WO2022248131A1 - Composition which can be used as a lubricant - Google Patents

Abstract

The invention relates to a composition comprising a divalent or trivalent alcohol and gelatin and/or gelatin hydrolysate dissolved therein, the composition being liquid at 20 °C.

Description

Composition useful as a lubricant

The present invention relates to a composition which can be used in particular as a lubricant.

The invention also relates to various uses of this composition, in particular as a lubricant.

Lubricants are used in various technical areas, in particular for lubricating moving parts in mechanical devices. Typically, these lubricants are fats and oils that are derived from mineral oil or are synthetically produced. The general disadvantage of such lubricants is the risk of environmental pollution and the need for costly disposal.

To address this problem, various biodegradable lubricants based on vegetable oils have been developed. However, the widespread esters in this product class are particularly sensitive to hydrolysis. In addition, many products are not sufficiently safe for contact with food, despite the plant-based starting point, due to the chemical modification or allergenic effect.

The use of mineral or synthetic lubricants, regardless of whether they are based on mineral oil or vegetable oil, is particularly problematic in technical systems in the food industry, where possible contamination of food must be ruled out, as well as in the forest sector (hydraulic oils) and in the marine sector, where in general, the entry of oils, regardless of their basis, can cause environmental problems. Lubricants or cooling lubricants are also used in manufacturing technology, especially in machining or cold forming of metals or plastics. The release agents or cooling release agents, which are used in particular in casting processes or in the hot forming of metals and plastics, also have a partially comparable function. In all of these applications, residues of the lubricant or release agent pose a problem because on the one hand they require laborious cleaning of the workpieces and on the other hand the residues on the tools (especially in the casting molds) can also impair the further production process.

WO 2011/006777 A1 describes cooling lubricants and cooling release agents for manufacturing technology which are based on an aqueous solution of proteins, in particular gelatin. On the one hand, these agents are biodegradable, on the other hand, they are partially pyrolytically decomposed during the manufacturing process and thus form fewer or more easily removable residues. In addition, the disclosed proteins can be produced in food quality and can also be preserved in a concentrated liquid form with food-grade additives (e.g. citric acid and potassium sorbate).

However, such water-based lubricants have the general disadvantage that they can dry out and are therefore not suitable for continuous use (permanent lubrication).

The present invention is therefore based on the object of proposing a composition which can be used as a lubricant in various areas of application while avoiding the disadvantages mentioned.

According to the invention, this object is achieved by a composition which comprises a dihydric or trihydric alcohol and gelatin and/or gelatin hydrolysates dissolved therein, the composition being liquid at 20.degree. The composition according to the invention therefore ideally contains only substances that are harmless to health and biodegradable as essential components, which are preferably also approved for use in foods. While gelatin has always been used as a food, 1,2-propanediol, also known as propylene glycol, for example, is approved in the European Union as a food additive E1520 (e.g. in chewing gum). 1,2-Propanediol is also used in cosmetics.

In the context of the invention, it was surprisingly found that on the one hand gelatin and especially gelatin hydrolyzate have good solubility in some dihydric or trihydric alcohols, and on the other hand the resulting solutions, which are liquid or viscous at room temperature, have good technical properties for use as a lubricant . In contrast to mineral or synthetic lubricants, the composition according to the invention can also be used without hesitation within suitable limits in the food industry, for example for lubricating moving parts in conveying or filling systems for food. Cleaning and disposal are also generally unproblematic.

According to the invention, dihydric alcohols (diols) or trihydric alcohols (triols) are used as solvents for the gelatin and/or the gelatin hydrolyzate, with dihydric alcohols being preferred. The dihydric alcohol is preferably a glycol, i.e. a 1,2-diol or a 1,3-diol, in particular 1,2-propanediol, ethylene glycol, 1,2-pentanediol or 1,3-propanediol.

The trihydric alcohol is preferably glycerin.

Alternatively, compositions of gelatin and/or gelatin hydrolyzate with higher alcohols, ie polyols, and mixtures of different polyols can also be used. Among other things, sugar alcohols such as erythritol (a tetrahydric alcohol), xylitol (a pentahydric alcohol) or sorbitol (a hexahydric alcohol) can also be used as polyols. These polyols are typically solids which are then used in the form of a syrup, particularly with minimal use of water be able. Another variant is the use of so-called biogenic polyols, which are essentially based on natural products or are themselves natural polyhydroxy compounds.

In addition to lubricating moving parts in mechanical devices, the composition according to the invention can also be used in particular as a lubricant/cooling lubricant or as a release agent/cooling release agent in manufacturing technology, essentially in the same way as the compositions according to WO 2011/006777 A1. In contrast, however, the composition according to the invention has the additional advantage that it does not dry out completely due to the diols or triols it contains, and sticky residues can thus be reduced or even completely avoided.

