Description:TITLE OF THE INVENTION: A CHLORINATED POLY VINYL CHLORIDE COMPOUND
FIELD OF THE INVENTION
The present disclosure is generally related to a Chlorinated Poly Vinyl Chloride compound for pipes and fittings. Particularly, the present disclosure is related to a Chlorinated Poly Vinyl Chloride compound with improved static and dynamic thermal stability, which enhances the performance of pipes and fittings.
BACKGROUND OF THE INVENTION
In addition to other advantageous characteristics, Chlorinated Polyvinyl Chloride (CPVC) is well-known for its hot water application capability. There is usually an excess of 66% bound chlorine in CPVC. Because of its exceptional flame and smoke qualities, high glass transition temperature, high heat deflection temperature, and chemical inertness, CPVC is a significant specialty polymer.
In general, the more chlorine present, the higher the glass transition temperature of the CPVC. CPVC is also recognised to have low impact characteristics. However, the CPVC gets harder to process and more brittle as the chlorine concentration rises. The majority of efforts have focused on rigid CPVC applications, where it is essential to have appropriate impact strength and dimensional stability under heat.
When processing at elevated temperatures, the CPVC tends to deteriorate. There is a possibility that the CPVC will deteriorate because the processing temperature and the degradation temperature are often fairly close to one another. It is believed that halide acid produced during the processing of CPVC causes (or catalyses) degradation, attacking and perhaps corroding the processing equipment components.
A distinct compound is needed for CPVC resins due to their higher chlorine content than PVC. In order to protect the CPVC, stronger stabiliser formulations are needed, due to the requirement of higher processing temperatures for CPVC processing. Therefore, it is preferable to increase the static and dynamic thermal stability of the CPVC compound.
The processing of conventional CPVC compound with tin stabilizer is a cumbersome process because of the early degradation of the CPVC resin at elevated temperatures. Improving the processing requires high concentration of tin stabilizer; this is not only expensive, but also affects product performance.
There is, therefore, a need in the art, for a Chlorinated Poly Vinyl Chloride compound, which overcomes the aforementioned drawbacks and shortcomings.
SUMMARY OF THE INVENTION
A Chlorinated Poly Vinyl Chloride (CPVC) compound with improved static and dynamic thermal stability, which enhances the performance of pipes and fittings, is disclosed. Said CPVC compound broadly comprises: a Chlorinated Poly Vinyl Chloride resin; an organotin stabilizer; a pigment; lubricants; an impact modifier; a processing aid; and an acid scavenger.
The CPVC resin contains about 57% by weight to about 70% by weight (wt%) of chlorine. Said CPVC resin is in a concentration of about 100 parts.
Said organotin stabilizer is in a concentration that ranges between about 1 part per hundred resin (phr) and about 5 parts per hundred resin.
Said pigment is in a concentration that ranges between about 2 parts per hundred resin and about 5 parts per hundred resin.
Said lubricants are in a concentration that ranges between about 0.5 parts per hundred resin and about 5 parts per hundred resin.
Said impact modifier is in a concentration that ranges between about 4 parts per hundred resin and about 10 parts per hundred resin.
Said processing aid is in a concentration that ranges between about 1 parts per hundred resin and about 4 parts per hundred resin.
Said acid scavenger is in a concentration that ranges between about 2 parts per hundred resin and about 3 parts per hundred resin.
The disclosed CPVC compound offers at least the following synergistic advantages and effects: requires low concentration of the tin stabilizer; can easily be processed without scorching (uniform surface appearance of pipes and fittings) by avoiding the scorch that improves the aesthetic look; and/or improves both static and dynamic thermal stability.
BRIEF DECRIPTION OF THE DRAWINGS
Figure 1 illustrates the results of thermal stability with Brabender Torque Rheometer, in accordance with the present disclosure; and
Figure 2 illustrates the results of colour stability with Brabender Torque Rheometer, in accordance with the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
Throughout this specification, the use of the words “comprise” and “include”, and variations, such as “comprises”, “comprising”, “includes”, and “including”, may imply the inclusion of an element (or elements) not specifically recited. Further, the disclosed embodiments may be embodied, in various other forms, as well.
Throughout this specification, the words “the” and “said” are used interchangeably.
Throughout this specification, the terms “Chlorinated Poly Vinyl Chloride” and “CPVC” are used interchangeably.
