JPS59191712A - Reaction injection molding - Google Patents

Abstract

PURPOSE:To obtain a molding, such as a car trim, excellent in water resistance, by effecting the reaction injection molding of a material comprising a specified high-MW active hydrogen compound, a chain extender and a polyisocyanate compound in the presence of a specified catalyst. CONSTITUTION:In producing a polyurethane elastomer molding by effecting the reaction injection molding of a material consisting essentially of a high-MW active hydrogen compound, a chain extender and a polyisocyanate compound in the presence of a catalyst; said high-MW active hydrogen compound comprises a mixture of an aminated polyether derived by aminating the hydroxyl groups of a polyetherpolyol and having an average MW per functional group of about 500-4,000 and a different high-MW active hydrogen compound, said active hydrogen compound having an average degree of amination of 5-70%, an average functionality >=2.0, and an average MW per functional group of about 500- 4,000, and said catalyst does not contain an effective amount of a tert. amine catalyst. This molding has a low dimensional change on obsorption of water and is suitable as a car bumper shell, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for molding a polyurethaneurea elastomer molded article by a reaction injection molding method,
In particular, it relates to reactive injection molding methods using specific active hydrogen compounds and catalysts.

Methods for producing molded articles of polyurethane, polyurethane urea, and other synthetic resins by reaction injection molding are known. Reaction injection molding is a method in which at least two components that react rapidly when mixed with each other are rapidly mixed by impingement mixing, the mixture is filled into a mold, and the mixture is reacted and cured. The two mutually reactive components are usually liquids, but may also be slurry-like liquids containing insoluble components such as fillers.

Polyurethane, polyurethane urea, etc. are components in which one component is primarily a polyisocyanate compound, and the other component is primarily an active hydrogen compound having at least two active hydrogen-containing groups. Obtained using at least two components. Hereinafter, in the present invention, an active hydrogen-containing group refers to a functional group containing active hydrogen that can react with an isocyanate group, and representative examples thereof are a hydroxyl group and an amino group.

In reaction injection molding, non-foamed elastomers and microcellular elastomers (hereinafter both referred to as elastomers) such as polyurethane and polyurethane urea are usually made by combining active hydrogen compounds with high molecular weight polyols and low molecular weight polyols or polyamines into polyisocyanate compounds. It is obtained by reacting with Low molecular weight polyols and polyamines are sometimes called crosslinking agents (especially in the case of trifunctional or higher functional compounds), but in the present invention, bifunctional and trifunctional or higher functional compounds are also referred to as chain extenders. In addition, the polyurethaneurea elastomer in the present invention, including the microcellular elastomer, has a density of about 0.85.
17 cm3 or more, especially 0.95'/cm3 or more,
If no filler is included, the upper limit is approximately 1.2 t 7c
m3, specifically about 1.15 f/1wr”.

This microcellular elastomer is usually obtained using small amounts of blowing agents. The amount of blowing agent used is usually about 15 parts by weight or less per 100 parts by weight of the high molecular weight active hydrogen compound.
In particular, it is 10 parts by weight or less. Furthermore, the difference between microcellular elastomers and ordinary flexible polyurethane foam lies in the difference in expansion ratio, and the expansion ratio of microcellular elastomers is usually 2 or less.

One of the characteristics of the raw material required in reaction injection molding is that the raw material is a highly reactive raw material. If a raw material with low reactivity is used, it will not be possible to achieve the high molding speed that is a characteristic of reaction injection molding. The reactivity of the raw material mainly depends on the proportion of primary hydroxyl groups in the high molecular weight polyol, and the higher the proportion of primary hydroxyl groups, the higher the reactivity. The hydroxyl group of polyether polyol, which is a commonly used high molecular weight polyol, is primary when the oxyalkylene group to which it is bonded is an oxyethylene group, and usually secondary when it is another oxyalkylene group. Therefore, a polyether polyol with a high proportion of primary hydroxyl groups necessarily becomes a polyether polyol with a high proportion of oxyethylene groups. However, it has been found that the use of polyether polyols with a high content of oxyethylene groups has an unfavorable effect on the physical properties of the resulting synthetic resin. For example, oxyethylene groups are hydrophilic whereas other oxyalkylene groups are hydrophobic. Therefore, synthetic resins obtained using polyether polyols with a high content of oxyethylene groups have high water absorption properties, and in particular, dimensional changes due to water absorption are large. Furthermore, although the reason for this is not very clear, it has high embrittlement at low temperatures, which is particularly likely to cause problems for products that are often used at low temperatures. Although the use of polyether polyols with a high content of oxyethylene groups is problematic, in order to maintain the high reactivity required in reaction injection molding, it is necessary to use polyether polyols with a high content of oxyethylene groups. There were many things I didn't get.

