BACKGROUND OF THE INVENTION The nucleating agents are used to facilitate the crystallization of semi-crystalline polyolefin resins, leading the melted polymer when subjected to cooling to crystallize at a temperature higher than usual, increasing the rate of formation of the crystals and reducing the size of the crystals formed in the crystallization of those resins. In this manner, optical properties such as transparency and glossiness, in addition to mechanical properties such as rigidity and tensile strength are substantially enhanced. In general the effects provided by said nucleating agents are maximized when the melt temperature thereof is lower than the resin processing temperature, due to their higher dissolution and dispersion in the resin in this condition.

The products derived from sorbitol are at present widely used as nucleating agents, but their cost is very high. These products also evidence

difficulty to disperse in the resin due to the high melt point thereof.

An alternative found to solve these problems was based on the use of a crystal derived from rosin, a natural resin found in pine trees, as a nucleating and clarifying agent.

The various types of rosin found in the market are not appropriate for use as nucleating agents. It is necessary to modify the structure thereof in order to allow the same to be used effectively. This modification includes a process of partial neutralization of the carboxylic groups of the resinous acids present in the rosin, in a liquid medium, generally alcoholic, under stirring, for a certain time and at an adequate temperature.

Processes for production of rosin-based nucleating agents and applications thereof are described in US Patents Nos. 5, 856, 386 and 5,998, 576.

US Patent No. 5, 856, 386 describes and claims a process for improving the crystallization of thermoplastic resins using mixtures of acids and salts derived from rosin, particularly dehydroabietic acid, dihydroabietic acid and dihydropimaric acid. This patent briefly describes the process of preparation of modified rosin using two methods, using organic solvents, with or without water, as diluents. The operating temperatures of this preparation are in the range from 40 to 150°C and the solvent is removed by distillation. No details are disclosed regarding the presence of contaminants from the rosin or the final color of the product obtained.

US Patent No. 5,998, 576 describes and claims crystals formed by

acids and salts derived from rosin, particularly dehydroabietic acid, a nucleating agent based on these crystals, the application thereof in polyolefins and the molded article resulting from the application thereof. This patent describes the process of preparation of said crystals using two methods, the first using an alcoholic solvent and performing the reaction at temperatures above ambient temperature and the crystallization at temperatures above 30°C, employing the principle of crystallization by evaporation. The second method is a melting method, where the reaction takes place at temperatures between 140 and 240°C and requiring for final purification a further step of dissolution in alcohol. The product obtained in both processes has in the majority of the examples a high melt point, reaching 270°C in some cases, which would require high processing temperatures during the step of molding of the polypropylene resins to warrant a good dispersion between the polymer and the nucleating agent. No details are given on the efficiency obtained in removing neutral (unsaponifiable) contaminants from the rosin, nor on the maximum limits to allow the application thereof in nucleation of polyolefins without transfer of odor or flavor. No details are given on the final color of the product obtained.

A disadvantage to the use of nucleating agents derived from rosin is related to the intense color of the raw material that will be transferred to the polypropylene resin to be nucleated. US Patents Nos. 4,643, 847 and 4,657, 703 describe purification methods intended to lightening the color of the rosin and esters thereof. The presence of color may be further aggravated by decomposition reactions, both induced by the high processing temperature of the resin, in the case of nucleating agents having a high melt point, and by incompatibility with other additives present in the final composition of the resin,

particularly under alkaline pH conditions.

The technical literature neither describes nor suggests the subject matter described and claimed in the instant application, since even that which describes a process of partial neutralization of disproportionated rosin does not describe a nucleating agent obtained from the rosin containing impurities having an optimized melt point, in order to ease the dispersion thereof during processing of the resin. The specialized literature also does not describe a process for provision of a nucleating agent which product obtained directly from rosin containing impurities evidences a substantial reduction of the color thereof or of the possibility of generation of color during processing of the resin, allowing the use thereof as a nucleating agent without transfer of color to the polyolefin to be nucleated and clarified and to the products made therefrom. The literature also does not describe a process for providing a nucleating agent from rosin which product has a limited content of undesirable unsaponifiable contaminants in order to avoid the transfer of odor or flavor to the resins and to foodstuffs in contact therewith.

