JP4439571B2 - Resin separation method - Google Patents

Abstract

To provide a high purity separation method of resin materials, which method does not produce waste water and is not affected by the specific gravities and dielectric characteristics of resin materials, in recycling of resin materials as resources. A separation object including at least two types of resins with different glass transition temperatures (glass transition temperature of a first resin 1 < glass transition temperature of a second resin 2) is placed on a separating member 3. Next, primary heating is applied at a temperature between the glass transition temperatures of the first resin 1 and the second resin 2, and pressurization is additionally performed to cause the first resin 1 to adhere to the separating member 3. Subsequently, a heat history of secondary heating at a temperature higher than the primary heating temperature is applied to detach and recover the second resin 2 by restoring the shape of the second resin 2, while the first resin 1 adhering to and retained by the separating member 3 is detached by a blade 5 and the like for recovery.

Description

  The present invention relates to a technology for separating resin from a separation object in which resin pieces are mixed for the purpose of recycling used household electrical appliances.

  Recent mass production, mass consumption, and mass disposal economic activities have caused global environmental problems such as global warming and resource depletion. Under such circumstances, air conditioners, television receivers, refrigerators / freezers, etc. that have been used since the Home Appliance Recycling Law was fully enforced in April 2001 to build a recycling-oriented society. Washing machine recycling is obligatory.

  Conventionally, home appliances that are no longer needed are recycled at home appliance recycling factories after being crushed and separated by material using magnetism, wind power, vibration, and the like. In particular, by using a specific gravity sorting device or a magnetic sorting device, the metal material is recovered with high purity for each material such as iron, copper, and aluminum, and a high recycling rate is realized.

  On the other hand, in the resin material, polypropylene (hereinafter referred to as PP), which is a light specific gravity, is separated from high specific gravity by specific gravity sorting using water and recovered with relatively high purity. However, specific gravity selection using water is a major issue in that a large amount of wastewater is generated and that polystyrene (hereinafter referred to as PS) and acrylonitrile styrene butadiene (hereinafter referred to as ABS) having similar specific gravity cannot be separated. ing. In recent years, demand for filler-filled polypropylene, which has a high specific gravity, has been increasing, and this cannot be handled by conventional specific gravity separation.

The following (Patent Document 1) and (Patent Document 2) have proposed a sorting method in consideration of the above-mentioned problems related to the recycling of resin materials.
(Patent Document 1) is a separation method that utilizes the difference in melting temperature between two types of resins to be separated, and is made of a pair of heat-resistant steel so as to be an intermediate temperature between the melting temperatures of the two types of resins to be separated. Two types of resins are obtained by heating the circumferential surface, passing two kinds of resins to be separated into the gap between the heated circumferential surfaces, and attaching only a resin having a low melting temperature to the heated circumferential surface. It is a method of separating.

Further, (Patent Document 2) is a sorting method using a difference in dielectric loss between resin materials. It is a method of applying electromagnetic heating to an object to be separated in which two or more types of resin are mixed and subjecting it to dielectric heating, and utilizing the difference in melting characteristics due to the difference in heat generation property of each resin material. In this case, there is no drainage, and the resin material is not affected by the specific gravity.
Japanese Utility Model Publication No. 4-126822 JP 2002-234031 A

  However, in (Patent Document 1), a low-polar molecular substance having low adhesion to other substances such as PP and PS becomes unstable in the adhesion strength of the molten resin and cannot be separated with high purity. In addition, if a low melting point resin and a high melting point resin pass through the clearance between the circumferential surfaces heated simultaneously, an unmelted high melting point resin is attached to the molten low melting point resin, which causes a problem that separation is not possible. .

Moreover, in (patent document 2), since the resin material with a near dielectric loss characteristic cannot be fractionated, collection | recovery with high purity is difficult.
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described conventional problems and to provide a resin separation method that does not generate waste water and is not affected by the specific gravity and dielectric loss characteristics of the resin material.

In the resin separation method according to claim 1 of the present invention, a separation object in which two or more kinds of resins having different glass transition temperatures and yield stresses are mixed is placed on a separation member and subjected to primary heating and pressurization, The temperature of the primary heating at that time is set to a temperature lower than the glass transition temperature of one or more kinds of resins among the resins and higher than the glass transition temperature of one or more kinds of resins, The compressive yield at the temperature of the primary heating is set at a pressure higher than the compressive yield stress of the resin having the highest compressive yield stress among the resins having a glass transition temperature lower than the temperature of the primary heating. After the resin having a stress lower than the applied pressure is adhered to the separating member and the pressurized applied pressure is released, the resin not adhered to the separating member or the resin having a small adhesive force is separated from the separating member. In addition, resin The separating member attached to the secondary heating, the temperature of the secondary heating at that time, is set to a temperature lower than the lowest melting point of the resin melting point of the hot and the separation object than the primary heating temperature Thus, only the resin having a glass transition temperature lower than the temperature of the primary heating is attached to the separation member, and the resin attached to the separation member is separated from the separation member and separated.

  The resin fractionation method according to claim 2 of the present invention is the resin separation method according to claim 1, wherein the primary heating temperature is the lowest among the two or more kinds of resins having different glass transition temperatures and yield stresses. It is characterized in that the temperature is set between the resin and the resin having the next lower glass transition temperature.

  The resin fractionation method according to claim 3 of the present invention is the resin separation method according to claim 1, wherein the temperature of the primary heating is the highest glass transition temperature among the two or more types of resins having different glass transition temperatures and yield stresses. The temperature is set between the resin and the resin having the next highest glass transition temperature.

The resin fractionation method according to claim 4 of the present invention is characterized in that, in any one of claims 1 to 3, the pressure is a pressure equal to or greater than 1.2 times the compressive yield stress. .
The resin separation method according to claim 5 of the present invention is the resin separation method according to any one of claims 1 to 4, wherein the difference in the maximum thickness with respect to the minimum thickness of the resin in the pressing direction in which the object to be separated is placed on the separation member is 5. It is within 5 mm.

