JP2012197357A - Expandable polystyrene-based colored resin particle and method of manufacturing the same, colored resin preliminary foamed particle, and colored resin expansion molding body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an expandable polystyrene-based colored resin particle that can easily manufacture an expansion molding body which is uniformly colored without irregular coloring, and to provide a method of manufacturing the same.SOLUTION: The expandable polystyrene-based colored resin particle tinted by a dye is characterized in that the volume average particle size of the dye is at most 35 μm. The method of manufacturing the expandable polystyrene-based colored resin particle in which a polystyrene resin particle is put in a pressure tight vessel and is impregnated with a dye and a foaming agent in the pressure tight vessel to manufacture the expandable polystyrene-based colored resin particle, is characterized in that the volume average particle size of the dye is at most 35 μm. The method of manufacturing the expandable polystyrene-based colored resin particle in which a foamable polystyrene based resin particle is put in the pressure tight vessel, and impregnated with a dye in the pressure tight vessel to manufacture the expandable polystyrene-based colored resin particle, is characterized in that the volume average particle size of the dye is below 35 μm.

Description

  The present invention relates to an expandable polystyrene-based colored resin particle comprising a foaming agent and comprising colored polystyrene-based resin particles, and a method for producing the same. Expandable polystyrene-based colored resin particles that can be easily produced, a method for producing the same, a colored resin pre-foamed particle obtained by foaming the colored resin particle, and obtained by foam-molding the colored resin pre-foamed particle The present invention relates to a colored resin foam molded article.

Polystyrene resin foam moldings are widely used as transport containers and packaging containers. Among them, for fresh fish and building materials, it is used for coloring purposes in order to distinguish it from other containers and to improve design.
For example, a foamed molded product colored in blue or purple for fresh fish and orange or green for building materials is used. On the other hand, since it has the advantage that dirt is not conspicuous if it is colored in gray, it is often colored in gray for use as a structural member.

  Conventionally, as a method for producing colored expandable resin particles, for example, in Patent Document 1 (Japanese Patent Laid-Open No. 6-157805), a thermoplastic resin particle is dispersed in an aqueous medium, and then a readily volatile foaming agent. In the method for producing colored foamable resin particles by impregnating with a dye, a dye having a maximum length of 300 μm or more and a content of 40% or less is dispersed in the aqueous medium. A method for producing resin particles is disclosed.

JP-A-6-157805

  However, as disclosed in Patent Document 1, even when a dye having a maximum length of 300 μm or more and a content of 40% or less is used, uneven coloring may occur.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an expandable polystyrene-based colored resin particle that can easily produce a foamed molded product that is uniformly colored and that is uniformly colored, and a method for producing the same.

  In order to solve the above-mentioned problems, the present invention provides an expandable polystyrene-based colored resin particle characterized in that, in an expandable polystyrene-based colored resin particle colored with a dye, the volume average particle diameter of the dye is 35 μm or less. provide.

  In the expandable polystyrene colored resin particles of the present invention, the dye is one or more selected from the group consisting of anthraquinone dyes, nitro dyes, azo dyes, acetanilide dyes, and quinoline dyes. Is preferred.

  The expandable polystyrene-based colored resin particles of the present invention may have a configuration in which a polyethylene-based resin is contained in the polystyrene-based resin particles.

  The present invention also provides a method for producing expandable polystyrene-based colored resin particles by placing polystyrene-based resin particles in a pressure-resistant container and impregnating the dye and the foaming agent in the pressure-resistant container, wherein the volume average particle diameter of the dye is 35 μm. Provided is a method for producing expandable polystyrene-based colored resin particles, which is characterized by the following.

  Further, the present invention provides a method for producing expandable polystyrene-based colored resin particles by placing expandable polystyrene-based resin particles in a pressure-resistant container and impregnating the dye in the pressure-resistant container, wherein the volume average particle diameter of the dye is 35 μm or less. A method for producing expandable polystyrene-based colored resin particles is provided.

  In the method for producing expandable polystyrene colored resin particles of the present invention, the dye is one or more selected from the group consisting of anthraquinone dyes, nitro dyes, azo dyes, acetanilide dyes, and quinoline dyes. It is preferable that

  In the method for producing expandable polystyrene colored resin particles of the present invention, the polystyrene resin particles may include a polyethylene resin.

  The present invention also provides colored resin pre-foamed particles obtained by heating and pre-foaming the expandable polystyrene-based colored resin particles according to the present invention.

  In addition, the present invention provides a colored resin foam molded article obtained by filling the colored resin pre-expanded particles according to the present invention into a cavity of a molding die and heating to form in-mold foam molding.

  Moreover, this invention provides the heat insulating material for building materials obtained by carrying out in-mold foam molding of the said colored resin pre-expanded particle which concerns on this invention.

  The present invention also provides a food container obtained by in-mold foam molding of the colored resin pre-expanded particles according to the present invention.

  The present invention also provides a transport container obtained by in-mold foam molding of the colored resin pre-expanded particles according to the present invention.

  The present invention also provides a cold insulated container obtained by in-mold foam molding of the colored resin pre-expanded particles according to the present invention.

  The present invention also provides a decorative block obtained by in-mold foam molding of the colored resin pre-expanded particles according to the present invention.

  The present invention also provides a civil engineering block obtained by in-mold foam molding of the colored resin pre-expanded particles according to the present invention.

  The expandable polystyrene colored resin particles of the present invention are uniformly colored with no uneven coloring because the volume average particle diameter of the dye is 35 μm or less in the expandable polystyrene colored resin particles colored with the dye. A foam-molded article can be easily produced.