According to a preferred embodiment of the invention, the composition comprises a proportion of about 45 to about 98% by weight of dihydric or trihydric alcohol and a proportion of about 2 to about 55% by weight of gelatin and/or gelatin hydrolyzate . The proportion of gelatin and/or gelatin hydrolyzate can therefore be varied over a wide range, depending on the field of application of the composition.

The composition according to the invention is liquid at 20° C., which explicitly also includes viscous compositions. In particular, the viscosity of the composition can be influenced from liquid to viscous via the proportion of gelatin and/or gelatin hydrolyzate, which is preferably in the range from approx. 20 mPas to approx. 700,000 mPas, more preferably from approx. 20 up to approx. 280 mPas. For example, a mixture of gelatine hydrolyzate (type B, 3,000 Da average molecular weight) in 1,2-propanediol behaves Newtonically at 60 °C up to a concentration of 10% by weight of gelatine hydrolyzate at a shear rate of 0.1 to 10 s ¹ and a viscosity of 20 mPa·s. For a concentration of 30% by weight of gelatine hydrolyzate, the viscosity is 280 mPas under the same conditions. At a concentration of 50 % by weight of gelatin hydrolyzate, shear thinning properties are observed. The viscosity values are around 700,000 mPa-s at a shear rate of 0.1 s- ¹ and this decreases to 8,000 mPa-s at 10 s- ¹ .

The good solubility of gelatin and gelatin hydrolyzate in dihydric or trihydric alcohols also makes it possible to produce a concentrate with a relatively high proportion of gelatin and/or gelatin hydrolyzate, which is diluted with further solvent before actual use. In a composition according to the invention in the form of such a concentrate, the proportion of gelatin and/or gelatin hydrolyzate is preferably approx.

20 to about 50% by weight.

In a composition according to the invention which is used directly as a lubricant or for another application (that is to say optionally after dilution of a concentrate), the proportion of gelatin and/or gelatin hydrolyzate is preferably about 2 to about 50% by weight.

Advantageously, the composition for use as a lubricant contains no additional water apart from the water bound in the gelatin and/or the gelatin hydrolyzate. The water content of dry gelatin typically ranges from about 8 to 12% by weight. It is therefore preferred if the composition according to the invention has a maximum water content (in the form of the water originating from the gelatin or the gelatin hydrolyzate) of 6% by weight. For applications as a lubricant/cooling lubricant or as a release agent/cooling release agent, on the other hand, the concentrate can be diluted with water to a gelatine hydrolyzate content of approx. 2 to approx. 50% by weight.

The composition according to the invention comprises gelatin and/or gelatin hydrolyzate. Gelatine is created by denaturing and extracting collagen from animal raw materials in a technical process and is characterized by the fact that it forms a solid gel in an aqueous solution at room temperature. In contrast, gelatin hydrolyzate has due to its lower molecular weight does not have the ability to form a gel compared to gelatin. Gelatine hydrolyzate is produced by chemical or enzymatic hydrolysis of gelatine or directly of collagen, the term "gelatine hydrolyzate" in the context of the present invention also explicitly encompassing the latter variant.

In a preferred embodiment of the invention, the composition comprises a gelatin having a bloom value of from about 50 to about 225 g bloom, preferably from about 50 to about 125 g bloom. Low-bloom gelatins have a higher solubility in dihydric or trihydric alcohols (e.g. in 1,2-propanediol), especially if water is also present in the system.

The Bloom value of gelatin correlates to some extent with its molecular weight. The composition of the present invention suitably comprises a gelatin having an average molecular weight of from about 20,000 to about 50,000 Da, preferably from about 20,000 to about 30,000 Da. This information relates to the weight-average molecular weight, which can be determined by means of gel permeation chromatography.

In a further advantageous embodiment of the invention, the composition comprises a gelatin hydrolyzate with an average molecular weight of about 500 to about 25,000 Da, preferably from about 1,000 to about 12,000 Da. This information also relates to the weight-average molecular weight.

Within the scope of the invention, different gelatins, different gelatine hydrolysates or both can be combined with one another in order to vary the properties of the composition according to the invention and to adapt it for specific applications.

The composition according to the invention can also comprise one or more additives in a proportion of up to 5% by weight. Possible additives against microbial contamination are preferably selected from food-grade stabilizers such as potassium sorbate and sodium benzoate, or industrially used stabilizers such as phenoxyethanol, isothiazolinones (eg methylisothiazolinone, chloromethylisothiazolinone and benzisothiazolinone) or ortho-phenylphenol. Formaldehyde releasers, on the other hand, are not suitable because they interact unfavorably with the protein chains. Other additives can be water softeners such as citric acid or triphosphates, as well as anti-corrosion additives such as amines, amine carboxylates, triazine tricarboxylic acids, alkyl-aryl-sulfonamidocarboxylic acids, polycarboxylic acids, amine and sodium-neutralized phosphoric acid esters, as well as surfactants, defoamers, EP additives, AW- Additives, anti-tackiness agents and adhesion promoters.

