JP2012172140A - Styrenic resin extruded foam and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a styrenic resin extruded foam which has excellent flame retardancy and thermal stability.SOLUTION: The styrenic resin extruded foam is obtained by performing extrusion foaming using a styrenic resin and a foaming agent. By including a bromine-based flame retardant in 1 to 6 pts.wt. to 100 pts.wt. of the styrenic resin, and also including polyhydric alcohol in 1 to 50 pts.wt. to 100 pts.wt. of the bromine-based flame retardant, the styrenic resin extruded foam having the above characteristics can be obtained.

Description

  The present invention relates to a styrenic resin foam having both thermal stability and flame retardancy, and a method for producing the same.

  A method for continuously producing a styrene resin foam by melting a styrene resin with an extruder or the like, then adding a foaming agent, cooling it, and extruding it into a low pressure region is already known. ing.

In order to satisfy the flammability standard of the extruded styrene foam heat insulating plate described in JIS A9511, a flame retardant is added to the styrene resin foam.
The main necessary characteristics of the flame retardant suitable for the styrene resin extruded foam are around a general polystyrene extrusion condition of 230 ° C., and it is required that the flame retardant does not decompose near this temperature. When the flame retardant decomposes under the extrusion conditions, the resin is deteriorated and adverse effects such as deterioration of moldability of the obtained foam, deterioration of flame retardancy, or difficulty in controlling the foam cell diameter are obtained.

  Another necessary characteristic of the flame retardant suitable for the styrene resin extruded foam is that the flame retardant decomposes efficiently before the decomposition of polystyrene. Polystyrene is known to decompose from around 300 ° C. If the flame retardant is not efficiently decomposed at a temperature lower than the decomposition temperature of polystyrene, the flammability standard described in JIS A9511 may not be satisfied. Alternatively, in order to obtain the necessary flame retardancy, the number of added flame retardants must be increased as a result, which tends to have adverse effects such as an increase in product cost and deterioration of moldability of the resulting foam.

From the above background, hexabromocyclododecane (hereinafter abbreviated as HBCD) has been widely used as a flame retardant for styrene resin extruded foams. HBCD is known to be relatively stable under extrusion conditions and to be efficiently decomposed when polystyrene is decomposed, and can exhibit high flame retardancy with a small number of added parts.
On the other hand, HBCD is a compound that is hardly degradable and highly accumulative for ecology, so it is not preferable in terms of environmental hygiene, and it is desired to reduce the amount of HBCD used and to develop a flame retardant that replaces HBCD.

Then, examination of the styrene resin extrusion foam using brominated flame retardants other than HBCD is made.
By the way, brominated flame retardants are large and can be classified into two types.
One is an aromatic brominated flame retardant in which bromine is added only to the aromatic ring, which has a high decomposition temperature and is relatively easy to extrude, but tends to have a low flame retardant performance. The performance required for the resin foam tends to be difficult to obtain (for example, Patent Document 1).
As another brominated flame retardant, there is an aliphatic brominated flame retardant in which bromine is added to an aliphatic site. This provides relatively high flame retardancy, but tends to be unstable under the extrusion conditions, and may cause problems such as resin degradation (for example, Patent Document 2).

  Based on the above background, studies have been made on additives that increase the thermal stability of brominated flame retardants and additives that increase the flame retardancy performance of brominated flame retardants. Flame retardant technology still leaves room for improvement.

JP 2005-54004 A JP 2006-316251 A

  The present invention has been made in order to solve the above-mentioned problems of the flame retardant styrene resin extruded foam, and has a styrene resin extruded foam excellent in thermal stability and flame retardancy, and a method for producing the same. The purpose is to provide.

  As a result of diligent research to solve the above problems, the present inventors have obtained a styrene resin foam obtained by melting and kneading a styrene resin and a foaming agent in an extruder and extruding and foaming under a low pressure region. 1 to 6 parts by weight of brominated flame retardant with respect to 100 parts by weight of resin, and 1 to 50 parts by weight of polyhydric alcohol stabilizer with respect to 100 parts by weight of brominated flame retardant. Thus, a styrene resin extruded foam having the above characteristics can be obtained.

