JP5666236B2 - Lubricating composition - Google Patents

Description

  The present invention relates to a lubricating composition comprising a base oil, in particular a Fischer-Tropsch derived base oil.

  For example, as described in 2nd Asia-Pacific base oil Conference, Beijing, China, 23-25 October 2007. J. et al. Wedlock et al. , “Gas-to-Liquids Base Oils to Assistance in Meeting OEM requirements 2010 and beyond”, Fischer-Tropsch derived groups in lubricating compositions such as engine oils, transmission fluids, and industrial lubricating oils. By using oil, various performance advantages are obtained. Examples of performance benefits from using the Fischer-Tropsch derived base oil described in the above documents include improved oxidation characteristics, improved engine cleanliness, improved wear protection, improved exhaust, and Improved post-processing device compatibility. Fischer-Tropsch base oil can also be used to formulate energy-saving formulations with low viscosity.

  It has also been found that Fischer-Tropsch derived base oil can be used as a carrier oil for additive concentrates. As an example, WO2009 / 074572 discloses the combined use of a Fischer-Tropsch derived base oil and an alkylated aromatic component such as an alkylated naphthalene used as a carrier oil for a viscosity modifier. Applicants have used SAE 0W-30, 0W-40, 5W-30, and 5W-40 engine oils containing olefin copolymers (OCP) while using Fischer-Tropsch derived base oil as the carrier oil for OCP. It has also been found that it can be blended.

International Publication No. 2009/074572

D. presented in 2nd Asia-Pacific base oil Conference, Beijing, China, 23-25 October 2007. J. et al. Wedlock et al. , “Gas-to-Liquids Base Oils to Assistance in Meeting OEM requirements 2010 and beyond”

  One object of the present invention is to improve the antioxidant properties of lubricating compositions.

  Another object of the present invention is to provide an alternative lubricating composition.

One or more of the above or other objects is a lubricating composition of the present invention, i.e.,
A base oil selected from the group consisting of a Fischer-Tropsch derived base oil and a poly-alpha olefin (PAO) base oil, or combinations thereof;
A detergent,
It is realizable by the lubricating composition containing an amine compound.

  Surprisingly, it has been found that the lubricating composition according to the invention exhibits improved antioxidant properties.

  There is no particular limitation on the base oil used in the lubricating composition according to the present invention, and various conventional ones can be used provided that at least a Fischer-Tropsch derived base oil or poly-alpha olefin (PAO) base oil is present. Naturally derived esters such as mineral oils, synthetic oils and vegetable oils can be conveniently used.

  The base oil used in the present invention may advantageously comprise a mixture of one or more mineral oils and / or one or more synthetic oils, and according to the present invention, therefore, the term “base oil” It can mean a mixture containing more than one type of base oil. Mineral oils include liquid petroleum, as well as paraffinic, naphthenic, or mixed paraffin / naphthenic solvent-treated or acid-treated mineral lubricating oils, which can be hydrofinished and / or dewaxed. Can be further purified.

  Suitable base oils for use in the lubricating oil compositions of the present invention include Group I, Group II, Group III mineral base oils, Group IV poly-alpha olefins (PAO), Group III Fischer-Tropsch derived base oils. , And mixtures thereof.

  “Group I”, “Group II”, “Group III”, and “Group IV” base oils in the present invention are in the definition of American Petroleum Institute (API) classifications I, II, III, and IV. Means a compliant lubricant base oil. These API classifications are defined in API Publication 1509, 15th Edition, Appendix E, April 2002.

  Fischer-Tropsch derived base oils are well known in the art. The term “Fischer-Tropsch derivation” means that the base oil is or is derived from a synthetic product of the Fischer-Tropsch process. Fischer-Tropsch derived base oils are sometimes referred to as GTL (Gas-To-Liquid) base oils. Suitable Fischer-Tropsch derived base oils that can be conveniently used as base oils in the lubricating compositions of the present invention are, for example, EP 0769959, EP 0668342, WO 97/21788, WO 00/15736, WO 00/14188, WO 00/14187, Base oils disclosed in WO00 / 14183, WO00 / 14179, WO00 / 08115, WO99 / 41332, EP1029029, WO01 / 18156, and WO01 / 57166.

