JPH02195090A - Production of fireproof synthetic resin pipe and its joint - Google Patents

Abstract

PURPOSE:To prevent a coated layer from being cracked by applying a peeling liquid body on the outer surface of a synthetic resin pipe and fitting set in a metal mold, in producing a fireproof synthetic resin pipe and fitting the outer surface of which is covered withhydraulic inorganic material. CONSTITUTION:The production of a fireproof synthetic resin pipe and its joint, the outer surface of which is covered with hydraulic inorganic material, is as follows: A space is formed on the internal surface of a metal mold of pipe or joint shape and the pipe and joint are set in the mold. A hydraulic inorganic material not hardened and composed of cement, silica sand, light-weight aggregate, organic fiber, etc. is pressed into the space to cover the outer surfaces of the pipe and fitting. Before covering the pipe and fitting, the outer surfaces of them are coated with a peeling liquid body. The type of the liquid body is water, colloidal solution of water and surface active agent, meneral oil, animal oil, vegetable oil, etc. Thus, expansion pressure on the synthetic resin pipe and fitting can be relieved and the coating of hydraulic inorganic material can be prevented from being cracked.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to synthetic resin pipes whose outer peripheral surfaces are coated with nonflammable inorganic materials and their joints, and which are mainly used for indoor distribution of buildings or apartment complexes. The present invention relates to an improved manufacturing method for fire-resistant synthetic resin pipes and joints that are used for water pipes and are effective in preventing the spread of fire to other floors through spaces for water supply and drainage pipes in the event of a fire.

[Conventional technology] In the past, iron pipes were mainly used for water supply and drainage in buildings, but in recent years, pipes made mainly of vinyl chloride have been used because they are susceptible to corrosion and leak easily (and are heavy and cumbersome to install). Pipes made of synthetic resin have come to be mainly used.

However, synthetic resin lacks heat resistance, and in the event of a fire, even if fire doors are in place, the fire will inevitably spread to other floors through the piping space, so the water supply and drainage pipes themselves are made incombustible. There is.

[Problem to be Solved by the Invention 1 This nonflammability is achieved by coating the outer peripheral surface of the synthetic resin pipe or joint with a hydraulic inorganic material and curing it. hardening due to instantaneous or long-term pressure from inside due to differences in internal and external expansion and contraction, such as expansion of synthetic resin pipes due to the passage of hot water, etc. during piping, hydraulic properties during curing, and contraction of inorganic materials. It is known that stress-induced cracking of hydraulic inorganic materials during or after curing occurs frequently.

As a countermeasure for this, there is a method of covering part or all of the outer peripheral surface of a synthetic resin pipe, etc. with a layered material such as foamed polystyrene, setting it in a mold, and then press-fitting mortar into the gap to cover it (specially No. 112813/1983) and the like have been proposed.

However, the former method has problems in that the step of covering with expanded polystyrene is costly and the productivity is low.

[Means for Solving the Problems J] The present invention provides a method for manufacturing a fire-resistant synthetic resin pipe or a joint whose outer peripheral surface is coated with a hydraulic dihydric inorganic material. When filling the gap formed by the inner peripheral surface of the mold with an uncured hydraulic inorganic material, apply a releasable liquid to the outer peripheral surface of the synthetic resin pipe or joint in advance. This manufacturing method is characterized by the following.

That is, by applying a releasable liquid to the outer circumferential surface of a synthetic resin pipe or joint to be coated with a hydraulic inorganic material before filling it into a mold, adhesion between the synthetic resin surface and the hydraulic inorganic material can be prevented. By reducing the adhesive properties, a void is created between the adhesive surfaces.

In this case, the inner surface of the mold must be coated with a mold release agent to avoid adhesion with the hydraulic inorganic material, but the adhesion of the contact surface and the adhesion between the synthetic resin surface and the hydraulic inorganic material Due to the nature of the mold, there is a small gap (approximately 0.8 mm or less) between the synthetic resin and the hydraulic inorganic material in all or part of the surface during demolding.
is formed. This gap is extremely effective in preventing cracks caused by stress in the hydraulic inorganic material during or after curing.

In the present invention, synthetic resin pipes or joints are mainly made of vinyl chloride, but are not limited thereto, and thermoplastic resins such as polyethylene and polypropylene can generally be used. However, as can be seen from the content of Kanmei, thermosetting resins are equally effective.

In addition, hydraulic (fire-resistant) inorganic materials are compositions containing cement, silica sand, lightweight aggregate, organic or inorganic reinforcing fibers, etc. Portland cement is usually used as the cement, and in some cases Alumina cement and white cement are used.