That is, the present invention
[1] A styrene resin foam obtained by extrusion foaming using a styrene resin and a foaming agent,
1-6 parts by weight of brominated flame retardant with respect to 100 parts by weight of styrene resin, and
1 to 50 parts by weight of a polyhydric alcohol stabilizer based on 100 parts by weight of the brominated flame retardant, a styrene resin extruded foam,
[2] The styrenic resin extruded foam according to [1], wherein the brominated flame retardant is an aliphatic brominated flame retardant in which bromine is also added to an aliphatic alkyl moiety.
[3] The brominated flame retardant is hexabromocyclododecane, tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether, tetrabromobisphenol A-bis (2,3-dibromopropyl) ether, The styrenic resin extruded foam according to [1] or [2], which is at least one selected from tris (2,3-dibromopropyl) isocyanurate and chloropentabromocyclohexane,
[4] The styrenic resin extruded foam according to any one of [1] to [3], wherein the foaming agent comprises at least one selected from saturated hydrocarbons having 3 to 5 carbon atoms. body,
[5] The foaming agent further contains at least one selected from the group consisting of water, carbon dioxide, nitrogen, alcohols having 2 to 5 carbon atoms, dimethyl ether, methyl chloride, and ethyl chloride as another foaming agent. The styrene resin extruded foam according to [4], characterized by:
[6] The styrene resin extruded foam according to [4] or [5], wherein the other foaming agent contains water,
[7] The styrenic system according to [6], wherein the bubble diameter forming the foam is mainly composed of bubbles having a bubble diameter of 0.2 mm or less and bubbles having a bubble diameter of 0.25 to 1 mm. Resin extruded foam,
[8] The occupying area ratio per foam cross-sectional area of bubbles having a bubble diameter of 0.2 mm or less among the bubbles forming the foam is 5 to 95%. A method for producing a styrene resin foam obtained by extrusion foaming using a styrene resin and [9] styrene resin and a foaming agent,
1 to 6 parts by weight of a brominated flame retardant with respect to 100 parts by weight of styrene resin, and
The present invention relates to a method for producing a styrene resin extruded foam, comprising 1 to 50 parts by weight of a polyhydric alcohol stabilizer based on 100 parts by weight of the brominated flame retardant.

  The styrene resin extruded foam of the present invention is a styrene resin foam obtained by extrusion foaming using a styrene resin and a foaming agent, wherein the brominated flame retardant is added to 100 parts by weight of the styrene resin. Styrene containing 1 to 6 parts by weight and containing a polyhydric alcohol stabilizer in an amount of 1 to 50 parts by weight with respect to 100 parts by weight of the brominated flame retardant. It is a resin-based extruded foam.

  The styrene resin foam of the present invention is a styrene resin foam obtained by extrusion foaming using a styrene resin, a bromine flame retardant, a polyhydric alcohol stabilizer and a foaming agent.

  The styrenic resin used in the present invention is not particularly limited, and is obtained from a styrene homopolymer obtained only from a styrene monomer; a monomer copolymerizable with styrene monomer and styrene, or a derivative thereof. Examples thereof include random, block or graft copolymers; post-brominated styrene, modified styrene such as rubber-reinforced styrene, and the like. These can be used alone or in admixture of two or more.

  Examples of monomers copolymerizable with styrene include styrene derivatives such as methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, bromostyrene, dibromostyrene, tribromostyrene, chlorostyrene, dichlorostyrene, and trichlorostyrene; Polyfunctional vinyl compounds such as divinylbenzene; (meth) acrylic compounds such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, acrylonitrile; diene compounds such as budadiene or Derivatives thereof; unsaturated carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride. These can be used alone or in admixture of two or more.

  Among the styrene resins, styrene homopolymers, styrene acrylonitrile copolymers, (meth) acrylic acid copolymer styrenes, maleic anhydride-modified styrenes, impact styrenes, and the like are preferable from the viewpoint of extrusion foam moldability and the like. Particularly preferred is a styrene homopolymer from the viewpoint of cost.

  In this invention, a flame retardance can be provided to the styrene resin foam obtained by containing a brominated flame retardant as a flame retardant.

