JP2002052602A - Biodegradable conductive composite molded object and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biodegradable conductive composite molded object having biodegradability and capable of being used even in a baking process and usable as a carrier tape. SOLUTION: A crystalline biodegradable conductive composite sheet formed from at least three layers among which at least two layers have different constituent is molded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a biodegradable conductive composite molded article and a carrier tape.

[0002]

2. Description of the Related Art In recent years, with great progress in surface mounting technology, demand for high-performance and small-sized electronic components, particularly chip-type electronic components such as ICs, transistors and diodes, has been increasing. These chip-type electronic components are usually housed in a carrier tape or tray obtained by secondary molding of a plastic sheet by vacuum molding, air pressure molding, press molding or the like, and are transported and stored. When housed in the above carrier tape, it is sealed with a top tape as a lid material and supplied as a package.

Conventionally, as this carrier tape, a conductive sheet obtained by integrally laminating a styrene-based resin composition obtained by kneading a large amount of conductive filler on the front and back of a base material layer made of a styrene-based resin by co-extrusion, A conductive sheet formed by molding a vinyl chloride resin composition obtained by kneading a conductive filler such as carbon black into a resin into a sheet, or a sheet made of a thermoplastic resin such as a styrene resin or an ethylene terephthalate resin. A conductive sheet provided with a layer and subjected to secondary molding by press molding, vacuum molding or the like has been used.

[0004]

However, the carrier tape made of the above-mentioned conductive sheet is inferior in heat resistance, and is therefore used as a carrier tape for electronic parts requiring a baking step (heating to 100 ° C. or more). I didn't.

[0005] When such heat resistance is required,
Polycarbonate has been mainly used. However, since this has environmental problems, it is desired to have a carrier tape that has physical properties suitable as a carrier tape during use and that biodegrades in a short period of time in a natural environment after use.

Japanese Patent Application Laid-Open No. H10-120887 discloses that such a biodegradable resin is used as a carrier tape.
JP-A-10-120888 discloses a composition obtained by adding a crystalline SiO ₂ , a crystalline inorganic filler, and a conductive carbon to a polylactic acid-based or non-polylactic acid-based aliphatic polyester, in the range of 85 to 125. A molded product excellent in heat resistance by filling in a mold at a temperature of ° C. and crystallizing the same is disclosed. However, the above-mentioned molded article is mainly made of a conductive tray formed by injection molding, and cannot be applied to a laminate.

[0007] In addition to the above, Japanese Patent Application Laid-Open No. H11-399 discloses that a biodegradable resin is used as a carrier tape.
No. 45 discloses a polylactic acid-based resin and a polyalkylalkanoate-based resin in which an inorganic filler, a conductive filler, and the like are added. However, the biodegradable conductive carrier tape requires a large amount of conductive filler in order to obtain a desired surface resistance. For this reason, the fillers are liable to agglomerate to generate lumps, and there is a cost problem. Further, the inorganic filler is added in a large amount of 10 to 40 parts by weight for improving the conductivity, rigidity and biodegradability of the sheet and reducing the cost. Therefore, bumps are likely to occur on the surface of the obtained biodegradable conductive carrier tape.

Furthermore, Japanese Patent Application Laid-Open No. 2000-85837 discloses a carrier tape characterized by providing a coating layer containing a conductive material on a base layer made of a biodegradable resin. However, in this method, since only the surface layer has conductivity, the most important surface resistivity can be reduced, but the volume resistivity does not decrease in the thickness direction, and depending on the method of use, it is difficult to take the ground, There is a possibility that the entire inner surface of the carrier tape is charged and the chip-type electronic component is damaged.

Accordingly, an object of the present invention is to provide a conductive composite molded article which has biodegradability, can be used in a baking step, and can be used as a carrier tape.

[0010]

The present invention has solved the above-mentioned problems by forming a biodegradable conductive composite sheet formed of at least three layers immediately after crystallization.

[0011] Since the molded body of the crystallized biodegradable conductive composite sheet is used, it has heat resistance and can be used in a baking step.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The biodegradable conductive composite sheet according to the present invention is obtained by molding a biodegradable conductive composite sheet under predetermined conditions.

