KR101919994B1 - Flame retardant foam and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a flame-retardant foam and a method for manufacturing the same. More particularly, the present invention relates to a flame-retardant foam which is excellent in durability, excellent in heat insulation, low in gas harmfulness after product incineration, environmentally-friendly, and also has remarkably high flame retardancy, without using harmful foaming gas causing global warming when manufacturing the foam, and a method for manufacturing the same.

Description

FIELD OF THE INVENTION The present invention relates to flame retardant foam,

More particularly, the present invention relates to a flame-retardant foam and a method for producing the same, and more particularly, to a flame-retarded foam and a method for producing the same, Friendly flame retardant foam and a method for producing the same.

BACKGROUND ART Conventionally, foams made of a synthetic resin as a raw material are widely used as cushioning materials, insulating materials, or heat insulating materials. However, in the case of a foam made of only a synthetic resin, there is a problem that not only the harmful foam gas is used at the time of manufacturing but also it is not easily decomposed by microorganisms existing in nature when it is disposed of after use, Causing global warming and environmental problems.

In addition, when the incinerator is incinerated, there is a problem that the incinerator is easily damaged because the heat generated is high. In addition, polystyrene-based plastic foams have been pointed out in addition to the above-mentioned problems, in which environmental hormones are specifically generated.

In recent years, in order to solve the above-mentioned problems, development is progressing to produce a foam through an environmentally friendly material which is easily biodegradable. However, in the case of a foam produced by using an eco-friendly material which is easy to be biodegraded in the past, it could serve as a heat insulator, but it had a problem of insufficient flame retardancy.

Accordingly, it is urgently required to develop a flame retardant foam which is low in gas harmfulness, excellent in durability, excellent in heat insulation property, and environmentally friendly as well as remarkably excellent in flame retardancy.

KR 10-2006-0083990 A (Released: July 21, 2006)

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior arts, and an object of the present invention is to provide a flame retardant foam which is low in gas toxicity, excellent in durability, excellent in heat insulation properties,

In order to solve the above-mentioned problems, the present invention provides a flame retarded foam comprising 65 to 200 parts by weight of a starch, 65 to 300 parts by weight of a polymer, and 15 to 175 parts by weight of a flame retardant, based on 100 parts by weight of a cellulose-based powder.

According to an embodiment of the present invention, the cellulose-based powder may include paper powder.

The cellulose-based powder may have an average particle diameter of 500 mu m or less.

The starch may have a water content of 20% or less.

The polymer may include one or more selected from the group consisting of polyolefin-based, polyamide-based, polyester-based, acrylonitrile-butadiene-styrene, and polylactic acid.

In addition, the flame retardant may include at least one selected from the group consisting of polyphenylene sulfide (PPS) and meta-aramid (m-Aramid).

The flame retardant may include polyphenylene sulfide (PPS) and meta-aramid (m-aramid) in a weight ratio of 1: 0.5 to 2.

The flame retardant may have an average particle size of 120 탆 or less.

In addition, the total heat emission amount measured by the following measuring method 1 may be 8 MJ / m 2 or less.

[Measurement method 1]

The total heat release was measured by a cone calorimeter method according to KSF ISO 5660-1 under the conditions of a temperature of 23 캜 and a relative humidity (RH) of 50%.

Further, the time in which the heat release rate measured by the following measurement method 2 continuously exceeds 200 kW / m 2 may be 10 seconds or less.

[Measurement method 2]

Under the conditions of a temperature of 23 캜 and a relative humidity (RH) of 50%, the time at which the heat release rate continuously exceeded 200 kW / m 2 by a cone calorimeter method according to KSF ISO 5660-1 was measured.

Further, the average behavior stopping time measured by the following measurement method 3 may be 8 minutes or more.

[Measuring method 3]

The average behavior downtime was measured by a gas hazard test method based on KSF 2271 under the conditions of a temperature of 23 ° C and a relative humidity (RH) of 50%.

According to another aspect of the present invention, there is provided a method for preparing a cellulose-based powder, which comprises mixing 65 to 200 parts by weight of a starch and 15 to 175 parts by weight of a flame retardant with respect to 100 parts by weight of a cellulose- Pelletizing the mixture; And a step of subjecting the pelletized mixture to treatment with 65 to 300 parts by weight of a polymer polymer based on 100 parts by weight of the cellulose-based powder, followed by extrusion foaming.

