KR20140144088A - Expandable composite resin particle, method for preparing the same, and foamed molded article - Google Patents

Abstract

A foamed composite resin particle of the present invention is a particle in a core/shell form consisting of: a core; and a shell covering the core, wherein the core comprises an aromatic vinyl-based resin (a1), a first polyolefin-based resin (a2), and an inorganic nucleating agent (a3), the shell comprises a second polyolefin-based resin (b1) and a gas barrier property resin (b2), and a foaming agent is impregnated in the core and the shell. The foamed composite resin particle has a spherical shape in a core/shell structure, and has excellent mold internal filling property, crack resistance, compression strength, flexure strength, duration of the foaming agent, and foaming property.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an expandable composite resin particle,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a foamable composite resin particle, a production method thereof, and an expanded molded article. More specifically, the present invention relates to a foamed composite resin particle having a spherical shape of a core / shell structure and excellent in mold filling property, cracking resistance, compressive strength, flexural strength, foaming agent retainability and foamability, a production method thereof and an expanded molded article.

General polyolefin resin expanded molded articles are excellent in impact resistance, flexural strength, resilience, heat resistance, and chemical resistance and are used as automobile members such as shock absorbers and bumper cushioning materials, and packaging materials for precision electric appliances. However, even if the polyolefin-based resin is impregnated with a polyolefin-based resin particle to produce a foamed polyolefin-based resin particle, a foaming agent is easily permeated through a volatile foaming agent such as propane, butane or pentane, It is difficult to store for a long period of time, and it is necessary to foam the foamed molded article within a short time.

That is, the polyolefin-based resin expanded molded article must be foamed and molded immediately after impregnation with the foaming agent to the resin particles. It is difficult to carry over long distances and long-term storage, and the transportation and storage ratio is high. Thus, compared with polystyrene-based resin particles and polystyrene- Which is disadvantageous.

The polystyrene-based resin expanded molded article is obtained by heating foamed polystyrene type resin particles by steam or the like to a temperature above the softening point to prepare pre-expanded beads having independent bubbles therein, heating them in a mold with steam, Can be manufactured. The foamed molded article obtained from the expandable polystyrene type resin particle has high strength, light weight, cushioning property, waterproof property, thermal insulation property and heat insulation property and is used as packaging materials for household appliances, agricultural products boxes,

However, the above-mentioned polystyrene-based resin expanded molded article is superior in lightweight property due to high heat insulation property, expansion ratio and the like as compared with the polyolefin-based resin expanded molded article, but has a low impact resistance and chemical resistance.

In order to solve the problems of the above polystyrene-based and polyolefin-based resin expanded molded articles, resin particles, expanded molded articles and the like using a polystyrene-based resin together with a polyolefin-based resin excellent in flexibility and crack resistance have been developed.

Japanese Patent Application Laid-Open No. 2006-070202 discloses a resin composition containing 300 to 1,000 parts by weight of a styrene resin component and a volatile foaming agent per 100 parts by weight of a polyethylene resin component having an melting point of 95 to 115 캜 and containing an inorganic nucleating agent , And styrene-modified polyethylene expanded resin particles in which styrene-based resin particles of 0.8 m or less are dispersed in a surface layer portion of at least 5 mu m from the particle surface. The foamed resin particle contains the styrene resin component in an excessively larger amount than the polyethylene-based resin component, so that the foaming agent retainability is good and the foam molding time of the foamable resin particle is improved, but the improvement in crack resistance is insufficient.

In addition, U.S. Patent US 2004/0152795 A1 discloses an elastic particle foam comprising expandable interpolymer particles. The interpolymer can be obtained by polymerization of styrene in the presence of a polyolefin in an aqueous suspension, which can form an interpenetrating network of styrene polymers and olefin polymers. However, the foaming agent rapidly diffuses from the expandable polymer particles. Therefore, the foamable polymer particles must be stored at a low temperature, and it is difficult to maintain foamability for a long time.

Therefore, development of foamable composite resin particles and foamed molded articles which are excellent in mold filling property, cracking resistance, compressive strength, bending strength, retaining property of foaming agent, and which can maintain foaming property for a long time is required.

An object of the present invention is to provide a foamable composite resin particle having a spherical shape of a core / shell structure, excellent in crack resistance and retainability of a foaming agent, and capable of maintaining foamability for a long time, a method for producing the same, and an expanded molded article.

Another object of the present invention is to provide a foamed composite resin particle having excellent mold filling property, compressive strength and flexural strength, a process for producing the same, and an expanded molded article.

These and other objects of the present invention can be achieved by the present invention which is described in detail.

