JPH0218033A - Manufacturing method of mandrel for horse manufacture - Google Patents

Abstract

PURPOSE:To improve the property of an outer flaw resistance and advance the property of a repeating use by bridging the surface in irradiation-processing a mandrel for manufacturing a horse consisting of poly-4-methylpentene-1. CONSTITUTION:A mandrel consisting of poly-4-methylpentene-1 is bridged by being irradiated in its surface. The bridge formation of the surface is performed by which a conventional poly-4-methylpentene-1 mandrel is irradiated with ultra-violet rays by an electron beam, however, in order to perform it effectively, a mandrel is formed by the use of a composition wherein a functional monomer is admixed to the poly-4-methylpentene-1 in an amount of 0.1-15pts.wt. per 100pts.wt., subsequently, irradiating it or applying the functional monomer on the surface of the poly-4-methylepenten-1 mandrel, preferably, diffusely impregnating it thereinto, and irradiating them in the next place, the formation is achieved. Thus, the property of outer flaw resistance is improved considerably in performing a bridge formation to only its surface.

Description

[Detailed Description of the Invention] The present invention relates to a method for manufacturing a mandrel for manufacturing hoses, and particularly a method for manufacturing a mandrel for manufacturing hoses made of surface-modified poly-4-methylpentene-1. Regarding.

Conventionally, plastic mandrels made of cross-linked polyethylene, polypropylene, nylon, various polyesters, etc. have been used as mandrels for manufacturing hoses.

When manufacturing a hose using a plastic mandrel, unvulcanized rubber or plastic is extruded onto the mandrel to form a layer that will become the hose, and then the unvulcanized rubber or plastic layer on the mandrel is heated and vulcanized. After this, the plastic mandrel is cooled and finally the plastic mandrel is pulled out or extruded to separate the vulcanized layer (ie, hose) from the mandrel.

However, conventionally used plastic mandrels have various drawbacks and are not necessarily satisfactory.

For example, nylon mandrels and polyester mandrels have an extremely high water absorption rate, so their outer diameter increases due to water absorption, or when heated to high temperatures during vulcanization, the absorbed moisture is emitted and the vulcanized layer (hose body) This causes problems such as making the inner diameter non-uniform and forming voids within the layer. For this reason, it is necessary to heat and dry the mandrel before use. These mandrels are also
It hydrolyzes with water and its surface gradually becomes rough, so its lifespan after repeated use is extremely short.

On the other hand, crosslinked polyethylene mandrels and polypropylene mandrels have the disadvantage of poor high temperature dimensional stability and often deformation when heated to vulcanization temperatures. Therefore, the present inventors previously proposed a mandrel made of poly-4-methylpentene I as a mandrel free from the above-mentioned problems found in conventionally known plastic mandrels.

Since poly-4-methylpentene-1 is a substance with low polarity and a high melting point, it has extremely low water absorption and also has excellent high-temperature dimensional stability. Therefore, the mandrel made of the polymer has the excellent advantage of not having problems such as an increase in outer diameter due to water absorption, drying by heating before use, or surface roughening due to hydrolysis.

By the way, poly-4-methylpentene-1 mandrels generally have a problem in that their surface has low trauma resistance.On the other hand,
In the final process of manufacturing hoses, the mandrel is separated from the vulcanized hose by drawing or extrusion, but in industrial-scale hose production, this mandrel separation process is done quite roughly, so polyester is used. -4-Methylpentene-1 There is a problem in that the mandrel has scratches on its surface due to friction with the flooring of the workplace, etc. 0 A high-quality hose cannot be manufactured using a mandrel with scratches on its surface.

In order to solve the above-mentioned problems, the present invention is characterized in that a hose manufacturing mandrel made of poly-4-methylpentene-1 is irradiated to crosslink its surface. The present invention aims to provide a method for manufacturing a mandrel for manufacturing hoses.

■The surface of the six-fruited poly-4-methylpentene-1 mandrel is crosslinked by irradiation, improving its resistance to external forces and making it difficult for scratches to occur on the surface even when the mandrel is separated. , repeatability is improved.

