JPH09183826A - Production of urethane foam formed article having integrated skin layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a formed article excellent in weather resistance and discoloration resistance, good in heat resistance and useful for automobile, etc., by using only a specific isocyanate polymer as an isocyanate. SOLUTION: A resin solution containing (A) an isocyanate, (B) a polyol, (C) a chain extender and (D) a catalyst, and optionally various kinds of assisting agents and additives is injected into a mold at once. In this process, only an isocyanate polymer synthesized from an aliphatic and an alicyclic polyisocyanate (e.g. 1,6-hexamethylene diisocyanate) is used as the component A. Further, an example of a preferable isocyanate polymer to be used is as follows: the polymer contains a polymer component, which forms an isocyanurate ring, in an amount of >=95wt.% and has one isocyanurate ring or more and two NCO groups or more in a molecule at the same time; the unreacted diisocyanate is removed by distillation and then, the isocyanate polymer contains >=10wt.% of a polymer having one isocyanurate ring in a molecule and <=90wt.% of a polymer having two isocyanurate rings or more in a molecule.

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 layer having an integral skin layer, which is excellent in weather resistance and discoloration resistance and has heat resistance.

[0002]

2. Description of the Related Art Generally, a polyurethane foam molded article with an integral skin layer, that is, a polyurethane foam molded article with an integral skin is usually prepared by using an aromatic polyisocyanate, for example, an automobile steering wheel, an arm restraint or a head restraint. It is used for grip parts such as spoilers, furniture, and household electric appliances.

As a method for producing a polyurethane foam molded article with an integral skin layer, a technique for producing a so-called integral skin polyurethane foam molded article by producing a polyurethane foam molded article with an integral skin layer by a one-shot method has been known. ing.

According to this technique, a polyurethane foam molded article having a beautiful surface layer which is a skin layer that replaces the natural leather or the synthetic leather without coating the surface of the molded article with the natural leather or the synthetic leather is cast in a mold in one step. It has been carried out or manufactured by reaction injection molding (so-called RIM technology).
The molding cycle time of this technique is relatively short, about 1 to 10 minutes, and the curing time (cure time) in the mold has been about 1 to 5 minutes.

Therefore, as the organic polyisocyanate in the reaction composition used in this technique, an aromatic polyisocyanate has been usually used. However, it is also known that a polyurethane foam obtained from such an aromatic polyisocyanate produces a compound having a color-forming factor that causes yellowing upon oxidation, and this oxidation is further accelerated by light and heat. .

That is, since the aromatic polyisocyanate is used, there is a drawback that the polyurethane foam itself with the integral skin layer itself turns yellow due to oxygen in the air thermally or under the environment of ultraviolet rays.

As a technique for preventing the deterioration of the product properties due to the discoloration of the surface appearance of the molded product, a non-denatured paint in a mold is applied in advance in manufacturing the molded product in a desired hue for practical use.
A technique is known in which a resin liquid for polyurethane foam is injected to form a molded product whose entire surface is covered with a non-yellowing paint.

[0008] Further, the resulting molded article is post-coated with a non-yellowing paint, and a non-yellowing paint film is added or a large amount of an antioxidant, an ultraviolet absorber, a light stabilizer, etc. is added (hereinafter referred to as an antiaging agent. (Hereinafter referred to as "addition method"), a technique for extending the period until the color change of the polyurethane foam due to the aromatic polyisocyanate is known.

However, although prevention of discoloration by a non-yellowing coating film (hereinafter referred to as a coating film protection method) is effective, there are drawbacks in terms of process, equipment and work. In addition, the antiaging agent addition method has a limit in the discoloration prevention period, which has been a problem from the viewpoint of commercial appearance.

Particularly, regarding the parting surface which is the mating part of the molding die, the burr part generated at the parting part in the finishing step of the molded product is cut and the polyurethane foam layer is exposed as a naked appearance, so that the appearance product It was a big drawback from the point of view of sex.

In order to prevent this, it has been adopted to apply a non-yellowing paint to the cut surface of the parting portion again to form a coating film.

[0012]

Generally, in order to prevent discoloration, an aliphatic system such as hexamethylene diisocyanate, xylene diisocyanate, hydrogenated xylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate (dicyclohexyl 4,4 'diisocyanate) or the like is used. Since polyurethane resins using alicyclic polyisocyanates are excellent in discoloration resistance and weather resistance, these isocyanates are provided as monomers, TMP adducts, burette modified products or trimers. It has been used in the fields of paints, adhesives and sealants.

