Polar-Modified Rice Husk Wax

Abstract

The invention provides polar-modified rice husk waxes obtainable by free-radical grafting of unmodified rice husk waxes with graft comonomers selected from the group of the ,-unsaturated mono- or polybasic carboxylic acids or derivatives thereof. The invention further provides derivatization products prepared by chemical conversion of the polar-modified rice husk waxes of the invention. The invention further provides processes for producing the products of the invention and for the use thereof.

Claims

1. A polar-modified rice husk wax obtained by free-radical grafting of unmodified rice husk wax with one or more graft comonomers selected from the group consisting of ,-unsaturated mono- or polybasic carboxylic acids and derivatives thereof.

2. The polar-modified rice husk wax as claimed in claim 1, having an acid number of 2 to 120 mg KOH/g, a melt viscosity, measured at 90 C., of 20 to 500 mPa.Math.s and a dropping point of 40 to 90 C.

3. The polar-modified rice husk wax as claimed in claim 1, wherein the graft comonomer is maleic anhydride.

4. A process for producing a polar-modified rice husk wax as claimed in claim 1, comprising the step of manufacturing the polar-modified rice husk wax from refined rice husk wax.

5. A derivatization product obtained from a polar-modified rice husk wax as claimed in claim 1, comprising the step of derivatizing the polar-modified rice husk by one or more methods selected from the group consisting of hydrolysis, alcoholysis, esterification, amidation, hydrolysis, ethoxylation, anhydride formation and decarboxylation.

6. A hydrolysis product formed from a polar-modified rice husk wax as claimed in claim 1, wherein the hydrolysis is effected with metal oxides, metal hydroxides or metal carbonates.

7. An aqueous dispersion produced with a polar-modified rice husk wax as claimed in claim 1 or a derivatization product thereof.

8. A solvent-based dispersion produced with a polar-modified rice husk wax as claimed in claim 1 or a derivatization product thereof.

9. A lubricant additive in plastics comprising a polar-modified rice husk wax as claimed in claim 1 or a derivatization product thereof.

10. A dispersant for pigment masterbatch formulation for coloring of plastics comprising a polar-modified rice husk wax as claimed in claim 1 or a derivatization product thereof.

11. An adhesion promoter in composite materials composed of plastics and wood or plastics and glass fibers comprising a polar-modified rice husk wax as claimed in claim 1 or a derivatization product thereof.

12. A compatibilizer in blends of different plastics comprising a polar-modified rice husk wax as claimed in claim 1 or a derivatization product thereof.

13. A hotmelt adhesive comprising a polar-modified rice husk wax as claimed in claim 1 or a derivatization product thereof.

14. A solvent-containing paste comprising a polar-modified rice husk wax as claimed in claim 1 or a derivatization product thereof.

Description

EXAMPLES

[0028] The examples which follow are intended to illustrate the invention in detail, but without restricting it to specifically stated embodiments.

Examples 1-11

[0029] Modification of Ester Waxes with Maleic Anhydride

[0030] 500 g of the ester wax raw materials stated in table 1 were initially charged in a glass apparatus equipped with a stirrer system, internal thermometer, metering apparatus and distillation system under nitrogen and melted. At a temperature of 150 C., the stated amount of maleic anhydride was metered into the melt within 3 hours. At the same time, 7.5 g of di-tert-butyl peroxide were added dropwise from a dropping funnel. On completion of addition, the mixture was stirred at 150 C. for another 1 h and then, after applying reduced pressure (20 mbar), volatile compounds and unconverted maleic anhydride was distilled off.

