JPS5912956A - Manufacture of polyvinyl chloride resin composition - Google Patents

Abstract

PURPOSE:To obtain titled composition at low cost, with excellent thermal stability and good gelling ability, also free from dusting, by incorporating a plasticizer in a PVC latex or fine PVC dispersion to make it transfer to and absorb in the resin, followed by gelling, then separating the aqueous phase. CONSTITUTION:A PVC latex or fine PVC dispersion (pref. prepared by an emulsion polymerization or fine suspension polymerization) is incorporated, following destruction of the emulsified or dispersed system, with at least 10 (especially 30-100) pts.wt., based on 100pts.wt. of the solid resin, of a plasticizer to make it transfer to and absorb in the resin. Concurrent with the absorption or subsequent to that, the PVC resin is gelled (pref. at 40-140 deg.C), followed by separating the aqueous phase, then drying to obtain the objective composition. EFFECT:Capable of eliminating requirement of expensive spray drying process thus leading to reduction in the resin cost.

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 cross-talk properties in the molding process.

Traditionally, vinyl chloride resins produced by emulsion polymerization or micro-suspension polymerization have a high gelling property, but they generate a lot of powder when handled during molding, have poor thermal stability, and The big drawback is that the drying cost is high because it goes through spray drying, and the price of the vinyl chloride resin is high.
There are limits to its uses other than as a base resin, and it has not yet been put to practical use.

The present inventor has conducted extensive research 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 of R=j, a composition with good gelability and thermal stability can be obtained by adding a plasticizer to the still fine dispersion of latex after vinyl chloride polymerization to gel it, and then centrifugally dehydrating it. The present invention was achieved by discovering that

That is, the object of the present invention is to process a latex or a fine dispersion liquid after polyvinyl chloride polymerization through centrifugal dehydration and drying steps without undergoing spray drying, thereby producing a material with excellent gelling properties, kneading properties, and thermal stability. The present invention provides a method for producing a vinyl chloride resin composition.

Therefore, the gist of the present invention is to mix a latex or fine dispersion of vinyl chloride resin with a plasticizer, transfer the plasticizer to the vinyl chloride resin and absorb it, and gel the vinyl chloride resin after or simultaneously with the absorption. The method of producing a vinyl chloride resin composition comprises the steps of:

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 composed of vinyl chloride or vinyl chloride and a comonomer copolymerizable therewith, such as vinyl acetate, acrylic acid, methyl acrylate, etc. Preferably, the mixture is a latex produced by conventional emulsion polymerization techniques or by microsuspension polymerization techniques.

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 contains lipophilic heat stabilizers, colorants, ultraviolet absorbers, antioxidants,
Various physical property improving aids or processing aids such as lubricants and fillers may be added.

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 a plasticizer, water separation, the size of the equipment, etc. It is usually desirable to use a latex with a total content of 30% by weight or more.

The plasticizer used in the method of the present invention may be of various types as long as it is used as a plasticizer for vinyl chloride resin.
It is not particularly limited.

For example, phthalate ester plasticizers such as dibutyl phthalate, diheptyl phthalate, dioctyl phthalate, diisodecyl phthalate, butyl lauryl phthalate, ditritenyl 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,
Totsu I]-butyl citrate, dioctyl adipate,
Fatty acid Nisderian plasticizers such as dioctyl azetuate, dioctyl sebacate, methyl acetyl ricinoleate,
Examples include epoxy plasticizers such as alkyl epoxy stearate and epoxidized soybean oil, and these plasticizers can be used alone or in combination of two or more.

The amount of plasticizer mixed into the latex varies depending on various conditions such as gelling conditions of the latex, granulation conditions, separation operation, and final use of the vinyl chloride resin composition. It is desirable to use 70 parts by weight or more, particularly preferably in the range of 30 to /θyW. If the amount of plasticizer is less than 70 parts by weight based on 700 parts by weight of the solid content in the latex, the plasticizer will not be uniformly dispersed in the vinyl chloride resin, which may affect the quality of the vinyl chloride resin composition. It brings about desirable properties, and also becomes partially fine and difficult to granulate.Also, if it exceeds 100 parts by weight, it will vary depending on the degree of gelation and gelling conditions such as stirring. The plasticizer tends to become a continuous phase, and there is a tendency for a suitably granulated vinyl resin composition to become a solid phase.

Add and stir to transfer and absorb the plasticizer into the vinyl chloride resin, and if necessary, heat the latex to gel after or simultaneously with the absorption of the plasticizer, to obtain a vinyl chloride resin composition that has absorbed the plasticizer. Stirring is continued until the mixture is completely separated from water, and the upper aqueous phase and the lower vinyl chloride resin composition phase are separately separated. Of course, the method of the present invention also includes the case where latex is added to the plasticizer.