  Synthetic oils include hydrocarbon oils such as olefin oligomers (including poly-α-olefin base oils, ie PAO), dibasic acid esters, polyol esters, polyalkylene glycol (PAG) s, alkylnaphthalenes, and depolymerized oils. There may be mentioned waxy isomerates. Synthetic hydrocarbon base oils sold under the name “Shell XHVI” (trademark) by Shell Group may be conveniently used.

Poly-alpha olefin base oils (PAO) and their manufacture are well known in the art. Preferred poly -α-olefin base oils that may be used in the lubricating composition of the present invention, straight-chain _C 2 _{-C 32,} preferably may be derived from _C 6 _{-C 16} alpha-olefins. Particularly preferred raw materials for the poly-α-olefins are 1-octene, 1-decene, 1-dodecene, and 1-tetradecene.

  According to the present invention, the base oil used in the lubricating composition of the present invention is at least one selected from the group consisting of a poly-alpha olefin base oil, a Fischer-Tropsch derived base oil, or combinations thereof. Contains base oil.

  Considering the high production cost of PAO, it is highly preferred to use a Fischer-Tropsch derived base oil rather than a PAO base oil. Thus, preferably the base oil is greater than 50% by weight, preferably greater than 60% by weight, more preferably greater than 70% by weight, even more preferably greater than 80% by weight, most preferably greater than 90% by weight. Contains Fischer-Tropsch derived base oil. In a particularly preferred embodiment, no more than 5%, preferably no more than 2% by weight of the base oil is not a Fischer-Tropsch derived base oil. Even more preferably, 100% by weight of the base oil is based on one or more Fischer-Tropsch derived base oils. Preferably, the base oil or base oil mixture comprising a Fischer-Tropsch derived base oil has a kinematic viscosity (according to ASTM D 445) at 100 ° C. between 2 and 30 cSt, preferably between 2.5 and 10 cSt.

  The total amount of base oil contained in the lubricating composition of the present invention is preferably in the range of 60 to 99% by weight, more preferably in the range of 65 to 90% by weight, based on the total weight of the lubricating composition. In an amount in the range of 70 to 85% by weight.

  There is no particular limitation on the detergent used in the lubricating composition according to the present invention, and various conventional detergents may be used. Examples of detergents that can be used are sulfonates, phenates, oil-soluble, neutral and overbased metals, especially alkali metals or alkaline earth metals, such as sodium, potassium, lithium, especially calcium and magnesium. , Sulfurized phenates, thiophosphonates, salicylates, and naphthenates, and other oil-soluble carboxylates. Preferred metal detergents are neutral and overbased detergents having a TBN of 20 to 450 mg KOH / g (Total Base Number according to ASTM D2896). According to one preferred embodiment, the detergent has a TBN value in the range of 60 to 240, preferably less than 240 mg KOH / g, such as less than 200 mg KOH / g. Combinations of detergents that are either overbased or neutral, or both, may be used.

  Typically, the detergent, or detergent mixture, is in an amount of 0.01 to 5.0% by weight, based on the total weight of the lubricating oil composition fully formulated in the lubricating composition according to the present invention. Exists.

  According to a preferred embodiment of the present invention, the detergent is a salicylate detergent. Examples of suitable salicylate detergents are the trade names “Infineum C9012”, “Infinium M7101”, “Infinium M7102”, “Infinium M7105”, “Infinium M7121” and “Infinium” from Infineum. Products available under "M7125".

  There is no particular limitation on the amine compound used in the lubricating composition according to the present invention, and various conventional amine compounds may be used. Examples of suitable amine compounds include monoamines, diamines, and polyamines.

  According to a preferred embodiment of the present invention, the amine compound is an aromatic amine compound. Examples of suitable aromatic amine compounds include diphenylamines, alkylated diphenylamines, phenyl-α-naphthylamines (PANA), phenyl-β-naphthylamines, and alkylated α-naphthylamines. Preferably the aromatic amine is selected from optionally alkylated diphenylamine and optionally alkylated phenyl-α-naphthylamine, more preferably selected from optionally alkylated diphenylamine.

