JPH0586163A - Low-viscosity polymethylene polyphenylene polyisocyanate composition prevented from crystallization - Google Patents

Abstract

PURPOSE:To provide the title compsn. which is excellent in storage stability at low temp. and in workability by specifying the viscosity of the compsn. and the content and isomer ratio of diphenylmethane diisocyanate. CONSTITUTION:The title compsn., which is stable liq. at normal temp., comprises a polymethylene polyphenylene polyisocyanate of the formula (wherein n is 0 or an integer), contains 50-70wt.% diphenylmethane diisocyanate of which 10-70wt.% is 2,4-diphenylmethane diisocyanate, and has a viscosity at 25 deg.C of 130cps or lower. The content of diphenylmethane diisocyanate lower than 50wt.% increases the viscosity and adversely affects the workability, though it improves the low-temp. storage stability; that higher than 70wt.% causes precipitation of crystals at low temp., resulting in a poor storage stability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyisocyanate composition, and more particularly to a polymethylene polyphenylene polyisocyanate mainly composed of diphenylmethane diisocyanate (a liquid polyisocyanate derived from the formula (1) and stable at room temperature). Nate composition (hereinafter simply referred to as polyisocyanate)].

[0002]

[Chemical 2]

Diphenylmethane diisocyanate and polymethylene polyphenylene polyisocyanate mainly composed of this are important as raw materials for polyurethane.

[0004]

2. Description of the Related Art Diphenylmethane diisocyanate is a solid substance having high reactivity and excellent physical properties, and therefore, it is advantageously used as a raw material for urethane foam and elastomer, and is frequently used for consolidation of soft ground. ing.

The industrially used diphenylmethane diisocyanate contains 4,4'-diphenylmethane diisocyanate (hereinafter referred to as 4,4'-MDI) as a main component and is a solid at room temperature, and therefore it is handled. It is inconvenient and has the drawbacks that if it is repeatedly heated and melted during use, it is susceptible to alteration and that impurities containing dimer as a main component are easily generated during storage. Therefore, its handling requires extreme caution.

On the other hand, since crude diphenylmethane diisocyanate (hereinafter referred to as crude-MDI) is a liquid at room temperature, it is not necessary to heat and melt it as pure diphenylmethane diisocyanate when used. Therefore, when heat insulating construction of urethane foam at a construction site, prevention of spring water in civil engineering work, and consolidation of rock mass in a coal mine are performed, crude-MDI is exclusively used because heating is difficult.

However, for these purposes, the crude-MDI is often stored for a long time in a cold region in winter or transported for a long time in an extremely cold region overseas. In such a case, diphenylmethane is contained in the crude-MDI. Diisocyanate precipitates to form a slurry and the viscosity rises, making it difficult to use, and further progressing solidifies the whole, making it completely unusable.

[0008]

In order to solve these drawbacks, there is known a method of modifying diphenylmethane diisocyanate and polymethylene polyphenylene polyisocyanate with various modifiers. -7545, 45-41219,
Modification with an organic phosphorus compound such as phosphoric acid or phosphonic acid esters described in JP-A-46-5146 and JP-A-46-5147 is effective.

[0009] A common drawback of these modification methods using organic phosphorus compounds is that diphenylmethane diisocyanate dimers (hereinafter simply referred to as "dimers") are easily formed during modification. When the insoluble matter that has precipitated after denaturation is filtered off, a transparent poisocyanate can be obtained temporarily,
Since this product is saturated with dimer, it tends to form insoluble matter again with time when stored at room temperature.

As the modification proceeds, the isocyanate group content (J
Pursuant to the purity analysis method in the IS K1556-1968 tolylene diisocyanate test method. A method in which a sample is reacted with an excess amount of di-n-butylamine and then back titrated with hydrochloric acid. same as below. ), The insoluble matter disappears,
Workability deteriorates due to high viscosity, and especially due to recent freon regulations, a method of adding water to the polyol component is being used as a method without using freon, but due to poor compatibility with polyol and water There is a problem that the viscosity of the composition becomes high and the workability is poor, and in order to solve this problem, a low viscosity isocyanate is desired.

