JP2007056062A - Polyurethane-foamed material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyurethane-formed material capable of suppressing the oxidation of the foamed material on melt-treating, and especially inhibiting the generation of volatile organic compounds. <P>SOLUTION: This polyurethane-formed material is obtained by reacting, foaming and curing the raw materials of the polyurethane-formed material including polyols, polyisocyanates, a catalyst and a blowing agent, and melt-treating the obtained foamed material by an explosion to remove cell membranes. In the raw materials of the polyurethane-foamed material, an anti-oxidant having 350-4,000 mean molecular weight is contained by 1-20 pts.mass based on 100 pts.mass polyols. The polyurethane-foamed material exhibits ≤0.03 ppm volatilized amount of acetaldehyde measured in accordance with JIS Z8808, ≤1.0 ppm volatilized amount of propionic acid and also ≤520 ppm total amount of volatile organic compounds. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polyurethane foam used as an automobile interior material and the like, and more particularly to a polyurethane foam from which a cell membrane has been removed by a melting treatment.

  This type of polyurethane foam is produced by reacting, foaming and curing raw materials for polyurethane foams, which are mainly composed of polyols, polyisocyanates, catalysts and foaming agents, and additives such as foam stabilizers. The

  And when obtaining a polyurethane foam with higher air permeability, after manufacturing a foam, the melting process which removes a cell membrane is given. This melting process blows off the cell membrane to leave a skeleton structure constituting the polyurethane foam. For example, in the melting process, a polyurethane foam having a large number of cells is accommodated in an explosion-proof container, and after degassing the container, hydrogen gas and oxygen gas as flammable gases are injected into the container. Thereafter, the mixture of hydrogen gas and oxygen gas is ignited and burned. By the pressure accompanying the combustion, the cell membrane that partitions a large number of cells in the polyurethane foam is broken to leave a three-dimensional network-like skeleton structure, thereby obtaining a polyurethane foam from which the cell membrane has been removed.

  However, in recent years, environmental standards for volatile organic compounds (VOCs) have been established in automobile interior materials, housing materials, and the like, and the concentration of formaldehyde and acetaldehyde, which are the cause of sick house syndrome, has been regulated. By the way, since polyurethane foam uses polyols or the like as its raw material, a part of the polyurethane foam composition is decomposed in the blasting during the melting treatment, and aldehydes having a pungent odor or carbon It has been confirmed that acids are generated, and these cause volatile organic compounds and odors. Conventionally, aldehydes having a pungent odor and carboxylic acid remain as they are in a polyurethane foam subjected to a melting treatment, and a unique odor may be emitted. It is desired to remove these.

From such a viewpoint, a polyurethane foam is produced from a foam raw material containing an ozone degradation inhibitor and an antioxidant, and a sealing material for an air conditioner made of the obtained polyurethane foam is known (for example, a patent) Reference 1). In addition, it is a foam manufactured from a raw material containing a polyol, a polyisocyanate, a catalyst, and an antioxidant, and the antioxidant is a polyurethane foam that is a polymer compound having a number average molecular weight of 400 or more (for example, , See Patent Document 2).
JP 2004-231949 A (page 2, page 9 and page 11) JP 2004-211032 A (2nd page, 9th page and 10th page)

  However, in the sealing material for an air conditioner described in Patent Document 1, when the polyol as a foam material is a polyether polyol, the resulting foam is easily deteriorated by ozone in the atmosphere, and the cell membrane is destroyed. As a result, the air permeability increases and the sealant does not function. Therefore, in order to prevent this, an ozone deterioration preventing agent is blended in the foam material. Furthermore, the antioxidant is used in combination with the ozone deterioration preventing agent, but its blending amount is a very small amount of 0.01 parts (Examples 1 to 3 in Patent Document 1). In addition, a melting process for removing the cell membrane of the foam is not performed. Therefore, the problem at the time of a melting process is not suggested.

  On the other hand, also in the polyurethane foam described in Patent Document 2, the blending amount of the antioxidant is an extremely small amount of 0.01 parts (Examples 1 to 5 in Patent Document 2). And it does not perform the melting process for removing the cell membrane of a foam, and the problem accompanying a melting process is not suggested. That is, the melting process is performed by combustion of a combustible gas, and the decomposition of the foam due to the oxidation reaction occurs due to the increase in pressure, temperature, etc., and the generation of volatile organic compounds is promoted.

