JP3340762B2 - Admixture for sealing cable connections - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an admixture for sealing a cable connection portion, that is, a method of injecting and hardening into a connection case in connection of a communication cable, or a method of preliminarily hardening into a sheet. The present invention relates to an admixture that imparts watertightness and airtightness by a method of wrapping and integrating the entire connection portion by using force, and can be easily constructed and easily disassembled.

[0002]

2. Description of the Related Art Conventionally, an isocyanate group-terminated prepolymer (A) obtained by the reaction of castor oil with tolylene diisocyanate (hereinafter abbreviated as TDI) has been known as an admixture for sealing a cable connection portion having electrical insulation and disassembly properties.
(For example, Japanese Patent Publication No. 51-24719), which is hardened with castor oil or a derivative thereof (liquid B), and the like. The dismantling work required great power for dismantling work, and there were remarkable drawbacks in the work.

Further, the connection work is mainly performed in a narrow place with poor ventilation, such as a manhole, a cave, a handhole, and the like. The above-mentioned admixture (polyurethane admixture using TDI as an isocyanate) uses an isocyanate prepolymer obtained by reacting TDI with an active hydrogen compound having a chemical equivalent or less, and unreacted free TDI is contained in the prepolymer. It is usually present. There is also a disadvantage that free TDI vapor is volatilized during the mixing and pouring operations, and the isocyanate gas concentration in the working environment increases.

Also, as a mixture for sealing a cable connection portion, a polyol having a molecular weight of 2,000 to 3,000 and polymethylene polyphenylene isocyanate alone or 4,
4'-diphenylmethane diisocyanate mixture to isocyanate terminated prepolymer obtained by reacting a polybutadiene polyol having a molecular weight of 3,000 or less polyols or castor oil mixed with a mixed polyol and process oil and partially hydrogenated triphenyl comprising mixing a plasticizer Is blended such that the equivalent ratio (NCO / OH) is 0.9 to 1.2 (JP-A-63-6012).
It has been known.

However, this is due to the equivalence ratio (NCO / O
Since H) is as high as 0.9 to 1.2, there is a drawback that when it is processed into a sheet shape, it is easily cracked when bent, and there is no adhesive force and the application is limited to injection only.

As a disassemblable admixture usable for a gas maintenance cable, an admixture comprising an isocyanate prepolymer of polyalkylene glycol and polyphenylene polyisocyanate and a diol or triol having a molecular weight of 200 to 3000 (Japanese Patent Publication No. 56-19174)
However, this has the disadvantage that the cured product has a high strength, cannot be easily disassembled, and is poor in electrical insulation because polyalkylene glycol is used alone. Was.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above situation, and has excellent workability, injectability, curability, mechanical properties, electrical insulation, disassembly, wet heat deterioration, and the like.
It is an object of the present invention to provide a mixture for sealing a cable connection which has solved the problem of toxicity.

[0008]

According to the present invention, an excess of polymethylene polyphenylene isocyanate alone or 4,4'-diphenylmethane diisocyanate is added to a di- or tri-functional polyol having a number average molecular weight of 2,000 to 3,000. urethane prepolymer mixing isocyanate is reacted with terminal isocyanate group obtained by (a), the polyol of the following number-average molecular weight of 3000 with respect to 100 parts by weight of polybutadiene polyol and polybutadiene polyols or / and castor oil 6
0 polyol component selected from mixed polyol obtained by mixing in a blending ratio of less parts by weight (B) and process oil and partially hydrogenated triphenyl a mixed plasticizer comprises (C), polyol urethane prepolymer (A) The mixing ratio of the component (B) is from 0.4 to 0.4 in equivalent ratio (NCO / OH).
The above object of the present invention is achieved by providing a mixture for sealing a cable connection portion, wherein the mixture has a ratio of 0.8.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the constitution of the present invention will be described in detail, but more preferable embodiments and advantages based thereon will be apparent.

The mixture of the present invention is a mixture of the components (A), (B) and (C) described in detail below.
Simultaneously with the mixing, the reaction of the isocyanate group of the component (A) and the hydroxyl group of the component (B) proceeds, whereby the mixture hardens, and the type and equivalent ratio of the components (A) and (B) (NCO /
OH), the degree of curing is determined over time.
In the present invention, the admixture is a concept including a mixture of the components (A), (B) and (C), and a mixture obtained by reacting an isocyanate group with a hydroxyl group and curing the mixture.

Urethane Prepolymer (A) Polymethylene polyphenylene isocyanate (sometimes abbreviated as polyMDI) is used as an isocyanate component for synthesizing a urethane prepolymer.

The above poly-MDI isocyanate component
In addition, 4,4'-diphenylmethane diisocyanate (MDI) may be used in combination.

A polyol which is another component for synthesizing the urethane prepolymer has a number average molecular weight of 2,000.
A polyol having an average of 2 to 3 hydroxyl groups per molecule.

