JP3260195B2 - Method for producing polyurethane foam molded article - Google Patents

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 having a skin .

[0002]

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

[0003] A polyurethane foam molded product with an integral skin is formed by forming an elastomeric skin layer by suppressing foaming of a polyurethane raw material in a surface portion in contact with an inner wall of a polyurethane foam when the polyurethane foam is molded in a closed mold. Molded. Integral skin usually refers to a skin layer in which the expansion ratio of the skin layer increases (that is, the density decreases) from the surface of the molded article toward the inside, and in many cases, the boundary between the skin layer and the foam layer is clear. Is not something.

The principle of forming the integral skin is considered as follows. In other words, when foaming is performed in a mold using a raw material containing a relatively high-boiling fluorocarbon blowing agent as a foaming agent, reaction heat is deprived to the mold at the surface layer in contact with the mold inner wall, and the molding is performed at the same time. It is considered that the integral skin layer is formed without the CFC-based blowing agent being vaporized due to the internal pressure of the mold.

[0005] Therefore, when producing a polyurethane foam with integral skin, it is of course necessary to select a polyol and an isocyanate suitable as raw materials, but the selection of a 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 chlorofluorocarbon-based blowing agent, trichlorofluoromethane (R-11), has conventionally been used.

[0006]

However, chlorofluorocarbon-based blowing agents such as R-11 may destroy the protective ozone layer on the earth by the ozone destruction chain reaction. I have.

Water that reacts with a polyisocyanate compound to release carbon dioxide has been used as a substitute for a chlorofluorocarbon-based blowing agent. However, embrittle the foam produced, the amount is economically disadvantageous to increase the polyisocyanate compound, there are drawbacks such. Further, in the method for producing a polyurethane foam with an integral skin, it was difficult to form an integral skin with carbon dioxide having a low boiling point and gas at room temperature.

[0008]

The inventor of the present invention generates a non-condensable gas such as carbon dioxide and ammonia at room temperature without using a chlorofluorocarbon-based blowing agent such as R-11 and by water or thermal decomposition. thermal decomposition type foaming agent or
Others have found that by using an inert gas such as air or nitrogen gas as a foaming agent, kill <br/> the skinned polyurethane foam molded article manufacturing.

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 molding of the polyurethane foam. Say. The skin in the present invention means not only an integral skin but also a skin whose boundary with the foam layer is relatively clear as compared with the integral skin.

The present invention is the following invention which has solved the above-mentioned problems. The following (a) 20 to 100% by weight and the following (b)
0 to 80% by weight of hydroxyl group number 2 to 8, hydroxyl value 3 to 3
A high molecular weight active hydrogen compound containing at least 80% by weight of 60 (mg KOH / g) polyoxyalkylene polyol, a chain extender, and a polyisocyanate compound;

[0011] Water, pyrolyzed foaming agent and the presence of a catalyst composed mainly of at least one selected from the thermally decomposable foaming agent Contact and inert gas to generate gas, sealed mold in And producing a polyurethane foam molded article with a skin by reacting in step (a).

(A): 2 to 8 hydroxyl groups, 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 represented by 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.

It is known that a method of producing a highly elastic polyurethane foam by using a polyoxyalkylene polyol having a low total unsaturation such as the above (a) or a method of producing a polyurethane elastomer molded article by reaction injection molding. For example, Japanese Patent Publication according to the present applicant, filed 61-3
No. 1130, JP-B-61-45730, and JP-A-3-14812.

In the present invention, if a polyoxyalkylene polyol having a low total unsaturation is used, the reason why a skin is formed even by foaming with a non-condensable gas such as carbon dioxide is not clear. When the degree of unsaturation of the raw material polyoxyalkylene polyol decreases, a sharp temperature rise occurs in the second half of the polyurethane foam formation reaction, and the temperature difference between the mold surface and the inside of the foam increases. it is remarkable when the combination of catalyst and organic metal catalyst, a cathodic et al., the skin layer is formed by resin of the mold surface is preceded, subsequently occur foaming and resinification inside foam layer formed Expected. Further, when the degree of unsaturation of the polyoxyalkylene polyol decreases, the amount of the unsaturated monool contained therein decreases, that is, the true average number of functional groups increases as compared with those having a high degree of unsaturation. It is also conceivable that the resin strength is increased due to an increase in the number of cross-linking points and the molecular weight, thereby suppressing foaming in the skin layer once formed.

