JP2012136674A - Styrene-based resin extrusion foam body, and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a styrene-based resin extrusion foam body excellent in non-combustibility, heat insulating property and thermal stability.SOLUTION: The styrene-based resin extrusion foam body is obtained by heating and melting a styrene-based resin, and adding a foaming agent thereto followed by extrusion foaming. The foam body contains, based on 100 pts.wt. of the styrene-based resin, 1-6 pts.wt. of a mixed bromine-based flame retarder, and 0.5-6 pts.wt. of at least one boric acid-containing compound selected from boric hydrate, boric acid, barium borate, magnesium borate, and potassium borate. The mixed bromine-based flame retarder is composed of (A) tetrabromobisphenol-A-bis(2,3-dibromo-2-methylpropylether) and tetrabromobisphenol-A-bis(2,3-dibromopropylether), or of (B) tetrabromobisphenol-A-bis(2,3-dibromo-2-methylpropylether) and tris (2,3-dibromopropyl)isocyanurate, and the content of tetrabromobisphenol-A-bis(2,3-dibromo-2-methylpropylether) is 25-75 wt.% relative to 100 wt.% of the entire mixed bromine-based flame retarder.

Description

  The present invention relates to a styrene resin foam excellent in flame retardancy and excellent in heat insulation and thermal stability, 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 required characteristic of a flame retardant suitable for a styrene resin extruded foam is that the flame retardant does not decompose at a temperature around 230 ° C., which is a general styrene resin extrusion condition. When the flame retardant decomposes under the extrusion process conditions, the resin is deteriorated, and thus the obtained foam has adverse effects such as deterioration of moldability and difficulty in controlling the foam cell diameter.
Another necessary characteristic of the flame retardant suitable for the styrene resin extruded foam is that the flame retardant decomposes efficiently before the styrene resin is decomposed. Polystyrene is known to decompose from around 300 ° C. Therefore, if the flame retardant is not efficiently decomposed at a temperature lower than around 300 ° C., there is a possibility that the flammability standard described in JIS A9511 is not 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.

  In recent years, tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) has been proposed as a flame retardant instead of HBCD.

  Tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) has a flame retardancy of almost the same level as HBCD, but has a problem in thermal stability and requires the addition of a stabilizer. Become. On the other hand, as shown in Patent Document 1, a technique is disclosed in which thermal stability is improved by using a metal salt of a higher fatty acid as a stabilizer. However, this technique has a problem that the flame retardancy is lowered and the high flame retardancy performance inherent to the flame retardant cannot be exhibited. In addition, as an example of application to a styrene-based resin, Patent Document 2 proposes a technique of adding an organic solvent solution, but the solvent used is scattered outside the system without remaining in the product, It is not an environmentally good method.

  On the other hand, flame retardants such as tetrabromobisphenol-A-bis (2,3-dibromopropyl ether) and tris (2,3-dibromopropyl) isocyanurate have recently been changed to HBCD as described in Patent Document 3. Proposed as a flame retardant. However, these flame retardants are insufficient for obtaining flame retardant performance when used alone, and use in combination with tetrabromobisphenol allyl ether or tribromophenol allyl ether has been proposed. However, when an allyl ether compound is used in combination, when the amount of allyl ether compound necessary to express the required flame retardancy is compounded, the thermal stability becomes extremely poor, and various stabilizers are added. Is not improved enough.

In recent years, from the viewpoint of protecting the ozone layer, saturated hydrocarbon compounds such as propane and butane are often used as blowing agents in place of Freon.
For example, in order to obtain a foam having a high degree of heat insulation, such as three types of extruded polystyrene foam heat insulating plates defined in JIS A9511, it is preferable to leave more of the foaming agent. Depending on the body density, when the foam density is in the range of 20 to 40 kg / m ³ , 4.0% by weight or more for propane and 2.5% for butanes with respect to the weight of the foam. It is preferable to leave at least wt%, and it is considered preferable to leave at least 3.0 wt% of butanes.

