JP2012214551A - Composite resin particle, foamable composite resin particle, preliminarily foamed particle, and foamed molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide composite resin particles which can give a foamed molding having a high multiple and excellent in impact resistance.SOLUTION: The composite resin particles are characterized by including 100 pts.mass of a polyethylene-based resin and 200-900 pts.mass of a polystyrene-based resin as resin components, wherein the polyethylene-based resin has a density of 0.900-0.916 g/cm, a melt flow rate of 1.0-5.0 g/10 min measured under a load of 2.16 kg at 190°C, and a vicat softening temperature of 88-95°C.

Description

  The present invention relates to composite resin particles, expandable composite resin particles, pre-expanded particles, and a foam molded article. More specifically, the present invention relates to a composite resin particle having a high magnification and capable of obtaining a foamed molded article having excellent impact resistance, and relates to a foamable composite resin particle obtained from the composite resin particle and a pre-expanded particle. It also relates to foamed molded products.

  Conventionally, foamed molded articles containing a polystyrene resin as a resin component have excellent physical properties such as moldability, heat insulation, impact resistance and buffering properties, so that they are cushioning materials for packaging and structural members in the automotive field. Widely used as building materials.

  Moreover, when using a foaming molding in such a use, high impact resistance is calculated | required by a foaming molding. In view of the above points, Patent Document 1 discloses a foamed molded article including a polystyrene resin and a polyethylene resin as resin components as a foamed molded article having excellent impact resistance.

International Publication No. 2006/027944

  At present, from the viewpoint of reducing the weight and cost of foamed molded products, it has become desirable to increase the magnification and lower the specific gravity of the foamed molded products in addition to impact resistance. However, when the foamed molded product is made higher, the impact resistance of the foamed molded product decreases in inverse proportion to the increase in the multiple, and depending on the application, desired physical properties such as impact resistance may not be obtained. .

  In particular, when foamed molded products are used as cushioning materials for home appliances, the size of home appliances is increasing, and the foamed molded products are easily damaged, broken, and defective in appearance due to vibrations during transportation and impacts caused by accidents. It has become. Moreover, the damage of the household appliance accompanying it is also easy to occur. Therefore, in preparation for these, the foamed molded body is required to have both higher magnification and impact resistance at a higher level than the above-mentioned applications.

  In addition, a reusable foamed molded body has been demanded from the growing awareness of environmental issues. However, when a foamed molded product is used a plurality of times, depending on the intended use, the foamed molded product cannot resist an impact or the like, and may cause a change in multiples or a decrease in impact resistance. For this reason, from this point of view, the foamed molded body is required to have both higher magnification and impact resistance at a higher level.

However, with respect to the above-mentioned problems, the foam molded article described in Patent Document 1 and the conventional foam molded article are recognized to have a certain improvement in impact resistance, but are not always satisfactory from such a viewpoint. It wasn't going.
Therefore, in view of these problems, it is an object to provide a foamed molded article having a high multiple and excellent impact resistance. Another object of the present invention is to provide composite resin particles from which the foamed molded product can be obtained.

Thus, according to the present invention, the resin component includes 100 parts by mass of a polyethylene resin and 200 to 900 parts by mass of a polystyrene resin,
The polyethylene-based resin has a density of 0.900 to 0.916 g / cm ³ , a melt flow rate of 1.0 to 5.0 g / 10 min measured under a load of 190 ° C. and 2.16 kg, and 88 to 95. Composite resin particles characterized by having a Vicat softening temperature of 0C are provided.

  Moreover, according to this invention, the expandable composite resin particle which can be obtained from the said composite resin particle is also provided.

  The present invention also provides pre-expanded particles that can be obtained from the composite resin particles.

  Moreover, according to this invention, the foaming molding which can be obtained from the said composite resin particle is also provided.

Since the composite resin particle of the present invention contains, as a resin component, a polyethylene resin excellent in rigidity (impact resistance) and a polystyrene resin excellent in foamability at a predetermined ratio, it is obtained from the composite resin particle of the present invention. The foamed molded product can have a desired high multiple and excellent impact resistance. In addition, the polyethylene resin of the present invention has a melt flow rate of 1.0 to 5.0 g / 10 min measured at a density of 0.900 to 0.916 g / cm ³ and a load of 190 ° C. and 2.16 kg. , Having a Vicat softening temperature of 88-95 ° C. For this reason, when the expandable composite resin particles obtained from the composite resin particles of the present invention are heated, first, foaming derived from the polyethylene resin portion is recognized. Further, when heating is continued, foaming derived from the styrene resin portion is then recognized, and as a result, two foaming peaks can be confirmed. Therefore, higher foaming can be achieved than in the case where the foaming temperature zones of the polyethylene resin and the polystyrene resin are conventionally combined. Furthermore, the fusion property between the pre-expanded particles is improved, and as a result, the impact resistance of the foamed molded product can be further improved at a low pressure.
Therefore, according to the present invention, it is possible to provide composite resin particles that can obtain a foamed molded article having a high multiple and excellent impact resistance.

  Further, according to the present invention, when the composite resin particles contain carbon black, the composite resin particles contain carbon black as a colorant, so that a foamed molded article having a high multiple and excellent in impact resistance and appearance is obtained. The composite resin particle which can be provided can be provided.

  Further, according to the present invention, when composite resin particles are obtained by seed polymerizing a styrene monomer to the polyethylene resin, desired composite resin particles can be obtained more easily. It is possible to provide composite resin particles that can obtain a foamed molded article having a high multiple and further excellent impact resistance.

  ADVANTAGE OF THE INVENTION According to this invention, the foamable composite resin particle which can obtain the foaming molding which has a high multiple and was excellent also in impact resistance can be provided.

  According to the present invention, when the foamable composite resin particles show two foaming peaks when the foamable composite resin particles are allowed to stand at 90 to 100 ° C. for 300 seconds, they have a high multiple in a wider temperature range. And the foamable composite resin particle which can obtain the foaming molding excellent also in impact resistance can be provided.

  ADVANTAGE OF THE INVENTION According to this invention, the pre-expanded particle which can obtain the foaming molding which has a high multiple and was excellent also in impact resistance can be provided.

  Moreover, according to this invention, the pre-expanded particle which can obtain the foaming molding which has a high bulk multiple of 55 times or more and was excellent also in impact resistance can be provided.

  According to the present invention, a foamed molded article having a high multiple and excellent impact resistance can be obtained.

  According to the present invention, it is possible to provide a foamed molded article having a high multiple such as 55 times or more and excellent in impact resistance.

FIG. 1 is a graph showing the foaming peaks of Examples and Comparative Examples.

The characteristics of the present invention include, as a resin component, 100 parts by mass of a polyethylene resin and 200 to 900 parts by mass of a polystyrene resin,
The polyethylene-based resin has a density of 0.900 to 0.916 g / cm ³ , a melt flow rate of 1.0 to 5.0 g / 10 min measured under a load of 190 ° C. and 2.16 kg, and 88 to 95. Composite resin particles having a Vicat softening temperature of ° C.

  Specifically, the composite resin particle of the present invention has, as a resin component, 200 to 900 parts by mass of a polystyrene resin having excellent foamability with respect to 100 parts by mass of polyethylene resin having excellent rigidity (impact resistance). Include in percentage. For this reason, the foaming molding obtained from the composite resin particle of this invention can have a desired high multiple and the outstanding impact resistance. In particular, as described below, when the composite resin particles are obtained by seed polymerizing a styrene monomer to seed particles containing a polyethylene resin, the particle surface layer portion has a high polyethylene resin ratio, and the particle center portion is In some cases, composite resin particles having a resin composition having a high polystyrene-based resin ratio can be obtained. In this case, according to the present invention, it may be possible to obtain composite resin particles that can obtain a foamed molded article having a high multiple and further excellent impact resistance.

The polyethylene-based resin used has a density of 0.900 to 0.916 g / cm ³ and a melt flow rate of 1.0 to 5.0 g / 10 minutes measured at 190 ° C. under a load of 2.16 kg and It has a Vicat softening temperature of 88-95 ° C. For this reason, when the polyethylene resin of the present invention is heated from a low temperature, the softening can be started from a lower temperature as compared with a normal polyethylene resin, and further the fluidity of a resin component useful for foaming is ensured. be able to. For this reason, when the expandable composite resin particles obtained from the composite resin particles of the present invention are heated, first, foaming derived from the polyethylene-based resin portion starting to soften at a lower temperature is recognized. Further, when the heating is continued, the foaming of the polyethylene resin part is maintained, that is, the foamable composite resin particles are not shrunk, and then the foaming derived from the styrene resin part is recognized. A peak can be confirmed. Therefore, even higher foaming can be achieved than in the case where the foaming temperature zones of the polyethylene resin and the polystyrene resin have been matched so far. In addition, pre-expanded particles having a desired bulk factor can be produced easily and stably.

