JPH0511131B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing a granular polyvinyl chloride paste resin having both excellent powder properties and sol properties. [Prior Art] Polyvinyl chloride paste resin (hereinafter abbreviated as paste PVC) is usually used in the form of a plastisol dispersed in a plasticizer or an organosol in which an organic solvent is added to the plastisol. If coarse particles are present in plastisol or organosol,
During settling or coating processing,
Since there are problems such as streaking and scratches on the surface, it is essential that the paste PVC particles be mixed with a plasticizer and dispersed quickly. For this reason, currently commercially available paste PVC is provided in the form of fine powder with an average particle size of 10 μm or less. As a result, many problems have arisen, such as poor powder fluidity, low bulk specific gravity, and scattering of fine powder. Poor powder fluidity causes trouble when filling or taking out packaging bags, and also hinders automation of weighing. A low bulk specific gravity requires packaging bags with a large capacity and increases costs for storage and transportation. Further, scattering of fine powder causes product loss and health and safety problems. [Problems to be Solved by the Invention] One way to solve these problems is to form fine powder paste PVC into particles.
In order to improve powder properties such as fluidity, bulk specific gravity, and scattering properties, which are disadvantages of paste PVC, by increasing the particle size of the granulated paste PVC and increasing the cohesive force between the particles. It is desirable to use particles that are difficult to disintegrate due to external force and have a high density.
However, the larger the particle size and the larger the cohesive force between particles, the lower the dispersibility when mixed with a plasticizer, making it difficult to satisfy the sol physical properties required for paste processing. As described above, the powder properties required for powder handling and the sol physical properties required for paste processing are contradictory properties, and it is extremely difficult to produce paste PVC that has both properties. Today, granulation of fine powders to improve powder properties is performed on many powders. However, the powder currently being granulated is used for pharmaceuticals, agricultural chemicals,
They are used in detergents, catalysts, etc., either dissolved in water or as they are, and there are almost no known examples of them being used after being reconstituted into fine powder.
Regarding granulation of paste PVC, the obtained granules must be quickly dispersed into fine particles when mixed with a plasticizer, and conventional granulation methods cannot be applied as is. Granulation methods include rolling granulation, compression granulation,
Fluidized bed granulation method, extrusion granulation method, etc. are known. The present inventors have also conducted research on these methods, but have not been able to find a granulation method that fully satisfies both powder properties and sol physical properties. In addition, although granulation is possible with either method, paste
Due to the poor fluidity of PVC, it was difficult to supply it or to make it uniform within the system, making it difficult to operate. The inventors of the present invention have intensively studied methods for producing granular paste PVC that has both excellent powder properties and sol properties, and as a result, they have discovered that the object can be achieved by the following method and have arrived at the present invention. [Means for Solving the Problems] That is, the present invention is directed to the production of a granulated polyvinyl chloride paste range, characterized in that a liquid binder is added when spray drying a polyvinyl chloride paste latex. It's in the method. The paste PVC latex used in the present invention may be manufactured by emulsion polymerization, microsuspension polymerization, or other polymerization method used for manufacturing paste PVC, and is mainly made of vinyl chloride homopolymer or vinyl chloride. Any copolymer with vinyl acetate or the like as a component may be used. Spray drying is a drying method in which latex is atomized using a centrifugal rotary atomizer and instantaneously dried by contact with hot air to obtain a powder product. Granular paste PVC is obtained by spray drying method without any grinding process. The spray drying apparatus may be a pressurized nozzle type, a two-fluid type, or a rotating disk type. The drying temperature is preferably 100°C to 150°C in terms of hot air inlet temperature. The hot air outlet temperature is preferably 50°C to 70°C. If the drying temperature is high, paste PVC can have excellent powder properties, but the dispersibility during solization will decrease, which is undesirable. In addition, if the drying temperature is low, dew condensation occurs in the drying chamber, and sufficient drying is not possible, which adversely affects the physical properties of the product, which is undesirable. The liquid binder used in the present invention includes polyhydric alcohols and/or ether compounds of polyhydric alcohols, such as glycols such as ethylene glycol and propylene glycol, ethylene glycol dibenzyl ether, ethylene glycol dibutyl ether, and ethylene glycol. Glycol diether compounds such as glycol diethyl ether and ethylene glycol dimethyl ether,
