Abstract:
Determination of &#34;dry rubber content&#34; (DRC) within a latex solution. Particularly, a volumetric analysis device, including an elongated chamber with a removable filter cap positioned at one end. A compression plunger is mounted within the chamber upon one end of an axially reciprocable shaft. A compression handle and dial drum scale are mounted at that other end of the shaft, which extends through the chamber end wall. A liquid flocculating agent is mixed with a measured volume of latex solution within the chamber, then compressed by actuating the plunger. During compression, the liquid residue is urged through the filter cap. The remaining batch of precipitated latex is measured as the &#34;dry rubber content&#34;, accordingly as the exterior dial drum intersects a reference scale on the cylinder interior.

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     Determination of the dry rubber content (DRC) in a precipitated latex solution. 
     Hevea brasiliensis is a biological product of very complex composition. Besides rubber hydrocarbon, it contains many proteinous and resinous substances, carbohydrates, inorganic matter and water. The following figures are typical for a freshly tapped sample of natural rubber latex: 
     
         ______________________________________           %______________________________________Total solids content             22-48Dry rubber cement 20-45Proteinous substances             1.5Resinous substances             2Carbohydrates     1Inorganic matter  0.5______________________________________ 
    
     The dry rubber content (DRC) of field latex, like other chemical compounds of the latex, varies according to season, weather, soil condition, clone, stimulation program and tapping system, etc. Dilution of the latex with water or preservatives also alters the DRC. The DRC of field latex normally falls in the range of 20-45% and 35% is generally taken as the average figure for plantation field latex. 
     (2) Description of the Prior Art 
     Prior art methods of determining DRC in a latex composition include: 
     (A) The Standard Laboratory Method 
     Based on Malyasian Standard MS 3:35:1975, wherein the known weight of field latex is acid coagulated and the wet latex coagulant is dried overnight in an oven at 70° C. before reweighing. 
     (B) The &#34;Chee&#34; Method 
     A simplified version of the Standard Laboratory Method, using a calibrated dipper and a simple balance for weighing the dried test piece. A kerosene oven may be used. 
     (C) The Hydrometric Method 
     Mixing one part of field latex with two parts of water and reading the specific gravity of the resultant mixture, using a latex hydrometer. 
     A description of the foregoing techniques appears in &#34;Dry Rubber Content Determination Competition&#34;, undated, (Malaysian Rubber Research Development Board, Natural Rubber Building, 150 Jalan Ampang, Kuala Lumpur, Malaysia). 
     Prior art searching has developed: 
     HORNER U.S. Pat. No. 2,296,852 
     ANWAY U.S. Pat. No. 2,325,026 
     ANWAY U.S. Pat. No. 2,325,027 
     HORNER U.S. Pat. No. 2,327,642 
     BASHORE U.S. Pat. No. 2,482,147 
     COOK U.S. Pat. No. 2,691,298 
     HEUER, JR., et al. U.S. Pat. No. 3,199,341 
     These patents are discussed in a separate Prior Art Statement. 
     SUMMARY OF INVENTION 
     According to the present invention, the latex solution is treated with a liquid flocculating agent so as to produce natural rubber particulation. Then, a measured amount of the solution is introduced into the dry rubber content (DRC) determinator which is in the form of an elongated chamber, having a removable filter cap positioned at one end. A compression plunger is mounted upon an axial shaft which is reciprocably positioned within the cylinder. The cylinder includes an exterior reference scale and a dial drum affixed to a portion of the shaft extending through the other end of the chamber. The compression plunger may be urged to compress the measured batch of precipitated latex solution contained within the cylinder, while urging liquid residue through the filter cap. Thus, the determinator measures the DRC, as the volume of precipitated latex, per unit sample of solution. A standard of compression may be prefixed upon the exterior reference scale, so as to eliminate operator error. In addition, the scale may be calibrated for standard resiliency of natural latex in dynes/cc. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation, partially in section, showing the elongated chamber, with the axial shaft and compression plunger in fully compressed position, such that the plunger abuts the filter cap. 
     FIG. 2 is an end elevation, showing superpositioning of the dial drum with respect to the exterior reference scale and the cylinder exterior. 
     FIG. 3 is a fragmentary vertical section taken through the closed end of the cylinder, showing the clutch mechanism. 
     FIG. 4 is a fragmentary side elevation partially in section, showing the elongated chamber with the axial shaft and compression chamber in retracted position, prior to introducing the precipitated latex solution. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In FIG. 1 there is illustrated a volumetric analysis cylinder 10, having a removable filter cap 24, which supports inner screen filter 22 in juxtaposition with axially extending micropore outlets 26. 