  Furthermore, the fusion property between the pre-expanded particles can be improved even by molding at a low pressure, and as a result, the impact resistance of the foamed molded product can be further improved. For this reason, according to this invention, the composite resin particle which can obtain the foaming molding which has a high multiple and was excellent also in impact resistance can also be provided.

Accordingly, a foamed molded product having a high multiple has not been found in spite of its excellent impact resistance, but according to the present invention, it has a high multiple and is excellent in impact resistance. A foamed molded product can be provided. Moreover, the composite resin particle which can obtain the said foaming molding can be provided.
Hereinafter, the composite resin particles, expandable composite resin particles, pre-expanded particles and foamed molded product of the present invention will be described in detail.

The foamed molded article of the present invention is
(1) an impregnation step of obtaining expandable composite resin particles by impregnating the composite resin particles with a foaming agent;
(2) a pre-foaming step of obtaining pre-foamed particles by pre-foaming the foamable composite resin particles;
(3) It can be obtained by a production method including a foam molding step of obtaining a foam molded article by foam molding of pre-expanded particles.

(Composite resin particles)
In the present invention, the composite resin particle means a resin particle containing a plurality of resin components. Specifically, the composite resin particle means a resin particle containing at least a polyethylene resin and a polystyrene resin as resin components.

  The mass ratio between raw materials used, such as raw material monomer, raw material resin, and other components, and the mass of composite resin particles, expandable composite resin particles, pre-expanded particles, resin components in foamed molded products, other components, etc. The ratio is substantially the same.

  In the present invention, the polyethylene resin means an ethylene homopolymer or a copolymer of an ethylene monomer as a main component and another monomer copolymerizable with the ethylene monomer. Moreover, having ethylene monomer as a main component means that ethylene monomer occupies 50 mass parts or more in 100 mass parts of all monomer components. Furthermore, an ethylene homopolymer means that an ethylene monomer occupies 93 mass parts or more in 100 mass parts of all the monomer components.

  Specifically, as the polyethylene resin, for example, ethylene homopolymer, ethylene-acrylic acid copolymer, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, and ethylene-methyl methacrylate copolymer Such polymers can be mentioned. Since desired physical properties can be obtained more easily, an ethylene homopolymer is preferred as the polyethylene resin.

  Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 3,3-dimethyl-1-butene, 4-methyl-1-pentene, 4,4-dimethyl-1-pentene, 1 Mention may be made of vinyl monomers such as -heptene and 1-octene. Furthermore, since it is possible to obtain expandable composite resin particles and pre-expanded particles that can be expanded in a wider temperature range, 1-butene and 1-hexene are preferable as the α-olefin.

  On the other hand, as long as the desired physical properties are not affected, the polyethylene resin may be used alone or in combination of two or more. Moreover, when using a copolymer as a polyethylene-type resin, a copolymer may be a random copolymer and a block copolymer may be sufficient as it.

In addition, since the crystallinity of the polyethylene resin can be adjusted to a range suitable for heating and foaming, the polyethylene resin of the present invention is 0.900 to 0.916 g / cm ³ , preferably 0.905 to 0.00. It has a density of 915 g / cm ³ , more preferably 0.909 to 0.915 g / cm ³ . When the density of the polyethylene resin is higher than 0.916 g / cm ³ , the crystallinity of the polyethylene resin becomes high, and the foamable composite resin particles may not be foamed in a wide temperature range. On the other hand, when the density of the polyethylene resin is less than 0.900 g / cm ³ , the crystallinity of the polyethylene resin is lowered, and there is too much difference between the foaming temperature zones of the polyethylene resin and the polystyrene resin, so that the desired multiple is obtained. It may not be possible to obtain a foamed molded product.

  Similarly, since the adjustment as described above can be easily performed, the polyethylene-based resin of the present invention has a load of 190 ° C. and 2.16 kg, 1.0 to 5.0 g / 10 min, preferably 1. It has a melt flow rate of 0 to 4.0 g / 10 min, more preferably 1.0 to 3.0 g / 10 min. When the melt flow rate of the polyethylene-based resin is higher than 5.0 g / 10 min, it may be impossible to obtain a foamed product having a desired multiple. On the other hand, when the melt flow rate of the polyethylene resin is less than 1.0 g / 10 minutes, the crystallinity of the polyethylene resin is increased, and in this case as well, it may not be possible to obtain a desired multiple foamed product.

  Similarly, the polyethylene resin of the present invention has a Vicat softening temperature of 88 to 95 ° C, preferably 90 to 95 ° C, more preferably 90 to 94 ° C. By measuring the Vicat softening temperature of the polyethylene resin, it is possible to more easily grasp the softening start temperature of the resin component. Similarly, when the Vicat softening temperature of the polyethylene resin is higher than 95 ° C., it may be impossible to obtain a foamed product having a desired multiple. On the other hand, when the Vicat softening temperature of the polyethylene resin is lower than 88 ° C., the crystallinity of the polyethylene resin is increased, and in this case as well, it may not be possible to obtain a desired multiple foamed product.

  Furthermore, from the same viewpoint, the polyethylene-based resin of the present invention can preferably have a melting point temperature of 110 to 125 ° C, more preferably 110 to 120 ° C.

Furthermore, similarly, the polyethylene resin of the present invention preferably has a number average molecular weight (Mn) of 60 × 10 ³ to 80 × 10 ³ , more preferably 70 × 10 ³ to 80 × 10 ³ , It has a weight average molecular weight (Mw) of 160 × 10 ³ to 200 × 10 ³ , more preferably 170 × 10 ^{3 to} 190 × 10 ³ . The number average molecular weight and the weight average molecular weight can be measured by GPC (gel permeation chromatograph).

On the other hand, the impact resistance of the foamed molded article can be further improved by reducing the amount of the short chain length component of the polyethylene-based resin that hardly contributes to the impact resistance. For this reason, the polyethylene-based resin of the present invention has the following formula (I) for Mw / Mn, which is a general index for molecular weight distribution:
1.5 ≦ Mw / Mn ≦ 3.5 (I)
It is preferable to satisfy the following formula (II):
2.0 ≦ Mw / Mn ≦ 3.0 (II)
It is more preferable to satisfy.

  Moreover, a polyethylene-type resin can be manufactured using well-known polymerization methods, such as a gas phase polymerization method. Furthermore, since a polyethylene resin having the above properties can be produced more easily, a polymerization method of an ethylene monomer using a metallocene compound as a catalyst is preferable.

  Examples of the metallocene compound include known metallocene compounds used for polymerization of ethylene monomers. For example, a metallocene compound containing a tetravalent transition metal element can be preferably used. Specifically, cyclopentadienyl titanium tris (dimethylamide), methylcyclopentadienyl titanium tris (dimethylamide), bis (cyclopentadienyl) titanium dichloride, dimethylsilyltetramethylcyclopentadienyl-t-butyl Amidozirconium dichloride, dimethylsilyltetramethylcyclopentadienyl-t-butylamidohafnium dichloride, dimethylsilyltetramethylcyclopentadienyl-pn-butylphenylamidozirconium chloride, methylphenylsilyltetramethylcyclopentadienyl-t -Butyramide hafnium dichloride, indenyl titanium tris (dimethylamide), indenyl titanium tris (diethylamide), indenyl titanium tris (di n- propyl amide), it can be exemplified metallocene compounds such as indenyl titanium bis (di -n- butylamido) and indenyl titanium bis (di -n- propyl amide). These metallocene compounds may be used alone or in combination of two or more kinds, and may be used in combination with, for example, a cocatalyst such as methylaluminoxane or a boron-based compound.

  In the present invention, the polystyrene resin means a styrene homopolymer or a copolymer of a styrene monomer as a main component and another monomer copolymerizable with the styrene monomer. The styrene monomer means a styrene monomer or a mixture of a styrene monomer as a main component and another monomer copolymerizable with the styrene monomer. Here, the styrene monomer as a main component means that the styrene monomer occupies 90 parts by mass or more with respect to 100 parts by mass of all monomers.

  As other monomers, vinyl such as α-methylstyrene, p-methylstyrene, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, alkyl acrylate ester, alkyl methacrylate ester, divinylbenzene and polyethylene glycol dimethacrylate Mention may be made of system monomers. In the present invention, alkyl means alkyl having 1 to 30 carbon atoms. A styrene homopolymer capable of stably pre-foaming the expandable composite resin particles is preferable.

  In addition, since the excellent rigidity (impact resistance) of the polyethylene resin and the excellent foamability of the polystyrene resin can be introduced into the foamed molded article, the polystyrene resin is based on 100 parts by mass of the polyethylene resin. 200-900 mass parts, Preferably it is 200-600 mass parts, More preferably, 200-500 mass parts is used. When the polystyrene resin is less than 200 parts by mass, it may be impossible to obtain a foamed molded article having a sufficient multiple. On the other hand, when the amount of polystyrene resin is more than 900 parts by mass, a foamed molded article having sufficient impact resistance may not be obtained.

