JP2016033213A - Polyisocyanate composition for flexible polyurethane foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyisocyanate composition that shows low hysteresis loss in a flexible polyurethane foam in a low-density area.SOLUTION: A polyisocyanate composition for a flexible polyurethane foam is provided in which a polyphenylene polymethylene polyisocyanate (A) is composed of a modified polyphenylene polymethylene polyisocyanate (C) urethane-modified with a polyol (B). The polyphenylene polymethylene polyisocyanate (A) contains diphenylmethane diisocyanate in the range of 65 to 90 mass%, and an amount of 2,2'-diphenylmethane diisocyanate and of 2,4'-diphenylmethane diisocyanate contained in the diphenylmethane diisocyanate is 10 to 50 mass% relative to a total amount of the diphenylmethane diisocyanate. The polyol (B) contains 65 mass% or more of polyoxyethylene units and has an average number of functional groups of 1.7 to 2.4. The modified polyphenylene polymethylene polyisocyanate (C) has an isocyanate content of 29 to 32 mass%.SELECTED DRAWING: None

Description

  The present invention relates to an isocyanate composition for a flexible polyurethane foam and a flexible polyurethane foam comprising the same composition. In particular, the flexible polyurethane foam of the present invention is suitable for a vehicle seat cushion that requires durability.

  For a long time, a flexible polyurethane foam for automobile seat cushions (hereinafter referred to as a flexible foam) has been required to have high durability so that a change in the viewpoint of the driver due to a decrease in thickness is reduced even when the passenger rides for a long time. On the other hand, in recent seat cushions, in order to reduce vibration transmitted from the road surface, it is required to suppress the resilience modulus of the foam low and to reduce the foam density as much as possible from the viewpoint of cost reduction. However, these low resilience and low density are known to significantly deteriorate foam durability, and establishment of a technology that achieves both durability, ride comfort and economy has been demanded.

  As a means for solving these problems, Japanese Patent Application Laid-Open No. 2001-137077 proposes a flexible foam using a mixture of tolylene diisocyanate (hereinafter TDI) and polyphenylene polymethylene polyisocyanate (hereinafter Poly-MDI). However, it is known that the flexible foam made mainly of TDI has a higher impact resilience than the flexible foam made mainly of MDI, and should be reduced to achieve sufficient vibration absorption performance. The rate range is large. As means for lowering the impact resilience, it is known to reduce the crosslink density of the resin, increase the glass transition temperature, reduce the air permeability of the foam, etc., all of which are known to deteriorate the durability of the flexible foam. As a flexible foam mainly composed of TDI, it is impossible to achieve both good vibration absorption due to low rebound resilience and high durability due to low hysteresis loss. Furthermore, the urethane foam using TDI has a large density difference between the skin layer and the core layer of the foam, and even with the same 25% compression hardness and hysteresis loss rate, the surface feel is hard and the ride performance is poor. . In addition, the use of high vapor pressure TDI is known to degrade the working environment at the flexible foam manufacturing site.

  On the other hand, compared with TDI-based flexible foams, MDI-based flexible foams generally having low rebound resilience are relatively easy to achieve both vibration absorption and durability in a high-density region. However, MDI isocyanate, which has a lower isocyanate group content (NCO content) per unit weight than TDI, requires a large amount of water to be reduced in density, and is less than 55 kg / m3, which is required for seat cushions these days. In the low-density region, the increase in the rigid urea bond generated by the reaction of isocyanate and water reduces the resilience from deformation of the resin, resulting in poor durability and a good texture characteristic of MDI foam. Lost. So far, no MDI-based flexible foam having a hysteresis loss rate of less than 28%, which is an index of durability in the density region, has been known.

  In addition, WO 2000/008083 does not contain a modified content containing diphenylmethane diisocyanate content of 81 to 100%, 2,2′-diphenylmethane diisocyanate in diphenylmethane diisocyanate and 40 to 60% of 2,4′-diphenylmethane diisocyanate. A method of reacting MDI with a polyol composition comprising a polyether polyol containing at least 60% by weight oxyethylene groups with an average nominal hydroxyl functionality of 2-6 and an average equivalent weight of 200-600 is disclosed. However, in this method, the other active hydrogen group-containing compound including water and the polyol having the oxyethylene unit compete with each other to react with the isocyanate, and as a result, the reaction of the terminal hydroxyl group of the polyol having the oxyethylene unit is completed. It is considered that there is no sufficient effect of reducing the hysteresis loss rate.

JP 2001-137077 A International Publication No. 2000/008083

The present invention relates to an isocyanate composition for producing a flexible foam, which has a good vibration absorbing property due to a low rebound resilience, and realizes a low hysteresis loss rate even in a low density region of less than 55 kg / m ³ , and the isocyanate composition It is an object of the present invention to provide a method for producing a flexible polyurethane foam using

  The present invention has been found as a result of intensive studies to solve the above-described problems.

