JPH09124763A - Production of polyurethane foam molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a skinned polyurethane foam molding with an improved moldability without using R-11 by reacting a high-molecular active hydrogen compd. component contg. a specified amt. of a specific polyoxyalkylene polyol with a chain extender and a polyisocyanate compd. in the presence of a catalyst and a blowing agent mainly comprising water and/or an inert gas in an airtight mold. SOLUTION: A high-molecular active hydrogen compd. component used here is a polyoxyalkylene polyol having a hydroxyl functionality of 2-8, a hydroxyl value of 3-60mgKOH/g, and a total unsaturation of 0.07meq/g or lower or is a polymer polyol contg. the above-mentioned polyoxyalkylene polyol as the matrix component, subject to the condition that at least a part of the polyoxyalkylene polyol comprises 20-100wt.% polyoxyalkylene polyol obtd. by the ring-opening polymn. of an alkylene oxide in the presence of a Cs or Rb catalyst and an initiator and 0-80wt.% other polyoxyalkylene polyol and contains 80wt.% or higher polyoxyalkylene polyol having a hydroxyl functionality of 2-8 and a hydroxyl value of 3-60mgKOH/g.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polyurethane foam molded article with a skin.

[0002]

2. Description of the Related Art Polyurethane foam molded products with integral skin have a skin layer integrally molded with the foam layer and have excellent elasticity and tactile sensation, so they can be used for automobile interior parts such as steering wheels, crash pads, headrests and armrests. It is used a lot.

A polyurethane foam molded product with integral skin is formed by forming an elastomeric skin layer by suppressing foaming of the polyurethane raw material in the surface layer portion which is in contact with the inner wall of the mold when molding the polyurethane foam in the closed mold. Molded. Integral skin is usually
It means that the expansion ratio of the skin layer increases from the surface of the molded product toward the inside (that is, the density decreases), and in most cases, the boundary between the skin layer and the foam layer is not clear.

The principle of forming an integral skin is considered as follows. That is, when foaming is carried out in a molding die using a raw material containing a freon-based foaming agent having a relatively high boiling point as a foaming agent, the reaction heat is absorbed by the molding die at the same time as molding is performed at the surface layer portion in contact with the inner wall of the molding die. It is considered that the CFC-based foaming agent could not be vaporized due to the mold internal pressure and the integral skin layer was formed.

Therefore, when producing a polyurethane foam with integral skin, not only it is necessary to select a suitable polyol and isocyanate as raw materials, but also the selection of a blowing agent is very important. 30-4
A foaming agent that does not vaporize near the inner wall of the mold at a temperature of 0 ° C., that is, has a boiling point not higher than the mold temperature is required. For that reason, conventionally, only trichlorofluoromethane (R-11) which is a chlorofluorocarbon type foaming agent has been used.

[0006]

However, chlorofluorocarbon type foaming agents such as R-11 may destroy the earth's protective ozone layer by an ozone depletion chain reaction, and it is desired to reduce the amount used. There is.

Water which reacts with isocyanate compounds to release carbon dioxide has been used as an alternative to chlorofluorocarbon based blowing agents. However, there are drawbacks such as embrittlement of the foam to be produced, and economical disadvantage because the amount of polyisocyanate compound used increases.
Further, in the method for producing a polyurethane foam with integral skin, it is difficult for carbon dioxide, which has a low boiling point and is a gas at room temperature, to form an integral skin.

[0008]

Means for Solving the Problems The present inventor does not use a chlorofluorocarbon-based foaming agent such as R-11, and uses water or an inert gas such as air or nitrogen gas as a foaming agent to form a skin It has been found that a polyurethane foam molded article can be manufactured.

The polyurethane foam molded article with a skin in the present invention is a molded article in which a non-foamed skin layer of the same polyurethane material as the polyurethane foam is integrally formed at the same time when the polyurethane foam is formed during the polyurethane foam molding. Say. The skin in the present invention means not only integral skin but also skin having a relatively clear boundary with the foam layer as compared with integral skin.

The present invention is the following invention which solves the above-mentioned problems.

80% by weight or more of a polyoxyalkylene polyol having 2 to 8 hydroxyl groups and a hydroxyl value of 3 to 60 (mgKOH / g) consisting of 20 to 100% by weight of (a) below and 0 to 80% by weight of (b) below. Reaction of the contained high-molecular weight active hydrogen compound, chain extender, and polyisocyanate compound in a closed mold in the presence of a blowing agent containing water and / or an inert gas as a main component and a catalyst. A method for producing a polyurethane foam molded article with a skin, comprising the step of producing a polyurethane foam molded article with a skin.

(A): A polyoxyalkylene polyol having 2 to 8 hydroxyl groups, a hydroxyl value of 3 to 60 (mgKOH / g), and a total degree of unsaturation of 0.07 (meq / g) or less. , Or a polymer-dispersed polyol having a polyoxyalkylene polyol as a matrix, wherein at least a part of the polyoxyalkylene polyol is subjected to ring-opening polymerization of alkylene oxide in the presence of an initiator using a cesium-based or rubidium-based catalyst. A polyoxyalkylene polyol obtained by. (B): A polyoxyalkylene polyol other than the above (a), or a polymer-dispersed polyol having the polyoxyalkylene polyol as a matrix.

