JPH03128913A - Production of highly resilient polyurethane foam - Google Patents

Abstract

PURPOSE:To produce a highly resilient polyurethane foam having a low density by reacting a polyol with a polyisocyanate contg. diphenylmethane diisocyanate (deriv.) in the presence of a specific catalyst, a blowing agent contg. water, and a foam stabilizer. CONSTITUTION:In a process for producing a polyurethane foam by reacting a polyol with a polyisocyanate in the presence of a catalyst, a blowing agent, and a foam stabilizer, the following components are used: a polyisocyanate at least contg. diphenylmethane diisocyanate and/or a mixture thereof with a deriv. thereof; a blowing agent contg. water and a halogenated hydrocarbon (e.g. trichloromonofluoromethane) in an amt. of the blowing agent of 2 pts.wt. or higher and in an amt. of the halogenated hydrocarbon of 20 pts.wt. or lower (both based on 100 pts.wt. polyol); and a catalyst comprising an imidazole compd. of the formula (wherein R<1> is 1-4C alkyl, benzyl, vinyl, etc.; R<2> is H, 1-4C alkyl, allyl, phenyl, etc.; and R<3> and R<4> are each H, 1-4C alkyl, or hydroxymethyl). Thus, a decrease in the density of a high-resilience foam is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is directed to the use of polyols and polyisocyanates as catalysts,
This invention relates to a method for producing highly elastic polyurethane foam by reacting it in the presence of a blowing agent and a foam stabilizer.

More specifically, the present invention relates to a method for producing a highly elastic flexible polyurethane foam using a polyether polyol or a mixture of a polyether polyol and a polymer polyol, and diphenylmethane diisocyanate-1 and/or its derivatives.

[Prior Art] Highly elastic polyurethane foam is widely used in many products such as automobile seat cushions, vehicles, furniture, and bedding.

Conventionally, toluene diisocyanate (hereinafter abbreviated as TDI) or a mixture of TDI and diphenylmethane diisocyanate (hereinafter abbreviated as MDI) has been used as an isocyanate raw material in the production of high modulus polyurethane foam.

However, TDI has a problem of deteriorating the working environment due to its high vapor pressure, high toxicity, and strong odor. Furthermore, since TDI has low reactivity with the raw material polyol, there have been problems such as low productivity and increased equipment costs.

In order to improve the above-mentioned problems faced by TDI, M
A method for producing highly elastic polyurethane foam using DI and/or its derivatives is disclosed in JP-A-53-51299.
No., JP-A-57-1, 09820, JP-A-62-11
It is proposed in No. 2616. Foams manufactured based on MDI and/or its derivatives are generally referred to as all-MDI high-modulus polyurethane foams, which provide excellent foam properties and low toxicity, making them ideal for creating a good working environment on production lines. It has excellent features such as easy maintenance, fast production speed, and high productivity.

However, the all-MDI high tensile strength polyurethane formulation has a fatal drawback in that the system flowability and the foam fluidity are extremely poor, and it is difficult to reduce the density of the foam. Therefore, halogenated hydrocarbons, such as trichloromonofluoromethane (hereinafter CFC-11
It is abbreviated as ) is used in an amount of 5 to 15 parts by weight based on the polyol, thereby ensuring liquid flowability and foam fluidity and reducing foam density. However, even at present, it is desired to further improve the all-MDI high modulus polyurethane formulation and develop a manufacturing technology for lowering the density.

In addition, among halogenated hydrocarbons, efforts have been made in recent years to reduce and further regulate the use of fluorocarbon compounds such as CFC-11, which has the danger of destroying the ozone layer. Reduce the amount of fluorocarbon compounds used as blowing agents in the production of polyurethane foam,
Instead, using more water has become an urgent and important issue. On the other hand, there are so-called substitute fluorocarbon compounds for fluorocarbon compounds such as CFC-1,1, which may cause ozone layer depletion, such as methylene chloride, dichlorotrifluoroethane, and dichloromonofluoroethane (hereinafter referred to as HCF C-1-1, respectively). 23, HCFC-141
It is abbreviated as b. ) have been proposed. However, these alternative fluorocarbon compounds still have the potential to deplete the ozone layer, and are more expensive than conventionally used fluorocarbon compounds, so they cannot be used at the same level for economic reasons. It is difficult to use in Therefore, there is a strong desire to develop a formulation that reduces the amount of fluorocarbon compounds used and instead uses a large amount of water as a blowing agent.

However, the use of large amounts of water as a blowing agent poses several technical problems. That is, in the process of forming the foam, the stability of the foam is significantly deteriorated, phenomena such as foam collapse occur, the process range is narrow, the physical properties of the foam are also deteriorated, and it becomes extremely difficult to reduce the density of the foam. Furthermore, deterioration in formability of the foam, such as cell roughness and voids, is unavoidable.