  That is, this invention is shown in either of the following (1)-(6).

(1) A polyisocyanate composition comprising a modified polyphenylene polymethylene polyisocyanate (C) in which the polyphenylene polymethylene polyisocyanate (A) is urethane-modified with a polyol (B),
The polyphenylene polymethylene polyisocyanate (A) contains diphenylmethane diisocyanate in the range of 65 to 90% by mass, and the amount of 2,2′-diphenylmethane diisocyanate and 2,4′-diphenylmethane diisocyanate contained in the diphenylmethane diisocyanate is the diphenylmethane diisocyanate. 10 to 50% by mass relative to the total amount of
The polyol (B) contains 65% by mass or more of polyoxyethylene units, the average number of functional groups is 1.7 to 2.4, and the isocyanate content of the modified polyphenylene polymethylene polyisocyanate (C) is 29 to 32 masses. %, Polyisocyanate composition for producing flexible polyurethane foam.

  (2) The polyisocyanate composition for flexible polyurethane foam according to the above (1), wherein the freezing point of the polyol (B) at atmospheric pressure is in the range of 10 to 45 ° C.

(3) The amount of 2,2′-diphenylmethane diisocyanate and 2,4′-diphenylmethane diisocyanate contained in the diphenylmethane diisocyanate is 10 to 10% based on the total amount of diphenylmethane diisocyanate. 50% by weight of polyphenylene polymethylene polyisocyanate (A),
A polyol (B) containing 65% by mass or more of polyoxyethylene units and having an average number of functional groups of 1.7 to 2.4 is reacted so that the isocyanate content is 29 to 32% by mass. The manufacturing method of the polyisocyanate composition for flexible polyurethane foam manufacture as described in said (1) or (2).

  (4) Of the modified polyisocyanate composition (C), polyol (G), catalyst (H), water (I) as a blowing agent, and foam stabilizer (J) according to (1) or (2) above A method for producing a flexible polyurethane foam, which comprises foaming by reacting a mixed solution.

  (5) The method for producing a flexible polyurethane foam according to the above (4), wherein the polyol (G) contains a polyether polyol having a hydroxyl value of 20 to 40 mgKOH / g and an average functional group number of 2 to 4.

(6) The apparent density of the resulting flexible polyurethane foam is less than 55 kg / m ³ , the 25% compression hardness of the foamed test piece with skin is 100 to 400 N / 314 cm ² , the rebound resilience is 45 to 65%, and the hysteresis loss rate Is less than 28%, The method for producing a flexible polyurethane foam according to the above (4) or (5).

  According to the composition for molding a flexible foam containing the isocyanate composition for producing the flexible foam of the present invention, a low hysteresis loss rate is realized even in a low density region while having a good vibration absorption due to a low rebound resilience. Flexible foam can be produced.

  First, the polyisocyanate composition of the present invention will be described.

The polyisocyanate composition of the present invention is a polyisocyanate composition comprising a modified polyphenylene polymethylene polyisocyanate (C) in which the polyphenylene polymethylene polyisocyanate (A) is urethane-modified with a polyol (B),
The polyphenylene polymethylene polyisocyanate (A) contains diphenylmethane diisocyanate in the range of 65 to 90% by mass, and the amount of 2,2′-diphenylmethane diisocyanate and 2,4′-diphenylmethane diisocyanate contained in the diphenylmethane diisocyanate is the diphenylmethane diisocyanate. 10 to 50% by mass relative to the total amount of
The polyol (B) contains 65% by mass or more of polyoxyethylene units, the average number of functional groups is 1.7 to 2.4, and the isocyanate content of the modified polyphenylene polymethylene polyisocyanate (C) is 29 to 32 masses. %.

  The polyphenylene polymethylene polyisocyanate (A) in the present invention includes diphenylmethane diisocyanate (MDI) containing two benzene rings and two isocyanate groups, a polynuclear body containing three or more benzene rings and three isocyanate groups, and a commercially available polyphenylene polymethylene polyisocyanate. A small amount of impurities generally contained in isocyanate (Poly-MDI) (for example, dimer of isocyanate, methylated product or chlorinated product of Poly-MDI, carbodiimide or uretonimine compound).

  The mass content of MDI in Poly-MDI (A) (hereinafter referred to as MDI content) is Poly-MDI obtained by removing polyol (B) having a polyoxyethylene unit from the composition basic unit of modified polyphenylene polymethylene polyisocyanate (C). It is the content rate of MDI with respect to (A), and can be measured with a gel permeation chromatograph or a gas chromatograph. Further, when preparing Poly-MDI (A) by blending various kinds of MDI and polynuclear bodies, it can be calculated by calculation if the MDI content of each raw material is known in advance. As MDI content rate, 65-90 mass% is preferable, and 70-85 mass% is more preferable.

