JP2595182B2 - Polymerization method of vinyl chlorides - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to an improved method for polymerizing vinyl chloride by an emulsion polymerization method in an aqueous medium.

[0002]

2. Description of the Related Art Vinyl chloride resin is easily oxidized and degraded by oxygen in the air, and is often supplied to the market with an antioxidant added thereto.

[0003] Usually, an antioxidant is added during the production of a compounded powder, but it is difficult to mix uniformly. Therefore, it is added during the production of a vinyl chloride resin before, during, or after polymerization. Attempts have also been made. In particular, it is desirable to add the vinyl chloride resin when it is in a molten state or an emulsified state because the antioxidant is uniformly dispersed.

The antioxidants include phenol-based antioxidants, amine-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants and the like, and these are usually powders. It is difficult to charge them. In particular, when the vinyl chloride resin is in a molten state or an emulsified state, the inside of the system is under pressure, and it is more difficult to quantitatively inject the powdered antioxidant.

[0005]

The above problems based on the fact that these antioxidants are powders can be solved by dissolving the antioxidants in an appropriate organic solvent and using them. When the solvent is contained or the solvent needs to be recovered and added to the reaction system,
When unreacted monomer or polymerization solvent is recovered, there is a problem that the unreacted monomer or polymerization solvent is mixed into the recovered monomer or polymerization solvent. In addition, when suspension polymerization or emulsion polymerization is carried out in an aqueous medium such as vinyl chloride, the solvent used to dissolve the antioxidant is discharged into the wastewater, so that the COD in the wastewater increases. is there.

When emulsion polymerization is carried out in an aqueous medium, an antioxidant soluble in alkaline water such as bisphenol A can be used by dissolving or suspending in a caustic soda solution or caustic potash solution. Antioxidants soluble in alkaline water are extremely limited and cannot be applied to water-repellent antioxidants. In addition, when the antioxidant is brought into contact with alkaline water, phenol-based ones have a quinone structure, and have a disadvantage that they are colored and the resulting vinyl chloride resin is colored.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in such a situation, and surprisingly found that the antioxidant was pulverized to a fine powder, and the antioxidant was pulverized into water using an emulsifier and / or a suspending agent. It has been found that if dispersed as a fine powder, it can be easily added to the polymerization tank by a pump during the emulsion polymerization of vinyl chloride, and the present inventors have further studied and completed the present invention.

An object of the present invention is to provide a method for emulsion polymerization of vinyl chlorides, in which an antioxidant can be automatically charged and a vinyl chloride resin having improved heat stability can be obtained.

That is, the present invention relates to a method of polymerizing vinyl chloride by an emulsion polymerization method in an aqueous medium, wherein a powdery antioxidant is finely dispersed in water by an emulsifier and / or a suspending agent during polymerization of vinyl chloride. A method for polymerizing vinyl chloride, comprising adding an emulsion dispersed as a fine powder and uniformly dispersing an antioxidant in the resulting vinyl chloride resin.

In the present invention, the vinyl chlorides include not only vinyl chloride alone but also a mixture with a monomer copolymerizable with vinyl chloride.

Examples of monomers copolymerizable with vinyl chloride include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-
Octene, 1-nonene, 1-decene, 1-undecene,
Α-olefins having 2 to 30 carbon atoms such as 1-dodecene, 1-tridecene, 1-tetradecene, acrylic acid and its esters, methacrylic acid and its esters, maleic acid and its esters, vinyl acetate, vinyl propionate And vinyl compounds such as alkyl vinyl ethers, and mixtures thereof.

In the aqueous emulsion polymerization of vinyl chloride, the ratio of vinyl chloride to water is generally 80 to 300 parts by weight of water per 100 parts by weight of vinyl chloride, and the polymerization temperature is usually 35 to 70 ° C. is there.

