JPH07103285B2 - Improved processing aid composition - Google Patents

Description

The present invention relates to processing aids for vinyl chloride polymers, and more particularly dispersion aid polymers for improving the dispersion of conventional processing aids in vinyl chloride polymers. An improved processing aid composition for vinyl chloride polymers containing

[Conventional technology]

Polymeric processing aids are widely used in the manufacture of polyvinyl chloride (PVC) articles to improve the processing performance of PVC during extrusion, injection and / or thermoforming operations. Processing aids reduce the temperature required to melt PVC, improve the homogeneity and thermal strength of PVC, reduce melt fracture,
It reduces plate-out during processing and gives the final product excellent ductility. Lowering the melting temperature provides PVC with sustained thermal stability, providing a safety margin when using regrind and reducing processing time. Higher hot strength and reduced melt fracture allow the processor to extrude or calender PVC at a faster rate and with better surface quality. Reduced or removed plateout does not result in rejects due to plateout spots, and time consuming shutdowns to remove deposits that inhibit melt flow and lead to PVC degradation. The processing operation can be extended without. The homogenizing effect of the processing aid is extremely important when producing a product with markedly improved ductility and thermoformability. PVC obtained by including processing aids
The uniformity of the temperature dependent properties of the improves the overall ability of the processor to operate the device.

Also, processing aids generally improve the PVC's tensile strength, modulus, and to a small extent, heating strain temperature,
The impact strength does not improve, and in fact, adding a large amount reduces the impact strength of PVC.

Various types of polymeric processing aids have been developed for use in PVC. These processing aid polymers include
For example, high molecular weight polymethylmethacrylate having a weight average molecular weight of about 750,000 to 7 million, copolymers consisting mainly of methylmethacrylate and containing a small amount of alkyl acrylate, and acrylic and styrene, styrene and acrylonitrile, and poly (alphamethyl-styrene). There are acrylic polymers and copolymers, such as These processing aid polymers may be homopolymers, single-stage or multistage copolymers, or graft copolymers.

Not all conventional processing aids have similar average properties and efficiencies under different operating conditions. The composition, structure and / or staging, molecular weight and concentration etc. of processing aids in PVC are all relevant to their performance characteristics.

Poly (alphamethyl-styrene) processing aids are a notable exception, although processing aids are generally thermodynamically miscible and compatible with PVC, but when mixed in small amounts with PVC,
This modified PVC has a single glass transition temperature (Tg). Processing aids are generally compatible with PVC, but PVC
It has a much higher Tg than that of. For example, PVC is relatively soft and has a Tg of about 70 ° C, while polymethylmethacrylate type processing aids are about 95 ° C to about 105 ° C.
Has a degree of Tg. In addition, there is a difference in viscosity between the processing aid and PVC, which makes it difficult to obtain a homogeneous blend of the processing aid in PVC. Obtaining well-dispersed processing aids through PVC matrix is desirable for aesthetic and physical reasons. For example, if the processing aid is PV
If not well dispersed in C, the processing aid particles will harden and form a gel in PVC. These gels produce PVC products with an irregular or bumpy, undesired appearance. Furthermore, these gels or solids act as stress concentration points in PVC, promoting the generation and propagation of fractures and reducing the impact resistance of PVC.

Attempts have been made to improve the dispersion of processing aids in PVC by varying the processing conditions to break these gels or to change the structure of the processing aid polymer itself. Attempts to increase shear conditions during processing have been made to improve the dispersion of processing aids in PVC. However, increasing shear conditions reduces the achievable production of PVC products. Furthermore, attempts have been made to break the gel by increasing the energy acting on the modified PVC by lowering the operating temperature of the machine to raise the internal friction temperature or the shearing condition, but it has been found to be not perfect. Besides, for example, the first stage is 60
By making a multi-stage processing aid (US Pat. No. 3,833,686) having a Tg of less than or equal to ° C and the amount of the first stage is less than or equal to 25% by weight of the total processing aid. Attempts have also been made to alter the composition and / or structure of the processing aid itself.

Despite the widely recognized problem of dispersing processing aids in PVC, a universal solution to disperse processing aids is-without that method either settle for poor dispersion or It leads to a high concentration of gels in PVC-but not yet.

[Problems to be solved by the invention]

Therefore, it is an object of the present invention to provide an improved processing aid composition that disperses well in PVC to reduce the tendency of the processing aid to gel in modified PVC.

