JP7718009B2 - Flame retardant composition for polyurethane foam and flame retardant polyurethane foam containing the same - Google Patents

Description

The present invention relates to a flame retardant composition for polyurethane foam that does not use red phosphorus and that easily forms a charred layer without melting or dripping during combustion, and to a flame-retardant polyurethane foam containing the flame retardant composition for polyurethane foam.
The flame retardants of the present invention are applicable to either flexible or semi-rigid or rigid polyurethane foams.

Traditionally, polyurethane foam has been used not only as a sound-absorbing, sound-proofing, and heat-insulating material in automobiles and electrical appliances, but also as a heat-insulating measure for detached homes and condominiums, in a foam-in-place insulation method in which polyurethane foam is sprayed onto the surface of concrete members and interior wall materials. However, when used in automobiles and electrical appliances, high flame-retardant standards such as UL-94V are required. Furthermore, for architectural applications, polyurethane foam itself is flammable, so if a fire breaks out inside a building, it could lead to a major accident. The cone calorimeter test method addresses this issue. In this case, flame-retardant standards also require an extremely high level of flame-retardant performance, surpassing even UL-94V. Therefore, various methods have been developed to address these issues.

For example, in construction applications, a fire-resistant material made of a non-flammable inorganic coating material primarily composed of cement is sprayed onto sprayed polyurethane foam. However, because this method involves spraying a second fire-resistant material onto the polyurethane foam, it requires two spraying stages, and time must be allowed for the curing reaction to complete at each stage, which has the disadvantage of requiring time for construction and making process management difficult.

In addition, methods for improving the flame retardancy of polyurethane foams used in insulation for automobiles and electrical appliances have been attempted, such as making the polyurethane foam itself flame retardant or giving it self-extinguishing properties in case the polyurethane foam catches fire. These methods include blending a flame retardant into the polyurethane foam's raw materials and introducing a flame-retardant component into the polyurethane foam by copolymerization as one of its constituent components.

The most common method for improving the flame retardancy of polyurethane foam is to add flame retardants. This is because production costs are low, the type and amount of flame retardant added can be freely adjusted in post-production processes, and it is suitable for small-lot, high-mix production.

Traditionally, phosphate esters have been the primary flame retardants used in polyurethane foams. However, because phosphate esters have a plasticizing effect, they have the problem of causing shrinkage and a decline in the mechanical properties of polyurethane foam. Therefore, there is a need to reduce the amount of phosphate esters used and to find alternative flame retardants that do not adversely affect physical properties.

An alternative flame retardant is red phosphorus, which has relatively excellent flame retardancy. In fact, various flame retardant methods using red phosphorus have been proposed. For example, Patent Document 1 below discloses a flame-retardant polyurethane resin composition containing expandable graphite, polyphosphate or red phosphorus, and tricresyl phosphate in a polyurethane resin.
Furthermore, Patent Document 2 listed below describes a flame-retardant urethane resin composition that contains red phosphorus as an essential component in combination with other flame retardants such as phosphate esters.
Furthermore, hypophosphites may be used as flame retardants in thermoplastic resins. In this case, even if the flame retardancy measured by the oxygen index is somewhat excellent, it is unclear whether they can be used for urethane resins, which are used in applications requiring higher flame retardancy than thermoplastic resins.
Patent Document 3 listed below describes a thermoplastic polyamide composition containing a dialkyl phosphinate, which is an organic aluminum phosphinate. In this composition, the dialkyl phosphinate is selected and used in consideration of the stability of the melt of the thermoplastic polyamide.

Japanese Patent Application Laid-Open No. 2005-133054 Japanese Patent Application Laid-Open No. 2017-075326 Japanese Patent Application Laid-Open No. 2018-511685

However, although the red phosphorus used in Patent Documents 1 and 2 has high flame retardancy, it has a unique reddish hue, which may impart undesired coloring to the product. Furthermore, in order to balance coloring inhibition and flame retardancy, a considerable amount of a color-decoloring agent must be blended, which may result in problems such as a decrease in flame retardancy and poor light resistance of the color-decoloring agent. Furthermore, red phosphorus is a flammable substance, and its handling is regulated by the Fire Service Act, so its use presents safety issues.
Furthermore, the thermoplastic polyamide composition described in Patent Document 3 solves the problems inherent to flame retardant-containing thermoplastic polyamide compositions by selecting a specific organic aluminum phosphinate, and is not applicable to resins other than thermoplastic polyamides.

The present invention has been made in consideration of the above-mentioned conventional situation, and aims to provide a flame retardant composition for polyurethane foam that does not use red phosphorus, that easily forms a charred layer without melting or dripping during combustion, and that can exhibit high flame retardancy without using red phosphorus, and a flame-retardant polyurethane foam containing the flame retardant composition for polyurethane foam. The greatest challenge at present is that the above-mentioned very high level of non-combustibility criteria of the cone calorimeter test cannot be met without using red phosphorus, and therefore there is a need for a flame retardant composition that has high flame retardancy as an alternative to red phosphorus.
Furthermore, there is a demand for further reduction in the amount of shrinkage and weight loss rate when heated, which are characteristic of polyurethane foams.

