JPH08188455A - Reutilization of waste thermoplastic resin as resource - Google Patents

Abstract

PURPOSE: To obtain a product excellent in mechanical characteristics and reutilize a waste thermoplastic resin as a resource by adding cement and a hydrophilic substance to the waste thermoplastic resin to which soil is attached, and heating, kneading and forming the mixture and hydrating and curing the formed product. CONSTITUTION: One hundred pts.wt. of a waste thermoplastic resin to which soil is attached, 50-700 pts.wt. of cement and 0.1-20 pts.wt. of a hydrophilic substance are charged into a mixer and heated to a melting point or above of the waste thermoplastic resin and kneaded and formed, or the waste thermoplastic resin and the hydrophilic substance are heated and mixed, and then, the mixture may be kneaded and formed with cement. The resultant formed product is immersed into water or subjected to high temperature and high pressure curing, etc., by post hydration method to promote hydration curing of cement, or the mixture is kneaded with a cement setting controller and water and hydration to promote the curing of cement by a preceding hydration method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for recycling a waste thermoplastic resin such as vinyl chloride resin to which soil is adhered, which is used particularly for vinyl houses, pipes, electric wire coatings and the like.

[0002]

BACKGROUND OF THE INVENTION Waste thermoplastic resins such as vinyl chloride resin, polyester resin, polystyrene resin, polypropylene resin, etc., which are used in agricultural vinyl houses, pipes, electric wire coatings, etc. and have soil attached, or food containers, etc. The waste thermoplastic resins such as vinyl chloride resin, polyester resin, polystyrene resin, polypropylene resin, etc., which are used as packaging materials, etc., have not been established as effective recycling measures at present. Most of the disposal is landfill. And only a part is recycled for boundary piles, coagulation, drainage panels, etc. This is because when the thermoplastic resin is subjected to the second and subsequent heat cycles, the moldability and physical properties deteriorate, and the recovered waste thermoplastic resin contains various types of resins. Therefore, the characteristics of the obtained product were not good.

[0003]

DISCLOSURE OF THE INVENTION Therefore, effective utilization of these waste thermoplastic resins has been demanded. In particular, the amount of thermoplastic resin used for agricultural greenhouses, etc. is enormous, and soil is attached to it, and it is wet with water. Was required to establish a different method.

While earnestly advancing the study for effectively utilizing the waste thermoplastic resin as described above, it was found that the soil and water adhering to the cement would not be a problem if used in combination with cement. However, it was found that simply kneading with cement was not enough, and as a result of further research, it was found that a hydrophilic substance should be added to the waste thermoplastic resin to impart hydrophilicity. Due to this, the waste thermoplastic resin and cement are uniformly dispersed, and the hydrated and hardened thermoplastic resin cement compact has a small linear expansion coefficient, high softening temperature, and excellent flame retardance. Was played. Moreover, the moldability was good.

The present invention has been achieved based on such knowledge, and an object thereof is to provide an effective method for recycling waste thermoplastic resin. The object of the present invention is to heat a mixture containing a waste thermoplastic resin with soil attached, cement, and a hydrophilic substance to a temperature equal to or higher than the melting point of the waste thermoplastic resin, kneading, molding, and then hydration curing. It is achieved by a method for recycling a waste thermoplastic resin, which is characterized in that

In particular, waste thermoplastic resin with soil attached,
Cement, and a hydrophilic substance is charged into a mixer, heated to a temperature above the melting point of the waste thermoplastic resin, kneaded, molded, and then hydrated by a method for recycling waste thermoplastic resin, characterized by To be achieved. Alternatively, the waste thermoplastic resin to which the soil adheres and the hydrophilic substance are put into the mixer,
After heating and kneading the waste thermoplastic resin and the hydrophilic substance in advance, the cement is put into a mixer, and after kneading and molding,
This is achieved by a method for recycling waste thermoplastic resin, which is characterized by hydration curing.