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.

However, 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 was destroyed, causing gentle aggregation in the paste resin. Preferably, the plasticizer is added afterwards. Methods for destroying the dispersion system of vinyl chloride resin latex include, for example, applying root-like shearing force such as high-speed stirring, irradiating with ultrasonic waves, heating with steam, etc., and using electrolytes such as alum and calcium chloride. There are various methods such as adding acid or alkali such as hydrochloric acid or caustic acid or alkali to decompose the dispersant, adding a polymer flocculant such as polyacrylamide, and freezing with a cryogen. Adopted.

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, it is preferable to add the plasticizer to the latex at a temperature at which the vinyl chloride resin in the latex can quickly absorb the plasticizer and gelation can easily occur. The temperature is q
A range of θ to /90°C is desirable. When plasticizer and latex are mixed at a temperature above qo℃, absorption into the vinyl chloride resin before plasticization occurs rapidly, and although there are differences depending on the type and composition of the vinyl chloride resin, in all cases it is relatively easy. Gelation occurs.

Of course, if a plasticizer is added at a temperature below lIo℃, the plasticizer will be adsorbed onto the transferable vinyl chloride resin and then the temperature will increase at t11+.
By A, gelation can be easily achieved. However, processing at a temperature higher than the melting temperature of vinyl chloride resin causes the resins produced by emulsion polymerization and fine suspension polymerization to lose their characteristics, so usually /l/
It is desirable to process at a temperature of θ°C or lower.

In the method of the present invention, it is also possible to use a water dispersing diluent such as texanol imbutyrate, dodecylbenzene, dissolved oil, mineral spirit, etc. together with the plasticizer when adding the plasticizer, if necessary. However, if the diluent is a vinyl chloride resin and has poor wearability, phase separation may not be successful.

- Absorption of plasticizer is determined by the relationship between time and area of contact between vinyl chloride resin and plasticizer, and temperature. Stirring operations are generally employed to increase contact between resin and plasticizer. The type of stirring operation is not particularly limited, but
Generally simple mechanical stirring, jet pump stirring,
Examples include stirring by nearing.

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, particles in a latex state (agglomerated particles) are maintained and granulated in about i.

To carry out the method of the present invention, for example, a plasticizer is added to the latex after vinyl chloride polymerization, the dispersion system of the latex is broken if necessary, and the mixture is heated and stirred. As the plasticizer migrates and is absorbed by the vinyl chloride resin, gelation occurs, and although the vinyl chloride resin composition containing the plasticizer and water are not separated, the vinyl chloride resin containing the plasticizer becomes granular. It is sufficient that the aqueous phase is completely separated.

After that, the agitation is weakened or left to stand still to remove the upper aqueous phase by decontamination, or the water is removed by centrifugation, and then the suspension polymerization is carried out using a conventional suspension polymerization method such as a shelf dryer, flow dryer, or rotary kiln. It is dried in a dryer used for manufactured vinyl chloride resin. In addition, before drying, in order to remove impurities such as dispersants such as emulsifiers and suspending agents contained in the composition and electrolytes used to destroy the system, add pure water and stir and dehydrate. It is also possible to repeat.

When using the vinyl chloride resin composition produced by the method of the present invention, it is necessary to use ordinary materials such as plasticizers, diluents, ultraviolet absorbers, colorants, heat stabilizers, antioxidants, blowing agents, blowing aids, and fillers. The end result is to appropriately add additives (materials) used for vinyl chloride resin.

According to the method of the present invention, compared to the conventional emulsion polymerization method of powder mist drying of vinyl chloride resin, problems such as energy saving, energy consumption, and dusting during powder handling can be solved in the drying process. In addition, by taking advantage of the characteristics of the vinyl chloride resin itself produced by emulsion polymerization or fine suspension polymerization, it becomes a vinyl chloride resin composition with better meltability, less Finch eye, and excellent processability. Also, the composition can be made more effective in its characteristics by being granulated or pulverized during the gelling process. For example, the composition of the present invention can easily control the particle size by pulverizing and then classifying it, and has high utility value as a resin composition for powder molding.

In addition, various molding methods such as extrusion molding, extrusion molding, calendar processing, rotational molding, etc. can be applied to the composition obtained by the method of the present invention.

The method of the present invention will be described 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/ 100 parts by weight of vinyl chloride, water/θ0 parts by weight, 71,111 parts of sodium dodecylbenzenesulfonate, and 0.0 parts of lauroyl oxide. '! After pre-emulsifying r Mm time, polymerization between /S and 50°C was carried out,
cormorant. - 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.