U.S. Pat. No. 4,440,905, Dunkel Spurs (Dunke
l spersers) appear to be the most relevant to the present invention.
This patent refers to the dispersant "Dunkelsper
sers) "polymer is used to disperse an elastomeric impact modifier in a rigid thermoplastic matrix polymer such as PVC. The elastomeric impact modifier is structurally different from the processing aid, and Acts completely different from processing aids in PVC Elastomeric impact modifiers are usually methacrylate-butadiene-styrene (MBS),
Acrylonitrile-butadiene-styrene (ABS) and others such as U.S. Patents 2,802,809, 2,943,074, 3,251,90
Core-shell or multi-stage rubbery polymers such as those described in 4,3,678,133, 3,793,402 and 3,899,547;
Or a linear or cross-linked one-step rubbery polymer such as polybutadiene, butadiene / styrene acrylonitrile, linear ethylene-propylene copolymers; segmented block copolymers such as butanediol-polytetramethylene ether diol terephthalate ester; or It is a polymer modified to give elastomeric behavior like chlorinated polyethylene. Another example of an elastomeric impact modifier is US Pat.
0,905.

Impact modifiers are synthesized into elastomer-based thermoplastic tougheners. These are insoluble in thermoplastics and their function can be compared to the action of rubber balls suspended in a polymer matrix. When an impact modifier is added to PVC, a two-phase system with various glass transition temperatures is formed. In order for the modified thermoplastic polymer to have uniform toughness and impact efficiency, these impact modifiers or rubbery spheres must be evenly distributed throughout the polymer matrix. “Dunkelspersers” because the criteria required to synthesize impact modifier compositions are different compared to processing aids and because the mechanism by which impact modifiers act in thermoplastics is different. It was quite unexpected for the person skilled in the art of PVC additives that the polymers could be useful as dispersion aid polymers in combination with conventional processing aids for PVC.

[Means for solving problems]

Broadly speaking, the improved processing aid compositions of the present invention are conventional
PVC processing aid polymer (a) and dispersion aid polymer (b)
More specifically, the processing aid polymer (a) of the present invention is made from methyl methacrylate and 0 to 50% by weight of (C ₁ -C ₄ alkyl) -acrylate, and the dispersion aid polymer (b) ) Is at least 50% by weight of one or more of the following monomers: (C ₁ -C ₈ alkyl) -acrylate, (C ₆ -C ₉ cycloalkyl) -acrylate,
It is a homopolymer or copolymer made of ethylene, propylene, vinyl acetate and butadiene, and the weight ratio of processing aid polymer (a) to dispersion aid polymer (b) is from 99.5 to 0.5 to 90 to 10, preferably 99. It is directed to improved processing aid compositions which are from 1 to 95: 5.

More specifically, the present invention relates to 1.5-100% by weight of ethyl acrylate or butyl acrylate, 0-98.5% by weight of unsaturated monomer having a copolymerizable single-ethylene bond, and copolymerizable multifunctional crosslink formation. Polymer (A), which is a first-stage polymer from a monomer mixture of 0-10% by weight of monomers, is relatively soft and has a glass transition temperature of 25 ° C. or lower, and 1.5-100% by weight of methyl methacrylate. And styrene, ethyl acrylate, butyl acrylate,
A relatively hard and substantially thermoplastic resin obtained by sequential polymerization of a monomer mixture consisting of 98.5-0% by weight of butyl methacrylate or a mixture of these and a copolymerizable monomer in the presence of the first-stage polymer. Polymer (B) which is a polymer and is in intimate contact with the polymer (A) (however, the polymer (B) is 25 ° C or higher when obtained in the absence of the polymer (A). A glass transition temperature of 1 to 25% by weight of the polymer (A), and the polymer (A) is 1 to 25% by weight, and the polymer (B) is 99-.
(A) containing 75% by weight, polybutyl acrylate, polyethyl acrylate, polybutadiene, ethyl acrylate and styrene, butyl acrylate and styrene,
A dispersion aid polymer (b) selected from the group consisting of butadiene and styrene, butyl acrylate and methyl methacrylate, ethyl acrylate and butyl methacrylate, and butyl acrylate and styrene and methyl methacrylate copolymers, and (a) and (b). To a modified processing aid polymer composition for vinyl chloride polymers, wherein the weight ratio of a) ranges from 99.5: 0.5 to 90:10.

The present invention also provides a PVC containing improved processing aid composition.
The present invention is directed to compositions, and to improved processing aid compositions and methods of making the modified PVC compositions.

