JP2001079917A - Method for modifying and molding crushed flakes of recovered pet bottle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a molded article of PET low in cost, high in value added and good in capacity by recycling a recovered PET bottle. SOLUTION: A recovered PET bottle of which the outer surface is washed with high pressure hot water is crushed into flakes and washed while rubbed by a water injection type crusher by a twin-screw conveyor to gravitationally separate the foreign matter bonded to the flakes and dehydrated by a hot air vacuum dryer to produce dry PET bottle flakes with a water content of 100 ppm or less. A compsn. comprising these PET bottle flakes or a mixture consisting of 100-60 pts.wt. of PET bottle flakes and 0-40 pts.wt. of a polyethylene terephthalate resin with an intrinsic viscosity IV value of 1.0 or less and a water content of 100 ppm or less and 0.001-10 pts.wt. of a carbodiimide compd. is mixed in an airtight state to obtain a compd. which is, in turn, directly molded to produce a molded article enhanced in mechanical strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the extrusion molding of PET pipes having improved moldability and mechanical strength by adding a carbodiimide compound for material recycling of recovered PET bottles (component, polyethylene terephthalate resin). The present invention provides molding technology, and has succeeded in developing a technology for producing an amorphous PET molded product by high-value-added molding using a collected PET bottle.

[0002]

2. Description of the Related Art In recent years, the use of collected PET bottles has become a major problem both in Japan and overseas, but there is no new value-added processing technology for recycling collected PET bottles. As of 1998, 600,000 t /
y, 1.5 million t / y in North America, 1 million t / y in EU, and more than 4 million t / y plastic bottles worldwide,
Reduction to raw materials is mainly performed by chemical recycling. In Japan, material recycling is mainly reused only in discount clothing (eg, shirts), carpets, and the like, often in small amounts in blends with pet resin.

An object of the present invention is to provide a molded article of high quality with high added value, mainly using a collected PET bottle, focusing on a pet resin which is friendly to the global environment and has good physical properties. And

[0004] Conventional pet resins (polyethylene terephthalate resins) are used for fibers, drawn films and drawn blow bottles which are crystallized by drawing orientation to improve physical properties such as mechanical strength. With respect to these PET resin crystallized molded products, molding such as extrusion of amorphous molded products has not been successfully developed at all up to now due to the difficulty of the processing technology.

A mixture for maintaining strength in pelletization in which a carbodiimide compound is blended with a polyester resin is proposed in JP-A-11-34048, and the strength of the recovered pet resin is improved by recovering the tensile strength to the same level as that of the virgin resin. How to maintain is described. However, there is no mention of moisture deterioration of the pet resin.

In the present invention, the present invention has been completed by focusing on the fact that pet resin is degraded by moisture and clarifying the countermeasures.

That is, since the pet resin contains an ester bond, hydrolysis by moisture occurs very easily, and the molecular weight is reduced and the strength is reduced. Without consideration and conditions for moisture in the pet resin, the fact that resin degradation due to moisture has a greater effect than the effect of adding the carbodiimide compound occurs.

Further, in the present invention, in order to prevent more severe hydrolysis and thermal decomposition of the recovered PET bottle crushed flakes at a high processing temperature, the extruder is prepared by directly compounding the flakes directly without passing through pellets as a forming raw material. The aim is to improve the quality by charging the molding machines such as and avoiding the heat history as much as possible. This contributes to improvement in not only the production cost but also the melt viscosity of the resin, moldability such as extrusion moldability, and mechanical strength. The present invention is fundamentally different from the method of the above publication in these two points.

[0009]

DISCLOSURE OF THE INVENTION The present invention relates to a method for manufacturing a pulverized recovered PET bottle by using a chain extender carbodiimide compound to improve the moldability of extrusion and the like and the mechanical strength of the molded product while keeping the manufacturing cost as low as possible. To provide a new processing technology.

The present invention focuses on an environmentally friendly pet resin having good physical properties, and aims to recycle a collected PET bottle, which is a problem at present. The purpose is to provide the market.

