CN101434112B - Method for separating resin - Google Patents

Abstract

The invention relates to the reuse of resin materials, and provides a high-purity separation method of resin materials that does not cause drainage and is not affected by the specific gravity and dielectric loss characteristics of the resin materials. In this method, objects to be separated from two or more resins having different glass transition temperatures (glass transition temperature: first resin 1<second resin 2) are placed on the separation member 3, and then the first resin 1 and the second resin are separated. The first resin 2 is heated at a temperature between the glass transition temperature of the second resin 2 and then pressurized, whereby the first resin 1 is attached. Then, by adding a heat process of the second heating at a temperature higher than the first heating temperature, the shape of the second resin 2 is restored, thereby detached and recovered, and the blade 5 etc. is used to keep it adhered to the separation member 3 The 1st resin 1 was stripped and recovered.

Description

Resin separation method

technical field

The present invention relates to a technique for separating resin from a separation object mixed with resin chips for recycling waste household electrical appliances.

Background technique

In recent years, mass production, mass consumption, and mass waste economic activities have caused global environmental problems such as the greenhouse effect and resource depletion. Under such circumstances, in order to build a recycling-oriented society, the Home Appliance Recycling Law was implemented in April 2013, and the recycling of used air conditioners, TV picture tubes, refrigerators, freezers, and washing machines has been made compulsory.

In the past, after useless home appliances were broken in home appliance recycling factories, different materials were separated and recovered by using magnetism, wind, vibration, etc., for recycling. Especially for metal materials, various materials such as iron, copper, and aluminum can be recovered with high purity by using a specific gravity separation device or a magnetic separation device, achieving a high recycling rate.

On the other hand, among resin materials, polypropylene with light specific gravity (hereinafter referred to as PP) can be separated from high specific gravity by wet specific gravity separation, and recovered with high purity. However, in the wet specific gravity separation, a large amount of drainage occurs and polystyrene (hereinafter referred to as PS) and acrylonitrile-butadiene-styrene (hereinafter referred to as ABS) with similar specific gravity cannot be separated have become major problems. In addition, in recent years, the demand for high-specific-gravity filler-filled polypropylene composite materials has also expanded, which was difficult to cope with conventional specific-gravity separation.

In the following patent document 1 and patent document 2, the isolation|separation method which considered the said problem concerning recycling of a resin material is proposed.

Patent Document 1 proposes a separation method using a difference in melting temperature between two types of resins to be separated. In this method, a pair of heat-resistant steel rotating surfaces are heated to an intermediate temperature between the melting temperatures of the two types of resins to be separated. The two types of resins to be separated pass through the gap between the heated rotating surfaces, and only the resin with a low melting temperature adheres to the heated rotating surfaces, whereby the two resins are separated.

In addition, Patent Document 2 proposes a different separation method utilizing a dielectric loss between resin materials. This method applies electromagnetic waves to the object to be separated that is mixed with two or more kinds of resins, and uses the difference in melting characteristics caused by the difference in heat generation characteristics of different resin materials to separate. With these methods, neither drainage nor Affected by the specific gravity of the resin material.

Patent Document 1: Japanese Patent Application Laid-Open No. 4-126822

Patent Document 2: Japanese Patent Laid-Open No. 2002-234031

Contents of the invention

However, in Patent Document 1, for low-polarity molecular substances such as PP and PS with low adhesion to other substances, the adhesion strength of the molten resin becomes unstable, and high-purity separation cannot be performed. In addition, if the low-melting-point resin and the high-melting-point resin pass through the gap of the heated sliding surface at the same time, unmelted high-melting-point resin adheres to the melted low-melting-point resin and cannot be separated.

In addition, in Patent Document 2, since resin materials having similar dielectric loss characteristics cannot be separated, high-purity recovery is very difficult.

The present invention solves the above existing problems, and its object is to provide a resin separation method that does not cause drainage and is not affected by the specific gravity and dielectric loss characteristics of the resin material.

The resin separation method according to claim 1 of the present invention is characterized in that the object to be separated, which is mixed with two or more types of resins with different glass transition temperatures and yield stresses, is placed on the separation member, heated for the first time, and pressurized at the same time. The temperature of the first heating at this time is set to a temperature lower than the glass transition temperature of one or more resins among the above-mentioned resins and higher than the glass transition temperature of one or more resins, and the pressing force at this time is set to Among the resins whose glass transition temperature is lower than the first heating temperature, the compressive yield stress of the resin with the highest compressive yield stress is set, and at least the resin whose glass transition temperature is lower than the first heating temperature is attached to the above-mentioned separation member. The resin that is not attached to the above-mentioned separation member or the resin with low adhesion is separated from the above-mentioned separation member, and the above-mentioned separation member to which the resin is attached is further heated for the second time, and the temperature of the second heating at this time is set to At a temperature higher than the first heating temperature and lower than the melting point of the resin with the lowest melting point among the above-mentioned separation objects, only the resin whose glass transition temperature is lower than the first heating temperature is attached to the above-mentioned separation member, and the resin attached to the above-mentioned separation The resin on the part is separated from the above-mentioned separation part to perform separation.

The resin separation method described in claim 2 of the present invention is as described in claim 1, characterized in that the temperature of the first heating is set at two or more resins having different glass transition temperatures and yield stresses, and the glass transition temperature The lowest glass transition temperature of the resin, and the temperature between the glass transition temperature of the resin whose glass transition temperature is second only to that of the resin.