Further, a mixture containing soil-attached waste thermoplastic resin, cement, hydrophilic substance, cement setting regulator, and water is heated to a temperature above the melting point of the waste thermoplastic resin,
This is achieved by a method for recycling waste thermoplastic resin, which is characterized by kneading, molding and hydration curing. Hereinafter, the present invention will be described in detail.

In the method for recycling the waste thermoplastic resin of the present invention, it depends on the type of the recovered waste thermoplastic resin, the mixing amount of foreign matters such as soil (mud and sand), the water content of water, etc. It is roughly classified into a method by post-hydration that accelerates hydration and hardening of cement by immersing a molded body that is heated and melted in water, and waste thermoplastic resin, cement, hydrophilic when kneading that heats and melts. In addition to the substances, a cement coagulation regulator and water necessary for hydrating the cement (especially water in the form of being held by some substance such as crystal water or gelled water) are added, and kneading / molding Sometimes there is a method by pre-hydration that accelerates hydration and hardening of cement.

The post-hydration method is to knead and mold cement and a hydrophilic substance into waste thermoplastic resin, and in the case of waste thermoplastic resin that is not wet with water or when reprocessing a molded product. Is suitable. When kneading waste thermoplastic resin, cement and hydrophilic substances, it can be heated above the melting point of waste thermoplastic resin,
Any type of mixer may be used as long as each material can be uniformly kneaded, but a Banbury mixer, a kneader, an extruder, or the like is generally used.

The shape of the waste thermoplastic resin charged into the mixer may be a relatively large size as long as it is a sheet shape, but in the case of a plate-shaped product, it is preferable to crush it into chips of 5 mm or less. . Note that, in any case, it is preferable that the shape is chip-like. When the waste thermoplastic resin and the hydrophilic substance are easily compatibilized, the materials may be added to the mixer at the same time and heated and kneaded, but it is difficult to make them compatible. In this case, it is preferable that the waste thermoplastic resin and the hydrophilic substance are charged in advance, heated and melted to be compatibilized, and then cement is added and kneaded.

In the case of post-hydration, that is, the ratio of the waste thermoplastic resin to which the soil adheres, the cement and the hydrophilic substance is 50 to 700 of the cement with respect to 100 parts by weight of the waste thermoplastic resin. It is preferable that the weight ratio (desirably 50 to 600 parts by weight) and the hydrophilic substance be 0.1 to 20 parts by weight (desirably 1 to 15 parts by weight). In addition to these, it is also possible to add a plasticizer, a stabilizer and the like.

The kneaded waste thermoplastic resin cement is molded by an appropriate method such as injection molding, extrusion molding, roll molding, injection molding or press molding depending on the shape of the product to be molded and the size of the members. It This molded waste thermoplastic resin cement body has excellent properties that cannot be obtained from conventional waste thermoplastic resin recycled products by accelerating the hydration hardening of the cement by immersion in water or curing at high temperature and high pressure. Will be things.

The rate of hydration hardening varies depending on the thickness of the molded product, the amount of hydrophilic substance, the amount of cement added, etc., but the faster the member is and the more hydrophilic substance and cement are, the faster. Tends to become. The pre-hydration method uses waste thermoplastic resin to retain cement, hydrophilic substances, cement setting regulators, and water necessary for hydration of cement (especially water such as crystal water or gel water). It is also applicable to any state such as waste thermoplastic resin wet with water or waste thermoplastic resin not wet with water.

The kneading of each material such as waste thermoplastic resin and cement can be carried out by any mixer as long as it can be heated above the melting point of the waste thermoplastic resin and can knead each material uniformly.
In general, steam is ejected during heating and kneading, and a pressure kneader is used because it is necessary to suppress it. As for the shape of the waste thermoplastic resin in the case of pre-hydration, it is desirable to crush it into fine particles (chips) as much as possible because the molding of the thermoplastic resin cement to be heated and kneaded is limited in time. .

