HK1138301A - Soft urethane foam and preparation method thereof - Google Patents

Description

Flexible polyurethane foam and process for producing the same

Technical Field

The present invention relates to an aromatic isocyanate-based polyurethane foam having excellent weather resistance and water washing deformation resistance, particularly suitable for clothing applications, in which an aliphatic isocyanate and/or an alicyclic isocyanate and/or an isocyanate group is not directly attached to an aromatic ring, and a method for preparing the same. It also relates to reaction systems and specific isocyanate-reactive component compositions that can be used in said process.

Background

Flexible polyurethane foams are used in a very wide range of industrial applications. They are usually prepared by reacting organic polyisocyanates with compounds containing at least two active hydrogen atoms which are reactive towards isocyanate groups in the presence of blowing agents, catalysts, siloxane-based surfactants and other additives. The active hydrogen-containing compounds are typically polyols, primary and secondary polyamines and water. Two major reactions between reactants during polyurethane foam production, gelation and foaming are promoted by catalysts. These reactions must proceed simultaneously and at a fairly balanced rate in the process to yield polyurethane foams having the desired physical properties.

Aromatic isocyanates such as Toluene Diisocyanate (TDI) and diphenylmethane diisocyanate (MDI) are widely used for preparing flexible and rigid polyurethane foams because of their high reactivity. Aliphatic or cycloaliphatic isocyanates are rarely used to make polyurethane foams because aliphatic and cycloaliphatic isocyanates are relatively less reactive than aromatic isocyanates.

Flexible polyurethane foams are widely used in apparel applications, as disclosed in us 4,250,137 issued to Riedler at 10.2.1981, which discloses a method of heating flexible polyurethane foams to a temperature above their glass transition temperature (Tg) using a high temperature mold at 400 f 350-.

The main problem of using aromatic polyurethane foam for underwear pad or shoulder pad is that the aromatic polyurethane foam generates diquinoneimine compound causing yellowing during the photo-oxidation process of irradiation or contact with air and the discoloration of the aromatic polyurethane foam is rapidly generated, which causes troubles in manufacturing and use.

Another challenge with the use of aromatic polyurethane foam underwear liners is their aromatic amine emissions. The aromatic polyurethane foam is decomposed by heat in the thermoforming process to generate corresponding aromatic amine, and in the washing process, the aromatic polyurethane foam is subjected to wet or heat aging decomposition along with the processes of washing and drying, and a urethane bond and a urea bond in the foam are hydrolyzed and broken to form corresponding aromatic amine such as Toluenediamine (TDA) and diaminodiphenylmethane (MDA).

Toluenediamine and diaminodiphenylmethane are highly toxic and potentially carcinogenic compounds of public concern, IARC (international agency for research on cancer), NTP (national regulation of toxic substances), OSHA (occupational disease and safety and health administration of the U.S. department of labor) and the like have classified such aromatic amines as class 2B carcinogen classification criteria, as "substances that are confirmed to cause carcinogenesis in animals" and "substances that are suspected or may cause carcinogenesis in humans". EUROPUR (European Flexible polyurethane foam producer Association, established in 1966) announced a voluntary project called "CertiPUR" in 2007. CertiPUR is an item that emphasizes the industry's commitment to its product security, health, and environmental (SHE) performance. To comply with the CertiPUR standard, many harmful substances are restricted or prohibited. The upper limit of the total amount of 2, 4-TDA and 4,4 '-MDA and the respective amounts of 2, 4-TDA and 4, 4' -MDA in the polyurethane foam is 5ppm by weight of the foam, according to the CertipUR standard.

Since flexible polyurethane foams have unique properties that cannot be replaced by other materials in the field of apparel applications, there is a need to develop a process for preparing flexible polyurethane foams without using aromatic isocyanates to address the concerns of weatherability, resistance to water washing deformation, and safety of aromatic amines in polyurethane foam pads. Flexible polyurethane foams based on aliphatic and/or cycloaliphatic isocyanates provide a solution to this need.

Aliphatic and cycloaliphatic isocyanates are rarely used to make polyurethane foams because of their much lower reactivity. Focusing on stronger catalysts, more reactive polyisocyanate compositions, polyol compositions employing highly reactive polyols or other production process options, only a few synthetic methods have been developed to prepare aliphatic or cycloaliphatic isocyanate-based polyurethane foams having useful physical properties.

U.S. patent application 5,147,897 issued to Morimoto et al on 9, 15, 1992 discloses a two-step process for preparing non-yellowing polyurethane foams using aliphatic polyisocyanate prepolymers. The method comprises the steps of₂-C₁₀Reacting the aliphatic polyisocyanate prepolymer with 0.4 to 5 times the isocyanate equivalent of water in the presence of a potassium or sodium salt of an alkanoic acid or a diazabicyclo olefin catalyst. The prepolymer is an aliphatic isocyanate terminated prepolymer obtained by addition polymerization of a polyol having an average molecular weight of 100-5,000 and an aliphatic polyisocyanate having a hydroxyl equivalent weight of 1.4 to 2.6 times. The method of Morimoto et al cannot be used to prepare a prepolymer having a density of less than 80kg/m due to the reduced reactivity and high viscosity of the prepolymer obtained³And, furthermore, cannot be used for the preparation of molded foams.

Japanese patent application JP 2001-21-3-2001-72738A discloses a polyurethane foam having excellent water resistance and no discoloration under sunlight, which is a low water-absorbing polyurethane foam prepared by reacting an aliphatic diisocyanate with a polyol having an ethylene oxide content of less than 18 parts by weight (based on 100 parts by weight of the total polyol alkylene oxide) in the presence of a catalyst selected from diazabicycloalkene and its phenyl salt and an alkali metal salt of a weak acid, to improve the aging characteristics of the foam after repeated washing. Although this method improves the washing distortion and the durability problems caused by the dissolution of antioxidants and light stabilizers, it requires the addition of a higher proportion of catalyst to compensate for the deficiency due to the reduced activity of the polyol used. The obvious disadvantage of this process is that the polyol used has a low content of primary hydroxyl groups and thus insufficient reactivity, and the formulation has a very narrow operating window between collapse due to insufficient reaction or shrinkage of closed cells due to an excessively high amount of catalyst during practical use, making production difficult.

Japanese patent application JP2006-257187a, published on 28.9.2006, Kurashiki Boseki corp, discloses a process for preparing a practically non-yellowing polyurethane foam for clothing, health care or cosmetics. The polyurethane foam is prepared by: reacting a polyethylene oxide-polypropylene oxide copolymer polyol with a polyisocyanate composition comprising a mixture of (isophorone diisocyanate (IPDI) and/or IPDI trimer or derivatives thereof): (trimer of Hexamethylene Diisocyanate (HDI) and/or HDI derivatives) mass adjusted to (70-30): (30-70).

Published 2008 on month 4 and 9 and chinese patent publication No. CN 101157747a discloses a method of preparing polyurethane foam using a high functional group polyethylene oxide-polypropylene oxide copolymer having an ethylene oxide content of 8 to 25 weight percent.

Japanese patent application published on 1/15/2003, JP 2003-012756A, discloses a nearly non-yellowing polyurethane foam prepared by reacting an alicyclic diisocyanate with an amine-terminated polypropylene oxide copolymer polyol. This application also describes these polyols consisting only of propylene oxide units. These amine-terminated polypropylene oxides are expensive and are available only in limited supply. It is difficult to obtain useful amine-terminated polypropylene oxide molecules to make flexible polyurethane foams.

