JPH05247169A - Polyurethane resin composition - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a polyurethane resin composition having good electric insulation, water resistance, and heat resistance and having little influence on rubber and plastic materials in contact therewith. A polyurethane resin composition comprising a mixed polyol of liquid polybutadiene polyol and castor oil, soybean oil as a diluent, and aliphatic and / or alicyclic polyisocyanate as a polyisocyanate component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a polyurethane resin composition having excellent injectability, room temperature curing property, electrical insulation property, and waterproof property, which is suitable as an insulating / waterproof material for connecting portions and end portions of electric cables, particularly as a raw material polyol. The present invention relates to a polyurethane resin composition using a liquid polybutadiene polyol.

[0002]

2. Description of the Related Art Polyurethane resins are abundant in the types of raw polyols and polyisocyanates, and by combining them, a cured resin covering a wide range of properties from soft to hard can be obtained, so various combinations are put to practical use depending on the application. ..
However, some resin raw materials have poor compatibility with each other, and when the raw materials with poor compatibility are combined, they will separate into two layers or become a cured product in an inhomogeneous state, so it is possible to freely select the composition. There are also situations where there are restrictions. For example, the liquid polybutadiene polyol having a hydroxyl group at the end, which is the object of the present invention, is an excellent polyol that gives a cured product having good electric insulation and water resistance, but its viscosity is high and mixing workability is insufficient. .. Therefore, it has been attempted to add a diluent to reduce the viscosity. Oils derived from petroleum such as paraffin oils and naphthene oils are generally used as diluents for liquid polybutadiene polyols. However, when polyurethane diluted with oil obtained from these petroleum is used for the connection part of electric cables, the oil tends to migrate to the covering material of electric wires and cables made of contacting rubber and plastic, and the characteristics of the covering material tend to deteriorate. Has a big drawback. Therefore, the most desirable improvement method is to reduce the viscosity of the liquid polybutadiene polyol without using a diluent. Therefore,
It is of course possible to use a low-viscosity polyol in combination with liquid polybutadiene polyol to reduce the viscosity, but liquid polybutadiene polyol has poor compatibility with other polyols such as polyether and polyester, and should be used in very small amounts. For example, although they can be used together without separation, these polyols cannot be used together with liquid polybutadiene to such an extent that injection workability is sufficiently satisfied. Further, in the case of a polyether polyol, the electrical insulation of the polyurethane obtained is inferior to that of a polybutadiene-based polyol, which is also a point to prevent the combined use. In the case of polyester polyols, polyester polyols obtained by ring-opening polymerization of caprolactone are liquids that are easily crystallized and have a difficulty in maintaining a stable liquid state at room temperature, and other polyester polyols may have insufficient hydrolysis resistance. This is the reason why it is prevented from being used together with liquid polybutadiene polyol.

Under such circumstances, it has been a technical subject to solve the above-mentioned problems without reducing the excellent electric insulation property and water resistance of liquid polybutadiene polyol as much as possible. In addition, since the polyurethane resin obtained from liquid polybutadiene polyol has a large number of double bonds contained in the butadiene skeleton, it has a drawback that it is easily affected by oxygen and is inferior in heat resistance in air. It was also a problem to be solved.

[0004]

It is an object of the present invention to provide a polyurethane resin composition which has the above-mentioned drawbacks of the prior art and which has good electric insulation, water resistance and heat resistance and has little influence on rubber and plastic materials with which it comes into contact. Is.

[0005]

SUMMARY OF THE INVENTION The present invention is a room temperature curable polyurethane composition containing a polyol, a diluent and a polyisocyanate as a main component, and a liquid polybutadiene polyol as a polyol component and a castor oil having a weight mixing ratio of 70:30 to 3 are used.
100 parts by weight of mixed polyol in the range of 0:70, 30 to 200 parts by weight of soybean oil as a diluent and compatibilizer, NCO having an aliphatic and / or alicyclic polyisocyanate as a polyisocyanate component, and mixed polyol The polyurethane resin composition is characterized in that a weight part selected from the range of 1.1 to 0.8 is contained as an essential component.

