JP3177894B2 - Extrudable polymer composition - Google Patents

Description

The present invention relates to a heat-sensitive plastic having reduced heat sensitivity and a method for producing the same.

Vinylidene chloride interpolymers are well known in the prior art. These polymers are also well known to be thermosensitive, which when exposed to the desired processing temperature,
These polymers are prone to thermal decomposition, producing, for example, carbonaceous material contamination, discoloration, or hydrogen chloride.

In the past, polymer compositions consisting of vinylidene chloride interpolymers have been extruded directly from the form from which they were collected. For transport and handling advantages, it is desirable to form these polymer compositions into pellets before final extrusion. As the demand for pellets increases, so does the demand for pellets that can withstand the many processing conditions experienced by powdered resins.

Although pellets of a polymer composition comprising a vinylidene chloride interpolymer may be in an advantageous form to construct an article therefrom, pellets of these polymer compositions are particularly difficult to extrude. The formation of pellets requires exposing the thermoplastic composition to heat before the conventional process of extruding the polymer composition into an article. It is believed that this additional thermal history makes the vinylidene chloride interpolymer in pellet form more thermally unstable than in the powder form. Therefore, additives that improve the thermal stability of polymer compositions comprising vinylidene chloride interpolymer in powder form do not necessarily improve the thermal stability of these polymer compositions in pellet form.

Extrusion is possible satisfactorily in a relatively short period of time, but attempts to extrude vinylidene chloride interpolymer pellets for an extended period of time with certain extruders have also resulted in the heat sensitivity of the vinylidene chloride interpolymer, resulting in undesirable amounts of carbonaceous material. It has been shown to be unsatisfactory due to material contamination, increased discoloration or large amounts of hydrogen chloride in the extrudate.

Has less carbonaceous material contamination, less discoloration or less hydrogen chloride generation than the vinylidene chloride interpolymer alone, and less carbonaceous material contamination, less discoloration or less than the extrudate formed from the vinylidene chloride interpolymer alone It is desirable to produce a polymer composition having the evolution of hydrogen chloride. It is this goal that the present invention is concerned with.

The process of the present invention is a process for producing a polymer composition, the process steps comprising: (A) 60-99% by weight of vinylidene chloride monomer and 40% by weight.
To form a polymerizable monomer mixture having a monomer phase comprising at least one ethylenically unsaturated comonomer copolymerizable therewith and an aqueous phase in an amount of from about 1% by weight
Is based on the weight of the monomer mixture), (B) polymerizing the polymerizable mixture to form a polymer slurry having an aqueous phase and a polymer phase, and (C) drying the slurry to obtain a polymer. Forming a composition, after the start of step (A) and before the completion of step (C), adding an amount of at least one salt of a non-alkene weak acid to a polymerizable mixture or polymer slurry. In addition to any of the above, the pH of the aqueous phase of the polymer slurry is adjusted to an amount effective to improve the color stability of the polymer composition and from 0.01 to 5% by weight of the combined amount of monomers at the time of addition. Within the range is characterized by maintaining the polymer composition at a value effective to provide a reaction product.

The invention, in a second aspect, is a polymer composition comprising a vinylidene chloride interpolymer in an amount of at least 80% by weight, based on the total weight of the composition, wherein the interpolymer is in an amount of 60-99% by weight. Vinylidene chloride monomer and 40
Formed from a monomer mixture consisting of at least one ethylenically unsaturated comonomer copolymerizable therewith in an amount of １1% by weight, said weight% being based on the weight of the monomer mixture, The composition may also comprise from 0.01 to 5% by weight (based on the total weight of the composition) of a non-alkene weak acid salt reaction product in an amount effective to provide improved thermal stability to the polymer composition. It is characterized by including.

In a third aspect, the invention relates to the use of a polymer composition as described above for producing a melt extruded article.

The present invention relates to polymer compositions having "improved extrudability" (as defined below). The polymer or plastic composition comprises a vinylidene chloride interpolymer and the reaction product of a non-alkene weak acid to form the polymer or plastic composition. By "polymer or plastic composition" is meant to include, along with other additives, the reaction product of a vinylidene chloride interpolymer and a non-alkene weak acid. The amount of vinylidene chloride polymer is at least 80% by weight, based on the weight of the total composition. It is preferably at least 90% by weight.

For the purposes of the present invention, the term "improved extrudability" refers to the fact that when exposed to the desired high processing temperature, the polymer composition has a lower heat sensitivity, resulting in reduced extrudate It means having an amount of carbonaceous material contamination, less discoloration or less evolution of hydrogen chloride.

By "extruded", during processing methods such as casting, blowing, extrusion molding, injection molding, blow molding, co-extrusion, lamination or calendering, become partially or completely molten when exposed to high temperatures All compositions are meant.

The term "vinylidene chloride interpolymer" includes vinylidene chloride homopolymers, copolymers, terpolymers, and the like. Polymer compositions suitable for use in the present invention are those prepared from a monomer mixture consisting of a predetermined amount of a vinylidene chloride monomer and also a predetermined amount of an ethylenically unsaturated comonomer copolymerizable therewith. It is a vinylidene chloride interpolymer.

To make the monomer phase, this phase consists of a mixture containing almost all the monomers to be polymerized. An effective amount of the polymerized vinylidene chloride monomer is generally in the range of 60-99% by weight of the interpolymer, with the preferred range being that of the ethylenically unsaturated comonomer copolymerized therewith as is well known to those skilled in the art. Dependent.

