TECHNICAL FIELD

The present invention relates to lubricant compositions comprising glycerol mono-ester for being used particularly in PVC applications and a method for production of said compositions.

KNOWN STATE OF THE ART

Glycerol mono-oleate is an ester structure used in plastic sector, particularly in PVC applications as lubricant. Lubricants reduce the friction between polymer-polymer, metal- metal, polymer-metal, filler-filler and polymer-filler. Said lubricants have high compliancy and low evaporation characteristics.

Like all polymers, PVC comprises long-chained molecules. These are substantially viscose in melt form and are inclined to adhere to the metal components of processing equipment. By using lubricants, this problem can be overcome. The basic function of the lubricants in rigid PVC (rPVC) and in other polymers is to reduce inner and outer friction. Thus, advantages like easiness in flow at lower temperatures, decrease in the dissolving inclination of the polymer, increase in the production proportion, decrease in the abrasion of equipment and lower energy consumption are obtained.

Lubricants are generally classified as inner or outer lubricants. The dissolvability of the lubricant is in general determined by the molecular structure of the polymer and the polarity thereof. Because of the fragmenting risk of the polymer between the lubricant and the polymer, a complete dissolvability is not desired. In the two types, even if the lubricant is mixed with the PVC polymer, it shows different functions. However, most of the lubricants have combinations with both outer and inner sliding characteristics.

Outer lubricants do not dissolve substantially in PVC. They are migrated onto the polymer surface in melt form and they show outer sliding property on the metal surface of the process equipment. In this case, the bonding force between the polymer and the lubricant is weak. The lubricant substance covers the metal surface of the processing equipment and decreases the friction of the surface and provides outer sliding. Inner lubricants mostly dissolve in PVC. During the process, they operate in a molecularly included manner to the movement of PVC chains and they function as inner lubricant. The desired effect for an inner lubricant is to provide that the polymer chains shall arrange themselves in a manner providing guiding towards the flow direction. Thus, the sliding tension between the polymer molecules is decreased by the inner lubricant, and thus, the melt viscosity and temperature increases are reduced.

Since operating commercial-scale equipment has substantially high-cost, in the beginning, their effects of a new developed lubricant system on the rPVC compound are measured by using laboratory-scale equipment like rheometers, dynamic two-rollered mills, small-scale moulding machines and extruders.

Whether a material is an inner lubricant or an outer lubricant depends on the joinability of the material with rPVC, the adhesion durations and the effects on melt viscosity. The inner lubricants do not substantially affect the adhesion durations, however, they decrease melt viscosity. The outer lubricants affect the adhesion durations; however, they do not substantially decrease the melt viscosity. These characteristics can be measured by a torque rheometer and in dynamic two cylinder mill. rPVC can be processed in various equipment like extruders (both single and double screwed), calendering machines and injection molding machines.

The lubricant system shall be balanced in terms of the processing and final usage characteristic requirements. While the single-screw extruders need inner and outer lubricant balance, the double-screw extruders, calenders and injection moulders need more outer lubricants. The lubricant systems are not only balanced for the processing equipment, and at the same time, the lubricants affect the required final usage characteristics in a favorable manner. A formulation which is completely optimized provides high output amount, low waste proportions, high quality finished products and the required physical characteristics. Insufficient or excessive amount of lubricant leads to decrease of the processing efficiency or even stop processing. A balanced lubricant system (with the correct amounts of both the inner and the outer lubricants) provides control on the thermal stability durations, output proportion, blooming, transparency and physical characteristics.

Although there are lubricant classes at a substantially wide range for rPVC, most of them are considered as wax or soap. The five main chemical classes are as follows: amides, hydro carbon waxes, oil acid esters, oil acids and metallic soaps. There are pluralities of types of ester lubricants used in various rPVC formulations: simple esters, glycerol esters, poly-glycerol esters, montan esters, partial esters of the multi functional alcohols, completely esterified esters of multi-functional alcohols. These esters are made of various alcohols and oil acids except montan esters. These lubricants are generally named as oil acid esters. Esters are generally versatile and their characteristics can change as inner or outer lubricant as a result of increasing carbon chain length and esterification degree. Therefore, the sliding characteristics of an ester can be adapted for specific applications.

The mono-esters of high saturated oil acids are colorless, odorless and crystallized solids. These are among the esters which have the strongest inner lubricant function. The most frequent glycerol is mono-stearate (GMS). GMS has some“outer” characteristics and it is mostly an “inner” lubricant. The increase of the esterification degree increases the outer sliding characteristic. Moreover, since GMS has low toxicity, it can also be used as food additive substance.

