JP2005248051A - Flame retardant foamed styrene resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of resin properties and metal corrosion of an apparatus due to bromine radicals generated by early thermal decomposition of a bromine flame retardant in a flame retardant foamed styrene resin composition which is extruded in a molten state by press-fitting a foaming agent. To prevent.
SOLUTION: A flame retardant foamed styrenic resin composition in which a foaming agent is press-fitted at or before melting and is extruded in a molten state,
(A) per 100 parts by weight of styrenic resin,
(B) 0.3 to 20 parts by weight of a bromine flame retardant in which at least a part of bromine is bonded to an aliphatic carbon chain or an aliphatic hydrocarbon ring;
(C) 0.1 to 20 parts by weight of particles having an average particle size of 0.1 to 50 μm selected from the group consisting of organic compounds and resins having a melting point or softening point of 220 ° C. or higher, and zirconium oxide;
(D) A flame-retardant foamed styrene resin composition, wherein the total amount of inorganic compounds (excluding zirconium oxide) does not exceed 0.3 parts by weight.
[Selection figure] None

Description

  The present invention relates to a resin composition for producing a flame retardant styrene resin foam which is melt-extruded by adding a foaming agent to a styrene resin containing a brominated flame retardant.

  A foam formed by press-fitting a foaming agent such as pentane into molten polystyrene and extruding it from the die of an extruder into the atmosphere is widely used as a heat insulating material. When used for building materials, the foamed molded product is required to have self-extinguishing properties according to JIS A 9511 (1995) and the fire extinguishing law, that is, flame retardancy. Therefore, a brominated flame retardant having an action mechanism of generating bromine radicals that capture active radicals generated by thermal decomposition of the resin is added to the resin. A number of brominated flame retardants are known, but currently the most commonly used flame retardant for expanded polystyrene is hexabromocyclododecane (HBCD).

  In general, brominated flame retardants decompose at a temperature somewhat lower than the decomposition temperature of the resin itself, and it is necessary to release bromine radicals. However, HBCD is partially heated at the molding temperature of expanded polystyrene (about 200 ° C.). Since it decomposes and releases bromine radicals, it causes coloration and deterioration of the resin, and there are disadvantages that cause metal corrosion such as kneaders and extruders by the released bromine radicals. Similar drawbacks are observed for brominated flame retardants having a relatively small bromine-carbon bond energy other than HBCD.

  In order to eliminate or reduce this drawback, it has been proposed to use a thermal stabilizer that prevents premature thermal decomposition of the brominated flame retardant. For example, see JP-B-59-43060 (organotin compound and organophosphorus compound), JP-A-60-139737 (epoxy compound), and JP-B-60-29744 (lead stearate). However, expanded polystyrene moldings containing these heat stabilizers limit the rate at which they can be mixed into a new resin after recycling.

  The present inventors have surprisingly found that the foam nucleating agent and the air conditioner (such as talc) used to improve cell uniformity and foam stability when producing expanded polystyrene have bromine-carbon bond energy. It has been discovered that it promotes early thermal decomposition of relatively small brominated flame retardants and causes resin coloring during molding and corrosion of equipment. Similarly, substances that promote early thermal decomposition of brominated flame retardants include inorganic additives such as pigments and inorganic flame retardant aids.

  Therefore, the present invention uses organic compound or resin or zirconium oxide particles that do not have an action of promoting early thermal decomposition of brominated flame retardants, instead of inorganic foam nucleating agent / bubble adjusting agent represented by talc. .

The present invention is a flame retardant foamed styrenic resin composition that is injected with a foaming agent at the time of melting or before and is extruded in a molten state,
(A) per 100 parts by weight of styrenic resin,
(B) 0.3 to 20 parts by weight of a brominated flame retardant in which at least a part of bromine is bonded to an aliphatic hydrocarbon chain or an aliphatic hydrocarbon ring;
(C) 0.1 to 20 parts by weight of particles having an average particle size of 0.1 to 50 μm selected from the group consisting of organic compounds and resins having a melting point or softening point of 220 ° C. or higher, and zirconium oxide;
(D) The composition is characterized in that the total amount of inorganic compounds (excluding zirconium oxide) does not exceed 0.3 parts by weight.

