JPH05305629A - Manufacture of polyurethane foam molded aritcle - Google Patents

Abstract

PURPOSE:To improve the moldability of skinned polyurethane foam molded article without using R-11 by a method wherein specified polyoxyalkylene polyol, polyisocyanate compound and the like are reacted to one another in the presence of the predetermined foaming material and catalyst in molds. CONSTITUTION:Polyoxyalkylene polyol, the number of hydroxyl groups of which is 2-8, the hydroxyl value X and the total degree of unsaturation Y of which satisfy the following relationships: Y<=0.04 at 3<=X<=32.5, and Y<=0.9/(X-10) at 32.5<=X<=60, or polymer-dispersed polyol (a) having the above- mentioned polyoxyalkylene polyol as matrix is prepared. Further, polyoxyalkylene polyol or polymer-dispersed polyol (b) excluding (a) is also prepared. The desired molded article is obtained by reacting polymer active hydrogen, at least 80wt.% of which contains polyoxyalkylene polyol consisting of 20-100wt.% of the component (a) and 0-80wt.% of the component (b), chain extender and polyisocyanate compound to one another under the presence of the predetermined foaming material and catalyst in molds.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention 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 are suitable for automobile interior parts such as steering wheels, crash pads, headrests and armrests. It is used a lot.

A polyurethane foam molded article with integral skin is molded by forming an elastomer-like skin layer by suppressing foaming of the polyurethane raw material in the surface layer portion in contact with the inner wall of the mold when molding the polyurethane foam in a closed mold. To be done. Integral skin is usually
It means that the expansion ratio of the skin layer increases from the surface of the molded article 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 formation principle of the integral skin is considered as follows. That is, when foaming molding is performed 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 in the surface layer portion in contact with the inner wall of the molding die. It is considered that the CFC-based foaming agent cannot be vaporized due to the mold internal pressure, and the integral skin layer is formed.

Therefore, when producing polyurethane foam with integral skin, it is of course necessary to select a suitable polyol and isocyanate as raw materials, but the selection of the blowing agent is the most important. 30 ~
A foaming agent that does not vaporize near the inner wall of the mold at a temperature of 40 ° C., that is, has a boiling point not higher than the mold temperature is required. For that reason, only trichlorofluoromethane (R-11), which is a chlorofluorocarbon type foaming agent, has been conventionally 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 brittleness of the foam to be produced and economical disadvantage because the amount of the polyisocyanate compound used increases.
Furthermore, in the method for producing a polyurethane foam with integral skin, it was difficult for carbon dioxide, which has a low boiling point and is gaseous at room temperature, to form an integral skin.

[0008]

The present inventor generates a non-condensable gas such as carbon dioxide and ammonia at room temperature by water and thermal decomposition without using a chlorofluorocarbon type blowing agent such as R-11. Thermal decomposition type foaming agent,
Alternatively, they have found that a polyurethane foam molded article with a skin can be produced by using an inert gas such as air or nitrogen gas as a foaming agent.

The polyurethane foam molded article with a skin in the present invention is a molded article in which a non-foamed skin layer made of the same polyurethane material as the polyurethane foam is integrally formed at the same time when the polyurethane foam is formed. 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. The following (a) 20 to 100% by weight and the following (b)
Number of hydroxyl groups 2 to 8, consisting of 0 to 80% by weight, hydroxyl value 3 to
A high molecular weight active hydrogen compound containing at least 80% by weight of 60 (mgKOH / g) polyoxyalkylene polyol, a chain extender, and a polyisocyanate compound,

Molding mold which is closed in the presence of water, a pyrolytic foaming agent that thermally decomposes to generate a gas, a foaming agent containing at least one selected from an inert gas, and a catalyst. A method for producing a polyurethane foam molded article with a skin, characterized by producing a polyurethane foam molded article with a skin by reacting inside.

(A): Number of hydroxyl groups 2 to 8, hydroxyl value X (m
gKOH / g) is 3 ≦ X ≦ 60, and 3 ≦ X ≦ 32.
When 5, the total degree of unsaturation Y (meq / g) is Y ≦ 0.04, and when 32.5 ≦ X ≦ 60, X and Y are polyoxyalkylene polyols having the relationship of the following formula (1),
Alternatively, a polymer-dispersed polyol having the polyoxyalkylene polyol as a matrix. Y ≦ 0.9 / (X-10) (1)

(B): A polyoxyalkylene polyol other than the above (a), or a polymer-dispersed polyol having the polyoxyalkylene polyol as a matrix.

