JPH0419243B2 - - Google Patents

Description

Claim 1 Homopolymer of vinyl chloride or vinyl chloride and at least one terminal of one or more types.
A method for producing a copolymer with a copolymerizable olefinic monomer having a CH ₂ =C group, comprising: (a) the monomer to be polymerized, and (b) an aqueous reaction medium, and (c) the polymerizable monomer. For 100 parts by weight of monomer
0.01 to 0.5 parts by weight of a water-insoluble, free radical-forming catalyst, and (d)() 0.6 to 1.2 parts by weight of long-chain saturated fatty acids containing 8 to 20 carbon atoms per 100 parts by weight of monomer. and () 0.1 to 1.0 parts by weight per 100 parts by weight of monomer. forming a monomer premix containing an emulsifier system consisting of a water-insoluble plasticizer; (B) homogenizing the entire premix at a temperature below the reactivity of the catalyst used; (C) dissolving the homogenized premix; In the reaction zone, keep the pH between 2.0 and 2.0 until the reaction is complete.
10.5 at a temperature in the range from 30 to 70<0>C, (D) then recovering the polymer or copolymer. 2. The emulsifier system comprises at least one long straight chain unsaturated alcohol containing 12 to 24 carbon atoms,
2. The method according to claim 1, wherein the ratio of alcohol to emulsifier is 1.0 or less. 3. The method according to claim 1, wherein the plasticizer is dioctyl phthalate. 4. The method according to claim 1, wherein the plasticizer is epoxidized soybean oil. 5. The method according to claim 1, wherein the plasticizer is dioctyl adipate. 6. The method of claim 1, wherein the catalyst is bis(4-tert-butylcyclohexyl) peroxydicarbonate. 7. The method according to claim 1, wherein the catalyst is di(2-ethylhexyl)peroxydicarbonate. 8. The method according to claim 1, wherein the catalyst is diisononanoyl peroxide. 9. The method of claim 2, wherein the emulsifier system comprises sodium lauryl sulfate. 10. The method of claim 2, wherein the emulsifier system comprises sodium alpha olefin sulfonate. 11. The method according to claim 10, wherein the PH is in the range of 5.0 to 10.5. 12. The method according to claim 11, wherein the plasticizer is dioctyl phthalate. 13. The method of claim 12, wherein the catalyst is bis(4-tert-butylcyclohexyl) peroxydicarbonate. BACKGROUND OF THE INVENTION In conventional emulsion polymerization processes, it has been difficult to obtain a suitable latex because the latex usually contains particles of various sizes and is either too fine or too large. In addition to particle size uniformity, other properties of resins produced by emulsion polymerization such as plastisol viscosity, transparency, and gel temperature, as well as bloom and bleed in the products produced from them. Things need to be improved. Various reports have been made to successfully improve these properties, but the final desired success has not been achieved. For example, the use of a variety of different emulsifiers and catalysts has been reported. It has also been suggested to vary the polymerization conditions. However, in most of these cases too much coagulation occurs, resulting in a latex containing too many coagulums or partially agglomerated particles, which can settle and reduce the yield. -ing The shelf life of such latexes is often imperfect.
It is desirable to have a latex that changes little during storage in terms of viscosity and retains good thermal stability. One of the main difficulties in producing vinyl dispersion resins or polymers by emulsion polymerization techniques is that large amounts of emulsifiers and soaps must be used. These high amounts not only lead to high raw material costs but, more importantly, limit the desirable resin properties that can be achieved by proceeding with emulsion polymerization. It would be highly desirable to reduce the amount of emulsifier or soap required in polymerization formulations. Another disadvantageous problem in the commercial production of vinyl halides and vinylidene polymers and copolymers is that when polymerized alone or with other copolymerizable monoolefinic monomers with end groups CH ₂ ═C, the inner surface of the reactor formation of undesirable polymer build-up. This build-up is particularly severe when large amounts of emulsifier are used. This deposit or build-up on the reactor surface not only impedes heat transfer but also reduces productivity and has a consequent detrimental effect on the viscosity and quality of the polymer, such as producing finer particles than desired. will have an adverse effect on
Obviously, this polymer buildup must be removed, and their removal is difficult and time consuming. Of course, it is most desirable to have a polymerization process in which polymer build-up does not occur or is minimized and in which the build-up is "grainy" or easily removed. SUMMARY OF THE INVENTION When producing vinyl dispersion polymers and copolymers in the emulsion polymerization of vinyl monomers, a substantial reduction in the amount of emulsifier required is achieved by adding small amounts of water-insoluble plasticizers to the polymerization formulation. It was unexpectedly discovered that it was possible.