  However, when a large amount of relatively flammable compounds such as aliphatic hydrocarbons typified by propane and butane remain, the flame retardancy specified in JIS A9511 may not be satisfied. On the other hand, in order to improve the flame retardancy, it is conceivable to increase the amount of the flame retardant to be added, but it is difficult to obtain a stable flame retardancy simply by increasing the amount of addition. In particular, although the styrene resin itself, which is the basic material of the foam, is flame retardant, the tendency that it is easy to ignite hydrocarbons that volatilize from the foam during combustion and it is difficult to suppress combustion is still difficult to solve. Furthermore, an increase in the amount of the flame retardant tends to cause deterioration in foam moldability, and it tends to be difficult to obtain a molded product with satisfactory quality.

  As described above, the technology that can satisfy the flame retardancy and thermal stability of the styrene-based extruded foam still leaves room for improvement.

Japanese Patent Publication No.31-5393 Japanese Patent Publication No.42-19195 Japanese Patent Publication No.51-25061 Japanese Patent Publication No.05-67654 Japanese Patent Laid-Open No. 2003-301064

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

As a result of intensive studies to solve the above problems, the present inventors have found that flame retardancy with excellent environmental compatibility can be obtained by using a mixed specific brominated flame retardant.
Furthermore, in the production of styrenic resin foams used as blowing agents containing saturated hydrocarbons, by using a boric acid-containing compound in combination, it is excellent despite the use of those containing saturated hydrocarbons as blowing agents. In particular, it is possible to suppress the ignition or combustion of hydrocarbons that volatilize from the foam during combustion, thereby achieving both high flame resistance and high thermal stability as defined in JIS A9511. I found out.

That is, the present invention
[1] A styrene resin foam obtained by heating and melting a styrene resin, adding a foaming agent, and extruding and foaming the foaming agent,
Containing 1 to 6 parts by weight of mixed brominated flame retardant with respect to 100 parts by weight of styrene resin,
Furthermore, 0.5-6 parts by weight of a boric acid-containing compound consisting of at least one selected from the group consisting of boric anhydride, boric acid, barium borate, magnesium borate, calcium borate,
The mixed brominated flame retardant is
(A) a mixed brominated flame retardant comprising tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) and tetrabromobisphenol-A-bis (2,3-dibromopropyl ether), or
(B) a mixed brominated flame retardant composed of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) and tris (2,3-dibromopropyl) isocyanurate;
And when the content of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) in the mixed brominated flame retardant is 100% by weight based on the total mixed brominated flame retardant, The present invention relates to a styrene resin extruded foam characterized by being 25% to 75% by weight.
[2] When the content of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) in the mixed brominated flame retardant is 100% by weight of the mixed brominated flame retardant, The styrene-based resin extruded foam according to [1], which is 35% by weight to 65% by weight.
[3] The extruded styrenic resin foam according to [1] or [2], wherein the boric acid-containing compound is boric anhydride.
[4] The styrenic resin foam according to any one of [1] to [3], wherein the foaming agent contains at least one selected from saturated hydrocarbons having 3 to 5 carbon atoms. About.
[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, [1 ] It relates to the styrene resin foam in any one of [4].
[6] In the combustion measurement specified in JIS A9511, the flame extinguishes within 3 seconds, there is no residue, it does not burn over the combustion limit indicator line, and the flame retardant satisfies the condition that the oxygen index is 26% or more It has a performance, It is related with the styrene resin foam in any one of [1]-[5].
[7] The styrenic resin foam according to any one of [1] to [6], which has a heat insulation performance of 0.028 W / mK or less in the measurement of thermal conductivity defined in JIS A9511. About.
[8] A method for producing a styrenic resin foam obtained by heating and melting a styrenic resin, adding a foaming agent, and extruding and foaming the foaming agent,
Containing 1 to 6 parts by weight of mixed brominated flame retardant with respect to 100 parts by weight of styrene resin,
Furthermore, 0.5-6 parts by weight of a boric acid-containing compound consisting of at least one selected from the group consisting of boric anhydride, boric acid, barium borate, magnesium borate, calcium borate,
The mixed brominated flame retardant is
(A) a mixed brominated flame retardant comprising tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) and tetrabromobisphenol-A-bis (2,3-dibromopropyl ether), or
(B) a mixed brominated flame retardant composed of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) and tris (2,3-dibromopropyl) isocyanurate;
And when the content of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) in the mixed brominated flame retardant is 100% by weight based on the total mixed brominated flame retardant, The present invention relates to a method for producing a styrene-based resin extruded foam, which is 25% by weight to 75% by weight.