  The resin sorting method according to claim 6 of the present invention is the resin sorting method according to any one of claims 1 to 5, wherein the thickness of the resin in the pressurizing direction in which the sorting object is placed on the sorting member is 0.5 mm or more and 6 It is the range of 0.0 mm or less.

  A resin separation method according to a seventh aspect of the present invention is the resin separation method according to any one of the first to fifth aspects, wherein the thickness of the resin in the pressure direction in which the separation object is placed on the separation member is 1.0 mm or more and 6 It is the range of 0.0 mm or less.

  The resin separation method according to an eighth aspect of the present invention is the resin separation method according to any one of the first to fifth aspects, wherein the thickness of the resin in the pressing direction in which the separation object is placed on the separation member is 1.0 mm or more and 3 It is the range of 0.0 mm or less.

  In the resin fractionation method according to claim 9 of the present invention, in any one of claims 1 to 8, the temperature increase rate of the resin having a glass transition temperature lower than the temperature of the primary heating in the secondary heating. The temperature rise rate of the resin having a glass transition temperature higher than the temperature of the primary heating is smaller.

  The resin fractionation method according to claim 10 of the present invention is the resin fractionation method according to any one of claims 1 to 8, wherein the temperature increase rate of the resin having a glass transition temperature lower than the temperature of the primary heating in the secondary heating. The heat treatment at the temperature reached temperature of the resin having a glass transition temperature lower than the temperature of the primary heating by making the temperature rise rate lower than that of the resin having a glass transition temperature higher than the temperature of the primary heating. The time is shorter by 5 seconds or more than the resin having a glass transition temperature higher than the temperature of the primary heating, and the temperature rising time of the resin having a glass transition temperature lower than the temperature of the primary heating is 60 seconds or less. It is characterized by being.

  The resin fractionation method according to claim 11 of the present invention is the resin fractionation method according to any one of claims 1 to 10, wherein the separation object is polypropylene, polyethylene, polylactic acid, polyvinyl chloride, polystyrene, acrylonitrile styrene, acrylonitrile butadiene styrene. And at least any one of polycarbonate.

  The resin fractionation method according to claim 12 of the present invention is characterized in that, in any one of claims 1 to 10, the fractionation object is composed of polypropylene and at least one of polystyrene or acrylonitrile butadiene styrene.

  The resin fractionation method according to claim 13 of the present invention is the resin fractionation method according to claim 12, wherein the temperature of the primary heating is set to 15 ° C. or more and lower than the glass transition temperature of the resin species of all fractionation objects other than polypropylene, The temperature of the secondary heating is set to 70 ° C. or more and 155 ° C. or less and higher than the temperature of the primary heating.

  The resin fractionation method according to claim 14 of the present invention is the resin fractionation method according to claim 12, wherein the temperature of the primary heating is set to 15 ° C. or more and lower than the glass transition temperature of the resin species of all fractionation objects other than polypropylene, The temperature of the secondary heating is set to 100 ° C. or more and 155 ° C. or less and higher than the temperature of the primary heating.

  According to this configuration, by placing the resin separation object within the set thickness on the separation member and performing heating and pressurization between the glass transition temperatures of the resin of the separation object, the separation is performed. Through the member, the resin can be separated into a resin having a glass transition temperature higher than the heating temperature and a resin having a lower glass transition temperature than the heating temperature. Thereby, a desired resin can be separated with high purity from the separation object, which is impossible to be separated by the conventional technique.

(Embodiment 1)
1 to 14 show Embodiment 1 of the present invention.
FIG. 1A to FIG. 1F show a process of separating a resin from a separation object in which two kinds of a first resin 1 and a second resin 2 having different glass transition temperatures and yield stresses are mixed. ing.

In FIG. 1A, the separation object is placed on the separation member 3. Here, the glass transition temperature of the first resin 1 is lower than the glass transition temperature of the second resin 2.
In FIG. 1B, primary heating is performed. The heating temperature at that time is a temperature between the glass transition temperatures of the first resin 1 and the second resin 2.

  At this time, the first resin 1 and the second resin 2 are pressed against the separation member 3 by the flat plate 4. The magnitude of the applied pressure is equal to or greater than the compressive yield stress of the first resin 1, and at least the first resin 1 and the second resin 2 are heated and pressurized in this state, so that at least the first The resin 1 adheres to the separation member 3. In other words, since the first resin 1 at this time is heated and pressurized at a temperature equal to or higher than the glass transition temperature and higher than the compressive yield stress, it is plastically deformed and adheres to the separation member 3. Moreover, when the applied pressure of the heating and pressing is equal to or higher than the compressive yield stress of the second resin 2, the second resin 2 also deforms and adheres to the separation member 3, but at a temperature lower than the glass transition temperature. If a heat history higher than the primary pressurizing temperature is applied after the pressure is released due to processing deformation, the shape is restored to the state before pressurization and is detached from the separation member 3. Further, when the pressure applied by heating and pressurization is smaller than the compressive yield stress of the second resin 2, the second resin 2 does not adhere to the separation member 3. In addition, when the board | plate material which has uneven | corrugated shape on the surface, such as a metal net | network or a punching metal, is used for the separating member 3, and favorable adhesive strength is obtained.

  Next, as shown in FIG. 1C, the pressure applied is released, and the separating member 3 is tilted, or the separating member 3 is slightly vibrated to adhere to the resin adhering to the separating member 3. Can be separated from unresined resin. Here, the second resin 2 b not attached to the separation member 3 is detached from the separation member 3. The second resin adhering to the sorting member 3 is shown as 2a.