  As described above, the method for producing expandable polystyrene-based colored resin particles of the present invention can easily and inexpensively produce expandable polystyrene-based colored resin particles from which a beautifully colored expanded molded article can be obtained.

(Expandable polystyrene colored resin particles)
The expandable polystyrene-based colored resin particles of the present invention are expandable polystyrene-based colored resin particles colored with a dye. In the expandable polystyrene-based colored resin particles colored with a dye, the volume average particle diameter of the dye is 35 μm or less. It is characterized by being.
In the present invention, the volume average particle diameter of the dye means a value measured by the following measuring method.

<Measurement method of volume average particle diameter of dye>
The volume average particle diameter is a value measured with Multisizer II (manufactured by Beckman Coulter). The measurement is carried out by performing calibration using a 50 μm aperture according to Reference MANUAL FOR THE COULTER MULTISIZER (1987) published by Coulter Electronics Limited.
Specifically, 0.1 g of a dye is predispersed in 10 ml of a 0.1% nonionic surfactant solution using a touch mixer and ultrasonic waves, and this is provided with an ISOTON II (manufactured by Beckman Coulter, Inc .: measurement) In a beaker filled with an electrolytic solution), dripping with a dropper while gently stirring, adjust the reading of the densitometer on the main body screen to about 10%. Next, when using an aperture size of 50 μm for the Multisizer II body, input Current as 800, Gain as 4, and Polarity as + (the aperture size can be changed as required) and measured manually. I do. During the measurement, the beaker is stirred gently to the extent that bubbles do not enter, and the measurement is terminated when 100,000 particles are measured.

As the polystyrene resin particles used for the expandable polystyrene colored resin particles of the present invention, for example, polystyrene resin particles obtained by the following production methods (1) to (4) can be used.
(1) A so-called suspension polymerization method in which a polymerizable monomer having a styrene monomer as a main component is dispersed in an aqueous suspension to perform polymerization to obtain polystyrene resin particles.
(2) After the polystyrene resin seed particles are dispersed in the aqueous suspension, the polymerizable monomer mainly containing a styrene monomer is absorbed into the seed particles to perform polymerization, and the polystyrene resin So-called seed polymerization method to obtain particles,
(3) A polystyrene resin is charged into an extruder and melted by heating. The polystyrene resin is extruded from the small holes of a die having a large number of small holes attached to the discharge side of the extruder, and immediately after that, cut in water. A so-called melt-extrusion underwater cutting method in which polystyrene resin particles are obtained by rapid cooling.
(4) A polystyrene resin is charged into an extruder and melted by heating. The polystyrene resin is extruded from the small holes of a die having a large number of small holes attached to the discharge side of the extruder, and then rapidly cooled in water and cooled. Strand cutting method of so-called melt extrusion method, in which polystyrene resin particles are obtained by cutting later.

Examples of the styrene monomer used in the above (1) suspension polymerization method and (2) seed polymerization method include styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, bromo. The main component is a styrene monomer such as styrene, and the styrene monomer is usually contained in an amount of 50% by mass or more, preferably 80% by mass or more. Of these styrene monomers, styrene is particularly preferable.
Further, the polymerizable monomer that can be used in combination with the styrene monomer is not particularly limited as long as it is copolymerizable with the styrene monomer, and divinylbenzene, alkylene glycol dimethacrylate, acrylonitrile, methyl methacrylate, and the like. Is mentioned.

(2) When producing expandable polystyrene resin particles by the seed polymerization method, the polystyrene resin particles obtained by the suspension polymerization method are used as seed particles, or the polystyrene resin is obtained in advance by an extruder. After adjusting to the diameter, it may be used as seed particles.
(2) When seed particles are produced using an extruder in the seed polymerization method, or (3) polystyrene resins used in the melt extrusion method are commercially available ordinary polystyrene resins, suspension polymerization methods, etc. In addition to using polystyrene resins that are not recycled materials (virgin polystyrene), such as newly produced polystyrene resins by the method, use recycled materials obtained by reprocessing used polystyrene resin foam moldings. Can do. Examples of this recycled material include recycled polystyrene resin foam molded products such as fish boxes, household appliance cushioning materials, food packaging trays, etc., and recycled by the limonene dissolution method or heating volume reduction method. It is done.

  The particle diameter of the expandable polystyrene resin particles is not particularly limited, but is usually about 0.3 to 2.0 mm from the viewpoint of filling of the pre-expanded particles into the mold cavity at the time of molding. 3-1.4 mm is preferable.

  In this invention, it is preferable that the weight average molecular weight (Mw) by GPC method is 170,000-700,000 as for the molecular weight of the polystyrene-type resin to be used. If the molecular weight of the polystyrene-based resin is less than 170,000, the strength of the foamed molded product finally obtained is lowered, and if it exceeds 700,000, it is difficult to obtain sufficient foamability, which is not preferable.

  The polymerization initiator used in the above (1) suspension polymerization method and (2) seed polymerization method is not particularly limited as long as it is usually used in suspension polymerization of styrene. For example, a radical generating polymerization initiator is used. Can be used. Specifically, benzoyl peroxide, lauryl peroxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxybenzoate, t-butylperoxy-2-ethylhexyl monocarbonate, t-butylperoxy Pivalate, t-butylperoxyisopropyl carbonate, t-butylperoxyacetate, 2,2-t-butylperoxybutane, t-butylperoxy-3,3,5-trimethylhexanoate, di-t- Examples thereof include organic peroxides such as butyl peroxyhexahydroterephthalate and azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile. These polymerization initiators can be used alone or in combination of two or more.