     Pressure plunger 18, which may be formed from a soft plastic product, such as that trademarked &#34;Teflon&#34; and manufactured by E.I. DuPont de Nemours, may be secured to an axially extending feed screw shaft 12 by means of thrust bearing 16 or the like. Feed screw shaft 12 may have a feed shaft cap 30 and extend outwardly of cylinder 10, so as to engage drive clutch assembly 36. A felt shield 34 may be interposed between the drive clutch housing 44 and dial drum assembly 28, which encircles cylinder 10 and is coextensive therewith. Dial drum 28 may include a plurality of graduated markings, for example, 100 markings in the 360° area, as illustrated in FIG. 2. Longitudinal reference scale 14 may be positioned upon the exterior of cylinder 10, such that the bottom edge or open end of the dial drum 22 intercepts a milliliter reading upon scale 14, as compression of the latex composition is completed. A handle 38, including knobs 60, 62 may be secured to the drive clutch assembly by means of conventional bolts 64. A shaft lock screw 40 may be employed to secure the clutch assembly housing 36 to drive shaft 12. 
     As illustrated in FIG. 3, a washer may be interposed between the lockscrew 40 and the housing 36. A pair of pressure plates 42 may abut the dial drum 28 at the open end of clutch drive cover 44. Drive plate 48, and shaft pads 50, encircle the end of shaft 12 within housing 44. A slip pad 52 may abut clamp pad 46 adjacent bearing 54. A plurality of set screws 58 may engage clamp pad 46. 
     Current methods for determining the Dry Rubber Content (DRC&#34;) of Hevea brasiliensis either by laboratory analysis, the &#34;Chee&#34; Method or hydrometric analysis fail to meet either the degree of accuracy or time requirement that can be met by using the present invention, together with standard volumetric methods for determining the volume of precipitated coagulate per unit volume of solution in a given sample. 
     The suggested test instrument will accurately measure the volume of precipitated latex per unit sample of solution, using a standard of compression that is prefixed upon reference scale 14, so as to eliminate operator error. Reference scale 14 is calibrated for the standard resiliency of natural latex in dynes/cc and is unalterable in the field. 
     The reference scale is read by the operator and is external to the compression of the latex within the cylinder. 
     The instrument is adjusted to read within 0.1541% within the 20 to 45% range for DRC of field latex inclusive of proteinous, resinous and other inorganic matter common in field latex to a total of 5% of the total sample. 
     Together with each instrument there may be provided a Data Table (see below), which is easily read and is descriptive of the analysis of the sample. These results are obtainable within two minutes. 
     CLUTCH DRIVE 
     1. Turning handle 38 drives feed screw shaft 12 through clutch assembly 36. 
     2. When selected pressure against plunger 18 has been achieved, shaft pads 50 allow slippage of drive plates 48 to occur. Drive plates 48 are keyed to clutch housing cover 44 by 0.060&#34; radius tabs. Shaft pads 50 are keyed to drive shaft 12. 
     3. Slippage between shaft pads 50 and drive plates 48 is established through pressure against clamp pad 46 by means of set screws 58. 
     4. Adjustment of set screws 58 may be made only after removal of handle 38 from clutch housing 44. 
     5. When pressure against pressure plunger 18 becomes greater, than the friction of the clutch setting, dial drum 28 will rotate around cylinder 10, but will not advance along reference scale 14. 
     6. Drive clutch 36 and dial drum 28 rotate about bearing surfaces on feed screw shaft 12. 
     DETERMINATION OF DRY RUBBER CONTENT (DRC) 
     1. Coagulation precipitation of the solids in field latex solution may take place within volumetric steel cylinder 10. 
     2. The standard measured volume of latex is taken with a conventional &#34;Teflon&#34; beaker of 250 ml. Total capacity ±0.05%. 
     3. This volume is mixed with 250 ml of precipitating coagulant solution within cylinder 10 to a total volume of 500 ml. ±0.05%. 
     4. Filter cap 24 is secured upon cylinder 10, which is shaken, and torque handle 38 is turned by means of knobs 60, 62 until no further compression of the latex batch is possible. 
     5. The reading of dial drum 28 open end on reference scale 14 is taken to 1 mm and the corresponding values found in Data Table I, below. 
