JPH03287601A - Molding of pipe - Google Patents

Abstract

PURPOSE:To obtain a pipe improved in chemical resistance, weathering resistance, hardness, optical properties and surface smoothness by adding a specified polymerizable substance and a specified liquid substance to a mold provided in a centrifugal molding machine and polymerizing the polymerizable substance under a centrifugal force. CONSTITUTION:A cylindrical mold 1 purged with an inert gas 5 atmosphere is charged with a polymerizable substance 2 comprising a monomer or oligomer consisting essentially of an aliphatic, alicyclic or aromatic dihydric alcohol di(allyl carbonate) compound of the formula (wherein R is a residue of a dihydric alcohol, and n is 1-10 on the average) and/or its di(meth)acrylic compound and a liquid substance 3 having a low solubility in component 2 and having a specific gravity lower than that of component 2 (e.g. ethylene/alpha-olefin random copolymer of a number-average mol.wt. of 500-5000), and the mold is sealed with flanges 6 or the like and rotated in the direction of the arrow 7 to polymerize component 2 into a pipe.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a pipe forming method in which a cylindrical mold is rotated to apply centrifugal force to a polymerizable substance in the mold, and in particular, to This invention relates to a pipe forming method that prevents polymerization of polymerizable substances from being inhibited by oxygen and that produces pipes with excellent weather resistance, chemical resistance, hardness, optical properties, and surface smoothness.

<Problem to be solved by the invention> The inner surface of an iron pipe, etc. is polished and subjected to surface treatment such as plating to achieve surface precision, then molded (casting mold), a monomer is poured into the mold, and both ends are flanged. There is a known method of centrifugal molding of pipes, in which the mold is rotated and the seven polymers in the mold are polymerized under centrifugal force to form a pipe.

On the other hand, diethylene glycol bisallyl carbonate,
It is known that when a monomer or oligomer such as methyl methacrylate is poured into a cylindrical mold and cast-polymerized into the shape of a pipe or the like, a polymer with excellent weather resistance, chemical resistance, etc. can be obtained.

However, in the pipe forming method in which the material is cast into a cylindrical mold, the volume contracts during polymerization, so polymerization must be carried out while the shape of the mold follows this volumetric contraction.

If a part of the mold must be exposed to the air for polymerization, the radicals necessary for polymerization will be consumed by the oxygen in the air, and the surface in contact with the air will be
There is also the problem that a sufficient degree of polymerization cannot be obtained, resulting in a gel-like state.

Furthermore, in order to obtain a polymer molded product with a high surface smoothness, it is necessary to use an expensive mold with a high surface smoothness.

Means for Solving the Problems> An object of the present invention is to solve the problems in the prior art and to provide a pipe forming method that can produce pipes with excellent weather resistance, chemical resistance, hardness, optical properties, and surface smoothness. It is about providing.

That is, the present invention provides a mold that is installed in a centrifugal molding machine that performs pipe forming by centrifugal force, containing a monomer or oligomer containing a diallyl compound and/or a di(meth)acrylic compound as an essential component, or a mixture thereof. The polymerizable substance (A) and the polymerizable substance (A
) and a liquid substance (C) having a density smaller than the polymerizable substance (A>) is present, and the polymerizable substance (A) is polymerized under centrifugal force to form a pipe. Provided is a pipe forming method characterized by forming a pipe into a shape.

In addition, a polymerizable product containing a monomer or oligomer or a mixture thereof containing a diallyl compound and/or a di(meth)acrylic compound as an essential component is placed in a mold installed in a centrifugal molding machine that performs pipe forming by centrifugal force. A substance (A) is put in, the surface of the polymerizable substance (A) is brought into contact with an inert gas atmosphere having an oxygen concentration of 1% or less, and the polymerizable substance (A) is polymerized under centrifugal force to form a pipe. Provided is a pipe forming method characterized by forming a pipe into a shape.