  Accordingly, an object of the present invention is to provide a polyurethane foam that can suppress the oxidation of the foam during the melting treatment, and in particular, can suppress the generation of volatile organic compounds.

  In order to achieve the above object, the polyurethane foam of the invention described in claim 1 is obtained by reacting, foaming and curing a polyurethane foam raw material containing polyols, polyisocyanates, a catalyst and a foaming agent. A polyurethane foam obtained by melting a foam and removing a cell membrane, wherein an antioxidant having a number average molecular weight of 350 to 4000 is contained in a raw material of the polyurethane foam in an amount of 1 to 20 per 100 parts by mass of polyols. It is characterized by containing a mass part.

The polyurethane foam of the invention according to claim 2 is characterized in that, in the invention according to claim 1, the melting treatment is a blast treatment.
The polyurethane foam of the invention according to claim 3 is characterized in that, in the invention according to claim 1 or claim 2, the volatilization amount of acetaldehyde measured in accordance with JIS Z8808 is 0.03 ppm or less. To do.

  In the polyurethane foam of the invention according to claim 4, in the invention according to any one of claims 1 to 3, the volatilization amount of propionic acid measured in accordance with JIS Z8808 is 1.0 ppm or less. It is characterized by this.

  The polyurethane foam of the invention described in claim 5 is the invention according to any one of claims 1 to 4, wherein the polyol is a polyether polyol.

According to the present invention, the following effects can be exhibited.
In the polyurethane foam of the invention according to claim 1, the raw material of the polyurethane foam contains 1 to 20 parts by mass of an antioxidant having a number average molecular weight of 350 to 4000 per 100 parts by mass of polyols. The blending amount of the antioxidant is sufficiently larger than the conventional amount. In particular, radicals generated in the polyurethane foam during the melting process are generated when a combustible gas, oxygen gas, or the like passes through the melting process. Since this radical oxidizes the unreacted terminal hydroxyl group, the antioxidant is captured by the radical being captured, and the generation of volatile organic compounds such as aldehydes and carboxylic acids is suppressed. Moreover, since the number average molecular weight of the antioxidant is sufficiently large, it is presumed that energy relaxation accompanying the absorption and release of radicals is performed, and the decomposition of itself is suppressed. Therefore, the oxidation of the foam during the melting process is suppressed, and in particular, the generation of volatile organic compounds can be suppressed.

  In the polyurethane foam of the invention according to claim 2, the melting treatment is a blast treatment, and the oxidation accompanying the blast treatment can be sufficiently suppressed, and the effect of the invention according to claim 1 can be exhibited. .

  According to the polyurethane foam of the invention of claim 3, in addition to the effect of the invention of claim 1 or claim 2, the acetaldehyde volatilization amount is 0.03 ppm or less, so that the indoor concentration guideline value of acetaldehyde Can be cleared.

  In the polyurethane foam of the invention according to claim 4, in addition to the effects of the invention according to any one of claims 1 to 3, the volatilization amount of propionic acid is 1.0 ppm or less, which is based on propionic acid. Smell can be reduced.

  In the polyurethane foam of the invention according to claim 5, in addition to the effects of the invention according to any one of claims 1 to 4, when the polyol is a polyether polyol, the foam is formed by ozone in the atmosphere. Even when it easily deteriorates, the effect of the antioxidant can be sufficiently exerted.

In the following, embodiments that are considered to be the best of the present invention will be described in detail.
The polyurethane foam in this embodiment is manufactured as follows. That is, it is produced by removing a cell membrane by melting a foam obtained by reacting, foaming and curing raw materials of polyurethane foam containing polyols, polyisocyanates, a catalyst and a foaming agent. In this case, 1 to 20 parts by mass of an antioxidant having a number average molecular weight of 350 to 4000 is blended with 100 parts by mass of polyols in the raw material of the polyurethane foam. Here, the number average molecular weight of the antioxidant represents an average molecular weight in the case of a mixture, but in the present invention, it is used as a concept including the molecular weight in the case of a single compound. Moreover, the polyurethane foam of this embodiment means the foam which has an open-cell structure by a melting process, and does not have a restoring property.

First, the raw material of a polyurethane foam is demonstrated in order.
(Polyols)
As the polyols, polyether polyols or polyester polyols are used, and polyether polyols are preferable from the viewpoints of high reactivity with polyisocyanates and the polyurethane foam not hydrolyzing.