According to an embodiment of the present invention, the water content of the mixture may be dried to 10 to 25% in the step of pelletizing.

Also, the extrusion foaming step may be carried out through a pressure starting aeration having four to six separate cylinders having a predetermined temperature gradient.

Further, the method may further include aging after the extrusion foaming step.

The flame-retarded foamed product of the present invention and the method of producing the same have an effect of less gas harmfulness, excellent durability, excellent heat-insulating property, eco-friendly property and flame retardancy remarkably excellent.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

The flame-retarded foam according to an embodiment of the present invention includes cellulose-based powder, starch, high-molecular polymer, and flame-retardant material.

First, the cellulose-based powder will be described.

The cellulose-based powder may be any material that can be used as a powder that imparts environmental friendliness and good regeneration to the foam in the art, and is preferably a paper powder, a coffee slurry, a by-product of wood, And more preferably paper powder may be advantageous for the effect of less gas harmfulness and excellent flame retardancy.

The cellulose-based powder may have an average particle size of 500 탆 or less, preferably 350 탆 or less, and more preferably 300 탆 or less. If the average particle diameter of the cellulose-based powder exceeds 500 탆, the heat insulating property and the flame retardancy may be lowered.

Next, the starch will be described.

The starch may be uniformly and stably foamed in the production of a flame-retardant foam, and may be any starch that can be used in the art without limitation, and preferably at least one selected from the group consisting of natural starch and modified starch But are not limited thereto.

The starch may have a water content of 20% or less, preferably 17% or less, more preferably 15% or less, and still more preferably 13.5% or less. If the moisture content of the starch exceeds 20%, uniform foaming may not be easy.

The starch is contained in an amount of 65 to 200 parts by weight, preferably 80 to 180 parts by weight, based on 100 parts by weight of the cellulose-based powder. If the starch is less than 65 parts by weight with respect to 100 parts by weight of the foamable powder, uniform and stable foaming is not easy. If the starch is more than 200 parts by weight, foamability, heat insulation and processability may be deteriorated.

Next, the above polymer polymer will be described.

The polymer polymer serves as a binder of the flame-retardant foam, and any polymer that can be used in the art can be used without limitation. Preferably, the polymer is a polyolefin-based, polyamide-based, At least one selected from the group consisting of polyester-based, acrylonitrile-butadiene-styrene and polylactic-acid including polybutylene terephthalate and / or polyethylene terephthalate, and more preferably modified polyolefin polymer May be more advantageous for the stable foaming and the role of the binder of the polyolefin polymer.

The polyolefin polymer may be included in an amount of 65 to 300 parts by weight, preferably 80 to 260 parts by weight, based on 100 parts by weight of the cellulose-based powder. If the content of the polyolefin polymer is out of the above range, the foaming property may be deteriorated and the heat insulating property may not be good.

Next, the flame retardant will be described.

The flame retardant may be any of flame retardant materials conventionally used in the art, and preferably polyphenylene sulfide (PPS) and meta-aramid m-Aramid). < / RTI >

When the flame retardant includes both polyphenylene sulfide (PPS) and meta-aramid, the weight ratio of polyphenylene sulfide (PPS) and meta-aramid (m-Aramid) is 1: 0.5 to 2 Can be 1: 0.7 to 1.5. If the weight ratio of the polyphenylene sulfide (PPS) and the meta-aramid (m-Aramid) does not satisfy the above range, the total heat emission amount according to the measuring method 1 described later can be increased. The average action stop time may be shortened.

Further, the flame retardant may have an average particle size of 120 탆 or less, and preferably an average particle size of 100 탆 or less. If the average particle diameter of the flame retardant exceeds 120 탆, the flame retardancy may deteriorate.

The flame retardant may be included in an amount of 15 to 175 parts by weight, preferably 25 to 160 parts by weight, based on 100 parts by weight of the cellulose-based powder. If the amount of the flame retardant is less than 15 parts by weight based on 100 parts by weight of the cellulose-based powder, the flame retardancy may be lowered. If the amount is more than 175 parts by weight, the foamability and heat insulating property may be deteriorated.

Meanwhile, the flame-retarded foam according to the present invention may have a total heat emission amount measured by the following measurement method 1 of 8 MJ / m 2 or less, preferably 7.7 MJ / m 2 or less.

[Measurement method 1]

The total heat release was measured by a cone calorimeter method according to KSF ISO 5660-1 under the conditions of a temperature of 23 캜 and a relative humidity (RH) of 50%.