One aspect of the present invention relates to a foamable composite resin particle. In one embodiment, the expandable composite water particles comprise a core; Wherein the core comprises an aromatic vinyl resin (a1), a first polyolefin resin (a2), and an inorganic nucleating agent (a3), and the shell is a core / shell type particle comprising a core A polyolefin resin (b1), and a gas barrier resin (b2), wherein the core and the shell are impregnated with the foaming agent (c).

In another embodiment, the expandable composite water particles comprise a core; (A1), a first polyolefin resin (a2) and an inorganic nucleating agent (a3), and the core and the shell are provided with a foaming agent (c) is impregnated, and the foaming agent retention ratio according to the following formula (1) is 85% or more:

[Formula 1]

Blowing agent retention rate (%) = (G1 / G0) 100

(In the above formula (1), G1 is the content of the foaming agent after being left at room temperature and normal pressure for 7 days, 　 G0 is the initial foaming agent content).

In an embodiment, the core may comprise 35 to 85% by weight of the aromatic vinyl resin (a1), 10 to 60% by weight of the first polyolefin resin (a2), and 0.1 to 10% by weight of the inorganic nucleating agent (a3) .

In an embodiment, the core comprises a continuous phase and a dispersed phase, the continuous phase comprises an aromatic vinyl resin (a1), the dispersed phase comprises a first polyolefin resin (a2), and an inorganic nucleating agent (a3) can do.

In an embodiment, the shell may comprise 85 to 99.9% by weight of the second polyolefin-based resin (b1) and 0.1 to 15% by weight of the gas barrier resin (b2).

In an embodiment, the content of the foaming agent (c) may be 3 to 20 parts by weight based on 100 parts by weight of the whole expandable composite resin particles.

In an embodiment, the foamable composite resin particles have an average particle diameter of 0.2 to 1.5 mm, and the weight ratio (core: shell) of the core to the shell may be 1: 0.1 to 0.5.

In an embodiment, the core may further comprise a compatibilizer (a4).

In an embodiment, the expandable composite resin particle may further include at least one of a dispersant and a surfactant.

In the specific example, the expandable composite resin particle may have a blowing agent retention ratio of 85% or more according to the following formula 1:

[Formula 1]

Blowing agent retention rate (%) = (G1 / G0) 100

(In the above formula (1), G1 is the content of the foaming agent after being left at room temperature and normal pressure for 7 days, 　 G0 is the initial foaming agent content).

In another embodiment, the expandable composite resin particle comprises a core; And the core to the shell and the expandable composite resin particles comprising the core / shell-type wrapping, to not less than 85% blowing agent retention ratio by the formula (1), the expandable composite resin particles to 18 from 0.1 to 0.3 kgf / cm vapor of the ^second pressure The compression molded product obtained by prefoaming under the conditions of a density of 22 kg / m ³ and fusing with steam at a pressure of 0.2 to 1 kgf / cm ² has a compressive strength of 1 to 2 kgf / cm ² and a flexural strength of 3 To 5 kgf / cm < ² >

[Formula 1]

Blowing agent retention rate (%) = (G1 / G0) 100

(In the above formula (1), G1 is the content of the foaming agent after being left at room temperature and normal pressure for 7 days, 　 G0 is the initial foaming agent content).

Another aspect of the present invention relates to a method for producing expandable composite resin particles. The method for producing the expandable composite resin particle includes the steps of: preparing a core comprising an aromatic vinyl resin (a1), a first polyolefin resin (a2), and an inorganic nucleating agent (a3); The core and the second polyolefin resin (b1) and the gas barrier resin (b2) are mixed and heated so that a shell formed from the second polyolefin resin (b1) and the gas barrier resin (b2) Forming a core / shell particle of the type; And injecting and impregnating the core / shell particles with the foaming agent (c).

Another aspect of the present invention relates to a foamed molded article. Wherein the expansion-molded article is formed by foaming the expandable composite resin particles.

In the specific examples, the expansion-molded article has a fusion bonding ratio of not less than 70%, a compression strength of 1 to 2 kgf / cm ² , a flexural strength of 3 to 5 kgf / cm ² Can:

[Formula 2]

(%) = 100 x (a) / [(a) + (b)]

(B) is the number of foamed particles that are broken at the interface between the foamed particles, and (b) the number of foamed particles that are broken at the interface between the foamed particles ).

The present invention relates to an expandable composite resin particle having a spherical shape of a core / shell structure, excellent in crack resistance and retainability of a foaming agent, capable of maintaining foamability for a long time and having excellent mold filling property, compressive strength and flexural strength, And an effect of the invention for providing an expanded molded article. The foamed molded article of the present invention is useful as a cushioning material for automobiles as well as a packaging material, agricultural and marine products box, and house insulation material.