This cement composition is mixed with as little water as possible to form a cement mortar, which is then press-fitted into a mold using an extruder or the like.

Water, water,
It is a colloidal solution of water and a surfactant, mineral oil, animal or vegetable oil, or a suitable mixture of these, and a suitable mixture of petroleum, organic solvent, etc. in consideration of coatability and workability. It is not necessary to apply the releasable liquid to the entire outer circumferential surface of the synthetic resin pipe joint, and it is sufficient to apply the releasable liquid only to the outer circumferential surface of the opening, which is relatively problematic.

[Function] As can be seen from the above explanation, if a releasable liquid is applied to the surface to be coated with a synthetic resin and a mortar of hydraulic inorganic material is press-fitted, the adhesive force on this contact surface will be:
It is thought that the mortar is extremely fluid compared to the case where no releasable liquid is applied, and therefore adhesion is inhibited, resulting in the formation of gaps at this interface.

As a result, it is thought that the pressure of expansion of the synthetic resin due to heating (by passing hot water, etc.) during or after curing of the hydraulic inorganic material is alleviated, thereby preventing cracks in the cured inorganic material coating. .

[Example] Specific examples of the present invention are shown below.

(Example 1) A vinyl chloride pipe fitting DL 75 coated with a release liquid (hereinafter referred to as a release agent) on its entire outer circumferential surface was set in a half-split metal mold coated with a release agent, and The gap formed between the outer peripheral surface of the pipe joint and the inner peripheral surface of the metal mold is filled with a ring-shaped uncured hydraulic inorganic material. After filling, the vinyl chloride pipe fitting coated with uncured hydraulic inorganic material is removed from the mold. During demolding, a gap of about 0.6 mm or less is partially formed between the vinyl chloride pipe joint and the covering material, which is the object of the present invention. After demolding, the temperature is approximately 60℃ and the cleanliness level is 95R8% to facilitate handling and increase productivity.
Steam heating curing is performed for 5 hours. The gaps formed during heat curing were confirmed as they were. The stripping agent is a mixture of organic fatty acids, vegetable oils, surfactants, chlorinated solvents, and petroleum solvents.

The coating method is as simple as applying a thin layer to the entire outer circumferential surface of the PVC pipe joint using a sponge.The composition of the hydraulic inorganic material used for filling is 45 wt% of ordinary Portland cement, 15 wt% of silica sand, and 7 wt% of lightweight aggregate. organic fiber 2wt
%, others 0.7 wt%, and water 20.3 wt%.

(Example 2) Instead of applying a release agent to the entire outer peripheral surface of the vinyl chloride pipe joint in Example 1, the release agent is applied only to the opening of the receiver. The experiment is otherwise conducted under exactly the same conditions as in Example 1.

As a result, a gap of about 0.6 mm was formed around the semicircumference of the mouth of the receiver.

(Example 3) A solution prepared by mixing tall oil fatty acid, soybean oil ester, nonionic surfactant, and kerosene in water as a release agent was applied only to the mouth of the tube. All other conditions were the same as in Example 1.

As a result, the receiver is approximately 0.6 mm across the same semicircle on the outer circumferential surface of the mouth.
A gap on the order of mm or less was formed.

(Reference example) Use two fire-resistant synthetic resin pipe fittings molded in Examples 1, 2 and 3 above, connect a straight pipe to each opening, and
Piping was done in a shape. The length of the straight pipe at the open end was 300 mm, and the length of the straight pipe between the joints was 500 mm.

Hot water at 80° C. was passed through this U-shaped tube and the coating of the fire-resistant synthetic resin pipe joint was inspected after 15 minutes, but no cracks were observed in any of the hydraulic inorganic material coatings.

On the other hand, for comparison, fire-resistant synthetic resin pipe fittings were made without applying a release agent and piped in the same U-shape.
Although all other conditions were the same, cracks were observed in all or part of the coating material of each joint.

[Effect of the Invention J] A gap for stress relaxation could be reliably formed between the outer circumferential surface of a synthetic resin pipe or joint and the surface of the hydraulic amorphous material by the extremely simple method of applying a release agent.

Claims (1)

[Claims] In a method for manufacturing a fire-resistant synthetic resin pipe or fitting whose outer peripheral surface is coated with a hydraulic inorganic material, uncured When press-fitting hydraulic inorganic materials,
A manufacturing method characterized in that a releasable liquid material is applied in advance to the outer peripheral surface of the synthetic resin pipe or joint.