JPH05194754A - Production of granular resin - Google Patents

Abstract

PURPOSE:To obtain a granular vinyl chloride resin which is less apt to cause dusting during paste sol preparation, shows good powder flowability, can be automatically metered, and can be easily dispersed into a plasticizer to give a low-viscosity paste sol having good flowability even under high shearing. CONSTITUTION:A poly(vinyl chloride) latex obtained by emulsion polymerization or fine suspension polymerization is mixed with a vinyl chloride resin powder for paste use. This mixture is then spray-dried to thereby produce a granular resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a granular resin which has little powdering and has excellent powder fluidity and which can be used as a resin for paste processing.

[0002]

2. Description of the Related Art In recent years, attempts have been made to make a vinyl chloride resin for paste itself, which is a fine powder, into a granular form for the purpose of preventing dusting of the vinyl chloride resin for paste and automatically measuring it. For example, JP-A-2-133409 and JP-A-2-13409
No. 3410 discloses that an aqueous dispersion of a vinyl chloride resin for paste processing is dried using a spray dryer having a rotary disk type atomizer, and the number of rotations of the rotary disk and the temperature and humidity of dry air are measured during drying. The granule resin is manufactured under controlled conditions. However, usually in this method, if the rotation speed of the rotating disk is reduced to increase the particle size of the granules, drying at high temperature is required, and the resulting granule resin becomes hard and does not easily disperse in the plasticizer. No sol is formed.

On the other hand, when the drying temperature is lowered, the drying becomes insufficient, and there is a drawback that another drying step is required again or a larger spray drying device must be installed, which is economically disadvantageous. I can't. Further, even when an aqueous dispersion containing only fine particles is dried to produce a vinyl chloride resin for paste processing as in the conventional technique, the paste sol prepared from the resin has a high viscosity. Or, the stability of viscosity with time becomes poor. Also,
A method for producing a granular vinyl chloride resin, in which a liquid coagulant is added to what is once made into a vinyl chloride resin for processing a fine powder paste, the mixture is granulated through an extruder, and the obtained granulated product is dried with a fluid dryer, It is disclosed in Japanese Patent Publication No. 48-23180.

This method requires a new drying step, and since the granular vinyl chloride resin produced solidifies only the vinyl chloride resin fine particles, it cannot be used for paste processing depending on the drying temperature, and is temporarily plasticized. Even if the agents are mixed to form a paste sol, its fluidity is not always good, and there is a problem in stability over time.
Further, although a resin which is made into a granular form using an organic liquid or an aggregating agent is known, there is a concern that various properties of the resin itself of the organic liquid or the aggregating agent such as durability and printability may be adversely affected. It is difficult to use paste sol prepared from these resins for high speed coating, rotary screen printing, spray coating, dipping, etc., and it is necessary to adjust viscosity, fluidity, etc. by mixing with other resins. Met.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have found that powder generation is low, powder flowability is excellent, automatic metering is possible, and it melts more than a vinyl chloride resin produced by a suspension polymerization method. As a result of earnest studies to obtain a vinyl chloride resin that is easy to obtain, and has a low viscosity when dispersed in a plasticizer, and a paste sol that has good fluidity even in a high shear region, a result of emulsion polymerization or fine suspension A part of an aqueous dispersion containing fine vinyl chloride resin particles of usually 3 μm or less produced by the turbid polymerization method is spray-dried, and the surface of the fine vinyl chloride resin particles obtained by drying is fused to several 10 μm. The particles as they are or pulverized and mixed with the original aqueous dispersion, after increasing the solid content concentration of the aqueous dispersion, by spray-drying again in the usual manner, a granular form that can achieve the above objects. Vinyl chloride The inventors have found that a resin can be obtained and completed the present invention.

That is, the object of the present invention is to prevent powdering, to have good powder fluidity, to enable automatic weighing, and to melt more easily than a vinyl chloride resin produced by the suspension polymerization method,
Another object of the present invention is to provide a method for producing a granular resin, which can easily give a paste sol having a low viscosity when dispersed in a plasticizer and exhibiting good fluidity in a high shear region.

[0007]

However, the gist of the present invention is that the polyvinyl chloride latex (A) obtained by the emulsion polymerization method or the fine suspension polymerization method and the vinyl chloride resin powder for paste ( A method for producing a granular resin, which comprises spray-drying after mixing with B).
To explain the present invention in detail, the polyvinyl chloride latex (A) comprises fine vinyl chloride polymer particles having a particle size of 3 μm or less, usually 0.1 to 2 μm, produced by an emulsion polymerization method or a fine suspension polymerization method. It is an aqueous dispersion containing.