It is known that a method for producing a highly elastic polyurethane foam by using a polyoxyalkylene polyol having a low total unsaturation such as the above (a) and a method for producing a polyurethane elastomer molded article by reaction injection molding. For example, Japanese Patent Publication No. 61-
No. 31130, Japanese Patent Publication No. 61-45730, Japanese Patent Laid-Open No. 3-14812.

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, the temperature rises sharply in the latter half of the polyurethane foam formation reaction and the temperature difference between the mold surface and the foam interior becomes large. Due to the phenomenon that is remarkable when a catalyst and an organometallic catalyst are used together, the resin layer precedes the formation of a skin layer on the mold surface, and then foaming and resinification occur inside to form a foam layer. Expected to be done. In addition, 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. It is conceivable that the resin strength is increased by increasing the number of cross-linking points and the molecular weight and thereby suppressing the foaming in the skin layer once formed.

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

The essential component (a) in the present invention is
It is a polyoxyalkyleneylene polyol having a hydroxyl value of 3 to 60 (mgKOH / g) and a low degree of unsaturation.
The degree of unsaturation in (a) must be 0.04 (meq / g) or less. In addition, those having a relatively high hydroxyl value are required to have a lower degree of unsaturation. That is,
Hydroxyl value X (mgKOH / g) and degree of unsaturation Y (meq /
With respect to g), when X is 32.5 or less, Y is 0.04 or less, and when X is 32.5 or more, the relationship represented by the formula (1) (that is, Y is [0.9 / (X-10)] or less).

The more preferred hydroxyl value of (a) is 3-40.
(MgKOH / g), the degree of unsaturation is 0.03 (meq /
g) Below. More preferred (a) is a hydroxyl value of 3
~ 35 (mgKOH / g), degree of unsaturation 0.03 (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. In addition, it is needless to say that (a) may be a mixture of two or more polyxyalkylene polyols, and 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 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 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 at least about 3% by weight, preferably at least 5% by weight, of oxyethylene groups at the terminal is preferable. Preferred (a) is oxypropylene group content 75% by weight or more, oxyethylene group content 3 ~
20% by weight of a polyoxyalkylene polyol mainly containing oxypropylene groups, that is, a polyoxypropylene-based polyol.

(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 a polyol, and is obtained, for example, by polymerizing a vinyl monomer such as acrylonitrile or styrene in the polyol.

Generally, a polyoxyalkylene polyol used as a raw material for polyurethane is produced by ring-opening addition polymerization of an alkylene oxide such as propylene oxide with an initiator such as a polyhydric alcohol using an alkali catalyst such as an alkali metal hydroxide. ing. However, this production method using an alkali catalyst tends to cause a reaction in which monool having an unsaturated group is by-produced.

It is not impossible to produce a polyoxyalkylene polyol having a low unsaturation and a low hydroxyl value using an alkali catalyst (it is considered possible if mild reaction conditions are used), but preferably other Polyoxyalkylene polyols produced using a catalyst are preferred.

Other catalysts include, for example, metalloporphyrin (see JP-A-61-197631) and LiP.
F ₆ (see Japanese Patent Laid-Open No. 60-197726), a complex metal cyanide complex (see Japanese Patent Publication No. 59-15336 and US Pat. No. 3,929,505), a metal and a chelating agent having three or more coordination sites. Complex (JP-A-60-1977)
No. 26). In particular, it is preferable to use a double metal cyanide complex.

(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 range of the above (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 a polyoxyalkylene polyol is produced using a usual alkali catalyst. This (b)
The total degree of unsaturation of the polyoxyalkylene polyol 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 (b) polyoxyalkylene polyol 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,
Examples include polyoxyalkylene polyols not containing an oxyethylene group, polyoxyalkylene polyols mainly containing an oxyalkylene group having 3 or more carbon atoms other than an oxypropylene group. 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 can be 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.

The polyhydric initiator used when producing the above polyoxyalkylene polyol includes polyhydric alcohols, polyhydric phenols, polyamines and alkanolamines. For example, ethylene glycol, diethylene glycol, propylene glycol,
Dipropylene glycol, neopentyl glycol,
1,4-butanediol, 1,6-hexanediol,
Examples thereof include glycerin, trimethylolpropane, pentaerythritol, diglycerin, dextrose, sucrose, bisphenol A, ethylenediamine, and polyoxyalkylene polyol having a lower molecular weight than the target 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. In particular,
In order to carry out a 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 an alkylene oxide having 3 or more carbon atoms such as 1,2-propylene oxide to a polyvalent initiator and then adding ethylene oxide. The oxyethylene group may also be present inside the polyoxyalkylene chain. When an oxyethylene group is present at the end of a polyoxyalkylene chain for the purpose of improving reactivity, the content of the oxyethylene group is usually required to be at least 3% by weight, particularly at least 5% by weight.