  When the MDI content according to the present invention exceeds 90% by mass, the storage stability at low temperatures of the resulting polyisocyanate composition and the durability and hardness of the resulting flexible foam are lowered. On the other hand, if it is less than 65% by mass, the crosslinking density becomes too high, the foam becomes hard to the extent that it is not suitable for a seat cushion, the elongation at break of the foam is reduced, and the foam strength sufficient for a soft foam for vehicle seats Can not get.

  Furthermore, the sum of the content of 2,2′-diphenylmethane diisocyanate (hereinafter 2,2′-MDI) and the content of 2,4′-diphenylmethane diisocyanate (hereinafter 2,4′-MDI) relative to the total amount of MDI (hereinafter referred to as isomer) The content) is required to be 10 to 50% by mass, and more preferably 20 to 45% by mass.

  If the content of 2,2′-MDI and 2,4′-MDI is less than 10% by mass based on the total amount of MDI according to the present invention, the storage stability at low temperatures of the resulting polyisocyanate composition is impaired, In addition to constant heating inside the piping and foam molding machine, the molding stability of the flexible foam is impaired, and foam collapse occurs during foaming. On the other hand, if it exceeds 50% by mass, the foam hardness is lowered, and sufficient hardness cannot be secured as a seat cushion, seat back or saddle, the reactivity is lowered, the molding cycle is extended, and the foam has a high foam rate. This causes problems such as an increase in the hysteresis loss rate.

  The polyol (B) having a polyoxyethylene unit used for the synthesis of the polyisocyanate composition of the present invention needs to have at least a polyoxyethylene unit content of 65 to 100% by mass, and 75 to 100%. Is more preferable. The polyol (B) has an average functional group number of 1.7 to 2.4, more preferably 1.9 to 2.2.

  In the present invention, when the poly-MDI (A) is urethane-modified with the polyol (B) having a specific polyoxyethylene unit content and the average number of functional groups of the polymerization initiator, the resin is formed into a flexible foam. Electrostatic interaction occurs between the polyoxyethylene units in the inside or between the polyoxyethylene units and the urethane bond or urea bond, and even if the foam has a low impact resilience due to the pseudo-crosslinked structure It achieves a hysteresis loss rate and high durability. In the modifying polyol having a polyoxyethylene unit content of less than 65%, the interaction is not sufficient, and a good effect cannot be obtained.

  When the average number of functional groups is less than 1.7, the chemical crosslinking density in the flexible foam resin is lowered, and even if the pseudo-crosslinking exists, the hysteresis loss rate and durability are insufficient. On the other hand, when the average number of functional groups exceeds 2.4, it is possible to keep the hysteresis loss rate low and improve the durability, but the elongation rate is centered compared to the case where the pseudo-crosslinking is increased. Such a foam that easily breaks due to a significant decrease in mechanical strength is not preferable for applications such as automobile seat cushions, seat backs, and saddles where passengers always get on and off. The average number of functional groups of the polyol referred to here is a numerical value on the assumption that the average number of functional groups of the polymerization initiator does not change even after polymerization. When a plurality of polyols are mixed, the molecular weight of each polyol The number of moles is calculated from the blending amount, and the product of the number of moles and the average number of functional groups of the polymerization initiator is calculated for each polyol, which means a value obtained by adding all polyols and dividing by the sum of moles of each polyol. .

  The polyol (B) can realize the good flexible foam performance of the present invention by satisfying the above-mentioned polyoxyethylene unit content and the average number of functional groups of the polymerization initiator. Among them, the polyol (B) When the freezing point is in the range of 10 to 45 ° C., more preferably 20 to 40 ° C., more excellent results are obtained. A polyol having a freezing point of 10 ° C. or higher has a high cohesive force among the polyols satisfying the polyoxyethylene unit content and the average number of functional groups of the polymerization initiator, and has a large effect of improving the hysteresis loss rate. When the freezing point exceeds 45 ° C, the cohesiveness by the polyoxyethylene unit becomes very high, and the effect of improving the hysteresis loss rate becomes larger, but the cohesive force that is too high increases the freezing point of the isocyanate itself, and is stable at low temperature storage May cause sexual deterioration.

  The freezing point is a crystallized crystal after visually storing the polyol in a glass bottle with a 100 ml lid at each temperature for 24 hours in a thermostatic water bath that has been adjusted to the correct temperature by a calibrated mercury thermometer. Refers to the highest temperature that can be confirmed.

  Furthermore, in the polyol (B) having a polyoxyethylene unit according to the present invention, the CPR value (controlled polymerization rate) defined by JIS K 1557 is preferably 10 or less. More preferably, it is 5 or less. When the CPR value exceeds 10, in the urethane modification of isocyanate, trimerization, allophanate formation, dimerization reaction other than urethanization reaction is promoted, and the isocyanate during synthesis is solidified or the isocyanate viscosity is unexpectedly increased. And it will not be practical.