Furthermore, it has been found that by using a water-insoluble initiator and by homogenizing the entire reaction mixture before polymerization, the foam properties of plastisols produced from the polymers are greatly enhanced. Add plasticizer to the stabilized monomer droplets during the premixing and homogenization stage to thus reduce the emulsifier without reducing the colloidal stability of the overall polymerization. A reduction in emulsifier concentration results in a substantial reduction in polymer build-up during polymerization. DETAILED DESCRIPTION In the present invention, "vinyl dispersion resin" refers to polymers and copolymers of vinyl chloride. Vinyl chloride may be copolymerized with one or more polymerizable olefinic monomers having at least one terminal group CH ₂ =C. α,β-olefinic unsaturated carboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, α-cyanoacrylic acid, etc. as olefinic monomers; methyl acrylate, ethyl acrylate, butyl acrylate Acrylic acid esters such as octyl acrylate, cyanoethyl acrylate, etc.; Methacrylic acid esters such as methyl methacrylate, butyl methacrylate, etc.; Nitriles such as acrylonitrile and methacrylonitrile; Methylacrylamide, N-methyloylacrylamide , N-butoxymethacrylamide, etc.; vinyl ethers such as ethyl vinyl ether, chloroethyl vinyl ether, etc.; vinyl ketones; styrene and styrene derivatives such as α-methylstyrene, vinyltoluene, chlorostyrene, etc.; vinylnaphthalene, allyl and Examples include vinyl chloroacetate, vinyl acetate, vinyl pyridine, methyl vinyl ketone and other polymerizable olefinic monomers of the type known to those skilled in the art. The present invention relates to vinyl produced by the polymerization of vinyl chloride alone or in a mixture with one or more olefinic monomers copolymerizable therewith in an amount up to about 80% by weight based on the total amount of monomers. It has particular application in the production of dispersed resins or pastes. The most preferred vinyl dispersion resin is polyvinyl chloride (PVC), and the present invention is extended in that context for simplicity and convenience, and is intended to be illustrative only and not limiting. I can understand that. It is noteworthy that until now it has been reported that vinyl monomers can be polymerized in the presence of plasticizers. See, for example, US Pat. No. 3,867,331, issued February 18, 1975. In this patent, emulsion polymerization methods are used such that the formulation includes a plasticizer. However, in said patent, the objective is to obtain as much plasticizer as possible in the final resin, unlike the objective of the present invention. The patent uses 5 to 100 parts by weight of plasticizer, preferably 15 to 90 parts by weight, far exceeding the amounts used here, as will be seen from the discussion below.
Nothing is stated by the patentee that plasticizers are used to reduce the amount of emulsifier used. In fact, the amount of emulsifier used in that invention is much higher than that used here, so that just the opposite must be implied. US Pat. No. 4,113,687, issued September 12, 1978, describes an emulsion polymerization process in which the formulation includes a solvent for the monomers. That patent also uses a water-soluble initiator as opposed to the water-insoluble initiator used in the present invention.
Further in that patent, a portion of the water and a substance (solvent) that dissolves the emulsifier and monomer are homogenized to form an emulsion. The remaining water plus the monomer or monomer mixture plus the water-soluble initiator is then added to the emulsion with normal stirring. In the present invention, all reaction mixtures are homogenized together and fed into the reactor. An important aspect of the present invention is the use of small amounts of water-insoluble plasticizers in the polymerization formulation, which allows for a reduction of up to about 50% or more in the amount of emulsifier or soap required in the polymerization formulation. be. Examples of water-insoluble plasticizers include dioctyl adipate, epoxidized soybean oil, dioctyl phthalate, dioctyl azelate, dicapryl adipate, diisodecyl phthalate, isopropyl myristate, isopropyl palmitate, n-heptyl-n-nonyl adipate, and the like. . The amount of plasticizer used is small and generally ranges from 0.1% to 1.0% by weight relative to the weight of the monomers to be polymerized. The plasticizer is loaded into the premix in the conventional manner without the need for special or extraordinary techniques prior to homogenization with the other ingredients. When producing vinyl dispersion resins, such as when aqueous emulsion polymerization techniques are used, the aqueous reaction medium contains one or more emulsifiers or emulsifiers, such as salts of long chain fatty acids and long straight chain unsaturated alcohols. Including systems. Alkali metal or ammonium salts of long linear unsaturated fatty acids may be used as emulsifiers or Used as part of an emulsifier system. The unsaturated fatty acids mentioned may be either natural or synthetic and contain from 8 to 20 carbon atoms. Examples of such acids include lauric acid, myristic acid, palmitic acid, marganic acid, stearic acid, beef tallow, coconut oil, and the like. Excellent results are also obtained when anionic emulsifiers are used, such as alkali metal or ammonium salts of sulfuric acid of alcohols having 8 to 18 carbon atoms. Examples of such emulsifiers include alkali metal and ammonium salts of sulfonated petroleum and paraffinic oils, such as sodium lauryl sulfate, ethanolamine lauryl sulfate, ethylamine lauryl sulfate; dodecane-1-sulfonic acid and octadiene-1-sulfonic acid. Sodium salts of hydrocarbon sulfonic acids such as; sodium salts of α-olefin sulfonic acid; aralkylsulfonates such as sodium isopropylbenzenesulfonate, sodium dodecylbenzenesulfonate, sodium isobutylnaphthalenesulfonate, etc.; alkali metal and Ammonium salts, etc.; alkali metal and ammonium salts of sulfonic acid dicarboxylic acid esters such as sodium dioctyl sulfosuccinate, disodium-n-octadecyl sulfosuccinate, etc.; alkali metal and ammonium salts of free acids such as complex organic mono- and di-phosphate esters. Mention may be made of metal and ammonium salts. Nonionic emulsifiers such as octyl or nonylphenyl polyethoxyethanol may also be used.