[0014] The biodegradable conductive composite sheet is a laminate formed of at least three layers. One or both outer layers of the laminate contain a polylactic acid-based polymer, talc, and a conductive agent. The inner layer of the laminate contains a polylactic acid-based polymer, talc, and, if necessary, a conductive agent. The outer layer and the inner layer have different components or component ratios, that is, different components. When the laminate has four or more layers, at least one of the two or more inner layers other than both outer layers may have the above-described components.

The above-mentioned polylactic acid-based polymer has a structural unit of L
-Poly (L-lactic acid) which is lactic acid, poly (D-lactic acid) whose structural unit is D-lactic acid, poly (DL-lactic acid) whose structural units are L-lactic acid and D-lactic acid, and a mixture thereof And further may be a copolymer with a hydroxycarboxylic acid unit described below.

As the polymerization method for the polylactic acid polymer, any known method such as a condensation polymerization method and a ring-opening polymerization method can be employed. For example, in the polycondensation method, L-lactic acid or D-lactic acid or a mixture thereof can be directly dehydrated and polycondensed to obtain a polylactic acid-based polymer having an arbitrary composition.

In the ring-opening polymerization method, lactide, which is a cyclic dimer of lactic acid, can be obtained by using a selected catalyst and a polylactic acid-based polymer while using a polymerization regulator and the like as necessary. it can. Lactide includes L-lactic acid dimer L-
Lactide, D-lactide which is a dimer of D-lactic acid, and DL-lactide further comprising L-lactic acid and D-lactic acid,
Polylactic acid having any composition and crystallinity can be obtained by mixing and polymerizing these as necessary.

Further, if necessary, non-aliphatic dicarboxylic acids such as terefulic acid and / or
Alternatively, a non-aliphatic diol such as an ethylene oxide adduct of bisphenol A may be used.

Further, a small amount of a chain extender, for example, a diisocyanate compound, an epoxy compound, an acid anhydride or the like can be used for the purpose of increasing the molecular weight. The preferred range of the weight average molecular weight of the polymer is from 60,000 to 1,000,000. When it is below this range, practical physical properties are hardly exhibited, and when it is above this, the melt viscosity is too high and the moldability may be poor.

The other hydroxycarboxylic acid units copolymerized with polylactic acid include optical isomers of lactic acid (D-lactic acid for L-lactic acid, L-lactic acid for D-lactic acid), glycol Acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid Such as bifunctional aliphatic hydroxycarboxylic acids and caprolactone,
Lactones such as butyrolactone and valerolactone are exemplified.

In addition to the polylactic acid, the outer layer and the inner layer may be, if necessary, polyhydroxycarboxylic acids other than polylactic acid, aliphatic polyesters obtained by condensing aliphatic diols and aliphatic dicarboxylic acids, and cyclic lactones. Aliphatic polyester obtained by ring-opening polymerization of a synthetic aliphatic polyester,
An aliphatic polyester biosynthesized in the cells may be added.

Examples of the polyhydroxycarboxylic acids other than the above-mentioned polylactic acid include 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, and 2-hydroxy-butyric acid.
Examples include homopolymers and copolymers of hydroxycarboxylic acids such as 3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-methyllactic acid, and 2-hydroxycaproic acid.

Examples of the aliphatic diol include ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like. In addition, typical examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, suberic acid, sebacic acid, and dodecane diacid. As the aliphatic polyester obtained by condensing these aliphatic diols and aliphatic dicarboxylic acids, one or more of each of the above compounds may be selected and subjected to condensation polymerization or, if necessary, jumping with an isocyanate compound or the like. Up to get the desired polymer.

The aliphatic polyester obtained by ring-opening polymerization of the above-mentioned cyclic lactones is obtained by polymerizing one or more kinds of cyclic monomers such as ε-caprolactone, δ-valerolactone, β-methyl-δ-valerolactone. It is manufactured by

Examples of the above-mentioned synthetic aliphatic polyester include cyclic anhydrides and oxiranes, such as copolymers of succinic anhydride with ethylene oxide and propion oxide.

