JPS6015417A - Composition for production of skinned rigid polyurethane foam - Google Patents

Abstract

PURPOSE:The titled composition capable of forming a foam which can be released from a mold within a short time and has excellent heat resistance, prepared by using a specified isocyanate component comprising a mixture of a polyisocyanate and an oligoisocyanate prepolymer. CONSTITUTION:Use is made of a mixture of (a) an isocyanate prepolymer obtained by reacting a 4,4-diphenylmethane diisocyanate (MDI)-type isocyanate with a functionality of 2-2.3, represented by formula I (wherein l is 0-0.3) with a glycerin-type polyol with an OH value of 350-750 KOH mg/g, represented by formula II (wherein n1, n2, and n3 are each 1-2.2) or formula III (wherein n1', n2', and n3' are each 1-2.95) at an OH to NCO molar ratio of 0.1-0.3 and (b) an MDI-type isocyanate with a functionality of 2.6-3, represented by formula I (wherein l is 0.6-1) at an a/b weight ratio of 0.8-1.2. Namely, a composition is prepared by mixing a polyol (OH value of 350-800 KOH mg/g) with a reaction accelerator, a blowing agent, a foam stabilizer, and the above isocyanate mixture.

Description

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

[Background of the invention]

A hard urethane foam with a skin that is made by mixing isocyanate, a polyether having active hydrogen, a blowing agent, a catalyst, etc., foaming and hardening in a closed mold, and then pounding it has thermal insulation, sound absorption, and strength of -171 Because of its excellent properties, it is suitable for use as a material for electrical equipment, electronic parts, and building materials.In recent years, one-reaction injection molding technology (RIM technology) has developed, and the uses of the above-mentioned foam body are increasingly expanding. However, one factor limiting the industrial use of this aerated urethane product is the long molding cycle, especially the demolding time (from injecting the composition into the mold to ejecting the molded part). In other words, when the molded product is removed from the mold in a short period of time, the foam swells due to the foaming pressure, so the molded product must be kept completely in the mold for a long time. .

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

In addition, by converting all incyanate into a prepolymer,
There is a method to suppress heat generation during RIM molding and shorten demolding time. Generally, as an isocyanate for polyurethane RIM, MDI (4,4'-
Sophenylmethane isocyanate. Hereinafter, the same) type isocyanate is used in this specification.

1 = 0 to 1.0 Here, especially in the case of hard polyurethane, in order to increase the total heat resistance of the obtained molded product, polyfunctional M with l = 0.5 or more
The use of DI-based incyanate gold is an essential condition. However, the above polyfunctional 1111 with A=0.5 or more
When DI-based canine cyanate is polypolymerized with all kinds of polyols, the viscosity of the obtained prepolymer becomes high, and not only does high-pressure collision mixing in RIM become insufficient, but circulation of the stock solution by a ponder becomes impossible, making it difficult to use it industrially. There was a drawback that made it impossible. Therefore, it has been desired to develop a polyfunctional and low-viscosity bleed polymerized MDI isocyanate.

[Purpose of the invention]

An object of the present invention is to provide a composition for producing a rigid polyurethane foam with a skin, which does not have the drawbacks of the prior art as described above, can be demolded in a short time, and has excellent heat resistance.

[Summary of the invention]

The present invention achieves the above objectives by using a variety of prepolymerized incyanates.

That is, the present invention is basically characterized by using a mixture of a low-functional MDI-based isocyanate prepolymerized with a glycerin-based polyol and a polyfunctional MDI-based incyanate as an isocyanate for producing rigid polyurethane foam.

The above-mentioned blended bre polymerized incyanate has a low viscosity, and therefore has good workability, and the maximum heat generation temperature during molding is low (and the molded product does not bulge during demolding, significantly shortening the demolding time. is measured.

Furthermore, since incyanate has a high number of functional groups, it is possible to obtain a molded product with excellent heat resistance.

In particular, isocyanate highly prepolymerized with MD I "r glycerol polyol having a small number of functional groups,
The mixture obtained by mixing MDI with a large number of functional groups has a lower viscosity than normally expected. Based on this knowledge, the present inventors have arrived at the present invention.

