WO1999002572A1

WO1999002572A1 - Vinyl chloride resin granules for paste processing and process for producing the same

Info

Publication number: WO1999002572A1
Application number: PCT/JP1998/003047
Authority: WO
Inventors: Yoshimitu Nagatomo; Tatsuya Ozaki; Shousuke Kondou
Original assignee: Shin Dai-Ichi Vinyl Corporation
Priority date: 1997-07-07
Filing date: 1998-07-07
Publication date: 1999-01-21
Also published as: JP4059929B2

Abstract

Vinyl chloride resin granules for paste processing which are spherical agglomerates of primary vinyl chloride resin particles and which have an angle of repose of 30 to 38°, a proportion of spherical granules with a diameter not smaller than 20 νm of 60 wt.% or larger, an average particle diameter of 35 to 200 νm, and a bulk density (loose) of 0.59 to 0.65 g/cc. Preferably, the content of undispersible particles in the granules is 0.30 wt.% or lower. The resin granules are produced by a process comprising spray-drying an aqueous vinyl chloride polymer dispersion obtained by emulsion polymerization or fine suspension polymerization and recovering the polymer, wherein fine particles entrained by the discharge air in the spray-drying are removed separately from resin granules having a larger particle diameter.

Description

Description Vinyl chloride resin granules for paste processing and manufacturing method

The present invention has a high bulk density, powder flowability, and open-package, which are used for processing a paste produced from an aqueous dispersion of a vinyl chloride resin obtained by fine suspension polymerization or emulsion polymerization. The present invention relates to vinyl chloride resin granules having improved dust-preventing properties and plasticizer dispersibility, and a method for producing the same. Background art

Conventionally, polyvinyl chloride resin for paste processing has been manufactured as follows. That is, usually, vinyl chloride having a primary particle size of 0.1 to 5 m obtained by emulsion polymerization or fine suspension polymerization of vinyl chloride or a monomer mixture mainly composed of vinyl chloride in the presence of a surfactant. If necessary, 5 to 30% by weight of particles having a primary particle size of 0.2 to 2 zm of a surfactant or a polymer of the same type is added to the aqueous dispersion of the polymer, and then spray drying is performed. And dry.

After the above-mentioned spray drying, a comparison is made between resin condensate particles formed by collecting primary particles in droplets as a result of water vaporization of the spray droplets being collected from the bottom of the spray dryer chamber. Resin granules with a large particle size and fine particles with a small bulk density and particle size (such as resin granules) collected from the exhaust air from a spray dryer by a cyclone or bag filter or a combination thereof. (Eg, K. Masters: Chemical and Engineering Series, "Spray Drying", LEONARD HILL BOOKS LONDON) (1972), PI_8).

Conventionally, paste processing is usually performed by classifying and removing aggregates of resin granules and fragments of sediment on the wall surface of a dryer from the combined and mixed powder and granules, and then pulverizing. Plasticizer and, if necessary, heat It was mixed with compounding agents such as stabilizers and fillers to form plastisols (pastes).

The powder properties of the vinyl chloride resin for paste processing are governed by its shape. By improving the dispersibility of the plasticizer in the resin granules by lowering the spray-drying temperature than before, the above-mentioned pulverizing step can be omitted, and as a result, dust generated when the bag packing the resin is opened is reduced. The method of improving the deterioration of the work environment due to the generation of the resin and enabling the automatic metering and supply of the same resin powder, which has been difficult in the past, is disclosed in Japanese Patent Publication No. 3-7814, No. 6-5. It has been proposed in Japanese Patent Publication No. 831 and Japanese Patent Publication No. 6-712169. However, even in these methods, the vinyl chloride resin powder still contains fine particles collected by a cyclone or a bag filter or a combination thereof in the spray drying method as described above. Problems remain, such as dust being generated at the time of opening the bag and deteriorating the work environment. Moreover, the vinyl chloride resin granules produced by the proposed production method have insufficient plasticizer dispersibility, so that further improvement has been desired.

The prepared paste sol removes the resin granules and aggregates that are not dispersed in the plasticizer by means of a strainer or the like, and is heated and gelled through a process such as coating. Processed and made into a product. Resin granules are less dispersible in plasticizers than pulverized paste processing resins.Therefore, when preparing plastisols, it is necessary to take measures such as increasing the kneading strength or lengthening the kneading time compared to pulverized products. Was. There were also dangers such as the strainer clogging due to undispersed material and the incorporation of coarse particles into the coating sol.

