JP5555121B2 - Flame retardant polyurethane foam and method for producing the same - Google Patents

Description

  The present invention relates to a flame retardant polyurethane foam obtained by reacting and foaming a mixed raw material containing polyols and polyisocyanates by a mechanical floss method, and a method for producing the same.

  In general, as a foaming method for producing a polyurethane foam by reacting and foaming a mixed raw material containing polyols and polyisocyanates, either a chemical foaming method or a mechanical froth method is used. In the chemical foaming method, a chemical foaming agent that reacts with isocyanate to generate gas and a physical foaming agent that vaporizes with reaction heat during foam molding are added to the mixed raw material, and bubbles are formed by these foaming agents. It is a method to make it. On the other hand, the mechanical floss method is a method in which bubbles are formed by mixing a compressed gas such as an inert gas when the mixed raw material is stirred and mixed without adding a specific foaming agent to the mixed raw material. is there.

  Compared with the chemical foaming method, when the mechanical floss method is adopted, the foaming pressure at the time of foaming is low, so that a very high density polyurethane foam can be obtained. Taking advantage of these features, polyurethane foam obtained by mechanical flossing is suitably used as a cushioning material for vibration and shock buffering in electronic device parts such as mobile phones, cameras, and televisions, and as a sealing material for dust prevention. ing. Moreover, since it is excellent in the non-migration | transfer property and friction stability of a containing component, it may be used as a foot rubber.

  By the way, a flame retardant such as a halogen flame retardant and an organic phosphorus flame retardant is added to such polyurethane foam for the purpose of imparting flame retardancy. Among these flame retardants, halogen-based flame retardants are often used because of their excellent flame-retardant action. However, halogen-based flame retardants have a large impact on the environment, so use them as much as possible. There is a demand to avoid. For example, at the International Electrotechnical Commission (IEC), the Japan Electronic Circuits Association (JPCA), and the American Electronic Circuits Association (IPC), a bromine content of 900 ppm or less, a chlorine content of 900 ppm or less, and bromine and chlorine A threshold value such as a total content of 1500 ppm or less is provided.

  Therefore, in recent years, attempts have been made to impart flame retardancy to polyurethane foams by blending polyols without using flame retardants. For example, Patent Document 1 discloses a technique for imparting flame retardancy to a polyurethane foam by using together a polyether polyol and a specific polymer polyol as polyols.

JP 2006-111788 A

  However, the technology of Patent Document 1 is a technology related to a polyurethane foam obtained by foaming by a chemical foaming method using a foaming agent such as water, and a technology related to a polyurethane foam obtained by foaming by a mechanical floss method. Absent. Therefore, in the polyurethane foam obtained by foaming by the mechanical floss method, the combination of polyether polyol and polymer polyol as polyols was tried, but although some flame retardant improvement effect can be obtained, tensile strength There is a problem that strength such as tear strength is reduced and distortion is likely to occur during heat compression.

  The present invention has been made in view of such conventional circumstances, and an object of the present invention is to provide a polyurethane foam obtained by reacting and foaming a mixed raw material containing polyols and polyisocyanates by a mechanical froth method. Another object of the present invention is to provide a flame retardant polyurethane foam excellent in strength such as tensile strength and tear strength, and low compression residual strain, and a method for producing the same, while improving flame retardancy by blending types.

  In order to achieve the above-mentioned object, the flame-retardant polyurethane foam according to claim 1 is obtained by reacting a mixed raw material containing polyols and polyisocyanates with a reaction and foaming by a mechanical froth method. A first polyol composed of a polymer polyol having a number average molecular weight of 1500 to 4500 and a functional group number of 3 as the polyols, and 50 to 80 parts by mass with respect to 100 parts by mass of the polyols as a whole, (B) a second polyol composed of a polyether polyol having a number average molecular weight of 300 to 900 and a functional group of 3 is composed of 5 to 16 parts by mass with respect to 100 parts by mass of the whole polyol, and (C) a functional group having 2 or 3 functional groups. The third polyol made of polyester polyol is 1 to 6 masses based on 100 mass parts of the whole polyols. Characterized in that it contains and.