The composition for producing hard I diurethane foam with a skin in the present invention has an OH value of 350 to 800 (KO) Img/g.
The essential components are a polyol (hereinafter abbreviated as substance (A)); a reaction accelerator for producing polyurethane; a blowing agent; and incyanate. Among the incyanates represented by the general formula (1), the incyanate has a functional group number (number of NCO groups in one molecule) of 2.0 to 2.
2, that is, the MDI incyanate of formula (1) with l = 0 to 0.2, and a glycerin polyol with an OH value of 350 to 750 and a KOI of 1 mg/g represented by the following general formula (2) or (3). ! k OH/N00 molar ratio is 0
．． Brepolymerized incyanate (hereinafter abbreviated as substance (B)) obtained by reacting at a ratio of 10 to 0.3, and (
1) The number of functional groups among the isocyanates represented by the formula: 2.
6 to 3.0, that is, formula (1) Thea = 0.6 to
1.0 (7) MDI-based incyanate (hereinafter referred to as substance (C1)
), and is characterized by a mixing ratio of B/C=0.8 to 1.2 by weight.

The isocyanate of the present invention has a functional group number and a group v y3
'! ! It is characterized by a high conversion rate (yt? proportion of incyanate reacted with lyol) and low viscosity.

FIG. 1 is an example of the results of examining the relationship between prepolymerization rate and viscosity for a conventional example and an example of the present invention. In other words, (AJ in Figure 1 is 7 = 0.1 (mm, 0 functional group number 2
．． 1) Incyanate prepolymerized with MDI gold glycerin-based yJe reol (prepolymerization 26:1
0-30%) / = 0.9 (1) MDI
The results of a study on brepolymerized incyanate (average functional group number of incyanate: 2.5), which is an example of the present invention, obtained by mixing 1ζ with a single noisocyanate at a ratio of 1:1 are shown. On the other hand, in (B) of Fig. 1, M of / = 0.5
DI″f, the same results are shown for conventional prepolymerized incyanate (number of functional groups of incyanate: 2.5) prepolymerized with the same glycerin-based polyol as above.

As can be understood from the comparison in this figure, the 1/polymerized isocyanate of the present invention has a lower viscosity than the conventional one at the same polymerization rate, and therefore, it has a lower fluidity. 1. A polyurethane composition with excellent workability is obtained.

The above is an overview of the present invention, and below, possible embodiments for embodying the present invention will be described in additional notes. That is, the antibacterial composition that can be employed in the present invention will be explained in more detail. First, the brepolymerized incyanate that can be used in the present invention, that is, the above substance (Bl) will be described.

Prepolymerization A, Socyane) (B) MDI-based isocyanate used to obtain (B) A polyisocyanate represented by the above formula (1) obtained by reacting a reaction product of aniline and formaldehyde with phosdan (However, /
=0 to 0,3). Here, l! The reason why the total value is 0.3 or less is from the viewpoint of the fluidity (viscosity) of the obtained gray Jicj reamed incyanate. This is because when the foam is entirely manufactured, the miscibility with the polyol component becomes poor.

In the present invention, the first polyol for prepolymerizing the MI)I isocyanate is represented by the general formula (2).
) MaN U (3) K-L7C1OH value is 350-7
It is a glycerin series biliol containing 50 KOHmg/g, which is obtained by total addition of propylene oxide or ethylene oxide in the presence of an alkali catalyst such as FiKOH. Here, Of(value t) of this polyol
35'0 to 750 KOHmg/g is 35'0 to 750 KOHmg/g.
0 KOHmg/g, 1:9 small, i.e. in formula (2): ni +rb+ ns) 6.
6 or, in equation (3): n/+nj+ na') 8.8
This is because if it is 5, the effect of shortening the demolding time will not be seen, and if it is greater than 750 KOHmg/g, i.e. In formula (2); ni, ns, ns (1,0 or Formula (3) ) ni: n,', rb', n3'(1
, 0, the obtained foam becomes brittle.