According to Japanese Patent Publication No. Hei 6—5 5 8 3 1 No. 1 and Japanese Patent Publication No. Hei 6—7 2 169, a method for producing a granular product having improved dispersibility by spray drying at a low temperature is disclosed. Although the dispersibility was improved, there was a problem that the energy efficiency required for drying was much worse than that of the pulverized product. Disclosure of the invention

An object of the present invention is to provide a powder having a large bulk density, powder flowability, dust prevention at the time of bag opening, and An object of the present invention is to provide a vinyl chloride resin granule for paste processing with improved dispersibility of a plasticizer.

According to the present invention, the spherical granules are aggregates of primary particles of vinyl chloride resin, the angle of repose of which is 30 to 38 degrees, and the ratio of spherical granules having a diameter of 20 m or more is 60% by weight. As described above, there are provided vinyl chloride resin granules for paste processing characterized by having an average particle size of 35 to 200 / m and a bulk density (loose) of 0.59 to 0.65 g Zcc. Is performed.

The above vinyl chloride resin granules for paste processing preferably have an undispersed particle ratio of 0.30% by weight or less.

Further, according to the present invention, an aqueous vinyl chloride polymer obtained by emulsion polymerization or fine suspension polymerization of vinyl chloride or a monomer mixture mainly containing vinyl chloride in the presence of a surfactant is used. In the method for producing vinyl chloride resin granules, in which the dispersion is spray-dried to recover the salted polyvinyl resin granules, when the aqueous dispersion is spray-dried, the vinyl chloride resin fine particles accompanying the exhaust air are removed. The spherical granules are separated and removed independently of the granules, the angle of repose is 30 to 38 degrees, the ratio of the spherical granules having a diameter of 20 or more is 60% by weight or more, and the average particle size is 35 A method for producing bi-chloride resin granules for paste processing, which comprises collecting bi-chlor chloride resin granules having a bulk density (looseness) of 0.59 to 0.65 g / cc up to 200 m. Is provided.

In the above production method, in order to separate and remove the vinyl chloride resin fine particles accompanying the exhaust air independently of the vinyl chloride resin granules, it is preferable to use a damper provided in the exhaust air pipe and an empty space under the spray dryer chamber. A method of adjusting the opening of the damper provided on the carrying pipe is adopted. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a flowchart showing a drying step of vinyl chloride resin granules in a process for producing a salted vinyl resin granule for paste processing of the present invention.

2A and 2B are a side view and a front view, respectively, showing a stirring blade of a stirring device used for measuring an undispersed particle ratio. BEST MODE FOR CARRYING OUT THE INVENTION

The vinyl chloride resin granules of the present invention are aggregates of polymer particles having a primary particle size of 0.1 to 5 obtained by emulsion polymerization, fine suspension polymerization, etc. It has powder fluidity. In this aggregate, the proportion of spherical granules having a diameter of 20 m or more is 60 wt% or more, preferably 85 wt% or more, and the proportion of spherical granules having a diameter of 40 m or more is more than 60 wt%, particularly It is preferably at least 80% by weight and has an average particle size of 35 to 200 m, preferably 50 to 150 m.

Here, the term “spherical” is not limited to a true sphere, but also refers to a spheroid or a spheroid with a ratio of the major axis to the minor axis in the range of 1: 1 to 1: 0.8. This concept is included. The term “diameter” refers to the circular equivalent diameter (haywood diameter) and the sieving diameter, which can be determined in a methanol solvent using a laser diffraction particle sizer, or a sieving method using a JIS standard sieve. It is measured by.

Further, the vinyl chloride resin granules of the present invention have an angle of repose of 30 to 38 degrees, preferably 32 to 35 degrees, and a bulk density (loose) of 0.59 to 0.658 (::, preferably 0.60 to 0.638 f). The resin granules preferably have an undispersed particle ratio of 0.3% by weight or less, more preferably 0.2% by weight or less, based on the measurement method described below.

The vinyl chloride resin granules having the above properties have the following advantages. (B) Good powder fluidity, easy transportation by air or lorry, and automatic weighing and automatic supply during use can be easily performed without any problems.

(Mouth) There is a mass merit because the bulk density is extremely high. That is, the volume of the powder during movement and storage can be reduced.