  The flame-retardant polyurethane foam according to claim 2 contains, in the invention according to claim 1, monomerisocyanate, carbodiimide-modified isocyanate, or a prepolymer obtained using them as a starting material as the polyisocyanate. It is characterized by that.

  The flame-retardant polyurethane foam according to claim 3 is the invention according to claim 1 or 2, wherein the (C) third polyol is a caprolactone-based polyester polyol having 3 functional groups. And

  The method for producing a flame-retardant polyurethane foam according to claim 4 is a method for producing a flame-retardant polyurethane foam in which a mixed raw material containing polyols and polyisocyanates is reacted and foamed by a mechanical floss method. As the polyols, (A) a first polyol composed of a polymer polyol having a number average molecular weight of 1500 to 4500 and a functional group number of 3 is 50 to 80 parts by mass with 100 parts by mass of the whole polyols, and (B) number A second polyol composed of a polyether polyol having an average molecular weight of 300 to 900 and a functional group number of 3 is composed of 5 to 16 parts by mass with respect to 100 parts by mass of the polyol as a whole, and (C) a polyester polyol having 2 or 3 functional groups. The third polyol is 1 to 6 parts by mass based on 100 parts by mass of the whole polyol. Which comprises using.

  According to the flame retardant polyurethane foam of the present invention and the method for producing the same, it is possible to improve the strength such as tensile strength and tear strength while improving the flame retardancy and to obtain low compression residual strain. .

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described in detail.
The flame retardant polyurethane foam of this embodiment is obtained by foaming a mixed raw material containing polyols and polyisocyanates by reaction and mechanical flossing. The mechanical froth method is a method of forming bubbles by mixing a compressed gas such as an inert gas when stirring and mixing the mixed raw material without adding a specific foaming agent to the mixed raw material. .

First, each component contained in the mixed raw material will be described.
[Polyols]
As the polyols, at least (A) a first polyol composed of a polymer polyol, (B) a second polyol composed of a polyether polyol, and (C) a third polyol composed of a polyester polyol are combined. Used.

  (A) The first polyol is a polymer polyol having a number average molecular weight of 1500 to 4500 (preferably 2000 to 4000) and a functional group number of 3, and (B) the second polyol and (C) the third polyol. Combined use imparts flame retardancy to polyurethane foam. (A) As the first polyol, for example, a polymer polyol obtained by graft copolymerization of vinyl monomers such as acrylonitrile and styrene in a polyether polyol having 3 functional groups as a base polyol can be suitably used. Examples of the base polyol include polyether polyols made of a polymer obtained by addition polymerization of an alkylene oxide such as ethylene oxide or propylene oxide to a trivalent polyhydric alcohol such as glycerin. In addition, the number average molecular weight of said (A) 1st polyol means the number average molecular weight of a base polyol.

  Further, (A) the polymer content of the first polyol (mass ratio of the portion other than the base polyol relative to the whole polymer polyol) is preferably 15 to 45% by mass, and more preferably 20 to 40% by mass. From the viewpoint of improving the strength of the polyurethane foam, it is preferable that the polymer content of (A) the first polyol is large, but if the polymer content exceeds 45% by mass, the viscosity becomes too high and the workability decreases. There is a risk. In addition, as (A) 1st polyol, only 1 type of polymer polyol may contain, and 2 or more types of polymer polyols from which a number average molecular weight, polymer content, etc. differ may be contained in combination.

  The content of the (A) first polyol in the mixed raw material is 50 to 80 parts by mass, preferably 55 to 78 parts by mass, and more preferably 58 to 80 parts by mass when the total polyols are 100 parts by mass. 70 parts by mass. If this content is less than 50 parts by mass, flame retardancy may be reduced. If it exceeds 80 parts by mass, a certain degree of hardness may be obtained, but there is a risk of insufficient strength in terms of tensile strength, tear strength, etc. There is.