TABLE-US-00001 TABLE 1 Analytical data of the ester waxes used and graft products thereof with maleic anhydride (MA) Ester wax used Amount Acid Hydrolysis Melt of MA number number Dropping viscosity used mg mg point at 90 C. % by Example Raw material KOH/g KOH/g C. mPa .Math. s wt.** 1 (inv.) Refined rice husk wax 8.1 88.2 78.2 17.3 9.0 2 (inv.)* Refined rice husk wax 8.1 88.2 78.2 17.3 9.0 3 (inv.)* Refined rice husk wax 8.1 88.2 78.2 17.3 9.0 4 (inv.) Refined rice husk wax 8.1 88.2 78.2 17.3 5.0 5 (inv.) Refined rice husk wax 8.1 88.2 78.2 17.3 13.0 6 (comp.) Licowax E 17.1 148.8 82.1 34.0 9.0 7 (comp.) Carnauba T1 prime 7.0 97.1 82.7 35.9 9.0 yellow 8 (comp.) Carnauba T3 light fatty 11.9 93.5 83.6 51.0 9.0 grey 9 (comp.) Deresinified sugarcane 18.3 117.0 83.7 97.3 9.0 wax 10 (comp.) Raw sugarcane wax 19.7 119.0 78.8 47.2 9.0 11 (comp.) Sunflower wax 2.8 103.0 79.3 14.0 9.0 Product Graft Acid yield*** Hydrolysis Melt number mg KOH/g/ number Dropping viscosity Gardner mg % by wt. mg point at 90 C. color Example KOH/g of MA KOH/g C. mPa .Math. s number 1 (inv.) 54.8 5.19 152.1 78.1 127.6 9.8 2 (inv.)* 54.9 5.20 150.4 79.1 130.0 9.3 3 (inv.)* 55.0 5.21 149.3 78.7 112.3 8.6 4 (inv.) 35.0 5.38 120.8 77.6 48.6 7.4 5 (inv.) 74.0 5.07 173.2 78.4 282.0 11.2 6 (comp.) 50.1 3.67 195.9 80.9 123.0 >18 7 (comp.) 34.0 3.00 123.9 81.9 167.2 17.5 8 (comp.) 33.8 2.53 134.0 81.9 186.5 >18 9 (comp.) 46.7 3.16 161.5 79.7 122.0 >18 10 (comp.) 57.9 4.24 167.8 79.4 219.3 >18 11 (comp.) 33.0 3.36 176.6 76.1 109.2 12.5 *Examples 2 and 3 are repetitions of example 1 and serve to verify reproducibility; **based on wax used; ***calc. as difference in product/reactant acid number based on MA used ( AN % by weight of MA).

[0031] Table 1 shows the indices of various ester waxes and the maleated graft products thereof. Acid and hydrolysis numbers rise with the use amount of maleic anhydride. The graft yields in the case of the inventive examples (rice husk wax) are much higher compared to the noninventive comparative examples. (An index used for the graft yield here is the rise in acid number per % by weight of maleic anhydride used.) Furthermore, the product colors, measured as the Gardner color number, are lighter.

Examples 12, 13

[0032] Hydrolysis and Saponification of Maleic Anhydride-Modified Refined Rice Husk Wax with Calcium Hydroxide

Example 12

[0033] In a 2 L beaker, 100 g of pulverized, maleic anhydride-modified refined rice husk wax (from example 1) were scattered into a dispersion of 19 g of calcium hydroxide in 510 mL of distilled water at 90 C. such that the temperature of the mixture never fell below 85 C. After filtration and drying at 80 C., the product was obtained as a yellow powder with an acid number of 32 mg KOH/g and a calcium content of 7.8% by weight.

Example 13

[0034] In a 7 L metal pot, 700 g of pulverized, maleic anhydride-modified refined rice husk wax (from example 1) were scattered into a dispersion of 266 g of calcium hydroxide in 5.0 L of distilled water at 90 C. such that the temperature of the mixture never fell below 85 C. The mixture was left to cool down to room temperature while stirring. After filtration and drying at 80 C., the product was obtained as a yellow powder with an acid number of 2.1 mg KOH/g and a calcium content of 13.0% by weight.

Examples 14-18

Production of Aqueous Anionic Dispersions

[0035] Dispersion was effected by melting the components specified in table 2 together while stirring at 120 C., adding boiling deionized water, stirring for a further 2 minutes and rapidly cooling (water bath) the dispersion obtained to room temperature.