The most frequent oil acid used as a lubricant for rPVC is the mixture of palmitic (chain length with 16 carbons) and stearic (chain length with 18 carbons) acids. Besides some inner lubricant characteristics, these are one each good outer lubricants at the same time. The greatest disadvantages are that their volatilities are low.

Glycerol esters (glycerides) are obtained as a result of reacting of glycerol and oil acids by means of esterification. As a result of this reaction, water occurs and moreover, mono-, di- and triglyceride mixtures occur. Mono-glycerides shall be separated by means of molecular distillation under high vacuum. The basic disadvantage of said chemical method is that the product efficiency is low and molecular distillation cost is high.

In the known state of the art, chemicals like para-toluene-sulphonic acid, sulphuric acid, zinc oxide, zinc chloride, aluminum chloride are used in production of mono-glyceride. In addition to gylcerol and oil acid components which are biodegradable, methods where the catalyst is herbal and biodegradable are needed.

In the application with number US 2010/01481 17, a method is disclosed where mono glyceride production is realized without using catalyst. The glycerol-oleic acid proportion used in said method is 2.2:1 . Thus, the glycerol put in excessive amount shall be removed from the medium at the end of the reaction. This leads to excessive cost and time loss. Moreover, in said method, the reaction temperature is between 250°C and 255°C and this is a substantially high temperature. Moreover, pressure usage leads to extra cost.

Moreover, in the products obtained by means of catalysts used in the known state of the art, there is generally color problem.

As a result, because of all of the abovementioned problems and because of the insufficiency of the present solutions about the subject, an improvement is required in the related technical field.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a suitable lubricant composition for plastic, particularly for PVC applications and a method for production of said composition, for meeting the above mentioned requirements and for eliminating the above mentioned disadvantages and for bringing new advantages to the related technical field.

The main object of the present invention is to provide a lubricant composition production method with high product efficiency.

Another object of the present invention is to provide a simple lubricant composition production method with low cost.

Another object of the present invention is to provide a lubricant composition production method realized by means of biodegradable and environment-friendly materials.

Another object of the present invention is to provide a lubricant composition production method realized at low temperatures.

Another object of the present invention is to provide a lubricant composition production method which eliminates the color problem of the obtained product.

Another object of the present invention is to provide a biodegradable and environment- friendly catalyst.

Another object of the present invention is to provide a lubricant composition with increased performance. Another object of the present invention is to provide a PVC product with increased product quality.

In order to realize all of the abovementioned objects, the subject matter method for producing a lubricant composition comprising glycerol mono-ester, comprises reacting of a mixture, which comprises glycerol and an oil acid, in the presence of catalyst as olive leaf extract including oleuropein.

In order to realize the objects of the present invention, the method for producing a lubricant composition comprising glycerol mono-oleate comprises reacting of a mixture, comprising glycerol and oleic acid, in the presence of catalyst as olive leaf extract comprising oleuropein between 120°C and 200°C until the acid value is 3.0 or lower and until the glycerol mono- oleate percent is at least 90%.

In order to realize the objects of the present invention, the catalyst, for producing a lubricant composition through the reaction by means of esterification of glycerol and oil acids, comprises olive leaf extract comprising oleuropein.

In order to realize the objects of the present invention, the lubricant composition comprises olive leaf extract comprising oleuropein.

In order to realize the objects of the present invention, the PVC product comprises olive leaf extract comprising oleuropein.

The structural and characteristic properties and all advantages of the present invention will be understood in a more clear manner by means of the below mentioned detailed description and evaluation shall be made by taking into consideration the below mentioned detailed description.

DETAILED DESCRIPTION OF THE INVENTION

In this detailed description, the preferred embodiments of the subject matter composition and the production method of said composition are explained with references to examples without forming any restrictive effect only in order to make the subject more understandable.

The present invention describes compositions comprising glycerol mono-ester for use as additive substance and/or lubricant in plastic, particularly in PVC applications, and a new method for producing these. In the production method of the subject matter lubricant composition, olive leaf extract is used as catalyst during esterification of glycerol and oil acids.

In the present application,“glycerine” and“glycerol” are used interchangeably.

In the present application, “glycerol ester” and “glyceride” are used interchangeably and these mean a molecule having at least one oil acid part bonded to the main chain of glycerol by means of ester bond. Mono-glycerides or mono-glycerol esters comprise one oil acid part and diglycerides comprise two oil acid parts and triglycerides comprise three oil acid parts.

