JPS646664B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a vinyl chloride resin composition that has good gelling properties and good kneading properties in a molding process. Traditionally, vinyl chloride resins produced by emulsion polymerization or fine suspension polymerization have a higher gelling property than vinyl chloride resins with the same degree of polymerization obtained by suspension polymerization or bulk polymerization. Although it has good properties, it has the major drawbacks that it generates a lot of powder during handling during molding, has poor thermal stability, and has high drying costs because it undergoes spray drying.As a result, the price of vinyl chloride resin is high. There are limits to its uses other than that, and it has not yet been put to practical use. The present inventor has conducted extensive studies on a method for producing a resin composition that is produced by emulsion polymerization or microsuspension polymerization without losing the gelling properties of vinyl chloride resin, does not cause dusting, and has excellent thermal stability. As a result, they discovered that a composition with good gelatinability and thermal stability could be obtained by adding a plasticizer to the latex or microdispersion after vinyl chloride polymerization to gel it, and centrifugally dehydrating it. The invention has been achieved. That is, the object of the present invention is to process a latex or fine dispersion liquid after polyvinyl chloride polymerization through a centrifugal dehydration and drying process without undergoing spray drying, thereby producing a material with excellent gelability, kneadability, and thermal stability. The present invention provides a method for producing a vinyl chloride resin composition. The gist of the present invention is to mix a plasticizer with a vinyl chloride resin latex or finely dispersed emulsion or dispersion system, to transfer and absorb the plasticizer into the vinyl chloride resin, and after absorption or The method of producing a vinyl chloride resin composition comprises gelling the vinyl chloride resin at the same time as absorption and then separating the aqueous phase. The method of the present invention will be explained in detail. The latex or fine dispersion of vinyl chloride resin (hereinafter simply referred to as latex) that can be used in the method of the present invention is a mixture of vinyl chloride or vinyl chloride and a comonomer copolymerizable therewith, such as vinyl acetate, acrylic acid, methyl acrylate, etc. Preferably, the latex is produced by a conventional emulsion polymerization method or by a microsuspension polymerization method. The comonomer copolymerizable with vinyl chloride is not limited to the above-mentioned specific examples, and the type of emulsifier or suspending agent used during polymerization is not particularly limited either. In addition, the latex may contain a polymerization aid added before or during polymerization, or a powdered filler such as calcium carbonate, as long as it does not adversely affect the production of the vinyl chloride resin composition described below. Furthermore, the latex after polymerization may contain various physical property improving aids or processing aids such as lipophilic heat stabilizers, colorants, ultraviolet absorbers, antioxidants, lubricants, and fillers. . Although the solid content concentration of the latex varies depending on the bath ratio of the polymerizable monomer and water, additives, and the degree of polymerization, it is preferable to have a higher solid content in consideration of the addition of plasticizer, water separation, the size of the equipment, etc. Usually, it is desirable to use 30% by weight or more of the total latex. The plasticizer used in the method of the present invention is not particularly limited, and may be any of a variety of plasticizers that can be used as plasticizers for vinyl chloride resins. For example, phthalate plasticizers such as dibutyl phthalate, diheptyl phthalate, dioctyl phthalate, diisodecyl phthalate, butyl lauryl phthalate, ditridecyl phthalate, butyl benzyl phthalate, butyl phthalyl butyl glycolate, and tributyl trimellitate. , trimellitic acid plasticizers such as triheptyl trimellitate and trioctyl trimellitate, polyester plasticizers obtained by condensation of polybasic acid and glycol,
Phosphate ester plasticizers such as tricresyl phosphate and trioctyl phosphate, tri-n-butyl citrate, dioctyl adipate, dioctyl azelaate,
Examples include fatty acid ester plasticizers such as dioctyl sebacate and methyl acetyl ricinoleate, and epoxy plasticizers such as alkyl epoxy stearate and epoxidized soybean oil. These plasticizers are used singly or in combination of two or more. can. The amount of plasticizer mixed into the latex varies depending on the gelling conditions of the latex, granulation conditions, separation operation, and various conditions of the final use of the vinyl chloride resin composition, but the amount of plasticizer mixed with the latex varies depending on the various conditions of the latex gelling conditions, granulation conditions, separation operation, and end use of the vinyl chloride resin composition. It is desirable to use 10 parts by weight or more, particularly preferably in the range of 30 to 100 parts by weight. If the amount of plasticizer is less than 10 parts by weight based on 100 parts by weight of the solid content in the latex, the plasticizer will not be uniformly dispersed in the vinyl chloride resin, which is undesirable in terms of the quality of the vinyl chloride resin composition. At the same time, it becomes partially pulverized and difficult to granulate. In addition, if the amount exceeds 100 parts by weight, the plasticizer tends to become a continuous phase and it becomes difficult to obtain an appropriately granulated vinyl chloride resin composition, although this will vary depending on the gelling temperature and gelling conditions such as stirring. be. The method of the present invention involves adding a plasticizer to the above-mentioned latex emulsion system or dispersion system, stirring the mixture, and transferring and absorbing the plasticizer into the vinyl chloride resin.