  (B) The second polyol is a polyether polyol having a number average molecular weight of 300 to 900 (preferably 450 to 750) and a functional group number of 3, and (A) is combined with the first polyol to form a polyurethane foam. In addition to imparting flame retardancy, (C) the combined use with the third polyol improves the strength such as the tensile strength of the polyurethane foam and the low compression residual strain.

  (B) As the second polyol, for example, a polyether polyol made of a polymer obtained by addition polymerization of an alkylene oxide such as ethylene oxide or propylene oxide to a trivalent polyhydric alcohol such as glycerin can be suitably used. . Moreover, (B) 2nd polyol may have functional groups other than hydroxyl groups, such as an amino group. (B) As the second polyol, only one kind of polyether polyol may be contained, or two or more kinds of polyether polyols having different number average molecular weights or functional groups may be contained in combination. Good.

  The content of the (B) second polyol in the mixed raw material is 5 to 16 parts by mass when the total polyols are 100 parts by mass. When this content is less than 5 parts by mass, there is a possibility that low compression residual strain cannot be obtained sufficiently, and when it exceeds 16 parts by mass, low resilience is developed. From the viewpoint of obtaining a highly repulsive polyurethane foam, the content is preferably 16 parts by mass or less. Moreover, when the said content of (B) 2nd polyol is 7-10 mass parts, high resilience can be provided to a polyurethane foam.

  (C) The third polyol is a polyester polyol having 2 or 3 functional groups, and (A) imparts flame retardancy to the polyurethane foam in combination with the first polyol, and (B) the second polyol. The combined use with a polyol improves the tensile strength and low compressive residual strain of the polyurethane foam. In addition, (C) the third polyol also has the effect of miniaturizing and homogenizing the cells of the polyurethane foam.

  (C) The molecular weight (number average molecular weight) of the third polyol is preferably in the range of 400 to 2500, and more preferably in the range of 450 to 1500. (C) As the third polyol, for example, polycaprolactone polyester polyol, adipate polyester polyol, or the like can be used. Examples of polycaprolactone-based polyester polyols include polyester polyols obtained by ring-opening addition polymerization of lactones such as ε-caprolactone. Examples of the adipate polyester polyol include a polyester polyol obtained by polycondensation of a polyfunctional carboxylic acid and a polyfunctional hydroxy compound. Among these polyester polyols, it is preferable to use a polycaprolactone-based polyester polyol having 3 functional groups from the viewpoint of improving flame retardancy and reducing the content of volatile organic compounds.

  The content of the (C) third polyol in the mixed raw material is 1 to 6 parts by mass, preferably 2 to 5 parts by mass, when the total polyols are 100 parts by mass. When this content is less than 1 part by mass, low resilience appears. From the viewpoint of obtaining a highly repellent polyurethane foam, the content is preferably 1 part by mass or more. Moreover, when the said content exceeds 6 mass parts, low compression residual distortion property may be impaired and compression residual distortion may increase.

  Moreover, you may contain other polyols other than the said 1st-3rd polyol as polyols. Any other polyol can be used without particular limitation as long as it is a polyol generally used for polyurethane foams. In addition, although the antioxidant may be mix | blended with the said polyols in order to suppress the oxidation of a component, dibutylhydroxytoluene (BHT) is used as antioxidant from a viewpoint of reduction of a volatile organic compound content. It is preferable to use BHT-free polyols that are not used. Examples of the BHT-free polyols include polyols using hindered phenol antioxidants having a molecular weight of 300 or more.

[Polyisocyanates]
Polyisocyanates are compounds having a plurality of isocyanate groups, such as tolylene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), triphenylmethane triisocyanate, xylylene diene. Aromatic polyisocyanates such as isocyanate (XDI), alicyclic polyisocyanates such as isophorone diisocyanate (IPDI) and dicyclohexylmethane diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate (HDI), or these and polyols Modified polyisocyanates such as free isocyanate prepolymers by reaction and carbodiimide-modified polyisocyanates can be used. Further, these polyisocyanates may be contained alone or in combination of two or more.

