JP2016037570A - Chloroprene rubber composition and manufacturing method therefor, and wire and cable - Google Patents

Abstract

Provided are a chloroprene rubber composition capable of sufficiently suppressing foaming even when crosslinked under normal pressure, a method for producing the same, and an electric wire and cable.
A rubber material is extruded while being deaerated by a two-stage vent type extruder, and the extruded rubber material is continuously passed through an atmospheric pressure crosslinking equipment to be crosslinked. A cable 6 covered with a sheath made of a chloroprene rubber composition having a moisture content determined in accordance with JIS K 0113 of 0.20% by mass or less and a diameter of a void present in the composition of 20 μm or less.
[Selection] Figure 3

Description

  The present invention relates to a chloroprene rubber composition, a method for producing the same, and an electric wire and a cable using the chloroprene rubber composition.

  Insulating wire / cable coating materials include microwave crosslinking (UHF), molten salt crosslinking (LCM), saturated steam continuous crosslinking (SVCV), superheated steam continuous crosslinking (SSSCV), and far-infrared continuous crosslinking (IRCV). , Continuous cross-linking methods such as fluidized bed method (PCM), hot air heating method (HAV), electron beam irradiation method, etc., lead, TPX (trimethylpentene), etc. are covered on wires / cables and wound around a drum. There is a batch crosslinking method for crosslinking.

  Which of these crosslinking methods is most suitable is selected and applied depending on the thickness, shape, structure, length, type of coating material, and the like of the object to be crosslinked.

  These crosslinking methods have advantages and disadvantages from the viewpoints of crosslinking equipment price, crosslinking speed, handleability, product performance, etc., but the continuous crosslinking method is excellent in terms of productivity and suppression of deformation during drum winding. In addition, atmospheric pressure crosslinking is superior in that it does not require pressure equipment costs and can suppress deformation during crosslinking. Therefore, it can be said that the continuous atmospheric pressure crosslinking method is most excellent in terms of productivity, equipment cost, and cable deformation suppression.

  Among the continuous atmospheric pressure crosslinking methods, the fluidized bed method (PCM) and the hot air heating method (HAV) are methods of crosslinking by heating through a tube heated to a high temperature under normal pressure. The former has glass beads, but mainly has air heat transfer, so that the heat transfer characteristics to the cross-linking object are poor and the production speed is slow.

  The electron beam irradiation method is generally suitable for manufacturing a thin insulated wire rather than a thick insulated wire because the penetration thickness into the material is limited by the strength of the electron beam. Also, since the extrusion process and the irradiation process are separate processes, it is necessary to take up the drum once. In that case, there is a problem that the uncrosslinked coating material is subject to deformation, so the insulating material is difficult to deform at room temperature. It is limited to.

  In the case of other continuous atmospheric pressure crosslinking methods, there is a drawback that foaming occurs due to heating exceeding 100 ° C.

  The cause of foaming due to heating exceeding 100 ° C. is considered to be caused by moisture and bubbles contained in the material, and Patent Document 1 proposes that the moisture content in the chloroprene rubber composition be 0.25% or less. Has been.

JP 2013-23518 A (Claim 4)

  However, in practice, there is a problem that foaming at the time of crosslinking under normal pressure cannot be suppressed only by controlling the amount of water.

  Then, the objective of this invention is providing the chloroprene rubber composition which can fully suppress foaming even if bridge | crosslinking under a normal pressure, its manufacturing method, an electric wire, and a cable.

  In order to achieve the above object, the present invention provides the following chloroprene rubber composition and method for producing the same, as well as electric wires and cables.

