JPS6031206B2 - Polyisocyanate composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to novel polyisocyanate compositions, and more particularly to novel polyisocyanate compositions with low viscosity and storage stability obtained by the reaction of polyphenylmethane-based polyisocyanates and the condensation product of xylene and formaldehyde. It generally relates to a polyisocyanate composition that is liquid at room temperature and has excellent compatibility with polyols and the like.

What is polyphenylmethane polyisocyanate? Polyphenylmethane polyisocyanate (hereinafter abbreviated as POLYMETIC MDI) obtained by phosgenating the condensation product of aniline and formaldehyde, and diphenylmethane diisocyanate obtained by distilling and refining it. Cyanate (hereinafter abbreviated as MDI) or liquid MDI obtained by heat treating MDI
Refers to MDI polyisocyanates such as.

The above polyisocyanates are widely used in the polyurethane field because of their low vapor pressure, low toxicity at room temperature, ease of handling, and the excellent performance of the polyurethane resins obtained. There are also drawbacks, and improvements have been strongly desired.

First, storage stability is generally poor, and turbidity may occur during storage, or crystallization or precipitation may occur, resulting in blockages in polyurethane resin manufacturing equipment, decreased product performance, etc. , which brings about various inconveniences.

Secondly, it is generally not compatible with various polyols commonly used in the polyurethane field, such as polyether polyols, polyester polyols, and epoxy polyols, so it is difficult to use in fields where compatibility is important. This often caused problems in the use of the

These drawbacks can be considerably improved by, for example, reacting with a modifier such as a polyol to form a prepolymer or semi-prepolymer, or adding an appropriate solvent or plasticizer. However, the former method usually uses polyether polyols or polyester polyols as modifiers, resulting in high viscosity, reduced workability, and insufficient compatibility; Although it is often advantageous in terms of viscosity,
This results in limitations in terms of use, such as deterioration of the physical properties of the resulting resin.

Therefore, an object of the present invention is to overcome these difficulties and provide a polyisocyanate composition that has excellent compatibility with polyols. As a result of extensive research and examination in line with these objectives, the present inventors have found that polyphenylmethane-based polyisocyanates, which have an average molecular weight in the range of 200 to 3000, and have a hydroxyl group content of 5.0 to
0. It has been found that the object is achieved by using a polyisocyanate composition characterized in that it consists of a condensation product of xylene and formaldehyde in % by weight of the box.

The composition of the present invention can be used as a polyisocyanate for hard and semi-rigid foams, polyurethane rubber, foamed elastomers, adhesives, and various coating agents, and when used as a curing agent for polyurethane paints, it can prevent foaming on the surface of the paint film. It is particularly useful as a curing agent for thick-coat type high solid polyurethane paints, which have recently been attracting attention as low-pollution paints because they are difficult to form and have good bubble release.

Generally, xylene-formaldehyde condensation products are not commonly used as polyols for polyurethane resins, partly because they have a low hydroxyl group content. For this reason, an example of using a modified polyol with an increased hydroxyl group content as a polyol for two-component polyurethane paints is shown in Painting Technology 196, King 11.
However, it has received little attention in the polyurethane field, and there have been no examples of its use as a modifier for polyphenylmethane-based polyisocyanates.
The condensation product used in the present invention is produced from xylene and formaldehyde by a known method, and has an average molecular weight in the range of 200 to 3000, preferably 3.
It is in the range of 00 to 2000, and the hydroxyl group content is 5.0
~0. $% by weight, preferably from 2.5 to 0.5% by weight. It is also possible to use a product obtained by further reacting this condensation product with an active hydrogen-containing compound to modify it. In this case, as the active hydrogen-containing compound, for example, phenols such as phenol and cresol, alcohols, organic carboxylic acids, unsaturated fatty acids, acid amides, amines, epoxies, vegetable oils such as castor oil, etc. can be used. . If the average molecular weight of the xylene-formaldehyde condensation product is smaller than 200, the thermal stability of the resulting polyisocyanate composition will be reduced, and if it is larger than 3000, it will have poor compatibility with polyphenylmethane-based polyisocyanates. The resulting polyisocyanate composition also has a high viscosity, resulting in a decrease in workability.