Vinyl polymer latexes with excellent stability are obtained when using alkali metal and ammonium salts of aromatic sulfonic acids, aralkyl sulfonates and long chain sulfonates. When using plasticizers according to the invention, emulsifiers are used in amounts ranging from 0.6% to 1.2% by weight, based on the weight of the monomers to be polymerized. When more than one emulsifier is used in the system, the combined weights are in the same range.
In addition to the compounds listed above, 8-24 are often used to obtain some desirable vinyl dispersion resin properties.
Long straight chain unsaturated alcohols containing carbon atoms are used in the emulsifier system. Addition of alcohol to the system increases the colloidal stability of the polymerization system. Furthermore, the presence of alcohol reduces the amount of polymer build-up and coagulum. Examples of such alcohols are actanol, nonanol, decanol,
Undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, heneicosanol, docosanol, tricosanol,
Examples include tetracosanol. Mixtures of alcohols may also be used. For example, 12 carbon alcohols and 18 carbon alcohols are used. Also, lower carbon content alcohols can be used in combination with longer chain length alcohols. For example, a mixture of dodecanol and octadecanol. Additionally, ethoxylated alcohols can be used, such as mixtures of ethoxylated linear primary alcohols containing 12 to 15 carbon atoms. US Pat. No. 4,076,920, issued February 28, 1978, shows the use of the alcohols with emulsifier compounds in emulsifier systems. However, in said patent, the emulsifier is restricted to ammonium salts of fatty acids, and the ratio of alcohol to fatty acid is 1.0, but preferably the ratio is greater than 1.0. On the other hand, when alcohol is used in the present invention, the ratio of alcohol to emulsifier is less than 1.0 and preferably ranges from about 0.15 to about 0.75. In the emulsion polymerization method of the present invention, the polymerization method is expensive.
It is done at PH. The method is carried out at a pH ranging from 2.0 to 10.5. If the PH is too high, too much alkali is required, and if the PH is too low, for example below 5.0, coagulation will increase. The amount of alkali required to properly adjust and maintain a suitable PH depends somewhat on the particular emulsifier system used in the reaction mixture. As in all vinyl polymerization processes, the instantaneous proceeding is guided by the presence of a compound capable of initiating the polymerization reaction. Free radical generating initiators commonly used to polymerize olefinically unsaturated monomers are satisfactory for use in the present process. However, it is most important that the initiator is insoluble in water. Useful initiators or catalysts include, for example, lauryl peroxide, isopropyl peroxydicarbonate, bis(4-tert-butylcyclohexyl)peroxydicarbonate,
Di(2-ethylhexyl) peroxydicarbonate, diisononanoyl peroxide, benzoyl peroxide, t-butyl hydroperoxide, t-butyl peroxypivalate, cumene hydroperoxide, t-butyl diperphthalate, pelargo Nil peroxide, 1-
Various peroxides such as hydroxycyclohexyl hydroperoxide, t-butylperoxyneodecanoate, etc.; azo compounds such as azodiisobutyronitrile, dimethylazodiisobutyrate, etc. The amount of initiator used is generally relative to the weight of monomers to be polymerized.
In the range 0.01-0.5% by weight, preferably about
Between 0.015% and 0.15% by weight. The initiator is fully loaded at the beginning of the polymerization. When the initiator is first charged, it is added to the monomer premix along with the other components of the reaction mixture.
This is especially the case when the premix is homogenized before charging to the reactor. However, when the initiator is added to the premix and then homogenized, it is necessary that the temperature throughout the premixing and homogenization steps be kept below the minimum reactivity temperature of the particular initiator used. For example, when preparing a premix of vinyl chloride, water, plasticizer and suitable emulsifier and then adding isopropyl peroxydicarbonate into it, the temperature is maintained at 20°C during the mixing stage and during the subsequent homogenization stage. Ru. After charging the homogenized mixture to the polymerization reactor, the temperature is raised to the temperature at which the reaction takes place. An important aspect of the invention is that the monomer premixes are thoroughly mixed prior to input to the reactor. Mixing is usually done in separate containers or premix tanks. When the catalyst is added at the beginning of the reaction, it is the last component added to the premix. Also, the catalyst used is not soluble in water, so it should be added to the premix in a suitable solvent that also ensures emulsification in the premix and distribution therein. It goes without saying that any such solvent should be inert to the reaction components and reaction conditions. For example, when using isopropyl peroxydicarbonate as a catalyst or initiator, it is dissolved in hexane and then added to the premix. After the monomer premix, ie the reaction premix, is thoroughly mixed, it is then homogenized before entering the polymerization stage or reactor. It is of utmost importance in this invention that all of the components of the polymerization recipe are homogenized together at the same time. Several convenient means of homogenization can be used. Manton-Gaulin homogenizers, either one-stage or two-stage, have been found to be convenient devices for homogenizing the premixes contemplated by the present invention. The premix leaves