As a result of intensive research to achieve the above-mentioned objective, the inventors have discovered that by using a flame retardant composition containing a phosphorus compound represented by the following formula (1) and, if necessary, a concomitant flame retardant, as a flame retardant composition for polyurethane foam, it is possible to obtain polyurethane foam with excellent flame retardancy, i.e., low total heat release, low maximum heat release rate, and low weight loss rate, as well as small shrinkage and weight loss rate in the transverse and thickness directions after testing. Specifically, the inventors have discovered that the use of the phosphorus compound represented by the following formula (1) makes it possible to obtain a flame retardant composition for polyurethane foam that easily forms a charred layer without melt dripping during combustion and exhibits high flame retardancy without using red phosphorus, and a flame-retardant polyurethane foam incorporating this flame retardant composition for polyurethane foam, thereby completing the present invention.

That is, the present invention provides:
(1) A flame retardant composition for polyurethane foam, comprising:
A phosphorus compound represented by the following formula (1):
and one or more combined flame retardants selected from the group consisting of melamine phosphate, melamine pyrophosphate, melamine polyphosphate, melamine phthalate, melamine, melamine cyanurate, ammonium polyphosphate, ammonium phosphate, zinc phosphate, non-halogenated phosphate esters, halogenated phosphate esters, bromine-based compounds, barium borate, borax, zinc borate, zinc stannate, magnesium hydroxide, aluminum hydroxide, antimony trioxide, antimony pentoxide, calcium molybdate, zinc molybdate, magnesium molybdate, magnesium silicate, hydrated gypsum, kaolin clay, mica, calcium carbonate, alumite, basic magnesium carbonate, calcium hydroxide, wollastonite, and a zeolite-structured clathrate compound of zinc hydrogen phosphate and ethylenediamine,
a flame retardant composition for polyurethane foams having excellent carbonization properties, the flame retardant composition comprising 0 to 600 parts by weight of a phosphorus compound represented by formula (1) per 100 parts by weight of the phosphorus compound;
(In the formula, M is Mg, Al, Ca, Ti, or Zn, and m is 2, 3, or 4.)

(2) The phosphorus compound represented by the formula (1) is an Al salt,
The flame retardant composition for polyurethane foam according to (1), wherein the combined flame retardant is one or more flame retardants selected from the group consisting of melamine, melamine cyanurate, melamine phosphate, melamine polyphosphate, diammonium hydrogen phosphate, ammonium polyphosphate, magnesium hydroxide, aluminum hydroxide, zinc borate, zinc stannate, antimony trioxide, antimony pentoxide, non-halogenated phosphate esters, halogenated phosphate esters, decabromodiphenylethane, trisdibromoneopentyl phosphate, wollastonite, and a zeolite-structured clathrate compound of zinc hydrogen phosphate and ethylenediamine.

(3) A flexible or semi-rigid flame-retardant polyurethane foam containing the flame retardant composition for polyurethane foam according to (1) or (2), which has excellent carbonization resistance and satisfies UL-94 V-0 without melting or dripping.
(4) A flexible or semi-rigid flame-retardant polyurethane foam having excellent carbonization performance according to (3), characterized in that the flame retardant composition for polyurethane foam contains the phosphorus compound represented by formula (1) and one or more combined flame retardants selected from the group consisting of melamine, melamine cyanurate, melamine polyphosphate, ammonium polyphosphate, and zinc borate, and the combined flame retardant is contained in an amount of 0 to 100 parts by weight per 100 parts by weight of the phosphorus compound represented by formula (1).

(5) A flexible or semi-rigid flame-retardant polyurethane foam having excellent carbonization performance according to (3) or (4), which does not contain red phosphorus and/or organic phosphinate.
(6) A rigid flame-retardant polyurethane foam containing the flame retardant composition for polyurethane foam according to (1) or (2), which has excellent carbonization properties and is characterized in that, when heated at a radiant heat intensity of 50 kW/ ^m2 in a cone calorimeter test according to ISO-5660, the total heat release amount after 5 minutes is 10 MJ/ ^m2 or less and the maximum heat release rate does not exceed 200 kW/ ^m2 for more than 10 seconds.

(7) The rigid flame-retardant polyurethane foam having excellent carbonization performance according to (6), characterized in that when heated at a radiant heat intensity of 50 kW/ ^m² in a cone calorimeter test according to ISO-5660, the total heat release amount after 20 minutes is 8 MJ/ ^m² or less.
(8) The rigid flame-retardant polyurethane foam having excellent carbonization performance according to (6), characterized in that the flame retardant composition for polyurethane foam contains a phosphorus compound represented by formula (1) and a non-halogenated phosphate ester and/or a halogenated phosphate ester as a combined flame retardant, and the combined flame retardant is contained in an amount of 0 to 600 parts by weight per 100 parts by weight of the phosphorus compound represented by formula (1).
(9) The rigid flame-retardant polyurethane foam having excellent carbonization performance according to (8), characterized in that the flame retardant composition for polyurethane foam further contains zinc borate as a concomitant flame retardant.
(10) A rigid flame-retardant polyurethane foam having excellent carbonization performance according to any one of (6) to (9), characterized in that it does not contain red phosphorus and/or organic phosphinate.
(11) The rigid flame-retardant polyurethane foam according to any one of (6) to (10), characterized in that the rigid flame-retardant polyurethane foam is formed by spray foaming.
The gist of this paper is as follows.