[0036] The oleic acid content of the dispersions was matched to the acid number of the waxes used.

[0037] The solids content and the transparency of the dispersions were determined.

TABLE-US-00002 TABLE 2 Anionic dispersions Example [% by wt.] Component 14 (comp.) 15 (inv.) 16 (inv.) 17 (inv.) 18 (comp.) Refined rice husk wax 20.0 Example 4 20.0 (refined rice husk wax, grafted with 5% MA) Example 1 20.0 (refined rice husk wax, grafted with 9% MA) Example 5 20.0 (refined rice husk wax, grafted with 13% MA) Example 8 20.0 (Carnauba T3, grafted with 9% MA) Oleic acid 6.7 3.9 1.6 4.1 Diethylaminoethanol 3.10 3.10 3.10 3.10 3.1 Hot deionized water 70.20 73.00 75.30 75.9 72.80 Appearance milky, viscous, yellowish, yellowish, light brown, dark brown, coarse dispersion slightly cloudy opaque very finely cloudy divided Transparency after 0.0 13.5 19.4 22.4 5.0 3 weeks [%] Transparency is a measure of the fineness of the dispersion. Finely dispersed wax dispersions are more stable and lead, for example, to elevated imparting of shine in care products.

TABLE-US-00003 TABLE 3 Gloss and sliding friction of the self-shine dispersions Example [% by weight] Underlying wax in the 19 20 21 22 Component anionic dispersion (comp.) (inv.) (inv.) (inv.) Deionized water 48.1 46.7 45.0 45.5 Tris(2-butoxyethyl) 1.8 1.8 1.8 1.8 phosphate EDG 2.6 2.6 2.6 2.6 Ammonia 0.1 0.1 0.1 0.1 Licomer M 55 35.8 35.8 35.8 35.8 Ex. 14 Refined rice husk wax 7.5 Ex. 15 Refined rice husk wax, 8.8 grafted with 5% MA Ex. 16 Refined rice husk wax, 10.6 grafted with 9% MA Ex. 17 Refined rice husk wax, 10.0 grafted with 13% MA Syncera LP 1476, 30% 3.1 3.1 3.1 3.1 Genapol X-080 0.8 0.8 0.8 0.8 Silco FLW L-137 0.1 0.1 0.1 0.1 Saniprot 94-08 0.1 0.1 0.1 0.1 Gloss (black paper) 56 GU 90 GU 89 GU 88 GU Coefficient of 0.54 0.60 0.65 0.71 sliding friction

[0038] The self-shine dispersions were produced by blending the components listed in tab. 3. The dispersions were applied to black paper (test card, Simex GmbH) with a 24 m coating bar. After drying, coefficients of sliding friction and gloss were determined. The coefficients of sliding friction (and hence the slip resistances) of the products of the invention are much higher than in the case of unmodified rice husk wax; they rise with the proportion of grafted maleic anhydride content. The dispersions of the modified rice husk waxes show improved gloss compared to the unmodified starting material.

Examples 23, 24

Production of Aqueous Nonionic Dispersions of the Waxes of the Invention

[0039] Dispersion was effected by melting the components stated in table 4 together while stirring at 120 C., adding boiling deionized water, stirring for a further 2 minutes and rapidly cooling (water bath) the dispersion obtained to room temperature.

[0040] The dispersions were applied to black paper (test card, Simex GmbH) with a 24 m coating bar. After drying, the gloss and coefficients of sliding friction were determined.

TABLE-US-00004 TABLE 4 Nonionic dispersions Example [% by wt.] Component 23 (comp.) 24 (inv.) Refined rice husk wax 10.4 Example 1 10.4 (refined rice husk wax, grafted with 9% MA) Wax emulsifier 4106 3.0 3.0 Deionized water 86.6 86.6 Appearance not dispersible light brown, very finely divided Gloss (black paper) 65.7 GU Coefficient of sliding 0.80 friction

[0041] The nonionic dispersion of refined rice husk wax according to the formulation specified in table 4 was not possible. The polar-modified variant had good dispersibility.