The present invention also relates to the use of a composition according to the invention as a lubricant, in particular for lubricating moving parts in mechanical devices. Due to the advantages mentioned above, a coordinated composition of the components can also be used as a lubricant in the food industry, especially if no other additives are used.

A further aspect of the invention relates to the use of a composition according to the invention as a lubricant or as a cooling lubricant in manufacturing technology, in particular in machining or in the cold forming of metals or plastics. The advantage here is that protein residues that can form during the machining process as a result of spray mist on machine walls, tool change magazines and clamping plates do not dry up and are therefore easier to remove, as no sticky residue is left behind.

A further aspect of the invention relates to the use of a composition according to the invention as a release agent or as a cooling release agent in production technology, in particular in casting processes or in the hot forming of metals and plastics. Here it is advantageous that the layer remaining on the edge areas of the mold during the spraying process is Proteins does not dry out due to the added solvents and therefore does not leave any sticky residue that can make opening the mold difficult.

Another aspect of the invention relates to the use of a composition according to the invention as a cleaning agent, in particular as an easy-to-clean additive in cleaning agent concentrates and in finished products for surface cleaning (e.g. bathroom, floor, glass and kitchen cleaners), in industrial cleaners ( e.g. for solar cells), as well as in cleaning agent concentrates for motor vehicles and rail vehicles. The advantage here is that the protective layer of proteins that remains after cleaning does not dry out due to the added solvent and therefore does not leave any sticky residue.

In all of the uses according to the invention, it can be provided that the composition is diluted before the actual use by adding further dihydric or trihydric alcohol and/or by adding water. In this case, the composition according to the invention is initially present as a concentrate with a relatively high proportion of gelatin and/or gelatin hydrolyzate. As mentioned above, the addition of water is advantageous, particularly when using relatively high-molecular gelatin, in order to improve its solubility, while gelatin hydrolysates are preferably used for anhydrous compositions.

These and other advantages of the invention are described in more detail with reference to the following exemplary embodiments.

Example 1: Production of lubricants

First, the solubilities of various gelatine hydrolyzates (hereinafter also referred to as collagen peptides) in the solvents 1,2-propanediol, ethylene glycol, glycerol, 1,2-pentanediol and 1,3-propanediol were examined. For this purpose, non-gelling collagen peptides with mean molecular weights of 1 kDa, 2 kDa, 3 kDa, 4 kDa and 10 kDa were used, namely of type A (from acid-processed gelatin) and type B (from alkaline-process gelatin). The solutions were prepared at 60°C, allowed to cool to room temperature and the dissolution behavior evaluated.

The results are summarized in the tables below, and the associated figures in FIGS. 1 to 5 visualize the consistency from liquid to waxy.

In the tables mean:

0 clear solution

(0) clear solution but foaming

0 no clear solution

/ not examined

Beispiel lb: Kollagenpeptide in Ethylenglykol (siehe Fig. 2)

Example la: Collagen peptides in 1,2-propanediol (see Fig.l)

Example lb: collagen peptides in ethylene glycol (see Fig. 2)

Example lc: collagen peptides in glycerol (see Fig. 3)

Beispiel le: Kollagenpeptide in 1,3-Propandiol (siehe Fig. 5)

Example 1d: collagen peptides in 1,2-pentanediol (see Fig. 4)

Example le: collagen peptides in 1,3-propanediol (see Fig. 5)

Example 2: Examination of the smears in the Brugger test

The resilience of the lubricant was determined using the Brugger test (analcg DIN 51347). This is an indirect measurement of the sliding friction of (cooling) lubricants by measuring a friction wear mark on a test cylinder. The surface of the reamed ellipse allows conclusions to be drawn about the effectiveness/function of the (coolant) lubricant used.

Test parameters:

Test specimen: Slip ring, ground in and test cylinder, degreased

Test weight: 1 kg ^ 400 N at the lever arm

Parameters (controlled by the software):

Speed 960 rpm, duration 30 s Measured variables: abrasion surface in mm ² Conditioning: slip ring and test cylinder are degreased with a 2:1 mixture of isopropanol and xylene and then cleaned in acetone. In order to obtain reproducible results, the slip ring must be preconditioned/ground in.

Figure 6 shows a graph of the results of the Brugger test for 10%, 30% and 50% weight fractions of various collagen peptides in 1,2-propanediol.

