New benzoate plasticizers for polyvinyl chloride: Introduction and performance example

Two new unique benzoate ester plasticizers that will offer the vinyl formulator improved performance have been developed. One is an excellent solvator that will yield lower plastisol viscosities than existing plasticizers. The other will provide an excellent alternate with low volatility. The new products provide expanded performance utility over existing benzoates and phthalates on a global basis. Basic plastisol performance data and an example of use in a specific application, vinyl leathercloth, are presented. The data demonstrates that these blends are compatible, effective high solvating plasticizers and are performance alternates for plastisols and other polyvinyl chloride applications.     

Plasticizer structure/performance relationships

Plasticizers for poly(vinyl chloride) may be organized into eight chemical families and by seven key performance criteria. Cost-effective general-purpose phthalates provide a base line for comparing all other plasticizers. The wide range of performance characteristics associated with various phthalate isomers substantiates the large proportion of phthalate esters that are utilized as plasticizers. This article summarizes plasticizer structural/performance relationships using quantitative comparisons of cost, plasticizing efficiency, plastisol solvation characteristics, dryblending, volatility, and low temperature performance properties in PVC. Some generalizations are also made concerning structural effects of the alcohol isomers used in the syntheses of the various types of plasticizer esters.     

Unique benzoate plasticizer for reducing viscosity and fusion temperature

Plastisol viscosity reduction and control is an important property specification in many vinyl plastisol formulations. A unique benzoate plasticizer is under development that functions as a viscosity reducer. It also is a highly solvating plasticizer in standard plastisol systems. Data are presented on the effects of the new benzoate plasticizer on the properties of phthalate‐ and benzoate‐containing plastisols and vinyl sheet.     

New dibenzoate plasticizer blends for PVC applications

Dibenzoates plasticizers are well‐established and are used in PVC applications. Chemically, these plasticizers are non‐phthalates and function well as high‐solvating. In the past, new benzoates, dibenzoate blends, and grades were developed to keep pace with formulators' needs. More recently, a new generation of dibenzoate triblend platform has been developed to offer formulators an improved high solvator to complement general purpose plasticizer performance. A basic plastisol evaluation protocol was utilized to help determine how to formulate with these new blends. In addition to the basic data that were developed, examples of performance in starting plastisol formulations are shown. J. VINYL ADDIT. TECHNOL., 20:137–142, 2014. © 2014 Society of Plastics Engineers     

Rheometric study of the gelation and fusion processes of poly(vinyl chloride‐co‐vinyl acetate) plastisols with different commercial plasticizers

Evolution of the complex viscosity of pastes of PVC‐VA (vinyl chloride‐vinyl acetate copolymer) plasticized with different commercial plasticizers has been studied. Knowledge of the rheological behavior of the formulations allows for better understanding of the gelation and fusion processes. Twenty commercial plasticizers of different types and with different functional groups have been studied and are grouped into five families: phthalate esters with linear chains, phthalate esters with branched chains, adipates (normal and polymeric), citrates, and rest of the plasticizers (carboxylates, alkylsulfonates, and pentaerythritol ester derivatives). Interesting relationships among the observed rheologies and the nature and molecular weight of the plasticizer have been observed. The evolution of the complex viscosity with temperature—at the temperatures where the blowing agents normally used in PVC plastisol foaming processes generate the main amount of gas—has been newly discussed with regard to the chemical structure and molecular weight of all of the plasticizers used. It was found that several different dynamic processes must be synchronized in order to understand the relationships among the chemical structure, plasticization, plasticizer compatibility, rheological properties, and foaming process of such materials. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

Enhancing the performance of flexible vinyl by using the formulary approach

Each vinyl plastisol processor has different requirements. The features of the finished goods determine the specifications and physical properties that are critical in the manufacturing process. Processors may also have varying equipment limitations that require a specific working range of each plastisol property, such as viscosity, for acceptable processing. Although the benzoate esters have been utilized for many years by plastisol formulators and processors to their advantage, usage of these esters has been limited because of their tendency to yield high‐viscosity plastisols. By utilizing a formulary approach, it is possible to fine‐tune the properties of the plastisol, thus allowing greater latitude. Design of experiment (DOE) was employed to accomplish this objective. For this work, generic resilient‐flooring formulations were selected as the model. The formulary approach was employed to adjust the formulation and processing parameters, thereby allowing plastisol formulators and processors to develop cost‐efficient formulations. J. VINYL ADDIT. TECHNOL., 13:201–205, 2007. © 2007 Society of Plastics Engineers     

Recent developments: Benzoate esters in polyvinyl resilient flooring

Benzoate plasticizers provide excellent foam quality, stain resistance, and UV light stability. They are used as primary plasticizers in resilient flooring applications but are limited in use because of viscosity. New benzoate-based blends have been developed that result in reduced-viscosity plastisols and lower VOC emissions than for existing benzoate products. A variety of European and North American formulations have been used to evaluate the processing and performance properties of these benzoate-based blends and are highlighted in this paper.     

