JPH04281320A - Spiral tube - Google Patents

Abstract

PURPOSE:To increase the impact resistance in a low temperature range by blending an anti-impact modifier (a mixture of chlorinated polyethylene and acrylate-group elastomer) with a mixture of post-chlorinated polyvinyl chloride and polyvinyl chloride by a specified ratio. CONSTITUTION:A spiral tube is composed of a resin formation wherein 14-17 pts.wt. of a mixture of 35-45wt.% of chlorinated polyethylene and 65-55wt.% of acrylate-group elastomer is blended as an anti-impact modifier, with 100 pts.wt. of a mixture of 80-90wt.% of post-chlorinated polyvinyl chloride and 20-10wt.% of polyvinyl chloride. Besides, the spiral tube has a forked shape and an inserting section 1, at one side edge, which has drawing-out-preventing sections 11 provided in a pair facing each other at the inner edges of an opening. A sashlike profile (MP) 5 having a hook section 2 which is hooked and checked by inserting into the inserting section 1 in a slidable state is made out of synthetic resin by profile extrusion. And, the MP 3 is wound into a spiral shape, and the inserting section 1 and hook section 2 adjoining each other are joined to form a tube.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spiral tube made of synthetic resin, and is suitably used as a protection tube for power cables, communication cables, etc. when these cables are buried underground.

0002

2. Description of the Related Art This type of protective tube is required to satisfy various physical properties such as compressive strength, tensile strength, impact resistance, heat resistance, and flame resistance in a well-balanced manner, and also to have good moldability.

[0003] In order to meet these demands, a cable protection tube has been proposed, for example, as disclosed in Japanese Patent Application Laid-Open No. 63-28219.

[0004] This protective tube is made of post-chlorinated polyvinyl chloride 7
Comprising 50 to 70 weight % of chlorinated polyethylene and 50 to 30 weight % of acrylate or methacrylate elastomer as an impact modifier to 100 parts by weight of a mixture of 0 to 90 weight % and 30 to 10 weight % of polyvinyl chloride. It is made by extrusion molding a resin composition containing 4 to 12 parts by weight of the mixture.

[0005] By the way, the above-mentioned protection pipe is a so-called straight pipe, but recently, flexible spiral pipes have been used to protect cables because of their adaptability to ground fluctuations after burial and their ease of construction. It has come to be used as a pipe.

[0006] This spiral tube has a fitting part on one side edge that is bifurcated and has a retaining part provided oppositely on the inner edge of the opening end, and a locking part that is slidably inserted and locked into the fitting part. For example, a band-shaped synthetic resin profile having a portion on the other side edge is
Using a pipe making machine such as that seen in Publication No. 3126, the pipe is wound spirally in a cold state, and the fitting part and the locking part which are adjacent to each other in the winding state are fitted to form a cylinder. It is something that is formed.

[0007] When such a spiral tube is used as a cable protection tube, it must satisfy the above-mentioned physical properties as in the case of a straight tube. Since it is formed by molding, stable moldability is also required. Furthermore, it must also have excellent surface properties so as not to damage the cable sheath during cable routing.

[0008] Therefore, it is expected that a satisfactory product will be obtained if the helical tube having the above structure is manufactured using a profile extruded from the resin composition used for the conventional protection tube (straight tube). .

[0009]

[Problems to be Solved by the Invention] However, when we actually evaluated various performances of spiral tubes made from synthetic resin profiles extruded from the resin composition, we found that the impact resistance, especially in the low temperature range, was It turned out to be inferior.

[0010] Here, impact resistance in a low temperature range means that even if a protection pipe is buried underground and a cable is inserted into it, the cable is not energized in winter and the thermal effect due to the heat generated by the cable is affected. For example, if excavation work is carried out near the place where the protection pipe is buried, or if the cable is left as an empty pipe without being inserted, it may be necessary to use a sharp construction tool such as a pickaxe to remove the cable. This is an evaluation method that assumes that unexpected shocks will be applied, and is one of the performance requirements for cable protection tubes.

