Patent Description:
Flexible polyurethane foams are widely used in living goods, automotive materials, clothes, sports and leisure goods, medical materials, civil engineering and construction materials, and the like. Among such application fields, particularly in applications for automobile seat such as a seat cushion and a seat back, reduction in density of the flexible polyurethane foam is required, for cost reduction and weight reduction for coping with fuel efficiency regulation.

The flexible polyurethane foam is generally obtained by mixing a polyol component, a catalyst, a foam stabilizer, a foaming agent and a polyisocyanate component, and by reacting the isocyanate group with an active hydrogen group. In the past, there has been a period when chlorofluorocarbon type and organic type forming agents were used as foaming agents, but in recent years, water that reacts with an isocyanate group in polyisocyanate to generate carbonic acid gas has become the mainstream because of environmental concerns. In a flexible polyurethane molded foam in which the foam is obtained by foaming and curing the materials in a mold, such a method is general as to supply two liquids of a polyol composition in which a polyol component, a catalyst and a foam stabilizer are previously mixed with water of a foaming agent, and of a polyisocyanate component, to a foaming apparatus, and to mix and discharge the two liquids into the mold via a mixing head; and it is effective means for responding to a desire of lowering density to increase the amount of the water to be blended in the polyol composition and to increase the amount of the carbonic acid gas to be generated.

The polyisocyanate component is roughly divided into a TDI-based polyisocyanate component which is mainly consisting of tolylene diisocyanate (TDI), and an MDI-based polyisocyanate component which is mainly consisting of a mixture of diphenylmethane diisocyanate (MDI) and polyphenyl polymethylene polyisocyanate (P-MDI). As for the TDI-based polyisocyanate component, a content of a isocyanate group is high and an amount of carbonic acid gas to be generated per unit weight by a reaction with water is large, and accordingly the TDI-based polyisocyanate component can lower the density without increasing the amount of the water to be blended so much; but there are such problems that the TDI of a raw material tends to easily aggravate a working environment of a production site of the flexible polyurethane foam, because the vapor pressure is high and the toxicity is strong, and that the flexible polyurethane foam obtained by TDI which is bifunctional isocyanate is low in durability.

On the other hand, the MDI-based polyisocyanate component has a tendency opposite to that of the TDI-based polyisocyanate component, and is superior to the TDI-based polyisocyanate component in the points of the working environment and the foam durability, but is low in the content of the isocyanate group, and needs to blend a large amount of water in order to lower the density. There has been a problem of aggravating the compatibility between a hydrophobic component mainly containing a polymer polyol and hydrophilic components such as a catalyst, low molecular weight polyol and polyether polyol which contains a large amount of an ethylene oxide unit, by blending a large amount of water in the polyol composition, and lowering the stability over time of the polyol composition. As means for improving the stability over time of the polyol composition, it is proposed in <CIT> to use a polyether polyol which has oxyethylene units in a specific range and a high primarization ratio of a terminal end. However, in this method, the compatibility between the hydrophilic component and the hydrophobic component is not sufficiently improved for a polyol composition in which such a large amount of water as to exceed <NUM> mass% is blended. Such a problem tends to occur that the polyol composition during storage is decomposed particularly in the summer season in which ambient temperature is high, and the uniformity of foam performance cannot be kept.

<CIT> relates to a polyol composition obtained by mixing <NUM> pts. liquid polyol with <NUM>-<NUM> pts. powdery melamine of a mean particle diameter of <NUM>-<NUM>, <NUM>-<NUM> pts. dispersant selected from among an alkanolamide nonionic surfactant, a higher alcohol ethoxysultate salt anionic surfactant and an amino acid salt anionic surfactant and <NUM>-<NUM> pts.

<CIT> relates to compatibilizers for mutually immiscible polyol compositions, characterized in that they comprise dispersed particles, and processes for production of these and their use in polyurethane foams.

<CIT> relates to metathesized triacylglycerol green polyols, their related physical and thermal properties and their use as a component of polyurethane applications, including polyurethane foams.

