KR20240015385A - Expandable resin composition, method for preparing the same and foamed molded article produced therefrom - Google Patents

Abstract

The foamable resin composition of the present invention includes 100 parts by weight of polypropylene; 5 to 15 parts by weight of zinc oxide; and 15 to 35 parts by weight of a polyolefin-polyalkylene oxide block copolymer; a foam produced by foaming such that the foaming ratio is 5 to 20 times and the average cell size is 50 to 400 ㎛. It is characterized in that it is in the form of particles. The foamable resin composition has excellent anti-fungal properties, extrusion properties, moldability, etc.

Description

Foamable resin composition, manufacturing method thereof, and foam molded article manufactured therefrom {EXPANDABLE RESIN COMPOSITION, METHOD FOR PREPARING THE SAME AND FOAMED MOLDED ARTICLE PRODUCED THEREFROM}

The present invention relates to a foamable resin composition, a method for producing the same, and a foam molded article manufactured therefrom. More specifically, the present invention relates to a foamable resin composition having excellent anti-fungal properties, extrudability, moldability, etc., a manufacturing method thereof, and a foam molded article manufactured therefrom.

The foamable resin composition can be manufactured into a foamable resin composition in the form of foamed particles by putting it in a high-pressure reactor along with water, using carbon dioxide gas, etc. as a foaming agent, and discharging under reduced pressure under certain temperature and pressure conditions. The produced foamed particles can be molded into a mold. It can be manufactured into a molded product (foam molded body) by filling, heating and fusing it. The molded products manufactured in this way are excellent in high strength, lightness, cushioning, waterproofing, heat retention, and insulation, and are used in various fields such as packaging materials for home appliances, boxes for agricultural and marine products, father and son, and insulation materials for building materials.

In order to impart anti-fungal properties to the polyolefin-based foamable resin composition, a high content of an anti-fungal additive of about 20 parts by weight or more must be added per 100 parts by weight of the polyolefin resin. However, existing anti-fungal additives may not be suitable for the foamable resin composition manufacturing process due to specific gravity issues, and when a high content of anti-fungal additives is added to the foamable resin composition, surface roughness or disconnection occurs when the foamable resin composition is extruded. phenomenon may occur, and there is a risk that the adhesion of foamed particles of polyolefin resin may decrease due to the high inorganic content.

Therefore, there is a need to develop a foamable resin composition that has excellent anti-fungal properties, extrudability, and moldability (foam particle adhesion).

The background technology of the present invention is disclosed in Korean Patent Registration No. 10-0833453, etc.

The purpose of the present invention is to provide a foamable resin composition with excellent anti-fungal properties, extrudability, moldability, etc.

Another object of the present invention is to provide a method for producing the foamable resin composition.

Another object of the present invention is to provide a foam molded article formed from the foamable resin composition.

The above and other objects of the present invention can all be achieved by the present invention described below.

1. One aspect of the present invention relates to a foamable resin composition. The foamable resin composition includes 100 parts by weight of polypropylene; 5 to 15 parts by weight of zinc oxide; and 15 to 35 parts by weight of a polyolefin-polyalkylene oxide block copolymer; a foam produced by foaming such that the foaming ratio is 5 to 20 times and the average cell size is 50 to 400 ㎛. It is characterized in that it is in the form of particles.

2. In the first embodiment, the polypropylene may include one or more of propylene homopolymer, propylene-ethylene random copolymer, and ethylene-propylene copolymer.

3. In the first or second embodiment, the zinc oxide may have an average particle size of 100 to 300 nm and a specific surface area BET of 5 to 15 m ² /g.

4. In embodiments 1 to 3, the polyolefin-polyalkylene oxide block copolymer may have a melting point of 115 to 150°C, and the flow rate measured at 190°C and a load of 21.18 N according to ASTM D1238. The melt-flow index may be 5 to 50 g/10 min.

5. In embodiments 1 to 4, the weight ratio of the zinc oxide and the polyolefin-polyalkylene oxide block copolymer may be 1:1.5 to 1:5.

6. In embodiments 1 to 5, the foamable resin composition was inoculated with mold spores in an injection specimen measuring 5 cm × 5 cm according to the ISO 846B evaluation method, and cultured for 28 days at 29°C and RH 95% The anti-fungal rating measured after use may be 2 or lower.

