JPH0140677Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hose with chemical and heat resistance suitable for transporting fluids containing organic solvents.

In the coating industry, various organic solvents are often used in combination in order to impart fluidity to coating film-forming components. The organic solvents used can be broadly divided into polar solvents and nonpolar solvents.
Examples of polar solvents include alcohols such as methanol, ethanol, butanol, isopropyl alcohol, and benzyl alcohol, esters such as methyl acetate and butyl acetate, ketones such as acetone and methyl ethyl ketone, ethylene glycol,
Glycols such as polypylene glycol are often used. Further, as non-polar solvents, mineral spirits, petroleum such as volatile oil and kerosene, and aromatic hydrocarbons such as toluene and xylene are often used.

The paint is diluted with the organic solvents mentioned above and applied to the surface to form a paint film.
In recent years, a hot spray coating method has been developed that reduces the use of solvents by heating the paint to 60 to 70°C to lower its viscosity. Hoses used in such hot spray coating methods are therefore required to have both solvent resistance and heat resistance.

On the other hand, as painting hoses, hoses made of rubber or thermoplastic resins such as polyethylene, soft vinyl chloride, polypropylene, nylon, and urethane are widely used. Rubber or urethane hoses have the advantage of being flexible and easy to work with, but they may dissolve or swell in organic solvents and do not have sufficient chemical resistance. However, it has the serious drawback of not being able to withstand long-term use. On the other hand, hoses made of polyethylene, polypropylene, or nylon have better chemical resistance than those made of rubber, urethane, or soft vinyl chloride, but they are hard and lack flexibility. It has the disadvantage of poor workability. Moreover, in terms of chemical resistance, it has the disadvantage that it cannot withstand long-term use because it dissolves or swells when it comes into contact with organic solvents at temperatures of 60 to 70°C, such as those used in hot spray painting. There is.
Another drawback is that it is impossible to avoid the solvent crack phenomenon in which cracks occur due to the solvent when the hose is bent for use.

The present invention is an attempt to solve the above-mentioned drawbacks of conventional hoses; it does not swell or dissolve even when exposed to high-temperature organic solvents, is highly flexible, and has good workability. It is an object of the present invention to provide a hose that is free from solvate cracks caused by solvents.

That is, the hose according to the present invention is characterized in that the inner layer is formed of silicone-grafted polyolefin, the outer layer is formed of silicone-grafted ethylene-vinyl acetate copolymer, and these are crosslinked to form an integral structure.

The present invention will be explained below with reference to the drawings.

The figure shows a hose according to the present invention, hose 1
is integrally constructed by forming the inner layer 2 of silicone-grafted polyolefin and the outer layer 3 of silicone-grafted ethylene-vinyl acetate copolymer, and crosslinking them.

The silicone-grafted polyolefin constituting the inner layer 2 includes silicone-grafted polyethylene, silicone-grafted polypropylene,
Examples include silicone-grafted ethylene propylene copolymer. By using silicone grafted polyolefin as inner layer 2,
In particular, products with excellent chemical resistance can be obtained.

As the outer layer 3, a silicone-grafted ethylene vinyl acetate copolymer is used. Silicone-grafted ethylene-vinyl acetate copolymer is particularly flexible, so a hose with good workability can be obtained. The content of the ethylene vinyl acetate copolymer in the silicone grafted ethylene vinyl acetate copolymer is determined from 12 to 12 to
Preferably it is 30% by weight.

Methods for producing silicone-grafted polyolefins and silicone-grafted ethylene-vinyl acetate copolymers are widely known. It can be produced by reacting in the presence of a polymerization initiator.

Further, the crosslinking reaction between the silicone-grafted polyolefin, which is an inner layer component, and the silicone-grafted ethylene-vinyl acetate copolymer, which is an outer layer component, can be carried out using a condensation catalyst such as dibutyltin dilaurate.

Next, a method for manufacturing a composite hose according to the present invention will be explained.

A small amount of dibutyltin dilaurate is mixed with silicone-grafted polyolefin, which is the inner layer component, and
In addition, a small amount of dibutyltin dilaurate is mixed with the silicone-grafted ethylene-vinyl acetate copolymer that is the outer layer component, and the inner layer and outer layer components are extruded into a tubular shape from a common mold using a two-layer extrusion molding method. Forms the outer layer. Since the inner layer component and the outer layer component have fusion properties, an uncrosslinked composite hose in which the inner layer and the outer layer are tightly adhered and integrated is obtained. Since each of these uncrosslinked hoses contains dibutyltin dilaurate, a crosslinking reaction proceeds when brought into contact with water. Specifically, this crosslinking reaction is allowed to proceed by immersing the uncrosslinked hose in water. The crosslinking reaction proceeds even if water at room temperature is used, but in order to complete the crosslinking reaction in a short time, hot water at 50 to 60°C may be used.