[1] Moisture content determined according to JIS K 0113 (measurement temperature: 130 ° C., measurement time: until the drift value returns to the initial drift value +0.1 μg / s, the moisture content value: less than the decimal point in% units A chloroprene rubber composition in which the third digit is rounded down) is 0.20% by mass or less, and the diameter of voids present in the composition is 20 μm or less.
[2] The chloroprene rubber composition according to the above [1], which has been deaerated by being extruded by a two-stage vent type extruder.
[3] The chloroprene rubber composition according to [1] or [2], which is obtained by extrusion molding using a rubber material stored at 40 ° C. or less and 20 RH% or less.
[4] The chloroprene rubber composition according to any one of the above [1] to [3], which is obtained through a step of continuously heating and crosslinking under normal pressure after extrusion.
[5] The chloroprene rubber composition according to [4], wherein the normal pressure is less than 0.2 MPa.
[6] An electric wire having an insulating layer made of the chloroprene rubber composition according to any one of [1] to [5].
[7] A cable having an insulating layer and / or a sheath made of the chloroprene rubber composition according to any one of [1] to [5].
[8] A chloroprene, wherein a rubber material is extruded while being deaerated by a two-stage vent type extruder, and the extruded rubber material is crosslinked by continuously passing through an atmospheric pressure crosslinking facility. A method for producing a rubber composition.
[9] The crosslinking method in the atmospheric pressure crosslinking equipment is microwave crosslinking (UHF), molten salt crosslinking (LCM), saturated steam continuous crosslinking (SVCV), superheated steam continuous crosslinking (SSSCV), far infrared continuous crosslinking (IRCV). Or the method for producing a chloroprene rubber composition as described in [8] above, which is a warm bath of 90 ° C. or higher.

  ADVANTAGE OF THE INVENTION According to this invention, even if it bridge | crosslinks under a normal pressure, the chloroprene rubber composition which can fully suppress foaming, its manufacturing method, an electric wire, and a cable can be provided.

It is a figure which shows the manufacture example of the chloroprene rubber composition which concerns on embodiment of this invention. It is a cross-sectional view showing an example of a cable according to an embodiment of the present invention. It is a figure which shows the manufacture example of the cable which concerns on embodiment of this invention.

[Chloroprene rubber composition]
The chloroprene rubber composition according to the embodiment of the present invention has a moisture content determined in accordance with JIS K 0113 of 0.20% by mass or less, and a void diameter (diameter) present in the composition of 20 μm or less. is there. If the water content exceeds 0.20 mass%, or voids having a diameter exceeding 20 μm are present in the composition, foaming cannot be sufficiently suppressed when crosslinked under normal pressure.

  As a rubber material of the chloroprene rubber composition, a commercially available polychloroprene rubber (CR) can be used. General compounding agents such as various crosslinking agents, plasticizers, lubricants, fillers, flame retardants, and colorants may be added to the chloroprene rubber composition.

FIG. 1 is a diagram showing a production example of a chloroprene rubber composition according to an embodiment of the present invention.
The chloroprene rubber composition according to the above-described embodiment of the present invention can be obtained through a process of deaeration treatment by extrusion with the two-stage vent type extruder 11.

  The two-stage vent type extruder 11 uses a two-stage screw provided with a slow compression part in the middle part of the screw and a vent hole in the middle part of the cylinder, and eats together with the extruded material by vacuum suction or atmospheric discharge from this hole. It removes moisture and volatiles in the air and materials that are introduced, and improves the quality of the extruded product.

  As shown in FIG. 1, a chloroprene rubber composition 10 obtained by mixing materials is extruded from a two-stage vent-type extruder 11 and supplied to a pelletizer 12, and the chloroprene rubber composition according to the embodiment of the present invention. To a pellet 20 made of

  The chloroprene rubber composition 10 before extrusion molding is preferably stored at 40 ° C. or lower and 20 RH% or lower. More preferably, it is 30 ° C. or lower and 10 RH% or lower. Storage in an environment of 40 ° C. or lower and 20 RH% or lower before extrusion can prevent the chloroprene rubber composition 10 from absorbing moisture. Moreover, it is desirable to store the obtained pellets 20 in the above environment.

  The chloroprene rubber composition according to the embodiment of the present invention is preferably obtained through a step of crosslinking by continuous heating under normal pressure after extrusion molding. The normal pressure is preferably less than 0.2 MPa.

  The step of continuously heating and crosslinking under normal pressure is a step of crosslinking by, for example, continuously passing the rubber material extruded by the above-described two-stage vent type extruder through a normal pressure crosslinking facility. It is preferable. The atmospheric pressure crosslinking equipment is preferably connected to the two-stage vent type extruder.