[0011] PET resin of PET bottle grade is
Its intrinsic viscosity IV value is 1.0 or less, for example, 0.7 to 0.1.
A low molecular weight grade such as 8 is used for low cost and the like, and the resin component of the PET bottle is further reduced in molecular weight by hydrolysis by moisture and thermal decomposition by high temperature in the stretch blow molding. For this reason, the recovered PET bottle crushed flakes are too difficult to mold, such as by extrusion, because the melt viscosity is too low, and the mechanical strength of the molded products is extremely poor. Recycling has not been successful so far.

In the present invention, a carbodiimide compound as a chain extender is reacted with a recovered PET bottle as a main raw material and a PET resin having an IV value of 1.0 or less, to increase the molecular weight and increase the melt viscosity thereof, and to extrude the resin. An object of the present invention is to provide a technique which enables molding such as molding and at the same time improves the mechanical strength of a molded article.

The following four points can be cited as basic items of the technical problem of the present invention. (1) Foreign substances (mud, dust,
Cleaning is effective at low cost so that removal of labels, caps, etc.) does not hinder molding operations such as extrusion molding. (2) PET resin has a strong hygroscopic property, and it is very easily hydrolyzed at a high molding temperature due to the water content, thereby preventing the pet resin from being reduced in molecular weight and degraded. (3) The crushed PET bottle flakes having a low molecular weight and deteriorated are polymerized and reformed in high yield. (4) To provide a low-cost molded product such as an extruded product with high added value in order to commercialize and spread the present invention. The present invention has solved these problems, and means for solving each of the problems will be described later in detail.

[0014]

SUMMARY OF THE INVENTION According to the present invention, a recovered PET bottle is washed with high-pressure hot water on the outer surface of the bottle, crushed and washed with a water-injection crusher to form flakes. While rinsing, the attached foreign substances were separated by specific gravity, and further dehumidified to 100 ppm or less of moisture with hot air and a vacuum drier to produce dried flakes, and 100 to 60 parts by weight of the PET bottle flakes and an intrinsic viscosity IV value of 1. PET bottle flake alone or mixture with 0 to 40 parts by weight of polyethylene terephthalate resin dehumidified to 0 or less and water of 100 ppm or less, and a composition obtained by airtightly mixing a composition of 0.001 to 10 parts by weight of a carbodiimide compound Is directly molded to produce a molded article having improved mechanical strength.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a collected PET bottle is used as a raw material. However, not only the collected PET bottle alone but also a mixture with a PET resin, that is, 100 to 60 parts by weight of dried and dehumidified flakes of the collected PET bottle. Intrinsic viscosity I
A mixture with 0 to 40 parts by weight of a polyethylene terephthalate resin having a V value of 1.0 or less and a moisture content of 100 ppm or less is also used as a raw material.

First, means for solving the above-mentioned four problems will be described sequentially and concretely.

(1) Cleaning of Foreign Substances Attached to Collected PET Bottles In molding such as continuous extrusion molding, if foreign substances such as mud, dust, labels, caps, etc. are mixed, the quality of molded products and the molding operation are hindered. In the case of an extruder, it is generally considered that foreign substances are removed by a screen changer, but in actuality, in extruding crushed flakes, the flakes at the supply section in the extruder are solid phase, and the compression section, dalmage From the part to the die, the liquid phase has a low viscosity, and in the sizing die, the liquid phase is converted again to the solid phase. Due to the large difference in the shear rate of the resin in these three phases during transport of the compound in the molding machine, the flow is disturbed, and surging and flow marks are liable to occur. Therefore, since the flow tends to be turbulent due to the screen change operation of the screen changer located at the breaker plate portion, the screen changer must be avoided as much as possible. Therefore, thorough removal of foreign substances such as mud in flakes is an important means for the cost and quality of molded articles.