  As the polyether polyol, a polyether polyol composed of a polymer obtained by addition polymerization of propylene oxide and ethylene oxide to a polyhydric alcohol, a modified product thereof, and the like are used. Examples of the modified product include those obtained by adding acrylonitrile or styrene to the polyether polyol, or those obtained by adding both acrylonitrile and styrene. Here, the polyhydric alcohol is a compound having a plurality of hydroxyl groups in one molecule, and examples thereof include glycerin and dipropylene glycol.

  Specific examples of polyether polyols include triols obtained by addition polymerization of propylene oxide to glycerin and addition polymerization of ethylene oxide, and diols obtained by addition polymerization of propylene oxide to dipropylene glycol and addition polymerization of ethylene oxide. . Since these polyether polyols have a primary hydroxyl group at the terminal, the reactivity with the polyisocyanate is high. The average molecular weight of the polyether polyol is preferably 2000 to 4000. When the average molecular weight is less than 2,000, physical properties such as tensile strength of the resulting polyurethane foam are lowered, and when it exceeds 4000, the number of hydroxyl groups per unit amount of the polyurethane foam is reduced, resulting in polyisocyanates. It shows a tendency for the reactivity to decrease.

  The polyethylene oxide unit in the polyether polyol is preferably 5 to 10 mol%. When the polyethylene oxide unit is less than 5 mol%, the hydrophilicity of the polyether polyol decreases, and when it exceeds 10 mol%, the hydrophilicity becomes too high and the reactivity between the polyether polyol and the polyisocyanate tends to decrease. It is not preferable.

As polyester polyols, in addition to condensation polyester polyols obtained by reacting polycarboxylic acids such as adipic acid and phthalic acid with polyols such as ethylene glycol, diethylene glycol, propylene glycol and glycerin, lactone polyester polyols and polycarbonate systems A polyol is used. These polyols can change the number of functional groups and the hydroxyl value of the hydroxyl group by adjusting the kind of raw material component, the molecular weight, the degree of condensation, and the like.
(Polyisocyanates)
Next, the polyisocyanate to be reacted with the polyether polyol is a compound having a plurality of isocyanate groups, specifically tolylene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate. (NDI), triphenylmethane triisocyanate, xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate, isophorone diisocyanate (IPDI), modified products thereof and the like are used.

The isocyanate index (index) of the polyisocyanate is preferably set in the range of 100 to 130. When the isocyanate index is less than 100, physical properties such as hardness and tensile strength of the polyurethane foam deteriorate, and when it exceeds 130, the crosslinking density of the polyurethane foam becomes too high. Here, the isocyanate index represents the equivalent ratio of the isocyanate group of the polyisocyanate to the active hydrogen such as water as the hydroxyl group of the polyol and water as a foaming agent, expressed as a percentage.
(Foaming agent)
The foaming agent is for foaming a polyurethane resin to form a polyurethane foam. For example, pentane, cyclopentane, hexane, cyclohexane, dichloromethane, carbon dioxide gas, etc. are used in addition to water. Of these foaming agents, water is preferable because it can react quickly with polyisocyanates to generate sufficient carbon dioxide gas and is handled well. The blending amount of the foaming agent is preferably 1 to 5 parts by mass per 100 parts by mass of polyols. When the blending amount of the foaming agent is less than 1 part by mass, foaming becomes insufficient and it becomes difficult to obtain a low-density foam. On the other hand, when it exceeds 5 parts by mass, foaming becomes excessive and physical properties such as hardness and tensile strength of the foam are lowered.
(catalyst)
The catalyst is mainly for accelerating the urethanization reaction between polyols and polyisocyanates. Specific examples of the catalyst include triethylenediamine, dimethylethanolamine, tertiary amines such as N, N ′, N′-trimethylaminoethylpiperazine, organometallic compounds such as tin octylate (tin octoate), acetates, Alkali metal alcoholates are used alone or in combination. The compounding amount of the catalyst is preferably 0.5 to 1.5 parts by mass per 100 parts by mass of polyols. When the blending amount of the catalyst is less than 0.5 parts by mass, the urethanization reaction is not sufficiently progressed, and the mechanical properties of the foam tend to decrease. On the other hand, when the amount exceeds 1.5 parts by mass, the progress of the urethanization reaction is excessive, and the formation of the foam is biased.
(Foam stabilizer)
As the foam stabilizer, those generally used in the production of polyurethane foams can be used. Specific examples of the foam stabilizer include silicone compounds, anionic surfactants such as sodium dodecylbenzenesulfonate and sodium lauryl sulfate, polyether siloxane, and phenolic compounds. Among these, a linear or branched polyether-siloxane copolymer is preferable, and a linear polysiloxane-polyoxyalkylene copolymer having a low foam regulating power is particularly preferable in order to improve the connectivity. The blending amount of the foam stabilizer is preferably 0.5 to 2.5 parts by mass per 100 parts by mass of polyols. When the blending amount is less than 0.5 parts by mass, the foam regulating action during foaming of the polyurethane foam raw material is not sufficiently exhibited, and it becomes difficult to obtain a good foam. On the other hand, when it exceeds 2.5 parts by mass, the foam regulating action becomes stronger and the cell connectivity tends to be lowered.
(Antioxidant)
The antioxidant is a substance having an action of trapping radicals (free radicals) generated by the oxidation of the foam and stopping the oxidation, particularly at the time of melting the foam. As such an antioxidant, a compound having a high number average molecular weight and low volatility, that is, a compound having a number average molecular weight of 350 to 4000 is used. The number average molecular weight is preferably 350 to 1200. When the number average molecular weight is less than 350, the antioxidant volatilizes or decomposes during the melting process, and the volatilization amount of the volatile organic compound increases. On the other hand, when the number average molecular weight exceeds 4000, it is difficult to produce or obtain an antioxidant.