The prepolymerized incyanate that can be used in the present invention can be obtained by completely mixing the above-mentioned glycerin-based polyol in the above-mentioned MDI-based iffincyanate.

Preferred synthesis conditions U, all 6 MDI-based iffincyanates
It is preferable to heat the mixture to 0° C., mix all the polyols while stirring in a dry nitrogen gas atmosphere, and stir for an additional 4 to 6 hours after the mixing is complete. Here, the blending ratio of MDI-based incyanate and polyol is from 0.1 to 0.1 in terms of OH/N00 molar ratio.
It is 0.3. The reason for this is that if it is less than 0.1, the effect of suppressing the heat generation during foam generation is poor and the demolding time cannot be completely shortened, and if it is greater than 0.3, the prepolymerized incyanate This is because the viscosity becomes high.

Next, incyane HC) U is a polyfunctional incyanate obtained by total reaction of phosdan with the reaction product of aniline and formaldehyde, and in the above formula (1), 7=Q, 5-
1.0 MDI isocyanate.

The reason why A=0.6 to 1.0 is set here is that if l is smaller than 0.6, the heat resistance of the obtained foam will decrease, and if l is smaller than 1, the viscosity will be high. This is because.

The incyanate of the present invention is the above incyanate (B)
and (Q) are obtained by mixing the total weight ratio of B/C=0.8 to 1.2, where B/C is 0.8 to 1.
If it is less than 0.8, the amount of prepolymerized incyanate will be small and the demolding time shortening effect will be lost.On the other hand, if it is less than 1.2, the viscosity of the mixture will be large. This is because.

Polyols (Al) that can be used in the present invention include polyether polyols and polyester polyols. Particularly important among these are polyether polyols obtained by adding alkylene oxide to aromatic amines represented by the following general formula. It is a polyol.

R" R ■ However, R, R': I (or alkyl group n+, nI: 1.0-3.0 Specific examples of the above aromatic amine polyols include C, 4,
There are alkylene oxide adducts of 4'-noaminediphenylmethane and alkylene oxide adducts of tolylene diamine.The proportion of aromatic amine polyol in polyol (A) is determined by the viscosity of the polyol and the heat resistance of the resulting molded product. 1 Considering the balance of mechanical properties, 15 to 60
Particularly desirable is wt%. Here, the OH value of $+)ol (Al is 350 to 800 KOHmg/g
It is necessary to have T. The reason is that the OH value is 35
0KOHmg/g, J: V) If it is small, the mechanical properties of the obtained molded product will deteriorate, and the foam will swell due to the heat generated during molding, thus realizing the shortening of demolding time as intended by the present invention. This is because it will stop happening. On the other hand, if the OH value is less than 800 KOHmg/g, the resulting molded product may not be able to produce an industrially effective product;
It is necessary that the following is true. Polyol (Al ld
It may be a single polyol (1) or a mixture of various polyols. In the case of a mixture, it is sufficient that its average OH value satisfies the above conditions.

Specific examples of the reaction accelerator 2 blowing agent and foam stabilizer that can be used in the present invention are described below. First, as the reaction accelerator, various tertiary amine compounds,
There are tin compounds, etc.

Specific examples of tertiary amine compounds include triethylenediamine, trimethylethanolamine, morpholines, piperazines, and imidazole compounds.

DBUC1,8-diaza-bicyclo(5,4,0)undecene-7], alkylaminosilane, etc., and their salts4, such as acetate, formate, oxalate, phosphate, 2-ethylhexane acid salt.

Phenol salts, cresol salts, hydrochlorides, etc. can also be used.

On the other hand, examples of tin compounds include dibutyltin diacetate and butyltin diacetate.

Any other reaction promoters that can be used in this type of reaction can be applied to the present invention.

In addition to water, the foaming agents include trichloromolomethane,
These include low-boiling organic liquid compounds such as methylene chloride, and compounds that decompose to generate nitrogen gas, such as azobisisobutyronitrile. By changing this blending amount, a dense foam can be obtained. Among these, especially low-boiling point (0-60℃) rhodanized hydrocarbons have the property of easily forming a tough skin.
This is a particularly important compound in the present invention.