In order to solve the above-mentioned problems, the present inventors previously conducted an investigation to find a polyether polyol with a low oxyethylene group content and high reactivity, and as a result, aminated some or all of the hydroxyl groups of the polyether polyol. It was discovered that polyether compounds obtained by
-120601). The amino group has an activity equal to or higher than that of the primary hydroxyl group, and the oxyalkylene group to which the amino group is bonded need not be an oxyethylene group. Therefore, oxyethylene groups are not essential in aminated polyols, and therefore, by using aminated polyethers that are free of oxyethylene groups or have a low oxyethylene fund fit, all of the above problems are solved. On the other hand, two new findings were obtained in reaction injection molding using aminated polyether.

This is a feature in the use of aminated polyols that is different from the problem of oxyethylene groups mentioned above. One of these is that the thermal sagging properties of the resulting synthetic resin are improved over those obtained using polyether polyols. Heat sag is one measure of heat resistance; the lower the heat sag, the better the heat resistance. The thermal sag test is performed by placing a horizontally held specimen in a heated atmosphere for a certain period of time and measuring its sag (downward deflection). The second characteristic is that when aminated polyethers are used, the pattern of reaction progression of reactive mixtures (i.e., mixtures obtained by mixing at least two components that are reactive with each other) is more pronounced than when using polyether polyols. This makes it suitable for reaction injection molding. In reaction injection molding, reactive mixtures react rapidly to form synthetic resins. As the reaction progresses, the viscosity of the reactive mixture increases rapidly. However, it is preferred that the reactive mixture has a low viscosity until it is filled into a mold. Otherwise, defects that are likely to occur when a mold is filled with a highly viscous reactive mixture, such as unfilled areas, uneven physical properties of the molded product, and poor appearance, will occur. Conversely, if a reactive mixture with sufficiently low viscosity is used until it is filled into a mold, the subsequent reaction will be slow and the molding time will be extended. This problem is particularly likely to occur in the case of large molded products or molded products with shapes that are difficult to fill (for example, molded products with large area and thin thickness). Therefore, the ideal reaction pattern for a reactive mixture in reaction injection molding is one in which the initial reaction is slow and then the reaction progresses rapidly.

The present inventor conducted a detailed study on molded products of polyurethaneurea elastomer obtained by reaction injection molding using the above-mentioned aminated polyether. Particularly recently, there has been a strong demand for reducing the rate of water absorption dimensional change in automobile bumper outer shells made of polyurethane elastomers obtained by reaction injection molding, and we reexamined the problem of water absorption in the polyurethane urea elastomers. In the above invention, by using an aminated polyether with a low oxyethylene group content or a mixture thereof with a polyether polyol, the water absorption of the polyurethane urea elastomer is certainly reduced, and the polyurethane urea elastomer has a low dimensional change rate after water absorption. Although a urea elastomer can be obtained, it has been found that there are various problems in further reducing water absorption. When using an aminated polyether or a mixture thereof with a polyether polyol, it is necessary to increase the overall amination rate (details will be described later) in order to further reduce the content of oxyethylene groups. That is, if the amination rate is low, the activity of the remaining hydroxyl groups becomes a problem, and in order to convert these hydroxyl groups into highly active primary hydroxyl groups, it is necessary to increase the oxyethylene group content.

However, increasing the amination rate makes it difficult to control the reaction, and in order to make the normal reaction injection molding method suitable, the amination rate of aminated polyethers and mixtures of them and polyether polyols must be 70% or less, especially 5
5 inches or less is preferable.

On the other hand, aminated polyethers are more expensive than corresponding polyether polyols, and from the economic point of view, a lower amination rate is preferable.