  In addition, as a combination of the polyethylene resin and the polystyrene resin contained in the foam molded article of the present invention, a foam molded article having more excellent impact resistance can be obtained. Therefore, an ethylene homopolymer and a styrene homopolymer The combination with is preferred.

  Furthermore, since a beautiful foam molded article can be obtained, the composite resin particles of the present invention can also contain a colorant. Any known colorant such as organic dyes, organic pigments, and inorganic pigments can be used as the colorant as long as the desired physical properties are not affected.

Examples of organic dyes include azo dyes, anthraquinone dyes, phthalocyanine dyes, indigoid dyes, quinone imine dyes, carbonium dyes, nitro dyes, and nitroso dyes.
Examples of the organic pigments include azo-based, phthalocyanine-based, selenium-based, quinacrine-based, dioxazine-based and isoindoline-based pigments.
Examples of inorganic pigments include carbon black, iron oxide, titanium oxide, chromium oxide, and ultramarine.

  In addition, since a more beautiful foamed molded article can be obtained, it is preferable to use carbon black as a colorant. Examples of carbon black include furnace black, channel black, thermal black, acetylene black, graphite, and carbon fiber. Since carbon black can obtain an even more beautiful foam-molded article, it is preferably contained in an amount of 0.5 to 3 parts by mass, more preferably 1 to 2 parts by mass with respect to 100 parts by mass of the composite resin particles.

  As long as the polyethylene resin and polystyrene resin of the present invention do not affect the desired physical properties, a vinyl group, a carbonyl group, an aromatic group, an ester group, an ether group, an aldehyde group, an amino group, a nitrile group, and a nitro group, respectively. Such a functional group may be contained, and may be cross-linked by a cross-linking agent having two or more vinyl groups, and may be used alone or in combination of two or more.

  Similarly, other resin components may be included. Examples of other resin components include known thermoplastic resins, thermosetting resins, and the like. Specifically, poly (meth) acrylic resins, polyphenylene ether resins, polycarbonate resins, and polyester resins including polylactic acid. Etc. In addition, (meth) acryl means acryl or methacryl.

  Furthermore, the composite resin particles may contain other additives as long as a desired foamed molded product can be obtained. Specific examples include flame retardants, flame retardant aids, colorants, light stabilizers, UV absorbers, pigments, dyes, antifoaming agents, thickeners, heat stabilizers, nucleating agents, lubricants and antistatic agents. Can be mentioned.

  On the other hand, the composite resin particles are preferably spherical to substantially spherical (egg-shaped) from the viewpoint of ensuring fluidity, and preferably 0.8 to 2.0 mm, more preferably 1.0 to 2.0 mm on average. It has a particle size.

(Production method of composite resin particles)
The production method of the composite resin particles is not particularly limited, and any known method can be used. For example, a seed polymerization method can be used. Moreover, since a desired composite resin particle can be obtained more easily, a seed polymerization method is preferable. When the seed polymerization method is used, the composite resin particles are preferably obtained by adding and polymerizing a styrene monomer in an aqueous medium in which seed particles made of polyethylene resin are dispersed and held.

  The seed particles can be obtained by a known method. For example, polyethylene resin particles can be produced by first melt-extruding a polyethylene resin using an extruder and then granulating it by underwater cutting, strand cutting, or the like. Usually, the shape of the polyethylene-based resin to be used is, for example, a spherical shape, an elliptical spherical shape (egg shape), a cylindrical shape, a prismatic shape, a pellet shape, or a granular shape. In the present invention, seed particles made of polyethylene resin are also referred to as micropellets. Further, if necessary, an air conditioner such as talc can be added to the micropellet.

  Further, composite resin particles can be obtained by dispersing the micropellets in an aqueous medium in a polymerization vessel and polymerizing the micropellets while impregnating the micropellets. Examples of the aqueous medium include water, a mixed medium of water and a water-soluble solvent (for example, alcohol), and water is preferable from the environmental viewpoint.

  The impregnation of the styrene monomer into the polyethylene resin may be performed while polymerizing the styrene monomer, or may be performed before the polymerization is started. Since the process time can be further shortened, it is preferable to perform the impregnation while polymerizing. In this case, it is preferable to add the styrenic monomer continuously or intermittently to the aqueous medium in the polymerization vessel.

An oil-soluble radical polymerization initiator can be used for the polymerization of the styrene monomer. As the radical polymerization initiator, a polymerization initiator widely used for the polymerization of styrene monomers can be used. For example, benzoyl peroxide, lauroyl peroxide, t-butyl peroxy octoate, t-hexyl peroxy octoate, t-butyl peroxy benzoate, t-amyl peroxy benzoate, t-butyl peroxybivalate, t- Butyl peroxyisopropyl carbonate, t-hexyl peroxyisopropyl carbonate, t-butylperoxy-3,3,5-trimethylcyclohexanoate, di-t-butylperoxyhexahydroterephthalate, 2,2-di- organic peroxides such as t-butylperoxybutane, di-t-hexyl peroxide and dicumyl peroxide;
Mention may be made of azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile. A water-soluble radical polymerization initiator such as ammonium persulfate (APS) and potassium persulfate (KPS) can also be used in combination. The polymerization initiator is usually preferably added at a ratio of 0.02 to 2.0 parts by mass with respect to 100 parts by mass of the styrene monomer.

It is also preferable to add a dispersant to the aqueous medium. Examples of such a dispersant include organic dispersants such as partially saponified polyvinyl alcohol, polyacrylate, polyvinyl pyrrolidone, carboxymethyl cellulose, and methyl cellulose;
Mention may be made of inorganic dispersants such as magnesium pyrophosphate, calcium pyrophosphate, calcium phosphate, calcium carbonate, magnesium phosphate, magnesium carbonate and magnesium oxide.

In addition, anionic surfactants such as sodium oleate, sodium lauryl sulfate, sodium dodecylbenzene sulfonate, alkyl naphthalene sulfonate and alkyl phosphate ester salts as required;
Nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine and glycerin fatty acid ester;
Amphoteric surfactants such as lauryldimethylamine oxide; as well as cationic surfactants such as aliphatic quaternary ammonium salts may be used.

  The shape and structure of the polymerization vessel are not particularly limited as long as they are conventionally used for suspension polymerization and seed polymerization. Further, the shape of the stirring blade is not particularly limited, and specifically, a paddle blade such as a V-shaped paddle blade, a fiddler blade, an inclined paddle blade, a flat paddle blade, a pull margin blade, a turbine blade, a fan turbine blade, etc. Mention may be made of propeller blades such as turbine blades and marine propeller blades. Of these stirring blades, paddle blades are preferred. The stirring blade may be a single-stage blade or a multi-stage blade. A baffle may be provided in the polymerization container.

  Further, the temperature of the aqueous medium when the styrenic monomer is impregnated and polymerized in the micropellets is not particularly limited, but is preferably 110 to 140 ° C., more preferably because polymerization can be performed more stably. Is 110-130 ° C. Moreover, as long as the composite resin particle which has a desired physical property can be obtained, superposition | polymerization may be performed under reduced pressure and may be performed on pressurization conditions. Furthermore, the manufacturing process time is appropriately set according to manufacturing equipment and manufacturing conditions.

  After the polymerization, in order to obtain expandable composite resin particles, the suspension containing the composite resin particles may be used as it is, or the composite resin particles recovered from the suspension may be used.

  Also, composite resin particles can be produced by melt-kneading a polyethylene resin and a polystyrene resin.

(Expandable composite resin particles)
In the present invention, the expandable composite resin particles mean heat-expandable composite resin particles containing a plurality of resin components, which can be obtained by impregnating the composite resin particles with a foaming agent. Specifically, the foamable composite resin particle means a heat-foamable resin particle containing at least a polyethylene resin and a styrene resin as resin components and further containing a foaming agent.

  Moreover, the conventionally used foaming agent can be used as the foaming agent. Examples include blowing agents such as saturated aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane and hexane, and inert gases such as carbon dioxide and nitrogen.

  Further, from the viewpoint of imparting high foamability to the foamable composite resin particles, saturated aliphatic hydrocarbons are preferable, and any of normal butane, isobutane, normal pentane, and isopentane is more preferable. A foaming agent may be used alone or two or more kinds may be used in combination as long as the foam molding process and desired physical properties are not affected.

  Moreover, since uniform impregnation property, foamability, and moldability can be expected, a foaming agent may be used together with a foaming aid. Specifically, plasticizers such as toluene, xylene, cyclohexane, ethyl acetate, diisobutyl adipate, diacetylated monolaurate and coconut oil may be added as foaming aids.

