JP7181932B2 - Polyester foam sheet and its manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyester foam sheet and a method for producing the polyester foam sheet.

As the quality of life improves, there is a demand for the development of useful materials that can simultaneously satisfy physical properties such as weight reduction and durability in various industrial fields such as construction, automobiles, and food. Among them, for example, in the field of automobile industry, many efforts are being made to reduce the weight of automobiles in order to save fuel consumption of automobiles. Among them, weight reduction of automotive interior materials such as trunk partition, luggage side, headliner, package tray, ceiling, bottom, door trim, trunk trim, etc. Various developments are underway for this purpose, and much effort has been made to reduce the cost of manufacturing interior materials for automobiles by improving moldability and shortening the process when manufacturing interior materials. is doing.

Conventionally, as a method for improving the durability and strength of automobile interior materials, a sheet formed by mixing polyurethane (PU) and glass fiber is used, or polypropylene (PP) is mixed with glass fiber. LWRT (low weight reinforced thermoplastics), which is a sheet-shaped material molded by heating, is mainly used.

However, in the case of materials containing glass fibers as described above, there is a problem that a large amount of dust is generated by the glass fibers during work, which deteriorates the health of workers and the working environment.

Therefore, by not mixing glass fiber, it solves the problem of dust generation during operation, satisfies durability and strength quality, and reduces weight, making it possible to reduce weight, which is useful in various industrial fields. There is an urgent need for the development of composite sheets that can be used for

An object of the present invention is to provide a polyester foam sheet and a method for producing the polyester foam sheet.

In order to solve the above problems,
The present invention provides, in one embodiment,
Provided is a polyester foam sheet having a volume change rate of 5% or less after being maintained at 150° C. for 6 hours, and a crystallinity of 15 to 30%.

Moreover, in one embodiment of the present invention,
Provided is a method for producing a polyester foam sheet, comprising the step of heat-treating an extruded polyester foam sheet at 120-600° C. for 30-200 seconds.

The polyester foam sheet according to the present invention is subjected to a post-foaming process by heat-treating the polyester foam sheet, so that the volume change rate is low when heat is applied during the work using the polyester foam sheet, resulting in post-foaming phenomenon. As the thickness of the polyester foam sheet increases by 1.5 to 2 times due to post-foaming, the degree of crystallinity increases and the bending strength increases.

The polyester foam sheet according to the present invention can be applied to bulkheads inside ships, sandwich panel core materials used for building exterior materials, MDF (medium density fiberboard) substitute materials for furniture, interior and exterior materials for automobiles, and the like.

FIG. 1 schematically shows the manufacturing process of the polyester foam sheet according to the present invention.

Since the present invention can be modified in various ways and has various embodiments, specific embodiments will be illustrated in the drawings and will be described in detail in the detailed description.

However, this is not intended to limit the invention to any particular embodiment, but should be understood to include all modifications, equivalents or alternatives falling within the spirit and scope of the invention. not.

In the present invention, terms such as "including" or "having" are intended to specify the presence of the features, figures, steps, acts, components, parts, or combinations thereof set forth in the specification. without precluding the possibility of the presence or addition of one or more other features, figures, steps, acts, components, parts or combinations thereof.

The present invention will be specifically described below.

The present invention provides a polyester foam sheet having a volume change rate of 5% or less and a crystallinity of 15 to 30% after being maintained at 150° C. for 6 hours.

Since the polyester foam sheet includes a polyester foam sheet post-foamed by secondary foaming after primary foaming, the volume change rate may be 5% or less even after long-term heat treatment. For example, the volume change rate is 0.1 to 5%, 0.1 to 4%, 0.1 to 3%, 0.1 to 2%, 0.1 to 1%, 1 to 5%, 2 to It can be 5%, 3-5%, or 4-5%.