<CIT> relates to a polyol composition for producing a flexible polyurethane foam, which contains: a polyol mixture containing a polyol; and a surfactant having an HLB of <NUM> to <NUM> and selected from a group consisting of an anionic surfactant, a cationic surfactant and an ampholytic surfactant, and in which the content of a polyethylene oxide unit in the polyol mixture is <NUM> to <NUM> wt. % based on the weight of the polyol mixture.

<CIT> relates to a water-absorbing polyurethane foam which is produced by reacting polyols with a polyisocyanate compound in the presence of a catalyst, a foaming agent, and a foam stabilizer, wherein a polyester polyol is used as the polyols and an anionic surfactant is used as the foam stabilizer.

<CIT> relates to an impregnating agent composition for consolidation of a rock bed or ground comprising a diphenylmethane diisocyanate based polyisocyanate composition (A), an aqueous silicate solution (B), a polypropylene glycol and/or a polyethylene glycol (C), an amine compound (D) and a compatibilizer (E), wherein a naphthalenesulfonic acid based surface active agent is used as the compatibilizer (E).

The present invention has been designed with respect to the above background art, and is directed at providing a polyol composition that can secure the stability over time even when a large amount of water is blended in the polyol composition, a flexible polyurethane foam that uses the polyol composition, is low in density and is excellent in durability; and a method for producing the same.

As a result of having made an extensive investigation, the present inventors have found that the above described problems can be solved by that a polyol composition contains a specific compatibilizing agent, and have accomplished the present invention.

Specifically, the present invention includes the following embodiments.

According to the present invention, a flexible polyurethane foam can be obtained which has stability over time of the polyol composition secured and has excellent durability even though the density is low, even in the case where a large amount of water has been blended in the polyol composition, when the flexible polyurethane foam is molded.

The present invention will be described in more detail.

The polyol composition for flexible polyurethane foam of the present invention comprises a polyol component (A), a catalyst (B), a foam stabilizer (C), a foaming agent (D) and a compatibilizing agent (E), which are described below.

The polyol component (A) is one which forms polyurethane by causing addition polymerization with diisocyanate, and in the present invention, is preferably at least one selected from the group consisting of polyether polyols and polyester polyols. Furthermore, it is more preferable that a number average molecular weight is <NUM> to <NUM>, and the number of nominal functional groups is <NUM> or more. When the number average molecular weight is less than the lower limit, a flexibility of a foam to be obtained becomes insufficient, and when exceeding the upper limit, the hardness of the foam tends to decrease. In addition, when the number of the nominal functional groups is less than <NUM>, there arises a problem that a compression residual strain which is an index of durability deteriorates. For information, the number of the nominal functional groups means the number of theoretical average functional groups (number of active hydrogen atoms per molecule), when it is assumed that a side reaction does not occur during the polymerization reaction of polyol.

Examples of the polyether polyol to be used include polypropylene ethylene polyol and polytetramethylene ether glycol (PTG); and examples of the polyester polyol to be used include a polyester polyol that consists of adipic acid and ethylene glycol, which is a polycondensation type polyester-based polyol, and polycaprolactone polyol of a lactone-based polyester polyol.

As the catalyst (B), various urethanated catalysts known in the relevant field can be used, and examples thereof include triethylamine, tripropylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, dimethylbenzylamine, N,N,N',N'-tetramethylhexamethylenediamine, N,N,N',N',N"-pentamethyldiethylenetriamine, bis-(<NUM>-dimethylaminoethyl) ether, triethylenediamine, <NUM>,<NUM>-diaza-bicyclo[<NUM>. <NUM>]undecene-<NUM>,<NUM>,<NUM>-dimethylimidazole, dimethylethanolamine and N,N-dimethyl-N-hexanolamine; further organic acid salts thereof; and also organometallic compounds such as stannous octoate and zinc naphthenate. In addition, amine catalysts having active hydrogen such as N,N-dimethylethanolamine and N,N-diethylethanolamine are also preferable.

It is preferable that an amount of the catalyst (B) to be added is <NUM> to <NUM> mass% with respect to the polyol component (A). If the amount of the catalyst (B) to be added is less than the lower limit value, the curing tends to be insufficient, and if the amount of the catalyst (B) to be added exceeds the upper limit value, it may occur that the moldability deteriorates.

