TW201835197A - Composite resin particles and composite resin foam particles obtained by impregnating a vinyl resin with a styrene-based monomer and through polymerization process - Google Patents

Abstract

An object of the present invention is to provide a composite resin particle and a composite resin foam particle which are excellent in compression rigidity and flexural resistance and capable of suppressing breakage due to deformation. The solution is to provide a composite resin particle obtained by impregnating an ethylene-based resin with a styrene-based monomer and polymerizing it, and further, provide a composite resin foam particle using a composite resin as a base resin. The content ratio of the component derived from the styrene-based monomer, with respect to 100 parts by mass of the ethylene-based resin, is more than 400 parts by mass and not more than 1900 parts by mass. The composite resin particles have an average aspect ratio of 1.30 or less. The 63% volume average particle diameter d63, the 90% volume average particle diameter d90, and the 10% volume average particle diameter d10 of the composite resin particles satisfy the following formulas I and II.

Description

Composite resin particles and composite resin foamed particles

The present invention relates to composite resin particles of an ethylene-based resin and a styrene-based resin obtained by impregnating a particle containing an ethylene-based resin with a polymerized styrene monomer, and composite resin foamed particles using the composite resin as a base resin.

The foamed particle molded body utilizes its excellent characteristics such as cushioning, lightness, vibration resistance, sound insulation, and heat insulation, and is used in a wide range of applications such as packaging materials, construction materials, and vehicle components. The expanded particle forming system is obtained by fusing a plurality of expanded particles to each other in a forming mold. In addition, the foamed particles are resin particles obtained by impregnating an organic physical foaming agent such as propane, butane, and pentane, or an inorganic physical foaming agent such as carbon dioxide, nitrogen, and air by impregnating the resin particles with heating. Obtained from foam. As a resin component constituting the expanded particle molded body, a styrene resin, an acrylic resin, a vinyl resin, or the like is mainly used.

In particular, packaging containers used for plate-shaped products such as liquid crystal panels and solar power generation panels can be used multiple times because they are less prone to crushing or abrasion, cracking, and defects caused by abrasion. A foamed particle molded body made of a resin. However, with the expansion of the panel size in recent years, the packing weight has also increased. Therefore, when a foamed particle molded body made of an acrylic resin is used as a packing container, the amount of deflection in the packing state increases. Great tendency. If the amount of deflection at the time of packing is too large, the container may fall off from the shipping equipment or the panel may be damaged due to deflection when the container is lifted at both ends of the container that supports the packing state.

On the other hand, attention has been paid to a foamed particle molded body composed of a composite resin of a vinyl resin and a styrene resin (refer to Patent Documents 1 to 3). Such a foamed particle forming system composed of a composite resin is produced, for example, by foaming composite resin particles as described above and fusing them with each other. The composite resin particles are made by styrene-based monomers. The body is obtained by impregnating and polymerizing core particles containing a vinyl resin. In the thus-obtained expanded particle molded article, rigidity can be improved by increasing the proportion of the styrene-based resin component in the composite resin. As a result, the amount of deflection of the foamed particle molded body can be reduced, and the deflection resistance can be improved. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2014-196441 [Patent Document 2] Japanese Patent Laid-Open No. 2014-196444 [Patent Document 3] Japanese Patent No. 5058866

[Problems to be Solved by the Invention]

However, a foamed particle molded body composed of a composite resin has a smaller bending fracture energy than a foamed particle molded body composed of an acrylic resin. In particular, when the proportion of the styrene-based resin component in the composite resin is increased in order to increase the rigidity of the foamed particle molded body, even if the foamed particles are strongly fused to each other, the foamed particle molded body will still occur once a sharp load change occurs. Risk of rupture. In particular, in the case of a packaging container, the formed bodies in a packed state may be stacked or moved, and at this time, the formed bodies are liable to undergo a drastic load change. When such a foamed particle molded body composed of a composite resin having a high proportion of styrene-based resin components is used in a packaging container, the foamed particles formed from an acrylic resin are different from the disposal method depending on the disposal method. The formed body is more likely to crack than the formed body.

