JP3277591B2 - Polyurethane molding composition and method for producing molded article using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyurethane molding composition. More specifically, using a hexamethylene diisocyanate polymer having an isocyanurate ring and an NCO-terminated prepolymer as an organic polyisocyanate, and forming a high-density skin layer comprising a polyol, a chain extender, a foaming agent, and a catalyst. The present invention relates to a polyurethane molding composition for a product and a method for producing a molded product.

[0002]

2. Description of the Related Art In recent years, polyurethane moldings having a high-density skin layer have been used, for example, as handles for automobile parts, instrument panels, armrests, headrests, bumpers, spoilers, etc., or shoe soles and housings of various equipment. Have been done. However, these molded products have a drawback that they usually turn yellow due to sunlight or the like because aromatic polyisocyanates are usually used as polyisocyanates. For this reason, when producing colored products, the discoloration is limited to those that are inconspicuous, such as black or brown. If a light-colored system is required, use a pre-coating (inmold coating) or post-coating coating protection method. Alternatively, a method of adding a large amount of an antioxidant or an ultraviolet absorber is employed.

[0003] However, although the coating film protection method is effective for discoloration, there are difficulties in the process and work, and the additive method has a limit in preventing discoloration. Polyurethane resins using hexamethylene diisocyanate (hereinafter referred to as HDI) to prevent discoloration are known to have excellent weather resistance,
It is usually provided as a polyol adduct of HDI or a modified burette, and is mainly used in the fields of paints and adhesives.

[0004] Methods of utilizing aliphatic or alicyclic polyisocyanates in molded articles are described in JP-B-54-15599, JP-A-56-28212, and the like. Is used as a monomer or a prepolymer containing a large amount of a monomer is used. Usually, since a polyurethane molded product is produced under the condition that a raw material and a mold are heated, use of a monomer having a high vapor pressure has a problem in safety and health. In addition, HDI
When used in the method described herein, there are disadvantages such as difficulty in obtaining hardness due to molecular structure and poor heat resistance.

[0005]

SUMMARY OF THE INVENTION The present inventors have paid attention to the excellent discoloration resistance of HDI, and have conducted various studies to improve the disadvantages of the HDI monomer. As a result, the HDI polymer and the NCO-based terminal prepolymer have been studied. It has been found that by using a polymer together with a polymer, the molded article is imparted with appropriate hardness and excellent heat resistance, and at the same time, the discoloration resistance is improved and the curability is also improved.

[0006]

That is, the present invention relates to a molding composition comprising an organic polyisocyanate, a polyol 1, a chain extender, a blowing agent and a catalyst, wherein the organic polyisocyanate forms an isocyanurate ring. 10 to 90% by weight of an HDI polymer containing 10% by weight or more of a monomer and 90 to 10% by weight of an NCO-terminated prepolymer for polyurethane molding for a molded article having a high-density skin layer. And a method for producing a molded article using the composition.

[0007] The organic polyisocyanate used in the present invention is obtained by converting an HDI trimer forming an isocyanurate ring into one.
It comprises 10 to 90% by weight of an HDI polymer (hereinafter simply referred to as HDI polymer) containing 0% by weight or more and 90 to 10% by weight of an NCO-terminated prepolymer. The HDI polymer has one or more isocyanurate rings in one molecule and NC
It has two or more O groups at the same time. The isocyanurate polymer is produced by using a tertiary amine, an alkyl-substituted ethyleneimine, a tertiary alkylphosphine, a metal salt of acetylacetone, a general formula CnH _{2n + 1} C as a catalyst.
The potassium or sodium salt of an organic acid represented by OOH is used alone or in combination, and if necessary, a co-catalyst is used in combination,
The reaction can be performed at 100 ° C. or lower. Catalysts that can be used include tributylphosphine, lithium acetylacetone and propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid and the potassium or sodium salts of these branched fatty acids. . At the same time as these catalysts,
When a phenolic hydroxy compound, an alcoholic hydroxy compound, or a tertiary amine is used as a cocatalyst, the reaction proceeds more easily. The catalyst can be rendered inactive by using known strong acids as terminating agents, such as phosphoric acid, sulfuric acid and the like. The HDI polymer can be obtained from the reactant by removing unreacted diisocyanate by distillation. HD obtained by such a method
The NCO content of the I polymer is between 17.0 and 23.5% by weight. The HDI polymer has 10% by weight or more of a polymer having one isocyanurate ring in the molecule, and 90% by weight or less of the polymer having two or more isocyanurate rings in the molecule.