  When the material to be separated includes a material (metal, paper, wood piece, thermosetting resin, etc.) that does not adhere to the separation member 3 by the heating and pressurization of FIG. 1B, the second resin 2b. In the same manner as above, the first resin 1 and the second resin 2a adhering to the separation member 3 can be separated and removed as unbonded materials.

  Next, in FIG. 1D, the secondary heating is performed at a temperature higher than the primary heating temperature and lower than the melting point of the first resin 1 and the second resin 2 having a lower melting point. As a result, the shape of the second resin 2a that has been adhered to the separation member 3 is restored to the state before pressurization, and is separated from the separation member 3 or in a state where the adhesion strength to the separation member 3 is extremely low. Therefore, the first resin 1 attached to the separating member 3 can be separated as shown in FIG. 1E by inclining the separating member 3 or by slightly vibrating the separating member 3.

The primary heating and the secondary heating may be performed by bringing the separation member 3 into contact with the hot plate, and a radiation method or a hot air method can be employed without any particular limitation.
Next, in FIG.1 (f), it can collect | recover by scraping off the 1st resin 1 adhering to the separation member 3 with the blade 5 grade | etc.,. At this time, if the elastic modulus of the first resin 1 is reduced by performing the third heating on the first resin 1, the separation of the first resin 1 and the separating member 3 is facilitated.

  Generally, when a resin material is heated, there is a temperature at which the rigidity is rapidly lowered and the fluidity is increased in a narrow temperature range from a state in which the resin material is hard and does not have fluidity at a low temperature. The temperature at which such changes in physical properties occur is called the glass transition temperature.

  The following (Table 1) is the result of measuring the glass transition temperature of PP, PE, PLA, PVC, PS, AS, ABS and PC with a differential scanning calorimeter (model name: DSC220) manufactured by Seiko Instruments Inc. . A clear difference in glass transition temperature due to the difference in each resin was confirmed.

なお、表中のＳＰ２はScientific Polymer Products.Inc.（米国）、ＵＭＧはユーエムジー・エービーエス株式会社である。

In the table, SP2 is Scientific Polymer Products. Inc. (USA) and UMG is UMG ABS Co., Ltd.

  When pressure is applied to the resin material and the applied pressure is increased, the displacement (strain) starts to increase suddenly (yield) when the pressure exceeds the elastic limit of the resin material. Point). The pressure applied when this point is reached is defined as the compressive yield stress.

  FIG. 2 is a result of measuring the compressive yield stress of each resin material in (Table 1) according to temperature using a compression stress measuring instrument (model name: TCM10000 (compression load speed 1 mm / min)) manufactured by Tokyo Shiki Seisakusho. is there.

  For each resin material, the compressive yield stress decreased as the temperature increased, and when the temperature exceeded the glass transition temperature, it was below the measurement limit. This is because the fluidity of the resin sharply increases above the glass transition temperature, and it can be seen that, at the glass transition temperature or higher, each resin easily undergoes compressive deformation at a low applied pressure.

Example 1
A method for separating a desired resin from a separation object containing PP and PS will be described.
Here, the first resin 1 is PP and the second resin 2 is PS.

  By placing the separation member 3 and the object to be separated on the pressure plate of the flat plate press, pressurizing for 60 seconds with a 3.0 mm spacer sandwiched to a predetermined thickness, and removing 1.0 mm or less of resin The thickness in the pressing direction was made uniform in the range of 1.0 mm to 3.0 mm.

  In addition, it is possible to make the resin uniform to a desired thickness by a compression method using a roll instead of a flat plate press. In the case of rolls, the thickness of the resin can be made uniform continuously in both vertical and horizontal types. At this time, it is efficient by optimizing the roll gap, roll diameter, roll rotation speed, and roll number as appropriate. In addition, the resin thickness can be made uniform.

For the separating member 3, a stainless steel wire mesh having an opening of 0.28 mm, a wire diameter of 0.23 mm, and a size of 150 mm × 150 mm was used.
Next, the separation object is placed on the separation member 3 so that the resins do not overlap each other at a ratio of 45 to 55% with respect to the entire area of the separation member 3, and the separation member 3 is used as a hot plate of a hot press machine. It was placed on top, subjected to primary heating at 70 ° C., and heated and pressurized at a pressure of 20000 kgf for 30 seconds.

  Next, the separation member 3 on which the object to be subjected to heat and pressure is placed is placed on a hot plate, subjected to secondary heating at 150 ° C. for 20 seconds, and the separation member 3 is inclined to form a second resin. 2 was collected separately.

  Next, the separation member 3 from which the second resin 2 has been separated and removed is placed on the hot plate, subjected to tertiary heating at 150 ° C. for 30 seconds, and stainless steel having a thickness of 1 mm on the hot plate. The PP of the first resin 1 adhering to the sorting member 3 was scraped off and collected by using a blade made from the material.

  The qualitative analysis of the resin fractionated by the secondary heating and the tertiary heating was performed with an infrared absorption analyzer, and the quality of the resin fractionation was confirmed. As a result, the resin released by the secondary heating was PS having a purity of 100%, and the resin scraped off by the blade by the tertiary heating was PP having a purity of 100%.

  In addition, it is more preferable that the particle diameter of the object to be separated is made uniform with a sieve before it is made uniform to a predetermined thickness. First, remove coarse particles in the separation object using a sieve with an opening of 8.5 mm, and then remove small mixed pieces and powder in the separation object using a sieve with an opening of 1.0 mm. It is possible to make the particle diameter of the object uniform within a certain range.

  In addition, the adhesive strength of resin becomes large, so that the temperature of primary heating is high, and the tendency for peeling of resin to become easy is seen, so that the temperature of 2nd, 3rd heating is high. However, if the heating is performed at a temperature equal to or higher than the melting point of the resin in the separation target, the resin melts, so that adhesion and peeling cannot be performed completely, and efficient separation cannot be performed. Therefore, the heating temperature must not exceed the melting point of the lowest resin of the separation object.

