JPS5838393B2 - Manufacturing method of resin lined concrete pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an improved method for manufacturing hollow cylindrical, i.e. pipe-shaped, concrete products having excellent acid resistance, salt resistance and abrasion resistance, the inner surface of which is lined with an unsaturated polyester resin composition. It is related to.

Pipe-shaped concrete products, such as typical Hume pipes, are currently used in large quantities as water and sewer pipes, drainage pipes, agricultural water pipes, and the like.

However, since the material $1 is made of concrete, it has the disadvantage that it is easily corroded by inorganic acids, organic acids, inorganic salts, oils and fats, etc.

Conventionally, in order to improve the acid resistance and salt resistance of this concrete IJ-container pipe, there has been a method of lining the concrete pipe after the concrete has been cured with a compound made of, for example, an epoxy resin mixed with a filler.

However, this method has the disadvantage that peeling is likely to occur due to shrinkage when the epoxy resin hardens.
In addition, once a pipe-shaped concrete product is formed and cured to harden the concrete, the inner surface of the concrete product is lined with epoxy resin or the like using centrifugal force, so it is difficult to hold the mold until the product is completed. The disadvantages are that the occupancy time is very long and, furthermore, the cost of the finished acid-, salt- and abrasion-resistant internally lined pipe-like concrete product is high because the epoxy resin is quite expensive.

We are conducting extensive research and development with the aim of establishing a simple, low-cost, and highly practical manufacturing method for pipe-shaped concrete products that have an inner lining layer with good adhesion and excellent acid resistance, salt resistance, and abrasion resistance. As a result of our progress, we found that by using a low-shrinkage unsaturated polyester resin as the liquid resin for lining, and by using a resin composition in which this resin was mixed with flaky fillers such as mica flakes and glass flakes, we were able to line the inner surface for the first time. As a manufacturing method for resin-lined pipe-shaped concrete products, a highly streamlined manufacturing method involves immediately lining the concrete hollow pipe with the resin composition and curing the concrete layer and the resin lining layer at the same time. We were able to develop a method.

One feature of the method of the present invention is that when forming a concrete layer with inner lining, floating water generated on the inner surface is simply drained, and immediately thereafter, the liquid resin composition is transferred by centrifugal force. In this case, if a known resin such as an epoxy resin or an unsaturated polyester resin, which is usually used as a liquid resin, is used, there will be a gap between the uncured concrete IJ layer and the resin layer. Since adhesive strength is not developed, a serious problem arises in that significant delamination occurs between the concrete layer and the resin layer due to curing shrinkage of the resin.

Therefore, it has been found that the problem of delamination due to curing shrinkage of the resin can be solved by using an unsaturated polyester resin with low shrinkage.

However, in order to cure the concrete layer and harden the resin layer, it is necessary to perform heat curing such as steam curing, but in the process of cooling the molded product after this heat curing, ordinary particulate filler is added. When a mixed low-shrinkage unsaturated polyester resin composition is used as a lining, a problem has been found in that the lining layer, which was in close contact with each other before cooling, causes delamination when cooled.

This is because when particulate fillers are used, the coefficient of thermal expansion of the lining layer is approximately 4 to 5 times that of the hardened concrete, within the range of moldable resin usage, and the lining layer is It became clear that this was caused by the shrinkage of the concrete layer being greater than that of the concrete layer.

As a result of intensive study on a method to prevent delamination during cooling due to the difference in thermal expansion coefficient, we decided to use a liquid resin composition consisting of a low-shrinkage unsaturated polyester resin mixed with a flaky filler as a coating resin composition. By using it as a concrete layer, it is possible to completely prevent delamination due to curing shrinkage of the resin, as well as delamination due to the difference in thermal contraction between the concrete layer and the lining layer, which occurs during cooling after heat curing such as steam curing. For the first time, we discovered that it is possible to perform the molding of the concrete layer and the resin lining in a continuous manner, so to speak, to integrally mold a resin-lined pipe-shaped concrete product.

To explain the present invention in more detail, in the method of integrally molding a resin-lined pipe-shaped concrete product according to the present invention, removing floating water on the surface generated during centrifugal molding of the concrete layer is a method for removing suspended water from the surface of the lining layer or the water generated during molding. Necessary to prevent breakage and pinhole formation.