The above-mentioned methods for preparing non-yellowing polyurethane foams all use highly reactive polyethylene oxide-polypropylene oxide copolymer or amine-terminated polypropylene oxide copolymer polyols having a high ethylene oxide content to react with low-reactive aliphatic isocyanates or alicyclic isocyanates. Such a high ethylene oxide content polyethylene oxide-polypropylene oxide copolymer or amine-terminated polypropylene oxide copolymer polyol is very easily oxidized to discolor, so that the prepared polyurethane foam has excellent light fastness, but is easily oxidized to yellow by being exposed to air, thereby affecting the practicability of the product. Another significant disadvantage of using such high ethylene oxide content polyethylene oxide-polypropylene oxide copolymer or amine-terminated polypropylene oxide copolymer polyols is their high hydrophilicity, which is very easy to absorb water to soften and swell and deform during washing, resulting in accelerated loss of the stabilizer in the foam, thereby often limiting the applicability of such non-yellowing polyurethane foams in apparel applications.

Therefore, there is a need to develop a flexible polyurethane foam having a low density and excellent weather resistance and water washing deformation resistance by reacting an aliphatic and/or alicyclic diisocyanate with a commercial product of a non-hydrophilic polyether polyol. Such foams do not emit any aromatic amine during their life cycle.

Published 2009 on 14.5.2009, dupont patent application WO 2009/061992 a1 discloses the use of poly (trimethylene ether) glycol compounds to prepare closed-cell rigid, semi-rigid polyurethane or polyisocyanurate foams, and to utilize the closed-cell character thereof to enclose a gas as a blowing agent in the cells, and further to utilize the lower thermal conductivity of the gas to improve the thermal insulation of such polyurethane or polyisocyanurate foams for use as thermal insulation.

Published 2009 on 22, chinese patent publication No. CN 101412798 discloses a process for preparing low resilience foams using two polyols with different isocyanate functionalities and hydroxyl equivalent weights in conjunction with a low isocyanate index range and further describes that the resulting low resilience foams have a ball drop resilience of less than 15%.

The present invention prepares a flexible polyurethane foam by reacting an aliphatic isocyanate and/or an alicyclic isocyanate and/or an aromatic isocyanate in which an isocyanate group is not directly bonded to an aromatic ring with an isocyanate-reactive mixture containing a polyoxyalkylene glycol compound, a blowing agent, and a catalyst. The foams produced have excellent weatherability and resistance to water washing deformation characteristics, have a density in the range of 8 to 160 kg/m, a ball rebound of greater than 20%, and are prepared at an isocyanate index of 80 to 130, preferably about 85 to 125, more preferably about 90 to 120.

Disclosure of Invention

It is an object of the present invention to provide a process for preparing flexible polyurethane foams based on the reaction product of an isocyanate-reactive component and an isocyanate component which is substantially free of aromatic isocyanates having isocyanate groups directly attached to aromatic rings and which comprises only aliphatic isocyanates and/or cycloaliphatic isocyanates and/or aromatic isocyanates having isocyanate groups not directly attached to aromatic rings.

It is another object of the present invention to provide a novel polyol composition suitable for reacting with aliphatic and/or cycloaliphatic isocyanates and/or isocyanates having isocyanate groups not directly attached to an aromatic ring and one or more catalysts, blowing agents, surfactants as cell regulators, crosslinking agents and other additives to produce flexible polyurethane foams.

It is another object of the present invention to provide a process for preparing a non-yellowing flexible polyurethane foam.

It is another object of the present invention to provide a one-step process for preparing non-yellowing flexible polyurethane foams having a relatively low density.

It is another object of the present invention to provide a process for preparing a molded flexible polyurethane foam.

It is another object of the present invention to provide a process for preparing a flexible polyurethane foam which does not produce toxic aromatic amines upon aged decomposition in hot, humid environments.

It is another object of the present invention to provide a process for preparing biodegradable polyurethane foams using renewable bio-sourced polyols.

It is another object of the present invention to provide novel flexible polyurethane foams that can be used in the field of underwear pads, shoulder pads, bed pads, pillows, furniture pads and automobile seat cushions.

One embodiment of the present invention discloses a flexible polyurethane foam. The flexible polyurethane foam of the present invention comprises the reaction product of:

a. an isocyanate component that is substantially free or free of aromatic isocyanates having isocyanate groups directly attached to aromatic rings;

b. an isocyanate reactive mixture comprising at least one polyoxyalkylene diol;

c. one or more blowing agents;

d. at least one catalyst; and

e. optionally one or more selected from the group consisting of: surfactants, cross-linking agents and additives;

wherein said foam has a density in the range of 8 to 160 kilograms per cubic meter and is prepared at an isocyanate index of 80 to 135, preferably about 85 to 130, more preferably about 90 to 125.

Optionally, the isocyanate reactive component further comprises a crosslinker having a weight average molecular weight of 60 to 420g/mol and having at least two isocyanate reactive functional groups. In one embodiment the cross-linking agent is used in an amount of from 0.2 to 15 parts by weight, most preferably from 1.2 to 12 parts by weight, based on 100 parts by weight of the isocyanate-reactive mixture.

Another embodiment of the present invention is directed to a process for preparing a flexible polyurethane foam. The process of the present invention comprises preparing a foam formulation comprising an isocyanate-reactive mixture, an isocyanate component substantially free of isocyanate groups directly attached to an aromatic ring, a blowing agent, at least one catalyst to form urethane linkages and a foam stabilizer/surfactant in the foam formulation, followed by foaming, and thereafter curing the resulting foam formulation. The isocyanate reactive blend is selected from the isocyanate reactive compositions described above.

Another embodiment of the present invention is directed to a process for preparing a flexible polyurethane foam by employing a one-shot process.

Another embodiment of the present invention is directed to a process for preparing a flexible molded polyurethane foam.

Another embodiment of the present invention relates to flexible polyurethane foams prepared by the above process and having a density of from 8 to 160 kg/m.

The isocyanate-reactive component of the present invention provides a greater range of formulation components in the preparation of flexible polyurethane foams of greater ranges of density and hardness.

The present invention relates to novel flexible polyurethane foams prepared by reacting an isocyanate component substantially free of aromatic isocyanates having isocyanate groups directly attached to aromatic rings with the disclosed isocyanate reactive component and at least one catalyst, blowing agent, optional surfactant, crosslinking agent and additives.

The isocyanate component is selected from one or more of the following isocyanates: aliphatic isocyanates, cycloaliphatic isocyanates and aromatic isocyanates in which the isocyanate groups are not directly attached to an aromatic ring. When an aromatic isocyanate in which aliphatic and/or alicyclic and/or isocyanate groups are not directly bonded to an aromatic ring is used, the present invention provides a flexible polyurethane foam having excellent processability and good foam mechanical properties. Furthermore, the present invention discloses a one-step process for preparing flexible polyurethane foams in a wide range of hardness, using only water as blowing agent.

The invention discloses a novel aliphatic or alicyclic isocyanate-based polyurethane material. The polyurethane material of the present invention is suitable for preparing a flexible polyurethane foam which can be used as a material for underwear pads, shoulder pads, and also suitable for mattresses, pillows, furniture pads, mats, and automobile seat cushions. It is particularly suitable for underwear and shoulder pads.

In the one-step process of the present invention, the formulation materials are simultaneously injected into a mixing head and then poured into a mold or onto a conveyor belt. The foaming reaction proceeds very quickly. The rising foam was substantially completely cured within 2-7 minutes depending on the catalyst used. The resulting foam was then allowed to post cure for 24 hours to obtain its final properties.

In the process of the present invention, the reaction composition comprises an isocyanate component, an isocyanate-reactive component, at least one catalyst, water as blowing agent, a surfactant, a crosslinking agent and additives. Other additives that may be used include pigments/dyes, antioxidants, UV (ultraviolet) light stabilizers, UV light absorbers, flame retardants, fillers, recycled foam powders, stabilizers, antimicrobial compounds, and antistatic agents, if desired.