As mentioned above, if the protective tube has poor impact resistance in a low temperature range, for example, if it is hit with a pickaxe, the sharp tip will cause a through hole or a hole in the inner peripheral surface of the tube wall. Cracks or protrusions occur. If such deformation occurs, the protection of the cable will be incomplete if the cable is inserted, and if the cable is not inserted, the cable and the above deformation will occur during subsequent cable insertion. This causes problems such as increased cable pull-in resistance or damage to the cable sheath.

[0012] In view of the above-mentioned problems, the present inventor has conducted extensive research with the aim of obtaining a helical tube that not only satisfies the above-mentioned physical properties but also has excellent impact resistance at low temperatures. As a result, the blending ratio of the impact modifier (mixture of chlorinated polyethylene and acrylate elastomer) to the mixture of post-chlorinated polyvinyl chloride and polyvinyl chloride determines the impact resistance at low temperatures. Based on this discovery, the present invention was completed.

[0013]

[Means for Solving the Problems] That is, the spiral tube according to the present invention can withstand 100 parts by weight of a mixture of 80 to 90% by weight of post-chlorinated polyvinyl chloride and 20 to 10% by weight of polyvinyl chloride. As an impact modifier, 35-45% by weight of chlorinated polyethylene and 65-5% by weight of acrylate elastomer.
The resin composition is made of a resin composition containing 14 to 17 parts by weight of a mixture of 5% by weight and 5% by weight. A band-shaped synthetic resin profile having a locking part on the other side edge that is slidably inserted and locked is formed by extrusion molding, and this profile is spirally wound. It is formed into a cylindrical shape by fitting a fitting part and a locking part.

The post-chlorinated polyvinyl chloride used in the present invention is produced by a conventionally known method, such as adding chlorine to polyvinyl chloride powder alone or in a state suspended in water together with a chlorinated hydrocarbon solvent. With something that
Preferably, the chlorine content is in the range of 60 to 70% by weight. If the chlorine content is less than 60% by weight, the heat resistance will deteriorate, and if it exceeds 70% by weight, the melt viscosity will be high and the processability will be poor.

The polyvinyl chloride used in the subsequent production of chlorinated polyvinyl chloride may be a homopolymer of vinyl chloride, or a vinyl chloride-based copolymer of vinyl chloride and other monomers copolymerizable. It may be a combination.

However, when using a copolymer, the content of other copolymerizable monomer units is preferably 15 parts by weight or less, preferably 6 parts by weight or less, per 100 parts by weight of vinyl chloride units. .

Examples of other copolymerizable monomers include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl laurate, acrylic esters such as methyl acrylate, ethyl acrylate, and butyl acrylate, methyl methacrylate, and ethyl acrylate. Methacrylic acid esters such as methacrylate, maleic acid esters such as dibutyl maleate and diethyl maleate, fumaric acid esters such as dibutyl fumarate and diethyl fumarate, vinyl ethers such as vinyl methyl ether, vinyl butyl ether, and vinyl octyl ether. , vinyl cyanides such as acrylonitrile and methacrylonitrile, olefins such as ethylene, propylene and n-butene, vinylidene halides other than vinyl chloride such as vinylidene chloride and vinyl bromide, or vinyl halides. .

The polyvinyl chloride used in the present invention is produced by a conventionally known method such as a suspension polymerization method or an emulsion polymerization method. Among these, those having an average degree of polymerization of 800 to 1,500 are preferred. If the average degree of polymerization is less than 800, the impact resistance will be poor, and if it exceeds 1500, the melt viscosity will be high and the processability will be poor.

The chlorinated polyethylene used in the present invention preferably has a chlorine content of 20 to 45% by weight, more preferably 30 to 40% by weight. In addition, non-crystalline materials or materials with a small amount of crystalline portion are preferable.

The acrylic elastomer used in the present invention is, for example, methyl methacrylate, butadiene,
It is made of at least one of a styrene-based graft polymer and an acrylate-based rubber graft polymer, and is produced by a conventionally known method.

[0021] The above methyl methacrylate/butadiene/
A styrenic graft polymer is a multicomponent resin obtained by graft polymerizing methyl methacrylate, styrene, etc. to a rubber whose main component is butadiene.

Examples of the graft polymer of the acrylate rubber include those disclosed in JP-A-51-5674, JP-A-51-129449, or JP-B-Sho 52-36.
Examples include multi-component resins described in Publication No. 67 and the like.