As the foam stabilizer (C), a usual surfactant is used, and an organosilicon-based surfactant can be suitably used. Examples of the foam stabilizer (C) include: SZ-<NUM>, SZ-<NUM>, SZ-<NUM> and SZ-<NUM> made by Dow Corning Toray Co. ; Y-<NUM> and L-<NUM> made by Momentive Corporation; and B-<NUM> LF2 and B-<NUM> LF2 made by Evonik Japan Co. ; and F-<NUM> made by Shin-Etsu Chemical Co. It is preferable that an amount of these foam stabilizers is <NUM> to <NUM> mass% with respect to the polyol component (A).

As the foaming agent (D), water is used. Water reacts with an isocyanate group to generate carbonic acid gas, and thereby can form foam. In addition, an arbitrary foaming agent may be used additionally with water. For example, a small amount of an organic compound having a low boiling point such as cyclopentane and isopentane may be concomitantly used; or it is possible to form foam by using a gas loading device and mixing and dissolving air, nitrogen gas or liquefied carbon dioxide into a stock solution. An amount of the foaming agent to be added is usually <NUM> to <NUM> mass% with respect to the polyol component (A), but when it is intended to obtain a low density flexible polyurethane foam of which an apparent density is less than <NUM>/m<NUM>, it is preferable to be <NUM> to <NUM> mass%, and is further preferable to be <NUM> to <NUM> mass%. If the amount of the foaming agent to be added exceeds the upper limit, there is the case where foaming resists being stabilized, and if the amount is less than the lower limit, there is the case where the density of the foam may not be sufficiently lowered. When a large amount of water of <NUM> mass% or more is added, it is possible to secure stability over time of the polyol composition by adding the compatibilizing agent (E) of the present invention.

The compatibilizing agent (E) in the present invention is an anionic surfactant having a hydrophilic portion and a hydrophobic portion. The hydrophilic portion of the compatibilizing agent (E) has a salt (alkali metal salt) consisting of an anionic polar group and an alkali metal; specifically an alkali metal salt of sulfonic acid, wherein the alkali metal salt of the hydrophilic portion is a sodium salt.

In addition, the hydrophobic portion of the compatibilizing agent (E) has an aromatic ring. The anionic surfactant having these structures is a sodium salt of a naphthalenesulfonic acid formalin condensate.

Examples of the sodium salt of the naphthalenesulfonic acid formalin condensate include: a sodium salt of a β-naphthalenesulfonic acid formalin condensate; and a sodium salt of an alkylnaphthalene sulfonic acid formalin condensate.

As for the amount of the compatibilizing agent (E) to be added, it contains <NUM> to <NUM> mass% with respect to the polyol component (A). If the amount is less than the lower limit value, it is difficult to obtain an effect of improving the compatibility, and if the amount exceeds the upper limit value, the moldability of the foam occasionally deteriorates.

By using the above described polyol composition comprising the polyol component (A), the catalyst (B), the foam stabilizer (C), the foaming agent (D) and the compatibilizing agent (E), it is possible to secure adequate compatibility even when a large amount of water has been blended in the polyol composition.

In addition, in the present invention, it is preferable that the polyol component (A) contains at least one cyclic glycol selected from the group consisting of alicyclic glycols and aromatic glycols (hereinafter referred to simply as "cyclic glycol").

The cyclic glycol is a compound having a cyclic structure in the compound, and examples of the cyclic glycol include cyclohexane diol, cyclohexane dimethanol, hydroquinone bis(<NUM>-hydroxyethyl) ether, dihydroxydiphenyl methane, a hydride of bisphenol A, polyoxyethylene bisphenol ether and polyoxypropylene bisphenol ether. Among these, <NUM>,<NUM>-cyclohexanedimethanol and polyoxyethylene bisphenol A ether are preferable, from the viewpoint that an effect of improving the wet heat compression strain of a flexible polyurethane foam to be obtained is high.

It is preferable for the content of the cyclic glycol to be <NUM> to <NUM> mass%, and is more preferable to be <NUM> to <NUM> mass%, with respect to the polyol component (A).

In the present invention, the flexible polyurethane foam can be obtained by mixing the above described polyol composition for molding a flexible polyurethane foam and the polyisocyanate component (F), and forming foam.

