KR101716193B1 - Core-Shell Structured Foam Comprising Hollowness - Google Patents

Abstract

The present invention relates to a composite foaming body having a core-shell structure. The composite foaming body is in a core-shell structure including a core in a hollow structure, thereby improving physical properties such as flame retardancy, elasticity and density at the same time.

Description

[0001] The present invention relates to a core-shell structured foam compres- sion hollow-

The present invention relates to a foam having a core-shell structure.

BACKGROUND ART [0002] In recent years, eco-friendly foamed molded articles have been actively developed and representative examples of the material include polyester foamed articles. The polyester is excellent in mechanical properties, and has excellent heat resistance and chemical resistance. However, it has difficulty in molding by extrusion foaming by melting as a crystalline resin. On the other hand, with the development of the technology, polyester can also be produced by the foaming process during melt extrusion. For example, U.S. Patent No. 5,099,991 discloses a method of producing an expanded molded article by extrusion foaming by adding a cross-linking agent to a polyester.

However, since the polyester foam has a low melt viscosity, it has a limitation in heightening the expansion ratio and it is difficult to increase the functionality by adding an additive.

Accordingly, there is a demand for development of an expanded molded article having various structures including the above-mentioned polyester and improved physical properties such as flame retardance, elasticity and strength.

United States Patent Number 5000991.

It is an object of the present invention to provide a foamed core-shell composite structure having improved flame retardance, elasticity and density.

According to an aspect of the present invention,

A core forming a hollow; And

A shell comprising a foam,

Wherein the core and the shell have a repeated cross-sectional structure,

Wherein the foam satisfies at least one of the following general formulas (1) to (3).

[Formula 1]

E _f ≤ 8

[Formula 2]

H _f 0.03

 [Formula 3]

D _f ≤ 60

In the general formulas 1 to 3,

E _f means the maximum heat release rate (MJ / m) for 5 minutes after the start of heating of the composite foam according to KS F ISO 5660-1,

H _f means the thermal conductivity (W / mK) of the composite foam according to KS L 9016,

D _f represents the density (kg / m ³ ) of the composite foam according to KS M ISO 845.

The composite foam according to the present invention can simultaneously improve physical properties such as flame retardance, elasticity and density by providing the core-shell structure with the first foam and the second foam having improved functions.

1 shows a structure of an extruder including a double annular nozzle according to the present invention.
2 shows a structure of a double annular nozzle according to the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by terms. Terms are used only for the purpose of distinguishing one component from another.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the present invention, the terms "comprising" or "having ", and the like, specify that the presence of a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Therefore, the configurations shown in the embodiments described herein are merely the most preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention. Therefore, various equivalents And variations.

Hereinafter, the composite foam according to the present invention will be described in detail.

As one example, the composite foams according to the present invention may comprise,

A core forming a hollow; And

A shell comprising a foam,

Wherein the core and the shell have a repeated cross-sectional structure,

The foam may satisfy at least one of the conditions of the following general formulas (1) to (3).

[Formula 1]

E _f ≤ 8

[Formula 2]

H _f 0.03

 [Formula 3]

D _f ≤ 60

In the general formulas 1 to 3,

E _f means the maximum heat release rate (MJ / m) for 5 minutes after the start of heating of the composite foam according to KS F ISO 5660-1,

H _f means the thermal conductivity (W / mK) of the composite foam according to KS L 9016,

D _f represents the density (kg / m ³ ) of the composite foam according to KS M ISO 845.

A core forming the hollow; And the shell including the foam may have a repeated cross-sectional structure of the core and the shell. The core may have a cross-sectional shape such as a circle or an ellipse. In addition, the shell may have a cross-sectional shape such as a circle, a rectangle, a pentagon, a hexagon, or a polygon. At this time, 2 to 100 core shell unit structures may be formed.

According to the general formula 1, the composite foam according to the present invention may have a maximum heat release rate of 5 MJ / m or less for 5 minutes according to KS F ISO 5660-1. Specifically, the heat release rate may be 0.01 to 7.5 MJ / m ² , 0.05 to 7 MJ / m ² , 0.1 to 5 MJ / m ^2, or 0.15 to 3 MJ / m ² . Also, the composite foam according to the present invention may have a flame retardancy of more than grade 2 based on KS F 4724. If the flame-retardant grade of the composite foam is of the above grade, it may exhibit semi-fireproof performance. Accordingly, the composite foam according to the present invention can maintain a stable shape even at a high temperature by having a maximum heat release rate and a flame retardancy grade within the above range.

According to the general formula 2, the composite foam according to the present invention may have a thermal conductivity of 0.03 W / mK or less in accordance with KS L 9016. Specifically, the thermal conductivity may be 0.01 to 0.03 W / mK, 0.015 to 0.029 W / mK, or 0.02 to 0.028 W / mK. The composite foam according to the present invention may have improved thermal insulation by having a thermal conductivity in the above range.

