JPS636012A - Mixture for splicing cable - Google Patents

Abstract

PURPOSE:To obtain a mixture for splicing cables, excellent in electrical insulating property, resistance to moisture and heat deterioration, applicability, safety, etc., by mixing an isocyanate group-terminated urethane prepolymer of a specified composition with a mixed polyol and a mixed plasticizer. CONSTITUTION:A bi- to tri-functional polyol of an MW of 2,000-3,000 is reacted with an excessive amount of polymethylenepolyphenylene isocyanate or an isocyanate mixture comprising this isocyanate and 4,4'-diphenylmethane diisocyanate to produce an isocyanate group-terminated urethane prepolymer. This prepolymer is mixed with a mixed polyol comprising polybutadiene-polyol and a polyol of an MW <=3,000 or castor oil and a mixed plasticizer comprising a process oil and hydrogenated triphenyl at an NCO to OH equivalent ratio of 0.9-1.2 to obtain a mixture for splicing cables.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a cable connection mixture, that is, a mixture for providing watertightness and airtightness by injecting it into a connection case at the connection part of a communication cable and curing it. This invention relates to an admixture that can be constructed and easily dismantled.

[Prior art]

Conventionally, as a mixture for cable connection having electrical insulation properties and dismantling properties, a prepolymer (liquid A) with isocyanate group terminals obtained by the reaction of castor oil and tolylene diisocyanate (hereinafter abbreviated as TDI) and castor oil or its Mixtures that harden with derivatives (Liquid B), etc. (for example, Japanese Patent Publication No. 51-24719) have been proposed; The work required a great deal of force, and there were significant drawbacks for the operator. Furthermore, the fact is that connection work is mainly carried out in narrow spaces with poor ventilation, such as manholes, tunnels, and handholes, and care must be taken in terms of environmental hygiene.
Polyurethane mixtures using I) use an isocyanate prepolymer prepared by reacting TDI with an active hydrogen compound of less than the chemical equivalent, but it is common for unreacted free TDI to exist in the prepolymer. Yes, mixed,
Another drawback is that free TDI vapor is volatilized during the injection process, increasing the isocyanate gas concentration in the working environment. In addition, as a disassembly mixture that can be used for gas maintenance cables, a mixture consisting of an isocyanate prepolymer of polyalkylene glycol and polyphenylene polyisocyanate and a diol or triol with a molecular weight of 200 to 3000 (Japanese Patent Publication No. 19174/1983) is available. Although this is known, it has the disadvantage that the cured product has high strength (and cannot be easily dismantled), and since polyalkylene gelicol is used alone, it has poor electrical insulation properties.

[Purpose of the invention]

The present invention was conceived in view of the above-mentioned current situation, and has excellent injectability, hardenability, mechanical properties, and electrical insulation.
The object of the present invention is to provide a cable connection mixture that solves the problems of disassembly, thermal deterioration, and toxicity.

[Structure of the invention]

Therefore, the present invention provides terminal isocyanate groups obtained by reacting a bifunctional or trifunctional polyol with a molecular weight of 2,000 to 3,000 with an excess of polymethylene polyphenylene isocyanate alone or a mixture of 4,4'-diphenylmethane diisocyanate. A mixed polyol (B) obtained by mixing a urethane prepolymer (A) having a polybutadiene polyol with a polyol or castor oil having a molecular weight of 3000 or less, and a mixed plasticizer (C) consisting of a process oil and partially hydrogenated triphenyl. The gist of the invention is a cable connection mixture characterized by an equivalent ratio (NCO/OH) of 0°9 to 1.2.

Hereinafter, the configuration of the present invention will be explained in detail.

The physical properties of the mixture that make it easy to disassemble are tensile strength of 1 to 6 kg.
/ad, elongation 80-150%, tear strength 0.5-1.5
kg/cffI, hardness (JIS A) 10 to 30, and the ease of dismantling is 1 to 3, depending on the result of actual dismantling work as the breaking strength by a screwdriver.
kg is desirable, and the volume resistivity value must be 10I3Ω-cm or more for electrical insulation. Furthermore, transparency is more desirable than ease of work during disassembly.