The flame retardant composition for polyurethane foam of the present invention easily forms a carbonized layer without melting or dripping during combustion, and exhibits high flame retardancy without the use of red phosphorus. It is also possible to provide a flame retardant composition for polyurethane foam, as well as a flame-retardant polyurethane foam containing this flame retardant composition.

In particular, the flame retardant composition for polyurethane foams of the present invention has excellent carbonization properties during combustion, does not melt or drip, and can provide flexible or semi-rigid flame-retardant polyurethane foams that comply with the flame retardancy standard UL-94 V-0. Furthermore, the present invention can provide rigid flame-retardant polyurethane foams that satisfy the following performance requirements when heated at a radiant heat intensity of 50 kW/ ^m2 in a cone calorimeter test according to ISO-5660: a total heat release amount of 10 MJ/ ^m2 or less after 5 minutes, and a maximum heat release rate of no more than 200 kW/ ^m2 in more than 10 seconds.
Furthermore, when the phosphorus compound represented by formula (1) of the present invention is added to a polyurethane foam, the maximum heat release rate during heating, which is specific to polyurethane foam, can be reduced, and the total heat release amount, shrinkage amount, and weight loss rate can be reduced, compared to when an organic phosphinate such as organic aluminum phosphinate is added to the polyurethane foam.

Hereinafter, embodiments of the flame-retardant polyurethane foam of the present invention will be described.
[Flame retardant (formula (1) below)]
The flame retardant used in the present invention is a compound represented by the following formula (1):
(In the formula, M is Mg, Al, Ca, Ti or Zn, and m is 2, 3 or 4.)

As M in the above formula (1), Al is preferred.
Specific examples of the flame retardant represented by the formula (1) include zinc phosphinate, aluminum phosphinate, magnesium phosphinate, calcium phosphinate, and the like.
These phosphorus compounds represented by formula (1) are usually colorless or white powders, and therefore can be used without impairing the colorability of the product. Among these, aluminum salts in particular have excellent flame retardancy and carbonization properties.

The phosphorus compound represented by formula (1) above can be obtained by heating and reacting, in aqueous solution, either phosphinic acid or an alkali metal salt of phosphinic acid with either water-soluble aluminum, zinc, magnesium, or calcium nitrate, sulfate, carbonate, or hydroxide. This is a type of acid-base or salt reaction in aqueous solution, and is advantageous in that the reaction proceeds quickly and the desired compound is produced in a relatively short time of 1 to 3 hours.

In addition to the phosphorus compound of formula (1), the flame retardant composition of the present invention may also contain one or more additional flame retardants to further improve flame retardancy. Specific examples of the additional flame retardants include melamine phosphate, melamine pyrophosphate, melamine polyphosphate, melamine phthalate, melamine, melamine cyanurate, ammonium polyphosphate, ammonium phosphate, zinc phosphate, non-halogenated phosphate esters, halogenated phosphate esters, bromine-based compounds, barium borate, borax, zinc borate, zinc stannate, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, antimony trioxide, antimony pentoxide, calcium molybdate, zinc molybdate, magnesium molybdate, magnesium silicate, hydrated gypsum, kaolin clay, mica, calcium carbonate, alumite, basic magnesium carbonate, wollastonite, and a zeolite-structured clathrate compound of zinc hydrogen phosphate and ethylenediamine.
The amount of these additional flame retardants to be added is 0 to 600 parts by weight per 100 parts by weight of the phosphorus compound represented by formula (1).
However, it is preferable to use only a non-halogenated phosphate ester and/or a halogenated phosphate ester as a flame retardant for rigid polyurethane foams, or to use a combination of a non-halogenated phosphate ester and/or a halogenated phosphate ester with another flame retardant.
When a combination of a non-halogenated phosphate ester and/or a halogenated phosphate ester with another concomitant flame retardant is employed, the amount of the other concomitant flame retardant is preferably 3 to 100 parts by weight, more preferably 5 to 90 parts by weight, and even more preferably 15 to 75 parts by weight, per 100 parts by weight of the phosphorus compound represented by formula (1).
Examples of the non-halogenated phosphate ester, halogenated phosphate ester and bromine-based compound used as the combined flame retardant are as follows:
The flame retardant composition of the present invention does not contain red phosphorus and/or organic phosphinate. Here, "not containing" means that the composition does not contain an amount sufficient to exert a flame retardant effect, or does not contain any of the above.

Non-halogenated phosphate esters such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, tri(2-ethylhexyl) phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris(isopropylphenyl) phosphate, tris(phenylphenyl) phosphate, trinaphthyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, resorcinol bis(diphenyl) phosphate, bisphenol A bis(diphenyl) phosphate, and bisphenol A bis(dicresyl) phosphate.
Halogenated phosphate esters
Tris(chloroethyl)phosphate, tris(β-chloropropyl)phosphate, tris(dichloropropyl)phosphate, tetrakis(2-chloroethyl)dichloroisopentyl diphosphate, polyoxyalkylene bis(dichloroalkyl)phosphate, poly[oxy[(2-chloro-1-methylethoxy)phosphinylidene]oxy-1,2-ethanediyloxy-1,2-ethanediyl], α-(2-chloro-1-methylethyl)-ω-[[bis(2-chloro-1-methylethoxy)phosphinyl]oxy], and the like.
Bromine compounds
Hexabromobenzene, pentabromotoluene, decabromodiphenylethane, tetrabromobisphenol A, dibromoneopentyl glycol, tribromoneopentyl alcohol, trisdibromoneopentyl phosphate, and the like.