Further, in order to obtain a polyurethane having excellent physical properties, it is preferable that the isocyanate group content of the polyisocyanate is high. On the other hand, if the isocyanate group content is too high, crystals of diphenylmethane diisocyanate are precipitated. Therefore, the isocyanate group content of the polyisocyanate is required to be in the range of 27 to 33%.

However, when diphenylmethane diisocyanate and polymethylene polyphenylene polyisocyanate are heated in the presence of an organic phosphorus compound to be modified until the isocyanate group content becomes 27 to 33%, insoluble matter is extremely generated. Is remarkable. Therefore, not only a complicated filtration operation and an operation of decomposing and recovering the dimer are required, but also the obtained polyisocyanate forms an insoluble matter with time, and there are many problems for industrial implementation.

[0013]

DISCLOSURE OF THE INVENTION The inventors of the present invention have attempted to solve these problems and have made earnest studies on a method for producing industrially advantageous polyisocyanate. As a result, diphenylmethane diisocyanate of 50 to 70% by weight has been obtained. 2,4'-diphenylmethane diisocyanate (hereinafter referred to as 2,4'-MDI) among the diphenylmethane diisocyanates contained.
Is written. ) Is 10 to 70%, and the viscosity at 25 ° C. is 130 cps or less, the polymethylene polyphenylene polyisocyanate composition has a low viscosity without forming an insoluble matter even when stored at a low temperature. I found that it was stable.

That is, the present invention relates to crude-MDI 4,
50% to 70% of 4'-MDI and 2,4'-MDI of diphenylmethane diisocyanate are contained, and 10 to 70% of diphenylmethane diisocyanate is 2,4'-M.
It is a low viscosity polymethylene polyphenylene polyisocyanate composition which is DI and is crystallized.

Crude-MDI usually uses a stoichiometric excess of aniline with respect to formaldehyde, performs a condensation reaction in the presence of an acid catalyst at a temperature of room temperature to 130 ° C., and distills excess aniline. As a residue obtained by reacting the recovered residue with phosgene in the presence of a solvent and then partially distilling and separating diphenylmethane diisocyanate, or
It can be obtained by recovering excess aniline and then reacting the residue obtained by partially distilling and separating diaminodiphenylmethane with phosgene.

Diphenylmethane diisocyanate was obtained by distillation during the production of crude-MDI, and 2,4'-MD was obtained.
I is separated as a low boiling point component, but usually 4,4'-MD
2,4'-MDI diphenylmethane diisocyanate containing 30 to 70% of I (hereinafter, 2,4-rich MDI
It is obtained as.

These crude-MDI, 4,4'-MD
The content of diphenylmethane diisocyanate using I, 2,4-rich MDI is 50 to 70%, preferably 5
Mix to 0-60%. If it is less than 50%, the storage stability at low temperature is improved, but the viscosity is high and the workability is deteriorated. On the other hand, if it exceeds 70%, crystals of diphenylmethane diisocyanate precipitate when stored at low temperature, resulting in poor storage stability.

Furthermore, the proportion of 2,4'-MDI in diphenylmethane diisocyanate must be adjusted so as to be 10 to 70%, preferably 20 to 50%. If it is less than 10%, the crystallinity of 4,4'-MDI is high, so that the storage stability at low temperature becomes poor. If it exceeds 70%, the content of 2,4'-MDI in 2,4-rich-MDI is reduced. Since it has to be further increased, it is necessary to increase the distillation efficiency, resulting in high cost, and easy precipitation of crystals of 2,4′-MDI, resulting in poor storage stability at low temperatures.

The viscosity of the present composition is preferably 130 cps or less, and if it exceeds it, the viscosity becomes high when mixed with the polyol component, resulting in poor workability. Especially when the polyol component contains water for the purpose of water foaming, water is often incompatible with the polyol component and thickens in many cases, so that the viscosity at the time of working can be lowered by using the low viscosity isocyanate component of the present invention. You can

[0020]