According to the above general formula 3, the composite foam according to the present invention may have a density of 60 kg / m ³ or less according to KS M ISO 845. Specifically, the density may range from 10 to 55 kg / m ³ , from 15 to 52 kg / m ³ , from 20 to 50 kg / m ^3, or from 30 to 45 kg / m ³ . When the density of the composite foam according to the present invention is in the above range, improved elasticity can be realized.

As an example, the absorption capacity of the composite foam according to the present invention is 1 g / 100 cm < ² > based on KS M IOS 7214 0.7 g / 100 cm < ² > 0.6 g / 100 cm < ² > 0.01 to 0.5 g / 100 cm ² or 0.1 to 0.4 g / 100 cm ² Lt; / RTI > When the absorption amount of the composite foam is in the above range, there is an advantage that it can be easily stored outside.

As one example, the foam according to the present invention may be made of polyethylene terephthalate (PET), low density or high density polyethylene (PE), vinyl chloride resin (PVC), polymethyl methacrylate (PMMA), polystyrene (PS) (PP), ethylene vinyl acetate (EVA), polyurethane (PU) and polycaprolactone.

Specifically, the foam according to the present invention may be at least one foam of a polyester resin, a polystyrene resin and a polyethylene resin.

The polyester resin mainly used so far is a high molecular weight aromatic polyester resin produced by the condensation polymerization reaction of 1,4-butanediol with terephthalic acid. Here, the high molecular weight polyester may mean a polymer having an intrinsic viscosity [?] Of 0.8 (dL / g) or more. However, the aromatic polyester resin is excellent in physical properties such as high molecular weight, thermal stability and tensile strength, but it is not decomposed in a natural ecosystem after disposal, causing serious environmental pollution problem for a long time. On the other hand, it is already known that aliphatic polyester has biodegradability. However, conventional aliphatic polyesters have a low melting point due to the flexible structure of the main chain and low crystallinity, are low in thermal stability upon melting, are likely to be thermally decomposed, have a high melt flow index, There is a problem that the use thereof is limited due to poor physical properties such as tear strength. The aliphatic polyester may include, for example, polyglycolide, polycaprolactone, polylactide, and polybutylene succinate.

Generally, polystyrene is a non-crystalline polymer obtained by radical polymerization of styrene, and is a colorless transparent thermoplastic resin. The boiling point is about 145 ° C, which is also called a styrol resin. It is made of polystyrene which is a polymer of liquid styrene unit produced by the reaction of ethylene and benzene. It is not easily eroded by chemicals, easy to process, and has a high refractive index. In addition, it becomes a hard molded product (molded product) and has excellent characteristics as an electric insulating material.

Generally, various kinds of polyethylene are produced according to a polymerization method. For example, low-density polyethylene and high-density polyethylene are classified according to density. At present, the main products are low density polyethylene (soft polyethylene) and C type high density polyethylene (hard polyethylene) corresponding to A, and a lot of low density polyethylene is being produced. Low-density polyethylene is produced by heating at a high temperature of 200 atm or higher at 1,000 atm with a trace amount of air as a catalyst, and is therefore also referred to as high-pressure polyethylene. The low-density polyethylene has a density of about 0.91, and because of its branches, the molecular arrangement is insufficient and the crystallized portion is about 65% so that the low-density polyethylene elongates well and has a small tensile strength but a high impact resistance. Therefore, there are characteristics that are easy to process and easy to use. The high-density polyethylene is polymerized with ethylene at a temperature of about 70 ° C and 10 atm using a so-called chi-glazing catalyst (a complex catalyst consisting of titanium tetrachloride and triethylaluminum). It is generally called low-pressure polyethylene. It has a softening point, a high hardness and a high strength, but has a small elongation and impact resistance and a hard feel. It has few branches and a high crystallinity, reaching 85% and a density of over 0.95.

More specifically, in the present invention, the foam may be a polyester resin. The polyester resin is not limited as long as it can maintain the physical properties of the polyester and is excellent in softness characteristics and foam forming workability. As one example, the polyester resin may have biodegradability.

Specific examples of the polyester include polyethylene terephthalate (PET), polystyrene (PS), polybutylene terephthalate (PBT), polylactic acid (PLA), poly Polyglycolic acid (PGA), polypropylene (PP), polyethylene (PE), polyethylene adipate (PEA), polyhydroxyalkanoate (PHA), polytrimethylene terephthalate And may be at least one selected from the group consisting of Polytrimethylene Terephthalate (PTT) and Polyethylene naphthalate (PEN). Specifically, polyethylene terephthalate (PET) may be used in the present invention.