To this end, it is necessary that floating water on the surface of the molded concrete be drained before lining with resin.

Drainage is done by tilting the concrete molding.
It is enough to remove the water that was floating on the inside of the precept.

After draining, the surface of the concrete layer can be further dried by continuing the rotation.

As mentioned above, when lining and curing a resin composition on an uncured concrete layer, the concrete layer itself has almost no strength, and the adhesive force between the concrete layer and the resin layer is extremely weak. For,
Even slight curing shrinkage of the resin causes delamination.

Therefore, it is necessary to use a liquid resin that exhibits almost no curing shrinkage.

Examples of such resins include low-shrinkage, room-temperature-curing unsaturated polyester resin BW of the type in which a thermoplastic resin is added to unsaturated polyester resin, such as saturated polyester and its modified products, polyvinyl acetate, cellulose acetate butyrate, etc. A so-called one-component low-shrinkage unsaturated polyester resin in which a plastic resin is added to an unsaturated polyester resin, or (a) an unsaturated polyester, (b) a heptanomer copolymerizable with (a), and (C) styrene. system copolymer, (
d) An unsaturated polyester resin composition consisting of a comb-shaped copolymer having a styrene copolymer as a trunk and saturated polyester segments as branches is used.

Among these, the unsaturated polyester resin composition consisting of (a), (b), and (c) and (a) is particularly excellent in low shrinkage, and is almost non-shrinkable or can be expanded during curing. Furthermore, since it has a low viscosity, it has excellent workability compared to the case of resin lining that uses centrifugal force, and is preferable in the production of the resin-lined pipe-shaped concrete product of the present invention.

As the unsaturated polyester (a) constituting the unsaturated polyester resin composition, as the unsaturated dibasic acid raw material,
For example, maleic anhydride, fumaric acid, itaconic acid, polyhydric alcohol raw materials such as propylene glycol, ethylene glycol, diethylene glycol, dipropylene glycol, phthanediol, glycerin, duntaerythritol, triethylene glycol, pentanediono hexanediol , neopentyl glycol,
Hydrogenated bisphenol A1 Bisphenol A alkylene oxide adduct, propylene oxide, ethylene oxide, etc., and polybasic acid raw materials such as phthalic acid, isophthalic acid, terephthalic acid, endomethylenetetrahydrophthalic acid, tetrahydrophthalic acid, tetrachlorphthalic acid, tetrahydrophthalic acid, etc. It is a known unsaturated polyester produced by polycondensation using a known method using bromphthalic acid, het acid, hexahydrophthalic acid, succinic acid, adipic acid, trimellitic acid, and their acid anhydrides.

In addition, (b) Waa) Examples of the heptanomer copolymerizable with the unsaturated polyester include alkenyl aromatic heptanomers such as styrene, α-methylstyrene, and tert-butylstyrene, and alkyl esters of acrylic acid and methacrylic acid. , vinyl acetate, etc. are used, but styrene is particularly preferred.

Examples of the styrene polymer (C) added for the purpose of imparting low shrinkage to the above unsaturated polyester resin include polystyrene, high-impact polystyrene, styrene-butadiene-styrene block copolymer, and styrene. Styrene-acrylic nitrile copolymer, styrene-methyl methacrylate copolymer, acrylonitrile-styrene mixed graft polybutadiene resin, etc. are used.

The content of the styrene polymer in the composition is -0 relative to the total amount of the unsaturated polyester and the heptanomer copolymerizable therewith in order to obtain a sufficient low shrinkage (no shrinkage) effect.
．． 5 times or more, preferably ±100
10 times or more by weight, and 10 times or less based on the total amount of unsaturated polyester and 3 monomers copolymerizable therewith in order to obtain good handling properties of the lining composition and excellent adhesive strength with the base material. It is preferable to use a weight of

(c) A comb-shaped copolymer having a styrene polymer chain as a trunk and a saturated polyester segment as branches, which is used for the purpose of improving the dispersion stability of a styrenic polymer (d), is used for the purpose of improving the dispersion stability of a styrene polymer. A method in which a saturated polyester having an unsaturated double bond is copolymerized with an aromatic vinyl heptanomer, a method in which a copolymer of maleic anhydride and an aromatic vinyl monomer is reacted with a saturated polyester having a hydroxyl group at one end, or an epoxy It can be produced by a method in which a copolymer of a vinyl monomer having a group and an aromatic vinyl monomer is reacted with a saturated polyester having a carboxyl group at one end.