In the present application,“oil acid” means an acyl chain bonded in a covalent manner to a carboxyl functional group. The oil acid can be in“free form” where the carboxyl group does not make another covalent bond or“glyceride form” (mono-, di- and/or tri-glyceride) bonded to the glycerol.

In the present application,“percent” means mass percent.

In the present application, the term lubricant is used. Lubricant means the additive substance which reduces the friction between polymer-polymer, metal-metal, polymer-metal, filling-filling or polymer-filling. Here, “filling” means filling substance which can be calcium carbonate, carbon fiber, magnesium silicate hydroxide, carbon black, silica, caoline, etc. Filling substances are materials which provide the product with low cost and which provide toughness.

The oil acids used in the present invention can be obtained from any oil acid source. Oil acids can be substituted or unsubstituted, saturated or unsaturated and can have between 10 and 22 carbon atoms. The preferred oil acids can be for instance decanoic acid, lauric acid, miristic acid, palmitic acid, penta-decanoic acid, stearic acid, arachidic acid, behenic acid, margaric acid, miristoleic acid, palmitoleic acid, oleic acid, gadoleic acid, erucic acid, risinoleic acid, linoleic acid, lisanic acid, margaroleic acid, arachidonic acid, clupanadonic acid, eicosa-pentaeonic acid, docosa-hexaenoic acid, oil acids obtained from soya bean, oil acids obtained from coconut, oil acids obtained from palm oil, oil acids obtained from palm seed and oil acids obtained from tallow.

In a preferred embodiment of the present invention, the oil acid source comprises oleic acid or stearic acid. In a more preferred embodiment of the present invention, the oil acid source comprises oleic acid.

In the present invention, olive leaf extract, prepared from olive leaf, is used as catalyst. Olive leaf extract has been adapted to have a wide specific surface area for synthesizing mono glyceride from glycerol and oil acid by means of esterification. Thus, by means of the present invention, biodegradable catalyst is used instead of an inorganic catalyst, and herbal solution is obtained.

In the known state of the art, inorganic catalysts like para-toluene sulphoic acid, sulphuric acid, zinc oxide, zinc chloride, aluminum chloride are used in production of mono-glyceride, particularly mono-oleate. In the subject matter method, olive leaf extract is used instead of these types of catalysts.

Olive foliage comprises pluralities of anti-oxidant character poly-phenols, primarily oleuropein. Thanks to these, the oxygen in the glycerol can attack more to the carbonyl carbon in the oil acids. In other words, said phenols provide the carbonyl carbons to react in an easier manner.

The subject matter method is a method for producing a composition comprising glycerol mono-ester; said method comprises reacting of the mixture, comprising glycerol and an oil acid, in the presence of olive leaf extract comprising oleuropein and without another catalyst.

Since the olive leaf extract used in the subject matter method is a bio-sourced material, the obtained product is completely environment-friendly and biodegradable. The glycerol mono ester product, obtained by means of this, can be used as plastic additive and moreover can be used in food products and food package products like stretch film.

The general structure of glycerol mono-esters is shown by the general Formula (I) below.

Formula (I) In the present art, mono-glycerides are produced commercially by means of glycerolysis of oils. In said processes, oil acids and glycerol are reacted by means of esterification and results in water and mono-, di- and triglyceride mixtures. Afterwards, mono-glycerides shall be separated by means of molecular distillation under high vacuum. The basic disadvantage of said chemical method is that the product efficiency is low and molecular distillation cost is high.

When the esterification reaction is realized by using olive leaf extract, the mono-glyceride selectivity and the obtained mono-glyceride percent increase substantially. Since the mono glyceride percent is high, the inner lubricant characteristic of the product is greater. Moreover, the olive leaf extract can be prepared by means of simple methods with high efficiency.

Glycerol mono-oleate, whose chemical structure is shown by formula (II) below and also named as mono-oleol-glycerol, glyceril 1 -oleate, glyceril-mono-oleate or 1 -mono-olein, is a synthetic mono ester. It is classified as a member of 1 -mono-acyl-glycerol family. The mono- acyl-glycerols comprising a glycerol which is acylated in 1 -position are named as 1 -mono- acyl-gylcerols. Glycerol mono-oleate has water-insoluble and relatively neutral structure.