As an example, the composite foam according to the present invention may be a closed cell (DIN ISO4590) where at least 90% of the cells are closed cells. This may mean that the measured value of the composite foam according to DIN ISO 4590 is that at least 90% of the cells are closed cells. For example, the closed cell of the composite foam may be 90-100% or 95-100%. The composite foam according to the present invention has closed cells within the above range, so that excellent heat insulating properties can be realized. Thus, the composite foam can be widely used in the construction industry for insulation of a part of a building, for example, a foundation, a wall, a floor and a roof. For example, the number of cells of the complex multiplier may comprise 1 to 30 cells, 3 to 25 cells, or 3 to 20 cells per mm.

As one example, the composite foam may be an extrusion foam molding.

Specifically, there are types of foaming methods largely bead foaming or extrusion foaming. In general, the bead foaming is a method of heating a resin bead to form a primary foam, aging the resin bead for a suitable time, filling the resin bead in a plate-shaped or cylindrical mold, heating the same again, and fusing and forming the product by secondary foaming.

On the other hand, the extrusion foaming can simplify the process steps by heating and melting the resin and continuously extruding and foaming the resin melt, and it is possible to mass-produce, and the cracks, Development and the like can be prevented, and more excellent bending strength and compressive strength can be realized.

As one example, the composite foam according to the present invention may have a hydrophilization function, a waterproof function, a flame retarding function or a UV blocking function and may be used as a surfactant, a UV blocking agent, a hydrophilic agent, a flame retardant, a heat stabilizer, The composition may further comprise at least one functional additive selected from the group consisting of an antioxidant, an infrared attenuating agent, a plasticizer, a fire retardant chemical, a pigment, an elastic polymer, an extrusion aid, an antioxidant, a filler, an antistatic agent and a UV absorber. Specifically, the composite foam of the present invention may comprise a chain extending additive, a filler, a heat stabilizer, and a blowing agent.

Although the chain extending additive is not particularly limited, for example, pyromellitic dianhydride (PMDA) may be used in the present invention.

Examples of the filler 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, Inorganic compounds such as sodium hydrogencarbonate and glass beads, organic compounds such as polytetrafluoroethylene and azodicarbonamide, mixtures of sodium hydrogencarbonate and citric acid, and inert gases such as nitrogen. These fillers can serve to impart functionalities and reduce the cost of the composite foam. Specifically, Talc may be used in the present invention.

The heat stabilizer may be an organic or inorganic compound. The organic or inorganic phosphorus compound may be, for example, phosphoric acid and organic esters thereof, phosphorous acid and organic esters thereof. For example, the heat stabilizer may be a commercially available material, such as phosphoric acid, alkyl phosphate or aryl phosphate. Specifically, in the present invention, the heat stabilizer may be triphenyl phosphate, but it is not limited thereto. The thermostabilizer may be used within a conventional range without limitation as long as it can improve the thermal stability of the composite foam.

Examples of the blowing agent include a physical blowing agent such as N ₂ , CO ₂ and Freon and a physical blowing agent such as butane, pentane, neopentane, hexane, isohexane, heptane, isoheptane, methyl chloride, etc. or azodicarbonamide , P, P'-oxybis (benzene sulfonyl hydrazide) [P, P'-oxy bis (benzene sulfonyl hydrazide)] compounds, N, N'- dinitrosopentamethylenetetramine -dinitroso pentamethylene tetramine) compound. Specifically, CO ₂ can be used in the present invention.

The flame retardant in the present invention is not particularly limited and may include, for example, a bromine compound, phosphorus or phosphorus compound, antimony compound, metal hydroxide and the like. The bromine compound includes, for example, tetrabromobisphenol A and decabromodiphenyl ether, and the phosphorus or phosphorus compound includes an aromatic phosphoric acid ester, an aromatic condensed phosphoric acid ester, a halogenated phosphoric acid ester, and the like, and the antimony compound Antimony trioxide, antimony pentoxide, and the like. Examples of the metal element in the metal hydroxide include aluminum (Al), magnesium (Mg), calcium (Ca), nickel (Ni), cobalt (Co), tin (Sn), zinc (Zn) ), Iron (Fe), titanium (Ti), boron (B), and the like. Of these, aluminum and magnesium are preferable. The metal hydroxide may be composed of one kind of metal element or two or more kinds of metal elements. For example, metal hydroxides composed of one kind of metal element may include aluminum hydroxide, magnesium hydroxide, and the like.

The surfactant is not particularly limited, and examples thereof include anionic surfactants (e.g., fatty acid salts, alkylsulfuric acid ester salts, alkylbenzenesulfonic acid salts, alkylnaphthalenesulfonic acid salts, alkylsulfosuccinic acid salts and polyoxyethylene alkylsulfuric acid ester salts) , Nonionic surfactants (for example, polyoxyalkylene alkyl ethers such as polyoxyethylene alkyl ethers, polyoxyethylene derivatives, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, (E.g., alkylamine salts, quaternary ammonium salts, alkylbetaines, amine oxides, etc.), and water-soluble polymers such as polyoxyethylene alkylamines and alkylalkanolamides), cationic and amphoteric surfactants Or protective colloids (e.g., gelatin, methylcellulose, hydroxyethylcellulose, Polyoxyethylene-polyoxypropylene block copolymer, polyacrylamide, polyacrylic acid, polyacrylic acid salt, sodium alginate, polyvinyl alcohol partial saponification, etc.), and the like have.