Such a comb-shaped copolymer may cause styrene polymers to be deposited on the surface and interface with the substrate during the separation and curing of the styrenic polymer during storage and centrifugation of the lining composition used in the method of the present invention. This suppresses the extrusion of the coalescence, resulting in a reduction in the low shrinkage effect, deterioration of the surface condition, decrease in adhesive strength, or peeling of the base material and lining layer caused by the extrusion of the styrene polymer. It is an important component that has a suppressing function.

The amount of such a comb-shaped copolymer used as a dispersion stabilizer is effective within the range of 0.0 to 2 times the weight of the styrenic polymer in the composition, preferably 0.
．． It is 1.0 times the weight from 03 times the weight.

In the present invention, the concrete layer and the resin lining layer are cured simultaneously by heat curing, but in that case, even if the lining is made of a composition using a low-shrinkage unsaturated polyester resin, the following conditions must be met. If this is not satisfied, delamination will eventually occur.

The condition is that the coefficients of thermal expansion in the circumferential direction of both the concrete layer and the resin lining layer are almost the same during cooling after heating and hardening.

Indeed, it is possible to reduce the coefficient of thermal expansion of a cured resin by adding a particulate filler to a low-shrinkage unsaturated polyester resin.If only a particulate filler was used, the resin composition would When lined on the inner surface of a concrete layer by centrifugal force, it inevitably reduces the thermal expansion coefficient of the lining layer to the thermal expansion coefficient of the concrete layer, provided that it flows easily and forms a uniform layer. It is impossible to do so, and as a result, delamination that occurs during cooling after heat curing cannot be prevented.

However, by replacing all or part of the filler with a flaky filler such as mica flakes or glass flakes,
By orienting these in the circumferential direction by the flow caused by centrifugal force during lining, the combined effect of the flaky filler allows lining to be performed within a range of resin amount that does not significantly impair the fluidity of the resin composition during lining. The coefficient of thermal expansion of the layer can be significantly reduced to match that of the concrete IJ layer.

This makes it possible to completely prevent delamination that occurs during cooling after heat curing.

The flaky filler that can be used in the present invention includes:
Examples include glass flakes and mica flakes.

The glass flakes used have a diameter of 500 mesh to 1 c^, preferably 100 mesh to 0.5 c, and a thickness of 0.1 to 40 microns, preferably 0.2 to 30 microns.

The mixing ratio of glass flakes is 5 to 80 parts by weight, preferably 10 to 50 parts by weight, based on 10 parts by weight of resin.

Mica flakes have a greater effect of lowering the coefficient of thermal expansion of the lining layer to F than glass flakes, and are the most preferred flake filler.

The mica flakes that can be used in the present invention are the usual mica calyces such as muscovite, phlogovite (suzolite), biotite, lepidolite, margarite, sericite, chlorophyllite, but especially phlogovite (suzolite). For example, Suzolite) is preferred because it has excellent bonding properties with resin.

In the present invention, the weight average aspect ratio of mica flakes is determined by the following formula.

Weight average aspect ratio = flake diameter (mD)/flake thickness (1) 1 ml per stone + D2 m+...
・・+Dnmn / t1ml +t2m2 +−・−
...*+ tnmn where D1 is the average diameter of one mica flake, t1 is the average thickness of the flake, m is D1, t
The total weight of a group of flakes having a shape of 1 is shown.

D2, t2, m2, Dn, tn, and mn have the same meaning.

Further, the average flake diameter of each of D1, D2, . . . Dn is determined by the area of π(Iy!)2=1 flake.

