JPH08136504A - Friction electrification sequence determination method for powder - Google Patents

Abstract

(57) [Summary] [Purpose] To accurately determine the triboelectric charge train between toners and the triboelectric charge train between carriers. [Structure] With a developer in which the same toner is combined with different carriers, the relationship between the toner charge amount and the toner mixture ratio (toner weight / carrier weight) is measured, and the value of the charge amount when the toner mixture ratio is 0 is obtained. . The carrier having a large value has a large work function, and it can be determined that the triboelectric charge train is on the negative side. [Effect] It is possible to determine the triboelectrification series between powders that cannot be distinguished by color.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining a triboelectric charge train of powders, and more particularly to a method for determining a triboelectric charge train of toners and carriers used in electrophotographic developers.

[0002]

2. Description of the Related Art A triboelectrification train is judged by directly rubbing two kinds of materials and examining the charge polarity of each material. For example, when the materials A and B are rubbed together, and A is positively charged and B is negatively charged, A determines that the triboelectric charging train is on the + side with respect to B.

By the way, when trying to determine the triboelectrification sequence of toners used in electrophotographic developers, if the toners are different in color, a mixture of two toners is stirred and charged, and then the mixture is mixed. By applying a high voltage to the sandwiching electrodes between the parallel electrodes and electrically separating them, the charging polarity of the toner can be determined from the color of the toner attached to each electrode and the voltage polarity of the electrodes. This makes it possible to determine the triboelectric charge trains of toners of different colors.

[0004]

However, since the toners of the same color cannot be distinguished by the colors, it is impossible to determine the triboelectric charge train of the toners by the conventional method. As for the carrier, the color thereof is almost black and cannot be distinguished by color, and the triboelectrification series cannot be determined.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to provide a method for accurately determining the triboelectrification sequence of toner or carrier.

[0006]

The above object can be achieved by the following method.

(First Method) Mixing ratio T / C (first powder) of the second powder A and the powder B which are different from each other with respect to the common first powder (Weight of powder / weight of second powder) are mixed to prepare a mixture, and the charge amount Q / M of the first powder of each mixture is measured,
From the relationship between the charge amount Q / M and the mixing ratio T / C, the mixing ratio T /
The value of the charge amount Q / M when C is 0 is determined, and the triboelectrification sequence of the second powder of the mixture having the larger value is defined as the negative side, and the triboelectrification sequence of the second powder of the mixture having the smaller value is represented as the negative side. Determined as + side.

(Second Method) A mixture is prepared by mixing different first powder A and first powder B with a common second powder with different mixing ratios T / C. Then, the relationship between the mixing ratio T / C and the charge amount Q / M of the first powder is measured, and the measured value is applied to the following formula using the least square method or the like to obtain the value of Q / M (0). And Lch value, Q / M
The value of (0) ÷ Lch is calculated, and the triboelectrification series of the first powder of the mixture with the larger calculated value is the + side, and the triboelectrification series of the first powder of the mixture with the smaller value is the − side. To determine.

Q / M = (Q / M (0)) / (1 + Lch · (T / c)) (Equation 1)

[0010]

By the above means, the triboelectric charge train can be accurately determined. In particular, high-accuracy printing can be realized by clearly ascertaining the triboelectric charging series of toner used in the development of an electrophotographic apparatus.

[0011]

EXAMPLES It will be described that the determination method of the present invention can be used to accurately determine a triboelectrification series.

First, the charge amount Q / M and the toner mixing ratio T / C
It will be described from how the relationship of (weight of toner / weight of carrier) is determined, and that the frictional charge sequence can be determined from there will be described.

Consider a developer in which m1 (g) toner and m2 (g) carrier are mixed. The toner mixing ratio T / C is expressed by the equation 2.