  According to the present invention, it is possible to stably produce a styrenic resin foam excellent in flame retardancy and heat stability even when a material containing a saturated hydrocarbon is used as a foaming agent. It becomes. The styrenic resin foam of the present invention is particularly useful for use as a heat insulating material for construction due to its excellent performance.

  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. Random, block or graft copolymers; post-brominated polystyrene, modified polystyrene such as rubber reinforced polystyrene, 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, butyl acrylate, and acrylonitrile; Diene compounds 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 polystyrene, maleic anhydride-modified polystyrene, impact-resistant polystyrene, and the like are preferable from the viewpoint of extrusion foam moldability and the like. Styrene homopolymer is more preferable from the viewpoint of cost.

  The styrene resin that can be used in the present invention is not limited to virgin resin, and recycled styrene resin can also be used. Examples include fish box EPS, home appliance cushioning materials, styrene resin foams such as food foam polystyrene trays, or polystyrene trays as refrigerator interior materials. Separately from this, a styrenic resin obtained by recycling cutting waste generated in the finish cutting process of the product can also be used. These styrenic resins may be fed as they are into the extruder, or may be reduced in volume and pelletized so as to be easily fed into the extruder.

  In the present invention, the flame retardant comprises (A): tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) and tetrabromobisphenol-A-bis (2,3-dibromopropyl ether). Mixed brominated flame retardant, or mixed brominated flame retardant consisting of (B): tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) and tris (2,3-dibromopropyl) isocyanurate By containing a flame retardant, flame retardance can be imparted to the resulting styrene resin foam.

The content of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) contained in the mixed brominated flame retardant (A) or (B) in the styrene resin extruded foam of the present invention is: When the total mixed brominated flame retardant is 100% by weight, it is preferably 25% by weight to 75% by weight.
The reason is not clear, but it is obtained when the tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) contained in the mixed brominated flame retardant is in the range of 25 to 75% by weight. Regarding the flame retardant performance of the extruded foam, the high flame retardant performance of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) may have an effect, or tetrabromobisphenol-A which is the mixing partner. -The low flame retardancy which was the disadvantage of bis (2,3-dibromopropyl ether) or (2,3-dibromopropyl) isocyanurate is counteracted, as if tetrabromobisphenol-A-bis (2,3-dibromo-2 -Highly flame retardant performance as if it was a single methylpropyl ether). On the other hand, regarding the thermal stability of the extruded foam obtained, the content of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether), which has a low thermal stability performance, can be reduced, Since it can contain highly stable tetrabromobisphenol-A-bis (2,3-dibromopropyl ether) or (2,3-dibromopropyl) isocyanurate, the thermal stability is tetrabromobisphenol-A- Bis (2,3-dibromo-2-methylpropyl ether) can be made higher than using it alone.

When tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) is less than 25% by weight with respect to 100% by weight of the mixed flame retardant, the obtained flame retardancy tends to be low, and 75% by weight. When it exceeds%, thermal stability tends to deteriorate.
In consideration of the dispersion and variation of the flame retardant in the styrene resin, when trying to stably obtain higher flame retardancy and higher thermal stability, tetrabromobisphenol-A-bis (2 , 3-dibromo-2-methylpropyl ether) is preferably in the range of 35 to 65% by weight.

The content of the mixed brominated flame retardant in the styrene resin extruded foam of the present invention can obtain the combustibility specified in JIS A9511, and the thermal stability of the styrene resin in the extruder during foam production. The amount of foaming agent added, the density of the foam, and depending on the case, the type or amount of other additives may be appropriately adjusted so that it can be maintained. 1 to 6 parts by weight is preferable.
When the content of the mixed 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. When the content exceeds 6 parts by weight, stability during foam production And surface properties may be impaired.

  The styrene resin extruded foam of the present invention further contains a boric acid-containing compound consisting of at least one selected from the group consisting of boric anhydride, boric acid, barium borate, magnesium borate and calcium borate. By this, it becomes possible to express a more advanced flame retardancy. Of the boric acid-containing compounds, boric anhydride is preferable.

