JP2002302595A - Black pet sheet made of recycled product as main raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet having excellent thermoformability in a recycled polyethylene terephthalate(PET) sheet having improved weather resistance by adding a carbon black powder. SOLUTION: This black recycled PET sheet is characterized by compounding carbon black in an amount of 0.1-5 pts.wt. based on 100 pts.wt. of a recycled PET and a copolymer PET in an amount of >=20 pts.wt. based on 100 pts.wt. of the recycled PET in the recycled resin consisting essentially of the PET.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to discarded PET.
The present invention relates to a black PET sheet obtained by collecting and reusing a recycling resin from a bottle, having good weather resistance and good thermoformability. More specifically, the present invention relates to a recycled PET sheet which is black and suitable as a cooling tower filler formed by thermoforming.

[0002]

2. Description of the Related Art At present, PET resins are widely used as molding materials for containers, packaging films, miscellaneous goods, electronic parts, etc. due to their excellent moldability, appearance, heat resistance, transparency and low cost. Used in various fields. In particular, the production volume of stretch-blow molded PET bottles for beverages and seasonings is increasing year by year. Along with this, the amount of used, unused and discarded PET bottles is also increasing, which has become a social problem.

[0003] Some of the used PET bottles that are no longer needed are recovered and recycled into polyester fibers and the like, but new applications and new molding methods that form a large market have not been implemented.

[0004] On the other hand, the weather resistance of PET resin is not sufficient, and problems such as coloration and reduction in strength are caused by light deterioration and hydrolysis. Therefore, in the case of a product used outdoors, it is difficult to use PET alone, and in many cases, a weather-resistant compound is applied. One example is the addition of organic and inorganic UV absorbers and carbon black.

[0005] The PET of the compound having improved weather resistance is used.
Thermoforming of the sheet is usually performed, but at that time, in a sheet colored with black by adding carbon black powder, carbon particles become a nucleating agent, and the crystallization speed of the PET resin is increased. Crystallization proceeds considerably before reaching the molding temperature. As a result, there is a problem that the stretching stress becomes extremely high, the shaping becomes insufficient, and only a sheet having extremely poor moldability can be obtained.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a recycled PET sheet having improved weatherability by adding carbon black powder and having excellent thermoformability.

[0007]

The present invention relates to a black PE to which carbon black having a high crystallization rate is added.
A method for improving the thermoformability of a T sheet has been found. The gist of the method is that carbon black is contained in a recycled resin containing polyethylene terephthalate (PET) as a main component and 0.1% based on 100 parts by weight of the recycled PET. 1 to 5
The black recycled PET sheet or the copolymerized PET is characterized in that 20 parts by weight or more of the copolymerized PET is blended with respect to 100 parts by weight of the recycled PET.
2. A copolymerized PET in which ethylene glycol is replaced with cyclohexanedimethanol by 30 mol% or more.
The reclaimed black PET sheet or the reclaimed resin mainly composed of polyethylene phthalate is discarded PET
2. A recycled PET sheet according to claim 1, which is a bottle, or a recycled PET containing recycled carbon black in polyethylene terephthalate (PET) as a main component.
0.1 to 5 parts by weight per 0 parts by weight of PET and 30 parts of ethylene glycol in cyclohexanedimethanol.
Mol% or more of the copolymerized PET is replaced with recycled PET100
A cooling tower filler obtained by thermoforming a black reclaimed PET sheet, characterized in that 20 parts by weight or more are blended with respect to parts by weight.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. As the recycled PET resin used in the present invention, flakes obtained by collecting waste PET bottles from the market, sorting, washing, and pulverizing them are preferable because those having a certain quality can be obtained most stably. The size of the pulverized material is not particularly limited as long as it can be supplied to a molding machine.
However, if the size is too large, a bridge is formed in the hopper or a biting failure occurs in the screw feeder groove. Therefore, the size is preferably 0.5 to 8 mm. Also PET
A resin obtained by remelting and kneading flakes to form pellets may be used.

The carbon black used in the present invention is:
Powdered and granular carbon, channel black, furnace black, acetylene black, thermal black,
Lamp black or the like is used. Preferably, furnace black, acetylene black, or the like is used. For example, Vulcan XC72 manufactured by CABOT of the United States, Asahi HS-500 manufactured by Asahi Carbon Co., Ltd., Ketchin Black EC manufactured by Akzo of the Netherlands, and SEA manufactured by Tokai Carbon Co., Ltd.
ST-116 and the like can be used.

The carbon black powder is made of recycled PET10
0.1 to 5 parts by weight is added to 0 parts by weight. If the amount of carbon black is less than 0.1 part by weight, the amount of transmitted ultraviolet light increases, and the weather resistance becomes poor. On the other hand, if the addition amount of carbon black is more than 5 parts by weight, carbon black becomes a nucleating agent and tends to crystallize, so that the moldability deteriorates.