  The polyol (B) containing 65 to 100% by mass of the polyoxyethylene unit according to the present invention has its freezing point within the range of the average molecular weight, etc. from the molecular weight distribution, the size and degree of dispersion of the polyoxyethylene unit, the degree of branching, etc. Although it is difficult to specify simply, in the case of a commercially available polyol having an oxyethylene unit content of 65 to 100% by mass and an average functional group number of the polymerization initiator of 1.7 to 2.4, the average molecular weight is generally 600 or more, 300 or less is a suitable range. Examples of available products include PEG-600 and PEG-1000 manufactured by Sanyo Chemical Industries, Ltd., Unilube 75DE-15 manufactured by NOF Corporation, and the like.

  Further, two or more kinds of polyols can be mixed and used as long as the content of the polyoxyethylene unit, the freezing point, the average number of functional groups, and the CPR value can be achieved.

  The isocyanate group content (NCO content) in the modified polyphenylene polymethylene polyisocyanate (C) of the present invention is 29 to 32% by mass. When the NCO content is less than 29% by mass, the amount of carbon dioxide generated by the reaction between isocyanate and water is too small to ensure moldability in the low density region. When it exceeds 32% by mass, the amount of polyol having an oxyethylene glycol unit is too small, and the hysteresis loss rate reduction effect of the present invention cannot be sufficiently obtained.

  The synthesis method in which the Poly-MDI (A) and the polyol (B) having a polyoxyethylene unit are reacted so that the isocyanate content is 29 to 32% by mass is not particularly limited. A method in which the polyol (B) having a polyoxyethylene unit in Poly-MDI is charged in its entirety and prepolymerized, a method in which a part of MDI is reacted with the polyol, and the remaining Poly-MDI is mixed can be applied.

Next, the manufacturing method of the flexible foam of this invention is demonstrated. The method for producing a flexible foam of the present invention comprises mixing the modified polyisocyanate composition (C), polyol (G), catalyst (H), water (I) as a foaming agent, and foam stabilizer (J) of the present invention. It is characterized by reacting and foaming a liquid. According to the method for producing a flexible foam of the present invention, the apparent density is less than 55 kg / m ³ , the 25% compression hardness of the foamed test piece with skin is 100 to 400 N / 314 cm ² , the rebound resilience is 45 to 65%, and the hysteresis loss. A flexible foam with a rate of less than 28% is obtained.

  The apparent density and rebound resilience are the methods described in JIS K6400, the 25% compression hardness of the test piece foam with skin is the B method described in JIS K6400, and the hysteresis loss rate is the B method described in JIS K6400. Refers to the value being measured.

  The polyol (G) according to the present invention is preferably a polyol (G) mainly composed of a polyether polyol having a hydroxyl value of 20 to 40 mg KOH / g and an average functional group number of 2 to 4 that easily exhibits excellent performance as a flexible foam.

  As such a polyether polyol, known ones can be used. For example, ethylene oxide, a low molecular weight polyol having a molecular weight of less than 700, a low molecular weight polyamine, a low molecular weight amino alcohol, etc. Examples include those obtained by adding alkylene oxides such as propylene oxide and cyclic ethers such as tetrahydrofuran. Such initiators include water, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1, 5-pentanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonane Diol, 2,2-diethyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl -1,3-hexanediol, 2-n-hexadecane-1,2-ethylene glycol, 2-n-eicosane-1,2-ethylene glycol, 2-n Octacosane-1,2-ethylene glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanedimethanol, ethylene oxide or propylene oxide adduct of bisphenol A, hydrogenated bisphenol A, 3-hydroxy-2,2-dimethylpropyl- Low molecular weight polyols such as 3-hydroxy-2,2-dimethylpropionate, trimethylolpropane, glycerin, pentaerythritol; aniline, ethylenediamine, propylenediamine, toluenediamine, metaphenylenediamine, diphenylmethanediamine, xylylenediamine, etc. Low molecular weight amines; low molecular weight amino alcohols such as monoethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine Kind, and the like.

  When the hydroxyl value exceeds 40 mgKOH / g, the hardness of the polyurethane foam becomes too high and the flexibility is also lowered. On the other hand, if the hydroxyl value is less than 20 mgKOH / g, the hardness of the polyurethane foam obtained is too soft for a vehicle seat soft foam, and poor mixing due to high viscosity is likely to occur.

  In the method for producing a flexible foam of the present invention, for the purpose of adjusting the hardness, a polymer polyol produced by polymerizing a vinyl monomer in a polyol by an ordinary method can be used in combination. Examples of such a polymer polyol include those obtained by polymerizing a vinyl monomer in the presence of a radical initiator in the same polyether polyol as the polyol (G) and stably dispersing it. Examples of the vinyl monomer include acrylonitrile, styrene, vinylidene chloride, hydroxyalkyl, methacrylate, and alkyl methacrylate. Among them, acrylonitrile and styrene are preferable. Specific examples of such a polymer polyol include EL-910 and EL-923 manufactured by Asahi Glass Urethane Co., Ltd. and FA-728R manufactured by Sanyo Chemical Industries.