  In the present invention, the content of the boric acid-containing compound is preferably 0.5 to 6 parts by weight with respect to 100 parts by weight of the styrene resin. If the content of the boric acid-containing compound is less than 0.5 parts by weight, there is a tendency that ignition or combustion of hydrocarbons that volatilize from the foam during combustion cannot be suppressed, and even if it exceeds 6 parts by weight, the flame retardant performance changes. Because there is not, it becomes disadvantageous in cost and cannot find a special effect.

Although it does not specifically limit as a foaming agent used by this invention, The outstanding environmental compatibility can be provided by using 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 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, when water or alcohol is used as the other foaming agent, it is preferable to add a water-absorbing substance in order to stably perform extrusion foaming. Specific examples of water-absorbing substances used in the present invention include polyacrylate polymers, starch-acrylic acid graft copolymers, polyvinyl alcohol polymers, vinyl alcohol-acrylate copolymers, 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 particles having a hydroxyl group on the surface and having a particle diameter of 1000 nm or less; 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, processing aids such as fatty acid metal salts, fatty acid amides, fatty acid esters, liquid paraffin, and olefinic wax, flame retardants other than those described above, and antistatic properties, as long as they do not inhibit the effects of the present invention. Additives such as colorants such as agents and pigments can be included.

  Furthermore, in the present invention, if necessary, a phenolic antioxidant, a phosphorus stabilizer, a nitrogen stabilizer, a sulfur stabilizer, a lactone stabilizer, a benzotriazole / hindered amine-based stabilizer, etc. An agent can be contained.

  Specific stabilizers include phosphorus-based stabilizers such as tris (2,4-di-t-butylphenyl) phosphite and bis (2,6-t-butyl-4-methylphenyl) -pentaerythritol diphosphite. Agent, bis (2,2,6,6-tetramethyl-4-piperidinyl) decanedioate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl), bis (decanedioate) ( 2,2,6,6-tetramethyl-1 (octyloxy-4-piperidinyl), tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxyl Hindered amine stabilizers such as Lato, ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate], pentaerythritol tetra [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], etc. These may be used alone or in combination. In particular, phosphorus stabilizers such as tris (2,4-di-t-butylphenyl) phosphite and bis (2,6-t-butyl-4-methylphenyl) -pentaerythritol diphosphite , Decanedioic acid bis (2,2,6,6-tetramethyl-4-piperidinyl), decanedioic acid bis (1,2,2,6,6-pentamethyl-4-piperidinyl), decanedioic acid bis (2 , 2,6,6-tetramethyl-1 (octyloxy-4-piperidinyl), tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate Such This hindered amine stabilizer is preferably used because it does not lower the flame retardancy of the foam and improves the thermal stability of the foam.

  The addition amount of the stabilizer in the present invention is preferably 0.01 to 0.5 parts by weight, and more preferably 0.02 to 0.3 parts by weight with respect to 100 parts by weight of the styrene resin.

  As a method for producing a styrene resin extruded foam of the present invention, a styrene resin, a brominated flame retardant, other additives, etc. are supplied to heating and melting means such as an extruder, and under high pressure conditions at any stage. It is produced by adding a foaming agent to a styrenic resin, forming a fluid gel, cooling to a temperature suitable for extrusion foaming, and then extruding and foaming the fluid gel into a low pressure region through a die to form a foam.

  As a form of heat melting such as styrene resin, bromine flame retardant, and other additives, after mixing bromine flame retardant and other additives with styrene resin, heat and melt; styrene resin After heating and melting, add and mix brominated flame retardant and other additives; prepare brominated flame retardant, stabilizer and other additives in styrene resin in advance, then prepare heated and melted composition Then, it is supplied again to the extruder and melted by heating.

  There are no particular restrictions on the heating temperature, melt kneading time, and melt kneading means when heating and kneading the styrene resin and additives such as a foaming agent. Although heating temperature should just be more than the temperature which the styrene resin to use melt | dissolves, the temperature which suppresses the molecular degradation of resin as much as possible including the influence of a flame retardant etc., for example, about 150-250 degreeC is preferable. 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 flame retardancy, heat insulating properties and thermal stability.