The present inventor was considering a method for reducing the water absorption dimensional change rate without extremely increasing the amination rate, and unexpectedly found that the amount of the 6th-class amine catalyst used was related to the water absorption dimensional change rate. I discovered what I was doing. That is, it has been found that the smaller the amount of the tertiary amine catalyst used, the more significantly the water absorption dimensional change rate decreases. The effect of the tertiary amine catalyst on the water absorption of reaction injection molded urethane is manifested in an increase in the weight change rate of water absorption in systems using ordinary polyoxyalkylene polyethers, but does not have much effect on the water absorption dimensional change rate. However, the present invention has revealed that in systems using aminated polyethers, the influence of the tertiary amine catalyst is significant not only on the water absorption weight change rate but also on the water absorption dimensional change rate. The reason for this is completely unknown, but the action of the catalyst influences the structure of the polyurethaneurea elastomer, and the action of the tertiary amine catalyst gives the polyurethaneurea elastomer some kind of structure that increases the water absorption dimensional change rate. It is expected that there will be.

In the reaction injection molding of polyurethane elastomers and polyurethaneurea elastomers, tertiary amine catalysts have conventionally been commonly used. However, the present inventor has discovered that a good polyurethaneurea-based elastomer can be obtained by reaction injection molding without substantially using a tertiary amine-based catalyst.

The gist of the present invention is to produce a polyurethaneurea elastomer molded article by reacting a high molecular weight active hydrogen compound, a chain extender, and a polyisocyanate compound as essential raw materials in the presence of a catalyst. In the reaction injection molding method, the average molecular weight per functional group obtained by aminating some or all of the hydroxyl groups of a polyether polyol with a high molecular weight active hydrogen compound is about 500 to 4.
000 aminated polyether, or a mixture of the aminated polyether and at least one other high molecular weight active hydrogen compound, the average amination rate of the high molecular weight active hydrogen compound is 5 to 70%, and the average functional The number of groups is 2.0 or more, and the average molecular weight per functional group is about 500 to 4000.
and the catalyst does not substantially contain an effective amount of a tertiary amine catalyst.

In reaction injection molding of polyurethane elastomers and polyurethaneurea elastomers, triethylenediamine is a commonly used tertiary amine catalyst. Triethylenediamine is usually used as a solution in a polyhydric alcohol such as dipropylene glycol.

For example, the product name [Dabco 33LVJ, which is a typical triethylenediamine solution, contains 36% of triethylenediamine.
Dibropine glycol solution containing weight ratio. In addition, examples of tertiary amine catalysts include triethylamine, N-ethelmorpholine, N,N-dimethylethanolamine, N-ethelpiperidine, N, N, N,
' r-Tetramethylethylenediamine and the like. The substantially effective amount of tertiary amine catalyst depends on its catalytic activity. For example, the effective amount of a highly active catalyst, such as triethylene diamine, is small), and the effective amount of a less active catalyst, such as N-ethermorpholine, is much larger.

Therefore, in the present invention, when the tertiary amine catalyst is triethylenediamine, the upper limit of the amount used is very small, for example, 1/100 part by weight or less, especially 115 oo It is preferable that it is not more than parts by weight. On the other hand, in the case of a tertiary amine catalyst with low activity, the upper limit of its usage is larger than that of triethylenediamine. Of course, these third
Needless to say, it is most preferable that substantially no class amine catalyst be used.

Those that can be used as effective catalysts in the present invention are metal compounds, especially organometallic compounds. Examples of the metal component include tin, lead, zinc, iron, cobalt, antimony, and bismuth, with tin or lead being particularly preferred, and tin being particularly preferred. Particularly preferred organometallic compound catalysts include dibutyltin dilaurate, diptyltin diacetate, dimethyltin dilaurate, stannous octoate, other tin salts of carboxylic acids, and lead octoate, lead oleate, lead naphthenate, and others. It is a lead salt of carboxylic acid. These catalysts can be used in combination, and can also be used in combination with other catalysts. The amount used is not particularly limited, but 0.00 parts by weight per 10Q parts by weight of the high molecular weight active hydrogen compound.
0.01 to 1 part by weight is suitable.

The high molecular weight active hydrogen compound is essentially an aminated polyether described below, but may also be a combination of an aminated polyether and another high molecular weight active hydrogen compound. As other high molecular weight active hydrogen compounds, polyether polyols are most preferred (aminated polyethers with a low amination rate are considered to be substantially a mixture of aminated polyethers and polyether polyols).

Additionally, relatively small amounts (usually up to about 60% by weight) of other high molecular weight polyols may be added to the aminated polyether or mixture thereof and polyether polyol. Typical examples of other high molecular weight polyols are hydrocarbon polymers having two or more hydroxyl groups, such as polybutadiene glycols. In addition, other high molecular weight polyols such as polyester polyols may also be used in combination.