Specific 3B of 1 As poly-4-methylpentene-1 used in the present invention, homopolymers and copolymers of 4-methylpentene-1 are used. Examples of such polymers include AST
M D 1238-70 (260°C, 5 kg) with a melt index of 1-100, especially 5-8
0, and the density of 23"C is about 0.82 to 0.85. There is a crystalline polymer having stereoregularity.Poly-4-
Methylpentene-1 is 4 methylpentene-1 only,
Alternatively, it is produced by a method such as polymerization using a Ziegler type catalyst together with the copolymerization components described below. Copolymerization components include ethylene, propylene, butene, pentene, hexene, octene, 3-methyl-butene-1,3-methyl-pentene-1,4,4"-dimethylpentene-1
, linear or branched aliphatic hydrocarbon vinyl compounds such as 3-methyl-hexene-1, styrene, orthodivinylbenzene, metadivinylbenzene, varadivinylbenzene, metadivinyltoluene, paradivinyltoluene, α
- Aromatic hydrocarbon vinyl compounds such as methylstyrene can be exemplified. The copolymerization component may be one type or two or more types. The poly-4-methylpentene-1 used in the present invention is preferably one containing at least 60% by weight of the 4-methylpentene-1 component. is preferred. Aromatic hydrocarbon vinyl compound components from 0.1 to
One containing 20% by weight is also one of the preferable ones.

Apart from the poly-4-methylpentene-1 and its copolymer, a compatible polymer or liquid may be added as a plasticizer in order to give them further flexibility.

The amount added is preferably 30% by weight or less since it is necessary to maintain the high-temperature shape retention of poly-4-methylpentene-1. Particularly preferred plasticizers have molecules 11,300 to 5
,000 α-olefin oligomers and polybutenes.

Furthermore, it is also possible to add a small amount of oxidation stabilizer or the like to extend the life of the mandrel.

The mandrel to be subjected to the irradiation treatment described later in the present invention is
A long body with a circular cross section is obtained by extrusion coating the poly-4-methylpentene-1 on a reinforcing body made of twisted wires or single wires made of various metals such as iron, steel, aluminum, copper, etc. This is a typical example. The cross-sectional shape of the mandrel may be circular, oval, or any other shape depending on the cross-sectional shape of the hose desired to be manufactured.

After the vulcanization process in hose production, the mandrel is pulled out, but the longer the hose being manufactured, the more difficult it is to pull out the mandrel, even if a lubricant or mold release agent is applied to the surface of the mandrel. Since this requires a large amount of force and there is a possibility of the mandrel being cut, it is preferable in the present invention to use a reinforcing body built-in. In particular, incorporating twisted wires is preferable because it hardly changes the flexibility of the mandrel. However, such a reinforcing member is not necessary when no tension is applied to the mandrel, such as when water pressure is applied to one end of the hose and the mandrel is pushed out and separated by the water pressure, regardless of drawing.

In the present invention, the surface of the mandrel made of poly-4-methylpentene 1 is crosslinked by irradiation. Crosslinking of the surface is achieved by irradiating an ordinary poly-4-methylpentene-1 mandrel with electron beams or ultraviolet rays. Methylpentene-1 to 10
Either 0.1 to 15 parts by weight of the composition is used to form a mandrel and then irradiated, or the surface of the poly-4-methylpentene-1 mandrel is coated with the functionalized layer. This is achieved by applying, preferably diffusing and then irradiating. Needless to say, the greater the degree of crosslinking by irradiation or the greater the crosslinked thickness, the better the trauma resistance. However, by crosslinking only the surface, the trauma resistance can be greatly improved.

Examples of functional molecules include those having at least two ethylenically unsaturated functional groups, such as trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, Lauryl methacrylate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, triallyl trimellitate, triallyl phosphate, diallylutaconate, triallylaconitate, diallyl fumarate, diallyl citraconate, tetraallyl orthosilicate Ester, tetraallyloxyethane, N,N'-meta-phenylene bismaleimide, phenylmaleimide, triacrylhexahydrotriazine cyanurate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, 1,6-hexanediol diacrylate, ethylene glycol diacrylate,
divinylbenzene, trivinylbenzene, L2-polybutadiene (molecule 1:1000-5000), etc.
Among these, preferred are trimethylolpropane trimethacrylate, triallyl isocyanurate, triallyl trimellitate, and the like.