The polyisocyanate for obtaining the NCO-terminated prepolymer of the present invention includes aromatic, aliphatic and
An alicyclic polyisocyanate or the like is used. As the aromatic polyisocyanate, for example, 2,4- or 2,6-
Toluylene diisocyanate, naphthylene-1,5-diisocyanate, 4,4 ', 4 "-triisocyanatotriphenylmethane, 2,4,6-triisocyanatotoluene, or aniline-formaldehyde condensation and subsequent phosgenation Polyphenyl polymethylene polyisocyanate (hereinafter referred to as Polymeric MDI
Diphenylmethane diisocyanate (hereinafter referred to as M
DI) and examples of the aliphatic or alicyclic polyisocyanate include tetramethylene diisocyanate, decamethylene diisocyanate, and cyclobutane-
1,3-diisocyanate, cyclohexane-1,3-
And -1,4-diisocyanate, 1-isocyanato-
3,3,5-trimethyl-5-isocyanatomethylcyclohexane (hereinafter referred to as IPDI), perhydro-2,
4- and / or -2,6-diisocyanatotoluene or perhydro 2,4'- and / or -4,4'-diisocyanatodiphenylmethane, HDI and the like.

Preferred NCO-terminated prepolymers are prepolymers using aromatic polyisocyanates, particularly preferably 2,2'-MDI, 2,4'-M
DI, 4,4'-MDI, polymeric MDI or the like, or a mixture thereof, or a compound obtained by modifying a part of these isocyanates with biuret, allophanate, carbodiimide, oxazolidone, amide, imide, etc., and an active hydrogen group-containing compound. It is obtained by reacting with an excess of isocyanate groups. The NCO content of such a prepolymer is between 16.0 and 30.0% by weight.

Compounds having an active hydrogen group for obtaining an NCO group-terminated prepolymer include low molecular polyols,
Examples include polyether-based polyols, polyester-based polyols, castor oil-based polyols, and polycarbonate polyols. These can be used alone or as a mixture of two or more. As the low-molecular polyol, divalent ones such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, hydrogenated bisphenol A, etc. Examples of (trivalent to octavalent) include glycerin, trimethylolpropane, hexanetriol, pentaerythritol, sorbitol, and souce. The low molecular polyol has a molecular weight of 62 to 500, and the other polyols have a molecular weight of 300 to 5000.

The polyether polyol has a molecular weight of 3
For example, ethylene glycol,
Diethylene glycol, propylene glycol, glycols such as dipropylene glycol, glycerin, trimethylolethane, trimethylolpropane, polyols such as pentaerythritol ethylene oxide,
Hydroxy group-containing polyether polyols obtained by addition-polymerizing an alkylene oxide such as propylene oxide. Polyester polyol has a molecular weight of 3
For example, ethylene glycol,
Diethylene glycol, triethylene glycol, 1,
2-propylene glycol, trimethylene glycol,
One or two monomolecular compounds having two or more hydroxyl groups such as 1,3- or 1,4-butanediol, 1,6-hexanediol, decamethylene glycol, glycerin, trimethylolpropane, pentaerythritol, and sorbitol. A monomolecular compound having two or more carboxyl groups such as adipic acid, succinic acid, malonic acid, maleic acid, tartaric acid, sebacic acid, phthalic acid, terephthalic acid, isophthalic acid, trimellitic acid, or a castor oil fatty acid A lactone ester obtained by a ring-opening polymerization of ε-caprolactone, methyl-δ-valerolactone, or the like, or a lactone ester obtained by a condensation reaction with one or more species or the like is used.