As for the polyisocyanate component (F), it is preferable to use diphenylmethane diisocyanate (hereinafter referred to as MDI) such as <NUM>,<NUM>'-diphenylmethane diisocyanate (hereinafter referred to as <NUM>,<NUM>'-MDI), <NUM>,<NUM>'-diphenylmethane diisocyanate (hereinafter referred to as <NUM>,<NUM>'-MDI) and <NUM>,<NUM>'-diphenylmethane diisocyanate (hereinafter referred to as <NUM>,<NUM>'-MDI), and polyphenylene polymethylene polyisocyanate (hereinafter referred to as P-MDI), as an isocyanate source. In the present invention, various modified products of the above described MDI, a mixture of MDI and P-MDI, a urethane modified product, a urea modified product, an allophanate modified product, a biuret modified product and the like can also be used.

It is preferable that a rate of MDI content of the polyisocyanate component (F) according to the present invention is in a range of <NUM> to <NUM> mass%. If the rate of MDI content exceeds <NUM> mass%, there is a possibility that the storage stability at low temperature of the polyisocyanate composition to be obtained and the durability of a flexible foam to be obtained are lowered; and on the other hand, if the MDI content is less than <NUM> mass%, there is a possibility that the elongation of the flexible polyurethane foam decreases and it becomes difficult to obtain a sufficient foam strength, as the crosslink density increases.

Furthermore, it is preferable that the total of a content of <NUM>,<NUM>'-MDI and a content of <NUM>,<NUM>'-MDI with respect to the total amount of MDI (hereinafter referred to as isomer content) is <NUM> to <NUM> mass%.

When the content of <NUM>,<NUM>'-MDI and <NUM>,<NUM>'-MDI with respect to the total amount of MDI according to the present invention is less than <NUM> mass%, there is a possibility that the storage stability at low temperature of the obtained polyisocyanate composition is impaired, and there is the case where it becomes necessary to constantly warm an isocyanate storage place, pipes and the inside of the foam molding machine. In addition, the molding stability of the flexible polyurethane foam tends to be easily impaired, and there is the case where foam collapse and the like occur in a middle of forming foam. On the other hand, when the content exceeds <NUM> mass%, the reactivity is lowered, and there is a possibility that such problems occur that a molding cycle is extended, a closed cell ratio of foam becomes high, and the foam shrinks after having been molded.

In the production of the flexible polyurethane foam of the present invention, it is possible to use various well-known additives or auxiliary agents such as fillers like calcium carbonate and barium sulfate, flame retardants, plasticizers, coloring agents and antifungal agents, as needed.

By use of the polyol composition and the polyisocyanate component as described above in the present invention, it is possible to suitably obtain such a flexible polyurethane foam that an apparent density is less than <NUM>/m<NUM>, and that a <NUM>% compression hardness of a foam test piece provided with a skin is <NUM> to <NUM> N/<NUM><NUM>, a coefficient of hysteresis loss thereof is less than <NUM>%, and a wet heat compression strain thereof is less than <NUM>%.

In addition, by the polyol component (A) containing the above described cyclic glycol, the wet heat compression strain is further improved, and the value can be controlled to less than <NUM>%.

Next, a method for producing the flexible polyurethane foam of the present invention will be described.

The flexible polyurethane foam of the present invention can be produced by making a mixture of a polyol component (A), a catalyst (B), a foam stabilizer (C), a foaming agent (D), a compatibilizing agent (E) and a polyisocyanate component (F) react and forming foam.

A molar ratio (NCO/ active hydrogen) of the total isocyanate groups to all the active hydrogen groups in chemical compounds containing active hydrogen groups, which include water, in the polyisocyanate composition of the present invention, at the time of mixing and foaming, is <NUM> to <NUM> (isocyanate index (NCO INDEX) = <NUM> to <NUM>), and as for an adequate range for the durability and molding cycle of the foam, it is preferably <NUM> to <NUM> (NCO INDEX = <NUM> to <NUM>).

When the NCO INDEX is less than <NUM>, the durability lowers and a closed cell property excessively rises; and when the NCO INDEX is higher than <NUM>, there is the case where the molding cycle is extended due to unreacted isocyanate which has remained for a long period of time, and cell collapse occurs in a middle of forming foam due to the delay of change to high molecular weight.