Examples 25-31

Production of Hotmelt Adhesives

[0042] Using the waxes listed in table 5, hotmelt adhesives were produced. For this purpose, mixtures of 15.0 g of Engage 8407, 15.0 g of Licocene PP 1502, 30.0 g of Sukorez SU-90, 30.0 g of Licowax PE 520 and 10.0 g of the respective test waxes were melted and stirred at 170 C. for one hour.

[0043] Example 25 describes a standard formulation that finds wide use in the bonding of cardboard packaging.

[0044] Examples 26-28 show examples in which the waxes of the invention were used as test waxes. For comparative examples 29-31, noninventive modified ester waxes were used.

[0045] For assessment of the properties, tensile strength, open time and setting time were determined.

TABLE-US-00005 TABLE 5 Hotmelt adhesives Melt Tensile shear viscosity strength Open Setting at 150 C. wood/wood time time Example Wax used mPa .Math. s MPa s s 25 (comp.) Semi Hard Micro 75 3498 1.7 <2 2 26 (inv.) Example 4 3374 2.5 8 2 (refined rice husk wax, grafted with 5% MA) 27 (inv.) Example 1 2771 2.5 7 2 (refined rice husk wax, grafted with 9% MA) 28 (inv.) Example 5 3525 3.2 <2 2 (refined rice husk wax, grafted with 13% MA) 29 (comp.) Example 11 4653 1.9 <2 6 (deresinified sugarcane wax, grafted with 9% MA) 30 (comp.) Example 12 4602 1.4 <2 2 (raw sugarcane wax, grafted with 9% MA) 31 (comp.) Example 9 3948 2.0 <2 2 (Carnauba T1, grafted with 9% MA)

[0046] The hotmelt adhesives of the invention show higher tensile shear strengths, which improves the stability of the bonds. Higher open times, especially in the case of manual adhesive bonding or in the event of a brief machine shutdown, have the advantage that the hotmelt adhesive does not cure before the parts to be bonded can be brought together. This is particularly advantageous when the setting time remains short at the same time.

Raw Materials Used:

[0047] Refined rice husk wax is a bleached and purified rice husk wax from Shengtao having the following indices:

[0048] Acid number: 8.1 mg KOH/g

[0049] Hydrolysis number: 88.2 mg KOH/g

[0050] Hydroxyl number: 15.5 mg KOH/g

[0051] Dropping point: 78.2 C.

[0052] Melt viscosity (100 C.): 17.3 mPa.Math.s

[0053] Licowax E is a chromosulfuric acid-oxidized and ethylene glycol-esterified montan wax from Clariant Produkte (Deutschland) GmbH having the following indices:

[0054] Acid number: 18.0 mg KOH/g

[0055] Hydrolysis number: 148.8 mg KOH/g

[0056] Dropping point: 82.1 C.

[0057] Melt viscosity (100 C.): 34.0 mPa.Math.s

[0058] Carnauba T1 is a natural ester wax obtained from the leaves of carnauba palms from Ter Hell & Co. GmbH (Carnaubawax T1 primeyellow) having the following indices:

[0059] Acid number: 7.0 mg KOH/g

[0060] Hydrolysis number: 97.1 mg KOH/g

[0061] Dropping point: 82.7 C.

[0062] Melt viscosity (100 C.): 35.9 mPa.Math.s

[0063] Carnauba T3 is a natural ester wax obtained from the leaves of carnauba palms from Ter Hell & Co. GmbH (Carnaubawax T3 light fatty grey) having the following indices:

[0064] Acid number: 11.9 mg KOH/g

[0065] Hydrolysis number: 93.5 mg KOH/g

[0066] Dropping point: 83.6 C.

[0067] Melt viscosity (100 C.): 51.0 mPa.Math.s

[0068] Sunflower wax is a purified wax obtained from sunflower oil from Lohia Brothers Private Ltd. (Sun flower wax Grade H A 1) having the following indices:

[0069] Acid number: 2.8 mg KOH/g

[0070] Hydrolysis number: 102.0 mg KOH/g

[0071] Dropping point: 79.3 C.