The processing aid polymer (a) dispersed in PVC by the dispersion aid polymer (b) is a conventional multistage polymer disclosed in US Pat. No. 3,833,686. That is, the processing aid polymer (a) is composed of 1.5-100% by weight of ethyl acrylate or butyl acrylate, 0-98.5% by weight of an unsaturated monomer having a copolymerizable single ethylene bond, and a polyfunctional crosslinkable copolymer. 1 to 25% by weight of the polymer (A), which is a relatively soft polymer having a glass transition temperature of 25 ° C. or less, which is a first-stage polymer from a monomer mixture containing 0 to 10% by weight of a bond-forming monomer. A mixture of 1.5-100% by weight of methyl methacrylate and styrene, ethyl acrylate, butyl acrylate, butyl methacrylate or a monomer copolymerizable therewith in the presence of the first-stage polymer.
A relatively hard and substantially thermoplastic final stage polymer obtained from a monomer mixture consisting of 98.5-0% by weight, the polymer (B) being in intimate contact with said polymer (A).
(However, this polymer should exhibit a glass transition temperature of 25 ° C. or higher when obtained in the absence of the above polymer (A).). Dispersion aid polymer (b) is at least 50% by weight of one or more of the following polymers: (C ₁ -C ₈ alkyl) -acrylate, (C ₆ -C ₉
Cycloalkyl) -acrylates, ethylene, propylene, vinyl acetate and butadiene, homopolymers or copolymers made from. Preferably the dispersion aid polymer (b) is one of the following polymers: poly (butyl acrylate), poly (ethyl acrylate), polybutadiene, poly (ethyl acrylate / styrene), poly (butyl acrylate / styrene). , Poly (butyl acrylate / methyl methacrylate), poly (ethyl acrylate / butyl methacrylate), poly (butadiene / styrene) and poly (butyl acrylate / styrene / methyl methacrylate). These polymers are made from up to 50% by weight of methacrylate and / or styrene monomers. Other suitable dispersing polymers (b) include poly (vinyl acetate) and poly (ethylene / vinyl acetate).

The molecular weight range of suitable dispersion aid polymer (b) is broad and ranges from about 15,000 to about 100,000 by weight average molecular weight.
The dispersing aid polymer (b) may preferably be crosslinked and / or grafted to the extent of up to 5% by weight of crosslinking or grafting units. This cross-linking and / or grafting makes it difficult to determine the molecular weight of the final dispersion aid polymer (b).

The dispersion aid polymer (b) is generally a single stage polymer but may be a multistage polymer. When the dispersion aid polymer (b) is a multi-stage polymer, the total monomer composition used to make this polymer and the composition of the outermost stage are:
Even if the inner steps do not match, the composition parameters defined above must be met, ie those steps are made up of 50% by weight or less of methacrylate and / or styrene monomer. Dispersion aid polymer (b) should not be confused with any polymer incidentally generated during the preparation of multi-stage processing aid polymer (a). The reason is that such an accessory polymer does not function as the dispersion aid polymer (b) of the present invention.

Dispersion aid polymer (b) is intimately mixed with processing aid polymer (a) to form the improved processing aid composition of the present invention. Any method of making a completely intimate mixture of dispersion aid polymer (b) and processing aid polymer (a) is suitable. However, a simple mixture of polymeric processing aid powder and dispersion aid polymer is generally insufficient unless intimate thorough mixing is achieved. One method of making the improved processing aid composition of the present invention is by emulsion polymerizing the dispersion aid monomer in the presence of the latex of the processing aid polymer (a) made by emulsion polymerization. To produce the dispersion aid polymer (b). The presently preferred method is to separately prepare the emulsion of the processing aid polymer (a) and the emulsion of the dispersion aid (b), mix these emulsions and then spray dry or coagulate these two. Co-separating the polymers. Spray Drying, Introduction of Principles, Operational Practicality and Applications, by K. Masters, Cleveland, Ohio CRC Newspaper Edition (1972) (Spray Drying, An Introductio
n to Principles, Operational Practices, and Applicat
Spray drying is described in detail in ions, K. Masters, CRC Press, Cleveland Ohio (1972). Coagulation or polymer emulsions are provided, for example, in twice their volume of the following salts and / or acids such as NaCl, KCl, CaCl ₂ , Na ₂ SO ₄ , MgSO ₄ , acetic acid, oxalic acid, HCl, HNO ₃ , H ₂ SO ₄ and It is applicable to salt out the stabilizing surfactant from the emulsion by gradually adding it to the electrolyte solution containing one of the H ₃ PO ₄ .
The polymer is then over-separated, washed several times with fresh water to remove excess electrolyte and dried.