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.
Unless otherwise specified, “parts” represents parts by weight and “%” represents% by weight.

The raw materials used in the examples and comparative examples are as follows.
(1) Styrenic resin [PS940, G9401]
(2) Mixed brominated flame retardant Mixed brominated flame retardant (A)
Tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether [Pyroguard SR-130, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.]
Tetrabromobisphenol A-bis (2,3-dibromopropyl) ether [Daiichi Kogyo Seiyaku Co., Ltd., Pyroguard SR-720]
Mixed brominated flame retardant (B)
Tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether [Pyroguard SR-130, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.]
Tris (2,3-dibromopropyl) isocyanurate [Nippon Kasei Co., Ltd., TAIC-6B]
(3) Boric acid-containing compound / boric anhydride [manufactured by USBORAX, boric anhydride]
・ Magnesium borate [Tonda Pharmaceutical Co., Ltd., magnesium borate]
(4) Foaming agent, isobutane [Mitsui Chemicals, Inc.]
・ Normal butane [manufactured by Iwatani Corporation]
・ Dimethyl ether [Mitsui Chemicals, Inc.]
・ Water [tap water]
(5) 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 was determined based on foam density (g / cm ³ ) = foam weight (g) / foam volume (cm ³ ), and the unit was expressed in terms of (kg / m ³ ).

(2) Average cell diameter (mm)
The cell diameter in each direction was measured according to ASTM D-3576.
The cross-section in the width direction of the foam is enlarged and projected 50 to 100 times, and the cell diameter (HD) in the thickness direction and the cell diameter (TD) in the width direction are measured. Next, the cross section in the extrusion direction was enlarged and projected, and the cell diameter (MD) in the extrusion direction was measured.
The average cell diameter was calculated from the following formula by taking the cube of the product of the cell diameters in each direction.
Average cell diameter = (HD x TD x MD) ^1/3

(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 five flame extinguishing times are within 3 seconds.
○: At least one of the five flame extinguishing times exceeds 3 seconds, but the remaining three or more are within 3 seconds.
Δ: At least 3 out of 5 flame extinguishing times exceed 3 seconds, but the remaining one or more are within 3 seconds.
X: All 5 flame extinguishing times exceed 3 seconds.
Burning distance
A: All five stops within the limit line.
○: At least one of the five lines decreases over the limit line, but the remaining three or more lines stop burning within the limit line.
Δ: Combustion exceeds the limit line for at least three of the five, but combustion stops within the limit line for the remaining one or more.
X: Combustion exceeds the limit line with all five.
Combustion status
(Double-circle): Combustion of a foaming agent is not seen at all.
○: Some burning of the foaming agent is observed.
Δ: Combustion of the foaming agent is observed, but no complete burning occurs.
X: Combustion of the foaming agent is also observed, and it is completely burned.

(4) Oxygen index About the foam which passed 7 days after manufacture, according to JISK7201, it measured using the test piece of thickness 10mm * length 150mm * width 10mm.
A: 29% or more.
○: 26% or more and less than 29%.
X: Less than 26%.

(5) Specific Viscosity Reduction Rate of Foam In order to evaluate the degree of resin deterioration associated with the heat history in the extruder, the specific viscosity reduction rate of the foam was determined by the following procedure.
a) About 1 g of 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.
b) 250 mg of the obtained resin content is dissolved in 25 mL of toluene, and the specific 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 specific viscosity is calculated by the following formula.
Specific viscosity (ηsp) = (sample transit time) / (chloroform transit time) −1
c) The rate of decrease in the specific viscosity (ηsp (foam)) of the foam relative to the resin specific viscosity (ηsp (resin)) used is calculated by the following equation.
Specific viscosity reduction rate of foam = specific viscosity of foam (ηsp (foam)) / specific viscosity of resin used (ηsp (resin))
The obtained values were judged according to the following criteria.
○: The specific viscosity reduction rate of the foam is 0.85 or more.
(Triangle | delta): The specific viscosity fall rate of a foam is 0.75 or more and less than 0.85.
X: The specific viscosity reduction rate of a foam is less than 0.75.