If necessary, the latex is heated to gel after or simultaneously with the absorption of the plasticizer, and stirring is continued until the vinyl chloride resin composition that has absorbed the plasticizer is completely separated from the water, and the upper aqueous phase is removed. and the lower layer of the vinyl chloride resin composition phase are separately separated. Of course, the method of the present invention also includes the case where a plasticizer containing a destroyed latex emulsion or dispersion system is added. The timing of adding the plasticizer to the latex is not particularly limited, but it can be added to the latex at any time after vinyl chloride polymerization. In the method of the present invention, in order to speed up the transfer and absorption of the plasticizer into the vinyl chloride resin, the emulsion system or dispersion system (hereinafter simply referred to as the dispersion system) of the vinyl chloride resin latex is destroyed to cause gradual aggregation in the paste resin. It is preferable to add the plasticizer after the heating. Methods for destroying the dispersion system of vinyl chloride resin latex include, for example, applying mechanical shearing force such as high-speed stirring, irradiating with ultrasonic waves, heating with steam, etc., and using electrolytes such as alum and calcium chloride. Various methods have been adopted, including adding acid or alkali such as hydrochloric acid or caustic soda to decompose the dispersant, adding a polymer flocculant such as polyacrylamide, and freezing with a cryogen. Ru. If the latex dispersion system is insufficiently broken, the transfer of the plasticizer to the vinyl chloride resin will be delayed, and in some cases, the aqueous phase may become cloudy with fine particles of the vinyl chloride resin. Furthermore, when to add plasticizer to latex,
It is preferable to carry out the reaction at a temperature at which the vinyl chloride resin in the latex quickly absorbs the plasticizer and gelation easily occurs. Preferably, the temperature is in the range of 40 to 140°C. When a plasticizer and latex are mixed at a temperature of 40°C or higher, the plasticizer is rapidly absorbed into the vinyl chloride resin, and although there are differences depending on the type and composition of the vinyl chloride resin, it is relatively easy to do so in all cases. gelation occurs. Of course, if the plasticizer is added at a temperature below 40°C, it can be easily gelled by transferring and adsorbing the plasticizer to the vinyl chloride resin and then raising the temperature.
