KR20200072357A - Foam having low melting point resin and a molded product including the same - Google Patents

Abstract

The present invention relates to foam comprising a low-melting-point resin. The foam according to the present invention comprises a core part and a sheath part encompassing the core part, and, particularly, the sheath part comprises a low-melting-point polyester resin, and thus can implement excellent processability without the degradation of physical properties such as strength and durability.

Description

Foam having a low melting point resin and a molded body containing the same {Foam having low melting point resin and a molded product including the same}

The present invention relates to a foam comprising a low melting point resin and a molded article comprising the same.

Plastic foamed molded articles have been widely used throughout the industry due to their advantageous properties such as light weight, cushioning, heat insulation, moldability, and energy saving. Polymers such as polystyrene, polyolefin, or polyvinyl chloride are amorphous and have a high melt viscosity, and at the same time, have a low viscosity change due to temperature change, and have easy foaming properties. They are used in a variety of ways, such as insulation, structural materials, cushioning materials, and packaging containers. have. However, the polymers described above are vulnerable to fire, and have the disadvantages of releasing environmental hormones and low physical properties.

Recently, development of eco-friendly foamed moldings has been actively conducted, and polyester foams are representative materials. Polyester has excellent mechanical properties, excellent heat resistance, chemical resistance, and the like, but it is difficult to form by melting and extruding as a crystalline resin. On the other hand, with the development of technology, it is possible to manufacture a foamed molded body through a foaming process during melt extrusion. For example, US Patent No. 5000991 discloses a technique for producing a foamed molded article by extrusion foaming by adding a crosslinking agent to polyester.

However, the polyester foam has a limitation in increasing the foaming magnification and thus has a limited use purpose. Accordingly, there is a need to develop a foam having an improved foam magnification while maintaining the advantages of excellent physical performance of the polyester.

U.S. Patent No. 5000991

The present invention is to solve the above-mentioned problems, the object of the present invention is to provide a foam having excellent processability, excellent physical performance, and a molded article comprising the same.

The present invention,

A core portion comprising a polyester resin foam; And

It provides a foam having a cross-sectional shape in which the structure surrounding the core portion and the structure including a sheath portion comprising a polyester resin having a melting point of 150 to 250°C or a softening point of 100 to 150°C are repeated.

In addition, the present invention provides a molded body comprising the foam.

The foam according to the present invention includes a core portion and a sheath portion surrounding the core portion, and in particular, since the sheath portion is made of a low melting point polyester resin, it has an advantage of realizing excellent workability without physical resistance such as strength and durability.

1 is a view showing a cross-section of a unit structure according to the present invention.
2 is a view showing a cross-section of a molded body according to the present invention.

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

However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

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

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

In the present invention, "unit structure" refers to a foam for foaming beads, and more specifically, a unit including a core portion including a polyester resin foam and a sheath portion comprising a polyester resin having a structure surrounding the core portion. Structure.

Meanwhile, the "molded body" has a structure in which the foam is repeated, and may have a cross-sectional structure in which the unit structure is repeated. However, the polyester resin forming the sheath portion may be partially fused to each other.

In addition, "melting point" means the temperature at which a solid resin starts to melt in a liquid phase. In particular, the expression "low melting point resin" can be interpreted in a relative sense, in the present invention means a resin having a low melting point (or softening point) of about 150 to 250°C or a softening point of about 100 to 150°C. can do.

In addition, in the present invention, "polymer" means an oligomer and/or polymer obtained by performing a polymerization reaction of a monomer or a compound containing a polymerizable reactive group.

Furthermore, in the present invention, "cell" means a microstructure expanded by foaming in a polymer.

In addition, in the present invention, "parts by weight" means a weight ratio between each component, and "molar parts" means a mole fraction between each component.

1 is a view showing a cross-section of a unit structure according to the invention, Figure 2 is a view showing a cross-section of the foam according to the invention. Hereinafter, the foam according to the present invention will be described in detail with reference to FIGS. 1 and 2.

The present invention relates to a foam comprising a low melting point resin. The foam according to the present invention includes a unit structure 100 consisting of a core portion 110 and a sheath portion 120 surrounding the core portion 110, in particular, the sheath portion 120 is a low-melting polyester resin Since it is made of, there is an advantage that can realize excellent workability without physical properties such as strength and durability.

The present invention provides a foam comprising a low melting point resin.

In one embodiment, the foam according to the present invention includes a structure in which the unit structure 100 including the core part 110 and the sheath part 120 is repeated.

