JPH0959335A - Production of polyurethane foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively produce a polyurethane foam having high air permeability by using a dispersion obtained by stably dispersing fine particles of a metal oxide into a polyol. SOLUTION: In this method for producing a polyurethane foam by reacting a polyol with an organic polyisocyanate in the presence of a catalyst using water as a foaming agent, 0.01-15wt.% fine particles of a metal oxide having <=10000nm particle diameter are added and dispersed into the polyol and a surfactant comprising a partially esterified material of a polyhydric alcohol with a fatty acid is used as a dispersant of the fine particles to the polyol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stably dispersing fine particles of a metal oxide in a polyol, and using the polyol component to produce a polyurethane foam having high interconnectivity.

[0002]

2. Description of the Related Art Heretofore, as a method for producing a polyurethane foam having high interconnectivity by using an additive, a method of dispersing fine particles of a metal oxide in a polyol (JP-A-54-1).
54498), a method of dispersing metal oxide fine particles or sol in a polyol (JP-A-5-239169), and a method of dispersing alumina sol in a polyol (JP-A-5-59).
143) and the like are known.

[0003]

However, in the method of dispersing fine particles of a metal oxide in the above-mentioned polyol, the fine particles of a metal oxide are not uniformly dispersed but are separated and settled, which makes it difficult to re-disperse them on the bottom of the storage container. There was a problem that cakes were produced. On the other hand, the method of dispersing the metal oxide sol in the polyol has solved the problem of separation and sedimentation, but has the problem that the metal oxide sol is more expensive than the metal oxide fine particles.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made extensive studies as to a method for producing a polyurethane foam which solves these problems, and as a result, use fine particles of a metal oxide as an additive for a polyol and By using a surfactant selected from the partial esters of polyhydric alcohols as a dispersant for the fine particles of the product in the polyol, separation and settling of the fine particles of the metal oxide is prevented, and the polyol component is used to maintain the compatibility. It has been found that a polyurethane foam having a high cost can be produced, and the present invention has been completed.

That is, according to the present invention, a polyurethane foam is obtained by reacting a polyol (a) and an organic polyisocyanate (b) with water as a foaming agent in the presence of a foam stabilizer (c) and a catalyst (d). In the manufacturing method, in (a),
0.01 to 15% by weight of metal oxide fine particles (e) having an average particle diameter of 10,000 nm or less based on the weight of (a).
A polyurethane characterized in that it is added and dispersed, and a surfactant (f) comprising a partial esterification product of a polyhydric alcohol and a fatty acid having 10 or more carbon atoms is used as a dispersant for (a) in (e). It is a method of manufacturing a foam.

As the polyol (a) used in the present invention, those usually used for polyurethane are used.
Examples thereof include polyether polyols, polyester polyols, castor oil, and polymer polyols obtained by polymerizing vinyl monomers in these polyols.

Examples of the polyether polyol include alcohols, amines, and alkylene oxide adducts such as ammonia. Examples of alcohols include monohydric alcohols (methanol, ethanol, butanol, etc.); dihydric alcohols (ethylene glycol, propylene glycol, 1,6-hexanediol, etc.); trihydric alcohols (glycerin, trimethylolpropane). Etc.); tetrahydric alcohols (pentaerythritol, methyl glucoside, etc.); octahydric alcohols (sucrose, etc.) and the like. As amines, monovalent amines (dimethylamine, diethylamine, etc.); divalent amines (methylamine, ethylamine, aniline, etc.); 3
Examples include valent amines (monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, etc.); tetravalent amines (ethylenediamine, hexamethylenediamine, etc.). As the alkylene oxide, ethylene oxide, propylene oxide,
1,2-, 1,4- and 2,3-butylene oxide and a combination of two or more of these.

Polyester polyols are obtained by reacting low molecular weight polyols [the above-mentioned dihydric alcohols, trimethylolpropane, glycerin, etc.] with polycarboxylic acids [succinic acid, adipic acid, phthalic acid, terephthalic acid, etc.]. Examples include condensed polyester polyols, polyester polyols obtained by ring-opening polymerization of lactones [ε-caprolactam, etc.], and recovered polyester polyols obtained by decomposing polyester resin molded products.

Examples of the polymer polyol include those obtained by polymerizing and stably dispersing vinyl monomers such as acrylonitrile and styrene in at least one of the above-exemplified polyols in the presence of a radical initiator. The content of the vinyl polymer in the polymer polyol is usually 10-50.
% By weight.

Among the examples exemplified as (a) above, preferred are polyether polyols, polyester polyols, polymer polyols and combinations of two or more of these.