7. Another aspect of the present invention relates to a method for producing a foamable resin composition. The manufacturing method includes mixing a dispersion medium containing water and a dispersant with a thermoplastic resin composition containing 100 parts by weight of polypropylene, 5 to 15 parts by weight of zinc oxide, and 15 to 35 parts by weight of a polyolefin-polyalkylene oxide block copolymer to form a mixture. manufacturing; And it is characterized by including the step of adding a foaming agent to the mixture and foaming the mixture so that the foaming ratio is 5 to 20 times and the average cell size is 50 to 400 ㎛.

8. In the 7th embodiment above, the foaming is heating and pressurizing the mixture into which the foaming agent is added to a temperature condition of 130 to 160 ° C. and a pressure condition of 20 to 50 kgf / cm ² and then exposing it to room temperature and atmospheric pressure conditions. You can.

9. Another aspect of the present invention relates to a foam molded body. The foam molded body is characterized in that it is formed by filling a mold with the foamable resin composition according to any one of 1 to 6 above, followed by heating and fusing.

The present invention has the effect of providing a foamable resin composition with excellent anti-fungal properties, extrudability, moldability, etc., a method for producing the same, and a foam molded article manufactured therefrom.

Hereinafter, the present invention will be described in detail as follows.

The foamable resin composition according to the present invention includes (A) polypropylene; (B) zinc oxide; and (C) a polyolefin-polyalkylene oxide block copolymer.

In this specification, “a to b” indicating a numerical range is defined as “≥a and ≤b”.

(A) Polypropylene

Polypropylene according to one embodiment of the present invention is a base resin for forming a foamable resin composition and a foam molded body, and includes propylene homopolymer; propylene-ethylene random copolymer; An ethylene-propylene copolymer in which the propylene homopolymerization portion and the ethylene-propylene copolymerization portion are stepwise polymerized in a reactor; Or it may include a combination thereof. For example, propylene-ethylene random copolymer can be used.

In a specific example, the polypropylene has a melt-flow index measured at 230°C and a load of 2.16 kg according to ASTM D1238 of 1 to 50 g/10 minutes, for example, 5 to 30 g/ It could be 10 minutes. Within the above range, the mechanical strength, moldability, foamability, etc. of the foamable resin composition may be excellent.

(B) Zinc oxide

Zinc oxide according to one embodiment of the present invention is applied together with a polyolefin-polyalkylene oxide block copolymer, without deteriorating the mechanical properties of the polyolefin-based foamable resin composition and the foam molded body, and anti-fungal properties, extrudability, and moldability. As a possible improvement, zinc oxide used in ordinary thermoplastic resin compositions can be used.

In a specific example, the zinc oxide has an average particle size (D50) measured using a particle size analyzer (Beckman Coulter, Laser Diffraction Particle Size Analyzer LS I3 320 equipment) of 100 to 300 nm, for example, 120 to 200 nm. You can. In addition, the zinc oxide has a specific surface area BET measured with a BET analysis equipment (Micromeritics, Surface Area and Porosity Analyzer ASAP 2020 equipment) using a nitrogen gas adsorption method of 5 to 15 m ² /g, for example, 8 to 12. It may be m ² /g, and the purity may be 99% or more. Within the above range, the foamable resin composition may have excellent anti-fungal properties, extrudability, moldability, etc.

In a specific example, the zinc oxide may be included in an amount of 5 to 15 parts by weight, for example, 5.5 to 14.5 parts by weight, based on 100 parts by weight of the polypropylene. If the zinc oxide content is less than 5 parts by weight based on 100 parts by weight of propylene, there is a risk that the anti-fungal properties of the foamable resin composition may decrease, and if it exceeds 15 parts by weight, the anti-fungal properties of the foamable resin composition may decrease. There is a risk that extrudability, moldability (foamed particle adhesion), and mechanical properties may deteriorate.

(C) Polyolefin-polyalkylene oxide block copolymer

The polyolefin-polyalkylene oxide block copolymer according to one embodiment of the present invention is applied together with zinc oxide, without deteriorating the mechanical properties of the polyolefin-based foamable resin composition and the foam molded product, and has anti-fungal properties, extrudability, and moldability. etc. can be improved.

In a specific example, the polyolefin-polyalkylene oxide block copolymer can be polymerized by a known polymerization method, and contains 10 to 90% by weight of polyolefin block, for example, 20 to 80% by weight and 10 to 90% by weight of polyalkylene oxide block. It may include weight percent, for example 20 to 80 weight percent. Within the above range, the thermoplastic resin composition may have excellent antistatic properties, etc.

In a specific example, the polyolefin-polyalkylene oxide block copolymer may have a melting point of 115 to 150°C, for example, 115 to 140°C. Within the above range, the moldability (foamed particle fusion property) of the foamable resin composition can be excellent, and the structure of the foam molded product can be maintained.