  This is because the use of such a high molecular weight antioxidant has an action of trapping radicals to stop oxidation, energy relaxation associated with radical absorption is easy, and decomposition of itself is suppressed. Further, the antioxidant donates hydrogen to a radical to become an antioxidant radical, and the radical becomes a stable radical as the number average molecular weight increases. In particular, during the melting treatment of the foam, it is presumed that the unreacted terminal hydroxyl group (hydroxyl group) in the foam is oxidized by the generated oxygen and nitrogen-derived radicals to generate aldehydes and carboxylic acids. For this reason, it is thought that oxidation can be stopped by blending an antioxidant into the raw material and capturing the radicals.

  As this antioxidant, calcium diethylbis III 3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl (methyl) phosphonate (number average molecular weight 695), 4,6-bis (octylthiomethyl)- o-cresol (number average molecular weight 424.7), ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate] (number average molecular weight 586.8), pentaerythritol Tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (number average molecular weight 1178), thiodiethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) ) Propionate] (number average molecular weight 643), octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphene) ) Propionate] (number average molecular weight 531), N, N′-hexane-1,6-diylbis [3- (3,5-di-tert-butyl-4-hydroxyphenylpropionamide)] (number average molecular weight 637) Hindered phenolic antioxidants such as 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol polymer (number average molecular weight 4000).

  In addition, hindered amine antioxidants such as bis- (4-octyl-phenyl) amine (number average molecular weight 393), 5,7-di-tert-butyl-3- (3,4-dimethylphenyl) -3H-benzofuran Examples include lactone antioxidants such as -2-one (number average molecular weight 350), phosphorus antioxidants, sulfur antioxidants, and the like. These antioxidants can be used alone or in combination of two or more.

The blending amount of the antioxidant is set to 1 to 20 parts by mass per 100 parts by mass of the polyols in order to fully exhibit the function of the antioxidant and prevent its harmful effects. The amount of the antioxidant is set to a particularly large amount compared to the conventional amount (0.01 parts by mass) in order to effectively exhibit the antioxidant function during the melting process. When the blending amount of the antioxidant is less than 1 part by mass, the function of the antioxidant cannot be sufficiently exhibited, and generation of volatile organic compounds such as acetaldehyde and propionic acid cannot be suppressed. . On the other hand, when the amount exceeds 20 parts by mass, the antioxidant inhibits reactions such as resinification reaction between polyols and polyisocyanates and foaming reaction between polyisocyanates and water. Further, physical properties such as tensile strength and elongation are lowered, and a desired foam cannot be obtained.
(Other ingredients)
In addition to the raw material of the polyurethane foam, a crosslinking agent, a filler, a stabilizer, a colorant, a flame retardant, a plasticizer and the like are blended as necessary.