Specific examples of bromine compounds include brominated alicyclic compounds such as hexabromocyclododecane, tetrabromocyclooctane, and chloropentabromocyclohexane; hexabromobenzene, pentabromotoluene, ethylenebispentabromodiphenyl, decabromodiphenyl ether, Bromination of 2,3-dibromopropylpentabromophenyl ether, bis (2,4,6-tribromophenoxy) ethane, tetrabromophthalic anhydride, octabromotrimethylphenylindane, pentabromobenzyl acrylate, tribromophenyl allyl ether, etc. Aromatic compounds or derivatives thereof: tetrabromobisphenol-A, tetrabromobisphenol-S, tetrabromobisphenol-F, tetrabromobisphenol-A-bis ( , 3-dibromopropyl ether), tetrabromobisphenol-S-bis (2,3-dibromopropyl ether), tetrabromobisphenol-F-bis (2,3-dibromopropyl ether), tetrabromobisphenol-A-bis ( 2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-S-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-F-bis (2,3-dibromo-2-) Methyl propyl ether), brominated bisphenols such as tetrabromobisphenol-A-diallyl ether, tetrabromobisphenol-S-diallyl ether, tetrabromobisphenol-F-diallyl ether, and derivatives thereof.
These substances may be used alone or as a mixture of two or more.

  Among these, an aliphatic brominated flame retardant in which bromine is added to an aliphatic alkyl moiety is preferably used in that a high flame retardancy can be imparted to the foam with a relatively small number of added parts. . Specifically, hexabromocyclododecane, tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether, tetrabromobisphenol A-bis (2,3-dibromopropyl) ether, tris (2, 3-Dibromopropyl) isocyanurate, chloropentabromocyclohexane and the like are desirably used for the reason that high flame retardancy is easily obtained.

The content of the brominated flame retardant in the styrene resin extruded foam of the present invention can obtain the combustibility specified in JIS A9511 and maintain the thermal stability of the styrene resin in the extruder during foam production. As appropriate, it can be appropriately adjusted according to the type of brominated flame retardant, the amount of foaming agent added, the density of the foam, and, in some cases, the type or amount of other additives. 1 to 6 parts by weight is preferable with respect to 100 parts by weight, and 2 to 5 parts by weight is more preferable.
If the content of brominated flame retardant is less than 1 part by weight, good properties as a foam such as flame retardancy tend to be difficult to obtain. If it exceeds 6 parts by weight, stability during foam production In some cases, surface properties may be impaired.

  In the present invention, by using a polyhydric alcohol stabilizer together with a brominated flame retardant, the thermal stability can be improved without impairing the flame retardant performance of the flame retardant.

The polyhydric alcohol stabilizer used in the present invention is a polyhydric alcohol containing at least one kind of pentaerythritol, dipentaerythritol, tripentaerythritol, or the like, or monovalent such as the polyhydric alcohol and acetic acid, propionic acid, etc. Any carboxylic acid, adipic acid, glutamic acid or other divalent carboxylic acid may be used as long as it is a compound having one or more hydroxyl groups in the molecule.
In this case, the polyhydric alcohol stabilizer may be a polyhydric alcohol or a partial ester of a polyhydric alcohol and an organic acid, or may be a mixture thereof.

  A specific polyhydric alcohol stabilizer is a mixture of a partial ester of dipentaerythritol and adipic acid and a polyhydric alcohol, and the polyhydric alcohol content in the mixture is 10 to 80% by weight. Mixtures (for example, Ajinomoto Fine Techno Co., Ltd., Pleniser ST-210, Plenizer L-ST-220, etc.) can be mentioned.

The compounding quantity of the polyhydric alcohol stabilizer in this invention is 1-50 weight part with respect to 100 weight part of brominated flame retardants, and 1-25 weight part is preferable.
When the blending amount of the polyhydric alcohol stabilizer is less than 1 part by weight, the thermal stabilization effect tends to be small. On the other hand, when the blending amount of the polyhydric alcohol stabilizer exceeds 50 parts by weight, the stabilization effect is greatly exerted, and the flame retardancy performance of the flame retardant itself may be lowered.

  Although it does not specifically limit as a foaming agent used by this invention, The outstanding environmental compatibility can be provided by using at least 1 sort (s) chosen from a C3-C5 saturated hydrocarbon. .

  Examples of the saturated hydrocarbon having 3 to 5 carbon atoms used in the present invention include propane, n-butane, i-butane, n-pentane, i-pentane, neopentane and the like. Among these saturated hydrocarbons having 3 to 5 carbon atoms, propane, n-butane, i-butane, or a mixture thereof is preferable from the viewpoint of foamability. Moreover, n-butane, i-butane, or a mixture thereof is preferable from the viewpoint of the heat insulating performance of the foam, and i-butane is particularly preferable.