As for a method for producing the flexible polyurethane foam, it is possible to use a method for producing a flexible polyurethane molded foam (hereinafter referred to as flexible mold foam) of: injecting a foaming stock solution of a mixed liquid of the above described polyol component (A), the catalyst (B), the foam stabilizer (C), the foaming agent (D), the compatibilizing agent (E), and the polyisocyanate component (F) into a mold; and then forming foam and curing the foaming stock solution.

A mold temperature at the time when the above described foaming stock solution is injected into the mold is usually <NUM> to <NUM>, and preferably is <NUM> to <NUM>. If the mold temperature at the time when the above described foaming stock solution is injected into the mold is lower than <NUM>, the temperature leads to an extension of the production cycle due to lowering of the reaction rate: and on the other hand, if the temperature is higher than <NUM>, the reaction between water and isocyanate is excessively promoted, in the reaction of the polyol and the isocyanate, and there is the case where the foam thereby collapses in a middle of forming foam.

The curing time at the time when the above described foaming stock solution is foamed and cured is preferably <NUM> minutes or shorter, and is more preferably <NUM> minutes or shorter, in consideration of a production cycle of a general flexible mold foam.

When the flexible mold foam is produced, each of the above described components can be mixed by using a high-pressure foaming machine, a low-pressure foaming machine or the like, similarly to the case of an ordinary flexible mold foam.

It is preferable to mix the isocyanate component and the polyol component just before forming foam. It is possible to premix the other components with the isocyanate component or the polyol component within such a range as not to affect the storage stability of the raw material or the change over time in reactivity. Those mixtures may be used immediately after mixing, or after storage, a necessary amount may be used appropriately. In the case of a foaming apparatus into a mixing section of which more than two components can be simultaneously introduced, it is also possible to individually introduce the polyol, the foaming agent, the isocyanate, the catalyst, the foam stabilizer, the additive and the like, into the mixing section.

In addition, a mixing method may be any of dynamic mixing of performing mixing in mixing chamber in a machine head of a foaming machine, and static mixing of performing mixing in a liquid feeding pipe; or may concomitantly use both. There are many cases where mixing of a gaseous component such as a physical foaming agent with a liquid component is performed by the static mixing, and mixing of components that can be stably stored as a liquid is performed by dynamic mixing. It is preferable that the foaming apparatus to be used in the present invention is a high pressure foaming apparatus which does not need to wash the mixing section with a solvent.

The mixed solution obtained by such mixing is discharged into a metal mold (mold), is foamed and cured, and then is demolded. It is also preferable to previously apply a release agent to the metal mold, so as to smoothly perform the above described demolding. As for the releasing agent to be used, it is acceptable to use a releasing agent which is usually used in a molding and manufacturing field.

The demolded product can be used as it is, but it is preferable to destroy a cell membrane of the foam under compression or under reduced pressure by a conventionally known method, and to stabilize an appearance and dimension of a subsequent product.

By the method for producing the flexible polyurethane foam of the present invention, such a flexible polyurethane foam can be obtained that the apparent density is less than <NUM>/m<NUM>, the <NUM>% compression hardness of the foam test piece provided with the skin is <NUM> to <NUM> N/<NUM><NUM>, the coefficient of hysteresis loss is less than <NUM>%, and the wet heat compression strain is less than <NUM>%.

The present invention will be described more specifically in detail based on Examples and Comparative Examples. Incidentally, unless otherwise specified, "parts" and "%" in the text are based on mass.

A reactor equipped with a stirrer, a cooling tube, a nitrogen inlet tube and a thermometer was purged with nitrogen, and then <NUM> of polyol <NUM>, <NUM> of polyol <NUM>, <NUM> of a compatibilizing agent <NUM>, <NUM> of a catalyst <NUM>, <NUM> of a catalyst <NUM>, <NUM> of a foam stabilizer <NUM> and <NUM> of water were charged into the reactor; the mixture was stirred at <NUM> for <NUM> hours; and a polyol composition (P-<NUM>) was obtained. Other polyol compositions (P-<NUM> to P-<NUM>) were also prepared similarly to P-<NUM>. The results are shown in Table <NUM> and Table <NUM>.