Therefore, the prior art still demands improvements, since the specialized literature does not describe an improved process for production of a nucleating agent from disproportionated rosin, and also does not describe the improved product obtained using the said process and the application thereof to polypropylene and polyethylene resins, intended to accelerate and to improve the resin crystallization process with the consequent improvement of its optical and mechanical properties.

SUMMARY OF THE INVENTION This invention relates to an improved process for production of a

nucleating and clarifying agent from disproportionated rosin and the application thereof to polypropylene and polyethylene resins.

The improved process for production of a nucleating agent from disproportionated rosin, according to the present invention, comprises the following steps: a) dissolution of the disproportionated rosin in an oxygenated organic solvent, preferably ethanol under heat; b) neutralization with caustic potash; c) cooling of the solution at low temperatures in order to precipitate a crystal containing mostly hydroabietic acid and its potassium salt, and in lesser amount, other resinous acids and potassium salts thereof; d) filtration of the suspension removing the impurities that remain soluble in the solvent; e) rinsing, using the same solvent used in the dissolution of the disproportionated rosin, the cake obtained in (d) in order to keep the content of impurities within limits that do not jeopardize the quality of the product; f) drying the rinsed cake; and g) recovering of the residues.

Optionally, the material obtained in step (e) may be subjected to a second crystallization cycle, with redissolution thereof in the same solvent under heat and repeating steps (c), (d) and (e), in order to perfect the removal of impurities.

Thus, the present invention provides an improved process for production of modified rosin from disproportionated rosin, using crystallization

by cooling to purify the product, obtaining thereby the desired product with a high yield.

The present invention further provides an improved process for production of modified rosin from disproportionated rosin, whereby it is possible to control the melt point of the product obtained between 190 and 219°C, preferably between 196 and 215°C, thereby evidencing better dispersion in polypropylene and polyethylene resins during processing thereof in the molding of the resin for its final application.

The present invention further provides an improved process for production of modified rosin from disproportionated rosin, whereby the control of the alkalinity of the product obtained allows the application thereof as an additive for polypropylene and polyethylene resins without inducing degradation reactions of other additives present in the final composition of the resin.

The present invention also provides an improved process for production of modified rosin from disproportionated rosin, whereby the product obtained has an extremely low color and an extremely low content of unsaponifiable compounds such as alcohols, aldehydes and esters, allowing the use thereof as a nucleating agent in polypropylene and polyethylene resins without transfer of undesirable characteristics, as the yellowing of the said resins or the incidence of odor or flavor on the products in contact therewith.

The present invention also provides an improved process for application of this modified rosin in polypropylene and polyethylene resins using low processing temperatures, below 220°C, allowing to reduce the

consumption of energy in the transformation of the resin.

The present invention further provides an improved process for application of this modified rosin in polypropylene and polyethylene resins using low processing temperatures, below 220°C, whereby the resin evidences less degradation, with a consequent decrease of its yellowing rate.

The present invention further provides an improved process for the production of modified rosin from disproportionated rosin, whereby the residue of the rosin is recovered and subsequently used.

BRIEF DESCRIPTION OF THE DRAWING The attached FIGURE 1 depicts in the form of a block diagram, a simplified flow chart of the improved process for production of a nucleating agent from disproportionated rosin and the alternative method thereof, as described and claimed in the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In general, the present invention comprises an improved process for the production of a nucleating agent from disproportionated rosin and the application thereof to polypropylene resins.

Throughout the instant specification, the terms below have the following meaning: -Disproportionated rosin: the rosin-based resin preferably extracted from pine trees of the species Pinus that was subjected to a

disproportionation reaction by dehydrogenation, transforming most of the abietic acid present therein in de-hydroabietic acid and containing other resinous acids in addition to small quantities of unsaponifiable substances.

- Modified rosin: the disproportionated rosin with partial neutralization of its total acidity according to the process described in the present invention.

-Melt flow rate: the result of the test conducted in accordance with standard ASTM D-1238, consisting in measuring the extrusion time of a sample of melted polymer through a capillary conduit and a matrix of determined length and diameter, under stable temperature and pressure conditions. The melt flow rate is expressed in g/10 min.