In the present invention, when a polyoxyalkylene polyol having a low degree of total unsaturation is used, the reason why a skin is formed even if foaming by a non-condensable gas such as carbon dioxide is not clear. When the unsaturation degree of the raw material polyoxyalkylene polyol becomes low, a rapid temperature rise occurs in the latter half of the polyurethane foam formation reaction, and the temperature difference between the surface of the mold and the inside of the foam becomes large. Due to the fact that it is remarkable when a catalyst and an organometallic catalyst are used together, a resin layer precedes the formation of a skin layer on the surface of the mold, and then foaming and resinification occur inside to form a foam layer. Expected to be done.

When the unsaturation degree of the polyoxyalkylene polyol is low, the amount of unsaturated monool contained in the polyoxyalkylene polyol is low, that is, the true average number of functional groups is higher than that of the polyoxyalkylene polyol having a high unsaturation degree. This may increase the number of cross-linking points of the polyurethane and increase the molecular weight to increase the resin strength, which may suppress foaming in the skin layer once formed.

Generally speaking, the lower the hydroxyl value of the polyoxyalkylene polyol (ie, the higher the molecular weight), the higher the degree of unsaturation thereof. Because
The lower the hydroxyl value, the larger the amount of the oxyalkylene group having 3 or more carbon atoms, which is the main oxyalkylene group of the polyoxyalkylene polyol, particularly the oxypropylene group. Therefore, the alkylene oxide having 3 or more carbon atoms at the time of its production. This is because the reaction amount of is increased, and along with that, many side reactions of the alkylene oxide (reactions that generate an unsaturated group) also occur.

In order to give priority to the resinification reaction over the foaming reaction, lower the degree of unsaturation of the polyoxyalkylene polyol, that is, reduce the amount of unsaturated monool to obtain a higher degree of unsaturation. In comparison, it is also effective to increase the true average number of functional groups and increase the molecular weight of the polyoxyalkylene polyol.

Production of a polyurethane foam molded article with a skin using a polyoxyalkylene polyol having a low total degree of unsaturation such as (a) is described in, for example, Japanese Patent Application Laid-Open No. 5-305629 filed by the present applicant. ing.

However, when the polyoxyalkylene polyol obtained by using the complex metal cyanide complex was used, the fluidity of the raw material was poor. Therefore, molding defects (air voids, suring, etc.) of products with large and complicated shapes were observed.

The present inventor has found that when a polyoxyalkylene polyol obtained by using a cesium-based or rubidium-based catalyst is used as a part of a polyoxyalkylene polyol having a low total unsaturation degree, the fluidity can be significantly improved. It was It was also found that the improvement in fluidity can dramatically improve the molding defects (air voids, shrinks, etc.) of products having large and complicated shapes.

It is considered that one of the reasons for this is the difference in viscosity. That is, a polyoxyalkylene polyol obtained by using a complex metal cyanide complex as a catalyst is compared with a polyoxyalkylene polyol obtained by using a cesium-based or rubidium-based catalyst and compared with a polyoxyalkylene polyol having the same molecular weight. When this was done, the viscosity tended to increase slightly. This tendency was remarkable as the molecular weight was increased.

The more preferred hydroxyl value of (a) is 3-40.
(MgKOH / g), the degree of unsaturation is 0.05 (meq /
g) Below. More preferred (a) has a hydroxyl value of 3
~ 35 (mgKOH / g), degree of unsaturation 0.04 (meq
/ G) The following polyoxyalkylene polyols.
The number of hydroxyl groups (the number of hydroxyl groups per molecule) is 2 to 8
And particularly preferably 2 to 6. The viscosity of the polyoxyalkylene polyol (a) is 3000 cP at 25 ° C.
The following is preferred. In addition, (a) may be a mixture of two or more polyxyalkylene polyols,
In that case, the average degree of unsaturation, the hydroxyl value, and the range of the number of hydroxyl groups are as described above.

Further, (a) is a polyoxyalkylene polyol mainly containing an oxyalkylene group having 3 or more carbon atoms. Since an oxyalkylene group having 2 carbon atoms, that is, an oxyethylene group, does not cause a side reaction to generate an unsaturated group in its formation reaction (addition reaction of ethylene oxide), a polyoxyalkylene polyol having a high proportion of oxyethylene groups is originally used. Unsaturation is low. However, a polyurethane foam molded article with a skin obtained by using a polyoxyalkylene polyol having a high proportion of oxyethylene groups as a main raw material does not have practically good physical properties. Therefore, (a) is preferably a polyoxyalkylene polyol mainly containing an oxyalkylene group having 3 or more carbon atoms, particularly an oxypropylene group derived from 1,2-propylene oxide.

As (a), the content of oxyalkylene group having 3 or more carbon atoms, particularly oxypropylene group, is 75.
Preference is given to polyoxyalkylene polyols of more than weight%. Further, although it may contain an oxyethylene group,
The content is preferably 20% by weight or less. Further, the oxyethylene group contained is preferably located at the end of the polyoxyalkylene chain. Since the hydroxyl group bonded to the terminal oxyethylene group is highly reactive, a polyoxyalkylene polyol having about 3% by weight or more, particularly 5% by weight or more, of oxyethylene groups at the terminal is preferable.
Preferred (a) is a polyoxyalkylene polyol mainly containing an oxypropylene group, that is, a polyoxypropylene-based polyol having an oxypropylene group content of 75% by weight or more and an oxyethylene group content of 3 to 25% by weight.