  As the crosslinking method in the atmospheric pressure crosslinking equipment, microwave crosslinking (UHF), molten salt crosslinking (LCM), saturated steam continuous crosslinking (SVCV), superheated steam continuous crosslinking (SSCV), far infrared continuous crosslinking (IRCV), or 90 It is preferable that it is a warm bath above ℃.

[Wire / Cable]
The electric wire which concerns on embodiment of this invention has an insulating layer which consists of the said chloroprene rubber composition which concerns on embodiment of this invention, It is characterized by the above-mentioned. Moreover, the cable which concerns on embodiment of this invention has the insulating layer and / or sheath which consist of the said chloroprene rubber composition which concerns on embodiment of this invention, It is characterized by the above-mentioned.

The electric wire and cable according to the embodiment of the present invention will be described in more detail with reference to the drawings.
FIG. 2 is a cross-sectional view showing an example of a cable according to the embodiment of the present invention.

  The electric wire 3 according to the present embodiment includes a conductor 1 made of a general-purpose material, for example, pure copper or tin-plated copper, and an insulator 2 coated on the outer periphery of the conductor 1. The insulator 2 is comprised from said chloroprene rubber composition which concerns on embodiment of this invention. The number of conductors 1 is not limited to one, and a plurality of strands may be twisted.

  The electric wire 3 which concerns on this Embodiment is used as a component of the cable 20 which concerns on this Embodiment, for example, as shown in FIG.

  The cable 20 according to the present embodiment includes a twisted core 4 in which three electric wires 3 are twisted together, and a sheath 5 that is extrusion-coated on the outer periphery of the twisted core 4. The electric wire 3 may be a single core or a multi-core stranded wire other than a three-core.

  In the cable 20 according to the present embodiment, only the insulator 2 or the sheath 5 may be composed of the chloroprene rubber composition according to the embodiment of the present invention. It is preferable that both 2 and the sheath 5 are composed of the above chloroprene rubber composition. When the chloroprene rubber composition is not used, ethylene propylene rubber or the like can be used for the insulator 2 or the sheath 5.

  In the present embodiment, the sheath may be composed of a single layer or a multilayer structure. Further, a separator, a braid, a shield tape made of metal foil, or the like may be applied as necessary.

  FIG. 3 is a diagram showing a manufacturing example of the cable according to the embodiment of the present invention. According to the production line shown in FIG. 3, it is possible to produce a cable having a sheath in which foaming is sufficiently suppressed even when crosslinked under normal pressure.

  First, the chloroprene rubber composition 10 is extruded by a two-stage vent-type extruder 11 and coated on the outer periphery of the twisted core 4 in a cross head, and then continuously subjected to a crosslinking treatment by an atmospheric pressure crosslinking facility 13. Then, it cools in the water cooling zone 14, and the cable 6 coat | covered with the sheath 5 comprised from the said chloroprene rubber composition which concerns on embodiment of this invention is wound around the winding drum 15. FIG.

  When the extrusion temperature in the two-stage vent type extruder 11 is set to 80 ° C. or higher, the time for raising the temperature of the coating material to a predetermined crosslinking temperature in the atmospheric pressure crosslinking equipment 13 can be suppressed as short as possible.

  The extrusion temperature of the two-stage vent type extruder 11 is preferably 80 ° C. or higher and 100 ° C. or lower. When the extrusion temperature exceeds 100 ° C., pre-crosslinking before cross-linking by the atmospheric pressure cross-linking equipment 13 proceeds excessively, and a part of the viscosity increases, which may cause appearance defects such as “crushing” and “blowing”. is there.

  In the normal pressure crosslinking equipment 13, the coating material is heated under normal pressure to crosslink the coating material. By heating the coating material under normal pressure, deformation of the material during crosslinking can be prevented. The crosslinking method in the atmospheric pressure crosslinking facility is as described above.

  It is desirable to attach a guide roll or the like to the bottom of the atmospheric pressure crosslinking equipment 13 in order to prevent deformation and scratches of the unvulcanized coating material.

