JPH01272616A - Reaction injection molding - Google Patents

Abstract

PURPOSE:To obtain a molded article free from deterioration in physical properties such as extension characteristics and heat sag value, despite adding a small amount of water as an active hydrogen component, by combined use, as an amine catalyst, triethylenediamine plus a specific amine compound. CONSTITUTION:Either a raw material component containing a high-molecular weight active hydrogen compound and a chain extender or a second raw material component containing an isocyanate compound is incorporated with (I) an amine catalyst, a combination of (A) triethylenediamine with (B) an amine compound with the ratio K1/K2 greater than that for the component A (e.g., N,N,N',N'',N''-pentamethyldiethylenetriamine) (where, K1 is reaction constant in the reaction with water; K2 is reaction constant in the reaction with alcohol) and (II) a foaming agent followed by reaction injection molding using the above two raw material components.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a reaction injection molding method for molding polyurethane elastomer and 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. Applications to synthetic resins other than polyurethane resins are also known; for example, applications to polyamide resins, epoxy resins, unsaturated polyester resins, etc. are being considered, and -1 part has been put into practical use. In the reaction injection molding method, at least two fluid raw materials that rapidly react to form a synthetic resin are mixed immediately before a mold, and immediately injected into the mold, and the mixture is synthesized in the mold. This is a molding method that focuses on forming resin. 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. Hereinafter, a mixture of at least two fluid raw material components will be referred to as a reactive mixture. In addition, although the present invention will be mainly described below with reference to the production of polyurethane elastomer molded articles by reaction injection molding, application to other polyurethane synthetic resins (e.g. semi-rigid foam) and polyurea resins is denied. isn't it.

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 isocyanate 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.
8 g/cm" or more, especially about 0.9 g/cm" 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.
/cm3 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.

[Problems to be Solved by the Invention] In reaction injection molding, a method of adding a small amount of water as an active hydrogen component has conventionally been used to improve fluidity in a mold.

However, synthetic resin molded articles manufactured by adding water are accompanied by deterioration in physical properties (especially elongation and heat sag value), and it is extremely difficult to achieve both fluidity and elongation properties.

[Means for Solving the Problems] The present invention was made to solve the above-mentioned problems, and provides a raw material component containing a high molecular weight active hydrogen compound and a chain extender, and optionally blending a catalyst and a blowing agent. In a method for producing a synthetic resin molded article by reaction injection molding using at least two components, the ratio of the reaction constant K1 in the reaction with triethylenediamine and water as an amine catalyst and the reaction constant in the reaction with alcohol to 2. The present invention provides a reaction injection molding method characterized by using an amine catalyst having a value of , , and larger than that of triethylenediamine.

In the production of polyurethane elastomers, the use of catalysts is usually essential. In the present invention, a tertiary amine catalyst or an organic tin compound is usually used as a catalyst. has been measured for various amine catalysts. As an example, Table 3.3 "Reaction Activities of Representative Amine Catalysts" on page 119 of "Polyurethane Resin Handbook" edited by Keiji Iwata, published by Nikkan Kogyo Shimbun on September 25, 1988, is cited. In this table, "r (2)/(1 ratio") corresponds to "ratio to 1/2" in the present invention. According to the description in this table, x, / x x of triethylenediamine is 1.34X
10-'. In this table, examples of diamine catalysts with a large K1/2 of 2 include the following amine catalysts (the value in brackets is 10 times the ratio Kl/xz).

Bis(2-dimethylaminoethyl ether) [39,0
] , N, N, N', N'', N'-pentamethyldiethylenetriamine [37,3] , N, N, N'-trimethylaminoethyl-ethanolamine [15,0]
, dimethylaminoethoxyethanol [13,9],
l-ethylamine [5,18], N-methyl-N-(
2-dimethylamino)ethylpiperazine [4,44]
, N,N'-dimethylcyclohexylamine [3,7
6].

For amine catalysts with a preferred ratio K + /K * greater than triethylenediamine, the ratio K r /K 2
is an amine catalyst with a ratio K I / K 2 of triethylenediamine that is twice or more, particularly an amine catalyst that is three times or more. Most preferred is an amine catalyst of 10 times or more.

Although the ratio of the amount of triethylenediamine to the amine catalyst used is not particularly limited, the amount of the amine catalyst used is 0.1 to 0.1 to triethylenediamine by weight.
10, particularly preferably 0-8 to 5, among which 1 to 3
is preferred.