The isocyanate comprises an aromatic diisocyanate monomer in which an aliphatic and/or alicyclic and/or isocyanate group is not directly attached to an aromatic ring, or a blend of an aromatic diisocyanate monomer in which an aliphatic and/or alicyclic and/or isocyanate group is not directly attached to an aromatic ring and a trimer which is a product of trimerization of an aromatic diisocyanate in which an aliphatic or alicyclic group or an isocyanate group is not directly attached to an aromatic ring, and the blend has an NCO functional group content of 20.5 to 50.0 parts by weight (based on 100 parts by weight of total isocyanate in the isocyanate component) and a calculated functionality of 2 to 3. The aromatic isocyanate in which the aliphatic or alicyclic or isocyanate group is not directly attached to the aromatic ring may be at least one selected from, but not limited to: hexamethylene diisocyanate, bicycloheptane triisocyanate, undecane diisocyanate, dodecane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, dimethylcyclohexane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, dimers and trimers thereof. Among these isocyanates, hexamethylene diisocyanate and isophorone diisocyanate are particularly preferable.

In addition to the aromatic isocyanate monomer and trimer, wherein the aliphatic and/or cycloaliphatic and/or isocyanate groups are not directly attached to the aromatic ring, the isocyanate component may optionally comprise up to 50% by weight (based on the total weight of the isocyanate component) of an aromatic isocyanate prepolymer wherein the aliphatic or cycloaliphatic or isocyanate groups comprise from 2 to 4 isocyanate functional groups which are not directly attached to the aromatic ring.

The isocyanates are generally used at the following levels: the isocyanate index is from about 80 to 135, preferably from 85 to 130, more preferably from 90 to 125. The isocyanate-reactive mixture comprises:

b. an isocyanate reactive mixture comprising at least one polyoxyalkylene diol;

one or more blowing agents (c);

at least one catalyst (d); and

optionally one or more selected from the group consisting of: surfactant, cross-linking agent and additive.

The isocyanate-reactive component of the present invention includes a wide variety of compounds. Good examples of these include, but are not limited to, the following: (a) poly (tetramethylene ether) glycol; (b) poly (trimethylene ether) glycol and (c) poly (trimethylene ether-ethylene ether) glycol. All hydroxyl groups in such polyols are highly isocyanate-reactive primary hydroxyl groups and therefore can meet the reaction rate requirements of the isocyanate component of an aliphatic isocyanate and/or cycloaliphatic isocyanate and/or an aromatic isocyanate in which the isocyanate groups are not directly attached to an aromatic ring. On the other hand, these polyols are much less hydrophilic than polyethylene oxide-polypropylene oxide copolymer polyols, so that the swelling degree of the prepared flexible polyurethane foam when immersed in water containing an alkaline detergent is greatly improved, and the loss of the antioxidant, light stabilizer and light absorber contained in the polyurethane foam after repeated washing is greatly reduced, and thus, they are particularly suitable for preparing flexible polyurethane foam for clothing having excellent water washing deformation resistance and weather resistance.

The first class of polyols of the present invention are the poly (tetramethylene ether) glycols described above. Poly (tetramethylene ether) glycol is a ring-opening polymerization product of Tetrahydrofuran (THF), such as that obtained via acid-catalyzed ring-opening polymerization of tetrahydrofuran as described in U.S. Pat. No. 5,371,276 to Chu et al, filed 12, 6, 1994. As described in patent application WO2008/115840 a2 published on 25.9.2008, 1, 4-butanediol produced by fermentation conversion of plant-based glucose is used as a raw material, and is further converted into tetrahydrofuran by dehydration reaction, and poly (tetramethylene ether) glycol can be obtained by ring-opening polymerization of this tetrahydrofuran. Such poly (tetramethylene ether) glycols derived from renewable biomass are preferred poly (tetramethylene ether) glycols of the present invention because the carbon source is the plant's carbon uptake from the air, rather than using carbon from petrochemical feedstocks, and therefore do not increase carbon emissions. Poly (tetramethylene ether) glycol is a polyether polyol, which is also known as PTMEG or polytetrahydrofuran and various trade names such as "Terathane" and "PolyTHF". The resulting polymer generally has a number average molecular weight of 250-6,000 g/mol. All of the hydroxyl groups in these poly (tetramethylene ether) glycols are primary hydroxyl groups. In the present invention, a poly (tetramethylene ether) glycol having an average molecular weight of 600-4,000, more preferably 1,000-6,000 is particularly preferred. Poly (tetramethylene ether) glycols having a molecular weight below 1,000 will make polyurethane foams produced having too high a hardness and low ball rebound resilience unsuitable for use in the present invention, while poly (tetramethylene ether) glycols having a molecular weight above 4,000 will be too viscous at room temperature due to their high melting point and are not suitable for use in the present invention.

The second class of polyols of the present invention are poly (trimethylene ether) glycols. Poly (trimethylene ether) glycols can be prepared by 1, 3-propanediol initiated oxetane ring-opening polymerization or novel multi-step continuous polycondensation reactions of 1, 3-propanediol, as described in U.S. patent 7,074,968 issued to Sunkara et al, 7, 11, 2006. 1, 3-propanediol obtained from a biomass glucose feedstock via fermentation can be used as a feed in the production process to produce renewable, biodegradable poly (trimethylene ether) glycol. These poly (trimethylene ether) glycols have primary hydroxyl groups and low melting points and high flexibility. Of the poly (trimethylene ether) glycols, those having a weight average molecular weight of 600-4,500, particularly 1,000-4,000g/mol, are most preferred for preparing flexible polyurethane foams. Another motivation for using such poly (trimethylene ether) glycols comes from their biodegradable nature.

A third class of polyols of the present invention are poly (trimethylene-ethylene ether) glycols, which are diols obtained by the polycondensation of 1, 3-propanediol and ethylene glycol in specific proportions under acid catalysis, as disclosed in 2004, 2, 12, dupont patent application US2004/0030095 a 1. The poly (trimethylene ether-ethylene ether) glycols particularly useful in the present invention comprise an ethylene ether segment content of less than 30 parts by weight, preferably from 5 to 30 parts by weight, more preferably from 5 to 20 parts by weight, based on 100 parts by weight of the poly (trimethylene ether-ethylene ether) glycol compound. An ethylene ether segment content of less than 5 parts by weight does not help to improve the compatibility of the isocyanate component and the isocyanate reactive mixture component, and an ethylene ether segment content of more than 20 parts by weight greatly increases the hydrophilicity of the prepared flexible polyurethane foam, thereby increasing the deformation rate of the flexible polyurethane foam after washing. Wherein the poly (trimethylene ether-ethylene ether) glycol compound has a weight average molecular weight of 600-5,000g/mol, preferably 1,000-4,000 g/mol. The ethylene ether may be incorporated into the interior segments, as end segments, or randomly distributed along the polyol chain, most preferably a poly (trimethylene ether-ethylene ether) glycol compound in which the ethylene ether is randomly distributed.

In one embodiment, the isocyanate-reactive component (b) is a polyoxyalkylene glycol compound of formula I

H-[O-(CH₂)_m-]_nOH (formula I)

Wherein the number m of methylene groups in each unit is independently 2, 3 or 4, or 3 or 4, and the number n of units is an integer of 14 to 90.

The crosslinker component may be OH, NH or NH-bearing₂More particularly aliphatic or alicyclic OH, NH or NH₂A crosslinking agent having at least two isocyanate reactive functional groups. Typical examples of crosslinkers used to prepare the flexible polyurethane foams of the present invention are: glycerol, 1, 1, 1-trimethylolethane, 1, 1, 1-trimethylolpropane, 1,2, 3-trimethylolhexane, poly (propylene oxide-ethylene oxide), poly (propylene oxide), poly (ethylene oxide), monoethanolamine, diethanolamine, 2-amino-2-methyl-1-propanol, and hydrazine. Mixtures of several crosslinking agents can also be used if desired.