Specifically, this cleaning method is preferably performed in the following steps. As a first step, the collected PET bottles are washed with high-pressure hot water by a shower nozzle while being transported by a mesh conveyor to wash off mud and dust on the outer surface of the bottles. In the second step, the crushed pieces are poured out from the upper part of the water tank by specific gravity separation while the flakes are washed while crushing while pouring water, and the mud and the like are poured out from the lower part of the water tank. As the third stage,
The milled flakes are dewatered with a dehydrator at an efficiency of 95%. As a fourth step, the wet flakes are charged from the low side of the rectangular inclined water tank and washed again with the inwardly rotating twin screw conveyor while being transported to the high side while mud or the like is moved downward. The remaining label, crushed pieces of the cap, etc. are poured upward.

In the molding of the present invention, the use of the crushed flakes having a high degree of cleaning and the low-cost cleaning step contributes to the low cost and high quality of the molded article.

(2) Removal of Moisture Contained in PET Bottle Grinding Flakes In drying the collected PET bottle grinding flakes, the moisture is dehumidified to 100 ppm or less by hot air and a vacuum dryer. Specifically, the following steps are performed. Is preferred. First,
Put in a continuous rotary dryer type hot air dryer, for example, dry at 150 ° C. for a retention time of, for example, 2 hours, and then transfer to a vacuum dryer to dry at a required degree of vacuum of 10 ⁻² TORR, for example, for 3 hours. And dehumidify to a water content of 100 ppm or less.
The crushed flakes dehumidified to pm or less are stored in an airtight storage tank with a nitrogen stream, and transferred to a hopper dryer on an extruder.

(3) Influence of moisture on crushed PET bottle flakes and PET resin The crushed PET bottle flakes and PET resin have an ester bond in the main chain, and the general structure of PET resin (polyethylene terephthalate resin) is as follows. formula

[0022]

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## EQU1 ## Therefore, hydrolysis by water easily proceeds. In particular, the extrusion molding temperature of 260 to 270
At a high temperature such as ° C., hydrolysis is accelerated and thermal decomposition also occurs. That is, the hydrolysis reaction between the pet resin and water produces -OH groups and -COOH groups at the molecular terminals of the pet resin, and the thermal decomposition reaction of the pet resin produces -COOH groups at the molecular terminals.

The reduction of the molecular weight IV value due to hydrolysis of the pet resin is very severe and is as follows. This table is quoted from Mitsubishi Rayon "Diamond Night Catalog".

[0025]

[Table 1]

This table shows the rate of decrease when the hydrolysis reaction rate is 100%.
It must be considered that the high temperature of ° C. strongly promotes the hydrolysis and lowers the IV value at a high conversion. Since the reduction of the IV value due to the hydrolysis is the essence and fate of the pet resin, the main point of the present invention is a means for improving the mechanical strength of the molded article, that is, dehumidifying so that the effect of the carbodiimide compound is not diminished by moisture. Must.

(Experiment-1) Speed of moisture absorption of the dried flaked flakes from the collected PET bottle. The speed of hygroscopicity of the recovered crushed PET bottle flakes was measured. As a moisture measuring device for the ground flakes, a dry type moisture meter CZA-2000 manufactured by Chino Co., Ltd. was used, and the measurement temperature was 150 ° C.
All measurements were performed on a sunny day.

[0028]

[Table 2]

As is clear from the measured values, the ground flakes absorb moisture in a very short time. As is apparent from the reduction rate of the IV value in Table 1, the problem of molecular weight reduction due to moisture cannot be avoided particularly in the discussion of the physical properties and mechanical strength of the crushed PET bottle flakes.

(4) Effect of Chain Extender Carbodiimide Compound Reacting at Terminal of PET Resin Molecules The crushed flakes of the collected PET bottles have an original resin grade of less than 1.0 due to bottle cost and the like.
It is considered that the molecular weight of the flakes is considerably reduced due to the deterioration during the molding of the bottle.

Since the extrusion temperature is as high as 260 to 280 ° C., the melt viscosity of the flake is very low, so that the moldability is a major problem. In addition, the mechanical strength of the molded product is very brittle, and the molded product is extremely broken like a thin-walled glass, which is not practical. Therefore, it is absolutely necessary to take measures to increase the molecular weight in recycling the collected PET bottles. Therefore, the present inventor next experimented on the effect of the cross-linking agent by a conventional method as comparison data with the carbodiimide compound.

