KR102313714B1 - Polyester foam sheet comprising inorganic particles with different average diameters - Google Patents

Abstract

The present invention is a polyester foam sheet in which inorganic particles including a first group of calcium carbonate particles and a second group of calcium carbonate particles having different average particle diameters are dispersed in a polyester resin matrix, and the sheet surface is uniform to reduce the occurrence of wrinkles can do it

Description

Polyester foam sheet containing inorganic particles with different particle sizes {POLYESTER FOAM SHEET COMPRISING INORGANIC PARTICLES WITH DIFFERENT AVERAGE DIAMETERS}

The present invention relates to a polyester foam sheet in which inorganic particles having different particle diameters are dispersed in a polyester resin.

Polyester resins with crystallinity such as polyethylene terephthalate (PET) have superior mechanical properties compared to polyethylene-based resins or polypropylene-based resins, and have excellent heat resistance and chemical resistance, and are used in various fields requiring light weight and high physical properties. This is possible. Polyester resin has excellent mechanical and chemical properties, so it can be used for multi-purpose applications, for example, conventionally for drinking water containers and medical, food packaging, food containers, sheets, films, automobile molded products, etc. applications are being made in the field of

In particular, a foam sheet containing a polyester resin has a foaming layer composed of a resin composition containing a polyester resin, so it is excellent in light weight and strength, so that it can be used as a sheet-shaped molded article as it is, and three-dimensional such as thermoforming It can be molded into a molded body having a typical shape.

However, the foam sheet containing the polyester resin has the above-mentioned high rigidity, which is excellent in lightness and strength, so it is difficult to give a desired shape by thermoforming or the like, and there is a disadvantage in that it is easily broken. In addition, since a process such as thermoforming is included when a foam sheet is commercialized, the thermal properties of the polyester resin act as a very important factor.

An object of the present invention is to provide a polyester foam sheet in which inorganic particles comprising a first group of calcium carbonate particles and a second group of calcium carbonate particles having different average particle diameters are dispersed in a polyester resin.

A polyester foam sheet according to an embodiment of the present invention is a polyester foam sheet in which inorganic particles containing an alkaline earth metal carbonate are dispersed in a polyester resin, wherein the inorganic particles include a first group of calcium carbonate particles having an average particle diameter of D1; and a second group of calcium carbonate particles having a D2 average particle size, wherein the ratio of the first group of calcium carbonate particles to the second group of calcium carbonate particles is in the range of 1.1:1 to 1:5 by weight, and the D1 average particle size and the D2 The relationship between the average particle diameter is a polyester foam sheet that satisfies the following formula.

[Equation]

1.2 ≤ (D2-D1)/D1 ≤ 2.1

Here, the D1 average particle diameter of the first calcium carbonate particle group may be 1 to 4 μm, and the D2 average particle diameter of the second calcium carbonate particle group may be 4 to 8 μm.

The alkaline earth metal carbonate may be an inorganic carbonate containing at least one cation selected from the group consisting of Ca, Mg and Ba.

The polyester foam sheet has an average thickness of 1 to 10 mm, and an average foaming density according to KS M ISO 845:2012 may be ^{100 to 600 kg/m 3 .}

In addition, the cell size of the foam sheet may be an average of 100 μm to 700 μm.

The polyester may be polyethylene terephthalate (PET).

The content of the inorganic particles may be in the range of 0.5 to 5% by weight.

In the polyester foam sheet, the number of wrinkles formed per unit area of 10 cm in width and 10 cm in length may be two or less when evaluating reliability for surface uniformity.

In the polyester foam sheet according to the present invention, as inorganic particles comprising a first group of calcium carbonate particles and a group of second calcium carbonate particles having different average particle diameters are dispersed, the cell size of the foam sheet can be reduced and the density can be increased, , it is possible to reduce the occurrence of corrugation because the sheet surface is uniform.

Since the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It is to be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof. Also, terms such as first and second may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. The singular expression includes the plural expression unless the context clearly dictates otherwise.

Hereinafter, embodiments of the present invention will be described in more detail.

The polyester foam sheet according to an embodiment of the present invention is a polyester foam sheet in which inorganic particles containing alkaline earth metal carbonate are dispersed in a polyester resin. The foam sheet can improve the surface uniformity and moldability of the sheet by uniformly mixing and foaming inorganic particles with the polyester resin.