[0014]

## EQU00002 ## T / C = m1 / m2 (Equation 2) A phenomenon in which the toner is charged by friction between the toner and the carrier will be described with reference to the model of FIG. The model of FIG. 1 is a charging model in which the amount of electrons that move during contact is determined by the work function difference between toner and carrier and the number of surface states. The work function is the minimum energy for releasing electrons into a vacuum, and is shown by W1 and W2 in FIG. The number of surface states indicates how many electrons are present in the unit energy width or there are places where the electrons can enter. In Fig. 1, N1 and N2
Indicated by. Triboelectric charging between toner and carrier is considered to be such that when the toner and carrier come into contact with each other, electrons move from a smaller work function to a larger work function, and the movement of electrons ends when the work function difference after movement becomes zero. There is. The idea is that the toner and carrier in FIG. 1 are each considered as a container containing water, and if the bottom of the container is connected by a pipe, the water moves from the higher water level to the lower water level, and both containers are It is very similar to the movement of water ending when the water levels match. The work function of water is the distance from the top of the container to the water.

When the work function of the carrier is smaller than that of the toner as shown in FIG. 1, electrons move from the carrier to the toner. The amount Q of electric charges to be moved can be calculated from the above-mentioned model and becomes as shown in Formula 3.

[0016]

(Equation 3)

Here, N1 and N2 are the surface state numbers of the toner and the carrier, W1 and W2 are the work functions of the toner and the carrier,
Further, e is the absolute value of the electronic charge. This formula is described on page 177 of "Baifukan," by AR Bryce, Akira Miyake and Wataru Segawa, jointly translated "Electrical Properties of Polymers".

Amount of charge Q / M per unit weight of toner
Is obtained by dividing Q by m1 and becomes as shown in Equation 4.

[0019]

[Equation 4]

Next, a relational expression with T / C will be derived. Assuming that the number of surface states per unit weight of toner and carrier is n1 and n2, the following relationships exist between the weights m1 and m2 and the number of surface states N1 and N2.

[0021]

[Equation 5] N1 = n1 × m1 (Equation 5)

[0022]

[Equation 6] N2 = n2 × m2 (Equation 6) From Equations 2, 5, and 6,

[0023]

[Equation 7] N1 / N2 = (n1 / n2) × T / C (Equation 7) Eliminating m1 from Equation 4 and using the relational expression of Equation 7,

[0024]

(Equation 8)

[0025] The numerator of Equation 8 is Q / M (0), and n1 / n2 of the numerator is Lch.

[0026]

[Equation 9] Q / M (0) = e × n1 (W2-W1) (Equation 9)

[0027]

[Equation 10] Lch = n1 / n2 (Equation 10) Then, Equation 8 becomes

[0028]

[Equation 11]

It becomes This is an equation representing the relationship between the toner charge amount Q / M and the toner mixture ratio T / C. From this equation 11, it is understood that Q / M (0) is the value of Q / M extrapolated to the toner mixing ratio T / C = 0.

With various combinations of toner and carrier,
Developers having different toner mixing ratios T / C were prepared, and the charge amount Q / M thereof was measured by a blow-off method or the like. The least squares method was applied to the measurement result to obtain Q / M (0) and Lch in Eq. 11, and as a result, the difference between the Q / M calculated in Eq. 11 and the measured value was within 10%. This is in good agreement when the measurement variation of Q / M is taken into consideration. Therefore, Q / M and T
It has been found that the relationship of / C is expressed by Equation 11.

As described above, the charge amount Q / M and the toner mixing ratio T / C
The explanation of how the relationship is determined is finished. Next, a method for determining the triboelectric charge train based on this equation was devised, which will be described.

First, the first method will be described.

Considering Equation 9, this expression is only affected by its work function W2 with respect to the carrier.
Therefore, consider Q / M (0) when carriers C1 and C2 having different work functions are mixed with the same toner.
Assuming that the work function of the carrier C1 is Wc1 and the work function of the carrier C2 is Wc2, the relationship between Q / M and T / C of the developer prepared by mixing the carrier and the toner is investigated, and the least squares method is applied or When Q / M (0) of the equation 11 is obtained by extrapolation from the measured value, it is expressed as follows. The work function of the toner is W1, and the number of surface states per unit weight is n1.