Melting and kneading of the material is carried out in a short time after the waste thermoplastic resin and the cement are compatibilized by the hydrophilic substance and the cement coagulation regulator, the crystalline substance or gel holding water is added, and the mixture is molded. Since it is necessary to complete the hydration hardening of the cement, it is easy to supply the water necessary for the hydration hardening of the cement from the inside during melting and kneading. It is important to stir and add to the mixer. Even if all the materials are not stirred in advance, it is important to stir the cement, the cement setting regulator, the crystalline substance retaining water and the gel.

In the case of pre-hydration, that is, the ratio of the waste thermoplastic resin, the cement, the hydrophilic substance, the cement setting regulator and the water is 50 to 50 parts by weight of the cement with respect to 100 parts by weight of the waste thermoplastic resin. 800 parts by weight (preferably 50 to
600 parts by weight), 0.1 to 20 parts by weight of hydrophilic substance (preferably 1 to 15 parts by weight), and 0.1 to 10 parts by weight (preferably 0) of cement setting regulator to 100 parts by weight of cement. 0.5 to 8 parts by weight) and 10 to 35 parts by weight of water (desirably 10 to 20 parts by weight). In addition to these, it is also possible to add a plasticizer, a stabilizer and the like.

In the molding method by prehydration, since the temperature during heating and kneading is 100 ° C. or higher, it does not become water vapor and does not spout water during kneading, and it becomes vapor from the thermoplastic resin cement body to be kneaded. It is important to efficiently hydrate and harden the cement without delaying it, and to delay the rapid hydration and hardening of the cement so that it has a certain molding time.

For this purpose, a pressure kneader of 8 kgf / cm ² or more is used in order to suppress the ejection of steam at the time of kneading, or the water content is held in a crystalline substance or a gel substance. It is preferable to prevent rapid water loss and to effectively use a cement setting retarder as a cement setting regulator. The waste thermoplastic resin can be used for various uses (products). Further, as the thermoplastic resin, vinyl chloride resin, polyethylene, polystyrene, polypropylene, ethylene vinyl acetate,
Examples thereof include acrylonitrile-butadiene-styrene copolymer, vinylidene chloride, nylon, polyethylene terephthalate, polycarbonate, polymethylmethacrylate, polyacrylate and the like. Further, a mixture of two or more kinds of these resins may be used.

Examples of the cement include ordinary Portland cement, early-strength Portland cement, white cement, moderate heat cement, ultra-rapid hardening cement, blast furnace cement, fly ash cement, alumina cement and the like.
Of course, hydraulic cements other than these can be used as long as they are hydraulic cements. A hydrophilic substance is a substance that imparts hydrophilicity by being compatibilized with a waste thermoplastic resin, and can be dispersed or dissolved in the waste thermoplastic resin by a polymer alloy to harden the hydraulic cement. Imparts sex. Examples of such a substance include olefin oxides such as polyethylene oxide and polypropylene oxide, simple substances such as PVA, polyethylene glycol, and polyhydric alcohols such as polypropylene glycol, and mixtures of two or more thereof, or copolymers or derivatives thereof, such as polyurethane. Nonionic surfactants containing prepolymers or surfactants, polyoxyethylene alkyl ethers of polyoxyethylene alkyl ethers and polyhydric alcohols which are raw materials thereof, polyhydric alcohols, polyethylene glycol fatty acid esters, esters of polyhydric alcohols Are exemplified.

Examples of the cement setting regulator include sodium citrate, sodium heptonate, sodium tartrate, ketones such as acetylacetone and acetoacetic acid, and Rochelle salt. Examples of the water of crystallization that retains water in the form of water of crystallization include, for example, Etrin Guide 3CaO · Al ₂ O ₃ · 3.
2H ₂ O, an alumina cement that indirectly produces this
Gypsum mixture, 12CaO / 7Al ₂ O ₃ gypsum mixture,
Examples thereof include aluminum hydroxide or aluminum hydroxide gel, silica gel, bentonite, zeolite, magnesium sulfate hydrate, calcium chloride hydrate, magnesium chloride hydrate.