(A) may also be a polymer-dispersed polyol having the above-mentioned polyoxyalkylene polyol as a matrix, and a mixture of the polymer-dispersed polyol and this polyoxyalkylene polyol. The polymer-dispersed polyol is a dispersion in which fine particles of a polymer such as a vinyl polymer are dispersed in the polyol, and is obtained, for example, by polymerizing a vinyl monomer such as acrylonitrile or styrene in the polyol.

Generally, the polyoxyalkylene polyol used as a raw material for polyurethane is an alkylene oxide such as propylene oxide in the presence of an initiator such as polyhydric alcohol using a sodium or potassium catalyst such as sodium hydroxide or potassium hydroxide. Is produced by ring-opening addition polymerization. However, this production method using a sodium-based or potassium-based catalyst easily causes a reaction in which a monol having an unsaturated group is by-produced, and it is difficult to produce a polyoxyalkylene polyol having a low unsaturation degree and a low hydroxyl value. is there.

As a catalyst for producing a polyoxyalkylene polyol having a low degree of unsaturation and a low hydroxyl value, a cesium-based or rubidium-based catalyst, a metal porphyrin (JP-A-61-197631), and a LiPF6 (JP-A-60-19).
7726), a complex metal cyanide complex (Japanese Patent Publication No. 59-1).
5336, U.S. Pat. No. 3,929,505), a complex of a metal and a chelating agent having a tridentate or higher coordination (JP-A-60-197).
726) and so on.

In the present invention, the proportion of the polyoxyalkylene polyol obtained by using the cesium-based or rubidium-based catalyst in the polyoxyalkylene polyol (a) is preferably 30 to 100% by weight. In the present invention, the cesium-based or rubidium-based catalyst means a catalyst containing rubidium, cesium or a compound thereof.

As a polyoxyalkylene polyol having a low unsaturation and a low hydroxyl value, a polyoxyalkylene polyol obtained by using a complex metal cyanide complex is used to produce a polyurethane foam molded article with a skin as described above. As is known, the polyoxyalkylene polyol obtained using the complex metal cyanide complex catalyst and the polyoxyalkylene polyol obtained using the cesium-based catalyst are the same even if the conditions other than the catalyst are the same. The physical properties of the two are different.

That is, even if the type of initiator, the type and amount of alkylene oxide, and the hydroxyl value and the degree of unsaturation of the resulting polyoxyalkylene polyol are the same, the physical properties such as water affinity and viscosity of the polyoxyalkylene polyol are different, As a result, the resulting polyurethane foam with skin has different physical properties.

It is speculated that this is because the reaction mode of the alkylene oxide (for example, propylene oxide) having an asymmetric molecular structure differs depending on the catalyst. That is, the hydroxyl groups newly generated by the ring-opening addition polymerization of propylene oxide are almost all secondary hydroxyl groups in the case of the alkali catalyst. On the other hand, in the case of the complex metal cyanide complex catalyst, primary hydroxyl groups are produced in a nonnegligible proportion. Therefore, the polyoxyalkylene chain having a large number of oxypropylene groups obtained by using the double metal cyanide complex catalyst contains oxypropylene groups having different bonding modes, which causes the above-mentioned difference in physical properties. It is speculated that it will get worse.

The polyoxyalkylene polyol obtained by using the cesium-based or rubidium-based catalyst according to the present invention is characterized by having a lower viscosity than the polyoxyalkylene polyol obtained by using the above-described double metal cyanide complex catalyst. Have. Further, the complex metal cyanide complex catalyst has a drawback that an oxyethylene group cannot be introduced into the end of the polyoxyalkylene polyol, but the cesium-based or rubidium-based catalyst is also characterized in that the terminal oxyethylene conversion is easy.

The use of a cesium-based or rubidium-based catalyst does not form an oxyalkylene group having a different bonding mode as one of the alkali catalysts. Further, unlike conventional alkali catalysts such as sodium-based catalysts and potassium-based catalysts, a polyoxyalkylene polyol having a low degree of unsaturation is produced.

(B) is a polyoxyalkylene polyol other than the polyoxyalkylene polyol of (a) above, and a polymer-dispersed polyol having the polyoxyalkylene polyol as a matrix. The number of hydroxyl groups of this polyol is 2 to 8, and the hydroxyl value is 20 to 11
0 is preferred. The total degree of unsaturation exceeds the above range (a) when the hydroxyl value is 60 or less, and the hydroxyl value is 6 or less.
Those exceeding 0 are not particularly limited. Such polyoxyalkylene polyol is produced using a sodium-based or potassium-based catalyst.
The total degree of unsaturation of the polyoxyalkylene polyol (b) is usually 0.1 (meq / g) or less.

The polyoxyalkylene polyol (b) is preferably a polyoxyalkylene polyol mainly containing an oxyalkylene group having 3 or more carbon atoms, particularly an oxypropylene group. The content of the oxyalkylene group having 3 or more carbon atoms is preferably 55% by weight or more. When containing oxyethylene groups, the oxyethylene group content is 4
It is preferably 0% by weight or less, and at least a part thereof is preferably present at the end of the polyoxyalkylene chain. More preferable polyoxyalkylene polyol (b) is a polyoxypropylene-based polyol having an oxypropylene group content of 55% by weight or more and an oxyethylene group content of 3 to 40% by weight.