These high molecular weight active hydrogen compounds will be explained below.

First, aminated polyether will be explained. Methods for producing aminated polyethers and the use thereof to produce foam synthetic resins such as polyurethane urea foam are known, for example, as disclosed in Japanese Patent Publication No. 11685-1985, Japanese Patent Publication No. 28914-1972, Japanese Patent Publication No. 28914-1987, 51-4
It is described in Japanese Patent Application Laid-open No. 8799, Japanese Patent Application Laid-open No. 50-29699, etc. Aminated polyether can usually be represented by the following general formula (1).

x: (m+n)-valent initiator residue R: alkylene group m: an integer of 1 or more n: an integer of 0 or 1 or more, where m+n is 2 or more p, q: 1/(m-4-n) of the molecular weight is about 500 to 40
The integer A, which is 00, is an initiator residue, such as water, polyhydric alcohol,
It is a residue obtained by removing a hydrogen atom from a polyhydric phenol, alkanolamine, mono- or polyamine, or other initiator (details will be described later) with which a cyclic ether reacts.

÷RO+ and +RO+ are different oxiaps
q It may be a random or block polymer of alkylene groups, and when m or n is 2 or more, p or q in each may be different. This aminated polyol is usually A(g-(Ro), uoH,
), , [x is an integer including p+q] is obtained by aminating a polyether polyol with ammonia, but the method is not limited to this method. Regarding the amination of polyether polyols, for example, the above-mentioned Japanese Patent Publication No. 48-11685, Japanese Patent Publication No. 51-4879, etc.
In addition to Publication No. 9, for example, Japanese Patent Publication No. 45-7553,
Special Publication No. 45-16443, Special Publication No. 49-1415
It is also described in Publication No. 8 and Japanese Patent Publication No. 49-14159. In the present invention, the aminated polyether may be a compound represented by the above general formula (1) that does not necessarily explode. For example, this applies when part or all of the cyclic ethers are cyclic ethers other than alkylene oxide, such as halogenated alkylene oxide, styrene oxide, or glycidyl ether. In short, the aminated polyether in the present invention is a compound in which part or all of the terminal OH groups of a polyether polyol are replaced with NH2 groups, and is not limited to the compound represented by the above general formula (1). However, it goes without saying that the compound represented by the above general formula (1) is a typical example of aminated polyether and is the most suitable compound in the present invention.

In the present invention, the molecular weight of the aminated polyether is on average about 500 to 4000 per active hydrogen-containing group. The active hydrogen-containing group in the aminated polyether is an amino group or an amino group and a hydroxyl group. That is, the above general formula (1)
In the aminated polyether represented by , the molecular weight divided by (m+n) is about 500 to 4,000. A more preferred average molecular weight per active hydrogen-containing group is about 1000 to 300 degrees. In the aminated polyether of general formula (1), the amination rate can be expressed as =X100. The amination rate refers to the ratio of terminal amino groups to the total number of terminal amino groups and terminal hydroxyl groups, and the amination rate of the entire aminated polyether is the average of the amination rates of one molecule of aminated polyether. Therefore, the entire aminated polyether may contain non-aminated polyether polyol molecules. Therefore, as described below, aminated polyethers and polyether polyols may be used in combination in the present invention. The amination rate of the aminated polyether itself is 5 to 1
00%, preferably 20~
95 inches, more preferably 20 to 60 inches. Also,
When only aminated polyether is used as the high molecular weight active hydrogen compound, it is necessary that the average amination rate is as described below.

It is known that polyurethane urea elastomers and microcellular elastomers can be molded by reaction injection molding using a low molecular weight aminated polyether as a chain extender, and is described in JP-A-56-109216. .

There, it is described that a high molecular weight polyether polyol, an aminated polyether with a molecular weight of about 500 or less, and a low molecular weight polyol are used as active hydrogen compound components to react with a polyisocyanate compound to mold a synthetic resin by reaction injection molding. ing. This low molecular weight aminated polyether is used as a chain extender and has a molecular weight of at least 1000 (per active hydrogen-containing group) whereas the aminated polyether of the present invention has a molecular weight of at least 1000.
0 and at least two active hydrogen-containing groups), it has a much lower molecular weight. The use of low molecular weight aminated polyethers is not effective in solving the above problems. That is, it is necessary to use a primary hydroxyl group-containing polyether polyol with a high content of oxyethylene groups as the high molecular weight polyether polyol. Furthermore, a reaction pattern suitable for the reaction injection molding described above cannot be obtained.