  The polyisocyanates are monomeric isocyanate (for example, monomeric MDI), carbodiimide-modified isocyanate, or a prepolymer having an isocyanate group terminal obtained from them as a starting material from the viewpoint of reducing the halogen content (particularly chlorine content). Is preferably used. The number of functional groups of the polyisocyanate is preferably in the range of 2.0 to 2.2.

  In addition, it is preferable that the isocyanate index of polyisocyanates is in the range of 0.9 to 1.1. The isocyanate index is an equivalent ratio of isocyanate groups of polyisocyanates to reactive groups such as hydroxyl groups that can react with isocyanate in polyols. Accordingly, when the value is less than 1, it means that the reactive group such as a hydroxyl group is in excess of the isocyanate group, and when it exceeds 1, it means that the isocyanate group is in excess of the reactive group such as a hydroxyl group. . When the isocyanate index is less than 0.9, there is a possibility that polyols cannot sufficiently react with polyisocyanates. On the other hand, when the isocyanate index exceeds 1.1, there is a possibility that low compression residual distortion and deterioration of low resilience may occur.

[Foam stabilizer]
The foam stabilizer is used for smoothly foaming the mixed raw material, and the mixed raw material preferably contains a foam stabilizer. As the foam stabilizer, a known foam stabilizer that is usually used when the mechanical floss method is employed, for example, a silicone foam stabilizer, can be used. Since such a foam stabilizer has a high viscosity, it is usually blended in the mixed raw material in a state diluted with a solvent such as alkylbenzene.

  Here, from the viewpoint of reducing the content of volatile organic compounds and improving flame retardancy, it is preferable to use a low-viscosity polyol having a viscosity of 500 cps or less (preferably a viscosity of 40 cps to 500 cps) as the solvent. Examples of the low-viscosity polyol include polyether polyols having a molecular weight (number average molecular weight) of 1700 or less, and polyols that are liquid at room temperature. The number of functional groups of the low viscosity polyol is not particularly limited, but is preferably 1 to 3 functional groups. Moreover, what has the name of goods as a crosslinking agent etc. can also be used as said low-viscosity polyol.

  The low-viscosity polyol as a solvent reacts with isocyanates in the reaction raw material and is taken into the polyurethane molecule. Thereby, volatilization of a low-viscosity polyol can be suppressed. In addition, if the viscosity of the said low viscosity polyol is 500 cps or less, a hydroxyl group will react with isocyanates suitably.

  The content of the foam stabilizer in the mixed raw material is preferably 3 to 6 parts by mass with respect to 100 parts by mass of the polyols. When the content is less than 3 parts by mass, the foam regulating power is insufficient, and it may be difficult to form a uniform cell structure or to reduce the density. Moreover, even if it contains exceeding 6 mass parts, the drastic improvement in foam regulating ability beyond this cannot be expected. Moreover, when diluting a foam stabilizer with a solvent, it is preferable to set it as the range of 25: 75-75: 25 by mass ratio (foam stabilizer: solvent).

[catalyst]
The catalyst is mainly for accelerating the urethanization reaction between polyols and polyisocyanates, and the mixed raw material preferably contains a catalyst. As the catalyst, known catalysts usually used for polyurethane foams, for example, tertiary amines such as triethylenediamine, dimethylethanolamine, N, N ′, N′-trimethylaminoethylpiperazine, stannous octoate, octyl Organic metal compounds such as tin oxide (tin octoate), acetates, and alkali metal alcoholates can be used.

  The content of the catalyst in the mixed raw material is preferably 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the polyols. When this content is less than 0.1 parts by mass, the urethanization reaction may not be sufficiently promoted, and when it exceeds 5.0 parts by mass, the urethanization reaction is excessively promoted and the cell structure is increased. Formation tends to be uneven.