  The above (optionally alkylated) diphenylamine (DPA) compounds are well known in the art and are widely commercially available. Examples of suitable diphenylamines and phenyl-α-naphthylamines that can be used include diphenylamine (DPA), butyldiphenylamine, dibutyldiphenylamine, octyldiphenylamine, dioctyldiphenylamine, nonyldiphenylamine, dinonyldiphenylamine, heptyldiphenylamine, diheptyldiphenylamine, Methyl styryl diphenylamine, mixed butyl / octylalkylated diphenylamines, mixed butyl / styrylalkylated diphenylamines, mixed nonyl / ethylalkylated diphenylamines, mixed octyl / styrylalkylated diphenylamines, mixed ethyl / methylstyrylalkylated diphenylamines, Phenyl-α-naphthylamine, octylphenyl-β-naphthoni Naphthylamine, t-octylphenyl-α-naphthylamine, phenyl-β-naphthylamine, p-octylphenyl-α-naphthylamine, 4-octylphenyl-1-octyl-β-naphthylamine, n-t-dodecylphenyl-1 Examples include, but are not limited to, -naphthylamine, N-hexylphenyl-2-naphthylamine, and mixed alkylated phenyl-α-naphthylamines. Commercially available examples of diphenylamines and phenyl-naphthylamines are trade names Irganox L-06 and Irganox L-57 from CIBA Specialty Chemicals, and trade names Naugarube AMS, 38 , Naugarvae 438L, Naugarove 640, Naugarove 680, Naugarove APAN, and Naugard PANA; T. T. et al. Available from Vanderbilt Company, Inc. under the trade name Vanlube DND, Van Roube NA, Van Roube PNA, Van Roube SL, Van Roube SLHP, Van Roube SS, Van Roube 81, Van Roube 848, and Van Roube 849, and also available from Albemarle under the trade name AN-1225 is there.

  Typically, the amine compound is 0.1 to 10.0% by weight, preferably 0.1 to 5.0% by weight, more preferably based on the total weight of the fully formulated lubricating oil composition. It is present in an amount in the range of 0.2 to 4.0% by weight, most preferably 0.3 to 1.5% by weight.

  According to one particularly preferred embodiment of the invention, the aromatic amine compound has the general formula (I)

（式中、各Ｒは独立して、１から１６個の炭素原子、好ましくは３から１４個の炭素原子、より好ましくは４から１２個の炭素原子を有するアルキル基である。）
を有するジフェニルアミンである。

Wherein each R is independently an alkyl group having 1 to 16 carbon atoms, preferably 3 to 14 carbon atoms, more preferably 4 to 12 carbon atoms.
It is a diphenylamine having

  Lubricating compositions according to the present invention comprise antioxidants, antiwear additives, dispersants, detergents, overbased detergents, extreme pressure additives, friction modifiers, viscosity index improvers, pour point depressants, metal One or more additives may further be included such as a mobilizing agent, a corrosion inhibitor, a demulsifier, an antifoaming agent, a seal compatibility agent, and a base oil that dilutes the additive.

  Those skilled in the art are familiar with these and other additives and will not be discussed further herein. Specific examples of such additives are described in, for example, Kirk-Othmer Encyclopedia of Chemical Technology, third edition, volume 14, pages 477-526. The above mentioned additives are typically present in an amount in the range of 0.01 to 35.0% by weight, based on the total weight of the lubricating composition, preferably based on the total weight of the lubricating composition. Present in an amount in the range of 0.05 to 25.0% by weight, more preferably in the range of 1.0 to 20.0% by weight.

  The lubricating composition of the present invention can be conveniently prepared by mixing one or more additives with a base oil.

  The lubricating composition according to the invention is preferably a so-called “low SAPS” (SAPS = sulphated ash, phosphorus and sulfur), “mid SAPS”, or “regular SAPS” formulation.

In the case of Passenger Car Motor Oil (PCMO) engine oil, the above range is
Up to 0.5 wt%, up to 0.8 wt%, and up to 1.5 wt% of sulfated ash, respectively (according to ASTM D 874),
Up to 0.05 wt%, up to 0.08 wt%, and typically up to 0.1 wt% phosphorus, respectively (according to ASTM D 5185), and up to 0.2 wt%, up to 0.3 wt%, respectively % By weight, and typically up to 0.5% by weight of sulfur (according to ASTM D 5185)
Means.