Generally speaking, the lower the hydroxyl value of a polyoxyalkylene polyol (ie, the higher the molecular weight), the higher the degree of unsaturation. The reason is that the lower the hydroxyl value, the larger the amount of the oxyalkylene group having 3 or more carbon atoms, particularly the oxypropylene group, which is the main oxyalkylene group of the polyoxyalkylene polyol. This is because the reaction amount of the alkylene oxide increases, and accordingly, the side reaction of the alkylene oxide (reaction generating an unsaturated group) also increases.

In the present invention, the essential component (a) is
Polyoxyalkylene 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 need to have a further lower degree of unsaturation. That is,
The hydroxyl value X (mgKOH / g) and the degree of unsaturation Y (meq /
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 above formula (1) (that is, Y is [0.9 / (X-10)].

The more preferred hydroxyl value of (a) is from 3 to 40.
(MgKOH / g), and the degree of unsaturation is 0.03 (meq / g
g) below. More preferred (a) is a hydroxyl value of 3
~ 35 (mgKOH / g), 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. Incidentally, are (a) is also a mixture of two or more poly alkoxy polyalkylene polyols rather good <br/>, as the degree of unsaturation, hydroxyl value, and hydroxyl number ranges of the average of the case .

(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, has no side reaction to generate an unsaturated group in its formation reaction (addition reaction of ethylene oxide), a polyoxyalkylene polyol having a high ratio of oxyethylene groups is originally used. Low degree of unsaturation. However, a polyurethane foam molded article with a skin obtained using a polyoxyalkylene polyol having a high ratio 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 an oxyalkylene group having 3 or more carbon atoms, especially an oxypropylene group, is 75%.
% By weight or more of polyoxyalkylene polyol is preferred. Further, 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 3 % by weight , preferably at least 5% by weight of oxyethylene group at the terminal is preferable. Preferred (a) is that the oxypropylene group content is 75% by weight or more, and the oxyethylene group content is 3 to 20%.
% By weight of a polyoxyalkylene polyol mainly containing oxypropylene groups, that is, a polyoxypropylene-based polyol.

(A) may be a polymer-dispersed polyol having the above-mentioned polyoxyalkylene polyol as a matrix, or a mixture of the polymer-dispersed polyol and the 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 by, for example, polymerizing a vinyl monomer such as acrylonitrile or styrene in the polyol.

[0022] Generally, the polyoxyalkylene polyol used as a raw material for polyurethane by ring-opening addition polymerization of alkylene oxides such as propylene oxide to an initiator such as a polyhydric alcohol using an alkali catalyst such as an alkali metal hydroxide produced Have been. However, in the production method using an alkali catalyst, a reaction in which a monol having an unsaturated group is by-produced easily occurs.

Although it is not impossible to produce a polyoxyalkylene polyol having a low degree of unsaturation and a low hydroxyl value by using an alkali catalyst (in particular, it is considered possible to use mild reaction conditions) , other catalysts may be used. Polyoxyalkylene polyols prepared using the same are preferred.

[0024] Other catalysts, (see JP-A-61-197631) metalloporphyrins In example embodiment, LiPF
₆ (see JP-A-60-197726), a complex metal cyanide complex (see Japanese Patent Publication No. 59-15336, and US Pat. No. 3,929,505), and a metal and a chelating agent having a tridentate or higher coordination. Complex (JP-A-60-19772)
No. 6). In particular, it is good preferable to use a composite metal cyanide complex.

