JPS6084319A - Resin composition - Google Patents

Abstract

PURPOSE:A resin composition capable of forming a skinnned-rigid polyurethane foam of excellent surface properties in good workability within a short time, containing a specified catalyst (a mixture containing an imidazole compound and a diazabicycloalkene). CONSTITUTION:Use is made of, as a catalyst, a mixture of an imidazole compound of formula I (wherein R1 is methyl or ethyl, and R2 is H, methyl, or ethyl), e.g., 1-methylimidazole, and a diazabicycloalkene of formula II (wherein n is 3-5, and m is 3-4), e.g., 1,5-diazabicyclo[4,3,0]-undecene-7, at a molar ratio of 1:2-20. Namely, a polyol is mixed with an isocyanate, a blowing agent, a foam stabilizer, and the above catalyst to form a resin composition of preparing rigid polyurethane foams.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a resin composition for producing a skinned rigid polyurethane foam.

[Background of the invention]

A polyol having active hydrogen, a blowing agent, a polyurethane production catalyst (hereinafter referred to simply as a catalyst), an isocyanate, a foam stabilizer, etc. are all mixed together, and the mixture is foamed and cured in a closed mold to produce a polyurethane-forming catalyst. Rigid polyurethane foam with a skin has excellent heat insulation properties, sound absorption properties, and strength, making it suitable for use as materials for electrical machinery and electronic parts, and as building materials.In recent years, reaction injection molding technology has been developed.
With the development of injection molding, the uses of the above-mentioned foam bodies are expanding more and more. One factor limiting the industrial use of this aerated urethane product is the long molding cycle, especially demolding (from the time the composition is injected into the mold to the time the molded part is removed). time) is at a point where it is long. In other words, when removing the molded product from the mold in a short period of time, the skin may peel off, the 7 ohm swells, and small voids occur on the surface, so it takes a long time compared to injection molding of thermoplastic glass. Do not hold the molded product in the mold.

Conventionally known methods for shortening demolding time include increasing the amount of catalyst blended, blending a highly active catalyst, and increasing the overall liquid temperature.
There were drawbacks such as decreased fluidity and poor foam surface properties.

Among these, it is particularly effective to use a highly active tertiary amine catalyst and a sapon or a salt thereof to shorten the demolding time. However, when the above-mentioned catalyst is used, there is a serious drawback that air tends to be completely entrained during the foaming process, and voids are easily formed in the skin of the resulting molded product.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the above-mentioned conventional techniques and to provide a resin composition for molding a skinned rigid polyurethane foam with excellent surface properties in a short time. [Summary of the Invention] The present inventors investigated the relationship between the catalytic effect of various tertiary amines on the urethanization reaction, foaming behavior during foam formation, and demolding time. As a result, the ratio of the catalytic constant (kc (80°C)) at high temperature (80°C) to the catalytic constant (kc (go-c)) at low temperature (30°C) + kc (8G'
It has been discovered that a resin composition with good surface properties and a short demolding time can be obtained by using a combination of a catalyst with a large value and a catalyst with a small value of C)/kc (80'), and has thus obtained the present invention. @ That is, the present invention
- As a small catalyst for C), imitazole (hereinafter referred to as (al) in this specification) represented by the following general formula: 1 R,: -CH,, CH3-CH, - R2: H, CH3 , CH3CH2- As a dog catalyst for kc<saoc)/kc(llffc), the following Q) Noradebicycloalkenes or salts thereof (hereinafter referred to as tbl
It is called. ), and the mixing ratio ((al
The gist is that (bl) is VC between 2 and addition in molar ratio.

Figure 1 shows the relationship between the elapsed time of the composition mixed layer and the foam height when the composition is free foamed, that is, the foaming behavior of the foam. The curve 2 shows the foam foaming behavior of the conventional material. As is clear from the figure, when the composition of the present invention is used, the foam foams slowly at the initial stage, but the foaming rate of about 50% foaming layer becomes extremely high by 1 G. Form Imabari Q) Because the speed is low in the initial process, there is no air entrainment, and a molded product with no voids on the surface can be obtained.

Furthermore, Fig. 2 shows the change in hardness over time of the entire foam surface σ) hardness σ9 during the curing process after the foam has completed foaming, and 3 in the figure shows the change in hardness over time when the composition according to the present invention is used. 4 represents the change in hardness of conventional materials over time. As can be seen from the figure, when the composition of the present invention is used, the hardness increases in a short time compared to conventional materials, and therefore demolding becomes possible in a short time.

Among the catalysts used in the present invention, imidazole compounds (a specific example of al is 1-methylimidazole).

1-ethylimidazole, 1,2-dimethylimidazole, 1-methyl-2-ethylimidazole.

There are 1-ethyl-2-methylimidazole and 1,2-soethylimidazole. Among these, particularly effective catalysts are 1-methylimidazole and 1,2-dimethylimidazole because of their high catalytic activity.