The resin separation method described in claim 3 of the present invention is as described in claim 1, characterized in that the temperature of the first heating is set at two or more resins having different glass transition temperatures and yield stresses, and the glass transition temperature The highest glass transition temperature of the resin, and the temperature between the glass transition temperature of the resin whose glass transition temperature is second only to that of the resin.

The resin separation method according to claim 4 of the present invention is as described in claim 1, wherein the pressing force is 1.2 times or more the compressive yield stress of the resin to be recovered.

The resin separation method described in claim 5 of the present invention is as described in claim 1, wherein the difference between the minimum thickness and the maximum thickness of the resin in the pressurizing direction of the resin on which the object to be separated is placed on the separation member is 5.5 mm. within.

The resin separation method according to claim 6 of the present invention is as described in claim 1, wherein the thickness of the resin in which the object to be separated is placed on the separation member in the direction of pressure is in the range of 0.5 mm to 6.0 mm. Inside.

The resin separation method described in claim 7 of the present invention is as described in claim 1, wherein the thickness of the resin in the pressurizing direction of the object to be separated placed on the separation member is in the range of 1.0 mm to 6.0 mm. Inside.

The resin separation method according to claim 8 of the present invention is as described in claim 1, wherein the thickness of the resin in which the object to be separated is placed on the separation member in the pressurizing direction is in the range of 1.0 mm to 3.0 mm. Inside.

The resin separation method described in claim 9 of the present invention is as claimed in claim 1, characterized in that, in the second heating, the temperature rise rate of the resin whose glass transition temperature is lower than the first heating temperature is higher than the glass transition temperature. The temperature rise rate of the resin at the first heating temperature.

The resin separation method described in claim 10 of the present invention is as described in claim 1, characterized in that, in the second heating, by making the temperature rise rate of the resin whose glass transition temperature is lower than the first heating temperature be lower than the glass transition temperature The temperature rise rate of the resin higher than the first heating temperature, the heat treatment time at the temperature rise limit temperature of the resin whose glass transition temperature is lower than the first heating temperature is longer than that of the resin whose glass transition temperature is higher than the first heating temperature The heating time of the resin whose glass transition temperature is lower than the first heating temperature is shorter than 5 seconds or more is 60 seconds or less.

The resin separation method described in claim 11 of the present invention is as described in claim 1, wherein the object to be separated includes polypropylene, polyethylene, polylactic acid, polyvinyl chloride, polystyrene, acrylonitrile-styrene, propylene At least one of nitrile-butadiene-styrene and polycarbonate.

The resin separation method according to claim 12 of the present invention is as described in claim 1, wherein the object to be separated consists of polypropylene, and at least one of polystyrene or acrylonitrile-butadiene-styrene.

The resin separation method described in claim 13 of the present invention is as described in claim 1, wherein the object to be separated is composed of polypropylene, and at least one of polystyrene or acrylonitrile-butadiene-styrene, And the temperature of the first heating is set at a temperature of 15°C or higher and lower than the glass transition temperature of all resin species to be separated except polypropylene, and the temperature of the second heating is set at 70°C or higher and 155°C Below, and higher than the temperature of the first heating.

The resin separation method described in claim 14 of the present invention is as described in claim 1, wherein the object to be separated is composed of polypropylene, and at least one of polystyrene or acrylonitrile-butadiene-styrene, And the temperature of the first heating is set at a temperature of 15°C or higher and lower than the glass transition temperature of the resin species of all separation objects except polypropylene, and the temperature of the second heating is set at 100°C or higher and 155°C or lower , and higher than the first heating temperature.

According to this structure, by placing the separation target object of the resin whose thickness is within the set range on the separation member, and heating and pressing at a temperature between the glass transition temperature of the separation target resin, the separation member can be separated. , to separate the resin whose glass transition temperature is higher than the heating temperature, and the resin lower than the heating temperature. Thereby, the desired resin can be separated with high purity from the above-mentioned separation object which cannot be separated by conventional techniques.

Description of drawings

FIG. 1 is a cross-sectional view showing steps of a resin separation method according to Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram of the measurement results of the compressive yield stress of each resin according to temperature in the same embodiment.

Fig. 3 is a graph showing the relationship between the applied pressure and the recovery rate of PP in the same embodiment.

Fig. 4 is a graph showing the relationship between the first heating of the object to be separated and the recovery rate of PP in the same embodiment.

Fig. 5 is a graph showing the relationship between the first heating and the purity of PP for PP and PS separation objects.

Fig. 6 is a graph showing the relationship between the first heating and the recovery rate of PP for PP and ABS separation objects.

Fig. 7 is a graph showing the relationship between the first heating and the purity of PP for PP and ABS separation objects.

Fig. 8 is a graph showing the relationship between the second heating and the purity of PP and PS for PP and PS separation objects.

Fig. 9 is a graph showing the relationship between the second heating and the recovery rate of PP for PP and PS separation objects.

Fig. 10 is a graph showing the relationship between the second heating time and the adhesion strength between PP and PS and the separation member in the separation of the object to be separated including PP and PS.

Fig. 11 is a graph showing infrared absorption characteristics of PP.

Fig. 12 is a graph showing the infrared absorption characteristics of PS.

Fig. 13 is a characteristic diagram of the second heating method.

Fig. 14 is a graph showing the relationship between the difference in heating time between PS and PP at the heating limit temperature and the purity of PP and PS.

Fig. 15 is a cross-sectional view showing steps of a resin separation method according to Embodiment 2 of the present invention.

Fig. 16 is a graph showing the relationship between the first heating and the PP recovery rate for PP, PS, and ABS separation objects.

Fig. 17 is a graph showing the relationship between the first heating and the purity of PP for PP, PS, and ABS separation objects.