As the polyoxyalkylene polyol (b), various polyoxyalkylene polyols other than the above can be used. For example, a polyoxyalkylene polyol having a higher hydroxyl value, a polyoxyalkylene polyol having a higher oxyethylene group content, a polyoxyalkylene polyol not containing an oxyethylene group, or an oxyalkylene group having 3 or more carbon atoms other than oxypropylene group is used. There are mainly polyoxyalkylene polyols and the like. Even if used, these polyoxyalkylene polyols are preferably used in a smaller amount than the above polyoxypropylene-based polyol. Usually, these polyols are preferably used in combination with the above polyoxypropylene-based polyol. Even if used, the amount of these polyols is preferably 30% by weight or less based on the total polyoxyalkylene polyol.

The above-mentioned polyoxyalkylene polyols (a) and (b) are generally produced as follows. That is, it is obtained by adding at least one alkylene oxide to a polyvalent initiator in the presence of a catalyst.

Examples of the alkylene oxide include alkylene oxides having 2 or more carbon atoms, specifically, ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide and styrene oxide. In particular, 1,2-propylene oxide,
At least one of 1,2-butylene oxide and 2,3-butylene oxide, or a combination of at least one of them and ethylene oxide is preferable.

As the polyvalent initiator used when producing the above polyoxyalkylene polyol, there are polyhydric alcohols, polyhydric phenols, polyamines, alkanolamines and the like. For example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, glycerin, trimethylolpropane, pentaerythritol,
Examples thereof include diglycerin, dextrose, sucrose, bisphenol A, ethylenediamine, and polyoxyalkylene polyol having a lower molecular weight than the intended product obtained by adding alkylene oxide to these. These initiators may be used alone or in combination of two or more. Particularly preferred polyhydric initiators are polyhydric alcohols.

The hydroxyl group in the polyoxyalkylene polyol preferably contains a highly reactive hydroxyl group, that is, a primary hydroxyl group in a high proportion. Especially,
In order to carry out the reaction injection molding method that requires the use of highly reactive raw materials, it is usually necessary that an oxyethylene group be present at the terminal of the molecular chain of the polyoxyalkylene polyol.

Such a polyoxyalkylene polyol can be obtained by adding ethylene oxide after adding an alkylene oxide having a carbon number of 3 or more such as 1,2-propylene oxide to a polyvalent initiator. The oxyethylene group may also be present inside the polyoxyalkylene chain. When an oxyethylene group is present at the polyoxyalkylene chain end for the purpose of improving reactivity,
The content of the oxyethylene group is usually 3% by weight or more, and particularly 5% by weight or more.

The higher the content of oxyethylene groups in the polyoxyalkylene polyol, the more hydrophilic the resulting polyurethane foam with skin. In the case of a molded article used outdoors such as an air spoiler for automobiles, if the hydrophilicity is too high, the water absorption will be high and the dimensional stability will be lowered, such being undesirable. Therefore, the content of oxyethylene groups in the total polyoxyalkylene polyol is preferably 35% by weight or less, and particularly preferably 25% by weight or less. Further, in that case, it is preferable that most of the oxyethylene group is present at the terminal portion of the molecular chain. The upper limit of the oxyethylene group content is not limited to this, for applications where the hydrophilicity of the polyurethane foam with skin is not required to be low.

As described above, the polymer-dispersed polyol having the polyoxyalkylene polyol as a matrix can be used as (a) or (b) in the present invention. Further, it may be a polymer-dispersed polyol produced by using a mixture of the polyoxyalkylene polyols of (a) and (b) as a matrix. The polymer-dispersed polyol is a dispersion in which polymer particles are stably dispersed in the matrix, and examples of the polymer include an addition polymer-based polymer and a condensation polymer-based polymer.

The fine polymer particles in the polymer-dispersed polyol are addition polymerization polymers such as homopolymers and copolymers of acrylonitrile, styrene, alkyl methacrylate, alkyl acrylate and other vinyl monomers, and condensation polymerization of polyesters, polyureas, polyurethanes, melamine resins and the like. It consists of a polymer. Due to the presence of the polymer fine particles, the hydroxyl value of the entire polymer-dispersed polyol is generally lower than the hydroxyl value of the matrix polyol. Therefore, the total hydroxyl value of the polymer-dispersed polyol having the polyoxyalkylene polyol of (a) as a matrix is 60 or less, particularly 3
It is preferable that it is ~ 35.

The content of the fine polymer particles in the polymer-dispersed polyol or the mixture thereof and the polyoxyalkylene polyol is usually 60% by weight or less, and particularly 40% by weight or less. The amount of the polymer fine particles does not need to be particularly large, and even if it is too large, it is not inconvenient except for the economic aspect. In most cases, 20% by weight or less is sufficiently effective. The presence of polymer particles in the polyoxyalkylene polyol is not essential, but the presence thereof is effective for improving the hardness, air permeability and other physical properties of the foam.