Examples of gel-like water substances that retain water in a gel form include starch-acrylonitrile graft polymer, starch-acrylic acid graft polymer, starch-styrene sulfonic acid graft polymer, starch-vinyl sulfonic acid graft polymer. Examples include polymers, other starch derivatives, cellulose-styrene sulfonic acid graft polymers, hiruaronic acid, agarose, chitosan, collagen, gelatin, starch, casein, and methyl cellulose. Further, synthetic polymer-based PVA cross-linked polymer, PVA elastomer, acrylic acid cross-linked polymer, acrylic ester-vinyl acetate copolymer partial hydrolyzate, polyacrylonitrile polymer partial hydrolyzate, hydroxy ether methacrylate polymer. Also included are isobutylene maleic anhydride copolymer salts, polypropylene glycol-diacrylate copolymers, polyeletinimine copolymers, and the like.

The thermoplastic resin cement molded product obtained by pre-hydration has excellent properties which cannot be obtained by a conventional recycled product of waste thermoplastic resin. That is, when a large amount of cement is mixed, it becomes flame retardant, the linear expansion coefficient is reduced, the thermal softening point is improved, and the weather resistance is improved. The molded product (thermoplastic resin cement molded product) obtained by the method for recycling waste thermoplastic resin of the present invention has a very wide range of uses, and is a wall material such as an outer wall panel, an inner wall panel, a painted wall base panel, and a partition panel. , Floor panels, floor tiles, floor materials such as OA floors, sewer pipes, cable troughs, manholes, electric buildings, pipe materials such as U-shaped grooves, discarded formwork, formwork, spacers,
Concrete products such as mockers, road materials, sound absorbing boards,
It is used for various products such as sound insulation boards and blocks.

[0023]

【Example】

[Example 1] Table-1 Actual-1 Actual-2 Actual-3 Ratio-1 Ratio-2 Waste thermoplastic resin (parts by weight) 100 100 100 100 100 100 Cement (parts by weight) 200 300 400 200 200 300 Hydrophilic substance ( Parts by weight) 3 3 3 0 0 * Waste thermoplastic resin; vinyl chloride resin (crushed into chips) that is used in agricultural vinyl houses and has about 10 wt% soil (mud) adhered * Cement; Chichibu Onodasha Normal Portland Cement * Hydrophilic substance; Polyethylene oxide manufactured by Meisei Chemical Co., Ltd. After kneading the compounding materials in Table 1 above with a Banbury mixer heated to 160 ° C for 6 minutes, roll rolling to obtain a thickness of 5
It was formed in a plate shape of mm. The molded plate-shaped body was immersed in water and the physical properties were measured after 7 days, and the results are shown in Table 2.

Table-2 Actual-1 Actual-2 Actual-3 Ratio-1 Ratio-2 Kneading / Moldability Good Good Good Somewhat Poor Linear Expansion Coefficient (/ ° C) 5 × 10 ⁻⁵ 3 × 10 ⁻⁵ 2 × 10 ^-5 6 × 10 ^-5 5 × 10 ^-5 Softening temperature (° C.) 95 101 116 116 92 93 According to this, even if a large amount of cement is added in the present invention to which a hydrophilic substance is added, It can be seen that the kneading / moldability is good, the linear expansion coefficient is small, and the softening temperature is high.

