sheet; and
A method for producing a polyester resin foam sheet comprising the step of cutting the extruded and foamed cylindrical sheet in the discharge direction.
11. The method of claim 8 or 10,
The step of extruding and foaming the polyester resin,
It is carried out through the step of introducing a polyester resin and calcium carbonate to the extruder and extruding and foaming to prepare a foam sheet,
The content of the calcium carbonate is a method for producing a polyester resin foam sheet in the range of 0.5 wt% to 5 wt%.

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