The present invention has been made in view of the background, and it is intended to provide composite resin particles and composite resin hairs that can obtain a foamed composite resin molded body that is excellent in compressive rigidity and flex resistance, and that can suppress breakage caused by deformation. Bubble particles. [Means for solving problems]

One aspect of the present invention resides in a composite resin particle, which is a composite resin particle obtained by impregnating a particle containing a vinyl resin with a polymerized styrene monomer, and the above styrene-based monomer is 100 parts by mass of the vinyl resin. The content ratio of the components is more than 400 parts by mass and 1900 parts by mass or less, the average aspect ratio of the composite resin particles is 1.30 or less, and the 63% volume average particle diameter d63, 90% volume average particle diameter d90, And the 10% volume average particle diameter d10 satisfies the relationship of the following formula I and formula II:

Another aspect of the present invention resides in a composite resin expanded particle, which is a composite resin expanded particle in which a composite resin obtained by impregnating a vinyl resin with a polymerized styrene monomer is used as a base resin. The content ratio of the component derived from the styrene-based monomer is more than 400 parts by mass and 1900 parts by mass or less, the average aspect ratio of the composite resin expanded particles is 1.30 or less, and the apparent density of the composite resin expanded particles Da, 63% volume average particle diameter d63, 90% volume average particle diameter d90, and 10% volume average particle diameter d10 satisfy the relationship of the following formulas III to V: [Effect of the invention]

Although the composite resin particles are composed of composite resins with a high content ratio of components derived from styrene monomers as described above, the average aspect ratio is relatively small, and the 63% volume average particle diameter is adjusted as shown in Formula I. On a smaller scale. Moreover, it satisfies Formula II, and the dispersion degree of the average particle diameter of a composite resin particle is small. Therefore, the composite resin foamed particles obtained by foaming the composite resin particles can obtain a foamed composite resin molded body which is excellent in compressive rigidity and flex resistance and can suppress breakage due to deformation.

Although the composite resin expanded particles are as described above, although the composite resin containing a styrene-based monomer-containing component as a base resin is used as the base resin, the average aspect ratio is relatively small, and the apparent density is as shown in Formula III. Adjusted to the established range. Furthermore, since the composite resin expanded particle system satisfies Formula IV, the average particle diameter is small, and it satisfies Formula V, and the dispersion degree of the average particle diameter of the composite resin particles is small. Therefore, the foamed composite resin particles can obtain a foamed composite resin molded body which is excellent in compressive rigidity and flex resistance, and can suppress breakage due to deformation.

As described above, according to the above aspect, it is possible to provide composite resin particles and composite resin foam particles that can obtain a foamed composite resin molded body that is excellent in compressive rigidity and flex resistance and can suppress breakage due to deformation. .

[Form of Implementing Invention]

Next, preferred embodiments of the composite resin particles and the composite resin foamed particles will be described. The composite resin particles can be used to produce composite resin foamed particles (hereinafter referred to as "foamed particles") by impregnating and foaming a physical foaming agent. As the physical foaming agent, an inorganic physical foaming agent such as carbon dioxide may be used, or an organic physical foaming agent such as a hydrocarbon may be used. In addition, the foamed particles obtained by foaming are subjected to in-mold molding to produce a molded body (that is, a foamed composite resin molded body) in which foamed particles are fused to each other.

[Composite resin particles] The composite resin particles are made by impregnating a vinyl resin with a polymerized styrene monomer, and are a composite resin containing a vinyl resin and a styrene resin. In this specification, the composite resin is a resin obtained by impregnating a vinyl resin with a styrene monomer or the like and polymerizing the resin, and is a resin containing a component derived from a vinyl resin and a component derived from a styrene monomer. .

In general, the main component of the component derived from a styrene-based monomer is a styrene-based resin obtained by polymerizing a styrene-based monomer. In the polymerization of styrene-based monomers, in addition to the polymerization of styrene-based monomers, graft polymerization of styrene-based monomers occurs in the polymer chain constituting the vinyl resin. At this time, the composite resin contains not only a styrene-based resin component obtained by polymerizing an ethylene-based resin component and a styrene-based monomer, but also a vinyl-based resin component obtained by graft polymerization of a styrene-based monomer (that is, PE-g). -PS composition). In addition, during the polymerization of the styrene-based monomer, cross-linking of the vinyl-based resin may occur; in this case, the composite resin system contains uncrosslinked vinyl-based resin and cross-linked vinyl-based resin as the vinyl-based resin component. . Therefore, the composite resin is different from the concept of a mixed resin obtained by melt-kneading a polymerized ethylene-based resin and a polymerized styrene-based resin.

The content ratio of the composite resin particles with respect to 100 parts by mass of the styrene-based monomer component of the vinyl resin is more than 400 parts by mass. When the content ratio of the component derived from the styrene-based monomer is 400 parts by mass or less, the rigidity of the foamed composite resin molded body obtained by using the composite resin particles may be reduced, and the flexibility resistance may be insufficient. From the viewpoint of further improving rigidity and further improving flex resistance, the content of the component derived from the styrene-based monomer is preferably 450 parts by mass or more, and more preferably 500 parts by mass or more.