In one embodiment, the inorganic particles include a first group of calcium carbonate particles having an average particle diameter of D1; and a second group of calcium carbonate particles having an average particle diameter of D2. In this case, the ratio of the first calcium carbonate particle group to the second calcium carbonate particle group may be in the range of 1.1:1 to 1:5 by weight, for example, 1:1 to 1:4, 1:1.5 to 1:4, 1:1.5 to 1:3, 1:1.3 to 1:2.

In addition, the relationship between the D1 average particle diameter of the first calcium carbonate particle group and the D2 average particle diameter of the second calcium carbonate particle group satisfies the following formula.

[Equation]

1.2 ≤ (D2-D1)/D1 ≤ 2.1

For example, (D2-D1)/D1 may be 1.3 to 2.0, 1.2 to 1.8, 1.5 to 2.0, or 1.3 to 1.7.

In a specific example, the D1 average particle diameter of the first group of calcium carbonate particles is in the range of 1 to 4 μm. The D1 average particle diameter of the first group of calcium carbonate particles may be, for example, 1.3 to 3 μm, 1.5 to 3 μm, 1.8 to 3.2 μm, and 2 to 3.5 μm.

In addition, the D2 average particle diameter of the second calcium carbonate particle group is in the range of 4 to 8 μm. The D2 average particle diameter of the second calcium carbonate particle group may be, for example, 4.5 to 8 μm, 4.8 to 7.8 μm, 5 to 7 μm, and 4 to 7 μm.

In one embodiment, the alkaline earth metal element is at least one selected from the group consisting of calcium (Ca), magnesium (Mg) and barium (Ba). For example, the inorganic particles may be calcium carbonate (CaCO ₃ ), and the calcium carbonate may have an amorphous shape.

The thermal conductivity of the inorganic particles may be 1.0 kcal/mh°C to 3.0 kcal/mh°C. Specifically, the thermal conductivity of the inorganic particles is 1.2 kcal/mh°C to 2.5 kcal/mh°C, 1.5 kcal/mh°C to 2.2 kcal/mh°C, 1.8 kcal/mh°C to 2.0 kcal/mh°C, 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 including the inorganic particles has a uniform surface by exhibiting excellent thermal conductivity and can exhibit excellent thermoformability.

In one embodiment, the foam sheet according to the present invention includes calcium carbonate, which is an inorganic particle containing an alkaline earth metal carbonate in an appropriate range. The foam sheet can increase the surface uniformity and moldability of the sheet by uniformly mixing and foaming inorganic particles in the polyester resin.

Specifically, the foam sheet contains 0.5 wt% to 5 wt% of inorganic particles. The content of the inorganic particles is in the range of 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%. 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%.

On the other hand, the polyester resin may include an aromatic or aliphatic polyester resin synthesized from a dicarboxylic acid component, a glycol component, or hydroxycarboxylic acid. Non-limiting examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polylactic acid (PLA), polyglycolic acid (PGA). ), polyethylene adipate (Polyehtyleneadipate, PEA), polyhydroxyalkanoate (Polyhydroxyalkanoate, PHA), polytrimethylene terephthalate (Polytrimethylene Terephthalate, PTT) and polyethylene naphthalate (Polyethylene naphthalate, PEN) may be more than Specifically, polyethylene terephthalate may be used as the polyester resin.

The polyester resin may have an intrinsic viscosity (IV) of 0.4 dl/g to 1.2 dl/g. Specifically, the intrinsic viscosity is 0.5 dl/g to 1.1 dl/g, 0.6 dl/g to 1.0 dl/g, 0.7 dl/g to 1.1 dl/g, 0.9 dl/g to 1.1 dl/g, 0.5 dl/g to 0.7 dl/g, 0.6 dl/g to 0.7 dl/g, 0.7 dl/g to 0.9 dl/g, 0.75 dl/g to 0.85 dl/g, 0.77 dl/g to 0.83 dl/g or 0.6 dl/g to It may be 0.8 dl/g.

