JPS6312891B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polyurethane elastomer with excellent physical properties by a specific high-pressure mixing method. The present invention relates to a method for producing a polyurethane elastomer with excellent physical properties using a specific high-pressure mixing method using an isocyanate composition comprising an organic polyisocyanate monomer and an isocyanate prepolymer.

Conventionally, urethane elastomers have excellent properties (toughness, elasticity, abrasion resistance, oil resistance, etc.) and have therefore been widely used in automobile parts, industrial parts, sports equipment parts, and the like. The method for producing this urethane elastomer involves first preparing a prepolymer with isocyanate groups at the ends obtained by reacting diol with an excess amount of aromatic diisocyanate, then heating this to about 100°C to defoam it. hardening agents such as aromatic diamines [for example, the most widely used 4,4'-methylenebis(2-
(chloroaniline) (melting point approximately 95℃: trade name MOCA)]
Heat to about 100 to 110℃, mix and heat to about 100℃.
There is a hot melt molding method using a so-called prepolymer method, which has been widely used.

However, this prepolymer method using hot melt molding has many drawbacks and problems that need to be solved as described below. That is, the first
In addition, a solid curing agent (e.g. aromatic diamine)
The prepolymer is mixed and defoamed under heat to prevent precipitation of the curing agent and facilitate defoaming, so aromatic diamines and aromatic diisocyanates contained in the prepolymer are There was a problem with vaporization. In particular, these substances are extremely harmful to human health, and workers are exposed to the risk of inhaling the aromatic diamine dust before melting and the vapors of these volatile substances.Currently, there is no way to completely prevent this danger. Can not do it.
Second, since the aromatic diamine is used after being heated and melted, not only the physical properties of the urethane elastomer deteriorate, but also the color tone etc. change significantly due to heating, resulting in a loss of commercial value as a urethane elastomer product. Furthermore, by heating the prepolymer, the terminal isocyanate groups are activated, which react with the urethane groups constituting the prepolymer to form so-called allophanate crosslinks.
This causes an increase in viscosity and causes a significant decrease in the physical properties of the urethane elastomer. Third, second
Due to the increase in the viscosity of the prepolymer mentioned above, it becomes difficult to maintain the manufacturing process and conditions in a stable state, making mass production by automatic continuous mixing extremely difficult. Fourth, mixing, curing, and post-curing are performed at high temperatures, which consumes a large amount of thermal energy.
There were drawbacks such as high manufacturing costs.

It has been found that such drawbacks can be improved by using a curing agent and an isocyanate composition having a specific composition, and an application has already been filed. (Special application 1974-
43000) The present inventors investigated the molding method of the curing agent and isocyanate composition of this specific composition, and found that a urethane elastomer could be efficiently produced by adopting a specific high-pressure mixing method, and thus arrived at the present invention.

That is, the gist of the present invention is to use a curing agent composition containing a polyamine, a polyol with an average molecular weight of 300 to 4,000, and a catalyst as essential components, a prepolymer with an average molecular weight of 500 to 5,000 having an isocyanate group at the end, and an organic polyisocyanate monomer. The isocyanate composition as an essential component is prepared such that the ratio of the number of isocyanate groups in the prepolymer to the number of amino groups in the polyamine is 0.6:1 to 1.5:1, and the total number of isocyanate groups in the isocyanate composition and the number of amino groups in the polyamine are 0.6:1 to 1.5:1. The curing agent composition and the isocyanate composition are mixed in a mixing chamber at a pressure of 50 to 300 kg/cm ² such that the ratio of the sum of the hydroxyl groups of the polyol is in the range of 0.8:1 to 1.4:1. The method of producing a urethane elastomer is characterized in that the two liquids are mixed by mixing the two liquids by causing a turbulent flow in the liquid, and then the mixed liquid is cast and cured.

The present invention will be explained in detail below.

In the present invention, a preferable example of the polyamine used in the curing agent composition is an aromatic diamine, and the aromatic nucleus of this aromatic diamine includes a halogen atom,
Any substituent such as a trifluoromethyl group or an alkoxycarbonyl group may be introduced.