A diallyl compound and/or di(
A polymerizable substance (A) containing a monomer or oligomer containing a meth)acrylic compound as an essential component, or a mixture thereof; and a polymerizable substance (A) in which the solubility of the polymerizable substance (A) is low, and the polymerizable substance (A) A liquid substance (C) having a lower density and a liquid substance (B) having a density greater than that of the polymerizable substance (A) are present, and the polymerizable substance (A) is produced under centrifugal force. Provided is a pipe forming method characterized by polymerizing to form a pipe shape.

The polymerizable substance (A) is an aliphatic compound represented by the following formula (I) (wherein R is a residue of a dihydric alcohol, and the value of n or the average value of n is 1 to 10). , monomers or oligomers of di(allyl carbonate) of cycloaliphatic or aromatic dihydric alcohols or mixtures thereof.

The liquid material (C) preferably has a number average molecular weight (vrn)
500 to 5000 ethylene/α-olefin random copolymer oil.

In the present invention, monomers, oligomers, or mixtures thereof that contain diallyl compounds and/or di(meth)acrylic compounds as essential components include monomers alone, oligomers alone, mixtures of monomers and oligomers, and two or more types of monomers. , a mixture of two or more oligomers, or a mixture of one or more monomers and one or more oligomers.

Furthermore, in the present invention, the polymer may be a homopolymer or a copolymer.

<Structure of the invention> The present invention will be explained in detail below.

A preferred embodiment of the pipe forming method of the present invention is shown in FIGS. 1-3.

The pipe forming method of the present invention is a method for polymerizing a polymerizable substance (A) containing a diaryl compound and/or a di(meth)acrylic compound as an essential component, an oligomer, or a mixture thereof. Yes, and can be shown in three ways:

The first invention shown in FIG. 1 preferably contains a polymerizable substance (A) and a liquid substance (C) simultaneously or Place them separately and seal with flange 6, etc. This mold 1 is rotated, for example, in five rotational directions 7 around the cylindrical axis shown in FIG. Due to the centrifugal force caused by this rotation, the polymerizable substance (A) and the liquid substance (C) are separated into a cylindrical shape in the mold 1 due to the difference in their specific gravity, and the polymerizable substance (A) with a heavy specific gravity is separated into a cylindrical shape.
The inner surface of N2 is covered with a layer 3 of a liquid material (C) having a light specific gravity, and is held in a cylindrical shape. In this state, the polymerizable substance (A) is polymerized by heating or the like.

When the polymerizable substance (A) is in contact with air, active radicals are consumed by oxygen, and the molecular weight of the surface of the polymer that comes into contact with air does not increase and remains a viscous liquid or gel. The hardness may be inferior to that of the inside of the polymer.
Even if the atmosphere inside the mold 1 is replaced with an inert gas in advance, commercially available industrial inert gases have a considerably high oxygen content, and such problems cannot be avoided.

When the method of the first invention described above is used, the polymerizable substance (A)
Since the surface of layer 2 is covered with liquid (C) layer 3 and polymerized,
A polymer whose surface hardness is sufficiently high can be obtained. Furthermore, it is possible to sufficiently follow shape deformation due to resin contraction during polymerization, and a polymer with little internal strain can be obtained.

In the second invention shown in Fig. 2, a polymerizable substance (A) is placed in a mold l installed in a centrifugal forming machine that performs pipe forming by centrifugal force, and an inert material with an oxygen concentration of 1% or less is placed on the surface of the polymerizable substance (A). A gas 15 is brought into contact. Preferably, it is a pipe forming method in which a polymerizable substance is polymerized under centrifugal force to form a pipe shape while introducing an inert gas.

The inert gas atmosphere has an oxygen concentration of 1% or less, preferably 0.
．． The amount of inert gas is 5% or less, more preferably 0.01% or less.

When polymerizing the polymerizable substance (A), when the polymerizable substance (A) is in contact with air, active radicals are consumed by oxygen, so the molecular weight of the surface of the polymer that comes into contact with air does not increase. May remain as a viscous liquid or gel.