The castor oil-based polyol has a molecular weight of 300 to 5,000. For example, castor oil and castor oil or castor oil fatty acid are transesterified with the low-molecular polyol, polyether polyol or polyester polyol, or esterified polyol. Is mentioned.
As the polycarbonate polyol, a molecular weight of 300 to
5,000, for example, obtained by a dealcoholization condensation reaction of a glycol with a dialkyl carbonate such as dimethyl or diethyl, a phenol condensation reaction of a glycol with diphenyl carbonate, or a deethylene glycol condensation reaction of a glycol with ethylene carbonate. Things. Examples of the glycols include aliphatic diols such as 1,6-hexanediol, diethylene glycol, propylene glycol, 1,4-butanediol, 3-methyl-1,5-pentanediol, and neopentyl glycol; ,
Alicyclic diols such as 4-cyclohexanediol and 1,4-cyclohexanedimethanol are exemplified.

In the present invention, the polyol 1 used together with the organic polyisocyanate to obtain a polyurethane molding composition has two or more hydroxyl groups in one molecule and has conventionally been used for producing a polyurethane molding. Anything that has been done can be used. Examples thereof include polyether polyol, polyester polyol, polybutadiene polyol and the like. These polyols can be used in combination of two or more.
Moreover, these molecular weights are 500-10,000.

Examples of polyether polyols include active hydrogen atoms such as ethylene glycol, diethylene glycol, triethylene glycol, trimethylolpropane, glycerin, sorbitol, sucrose, bisphenol A, water, ethylenediamine, tolylenediamine, diphenylmethanediamine and the like. By subjecting one or more monomers such as ethylene oxide, propylene oxide and epichlorohydrin to addition polymerization by a known method using one or more compounds having at least two of the following as an initiator.

As the polyester polyol, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol,
1,3-butanediol, 1,4-butanediol, tetramethylene glycol, hexamethylene glycol,
One or more compounds having at least two or more hydroxyl groups such as glycerin, trimethylolpropane, pentaerythritol and sorbitol, and malonic acid, maleic acid, succinic acid, adipic acid, tartaric acid,
It can be produced by a known method using one or more compounds having at least two carboxyl groups such as sebacic acid and terephthalic acid. Also,
Polyester polyols such as those obtained by ring-opening polymerization of caprolactone are also included. As the chain extender used in the present invention, for example, ethylene glycol, butanediol, diethylene glycol, dipropylene glycol, propylene glycol, glycerin, trimethylolpropane, diethanolamine, triethanolamine, tolylenediamine, hexamethylenediamine,
It is a low-molecular compound having at least two active hydrogen groups, such as methylenebis-o-chloroaniline.

As the foaming agent used in the present invention, all those used in the production of polyurethane foaming agents can be used. These blowing agents are classified into reactive blowing agents and non-reactive blowing agents, and the reactive blowing agents include water. Examples of non-reactive blowing agents include trichlorofluoromethane (e.g., CFC-11), dichlorotrifluoroethane (e.g., HCFC-123), dichloromonofluoroethane (e.g., HCFC1416), tetrafluoroethane (e.g., HFC-134a), Monochlorodifluoromethane (for example, HCFC-22), 1,1,1,4,4
Examples thereof include halogenated hydrocarbons such as 4-hexafluorobutane and dichloromethane, and low boiling compounds such as isopentane and methyl formate. These may be used in combination of two or more depending on the purpose of use. As the catalyst used in the present invention, all those used for producing polyurethane can be used. For example, U.S. Pat.
Tertiary amines, diazabicycloalkenes and salts thereof, and organometallic compounds described in US Pat.