  On the other hand, when the expandable composite resin particles of the present invention are allowed to stand at 90 to 100 ° C. for 300 seconds, the expandable composite resin particles can also exhibit two expansion peaks. In this case, as compared with the case where the expandable composite resin particles have one expansion peak, the high bulk multiple can be maintained for a long time. In the present invention, the foaming peak means the maximum value of the bulk multiple of the pre-foamed particles confirmed when the foamable composite resin particles are heated and foamed.

  Furthermore, since the foamable composite resin particles can be foamed to a desired high bulk multiple, the foaming agent is preferably 7 to 13 parts by mass, more preferably 8 to 8 parts per 100 parts by mass of the foamable composite resin particles. 11 parts by mass are included.

  On the other hand, the foamable composite resin particles are also preferably spherical to substantially spherical (egg-like) from the viewpoint of ensuring fluidity. Similarly, the expandable composite resin particles of the present invention preferably have an average particle diameter of 0.8 to 2.0 mm, more preferably 1.0 to 2.0 mm.

(Method for producing expandable composite resin particles)
The production method of the expandable composite resin particles of the present invention is not particularly limited, and any known impregnation method can be used. Specifically, the impregnation with the foaming agent can be performed in the presence of the foaming agent, in the presence or absence of an aqueous medium. The impregnation of the present invention corresponds to impregnating the composite resin particles with the foaming agent by contacting and immersing the composite resin particles in an excessive amount of the foaming agent.

More specifically,
A method in which a foaming agent and composite resin particles are mixed in a rotary mixer;
Examples thereof include a method of injecting a foaming agent into an aqueous medium in which composite resin particles are dispersed and impregnating the composite resin particles with the foaming agent. Moreover, as a production facility, a known impregnation step facility can be used.

  Further, since the temperature of the production process can be easily controlled, the impregnation of the present invention is preferably performed at a temperature of 50 to 75 ° C, more preferably 60 to 70 ° C.

  Furthermore, since the volatilization of the blowing agent can be more easily suppressed, the impregnation of the present invention is preferably performed under a pressure of 0.06 to 0.09 MPa, more preferably 0.07 to 0.09 MPa. In addition, the said pressure means the pressure of the gauge with which the manufacturing equipment which impregnates was equipped. On the other hand, the manufacturing process time is appropriately set according to manufacturing equipment and manufacturing conditions. On the other hand, isolation of expandable composite resin particles from an aqueous medium, a foaming agent, and the like can be performed using a known method.

(Pre-expanded particles)
In the present invention, the pre-expanded particles mean resin particles obtained by heating and foaming expandable composite resin particles containing at least a polyethylene resin and a polystyrene resin as resin components to a predetermined bulk expansion ratio.

  The pre-expanded particles of the present invention can be produced using a known foaming method. As an example, pre-expanded particles can be obtained by introducing expandable composite resin particles into a known pre-expander and heating to a predetermined bulk factor. Steam is preferably used as the heating medium for heating.

  The polyethylene resin of the present invention has a Vicat softening temperature of 88 to 95 ° C. For this reason, compared with the expandable composite resin particle containing the conventional polyethylene-type resin and polystyrene-type resin, a resin component starts softening from lower temperature. As a result, the foamable composite resin particles can start foaming from a lower temperature.

  More specifically, the foaming composite resin particles are heated and foamed in a wide temperature range from low temperature to high temperature because the polyethylene resin softens and starts foaming, and then the polystyrene resin softens and starts foaming. Can do. Therefore, according to the present invention, the pre-expanded particles can be sufficiently fused from a low temperature. Furthermore, according to the present invention, since pre-foaming can be performed in a wide foaming temperature range, temperature management during the manufacturing process can be simplified.

  On the other hand, if necessary, an antistatic agent such as polyoxyethylene alkylphenol ether and stearic acid monoglyceride may be added to the foamable composite resin particles during preliminary foaming. The pressure in the pre-foaming machine and the manufacturing process time when performing pre-foaming can be set as appropriate according to the expandable composite resin particles.

  The expandable composite resin particle of the present invention contains a polystyrene-based resin having an excellent foamability as a resin component at a suitable ratio. The expandable composite resin particles of the present invention also contain the above-described polyethylene resin in a suitable ratio.

  For this reason, the pre-expanded particles of the present invention can have a high bulk multiple. Specifically, the pre-expanded particles of the present invention can have a bulk factor of preferably 55 times or more, more preferably 55 to 80 times. This indicates that the pre-expanded particles of the present invention have a high bulk factor.

  On the other hand, the pre-expanded particles are also preferably spherical to substantially spherical (egg-like) from the viewpoint of ensuring fluidity, and preferably 2.4 to 7.0 mm, more preferably 3.0 to 7.0 mm on average. It has a particle size.

(Foamed molded product)
In the present invention, the foam molded article means a resin molded article obtained by foam-molding pre-expanded particles containing at least a polyethylene resin and a polystyrene resin as resin components into a predetermined shape.

  The foamed molded product of the present invention can be produced using a known foam molding method. As an example of the foam molding method, pre-foamed particles are filled in a mold of a known foam molding machine, and the pre-foamed particles are heated again by heating on the one hand, reverse one-side heating, and both sides heating, and then pre-foaming is performed. A foam-molded article can be obtained by thermally fusing the particles together. As the heating medium for heating, water vapor having a vapor pressure of 0.05 to 0.09 MPa and a vapor temperature of 110 to 118 ° C. is preferably used. From the viewpoint of energy saving, it is preferable to foam-mold the pre-expanded particles at a steam pressure of 0.05 to 0.07 MPa and a steam temperature of 110 to 116 ° C.

  The polyethylene resin of the present invention has a Vicat softening temperature of 88 to 95 ° C. For this reason, the pre-expanded particles of the present invention are softened from a lower temperature than the conventional pre-expanded particles containing a polyethylene resin and a polystyrene resin at the time of foam molding as in the case of the pre-expansion. You can start again. Therefore, according to the present invention, the pre-expanded particles can be uniformly fused at a low temperature.

  Further, according to the present invention, since foam molding can be performed in a wide range of foaming temperatures, temperature management during the manufacturing process can be facilitated. In addition, the pressure in the foam molding machine and the manufacturing process time when performing foam molding can be appropriately set according to the pre-expanded particles.

The pre-expanded particles of the present invention also contain a polystyrene resin having an excellent foamability as a resin component at a suitable ratio. Similarly, the polyethylene resin of the present invention has a melt flow of 1.0 to 5.0 g / 10 min measured at a density of 0.900 to 0.916 g / cm ³ and a load of 190 ° C. and 2.16 kg. Since it has a rate, the crystallinity of the polyethylene resin can be adjusted to a suitable range by heating and foaming, and the foamability of the polyethylene resin can be improved.

  For this reason, the foamed molded product of the present invention can preferably have a multiple of 55 times or more, more preferably 55 to 80 times. This has shown that the foaming molding of this invention has a high multiple.

  On the other hand, the foamed molded product of the present invention can be obtained by sufficiently and stably fusing pre-expanded particles in a low temperature region as described above. The foamed molded article of the present invention also contains a polyethylene resin having excellent rigidity as a resin component. For this reason, when the multiple of a foaming molding is 60 times, it can have a falling ball impact value of preferably 30 cm or more, more preferably 35 cm or more. Moreover, when the multiple of a foaming molding is 50 times, it can have a falling ball impact value of preferably 40 cm or more, more preferably 45 cm or more.

  This has shown that the foaming molding of this invention has a high multiple. In addition, the foamed molded article of the present invention has a good falling ball impact value, that is, excellent impact resistance, despite having a high multiple that could not be obtained conventionally. It also shows.

  In addition, the foamed molded article of the present invention can preferably have a fusion rate of 80 to 100%, more preferably 90 to 100%. This indicates that the foamed molded product of the present invention is excellent in impact resistance because the pre-foamed particles are firmly fused to each other.

  Therefore, the foamed molded product of the present invention is a foamed molded product having a high multiple and excellent impact resistance. For this reason, the foaming molding of this invention can be used widely as a structural member, a building member, etc. in the motor vehicle field | area, and can also be especially used as a shock absorbing material for household appliances.

  Hereinafter, although an example is given and explained further, the present invention is not limited by these examples. Various measurement methods and production conditions described in the examples will be described below.

<Density of resin component>
The density of the resin component is measured according to JIS K6992-1,2.

<Melt flow rate (MFR) of resin component>
MFR is measured under a load of 2.16 kg at 190 ° C. in accordance with JIS K7210: 1999. The measurement apparatus and measurement conditions are described below.

Measuring apparatus: Melt indexer manufactured by Toyo Seiki Seisakusho Measuring temperature: 190 ° C
Measurement load: 2.16kg
Orifice diameter: 2.09 mm
5 g of a polyethylene resin is placed in a melt indexer preheated to 190 ° C. and left for 4 minutes. Next, a 2.16 kg weight is placed on the piston, and a polyethylene resin is extruded from an orifice diameter of 2.09 mm and measured.

