JP5168407B2 - Charged powder - Google Patents

Description

  The present invention relates to a chargeable powder, and more particularly to a chargeable powder used for forming a conductor pattern on a substrate by electrophotography.

For example, an automobile window (mainly a rear window) is usually provided with a conductive wire (anti-fogging heater wire) in which a conductive paste is baked in a line for the purpose of preventing fogging (anti-fogging). .
This anti-fogging heater wire generates heat when energized, and functions to remove fog caused by condensation by warming the glass (window). Therefore, the antifogging heater wire (conductive wire) needs to have an appropriate resistance value for heat generation.

  Therefore, in order to adjust the resistance value of the antifogging heater wire (conductive wire), it is generally known to add NiO to the conductive paste used for forming the conductive wire.

  Further, the antifogging heater wire (conductive wire) is required to have a dark color for the reason of making the antifogging heater wire (conductive wire) as inconspicuous as possible when viewed from the outside of the vehicle. As a means for improving the darkness, it is known to add a silicide compound to a conductive paste.

  Further, as a printing means for these conductive pastes, a screen printing method is mainly used. However, in the case of the screen printing method, it is necessary to produce a screen printing plate having a predetermined pattern for each vehicle type or glass type, and there is a problem that the production efficiency is low and the cost is increased.

  Therefore, in recent years, printing by electrophotography using a charged powder (toner) that does not require the preparation of a printing plate for each vehicle type or glass type has been studied.

  As the chargeable powder (toner) used in this electrophotographic method, toner mother particles containing conductive fine particles, a heat decomposable binder resin and glass frit, and heat decomposable organic resin fine particles attached to the surface of the toner mother particles Proposed chargeable powder (toner) for electronic printing, which has the requirement that the thermal decomposition temperature of the organic resin in the thermally decomposable organic resin fine particles is lower than the thermal decomposition temperature of the thermally decomposable binder resin (See Patent Document 1).

  The toner structure is shown in FIG. 5, for example. That is, the toner 60 has a thermal decomposition temperature on the surface of the toner base particles 54 including the conductive fine particles (metal particles) 51, the glass frit 52, and the thermally decomposable binder resin 53. It has a structure coated with thermally decomposable organic resin fine particles 55 lower than the thermal decomposition temperature.

  Furthermore, Patent Document 1 states that T100 of the thermally decomposable binder resin is 425 to 450 ° C., and that T100 of the organic resin in the thermally decomposable organic resin fine particles is desirably 250 to 420 ° C. (however, , T100 is the temperature at which the weight change disappeared when the temperature was raised from room temperature at a heating rate of 10 ° C./min using a thermogravimetric analyzer (TG)).

  In addition, the toner base particles constituting the toner are a method in which a thermally decomposable binder resin, metal particles, glass frit, etc. are mixed, kneaded and cooled to produce pellets, and then pulverized and classified (mixed pulverization method). It is said that the thermally decomposable organic resin fine particles can be attached to the thermally decomposable organic resin fine particles by using a mixer such as a particle compounding device, a Henschel mixer, and a pass mixer, for example ( Patent Document 1 paragraph 0063, etc.).

  Then, by using this toner, a linear pattern is formed on a glass substrate (such as an automobile window) by electrophotography, and the resin component is decomposed by heat treatment to sinter the metal particles. A conductive wire serving as a linear portion is formed.

That is, by using the toner of this Patent Document 1,
(a) It is possible to form a predetermined conductor pattern using electrophotography, eliminating the need to prepare a screen plate for each pattern.
(b) A conductor pattern having excellent adhesion to the glass plate surface can be formed. In particular, according to this toner, a conductor having a high transfer rate and excellent electrical characteristics (specific resistance value). A pattern can be formed, and a conductor pattern having desired characteristics can be easily formed.
It is said that effects such as can be obtained.

  By the way, it is desirable that the toner used for forming the antifogging heater wire disposed on the window of the automobile can form a conductive wire having a specific resistance as low as possible. Conductive wires need to have a certain resistance to generate heat, but the resistance can be controlled by additives, etc., and if trying to secure a wide controllable range, the toner has a resistance value that is as low as possible. It is desirable to have However, the actual situation is that Patent Document 1 does not show specific means for sufficiently reducing the resistance.

Further, in order to give the toner sufficient printability (chargeability), it is necessary to contain a large amount of resin. On the other hand, the metal particles contained in the toner are required to form a dense sintered film having a low specific resistance after firing, but in the case of a toner containing a large amount of resin, the resin and its decomposition gas are used to burn the metal particles. It tends to be a hindrance to tie When the sintering of the metal particles is hindered by the resin and the decomposition gas, the sintered film has a large number of voids, resulting in a decrease in conductivity as well as a decrease in the degree of adhesion with the substrate. However, Patent Document 1 does not disclose a configuration for decomposing and releasing a resin contained in a large amount in the toner without disturbing the sintering of the metal particles. In Examples of Patent Document 1, acid-modified polypropylene is used alone, and the conductive pattern (conductive wire) formed under these conditions is considered to have many pores and high specific resistance.
Therefore, when the toner of Patent Document 1 is used, it is considered difficult to form a conductive pattern that has a sufficiently low resistance, is dense, and has excellent adhesion to a glass substrate.