In obtaining a molded article using the composition of the present invention, various surfactants, coloring agents such as dyes and pigments, reinforcing materials and fillers such as mica and glass fibers, flame retardants, Antioxidants, UV absorbers, other auxiliaries and additives can be used. The polyurethane molded article having a high-density skin layer of the present invention can be cast or injected (R).
NCO index 70-1 by means such as IM technology)
It is produced in the range of 40, preferably 90-120. In this case, the reaction can be promoted by heating the raw materials and the mold as necessary.

[0018]

The molded article obtained from the composition of the present invention has excellent weather resistance and discoloration resistance, and can be colored in any desired color tone without additional treatment such as protection by a coating film. , And the use of isocyanurated polyisocyanate has improved heat resistance,
It can be used for a wide range of uses such as instrument panels and shoe soles.

[0019]

EXAMPLES The present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In the examples, all parts and percentages are by weight unless otherwise indicated.

Production of HDI Polymer (A) A-1 300 parts of HDI was placed in a 500 ml glass four-necked flask equipped with a sliding lid equipped with a thermometer, a stirrer, and a nitrogen sealed tube, and potassium caprate 0.3 was used as a catalyst. The air in the flask was replaced with nitrogen and heated to a reaction temperature of 45 ° C. while stirring. The reaction was carried out at the same temperature for 5 hours, and the NCO content was measured. As a result, it was 42.0%, and the reaction solution was a pale yellow transparent liquid. 0.2 parts of phosphoric acid was added as a terminator to the reaction solution, and the mixture was stirred at the reaction temperature for 1 hour, and then unreacted HDI was removed by a molecular distillation apparatus. The resulting liquid was a pale yellow transparent liquid having an NCO content of 23.0%, a trimer content of 53.0%, and free HDI of 0.3%. This HDI polymer is A-
Let it be 1.

A-2 Using the same apparatus as in A-1, 300 parts of HDI, 0.3 parts of tributylphosphine as a catalyst and 0.2 parts of phenol as a cocatalyst were added, and the air in the flask was replaced with nitrogen. The mixture was heated to a reaction temperature of 80 ° C. while stirring. The mixture was reacted at the same temperature for 5 hours and the NCO content was measured.
%, The reaction was a pale yellow transparent liquid. 0.21 part of phosphoric acid as a terminator was added to this reaction solution, and
After stirring for an hour, unreacted HDI was removed by a molecular distillation apparatus. The obtained liquid was a pale yellow transparent liquid having an NCO content of 22.2.
0%, trimer content 46.0%, free HDI 0.3%. This HDI polymer is designated as A-2.

A-3 Using the same apparatus as in A-1, 300 parts of HDI and 0.5 part of lithium acetylacetone as a catalyst are charged, and the air in the flask is replaced with nitrogen. Heated. The reaction was carried out at the same temperature for 6 hours, and the NCO content was measured. As a result, it was 34.0%, and the reaction solution was a pale yellow transparent liquid. 0.5 part of phosphoric acid was added as a terminator to the reaction solution, and the mixture was stirred at the reaction temperature for 1 hour, and then free HDI was removed by a molecular distillation apparatus. The obtained liquid was a pale yellow transparent liquid having an NCO content of 19.0%, a trimer content of 29.0%, and free HDI of 0.3%. This HDI polymer was designated as A-3
And

Production of NCO-terminated prepolymer (B) B-1 318 parts of MDI (manufactured by Nippon Polyurethane Industry Co., trade name: Millionate MT) and 15 parts of diethylene glycol were mixed at 80 ° C. using the same apparatus as in A-1. Let it react for NC
A prepolymer having an O content of 28.5% and a viscosity of 80 cps / 25 ° C. was obtained. This prepolymer is designated as B-1.

B-2 Using the same apparatus as in B-1, carbodiimide-modified MDI
(Millionate MT, manufactured by Nippon Polyurethane Industry
L) 233 parts of PPG-2000 (Asahi Denka polyether) 67 parts was reacted at 80 ° C. for 4 hours to obtain an NCO content of 2
A 2.1% prepolymer having a viscosity of 300 cps / 25 ° C. was obtained. This prepolymer is referred to as B-2.