Until now, as a catalyst for all-MDI high modulus polyurethane foam, for example, triethylenediamine was used as a base catalyst, and bis(2-dimethylaminoethyl) was used as a co-catalyst.
Amine catalysts such as ethers and dimethylethanolamine have been used.

However, with these amine catalyst systems, it is not possible to lower the density of the current foam using a fluorocarbon compound as a blowing agent, and in a system in which the amount of fluorocarbon compound as a blowing agent is reduced and the amount of water is increased, It has been difficult to obtain practical high modulus polyurethane foams with low density.

[Problem to be solved by the invention] The present invention solves the following problems in the production of high elastic polyurethane foam:
To provide a manufacturing method that can achieve foam stabilization and low density, which have been problems in the past, and an industrially useful method for manufacturing highly elastic polyurethane foam that can reduce the use of fluorocarbon compounds as blowing agents. It is something.

[Means for Solving the Problems] As a result of intensive studies on high modulus polyurethane foam systems from the perspective of catalysts, the present inventors found that by using an amine compound having a specific chemical structure as a catalyst, it is possible to improve We have achieved a lower density foam, and we have also discovered the new fact that by reducing the amount of fluorocarbon compounds and increasing the amount of water, we can improve the foam stability and moldability during foaming and produce a foam with a lower density. This finding led to the completion of the present invention.

That is, the present invention provides a method for producing highly elastic polyurethane foam by reacting a polyol and a polyisocyanate in the presence of a catalyst, a blowing agent, and a foam stabilizer, in which the catalyst is at least an imidazole compound selected from the following general formula. The present invention relates to a method for producing a highly elastic polyurethane foam, characterized in that one or more of the above are used.

(In the formula, R1 is an alkyl group having 1 to 4 carbon atoms, a dimethylaminopropyl group, a benzyl group, a vinyl group, or a
3, R2 represents hydrogen, an alkyl group having 1 to 4 carbon atoms, an allyl group, a benzyl group, or a phenyl group, and R3 and R4 represent hydrogen, an alkyl group having 1 to 4 carbon atoms, or hydroxymethyl represents a group. ) [Function] The present invention will be explained in detail below.

As the catalyst of the present invention, an imidazole compound represented by the above general formula can be used.

The imidazole compound of the present invention includes 1-methylimidazole, 1,2-dimethylimidazole, ], ]4-
dimethylimidazole]-]methyl 2-ethylimidazole 1,4-dimethyl 2-ethylimidazole, 1-methyl-2-isopropylimidazole, 1-methyl-2
-phenylimidazole, 1-vinylimidazole, 1
Benzyl-2-methylimidazole, 1-(3dimethylaminopropyl)imidazole, 1-isobutyl-2-
Examples include methylimidazole and 1-n-butyl-2-methylimidazole.

More preferred examples include 1-methylimidazole, 1゜2-dimethylimidazole, ]-(]3-dimethylaminopropylimidazole, 1-isobutyl-2-methylimidazole, and ]-]〇-butyl-20methylimidazole. The amine catalyst of the present invention can be used in combination with other tertiary amino group-containing compounds as co-catalysts. Examples of other tertiary amino group-containing compounds include triethylamine, N N-dimethylcyclohexylamine, N, N, N', N'
-tetramethylethylenediamine, N, N, N', N
' -Tetramethylpropylenediamine, N, N, N'
, N'N'-pentamethyldiethylenetriamine, N
N, N', N'N'-pentamethyl-(3-aminopropyl)ethylenediamine, N, N, N'N',
N'-pentamethyldipropylenetriamine, N, N,
N', N'-tetramethylguanidine, 1,3.5
-) lis(N,N-dimethylaminopropyl)hexahydro-3-)riazine, 18-diazabicyclo[5,4
,0] undecene-7, triethylenediamine, N,
N, N'N'N'-pentamethyldiethylenetriamine, N.

N,N'N'-tetramethylhexamethylenediamine, N-methyl-N'-(2-dimethylami1))ethylpiperazine, N,N'-dimethylpiperazine, N-methylmorpholine, N-ethylmorpholine, N
, N-dimethylethanolamine, dimethylaminoethoxyethanol, N,N,N'trimethylaminoethylethanolamine, 1゜3-bis(N,N-dimethylamino)-2-propertool, bis(2-dimethylaminoethyl ) ether etc., preferably triethylenediamine and/or bis(2-dimethylaminoethyl)ether.

Further, the organic carboxylate salt of the imidazole compound, the organic carboxylate salt of other tertiary amines, and the R-containing tin compound can be appropriately used as co-catalysts as long as the catalytic function of the present invention is not lost.