The ethylenically unsaturated comonomer is kept below an amount effective to destroy the semi-crystalline nature of the interpolymer.
By "semi-crystalline", it means that the interpolymer has about 5
Has a crystallinity of about 95%. The value of crystallinity depends on the measurement technique, and as used herein, crystallinity is determined by commonly used density methods. For example,
Polyvinylidene Chloride, Volume 5, Go-rdon and Bre
See paper by RAWessling in Chapter 6 of ach Science Publishers, New York (1977).

The ethylenically unsaturated comonomer copolymerizable with the vinylidene chloride monomer present in the monomer mixture is in an amount of 1 to 40% by weight, said weight% being based on the weight of the total monomer mixture .

Suitable ethylenically unsaturated comonomers copolymerizable with the vinylidene chloride monomer include vinyl chloride, alkyl acrylates, alkyl methacrylates, acrylic acid, methacrylic acid, itaconic acid, acrylonitrile and methacrylonitrile. Alkyl acrylates and alkyl methacrylates are generally chosen to have from 1 to 8 carbon atoms per alkyl group. Preferably, the alkyl acrylate and the alkyl methacrylate are present in an amount of 1 per alkyl group.
It is chosen to have up to 4 carbon atoms. Alkyl acrylate and alkyl methacrylate are most preferably selected from the group consisting of methyl acrylate, ethyl acrylate and methyl methacrylate.

When the ethylenically unsaturated comonomer used is vinyl chloride, the vinyl chloride is preferably an interpolymer
Vinylidene chloride is present in an amount of 70-95% by weight of the interpolymer, and more preferably vinyl chloride is present in an amount of about 25% to about 10% by weight of the interpolymer.
Vinylidene chloride is present in the interpolymer
It will be present in an amount of 75-90% by weight.

When the ethylenically unsaturated comonomer used is an alkyl acrylate, the alkyl acrylate is preferably present in an amount of 30 to 2% by weight of the interpolymer and vinylidene chloride is present in an amount of 98 to 70% by weight of the interpolymer. Present in an amount, preferably vinyl acrylate, is 40 to 40% of the interpolymer.
The vinylidene chloride will be present in an amount of 6% by weight and the vinylidene chloride will be present in an amount of 94-60% by weight of the interpolymer.

A method for forming a vinylidene chloride interpolymer comprises:
It is well known in the prior art. The vinylidene chloride interpolymer is generally formed by an emulsion or suspension polymerization method. Examples of these methods are described in U.S. Pat.
8, 3007903, 3642743 and 3879359 and Polyvinyli-
dene Chloride, Volume 5, Gordon and Breach Science
RAWessl in Chapter 3 of Publishers, New York (1977)
ing.

In emulsion or suspension methods, the monomer phase is emulsified or suspended in the aqueous phase, preferably by the use of emulsifiers or suspending agents. An initiator and a surfactant capable of emulsifying or suspending the monomeric material in the aqueous phase are then added to the solution, and the polymerization of the monomer is allowed to proceed until its desired degree of conversion is obtained. The polymerization of the monomer material is usually performed by heating and stirring.

A relatively small amount of a water-soluble suspending or emulsifying agent is used as follows, and a significant proportion of the monomer is
Homogeneously mixed with at least about 0.01% by weight, preferably about 0.1-1% by weight of a water-soluble dispersant and 0.1-0.5% by weight of a monomer-soluble polymerization initiator (the weight% is based on the weight of the monomer) ).

Examples of the water-soluble suspending agent or emulsifier include an alkyl group having 1
A water-soluble alkyl or hydroxyalkyl cellulose ether containing from 2 to 2 carbon atoms and a hydroxyalkyl group containing from 2 to 4 carbon atoms. Although all viscosity grade cellulose ethers are used, it is preferred to use lower viscosity grades, for example 10-400 cps. Low viscosity grade methylcellulose and hydroxypropyl methylcellulose dissolve more readily in water than high viscosity grades. Grade of viscosity as used herein refers to the viscosity of a 2% aqueous solution of cellulose ether measured at 20 ° C. The process of the present invention produces the polymer in granular or bead form that can be easily isolated from the polymerization system by simple means such as filtration. Washing with water removes most of the remaining components of the dispersant and catalyst system.

Examples of initiators contemplated for use in the present invention include peroxides such as hydrogen peroxide, isopropyl peroxycarbonate, lauroyl peroxide or mixtures thereof.

The order of addition of the various components is not critical, but it is preferred to make a complete aqueous phase containing the initiator and emulsifier or suspending agent and then add to the monomer phase. To make the aqueous phase, it is found that it is most important, but not essential, to solubilize the emulsifier or suspending agent and then add the initiator. The amount of water used has little effect on the process, but it is preferred to operate in the range of 2 to 4 parts water per part monomer. When less water is used, there is insufficient heat transfer to carry away the heat of polymerization.

Except where noted herein, the polymerization conditions (eg, temperature and agitation) are those that are conveniently used for the polymerization of vinylidene chloride.