Fig. 18 is a cross-sectional view showing steps of a resin separation method according to Embodiment 3 of the present invention.

Detailed ways

Embodiment 1

1 to 14 show Embodiment 1 of the present invention.

1( a ) to FIG. 1( f ) show the process of separating the resin from the object to be separated in which two kinds of resins, the first resin 1 and the second resin 2 different in glass transition temperature and yield stress, are mixed.

In FIG. 1( a ), the separation target object described above 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. 1(b), the first heating is performed. The heating temperature at this 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 pressurized force is the same as or above the compressive yield stress of the first resin 1, and by heating and pressing the first resin 1 and the second resin 2 in this state, at least the first resin 1 Attached to the separation part 3. In other words, the first resin 1 at this time is plastically deformed and adheres to the separation member 3 because it is heated and pressurized under the conditions of not less than the glass transition temperature and not less than the compressive yield stress. In addition, when the pressure of the above-mentioned heating and pressing is above the compressive yield stress of the second resin 2, the second resin 2 will also deform in shape and adhere to the separation member 3, but the processing deformation is lower than that of the glass. Therefore, if a heat history higher than the first heating temperature is applied after the pressure is released, the shape returns to the state before the pressure is applied, and the separation member 3 is detached. In addition, when the pressing force of the above-mentioned heating and pressing 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, if the separator 3 is made of a metal mesh, punched metal, or other plate with irregularities on the surface, good adhesion strength can be obtained.

Next, as shown in Figure 1(c), by releasing the pressurized pressure, tilting the separation member 3, or slightly vibrating the separation member 3, the resin attached to the separation member 3 and the resin not attached to the separation member 3 can be separated. Resin on part 3. Here, the second resin 2 b that has not adhered to the separation member 3 detaches from the separation member 3 . The second resin 2 attached to the separation member 3 is denoted by 2a.

In addition, when the object to be separated contains a material (metal, paper, wood chip, thermosetting resin, etc.) that does not adhere to the separation member 3 under the heating and pressing conditions of FIG. As unadhered matter, it is separated and removed from the first resin 1 and the second resin 2a adhering to the separation member 3 .

Next, in FIG. 1( d ), the second heating is performed at a temperature higher than the first heating temperature and lower than the melting point of the resin with a lower melting point among the first resin 1 and the second resin 2 . As a result, the shape of the second resin 2a that has been adhering to the separation member 3 returns to the state before the pressurization, and becomes a state detached from the separation member 3 or a state in which the adhesion strength with the separation member 3 is significantly reduced. By tilting the separation member 3 or slightly vibrating the separation member 3, it is possible to separate from the first resin 1 adhering to the separation member 3 as shown in FIG. 1(e).

In addition, the above-mentioned first heating and second heating may be implemented by bringing the separating member 3 into contact with a hot plate, or a radiation method or a hot air method may be used without particular limitation.

Next, in FIG. 1( f ), the first resin 1 adhering to the separation member 3 can be recovered by scraping it off with a blade 5 or the like. At this time, if the modulus of elasticity of the first resin 1 is lowered by heating the first resin 1 for the third time, separation of the first resin 1 and the separation member 3 becomes easy.

Generally, when a resin material is heated, there is a temperature at which the rigidity rapidly decreases and the fluidity rapidly increases within a certain narrow temperature range from a hard, non-fluid state at a low temperature. The temperature causing such a change in physical properties is called the glass transition temperature.

Table 1 below shows the results of measuring the glass transition temperatures of PP, PE, PLA, PVC, PS, AS, ABS, and PC using a differential scanning calorimeter (model: DSC220) manufactured by Seiko Instruments Co., Ltd. A clear difference in glass transition temperature due to the difference in each resin was confirmed.

Table 1

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

When pressure is applied to the resin material and the pressure is raised to a range above the elastic limit of the resin material, the point (yield point) at which the displacement (strain) begins to increase rapidly corresponding to a slight increase in the pressure is reached. The pressurized force at which this point is reached is defined as the compressive yield stress.

Figure 2 is the result of measuring the compressive yield stress of each resin material in Table 1 as a function of temperature using a compressive stress tester (model: TCM10000 (compressive loading speed 1 mm/min)) manufactured by TOKYO SEIZOSHO Ltd. .

The compressive yield stress of each resin material decreases as the temperature increases, and when it reaches above the glass transition temperature, it reaches 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 each resin tends to undergo compression deformation under low applied pressure above the glass transition temperature.

Example 1

The method of separating the desired resin from the separation object containing PP and PS will be described.

Here, the first resin 1 is PP, and the second resin 2 is PS.

The separation part 3 and the object to be separated are loaded on the pressure plate of the plate press, and a 3.0mm spacer is sandwiched to achieve a predetermined thickness, and the pressure is applied for 60 seconds to further remove the resin below 1.0mm. The thickness in the pressing direction is made uniform within the range of not less than 1.0 mm and not more than 3.0 mm.

In addition, the compression method of using a roller press instead of a flat press can also homogenize the resin to the desired thickness. When using a roller press, regardless of the vertical or horizontal type, the thickness of the resin can be continuously uniformed. At this time, by optimizing and optimizing the roll gap (roll gap), the diameter of the roll, the number of rotations of the roll, and the number of rolls , can effectively implement uniformity of resin thickness.

The separation member 3 used a stainless steel mesh with a mesh opening of 0.28 mm, a wire diameter of 0.23 mm, and a size of 150 mm×150 mm.