(8) Since there is less fine powder, less dust is generated during weighing operations and bulk transport operations. (2) Blocking properties are improved due to less fine powder. Therefore, when the vinyl chloride resin granules of the present invention are withdrawn from the lower part of a silo, a hopper, or the like, a phenomenon that a bridge is formed and is not discharged is less likely to occur. (E) Further, those having a small undispersed particle ratio as described above have excellent paste processing compatibility because they have particularly good plasticizer dispersibility.

Hereinafter, the method for producing the vinyl chloride resin granules of the present invention will be described.

The vinyl chloride polymer used in the production of the vinyl chloride resin granules of the present invention is a monomer mixture comprising vinyl chloride or vinyl chloride as a main component and an unsaturated monomer copolymerizable therewith. By performing emulsion polymerization (including seeded emulsion polymerization) or fine suspension polymerization (including seeded fine suspension polymerization).

The emulsion polymerization or the fine suspension polymerization may be performed by a known method, and is not particularly limited. An aqueous dispersion of a vinyl chloride polymer is obtained by these methods, but the concentration is not particularly limited. Usually aqueous dispersions having a concentration of from 20 to 65% by weight, preferably of from 40 to 60% by weight, are used.

The composition of the vinyl chloride-based polymer is not particularly limited, but in the case of a copolymer, 50% by weight of a monoethylenically unsaturated monomer unit copolymerizable with 50% by weight or more of vinyl chloride units. What consists of the following is preferable. Monoethylenically unsaturated monomers that can be copolymerized with chlorovinyl include, for example, olefinic compounds such as ethylene and propylene; vinyl esters such as vinyl acetate and vinyl propionate; acrylic acid and methacrylic acid; Unsaturated monocarboxylic acids: methyl acrylate, ethyl acrylate, _n-butyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, methyl ethyl methacrylate, mono N, N-dimethyl methacrylate Unsaturated monocarboxylic acid esters such as aminoethyl; unsaturated amides such as acrylamide and methacrylamide; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated dicarboxylic acids such as maleic acid and fumaric acid; Esters and their anhydrides; N-substituted maleimides; Methyl ether, vinyl ether, such as Biniruechirue ether; vinylidene compounds such as and vinylidene chloride can be exemplified.

In emulsion polymerization, water is used as a medium, an anionic or nonionic surfactant, an emulsifier, and a water-soluble polymerization initiator are used. Sharp within the range of 0.05 to 0.5 m in diameter A microspherical polymer latex with a particle size distribution is obtained.

The seeding emulsion polymerization method is a polymerization method in which a polymer obtained by emulsion polymerization is used as a seed and is enlarged by polymerization of a monomer in an aqueous medium. In this polymerization method, the anionic surfactant for stabilizing the polymer particles is added in harmony with the progress of the polymerization reaction so that the amount does not exceed the amount required to cover the surface of the polymer particles. Is polymerized with a polymerization initiator. The resulting polymerization system usually contains, in addition to the enlarged main polymer particles having an average particle size of 0.9 to 1.3 m, a relatively small amount of an average particle size of 0.1 to 0.3 m. By-product polymer particles are mixed.

The fine suspension polymerization method is a method in which monomers are homogenized with an anionic surfactant using a homogenizer or the like in an aqueous medium in the presence of an oil-soluble polymerization initiator, and then polymerized under relatively gentle stirring. . According to this method, spherical polymer particles having a broad normal distribution-like particle size distribution of usually from 0.05 to about 2 im of primary particles are obtained.

The anionic surfactant used in the polymerization is not particularly limited. Examples thereof include alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate; alkyl sulfates such as sodium lauryl sulfate and sodium tetradecyl sulfate; Sulfosuccinates such as sodium silicate and sodium dihexyl sulfosuccinate; Fatty acid salts such as sodium laurate and potassium potassium semi-hardened tallow fatty acid; Sodium polyoxyethylene lauryl ether sulfate; Polyoxyethylene nonylphenyl sulfate Ethoxysulfate salts of alkane sulfonates; alkyl ether phosphate esters; and the like. The amount of the anionic surfactant used depends on the polymerization method to be used, but is usually selected from the range of 0.2 to 2.5 parts by weight per 100 parts by weight of the monomer. In addition to the anionic surfactant, polyoxyethylene nonylphenyl ether may be appropriately used in combination. It is also possible to add a lipophilic auxiliary emulsifier such as a higher alcohol or sorbyster stearyl ester in emulsion polymerization, fine suspension polymerization and the like.