The emulsion polymerization method is, for example, vinyl chloride or a comonomer copolymerizable therewith, specifically vinyl acetate,
A method of polymerizing a mixture of alkyl (meth) acrylate, ethylene, propylene, etc. in the presence of an emulsifier for polymerization such as sodium lauryl sulfate, sodium dodecylbenzene sulfonate, etc. and a water-soluble polymerization catalyst. The legal method is to stabilize, for example, by finely dispersing a mixture of vinyl chloride or a comonomer copolymerizable therewith together with an emulsifying agent or a suspending agent and a vinyl chloride-soluble polymerization catalyst in a homogenizer or the like in a disperser such as a homogenizer. After that, it is a method of polymerizing. In the polyvinyl chloride latex (A) produced by these methods, most of the vinyl chloride polymer contained therein is fine particles having a size of 3 μ or less, but coarse particles which do not disintegrate only by stirring during the polymerization process may be produced. Therefore, in the method of the present invention, it is desirable to remove coarse particles of 500 μm or more, preferably particles larger than 65 μm before use.

Vinyl chloride resin powder for paste (B)
What is usually manufactured is obtained by spray-drying the above-mentioned polyvinyl chloride latex obtained by emulsion polymerization method or fine suspension polymerization method. By spray-drying a latex containing vinyl chloride polymer fine particles having a particle size of 3 μm or less, particles having a size of about 10 μm or more in which the surfaces of fine particles are fused to each other are generated, and for example, a spray mechanism such as a rotating disk, a pressure nozzle, or a two-fluid nozzle. Spherical particles of various sizes can be obtained according to various conditions such as the number of revolutions, pressure, and the flow rate of latex given to. Further, when the drying temperature is increased, for example, when the exhaust air temperature of the drying device, that is, the outlet temperature of the drying device is set to 65 ° C. or higher, the fusion force between the fine particles is strong, and the obtained particles are stirred and dispersed in the plasticizer. Particles do not collapse. Exhaust air temperature 5
0 to 60 ℃ range, especially by adjusting to 55 ℃ 1
0-40% disintegrates into fine particles.

On the other hand, if the particles are dried at a temperature of 50 ° C. or lower, the particles disintegrate in the plasticizer and most of them return to fine particles. In the method of the present invention, it is desirable to use, as the vinyl chloride resin powder for paste (B), one having the same chemical composition as the vinyl chloride polymer fine particles contained in the latex (A). And the like may have different compositions. As the vinyl chloride resin powder (B) for paste, usually, vinyl chloride or a mixture thereof with a comonomer copolymerizable therewith is added in the presence of a suspending agent and, in some cases, an emulsifier and a vinyl chloride-soluble polymerization catalyst. A so-called paste-mixing resin obtained by polymerization can also be used. The resin is a single 5-10
It is a spherical resin having a particle size of about 0 μ, and the average particle size is usually in the range of 20 to 40 μ.

When the granular resin produced by the method of the present invention is used for paste processing, it is preferable to use a vinyl chloride resin powder (B) for paste having a particle size larger than 150 μ after classifying it. In order to ensure good fluidity in the high shear region of the sol, the average particle size is 5 to 45 μm.
It is desirable to use the one within the range. Of course, if the vinyl chloride resin powder for paste (B) has a large particle size, it may be crushed by a crusher and classified into a size range for use. When the granular resin is used for producing an extremely thin film, for producing a transparent film, or for fine line drawing screen printing, the powder (B) is used.
It is preferable to use particles having a particle size of less than 5μ.

The method of the present invention comprises the above-mentioned polyvinyl chloride latex (A) and vinyl chloride resin powder (B) for paste.
And are mixed uniformly to form a slurry or latex having an increased solid content of latex (A), and then spray-dried. The solid content concentration of the slurry or latex after blending the vinyl chloride resin powder (B) for paste is 50 to
It is preferably in the range of 75% by weight, and the compounding amount of the powder (B) is appropriately adjusted depending on the solid content concentration in the latex (A) after emulsion polymerization or fine suspension polymerization. The higher the solid content concentration of the latex (A), the better, and it is desirable to add the powder (B) after concentrating it by a method such as ultrafiltration.