The polyester foam sheet may have a crystallinity of 15-30%, 15-25%, 15-20%, 20-30%, or 25-30%. For example, when the crystallinity of the polyester foam sheet is 15% or less, the bending strength may be low due to the low crystallinity. Due to the high degree of hardness, the moldability of the foam sheet is low, and it may not be possible to mold the desired shape.

The polyester foam sheet of the present application is subjected to a step of heat-treating the polyester foam sheet and post-foaming so that the volume change rate and crystallinity of the polyester foam sheet satisfy the above ranges, so that the polyester foam sheet can be used during work. Since the volume change rate is low when heat is applied, the phenomenon of post-foaming can be prevented. , the bending strength is increased.

The polyester foam sheet according to the present invention can be applied to bulkheads inside ships, sandwich panel core materials used for building exterior materials, MDF (medium density fiberboard) substitute materials for furniture, interior and exterior materials for automobiles, and the like.

For example, when the crystallinity of the polyester foam sheet satisfies the above range, the bending strength of the resin foam according to KS M ISO 844 of the polyester foam sheet may be 5 to 30 N/cm ² . For example, the bending strength of the resin foam according to KS M ISO 844 of the polyester foam sheet is 5 to 30 N/cm ² , 5 to 20 N/cm ² , 5 to 15 N/cm ² , 10 to 30 N/cm 2 , 20 to 30 N/cm ² . It can be 30 N/cm ² .

The density of the polyester foam sheet according to KS M ISO 845 may be 50-350 kg/m ³ . For example, the density according to KS M ISO 845 of the polyester foam sheet is 50-350 kg/m ³ , 50-300 kg/m ³ , 50-250 kg/m ³ , 50-200 kg/m ³ , 50-100 kg/m ³ , It can be 100-350 kg/m ³ , 200-350 kg/m ³ , or 300-350 kg/m ³ .

Specific examples of polyesters that can be used in the present invention include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polylactic acid (PLA), polyglycolic acid acid, PGA), Polypropylene (PP), Polyethylene (PE), Polyethylene adipate (PEA), Polyhydroxyalkanoate (PHA), Polytrimethylene terephthalate (PolytrimethyleneT) and polyethylene, PTHALATE It may be one or more selected from the group consisting of naphthalene (polyethylene naphthalate, PEN).

Specifically, the polyester foam sheet in the present invention may be a polyethylene terephthalate (PET) foam sheet.

The polyester foam sheet may have 90% or more closed cells (DIN ISO4590). This means that 90% or more of the cells of the polyester resin foam sheet measured according to DIN ISO 4590 are closed cells. For example, closed cells of the polyester foam sheet may be 90-100% or 95-100%.

The polyester foam sheet according to the present invention can provide a foam sheet that satisfies excellent lightness, durability and rigidity by having closed cells within the above range. For example, the number of cells of the polyester foam sheet can include 1-30 cells, 3-25 cells, or 3-20 cells per mm ² .

Also, the average size of the cells may range from 100 to 800 μm. For example, the average size of the cells can range from 100-700 μm, 200-600 μm, or 300-600 μm. At this time, the cell size deviation may be, for example, in the range of 5% or less, 0.1 to 5%, 0.1 to 4%, 0.1 to 3%, or 0.1 to 1%. As a result, it can be seen that the polyester foam sheet according to the present invention has uniformly expanded cells of uniform size.

The polyester foam sheet may have an average thickness of 1.0 to 10 mm. For example, the polyester foam sheet may have an average thickness of 1.0-10 mm, 1.0-8 mm, 1.0-5 mm, 5-10 mm, or 7.5-10 mm.

The polyester foam sheet according to the present invention may have a hydrophilic function, a waterproof function, a flame retardant function, or an ultraviolet blocking function, and may include surfactants, hydrophilic agents, flame retardants, heat stabilizers, cell size enlarging agents, and infrared attenuation. one or more functional additives selected from the group consisting of additives, plasticizers, fire retardant chemicals, pigments, elastomeric polymers, extrusion aids, antioxidants, nucleating agents, anti-skid agents and UV absorbers. be able to. Specifically, the polyester foam sheet of the present invention may contain thickeners, nucleating agents, heat stabilizers and foaming agents. Although the thickening agent is not particularly limited, pyromellitic dianhydride (PMDA) can be used in the present invention, for example.