Specifically, the unit structure 100 is a core-sheath structure, the core part 110 includes a polyester resin foam 100, and the sheath part 120 is a structure surrounding the core part 110. Furnace is a structure formed of a polyester resin having a melting point of 150 to 250°C or a softening point of 100 to 150°C.

In particular, the foam has the advantage of being able to realize excellent processability without physical resistance, such as strength and durability, during molding of the molded body, including the core portion 110 of the high melting point and the sheath portion 110 of the low melting point.

In the present invention, the expressions'low melting point' to'high melting point' may be interpreted in a relative sense. In the present invention, the core portion 110 may be formed of a polyester resin foam having a high melting point, and the sheath portion 120 may be made of polyester resin having a melting point of 150 to 250°C or a softening point of 100 to 150°C. Is formed. The polyester resin constituting the sheath portion 120 may also be referred to as a low melting point polyester resin in a relative sense.

First, the core portion 110 of the unit structure 100 may include a polyester resin foam, and the polyester resin foam can maintain the physical properties of the polyester while having biodegradability, soft characteristics and foam molding processability If it is excellent, it is not limited greatly.

The polyester resin mainly used so far is a high molecular weight aromatic polyester resin produced by condensation polymerization reaction with terephthalic acid and 1,4-butanediol. Here, the high molecular weight polyester may mean a polymer having an intrinsic viscosity [η] of 0.8 (dL/g) or higher. However, the aromatic polyester resin is excellent in physical properties such as high molecular weight, thermal stability, and tensile strength, but does not decompose in the natural ecosystem after disposal and remains for a long time, causing serious environmental pollution problems.

On the other hand, it is already known that aliphatic polyesters have biodegradability. However, the existing aliphatic polyester has a low melting point due to the flexible structure and low crystallinity of the main chain, and it is easy to decompose thermally due to low thermal stability, and has a high melt flow index. There was a problem that the use is limited due to poor physical properties such as thermal strength. The aliphatic polyester may include, for example, polyglycolide, polycaprolactone, polylactide, polybutylene succinate, and the like.

Specifically, the type of the polyester, for example, polyethylene terephthalate (PET), polystyrene (PS), polybutylene terephthalate (Polybutylene Terephthalate, PBT), polylactic acid (Poly Lactic acid, PLA), poly Polyglycolic acid (PGA), Polypropylene (PP), Polyethylene (PE), Polyethylene adipate (PEA), Polyhydroalkanoate (PHA), Polytrimethylene tere It may be one or more selected from the group consisting of phthalate (Polytrimethylene terephthalate, PTT) and polyethylene naphthalate (PEN). Specifically, in the present invention, polyethylene terephthalate (PET) may be used.

Meanwhile, the polyester resin foam of the core portion 110 may be a high melting point polyester resin foam, and may have a melting point of 240° C. or higher. Specifically, it may be in the range of 241 to 255°C or 255°C.

That is, the unit structure 100 of the present invention may be made of a core resin of a high melting point polyester resin foam and a low melting polyester resin surrounding the core portion 110. In particular, the foam according to the present invention is formed by melting the low melting point polyester resin constituting the sheath portion 120 after molding, and thus forming a partially fused form of the resin between each other. The shape can be maintained, and the shape of the foam cell can be maintained by a high melting point resin.

Hereinafter, the polyester resin forming the sheath portion 120 according to the present invention will be described in more detail.

The sheath portion 120 includes a case of a polyester resin including repeating units represented by the following Chemical Formula 1 and Chemical Formula 2.

[Formula 1]

;

;

[Formula 2]

;

;

In Formula 1 and Formula 2,

m and n represent the molar fraction of repeating units contained in the polyester resin,

n is 0.05 to 0.5 based on m+n=1.

The polyester resin of the sheath portion 120 is characterized by being a low melting point polyester resin. The low melting point polyester resin may have a structure including repeating units represented by Chemical Formulas 1 and 2. The repeating unit represented by Chemical Formula 1 represents a repeating unit of polyethylene terephthalate (PET), and the repeating unit represented by Chemical Formula 2 improves tearing properties of a polyester resin comprising a repeating unit of polyethylene terephthalate (PET). Perform a function. Specifically, the repeating unit represented by Chemical Formula 2 includes a methyl group (-CH ₃ ) as a side chain in the propylene chain bonded to terephthalate to increase the degree of freedom of the main chain by securing a space for the main chain of the polymerized resin to rotate and The melting point (Tm) may be lowered by inducing a decrease in crystallinity of the resin. This may exhibit the same effect as when using isophthalic acid (IPA) containing an asymmetric aromatic ring to lower the melting point (Tm) of a conventional crystalline polyester resin.

