PLASTICIZED PVC COMPOSITIONS

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to plasticized PVC compositions, and, more particularly, to stable plasticized PVC compositions including a C4-C30 alkyl pyrrolidone present in an amount sufficient to plasticize PVC and impart flexibility, softness, extensibility and lower melting temperatures to the PVC.

2. Description of the Prior Art

It is well known in the prior art that addition of certain organic compounds, called plasticizers, to PVC confers on the PVC desirable properties such as flexibility, softness, good, feel and ease of processability, extensibility and lower melting temperature [Encyclopedia of PVC Vol. 1 and 2, L. I. Nass (1976)]. Plasticizers function by dissolving in PVC, reducing the cohesive energy density between the polymer chains and reducing the polar forces exerted by the halogen atoms present in PVC. For any organic compound to function as an effective plasticizer for PVC it (a) must possess very high miscibility with PVC, (b) must have polar groups and (c) must have a low tendency to diffuse and migrate out of the polymer during its effective service life. In addition, the plasticizer must not cause coloration to PVC, should be non-toxic, odorless, possess low volatility and be thermally stable at the temperature of mixing and compounding of PVC with the plasticizer.

A variety of organic compounds have been reported as effective plasticizers for PVC. These include esters of phthalic anhydride with aliphatic alcohols (linear/branched) with four to fifteen carbon atoms, epoxidized soyabean oil, esters of trimellitic acids, phosphates, esters of benzoic and citric acids, and halogenated hydrocarbons. Higher molecular weight polyesters (800-6000) prepared by condensation of diols with adipic or sebacic acids are also used as plasticizers. Of these, phthalate-based plasticizers are the most widely used because of their excellent compatibility with PVC, ease of fusion and all-around desirable properties.

Nevertheless, phthalate esters are not without drawbacks. Dioctylphthalate has been implicated as a carcinogen causing liver cancer in rats. Their low molecular weights enable them to diffuse out of PVC rapidly and cause "fogging" (cloudy deposits) on glass and other transparent surfaces. Also they are easily extracted by organic solvents, making them unsuitable for use in applications requiring solvent contact.

The prior art in the plasticizer field is typified by the following U.S. Patents and Published Applications: 5,777,014; 6,118,012; 6,706,815; 2004/0001948 and 2004/0198909.

U.S. Pat. 5,294,644 discloses surface active lactams which have particularly effective surfactant activity for active organic compounds such as agriculture chemicals and drugs. Many other interesting properties are attributed to such lactams including anti-stat, anti-block and lubricant properties. The particular utility for these lactams was its ability to form stable emulsion concentrates of water insoluble agricultural chemicals.

Accordingly, it is an object of this invention to provide long term plastification to PVC so as to impart flexibility, softness, extensibility and/or lower melting temperatures to PVC compositions.

Another object herein is to provide such plasticized PVC compositions for such applications as films, siding, sheets, pipe and tubing as well as calendered sheets, plastisols, foams and dispersions.

SUMMARY OF THE INVENTION

A stable, plasticized composition of PVC polymer includes a C ₄ -C ₃₀ linear, branched or cyclo-alkyl pyrrolidone present in an amount of 5-400 phr (parts per hundred of rubber) sufficient to plasticize said PVC into a flexible state.

Preferably, the composition includes a C ₆ -C _2O alkyl pyrrolidone present in an amount of at least 5 phr, preferably 5-400 phr, and most preferably 10-100 phr. Cs-Ci ₂ alkyl pyrrolidones which are liquid at room temperature are preferred for use herein.

The compositions of the invention provide PVC products characterized by a Shore A hardness value of < 100 to < 10 (semi rigid to extremely flexible).

The PVC product of the invention including the C ₄ -C ₃₀ alkyl pyrrolidone plasticized composition, alone or in combination with one or more primary or secondary plasticizers, suitably may be in the form of a calendered sheet, plastisol, foam or dispersion in a film, siding, pipe or tubing and the like.