Examples of the nucleating agent include talc, mica, silica, diatomaceous earth, alumina, titanium oxide, zinc oxide, magnesium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, potassium carbonate, calcium carbonate, magnesium carbonate, sulfuric acid. Inorganic compounds such as potassium, barium sulfate, sodium bicarbonate, and glass beads are included. Such a nucleating agent can play a role in imparting functionality to the polyester foam sheet and reducing costs. Specifically, talc may be used in the present invention.

The thermal stabilizer can be an organic or inorganic phosphorus compound. Said organic or inorganic phosphorus compounds can be, for example, phosphoric acid and its organic esters, phosphorous acid and its organic esters. For example, the heat stabilizer is a commercially available substance and can be phosphoric acid, alkyl phosphate or aryl phosphate. Specifically, the thermal stabilizer in the present invention may be triphenyl phosphate, but is not limited to this, and is usually triphenyl phosphate as long as it can improve the thermal stability of the polyester foam sheet. can be used without restrictions within the scope of

Examples of the blowing agent include physical blowing agents such as N ₂ , CO ₂ , freon, butane, pentane, neopentane, hexane, isohexane, heptane, isoheptane, methyl chloride or azodicarbonamide-based compounds, P ,P'-oxybis(benzenesulfonyl hydrazide) [P,P'-oxy bis(benzene sulfonyl hydrazide)] based compounds, N,N'-dinitrosopentamethylenetetramine (N,N'-dinitroso pentamethylene tetramine) based compounds There are chemical blowing agents such as CO2, and in particular _CO2 may be used in the present invention.

The flame retardant may include, but is not limited to, for example, bromine compounds, phosphorus or phosphorus compounds, antimony compounds. Bromine compounds include, for example, tetrabromobisphenol A and decabromodiphenyl ether; phosphorus or phosphorus compounds include aromatic phosphates, aromatic condensed phosphates, halogenated phosphates and red phosphorus; Compounds can include antimony trioxide and antimony pentoxide, and the like.

The surfactant is not particularly limited, and anionic surfactants (e.g., fatty acid salts, alkyl sulfate salts, alkylbenzene sulfonates, alkyl naphthalene sulfonates, alkyl sulfosuccinates, polyoxyethylene alkyl sulfate 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, alkylalkanolamides, etc.), cationic and zwitterionic surfactants (e.g., 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 copolymers, polyacrylamides, polyacrylic acids, polyacrylates, sodium alginate, polyvinyl alcohol moieties saponified products, etc.).

In addition, the present invention provides a method for producing a polyester foam sheet, which includes heat-treating an extruded polyester foam sheet at 120-600° C. for 30-200 seconds.

In the method for producing a polyester foam sheet according to the present invention, the process of heat-treating the polyester foam sheet and post-foaming is performed. In addition, as the thickness of the polyester foam sheet increases due to post-foaming, the degree of crystallinity increases and the bending strength increases.

In the heat treatment step of the extruded polyester foam sheet, the surface temperature and heat treatment time of the heat-treated foam sheet can affect the thickness of the polyester foam sheet. Heat treatment can improve the crystallinity, heat resistance and bending strength of the polyester foam sheet.

The step of heat-treating the extruded polyester foam sheet may be heat-treating for 30-200 seconds, for example, the heat-treating may be 30-200 seconds, 30-150 seconds, 30-100 seconds, 30-50 seconds. , 50-200 seconds, 100-200 seconds, or 150-200 seconds.

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

The step of heat-treating the extruded polyester foam sheet may include direct heat treatment and indirect heat treatment. For example, direct heat treatment may apply heat directly to the surface of the foam sheet. can apply heat by adjusting the temperature of the heat treatment atmosphere.