The effects of plasticizers on the properties of poly(vinyl chloride) foams

The effects of plasticizers on poly(vinyl chloride) (PVC) plastisol mixtures were investigated. The investigations were carried out by determining the density of the PVC foam obtained by gelling the plastisol, as well as its elasticity and degree of expansion. Two series of experiments using different types of PVC were performed, using eight plasticizers, individually or as mixtures. Two-component plasticizer mixtures showed better properties than single-component plasticizers, and mixtures of di-iso-heptyl phthalate (DiHP) and butyl benzyl phthalate (BBP) proved to be the most appropriate. The effect of plasticizer amount also was investigated, and of the three parameters studied, the foam density, which steadily increased with plasticizer amount, was the critical one. It was also shown that in order to obtain consistent results, the foam expansion had to be precisely timed and the temperature carefully chosen.     

Trimethylpentanediol dibenzoate: New plasticizer for plastisol screen ink

Trimethylpentane diol (TMPD) dibenzoate use in vinyl as a plasticizer is not well recognized, and little has been published on vinyl performance characteristics. To assess new applications for vinyl, a basic evaluation was conducted. Based on the results of the screen and other considerations an evaluation for utility in plastisol silk screen ink was conducted. The results indicated that the TMPD dibenzoate performed very well in white ink, requiring good fabric dye bleed resistance compared to polymeric and phthalates currently being used for non-bleed ink. Non-bleed characteristics are important for colored tee shirt printing. The benzoate is a good solvator and has excellent extraction resistance.     

Viscosity aging of poly(vinyl chloride) plastisol: The effect of the resin type and plasticizer type

The viscosity of freshly prepared poly(vinyl chloride) (PVC) plastisol increases with time, and this phenomenon is called viscosity aging. The increase is rapid in the beginning and slows down to a quasistable value, but a very slow increase continues. The phenomenon may be a result of either the deagglomeration of agglomerated particles or the dissolution of low‐molecular‐weight PVC into the plasticizer. In this work, two typical commercial resins were used, one containing friable agglomerates and the other containing nonfriable agglomerates. With the friable‐agglomerate resin, about 40% of the initially present agglomerates deagglomerated, whereas the viscosity increased in a week to twice the initial value. With the nonfriable‐agglomerate resin, very fine and very low molecular weight particles, about 3% of all the particles, dissolved into the plasticizer in 2 days. The effect of the plasticizer type on the viscosity aging through deagglomeration was investigated with four plasticizers and three plasticizer blends. The emulsifiers used for polymerization, and retained through drying, affected the aging in the beginning. On the other hand, the viscosity after 1 week was free from the effect of the emulsifier and was affected only by the plasticizer type. With the exception of two blends, the 1‐week viscosity was quantitatively related to the dielectric constant divided by the molecular weight of the plasticizer. For the plasticizer blends, one of the plasticizers could have a dominant effect on the promotion of deagglomeration. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 448–464, 2005     

Effect of plasticizer type on gelation and fusion of PVC plastisol,dialkyl phthalate series

Different grades of PVC resins and a variety of plasticizers are used to adjust processability and properties of plastisol. The plastisol, which is a dispersion of fine particles of PVC in plasticizer, is coated on a substrate and heated in an oven to gel and fuse. In the gelation stage the resin particles become swollen with plasticizer and then, in the fusion stage the entire system fuses to become one homogeneous phase. The finished products are flexible PVC such as coated fabrics and surgical globes. Different plasticizers, because of the difference in solvent power, affect the process of gelation and fusion, and hence, processability. This paper examines such an effect systematically by employing a homologous series of plasticizers, dialkyl phthalates. The progress of gelation and fusion are followed by the measurements of dynamic moduli and by the observation with a scanning electron microscope. As it may be expected, the shorter the alkyl chain, the higher the solvent power of the plasticizer.     