In the polymerization described above, in order to reduce the styrene monomer remaining in the polystyrene resin particles, it is preferable to use a high temperature decomposition type polymerization initiator and set the final polymerization temperature to 115 ° C. or higher. Examples of the high-temperature decomposition type polymerization initiator include t-butyl peroxybenzoate, t-butyl peroxy-2-ethylhexyl monocarbonate, t-butyl peroxypivalate, t-butyl peroxyisopropyl carbonate, and t-butyl peroxybenzene. Examples include oxyacetate and 2,2-t-butylperoxybutane having a temperature of 100 to 115 ° C. for obtaining a half-life of 10 hours. An excessive addition of a high temperature decomposition type polymerization initiator is not preferable because alcohols as decomposition byproducts are generated.
In the polymerization, the decomposition temperature for obtaining a half-life of 10 hours is in the range of 80 to 120 ° C. in terms of adjusting the molecular weight of the polystyrene resin particles and reducing the residual amount of monomer. It is preferable to use a combination of two or more polymerization initiators.

In carrying out the (1) suspension polymerization or (2) seed polymerization, a suspending agent may be used to disperse styrene monomer droplets or seed particles in an aqueous medium. Examples of the suspending agent include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, polyacrylamide, and polyvinyl pyrrolidone, and poorly water-soluble inorganic compounds such as tricalcium phosphate and magnesium pyrophosphate. In addition, when using a slightly water-soluble inorganic compound, it is preferable to use an anionic surfactant together.
Examples of the anionic surfactant include fatty acid soaps, N-acyl amino acids or salts thereof, carboxylates such as alkyl ether carboxylates, alkylbenzenesulfonates, alkylnaphthalenesulfonates, dialkylsulfosuccinates, alkylsulfates. Sulfates such as acetates and α-olefin sulfonates; sulfates such as higher alcohol sulfates, secondary higher alcohol sulfates, alkyl ether sulfates, polyoxyethylene alkylphenyl ether sulfates; alkyls And phosphoric acid ester salts such as ether phosphoric acid ester salts and alkyl phosphoric acid ester salts. Expandable polystyrene resin particles can be produced by impregnating the polystyrene resin particles obtained as described above with a foaming agent and a plasticizer by a suspension polymerization impregnation method or a post-impregnation method.

In the expandable polystyrene-based colored resin particles of the present invention, the dye is not particularly limited as long as the volume average particle diameter of the dye is 35 μm or less, but for coloring a synthetic resin foam such as a polystyrene-based resin foam. Various kinds of dyes conventionally used can be used, and one or more selected from the group consisting of anthraquinone dyes, nitro dyes, azo dyes, acetanilide dyes, and quinoline dyes It is preferable.
The anthraquinone dyes, SolventBlue35 (COLOR INDEX GENERIC NAME, hereinafter the same), SolventBlue36, SolventBlue78, SolventBlue87, DisperseRed11, DisperseRed15, DisperseRed153, DisperseBlue1, DisperseBlue3, DisperseBlue7, DisperseBlue26, DisperseBlue35, SolventRed111, SolventRed146 the like.
Examples of the nitro dye include Disperse Yellow 1 and Disperse Yellow 9.
Examples of the azo dye include Disperse Yellow 4, Disperse Orange 1, Disperse Orange 3, Disperse Orange 13, Disperse Orange 37, Disperse Red 1, Disperse Red 17, Dispse Red 85, Dispse 85, Dispse 85, Dispse 85, Dispse 85, Dispse 85, Dispse Orange 85
Examples of acetanilide dyes include Disperse Blue 165, Disperse Blue 79, Disperse Red 82, Disperse Red 152, Disperse Red 167, Disperse Red 277, Disperse Yellow 3, and the like.
Examples of quinoline dyes include Disperse Yellow 54 and Disperse Yellow 64.
These dyes may be used alone. Two or more of the same color dyes may be used in combination. Furthermore, different color dyes may be used in combination and colored in a mixed color.

  The content of the dye is preferably in the range of 0.003 to 0.5 mass% in the polystyrene-based resin, and more preferably in the range of 0.005 to 0.30 mass%. If the content of the dye is less than the above range, the degree of coloration of the foamed molded product finally obtained will be weak. On the other hand, if the content of the dye exceeds the above range, it is not preferable because not only the cost increases but also the moldability decreases.

  The volume average particle diameter of the dye is 35 μm or less, preferably 30 μm or less, and more preferably 25 μm or less. When the volume average particle diameter of the dye exceeds 35 μm, uneven coloring occurs in the foamed molded product produced using the expandable polystyrene-based colored resin particles. The volume average particle diameter of the dye can be adjusted to a desired volume average particle diameter by pulverizing the dye by a dry pulverization method or a wet pulverization method.

  The dye preferably does not substantially contain crystals having a maximum particle size of 300 μm or more, and more preferably does not contain crystals having a maximum length of 300 μm or more.

  Examples of the foaming agent used in the expandable polystyrene-based colored resin particles of the present invention include aliphatic hydrocarbons having 5 or less carbon atoms used for the production of general thermoplastic resin foams, such as n-butane, isobutane, n -Pentane, isopentane, neopentane, etc. are mentioned, 1 type may be used independently and 2 or more types may be used together.

  The content of the foaming agent is preferably in the range of 2 to 10% by mass, more preferably 3 to 9% by mass with respect to the polystyrene resin particles. When the content is less than 2% by mass, not only is it difficult to reduce the density, but the effect of increasing the secondary foaming power at the time of molding cannot be obtained, so that the appearance of the foamed molded product becomes inferior. On the other hand, if the content exceeds 10% by mass, the shrinkage during foam molding, the adjustment time of the residual gas in the pre-expanded particles is delayed, and the molding cycle becomes long, which is not preferable from the viewpoint of productivity.

