JPH11245246A - Composite of resin and filler, and thermal head support using the composite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a deformation at a high temperature from occurring by compounding a thermoset resin and a filler at a specific ratio and manufacturing a composite of the resin and the filler which has a specific load deflection temperature and an even face whose degree of evenness is below a specific level after adding a cold/hot cycle from a room temperature to a specific temperature. SOLUTION: A thermal head support 1 is composed of a composite of a thermoset resin and a filler having 30-60 vol.% ratio of the resin and 70-40 vol.% ratio of the filler. In this case, the composite of the resin and the filler shows 160 deg.C or higher load deflection temperature and has an even face 2a whose degree of evenness is 30 μm or less after adding a cold/hot cycle from a room temperature to 150 deg.C. The mixed raw material of the thermoset resin and the filler is molded under pressure at the room temperature, than the molding is peeled from a die and is thermally set into the composite. Thus the composite can be maintained at a high temperature without being deformed, so that it is applied to various uses in a good condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite of a resin and a filler having excellent heat resistance and a thermal head support using the same, and particularly to various recording devices such as a thermal card, a plastic card and a rewritable card. The present invention relates to a support for a thermal head which is preferably used as a means for thermal printing and thermal erasing on a material having good flatness.

[0002]

2. Description of the Related Art In recent years, various types of recording apparatus have been required to be reduced in size, price, power consumption, and printing accuracy.
For this reason, a low-cost, high-efficiency, and high-precision thermal head is desired.

The schematic structure of this thermal head is such that a head body 1 is mounted on a flat surface 2a of a support 2 as shown in FIG. The head body 1 has heating resistor elements arranged in a line on an insulating substrate.

[0004] In such a thermal head, the support 2 which greatly affects the characteristics can be obtained by die-casting a metal material such as aluminum, or
A resin obtained by injection molding of a heat-resistant resin such as polycarbonate, polyphenylene sulfide, polyether ether ketone, and acrylic resin is used.

[0005] In thermal printing or thermal erasing of materials requiring security, such as point cards, credit cards, and ID cards, the operating temperature of the thermal head tends to increase. At this time, when the support 2 is made of aluminum, the heat conductivity is as high as 237 W / m · K, so that the heat generated from the heating resistor array formed in a line on the insulating substrate forming the head body 1 is generated. It was easy to dissipate heat through support 2. Therefore, the ratio of the power applied to the heating resistor of the head body 1 to the thermal printing is low,
There was a problem that thermal efficiency was poor.

Therefore, in order to further improve the thermal efficiency, the support 2 of the thermal head is changed from a metal material such as aluminum to a heat-resistant resin material having a lower thermal conductivity. The ratio of the heat radiated through the fin can be remarkably reduced, and the heat efficiency can be remarkably improved.

However, when the support 2 is formed of a heat-resistant resin material, there is a problem that the flat surface 2a of the support 2 is easily deformed by the addition of a cooling / heating cycle. Especially,
In thermal printing and thermal erasure on hard materials such as thermal cards, plastic cards, and rewrite cards, the flatness of the printed material is very good. Therefore, when the support 2 is warped, the accuracy of thermal printing and thermal erasure decreases. There was a problem.

Therefore, by adding and mixing a filler to the heat-resistant resin, mechanical strength, heat resistance,
It has been proposed to obtain a resin composite having improved flatness stability after adding a thermal cycle (see Japanese Patent Application Laid-Open No. 4-353471).

[0009]

However, in such a resin composite, if a large amount of filler is added and mixed, there is a problem that not only the cost is increased but also the moldability is deteriorated.

That is, in the injection molding method and the transfer molding method, which are general methods for molding such a resin composite, when the filler compounding ratio is increased, the viscosity of the molten resin increases, resulting in poor flowability and gold. This makes it difficult to uniformly fill the mold, resulting in poor dimensional accuracy, cracks, warpage, and other defects.