Another catalyst used in the present invention is diazabicycloalkenes (specific examples of bl include 1,5-diazabicyclo(4,3,0)nonene-51,5-diazabicyclo(4,4,0) Decene-51,8-diazabicyclo(5,4,0) Undecene-71,6-diazabicyclo(5,3,0) Decene-61,6-diazabicyclo(5
,4,0) undecene-6,1,8-diazabicyclo[
:5,5.0) There is dodecene-8. Among these, particularly effective catalysts have a catalytic activity, especially kC (80°C)/kec
1,5-diazabicyclo(4,3,
0) nonene-5 and 1°8-diazabicyclo(5,4
, 0) undecene-7. Furthermore, the above-mentioned diazabicycloalkenes can also be used as salts of phenols such as phenol and cresol, or as salts of carnic acids such as 1M acetic acid, octylic acid, and stearic acid. On the other hand, among diazabicycloalkenes, compounds in which n and m in the general formula are not within the range of the present invention have low compatibility with polyols and low catalytic activity, and have low kc
(go-c)/kc<5trc) is small, so it is not an effective catalyst.

The above imidazole (al) and noazabicycloalkene (b
The mixing ratio of l is the molar ratio (al / (bl = 2
= 20 is good. The reason is ta+/
(If bl is more dog than ka, the effect of shortening demolding time will be extremely small; conversely, (al / (bl
This is because if it is smaller than 2, cracks are likely to occur on the surface of the molded product.

Further, the total blending amount of (a) and (bl) is 2 to 20 parts by weight based on 100 parts by weight of the polyol component described below, which is an appropriate amount in terms of fluidity and curability.

Next, other materials will be specifically explained.

Monoethanolamine is a polyol.

Aliphatic amines such as triethanolamine, ethylenediamine, ethylenetetramine, and ammonia are combined with ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter referred to as PO), There are aliphatic amine polyether polyols obtained by total addition of alkylene oxide, such as (abbreviated as ).Also, there are aliphatic amine polyether polyols obtained by adding alkylene oxide to alcohols such as glycerin, trimethylolpropane, diglycerin, sorbitol, and sucrose. There are alcohol-based bonoether polyols that can be used.Furthermore, tolylene diamine,
There are aromatic amine polyether polyols obtained by total addition of alkylene oxide to aromatic amines such as diaminobenzene, 4,4'-diaminodiphenylmethane, and xylylene diamine. , Others include J, H
5unders, K., CFr1sh, Po1y
Urethane Chemistry and Te
chnology + Partl Chemistry
, Partl Technology JRobert
E, Krieger Publishing Com
pany+Huntington, New York
k 1978 + rAna by David 5taly
Lytical Chemistry of the
Po1yurethanes.

Po1yurethanes: Partl J R
obertE, Krieger Publishing
Company, Huntington, New
York1979, and Keiji Iwata's ``F Lasti...
There are polyols described in "Tsuku Materials Course (2) Polyurethane Resins", Nikkan Kogyo Shimbunsha, 1975. Of particular importance among these are aliphatic amis polyols and aromatic amis polyols.

Isocyanates that can be used in the present invention include MDI (4,4'-diphenylmethane diisocyanate) obtained by reacting the reaction product of aniline and formaldehyde with phosgene, but not only MDI alone but also similar Isocyanates, ie polyphenylene polymethylene polyisocyanates, cal-diimidized MDI can also be used. Furthermore, the same applies to xylylene diisocyanate, isophorone diisocyanate, and tolylene diisocyanate, including the compounds described in the above-mentioned literature. Among these, MDI, which is called crude MDI in the urethane foam industry, and its analogues are particularly effective.

In addition to water, blowing agents include low-boiling organic liquid compounds such as trichlorofluoromethane and methylene chloride, and compounds that completely generate nitrogen gas when decomposed, such as azobisisobutyronitrile. Among these, especially low boiling point (0
Halodanized hydrocarbons (with a temperature of 60° C. to 60° C.) are particularly important compounds in the present invention because they have the property of easily forming a tough skin.

Other materials that can be used in the present invention include fillers, pigments, dyes, flame retardants, ultraviolet absorbers, etc., and these also include the contents described in the above-mentioned documents. These materials can also be incorporated into polyols or incyanates [7, and can also be impact mixed as separate components.

[Embodiments of the invention]

A specific example of mixing and injecting a composition into a closed mold is shown below. All the contents described below are examples of cases carried out using the apparatus, conditions, and test method shown in Table 1.

In addition, the unit of the numerical value showing the blending ratio of the foam composition is parts by weight - Example 1 Using the composition of Example 1 in Table 2, the equipment shown in Table 1,
When a rigid polyurethane foam with a skin was manufactured under the following conditions, a foam with good surface properties was obtained in a short time as shown in the column of Example 1 in Table 3.