- Gardner Color : the method used to determine the color of yellowish or maroon materials. This method is applied for the rosin and related products according to standards ASTM D 6166 and D 1544.

The thermoplastic resins, such as the polyethylene resins and particularly the polyethylene resins intended for the markets of films, blow- molding, thermoforming and injection molding, use an increasing amount of nucleating and clarifying agents for purposes of enhancement of fast formation of the crystals, optimizing the transformation process and improving the optical and mechanical properties of the molded product.

The rosin-based resin extracted from pine trees of the species

Pinus contains mostly resinous acids, particularly abietic acid, neoabietic acid, palustric acid, dehydroabietic acid, pimaric acid, isopimaric acid and sandaracopimaric acid. In addition to these acids the rosin-based resin contains small amounts of unsaponifiable substances such as alcohols, aldehydes and esters.

One form of rosin commonly available in the market is disproportionated rosin, which at that stage is not yet adequate to be used as a nucleating agent. It must be purified and neutralized with a certain proportion of an alkali, in order to optimize its effectiveness, transforming it in a modified rosin that is highly effective as a nucleating agent.

The disproportionated rosin results in a mixture containing mostly resinous acids. In general, it is composed mostly (45 to 90% by weight) of dehydroabietic acid, of a lesser proportion (10 to 40% by weight) of other resinous acids such as dihydroabietic acid, abietic acid, neoabietic acid, palustric acid, sandaracopimaric acid, isopimaric acid and pimaric acid and a small amount (less than 12% by weight) of unsaponifiable impurities such as alcohols, aldehydes and esters. Its color, depending on the degree of purification that it undergoes, varies between pale yellow and dark maroon, and its Gardner color grading is usually above 4.

The improved process described and claimed in the present invention is used for the preparation of the modified rosin from the disproportionated rosin. In addition to allowing to obtain a product with an extremely high nucleating power, this process provides other advantages such as

the reduction of coloring of the product obtained to very light color grades, the adequation of the amount of undesirable impurities and of the alkalinity of the final product to levels that do not jeopardize its quality and the application thereof to thermoplastic resins and the possibility of controlling the melting point of the product obtained within optimized values for use as a nucleating agent for nucleating and clarifying polypropylene and polyethylene resins.

The improved process according to the present invention comprises the following steps: a) Complete dissolution of the disproportionated rosin in an organic solvent oxygenated under heat. Preferably, ethanol is used as solvent in an amount of 1 or 2 liters of alcohol per kg of disproportionated rosin, more specifically in an amount of 1.5 to 1.7 liter of alcohol per kg of disproportionated rosin, in a reactor under stirring with the medium heated at a temperature between 60 and 80°C. b) Neutralization of the acidity of the solution prepared in step (a) by adding thereto caustic potash (KOH). The quantity of caustic potash is between 0.02 and 0.08 kg of KOH per kg of rosin. The reaction should be kept at a temperature between 60 and 80°C. The duration of this step may vary from a few minutes to several hours, depending on factors such as the temperature of the medium and the amount of caustic potash used. In general this step takes between 30 minutes and 2 hours. c) Cooling of the solution obtained in step (b) to a temperature between 0 and 20° C, in order to precipitate a solid containing mostly dehydroabietic acid and its potassium salt, in addition to small amounts of other

resinous acids and potassium salts thereof. The amount of other resinous acids present together with their potassium salts is between 1 and 40% by weight, depending on the composition of the original disproportionated rosin and the conditions of the process. The time required to conduct this step may vary between 20 minutes and 24 hours. d) Filtration of the suspension obtained in step (C), in order to remove the impurities that remain soluble in the solvent. The temperature of this step should be kept between 0 and 20°C. e) Rinsing of the cake of crystallized material obtained in step (d), preferably using the same type of solvent used for dissolving the disproportionated rosin in step (a), at a temperature below 15°C. Optionally, the crystallized material obtained in step (e) may be subjected to a second crystallization cycle, by re-dissolution thereof with about 1 to 2 liters of the same solvent used in step (a) per kg of rosin, at a temperature between 60 and 80°C. The solution is once again cooled, filtered and rinsed in the same conditions of steps (c), (d) and (e). f) Drying of the crystal obtained in step (e) in order to eliminate all residual solvent. This operation takes place at a temperature between 50 and 100°C. The drying time should be sufficient to remove the solvent used until that the quantity thereof in the product is below 0.2%. This time is related to the type of solvent used and the drying conditions and is on average between 2 hours and 12 hours. This step may be advantageously conducted in an inert atmosphere such as in nitrogen or under vacuum or combining these two