In order to improve the bonding state between the mica flakes and the resin, and to layer the mica flakes in parallel in the resin by centrifugal force, to obtain a lining layer with a low coefficient of thermal expansion and excellent resistance to penetration of chemical solutions, mica was added. The weight average aspect ratio of the flakes is required to be at least 30.

In the present invention, the aspect ratio of the mica flakes is preferably as large as possible, and those having an aspect ratio of 60 or more, particularly 90 or more are most preferably used.

In general, mica flakes are straight D) 500 mesh ~
Preferably 100 mesh to 0.5 ctn% thickness (
t)0. 1-40 microns preferably 0.2-30
It is preferable to appropriately select from among microns depending on the desired weight average aspect ratio.

When lining a mixture of flaky filler and low-shrinkage unsaturated polyester resin, the construction conditions (mixing amount of flake filler and The rotation speed of the mold during lining construction is selected.

The rotational speed of the mold during lining construction is preferably as high as possible in order to orient the flaky filler parallel to the substrate, but it is faster than the rotational speed of the mold during formation of the concrete IJ layer. This is undesirable because water may separate from the concrete layer to the surface and destroy the lining layer.

The appropriate thickness of the lining layer is 0.2 to 10y+m+, preferably 0.5 to 6m+.

The resin-lined pipe-shaped concrete product obtained by the method of the present invention has significantly improved cracking and peeling caused by repeated temperature changes, and has excellent acid resistance, salt resistance, and abrasion resistance. This greatly expands the use of fume tubes as sex tubes and pneumatic waste transport tubes.

Next, the present invention will be specifically explained with reference to Examples.

Parts in the examples are parts by weight unless otherwise specified.

Reference Example 1 (1) Preparation of unsaturated polyester resin 2.0 mol of maleic anhydride, 4.0 mol of phthalic anhydride,
5.4 moles of fluoropylene glycol and 0.9 moles of diethylene glycol were heated in a reaction vessel to 200° C. while passing a nitrogen gas stream in a conventional manner to carry out an esterification reaction to obtain an unsaturated polyester having an acid value of 45.

45 parts of this unsaturated polyester was dissolved in 55 parts of styrene monomer, and hydroquinone o. oii part was mixed to obtain an unsaturated polyester resin.

(2) Preparation of styrene monomer solution of polystyrene Add 70 parts of styrene monomer to polystyrene (Asahi Dow Industrial Co., Ltd.,
A polystyrene solution was obtained by dissolving 30 parts of Styron 666).

(3) Preparation of dispersion stabilizer 1 mole of phthalic anhydride, 1 mole of succinic anhydride, and 2.1 moles of ethylene glycol were heated to 150°C under a nitrogen gas stream in a reaction vessel using a conventional method, and reacted for 2 hours to half It was made into an ester.

Thereafter, the mixture was heated to 200° C. to proceed with the esterification reaction to obtain a saturated polyester having a hydroxyl value of 17.

The saturated polyester was cooled to 160°C and 0.07 mol of maleic anhydride was added.

Then, add 1 mouth of dibutynorephthalate to 1 mouth of polyester.
00 parts, stirred well to dissolve, cooled to 80°C, and then added 50 parts of styrene monomer to form a uniform solution.

Further, 1 part of benzoyl peroxide was added to carry out a radical copolymerization reaction at 80°C, and the polymerization was completed in 4 hours.

A comb-shaped copolymer with polystyrene as the trunk and saturated polyester as branches was obtained.

(4) Preparation of resin composition for lining Add 70 parts of the unsaturated polyester resin prepared in 1) to (
After 2.5 parts of the dispersion stabilizer (3) was mixed, 30 parts of the polystyrene solution (2) was added and dispersed with stirring.

After mixing 30 parts of susolite mica (weight average aspect ratio 60, particle size 40-70 mesh) with 100 parts of this resin liquid, 0.5 part of cobalt naphthenate (cobalt content: 6%) solution and 55 parts of methyl ethyl ketone peroxide
A lining composition was prepared by sequentially adding 1.0 part of the multi-solution.

Example 1 Concrete with a unit cement amount of 420 A7 and a water-cement ratio of 40 is rotated at a low speed with a diameter of 200 m and a length of 500 W.
The sample was placed in a centrifugal mold (No. 1), the rotation speed was further increased, and the rotation was continued for 15 minutes in a state where a centrifugal force of 30 G was generated.

