JPH0241310A - Production of polyurea-based elastomer - Google Patents

Abstract

PURPOSE:To obtain the subject elastomer with excellent liquid fluidity by molding a composition mixture consisting of a polyisocyanate, high-molecular weight active hydrogen-containing compound and specific aliphatic diamine in a mold by a reaction injection molding method. CONSTITUTION:The objective elastomer, obtained by molding a composition mixture consisting of (A) a polyisocyanate (preferably a urethane group- containing polyisocyanate prepared by reacting 4,4'-diphenylmethane diisocyanate with low-molecular weight polypropylene glycol, etc.), (B) a high-molecular weight active hydrogen-containing compound (preferably having 1000-18000 molecular weight) and (C) an aliphatic diamine in which at least one of amino groups is converted into secondary amino group by an alkyl or aralkyl group) in a mold by a reaction injection molding method and useful as automotive bumpers, fascias, fenders, doors, side moldings, window gaskets, etc.

Description

Detailed Description of the Invention (Field of Industrial Application) Relatively high-density polyurethane and polyurea elastomer molded products produced by reaction injection molding have excellent physical properties, moldability, and appearance, and are used in a wide range of fields. It is used. Specific examples of applications include a wide range of applications such as automobile plate materials, sports and leisure goods, office equipment housings, furniture, and agricultural equipment.

The most commonly used of these are automobile bumpers, fascias, fenders, doors, side moldings, window gaskets and the like.

(Prior art) Non-foamed polyurethane (including polyurea, hereinafter the same) is produced by polyaddition of isocyanate and active hydrogen-containing compound.
It is known to mold fiber-reinforced elastomers, microcellular polyurethane elastomers, or microcellular polyurethane elastomers by reaction injection molding.

The raw materials for these polyurethanes or polyureas include polyisocyanates, high molecular weight active hydrogen-containing compounds (polyether polyols, polyester polyols, polyether polyamines, etc.), low molecular weight active hydrogen-containing compounds (alkanediols, aromatic polyamines, etc.), And, if necessary, a catalyst, a blowing agent, an additive, and a fibrous inorganic compound.

Reaction injection molding method
n Molding.

(hereinafter abbreviated as RIM) is a method in which an isocyanate and an active hydrogen-containing compound are impact-mixed under pressure (often under high pressure) using an injection molding machine, this mixture is filled into a mold, and the molded product is taken out after hardening. be.

A detailed description of the reaction injection molding method can be found, for example, in the following document: Reaction Injection Moldin
G in the Auto-motive In
industry + Journal of Ce11.
Plastics.

Vol, 2.1975; Plastics for Auto-mobi
le 5afety Bumpers Journal
l of Ce11. Plastics, Vol 2t
1973. Among the above raw materials, chain extenders are particularly important because they have a large effect on moldability and physical properties.

(Problems to be Solved by the Invention) As chain extenders, low-molecular-weight alkanediols or certain aromatic polyamines are used for boat fishing, but they do not always have sufficient performance in terms of molding or physical properties. It is not something that is given.

Specifically, when ethylene glycol is used, cell roughness, loose skin, pinholes, sink marks, and residual molding tend to occur, and when carried out industrially, productivity is extremely low and unsatisfactory.

The above methods have poor physical properties such as curing properties and heat resistance, so
One way to improve this is to use ethylene glycol and aromatic polyamine in combination.

For example, JP-A-52-77200 describes a method for improving curing properties and heat resistance by using ethylene glycol and a polynuclear mixed aromatic polyamine synthesized by condensation of aniline and formalin. ing.

On the other hand, as a method of using an aromatic amine as the main chain extender, for example, as described in Japanese Patent Publication No. 54-17359, hydrogen at the ortho position to each amino group of an aromatic diamine is used. There is a method in which the amino group is substituted with a straight-chain alkyl group having 1 to 3 carbon atoms to reduce the reactivity of the amino group due to steric hindrance, thereby improving the liquid flow into the mold.

The method using this type of aromatic diamine is currently used in the United States because it has faster demolding time and curing time than ethylene glycol and 1,4-butanediol, and has excellent heat resistance and tensile properties. Diethyltoluenediamine (DETDA) shown in the examples of the patent is used in products such as bumpers, fascias, etc.