[0034]

[Equation 12] Q / M (0) c1 = e × n1 (Wc1-W1) (Equation 12)

[0035]

[Equation 13] Q / M (0) c2 = e × n1 (Wc2-W1) (Equation 13) When the difference between Equation 12 and Equation 13 is taken, it becomes as follows.

[0036]

[Equation 14] Q / M (0) c1−Q / M (0) c2 = e × n1 (Wc1−Wc2) (Equation 14) Looking at Equation 14, e is an absolute value of the electronic charge, and a positive value, Since n1 is also the number of surface states per unit weight of toner, it is a positive value. Therefore, the difference of Q / M (0) on the left side is carrier C
It can be seen that it is proportional to the difference between the work functions of 1 and C2.
The value of Q / M (0) on the left side is obtained by combining each carrier with a common toner, preparing developers with different toner mixing ratios T / C, and measuring the charge amount Q / M by the blow-off method or the like. The result obtained by applying the least squares method to the equation 11
It can be found by fitting it or extrapolating directly from the measured value. Therefore, Q / M on the left side of Equation 14
Since the magnitude relationship of (0) is known, the magnitude relationship of the work functions on the right side is also known. By the way, as described above, when two types of materials are frictionally charged, one having a small work function is positively charged and one having a large work function is negatively charged. Therefore, the triboelectrification train has a plus side when the work function is small, and the triboelectrification train is the minus side when the work function is large.

By the method described above, it is possible to determine the magnitude relationship of the work functions of carriers, that is, the triboelectric charge train.

Next, a method of determining the triboelectric charge train of toner will be described. This can be considered by switching the positions of the toner and the carrier by the method described above. That is, the charge amount considers the charge amount Q / Mc of the carrier, and the mixing ratio considers the carrier mixing ratio C / T. Then, as in the above method, Q / Mc extrapolated to the carrier mixing ratio C / T = 0.
Calculate (0). Consider a case where Toner 1 having a work function Wt1 and Toner 2 having a work function Wt2 are combined with a carrier having a work function W2 and the number of surface states per unit weight is n2. Similar to the above case,

[0039]

[Equation 15] Q / Mc (0) t1−Q / Mc (0) t2 = e × n2 (Wt1−Wt2) (Equation 15) Since the left side of Expression 15 can be obtained from the measured value, the magnitude relation of the work functions on the right side can be known, and the triboelectric charge train of toner can be determined. The carrier mixture ratio C / T = 0 corresponds to 100% in the toner mixture ratio T / C, that is, the toner concentration Tc representing the weight of the toner in the commonly used developer is infinite. Therefore,
In this method, the relationship between Q / M and Tc may be examined by actual measurement, and the value of the charge amount Q / Mc of the carrier when extrapolated to Tc = 100% may be obtained.

Next, the second method will be described.

By preparing developers having different toner mixture ratios T / C, measuring the charge amount Q / M, and applying the least squares method, it is possible to obtain Q / M (0) and Lch in Eq. Indicated.
Then it can be seen that the Q / M at any T / C can be calculated. Then, Lch of the denominator of equation 11
Q / M when × T / C is sufficiently larger than 1
When asked for

[0042]

[Equation 16]

It becomes From the relational expressions of Equations 9 and 10, Q / M
If (0) and Lch are returned to the original contents,

[0044]

[Equation 17]

It becomes A toner having a work function of WA and a toner B having a work function of WA have surface states n per unit weight.
When combined with a carrier with a work function of W2 in 2, the Q / M of each toner is

[0046]

(Equation 18)

[0047]

[Formula 19]

Is as follows. Taking the difference between Equation 18 and Equation 19,

[0049]

(Equation 20)

It becomes In the formula 20, the work function order is the formula 1.
Although it is the reverse of 4, it shows that the difference in Q / M is proportional to the difference in work function, as in the case of Equation 14. Also, this number 20 is

[0051]

[Equation 21] Q / MA (0) = e × nA (W2-WA) (Equation 21)

[0052]

[Equation 22] LchA = nA / n2 (Equation 22)

[0053]