[0072] Melt viscosity (100 C.): 14.0 mPa.Math.s

[0073] Raw sugarcane wax is a wax obtained from sugarcane bagasse from Deurex AG (Deurex X 50) having the following indices:

[0074] Acid number: 19.7 mg KOH/g

[0075] Hydrolysis number: 119.0 mg KOH/g

[0076] Dropping point: 78.8 C.

[0077] Melt viscosity (100 C.): 47.2 mPa.Math.s

[0078] Deresinified sugarcane wax was produced by extraction of the raw sugarcane wax Deurex X 50 with dichloromethane as follows: 200 g of Deurex X 50 and 400 g of ethanol were initially charged and heated to boiling for 1 h. Subsequently, the mixture was cooled down to 50 C. and the stirrer was switched off. The ethanol phase was separated from the solidified wax by filtration. The wax was washed with 100 g of ethanol at 45 C. 11.0 g of a brown residue (resin) were obtained from the ethanol phase. The wax was dried under reduced pressure and 183.5 g of a light brown wax (deresinified sugarcane wax) were obtained with the following indices:

[0079] Acid number: 18.3 mg KOH/g

[0080] Hydrolysis number: 117.0 mg KOH/g

[0081] Dropping point: 83.7 C.

[0082] Melt viscosity (90 C.): 97.3 mPa.Math.s

[0083] Licomer M 55 is an aqueous styrene-acrylate copolymer dispersion from Michelman, Inc.

[0084] Syncera LP 1476 is an aqueous emulsion of LDPE and paraffin wax from Paramelt B.V.

[0085] Genapol X-080 is a fatty alcohol ethoxylate from Clariant Produkte (Deutschland) GmbH.

[0086] Silco FLW L-137 is a leveling additive from Silcona GmbH & Co. KG.

[0087] Saniprot 94-08 is an antimicrobial additive from Clariant Produkte (Deutschland) GmbH.

[0088] Wax emulsifier 4106 is a fatty alcohol ethoxylate mixture from Clariant Produkte (Deutschland) GmbH.

[0089] Engage 8407 is an ethylene/1-octene copolymer from Dow Chemical.

[0090] Licocene PP 1502 is a metallocene polypropylene wax from Clariant Produkte (Deutschland) GmbH with the following indices:

[0091] Softening point: 86.0 C.

[0092] Melt viscosity (170 C.): 1760 mPa.Math.s

[0093] Sukorez SU-90 is a hydrogenated dicyclopentadiene resin from Kolon Hydrocarbon Industries.

[0094] Licowax PE 520 is a polyethylene wax from Clariant Produkte (Deutschland) GmbH with the following indices:

[0095] Dropping point: 119.2 C.

[0096] Melt viscosity (140 C.): 562 mPa.Math.s

[0097] Semi hard micro 75 is a paraffin wax from Paramelt B.V. with the following indices:

[0098] Dropping point: 75.0 C.

Determination of the Chemical and Physical Indices:

Acid Number:

[0099] The acid number is determined according to DIN EN ISO 2114.

Hydrolysis Number:

[0100] The hydrolysis number is determined according to DIN EN ISO 3681.

Dropping Point:

[0101] The dropping point is determined according to DIN 51801/2.

Softening Point:

[0102] The softening point is determined according to ASTM D36.

Melt Viscosity:

[0103] The melt viscosity is determined according to DIN 53019 with a rotary viscometer as follows:

[0104] The wax melt to be examined is present in an annular gap between two coaxial cylinders, one of which rotates at constant speed (rotor), the other being at rest (stator). What is determined is the torque whichat a given speedis needed to overcome the friction resistance of the liquid in the annular gap. The geometric dimensions of the system and the torque and speed values determined can be used to calculate the shear stress that exists in the liquid and the shear rate and hence the viscosity.