However, this method has a problem in that when producing a molded product with high modulus, the molded product becomes brittle and easily cracks during demolding. In addition, as another method, for example, JP-A-58-3
There is a method, as disclosed in Japanese Patent No. 2626, in which a halogen-containing diaminobenzene with low reactivity is used as a chain extender.

In this method, the reactivity of halogen-containing diaminobenzene is moderately fast, but curing is too slow and molding is difficult.

Furthermore, aliphatic primary diamines used as chain extenders other than those mentioned above react too quickly and are difficult to use in actual molding.

(Means for Solving the Problem) As a result of intensive research on aliphatic diamine compounds, the present inventors have determined that at least one of the amino groups of an aliphatic primary diamine is secondaryized with an alkyl group or an aralkyl group. It was discovered that liquid flowability was improved by doing so, and the present invention was achieved.

That is, the present invention provides a mixed composition comprising: a) a polyisocyanate, b) a high molecular weight active hydrogen-containing compound, and C) an aliphatic diamine in which at least one of the amino groups is secondaryized with an alkyl group or an aralkyl group. The present invention relates to a method for producing a polyurea-based elastomer molded article, which is characterized by reaction injection molding in a mold.

In the above item C), "aliphatic diamine" 7 means that an amino group is bonded to a carbon atom through an aliphatic bond, excluding aromatic conjugate bonds. however,
Aromatic groups may be included at other positions in the molecule.

Further, the above aliphatic diamine C) may be used in combination with an aromatic primary diamine.

Examples of the [aliphatic diamine in which at least one of the amino groups is secondaryized with an alkyl group or aralkyl group] used in the present invention include N-benzyl-ethylenediamine N-tert-butyl-ethylenediamine N-propyl- Ethylenediamine N-benzyl-N”-phenyl-ethylenediamine N-benzyl-No-tert-butyl-ethylenediamine N-benzyl-No-propyl-ethylenediamine N-benzyl-propylene diamine N-tert-butyl-propylene diamine N-propyl-propylene Diamine N-benzyl-No-phenyl-propylenediamine N-benzyl-No-tertiary-butyl-propylenediamine N-benzyl-No-pro-propylenediamine N-benzyl-α, α9 α゛, α°, α°- Tetramethyl-meth-xylylene diamine Shary-butyl-α, α, α, α Tetramethyl-meta-xylylene diamine N-benzyl-para-xylylene diamine N-tert-butyl-para-xylylene diamine N-benzyl- Isophoronediamine N-tert-butyl-isophoronediamine N-propyl-isophoronediamine N-benzyl-N1-phenyl-isophoronediamine N-benzyl-No-tert-butyl-isophoronediamine N-benzyl-No-propyl-isophoronediamine, etc. be.

In the present invention, examples of the aromatic primary diamine used in combination in some cases include 2,4-diaminotoluene 2,6-cyaminotoluene, phenylenediamine metaphenylenediamine 3,5-diethyl-2,4-diaminotoluene 3 .5-
Diethyl-2,6-diamittoluene 3-isopropyl-2,6-diamittoluene 5-isopropyl-2,4
-diaminotoluene 5-tert-butyl-2,4-
Diaminotoluene 4.4゛-methylene-bis-(2,6-dinithylaniline) 4.4゛-methylene-bis-(2,6-diitubrobylaniline) 44゛-methylene-bis=(2- ethylaniline) 3.4″-diaminodiphenyl-1,1°-ethane 5.7-diamitwo 1.1-dimethylindane 4.6-
Jiami Two 1. l-Dimethylindane 4.7-Diami2 1.1-Dimethylindane 5.7-Diami2 1.1
, 4,6-titramethylindan and the like.

Examples of the polyisocyanate used in the present invention include 4.4°-diphenylmethane diisocyanate, 2.
4- and/or 2,6-toluene diisocyanate,
Polymethylene polyphenyl polyisocyanate, xylylene diisocyanate, isophorone diisocyanate,
These include other aliphatic polyisocyanates and dimers, 3ft bodies, carbodiimide modified products, allophanate modified products, biuret modified products, prepolymers, etc. of these isocyanates.