The total amount of triethylenediamine and the above amine catalyst is
A suitable amount is 0.1 to 5% by weight based on the high molecular weight active hydrogen compound, and particularly preferably 0.5 to 3% by weight.

In the chain extender of the present invention, an aliphatic, alicyclic, or aromatic polyamine having two or more primary amino groups or secondary amino groups is used as the polyamine. Other chain extenders are preferably low molecular weight diols, but are not limited to these, low molecular weight polyols other than low molecular weight diols, aliphatic polyamines (e.g.
Examples include low molecular weight aminated polyethers (described later), polyamines other than those mentioned above, and the like.

The above chain extenders can be used in combination with each other.

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 amine 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 suitably about 2.0 to 4.0 on average, particularly about 2.0 to 3.5. Most preferred as the high molecular weight active hydrogen compound are polyether polyols, mixtures containing polyether polyols as a main component with other high molecular weight polyols, and polymer polyols based on polyether polyols. Suitable polyether polyols are polyether polyols obtained by adding monoepoxides such as alkylene oxide, tetrahydrofuran, etc. to a polyvalent initiator, and especially those obtained by adding propylene oxide and/or butylene oxide to a polyvalent initiator together with ethylene oxide. Preferred are polyether polyols obtained by. 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, but the higher the proportion of oxyethylene groups, the higher the hydrophilicity of the polyether polyol, which in turn increases the water absorption of the polyurethane elastomer. becomes high, causing a decrease in water absorption dimensional properties. Therefore, the upper limit of the amount of oxyethylene groups present in the polyether polyol is suitably about 35% by weight, particularly preferably about 25% by weight. However, this is not the case when producing hydrophilic polyurethane. It is almost essential that at least 5% by weight of oxyethylene groups be present at the ends of the polyether chains, but they may also be 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 two or more polyether polyols containing polyether diol or polyether triol as the main component or with other polyether polyols. Mixtures are preferred.

The polymer polyol is preferably a polymer polyol based on a polyether polyol as described above. Particularly preferred is a polymer polyol obtained by polymerizing at least one of acrylonitrile, styrene, and other vinyl 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 in combination with polyether polyols include hydroxyl group-containing hydrocarbon polymers such as butadiene homopolymers and copolymers having two or more hydroxyl groups, and polyester polyols. 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 the chain extender relative to the total of the high molecular weight active hydrogen compound and the chain extender is required to be at least 3 times 1%. The greater the amount of chain extender, the harder the molded product obtained (assuming the high molecular weight active hydrogen compound is the same). In order to obtain a molded product with good heat resistance, a hard molded product using a large amount of chain extender is preferable. In the present invention, the amount of chain extender is between 5 and 5
0% by weight is preferred, especially 10 to 45% by weight,
In order to obtain particularly hard molded articles, 20 to 45% by weight is employed.

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 about 90 to I20, especially about 95 to I20, expressed as an isocyanate index! 10 is appropriate.

Blowing agents are also often used to improve the filling of reactive mixtures into molds. Polyurethane elastomers obtained using relatively small amounts of blowing agents are called microcellular (polyurethane) elastomers. 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 about 1 part by weight per 100 parts by weight of the high molecular weight active hydrogen compound.
Up to 5 parts by weight are suitable, especially about 2 to 10 parts by weight.

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, flame retardants, etc.

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 T-plate fillers. As the amount of these fillers increases, problems arise with the viscosity and operability of the raw material components, so it is preferably about 30% by weight or less, particularly 20% by weight or less, based on the total synthetic resin raw material. These additives are mainly blended into the active hydrogen compound-containing raw material component, but those that are non-reactive with isocyanate groups are also blended into the isocyanate compound-containing raw material component.

[Function 1] The synthetic resin molded product obtained by the present invention, particularly the polyurethane elastomer molded product, can be used for various purposes.

It is particularly suitable for automotive exterior parts such as bumper shells, fascias, fenders, door panels, etc. However, the application is not limited to this, and it can also be used for 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.

[Example] The following examples were conducted using the following raw material components and molding tests.

l) High molecular weight polyol A Contains oxyethylene groups with oxyethylene groups at the terminal @21ffi%, hydroxyl value 2 using glycerin as an initiator
8 polyoxypropylene oxyethylene triol is used.