conditions. g) Recovery by evaporation of the residue contained in the filtrate and in the mother liquor. This residue is comprised by the solvent used, by resinous acids that remained soluble and by unsaponifiable residue of the original rosin. It may be used for other applications or even redirected to the present process.

The process described and claimed by the present invention may use any type of equipment among that which is normally employed in the individual operations of the steps described herein. There may be advantageously used multipurpose equipment able to conduct steps from (a) to (f) with Nutsche-type filters/reactors.

In the case of using ethanol as solvent in steps (a) and (e) of the process described and claimed by the present invention, the same should have a low water content, between 0 and 5.0 kg of water per 100 kg of ethanol.

Preferably, the ethanol used should contain between 0 and 1.0 kg of water per 100 kg of ethanol.

The caustic potash used may be in the form of scales, lenticles, flakes, crystals or any other solid form in which it is marketed. Alternatively, the caustic potash used may be fed in pre-solubilized form or in suspension in the very solvent used in the process. The concentration of the caustic potash is not critical to the process. Preferably, it should contain a minimum of 70% by weight of KOH and a maximum of 30% by weight of water. Additionally, up to

50% of the KOH used may be substituted by NaOH or by Mg (OH) 2 containing at most 30% by weight of water.

In one of the modalities of the present invention the addition of alkali in the dissolution step is monitored and controlled by measuring the pH of the solution. Preferably, values of pH above 9.0 during step (b) should be avoided. In this manner it is possible to avoid that the medium reaches strongly alkaline ranges of pH, warranting the end product to have low alkalinity.

The conduction of the steps of crystallization (c), filtration (d) and rinsing (e) at low temperatures is a fundamental factor both for the high yield of the process and for the quality of the product obtained since in these conditions there are minimized possible degradation reactions of its components with the consequent formation of coloring.

Even if the unsaponifiable substances present in commercial rosin, such as alcohols, aldehydes and esters, are not crystallizable, the same remain adsorbed and eventually occluded in the formed crystals. Some of these substances may contribute to the presence of color in the resin to be nucleated and to the transfer of odor and flavor to products that come into contact with this resin. Therefore, even if there is a filtration step, the amount of these substances that would remain in the final product would render the obtained product inadequate to be used. The rinsing step, and in cases of raw materials with a high content of these components, the optional step of redissolution, that integrate the process according to the present invention, are critical steps for obtaining products with low content of these undesired impurities.

The product obtained after drying may eventually be dispersed mechanically or even ground to adjust the grain size of the particles.

The product obtained in step (f) is a modified rosin having clarification and nucleating agent characteristics, with an extremely low Gardner color value, high purity due to the extremely low content of unsaponifiable impurities, such as alcohols, aldehydes and esters, controlled alkalinity and optimized melting point dependent on the processing temperature usually employed in polypropylene transformation processes. Its melting point is between 190 and 219°C, preferably between 196 and 215°C, which is possible to achieve by the composition of the final product and the degree of neutralization thereof.

The product obtained by means of the process according to the present invention, optimized for use as a nucleating agent, consists predominantly in dehydroabietic acid and its potassium salt (60 to 98% by weight) and a lesser proportion (1 to 40%) of other resinous acids, particularly dihydroabietic acid, abietic acid, neoabietic acid, palustric acid, sandaracopimaric acid, isopimaric acid and pimaric acid and potassium salts thereof. The content of unsaponifiable impurities, among which alcohols, aldehydes and esters, is extremely low, and is between 0 and 1.2% by weight, and allows the application thereof in polyolefinic resins without restrictions.