  The expandable polystyrene-based colored resin particles are used in the production of expandable polystyrene-based resin particles in the range that does not impair the physical properties, and are conventionally used for the production of foam nucleating agents, plasticizers, fillers, flame retardants, flame retardant aids. You may use an agent, a lubricant, etc. suitably as needed. Also, if powdered metal soaps such as zinc stearate are coated on the surface of the expandable polystyrene-based colored resin particles, the bonding between the pre-expanded particles is reduced in the pre-expanding step of the expandable polystyrene-based colored resin particles. This is preferable. In addition, a general-purpose coating agent may be appropriately used as necessary, and examples thereof include stearic acid triglyceride, stearic acid monoglyceride, castor oil, amide compound, silicon, and polyethylene glycol.

  The expandable polystyrene colored resin particles of the present invention may have a configuration in which a polyethylene resin is contained in the polystyrene resin particles. The ratio of the polyethylene resin in the polystyrene resin particles is preferably less than 50% by mass and more preferably in the range of 1 to 40% by mass. In order to contain the polyethylene resin in the polystyrene resin particles, for example, in the seed polymerization method (2) described in the method for producing the polystyrene resin particles, seed particles made of the polyethylene resin are used, and an aqueous suspension is used. Obtained by a method of dispersing polystyrene-based resin seed particles in the liquid, and then absorbing the polymerizable monomer mainly composed of a styrene-based monomer into the seed particles to perform polymerization to obtain polystyrene-based resin particles. be able to.

  The expandable polystyrene colored resin particles of the present invention are uniformly colored with no uneven coloring because the volume average particle diameter of the dye is 35 μm or less in the expandable polystyrene colored resin particles colored with the dye. A foam-molded article can be easily produced.

(Method for producing expandable polystyrene-based colored resin particles)
The expandable polystyrene colored resin particles according to the present invention can be produced by the following production method (A) or (B).

(A) In a method for producing expandable polystyrene-based colored resin particles by placing polystyrene-based resin particles in a pressure-resistant container and impregnating the dye and the foaming agent in the pressure-resistant container, a dye having a volume average particle diameter of 35 μm or less is used. A method for producing expandable polystyrene-based colored resin particles.

(B) Foaming using a dye having a volume average particle diameter of 35 μm or less in a method for producing expandable polystyrene colored resin particles by placing expandable polystyrene resin particles in a pressure resistant container and impregnating the dye in the pressure resistant container. For producing conductive polystyrene-based colored resin particles.

When purchasing and using a commercial item, the said dye performs the process which grind | pulverizes the commercial item dye and makes the volume average particle diameter 35 micrometers or less.
The pulverization of the dye is preferably dry pulverization, and a general-purpose pulverizer can be used. General-purpose pulverizers include hammer mill pulverizers, pin pulverizers, impact pulverizers, valpelizers, jet mill pulverizers, etc., combining single or multiple pulverizers depending on the desired volume average particle size. Smash.

In the production method of the present invention, the polystyrene resin particles or the expandable polystyrene resin particles are preferably dispersed in an aqueous medium containing a dispersant.
Examples of the dispersant include poorly water-soluble inorganic compounds such as magnesium pyrophosphate and tricalcium phosphate, and water-soluble polymers such as polyvinyl alcohol, methyl cellulose, polyacrylamide, and polyvinyl pyrrolidone.

The dye is desirably pulverized to a volume average particle size of 35 μm or less and then uniformly suspended in an aqueous medium containing a surfactant.
The surfactant used when dispersing the dye in an aqueous medium is selected from among anionic surfactants, cationic surfactants, amphoteric surfactants and nonionic surfactants. It can be appropriately selected and used in consideration of dispersibility and the like.

  As described above, the method for producing expandable polystyrene-based colored resin particles of the present invention can easily and inexpensively produce expandable polystyrene-based colored resin particles from which a beautifully colored expanded molded article can be obtained.

(Colored resin pre-expanded particles and colored resin foam molded article)
The expandable polystyrene-based colored resin particles of the present invention are pre-foamed by heating by steam heating or the like using a well-known apparatus and method in the field of producing foamed resin moldings, and are colored resin pre-foamed particles (hereinafter referred to as pre-foamed particles). ). The pre-expanded particles are pre-expanded so as to have a bulk density equivalent to the density of a colored resin foam-molded product to be manufactured (hereinafter referred to as a foam-molded product). In the present invention, its bulk density is not limited, usually in the range of 0.010~0.10g / cm ^3, preferably in the range of 0.015~0.050g / cm ^3.

In the present invention, the bulk density of the pre-expanded particles refers to those measured in accordance with JIS K6911: 1995 “General Test Method for Thermosetting Plastics”.
<Bulk density of pre-expanded particles>
Fill the graduated cylinder with pre-expanded particles to a scale of 500 cm ³ . However, the graduated cylinder is visually observed from the horizontal direction, and if at least one pre-expanded particle reaches the scale of 500 cm ³ , the filling is finished. Next, the mass of the pre-expanded particles filled in the graduated cylinder is weighed with two significant figures after the decimal point, and the mass is defined as W (g). The bulk density of the pre-expanded particles is calculated by the following formula.
Bulk density (g / cm ³ ) = W / 500

<Bulk expansion ratio of pre-expanded particles>
Moreover, the bulk expansion ratio of the pre-expanded particles is a numerical value calculated by the following equation.
Bulk foaming factor = 1 / bulk density (g / cm ³ )

The pre-expanded particles are filled in the cavity of the mold using a well-known apparatus and method in the field of manufacturing a foamed resin molded body, heated by steam heating or the like, and subjected to in-mold foam molding, foaming A molded body is manufactured.
Although the density of the foamed molded article of the present invention is not particularly limited, usually in the range of 0.010~0.10g / cm ^3, preferably in the range of 0.015~0.050g / cm ^3.
This foamed molded product can be used, for example, as a building material heat insulating material, a food container, a transport container, a cold insulation heat insulating container, a decorative block, a transport container, a civil engineering block, and the like.