     6. Data Table I is based upon statistical data for natural latex and is within proscribed limits. The total extraneous solids should not exceed 5% of the total sample or 12.5 ml (6.16 mm) of the adjusted gross sample. Data Table I reflects this total of 5% extraneous solids, and represents only 5% for the total 250 ml sample. Consistency is repeatable for each sample and therefore corrected in each reading in the Data Table. Since the instrument reads to 1 mm (2.0922 ml), this is an error of only 0.008 or 0.1% for the 12.5 ml of the 250 ml sample. The Data Table reflects the DRC value, as corrected for both extraneous solids (5% maximum) per sample and 0.1% for total analysis. 
     ADVANTAGES OF INSTRUMENT 
     Spurious additives would have to be added in such great quantity that the percentage of volume would immediately reflect adulteration of the sample being tested. The allowable 5% on which each and every sample is evaluated then becomes a standard, not to be exceeded. Such samples would be rejected or, if desired, retested. 
     Excessive water, dilution, or other materials added that would affect density in hydrometric analysis have no effect upon this method. 
     Results are reproducible within limits established and do not vary from sample to sample, since the instrument is calibrated to read within 0.2% of the test DRC sample. 
     The instrument is mechanical and does not require electricity. The suggested acid coagulation solution is safe and nontoxic. The instrument will give results for all types of Hevea brasiliensis. 
     The test is easily performed by anyone. The scale is marked upon the instrument and once the reading is taken from the instrument, the operator reads the DRC value directly from the accompanying Data Table. 
     Accuracy of the precipitated floc is protected by an especial precipitating acid solution. The use of unqualified acid reagents could and most likely would produce entrapment of non-compressible liquid fractions in the compression chamber. This would be immediately noticed by a reading far greater than possible for normal latex. 
     DATA PROVIDED IN DATA TABLE I 
     a. Readings in mm 
     b. Volume 
     c. Total percent of solids 
     d. Extraneous solids 
     e. DRC in percent of sample 
     
                       DATA TABLE I______________________________________READING            TOTAL    EXTRANEOUS DRCIN MM    VOLUME    SOLIDS   SOLIDS     %______________________________________1        2.09221   .836883  .10461     .7950392        4.18441   1.67377  .209221    1.590083        6.27662   2.51065  .313831    2.385124        8.36883   3.34753  .418441    3.180165        10.461    4.18441  .523052    3.975196        12.5532   5.0213   .627662    4.770237        14.6455   5.85818  .732273    5.565278        16.7377   6.69506  .836883    6.360319        18.8299   7.53195  .941493    7.1553510       20.9221   8.36883  1.0461     7.9503911       23.0143   9.20571  1.15071    8.7454312       25.1065   10.0426  1.25532    9.5404713       27.1987   10.8795  1.35993    10.335514       29.2909   11.7164  1.46455    11.130515       31.3831   12.5532  1.56916    11.925616       33.4753   13.3901  1.67377    12.720617       35.5675   14.227   1.77838    13.515718       37.6597   15.0639  1.88299    14.310719       39.7519   15.9008  1.9876     15.105720       41.8441   16.7377  2.09221    15.900821       43.9364   17.5745  2.19682    16.695822       46.0286   18.4114  2.30143    17.490923       48.1208   19.2483  2.40604    18.285924       50.213    20.0852  2.51065    19.080925       52.3052   20.9221  2.61526    19.87626       54.3974   21.759   2.71987    2.67127       56.4896   22.5958  2.82448    21.46628       58.5818   23.4327  2.92909    22.261129       60.674    24.2696  3.0337     23.056130       62.7662   25.1065  3.13831    23.851231       64.8584   25.9434  3.24292    24.646232       66.9506   26.7803  3.34753    25.441233       69.0428   27.6171  3.45214    26.236334       71.135    28.454   3.55675    27.031335       73.2273   29.2909  3.66136    27.926436       75.3195   30.1278  3.76597    28.624437       77.4117   30.9647  3.87058    29.416438       79.5039   31.8016  3.97519    30.211539       81.5961   32.6384  4.0798     31.006540       83.6883   33.4753  4.18441    31.801641       85.7805   34.3122  4.28902    32.596642       87.8727   35.1491  4.39364    33.391643       89.9649   35.986   4.49825    34.186744       92.0571   36.8228  4.60286    34.981745       94.1493   37.6597  4.70747    35.776746       96.2415   38.4966  4.81208    36.571847       98.3337   39.3335  4.91669    37.366848       