More specifically, polyalkylene ether polyols obtained by addition-polymerizing alkylene glycols such as ethylene glycol and propylene glycol, alkylene oxides exemplified by ethylene oxide and propylene oxide to trimethylolpropane, glycerin and the like;
Other examples include polybutadiene having both ends hydroxylated. These polyols can be used alone or in combination. Among these, the use of a polyalkylene ether polyol is preferred because the viscosity of the prepolymer becomes low.

Polyol Component (B) The polyol component (B) is a polybutadiene polyol, that is, a polybutadiene having both hydroxyl groups at both ends (sometimes abbreviated as OH-PB) alone, or the OH-PB having a number average molecular weight of 3000 or less. A mixed polyol obtained by mixing a polyol or castor oil is used.

OH-PB has excellent electrical insulation properties, is suitable as the component (A) and a polyol component to be cured, and can be used alone. However, as the molecular weight increases, the viscosity increases, and it becomes difficult to prepare the mixture of the present invention when used alone. Therefore, for the purpose of adjusting the viscosity, a polyol having a number average molecular weight of 3000 or less and / or a mixed polyol mixed with castor oil is used. Used as a polyol component.

The number average molecular weight of the OH-PB used as the component (B) is about 1,000 to 3,000, preferably 1200 to 2,800.

As the polyol having a number average molecular weight of 3000 or less used in combination with the OH-PB, the molecular weight of 2000 to 2000 used in synthesizing the urethane prepolymer (A) is used.
3000 polyalkylene ether polyols, polyalkylene glycols such as polyethylene glycol, polypropylene glycol and the like; low molecular weight diols such as ethylene glycol and propringolyl; low molecular weight triols such as trimethylolpropane and glycerin. These can be used alone or in combination of two or more.

Another component used in combination with OH-PB is castor oil. Of course, castor oil can be used in combination with the polyol component described above.

The mixing ratio of the OH-PB and the polyol component or castor oil is appropriately selected according to the molecular weight of the OH-PB. The polyol component or the castor oil is at most about 100 parts by weight per 100 parts by weight of the OH-PB, and is preferably about 100 parts by weight or less. The content is 60 parts by weight or less.

The component (B) acts as a curing agent for the component (A). However, since OH-PB and castor oil are hydrophobic, they prevent foaming due to water absorption during curing, and the cured product exhibits rubber elasticity. The cured mixture is excellent in moisture resistance, low temperature resistance, and electrical insulation. In this sense, as the component (B), a combination of polybutadiene having hydroxyl groups at both ends and castor oil is preferable.

(C) A cured product obtained by mixing the mixed plasticizer component (A) and the component (B) has a high viscosity as it is, and therefore has good compatibility with the cured product.
A plasticizer inert to the isocyanate is blended. By adding this plasticizer, the injectability, sheet formability, and deaeration are improved, and the workability on site is improved.

The plasticizer component (C) used in the present invention
Is a mixture of process oil and partially hydrogenated triphenyl. Process oil is not hydrolyzed by wet heat,
Although it has excellent electrical insulation properties, the process oil alone lacks compatibility with the cured product of component (A) and component (B),
As a result, problems such as generation of bleed and lack of transparency occur. However, the above problems are avoided by a combination of partially hydrogenated triphenyl. Partially hydrogenated tri <br/> 5 to 1 phenyl for process oil 100 parts by weight
It is preferable to use 00 parts by weight, particularly 20 to 60 parts by weight.

The mixing ratio of the components (A) and (B) is such that the equivalent ratio of NCO to OH (NCO / OH) is 0.4 to 0.8, preferably 0.45 to 0.75. It is blended in. If it exceeds 0.8, the cured product has no tackiness, and its hardness is too high, so that when it is processed into a sheet, cracks are easily formed in the bent portion. On the other hand, if it is less than 0.4, it does not cure.

The component (C) is usually 50 to 300 parts by weight, especially 100 to 200 parts by weight, depending on the type of the urethane prepolymer, based on 100 parts by weight of the total of the components (A) and (B). It is preferable to mix parts.

As a catalyst for promoting the reaction between the hydroxyl group and the isocyanate group, an amine-based or metal compound-based curing catalyst used for producing polyurethane can be blended.

Preparation of admixtures Various methods are used for preparing admixtures. For example, the following method is typical. That is, the component (A) and the component (C)
This is a method in which a main agent containing the components is prepared, a curing agent containing the components (B) and (C) is separately prepared, and both are mixed at the time of construction to form a sheet or cast. In the preparation of the above-mentioned main ingredient, for example, when producing the component (A), after mixing the polyol component and the component (C), the mixture is reduced to 80 to 90 under reduced pressure.
After dehydration by heating to a temperature of 50 ° C., a method of adding an isocyanate component, heating and stirring at 50 to 60 ° C. to cause a reaction can be adopted. Further, the curing agent can be prepared by mixing the components (B) and (C), and then heating and dehydrating under reduced pressure.