EXAMPLES The present invention will be specifically described with reference to the following examples. Example 1 Crude-MDI [NCO content 31.6%, diphenylmethane diisocyanate content 14.4% (2,4'-M
DI 5.56%, 4,4'-MDI 94.44
%), Polymethylene polyphenylene polyisocyanate content 85.6%] 538 g, 2,4'-rich MDI
[NCO content 33.6%, diphenylmethane diisocyanate content 100%, (2,2′-MDI 0.6
0%, 2,4'-MDI 37.60%, 4,4'-M
DI 61.70%)] 184 g, 4,4'-MDI
[NCO content 31.6%, diphenylmethane diisocyanate content 100%, (2,4'-MDI 1.4
0%, 4,4'-MDI 98.6%] 278 g were mixed, and the diphenylmethane diisocyanate content was 53.9.
3%, of which 2,4'-MDI content ratio is 14.35%
Polymethylene polyphenylene polyisocyanate composition was prepared. The viscosity at 25 ° C. was 97 cps.
It was stored at -5 ° C and -25 ° C. The results are shown in Table 1.

Example 2 Crude as in Example 1-MDI 538g, 2,4'-
Rich MDI 322g, 4,4'-MDI 140g
And mixed with diphenylmethane diisocyanate content 5
5.83%, of which the 2,4'-MDI content ratio is 23.
A 62% polymethylene polyphenylene polyisocyanate composition was prepared. The viscosity at 25 ° C. was 103 cps. It was stored at -5 ° C and -25 ° C. The results are shown in Table 1.

Example 3 Crude as in Example 1-MDI 538g, 2,4'-
459 g of rich MDI and 3 g of 4,4′-MDI were mixed, and the diphenylmethane diisocyanate content was 55.
12%, of which the 2,4'-MDI content ratio is 32.84
% Polymethylene polyphenylene polyisocyanate composition was prepared. The viscosity at 25 ° C. was 108 cps. It was stored at -5 ° C and -25 ° C. The results are shown in Table 1.

Comparative Example 1 (Over 70% diphenylmethane diisocyanate) Crude as in Example 1-MDI 538 g, 2,4'-
Rich MDI 728g, 4,4'-MDI 396g
And diphenylmethane diisocyanate content 7
2.30%, of which 2,4'-MDI content ratio is 23.
A 60% polymethylene polyphenylene polyisocyanate composition was prepared. The viscosity at 25 ° C. was 48 cps. It was stored at -5 ° C and -25 ° C. The results are shown in Table 1.

Comparative Example 2 (less than 50% diphenylmethane diisocyanate) Crude as in Example 1-MDI 538 g, 2,4'-
Rich MDI 125g, 4,4'-MDI 202g
And diphenylmethane diisocyanate content 4
6.70%, of which the 2,4'-MDI content ratio is 13.
A 17% polymethylene polyphenylene polyisocyanate composition was prepared. The viscosity at 25 ° C. was 171 cps. It was stored at -5 ° C and -25 ° C. The results are shown in Table 1.

Comparative Example 3 (Less than 10% of 2,4'-MDI) Crude-MDI 538g, 2,4'-as in Example 1
Rich MDI 46g and 4,4'-MDI 355g were mixed, and diphenylmethane diisocyanate content 5
0.96%, of which the 2,4'-MDI content ratio is 5.5
A 3% polymethylene polyphenylene polyisocyanate composition was prepared. The viscosity at 25 ° C. was 128 cps. It was stored at -5 ° C and -25 ° C. The results are shown in Table 1.

[0026]

[Table 1]

[0027]

EFFECTS OF THE INVENTION According to the present invention, the viscosity is lower than that of the conventional crude-MDI, the workability is excellent, and the storage stability at low temperature is excellent, so that it may be deteriorated during storage or transportation in cold regions in winter. It is a very advantageous method.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazushige Nitta 30 Asmuta-cho, Omuta City, Fukuoka Prefecture Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Kaoru Kuroda 30 Asamuta-cho, Omuta City, Fukuoka Prefecture 30 Mitsui Toatsu Chemistry Within the corporation

Claims (1)

[Claims] 1. In a polymethylene polyphenylene polyisocyanate [liquid polyisocyanate stable at room temperature derived from formula (1)] composition mainly composed of diphenylmethane diisocyanate, 50 to 70 parts by weight of diphenylmethane diisocyanate is used. %, And the ratio of 2,4′-diphenylmethane diisocyanate in diphenylmethane diisocyanate is 10 to 70% by weight.
A polymethylene polyphenylene polyisocyanate composition having a viscosity at 5 ° C. of 130 cps or less. [Chemical 1]