Examples include glycol monoether compounds such as ethylene glycol monobenzyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, and butyl acetate cellosolve. These liquid binders are used singly or in a mixture of 1 to 5 parts by weight per 100 parts by weight of the solid content of the paste PVC latex. If the amount of liquid binder is less than 1 part by weight per 100 parts by weight of the solid content of the paste PVC latex, the addition effect will not appear and the sol dispersibility will be poor; Addition of a binder reduces stability and adversely affects the physical properties of the sol. Liquid binder is paste
A method in which a liquid binder is added directly to PVC latex and spray-dried, a method in which a liquid binder is slightly acidified in an aqueous medium and then added to a paste PVC latex, a paste
There are no particular restrictions on the addition method, such as a method of spraying the liquid binder at the same time as spray drying the PVC latex. [Effects of the Invention] The paste PVC dried in this manner has an average particle diameter of about 30 μm, a sharp particle size distribution, and a product that satisfies both powder characteristics and sol physical properties can be obtained. Furthermore, the spray drying in the present invention is a common process for drying latex, and since it does not require a pulverization process, it is also useful in terms of cost reduction. [Examples] The present invention will be explained in more detail by Examples below, but the present invention is not limited to these Examples. Prior to the examples of the invention, the manufacturing method of latex used in the examples and comparative examples will be shown. Reference Example 1 Method for producing latex A Production of seed material 1 in micro suspension system Mix the following. Vinyl chloride 40Kg Lauroyl peroxide 0.6Kg 10% by weight aqueous solution of sodium dodecylbenzenesulfonate Water required to bring the vinyl chloride concentration to 43% by weight 4Kg The mixture was homogenized to a microsuspension, which was then dispersed into a microsuspension of 120% by weight. Enter the autoclave. Heat to 52°C under autogenous pressure. When the pressure drops, polymerization is stopped and unreacted vinyl chloride is degassed. A latex with a polyvinyl chloride concentration of 40% by weight was obtained,
The particles have an average particle size of 0.4 μm and contain 1.5% by weight of lauroyl peroxide with respect to the polymer. Production of seed material 2 using an emulsion system Place the following items into a 120 autoclave. Water 60.6 Kg 10% by weight aqueous solution of sodium tetradecyl sulfonate 2.6 Kg Ammonia 0.053 Kg Vinyl chloride 52 Kg The mixture is heated to 52° C. under autogenous pressure and this temperature is maintained during the operation. As soon as the mixture reaches 52° C., 0.035 Kg of potassium persulfate is introduced. 15
After min, 10% of sodium tetradecyl sulfonate
Add 4.75 of the aqueous solution continuously at a rate of 0.5 Kg/hr. After 9 hours and 30 minutes at 52°C, unreacted vinyl chloride is degassed. The resulting latex has a polymer concentration of 40.2% by weight and an average particle size of 0.12 μm. These particles do not contain initiator. Polymerization Put the following into a 120 autoclave. Water 33.2Kg 5.7Kg Latex 1 i.e. lauroyl peroxide
2.3 Kg of polyvinyl chloride containing 34.5 g 3.5 Kg of latex 2, i.e. 1.4 Kg of polyvinyl chloride 1.5 Kg of a 10% by weight aqueous solution of sodium dodecylbenzenesulfonate 55 Kg of vinyl chloride The mixture was stirred in a stirrer at 50 revolutions/min and 52 Heat to ℃. After 3 hours, 2.5 kg of 10% by weight aqueous solution of sodium dodecylbenzenesulfonate
Add. A pressure drop is observed after 18 hours of reaction. When the pressure drops to 2 pars, unreacted vinyl chloride is degassed. A latex with a polymer concentration of 54% by weight and a viscosity of 38 cp is obtained. The particle size distribution of the obtained latex shows that this polymer has an average particle size of 0.20μm and 0.98μm.
It was shown that it consists of two populations of particles with m. An increase in particle size was observed for Latex 2, which does not contain initiator. The granules account for 29% by weight of the polymer. Reference example 2 Manufacturing method for latex B
Kg of water, produced by micro suspension polymerization and
6 Kg of seed material with a concentration of 33.3% by weight, i.e. 2 Kg of polyvinyl chloride containing 30 g of lauroyl peroxide and having an average particle size of 0.4 μm, 0.3 Kg of sodium dodecylbenzenesulfonate, 2.5 g of copper sulfate and 50Kg of vinyl chloride was introduced. The mixture was heated at 52° C. under natural pressure and this temperature was maintained during the reaction. As soon as the mixture reached 52° C., the introduction of a 4 g/aqueous solution of ascorbic acid was started. acid 0.33
g/hr for 3 hours, then 0.22 g/hr for 3 hours, then 0.1 g/hr until the reaction was complete. After 9 hours, a pressure drop was observed, which is characteristic of the end of the reaction. The introduction of ascorbic acid was stopped and unreacted monomer was degassed. Having a concentration of 42.2% by weight, i.e. 89.7% by weight of the vinyl chloride used
111 Kg of polymer dispersion was obtained with an actual conversion of . The average particle size of the obtained latex was 1.1 μm. Examples 1 and 2, Comparative Examples 1 to 3 Paste PVC latex A (solid content concentration 40%)
2 was added with ethylene glycol as a liquid binder in the amount shown in Table 1, and spray-dried with stirring. The spray dryer used was a laboratory spray dryer model R2 manufactured by Sakamoto Giken. The drying inlet temperature was set at 130°C and the drying outlet temperature was set at 60°C. Table 1 shows the powder properties and sol properties of the obtained granular paste PVC.