Hereinafter, the influence of the pressure applied during heating and pressurization, the temperature of the first and second heating, the thickness of the resin, and the impurities on the quality of the resin separation will be described in order.
− Effect of pressure during heating and pressurization −
FIG. 3 shows the relationship between the pressure applied during heating and pressurization and the PP recovery rate in the separation of the separation object including PP and PS. The horizontal axis represents the ratio of the pressure applied to the object to be separated at the temperature of the primary heating to the compressive yield stress of PP at the primary heating temperature. The PP recovery rate (%) on the vertical axis is the percentage (%) of the PP amount recovered by the third heating with respect to the total PP amount contained in the separation object.

  As shown in FIG. 3, it was found that the recovery rate of PP is improved when the applied pressure is increased. By making the applied pressure equal to or higher than the compression yield stress of PP, PP can be adhered and held on the separation member, and PP can be recovered from the separation object. Further, it has been found that the compression yield stress of PP with respect to the pressure of PP is preferably 1.2 times or more at which the PP recovery rate becomes 100%.

  When the same verification was performed on resins other than PP listed in Table 1, it was possible to recover any resin with a yield compression stress or higher, and a high recovery rate with 1.2 times or more the yield compression stress or higher. It became.

Note that if the applied pressure is excessively large, problems such as breakage of the sorting member, increase in load on the equipment, and destruction of the resin occur, so the upper limit value is set according to the sorting member and equipment specifications.
− Effect of primary heating temperature −
FIG. 4 shows the relationship between the primary heating temperature and the PP recovery rate in the separation of the separation object including PP and PS. FIG. 5 shows the relationship between the primary heating temperature and the purity of PP in the separation of the separation object including PP and PS. The PP purity (%) on the vertical axis in FIG. 5 is a percentage (%) of the amount of PP recovered by the third heating with respect to the total amount of resin recovered by the third heating.

  The solid line in FIG. 4 is a curve heated and pressurized for 30 seconds at a pressure of 20000 kgf. When the temperature of the primary heating was 40 ° C. or lower, PP did not adhere to the separation member 3, so that the separation member 3 could not hold the PP and could not be separated and collected. When the temperature of the primary heating is heated in the region of 60 ° C. or higher to 90 ° C., the adhesion strength of PP is increased, and the purity and recovery rate of PP are set to 100 by the operations of the secondary heating and the tertiary heating. % Was possible.

  The dotted line in FIG. 4 is a curve heated and pressurized for 30 seconds at a pressure of 40,000 kgf. Since the adhesion strength of PP increases at 15 ° C. or higher, the purity and recovery rate of PP can be made 100%. there were. Under such high pressure conditions, PP could be fractionated in a low temperature range. However, when the pressure was higher than 40000 kgf, the separation member was damaged.

  Further, as shown in FIG. 5, when the temperature of the primary heating is set to 100 ° C. or higher, not only the glass transition temperature of PP but also the glass transition temperature of PS is increased. The shape of PP could not be restored, and the purity of PP decreased.

  From the above, it is necessary to perform primary heating at 15 ° C. or higher and 90 ° C. or lower for the separation object including PP and PS, and the primary pressure is 60 ° C. or higher and 90 ° C. or lower when the applied pressure is 20000 kgf. It has been found that heating is more preferable.

  FIG. 6 shows the relationship between the primary heating temperature and the PP recovery rate in the separation of the separation object including PP and ABS. FIG. 7 shows the relationship between the temperature of primary heating and the purity of PP in the separation of the separation object including PP and ABS.

  As shown in FIGS. 6 and 7, the same tendency as the separation of the separation object including PP and PS was confirmed. As shown in FIG. 6, when the temperature of the primary heating was 40 ° C. or lower, PP could not be attached to and held on the separation member 3 and could not be recovered. When the temperature of the primary heating is in the range of 60 ° C. to 110 ° C., the adhesion strength of PP increases, and the purity and recovery rate of PP can be made 100% by the operation of the second and third heating. there were. The dotted line in FIG. 6 is a curve heated and pressurized for 30 seconds at a pressure of 40,000 kgf. Since the adhesion strength of PP increases at 15 ° C. or higher, the purity and recovery rate of PP can be made 100%. there were.

  Further, as shown in FIG. 7, when the temperature of the primary heating is set to 120 ° C. or higher, not only PP but also ABS becomes larger than the glass transition temperature, so that the shape of the ABS cannot be restored by the secondary heating, and PP The purity decreased.

  As described above, in the separation object including PP and ABS, it is necessary to perform the primary heating at 15 ° C. or more and 110 ° C. or less. It has been found that heating is more preferable.

− Effect of secondary heating temperature −
FIG. 8 shows the relationship of the purity of PP and PS with respect to the secondary heating temperature in the separation of the separation object including PP and PS. FIG. 9 shows the relationship between the recovery rate of PP and the secondary heating temperature in the separation of the separation object including PP and PS.

  The purity (%) of PS on the vertical axis in FIG. 8 is the percentage (%) of the amount of PS removed and recovered by secondary heating with respect to the total amount of resin released and recovered by secondary heating. On the other hand, the purity (%) of PP on the vertical axis in FIG. 8 is the amount of PP recovered by tertiary heating with respect to the total amount of resin fractionally recovered by tertiary heating after secondary heating at a predetermined temperature. Percentage.

  As shown in FIG. 8, when the temperature of the secondary heating is lower than 70 ° C., the temperature of the secondary heating is lower than the primary heating, and the shape of the PS does not restore to the state before pressurization. PS did not leave from 3, and PP and PS could not be separated efficiently. When the temperature of the secondary heating was set to 70 ° C. or higher, the restoration of the shape of the PS started, so that the PS separated from the separation member, and the PP and PS could be separated.