The styrenic resin referred to here can be copolymerized not only with a styrene homopolymer, that is, polystyrene, but also with a homopolymer of a styrene derivative such as vinyltoluene and α-methylstyrene, or a small proportion of styrene or a styrene derivative. It means vinyl monomers and their copolymers. Styrenic resins also include polymer blends or polymer alloys in which a small proportion of rubber is blended to improve physical properties such as impact resistance.
Brominated flame retardants in which at least some bromine is bonded to an aliphatic hydrocarbon chain or aliphatic hydrocarbon ring are not necessarily required to have all bromine bonded to an aliphatic hydrocarbon chain or ring. It means that the remaining bromine may be bonded to the aromatic hydrocarbon ring. Bromine bonded to an aliphatic hydrocarbon chain or ring has a lower bromine-carbon bond energy than bromine bonded to an aromatic ring, and thus has a large flame retarding effect, but is inferior in thermal stability during extrusion. Yes.

  Examples of such specific compounds are dibromoethyldibromocyclohexane, tetrabromocyclooctane, hexabromocyclododecane (HBCD), brominated limonene, pentabromo, where all bromines are bonded to an aliphatic hydrocarbon chain or ring. Benzyl bromide, tris (2,3-dibromopropyl) cyanurate, tris (2,3-dibromoisobutyl) cyanurate, tris (2,3-dibromopropyl) isocyanurate, tris (2,3-dibromoisobutyl) isocyanurate, tri Bromoneopentyl alcohol, chloropentabromocyclohexane, tris (2,3-dibromopropyl) phosphate, tris (2,3-bromochloropropyl) phosphate, tris (tribromoneopentyl) phosphate, bis (2,3 Tribromophenol-2,3-dibromo, such as dibromopropyl) -2,3-dichloropropyl phosphate, where some bromine is bound to an aliphatic hydrocarbon chain or ring and the remaining bromine is bound to an aromatic ring Propyl ether, tribromophenol-2,3-dibromoisobutyl ether, tetrabromobisphenol A-bis (2,3-dibromopropyl) ether, tetrabromobisphenol S-bis (2,3-dibromopropyl) ether, tetrabromobisphenol F-bis (2,3-dibromopropyl) ether, tetrabromobisphenol A-bis (2,3-dibromoisobutyl) ether, tetrabromobisphenol S-bis (2,3-dibromoisobutyl) ether, tetrabromobisphenol F- Screw (2,3 Dibromo isobutyl) ether, and the like.

  The reason why an organic compound or resin having an average particle size of 0.1 to 50 μm used in place of an inorganic foam nucleating agent / bubble regulator represented by talc has a melting point or softening point of 220 ° C. or higher This is because it is necessary to maintain the particle state at the extrusion molding temperature (about 200 ° C.) of the styrene resin. Of course, zirconium oxide does not melt at such temperatures. Of the many such organic compound / resin particles, particles prepared from raw materials frequently used in the field of synthetic resin industry are preferred. One of them is brominated flame retardant particles in which all bromine is bonded to the aromatic ring. Examples of specific compounds are decabromodiphenyl ether, bis (pentabromophenyl) ethane, bis (tribromophenoxy) ethane. Bis (pentabromophenoxy) ethane, tris (tribromophenoxy) triazine, octabromotrimethylphenylindane, tetrabromophthalic anhydride, ethylenebistetrabromophthalimide and the like. These brominated flame retardant particles not only have high thermal stability, but also contribute to flame retardancy of styrene resins. The other is thermosetting synthetic resin particles after being cured to an insoluble and infusible state, and specific examples thereof include melamine resin, urea resin, phenol resin, epoxy resin, urethane resin, and the like. Resin powders such as polycarbonate, polyester, polyamide, polyphenylene ether, polyaryl ether ketone, polyaryl sulfone, polyimide, polyamide imide, etc., whose melting point is raised to 290 ° C. or higher, called a heat resistant resin, can also be used. A method of pulverizing these flame retardants or resins in an average particle size range of 0.1 to 50 μm is arbitrary, but commercially available products may be used.