The copolymerized PET used in the present invention includes terephthalic acid, ethylene glycol and other copolymerized components,
That is, it is a copolymerized polyethylene terephthalate derived from another dicarboxylic acid and / or diol, and crystallization is suppressed by the action of these copolymerized components, and thermoforming is facilitated. Specific examples of the other copolymer components constituting the copolymerized polyethylene terephthalate include aromatic dicarboxylic acids such as isophthalic acid and 2,6-naphthalenedicarboxylic acid, diethylene glycol, neopentyl glycol, and cyclohexane dimethanol. Diols can be mentioned as representative examples. Of these, isophthalic acid and cyclohexane dimethanol are particularly preferred, and cyclohexane dimethanol is particularly preferred.

[0012] As such a copolymerization component, ethylene glycol of PET is added to cyclohexanedimethanol.
Those substituted with 0 mol% or more are preferable because they are easily available. When the amount of the copolymer component is very small, the presence of the amorphous portion is reduced, and the temperature-rising crystallization temperature is lowered.

The addition ratio of the copolymerized PET is desirably 20 to 40 parts by weight, and when it is less than 20 parts by weight, the effect of suppressing the crystallinity of the sheet is small, and the crystallization proceeds during preheating in thermoforming to deteriorate the formability. . If the amount is more than 40 parts by weight, there is no problem in moldability, but the amount of PET bottle flakes, which is the original purpose, is undesirably reduced.

This copolymerized PET may be an unused resin, but can be manufactured at lower cost by using trimming scraps, offcuts and scraps of a sheet whose raw material composition is known. This recycled PET is formed into a sheet by various single-screw or twin-screw extruders.

As the thermoforming method of the black PET sheet of the present invention, the sheet can be produced by the equipment and method generally used for producing a thermoplastic resin composition. Preferably, a single-screw and twin-screw extruder is used to knead and extrude the T
A method of forming a sheet from a die or the like is used.

Further, as a method of thermoforming the black PET sheet obtained in the present invention, the sheet is heated by a heater for a predetermined time, the mold is pressed against the heated sheet, and the inside of the mold is evacuated and evacuated. Then, the sheet is formed along the inner surface of the mold. A so-called vacuum forming method is used.

[0017]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In addition, the characteristic evaluation in an Example was determined by the following methods. (1) Vacuum Formability A sheet heated to a sheet temperature of 120 ° C. was vacuum formed using a mold having a diameter of 15 mm and a depth of 10 mm, and the fidelity of a corner portion of a molded product was visually evaluated. (2) Weather Resistance A test piece irradiated with ultraviolet rays by a sunshine weather meter for 600 hours was subjected to a tensile test according to JIS-K7113, and evaluated by elongation retention. × with a retention rate of 20% or less,
20 to 50% was rated as △, and 50% or more was rated as ○. (3) Crystallization temperature Temperature rise rate 10 ° C /
The crystallization temperature (Tcc) was determined from 20 ° C. under the conditions of minutes.

Example 1 10 parts by weight of a master batch containing 10% by weight of carbon black was added to 100 parts by weight of PET bottle flakes of West Japan Pet Recycling Co., Ltd.
30 parts by weight of Eastman Chemical Co. Easter PETG copolyester 6763 were blended, and a barrel temperature of 270 ° C., an extrusion rate of 5 kg / Hr, a screw rotation of 60 rpm, a thickness of 0.5 mm, and a Toyo Seiki co-axial twin screw extruder 2D25WS were used. A black recycled PET sheet having a width of 140 mm was formed. Using the sheet, vacuum forming was performed by a vacuum forming machine using a mold having a diameter of 15 mm and a depth of 10 mm.

Example 2 10 parts by weight of a master batch containing 10% by weight of carbon black was added to 100 parts by weight of a PET bottle flake manufactured by West Japan Pet Recycling Co., Ltd.
30 parts by weight of scrap flakes of a PETG sheet for molding were blended to prepare a sheet in the same manner as in Example 1, and then vacuum molded to obtain a molded product.

Example 3 Molding was carried out in the same manner as in Example 1 except that the amount of carbon black added was 0.1 part by weight.

Example 4 The amount of carbon black added was 2
The molding was performed in the same manner as in Example 1 except that the amount was changed to parts by weight.

Example 5 The amount of carbon black added was 5
The molding was performed in the same manner as in Example 1 except that the amount was changed to parts by weight.

Example 6 Molding was performed in the same manner as in Example 1 except that 20 parts by weight of Easter PETG copolyester 6763 was blended.