1 is a cross-sectional photograph of prefoamed particles obtained by prefoaming foamable composite resin particles produced according to Example 1 of the present invention.

Hereinafter, the present invention will be described in detail.

The foamable composite resin particle according to the present invention is characterized in that it comprises, in one embodiment, a core in the form of spherical particles comprising an aromatic vinyl resin (al), a first polyolefin resin (a2), and an inorganic nucleating agent (a3) A core / shell particle comprising a shell comprising a polyolefin resin (b1) and a gas barrier resin (b2) and enclosing the core, wherein the core and shell are impregnated with the foaming agent (c).

core

The core used in the present invention is, for example, from 35 to 85% by weight of an aromatic vinyl resin (al), from 10 to 60% by weight of a first polyolefin resin (a2) and from 0.1 to 5% by weight of an inorganic nucleating agent (a3) . ≪ / RTI >

In an embodiment, the core may comprise a continuous phase and a dispersed phase, wherein the continuous phase comprises the aromatic vinyl-based resin (al), and the dispersed phase comprises a first polyolefin-based resin (a2) ).

The aromatic vinyl resin (al) used in the present invention is for improving the heat insulation property, expansion ratio, etc., and can be a conventional aromatic vinyl resin. Examples thereof include styrene,? -Methylstyrene, vinyltoluene, Styrene, a mixture thereof, and the like, but the present invention is not limited thereto. Preferably, a polystyrene resin such as general-purpose polystyrene (GPPS) or high-impact polystyrene resin (HIPS), which is a resin obtained by polymerizing the styrene monomer or the like, can be used.

The content of the aromatic vinyl resin (al) is 35 to 85% by weight, preferably 40 to 80% by weight, of the entire cores. In the above range, heat insulation, expansion ratio, rigidity, retainability of foaming agent, storage stability, foam formability and the like can be excellent.

The weight average molecular weight of the aromatic vinyl resin (al) may be, for example, 120,000 to 400,000 g / mol, preferably 150,000 to 350,000 g / mol. The foamability and strength can be maintained within the above range.

The first polyolefin resin (a2) used in the present invention is to improve impact resistance, heat resistance, chemical resistance, and the like. Conventional polyolefin resins can be used. For example, low-density polyethylene (LDPE) Polyethylene resins such as polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-acrylate copolymer and mixtures thereof, polypropylene, Polypropylene resins such as ethylene copolymer, propylene-1-butene copolymer and mixtures thereof, polymers obtained by crosslinking them, blends containing polyisobutene, mixtures thereof, and the like, but are not limited thereto. Preferably, a polyethylene-based resin can be used. For example, the polyethylene melt volume index (MVI) (190 ℃ / 2.16 kg) of the resin may range from 0.5 to 40 g / 10 min, density in the range of 0.86 to 0.97 g / cm ^3, preferably May range from 0.91 to 0.95 g / cm < ³ >.

The content of the first polyolefin-based resin (a2) is 10 to 60 wt%, preferably 15 to 55 wt%, of the total cores. Within the above-mentioned range, foamable composite resin particles having excellent storage stability without damaging elasticity can be obtained, and excellent impact resistance, heat resistance, chemical resistance, oil resistance and the like can be obtained.

As the inorganic nucleating agent (a3) used in the present invention, any inorganic nucleating agent used in conventional foamable resin particles may be used without limitation, and examples thereof include talc, silicon dioxide, mica, clay, zeolite, calcium carbonate, Can be used.

The average particle size of the inorganic nucleating agent (a3) may be 0.1 to 5.0 占 퐉, but is not limited thereto.

The content of the inorganic nucleating agent (a3) is 0.1 to 10% by weight, preferably 0.5 to 5% by weight in the whole core. The rigidity of the expandable composite resin particles can be improved in the above range.

The core improves the compatibility of the aromatic vinyl resin (a1) and the first polyolefin resin (a2) so that the first polyolefin resin (a2) is compatibly dispersed in the aromatic vinyl resin (a1) (A4). As the compatibilizing agent (a4), a common compatibilizer used in mixing an aromatic vinyl resin and a polyolefin resin may be used. Examples of the styrene-butadiene-styrene block copolymer include styrene-butadiene block copolymer, styrene-butadiene block copolymer, styrene-butadiene-styrene block copolymer, styrene-butadiene block copolymer, polybutadiene, polyisoprene, ethylene- Ethylene-propylene block copolymer (SEP), styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene block copolymer - styrene block copolymer (SEPS), hydrogenated butadiene rubber (HSBR), styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), and mixtures thereof. Preferably a styrene-ethylene-butylene-styrene block copolymer (SEBS) and a hydrogenated butadiene rubber (HSBR), more preferably a styrene-ethylene-butylene-styrene block copolymer Can be used.