The content of the styrene-based monomer-based component relative to 100 parts by mass of the ethylene-based resin is 1900 parts by mass or less. When the content of the component derived from the styrene-based monomer exceeds 1900 parts by mass, the foamed composite resin molded body obtained by using the composite resin particles is likely to be broken and may be brittle. From the viewpoint of further suppressing cracking of the foamed composite resin molded body, the blending amount of the styrene-based monomer is preferably 1500 parts by mass or less, more preferably 900 parts by mass or less, and still more preferably 600 parts by mass or less.

As the vinyl-based resin, for example, linear low-density polyethylene, branched low-density polyethylene, high-density polyethylene, ethylene-acrylic copolymer, ethylene-acrylic acid alkyl ester copolymer, and ethylene-methacrylic acid alkyl can be used. Ester copolymers, ethylene-vinyl acetate copolymers, and the like. The vinyl resin may be a single polymer, but a mixture of two or more polymers may be used.

The ethylene-based resin preferably contains a linear low-density polyethylene as a main component. More specifically, the content of the linear low-density polyethylene in the vinyl resin is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. The linear low-density polyethylene is preferably a branched structure having a linear polyethylene chain and a short-chain branched chain having 2 to 6 carbon atoms. Specific examples include ethylene-butene copolymer, ethylene-hexene copolymer, and ethylene-octene copolymer.

The vinyl resin is particularly preferably a linear low-density polyethylene polymerized using a metallocene-based polymerization catalyst. At this time, the affinity of the ethylene-based resin component in the composite resin particles and the styrene-based resin component polymerized with the styrene-based monomer is further improved, and composite resin particles having higher toughness can be obtained. In addition, since the low-molecular-weight component can be further reduced, the fusion strength between the foamed particles at the time of molding can be further improved, and a foamed composite resin molded body that is less prone to cracking can be produced. In addition, a foamed composite resin molded body having a higher level of excellent rigidity of a styrene resin and excellent adhesion of a vinyl resin can be obtained.

The melting point Tm of the vinyl resin is preferably 90 to 105 ° C. In this case, since the styrene-based monomer can be sufficiently impregnated with the vinyl-based resin during the production of the composite resin particles, it is possible to prevent the suspension system from becoming unstable during polymerization. As a result, it is possible to obtain a foamed composite resin molded body having a higher level of both excellent rigidity of a styrene resin and excellent adhesion of a vinyl resin. From the same viewpoint, the melting point Tm of the vinyl resin is more preferably 95 to 105 ° C, and still more preferably 100 to 105 ° C. The melting point Tm can be measured by differential scanning calorimetry (DSC) based on JIS K7121 (1987). Regarding the condition adjustment of the test piece, "(2) the case where a certain heat treatment is used and the melting temperature is adopted", the heating temperature and the cooling temperature are both set to 10 ° C / min.

The styrene-based monomer may include, in addition to styrene, a monomer copolymerizable with styrene. Examples of the monomer copolymerizable with styrene include styrene derivatives and other vinyl monomers. Examples of the styrene derivative include α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, and 2,4-dimethyl. Styrene, p-methoxystyrene, p-n-butylstyrene, p-tertiary butylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2, 4, 6-tribromostyrene, divinylbenzene, styrene sulfonic acid, sodium styrene sulfonate, etc. These can be used alone or in combination of two or more.

Examples of other vinyl monomers include acrylate, methacrylate, acrylic acid, methacrylic acid, hydroxyl-containing vinyl compounds, nitrile-group-containing vinyl compounds, organic acid vinyl compounds, olefin compounds, diene compounds, Halogenated ethylene compounds, halogenated vinylidene compounds, maleimide compounds, and the like. These vinyl monomers can be used alone or in combination of two or more.

Examples of the acrylate include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Examples of the methacrylate include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate.

Examples of the hydroxy-containing ethylene compound include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate. Examples of the nitrile group-containing ethylene compound include acrylonitrile and methacrylonitrile. Examples of the organic acid vinyl compound include vinyl acetate and vinyl propionate.

Examples of the olefin compound include ethylene, propylene, 1-butene, and 2-butene. Examples of the diene compound include butadiene, isoprene, and chloroprene. Examples of the halogenated ethylene compound include vinyl chloride and vinyl bromide. Examples of the halogenated vinylidene compound include vinylidene chloride. Examples of the maleimide compound include N-phenylmaleimide and N-methylmaleimide.