Among the combinations of the phosphorus compound of formula (1) and the combined flame retardant, it is preferred that the phosphorus compound is an aluminum salt, and the combined flame retardant is one or more combined flame retardants selected from the group consisting of melamine, melamine cyanurate, melamine phosphate, melamine polyphosphate, diammonium hydrogen phosphate, ammonium polyphosphate, magnesium hydroxide, aluminum hydroxide, zinc borate, zinc stannate, antimony trioxide, antimony pentoxide, non-halogenated phosphate esters, halogenated phosphate esters, decabromodiphenylethane, trisdibromoneopentyl phosphate, wollastonite, and zeolite-structured clathrate compounds of zinc hydrogen phosphate and ethylenediamine.
Among these combined flame retardants, it is more preferable to use one or more combined flame retardants selected from the group consisting of melamine, melamine cyanurate, melamine phosphate, zinc borate, magnesium hydroxide, aluminum hydroxide, antimony trioxide, non-halogenated phosphate esters, halogenated phosphate esters, decabromodiphenylethane, and zeolite-structured clathrate compounds of zinc hydrogen phosphate and ethylenediamine.
The blending ratio of the phosphorus compound of formula (1) and the combined flame retardant is preferably 0 to 600 parts by weight, more preferably 0 to 400 parts by weight, in total of at least one compound of the combined flame retardant, per 100 parts by weight of the phosphorus compound of formula (1) of the present invention.

The amount of flame retardant composition added to the polyurethane foam of the present invention is in the range of 2 to 200 parts by weight per 100 parts by weight of polyol, with the range of 10 to 150 parts by weight being preferred. Addition of more than 200 parts by weight may inhibit the foaming properties of the polyurethane foam, while addition of less than 2 parts by weight may result in insufficient flame retardancy.

[Flame-retardant polyurethane foam]
The flame-retardant polyurethane foam of the present invention is produced by foaming a polyurethane foam formulation containing polyol, isocyanate, catalyst, blowing agent, and flame retardant as essential raw materials, and optionally further containing a crosslinking agent, foam stabilizer, and other additives. Each component will be described below.

[Flame retardant composition]
The flame retardant composition used in the present invention contains the phosphorus compound of formula (1) as an essential component, and may further contain a concomitant flame retardant, if necessary. When a concomitant flame retardant is added, the blending ratio of each is 0 to 600 parts by weight of the concomitant flame retardant per 100 parts by weight of the phosphorus compound of formula (1).
Furthermore, as the phosphorus compound of formula (1), a salt of Mg, Al, Ca, Ti, or Zn can be used, and as the concomitant flame retardant, one or more selected from the group consisting of melamine phosphate, melamine pyrophosphate, melamine polyphosphate, melamine phthalate, melamine, melamine cyanurate, ammonium polyphosphate, ammonium phosphate, zinc phosphate, non-halogenated phosphate esters, halogenated phosphate esters, bromine-based compounds, barium borate, borax, zinc borate, zinc stannate, magnesium hydroxide, aluminum hydroxide, antimony trioxide, antimony pentoxide, calcium molybdate, zinc molybdate, magnesium molybdate, magnesium silicate, hydrated gypsum, kaolin clay, mica, calcium carbonate, alum, basic magnesium carbonate, calcium hydroxide, wollastonite, and a zeolite-structured clathrate compound of zinc hydrogen phosphate and ethylenediamine can be used.

The most favorable flame retardant performance is exhibited when the phosphorus compound of formula (1) is combined with an aluminum salt as the phosphorus compound of formula (1) and the combined flame retardant is one or more selected from the group consisting of melamine, melamine cyanurate, melamine phosphate, melamine polyphosphate, diammonium hydrogen phosphate, ammonium polyphosphate, magnesium hydroxide, aluminum hydroxide, zinc borate, zinc stannate, antimony trioxide, antimony pentoxide, non-halogenated phosphate esters, halogenated phosphate esters, decabromodiphenylethane, trisdibromoneopentyl phosphate, wollastonite, and zeolite-structured clathrate compounds of zinc hydrogen phosphate and ethylenediamine.

Furthermore, for flexible or semi-rigid flame-retardant urethane foams, the phosphorus compound of formula (1) alone exhibits excellent flame-retardant performance, and further, when used in combination with melamine, melamine cyanurate, melamine polyphosphate, ammonium polyphosphate, or zinc borate as a concomitant flame retardant, favorable flame-retardant performance is also exhibited.
For rigid flame-retardant urethane foams, a combination of the phosphorus compound of formula (1) with a non-halogenated phosphate ester and/or a halogenated phosphate ester as a combined flame retardant exhibits favorable flame retardant performance, and a combination of a non-halogenated phosphate ester and/or a halogenated phosphate ester with zinc borate as another flame retardant also exhibits favorable flame retardant performance.