The content of the compatibilizer (a4) is 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the composite resin component.

Shell

The shell used in the present invention is in the form of enclosing the outside of the core and includes a second polyolefin resin (b1) and a gas barrier resin (b2). For example, the shell may wrap the core continuously or discontinuously, and may preferably cover 90 to 100% of the core surface area.

As the second polyolefin resin (b1) used in the present invention, a conventional polyolefin resin can be used. For example, a low density polyethylene (LDPE), a medium density polyethylene (MDPE), a high density polyethylene (HDPE), a linear low density A polyethylene resin such as a polyethylene (LLDPE), an ethylene-vinyl acetate copolymer (EVA), an ethylene-acrylate copolymer or a mixture thereof, a polypropylene resin, a propylene-ethylene copolymer, a propylene- A mixture thereof, a blend containing polyisobutene, a mixture thereof, and the like, but the present invention is not limited thereto. Preferably, a polyethylene-based resin can be used. For example, the polyethylene melt volume index (MVI) (190 ℃ / 2.16 kg) of the resin may range from 0.5 to 40 g / 10 min, density in the range of 0.86 to 0.97 g / cm ^3, preferably May range from 0.91 to 0.95 g / cm < ³ >.

The content of the second polyolefin-based resin (b1) is 85 to 99.9 wt%, preferably 88 to 99.5 wt%, of the total shell components (b1 + b2). Within the above range, the foaming agent retention and the like of the expandable composite resin particles can be improved.

The gas barrier resin (b2) used in the present invention is for improving the retention of the foaming agent of the expandable composite resin particles, and may be a conventional gas barrier resin. For example, a styrene-acrylonitrile copolymer resin SAN, ethylene vinyl alcohol copolymer resin (EVOH), polyamide resin (PA), polypropylene resin (PP), polyvinyl alcohol resin (PVA), polyacrylonitrile resin (PAN), polyvinyl chloride resin (PVC) , Mixtures thereof, and the like.

The content of the gas barrier resin (b2) is 0.1 to 15% by weight, preferably 0.5 to 12% by weight, based on the entire shell component (b1 + b2). Within the above range, the foaming agent retention and the like of the expandable composite resin particles can be improved.

In the foamable composite resin particle according to the present invention, the core and the shell are impregnated with the foaming agent (c).

As the foaming agent (c) used in the present invention, a conventional volatile foaming agent may be used, and examples thereof include hydrocarbon compounds such as propane, butane, isobutane, pentane, isopentane, cyclopentane, hexane, (HCFC) such as HFC-123 and HFC-123, hydrogen fluoride (HFC) such as HFC-123, fluorohydrocarbons such as a mixture thereof, and mixtures thereof, but are not limited thereto.

The content of the foaming agent (c) is 3 to 20 parts by weight, preferably 5 to 10 parts by weight, based on 100 parts by weight of the whole expandable composite resin particles. And can have a stable foaming property in the above range.

The expandable composite resin particle of the present invention may further include at least one of a dispersant and a surfactant.

As the dispersing agent, a usual dispersing agent may be used without limitation, and for example, a poorly soluble inorganic substance such as calcium trisodium phosphate, magnesium pyrophosphate, magnesium oxide, magnesium chloride, and sodium pyrophosphate may be used. When the dispersant is used, the addition amount may be 0.1 to 3 parts by weight, preferably 0.2 to 2 parts by weight, based on 100 parts by weight of the core.

Examples of the surfactant include surfactants such as polyoxyethylene alkylamine, polyethylene glycol fatty acid ester, alkyldiethanolamide, alkyldiethanolamine, and polyalkylene glycol derivatives. Alkylbenzenesulfonic acid salts such as an alkylsulfonate and sodium alkylbenzenesulfonate, anionic surfactants such as alkylphosphate, cationic surfactants such as aliphatic alkyl quaternary ammonium salts and trialkylbenzylammonium salts, alkyl betaines, alkyl Amphoteric surfactants such as dipotassium phthalate and sodium phthalate, and amidazolium betaine. Further, it is preferable to use a surfactant having a total carbon number of 5 to 20 although it depends on the kind of the surfactant. When the surfactant is used, the addition amount is 0.1 to 2 parts by weight, preferably 0.5 to 1.5 parts by weight based on 100 parts by weight of the core. In this range, antistatic properties can be imparted and tackiness can be prevented, and handling during filling of the mold can be facilitated.