By doing so, the amount of powder (B) added can be reduced, and the drying energy in the process of producing powder (B) can be reduced, which is economical. The amount of the powder (B) added to the latex (A) is in the range of 10 to 90% by weight, preferably 30 to 80% by weight of the dried granular resin, which is desirable from the viewpoint of the fluidity of the paste sol. . The mixture of latex (A) and powder (B) is
Although any method may be used, it is easy to form the uniform slurry or latex by successively adding the powder (B) while stirring the latex (A), and it is preferable in terms of solid content control.

A spraying mechanism for spray-drying the slurry or latex after increasing the solid content concentration is a rotating disk,
Various mechanisms such as a pressure nozzle and a two-fluid nozzle can be adopted, and a granular resin having various particle sizes can be obtained by selecting a spraying mechanism and spraying conditions. The particle size of the granular resin is 50-30
The range of 0 μ is preferable in terms of powder fluidity, strength of granules, dispersibility in a plasticizer, application and the like. Of course, it is desirable that the granular resin obtained by spray drying is used after being classified into various particle sizes, if necessary. The temperature of spray drying is
It is preferable that the temperature of the exhaust air at the outlet of the dryer is 55 ° C. or lower. When it is a paste sol at a drying temperature of 55 ° C. or higher, the dispersibility in a plasticizer is poor.

[0015]

EXAMPLES Next, the method of the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples unless it exceeds the gist. The latex (A), powder (B) and granular resin were evaluated as follows.

1 Measurement of particle size a) Particle size in latex Centrifugal sedimentation type particle size measuring machine CPSM (TECHNIDYN)
B) Particle size of dried product Laser diffraction type particle size measuring device (LA-50 manufactured by Horiba Ltd.)
Measurement using 0) c) Particle size of granular resin Same as in b) above. However, if the particle size exceeds 200μ, use a Tyler sieve. 2 Particle shape Scanning electron microscope (SEM) observation

3 Crush strength Using a micro compression testing machine (manufactured by Shimadzu Corporation, MCTM-500), one agglomerated particle of vinyl chloride resin is slowly applied with a load to be compressed, and a load value causing a rapid change is determined. A sudden load change reveals particle crushing. The crush strength was shown by the average load value (g / mm ² ) per particle cross-sectional area of 10 particles. 4 Powder flowability The angle of repose was measured using a powder tester (manufactured by Hosokawa Powder Research Institute). 5 Powder standing property 100 g of granular resin was dropped at one time from the top of a graduated cylinder with a height of 1 m, and the height of powder smoke immediately after the drop was evaluated. ◎: Dust and smoke 0 cm ○: Dust and smoke less than 50 cm △: Dust and smoke 50-100 cm ×: Dust and smoke over 100 cm

6 Viscosity of plastisol (a) Initial viscosity: vinyl chloride resin / plasticizer = 100/6
0 (part by weight) with a planetary mixer (N-50 type)
1 speed (61 rpm) x 5 minutes and # 2 speed (125
rpm) × 15 minutes mixing plastisol Brookfield type viscometer (B type viscometer) at 23 rpm at 50 rpm
Numbers in. (B) Viscosity with time: Numerical value obtained by similarly measuring (a) after holding the sol at 23 ° C. for 24 hours. (C) Viscosity at high shear: 100 with a Seaverse type viscometer (S type viscometer) under pressure of 90 psi of the above sol.
Outflow of plastisol per second (unit: g).

Examples 1 to 8 and Comparative Examples 1 to 3 (1) Production of polyvinyl chloride latex (A) (A-1) Latex: 100 kg of ion-exchanged water and lauroyl in a prepolymerization tank having a volume of 200 l equipped with a stirrer. 60 g of peroxide, 400 g of sodium lauryl sulphate, 200 g of lauryl alcohol were added, and after degassing the inside of the prepolymerization tank, 60 kg of vinyl chloride monomer was added,
The temperature was maintained at 35 ° C with stirring. Then after stirring uniformly,
Using a disperser (homogenizer), the desired droplet diameter (about 0.
It was dispersed in a polymerization tank having a volume of 200 l equipped with a stirrer that had been degassed in advance. After the transfer of the dispersion liquid was completed, the temperature of the polymerization reaction liquid was raised to 50 ° C. and fine suspension polymerization was carried out by a known method to obtain a latex containing vinyl chloride seed polymer particles having an average particle diameter of 0.6 μm.