[Polyol]
The polyol used in the present invention is not particularly limited, and any of the polyols typically used as raw material polyols for polyurethane foams, such as polyether polyols, polyester polyols, and phenolic polyols, can be suitably used. A polyester polyol can be used alone, or a polyester polyol and a polyether polyol can be used in combination. Examples of the polyester polyol include a polyhydric alcohol-polycarboxylic acid condensation polyester polyol and a cyclic ester ring-opening polymer polyester polyol. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediol, hexanediol, trimethylolpropane, and methylpropanediol. Examples of the carboxylic acid include succinic acid, adipic acid, sebacic acid, maleic acid, phthalic anhydride, isophthalic acid, and terephthalic acid. Examples of the ring-opening polyester polyol include a polyester polyol obtained by ring-opening addition polymerization of ε-caprolactone with a glycol.

[Isocyanate]
The isocyanate used in the present invention may be a compound having at least two isocyanate groups, and may include, but is not limited to, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), triphenyl diisocyanate, polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, etc.

[catalyst]
The catalyst may be any known catalyst for polyurethane foams. Examples include amine catalysts such as triethylamine, triethylenediamine, diethanolamine, dimethylaminomorpholine, N-ethylmorpholine, N,N-dimethylcyclohexylamine, and tetramethylguanidine; tin catalysts such as stannous octoate and dibutyltin dilaurate; nitrogen-containing aromatic compounds such as tris(dimethylaminomethyl)phenol, 2,4-bis(dimethylaminomethyl)phenol, and 2,4,6-tris(dialkylaminoalkyl)hexahydro-S-triazine; alkali metal salts of carboxylic acids such as potassium acetate, potassium 2-ethylhexanoate, and potassium octoate; tertiary ammonium salts such as trimethylammonium salt, triethylammonium salt, and triphenylammonium salt; and quaternary ammonium salts such as tetramethylammonium salt, tetraethylammonium, and tetraphenylammonium salt. These catalysts can be used alone or in combination. The amount of catalyst used is preferably 0.1 to 10 parts by weight per 100 parts by weight of polyol.

[Foaming agent]
Examples of blowing agents that can be used include organic physical blowing agents such as low-boiling hydrocarbons (e.g., water, propane, butane, etc.), chlorinated aliphatic hydrocarbon compounds (e.g., dichloroethane, butyl chloride, etc.), fluorine compounds (e.g., hydrofluoroolefins (HFOs) (e.g., trichloromonofluoromethane, trichlorotrifluoroethane, trans-1-chloro-3,3,3-trifluoropropene, etc.), hydrochlorofluorocarbon compounds (e.g., dichloromonofluoroethane, chlorodifluoromethane, 1-chloro-1,1-difluoroethane, etc.), hydrofluorocarbon compounds (e.g., 1,1,1,3,3-pentafluoropropane, 1,1,1,3,3-pentafluorobutane, etc.), ether compounds (e.g., diisopropyl ether, etc.), and mixtures of these compounds. These blowing agents can be used alone or in combination. The amount of these blowing agents used is preferably 1 to 40 parts by weight per 100 parts by weight of polyol.

[Other additives]
The resin composition for polyurethane foam of the present invention may contain, as necessary, various components other than the polyol component, polyisocyanate component, flame retardant, concomitant flame retardant, catalyst, and blowing agent, such as a foam stabilizer, crosslinking agent, foaming aid, dehydrating agent, plasticizer, weathering agent, colorant, and filler, in amounts that do not impair the effects of the present invention. These various components may be added to the polyol component or polyisocyanate component in advance, or they may be added when the polyol component and polyisocyanate component are mixed.

Examples of the foam stabilizer include commercially available foam stabilizers used in the production of polyurethane foam. While not particularly limited, examples of foam stabilizers include surfactants, such as organic silicone surfactants, including nonionic surfactants such as organosiloxane-polyoxyalkylene copolymers and silicone-grease copolymers. The amount of the silicone compound foam stabilizer is preferably 0.5 parts by weight or more per 100 parts by weight of the polyol.

[Production of flame-retardant polyurethane foam]
The method for producing the polyurethane foam containing the flame retardant composition of the present invention is not particularly limited, and it can be produced by a conventional method.
Specifically, the polyurethane foam can be produced by a known foaming method in which polyurethane foam raw materials containing the polyol, isocyanate, catalyst, blowing agent, foam stabilizer, and flame retardant are stirred, mixed, and reacted.

There are two foaming methods: slab foaming and mold foaming, and either molding method is acceptable. Slab foaming is a method in which mixed polyurethane foam raw materials are discharged onto a belt conveyor and foamed at atmospheric pressure and room temperature (20±15°C). Mold foaming, on the other hand, is a method in which mixed foam raw materials are filled into a mold (forming tool) and foamed within the mold. These foaming methods are used to produce what are known as flexible or semi-rigid polyurethane foams.

Another foaming method is the in-situ foaming method. Foamed-in-situ polyurethane foam is what's known as rigid polyurethane foam, produced by mechanically or manually foaming a polyurethane foam resin composition at the molding site. This method also employs spray foaming, specifically, a polyurethane foam molding method in which the polyurethane foam resin composition is sprayed in mist form from a foaming machine and sprayed directly onto the target object, simultaneously foaming and adhering the polyurethane foam to the target object.