JP 2007-20677 A

  The present invention solves the above-described problems, and is a charge that can form a highly reliable conductive pattern that has low specific resistance, is dense, has high adhesion strength to a glass substrate, and does not peel or swell. An object is to provide a functional powder.

In order to solve the above problems, the charged powder of the present invention is
A charged powder for forming a conductive pattern on a glass substrate by electrophotography,
It includes metal particles, glass frit, acid-modified polyolefin resin, and acid-modified polyester resin.

  Examples of the acid modifier of the acid-modified polyolefin resin and the acid-modified polyester resin include unsaturated carboxylic acid or unsaturated polycarboxylic acid anhydride. In particular, unsaturated dicarboxylic acid and unsaturated dicarboxylic acid anhydride are preferable. Specific examples include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, maleic anhydride, itaconic anhydride, citraconic anhydride, and the like.

Examples of the main monomer constituting the acid-modified polyester resin include (meth) acrylate monomers such as acrylic acid esters and methacrylic acid esters, and unsaturated alcohol ester monomers such as vinyl acetate.
The acid-modified polyolefin resin is preferably one obtained by reacting a polymer composed of olefins such as ethylene, propylene, butadiene and isoprene, or a copolymer obtained by combining them with the acid modifier. In particular, polypropylene is preferable because a stable charge amount can be secured.

  In the chargeable powder of the present invention, the mixing ratio of the acid-modified polyolefin resin and the acid-modified polyester resin is a volume ratio in the range of acid-modified polyolefin resin: acid-modified polyester resin = 5: 95 to 25:75. It is desirable.

  The charged powder of the present invention is desirably used for forming a conductive pattern on a glass substrate.

  In addition, the chargeable powder of the present invention is desirably used for forming an antifogging heater wire for an automobile window.

  The chargeable powder of the present invention contains metal particles, glass frit, acid-modified polyolefin resin, and acid-modified polyester resin. By using this chargeable powder, the specific resistance is low, dense and It is possible to form a highly reliable conductive line without peeling or swelling.

If an acid-modified polyester resin is used as the resin for the chargeable powder (toner), a dense sintered film having a low specific resistance is formed. However, since the sintering proceeds before the decomposition gas escapes, the internal pressure increases and the film peels off. Frequent swelling occurs.
On the other hand, when the acid-modified polyolefin resin is used, the film thickness decreases due to rapid resin decomposition, so the metal particles must be rearranged to be densified accordingly. As a result, a dense sintered film is not formed. However, when an acid-modified polyolefin resin is used, since the decomposition gas easily escapes, peeling or swelling of the film does not occur.

  Therefore, as in the present invention, an acid-modified polyester resin and an acid-modified polyolefin resin are mixed at a predetermined ratio, and this is used as a resin for a chargeable powder. It becomes possible to obtain a sintered film without swelling.

  By using an acid-modified resin like the chargeable powder of the present invention, the metal particles can be dispersed in the resin without aggregation.

  The acid-modified resin is a resin having an acidic group such as a hydroxyl group or a carboxyl group in the side chain of a polyolefin resin or a polyester resin, and these acidic groups are electrostatically interacted with the base on the surface of the metal particles. By acting, the wettability of the resin to the metal particle surface is improved.

  In the chargeable powder of the present invention, the mixing ratio of the acid-modified polyolefin resin and the acid-modified polyester resin is in a volume ratio of acid-modified polyolefin resin: acid-modified polyester resin = 5: 95 to 25:75. Thus, it is possible to reliably obtain a chargeable powder capable of expressing a lower specific resistance value than the conventional chargeable powder. Moreover, it is desirable that the ratio of the resin (total of acid-modified polyolefin resin and acid-modified polyester resin) in the chargeable powder is 50 to 90 vol%. By setting it as such a ratio, printability (chargeability) and sinterability can be improved more.

The average particle size of the charged particles of the present invention is desirably in the range of 10 to 40 μm. Charged particles having an average particle size of less than 10 μm are randomly deposited on the photoconductor and difficult to remove regardless of the electrostatic latent image formed on the photoconductor in the printing press. descend. Conversely, if the average particle size is too large, the resolution of the image will be low, and if the average particle size exceeds 40 μm, the resolution necessary for drawing a desired conductive pattern cannot be obtained.
The average particle size of the metal particles used in the present invention is preferably 0.5 to 2 μm. When the average particle size is less than 0.5 μm, the sintering start temperature of the metal particles is lowered, so that the metal particles may start to be sintered in a state where the resin cannot be sufficiently removed. When the average particle diameter exceeds 2 μm, the metal particles easily fall off from the charged particles. Further, since the packing density is low, voids are easily formed between the particles during sintering, the sintering density is lowered, and as a result, the specific resistance is increased.