Throughout this specification, the disclosure of a range is to be construed as being inclusive of: the lower limit of the range; and the upper limit of the range.
Also, it is to be noted that embodiments may be described as a method. Although the operations, in a method, are described as a sequential process, many of the operations may be performed in parallel, concurrently, or simultaneously. In addition, the order of the operations may be re-arranged. A method may be terminated, when its operations are completed, but may also have additional steps.
A Chlorinated Poly Vinyl Chloride compound (also referred to as “CPVC compound”) with improved static and dynamic thermal stability, which enhances the performance of pipes and fittings, is disclosed. In an embodiment of the present disclosure, said CPVC compound broadly comprises: a Chlorinated Poly Vinyl Chloride (CPVC) resin; an organotin stabilizer; a pigment; lubricants; an impact modifier; a processing aid; and an acid scavenger.
In another embodiment of the present disclosure, the CPVC resin contains about 57% by weight (wt%) to about 70% by weight of chlorine.
In yet another embodiment of the present disclosure, the CPVC resin contains about 60% by weight to about 69% by weight of chlorine.
In yet another embodiment of the present disclosure, the CPVC resin contains about 63% by weight to about 68% by weight of chlorine.
In yet another embodiment of the present disclosure, the CPVC resin contains about 64% by weight to about 67% by weight of chlorine.
In yet another embodiment of the present disclosure, the CPVC resin contains about 66% by weight of chlorine.
The weight percentage of chlorine is determined based on the weight of the CPVC resin.
In yet another embodiment of the present disclosure, the concentration of the CPVC resin is about 100 parts.
In yet another embodiment of the present disclosure, the concentration of the organotin stabilizer ranges between about 1 part per hundred resin (phr) and about 5 parts per hundred resin. The concentration varies depending on the organotin stabilizer used.
In yet another embodiment of the present disclosure, the organotin stabilizer includes, but is not limited to: alkyl tin mercaptides (methyl, butyl, or octyl); alkyl tin carboxylate; alkyl tin maleate; and/or a composition of mono and dialkyl tin (2-ethyl hexyl mercapto acetate).
In yet another embodiment of the present disclosure, the concentration of the organotin stabilizer ranges between about 2 phr and about 4 phr.
In yet another embodiment of the present disclosure, the concentration of the pigment ranges between about 2 phr and about 5 phr; for example, said concentration ranges between about 2 phr and about 4 phr.
In yet another embodiment of the present disclosure, the pigment is rutile or anatase titanium dioxide with silica – alumina treatment.
In yet another embodiment of the present disclosure, the concentration of the lubricants ranges between about 0.5 phr and about 5 phr.
In yet another embodiment of the present disclosure, the lubricants include, but are not limited to: montan wax; fatty acid esters; purified or hydrogenated natural or synthetic triglycerides or partial esters; polyethylene waxes; amide waxes; chloro-paraffins; glyceryl esters or alkaline earth metal soaps; Fischer-Tropsch wax; and/or oxidized polyethylene wax.
In yet another embodiment of the present disclosure, the concentration of the impact modifier ranges between about 4 phr and about 10 phr.
In yet another embodiment of the present disclosure, the impact modifier includes, but is not limited to: poly acrylic resins; butadiene-containing polymers such as methyl methacrylate butadiene styrene (MBS); chlorinated polyethylene (CPE) resins; poly acrylates including (C4-C12) acrylate homo or copolymers; second stage graft copolymerized with methyl methacrylate and styrene; poly(ethyl hexyl acrylate-co-butyl-acrylate) graft copolymerized with styrene and/or acrylonitrile and/or methyl methacrylate; and/or poly butyl acrylate graft polymerized with acrylonitrile.
In yet another embodiment of the present disclosure, the concentration of the processing aid ranges between about 1 phr and about 4 phr.
In yet another embodiment of the present disclosure, the processing aid includes, but is not limited to: acrylic polymer; high molecular weight Methyl Methacrylate (MMA) copolymers (MMA/styrene); and/or Acrylonitrile styrene.
In yet another embodiment of the present disclosure, the processing aid comprises only methacrylate having an excellent compatibility with a vinyl chloride resin, or a methyl methacrylate-based polymer composed of methyl methacrylate monomer as a main component and a high molecular weight (500,000 g/mole to 5,000,000 g/mole) polymer, as an auxiliary component, obtained by emulsion-copolymerization.