In in-situ spray foaming, it is difficult to control the temperature, so the resin composition for polyurethane foam used is preferably one that has low viscosity and is easy to handle even at room temperature (20±15°C), and this method is a production method for what is generally called rigid polyurethane foam.
The density of the flame-retardant polyurethane foam of the present invention is preferably 30 to 120 kg/ ^m3 , more preferably 40 to 90 kg/ ^m3 , for rigid flame-retardant polyurethane foams, and is preferably 10 to 70 kg/ ^m3 , more preferably 20 to 60 kg/ ^m3 , for flexible and semi-rigid flame-retardant polyurethane foams.

The flame retardant composition of the present invention can be used in rigid, semi-rigid, and flexible polyurethane foams, and the uses of the resulting flame-retardant polyurethane foam are not limited to automotive sound-absorbing, sound-proofing, and vibration-proofing materials and building insulation materials. It can also be used, for example, in seat cushions, floor carpets, ceiling materials, engine filters, oil filters, insulators, furniture cushioning materials, electrical components (for filling gaps in wiring cable boxes, piping penetrations, etc.), packaging materials, and cushioning materials used as insulation or interior materials for vehicles, railways, aircraft, and ships.

The present invention will be explained in more detail below using examples and comparative examples, but the technical scope of the present invention is not limited to the following examples. In the following examples, unless otherwise specified, "%" refers to % by weight and "parts" refers to parts by weight. Each flame-retardant polyurethane foam was evaluated using the following methods.

[Evaluation of flame retardancy, etc.]
(Sample Preparation)
Rigid and flexible polyurethane foams were produced by the following method and subjected to tests for flame retardancy and the like.
Rigid polyurethane foam sample preparation method
The polyol compound, foam stabilizer, amine catalyst, and polymerization catalyst were weighed into a 1000 mL polypropylene beaker and stirred at 20° C. for 30 seconds with a stirrer.
The flame retardant component was added to the stirred mixture and mixed with a mixer. Next, water and a blowing agent such as HFO were added and mixed. Finally, an organic isocyanate (Cosmonate M-200) was added and stirred vigorously for about 10 seconds to produce a foam with a density of 60 kg/ ^m3 .
Flexible polyurethane foam sample preparation method
The polyol compound, water as a blowing agent, catalyst, foam stabilizer, and other additives as required were placed in a 1000 mL polypropylene beaker and stirred at 25° C. for 30 seconds with a stirrer.
The flame retardant component was added to the stirred mixture and mixed with a mixer. Finally, an organic isocyanate (Millionate MR-200) was added and the mixture was stirred vigorously for about 10 seconds to prepare a foam with a density of 29 kg/ ^m3 .

(Evaluation method)
Rigid polyurethane foam
Cone Calorimeter Test
A 10 cm x 10 cm x 5 cm sample for cone calorimeter testing was cut out from the rigid polyurethane foam prepared by the above method, and in accordance with ISO-5660, the total heat release, the time over 200 kW/ ^m2 , and the maximum heat release rate were measured when heated for 5 minutes, 10 minutes, and 20 minutes at a radiant heat intensity of 50 kW/ ^m2 .
This measurement method is a test method defined by the General Building Research Institute, a public organization defined in Article 108-2 of the Enforcement Order of the Building Standards Act, as a method corresponding to the standards based on the cone calorimeter method.

(Measurement of density)
The dimensions of the cone calorimeter test sample were measured using a vernier caliper, and the mass was measured using an electronic balance, and the density was calculated from the measured values.

(Evaluation of Residue State)
In the sample after the ISO-5660 test, if cracks or holes penetrating to the back surface were visually observed, the sample was rated as "present", and if no deformation reaching the back surface was observed, the sample was rated as "absent".

(Measurement of shrinkage)
After the ISO-5660 test, the deformation distance from 10 cm in the horizontal direction and from 5 cm in thickness was measured relative to the original dimensions of the sample. Expansion was marked "+", and contraction was marked "-".
This is because if there is a large amount of contraction or expansion when a fire occurs, cracks or peeling from the wall may occur, which may lead to continued combustion, so it is desirable to have as little expansion and contraction as possible.

(weight reduction)
The mass of the sample before and after the ISO-5660 test was measured using an electronic balance, and the weight loss rate was calculated from the obtained measured values.

Soft polyurethane foam
UL-94V test
A test piece measuring 127 mm in length, 12.7 mm in width, and 3.0 mm in thickness was prepared from the flexible polyurethane foam prepared by the above method, and a vertical combustion test was carried out in accordance with the UL-94V standard.
V-0 is the highest rating, with flame retardancy decreasing as the rating goes to V-1 and V-2. However, materials that did not fall into any of the V-0 to V-2 ratings were rated as NC.

(Evaluation results)
Regarding the flame retardancy test of the rigid polyurethane foam, the evaluation results of the examples and comparative examples are shown in Tables 1 and 2.
Furthermore, the criteria for the evaluation results in Table 2 based on the above-mentioned cone calorimeter test are as follows:
Non-flammable: Total heat generation after 20 minutes of heating is 8.0 MJ/ ^m² or less. Semi-non-flammable: Total heat generation after 10 minutes of heating is 8.0 MJ/m² or ^less . Flame retardant: Total heat generation after 5 minutes of heating is 8.0 MJ/ ^m² or less.