  When the secondary heating temperature was in the range of 100 ° C. to 155 ° C. for 20 seconds, the PP purity could be 100%. In addition, when the secondary heating temperature was higher than 155 ° C. as shown in FIG. 9, PP was melted and welded to the separation member 3, so that the PP recovery rate was lowered.

  As a result of performing the same verification with other resins described in (Table 1), the secondary heating is performed at a temperature lower than the melting point of the lowest resin of the separation target and at a temperature higher than the primary heating temperature. There was a need.

  From the above, in the separation object including PP and PS, the separation object including PP and ABS, and the separation object including PP, PS and ABS, the temperature of the primary heating is 70 ° C. or more and 155 ° C. or less. It is necessary to perform secondary heating at a higher setting, and it is more preferable to perform secondary heating at a temperature of 100 ° C. or higher and 155 ° C. or lower and higher than the temperature of the primary heating. I found.

− Effect of resin thickness −
When the shape variation of the separation target is large, pressure variation occurs during pressurization, and a good adhesion phenomenon cannot be obtained. Therefore, it is preferable that the thickness of the separation target is equalized in advance. It was found that when the difference between the thickness in the pressing direction and the maximum thickness with respect to the minimum thickness of the resin is within 5.5 mm, the pressure is applied almost uniformly and a good adhesion phenomenon is obtained.

  In order to investigate the influence of thickness, the thickness was adjusted with a flat plate press using a spacer. The following (Table 2) is the result of measuring the purity and recovery rate of PP and PS with respect to the range of thickness in the pressing direction of the separation object.

平板プレス機の加圧板の上に分別部材３と分別対象物を載せ、所定の厚みになるように６．０ｍｍのスペーサーを挟んで６０秒間加圧し、さらに０．５ｍｍ未満の樹脂を取り除くことで、加圧方向の厚みを０．５ｍｍ以上かつ６．０ｍｍ以下の範囲に均一化し、最小厚みに対する最大厚みの差を５．５ｍｍ以内に調整した。このとき、ＰＳの純度が９０％以上となり、他の樹脂分別方法と組み合わせることにより、多くの樹脂材料メーカーで樹脂の再生が可能となるために好ましい。

By placing the separation member 3 and the object to be separated on the pressure plate of the flat plate press, pressurizing for 60 seconds with a 6.0 mm spacer so as to have a predetermined thickness, and removing resin less than 0.5 mm The thickness in the pressing direction was made uniform in the range of 0.5 mm or more and 6.0 mm or less, and the difference in maximum thickness with respect to the minimum thickness was adjusted to 5.5 mm or less. At this time, the purity of PS is 90% or more, and it is preferable because many resin material manufacturers can regenerate the resin by combining with other resin separation methods.

  Similarly, when the thickness of the resin is made uniform within the range of 1.0 mm or more and 6.0 mm or less by adjusting the thickness with a spacer or the like, the PS purity becomes 98% or more, and directly by the resin material manufacturer as a recycled material. This is more preferable because the purity is such that regeneration is possible.

Furthermore, it is more preferable that the thickness of the resin is uniformized in the range of 1.0 mm or more and 3.0 mm or less because the purity and recovery rate of PP and PS are 100% respectively.
As a result of conducting the same verification with the other resins listed in Table 1, the same phenomenon as that of the PP and PS resins was confirmed with the other resins.

− Effect of rate of temperature increase in secondary heating −
FIG. 10 shows the relationship of the adhesive strength between the PP and PS separation members with respect to the secondary heating time in the separation of the separation object including PP and PS. The object to be separated was used by making the thickness in the pressing direction uniform in the range of 0.5 mm or more and 6.0 mm or less in advance. The adhesive strength of PP and PS was measured by using a separation gauge and horizontal shear stress using a force gauge FGP-20 manufactured by Nidec Sympos. In order to easily remove the separation object from the separation member by tilting or slight vibration, the adhesive strength is preferably zero. Moreover, in order to stably adhere and maintain the separation object to the separation member, it is preferable that the adhesive strength is 2N or more. That is, in the separation of the separation object including PP and PS, a good separation result can be obtained when the PS adhesive strength is zero and the PP adhesive strength is 2N or more after the secondary heating.

  As shown in FIG. 10, it was found that the adhesive strength of PS decreased as the secondary heating time increased, and that the PS adhesive strength became zero when the secondary heating time was 20 seconds or more. Regarding PP adhesive strength, PP with a thickness of 1 mm or more showed no decrease in adhesive strength. However, with PP having a thickness of less than 1 mm, the adhesive strength decreases as the secondary heating time increases, and when the secondary heating time is 20 seconds or longer, the adhesive strength may be 2 N or lower. It has been found that this is the cause of the decrease in the purity of PP and the recovery rate of PP.

  Therefore, a means for suppressing a decrease in the adhesive strength of PP having a thickness of less than 1 mm was examined, and as a result, the PP temperature increase rate in the secondary heating was made smaller than the PS temperature increase rate. The present inventors have found a means for substantially shortening the secondary heating time and suppressing a decrease in PP adhesive strength in the secondary heating.

The temperature increase rate of PP and PS can be easily controlled by utilizing the difference in the infrared absorption characteristics of the resin. FIG. 11 and FIG. 12 are infrared absorption curves of PP and PS. When irradiated with infrared rays having a wave number band of 500 to 1200 cm ⁻¹ which is not absorbed by PP and is absorbed only by PS, PS is preferentially heated. . Moreover, as a result of simultaneously heating PP and PS using a germanium-based infrared filter and a near-infrared panel heater having the characteristics as shown in FIG. 13, the temperature increase rate of PP is higher than the temperature increase rate of PS. It was confirmed with good reproducibility that it became smaller.

  (Table 3) reduces the temperature increase rate of PP by performing the secondary heating in the separation of the separation object including PP and PS using the germanium infrared filter and the near infrared panel heater, As a result of measuring the purity and recovery rate of PP and PS when the substantial heating time at the temperature rise temperature (150 ° C.) was shortened by 5 seconds with respect to PS, The result of the next heating is also shown. From Table 3, it was confirmed that the purity and recovery rate of PP and PS were improved by shortening the heating time of PP.