(Experiment-2) The cross-linking agent has a half-life
In consideration of e), a dialkyl peroxide was used, and 2,5-dimethyl-2,5-di (t-t) at 1.7 hours / 145 ° C. was used.
(Butylperoxy) hexyne-3 was chosen.

100 parts by weight of crushed pet flakes dehumidified to 100 ppm Perhexin 25B 0.005 parts by weight PN280 5 parts by weight LIQUEMAL SL-800 1.5 parts by weight TP-123 5.0 parts by weight Here, Perhexin 25B: Nippon Oil & Fat Crosslinking agent PN280: High viscosity polyester plasticizer manufactured by Asahi Denka LIQUEMAL SL-800: Ester type lubricant manufactured by Riken Vitamin, stearyl stearate TP-123: Fibrous calcium carbonate manufactured by Okutama Industry This compound is widely used as an extruder. Using a twin-screw extruder (30 mm x 2 screws, L / D = 30), the extrusion conditions were as follows:
Cylinder and die temperature 260 ° C, sizing die temperature 120 ° C, rotation speed 20rpm, die diameter 76mm,
Extrusion was performed using a pipe with an inner diameter of 66 mm.

According to the results of the extrusion test, the variation in the extrusion amount was extremely large, surging frequently occurred, the fluctuation of the resin pressure at the die was not stable, and the pipe strength was 1.0 N / mm ² , like glass. The pipe had poor appearance and large variation in strength, and no effect of the crosslinking reaction was observed. Therefore, it was judged that it was not practical.

In the present invention, a composition containing a carbodiimide compound as a chain extender is used as a raw material. The description and experimental examples of the chain extender carbodiimide compound will be described in detail below. The carbodiimide compound has the following general formula

[0036]

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Wherein R is a hydrocarbon group and n is 1 to 10
0, preferably 1 to 30) and is a chain extender that reacts with high yield to the -COOH group and -OH group at the terminal of the pet resin molecule.

The reaction between the pet resin and the carbodiimide compound is represented by the following formula.

[0039]

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Since the C atom at the center of the structure of the carbodiimide compound is bonded to two N atoms having high electronegativity, the C atom becomes strongly electrophilic, and as shown in the above formula, an -OH group, Reacts readily with -COOH groups.

In this reaction, the carbodiimide compound acts as a chain extender on the pet resin molecule, increases the intrinsic viscosity IV value of the pet resin, and increases the melt viscosity to improve moldability such as extrusion. it can.

A molded product obtained by extruding the chain extension reaction product of the carbodiimide compound has an amorphous structure, and exhibits plastic flow behavior due to increased entanglement of molecules. Also, I
An increase in the V value has led to an improvement in the mechanical strength of the molded article.

The carbodiimide compounds include aliphatic and aromatic monocarbodiimides. Specific examples of preferred carbodiimide compounds include dicyclohexylcarbodiimide, diphenylcarbodiimide, diβnaphthylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, and di-tert-butylisopropylcarbodiimide. The carbodiimide compound is used in an amount of 0.001 to 10 parts by weight based on 100 parts by weight of the entire pet resin.

(Experiment-3) Thickening Effect of Melt Viscosity by Addition of Carbodiimide Compound To clarify the thickening effect of melt viscosity by addition of carbodiimide compound, each formulation shown in the following Table 3 was prepared and measured. went.

[0045]

[Table 3]

In the tables, the amounts are shown in parts by weight. The crushed bottle flakes are flakes having a water content of 100 ppm or less. PA500: Mitsubishi Rayon, homopet resin, IV value 0.76, dehumidified to a water content of 100 ppm or less. Stabacol I: carbodiimide compound manufactured by Bayer. SL800: RIKEN vitamin ester lubricant, stearyl stearate.