Polyester polyol: Actocol ES-258N (Mitsui Chemicals SKC Polyurethanes Co., Ltd.)
Polyether polyol: Actocol T-700S (Mitsui Chemicals SKC Polyurethanes Co., Ltd.)
Phthalic acid polyol: Maximol RFK-505 (Kawasaki Chemical Industries, Ltd.)
Silicone foam stabilizer: NIAX L-6620 (MOMENTIVE)
Amine catalyst: N,N-dimethylcyclohexylamine polymerisation catalyst (13%); potassium octylate
TMCPP: Tris(β-chloropropyl)phosphate (Daihachi Chemical Industry Co., Ltd.)
Polyoxyalkylene bis(dichloroalkyl)phosphate; CR-504L (Daihachi Chemical Industry Co., Ltd.)
Tris(dichloropropyl)phosphate; Tris(dichloropropyl)phosphate (Tokyo Chemical Industry Co., Ltd.)
Cresyl diphenyl phosphate; CDP (Daihachi Chemical Industry Co., Ltd.)
Resorcinol bis(diphenyl)phosphate; CR-733S (Daihachi Chemical Industry Co., Ltd.)
Zinc borate: ZB2335 (Kinseimatec Co., Ltd.)
Zinc stannate; ZHS (Kinseimatec Co., Ltd.)
Magnesium hydroxide: Kisuma 5A (Kyowa Chemical Industry Co., Ltd.)
Aluminum hydroxide: Hijilite H-32 (Showa Denko K.K.)
Zinc molybdate; Zinc molybdate (Kojundo Chemical Laboratory Co., Ltd.)
Melamine phosphate; BUDIT310 (CBC Co., Ltd.)
Melamine polyphosphate; BUDIT3141 (CBC Corporation)
Diammonium phosphate; Diammonium hydrogen phosphate (Taihei Chemical Industry Co., Ltd.)
Ammonium polyphosphate: FR CROS484 (CBC Co., Ltd.)
Aluminum tris(diethylphosphinate) (organoaluminum phosphinate); EXOLIT OP930 (Clariant Chemicals)
Decabromodiphenylethane: SAYTEX8010 (Albemarle Japan Co., Ltd.)
Trisdibromoneopentyl phosphate; CR-900 (Daihachi Chemical Industry Co., Ltd.)
Antimony trioxide; Antimony trioxide (Suzuhiro Chemical Co., Ltd.)
Antimony pentoxide: BurnEx 30-107 (NYACOL Nano Technologies, Inc.)
Wollastonite: SH-400 (Kinseimatec Co., Ltd.)
Zinc hydrogen phosphate: Firecut ZPO-3 (Suzuhiro Chemical Co., Ltd.) Zeolite-structured zinc hydrogen phosphate clathrate compound with ethylenediamine Red phosphorus: Nova Excel 140 (Rinkagaku Sangyo Co., Ltd.)
HFO: HFO-1233zdE (Honeywell Japan, Ltd.)
Polymethylene polyphenyl polyisocyanate: Cosmonate M-200 (Mitsui Chemicals SKC Polyurethanes Co., Ltd.)

Note that the index in Tables 1-1 and 1-2 is defined as (equivalents of polyisocyanate) ÷ (equivalents of polyol + equivalents of water). Here, the equivalents of the polyol compound are expressed as [hydroxyl value of polyol compound (mg KOH/g)] × [weight of polyol compound (g)] ÷ [molecular weight of potassium hydroxide]. Furthermore, the equivalents of the polyisocyanate are expressed as [molecular weight of polyisocyanate group] × 100 ÷ [weight % of isocyanate group], and the equivalents of water are expressed as [weight of water (g)] × 2 ÷ [molecular weight of water].

The evaluation results for the flame retardancy test of flexible polyurethane foam for the Examples and Comparative Examples are shown in Table 3.

Polyether polyol: Sannix GP-3000V (Sanyo Chemical Industries, Ltd.)
Triethylenediamine dipropylene glycol solution: TEDA-L33 (Tosoh Corporation)
Stannous octoate; MRH-110 (Johoku Chemical Industry Co., Ltd.)
Silicone foam stabilizer: L-540 (Dow Corning Toray Co., Ltd.)
Melamine cyanurate: STABIACE MC-2010N (Sakai Chemical Industry Co., Ltd.)
Melamine (Mitsui Chemicals, Inc.)
Melamine polyphosphate; BUDIT3141 (CBC Corporation)
Ammonium polyphosphate: FR CROS484 (CBC Co., Ltd.)
Zinc borate: ZB2335 (Kinseimatec Co., Ltd.)
TMCPP: Tris(β-chloropropyl)phosphate (Daihachi Chemical Industry Co., Ltd.)
Polymeric MDI (Tosoh Corporation)

As can be seen from Tables 1-1 and 1-2, the flame-retardant polyurethane foams using the flame retardant of the present invention had high flame retardancy and a low maximum heat release rate equivalent to or higher than those using red phosphorus flame retardants, while also exhibiting a low total heat release value at 5 minutes and maintaining good physical properties as foams.
According to the results shown in Table 2, when the flame retardant of the present invention was used for polyurethane foam, the density was lower than when organic aluminum phosphinate was used, the total heat release amount, maximum heat release rate and weight loss rate at 5 minutes, 10 minutes and 20 minutes were all lower, the shrinkage and weight loss rate in the transverse and thickness directions of the polyurethane foam after the test were small, and the polyurethane foam was non-flammable.
Furthermore, the results in Table 3 show that when the composition of the present invention is used in a flexible polyurethane foam, high flame retardancy can be achieved even at a lower density.

