High molecular weight acrylic processing aid concentrates for thermoplastic processing

Abstract

A pelletized composition is disclosed, the pelletized composition comprising a high molecular weight processing aid and optionally one or more additional components. The high molecular weight processing aid is present in an amount in the range of 50 wt% to 100 wt% relative to the total weight of the composition, and the one or more additional components is present in an amount in the range of 0 wt% to 50 wt% relative to the total weight of the composition. The pelletized composition does not contain a carrier resin. The pelletized composition is in the form of particles having a D50 particle size ranging from 1 mm to 30 mm and a D10 particle size of at least 50% of the D50 particle size.

Description

TECHNICAL FIELD

[0001] The field of the invention is high molecular weight acrylic processing aid concentrates. BACKGROUND

[0002] Polyvinyl chloride (PVC) is widely used in a variety of applications, including building and construction products such as fencing, siding, decking, trim, paneling, window frames, door thresholds, and doors. PVC polymer virgin resins are typically supplied in powder form. PVC is typically formulated by dry blending with other components also in powder form, and hot processed into final products by melt extrusion.

[0003] Acrylic processing aids are typically one of the powdered components incorporated into PVC formulations. Acrylic processing aids are typically added to PVC in parts per hundred resin (phr).

[0004] Environmental sustainability is driving interest in reusing and recycling materials, including PVC, to increase the amount of post-consumer or post-industrial waste in the material stream. When incorporated into PVC formulations, post-consumer or post-industrial waste PVC is typically mixed with virgin PVC powder. However, using waste PVC creates problems.

[0005] Recycled PVC is pulverized from parts that have already been formed. The pulverized PVC particles are typically much larger than virgin PVC powder. The difference in particle size presents problems when mixed prior to extrusion. These problems can include particle segregation and uneven mixing of the composition.

[0006] Similarly, when pulverized PVC particles, typically having a particle size of greater than 35 mesh (500 microns), more typically greater than 18 mesh (1 mm), are mixed with commercially available powdered processing aids having an average particle size of about 50 microns to 500 microns, problems arise due to the size difference between the pulverized PVC and the processing aid. Similar to mixing pulverized PVC with virgin PVC powder, mixing pulverized PVC with powdered processing aids results in particle segregation, which in turn causes uneven mixing prior to extrusion.

[0007] Another problem arises when using waste PVC due to the fact that many PVC formulations already contain added components from the original formulation. Because these added components are not removed during the pulverization process, the waste PVC particles will have a different composition than virgin PVC powder.

[0008] WO 2022 / 072220 A1 discloses a composition comprising a high molecular weight processing aid, wherein the composition has an average particle size of at least 2 mm. However, the composition disclosed in WO 2022 / 072220 A1 requires the presence of a carrier resin as an inert component or an active component of the composition.

[0009] The presence of carriers can result in problems with using scrap PVC due to changes in composition. When scrap PVC is used, greater control over the composition is desired when adding processing aids or other components.

[0010] The present invention seeks to address one or more of the above problems. SUMMARY

[0011] Disclosed herein is a pelletized composition comprising a high molecular weight processing aid and one or more additional components selected from the group consisting of lubricants, heat stabilizers, antioxidants, fillers, and colorants. The high molecular weight processing aid is present in an amount ranging from 50 wt% to 100 wt% relative to the total weight of the composition and the one or more additional components are present in an amount ranging from 0 wt% to 50 wt% relative to the total weight of the composition. The pelletized composition does not comprise a carrier resin. The pelletized composition is in the form of particles having a D50 particle size ranging from 1 mm to 30 mm and a d10 particle size of at least 50% of the D50 particle size.

[0012] Also disclosed herein is a polyvinyl chloride composition comprising a polyvinyl chloride resin and a pelletized composition comprising a high molecular weight processing aid and one or more additional components selected from the group consisting of lubricants, heat stabilizers, antioxidants, fillers, and colorants, wherein the high molecular weight processing aid is present in an amount ranging from 50 wt% to 100 wt% relative to the total weight of the composition and the one or more additional components are present in an amount ranging from 0 wt% to 50 wt% relative to the total weight of the composition. The pelletized composition does not comprise a carrier resin. The pelletized composition is in the form of particles having a D50 particle size ranging from 1 mm to 30 mm and a d10 particle size of at least 50% of the D50 particle size.