In a specific example, the polyolefin-polyalkylene oxide block copolymer has a melt-flow index of 5 to 50 g/10 min, measured under load conditions of 190°C and 21.18 N, according to ASTM D1238. For example, it may be 10 to 40 g/10 minutes. Within the above range, the moldability (foamed particle adhesion), etc. of the foamable resin composition may be excellent.

In a specific example, the polyolefin-polyalkylene oxide block copolymer may be included in an amount of 15 to 35 parts by weight, for example, 20 to 30 parts by weight, based on 100 parts by weight of the polypropylene. If the content of the polyolefin-polyalkylene oxide block copolymer is less than 15 parts by weight based on 100 parts by weight of propylene, there is a risk that the anti-fungal properties and moldability (foamed particle adhesion) of the foamable resin composition may be reduced. , if it exceeds 35 parts by weight, there is a risk that the anti-fungal properties, extrudability, etc. of the foamable resin composition may decrease.

In a specific example, the weight ratio of the zinc oxide and the polyolefin-polyalkylene oxide block copolymer (zinc oxide: polyolefin-polyalkylene oxide block copolymer) is 1:1.5 to 1:5, for example, 1:1.6 to 1:1.6. It could be 1:4.7. Within the above range, the foamable composition may have better anti-fungal properties, extrudability, moldability, etc.

The foamable resin composition according to one embodiment of the present invention has a foaming ratio of 5 to 20 times that of the thermoplastic resin composition containing polypropylene, zinc oxide, and polyolefin-polyalkylene oxide block copolymer, and the average cell It may be in the form of foamed particles manufactured by foaming to a size of 50 to 400 ㎛.

In an embodiment, the thermoplastic resin composition is obtained by mixing the components and melt-extruding the composition at 150 to 240° C., for example, 160 to 230° C., using a conventional single-screw or twin-screw extruder, to obtain a weight of 0.8 to 1.4 mg and a diameter of 0.5 mg. It may be in the form of a cylindrical pellet with a size of 0.5 to 1.5 mm and a height of 0.5 to 1.5 mm.

In a specific example, the foamable resin composition (foamed particles) may have a foaming ratio of 5 to 20 times, for example, 10 to 15 times, and an average cell size of 50 to 400 ㎛, for example, 100 to 350 ㎛. there is. Within the above range, the moldability (foamed particle adhesion), mechanical properties, etc. of the foamed particles (foamed molded body) may be excellent. Here, the foaming ratio of the foamed particles can be measured by a direct immersion method. In detail, the weight and volume of the dried foamed particles are measured using a measuring cylinder and scale to calculate the density of the particles, and then the resin composition before foaming. It is a value converted by multiplying the particle density of 0.9 g/cm ³ by 1, and the average size of the cell is calculated by cooling the foamed particles with liquid nitrogen, cutting a cross section, and measuring the cells of the foamed particles using a SEM (Scanning Electron Microscope). This value is obtained by measuring five or more diameters (sizes) and then calculating the average value.

The foamable resin composition according to one embodiment of the present invention may further include additives used in conventional foamable resin compositions to the extent that they do not impair the purpose and effect of the present invention. Examples of the additive include, but are not limited to, antioxidants, light stabilizers, heat stabilizers, flame retardants, colorants, plasticizers, slip agents, and combinations thereof. When using the additive, its content may be 0.001 to 40 parts by weight, for example, 0.1 to 10 parts by weight, based on 100 parts by weight of polypropylene.

The foamable resin composition according to one embodiment of the present invention was measured by inoculating mold spores into an injection specimen measuring 5 cm The anti-fungal rating may be 2 or lower (grade 0, 1 or 2).

The foamable resin composition according to one embodiment of the present invention may be manufactured according to a known method for producing foamed particles. For example, preparing a mixture by mixing the thermoplastic resin composition with a dispersion medium containing water and a dispersant; Then, it can be manufactured by adding a foaming agent to the mixture and foaming it to have the foaming ratio and the average size of the cells.

In an embodiment, the dispersant may include one or more of higher fatty acids, higher fatty acid esters, and higher fatty acid amides.

In an embodiment, the resin composition may be introduced into a reactor in which a dispersion medium is present, or a dispersion medium may be introduced into the reactor together with the resin composition to form a mixture.

In a specific example, the foaming agent may be a foaming agent used in conventional foam particles, for example, carbon dioxide, propane, butane, hexane, pentane, heptane, cyclobutane, cyclohexane, methyl chloride, ethyl chloride, and methylene. Chloride, dimethyl ether, diethyl ether, methyl ethyl ether, nitrogen, argon, etc. can be used alone or in a mixture of two or more.