Examples of the polymerization initiator that can be used include, for example,
Diisopropyl peroxy dicarbonate, dioctyl peroxy dicarbonate, dilauryl peroxy dicarbonate, dicetyl peroxy dicarbonate, ditertiary butyl peroxy dicarbonate, di (2-
Ethoxyethyl) peroxydicarbonate, di (2-
Methoxypropyl) peroxydicarbonate such as peroxydicarbonate, dibenzylperoxydicarbonate, dicyclohexylperoxydicarbonate, ditertiarybutylcyclohexylperoxydicarbonate, 2.2′-azobis2.4-dimethylvaleronitrile 2.2'-azobis-4-methoxy-2.
Azo compounds such as 4-dimethylvaleronitrile, tertiary butyl peroxy neodecaneate, α-cumyl peroxy neodecaneate, tertiary octyl peroxy neodecaneate, tertiary butyl peroxy pivalate, α-cumyl peroxy Peroxides such as pivalate, amyl peroxypivalate, di-tert-butyl oxalate, isobutyryl peroxide, water-soluble peroxides such as hydrogen peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, sodium perborate, etc. And these may be used in combination in order to make the polymerization reaction rate uniform.

The emulsifier used in the emulsion polymerization method includes
Anything that is usually used for the polymerization of paste resins can be used without any problem.
Anionic surfactants such as alkyl allyl sulfonate, alkyl alcohol sulfate, fatty acid salt, and dialkyl sulfosuccinate are exemplified. These emulsifiers are usually used in one kind or in two or more kinds. As these salts, alkali metals are generally used.

In the emulsion polymerization method, an emulsifying aid is used in addition to the above-mentioned anionic surfactant, and glycerin ester, glycol ester or sorbitan ester of higher fatty acid, higher alcohol condensate, higher fatty acid condensate, polypropylene condensate Nonionic surfactants such as products, higher alcohols such as cetyl alcohol and lauryl alcohol, higher fatty acids such as lauric acid, palmitic acid and stearic acid or esters thereof and the like can be used in combination with the anionic surfactant. .

In the emulsion polymerization method, aromatic hydrocarbons,
PH of higher aliphatic hydrocarbons, halogenated hydrocarbons such as chlorinated paraffin, sodium bicarbonate, ammonia, etc.
Normal polymerization aids such as regulators and chain transfer agents may be used in combination.

In the emulsion polymerization method, an emulsifier, a polymerization initiator,
Water, vinyl chlorides and, if necessary, other polymerization auxiliaries are premixed prior to the polymerization reaction and then homogenized by applying high shear. This homogenization is performed by a known homogenization method such as a one-stage or two-stage pressurized high-pressure pump, a colloid mill, a homomixer, a high-pressure jet from a nozzle or an orifice, and a method using ultrasonic waves.

In the present invention, it is necessary to add a milk suspension in which a fine powdered antioxidant is dispersed in water as a fine powder during the emulsion polymerization of vinyl chlorides. By dispersing the inhibitor as a fine powder in water using an emulsifier and / or a suspending agent, it can be stably automatically charged into a polymerization tank under pressure by a pump or the like.