[0013] Also disclosed is a method of making a polyvinyl chloride composition and articles made therefrom. DETAILED DESCRIPTION

[0014] Disclosed herein is an improved processing aid for use in polyvinyl chloride compositions. The processing aid of the present invention is a pelletized composition comprising a high molecular weight processing aid and one or more additional components, wherein the pelletized composition is in the form of particles having a D50 particle size ranging from 1 mm to 30 mm and a d10 particle size of at least 50% of the D50 particle size. The pelletized composition does not comprise a carrier resin.

[0015] As used herein, a "granulated composition" is a composition comprising particles in the form of aggregated, clustered, grouped, coalesced, consolidated, or agglomerated smaller particles. For example, a granulated composition can be formed by first drying a composition to form a powder, and then further processing the powder to form a larger collection of powdered particles.

[0016] As used herein, a "high molecular weight processing aid" is a processing aid having a weight average molecular weight of at least 500,000 g / mol. Preferably, the high molecular weight processing aid has a weight average molecular weight of at least 5,000,000 g / mol. More preferably, the high molecular weight processing aid has a weight average molecular weight of at least 10,000,000 g / mol.

[0017] As used herein, "average particle size" is the arithmetic average of all possible diameters. The aspect ratio of a particle is the ratio of the longest diameter to the shortest diameter. The particles can have any shape, including, for example, spherical, cylindrical, oval, cubic, prismatic, or irregular. As used herein, the terms "D10" and "D50" particle size values refer to the size at which 10% and 50% by mass, respectively, of the granulated composition has a diameter less than or equal to the stated value. Thus, a D10 value refers to the particle size at which 10% by weight of all particles of the granulated composition are smaller than the specified particle size. A D50 value is the "weight median particle size" at which 50% by weight of all particles of the granulated composition are smaller than the specified particle size.

[0018] High molecular weight polymer processing aids useful in the present application include polymers and copolymers containing vinyl aromatic, (meth)acrylonitrile, and (meth)alkyl acrylate monomers. As used herein, "(meth)acrylonitrile" includes both methacrylonitrile and acrylonitrile monomers. Similarly, "(meth)alkyl acrylate" includes both methacrylic acid alkyl ester and acrylic acid alkyl ester monomers.

[0019] Preferably, the high molecular weight processing aid is a copolymer comprising (meth)alkyl acrylate monomers. For example, the high molecular weight processing aid is a copolymer comprising methyl (meth)acrylate. The methyl (meth)acrylate copolymer can comprise, for example, monomers selected from other (meth)alkyl acrylate monomers, such as ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Exemplary high molecular weight processing aids include copolymers containing a majority (i.e., at least 50% by weight relative to the total weight of the high molecular weight processing aid) of methyl methacrylate ("MMA") and a minority (i.e., less than 50% by weight relative to the total weight of the high molecular weight processing aid) of alkyl acrylate (e.g., ethyl acrylate, butyl acrylate, or 2-ethylhexyl acrylate).

[0020] High molecular weight processing aids can include core-shell processing aids that combine the external lubricant functionality with the processing aid functionality. These "lubricious processing aids" provide the typical processing performance characteristics of acrylic processing aids, but with the added benefit of external lubrication functionality that improves flow and machine run times by significantly reducing the adhesion of the molten polyvinyl chloride resin to the hot metal surfaces of the processing equipment.

[0021] Commercially available high molecular weight processing aids can be obtained under the trade designation PARALOID K 300® ™ and SURECEL 21607-XP®. ™ from The Dow Chemical Company, Midland, Michigan. One preferred high molecular weight processing aid is SURECEL 21607-XP®. ™ 21607-XP.

[0022] The high molecular weight processing aid is preferably present in an amount ranging from 50 wt% to 100 wt% relative to the total weight of the pelletized composition. For example, the high molecular weight processing aid can be present in an amount of at least 60 wt%, at least 65 wt%, at least 70 wt%, at least 75 wt%, at least 80 wt%, at least 85 wt%, at least 90 wt%, or at least 95 wt% relative to the total weight of the pelletized composition. The high molecular weight processing aid can be present in an amount of less than 95 wt%, less than 90 wt%, less than 85 wt%, less than 80 wt%, less than 70 wt%, or less than 60 wt% relative to the total weight of the pelletized composition. Preferably, the high molecular weight processing aid is present in an amount ranging from 60 wt% to 100 wt%, more preferably 70 wt% to 100 wt%, even more preferably 80 wt% to 100 wt%, and still more preferably 90 wt% to 100 wt% relative to the total weight of the pelletized composition. In one preferred embodiment, the high molecular weight processing aid comprises 100 wt% of the total weight of the pelletized composition, i.e., the pelletized composition consists of the high molecular weight processing aid.