When the total heat emission amount is high, it means that the flame retardancy is not good, and when the total heat emission amount is low, it means that the flame resistance is excellent.

Further, the flame-retarded foam according to the present invention is characterized in that the time when the total heat release rate measured by the following measurement method 2 continuously exceeds 200 kw / m 2 is 10 seconds or less, preferably 8 seconds or less, more preferably 5 seconds or less , And most preferably less than or equal to one second.

[Measurement method 2]

Under the conditions of a temperature of 23 캜 and a relative humidity (RH) of 50%, the time at which the heat release rate continuously exceeded 200 kW / m 2 by a cone calorimeter method according to KSF ISO 5660-1 was measured.

The fact that the total heat release rate continuously exceeds 200 kw / m 2 means that the flame retardancy is not good, and the fact that the total heat release rate continuously exceeds 200 kw / m 2 is short indicates that the flame retardancy is excellent It can be judged in meaning.

Further, the flame-retarded foam according to the present invention may have an average behavioral stopping time measured by the following Measuring Method 3 of 8 minutes or more, preferably 8.3 minutes or more.

[Measuring method 3]

The average behavior downtime was measured by a gas hazard test method based on KSF 2271 under the conditions of a temperature of 23 ° C and a relative humidity (RH) of 50%.

The fact that the average behavior suspension time is short means that the gas hazard is high and that the average behavior suspension time is long means that the gas hazard is low.

Meanwhile, the flame-retarded foam according to the present invention comprises 65 to 200 parts by weight of starch and 15 to 175 parts by weight of a flame retardant, based on 100 parts by weight of the cellulose-based powder, to prepare a mixture; Pelletizing the mixture; And pelletizing the mixture with 65 to 300 parts by weight of a polymer polymer based on 100 parts by weight of the cellulose-based powder and extrusion foaming the mixture.

In the description of the method for producing a flame-retardant foam to be described later, the same parts as those of the flame-retarded foam described above will be omitted.

According to one embodiment of the present invention, in the pelletizing step, the mixture may be dried to a water content of 10 to 25%, preferably 10 to 20%. If the water content of the mixture is less than 10%, the foaming property and the processability may be deteriorated. If the water content exceeds 25%, extra moisture may be retained in the extruder There is a problem that the binder polymer chain is broken and the shape stability of the foam is not uniform due to unevenness of the melt viscosity of the binder polymer.

Also, according to an embodiment of the present invention, the extrusion foaming step may be carried out through a pressure starting aeration having four to six separate cylinders having a predetermined temperature gradient.

In this case, the temperature of the first cylinder may be 60 to 90 ° C, the temperature of the last cylinder may be 165 to 195 ° C, and each cylinder may be independently controlled to have a temperature gradient of 10 to 50 ° C, Foaming can be performed. If the temperature condition and the temperature difference condition are not satisfied, the foaming property and / or the heat insulating property of the flame retardant foaming agent may be lowered.

According to an embodiment of the present invention, the step of aging may be further included after the extrusion foaming step. The step of aging is a step of cooling the extruded foamed flame-retarded foam and functioning to allow the polymer comprising the modified polyolefin polymer to function as a binder polymer. The aging is not limited as long as the aging time can be generally performed in the art, and thus the aging time is not particularly limited in the present invention.

The flame-retarded foamed product of the present invention and the method of producing the same have an effect of less gas harmfulness, excellent durability, excellent heat-insulating property, eco-friendly property and flame retardancy remarkably excellent.

The present invention will now be described more specifically with reference to the following examples. However, the following examples should not be construed as limiting the scope of the present invention, and should be construed to facilitate understanding of the present invention.

< Example  1>

First, to prepare a mixture, 120 parts by weight of a starch having a water content of 10% with respect to 100 parts by weight of a paper powder having an average particle size of 200 mu m as a cellulose-based powder, 100 parts by weight of polyphenylene sulfide and meta 80 parts by weight of aramid in a weight ratio of 1: 1 were stirred and mixed and pelletized to dry the mixture to a moisture content of 15%.

Thereafter, to the pelletized mixture, 160 parts by weight of a polyolefin polymer modified with a high molecular polymer was added to 100 parts by weight of the cellulose-based powder, and through the pressure starting furnace equipped with five separate compressor cylinders, Extruded at a temperature of 110 캜, a third cylinder at 150 캜, a fourth cylinder at 173 캜 and a fifth cylinder at 180 캜, and aged for 3 hours to prepare a fire retardant foam.