Processing aid polymer (a) and dispersion aid polymer (b)
Can also be separated from the emulsion mixture by evaporation or freeze-drying.

When following these preferred preparative separation methods, it is important that the two emulsions are compatible and do not precipitate before the co-separation step, preferably before the coagulation step. For example, the surfactants used to prepare the two emulsions must be of the same or similar type, i.e., of the same ionic species, and of similar water-soluble or hydrophilic-lipophilic balance. I have to.

The weight ratio of processing aid polymer (a) to dispersion aid polymer (b) is in the range of 99.5: 0.5 to 90:10, preferably 99: 1 to 95: 5. Most preferably the weight ratio of processing aid polymer (a) to dispersion aid polymer (b) is about 98: 2.
To about 96 to 4.

The vinyl chloride polymer to be modified with the improved processing aid composition (a plus b) of the present invention includes polyvinyl chloride and at least 50% by weight vinyl chloride monomer and up to 50% by weight or 50% by weight. Copolymers made from at least one other monomer, such as vinyl acetate and / or ethyl vinyl acetate.

The weight ratio of the vinyl chloride polymer to the modified processing aid composition may be the same as the weight ratio currently used for vinyl chloride polymers and conventional processing aids. Usually, this weight ratio is in the range of 90:10 to 99.5: 0.5 by weight of the vinyl chloride polymer to the modified processing aid composition, and more typically in the range of 95: 5 to 99: 1 by weight.

Other standard additives may be used to make the vinyl chloride polymer formulation. For example, impact modifier, colorant,
Pigments, plasticizers, stabilizers and lubricants can also be added to the formulation.

After the PVC formulation is prepared, the formulation can be processed by standard methods such as blow molding, calendering, injection molding and extrusion to produce an essentially gel-free article. .

Examples Some preferred embodiments of the present invention are illustrated in the following examples. These examples are intended to illustrate the invention and should not be construed as limiting the scope of the invention. Comparative tests were also carried out with conventional processing aids and with compounds initially thought to be suitable as dispersion aid polymer (b). It is clearly seen from these examples that some of these polymers failed the dispersibility evaluation test and are therefore not within the scope of the invention.

For this dispersibility evaluation test, PV containing conventional additives was used.
C master batch preparation was included. Two parts of conventional processing aid (a) was added to the PVC master batch to make a roll mill rolled control sample. A rating of 100 was assigned to a control sample that failed completely because it contained many undispersed particles (gels). But later on during the experiment
It is also possible to make small pieces from a PVC master batch with the addition of 2 parts of processing aid (a) and a roll machine that has less dispersibility (more gel) than the initial small pieces used as a control in Examples 1-16. Wakatsuta. Examples 17-19 compare the effect of two improved processing aid compositions of the present invention to disperse a second PVC control compounded processing aid polymer (a) having a dispersibility rating of 100 or greater. .

The dispersant aid polymer (b) and the general method used to prepare the PVC master batch are then described. All parts and percentages (%) are by weight unless otherwise specified.

Dispersion aid polymer Dispersion aid polymer (b) was prepared in aqueous emulsion using the ingredients and methods described below.

Method Deionized water (A) was placed in a one-necked four-necked flask equipped with stirrer, thermometer, nitrogen inlet and condenser. This water
It heated at 65 degreeC and stirred for 10 minutes. The KPS initiator (E) was then added and further 15% of the monomer (C) and chain transfer agent and / or BDA difunctional monomer (D) were added and the temperature was kept at 65 ° C until an exotherm was observed.

At this point a second emulsifier (B1) was added, and then the rest of the monomer (C) and chain transfer agent and / or BDA difunctional monomer (D) was added slowly over an hour.
After the addition of the monomer and chain transfer agent and / or difunctional monomer is complete, the batch is kept at 65 ° C for 15 minutes,
Then it was cooled to room temperature.

PVC Master Batch A PVC master batch formulation without the processing aid composition of the present invention was prepared from the following ingredients.