Table 1 Table 2 * 1.8-diazabicyclo I:5,4,0:]undecene-7'I:*1+5-diazabicycloI:5,3,0
) / Kyo-5◎: Good surface surface condition, no defects, uneven color, or other defects, i.e., 4,4'-diaminodiphenylmethane (7) Po adduct (OH value: 430 KOHmg/
g) 40 parts by weight.

Po adduct of monoethanolamine (OH value: 650
KOHmg/g) 40 parts by weight, glycerin ty)
pQ, EO adduct type weight part 1.0 part by weight of oxyalkylene adduct of polydimethylsiloxane, 0.5ii part of water (ion-exchanged water), 8 parts by weight of trichloromonofluoromethane, and diazabicycloalkynes. As a catalyst, 0.96 parts by weight of DBU (diazobicyclo(5,4,O)undecene-7) and 1 part as a catalyst for imidazoles.
．． Solution A obtained by thoroughly mixing 3 parts by weight of 2-methylimidazole and crude MDI (NCO content: 30.5
The blending ratio of liquid B consisting of (wt%) (liquid B/liquid A: weight ratio)
1. Collision mixing using a high-pressure foaming machine in step 12 until the average density is 0.
．． A 35 g/cil skinned rigid polyurethane foam was molded. The molar ratio of 1,2-trimethylimidazole and DBU was 5:1. The demolding time was as short as 1.5 minutes, and the surface quality of the foam was good with no defects such as uneven color or voids. Also, 3 minutes 15 minutes after discharging the material
The surface hardness of the foam measured after 2 seconds was as high as 71, and the bending strength and bending modulus were 220 kg/cdl.
showed a high value.

Examples 2 to 9 Rigid polyurethane foams with a skin were manufactured using the compositions of Examples 2 to 9 in Table 2 using the same method as in Example 1 and the equipment conditions shown in Table 1. Table Example 2~
As shown in Fig. 9, a foam with excellent properties was obtained in a short time. That is, these compositions could be demolded in a short time and had a glossy surface without foam destruction or swelling even when subjected to fc. Moreover, the hardness measured after 3 minutes and 15 seconds showed a high value. Furthermore, both the bending strength and bending modulus showed good values.・Comparative Examples 1 to 5 Equipment 1 shown in Table 1 was prepared using the compositions of Comparative Examples 1 to 5 in Table 4 using the same method as in the example. Rigid polyurethane foam with skin was manufactured under the following conditions. However, Comparative Examples 1 to 5 in Table 5
As shown in the column, all had the disadvantages that the demolding time was longer or the surface quality was poorer than in Example 1.

Table 5 (Dirty 62 Surface has id , and also had the disadvantage of color unevenness. Comparative Example 2 was Example 1 and R, and only 1,2-methylimidazole was used as the f call wire, and t2 had the disadvantage of a long demolding time. Similar to Example 1, Comparative Example 3 used DBU and 1,2
Although 1,2-trimethylimidazole was used, the blending ratio (molar ratio) of 1,2-trimethylimidazole and DBU was 1:2, which had the disadvantage of generating surface voids. Example 4 also used DBU and 1,2-dimethylimidazole as catalysts, but the blending ratio (molar ratio) of 1,2-trimethylimidazole and DBU was about 1:50, and the amount of DBU blended was small. Therefore, there were some cases where demolding time was long. Furthermore, although Comparative Example 5 is an example in which a general catalyst pentamethyldiethylenetriamine was used, it had the disadvantage that demolding time was longer than in Example 1.

〔Effect of the invention〕

As specifically described in the Examples and Comparative Examples above, according to the present invention, a skinned hard yellow polyurethane foam with excellent surface properties can be molded in a short time.

The skinned rigid polyurethane foam obtained using the composition according to the invention has heat-insulating and sound-absorbing properties.

It can be widely applied to various electrical and electronic equipment parts, automobile parts, housing materials, building materials, etc., which particularly require weight reduction.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram showing the foaming behavior of the composition according to the invention and a conventional material, and FIG. 2 is a characteristic diagram showing the change in hardness of the same material over time. 1...Curve showing the foam foaming behavior when using the composition according to the present invention, 2...Curve showing the foam foaming behavior of the conventional material, 3...Curve showing the foam foaming behavior when using the composition according to the present invention Curve showing changes in hardness over time, 4...Curve showing changes in hardness over time of conventional materials. Representative Patent Attorney Tadashi Akimoto The first plan is the first one, and the second one is from the company (S).

Claims (1)

[Scope of Claims] A resin composition comprising: a catalyst for producing polyurethane; a blowing agent; a foam stabilizer; and an isocyanate; L+: CHa + CH3CH2-R2:HIC
Hs + CHs -CH2- and (bl) The diazabicycloalkenes represented by the following general formula or 1c are a mixture of their salts n: 3 to 5 m: 3 to 4, and the mixing ratio ((a): ( bl
) is between 2 and + in molar ratio, a resin composition for producing a rigid polyurethane foam with a skin.