図１４は、ＰＳとＰＰの昇温到達温度での加熱時間の差とＰＰおよびＰＳの純度の関係を示している。ＰＰの加熱時間を５秒以上短くすることで、ＰＳ樹脂の純度が９８％以上になり、リサイクル材として直接、樹脂材料メーカーにより再生が可能となる純度になることが見出せた。しかしながら、ＰＰが昇温到達温度に達するまでの時間すなわち昇温時間が６０秒を超えると、第２次加熱後の接着強度が２Ｎ以下になるものが出はじめるため、ＰＰの加熱時間がＰＳに対して５秒以上短く、かつ、昇温時間が６０秒以下であることが好ましい。

FIG. 14 shows the relationship between the difference in heating time between the temperature at which PS and PP rise in temperature and the purity of PP and PS. It was found that by shortening the PP heating time by 5 seconds or more, the purity of the PS resin becomes 98% or more, and the purity can be directly recycled as a recycled material by a resin material manufacturer. However, since the time until the PP reaches the temperature rise, that is, the temperature rise time exceeds 60 seconds, the adhesive strength after the second heating starts to become 2N or less, so the PP heating time becomes PS. On the other hand, it is preferable that the heating time is shorter than 5 seconds and the heating time is shorter than 60 seconds.

(Embodiment 2)
15 to 17 show a second embodiment of the present invention.
15 (a) to 15 (f) show a resin from a separation object in which three kinds of first resin 6, second resin 7 and third resin 8 having different glass transition temperatures and yield stresses are mixed. The process of separating is shown.

  In FIG. 15A, the separation object is placed on the separation member 3. Here, the glass transition temperature of the first resin 6 is lower than the glass transition temperature of the second resin 7. The glass transition temperature of the second resin 7 is lower than the glass transition temperature of the third resin 8.

  In FIG. 15B, primary heating is performed. The heating temperature at that time is equal to or higher than the glass transition temperature of the first resin 6 and is lower than the glass transition temperatures of the second resin 7 and the third resin 8.

  At this time, the first resin 6, the second resin 7, and the third resin 8 are pressed against the separation member 3 by the flat plate 4. The magnitude of the applied pressure is equal to or greater than the compressive yield stress of the first resin 6, and the first resin 6, the second resin 7, and the third resin 8 are heated and pressurized in this state. As a result, at least the first resin 6 adheres to the separation member 3.

  Further, the second resin 7 and the third resin 8 are each deformed when the pressure applied by heating and pressurization is equal to or greater than the compressive yield stress of each of the second resin 7 and the third resin 8. Although it adheres to the separation member 3, if a heat history higher than the pressurization temperature is applied after pressure release due to processing deformation at a temperature lower than the glass transition temperature, the shape is restored to the state before pressurization, and the separation is performed. Detached from member 3.

When the pressure applied by heating and pressing is smaller than the compressive yield stress, the second resin 7 and the third resin 8 do not adhere to the separation member 3.
Next, as shown in FIG. 15C, when the pressurization pressure is released, the second resin 7 and the third resin 8 are not attached to the separation member 3, and the same reason as in the first embodiment. Thus, by separating or finely vibrating the separating member 3, it can be separated from the first resin 6 attached to the separating member 3.

  In FIG. 15D, the secondary heating is performed at a temperature higher than the primary heating temperature and lower than the melting point of the first resin 6, the second resin 7 and the third resin 8 having a low melting point. By doing so, the second resin 7 and the third resin 8 are restored to their pre-pressurized state and are not attached to the separation member 3 or have a very low adhesion strength. 3 can be separated from the first resin 6 as shown in FIG.

  The first resin 6 adhered and held on the separating member 3 can be recovered by scraping it off with a blade 5 or the like as shown in FIG. At this time, if the elastic modulus of the first resin 6 is reduced by performing the third heating on the first resin 6, the separation of the first resin 6 and the separation member 3 is facilitated.

  As described above, when three types of resins having different glass transition temperatures and yield stresses coexist, it has been found that a method of increasing the purity by adhering and holding the separation member 3 in order from a resin having a lower glass transition temperature is preferable. Note that the second resin 7 and the third resin 8 separated from the separation member 3 can be separated by repeating the same operation.

  FIG. 16 shows the relationship between the recovery rate of PP and the primary heating temperature in the fractionation of the resin mixture containing PP, PS and ABS. FIG. 17 shows the relationship between the purity of the recovery rate of PP and the primary heating temperature in the fractionation of the resin mixture containing PP, PS, and ABS.

  As shown in FIG. 16, when the temperature of the primary heating is 40 ° C. or less, PP does not adhere to the separation member 3, so that the separation member 3 cannot be adhered and held by the separation member 3, and can be collected separately. could not. When the primary heating temperature is 60 ° C. or higher and 90 ° C. or lower, the subsequent secondary heating and tertiary heating operations are performed, so that the purity and recovery rate of PP is 100%. It was possible to do. The dotted line in FIG. 16 is a curve obtained by heating and pressurizing for 30 seconds at a pressure of 40,000 kgf. Since the adhesion strength of PP increases at 15 ° C. or higher, the purity and recovery rate of PP can be made 100%. there were.

  In addition, as shown in FIG. 17, when the temperature of the primary heating is set to 100 ° C. or higher, not only the glass transition temperature of PP but also the glass transition temperature of PS is exceeded. could not.

  From the above, it is necessary to perform primary heating at 15 ° C. or more and 90 ° C. or less for the separation object including PP, PS and ABS, and when the applied pressure is 20000 kgf, It has been found that it is more preferable to perform the primary heating.

