JP2014133776A - Resin composition for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for injection molding capable of making a black speck inconspicuous and allowing molding of a resin molding product with higher lightness.SOLUTION: At least a white pigment and chromatic dyestuff are added in a recycled resin having foreign substances. The white pigment and chromatic dyestuff are added within a range of at least 1-16 parts by weight in a total amount. Accordingly, even in a case of a resin molding product including a resin composition using the recycled resin mixed with metals, rubbers or heat cured products such as coatings, a black speck can be made inconspicuous and coloration with higher lightness than a conventional one can be achieved.

Description

  The present invention relates to a resin composition for injection molding using a recycled resin.

  In recent years, concern about the environment and resource depletion has increased, and the realization of a recycling society has become an urgent task. Among them, as for resin materials, the use of recycled resin is being promoted.

  There are three types of resin recycling methods: material recycling, chemical recycling, and thermal recycling.

  Material recycling refers to the act of recycling discarded resins as raw materials for recycled resin after processing such as crushing and dissolution.

  Chemical recycling refers to an act of obtaining petroleum raw materials and the like and reusing them as product raw materials by chemically decomposing discarded resins.

  Thermal recycling refers to an act of recycling discarded resins as fuel by processing them.

  Among the above three types of recycling methods, material recycling has attracted attention from the viewpoint of recycling.

As a material recycling method for resin products, the same kind of resin is sorted from the resin parts of the discarded product, and the resin to be recycled is pulverized, melted by heating, and then again granulated. This method is mainly adopted.
The resin sorting method is mainly classified into manual dismantling sorting and automatic sorting.

  Manual dismantling is a method in which humans sort metal and resin parts, etc., according to the type of material from discarded products. Widely used.

  However, at home appliance recycling plants, resin parts that can be manually dismantled are already sorted and collected.To increase the amount of manual dismantling beyond the current level, parts that are difficult to dismantle are targeted, and cost increases are an issue. Become.

  For this reason, an automatic sorting method has attracted attention.

  The automatic sorting method is a method of crushing waste parts that could not be separated by manual dismantling after removing metal and resin parts from the discarded products, and separating and collecting each material from the crushed mixed material. It is.

  Examples of the automatic sorting method include water specific gravity sorting, electrostatic sorting, and near infrared sorting.

  However, the resin materials sorted by any of the above-described automatic sorting methods contain a large amount of metals, rubbers, heat-cured products such as paint, etc. contained in the original product. This foreign matter causes a decrease in physical properties of the molded product of the recycled resin, and there are many foreign matters called black spots on the appearance of the molded product.

  In particular, molded products of recycled resin can be used for parts that are not visible from the outside due to a decrease in designability, but it is difficult to adopt them for external parts or semi-external parts of products. The amount cannot be expanded, making it difficult to expand recycling.

  In order to solve such a problem, a chromatic resin composition in which a white pigment, a black pigment, or a chromatic color pigment is added to waste plastic to make foreign matter invisible has been proposed (for example, Patent Document 1). .

  In Patent Document 1, as a method of reusing a recycled resin containing a thermoplastic resin such as a polypropylene resin as a main component, a white pigment having a concealing property and a desired chromatic pigment are newly blended, so that other than black Or a technique for recoloring other than the color of the recovered resin.

International Publication No. 03/095531

  However, although the method described in the above-mentioned patent document can make the black spots inconspicuous, there is a problem that the brightness of the molded body is lowered.

  The present invention solves the above-mentioned conventional problems, and provides a resin composition for injection molding capable of molding a resin molded product having higher brightness while making black spots inconspicuous.

  In order to solve the above-mentioned conventional problems, the resin composition of the present invention comprises at least 1.0 part by weight and a total of 16.0 parts by weight of a total amount of a white pigment and a chromatic dye having a concealing property in a recycled thermoplastic resin containing foreign substances. Add in the range of parts by weight or less.

  Even if the resin molded product is molded from a resin composition using a recycled resin mixed with a large amount of thermosetting materials such as metals, rubbers, paints, etc., the appearance quality does not deteriorate due to black spots. It can be used as an external part.

Cross section of injection molded product Process drawing for obtaining the injection-molded article in Embodiment 1 of the present invention

  In the resin composition of the first invention, a white pigment having a concealing property and a chromatic dye are added to a recycled thermoplastic resin containing foreign substances in a total amount of 1.0 to 16.0 parts by weight. ing.

  As a result, even with a resin molded product manufactured using a resin composition using a recycled resin in which a large amount of thermosetting materials such as metals, rubbers, paints, etc. are mixed, the black spots are not noticeable and the brightness is higher. Can be colored.

By coloring with a chromatic dye, the recycled resin can be colored with higher saturation than chromatic pigments. This is because the chromatic dye has higher coloring power and higher dispersibility than the chromatic pigment.