  When the charged powder of the present invention is used to form a conductive pattern on a glass substrate, the specific resistance is low, the adhesion strength to the glass substrate is excellent, and it is dense and reliable without peeling or swelling. It is possible to form a highly conductive pattern.

  Therefore, the chargeable powder of the present invention can be suitably used to form an antifogging heater wire for automobile windows.

It is sectional drawing which shows the structure of the chargeable powder concerning one Example (Example 1) of this invention. It is a diagram which shows the relationship between the specific resistance of the electroconductive pattern formed using the charged powder concerning Example 1 of this invention, and the ratio of the acid-modified polypropylene resin in resin which comprises a charged powder. It is a figure which shows the optical photograph of the sample (electroconductive pattern) formed using the chargeable powder concerning Example 1 of this invention, (a) is the ratio of acid-modified polypropylene resin in resin which comprises chargeable powder Is an optical photograph of a sample using 0 vol%, (b) is 12.5 vol%, and (c) is 100 vol% charged powder. It is a figure which shows typically the structure of the antifogging heater for motor vehicle windows formed through the process of printing and baking the chargeable powder of this invention. It is sectional drawing which shows the structure of the conventional chargeable toner.

  Examples of the present invention will be described below to describe the features of the present invention in more detail.

  FIG. 1 is a cross-sectional view showing a configuration of a chargeable powder (toner) according to an embodiment of the present invention, which is used when a conductor pattern is printed on a glass substrate by electrophotography. It is.

[Composition of charged powder]
As shown in FIG. 1, the conductive powder 10 for forming a conductor pattern comprises metal particles (silver particles) 1, glass frit (glass powder) 2, acid-modified polyolefin resin and acid-modified polyester resin. And a mixed thermoplastic resin 3 blended in proportions.

  In this embodiment, silver particles having an average particle diameter of 1.0 μm are used as the metal particles (silver particles) 1.

  As the glass frit 2, a B—Si—O glass frit having a softening temperature of 500 ° C. is used.

As the acid-modified polyolefin resin, an acid-modified polypropylene resin having an acid value of 52 mgKOH / g is used.
As the acid-modified polyester resin, an acid-modified polyester resin having an acid value of 12 mgKOH / g is used.

  As described above, the chargeable powder 10 of this embodiment is obtained by dispersing the silver particles 1 and the glass frit (glass powder) 2 in the mixed thermoplastic resin 3, and the chargeable powder of this embodiment. Has an average particle size of 20 μm.

[Method for producing charged powder]
Next, the manufacturing method of this chargeable powder is demonstrated.
(1) Umex1010 (acid value 52 mgKOH / g) manufactured by Sanyo Chemical Industries was prepared as an acid-modified polypropylene resin.
Moreover, ER-502 (acid value 12 mgKOH / g) manufactured by Mitsubishi Rayon was prepared as an acid-modified polyester resin.
Further, silver particles having an average particle diameter of 1.0 μm were prepared as silver particles.
Furthermore, a B—Si—O-based glass frit having a softening temperature of 500 ° C. was prepared as a glass frit (glass powder).

  (2) Each of the above raw materials was weighed out and mixed so as to have the ratio shown in Table 1, and then kneaded in a small twin-screw extruder. The kneading was performed at 120 ° C. and 300 rpm.

  (3) Then, the obtained kneaded product was finely pulverized with a jet mill and classified to obtain a charged powder (toner) having an average particle diameter of 20 μm.

[Formation of conductive pattern]
The charged powder (toner) produced as described above was printed on a glass substrate with a size of 50 mm × 3 mm and a thickness of 50 μm.
Then, this glass substrate was baked under conditions of 600 ° C. for 5 minutes, and a sample in which a conductive pattern was formed on the surface of the glass substrate was produced.
And the specific resistance of the obtained sample was measured using the four probe method.
The results are shown in Table 1 and FIG.

The sample was observed and photographed with an optical microscope. The obtained optical photograph is shown in FIG.
Moreover, the cross section of the conductive pattern formed on the glass substrate was observed, and the presence / absence of peeling and the occurrence of pores were examined. The results are also shown in Table 1.

  As shown in Table 1, in the case of the sample of sample number 1 in which the acid-modified polyester resin is 100% (that is, the acid-modified polypropylene resin is 0%), the specific resistance value is as low as 3.1 μΩ · cm, but the glass substrate is used. The film (conductive pattern) had low adhesion, and as can be seen from FIG. 3A, foam-like peeling was observed.