A liquid temperature of a mixture (polyol composition) of all the raw materials except for a polyisocyanate compound among raw materials shown in Table <NUM> was adjusted to <NUM> to <NUM>, and a polyisocyanate component was adjusted at a liquid temperature of <NUM> to <NUM>. A predetermined amount of the polyisocyanate component was added to the polyol composition, the mixture was mixed by a mixer (<NUM> revolutions per minute) for <NUM> seconds, the mixed substance was injected into a mold, the flexible polyurethane foam was foamed, then the foam was taken out from the mold, and the obtained flexible polyurethane foam was subjected to measurement of physical properties. For information, NCO Index in Table <NUM> is a ratio of NCO groups to the number of active hydrogen atoms existing in the blend.

In the table, the evaluation of moldability "○" means that the flexible polyurethane foam can be molded without causing such a collapse that the urethane foam reaches a maximum height and then greatly sinks, or such a phenomenon that the formed urethane foam shrinks immediately after having been foamed or after having been cured.

An apparent density was determined according to the method described in JIS K <NUM>.

[<NUM>% compression hardness (<NUM>% ILD) of foam test piece provided with skin].

The compression hardness was determined according to Method B described in JIS K <NUM>.

The coefficient of hysteresis loss was measured according to Method B described in JIS K <NUM>.

The compression strain was measured according to the method described in JIS K <NUM>.

A prepared polyol composition was charged into a sealed container of <NUM> and was left at rest at <NUM> for <NUM> days, and then the presence or absence of separation was visually checked.

As shown in Comparative Example <NUM> in Table <NUM>, when the compatibilizing agent <NUM> is not used, compatibility cannot be sufficiently improved, and separation results in occurring within <NUM> days. In addition, as shown in Comparative Example <NUM>, even though a polyether polyol has been used which has a specific range of oxyethylene units and a specific amount of a primarization ratio of terminal ends, the improvement of the compatibility between the hydrophilic component and the hydrophobic component in the polyol composition blended with a large amount of water is insufficient, and the polyol composition results in being separated within <NUM> days. In addition, as shown in Comparative Examples <NUM> to <NUM>, even when a nonionic surfactant has been used as a compatibilizing agent and an anionic surfactant which does not have an alkali metal salt in the hydrophilic portion have been used, the stability over times of the polyol composition is poor, and the separation results in occurring within <NUM> days.

As shown in Examples <NUM> to <NUM> and <NUM> to <NUM> in Table <NUM>, when flexible polyurethane foams have been produced by use of the polyol compositions of Examples <NUM> to <NUM> and <NUM> to <NUM>, it is possible to obtain a molded body of which the apparent density is less than <NUM>/m<NUM>, of which the <NUM>% compression hardness of a foam test piece provided with a skin is <NUM> to <NUM> N/<NUM><NUM>, of which the coefficient of hysteresis loss is less than <NUM>%, and of which the wet heat compression strain is less than <NUM>%.

Incidentally, as for the polyol compositions shown in Comparative Examples <NUM> to <NUM>, the flexible polyurethane foam is not produced, because the polyol compositions do not satisfy the stability over time.

In addition, as shown in Reference Example <NUM>-<NUM> of Table <NUM>, it is understood that when the toluene diisocyanate-based polyisocyanate is used as the isocyanate component, there is the case where the value of wet heat compression strain results in deteriorating. In addition, as shown in Reference Examples <NUM>-<NUM> to <NUM>-<NUM>, it is understood that a flexible polyurethane foam having adequate moldability is not obtained, depending on the rate of MDI content and the rate of isomer content of the polyphenylene polymethylene polyisocyanate.

The flexible polyurethane foam obtained by the present invention is extremely useful for achieving both the performance and the weight reduction of a flexible foam for a seat cushion and a seat back for automobiles.

Claim 1:
A polyol composition for molding a flexible polyurethane foam, comprising:
a polyol component (A);
a catalyst (B);
a foam stabilizer (C);
a foaming agent (D); and
a compatibilizing agent (E),
wherein the compatibilizing agent (E) is an anionic surfactant having a sodium salt of a naphthalenesulfonic acid formalin condensate, and
wherein the compatibilizing agent (E) is contained in an amount of <NUM> to <NUM> mass% with respect to the polyol component (A).