Formula (II)

Glycerol is obtained by reacting mono-oleate glycerin and oleic acid in the presence of a catalyst to obtain mono-glyceride ester (mono-glyceride). Normally, one mole of oleic acid is used for one mole of glycerol; however, at the end of the reaction, a mixture is obtained. As a result of this reaction, a composition, which comprises mono-ester, diester and triester, is formed in the medium. When the subject matter olive leaf extract is used as catalyst, approximately 90% proportion mono-ester (in other words, glycerol mono-oleate) is formed through this reaction selectively.

The reaction monitoring has been realized by measuring acid value at specific periods. The reduction in the acid value shows whether there is acid in the medium or not and gives information about the transformation of oleic acid in the reaction medium. Reduction of the acid value may take long time. In relation to this, the catalyst amount in the reaction is changed and the temperature is changed and the reactor stirring speed is changed and the acid value reaches the desired levels.

In the present application, “acid number” means the mass of potassium hydroxide as miligrams which is needed to neutralize one gram of chemical susbtance. Acid value measures the amount of carboxylic acid groups in the chemical solution. In the present application, the acid number gives the measure of the free oil acid in the solution.

In esterification reactions, generally high temperature intervals are used particularly in the synthesis of long-chain oil acids. Higher temperatures lead to blackening of the colors of oil acids and dissolving of the oil acids.

In a preferred embodiment of the present invention, the reaction is realized between 120°C and 200°C.

In a further preferred embodiment of the present invention, the reaction is realized between 150°C and 170°C.

The used oil acids can be solid or liquid, and the reaction medium is stirred in a homogeneous manner and the stirrer speed shall be at a specific level in order to prevent accummulation of the solid inputs at the bottom of the reactor.

In a preferred embodiment of the present invention, the reaction is realized at reactor stirring speed between 50 and 500 rpm.

In a further preferred embodiment of the present invention, the reaction is realized at 140 rpm.

Oleuropein exists more than 140 mg/g in the dry substance of oils and reaches 60-90 mg/g concentration in the dry substance of foliage (Morello et.al, 2005; Omar, 2010). In a preferred embodiment of the present invention, the amount of catalyst on the base of the total weight of the inputs (glycerol and oil acid) in the reaction is between 0.05-20%.

In a further preferred embodiment of the present invention, the amount of catalyst on the base of the total weight of the inputs in the reaction is 0.3%.

The reaction duration changes according to the type of the used oil acid, the catalyst amount, the used vacuum amount.

In a preferred embodiment of the present invention, the reaction is realized between 2 and 24 hours.

The proportions of glycerol and oil acid used in order to provide desired characteristics to said composition bear importance. In the studies to obtain mono-ester, generally the glycerokoil acid molar proportion is 1 :1 . On the other hand, glycerol can be used in a greater amount in order to execute the realized reaction product through more mono-esters in a selective manner. However, this leads to an additional cost for removing the extra glycerol at the end of the reaction. Thus, high glycerol amounts have not been used in the present invention.

In a preferred embodiment of the present invention, the molar proportion of glycerokoil acid is between 1 :1 and 5:1 .

Since the reactions are realized at high temperatures and since a part of the used glycerol will diverge from the medium during the reaction, it is preferred that the glycerokoil acid proportion is greater than 1 .

In a further preferred embodiment of the present invention, the molar proportion of glycerokoil acid is 1 .1 :1 .

The vacuum used for removing the whole water which occurs at the end of the reaction realized in the subject matter method is generally a value which is close to full vaccum. In other words, it is approximately -0.7 bars.

Since the colors of oil acids begin to blacken at high temperatures, the reaction is realized under nitrogen gas. During the reaction, water occurs as the side product. In order to remove the water, vacuum is applied to the mixture. The reaction is continued according to the acid amount in the medium. When there is no acid in the medium, the reaction is ended. After the mixture is cooled, the mixture is filtered and the product is taken for removing the solid catalyst in the medium. The excessive catalyst, which remains without dissolving, is removed from the medium thanks to this. Thus, a part of the catalsyt, even if it is little in amount, remains inside the product.

In the present invention, when glycerol and oleic acid are reacted in the presence of olive leaf in the synthesis, the acid value reduces from 190 mg KOH/g to the levels lower than 3 mg KOH/g. Moreover, the glycerol mono-oleate percent increases by 10-20% in an unexpected manner according to the condition where metal catalyst is used. Thus, glycerol mono-oleate can be obtained at levels of 90%. Therefore, in the realized extrusion applications, it has been found that a synergic increase occurs in the sliding effect of the subject matter lubricant composition. In the subject matter method, olive leaf extract is used as the catalyst. Oleuropein (OE), whose chemical structure is shown in formula (III) below, exists in the olive foliage.