[Crosslinking agent]
The crosslinking agent is used for forming a crosslinking between polyols to improve the strength and the like, and the mixed raw material preferably contains a crosslinking agent. As the crosslinking agent, known crosslinking agents usually used for polyurethane foams, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, Polyhydric alcohols such as glycerin, trimethylolpropane, pentaerythritol, sorbitol, amines such as ethylenediamine, diethylenetriamine, hexamethylenediamine, hydrazine, diethyltoluenediamine, diethylenetriamine, amino alcohols such as diethanolamine, triethanolamine, and the like And compounds obtained by adding ethylene oxide, polypropylene oxide, or the like to these active hydrogen compounds.

  The content of the crosslinking agent in the mixed raw material is preferably 2.0 to 10.0 parts by mass with respect to 100 parts by mass of the polyols. When this content is less than 2.0 parts by mass, the strength such as tensile strength may be insufficient. Moreover, when it exceeds 10.0 mass parts, there exists a possibility that hardness may become hard too much or low resilience may be expressed.

[Other ingredients]
The mixed raw material may contain other components other than the above as necessary. Examples of other components include an antioxidant, an ultraviolet absorber, a thickener, a plasticizer, an antibacterial agent, and a colorant. Examples of the antioxidant include dibutylhydroxytoluene and hindered phenol antioxidants. From the viewpoint of reducing the content of volatile organic compounds, a hindered phenol antioxidant having a molecular weight of 300 or more is used. It is particularly preferable to use it. Examples of the thickener include calcium carbonate, aluminum hydroxide, and magnesium hydroxide.

Next, the manufacturing method of the flame-retardant polyurethane foam of this embodiment is demonstrated.
The flame-retardant polyurethane foam of the present embodiment can be produced by a general polyurethane foam production method used when a mechanical floss method is employed. For example, after the mixed raw material is put into a mixing head, the mixture is stirred and mixed so as to be homogeneous while mixing an inert gas. Next, a flame retardant polyurethane foam can be obtained by heat-curing the mixed raw material mixed in the mixing head on a release paper or the like or in a predetermined mold.

  The flame-retardant polyurethane foam obtained in this way becomes a polyurethane foam excellent in tensile strength, tear strength, and low compression residual strain as well as excellent in flame retardancy without using a flame retardant. . The flame-retardant polyurethane foam of the present embodiment can be suitably applied to, for example, a cushioning material for vibration and shock buffering and a dustproof sealing material in electronic device parts such as mobile phones, cameras, and televisions. it can.

Next, operational effects in the present embodiment will be described below.
(1) The flame-retardant polyurethane foam is obtained by foaming a mixed raw material containing polyols and polyisocyanates by reaction and mechanical flossing. As the polyols, (A) a first polyol composed of a polymer polyol having a number average molecular weight of 1500 to 4500 and 3 functional groups, 50 to 80 parts by mass with respect to 100 parts by mass of the whole polyols, and (B) a number average molecular weight 300 to 900, a second polyol composed of a polyether polyol having 3 functional groups, 5 to 16 parts by mass with 100 parts by mass as a whole of the polyols, and (C) a third polyol composed of a polyester polyol having 2 or 3 functional groups The polyol is 1 to 6 parts by mass with 100 parts by mass as a whole of the polyols. According to the above configuration, the flame retardancy of the polyurethane foam can be improved without using a flame retardant, and the polyurethane foam has excellent strength such as tensile strength and tear strength and low compression residual strain. It becomes.

  (2) Preferably, polyisocyanates contain monomeric isocyanate, carbodiimide-modified isocyanate, or a prepolymer obtained using them as starting materials. In this case, the amount of halogen contained in the polyurethane foam can be reduced.

  (3) Preferably, (C) the third polyol is a polycaprolactone-based polyester polyol having 3 functional groups. In this case, the flame retardancy of the polyurethane foam can be further improved, and the volatile organic compound content contained in the polyurethane foam can be reduced.