Next, place the object to be separated on the separating member 3 at a ratio corresponding to 45% to 55% of the total area of the separating member 3 under the condition that the resins do not overlap each other, and load the separating member 3 in a hot press. The first heating was performed at 70° C. on a hot plate, and the heating and pressurization was performed at a pressure of 20,000 kgf for 30 seconds.

Next, the separation member 3 on which the object to be separated by heating and pressure is placed is mounted on a hot plate, and while the second heating is performed at 150° C. for 20 seconds, the separation member 3 is inclined to separate and recover the second type. Resin 2.

Next, the separation member 3 that has separated and removed the second resin 2 is mounted on the above-mentioned electric hot plate, and is heated for the third time at 150° C. for 30 seconds, and on the above-mentioned electric hot plate, a stainless steel blade with a thickness of 1 mm is used to remove the adhered The first resin 1 on the separation member 3 is scraped off, peeled off and recovered.

Qualitative analysis was performed on the resin separated in the second heating and the third heating using an infrared absorption spectrometer to confirm the quality of the resin separation. As a result, the resin detached by the second heating was PS with a purity of 100%, and the resin scraped off by the blade for the third heating was PP with a purity of 100%.

In addition, it is preferable to uniformize the particle size of the object to be separated by using a sieve before homogenizing to a predetermined thickness. First, use a sieve with a mesh size of 8.5 mm to remove coarse particles from the object to be separated, and then use a sieve with a mesh size of 1.0 mm to remove small mixed flakes and powder from the object to be separated, so that the particle size of the object to be separated can be uniformed to within a certain range.

In addition, it can be seen that the higher the heating temperature for the first time, the greater the adhesive strength of the resin, and the higher the heating temperature for the second and third times, the easier the peeling of the resin tends to be. However, if the object to be separated is heated at a temperature higher than the melting point of the resin, the resin will melt, so that adhesion and detachment cannot be completely performed, and efficient separation cannot be performed. Therefore, the heating temperature should not exceed the melting point of the resin with the lowest melting point among the above separation objects.

Next, the influences of the pressurization pressure during heating and pressurization, the temperature of the first and second heating, the thickness of the resin, and impurities that affect the quality of the above-mentioned resin separation will be described in order.

—Influence of pressurized pressure during heating and pressurization—

Fig. 3 is a diagram showing the relationship between the pressurized pressure and the PP recovery rate at the time of heating and pressurization in the separation of the separation object containing PP and PS. The horizontal axis represents the ratio of the compressive yield stress of PP at the temperature of the first heating to the pressure applied to the object to be separated at the temperature of the first heating. The PP recovery rate (%) on the vertical axis is the percentage (%) of the amount of PP recovered by the third heating with respect to the total amount of PP contained in the object to be separated.

As shown in FIG. 3 , it was found that the recovery rate of PP was improved when the pressurized pressure was increased. By increasing the applied pressure to a level above the compressive yield stress of PP, PP can be kept adhering to the separation member, and PP can be recovered from the object to be separated. In addition, it has been found that the pressurizing force of PP is preferably 1.2 times or more that when the recovery rate of PP is 100% relative to the compressive yield stress of PP.

The same verification was also carried out with resins other than PP listed in Table 1. As a result, any of the resins can be recovered under the condition of yield compressive stress or more, and high recovery can be obtained under the condition of 1.2 times or more of the yield compressive stress Rate.

In addition, since excessive pressure may cause damage to the separation part, increase the load on the equipment, and damage the resin, it is necessary to set the upper limit according to the separation part and equipment specifications.

- Influence of the first heating temperature -

Fig. 4 is a graph showing the relationship between the first heating temperature and the PP recovery rate in the separation of the separation object containing PP and PS. Fig. 5 is a graph showing the relationship between the first heating temperature and the purity of PP in the separation of the separation object containing PP and PS. The PP purity (%) on the vertical axis of Fig. 5 is the percentage (%) of the amount of PP recovered by the third heating relative to the total amount of resin recovered by the third heating.

The solid line in Fig. 4 is a curve obtained by heating and pressurizing for 30 seconds under a pressurizing pressure of 20,000 kgf. When the first heating temperature is 40° C. or lower, PP cannot be held on the separation member 3 because PP does not adhere to the separation member 3 , and separation and recovery cannot be performed. When the first heating temperature is in the range from 60°C to 90°C, the adhesion strength of PP increases, and the purity and recovery rate of PP can reach 100% through the operation of the second heating and the third heating .

In addition, the dotted line in Figure 4 is a curve obtained by heating and pressing for 30 seconds under a pressure of 40,000 kgf. Since the adhesion strength of PP increases above 15°C, the purity and recovery of PP can reach 100%. Under the condition of such a high pressure, PP can be separated in the low temperature region. However, if the pressure is raised above 40000kgf, the breakage of the separation part occurs.

In addition, as shown in Figure 5, if the temperature of the first heating is increased to 100°C or higher, since the temperature is higher than not only the glass transition temperature of PP, but also higher than the glass transition temperature of PS, it cannot be made by the second heating. The shape of PS recovers, and the purity of PP decreases.

From the above results, it is found that for the separation object containing PP and PS, the first heating must be carried out at a temperature of 15°C to 90°C, and it is more preferable to carry out the first heating at a temperature of 60°C to 90°C under a pressure of 20000kgf. secondary heating.

Fig. 6 is a graph showing the relationship between the first heating temperature and the PP recovery rate in the separation of the separation object containing PP and ABS. Fig. 7 is a graph showing the relationship between the first heating temperature and the purity of PP in the separation of the separation object containing PP and ABS.