The catalyst of the present invention may be prepared by using the imidazole compound alone or by mixing it with other amine catalysts, as described above.

In the mixing adjustment, if necessary, dipropylene glycol, ethylene glycol, 1,4-butanediol, water, etc. can be used as a solvent, but the amount of the solvent is not particularly limited. It is approximately 70% or less of the total amount. The catalyst produced in this manner can be used by adding it to a polyol. Also, various amine catalysts may be added separately to the polyol.

The amount of the amine catalyst used in the present invention is usually 0.02 to 10 parts by weight based on 100 parts by weight of the polyol.

The polyol used in the present invention is a known polyether polyol, polyester polyol and/or polymer polyol, more preferably a polyether polyol or a mixture of a polyether polyol and a polymer polyol. Examples of polyether polyols include polyether polyols prepared by addition reaction of ethylene oxide or propylene oxide to polyhydric alcohols such as ethylene glycol, glycerin, triethylamine, and pentaerythritol.
dbook (authored by Gunter Qertel), pages 42 to 53, and Jikai 3 No. 112616/1982. Examples of polymer polyols include polyether polyols prepared by reacting the polyether polyol with ethylenically unsaturated monomers such as butadiene, acrylonitrile, styrene, etc. in the presence of a radical polymerization catalyst.
urethane Handbook (Gunter
Examples include the polymer polyols described on pages 75 to 76 of Phys. Oertel).

The polyisocyanate used in the present invention contains at least MDI and/or a derivative thereof, and the content thereof is 50%.
In the above case, the catalytic effect of the present invention is significantly exhibited. M
Examples of DI and its derivatives include mixtures of MDI and its polymer polyphenyl-polymethylene diisocyanate, and/or diphenylmethane diisocyanate derivatives having terminal isocyanate groups. Examples of the former mixture include a 4 mixture of MDI and its derivative polyphenyl-polymethylene polyisocyanate, which is described in JP-A-53-51299. Examples of the latter diphenylmethane diisocyanate derivatives having a terminal isocyanate group include MDI, polyphenyl-polymethylene polyisocyanate, and/or mixtures thereof described in JP-A-57-109820 and JP-A-62-112616. Examples include known terminal isocyanate prepolymers obtained by reacting polyether diol or triol at room temperature or elevated temperature, optionally in the presence of a catalyst.

The isocyanate index of the present invention is not particularly limited, but generally ranges from 70 to 120.

As the halogenated hydrocarbon used as a blowing agent in the present invention, known halogenated methane and halogenated ethane can be used. Among these, CFC-11, HCFC-12
Preferred are halogenated carbons or halogenated hydrocarbons such as No. 3 and HCFC-141b. The number of parts used is 20 parts by weight or less, preferably 0 to 15 parts by weight, per 100 parts by weight of polyol. The number of wood parts as a foaming agent is polyol 100
The amount is 2 parts by weight or more, preferably 2.5 to 5 parts by weight, based on the weight of the heavy base, but when water is used alone, it is preferably 3 parts by weight or more. The amounts of water and chlorofluorocarbon used can be appropriately selected depending on the desired foam density.

In the present invention, a crosslinking agent or a chain extender can be added if necessary. Examples of crosslinking agents or chain extenders include low molecular weight polyhydric alcohols such as ethylene glycol, 1,4-butanediol, glycerin, etc., low molecular weight amine polyols such as jetanolamine, triethanolamine, etc., or polyamines such as ethylenediamine, Examples include xylylene diamine, methylenebisorthochloroaniline, secondary diamines such as aliphatic and cycloaliphatic secondary diamines, polyoxybupopyrine secondary diamines, and aromatic secondary diamines.

If necessary, organic silicone compounds, colorants, flame retardants, anti-aging agents and other known additives can also be used as surfactants. The types and amounts of these additives can be used within the commonly used ranges as long as they do not deviate from known formats and procedures.

[Effects of the Invention] According to the present invention, it has become possible to reduce the density of high-elastic polyurethane foam using a fluorocarbon compound as a blowing agent, which has been difficult until now. Furthermore, it has become possible to improve foam stability and moldability in formulations that reduce the amount of fluorocarbon compounds and increase the amount of water, and also to achieve lower density.