The polyoxyalkylene polyol in the present invention may be the above (a) alone or may be composed of (a) and (b). The combination is (a) 20 to 100% by weight and (b) with respect to the total of (a) and (b).
It consists of 0 to 80% by weight. More preferably, (a) 40
.About.100% by weight and (b) 0 to 60% by weight. More preferably, (a) 70-100 wt% and (b) 0-
It consists of 30% by weight. The average hydroxyl value of the mixture [both represented by (a + b) below] is 3 to 60 (mgKOH /
g). More preferable average hydroxyl value of (a + b) is 3 to 40 (mgKOH / g). Further, as described above, the average oxyethylene group content of (a + b) is preferably 35% by weight or less, and particularly preferably 25% by weight or less.

Further, polyoxyalkylene polyol (a
The total unsaturation degree of + b) is preferably 0.07 (meg / g) or less. In particular, it is preferably 0.065 (meg / g) or less.

The high molecular weight active hydrogen compound, which is one of the main raw materials for polyurethane, is a compound having two or more active hydrogen-containing groups capable of reacting with a hydroxyl group, a primary amino group, a secondary amino group and other isocyanate groups. . In the present invention, the high molecular weight active hydrogen compound is a compound having a molecular weight of 600 or more. The high molecular weight active hydrogen compound in the present invention contains 80% by weight or more of the above (a + b). Other high molecular weight active hydrogen compounds may be contained, but the amount is 20% by weight or less.

In the present invention, a high molecular weight polyol other than the essential component polyoxyalkylene polyol (a + b) or another high molecular weight active hydrogen compound can be used in combination as an optional component, but its use is not essential. However, it can be used for the purpose of improving the physical properties of the polyurethane foam with skin, or for other purposes. For example, it may be preferable to use highly hydrophobic, high molecular weight polyols such as hydroxyl-containing polybutadiene to reduce the hydrophilicity of skinned polyurethane foams.

As such a high molecular weight polyol, the average molecular weight per hydroxyl group is 400 or more, particularly 80.
0 or more and the average number of hydroxyl groups per molecule is 1.6
Polyols of 4 are preferred. The average molecular weight per hydroxyl group is preferably 10,000 or less. Such high molecular weight polyols include, for example, hydroxyl group-containing hydrocarbon polymers such as hydroxyl group-containing polybutadiene, polyester polyols and polyoxytetramethylene polyols.

As another high molecular weight active hydrogen compound, a high molecular weight active hydrogen compound having one or more primary amino groups or secondary amino groups can be used in combination. This active hydrogen compound has two or more functional groups selected from a hydroxyl group, a primary amino group, and a secondary amino group, and at least one of them is a primary amino group or a secondary amino group. The amino group-containing polyoxyalkylene compounds described above are preferable.

As such an amino group-containing polyoxyalkylene compound, for example, a part or all of the hydroxyl groups of a polyoxyalkylene polyol having a molecular weight of 600 or more may be a primary amino group, a secondary amino group, or such an amino group. There is a compound obtained by converting into an organic group having.
Particularly preferred is an amino group-containing polyoxyalkylene compound obtained by converting a part or all of the hydroxyl groups of polyoxypropylene polyol into primary amino groups. Further, a compound obtained by hydrolyzing an isocyanate group of a prepolymer having an isocyanate group at a terminal obtained by reacting a polyoxyalkylene polyol with an excess equivalent amount of a polyisocyanate compound to convert it into an amino group can also be used.

The molecular weight per functional group of these high molecular weight active hydrogen compounds is 400 or more, particularly 800 or more, and the number of functional groups per molecule is preferably 2-8. The molecular weight per functional group is preferably 10,000 or less.

In the present invention, a chain extender is used. The chain extender refers to a compound having a molecular weight of less than 600 and having two or more active hydrogen-containing groups capable of reacting with a hydroxyl group, a primary amino group, a secondary amino group and other isocyanate groups. Especially,
A compound having two or more functional groups selected from a hydroxyl group, a primary amino group, and a secondary amino group and having a molecular weight of 400 or less is preferable. You may use together 2 or more types of chain extenders. The chain extender is used in an amount of 1 to 30 parts by weight, preferably 1 to 15 parts by weight, per 100 parts by weight of the high molecular weight active hydrogen compound.

The polyol type chain extender having a hydroxyl group is
It is preferable to have 2 to 4 hydroxyl groups. Examples of the polyol chain extender include polyhydric alcohols and polyols such as low molecular weight polyoxyalkylene polyols obtained by adding alkylene oxides to polyhydric alcohols and the like, and polyols having a tertiary amino group.

Specific examples of the polyol chain extender include, but are not limited to, the compounds exemplified below. Preferred are ethylene glycol and 1,4-butanediol.

Ethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, triethanolamine,
N-alkyldiethanolamine, bisphenol-A
-Alkylene oxide adducts.

A compound having one amino group selected from primary amino groups and secondary amino groups and one or more hydroxyl groups can also be used as a chain extender. Examples of such chain extenders include monoethanolamine, diethanolamine, and monoisopropanolamine.

Amine chain extenders having two or more amino groups selected from primary amino groups and secondary amino groups include aromatic polyamines, aliphatic polyamines and alicyclic polyamines.