When a functional monomer is blended with poly-4-methylpentene-1, the blending amount is 0.1 to 15 parts by weight per 100 parts by weight of poly-4-methylpentene-1.
Approximately 0 to 3.0 is appropriate.

The method for blending the functional monomer into poly-4-methylpentene-1 is to heat the poly-4-methylpentene-1 particles and the functional monomer to the highest possible temperature below the melting point of poly-4-methylpentene-1. A method may be used in which the functional monomer is permeated by natural diffusion while being held and stirred or in a stationary state by utilizing the concentration difference of the functional monomer in the poly-4-methylpentene-1 particles. Japanese Patent Publication No. 52-21009 discloses that poly-4-methylpentene-1 and a plasticizer are mixed with a high-speed stirrer, and the plasticizer is forcibly diffused into poly-4-methylpentene-1 particles. Although a method of infiltration is shown, a functional monomer may also be added and diffused/infiltrated together with a plasticizer.

The appropriate amount of electron beam irradiation is about 2 to 20 Mrad, and the appropriate amount of ultraviolet ray irradiation is about 100 to 5000 MJ/am''.

The present invention will be explained in more detail below using Examples and Comparative Examples.

Comparative Example 1 100 parts by weight of poly-4-methylpentene 1 (trade name: TPX MX-004) manufactured by Mitsui Petrochemicals was added with α-olefin oligomer (Rivolup 70 manufactured by Lion Oil & Fats).
) was extruded into an outer diameter of 10 m.
m mandrels were manufactured.

Example 1 10% by weight of triallylisocyanurate in xylene was uniformly applied to the surface of the mandrel obtained in Comparative Example 1. Apply the liquid,
Next, electron beam accelerator DP-1000 (manufactured by Mitsubishi Electric)
The entire surface of the mandrel was irradiated with IMeV and 25 mA (irradiation fft: 5 Mrad) to crosslink the surface.

Example 2 100 parts by weight of poly-4-methylpentene 1 (trade name: TPX MX-001) manufactured by Mitsui Petrochemicals was added with α-olefin oligomer (Rivolup 70 manufactured by Lion Oil & Fats Co., Ltd.)
) and 2 parts by weight of trimethylolpropane trimellitate were extruded to obtain an outer diameter IQ.
A mandrel of mm was manufactured. Then, using the same electron beam accelerator as in Example 1, the entire surface of the mandrel was irradiated under IMeV and 25 mA conditions (irradiation dose: 5 Mrad) to crosslink the surface.

Example 3 A mandrel that differed from Example 2 only in that the amount of trimethylolpropane trimellitate added was 5 parts by weight was used, and it was irradiated (5 Mr.
ad) L, surface crosslinked.

Example 4 The surface of the unirradiated mandrel with an outer diameter of 10 mm obtained in Example 2 was crosslinked in the same manner as in Example 2, except that the irradiation dose was 10 Mr ad.

The mechanical properties of the mandrels obtained in Comparative Example 1 and Examples 1 to 3 were investigated using the method described below, and the results shown in Table 1 were obtained.

Table 1 In the above investigation, the cuff through was measured according to the method of UL Subject 758, and the elongation and yield point strength were measured from the surface of each mandrel with a 1 mm thick JI
No. S3 dumbbells were added and measurements were made using these dumbbells as objects.

As is clear from Table 1, compared to the mandrel of Comparative Example 1, the mandrels of each Example have decreased elongation and increased cut-through and yield strength, which indicates that the surface of the mandrel is hardened. It can be seen that the trauma resistance is improved.

Patent applicant: Mitsubishi Cable Industries, Ltd.

Claims (1)

[Claims] 1. A method for manufacturing a hose manufacturing mandrel, which comprises subjecting a hose manufacturing mandrel made of poly-4-methylpentene-1 to irradiation treatment to crosslink its surface.