This is a characteristic characteristic of high molecular weight aminated polyethers.

The polyether polyol that is a raw material for the aminated polyether and the high molecular weight polyol such as the polyether polyol that can be used in combination with the aminated polyether are preferably polyether polyols obtained by adding cyclic ethers to an initiator. As described above, the initiator includes water, polyhydric alcohol, polyhydric phenol, alkanolamine, mono- or polyamine, and other compounds. Since water reacts with cyclic ethers to produce diols, the diols can be considered as initiators. The number of functional groups in the initiator is preferably 2 or more, particularly 2 to 8, and more preferably 2 to 4. Two or more initiators can be used in combination. Representative examples of initiators are shown below, but are not limited to these.

Polyhydric alcohols: ethylene glycol, fluoropylene glycol, diethylene glycol.

Chrycerin, trimethylolpropane.

Hexanetriol, diglycerin, pentaerythritol, methyl glycoside.

Dextrose, sorbitol, sucrose.

Polyhydric phenol = phenol-aldehyde initial condensation product,
Bisphenol A, bisphenol F.

Alkanolamine: Monoethanolamine.

Mono- or polyamines: aniline, diaminodiphenylmethane) IJ diamine.

Ethylenediamine.

The cyclic ethers added to the initiator are preferably compounds containing a 3- to 6-membered oxygen-containing ring, such as epoxides containing epoxy resins. As the alkylene oxide, particularly preferred are epoxides having 2 to 4 carbon atoms, such as ethylene oxide, propylene oxide, butylene oxide, etc., especially propylene oxide and/or butylene oxide, or a combination thereof with ethylene oxide. Other epoxides include halogenated alkylene oxides such as epichlorohydrin;
Compounds having epoxy groups such as styrene oxide, various glycidyl ethers and esters, and epoxy resins can be used. When two or more types of epoxides are used in combination, they can be mixed and reacted, or they can be reacted sequentially. For example, a combination of propylene oxide and ethylene oxide can be used to produce a polyoxyalkylene chain in which oxypropylene groups and toxyethylene groups are randomly and/or randomly polymerized in blocks. In particular, the oxyethylene group is preferably present at the terminal portion of the oxyalkylene chain. Preferred cyclic ethers other than epoxides are tetrahydrofuran, and its polymer poly(oxytetramethylene) glycol is a preferred polyether polyol in the present invention.

The polyether polyol may be a mixture of two or more polyether polyols. The average molecular weight per hydroxyl group is preferably about 500 to 4,000, particularly preferably about 1,000 to 3,000. Even if the hydroxyl group of a polyether polyol is replaced with an amino group, the change in its molecular weight can theoretically be ignored. It can be used as a polyether polyol in combination with polyethers. By aminating this polyether polyol with ammonia or the like as in the above-mentioned known example, the relatively high molecular weight aminated polyether of the present invention can be produced. On the other hand, polyether polyols that can be used in combination with this aminated polyether include polyether polyols of the same or different type, or of the same or different molecular weight as the polyether polyol that is the raw material for the aminated polyether. can be used. Combining an aminated polyether and a polyether polyol is advantageous from various aspects. For example, by combining an aminated polyether with a polyether polyol having a different molecular weight or a different number of functional groups, it is easy to vary the physical properties of the resulting synthetic resin depending on the purpose. This combination is also advantageous from the viewpoint of adjusting the reactivity and economic efficiency.

The aminated polyethers and polyether polyols may also contain up to 40 parts by weight of polymeric components.

Polymer components include acrylonitrile, styrene, and methacrylate trile.

Methyl methacrylate, butyl acrylate.

Single or copolymers of isopsin and other vinyl monomers are suitable. This polymer component-containing polyether polyol is usually called a polymer polyol.
It is usually obtained by polymerizing a vinyl monomer in a polyether polyol, and is a composition in which fine polymer particles are stably dispersed in the polyether polyol.

A typical example of another high-volume active hydrogen compound that can be used in combination with the aminated polyether is a hydrocarbon polymer having two or more hydroxyl groups. Particularly preferred is a combination of an aminated polyether and a hydroxyl group-containing hydrocarbon polymer, or a combination of an aminated polyether, a polyether polyol, and a hydroxyl group-containing hydrocarbon polymer.