  In the present invention, by using another foaming agent, a plasticizing effect and an auxiliary foaming effect at the time of foam production can be obtained, the extrusion pressure can be reduced, and the foam can be stably produced. However, depending on various properties of the foam, such as the desired foaming ratio and flame retardancy, the amount used may be limited, and the extrusion foam moldability may not be sufficient.

  Other foaming agents include, for example, ethers such as dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisopropyl ether, furan, furfural, 2-methyl furan, tetrahydrofuran, tetrahydropyran; dimethyl ketone, methyl ethyl ketone , Diethyl ketone, methyl n-propyl ketone, methyl-n-butyl ketone, methyl-i-butyl ketone, methyl-n-amyl ketone, methyl-n-hexyl ketone, ethyl-n-propyl ketone, ethyl-n-butyl ketone, etc. A saturated alcohol having 1 to 4 carbon atoms such as methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, t-butyl alcohol; Organic esters such as acid methyl ester, formic acid ethyl ester, formic acid propyl ester, formic acid butyl ester, formic acid amyl ester, propionic acid methyl ester, propionic acid ethyl ester; alkyl halides such as methyl chloride and ethyl chloride A foaming agent, an inorganic foaming agent such as water or carbon dioxide, a chemical foaming agent such as an azo compound or tetrazole, or the like can be used. These other blowing agents may be used alone or in combination of two or more.

  Among other foaming agents, from the viewpoints of foamability, foam formability, etc., saturated alcohols having 1 to 4 carbon atoms, dimethyl ether, diethyl ether, methyl ethyl ether, methyl chloride, ethyl chloride, etc. are preferable. From the viewpoints of the flammability of the foam, the flame retardancy of the foam, the heat insulation properties described later, and the like, water and carbon dioxide are preferred. Among these, dimethyl ether is particularly preferable from the viewpoint of the plasticizing effect, and water is particularly preferable from the viewpoint of the effect of improving the heat insulation by controlling the cost and the bubble diameter.

  The pressure when adding or injecting the foaming agent in the present invention is not particularly limited as long as it is higher than the internal pressure of an extruder or the like.

  The amount of the foaming agent used in the present invention is preferably 2 to 20 parts by weight and more preferably 2 to 10 parts by weight with respect to 100 parts by weight of the styrene resin. When the addition amount of the foaming agent is less than 2 parts by weight, the foaming ratio is low, and the characteristics such as light weight and heat insulation as the resin foam may be difficult to be exhibited. Therefore, defects such as voids may occur in the foam.

  In the present invention, by using water as the other foaming agent, in the styrene-based resin extruded foam, bubbles having a relatively small bubble diameter of approximately 0.2 mm or less (hereinafter referred to as small bubbles), A foam having a characteristic bubble structure in which bubbles having a relatively large bubble diameter (hereinafter referred to as large bubbles) having a bubble diameter of about 0.25 mm to 1 mm are mixed in a sea-island shape is obtained, and the foam obtained The heat insulation performance can be improved.

  In a foam having a specific bubble structure in which small bubbles having a bubble diameter of 0.2 mm or less and large bubbles having a bubble diameter of 0.25 to 1 mm are mixed, the ratio of the area of the small bubbles to the cross-sectional area of the foam (small 5 to 95% is preferable, 10 to 90% is more preferable, 20 to 80% is further preferable, and 25 to 70% is preferable. Is particularly preferred.

  In the present invention, when water is used as another foaming agent, it is preferable to add a water-absorbing substance in order to stably perform extrusion foam molding.

  Specific examples of the water-absorbing substance used in the present invention include polyacrylate polymer, starch-acrylic acid graft copolymer, polyvinyl alcohol polymer, vinyl alcohol-acrylate copolymer, ethylene- In addition to water-absorbing polymers such as vinyl alcohol copolymers, acrylonitrile-methyl methacrylate-butadiene copolymers, polyethylene oxide copolymers and derivatives thereof, anhydrous silica (silicon oxide) having silanol groups on the surface [For example, AEROSIL manufactured by Nippon Aerosil Co., Ltd. is commercially available] Fine particle having a hydroxyl group on the surface and having a particle diameter of 1000 nm or less; Water-absorbing or water-swelling layered material such as smectite, swellable fluorine mica Silicates and their organic treated products: zeolite, activated carbon, alumina, silica Gel, porous glass, activated clay, porous material or the like, such as diatomaceous earth and the like.