[Equation 23] Q / MB (0) = e × nB (W2-WB) (Equation 23)

[0054]

[Equation 24] When rewritten using LchB = nB / n2 (Equation 24),

[0055]

(Equation 25)

It becomes Since T / C is a positive value in Equation 25, the difference in Q / M on the left side is proportional to the difference between the first and second terms in the numerator on the right side. Therefore, to determine the triboelectric charge train, attention should be paid to the value of Q / M ÷ Lch on the right side. Also, from equations 20 and 25,

[0057]

[Equation 26] Q / MA (0) ÷ LchA−Q / MB (0) ÷ LchB = e × n2 (WB−WA) (Equation 26) From this, it can be seen that the larger the value of Q / M ÷ Lch on the left side, the smaller the work function on the right side, and the triboelectrification train is on the + side. Similar to the first method, the size of the work function is known, so that the triboelectric charge train can be determined.

The actual measurement results of the present invention will be described below.

(First Embodiment) An example of determining the frictional charge train of the carrier will be described.

The toner and carrier used for the judgment are as follows.

Toner A Polyester resin, negatively charged, blue Carrier a Binder type, binder resin: polystyrene, acrylic coating Carrier b Binder type, binder resin: polystyrene, no coating treatment Carrier c Binder type, binder resin: polyester, no coating treatment Toner A and carriers a, b and c are respectively combined,
Developers having different toner mixing ratios were prepared, and the relationship between the charge amount Q / M and the toner mixing ratio T / C was investigated.

The results are shown in Table 1.

[0063]

[Table 1]

From Table 1, the values of Q / M (0) are, from the larger value, carrier c, carrier b, and carrier a. From the above description, the work function magnitude is larger. The order is carrier c, carrier b, carrier a. Therefore, the triboelectric charge train can be determined to be the carrier c, the carrier b, and the carrier a in order from the negative side. By the way, when the triboelectrification series of the surface materials of the carriers a, b, and c are examined in the Electrostatics Handbook (edited by the Institute of Electrostatics and the Society of Polymer Science), the order is from negative side to polyester, polystyrene, and acrylic. This is consistent with the determination result of this embodiment. Therefore, it was shown that the frictional charge train determination method of the present invention can determine the frictional charge train of the carrier.

(Second Embodiment) An embodiment for determining the triboelectric charge train of toner will be described.

The toner and carrier used for the judgment are as follows.

Toner A polyester resin, negatively charged, blue toner B polyester resin, negatively charged, black toner C polyester resin, negatively charged, red carrier a binder type, binder resin: polystyrene, acrylic coating toner A, B, C and carrier combining a,
Developers having different toner mixing ratios were prepared, and the relationship between the carrier charge amount Q / Mc and the carrier mixing ratio C / T was investigated.

The results are shown in Table 2. Toner A,
When B and C are combined with the carrier a, they are all negatively charged.

[0069]

[Table 2]

From Table 2, the values of Q / Mc (0) are the toner A, the toner B, and the toner C from the largest value.
From the above description, the magnitude of the work function is in the order of toner A, toner B, and toner C from the largest. Therefore, the triboelectric charge train can be determined as toner A, toner B, and toner C in order from the negative side. By the way, toner A, B,
Since C has a different color, it is possible to determine the triboelectrification series from the respective charging polarities by directly mixing the toners and triboelectrifying them. Therefore, the triboelectric charging series of the toners A, B, and C was determined by the following procedure.

(Procedure 1) In combination with carrier a, 2
A developer having an excessive toner concentration containing 12 parts by weight of each type of toner is prepared.

(Procedure 2) The developer 1 prepared in the procedure 1 is put between the upper electrode 2 and the lower electrode 3 of the apparatus shown in FIG. 2, and the developer 1 is disturbed by the magnetic stirrer 5 while the upper electrode 2 is being disturbed. 2 + voltage from + power source 6 or-voltage to-power source 7
To apply toner to the upper electrode 2. The upper electrode 2 and the lower electrode 3 are supported by an insulating material 4 with a predetermined gap.