The weight average molecular weight of the cross-linking agent is 60-420g/mol, and the cross-linking agent has at least two isocyanate reactive functional groups. In one embodiment, the crosslinking agent is used in an amount of 0.2 to 15 parts by weight, most preferably 1.2 to 12 parts by weight, based on 100 parts by weight of the isocyanate-reactive mixture.

It has surprisingly been found that of these crosslinkers, amine crosslinkers having a molecular structure of formula II are particularly useful for preparing the polyurethane foams of the present invention.

H_(3-x)-N-[(CH₂)₂-OH]_x(formula II)

Wherein x is an integer from 1 to 3.

The amine-based crosslinking agent is used in an amount of 0.2 to 8.0 parts by weight, preferably 0.4 to 6.0 parts by weight, more preferably 0.5 to 5.0 parts by weight, based on 100 parts by weight of the isocyanate-reactive mixture.

A wide variety of polyurethane catalyst commercial products are available for preparing the flexible polyurethane foams of the present invention. Catalysts are generally used at levels of 0.05 to 2.5php (parts by weight per 100 parts by weight polyol). Representative catalysts include: (1) tertiary amines such as bis (2, 2' -dimethylamino) ethyl ether, bis (dimethylaminoethyl) ether, N-methylmorpholine, N-ethylmorpholine, N-dimethylbenzylamine, N-dimethylethanolamineN, N' -tetramethyl-1, 3-butanediamine, pentamethyldipropylenetriamine, trimethylamine, triethylamine, triethanolamine, triethylenediamine, and pyridine oxide; (2) compounds containing a structure > N-C ═ N-such as diazadicyclones or guanidines, and usable compounds are 1, 5-diazabicyclo- (4, 3, 0) nonene-5, 1, 8-diazabicyclo- (5, 4, 0) undecene-7, 1, 8-diazabicyclo- (5, 3, 0) decene-7, 1, 5-diazabicyclo- (5, 4, 0) undecene-5, 1, 4-diazabicyclo- (3, 3, 0) octene-4, guanidine, 1, 3-diphenylguanidine, 1, 3, 3-tetramethylguanidine, cyclohexyltetramethylguanidine, N-dodecyltetramethylguanidine, guanidinium thiocyanate, 1, 3-di (tert-butoxycarbonyl) guanidine, 1, 3-di-tert-butoxycarbonyl-2- (2-hydroxyethyl) guanidine, 1, 5-diazabicyclo- (4, 3, 0) decene-7, 1, 5-diazabicyclo- (5, 4, 1, 3-di-tert-butoxycarbonyl-2- (carbonylmethyl) guanidine, 1, 8-bis (tetramethylguanidino) naphthalene, 1- (2, 2-diethoxyethyl) guanidine, 1- (4-methoxyphenyl) guanidine and diazabicycloalkene or an organic salt of a guanidine compound such as phenoxide, formate, acetate and carbonate; (3) strong bases such as alkali and alkaline earth metal alkoxides, hydroxides, and phenoxides; (4) acidic metal salts of acids such as stannous chloride, ferric chloride, antimony trichloride, bismuth chloride and nitrates; (5) chelates of various metals such as those obtained with acetylacetone, benzoylacetone, trifluoroacetylacetone, ethyl acetoacetate, salicylaldehyde, cyclopentanone-2-carboxylate, acetylacetoneimine, diacetone-alkylene diimine, and salicylaldimine, and various metals such as Be, Mg, Zn, Pb, Ti, Zr, Sn, Bi, Mo, Mn, Fe, Co, and Ni; (6) alkoxides and phenoxides of various metals, e.g. Sn (OR)₄、Sn(OR)₂、Ti(OR)₄And Al (OR)₃Wherein R is an alkyl or aryl group, and the reaction product of an alkoxide with a carboxylic acid, a beta-diketone and a 2- (N, N-dialkylamino) alkanol, such as a titanium chelate obtained by such or similar steps; (7) salts of organic acids with various metals such as alkali metals and alkaline earth metals such as calcium caproate, stannous acetate, stannous octoate and stannous oleate; (8) organometallic derivatives of tetravalent tin, trivalent and pentavalent As, Sb and Bi, and metal carbonyls of iron and cobalt.

Of the above catalysts, organotin compounds and stannous compounds have been found to be particularly useful in preparing the flexible polyurethane foams of the present invention. Preferred organotin compounds are the dialkyltin salts of carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dimethyltin dilaurate, dibutyltin maleate, dilauryltin diacetate, and dioctyltin diacetate. Other useful organotin compounds are trialkyltin hydroxides, dialkyltin oxides, dialkyltin dialkoxides, dialkyltin dichlorides and dialkyltin dithiols. Examples of these compounds include trimethyltin hydroxide, tributyltin hydroxide, trioctyltin hydroxide, dibutyltin oxide, dioctyltin oxide, dilauryltin oxide, dibutyltin dichloride, dioctyltin dichloride, dibutyltin dithiolate and dimethyltin dithiolate. Preferred organic stannous compounds are stannous salts of carboxylic acids, such as stannous acetate, stannous octoate, and stannous oleate. The organotin compounds or stannous compounds are generally used in amounts of from about 0.05 to 1.5% by weight, preferably from 0.15 to 1.0% by weight, based on the isocyanate-reactive mixture (b).

Compounds containing > N-C ═ N-structures, such as organic salts of diazabicycloalkenes and diazabicycloalkenes, such as phenolates, formates, acetates and carbonates, are also suitable as catalysts for preparing the flexible polyurethane foams of the present invention, and particularly effective are 1, 8-diazabicyclo- (5, 4, 0) -undecene-5 (DBU) and phenolates of DBU, said organic salts of diazabicycloalkenes and diazabicycloalkenes generally being used in amounts of from about 0.05 to 2.5% by weight, preferably from 0.1 to 1.5% by weight, based on the isocyanate-reactive mixture (b).

Another catalyst which may be used in the preparation of the flexible polyurethane foams of the present invention is a salt of a Bronsted acid with various alkali metals. Sodium bicarbonate or carbonate has been found to be particularly useful in the preparation of the flexible polyurethane foams of the present invention. The alkali metal Bronsted acid salts are generally used in amounts of from 0.01 to 1.5% by weight, preferably from 0.05 to 1.0% by weight, based on the isocyanate-reactive mixture (b).

It has surprisingly been found that the amine-based crosslinking agents of the formula II, in combination with the isocyanate-reactive mixtures (b) according to the invention, are effective in reducing the catalyst requirements, since these non-isocyanate-reactive catalysts have a low boiling point, e.g.1, 8-diazabicyclo- (5, 4, 0) -undecene-5, which has a boiling point of only 100 ℃ at a gas pressure of 532Pa, and which remain in the finished foam and are gradually released from the foam. Thus, the polyurethane foam prepared has a large amount of Volatile Organic Chemical (VOC) emission. The reduction in the amount of catalyst required can therefore lead to a substantial reduction in the Volatile Organic Compound (VOC) emissions of the flexible polyurethane foams of the present invention. The low VOC polyurethane foam conforms to the trend of environmental protection, and the use safety of the product is more perfect.