Among the above-mentioned acrylic elastomers, terpolymer rubber with butadiene and methyl methacrylate mainly composed of alkyl acrylate (acrylic acid alkyl ester is 75% by weight or less) and acrylonitrile, methyl methacrylate, styrene, etc. are used. Additive polymerized multicomponent resins are preferred.

[0024] As mentioned above, the mixing ratio of post-chlorinated polyvinyl chloride and polyvinyl chloride in the present invention is 80-90% by weight of post-chlorinated polyvinyl chloride and 20-10% by weight of vinyl chloride. The range of

If the proportion of post-chlorinated polyvinyl chloride is less than 80% by weight, sufficient heat resistance cannot be obtained, and if it exceeds 90% by weight, satisfactory impact resistance and processability cannot be obtained.

[0026] In the present invention, the impact modifier blended into the mixture of post-chlorinated polyvinyl chloride and polyvinyl chloride is a mixture of chlorinated polyethylene and acrylate elastomer, and the mixing ratio thereof is chlorine. The content of the acrylate elastomer is 35 to 45% by weight and 65 to 55% by weight of the acrylate elastomer.

[0027] If the proportion of chlorinated polyethylene is less than 35% by weight, it cannot have a positive effect on improving impact resistance and processability. Moreover, if it exceeds 45% by weight, it becomes difficult to suppress a decrease in tensile strength and improve impact resistance.

The impact modifier is blended in an amount of 14 to 17 parts by weight based on 100 parts by weight of the mixture of the post-chlorinated polyvinyl chloride and polyvinyl chloride.

[0029] If the blending ratio of the impact modifier is less than 14 parts by weight, the impact resistance, particularly in the low temperature range, will be poor. Moreover, if it exceeds 17 parts by weight, it causes a decrease in tensile strength, heat resistance, etc.

The resin composition of the present invention may contain appropriate amounts of auxiliary materials such as stabilizers, lubricants, antioxidants, ultraviolet absorbers, fillers, and pigments, if necessary.

[0031] The helical tube of the present invention can be prepared from the above resin composition by:
It has a bifurcated shape as shown in FIG. 2 and has a retaining part 11 on the inner edge of the opening end.
. The profile 3 is formed by extrusion molding into a profile, and is spirally wound in a cold state at about 10 to 50°C using a pipe making machine, and the fitting part 1 and the locking part 2 that are adjacent to each other are fitted in the rolled state. Together, they are formed into a cylindrical shape (see Figure 1).

The spiral tube manufactured in this manner differs from the conventional protection tube (straight tube) described above in the following points.

■ In the spiral tube of the present invention, the resin located on the outer circumferential surface of the tube is pulled in the circumferential direction of the tube, and the resin located on the inner circumferential surface is compressed in the circumferential direction, whereas in the conventional In a straight pipe, the resin on both the inner and outer circumferential surfaces is usually stretched in the radial direction of the pipe.

■ In the helical tube of the present invention, the impact modifier is oriented in the circumferential direction of the tube, whereas in the conventional straight tube, it is oriented in the axial direction of the tube.

[0035]

[Example] For Examples 1 to 3 of the present invention, resin compositions each having a predetermined amount (parts by weight) of the compounding ratio shown in Table 1 were prepared, and the average wall thickness (indicated by the symbol t in FIG. 2) was prepared from the resin compositions. A profile with a diameter of 3.7 mm and a unit weight of 350 g/m was extruded.

From this profile, a spiral tube having an outer diameter of 157 mm, an inner diameter of 130 mm, a tube weight of 6.5 kg/m, and a minimum bending radius of 4000 mmR was fabricated using a pipe making machine in a cold state.

Comparative Examples 1 to 5 to be compared with this example
Resin compositions having the predetermined amounts (parts by weight) shown in Table 2 were also prepared, and spiral tubes were made from the resin compositions in the same manner as in this example.

The post-chlorinated polyvinyl chloride used was Nikatemp T-961 (chlorine content 66%, average degree of polymerization 1050) manufactured by Nippon Carbide Co., Ltd., and the polyvinyl chloride used was P=1400 manufactured by Tokuyama Sekisui Co., Ltd. As the chlorinated polyethylene, Daisolac H manufactured by Osaka Soda Co., Ltd.
-135 (chlorine content: 35%) and Kane Ace FM manufactured by Kanebuchi Chemical Co., Ltd. were used as the acrylate elastomer.