  Further, in the case of the sample No. 7 in which the acid-modified polyester resin is 0% (that is, the acid-modified polypropylene resin is 100%), it is not known from FIG. 3C, but as a result of observing the cross section, there are many pores. It was confirmed that the density was low.

  On the other hand, in the case of samples Nos. 2 to 6 (samples in which a conductive pattern is formed using a charged powder containing both acid-modified polyester resin and acid-modified polypropylene resin), peeling from the glass substrate is also recognized. It was confirmed that a highly dense conductive pattern was obtained. In Table 1, a circle is shown in the column of the observation result of the conductive pattern.

  In addition, in the case of the sample of sample number 3 where the ratio of the acid-modified polypropylene resin is 12.5 vol%, as shown in FIG. 3B, the formed conductive pattern is in a dense and uniform state as a whole. As a result of observing the cross section, it was confirmed that the pores were hardly contained and the denseness was high.

  Therefore, it can be seen that in order to obtain a dense conductive pattern without peeling, it is necessary to use a charged powder containing at least both an acid-modified polypropylene resin and an acid-modified polyester resin.

  Next, regarding the samples of Sample Nos. 5 and 6 having a ratio of acid-modified polyester resin of 65 to 50%, it can be seen that a dense conductive pattern with high adhesion to the glass substrate and less pores can be obtained. . Further, it was confirmed that the specific resistance value was about 4 μΩ · cm, which was a practical level.

In addition, when the samples of Sample Nos. 2 to 4 in which the ratio of the acid-modified polyester resin is 95 to 75% are obtained, a dense conductive pattern with high adhesion to the glass substrate and less pores is obtained. It was confirmed that the resistance value was as extremely low as 3 μΩ · cm or less.
From the above results, it can be seen that the ratio of the acid-modified polyester resin in the resin is desirably in the range of 95 to 75% in order to reduce the specific resistance value.

[Formation of anti-fogging heater wire for automobile windows]
A sample (chargeable powder) of sample number 2 in Table 1 was printed on the surface of a glass plate 11 for a rear window of an automobile by electrophotography and then baked, as shown in FIG. An anti-fogging heater wire (conductive wire portion) 12 and a bus bar 13 were formed on the surface of the glass plate 11 for use, and an anti-fogging heater 20 for an automobile window was produced.

  As a result, it is confirmed that the anti-fogging heater 20 for an automobile window provided with the dense anti-fogging heater wire (conductive wire portion) 12 and the bus bar 13 having high adhesion to the glass plate 11 and few pores can be formed. It was done.

In the above embodiment, the resin mixed with the acid-modified polypropylene resin and the acid-modified polyester resin is used as the resin to be included in the chargeable powder. However, in some cases, another resin (third resin) is used. It can also be included.
Further, in the above embodiment, the case where an acid-modified polypropylene resin is used as the acid-modified polyolefin resin has been described. However, in the present invention, the acid-modified polyolefin resin is not limited to this, and other resins such as ethylene Further, it is possible to use a polymer composed of olefins such as propylene, butadiene and isoprene, or a copolymer obtained by combining these with acid modification.

  Moreover, in the said Example, although silver particle was used as a metal particle, other metal particles, such as a copper particle, and alloy particles, such as a silver-palladium particle, can also be used.

  Further, in the above examples, B-Si-O glass frit having a softening temperature of 500 ° C. was used as the glass powder (glass frit), but the glass frit is not limited to this, and charged powder is used. In consideration of the type of glass to be printed, it is possible to select and use an appropriate one from various glass frits.

  The present invention is not limited to the above-described embodiments in other respects. The type of the conductive pattern to be formed using the charged powder of the present invention and the charged powder of the present invention. Various applications and modifications can be made within the scope of the invention with respect to the specific shape and the like of the conductive pattern.

1 Metal particles (silver particles)
2 Glass frit (glass powder)
DESCRIPTION OF SYMBOLS 3 Mixed thermoplastic resin 10 Chargeable powder 11 Glass plate for rear windows 12 Conductive line 13 Bus bar 20 Antifogging heater

Claims (4)

A charged powder for forming a conductive pattern on a glass substrate by electrophotography,
A charged powder comprising metal particles, glass frit, acid-modified polyolefin resin, and acid-modified polyester resin. The mixing ratio of the acid-modified polyolefin resin and the acid-modified polyester resin is:
The chargeable powder according to claim 1, wherein the volume ratio of the acid-modified polyolefin resin: acid-modified polyester resin is in the range of 5:95 to 25:75.   The chargeable powder according to claim 1 or 2, which is used for forming a conductive pattern on a glass substrate.   The chargeable powder according to any one of claims 1 to 3, wherein the chargeable powder is used to form an antifogging heater wire for an automobile window.

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