Department PVC (K-58) resin 100 Sulfur-containing organotin stabilizer 2.0 Plasticizer-dioctyl phthalate (DOP) 5.0 Lubricant system: Stearic acid 1.0 and Rohm and Haas Acryloid K-1753.0 (Rohm and Haas Company Acryloid K-175) PVC plus processing aid 2 parts conventional processing aid and improved processing aid composition of the present invention.
2 parts separately as a powder into a PVC master batch formulation
In addition, Prodex-Hensche
l) Mix evenly in the blender to make the final PVC plus
I made a sample of industrial aid.

Each final formulation was rolled on a two roll Schwabenthan roll machine with two chrome polishing rolls. Roll size 35 cm length (actuator length 30 cm) diameter 15
cm. The temperature of this two-roll machine is 190 ℃, and the speed is 26/20 rpm.
(Front / rear roll). The film is formed by the front roll, and after the standard work to obtain a uniform film is completed, the roll machine is stopped, a horizontal piece of about 4 to 5 cm width is cut to the full length of the roll, and it is taken out from the roll. The length was immediately doubled using a guide of different length. Each piece was held in the extended position until it cooled.

Each piece rolled and rolled, 0 equals a small piece with no non-dispersed particles (no gel) and 100 with many non-dispersed processing aid particles (gels) as standard control (PVC plus conventional processing aid). Of the non-dispersed processing aid particles (gel) using an evaluation system from 0 to 100 (excluding Examples 17-19 as described above), which correspond to small pieces of agent (a) only. It was evaluated according to the amount. In each of a series of PVC dispersion evaluations, at least one sample of conventional processing aid (a) without dispersion aid (b) was run as a control. Materials rated 100 or higher (Example 17-1)
The 9 controls) contain an unacceptable number of gels. 40
A dispersibility rating of 50 to 50 is considered to be a very good rating based on 100 as a control, while 70 based on 100 is considered
All of the above have commercially unacceptable numbers of undispersed gels. Example 17 where the control was rated worse than 100
At -19, a rating of 90 or less indicates a significant improvement in processing aid dispersion.

Less than the control (rated 100) to determine if a given processing aid composition is effective in substantially reducing the gel mass of processing aid (a) in a polyvinyl chloride formulation. Both are required to be reduced by 30 units. A preferred dispersing aid (b) is at least 45 than the control formulation rated at 100.
It showed a decrease in units.

In the examples below, the following abbreviations are used:

Methyl Methacrylate = MMA Butyl Methacrylate = BMA Styrene = St Methyl Acrylate = MA Ethyl Acrylate = EA Butyl Acrylate = BA Butadiene = Bd Examples 1-8 In these examples shown in Table 1, the procedure described above is followed. Various dispersion aid polymers (b) are used as monomers (C)
Was prepared in an aqueous emulsion using 4% t-DDM (D) as a base. This dispersion aid emulsion was mixed with a conventional methyl methacrylate-ethyl acrylate processing aid (a) emulsion so that the weight ratio of polymer (b) to polymer (a) was 3:97. The mixed emulsion was then separated by spray drying. The ratio of improved processing aid composition (a plus b) to PVC in the master batch was 2 parts to 100 parts PVC.

90/1 of methyl methacrylate, styrene and methyl methacrylate and ethyl acrylate from these examples
The 0 copolymer is a dispersion aid polymer (b) that is unacceptable for use in the processing aid composition of the present invention, while polyethyl acrylate, butyl acrylate and 50%
The following butyl acrylate-styrene copolymer consisting of styrene is found to be an effective dispersion aid polymer (b) for processing aids in PVC.

Examples 9-13 In these examples, the relationship between the composition of the dispersion aid polymer (b) and its molecular weight was investigated. A series of low and high molecular weight dispersion aid polymers (b) were added at 4% and 0% t-, respectively.
It was prepared using a chain transfer agent of dodecyl mercaptan.
The low molecular weight dispersion aid polymer (b) had a molecular weight in the range of 19,000 to 38,000, and the high molecular weight dispersion aid polymer (b) had a molecular weight in the range of 137,000 to 3,890,000. In each example, the ratio of dispersion aid polymer (b) to processing aid polymer (a) was 3:97 by weight, and the processing aid composition (a plus b) was present in 2 parts by weight per 100 parts of PVC. .
Dispersibility evaluation was performed according to the general method used in Examples 1-8. The results are shown in Table 2.

The low and high molecular weight polybutyl acrylate and polyethyl acrylate dispersion aid polymers (b) (Examples 10 and 11) are effective in dispersing the processing aid polymer (a) in PVC. Although the effect of these dispersion aids is slightly reduced as the molecular weight decreases, it does not decrease remarkably as the dispersion aid polymer (b) becomes ineffective. Polymethylmethacrylate and polystyrene, both high molecular weight and low molecular weight, are not effective dispersion aid polymers (b) for processing aids.