[Examples] The present invention will be described below based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

Examples 1 to 10 and Comparative Examples 1 to 7 The following formulations were used for the Oil MDI high modulus polyurethane foam system. The foam stability, moldability, and physical properties of the foam during foaming were determined by the following method by changing the amount of water and halogenated hydrocarbon as a blowing agent and the type of catalyst, and under specified foaming conditions. It was measured with The results are shown in Tables 1 and 2.

a, Formulation 1) Polyether polyol, OH value - 28 mg KOH/g (mixture of tetraol and triol, average molecular ff 17000, ethylene oxide content 8-15%) 2) Silicone surfactant (manufactured by Toray Silicone Co., Ltd., 5RX-274C) 3) Explanation of catalyst abbreviations in the table DMIZ, 1,2-dimethylimidazole NMIZ, 1
-Methylimidazole DMAP IZ, 1-(3-dimethylaminopropyl)imidazole IBIZ, 1-isobutyl-2-methylimidazole TEDA-L33; ) 33% lyethylenediamine dipropylene glycol solution (manufactured by Tosoh Corporation Seikinsha) TOYOCAT- MR, Tetramethylhexamethylene diamine (manufactured by Tosoh Corporation) TOYOCAT-NP, 4-methyl-1-(2-dimethylamino 4) isocyanate dimethyl) piperazine (manufactured by Tosoh Corporation) NGO concentration -25.0%, diphenylmethane diisocyanate 3. Foaming conditions Raw material liquid temperature Stirring speed Mold Mold temperature 20 ± 1°C 6000 rpm (5 seconds) Foaming in an aluminum box (dimensions: 25 x 25 x 25 cm) 40°C measurement.

・Reactivity] 9 Cream time: 0 time from the start of foaming (seconds) Gel time: Time for resin (stringing) to form (seconds) Rise time: Time for the foam to reach its maximum foaming height (seconds) ・Foam stability Evaluation was made based on the size of the form depression after the rise time.

・Foam expansion ratio The value obtained by dividing the foam's maximum foaming height by the foam weight (c
m/g) The larger this value, the greater the foaming effect of water and the lower the density of the foam.

・Foam density 20 x 20 x 10 cm from the center of the form
Take a test piece with the size of and measure the density.

・Evaluation of moldability The state of cell roughness and voids in the foam was observed and ranked in five stages.

1 0 1: Almost none 2: Small 3: Medium 4: Large 5: Very large As is clear from Tables 1 and 2, in the formulation where the amount of fluorocarbon was reduced as a blowing agent and the amount of water was increased, imidazole compound was used as a catalyst. By using this material, it was possible to stabilize the foam and produce a molded foam with low density and excellent moldability.

On the other hand, as seen in Comparative Examples 1 to 7, with conventional catalysts such as triethylenediamine, foams with high density and moldability with large cell roughness were obtained. For this reason, with these catalysts, it is difficult to reduce fluorocarbons by increasing the amount of water used.

nine

Claims (6)

[Claims] (1) In a method for producing polyurethane foam by reacting a polyol and a polyisocyanate in the presence of a catalyst, a blowing agent, and a foam stabilizer, as the polyisocyanate,
a mixture with at least diphenylmethane diisocyanate and/or its derivatives, the blowing agent is water or water and a halogenated hydrocarbon, and the amount of the polyol is 10
0 parts by weight, water is at least 2 parts by weight and halogenated hydrocarbon is at most 20 parts by weight, and the catalyst has at least the following general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R^1 is carbon number 1 ~4 alkyl group, dimethylaminopropyl group, benzyl group, vinyl group or carbon number 1
~3 represents a hydroxyalkyl group, R^2 is hydrogen,
Represents an alkyl group, allyl group, benzyl group, or phenyl group having 1 to 4 carbon atoms, and R^3 and R^4 are hydrogen and have 1 carbon number.
~4 alkyl group or hydroxymethyl group. ) A method for producing a highly elastic polyurethane foam, characterized in that one or more selected from the imidazole compounds shown below are used. (2) The production method according to claim (1), wherein the polyisocyanate is a mixture with diphenylmethane diisocyanate and/or a derivative thereof, and has an isocyanate index of 70 to 120. (3) The production method according to claim (1) or (2), wherein the polyol is a polyether polyol or a mixture of a polyether polyol and a polymer polyol. (4) Claim No. 1 in which the halogenated hydrocarbons are trichloromonofluoromethane (CFC-11), dichlorotrifluoroethane (HCFC-123), and dichloromonofluoroethane (HCFC-141b)
The manufacturing method according to any one of Items to (3). (5) The blowing agent is water and the amount of the polyol is 100%
The manufacturing method according to any one of claims (1) to (3), wherein the amount of water is 3.0 parts by weight or more based on parts by weight. (6) The imidazole compound includes at least 1-methylimidazole, 1,2-dimethylimidazole, 1-
(3-dimethylaminopropyl)imidazole, 1-isobutyl-2-methylimidazole, 1-n-butyl-
The manufacturing method according to claim (1), characterized in that one or more types selected from 2-methylimidazole are used.