  As the catalyst (H) used in the present invention, various urethanization catalysts and trimerization catalysts known in the art can be used. Representative examples include triethylamine, tripropylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, dimethylbenzylamine, N, N, N ′, N′-tetramethylhexamethylenediamine, N, N, N ′, Tertiary amines such as N ′, N ″ -pentamethyldiethylenetriamine, triethylenediamine, bis- (2-dimethylaminoethyl) ether, 1,8-diaza-bicyclo (5,4,0) undecene-7, dimethylethanol Reactive tertiary amines such as amines, N-trioxyethylene-N, N-dimethylamine, N, N-dimethyl-N-hexanolamine or organic acid salts thereof, 1-methimidazole, 2-methylimidazole, 1 , 2-dimethylimidazole, 2,4-dimethylimidazole, 1-butyl-2 Imidazole compounds such as methylimidazole, organometallic compounds such as stannous octoate, dibutyltin dilaurate, zinc naphthenate, 2,4,6-tris (dimethylaminomethyl) phenol, 2,4,6-tris (dialkylaminoalkyl) ) Trimerization catalysts such as hexahydro-S-triazine, potassium acetate, potassium 2-ethylhexanoate and the like. The type and amount of the catalyst are not particularly limited as long as they can achieve a suitable foam cell foaming rate and production cycle. However, a preferable addition amount is 0. 1 to 5 parts by mass.

  The blowing agent (I) used in the present invention is preferably a carbon dioxide gas generated by a reaction between an isocyanate group and water, and the amount of water is preferably 2 to 15 parts by mass with respect to 100 parts by mass of the polyol (G). In addition to water, liquefied carbon dioxide can be added in a range of up to 6 parts by mass to increase the expansion ratio.

  The foam stabilizer (J) used in the present invention is an organosilicon surfactant known in the art, for example, SZ-1327, SZ-1325, SZ-1336, SZ- manufactured by Toray Dow Corning. 3601, Y-10366 and L-5309 manufactured by Momentive, B-8724LF2 and B-8715LF2 manufactured by Evonik, and F-122 manufactured by Shin-Etsu Chemical. The amount of these foam stabilizers is preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the polyol (G).

  In addition, a crosslinking agent such as diethanolamine or triethanolamine can be added to the present invention for the purpose of improving molding stability and adjusting foam hardness. A preferable addition amount of the crosslinking agent is up to 5 parts by mass with respect to 100 parts by mass of the polyol (G). When the crosslinking agent is added more than necessary, strong foaming properties are produced, or the mechanical strength is deteriorated due to an increase in the crosslinking density.

  In addition to the above, flame retardants, plasticizers, antioxidants, ultraviolet absorbers, colorants, various fillers, internal mold release agents, and other processing aids can be used as additives. Of these auxiliaries, those that do not have an active hydrogen group capable of reacting with isocyanate can be mixed with polyisocyanate in advance and used.

  The molar ratio (NCO / NCO reactive group) at the time of mixed foaming of all isocyanate groups in the polyisocyanate composition of the present invention and all isocyanate reactive groups in the isocyanate reactive compound containing water is 0.7 to 1. .4 (isocyanate index (NCO INDEX) = 70 to 140), and 0.8 to 1.3 (isocyanate index (NCO INDEX) = 80 to 130 as a good range of the durability and molding cycle of the foam. ) Is more preferable.

  If the isocyanate index is less than 70, the durability is lowered and the foam is excessively increased. If it is higher than 140, the unreacted isocyanate remains for a long time, the molding cycle is extended, and the foaming is delayed due to the high molecular weight. Cell collapse occurs.

  The method for producing a flexible foam of the present invention comprises a mixed liquid of the modified polyisocyanate composition (C), polyol (G), catalyst (H), water (I) as a foaming agent, and foam stabilizer (J). A method for producing a flexible polyurethane mold foam (hereinafter referred to as “soft mold foam”) can be used, which is characterized by injecting a foaming stock solution into a mold and then foaming and curing.

  The mold temperature when the foaming stock solution is poured into the mold is usually 30 to 80 ° C, preferably 45 to 65 ° C. When the mold temperature at the time of pouring the foaming stock solution into the mold is less than 30 ° C., it leads to the extension of the production cycle due to a decrease in the reaction rate, whereas when it is higher than 80 ° C., the reaction between the polyol and the isocyanate When the reaction between water and isocyanate is excessively promoted, the foam collapses during foaming, and durability and foam feel deteriorate due to local increase of urea bonds.

  The curing time when the foaming stock solution is foam-cured is 10 minutes or less, preferably 7 minutes or less in consideration of the production cycle of general vehicle seat pads, saddles and the like.