A technique for using these aliphatic or alicyclic organic polyisocyanates in a polyurethane foam molded article is disclosed in JP-B-54-15599 and JP-A-56.
-28212, JP-A-6-271638,
It is described in Japanese Patent Laid-Open No. 6-220155.

These polyisocyanates use a prepolymer obtained by modifying a monomer or a polyol containing a large amount of the monomer. Therefore, the obtained polyurethane molded product uses a monomer with a high vapor pressure, and there is a problem in terms of environmental hygiene in the manufacturing process, and due to the molecular structure, the initial hardness development including when the molded product is released from the mold. Is insufficient, the heat resistance is particularly poor, and there are many drawbacks such as the liberation of monomers in a thermal environment of 100 to 150 ° C. and the polyurethane foam layer melting during foaming. It was

Conventionally, aliphatic or alicyclic isocyanates have extremely low activity as compared with aromatic polyisocyanates, and therefore their reactivity is also low, resulting in a polyurethane foam molded article with an integral skin layer. Manufacturing by the one-shot method has been considered extremely difficult.

Therefore, the main fields of application of the aliphatic or alicyclic isocyanates are in the fields of paints, adhesives, and sealing agents from the viewpoint that various reaction conditions can be set in a reaction kettle to allow a slow reaction. It was limited.

Further, as a technique for utilizing an aliphatic or alicyclic polyisocyanate in a polyurethane foam molded article, the above Japanese Patent Publication No. 54-15599, JP-A No. 56-28.
No. 212, JP-A-6-271638, JP-A-6-220155 and the like, the technique described here uses the monomers of these polyisocyanates as they are, Alternatively, a monomer is mainly used and a burette body, an adduct body, a trimer polymer, an NCO group-terminated prepolymer, or the like is mixed and used, and further, an aromatic polyisocyanate is mixed with these, so-called fat. There has been proposed a method for producing a polyurethane foam by a one-shot method using an organic polyisocyanate obtained by mixing a group-type or alicyclic polyisocyanate and an aromatic-type polyisocyanate.

As the above manufacturing technique, Japanese Patent Publication No. 54-1559.
No. 9, JP-A-56-28212, JP-A-6-
In the polyurethane foam with integral skin disclosed in Japanese Patent No. 271638 and Japanese Patent Laid-Open No. 6-220155, heat resistance, weather resistance and discoloration resistance are not sufficient, and improvement thereof has been strongly desired.

The inventor of the present invention has found that an aliphatic or alicyclic polyisocyanate is a discoloration-resistant paint and an adhesive for a special purpose requiring a discoloration resistance, a coating film waterproofing agent, a decorative floor surface, or a yellowing-resistant urethane. We have conducted intensive research and explored the reasons why it is mainly used in the field of cement admixtures.

Research and quest have been made that the adducts, burettes and trimers are excellent in yellowing resistance, and among them, the trimers are extremely resistant to discoloration as well as heat stability and weather resistance. We paid attention to the superior point.

Then, a monomer of an aliphatic or alicyclic polyisocyanate or a prepolymer (hereinafter referred to as an adduct) in which a part of the NCO group thereof is added by an active hydrogen compound such as a polyol, or burette to these As a result of intensive studies to improve defects such as heat resistance, weather resistance and discoloration resistance of a polyurethane foam molded article with an integral skin layer using polyisocyanates mixed with a polymer and a trimer, Alternatively, when an isocyanurate polymer obtained by trimerizing an alicyclic polyisocyanate is used, the heat resistance, weather resistance and discoloration resistance are excellent, and the hardness development during molding is also improved. Low reactivity (low activity) that occurs when the above non-aromatic polyisocyanates are used in place of the aromatic polyisocyanates The problem that it was extremely difficult to produce a polyurethane foam molded product with an integral skin layer by the one-shot method was solved, the molding cycle time was sufficiently shortened, and heat resistance, weather resistance, and discoloration resistance were also solved. It was found that a polyurethane foam molded article with an integral skin layer, which has excellent properties and also has an initial hardness development characteristic during molding, can be obtained, and the present invention was accomplished.

An object of the present invention is to provide a method for producing a polyurethane foam molded article with an integral skin layer, which has a high degree of discoloration resistance, heat resistance and weather resistance.