In order to complete the polymerization uniformly and have a surface hardness of 2B or higher in terms of pencil hardness, preferably HB or higher, the oxygen concentration of the atmosphere in which the polymerization is carried out is 1% or less, preferably 0.5% or less,
More preferably, 0.01% or less of an inert gas such as nitrogen or argon is used.

When the method of the second invention described above is used, a polymer having sufficiently high surface hardness can be obtained as in the first invention, and the internal strain of the polymer is also small.

The third invention shown in FIG. 3 preferably contains a polymerizable substance (A), a liquid substance (C), and a liquid substance ( B)
and are inserted simultaneously or separately and rotated in the rotation direction 7 as in the first invention. The centrifugal force caused by this rotation causes the polymerizable substance (A) layer 2, liquid material (C) layer 3, and liquid material (B) layer 4 to
is separated into a cylindrical shape in the mold 1 due to the difference in specific gravity, and while maintaining the cylindrical shape, the liquid material (C) layer 3 covers the inner surface of the polymerizable material (A) layer 2 and the outer surface. Liquid (B
) is polymerized with layer 4 covering.

By using the above-mentioned method of the third invention, not only can a polymer surface with sufficiently high hardness and low internal strain be obtained, but also the smoothness of the outer surface of the polymer is lower than that of the inner surface of mold 1. Sufficiently high smoothness can be obtained regardless of the unevenness of the surface.

Furthermore, it is easy to take out the polymer from the mold 1, and there is no unnecessary distortion when taking it out.

In the second invention, a liquid substance CB is further added to the mold l.
) can also be used to obtain the same effect as the third invention.

The diallyl compound used in the polymerizable substance (A) used in the present invention is not particularly limited as long as it is a diallyl compound, but examples include the following.

Aliphatic, cycloaliphatic or aromatic represented by the general formula (wherein R is the residue of a dihydric alcohol, and the value of n or the average value of n is 1 to 10 (preferably 2 to 10)) Examples include compositions (■) containing di(allyl carbonate) dihydric alcohols or oligomers or mixtures thereof (a)';

Component (a)' is preferably the reaction product of diallyl carbonate and dihydric alcohol in a molar ratio of 4:1 or less, more preferably in a molar ratio of 2:1.

The dihydric alcohol is preferably ethylene glycol,
1.3-propanediol, 1゜4-butanediol,
1.6-hexanediol, diethylene glycol, polyethylene glycol, dipropylene glycol, propylene glycol, neopentyl glycol, trimethylbentanediol, cyclohexane dimetatool, bis(hydroxymethyl)tricyclodecane, 2,7-norbornanediol, a.

One or more of α'-xylene diol, 1,4-bis(hydroxyethoxybenzene) and 2,2-bis[4-(hydroxyethoxy)phenyl]propane is used.

The polymerizable substance (A) preferably contains the component (a) shown below.
)'' (b) A liquid composition (■)' containing !3 and (c) is preferable, and the description of JP-A-59-140214 is cited and included herein.

Component (a)" is represented by the formula: (wherein R is a residue of a dihydric alcohol, and the value of n or the average value of n is from 1 to 10 (preferably from 2 to 10)) Oligomers or oligomer mixtures of di(allyl carbonate) of aliphatic, cycloaliphatic or aromatic dihydric alcohols (provided that di(allyl carbonate) monomers of dihydric alcohol optionally contained in the oligomer in the above formula) from 10 to 90% by weight, component (b) is of the formula - where R'' is the residue of a dihydric or trihydric alcohol and n'' is 2 or 3. di- or tri(allyl carbonate) monomer or mixture of aliphatic, cycloaliphatic or aromatic dihydric or trihydric alcohol represented by di(allyl carbonate) oligomer or poly(allyl carbonate) of the alcohol is not more than 30% by weight), - formula (wherein R'' is the residue of a dicarboxylic acid or tricarboxylic acid, and n'' is 2 or 3 ), O to 90% by weight of a compound selected from triallyl cyanurate and triallyl incyanurate, and component (C) are allyl esters of aliphatic or aromatic dicarboxylic acids or tricarboxylic acids represented by The total amount of compounds (b) and (c) is greater than O.

