JPH01152118A - Reaction injection molding method - Google Patents

Abstract

PURPOSE:To obtain a molded item of a polyurethane elastomer having improved heat resistance, by carrying out reactive injection molding using a component contg. a high MW active hydrogen compd. and a specified chain extender and a component contg. a polyisocyanate compd. CONSTITUTION:In a method for preparing a synthetic resin molded item by means of reactive injection molding using at least two components which are a raw material component wherein a high MW active hydrogen compd. and a chain extender are contained and a catalyst and a foaming agent are optionally compounded and a raw material component contg. polyisocyanate compd., a combination of a polyol compd. (A) having a MW of 400 or lower and an arom. compd. (B) having at least two aminoalkyl groups in its arom. nucleus or a combination of these compd. and furthermore another chain extender (C) is used as the chain extender. As the arom. compd. (B), a benzene deriv. having two 1-4C aminoakyl groups is pref.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a reaction injection molding method for molding polyurethane urea elastomer molded articles.

[Prior Art] The production of synthetic resin molded articles by the reaction injection molding method is well known and is widely used, in particular, for the production of polyurethane resin molded articles including polyurethane elastomers. Application to synthetic resins other than polyurethane resins is also known; for example, application to polyamide resins, epoxy resins, unsaturated polyester resins, etc. is being considered, and some of them have been put into practical use by zero-reaction injection. The molding method involves mixing at least two fluid raw materials that can rapidly react to form a synthetic resin when mixed, immediately before a mold, and immediately injecting the synthetic resin into the mold. This is a molding method that focuses on forming Mixing of fluid raw material components is usually carried out by impingement mixing, and in order to achieve more uniform mixing, it is also common to inject the mixture into a mold through an after-mixing mechanism. below,
A mixture of at least two fluid raw material components is referred to as a reactive mixture.Although the present invention will mainly be described below with regard to the production of polyurethane-based elastomer molded articles by reaction injection molding, other polyurethane-based synthetic resins may be used. (For example, semi-rigid foam) and polyurea resins.

By reaction injection molding using at least two components: a raw material component containing a high molecular weight active hydrogen compound such as a relatively high molecular weight polyol, a chain extender, and optionally a catalyst and a blowing agent, and a raw material component containing a polyisocyanate compound. Methods for producing polyurethane elastomers such as polyurethane elastomers and polyurethaneurea elastomers are known. Typical examples of high molecular weight active hydrogen compounds are relatively high molecular weight polyols, especially polyether polyols.

The chain extender is a relatively low molecular weight polyhydric alcohol or polyamine, which is also a type of active hydrogen-containing compound.

The use of a catalyst is usually essential and is usually added to the active hydrogen compound-containing raw material component, but it can also be added to the incyanate compound-containing raw material component. The use of a small amount of a blowing agent such as a halogenated hydrocarbon blowing agent to produce a microcellular polyurethane elastomer is a commonly used means for improving moldability. The density of the microcellular polyurethane elastomer obtained using this small amount of blowing agent is usually 0.
8g/c■3 or more, especially about 0.9g/c■8 or more. Especially large amounts of reinforcing fibers.

Unless flaky fillers or powder fillers are added, the upper limit is usually 1.2 g/cm' or less, especially about 1.15 g.
/c■1 or less. The density of the non-foamed polyurethane elastomer is also typically within the above range. It is also known to perform reaction injection molding by dividing the active hydrogen-containing compound-containing raw material component into two or more parts and using three or more components in total, including the isocyanate compound-containing raw material component.

[Problem to be solved by the invention] Polyurethane elastomers do not have sufficient heat resistance (
This is a point that requires improvement. In general, the heat resistance of polyurethane elastomers can be improved by: l) increasing the amount of highly polar components such as isocyanate components to increase hardness;

2) Increased hardness by adding filler.

3) A trifunctional or higher functional active hydrogen component or an incyanate component is blended to perform high-order crosslinking.

However, these methods all involve deterioration of elongation properties, and it is extremely difficult to achieve both heat resistance and elongation properties.

Furthermore, it is known that one of the problems in reaction injection molding is that defects such as voids are likely to occur in molded products. A void is a relatively large air bubble that exists inside a molded product. A molded product having such voids has extremely non-uniform physical properties, and also tends to form recesses on the surface, which poses a problem in terms of appearance. Additionally, if voids exist on the surface of the molded product,
The appearance becomes extremely poor due to depressions and missing parts.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems. In a method for producing a synthetic resin molded article by reaction injection molding using at least two components, a raw material component containing a polyisocyanate compound and a polyisocyanate compound, a polyol-based compound (A) having a molecular weight of 400 or less as a chain extender; A combination of aromatic compounds (B) having at least two aminoalkyl groups in the aromatic nucleus,
Alternatively, there is provided a reaction injection molding method characterized in that a combination of these and another chain extender (C) is used.