One or more surfactants may also be used in the foaming composition. Surfactants lower bulk surface tension, promote bubble nucleation, stabilize the frothed bubbles and emulsify incompatible ingredients. Suitable surfactants for use in preparing the polyurethane foams of the present invention are polysiloxane-polyalkyleneoxide copolymers, typically having an HLB value between 3 and 33, preferably in the present invention a polysiloxane-polyalkyleneoxide copolymer having an HLB value between 6 and 20. Other surfactants which may be used include non-silicon containing nonionic surfactants, cationic and anionic surfactants having an HLB value between 1 and 20, preferably between 6 and 20, and high molecular surfactants having a relative molecular weight above 1,000. The HLB value indicates the ratio between the lipophilicity and the hydrophilicity of a surfactant, the lower the HLB value, the more lipophilic the surfactant is, and conversely, the higher the HLB value, the more hydrophilic the surfactant used is. The preferred use of the polysiloxane-polyalkyleneoxide copolymer surfactant herein is generally used at a level of from 0.1 to 3 parts by weight, preferably from 0.5 to 2.5 parts by weight, based on 100 parts by weight of the total isocyanate-reactive mixture.

0.5 to 6.5 parts by weight (based on 100 parts by weight of the isocyanate-reactive mixture) of water are used to generate carbon dioxide by reaction with the isocyanate as a blowing agent for the blowing reaction. Flexible polyurethane foams having a density in the range from 8 to 160 kg/m can be obtained. With a higher water fraction, more carbon dioxide can be produced and thus a lower density flexible polyurethane foam can be obtained. In addition, if desired, combinations of water and other known auxiliary blowing agents, such as chlorofluorocarbons (HCFCs) or carbon dioxide, may be used. It is particularly preferred to use carbon dioxide (gas or liquid) directly as an auxiliary blowing agent other than water. It has also been found that adjusting the gas pressure and/or using mechanical frothing techniques during the foaming reaction, as described in WO 93/24304 issued 12 and 9, 1993 and U.S. Pat. No. 5,194,453 issued 3 and 16, 1993, can be used to vary the foam density.

Other additives may optionally be incorporated into the foaming compositions of the present invention. These other additives include, but are not limited to: pigments, antioxidants, UV light absorbers, UV light stabilizers, flame retardants, fillers, recycled foam powders, stabilizers, antimicrobial compounds, and antistatic agents. Such additives should not adversely affect the properties of the flexible polyurethane foam.

Although aliphatic and/or cycloaliphatic isocyanate-based polyurethane foams are not readily discolored by Ultraviolet (UV) radiation, aliphatic and/or cycloaliphatic isocyanate-based polyurethane foams may also be subject to photodegradation. To improve the light stability of the polyurethane foam, additives may be added to the polyurethane foam of the present invention. Additives are generally classified into three categories: hindered amine-based UV stabilizers, UV absorbers or antioxidants. By choosing the right mixing ratio of these additives, the UV stability of the polyurethane foam can be greatly improved, which results from the fact that the synergistic effect between these three types of stabilizers is manifested.

Antioxidants useful in the present invention can be of two broad classes, one being free radical chain blocking agents, such as hindered phenol series antioxidants, and the other being peroxide decomposers, such as thioesters and phosphites. The antioxidants are generally used in amounts of from 0.1 to 1.0% by weight, preferably from 0.3 to 0.6% by weight, based on the isocyanate-reactive mixture (b).

The UV absorbers which can be used in the present invention are mainly salicylates, benzotriazoles and benzophenones. Suitable salicylates are phenyl salicylate and tert-butylphenyl salicylate. Suitable benzotriazoles include 2- (2 '-hydroxy-3', 5 '-diisoamyl-phenyl) benzotriazole, 2- (2' -hydroxy-3 '-tert-butyl-5' -methylphenyl) -5-chlorobenzotriazole, 2- (2 '-hydroxy-3', 5 '-di-tert-butylphenyl) -5-chlorobenzotriazole, and 2- (2' -hydroxy-3 ', 5' -di-tert-butylphenyl) benzotriazole. As the benzophenone, 2 ' -dihydroxy-4, 4 ' -dimethoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2 ' -dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone and the like are suitable. The UV absorbers are generally added in amounts of from 0.1 to 3.0% by weight, preferably from 0.5 to 2.0% by weight, based on the isocyanate-reactive mixture (b).

Another class of additives useful in the present invention are hindered amine based UV stabilizers, preferred hindered amine UV stabilizers are bis (2, 2, 6, 6-tetramethylpiperidinyl) sebacate, poly [ [6- [ (1, 1, 3, 3-tetramethylbutyl) amino ] -s-triazine-2, 4-diyl ] - [ (2, 2, 6, 6-tetramethyl-4-piperidinyl) imino ] -hexamethylene- [ (2, 2, 6, 6-tetramethyl-4-piperidinyl) imino ] (chemical abstracts number 71878-19-8), bis (1, 2, 2, 6, 6-pentamethyl-4-piperidinyl) - [ [3, 5-bis (1, 1-dimethylethyl) -4-hydroxyphenyl ] methyl ] butyl malonate and 4-benzoyloxy-2, 2, 6, 6-tetramethylpiperidine. The hindered amine light stabilizer is generally added in an amount of 0.1 to 6.0% by weight, preferably 0.5 to 4.0% by weight, based on the isocyanate-reactive mixture (b).

The flexible polyurethane foams of the present invention can be prepared by molding and/or slabstock processes. The molding method is a method in which the reactive mixture is injected, foamed, and molded in a closed mold. The slab stock method refers to pouring the reactive mixture onto a conveyor belt and foaming in an open system.

The hardness of the flexible polyurethane foams of the present invention can be adjusted by selecting an appropriate isocyanate index or by selecting an appropriate isocyanate composition. Using higher isocyanate functional isocyanates in combination with an isocyanate index of greater than 120, the IFD 40% hardness of the flexible polyurethane foams of the present invention can be adjusted up to 200N/314cm². The isocyanate index is lower than 100 and the combination is lowerIsocyanate-functional isocyanates, the IFD 40% hardness of the flexible polyurethane foams of the present invention can be adjusted down to 30N/314cm². IFD 40% hardness was determined according to ASTM D3574-03.

The falling ball resilience of the flexible polyurethane foam of the present invention can be adjusted by adjusting the molecular weight of the polyoxyalkylene glycol in the isocyanate reactive component (b) and the isocyanate index used therewith. Using a polyoxyalkylene glycol having a molecular weight of more than 1,600 and an isocyanate index of not more than 115, a high resilience flexible polyurethane foam having a ball rebound of more than 60% can be obtained. Such a high resilience flexible polyurethane foam is suitably used for applications such as automobile seat cushions, furniture seat cushions, and bed mattresses because of its excellent elasticity.

Detailed Description

In the following detailed description, the symbols, terms and abbreviations used will have the following definitions:

ISO 1 is isophorone diisocyanate, a commercial product of Desmodur I from Bayer AG (Bayer).

ISO 2 is a mixture of 40 wt.% hexamethylene diisocyanate (Desmodur H) and 60 wt.% hexamethylene diisocyanate trimer (commercial Desmodur N3600), both produced by Bayer AG.

ISO 3 is hexamethylene diisocyanate, product Desmodur H from Bayer AG (Bayer).

ISO 4 is xylylene diisocyanate, a commercial product of Takenate 500 from Mitsui-Takeda Chemicals Inc. (Mitsui-Wuta chemical).

P1 is poly (tetramethylene ether) glycol having a hydroxyl equivalent weight of about 900, available from taiwan university chemical company.

P2 is a poly (trimethylene ether-ethylene ether) glycol prepared by the copolycondensation of 1, 3-propanediol and ethylene glycol, the ethylene ether content being about 20 parts by weight of the total poly (trimethylene ether-ethylene ether) glycol, the average hydroxyl equivalent weight being about 1,000, and the APHA color being about 30.