However, processing at temperatures above the melting temperature of vinyl chloride resin will cause the resins produced by emulsion polymerization and microsuspension polymerization to lose their characteristics, so it is usually desirable to process at temperatures below 140°C. . In the method of the present invention, it is also possible to use a hydrophobic diluent such as texanol isobutyrate, dodecylbenzene, kerosene, mineral spirits, etc. together with the plasticizer, if necessary. However, if the diluent has low affinity with the vinyl chloride resin, phase separation may not be successful. The absorption of the plasticizer is determined in relation to the time and area of contact between the vinyl chloride resin and the plasticizer, and the temperature. Stirring operations are commonly employed to increase contact between resin and plasticizer. The type of stirring operation is not particularly limited, but generally includes simple mechanical stirring, stirring using a jet pump, stirring using an air ring, and the like. In the present invention, it is particularly preferable to use a stirrer with a slightly larger power, and it is also possible to use a wet pulverizer if necessary. In the method of the present invention, by using a stirrer or a wet grinder in the transfer absorption and gelation steps, the particles in the latex state (agglomerated particles) are granulated while being retained. To carry out the method of the present invention, for example, a plasticizer is added to the latex after vinyl chloride polymerization and the dispersion system of the latex is destroyed, or a plasticizer is added after the dispersion system of the latex is destroyed, and as necessary. Warm, heat and stir. As the plasticizer is transferred to and absorbed by the vinyl chloride resin, gelation occurs, and the vinyl chloride resin composition containing the plasticizer and water separate. The speed and time of stirring after adding the plasticizer to the latex are not particularly limited, but it is sufficient that the vinyl chloride resin containing the plasticizer is granulated and the aqueous phase is completely separated. After that, either reduce the agitation or leave it still to remove the upper aqueous phase by decantation, or dehydrate it by centrifugation, dry it in a shelf dryer,
It is dried in a dryer such as a fluidized dryer or a rotary kiln that is normally used for vinyl chloride resin produced by suspension polymerization. In addition, before drying, in order to remove impurities such as emulsifiers, dispersants such as suspending agents, and electrolytes used to destroy the dispersion system contained in the composition, pure water is added and stirring and dehydration are repeated as necessary. It is also possible. When using the vinyl chloride resin composition produced by the method of the present invention, plasticizers, diluents, ultraviolet absorbers, colorants, heat stabilizers, antioxidants, blowing agents, blowing aids, fillers, etc. Additives (materials) used for ordinary vinyl chloride resins can be added as appropriate. According to the method of the present invention, compared to the conventional powder mist drying method of vinyl chloride resin using the emulsion polymerization method, not only the problem of energy saving in the drying process and the problem of dusting when handling the powder is solved, but also Taking advantage of the characteristics of vinyl chloride resin produced by emulsion polymerization or fine suspension polymerization, a vinyl chloride resin composition with better meltability, less buildup, and excellent processability can be obtained. Additionally, the composition can be made more effective by granulating or pulverizing it during the gelling step.
For example, the composition produced by the method of the present invention is
The particle size can be easily controlled by pulverizing and then classifying, and its utility value is high as a resin composition for powder molding. Furthermore, various molding methods such as extrusion molding, injection molding, calendar processing, and rotational molding can be applied to the composition obtained by the method of the present invention. The method of the present invention will be explained below in detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. Example 1 After pre-emulsifying 100 parts by weight of vinyl chloride, 100 parts by weight of water, 1 part by weight of sodium dodecylbenzenesulfonate and 0.15 parts by weight of lauroyl peroxide, polymerization was carried out at 50°C for 15 hours. A portion of the vinyl chloride resin latex thus obtained was taken out into a container equipped with a stirrer, and the dispersion system was disrupted using the following various methods. (i) Add 0.5 parts by weight of calcium chloride to 100 parts by weight of solids in the latex (ii) Stir vigorously using a colloid mill (5000 rpm) (iii) Heat with steam (iv) Cool externally with a cryogen After freezing, leave at room temperature. Add a plasticizer (a) to the latex, whose dispersion system has been destroyed and loosely agglomerated by the above method, in an amount equivalent to 40 parts by weight per 100 parts by weight of solids in the latex. ) (B) Diisodecyl phthalate (DIDP) (C) Dioctyl adipate (DCA) (D) Butylbenzyl phthalate (BBP) (E) Dibutyl phthalate (DBP) are added to each, and when stirred for 10 minutes, the plasticizer becomes a resin phase. The mixture was separated into upper and lower layers. The upper layer consisted of an almost transparent aqueous phase, and the lower layer was a resin phase to which the plasticizer had migrated. Moreover, floating plasticizer, which has a specific gravity lower than water, was not observed on the liquid surface of the upper layer, and all of the plasticizer was contained in the composition layer. The obtained mixed phase was heated to 80° C. while stirring to gel and form granules. The obtained slurry was dehydrated and dried to obtain a vinyl chloride resin composition. Amount of resin in the obtained vinyl chloride resin composition
Heat stabilizer (barium-zinc type) per 100 parts by weight
3 parts by weight, 0.2 parts of lubricant (stearic acid),
Table 1 shows the results of kneading with a mill roll at 160° C. to form a film, and comparing the number of fish eyes in the obtained film in relation to the kneading time. For comparison, a paste resin obtained by spray drying (1), a resin obtained by coagulation drying (2), and a resin obtained by suspension polymerization with the same degree of polymerization (3) were also evaluated in the same manner as in Example 1. did. However, in the comparative example, the plasticizer was only DOP.