When the flexible mold foam of the present invention is produced, each of the above components can be mixed using a high pressure foaming machine, a low pressure foaming machine or the like, as in the case of a normal flexible mold foam.
The polyisocyanate component and the polyol component are preferably mixed immediately before foaming. The other components can be mixed in advance with the polyisocyanate component or the polyol component in such a range that does not affect the storage stability of the raw materials and the change with time of the reactivity. These mixtures may be used immediately after mixing or may be used in appropriate amounts after storage. In the case of a foaming apparatus having a structure capable of simultaneously introducing more than two components into the mixing part, polyols, foaming agents, polyisocyanates, catalysts, foam stabilizers, additives and the like can be individually introduced into the mixing part.
The mixing method may be either dynamic mixing in which mixing is performed in the machine head mixing chamber of the foaming machine or static mixing in which mixing is performed in the liquid feeding pipe, or both may be used in combination. Mixing of a gaseous component such as a physical foaming agent and a liquid component is often performed by static mixing, and mixing of components that can be stably stored as a liquid is often performed by dynamic mixing. The foaming apparatus used in the present invention is preferably a high-pressure foaming apparatus that does not require solvent cleaning of the mixing part.

  The liquid mixture obtained by such mixing is discharged into a mold (mold), foamed and cured, and then demolded.

  In order to perform the demolding smoothly, it is also preferable to apply a release agent to the mold in advance. As the release agent to be used, a release agent usually used in the field of molding processing may be used.

  Although the product after demolding can be used as it is, it is preferable to stabilize the appearance and dimensions of the product thereafter by destroying the cell membrane of the foam under compression or reduced pressure by a conventionally known method.

  A suitable flexible foam by the polyisocyanate composition of the present invention has an apparent density measured by the method of JIS K6400 of less than 55 kg / m3, and 25% compression of a skinned foam specimen measured by the method B of JIS K6400. The hardness is 100 to 400 N / 314 cm 2, the rebound resilience described in JIS K6400 is 45 to 65%, and the hysteresis loss rate according to the B method described in JIS K6400 is less than 28%. If it is a flexible foam using the polyisocyanate composition by this invention, the flexible foam which has this characteristic can be easily manufactured using the said generally available raw material.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. Unless otherwise specified, “part” and “%” in the text are based on mass.

[Isocyanate Synthesis Example I-1]
Capacity with stirrer, thermometer, condenser and nitrogen gas inlet tube: 1 L reactor, 2,2′-diphenylmethane diisocyanate (2,2′-MDI): 1.4%, 2,4′-diphenylmethane Diisocyanate (2,4′-MDI): Diphenylmethane diisocyanate (MDI) containing 43.4%: 658.1 g was charged and heated to 75 ° C., and then polyol B1 (average functional group number 2 number average molecular weight 1,000, 25.6 g of ethylene oxide unit content 100%, freezing point 37 ° C., Sanyo Chemical Industries, Ltd. (PEG-1000) was charged, and urethanation reaction was performed for 2 hours while uniformly mixing with a stirring blade while maintaining the temperature. Subsequently, 316.4 g of polyphenylene polymethylene polyisocyanate (Poly-MDI) having an MDI of 39% and a content of 2,2′-MDI and 2,4′-MDI in MDI of 2.5% was charged for 30 minutes. After stirring, the mixture was cooled to room temperature to obtain an isocyanate group-terminated prepolymer “I-1” (NCO content 31.6%). The composition of Poly-MDI, which is the sum of MDI charged before the reaction with PEG-1000 and Poly-MDI charged after the reaction, is 80.2% MDI content, 2,2′-MDI in MDI and 2 , 4′-MDI was 38.1% in total.

  The method of reacting MDI and the polyol carried out in Synthesis Example 1 in advance and then adding Poly-MDI is referred to as Synthesis Method 1.

[Isocyanate Synthesis Example I-2]
MDI containing 2,2′-MDI: 0.7%, 2,4′-MDI: 24.2% in a 1 L reactor with stirrer, thermometer, condenser and nitrogen gas inlet tube: 660.1 g, MDI: 39%, 2,2′-MDI in MDI and Poly-MDI having a content of 2,4′-MDI of 2.5%: 317.4 g were charged and stirred. The composition of Poly-MDI that became uniform by stirring was 80.2% MDI content, and the total content of 2,2'-MDI and 2,4'-MDI in MDI was 21.2%. It was. Then, after raising the temperature to 75 ° C., 22.5 g of polyol B2 (average functional group number 2 number average molecular weight 600, ethylene oxide unit content 100%, freezing point 15 ° C., PEG-600 manufactured by Sanyo Chemical Industries, Ltd.) While maintaining the temperature, the urethanization reaction was carried out for 2 hours while uniformly mixing with a stirring blade. Thereafter, the mixture was cooled to room temperature to obtain an isocyanate group-terminated prepolymer “I-2” (NCO content 31.7%).

  The method of mixing MDI and Poly-MDI carried out in Synthesis Example 2 in advance and then reacting with polyol is referred to as Synthesis Method 2.