Component (a)" is preferably the product of the reaction of diallyl carbonate and dihydric alcohol in a molar ratio of 4:1 or less, preferably 2:1, wherein the dihydric alcohol is ethylene glycol, l3 -propanediol, 1
．． 4-butanediol, 16-hexanediol, diethylene glycol, polyethylene glycol, dipropylene glycol, propylene glycol, neopentyl glycol, trimethylbentanediol, cyclohexane dimetatool, bis(hydroxymethyl)tricyclodecane, 27-norbornanediol, a ,a'-
Preferably it is selected from xylene diol, 14-bis(hydroxyethoxybenzene), and 2,2-bis[4-(hydroxyethoxy)phenyl]propane.

Component (b) is a molar ratio of diallyl carbonate to dihydric or trihydric alcohol of 6:1 or more, preferably 12:1.
Preferably, the dihydric or trihydric alcohol is ethylene glycol, 1,3-propanediol, 14-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, dipropylene glycol, Bilene glycol, neopentyl glycol, trimethylbentanediol, cyclohexane dimetatool, bis(hydroxymethyl)tricyclodecane, 2,7-norbornanediol, α,α′-xylene diol, 1,4-bis(hydroxyethoxybenzene) , 22-bis[4-(hydroxyethoxy)phenyl]propane, trimethylolpropane, and tri(hydroxyethyl) incyanurate, or one or more of them are preferred.

In addition, component (b) includes diallyl phthalate, diallyl succinate, diallyl adipate, diallyl chlorendate,
Preferred are diallyl glycolate, diallylnaphthalene dicarboxylate and triallylmeritate.

Component (c) is preferably one or more of vinyl acetate, vinyl benzoate, methyl methacrylate, phenyl methacrylate, methyl acrylate, methyl maleate, maleic anhydride, and vinylidene chloride.

Further, the polymerizable substance (A) is preferably diethylene glycol bisallyl carbonate, 14bis(hydroxyethoxy)benzenebisallyl carbonate, 2,4
Examples include copolymerizable compositions of bisallyl compounds such as dichloroterephthalic acid bisallyl ester and vinyl monomers having an aromatic ring such as phenyl methacrylate and benzyl methacrylate.

Copolymerizable composition (I) of nuclear halogen-substituted benzenedicarboxylic acid with sialylene glycol diallyl carbonate described in JP-A No. 59-45312; Esters of nuclear halogen-substituted benzenedicarboxylic acid described in JP-A-59-8709 (e.g., 2,4-dichloroterephthalic acid bisallyl ester, etc.) and a radically polymerizable aromatic ring-containing monofunctional monomer having a refractive index of 1.55 or more as a homopolymer ( Copolymerizable composition (II) with one or more types of phenyl methacrylate), specific bisallyl carbonate or bisβ-methylallyl carbonate described in JP-A-59-8710 [e.g. .4-bis(hydroxyethoxy)benzenebisallyl carbonate, etc., and a radically polymerizable aromatic ring-containing monofunctional monomer having a refractive index of 1.55 or more as a homopolymer (e.g. A copolymerizable composition (such as phenyl methacrylate, etc.)
III), a monool (e.g. 4-benzyl-phenol) and an unsaturated carboxylic acid (
chloride) [for example, acrylic acid (chloride)] and the homopolymer has a refractive index of 1.55.
Copolymerizable composition (rV) with the above radically polymerizable monomer (e.g. styrene), JP-A-5
Copolymerizability of copolymerization of allyl ester of chlorobenzoic acid (e.g. diallyl 23-dichlorobenzoic acid) with a bifunctional monomer (e.g. diallyl ester of tetrabromophthalic acid) described in No. 9-96113 Composition (V
) A copolymerizable composition (Vl) with the copolymerization described in JP-A-59-184210 and diethylene glycol bisallyl carbonate (■) are exemplified.

The di(meth)acrylic compound used as the polymerizable substance (A) is not particularly limited, but di(meth)acrylates represented by the following structural formula are preferably used.