An essential object of the present invention is to provide an industrially and economically valuable process for producing polyurethane foam moldings with integral skin layers which have a high degree of stability against these yellowings. Especially.

[0024]

The method for producing a polyurethane foam molded article with an integral skin layer of the present invention is a resin containing isocyanates, polyols, a chain extender, a catalyst and, if necessary, various auxiliaries and additives. In a method for producing a polyurethane foam molded article with an integral skin layer, which comprises injecting a liquid into a mold with one shot to form a high-density layer on the surface of the molded article, the isocyanates include aliphatic and alicyclic polyisocyanates. It is characterized in that only the synthesized isocyanurate polymer was used.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The organic polyisocyanate used in the present invention contains 95% by weight or more of a polymer forming an isocyanurate ring composed of an aliphatic type and an alicyclic polyisocyanate, and isocyanurate in one molecule. One having at least one nurate ring and at least two NCO groups at the same time, and the isocyanurate polymer thereof has one isocyanurate ring in the molecule by removing unreacted diisocyanate by distillation of the reaction product. It is an isocyanurate polymer consisting of 10% by weight or more and 90% by weight or less having two or more isocyanurate rings. (Hereinafter referred to as isocyanurate polymer)

The aliphatic and alicyclic polyisocyanates used for producing the isocyanurate polymer include:
1,6 hexamethylene diisocyanate (HMDI),
1-isocyanate, 3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (IPDI), tetramethylene diisocyanate, m- and p- xylylene diisocyanate (XDI), 4,4'-methylenebis (cyclohexyl isocyanate) (H ₁₂ - MDI),
1,3-bis (isocyanatomethyl) cyclohexane, 2,2,4-trimethylhexamethylene diisocyanate, dimethylcyclohexane diisocyanate,
2,4-methylenebis (cyclohexyl isocyanate), cyclobutane 1,3-diisocyanate, 2,5
(2,6) -bis (isocyanatotyl) bicyclo (2,6)
2, 1) Heptane (NBDI), etc. Two or more types of isocyanurate polymers produced from these isocyanates can be mixed and used. Of these isocyanates, an isocyanurate polymer from 1,6 hexamethylene diisocyanate is most preferable because it is an aliphatic isocyanate, has a primary isocyanate group, has no steric hindrance, and has good compatibility with other resins. .

In the present invention, the polyol used together with the above-mentioned isocyanurate polymer to obtain a polyurethane foam molded article with an integral skin layer has two or more hydroxyl groups in one molecule and is conventionally used. All polyether polyols and polyester polyols and polymer polyols obtained by reacting polyether polyols with ethylenically unsaturated monomers (eg acrylonitrile, vinylbenzene, methyl methacrylate) (eg disclosed in US Pat. No. 3,383,351). Polyols as described above) can be used, and these polyols can also be used in combination of two or more kinds. The molecular weight of these polyols is 1000 to 10,000.

The polyether polyol is one of compounds having at least two active hydrogen atoms in one molecule.
It is produced by addition-polymerizing alkylene oxide (for example, ethylene oxide, propylene oxide, etc.) using one kind or two or more kinds as an initiator. Examples of the compound having at least two active hydrogen atoms used here include ethylene glycol, propylene glycol, glycerin, trimethylolpropane, triethanolamine, pentaerythritol, sorbitol,
There is sucrose.

The polyester polyol is a compound used as an initiator of a polycarboxylic acid and the above polyether polyol, and is a compound having two or more hydroxyl groups in one molecule, such as ethylene glycol, propylene glycol and trimethylolpropane. As the polycarboxylic acid, one or more compounds having at least two carboxyl groups in one molecule such as adipic acid, maleic acid, succinic acid and malonic acid can be used and can be produced by a known method. Of course, a polyester polyol obtained by ring-opening polymerization of caprolactone can also be used.

As a chain extender, at least 2 in one molecule
It is a low molecular weight compound with 1 active hydrogen and has a hydroxyl equivalent of 1
00 or less, such as ethylene glycol, diethylene glycol, glycerin, trimethylolpropane,
1,4-butanediol, pentaerythritol, diglycerin, ethylenediamine, triethanolamine and the like and addition of alkylene oxide to these are used. The chain extender is used in an amount of 3 to 15% by weight based on the polyol component.