Claims (7)

A flame retardant composition for polyurethane foams, comprising a polyol compound including a polyester-based polyol and a polymerization catalyst,
A phosphorus compound represented by the following formula (1):
and one or more selected from tris(β-chloropropyl)phosphate, polyoxyalkylene bis(dichloroalkyl)phosphate, and tris(dichloropropyl)phosphate , and the following other combined flame retardants are contained in a total amount of 15 to 600 parts by weight per 100 parts by weight of the phosphorus compound represented by the following formula (1),
Furthermore, one or more other flame retardants selected from the group consisting of melamine phosphate, melamine cyanurate, zinc borate, zinc stannate, magnesium hydroxide, aluminum hydroxide, antimony trioxide, antimony pentoxide, and a zeolite-structured zinc hydrogen phosphate and ethylenediamine clathrate compound,
A flame retardant composition for polyurethane foams for obtaining a rigid flame-retardant polyurethane foam, which contains 15 to 75 parts by weight per 100 parts by weight of a phosphorus compound represented by the following formula (1 ⁾ , and which satisfies the performance of having a total heat release amount of 10 MJ/ ^m2 or less after 5 minutes and a maximum heat release rate of not more than 200 kW/ ^m2 in more than 10 seconds when heated at a radiant heat intensity of 50 kW/m2 in a cone calorimeter test according to ISO-5660:
(In the formula, M is Mg, Al, Ca, Ti, or Zn, and m is 2, 3, or 4.)
However, this does not include cases where a composite flame retardant of aerogel powder and a phosphate ester flame retardant is contained, cases where clay is contained, and cases where expandable graphite is contained. the phosphorus compound represented by formula (1) is a salt of Al,
2. The flame retardant composition for polyurethane foam according to claim 1 , wherein the other concomitant flame retardant is one or more flame retardants selected from the group consisting of melamine cyanurate , melamine phosphate, magnesium hydroxide, aluminum hydroxide, zinc borate, zinc stannate, antimony trioxide, antimony pentoxide , and a zeolite-structured clathrate compound of zinc hydrogen phosphate and ethylenediamine. A phosphorus compound represented by the following formula (1):
(In the formula, M is Mg, Al, Ca, Ti, or Zn, and m is 2, 3, or 4.)
and one or more selected from tris(β-chloropropyl)phosphate, polyoxyalkylene bis(dichloroalkyl)phosphate, and tris(dichloropropyl)phosphate, and the following other combined flame retardants are contained in a total amount of 15 to 600 parts by weight per 100 parts by weight of the phosphorus compound represented by the above formula (1),
Furthermore, one or more other flame retardants selected from the group consisting of melamine phosphate, melamine cyanurate, zinc borate, zinc stannate, magnesium hydroxide, aluminum hydroxide, antimony trioxide, antimony pentoxide, and a zeolite-structured zinc hydrogen phosphate and ethylenediamine clathrate compound,
A rigid flame-retardant polyurethane foam produced by blending a flame retardant composition for polyurethane foam containing a polyol compound including a polyester polyol, in which the polyol compound contains 15 to 75 parts by weight per 100 parts by weight of the phosphorus compound represented by formula (1), and a polymerization catalyst,
A rigid flame-retardant polyurethane ^foam with excellent carbonization performance, characterized by satisfying the following performance characteristics: when heated at a radiant heat intensity of 50 kW/m2 in an ISO-5660 cone calorimeter test, ^the total heat release amount after 5 minutes is 10 MJ/m2 or less, and the maximum heat release rate does not exceed 200 kW/m2 in more than 10 ^seconds .
However, this does not include the cases where the flame retardant composition for polyurethane foam contains a composite flame retardant of the above-mentioned aerogel powder and a phosphate ester-based flame retardant, where clay is contained, or where expandable graphite is contained. 4. The rigid flame-retardant polyurethane foam with excellent carbonization performance according to claim 3, wherein the total heat generated after 20 minutes of heating is 8 MJ/ ^m2 or less when heated at a radiant heat intensity of 50 kW/ ^m2 in a cone calorimeter test according to ISO-5660. 5. The rigid flame-retardant polyurethane foam having excellent carbonization resistance according to claim 3, wherein the flame retardant composition for polyurethane foam further contains zinc borate as another concomitant flame retardant. 6. The rigid flame-retardant polyurethane foam having excellent carbonization properties according to any one of claims 3 to 5, which does not contain red phosphorus and/or organic phosphinate. 7. The rigid flame-retardant polyurethane foam having excellent carbonization resistance according to claim 3, wherein the rigid flame-retardant polyurethane foam is formed by spray foaming.