Use of the admixture The admixture of the present invention is processed into a sheet and then wrapped and integrated with the entire connection portion of the communication cable using the adhesive force of the sheet, or by casting. Watertightness and airtightness of the connection part can be provided. Moreover, the construction is easy and the dismantling can be performed in a short time.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to specific embodiments. (Example 1) Poly MDI (NCO% 31.1) and MDI (NCO% 3
3.6) at 50 ° C. at a ratio of 6: 4 (N
CO% 32.1) 100 g and a diol having a number average molecular weight of 2,000 (polypropylene glycol having a hydroxyl value of 56)
30g and partially hydrogenated triphenyl (Thermo Ace 900 Nippon Steel Co., Ltd.) NCO% 6.9 and 315g and allowed 4 hours at 50 ° C., viscosity 230 cps / 25 ° C. of isocyanate prepolymer (1) Obtained. Molecular weight about 2800
-End hydroxylated polybutadiene (having a hydroxyl value of 46.6) 1
And 200 g, and castor oil (hydroxyl number 160) 50 g, and partially hydrogenated triphenyl 30g and purification process oil 220 g,
0.3 g of dibutyltin dilaurate was mixed as a catalyst to obtain a curing agent (2) having a viscosity of 400 cps / 25 ° C. The isocyanate prepolymer (1) and the curing agent (2) were stirred and mixed at an equivalent ratio (NCO / OH) of 0.73 to obtain an admixture of the present invention. Table 1 shows the compounding ratios in this case. The properties of the cured product were as follows: tensile strength 0.40 kgf / cm ² , elongation 320%, adhesive strength 3.0 g / 25 mm width, hardness 0, and volume resistivity 1.9 × 10 ¹⁴ Ω · cm. The characteristics are summarized in Table 2.

[0030]

[0031]

(Comparative Example 1) As an admixture for cable connection, there is already an SUD compound, which is obtained by reacting 100 g of castor oil (hydroxyl value 160) with 59 g of tolylene diisocyanate (80/20). 65 g of dioctyl sebacate was stirred and mixed with 100 g of isocyanate prepolymer (NCO% 10) (1). On the other hand, 73 g of castor oil, 9 g of epoxidized fatty acid ester and 0.35 g of tolylenediamine as a catalyst were added and stirred. Equivalent ratio (NCO / OH) of the obtained (2) isocyanate prepolymer (1) and curing agent (2)
The mixture was stirred and mixed at 1.05. The properties of this product were tensile strength 7 kgf / cm ² , elongation 70%, hardness 43, and volume resistivity 1.3 × 10 ¹³ Ω · cm. When the cured resin has a high hardness and is processed into a sheet shape, it is easily cracked when bent, and has no adhesive strength and is not suitable for use. Table 1 shows the composition and Table 2 shows the properties.

[0033]

[0034]

[0035]

[Table 1]

[0036]

[Table 2] In Table 2, each characteristic was measured according to the following method. Tensile strength: JIS K6301 Elongation: JIS K6301 Tear strength: JIS K6301 Hardness: JIS K6301 Adhesive strength: JIS K6301 Viscosity: B-type viscometer (25 ° C.) Volume specific resistance: JIS K 6911

The cured product must have a tensile strength of 0.3 kgf / cm ² or more, an elongation of 200% or more, an adhesive strength of 3 g / 25 mm or more, and a hardness (JIS A) of 0 or less. In addition, the volume resistivity is 10 as electric insulation.
It must be ¹³ Ω · cm or more. Further, it is desirable that the tensile strength be 3 kgf / cm ² or less from the viewpoint of ease of work during dismantling. It is clear from the results in Table 2 that the admixture of the present invention satisfies these conditions.

[0038]

EFFECTS OF THE INVENTION The admixture of the present invention is excellent in adhesiveness, electrical insulation and workability, has low toxicity, and can be easily and quickly disassembled and disassembled. Therefore, there are many health and safety and economic advantages, and the application effect is great.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // C09J 175/04 C09J 175/04 (72) Inventor Takeo Saito 1-6-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Telephone Co., Ltd. (56) References JP-A-63-34804 (JP, A) JP-A-63-6012 (JP, A) International Publication No. 92/7017 (WO, A1) (58) Fields investigated (Int. Cl. ^7, DB name) C09K 3/10 C08G 18/10 C08G 18/69 H01B 3/30 H02G 15/08 C09J 175/04

Claims (1)

(57) [Claims] 1. A compound having a number average molecular weight of 2,000 to 3,000.
Urethane prepolymer having terminal isocyanate groups (A), polybutadiene polyol and polybutadiene obtained by reacting an excess of polymethylene polyphenylene isocyanate alone or a mixed isocyanate obtained by adding 4,4'-diphenylmethane diisocyanate to a functional polyol 100 parts by weight of polyol
To number average molecular weight of 3,000 or less polyols and / or castor oil polyol component selected from the mixture formed by mixing polyol blend ratio of 60 parts by weight or less (B), and process oil and partially hydrogenated consisting triphenyl mixed plasticizer (C), and the mixing ratio of the urethane prepolymer (A) and the polyol component (B) is equivalent ratio (NCO / O
H) 0.4-0.8, the mixture for sealing a cable connection portion.