<Number average molecular weight (Mn) and weight average molecular weight (Mw) of resin component>
The GPC apparatus used for the measurement was HLC-8121GPC / HT manufactured by Tosoh Corporation, TSKgel GMHhr-H (20) HT manufactured by Tosoh Corporation was used as the column, the column temperature was set to 140 ° C., and 1,2 as the eluent. , 4-trichlorobenzene is used. The measurement sample is adjusted to a concentration of 1.0 mg / mL, and the amount injected into the GPC device is 0.3 mL. The calibration curve for each molecular weight is calibrated using a polyethylene sample with a known molecular weight. Mn and Mw are determined as linear polyethylene equivalent values.

<Vicat softening temperature of resin component>
It is measured by the method described in JIS K7206 “Method for testing softening temperature by thermomechanical analysis of thermoplastic film and sheet”. That is, after the resin particles are hot-pressed and crushed to a thickness of 2 mm, a flat rectangular film-shaped test piece having a length of 10 mm × width of 20 mm × thickness of 2 mm is produced, and a heat / stress / strain measuring device (manufactured by Seiko Instruments Inc.) , Product name “TMA / SS6200”), needle-in test mode (needle tip area 1 mm ² ), load 50 g, the needle is applied to the film specimen and the temperature is raised at a rate of 5 ° C./min. Then, the temperature at which the distortion of the film-like test piece occurs is defined as the Vicat softening temperature of the resin particles.

<Melting temperature of resin component>
The density of the resin component is measured according to JIS K7121.

<Average particle diameter of composite resin particles, expandable composite resin particles and pre-expanded particles>
The average particle size of the sample is calculated by taking the average particle size of these particles. That is, the average particle diameter of the present invention means a volume average particle diameter. In addition, the average particle diameter of a sample can be measured using the measuring apparatus marketed as the product name "Coulter Multisizer II" from Beckman Coulter, Inc., for example.

<Foaming evaluation of foamable composite resin particles>
The weight (a) of about 2 g of expandable composite resin particles is weighed in the second decimal place. The weighed expandable composite resin particles are put in a container, and it is confirmed that the temperature in the foaming tank is 80 ° C. or less. Steam is heated and foamed at 90 to 100 ° C. by introducing (vapor temperature: 99 ° C.). At this time, the heating time was changed to 1, 2, 3, and 4 minutes, and the expansion ratio immediately after taking out from the foaming tank was measured. The heating time is from the time when the temperature in the foaming tank becomes 90 ° C. or higher. The expansion ratio is obtained by putting about 2 g (a) of pre-expanded particles into a measuring cylinder and measuring the volume, and dividing the volume by (a) to obtain the bulk multiple of the pre-expanded particles. FIG. 1 is a graph showing foaming peaks when the foamable composite resin particles of Examples and Comparative Examples are left at 90 to 100 ° C. for 300 seconds.

<Foaming agent content of expandable composite resin particles>
5 to 20 mg of the foamable composite resin particles are accurately weighed and used as a measurement sample. This measurement sample is set in a pyrolysis furnace (manufactured by Shimadzu Corporation: PYR-1A) maintained at 180 to 200 ° C., and the measurement sample is sealed and heated for 120 seconds to release the foaming agent component. A chart of the blowing agent component is obtained under the following conditions using a gas chromatograph (manufactured by Shimadzu Corporation: GC-14B, detector: FID) for the released blowing agent component. Based on the calibration curve of the foaming agent component measured in advance, the foaming agent content (parts by mass) in the foamable composite resin particles is calculated from the obtained chart.

Gas chromatograph measurement conditions Column: “Shimalite 60/80 NAW” (φ3 mm × 3 m) manufactured by Shinwa Kako Co., Ltd. Column temperature: 70 ° C.
Detector temperature: 110 ° C
Inlet temperature: 110 ° C
Carrier gas: Nitrogen carrier gas Flow rate: 60 mL / min

<Bulk multiple of pre-expanded particles>
The weight (a) of about 5 g of pre-expanded particles is weighed at the second decimal place. Next, weighed pre-expanded particles in a 500 cm ³ graduated cylinder with a minimum memory unit of 5 cm ³ , and a round resin plate slightly smaller than the caliber of the graduated cylinder, about 1.5 cm wide at the center, The volume (b) of the pre-expanded particles is read by applying a pressing tool in which a rod-shaped resin plate having a length of about 30 cm is fixed upright, and the bulk density (g) of the pre-expanded particles is calculated by the formula (a) / (b). / Cm ³ ). The bulk multiple is the reciprocal of the bulk density, that is, the formula (b) / (a).

In the present invention,
(1) If the bulk multiple is 55 times or more: Pass (○)
(2) If the bulk multiple is less than 55 times: rejected (x)
Is determined.

<Multiple of foam molding>
The weight (c) and volume (d) of a test piece (example 75 × 300 × 35 mm) cut out from a foamed molded product (after being molded and dried at 40 ° C. for 20 hours or more) each have three or more significant figures. And the density (g / cm ³ ) of the foamed molded product is obtained from the formula (c) / (d). The multiple is the reciprocal of the density, that is, the formula (d) / (c).

In the present invention,
(1) When the multiple is 55 times or more: Pass (○)
(2) If the multiple is less than 55 times: Fail (×)
Is determined.

<Falling ball impact value of foam molding>
In measuring the impact strength, a sample is prepared by cutting a foamed molded product into a size of 215 × 40 × 20 mm. Next, after placing this sample on a pair of holding members arranged with a span of 155 mm, the sample has a weight of 321 g from a predetermined height at an intermediate position between both holding members and at a central position in the width direction of the sample. Drop the steel ball and check if the sample is broken. This test is repeated by changing the height at which the steel ball is dropped, and the impact strength is evaluated by setting the minimum height at which the sample is broken as the falling ball impact value. Therefore, the higher the falling ball impact value, the higher the impact strength. The maximum height for dropping the steel ball is set to 120 cm. Therefore, when the falling ball impact value exceeds 120 cm, the weight of the steel ball is changed to 534 g and 1044 g, and the falling ball impact value is measured in the same manner as described above. Convert to value.
(1) Falling ball impact value at 321 g = (534/321) × (falling ball impact value at 534 g)
(2) Falling ball impact value at 321 g = (1044/321) × (falling ball impact value at 1044 g)
In Examples and Comparative Examples, when the falling ball impact value is higher than 120 cm and less than 200 cm, it means the value converted by the above formula (1), and when it is 200 cm or more, the value converted by the above formula (2).

In the present invention,
(1) In the case of a foamed molded article having a falling ball impact value of 60 times and 30 cm or more: Pass (○)
(2) In the case of a foamed molded article having a falling ball impact value of 60 times and less than 30 cm: rejected (×)
(3) In the case of a foamed molded product having a falling ball impact value of 50 times and 40 cm or more: Pass (○)
(4) In the case of a foamed molded article having a falling ball impact value of 50 times and less than 40 cm: reject (×)
Is determined.

<Fusion rate of foam molding>
A 300 mm long and 5 mm deep cut line is placed on the surface of a rectangular parallelepiped foam molded body having a length of 400 mm, a width of 300 mm, and a height of 50 mm, and the foamed molded body is divided into two along the cut line. . Then, on the divided surface of the foam molded body, the number of foam particles broken (e) in the foam particles and the number of foam particles (f) broken at the interface between the foam particles are measured, The arrival rate is calculated.
Fusing rate (%) = 100 × (e) / [(e) + (f)]

In the present invention,
(1) When the fusion rate is 80% or more: Pass (○)
(2) When the fusion rate is less than 80%: Pass (○)
Is determined.

Example 1
LLDPE (product name “NF-444A” manufactured by Nippon Polyethylene Co., Ltd., melting point temperature: 119 ° C., melt flow rate: 2.0 g / synthesized from a non-crosslinked linear low density polyethylene resin using a metallocene catalyst 10 minutes, density: 0.912 g / cm ³ , Vicat softening temperature: 93 ° C.) and supplied to LLDPE. The supplied material was melt-kneaded and granulated by an underwater cutting method to obtain elliptical (egg-like) polyethylene resin particles (seed particles). The average weight of the polyethylene resin particles was 45 mg per 100 grains.