As the aliphatic polyester biosynthesized in the above-mentioned cells, acetyl coenzyme A (acetyl-Co) is used in cells such as alkaligenes eutrophus.
Aliphatic polyesters biosynthesized according to A) are known. This aliphatic polyester is mainly poly-β-hydroxybutyric acid (poly 3HB), but in order to improve practical properties as a plastic, a hydroxy valeric acid unit (HV) is copolymerized to obtain poly (3HB-CO- (3HV) is industrially advantageous. The HV copolymerization ratio is generally from 0 to 40%. Further, a long-chain hydroxyalkanoate may be copolymerized.

The talc refers to a hydrated silicate mineral, and has a role as a crystal nucleus when crystallizing the polylactic acid-based polymer.

Examples of the conductive agent include conductive carbon, tin oxide, antimony oxide, and indium oxide. These may be used alone or in combination of two or more. Among these, conductive carbon is preferred from the viewpoint of moldability, resistivity after molding, and the like. Examples of the conductive carbon include Ketjen Black EC, furnace black, channel black, acetylene black, and the like.Ketjen Black EC is more preferred in that high conductivity can be obtained with a small amount of addition. preferable. When Ketjen Black EC is used, a small amount of Ketjen Black EC is used, so that the mechanical properties of the biodegradable conductive composite sheet are less likely to decrease.

The average particle size of the conductive agent is 0.01 to 1
0 μm is preferable, and 0.05 to 5 μm is particularly preferable.
If it is less than 0.01 μm, dispersion in the raw material resin is poor, and
If the thickness is more than 0 μm, the rigidity of the obtained biodegradable conductive composite sheet is increased, and the characteristics desired as a carrier tape are lost.

In the present invention, it is most important to make a laminate having a specific structure from these raw materials.

The average particle diameter D50 of talc in the outer layer and the inner layer is determined by a laser diffraction method.
It is preferably 3.0 μm or less. If it is larger than 3.0 μm, the effect of promoting crystallization is small. The amount of talc is preferably 0.3 to 15% by weight, and 0.3 to 10% by weight.
Is preferred. When the amount is less than 0.3% by weight, the effect of promoting crystallization is small, and when the amount is more than 15% by weight, dispersibility in the polylactic acid-based polymer is deteriorated, which may result in lumps.

The amount of the conductive agent in the outer layer is preferably set so that the surface resistivity of the biodegradable conductive composite sheet described later falls within a predetermined range. It is preferably from 3 to 15% by weight, more preferably from 3 to 10% by weight. When the amount is less than 3% by weight, the conductivity of the surface of the obtained biodegradable conductive composite sheet is not sufficient, and
If the content is more than 15% by weight, the cost of the obtained biodegradable conductive composite sheet increases, and the sheet tends to be brittle, and furthermore, it is easy to produce bumps.

The amount of the conductive agent in the inner layer may vary depending on the method of use, since the entire inner surface of the carrier tape, which is difficult to be grounded, may be charged and the chip-type electronic component may be damaged. It is preferable that the volume resistivity in the thickness direction of the sheet is within a predetermined range. Specifically, the content is preferably 3% by weight or less based on the entire inner layer,
3% by weight is preferred. If the amount is less than 0.1% by weight, the conductivity in the thickness direction of the biodegradable conductive sheet may not be sufficient. If the amount is more than 3% by weight, the generation of bumps and an increase in cost may be caused.

[0034] In addition to the above components, lubricants, plasticizers, various surfactants, dyes, pigments, other additives and polymers are added to the outer layer and the inner layer as long as the effects of the present invention are not impaired. You can also. Examples of the lubricant include behenic acid, stearic acid, pentaerythritol monoester, pentaerythritol diester, pentaerythritol tetrastearate, pentaerythritol-adipate-stearate complex ester, dipentaerythritol-adipate-stearate complex ester, diester Hentaerythritol hexostearate and the like. Examples of the plasticizer include dioctyl phthalate. Examples of the surfactant include acetylene glycol, acetylene alcohol, glycerin fatty acid ester, and polyglycerin aliphatic ester.