The average density according to KS M ISO 845:2012 of the manufactured foam sheet is 100 to 600 kg/m ³ , 100 to 500 kg/m ³ , 100 to 400 kg/m ³ , 100 to 300 kg/m ³ , 100 to 200 kg/m ³ , 200 to 600 kg/m ³ , 300 to 600 kg/m ³ , 400 to 600 kg/m ³ , or 500 to 600 kg/m ³ .

In addition, the average thickness of the foam sheet may be in the range of 1.0 to 10.0 mm. For example, the average thickness of the foam sheet is 1.0 to 5.0 mm, 1.0 to 4.0 mm, 1.0 to 3.5 mm, 1.0 to 3.0 mm, 1.0 to 5.5 mm, 1.0 to 2.0 mm, 1.0 to 1.5 mm, 1.5 to 5.0 mm , 2.0 to 5.0 mm, 3.0 to 5.0 mm, or 4.0 to 5.0 mm.

In one embodiment, the cell size of the foam sheet ranges on average from 100 μm to 700 μm. Specifically, the cell size of the foam sheet may be an average of 100 μm to 600 μm, 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 foam sheet may have an evaluation grade of 2 or less in a unit area when evaluating reliability for surface uniformity. For example, in the reliability evaluation of the surface uniformity, the foam sheet was cut to 10 cm in width and 10 cm in length, and the number of wrinkles present on the cut sheet was counted, and the counted number of wrinkles was determined by the following criteria. It may be classified according to the grade and evaluated (Grade 1: When the number of wrinkles is 0 / Grade 2: When the number of wrinkles is more than 0 and less than 2 / Grade 3: The number of wrinkles is more than 2 and less than 4 or less / Grade 4: When the number of wrinkles is more than 4 and less than or equal to 10 / Grade 5: When the number of wrinkles is more than 10). For example, the number of wrinkles in the foam sheet may be two or less per unit area.

The foam sheet according to the present invention includes alkaline earth metal carbonate as inorganic particles, and the inorganic particles include a first group of calcium carbonate particles and a second group of calcium carbonate particles having different average particle diameters, so that the size of the cells of the foam sheet is reduction, the density can be increased, and the occurrence of corrugation can be reduced because the sheet surface is uniform.

The manufacturing method of the foam sheet according to one embodiment may include the step of injecting the polyester resin and calcium carbonate introduced into the extruder into the extruder and melting and extruding the foam sheet to prepare the foam sheet. 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 inorganic particles containing the alkaline earth metal carbonate may be mixed with a polyester resin in the form of a masterbatch to prepare a resin melt.

In addition, 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, etc., in which case Accordingly, it may be introduced into the extruder in the form of a powder.

The temperature of the extruded foam sheet may be in the range of 220 to 270 ℃. The temperature of the extruded foamed sheet refers to the temperature of the extruded foamed sheet between the extrusion die and the mandrel of the foaming device when extruding and foaming the resin melt foam sheet using a foaming device. can For example, the temperature of the extruded foam sheet may be 220 to 250 ℃, 220 to 230 ℃, 230 to 270 ℃, or 250 to 270 ℃.

By including the alkaline earth metal carbonate as described above, the size of the cells of the foam sheet can be reduced, the density can be increased, and the sheet surface can be uniform to reduce the occurrence of wrinkles and exhibit excellent thermoformability. . 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 alkaline earth metal element may be an inorganic carbonate containing at least one cation selected from the group consisting of Ca, Mg, and Ba. Specifically, the inorganic particles containing the alkaline earth metal carbonate may include calcium carbonate (CaCO3), magnesium carbonate (MgCO3), and barium carbonate (BaCO3), and more specifically, the inorganic particles of the present invention include calcium carbonate may include

In one embodiment, the inorganic particles include a first group of calcium carbonate particles having an average particle diameter of D1; and a second group of calcium carbonate particles having an average particle diameter of D2. In this case, the ratio of the first calcium carbonate particle group to the second calcium carbonate particle group may be in the range of 1.1:1 to 1:5 by weight, for example, 1:1 to 1:4, 1:1.5 to 1:4, 1:1.5 to 1:3, 1:1.3 to 1:2.

In addition, the relationship between the D1 average particle diameter of the first calcium carbonate particle group and the D2 average particle diameter of the second calcium carbonate particle group satisfies the following formula.