The amount of the hydroxyl group-containing hydrocarbon polymer to be used is preferably about 30 parts by weight or less, particularly about 20 parts by weight or less, based on the total high molecular weight active hydrogen compound. Examples of hydroxyl group-containing hydrocarbon polymers include hydroxyl group-containing polybutadiene and polybutadiene copolymers (for example, copolymers of butadiene and acrylonitrile, styrene, and other monomers).
．． Also preferred are compounds obtained by adding a small amount of ethylene oxide, propylene oxide, or other alkylene oxide to these hydroxyl group-containing hydrocarbon polymers.

The molecular weight is suitably about 500 to 4,000 per hydroxyl group, but is not limited to this. These hydroxyl group-containing hydrocarbon polymers have high hydrophobicity and are effective in reducing the water absorption of polyurethaneurea elastomers, and their use makes it possible to obtain polyurethaneurea elastomers with even lower water absorption dimensional change rates. Furthermore, other high molecular weight active hydrogen compounds that can be used in combination include polyester polyols and polyether ester polyols. Of course, two or more of these high molecular weight active hydrogen compounds can be used in combination, as in the case of aminated polyethers and polyether polyols.

The high molecular weight active hydrogen compound that essentially includes aminated polyether in the present invention may be aminated polyether alone or a mixture of it and other high molecular weight active hydrogen compounds, especially polyether polyols, The average amination rate per molecule is 5 to 70, the number of functional groups (that is, both amino groups and hydroxyl groups) is 2.0 or more, and the molecular weight per functional group is about 500 to 4,000. is necessary. Therefore, each component does not need to be within this numerical range; for example, an aminated polyether with an amination ratio of over 70 and a polyether polyol can be mixed to have an amination ratio of 5 to 70. More preferably, the average amination rate is 10-70%, especially 20-55%, the average number of functional groups is 2.0-4.0, and the average molecular weight per functional group is about 1000-3000. The average oxyethylene group content in a high molecular weight active hydrogen compound can vary depending on the desired degree of water absorption dimensional change rate and its composition.

When using polybutadiene glycol or fillers described below, the water absorption dimensional change rate becomes low even if the oxyethylene group content is relatively high. Usually, the average content of oxyethylene groups is suitably less than 35 parts per weight, particularly less than 20 parts per weight. In particular, in order to reduce the water absorption dimensional change rate, the weight coefficient can be set to 15% by weight or less.

The chain extender consists of a low molecular weight polyol and/or a polyamine compound having a molecular weight of 400 or less. Especially molecular weight 20
Low molecular weight polyols of 0 or less are preferred. Suitable low molecular weight polyols include polyhydric alcohols and alkanolamines having 2 or more, especially 2 to 4, hydroxyl groups, and polyols obtained by adding a small amount of alkylene oxide to the above-mentioned polyvalent initiator.

Particularly preferred low molecular weight polyols are dihydric alcohols having 2 to 4 carbon atoms. Suitable polyamines are aromatic diamines having an alkyl substituent and /i a halogen. Preferred specific chain extenders include ethylene glycol, 1°4-butanediol, propylene glycol, diethylene glycol, cyglobylene glycol,
Examples include glycerin, trimethylolpropane, jetanolamine, and triethanolamine, with ethylene glycol and 1,4-butanediol being particularly preferred. The amount used is 5 to 50% of the total amount with the high molecular weight active hydrogen compound.
40% by weight, especially 10 to 30% by weight is suitable.

It has been found that the use of a chain extender having an oxyethylene group such as ethylene glycol does not have any adverse effect on the water absorption dimensional change of the polyurethaneurea elastomer.

The reason for this is that the chain extender reacts with the polyisocyanate compound to form a hard block of the polyurethaneurea elastomer, and this nord block has low water absorption even if oxyethylene groups are present therein. It is thought that even if water is absorbed, it will not cause deformation because it is hard. On the other hand, the oxyethylene group present at the end of the molecular chain of the high molecular weight active hydrogen compound is thought to exist adjacent to this hard block, but unlike the case where it is within the hard block, this part belonging to the soft block The presence of oxyethylene groups in is considered to have a large influence on the water absorption dimensional change.