The first chain extender of the present invention is a polyol compound (A) having a molecular weight of 400 or less. The polyol compound (A) is a compound having two or more alcoholic hydroxyl groups in one molecule, more preferably a compound with a molecular weight of 200 or less, and at least two of the hydroxyl groups are primary hydroxyl groups. It is a compound. In addition, polyol compounds (A
) may be used in combination of two or more. Specific compounds include polyhydric alcohols, poly(or mono)ether polyols, poly(or mono)ester polyols, and the like. For example, ethylene glycol, 1,4-butanediol, diethyl glycol, 1,6-hexanediol, 1,4-bis(hydroxymethyl)cyclohexane, ethylene oxide adducts of polyhydric alcohols, jetanolamine, triethanolalamine, Examples include glycerin and ethylene oxide adducts of polyhydric phenols. Particularly preferred polyol compounds (A) are ethylene glycol and 1,4-butanediol.

The aromatic compound (B) is an aromatic compound having at least two aminoalkyl groups in its aromatic nucleus, and may further have an alkyl group or an electron-withdrawing group in addition to the aminoalkyl group. This compound has a mononuclear, non-fused polynuclear, or fused polynuclear aromatic ring, and in the case of polynuclear, it preferably has two rings, and the aminoalkyl group is bonded to each of the two nuclei. is preferred.

In the case of polynuclear, non-condensed polynuclear having a divalent bonding group such as an alkylene group between two nuclei is preferable.

A particularly preferred aromatic nucleus is a benzene ring. An aminoalkyl group is a group having a primary or secondary amino group and one or more alkylene groups between the amino group and the aromatic nucleus, and is a group represented by >N-R'-, where So, R'
is a linear or branched alkylene group having 1 or more carbon atoms, and particularly preferably an alkylene group having 1 to 4 carbon atoms.

R- is a hydrogen atom or a monovalent organic group, and the monovalent organic group is preferably an alkyl group, a hydroxyalkyl group, or a cyanoalkyl group having 6 or less carbon atoms. However, the most preferred R2 is a hydrogen atom (ie, the amino group of the aminoalkyl group is a primary amino group). Examples of aminoalkyl groups include aminomethyl group, 2-aminoethyl group, 3-aminopropyl group, 2-aminopropyl group, l-amino-1-methylethyl group, and 4-aminobutyl group. A methyl group and a 1-amino-1-methylethyl group are preferred. This aminoalkyl group must be bonded to two or more aromatic nuclei, and in the case of polynuclear groups, it is preferably bonded to different nuclei. The number of aminoalkyl groups is preferably 2 to 3, and 2 is particularly preferred; the aromatic nucleus may also have at least one alkyl group or electron-withdrawing group in addition to the aminoalkyl group ( , the alkyl group has 1 to 1 carbon atoms
8, especially 1 to 4 alkyl groups are suitable. Further, as electron-withdrawing groups, halogen atoms, nitro groups (-NO
□), cyano group (-CN), alkoxycarbonyl group (C
OOR"), N-alkyl substituted carbamoyl group (-CO
N<), s, alkoxysulfonyl group (-SO3R'), and the like are preferred. (R" to R6 are preferably alkyl groups having 1 to 8 carbon atoms, particularly 1 to 4 carbon atoms.) Particularly preferable electron-withdrawing groups are:
They are a chlorine atom, a nitro group, a cyano group, and an alkoxycarbonyl group. The most preferred aromatic compound (B) is bis(aminoalkyl)benzene and its derivatives having at least one alkyl group or electron-withdrawing group, and among these, xylylenediamine is preferred. As the xylylene diamine, meta-xylylene diamine is particularly preferred.

Other chain extenders (C) are the above polyol compounds (A),
It is a chain extender similar to the aromatic compound (B) above, and is a compound having a molecular weight of about 400 or less and having two or more hydroxyl groups and two or more amino groups. Specifically, there are aliphatic polyamines, aromatic polyamines having an amino group bonded to an aromatic nucleus, and monoalkanolamines. This chain extender (C) is 2
Of course, more than one type may be used in combination. This preferred chain extender (C) has at least two amino groups bonded to an aromatic nucleus, and the amino groups are hydrocarbon groups such as alkyl groups or electron-withdrawing groups bonded to the same aromatic nucleus. It is an aromatic polyamine whose reaction activity has been reduced by, for example, As the alkyl group and electron-withdrawing group, those explained in connection with the aromatic compound (B) are preferable. in particular,
For example, JP-A-52-142797 and JP-A-58
Some of these are described in, for example, Japanese Patent No. 32626.