  In addition, when a polyurethane foam is used for applications such as electronic equipment, a volatile organic compound generated from the polyurethane foam causes a problem of fogging the inner surface of glass or transparent plastic. Therefore, the flame-retardant polyurethane foam having a reduced volatile organic compound content can be used particularly suitably for applications such as electronic equipment.

  (4) Preferably, the content of the (B) second polyol in the mixed raw material contains 7 to 10 parts by mass with 100 parts by mass of the entire polyol. In this case, high resilience can be imparted to the flame retardant polyurethane foam.

  (5) At the time of production of the flame-retardant polyurethane foam, preferably, the foam stabilizer is contained in the mixed raw material in a state diluted with a polyol having a viscosity of 500 cps or less. In this case, the content of volatile organic compounds contained in the polyurethane foam can be reduced.

Next, a technical idea that can be grasped from the above embodiment will be described.
(A) The flame-retardant polyurethane foam according to (B), wherein the second polyol is contained in an amount of 7 to 10 parts by mass based on 100 parts by mass of the whole polyol.

  (B) The method for producing a flame-retardant polyurethane foam according to claim 1, wherein a foam stabilizer is contained in the mixed raw material in a state diluted with a polyol having a viscosity of 500 cps or less.

Next, the embodiment will be described more specifically with reference to examples and comparative examples.
[Production of flame retardant polyurethane foam]
First, the components of the mixed raw materials used in the polyurethane foams of the examples and comparative examples are shown below.

Polymer polyol 1: Polymer polyol having a number average molecular weight of 3000, a functional group number of 3, and a polymer content of 20% by mass (manufactured by Sanyo Chemical Industries, Sannix FA-728R)
Polymer polyol 2: Polymer polyol having a number average molecular weight of 3000, a functional group number of 3, and a polymer content of 40% by mass (manufactured by Sanyo Chemical Industries, Sharp Flow FS-7301)
Polyether polyol: Polyoxypropylene glyceryl ether having a number average molecular weight of 600 and a functional group number of 3 (Sanix GP-600, manufactured by Sanyo Chemical Industries)
Polyester polyol 1: Polycaprolactone triol having a molecular weight of 850 and having 3 functional groups (Daicel Chemical Industries, Plaxel 308)
Polyester polyol 2: Adipate polyester polyol having a molecular weight of 530 and a functional group number of 2 (manufactured by Adeka, Adeka New Ace Y65-55)
Other polyol 1: Polyoxypropylene glycol having a number average molecular weight of 2000 and a functional group number of 2 (manufactured by Sanyo Chemical Industries, Sannix PP-2000)
Other polyols 2: polyoxypropylene glycol having a number average molecular weight of 400 and a functional group number of 2 (Sanix PP-400, manufactured by Sanyo Chemical Industries)
Isocyanate 1: Carbodiimide-modified isocyanate obtained by modifying monomeric MDI with carbodiimide, NCO content 31% (manufactured by Nippon Polyurethane Industry Co., Ltd., Millionate MTL)
Isocyanate 2: Polyisocyanate, NCO content 31% (manufactured by Nippon Polyurethane Industry Co., Ltd., C-1130)
Foam stabilizer 1: Silicone foam stabilizer (polydimethylsiloxane and polyoxyalkylene) at a mass ratio (foam stabilizer: solvent) of 50:50 using a low viscosity polyol (low molecular weight polyether polyol having a viscosity of 60 cps). Diluted substance (L-5617, manufactured by Momentive)
Foam stabilizer 2: A substance obtained by diluting a silicone foam stabilizer (polydimethylsiloxane and polyoxyalkylene) at a mass ratio (foam stabilizer: solvent) of 50:50 using alkylbenzene (M-5, L-5614).
Cross-linking agent: 1,4 butanediol (manufactured by Sankyo Chemical Co., Ltd.)
Catalyst: Stanas octoate (Johoku Chemical Co., Ltd.)
Thickener: Calcium carbonate (Shiraishi Calcium Co., Ltd.)
Colorant: Oil-based processed pigment (manufactured by Sanyo Dye)
The above-mentioned components were prepared at the blending ratios shown in Tables 1 and 2 below, and mixed raw materials for each Example and each Comparative Example were obtained. In addition, the notation of (A)-(C) in Table 1 and 2 shows the compound corresponding to each component of this-application claim, and the numerical value of each component in Table 1 and 2 represents a mass part. Subsequently, the mixed raw material was put into the mixing head, and the mixture was stirred and mixed to be homogeneous while mixing an inert gas (nitrogen) in the range of 69 to 77% by volume. Then, the mixed raw material was supplied onto a film having a predetermined thickness that was continuously supplied, and was heated and cured at 120 to 200 ° C. to obtain a sheet-like polyurethane foam.