In the present invention, the density of the foamed molded product refers to the density of the foamed molded product measured by the method described in JIS K7122: 1999 “Measurement of foamed plastic and rubber-apparent density”.
<Density of foam molding>
A test piece of 50 cm ³ or more was cut so as not to change the original cell structure of the material, its mass was measured, and calculated according to the following formula.
Density (g / cm ³ ) = Test piece mass (g) / Test piece volume (cm ³ )
Test specimen condition adjustment and measurement specimens were cut from a sample that had passed 72 hours or more after molding, and were subjected to atmospheric conditions of 23 ° C ± 2 ° C x 50% ± 5% or 27 ° C ± 2 ° C x 65% ± 5%. It has been left for more than an hour.

<Folding multiple of foamed molded product>
Further, the expansion factor of the foamed molded product is a numerical value calculated by the following equation.
Foaming factor = 1 / density (g / cm ³ )

  The foamed molded product of the present invention was obtained by heating and pre-expanding the expandable polystyrene-based colored resin particles, filling the obtained pre-expanded particles in a cavity of a mold, and heating and in-mold foam molding. Therefore, it is possible to provide a foamed molded article having a beautiful appearance with uniform coloring and no uneven coloring.

[Example 1]
(Preparation of polystyrene resin particles (seed particles))
An autoclave with a stirrer having an internal volume of 100 liters (hereinafter also referred to as a reactor) 120 g of tricalcium phosphate (manufactured by Ohira Chemical Co., Ltd.), 4 g of sodium dodecylbenzenesulfonate, 140 g of benzoyl peroxide (purity 75%), t-butyl per After charging 30 g of oxy-2-ethylhexyl monocarbonate, 40 kg of ion exchange water and 40 kg of styrene monomer, the mixture was dissolved and dispersed under stirring at 100 rpm to form a suspension.
Subsequently, the temperature in the autoclave was raised to 90 ° C. while stirring at 100 rpm, and then held at 90 ° C. for 6 hours.
After that, the temperature inside the autoclave is further raised to 120 ° C. and held at 120 ° C. for 2 hours, then the temperature inside the autoclave is cooled to 25 ° C., the contents are taken out from the autoclave, dehydrated, dried and classified. Polystyrene resin particles (seed particles) having a diameter of 0.5 to 0.7 mm and a weight average molecular weight of 300,000 were obtained.

(Preparation of polystyrene resin particles)
In an autoclave with a stirrer having an internal volume of 100 liters, 11 kg of polystyrene resin particles (hereinafter also referred to as “seed particles”) having a particle size of 0.5 to 0.7 mm and a weight average molecular weight of 300,000, distilled water 32 kg, pyrroline 120 g of magnesium acid and 10 g of sodium dodecylbenzenesulfonate were added and stirred and suspended.
Next, 3000 g of distilled water, 20 g of magnesium pyrophosphate, 3 g of sodium dodecylbenzenesulfonate and 220 g of styrene were stirred with a homomixer to prepare a suspension, and this suspension was added to a reactor maintained at 75 ° C. The seed particles were allowed to absorb styrene for 15 minutes.
Subsequently, a suspension prepared by dissolving 160 g of benzoyl peroxide having a purity of 75% and 10 g of t-butylperoxy-2-ethylhexyl monocarbonate in 1860 g of styrene as a polymerization initiator and stirring with a homomixer with 2000 g of distilled water. Was added to the reactor maintained at 75 ° C.
After maintaining the temperature in the reactor at 75 ° C. for 25 minutes from the start of adding the suspension containing the polymerization initiator to the reactor, 31.42 kg of styrene was continuously introduced into the reactor at a rate of 11.8 kg / hr. The temperature inside the reactor was continuously raised so that the temperature would be 108 ° C. at the end of the styrene supply.
Subsequently, the temperature was raised to 120 ° C. and held for 30 minutes, then cooled to 20 ° C., taken out, washed, dehydrated and dried. Next, polystyrene resin particles having a median diameter of 0.85 mm and a weight average molecular weight of 310,000 were obtained except for coalesced particles that did not pass through the JIS 1180 μm sieve and powder particles that passed through the JIS 500 μm sieve.

(Preparation of expandable polystyrene colored resin particles)
A mixture of 2100 g of pure water, 5 g of magnesium pyrophosphate, and 1.4 g of sodium dodecylbenzenesulfonate is added to an autoclave equipped with a stirrer with an internal volume of 6 liters, and 45 g of cyclohexane is added as a plasticizer, followed by stirring with a homomixer. Was prepared. 2100 g of the polystyrene resin particles having the median diameter of 0.85 mm and the weight average molecular weight of 310,000 were added to the liquid, stirred at a rotational speed of 250 rpm, and held at 30 ° C. for 30 minutes.
Next, 4 g of the blue dye Solvent Blue 35 (volume average particle diameter 7.8 μm), 0.2 g of sodium dodecylbenzenesulfonate, and 100 g of pure water were charged into the autoclave, and the interior of the autoclave was heated to 90 ° C. over 30 minutes. The temperature rose. Thereafter, 180 g of butane (product name: butane silver, manufactured by Cosmo Oil Co., Ltd.) was press-fitted into the autoclave.
It was kept at 90 ° C. for 5 hours, then cooled to 25 ° C., taken out, washed, dehydrated and dried to obtain expandable polystyrene colored resin particles.