Next, a method for producing a polyurethane foam using the above-mentioned polyurethane foam raw material will be described.
A polyurethane foam is produced by reacting the raw material of the polyurethane foam to be foamed and cured, but the reaction at that time is complicated, and basically the following reaction is mainly performed. That is, addition polymerization reaction of polyols and polyisocyanates (urethanization reaction, resinification reaction), foaming (foaming) reaction of polyisocyanates with water as a blowing agent, and reaction products of these and polyisocyanates And crosslinking (curing) reaction. When producing a polyurethane foam, a one-shot method in which a polyol and a polyisocyanate are directly reacted, or a polyol and a polyisocyanate are reacted in advance to obtain a prepolymer having an isocyanate group at the terminal, Any of the prepolymer methods in which polyols are reacted therewith can be employed. In any case, it is preferable to mix the antioxidant with the polyol. In that case, the antioxidant is sufficiently stirred and mixed with the polyol. Then, a foaming agent is mixed in a mixed liquid of polyols and polyisocyanates, or a mixed liquid of prepolymer and polyols, a foam stabilizer and a catalyst are added, and these raw materials are reacted, foamed and cured. Let

  As the foamed form, mold foaming is possible, but slab foaming is preferable. The slab foaming is performed by discharging the agitated and mixed raw material onto a belt conveyor, and the raw material reacts at room temperature and atmospheric pressure while the belt conveyor moves and spontaneously foams. Then, a slab foam is obtained by hardening (curing) in a drying furnace.

  Subsequently, in the melting process applied to the foam, the cell membrane is blown away by a blasting process to allow the cells to communicate, leaving only the skeleton structure. For example, a foam having a large number of cells is housed in an explosion-proof container (sealed container), and a mixture of combustible gas such as propane gas and oxygen filled in the container is ignited and burned. With the sparks and pressure scattered by this combustion, the cell membrane separating many cells in the foam is melted and blown to allow the cells to communicate, leaving only the three-dimensional network skeleton structure. A finished polyurethane foam is obtained. Therefore, since heat and pressure are applied to the foam by the melting treatment and the oxidation action is promoted, it is necessary to add an antioxidant to the foam in advance.

  The explosion-proof container is not particularly limited as long as it can accommodate a foam and can be evacuated. However, if the gap between the contained foam and the inner wall of the explosion-proof container becomes too large, the foam near the gap tends to sag when the combustible gas burns, so the explosion-proof container has the same shape as the foam. And the same volume is preferred. In that case, it is desirable to cut or laminate the foam. In addition, as a method for degassing the inside of the explosion-proof container, a method in which a vacuum pump is connected to the explosion-proof container can be used. If the deaeration is insufficient, the cells are not sufficiently communicated. Therefore, the deaeration is performed until the inside of the foam cell is sufficiently evacuated.

  The method for injecting the combustible gas and oxygen gas into the explosion-proof container is not particularly limited. Examples thereof include a method of injecting into an explosion-proof container through a mixer, a method of adjusting from a high-pressure cylinder to a partial pressure corresponding to a desired mixing ratio with a pressure reducing valve, and injecting from separate injection ports. Immediately after gas injection, the gas dispersion state in the explosion-proof container is non-uniform, so it is preferable to leave it for several minutes after gas injection.

  The combustible gas is not particularly limited as long as it is a gas that can be combusted in the presence of oxygen gas. For example, propane gas, methane gas, carbon dioxide gas, hydrogen gas, or the like is used. These flammable gases can be used alone or in admixture of two or more.

  The melt-treated polyurethane foam thus obtained has an open cell ratio of approximately 100% (closed cell ratio of approximately 0%) and an air permeability of 100 to 300 l / min. The polyurethane foam is used after being cut into a desired shape.

  Now, the operation of the present embodiment will be described. The polyurethane foam raw material is blended with an antioxidant having a number average molecular weight of 350 to 4000 in an amount of 1 to 20 parts by weight per 100 parts by weight of polyols, and the raw material is reacted. Foam is obtained by being foamed and cured, and the foam is melt-processed to produce the desired polyurethane foam. In particular, during the melting process, unreacted terminal hydroxyl groups of the foam are oxidized to generate free radicals.