The polymerization initiator may be water-soluble or oil-soluble. Water-soluble polymerization Examples of the initiator include water-soluble compounds such as potassium persulfate, ammonium persulfate, and hydrogen peroxide; these initiators or sodium peroxysulfite in a hydroperoxide described later, sodium ethylenediaminetetraacetate complex of ferrous ion, Redox initiators in combination with reducing agents such as ammonium sulfite, ascorbic acid and ferrous pyrophosphate are exemplified. Examples of the oil-soluble polymerization initiators include acetyl chloride, 3,5,5-trimethylhexanoyl parkioside, lauroyl peroxide, benzoyl peroxide, and diacylpoxide such as naphthoyl baroxide; Ketone peroxides such as tyl ketone peroxide; cumene hydroperoxide, p-cymene hydroperoxide, diisopropyl benzene hydroperoxide, t-butyl hydroperoxide, t-pentyl hydroperoxide, P-mensperoxide Hydroperoxides such as hydroperoxides; peroxyesters such as t-butylperoxybivalte; veroxydicarbonates such as diisopropyl veroxydicarbonate and getylhexylperoxydicarbonate; Ki Organic peroxides such as sulfonyl peroxides such as silsulfonyl peroxide; redox polymerization initiators combining these organic peroxides with reducing agents such as Rongalite; and 2,2′-azobis Isobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2,4-dimethyl) Azo compounds such as valeronitrile).

When the aqueous dispersion obtained by polymerization is spray-dried with a spray drier, the vinyl chloride resin fine particles accompanying the exhaust air are separated and removed independently of the vinyl chloride resin granules, so that the desired vinyl chloride resin spherical shape is obtained. Collect the granules. Hereinafter, the process of recovering spherical vinyl resin granules by spray drying will be described with reference to FIG.

The dispersion of the vinyl chloride polymer is supplied to the chamber 1 of the spray dryer by the pump 4 and spray-dried. The spray dryer may be a well-known spray dryer used for a vinyl chloride resin for paste.For example, the spray type may be any type such as a rotary disk type atomizer, a two-fluid nozzle type, and a pressurized nozzle type. May be. Drying air Can be collected from the atmosphere, and there is no particular need to adjust humidity.

In addition, the temperature and air volume of the inlet and outlet of the drying air introduced into the chamber 1 of the dryer by the blower 7 may be the same conditions as those usually used for drying the aqueous dispersion of the vinyl chloride polymer. The degree of drying is such that the moisture contained in the dried granules is 0.05 to 1.5% by weight, preferably 0.01 to 1.0% by weight.

For example, in the case of a spray type using a rotating disk atomizer, the supply of the vinyl chloride polymer aqueous dispersion should be adjusted so that the drying inlet temperature is 100 to 190 ° C and the outlet hot air temperature is 50 to 70 ° C. I just need. This drying usually gives a powder having an average particle size of 20 to 100 m.

The resin granules having a large particle diameter fall into the cone below the chamber 1 of the spray drier, and are guided by the blower 8 from the bottom of the chamber to the bag filter 3 or a cyclone (not shown) through the empty pipe A, Drops and is collected in the lower discharge pipe D. The fine resin particles accompanying the exhaust air from the spray dryer are guided to the bag filter 2 or a cyclone (not shown) via the exhaust pipe B, fall, and are collected in the lower exhaust pipe C. In the present invention, the resin granules having a large particle diameter recovered from the discharge pipe D and the resin fine particles recovered from the discharge pipe C are each independently produced without being combined.

In the present invention, the ratio of spherical granules having a repose angle of 30 to 38 degrees and a diameter of 20 or more in the total mass is 60% by weight or more, and Spherical granules having a particle size of 35 to 120 / m and a bulk density (looseness) of 0.59 to 0.65 gZc, preferably an undispersed particle ratio of 0.30% by weight or less are obtained. The bulk density (looseness) of the spherical granules collected from the discharge pipe D below the bag filter 3 is the same as that of the damper 5 provided in the exhaust pipe B while maintaining the internal pressure of the spray dryer constant. The opening can be adjusted by adjusting the opening of the damper 6 provided in the empty pipe A below the chamber of the spray dryer, and adjusting the air volume of the empty pipe A and the exhaust pipe B. For example, in order to increase the bulk density (looseness) of the vinyl chloride resin granules collected in the discharge pipe D, the bulk density (looseness) can be reduced by opening the damper 5 so that the air volume in the exhaust pipe B increases. PVC Make sure that more fine particles of NIR 榭 fat are collected on the exhaust pipe B side.