The antioxidant used here is usually a solid, fine powder, which can be dispersed as fine powder in water by an emulsifier and / or suspending agent. As such, for example, 2.6-di-t-butyl-p-cresol (BH
T), 3-tert-butyl-4-hydroxy-anisole (3-BHA), 2-tert-butyl-4-hydroxy-anisole (2-BHA), 2.2'-methylenebis (4-
Methyl-6-t-butylphenol) (MBMBP),
2.2'-methylenebis (4-ethyl-6-t-butylphenol) (MBEBT), 4.4'-butylidenebis (3-methyl-6-l-butylphenol) (BBM
BP), 4.4'-thiobis (3-methyl-6-t-butylphenol) (SBMBP), styrenated-p-cresol, 1.1.3-tris (2-methyl-4-hydroxy-5-t) -Butylphenyl) butane, tetrakis [methylene-3- (3′.5′-di-t-butyl-4 ′)
-Hydroxyphenyl) propionate] methane, n-
Octadecyl-3- (4'-hydroxy-3 ', 5'-
Di-tert-butylphenyl) propionate, 1.3.5
-Trimethyl-2.4.6-tris (3.5-di-t-
Butyl-4-hydroxybenzyl) benzene, 2.2 '
-Dihydroxy-3.3-t-di (α-methylcyclohexyl) -5.5′-dimethyl-diphenylmethane,
4.4'-methylenebis (2.6-di-t-butylphenol), tris (3.5-di-t-butyl-4-hydroxyphenyl) isocyanurate, 1.3.5-tris (3 '. 5'-di-t-butyl-4-hydroxy-benzoyl) isocyanurate, bis [2-methyl-4-
{3-n-alkylthiopropionyloxy} -5-t
-Butylphenyl] sulfide, 1-oxy-3-methyl-isopropylbenzene, 2.5-di-t-butylhydroquinone, alkylated bisphenol, 2.5-di-t-amylhydroquinone, polybutylated bisphenol A, bisphenol A , 2.6-Bis (2'-hydroxy-3-tert-butyl-5'-methyl-benzyl)-
4-methylphenol, 1.3.5-tris (4-t-
Butyl-3-hydroxy-2.6-dimethylbenzyl)
Isocyanurate, terephthaloyl-di (2.6-dimethyl-4-tert-butyl-3-hydroxybenzylsulfide), 2.6-di-tert-butyl-α-dimethylamino-p-cresol, 2 .2'-methylene-bis (4-methyl-6-cyclohexylphenol), hexamethyleneglycolbis (3.5-di-tert-butyl-4-hydroxyphenyl) propionate, 6- (4-hydroxy- 3.5-di-t-butylanilino) -2,4-bis (octylthio) -1.3.5-triazine, 2.2-
Thio- [diethyl-bis-3- (3.5-di-tert-butyl-4-hydroxyphenyl) propionate], N.P.
N'-hexamethylenebis (3.5-di-t-butyl-
4-hydroxy-hydrocinamide), 3.5-di-t-
Butyl-4-hydroxy-benzyl-phosphoric acid diethyl ester, 2.4-dimethyl-6-t-butylphenol, 4.4-methylenebis (2.6-di-t-butylphenol), 4.4′-thiobis (2 -Methyl-6-t
-Butylphenol), tris [β- (3.5-di-t
-Butyl-4-hydroxyphenyl) propionyl-oxyethyl] isocyanurate, 2.4.6-tributylphenol, bis- [3.3-bis (4′-hydroxy-3′-t-butylphenyl) -butylic acid Glycol ester, 4-hydroxymethyl-2.
6-di-t-butylphenol, bis (3-methyl-4
Phenolic antioxidants such as -hydroxy-5-t-butylbenzyl) sulfite, N-phenyl-N'-isopropyl-p-phenylenediamine, N-phenyl-
N '-(1.3-dimethylbutyl) -p-phenylenediamine; Amine antioxidants such as N'-diphenyl-p-phenylenediamine, 2.2.4-trimethyl-1.2-dihydroquinoline polymer, diaryl-p-phenylenediamine, dilauryl thiodipropionate, distearyl -Sulfur-based antioxidants such as thiodipropionate and 2-mercaptobenzimidazole, and phosphorus-based antioxidants such as distearylpentaerythritol diphosphite, but are not limited thereto. These antioxidants are used alone or in combination of two or more.

These antioxidants can be dispersed in water by using an emulsifier alone, a suspending agent alone, or a combination of an emulsifier and a suspending agent. When the antioxidant is dispersed by an emulsifier alone, its particle size is preferably 10 μm or less. 99 μm or less of 5 μm
% Or more, when the suspending agent is used in combination, the particle size is 50 μm or less, and when the emulsifier and the suspending agent are used together, the particle size is 5 μm or more.
It is desirable that those having a thickness of 0 μm or less be 99% or more.
When more than these particle sizes increase, the antioxidant precipitates or floats and often causes phase separation,
It is often necessary to re-disperse when used.

In the present invention, the particle size distribution of the antioxidant dispersed in water was measured by a centrifugal automatic particle size distribution analyzer.

Usually, the concentration of the antioxidant in the emulsion is suitably from 70 to 1% by weight, and if it exceeds 70% by weight, the fluidity of the emulsion becomes poor, which is not preferable, and is less than 1% by weight. In such a case, a large amount of an emulsion must be added to add a predetermined amount of an antioxidant, which is not preferable. More preferably, it is 65 to 10% by weight. The amount of the emulsifier used in this case is preferably from 10 to 0.1% by weight in the emulsion, and the amount of the suspending agent when the suspending agent alone is dispersed is preferably from 10 to 0.5% by weight in the emulsion. % Is preferable, and when an emulsifier and a suspending agent are used in combination, the amount of the emulsifier in the emulsion is 10 to 0.1%.
It is preferable to add 1% by weight and the amount of the suspending agent to be 10 to 0.5% by weight in the emulsion.