In yet another embodiment of the present disclosure, the concentration of the acid scavenger ranges between about 2 phr and about 3 phr.
In yet another embodiment of the present disclosure, the acid scavenger is sodium aluminosilicate with a particle size that ranges between about 2 µm and about 5 µm.
Said sodium aluminosilicate comprise a three-dimensional framework of SiO4 tetrahedra and AlO4 octahedra. The tetrahedra are cross-linked by splitting oxygen atoms, so that the ratio of oxygen atoms to the total aluminum and silicon atoms is equal to 2. The spaces between the tetrahedra of the aluminosilicate zeolite are usually occupied by water. Zeolites can be either natural or synthetic. The basic formula for all aluminosilicate zeolites is represented as follows: M2 / n O: [Al2O3] x : [SiO2] y : [H2O] z where M represents a metal, n represents the valency of the metal, and X, Y, and Z vary for each particular aluminosilicate zeolite.
The above CPVC compound is recommended for use in manufacturing of CPVC pipes and fittings.
The below tables illustrate the disclosed CPVC compound with three different compositions of ingredients (Example 1, Example 2, and Example 3) and a Control CPVC compound.
S. No Ingredient Concentration in Parts Per Hundred Resin (phr)
Control Example 1 Example 2 Example 3
1 CPVC Resin 100 100 100 100
2 Alkyl Tin Mercaptide Stabilizer 2.5 2.5 2.5 2.5
3 Rutile Titanium Dioxide Pigment 3.0 3.0 3.0 3.0
4 Methyl Methacrylate Butadiene Styrene Impact Modifier 5.6 5.6 5.6 5.6
5 Acrylic Processing Aid 2.0 2.0 2.0 2.0
6 Oxidized Polyethylene (OPE) Wax 2.6 2.6 2.6 2.6
7 Fischer-Tropsch Wax 0 0.7 0 0.7
8 Sodium Aluminosilicate 0 0 2.0 2.0

S. No Ingredient Concentration in Parts Per Hundred Resin (phr)
Control Example 1 Example 2 Example 3
1 CPVC Resin 100 100 100 100
2 Alkyl Tin Mercaptide Stabilizer 2 - 5 2 - 5 2 - 5 2 - 5
3 Rutile Titanium Dioxide Pigment 2 - 4 2 - 4 2 - 4 2 - 4
4 Methyl Methacrylate Butadiene Styrene Impact Modifier 4 - 10 4 - 10 4 - 10 4 - 10
5 Acrylic Processing Aid 1 - 4 1 - 4 1 - 4 1 - 4
6 Oxidized Polyethylene (OPE) Wax 2 - 4 2 - 4 2 - 4 2 - 4
7 Fischer-Tropsch Wax 0 0.6 - 0.8 0 0.6 - 0.8
8 Sodium Aluminosilicate 0 0 2 - 3 2 - 3

In yet another embodiment of the present disclosure, the CPVC resin, the stabilizer, and the other ingredients are put into a hot mixer and mixed them by rotating at a speed that ranges between about 600 rpm and about 700 rpm. After about 6 to about 10 minutes, the temperature of mixer reaches about 120°C; then the batch is discharged into a cold mixer (about 6 to about 10 mins) for premixing.
Thermal stability analysis
Static thermal stability analysis was performed by Congo Red (CR) test according to the ISO 182-1-1990 standard. The temperature-controlled oil bath was heated to 180°C. The CPVC compound sample placed in a closed test tube, which was put into the oil bath until the strip of CR paper placed at the top of the tube changed from red to blue. The time required for the colour change is referred as the stability time.
The dynamic thermal stability was performed for said compounds in the Brabender torque rheometer at 190°C and 35 rpm. The pre-mixed sample was prepared by mixing all ingredients as listed above in a high-speed mixer to 120°C and then cooling to 50°C. The test procedure used was to remove the specimen from the rheometer head after 15 minutes and then assess them for colour stability. The thermal stability was also determined by change in colour of extrudate compound due to degradation, which was observed by the increase in torque.
The test results of static thermal stability of the CPVC compound by Congo red test are provided in the below table.