DETAILED DESCRIPTION OF THE INVENTION

Suitable alkyl pyrrolidones for use as plasticizers in PVC compositions are C ₄ -C ₃₀ linear, branched or cyclo-alkyl pyrrolidones, preferably C ₆ -C ₂₀ alkyl pyrrolidones including cyclohexyl pyrrolidone, and, most preferably, liquid at room temperature, such as linear N-octyl (C ₈ ) pyrrolidone (NOP) and linear N-dodecyl (Ci ₂ ) pyrrolidone (NDP), which are commercially available as Surfadone ^® LP-100 and 300, respectively, sold by International Specialty Products (ISP). These Ce and C ₁₂ alkyl pyrrolidones perform effectively in an amount of at least 5 phr, preferably 5-400 phr, and, most preferably, 10-100 phr of the PVC. This amount is sufficient to plasticize the PVC into a flexible state. A blend with one or more primary or secondary plasticizers may be used. Suitably this amount of plasticizer will form advantageous plasticized

PVC in such diverse forms as calendared sheets, plastisols, foams and dispersions, in applications such as films, siding, pipe or tubing to impart flexibility, softness, extensibility and lower melting temperature to the PVC.

The examples which follow will more particularly illustrate the invention.

EXAMPLE 1

Typical PVC formulations according to the invention are given in Table 1 below.

TABLE 1

Vestolit ^® B 7021 (Vestolit Corp./Marl, Germany) is a S-PVC with a

K value of 70.

Vestinol ^® 9 is Diisononylphthalate (DINP).

A. Preparation of Calendered Sheets

Using Compositions of Table 1

Calendered sheets with the NOP and NDP formulations above were much softer and clearer than DINP. Sheets with NOP are most flexible; approximately twice as soft as the sheet with DINP. Also blends of DINP/NOP (3:1) and DINP/NDP (3:1) produced more flexible sheets then DINP alone at the same use level (60 phr).

B. Plastisols

Both NOP and NDP increased the viscosity of the plastisols indicating onset of gelation, and lowered its gelling temperature and increased the gelling. The higher alkyl pyrrolidone was more suitable for achieving long open times for plastisols.

C. Foams The following formulations shown in Table 2 below were used.

TABLE 2

* Profor ADC/L-C2 is a blowing agent based on azodicarbonamide. ** Lankomark LZK 125 is a mixed metal salt stabilizer.

Foaming was performed with these formulations at 200 ⁰ C. The resultant foam density (g/cm ³ , y-axis) versus foaming time (s, x-axis), results show that addition of Ce or C ₁₂ alkyl pyrrolidone produce foams of higher foam density and greater stability than DINP. The addition of higher amounts NOP and NDP in the composition resulted in more even and smoother surfaces.

D. Dispersions

2-8% NOP or NDP in aqueous PVC dispersions lowered the Minimum Film Building Temperature (MFT) from 14 ⁰ C to 2 ⁰ C, which is a significant reduction and a desirable result.

EXAMPLE 2 Plasticizing Efficiency of N-Dodecyl-2-Pyrrolidone

The following compositions shown in Table 3 below were used:

TABLE 3

* Solvin 271 PC is a S-PVC with K value of 71. ** Baerostab CT 9156X is a Ca/Zn stabilizer.

Calendered sheets of these compositions were tested for Shore Hardness A, tensile strength, elongation at break, and water absorption after 1 d and 7 d (days).

TABLE 4

* Test Method ASTM D-2240 ** Test Method ASTM D-412 *** Test Method ASTM D-42

The results in Table 4 show that invention formulations containing 40 phr NDP give a Shore Hardness A value that is equal to 60 phr Vestinol 9 (DINP), i.e. NDP is substantially more efficient than DINP in achieving a desired flexible PVC.

EXAMPLE 3

A. Reduced Gelling Temperatures

In NOP and NDP plasticized PVC compositions, PVC gelation occurs at 45 ⁰ C or lower.

B. Increased Gelling Speed

Plastification and gelation occurs faster with NOP and NDP plasticized PVC thus increasing production yield.

C. Elasticity

NDP is very efficient at producing highly elastic PVC at much lower use levels than with other plasticizers. With 100 phr NDP in PVC (K 70) a Shore A hardness of 40 is achievable.

The invention composition may be used effectively in such applications as insulations and jackets for wire and cable; liners for pools, ponds, landfill, irrigation trench; sheeting for waterbeds; fabric coating; carpet backing; automotive parts like dashboards, door panels, arm rests and other; car underbody coating; tiles; wall coverings; flooring sheets; packaging films; conveyor belts; tarpaulins; roofing membranes; electrical plug and connections; inflatable shelters; toys; garden hose; pipes and tubings; agricultural films; refrigerator and freezer gasketing; shoe soles and uppers, boots; fishing lures manufactured by using one of the state of the art technologies like calendaring, extrusion, plastisol, foam, dispersion.

While the invention has been described with particular reference to certain embodiments thereof, it will be understood that changes and modifications may be made which are within the skill of the art.