[0006]

EXAMPLES As a method for improving the above-mentioned problems associated with liquid polybutadiene polyols, attention is paid to castor oil, which is a naturally occurring polyol and gives a cured product having good electric insulation, water resistance and heat resistance. , And studied the combination of both. As a result, even when liquid polybutadiene polyol and castor oil are used together, the mixing ratio of castor oil is 30%.
When it exceeds, the compatibility limit is clearly exceeded and the emulsion of the liquid becomes remarkable, and when the mixture is left standing at room temperature, it tends to separate into two layers. It is recognized that the use of the ratio exceeding 30% is inappropriate. It was The viscosity at 25 ° C. of a grade product mainly composed of 1,4-trans bond, which is widely used among liquid polybutadiene polyols, is about 5500 cps, and the viscosity at 25 ° C. of castor oil is about 680 cps. The measurement results of the relationship between the ratio of the both and the viscosity immediately after mixing are shown in FIG. The polyurethane resin to be injected into the connection part of the electric wire is a mixture of A solution mainly composed of polyol and B solution mainly composed of polyisocyanate, which is cured at room temperature after injection, and when the initial viscosity is low, mixed injection Not only facilitates, but also has the effect of reducing the proportion of bubbles contained during mixing remaining in the cured product, and the initial viscosity of the injected resin is 2000.
It is preferably cps or less. From this point of view, as shown in FIG. 1, it is desirable that the mixing ratio of the liquid polybutadiene polyol and the castor oil be 50% or more of the castor oil. Have difficulty. As a method to overcome this problem, it has been found that adding soybean oil, which has a good compatibility with both liquid polybutadiene and castor oil among vegetable oils, as a diluent and compatibilizer is extremely effective. Soybean oil is a semi-dry oil obtained from a soybean seed by a pressing method or a solvent extraction method, and has an iodine value of 117 to 141,
Specific gravity 0.916-0.922, viscosity 25 ℃ about 40cps
It is a low viscosity liquid. The mixing ratio 70:30 to 30:70 in the mixed polyol of liquid polybutadiene polyol and castor oil used in the present invention was set in consideration of the balance of viscosity characteristics, cured product electrical insulation, water resistance and heat resistance. However, if it is within this range, the intended problem is markedly improved.

The appropriate proportion of soybean oil used as a diluent and a compatibilizer is 30 to 200 parts by weight per 100 parts by weight of the mixed polyol. When the amount is 30 parts by weight or less, the effect of dilution and compatibilization is insufficient, and when the amount is 200 parts by weight or more, the mechanical strength of the cured product becomes small and the reliability against external force such as vibration and compression becomes insufficient.

As the polyisocyanate component used in the present invention, those belonging to the aliphatic or alicyclic group are suitable. Tolylene diisocyanate having aromatic ring (TD
Polyisocyanates such as I) and diphenylmethane diisocyanate (MDI) are not suitable because they are particularly poorly compatible with the soybean oil used in the present invention. Hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, lysine triisocyanate and the like are suitable for the present invention, and those obtained by reacting these with a small amount of polyol to form a prepolymer can also be used. The use ratio of these in the present invention may be arbitrarily selected depending on the purpose of use from the range of the molar ratio of NCO and OH in the mixed polyol to 1.1 to 0.8. The NCO / OH ratio is good in the vicinity of 1.0 from the viewpoint of the characteristics of the cured product, and if it is too far from 1.0, the crosslinking will not be sufficiently carried out, as in the case of ordinary polyurethane resins.

The composition of the present invention may contain a colorant, if necessary.
A flame retardant, an antioxidant, a curing accelerator, etc. may be added.

Next, the present invention will be specifically described with reference to Examples and Comparative Examples. The numerical values of the composition shown in the table are parts by weight.