The physical properties of each helical tube produced as described above were evaluated using the methods listed below. The results are shown in Tables 1 and 2.

■Impact Resistance Pass Rate A load of 16.16 kg with a pickaxe-shaped tip is attached to the tip of a rotatable arm with a length of 1 m, and the load is allowed to fall naturally from an angle of 95 degrees to a temperature of 0°C in advance. and 80° C., and the occurrence of through holes, cracks, protrusions, etc. in the inner resin layer of the tube was observed.

■ 80°C Compression Deformation A 150mm long tube heated to 80°C is compressed at a speed of 10mm/min in the direction perpendicular to the tube axis, resulting in 64.8kg.
The amount of flattening of the tube when a load of f/150 mm was applied was measured.

[0042] Vicat Softening Temperature The softening temperature was carried out under a load of 5 kgf according to JIS K 7206.

■20℃ tensile strength 20℃, 10mm/m according to JIS K 7113
It was carried out at a tensile speed of in.

[0044] Weather resistance After exposing the test piece for 100 hours according to JIS A 1415, Charpy impact strength was measured at 23°C according to JIS K 7111.

■Appearance The smoothness of the inner and outer surfaces of the tube was visually observed.

■Dimensions The dimensional accuracy of the tube was measured using a tape measure.

■ Cut a test piece about 40 mm wide and about 50 mm long from the flame-resistant tube, attach one end of this to a stand, place a Bunsen burner with a flame of about 15 mm under the free end of the test piece, and set the flame The tip of the test piece was allowed to reach the bottom edge of the test piece, and the test piece was left for 1 minute. After 1 minute had elapsed, the flame of the burner was removed, and it was observed whether the flame of the test piece disappeared naturally.

In Tables 1 and 2, the required performances in the right column are the lower limits of each performance required of the helical tube as a cable protection tube.

[0049]

[Table 1]

[0050]

[Table 2]

[0051] As is clear from Tables 1 and 2 above,
The spiral tubes of this example all satisfy all of the performance requirements for cable protection tubes, whereas the spiral tubes of comparative examples whose blending ratio of impact modifier is not within the range of the present invention are It also has poor impact resistance.

[0052]

[Effects of the Invention] The spiral tube of the present invention satisfies various physical properties such as compressive strength, tensile strength, impact resistance, heat resistance, and flame resistance in a well-balanced manner. Excellent impact resistance in the area.

Therefore, even if an unexpected impact is applied by a construction tool with a sharp tip, such as a pickaxe, in a low temperature range, specifically 0°C, there will be no through holes, cracks, or protrusions on the inner peripheral surface of the pipe wall. This ensures that the cable is protected, and if the cable is to be pulled in later, there will be no increase in cable pull-in resistance, and there will be no damage to the cable sheath. There is no fear that it will.

Moreover, since the spiral pipe of the present invention has stretchability and flexibility, it can respond to ground fluctuations.
Not only can the cable be protected underground for a long period of time, but it can also be used in places where the cable is bent, and has good workability.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing a spiral tube according to the present invention.

FIG. 2 is an enlarged partial perspective view of a synthetic resin profile.

[Explanation of symbols]

1 Fitting part 11 Retaining part 2 Locking part 3 Synthetic resin profile

Claims (1)

[Claims] Claim 1: A mixture of 80-90% by weight of post-chlorinated polyvinyl chloride and 20-10% by weight of polyvinyl chloride 10
0 parts by weight, 35 to 45% by weight of chlorinated polyethylene and acrylate elastomer 6 as impact modifiers.
The resin composition is made of a resin composition containing 14 to 17 parts by weight of a mixture of 5 to 55% by weight, and has a fitting part on one side edge that is bifurcated and has a retaining part opposite to the inner edge of the opening end. A band-shaped synthetic resin profile having a locking part on the other side edge that is slidably inserted and locked into the joint part is extruded into a profile, and this profile is wound in a spiral shape, and in the wound state, it is placed adjacent to each other. A spiral tube formed into a cylindrical shape by fitting the fitting part and the locking part.