Foam stabilizers include, for example, oxyalkylene copolymers of polydimethylsiloxane in general and fluorine-based surfactants in general.

Other materials that can be used in the present invention include fillers,
Pigments, dyes, flame retardants, ultraviolet absorbers, etc.

[Embodiments of the invention]

Below, all specific examples and comparative examples of the present invention will be shown and explained in more detail.

In principle, the implementation of each side described below shall be based on the second
The equipment shown in the figure was used. Therefore, before explaining each specific composition, a method for obtaining a skinned rigid polyurethane foam using this equipment will be explained.

The foam obtained from the composition of the present invention can be produced by mixing the composition of the present invention, injecting it into a closed mold kept at a temperature of 40 to 80°C, and foaming and curing. However, the composition of the present invention has polyol (A)
And Pre71? After mixing with limainized incyanate,
Since the time until it becomes dull is extremely short, when molding the foam, 1 polyol (Ri mixed with 1 reaction accelerator, 1 blowing agent, foam stabilizer, and other auxiliary materials as necessary in Al) is used.
It is necessary to separately prepare the P liquid consisting of ``Zolepo'' and Limerized incyanate in advance, and mix both liquids using a high-pressure collision mixing method during foaming.

Therefore, with the conventional mixing method (mixing method using a low-pressure foaming machine), it takes a long time to mix and the mixing efficiency is low, so it is difficult to obtain a good foam with a skin even when using the composition of the present invention. .

The composition of the present invention is particularly effective in producing a polyurethane foam with a skin of natural quality, and is suitable for producing a conventional uniform foam or semi-rigid foam.

The intent of the present invention cannot be inferred from experience in producing soft foam bodies.

Shown in FIG. 2 is an example of equipment that can be used to produce rigid polyurethane foam from such compositions of the invention. This is a liquid reaction injection molding apparatus, of which FIG. 2 shows a schematic diagram.

The device shown in Figure 2 is for the case where the stock solution is not discharged.

A stock solution R containing polyol (A) 2 reaction accelerator 1 a blowing agent and a foam stabilizer stored in the stock solution tank 1; a stock solution P containing all the main components brepolymerized isocyanate stored in the stock solution tank 3; The liquid is transported to the mixing head 8 by high-pressure bombs f6 and 6, respectively, and then transferred to the temperature controller 11.
It returns to the stock solution tanks 1 and 3 via the connected heat exchanger 55. On the other hand, when discharging the raw material*, the mixing head 8 is operated by the hydraulic unit 7, and the colliding and mixed raw liquid is delivered to the closed mold 1 placed between the clamping units 90.
It is designed to be injected into the cavity Kasai of 0.

When the resin composition of the present invention is used in such a device, the density is 0.1 to 0.6 g/crtl and the thickness is 3 to 3 omr.
rL skinned rigid and negative polyurethane foam can be produced in a short time. The obtained foam is particularly effective for various electrical equipment articles, automobile parts, and audio equipment parts that require heat insulation, absorbency, weight reduction, and the like.

Hereinafter, specific examples of compositions will be described. Unless otherwise specified, the following description applies to the equipment and molding conditions shown in Table 1 below.

This is an example of 7j depending on the measurement method. Further, the units of numerical values indicating the composition of the foam and the blending ratio of the prepolymerized isocyanate are parts by weight.

Table 1 Firstly, an example of manufacturing the prepolymerized isocyanate used in the foam manufacturing example will be described, and then an example of foam manufacturing will be described.

Production of prepolymerized incyanate a (MDI isocyanate represented by the above general formula (1))
(/=0.1, NGO content: 32% by weight) 100 parts by weight was kept at 0°C, and a propylene oxide adduct of glycerin (OH value: 51oKoHrn
16.7 parts by weight of g/g) were added and stirred for 6 hours to obtain prepolymerized isocyanate a'. The OH/N00 molar ratio is 0.2, and the prepolymerization rate is m%.

The method of 51gg1a et al. (References: A, Farka
s, J, Am.