  Although not shown, the production line of FIG. 3 can be provided with necessary equipment such as a core wire / core feeding machine, a product winder, an outer diameter measuring instrument, and an accumulator.

  The target products include electric wires and cables, but can also be applied to various other products such as solid extruded products including atypical shapes, hoses and the like. The latter two are particularly suitable for structures that contain linear metal wires or metals inside, or that contain a type of knitted natural / synthetic polymer yarn.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

  The pellet 20 in FIG. 1 and the cable 6 having the structure in FIG. 2 were manufactured by the following method, and measurement and evaluation were performed.

The size of each part of the cable (electric wire: 3 × 22 mm ² ) is as follows.
Conductor configuration (outer diameter / number / element diameter): 7 mm / 20 lines / 0.45 mm
・ Outer diameter: 7mm,
・ Insulator thickness: 1.2 mm
-Sheath thickness: 2.7 mm
-Finished outer diameter: 26mm

  The electric wire 3 was obtained by extruding and covering each color (red, white, black) of sulfur-crosslinked EPR (ethylene propylene rubber) as an insulator 2 on the conductor 1 to a predetermined thickness, and then crosslinking with pressurized steam.

  These three (each color) electric wires 3 were twisted to obtain a twisted core 4. The outer periphery of the twisted core 4 is extrusion coated with a polychloroprene sheath material (CR-1 or CR-2) shown in Table 1 by a two-stage vent type extruder 11 at a speed of 5 m / min. After cross-linking, the cable 6 was cooled with water. The sheath material was crosslinked by molten salt crosslinking (LCM) at normal pressure (0.1 MPa). The crosslinking condition is 200 ° C. × 10 min.

  Table 2 shows the conditions of extrusion by the two-stage vent-type extruder 11 (hereinafter sometimes referred to as “two-stage vent extrusion”). The material size in the vent chamber of the two-stage vent type extruder 11 was adjusted to about 1 mm by adjusting the extrusion speed and the number of revolutions of the cutter, and the vacuum degassing was performed under the condition of 0.09 MPa. In Examples 1 to 3 and Comparative Examples 1 and 3, the polychloroprene sheath material was stored at 20 ° C and 5RH% corresponding to 40 ° C or less and 20RH% or less until use. Then, it was left at room temperature and humidity until it was used.

  For Examples 1 and 2 and Comparative Examples 1 and 2, pellets were prepared using the equipment shown in FIG. 1 and used as samples to be evaluated. However, in the evaluation of the presence or absence of foaming in the material after the crosslinking treatment, as described later, these uncrosslinked pellets were subjected to a crosslinking treatment by LCM. LCM was performed at normal pressure (0.1 MPa).

  For Example 3 and Comparative Example 3, as described above, a cable product (3 PNCT) was produced using the equipment shown in FIG. 3, and these were used as samples to be evaluated. However, the sample used for the moisture content measurement and void observation of the extruded material was not a cable shape but a material extruded in a tube shape from an extruder in order to evaluate the state before crosslinking.

  The contents of measurement and evaluation are as follows.

(1) Moisture content of extruded material
In accordance with JIS K 0113, the moisture content of the extruded material was quantified with a Karl Fischer moisture meter MKC-610 (manufactured by Kyoto Electronics Industry). The sample mass is about 3 g, and the sample shape is the measurement sample as it is in the case of pellets. In the case of Example 3 and Comparative Example 3, the material extruded in the tube shape is cut into small pieces with a cutter and pressed at 40 ° C. (preheating) After forming into a sheet having a thickness of 2 mm in 2 minutes and pressurizing for 1 minute, a measurement sample was formed into a pellet shape of φ3 mm with a punch jig. The measurement temperature is 130 ° C, and the measurement time is until the drift value (the amount of moisture in the air entering the titration cell or the amount of moisture contained in the carrier gas) returns to the initial drift value + 0.1 μg / s. did. In addition, the water | moisture-content fixed value was made into 2 digits below a decimal point, and it cut off after the 3rd digit.