The mixture of the invention having this property has a molecular weight of, for example, 20.
Terminal isocyanate obtained by reacting a mixed isocyanate prepared by adding 0 to 50 parts by weight of diphenylmethane diisocyanate to 100 parts by weight of excess polyphenylene polyisocyanate with a 00 to 3000 bifunctional or trifunctional (having two or more hydroxyl groups) polyol. and a polyol having two or more hydroxyl groups with a molecular weight of 3000 or less or castor oil 20 to 120 parts by weight per 100 parts by weight of the isocyanate prepolymer (A) and polybutadiene polyol.
Parts by weight of mixed polyol (B) and mixed plasticizer (C
), and the NGO10H ratio is 0.9 to 1.2.

(A) The isocyanate component of the prepolymer used in the present invention is usually TDI, 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as MDI)
, liquefied MDI, polyphenylene polyisocyanate (
(hereinafter abbreviated as poly-MDI). Among these, when using TDI, MDI, and liquefied MDI,
Although it is good for increasing mechanical strength, it becomes a problem when imparting disassembly.Also, TDI poses a problem of toxicity due to free TDI in the obtained prepolymer, and MDI (liquefied MD I) has a low freezing point. Because of the high temperature, the obtained prepolymer also tends to crystallize at low temperatures (and has to be heated before use), making it unsuitable.

Because polyMDI is amorphous, the obtained prepolymer has no crystal precipitation and has extremely good workability.Also, because it has a high number of functional groups, the obtained elastomer has mechanical properties such as elongation and tear strength. Because of its small characteristics, it is possible to obtain an elastomer that is easy to disassemble, and it is found that it is a preferred isocyanate for the purpose of the present invention.Moreover, MDI can also be used as a mixed isocyanate with this isocyanate, and problems with disassembly and crystal precipitation can be avoided. The mixing ratio of MDI is 5.
It is preferably used within 0%.

Next, the polyol used in the present invention is usually
Castor oil or polyalkylene ether polyols with a molecular weight of t2000 to 3000, for example, addition polymerization of propylene oxide or ethylene oxide using a diol such as ethylene glycol or a triol such as trimethylolpropane or glycerin as an initiator, or polybutadiene polyol, etc. These may be used alone or in a mixture of two or more, but among these, polyalkylene ether polyols having a molecular weight of 2,000 to 3,000 are preferably used in order to reduce the viscosity of the prepolymer.

(B) The mixed polyol used as a curing agent for the prepolymer is usually one of the above-mentioned polyols, low molecular weight diols, triols, etc., or two of them.
It is preferable to use it as a mixture of more than one species. The polybutadiene polyol, castor oil, or castor oil derivative used as a curing agent is hydrophobic, so it prevents foaming due to water absorption during the curing reaction when mixed with the above-mentioned prepolymer, and the resulting elastomer has moisture resistance, low temperature resistance, and electrical properties. Has insulation properties.

(C) Furthermore, the mixture obtained by reacting the isocyanate prepolymer with a compound containing active hydrogen used as a curing agent has a high viscosity, making it difficult to inject, and having poor fluidity, making it difficult to penetrate into gaps, making it difficult to desorb. It also causes disadvantages such as bad temper. In addition, the hardness and other physical properties of the cured product increase, resulting in the disadvantage that it becomes difficult to dismantle. Therefore, it is necessary to use a plasticizer that is highly compatible with the isocyanate prepolymer, the curing agent, or the cured product of both.

Furthermore, the plasticizer used here must be inert towards isocyanate groups in view of storage stability. Examples of plasticizers used for this purpose include aliphatic dicarboxylic acid esters such as dibutyl sebacate, dioctyl adipate, and dioctyl sebacate, as well as polybutene, process oil, partially hydrogenated triphenyl, etc. Ester plasticizers is unsuitable because it tends to undergo hydrolysis due to heat.