In addition to the above-mentioned dispersant and surfactant, the expandable composite resin particle of the present invention may further contain additives such as foaming auxiliary, antiblocking agent and flame retardant, if necessary.

In the specific examples, the foaming aid facilitates foaming and molding of the foamable composite resin particles, and a conventional foaming aid can be used. For example, a foaming aid such as toluene, cyclohexane, and ethylbenzene can be used have. The amount of the foaming aid to be used may be 2 parts by weight or less based on 100 parts by weight of the whole expandable composite resin particles, but is not limited thereto.

The expandable composite resin particles of the present invention may have an average particle diameter of 0.2 to 1.5 mm, preferably 0.5 to 1.5 mm, but is not limited thereto.

In the specific example, in the foamable composite resin particle, the weight ratio (core: shell) of the core to the shell may be 1: 0.1 to 0.5, preferably 1: 0.2 to 0.4. Within the above range, the foamable composite resin particles may have excellent mechanical properties, moldability, foaming agent retainability, and the like.

The foamable composite water particles according to the present invention have a bubbling agent retention of 85% or more, preferably 89 to 99% according to the following formula (1). If the foaming agent retention ratio is less than 85%, it may be difficult to store the foamable composite water particles for a long time.

[Formula 1]

Blowing agent retention rate (%) = (G1 / G0) 100

(In the above formula (1), G1 is the content of the foaming agent after being left at room temperature and normal pressure for 7 days, 　 G0 is the initial foaming agent content).

In addition, the expandable and then the composite resin particles and 0.1 to 0.3 in kgf / cm vapor of the ^second pressure to the bulk density of the conditions of 18 to 22 ㎏ / ㎥ pre-expanded, and fused by using a vapor of from 0.2 to 1 kgf / cm ² pressure The produced foam molded article may have a compressive strength of 1 to 2 kgf / cm ² and a flexural strength of 3 to 5 kgf / cm ² .

The foamable composite resin particle according to the present invention can be obtained by, for example, (i) a method of extruding a core containing the aromatic vinyl resin (al), the first polyolefin resin (a2) and the inorganic nucleating agent (a3) (B1) and the gas barrier resin (b2) are mixed and heated so that the second polyolefin resin (b1) and the gas Forming a core / shell particle in the form of a shell formed from a barrier resin (b2) surrounding the core, and (iii) injecting and impregnating the core / shell particle with a foaming agent (c) . ≪ / RTI >

In the specific example, the aromatic vinyl resin (al), the first polyolefin resin (a2), and the inorganic nucleating agent (a3) may be added at the same time as the above content at the time of producing the core (step (i)). The extrusion process may be to melt and knead the respective compositions in an extruder, and then to produce spherical particles by an in-water cut method. The extruder is not particularly limited, but in order to obtain a desired grade, The hole diameter of the die plate may be, for example, 0.3 to 2 mm, preferably 0.5 to 1.2 mm. Also, the temperature of the extruder may be 135 to 230 ° C, preferably 150 to 200 ° C, and the temperature of the die plate may be 170 to 350 ° C, preferably 190 to 300 ° C.

Next, in order to form the shell on the outside of the core (step (ii)), for example, the produced core is dispersed in an aqueous medium such as ion-exchanged water, and the second polyolefin- 10 to 50 parts by weight, preferably 20 to 40 parts by weight, of the thermoplastic resin (b1) and the gas barrier resin (b2) are added to 100 parts by weight of the core, and the mixture is stirred and heated at 70 to 130 ° C, And then heated (copolymerized) at 120 ° C to form a shell. In this range, core / shell particles having a weight ratio of the core to the shell of 1: 0.1 to 0.5, preferably 1: 0.2 to 0.4 can be prepared.

When the core is prepared, the compatibilizer (a4) may be further included. When the core is dispersed in an aqueous medium, the dispersant, surfactant, and other additives may be included.

Next, after heating to 105 to 150 ° C, preferably 110 to 135 ° C under atmospheric pressure or 0.5 to 2 kgf / cm ² under nitrogen pressure, the foaming agent (c) is injected into the core / shell The particles may be impregnated with the foaming agent (c) (step (iii)).

The expansion-molded article according to the present invention can be formed by foaming the expandable composite resin particles.

In embodiments, the expandable composite resin particles of the non-charged (introduced) into the airtight mold, for example, 0.1 to 3 at a pressure kgf / cm ² by using a hot air or water vapor (steam), the expandable composite resin particles Can be fused in a mold to produce an expanded molded article. For example, the expandable composite resin particles to be introduced into the mold may be prefoamed particles preliminarily foamed at a predetermined (volumetric) density, for example, 18 to 22 kg / m ³ by heating to a temperature above the softening point temperature.