The aromatic polyamine is preferably an aromatic diamine. As the aromatic diamine, an aromatic diamine having at least one substituent selected from an alkyl group, a cycloalkyl group, an alkoxy group, an alkylthio group and an electron-withdrawing group in an aromatic nucleus to which an amino group is bonded is preferable. Particularly preferred are diaminobenzene derivatives. It is preferable that 2 to 4 of the above-mentioned substituents other than the electron-withdrawing group are bonded to the aromatic nucleus to which the amino group is bonded, and particularly, at least one ortho position relative to the binding site of the amino group, and preferably all of them. It is preferably bound.

It is preferable that one or two electron-withdrawing groups are bonded to the aromatic nucleus to which the amino group is bonded. The electron withdrawing group and the other substituent may be bonded to one aromatic nucleus.

The alkyl group, alkoxy group and alkylthio group preferably have 4 or less carbon atoms, and the cycloalkyl group is preferably a cyclohexyl group. As the electron-withdrawing group, a halogen atom, a trihalomethyl group, a nitro group, a cyano group, an alkoxycarbonyl group and the like are preferable, and a chlorine atom, a trifluoromethyl group and a nitro group are particularly preferable.

Examples of the aliphatic polyamines include diaminoalkanes having 6 or less carbon atoms, polyalkylene polyamines, and polyamines obtained by converting part or all of the hydroxyl groups of low molecular weight polyoxyalkylene polyols into amino groups. Furthermore, a polyamine having an aromatic nucleus such as an aromatic compound having two or more aminoalkyl groups, an aromatic compound having two or more aminoalkyl groups in total, and these aromatic compounds having the above-mentioned substituents is used. You can also do it.

The alicyclic polyamine includes cycloalkane having two or more amino groups and / or aminoalkyl groups.

Specific examples of the amine-based chain extender are shown below, but the invention is not limited thereto. Particularly preferred are diethyltoluenediamine [that is, one or a mixture of 1-methyl-3,5-diethyl-2,4- (or 2,6) -diaminobenzene], dimethylthiotoluenediamine, monochlorodiaminobenzene, It is a diaminobenzene derivative such as trifluoromethyldiaminobenzene.

1-methyl-3,5-diethyl-2,4-
(Or 2,6) -diaminobenzene, monochloro-
p-diaminobenzene, 1-methyl-3,5-bis (methylthio) -2,4- (or 2,6) -diaminobenzene, 1-trifluoromethyl-3,5-diaminobenzene, 1-trifluoromethyl -4-chloro-3,5
-Diaminobenzene, 2,4-toluenediamine, 2,
6-toluenediamine, bis (3,5-dimethyl-4-
Aminophenyl) methane, 4,4'-diaminodiphenylmethane, ethylenediamine, 1,4-diaminohexane, 1,3-bis (aminomethyl) cyclohexane, isophoronediamine.

Another main raw material for polyurethane is a polyisocyanate compound. As the polyisocyanate compound, aromatic, alicyclic or aliphatic polyisocyanates having two or more isocyanate groups, and those 2
There are mixtures of more than one type, and modified polyisocyanates obtained by modifying them.

Specifically, for example, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymethylene polyphenyl isocyanate (common name: crude MDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPD).
I), polyisocyanates such as hexamethylene diisocyanate (HMDI), prepolymer-type modified products thereof, nurate modified products, urea modified products, and carbodiimide modified products. A preferred polyisocyanate compound is a mixture of TDI, modified MDI, crude MDI, and an aromatic polyisocyanate containing one of them as a main component.

The amount of the polyisocyanate compound used is usually 0.8 times or more equivalent to the total equivalent amount of the high molecular weight active hydrogen compound and the chain extender. When the isocyanate group-multimerizing catalyst is not used, the upper limit is usually 1.5 times equivalent, preferably 1.3 times equivalent. The amount of the polyisocyanate compound used in the present invention is preferably 0.8 to 1.3 times the equivalent amount based on the total equivalent amount of the high molecular weight active hydrogen compound and the chain extender.

The blowing agent used in the present invention is a blowing agent containing water and / or an inert gas as a main component.
Water reacts with the polyisocyanate compound to generate carbon dioxide. The inert gas includes air and nitrogen gas.
Water and an inert gas may be used alone or in combination, or may be used in combination with another foaming agent. When used in combination with another foaming agent, the gas amount (volume) generated by the foaming agent in the present invention is preferably larger than the gas amount generated by the other foaming agent.

The amount of the foaming agent such as water used is not particularly limited, but 0.1 to 10 parts by weight, particularly 0.1 to 5 parts by weight is suitable for 100 parts by weight of the high molecular weight active hydrogen compound. The amount of the foaming agent, including the following foaming agents that can be used in combination, can be adjusted to an appropriate amount according to the desired requirements such as the expansion ratio.

In the present invention, the foaming agent which can be used in combination is R-
Chlorofluorocarbon (CFC) based blowing agents such as 11 are not preferred. When a low-boiling organic compound-based blowing agent is used in combination, hydrochlorofluorocarbon (HCF
C) type foaming agent, hydrofluorocarbon (HFC) type foaming agent, hydrochlorocarbon (HCC) type foaming agent,
It is preferable to use a hydrocarbon foaming agent or the like. For example, 1,1-dichloro-1-fluoroethane, 1,1-dichloro-2,2,2-trifluoroethane, methylene chloride, butane, pentane, isopentane,
Cyclopentane, hexane, acetone, cellosolve and the like.