The emulsifier used for dispersing the antioxidant may be any of anionic, amphoteric, cationic and nonionic.

Examples of the anionic emulsifier include lauric acid,
Fatty acids such as palmitic acid and stearic acid, acidic alkyl alcohol sulfates, paraffinsulfonic acid, alkylarylsulfonic acids (for example, dodecylbenzenesulfonic acid or dibutylnaphthalenesulfonic acid), and alkali metals such as sulfo-succinic acid dialkyl esters, alkaline earths Salts with metals or ammonium, as well as fatty acids containing epoxy groups such as epoxystearic acid, and peracids (eg peracetic acid) and unsaturated fatty acids (eg oleic acid or linoleic acid) or unsaturated oxyfatty acids (eg ritinoleic acid) And a salt with an alkali metal or ammonium such as a reaction product of the above. Examples of the amphoteric or cationic emulsifier include alkyl betaines such as dodecyl betaine, alkyl pyridinium salts such as lauryl pyridinium-hydrochloride, and alkyl ammonium salts such as oxyethyl-dodecyl-ammonium chloride.

As the nonionic emulsifier, glycerin-
Examples include fatty acid partial esters of polyhydric alcohols such as monostearate, sorbit-monolaurate and -oleate, polyoxyethyl esters of fatty acids or aromatic hydroxy compounds, and polypropylene oxide-polyethylene oxide-condensation products. These emulsifiers are used alone or in combination of two or more as necessary. Of these, a nonionic emulsifier is preferably used.

The proportion of the emulsifier in the emulsion is preferably from 10 to 0.1% by weight, more preferably from 5 to 0.5% by weight. 1
If it exceeds 0% by weight, the cost increases, which is not preferable. On the other hand, if it is less than 0.1% by weight, the storage stability of the emulsion becomes poor, which is not preferable.

Examples of suspending agents used for dispersing the antioxidant include polyvinyl alcohol, cellulose derivatives, maleic anhydride-styrene copolymer, maleic anhydride-methylvinyl ether copolymer, gelatin and the like.

The proportion of the suspending agent in the emulsion is preferably from 10 to 0.5% by weight, more preferably from 5 to 1% by weight. If it exceeds 10% by weight, the cost increases, which is not preferable.
If it is less than 5% by weight, the storage stability deteriorates, which is not preferable.

There is no particular limitation on the water used, but deionized water and distilled water are preferably used. The method of adding the antioxidant dispersed in water may be before polymerization, during polymerization, or after polymerization, but before polymerization, it is manually charged from a manhole of a polymerization machine or automatically charged by a pump, or the polymerization reaction is stopped. At times, charging is performed manually by a pot or automatically charged by a pump. In any case, automatic charging by a pump is preferable from the viewpoint of workability.

The addition ratio of the emulsion of the antioxidant is 0.0
01 to 1.0% by weight, preferably 0.002 to 2% by weight
Is more preferred. If the amount is less than 0.001% by weight, deterioration of the vinyl chloride resin cannot be prevented. If the amount is more than 1.0% by weight, it is necessary to increase the amount of the emulsion to be added.
This results in an increase in OD, which is not preferable.

[0031]

The present invention will be described more specifically with reference to examples and comparative examples.

Throughout the Examples and Comparative Examples, the Congo Red thermal stability of the vinyl chloride resin was determined as follows: 60 parts of dioctyl phthalate and 2 parts of T-72 (organotin) were added to 100 parts of the polymer to form a sol. For 10 minutes to prepare a film, which was measured according to JIS K6723.

Example 1 50 parts of powdery 4.4'-butylidenebis (3-methyl-6-tert-butylphenol) having a particle size of 10 μm or less consisting of 99.1% by weight, deionized water 48 parts, sorbit mono Two parts of laurate were placed in a stirring tank and homogenized with a homogenizer. The obtained emulsion had good flowability. This emulsion was used for the polymerization of vinyl chloride monomer.