[0023] The composition can also include one or more additional components, including lubricants, heat stabilizers, antioxidants, fillers, colorants, and other additives. When present, these additional components can be present in an amount ranging from greater than 0 wt% to 50 wt% relative to the total weight of the pelletized composition, such as, for example, in an amount ranging from greater than 0 wt% to 40 wt%, 1 wt% to 35 wt%, 2 wt% to 30 wt%, or 5 wt% to 25 wt% relative to the total weight of the pelletized composition.

[0024] Suitable lubricants that can be used in the composition include internal lubricants and external lubricants, as well as lubricants that have a balance between internal and external lubrication properties. Generally, external lubricants dictate the behavior of the thermoplastic compound at the interface with other materials, such as delaying fusion / gelation and reducing adhesion and friction, and internal lubricants affect the rheological processes within the polymer phase, for example, providing lubrication between polymer chains and improving melt flow. Examples of lubricants include, for example, esters (such as monoglycerides), hydrocarbon waxes (such as paraffin wax, polyethylene wax, and oxidized polyethylene wax), esters, stearyl alcohol, fatty acids (such as stearic acid), fatty acid amides (such as ethylene bis-stearamide (i.e., two C16-C18 alkyl groups covalently bonded to a central polar amide group)), soaps, and stearates (such as calcium stearate). Suitable external lubricants include, but are not limited to, long chain montanic acids (i.e., long chain C28-C32 alkyl groups covalently bonded to a polar group such as a carboxylic acid), paraffins and hydrocarbons with short branched alkyl groups, n-paraffins with long straight chain hydrocarbons, polyethylene waxes with very long straight chain hydrocarbon chains with several branches. Suitable lubricants that provide a balance between internal and external lubrication include synthetic fatty acids that are partially saponified with calcium and long chain montanic esters (e.g., Wax OP and Wax E available from American Hoechst Corp., Mountainside, N.J.). Further information on lubricants for PVC can be found in the review “Update: Lubricants for PVC” by McMurrer, M. C., Plastics Compounding, pp. 74.-90, July / August 1982.

[0025] Suitable antioxidants include, but are not limited to, phenolic antioxidants, phosphate ester antioxidants, sulfur antioxidants, and blends thereof. Exemplary antioxidants include those sold under the ADK STAB brand by Adeka.

[0026] Examples of suitable heat stabilizers for the composition include, but are not limited to, organotin stabilizers (e.g., MARK STAB® 6220 organic tin heat stabilizer from Galata Chemicals), mixed metal heat stabilizers (e.g., MARK STAB® 6221 mixed metal heat stabilizer from Galata Chemicals), and phosphite stabilizers (e.g., MARK STAB® 6222 phosphite heat stabilizer from Galata Chemicals). ® ® ®

[0027] ​​​The granulated composition of the present invention does not comprise a carrier resin. This includes both inert carrier resins as well as active carrier resins which can have some activity as processing aids. Thus, the granulated composition of the present invention does not comprise a carrier resin, such as immiscible polymers such as polyethylene, polyethylene terephthalate, polypropylene, and inorganic materials such as talc, calcium carbonate and fibres, or active carrier resins, such as terpolymers such as ethylene terpolymers and polyethylene waxes.

[0028] In WO 2022 / 072220 Al, compositions comprising a high molecular weight processing aid and a carrier resin are disclosed. The present inventors have surprisingly found that a granulated composition can be prepared in the absence of a carrier resin.

[0029] The granulated composition of the present invention can be prepared, for example, by blending the high molecular weight processing aid and the additional component(s), if present, as powders, and then processing the blended composition to form larger particles. The present inventors have found that special processing is required to form the larger particles to avoid reducing the molecular weight of the processing aid, which can occur during the application of shear forces during processing. For example, the particles of the granulated composition can be formed by compaction, compression or by low shear extrusion.

[0030] The composition of the present invention is present in the form of particles having a D50 particle size of at least 18 mesh or 1 mm. For example, the particles can have an average particle size of at least 10 mesh (2 mm), at least 8 mesh (2.38 mm), at least 6 mesh (3.36 mm) or at least 5 mesh (4 mm). When compared to fine

[0031] When used with a ground resin, the average particle size of the composition can be less than 10 mesh. Preferably, the D50 particle size of the particles of the granulated composition is in the range of 1 mm to 30 mm, more preferably 2 mm to 20 mm.