(Embodiment 3)
FIG. 18 shows a third embodiment of the present invention.
18 (a) to 18 (f), there are three types of first resin 6, second resin 7 and third resin 8 having different glass transition temperatures and yield stresses as in the second embodiment. The process which sorts resin from the mixed separation subject is shown.

  In FIG. 18 (a), the separation object is placed on the separation member 3. Here, the glass transition temperature of the first resin 6 is lower than the glass transition temperature of the second resin 7. The glass transition temperature of the second resin 7 is lower than the glass transition temperature of the third resin 8.

  In FIG. 18B, primary heating is performed. The heating temperature at that time is equal to or higher than the glass transition temperature of the first resin 6 and the second resin 7 and is lower than the glass transition temperature of the third resin 8.

  At this time, the first resin 6, the second resin 7, and the third resin 8 are pressed against the separation member 3 by the flat plate 4. The magnitude of the applied pressure is equal to or greater than the compressive yield stress of the first resin 6 and the second resin 7 having a high compressive yield stress. In this state, the first resin 6, By heating and pressurizing the second resin 7 and the third resin 8, at least the first resin 6 and the second resin 7 adhere to the separation member 3. In other words, the first resin 6 and the second resin 7 are equal to or higher than the glass transition temperature of the first resin 6 and the second resin 7 and the compressive yield stress of each of the first resin 6 and the second resin 7. As described above, since it is heated and pressurized, it plastically deforms and adheres to the separation member 3.

  The third resin 8 is deformed and adheres to the separation member 3 when the pressure of the heating and pressurization is equal to or higher than the compression yield stress of the third resin 8, but is deformed at a temperature lower than the glass transition temperature. Therefore, when a heat history higher than the pressurization temperature was applied after the pressure was released, the shape was restored to the state before pressurization and detached from the separation member 3.

When the pressure of the heating and pressurization was smaller than the compressive yield stress of the third resin 8, the third resin 8 did not adhere to the separation member 3.
Next, when the pressurizing pressure is released as shown in FIG. 18 (c), if the third resin 8 is not attached to the separation member 3, it is inclined or slightly vibrated for the same reason as in the first embodiment. Thus, it was possible to separate from the resin that was adhered.

  Next, in FIG. 18D, secondary heating is performed. The temperature at that time is a temperature higher than the temperature of the primary heating and a temperature lower than the melting point of the resin having the lower melting point among the first resin 6, the second resin 7 and the third resin 8. As a result, the shape of the third resin 8 is restored to the state before pressurization, and the third resin 8 is not attached to the separation member 3 or is in a state of extremely low adhesion, so that the separation member 3 is inclined or slightly vibrated. Thus, as shown in FIG. 18E, the first resin 6 and the second resin 7 can be separated.

  The first resin 6 and the second resin 7 adhered and held on the separation member 3 can be recovered by scraping them with a blade 5 or the like as shown in FIG. At this time, if the elastic modulus of the first resin 6 and the second resin 7 is reduced by performing the third heating on the first resin 6 and the second resin 7, the first resin 6 and Separation of the second resin 7 and the separation member 3 is facilitated.

  As described above, when three types of resins having different glass transition temperatures and yield stresses coexist, it has been found that a method of increasing the purity by adhering and holding the separation member 3 in order from the resin having the higher glass transition temperature is preferable. The first resin 6 and the second resin 7 separated from the separation member 3 can be separated by repeating the same operation.

− Presence of impurities −
Even in the case where impurities other than the desired resin are contained in the separation object, it is possible to similarly separate the desired resin from the separation object using the difference between the glass transition temperature and the yield stress.

  When rubber, tape, low-melting point resin, etc. are included in the impurity component, some of the impurities attached by heating and pressing may not be removed by secondary heating, and some of the impurities may be scraped off with a blade. It mixes with the desired resin to be peeled and collected, and the purity of the desired resin is lowered. If the impurity component contains an impurity having a glass transition temperature equal to or higher than the temperature of the primary heating, the secondary heating causes a part of the impurity to be restored to its pre-pressurized state and separated. The purity of the resin that is detached and recovered by the secondary heating is lowered. Moreover, when a component of impurities includes metal, wood, paper, and the like, the impurities do not adhere to the separation member, and therefore can be separated from a desired resin.

  When impurities are contained in the separation target as described above, the purity of the desired resin varies depending on the type and content of the impurities, but the desired resin can be separated. Therefore, the desired resin can be separated even if some impurities are mixed in the process of the present invention.

  A verification experiment for high-purity fractionation of PP according to the present invention was performed using samples of crushed plastic fractionation objects of waste home appliances containing PP, PS, ABS and impurities. For the refrigerator, which is a used household electrical appliance, the sample is first hand-sorted and the internal parts including the compressor and high-purity resin parts are taken out, and then crushed by a crusher. It is crushing waste having a maximum particle diameter of about 10.0 mm obtained by taking out metal or the like through a process such as electric separation.

  A part of the sample was extracted in advance, and the PP and impurity contents in the sample were analyzed by known infrared absorption analysis, specific gravity analysis, visual inspection and palpation, and then PP separation was performed. The results of measuring the PP content (%) in the sample, the impurity content (%) in the sample, and the purity (%) of the separated and recovered PP are shown in Table 4 below.

この（表４）より、不純物が混入した場合でも、リサイクル材として再生が可能となる純度を維持することが可能であることを実証できた。

From this (Table 4), it was proved that even when impurities were mixed, it was possible to maintain the purity that could be recycled as a recycled material.

  As described above, the present invention is particularly effective for sorting PP, PS, and ABS that are particularly abundant in used home appliances. Conventionally, it is also effective for filler-filled resin, which cannot be separated by specific gravity separation, or for PLA that will grow in future demand.

  The separation method of the separation object using the difference in glass transition temperature of the present invention is a resin resource as a separation method for recycling a specific resin material from a mixed piece of resin contained in waste home appliances and general waste. Applicable to circulation.