Example 1 Liquid polybutadiene polyol having an average molecular weight of 2800 and an OH value of 46.5 (PBR-4)
5HT, manufactured by Idemitsu Petrochemical Co., Ltd.), 70 parts by weight, 30 parts by weight of castor oil, 200 parts by weight of soybean oil, and 0.4 parts by weight of dibutyltin dilaurate as a hardening accelerator were mixed to prepare a liquid A. .. The liquid A was transparent and stable, and no tendency to separate during storage was observed. The composition of the present invention obtained by mixing 5.3 parts by weight of isophorone diisocyanate, which belongs to alicyclic polyisocyanate, to 100 parts by weight of liquid A has an initial viscosity of 720 cps and has good workability for injection into a cable connection part. Met. A sheet sample was prepared by injecting and curing this composition into a mold that had been subjected to a mold release treatment. The volume resistivity and water absorption are measured according to the JIS K6911 thermosetting resin general test method, and the tensile strength, elongation and aging tests are performed according to JIS K63.
01 Vulcanized rubber was tested according to the physical test method.

A vulcanized EP rubber sheet (100 × 100 × 1 mm) for coating an electric wire was embedded in about 200 g of this resin, heated at 70 ° C. for 14 days, and then taken out to obtain a weight increase rate, a tensile strength and an elongation. Was measured. The results of these tests are summarized in Table 1.

[0013]

[Table 1]

As can be seen from Table 1, the composition of Example 1 is excellent in electric insulation (volume resistivity), water resistance (water absorption) and aging resistance, and EP shown as an example of the electric wire coating material. Since it has relatively little effect on rubber, it is suitable for filling cable connection parts.

(Examples 2 and 3) Tests were carried out in the same manner as in Example 1 except that the compositions of polyurethane were changed to those shown in Examples 2 and 3 of Table 1. This result is also shown in Table 1.
Are summarized in. From these results, the polyurethane compositions of Examples 2 and 3 have properties suitable for applications such as filling cable connection portions.

(Comparative Examples 1, 2, 3, 4) Tests were carried out in the same manner as in Example 1 except that the compositions of polyurethane were changed to those shown in Comparative Examples 1 to 5 of Table 1. The results are summarized in Table 1.

The composition of Comparative Example 1 uses liquid polybutadiene polyol alone as a polyol, has a high insulating property (volume resistivity) and low water absorption,
In the heat aging test, the tensile strength and elongation are markedly reduced.

The composition of Comparative Example 2 uses a process oil as a diluent and a compatibilizer, and the influence test on EP rubber in Table 1 shows a large increase in rubber weight and a large decrease in tensile strength and elongation. That is a drawback.

The composition of Comparative Example 3 is the one in which the liquid A is composed only of a mixed polyol of liquid polybutadiene polyol and castor oil, and is in an emulsion state immediately after the preparation, but when left at room temperature for 2 days, the upper and lower two layers are formed. A cured product was not prepared because the liquid phase was separated.

Comparative Example 4 uses only castor oil as the polyol. It has a low viscosity and excellent injectability, and is good in terms of insulating properties of a cured product, heat aging resistance, and effect on EP rubber, but has a higher water absorption rate than the composition of the present invention, is hard and has poor rubber-like elasticity. The drawback is that the elongation is small. In addition, since castor oil contains more water than liquid polybutadiene polyol, the composition of Comparative Example 4 remarkably generated bubbles during the curing due to the generation of carbon dioxide gas, and the amount of bubbles in the cured product was large. The drawback was noticeable.

[0021]

Industrial Applicability As described above, the polyurethane composition of the present invention is suitable for filling the cable connection portion and the like due to its handling workability and cured product characteristics, and its industrial utility value is extremely high. It's a big one.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a mixing ratio and viscosity of a liquid polybutadiene polyol of the present invention and castor oil.

Claims (1)

[Claims] 1. A room temperature curable polyurethane resin composition comprising a polyol, a diluent and a polyisocyanate as a main component, wherein the weight mixing ratio of liquid polybutadiene polyol as a polyol component and castor oil is 70:30 to 30:70.
100 parts by weight of mixed polyol, 30 to 200 parts by weight of soybean oil as a diluent and compatibilizer, NCO having aliphatic and / or alicyclic polyisocyanate as a polyisocyanate component, and OH of mixed polyol The ratio of 1.1 to 0.8 is included in the range of 1.1 to 0.8, and a polyurethane resin composition is blended.