[Equation]

1.2 ≤ (D2-D1)/D1 ≤ 2.1

For example, (D2-D1)/D1 may be 1.3 to 2.0, 1.2 to 1.8, 1.5 to 2.0, or 1.3 to 1.7.

In a specific example, the D1 average particle diameter of the first group of calcium carbonate particles is in the range of 1 to 4 μm. The D1 average particle diameter of the first group of calcium carbonate particles may be, for example, 1.3 to 3 μm, 1.5 to 3 μm, 1.8 to 3.2 μm, and 2 to 3.5 μm.

In addition, the D2 average particle diameter of the second calcium carbonate particle group is in the range of 4 to 8 μm. The D2 average particle diameter of the second calcium carbonate particle group may be, for example, 4.5 to 8 μm, 4.8 to 7.8 μm, 5 to 7 μm, and 4 to 7 μm.

The manufacturing method of the polyester foam sheet according to the present invention, by performing a process of post-foaming by heat-treating the polyester foam sheet, the phenomenon of post-foaming due to a low volume change rate when heat is applied when working using the polyester foam sheet It can be prevented, and as the thickness of the polyester foam sheet becomes thicker by post-foaming, the degree of crystallinity increases, and the flexural strength can be increased.

In the heat treatment step of the extruded foamed polyester foam sheet, the surface temperature and heat treatment time of the foam sheet according to the heat treatment may affect the thickness of the polyester foam sheet, and by heat treatment in the heat treatment temperature and time range according to the present invention It is possible to improve the crystallinity, heat resistance and flexural strength of the polyester foam sheet.

The heat treatment of the extruded foamed polyester foam sheet may be a heat treatment for 30 to 200 seconds, for example, the heat treatment is 30 to 200 seconds, 30 to 150 seconds, 30 to 100 seconds, 30 to 50 Seconds, 50 to 200 seconds, 100 to 200 seconds, or may be performed for 150 to 200 seconds.

The step of heat-treating the extruded foamed polyester foam sheet may be to prepare a polyester foam sheet having a surface temperature of 120 to 250 ° C. by heat treatment, for example, the surface temperature is 120 to 250 ° C., 120 to 230 °C, 120 to 200 °C, 120 to 180 °C, 120 to 160 °C, 120 to 140 °C, 140 to 250 °C, 160 to 250 °C, 180 to 250 °C, 200 to 250 °C, or 230 to 250 °C can

Heating the extruded foamed polyester foam sheet may include direct heat treatment and indirect heat treatment methods, for example, direct heat treatment may be to apply heat directly to the surface of the foam sheet, indirect heat treatment is heat treatment It may be to apply heat by controlling the temperature of the atmosphere.

The direct heat treatment may be to heat the surface temperature of the extruded foamed polyester foam sheet to a temperature of 120 to 300 ℃. For example, the surface temperature of the extruded foamed polyester foam sheet may be heated to 120 to 300 ℃, 120 to 200 ℃, 120 to 150 ℃, 150 to 300 ℃, or 200 to 300 ℃ temperature.

Heat treatment by contacting one or both surfaces of the extruded foamed polyester foam sheet to heat the surface temperature of the extruded foamed polyester foam sheet to a temperature of 120 to 300° C., the heating plate temperature is the polyester foam sheet The temperature for heating one or both sides of the may be in the range of 100 to 300 ℃, 100 to 250 ℃, 100 to 200 ℃, 100 to 150 ℃, 150 to 300 ℃, 200 to 300 ℃, 250 to 300 ℃.

The indirect heat treatment, the step of heat treatment of the extruded foamed polyester foam sheet, may be heat treatment in an atmosphere of 120 to 600 ℃. For example, the extruded foamed polyester foam sheet is heat-treated in an atmosphere of 120 to 600 ℃, 120 to 400 ℃, 120 to 200 ℃, 150 to 600 ℃, 200 to 600 ℃, or 400 to 600 ℃ atmosphere. It may be to heat the surface temperature of the polyester foam sheet to a temperature of 120 to 300 ℃.

When the heat treatment temperature of the extruded foamed polyester foam sheet according to the present invention is in the above range, it may be easy to post-foam the extruded foamed polyester foam sheet by 1.5 to 3 times.