Examples 14-19 To investigate the effect of the ratio of dispersion aid polymer (b) to processing aid polymer (a) in emulsion mixture on the dispersion of processing aid (a) in PVC, Example 2 Experiments were carried out with dispersion aid polymers (b) of 4 and 4.

In Examples 14-16, the ratio of (a) and (b) was 98.5 to 1.5, respectively.
And butyl acrylate / styrene (55:45) dispersion aid polymer (b) in the processing aid composition at 97 and 3/3. Polymethylmethacrylate, which is not a suitable dispersion aid (b) as shown in Example 6, was also evaluated at this same concentration. In Examples 17-19,
The ethyl acrylate dispersion aid polymer and the butyl acrylate-styrene (55:45) dispersion aid copolymer (b) were investigated when the ratios of (a) to (b) were 97.5 to 2.5 and 95: 5. However, the PVC processing aid control used in this test (Example 17) was far inferior to the previously prepared control which exhibited a dispersibility rating of 100.
The results are shown in Table 3.

In Example 15, BA / St (55:45) dispersion aid copolymer (b)
Has been found to be acceptable as a dispersion aid polymer for processing aid (a) at addition levels of 1.5% and even higher addition levels of 3%. 1.5 for MMA sample (Example 16)
% Or 3% addition level is not acceptable as dispersion aid polymer (b).

In Examples 17-19, the EA and BA / St dispersion aid polymers (b) exhibit a dispersibility rating of 100 or greater and are very poorly dispersed P
It has been found to result in acceptably improved dispersion compared to the VC control sample. The control sample of Example 17 was far inferior to any of the previous control samples in terms of gel formation, and a rating of 90 or less could indicate a significant improvement over the control sample. The conclusion drawn from Examples 14-19 is that the dispersion of the processing aid improved when the concentration of the dispersion aid polymer (b) was increased in the range of 1.5 to 5% relative to the processing aid polymer (a). Is.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hobart Thomann Germany 6230 Frankfurt 80 Buchenciutlerse 10 (72) Inventor Gierall Goose France 67630 Router Bourg Lieu de la Chapeur 26 (72) Inventor William Ale Carter UK Katy 11 2 RSP Cobalm Broad Highway 18 Hillside (56) Reference JP-A-57-5755 (JP, A)

Claims (3)

[Claims] 1. An ethyl acrylate or butyl acrylate, 1.5-100% by weight, 0-98.5% by weight of a copolymerizable unsaturated monomer having a single-ethylene bond, and 0-10 of a copolymerizable polyfunctional crosslinking bond-forming monomer. Polymer (A) which is a first-stage polymer from a monomer mixture of wt% and is relatively soft and has a glass transition temperature of 25 ° C or lower.
And 1.5-100% by weight of methyl methacrylate and styrene,
A relatively hard mixture obtained by sequentially polymerizing a monomer mixture comprising ethyl acrylate, butyl acrylate, butyl methacrylate or a mixture of these and a copolymerizable monomer with 98.5-0% by weight in the presence of the first-stage polymer. Polymer (B) which is a substantially thermoplastic polymer and is in intimate contact with the polymer (A) (wherein the polymer (B) is obtained in the absence of the polymer (A)). 25 when
It should exhibit a glass transition temperature of ℃ or higher. A) containing 1 to 25% by weight of the polymer (A) and 99 to 75% by weight of the polymer (B) with respect to the total weight of the processing aid, Selected from the group consisting of acrylates, polyethyl acrylate, polybutadiene and ethyl acrylate and styrene, butyl acrylate and styrene, butadiene and styrene, butyl acrylate and methyl methacrylate, ethyl acrylate and butyl methacrylate, and butyl acrylate and styrene and methyl methacrylate. Dispersion aid polymer (b), and the weight ratio of (a) and (b) is 99.5:
An improved processing aid polymer composition for vinyl chloride polymers in the range of 0.5 to 90:10. 2. An improved processing aid polymer composition according to claim 1, wherein the copolymer as dispersion aid polymer (b) has a methacrylate or styrene content of less than 50% by weight. 3. The dispersion aid polymer (b) is selected from the group consisting of polyethyl acrylate, polybutyl acrylate and copolymers of butyl acrylate with less than 50% by weight of styrene. An improved processing aid polymer composition as described in claim.