Next, 360 g of magnesium pyrophosphate (dispersant) and 5.6 g of sodium dodecylbenzenesulfonate (surfactant) were dispersed in 40 kg of water to obtain a dispersion medium.
A suspension was obtained by dispersing 8 kg of the polyethylene resin particles in a dispersion medium.
Furthermore, 10 g of dicumyl peroxide as a polymerization initiator was previously dissolved in 4 kg of styrene monomer.
After adjusting the temperature of the dispersion of the polyethylene resin particles to 60 ° C. and adding a styrene monomer containing a polymerization initiator over a period of 30 minutes, the polyethylene resin is stirred at a temperature of 60 ° C. for 30 minutes. The particles were impregnated with styrene monomer.
Next, the temperature of the dispersion was raised to 130 ° C. and held for 2 hours, and the styrene monomer was polymerized in the polyethylene resin particles to obtain resin particles.
Thereafter, the temperature was lowered to 115 ° C., and 45 g of sodium dodecylbenzenesulfonate was added to the suspension. Thereafter, 28 kg of a styrene monomer in which 112 g of t-butyl peroxybenzoate and 40 g of ethylenebisstearic acid amide were dissolved as a polymerization initiator was added dropwise over 6 hours.
After completion of the dropping, the temperature was maintained at 115 ° C. for 1 hour, and then the temperature was raised to 140 ° C. and maintained at that temperature for 3 hours to complete the polymerization. Then, it cooled to normal temperature and took out the composite resin particle.

Subsequently, 15 kg of composite resin particles and 75 g of diisobutyl adipate were supplied to a pressure-resistant V-type rotary mixer having an internal volume of 1 m ³ and rotated, butane was used as a volatile blowing agent at normal temperature as butane (normal butane: isobutane = 7: 3, mass ratio) 2.25 kg was press-fitted. Thereafter, the temperature was raised to 70 ° C. and held for 4 hours, and then cooled to 25 ° C. to obtain expandable composite resin particles.

  The obtained expandable composite resin particles were immediately supplied to a pre-foaming machine, and pre-foamed particles were produced by introducing pre-foam by introducing steam at a pressure of 0.01 MPa.

  Next, the pre-expanded particles are filled in the mold of the foam molding machine, and then steam (steam pressure: 0.06 MPa, steam temperature 112 ° C.) is heated for 5 seconds on one side, reversely 2 seconds for heating, and 15 seconds for both sides heating. Then, the pre-expanded particles were subjected to foam molding, and after 300 seconds of water cooling and 150 seconds of vacuum cooling, a 300 × 400 × 50 mm rectangular solid foam molded body was obtained. The falling ball impact value and the like of the obtained foamed molded product were measured.

About composite resin particles
(1) The average particle diameter was 1.3 mm.

About expandable composite resin particles
(1) The foaming agent is contained in an amount of 8.5 parts by mass with respect to 100 parts by mass of the expandable composite resin particles.
(2) The average particle size was 1.3 mm.

About pre-expanded particles
(1) Bulk multiple is 62 times,
(2) The average particle size was 4.3 mm.

Example 2
LLDPE (product name "SP2020" manufactured by Prime Polymer Co., Ltd., melting point temperature: 116 ° C, melt flow rate: 2.3 g / 10 minutes) synthesized from a non-crosslinked linear low density polyethylene resin using a metallocene catalyst , Density: 0.916 g / cm ³ , Vicat softening temperature: 93 ° C.) and supplied to LLDPE. The supplied material was melt-kneaded and granulated by an underwater cutting method to obtain elliptical (egg-like) polyethylene resin particles (seed particles). The average weight of the polyethylene resin particles was 45 mg per 100 grains.

Next, 360 g of magnesium pyrophosphate (dispersant) and 5.6 g of sodium dodecylbenzenesulfonate (surfactant) were dispersed in 40 kg of water to obtain a dispersion medium.
A suspension was obtained by dispersing 8 kg of the polyethylene resin particles in a dispersion medium.
Furthermore, 10 g of dicumyl peroxide as a polymerization initiator was previously dissolved in 4 kg of styrene monomer.
After adjusting the temperature of the dispersion of the polyethylene resin particles to 60 ° C. and adding a styrene monomer containing a polymerization initiator over a period of 30 minutes, the polyethylene resin is stirred at a temperature of 60 ° C. for 30 minutes. The particles were impregnated with styrene monomer.
Next, the temperature of the dispersion was raised to 130 ° C. and held for 2 hours, and the styrene monomer was polymerized in the polyethylene resin particles to obtain resin particles.
Thereafter, the temperature was lowered to 115 ° C., and 45 g of sodium dodecylbenzenesulfonate was added to the suspension. Thereafter, 28 kg of a styrene monomer in which 112 g of t-butyl peroxybenzoate and 40 g of ethylenebisstearic acid amide were dissolved as a polymerization initiator was added dropwise over 6 hours.
After completion of the dropping, the temperature was maintained at 115 ° C. for 1 hour, and then the temperature was raised to 140 ° C. and maintained at that temperature for 3 hours to complete the polymerization. Then, it cooled to normal temperature and took out the composite resin particle.

Subsequently, while supplying 15 kg of composite resin particles and 75 g of diisobutyl adipate to a pressure-resistant V-type rotary mixer having an internal volume of 1 m ³ and rotating the mixture, butane (normal butane: isobutane = 7: 3) as a volatile blowing agent at room temperature. , Mass ratio) 2.25 kg was injected. Thereafter, the temperature was raised to 70 ° C. and held for 4 hours, and then cooled to 25 ° C. to obtain expandable composite resin particles.

  The obtained expandable composite resin particles were immediately supplied to a pre-foaming machine, and pre-foamed particles were produced by introducing pre-foam by introducing steam at a pressure of 0.01 MPa.

  Next, the pre-expanded particles are filled in the mold of the foam molding machine, and then steam (steam pressure: 0.06 MPa, steam temperature 112 ° C.) is heated for 5 seconds on one side, reversely 2 seconds for heating, and 15 seconds for both sides heating. Then, the pre-expanded particles were subjected to foam molding, and after 300 seconds of water cooling and 150 seconds of vacuum cooling, a 300 × 400 × 50 mm rectangular solid foam molded body was obtained. The falling ball impact value and the like of the obtained foamed molded product were measured.

  The average particle size of the composite resin particles was 1.3 mm.

About expandable composite resin particles
(1) The foaming agent is contained in an amount of 8.6 parts by mass with respect to 100 parts by mass of the foamable composite resin particles.
(2) The average particle size was 1.3 mm.

About pre-expanded particles
(1) Bulk multiple is 62 times,
(2) The average particle size was 4.3 mm.

Example 3
LLDPE (product name “SP-1020”, manufactured by Prime Polymer Co., Ltd., melting point temperature: 111 ° C., melt flow rate: 2.0 g / synthesized from a non-crosslinked linear low density polyethylene resin using a metallocene catalyst 10 minutes, density: 0.909 g / cm ³ , Vicat softening temperature: 92 ° C.) and supplied to LLDPE. The supplied material was melt-kneaded and granulated by an underwater cutting method to obtain elliptical (egg-like) polyethylene resin particles (seed particles). The average weight of the polyethylene resin particles was 45 mg per 100 grains.

Next, 360 g of magnesium pyrophosphate (dispersant) and 5.6 g of sodium dodecylbenzenesulfonate (surfactant) were dispersed in 40 kg of water to obtain a dispersion medium.
A suspension was obtained by dispersing 8 kg of the polyethylene resin particles in a dispersion medium.
Furthermore, 10 g of dicumyl peroxide as a polymerization initiator was previously dissolved in 4 kg of styrene monomer.
After adjusting the temperature of the dispersion of the polyethylene resin particles to 60 ° C. and adding a styrene monomer containing a polymerization initiator over a period of 30 minutes, the polyethylene resin is stirred at a temperature of 60 ° C. for 30 minutes. The particles were impregnated with styrene monomer.
Next, the temperature of the dispersion was raised to 130 ° C. and held for 2 hours, and the styrene monomer was polymerized in the polyethylene resin particles to obtain resin particles.
Thereafter, the temperature was lowered to 115 ° C., and 45 g of sodium dodecylbenzenesulfonate was added to the suspension. Thereafter, 28 kg of a styrene monomer in which 112 g of t-butyl peroxybenzoate and 40 g of ethylenebisstearic acid amide were dissolved as a polymerization initiator was added dropwise over 6 hours.
After completion of the dropping, the temperature was maintained at 115 ° C. for 1 hour, and then the temperature was raised to 140 ° C. and maintained at that temperature for 3 hours to complete the polymerization. Then, it cooled to normal temperature and took out the composite resin particle.

Subsequently, while supplying 15 kg of composite resin particles and 75 g of diisobutyl adipate to a pressure-resistant V-type rotary mixer having an internal volume of 1 m ³ and rotating the mixture, butane (normal butane: isobutane = 7: 3) as a volatile blowing agent at room temperature. , Mass ratio) 2.25 kg was injected. Thereafter, the temperature was raised to 70 ° C. and held for 4 hours, and then cooled to 25 ° C. to obtain expandable composite resin particles.

  The obtained expandable composite resin particles were immediately supplied to a pre-foaming machine, and pre-foamed particles were produced by introducing pre-foam by introducing steam at a pressure of 0.01 MPa.