Process oils that do not undergo hydrolysis due to heat and have excellent electrical insulation properties are suitable, but the drawback is that they have a low affinity for cured urethane products and have difficulty in compatibility, resulting in bleeding and poor transparency. Problems such as chipping may occur. In order to solve these problems, as a result of intensive studies, it was found that it is preferable to use a mixed plasticizer made by mixing partially hydrogenated triphenyl with process oil, which has excellent compatibility with cured urethane products and process oil. . By using this, a transparent and bleed-free mixture can be obtained without impairing electrical insulation, disassembly, or mechanical properties. The amount of this mixed plasticizer is 100 to 250 parts by weight, depending on the type of urethane composition, per 100 parts by weight of the urethane resin (urethane prepolymer and curing agent).
When added within the range of parts by weight, the target performance is satisfied.

Further, as a catalyst for promoting conversion into a urethane resin, a curing catalyst generally used for producing polyurethane may be used.

As described above, the mixture of the present invention consisting of the urethane prepolymer (A) having a terminal isocyanate group, the mixed polyol (B) and the mixed plasticizer (C) has an equivalent ratio (NCO/
OH) must be between 0.9 and 1.2. this is,
If the hardness is less than 0.9, the hardness is too low (pudding-like) and the wire cannot be restrained, and it is also difficult to dismantle it. - On the other hand, if it exceeds 1.2, it will not harden.

Although the mixing ratio of these components is not specified, the mixed polyol (B) is 130 to 170 parts by weight and the mixed plasticizer (C) is 200 to 500 parts by weight to 100 parts by weight of the urethane prepolymer (A). Parts by weight are preferred.

Table 1 below shows a comparison of the properties of various polyisocyanates.

EXAMPLES The present invention will be explained in more detail by giving Examples and Comparative Examples below.

Examples, Comparative Examples (a) Example 1゜Polyphenylene polyisocyanate (NC0% 31.1
) and diphenylmethane diisocyanate (N00%33
．． 6) in a ratio of 6:4 at 50°C (NC
0%32. , 1) 100 g and a diol with a molecular weight of 2000 (011 m in polyoxypropylene glycol)
56) 30 g and 315 g of partially hydrogenated triphenyl
After reacting at ℃ for 4 hours, NC0% 6.8, viscosity 110c
An isocyanate prepolymer (1) having a temperature of ps/25°C was obtained.

Polybutadiene (OHNa46.6
) 100 g and 20 g of castor oil (OH!1h160)
, 30 g of partially hydrogenated triphenyl, and 2 refined process oils.
20g and 0.3 dibutyltin dilaurate as a catalyst.
curing agent (with a viscosity of 300 cps/25°C).
2) was obtained.

Isocyanate prepolymer 1) 24.5g and curing agent (
2) The mixture of the present invention was obtained by stirring and mixing both at a ratio of 100 g. The formulation contents in this case are summarized in Table 2 below.

The properties of the cured product are tensile strength 1.6 kg/aa, elongation 1
The cured product had a tear strength of 0.6 kg/cm, a hardness of 10, and a volume resistivity of 5.5×10'3 Ω-cm, and no bleeding of the plasticizer from the cured product was observed.

In addition, the hardened resin has a driver entry speed of 10 to 5
It had a breaking force of 1.2 kg in 00mIII 1 minute and could be easily removed, allowing the connection to be dismantled without any damage to the conductor. The characteristics are summarized in Table 3 below.

('b) Example 2゜Polyphenylene polyisocyanate 1- (NC0%31
．． 1) and diphenylmethane diisocyanate (N00%
33.6) at a ratio of 6:4 at 50°C with stirring (NC0% 32.1) too g, and a molecular weight of 300
0 tryol (polyoxypropylenated glycerin 0HNch56) 20g and partially hydrogenated triphenyl 70g
The isocyanate prepolymer (1) having an NC of 0% 16 and a viscosity of 300 cps/25°C was obtained by reacting with g at 50°C for 48 hours.