  By coloring the recycled resin with high saturation, the saturation of the black spot is felt high due to the assimilation phenomenon of the hue, and the black spot can be made inconspicuous.

  Furthermore, it is possible to color with a higher brightness than in the past without reducing the brightness adjusted by the addition of a white pigment having a concealing property. This is because the chromatic dye is different from the pigment and exists as a molecule in the molded product, and therefore has no light shielding property.

  On the other hand, when a chromatic pigment is used, since the chromatic pigment is present in a granular form in the molded body and has a concealing property, a part of the white pigment is also concealed, thereby reducing the brightness of the molded body. .

  The resin composition of the second invention is characterized in that, in the resin composition of the first invention, the chromatic dye is powdery. As a result, the recycled resin can be pelletized or the chromatic dye can be uniformly dispersed during injection molding, and coloring can be performed without increasing the number of steps.

  The resin composition of the third invention is characterized in that, in the resin composition of the first or second invention, the regenerated thermoplastic resin is composed of any one of polypropylene, ABS, and polystyrene. Thereby, it becomes possible to improve the recycling rate of waste home appliances.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment)
The resin composition for injection molding according to Embodiment 1 will be described.

  FIG. 1 is a sectional view of an injection molded product according to Embodiment 1 of the present invention, and FIG. 2 is a process diagram for obtaining an injection molded product.

  In FIG. 1, a resin molded product 1 is mainly composed of a recycled resin 2 serving as a base material, and foreign matter 3 causing black spots is mixed therein. Furthermore, it contains a white pigment 4 and a chromatic dye 5 for the purpose of toning. The chromatic dye 5 is dispersed in a molecular state in the molding pair and cannot be visually recognized, but is illustrated for explanation.

  Based on FIG. 2, the manufacturing method of the resin molded product 1 of this Embodiment 1 is demonstrated.

  First, a method for producing pellets of the recycled resin 2 will be described.

  A resin product is recovered from a product discarded after use by a predetermined method, pulverized, and sorted for each resin type by a predetermined method. At this time, the recovery method and sorting method of the recycled resin 2 of the present invention are not particularly specified and can be freely selected.

  Among the selected resin types, a pulverized product of the thermoplastic resin to be recycled is put into a hopper of an extruder. At this time, the recycled resin of the present invention is not particularly specified such as ABS, PS, PP, etc., and can be freely selected in consideration of the required appearance quality, mechanical properties, cost, and the like. At this time, in order to obtain predetermined physical properties, additives (dispersant, lubricant, etc.) may be added together with the pulverized resin at a predetermined ratio.

  The pulverized resin as the raw material of the recycled resin 2 falls into the groove of the screw, and is transferred in the nozzle direction while being melted and kneaded by the rotation of the screw. The resin transferred in the nozzle direction is discharged from the die attached with the nozzle. The resin discharged in the form of a thread from the small hole of the die is cooled in a water tank, and the cooled resin is cut into pellets by a pelletizer to obtain pellets of recycled resin 2.

  Next, injection molding will be described.

  The pellets of recycled resin 2 that has been dried to remove moisture are put into a hopper of an injection molding machine. At this time, if the thermoplastic resin as the recycled resin 2 is a material having low hygroscopicity, the drying step can be omitted. Moreover, you may mix unused resin with the reproduction | regeneration resin 2 in a predetermined ratio. The unused resin can be used without particular limitation as long as it is a thermoplastic resin that can be injection-molded. Specific examples include polyethylene, polypropylene, polystyrene, ABS, methyl methacrylate, polyamide, polyethylene terephthalate, polybutylene terephthalate, and chloride. Examples include vinyl, polylactic acid, and polyester.

  The recycled resin 2 is transferred in the nozzle direction while being melted and kneaded by rotation of the screw in the cylinder. With the mold closed, the recycled resin 2 is injected into the cavity of the mold. The recycled resin 2 is filled in the entire cavity of the mold, the mold is cooled, the recycled resin 2 filled in the mold is solidified, and finally the mold is opened to take out the resin molded product 1.

  At this time, in order to prevent defects such as sinks, welds, and burns from occurring on the surface of the resin molded product 1, various conditions such as mold temperature, cylinder temperature, injection speed, injection pressure, pressure holding time, and cooling time are set to recycled resin. Adjust as appropriate according to the type.

  In order to obtain a predetermined appearance, the mold to be used appropriately adjusts the abrasive type and the surface roughness after polishing. Moreover, you may give an embossing process.

  In the present embodiment, the coloring method of the recycled resin 2 is not particularly specified as a master batch, a dry color, or the like. For this reason, the white pigment having light-shielding property may be added in the process of regenerating the thermoplastic resin, or may be added in the process of injection molding. Similarly, the chromatic dye may be added in the process of regenerating the thermoplastic resin or in the process of injection molding, or by dissolving the dye in a solvent, it can be colored by immersion after injection molding. It is.