Example 7 Molding was carried out in the same manner as in Example 1 except that 40 parts by weight of Easter PETG copolyester 6763 was blended.

Comparative Example 1 10 parts by weight of a master batch containing 10% by weight of carbon black was blended with 100 parts by weight of a PET bottle flake manufactured by West Japan Pet Recycle Co., Ltd., and a sheet was prepared in the same manner as in Example 1 and then vacuum formed. And a molded product was obtained.

Comparative Example 2 Eastman Chemical Easter PETG copolyester 67 was added to 100 parts by weight of West Japan Pet Recycle PET bottle flakes.
63 was mixed in 30 parts by weight to form a sheet in the same manner as in Example 1, and then vacuum formed to obtain a molded product.

Comparative Example 3 A sheet was formed in the same manner as in Example 1 by blending 20 parts by weight of a master batch containing 50 parts by weight of carbon black, and then vacuum formed to obtain a formed product.

Comparative Example 4 Molding was performed in the same manner as in Example 1 except that 10 parts by weight of Easter PETG copolyester 6763 was blended.

Table 1 shows the amounts of raw materials and the evaluation results of Examples 1 to 7 and Comparative Examples 1 to 4.

[Table 1]

A brief description of Table 1 is provided below.

For Examples 1, 3 to 7, the recycled PET
0.1-5 parts by weight of carbon black and 100 parts by weight of PETG6 (manufactured by West Japan Pet Recycle Co.)
763 (manufactured by Eastman Chemical Co., Ltd.) was molded and tested at 20 to 40 parts by weight. As a result of the evaluation of the characteristics of the vacuum formability and the weather resistance, it is found that there is no problem. It is found that the temperature rise crystallization temperature is 125 to 128 ° C., which is higher than the thermoforming temperature 120 ° C.

In Example 2, the same property evaluation was conducted by replacing PETG6763 (manufactured by Eastman Chemical Co.) with 30 parts by weight of PETG sheet flakes (crushed PETG sheet, manufactured by the company), that is, replacing the PETG sheet flakes with recycled PETG. It was found that there was no problem in both vacuum formability and weather resistance. Regarding the temperature rise crystallization temperature,
It turns out that there is no problem at 127 ° C.

With respect to Comparative Example 1, the PETG6 of Example 1 was used.
763 (manufactured by Eastman Chemical Company) was set to 0 parts, and the characteristics were similarly evaluated. Since there is no amorphous part, the temperature rise crystallization temperature is as low as 112 ° C., which indicates that the vacuum formability is poor.

For Comparative Example 4, the PETG6 of Example 1 was used.
763 (manufactured by Eastman Chemical Company)
The characteristics were evaluated in the same manner. Although the amorphous portion was increased as compared with Comparative Example 1, and the temperature rise crystallization temperature was slightly increased to 115 ° C., it was not sufficient, and it was found in the evaluation of characteristics that the vacuum formability was poor.

With respect to Comparative Example 2, the same property evaluation was performed with the carbon black of Example 1 set to 0 parts, but it was found that the weather resistance was poor because no carbon black was added.

With respect to Comparative Example 3, the same property evaluation was performed using 10 parts of the carbon black of Example 1, but the carbon black was used as a nucleating agent and crystallization was promoted. You can see that it is.

As described above, according to the present invention, recycled PET to which carbon black has been added, which has been difficult to thermoform, has been used.
The formability of the sheet can be improved. A molded article obtained by thermoforming a PET sheet colored black with carbon black has a large ultraviolet shielding effect and excellent weather resistance, and can be used outdoors for a long time without any problem.

Claims (4)

[Claims] 1. Polyethylene terephthalate (PET)
Of carbon black in recycled resin containing
A black recycled PET sheet comprising 0.1 to 5 parts by weight based on 100 parts by weight of ET and 20 parts by weight or more of copolymerized PET based on 100 parts by weight of recycled PET. 2. The black recycled PET sheet according to claim 1, wherein the copolymerized PET is a copolymerized PET in which ethylene glycol of PET is replaced with cyclohexane dimethanol by 30 mol% or more. 3. The black recycled PET sheet according to claim 1, wherein the recycled resin mainly composed of polyethylene terephthalate is a discarded PET bottle. 4. Polyethylene terephthalate (PET)
Of carbon black in recycled resin containing
0.1 to 5 parts by weight for 100 parts by weight of ET, and P
Recycled copolymerized PET in which ethylene glycol of ET is replaced with cyclohexanedimethanol by 30 mol% or more
20. A cooling tower filler obtained by thermoforming a black recycled PET sheet, wherein 20 parts by weight or more are blended with respect to 100 parts by weight of T.