Polybutadiene (OH11m46.
6) 100 g and refined castor oil (OH11h160)
30g and low functional EO addition polyol (OH size 620)
7 g, 50 g of partially hydrogenated triphenyl, 147 g of refined process oil, and 0.3 g of dibutyltin dilaurate as a catalyst were stirred and mixed to give a viscosity of 470 cps/
A curing agent (2) at 25°C was obtained.

A mixture of the present invention was obtained by stirring and mixing 19.5 g of isocyanate prepolymer (1) and 100 g of curing agent (2). The formulation contents in this case are summarized in Table 2 below.

The properties of the cured product are tensile strength 4.7kg/cut and elongation 1.
10%, tear strength l, l kg/cm, hardness 30
, the volume resistivity was 2.8 x 10" Ω-cm, and no bleeding of plasticizer from the cured product was observed as in Example 1. Furthermore, the cured resin had a driver entry speed of 10 to 500 mm/min. The breaking force was 1.7 kg, and the joint could be easily dismantled as in Example 1.The characteristics are summarized in Table 3.

(C) Comparative Example 1゜ Isocyanate prepolymer of the same formulation as Example 2 (1
) and -part The properties of the cured product obtained by substituting 50 g of partially hydrogenated triphenyl in curing agent (2) and 197 g of refined process oil are as follows: tensile strength 5.3 kg/cal, elongation 120%.
, the tear strength was 1.0 kg/am, the hardness was 25, and the volume resistivity was 3.5×10 14 Ω-cm, and the bleeding of the plasticizer from the cured product was extremely unsuitable for use.

The formulation contents are shown in Table 2, and the characteristics are shown in Table 3.

(d) Comparative Example 2゜Terminal isocyanate prepolymer (NC0% 10) obtained by reacting 100 g of castor oil (OH magnetic 160) with 80/2059 g of tolylene diisocyanate (NC0% 10) 100
65 g of dioctyl sebacate was mixed with stirring to obtain (1).

On the other hand, 73 g of castor oil and 9 g of epoxidized fatty acid ester
and 0.35 g of tolylene diamine as a catalyst were added and mixed with stirring to obtain (2).

Isocyanate prepolymer (11200g and curing agent <
For example, there is an SUD compound obtained by stirring and mixing 21,100 g.

The properties of this material were a tensile strength of 7 kg/cm, an elongation of 70%, a tear strength of 2.0 kg/am, a hardness of 43, and a volume resistivity of 1.3×10”Ω-cI11. Although no plasticizer bleed was observed, the breaking force was as high as 3.5 to 4.6 ksr at a driver entry speed of 10 to 500 mm/min, making it difficult to dismantle.

The formulation contents are shown in Table 2, and the characteristics are shown in Table 3.

(Space below this page) ■ Tensile strength, elongation, tear strength, hardness: JIS-6
According to 301. Viscosity 2B type viscometer, volume resistivity: J
According to IS-K 6911.

■ Driver breaking strength test method: Cured product dimensions W 40 Dragon x L 40 mm
The maximum force when the tip of the driver breaks the cured product was measured at 0 mm/min.

〔Effect of the invention〕

As is clear from the above description, the mixture of the present invention has excellent electrical insulation properties and thermal deterioration, is low in toxicity, and can be replaced extremely easily and in a short time using a simple jig such as a screwdriver or knife. Since it can be disassembled, it has many advantages in terms of construction, health and safety, and economics as a mixture for connecting communication cables, and its application effects are large.

Claims (1)

[Claims] A urethane prepolymer (A) having terminal isocyanate groups obtained by reacting a bifunctional or trifunctional polyol with a molecular weight of 2,000 to 3,000 with an excess of polymethylene polyphenylene isocyanate alone or a mixture of 4,4'-diphenylmethane diisocyanate. ), a mixed polyol (B) made by mixing a polybutadiene polyol, a polyol with a molecular weight of 3000 or less or castor oil, and a mixed plasticizer (C) made of a process oil and partially hydrogenated triphenyl, and the equivalent ratio (NCO
/OH) is 0.9 to 1.2.