Using the latex containing the seed polymer particles, polyvinyl chloride latex (A-1) was prepared as follows.
Was prepared. That is, 80 kg of deionized water and 5 kg of the seed polymer particles are placed in a 200 l polymerization tank equipped with a stirrer.
(Solid content in latex), after charging 20 g of sodium hydrogen carbonate, deaeration and vinyl chloride monomer 75 kg
Was charged, the temperature was raised to 55 ° C., and the solution was dissolved in advance and a 0.3% aqueous solution of sodium hydrogen sulfite was added little by little (about 1500 ml / hr) to the polymerization tank for 40 minutes continuously to carry out polymerization. Let it start. After the start of the addition of sodium hydrogen sulfite, the addition rate was adjusted so that the reaction was performed at a constant reaction rate.

Further, from the time when the polymerization rate reaches 10% to the end of the polymerization, sodium lauryl sulfate as an emulsifier is continuously prepared as an aqueous solution of about 8% at a rate of 0.1% per hour with respect to the vinyl chloride monomer. Was added. The total amount of emulsifier added was 0.6% based on the vinyl chloride monomer. When the polymerization pressure dropped 1 kg / cm ² from the vinyl chloride saturation pressure at 55 ° C., sodium sulfite was added to terminate the polymerization, and unreacted monomers were recovered. A 100-mesh wire mesh was used to remove coarse particles generated during the polymerization, but no coarse particles were found. The average particle size of the polymer particles in the obtained latex was 1.1 μ, and the solid content concentration of the latex was 41.0% by weight. The latex was adjusted to a solid content concentration of 45% by ultrafiltration.

(A-2) Latex: 90 kg of deionized water having a temperature of 54 ° C., 10 kg of potassium persulfate and 50 g of sodium pyrosulfite were placed in a polymerization tank equipped with a stirrer and stirred for about 20 minutes. Dissolved. Next, the pressure in the polymerization tank was reduced to -610 mmHg, and the pressure was reduced to 5 minutes
Hold at 5 ° C.

Next, 60 kg of vinyl chloride monomer was charged into the polymerization tank, and the temperature inside the tank was maintained at 50 ° C. 15 minutes after the monomer was charged, 0.2% that had been dissolved in advance
The potassium persulfate aqueous solution was gradually added at a rate of about 10 ml / min, and the reaction was continued while controlling the addition rate of the potassium persulfate aqueous solution so that a constant polymerization rate was maintained thereafter, after which the polymerization rate reached about 15%. At that time, another dissolved and about 8% aqueous solution of sodium lauryl sulfate was added, and the aqueous solution was added at a rate of about 80 ml / 10 minutes until the total amount of sodium lauryl sulfate added reached 360 g. The reaction was stopped when the pressure in the tank dropped 2.0 kg / cm ² from the saturation pressure of the vinyl chloride monomer at 50 ° C., and the unreacted monomer was recovered to obtain a polymer latex. The obtained latex was a monodisperse particle having a particle size of about 0.5 μ, and the stability of the latex was good.

Next, 4.5 kg (as solid content) of the obtained latex as seed latex and 80 kg of deionized water were charged in a polymerization tank having a volume of 200 l equipped with a stirrer, and then deaerated. Vinyl chloride monomer 2
5.5 kg was charged and the temperature was raised to 57 ° C. afterwards,
A total of 0.05% (relative to vinyl chloride) of hydrogen peroxide-formaldehyde sodium sulfoxylate redox polymerization initiator was continuously added while controlling the addition rate so as to maintain a constant polymerization rate. An approximately 8% aqueous solution of sodium lauryl sulfate was continuously added at a rate of approximately 0.1 l / hour from the time when the polymerization rate reached 10% to the end of the polymerization.

From the time when the reaction rate reached 15%, a total of 70 kg of vinyl chloride was added at a rate of 12 kg / 20 minutes. When the polymerization pressure dropped 1 kg / cm ² from the saturation pressure of vinyl chloride at 57 ° C., the addition of the initiator was stopped to stop the polymerization, and unreacted vinyl chloride was recovered. The obtained latex contained polymer particles having an average particle size of 0.9 μ and had a solid content concentration of 39.6% by weight. The latex was concentrated by ultrafiltration to a solid content concentration of 43.6% by weight.

(2) Production of vinyl chloride resin powder (B) for paste A part of the latex (A-2) produced as described above was spray dried under the following conditions. A commercially available product as the resin powder (B), a particle size and the like are also shown.