[Table] Comparing the values without the addition of enlene glycol with commercially available products, the powder properties have been significantly improved, with values that have excellent fluidity comparable to general-purpose PVC and ease of handling as a powder. However, this is because the primary particles agglomerate because they are not pulverized, resulting in an apparent increase in particle size. If ethylene glycol is not added, a plasticizer is added and it is difficult to loosen even when kneaded with a mixer and has poor dispersibility. In contrast,
When ethylene glycol was added and spray-dried, as shown in the examples, the powder properties were excellent and the dispersibility in the plasticizer was also good. However, as the amount of ethylene glycol added increased, it became difficult to loosen the sol, and the physical properties of the sol deteriorated. Examples 3 and 4, Comparative Examples 4 to 7 Spray drying was carried out in the same manner as in Example 2, except that the liquid binder shown in Table 2 was used instead of ethylene glycol. Table 2 shows the results regarding the type of liquid binder.

[Table] Often used as a plasticizer for paste PVC
DOP (di-2-ethylhexylphthalic acid) and other liquid paraffin higher alcohols have poor sol properties. Moreover, it did not become a sol with polyvinyl alcohol. Examples 5 to 7, Comparative Example 8 Drying was performed in the same manner as in Example 2, except that the spray drying temperature was changed. The results are shown in Table 3.

[Table] The lower the drying temperature, the better; if the drying temperature is high, it will be susceptible to thermal history, fusion between primary particles will occur, it will be difficult to unravel even when a plasticizer is added, and the dispersibility will be poor. From these examples, the inlet temperature is 100 to 150℃, and the outlet temperature is 50 to 70℃.
It can be seen that the paste PVC dried at 100 mL exhibits excellent powder properties and sol physical properties. These granulated paste PVCs had good moldability and physical properties of molded products. Example 8 Latex A as paste PVC latex
Drying was carried out in the same manner as in Example 2 except that latex B was used instead. The results are shown in Table 4.

[Table] Latex B obtained by polymerization from 1 seed was spray-dried with the addition of ethylene glycol.
Similar to Latex A, a granulated product with excellent powder properties and sol properties was obtained. From the above results, when spray drying paste PVC latex, by adding a liquid binder, it is possible to gently aggregate the primary particles and improve their dispersibility in the plasticizer. It is clear that this is industrially advantageous because paste PVC, which is conventionally a fine powder and difficult to handle, can be granulated using the usual means of spray drying.

Claims (1)

[Scope of Claims] 1. A method for producing granulated polyvinyl chloride paste resin, which comprises adding glycol and/or an ether compound of glycol when spray-drying polyvinyl chloride paste latex. 2. The manufacturing method according to claim 1, wherein 1 to 5 parts by weight of glycol and/or a glycol ether compound is added to 100 parts by weight of the solid content of the polyvinyl chloride paste latex.