A particularly preferred isocyanate compound is a modified form of 4,4''-diphenylmethane diisocyanate, which is liquid at room temperature. Specific examples of this compound include;
Urethane group-containing polyisocyanate obtained by reacting diphenylmethane diisocyanate with a low molecular weight diol or triol (preferably polypropylene glycol having a molecular weight of less than 700), or a 4,4'- containing carbodiimide group and/or uretonimine group. Diphenylmethane diisocyanate-based polyisocyanates, and examples of preferred polyisocyanates include products obtained by modifying a mixture of 2,4'- and 4,4'-diphenylmethane diisocyanates as described above, or products modified as described above. It is also a mixture of 4,4'-diphenylmethane diisocyanate and a small amount of diphenylmethane-based polyisocyanate having a degree of functionality higher than difunctionality.

The high molecular weight active hydrogen-containing compound used in the present invention is an active hydrogen compound having a practical molecular weight of 1,000 to 18,000, and specifically includes the following compounds.

As an initiator, polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, l,3,6-hexanetriol, pentaerythritol, sorbitol, etc. Alkanolamines such as tanolamine and triethanolamine, or amines containing two or more active hydrogens such as ethylenediamine, diethylenetriamine, ammonia, aniline, tolylenediamine, xylylenediamine, and diaminodiphenylmethane,
Polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, and styrene oxide;
Alternatively, there are polytetramethylene ether glycols obtained by ring-opening polymerization of tetrahydrofuran.

Further, a polymer polyol obtained by grafting an ethylenically unsaturated compound such as styrene, acrylonitrile, or methyl methacrylate to the above polyol, and 1.
2- or 1,4-polybutadiene polyols or hydrogenated products thereof can also be used.

Furthermore, polyester polyols obtained by reacting polycarboxylic acids with low molecular weight polyols, polyester polyols obtained by ring-opening polymerization of caprolactone, and polycarbonate polyols can also be used.

In addition, for example, a primary or secondary amine obtained by aminating the OH group of the above polyether polyol, specifically a polyether polyol obtained by addition polymerizing propylene oxide to glycerin, in the presence of a catalyst. There are high molecular weight polyether polyamines obtained by reaction with ammonia or monoalkylamines. Also,
A polyether polyamine obtained by chemically bonding a high molecular weight polyether and an aromatic amine may also be used.

When carrying out the present invention, the equivalent ratio of the NGO group and the active hydrogen-containing compound contained in the polyisocyanate is 0.8
The amount of each raw material used is adjusted so that the amount becomes 1.3.

In addition to the above raw materials, auxiliary agents include catalysts, blowing agents, internal mold release agents, fillers, pigments, antioxidants, weathering stabilizers, and the like.

As the catalyst, organometallic catalysts such as diptyltin diacetate, diptyltin dilaurate, tin oleate, tin octoate, and triethylamine, N.

N, N', N'-tetramethylpropanediamine,
1.4-diazabicyclo-(2,2,2)-octane,
There are amine catalysts such as pentamethyldiethylenetriamine.

As a blowing agent, for example, trichlorofluoromethane, C
C1zF-CCI Fg, methylene chloride, water,
There are nitrogen gas, carbon dioxide gas, etc.

As the internal mold release agent, a silicon-based compound or the like is used.

Fillers include glass fiber, flake glass, mica,
Talc, inorganic compound whiskers, etc. are used.

(Function) In the present invention, by using an aliphatic diamine in which at least one of the amino groups is secondaryized with an alkyl group or an aralkyl group, instead of the conventionally known fast-reacting aliphatic primary diamine, Liquid flowability and fragility during demolding are improved.

(Examples) In order to explain the present invention more specifically, Examples and Comparative Examples will be described below, but the present invention is not limited to these Examples.

A mixed solution was prepared using the following raw materials, and RIM molding was performed in a mold using an injection molding machine for polyurethane.