At this time, the low melting point polyester resin may include a repeating unit of Formula 2 that lowers the melting point (Tm) of the resin as a main repeating unit together with a repeating unit of Formula 1 including an ester repeating unit. Specifically, the low-melting polyester resin of the present invention, when the molar fraction of the total resin is 1, may include repeating units represented by Chemical Formulas 1 and 2 in 0.5 to 1, specifically 0.55 to 1, 0.6 to 1, 0.7 to 1, 0.8 to 1, 0.5 to 0.9, 0.5 to 0.85, 0.5 to 0.7, or 0.6 to 0.95.

In addition, the amount of the repeating unit represented by Formula 2 contained in the low-melting polyester resin may be 0.05 to 0.5 when the total fraction including the repeating unit represented by Formula 1 is 1 (m+n=1), specifically May be 0.05 to 0.4, 0.1 to 0.4, 0.15 to 0.35, or 0.2 to 0.3.

In addition, the melting point (Tm) of the low melting point polyester resin may be 150°C to 250°C, or a melting point may not exist. Specifically, the melting point (Tm) may be 150 ℃ to 250 ℃, 160 ℃ to 240 ℃, 170 ℃ to 230 ℃, 180 ℃ to 220 ℃, 190 ℃ to 210 ℃, or 195 ℃ to 200 ℃ or not present .

In addition, the softening point of the low-melting polyester resin may be 100 ℃ to 150 ℃, specifically 100 ℃ to 130 ℃, 118 ℃ to 128 ℃, 120 ℃ to 125 ℃, 121 ℃ to 124 ℃, 124 ℃ To 128°C, or 119°C to 126°C.

Furthermore, the low melting point polyester resin may have a glass transition temperature (Tg) of 50°C or higher. Specifically, the glass transition temperature may be 50 ℃ to 80 ℃, more specifically 61 ℃ to 69 ℃, 60 ℃ to 65 ℃, 63 ℃ to 67 ℃, 61 ℃ to 63 ℃, 63 ℃ to 65 ℃, 65 ℃ to 67 ℃, or 62 ℃ to 67 ℃.

In addition, the low-melting polyester resin may have an intrinsic viscosity (I.V) of 0.5 ㎗/g to 0.75 ㎗/g. Specifically, the intrinsic viscosity (IV) is 0.6 ㎗/g to 0.65 ㎗/g, 0.65 ㎗/g to 0.70 ㎗/g, 0.64 ㎗/g to 0.69 ㎗/g, 0.65 ㎗/g to 0.68 ㎗/g, 0.67 ㎗/g to 0.75 ㎗/g, 0.69 ㎗/g to 0.72 ㎗/g, 0.7 ㎗/g to 0.75 ㎗/g, or 0.63 ㎗/g to 0.67 ㎗/g.

The low-melting-point polyester resin according to the present invention may include a repeating unit represented by Chemical Formula 2 to adjust the melting point (Tm), softening point, and glass transition temperature (Tg) to the above range, and the resin whose physical properties are adjusted to the above range is It can exhibit excellent adhesion.

On the other hand, the low-melting polyester resin forming the sheath portion 120 may further include a repeating unit represented by the following formula (3) together with the repeating units represented by the formulas (1) and (2).

[Formula 3]

;

;

In Chemical Formula 3,

X is a 2-methylpropylene group, an ethylene group or an oxydiethylene group,

r is the molar fraction of repeating units contained in the low-melting polyester resin, and is 0.3 or less.

Specifically, in Formula 3, r may be 0 to 0.3, 0.25 or less, 0.2 or less, 0.15 or less, or 0.1 or less.

By using the repeating unit represented by the formula (3) together, it is possible to significantly reduce the content of a cyclic compound having a low melting point and a dispersion produced during polymerization, for example, polymerization degrees 2 to 3.

As one example, the low-melting polyester resin according to the present invention may contain 1% by weight based on the total resin weight by reducing the content of the cyclic compounds of polymerization degree 2 to 3, specifically, the total resin weight Based on 0.5 wt% or less, 0.4 wt% or less, 0.3 wt% or less, or 0.2 wt% or less, or may not include the cyclic compound.