When the monomer is added to the aqueous phase (the phase of the monomer in water), the mixture is allowed to react in a substantial absence of oxygen for a time sufficient to effect the desired conversion of the monomer to polymer. , 25-85 ℃
Preferably, it is heated with stirring to a temperature between 45 and 60 ° C. Generally, the conversion of monomer to polymer is 80-99%, preferably 88-95%. After the polymerization is complete, the resulting suspension or emulsion slurry of the vinylidene chloride interpolymer is then vacuum stripped to form a monomer-free slurry. The slurry is then cooled, removed and dewatered, and the vinylidene chloride interpolymer is collected and dried. The resin is then hydrated to also form a polymer slurry. The method also includes the use of pre-filters, electro-filters and final dryers such as fluid energy dryers.

The salt of the non-alkene weak acid is selected to be soluble or partially soluble and has a composition that does not adversely affect the properties of the vinylidene chloride interpolymer. Non-alkenoic acid salts are
Dissociated by water, at least partially ionized and solvated,
Further, the structure has no -C = C- bond. `` Dissolved or partially dissolved '' means that the salt of the non-alkene weak acid is about 0.
Meaning has a solubility of greater than 1% by weight, preferably about 0.5% in the aqueous phase and most preferably about 1% by weight in the aqueous phase. Solubility is affected by temperature, pressure, pH and other components of the composition, and these factors are well known to those skilled in the art, and their effect on the present invention is:
It can be easily determined without undue experimentation.

The non-alkene weak acid is selected from the following acids or derivatives thereof. That is, boric acid, hexapolyphosphoric acid, hypophosphorous acid,
Orthophosphoric acid, pyrophosphoric acid, phosphorous acid, tetrapolyphosphoric acid, tripolyphosphoric acid, alkyl monocarboxylic acid, aryl monocarboxylic acid, alkyl polycarboxylic acid, aryl polycarboxylic acid, hydroxyalkyl monocarboxylic acid,
Hydroxyalkyl polycarboxylic acids.

Salts are alkali metals (Ad Ad. By F. Albert Cotton and G. Wilkinson, published by Interscience in 1962).
-Vanced Inorganic Chemistry "and the alkaline earth metals (Group IIA of the periodic table) found in the inner cover.

Generally preferred non-alkene weak acid salts are those wherein the following properties are those of the non-alkene weak acid to the vinylidene chloride interpolymer alone, the vinylidene chloride interpolymer in the formulated resin or the vinylidene chloride interpolymer in the extruded product: It is selected from the above list of usable ones based on whether it is adversely affected by the addition of the salt.

(1) The effect on the permeability of oxygen and gas is measured indirectly by differential scanning calorimetry to determine whether the glass transition temperature of the vinylidene chloride interpolymer changes, or as described, for example, in Modern Control, Inc. It is measured directly by using OX-TRAN ™ 1050, commercially available from

(2) The taste and odor properties are preliminarily determined by examining the composition of the non-alkene weak acid salt. One structure is
Under various conditions, sometimes the taste and odor properties of the vinylidene chloride interpolymer are adversely affected, as well as certain structures may under certain conditions, sometimes, the taste and odor properties of the vinylidene chloride interpolymer extrudate For example, esters hydrolyze to release free alcohol. Generally, sulfur and nitrogen are
Contains structures that are prone to stench and has similar by-products.
Moreover, the structure of the ketone or aldehyde tends to be detectable in smaller amounts by taste and odor.

(3) Color and carbonaceous material contamination can be achieved by extruding a 3/4 ″ Brabender tape extrusion at about 175 ° C. between a vinylidene chloride resin containing a salt of a non-alkene weak acid and a resin having no salt of a non-alkene weak acid. It can be measured by inspecting the extruded material after performing the comparative extrusion.

(4) Thermal stability can be measured by differential scanning calorimetry or thermogravimetric analysis to determine whether non-alkene weak acid salts promote the decomposition of vinylidene chloride interpolymer.

(5) Finally, certain structures are eliminated because of their toxicological properties and because they are unacceptable in certain food contact applications. These compounds are generally selected after review of regulations issued by government agencies.

Examples of salts of non-alkene inorganic weak acids include phosphates and derivatives thereof such as sodium phosphates (eg, tetrasodium pyrophosphate, sodium pyrophosphate, sodium orthophosphate, sodium polyphosphate), potassium phosphates (eg, potassium pyrophosphate) , Potassium orthophosphate, potassium polyphosphate); salts of weak non-alkene organic acids such as methyltrisodium pyrophosphate, sodium alkyl or aryl phosphate, phosphites and sulfates; salts of non-alkene carboxylic acids (eg, sodium oxalate, sodium citrate, Potassium acetate); salts of non-alkenedicarboxylic acids such as succinic acid (eg, sodium succinate, potassium succinate, lithium succinate); mixtures thereof and the like.

Non-alkene weak acid salts suitable for the purposes of the present invention are prepared by methods well known to those skilled in the art. For illustrative purposes only, the technology for producing tetrasodium pyrophosphate is based on The M
erck Index, 10th edition (1983).

As mentioned above, the salt of the non-alkene weak acid is added to the monomer before they are copolymerized into the vinylidene chloride interpolymer (ie, pre-added), or the salt of the non-alkene weak acid is added to the vinylidene chloride interpolymer. Added to the polymer dispersion (ie, polymer slurry addition). Moreover, the above two methods, pre-addition and polymer slurry addition, can be applied in combination. However, pre-addition is preferred because the non-alkene weak acid salt is more evenly dispersed in and throughout the resulting polymerization product.