  Next, the pre-expanded particles are filled in the mold of the foam molding machine, and then steam (steam pressure: 0.06 MPa, steam temperature 112 ° C.) is heated for 5 seconds on the one hand, reversely heated for 2 seconds, and heated on both sides for 15 seconds. Then, the pre-expanded particles were subjected to foam molding, and after 300 seconds of water cooling and 150 seconds of vacuum cooling, a 300 × 400 × 50 mm rectangular solid foam molded body was obtained. The falling ball impact value and the like of the obtained foamed molded product were measured.

  The average particle diameter of the composite resin particles was 1.3 mm.

About expandable composite resin particles
(1) The foaming agent is included in an amount of 9.5 parts by mass with respect to 100 parts by mass of the expandable composite resin particles.
(2) The average particle size was 1.3 mm.

About pre-expanded particles
(1) Bulk multiple is 62 times,
(2) The average particle size was 4.3 mm.

Example 4
LLDPE (product name “NF-444A” manufactured by Nippon Polyethylene Co., Ltd., melting point temperature: 119 ° C., melt flow rate: 2.0 g / synthesized from a non-crosslinked linear low density polyethylene resin using a metallocene catalyst 10 minutes, density: 0.912 g / cm ³ , Vicat softening temperature: 93 ° C.), LLDPE 25.0 kg, and masterbatch containing 30% by weight of furnace black (product name “MHRB-013” manufactured by UI Corporation) 5.0 kg Were melt-kneaded and granulated by an underwater cutting method to obtain carbon black-containing polyethylene resin particles (seed particles) having an oval spherical egg shape. The average weight of the carbon black-containing polyethylene resin particles containing 5 parts by mass of carbon black with respect to 100 parts by mass of the resin particles was 45 mg per 100 particles.

Next, 360 g of magnesium pyrophosphate (dispersant) and 5.6 g of sodium dodecylbenzenesulfonate (surfactant) were dispersed in 40 kg of water to obtain a dispersion medium.
A suspension was obtained by dispersing 12 kg of the carbon black-containing polyethylene resin particles in a dispersion medium.
Furthermore, 12 g of dicumyl peroxide as a polymerization initiator was previously dissolved in 6 kg of styrene monomer.
By adjusting the temperature of the dispersion of the carbon black-containing polyethylene resin particles to 60 ° C., adding a styrene monomer containing a polymerization initiator over a period of 30 minutes, and then stirring at a temperature of 60 ° C. for 30 minutes. Carbon black-containing polyethylene resin particles were impregnated with a styrene monomer.
Next, the temperature of the dispersion was raised to 130 ° C. and held for 2 hours, and the styrene monomer was polymerized in the carbon black-containing polyethylene resin particles to obtain resin particles.
Thereafter, the temperature was lowered to 125 ° C., and 45 g of sodium dodecylbenzenesulfonate was added to the suspension. Thereafter, 22 kg of styrene monomer in which 84 g of dicumyl peroxide and 40 g of ethylenebisstearic acid amide were dissolved as a polymerization initiator was added dropwise over 4 hours.
After completion of the dropwise addition, the temperature was maintained at 125 ° C. for 1 hour, then heated to 140 ° C. and maintained at that temperature for 3 hours to complete the polymerization. Then, it cooled to normal temperature and took out the carbon black containing composite resin particle.

Subsequently, while supplying 15 kg of carbon black-containing composite resin particles and 75 g of diisobutyl adipate to a pressure-resistant V-type rotary mixer having an internal volume of 1 m ³ and rotating the mixture, butane (normal butane: isobutane = 7: 3, mass ratio) 2.50 kg was injected. Thereafter, the temperature was raised to 70 ° C. and held for 4 hours, and then cooled to 25 ° C. to obtain expandable composite resin particles.

  The obtained expandable carbon black-containing composite resin particles were immediately supplied to a pre-foaming machine, and pre-foamed particles were produced by introducing pre-foam by introducing steam at a pressure of 0.01 MPa.

  Next, the pre-expanded particles are filled in the mold of the foam molding machine, and then steam (steam pressure: 0.06 MPa, steam temperature 112 ° C.) is heated for 5 seconds on one side, reversely 2 seconds for heating, and 15 seconds for both sides heating. Then, the pre-expanded particles were subjected to foam molding, and after 300 seconds of water cooling and 150 seconds of vacuum cooling, a 300 × 400 × 50 mm rectangular solid foam molded body was obtained. The falling ball impact value and the like of the obtained foamed molded product were measured.

  The average particle size of the carbon black-containing composite resin particles was 1.2 mm.

About foamable carbon black-containing composite resin particles
(1) The foaming agent is contained in an amount of 10.1 parts by mass with respect to 100 parts by mass of the expandable carbon black-containing composite resin particles.
(2) The average particle diameter was 1.2 mm.

About pre-expanded particles
(1) Bulk multiple is 62 times,
(2) The average particle size was 4.0 mm.

Example 5
LLDPE (product name “NF-444A” manufactured by Nippon Polyethylene Co., Ltd., melting point temperature: 119 ° C., melt flow rate: 2.0 g / synthesized from a non-crosslinked linear low density polyethylene resin using a metallocene catalyst 10 minutes, density: 0.912 g / cm ³ , Vicat softening temperature: 93 ° C.) and supplied to LLDPE. The supplied material was melt-kneaded and granulated by an underwater cutting method to obtain elliptical (egg-like) polyethylene resin particles (seed particles). The average weight of the polyethylene resin particles was 45 mg per 100 grains.

Next, 360 g of magnesium pyrophosphate (dispersant) and 5.6 g of sodium dodecylbenzenesulfonate (surfactant) were dispersed in 40 kg of water to obtain a dispersion medium.
A suspension was obtained by dispersing 8 kg of the polyethylene resin particles in a dispersion medium.
Furthermore, 10 g of dicumyl peroxide as a polymerization initiator was previously dissolved in 4 kg of styrene monomer.
After adjusting the temperature of the dispersion of the polyethylene resin particles to 60 ° C. and adding a styrene monomer containing a polymerization initiator over a period of 30 minutes, the polyethylene resin is stirred at a temperature of 60 ° C. for 30 minutes. The particles were impregnated with styrene monomer.
Next, the temperature of the dispersion was raised to 130 ° C. and held for 2 hours, and the styrene monomer was polymerized in the polyethylene resin particles to obtain resin particles.
Thereafter, the temperature was lowered to 115 ° C., and 45 g of sodium dodecylbenzenesulfonate was added to the suspension. Thereafter, 112 kg of t-butyl peroxybenzoate as a polymerization initiator and 28 kg of styrene monomer in which 40 g of ethylenebisstearic acid amide was dissolved and 0.8 kg of butyl acrylate monomer were added dropwise over 6 hours.
After completion of the dropping, the temperature was maintained at 115 ° C. for 1 hour, and then the temperature was raised to 140 ° C. and maintained at that temperature for 3 hours to complete the polymerization. Then, it cooled to normal temperature and took out the composite resin particle.

Subsequently, 15 kg of composite resin particles and 135 g of diisobutyl adipate were supplied to a pressure-resistant V-type rotary mixer having an internal volume of 1 m ³ , and 2.55 kg of isopentane was injected as a volatile blowing agent at room temperature. Thereafter, the temperature was raised to 70 ° C. and held for 4 hours, and then cooled to 25 ° C. to obtain expandable composite resin particles.

  The obtained expandable composite resin particles were immediately supplied to a pre-foaming machine, and pre-foamed particles were produced by introducing pre-foam by introducing steam at a pressure of 0.01 MPa.

  Next, the pre-expanded particles are filled in the mold of the foam molding machine, and then steam (steam pressure: 0.06 MPa, steam temperature 112 ° C.) is heated for 5 seconds on the one hand, reversely heated for 2 seconds, and heated on both sides for 15 seconds. Then, the pre-expanded particles were subjected to foam molding, and after 300 seconds of water cooling and 150 seconds of vacuum cooling, a 300 × 400 × 50 mm rectangular solid foam molded body was obtained. The falling ball impact value and the like of the obtained foamed molded product were measured.

  The average particle size of the composite resin particles was 1.3 mm.

About expandable composite resin particles
(1) The foaming agent is contained in an amount of 10.1 parts by mass with respect to 100 parts by mass of the foamable composite resin particles.
(2) The average particle size was 1.3 mm.

About pre-expanded particles
(1) Bulk multiple is 62 times,
(2) The average particle size was 4.3 mm.

Comparative Example 1
LLDPE (product name “SP1520”, manufactured by Prime Polymer Co., Ltd., melting point temperature: 116 ° C., melt flow rate: 2.0 g / 10 minutes) synthesized from a non-crosslinked linear low density polyethylene resin using a metallocene catalyst , Density: 0.913 g / cm ³ , Vicat softening temperature: 96 ° C.) and supplied to LLDPE. The feed was melt-kneaded and granulated by an underwater cutting method to obtain oval-spherical egg-shaped polyethylene resin particles (seed particles). The average weight of the polyethylene resin particles was 45 mg per 100 grains.