As a method for producing the biodegradable conductive composite sheet according to the present invention, a commonly used laminating method such as a coextrusion method or a heat compression method can be used. The coextrusion method is a method in which a plurality of extruders are connected to a single die in a feed block type or a multi-manifold type. Examples of the die include a T die, an I die, and a round die. The thickness of the sheet is practically 0.05
To 3 mm, more preferably 0.1 to 1 mm.

At this time, the end materials (ends, defective products, etc.) of the biodegradable conductive composite sheet generated at the time of production are used as the inner layers of the laminate and do not satisfy the above requirements for the inner layer. be able to. As a result, it becomes possible to add the conductive agent in the middle layer.

The above-mentioned thermocompression bonding method is a method of forming a laminate of a different kind of film on the surface of the unwound mixed film by using a roll or a press plate.

The surface resistivity of the biodegradable conductive composite sheet thus obtained is preferably in the range of 10 ³ to 10 ⁸ Ω. If the surface resistivity is less than 10 ³ Ω, the terminals of the electronic components may be conductive and short-circuited.
^If it exceeds ⁸ Ω, sufficient conductivity cannot be obtained, and static electricity is likely to be generated.

The volume resistivity of the obtained biodegradable conductive composite sheet may be in the range of 10 ⁸ to 10 ¹³ Ω. This is because the locally generated static electricity is first diffused widely along the surface, and as a result, it is not necessary to locally secure a large amount of conductivity in the thickness direction.
Therefore, conductivity as high as the surface is not required in the thickness direction. However, when the resistance exceeds 10 ¹³ Ω, static electricity is easily generated.

The biodegradable conductive composite sheet is molded immediately after crystallization to obtain a molded article, and the molded article can be given heat resistance. Examples of the crystallization method include a method of preheating the biodegradable conductive sheet. Thereby, crystals can be generated in the layers constituting the biodegradable conductive composite sheet.

The above preheating is preferably performed at a temperature of 120 ° C. to 160 ° C. within one minute, preferably within 30 seconds. Heating for more than one minute is not preferred because the preheating zone becomes longer and the equipment becomes larger. Heating within 1 minute is preferable because it can exhibit sufficient heat resistance and conductivity, particularly when used for manufacturing a carrier tape. On the other hand, if the temperature is lower than 120 ° C., the crystallization speed becomes slow. Therefore, the crystallization is not sufficiently performed within 1 minute, and the heat resistance is poor. On the other hand, when the temperature exceeds 160 ° C., crystallization may be promoted too much and molding may be difficult. Therefore, by performing crystallization treatment in advance under the above conditions, a biodegradable conductive composite molded article having excellent heat resistance can be obtained.

Immediately after the preheating, molding, specifically, thermoforming is preferred. This is because if the time until the thermoforming after the preheating becomes long, the molding may become impossible.

Examples of the thermoforming method include sheet forming methods such as vacuum forming, pressure forming, and press forming. Various molded articles can be obtained by these methods.

As the biodegradable conductive composite molded article,
For example, a carrier tape or the like can be given.

[0045]

The present invention is not limited by the following examples. The physical properties in the examples were measured and evaluated by the following methods.

The surface resistivity test piece was allowed to stand at 23 ° C. and 50% RH for 90 hours.
According to IS K-6911, the surface resistivity of the obtained laminated film was measured using a surface resistance meter with a surface resistivity comparator (MCP-TESTER (trade name, manufactured by Mitsubishi Chemical Corporation)).

The volume resistivity test piece was allowed to stand at 23 ° C. and 50% RH for 90 hours.
Based on IS K-6911, the volume resistivity in the thickness direction of the obtained laminated film was measured using a volume resistivity measuring device (R8340A type (trade name, manufactured by Advantest Corporation)).

The number of spots on the obtained laminated film was evaluated by spot inspection.