In the composite hose of the present invention, a hard screw reinforcing core made of synthetic resin or metal wire is embedded in the silicone-grafted ethylene-vinyl acetate copolymer, which is the outer layer component, in order to withstand the deformation of the pipe due to external forces. You may do so. Further, in order to impart pressure resistance to the hose, a reinforcing layer made of synthetic fiber or metal wire may be provided on the hose according to the present invention. Furthermore, if you want to add wear resistance to the hose,
The hose according to the present invention may be coated with a synthetic resin such as vinyl chloride or urethane.

Next, examples will be described.

Example Siogracene V4S7 (trade name, manufactured by Showa Denshin Co., Ltd.), a commercially available silicone-grafted high-density polyethylene resin, was used as the inner layer component, and EVA Siogracene (trade name), a commercially available silicone-grafted ethylene-vinyl acetate copolymer, was used as an inner layer component. (manufactured by Showa Cable and Wire Co., Ltd., vinyl acetate content 15% by weight) as the outer layer component, mixed with 10% by weight of a catalyst masterbatch consisting of dibutyltin dilaurate, and extruded using a two-layer extrusion molding machine, inner diameter 7.0 mm, inner layer thickness 0.3
A hose with an outer layer thickness of 1.2 mm was molded. Then,
This hose was immersed in 60℃ hot water for 24 hours to determine the gel fraction.
A 70% cross-linked composite hose was obtained.

When the thus obtained hose according to the present invention was compared with commercially available polyethylene hoses and nylon hoses, it was found to be excellent in flexibility and satisfactory.

In addition, in order to examine chemical resistance, the hose according to the present invention and a nylon hose were immersed in methyl alcohol, a polar solvent, for 30 days at 20°C.
The weight of the hose according to the present invention increased by only 0.3%, while the weight of the nylon hose increased by 10.5%. From this, it can be seen that the hose according to the present invention has extremely excellent chemical resistance.

Furthermore, in order to investigate the solvent crack resistance, when the hose according to the present invention and a polyethylene hose were bent and immersed in xylene at 60°C, the hose according to the present invention did not show any cracks even after 10 days. On the other hand, the polyethylene hose developed cracks at the bends in a short period of time and completely melted within one day. From this, it can be seen that the hose according to the present invention has excellent high temperature solvent resistance and also excellent solvent crack resistance.

Furthermore, in order to consider heat resistance,
The hose according to the present invention and the polyethylene hose
When heated to a temperature of 100°C, the hose according to the present invention showed no change in appearance, whereas the polyethylene hose was thermally deformed and could not maintain its original shape. This shows that the hose according to the present invention has excellent heat resistance.

As explained above, the hose according to the present invention is
The inner layer is made of silicone-grafted polyolefin, the outer layer is made of silicone-grafted ethylene-vinyl acetate copolymer, and both are crosslinked to form an integral structure. As described above, since the outer layer is formed of a flexible silicone-grafted ethylene-vinyl acetate copolymer having rubber elasticity, it has excellent flexibility and softness, and is easy to handle and workable. It also has the advantage of having a strong transverse rupture strength against repeated bending, and is resistant to breakage even when subjected to impact. Furthermore, since the hose according to the present invention is integrally constructed by cross-linking the inner layer component and the outer layer component, it has improved chemical resistance and heat resistance, and there is no possibility of solvent cracks occurring, so it can be used in a wide range of applications. It can be used under harsh conditions even with chemicals, and its applications are extremely wide-ranging.

[Brief explanation of the drawing]

The figure is a perspective view of a hose according to the present invention. 1...Hose, 2...Inner layer, 3...Outer layer.

Claims (1)

[Scope of utility model registration request] The inner layer is formed of silicone-grafted polyolefin, the outer layer is formed of silicone-grafted ethylene-vinyl acetate copolymer, and the inner layer component, silicone-grafted polyolefin, and the outer layer component, silicone-grafted ethylene-vinyl acetate copolymer, are cross-linked. A composite hose that is constructed in one piece.