  This free radical is trapped by the antioxidant dispersed in the foam and the oxidation is suppressed. In this case, since the antioxidant is blended in a larger amount than conventional, the free radical scavenging action works effectively. In addition, since the number average molecular weight of the antioxidant is large, it is considered that energy relaxation is easily performed in the repetition of free radical absorption, energy relaxation, and release, and the decomposition of the antioxidant itself is suppressed. In addition, since the antioxidant has low volatility and remains in the foam without being decomposed even after trapping free radicals, the total amount of volatile organic compounds can be suppressed.

The effects exhibited by the above embodiment will be described collectively below.
-In the polyurethane foam of this embodiment, the raw material of a polyurethane foam contains 1-20 mass parts of antioxidants of number average molecular weight 350-4000 per 100 mass parts of polyols. The amount of the antioxidant is sufficiently large compared to the conventional amount. In particular, radicals generated in the polyurethane foam during the melting process are generated when a combustible gas, oxygen gas, or the like passes through the melting process. Since this radical oxidizes the unreacted terminal hydroxyl group, the antioxidant is captured by the radical being captured, and the generation of volatile organic compounds such as aldehydes and carboxylic acids is suppressed. Moreover, since the number average molecular weight of the antioxidant is sufficiently large, it is presumed that energy relaxation accompanying the absorption and release of radicals is performed, and the decomposition of itself is suppressed. Therefore, the oxidation of the foam during the melting process is suppressed, and in particular, the generation of volatile organic compounds can be suppressed.

-Since the said melting process is a blasting process, the oxidation accompanying the blasting process can fully be suppressed.
Moreover, the indoor concentration guideline value of acetaldehyde can be cleared when the volatilization amount of acetaldehyde is 0.03 ppm or less. Furthermore, when the volatilization amount of propionic acid is 1.0 ppm or less, the odor based on propionic acid can be reduced.

In addition, the total organic solvent volatilization amount (TVOC) can be suppressed to 520 ppm or less, and for example, the environment in an automobile room or a residential room can be favorably maintained.
-Since the polyol of the polyurethane foam raw material is a polyether polyol, the effect of the antioxidant can be sufficiently exerted even when the foam is easily deteriorated by ozone in the atmosphere.

  -As mentioned above, by setting the blending amount of the antioxidant to 1 to 20 parts by mass per 100 parts by mass of polyols, foaming is performed well, and the density, hardness, tensile strength, The physical properties such as elongation can be maintained at the same level as that of the case where no antioxidant is added.

  In the embodiment, since the antioxidant used is a high molecular weight and low volatile compound and remains without volatilization in the polyurethane foam, the polyurethane foam is removed in the presence of light or under heating conditions. When used, it can trap radicals and stop oxidation. Therefore, generation | occurrence | production of volatile organic compounds, such as aldehydes and carboxylic acid, by deterioration of a polyurethane foam can be suppressed.

Hereinafter, the embodiment will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.
(Examples 1-9 and Comparative Examples 1-10)
First, the raw material of the polyurethane foam which consists of polyols, polyisocyanates, a foaming agent, a foam stabilizer, and a catalyst used by each Example and the comparative example is shown below. As the antioxidant, four kinds of substances were used, which were A, B, C, and D, respectively.

  Polyol: Polyether polyol, number of functional groups 3, hydroxyl value 56.1 (mgKOH / g), molecular weight 3000, trade name, GP-3050F, manufactured by Sanyo Chemical Industries. This GP-3050F is a compound in which propylene oxide and ethylene oxide (content of 7% by mass) are added to glycerin.

  Polyisocyanate: 80/20 (mass ratio) mixture of 2,4-TDI / 2,6-TDI, trade name T-80 manufactured by Nippon Polyurethane Industry Co., Ltd. This polyisocyanate was blended so that the isocyanate index was 110.

Foaming agent: tap water.
Catalyst: Triethylenediamine, trade name 33LV, manufactured by Air Products.

Metal catalyst: stannous octylate, trade name manufactured by Johoku Chemical Co., Ltd .; MRH-110.
Foam stabilizer: Silicone foam stabilizer, trade name SZ-1136 manufactured by Toray Dow Corning Co., Ltd.
Antioxidant A: tributylhydroxytoluene (BHT) (molecular weight 278).

  Antioxidant B: Pentaerythritol tetrakis [3- (3,5-tert-butyl-4-hydroxyphenyl) propionate], manufactured by Ciba Specialty Chemicals Co., Ltd., trade name Irganox 1010 (number average molecular weight 1178).