< Example  2 to 18 and Comparative Example  1 to 6>

The same procedure as in Example 1 was carried out except that the average particle size of cellulose powder, the content of starch, the content of polymer polymer, the content of flame retardant, the weight ratio, the average particle diameter and the water content of the mixture in the pelletization step were changed, To prepare flame-retardant foams as shown in Table 4.

< Experimental Example >

The following properties of the flame retarded foam prepared in Examples and Comparative Examples were evaluated and shown in Tables 1 to 4 below.

1. Total Heat emission  Measure

The total heat release was measured by a cone calorimeter method according to KSF ISO 5660-1 under conditions of a temperature of 23 캜 and a relative humidity (RH) of 50% for the flame retarded foam prepared according to Examples and Comparative Examples.

2. The heat release rate  200 kW / ㎡  Continuous over time measurement

The heat release rate of the flame-retarded foam prepared according to the examples and comparative examples was 200 kw / m2 continuously with the cone calorimeter method according to KSF ISO 5660-1 under conditions of a temperature of 23 캜 and a relative humidity (RH) of 50% And the time exceeded was measured.

3. Durability evaluation

The durability of the flame retarded foam prepared according to Examples and Comparative Examples was evaluated by a cone calorimeter method according to KSF ISO 5660-1 at a temperature of 23 캜 and a relative humidity (RH) of 50% - &amp; cir &amp;, a case where any abnormality such as a complete melting of the core material, a crack and a hole penetrating through the core material occurred, - &amp; cir &amp;

4. Gas Hazard Assessment

The average behavioral stopping time of the flame retarded foam prepared according to Examples and Comparative Examples was measured by a gas harmfulness test method based on KSF 2271 under conditions of a temperature of 23 캜 and a relative humidity (RH) of 50%.

5. Evaluation of insulation

For the fire-retardant foam prepared according to Examples and Comparative Examples, the heat conductivity was evaluated by the thermal conductivity evaluation method, the thermal conductivity was measured by ASTM C 518 (Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus), ISO 8301 (Thermal Insulation-Determination of Steady-State Thermal Resistance and Related Properties) and KS L 9016 (Thermal Conductivity Measurement Method). The thermal conductivity was set at 33 ° C on the high temperature side and 7 ° C on the low temperature side in a constant temperature and humidity room controlled at a room temperature of 23 ± 1 ° C and a relative humidity of 50 ± 5%, and the average test temperature was set at 20 ± 0.5 ° C. (T _u , T _i ) on the low temperature side, the passed heat flux (Q _t ) measured by the heat flow meter, and the thickness (d) of the heat insulating material specimen. Measurements were taken 5 times at 10 minute intervals after the temperature and flow rate reached steady state and the mean value was calculated.

6. Fairness Assessment

The flame-retarded foam prepared according to Examples and Comparative Examples were evaluated for their fairness in the case where any abnormality was found in any of the processes of -?, Defective foaming, over-foaming and the like.

division Example
One Example
2 Example
3 Example
4 Example
5 Example
6 Cellulose-based powder Average particle diameter (占 퐉) 200 200 200 200 200 200 Starch Content (parts by weight) 120 80 180 120 120 120 Polyolefin polymer Content (parts by weight) 160 160 160 80 260 160 Flame retardant material Content (parts by weight) 80 80 80 80 80 25 PPS and m-aramid weight ratio 1: 1 1: 1 1: 1 1: 1 1: 1 1: 1 Average particle diameter (占 퐉) 80 80 80 80 80 80 Pelletization step Mixture Moisture Content (%) 15 15 15 15 15 15 Total heat emission measurement (MJ / ㎡) 6.6 6.7 6.7 6.7 6.7 7.3 The time (s) during which the heat release rate continuously exceeds 200 kW / 0 0 0 0 0 0 Durability evaluation ○ ○ ○ ○ ○ ○ Gas Hazard Assessment (average downtime, min) 11.55 11.45 11.35 11.5 11.45 9.2 Heat insulation evaluation
(Thermal conductivity, W / mK) 0.035 0.035 0.037 0.037 0.036 0.035 Fairness evaluation ○ ○ ○ ○ ○ ○