the homogenizer directly into a reaction vessel preferably containing an inert atmosphere such as nitrogen. The homogenization step is important as it ensures proper particle size of the polymer in the final latex. Particle sizes in the range of about 0.1 microns to about 10.0 microns are preferred, although most particles are about 2 microns in size. When the particles of the polymer are of suitable size, it ensures good properties in the plastisol produced therefrom. The temperature at which the polymerization reaction is carried out is important because the intrinsic viscosity (IV) of the plastisol prepared with the vinyl dispersion resin thus produced is a direct function of the reaction temperature. That is, the higher the temperature, the lower the IV. The end use of the vinyl dispersion resin produced will therefore typically dictate the polymerization reaction temperature.
For example, when producing vinyl dispersion resins for coating or casting flexible films, lower reaction temperatures are desirable for many coating applications.
Used to reach IV. It has been found that polymerization temperatures in the range of 30°C to 70°C are satisfactory for end uses to which vinyl dispersion resins are particularly applied. However, preferably temperatures in the range of about 40°C to about 55°C are used. It is noted that, in general, increasing reaction temperature increases polymer build-up on the interior surfaces of the reactor. However, when practicing the present invention, polymer build-up is substantially reduced. This is due to a large reduction in the amount of emulsifier used, which on the one hand is due to the lower amount of plasticizer present in the reaction mixture. The small amount of polymer build-up that forms can be removed by rinsing or hosing off with water rather than a hard shell, and by opening the reactor if a suitable spray nozzle is fitted to the reactor. It can be easily removed without. After the polymerization reaction is completed, the vinyl dispersion resin is separated from the latex in powder form by spray drying. That is, a fine spray of polymer latex is injected into a heated air chamber, thereby removing water and recovering the dried resin in powder form. Plastisol is prepared by uniformly blending or intimately mixing 100 parts by weight of a dispersion resin in powder form and about 30 parts by weight to about 100 parts by weight of one or more plasticizers by a conventional method. The vinyl dispersion resin of the present invention is also produced by the above method. Plasticizers useful for this purpose may be mentioned as alkyl and alkoxyalkyl esters of dicarboxylic acids or esters of polyhydric alcohols and monobasic acids. Examples of such substances include dibutyl phthalate, dioctyl phthalate, dibutyl sebacate, dinonyl phthalate, di(2-ethylhexyl) phthalate, di(2-ethylhexyl) adipate,
Examples include dilauryl phthalate, dimethyltetra-chlorophthalate, butylphthalylbutyl glycolate, glyceryl stearate, and the like.
Preferred plasticizers are aliphatic alcohols having 4 to 20 carbon atoms and liquid diesters of dibasic carboxylic acids having 6 to 14 carbon atoms. Plastisols made from vinyl dispersion resins should have a desirable yield value. Yield value is simply defined as the resistance to flow and is generally determined numerically from viscosity measurements using known standard techniques. Typically such values are arrived at by calculation from viscosity measurements using a Bruckfield type RVF Viscometer according to ASTM method D1824-61T. The yield value is determined from viscosity measurements of the plastisol by varying the rpm (revolutions per minute) after initial preparation and after a period of aging. Viscosity is measured in centipoise (cps) at a temperature of 23°C. In the special case described below, the viscosity measurements are at 2rpm and 20rpm.
are measured and expressed as V ₂ and V ₂₀ , respectively. It will be appreciated that the following specific examples are provided to further explain the invention, but are merely illustrative and not intended to be limiting. All parts and percentages in the examples are by weight unless otherwise indicated. EXAMPLE In this example, several experiments were performed using various plasticizers as shown in the table below. In the experiment, the following prescription was used. The amount of plasticizer is indicated in the table. Parts Vinyl chloride 100 Water (ion exchange) 140 α-olefin sulfonate 0.9 Alcohol (C ₁₂ +C ₁₈ ) 0.25 Diisononanoyl peroxide 0.05 Di-(2-ethyl-hexyl) peroxydicarbonate 0.04 All substances including plasticizers The ingredients were loaded into the premix tank and the vinyl chloride was finally loaded after the tank was placed under vacuum. The mixture was stirred and stirred for 15 minutes at a temperature of 20°C. Then premix in two stages at a temperature of 20℃.
It was homogenized with a Manton-Gaulin model L-100 homogenizer and transferred to the polymerization reactor. The first stage of the homogenizer is performed at 700 psig, and the second stage is
It was 600 psig. The reactor was evacuated prior to addition of the homogenized premix. The reaction was carried out by heating the reactor to a reaction temperature of 45° C. and stirring until completion. The polymer latex or slurry was removed from the reactor and spray dried to recover the dry PVC or resin. Plastisols were made from the polymer for each experiment for evaluation. The plastisol formulation used was in each case as follows. Part PVC (polyvinyl chloride) 100 Dioctyl phthalate 57 Epoxidized soybean oil 3 Ba-Zn stabilizer 2 Pertinent data regarding the polymerization and plastisol properties are given in the following table.

