KR810001468B1 - Emulsion poly merization of polyvinyl chloride using mixedemulsifier system ina single step - Google Patents

Abstract

A 1-step process for the emulsion polymn. of vinyl chloride utilized an aq. emulsion system comprising (a) a C12-18 straight chain alkyl or alkenyl phosphate surfactant and (b) a C12-20 straight chain alkyl or alkenyl alc. and (or) a straight chain satd. hydrocarbon with>18 C atoms. Thus, a PVC plastisol was obtained in the presence of a Na lauryl phosphate-stearyl alc. mixed emulsifier.

Description

Emulsion Polymerization of Vinyl Chloride Using Mixed Emulsifiers

The present invention relates to an emulsion polymerization method of vinyl chloride using a mixed emulsion.

In the emulsion polymerization of vinyl chloride, the use of conventional straight chain surfactants (for example, sodium lauryl sulfate) is not carefully controlled by the incremental supply method. Otherwise, it results in the formation of very small polymer particles. A general method for obtaining larger particles of polyvinyl chloride is, in one step, forming seed seed particles of the polymer in the initial polymerization step, followed by two step polymerization or seed growth. Step 가 is performed. The recently published US patents on this seed growth method are as follows. That is, U.S. Pat. have. A scientific document by J. Ugelstad et al. (Polymer sci, Symposium 42, pp. 473-485, 1973) proposed the effect of a mixed emulsifier of a conventional surfactant and an alcohol only in the second step of the process.

In addition to the foregoing prior art, the use of various alcohols such as stearyl alcohol as a component in the polymerization medium has been studied by other researchers. For example, in U.S. Pat.Nos. 3,324,097 (patented by G. A. Pierce) and 3,654,248 (patented by Ida et al.), Vinyl chloride homogenized in the presence of an oil soluble catalyst in a suspension polymerization process. The polymerization method for polymerizing is described. When this method is used, a mixture of emulsified and suspension polymerized polyvinyl chloride particles is formed. In addition, a description of the effect of the emulsifier of the surfactant and the alcohol in the polymerization of styrene (by a one-step process) has been published in the following technical documents. Die Makromolekurare chemie (J. Ugelstad et al.), Vol. 175, pp. 507-521 (1974); Polymer Science, Polymer Letters by J. Ugelstad , Polymer letters), Vol. 11, pp. 503-513 (1973); and by A.M.Azad et al. Seed. Acs Polymer Reprints, Vol. 16, No. 1, pp. 131-142 (April 4, 1975).

In British Patent No. 1,142,425 (patented by Starwoo Chemical Company), alkylphosphite surfactants have been proposed as the main emulsifier in the emulsion polymerization of vinyl chloride by the seed growth method. In US Pat. No. 2,843,576 (patented by J. H. Dunn et al.), In order to obtain products with highly porous batches in the form of aggregates, they are combined with monomer-soluble initiators to emulsify the emulsion polymerization process. As proposed.

However, until now it has not been found that the polymerization of vinyl chloride monomer can be achieved in a one step process by using an aqueous mixed emulsion containing a water soluble initiator and a straight alkyl or alkenyl phosphite surfactant.

The present invention relates to (1) C ₁₂ -C ₁₈ straight chain alkyl or alkenyl phosphate surface active agents such as sodium lauryl phosphate and (2) cetyl alcohol, oleyl alcohol, stearyl alcohol and iacosanol and / or 18 or more carbon contents A method of emulsion polymerization in a one step process using an aqueous mixed emulsion of C ₁₂ -C ₂₀ straight alkyl or alkenyl alcohol, such as straight chain saturated hydrocarbons, wherein the product is useful as a plastisol or organosol resin. Do.

This polymerization medium contains an effective amount of vinyl chloride monomer (or comonomer), a water soluble initiator, a mixed emulsion and, if desired, a buffer for the polymerization of the desired vinyl chloride monomer.

The vinyl chloride monomer contains at least 50%, preferably 85%, by weight of the total monomer component, preferably a sole monomer. However, copolymers can also be advantageously prepared according to the invention. For example, copolymerizable mixtures containing vinyl saline and up to 49% vinyl acetate but preferably in the range 5-10% vinyl acetate can be used. Monomers copolymerizable with vinyl chloride usable according to the present invention include vinyl esters of other alkanoic acid such as vinyl propionate and vinyl butyrate; Vinylidene halides such as vinylidene chloride; Vinyl esters of aromatic acids such as vinyl benzoate; Esters of alkanes (eg, esters of unsaturated monocarboxylic acids such as methyl, acrylate, 2-ethyl hexyl acrylate and corresponding esters of methacrylic acid); And esters of alpha, beta-ethylenically unsaturated dicarboxylic acids (e.g., pentyl esters of methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, allylmetall and maleic acid itaconic acid fumaric acid). Amides such as acrylamide and methacrylamide and nitriles such as acrylonitrile can also be used as appropriate. Vinylphosphonates such as bis (betachloroethyl) vinyl phosphonate can also be used. The ratio of water to monomer in the reaction medium can vary widely within the range of about 1.5-2.5: 1, with a ratio of about 1.7-2.0: 1 being preferred and this is a representative ratio.