In addition, the foam according to the present invention may have an average basis weight in the range of 300 to 3,000 g/m ² . Specifically, the basis weight is 350 to 2,500 g/m ² , 380 to 2,000 g/m ² , 400 to 1,500 g/m ² , 430 to 1,000 g/m ² , 450 to 950 g/m ² , 480 to 900 g/ m ² , 500 to 850 g/m ² , 530 to 800 g/m ² or 550 to 750 g/m ² .

By satisfying the above range, the basis weight of the composite according to the present invention satisfies the above-described light weight, and at the same time, it is possible to realize an improved flexural strength and flexural modulus, thereby facilitating transport and construction when working with building materials or automobile materials. have.

The density of the foam according to the invention may be 20 to 500 kg/m ³ . Specifically, the density of the foam sheet is 20 to 500 kg/m ³ , 50 to 450 kg/m ³ , 80 to 400 kg/m ³ , 110 to 350 kg/m ³ , 130 to 300 kg/m ³ , 160 to 250 kg/m ³ , or 190 to 200 kg/m ³ . The density of the foam according to the present invention has the above range, it is possible to implement an improved compressive strength while satisfying a thin thickness.

As an example, in the polyester foam included in the core portion 110 according to the present invention, 90% or more of the cells may be closed cells (DIN ISO4590).

Meanwhile, the average cell size of the foam may have 110 to 450 μm, 130 to 430 μm, 150 to 410 μm, 180 to 400 μm, 200 to 380 μm, 220 to 360 μm, or 250 to 350 μm. When the average cell size of the foam sheet is within the above range, the moldability of the molded body is improved.

As an example, the foam according to the present invention may be a bead foam molded body. Specifically, there are largely two types of foaming methods: extrusion foaming and bead foaming. The extrusion foaming is a foaming method capable of simplifying the process by heating and melting the resin and continuously extruding and foaming the resin melt, and mass production.

On the other hand, bead foaming is a method of forming a product by heating the beads for primary foaming, aging them for an appropriate time, filling the molds in a plate shape or a cylindrical shape, and heating them again to fuse and mold them by secondary foaming. More specifically, the foam according to the present invention can be molded into a product having a complex 3D structure by bead foam molding, and by reducing the temperature and time during molding, it is possible to reduce the process cost, and the resin of the core and sheath parts can be formed. It has excellent compatibility and excellent shape retention.

As an example, the foam according to the present invention may have a hydrophilicity function, a waterproofing function, a flame retardant function or a UV blocking function, and a surfactant, a sunscreen, a hydrophilizing agent, a flame retardant, a heat stabilizer, a waterproofing agent, and a cell size expansion agent , Infrared attenuators, plasticizers, fire retardant chemicals, pigments, elastomers, extrusion aids, antioxidants, fillers, anti-static agents, and UV absorbers. Specifically, the foam of the present invention may include a chain extension additive, a filler, a heat stabilizer and a foaming agent.

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

Examples of the filler, talc, mica, silica, diatomaceous earth, alumina, titanium oxide, zinc oxide, magnesium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, potassium carbonate, calcium carbonate, magnesium carbonate, calcium sulfate, barium sulfate, Inorganic compounds such as sodium hydrogen carbonate and glass beads; Organic compounds such as polytetrafluoroethylene and azodicarbonamide; A mixture of sodium hydrogen carbonate and citric acid; And an inert gas such as nitrogen. These fillers may serve to impart the functionality of the resin foam, reduce the cost, and the like. Specifically, talc may be used in the present invention.

The heat stabilizer may be an organic or inorganic compound. The organic or inorganic 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, alkyl phosphate or aryl phosphate. Specifically, in the present invention, the thermal stabilizer may be triphenyl phosphate, but is not limited thereto, and can be used without limitation within a typical range as long as it can improve the thermal stability of the resin foam.

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

The surfactant is not particularly limited, and anionic surfactants (for example, fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonate salts, alkyl naphthalene sulfonate salts, alkyl sulfosuccinate salts, steric salts of polyoxyethylene alkyl sulfates) Etc.), 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 acids Esters, glycerin fatty acid esters, polyoxyethylene alkylamines, alkylalkanolamides, etc.), cationic and amphoteric surfactants (e.g., alkylamine salts, quaternary ammonium salts, alkylbetaines, amine oxides, etc.) and Water-soluble polymers or protective colloids (e.g., gelatin, methylcellulose, hydroxyethylcellulose, hydroxypropyl cellulose, carboxymethylcellulose, polyethylene glycol, polyoxyethylene-polyoxypropylene block copolymer, polyacrylamide, polyacrylic acid , Polyacrylic acid salt, sodium alginate, polyvinyl alcohol partial saponification, etc.).