P3 is a poly (trimethylene ether) glycol prepared from bio-based 1, 3-propanediol having an average hydroxyl equivalent weight of about 1,070, an APHA color of about 25, produced by Cerenol from E.I.du Pont (DuPont)^TM H-2000。

P4 is a polyether polyol prepared by the addition polymerization of propylene oxide to a glycerol initiator using a potassium hydroxide catalyst followed by capping with ethylene oxide, and has an average molecular weight of 4,800g/mol, a hydroxyl number of about 27mg KOH/g, a primary hydroxyl functional group content of about 18% by weight of the total hydroxyl groups, and a nominal functionality of 3, available as ARCOLPOLYOL 34-28 from Bayer AG (Bayer).

DEOA is diethanolamine, more than 99% by weight pure, purchased from Sigma-Aldrich (Sigma Aldrich).

Glycerol was purchased from Sigma-Aldrich (Sigma Aldrich) in a purity of over 99% by weight.

DC5950 is a polysiloxane-polyalkyleneoxide copolymer surfactant, DABCODC 5950 available from air products and Chemicals Inc. (air chemical products, USA).

DC5526 is a polysiloxane copolymer surfactant, available from DABCO DC5526 of air chemicals ltd.

DC5179 is a low VOC emission polysiloxane-polyalkyleneoxide copolymer surfactant, available from DABCO DC5179 of air chemicals limited, usa.

DBU is 1, 8-diazabicyclo- (5, 4, 0) undecene-7, which is produced by Polycat DBU of air chemical products, Inc. of America.

DBU-Ph is phenolate of 1, 8-diazabicyclo- (5, 4, 0) undecene-7, produced by Polycat SA-1 of air chemical products, Inc., USA.

DBTDL refers to dibutyltin dilaurate, available from DABCO T-12 of air chemical products, Inc., USA.

SO refers to stannous octoate, produced by DABCOT-9 of air chemical products, Inc., USA.

MB is bismuth decanoate produced by DABCOMB-20 of air chemical products, Inc. of America, wherein decanoic acid is contained in an amount of not more than 20 parts by weight.

SBC was sodium bicarbonate, more than 99% pure, purchased from Sigma-Aldrich (Sigma Aldrich).

MPGC is 1- (4-methoxyphenyl) guanidine carbonate, chemical abstracts number 112677028, available from Sigma-Aldrich (Sigma Aldrich).

33LV was a dipropylene glycol solution prepared from 33% by weight of triethylenediamine, and was produced as DABCO 33LV by American air chemical Co.

BTA is 2- (2 ' -hydroxy-3 ', 5 ' -di-tert-amylphenyl) benzotriazole, chemical abstracts No. 25973-55-1, available from Taiwan Yongphotochemistry Inc.

PS is phenyl salicylate, chemical abstracts number 118-58-1, purity of over 99% by weight, purchased from Sigma-Aldrich (Sigma Aldrich).

AO is 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid n-octadecyl ester, chemical abstracts number 2082-79-3, Irganox 1076 from Ciba Geigy (Ciba-Geigy).

By "index" is meant the ratio of the total number of reactive isocyanate groups in the reaction mixture divided by the total number of isocyanate-reactive groups in the reaction mixture multiplied by 100.

"pbw" means parts by weight.

In the following detailed description, the properties of the polyurethane foams given in the examples are determined according to the following test methods:

"core density" is determined according to ASTM D3574-03.

"IFD (Indentation Force Deflection) hardness 40%" means determined according to ASTM D3574-03 using a 40% compressive load.

"tensile Strength" was determined according to ASTM D3574-03.

"elongation" is determined according to ASTM D3574-03.

"tear Strength" was determined according to ASTM D3574-03.

The "ball rebound resilience" of the core is determined according to ASTM D3574-03.

"gas flux" means the gas flux measured according to ASTM D3574-03, Test G method, expressed in cubic centimeters per minute. The test equipment was manufactured by Frazier (Md., USA).

The "UV stability" value is a measurement OF the colour fastness obtained according to AATCC (American society OF TEXTILE CHEMISTS and dyeing CHEMISTS, AMERICAN ASSOCIATION OF TEXTILE CHEMISTS ANDCOLORISTS) test standard 16-1990, option E method. The foam samples were placed under a UV lamp and exposed to UV light for 20 hours. The results are presented in a scale of 1-5 in comparison to a standard grayscale card. A rating of 5 means no color change at all and a rating of 1 means almost dark. Values of grade 4 and above indicate no visual change discernible to the naked eye.

The "wet swell" value is obtained by rolling a polyurethane foam sample having a length and width of 5cm and a thickness of 0.5cm twice with a stainless steel roller so that all cells are further completely opened. The samples were immersed in an aqueous solution of AATCC 1993 standard detergent WOB (without optical brightener and phosphate) maintained at 25 degrees celsius at a concentration of 0.5% by weight (based on 100% by weight of the total solution), and the container containing the samples and solution was placed in a 3 mm hg pressure vacuum chamber to allow the solution to fully penetrate the foam sample, and the container containing the samples and solution was then removed from the vacuum chamber. After 24 hours, the sheet was taken out, and the change in length and width was measured and expressed by the formula "wet swelling ratio ═ length after swelling-original length)/original length". The average of six values of the length and width of the three samples was taken and expressed as a percentage.

The "post-drying swell" value is obtained by rolling a polyurethane foam sample having a length and width of 5cm and a thickness of 0.5cm twice with a stainless steel roller so that all cells are further completely opened. The samples were immersed in an aqueous solution of AATCC 1993 standard detergent WOB (without optical brightener and phosphate) maintained at 25 degrees celsius at a concentration of 0.5% by weight (based on 100% by weight of the total solution), and the container containing the samples and solution was placed in a 3 mm hg pressure vacuum chamber to allow the solution to fully penetrate the foam sample, and the container containing the samples and solution was then removed from the vacuum chamber. After 24 hours, the sheet was taken out, washed with water, and naturally dried at room temperature for 120 hours, and then the change in length and width was measured, and expressed by the formula "swelling rate after drying ═ length after drying-original length)/original length". The average of six values of the length and width of the three samples was taken and expressed as a percentage.

The "accelerated washing and drying test" is a test in which a polyurethane foam sample having a length and width of 25 cm and a thickness of 5cm is immersed in an aqueous solution of the AATCC 1993 standard detergent WOB (containing no fluorescent whitening agent and phosphate) at a temperature of 50 c and a concentration of 0.5% by weight (based on 100% by weight of the total solution) for 16 hours, taken out, washed with water, and dried in an oven at 80 c for 8 hours. The soaking, water washing and drying processes are repeated for 20 times.

"tensile strength after washing with water" means that a foam sample subjected to the "accelerated washing and drying test" is cut into appropriate test pieces according to the method of ASTM D3574-03, and the tensile strength is measured according to the method of ASTM D3574-03.

"elongation after washing" means that a foam sample after being subjected to the "accelerated washing and drying test" is cut into appropriate test pieces according to the method of ASTM D3574-03, and the elongation is measured according to the method of ASTM D3574-03.

"tear Strength after washing with water" means that a foam sample subjected to the "accelerated washing and drying test" was cut into appropriate test pieces according to ASTM D3574-03, and the tear strength was measured according to ASTM D3574-03.

The "moldability" is a molding evaluation, and a foam having a good surface layer after foaming and no shrinkage is evaluated as "good", a foam having shrinkage after foaming but recovered after two successive passes with a roll mill is evaluated as "rollable", and a foam having shrinkage and no recovery after two passes with rolling is evaluated as "poor".

The following examples are intended to illustrate the invention and should not be construed as in any way limiting its scope. All parts and percentages are parts by weight and percentages by weight, unless otherwise indicated.