In a polymerization machine having an internal volume of 1000 L, 450 kg of water was added.
Sodium lauryl sulfate 3 kg, lauryl alcohol 6 kg, α-cumyl peroxyneodecanate 0.1
2 kg, dioctyl peroxydicarbonate 0.06 kg
After the space was replaced with nitrogen, the pressure in the vessel was reduced and 300 kg of vinyl chloride was charged. 30 ° C inside container
And stirred and mixed for 30 minutes. Next, the liquid in the preliminary stirrer was homogenized with a pressurized homogenizer, and then charged into a 1000-L glass-lined polymerization reactor having a reduced pressure of 35 mmHg abs by a vacuum pump, and allowed to react at 50 ° C. When the pressure reached 5 kg / cm ² G, 1.5 kg of the above emulsion was injected into the polymerization machine using a mill flow pump and stirred, and then the unreacted monomer was recovered. After drying it was obtained as a product for grinding.

The heat stability of Congo Red of the obtained product was 80 minutes, and the same amount as in Example 1 was added to a vinyl chloride resin obtained by emulsion polymerization without adding the emulsion of the above-mentioned antioxidant. It was better than Congo Red heat stability (30 minutes) when 4.4'-butylidenebis (3-methyl-6-tert-butylphenol) was added.

Comparative Example 1 50 parts of powdery 4.4'-butylidenebis (3-methyl-6-tert-butylphenol) having a particle size of 10 μm or less consisting of 99.1% by weight and 50 parts of deionized water were placed in a stirring tank. The mixture was stirred with a homogenizer, but was not homogeneous, and the antioxidant floated on the water when the stirring was stopped. This product was pressed into the polymerization machine using a mill flow pump in the same manner as in Example 1, but only separated water was pressed into the polymerization machine.
Antioxidants could not be injected.

Example 2 Fine powder of bisphenol A40 having an average particle size of 50 μm
Parts, 57 parts of deionized water and 3 parts of sorbit monolaurate were placed in a ball mill, and pulverized and dispersed until the particles having a particle size of 5 μm or less became 99% by weight. The obtained emulsion had good flowability.

1.5 kg of the above emulsion was prepared in the same manner as in Example 1.
Was press-fitted, dried with a spray drier and pulverized to obtain a product. The Congo Red heat stability of the obtained product is 50 minutes, and is 30 minutes when the same amount of bisphenol A is added to the emulsion polymer obtained by performing emulsion polymerization without adding the emulsion of the above-mentioned antioxidant. It was better than a minute.

Comparative Example 2 10 parts of bisphenol A and 90 parts of methanol were placed in a stirring tank and stirred to dissolve.

An emulsion polymerization reaction of vinyl chloride was carried out in the same manner as in Example 2, except that 6.0 kg of this methanol solution was injected instead of the emulsion of Example 2.

The heat stability of Congo Red of the obtained product was 48 minutes, and the exhaust gas from the dryer contained a large amount of methanol, so that the exhaust gas had to be treated.

Example 3 In Example 2, emulsion polymerization was carried out using sodium lauryl sulfate instead of sorbit monolaurate to obtain a product.

The heat stability of Congo Red of the obtained product is 48 minutes. When the same amount of bisphenol A is added to the polymer powder obtained by polymerization without adding the water suspension of the above-mentioned antioxidant, It was better.

However, the volume resistivity of the obtained product was 0.43 × 10 ¹³ Ωcm, which was slightly inferior to that of Example 2.

Example 4 Powdered bisphenol A35 having an average particle size of 50 μm
Parts, 61 parts of deionized water, 2 parts of glycerin / monostearate, and 2 parts of partially saponified polyvinyl alcohol having a degree of saponification of 80 mol% and an average degree of polymerization of 2,000 were placed in a stirring tank, and homogenized with a homogenizer.
It was pulverized and dispersed until it became 5% by weight. The obtained emulsion had good fluidity. This emulsion was used for the polymerization of vinyl chloride monomer.

This emulsion 1.7 was obtained in the same manner as in Example 1.
kg was injected, dehydrated and dried, and a vinyl chloride resin was obtained as a product.