<Storage stability test>
The isocyanate-terminated terminal prepolymers I-1 to 12, R-1 to R-8, and R-10 were each stored under a temperature condition of 5 ° C., and it was confirmed whether the appearance was visually changed within 2 weeks. The case where it was considered that a problem in commercial production of the flexible foam due to turbidity, crystal precipitation, crystal precipitation, etc. was evaluated as x, and the case where there was no change and the stability was good. The x mark was not subjected to the subsequent foaming test.

[Isocyanate synthesis example: Tables 1-3]
The composition, synthesis method and details of the modifying polyol used are shown in the table.

＊１ オキシエチレン単位の含量

* 1 Content of oxyethylene units

＊１ オキシエチレン単位の含量

* 1 Content of oxyethylene units

＊日本ポリウレタン工業株式会社製 コロネート １０２１（ＴＤＩ／Ｐｏｌｙ−ＭＤＩ＝８０／２０）
＊１ オキシエチレン単位の含量

* Nippon Polyurethane Industry Co., Ltd. Coronate 1021 (TDI / Poly-MDI = 80/20)
* 1 Content of oxyethylene units

[Polyol premix adjustment]
In a mixer having a capacity of 100 L equipped with a stirrer, the polyol (G), the catalyst (H), the water (I) as the foaming agent, and the foam stabilizer (J) were charged in the amounts shown in Table 5, respectively. Mixed.

<Polyol G>
Polyol G-1: Polyoxyethylene polyoxypropylene polyol having a polymerization initiator average functional group number of 3.0 and a hydroxyl value of 28 (mg KOH / g), Sannix FA-921 manufactured by Sanyo Chemical Industries, Ltd.
Polyol G-2: polymerization initiator average functional group number = 3.0, hydroxyl value = 34 (mg KOH / g) polyoxyethylene polyoxypropylene polyol, Sanyo Chemical Industries, Ltd. Sannics FA-703
Polyol G-3: Polyoxyethylene polyoxypropylene polyol having a polymerization initiator average functional group number of 4.0 and a hydroxyl value of 28 (mgKOH / g), Exenol 838 manufactured by Asahi Glass Co., Ltd.
Polyol G-4: polymerization initiator average functional group number = 3.0, hydroxyl value = 48 (mgKOH / g), polyoxyethylene polyoxypropylene polyol, Sanyo Chemical Industries, Ltd. Sannics FA-103
Polyol G-5: Polymer polyol having an average number of functional groups = 3.0 and a hydroxyl value = 28 (mgKOH / g), Sannix FA-728R manufactured by Sanyo Chemical Industries, Ltd.
<Catalyst H>
Catalyst H-1: 33% dipropylene glycol solution of triethylenediamine, TEDA-L33 manufactured by Tosoh Corporation
Catalyst H-2: 70% dipropylene glycol solution of bis (2-dimethylaminoethyl) ether, TOYOCAT-ET manufactured by Tosoh Corporation
<Foam stabilizer J>
Foam stabilizer J-1: Silicone foam stabilizer, B-8715LF2 manufactured by Evonik
Foam stabilizer J-2: Silicone foam stabilizer, E-8onic B-8724LF2.

[Form molding]
[Foaming conditions]
Mold temperature: 55-60 ° C
Mold shape: 100 × 300 × 300mm
Mold material: Aluminum Cure condition: 55-60 ° C x 4 minutes

  Examples of flexible foam molded products K-1 to K-8

  Examples of flexible foam molded products K-9 to K-12, Comparative examples K-13 to K-16

  Comparative Examples of Flexible Foam Molded Products K-17 to K-22

  The isocyanate group terminal prepolymers I-1 to 12 synthesized with the polyol premixes P-1 to P7 were adjusted to a liquid temperature of 25 ± 1 ° C. Isocyanate group-terminated prepolymers I-1 to 12 are mixed with the polyol premix at the ratio of the isocyanate index values shown in Tables 6 and 7, mixed for 7 seconds with a mixer (7000 rpm), and injected into the mold. After foaming the flexible foam, the flexible foam was taken out from the mold, and after the foam was broken by roller crushing, the physical properties of the obtained flexible foam were measured.

  Polyol premixes P-1 to P-7, synthesized isocyanate group-terminated prepolymers R-1 to R-8, and commercially available TDI / MDI blend isocyanate were adjusted to a liquid temperature of 25 ± 1 ° C. Polyisocyanate group-terminated prepolymers R-1 to R-8 and TDI / MDI blend isocyanate are added to the polyol premix at the isocyanate index shown in Tables 7 and 8, and mixed for 7 seconds with a mixer (7000 rpm). After injecting into the mold and reacting and foaming the polyurethane foam, the polyurethane foam was taken out of the mold and bubble-breaking by roller crushing, and then the physical properties of the obtained flexible foam were measured.

<Method for measuring physical properties of polyurethane foam>
Apparent density, tensile strength, elongation, tear strength, impact resilience, wet heat compression residual strain are the methods described in JIS K6400, and compression residual strain is A method described in JIS K6400, 25% of the test piece foam with skin. The compression hardness was measured by the B method described in JIS K6400, and the hysteresis loss rate was measured by the B method described in JIS K6400.