According to the present invention, salts of non-alkene weak acids can be formed before dissociation into water or by an in-situ combination of a salt and an acid or acid derivative. At least one salt of the non-alkene weak acid is the monomer mixture or obtained in an amount effective to improve the color stability of the polymer composition in an amount that results in a reaction product in the polymer composition. The reactor is charged together with the polymer slurry. Generally, at least one salt of the non-alkene weak acid is
0.1 based on the weight of the monomer mixture or polymer slurry.
It is added in an amount of 001 to 10% by weight. The reaction product of the salt of the non-alkene weak acid is generally 0.01-5% by weight, preferably 0.05-3% by weight, most preferably 0.1-1% by weight, calculated as if all acidic protons were replaced by sodium ions. % Of the resulting dried polymer composition.

In other embodiments, the non-alkene weak acid or salt can be applied via polymer slurry addition. That is, the alkene carboxylic acid or salt is added to the polymer slurry continuously with the salt of the non-alkene weak acid.

The alkene carboxylic acid or salt is added in an amount of 0.001 to 10% by weight, such that the resulting polymer composition is an alkene carboxylic acid in an amount effective to provide improved color stability of the polymer composition. Includes acid or salt reaction products. The reaction product of the alkene carboxylic acid or salt is generally from 0.01 to 5
Wt% preferably 0.05-3 wt% most preferably 0.1-
It will be present in the resulting dried polymer composition in an amount of 1% by weight.

Examples of alkene carboxylic acids or salts will include acrylic acid, oleic acid, linoleic acid, linolenic acid and dicarboxylic acids such as fumaric acid and maleic acid and salts thereof. In a preferred embodiment, the mixture consists of a salt of a non-alkene weak acid such as tetrasodium pyrophosphate and an alkene carboxylic acid or salt such as maleic acid or a salt thereof.

Alkenecarboxylic acid salts suitable for the purposes of the present invention are prepared by methods well known to those skilled in the art. For illustration purposes only, the technology for producing maleic acid is based on The Merck In
dex, 10th edition (1983).

In general, "reaction products" means that related substances added together are not removed in their original form. For the purposes of the present invention, a "reaction product" in particular becomes a salt of a non-alkene weak acid and an alkene carboxylic acid or salt becomes hydrated and becomes either protonated or deprotonated, thereby changing its composition. About the phenomenon. As non-alkene weak acid salts dissolve in water, they hydrolyze to form various substances. Subsequent drying and reduction of the composition does not return to its original structure or composition.
Thus, the present invention differs from anhydrous blends of the components of the polymer composition in which no reaction product is formed.

The exact amount of the non-alkene weak acid salt initially added to dissolve in the aqueous phase of the monomer mixture or polymer slurry is determined by the pH of the aqueous phase of the monomer mixture or polymer slurry; PH will vary depending on the phase ratio of the monomer mixture, ie, the ratio of monomer to water, and the solubility of the salt of the non-alkene weak acid in the aqueous phase. Once the above parameters are selectively determined, one skilled in the art can determine the amount of salt required without undue experimentation.

While not wishing to be bound by theory, it is believed that the salt of the non-alkene weak acid acts as a hydrogen chloride scavenger, effectively reducing the amount of free hydrogen chloride in the polymer composition. Acid scavenging relates to the number of basic sites in a portion of the reaction product. Those skilled in the art
It will be understood that this is inversely proportional to the number of protons in that same part.

As is well known by those skilled in the art, the aqueous phase of the monomer mixture
The pH must be kept in the range of 3 to 12 during times when the pH varies inversely with the amount of time outside the above range. However, the inventor has found that in the practice of the present invention, the aqueous phase of the polymer slurry must also be kept within a selected range. If, after addition of the salt of a non-alkene weak acid, the pH of the aqueous phase of the polymer slurry is too high or too low, discoloration of the polymer composition occurs.

The pH of the slurry after polymerization is generally in the range of 2-5. Generally, the interpolymer will remain in the polymer slurry when it has an extreme pH above about 12 or below about 3 during a time when it varies inversely with the amount of time outside of the above range. Is done. The choice of a particular pH for the aqueous phase of the polymer slurry is determined by one of ordinary skill in the art without undue experimentation.

The pH of the slurry depends on a number of factors and can be determined by one skilled in the art without undue experimentation. Examples of factors are the salt of the non-alkene weak acid and optionally the alkene carboxylic acid or salt used; the salt of the non-alkene weak acid and optionally the alkene carboxylic acid or salt being added to the monomer mixture; Agents; including any water-soluble substances added to aid polymerization and dehydrochlorination of the polymer. For salts of non-alkene organic weak acids; salts of non-alkene carboxylic acids and salts of non-alkene dicarboxylic acids and mixtures thereof, the site of greatest basicity is reached at pH values more basic than pH 3-5, but phosphate and In that derivative, the site of greatest basicity is reached at pH values that are more basic than pH 5.

Polymer compositions generally include substantially all of the hydrolyzed salts, but the relative amounts of each salt will depend on the pH of either or both the monomer mixture and the slurry. For example, tetrasodium pyrophosphate will hydrolyze to form a pyrophosphate anion, monohydrogen pyrophosphate, dihydrogen pyrophosphate, trihydrogen pyrophosphate and tetrahydrogen pyrophosphate. Thus, the present invention differs from blending a dry powder and a vinylidene chloride interpolymer to form a homogeneous mixture because the composition of the powder does not change.

