GB/T 8146-2003 English PDF (GBT8146-2003)

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GB/T 8146-2003: Test methods for rosin
GB/T 8146-2003
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 65.050
B 72
Replacing GB/T 8146-1987
Test Methods for Rosin
ISSUED ON: JUNE 17, 2003
IMPLEMENTED ON: DECEMBER 01, 2003
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Determination of Colour and Appearance ... 5
4 Determination of Softening Point (Ring-and-Ball Method) ... 7
5 Determination of Acid Value ... 11
6 Determination of Unsaponifiable Matter ... 13
7 Determination of Ethanol Insoluble Matter ... 15
8 Determination of Ash... 16
Appendix A (Normative) Judgment of Crystallization Phenomenon and
Qualitative Method of Sulfur Content ... 18
Test Methods for Rosin
1 Scope
This Standard specifies the inspection methods for the colour, appearance, softening
point, acid value, unsaponifiable matter, ethanol insoluble matter, and ash of rosin.
This Standard is applicable to the inspection of rosin.
2 Normative References
The provisions in following documents become the provisions of this Standard through
reference in this Standard. For dated references, the subsequent amendments
(excluding corrigendum) or revisions do not apply to this Standard, however, parties
who reach an agreement based on this Standard are encouraged to study if the latest
versions of these documents are applicable. For undated references, the latest edition
of the referenced document applies.
GB/T 601 Chemical Reagent - Preparations of Standard Volumetric Solutions
3 Determination of Colour and Appearance
3.1 Colour grading
The colour grading of rosin uses rosin chromaticity standard blocks, each set has a
total of six glass standard colour blocks. A set of rosin chromaticity standard device No.
S20 preserved by the Institute of Chemical Industry of Forest Products CAF stipulates
as the color grading standard of rosin chromaticity standard block; the chromaticity
index of 1931 standard chromaticity system of the International Commission on
Illumination (CIE) for all grades of colours is shown in Table 1.
3.2.3 Other colorimeters
The inspection of rosin colour shall be based on the rosin chromaticity standard block
as the grading standard. It is allowed to use other colorimeters whose colorimetric
effect is equivalent to that of the chromaticity standard block after being checked by
the chromaticity standard block.
3.3 Determination of appearance
Under indoor natural light or normal lighting conditions, horizontally place one
observation surface of the sample block used to determine the colour grade made
according to 3.2.1 on an ordinary newspaper; and observe downward from the other
observation surface, if it can read the No.5 printed font clearly, it is transparent;
otherwise, it is opaque.
4 Determination of Softening Point (Ring-and-Ball
Method)
4.1 Summary of the method
Rosin has no fixed melting point and becomes soft when heated. Fill two copper rings
of specified thickness and diameter with rosin; respectively place a steel ball of
specified mass and diameter on the ironed rosin through a positioner; and then heat it
in a heating medium at a certain temperature-rise speed; then the instantaneous
temperature at which the rosin wrapped with steel ball falling a fixed distance is the
softening point of the rosin.
4.2 Apparatus
4.2.1 The softening point tester, the device is shown in Figure 1; and the main parts
are shown in Figure 2.
4.2.6 Thermometer, internal standard type, immersion height of 55mm, tail length of
100mm, scale range of 30°C~100°C, minimum graduation of 0.2°C, mercury bulb outer
diameter of 5.0mm±0.5mm, mercury bulb length of 8mm ±2mm, and total length of
380mm±10mm.
4.2.7 Beaker with the capacity of about 800 mL, the diameter of 90mm, and the height
of no less than 140mm.
4.2.8 Stirrer, generally manual stirrer is used, mechanical stirrer or electromagnetic
stirrer may also be used. When stirring, the speed shall be uniform and shall not form
a vortex, vibration or air bubbles.
4.3 Heating medium
4.3.1 Freshly boiled distilled water
Put about 800 mL of ordinary distilled water into a 1000 mL beaker and heat it to boiling;
and then cool it to 35°C below. Then it is used for the determination of rosin samples
with a softening point no greater than 80°C.
4.3.2 Glyceryl (glycerol)
It shall be analytically pure, which comply with GB/T687. It is used for the determination
of rosin samples with a softening point greater than 80°C. Repeated use shall not affect
the determination results.
4.4 Operation method
4.4.1 Once-melt specimen shall be used for two parallel determinations under the
same conditions.
4.4.2 Take about 5g of rosin and crush into a diameter of about 5mm in a container;
slowly heat it to melt at the possible lowest temperature to avoid bubbles and smoke.
Pour the molten rosin into the preheated ring on the copper plate immediately. When
the rosin is completely solidified, gently remove the copper plate. The ring shall be full
of rosin; and the surface shall be slightly raised. Use an electric iron to iron it out for
inspection. If the rosin in the ring has sunken or bubbles, it shall be remade.
4.4.3 Put the prepared specimen ring on the ring frame plate; install the steel ball
positioner on the ring; and then put the steel ball into the centre of the steel ball
positioner. Then insert the thermometer from the top cover of the ring frame; so that
the bottom of the mercury ball and the bottom surface of the ring are on the same
plane; and then put the entire ring frame into an 800mL beaker. After the above device
is completed, pour the freshly boiled distilled water into the beaker; so that the upper
surface of the ring frame plate is kept at 51mm from the water surface. After standing
for 10min; use an adjustable electric furnace or other heat source to heat the water to
Dissolve 33g of potassium hydroxide (comply with GB/T 2306, analytically pure) in a
small amount of distilled water without carbon dioxide; add this distilled water to dilute
to 1000mL; and mix well. The working standard reagent potassium hydrogen phthalate
(comply with GB 1257) is used as the reference substance; and calibrate according to
the calibration method of 0.5mol/L sodium hydroxide standard titration solution
specified in GB/T 601, and accurate to 0.001 mol/L.
5.3 Operation method
5.3.1 Make parallel determinations of two portions of test materials.
5.3.2 Remove the outer part of the rosin and crash it; immediately take 2g of the
specimen (accurate to 0.001g) into a 250mL conical flask; add 50mL of neutral ethanol
to dissolve it (if necessary, heat on a water bath to make the entire specimen, then let
it cool); add 5 drops of phenolphthalein indicator; and then titrate with 0.5mol/L
potassium hydroxide standard titration solution until the reddish colour does not fade
for 30s.
5.4 Calculation of results and report
5.4.1 Calculation
The acid value is calculated by the mass fraction wn of potassium hydroxide (KOH),
expressed in mg/g; and it shall be calculated according to Formula (1):
Where:
V – value of volume of potassium hydroxide standard titration solution (5.2.3), in mL;
c – accurate value of the concentration of potassium hydroxide standard titration
solution, in mol/L;
m – value of mass of the test materials, in g;
M – value of molar mass of the potassium hydr...