The waterproofing agent is not particularly limited and includes, for example, silicone, epoxy, cyanoacrylate, polyvinyl acrylate, ethylene vinyl acetate, acrylate, polychloroprene, polyurethane and polyester resins , A mixture of polyol and polyurethane resin, a mixture of acrylic polymer and polyurethane resin, a polyimide, and a mixture of cyanoacrylate and urethane.

The ultraviolet screening agent is not particularly limited and may be, for example, an organic or inorganic ultraviolet screening agent. Examples of the organic ultraviolet screening agent include p-aminobenzoic acid derivatives, benzylidene camphor derivatives, cinnamic acid derivatives, Benzotriazole derivatives, and mixtures thereof. Examples of the inorganic ultraviolet screening agent may include titanium dioxide, zinc oxide, manganese oxide, zirconium dioxide, cerium dioxide, and mixtures thereof.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. However, the scope of the present invention is not limited by the following description.

Example

In order to produce the composite foam according to the present invention, the PET resin for forming the shell was first dried at 130 DEG C to remove water. Then, 100 phr of PET resin, 1 phr of PMDA, 1 phr of talc, and 0.1 phr of Irganox (IRG 1010) were added to a first extruder having a double annular structure and the resin melt was prepared by heating at 280 ° C Respectively. Subsequently, carbonic acid gas was added as a blowing agent to the resin melt, mixed thoroughly, and then sent to a second extruder and cooled to 220 ° C. The cooled resin melt was extruded and foamed while passing through a die, and a composite foam of a core-shell structure having a core forming a hollow by injecting carbon dioxide gas into the extruder was manufactured.

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Comparative Example

100 parts by weight of PET resin was dried at 130 DEG C to remove moisture. In the first extruder, 1 part by weight of PET resin, PMDA (pyromellitic dianhydride), 1 part by weight talc, Irganox (IRG 1010) , And the mixture was heated to 280 占 폚 to prepare a resin melt. Then, carbonic acid gas was mixed as a blowing agent in the first extruder, and the resin melt was sent to the second extruder and cooled to 220 캜. The cooled resin melt was extruded and foamed through a die to form a resin foam.

Experimental Example

The heat release rate, hardness, compressive strength and density were measured using the composite foam prepared in the above Examples and Comparative Examples. The measurement method is described below, and the results are shown in Table 1 below.

1) Measurement of heat release rate

The maximum heat release rate (MJ / m) for 5 minutes after initiation of heating under the conditions of KS F ISO 5660-1 was measured.

2) Measurement of thermal conductivity (measurement of heat insulation)

The thermal conductivity was measured under KS L 9016 conditions.

3) Compressive strength measurement

The compressive strength was measured under KS M ISO 844 conditions.

4) Density measurement

The density was measured under KS M ISO 845 conditions.

Example Comparative Example Heat release rate (MJ / m) 5 7 Thermal conductivity (W / mK) 0.028 0.034 Compressive strength (N / cm ² ) 60 80 Density (kg / m ³ ) 40 60

In Table 1, the low thermal conductivity value of 0.028 and the maximum heat release rate for 5 minutes after heating were measured to be 5 MJ / m, thus confirming that both the heat insulating performance and the flame retardant performance are satisfied at the same time. On the other hand, the comparative example satisfies the flame retardant performance, but it is confirmed that the heat insulating performance is somewhat deteriorated due to the high thermal conductivity

100: double annular nozzle
10: medial
20: outside

Claims (3)

A core which forms a hollow and contains carbon dioxide in the hollow; And
A foam shell comprising a polyethylene terephthalate resin,
Wherein the core shell unit structure having a structure in which the foam shell surrounds the periphery of the core forming the hollow has a repeated cross-sectional structure.
The method according to claim 1,
The composite foam is a composite foam characterized by satisfying the following general formulas (1) to (3):
[Formula 1]
0.1? E _f ? 5
[Formula 2]
0.015? H _f ? 0.03
[Formula 3]
10? D _f ? 55
In the general formulas 1 to 3,
E _f means the maximum heat release rate (MJ / m ² ) for 5 minutes after the start of heating of the composite foam according to KS F ISO 5660-1,
H _f means the thermal conductivity (W / mK) of the composite foam according to KS L 9016
D _f means the density (kg / m ³ ) of the composite foam according to KS M ISO 845. delete

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