Here, R is H or CHs, and A represents the following formula.

-O-(CH,), -0- Other monomers and other fillers can be added to the polymerizable substance (A) to the extent that the physical properties of the resulting polymer are not impaired. For example, mono(meth)acrylic compounds, monoallylic compounds, or unsaturated carboxylic acids such as maleic anhydride in proportions of up to 30% by weight based on the polymer, or vinyltriethoxysilane in proportions of up to 10% by weight. A silane coupling agent can also be added.

In the method of the present invention, the polymerizable substance (A) may contain a polymerization initiator.

As the polymerization initiator used when polymerizing the polymerizable substance (A), any one may be used, such as a photopolymerization initiator, a thermal polymerization initiator, a combined photo/thermal polymerization initiator, or a combination thereof.

In addition to photopolymerization initiators, photopolymerization initiators include electron beam and radiation polymerization initiators.

Examples of the photopolymerization initiator include 2-hydroxy-2-methyl-1-phenyl-propan-1-one.

As a thermal polymerization initiator, peroxydicarbonates such as diisopropyl peroxydicarbonate, di-secandabutyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, and tertiary butyl perbenzoate;
Penzoyl beoxide, acetyl peroxide, t-
Butyl hydroperoxide, cumene hydroperoxide, di-t-butyl peroxide, peroxybenzoic acid
Organic peroxides and inorganic peroxides such as t-butyl, lauroyl peroxide, diisopropyl peroxydicarbonate, methyl ethyl ketone peroxide, and diacyl peroxides, and radical initiation such as azobisisobutyronitrile and azobismethylisovaleronitrile. Examples include agents.

Examples of the photo/thermal polymerization initiator include the following formula: The following compounds are mentioned.

The amount of the polymerization initiator used when polymerizing the polymerizable substance (A) is 0.1 to 10w based on the polymerizable substance (A).
t%, preferably 1 to 6 wt%.

The polymerizable substance (A) may be used in a semi-cured state (B stage) if necessary.

The liquid material (C) used in the present invention may be any liquid material as long as it has low solubility with the polymerizable substance (A) and has a density lower than that of the polymerizable substance (A).

The density of the liquid material (C) is preferably 0.7 to Ig/cm
"More preferably 0.8 to 0.95 g/cm"
It is better to

The liquid substance (C) may form a layer for sealing the open portion of the polymerizable substance (A) and blocking oxygen, and therefore a substance having low solubility with the polymerizable substance (A) is used.

The liquid substance (C) is, for example, water, and since water has a high vapor pressure, it is suitable for polymerizing the polymerizable substance (A) at a relatively low temperature.

It may also be a low molecular weight liquid synthetic hydrocarbon polymer or a liquid hydrocarbon mixture such as mineral oil.

Examples of synthetic hydrocarbon polymers include poly(α-olefin) oils such as polydecene-1, alkyl aromatic oils such as alkylbenzene, polybutene oil (liquid polybutene), polyhexene, and 2,4-dicyclohexyl-2-methylpentane. Alkylnaphthene oils such as oils, and ethylene/α-olefin random copolymerization systems such as ethylene-propylene random copolymerization oils are used.

Among these, those having a molecular weight of 500 or more, preferably 1000
~10,000 is preferred.

Furthermore, the number average molecular weight (TX n ) is 500 to 5000
In particular, an ethylene/α-olefin random copolymer system having a molecular weight of 1,500 to 3,000 is preferred.

It also consists of 30 to 70 mol% of ethylene component units and 30 to 70 mol% of α-olefin component units, has a number average molecular weight (7Vn) in the range of 1000 to 5000, and has a Q
A liquid low molecular weight ethylene/α-olefin copolymer having a value (weight average molecular weight/number average molecular weight) of 3 or less is preferred.

When a liquid polyolefin or the like is used as the liquid material (C), the liquid polyolefin can be easily removed after polymerization using an organic solvent such as hexane, kerosene, or trichlene.

The liquid material (B) is not particularly limited as long as it has low solubility with the polymerizable substance (A) and has a density greater than that of the polymerizable substance (A).