Soft PVC foams: Study of the gelation,fusion, and foaming processes. I. Phthalate ester plasticizers

The use of foamed plastics gains more and more interest every day. Flexible poly(vinyl chloride) (PVC) foams have excellent mechanical properties and low price, thus their application is extensive. Foams are produced from plastisols, which are based on the suspension of the PVC resin in a plasticizer. Phthalates are the most used plasticizers in flexible PVC foam formation. In this study, we have studied the influence of the phthalate ester‐type plasticizers on the foaming process and the quality of the foams obtained from the corresponding plastisols. For the plastisols prepared with the nine phthalate plasticizers considered, we have studied and discussed the complex and extensional viscosities; the thermal behavior (DSC) including the decomposition of the chemical blowing agent, and the foam production by rotational molding. In addition, we have characterized the foams obtained by thermomechanical analysis, density, and bubble size distribution. As expected, clear correlations have been obtained between the molecular weight and structure of the plasticizer with the rheological behavior of the plastisols. The knowledge of the gelation and fusion processes and evolution of the extensional viscosity of the plastisols combined with the study of the thermal decomposition of the blowing agent in each plastisol allows for better understanding of the complex dynamic behavior of these foaming systems. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Revisiting analysis of phthalate plasticizers concentration in poly(vinyl chloride)

The method of the efficient analysis of di(2‐diethylhexyl) phthalate, tri(2‐ethylhexyl) trimellitate, di(2‐ethylhexyl) terephthalate, and other phthalate plasticizers concentrations in plasticized poly(vinyl chloride) (PVC) was developed. The method is based on quantitative dissolution of the PVC sample in methyl ethyl ketone with the consequent precipitation of PVC with hexane and concentration of phthalate in an organic layer. A capillary column‐based gas chromatographic technique for phthalates separation and quantification was developed and used in conjunction with the PVC and phthalates dissolution technique. The developed method of phthalate plasticizers analysis proved to be relatively fast, reproducible, and straightforward. J. VINYL ADDIT. TECHNOL., 21:197–204, 2015. © 2014 Society of Plastics Engineers     

Oligomeric isosorbide esters as alternative renewable resource plasticizers for PVC

Oligo(isosorbide adipate) (OSA), oligo(isosorbide suberate) (OSS), and isosorbide dihexanoate (SDH) were synthesized and evaluated as renewable resource alternatives to traditional phthalate plasticizers. The structure of the synthesized oligomers was confirmed by nuclear magnetic resonance spectroscopy (¹H‐ and ¹³C‐NMR), and molecular weight was determined by size exclusion chromatograph. The plasticizers were blended with poly(vinyl chloride) (PVC), and the miscibility and properties of the blends were evaluated by differential scanning calorimetry, fourier transform infrared spectroscopy, tensile testing, and thermogravimetry. Especially the blends plasticized with SDH had almost identical properties with PVC/diisooctyl phthalate (DIOP) blends. The blends containing OSA and OSS plasticizers, based on dicarboxylic acids, had somewhat lower strain at break but higher stress at break and better thermal stability compared to the PVC/DIOP or PVC/SDH blends. All the synthesized isosorbide plasticizers showed potential as alternative PVC plasticizers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Castor Epoxy Fatty Acid Alkyl Ester Estolides as Bioplasticizers for Poly(Vinyl Chloride)

Epoxy fatty acid alkyl ester estolides were synthesized from castor oil to be used as biobased plasticizers for poly(vinyl chloride) (PVC) as a safer replacement for phthalate plasticizers. Initially, castor oil was transesterified with methanol or n-butanol to quantitatively yield castor fatty acid alkyl esters. Acetylation of hydroxyl function with acetic anhydride led to the formation of estolide. The unsaturation was epoxidized, resulting in a bifunctional epoxy fatty acid alkyl ester estolide. The bioplasticizers were compounded with PVC and were evaluated for their functionality and compared with commercial phthalate plasticizer diisononyl phthalate (DINP) and nonphthalate 1,2-cyclohexanoic acid diisononyl ester (DINCH). The bioplasticizers showed excellent gelation, efficiency, and compatibility, as well as plastisol viscosity and thermal properties, comparable to or better than the plastisols prepared with commercial controls DINP and DINCH. The volatility of the methyl ester was inferior to the butyl ester. Both compounds showed low water resistance properties. Further evaluation of the butyl ester under tropical conditions of high temperature and humidity confirmed limited compatibility. This indicates that the castor epoxy fatty acid ester estolides would be better suited for applications that do not come in contact with water for prolonged periods, such as flooring, artificial leather, wiring, or wall coverings.     

Soft PVC foams: Study of the gelation,fusion, and foaming processes. II. Adipate,citrate and other types of plasticizers