(Coating of expandable polystyrene colored resin particles)
5 kg of the expandable polystyrene-based colored resin particles obtained in this manner were put into a Ladige mixer M20 type (internal volume 20 liters) manufactured by Matsuzaka Trading Co., Ltd. Next, 2.5 g of zinc stearate, 2.5 g of 12-hydroxystearic acid triglyceride, and 2.5 g of stearic acid monoglyceride were sequentially added and stirred at 230 rpm for 3 minutes. Next, 2.5 g of polyethylene glycol having a weight average molecular weight of 300 was added and stirred at 230 rpm for 5 minutes to coat the resin particle surfaces.

(Preparation of pre-expanded particles)
The expanded polystyrene colored resin particles after coating are put into a small batch type pre-foaming machine having an internal volume of 40 liters, heated under normal pressure with water vapor with a gauge pressure of 0.05 MPa, and pre-foamed to a bulk foaming factor of 60 times, Pre-expanded particles were obtained.

(Manufacture of foam molding)
The obtained pre-expanded particles were left at 20 ° C. for 24 hours, dried and aged, and then a die having a cavity for manufacturing a plate-shaped molded article having an outer dimension of 300 × 400 × 25 mm was attached. It was attached to a molding machine, the pre-expanded particles were filled into the cavity, and in-mold foam molding was performed by steam heating. The molding machine is ACE-3SP manufactured by Sekisui Koki Seisakusho, with a gauge pressure of 0.7 kg / cm 2 in the QS molding mode, mold heating for 3 seconds, one heating for 8 seconds, reverse one heating for 1 second, double-side heating for 10 seconds, In-mold foam molding was carried out under conditions of water cooling for 5 seconds and a set extraction surface pressure of 0.02 MPa to produce a foam molded article.

In the production of the expandable polystyrene-based colored resin particles, the used dye (SolventBlue 35) was a dry product obtained by dry-grinding a commercial product to have a volume average particle diameter of 7.8 μm. This volume average particle diameter is a value measured as described in the above <Method for measuring volume average particle diameter of dye>.
Further, the dye used was measured for the maximum length in accordance with the following <Method for Measuring the Maximum Length of Dye>, and the ratio (%) of crystals having a maximum length of 300 μm or more was examined. The results are shown in Table 1.

  The obtained foamed molded product was placed in a drying chamber at 40 ° C. and dried for one day. The appearance was visually examined and evaluated based on the following evaluation of uneven coloring. The results are shown in Table 1. The obtained foamed molded article was of a good quality with foamed particles that fused well with each other, beautiful blue, and less uneven coloring.

<Measurement method of maximum length of dye>
For the maximum length of the dye, 0.15 g of the dye was predispersed in 10 ml of a 0.1% nonionic surfactant solution using a touch mixer and ultrasonic waves, and a microscope (manufactured by VHX-S50 KEYENCE) was used. The image was taken at three places with a magnification of 200 times and different places. The photos show dye crystals, and the maximum length of each of the crystals in the three photos was measured.

<Evaluation of uneven coloring>
The foamed molded product was visually confirmed, and the number of foamed particles in which coloring unevenness occurred within the main surface (400 × 300 mm) of the plate mold product was examined.
That is, the number of foamed particles with uneven coloring in the main surface is 3 or less, and the uniformly colored state throughout is regarded as no coloring unevenness (good appearance (（)), and within the main surface Although there were 3 or less foamed particles with uneven coloring, those having a color shade or color omission that could be judged to be acceptable in actual use were evaluated as acceptable (O). Furthermore, when there were 3 or more foamed particles with uneven coloring in the main surface, or when the color shading, color omission, etc. were severe, it was evaluated that there was uneven coloring (appearance defect (x)).

[Example 2]
A foam molded article was produced in the same manner as in Example 1 except that the blue dye was Solvent Blue 35 (volume average particle diameter 4.8 μm). About the used dye and the obtained foaming molding, the measurement and evaluation similar to Example 1 were performed. The results are shown in Table 1.

[Example 3]
A foam molded article was produced in the same manner as in Example 1 except that the blue dye was Solvent Blue 35 (volume average particle diameter 14.9 μm). About the used dye and the obtained foaming molding, the measurement and evaluation similar to Example 1 were performed. The results are shown in Table 1.

[Example 4]
A foam molded article was produced in the same manner as in Example 1 except that the blue dye was Solvent Blue 35 (volume average particle diameter 26.6 μm). About the used dye and the obtained foaming molding, the measurement and evaluation similar to Example 1 were performed. The results are shown in Table 1.

[Example 5]
A foam molded article was produced in the same manner as in Example 1 except that the blue dye was Solvent Blue 36 (volume average particle size 5.5 μm). About the used dye and the obtained foaming molding, the measurement and evaluation similar to Example 1 were performed. The results are shown in Table 1.

[Example 6]
A foam molded article was produced in the same manner as in Example 1 except that the blue dye was Solvent Blue 78 (volume average particle diameter 7.0 μm). About the used dye and the obtained foaming molding, the measurement and evaluation similar to Example 1 were performed. The results are shown in Table 1.

[Example 7]
Except that the blue dye was DisperseBlue 165 (volume average particle diameter 33.6 μm), the same procedure as in Example 1 was carried out to produce a foam molded article. About the used dye and the obtained foaming molding, the measurement and evaluation similar to Example 1 were performed. The results are shown in Table 1.