The bulk density of the vinyl chloride resin granules can also be adjusted by changing other operating conditions of the spray dryer. For example, in order to increase the bulk density (looseness) of the resin granules, in the case of a rotary disk type atomizer, the temperature of the inlet of hot air blown into the chamber of the spray dryer is increased, and an aqueous dispersion of a vinyl chloride polymer is used. For example, it is possible to adopt a method such as increasing the feed rate of the gas or reducing the rotation speed of the atomizer. In the case of a pressurized nozzle type, a method such as increasing the spray pressure can be adopted. By changing the operating conditions in the direction of increasing the diameter of the spray droplets, the bulk density (looseness) of the granules can be increased. However, conditions where the spray droplets are too large to fall without drying must be avoided.

In the spray drying step, as the resin fine particles that are separated and removed independently of the vinyl chloride resin granules, on the other hand, vinyl chloride resin granules having the above-mentioned desired properties can be collected from the lower part of the chamber of the spray dryer. The diameter and average particle diameter of the resin fine particles are not limited, but those having a diameter of about 50 xm or less and an average particle diameter of about 10 to 30 m are typical. The resin fine particles can be used in a different manner from the vinyl chloride resin granules of the present invention. For example, it can be used as it is or pulverized for thickening adjustment to be added to a low-viscosity first sol, or shipped to small-lot users.

The spray dryer used in the present invention has a repose angle of 30 to 38 when the vinyl chloride resin granules collected from the lower part of the chamber via baggage piping A through bagging pipe A or bag outlet pipe outlet. The ratio of spherical granules having a diameter of 20 m or more is 60% by weight or more, the average particle size is 35 to 200 m, and the bulk density (relaxing) power SO.59 to 0.65 g / It is sufficient that the granules have a structure that can be independently commercialized as granules having an undispersed particle ratio of preferably not more than 0.3% by weight. Device configuration other than the above-mentioned damper for the empty piping A and the damper for the exhaust piping B, such as the set position of the exhaust piping, the configuration of the piping from the piping to the resin fine particle collection device, and the configuration of the fine particle collection device There are no particular restrictions on.

As described above, in the present invention, fine resin particles accompanying exhaust air from a spray dryer are used. Are independently separated and removed to obtain vinyl chloride resin granules having the above-mentioned desired characteristics.

Conventionally, the resin granules having a large particle diameter recovered from the discharge pipe D and the fine resin particles recovered from the discharge pipe C were combined into a final product. Such conventional products have a smaller angle of repose, a smaller proportion of spherical granules having a diameter of 20 m or more, a smaller average particle size, and a lower bulk density than the resin granules of the present invention.

In addition, the above-mentioned conventional products have a large undispersed particle ratio and are inferior in plasticizer dispersibility compared to the resin granules of the present invention. This is because the fine resin particles (generally 5 to 15 m in diameter) that accompany the exhaust air circulate in the high-temperature chamber and stay for a long time, so that the particle surfaces are fused by heat and become hard, It is considered that when resin granules are merged with resin granules having a large diameter, hard resin fine particles are distributed on the surface of the granules to form a skin layer. In contrast, in the present invention, the particles in the spray droplets are well packed with each other, and only the resin granules having a high bulk density and a large particle diameter are collected independently of the above resin fine particles. That's why.

Hereinafter, Examples and Comparative Examples will be described in order to specifically explain the present invention. However, the present invention is not limited to these examples.

In the examples, the characteristics of the resin particles were evaluated by the following evaluation methods. Parts and percentages are by weight unless otherwise specified.

(1) Average particle size of granules: Measure the cumulative particle size distribution in a methanol solvent using a laser one-light diffraction particle sizer (Malvern Co., Ltd., Mass Spectrometer), and determine the average particle size equivalent to 50% by weight. Diameter (unit: m).

(2) Bulk density (loose): Measured according to JIS-SK7211, using a powder tester manufactured by Hosokawa Powder Engineering Laboratory Co., Ltd. Unit: gZc c.