In the case of heavy duty diesel engine oil (Heavy Duty Diesel Engine Oil), the SAPS range is
1% by weight, 1% by weight and 2% by weight, respectively, of sulfated ash (according to ASTM D 874),
Up to 0.08% (low SAPS) and up to 0.12% (intermediate SAPS) phosphorus content (according to ASTM D 5185), respectively, and up to 0.3% (low SAPS) and up to 0.4 respectively Weight% (intermediate SAPS) sulfur content (according to ASTM D 5185)
Means.

  The lubricating composition of the present invention can be adapted to the above SAPS range of engine oils even when the lubricating composition is intended for different applications.

  Further, the lubricating composition of the present invention may be adapted to a specific industrial standard such as SAE J300 standard (revised in January 2009). Preferably, the lubricating composition according to the present invention complies with SAE J300 0W-20, 5W-30, 5W-40, and 10W-40 crankcase engine oil specifications, preferably 10W-40. SAE stands for Society of Automotive Engineers.

The composition is
Absolute viscosity at −25 ° C. of less than 7000 cP (according to ASTM D 5293),
Kinematic viscosity at 100 ° C. (according to ASTM D 445) of at least 12.5 cSt and typically less than 16.3 cSt,
High temperature high shear viscosity of at least 3.5 cP (according to “HTHS”, ASTM D 4683), and less than 14 wt%, preferably less than 13.0 wt%, more preferably less than 11.0 wt%, even more preferably Particularly preferred according to the invention is a Noack volatility (according to ASTM D 5800) of less than 10.5% by weight, most preferably less than 10.0% by weight.

  The lubricating composition according to the present invention can be used in various applications such as transmission oil, grease, hydraulic oil, turbine oil, compressor oil, etc. in an internal combustion engine (as engine oil).

  In another aspect, the present invention is to improve antioxidant properties, particularly as determined by HPDSC according to ASTM D 6186-08 and / or by ROBO testing according to ASTM D 7528-09. Of the lubricating compositions described herein are provided.

  The invention will now be described with reference to the following examples, which are in no way intended to limit the scope of the invention.

Examples Lubricating oil compositions Various combinations of additives and base oils were formulated. Table 1 shows the properties of the base oil used. Table 2 shows the amount of additive contained in each base oil, and the amount of additive (the balance is base oil) is based on the total weight of additive and base oil. It is shown in units of weight percent. For ease of reference, Table 2 also includes a reference to “Mixtures 1 to 21” containing a combination of two or more additives and a base oil.

“Base oil 1” (or “BO1” or “GTL 4”) was a Fischer-Tropsch derived base oil with a kinematic viscosity at 100 ° C. (ASTM D445) of about 3.9 cSt (mm ² s ⁻¹ ). . Base oil 1 (and base oil 3 described below) can be conveniently prepared, for example, by the methods described in PCT Publication WO 02/070631, the teachings of which are incorporated herein by reference.

  “Base oil 2” (or “BO 2”) was a commercially available Group III base oil with a kinematic viscosity at 100 ° C. (ASTM D445) of about 4.3 cSt. Base oil 2 is commercially available, for example, from SK Energy (Ulsan, Korea) under the trade name “Yubase 4”.

“Base oil 3” (or “BO3” or “GTL 8”) was a Fischer-Tropsch derived base oil with a kinematic viscosity at 100 ° C. (ASTM D445) of about 7.7 cSt (mm ² s ⁻¹ ). .

  “Base oil 4” (or “BO 4”) was a commercially available Group III base oil having a kinematic viscosity at 100 ° C. (ASTM D445) of about 6.5 cSt. The base oil 4 is commercially available from SK Energy under the trade name “Ubase 6”, for example.

  The following additives A1 to A22 were used.

  A1: Octylated / butylated diphenylamine (DPA) available under the trade name “Irganox L-57” from CIBA Specialty Chemicals (Basel, Switzerland).

  A2: R.A. T. T. et al. Dioctylated diphenylamine available from Vanderbilt (Norwalk, Connecticut, USA) under the trade designation "Banlube 81".

  A3: 4,4'-bis (α, α, -dimethylbenzyl) diphenylamine available from Chemtura (Middlebury, Connecticut, USA) under the trade name “Naugalube AMS”.

  A4: Octylated phenyl-α-naphthylamine (PANA) available from CIBA Specialty Chemicals under the trade name “Irganox L-06”.

  A5: Liquid high MW phenolic antioxidant available from CIBA Specialty Chemicals under the trade name “Irganox L-135”.