(B) is a polyoxyalkylene polyol other than the polyoxyalkylene polyol (a) and a polymer-dispersed polyol having the polyoxyalkylene polyol as a matrix. The polyol has 2 to 8 hydroxyl groups and a hydroxyl value of 20 to 11
0 is preferred. The total degree of unsaturation exceeds the range of the above (a) at a hydroxyl value of 60 or less.
If it exceeds 0, it is 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 number 3 or more oxyalkylene group having a carbon is preferably at least 55 wt%. When it contains an oxyethylene group, the oxyethylene group content is preferably 40% by weight or less, and at least a part of the oxyethylene group content is preferably present at the end of the polyoxyalkylene chain. More preferably, the polyoxyalkylene polyol (b) has an oxypropylene group content of 55% by weight or more,
It is a polyoxypropylene-based polyol having an oxyethylene group content of 3 to 40% by weight.

As the polyoxyalkylene polyol (b), various polyoxyalkylene polyols other than those described above can be used. For example, a higher hydroxyl value polyoxyalkylene polyol, a higher oxyethylene group content polyoxyalkylene polyol,
Examples thereof include polyoxyalkylene polyols containing no oxyethylene group and polyoxyalkylene polyols mainly containing an oxyalkylene group having 3 or more carbon atoms other than the oxypropylene group. Even if these polyoxyalkylene polyols are used, the polyoxypropylene-based polyol (oxypropylene group content 55
% Of oxyethylene group content of 3 to 40% by weight.
(Lioxypropylene-based polyol) . Usually, these polyols are preferably used in combination with the above-mentioned 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 polyoxyalkylene polyols (a) and (b) are generally produced as follows.
In other words, obtained by adding at least one alkylene oxide in the presence polyvalent initiator 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,
It is preferable to use 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.

The polyhydric initiator used for producing the above polyoxyalkylene polyol includes 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,
Examples include glycerin, trimethylolpropane, pentaerythritol, diglycerin, dextrose, sucrose, bisphenol A, ethylenediamine, and polyoxyalkylene polyols having a lower molecular weight than those obtained by adding an alkylene oxide thereto. These initiators may be used alone .
Two or more kinds may be used in combination. Particularly preferred polyhydric initiator is a polyhydric alcohol.

The hydroxyl group in the polyoxyalkylene polyol preferably contains a highly reactive hydroxyl group, that is, a primary hydroxyl group in a high ratio. In particular,
In order to perform a reaction injection molding method that requires the use of a raw material having high reactivity, an oxyethylene group usually needs to be present at the terminal of the molecular chain of the polyoxyalkylene polyol.

[0032] Such polyoxyalkylene polyols are obtained by adding ethylene oxide after adding multivalent number of 3 or more alkylene oxides of carbon, such as initiator in 1,2-propylene oxide. Oxyethylene groups may also be present within the polyoxyalkylene chain. When an oxyethylene group is present at the end of the polyoxyalkylene chain for the purpose of improving the 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 is high, hydrophilicity of the resulting skinned polyurethane foam becomes high. In the case of a molded product used outdoors such as an air spoiler for automobiles, if the hydrophilicity is too high, the water absorption becomes high, and the dimensional stability is unfavorably reduced. Therefore, the content of oxyethylene groups in all polyoxyalkylene polyols is preferably 35% by weight or less, particularly preferably 25% by weight or less. Further, in that case, it is preferable that most of the oxyethylene groups be present at the terminal of the molecular chain. In the case where 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, as (a) and (b) in the present invention, a polymer-dispersed polyol having the polyoxyalkylene polyol as a matrix can be used. Further, a polymer-dispersed polyol produced using a mixture of the polyoxyalkylene polyols (a) and (b) as a matrix may be used. 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 polymer fine particles in the polymer-dispersed polyol include acrylonitrile, styrene, methacrylate,
It is composed of an addition polymer type polymer such as homopolymer or copolymer of acrylate or other vinyl monomer, or a polycondensation type polymer such as polyester, polyurea, polyurethane or 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 polyol in the matrix. Therefore, the total hydroxyl value of the polymer-dispersed polyol having the polyoxyalkylene polyol (a) as a matrix is preferably 60 or less, particularly preferably 3 to 35.

The content of the fine polymer particles in the mixture of the polymer-dispersed polyol or it and the polyoxyalkylene polyol is usually 60 wt% or less, especially 40 wt% 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, less than 20% by weight is sufficiently effective. The presence of the polymer particles in the polyoxyalkylene polyol is not a mandatory, if it is present form of hardness, air permeability, it is effective in improving the other physical properties.