The melt viscosity measuring device used for the measurement of the melt viscosity was a Monsanto Processing Meter, with a capillary DD = 0.76 mm, LD = 30.00 mm, a preheating time of 5 minutes, a temperature of a piston 205 ° C., and a barrel 265. ℃,
Extrusion mouth 25 ° C. The extrusion time in each zone was (1) 25 minutes and 40 seconds for the zone, (2) 6 minutes and 35 seconds for the zone, (3) 2 minutes and 31 seconds for the zone, and (4) 71 seconds for the zone. The measurement results of the melt viscosity are as shown in Table 4. Crushed flakes 1
The sample containing only 00 parts by weight was not shown in this table because the molten ribbon was very fine in zones 1 to 4 but could not be measured due to the large swing of the ribbon size due to surging.

[0048]

[Table 4]

The following considerations were obtained from the results of the above viscosity measurement. (1) The pet resin melt shows Newtonian flow. (2) The difference in viscosity between Samples 2 and 3 and between Samples 4 and 5 is due to the difference in apparent viscosity due to the lubricant. (3) The chain extension effect of the carbodiimide compound does not increase the resin viscosity in proportion to the amount of the carbodiimide compound added, but it is clear that the carbodiimide compound has a thickening effect.

(Experiment-4) Effect of carbodiimide compound on fluidity The effect of carbodiimide compound on fluidity was measured by the following formulation. The measurement method was based on JIS K7210 (thermoplastic flowability test), using a melt flow indexer as a fluidity measurement device, at a measurement temperature of 270 ° C., a preheating time of 5 minutes, a load of 2.16 kg · f, and a measurement place. Was conducted at Nisshinbo Tokyo Research Center.

The formulations and results are as follows. Mixing Melt flow PA500 100 parts by weight 116 g / 10 min PA500 100 parts by weight + HMV10B 1 part by weight 33 g / 10 minutes PA500 100 parts by weight + HMV10B 2 parts by weight 24 g / 10 minutes Here, PA500 is a homopet resin I manufactured by Mitsubishi Rayon.
With a V value of 0.76, HMV10B is a carbodiimide compound manufactured by Nisshinbo.

Examination of the results clearly shows that the influence of the carbodiimide compound on the fluidity is remarkable.

(Experiment-5) Influence of carbodiimide compound on strength of molded article An experiment was conducted to clarify the influence of carbodiimide compound on strength of molded article. The following amount of the carbodiimide compound was added to 100 parts by weight of the dried flaked flakes of the recovered PET bottle dehumidified to a water content of 100 ppm or less, and the mixture blended in a closed container was extruded at a cylinder temperature of 265 ° C. using a 40 mm single screw extruder. Molded. JISK6761
(Polyethylene pipe for general use), from the obtained pipe of nominal diameter 65, outer diameter 76mm, inner diameter 66mm
A was cut out.

Formulation number Carbodiimide compound (Nisshinbo HMV10B) 1- (no addition) 2 0.8 parts by weight 3 1.0 parts by weight 4 1.5 parts by weight 5 2.0 parts by weight Tensile testing machine 55
Using a type 44, chuck distance 40mm, test speed 10mm
Per minute, the tensile strength was measured. The results are as follows. Formulation number Tensile strength (N / mm ² ) 1 1.0 2 17.1 3 27.6 4 53.8 5 61.3 As can be seen from the measurement results, the addition of the carbodiimide compound clearly improves the tensile strength of the sample. I do.

(Experiment-6) Behavior of carbodiimide compound on compressive load In order to examine the effect of carbodiimide compound on compressive load, a pet resin, PA500 (IV value 0.76) manufactured by Mitsubishi Rayon Co., Ltd. was vacuum dried to 10 ⁻² TORR. Dehumidified for 3 hours using a CHINO dry mass spectrometer CZA-2000, and confirmed that the water content was 92 ppm, and 100 parts by weight of the carbodiimide compound was not added (formulation 1).
And 1 part by weight of a carbodiimide compound (Nisshinbo HMV10B) (formulation 2).

This compound was charged into a general-purpose twin-screw extruder (30 mm × 2 screws) in an airtight manner, and the temperature was 270 ° C. in a cylinder and a die.
A pipe having a nominal diameter of 65, an outer diameter of 76 mm, and an inner diameter of 66 mm was extruded according to ISK6761 (polyethylene pipe for general use). Cut out sushimen 6A from the obtained pipe,
The pipe was divided into two parts at the center to obtain a sample. A compression test was performed on this sample. The compression test condition is a compression speed of 5 mm
/ Min, compressed to a maximum displacement of 10 mm.