As the foaming agent used in the present invention, all the foaming agents used for ordinary polyurethane foams, that is, flexible foams and semi-rigid foams can be used. A typical example thereof is a halogenated hydrocarbon which is a physical blowing agent,
For example, 1,1-dichloro-1-fluoroethane (HCF
C-141b), 1,1,1,2-tetrafluoroethane (HFC-134a), 3,3-dichloro-1,1,
1,2,2-Pentafluoropropane (HCFC-22
5ca), a low boiling point hydrocarbon compound such as dichloromethane (so-called methylene chloride) and easily volatile butane, hexane, heptane, isopentane, methyl formate and a chemical foaming agent that reacts with isocyanates to generate water with gas generation. Can be used. You may use these individually or in mixture of 2 or more types.

In the polyurethane foam molded article with an integral skin layer using only the isocyanurate polymer from the aliphatic and alicyclic polyisocyanates in the present invention, preferably water and a low boiling point hydrocarbon compound are used. It is effective to use both water and water alone. Further, the amount of the foaming agent used is 0.
The amount of the halogenated hydrocarbon or the low boiling point hydrocarbon compound as the physical blowing agent is 1 to 1.5% by weight, and the amount thereof is 3 to 15% by weight, and these are used alone or in combination.

As the catalyst used in the present invention, all tertiary amines and salts thereof used in ordinary polyurethane foams and metal compound catalysts such as organic tin compounds can be used. See US Pat. No. 3,79 for these catalysts.
9,898, Japanese Patent Publication No. 52-43517, Japanese Patent Publication No. 53
No. 14279 and Japanese Patent Publication No. 54-15599, among these catalysts, 1,4-diazabicyclo (2,2,2) octane and 1,8-diaza-bicyclo-
(5,4,0) Undecene-7 (DBu sold by San-Apro Ltd.) and its salts, bis- (2-dimethylaminoether) ether, N, N, N ′, N′N′-pentamethyldiethylenetriamine and A combination of higher fatty acid stannous tars such as dibutyltin dilaurate (DBTDL) is desirable and most effective. Further, the blending amounts thereof are 4% by weight or less of the tertiary amine and 3% by weight or less of the organic tin compound with respect to the polyol component, and these catalysts may be used in combination.

As the auxiliaries and additives used in the present invention, various kinds of surfactants, colorants and the molded article of the present invention per se are sufficiently resistant to discoloration under the influence of oxygen, light or heat. Although it has heat resistance, heat resistance and weather resistance, it is desirable to use an antioxidant, a light stabilizer and an ultraviolet absorber in order to further improve these characteristics. Further, auxiliaries and additives such as polybutene and liquid paraffin which can contribute to promoting the skin formation of the polyurethane foam molded article with the integral skin layer in the one-shot method from the viewpoint of physical effects can be used.

As described above, the method for producing a polyurethane foam molded article with an integral skin layer according to the present invention uses only isocyanurate polymers synthesized from aliphatic and alicyclic polyisocyanates as isocyanates. An integral skin layer for forming a high-density layer on the surface of a molded product by injecting a resin solution containing conventionally known polyols, chain extenders, catalysts and, if necessary, various auxiliaries and additives into a mold in one shot. It is a method for producing a polyurethane foam molded article having a NCO index of 80 to 120 by the RIM technology (reaction injection molding, that is, called reaction injection molding), and the activity of the isocyanurate polymer used. 20 ~
The optimum temperature range may be selected in advance by a test in a liquid temperature range of 60 ° C. and a mold temperature of 40 to 70 ° C.

In this case, the low boiling point hydrocarbon compound used in combination with water which is a chemical blowing agent used as a blowing agent has a boiling point range of 20 to 70 ° C. according to the above temperature settings,
The integral skin layer may be selected from those having a good balance between the skin formation of the polyurethane foam molded product and the foaming and gelling of the resin liquid, and usually 10 to the set mold temperature is selected.
A low boiling point hydrocarbon compound having a lower boiling point of 30 ° C. is effective.

[0037]

INDUSTRIAL APPLICABILITY In the polyurethane foam molded article with the integral skin layer according to the present invention, only the isocyanurate polymer polymerized from aliphatic and alicyclic isocyanates is NCO.
Since it is used as, it is excellent in discoloration resistance, heat resistance, and weather resistance, so it is not necessary to protect the coating film by additional coating on the parting part which is the mold matching surface, It can be colored in any desired color tone and can be used in a wide range of applications such as steering wheels for automobiles and game machines, arm restraints, head restraints, grips for spoilers and furniture, or household electric appliances.