[Example 8]
(Manufacture of polyethylene modified styrene resin particles)
Ethylene / vinyl acetate copolymer resin particles (manufactured by Nippon Polyethylene Co., Ltd., LV-115) were heated with an extruder and pelletized by an underwater cutting method (ethylene / vinyl acetate copolymer resin particles were 80 mg per 100 particles). It was adjusted). 10.5 kg of the ethylene / vinyl acetate copolymer resin particles are placed in a 100-liter autoclave with a stirrer, and 45 kg of pure water as an aqueous medium, 315 g of magnesium pyrophosphate, and 1.6 g of sodium dodecylbenzenesulfonate are added and stirred to form an aqueous medium. It was suspended in and held for 10 minutes, and then heated to 60 ° C.
Next, 4.5 kg of styrene monomer in which 5.4 g of dicumyl peroxide was dissolved in this suspension was added dropwise over 30 minutes. After dropping, the mixture was kept at 60 ° C. for 30 minutes to allow the ethylene / vinyl acetate copolymer resin particles to absorb the styrene monomer. After absorption, the temperature was raised to 130 ° C., and stirring was continued at this temperature for 1 hour and 45 minutes. Thereafter, the temperature was lowered to 90 ° C., 11.4 g of sodium dodecylbenzenesulfonate was added to this suspension, and then 39.2 g of benzoyl peroxide and 4.9 g of t-butylperoxybenzoate were used as polymerization initiators. 6.2 kg of styrene monomer in which 98.7 g of dicumyl peroxide as a crosslinking agent was dissolved was dropped over 2 hours. Subsequently, 13.8 kg of a styrene monomer in which 175 g of ethylenebisstearic acid amide was dissolved was dropped over 2 hours. After completion of the dropping, the temperature was maintained at 90 ° C. for 1 hour, then heated to 143 ° C. and maintained at that temperature for 2 hours to complete the polymerization. Then, it cooled and taken out to normal temperature, wash | cleaned, spin-dry | dehydrated, and dried and obtained the polyethylene modified styrene-type resin particle.

(Expandable polyethylene modified styrene colored resin particles)
Subsequently, 15 kg of the above polyethylene-modified styrene resin particles were charged into a pressure-resistant rotary mixer having an internal volume of 50 L. Next, a mixed dispersion of 3 g of blue dye Solvent Blue 35 (volume average particle diameter 7.8 μm), 22.5 g of resist PE132 (Daiichi Kogyo Seiyaku Co., Ltd.) and 300 g of pure water was put into a mixer and rotated for 90 minutes. 405 g of cyclohexane and 1950 g of butane (product name: butane silver, manufactured by Cosmo Oil Co., Ltd.) were press-fitted and rotated for 10 minutes. Next, the temperature was raised to 70 ° C., and the rotation was continued at this temperature for 3 hours. Then, it cooled to normal temperature and took out the expandable polyethylene modified styrene-type colored resin particle.

  Thereafter, pre-foaming and in-mold foam molding were performed in the same manner as in Example 1 except that the bulk foaming factor was set to 30 times to produce a foam molded article. About the used dye and the obtained foaming molding, the measurement and evaluation similar to Example 1 were performed. The results are shown in Table 1.

[Example 9]
(Preparation of expandable polystyrene colored resin particles)
A mixture of 2100 g of pure water, 5 g of magnesium pyrophosphate, and 1.4 g of sodium dodecylbenzenesulfonate is added to an autoclave equipped with a stirrer with an internal volume of 6 liters, and 45 g of cyclohexane is added as a plasticizer, followed by stirring with a homomixer. Was prepared. Furthermore, 2100 g of polystyrene resin particles having a median diameter of 0.85 mm and a weight average molecular weight of 310,000 obtained in Example 1 were added, and stirring was started at a rotational speed of 250 rpm.
Next, the temperature inside the autoclave was raised to 90 ° C. over 30 minutes. Thereafter, 180 g of butane (product name: butane silver, manufactured by Cosmo Oil Co., Ltd.) was press-fitted into the autoclave.
It was kept at 90 ° C. for 5 hours, then cooled to 25 ° C., taken out, washed, dehydrated and dried to obtain expandable polystyrene resin particles.
Next, a mixture of 2100 g of pure water, 5 g of magnesium pyrophosphate, and 1.4 g of sodium dodecylbenzenesulfonate was added to an autoclave with a stirrer having an internal volume of 6 liters, and 45 g of cyclohexane was further added as a plasticizer and stirred with a homomixer. A suspension was prepared. Furthermore, 2100 g of the above expandable polystyrene resin particles were added, and after substitution with nitrogen, the mixture was stirred at a rotational speed of 250 rpm for 30 minutes.
Next, 4 g of the blue dye Solvent Blue 35 (volume average particle diameter 7.8 μm), 0.2 g of sodium dodecylbenzenesulfonate, and 100 g of pure water were charged into the autoclave, and the interior of the autoclave was heated to 60 ° C. over 30 minutes. The temperature rose. Thereafter, 30 g of butane (product name: butane silver, manufactured by Cosmo Oil Co., Ltd.) was press-fitted into the autoclave as a foaming agent.
It was kept at 60 ° C. for 2 hours, then cooled to 25 ° C., taken out, washed, dehydrated and dried to obtain expandable polystyrene colored resin particles.

  Thereafter, pre-foaming and in-mold foam molding were performed in the same manner as in Example 1 to produce a foam molded article. About the used dye and the obtained foaming molding, the measurement and evaluation similar to Example 1 were performed. The results are shown in Table 1.