[Table 1] Resin powder spraying mechanism Exhaust air temperature Average particle size Shape Crush strength (B-1) Rotating disk 55 ° C 60μ Spherical 10g / mm ² (B-2) Two-fluid nozzle 60 ° C 30μ Spherical 90g / mm ² ( B-3) Grinding (B-1) 5μ Variant 10g / mm ² > (B-4) Commercial paste 35μ Spherical> 1000g / mm ² Admixture resin

(3) Method for producing granular resin The above latex (A) and resin powder (B) are shown in Table 1 respectively.
After mixing at a ratio shown in (1) to form a high-concentration latex, the latex was spray-dried using a rotating disk at an exhaust air temperature of 50 ° C. to produce various granular resins. The latex (A) and the powder (B) were mixed by continuously adding and dispersing the powder while stirring the latex. The physical properties of the granular resin are shown in Table 1.

[0028]

[Table 2]

A plastisol was prepared from the obtained granular resin, and its viscosity was measured. The results are shown in Table 2.

[0030]

[Table 3]

[0031]

According to the method of the present invention, a large granular resin of 50 μm or more can be produced from the latex containing the fine vinyl chloride resin particles obtained by the emulsion polymerization method or the fine suspension polymerization method. Granule resin has less powdering, has good powder fluidity, and enables automatic weighing.
Packaging, transportation, etc. have become easier and its handling has been improved. The resin is excellent in heat melting property even though it has a particle size similar to that of a vinyl chloride resin produced by a suspension polymerization method, and is a rotational molding, Engel method, Heisler method,
It is suitable as a resin raw material for powder molding such as the Hayashi process.

Further, since the granular resin is composed of fine particles and larger particles, the surfaces of at least two different particle sizes, each of which is hardened with a loose fusion force, make the granular resin of one kind of fine particles. The penetration of the plasticizer is faster than that of the plasticizer, and the granules disintegrate more easily by stirring in the plasticizer to form a low-viscosity paste sol, which has excellent viscosity stability over time and good flowability in the high shear region. Therefore, it is not necessary to mix it with another mixing resin or the like.

The granular resin produced by the method of the present invention can be used as an alternative to the vinyl chloride resin produced by the suspension polymerization method, and as a resin having a good heat-melting property, extrusion molding, injection molding, calendering, powder molding. And various other molding methods. In addition, the granular resin produced by the method of the present invention is useful as a resin for paste processing and can be used for applications such as high speed coating, rotary screen printing, spray coating, and dipping.

Claims (12)

[Claims] 1. Granules characterized by mixing a polyvinyl chloride latex (A) obtained by an emulsion polymerization method or a fine suspension polymerization method with a vinyl chloride resin powder (B) for paste and then spray-drying the mixture. Resin manufacturing method. 2. The method for producing a granular resin according to claim 1, wherein the polyvinyl chloride latex (A) is used after removing coarse particles larger than 65 μ generated in the polymerization process. 3. The method for producing a granular resin according to claim 1, wherein the vinyl chloride polymer or copolymer in the polyvinyl chloride latex (A) is fine particles of 3 μm or less. 4. Vinyl chloride resin powder (B) for paste
2. The method for producing a granular resin according to claim 1, wherein the polyvinyl chloride latex (A) is spray-dried. 5. The method for producing a granular resin according to claim 4, wherein the spray drying temperature of the polyvinyl chloride latex (A) is 50 ° C. or higher at the outlet of the drying device. 6. A vinyl chloride resin powder for paste (B)
The method for producing a granular resin according to claim 1, wherein is a resin for mixing paste. 7. A vinyl chloride resin powder (B) for paste.
7. The method for producing a granular resin according to claim 1, claim 4 or claim 6, wherein the method does not include coarse particles having a particle size of more than 150 μm. 8. A vinyl chloride resin powder for paste (B)
The method for producing a granular resin according to claim 7, wherein the average particle size is 5 to 45 μm. 9. A vinyl chloride resin powder (B) for paste.
8. The method for producing a granular resin according to claim 7, wherein the average particle size of the resin is less than 5 μm. 10. The method for producing a granular resin according to claim 1, wherein the solid content concentration of the latex after mixing the vinyl chloride resin powder for paste (B) is 50 to 75% by weight. 11. The method for producing a granular resin according to claim 1, wherein the spray-drying temperature is 55 ° C. or lower at the temperature of the airflow outlet of the spray-drying device. 12. The method for producing a granular resin according to claim 1, wherein the average particle size is 50 to 300 μm.