  Foaming agents used for extrusion foaming are known. Examples thereof are propane, butane, pentane, hexane, 1-chloro-1,1-difluoroethane, monochlorodifluoromethane, monochloro-1,2,2,2-tetrafluoroethane, 1,1-difluoroethane, 1,1,1, It is an aliphatic and halogenated hydrocarbon such as 2-tetrafluoroethane, 1,1,3,3,3-pentafluoropropane and methylene chloride, water, nitrogen, or an azo-based chemical blowing agent.

  Although not essential, a phosphorus-based flame retardant can be used in combination with a brominated flame retardant. The combined use of the phosphorus-based flame retardant has the effect of reducing the amount of brominated flame retardant added to achieve the desired flame retardant level. Depending on the type, there is an effect of appropriately plasticizing the styrene resin. Here, the phosphorus-based flame retardant means an organic phosphorus compound having a phosphorus content of 6 wt% or more and containing no halogen. Aromatic phosphate esters and phosphazene compounds are preferred. Examples thereof are triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, diphenyl-cresyl phosphate, resorcinol-bis (diphenyl) phosphate, bisphenol A-bis (diphenyl) phosphate, resorcinol-bis (dicresyl) phosphate, Bisphenol A-bis (dicresyl) phosphate, resorcinol-bis (di-2,6-xylenyl) phosphate, phenoxyphosphazene, methylphenoxyphosphazene, cresyl phosphazene, xylenoxyphosphazene, methoxyphosphazene, ethoxyphosphazene, propoxyphosphazene, etc. .

  Inorganic additive components that should not be added in order to induce or accelerate premature thermal decomposition of a flame retardant in which at least a part of bromine used in the present invention is bonded to an aliphatic hydrocarbon chain / ring are talc and the like described above. In addition to the foam nucleating agent / bubble regulator, all inorganic additives. However, since it has been confirmed that zirconium oxide has no such action, it is excluded from the components that should not be added. Examples of ingredients that should not be added include nucleating agents / foam regulators such as talc, bentonite, diatomaceous earth, aerosil, silica gel, magnesium silicate, inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide, antimony trioxide, Flame retardant aids such as antimony pentoxide, zinc borate, boric acid, calcium oxide, magnesium oxide, tin oxide, molybdenum oxide, heat stabilizers such as zeolite, hydrotalcite, titanium oxide, titanium yellow, zinc oxide, white It is a pigment such as carbon.

  The blending amount of the brominated flame retardant described above varies depending on the bromine content of the specific flame retardant, the desired flame retardant level, the type of styrene resin, etc., but is generally 0.3 per 100 parts by weight of the styrene resin. -20 parts by weight, preferably 1.0-10 parts by weight.

  The compounding amount of particles having an average particle diameter of 0.1 to 50 μm selected from the group consisting of an organic compound and resin having a melting point or softening point of 220 ° C. or higher, and zirconium oxide is also the specific particle type and particle size, and the addition of a foaming agent The amount varies depending on the amount, the bulk density of the foam, etc., and is generally 0.1 to 20 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.1 to 5.0 parts by weight per 100 parts by weight of the resin. .

  The phosphorus-based flame retardant as an optional additive is up to 30 parts by weight, preferably up to 5 parts by weight per 100 parts by weight of the resin.

  As described above, the inorganic additive component should not be blended in principle. However, blending is permitted as long as it is a trace amount that does not adversely affect the early thermal stability of the brominated flame retardant. The upper limit would therefore be 0.3 parts by weight per 100 parts by weight of resin.