In this case, the solubility of the liquid material (B) in the polymerizable substance (A) must be kept low to the extent that it does not adversely affect the transparency, weather resistance, surface properties, etc. of the resin to be formed. When expressed in terms of solubility, it is usually 5% or less, preferably 3% or less.

When the solubility is like this, the hardness of the outer surface of the obtained polymer is particularly high.

In addition, the density of the liquid material (B) is not particularly limited, but is usually 1
．． 1 or more, preferably about 1.1 to 1.5.

A preferable example of such a raft-like substance (B) is an aqueous solution of metal halides, sulfates, nitrates, etc., and inorganic salts such that the density is 6 greater than that of the polymerizable substance (A) used. Examples include metals that are liquid at room temperature, such as mercury, after adjusting their concentration. Polymerization can be carried out under various conditions depending on the composition of the polymerizable substance (A) and the polymerization initiator used.

Examples of the mold used are cylindrical bodies such as iron pipes, stainless steel pipes, aluminum tubes, glass tubes, and hard PVC pipes, and the inner surface is preferably polished and plated to further improve surface accuracy.

It is preferable to purge the air in the mold with an inert gas in advance, and it is better to apply gas pressure or keep the gas flowing so that the inert gas in the mold reaches the desired pressure during polymerization. good.

Polymerizable substance (A), liquid substance (C) and raft-like substance (B)
may be mixed in advance, or may be poured separately into the mold.

The mold is placed in a centrifugal molding machine and rotated to polymerize the polymerizable substance (A) inside.

The centrifugal force varies depending on the type and amount of the polymerizable substance (A).

In thermal polymerization, the temperature varies depending on the shape and size, but for example, the mold may be placed in a heating tank or exposed to brodalum-controlled steam at 30 to 150°C, preferably 40°C.
~90°C, 0.5 to 72 hours, preferably 2 to 7 hours,
It is best to heat it. In photopolymerization, for example, 60 W/cm
~150 W/cm under high pressure mercury lamp for 1~2 hours, preferably 3~30 minutes, 40~120°C, preferably 60~
It is preferable to polymerize at 100°C.

The pipe obtained by the molding method of the present invention has a highly homogeneous surface with high hardness and smoothness without distortion, and has excellent chemical resistance and optical properties, making it widely used in gasoline rotameter etc. be able to.

<Example> The present invention will be specifically explained below using Examples.

(Example 1) The inner surface of an iron pipe with an inner diameter of 20 mm, an outer diameter of 30 mm, and a length of 500 mm was polished and nickel plated to give a surface accuracy of R.
It was used as a mold for a centrifugal cast molding machine with a=2 μm.

The inside of this mold was filled with N2 gas (oxygen concentration 5%) in advance.
), and here the following polymerizable substance (A)-1,50g
Then, 35 g of liquid (C)-1 was injected.

A good pipe was molded in 7 hours while rotating the mold and applying warm water program-controlled at a temperature of 50 to 90° C. and a flow rate of 20 β/min.

(A)-1 Diallyl carbonate and diethylene glycol were mixed in a molar ratio of 2:1 in the presence of sodium ethoxide.
6-133246 (30 wt% is diethylene glycol bisallyl carbonate, 70 wt% is oligocarbonate, n
= 3 to 10) Tris(allyl carbonate) of tris(hydroxyethyl) incyanurate prepared by reacting 55% by weight diallyl carbonate and tris(hydroxyethyl) isocyanurate at a molar ratio of 12:1 ) ・・・・・・
12.4% by weight diethylene glycol bisallyl carbonate 27.5% by weight Vinyl acetate 5% by weight Polymerization initiator (based on 100 parts by weight) Diisopropyl peroxydicarbonate...・2.5 parts by weight (C-1) Liquid ethylene/propylene copolymer (Mn2500, Q
value 2.0, specific gravity 0.846) (Example 2) Using the following (A)-2 as a polymerizable substance, a liquid material (C
A pipe with a smooth surface was molded in the same manner as in Example 1, except that 40 g of liquid material (B)-1 was injected into the mold in addition to )-1.