The test results are as follows. Item Formulation 1 Formulation 2 Maximum load (kg · f) 174 191.6 Displacement at break (mm) 7.43 10.00 Young's modulus (kg · f / mm ² ) 70.5 65.0 Break state Break No break From the above results, in the case of Formulation 2 in which the carbodiimide compound was mixed, the value of the maximum stress generated in the material due to the increase in molecular weight and the entanglement of the molecules was smaller than the cohesive force, and the material was ductilely deformed and fractured Was determined not to have occurred.

As described in detail above, according to the mechanism of action of the carbodiimide compound used in the present invention and the experimental data supporting the same, the effect of a chain extender, an increase in IV value, and an increase in melt viscosity of an extruded product The improvement of the mechanical strength of was confirmed.

Although the above description has been made mainly on the case of extrusion molding, the present invention can carry out profile extrusion, sheet extrusion, or injection molding using the raw material composition of the present invention. In addition, a compound for extrusion molding or a compound for injection molding can also be manufactured. In particular, the production of the compound for injection molding will be described.

(Experiment-7) Production of Compound for Injection Molding The compounding of the compound for injection molding requires consideration of the shape L / t of the molded product (L: length of molded product, t: thickness of molded product). In addition, it is necessary to control the fluidity and the drawdown property, and to improve the strength of the molded article is also an essential condition.

In the compounding, a carbodiimide compound is required for increasing the melt viscosity of the pet flakes and improving the mechanical strength, and whisker may be used for reinforcing the mechanical strength and improving the impact resistance. Desirably, in order to improve fluidity, it is desirable to incorporate fibrous calcium carbonate. Further, an ester-type lubricant known to have a suitable lubricating effect as a lubricant for pet resin is added to further improve fluidity. Is preferred. Based on such a concept, the following formulation was prepared as an example.

Mixing Recovered PET bottle crushed flakes (water content of 100 ppm or less) 100 parts by weight Carbodiimide compound (Stavaxol I manufactured by Bayer) 1.2 parts by weight Whisker (Kawatetsu Mining Thaibrex, potassium titanate fiber) 5.0 parts by weight TP123 (Okutama) Industrial, fibrous calcium carbonate) 3.0 parts by weight Riquemar SL800 (manufactured by Riken Vitamin, ester-type lubricant) 1.8 parts by weight
A general-purpose twin-screw extruder manufactured by Nagata Seisakusho Co., Ltd. (screw 30 mm × 2, L / D = 30) was used as an extruder under the conditions of a cylinder temperature of 270 ° C., a die temperature of 260 ° C., and a screw rotation of 20 rpm. Extruded using a honeycomb die.

The ribbon passed through the honeycomb die was immediately cooled in a water tank and then cut into pellets. The resulting pellets were dried in a hot air dryer at 150 ° C. for 2 hours, and then dried for 10 hours.
^-2 Dry with a TORR vacuum dryer for 2 hours.
Stored in layered paper bags. The pellet was formed into a flat plate by a press forming machine at 250 ° C., and the tensile strength was measured.
Good strength was exhibited at 7.5 N / mm ² . Thus, this formulation can be used as an injection molding compound.

[0064]

The present invention will now be described by way of examples, which are not intended to limit the invention. Example 1 A collected PET bottle was washed at 70 ° C. with a shower nozzle of high-pressure hot water of ² kg / cm ² to remove mud, dust, etc., and then a water-injection type pulverizer of VMNT-50 type manufactured by Orient Co., Ltd. While crushing with a (screen 8 mm screen), the flakes were obtained by fir washing. The obtained washed flakes were transported upward while fir-washing on a twin screw conveyor (rotating in different directions) in a rectangular water tank 7 m in length inclined at 25 °.