When the process includes the optional step of redissolution of the cake obtained, the content of unsaponifiable impurities is even lower, standing between 0 and 0.5% by weight. The degree of neutralization should vary between 10 and 60%, preferably between 15 and 45% of the total of free acids.

Even in the cases where the degree of neutralization is lower than 25%, there are maintained the high yield of the process and the great capacity of nucleation and clarification of the product obtained.

Some additives commonly employed in polyethylene and polypropylene resins, especially phenolic antioxidants, exhibit degradation reactions and formation of color in alkaline pH, restricting the use of other additives with alkaline characteristics in the final composition of the resin. Preferably, pH values in excess of 8 should be avoided in the medium comprised by the resin and its additives. The modified rosin produced using the process according to the present invention is comprised by a mixture of weak organic acids, partially neutralized by a strong alkali. In consequence, its alkalinity shall be dependent on the acids that integrate the composition thereof, and above all, on the degree of neutralization thereof. The process described and claimed by the present invention allows the provision of a nucleating agent from disproportionated rosin with controlled alkalinity. Preferably the pH value of an ethanol solution at 1 % by weight, of the product obtained at the end of the process according to the present invention should be equal to or higher than 9.0, and most preferably this pH value should be equal to or lower than 8. 5.

The Gardner color value of commercial disproportionated rosin used as raw material is generally equal to or higher than 4. The great color reduction obtained by employing the process according to the present invention allows the use of commercial disproportionated rosin as raw material without the need of any prior treatment. The Gardner color value of the modified rosin thus obtained is between 0 and 1.

Generally, the product obtained using the process according to the present invention should be added to the polypropylene or the polyethylene to be nucleated at a ratio between 1, 000 ppm and 7,000 ppm. The easy dispersion of the product, due to having an optimized melting point, allows the same to be mixed during the granulation of the polymer or even directly feeding the transformation equipment. Materials that are appropriate to be nucleated using the product according to the present invention include polypropylene homopolymers and polypropylene copolymers using other a-olefins as comonomers, such as ethylene, butene or pentene and which melt flow rate is between 0.4 and 300 g/10 min. Similarly, the low-density linear polyethylenes using as comonomers propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl 1- pentene and 1-octene, with melt flow rate between 0.4 and 10 g/10 min and density between 912 and 930 Kg/m3 are favorably nucleated using the product of the present invention. The polypropylenes and the polyethylenes thus nucleated may be competitively employed in a wide variety of transformation processes such as blow molding, thermal molding, film extrusion and injection molding to be used in the most varied applications.

Due to the nucleating agent described and claimed by the present invention having a low melting point, the application thereof in processes of transformation of polypropylene and polyethylene may be advantageously conducted at processing temperatures below 250°C, preferably below 220°C, reducing both the risks of degradation of the resin and the consumption of energy during the transformation process.

EXAMPLES

The present invention shall now be illustrated by the following examples, which should not be deemed limitative thereto.

Examples 1 to 22 In a 5-liter glass reactor, jacketed and with stirring means, there were added 900 g of disproportionated rosin with the following composition: - Acidity rate = 172.86 mg KOH/g of rosin Dehydroabietic acid content = 58.2%, by weight Sandaracopimaric acid content = 4.0%, by weight Isopimaric acid content = 6.3%, by weight Dihydroabietic acid content = 14.6%, by weight - Abietic acid content = 0.1 %, by weight Content of other resinous acids = 11. 8%, by weight -Content of unsaponifiable materials = 5.0%, by weight The Gardner color of the disproportionated rosin used had a value of 4.

Thereafter, there were added various amounts of KOH (Table 1) with 90%, by weight, of purity and 10%, by weight, of water and 1800 ml of ethanol with various water contents by weight (table 1). In examples 9 and 10, there was used as alkali NaOH with 98%, by weight, of purity.