As shown in FIG. 6 and FIG. 7 , the same tendency as the separation target objects including PP and PS was confirmed. As shown in FIG. 6 , when the temperature of the first heating is 40° C. or lower, PP cannot be adhered and held on the separation member 3 , and separation and recovery cannot be performed. When the temperature of the first heating is in the range from 60°C to 110°C, the adhesion strength of PP increases, and the purity and recovery rate of PP can reach 100% through the operation of the second heating and the third heating . In addition, the dotted line in Fig. 6 is a curve obtained by heating and pressing for 30 seconds under the condition of a pressure of 40000kgf. Since the adhesion strength of PP increases above 15°C, the purity and recovery of PP can reach 100%.

In addition, as shown in Figure 7, if the temperature of the first heating is increased to 120°C or higher, the temperature is higher than the glass transition temperature of not only PP but also ABS, so the shape of ABS cannot be restored by the second heating , the purity of PP decreased.

From the above results, it is found that for the separation object containing PP and ABS, the first heating must be carried out at a temperature of 15°C to 110°C, and it is more preferable to carry out the first heating at a temperature of 60°C to 110°C under a pressure of 20000kgf. secondary heating.

—Influence of the second heating temperature—

Fig. 8 is a graph showing the relationship between the second heating temperature and the purity of PP and PS in the separation of the separation object containing PP and PS. Fig. 9 is a graph showing the relationship between the second heating temperature and the PP recovery rate in the separation of the separation object containing PP and PS.

The PS purity (%) on the vertical axis of FIG. 8 is the percentage (%) of the amount of PS desorbed and recovered by the second heating relative to the total amount of resin desorbed and recovered by the second heating. On the other hand, the PP purity (%) on the vertical axis of Fig. 8 is the PP recovered by the third heating relative to the total amount of resin separated and recovered by the third heating after the second heating at the set temperature. percentage of volume.

As shown in Figure 8, when the temperature of the second heating is lower than 70°C, since the temperature of the second heating is lower than that of the first heating, the shape of the PS will not return to the shape before pressing, so the PS does not change from The separating part 3 is detached, and PP and PS cannot be effectively separated. If the temperature of the second heating is raised to 70° C. or higher, the shape of the PS starts to recover, so that the PS is detached from the separation member, and the separation of PP and PS can be performed.

When the temperature of the second heating ranges from 100° C. to 155° C. for 20 seconds, the purity of PP can be made 100%. In addition, as shown in FIG. 9 , if the temperature of the second heating is increased to 155° C. or higher, since PP is melted and welded to the separation member 3 , the recovery rate of PP decreases.

The same verification was also carried out with resins other than PP listed in Table 1. As a result, the second heating (Japanese: 2nd heating, should refer to the second heating according to the context) must be lower than the lowest melting point of the object to be separated. The melting point of the resin and at a temperature higher than the first heating temperature.

From the above results, it was found that for the separation object containing PP and PS, the separation object containing PP and ABS, and the separation object containing PP, PS, and ABS, it is necessary to set the temperature at 70°C to 155°C, and The second heating is performed at a temperature higher than the first heating temperature, and it is preferable to perform the second heating at a temperature higher than the first heating temperature at a temperature of 100°C to 155°C.

—Effect of Resin Thickness—

When the shape of the object to be separated has a large variation, pressure variation occurs during pressurization and good adhesion cannot be obtained. Therefore, it is preferable to uniformize the thickness of the object to be separated in advance. It was found that if the difference between the maximum thickness of the resin and the minimum thickness of the resin in the thickness in the pressing direction is within 5.5 mm, the pressure is applied substantially uniformly and good adhesion can be obtained.

To study the effect of thickness, the adjustment of thickness was carried out by a plate press using a backing plate. Table 2 below shows the measurement results of the purity and recovery of PP and PS with respect to the thickness range of the object to be separated in the pressurizing direction.

Table 2

The separation part 3 and the object to be separated are loaded on the pressure plate of the plate press, and a 6.0mm backing plate is sandwiched to achieve a predetermined thickness, and the pressure is applied for 60 seconds to further remove less than 0.5mm of resin, thereby making the pressure The thickness in the direction is uniformed within the range of 0.5 mm to 6.0 mm, and the difference between the maximum thickness and the minimum thickness is adjusted within 5.5 mm. At this time, the purity of PS is 90% or more, and it is preferable to combine it with other resin separation methods, and most manufacturers of resin materials can regenerate the resin.

Similarly, if the thickness of the above-mentioned resin is uniformized to a range of 1.0mm to 6.0mm by adjusting the thickness with a backing plate, etc., the PS purity will reach 98% or more, which can be directly used as a recycled material. The purity of the material manufacturers regenerate, so this method is better.

Furthermore, if the thickness of the above-mentioned resin is uniformized in the range of 1.0 mm to 3.0 mm, the purity and recovery rate of PP and PS will reach 100%, so this method is more preferable.

The same verification was carried out with other resins listed in Table 1. As a result, it was confirmed that the same phenomenon as PP and PS resins also existed in other resins.

—Influence of the heating rate of the second heating—

Fig. 10 shows the relationship between the second heating time and the adhesion strength between PP and PS and the separation member in the separation of the object to be separated including PP and PS. The object to be separated is used after the thickness in the pressurizing direction is uniformized within the range of 0.5 mm to 6.0 mm. The adhesion strength of PP and PS is the value of the shear stress in the horizontal direction between the separation member measured using force gauge FGP-20 manufactured by NIDEC-SHIMPO CORPORATION. In addition, in order to easily detach the object to be separated from the separation member by tilting, micro-vibration, etc., the adhesion strength is preferably zero. In addition, in order to maintain the object to be separated stably attached to the separation member, the adhesion strength is preferably 2N or higher. That is, in the separation of separation objects including PP and PS, good separation results can be obtained if the adhesion strength of PS is zero after the second heating and the adhesion strength of PP is 2N or more.