In a specific example, the foaming is performed by subjecting the mixture to which the foaming agent is added under temperature conditions of 130 to 160°C, for example, 135 to 155°C, and pressure conditions of 20 to 50 kgf/cm ² , for example, 25 to 40 kgf/cm ² This can be done by heating and pressurizing and then exposing to room temperature and atmospheric pressure conditions. Under the above temperature and pressure conditions, foamed particles (foamable resin composition) having a foaming ratio of 5 to 20 times and an average cell size of 50 to 400 ㎛ can be obtained.

In a specific example, the foamed particles (foamable resin composition) may have an average particle diameter measured with a vernier caliper of 1 to 7 mm, for example, 2 to 6 mm, but is not limited thereto. Within the above range, moldability, etc. may be excellent.

The foam molded body according to the present invention can be formed by filling the foamable resin composition (foamed particles) into a mold and fusing it, and can be easily manufactured by those skilled in the art. For example, the foam molded body is filled (introduced) with the foam particles into a non-hermetic mold, and saturated steam (e.g., saturated steam at a pressure of 2.0 to 3.5 bar) is supplied to the mold for about 30 seconds, It can be manufactured by fusing the foamed particles together and drying them. Since the foam molded body has excellent anti-fungal properties and mechanical properties, it can be mainly used for automobiles such as energy absorbers and tool boxes, and for consumer goods it is used as packaging materials, fillers for bean bags, toys, and multi-purpose products. It can be used in mats, Pilates equipment, and thermal insulation materials for water purifiers.

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

Example

Hereinafter, the specifications of each component used in the examples and comparative examples are as follows.

(A) Polypropylene

Propylene-ethylene random copolymer (manufacturer: Lotte Chemical, product name: SEP-550) was used.

(B) Zinc oxide

Zinc oxide (manufacturer: Taekyung SBC, product name: KS1(F)) with an average particle size of 150 nm and a specific surface area BET of 10 m ² /g was used.

(C) Polyolefin-polyalkylene oxide block copolymer

Polypropylene-polyethylene oxide block copolymer (PP-b-PEO, manufacturer: Sanyo chemical, product name: PELECTRON PVL) was used.

Examples 1 to 5 and Comparative Examples 1 to 4

Each of the components was added in the amounts shown in Tables 1 and 2 below, and then extruded at 190°C to prepare a thermoplastic resin composition (1 to 1.2 mg, in the form of a pellet with a diameter of 0.7 mm × thickness of 1 mm). For extrusion, a single-screw extruder (screw rotation speed: 360 rpm) with L/D = 40 and a diameter of 39.8 mm was used.

Next, 100 parts by weight of the thermoplastic resin composition was added to an autoclave along with 300 parts by weight of a dispersion medium (water to which a dispersant was added). After carbon dioxide (CO ₂ ), a foaming agent, was added to the autoclave, the temperature and pressure inside the autoclave were adjusted to 145.5°C and 28 kg/cm ² while stirring. Next, the contents of the autoclave were exposed to the air to prepare foamed particles (foamable resin composition, foaming ratio 11 times, foam cell average size: 150 ㎛). The foamed particles were dried at room temperature for 24 hours, then placed in a pressurized tank and pressurized from atmospheric pressure (1 bar) to 3 bar over 10 hours, and then filled into a mold (450 mm × 450 mm × 50 mm). Afterwards, 2.5 bar of saturated steam was supplied to the mold for 30 seconds, the foam particles were fused together, cooled, taken out, and dried in a convection oven at 60°C for 24 hours to prepare a foam molded body. The physical properties of the manufactured foam molded body were evaluated by the following method, and the results are shown in Tables 1 and 2 below.

How to measure physical properties

(1) Anti-fungal evaluation: According to the ISO 846B evaluation method, mold spores were inoculated into an injection specimen measuring 5 cm The fungal rating was measured.

(Grade 0: No mold even with a microscope (50x magnification), Grade 1: No mold visible to the naked eye, but clearly visible under a microscope, Grade 2: Mold clearly visible to the naked eye (less than 25% of the specimen surface) , Grade 3: Mold clearly visible to the naked eye (less than 50% of the specimen surface), Grade 4: Significant mold growth observed (more than 50% of the specimen surface), Grade 5: Mold growth covering the entire specimen surface.

(2) Extrudability evaluation: When extruding the thermoplastic resin composition, the surface of the strand was visually inspected, and it was judged to be ‘good’ to the extent that lumps (protrusions) occurred, and if strand breaks occurred, it was judged to be ‘bad’. Judgment was made.