The mixture was heated until 78° C for total dissolution of the components and was kept at that temperature while stirring for 30 minutes (neutralization phase). Subsequently, the temperature was lowered as per Table 1 (TC) and maintained for 3 hours until full crystallization had taken place (lSt

crystallization). The suspension was filtered in a filter under vacuum and rinsed with a certain amount of alcohol (Table 1). In examples 1 to 7 and in example 10, the cake obtained was dried in a stove under vacuum at 80°C for 12h. In examples 8 and 9 the cake obtained was subjected to recrystallization and was suspended while stirring, redissolved at 78°C for 30 minutes in ethanol, with the same content of the first dissolution, at a ratio of 2 kg of ethanol for kg of solid matter. This ratio also includes the ethanol present in the cake containing the solid to be crystallized. The solution was cooled at 12°C and maintained for 3 hours until full crystallization had taken place (2nd crystallization). The suspension formed was filtered and rinsed under vacuum and finally dried in the same conditions of the lSt srystallization.

The main conditions of the process as well as the properties of the nucleating agent obtained thereby are shown in Table 1. The yields shown refer to the amount of product obtained relatively to the quantity of disproportionated rosin used. Each nucleating agent formed was subjected to a differential scanning calorimetric analysis (DSC) in an inert medium for assessment of enthalpy and melting temperature. In order to obtain the melting temperature (Tml), 5-10 mg of sample material was heated at a rate of 10°C/min in the temperature range from 20 to 300°C. The melting temperature was taken at the peak of the endothermal melting curve in the stipulated temperature range.

The performance of the nucleating agent obtained in examples 1 to 10 was tested. The agents obtained were granulated with a polypropylene at a concentration of 5,000 ppm, together with 500 ppm of calcium stearate and 1200

ppm of the antioxidant blend composed of a phosphite-based secondary antioxidant and a phenolic-based primary antioxidant at a ratio of 2: 1. The base resin for the test was a copolymer of propylene and ethylene with 3.5% by mass of ethylene and a melt flow rate of 1.8 g/10 min (example 11).

Table 2 depicts the main properties of the nucleated polypropylenes. For purposes of comparison there is shown as reference the data of the base resin without nucleating agent and of a sample of that same resin with a typical content of 2,000 ppm of a sorbitol-based nucleating agent (Millad 3988), both with the same additivation of calcium stearate and antioxidants of examples 1 to 10 (example 12).

The crystallization temperatures were measured by DSC in each resin. Each additivated resin was subjected to a differential scanning calorimetric analysis (DSC) in inert medium for assessment of enthalpy and crystallization temperature (Tc). In order to obtain the crystallization temperature, a sample of between 5 and 10 mg was heated at a rate of 10°C/min in the temperature range of 20 to 250°C and maintained at that temperature for 5 minutes. Subsequently the sample was cooled from 250°C to 20°C at a rate of 10°C. The crystallization temperature was taken at the peak of the exothermal crystallization curve in the stipulated temperature range.

There were also measured the opacity and the clarity of each additivated resin under standardized conditions. The opacity is defined as the percentage of transmitted light that on passing through the sample deviates from the incident beam by scattering thereof at an angle in excess of 2. 5°. Clarity is

the percentage of transmitted light that on passing through the sample deviates from the incident beam by scattering thereof at an angle lesser than 2. 5°. The measurements of opacity and clarity were taken using an opacimeter operating in the conditions described in standard ASTM D-618 in test bodies prepared according with standards ASTM D-1003 and ASTM D-4101.

There were additionally measured the flexural modulus of the nucleated resins and of the base resin in a universal mechanical testing machine according to the method of standard ASTM D-790.

Table 1 pst Rising C stallization Rinsing Neutra-HZO in Nucleating TC rY _ alcohol Yield Tml Agent (°C) KOH NaOH (i) 2 crysta !- (% p/p) (°C) lization (I) 1 1 7 73. 5-4-42. 5 0. 05 30. 0 22 7 73. 5-442. 5 4. 00 17. 2- 3 3 7 32. 7-4-18. 9 0. 05 42. 2 204 4 4 7 73. 5-4-42. 5 0. 70 32. 7 198 5 5 7 49. 1-4-28. 4 0. 70 43. 3 199 6 6 12 32. 7-4-18. 9 0. 70 45. 6 206 7 7 12 32. 7-4-18. 9 0. 30 48. 3 207 8 8 12 43. 2-1 1 25. 0 1. 00 48. 9 208 9 9 12 43. 2 20. 6 1 1 41. 7 1. 00 27. 8 200 10 10 12-30. 9 2-25. 0 5. 00 23. 0 174

where: TC is the cooling temperature of the crystallization step of the process.