Therefore, in order to form by injection molding or transfer molding, the filler content has to be reduced to about 20 to 30% by volume at present. for that reason,
Heat resistance, flatness stability due to the addition of a cooling / heating cycle, and the like could not be significantly improved as compared with ordinary resin materials.

However, there is an increasing demand for miniaturization, low cost, low power consumption, and high precision of printing of the various recording devices such as the printers described above. Regarding the heat resistance of the resin constituting No. 2 and the flatness stability due to the addition of a cooling / heating cycle, it has not been possible to sufficiently meet the requirements, and at present, it is strongly desired to improve the characteristics.

[0013]

Accordingly, the present invention provides a method for molding the above-mentioned resin composite, in which powder compression molding is carried out at room temperature, the mold is released from the mold, and the mixture is cured by heating. It has been found that the moldability can be improved even when the content is increased. The composite of a resin and a filler produced by the above-described method using ceramic powder as the filler can improve heat resistance and can also improve the flatness stability after the addition of a cooling / heating cycle, thereby forming the present invention.

That is, the present invention relates to a cooling / heating cycle comprising a thermosetting resin of 30 to 60% by volume and a filler of 70 to 40% by volume, a deflection temperature under load of 160 ° C. or more, and a room temperature to 150 ° C. It is characterized by a composite of a resin and a filler having a flat surface having a flatness of 30 μm or less after addition.

[0015] The present invention also provides a method of producing a composite of the above resin and filler by a step of pressing the mixed material of the thermosetting resin and the filler at room temperature, releasing the mixture from a mold, and heating and curing. It is characterized by doing.

According to the production method of the present invention, the moldability can be improved even if the content of the filler is as large as 70 to 40% by volume. Thus, a composite of a resin and a filler having excellent flatness and a flatness stability of 30 μm or less after the addition of a thermal cycle from room temperature to 150 ° C. is obtained.

As used herein, the term "load deflection temperature" refers to a temperature at which deformation occurs when a temperature is increased while applying a load to a resin-filler composite having a predetermined shape. When the deflection temperature under load is 160 ° C. or higher, the film can be suitably used as a support for a thermal head.

The flatness after the addition of the cooling / heating cycle refers to the flatness after adding the cooling / heating cycle from room temperature to 150 ° C. to the composite of resin and filler having a predetermined flat surface, as described in detail later. This refers to the flatness of the flat surface. If the flatness can be maintained at 30 μm or less, it can be suitably used as a thermal head support.

In the present invention, the ratio of the thermosetting resin is 30.
The reason why it is set to ~ 60% by volume is that if it is less than 30% by volume, the effect of improving heat resistance is poor and powder pressure molding becomes difficult. This is because the dimensional accuracy cannot be increased, and the heat resistance decreases.

As the thermosetting resin, epoxy type,
Various materials such as phenol-based, melamine-based, and polyester-based can be used, but a phenol-based resin is most suitable. As the filler, alumina (Al
₂ O ₃ ), silica (SiO ₂ ), steatite (MgO
O _2), forsterite (2MgO · SiO _2), mullite _{(3Al 2 O 3 · 2SiO 2} ), cordierite _{(3MgO · 2Al 2 O 3 ·} 5Si
One or more ceramics such as O ₂ ) are used, and the average particle size is 20 μm or less.

The average particle diameter of the filler is determined by analyzing an arbitrary surface or cross section of the composite of the resin and the filler with an image analyzer and calculating the average value of the equivalent circle diameter of the filler particles present on this surface. Can be measured by

When the particle size of the filler is reduced as described above, the dispersibility may be deteriorated when mixed with the resin. In this case, the surface of the powder constituting the filler is coated with a coupling agent. It is good.

In the composite of the resin and the filler of the present invention, by increasing the content of the filler, the flatness stability after the addition of the thermal cycle can be improved.

In addition, in addition to the thermosetting resin and the filler, known fillers such as clay, talc, mica, kaolin, silica sand, calcium carbonate, and the like are appropriately added to the composite of the resin and the filler as a bulking agent. It doesn't hurt anything. In addition, if necessary, a known curing agent, a curing aid, a lubricant, a plasticizer, a dispersant, a coloring agent, a release agent, or other known additives may be added in a small amount to such an extent that there is no practical problem. No problem. However, the content of carbon (C) generally used as a colorant is preferably 0.5% by weight or less, more preferably 0.2% by weight or less.