Chem, Soc, 82642 (1960)) When the NCO content in the prepolymerized isocyanate was measured, it was found to be 21.9f (jL''-7).The above prepolymerized isocyanate a' and the above general formula ( MDI-based incyanate represented by 11 (II=Q
, 9, NCO content = 30.5 weight l゛] or 1 cent) a'' was mixed at a blending ratio (weight ratio) a':a'' ~ 1:l to prepare a prepolymerized isocyanate 20-arm. (7
) NCO content is 26.2 wt.
The prepolymerization rate is 10%. The viscosity of this prepolymerized incyanate a was as low as 3 poise (25° C.), and there were no problems with fluidity.

Production of prepolymerized incyanate b MDI type incyanate represented by the above general formula (11)
(7=0.05, NCO content: 33.5 weight percent l-) 100 parts by weight was kept at 0°C, and an ethylene oxide adduct of glycerin (OH value: 600
KOHmg/g) 'c 22.4 parts were added and stirred for 6 hours to obtain prepolymerized isocyanate 6'. The prepolymerization rate is 30%. When the total NCO content in frepolymerized isocyanate b' was measured by a method such as 51gg1a, it was found to be 19.2 weight l·% and fco
The above prepolymerized isocyanate b' and the MDI inocyanate b'' (1=
o, 8.

NCO content: 30. -6% by weight) blending ratio (weight ratio)
b/: b" ~ 1:1 mixing to produce pre-I limalated isocyanate b. NGO content of b is 24.9
% by weight, and the prepolymerization rate is 15%.

That is, the polyol (AJ is a brorene oxide adduct of 4,4'-soaminodiphenylmethane (Of
(value: 450KOHmg/g) and 40 parts by weight of globylene oxide adduct of ethylenediamine (OH value: 5
10 parts by weight of trichlorofluoromethane and 0.5 parts by weight of H2O as a blowing agent. alkylene oxide-modified polydimethylsiloxane as a foam stabilizer.
Using 2.0 parts by weight of triethyleneduamine as a reaction accelerator and 0.1 g of phenol salt of DI3U (L8-noazabicyclo[5°4.0.) undecene-7)
Use all the mixtures with Okibe, mix them with 'fcR liquid,
Mix 1 with the equipment and molding conditions shown in Table 1.
Foamed and cured density: 0.35 g/cni, thickness: 2
A flat plate of □□□ was molded. The mixing ratio (weight ratio) of R liquid and P liquid was R: P = ioo: 121.

Maximum exothermic temperature during molding, demolding time 9 The mechanical properties were as shown in the column of Example 1 in Table 3 below.
That is, the maximum exothermic temperature was as low as 132° C., and the demolding time was as short as seconds.

In addition, the bending strength and Izot impact value (/' latched) are 24Okyctl and 10.0ky, respectively.
-CIvcdl Both showed high values.

Table 3 Examples 2, 3, 4.5: Using the compositions shown in each of Examples 2 to 5 in Table 2, the skin-like rigid polyurethane foam was completely molded in the same manner as in Example 1. did.

The density, maximum heat generation temperature during molding, demolding time 1, bending strength, and Izod impact value of the obtained molded products were as per Examples 2 to 3 in Table 3.
In other words, no matter which composition was used, the maximum heat generation temperature during molding was low and the demolding time was short. Both values showed good values. In particular, Examples 2 and 3 in which a zolopyrene oxide adduct of 4,4'-diaminodiphenylmethane was used as the polyol (A) had a short demolding time.

Comparative example: Incyanate was not made into a solépolymer.
A rigid polyurethane foam with a skin was molded under the same conditions as in Example 1 except for c.

As a result, the maximum exothermic temperature during molding was higher than in Example 1, and the demolding time was longer than in Example 1.

The contents will be explained in detail below.