Once the above parameters are determined, those skilled in the art
The pH of the slurry can be adjusted to reduce the discoloration of the polymer composition as desired without undue experimentation.

Various additives can be incorporated into the polymer composition of the present invention. The type of additive and its amount will depend on a few factors. One factor is the intended use of the polymer composition. The second factor is the tolerance of the polymer composition to the additives. That is, how many additives can be added before the physical properties of the polymer composition are adversely affected by unacceptable levels. Other factors will be apparent to those skilled in the art of polymer preparation and compounding.

Additives that can be added to the polymer composition of the present invention are selected from the group consisting of plasticizers, heat stabilizers, light stabilizers, pigments, processing aids, lubricants and the like. Each of these additives is well known, and a few types of each are commercially available.

Blending the additives to form the polymer composition can be accomplished using anhydrous blending techniques as well as conventional melt processing. The additives may be blended simultaneously with the vinylidene chloride interpolymer or continuously blended with the vinylidene chloride interpolymer.

In using conventional processing equipment for thermosensitive polymers,
Three conditions must be met. Two interrelated conditions are processing time and processing temperature. In polymer melt processing, the processing time increases as the processing temperature increases.
It is generally accepted that undesirable consequences must be shortened to avoid degradation of the polymer, for example. Melt processing must be achieved below the temperature at which decomposition of the vinylidene chloride interpolymer becomes significant. The third condition is that sufficient mixing occurs during the melt processing to obtain a macroscopically uniform blend, ie, macroscopically solid, with a reasonable mixing time.

Examples of the melt processing equipment are a two-roll mill, a Brab
Includes ender mixers, Banbury mixers, single screw extruders, twin screw extruders, etc., which are configured for use with thermosensitive polymers. For example, Polyvinylidene Chloride, Volume 5, Gordon and B
reach Science Publishers, 11 in New York (1977)
See RAWessling in the chapter. The desired results are obtained when either a single screw or twin screw extruder is used to melt process the components of the polymer composition. When anhydrous blending, the components should be mixed to form a macroscopically homogeneous mixture. Suitable anhydrous blenders include Hobart mixers, Welex mixers, Hen-schel high density mixers and the like.

Methods for forming polymer compositions into pellets are well known to those skilled in the art. All methods by which the polymer composition can be formed into pellets are suitable for use in the present invention. For purposes herein, the term `` pellet '' refers to at least 0.8 mm, preferably at least 1.6 mm, most preferably at least 3.2 mm
The pellet suitably has a maximum cross-sectional area of at least 12.8 mm, preferably at least 9.6 mm, most preferably at least 6.4 mm. An example of a method of forming the polymer composition into pellets includes extruding the polymer composition through a strand die to form an extruded strand, and then cutting the extruded strand into pellets.

The polymer composition, either in powder or pellet form, can be made into any suitable end product, such as various films or other articles. As is well known to those skilled in the art, films and articles are constructed by conventional co-extrusion, such as feed block co-extrusion, multi-manifold die co-extrusion or a combination of the two; injection molding; co-injection molding; You. Articles formed therefrom include blown and cast monolayer and multilayer films; rigid and foamed sheets; tubes; pipes; rods; fibers and various profiles. Lamination techniques are particularly suitable for producing multi-ply sheets. As is well known to those skilled in the art, certain lamination techniques include fusing (ie, whereby the self-supporting laminates are bonded together by the application of heat and pressure); wet combination (ie, where two or more plies are wetted). Laminated using the applied tie coat adhesive, displaces the liquid and combines by the next pressure lamination in one continuous process); reactivation by heating (i.e. heating and re-heating the pre-coated adhesive) Activation causes the pre-coated film to combine with the other film and become bonded after the next pressure lamination).

Examples of articles include rigid containers used for the storage of foods, beverages, pharmaceuticals and other fresh foods. These containers have good mechanical properties as well as e.g. oxygen, carbon dioxide,
It must have low gas permeability for water vapor, odor or scent, hydrocarbons or pesticides. Thus, the multilayer sheet structure used in the packaging material is laminated on each side of the vinylidene chloride interpolymer barrier layer, typically with an adhesive layer used to promote adhesion between the barrier layer and the foreign material layer. It has an organic polymer skin layer.

The present invention is further described by the following examples. The examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. All parts and percentages are by weight unless otherwise specified.

Examples 1-8 Polymer compositions are formed from a monomer mixture by a suspension polymerization method. Approximately 9 in a 37.85 liter stirring polymerization tank
9000 g of a mixture consisting of 4% by weight of vinylidene chloride monomer and about 6% by weight of methyl acrylate are charged. To the mixture in the reaction vessel, 16500 g of demineralized water, 0.4 g of di-tert-butylmethylphenol; 42 g of t-butyl peroctoate, 8.5 g of tetrasodium pyrophosphate as a trace metal scavenger and a suspending agent Of hydroxypropyl methylcellulose ether is added. The pH of the monomer mixture is adjusted between about 4 and 10.

The reactor is sealed, purged with nitrogen and raised to a temperature of about 25 ° C. After the polymerization has started, the temperature is raised to 80 ° C and the polymerization is continued for about 16 hours.