Tml: is the melting temperature of the modified rosin used as nucleating agent.

The Gardner color value of all the nucleating agents obtained in examples 3 to 9 was below 1.

The content of unsaponifiable impurities of the nucleating agent obtained in example 7 was 0.8% by weight, and in example 8 was 0.4% by weight.

Table 2 Example Nucleating TcPP (°C) Opacity (%) Flexural Modulus Agent pua 11 Base Resin 100 77. 8-- 12 Millad 118 32. 8 85. 7 958 2, 000 ppm 13 1 14 2---- 15 3 119 24. 0 86. 1- 16 4 119 20. 1 85. 4- 17 5 119 19. 8 84. 8- 18 6 121 22. 3 86. 0 19 7 121 19. 1 86. 4 978 20 8 120 21. 2 86. 6 1013 21 9 119 19. 4 87. 0 1058 22 10 118 46. 5 82. 6 1098

where: TcPP : is the crystallization temperature of the nucleated polypropylene Example 23 This example aims to reproduce the synthesis of a nucleating

agent from the same raw material of the previous examples, but following the conditions of example 13 of US patent No. 5, 998, 576. In a 200 ml glass reactor, jacketed and with stirring means, there was added 10 g of disproportionated rosin having the following composition: - Acidity rate = 172.86 mg KOH/g of rosin - Dehydroabietic acid content = 58. 2%, by weight - Sandaracopimaric acid content = 4.0%, by weight - Isopimaric acid content = 6.3%, by weight - Dihydroabietic acid content = 14.6%, by weight Abietic acid content = 0. 1%, by weight - Content of other resinous acids = 11. 8%, by weight -Content of unsaponifiable materials = 5.0%, by weight Thereafter there was added KOH with 90%, by weight, of purity and 10% by weight, of water, in sufficient quantity for 50% neutralization of the rosin used. There was introduced 50 ml of ethanol with 1% by weight, of water.

The mixture was then heated to 40°C and kept at this temperature for 30 minutes with full dissolution of the components (neutralization step). Thereafter, under atmospheric pressure, the alcohol was evaporated from the solution at a temperature of 78°C until there was provided a solution with 60-70%, by weight, of the modified rosin. Subsequently the temperature was lowered to 60°C and maintained for 24 hours until the total separation of the formed crystals. The precipitate was filtered, rinsed with alcohol and dried in a vacuum stove at 80°C (nucleating agent 11).

The yield of the nucleating agent thus obtained was very low, corresponding to only 11.0% of the initial rosin. The nucleating agent obtained also evidenced characteristics that were different from those of the product of the present invention, since it did not evidence a crystalline melting temperature (Tml not defined). Both the yield and the characteristic of the product obtained indicate that the process described by the US patent No. 5,998, 576 is not adequate to produce nucleating agents from certain types of rosin with low content of dehydroabietic acid.

Therefore, the illustrative examples of the present invention evidence a comparative advantage not only regarding the base resin but also relatively to the prior art, both due to the greater yield of the process and to the characteristics of the product obtained.

There may also be noted the advantage residing in the optical properties of the polymers nucleated with the nucleating agents prepared with KOH or the nucleating agent prepared with the mixture of KOH and NaOH compared to the nucleating agent of example 10 that is merely prepared with NaOH. There may also be noted the superior performance of the formulations including modified rosin as compared to the standard formulation including a sorbitol derivative.