The expansion ratio after heat treatment of the extruded foamed polyester foam sheet may be 1.5 to 3 times the expansion ratio before heat treatment. The heat treatment may be to perform post-foaming of the extruded foamed polyester foam sheet, and may be foamed 1.5 to 3 times more than the expansion ratio before post-foaming (heat treatment).

The average thickness of the polyester foam sheet may be 1.5 to 10 mm. The average thickness of the polyester foam sheet may be increased by 1.5 to 2 times than before the heat treatment of the extruded polyester foam sheet, for example, the average thickness of the polyester foam sheet is 1.5 to 10 mm, 1.5 to 8 mm , 1.5 to 5 mm, 5 to 10 mm, or 7.5 to 10 mm.

By going through the step of heat-treating the extruded foamed polyester foam sheet, the expansion ratio of the polyester foam sheet is increased. can do.

For example, the extruded foamed polyester foam sheet can be heat-treated (post-foamed) by being heated while passing a heater by a conveyor belt, and the extruded foamed polyester foam sheet is a nip roller holding the front and rear ends in parallel (Nip Roller) can be heated as it passes through the heater and heat-treated (post-foaming).

After the heat treatment of the extruded foamed polyester foam sheet, it may be further subjected to a step of cooling the polyester foam sheet. The cooling step may be cooled by a cooling roller while the polyester foam sheet is moved by a conveyor belt. At this time, the cooling step may be performed to harden the portion where the polyester foam sheet was molten by heat treatment, and to prevent distortion of the shape of the polyester foam sheet.

As an example, the temperature of the cooling roller in the cooling step is 15 ° C or less, 1 to 14.5 ° C, 1.5 to 14 ° C, 2 to 13.5 ° C ¸ 2.5 to 13 ° C, 3 to 12.5 ° C, 3.5 to 12 ° C, 4 to 11.5°C or 4.5 to 10°C.

After the heat treatment of the extruded foamed polyester foam sheet, the step of cutting the polyester foam sheet at regular intervals may be further processed. The cutting step may be cut by a cutter while the polyester foam sheet is moved by a conveyor belt.

In addition, in the cutting step, after heat treatment of the extruded foamed polyester foam sheet, the polyester foam sheet is cooled through a cooling roller while moving by a conveyor belt, and then it can be cut by a cutter while moving by a conveyor belt.

The manufacturing method of the polyester foam sheet according to the present invention has the advantage of improving processability and facilitating mass production by performing a process of cutting the heat-treated extruded foamed polyester foam sheet by a cutter.

As an 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-fighting 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, in the present invention, the thermal stabilizer 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.

Examples of the blowing agent include physical blowing agents such as N2, CO2, Freon, butane, pentane, neopentane, hexane, isohexane, heptane, isoheptane, and methyl chloride. Specifically, butane may be used in the present invention. .

In addition, the waterproofing agent is not particularly limited, 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 polyol and polyurethane resin, a mixture series of acrylic polymer and polyurethane resin, polyimide series, and a mixture series of cyanoacrylate and urethane.

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

[Examples 1 to 3]

In order to prepare the polyester foam sheet, first, 100 parts by weight of a polyethylene terephthalate (PET) resin having a melting point of 245° C. was dried at 180° C. to remove moisture, and based on 100 parts by weight of the PET resin from which moisture was removed in the extruder, fatigue 5 parts by weight of mellitic dianhydride (PMDA), 0.1 parts by weight of a heat stabilizer (Iganox 1010) and calcium carbonate were mixed, and heated to 280° C. to prepare a resin melt. At this time, as the calcium carbonate, a group of first calcium carbonate particles having an average particle diameter of D1 and a group of second calcium carbonate particles having an average particle diameter of D2 were used, and the average particle diameter, weight ratio and content of each Example were adjusted as shown in Table 1 below.

Then, 1.5 parts by weight of butane as a foaming agent was added to the extruder based on 100 parts by weight of PET resin, and the resin melt was cooled to 250±2°C. The cooled resin melt was extruded and foamed while passing through a die.

[Comparative Examples 1 and 2]

Foam sheets were each prepared in the same manner as in Example 1, except that the average particle diameter and content of calcium carbonate were adjusted as shown in Table 1 below.