Preferred are diaminobenzene derivatives having at least one alkyl group or electron-withdrawing group, especially diaminobenzene derivatives having alkyl groups in all ortho positions of the amino group (e.g. diethyltolylene simian; usually a mixture of isomers). Yes, the above Japanese Patent Application Publication No. 52-142
797) and monochloro-p(or 0)-di-aminobenzene are preferred.

In the present invention, the ratio of the polyol compound (A) to the total chain extender is preferably 50% by weight or more, particularly 55% by weight or more. The proportion of aromatic compound (B) is 5% by weight.
Above, 10% by weight or more is particularly preferable. The upper limit is 45% by weight. The proportion of other chain extenders (C) is 0 to 40% by weight
, ie not used or at most 40% by weight. More preferably, polyol compound (A)
65% by weight or more, aromatic compound (B) 5 to 35% by weight,
and another chain extender (C) in an amount of 0 to 15% by weight. However, if another chain extender (C) is used,
At least 0.1% by weight is used. Further, the proportion of the aromatic compound (B) to the total of the aromatic compound (B) and other chain extenders (C) is not particularly limited, but is 55% by weight or more, particularly 70% by weight or more. It is preferable that there be.

As the high molecular weight active hydrogen compound, a high molecular weight polyol having two or more hydroxyl groups is suitable. However, the use of high molecular weight active hydrogen compounds having two or more amino groups or an amino group and a hydroxyl group is also known. Oxyalkylene compounds (hereinafter referred to as aminated polyethers) can also be used. The average molecular weight per active hydrogen-containing group (i.e., hydroxyl group and/or amino group) of the high molecular weight active hydrogen compound is about 60
It is preferably between 0 and 4000, particularly between about 800 and 3000. The number of active hydrogen-containing groups per molecule is preferably 2.0 to 4.0 on average, particularly about 2.0 to 3.5. The most preferred high molecular weight active hydrogen compounds are polyether polyols, mixtures of polyether polyols with other high molecular weight polyols, and polymer polyols based on polyether polyols. Polyether polyols obtained by adding monoepoxides such as alkylene oxide, tetrahydrofuran, etc. to ether are suitable, and polyether polyols obtained by adding propylene oxide and/or butylene oxide to polyvalent inishes together with ethylene oxide are particularly preferred. . For reaction injection molding applications, the presence of highly reactive hydroxyl groups, i.e., primary hydroxyl groups, is required, and in the case of polyether polyols using monoepoxides, usually at least about 5% by weight are present at the terminal positions of the polyether chain. The presence of an oxyethylene group is considered almost essential. The higher the proportion of terminal oxyethylene groups, the higher the proportion of primary hydroxyl groups and the higher the reactivity. However, the higher the proportion of oxyethylene groups, the higher the hydrophilicity of the polyether polyol (and thus the lower the polyurethane elastomer. This increases water absorption and causes a decrease in water absorption dimensional properties. Therefore, the upper limit of the amount of oxyethylene groups present in the polyether polyol is appropriately about 35% by weight, and particularly preferably about 25% by weight. However, However, this does not apply when producing hydrophilic polyurethane.It is almost essential that at least 5% by weight of oxyethylene groups exist at the ends of the polyether chains, but it is also present inside the polyether chains. The polyether polyol may be a mixture of two or more polyether polyols having different numbers of hydroxyl groups and molecular weights, and in particular, a mixture of these two or other polyether diols or polyether triols as main components. Mixtures with polyether polyols are preferred.

The polymer polyol is preferably a polyether polyol-based polymer polyol as described above. Particularly preferred are polymer polyols obtained by polymerizing at least one of acrylonitrile, styrene, and other monomers in a polyether polyol. others,
Polymer polyols obtained by polymerizing vinyl monomers in polyether polyols containing unsaturated groups, polyols containing condensation polymers obtained by condensation polymerization in polyether polyols, and polyols containing other polymer components can also be used. . Other high molecular weight polyols that can be used with polyether polyols include hydroxyl group-containing hydrocarbon polymers such as homopolymers and copolymers of butadiene having two or more hydroxyl groups, and polyester polyols. The combined use of is effective in improving the water absorption dimensional properties of polyurethane elastomers. The aminated polyether is a compound obtained by aminating some or all of the hydroxyl groups of the above polyether polyol or polyether polyol that does not have an oxyethylene group at the end, and can be used alone or as a polyether. Can be used in combination with polyol, etc.