  In the injection molded product of the present invention, a white pigment and a chromatic dye can be used in order to obtain a desired color tone. However, the white pigment and the chromatic dye are not particularly specified and conventionally known. These materials can be used as appropriate.

  As the white pigment, a pigment having high concealability is desirable from the viewpoint of making black spots difficult to see. Specifically, as the white pigment, calcium carbonate, talc, kaolin clay, titanium oxide, zinc oxide, silica, calcium carbonate Conventionally known pigments can be freely selected, and can be used alone or in combination.

As the dye, natural dyes, synthetic dyes, fluorescent dyes and the like can be used alone or in combination. As a specific example, C.I. I. Acid Red 2, C.I. I. Azoic coupling components, C.I. I. Azoic diazo component 112, C.I. I. Ingle Yellow 1, C.I. I. Oxidation base 31, C.I. I. Sulfur Black 1, C.I. I. Jasper Blue 1, C.I. I. Solvent Yellow 34, C.I. I. Direct Red 28, C.I. I. Natural yellow 10, C.I. I. Fluorescent Brightener 41, C.I. I. Food Orange 5, C.I. I. Basic Violet 14, C.I. I. Molded Red 11, C.I. I. The reactive red 36 may be used, but is not limited thereto.

  In addition, pearlescent pigments that do not have concealability (such as mica coated with metal oxide, glass coated with metal oxide, etc.) can be freely selected from the required appearance, cost, etc. It is also possible to use a mixture of seeds.

  Furthermore, the injection molded product of the present invention may use a lubricant in order to control the fluidity of the recycled resin. The lubricant is not particularly specified. For example, hydrogen carbonate such as liquid paraffin and polyethylene wax, fatty acid such as stearic acid, aliphatic amide such as stearic acid amide and oleic acid amide, zinc stearate and magnesium stearate There may be a metal soap system such as, and a plurality of lubricants may be used in combination.

  In addition, the injection molded product of the present invention may use a dispersant for the purpose of dispersing the colorant and controlling the color development. The dispersant is not particularly specified, and may be appropriately selected depending on the type of resin and colorant used. Examples of the dispersant include synthetic waxes such as polyethylene wax and polypropylene wax, and natural waxes such as paraffin wax, and a plurality of dispersants may be used in combination.

  In addition, the recycled resin of the injection molded product of the present invention may contain a fibrous filler, an antioxidant, an ultraviolet absorber, a flame retardant, an antibacterial agent and the like according to the function to be imparted.

  The results of evaluating the quality of the resin molded product are shown in Tables 1 and 2.

  About the evaluation method of the quality of a resin molded product, sensory evaluation was performed with respect to the resin molded product (100 mm square, thickness 2 mm), and it judged by the following evaluation items.

OK (AA): Applicable to external parts (black spots are inconspicuous)
OK (A): Applicable to semi-appearance parts (black spots are inconspicuous but lightness is low)
NG (B): Not applicable to semi-appearance parts (black spots are conspicuous)
Here, the semi-appearance part is a resin that is placed in a place where it is difficult for the user to see when it is incorporated into the product. Refers to parts.

