DK143788B - PROCEDURE FOR THE MANUFACTURING OF STUFF WOODS WITH RIG WAY BY THERMO-CURE OF PREVENTED PIPES WITH ROOM TEMPERATURE - Google Patents

Description

143788 i

The present invention relates to a process for the manufacture of rigid wall plastic tubes, in which a tube with room-yieldable wall at first is produced, in which optionally fiber reinforcement is embedded, after which the tubes thus produced are flattened and returned to tubular form at the time of use. the tube wall is made rigid by thermosetting.

Tubular articles are usually made either of a slightly bendable and deformable material, such as rubber or flexible thermoplastic resins, so that they are easy to handle when used, and easy to store in a compact state, e.g. small diameter hoses, or also of a rigid, self-supporting material, such as metal, concrete or rigid polymeric resins, so that they can withstand collapse due to self-weight and external influences. Examples include drainage pipes and other water pipes, sewer pipes, air ducts and large liquid tanks.

Large diameter rigid pipes for use as sewer pipes, drain pipes and water pipes are generally manufactured at the factory and transported from here by a truck to the place of application or installation. A very large part of the cost of manufacturing, installing and operating such rigid pipes is the great expense of storing and transporting the pipes from production to installation site, primarily due to the large volume of pipes. Due to their mechanical and physical deficiencies, pipes with flexible or moldable walls have not been able to be used in place of the said large diameter pipes.

From U.S. Pat. No. 3,329,173, it is known to manufacture rigid-walled tubes by first producing a hose that is soft and deformable at room temperature and can therefore be flattened, and later, after being flattened to its place of use and laid out there, can first be substantially traced back to the shape it had at the time of its manufacture, and then subjected to a heat treatment which renders its wall rigid. The tubing known from the United States patent is constructed of a liquid-tight resin film liner wrapped with longitudinally extending filaments impregnated with and / or stored in a curable resin such as an epoxy resin or a polyester resin. The filaments are wound so that the helical lines in a winding layer cross the helices in the following winding layer. Furthermore, longitudinal reinforcement filaments may be stored between two of these wrapping layers. Finally, without these wrapping layers, there is a wrapper with a plastic strip.

Such a manufactured hose can be flattened and transported in the wound state to the place of application where it is first laid out and then by introducing a pressure medium and simultaneous or subsequent heating is converted into a rigid-walled tube, the resin with which the filaments are coated or stored. , cured by heating.

It is an object of the present invention to provide a process whereby, in a much simpler manner, a product is obtained which, in the same way as the known hose, after its initial formation, can be flattened and then converted into a stiff-walled pipe. This is achieved when, according to the invention, the tube with the resilient wall is made of a rigid thermoplastic resin containing thermosetting plasticizer having a curing temperature above the tube manufacturing temperature and optionally a thermosetting initiator.

The material from which the tube is formed is a resin mixture containing a thermoplastic polymer resin, especially a polyvinyl chloride, and a plasticizer which can be cured by heat treatment so that the resin used becomes completely rigid.

Optionally, the tube may be fiber reinforced either with loose fibers or with fibrous fabrics which may be knitted, woven or nonwoven, such as mats or felted material. The reinforcing fibers may be natural, e.g. cotton, or synthetic, e.g. polyamide, polyacrylonitrile, polyester or polyolefin. In addition to the base material, the resin composition may contain other additives such as stabilizers, inhibitors and initiators.

Other thermoplastic polymer resins may be used in place of all or part of the polyvinyl chloride, such as acrylonitrile-butadiene-styrene resin, acrylic resins, polyamides, polyolefins and fluorinated polyolefins. Among the thermosetting softeners which can be used are those consisting of urea resin, melamine resin, epoxy resin, silicone resin, allylic esters, acrylic esters and unsaturated polyesters, all of which can be prepared in known manner either as monomer, dimer, polymer or mixtures thereof. The resin mixture preferably contains a thermosetting reaction initiator such as an organic peroxide, e.g. benzoyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide and tert-butyl perbenzoate. The mixture may also contain a curing inhibitor or a reaction modifier, e.g. hydroquinone.

In addition, the resin mixture may contain a stabilizer and other additives.

The pipe from the first step, ie. the soft, flexible and malleable product can be manufactured in any suitable way, such as by extrusion, molding, welding. The amount of plasticizer used, as well as other amounts of additives, is such that the first product at room temperature, i. 20 ° C, has a flexibility that allows collapsing, folding and recovery thereof as well as a subsequent return to tubular form, even after long storage of the first product. The component parts and composition of the resin blend depend partly on the individual compounds used and partly on the product dimensions and can be easily and quickly determined or determined by one of ordinary skill in the art.

The soft tube is to be prepared at a temperature which does not induce the curing of the thermosetting plasticizer, preferably below 180 ° C and especially preferably below 175 ° C.

The fabricated soft tube is collapsed to a flat shape and as such is transported to the installation or application site. At the installation site, the tubular form, preferably due to its own elasticity, is restored to the desired tubular shape and formed as otherwise desired and heated to the plasticizer's curing temperature, ie. above 180 ° C, preferably to 190-200 ° C, to obtain the desired stiffness.

The shore D hardness (ANSI / ASTM D412-75 and ASTM D638) of the first product is preferably not more than 50, especially between 35 and 45, while the shore D hardness of the cured final product is preferably above 60 and especially between 75 and 85. The army stage should preferably increase the shore D hardness of the product by at least 10, especially by between 30 and 50.

The following examples indicate thermoplastic resins which can be used for the pipe wall. The parts listed are by weight.

Example 1

Parts (a) (b) (c)

Workable polyvinyl chloride resin mixture 100 100 100

Thermosetting plasticizer of the aryl ester type (diarylphthaiate) 20 40 50

Diisooctylphthalate 80 20 10

Stabilizer (Cd.Ba stearate) 135

Thermosetting initiator (di-t-butyl perbenzoate) 123

Shore D hardness before curing 30 40 50

Shore D hardness after curing 35 70 85 The values for the first stage hardness are those found before curing the thermosetting plasticizer upon heating and the hardness after treatment is after heat curing the thermosetting plasticizer.

143788 5

Example 2

Parts (a) (b)

Workable polyvinyl chloride resin mixture 100 100

Thermosetting plasticizer of acrylic ester (tetraethylene) - glycol dimethacrylate 20 40

Diisooctylphthalate 60 20

Stabilizer (Cd.Ba stearate) 3 3

Thermosetting initiator (di-t-butyl perbenzoate) 1 2

Shore D hardness before curing 30 45

Shore D hardness after curing 40 80

Tensile strength (kg / mm) 2.4 4.0

It is noted that the use of the thermosetting initiator causes an increase in tensile strength.

Example 3

Parts (a) (b) (c)

Workable polyvinyl chloride resin mixture 100 100 100

Diisooctylphthalate 80 40 20

Non-saturated polyester thermosetting plasticiser a) Butanediol fumarate 20 b) Dipropylene glycol butyl fumarate 40 c) Dipropylene glycol polysohexyl fumarate 30

Thermosetting initiator (di-t-butyl perbenzoate) 1 23

Shore D hardness before curing 35 45 55

Shore D hardness after curing 40 85 90

Example 4

Workable polyvinyl chloride resin mixture 100

Diisooctylphthalate 60

Bisphenol A type epoxy resin 50

Thermosetting plasticizer of epoxy type (vinylcyclohexan dioxide) 20