  The addition amount of the water-absorbing substance used in the present invention is appropriately adjusted depending on the addition amount of water and the like, but is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the styrene resin. 0.1 to 3 parts by weight is more preferable.

  In the present invention, if necessary, further, a phenolic antioxidant, a phosphorus stabilizer, a nitrogenous stabilizer, a sulfur stabilizer, a lactone stabilizer, a benzotriazole stabilizer, a hindered amine stabilizer, etc. Can be contained.

  In the present invention, if necessary, as long as the effects of the present invention are not impaired, processing aids such as fatty acid amides, fatty acid esters, liquid paraffin, olefin waxes, flame retardants other than the above, antistatic agents, Additives such as colorants such as pigments can be included.

  As a method for producing a styrene resin extruded foam of the present invention, a styrene resin, a brominated flame retardant, a polyhydric alcohol additive, and other additives are supplied to a heating and melting means such as an extruder and heated and melted. At any stage in the means, a foaming agent is added to the styrenic resin under high pressure conditions to form a fluid gel, cooled to a temperature suitable for extrusion foaming, and then the fluid gel is extruded and foamed into a low pressure region through a die. Thus, it is manufactured by forming a foam.

  Styrenic resin, brominated flame retardant, polyhydric alcohol stabilizer, and other additives are heated and melted in the form of styrene resin mixed with brominated flame retardant, polyhydric alcohol stabilizer and other additives. Then, heat-melt the styrenic resin, and then add and mix brominated flame retardant, polyhydric alcohol stabilizer, and other additives; brominated flame retardant, stabilizer, and other in advance to the styrene resin After the additives are mixed, a heated and melted composition is prepared, and is supplied again to the extruder and heated and melted.

There are no particular limitations on the heating temperature, melt kneading time, and melt kneading means when the styrene resin and additives such as a foaming agent are heated and melt kneaded.
The heating temperature only needs to be equal to or higher than the temperature at which the styrene resin to be used is melted, but preferably includes a temperature at which molecular degradation of the resin is suppressed as much as possible, for example, about 200 to 250 ° C.
The melt-kneading time varies depending on the amount of extrusion per unit time, the melt-kneading means, etc., and thus cannot be determined unconditionally. However, the time required for uniformly dispersing and mixing the styrene resin and the foaming agent is appropriately selected.
Examples of the melt-kneading means include a screw-type extruder, but there is no particular limitation as long as it is used for ordinary extrusion foaming. However, in order to suppress the molecular degradation of the resin as much as possible, it is preferable to use a low shear type screw for the screw shape.

  The foam molding method is not particularly limited, for example, using a molding die and a molding roll in which a foam obtained by releasing pressure from a slit die is placed in close contact with or in contact with the slit die, a plate shape having a large cross-sectional area A general method for forming a foam can be used.

  The thickness of the styrene resin extruded foam of the present invention is not particularly limited and is appropriately selected depending on the application. For example, in the case of a heat insulating material used for applications such as building materials, in order to give preferable heat insulating properties, bending strength and compressive strength, those having a thickness like a normal plate-like material are preferable, usually 10 to 10 150 mm, preferably 20-100 mm.

The density of the styrene resin extruded foam of the present invention is preferably 15 to 50 kg / m ³ in order to give light weight and excellent heat insulation, bending strength and compressive strength, and preferably 25 to 40 kg / m ^3. m and even more preferably ^3.

  The styrene resin extruded foam of the present invention is suitably used as a heat insulating material for building materials from the viewpoint of excellent thermal stability, flame retardancy and heat insulating performance.

  Next, although the manufacturing method of the thermoplastic resin extrusion foam of this invention is demonstrated still in detail based on an Example, this invention is not restrict | limited only to this Example.

The raw materials used in the examples and comparative examples are as follows.
(A) Styrenic resin / virgin polystyrene [manufactured by PS Japan, G9401]
(B) Brominated flame retardant hexabromocyclododecane [manufactured by Albemarle, HP900]
Tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether [Daiichi Kogyo Seiyaku Co., Ltd., Pyroguard SR-130]
Tetrabromobisphenol A-bis (2,3-dibromopropyl) ether [Daiichi Kogyo Seiyaku Co., Ltd., Pyroguard SR-720]
(C) Polyhydric alcohol stabilizer / Planelizer ST-210 [Ajinomoto Fine Techno Co., Ltd.]
(D) Foaming agent / isobutane [Mitsui Chemicals, Inc.]
・ Normal butane [Made by Iwatani Corporation]
・ Water [tap water]
・ Dimethyl ether [Mitsui Chemicals, Inc.]
・ Carbon dioxide [made by Iwatani Corporation]
(E) Other additives
・ Talc [manufactured by Hayashi Kasei Co., Ltd., Talcan powder PK-Z]
Bentonite [Wilver Ellis, Gel White H]
・ Aerosil [Nippon Aerosil Co., Ltd., AEROSIL]

  The evaluation methods implemented in the examples and comparative examples are as follows.