  A6: R.A. T. T. et al. An oligomeric amine compound in a synthetic ester available from Vanderbilt under the trade name “Ban Louve 9317”.

  A7: a dinuclear molybdenum-sulfur compound available from Infineum International Ltd (Abington, UK) under the trade name “Infinium C9455”.

  A8: Molybdenum dithiocarbamate available from Adeka under the trade name “Sakura-Lube 515”.

  A9: R.A. T. T. et al. Ashless dithiocarbamate available from Vanderbilt under the trade name “Ban Roube 7723”.

  A10: Thiodipropionic acid ester available from CIBA Specialty Chemicals under the trade name “Irganox PS800 FL”.

  A11: R.A. T. T. et al. 2-Ethyl-hexyl-dithiophosphate available from Vanderbilt under the trade name “Banlube 727”.

  A12: A thiophosphate amine available under the trade designation “Lz 5125” from Lubrizol Corporation (Wickliffe, Ohio, USA).

  A13: primary zinc dithiophosphate (ZDTP) available from Lubrizol Corporation under the trade name “Lz 1395”.

  A14: Second grade ZDTP available from Lubrizol Corporation under the trade name “Lz 1371”.

  A15: Mixed ZDTP available from Infineum International Ltd. under the trade name “Infinium C9417”.

  A16: Low BI (basicity index) salicylate detergent (Ca-based) available from Infineum International Ltd. under the trade name “Infinium M7102”. Properties: Vk40 (270); Vk100 (19); TBNE (total base number equivalent (ASTM D 2896); mgKOH / g) = 64; Ca (wt%) = 2.3.

  A17: Infineum International Ltd. More intermediate BI salicylate detergent (Ca-based) available under the trade name “Infinium M7121”. Properties: Vk40 (1130); Vk100 (95); TBNE (mg KOH / g) = 225; Ca (wt%) = 8.0%; Mg (wt%) = 0.24.

  A18: High BI salicylate detergent (Ca-based) available from Infineum International Ltd. under the trade name “Infinium M7125”. Properties: Vk40 (835); Vk100 (100); TBNE (mg KOH / g) = 350; Ca (wt%) = 12.5; Mg (wt%) = 0.3.

  A19: Reaction product of an acidic organic compound, a boron compound, and a basic organic compound available from Chemtura. See, for example, US2005 / 0172543 and in particular this paragraph [0025] to [0077].

  A20: Sulfonate detergent available from Infineum International Ltd. under the trade name “Infinium C9350”. Properties: Vk40 (2300); Vk100 (130); TBN (mg KOH / g) = 16.5; Ca (wt%) = 2.15.

  A21: A phenate detergent available from Infineum International Ltd. under the trade name “Infinium C9394”. Properties: TBN (mg KOH / g) = 258; Ca (wt%) = 9.5.

  A22: Mg-based salicylate detergent available from Infineum International Ltd. under the trade name “Infinium C9012”. Properties: Vk 100 (65); TBNE (mg KOH / g) = 345; Mg (wt%) = 7.45.

HPDSC Oxidation Stability Test High pressure differential scanning calorimetry (HPDSC) is used to show the antioxidant properties of the lubricating composition according to the present invention, according to ASTM D 6186-08, at 200 ° C. Oxidation induction time (OIT) measurements were made while exposed to 200 psig oxygen (instead of the prescribed 500 psig) at a temperature of An aluminum sample pan was used. The oxidation induction time can be used as an index of oxidation stability.

SAE 10W-40 Formulations In addition, various low SAPS SAE 10W-40 (PCMO) engine oils were formulated for use in passenger car crankcase engines.

  Table 3 shows the composition and properties of the fully formulated engine oil formulations that were tested. The component amounts are given in units of weight percent based on the total weight of the fully formulated formulation.

  All engine oil formulations tested contained a combination of base oil, additive package, detergent, and amine, and the additive package was the same for all compositions tested.

  The additive package is a so-called low SAPS (low sulfated ash, phosphorus, and sulfur) PCMO formulation, i.e., up to 0.5 wt% sulfated ash, up to 0.05 wt% phosphorus, and up to 0.2 It had a weight percent sulfur content. The additive package contained a combination of additives including antioxidants, zinc-based antiwear additives, ashless dispersants, pour point depressants, about 3 ppm antifoam agent, and conventional viscosity modifier concentrates.