(2) Observation of Void in Extruded Material Uncrosslinked extruded pellets and extruded tube material, and a razor were stored in a refrigerator at 3 ° C. for 30 minutes to increase the hardness of the material, and then the material was cut with a razor. The cut surface was observed with an electron microscope (SEM), and the presence or absence of voids having a diameter exceeding 20 μm was examined. In addition, if it does not exist in one arbitrary cross section, the probability that it does not exist in the whole is very high, and it can be said that the requirement of the present invention is satisfied.

(3) Presence / absence of foaming in material after cross-linking treatment After cross-linking treatment under conditions of 200 ° C. × 10 min by LCM, the sample was cut with a cutter, and the presence or absence of foaming on the cut surface was observed. In addition, if it does not exist in one arbitrary cross section, the probability that it does not exist in the whole is very high, and it can be said that the effect of the present invention is exhibited.

  Table 2 shows the measurement and evaluation results of Examples 1 to 3 and Comparative Examples 1 to 3.

  In Examples 1 to 3, the sheath material (CR-1, CR-2) is a standard chloroprene rubber, which has been subjected to deaeration treatment at the time of two-stage vent extrusion. The voids were 0.20% by mass or less, and no voids having a diameter exceeding 20 μm were found in the material. No foaming was observed in any observation after the crosslinking treatment.

  In contrast, Comparative Examples 1 and 3 were not degassed during the two-stage vent extrusion, and the water content was 0.20% by mass or less, but voids having a diameter exceeding 20 μm were observed in the material. It was done. In all of the observations after the crosslinking treatment, foaming was observed.

  In Comparative Example 2, although the deaeration treatment was performed during the two-stage vent extrusion, the moisture content of the extruded material was 0.21% by mass, and no voids having a diameter exceeding 20 μm were found in the material. Foaming was observed in the observation after the treatment.

  From the above, by setting the water content of the chloroprene rubber composition to 0.20% by mass or less and the diameter of the voids present in the composition to 20 μm or less, pellets and cables that do not cause foaming even under a crosslinking treatment under normal pressure are obtained. be able to.

  In addition, this invention is not limited to the said embodiment and Example, A various deformation | transformation implementation is possible.

1: conductor, 2: insulator, 3: electric wire, 4: twisted core, 5: sheath 6: cable, 10: chloroprene rubber composition (material), 20: pellet 11: two-stage vent type extruder, 12: Pelletizer, 13: Atmospheric pressure crosslinking equipment, 14: Water cooling zone, 15: Winding drum

Claims (9)

  Moisture content quantified according to JIS K 0113 (measurement temperature: 130 ° C., measurement time: until the drift value returns to the initial drift value +0.1 μg / s, the moisture content value: the third digit below the decimal point in% units A chloroprene rubber composition having a value of 0.20% by mass or less) and a void diameter in the composition of 20 μm or less.   The chloroprene rubber composition according to claim 1, wherein the chloroprene rubber composition has been degassed by being extruded by a two-stage vent type extruder.   The chloroprene rubber composition according to claim 1 or 2, wherein the chloroprene rubber composition is obtained by extrusion molding using a rubber material stored at 40 ° C or lower and 20RH% or lower.   The chloroprene rubber composition according to any one of claims 1 to 3, wherein the chloroprene rubber composition is obtained through a step of cross-linking by continuous heating under normal pressure after extrusion molding.   The chloroprene rubber composition according to claim 4, wherein the normal pressure is less than 0.2 MPa.   The electric wire which has an insulating layer which consists of a chloroprene rubber composition of any one of Claims 1-5.   The cable which has an insulating layer and / or sheath which consist of a chloroprene rubber composition of any one of Claims 1-5.   A chloroprene rubber composition characterized in that a rubber material is extruded while being degassed by a two-stage vent type extruder, and the extruded rubber material is continuously cross-linked by passing it through an atmospheric pressure crosslinking facility. Manufacturing method. The crosslinking method in the atmospheric pressure crosslinking equipment is microwave crosslinking (UHF), molten salt crosslinking (LCM), saturated steam continuous crosslinking (SVCV), superheated steam continuous crosslinking (SSCV), far infrared continuous crosslinking (IRCV), or 90 The method for producing a chloroprene rubber composition according to claim 8, wherein the chloroprene rubber composition is a warm bath of at least ° C.

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