2) Isocyanate B The amount of the prepolymer type modified diphenylmethane diisocyanate component containing isocyanate ff126.0% by weight is such that the equivalent ratio is 1.05 to the active hydrogen component.

(Molding test) Using a reaction injection molding device (high pressure foaming machine), the discharge output was 1
50J/cm”, discharge sokg/min, liquid temperature of each component 3
The temperature was adjusted to 0 to 40'C, and reaction injection molding was performed.

The mold cavity had a size of 350 mm x 350 mm, a wall thickness of 3 mm, and a temperature adjusted to 60-70'C. The mold was removed 30 seconds after injection, and the density, tensile strength, and heat sag of the molded product were measured.

(Tensile test) 50% modulus (kg/cm"), tensile strength fkg
/cm”l, elongation (%) is No. 2 dumbbell, tensile speed 2
Measurement was performed at a speed of 50 mm/min.

(Heat Sag (Heat Sag)) A 25 x 125 x 3 mm sample was left for 120'CX Ihr with a 100 mm overhang, and after cooling at room temperature for 30 minutes, the sagging distance was measured.

Example 1 100 parts of high molecular weight polyol A, 16.5 parts of ethylene glycol, 0.2 parts of water, and 0.0 parts of tin dilaurate.
02 parts, triethylenediamine 0.6 parts, bis(2~
Dissolve 1.0 part of dimethylaminoethyl)ether,
It was used as an active hydrogen component.

The equivalent ratio of this active hydrogen component and isocyanate B is 1.
05, and the tensile strength was measured. 50% modulus 160kg/cm", tensile strength 220kg/c
m”, elongation was 185%. Also, heat sag was 13
．． It became 5mm.

Example 2 100 parts of high molecular weight polyol Δ, 16.5 parts of ethylene glycol, 0.2 parts of water, and 0.0 parts of tin dilaurate
2 parts of triethylenediamine, 0.6 parts of triethylenediamine, and 150 parts of pentamethyldiethylenetriamine were dissolved to obtain an active hydrogen component.

The active hydrogen component and isocyanate B have an equi-1 ratio of 1
．． 05, and the tensile strength was measured. 50% modulus 157kg/cm", tensile strength 216kg/
cm”, elongation was 176%. Also, heat sag was 1
It became 3.8 mm.

Example 3 100 parts of high molecular weight polyol A, 1 part of ethylene glycol
6.5 parts, water 0.2 parts, and tin dilaurate 0.02
1 part, triethylenediamine 0.6 part, and dimethylcyclohexylamine 1.0 part were dissolved to obtain an active hydrogen component.

The equivalent ratio of this active hydrogen component and isocyanate B is 1.
05, and the tensile strength was measured. 50% modulus 155kg/cm", tensile strength 214kg/c
m”, elongation was 173%. Also, heat sag was 13
．． It became 6mm.

Comparative Example 1 100 parts of high molecular weight polyol A, 16.5 parts of ethylene glycol, 0.2 parts of water, and 0.0 parts of tin dilauret.
0.2 parts of triethylenediamine and 0.6 parts of triethylenediamine were dissolved to obtain an active hydrogen component.

The equivalent ratio of this active hydrogen component and isocyanate B is 1.
05, and the tensile strength was measured. 50% modulus 154kg/cm", tensile strength 208kg/c
m”, elongation was 153%. Also, heat sag was 16
．． It became 5mm.

Claims (1)

[Claims] 1. Manufacture a synthetic resin molded product by reaction injection molding using at least two raw material components containing a high molecular weight active hydrogen compound and a chain extender, optionally containing a catalyst and a blowing agent. The method is characterized in that an amine catalyst is used as the amine catalyst in which the ratio K_1/K_2 of the reaction constant K_1 in the reaction with triethylenediamine and water and the reaction constant K_2 in the reaction with alcohol is larger than the value of triethylenediamine. reaction injection molding method. 2. An amine catalyst having a ratio K_1/K_2 that is larger than triethylenediamine has a ratio K that is more than twice the ratio K_1/K_2 of triethylenediamine.
Claim 1 is an amine catalyst having a value of _1/K_2.
the method of. 3. The method according to claim 1, wherein an amine catalyst having a large ratio K_1/K_2 of 0.8 to 5 times the weight ratio of triethylenediamine is used as the amine catalyst.