The polyoxyalkylene polyol in the present invention comprises the above (a) or (a) and (b). The combination is (a) 2 with respect to the sum of (a) and (b).
0 to 100% by weight and (b) 0 to 80% by weight. More preferably, (a) 50 to 100% by weight and (b) 0 to 100% by weight.
Consists of 50% by weight. More preferably, (a) 70 to
100% by weight and (b) 0 to 30% by weight. Rights Hitoshimizu Sanmotoka of [represented by the following (a + b)] a mixture of both the 3
It must be 60 (mgKOH / g). More preferably (a + b) of the flat Hitoshimizu Sanmotoka is 3~40 (mgKOH /
g). Further, the above manner (a + b) flat Hitoshio key <br/> Shiechiren group content of 35 wt% or less, especially 25 wt%
The following is preferred.

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 contained, 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 as an optional component, but its use is not essential. However, for the purpose of improving the physical properties of the skin with a polyurethane foam, or
Others can be used for other purposes. For example,
It may be preferable to use a high hydrophobic high molecular weight polyol such as hydroxyl group-containing polybutadiene in order to reduce the hydrophilicity of the polyurethane foam with skin.

[0040] Examples of such high molecular weight polyols,
The average molecular weight per hydroxyl group is 400 or more, particularly 800 or more, and the number of average hydroxyl groups per molecule is 1.6 to 4
Is preferred. The average molecular weight per hydroxyl group is preferably 10,000 or less. As such high molecular weight polyols, for example, a hydroxyl group-containing hydroxyl group-containing hydrocarbon polymers such as Poributashien, there are etc. polyester poly <br/> O Le.

[0041] In yet another high molecular weight active hydrogen compound, a primary amino group or may be used in combination of high molecular weight active hydrogen compound having one or more secondary amino groups. The 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, and has a molecular weight of 600. The above amino group-containing polyoxyalkylene compounds are preferred. Examples of such amino group-containing polyoxyalkylene compounds, e.g., a portion of the molecular weight of 600 or more hydroxyl groups in the polyoxyalkylene polyol or
Others are compounds obtained by converting all primary amino group, secondary amino group or an organic group having such amino group. In particular, an amino group-containing polyoxyalkylene compound obtained by converting a part or all of the hydroxyl groups of a polyoxypropylene polyol to a primary amino group is preferable. Further, a compound obtained by reacting a polyoxyalkylene polyol with an excess equivalent amount of a polyisocyanate compound to obtain an amino group by hydrolyzing an isocyanate group of a prepolymer having an isocyanate group at a terminal and converting 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 to 8. The molecular weight per functional group is preferably 10,000 or less.

In the present invention, the chain extender includes a hydroxyl group,
Molecular weight 600 having at least two active hydrogen-containing groups capable of reacting with isocyanate groups , such as secondary amino groups and secondary amino groups
Less than compounds. In particular, it has two or more functional groups selected from a hydroxyl group, a primary amino group, and a secondary amino group,
And molecular weight 400 The following compounds are preferred. Two or more chain extenders may be used in combination. The amount of the chain extender to be used is suitably 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-based chain extender having a hydroxyl group includes
It preferably has 2 to 4 hydroxyl groups. The polyol-based chain extenders include typical chain extenders such as ethylene glycol and 1,4-butanediol. In addition, there are polyols such as other polyhydric alcohols and low molecular weight polyoxyalkylene polyols obtained by adding alkylene oxide to the polyhydric alcohols, and polyols having a tertiary amino group.

Specific examples of the polyol-based chain extender include the following compounds, but are not limited thereto. 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- alkyl diethanolamine, bisphenol A -
Alkylene oxide adduct.

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

Examples of the amine-based 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. 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 on an aromatic nucleus to which an amino group is bonded is preferable. Particularly, a diaminobenzene derivative is preferable. The substituents other than the electron-withdrawing group are preferably bonded to an aromatic nucleus to which an amino group is bonded in an amount of 2 to 4, especially at least one, and preferably all, at the ortho position to the amino group bonding site. It is preferred that they are bonded.