Gardner Color Number:

[0105] The Gardner color number is determined according to ISO 4630-2 as follows:

[0106] The wax to be examined is heated in a test tube (diameter 11 mm, Dr. Lange, Germany) and in an aluminum block. Immediately after a clear melt has formed, the Gardner color number is determined with a Lico 500 colorimeter (Dr. Lange, Germany).

Calcium Content:

[0107] The calcium content is determined in accordance with DGF-M-IV 4 (63) (Deutsche Einheitsmethoden zur Untersuchung von Fetten, Fettprodukten, Tensiden and verwandten Stoffen [German Uniform Methods for Analysis of Fats, Fat Products, Surfactants and Related Substances]).

[0108] In a 150 mL beaker, 2.0 g of the wax sample are dissolved in 60 mL of a xylene/ethanol mixture (10:1 [v/v]). The solution is titrated with 0.5 M ethanolic HCl solution up to the steepest gradient (DL 53 titrator, Mettler, DGi113-SC pH electrode). The calcium content is calculated by the formula:

Ca %[m/m]=(V [mL]c [mol/L]M [g/mol]T100%)/W [g]1000 mLN

[0109] where

[0110] V is consumption of HCl solution

[0111] c is concentration of the HCl solution

[0112] M is molecular weight of calcium

[0113] T is titre of the HCl solution

[0114] W is weight of the wax sample

[0115] N is (normality of the HCl compared to calcium ions).

Solids Content:

[0116] The solids content is determined with a halogen moisture analyzer (HB43, Mettler Toledo).

Transparency:

[0117] The wax dispersion is introduced into a round cuvette (diameter 11 mm) and the transparency is determined at 20 C. with a colorimeter (Lico 500 colorimeter, from Dr. Lange).

Gloss:

[0118] The gloss is determined according to DIN EN ISO 2813 with a reflectometer (micro-TRI-gloss from Byk Gardner) at a measurement angle of 60. The measurement result is reported in the unit GU (gloss units).

Coefficient of Sliding Friction:

[0119] The coefficient of sliding friction is determined with a friction peel tester, model 225-1, from the Thwing-Albert Instruments Company in accordance with ASTM Method D2534. For this purpose, a paper coated with the wax dispersion to be tested is applied to the analysis system. Subsequently, a leather-covered metal sledge (349 g) is placed onto the coated surface. The sledge is then pulled over the coated paper surface at constant speed (15 cm/min). The force required for the pulling of the sledge is measured. Since it is the dynamic coefficient of sliding friction that is being determined, the initial force which is required to set the sledge in motion can be neglected.

Tensile Shear Strength:

[0120] The tensile shear strength is determined according to DIN EN 1465 as follows:

[0121] The molten hotmelt adhesive is applied with a spatula over the area of a test specimen (from Rokoll GmbH, 100200.5 mm, steamed beechwood test specimens, planed surface) at 170 C., and joined to a second test specimen of identical design over an overlap length of 20 mm. After cooling, the sample is stored at room temperature for 7 days. Subsequently, the tensile shear strength is determined (Z010 tensile tester from Zwick/Roell; pulling speed: 50 mm/min; clamped length: 115 mm; measurement length: 50 mm).

Open Time:

[0122] The open time is determined at 170 C. with a 500 m bar-coated melt film on an uncoated cardboard surface. For this purpose, paper strips (15 cm) are pressed onto the cooling melt film every second. After the hotmelt adhesive has cured completely, the paper strips are pulled off. When the fibers do not break out completely at the bonding site, the end of the open time has been reached.

Setting Time:

[0123] To determine the setting time, a bead of the hotmelt adhesive is applied to a paper strip (1.512 cm) and a second paper strip is pressed on with an overlap. After the given time, the strips are pulled apart. If the papers can be detached from one another without complete tearing of the fibers, the setting time has not yet been attained and another experiment is conducted, in which the time before the papers are pulled apart is increased by 1 s. If there is complete tearing of the fibers, the setting time has been attained.