[0032] The D10 particle size of the particles of the granulated composition is at least 50% of the D50 particle size. For example, if the D50 particle size is 2 mm, the D10 particle size is at least 1 mm. Preferably, the D10 particle size is at least 60% of the D50 particle size, more preferably at least 70% of the D50 particle size, and even more preferably at least 80% of the D50 particle size. When the D10 particle size is closer to the D50 particle size, it is believed that there are fewer small particles present in the granulated composition, which will increase the likelihood of delamination or separation of a composition using the granulated composition.

[0033] The particulated composition can comprise, consist of, or consist essentially of, from 50 wt% to 100 wt% of the high molecular weight process aid and from 0 wt% to 50 wt% of the one or more additional components selected from the group consisting of lubricants, heat stabilizers, antioxidants, fillers, and colorants, wherein the weight percentages are based on the total weight of the composition. As used herein, the term "consisting essentially of means that the particulated composition comprises less than 5 wt% of any component other than the high molecular weight process aid and the one or more additional components selected from the group consisting of lubricants, heat stabilizers, antioxidants, fillers, and colorants. Preferably, the particulated composition comprises less than 2 wt% of any component other than the high molecular weight process aid and the one or more additional components selected from the group consisting of lubricants, heat stabilizers, antioxidants, fillers, and colorants.

[0034] The polyvinyl chloride (PVC) composition can be prepared by blending a polyvinyl chloride resin with particles of the particulated composition comprising a high molecular weight process aid. The particulated composition comprising a high molecular weight process aid can be present in the PVC composition, for example, in an amount ranging from 0.5 to 20 parts per hundred resin (phr). For example, the particulated composition comprising a high molecular weight process aid can be present in the PVC composition, for example, in an amount ranging from 1 phr to 15 phr or from 2 phr to 10 phr.

[0035] Preferably, the polyvinyl chloride resin comprises recycled PVC. As used herein, "recycled PVC" refers to post-consumer or post-industrial waste, i.e., non-pristine PVC. Typically, recycled PVC is processed by pulverizing articles made from polyvinyl chloride. The pulverization process produces polyvinyl chloride particles having an average particle size ranging from, for example, 1 mm to 30 mm. Preferably, the average particle size of the recycled PVC is 0.5 times to 15 times the average particle size of the granulated composition, more preferably 1 times to 10 times the average particle size of the granulated composition, and even more preferably 1 times to 5 times the average particle size of the granulated composition. Preferably, the average size of the particles of the granulated composition comprising the high molecular weight processing aid is at least 10% of the average size of the particles of the polyvinyl chloride resin. For example, when the average particle size of the polyvinyl chloride resin is 20 mm, the average particle size of the particles comprising the high molecular weight processing aid is at least 2 mm. More preferably, the average size of the particles of the composition comprising the high molecular weight processing aid is at least 20% of the average size of the particles of the polyvinyl chloride resin. Even more preferably, the average size of the particles of the composition comprising the high molecular weight processing aid is at least 30% of the average size of the particles of the polyvinyl chloride resin, and still more preferably, the average size of the particles of the composition comprising the high molecular weight processing aid is at least 40% of the average size of the particles of the polyvinyl chloride resin. In certain embodiments, the particles of the granulated composition can have a size similar to the PVC, such as 80% to 120% of the average size of the particles of the polyvinyl chloride resin, or more preferably 90% to 110% of the average size of the particles of the polyvinyl chloride resin.

[0036] Preferably, the PVC composition comprises at least 25 wt% recycled PVC, based on the total weight of the polyvinyl chloride resin. More preferably, the PVC composition comprises at least 40 wt%, at least 50 wt%, at least 60 wt%, at least 70 wt%, or at least 80 wt% recycled PVC, based on the total weight of the polyvinyl chloride resin.

[0037] The polyvinyl chloride resin can also include pristine polyvinyl chloride resin, which can be present as a powder. When present, the pristine polyvinyl chloride resin is preferably present in a mixture with the recycled polyvinyl chloride resin. The mixture of polyvinyl chloride resin can include both a powder and particles of polyvinyl chloride resin. When such a mixture is used, a mixture of a powdered processing aid and particles of the granulated composition comprising the high molecular weight processing aid can be used. Alternatively, the processing aid can be provided solely by the particles of the granulated composition comprising the high molecular weight processing aid.