100.426   40.1704  5.0213     38.161949       102.518   41.0073  5.12591    38.956950       104.61    41.8441  5.23032    39.751951       106.703   42.681   5.33513    40.54752       108.795   13.5179  5.13974    11.34253       110.887   44.3519  5.54135    12.137154       112.979   45.1917  5.61896    12.932155       115.071   46.0286  5.75357    43.727156       117.164   46.8654  5.85818    44.522257       119.256   47.7023  5.96279    45.317258       121.348   48.3392  6.0674     46.112259       123.44    49.3761  6.17201    46.907360       125.532   50.213   6.27662    47.702361       127.625   51.0499  6.38123    48.497462       129.717   51.8867  6.48584    49.292463       131.809   52.7236  6.59015    50.087464       133.901   53.5605  6.69506    50.882565       135.993   54.3974  6.79967    51.677566       138.086   55.2343  6.90428    52.472667       140.178   56.0712  7.00889    53.267668       142.27    56.908   7.1135     54.062669       144.362   57.7449  7.21812    54.837770       146.455   58.5818  7.32273    55.652771       148.547   59.4187  7.42734    56.447872       150.639   60.2556  7.53195    57.242873       152.731   61.0925  7.63656    58.037874       154.823   61.9293  7.74117    58.832975       156.916   62.7662  7.84578    59.627976       159.008   63.6031  7.95039    60.422977       161.1     64.44    8.055      61.21878       163.192   65.2769  8.15961    62.01379       165.284   66.1138  8.26422    62.808180       167.377   66.9506  8.36883    63.603181       169.469   67.7875  8.47344    64.398182       171.561   68.6244  8.57805    65.193283       173.653   69.4613  8.68266    65.988284       175.745   70.2982  8.78727    66.783385       177.838   71.135   8.89188    67.578386       179.93    71.9719  8.99649    68.373387       182.022   72.8088  9.1011     69.168488       184.114   73.6457  9.20571    69.963489       186.206   74.4826  9.31032    70.758590       188.299   75.3195  9.41493    71.553591       190.391   76.1563  9.51954    72.348592       192.483   76.9932  9.62415    73.143693       194.575   77.8301  9.72876    73.938694       196.667   78.667   9.83337    74.733695       198.76    79.5039  9.93798    75.528796       200.852   80.3408  10.0426    76.323797       202.944   81.1776  10.1472    77.118898       205.036   82.0145  10.2518    77.913899       207.129   82.8514  10.3564    78.7088100      209.221   83.6883  10.461     79.5039______________________________________ 
    
     SUGGESTED TEST EQUIPMENT 
     I. DRC Micro-sample Caliper Instrument: 
     Allows for agitation/coagulation of a fixed sample (0.5L) 250 ml coagulation solution and 250 ml of latex. 
     Liquid is extracted by compression filtration and the solid content measured between 20 and 50% of the final volume of 250 ml latex, on a fixed expanded scale 14. 
     II. Disposable Micro-filters: 
     Standard millipore filters 22 provide for liquid extraction and retention of solids. 
     III. Coagulation-Acid solution: 
     An organic acid solution for floc precipitation of latex is initialized, so as to prevent entrapment of non-compressible liquid fractions. 
     IV. Laminated DRC Chart (Data Table I): 
     Data is read directly from chart and excessive volume of DRC or adulteration will be immediately noticed, since this is reflected as a percent of extraneous solids based on the 250 ml sample volume being 100% of the total. 
     V. Field Test Kit--optional: 
     A rapid detection method (not described) may utilize color change to indicate excessive presence of adulterants. 
     SAMPLE ANALYSIS: 
     Computational Data of Instrumentation: 
     Measured Volume of Cylinder=500 ml=0.5L±0.05% 
     Diameter (ID)=5.161 cm 
     Radius=2.580 cm 
     Volume per linear mm=2.0922 ml/mm 
     Length of Measured Volume=23.89 cm 
     Volume as a percentage per ml volume=0.0083, 83% 
     A sample of raw latex is subjected to analysis by mixing in the compression cylinder with 250 ml of acid-coagulation solution. The exact measured volume of latex is obtained by a &#34;Teflon&#34;-coated steel beaker. The beaker is filled and leveled by spatula, leaving 250 ml±0.005%. The instrument handle is turned until compression stops, leaving the indicator at the 42 mm mark on the sleeve. 
     Since 42 mm×2.09222 ml/mm=87.8732 cc solids (total) and if 5% (IS) extraneous solids then 5%=4.39364 cc. 87.8732-4.39364=83.47906 cc/250 cc=0.333916 THEREFORE: 0.333916×100=33.3916 percent DRC 
     1. Obtained reading is 42 mm 
     2. Find 42 mm on Data Table 
     Find reading of DRC across from 42 mm under DRC 
     4. Note extraneous solids=4.39364 cc of total.