(3) Bulk density: Measured with 180 seconds (60 cycles) of tapping using a powder tester manufactured by Hosokawa Powder Engineering Laboratory Co., Ltd. Unit: g / c c.

(4) Angle of repose: Measured using a powder tester manufactured by Hosokawa Powder Engineering Laboratory Co., Ltd. The smaller the angle of repose (degree), the better the powder flowability.

(5) Dispersion: Measured using powder tester Yuichi manufactured by Hosokawa Powder Engineering Laboratory Co., Ltd. Was. The larger the value of the degree of dispersion (%), the more dust is scattered.

(6) Floating time: Place 20 g of the sample powder and granules in a 100 cc glass stoppered sample tube, shake it in the axial direction (vertically) 10 times in 5 seconds at an amplitude of 20 cm, and let it stand still. The inside was observed, and the time (unit: seconds) until dust generation stopped was measured. The greater the amount of dust generated, the longer the flouring time.

(7) Compressibility: Calculated by the following formula. The larger the value of the degree of compression (%), the greater the blocking property.

Compressibility (%) = [bulk density (hard) One bulk density (loose)]

÷ Bulk density (loose) X 100

(8) Undispersed particle ratio: It is indicated by the remaining amount (%) on a 250 mesh sieve. 100 g of the sample powder and 60 g of octyl phthalate are placed in a cylindrical container having an inner diameter of 85 mm. In the center of the plane, a petal-shaped flat blade 12 with a blade length a of 35 mm from the rotation axis center, a horizontal blade width b of 20 mm, and a thickness c of 0.7 mm shown in Figs.2A and 2B is shown. An agitating blade 11 consisting of four cruciforms arranged in a fixed ring 9 (ring height d is 14 mm, outer dimension e is 13 mm) at the lower end of an agitating shaft 10 with a diameter of 8 mm 5 mm from the center. The plastisol obtained by stirring and mixing by rotating the stirring blade 11 at a rotation speed of 500 pm for 5 minutes is diluted with 100 g of mineral spirit, filtered through a JIS 62 standard sieve (250 mesh), and treated with methanol. Wash off on a Petri dish of known weight. Methanol is volatilized to obtain the weight on the dish, and the result is expressed as a percentage of 100 g of the sample powder. The smaller the value of the undispersed particles (%), the better the sol dispersibility.

Example 1

Seeding emulsion polymerization of vinyl chloride was carried out according to a conventional method, and 92 parts of a particle component having a mode particle size of 1.2 z / m and a mode particle size of 0.2; 100 parts of a vinyl chloride resin composed of 8% of a um particle component and 100 parts of sodium dodecylbenzenesulfonate A 46% solids aqueous dispersion containing 1.0 part of A rotary disk type atomizer (diameter 12 cm) (not shown) in the top of the spray dryer 1 having a chamber consisting of a cylindrical section and a conical section, and an insert attached to the cylindrical section to discharge exhaust air 8 OA exhaust pipe B, Under the chamber 1, a spray drier 1 with air carrying pipes A for collecting particles having a large particle size not entrained by the exhaust air is used.The inlet hot air temperature is 130 ° C, the outlet hot air temperature is 55 ° C, The aqueous dispersion was dried at 18,000 rpm of an atomizer.

The openings of the damper 5 of the exhaust pipe B and the damper 6 of the empty pipe A were opened 70% and 80%, respectively. The average particle size of salt vinyl resin granules obtained from sampling pipe D is 72 ^ m, bulk density (loose) «0.61 gZc c, angle of repose is 34 degrees, dispersity is 18.5%, undispersed particle rate is 16.4% there were.

Example 2

Using the same aqueous dispersion spray-drying apparatus as in Example 1, the same drying temperature conditions were used, and only the number of revolutions was reduced to 12000 rpm, and the same aqueous dispersion of biel chloride resin was dried. The opening of damper 6 for pipe 5 and pipe A was 70% open and 80% open, respectively. The average particle size of the resin granules obtained from sampling pipe D was 85, the bulk density (loose) was 0.63 g / cc, the angle of repose was 33 degrees, the dispersity was 20.3%, and the undispersed particle ratio was 0.19%. Was.