  As is clear from the results shown in Tables 6 and 7, all of the flexible polyurethane foam Examples K-1 to K-12 obtained by the method of the present invention using the polyisocyanate composition of the present invention are oxyethylene glycol. As a result of the pseudo-crosslinking due to the aggregation of the units, it was confirmed that the hysteresis loss rate was less than 28% and good physical properties were exhibited.

  As shown in Comparative Examples K-13 and 14, in the TDI / MDI blend isocyanate generally used, the rebound elastic modulus becomes too high without special measures, and does not show good vibration absorption performance. On the other hand, when the impact resilience rate is reduced by reducing the air permeability, the hysteresis loss rate is relatively low, but the static durability is significantly deteriorated. There is a possibility that the viewpoint changes and safety problems may arise.

  In Comparative Example K-15, the set NCO content is too low, and the foam cannot be reduced to the target density.

In Comparative Example K-16, since the set NCO content is high and the amount of polyol having oxyethylene glycol units is small, the crosslinking effect due to aggregation is low, and the hysteresis loss rate is 28%.
The result exceeded.

  When the MDI content is lowered as in Comparative Example K-17 and when the number of functional groups of the modifier polyol is increased as in K-19, the chemical crosslink density in the flexible foam resin becomes too high, Although a low hysteresis loss rate and high durability can be realized, the mechanical strength of the foam deteriorates to such an extent that it cannot withstand regular use.

  When the number of functional groups of the modifier polyol is set low as in Comparative Example K-18, the chemical crosslinking density in the flexible foam resin decreases, the hysteresis loss rate increases, and the durability deteriorates.

  The modifier used in Comparative Examples K-20 to 21 has a freezing point that does not fall within the range of 10 to 45 ° C. and is liquid at room temperature. As a result, the cross-linking effect due to aggregation was low, and the hysteresis loss rate exceeded 28%.

  In Comparative Example K-22, MDI was not modified, and a modifier was mixed with a polyol premix and foamed. As a result, the hysteresis loss rate increased. Moreover, the storage stability of the polyol premix also deteriorated.

  From the above results, when the polyisocyanate composition of the present invention is used, it is possible to mold a flexible urethane foam having a density of less than 55 kg / m3 and a low hysteresis loss rate of less than 28%, which is extremely useful industrially. is there.

Claims (6)

A polyisocyanate composition comprising a modified polyphenylene polymethylene polyisocyanate (C) in which the polyphenylene polymethylene polyisocyanate (A) is urethane-modified with a polyol (B),
The polyphenylene polymethylene polyisocyanate (A) contains diphenylmethane diisocyanate in the range of 65 to 90% by mass, and the amount of 2,2′-diphenylmethane diisocyanate and 2,4′-diphenylmethane diisocyanate contained in the diphenylmethane diisocyanate is the diphenylmethane diisocyanate. 10 to 50% by mass relative to the total amount of
The polyol (B) contains 65% by mass or more of polyoxyethylene units, the average number of functional groups is 1.7 to 2.4, and the isocyanate content of the modified polyphenylene polymethylene polyisocyanate (C) is 29 to 32 masses. %, Polyisocyanate composition for producing flexible polyurethane foam. The polyisocyanate composition for flexible polyurethane foam according to claim 1, wherein the freezing point of the polyol (B) at atmospheric pressure is in the range of 10 to 45 ° C. The amount of 2,2′-diphenylmethane diisocyanate and 2,4′-diphenylmethane diisocyanate contained in the diphenylmethane diisocyanate is 10 to 50% by mass with respect to the total amount of the diphenylmethane diisocyanate. Polyphenylene polymethylene polyisocyanate (A),
A polyol (B) containing 65% by mass or more of polyoxyethylene units and having an average number of functional groups of 1.7 to 2.4 is reacted so that the isocyanate content is 29 to 32% by mass. The manufacturing method of the polyisocyanate composition for flexible polyurethane foam manufacture of Claim 1 or 2. A mixture of the modified polyisocyanate composition (C), polyol (G), catalyst (H), water (I) as a blowing agent, and foam stabilizer (J) according to claim 1 or 2 is reacted. A method for producing a flexible polyurethane foam characterized by foaming. The method for producing a flexible polyurethane foam according to claim 4, wherein the polyol (G) comprises a polyether polyol having a hydroxyl value of 20 to 40 mgKOH / g and an average functional group number of 2 to 4. The apparent density of the obtained flexible polyurethane foam is less than 55 kg / m ³ , the 25% compression hardness of the foamed test piece with skin is 100 to 400 N / 314 cm ² , the rebound resilience is 45 to 65%, and the hysteresis loss ratio is 28%. The method for producing a flexible polyurethane foam according to claim 4 or 5, wherein the number is less.