Examples 1-25 and comparative examples C1-C5

Examples 1 to 7 and comparative examples C1 to C5

Flexible polyurethane foams of examples 1-7 and comparative examples C1-C5 were prepared by mixing the components shown in Table 1. All selected ingredients were conditioned for at least 24 hours in an incubator controlled at a temperature of 26 ± 1 ℃ prior to preparation. The ingredients other than the organotin compound and isocyanate were premixed and brought together within 40 seconds using a Cowles type mixer set at a rotational speed of 1,500rpm in a 1.5 liter stainless steel cup prior to the addition of the organotin compound. After premixing, the organotin compound was then charged into the cup and mixed for another 20 seconds with the rotational speed set at 1,500 rpm. The selected isocyanate compound was then added to the resulting mixture and mixed with the resulting composition at 3,000rpm for 5 seconds. The mixture was then poured into a paper lined wood box with the top open at 45 cm (length) 45 cm (width) 45 cm (height) and foamed. After the foam reached its final height, it was allowed to rest in the box for an additional 10 minutes and then removed from the box. The foam obtained is then stored in a ventilated storage chamber at a temperature of 27. + -. 2 ℃ for at least 72 hours.

Foam samples were then cut from the foam cores produced using a laboratory scale electric saw according to the sample dimensions described in ASTM D3574-03 method. Samples for testing swell, tear strength, tensile strength and elongation were then die cut from foam boards of the specified thickness according to the sample dimensions described in astm d3574-03 methods. All samples were conditioned for at least 24 hours in a room with temperature controlled at 23 ± 1 ℃ and humidity of 50% prior to physical property testing.

TABLE 1

^(*): results from crushing broken foam samples.

Closed cell foams were obtained in example 5 and comparative examples C3 and C4, and the foams began to shrink as the internal temperature began to drop. The foam cells were broken by rolling the foam twice through a pair of motorized stainless steel roller breakers to prevent further shrinkage. The rolled broken foam was conditioned in a room temperature controlled at 23 ± 1 ℃ for at least 72 hours prior to further physical property testing. The physical properties illustrated in example 5 and comparative examples C3 and C4 were determined using samples cut from the foam core after rolling to break the foam.

Examples 1-7 illustrate the processability, foam mechanical properties and formulation flexibility in the preparation of flexible polyurethane foams of the present invention.

Examples 8 to 19

Table 2 examples 8-19 were prepared using the same procedure used in the preparation of examples 1-7, all selected ingredients being temperature conditioned for at least 24 hours in an incubator controlled to a temperature of 26 ± 1 ℃ prior to preparation.

Foam samples were then cut from the foam cores produced using a laboratory scale electric saw according to the sample dimensions described in ASTM D3574-03 method. Samples for testing were then die cut from foam boards of the specified thickness according to the sample dimensions described in astm d3574-03 method. All samples were conditioned for at least 24 hours in a room with temperature controlled at 23 ± 1 ℃ and humidity of 50% prior to further physical property testing.

The foam physical property tests of examples 8-19 were carried out according to the same procedures as shown in examples 1-7, except for the UV stability test. In the UV stability test, a sample of 5cm (width) 10cm (length) 0.5cm (thickness) was placed in an oven with an internal temperature set at 80 ± 1 ℃, and an OSRAM ULTRA-vitaux 300 watt UV bulb was mounted 30cm directly above the foam sample. The samples were exposed to uv light for 20 hours. The results are presented in a scale of 1-5 in comparison to a standard grayscale card. A rating of 5 means no color change at all and a rating of 1 means almost dark. Values of grade 4 and above indicate no visual change discernible to the naked eye.

Closed cell foams were obtained in examples 10 and 16, and the foams began to shrink as the internal temperature began to drop. The foam cells were broken by rolling the foam twice through a pair of motorized stainless steel roller breakers to prevent further shrinkage. The rolled broken foam was conditioned in a room controlled at 23 ± 1 ℃ for at least 72 hours before further physical property testing. The physical properties illustrated in examples 10 and 16 were determined using samples cut from foam cores after breaking the foam by rolling.

Examples 20 to 21

Table 3 examples 20-21 were prepared using the same procedure used in the preparation of examples 1-7, and immediately after mixing, the mixture was poured into an aluminum mold having an internal dimension of 40 cm (length) 40 cm (width) 10cm (height) and preheated to 60 ℃, with 4 holes left in the top of the mold cover, and the mold was maintained at 60 ℃ and covered. After keeping the mold temperature at 60 ℃ for 10 minutes, the flexible polyurethane foam was taken out of the mold. The foam obtained is then stored in a ventilated storage chamber at a temperature of 27. + -. 2 ℃ for at least 72 hours.

Foam samples were then cut from the foam cores produced using a laboratory scale electric saw according to the sample dimensions described in ASTM D3574-03 method. Samples for testing were then die cut from foam boards of the specified thickness according to the sample dimensions described in astm d3574-03 method. All samples were conditioned for at least 24 hours in a cabinet controlled at 23 ± 1 ℃ and 50% humidity prior to physical property testing.

TABLE 3

^(*): results from foam samples after rolling out the broken foam.

In example 21, a closed cell foam was obtained, which started to shrink as the internal temperature started to drop. The cells were crushed twice by passing the foam through a pair of motorized stainless steel roller breakers to prevent further shrinkage. The crushed foam was conditioned in a room temperature controlled at 23 ± 1 ℃ for at least 72 hours before further physical property testing. The physical properties illustrated in example 21 were determined using samples cut from the foam core after crushing to break the foam.

Examples 22 to 25

The same procedures used in the preparation of examples 1-7 were used to prepare examples 22-25 of Table 4. After mixing was complete, the mixture was poured into a 45 cm (length) 45 cm (width) 45 cm (height) paper lined wood box with the top open, which was then moved into a pressure tank (Autoclave) and the pressure inside the pressure tank was rapidly adjusted to the pressure indicated in Table 4 before the volume of the mixture started to foam and expand. During the expansion of the foam, the air pressure inside the pressure cell is controlled to be maintained at this pressure level. After the foam reached its final height, it was allowed to rest in the box for an additional 15 minutes, and then the pressure cell was opened and the foam removed from the box. The foam obtained is then stored in a ventilated storage chamber at a temperature of 27. + -. 2 ℃ for at least 72 hours.

Foam samples were cut from the foam cores produced using a laboratory scale electric saw according to the sample dimensions described in ASTM D3574-03 method. Samples for testing were then die cut from foam boards of the indicated thickness according to the sample dimensions described in the ASTM D3574-03 method. All samples were conditioned for at least 24 hours in a cabinet controlled at 23 ± 1 ℃ and 50% humidity prior to physical property testing.

TABLE 4

^(*): results from foam samples after rolling out the broken foam.

INDUSTRIAL APPLICABILITY

The flexible polyurethane foam of the present invention has excellent weather resistance and water washing deformation resistance, and is especially suitable for clothing. Does not emit any aromatic amine after washing for a long time in a hot and humid environment, and is suitable for use as a filling material for underwear pads, shoulder pads, and also for use in bed pads, pillows, furniture pads, and automobile seat pads. It is particularly suitable for underwear and shoulder pads.

Claims (22)

1. A flexible polyurethane foam comprising the reaction product of:

a. an isocyanate component that is substantially free or free of aromatic isocyanates having isocyanate groups directly attached to aromatic rings;

b. an isocyanate reactive mixture comprising at least one polyoxyalkylene diol;

c. one or more blowing agents;

d. at least one catalyst; and

e. optionally one or more selected from the group consisting of: surfactants, cross-linking agents and additives;

wherein the foam has a density in the range of from 8 to 160 kilograms per cubic meter, a gas flow rate of greater than 5,000 cubic centimeters per minute as measured according to ASTM D3574-03, a ball rebound of greater than 20 percent, and is prepared at an isocyanate index of from 80 to 135, preferably from about 85 to 130, more preferably from about 90 to 125.