Process sectional drawing which shows the resin classification method of Embodiment 1 of this invention Explanatory drawing of the measurement result of the compression yield stress according to temperature of each resin in the embodiment Relationship diagram between PP pressure and recovery rate in the same embodiment Relationship diagram between primary heating and PP recovery rate in separation object in the embodiment Relationship between primary heating and PP purity in PP and PS separation objects Relationship between primary heating and PP recovery rate for PP and ABS separation objects Relationship between primary heating and PP purity in PP and ABS separation objects Relationship between secondary heating and PP and PS purity in PP and PS separation objects Relationship between secondary heating and PP recovery rate for PP and PS separation objects Relationship diagram of PP and PS separation strength with respect to secondary heating time in separation of separation object including PP and PS Infrared absorption characteristics of PP Infrared absorption characteristics of PS Characteristics of secondary heating means Relationship between the difference in heating time between the temperature at which PS and PP rise in temperature and the purity of PP and PS Process sectional drawing which shows the resin classification method of Embodiment 2 of this invention Relationship between primary heating and PP recovery rate for PP, PS and ABS separation objects Relationship between primary heating and PP purity in PP, PS, ABS separation objects Process sectional drawing which shows the resin classification method of Embodiment 3 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st resin 2 2nd resin 2a 2nd resin adhering by 1st heating pressurization 2b 2nd resin not adhering by 1st heating pressurization 3 Sorting member 4 Flat plate 5 Blade 6 1st Resin 7 Second resin 8 Third resin

Claims (14)

A separation object in which two or more kinds of resins having different glass transition temperatures and yield stresses are mixed is placed on a separation member and subjected to primary heating and pressurization, and the temperature of the primary heating at that time is set as the resin. The temperature is lower than the glass transition temperature of one or more types of resins and higher than the glass transition temperature of one or more types of resins, and the applied pressure at that time is higher than the temperature of the primary heating. Among the resins having a lower glass transition temperature, the resin is set to be equal to or higher than the compressive yield stress of the resin having the highest compressive yield stress, and the resin whose compressive yield stress at the temperature of the primary heating is lower than the applied pressure is the separating member. After releasing the pressurized pressure force, the resin not attached to the separation member or the resin having a small adhesion force is separated from the separation member,
Furthermore, the separation member to which the resin has adhered is subjected to secondary heating, and the temperature of the secondary heating at that time is lower than the melting point of the resin having a temperature higher than the temperature of the primary heating and the lowest melting point of the separation object. A resin separation method in which only the resin having a glass transition temperature lower than the primary heating temperature is attached to the separation member, and the resin attached to the separation member is separated from the separation member and separated. The primary heating temperature is
The temperature is set between a resin having the lowest glass transition temperature and a resin having the next lowest glass transition temperature among two or more kinds of resins having different glass transition temperatures and yield stresses. 1. The resin fractionation method according to 1. The primary heating temperature is
The temperature is set between a resin having the highest glass transition temperature and a resin having the next highest glass transition temperature among the two or more types of resins having different glass transition temperatures and yield stresses. 1. The resin fractionation method according to 1. The resin fractionation method according to any one of claims 1 to 3, wherein the pressure is a pressure equal to or greater than 1.2 times the compressive yield stress. The resin separation method according to any one of claims 1 to 4, wherein a difference in maximum thickness with respect to the minimum thickness of the resin in the pressurizing direction in which the object to be separated is placed on the separation member is within 5.5 mm. The resin separation method according to any one of claims 1 to 5, wherein the thickness of the resin in the pressurizing direction in which the separation object is placed on the separation member is in a range of 0.5 mm or more and 6.0 mm or less. The resin separation method according to any one of claims 1 to 5, wherein the thickness of the resin in the pressurizing direction in which the separation object is placed on the separation member is in a range of 1.0 mm or more and 6.0 mm or less. The resin separation method according to any one of claims 1 to 5, wherein the thickness of the resin in the pressurizing direction in which the separation object is placed on the separation member is in a range of 1.0 mm or more and 3.0 mm or less. The temperature rising rate of the resin having a glass transition temperature lower than the temperature of the primary heating in the secondary heating is smaller than the temperature rising rate of the resin having a glass transition temperature higher than the temperature of the primary heating. The resin fractionation method according to any one of claims 1 to 8. By making the temperature increase rate of the resin having a glass transition temperature lower than the temperature of the primary heating in the secondary heating smaller than the temperature increase rate of the resin having a glass transition temperature higher than the temperature of the primary heating. , The heat treatment time at the temperature rise reaching temperature of the resin having a glass transition temperature lower than the temperature of the primary heating is shorter than the resin having a glass transition temperature higher than the temperature of the primary heating by 5 seconds or more, The resin fractionation method according to any one of claims 1 to 8, wherein the temperature rise time of the resin having a glass transition temperature lower than the temperature of the primary heating is 60 seconds or less. The separation object includes at least one of polypropylene, polyethylene, polylactic acid, polyvinyl chloride, polystyrene, acrylonitrile styrene, acrylonitrile butadiene styrene, and polycarbonate, according to any one of claims 1 to 10. Resin separation method. The resin separation method according to any one of claims 1 to 10, wherein the separation object is made of polypropylene and at least one of polystyrene or acrylonitrile butadiene styrene. The temperature of the primary heating is set to 15 ° C. or higher and lower than the glass transition temperature of the resin species of all separation objects other than polypropylene,
The resin fractionation method according to claim 12, wherein the temperature of the secondary heating is set to 70 ° C. or more and 155 ° C. or less and higher than the temperature of the primary heating. The temperature of the primary heating is set to 15 ° C. or higher and lower than the glass transition temperature of the resin species of all separation objects other than polypropylene,
The resin fractionation method according to claim 12, wherein the temperature of the secondary heating is set to 100 ° C. or more and 155 ° C. or less and higher than the temperature of the primary heating.

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