(6) Thermal conductivity It measured according to JIS A9511 about the foam which passed 7 days after manufacture.
A: Less than 0.0260 W / mK.
○: 0.0260 W / mK or more and less than 0.0285 W / mK.
X: 0.0285 W / mK or more.

Example 1
4 parts by weight of mixed brominated flame retardant with respect to 100 parts of polystyrene resin (G9401), and tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether and tetrabromobisphenol A therein -A resin mixture comprising 3 parts by weight of boric acid anhydride and 1.5 parts of talc as a boric acid-containing compound was formulated so that the ratio of bis (2,3-dibromopropyl ether) was 37.5: 62.5. 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, 3.5 weight part of isobutane and 3 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. It turns out that the outstanding performance is expressed compared with Comparative Examples 1-5.

(Examples 2-7, Reference Example 1, Comparative Examples 1-5)
As shown in Table 1, Example 1 except that the type and amount of mixed brominated flame retardant, the type and amount of boric acid-containing compound, the type and amount of blowing agent, and the type and amount of other additives were changed. A foam was obtained by the same operation as in.

As is clear by comparing Examples 1 to 7 and Comparative Examples 1 to 5, the type and amount of the mixed brominated flame retardant and the type and amount of the boric acid-containing compound are specified with respect to 100 parts by weight of the styrene resin. It can be seen that an extruded foam having improved flame retardancy and thermal stability can be obtained stably.

Claims (8)

A styrenic resin foam obtained by melting a styrenic resin by heating, adding a foaming agent, and extruding and foaming this,
Containing 1 to 6 parts by weight of mixed brominated flame retardant with respect to 100 parts by weight of styrene resin,
Furthermore, 0.5-6 parts by weight of a boric acid-containing compound consisting of at least one selected from the group consisting of boric anhydride, boric acid, barium borate, magnesium borate, calcium borate,
The mixed brominated flame retardant is
(A) a mixed brominated flame retardant comprising tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) and tetrabromobisphenol-A-bis (2,3-dibromopropyl ether), or
(B) a mixed brominated flame retardant composed of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) and tris (2,3-dibromopropyl) isocyanurate;
And when the content of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) in the mixed brominated flame retardant is 100% by weight based on the total mixed brominated flame retardant, A styrene-based resin extruded foam, characterized by being 25% to 75% by weight.   The content of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) in the mixed brominated flame retardant is 35% when the total mixed brominated flame retardant is 100% by weight. The styrene resin extruded foam according to claim 1, wherein the styrene resin extruded foam is 1% to 65% by weight.   The styrene resin extruded foam according to claim 1 or 2, wherein the boric acid-containing compound is boric anhydride. The styrenic resin foam according to any one of claims 1 to 3, wherein the foaming agent contains at least one selected from saturated hydrocarbons having 3 to 5 carbon atoms.   The foaming agent further comprises 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. 5. The styrene resin foam according to any one of 4 above.   In the combustion measurement specified in JIS A9511, flame extinguishes within 3 seconds, there is no residue, it does not burn beyond the combustion limit indicator line, and it has flame retardant performance that satisfies the condition that the oxygen index is 26% or more The styrenic resin foam according to any one of claims 1 to 5, wherein   The styrenic resin foam according to any one of claims 1 to 6, which has a heat insulating performance of 0.028 W / mK or less in the measurement of thermal conductivity defined in JIS A9511. A method for producing a styrene resin foam by heating and melting a styrene resin, adding a foaming agent, and extruding and foaming this,
Containing 1 to 6 parts by weight of mixed brominated flame retardant with respect to 100 parts by weight of styrene resin,
Furthermore, 0.5-6 parts by weight of a boric acid-containing compound consisting of at least one selected from the group consisting of boric anhydride, boric acid, barium borate, magnesium borate, calcium borate,
The mixed brominated flame retardant is
(A) a mixed brominated flame retardant comprising tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) and tetrabromobisphenol-A-bis (2,3-dibromopropyl ether), or
(B) a mixed brominated flame retardant composed of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) and tris (2,3-dibromopropyl) isocyanurate;
And when the content of tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether) in the mixed brominated flame retardant is 100% by weight based on the total mixed brominated flame retardant, A method for producing an extruded foam of a styrenic resin, characterized by being 25% by weight to 75% by weight.