  Comparative Example 1 is (B) an example not containing the second polyol, Comparative Example 2 is (C) an example not containing the third polyol, and Comparative Example 3 is a high content of (C) the third polyol. Each example is shown. Comparative Example 4 is a conventional flame retardant polyurethane foam that exhibits flame retardancy by containing a flame retardant.

  Next, the obtained polyurethane foams of Examples and Comparative Examples were evaluated for tensile strength, tear strength, compression residual strain, flame retardancy, and chlorine content. In addition to these evaluations, the resilience and volatile organic compound contents were also evaluated. The results are shown in Tables 1 and 2.

[Evaluation of tensile strength]
The tensile strength was measured according to JIS K6251.
[Evaluation of tear strength]
The tear strength was measured according to JIS K6252.

[Evaluation of compressive residual strain]
The compression residual strain was measured according to JIS K6401.
[Evaluation of flame retardancy]
Flame retardance was evaluated in accordance with UL94 regulations. Specifically, a test piece (length 50 ± 1 mm × width 150 ± 5 mm × any thickness) cut out from the polyurethane foam of each example and each comparative example is placed horizontally on a horizontally held wire mesh. The flame was indirect flame for 60 ± 11 seconds at one end, and the combustion speed and combustion behavior were observed. And the flame retardance was evaluated according to the following evaluation criteria.

A: Fire extinguished before reaching 100 mm from the front line, with a position 25 mm from one end of the test piece as a reference (front line).
A: The burning rate between 100 mm from the front line is 40 mm / min or less.

X: The burning rate between 100 mm from a surface line exceeds 40 mm / min.
[Evaluation of chlorine content]
The chlorine content was evaluated by ion chromatography in accordance with BS EN 14582: 2007.

[Evaluation of resilience]
A test piece sufficiently larger than φ15 mm cut out from the polyurethane foam of each example and each comparative example was pressed with a load of 1 kg by a low-pressure loader and released after 5 seconds. Then, the restoration time (seconds) from the release of the pressure to the restoration to the original thickness was measured. In addition, if the restoration time is 2 seconds or less, the resilience is good, and if it exceeds 4 seconds, low resilience is expressed.

[Evaluation of volatile organic compound content]
The volatile organic compound (VOC) content was evaluated according to VDA278 defined by the German Automobile Manufacturers Association (VDA). Specifically, a test piece (7 mg) cut out from the polyurethane foam of each example and each comparative example was placed in a glass tube and applied to a thermal desorption apparatus at a temperature of 90 ° C. for 30 minutes. The gas was analyzed by a gas chromatograph mass spectrometer.

表２に示すように、難燃剤を含有する比較例４は優れた難燃性を有するものの、塩素含量が極めて高いことが分かる。一方、表１及び２に示すように、（Ａ）第１のポリオール、（Ｂ）第２のポリオール、及び（Ｃ）第３のポリオールをすべて含有する各実施例は、難燃剤を含有せずとも、難燃剤を含有する比較例４と略同等の優れた難燃性を有している。そして、各実施例は引張強度が０．５９を超え、引裂強度が１．８を超え、圧縮残留歪が１０％未満であり、強度及び低圧縮残留歪性に優れていることが分かる。

As shown in Table 2, although Comparative Example 4 containing a flame retardant has excellent flame retardancy, it can be seen that the chlorine content is extremely high. On the other hand, as shown in Tables 1 and 2, each example containing (A) the first polyol, (B) the second polyol, and (C) the third polyol does not contain a flame retardant. Both have excellent flame retardancy substantially equivalent to that of Comparative Example 4 containing a flame retardant. Each example has a tensile strength exceeding 0.59, a tear strength exceeding 1.8, a compressive residual strain of less than 10%, and it can be seen that the strength and the low compressive residual strain are excellent.