Then, the rotation was stopped and the mold was tilted to completely drain the floating water.

Thereafter, 2.4 of the resin composition prepared in Reference Example 1 was immediately added.
k. Resin lining was performed at a mold rotation speed such that the centrifugal force was IOG, and the rotation was stopped after 20 minutes.

The lining layer is gelled, and no sagging occurs.
There were also no pinholes.

After precuring this molded product for 2 hours at room temperature, 70±5
Steam curing was performed for 3 hours at a temperature of ℃ (/X) to completely harden the concrete layer and lining layer.

After cooling, the mold frame was removed to obtain a molded product. The lining layer showed no delamination at all, and it produced a clear tone when struck with a hammer.

Reference Example 2 (1) Preparation of unsaturated polyester resin 2.0 monooles of maleic anhydride, 4.0 moles of phthalic anhydride, 5.4 moles of phthalic anhydride, 5.4 moles of diethylene glycol, and 0.9 moles of diethylene glycol were mixed with nitrogen in a reaction vessel by a conventional method. An esterification reaction was carried out by heating to 200° C. while passing a gas stream, and an unsaturated polyester with an oxidation level of 45 was obtained.

55 parts of this unsaturated polyester was dissolved in 45 parts of styrene monomer, and 0.011 part of hydroquinone was mixed therein to obtain an unsaturated polyester resin.

(2) Preparation of resin composition for lining 100 parts of the unsaturated polyester resin prepared in 1) was mixed with 30 parts of suzolitic mica (weight average aspect ratio 60, particle size 40-70 mesh), and naphthenic acid A lining resin composition was prepared by sequentially adding 0.5 parts of a cobalt (cobalt content: 6%) solution and 1.0 part of a methyl ethyl ketone peroxide 55 multi-solution.

Comparative Example 2 When a resin-lined concrete pipe was obtained using the resin composition prepared in Reference Example 2 in the same manner as in Example 1, significant delamination occurred between the concrete layer and the lining layer.

Comparative Example 3 125 parts of silica powder (200 mesh pass) was added to 100 parts of the same unsaturated polyester resin liquid as that used in Example 1.
150 parts of river sand were added, and further 0.5 part of cobalt naphthenate (cobalt content: 5%) and 1.0 part of methyl ethyl ketone peroxide were added to obtain a resin composition for lining.

When a resin-lined concrete pipe was obtained using this resin composition in the same manner as in Example 1, significant delamination occurred between the concrete layer and the lining layer.

Claims (1)

[Claims] 1. After pouring cement concrete into a rotating mold and centrifugally forming a hollow tube, excess water floating on the inner surface of the hollow tube is drained and removed, and then low shrinkage After lining the inner surface of a cement concrete hollow tube using centrifugal force with a coating composition containing an unsaturated polyester resin composition and a flaky filler as essential components, heat curing is performed to cure the concrete layer. A method for manufacturing a resin-lined concrete pipe characterized by simultaneously curing the lining layer. 2 As a low shrinkage unsaturated polyester resin composition, (
a) unsaturated polyester, (b) a monomer copolymerizable with (a), (C) a styrene copolymer, and (d) a comb-shaped copolymer having a styrene copolymer as a trunk and saturated polyester segments as branches. 2. A method for producing a resin-lined concrete pipe according to claim 1, which uses an unsaturated polyester resin composition consisting of a composite. 3 As a flaky filler, the weight average aspect ratio is 3
The method for producing a resin-lined concrete pipe according to claim 1, wherein 0 or more mica flakes are used. 4 As a low shrinkage unsaturated polyester resin composition, (
a) unsaturated polyester, (b) monomer copolymerizable with (a), (c) styrene copolymer, (d) comb-shaped copolymer with styrene copolymer as the trunk and saturated polyester segments as branches Claim 1, in which a polyester resin composition consisting of a combination is used, and mica flakes having a weight average aspect ratio of 30 or more are used as the flaky filler.
The method for manufacturing a resin-lined concrete pipe described in .