(1-) Add parts by weight of calcium chloride θ, S to the solid content/θθ in the latex (strong stirring using a colloid mill (A; 000 rpm), steam heating, external cooling with cryogen The dispersion system is destroyed by the above-mentioned method, and the latex is left to stand at temperature after freezing.
Plasticizer in an amount equivalent to parts by weight of y-O (a) Dioctyl phthalate (DOP) (b) Diindecyl phthalate) (DIDP) (c) Dioctylaziba-) (DOA)) Butylbenzyl phthalate l- (BBP) ゛(Bodyptyl phthalate (D)
BP) were respectively added and stirred for 70 minutes, the plasticizer was transferred to the resin phase and 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 that of 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 0.degree. C. while stirring to gel and granulate. The obtained slurry was dehydrated and dried to obtain a vinyl chloride resin composition. The amount of resin/θO weight in the obtained vinyl chloride resin composition is 3 parts by weight of heat stabilizer (barium-zinc type) per part. , blended with 0.2 parts of lubricant (=thenic acid), /l, o c
Table 1 shows the results obtained in relation to the kneading time for the number of fins of the film that was kneaded using a mill roll and filtered.

Paste resin (1) obtained by spray drying for comparison
Resin (2) obtained by coagulation drying and resin (3) obtained by suspension polymerization having the same degree of polymerization were also evaluated in the same manner as in Example.

However, in the comparative example, only DOP was used as the plasticizer, causing distortion.

Note) For the evaluation of mill ° roll cross-wire conditions it, o ℃ - min and Sj min, the 3rd grade in the comparative example is normal, the better than that is 2nd, the excellent is 7th grade, that's the comparative example/, It is extremely good compared to the composition of λ, 3. Comparative Example / was quite good. Since it was a fine powder, it caused a lot of dusting during blending (it was difficult to obtain a uniformly dispersed blend). In an autoclave, 100 parts by weight of ion-exchanged water and unit particles 1 diameter o,
Vinyl chloride seed polymer latex having an average degree of polymerization of yμ and isoθ was charged in triplicate as a polymer component, and a portion of 1λ was charged. After that, it was degassed under reduced pressure, and 97 parts by weight of vinyl chloride was added.
The temperature was raised to 50°C to start the polymerization reaction, and a total amount of 0.0/31% (based on vinyl chloride) of potassium persulfate and S mole equivalent (based on potassium persulfate) of sodium hydrogen sulfite were added respectively. Addition was made continuously from a separate inlet tube to the total polymerization time. In addition, sodium lauryl sulfate was used as an emulsifier from the time the polymerization rate reached /S weight u% until the reaction pressure started to drop. It was continuously added to vinyl chloride at a rate of 0.07% by weight per hour to produce a latex sheet of vinyl chloride resin. Add the plasticizer dioctyl phthalate to this latex at 100 parts by weight of the latex solid content (
On the other hand, a vinyl chloride resin composition was produced in the same manner as in Example 1 (1) by adding 70 parts of vinyl chloride.

The results of the similar Finnish Eye test in Example 7 were very good as in Example 7. A latex was produced in the same manner as in Example 1, except that a mixture of 1 part by weight of vinyl chloride 95 and 1 part by weight of vinyl acetate S was used. A vinyl chloride resin composition was produced in the same manner as in Example (1) by adding 100 parts by weight of dioctyl phthalate (solid content in the latex) to the latex.

The results of the Fin Shuai test similar to Example/Same were extremely good as in Example/Similar to Example/Same.

Patent applicant Mitsubishi Monsanto Chemical Co., Ltd. Representative
Person Patent Attorney Hase Yo − Others/Names

Claims (3)

[Claims] (1) Mix the latex or fine dispersion of vinyl chloride resin with a plasticizer, transfer the plasticizer to the vinyl chloride resin and absorb it, gel the vinyl chloride resin after or simultaneously with the absorption, and then add water to the vinyl chloride resin. Method for producing a vinyl chloride resin composition comprising separating phases (2) The method for producing a vinyl chloride resin composition according to claim 1, which comprises mixing a plasticizer into the latex or fine dispersion after destroying the emulsion or dispersion system of the latex or fine dispersion. (3) A method for producing a vinyl chloride resin composition according to claim 1 or 2, wherein the gelling temperature is in the range of IIo to /I0°C (patent for granulating at the same time as gelling) A method for producing a vinyl chloride resin composition according to item 1, item λ, or item 3