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

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

In addition, the present invention provides a molded body 10 comprising the above-mentioned foam.

The molded body 10 has a cross-sectional shape in which the structure including the core 110 and the sheath portion 120 of the foam is repeated, and the polyester resin forming the sheath portion 120 is partially fused between the polyester resins. Can be in the form of

Specifically, the molded body 10 has a cross-sectional structure in which the unit structure 100 is repeated, and the arrangement structure is not particularly limited, for example, a poly forming the sheath portion 120 of the unit structure 100 The ester resin may be in the form of partially fused to each other of the polyester resin. The partially fused form between the resins is subjected to heat and/or pressure during thermoforming or bead foaming, and forms a partially fused form between the resins in the process. The sheath part 120 according to the present invention may form a partially fused form between the polyester resins through low-temperature molding by including a low-melting point resin, which is a polyester resin having a low melting point.

Hereinafter, the present invention will be described in more detail by examples and experimental examples.

However, the following examples and experimental examples are merely illustrative of the present invention, and the contents of the present invention are not limited to the following examples and experimental examples.

< Example >

Example One.

A foam containing a core portion including a high melting point PET foam and a sheath portion containing a low melting point PET resin surrounding the core portion was bead-foamed to form a packaging container having a diameter of 10 cm and a height of 20 cm.

Specifically, the foam was first foamed, aged for 60 minutes, and then foamed in a mold to prepare a molded product.

At this time, the melting point of the high melting point PET foam was 250°C, the melting point of the low melting point PET resin was 160°C, and the molding temperature was 180°C. In addition, the volume ratio of the core portion and the sheath portion was 50:50 (%) (see Table 1).

Example 2.

The container was molded in the same manner as in Example 1, except that the volume ratio of the core portion and the sheath portion was 80:20 (%).

Comparative example One.

The container was molded in the same manner as in Example 1, except that a high melting point PET foam having a melting point of 250°C was used.

Comparative example 2.

The container was molded in the same manner as in Example 1, except that a low melting point PET foam having a melting point of 160°C was used.

Food packaging containers were prepared by changing the materials and molding conditions of Examples and Comparative Examples as shown in Table 1 below.

Referring to Table 1, the food packaging containers prepared in Examples 1 and 2 could be molded at a low molding temperature, and the molding time could be reduced while producing a product having excellent moldability.

In addition, it was possible to prevent an increase in product density generated during molding.

Comparative Example 1 could be molded at a relatively high temperature (240°C), the molding time was long, and the product density was increased after molding. On the other hand, Comparative Example 2 could be molded for a short time at a low temperature, but the density was increased and the moldability was poor due to fracture during molding.

10: molded body
100: unit structure
110: core
120: sheath

Claims (8)

A core portion comprising a polyester resin foam; And
Foam having a structure surrounding the core portion, the sheath portion comprising a polyester resin having a melting point of 150 to 250°C or a softening point of 100 to 150°C.
According to claim 1,
The polyester resin foam of the core portion has a melting point of 240°C or higher.
According to claim 1,
The polyester resin foam forming the core portion is a polyethylene terephthalate resin foam,
The polyester resin forming the sheath portion is a polyethylene terephthalate resin.
According to claim 1,
The cis part is a polyester resin comprising a repeating unit represented by the following Chemical Formula 1 and Chemical Formula 2:
[Formula 1]

;
[Formula 2]

;
In Formula 1 and Formula 2,
m and n represent the molar fraction of repeating units contained in the polyester resin,
n is 0.05 to 0.5 based on m+n=1.
According to claim 4,
The cis part is a foam characterized in that it further comprises a repeating unit represented by the following formula (3):
[Formula 3]

;
In Chemical Formula 3,
X is a 2-methylpropylene group, an ethylene group or an oxydiethylene group,
r is the mole fraction of repeating units contained in the low-melting polyester resin, and is 0.3 or less.
According to claim 1,
Foam having an average density of 20 to 500 kg/m ³ .
A molded article comprising the foam according to claim 1.
The method of claim 7,
The structure including the core and sheath portion of the foam has a repeating cross-sectional shape,
The polyester resin forming the sheath portion is a molded article characterized in that the polyester resin is partially fused to each other.

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