4.40 parts by weight of a propylene oxide adduct of 4'-diaminodiphenylmethane, 40 parts by weight of a propylene oxide adduct of ethylenediamine, and parts by weight of propylene oxide or ethylene oxide adduct of glycerin are added to polyol (A) as a blowing agent. 10 parts by weight of trichlorofluoromethane, 0.5i-1it part of H2O, 2.0 parts by weight of alkylene oxide-modified polydimethylsiloxane as a foam stabilizer, 2.0 parts of triethylenediamine as a reaction accelerator, and 0 parts of phenol salt of DBU. ．．
1 part by weight was added to prepare R liquid. This R liquid and the MDI type incyanate represented by the above general formula (1)) (l=
0.6, NCO content: 30.5 heavy fiAIA'
Using a P' liquid (not a polymerized one) consisting of (-St. Molded. The weight ratio of R liquid and P' liquid was 100:105. In this case, the maximum exothermic temperature during molding was as high as 158° C., and the demolding time was as long as 198 seconds. The bending strength and Izod impact value of the molded product are each 169 kycr! .

7.3 kl -Cm/crl, and both values were lower than those of Example 1.

As specifically described in the Examples and Comparative Examples above, by using the composition of the present invention, a rigid polyurethane foam with a skin having excellent mechanical properties can be molded in a short time.

〔Effect of the invention〕

As mentioned above, by using the composition of the present invention, foam molding can be carried out in a short time, and demolding can be performed in a short time. Therefore, the molding cycle can be significantly shortened compared to the conventional method, and production can be improved. This has the effect of dramatically improving efficiency.

In addition, the obtained rigid polyurethane foam with skin is
It has the effect of having excellent heat resistance and other mechanical properties.

It should be noted that, as a matter of course, the present invention is not limited to the specific embodiments described above.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the grebolymerization rate and viscosity of blepolymerized incyanate. FIG. 2 is a schematic explanatory view showing an example of a liquid reaction injection molding apparatus for manufacturing a skinned rigid polyurethane foam using the resin composition of the present invention. 1.3... Raw solution tank, 5... Heat exchanger, 6...
High pressure pump, 7... Hydraulic unit, 8... Mixing head, 9... Clamping unit, 10...
Sealed type, l]...Temperature controller, 20...Cavity, P
...P liquid, R...R liquid. Representative Patent Attorney Masami Akimoto

Claims (1)

[Claims] 1. A polyol having an OH value of 350 to 800 KOHmg/g (hereinafter referred to as "inside the substance"), and Moon? A reaction accelerator for producing urethane, a blowing agent, an isocyanate, and an isocyanate as all essential components, and the above isocyanate is a combination of the substance 'N (B) and substance (C) defined below. A composition for producing a rigid polyurethane foam with a skin, which is a mixture and has a mixing ratio of B/C=0.8 to 1.2 by weight.Substance B: General formula (1) below. Among the compounds represented by, 4,4-diphenylmethane diisocyanate type having a functional group number (number of NCO groups in one molecule) of 2.0 to 2.3, that is, l = 0 to 0.3 in the following formula (1) Incyanate, Of (valence 35
Brepolymerized isocyanate obtained by reacting with a glycerin-based polyol k of 0 to 750 KOHmg/g at an OH/NC0 molar ratio of 0.1 to 0.3. Substance C: Among the compounds represented by the following general formula (1), the number of functional groups is 2.6 to 3.0, that is, 7=0.
4,4-diphenylmethane diisocyanate incyanate having a molecular weight of 6 to 1.0. (However, l: 0 to 1.0) Hz CHz-0+ CH2CH-0+ns HC output (However, n+, nt, na: 1.0 to 2.2
) CH-0+CH2-CHz-o+nlH (3) 1 CHx -0-1r-CH2-CH2-0-)-nlH
(However, n, /, rb', ns", 1.0~2
．． 95) 2. 2 of the above substance (A) which is a polyol
0 to 80% by weight, below 0-) Production of a rigid polyurethane foam with a skin according to claim 1, which is a polyol obtained by adding alkylene oxide gold to an aromatic amine represented by the general formula (4). Composition for use. 3. Addition of the substance (A) which is a polyol: 80 weight iJ? - Sentoha, 4 represented by the following general formula (5)
, 4'-di2o aminodiphenylmethane with an alkylene oxide. R...(5)