The amount of chain extender relative to the total of high molecular weight active hydrogen compound and chain extender should be at least 3% by weight. A large amount of chain extender (certainly a hard molded product can be obtained (if the high molecular weight active hydrogen compound is the same).In order to obtain a molded product with good heat resistance, a large amount of chain extender is used. Hard molded articles are preferred.In the present invention, the amount of chain extender is between 5 and 50
% by weight is preferred, in particular 10-45% by weight, and in order to obtain particularly hard molded products, 20-45% by weight is used.

Modified or unmodified aromatic polyisocyanates are suitable as the polyisocyanate compound, and in some cases, other polyisocyanate compounds may be used alone or in combination with aromatic polyisocyanates and the like. As the aromatic polyisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate, tolylene diisocyanate, etc. are suitable, and diphenylmethane diisocyanate consisting of 4,4'-diphenylmethane diisocyanate and its isomers is particularly suitable. These can be used as unmodified products, but modified products are generally used when applied to reaction injection molding methods. Modified products include, but are not limited to, prepolymer-type modified products and carbodiimide-type modified products. The amount of the polyisocyanate compound used is preferably about 90 to 120, particularly about 95 to 110, expressed as an isocyanate index.

The use of catalysts is usually essential in the production of polyurethane elastomers. As a catalyst, a tertiary amine catalyst or an organic tin compound is usually used, and a blowing agent is often used to improve the filling properties of the reactive mixture into a mold. Polyurethane elastomers obtained using relatively small amounts of blowing agents are microcellular (
It is called a polyurethane-based elastomer. Examples of blowing agents include trichlorofluoroethane, methylene chloride, other halogenated hydrocarbon blowing agents, and water, and both are often used in combination. It is particularly preferable to use a halogenated hydrocarbon blowing agent, and the amount thereof is preferably about 15 parts by weight or less, particularly about 2 to 10 parts by weight, based on 100 parts by weight of the high molecular weight active hydrogen compound.

Polyurethane elastomers are produced by using arbitrary additives in addition to the above raw materials. Optional additives include fillers, colorants, ultraviolet absorbers,
These include light stabilizers, antioxidants, and flame retardants. Examples of fillers include inorganic fibers such as glass fiber and wollastonite, organic fibers such as synthetic fibers, calcium carbonate, other powder fillers, mica, and other flat fillers. The amount of these fillers to be filled is preferably about 30% by weight or less, particularly 20% by weight or less, based on the total synthetic resin raw material, since problems arise with the viscosity and operability of the raw material components as the amount increases. These additives are mainly blended into the active hydrogen compound-containing raw material component, but those that are non-reactive with isocyanate groups can also be blended into the isocyanate compound-containing raw material component.

Synthetic resin molded articles obtained by the present invention, particularly polyurethane elastomer molded articles, can be used for various purposes.

It is particularly suitable for automobile exterior parts, such as bumper shells, fascias, fenders, and door panels. However, the application is not limited to this (it can also be used in other automotive parts, electronic or electronic device housings, and other applications).

EXAMPLES The present invention will be specifically explained below using Examples, but the present invention is not limited to these Examples.

Examples The examples described below were conducted using the following raw material components and molding tests.

l) High molecular weight polyol A: Oxyethylene group content 20% by weight with an oxyethylene group at the end, hydroxyl value 28 using glycerin as an initiator
A mixture of equal weights of polyoxypropylene oxyethylene triol and polyoxypropylene oxyethylene diol having an oxyethylene group at the terminal and having an oxyethylene group content of 20% by weight and a hydroxyl value of 28 using dipropylene glycol as an initiator.

2) Isocyanate B Prepolymer type modified diphenylmethane with an isocyanate content of 26.0% by weight. The amount of diisocyanate component to be used is such that the equivalent ratio is 1.05 to the active hydrogen component.

Note that the above usage amount "parts" refers to parts by weight.

(Tensile test) 50% modulus (kg/cm"), tensile strength (kg/cm")
cm 2 ) and elongation (%) were measured using No. 2 dumbbells and a tensile speed of 250 mm/min.