[0038] The present application also relates to articles made from polyvinyl chloride resin compositions having particles of the granulated composition comprising the high molecular weight processing aid according to the above embodiments.

[0039] Another aspect of the invention relates to a method for preparing a polyvinyl chloride composition, the method comprising blending a polyvinyl chloride resin with particles of a granulated composition comprising a high molecular weight processing aid. The particles of the granulated composition comprising the high molecular weight processing aid can be incorporated at a high concentration and are diluted into the bulk polyvinyl chloride resin during the extrusion process.

[0040] Examples

[0041] To prepare Examples 1 to 3, a high molecular weight processing aid SURECEL containing 100% by weight was prepared. ™ 467 (Dow Chemical Company) composition granules. SURECEL powder is compacted. ™ 467. Particles were prepared by breaking down the compacted powder to form particles with an average particle size (D50) of 2 mm. Control sample 1 was prepared from uncompacted powdered SURECEL. ™ 467 was prepared and used to determine the reduction in molecular weight. Paraaloid was used. ™ 445 Examples 4 through 6 and Control Sample 2 were prepared in a similar manner. Examples 1 and 4 were compacted at a pressure of 5 kSi, Examples 2 and 5 were compacted at a pressure of 25 kSi, and Examples 3 and 6 were compacted at a pressure of 30 psi.

[0042] The molecular weight of high molecular weight processing aids was determined using gel permeation chromatography (GPC). The GPC data are shown in Table 1 below.

[0043]

Claims

1. A granulating composition, said granulating composition comprising: A high molecular weight processing aid, wherein the high molecular weight processing aid is present in an amount ranging from 50% to 100% by weight relative to the total weight of the composition; and One or more additional components, selected from the group consisting of lubricants, heat stabilizers, antioxidants, fillers and colorants, wherein the one or more additional components are present in an amount ranging from 0% to 50% by weight relative to the total weight of the composition; The composition does not contain a carrier resin; and The composition is in particulate form, wherein the D50 particle size ranges from 1 mm to 30 mm and the d10 particle size is at least 50% of the D50 particle size.

2. The composition according to claim 1, wherein the high molecular weight processing aid is a polymer or copolymer comprising monomers selected from vinyl aromatics, (meth)acrylonitrile and (meth)acrylate monomers.

3. The composition according to claim 1 or 2, wherein the high molecular weight processing aid is a copolymer comprising an alkyl methacrylate monomer.

4. The composition according to claim 3, wherein the high molecular weight processing aid is a copolymer comprising methyl methacrylate and at least one monomer selected from alkyl acrylate monomers.

5. The composition according to claim 4, wherein the alkyl acrylate monomer is selected from ethyl acrylate, butyl acrylate or 2-ethylhexyl acrylate.

6. The composition according to any one of the preceding claims, wherein the high molecular weight processing aid has a weight-average molecular weight of at least 5,000,000 g / mol.

7. The composition according to any one of the preceding claims, wherein the high molecular weight processing aid has a weight-average molecular weight of at least 10,000,000 g / mol.

8. The composition according to any one of the preceding claims, wherein the high molecular weight processing aid is present in an amount ranging from 70% to 100% by weight relative to the total weight of the composition.

9. The composition according to any one of the preceding claims, wherein the high molecular weight processing aid is present in an amount ranging from 90% to 100% by weight relative to the total weight of the composition.

10. A polyvinyl chloride composition comprising a polyvinyl chloride resin and a composition according to any one of the preceding claims.

11. The polyvinyl chloride composition of claim 10, wherein the polyvinyl chloride resin comprises recycled polyvinyl chloride resin.

12. The polyvinyl chloride composition of claim 11, wherein the polyvinyl chloride resin comprises a blend of recycled polyvinyl chloride resin and virgin polyvinyl chloride resin.

13. The polyvinyl chloride composition according to any one of claims 11 or 12, wherein the recycled polyvinyl chloride resin is in granular form, and the average particle size of the granules ranges from 0.5 times to 10 times the average particle size of the granulated composition.

14. An article formed from the composition according to any one of claims 10 to 13.

15. A method for preparing a polyvinyl chloride composition, the method comprising blending a polyvinyl chloride resin with the composition according to any one of claims 1 to 9.

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