The pre-expanded beads and the foamed molded article can be easily manufactured by a person having ordinary skill in the art to which the present invention belongs.

In a specific example, the expansion-molded article may have a fusion ratio between expanded particles in the expanded molded article according to the following formula (2): 70% or more, preferably 80 to 100%.

[Formula 2]

(%) = 100 x (a) / [(a) + (b)]

(B) is the number of foamed particles that are broken at the interface between the foamed particles, and (b) the number of foamed particles that are broken at the interface between the foamed particles ).

The compression strength measured by the method described in KS M 3808: 2011 "Expanded polystyrene insulation material" is 1 to 2 kgf / cm ² , preferably 1 to 1.8 kgf / cm ^2. According to KS M ISO 1209-1 The flexural strength measured may be 3 to 5 kgf / cm ² , preferably 3.1 to 4.6 kgf / cm ² .

The foamed molded article of the present invention can be applied to all kinds of packaging materials for household appliances, agricultural and marine products boxes, house insulation materials, etc., and is also useful as a cushioning material for automobiles because of its excellent flame retardance, mechanical strength and heat insulation.

Hereinafter, the present invention will be described in more detail by way of examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Example

Example 1 to 7 and Comparative Example  1 to 6

As the aromatic vinyl-based resin (a1), linear low-density polyethylene (HF-2600 manufactured by Cheil Industries) and first polyolefin-based resin (a2) were used as general-purpose polystyrene (GPPS) TALC (product name: UPN HS-T 0.5, manufactured by: Hayashi Kasei Co., Ltd.) as low-density polyethylene (LDPE, product name: 431G, (SEBS, product name: H1043, manufactured by Asahi Kasei) as a compatibilizing agent (a4) and / or as a compatibilizing agent (a4) were fed to an extruder and melted and kneaded. Spherical cores were prepared. At this time, the average mass of the core was adjusted to about 74 mg. Next, 62 parts by weight of ion-exchanged water, 2 parts by weight of sodium pyrophosphate, and 1 part by weight of sodium alkylbenzenesulfonate were put into a 5 L flask, and the internal temperature was heated to 80 DEG C under a nitrogen stream. Then, a second polyolefin- (Trade name: 4220S manufactured by Samsung Total) or low density polyethylene (LDPE, product name: 431G, manufactured by Samsung Total), and gas barrier resin (b2), as styrene-acrylonitrile (EVOH, product name: EVAL F105B, manufactured by Kuraray Co., Ltd.) was added to the reactor, and the mixture was stirred at 200 rpm for 10 minutes. After agitation, the mixture was heated to 120 DEG C under nitrogen pressure at a pressure of 2 kgf / cm < 2 >, 10 parts by weight of pentane as the foaming agent (c) was injected and impregnated to prepare expandable composite resin particles having a core / shell structure.

Next, the obtained foamable composite resin particles are prefoamed to a bulk density of 18 to 22 kg / m < 3 > at a steam pressure of 0.2 kgf / cm < ² > to prepare prefoamed particles, cm < ² > at a pressure of 10 < ^-2 > Pa. The cross section of the prefoamed particles obtained by prefoaming the foamable composite resin particles produced according to Example 1 was photographed using an optical microscope (model name: VHX-600E, manufacturer: KETENCE) and is shown in Fig.

Example Comparative Example One 2 3 4 5 6 7 One 2 3 4 5 6 (a1) GPPS 64 64 64 64 74 44 68 64 94 94 - - 64 (a2) LLDPE 30 30 - - 50 50 30 30 - - 94 94 - LDPE - - 30 30 - - - - - - - - 30 (a3) Talc 2 2 2 2 2 2 2 2 2 2 2 2 2 (a4) SEBS 4 4 4 4 4 4 - 4 4 4 4 4 4 (b1) LLDPE 30 30 30 30 30 30 30 30 30 30 30 30 30 (b2) EVOH 4 - 4 - 4 4 4 - 4 - 4 - - SAN - 4 - 4 - - - - - 4 - 4 -

Content Unit: parts by weight

Property evaluation method

(1) Content of foaming agent (weight%) of foamable composite resin particles: After standing for 7 days at the time of manufacture and at normal temperature and normal pressure, 20 mg of the foamable composite resin particles was collected and analyzed by gas chromatograph , And the foaming agent retention was evaluated according to the following formula (1).