Examples of such aromatic diamines include 3,
3'-dichlorobenzidine, 4,4'-diamino-
3,3'-dichlorodiphenyl ether, 4,4'-
Diamino-3,3'-dichlorodiphenyl disulfide, 4,4'-diamino-3-chloro-3'-bromodiphenylmethane, 4,4'-methylenebis(2
-trifluoromethylaniline), 4,4'-methylenebis(2-chloroaniline) (MOCA), 4,
4'-methylenebis(2-methoxycarbonylaniline), 4,4'-methylenebis(2,3-dichloroaniline), 4,4'-methylenebis(2,5-
dichloroaniline), etc. Also, p
- or m-phenylenediamine type compounds, such as 2,6-dichloro-p-phenylenediamine, 2-chloro-5-isobutoxycarbonyl-
m-phenylenediamine, 2-chloro-5-isopropoxycarbonyl-m-phenylenediamine, and aminobenzoate compounds such as trimethylene bis(p-aminobenzoate), bis(p-aminobenzoyl)diethylene glycol, Nyl sulfide compounds, such as 1,2-bis(p-aminophenylthio)
Examples include ethane, 1,2-bis(o-aminophenylthio)ethane, and the like. Also, 4-chloro-3,5-diamino-isopropylphenyl acetate, 4-ethoxy-3,5-diaminotrifluoromethylbenzene, bis-[2-(o-aminophenylthio)ethyl] terephthalate, etc. be able to. Further, these polyamines may be used alone or as a mixture. An example of this mixture is 4,4'-methylenebis(2
-Chloroaniline) and 4,4'-methylenebis(2,3-dichloroaniline) in any proportion, or a mixture obtained during the production of the above polyamine, such as aniline and 0-chloroaniline, with acid. Examples include a polyamine mixture obtained by reacting with formalin in the presence of a polyamine. However, to produce polyurethane elastomers with high strength, it is preferred to use a single polyamine.

Moreover, the average molecular weight used in the present invention is 300~
The polyol of 4000 is preferably a long chain with a hydroxyl group at the end, such as polyester glycols such as polyethylene adipate, polybutylene adipate, polypropylene adipate, etc.
Polypropylene ether glycol, polytetramethylene ether glycol, poly(oxypropylene) triol, poly(oxypropylene)
Examples include polyalkylene ether polyols such as poly(oxyethylene) triol, poly(oxypropylene) poly(oxyethylene) poly(oxypropylene) triol, polyester polyols, polybutadiene polyols, and polymer polyols. Further, these polyols may be used alone or as a mixture.

These polyols used in the present invention are generally hygroscopic, and the water contained therein reacts with the isocyanate to form carbamic acid. Since this carbamic acid decomposes at temperatures above about 80° C. and generates carbon dioxide gas, when performing high temperature curing, it is desirable that the water content in the long-chain polyol is 0.02% by weight or less. However, the so-called low temperature curing i.e. 80
When curing at temperatures below ℃, this moisture content is 0.04
There is no problem even if it is about % by weight.

The catalyst added to the curing agent composition of the present invention is preferably one that is soluble in polyols and polyamines, such as triethylenediamine, triethylamine, hexamethylenetetramine, N-alkylmorpholine, N-pentamethyldiethylenetriamine, N-hexamethyltriethylenetetramine, N,N-diethylaniline, N,N-dimethylbenzylamine, N,N-
Dimethyllaurylamine, N,N-dimethylpiperidine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylpropyldiamine, N,N,N',N'- Tetramethyl-1,3-butanediamine, N,N,N',
N'-tetramethylhexamethylene diamine, N,
N,N',N',N'-pentamethyldiethylenetriamine, 1,8-diaza-bicyclo-5,4,0
-undecene, 1,8-diaza-bicyclo-5,
Examples include tertiary amines such as 4,0-undecene-methylammonium methosulfate.
This tertiary amine may be used in combination with other catalysts.
Such catalysts include Lewis acid catalysts such as tetra-n-butyltin, tri-n-butyltin acetate, n-butyltin trichloride, trimethyltin hydroxide, dimethyltin dichloride, dibutyltin laurate,
Organotin compounds such as dibutyltin di-2-ethylhexoate, stannath octoate, etc.
Acetylacetone metal salts such as acetylacetone zinc salt, acetylacetone aluminum salt, acetylacetone cobalt salt etc., naphthenic acid metal salts such as zinc naphthenate, lead naphthenate, cobalt naphthenate etc., phenylmercury acetate, phenylmercury oleate, mercury octoate,
organic mercury compounds, such as mercury naphthanate,
Examples include organic lead compounds such as lead octoate and lead naphthanate, or basic metal salts of organic borate esters and organic boron compounds. In the present invention, it is usually preferable to use the Lewis acid described above in combination with a tertiary amine, but when using a polyamine such as diaminodiphenylmethane, which has an extremely fast reaction rate with an isocyanate,
It is effective to use Lewis acids alone. Furthermore, when a tertiary amine and an organic tin compound are used together, the effect of accelerating deterioration is quite large, so it is necessary to pay sufficient attention to their use. Among the above combination systems, the most preferred is an appropriate combination of a tertiary amine and an acetylacetone metal salt.