Next, 360 g of magnesium pyrophosphate (dispersant) and 5.6 g of sodium dodecylbenzenesulfonate (surfactant) were dispersed in 40 kg of water to obtain a dispersion medium.
A suspension was obtained by dispersing 8 kg of the polyethylene resin particles in a dispersion medium.
Furthermore, 10 g of dicumyl peroxide as a polymerization initiator was previously dissolved in 4 kg of styrene monomer.
After adjusting the temperature of the dispersion of the polyethylene resin particles to 60 ° C. and adding a styrene monomer containing a polymerization initiator over a period of 30 minutes, the polyethylene resin is stirred at a temperature of 60 ° C. for 30 minutes. The particles were impregnated with styrene monomer.
Next, the temperature of the dispersion was raised to 130 ° C. and held for 2 hours, and the styrene monomer was polymerized in the polyethylene resin particles to obtain resin particles.
Thereafter, the temperature was lowered to 115 ° C., and 45 g of sodium dodecylbenzenesulfonate was added to the suspension. Thereafter, 28 kg of a styrene monomer in which 112 g of t-butyl peroxybenzoate and 40 g of ethylenebisstearic acid amide were dissolved as a polymerization initiator was added dropwise over 6 hours.
After completion of the dropping, the temperature was maintained at 115 ° C. for 1 hour, and then the temperature was raised to 140 ° C. and maintained at that temperature for 3 hours to complete the polymerization. Then, it cooled to normal temperature and took out the composite resin particle.

Subsequently, 15 kg of composite resin particles and 75 g of diisobutyl adipate were supplied to a pressure-resistant V-type rotary mixer having an internal volume of 1 m ³ and rotated, butane was used as a volatile blowing agent at normal temperature as butane (normal butane: isobutane = 7: 3, mass ratio) 2.25 kg was press-fitted. Thereafter, the temperature was raised to 70 ° C. and held for 4 hours, and then cooled to 25 ° C. to obtain expandable composite resin particles.

  The obtained expandable composite resin particles were immediately supplied to a pre-foaming machine, and pre-foamed particles were produced by introducing pre-foam by introducing steam at a pressure of 0.01 MPa. However, 60 times or more pre-expanded particles could not be obtained.

  Next, the pre-expanded particles are filled in the mold of the foam molding machine, and then steam (steam pressure: 0.06 MPa, steam temperature 112 ° C.) is heated for 5 seconds on one side, reversely 2 seconds for heating, and 15 seconds for both sides heating. Then, the pre-expanded particles were subjected to foam molding, and after 300 seconds of water cooling and 150 seconds of vacuum cooling, a 300 × 400 × 50 mm rectangular solid foam molded body was obtained. The falling ball impact value and the like of the obtained foamed molded product were measured.

  The average particle size of the composite resin particles was 1.3 mm.

About expandable composite resin particles
(1) The foaming agent is included in an amount of 8.9 parts by mass with respect to 100 parts by mass of the expandable composite resin particles.
(2) The average particle size was 1.3 mm.

About pre-expanded particles
(1) Bulk multiple is 52 times,
(2) The average particle size was 4.0 mm.

Comparative Example 2
A non-crosslinked linear low-density polyethylene resin synthesized using a metallocene catalyst, LLDPE (manufactured by Nihon Unicar, product name “FMRN-063”, melting point temperature: 124 ° C., melt flow rate: 1.3 g / 10 minutes, density: 0.914 g / cm ³ , Vicat softening temperature: 97 ° C.) and supplied to LLDPE. The feed was melt-kneaded and granulated by an underwater cutting method to obtain oval-spherical egg-shaped polyethylene resin particles (seed particles). The average weight of the polyethylene resin particles was 45 mg per 100 grains.

Next, 360 g of magnesium pyrophosphate (dispersant) and 5.6 g of sodium dodecylbenzenesulfonate (surfactant) were dispersed in 40 kg of water to obtain a dispersion medium.
A suspension was obtained by dispersing 8 kg of the polyethylene resin particles in a dispersion medium.
Furthermore, 10 g of dicumyl peroxide as a polymerization initiator was previously dissolved in 4 kg of styrene monomer.
After adjusting the temperature of the dispersion of the polyethylene resin particles to 60 ° C. and adding a styrene monomer containing a polymerization initiator over a period of 30 minutes, the polyethylene resin is stirred at a temperature of 60 ° C. for 30 minutes. The particles were impregnated with styrene monomer.
Next, the temperature of the dispersion was raised to 130 ° C. and held for 2 hours, and the styrene monomer was polymerized in the polyethylene resin particles to obtain particles.
Thereafter, the temperature was lowered to 115 ° C., and 45 g of sodium dodecylbenzenesulfonate was added to the suspension. Thereafter, 28 kg of a styrene monomer in which 112 g of t-butyl peroxybenzoate and 40 g of ethylenebisstearic acid amide were dissolved as a polymerization initiator was added dropwise over 6 hours.

  After completion of the dropping, the temperature was maintained at 115 ° C. for 1 hour, and then the temperature was raised to 140 ° C. and maintained at that temperature for 3 hours to complete the polymerization. Then, it cooled to normal temperature and took out the composite resin particle.

Subsequently, while supplying 15 kg of composite resin particles and 75 g of diisobutyl adipate to a pressure-resistant V-type rotary mixer having an internal volume of 1 m ³ and rotating the mixture, butane (normal butane: isobutane = 7: 3) as a volatile blowing agent at room temperature. , Mass ratio) 2.25 kg was injected. Thereafter, the temperature was raised to 70 ° C. and held for 4 hours, and then cooled to 25 ° C. to obtain expandable composite resin particles.

  The obtained expandable composite resin particles were immediately supplied to a pre-foaming machine, and pre-foamed particles were produced by introducing pre-foam by introducing steam at a pressure of 0.01 MPa. However, 60 times or more pre-expanded particles could not be obtained.

  Next, the pre-expanded particles are filled in the mold of the foam molding machine, and then steam (steam pressure: 0.06 MPa, steam temperature 112 ° C.) is heated for 5 seconds on the one hand, reversely heated for 2 seconds, and heated on both sides for 15 seconds. Then, the pre-expanded particles were subjected to foam molding, and after 300 seconds of water cooling and 150 seconds of vacuum cooling, a 300 × 400 × 50 mm rectangular solid foam molded body was obtained. The falling ball impact value and the like of the obtained foamed molded product were measured.

  The average particle size of the composite resin particles was 1.3 mm.

About expandable composite resin particles
(1) The foaming agent is included in an amount of 8.9 parts by mass with respect to 100 parts by mass of the expandable composite resin particles.
(2) The average particle size was 1.3 mm.

About pre-expanded particles
(1) Bulk multiple is 52 times,
(2) The average particle size was 4.0 mm.

In Table 1, the raw material seed | species and evaluation result of an Example and a comparative example are explained in full detail.
Moreover, the evaluation result of the foamability of an Example and a comparative example is shown in FIG.

  From Table 1, good results were shown for multiples, fusion rates, and falling ball impact values for Examples, but good results were not shown for Comparative Examples.

  Therefore, the foamed molded product of the present invention is a foamed molded product having a high multiple and excellent impact resistance. For this reason, the foaming molding of this invention can be used widely as a structural member, a building member, etc. in the motor vehicle field | area, and can also be especially used as a shock absorbing material for household appliances.

A1 Bulk multiple (times)
A2 Heating time (seconds)
A3 Example 1
A4 Example 4
A5 Example 5
A6 Comparative Example 1
A7 Comparative Example 2

Claims (9)

As a resin component, it contains 100 parts by mass of polyethylene resin and 200 to 900 parts by mass of polystyrene resin,
The polyethylene-based resin has a density of 0.900 to 0.916 g / cm ³ , a melt flow rate of 1.0 to 5.0 g / 10 min measured under a load of 190 ° C. and 2.16 kg, and 88 to 95. A composite resin particle having a Vicat softening temperature of ° C.   The composite resin particle according to claim 1, wherein the composite resin particle contains carbon black.   The composite resin particle according to claim 1, wherein the composite resin particle is obtained by seed polymerizing a styrene monomer to the polyethylene resin.   Expandable composite resin particles obtained from the composite resin particles according to any one of claims 1 to 3.   The expandable composite resin particle according to claim 4, wherein the expandable composite resin particle exhibits two foam peaks when the expandable composite resin particle is allowed to stand at 90 to 100 ° C. for 300 seconds.   Pre-expanded particles obtained from the expandable composite resin particles according to claim 4 or 5.   The pre-expanded particles according to claim 6, wherein the pre-expanded particles have a bulk multiple of 55 times or more.   A foam-molded article obtained from the pre-expanded particles according to claim 6 or 7.   The foamed molded product according to claim 8, wherein the foamed molded product has a multiple of 55 times or more.

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