2. The foam of claim 1 wherein the isocyanate component is selected from one or more of the following isocyanates: aliphatic isocyanates, cycloaliphatic isocyanates and aromatic isocyanates in which the isocyanate groups are not directly attached to an aromatic ring.

3. The foam of claim 1 or 2, wherein the aliphatic isocyanate comprises a blend of an aliphatic polyisocyanate monomer or an aliphatic polyisocyanate monomer and a trimer, the trimer being the product of the trimerization of an aromatic polyisocyanate in which the aliphatic or cycloaliphatic or isocyanate groups are not directly attached to the aromatic ring, the blend having an NCO functional group content of from 20.5 to 50.0 parts by weight, based on 100 parts by weight of total isocyanate in the isocyanate component, and an average calculated functionality of from 2 to 3, preferably the aliphatic polyisocyanate is hexamethylene diisocyanate, and the trimer is the product of the trimerization of hexamethylene diisocyanate.

4. A foam according to any one of claims 1 to 3 wherein the cycloaliphatic isocyanate comprises a cycloaliphatic polyisocyanate monomer or a blend of cycloaliphatic polyisocyanate monomers and trimers which are the product of the trimerisation of aromatic polyisocyanates having aliphatic or cycloaliphatic or isocyanate groups which are not directly attached to aromatic rings, the blend having an NCO functional group content of from 20.5 to 38.0 parts by weight, based on 100 parts by weight of total isocyanate in the isocyanate component, and an average calculated functionality of from 2 to 3, preferably the cycloaliphatic polyisocyanate is isophorone diisocyanate and the trimers are the product of the trimerisation of hexamethylene diisocyanate.

5. The foam according to any one of claims 1 to 4, wherein the aromatic isocyanate in which the isocyanate groups are not directly bonded to the aromatic ring comprises a blend of an aromatic polyisocyanate monomer in which the isocyanate groups are not directly bonded to the aromatic ring or an aromatic polyisocyanate monomer in which the isocyanate groups are not directly bonded to the aromatic ring and a trimer which is the product of the trimerization reaction of an aliphatic or alicyclic aromatic polyisocyanate in which the isocyanate groups are not directly bonded to the aromatic ring, said blend having an NCO functional group content of 20.5 to 44.0 parts by weight based on 100 parts by weight of total isocyanate in the isocyanate component and an average calculated functionality of 2 to 3, preferably the aromatic polyisocyanate in which the isocyanate groups are not directly bonded to the aromatic ring is xylylene diisocyanate or tetramethylxylylene diisocyanate, the trimer is a product of a trimerization reaction of hexamethylene diisocyanate.

6. The foam of any of claims 1-5, wherein the aliphatic isocyanate comprises at least one selected from the group consisting of: hexamethylene diisocyanate, hexamethylene triisocyanate, undecane diisocyanate, dodecane diisocyanate, dimers and trimers thereof.

7. The foam of any of claims 1-6, wherein the cycloaliphatic isocyanate comprises at least one selected from the group consisting of: bicycloheptane triisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, dimethylcyclohexane diisocyanate, dimers and trimers thereof.

8. The foam of any of claims 1-7, wherein the aromatic isocyanate in which the isocyanate groups are not directly attached to an aromatic ring is at least one selected from the group consisting of: xylylene diisocyanate, tetramethylxylylene diisocyanate, dimers and trimers thereof.

9. The foam of any of claims 1-8 wherein the isocyanate reactive component (b) is a polyoxyalkylene glycol compound of formula I

H-[O-(CH₂)_m-]_nOH (formula I)

Wherein the number m of methylene groups in each unit is independently 2, 3 or 4, or 3 or 4, and the number n of units is an integer of 14 to 90.

10. The foam of any of claims 1-9 wherein the isocyanate reactive component (b) is a poly (trimethylene ether-ethylene ether) glycol compound obtained by the polycondensation of 1, 3-propanediol and ethylene glycol; preferably, the ethylene ether segment content is less than 30 parts by weight, preferably from 5 to 30 parts by weight, more preferably from 5 to 20 parts by weight, based on 100 parts by weight of the poly (trimethylene ether-ethylene ether) glycol compound; and/or the weight average molecular weight of the poly (trimethylene ether-ethylene ether) glycol compound is 600-4,000 g/mol, preferably 1,000-5,000 g/mol.

11. The foam according to any of claims 1 to 10, wherein the isocyanate reactive component (b) is a polyoxyalkylene glycol compound and/or a poly (trimethylene ether-ethylene ether) glycol compound prepared from 1, 3-propanediol or 1, 4-butanediol, preferably one or more of poly (trimethylene ether) glycol, poly (tetramethylene ether) glycol and poly (trimethylene ether-ethylene ether) glycol, more preferably a polyoxyalkylene glycol compound and/or a poly (trimethylene ether-ethylene ether) glycol compound derived from 1, 3-propanediol or 1, 4-butanediol prepared from fermentation of renewable vegetable raw materials.

12. The foam of any of claims 1-11, wherein the blowing agent (c) is selected from at least one of the following: water, chlorofluorocarbons (HCFCs) and carbon dioxide.

13. The foam of any one of claims 1-12, wherein the catalyst (d) is at least one selected from the group consisting of: (1) salts of bronsted acids with alkali metals or alkaline earth metals, (2) compounds containing > N-C ═ N-linkages in the molecular structure, (3) organic salts of compounds containing > N-C ═ N-linkages in the molecular structure, and (4) organometallic catalysts.

14. The foam of claim 13 wherein the salt of the bronsted acid with an alkali metal or alkaline earth metal is sodium carbonate or sodium bicarbonate.

15. The foam of claim 13, wherein the compound (2) having a molecular structure with > N-C ═ N-linkages is at least one selected from the group consisting of: diazabicyclo olefins or guanidines and derivatives thereof; the organic salt of a compound having > N-C ═ N-linkage in the molecular structure (3) is at least one selected from the group consisting of: organic salts of diazabicyclo olefins or guanidines and derivatives thereof.

16. The foam of claim 15, wherein the compound having > N-C ═ N-linkage in the molecular structure (2) is 1, 8-diazabicyclo- (5, 4, 0) -undecene-5, and the organic salt having > N-C ═ N-linkage in the molecular structure (3) is phenolate salt of 1, 8-diazabicyclo- (5, 4, 0) -undecene-5.

17. The foam of claim 13, said organometallic catalyst (4) being at least one selected from the group consisting of: organotin compounds, organotin stannous compounds and organobismuth compounds.

18. The foam of any one of claims 1 to 17, wherein the surfactant is a nonionic surfactant having an HLB value of 6 to 20.

19. The foam of any of claims 1-18, wherein the cross-linker has a weight average molecular weight of 60 to 420g/mol and has at least two isocyanate reactive functional groups; and/or the crosslinking agent is used in an amount of 0.2 to 15 parts by weight, most preferably 1.2 to 12 parts by weight, based on 100 parts by weight of the isocyanate-reactive mixture.

20. The foam of any of claims 1-19, wherein the cross-linking agent is of formula II

H_(3-x)-N-[(CH₂)₂-OH]_x(formula II)

Wherein x represents an integer from 1 to 3.

21. The foam of any of claims 1-20, wherein the crosslinker is diethanolamine.

22. A process for the preparation of a foam according to any of claims 1 to 21, comprising reacting components a to e as defined in any of claims 1 to 21 at an isocyanate index of from 80 to 135, preferably from about 85 to 130, more preferably from about 90 to 125.