The higher the content of oxyethylene groups in the polyoxyalkylene polyol, the more hydrophilic the resulting polyurethane foam with skin. For molded products used outdoors such as air spoilers for automobiles,
If the hydrophilicity is too high, the water absorption will be high and the dimensional stability will be reduced, 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 in the terminal portion of the molecular chain. When the polyurethane foam with skin is not required to have low hydrophilicity, the upper limit of the oxyethylene group content is not limited to this.

As described above, a 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 this matrix, and examples of the polymer include addition polymerization type polymers and condensation polymerization type polymers.

The polymer fine particles in the polymer-dispersed polyol are acrylonitrile, styrene, methacrylate,
It is composed of addition polymerization type polymers such as acrylate and other homopolymers and copolymers of vinyl monomers, and condensation polymerization type polymers such as polyester, polyurea, polyurethane and melamine resin. 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, it is preferable that the total hydroxyl value of the polymer-dispersed polyol having the polyoxyalkylene polyol (a) as a matrix is 60 or less, particularly 3 to 35.

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

The polyoxyalkylene polyol in the present invention comprises the above (a) or (a) and (b). The combination is (a) 2 for the sum of (a) and (b).
0 to 100% by weight and (b) 0 to 80% by weight. More preferably, (a) 50-100 wt% and (b) 0-
It consists of 50% by weight. More preferably, (a) 70-
100% by weight and (b) 0 to 30% by weight. The average hydroxyl value of the mixture of both [represented by (a + b) below] needs to be 3 to 60 (mgKOH / g). More preferable average hydroxyl value of (a + b) is 3 to 40 (mg
KOH / g). 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.

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 the above (a + b) in an amount of 80% by weight or more. Other high molecular weight active hydrogen compounds may be included, but the amount is at most 20% by weight.

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 group-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 at least one primary amino group or secondary amino group 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 molecular weight of 600
There is a compound obtained by converting a part or all of the hydroxyl groups of the above polyoxyalkylene polyol into a primary amino group, a secondary amino group, or an organic group having such an amino group. 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 the 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, the chain extender means a hydroxyl group, 1
Molecular weight 60 having two or more active hydrogen-containing groups capable of reacting with a primary amino group, a secondary amino group and other isocyanate groups
Refers to compounds less than 0. In particular, hydroxyl group, primary amino group,
Compounds having two or more functional groups selected from secondary amino groups and having a molecular weight of 400 or less are preferable. Two or more chain extenders may be used in combination. 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 chain extender having a hydroxyl group is
It preferably has 2 to 4 hydroxyl groups. This polyol chain extender includes typical chain extenders such as ethylene glycol and 1,4-butanediol. In addition, there are other polyhydric alcohols and polyols such as low molecular weight polyoxyalkylene polyols obtained by adding alkylene oxides to polyhydric alcohols and polyols having a tertiary amino group.

Specific examples of the polyol chain extender include, but are not limited to, the compounds exemplified below. Preferably 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 be used as a chain extender. Examples of such a chain extender include monoethanolamine, diethanolamine, monoisopropanolamine and the like.

Examples of the amine chain extender 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. The aromatic diamine is preferably 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 the aromatic nucleus to which an amino group is bound. Particularly preferred are diaminobenzene derivatives. The above-mentioned substituents other than the electron-withdrawing group are preferably bonded to 2 to 4 aromatic nuclei to which an amino group is bonded, and particularly, at least one ortho position relative to the binding site of the amino group, and preferably to 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. Of course, the electron withdrawing group and the other substituent may be bonded to one aromatic nucleus. The alkyl group, the alkoxy group, and the alkylthio group preferably have 4 or less carbon atoms, and the cycloalkyl group is preferably the 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. Examples of the alicyclic polyamine include cycloalkane having two or more amino groups and / or aminoalkyl groups.

Specific examples of the amine 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-dimethylthio-2,4- (or 2,6) -diaminobenzene, 1-trifluoromethyl-3,5-diaminobenzene, 1-trifluoromethyl-4- Chlor-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 of 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 (IPDI), hexamethylene diisocyanate (HMDI). ) And other polyisocyanates and their prepolymer-type modified products, nurate modified products, urea modified products, and carbodiimide modified products.