division Example
7 Example
8 Example
9 Example
10 Example
11 Example
12 Cellulose-based powder Average particle diameter (占 퐉) 200 350 600 200 200 200 Starch Content (parts by weight) 120 120 120 120 120 120 Polyolefin polymer Content (parts by weight) 160 160 160 160 160 160 Flame retardant material Content (parts by weight) 160 80 80 80 80 80 PPS and m-aramid weight ratio 1: 1 1: 1 1: 1 1: 0.3 1: 0.7 1: 1.5 Average particle diameter (占 퐉) 80 80 80 80 80 80 Pelletization step Mixture Moisture Content (%) 15 15 15 15 15 15 Total heat emission measurement (MJ / ㎡) 6.3 7.6 8.3 8.5 6.9 6.4 The time (s) during which the heat release rate continuously exceeds 200 kW / 0 0 2 0 0 0 Durability evaluation ○ ○ ○ ○ ○ ○ Gas Hazard Assessment (average downtime, min) 11.65 8.9 7.7 7.4 10.7 11.6 Heat insulation evaluation
(Thermal conductivity, W / mK) 0.037 0.037 0.044 0.037 0.036 0.035 Fairness evaluation ○ ○ ○ ○ ○ ○

division Example
13 Example
14 Example
15 Example
16 Example
17 Example
18 Cellulose-based powder Average particle diameter (占 퐉) 200 200 200 200 200 200 Starch Content (parts by weight) 120 120 120 120 120 120 Polyolefin polymer Content (parts by weight) 160 160 160 160 160 160 Flame retardant material Content (parts by weight) 80 80 80 80 80 80 PPS and m-aramid weight ratio 1: 2.5 1: 1 1: 1 1: 1 1: 1 1: 1 Average particle diameter (占 퐉) 80 100 150 80 80 80 Pelletization step Mixture Moisture Content (%) 15 15 15 5 20 30 Total heat emission measurement (MJ / ㎡) 8.2 6.8 8.6 8.1 6.7 6.9 The time (s) during which the heat release rate continuously exceeds 200 kW / 0 0 One 0 0 0 Durability evaluation ○ ○ ○ ○ ○ ○ Gas Hazard Assessment (average downtime, min) 7.6 10.9 7.5 8.1 11.1 9.2 Heat insulation evaluation
(Thermal conductivity, W / mK) 0.037 0.035 0.036 0.036 0.035 0.037 Fairness evaluation ○ ○ ○ × ○ ×

division Comparative Example
One Comparative Example
2 Comparative Example
3 Comparative Example
4 Comparative Example
5 Comparative Example
6 Cellulose-based powder Average particle diameter (占 퐉) 200 200 200 200 200 200 Starch Content (parts by weight) 50 230 120 120 120 120 Polyolefin polymer Content (parts by weight) 160 160 50 350 160 160 Flame retardant material Content (parts by weight) 80 80 80 80 5 200 PPS and m-aramid weight ratio 1: 1 1: 1 1: 1 1: 1 1: 1 1: 1 Average particle diameter (占 퐉) 80 80 80 80 80 80 Pelletization step Mixture Moisture Content (%) 15 15 15 15 15 15 Total heat emission measurement (MJ / ㎡) 6.9 7.0 6.8 6.8 10.9 5.4 The time (s) during which the heat release rate continuously exceeds 200 kW / 0 0 0 0 13 0 Durability evaluation × ○ × ○ × ○ Gas Hazard Assessment (average downtime, min) 10 10.3 11.15 10.7 6.3 11.22 Heat insulation evaluation
(Thermal conductivity, W / mK) 0.036 0.049 0.046 0.042 0.036 0.049 Fairness evaluation × × × × ○ ×

As can be seen from Tables 1 to 4 above,

Examples 1 to 8, 11, and 12, which satisfied all of the average particle size, starch content, polyolefin polymer content, flame retardant content, weight ratio, average particle diameter and water content of the mixture in the pelletization step, 12, 14 and 17 are lower than those of Examples 9, 10, 13, 15, 16, 18 and Comparative Examples 1 to 6 in which any one of them is omitted and the heat release rate is continuously exceeding 200 kw / It was short in one hour (s), excellent in durability, excellent in flame retardancy, low in gas harmfulness, and excellent in processability.

Specifically, Example 1 and Example 8 satisfying the average particle diameter range of the cellulose-based powder according to the present invention had a lower total heat emission amount and a heat release rate of 200 kw / The time exceeded was short, gas toxicity was low, and insulation was excellent.