Figure 7 is a graph showing the results of the Brugger test for 10%, 30% and 50% weight fractions of various collagen peptides in ethylene glycol.

Figure 8 is a graph showing the results of the Brugger test for 10%, 30% and 50% weight fractions of the 1 kDa type A collagen peptide in various solvents.

Figure 9 is a graph showing the results of the Brugger test for 10%, 30% and 50% weight fractions of the 3 kDa type B collagen peptide in various solvents.

Example 3: Examination of the lubricants in the Reichert test

The resilience of the lubricants was also determined using the Reichert test. This is also an indirect measurement of the sliding friction of (cooling) lubricants by measuring a friction wear mark on a test cylinder. The area of the rubbed ellipse allows conclusions to be drawn about the effectiveness/function of the (cooling) lubricant used. In contrast to the Brugger test, however, the slip ring runs in a bath of cooling lubricant. Test parameters:

Capacity: 45 ml

Test specimen: slip ring and test cylinder, degreased

350 N am Hebelarm Test weight: 1 kg + 250 g

350 N at the lever arm

Parameters (controlled by software):

Sliding speed 1.7 m/s, speed 950 rpm,

Running distance 100 m

Measured variables: abrasion surface in mm ² , noise meter

Figure 10 shows a graph of the results of the Reichert test for various 10% by weight collagen peptides in various solvents.

Claims

P atentClaims 1. A composition comprising a dihydric or trihydric alcohol and gelatin and/or gelatin hydrolyzate dissolved therein, the composition being liquid at 20°C. 2. Composition according to claim 1, wherein the composition comprises a dihydric alcohol, which is preferably a glycol, in particular 1,2-propanediol, ethylene glycol, 1,2-pentanediol or 1,3-propanediol. 3. The composition of claim 1 or 2, wherein the composition comprises from about 45 to about 98% by weight of dihydric or trihydric alcohol and from about 2 to about 50% by weight of gelatin and /or gelatin hydrolyzate. 4. The composition of claim 3, wherein the proportion of gelatin and/or gelatin hydrolyzate is about 20 to about 50% by weight. 5. The composition of any one of the preceding claims, wherein the composition has a viscosity of from about 20 mPas to about 700,000 mPas, preferably from about 20 to about 280 mPas. 6. The composition as claimed in any of the preceding claims, where the composition contains no additional water apart from the water bound in the gelatin and/or the gelatin hydrolyzate. 7. The composition of any one of the preceding claims, wherein the composition comprises a gelatin having a bloom value of from about 50 to about 225 g bloom, preferably from about 50 to about 125 g bloom. 8. The composition of any one of the preceding claims, wherein the composition comprises a gelatin having an average molecular weight of from about 20,000 to about 150,000 Da, preferably from about 20,000 to about 30,000 Da. 9. The composition of any one of the preceding claims, wherein the composition comprises a gelatin hydrolyzate having an average molecular weight of from about 500 to about 25,000 Da, preferably from about 1,000 to about 12,000 Da. 10. Composition according to one of the preceding claims, wherein the composition further comprises one or more additives in a proportion of up to 5% by weight, which are preferably selected from stabilizers such as potassium sorbate and sodium benzoate, preservatives such as phenoxyethanol, isothiazolinones (e.g. methylisothiazolinone, chloromethylisothiazolinone and benzisothiazolinone) or ortho-phenylphenol, softeners such as citric acid and triphosphates, anti-corrosion agents such as amines, amine carboxylates, triazine tricarboxylic acids, alkyl aryl sulfonamido carboxylic acids, polycarboxylic acids, amine and sodium neutralized phosphoric acid esters, surfactants, defoamers, EP additives, AW -Additives, anti-tackiness agents and adhesion improvers. 11. Use of a composition according to any one of the preceding claims as a lubricant, in particular for lubricating movable parts in mechanical devices. 12. Use of a composition according to any one of claims 1 to 10 as a lubricant or as a cooling lubricant in manufacturing technology, in particular during machining or cold forming of metals or plastics. 13. Use of a composition according to any one of claims 1 to 10 as a release agent or as a cooling release agent in manufacturing technology, in particular in casting processes or in the hot forming of metals and plastics. 14. Use of a composition according to any one of claims 1 to 10 as a cleaning agent, in particular as an additive in cleaning agent concentrates or in finished products for surface cleaning (e.g. bathroom, floor, glass and kitchen cleaners), in industrial cleaners (e.g. for solar cells), and in cleaning agent concentrates for motor vehicles and rail vehicles. 15. Use according to any one of claims 11 to 14, wherein the composition is diluted before use by adding further dihydric or trihydric alcohol. 16. Use according to any one of claims 11 to 15, wherein the composition is diluted by adding water before use. * * *