Furthermore, Cl, P, Na, Al, Si, Sr, Mg, Zr, F
e, Co, Cu, Ta and the like may be contained, and even if these are mixed in about 0.1% by weight in the total amount, there is no problem in characteristics. In addition, a minute amount of another metal element or the like may be mixed for convenience in the manufacturing process.

In the present invention, the method of blending various raw materials is not particularly limited, and a known method can be employed. For example, a method in which a compound such as a filler is mixed with a thermosetting resin by a mixer, kneaded by a Brabender, and then pulverized. Alternatively, after melt-kneading the compound with a heating roll,
Examples of the method include pulverization. If necessary, the particles may be granulated to have a predetermined particle size and used for molding.

In the heat curing step, the mold is released from the mold, and the heat treatment is carried out at a temperature in the range of 80 to 250 ° C. in accordance with the properties of the thermosetting resin and the amount of the filler. In the case of heat treatment, a mold jig may be used in some cases.

Further, the present invention is characterized in that a thermal head support is constituted by using the flat surface provided on the above-mentioned composite of resin and filler as a mounting surface of the head body.

That is, by forming the thermal head support using a composite of a resin and a filler having high flatness stability after the application of the deflection temperature under load and the thermal cycle as described above, the thermal head support is maintained without being deformed even at a high temperature. Therefore, it is possible to obtain a thermal head support that can be favorably used in various applications.

[0030]

Embodiment 1 Hereinafter, an embodiment of the present invention will be described.

A phenol resin was used as the thermosetting resin, and alumina (Al ₂ O ₃ ) ceramic was used as the filler. Raw materials were prepared by varying the mixing ratio of phenol resin and alumina and the average particle size of alumina as shown in Table 1. Using each raw material, after pressure molding at room temperature, 80 ~
It was cured by heating at 250 ° C. to produce a test piece.

Table 1 shows the results of measuring the deflection temperature under load of the obtained test pieces. The measurement method is JIS K 72
Performed in the method of 07.

Specifically, for example, as shown in FIG.
Using a T (HEAT DISTORTION TEMPERATURE) testing machine, a 6.4 x 12.7 x 110 mm test piece 3 is supported at a span of 100 mm in a heat transfer medium, and a load rod 4 and a weight 5 are applied to the center at a stress of 18.5 k.
While applying a load of gf / cm ² or 4.6 kgf / cm ² , the temperature of the heat transfer medium is increased at 2 ° C./min, and the temperature when the deflection of the test piece 3 reaches 0.25 mm by the wire gauge 6 is measured. It can be determined by measuring with a total of 7.

According to Table 1, the content of the phenol resin is
When the content is 20% by volume or less, the shape of the molded body after the pressure molding at room temperature cannot be maintained. On the other hand, when the content is 80% by volume or more, the shape cannot be maintained during heat curing, so that it is not practical.

On the other hand, when the content of the phenol resin is 30
It can be seen that when the content is within the range of 6060% by volume, all exhibit a high load deflection temperature of 160 ° C. or more. The deflection temperature under load is improved as the content of the phenol resin is reduced and the content of the alumina is increased. Since the deflection temperature under load of the phenol resin itself is generally 160 ° C., it can be seen that the deflection temperature under load can be greatly improved by adding alumina powder.

The average particle size of alumina is not directly related to the deflection temperature under load. However, if the average particle size exceeds 20 μm, the surface roughness of the resin composite becomes rough, which is not practical. preferable.

[0037]

[Table 1]

Next, the same experiment was carried out for various combinations of resins and fillers. Table 2 shows phenolic resin-silica (SiO ₂ ), Table 3 shows phenolic resin-steatite (MgO.SiO ₂ ), Table 4 shows unsaturated polyester resin-alumina (Al ₂ O ₃ ), and epoxy resin-
Table 5 shows the silica (SiO ₂ ).