Using a mold having a heat resistance of 100 mmφ and a height of 30 mm, a container molded at 100 ° C. by a hot plate contact heating type air pressure molding machine.
It was placed in a hot air drier for 20 minutes, and the volume change before and after heating was measured to determine the volume change rate, which was used as an index of heat resistance. Volume change rate (% by volume) = [(Vo−Vt) / Vo] × 1
00 Vo: volume before heating Vt: volume after heating

Example 1 A polylactic acid-based polymer (EcoPLA4030D, manufactured by Cargill Co., Ltd.), talc (SG-1000, manufactured by Nippon Talc, average particle size: 2.0 μm), and a conductive agent (Ketjen, manufactured by International Co., Ltd.) Black EC) was replaced with polylactic acid-based polymer / talc / conductive agent = 81
The mixture was mixed at a weight ratio of / 10/10, supplied to a twin-screw extruder, melt-kneaded and discharged in a strand shape, and then pulverized into a pellet shape with a pelletizer to obtain an outer layer pellet.

The polylactic acid-based polymer, the talc, and the conductive agent (Ketjen Black EC, manufactured by International Corporation) were mixed in a weight ratio of polylactic acid-based polymer / talc / conductive agent = 87/10/3. The mixture was supplied to a twin-screw extruder, melt-kneaded and discharged in a strand form, and then pulverized into a pellet form with a pelletizer to obtain an inner layer raw material pellet.

The pellets for the outer layer and the pellets for the inner layer are supplied to each single screw extruder and extruded from one T-die.
When the thickness is outer layer / inner layer / outer layer = 10/1080/10 (μ
m) was prepared.

The surface resistivity of the obtained laminated film was 6 ×
It was 10 ⁶ Ω and the volume resistivity was 4 × 10 ⁸ Ω. Also,
There were no bumps.

Further, the obtained laminated film was brought into contact with a hot plate at 130 ° C. for 40 seconds by a pressure forming machine described in the above heat resistance evaluation method, and then cooled at a pressure of 0.04 MPa. The molded body was brought into contact with the mold for 20 seconds to obtain a molded body. The heat resistance of the obtained molded body is such that the volume change rate is 0% by volume.
And was excellent in heat resistance.

(Example 2) As the talc constituting the inner layer, SG-2000 (average particle diameter: 1.0 µm) manufactured by Nippon Talc was used, and the hot plate contact time during molding was 10 seconds. It was the same as in Example 1. As a result, the surface resistivity was 5 × 10 ⁶ Ω, the volume resistivity was 4 × 10 ⁸ Ω, the heat resistance was 0% by volume, and there were no bumps.

(Example 3) The amount of talc added in the inner layer and the outer layer in Example 2 was set to 5% (the amount reduced from 10% to 5% was compensated with a polylactic acid-based polymer), and molding was performed. Example 2 was carried out in the same manner as in Example 2 except that the hot plate contact time was changed to 40 seconds. As a result, the surface resistivity was 5 × 10 ⁶ Ω, the volume resistivity was 4 × 10 ⁸ Ω, the heat resistance was 0% by volume, and there were no bumps.

Example 4 Example 1 was carried out in the same manner as in Example 1 except that the structure of the inner layer was changed to polylactic acid-based polymer / talc / conductive agent = 90/10/0 (weight ratio). As a result, the surface resistivity was 8 × 10 ⁶ Ω and the volume resistivity was 8 × 10 ^6
14 Ω.

(Comparative Example 1) The structure of the inner layer in Example 1 was polylactic acid-based polymer / talc / conductive agent = 91/0/9, and the structure of the outer layer was polylactic acid-based polymer / talc / conductive agent = 97. /
Example 3 was carried out in the same manner as in Example 1 except that the hot plate contact time during molding was set to 70 seconds. As a result, the surface resistivity was 5
× 10 ⁶ Ω, volume resistivity 7 × 10 ⁸ Ω, heat resistance 80
By volume%, the heat resistance was poor. There were no bumps.