Antioxidant C: bis- (4-octyl-phenyl) amine (number average molecular weight 393).
Antioxidant D: 5,7-di-tert-butyl-3- (3,4-dimethylphenyl) -3H-benzofuran-2-one (number average molecular weight 350).

  And each of these raw materials was mix | blended with the compounding quantity shown in Table 1 and Table 2, and the raw material of the polyurethane foam in each Example and a comparative example was prepared. Thereafter, the raw material was reacted, foamed and cured by slab foaming to produce a foam. In this case, in Comparative Examples 1 and 2, no antioxidant was blended, and in Comparative Example 1, no melting treatment was performed. In Comparative Examples 3 and 4, BHT having a low molecular weight of 278 was used as an antioxidant. In Comparative Example 5, an example in which the blending amount of the antioxidant is small and in Comparative Example 6 an example in which the blending amount of the antioxidant is large are shown. Furthermore, in Comparative Examples 7 and 8, examples in which the antioxidant C was added in an excessive amount and an excessive amount were shown. In Comparative Examples 9 and 10, an example in which the antioxidant D was added in an excessive amount and an excessive amount was shown.

  These foams were melted. The melting process was carried out by containing the foam in an explosion-proof container and sufficiently degassing, then injecting a mixed gas of propane gas and oxygen gas, igniting and burning. About the obtained polyurethane foam after melting treatment, density, hardness, tensile strength, elongation, volatilization amount of acetaldehyde, volatilization amount of propionaldehyde, volatilization amount of propionic acid and volatilization amount of all organic solvents (TVOC) Evaluation was made by the method shown below. The results are shown in Tables 1 and 2.

Density (kg / m ³ ): Measured according to JIS K7222 (1999).
Hardness (N): Measured according to JIS K6400-2 (Method A).
Tensile strength (kPa): measured in accordance with JIS K6400-5 (2004).

Elongation (%): Measured according to JIS K6400-5 (2004).
The volatilization amount (ppm) of acetaldehyde, propionaldehyde and propionic acid was measured by the following method. That is, after putting a polyurethane foam sample (length 30 mm, width 30 mm and thickness 5 mm) into a 1 L glass desiccator, nitrogen substitution is performed and the sample is left in a constant temperature bath at 65 ° C. for 2 hours. Thereafter, the gas in the glass desiccator was sucked, and measurement was carried out using a gas chromatograph in accordance with JIS Z8808. The indoor concentration guideline value of acetaldehyde set by the Ministry of Health, Labor and Welfare on January 22, 2002 is 48 μg / m ³ (0.03 ppm). This 48 μg / m ³ (0.03 ppm) is referred to as an acetaldehyde indoor concentration guide value.

  TVOC (ppm): The total organic solvent volatilization amount was measured by VDA (German Automobile Manufacturers Association) 278 (gas chromatography thermal desorption method).

表１に示した結果から、実施例１〜３においては、アセトアルデヒド及びプロピオンアルデヒドの揮発量を０．０３ｐｐｍ以下に抑えることができるとともに、プロピオン酸の揮発量を１．０ｐｐｍ以下に抑えることができ、しかもＴＶＯＣを５１０ｐｐｍ以下に抑制することができた。さらに、ポリウレタン発泡体の密度、硬さ、引張強さ及び伸びについて、熔解処理をしなかった場合（比較例１）と同等に維持することができた。

From the results shown in Table 1, in Examples 1 to 3, the volatilization amount of acetaldehyde and propionaldehyde can be suppressed to 0.03 ppm or less, and the volatilization amount of propionic acid can be suppressed to 1.0 ppm or less. And TVOC was able to be suppressed to 510 ppm or less. Furthermore, the density, hardness, tensile strength, and elongation of the polyurethane foam could be maintained at the same level as when the melting treatment was not performed (Comparative Example 1).