About 45 g of tetrasodium pyrophosphate is added to the resulting polymer slurry. A polymer slurry of polymer material is about 2
It has a pH of ４4. The pH of the polymer slurry is adjusted to be in the range between about 3 and 12, and the pH value in certain examples is
It is shown in Table I. The pH is adjusted to acidic by adding hydrochloric acid, adjusted to basic by adding NaOH, and then maintained at various pH values as shown in Table I. The polymer composition comprises
Next, it is recovered from the polymer slurry and dried. When tetrasodium pyrophosphate is dissolved in water, it hydrolyzes to form pyrophosphate anions, monohydrogen pyrophosphate, dihydrogen pyrophosphate, trihydrogen pyrophosphate and tetrahydrogen pyrophosphate. In the polymer composition, the reaction product of tetrasodium pyrophosphate is calculated as tetrasodium pyrophosphate in parts per 100 parts of the vinylidene chloride interpolymer. Tetrasodium pyrophosphate added as a trace metal scavenger is not included in this calculation.

The polymer composition has a length to diameter ratio of 25/1 3 /
Extruded through a 4 ″ extruder.
The following set temperatures: (a) hopper temperature = 160 ° C,
(B) Melt zone temperature = 170 ° C and (c) Die temperature = 175 ° C. The blend is passed through a 3/4 "extruder die
Extruded on tape.

The polymer composition is extruded on an extrudate tape in a continuous process for about 20 minutes. As the resin degrades, it changes color, ie, turns brown. Decomposition of the extruded resin is determined by visual inspection of the extruded tape to determine its color. Color is quantitatively measured on a scale of 1 to 10 over a continuous range of discoloration, where 1 represents creamy white and 10 represents slightly dark brown.

 The results are shown in Table I.

As can be seen from the above table, the polymer composition is extruded into extruded tapes having excellent color, and optimal color is obtained when the pH of the aqueous phase is greater than about 6.

Example 9 The procedure of Example 5 is repeated with the following exceptions. The polymer composition is extruded a second time through a single strand die, passed through a water bath, and then pelletized. The strand die had an inner diameter of 0.32 cm. Pelletization was achieved using a Model 304, 15.24 cm strand cutter commercially available from Conair Incorporated. The pellets are extruded into extruded tape in a continuous process for about 20 minutes. The extruded tape of the extruded pellets showed good color. Table I Example PS ¹ TSPP ² pH ³ Color ⁴ 1 100 0.25 6.0 4.9 2 100 0.25 7.0 1.8 3 100 0.25 7.2 2.6 4 100 0.25 7.5 1.4 5 100 0.25 8.3 1.4 6 100 0.25 8.7 2.0 7 100 0.25 8.9 2.0 8 100 0.25 10.5 3.1 PS ¹ = polymer of monomer mixture in 100 parts polymer, polymerized from an initial monomer charge consisting of 94% by weight of vinylidene chloride monomer and 6% by weight of methyl acrylate slurry.

TSPP ² = parts of tetrasodium pyrophosphate per 100 parts of polymer added to the polymer slurry. Tetrasodium pyrophosphate is commercially available from Monsanto Chemical Company, pH ³ = pH of the aqueous phase of the polymer slurry after tetrasodium pyrophosphate has been added and adjusted.

Color ⁴ = by visual inspection.

Examples 10-11 The procedure of Examples 5 and 9 is repeated with the following exceptions. The monomer mixture consists of 80% by weight of vinylidene chloride and 20%.
Consists of weight percent vinyl chloride. The extrudate tape of the polymer composition showed good color.

Example 12 The procedure of Example 5 is repeated with the following exceptions. Instead of adding 45 g of tetrasodium pyrophosphate to the polymer slurry, 45 g of tetrasodium pyrophosphate is added to the monomer mixture. The pH of the aqueous phase of the monomer mixture is adjusted to about 6.5. After the polymerization, the pH of the polymer slurry is adjusted to the value indicated in Example 6. Next, the polymer slurry is cooled, removed, and dewatered. Extrudate tapes from the extruded polymer composition showed good color.

Example 13 The procedure of Example 12 is repeated with the following exceptions. The polymer composition is extruded a second time from a single strand die and is then pelletized through a water bath. The strand die had an inner diameter of 0.32 cm. Pelletizing Co
Models 304 and 15.commercially available from nair Incorporated.
Achieved using a 24 cm strand cutter. The extruded tape of the extruded pellets showed good color.

Examples 14-15 The procedure of Examples 12-13 is repeated with the following exceptions. The monomer mixture consists of 80% by weight of vinylidene chloride and 20%.
Consists of weight percent vinyl chloride. The extrudate tape of the polymer composition showed good color.

Examples 16-19 The procedure of Example 5 is repeated with the following exceptions. Instead of adding 45 g tetrasodium pyrophosphate to the polymer slurry, 27 g orthophosphoric acid is added to the polymer slurry. Orthophosphoric acid is available from Fisher Scientific Co-mpany
It is commercially available from.

After the addition, the pH of the polymer slurry is adjusted with sodium hydroxide to the values shown in Table II.

When orthophosphoric acid dissolves in water, it hydrolyzes to form dihydrogen phosphate, monohydrogen phosphate and orthophosphate anions. In the polymer composition, the reaction product of orthophosphoric acid is trisodium orthophosphate as vinylidene chloride interpolymer 100
Calculated in parts per copy.