(Heat sag (heat sag)) A 25 x 125 x 3 mm sample was left at 120°C for 1 hour with a 100 mm overhang.
After cooling for 30 minutes at room temperature, the sagging distance was measured.

(Molding test) Using a reaction injection molding device (high pressure foaming machine), the discharge output was 15
Reaction injection molding was carried out by adjusting the liquid temperature of each component to 30 to 40° C. and a discharge rate of 15±5 kg/min.

The mold cavity had a size of 80 mm x 350 mm, a wall thickness of 10 mm, and a temperature adjusted to 60 to 70 °C. It was used for moldability evaluation.
The size is 3 mm, the wall thickness is 3 mm, and the temperature is 60 to 70.
The temperature adjusted to ℃ was used for evaluation of physical property values.

Example 1 84 parts of high molecular weight polyol A and 13 parts of ethylene glycol
3.0 parts of meta-xylene diamine was added to the mixture and mixed and stirred. Furthermore, 0.25 part of triethylenediamine and 0.05 part of dibutyltin dilaurate were added to form an active hydrogen component. The equivalent ratio of isocyanate B to this active hydrogen component is 1.
Molding was performed using an amount of 0.05 to obtain a molded product. The molded product has a 50% tensile modulus of 150 kg/cm",
The tensile strength was 332 kg/cm", the elongation was 289%, and the heat sag was 17 mm. Also, there were few voids in the molded product.

Example 2 84 parts of high molecular weight polyol A and 13 parts of ethylene glycol
3.0 parts of metaxylene diamine and 0.3 parts of diethyltolylene diamine were added to the mixture and mixed and stirred. Furthermore, 0.25 parts of triethylenediamine, 0 part of dibutyltin dilaurate
．． 05 parts were added to form an active hydrogen component. Molding was carried out using isocyanate B in an equivalent ratio of 1.05 to the active hydrogen component to obtain a molded product. The molded product has a 50% tensile modulus of 150 kg/cm" and a tensile strength of 366.
kg/cm", elongation of 300%, and heat sag of 14 mm. Also, there were very few voids in the molded product.

Example 3 84 parts of high molecular weight polyol A and 13 parts of ethylene glycol
3.0 parts of metaxylene diamine, 0-chloro-p-
0.1 part of phenylenediamine was added and mixed and stirred. Furthermore, 0.25 part of triethylenediamine and 0.05 part of dibutyltin dilaurate were added to form an active hydrogen component. Molding was carried out using the active hydrogen component and Iwashyanate B in an amount such that the equivalent ratio was 1.05 to obtain a molded product. The molded product has a 50% tensile modulus of 153 kg/cm, a tensile strength of 431 kg/cm, an elongation of 320%, and a heat sag of 17.
It was mm. Furthermore, there were very few voids in the molded product.

Comparative Example 1 84 parts of high molecular weight polyol A and 13 parts of ethylene glycol
1 part and mixed and stirred. Furthermore, 0.25 part of triethylenediamine and 0.05 part of dibutyltin dilaurate were added to form an active hydrogen component. Molding was carried out using isocyanate B in an equivalent ratio of 1.05 to the active hydrogen component to obtain a molded product.

The molded product has a 50% tensile modulus of 143 kg/cm'
The molded product had a tensile strength of 248 kg/cm" and an elongation of 245%. Also, a large amount of voids were generated in the molded product.

Claims (1)

[Scope of Claims] 1. Using at least two components: a raw material component containing a high molecular weight active hydrogen compound and a chain extender and optionally containing a catalyst and a blowing agent, and a raw material component containing a polyisocyanate compound, In a method for producing a synthetic resin molded article by reaction injection molding, a combination of a polyol compound (A) with a molecular weight of 400 or less and an aromatic compound (B) having at least two aminoalkyl groups in the aromatic nucleus as a chain extender. , or a combination thereof with another chain extender (C). 2. The method according to claim 1, wherein the aromatic compound (B) is a benzene derivative having two aminoalkyl groups having 1 to 4 carbon atoms. 3. The method according to claim 1, wherein the other chain extender (C) is a diaminobenzene derivative having a substituent that reduces the reaction activity of the amino group. 4. Polyol compound (A) relative to the total chain extender
50% by weight or more, aromatic compound (B) 5 to 45% by weight,
The method according to claim 1, comprising a combination of 0 to 40% by weight of other chain extenders (C). 5. The proportion of the polyol compound (A) is 65% by weight or more, the aromatic compound (B) is 5 to 35% by weight, and other chain extenders (
C) 0 to 15% by weight of the combination.