The electron withdrawing group is preferably 1 or bond two to an aromatic nucleus where amino groups are attached. Electron withdrawing groups and other substituents 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 a cyclohexyl group. Examples of the electron-withdrawing group include a halogen atom, a trihalomethyl group, a nitro group, a cyano group,
Preferably an alkoxycarbonyl group, especially a chlorine atom, trifluoromethyl group or nitro group is preferred.

The part of the aliphatic polyamines as diaminoalkane or a polyalkylene polyamine having 6 or less carbon atoms, the low molecular weight polyoxyalkylene polyol hydroxyl Also
There are such polyamines obtained by converting the whole to an amino group. Further, 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, or an aromatic compound having the above-described substituent is used. You can also. As the alicyclic polyamine, there is a cycloalkane having two or more amino groups and / or aminoalkyl groups.

Specific examples of the amine-based chain extender are shown below, but are not limited thereto. Particularly preferred are diethyl toluene diamine [i.e., 1-methyl-3,5-diethyl-2,4 (or 2,6) - one or a mixture of diaminobenzene, dimethylthiotoluenediamine, monochloro Diaminobenzene derivatives such as diaminobenzene and 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-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 of polyurethane is a polyisocyanate compound. As the polyisocyanate compound, an aromatic having two or more isocyanate groups, alicyclic, Moshiku the aliphatic polyisocyanate, these two
There are modified polyisocyanate obtained by modifying or more mixtures or their. Specifically, for example, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymethylene polyphenyl isocyanate (commonly called crude MDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HMDI) And polyisocyanates thereof, and their modified prepolymers, nurate, urea and carbodiimide.

Preferred polyisocyanate compounds include M
A modified DI, crude MDI, or a mixture of aromatic polyisocyanates containing one of them as a main component.
The amount of the polyisocyanate compound to be used is usually 0.8 times or more equivalent to the total equivalent of the high molecular weight active hydrogen compound and the chain extender. If you do not use isocyanate preparative multi dimerization catalyst, the upper limit is usually 1.5 equivalents, preferably 1.3 equivalents. The preferred amount of the polyisocyanate compound used in the present invention is 0.8 to 1.3 times equivalent to the total equivalent of the high molecular weight active hydrogen compound and the chain extender.

The blowing agent used in the present invention is water,
A blowing agent as a main component at least one thermally decomposed to selected from thermally decomposable foaming agent Contact and inert gas to generate gas. Water reacts with the polyisocyanate compound to generate carbon dioxide. Gases generated by the thermal decomposition of the thermal decomposition type foaming agent include carbon dioxide, ammonia, nitrogen gas and the like. Inert gases include air and nitrogen gas. water,
The pyrolytic blowing agent and the inert gas may be used alone or in combination, or may be used in combination with another blowing agent. When used in combination with another blowing agent, the gas amount (volume) generated by the blowing agent in the present invention is preferably larger than the gas amount generated by the other blowing agent.

The pyrolytic foaming agent in the present invention includes:
Pyrolyzed to a small amount selected from carbon dioxide and ammonia
Compounds that generate (release) at least one species are preferred. This pyrolytic foaming agent is thermally decomposed in a high-temperature atmosphere due to reaction heat at the time of polyurethane foam formation to generate gas.
The thermal decomposition temperature is preferably from 40 to 100C, particularly preferably from 50 to 80C. Specific compounds, such as ammonium carbonate, ammonium bicarbonate, include ammonium carbamate, which generates carbon dioxide and ammonia decomposes at about 60 ° C. (release).

As a blowing agent for producing a general thermoplastic resin foam, it is difficult to use a blowing agent that generates ammonia due to environmental problems such as odor. Only
However , in the present invention, such a problem does not occur because the generated ammonia quickly reacts with the polyisocyanate compound and is not released out of the reaction system.

The above-mentioned pyrolytic foaming agent is preferably used by adding it to a high molecular weight active hydrogen compound or a component containing it. In particular, it is preferable to add and disperse the fine powder in a solvent such as a monoalcohol or a polyhydric alcohol or water before adding the solution.