(A)-2 Prepared by reacting diallyl carbonate and diethylene glycol at a molar ratio of 2:1 in the presence of sodium ethoxide under the conditions described in JP-A-56-133246 (30 wt% is diethylene glycol, Bisallyl carbonate, 70 wt% is oligocarbonate, n=3-10) Isocyanuric acid prepared by reacting 58 wt% diallyl carbonate with tris(hydroxyethyl) isocyanurate at a molar ratio of 12:1 Tris (allyl carbonate) of acid tris (hydroxyethyl)...
・13% by weight diethylene glycol bisallyl carbonate 29% by weight Polymerization initiator (based on 100 parts by weight) Diisopropyl peroxydicarbonate 2.7 parts by weight (B)-1 Magnesium chloride aqueous solution adjusted to density 1, 30 (Example 3) Same as Example 1, but without injecting liquid (C)-1, the atmosphere in the mold was adjusted to an oxygen concentration of 0.01%. A good pipe was molded by replacing the gas with N2. Oxygen concentration was measured by the carbani cell method.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the molding method of the present invention. FIG. 2 is a sectional view showing another embodiment of the molding method of the present invention. FIG. 3 is a sectional view showing another embodiment of the molding method of the present invention. <Effects of the Invention> According to the pipe forming method of the present invention, polymerization shrinkage progresses evenly during polymerization, so internal distortion of the obtained molded product is extremely reduced. In addition, it is easily polymerized into a molded product with a high surface smoothness, and the mold can be easily removed. Moreover, sufficient hardness can be obtained both on the surface and inside of the molded product. Explanation of symbols 1...Mold, 2...Polymerizable substance (A) layer, 3...Liquid material (C) layer, 4...Liquid material (B) layer, 5...Inert gas , 6...Flange, 7...Rotation direction, 15...Inert gas

Claims (5)

[Claims] (1) Polymerization containing a monomer or oligomer or a mixture thereof containing a diallyl compound and/or di(meth)acrylic compound as an essential component in a mold installed in a centrifugal molding machine that performs pipe forming by centrifugal force. under centrifugal force in the presence of a polymerizable substance (A) and a liquid substance (C) in which the solubility of the polymerizable substance (A) is low and the density is lower than that of the polymerizable substance (A), A pipe forming method characterized by polymerizing the polymerizable substance (A) to form a pipe shape. (2) Polymerization containing a monomer or oligomer or a mixture thereof containing a diallyl compound and/or a di(meth)acrylic compound as an essential component in a mold installed in a centrifugal molding machine that performs pipe forming by centrifugal force. the surface of the polymerizable substance (A) is brought into contact with an inert gas atmosphere having an oxygen concentration of 1% or less, and the polymerizable substance (A) is polymerized under centrifugal force; A pipe forming method characterized by forming into a pipe shape. (3) Polymerization containing a monomer or oligomer or a mixture thereof containing a diallyl compound and/or a di(meth)acrylic compound as an essential component in a mold installed in a centrifugal molding machine that performs pipe forming by centrifugal force. a liquid substance (C) having a low solubility in the polymerizable substance (A) and a density lower than that of the polymerizable substance (A); Polymerize the polymerizable substance (A) under centrifugal force in the presence of a liquid substance (B) with low solubility and a higher density than the density of the polymerizable substance (A) to form a pipe shape. A pipe forming method characterized by: (4) The polymerizable substance (A) has the following formula (I)
) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R is the residue of a dihydric alcohol, and the value of n or the average value of n is 1 to 10) Aliphatic, alicyclic, or aromatic The pipe forming method according to any one of claims 1 to 3, which contains a di(allyl carbonate) monomer or oligomer of dihydric alcohol, or a mixture thereof. (5) The pipe forming method according to any one of claims 1 to 4, wherein the liquid material (C) is an ethylene/α-olefin random copolymer oil having a number average molecular weight (@M@n) of 500 to 5,000. .