In addition, Examples 1, 11, and 12 satisfying the weight ratio of the flame retardant according to the present invention had lower total heat emission and less gas toxicity than Examples 10 and 13, which did not satisfy the requirements.

Further, Examples 1 and 14, which satisfy the average particle size range of the flame retardant material according to the present invention, have a lower total heat emission amount than the Example 15 in which the heat release rate is less than 200 kw / Time was short and gas hazard was low.

Further, Examples 1 and 17, which satisfied the water content range of the mixture in the pelletization step according to the present invention, had lower total heat emission, less gas harmfulness, and superior processability than Example 16, , The gas harmfulness was less than that of Example 18, and the processability was excellent.

In addition, Examples 1 to 3 satisfying the content range of starch according to the present invention were superior in durability and processability to Comparative Example 1 which did not satisfy the requirements, and were superior in heat insulation and fairness to Comparative Example 2.

In addition, Examples 1, 4 and 5 satisfying the content range of the polyolefin polymer according to the present invention were superior in durability, heat insulation and fairness to Comparative Example 3 which did not satisfy the content range, Insulation and fairness.

In Example 1, Example 6 and Example 7, which satisfy the content range of the flame retardant according to the present invention, the total heat emission amount is low and the heat release rate is 200 kw / The time exceeded was remarkably short, the durability was excellent, and the gas harmfulness was low. In addition, the heat insulating property and the processability were superior to those of Comparative Example 6.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, 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 (15)

65 to 300 parts by weight of a starch, 65 to 300 parts by weight of a polymer, and a mixture of polyphenylene sulfide (PPS) and meta-aramid (m-Aramid) in a weight ratio of 1: 0.5 to 2 based on 100 parts by weight of the cellulose- And 15 to 175 parts by weight of a flame retardant substance having an average particle diameter of 120 탆 or less,
Wherein the mixture containing cellulose-based powder, starch and flame retardant is pelletized so as to have a moisture content of 10 to 25%, and then treated with the polymer to be extruded and foamed. The method according to claim 1,
Wherein the cellulose-based powder comprises paper powder. The method according to claim 1,
Wherein said cellulose-based powder has an average particle size of 500 mu m or less. The method according to claim 1,
Wherein the starch is a moisture content of 20% or less. The method according to claim 1,
Wherein the polymer comprises at least one member selected from the group consisting of polyolefin, polyamide, polyester, acrylonitrile butadiene styrene, and polylactic acid. delete delete delete The method according to claim 1,
Wherein a total heat release amount measured by the following Measuring Method 1 is 8 MJ / m &lt; 2 &gt; or less.
[Measurement method 1]
The total heat release was measured by a cone calorimeter method according to KSF ISO 5660-1 under the conditions of a temperature of 23 캜 and a relative humidity (RH) of 50%. The method according to claim 1,
Wherein the time when the heat release rate measured by the following measurement method 2 continuously exceeds 200 kw / m &lt; 2 &gt; is 10 seconds or less.
[Measurement method 2]
Under the conditions of a temperature of 23 캜 and a relative humidity (RH) of 50%, the time at which the heat release rate continuously exceeded 200 kW / m 2 by a cone calorimeter method according to KSF ISO 5660-1 was measured. The method according to claim 1,
Wherein the average behavior stopping time measured by the following Measuring Method 3 is 8 minutes or more.
[Measuring method 3]
The average behavior downtime was measured by a gas hazard test method based on KSF 2271 under the conditions of a temperature of 23 ° C and a relative humidity (RH) of 50%. (A), wherein 65 to 200 parts by weight of starch and 100 to 200 parts by weight of polyphenylene sulfide (PPS) and meta-aramid (m-Aramid) are contained at a weight ratio of 1: 0.5 to 2 based on 100 parts by weight of the cellulose- Mixing 15 to 175 parts by weight of a flame retardant material to prepare a mixture;
Pelletizing the mixture to a water content of 10 to 25%; And
Treating the blended mixture with 65 to 300 parts by weight of a polymer polymer based on 100 parts by weight of the cellulose-based powder, and extrusion foaming the resultant mixture. delete 13. The method of claim 12,
Wherein the extrusion foaming step is performed through a pressure starting furnace having 4 to 6 separate cylinders having a predetermined temperature gradient. 13. The method of claim 12,
And aging the extruded foamed product after the extrusion foaming step.