[0060] The amount of blowing agent in the water, etc. is not particularly limited, preferably 0.1 to 10 parts by weight with respect to high molecular weight active hydrogen compound 100 parts by weight, further 0.1 to 5 parts by weight, particularly 0.1 to 3 parts by weight is preferred. Including blowing agent capable of down Symbol combination, the amount of blowing agent can be used to adjust the appropriate amount in response to a request, such as expansion ratio of interest.

In the present invention, the blowing 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) foaming agents, hydrofluorocarbon (HFC) foaming agents, hydrochlorocarbon (HCC) foaming agents,
It is preferable to use a hydrocarbon-based blowing 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 amount of the high molecular weight active hydrogen compound 100
Up to 12 parts by weight, especially up to 8 parts by weight, per part by weight are suitable.

[0062] The blowing agent can be used in combination as described above in the present invention, in particular low-boiling organic compound-based blowing agent, use is not essential, for example, only water in manufacturing good skinned polyurethane foam as a blowing agent Wear. Practically water only
Is preferably used as a foaming agent.

When reacting a polyol with a polyisocyanate compound, it is necessary to use a catalyst. As the catalyst used in the present invention, an active hydrogen-containing group and a isocyanate group of a polyoxyalkylene polyol or a chain extender called a resination reaction, rather than a reaction of water and a polyisocyanate compound called a foaming reaction. The compound which promotes the reaction of is mainly used as a catalyst. As a catalyst for accelerating the resinification reaction, a metal compound catalyst or a certain amine catalyst is effective. Amine-based catalysts mainly used for the production of polyurethane foams are mainly catalysts for promoting a foaming reaction, but some amine-based catalysts have an action to promote a resin-forming reaction more than a foaming reaction. The A Min catalysts keep <br/> the present invention an amine-based catalyst having a function of promoting such gelling reaction is used. A catalyst which promotes relative to a small amount of blowing reaction can also be used with such amine-based catalyst or a metal compound catalyst.

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

The metal compound catalysts usable in the present invention include organic tin compounds, organic bismuth compounds, organic lead compounds and organic zinc compounds. Examples of the amine catalyst having an action to promote the resinification reaction include the following DBU compounds and imidazole compounds.

[0066] DBU (1,8- diazabicyclo [5.
4.0] undecene-7), and its carboxylate,
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;

[0067] Also, the carboxylic acid metal salt and N, N, N-tris (dimethylaminopropyl) hexahydro - s - iso <br/> cyanate preparative multi dimerization catalyst for reacting isocyanate groups comrades such triazines in accordance with the intended used. Triethylenediamine, bis (2-dimethylaminoethyl)
It can be used in combination with a general tertiary amine catalyst which is a catalyst for promoting a foaming reaction such as ether.

In addition to blowing agents and catalysts, foam stabilizers for forming good cells are often used. Examples of the foam stabilizer include a silicone-based foam stabilizer and a fluorine-containing compound-based foam stabilizer. Other optional additives include, for example, fillers, stabilizers, coloring agents, and flame retardants.

The 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 (ie, 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. Component. Optionally, the catalyst or can be injected to form a reaction mixture in a total of three components to another component Yabuawazai (normally used to disperse ~ dissolved in a portion of the high molecular weight polyol).

Conventionally, it has been considered essential to use R-11 as a foaming agent for polyurethane foam with a skin.
However, Ru can form a good skin without the use of CFC-based blowing agents such as R-11, according to the present invention. Moreover, HCFC use of a blowing agent consisting of other low-boiling organic compound to not essential, Ru can form a good skin. That is, by using a polyoxyalkylene polyol having a low degree of unsaturation, a skin can be formed by using only water or a heat-decomposable foaming agent as a foaming agent. Book
In the invention, the thickness of the obtained skin layer is 0.5 mm or less.
Above is preferred.

[0071]

EXAMPLES Hereinafter, specific description is but the present invention is Lena have limited these by the present invention through examples.