The main raw materials used in the examples or comparative examples are as follows.
<White pigment>
(1) Titanium oxide CR-60-2 (average particle size 0.21 micron) manufactured by Ishihara Sangyo Co., Ltd.
(2) Titanium oxide CR-60 (average particle size 0.21 micron) manufactured by Ishihara Sangyo Co., Ltd.
(3) Titanium oxide CR-63 (average particle size 0.21 micron) manufactured by Ishihara Sangyo Co., Ltd.
(4) Titanium oxide R-11P (average particle size 0.20 micron) manufactured by Sakai Chemical Co., Ltd.
(5) Titanium oxide R-21 manufactured by Sakai Chemical Co., Ltd. (average particle size 0.20 micron)
(6) Titanium oxide SR-1 manufactured by Sakai Chemical Co., Ltd. (average particle size 0.25 micron)
(7) Titanium oxide JR-403 (average particle size 0.25 microns)
(8) Titanium oxide JR-405 (average particle size 0.21 micron)
(9) New lime calcium carbonate PP-10 (average particle size 0.15 micron)
(10) New lime light calcium carbonate (average particle size 2 microns)
(11) New lime complex zinc oxide fine Z (average particle size 0.3 microns)
(12) Zinc oxide MZ-500 (average particle size 0.025 microns) manufactured by Teika
(13) Talc LMS-400 (average particle size 3.8 microns) manufactured by Fuji Talc
(14) Talc NK-48 manufactured by Fuji Talc (average particle size 21 microns)
<Chromatic dye>
(31) KP Plastic Yellow MK manufactured by Kiwa Chemical Industry Co., Ltd.
(32) KP Plastic Yellow 2G manufactured by Kiwa Chemical Industry Co., Ltd.
(33) KP Plastic Brilliant Red MG manufactured by Kiwa Chemical Industry Co., Ltd.
(34) KP Plastic Red H2G manufactured by Kiwa Chemical Industry Co., Ltd.
(35) KP Plastic Red 5B manufactured by Kiwa Chemical Industry Co., Ltd.
(36) KP Plastic Blue BR manufactured by Kiwa Chemical Industry Co., Ltd.
(37) KP Plastic P-Red 3RH manufactured by Kiwa Chemical Industry Co., Ltd.
<Recycled resin>
(41) Recycled PP resin made by Panasonic Ecology Center Co., Ltd. (42) Recycled ABS resin made by Panasonic Ecology Center Co., Ltd. (43) Recycled PS resin made by Panasonic Ecology Center Co., Ltd. <Unused thermoplastic resin>
(44) ABS / ASA resin EX18Z manufactured by UMG ABS
(45) ABS resin 250-X10 manufactured by Toray Industries, Inc.
(46) Prime polymer PP resin J-882HV
(47) PP resin BC06C made by Nippon Polypro
(48) PS Japan made PS resin 403R
<Chromatic pigments>
(51) SYMULER Brilliant Carmine 6B manufactured by DIC
(52) SYMULER Fast Yellow made by DIC
(53) FASTOGEN Blue made by DIC
The chromatic pigment was added in the same manner as the white pigment.
[Evaluation results of injection molded products]
Tables 1 and 2 show the configuration of the injection molded products (P1 to P36) and the evaluation results.
(1) to (53) described in the columns of “Recycled resin”, “Unused resin”, “White pigment A”, “Chromatic pigment B”, and “Chromatic dye C” in Table 1 are the numbers of the raw materials. Show. In the columns of “Recycled Resin” and “Unused Resin”, the numbers in parentheses indicate the composition ratio of the resin with the total amount being 10.

  Table 1 shows a case where the white pigment and the chromatic dye are added in a range where the total addition amount is 1.0 part by weight or more and 16.0 parts by weight or less. As shown in P <b> 1 to P <b> 18, the sensory evaluation result of the appearance quality of the molded body was “OK (AA): Applicable to appearance parts (black spots are not noticeable)”.

  Further, as can be seen from P3, P4, P7, P8, and P11 to 13, the recycled resin could be used without any trouble even if it was used in combination with an unused thermoplastic resin.

  Table 2 shows the case where the white pigment and the chromatic dye are added in a total amount of less than 1.0 part by weight or more than 16.0 parts by weight.

  As shown in Table 2, when both the white pigment and the chromatic dye are not used, and when the total amount added is less than 1.0 part by weight, the design deterioration due to the black spots becomes remarkable, as shown in P19 to P21 and P25 to P27. As described above, the sensory evaluation result of the appearance quality of the molded body was “NG (B): not applicable to semi-appearance parts (black spots are conspicuous)”.

  Further, when white pigments and chromatic pigments were used, as shown in P22 to P24, the design properties were not impaired by the black spots, but the brightness was relatively lowered. “OK (A): Applicable to semi-appearance parts (although black spots are inconspicuous but lightness is low)”.

  On the other hand, when the total addition amount of the white pigment and the chromatic dye is in the range of 16 parts by weight or more, as shown in P28 to P36, the sensory evaluation result of the appearance quality of the molded product is “OK (A): applicable to semi-appearance parts ( The sunspots are inconspicuous but the brightness is low). This is because the black spots were made inconspicuous, but the pigment was overfilled, leading to poor dispersion and uneven color.

As described above, the resin molded product using the recycled resin according to the present invention can obtain a high-lightness appearance quality equivalent to a resin molded product using an unused resin without being colored in black or low brightness. Even a recycled resin can be applied to external parts. For example, it can be used for home appliances such as a vacuum cleaner, a refrigerator, an air conditioner, a washing machine, a warm water washing toilet seat, a microwave oven, and a rice cooker.

1 resin molded product 2 recycled resin 3 foreign material 4 white pigment 5 chromatic dye

Claims (4)

A resin composition for injection molding, wherein a total amount of at least a white pigment and a chromatic dye is added to a recycled thermoplastic resin containing foreign substances in a range of 1.0 part by weight or more and 16.0 parts by weight or less. The resin composition for injection molding according to claim 1, wherein the chromatic dye is powdery. The resin composition for injection molding according to claim 1 or 2, wherein the chromatic dye is uniformly dispersed during pelletization of the recycled resin or during injection molding. The resin composition for injection molding according to any one of claims 1 to 3, wherein the regenerated thermoplastic resin is composed of any one of polypropylene, ABS, and polystyrene.