[0038]

EXAMPLES The present invention will be described below with reference to examples. In Examples and Comparative Examples, parts and% are by weight unless otherwise specified. Examples; Examples 1 to 4,
The characteristics of the blends of Comparative Examples 5 to 7 and the obtained polyurethane foam molded article with an integral skin layer are shown in Tables 1 and 2. The raw materials used in the examples and comparative examples are as follows.

Polyol 1; polyether polyol having a hydroxyl value of 34 (trade name FA-951 manufactured by Sanyo Chemical Industry Co., Ltd.)

Catalyst 1; triethylenediamine (trade name Dabco of Sankyo Air Products Co., Ltd.) 2; mixed solution of 70% bis- (2-dimethylaminoethyl) ether and 30% DPG (Kao Corporation trade name Kab.
izerNo. 12) 3; dibutyltin dilaurate (product name u-100 of Nitto Kasei Co., Ltd.)

Isocyanate 1; HDI (1.6 hexamethylene diisocyanate) isoiyanurate polymer (trade name of Coronate HX, trade name of Nippon Polyurethane Industry Co., Ltd., NCO content 21.3)
% Isocyanate monomer content 0.6% or less) 2; TMP of XDI (xylene diisocyanate)
(Tristyrolpropane) adduct (trade name of Takeda Pharmaceutical Co., Ltd., D-110N, NCO content: 11.1% 3; HDI (1.6 hexamethylene diisocyanate) (trade name: HDI of Nippon Polyurethane Industry Co., Ltd.) , Purity 99.9%, hydrolyzable chlorine 0.004%) 4; carbodiimide-modified MDI (Mitsubishi Kagaku Dow Co., Ltd.)
Trade name: Isonate-143L, NCO content 29.
0%) 5: MDI prepolymer modified by polyether polyol (trade name: Isonate-1 of Mitsubishi Kagaku Dow Co., Ltd.)
81, NCO content 23.1%)

Crosslinking agent and chain extender 1; ethylene glycol (EG) 2; polyether polyol having a hydroxyl value of 520 (trade name CA-235 manufactured by Sanyo Chemical Industry Co., Ltd.)

[0043] foam stabilizer 1; silicone-based foam stabilizer (trade name: SRX-274C of Dow Corning Toray Co., Ltd.)

Foaming agent 1; H.CFC-141b (trade name of Daikin Industries, Ltd., Daiflon-1416) 2; Distilled water

The deterioration inhibitor TinuvinB-75 heat and antioxidants as light stabilizers, UV absorbers Hin gate amine light stabilizer of brand-name products (liquid) (trade name of Ciba-Geigy Japan Co., Ltd.)

[0046]

[Table 1]

Specimen for discoloration test As shown in Table 1, from the urethane raw material mixture liquid, 10 ^t × 15
Example 1 using a test piece mold of 0 × 160
4 and Comparative Examples 5 to 7 were obtained to obtain 10 ^t
It was cut into × 50 × 60 and used as a specimen for the following test.

Lightfast discoloration test The ratio of discoloration after 100 hours was measured with an ultraviolet carbon fade meter (manufacturer, Suga Test Co., Ltd. FAL-5H) using a chromaticity meter and expressed as a color difference value (ΔE) (A- Two
゜).

Natural Exposure Discoloration Test A natural exposure test was carried out for one year, and the degree of discoloration was visually observed and evaluated.

[0050]

[Table 2]

The characteristics of the blends of Examples 1 to 4 and Comparative Examples 5 to 7 and the obtained one-piece polyurethane foam molded article with a skin layer are shown in Tables 1 and 2. From the results in Table 2, Examples 1, 2, and 3 using Coronate HX, which is an HDI isocyanurate polymer, show the best color fastness. In Comparative Example 5, the center of the foam melted and became hollow due to the temperature scorch during free foaming. Comparative Examples 6 and 7
As shown in Table 2, good results were not obtained with the test piece using the so-called aromatic polyisocyanates.

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Claims (1)

[Claims] 1. A high-density layer is formed on the surface of a molded product by injecting a resin solution containing isocyanates, polyols, a chain extender, a catalyst and, if necessary, various auxiliaries and additives into a mold in one shot. In the method for producing a polyurethane foam molded article with an integral skin layer, an isocyanurate polymer synthesized from aliphatic and alicyclic polyisocyanates alone is used as the isocyanate, with an integral skin layer Method for producing polyurethane foam molded article.