  On the other hand, although the comparative example 1 which does not contain (B) 2nd polyol has the outstanding flame retardance, it was a result with low evaluation of tensile strength and compression residual strain. On the other hand, (C) Comparative Example 2 containing no third polyol also had excellent flame retardancy, but the evaluation of the tensile strength was low. From this result, when only one of (B) the second polyol or (C) the third polyol is added to (A) the first polyol, both the tensile strength and the tear strength are high, At the same time, low compressive residual strain cannot be exhibited, and high strength and low compressive residual strain can be exhibited only when both (B) the second polyol and (C) the third polyol are added. I can guess what I can do. Moreover, even if it is a case where all the 1st-3rd polyol is contained from the result of the comparative example 3, when it contains the (C) 3rd polyol excessively, low compression residual distortion property is exhibited. I can't understand.

  Furthermore, Example 4 using carbodiimide-modified isocyanate as the isocyanate resulted in a lower chlorine content than Example 10 using polymeric isocyanate. Example 4 using a foam stabilizer diluted with a low-viscosity polyol resulted in a lower volatile organic compound content than Example 11 using a foam stabilizer diluted with alkylbenzene. (C) Example 4 using a polycaprolactone polyester polyol having 3 functional groups as the third polyol resulted in a lower volatile organic compound content than Example 12 using an adipate polyester polyol. . Furthermore, (B) Examples 3-12 which contain 2nd polyol in the range of 7-10 mass parts was the result that resilience is large compared with Example 1 and 2 which is outside the same range. .

Claims (4)

A flame retardant polyurethane foam obtained by reacting and foaming a mixed raw material containing polyols and polyisocyanates by a mechanical floss method,
As the polyols,
(A) A first polyol composed of a polymer polyol having a number average molecular weight of 1500 to 4500 and a functional group number of 3 is 50 to 80 parts by mass based on 100 parts by mass of the whole polyols,
(B) a second polyol composed of a polyether polyol having a number average molecular weight of 300 to 900 and a functional group number of 3 is 5 to 16 parts by mass based on 100 parts by mass of the whole polyols;
(C) A flame retardant polyurethane foam comprising a third polyol composed of a polyester polyol having 2 or 3 functional groups and 1 to 6 parts by mass with 100 parts by mass as a whole of the polyols. 2. The flame-retardant polyurethane foam according to claim 1, wherein the polyisocyanate contains monomeric isocyanate, carbodiimide-modified isocyanate, or a prepolymer obtained using them as a starting material. The flame retardant polyurethane foam according to claim 1 or 2, wherein the (C) third polyol is a caprolactone-based polyester polyol having 3 functional groups. A method for producing a flame retardant polyurethane foam in which a mixed raw material containing polyols and polyisocyanates is reacted and foamed by a mechanical floss method,
As the polyols,
(A) A first polyol composed of a polymer polyol having a number average molecular weight of 1500 to 4500 and a functional group number of 3 is 50 to 80 parts by mass based on 100 parts by mass of the whole polyols,
(B) a second polyol composed of a polyether polyol having a number average molecular weight of 300 to 900 and a functional group number of 3 is 5 to 16 parts by mass based on 100 parts by mass of the whole polyols;
(C) A method for producing a flame-retardant polyurethane foam, wherein the third polyol composed of a polyester polyol having 2 or 3 functional groups is used in an amount of 1 to 6 parts by mass based on 100 parts by mass of the whole polyol. .