The polyisocyanate compound includes aromatic, alicyclic, aliphatic, and other polyisocyanate compounds having at least two isocyanate groups, and modified products thereof. For example, 2,4-1-lylene diisocyanate, 2,6-tolylene diisonanate, 4,4'-diphenylmethane diisocyanate, polymethylene polyphenylisocyanate, xylylene diisocyanate, isophorone diisocyanate, methylene-bis(cyclohexyl isocyanate), Examples include hexamethylene diisocyanate. Examples of modified products include dimers, trimers, prepolymer modified products, carbodiimide modified products, urea modified products, and others. These polyisocyanate compounds are 2
More than one species may be used in combination. Particularly preferred polyisocyanate compounds are 4,4'-diphenylmethane diisocyanate, and its carbodiimide-modified and prepolymer-type modified products. The amount of the polyisocyanate compound used is preferably 90 to 120, particularly 95 to 110, expressed as an isocyanate index.

In the production of a polyurethaneurea elastomer using a reaction injection molding method, it is preferable to use a blowing agent in addition to the catalyst. In the present invention, a blowing agent is not necessarily essential, and an elastomer that is slightly foamed due to the presence of air and water dissolved in the raw material can be obtained without using a blowing agent.
Moreover, by sufficiently removing these, a non-foamed elastomer can be obtained. However, it is preferable to use a small amount of blowing agent for reasons such as improving moldability. As the blowing agent, air, water, etc. can be used, but it is preferable to use a low-boiling-point -lokenized hydrocarbon.

Specifically, trichlorofluoromethane, dichlorodifluoromethane, methylene chloride, etc. are suitable. The amount thereof is preferably 15 parts by weight or less, particularly 2 to 10 parts by weight, based on 100 parts by weight of the high molecular weight active hydrogen compound and chain extender.

Furthermore, various additives may be added as optional additive components. Examples include fibrous, flat, and powder fillers, colorants, ultraviolet absorbers, antioxidants, flame retardants, and internal mold release agents. In particular, blending a fibrous filler has the effect of reducing the rate of dimensional change after water absorption. This seems to be to improve the rigidity and strength of the polyurethaneurea elastomer. Suitable fibrous fillers include milled glass fibers, cut fibers, and wollastonite. The amount should be about 30% by weight or less, especially 20% by weight based on the entire polyurethane urea elastomer.
It is sufficiently effective below the weight ratio. These additives, including the catalysts and blowing agents mentioned above, are usually added to the polyol component containing the high molecular weight active hydrogen compound and the chain extender. However, additives which are inert toward inocyanate groups can also be added to the isocyanate component.

The reaction injection molding method usually involves rapidly mixing the above-mentioned high molecular weight active hydrogen compound, an active hydrogen component containing a chain extender, and an incyanate component, and immediately injecting the mixture into a mold, allowing the mixture to react in the mold, and after curing. This is done by taking it out as a molded product. In some cases, three or more components may be used by dividing the active hydrogen component or incyanate component into two or more, or by using a third component. Rapid mixing is usually achieved by impingement mixing of each component, and an after-mixing mechanism may be provided in a portion of the runner to perform remixing. The present invention is used for molding exterior parts of automobiles, especially bumper shells. Also, fender
It is also suitable for molding fascia door panels, front panels, and other automotive exterior parts. However, the present invention is not limited to these uses, but can also be applied to other molded products that require water resistance.

The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Examples and Comparative Examples A mixture of a high molecular weight active hydrogen compound, a chain extender, etc. listed in Table 3 below was charged into a tank on the polyether component side of a high-pressure foaming machine, and a polyisocyanate compound was charged into a tank on the isocyanate component side. The discharge pressure of the high pressure foaming machine is 15
Reaction injection molding was carried out at 0 f/cm2, a discharge rate of 60 to 120 Kf/min, and a liquid temperature of each component adjusted to 30 to 40°C. The mold used was a mold for forming the outer shell of an automobile bumper with a size of 140 mm x 120 mm x 1400 holes and an inner thickness of 3 layers.
Molding was performed while adjusting the mold temperature to 60 to 70°C. A sample for measuring physical properties was cut out from the obtained molded product, and the physical properties listed in Table 3 including the water absorption dimensional change rate were measured. The results are shown in the same table.

The demolding time and physical properties described in Table 3 were measured by the following methods.

Demolding time: The time from the completion of injection until the mold can be demolded (the molded product can be demolded without cracking, etc.).

Density: method by water or alcohol displacement.