As the organic polyisocyanate (b),
Known polyurethanes usually used in polyurethane, for example, aromatic polyisocyanate having 6 to 20 carbon atoms (excluding the carbon number in the NCO group) [2,4- or 2,6-tolylene diisocyanate (TDI), crude TDI , 2,4'- or 4,4'-diphenylmethane diisocyanate (MDI), crude MDI, etc.]; Aliphatic isocyanate having 2 to 18 carbon atoms (hexamethylene diisocyanate, lysine diisocyanate, etc.); Alicyclic ring having 4 to 15 carbon atoms Formula polyisocyanates (isophorone diisocyanate, dicyclohexyl diisocyanate, etc.); modified products of these polyisocyanates (containing urethane group, carbodiimide group, allophanate group, urea group, uretdione group, buret group, uretonimine group, isocyanurate group, oxazolidone group) Gender, etc.); and combinations of two or more of these.

Preferred among these (b) are TDI, MDI, crude MDI and a combination of two or more thereof.

As the foam stabilizer (c), those usually used in polyurethane are used, and specific examples thereof include dimethylsiloxane-based foam stabilizers such as "L-5309" and "SZ-" manufactured by Nippon Unicar Co., Ltd. 1306 "," L-52
0 "and" L-540 "; Torre Dow Corning
"SH-190", "SH-19" manufactured by Silicone Co., Ltd.
3 ”and“ SRX-274C ”.

As the catalyst (d), known ones usually used in polyurethane, for example, metal salts of carboxylic acids (sodium acetate, lead octylate, zinc octylate, cobalt naphthenate, stannas octoate, etc.); alkali Metal or alkaline earth metal alkoxides or phenoxides (sodium methoxide, sodium phenoxide, etc.); tertiary amines (triethylamine, triethylenediamine, N-methylmorpholine, dimethylaminomethylphenol, pyridine, etc.); quaternary ammonium salt (tetraethyl Hydroxylammonium, etc.); imidazoles (imidazole, 2-ethyl-4-methylimidazole, etc.); and organometallic compounds containing metals such as tin and antimony (tetraphenyltin, tributylantimono). Side, etc.) and the like. Of these, preferred are metal salts or organic metal compounds of carboxylic acids containing tertiary amines and tin or antimony.

Examples of the fine particles (e) of the metal oxide added and dispersed in (a) include fine particles of aluminum oxide, silicon oxide, zinc oxide, antimony oxide, etc. Among these, preferable ones are aluminum oxide. , Silicon oxide, and particularly preferred is aluminum oxide.
The particle size of (e) is usually 10000 nm or less, preferably 1
It is 000 nm or less. When the particle size exceeds 10,000 nm, the dispersion stability in the polyol (a) becomes poor.

Polyurethane foam obtained by foaming (a) in which (e) is stably dispersed is used as a polyol component has high continuity. Therefore, flexible polyurethane foam has a small molding shrinkage ratio, a high rebound resilience, and a compression residue. The strain rate and the residual strain rate under wet heat are small, while the rigid polyurethane foam has an excellent dimensional stability.

The surfactant (f) used as a dispersant for (e) to (a) is a partial esterified product of a polyhydric alcohol (sorbit, sorbitan, sucrose, etc.) and a fatty acid having 10 or more carbon atoms. Among these, preferred ones are partial esterified products of sorbitan and fatty acids having 10 or more carbon atoms, and particularly preferred ones are partially esterified products consisting of 1 mol of sorbitan and 1 mol of fatty acids having 16 to 20 carbon atoms. Is.

In the present invention, when the surfactant (f) is not used, the (e) is not uniformly dispersed in the polyol but is separated and settled, and a hard cake is produced at the bottom of the storage container. This hard cake is difficult to redisperse even if the polyol component is stirred.

On the other hand, when (f) is used, (e) can be uniformly dispersed in the polyol and separation and sedimentation can be prevented. Further, in this case, even if (e) is separated and settled, it is the soft cake that is generated at the bottom of the storage container, and this soft cake can be easily redispersed by stirring the polyol component. Further, since (f) has a hydroxyl group, it does not react with (b) in the urethane foaming reaction stage and does not bleed out from the foam over time.

In the method of the present invention, a chain extender and / or a crosslinking agent (g) can be optionally used. What is usually used for polyurethane is used as the (g), and specific examples include ethylene glycol,
Examples include diethanolamine, triethanolamine, glycerin, triomethylolpropane, pentaerythritol, D-sorbit, and the like, to which propylene oxide and / or ethylene oxide are added so that the active hydrogen equivalent is 150 or less. Is also included.