(3) Evaluation of moldability (foam particle adhesion): Fix both ends of a molded product (450 mm After bending and crushing, the cross-section was photographed under a microscope (OLYMPUS, SZH10, Specifically, when the foam is observed to be cracked or split on the fractured surface of the molded product, the moldability (foam particle adhesion) is judged to be 'good', and when the surface of the foam is observed to be exposed on the fractured surface. , the moldability (foam particle adhesion) was judged to be ‘poor’.

Example One 2 3 4 5 (A) (parts by weight) 100 100 100 100 100 (B) (part by weight) 5.5 10 14.5 10 10 (C) (parts by weight) 25 25 25 20 30 Anti-mold rating 2 0 0 0 0 Formability Good Good Good Good Good extrudability Good Good Good Good Good

Comparative example One 2 3 4 (A) (parts by weight) 100 100 100 100 (B) (part by weight) 4 16 10 10 (C) (parts by weight) 25 25 14 36 Anti-mold rating 4 3 4 3 Formability Good error error Good extrudability Good error Good error

From the above results, it can be seen that the foamable resin composition of the present invention is excellent in anti-fungal properties, extrudability, moldability (foamed particle fusion properties, etc.), etc.

On the other hand, in the case of Comparative Example 1, where a small amount of zinc oxide was used, anti-fungal properties, etc. were found to be reduced, and in the case of Comparative Example 2, where an excessive amount of zinc oxide was used, anti-fungal properties, extrudability, and moldability (foamed particle fusion properties) were decreased. It can be seen that the back has deteriorated. In addition, in the case of Comparative Example 3, in which a small amount of polyolefin-polyalkylene oxide block copolymer was used, it can be seen that anti-fungal properties and moldability (foamed particle adhesion), etc. were reduced, and the polyolefin-polyalkylene oxide block copolymer In the case of Comparative Example 4 where excessive amounts were used, it can be seen that anti-fungal properties, extrudability, etc. were reduced.

So far, the present invention has been examined focusing on the embodiments. A person skilled in the art to which the present invention pertains will understand that the present invention can be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative rather than a restrictive perspective. The scope of the present invention is indicated in the claims rather than the foregoing description, and all differences within the equivalent scope should be construed as being included in the present invention.

Claims (9)

100 parts by weight of polypropylene; 5 to 15 parts by weight of zinc oxide; and 15 to 35 parts by weight of a polyolefin-polyalkylene oxide block copolymer;
A foamable resin composition characterized in that it is in the form of foamed particles manufactured by foaming so that the foaming ratio is 5 to 20 times and the average cell size is 50 to 400 ㎛.
The foamable resin composition according to claim 1, wherein the polypropylene includes at least one of propylene homopolymer, propylene-ethylene random copolymer, and ethylene-propylene copolymer.
The foamable resin composition of claim 1, wherein the zinc oxide has an average particle size of 100 to 300 nm and a specific surface area BET of 5 to 15 m ² /g.
The method of claim 1, wherein the polyolefin-polyalkylene oxide block copolymer has a melting point of 115 to 150°C, and a melt-flow index measured under load conditions of 190°C and 21.18 N according to ASTM D1238. ) A foamable resin composition, characterized in that 5 to 50 g/10 minutes.
The foamable resin composition according to claim 1, wherein the weight ratio of the zinc oxide and the polyolefin-polyalkylene oxide block copolymer is 1:1.5 to 1:5.
The method of claim 1, wherein the foamable resin composition is measured by inoculating fungal spores into an injection specimen measuring 5 cm A foamable resin composition characterized by a mold resistance rating of 2 or less.
A mixture is prepared by mixing a dispersion medium containing water and a dispersant with a thermoplastic resin composition containing 100 parts by weight of polypropylene, 5 to 15 parts by weight of zinc oxide, and 15 to 35 parts by weight of a polyolefin-polyalkylene oxide block copolymer; and
A method for producing a foamable resin composition, comprising the step of adding a foaming agent to the mixture and foaming the mixture so that the foaming ratio is 5 to 20 times and the average cell size is 50 to 400 ㎛.
The method of claim 7, wherein the foaming is performed by heating and pressurizing the mixture containing the foaming agent to a temperature of 130 to 160° C. and a pressure of 20 to 50 kgf/cm ² and then exposing the mixture to room temperature and atmospheric pressure. A method of producing a foamable resin composition.
A foam molded article, which is formed by filling a mold with the foamable resin composition according to any one of claims 1 to 6, followed by heating and fusing.