(1) Foam density The foam density is determined based on foam density [g / cm ³ ] = foam weight [g] / foam volume [cm ³ ], and the unit is converted to [kg / m ³ ]. Showed.

(2) Small bubble area ratio About the extrusion foam, the occupied area ratio per foam foam cross-sectional area of the bubble diameter of 0.2 mm or less was calculated | required as follows. Here, the bubble having a bubble diameter of 0.2 mm or less means a bubble having an equivalent circle diameter of 0.2 mm or less.
a) A vertical section of the foam magnified 30 times is photographed with a scanning electron microscope [manufactured by Hitachi, Ltd., product number: S-450].
b) An OHP sheet is placed on the photograph taken, and a portion corresponding to a bubble having a diameter in the thickness direction larger than 6.0 mm (corresponding to a bubble having an actual dimension larger than 0.2 mm) is black ink. Fill in and copy (primary processing).
c) The primary processing image is taken into the image processing apparatus [Pierce Co., Ltd., product number: PIAS-II], and the dark color portion and the light color portion, that is, the portion painted with black ink are identified.
d) A portion corresponding to the area of a circle having a diameter of 6.0 mm or less in the dark colored portion (that is, a portion having a long diameter in the thickness direction but only having an area of a circle having a diameter of 6.0 mm or less). ) Is lightened to correct the dark portion.
e) Using “FRACTAREA (area ratio)” in the image analysis calculation function, the area ratio of the bubble diameter of 6.0 mm or less (light color portion divided by shading) in the entire image is obtained by the following equation.
Small bubble occupation area ratio [%] = (1−area of dark color portion / area of entire image) × 100

(3) Flammability
In accordance with JIS A9511, a test piece having a thickness of 10 mm, a length of 200 mm, and a width of 25 mm was used, and evaluation was performed according to the following criteria. The measurement was performed on the foam after 7 days after being cut into the above-mentioned dimensions after production.
Burning time
A: All 5 flame extinguishing times are within 3 seconds
○: Among 5 flame extinguishing times, at least one exceeds 3 seconds, but the remaining 3 or more are within 3 seconds
△: At least 3 out of 5 flame extinguishing times exceed 3 seconds, but the remaining one or more are within 3 seconds
×: All 5 flame extinguishing times exceed 3 seconds
Burning distance
◎: Stops within the limit line with all five
○: At least 1 out of 5 decreases over the limit line, but the remaining 3 or more stop burning within the limit line
Δ: At least 3 out of 5 burns exceed the limit line, but the remaining one or more stop within the limit line
×: Combustion exceeds the limit line with all five
Combustion status
A: No burning of foaming agent is observed
○: Some burning of the blowing agent is observed
Δ: Foaming agent burning is seen, but not completely burned
X: Burning of foaming agent is also observed and burns

(4) η _sp
The relative viscosity η _sp of the extruded foam is measured by the following method.
About 1 g of the obtained extruded foam is dissolved in about 30 mL of methyl ethyl ketone in a test tube with a stopper, and the test tube is stoppered and allowed to stand for 6 hours or more. After standing, the supernatant in the test tube is taken out into a beaker, ethanol is added to reprecipitate the resin, and the solvent is completely evaporated in an oven at 70 ° C.
250 mg of the obtained resin content is dissolved in 25 mL of toluene, and the relative viscosity with respect to toluene at 30 ° C. is measured with respect to 10 mL of the obtained toluene solution using an Ubbelohde viscosity tube.
The relative viscosity η _sp is calculated by the following formula.
η _sp = {(passage time of resin toluene solution) / (passage time of toluene)} − 1

(5) Thermal conductivity The thermal conductivity was measured according to JIS A9511. The measurement was performed on a foam after 30 days from the production of the foam.