  The resin composition of the present invention can contain conventional organic additives used for styrenic resins. Examples thereof are antioxidants, UV absorbers, UV stabilizers, organic color pigments, organic fillers, anti-dripping agents, crystal nucleating agents, antistatic agents, radical generators, compatibilizers and the like. These conventional additives are commercially available, and specific chemical names and amounts used are described in the manufacturer's catalog and plastic processing handbook.

  The mixing method of the additive component to the styrenic resin may be premixed with the additive component excluding the resin and the foaming agent and supplied to the extruder in advance, or may be separately supplied proportionally to the extruder. . These are heated in an extruder and mixed uniformly by melting, plasticizing and kneading. Foam molding is performed by press-fitting a foaming agent (pentane or the like) at the time when the melting of the resin is completed in an extruder and extruding it from the die into the atmosphere. The amount of the blowing agent injected is generally 0.005 to 0.07 mol, preferably 0.01 to 0.05 mol, per 100 parts by weight of the resin. Instead of press-fitting into the molten resin, a foaming agent may be impregnated into the resin pellets in advance.

  The invention is illustrated by the following examples and comparative examples. In these, “parts” and “%” are based on weight unless otherwise specified. The raw materials used are as follows.

(A) Styrenic resin General purpose polystyrene, Toyostyrene G220 (Toyo Styrene Co., Ltd.)
(B) Brominated flame retardant B1: Hexabromocyclododecane (HBCD)
B2: Tetrabromobisphenol A-bis (2,3-dibromoisobutyl) ether B3: Tetrabromobisphenol A-bis (2,3-dibromopropyl) ether B4: Tris (tribromoneopentyl) phosphate B5: Tris (2, 3-dibromopropyl) isocyanurate (C) organic compound / resin particles C1: decabromodiphenyl ether (average particle size 2.2 μm), FR-1 210 manufactured by DSBG
C2: bis (pentabromophenyl) ethane (average particle size 3.4 μm), SAYTEX 8010 manufactured by Albemarle
C3: Ethylenebistetrabromophthalimide (average particle size: 1.0 μm), SAYTEX BT-93 manufactured by Albemarle
C4: Melamine resin powder (average particle size 33 μm), m. p. (Decomposition)> 300 ° C
C5: Zirconium oxide (average particle size 1.1 μm)
(D) Inorganic additive component (for comparative example)
D1: talc D2: bentonite D3: antimony trioxide (E) phosphorus flame retardant: triphenyl phosphate (F) heat stabilizer: bis (2,6-di-t-butylphenyl) pentaerythritol diphosphite (G) Hindered phenolic antioxidant (HDP): pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]
(H) Foaming agent: pentane Average particle size measurement method:
A 0.1 g sample was added to 10 ml of a 2 wt% phosphate ester-based anionic active surfactant aqueous solution and dispersed for 10 minutes with ultrasonic waves, and the median diameter was measured using a Shimadzu SALD-2000.

[Example 1-14 and Comparative Example 1-8]
How to make a specimen:
The formulations shown in Tables 1 and 2 except for the foaming agent were charged into a two-stage extruder in which a first heating cylinder having a diameter of 65 mm and a second heating cylinder having a diameter of 90 mm were connected in series, and the first heating was performed. Heat to 200 ° C. in a tube to melt, plasticize and knead. A predetermined amount of foaming agent is press-fitted in a separate line from the tip of the first heating cylinder (connection end with the second heating cylinder), the resin temperature is cooled to 120 ° C. in the second heating cylinder, and the second heating Extruded into the atmosphere from a die lip having a cross section of 2.5 mm × 45 mm attached to the tip of the cylinder to obtain a plate-like extruded foam.