The preferred polyisocyanate compound is M
It is a mixture of a DI modified product, 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 equivalent or more based on the total equivalents of the high molecular weight active hydrogen compound and the chain extender. When the isocyanate group-multiplying catalyst is not used, the upper limit is usually 1.5 times equivalent, preferably 1.3 times equivalent. The preferred amount of the polyisocyanate compound used in the present invention is 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 water,
A thermal decomposition type foaming agent that thermally decomposes to generate gas, and a foaming agent containing at least one selected from an inert gas as a main component. Water reacts with the polyisocyanate compound to generate carbon dioxide. Gases generated by the thermal decomposition of the pyrolytic foaming agent include carbon dioxide, ammonia, nitrogen gas and the like. The inert gas includes air and nitrogen gas.
Water, a pyrolytic foaming agent, 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 thermal decomposition type foaming agent in the present invention includes:
Compounds that thermally decompose to release carbon dioxide or ammonia are preferred. This thermal decomposition type foaming agent thermally decomposes in a high temperature atmosphere due to the reaction heat at the time of forming a polyurethane foam to generate a gas. The thermal decomposition temperature is preferably 40 to 100 ° C, particularly preferably 50 to 80 ° C. Specific compounds include, for example, ammonium carbonate, ammonium hydrogencarbonate, and ammonium carbamate, which decompose at about 60 ° C. to release carbon dioxide and ammonia.

As a foaming agent for producing a foam of a general thermoplastic resin, a foaming agent which generates ammonia is difficult to use due to environmental problems such as odor. However, in the present invention, the generated ammonia does not react with the polyisocyanate compound promptly and is not released to the outside of the reaction system, so such a problem does not occur.

The thermal decomposition type foaming agent is preferably used by adding it to a high molecular weight active hydrogen compound or a component containing the same. In particular, it is preferable that the fine powder is added and dispersed, or that the fine powder is dissolved in a solvent such as monoalcohol or polyhydric alcohol or water before the solution is added.

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 foaming agents that can be used in combination as described below, 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,
Examples include methylene chloride, butane, pentane, isopentane, hexane, acetone and cellosolve. The amount of the foaming agent that can be used in combination is not particularly limited, but when used in combination with water, the high molecular weight active hydrogen compound 100 is used.
Up to 12 parts by weight, especially up to 8 parts by weight, are suitable with respect to parts by weight.

In the present invention, it is not essential to use a foaming agent which can be used in combination as described above, particularly a low-boiling organic compound-based foaming agent, and for example, to produce a good polyurethane foam with a skin using only water as a foaming agent. You can

When reacting the polyol 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. A metal compound catalyst or a certain amine catalyst is effective as a catalyst for promoting the resinification reaction. Amine-based catalysts that are mainly used in the production of polyurethane foams 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-forming reaction is used. Of course, a relatively small amount of a catalyst that promotes the foaming reaction can be used together with such an amine catalyst or a metal compound catalyst.

When an amine-based catalyst having an action of promoting the resinification reaction is used, the amount thereof is preferably 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, and 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 carboxylate salts,
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 the foaming agent and the 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 optional additives include fillers, stabilizers, colorants, flame retardants and the like.

Molding of the polyurethane foam with skin is preferably carried out by a method of injecting the reactive mixture into a mold 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 of the components is a component containing a polyisocyanate compound, and the other component contains 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 dispersing to dissolving 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, it is possible to form a good skin without using a CFC-based foaming agent such as R-11. Furthermore, it is possible to form a good skin without the necessity of using a foaming agent composed of HCFC or other low boiling point organic compounds. That is, by using a polyoxyalkylene polyol having a low degree of unsaturation, it is possible to form a skin by using only water or a heat decomposition type foaming agent as a foaming agent.

[0071]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Raw Materials Used in Examples and Comparative Examples I. High molecular weight active hydrogen compound Polyoxyalkylene polyols A1 to A6 and amino group-containing polyoxyalkylene compound B were used.
A1 to A6 are polyoxypropyleneoxyethylene polyols having an oxyethylene group only at the oxyalkylene chain ends. Its molecular weight, number of functional groups, oxyethylene group content [EO group content] (wt%), degree of unsaturation (m
Table 1 shows the eq / g) and the hydroxyl value (mgKOH / g). B is a trade name "Jeffamine T5000" which is considered to be polyoxypropylenetriamine obtained by converting the hydroxyl group of polyoxypropylenetriol having a molecular weight of 5000 into a primary amino group.

II. Chain extender D1 to D3 shown in Table 2 were used. III. Catalysts Amine-based catalysts F1 to F6 and metal compound-based catalysts G1 to G5 shown in Table 2 were used. Of these, F1 and F6 are amine-based catalysts that promote the usual foaming reaction.