As shown in Figure 10, it can be seen that the adhesion strength of PS decreases with the increase of the second heating time, and the adhesion strength of PS is zero when the second heating time is longer than 20 seconds. Regarding the adhesive strength of PP, it was confirmed that the adhesive strength of PP having a thickness of 1 mm or more did not decrease. However, for PP with a thickness of less than 1mm, it can be seen that as the second heating time increases, the adhesion strength decreases. If the second heating time is more than 20 seconds, there is PP with an adhesion strength less than 2N, which becomes PS. The reasons for the low purity and low recovery of PP.

Therefore, as a result of research on how to suppress the decrease in the adhesive strength of PP with a thickness of less than 1 mm, it was found that by making the temperature increase rate of PP in the second heating smaller than that of PS, the second heating time of PP can be substantially shortened. The ground shortening is a method of suppressing the reduction of the adhesion strength of PP in the second heating.

The control of the temperature rise rate of PP and PS can be easily implemented by utilizing the difference in the infrared absorption characteristics of the resins. Figures 11 and 12 show the infrared absorption curves of PP and PS. When irradiated with infrared rays in the 500-1200cm- ¹ wavenumber band that PP does not absorb and only PS absorbs, PS will be heated preferentially. In addition, in fact, PP and PS were simultaneously heated using a germanium-based infrared filter and a near-infrared panel heater having the characteristics shown in Fig. smaller.

Table 3 is the second heating in the separation of the separation object containing PP and PS by using the above-mentioned germanium-based infrared color filter and near-infrared flat heater, thereby reducing the heating rate of PP, and at the heating limit temperature ( The measurement results of the purity and recovery of PP and PS when the actual heating time at 150°C) is 5 seconds shorter than that of PS, and the results of the second heating with a hot plate are also described for comparison. From Table 3, it can be confirmed that the purity and recovery of PP and PS can be improved by shortening the heating time of PP.

table 3

Fig. 14 is a graph showing the relationship between the difference in heating time between PS and PP at the heating limit temperature and the purity of PP and PS. It is found that by shortening the heating time of PP by more than 5 seconds, the purity of PS resin can reach more than 98%, reaching the purity that can be directly used as a recycled material and regenerated by the resin material manufacturer. However, if the time for PP to reach the temperature rise limit temperature, that is, the temperature rise time exceeds 60 seconds, PP with an adhesion strength of 2N or less after the second heating will start to appear. Therefore, it is preferable that the heating time of PP is shorter than that of PS by more than 5 seconds. And the heating time is below 60 seconds.

Embodiment 2

15 to 17 show Embodiment 2 of the present invention.

Fig. 15(a) ~ Fig. 15(f) show that from the separation objects mixed with the first kind of resin 6, the second kind of resin 7 and the third kind of resin 8 with different glass transition temperature and yield stress, the separation Resin process.

In FIG. 15( a ), the object to be separated is placed on the separating 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. 15(b), the first heating is performed. The heating temperature at this time is not less than the glass transition temperature of the first resin 6 and 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 pressurized force is the same as or higher than the compressive yield stress of the first resin 6, and by heating and pressing the first resin 6, the second resin 7, and the third resin 8 in this state, at least The first resin 6 is attached to the separation member 3 .

In addition, although the second resin 7 and the third resin 8 are deformed in shape when the pressure of the above-mentioned heating and pressing is equal to or higher than the compressive yield stress of the second resin 7 and the third resin 8, Attached to the separation member 3, but since the processing deformation is carried out at a temperature lower than the glass transition temperature, if a heat history higher than the first heating temperature is applied after the pressure is released, the shape returns to the state before the pressurization, Detach from the separation part 3.

When the heating and pressing pressure is lower 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. 15(c), if the pressurized pressure is released, when the second resin 7 and the third resin 8 are not attached to the separation member 3, for the same reason as in Embodiment 1, by using The separation member 3 can be separated from the first resin 6 adhering to the separation member 3 by methods such as tilting the separation member 3 or slightly vibrating the separation member 3 .

In Fig. 15(d), the second heating is carried out at a temperature higher than the first heating temperature and lower than the melting point of the first resin 6, the second resin 7 and the third resin 8 with a lower melting point. After the second heating, the shapes of the second resin 7 and the third resin 8 return to the state before pressurization, and become a state of not adhering to the separation member 3 or a state in which the adhesion strength is significantly reduced. Therefore, by making the separation member 3 Tilting or micro-vibration, etc., can be separated from the first resin 6 as shown in Fig. 15(e).

The first resin 6 remaining attached to the separating member 3 can be recovered by scraping it off with a blade 5 or the like as shown in FIG. 15(f). At this time, if the modulus of elasticity of the first resin 6 is lowered by heating the first resin 6 for the third time, separation of the first resin 6 and the separation member 3 becomes easy.

It was found that when three kinds of resins having different glass transition temperatures and yield stresses are mixed together, it is preferable to keep the resins with lower glass transition temperatures adhering to the separation member 3 in order to make them highly purified. Methods. In addition, the second resin 7 and the third resin 8 separated from the separation member 3 can be separated by repeating the same operation.

Figure 16 shows the relationship between the first heating temperature and the PP recovery rate in the separation of a resin mixture containing PP, PS, and ABS. Fig. 17 shows the relationship between the first heating temperature and the purity of PP in the separation of a resin mixture containing PP, PS, and ABS.