[Formula 1]

Blowing agent retention rate (%) = (G1 / G0) 100

(In the above formula (1), G1 is the content of the foaming agent after being left at room temperature and normal pressure for 7 days, 　 G0 is the initial foaming agent content)

(2) 5 minutes foaming property (abdomen): The expansion ratio of the expandable composite resin particles obtained by foaming at 0.2 kgf / cm ² steam pressure for 5 minutes was measured.

(3) Bulk density of expanded molded article (kg / m ³ ): The foamed molded article was filled up to 500 cm ³ scale in a 500 cm ³ measuring cylinder, and mass (W, unit: g) Respectively.

[Formula 3]

Bulk density (unit: kg / m ³ ) = W / 500

(4) Fusion ratio (%) of expanded molded article: The surface of a flat plate-like molded article having a length of 400 mm, a width of 300 mm and a thickness of 30 mm was cut along the straight line connecting the centers of a pair of long sides with a cutter knife After inserting a scraper line, the expanded molded article was divided into two by hand according to this deep scraper line. The number of expanded particles (a) broken in the expanded particles with respect to the range of 100 to 150 arbitrary ranges of expanded particles in the fractured surface of the two-divided expanded molded article and the number The number of expanded particles (b) was measured, and the fusion rate was calculated based on the following formula (2).

[Formula 2]

(%) = 100 x (a) / [(a) + (b)]

(B) is the number of foamed particles that are broken at the interface between the foamed particles, and (b) the number of foamed particles that are broken at the interface between the foamed particles )

(5) Evaluation of crack resistance of expanded molded article: A plate-shaped expanded molded article having a length of 215 mm, a width of 40 mm, and a thickness of 20 mm was produced from the expanded molded article, and a steel ball having a constant weight was dropped based on JIS K7211, Unit: cm) was measured.

(6) Compressive strength (kgf / cm ² ): Measured by the method described in KS M 3808: 2011 "expanded polystyrene insulation". 50 mm in width, 50 mm in width and 50 mm in thickness was used, and the test method and calculation were carried out according to the method specified in KS M ISO 844. The load is the load in the yield strain, and the load at the specified strain 0.1 in the case of no yield point up to the specified deformation 0.1. However, the test speed was 10% mm / min of the specimen thickness.

(7) Flexural strength (kgf / cm ² ): Test according to KS M ISO 1209-1. Size, spacing and bending speed of test specimen shall be according to KS M ISO 4898 bending test method. A skin layer in contact with the surface was prepared, and the skin layer was tested so that the pressure bar was in contact. The result of the test was the breaking load (N).

Evaluation items Example Comparative Example One 2 3 4 5 6 7 One 2 3 4 5 6 Foaming
Composite resin
particle Pentane content
(weight%)
Early 8.9 8.8 8.6 8.5 8.9 9.1 8.8 9.1 8.7 8.7 9.0 8.8 9.1 Pentane content
(weight%)
After 7 days 8.3 8.1 8.2 8.2 8.4 8.1 8.1 2.1 8.2 7.9 3.8 3.4 2.5 Pentane retention (%) 93 92 95 96 94 89 92 23 94 91 42 39 28 Expanded molded article 5 minutes foaming (times) 50 50 50 47 60 48 47 10 55 47 20 18 15 Bulk density
(kg / m3) 20 20 20 21 18 19 19 71 18 21 60 65 68 Fusion rate (%) 94 95 97 95 92 98 92 Molding
Impossible 90 92 Molding
Impossible Molding
Impossible Molding
Impossible Crack resistance (cm) 39 36 38 40 35 42 37 24 21 10% Compressive Strength
(kgf / cm2) 1.2 1.1 1.2 1.3 1.6 1.0 1.0 0.5 0.6 Flexural strength
(kgf / cm2) 3.5 3.3 3.5 3.6 3.2 4.1 3.2 1.8 2.0

As shown in Table 2, in the case of Comparative Examples 1 and 6 in which the gas barrier resin was not used, it was found that the foaming agent retention was remarkably lowered to 28% or less, and molding with an expanded molded article was found to be impossible. Further, in Comparative Examples 2 and 3 in which the first polyolefin-based resin was not used for the core, the compressive strength, flexural strength, crack resistance and the like of the expanded molded article were found to be lowered and the use of an aromatic vinyl- In the case of Comparative Examples 4 and 5, in which the foaming agent retention was lowered, it was found that molding with an expanded molded article was impossible. On the other hand, in the case of Examples 1 to 7 according to the present invention, the foaming agent (pentane) retention ratio of the expandable resin particles is as high as 89% or more, and the foaming properties, the fusion ratio (filling property), the cracking resistance, Strength and the like are excellent.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (14)