【table】

[Table] (a) Using 0.9 parts of sodium lauryl sulfate and NaOH instead of α-olefin sulfonate (b) Using 0.26 parts of each of the two catalysts (peroxide and peroxydicarbonate) From the above data Although most of the properties are compared to the previous dispersion resins, it can be seen that the amount of emulsifier can be greatly reduced. Furthermore, thermal stability is increased by use of the present invention. Example In this example, three additional experiments were performed to demonstrate improved resin properties. The same procedure as shown in the examples was used in these experiments. The formulation and properties are shown in the table below.

【table】

[Table] From the above results, the improvement in properties is particularly evident in the Bruckfield viscosity and Sabers fluidity. The improvement in clarity and gel temperature is particularly evident in Run No. 9. EXAMPLE Two experiments were performed in this example, one using the present invention and the other using prior art as shown in US Pat. No. 4,113,687. The purpose of these experiments is to demonstrate the improved foam properties obtained according to the invention. Its formulation, polymerization conditions and properties are shown in the following table.

【table】

[Table] Reaction temperature 55°C 50°C Reaction time (hours) 13 % conversion 94 Plastisols were prepared with resins to determine Bruckfield viscosity, density, cell structure grade, and color tone grade. The ingredients were mixed in the usual manner using the following plastisol formulation.

【table】 The properties of plastisol are given in the following table.

Table: The above values point out an increase in the molding properties of the plastisols of the invention relative to those of the prior art.
The foam's cellular structure means that the air bubbles within it are smaller and have a more uniform distribution.

Table Once again the data shows comparable improved properties. The many benefits of the present invention are readily apparent from the foregoing description and specific examples. The vinyl dispersion resins produced as demonstrated herein have improved Bruckfield viscosity, saver fluidity, good clarity, as well as gel temperature and defoaming. A further important benefit of the present invention is improved plastisol foam properties. Also, a lower amount of emulsifier thus provides a more economical and commercial process and provides considerable savings in manufacturing costs.
Another important factor of the present invention is the reduction in polymer build-up in the reactor which not only lowers cost but also results in better quality produced with increased yield. Many other benefits of the invention will be apparent to those skilled in the art. Although the invention has been described by way of specific examples thereof,
Certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of this invention, which may be limited only by the fair scope of the appended claims.