The amount of the foaming agent which can be used in combination is not particularly limited, but when used in combination with water, it is suitable to be up to 12 parts by weight, particularly up to 8 parts by weight with respect to 100 parts by weight of the high molecular weight active hydrogen compound. is there.

In the present invention, it is not essential to use a foaming agent that can be used in combination as described above, particularly a low-boiling organic compound-based foaming agent. For example, a good polyurethane foam with skin can be obtained by using substantially only water as a foaming agent. Can be manufactured.

When reacting the active hydrogen compound and the polyisocyanate compound, it is necessary to use a catalyst. As the catalyst used in the present invention, rather than the reaction of water and polyisocyanate called foaming reaction, rather than the active hydrogen-containing group and isocyanate group of polyoxyalkylene polyol or chain extender called resinification reaction Compounds that accelerate the reaction are mainly used as catalysts.

As the catalyst for promoting the resinification reaction, a metal compound catalyst or a certain amine catalyst is effective. Amine-based catalysts that are mainly used in the production of polyurethane foam are catalysts that mainly promote the foaming reaction, but some amine-based catalysts have the action of promoting the resinification reaction rather than the foaming reaction. As the amine-based catalyst used in the present invention, an amine-based catalyst having an action of promoting such a resin formation reaction is used. A catalyst that promotes a relatively small amount of foaming reaction can be used together with such an amine catalyst or a metal compound catalyst.

When an amine-based catalyst having a function of promoting the resinification reaction is used, the amount thereof is 5 parts by weight or less, particularly 0.1 to 3 parts by weight, based on 100 parts by weight of the high molecular weight active hydrogen compound. is there. The amount of the metal compound catalyst is 2 parts by weight or less, preferably 0.001 to 0.5 parts by weight. Both catalysts can be used alone or in combination.

Examples of the metal compound catalyst that can be used in the present invention include organic tin compounds, organic bismuth compounds, organic lead compounds and organic zinc compounds. Further, examples of amine-based catalysts having the action of promoting the resinification reaction include the following DBU-based compounds and imidazole-based compounds.

DBU (1,8-diaza-bicyclo [5.
4.0] undecene-7), and its carboxylic acid salt,
DBU compounds such as phenol salts. 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole,
1-benzyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-aminoethyl-2-methylimidazole, 1-isobutyl-
Imidazole compounds such as 2-methylimidazole, 1-cyanoethylaminoethyl-2-methylimidazole, 2-methylimidazole, 2-undecylimidazole and 2-heptadecylimidazole.

Further, an isocyanate group-merging catalyst for reacting isocyanate groups such as carboxylic acid metal salts and N, N, N-tris (dimethylaminopropyl) hexahydro-S-triazine is used according to the purpose. It is also possible to use together with a general tertiary amine catalyst which is a catalyst for promoting the foaming reaction, such as triethylenediamine or bis (2-dimethylaminoethyl) ether.

In addition to a foaming agent and a catalyst, a foam stabilizer for forming good cells is often used. Examples of the foam stabilizer include a silicone type foam stabilizer and a fluorine-containing compound type foam stabilizer. Other compounding agents that can be optionally used include, for example, fillers, stabilizers, colorants, flame retardants and the like.

Molding of the polyurethane foam with skin is preferably performed by a method of injecting the reactive mixture into a molding die using a high-pressure foaming machine (that is, a reaction injection molding method). The high-pressure foaming machine is preferably of a type in which two ordinary liquid components are mixed, usually one component is a component containing a polyisocyanate compound, and the other component is a mixture of all raw materials other than the polyisocyanate compound. It is an ingredient. In some cases, catalyst or defoaming agent (usually used by being dispersed or dissolved in some high molecular weight polyol)
It is also possible to form and inject a reactive mixture with a total of three components, each of which is a separate component.

Conventionally, it was considered essential to use R-11 as a foaming agent for polyurethane foam with skin.
However, according to the present invention, a good skin can be formed without using a CFC-based foaming agent such as R-11. Furthermore, good skin can be formed without the necessity of using a foaming agent composed of HCFC or other low boiling point organic compounds. That is, the use of polyoxyalkylene polyol having a low degree of unsaturation made it possible to form a skin by using only water or a thermal decomposition type foaming agent as a foaming agent. Furthermore, by using at least part of the low unsaturation polyoxyalkylene polyol obtained by using a cesium-based or rubidium-based catalyst, it is possible to significantly improve the fluidity without reducing the thickness of the skin layer. Found. It was also found that the improvement in fluidity can dramatically improve the molding defects (air voids, shrinks, etc.) of products having large and complicated shapes.

[0083]

EXAMPLES The present invention will now be described with reference to Examples (Examples 2, 4, 5, 7,
8) and comparative examples (Examples 1, 3, 6, 9, 10) will be specifically described, but the present invention is not limited thereto.