To the aluminum: Triol with a molecular weight of about 5000 obtained by addition polymerizing propylene oxide to glycerin,
Polyethertriamine obtained by reaction with ammonia in the presence of a catalyst, Diefermine T-5000 from Texaco
゜l Technical Cup 2 Saturday and Sunday: A polyoxyalkylene triol with a hydroxyl value of 28 mgKOR/g and a primary hydroxyl group content of 75% obtained by addition polymerizing propylene oxide and ethylene oxide to glycerin.

Amine A: Isocyanate prepolymer with an NCO group content of 22% obtained by reacting 4.4°-diphenylmethane diisocyanate and tripropylene glycol Amine A: ethylenediamine was mixed with benzyl chloride in a dioxane solvent. N-benzyl- obtained by reacting with
Ethylenediamineamine B: α, α, α, α-tetramethyl-meta-
N-tert-butyl-α, α, α, α-tetramethyl-meth- obtained by reacting xylylene diamine with tert-butyl chloride in dioxane solvent
Xylylene diamine m-TDA: rm manufactured by Mitsui Toatsu Chemical Co., Ltd.
- A mixture of 2.4-diaminotoluene and 2.6-diaminotoluene in a weight ratio of 80:20 in TDAJ.

DETDA: rDETDA from Ethyl Corporation
, a mixture of 3.5-diethyl-2,4-diaminotoluene and 3.5-diethyl-2,6-diaminotoluene in a weight ratio of 80:20.

DBTDL n Nitto Kasei's tin catalyst for urethane.

Dibutyltin dilaurate.

B-712: Wax-based external mold release agent for RIM manufactured by Middle East Yushi ■.

Examples 1 to 4 and Comparative Examples 1 to 2 Molding was performed using the raw material formulations listed in Table 1 as Examples and Comparative Examples.

As reaction injection molding machines, NR-230 manufactured by Toho Kikai and LRM-15M manufactured by Cincinnati Milacron were used.

The liquid temperatures of the amine mixture and the isocyanate were each adjusted to 20°C and 140', and nitrogen gas was dissolved in the amine mixture to a concentration of 40% by volume (value in the atmosphere). The blending ratio of the raw materials was adjusted to the amounts shown in Table 1, and the injection speed was as shown in Table 1.

The mold is 500mm x 400mm x 3. Omm (mold A
) and 900mmX600mmX3. Omm (Mold B
) was heated to 75° C., an external mold release agent was applied, and the mold was thoroughly wiped with a dry cloth.

The mold was removed 30 seconds after injection, and the releasability and curing properties were compared. Cure performance was determined by placing the sheet molded product on a horizontal table immediately after demolding, and measuring the height of the drop from the horizontal surface by protruding 20 cm from the tip of the sheet after 1 minute, and determining the quality of the cure performance based on its size. . At the same time, in order to see how brittle the sheets were immediately after being formed, the sheets were bent to see if they would crack.

The surface condition of the molded product was also examined.

Physical properties were determined by cutting a test piece from the molded product, heating it in an oven at 120°C for 1 hour, and then measuring tensile strength, tensile elongation, and bending modulus.

The results are shown in Table 1. In Example 1.2, polyether A
1 and using amine A and amine B as chain extender diamines, the liquid elongation properties were good.

On the other hand, as shown in Comparative Example 1, when aliphatic primary diamine (ethylenediamine) was used alone as the chain extender diamine, the liquid elongation and mixability were quite poor.

Further, as shown in Comparative Example 2, when aromatic diamine (DETDA) was used as the chain extender diamine, the molded product was brittle and easily cracked during demolding.

In Example 3, molding was performed using polyether B (polyol).

In Example 4, a high modulus elastomer was molded using m-TDA and Amine B in combination, but unlike Comparative Example 2, it was not brittle during demolding.

(Effects) As is clear from Examples 1 to 4, it was observed that the method of the present invention showed improved molding performance during injection molding of polyurethane.

Claims (1)

[Scope of Claims] A composition mixture consisting of a) polyisocyanate b) high molecular weight active hydrogen-containing compound c) aliphatic diamine in which at least one of the amino groups is secondaryized with an alkyl group or an aralkyl group is prepared in a mold. A method for producing a polyurea-based elastomer molded article, characterized in that the molded article is molded by a reaction injection molding method.