Example 2 Table-3 Real-4 Real-5 Ratio-3 Ratio-3 Ratio-4 Waste thermoplastic resin (parts by weight) 100 100 100 100 Cement (parts by weight) 300 300 300 300 300 Hydrophilic substance (parts by weight) ) 4400 * Waste thermoplastic resin; vinyl chloride resin + about 15 wt% soil (mud) + ABS resin (1: 1) (crushed into chips) * Cement; ordinary white Portland semé manufactured by Chichibu Onoda Co., Ltd. * Hydrophilic substance; polyethylene glycol The waste thermoplastic resin and the hydrophilic substance in the compounding materials in Table 3 above are put into a kneader heated to 150 ° C and kneaded for 5 minutes, then cement is added and kneaded for 4 minutes. After doing
Immediately, it was put into an extruder to obtain a columnar molded body. The molded plate-shaped body was immersed in water and the physical properties were measured after 7 days, and the results are shown in Table 4.

[0026] Table -4 real -4 actual -5 ratio -3 ratio -4 kneading and moldability good good bad bad tensile strength ^{(kgf / cm 2) 234 197} 188 159 According to this was added a hydrophilic substance It can be seen that the product of the present invention has good kneading / moldability and also excellent mechanical strength.

[Example 3] Table-5 Actual-6 Actual-7 Ratio-5 Waste thermoplastic resin (parts by weight) 100 100 100 Cement (parts by weight) 500 500 500 Hydrophilic substance (parts by weight) 6 6 0 Condensation Retarder (part by weight) 12 12 0 Water (part by weight) 100 100 100 Crystal water substance (part by weight) 0 10 10 * Waste thermoplastic resin: polypropylene, 5 wt% water content, 8 wt% soil (mud) adhered (Crushed into chips) * Cement; Ordinary Portland cement manufactured by Chichibu Onoda Co. * Hydrophilic substance; PEO (molecular weight 20000) reacted with TDI to block 3% of NCO residue with MEK oxime * Set retarder; Sodium heptonate * Water of crystallization; Magnesium sulphate Cement, hydrophilic substance in the compounding materials in Table 5 above,
A setting retarder and a water of crystallization substance are added to water, stirred, and allowed to stand for 30 minutes. This mixture and the waste thermoplastic resin are put into a high-pressure press kneader (the pressure of the press lid is 10 kgf / cm ² ) and 180
Knead for 8 minutes at ℃. The kneaded material was press-molded by applying a pressure of 100 kgf / cm ² , to obtain a columnar molded body. The physical properties of this molded product were measured, and the results are shown in Table-6.

Table-6 Actual-6 Actual-7 Ratio-5 Kneading / Moldability Good Good Poor Tensile Strength (kgf / cm ² ) 311 330-Softening Temperature (° C) 165 172-According to the hydrophilic substance It can be seen that, in the present invention to which the cement setting regulator is added, the kneading / molding property is good and the mechanical strength is also excellent. In particular, in the case of using the water of crystallization, not only water-7, but also water of crystallization-7, the results are even better than those of water-6.

Example 4 Table-7 Actual-8 Actual-9 Actual-10 Ratio-6 Waste thermoplastic resin (part by weight) 100 100 100 100 100 Cement (part by weight) 300 300 300 300 300 Hydrophilic substance (part by weight) ) 4 4 4 0 Set retarder (parts by weight) 10 10 10 0 Water (parts by weight) 45 45 45 45 45 Gel water substance (parts by weight) 0 2 4 0 * Waste thermoplastic resin; polyethylene terephthalate containing some polyethylene , 20wt% soil (mud) adhered (crushed into chips) * Cement; ordinary Portland cement and alumina cement (2: 1) * hydrophilic substance; polyethylene oxide * set retarder; sodium citrate * gel water substance; Water-absorbent resin Waste thermoplastic resin, cement, hydrophilic substance, set retarder, and gel water substance in the compounding materials of Table 7 above are mixed and mixed. Add to water and stir. This mixture is put into a pressure kneader (the pressure of the pressure lid is 8 kgf / cm ² ) and kneaded at 250 ° C. for 6 minutes. This kneaded product was injection-molded to obtain a columnar molded body. The physical properties of this molded product were measured, and the results are shown in the table.
8 shows.