Comparative Example 1

The vinyl chloride aqueous resin dispersion was dried in the same manner as in Example 1. However, the average particle size of the vinyl chloride resin granules collected by Bagfill 1 and obtained from the collection pipe C was 32 m, The density (loose) was 0.41 gZc c, the angle of repose was 42 degrees, the dispersity was 55.6%, and the undispersed particle ratio was 0.53%.

Comparative Example 2

The vinyl chloride resin aqueous dispersion was dried in the same manner as in Example 2. However, the average particle size of the vinyl chloride resin granules collected at Bagfill 1 and obtained from the collection pipe C was 36 m, and the bulk density ( The looseness was 0.46 g / cc, the angle of repose was 46 degrees, the dispersity was 48.5%, and the undispersed particle ratio was 0.62%.

Comparative Example 3

The whole amount of the granules collected in the collection pipes C and D of Example 1 and Comparative Example 1 was mixed, and the average particle diameter was 40 m, the bulk density (loose) was 0.48 g / cc, and the angle of repose was 43 degrees. A vinyl chloride resin granule having a dispersity of 50.4% and an undispersed particle ratio of 0.44% was obtained. Comparative Example 4

The whole amount of the granules collected in the collection pipes C and D of Example 2 and Comparative Example 2 was mixed, and the average particle diameter was 45 m, the bulk density (loose) O. S gZc c The angle of repose was 43 degrees, the degree of dispersion was 31.5%, A vinyl chloride resin granule having an undispersed particle ratio of 0.53% was obtained. Comparative Example 5

The drying conditions were as follows: Humidity 0.01 kg water Zkg air air, hot air inlet temperature 80 ° C, outlet hot air temperature 45, and the damper 5 for pipe B and damper 6 for pipe A were opened 90% and 60, respectively. The aqueous dispersion of the salted vinyl resin was spray-dried in the same manner as in Example 1 except that it was opened at%, and the whole amount of the granules collected by the collection pipes C and D was mixed. The obtained vinyl chloride resin granules have an average particle size of 45 m and bulk density.

(Loose) 0.55 g / cc, angle of repose 34 degrees, dispersity 40.2%, undispersed particle ratio 0.35%.

Table 1 summarizes the results obtained in Examples 1 and 2 and Comparative Examples 1 to 5.

Example Comparison example

1 2 1 2 3 4 5 One revolution of atomizer (rpm) 18000 12000 18000 12000 18000 12000 12000 Collection piping * ¹ 3 3 2 2 2 + 3 2 + 3 2 + 3 Water content of granules (%) 0.25 0.28 0.28 0.31 0.27 0.29 0.40 Average particle size (; m) 72 85 32 36 40 45 45 20 im or more of particles 97 98 75 78 84 85 82 Ratio (%) 40 or more 85 90 35 37 55 60 59 Bulk density (loose) (gZcc) 0.61 0.63 0.41 0.46 0.48 0.49 0.55 Bulk density (hard) (gZcc) 0.71 0.69 0.72 0.68 0.69 0.67 0.71 Angle of repose (degrees) 34 33 42 46 43 43 34 Dispersion (%) 18.5 20.3 55.6 48.5 50.4 31.5 40.2 Powder Dance time (sec) 0.3 0.2 2.0 3.5 1.3 1.2 1.8 Compression (%) 16.4 9.5 75.6 47.8 43.8 36.7 29.1 Undispersed particle ratio (%) 0.15 0.19 0.53 0.62 0.44 0.53 0.35

* 1 Granule collection pipe shown in Fig. 1; (2 + 3) is a mixture of granules collected from pipes 2 and 3.

As shown in Table 1, according to the present invention, an aqueous dispersion of a vinyl chloride resin obtained by emulsion polymerization or fine suspension polymerization is spray-dried, and if necessary, the opening degree of the damper of the exhaust pipe and the damper of the empty granule pipe is adjusted. The vinyl chloride resin granules collected from the lower part of the dryer chamber and captured by the bag filter 3 via the air carrying pipe A and collected are granules with a repose angle of 30 to 38 degrees and a diameter of 20 m or more. Of 60% by weight or more, average particle size of 35 to 120 rn, and bulk density (loose) of 0.59 to 0.65 gZc c, more preferably 0.33% by weight or less of undispersed particle ratio, powder fluidity In addition to the good dispersion, the dispersion time is very short. Therefore, the powder has extremely low dusting properties and excellent sol dispersibility (Examples 1 and 2).