Raw Materials Used in Examples and Comparative Examples I. High molecular weight active hydrogen compound: Polyoxyalkylene polyols A1 to A9 were used. A1 to A9 are polyoxypropyleneoxyethylene polyols having an oxyethylene group only at the oxyalkylene chain end. Its molecular weight, number of functional groups, oxyethylene group content [EO group content] (wt%), degree of unsaturation (meq / g), hydroxyl value (mgKOH / g), polymerization catalyst and viscosity (cP, 25)
C) are shown in Table 1. DMC is zinc hexacyanocobaltate complex, CsOH is cesium hydroxide, and Cs
OCH ₃ is cesium methoxide and KOH is potassium hydroxide.

II. Chain extender: D1 and D2 shown in Table 2 were used. III. Catalyst: Amine-based catalysts F1 to F6 and metal compound-based catalysts G1 to G3 shown in Table 2 were used.

IV. Foam stabilizer: As the foam stabilizer H, a commercially available silicone foam stabilizer (trade name "SF-2962") was used. V. Foaming agent: Water was used as the foaming agent K1. VI. Polyisocyanate compound: As a polyisocyanate compound, a commercially available modified MDI (trade name "Coronate 1"
062 ") was used. The isocyanate group content of this was 27.0% by weight.

The above raw materials were used in the formulations shown in Tables 3-4. Numbers indicate parts by weight. USV represents the total degree of unsaturation of the polyoxyalkylene polyol mixture, the unit being me.
q / g.

Of these, the polyisocyanate compound was placed in one of the raw material tanks of the reaction injection molding apparatus (high pressure foaming machine), and the liquid temperature thereof was adjusted to 20 to 40 ° C. In addition, a mixture of a polyol compound, a chain extender, a catalyst and the like was placed in the other raw material tank of the reaction injection molding apparatus, and the liquid temperature thereof was 20 to 40.
Adjusted to ° C. Both have an isocyanate index of 1
It was mixed and injected at a ratio of 05. The isocyanate index means 100 times the equivalent of the isocyanate compound to 1 equivalent of all the active hydrogen compounds.

The injection conditions are as follows: injection pressure 150 kg / cm
² and the injection amount was 180 g / s. 300 mm for mold
A mold having internal dimensions of × 500 mm × 10 mm (t),
A mold having a plurality of partitions in the mold as shown in FIG. 1 was used for confirming moldability (air voids, degree of pinholes). The mold temperature was adjusted to 40 to 60 ° C.

The skin-forming state of the obtained foam with integral skin, that is, the molded product density (g / cm)
³ ), skin thickness (mm), and moldability (good: ⊚, generally good: ◯, somewhat poor: Δ, bad: ×) are shown in Tables 3 to 4.

[0091]

[Table 1]

[0092]

[Table 2]

[0093]

[Table 3]

[0094]

[Table 4]

[0095]

As is clear from the comparison between the examples and the comparative examples, in the foam with skin, it was very difficult to form a skin in foaming without using R-11 as a foaming agent. By using the system shown in the present invention, it is recognized that the moldability of the skin-formed polyurethane foam molded product produced without using R-11 is significantly improved. Further, since the fluidity of the raw material can be greatly improved, molding defects (air voids, shrinks, etc.) of products having large and complicated shapes are dramatically improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a mold having a plurality of partitions in the mold used in an embodiment of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area C08J 9/14 CFF C08J 9/14 CFF // (C08G 18/48 101: 00) C08L 75:04

Claims (7)

[Claims] 1. 80% by weight of a polyoxyalkylene polyol having a hydroxyl group number of 2 to 8 and a hydroxyl value of 3 to 60 (mgKOH / g) consisting of the following (a) 20 to 100% by weight and the following (b) 0 to 80% by weight. % Of the high molecular weight active hydrogen compound, chain extender, and polyisocyanate compound contained in the mold in the presence of a blowing agent containing water and / or an inert gas as a main component and a catalyst. A method for producing a polyurethane foam molded article with a skin, comprising the step of reacting with to produce a polyurethane foam molded article with a skin. (A): The number of hydroxyl groups is 2 to 8, and the hydroxyl value is 3 to 60
(MgKOH / g) and the total degree of unsaturation is 0.07 (m
eq / g) or less polyoxyalkylene polyol, or a polymer-dispersed polyol having the polyoxyalkylene polyol as a matrix, wherein at least a part of the polyoxyalkylene polyol is initiated by using a cesium-based or rubidium-based catalyst. A polyoxyalkylene polyol obtained by ring-opening polymerization of alkylene oxide in the presence of an agent. (B): A polyoxyalkylene polyol other than the above (a), or a polymer-dispersed polyol having the polyoxyalkylene polyol as a matrix. 2. The method according to claim 1, wherein the polyoxyalkylene polyol has a total degree of unsaturation of 0.07 (mgKOH / g) or less. 3. The proportion of the polyoxyalkylene polyol polymerized using a cesium-based or rubidium-based catalyst in the polyoxyalkylene polyol (a) is 30 to 30.
The manufacturing method according to claim 1, which is 100% by weight. 4. The method according to claim 1, wherein the foaming agent consists essentially of water. 5. The method according to claim 1, wherein the amount of the foaming agent used is 0.1 to 3 parts by weight based on 100 parts by weight of the high molecular weight active hydrogen compound. 6. The method according to claim 1, wherein the thickness of the obtained skin layer is 0.5 mm or more. 7. The method according to claim 1, wherein the polyoxyalkylene polyol (a) has a viscosity of 3000 cP or less at 25 ° C.