The direct heat treatment may include heating the surface temperature of the extruded polyester foam sheet to a temperature of 120-300.degree. For example, the surface temperature of the extruded polyester foam sheet may be heated to 120-300°C, 120-200°C, 120-150°C, 150-300°C, or 200-300°C.

The surface temperature of the extruded polyester foam sheet may be heated at a temperature of 120 to 300° C. by contacting one or both sides of the extruded polyester foam sheet and heat-treating the extruded polyester foam sheet. The temperature for heating one or both sides of the polyester foam sheet is 100 to 300°C, 100 to 250°C, 100 to 200°C, 100 to 150°C, 150 to 300°C, 200 to 300°C, or 250 to 300°C. can be a range.

In the indirect heat treatment, the step of heat-treating the extruded polyester foam sheet may be heat-treating in an atmosphere of 120 to 600°C. For example, the extruded polyester foam sheet is extruded and foamed by heat treatment in an atmosphere of 120 to 600°C, 120 to 400°C, 120 to 200°C, 150 to 600°C, 200 to 600°C, or 400 to 600°C. The surface temperature of the polyester foam sheet may be heated at a temperature of 120 to 300°C.

When the heat treatment temperature of the extrusion-foamed polyester foam sheet according to the present invention is within the above range, the extrusion-foamed polyester foam sheet can be easily post-foamed by 1.5 to 3 times.

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

The polyester foam sheet may have an average thickness of 1.5 to 10 mm. The average thickness of the polyester foam sheet may be 1.5 to 2 times greater than that of the extruded polyester foam sheet before heat treatment, for example, the average thickness of the polyester foam sheet is 1.5 to It can be 10 mm, 1.5-8 mm, 1.5-5 mm, 5-10 mm, or 7.5-10 mm.

The step of heat-treating the extruded and foamed polyester foam sheet increases the expansion ratio of the polyester foam sheet, so that post-foaming occurs when heat is applied to the manufactured polyester foam sheet. , the shape can be prevented from being deformed.

For example, the extruded polyester foam sheet can be heat-treated (post-foamed) by being heated while passing through a heater by a conveyor belt, and the extruded polyester foam sheet has its front end and rear end held in parallel. Heat treatment (post-foaming) can be performed by heating while passing through a heater with a nip roller.

After the heat treatment of the extruded polyester foam sheet, a step of cooling the polyester foam sheet may be further performed. In the cooling step, the polyester foam sheet may be cooled by a cooling roller while being moved by a conveyor belt. At this time, the cooling step may be performed to harden the melted portion of the polyester foam sheet due to the heat treatment, thereby preventing deformation of the polyester foam sheet.

As an example, the temperature of the cooling roller in the cooling step may be 15°C or less, 1-14.5°C, 1.5-14°C, 2-13.5°C, 2.5-13°C, 3-12°C. It can range from 5°C, from 3.5°C to 12°C, from 4°C to 11.5°C or from 4.5°C to 10°C.

After the heat treatment of the extruded polyester foam sheet, a step of cutting the polyester foam sheet at regular intervals may be further performed. In the cutting step, the polyester foam sheet may be cut by a cutter while being moved by a conveyor belt.

In the cutting step, after the extruded and foamed polyester foam sheet is heat-treated, the polyester foam sheet is moved by a conveyor belt and passed through a cooling roller to be cooled, and then cut by a cutter while being moved by a conveyor belt. . The method for producing a polyester foam sheet according to the present invention has the advantage of improving process efficiency and facilitating mass production by cutting the heat-treated, extruded and foamed polyester foam sheet with a cutter.

The polyester foam sheet according to the present invention can be applied to bulkheads inside ships, sandwich panel core materials used for building exterior materials, MDF (medium density fiberboard) substitute materials for furniture, interior and exterior materials for automobiles, and the like.

Hereinafter, the present invention will be described in more detail through examples according to the present invention, but the scope of the present invention is not limited by the examples presented below.