B-3 300 parts of MDI consisting of 20 parts of 2,4'-MDI and 80 parts of 4,4'-MDI and 10 parts of 1,3-butanediol were heated at 80.degree. For 4 hours, NCO content 29.1%, viscosity 70cps / 25 ° C
Was obtained. This prepolymer is designated as B-3.

Preparation of Organic Polyisocyanate Preparation of HDI Polymer HDI polymer obtained in (A) and NCO
Preparation of group-terminated prepolymer An organic polyisocyanate was prepared from the NCO-group-terminated prepolymer obtained in (B).
Table 1 shows the results.

[0026]

[Table 1]

Examples 1-3, Comparative Examples 1-2 100 parts by weight of polyether polyol (Exenol 845 manufactured by Asahi Glass) 10 parts by weight of ethylene glycol, HC
A premix consisting of 5 parts by weight of FC-123, 331.0 parts by weight of TEDA-L, 1 part by weight of dibutyltin dilaurate, 0.8 parts by weight of Irganox 1010 (manufactured by Ciba Geigy) and the isocyanate shown in Table 2 at 30 ° C. The mixture was heated and mixed at an NCO index of 105. The mixture was poured into an open mold for free foaming and poured into a 10 × 300 × 300 mm mold adjusted to 50 ° C. to obtain a molded product. Table 2 shows the foaming speed during free foaming and the physical properties of the molded product.

[0028]

[Table 2]

Examples 4 to 6 100 parts by weight of polyether polyol (Exenol 845 manufactured by Asahi Glass) 10 parts by weight of ethylene glycol, HF
A premix consisting of 3 parts by weight of C-134a, 331.0 parts by weight of TEDA-L, 1 part by weight of dibutyltin dilaurate, 0.8 part by weight of Irganox 1010 (manufactured by Ciba-Geigy) and the isocyanate shown in Table 3 at 25 ° C.
The mixture mixed at an NCO index of 105 was poured into an open mold for free foaming, and poured into a 10 × 300 × 300 mm mold adjusted to 50 ° C. to obtain a molded product. Table 3 shows the foaming speed during free foaming and the physical properties of the molded product.

[0030]

[Table 3]

Examples 7 to 12, Comparative Examples 3 and 4 100 parts by weight of polyether polyol (Exenol 845 manufactured by Asahi Glass) 5.5 parts by weight of ethylene glycol
0.6 parts by weight of water, 1.0 parts by weight of TEDA-L33,
A premix consisting of 1 part by weight of dibutyltin dilaurate, 0.8 part by weight of Irganox 1010 (manufactured by Ciba Geigy) and the isocyanate shown in Table 3 were adjusted to 30 ° C., and a mixture obtained by mixing at an NCO index of 105 was opened. Pour into the mold and let it foam freely,
The mixture was poured into a 10 × 300 × 300 mm mold adjusted to 50 ° C. to obtain a molded product. Table 4 shows the foaming speed during free foaming and the physical properties of the molded product.

[0032]

[Table 4]

Claims (2)

(57) [Claims] 1. A molding composition comprising an organic polyisocyanate, a polyol 1, a chain extender, a foaming agent and a catalyst, wherein the organic polyisocyanate contains 10% by weight of hexamethylene diisocyanate trimer forming an isocyanurate ring. Hexamethylene diisocyanate polymer containing 10 to 90% by weight and NCO-terminated prepolymer 90 to 90%
A polyurethane molding composition for a molded article having a high-density skin layer, which is 10% by weight. 2. A process for producing a molded product comprising an organic polyisocyanate, a polyol 1, a chain extender, a foaming agent and a catalyst, wherein the organic polyisocyanate is a hexamethylene diisocyanate trimer forming an isocyanurate ring in an amount of 10% by weight. 10 to 90% by weight of a hexamethylene diisocyanate polymer containing at least
A method for producing a molded article having a high-density skin layer, which is 10% by weight.