The heat stability of Congo Red of the obtained product is 55 minutes, which is smaller than that obtained by adding bisphenol A to the polymer powder obtained by polymerization without adding the water suspension of the above-mentioned antioxidant. It was excellent.

Example 5 Powdered bisphenol A35 having an average particle size of 50 μm
Parts, deionized water 62 parts, saponification degree 80 mol%, average polymerization degree 2000, 3 parts of saponified polyvinyl alcohol were placed in a stirring tank, and homogenized with a homogenizer to obtain a particle size of 50.
It was pulverized and dispersed until 9 μm or less became 99.5% by weight.
The obtained emulsion had good fluidity. This emulsion was used for the polymerization of vinyl chloride monomer.

This emulsion 1.7 was obtained in the same manner as in Example 1.
kg was injected, dehydrated and dried, and a vinyl chloride resin was obtained as a product.

The heat stability of Congo Red of the obtained product is 45 minutes, and when bisphenol A is similarly added to the emulsion polymer obtained by carrying out emulsion polymerization without adding the water suspension of the above-mentioned antioxidant. It was better.

Example 6 The emulsion of Example 1 was used for emulsion polymerization of a vinyl chloride monomer.

450 kg of water was placed in a polymerization machine having an internal volume of 1000 L,
Sodium lauryl sulfate 3 kg, lauryl alcohol 6 kg, α-cumyl peroxyneodecanate 0.1
2 kg, dioctyl peroxydicarbonate 0.06 kg
After the space was replaced with nitrogen, the pressure in the container was reduced and 300 kg of vinyl chloride was charged. Then, 1.5 kg of the emulsion of Example 1 was pressed into the polymerization machine using a mill flow pump, After stirring, keep the temperature in the container at 30 ° C,
Stir and mix for minutes. Next, the liquid in the preliminary stirrer was homogenized with a pressure homogenizer, and then 35 mmHg abs with a vacuum pump.
The reaction was carried out at 50 ° C. when the internal pressure reached 5 kg / cm ² G pressure.
After 5 kg was pressed into a polymerization machine using a mill flow pump and stirred, unreacted monomers were recovered, and the polymer latex was dried by a spray dryer and obtained as a product by pulverization.

The heat stability of Congo Red of the obtained product was 80 minutes, and the same amount as in Example 1 was added to a vinyl chloride resin obtained by emulsion polymerization without adding the above-mentioned antioxidant emulsion. It was better than Congo Red heat stability (30 minutes) when 4.4'-butylidenebis (3-methyl-6-tert-butylphenol) was added.

[0054]

Industrial Applicability According to the present invention, there is a great industrial value that a vinyl chloride resin having an improved anti-oxidant and capable of automatically charging an antioxidant can be obtained.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Patent Publication No. 44-2105 (JP, B1) Emulsion Latex Handbook Editing Committee, “Emulsion Latex Handbook,” First Edition (Showa 50-3-25) Taiseisha P. 428

Claims (4)

(57) [Claims] In a method of polymerizing vinyl chloride by an emulsion polymerization method in an aqueous medium, a powdery antioxidant is dispersed in water in a fine powder form by an emulsifier and / or a suspending agent during polymerization of vinyl chloride. A method for polymerizing vinyl chlorides, comprising adding an emulsion prepared as described above and uniformly dispersing an antioxidant in the resulting vinyl chloride resin. 2. The antioxidant dispersed in water in the form of a fine powder has a particle size of 10 μm or less, and the composition of the emulsion is 1 to 70% by weight of the antioxidant, 0.1 to 10% by weight of the emulsifier and 2. The method for polymerizing vinyl chloride according to claim 1, wherein the amount of water is 98.9 to 20% by weight. 3. An antioxidant dispersed in water in the form of a fine powder having a particle size of 50 μm or less, wherein the composition of the emulsion is 1 to 70% by weight of the antioxidant, 0.1 to 10% by weight of the emulsifier, The method for polymerizing vinyl chlorides according to claim 1, wherein the suspension is 0.5 to 10% by weight and water is 98.4 to 10% by weight. 4. The method for polymerizing vinyl chlorides according to claim 1, wherein the emulsifier is a nonionic emulsifier.