The initiator or catalyst used in the present invention may be any well-known water-soluble initiator used in vinyl chloride monomer emulsion polymerization. Oil-soluble catalysts are not recommended, which leads to a suspension and emulsion particle mixture, to a mixed emulsifier, to a mixture of emulsifiers, whether the emulsifier is homogenized before use or used as a pre-homogenized adduct. This is because it shows a binodal or polydisperse particle size distribution. Free radical soluble initiators such as ammonium persulfate, sodium perborate, potassium persulfate, sodium persulfate, and potassium percarbonate, which are peroxygen type compounds, are examples of initiators that can be used. You can also use redox systems if you want. Representatives of such systems are hydrogen peroxide initiator / ascorbic acid activator combinations or potassium persulfate / ascorbic acid combinations. Combinations of persulfates and bisulfites, such as potassium persulfate and metajungsulfate, can also be used. The amount of initiator used should be such that the monomer polymerization in the reaction medium is effective, usually about 0.05% -1% of monomer weight, preferably about 0.075% -0.10% of initiator or redox system .

The mixed emulsion emulsifier systems of the present invention are characterized by (1) C ₁₂ -C ₁₈ straight alkyl or alkenyl phosphate surfactants, (2) C ₁₂ -C ₂₀ straight alkyl or alkenyl alcohols or saturated hydrocarbons larger than 18 carbon atom chains. Include.

C ₁₂ -C ₁₈ straight chain phosphate surfactants useful in carrying out the invention

Wherein R is a straight-chain alkyl or alkenyl grouping containing 12-18 carbon atoms each, M is ammonium or an alkali metal ion, and X is one or two. Representative R grooves include lauryl, tridecyl and octadecyl. Some suitable M groupings include ammonium, lithium, sodium and potassium. One surface active agent preferred for this class of compound is sodium lauryl phosphate.

C ₁₂ -C ₂₀ linear alkyl or alkenyl alcohols used in the mixed emulsion emulsifier system of the present invention include cetyl alcohol, oleyl alcohol, stearyl alcohol and icosanol. A typical saturated hydrocarbon with chains larger than 18 carbon atoms is icosane. Any mixture of the former second component of the mixed emulsifier can be used.

The amount of such emulsifier system used should be sufficient to maintain a stable emulsion in the reaction situation. Use of lesser amounts than described here will result in condensation of the latex, and use of higher amounts will result in contamination of the unwanted product with nothing. The weight ratio of surfactant to alcohol in the mixture is in the range of about 0.8: 1 to 1: 4, with about 0.8: 1 to 1: 2 being preferred to make the product having the desired physical properties in the present invention. The amount of mixed emulsification for the vinyl chloride monomer (in the presence of a copolymerizable monomer) is from about 0.7% to about 3% by weight of the polymerized monomer, but is preferably from about 0.8% to about 2%.

It is highly desirable to use a suitable buffer such as borax to maintain the reaction medium at a pH of about 5-8, more preferably at about 6-7.5, which usually results in larger polydispersities than can be obtained with surfactant systems alone. This is because the production of resin particles will be guaranteed.

If desired, mixtures of phosphate surfactants and alcohols or hydrocarbons can be homogenized prior to use in the polymerization to produce a renewable product having a more homogenized particle size distribution. In this method, the two components of the mixed emulsifier are homogenized until they appear to be a homogenized mixture by stirring into a suitable device when in liquid form. If this mixture is solid at one or both of its components at room temperature, after the component has been heated above its melting point, the reactants of the monomers and the initiator can be added. The polymerization process of the present invention is accomplished by heating the reaction mixture at about 45-70 ° C. for about 3-5 hours. This invention is demonstrated by the following Example.

Example 1

This example illustrates the preparation of a mixed emulsifier used in the polymerization process of the present invention.

The following ingredients are mixed and heated to 70 ° C. to make sodium lauryl phosphate salt, using lauryl phosphate (3 g of this phosphate requires 4.5 10% NaOH to adjust to pH8). It was.

In a solution consisting of these, a series of emulsifiers prepared by mixing stearyl alcohol / sodium lauryl phosphate to be used in later examples are prepared.

Example 2

This example illustrates the use of sodium laurylfospace / stearyl alcohol emulsifier (hereinafter abbreviated as SLP / SA) in polymerizing a vinyl chloride monomer at once. The reaction was carried out for 4 hours at a temperature of 54 ° C. in the vessel, respectively. The following table records the reactants used and the results obtained.

Progress number

(week)

The number in parentheses is the weight ratio of sodium lauryl phosphate to stearyl alcohol.

1) The amount of dry condensate is based on the weight of the monitor charge. Small amounts are preferred because the coagulum has an adverse effect on commercial operation.

2) Physical stability is measured by stirring the resulting latex with a Hamilton Bitch laboratory mixer, which was rotated at low speed. The time it takes for the product to condense in the mixer is measured visually. This test is a measure of the amount of time it takes to set the latex, and more time is desirable. In a commercial production environment, condensation has an adverse effect since latex is simply processed using a pump.

Claims (1)

As described above in the text, in the emulsion polymerization method for forming a vinyl chloride polymer formed by heating a vinyl chloride-containing monomer in the presence of a water-soluble initiator and an emulsifier, (1) at least one C ₁₂ -C of the following structural formula _In one step, by using a mixture of ₁₈ straight chain phosphate surfactants and (2) C ₁₂ -C ₂₀ straight chain alkyl or alkenyl alcohols or saturated hydrocarbons having at least one chain larger than 18 carbon atoms, Emulsion polymerization method of vinyl chloride using a mixed emulsifier formed by forming a polymer.

Wherein R is a straight chain alkyl or alkenyl grouping containing about 12-18 carbon atoms, M is ammonium or an alkali metal ion, and X is 1 or 2.