During this time, mud and dust and the like adhering to the flakes were drained downward, and the crushed flakes of the labels and caps were continuously washed out with a screw conveyor while flowing out from above because of their low specific gravity. The flakes thus washed are dehydrated by 95% with a dehydrator V-400 manufactured by Orient Co., Ltd., and dried with a continuous rotary hot-air dryer (internal temperature: 150 ° C.) for 2 hours to obtain a flake of 10 ^−2. As a result of drying for 3 hours with a vacuum drier having a TORR vacuum degree, the moisture in the flakes was dehumidified to 90 ppm. The flakes dehumidified to 90 ppm were stored in a hopper drier in a nitrogen stream. The mixture was uniformly dispersed in an airtight blender in a nitrogen stream and charged into an extruder.

Formulation-1 Collected PET bottle crushed flakes (moisture 90 ppm) 100 parts by weight Carbodiimide compound (manufactured by Nisshinbo, HMV10B) 1.0 part by weight Riquemar SL800 1.2 parts by weight The obtained composition was used as an extruder. ) Nagata Manufacturing,
Using a general-purpose twin-screw extruder (30 mm x 2 screws, co-rotating, L / D = 30, motor 7.5 kw), the extrusion conditions were cylinder temperature 265 ° C, cylinder head temperature 270 ° C, die temperature 270 ° C, Sizing die temperature (low temperature according to take-off direction) 200 ° C, 180 ° C, 150
At C, the pipe was extruded.

The results of extrusion show that the melt viscosity was increased by the addition of the carbodiimide compound, so that the extrudability was good, the resin pressure at the die portion was stable at 65 kg / cm ² , there was no surging, and the extrusion amount was small. There was no change. The gloss on the inside and outside surfaces of the pipe was good and there was no flow mark.
When a tensile test was performed in accordance with JIS K6761, it was 31.5 N / mm ² , which was far superior to the JIS standard value.

Example 2 Using the dehumidified flakes (moisture 90 ppm) of the collected PET bottle treated in the same manner as in Example 1, the following formulation was prepared.

Formulation-2 Recovered PET bottle crushed flakes (moisture 90 ppm) 100 parts by weight Carbodiimide compound (manufactured by Bayer, Stabacol I) 1.2 parts by weight Riquemar SL800 1.5 parts by weight The extruder and the extrusion conditions were the same as in Example-1. The pipe was extruded in the same manner. The extrusion results were as in Example 1, with good extrusion moldability, constant extrusion rate, no surging, and good and glossy inner and outer surfaces of the pipe. JIS
When a tensile test was performed in accordance with K6761, 32.4 was obtained.
N / mm ² was much better than the JIS standard value.

[0070] Blends of the dehumidification flakes recycled PET bottles were treated in the same manner as in Example -3 Example 1 (water content 90 ppm) and ^{10 -2} TORR 3 hours dehumidified PET resin in a vacuum oven at (moisture 92 ppm) Was used to prepare the following formulation.

Formulation-3 Recycled PET bottle crushed flakes (moisture 90 ppm) 85 parts by weight PET resin PA500 (manufactured by Mitsubishi Rayon, homopet resin, IV value 0.76) 15 parts by weight Carbodiimide compound (Nisshinbo, HMV10B) 0.8 part by weight Part: Riquemar SL800 1.1 parts by weight The obtained composition was used as an extruder and manufactured by Nagata Seisakusho Co., Ltd.
0 mm single screw extruder (L / D = 32, screw pitch: supply part 20D-compression part 2D-dalmage part-measurement part 10
Using D), pipes were extruded at a cylinder temperature of 270 ° C., a die temperature of 265 ° C., a sizing die temperature of 200 ° C., 180 ° C., 150 ° C. (low temperature according to the take-off direction), a screw rotation of 30 rpm. JIS K6
Nominal diameter 75, outer diameter 89mm, inner diameter 78mm according to 761
A die was used.

As a result of the extrusion, the extrudability was good, there was no change in the extrusion amount, there was no surging, and the extrusion amount was constant. When a tensile test was performed in accordance with JIS K6761, it was 30.4 N / mm ² , which was superior to the JIS standard value.