core; And a core / shell-shaped particle composed of a shell surrounding the core,
Wherein the core comprises an aromatic vinyl resin (a1), a first polyolefin resin (a2), and an inorganic nucleating agent (a3)
Wherein the shell comprises a second polyolefin-based resin (b1), and a gas barrier resin (b2)
Wherein the core and the shell are impregnated with the foaming agent (c).
core; And a core / shell-shaped particle composed of a shell surrounding the core,
Wherein the core comprises an aromatic vinyl resin (a1), a first polyolefin resin (a2) and an inorganic nucleating agent (a3)
The core and the shell are impregnated with the foaming agent (c)
A foamable composite resin particle having a foaming agent retention of 85% or more according to the following formula 1:
[Formula 1]
Blowing agent retention rate (%) = (G1 / G0) 100
(In the above formula (1), G1 is the content of the foaming agent after being left at room temperature and normal pressure for 7 days, 　 G0 is the initial foaming agent content).
The core according to any one of claims 1 to 3, wherein the core comprises 35 to 85% by weight of the aromatic vinyl resin (a1), 10 to 60% by weight of the first polyolefin resin (a2) 0.1 to 10% by weight based on the total weight of the foamable composite resin particles.
The method according to any one of claims 1 and 2, wherein the core comprises a continuous phase and a dispersed phase, the continuous phase comprises an aromatic vinyl-based resin (a1), and the dispersed phase comprises a first polyolefin- ), And an inorganic nucleating agent (a3).
The gas barrier resin composition according to any one of claims 1 to 5, wherein the shell comprises 85 to 99.9% by weight of the second polyolefin resin (b1) and 0.1 to 15% by weight of the gas barrier resin (b2) Foamable composite resin particle.
The foamable composite resin particle according to any one of claims 1 and 2, wherein the content of the foaming agent (c) is 3 to 20 parts by weight based on 100 parts by weight of the whole expandable composite resin particles.
The foamable composite resin particle according to any one of claims 1 and 2, wherein the average particle diameter of the foamable composite resin particle is 0.2 to 1.5 mm, and the weight ratio (core: shell) of the core to the shell is 1: 0.1 to 0.5 By weight.
The foamable composite resin particle according to any one of claims 1 and 2, wherein the core further comprises a compatibilizing agent (a4).
The foamable composite resin particle according to any one of claims 1 and 2, wherein the expandable composite resin particle further comprises at least one of a dispersant and a surfactant.
The foamable composite resin particle according to claim 1, wherein the foamable composite resin particle has a foaming agent retention ratio of 85% or more according to the following formula 1:
[Formula 1]
Blowing agent retention rate (%) = (G1 / G0) 100
(In the above formula (1), G1 is the content of the foaming agent after being left at room temperature and normal pressure for 7 days, 　 G0 is the initial foaming agent content).
core; And a shell surrounding the core, wherein the foamed composite resin particle is a core / shell type foamable composite resin particle,
The foaming agent retention ratio according to the following formula 1 is 85% or more,
The foaming then the composite resin particles, a preliminary to a volume density of 18 to 22 ㎏ / ㎥ 0.1 to 0.3 kgf / cm vapor of ^two pressure foam, the foam produced by fusion, using a vapor of from 0.2 to 1 kgf / cm ² pressure Wherein the compact has a compressive strength of 1 to 2 kgf / cm ² and a flexural strength of 3 to 5 kgf / cm ² .
[Formula 1]
Blowing agent retention rate (%) = (G1 / G0) 100
(In the above formula (1), G1 is the content of the foaming agent after being left at room temperature and normal pressure for 7 days, 　 G0 is the initial foaming agent content).
A process for producing a core comprising an aromatic vinyl resin (a1), a first polyolefin resin (a2), and an inorganic nucleating agent (a3);
Mixing the core with the second polyolefin resin (b1) and the gas barrier resin (b2), and heating the core / shell particle (b2) to form a shell formed from the second polyolefin resin and the gas barrier resin, ; And
And injecting and impregnating the core / shell particles with the foaming agent (c).
A foamed molded article formed by foaming foamable composite resin particles according to any one of claims 1 to 3.
The foamed molded article according to claim 13, wherein said foamed molded article has a fusion bonding ratio of foamed particles in the expanded molded article according to the following formula 2: 70% or more, a compressive strength of 1 to 2 kgf / cm ² , a flexural strength of 3 to 5 kgf / ^{2. The} foamed molded article according to claim ¹ ,
[Formula 2]
(%) = 100 x (a) / [(a) + (b)]
(B) is the number of foamed particles that are broken at the interface between the foamed particles, and (b) the number of foamed particles that are broken at the interface between the foamed particles ).

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