As shown in FIG. 16, when the temperature of the first heating is below 40°C, since PP is not attached to the separation member 3, it is impossible to keep PP adhered to the separation member 3, and separation and recovery cannot be performed. When the temperature of the first heating is in the range of 60°C to 90°C, the purity and recovery rate of PP can reach 100% by performing the subsequent second and third heating operations. In addition, the dotted line in Fig. 16 is a curve obtained by heating and pressing at a pressure of 40,000 kgf for 30 seconds. Since the adhesion strength of PP increases above 15°C, the purity and recovery of PP can reach 100%.

In addition, as shown in Figure 17, if the temperature of the first heating is increased to 100°C or higher, since this temperature is higher than the glass transition temperature of not only PP but also PS, it cannot be made by the second heating. The shape of PS is restored and cannot be peeled off.

From the above results, it is found that for the separation object containing PP, PS and ABS, the first heating must be carried out at a temperature of 15°C to 90°C, more preferably at a temperature of 60°C to 90°C under a pressure of 20000kgf 1st heating.

Embodiment 3

Fig. 18 shows Embodiment 3 of the present invention.

Fig. 18(a) to Fig. 18(f) are the same as Embodiment 2, showing the mixture of the first resin 6, the second resin 7 and the third resin 8 with different glass transition temperatures and yield stresses. Among the objects to be separated, the process of separating the resin.

In FIG. 18( a ), the object to be separated is placed on the separating 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. 18(b), the first heating is performed. The heating temperature at this time is not less than the glass transition temperature of the first resin 6 and the second resin 7 and 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 pressurized force is the same as or higher than the compressive yield stress of the resin having a higher compressive yield stress among the first resin 6 and the second resin 7. In this state, the first resin 6, the second resin The two types of resin 7 and the third type of resin 8 are heated and pressurized to attach at least the first type of resin 6 and the second type of resin 7 to the separation member 3 . In other words, the first kind of resin 6 and the second kind of resin 7 at this time, because the glass transition temperature of the first kind of resin 6 and the second kind of resin 7 is higher than the glass transition temperature of the first kind of resin 6 and the second kind of resin 7 When heated and pressurized under the conditions of compressive yield stress or higher, plastic deformation occurs and adheres to the separation member 3 .

Although when the pressing force of the above-mentioned heating and pressing is above the compressive yield stress of the third resin 8, the third resin 8 will also deform in shape and adhere to the above-mentioned separation member 3, but due to the processing deformation, it is lower than the vitrification. Therefore, if a heat history higher than the first heating temperature is applied after the pressure is released, the shape returns to the state before the pressure is applied, and the separation member 3 is detached.

The third resin 8 does not adhere to the separation member 3 when the pressure applied by heating and pressing is lower than the compressive yield stress of the third resin 8 .

Next, as shown in FIG. 18(c), if the above-mentioned pressurized pressure is released, when the third resin 8 does not adhere to the separation member 3, for the same reason as in Embodiment 1, by tilting or micro-vibration, etc., Can be separated from the resin attached to the separation member 3.

Next, in Fig. 18(d), the second heating is performed. The temperature at this time is higher than the first heating temperature and lower than the melting point of the resin with the lowest 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 returns to the state before the pressurization, and it becomes a state where it does not adhere to the separation member 3 or a state where the adhesion strength is significantly reduced. , can be separated from the first resin 6 and the second resin 7 as shown in FIG. 18( e ).

The first resin 6 and the second resin 7 remaining attached to the separation member 3 can be recovered by scraping off with a blade 5 or the like as shown in FIG. 18( f ). At this time, if the modulus of elasticity of the first resin 6 and the second resin 7 is reduced by heating the first resin 6 and the second resin 7 for the third time, the first resin 6 and the second resin Separation of the resin 7 and the separation member 3 becomes easy.

It was found that when three kinds of resins having different glass transition temperatures and yield stresses are mixed together, it is preferable to sequentially detach the resin with higher glass transition temperature from the separation member 3 to make it highly purified. In addition, 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 when the object to be separated contains impurities other than the desired resin, the desired resin can be similarly separated from the object to be separated by utilizing the difference in glass transition temperature and yield stress.

When rubber, adhesive tape, and low-melting point resin are included in the impurity components, among the above-mentioned impurities adhered by heating and pressure, there are impurities that are not detached in the second heating, and some of the above-mentioned impurities are scraped off with a blade and peeled off for recovery. In the desired resin, the purity of the desired resin decreased. In addition, when impurities having a glass transition temperature higher than the first heating temperature are contained in the impurity components, since the shape of a part of the above-mentioned impurities is restored to the state before pressurization by the second heating, the second heating The purity of the recovered resin decreases. In addition, metals are contained in the composition of impurities. In the case of wood, paper, etc., since the above impurities do not adhere to the separation member, the desired resin can be separated.

When impurities are contained in the object to be separated, the purity of the desired resin may vary depending on the type and content of the impurities, but the desired resin can also be separated. Therefore, even if some impurities are mixed in the process of the present invention, the desired resin can be separated.

The verification experiment of the high-purity separation of PP according to the present invention was carried out by using as a sample the crushed plastic separation object of waste household appliances containing PP, PS, ABS and impurities. The above samples are refrigerators made of waste household appliances. Firstly, the compressor and the internal parts containing high-purity resin parts are removed by manual sorting, and then crushed with a pulverizer, and further separated by wind force, magnetic force, and electrostatic separation. and other processes to remove metals and other debris with a maximum particle size of about 10.0mm.