The results of Examples 16 to 19 are shown in Table II. Table II Example PS ¹ OPA ² pH ³ Color ⁴ 16 100 0.25 5.4 7.5 17 100 0.25 7.2 5.0 18 100 0.25 10.0 2.3 19 100 0.25 12.0 4.9 PS ¹ = 94% by weight of vinylidene chloride monomer and 6% by weight of acrylic Polymer slurry of a monomer mixture in 100 parts of polymer, polymerized from an initial monomer charge of methyl acid.

OPA ² = orthophosphoric acid, calculated as trisodium phosphate, per 100 parts of polymer in polymer slurry.
Orthophosphoric acid and sodium hydroxide are available from Fi-sher Scie
Commercially available from the ntific Company.

pH ³ = pH of the aqueous phase of the polymer slurry after adding orthophosphoric acid and adjusting to basic with NaOH.

Color ⁴ = by visual inspection.

As can be seen from the above table, the polymer composition can be extruded into extrudate tapes having excellent color, with optimal colors being obtained in a pH range of about 7 to about 12.

Example 20 The procedure of Example 18 is repeated with the following exceptions. The polymer composition is extruded a second time through a single strand die, passed through a water bath, and then pelletized. The strand die had an inner diameter of 0.32 cm. Pelletization was achieved using a Model 304, 15.24 cm strand cutter commercially available from Conair Incorporated. The pellets are extruded into extruded tape in a continuous process for about 20 minutes. The extruded tape of the extruded pellets showed good color.

Examples 21-22 The procedure of Examples 18-20 is repeated with the following exceptions. The monomer mixture consists of 80% by weight of vinylidene chloride and 20%.
Consists of weight percent vinyl chloride. The extrudate tape of the polymer composition showed good color.

Example 23 The procedure of Example 18 is repeated with the following exceptions. Instead of adding 27 g of orthophosphoric acid to the polymer slurry,
7 g of trisodium orthophosphate are added to the monomer mixture. The pH of the aqueous phase of the monomer mixture is adjusted to about 6.5. After the polymerization, the pH of the polymer slurry is adjusted to the value shown in Example 19. Next, the polymer slurry is cooled, removed, and dewatered. Extrudate tapes from the extruded polymer composition showed good color.

Example 24 The procedure of Example 23 is repeated with the following exceptions. The polymer composition is extruded a second time through a single strand die, passed through a water bath, and then pelletized. The strand die had an inner diameter of 0.32 cm. Pelletization was achieved using a Model 304, 15.24 cm strand cutter commercially available from Conair Incorporated. The extruded tape of the extruded pellets showed good color.

Examples 25-26 The procedure of Examples 23-24 is repeated with the following exceptions. The monomer mixture consists of 80% by weight of vinylidene chloride and 20%.
Consists of weight percent vinyl chloride. The extrudate tape of the polymer composition showed good color.

Examples 27-32 The procedure of Example 5 is repeated with the following exceptions. Instead of adding 45 g of tetrasodium pyrophosphate to the polymer slurry, 60 g of oxalic acid is added to the polymer slurry. Oxalic acid is commercially available from JTBaker Company.

After adding oxalic acid to the polymer slurry, the pH of the polymer slurry
Is adjusted to the values shown in Table III. The pH of the aqueous phase of the polymer slurry is adjusted with NaOH and maintained at various pHs as shown in Table III.

When oxalic acid dissolves in water, it hydrolyzes to form monohydrogen oxalate and oxalate anions. In the polymer composition, the reaction product of the oxalate anion is calculated as disodium oxalate in parts per 100 parts of vinylidene chloride interpolymer.

The results of Examples 27 to 32 are shown in Table III.Table III Example PS ¹ SO ² pH ³ colors ⁴ 27 100 0.4 4 1 28 100 0.4 5 1 29 100 0.4 6.1 1.4 30 100 0.4 6.8 1 31 100 0.4 9.3 1.4 32 100 0.4 11 1 PS ¹ = of the monomer mixture in 100 parts of polymer, polymerized from an initial monomer charge consisting of 94% by weight of vinylidene chloride monomer and 6% by weight of methyl acrylate Polymer slurry.

Oxalate disodium parts per 100 parts of the polymer of SO ² = polymer slurry.

pH ³ = pH of the aqueous phase of the polymer slurry after oxalic acid was added and adjusted to basic with NaOH.

Color ⁴ = by visual inspection.

As can be seen from the above table, the polymer composition can be extruded into extrudate tapes having excellent color, with the optimal color being obtained in a pH range of about 4 or higher.

Example 33 The procedure of Example 30 is repeated with the following exceptions. The polymer composition is extruded a second time through a single strand die, passed through a water bath, and then pelletized. The strand die had an inner diameter of 0.32 cm. Pelletization was achieved using a Model 304, 15.24 cm strand cutter commercially available from Conair Incorporated. The pellets are extruded into extruded tape in a continuous process for about 20 minutes. The extruded tape of the extruded pellets showed good color.

Examples 34-35 The procedure of Examples 30 and 33 is repeated with the following exceptions. The monomer mixture consists of 80% by weight of vinylidene chloride and 20%.
Consists of weight percent vinyl chloride. The extrudate tape of the polymer composition showed good color.

Example 36 The procedure of Example 30 is repeated with the following exceptions.
Instead of adding 60 g of oxalic acid to the polymer slurry, 8.5 g of sodium oxalate is added to the monomer mixture. The pH of the aqueous phase of the monomer mixture is adjusted to about 6.5.