Example 1
In order to manufacture a polyester foam sheet, first, 100 parts by weight of polyethylene terephthalate (PET) resin was dried at 180° C. to remove moisture, and the moisture-free PET resin and the moisture-free PET resin were extruded into an extruder. Based on 100 parts by weight of PET resin, 1 part by weight of pyromellitic dianhydride (PMDA), 1 part by weight of Talc and 0.1 part by weight of Irganox (IRG 1010) were mixed and heated at 280°C. Heating was applied to produce a resin melt. Next, 1 part by weight of butane gas as a foaming agent was introduced into the extruder based on 100 parts by weight of the PET resin, and extrusion foaming was performed. The extruded polyester foam sheet was an extruded polyester foam sheet with a density of 200 kg/m ³ , a thickness of 5 mm, a crystallinity of 6% and a bending strength of 3 N/cm ² .

The extruded polyester foam sheet was heat treated (post-foaming) at a surface temperature of 180° C. while passing through a heater at a temperature of 350° C. for 60 seconds. The polyester foam sheet obtained after the heat treatment was subsequently cut by a cutting machine to produce a polyester foam sheet.

FIG. 1 schematically shows a method of manufacturing a polyester foam sheet according to Example 1, in which a polyester foam sheet 20 extruded and foamed from an extruder 10 is foamed and passed through heaters 30. , heat-treated, transferred by conveyor belt 60, and cut by cutting machine 40 to manufacture polyester foam sheet 50. FIG.

Example 2
Except that the extruded polyester foam sheet was heat-treated (post-foaming) at a surface temperature of 200 to 220 ° C. while passing through a heater at a temperature of 500 ° C. for 60 seconds. Prepared in the same manner as in Example 1.

Comparative example 1
Example 1 except that the extruded polyester foam sheet was passed through a heater at a temperature of 500° C. for 250 seconds and heat-treated at a surface temperature of 250° C. (post-foaming). manufactured in the same manner as

Comparative example 2
Example 1 except that the extruded polyester foam sheet was passed through a heater at a temperature of 350° C. for 20 seconds and heat-treated at a surface temperature of 100° C. (post-foaming). manufactured in the same manner as

Comparative example 3
The extruded polyester foam sheet obtained at room temperature (15-25° C.) without any heat treatment was subsequently cut by a cutting machine to prepare a polyester foam sheet.

Experimental example 1
The density, thickness, crystallinity, and bending strength of the polyester foam sheets produced in Examples 1 and 4 and Comparative Examples 1 to 3 were measured. The measurement method is described below, and the results are shown in Table 1 below.

(1) Density Density was measured under the conditions of KS M ISO 845.

(2) Bending strength Bending strength was measured under the conditions of KS M ISO 844.

Experimental example 2
For the polyester foam sheets produced in Examples 1 and 4 and Comparative Examples 1 to 3, the extruded polyester foam sheets were maintained in a heater at a temperature of 150° C. for 6 hours, and then extruded and foamed. The volume change rate and crystallinity of the polyester foam sheet were measured. The measurement method is described below, and the results are shown in Table 2 below.

(1) Crystallinity Crystallinity (%) = {(absolute value of heat of fusion (J/g) - absolute value of heat of crystallization (J/g)) ÷ complete heat of crystallization (J/g)} × 100

The heat of crystallization can be determined from a DSC curve measured according to KS M ISO 11357-1 "Plastics - Application of Differential Scanning Calorimeter". The measurement conditions are as described above. The crystallinity calculated in the present invention is the difference between the heat of fusion (J/g) required by the area of the heat fusion peak and the heat of crystallization (J/g) required by the area of the crystallization peak. It is the required value divided by the theoretical heat of fusion of the perfect crystal of The heat of fusion and the heat of crystallization can be calculated using analysis software attached to the apparatus.