Test Static Thermal Stability in Minutes
Control Example 1 Example 2 Example 3
Static Thermal Stability 42 43 46 50

The results of the thermal stability and colour stability of the control and three examples of the disclosed CPVC compound are illustrated in Figure 1 and Figure 2, respectively. From the results, it is observed that the control and Example 2 give higher operating torque and frictional heat, and cause scorching of the extrudate compound. In Example 1, by the addition of the Fischer-Tropsch wax, the operating torque and the frictional heat were controlled. In the Example 3, it can be seen that the sodium aluminosilicate scavenges the halide acid liberated during operation at elevated temperatures and the Fischer-Tropsch wax helps to control the torque as well as frictional heat; as a result, significant improvements were observed.
The disclosed CPVC compound offers at least the following synergistic advantages and effects: requires low concentration of the tin stabilizer; can easily be processed without scorching (uniform surface appearance of pipes and fittings) by avoiding the scorch that improves the aesthetic look; and/or improves both static and dynamic thermal stability.
It will be apparent to a person skilled in the art that the above description is for illustrative purposes only and should not be considered as limiting. Various modifications, additions, alterations, and improvements, without deviating from the spirit and the scope of the disclosure, may be made, by a person skilled in the art. Such modifications, additions, alterations, and improvements should be construed as being within the scope of this disclosure.
, Claims:1. A Chlorinated Poly Vinyl Chloride compound with improved static and dynamic thermal stability, which enhances the performance of pipes and fittings, comprising:
a Chlorinated Poly Vinyl Chloride resin, with concentration of said Chlorinated Poly Vinyl Chloride being 100 parts, with:
said CPVC resin containing 57% by weight to 70% by weight of chlorine;
an organotin stabilizer, with concentration of said organotin stabilizer ranging between 1 part per hundred resin and 5 parts per hundred resin;
a pigment, with concentration of said pigment ranging between 2 parts per hundred resin and 5 parts per hundred resin;
lubricants, with concentration of said lubricants ranging between 0.5 parts per hundred resin and 5 parts per hundred resin;
an impact modifier, with concentration of said impact modifier ranging between 4 parts per hundred resin and 10 parts per hundred resin;
a processing aid, with concentration of said processing aid ranging between 1 part per hundred resin and 4 parts per hundred resin; and
an acid scavenger, with concentration of said acid scavenger ranging between 2 part per hundred resin and 3 parts per hundred resin.
2. The Chlorinated Poly Vinyl Chloride compound with improved static and dynamic thermal stability, which enhances the performance of pipes and fittings, as claimed in claim 1, wherein:
the organotin stabilizer is: an alkyl tin mercaptide (methyl, butyl or octyl), alkyl tin carboxylate, alkyl tin maleate, or a composition of mono and dialkyl tin (2-ethyl hexyl mercapto acetate)
3. The Chlorinated Poly Vinyl Chloride compound with improved static and dynamic thermal stability, which enhances the performance of pipes and fittings, as claimed in claim 1, wherein:
the pigment is rutile or anatase titanium dioxide with silica - alumina treatment.
4. The Chlorinated Poly Vinyl Chloride compound with improved static and dynamic thermal stability, which enhances the performance of pipes and fittings, as claimed in claim 1, wherein:
the lubricants include: montan wax; fatty acid esters; purified or hydrogenated natural or synthetic triglycerides or partial esters; polyethylene waxes; amide waxes; chloro-paraffins; glyceryl esters or alkaline earth metal soaps; Fischer-Tropsch wax; and oxidized polyethylene wax.
5. The Chlorinated Poly Vinyl Chloride compound with improved static and dynamic thermal stability, which enhances the performance of pipes and fittings, as claimed in claim 1, wherein:
the impact modifier is: a poly acrylic resin; a butadiene-containing polymer; a poly acrylate; a second stage graft copolymerized with methyl methacrylate and styrene; a poly(ethyl hexyl acrylate-co-butyl-acrylate) graft copolymerized with styrene, acrylonitrile, and methyl methacrylate; or a poly butyl acrylate graft polymerized with acrylonitrile and styrene.
6. The Chlorinated Poly Vinyl Chloride compound with improved static and dynamic thermal stability, which enhances the performance of pipes and fittings, as claimed in claim 1, wherein:
the processing aid is: an acrylic polymer; a high molecular weight Methyl Methacrylate (MMA) copolymer; or Acrylonitrile styrene.
7. The Chlorinated Poly Vinyl Chloride compound with improved static and dynamic thermal stability, which enhances the performance of pipes and fittings, as claimed in claim 1, wherein:
the acid scavenger is sodium aluminosilicate with a particle size that ranges between 2 µm and 5 µm.