After the polymerization, the pH of the polymer slurry is adjusted to the value indicated in Example 30. Next, the polymer slurry is cooled, removed, and dewatered. Extrudate tapes from the extruded polymer composition showed good color.

Example 37 The procedure of Example 38 is repeated with the following exceptions. The polymer composition is extruded through a second single strand die, passed through a water bath, and then pelletized. The strand die had an inner diameter of 0.32 cm. Pelletization was achieved using a Model 304, 15.24 cm strand cutter commercially available from Conair Incorporated. The extruded tape of the extruded pellets showed good color.

Examples 38-39 The procedure of Examples 36 and 37 is repeated with the following exceptions. The monomer mixture consists of 80% by weight of vinylidene chloride and 20%.
Consists of weight percent vinyl chloride. The extrudate tape of the polymer composition showed good color.

Example 40 The procedure of Example 5 is repeated with the following exceptions. Instead of adding 45 g of tetrasodium pyrophosphate to the polymer slurry, about 20 g of maleic acid is added to the polymer slurry. Maleic acid is commercially available from Fisher Scientific Com-pany.

The results are shown in Table IV. Table IV Examples PS ¹ TSPP ² MA ³ pH ⁴ colors ⁵ 40 100 0.5 0.1 91 PS ¹ = initial monomer charge consisting of 94% by weight of vinylidene chloride monomer and 6% by weight of methyl acrylate A polymer slurry of a monomer mixture in 100 parts of a polymer, which is polymerized from

TSPP ² = polymer 100 in polymer slurry when added
Parts per part tetrasodium pyrophosphate.

MA ³ = parts of maleic acid per 100 parts of polymer in polymer slurry when added.

pH ³ = pH of the aqueous phase of the polymer slurry after tetrasodium pyrophosphate and maleic acid have been added and adjusted.

Color ⁴ = by visual inspection.

As can be seen from the above table, the polymer composition can be extruded into extrudate tapes having excellent color.

Example 41 The procedure of Example 40 is repeated with the following exceptions. The polymer composition is extruded a second time through a single strand die, passed through a water bath, and then pelletized. The strand die had an inner diameter of 0.32 cm. Pelletization was achieved using a Model 304, 15.24 cm strand cutter commercially available from Conair Incorporated. The pellets are extruded into extruded tape in a continuous process for about 20 minutes. The extruded tape of the extruded pellets showed good color.

Examples 42-43 The procedure of Examples 40 and 41 is repeated with the following exceptions. The monomer mixture consists of 80% by weight of vinylidene chloride and 20%.
Consists of weight percent vinyl chloride. The extrudate tape of the polymer composition showed good color.

Although the invention has been described in considerable detail with respect to certain preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and scope of the invention as defined above and defined in the claims. .

Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08K 5/09 C08K 5/09 5/50 5/50 C08L 27/08 C08L 27/08 (56) References , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08F 214/08-214/10 C08F 2/44 C08F 220/06 C08F 222/02 C08L 27/08

Claims (4)

(57) [Claims] 1. A process for preparing a polymer composition, comprising: (A) a vinylidene chloride monomer in an amount of 60 to 99% by weight and 40% by weight.
Form a polymerizable monomer mixture having a monomer phase consisting of at least one ethylenically unsaturated comonomer copolymerizable therewith and an aqueous phase in an amount of １1% by weight, said weight% being (B based on the weight of the monomer mixture), (B) polymerizing the polymerizable mixture to form a polymer slurry having an aqueous phase and a polymer phase, and (C) drying the slurry to obtain a polymer composition. After the start of step (A) and before the completion of step (C), boric acid, hexapolyphosphoric acid, hypophosphorous acid, orthophosphoric acid, pyrophosphoric acid, phosphorous acid, tetrapolyphosphoric acid , Tripolyphosphoric acid, alkyl monocarboxylic acid, aryl monocarboxylic acid, alkyl polycarboxylic acid, aryl polycarboxylic acid, hydroxyalkyl monocarboxylic acid and hydroxyalkyl polycarboxylic acid. At least one salt of a non-alkene weak acid selected from the group consisting of 0.001 to 1 in either a polymerizable mixture or a polymer slurry without adding vitamin E and an alkyl thiopropionate.
0% by weight, maintaining the pH of the aqueous phase of the weight% slurry at 3-12. 2. The method of claim 1, wherein the at least one monomer copolymerizable with the vinylidene chloride monomer comprises vinyl chloride, alkyl acrylate, alkyl methacrylate, acrylic acid, methacrylic acid, itaconic acid, acrylonitrile and methacrylonitrile. The method of claim 1, wherein the method is selected from the group consisting of: 3. The non-alkene weak acid salt is added to the monomer mixture or polymer in an amount such that the resulting polymer composition contains the reaction product of the non-alkene weak acid salt in an amount of 0.05 to 3% by weight. 2. The method of claim 1 wherein the weight percent is added to any of the coalesced slurries, based on the total weight of the polymer composition. 4. The salt of a non-alkene weak acid is added to the monomer mixture or polymer in an amount such that the resulting polymer composition contains the reaction product of the salt of a non-alkene weak acid in an amount of 0.1 to 1% by weight. 2. The method of claim 1 wherein the weight percent is added to any of the coalesced slurries, based on the total weight of the polymer composition.