Raw Materials Used in Examples and Comparative Examples 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 end of the oxyalkylene chain. Its molecular weight, number of functional groups, oxyethylene group content [EO group content] (% by weight), and degree of unsaturation (m
eq / g) and the hydroxyl value (mgKOH / g) are shown in Table 1. B is a trade name "Jeffamine T5000", which is considered to be a polyoxypropylene triamine obtained by converting a hydroxyl group of a polyoxypropylene triol 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 The amine catalysts F1 to F6 and the metal compound catalysts G1 to G5 shown in Table 2 were used. Among them, F1 and F6 are amine-based catalysts that promote a normal foaming reaction.

IV. As a foam stabilizer H, a commercially available silicone foam stabilizer (trade name “S”)
F-2962 "). V. Blowing agents K1 to K5 shown in Table 2. VI. Polyisocyanate compound Commercially available modified MDI as polyisocyanate compound N.
(Trade name "Coronate 1062"). Its isocyanate group content is 27.0% by weight.

The above-mentioned 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 a reaction injection molding apparatus (high-pressure foaming machine), and the liquid temperature was adjusted to 20 to 40 ° C. Further, the polyol compound, chain extender, a catalyst, etc. Poriisoshi
The mixture of the raw materials other than the anate compound was put into the other raw material tank of the reaction injection molding apparatus, and the liquid temperature was adjusted to 20 to 40 ° C.

Both have an isocyanate index of 10
5 and the mixture was injected. The isocyanate index means 100 times the equivalent of the isocyanate compound relative to one equivalent of the total active hydrogen compound. The injection conditions were: injection pressure 150 kg / cm ² , injection amount 300 g / s
And 300mm x 500mm x 10mm for mold
A mold having the inner dimensions of (t) is used.
The temperature was adjusted to 60 ° C.

The skin formation state of the obtained foam with integral skin, that is, the molded article density (g / c)
m 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]

Example according to the present invention and as is clear in comparison with Comparative Example, in the foaming without using R-11 as a foamed material,
With skin to form a skin follower - Rukoto to produce a beam has been very difficult. Even without using R-11 by using the system shown in the present invention can produce a skinned polyurethane foam, molding property of their effect is also observed to significantly improve.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ identification symbol FI // C08L 75:04 C08G 18/08 (58) Investigated field (Int. Cl. ⁷ , DB name) B26C 45/00 B26C 39 / 00-39/12 C08G 18/08-18/66 C08J 9/02

Claims (7)

(57) [Claims] 1. 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 the following (a) and 0 to 80% by weight of the following (b). high molecular weight active hydrogen compound containing wt%, the main component of a chain extender, and a polyisocyanate compound, water, at least one thermally decomposed to selected from thermally decomposable foaming agent Contact and inert gas to generate gas A method for producing a polyurethane foam molded article with a skin, comprising reacting in a closed mold in the presence of a foaming agent and a catalyst to produce a polyurethane foam molded article with a skin. (A): number of hydroxyl groups 2 to 8, hydroxyl value X (mgKOH /
g) is 3 ≦ X ≦ 60, and when 3 ≦ X ≦ 32.5, the total degree of unsaturation Y (meq / g) is Y ≦ 0.04, and when 32.5 ≦ X ≦ 60, X is X. , Y is a polyoxyalkylene polyol having a relationship represented by 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. The polyoxyalkylene polyol (a) has 2 to 8 hydroxyl groups and a hydroxyl value of 3 to 40 (mg KOH / mg).
g), 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. Wherein the polyoxyalkylene polyol (a) is an oxypropylene group content of 75 wt% or more, a polyoxypropylene polyol of oxyethylene group content of 0 to 20 wt%, to claim 1 or 2 The manufacturing method as described . Wherein the blowing agent consists essentially of only water, the production method according to claim 1, 2 or 3. 5. The amount of foaming agent is 0.1 to 3 parts by weight with respect to high molecular weight active hydrogen compound 100 parts by weight A method according to claim 1, 2, 3 or 4. 6. The obtained skin layer has a thickness of 0.5 mm or more.
The process according to claim 1, 2, 3, 4 or 5 is. 7. A polyurethane foam molded article with a skin is produced by reaction injection molding using two components of a component containing a high molecular weight active hydrogen compound and a chain extender and a component containing a polyisocyanate compound. 1 , 2,
7. The production method according to 3, 4, 5 or 6 .