In any of the combinations of materials, the thermosetting resin was set at 30 to 60% by volume and the ceramics at 70 to 40% by volume could have a deflection temperature under load of 160 ° C. or higher.

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

[Table 5]

Example 2 Next, phenol resin was used as the thermosetting resin, alumina (Al ₂ O ₃ ) ceramics was used as the filler, and the raw material powders were mixed in various proportions as shown in Table 6. The mixture was weighed and mixed, and then the mixture was subjected to powder pressure molding at room temperature and heat-cured by heat treatment at 80 to 250 ° C to obtain a test piece of a composite of resin and filler. The test piece is 6 × 8 × 50, assuming the support 2 shown in FIG.
mm, and a flat surface 2a on which the head body 1 is placed is formed.

With respect to the test piece thus obtained, the flatness of the flat surface 2a after the addition of the thermal cycle was measured as follows. Specifically, the temperature is raised from room temperature to 150 ° C. in 20 minutes,
A cooling / heating cycle in which the furnace was cooled to room temperature after holding for 12 hours was added to the test piece, and the flatness of the mounting surface 2a was measured at room temperature after the initial value, after one cycle, and after two cycles. Note that the flatness was defined as the WCM (wave undulation measurement) of the measurement surface.

The results are shown in Table 6. According to Table 6, in the comparative examples (Nos. 5 and 6) consisting of only the resin, the flatness after the addition of the thermal cycle exceeded 30 μm, and the stability of the flatness was poor. In No.4, phenol resin is 65%
Therefore, the flatness after adding the thermal cycle exceeded 30 μm, and the stability of the flatness was poor.

On the other hand, those within the scope of the present invention (N
In o.1 to 3), it can be seen that the flatness after the cooling / heating cycle is 30 μm or less, which is excellent in flatness stability. Therefore, if the support 2 of the thermal head is formed using a composite of a resin and a filler within the scope of the present invention, the flatness of the flat surface 2a during repeated use is not deteriorated, and high-precision printing is performed. be able to.

[0048]

[Table 6]

[0049]

As described above, according to the present invention, it comprises 30 to 60% by volume of a thermosetting resin and 70 to 40% by volume of a filler, has a deflection temperature under load of 160 ° C. or more, and is heated from room temperature.
By forming a composite of a resin and a filler having a flat surface having a flatness of 30 μm or less after the addition of a cooling / heating cycle at 150 ° C., it can be used in various applications because it has little deformation at high temperatures.

In particular, if a thermal head support is formed of a composite of the above resin and filler, and the thermal head main body is mounted and fixed thereon, the support has excellent heat resistance and flatness stability. High-precision printing is possible, and in addition to that, the thermal conductivity is lower than that of metal, so that the thermal efficiency can be remarkably improved. Further, the thermal head can be significantly reduced in weight as compared with the case where a metal material is used.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic structure of a thermal head using a composite of a resin and a filler of the present invention.

FIG. 2 is a diagram for explaining a method of measuring a deflection temperature under load of a composite of a resin and a filler.

[Explanation of symbols]

 1: Head body 2: Support 3: Test piece 4: Load bar 5: Weight 6: Wire gauge 7: Thermometer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 67/06 C08L 101/00 101/00 C08J 5/10 CEZ // C08J 5/10 CEZ B41J 3/20 109C B29K 103: 00 B29L 31:00

Claims (3)

[Claims] 1. A flatness comprising a thermosetting resin of 30 to 60% by volume and a filler of 70 to 40% by volume, a deflection temperature under load of 160.degree. C. or more, and a room temperature to 150.degree. Having a flat surface of 30 μm or less. 2. The resin according to claim 1, wherein the mixed raw material of the thermosetting resin and the filler is molded at a normal temperature under pressure, then released from a mold and heated and cured. And filler complex. 3. A thermal head support comprising the composite of the resin and the filler according to claim 1 or 2, wherein the flat surface serves as a mounting surface of a head main body.