(Comparative Example 2) The amount of talc added to the inner layer and the outer layer in Example 1 was 0.2% (the decrease from 10% to 0.2% was compensated for by the polylactic acid-based polymer). In the same manner as in Example 1 except that the hot plate contact time during molding was set to 70 seconds. As a result, the surface resistivity was 5 × 10 ⁶ Ω, the volume resistivity was 4 × 10 ⁸ Ω, and the heat resistance was 36% by volume, which was inferior to the heat resistance. There were no bumps.

Comparative Example 3 The procedure of Example 1 was repeated, except that the heating temperature of the hot platen during molding was 115 ° C. The heat resistance of the obtained molded body was 54% by volume, which was inferior to the heat resistance.

(Comparative Example 4) In Comparative Example 1, except that the heating temperature of the hot platen at the time of molding was set to 165 ° C, a good molded product was not obtained.

(Example 5) The sheet prepared in Example 1 was slit, heated at 140 ° C for 20 seconds, and then subjected to air pressure molding to continuously form an accommodating portion capable of accommodating an IC chip to form a carrier tape. Obtained.

An IC chip was put in the obtained carrier tape and passed through a baking process at 100 ° C., but no deformation occurred.

(Comparative Example 5) The sheet prepared in Comparative Example 1 was slit, heated at 140 ° C. for 20 seconds, and then subjected to air pressure molding to continuously form the accommodating portion capable of accommodating an IC chip to form a carrier tape. Obtained.

When an IC chip was put into the obtained carrier tape and passed through a baking process at 100 ° C., deformation occurred and was not practical.

[0066]

According to the present invention, the resulting biodegradable conductive composite molded article contains a crystal component, and therefore has excellent heat resistance and can be used for a carrier tape requiring a baking step.

Since the outer layer and the inner layer of the laminated structure can contain different proportions of the conductive agent, the amount of the conductive agent used can be reduced.

When a large amount of the conductive agent is contained in the outer layer of the laminated structure, even if the amount of the conductive agent is reduced, the density of the conductive agent near the surface can be increased, and a sufficient surface resistivity can be obtained. be able to.

Further, when a conductive agent is used for the inner layer, a sufficient volume resistivity can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B65D 65/46 BSG B65D 65/46 BSG 4J002 85/86 C08K 3/00 C08K 3/00 C08L 67/04 ZBP C08L 67/04 ZBP B29K 67:00 // B29K 67:00 B29L 22:00 B29L 22:00 B65D 85/38 PSF term (reference) 3E086 AB02 AD09 BA04 BA15 BA35 BB35 BB90 CA31 3E096 AA06 BA08 CA15 CB02 EA11X FA07 FA40 GA01 4F100 AA37H AC10A AC10B AC10C AK41A AK41B AK41C BA03 BA04 BA05 BA06 BA07 BA10A BA10C CA30 EH20 EH202 GB41 JC00 JG01A JG01C YY00A YY00B YY00C 4F207 AA24 AB16 AB18 AG01 AG03 MB01 AG01 AG03 MB01 KB03 AG01 AG03 MB01 MW01 4J002 CF031 CF181 CF191 DA037 DE097 DE127 DJ046 FD117 GF00

Claims (5)

[Claims] 1. A biodegradable conductive composite molded article obtained by crystallizing a biodegradable conductive composite sheet formed from at least three layers immediately after crystallization. 2. The biodegradable conductive composite sheet, wherein the outer layer comprises a polylactic acid-based polymer, 0.3 to 15% by weight of talc, and 3 to 15% by weight of a conductive agent. The biodegradable conductive composite molded article according to claim 1, wherein the sheet comprises a polylactic acid-based polymer and 0.3 to 15% by weight of talc. 3. The biodegradable conductive composite sheet, wherein the outer layer comprises a polylactic acid-based polymer, 0.3 to 15% by weight of talc, and 3 to 15% by weight of a conductive agent. Is a sheet comprising a polylactic acid-based polymer, 0.3 to 10% by weight of talc, and 0.1 to 3% by weight of a conductive agent. Molded body. 4. A method for producing a biodegradable conductive composite molded article, comprising preheating and then thermoforming the biodegradable conductive composite sheet according to claim 1. 5. A carrier tape formed from the biodegradable conductive composite molded article according to claim 1.