The fine particles accompanying the exhaust air discharged from the pipe B installed in the middle part of the dryer chamber are collected by the bag filter 12 and the particles with a repose angle of 42 and 46 degrees and a diameter of 20 η or more are collected. 75% and 78% by weight, average particle size 32 m and 36 m, bulk density (loose) 0.41 g / cc and 0.46 g, cc, undispersed particle ratio 0.53% by weight and 0.62% by weight, powder The fluidity is extremely poor, the degree of dispersion is extremely large, the dusting time is very long due to the long flouring time, and the sol dispersibility is poor (Comparative Examples 1 and 2). The granules collected in the lower piping A of the dryer chamber and the fine powder in the exhaust air from the piping B in the middle part of the chamber are obtained by the conventional method of spraying and drying the powdered polyvinyl chloride for paste processing. The characteristics of the powders obtained by mixing with the following are also: angle of repose 43 degrees, ratio of granules with a diameter of 20 m or more 84% by weight and 85% by weight, average particle size 40 μιη and 45 m, and bulk density (loose) 0.488 / 0.49 g / cc, undispersed particle ratio 0.44% by weight and 0.53% by weight. Poor powder flowability, high degree of dispersion, and considerably long dusting time. It is found that the sol dispersibility is large and the sol dispersibility is poor (Comparative Examples 3 and 4). In addition, the opening degree of dampers 5 and 6 is adjusted within the range of the general manufacturing method of resin granules by a conventional spray dryer, and the bulk density of the integrated granules collected in piping C and piping D is increased. The results of Comparative Example 5 thus obtained were as follows: the angle of repose was 34 degrees, the ratio of granules having a diameter of 20 zzm or more was 82% by weight, the average particle size was 45, and the bulk density (loose) was 0.55 g. cc, the undispersed particle ratio is 0.35% by weight, the powder fluidity and the sol dispersibility are inferior to those of the present invention. This was not much different from the case of spray drying of the vinyl chloride resin for single-stroke processing (Comparative Examples 3 and 4). Industrial applicability

The vinyl chloride resin granules of the present invention have a smaller angle of repose, a larger proportion of spherical granules having a diameter of 20 / m or more, and a larger average particle size, as compared with vinyl chloride resin granules prepared by a conventional method. The bulk density (looseness) is large, and preferably, the undispersed particle ratio is small. Therefore, the vinyl chloride resin granules of the present invention have good flow properties, low dusting properties, good blocking properties, and preferably excellent plasticizer dispersibility.

Therefore, the vinyl chloride resin granules of the present invention are excellent particularly for paste processing.

Claims

The scope of the claims

1. Spherical granules that are aggregates of primary particles of vinyl chloride resin, the angle of repose of which is 30 to 38 degrees, the ratio of spherical granules with a diameter of 20 z / m or more is 60% by weight or more, and the average particle size is 35 A polyvinyl chloride resin granule for paste processing, characterized by a bulk density of up to 200 m and a bulk density (looseness) of 0.59 to 0.65 g Ze e.

2. The vinyl chloride resin composition for paste processing according to claim 1, further comprising an undispersed particle ratio of 0.30% by weight or less.

3. An aqueous dispersion of a vinyl chloride polymer obtained by emulsion polymerization or fine suspension polymerization of vinyl chloride or a monomer mixture mainly composed of vinyl chloride in the presence of a surfactant is spray-dried to give vinyl chloride resin granules. In the method for producing vinyl chloride resin granules for recovering the spheres, when the aqueous dispersion is spray-dried, the vinyl chloride resin fine particles accompanying the exhaust air are separated and removed independently of the vinyl chloride resin granules, whereby Of spherical granules having a repose angle of 30 to 38 degrees, a diameter of 20 zm or more, 60% by weight or more, an average particle diameter of 35 to 200 / xm, and a bulk density (loose) of 0.59 to A method for producing vinyl chloride resin granules for paste processing, comprising recovering 0.65 gZc c of vinyl chloride resin granules.

4. By adjusting the degree of opening of the damper provided in the exhaust pipe and the damper provided in the empty pipe under the chamber of the spray dryer, the fine particles accompanying the exhaust are independent of the vinyl chloride resin granules. 4. The method for producing vinyl chloride resin granules for paste processing according to claim 3, wherein the particles are separated and removed.