Example 24 In a 304 stainless steel reactor with a capacity of 20 liters, provided with jacket and stirring means, there was added 13.0 kg of disproportionated rosin, 20.54 kg of ethanol with 0.5% water content and 0.624

kg of KOH with 90% purity. The mixture was heated to 78°C and was kept at that temperature while stirring for 30 minutes. After that time had elapsed, the mixture ceased to be stirred and the temperature was lowered to 12°C and maintained for 10 hours until complete crystallization was achieved (Ist crystallization). After the crystallization, the cake formed was subjected to vigorous stirring for 30 minutes and subsequently there was performed a filtration, using a horizontal plate filter under pressure of nitrogen and without stirring. To the cake thus obtained there was added 11.4 kg of iced (12°C) rinsing ethanol, which was mixed while stirring. Subsequently, without stirring, there was performed a filtration under pressure of nitrogen (1 St rinse). Thereafter, 16. 8 kg of ethanol was added to the mixture and the temperature was raised to 78°C and maintained for 30 minutes while stirring to achieve full solubilization.

Immediately after, without stirring, the temperature was lowered to 12°C (2nd crystallization) and maintained for 3 hours. After the recrystallization, the stirring means was reactivated again to suspend the cake, and upon switching off the stirring means, the content of the reactor was filtered under pressure of nitrogen. To the remaining mass there was added 8.2 kg of iced (12°C) rinsing ethanol which was mixed with the cake under vigorous stirring. With the stirring means turned off, there was performed a filtration (2nid rinse). Subsequently, the remaining mass was dried by flow of nitrogen at a temperature between 80 and 90°C for 1.5 hours (nucleating agent 12).

The results relative to example 24, with the data relative to the condition of synthesis, yield, melting temperature of the formed product, crystallization temperature of the additivated polymer and transparency and clarity achieved with nucleating agent 12 are shown in Table 3.

TABLE 3 Neutralization Yield (%) Tml TcPP Opacity (%) Clarity (%) (%) (°C) (°C) 25 52.0 206 120 19.3 86. 5

The nucleating agent of example 24 was further subjected to an infrared spectroscopy reading using a Nicolet Nexus 470 spectrophotometer to determine the characteristic absorption bands of the obtained product. The characteristic absorption wave numbers of the obtained product were (in cm~l) : 2925, 1710, 1550, 1500, 1470, 1380,1345, 1275, 1245, 1180, 1135, 1040, 950, 905, 880, 820, 715 Of these, absorption wave numbers 1350, 1140, 1040,950, 900, 880 and 710 cri 1 were not reported in the products of the examples cited in US patent No. 5, 998, 576. Other absorption wave numbers (2925, 1710, 1470, 1385, and 1245 cm~l) are slightly offset regarding those reported by that patent. The absorption wave number 950 cm~l, in connection with which US patent No.

5,998, 576 affirms that it does not appear in any of its infrared-characterized examples, appears very clearly in the spectrum of the product of example 24 of the present invention.

Therefore, the reasoning and examples of the present specification evidence the distinctive points of the present invention vis-a-vis the prior art, rendering the process according to the invention not suggested and not obvious regarding the literature published on the subject.

These distinctive points are: (i) Use of an improved process for production of modified rosin, from disproportionated rosin, using crystallization by cooling below 15°C to purify the product, obtaining thereby a high yield of the desired product when starting from a rosin with low content of dehydroabietic acid.

(ii) Optimized modified rosin having a controlled melting point in the range between 196 and 215°C, evidencing thereby a better dispersion performance in polypropylene and polyethylene resins.

(iii) Modified rosin optimized due to its extremely low color and its low rate of unsaponifiable compounds, such as alcohols, aldehydes and esters, even starting from an impure rosin with an intense color, advantageously allowing the use thereof as a nucleating agent in polypropylene resins without transfer of undesirable characteristics, such as yellowing of the polypropylene resin or the incidence of odor or flavor in products in contact therewith.

(iv) Optimized modified rosin with controlled alkalinity such as to allow the use thereof as additive in polypropylene and polyethylene resins without inducing degradation reactions of other additives present in the final composition of the resin.

(v) An improved process for application of this modified rosin in polypropylene and polyethylene resins using low processing temperatures, below 220°C, allowing to reduce the energy consumption in the transformation

process.

(vi) An improved process for application of this modified rosin in polypropylene and polyethylene resins using low processing temperatures, below 220°C, allowing to reduce the risks of degradation of the polymer.

(vii) An improved process for production of modified rosin, from disproportionated rosin, wherein the residue is recovered and subsequently used.