  On the other hand, in the comparative example 2 which did not mix | blend antioxidant and performed the melting process, the volatilization amount of acetaldehyde, propionaldehyde, and propionic acid increased compared with the comparative example 1 which did not perform a melting process. This indicates that the decomposition of the foam is promoted by the melting process. In Comparative Example 1, since an antioxidant was not blended, a value larger than 0.03 ppm, which is an indoor concentration guideline value for acetaldehyde, was shown. In Comparative Examples 3 and 4, since a low molecular weight antioxidant was used, TVOC reached a high concentration of 2000 to 8000 ppm. Further, in Comparative Example 4 in which an excessive amount of the low molecular weight antioxidant A was blended, the foamed state was slightly poor, and the polyurethane foam was poorly stretched. This indicates that the low molecular weight antioxidant A having a molecular weight of less than 350 is easily decomposed by the melting process and has a weak antioxidant effect. In Comparative Example 5, since the blending amount of the antioxidant B was small, the volatilization amount of acetaldehyde, propionaldehyde and propionic acid increased. On the other hand, in Comparative Example 6, since the blending amount of the antioxidant B was too large, the foamed state was slightly poor and the elongation of the polyurethane foam was also lowered.

表２に示した結果から、実施例４〜９においては、アセトアルデヒドの揮発量を０．０３ｐｐｍ以下に抑えることができ、プロピオン酸の揮発量を１．０ｐｐｍ以下に抑えることができ、しかもＴＶＯＣを５２０ｐｐｍ以下に抑制することができた。しかも、ポリウレタン発泡体の密度、硬さ、引張強さ及び伸びについて、熔解処理をしなかった場合（比較例１）と同等に維持することができた。

From the results shown in Table 2, in Examples 4 to 9, the volatilization amount of acetaldehyde can be suppressed to 0.03 ppm or less, the volatilization amount of propionic acid can be suppressed to 1.0 ppm or less, and TVOC is reduced. It could be suppressed to 520 ppm or less. Moreover, the density, hardness, tensile strength, and elongation of the polyurethane foam could be maintained equivalent to the case where the melting treatment was not performed (Comparative Example 1).

  On the other hand, in Comparative Example 7, since the blending amount of the antioxidant C was small, the volatilization amount of acetaldehyde, propionaldehyde and propionic acid increased. On the other hand, in Comparative Example 8, since the blending amount of the antioxidant C was too large, the foamed state was slightly poor, and physical properties such as tensile strength and elongation of the polyurethane foam were lowered. In Comparative Example 9, since the blending amount of the antioxidant D was small, the volatilization amount of acetaldehyde, propionaldehyde and propionic acid increased. On the other hand, in Comparative Example 10, since the blending amount of the antioxidant D was too large, the foamed state was somewhat poor and the physical properties such as tensile strength and elongation of the polyurethane foam were lowered.

In addition, the said embodiment can also be changed and actualized as follows.
-As an antioxidant, it can combine and use several antioxidants from which a kind, molecular weight, etc. differ, and changes the compounding quantity.

-Focusing on aldehydes such as formaldehyde and carboxylic acids such as acetic acid as volatile components, the conditions can be set so as to reduce them.
Further, the technical idea that can be grasped from the embodiment will be described below.

  The polyurethane foam according to any one of claims 1 to 5, wherein a foam stabilizer is included in a raw material of the polyurethane foam. When configured in this way, in addition to the effects of the invention according to any one of claims 1 to 5, the polyurethane can smoothly foam and has excellent physical properties such as hardness and tensile strength. A foam can be obtained.

  The polyurethane foam according to any one of claims 1 to 5, wherein the total organic solvent volatilization amount by VDA (German Automobile Manufacturers Association) 278 (gas chromatography thermal desorption method) is 520 ppm or less. body. In this case, in addition to the effects of the invention according to any one of claims 1 to 5, the polyurethane foam can be suitably used as an interior part for an automobile.

Claims (5)

A polyurethane foam obtained by reacting, foaming and curing a polyurethane foam material containing polyols, polyisocyanates, a catalyst and a foaming agent to melt and remove the cell membrane.
The polyurethane foam is characterized in that the raw material of the polyurethane foam contains 1 to 20 parts by mass of an antioxidant having a number average molecular weight of 350 to 4000 per 100 parts by mass of polyols. The polyurethane foam according to claim 1, wherein the melting treatment is a blasting treatment. The polyurethane foam according to claim 1 or 2, wherein the volatilization amount of acetaldehyde measured in accordance with JIS Z8808 is 0.03 ppm or less. The polyurethane foam according to any one of claims 1 to 3, wherein the volatilization amount of propionic acid measured in accordance with JIS Z8808 is 1.0 ppm or less. The polyurethane foam according to any one of claims 1 to 4, wherein the polyol is a polyether polyol.