IV. As a foam stabilizer H, a commercially available silicone foam stabilizer (trade name "S
F-2962 ") was used. V. Blowing agents Blowing agents K1 to K5 shown in Table 2 were used. VI. Polyisocyanate Compound As the polyisocyanate compound N, a commercially available modified MDI was used.
(Product name “Coronate 1062”) was used. The isocyanate group content of this product is 27.0% by weight.

The above raw materials were used in the formulations shown in Tables 3 to 5 (numbers are parts by weight). Among these, the polyisocyanate compound was put into one raw material tank of the reaction injection molding apparatus (high pressure foaming machine), and the liquid temperature thereof was adjusted to 20 to 40 ° C. Further, 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 adjusted to 20 to 40 ° C.

Both have an isocyanate index of 10
It was mixed and injected at a ratio of 5. Isocyanate
Dex is the equivalent of 1 equivalent of all active hydrogen compounds.
It means 100 times the equivalent of the cyanate compound. Injection condition
Is an injection pressure of 150 kg / cm ² , Injection amount 300g / s
And 300 mm x 500 mm x 10 mm for the mold
A mold having an inner dimension of (t) is used, and the mold temperature is 40 to
The temperature was adjusted to 60 ° C.

The skin-forming state of the obtained foam with integral skin, that is, the molded product density (g / cm
³ ) and skin thickness (mm) are shown in each table. Example 10 is a comparative example.

[0078]

[Table 1]

[0079]

[Table 2]

[0080]

[Table 3]

[0081]

[Table 4]

[0082]

[Table 5]

[0083]

As is clear from the comparison between the example and the comparative example, it was very difficult to form a skin in the foam with skin in the foaming without using R-11 as the foaming agent. By using the system shown in the present invention, it is recognized that the moldability of the polyurethane foam molded article with skin produced without using R-11 is significantly improved.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display area // (C08G 18/66 101: 00) C08L 75:04

Claims (10)

[Claims] 1. A polyoxyalkylene polyol having a hydroxyl number of 2 to 8 and a hydroxyl value of 3 to 60 (mgKOH / g) consisting of 20 to 100% by weight of the following (a) and 0 to 80% by weight of the following (b). At least one selected from water, a thermal decomposition type foaming agent that thermally decomposes a high molecular weight active hydrogen compound, a chain extender, and a polyisocyanate compound that are contained by weight to generate a gas, and an inert gas. A method for producing a polyurethane foam molded article with skin, which comprises reacting in a closed mold in the presence of a foaming agent and a catalyst to produce a polyurethane foam molded article with skin. (A): Number of hydroxyl groups 2 to 8, hydroxyl value X (mgKOH /
g) is 3 ≦ X ≦ 60, 3 ≦ X ≦ 32.5, the total degree of unsaturation Y (meq / g) is Y ≦ 0.04, and 32.5 ≦ X ≦ 60 is X. , Y is a polyoxyalkylene polyol having the relationship of the following formula (1), or a polymer-dispersed polyol having the polyoxyalkylene polyol as a matrix. Y ≦ 0.9 / (X-10) (1) (b): A polyoxyalkylene polyol other than the above (a), or a polymer-dispersed polyol having the polyoxyalkylene polyol as a matrix. 2. A polyoxyalkylene polyol is
The method according to claim 1, comprising (a) 50 to 100% by weight and (b) 0 to 50% by weight. 3. The polyoxyalkylene polyol of (a) has a hydroxyl group number of 2 to 8 and a hydroxyl value of 3 to 40 (mgKOH /
The production method according to claim 1, which is a polyoxyalkylene polyol having a total degree of unsaturation of 0.03 (meq / g) or less. 4. The method according to claim 3, wherein the polyoxyalkylene polyol (a) is a polyoxypropylene-based polyol having an oxypropylene group content of 75% by weight or more and an oxyethylene group content of 0 to 20% by weight. . 5. The polyoxyalkylene polyol of (b) has a hydroxyl group number of 2 to 8 and a hydroxyl value of 20 to 110 (mgKO).
H / g) is a polyoxyalkylene polyol. 6. The method according to claim 1, wherein the foaming agent consists essentially of water. 7. The method according to claim 1, wherein the pyrolytic foaming agent is a pyrolytic foaming agent that thermally decomposes to generate at least one selected from carbon dioxide and ammonia. 8. 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. 9. The method according to claim 1, wherein the thickness of the obtained skin layer is 0.5 mm or more. 10. A polyurethane foam molded article with a skin is produced by reaction injection molding using two components, a component containing a high molecular weight active hydrogen compound and a chain extender and a component containing a polyisocyanate compound. Manufacturing method.