Example 1
To 100 parts of styrene resin, 4.0 parts of tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether as a brominated flame retardant and 0.02 of the riser ST210 as a polyhydric alcohol stabilizer. A resin mixture comprising 1 part, 0.5 part talc, 1.0 part bentonite and 0.1 part Aerosil was dry blended.
About 50 kg / hr of the obtained resin mixture to a tandem type two-stage extruder in which a single screw extruder (first extruder) having a diameter of 65 mm and a single screw extruder (first extruder) having a diameter of 90 mm are connected in series. Was supplied at a rate of
The resin mixture supplied to the first extruder was melted or plasticized and kneaded by heating to a resin temperature of 200 ° C., and the foaming agent shown below was press-fitted into the resin near the tip of the first extruder. Thereafter, in the second extruder connected to the first extruder, the resin temperature is cooled to 120 ° C., and the atmosphere of the rectangular cross-section die having a thickness of 2 mm × width of 50 mm provided at the tip of the second extruder. After extrusion foaming, an extruded foam plate having a cross-sectional shape of 50 mm in thickness and 150 mm in width was obtained with a molding die placed in close contact with the die and a molding roll installed on the downstream side thereof.
In addition, as a foaming agent, 0.7 weight part of water, 4 weight part of isobutane, and 2 weight part of dimethyl ether were used with respect to 100 weight part of styrene resin.
The properties of the obtained foam are shown in Table 1.

(Examples 2 to 6)
As shown in Table 1, with the same operation as in Example 1, except that the type and amount of foaming agent, the type and amount of flame retardant, and the type and amount of other compounding agents were changed, Obtained.
The properties of the obtained foam are shown in Table 1.

(Comparative Examples 1-3)
As shown in Table 1, with the same operation as in Example 1, except that the type and amount of foaming agent, the type and amount of flame retardant, and the type and amount of other compounding agents were changed, Obtained. The properties of the obtained foam are shown in Table 2.

As is clear by comparing Examples 1 to 5 and Comparative Examples 1 to 3, the polyhydric alcohol stabilizer contains 1 to 6 parts by weight of a brominated flame retardant with respect to 100 parts by weight of the styrene resin. Is contained in an amount of 1 part by weight to 50 parts by weight with respect to 100 parts by weight of the brominated flame retardant, thereby stably obtaining an extruded foam having improved thermal stability while maintaining high flame retardancy. You can see that

Claims (9)

A styrene resin foam obtained by extrusion foaming using a styrene resin and a foaming agent,
1 to 6 parts by weight of a brominated flame retardant with respect to 100 parts by weight of styrene resin, and
1 to 50 parts by weight of a polyhydric alcohol stabilizer based on 100 parts by weight of the brominated flame retardant.   The styrenic resin extruded foam according to claim 1, wherein the brominated flame retardant is an aliphatic brominated flame retardant in which bromine is also added to an aliphatic alkyl site.   Brominated flame retardants include hexabromocyclododecane, tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether, tetrabromobisphenol A-bis (2,3-dibromopropyl) ether, tris (2 3, 3-dibromopropyl) isocyanurate and chloropentabromocyclohexane, at least one selected from styrene-based resin extruded foams according to claim 1 or 2.   The styrene resin extruded foam according to any one of claims 1 to 3, wherein the foaming agent comprises at least one selected from saturated hydrocarbons having 3 to 5 carbon atoms.   The foaming agent further includes at least one selected from the group consisting of water, carbon dioxide, nitrogen, alcohols having 2 to 5 carbon atoms, dimethyl ether, methyl chloride, and ethyl chloride as another foaming agent. The styrene resin extruded foam according to claim 4.   The styrene resin extruded foam according to claim 4 or 5, wherein the other foaming agent contains water.   The styrene-based resin extruded foam according to claim 6, wherein the bubble diameter forming the foam is mainly composed of bubbles having a bubble diameter of 0.2 mm or less and bubbles having a bubble diameter of 0.25 to 1 mm. body.   8. The styrene resin according to claim 7, wherein an occupied area ratio per cross-sectional area of a foam having a bubble diameter of 0.2 mm or less among bubbles forming the foam is 5 to 95%. Extruded foam. A method for producing a styrene resin foam obtained by extrusion foaming using a styrene resin and a foaming agent,
1 to 6 parts by weight of a brominated flame retardant with respect to 100 parts by weight of styrene resin, and
A method for producing an extruded foam of a styrene resin, comprising 1 to 50 parts by weight of a polyhydric alcohol stabilizer relative to 100 parts by weight of the brominated flame retardant.