Oleuropein consists of glucosidic esters of hydroxy-tirozol and elenolic acid. Oleuropein (OE), which is a poly-phenol, is the main component of Olea europea which is known as olive tree. Oleuropein also exists in the fruits, shells and roots of the olive tree. Moreover, it can also be obtained from other plant types which belong to the Oleaceae family, for instance from ash tree. However, oleuropein proportion in olive leaf is substantially high. Oleuropein has useful effects on health like anti-atherogenic, anti-aterogenic, anti-viral, anti inflammatory, anti-microbial effects. Moreover, oleuropein prevents lipo-protein oxidation, it is anti-oxidant, and it prevents cancer, and helps prevention of Alzheimer’s disease. The olive leaf extract can comprise oleuropein between 10 mg and 1000 mg.

In olive foliage, moreover, there are other poly-phenols. Among these, for instance, there are apigenine, apigenine-7glucoside, apigenine-7-rutinoside, cafeic acid, 5-caffeoylquinic acid, cinamic acid, o-cumaric acid, p-cumaric acid, cyanidine-3-glucoside, cyanidine-3-rutinoside, demethyl-oleuropein, 3,4-DHPEA-EDA, elenoic acid, elenoic acid glucoside, ferulic acid, gallic acid, hesperidine, homo-orientine, homovanilic acid, 4-hydroxy-benzoic acid, hydroxy- tirazole, ligstroside, luteoline, luteoline-4-glucoside, luteoline-7-glucoside, luteoline-7- rutinoside, nushenide, oleosid, oleuropein aglycone, oleurosid, proto-catechic acid, quersetin, quersitrin, rutin, salidroside, sinapic acid, siringic acid, tirosole, vanilic acid, verbascoside.

In a further preferred embodiment of the present invention, the olive leaf extract comprises a phenolic compound selected from the group consisting of apigenine, apigenine-7glucoside, apigenine-7-rutinoside, cafeic acid, 5-caffeoylquinic acid, cinamic acid, o-cumaric acid, p- cumaric acid, cyanidine-3-glucoside, cyanidine-3-rutinoside, demethyl-oleuropein, 3,4- DHPEA-EDA, elenoic acid, elenoic acid glucoside, ferulic acid, gallic acid, hesperidine, homo-orientine, homovanilic acid, 4-hydroxy-benzoic acid, hydroxy-tirazole, ligstroside, luteoline, luteoline-4-glucoside, luteoline-7-glucoside, luteoline-7-rutinoside, nushenide, oleosid, oleuropein aglycone, oleurosid, proto-catechic acid, quersetin, quersitrin, rutin, salidroside, sinapic acid, siringic acid, tirosole, vanilic acid and verbascoside together with oleuropein.

The subject matter lubricant compositions can be added to plastic, for instance to PVC mixtures at changing proportions.

The subject matter lubricant compositions can be used in polymer shaping processes showing plastic characteristic. Said lubricant compositions are particularly suitable for shaping chlorized polymers like poly-vinil chloride (PVC), poly-vinilidine chloride and the copolymers which are the derivatives thereof.

As an example to the PVC products where the subject matter lubricant compositions are used; window profiles, automobile seat leathers, floor coatings, wallpapers, shoe bases, electrical cables and various packages can be given.

Moreover, the subject matter lubricant compositions can also be advantageously used in shaping all polymers where any lubricant is used in the formulations thereof and used in extrusion and injection studies and which have plastic characteristics like poly-propylene and poly-ethylene.

EXAMPLES

Example 1

Preparation of extract from the olive foliage

Olive foliage are picked from branch one by one and cleaned by washing with water. Afterwards, the dried olive foliage has been extracted by using soxhlet extractor and with the help of an organic solvent like hexane, and all affective substances pass into the solvent. Afterwards, the obtained organic material has been filtered with 0.45 microns filter. Afterwards, the organic phase has been removed by the rotary drier and the solid product is obtained. In experimental studies, this solid material is used as catalyst.

Example 2

Addition of the subject matter catalyst to the reaction The extract material obtained from olive foliage is equal to 0.3% of the total weight of the inputs in the reaction. After glycerol and oleic acid are put to the reactor, the extract is weighed and added. Example 3

Comparison of the mono-ester amount obtained by using the subject matter catalyst with the mono-ester amount obtained by using zinc chloride and p-toluene sulphonic acid