Comparative Example 1 When no carbodiimide compound was used The following formulation was prepared using the dehumidified flakes (moisture 90 ppm) of the collected PET bottle treated in the same manner as in Example 1 without adding the carbodiimide compound.

Formulation-4 Recovered PET bottle crushed flakes (moisture 90 ppm) 100 parts by weight Carbodiimide compound --- 1.2 parts by weight of liquemar SL-800 The extruder and extrusion conditions were the same as those in Example-1 except that a general-purpose twin-screw extruder was used. Used to extrude pipes. As a result of the extrusion, the fluctuation of the extrusion amount was large, and surging occurred frequently. Although there was no flow mark on the pipe, the thickness dimension of the pipe in accordance with JIS K6761 greatly changed, and the pipe strength was 3.8.
N / mm ² was less than the JIS standard value, and the pipe was not practical.

Comparative Example 2 In the case where the flake product contains a large amount of water, the collected PET bottle crushed product was dried with a hot air dryer at 140 ° C. for 2 hours, and used after confirming that the flake flakes had a water content of 1760 ppm. The following formulation was made:

Formulation-5 Collected PET bottle ground flakes (water 1760 ppm) 100 parts by weight Carbodiimide compound (manufactured by Bayer, Stabacol I) 0.4 parts by weight Riquemar SL-800 1.2 parts by weight The extruder is the same as in Example-1. Using a general-purpose twin-screw extruder
Extrusion conditions were the same as in Example 1 to extrude a pipe. The result of extrusion shows that the resin pressure at the die is 15 to 70 kg /
greatly varies cm ^2, and extrusion rate varies according to the pressure fluctuations, surging frequently. The flow marks on the inner and outer surfaces of the pipe were extremely large, and irregularities on the outer surface were also observed, so that there was no practicality. A tensile strength of 3.1N / mm ² JIS K6
761 standard value or less.

This was judged to be because the water in the flakes was rapidly hydrolyzed at a high temperature to lower the molecular weight and lower the melt viscosity. When the water content of the pulverized pet flakes was high, the effect of the carbodiimide compound was diminished, the mechanical strength was not improved, and the appearance of the pipe was poor.

Comparative Example 3 The crushed recovered PET bottle was dried with a hot air drier at 150 ° C. for 4 hours, and after confirming that the moisture content of the dried flakes was 500 ppm, the following formulation was prepared.

Formulation-6 Recycled PET bottle crushed flakes (water content: 500 ppm) 85 parts by weight PET resin PA500 (manufactured by Mitsubishi Rayon, homopet resin, IV value 0.76) 15 parts by weight Carbodiimide compound (manufactured by Bayer, Stabacol) 0.2 parts by weight Part: Riquemar SL800 1.2 parts by weight A pipe was extruded by using an extruder and a 50 mm single screw extruder under the same extrusion conditions as in Example-3. As a result of the extrusion, the fluctuation of the extrusion amount was large, and surging occurred frequently. The resin pressure at the die portion fluctuated greatly from 12 to 80 kg / cm ² .
There is a flow mark on the outer surface of the pipe, the appearance is poor,
There was no practicality. Tensile strength is 3.2 N / mm ² and J
It was below the standard value of IS K6761.

Claims (1)

[Claims] 1. A recovered PET bottle is washed with a high-pressure hot water on the outer surface of the bottle, crushed and washed with a water-injection type crusher to form flakes, and foreign substances adhered to the flakes while being washed in water with a twin screw conveyor. Is separated by specific gravity, and further dehumidified to 100 ppm or less of moisture with hot air and a vacuum drier to produce a dry flake, and 100 to 60 parts by weight of the PET bottle flake and 100 ppm or less of moisture with an intrinsic viscosity IV value of 1.0 or less. PET bottle flakes alone or in a mixture with 0 to 40 parts by weight of the obtained polyethylene terephthalate resin, and carbodiimide compound 0.001
A method for producing a molded product having improved mechanical strength of flakes and pet resin by directly molding a compound obtained by mixing 10 to 10 parts by weight of the composition in an airtight manner.