Total content of inorganic particles
(parts by weight) D1 D2 Average particle size (㎛) weight ratio Average particle size (㎛) weight ratio Example 1 3.1 1.5 55% 4.5 45% Example 2 3.1 2.0 45% 6.0 55% Example 3 3.1 3.0 50% 7.0 50% Comparative Example 1 3.1 1.5 90% 4.5 10% Comparative Example 2 3.1 2.0 10% 6.0 90%

[Experimental example]

In order to evaluate the physical properties of the foam sheet according to Examples and Comparative Examples, the following experiments were performed, and the results are shown in Table 2 below.

1) Measurement of average thickness and expansion ratio of foam sheet (density measurement)

In order to measure the average thickness of each foam sheet, the entire width of each foam sheet was divided into 8 at regular intervals and the thickness was measured using an indicator (ID-C112, Mitutoyo Corporation), and then the average value was calculated.

In addition, in order to measure the average foaming density of each foam sheet, a sample was taken for each foam sheet with a width of 2 cm Х length of 2 cm, and then the foaming density was measured with an underwater electron density meter (EW300SG, MIRAGE Corporation).

2) Uniformity evaluation

In order to evaluate the reliability of each foam sheet, specifically, the shape uniformity of the extruded foam sheet, each foam sheet was cut to 10 cm wide and 10 cm long, and the number of wrinkles present on the cut sheet was counted and counted. The grades were evaluated by classifying the number of wrinkles according to the following criteria.

Grade 1: When the number of wrinkles is 0

Grade 2: When the number of wrinkles is more than 0 and less than 2

Grade 3: When the number of wrinkles is more than 2 but less than 4

Grade 4: When the number of wrinkles is greater than 4 and less than or equal to 10

Grade 5: When the number of wrinkles is more than 10

Thickness (mm) Density (kg/m ³ ) Wrinkles (ea) Example 1 1.0 350 0 (Level 1) Example 2 2.0 350 0 (Level 1) Example 3 2.2 350 0 (Level 1) Comparative Example 1 1.0 350 No firing Comparative Example 2 2.0 350 20 (Level 5)

As can be seen from Table 1, the polyester foam sheet according to the embodiment is wrinkled in the manufacturing process according to the average particle diameter and weight ratio of each of the first calcium carbonate particle group and the second calcium carbonate particle group in an appropriate range. I could confirm that it wasn't.

On the other hand, the foam sheet according to Comparative Example 1 contained a large amount of inorganic particles of small particle diameter, and thus did not foam itself due to insufficient role of nuclei. In addition, the foam seat according to Comparative Example 2 contained a large amount of inorganic particles having a large particle diameter, and as a result, it was confirmed that a number of wrinkles occurred in the sheet during the foaming process.

Claims (8)

As a polyester foam sheet in which calcium carbonate particles are dispersed in polyethylene terephthalate (PET) resin,
The calcium carbonate particles include a first group of calcium carbonate particles having an average particle diameter of D1; and a second group of calcium carbonate particles having an average particle diameter of D2,
The ratio of the first calcium carbonate particle group to the second calcium carbonate particle group is in the range of 1.1:1 to 1:5 weight ratio,
The relationship between the D1 average particle diameter and the D2 average particle diameter satisfies the following equation,
When evaluating the reliability of the surface uniformity, the polyester foam sheet having 2 or less wrinkles per unit area of 10 cm in width and 10 cm in length:
[Equation]
1.2 ≤ (D2-D1)/D1 ≤ 2.1
In the above formula, D2 is in the range of 4 to 8 μm.
According to claim 1,
D1 average particle diameter of the first calcium carbonate particle group is 1.5 to 3㎛ polyester foam sheet.
According to claim 1,
The average thickness is 1 to 10mm, and the average foaming density according to KS M ISO 845:2012 is 100 to 600 kg/m ³ Polyester foam sheet.
According to claim 1,
The cell size of the foam sheet is an average of 100 μm to 700 μm polyester foam sheet.
According to claim 1,
The content of the calcium carbonate particles is a polyester foam sheet in the range of 0.5 to 5% by weight. delete delete delete