Water in the production method of the present invention, (b),
The amounts of the components (c), (d), (e) and (f) used are as follows. The amount of water is usually 1 to 8 parts by weight per 100 parts by weight of (a), and the density of the polyurethane foam can be adjusted by the amount of water used. However, if the amount is less than 1 part by weight, the amount of heat generated is small, so that the curing time becomes long and the productivity is lowered, and if it exceeds 8 parts by weight, foaming becomes unstable, which is not suitable for practical use. Regarding the amount of (b), the NCO index [equivalent of isocyanate group of (b) to 100 equivalent of active hydrogen of polyol component × 100] is usually 70 to 500, preferably 90 to.
The amount is 300. When the NCO index is less than 70, the curing time becomes long and the productivity is lowered, and the hardness of the foam becomes small, and when it exceeds 500, the foamed polyurethane foam becomes brittle and is not suitable for practical use. The amount of (c) is
(A) It is usually 0.1 to 5 parts by weight, preferably 0.3 to 2.0 parts by weight, per 100 parts by weight. The amount of (d) is
(A) It is usually 0.1 to 5 parts by weight per 100 parts by weight.
The amount of (e) is usually 0.01 to 100 parts by weight of (a).
It is 15 parts by weight, preferably 0.1 to 10 parts by weight.
If (e) is less than 0.01 parts by weight, the effect of improving air permeability cannot be obtained, and if it exceeds 15 parts by weight, the cells become unstable during foaming of the polyurethane foam, which is not suitable for practical use. (F)
Is usually 2 to 100% by weight based on the amount of (e). If it is less than 2% by weight, the effect of stable dispersion of (e) is small, and if it exceeds 100% by weight, the physical properties of the foam may be adversely affected such that the hardness of the obtained polyurethane foam is lowered.

A mixture of predetermined amounts of the components (a), (c), (d), water, (e) and (f) and (b) are stirred and mixed by a conventional method to foam. By
A polyurethane foam is obtained.

The polyurethane foam molding method using the method of the present invention includes a slab foaming method and a mold foaming method.

[0024]

Hereinafter, the present invention will be further described by way of examples, but the present invention is not limited thereto. In addition, the numerical value of the foaming prescription column in an Example and a comparative example shows a weight part.

[0025]

【Example】

Example 1 and Comparative Example 1 According to the foaming recipe shown in Table 1, a flexible polyurethane foam was molded and foamed in a mold, and taken out from the mold.
After standing overnight, the polyurethane foam was cut and its physical properties were measured. Table 1 shows the results.

[0026]

[Table 1]

Example 2 and Comparative Example 2 In accordance with the foaming formulation shown in Table 2, a rigid polyurethane foam was slab-foamed in a box, taken out of the box, left standing for a whole day and night, and then the polyurethane foam was cut to measure its physical properties. . The results are shown in Table 2.

[0028]

[Table 2]

Examples 3 to 6 and Comparative Examples 3 to 5 According to the formulation shown in Table 3, (e) was dispersed in (a) and its dispersion stability (appearance judgment; immediately after dispersion, 20 days later) and dispersibility ( (Comparison between Example 6 and Comparative Example 5) was measured.
The results are shown in Table 3 and Table 4, respectively. The dispersibility was measured by a laser diffraction / scattering type particle size distribution measuring apparatus "LA-700" manufactured by Horiba Ltd. in the particle size distribution graph.

[0030]

[Table 3]

The evaluation criteria of dispersion stability in Table 3 are as follows. White uniform dispersion; Upper layer; White uniform dispersion, lower layer; Soft cake (can be easily and uniformly re-dispersed by stirring); White non-uniform dispersion (a large number of coarse particles are visually recognized); Upper layer; White uniform dispersion, lower layer; Hard Cake (difficult to uniformly disperse even with stirring); upper layer; transparent, intermediate layer; white uniform dispersion, lower layer; hard cake (difficult to uniformly disperse with stirring)

[0032]

[Table 4]

As is clear from Table 4, there is a significant difference in the initial dispersibility depending on whether or not the dispersion stabilizer is used.