(ASTM-D792) Water absorption dimensional change rate: Molded product sample (100X2 o o
t is the length in the long side direction immediately after post-curing X 3 wn ) at 100°C for 5 hr.

If this is immersed in warm water at 40° C. for 240 hr and the length is t, then the water absorption dimensional change rate ΔL is given by the following equation.

△　L　　”　-X　1　0　0 t.

Flexural modulus: Based on ASTM-D790 method.

Tensile strength: Based on JIEI-630 dumbbell No. 2.

Elongation: Based on J Engineering El-6301 dumbbell No. 2.

Heat sag: 125 mm x 25 TmnX 3
This figure shows the amount of droop at the tip when one end of a mm test piece was held horizontally and heated in an oven at 120°C for 1 hour.

The raw materials used were as follows.

■High molecular weight active hydrogen compounds The polyethers A to G shown in Table 1 below are aminated polyethers and polyether polyols, and polyether polyols are di- to trihydric polyhydric alcohols added with propylene oxytra. This is a polyoxypropylene/oxyethylene polyol obtained by adding ethylene oxide to the polyol. Aminated polyether is an aminated polyether obtained by aminating the terminal hydroxyl group of polyoxypropylene/oxyethylene polyol synthesized in the same manner with ammonia. their number of functional groups,
The molecular weight per functional group, oxyethylene group content, and amination rate are shown in Table 1 below.

Table 1 Polyether A 3 2200 1
50t/B 3
p p
25// Q 3
u tt
50p D 3
//' 8 0
//E 3//
//70〃F
2 2000 20
0tt G 2
1500 50 0
The mixture of high molecular weight active hydrogen compounds used is a mixture of the above polyethers, and its composition ratio (weight), average number of functional groups, average molecular weight per functional group, average oxyethylene group content, and average amination rate are shown in Table 2 below.

■, Polyisocyanate compounds [The amount used is such that the incyanate index is 105] Polyisocyanate A dicarbodiimide modified diphenylmethane diisocyanate (NCo content 2a5%) Polyisocyanate B: Prepolymer type modified diphenylmethane diisocyanate (NCO content 2 & 0%) ■, Other raw materials Chain lengthening agent A: Ethylene glycol // B: 1,4-butanediol Catalyst A 33 weight ratio dipropylene glycol solution of nitriethylenediamine (trade name: DABCO 3RO LV) [Used in Table 3 A total of 000 indicates that it is substantially unused.] Catalyst B dibutyl dilaurate R-11:) Lichlorofluoromethane MFB: Milled glass fiber with an average length of about Q and 15 mm (May 1982) ρ day Commissioner of the Japan Patent Office Mr. Kazuo Wakasugi1, Indication of the case Patent Application No. 652 of 1982] No. 42, Name of the invention Reaction injection molding method 3, Person making the amendment Relationship to the case Patent applicant address 2 Marunouchi, Chiyoda-ku, Tokyo Chome 1-2 Name (
004) Asahi Glass Co., Ltd. 4, Agent 105 Address 6 Toranomon Chiyoda Building, 16-2 Toranomon-chome, Minato-ku, Tokyo Number of inventions increased by amendment None.

7. Target of amendment Column 8 of the specification "Detailed Description of the Invention", Contents of the amendment (1) Page 40 of the specification cylinder, rightmost column (Example 8), 9th line r2
Correct 0.54 to "10".

Claims (1)

[Scope of Claims] 1. A reaction injection molding method in which a high molecular weight active hydrogen compound, a chain extender, and a polyisocyanate compound are used as essential raw materials to react in the presence of a catalyst to produce a molded article of a polyurethaneurea elastomer, An aminated polyether with an average molecular weight per functional group of about 500 to 4,000 obtained by aminating some or all of the hydroxyl groups of a polyether polyol with a high molecular weight active hydrogen compound, or the aminated polyether and other high molecular weight It consists of a mixture of at least one type of active hydrogen compound, the average amination rate in the high molecular weight active hydrogen compound is 5 to 70%, the average number of functional groups is 2.0 or more, and the average molecular weight per functional group is about S
OO~4000, and the catalyst does not substantially contain an effective amount of a tertiary amine catalyst. 2. The method according to claim 1, wherein the catalyst is an organometallic compound catalyst. 5. The method according to claim 1, wherein the other high molecular weight active hydrogen compound is a polyether polyol.