On the other hand, as the prepolymer having isocyanate groups at the terminals used in the isocyanate composition of the present invention, polyols can be made into isocyanates by known methods.
In other words, this prepolymer is made by combining, for example, a long-chain polyol, such as a polyether polyol, polyester polyol, polybutadiene polyol, or polymer polyol, with an average molecular weight of 300 to 4,000 and having a hydroxyl group at the end, and an organic polyisocyanate monomer in excess of the chemical equivalent of the hydroxyl group. Quantities, e.g.
Aliphatic diisocyanates such as tetramethylene-1,4-diisocyanate and hexamethylene-1,6-diisocyanate, cyclohexane-1,
Aromatic diisocyanates such as 3- or -1,4-diisocyanate, cyclohexylmethane-4,4-diisocyanate, tolylene-2,4- or 2,6-diisocyanate and mixtures thereof, diphenylmethane-4,4-diisocyanate, etc. By reacting, the average molecular weight is 500~
Prepolymers with 5000 terminal reactive isocyanate groups can be produced.

Furthermore, as the organic polyisocyanate monomer used in the isocyanate composition, there are those used in the production of the above-mentioned prepolymer, and in addition, liquid diphenylmethane diisocyanate modified from diphenylmethane-4,4-diisocyanate. , 2,4-tolylene diisocyanate dimer, m-phenylene diisocyanate, 3,
3'-ditolylene-4,4'-diisocyanate (TODI), 4,4'-biphenyl diisocyanate,
Dianisidine diisocyanate (DADI), 1,
Examples include 5-naphthalene diisocyanate. Among these, tolylene diisocyanate, hexamethylene diisocyanate, liquid diphenylmethane diisocyanate, etc., which are liquid at room temperature, are preferred in terms of reducing the viscosity of the prepolymer. Further, these organic polyisocyanate monomers can be used in a suitable mixture.

Further, as the organic polyisocyanate monomer, in addition to the exemplified diisocyanate compounds, a triisocyanate compound may be appropriately mixed.

In the present invention, the curing agent composition is prepared by dissolving the polyol and polyamine described above and adding one or more catalysts thereto. The polyamine is preferably used in an amount of 5 to 60% by weight based on the polyol. The amount of the catalyst is preferably in the range of 0.05 to 3 parts by weight, particularly preferably in the range of 0.05 to 1 part by weight, per 100 parts by weight of the mixed solution of polyol and polyamine. If the amount of the catalyst is less than 0.05 parts by weight, the catalytic effect will be insufficient, and if it exceeds 3 parts by weight, the catalytic effect will not improve much.

In the present invention, when mixing the isocyanate composition with the curing agent composition, the ratio of the number of isocyanate groups in the prepolymer in the isocyanate composition to the number of amino groups in the polyamine in the curing agent composition is determined.
It is necessary to adjust the ratio to be within the range of 0.6:1 to 1.5:1, preferably within the range of 0.9:1 to 1.1:1. In this case, if the proportion of isocyanate groups in the prepolymer is less than the above-mentioned lower limit, the mixture becomes cloudy and the desired polyurethane elastomer cannot be obtained, and if it exceeds the above-mentioned upper limit, only a polyurethane elastomer with poor physical properties can be obtained.

Furthermore, in the present invention, the ratio of the number of isocyanate groups in the prepolymer and organic polyisocyanate monomer in the isocyanate composition to the sum of the number of amino groups in the polyamine and the number of hydroxyl groups in the polyol in the curing agent composition is 0.8:1. ~1.4:1, preferably 1.05:1 to 1.25:1.
If the amount of isocyanate groups is less than the lower limit of the above range, only a soft plastic resin without elasticity will be obtained.
If the upper limit is exceeded, unreacted isocyanate groups remain and the desired polyurethane elastomer cannot be obtained.

In the method of the present invention, conventionally used polyurethane elastomer antioxidants, ultraviolet absorbers, coloring inhibitors, hydrolysis inhibitors, fungicides, flame retardants, coloring agents, extenders, fillers, etc. It can be added as appropriate depending on the use of the polyurethane elastomer.