[Table] Note Mill roll kneading conditions: 160°C for 2 minutes and 5 minutes Evaluation: Grade 3 in the comparative example is rated as normal, better than that is graded 2, excellent is grade 1, and worse than that is graded 4. . From the results in Table 1, the compositions produced by the method of the present invention are extremely good compared to the compositions of Comparative Examples 1, 2, and 3. Comparative Example 1 was quite good, but since it was a fine powder, it was difficult to obtain a uniformly dispersed blend due to severe dusting during blending. Example 2 In a 100 glass lined autoclave,
00 parts by weight of ion-exchanged water and 3 parts by weight of vinyl chloride seed polymer latex having a unit particle size of 0.4 μm and an average degree of polymerization of 1500 were charged as polymer components. Then, degassed under reduced pressure, added 97 parts by weight of vinyl chloride, and lowered the temperature to 50%.
℃ to start the polymerization reaction, and the total amount
0.015% by weight (based on vinyl chloride) of potassium persulfate and 5 molar equivalent (based on potassium persulfate) of sodium bisulfite were added continuously through separate inlet tubes throughout the entire polymerization time. In addition, the polymerization rate
A latex of vinyl chloride resin was produced by continuously adding sodium lauryl sulfate as an emulsifier at a rate of 0.01% by weight per hour to vinyl chloride from the time when the concentration reached 15% by weight until the reaction pressure began to drop.
To this latex, 40 parts by weight of the plasticizer dioctyl phthalate was added based on 10 parts by weight of the solid content of the latex, and a vinyl chloride resin composition was produced in the same manner as in Example 1 (i). The results of the fisheye test similar to Example 1 were extremely good. Example 3 In the method for producing latex of vinyl chloride resin in Example 1, a latex was produced in the same manner as in Example 1, except that 100 parts by weight of vinyl chloride was replaced with a mixture of 95 parts by weight of vinyl chloride and 5 parts by weight of vinyl acetate. Manufactured. A vinyl chloride resin composition was prepared in the same manner as in Example 1 (i) by adding 40 parts by weight of dioctyl phthalate per 100 parts by weight of solid content in the latex. The results of the same physical test as in Example 1 were extremely good.

Claims (1)

[Scope of Claims] 1. Mixing a plasticizer with a vinyl chloride resin latex or microdispersion in which the emulsion or dispersion system is destroyed, and transferring and absorbing the plasticizer into the vinyl chloride resin, and after absorption or absorption. A method for producing a vinyl chloride resin composition, which comprises simultaneously gelling a vinyl chloride resin and then separating an aqueous phase. 2. The method for producing a vinyl chloride resin composition according to claim 1, wherein a plasticizer is mixed into the latex or fine dispersion after breaking the emulsion or dispersion system of the latex or fine dispersion. 3. The method for producing a vinyl chloride resin composition according to claim 1 or 2, wherein the gelling temperature is in the range of 40 to 140°C. 4. A method for producing a vinyl chloride resin composition according to claim 1, 2, or 3, wherein granulation is performed simultaneously with gelation.