According to Table 1, physical properties of an extruded polyester foam sheet having a density of 200 kg/m ³ , a thickness of 5 mm, a flexural strength of 3 N/cm ² and a flexural modulus of 200 MPa differ depending on the surface temperature and heat treatment time. We were able to confirm that The polyester foam sheets prepared according to Examples 1 and 2 were heat-treated at surface temperatures of 180° C. and 220° C. for 60 seconds, respectively, to increase the thickness of the polyester foam sheets by 1.5 and 2 times, respectively. On the other hand, the polyester foam sheets produced in Comparative Examples 1 and 2 were heat-treated at surface temperatures of 250° C. and 100° C. for 250 seconds (long time) and 20 seconds (short time), respectively, to reduce the thickness of the polyester foam sheet. There was almost no increase in weight. As a result, it was confirmed that the thickness of the polyester foam sheet is affected by the sheet surface temperature and the heat treatment time during the heat treatment of the extruded polyester foam sheet. The polyester foam sheets according to the examples of the present invention increased the crystallinity of the polyester foam sheets by increasing the thickness by 1.5 to 2 times. It can be said that the increase in thickness and the increase in the crystallinity of the product surface due to the heat treatment affect the improvement in the bending strength of the product.

Also, referring to Table 2, the polyester foam sheets produced according to the present invention had volume changes of 3% and 2% even after being maintained at 150° C. for 6 hours, and the volume changes were 3% and 2%, respectively. It can be seen that the thickness change is small even with additional heat treatment due to post-foaming, and the crystallinity at this time is 23-30%, which is an increase of about 5 times. In the case of Comparative Example 1, the volume change rate was similar to that of Example 2, but the crystallinity was 35%, which was much higher than that of Example 2. A high degree of crystallinity as in Comparative Example 2 may result in poor moldability, making it impossible to mold into the desired shape.

According to the above results, the polyester foam sheet according to the present invention is heat-treated and then foamed. As the post-foaming increases the thickness of the polyester foam sheet by 1.5 to 2 times, the degree of crystallinity increases and the bending strength increases.

The polyester foam sheet according to the present invention is subjected to a post-foaming process by heat-treating the polyester foam sheet, so that the volume change rate is low when heat is applied during the work using the polyester foam sheet, resulting in post-foaming phenomenon. As the thickness of the polyester foam sheet increases by 1.5 to 2 times due to post-foaming, the degree of crystallinity increases and the bending strength increases.

The polyester foam sheet according to the present invention can be applied to bulkheads inside ships, sandwich panel core materials used for building exterior materials, MDF (medium density fiberboard) substitute materials for furniture, interior and exterior materials for automobiles, and the like.

Claims (7)

heat-treating the surface temperature of the extruded polyester foam sheet at 160 to 230° C. while passing the extruded polyester foam sheet through a heater at 350 to 600° C. for 50 to 200 seconds;
The flexing strength according to KS M ISO 844 of the polyester foam sheet after the heat treatment is 5 to 30 N/cm ² ,
The average thickness of the polyester foam sheet after the heat treatment is 7.5 mm or more,
The polyester foam sheet is a polyethylene terephthalate foam sheet,
A method for producing a polyester foam sheet. The production method according to claim 1, wherein the heat-treated polyester foam sheet has a volume change rate of 5% or less after being maintained at 150°C for 6 hours. The manufacturing method according to claim 1, wherein the density according to KS M ISO 845 of the polyester foam sheet after the heat treatment is 50-350 kg/m ³ . The manufacturing method according to claim 1, wherein the polyester foam sheet after the heat treatment has an average thickness of 7.5 to 10 mm. The production method according to claim 1, wherein the polyester foam sheet after the heat treatment has a degree of crystallinity of 15 to 30%. The manufacturing method according to claim 1 , wherein the surface temperature of the extruded polyester foam sheet is 180-220°C in the heat treatment step. The production method according to claim 1, wherein the expansion ratio of the extruded polyester foam sheet after heat treatment is 1.5 to 3 times the expansion ratio before heat treatment.

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