In the present invention, the curing agent composition and isocyanate composition described above are mixed to have a specific composition, and a high-pressure mixing method is employed as the mixing method. The high-pressure mixing method used in the present invention refers to a method in which a curing agent composition and an isocyanate composition are mixed using a high-pressure pump such as an axial piston pump or a bottle pump.
It is injected into the mixing chamber at high velocity through a small-bore nozzle at a pressure of 50-300 Kg/cm ² . For jetting, there are methods such as hitting liquids together and hitting two liquids against one wall of a mixing chamber, but any method may be used as long as it mixes the liquids while causing turbulence. The mixing temperature may be room temperature, but if it is necessary to increase the reaction rate during molding, the temperature may be raised within the range of 100°C or less.

As the high-pressure mixer, a commercially available high-pressure foaming machine can be used. For example, foaming machines commercially available from Krauss Matsufuei, Henetske, Admiral, Cincinnati Milacron, etc. can be used as they are. However, it is necessary to use a higher pressure in the present invention than in the case of producing foamed products. After mixing by the above-mentioned method, the mixed solution is cast and cured according to a conventional method to produce a polyurethane elastomer.
That is, a polyurethane elastomer can be produced by curing at room temperature to 120° C. for several minutes to several hours, and then post-curing for several minutes to several hours by a conventional method.

The curing temperature is set appropriately depending on the purpose of the polyurethane elastomer and the actual usage situation.
For example, if rapid curing is required, curing is performed at a high temperature.

This polyurethane elastomer can be used as automobile parts, industrial parts, sports equipment parts, etc., and is also suitable as a steel pipe lining resin.

As described in detail above, according to the present invention, it is possible to miniaturize the mixing device and efficiently produce polyurethane elastomer at low temperatures.

Next, the present invention will be explained in detail with reference to examples. In addition, in the examples, the physical properties of the polyurethane elastomer are
Measured according to the method of JISK6301. The shape of the tensile test piece was No. 3, and the shape of the tear test piece was B type.

Example (A) Preparation of curing agent composition Polytetramethylene glycol (OH value 112,
Average molecular weight 1000) 30kg, MOCA 11.95kg, triethylenediamine 105g, and acetylacetone zinc salt 60g were heated to 100°C and stirred until completely dissolved.

(B) Preparation of isocyanate composition To 30 kg of polytetramethylene ether glycol (OH value 112, average molecular weight 1000), add 2,4
-Add 10.55Kg of tolylene diisocyanate,
The reaction was carried out at 80°C for 8 hours. The isocyanate group concentration of the obtained prepolymer was 6.3% by weight. Next, 4.25 kg of TDI80 (80:20 isomer mixture of 2,4- and 2,6-tolylene diisocyanate) was added and mixed well.

(C) Manufacture of polyurethane elastomer Next, the obtained curing agent composition and isocyanate composition were heated using a high pressure casting machine 2000 manufactured by Admiral Co., Ltd.
Place each in a 2HP/2 tank, 20-30mm
Air dissolved in the liquid was removed while stirring for 2 hours under reduced pressure of Hg. Set the temperature of both liquids to 40
℃, the pressure at the time of discharge is 125 Kg/cm ² , and the pump discharge rate is adjusted so that the mixing ratio of isocyanate composition/curing agent composition is 1.55. Next, both were discharged into a mixing chamber and mixed, the liquid was introduced into a sheet mold using a hose, and left as it was at room temperature to obtain an elastomer. At this time, the prepolymer NCO equivalent/amine equivalent ratio is 1/1, total isocyanate equivalent/
The equivalent ratio of amine + polyol is 1.07. The physical properties of the obtained elastomer after being left at 23° C. and 60% RH for 7 days were as follows.

Hardness (JIS-A) 86 100% tensile modulus 64Kg/cm ² 300% tensile modulus 134Kg/cm ² Tensile strength 330Kg/cm ² Tear strength 73Kg/cm ² Elongation 450% Appearance Transparent homogeneous body

Claims (1)

[Claims] 1. A curing agent composition containing a polyamine, a polyol with an average molecular weight of 300 to 4000, and a catalyst as essential components;
Average molecular weight 500 with isocyanate group at the end
~5000 prepolymer and an organic polyisocyanate monomer as essential components, the ratio of the number of isocyanate groups of the prepolymer to the number of amino groups of the polyamine is 0.6:1 to 1.5:
1. The ratio of the total number of isocyanate groups in the isocyanate composition to the sum of the number of amino groups of the polyamine and the number of hydroxyl groups of the polyol is 0.8:1 to 1.
The curing agent composition and the isocyanate composition are heated at a pressure of 50 to 300 Kg/1.4:1.
1. A method for producing a polyurethane elastomer, which comprises injecting the liquid into a mixing chamber at a volume of cm ² to cause turbulence in the liquid to mix both liquids, and then casting and curing the mixed liquid.