Table-8 Actual-8 Actual-9 Actual-10 Ratio-6 Mixing / moldability Good Good Good Poor Tensile strength (kgf / cm ² ) 356 375 392 − Coefficient of linear expansion (/ ° C) 3 × 10 ^{− 5} 3 × 10 ⁻⁵ 3 × 10 ⁻⁵ − Softening temperature (° C.) 145 145 148 − According to this, a mixture without addition of a hydrophilic substance, a cement setting regulator and gel water has a fluidity at the time of kneading. However, in the case of the present invention, good kneading and moldability were obtained, and in the case of Examples 9 and 10 in which gel water was also added, more excellent results were exhibited. You can see that

[0031]

[Effect] According to the present invention, the waste thermoplastic resin is effectively recycled, and the obtained product has excellent mechanical properties.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B29B 17/00 ZAB 9350-4F C04B 28/02 ZAB // (C04B 28/02 18:20 24: 32) Z B29K 101: 12 105: 26 C04B 103: 40 ZAB 111: 20 ZAB (71) Applicant 000223414 Tsutsunaka Plastic Industry Co., Ltd. 3-5-11 Doshomachi, Chuo-ku, Osaka-shi, Osaka (71) Applicant 000010065 Fukubi Chemical Industry Co., Ltd. 33-33, Sanhachisha-cho, Fukui City, Fukui Prefecture (71) Applicant 000201582 Maezawa Chemical Co., Ltd. 3-2-9, Kyobashi, Chuo-ku, Tokyo (71) Applicant 000005913 Mitsui & Co., Ltd. 1-2-1, Otemachi, Chiyoda-ku, Tokyo (72) Inventor Yosaburo Osawa 391-12 Hizuka, Kumagaya City, Saitama Prefecture

Claims (7)

[Claims] 1. A method of heating a mixture containing waste thermoplastic resin, cement, and a hydrophilic substance, to which soil is adhered, to a temperature equal to or higher than the melting point of the waste thermoplastic resin, kneading, molding, and then hydration curing. And a method for recycling waste thermoplastic resin. 2. The waste thermoplastic resin to which soil is adhered, cement, and a hydrophilic substance are put into a mixer and heated to a temperature equal to or higher than the melting point of the waste thermoplastic resin, and kneading and molding are performed. The method for recycling the waste thermoplastic resin according to claim 1. 3. A waste thermoplastic resin to which soil is adhered and a hydrophilic substance are charged into a mixer, the waste thermoplastic resin and the hydrophilic substance are heated and kneaded in advance, and then the cement is added to the mixer. The method for recycling a waste thermoplastic resin according to claim 1, which comprises charging, kneading and molding. 4. The ratio of the waste thermoplastic resin to which soil adheres, the cement and the hydrophilic substance is the waste thermoplastic resin 10
Cement of 50 to 700 parts by weight and hydrophilic substance of 0.1 to 20 parts by weight relative to 0 parts by weight of the waste thermoplastic resin according to any one of claims 1 to 3. Resource recycling method. 5. A mixture containing waste thermoplastic resin to which soil is adhered, cement, a hydrophilic substance, a cement coagulation modifier, and water is heated to a temperature equal to or higher than the melting point of the waste thermoplastic resin, kneading, molding, A method for recycling a waste thermoplastic resin, which comprises hydration curing. 6. The ratio of waste thermoplastic resin to which soil is adhered, cement, hydrophilic substance, cement setting regulator and water is 50 to 800 parts by weight of cement with respect to 100 parts by weight of the waste thermoplastic resin. Parts, the hydrophilic substance is 0.1 to 20 parts by weight, the cement setting regulator is 0.1 to 10 parts by weight, and the water is 10 to 35 parts by weight with respect to 100 parts by weight of the cement. The method for recycling the waste thermoplastic resin according to claim 5. 7. The method for recycling the waste thermoplastic resin according to claim 5 or 6, wherein the water includes water retained in the form of water of crystallization or gel water.