  The compositions of Examples 1 to 3 and Comparative Examples 1 to 3 were obtained by mixing the base oil with the additive package using conventional lubricant mixing procedures.

ROBO Oxidation Test A ROBO (Romaszewski Oil Bench Oxidation) test according to ASTM D 7528-09 was used to demonstrate the aging properties of lubricating compositions according to the present invention. Was measured. This bench test method obtains characteristics equivalent to the oil degradation properties obtained with ASTM TMC Sequence IIGA matrix standard oils 434, 435, and 438 after degradation in the Sequence IIG engine test. Is intended.

  The measured viscosity increase, apparent viscosity, and yield stress are shown in Table 4 below.

DISCUSSION As can be seen from Table 2, in particular the improvement of the antioxidant properties (increased HPDSC response) of mixtures 14, 15, and 19 (containing a combination of amine and detergent in a Fischer-Tropsch derived base oil) Based on the performance of individual components, it was higher than expected. As an example, mixture 14 (containing 0.5% by weight of amine A1 and 3.5% by weight of detergent A16 in Fischer-Tropsch derived base oil 1) showed an OIT of 109.5 minutes (from mineral origin). Compared to 68.2 minutes for Group III base oil). This is surprisingly higher than the sum of the contributions of 0.5% by weight of amine A1 in BO1 (8.0 minutes) and 3.0% by weight of detergent A16 in BO1 (15.1 minutes). . Thus, in particular, the performance of mixtures 14, 15, and 19 in Fischer-Tropsch derived base oils is synergistic when compared to the sum of the individual OIT contributions. From mixtures 14, 15, and 19, the performance of the same amine and the same detergent in the same amount in the Fischer-Tropsch derived base oil is equivalent to the performance of the same component in the mineral-derived group III base oil. It can also be seen that it is significantly better (long OIT) than. This clearly shows a synergistic effect.

  Furthermore, when comparing mixtures 14 and 15 with mixtures 16 and 21, the actual OIT values of mixtures 14 and 15 are much higher, so that they have a low or intermediate BI, ie, 240 mg KOH / g, such as in the range of 60 to 240 mg KOH / g. It can be seen that detergents having a TBN of less than g are preferred for the present invention over high BI detergents.

  Furthermore (see Table 4) the compositions of Examples 1 to 3 (containing Fischer-Tropsch derived base oil) according to the present invention have a (desirable) decrease in viscosity increase and compositions according to Comparative Examples 1 to 3 (minerals). It was found to show a lower end-of-test (EOT) viscosity than the base oil of origin). Furthermore, the yield stress is significantly reduced in the composition according to the present invention as compared with the comparative example. This further illustrates the synergistic behavior of the combination of detergent, amine compound, and Fischer-Tropsch derived base oil claimed by the present invention, as also shown in Table 2.

Claims (6)

A base oil that is a Fischer-Tropsch derived base oil or a mixture of more than 90% by weight of a Fischer-Tropsch derived base oil and a poly-alpha olefin (PAO) base oil;
A detergent,
Only contains an amine compound,
The amount of the base oil ranges from 70 to 85% by weight, based on the total weight;
Having up to 0.5 wt% sulfate ash, up to 0.05 wt% phosphorus, and up to 0.2 wt% sulfur,
The detergent is a salicylate-type detergent having a TBN value in the range of less than 240 mg KOH / g, the amount of the detergent being in the range of 0.01 to 5.0% by weight, based on the total weight;
The amine compound has the general formula (I)

Wherein each R is independently an alkyl group having 1 to 16 carbon atoms. The amount of the amine compound is 0.1 to 5. based on the total weight. It is in the range of 0% by weight
A lubricating composition characterized by the above . The lubricating composition of claim 1 , wherein the detergent has a TBN value in the range of 60 to 240 mg KOH / g. Each R is independently of the amine compound, Ru alkyl der having 14 carbon atom from 3 A lubricating composition according to claim 1 or 2. The lubricating composition according to claim 3, wherein each R of the amine compound is independently an alkyl group having 4 to 12 carbon atoms. To improve antioxidant properties, use of the lubricating composition according to any one of claims 1 4. 6. Use according to claim 5 for improving the antioxidant properties as measured by HPDSSC according to ASTM D 6186-08 and / or ROBO test according to ASTM D 7528-09.