If the hydroxyl group content is greater than 5.0%, the amount of isocyanate groups consumed during production will increase, leading to disadvantages in terms of cost, and the resulting polyisocyanate composition will also have a high viscosity.

The polyphenylmethane polyisocyanate used in the present invention is the polymeric MD1, M
D1, liquid MDI, etc. are known in the art, and these can be used alone or in combination.

Furthermore, other types of polyisocyanate compounds such as tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, etc. can be used in combination as necessary.

The composition of the present application mixes a polyphenylmethane-based polyisocyanate and a xylene-formaldehyde condensation product,
It can be obtained by reacting in a conventional manner.

In this case, polyether polyols, polyester polyols, monoalcohols such as ethanol and methanol, polyhydric alcohols with relatively low molecular weights such as ethylene glycol, propylene glycol, and glycerin, epoxy polyols, acrylic polyols,
Modifiers known in the art, such as vegetable oils, can be used in combination. Furthermore, various solvents, plasticizers, other additives, etc. can be added as necessary.

The reaction mixing ratio of the polyphenylmethane polyisocyanate and the xylene-formaldehyde condensation product should be determined depending on the type of raw materials used, the intended use and usage method of the resulting polyisocyanate composition, etc. Usually, the isocyanate group content of the polyisocyanate composition is determined to be in the range of 5% to 32% by weight, preferably in the range of 1% to 28% by weight.

Here, the effects obtained by the present invention are that by modifying polyphenyl metaso-based polyisocyanate with a xylene-formaldehyde condensation product, a large or medium increase in viscosity can be suppressed, and compatibility with polyols and storage stability can be improved. I was able to improve my sexuality.

Furthermore, by using the polyurethane resin with improved chemical resistance and adhesion obtained using the composition of the present invention as a paint, it was possible to prevent foaming of the paint film.

Therefore, the composition of the present invention has the characteristic that it can be widely used in fields where polyphenylmethane-based polyisocyanates are used, such as foams, paints, elastomers, leathers, and adhesives. However, the present invention is not limited thereto.

Note that in the examples, parts refer to parts by weight. Example 1 Polymeric MD1 (Millionate MR, Nippon Polyurethane K.K. product) 70 base and a condensation product of xylene and formaldehyde (Nicanol LLL, Mitsubishi Gas Chemical K.
．． A polyisocyanate composition was obtained by reacting 223 parts of K product) at 70 to 8,000 in a nitrogen atmosphere for 4 hours.

This polyisocyanate composition has an NCO group content of 22
．． 4% by weight, and the viscosity was 82 ps/2500. Even after this polyisocyanate composition was left at room temperature for 3 months, no insoluble matter was observed to form.

In addition, this polyisocyanate composition and polymeric Nml as a comparative example were mixed with various polyols (NCO/
Table 1 shows the degree of turbidity when mixing OH=1).

Table 1 ◎ Transparent 10 Slightly turbid × Turbid Example 2 Polyisocyanate composition and polyol component obtained in Example 1 {GPIOOO/PP200 (each Sanyo Chemical product) = 5/1 weight ratio is 100 Ikariku, A mixture of 78 parts of titanium white, 115 parts of talc, 186 parts of baryta, and 46 parts of MI0 was mixed at a ratio of NCO/OH = 1.25, and coated onto a mild steel plate using an airless coating machine to a film thickness of 200 mm.

The resulting coating film had a good appearance with no visible foaming, and its performance was also excellent. The results are shown in Table 2. Table 2 Example 3 Liquid MD instead of polymeric MDI in Example 1
A polyisocyanate composition was obtained in the same manner except that 1 (Millionate MTL, a product of Nippon Polyurethane K.K.) was used.

In this case, the viscosity when the NCO content of the polyisocyanate composition is changed by changing the amount of MTL used is
Shown in the table.

This polyisocyanate composition is well compatible with the various polyethers and polyester polyols listed in the first category.

In both cases, no insoluble matter was observed even after being left at room temperature for 3 months.

Table 3

Claims (1)

[Claims] 1 Average molecular weight 200-3000, hydroxyl group content 5
．． A liquid polyisocyanate composition which is stable at room temperature and is obtained by reacting 0 to 0.3% by weight of a condensation product of xylene and formaldehyde with a polyphenylmethane polyisocyanate.