A part of the above-mentioned sample is taken out in advance, and the PP and impurity content in the above-mentioned sample is analyzed by well-known infrared absorption analysis, specific gravity analysis, visual inspection and palpation, and then the separation of PP is carried out. Table 4 below shows the measurement results of the PP content (%) in the above samples, the impurity content (%) in the above samples, and the purity (%) of PP recovered by peeling.

Table 4

PP content (%) Impurities (%) PP purity (%) 38.6 2.3 99.1 38.6 1.1 99.6 38.6 0.5 99.9

From Table 4, it was verified that even in the case of contamination of impurities, the purity that can be regenerated as a recycled material can be maintained.

It can be seen that the present invention is particularly effective for the separation of PP, PS and ABS, which are particularly abundant in waste household appliances. It is also effective for filling resins with fillers that cannot be separated in the past, such as specific gravity separation, and PLA, which will increase in demand in the future.

The separation method of the object to be separated using the difference in glass transition temperature of the present invention can be used as a separation method for recycling specific resin materials from resin mixed chips contained in waste household appliances or general waste, and can be used for the separation of resins. Resource recycling.

Claims (13)

1. The resin separation method is characterized in that, the separation target object mixed with two or more resins with different glass transition temperatures and yield stresses is placed on the separation member and heated for the first time, while pressurizing, and the first time at this time is The temperature of primary heating is set to a temperature lower than the glass transition temperature of one or more resins in the resin and higher than the glass transition temperature of one or more resins, and the pressing force at this time is set at the glass transition temperature. Of the resins whose temperature is lower than the first heating temperature, the compressive yield stress of the resin with the highest compressive yield stress is greater than or equal to that of the resin whose glass transition temperature is lower than the first heating temperature. The resin on the separation member or the resin with low adhesion is separated from the separation member, and the separation member to which the resin is attached is further heated for the second time, and the temperature of the second heating at this time is set to At a temperature higher than the first heating temperature and lower than the melting point of the resin with the lowest melting point among the objects to be separated, only the resin whose glass transition temperature is lower than the first heating temperature is attached to the separation member, and the separating the resin on the separation member from the separation member to perform separation; The aforementioned object to be separated includes at least one of polypropylene, polyethylene, polylactic acid, polyvinyl chloride, polystyrene, acrylonitrile-styrene, acrylonitrile-butadiene-styrene, and polycarbonate. 2. The resin separation method according to claim 1, wherein the temperature of the first heating is set at the temperature of the resin with the lowest glass transition temperature among the two or more resins having different glass transition temperatures and yield stresses. The glass transition temperature, and the temperature between the glass transition temperature of the resin whose glass transition temperature is as low as that of the resin. 3. The resin separation method according to claim 1, wherein the temperature of the first heating is set at the temperature of the resin with the highest glass transition temperature among the two or more resins having different glass transition temperatures and yield stresses. The glass transition temperature, and the temperature between the glass transition temperature of the resin whose glass transition temperature is second only to the resin. 4. The resin separation method according to claim 1, wherein the applied pressure is 1.2 times or more the compressive yield stress of the resin to be recovered. 5. The resin separation method according to claim 1, wherein the difference between the minimum thickness and the maximum thickness in the pressurizing direction of the resin on which the object to be separated is placed on the separation member is within 5.5 mm. 6. The resin separation method according to claim 1, wherein the thickness of the resin in the pressurizing direction of the object to be separated placed on the separation member is in the range of 0.5 mm to 6.0 mm. 7 . The resin separation method according to claim 1 , wherein the thickness of the resin in which the object to be separated is placed on the separation member in the pressurizing direction is in the range of 1.0 mm to 6.0 mm. 8. The resin separation method according to claim 1, wherein the thickness of the resin in which the object to be separated is placed on the separation member in the pressurizing direction is in the range of 1.0 mm to 3.0 mm. 9. The resin separation method according to claim 1, characterized in that, in the second heating, the temperature rise rate of the resin whose glass transition temperature is lower than the first heating temperature is less than the glass transition temperature higher than the first heating Temperature The rate at which the resin heats up. 10. The resin separation method according to claim 1, characterized in that, in the second heating, the temperature rise rate of the resin whose glass transition temperature is lower than the first heating temperature is lower than the glass transition temperature higher than the first time The heating rate of the resin at the heating temperature is such that the heat treatment time of the resin whose glass transition temperature is lower than the first heating temperature at the heating limit temperature is 5 seconds shorter than that of the resin whose glass transition temperature is higher than the first heating temperature Above, and the temperature rise time of the resin whose glass transition temperature is lower than the first heating temperature is 60 seconds or less. 11. The resin separation method according to claim 1, wherein the object to be separated consists of polypropylene, and at least one of polystyrene and acrylonitrile-butadiene-styrene. 12. The resin separation method according to claim 1, wherein the object to be separated is composed of at least one of polypropylene and polystyrene or acrylonitrile-butadiene-styrene, and the first time The heating temperature is set at a temperature of 15°C or higher and lower than the glass transition temperature of all resin species to be separated except polypropylene, and the temperature of the second heating is set at a temperature of 70°C to 155°C and higher than The temperature of the first heating. 13. The resin separation method according to claim 1, wherein the object to be separated is composed of at least one of polypropylene and polystyrene or acrylonitrile-butadiene-styrene, and the first The heating temperature is set at a temperature of 15°C or higher and lower than the glass transition temperature of all resin species to be separated except polypropylene, and the temperature of the second heating is set at a temperature of 100°C to 155°C and higher than The temperature of the first heating.

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