Plasticized poly(vinyl chloride) (PVC) is one of the most useful polymeric materials on an industrial scale because of its processability, wide range of obtainable properties, and low cost. PVC plastisols are used in the production of flexible PVC foams. Phthalates are the most used plasticizers for PVC, and in a previous article (part I of this series), we discussed the influence of phthalate ester type plasticizers on the foaming process and on the quality of the foams obtained from the corresponding plastisols. Because the use of phthalate plasticizers has been questioned because of possible health implications, the objective of this work was to undertake a similar study with 11 commercial alternative plasticizers to phthalates. The evolution of the dynamic and extensional viscosity and the interactions and thermal transitions undergone by the plastisols during the heating process were studied. Foams were obtained by rotational molding and were characterized by the determination of their thermomechanical properties, density, and cell size distribution. Correlations were obtained between the molecular weight and structure of the plasticizer and the behavior of the corresponding plastisols. After the characterization of the final foamed product, we concluded that foams of relatively good quality could be prepared with alternative plasticizers for replacing phthalates. Several plasticizers {Mesamoll (alkylsulfonic phenyl ester), Eastman 168 [bis(2‐ethylhexyl)‐1,4‐benzenedicarboxylate], Hexamoll [di(isononyl) cyclohexane‐1,2‐dicarboxylate], Citroflex A4 acetyl tributyl citrate (ATBC), and Plastomoll (dihexyl adipate)} were found to be interesting alternatives in the production of soft PVC foams because they provided very good quality foams with properties similar to, or even better than, those obtained with phthalate plasticizers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Performance of Di-n-Hexyl phthalate in flexible vinyl formulations

Low-molecular-weight esters have been available to the PVC compounder for many years. They have found a significant niche in the performance vs. permanence compromise as a compound ingredient that provides manufacturing efficiency or some special property with adequate permanence for many vinyl applications. In many respects, low-molecular-weight esters are the processing aids of the plasticizer family. This group of plasticizers may be said to include C₄ to C₇ dialkyl phthalates, the benzyl phthalates and the benzoic acid esters. This paper will introduce and compare di-n-hexyl phthalate (DNHP) to other phthalates against which it will directly compete.     

Meaningful evaluation of plastisol gelation and fusion temperatures by dynamic mechanical analysis

In most PVC plastisol processing operations, gelation and fusion characteristics of the plastisol are critically important. For example, in chemically foamed plastisols, plastisol fusion temperature and blowing agent decomposition temperature must be carefully coordinated. In rotomolded parts, rates of gelation may determine the quality of the finished parts. For plastisol products made by any process, the final fusion temperature determines the processing temperatures required to give the finished product acceptable mechanical properties. For a variety of reasons, the methods commonly used to characterize plastisol gelation and fusion (hot bar test, resin in plasticizer clear point, torque rheometer measurements, etc.) provide comparisons between plastisols but do not provide temperatures that are easily related to actual industrial processes. With dynamic mechanical analysis (DMA), one can characterize, under low shear conditions, the temperatures at which gelation begins, gelation ends, and complete fusion occurs. Additionally, it is possible to record plastisol viscosities (and other dynamic mechanical properties) over the processing temperature range. We used a multiple linear regression program to analyze the DMA data for plastisols heated from 30 to 210°C and containing either 70, 80 or 90 phr of Jayflex dihexyl phthalate (DHP) or Jaylflex di-isodecyl phthalate (DIDP). Further, we determined the plasticizer phr dependence and the reproducibility of gel and fusion temperatures given by data analyzed in this manner. Finally, for comparison, we analyzed the reproducibility of initial and final plastisol gel temperatures and fusion temperatures, which were determined by visually analyzing the DMA data for plastisols containing 70, 80, and 90 phr of Jyflex plasticizers DHP, Jayflex 77, diisononyl phthalate (DINP), and DIDP. Precise characterization of plastisol gelation and fusion behavior will, undoubtedly, facilitate substitution of plastisol ingredients as is often required by those who manufacture and process plastisols.     

Effect of silicone oil on PVC plastisols

Surface defects in the form of craters have been a sporadic problem for manufacturers of films and coatings made from PVC plastisols. Examination and analysis of plastisols and films from two manufacturers have led to the conclusion that frequently such defects are caused by contamination of one or more of the plastisol components by silicone oil. Silicone oil is immiscible in commonly used plasticizers such as dioctyl phthalate (DOP) and can coalesce in mixing vats or pick up reservoirs to form droplets or pools of oil on the surface of the plastisol. Distribution of the droplets onto the substrate with the plastisol can cause craters to form when the oil dissipates into the melt during fusion.     

Plasticizer effects on vinyl extrusion efficiency

The choice of plasticizer for extrusion of flexible vinyl profiles is usually made for product performance properties. This paper deals with plasticizer influence on the entire extrusion process from dry-blend preparation to final extruded profile. Undestanding the effect of plasticizer throughout the extrusion line helps the compounder optimize for higher production rates, lower energy input, improved profile quality and better final physical properties. This study focused on the effect of low molecular weight, fast fusing plasticizers in the extrusion processing of general purpose formulations. Butyl benzyl phthalate was used as partial replacement for dialkyl phthalates. A positive influence of this replacement was observed in dry-blend preparation, in the compound extrusion step, in the finished extrusion step and in final product quality.