(Explanation of Symbols of Starting Materials) Polyether polyol (a) a-1: Propylene oxide-ethylene oxide adduct of glycerin, active hydrogen equivalent = 1600, ethylene oxide terminal content 16% by weight a-2: a- 1, a polymer polyol obtained by copolymerizing acrylonitrile and styrene in 1, acrylonitrile content 20% by weight, styrene content 20% by weight a-3: sucrose propylene oxide adduct, active hydrogen equivalent = 134 a-4 : Propylene oxide adduct of glycerin, active hydrogen equivalent = 1000 Organic polyisocyanate (b) b-1: (TDI / crude MDI = 80/20 mixture, N
CO% = 44.7) b-2: MR-200 manufactured by Nippon Polyurethane Industry Co., Ltd.
(NCO% = 31) Foam stabilizer (c) c-1: L-5309 manufactured by Nippon Unicar Co., Ltd. c-2: SH manufactured by Toray Dow Corning Silicone Co., Ltd.
-193 Catalyst (d) d-1: Minicoal L-1020 manufactured by Activator Chemical Co., Ltd.
(33% dipropylene glycol solution of triethylenediamine) d-2: TOYOCAT ET (bis-
70% dipropylene glycol solution of N, N-dimethylaminoethyl ether) Metal oxide fine particles (e) e-1: aluminum oxide, particle size 400 to 2000 nm Surfactant (f) f-1: Sanyo Chemical Industries ( Ionet S-80
(Sorbitan monooleate) Chain extender, cross-linking agent (g) g-1: Diethanolamine and other auxiliaries (h) h-1: trischloropropylphosphate (mold foaming conditions) Mold shape: 400 mm x 400 mm x 100 mm Material: Aluminum Mold temperature: 62 ± 2 ° C Foaming method: (a), water, (c), (d), (e),
After plexing each component of (f), add (b) and add 6
It was stirred for 2 seconds and poured into the mold. Mixing method: Hand mixing Rotation speed of stirring blade: 5000 rotations / minute Raw material temperature: 25 ± 1 ° C. (Slab foaming condition) Mold shape: 300 mm × 300 mm × 250 mm Material: Aluminum Foaming method: (a), water, (c) ), (D), (e),
After premixing each component of (f), (b) was added, and the mixture was stirred for 6 seconds and poured into a mold. Mixing method: Hand mixing Stirring blade rotation speed: 5000 rotations / min Raw material temperature: 25 ± 1 ° C

(Explanation of Symbols in Physical Properties Column in Tables 1 to 3) A: Shows the apparent density of the flexible polyurethane foam. The unit is kg / m ³ . B: Indicates the hardness of flexible polyurethane foam. Unit is k
gf. C: Rebound resilience of flexible polyurethane foam. Units%. D: Shows the compression residual strain rate of the flexible polyurethane foam. Units%. E: Shows the wet heat residual strain rate of the flexible polyurethane foam. Units%. (Measurement of the physical properties of the foam of the above a to e is JIS K 64
Compliant with 01. However, the measurement of wet heat residual strain rate is 50 ° C under the condition of 70 ° C for 22 hours at the time of measuring compressive residual strain rate,
95% R.I. H. It was measured for 22 hours. ) F: Indicates the air permeability of flexible polyurethane foam. The unit is ft ³ / min. . (The above-mentioned physical properties of the foam were measured with a Dow type air flow meter MODEL DA.) G: Shows the molding shrinkage of the flexible polyurethane foam. Units%. (Measurement method of the above-mentioned G: After crushing the urethane foam immediately after demolding, the thickness Amm of the central part of the molded product was measured and calculated by the following equation: Molding shrinkage ratio = (100−A) / 100 × 100) The density of a rigid polyurethane foam is shown. Unit is k
g / m ³ . Re: Indicates the compressive strength of rigid polyurethane foam. The unit is kgf / cm ² . (Measurement of physical properties of foams described above is conducted according to JIS A 95
14 was complied with. ) Nu: Indicates the closed cell rate of the rigid polyurethane foam. Units%. (Measurement of the physical properties of the foam in the above is according to ASTM D-285.
According to 6-70. ) Le: shows the dimensional stability of rigid polyurethane foam. (Measurement method of the above item: represents the presence or absence of deformation of the foam sample left at 25 ° C. for 30 days after foaming.
Deformation is indicated by x. )

[0036]

By using the method of the present invention, it becomes possible to stably disperse fine particles of a metal oxide in a polyol. Polyurethane foam foamed using a polyol in which fine particles of metal oxides are stably dispersed has high continuity, so flexible polyurethane foam has a low molding shrinkage ratio, high impact resilience, compressive residual strain rate and wet heat residual strain. The effect is that the ratio is small, while the rigid polyurethane foam has the effect that the dimensional stability is good.

Claims (3)

[Claims] 1. A method for producing a polyurethane foam by reacting a polyol (a) and an organic polyisocyanate (b) with water as a foaming agent in the presence of a foam stabilizer (c) and a catalyst (d). In (a), the average particle size is 1000
0.01 to 15% by weight of fine particles (e) of a metal oxide having a size of 0 nm or less are added and dispersed with respect to the weight of (a), and a polyhydric alcohol is used as a dispersant for (a) of (e). A method for producing a polyurethane foam, which comprises using a surfactant (f) comprising a partial esterified product of a fatty acid having 10 or more carbon atoms. 2. The production method according to claim 1, wherein (e) is fine particles of aluminum oxide. 3. (f) is 1 mol of sorbitan and 16 carbon atoms
The method according to claim 1 or 2, wherein the surfactant is a partial esterified product of 1 to 18 mol of fatty acid.