Visual evaluation of foam:
The foam was visually evaluated according to the following criteria.
○: There were no cracks, cracks, voids, etc., and a good foam was stably obtained.
X: Gas was ejected from the die, and a good foam was not stably obtained. In addition, cracks, cracks, voids, etc. were observed in the foam.
Flame retardant test:
The oxygen index was determined according to JIS K 7201.
Self-extinguishing:
In the flame retardancy test, those having an oxygen index of 26 or more were given: ○, and those having less than 26 were given: ×.
Thermal stability test:
The foam was pressed at room temperature, 0.5 g of finely chopped pieces were put in a Pyrex test tube, heated at 220 ° C. for 30 minutes, and after cooling, 5 g of chloroform was poured into the test tube and dissolved to prepare a sample. The color of this solution was evaluated by Gardner color number.
The results are shown in Tables 1 and 2.

[Discussion]
In all the examples, the state of the foam is good, the flame retardancy (including self-extinguishing properties), and the stability during heating (coloring) are also satisfactory. In contrast, in Comparative Example 1-4 in which zirconium oxide or organic compound / resin particles were not added, although the flame retardancy was satisfactory, the state of the foam was not satisfactory, and Comparative Example 5-8 was the state of the foam. Not satisfying all of flame retardancy and thermal stability at the same time. In particular, coloring during heating is remarkable.

Claims (6)

A flame-retardant foamed styrenic resin composition that is injected with a foaming agent at or before melting and is extruded in a molten state,
(A) per 100 parts by weight of styrenic resin,
(B) 0.3 to 20 parts by weight of a brominated flame retardant in which at least a part of bromine is bonded to an aliphatic carbon chain or an aliphatic hydrocarbon ring,
(C) 0.1 to 20 parts by weight of particles having an average particle size of 0.1 to 50 μm selected from the group consisting of organic compounds and resins having a melting point or softening point of 220 ° C. or higher, and zirconium oxide;
(D) A flame-retardant foamed styrene resin composition, wherein the total amount of inorganic compounds (excluding zirconium oxide) does not exceed 0.3 parts by weight.   The brominated flame retardant (B) is dibromoethyldibromocyclohexane, tetrabromocyclooctane, hexabromocyclododecane, brominated limonene, pentabromobenzyl bromide, tris (2,3-dibromopropyl) cyanurate, tris (2,3 -Dibromoisobutyl) cyanurate, tris (2,3-dibromopropyl) isocyanurate, tris (2,3-dibromoisobutyl) isocyanurate, tribromoneopentyl alcohol, chloropentabromocyclohexane, tris (2,3-dibromopropyl) Phosphate, tris (tribromoneopentyl) phosphate, bis (2,3-dibromopropyl) -2,3-dichloropropyl phosphate, tribromophenol-2,3-dibromopropyl ether, tri Lomophenol-2,3-dibromoisobutyl ether, tetrabromobisphenol A-bis (2,3-dibromopropyl) ether, tetrabromobisphenol S-bis (2,3-dibromopropyl) ether, tetrabromobisphenol F-bis ( 2,3-dibromopropyl) ether, tetrabromobisphenol A-bis (2,3-dibromoisobutyl) ether, tetrabromobisphenol S-bis (2,3-dibromoisobutyl) ether, or tetrabromobisphenol F-bis (2 , 3-Dibromoisobutyl) ether.   The composition according to claim 1 or 2, wherein the organic compound particles (C) are brominated flame retardants in which all bromine is bonded to an aromatic ring.   The composition according to claim 1 or 2, wherein the resin particles (C) are a cured thermosetting resin or a heat-resistant resin.   The composition according to any one of claims 1 to 4, further comprising up to 30 parts by weight of a phosphorus flame retardant having a phosphorus content of 6% by weight or more per 100 parts by weight of the styrene resin.   A method for producing a flame-retardant styrene resin foam, comprising melting the composition according to any one of claims 1 to 5 in an extruder, press-fitting an appropriate amount of a foaming agent, and then extruding the composition into the atmosphere.