(Procedure 3) In the triboelectric series, the color of the toner adhered to the upper electrode 2 is checked, and when the + voltage is applied to the upper electrode 2, the toner of the adhered color is the − side and the − voltage is applied to the upper electrode 2. It is possible to determine that the toner of the color adhered when is applied to the + side.

The reason why the carrier is used in the determination of the triboelectrification series is to improve the mixing property of the two types of toner. Further, the toners A, B, and C are all negatively charged with respect to the carrier used here, but since the toner density is excessive, the positively charged toner is not rubbed with the carrier but rubbed with the toner. It is thought to have occurred.

As a result of examining the charging polarities of the toners A, B, and C in the above procedure, it is found that the toner A is negatively charged with respect to the toner B and the toner B is negatively charged with respect to the toner C. It was Therefore, the triboelectric charging sequence is toner A, toner B, and toner C in order from the negative side. This is the same as the above determination result. Therefore, it was shown that the triboelectric charge series determination method of the present invention can determine the triboelectric charge series of toner.

(Embodiment 3) Another embodiment of determination of the triboelectric charge train of toner will be described.

The toner and carrier used for the determination are the same as those in the second embodiment. Apply the measurement result of the charge amount shown in Table 2 to Equation 1 to find Q / M (0) and Lch, and calculate Q / M
(0) shows the result of calculating Lch.

[0078]

[Table 3]

From Table 3, the values of Q / M (0) ÷ Lch are toner C, toner B, and toner A from the larger value. From the above description, the work function has the larger value. From toner A to toner B to toner C in this order. Therefore, the triboelectric charge train can be determined as toner A, toner B, and toner C in order from the negative side. By the way, Toner A,
The triboelectric charge trains of B and C are determined by directly mixing the toners in the second embodiment described above, and as a result, the toner A, the toner B, and the toner C are in order from the negative side. This is consistent with the determination result of this embodiment. Therefore, it was shown that the triboelectric charge series determination method of the present invention can determine the triboelectric charge series of toner.

[0080]

As described above, according to the present invention, it is possible to accurately determine the triboelectric charge train of the toner and the carrier. As a result, it is possible to determine the triboelectrification series of toners and carriers of the same color, which cannot be confirmed by the triboelectrification method. It should be noted that this is not limited to toner and carrier, but can be widely applied to powder.

[Brief description of drawings]

FIG. 1 is a model diagram of triboelectric charging.

FIG. 2 is a configuration diagram of an apparatus for confirming the charge polarity of toner.

[Explanation of symbols]

1 ... Developer, 2 ... upper electrode, 3 ... lower electrode, 4 ... insulating material, 5 ... magnetic stirrer, 6 ... + power supply, 7 ...- power supply.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G03G 9/08 9/10

Claims (2)

[Claims] 1. A mixing ratio T / T of a powder A and a powder B which are different from each other in a second powder with respect to a common first powder.
C (the weight of the first powder / the weight of the second powder) is mixed to prepare a mixture, and the charge amount Q / M of the first powder of each mixture is measured, and the charge is calculated. Quantity Q / M
And the mixing ratio T / C, the value of the charge amount Q / M when the mixing ratio T / C is 0 is obtained, and the triboelectrification series of the second powder of the mixture having the larger value is the negative side Second of the mixture of
The method for determining the frictional charge sequence of powder is characterized in that the frictional charge sequence of the powder is determined to be + side. 2. A common second powder A and powder B having different mixing ratios T / C (weight of the first powder / weight of the second powder). The mixture is mixed with the powder of No. 1, and the mixing ratio T / C and the charge amount of the first powder Q /
Measure the relationship with M, apply the measured value to Equation 1 using the method of least squares, etc., find the value of Q / M (0) and the value of Lch, and calculate the value of Q / M (0) ÷ Lch Is calculated, and the triboelectrification series of the first powder of the mixture having the larger calculated value is set to the + side,
A method for determining a triboelectrification series of powders, characterized in that the triboelectrification series of the first powder of the smaller mixture is judged to be the-side. [Equation 1]