[Example 10]
1000 g of the expandable polystyrene resin particles produced in Example 9 was put into a pressure-resistant rotary mixer having an internal volume of 5 L. Next, 0.2 g of blue dye Solvent Blue 35 (volume average particle size 7.8 μm) was charged into the mixer and rotated for 30 minutes, and then 30 g of pentane (product name: pentane manufactured by Cosmo Oil Co., Ltd.) was injected and rotated for 10 minutes. . Next, the temperature was raised to 40 ° C., and the rotation was continued at this temperature for 2 hours. Then, it cooled to 25 degreeC and took out the expandable polystyrene-type colored resin particle.
Thereafter, pre-foaming and in-mold foam molding were performed in the same manner as in Example 1 to produce a foam molded article. About the used dye and the obtained foaming molding, the measurement and evaluation similar to Example 1 were performed. The results are shown in Table 1.

[Comparative Example 1]
A foam molded article was produced in the same manner as in Example 1 except that the blue dye was Solvent Blue 35 (volume average particle diameter 42.6 μm). About the used dye and the obtained foaming molding, the measurement and evaluation similar to Example 1 were performed. The results are shown in Table 1.

[Comparative Example 2]
A foam molded article was produced in the same manner as in Example 1 except that the blue dye was Solvent Blue 35 (volume average particle diameter 36.8 μm). About the used dye and the obtained foaming molding, the measurement and evaluation similar to Example 1 were performed. The results are shown in Table 1.

[Comparative Example 3]
A foam molded article was produced in the same manner as in Example 1 except that the blue dye was Solvent Blue 87 (volume average particle diameter 39.1 μm). About the used dye and the obtained foaming molding, the measurement and evaluation similar to Example 1 were performed. The results are shown in Table 1.

[Comparative Example 4]
A foam molded article was produced in the same manner as in Example 1 except that the blue dye was Solvent Blue 58 (volume average particle diameter 54.4 μm). About the used dye and the obtained foaming molding, the measurement and evaluation similar to Example 1 were performed. The results are shown in Table 1.

From the results of Table 1, in Examples 1 to 10 according to the present invention, by using a dye having a volume average particle diameter of 35 μm or less, the obtained foamed molded article was fused well with each other. It was a beautiful blue color with little uneven coloring.
In particular, Examples 1, 2, 3, 5, 6, 8, 9, and 10 using dyes having a volume average particle diameter of 25 μm or less were excellent in appearance (◎) in the evaluation of coloring unevenness.
In the dyes used in Examples 1 to 10 and Comparative Examples 1 to 4, the ratio of crystals having a maximum length of 300 μm or more was all 0%.

  On the other hand, in the foamed molded products obtained in Comparative Examples 1 to 4 using a dye having a volume average particle diameter of more than 35 μm, the foamed particles are well fused with each other, but the coloring unevenness compared with the Examples. The appearance was inferior.

  The present invention relates to a foamable polystyrene-based colored resin particle comprising a foaming agent and comprising colored polystyrene-based resin particles and a method for producing the same, and in particular, easily producing a foamed molded product that is uniformly colored without uneven coloring. An expandable polystyrene colored resin particle that can be produced and a method for producing the same. The present invention also provides pre-foamed particles obtained by pre-foaming the expandable polystyrene-based colored resin particles, and foam-molded products obtained by in-mold foam molding of the pre-foamed particles. This foamed molded product can be used, for example, as a building material heat insulating material, a food container, a transport container, a cold insulation heat insulating container, a decorative block, a transport container, a civil engineering block, and the like.

Claims (15)

In expandable polystyrene colored resin particles colored with a dye,
Expandable polystyrene-based colored resin particles, wherein the dye has a volume average particle diameter of 35 μm or less.   The foaming property according to claim 1, wherein the dye is one or more selected from the group consisting of anthraquinone dyes, nitro dyes, azo dyes, acetanilide dyes, and quinoline dyes. Polystyrene colored resin particles.   The expandable polystyrene-based colored resin particles according to claim 1 or 2, wherein the polystyrene-based resin particles contain a polyethylene-based resin. In a method for producing expandable polystyrene-based colored resin particles by placing polystyrene-based resin particles in a pressure-resistant container and impregnating a dye and a foaming agent in the pressure-resistant container,
The method for producing expandable polystyrene colored resin particles, wherein the dye has a volume average particle diameter of 35 μm or less. In a method for producing expandable polystyrene-based colored resin particles by placing expandable polystyrene-based resin particles in a pressure-resistant container and impregnating the dye in the pressure-resistant container,
The method for producing expandable polystyrene colored resin particles, wherein the dye has a volume average particle diameter of 35 μm or less.   6. The dye according to claim 4, wherein the dye is one or more selected from the group consisting of anthraquinone dyes, nitro dyes, azo dyes, acetanilide dyes, and quinoline dyes. A method for producing expandable polystyrene-based colored resin particles.   The method for producing expandable polystyrene colored resin particles according to any one of claims 4 to 6, wherein a polyethylene resin is contained in the polystyrene resin particles.   Colored resin pre-expanded particles obtained by heating and pre-expanding the expandable polystyrene-based colored resin particles according to any one of claims 1 to 3.   A colored resin foam-molded product obtained by filling the colored resin pre-expanded particles according to claim 8 into a cavity of a molding die and heating to form in-mold foam molding.   A heat insulating material for building materials obtained by in-mold foam molding of the colored resin pre-expanded particles according to claim 8.   A food container obtained by in-mold foam molding of the colored resin pre-expanded particles according to claim 8.   A transport container obtained by in-mold foam molding of the colored resin pre-expanded particles according to claim 8.   A cold insulated heat insulating container obtained by in-mold foam molding of the colored resin pre-expanded particles according to claim 8.   A decorative block obtained by in-mold foam molding of the colored resin pre-expanded particles according to claim 8.   A civil engineering block obtained by in-mold foam molding of the colored resin pre-expanded particles according to claim 8.