From the viewpoint of improving the foamability of the composite resin particles, a styrene-based monomer is preferably styrene alone or a combination of styrene and an acrylic monomer. From the viewpoint of further improving foamability, styrene and butyl acrylate are particularly preferably used in terms of styrene-based monomers. At this time, regarding the blending amount of butyl acrylate, the content of the butyl acrylate component in the composite resin is preferably adjusted to 0.5 to 10% by mass, more preferably 1 to 8% by mass, and more It is preferably adjusted to 2 to 5 mass%.

In addition, when a monomer copolymerizable with styrene is used together with styrene as the styrene monomer, the content of the monomer copolymerizable with styrene in the composite resin particles is preferably 10% by mass or less. In this case, the foamability of the composite resin particles can be improved, and the shrinkage of the foamed particles can be prevented. From the viewpoint of making the foamability better, the content of the monomer copolymerizable with styrene in the composite resin particles is more preferably 1 to 8% by mass, and even more preferably 2 to 5% by mass.

The composite resin particle system has an average aspect ratio of 1.30 or less, and its shape is spherical. When the average aspect ratio exceeds 1.30, the bending fracture energy of the foamed composite resin molded body obtained by in-molding the foamed particles obtained by foaming the composite resin particles may be insufficient. From the viewpoint of further improving the bending fracture energy, the average aspect ratio of the composite resin particles is preferably 1.20 or less, and more preferably 1.10 or less. The lower limit of the average aspect ratio of the composite resin particles is preferably 1. The aspect ratio is a value measured by a particle size distribution measuring device or the like, and is a value obtained by dividing the major axis length (largest major diameter) of a particle by the minor axis length (length of the longest portion in a direction perpendicular to the major axis). value. In addition, the term "spherical" includes not only true spheres, but also ellipsoids and other similar spheres.

The 63% volume average particle diameter d63, the 90% volume average particle diameter d90, and the 10% volume average particle diameter d10 of the composite resin particles satisfy the relationship of the following formulas I and II. The left side of Formula II indicates the degree of dispersion Di of the average particle diameter. That is, Di = (d90-d10) / d63. The 63% volume average particle diameter, 90% volume average particle diameter, and 10% volume average particle diameter of the composite resin particles are the cumulative volume values of 63 in the particle size distribution obtained by the laser diffraction / scattering method, respectively. Particle size at%, 90%, and 10%. The particle size distribution and the average aspect ratio are measured using, for example, Millitrac JPA manufactured by Nikkiso Co., Ltd.

When d63 is less than 0.8 mm, the foamability of the composite resin particles may decrease. From the viewpoint of further improving foamability, d63 ≧ 1.0 mm is preferred, and d63 ≧ 1.2 mm is more preferred.

When d63 exceeds 1.6 mm or Di is 0.40 or more, there is a possibility that the bending fracture energy of the foamed composite resin molded body obtained by using the composite resin particles may be insufficient. From the viewpoint of further improving the bending fracture energy, d63 ≦ 1.5 mm is preferred, and d63 ≦ 1.4 mm is more preferred. From the same viewpoint, Di ≦ 0.35 is preferred, and Di ≦ 0.30 is more preferred.

The reason why the average aspect ratio of the composite resin particles is 1.30 or less, d63 is 0.8 to 1.6 mm, and Di is less than 0.40 can increase the bending fracture energy of the obtained foamed composite resin molded body, as follows. In my opinion, if the amount of impregnation of the styrene monomer with the core particles is increased, the impregnation of the styrene monomer with the core particles is likely to become uneven, and the degree of impregnation of the styrene monomer between the particles is liable to vary. In addition, it is considered that when the particle size distribution of the particles is increased, the degree of impregnation of the styrene monomer with the core particles is more likely to vary. As a result, it can be considered that even if the foamed particle molded body obtained from such composite resin particles is sufficiently fused with each other, the mechanical strength of the bent physical properties and the like of each molded body portion varies, and the desired mechanical strength cannot be obtained. In the present invention, by reducing the particle size of the core particles and reducing the particle size distribution, the specific surface area of the core particles is increased. Therefore, it is considered that the impregnation of the styrene-based monomer can be improved and the inter-particles can be suppressed at the same time. The impregnability of the styrene-based monomer is uneven. As a result, it is considered that by making the particle diameter and particle size distribution of the obtained composite resin particles into a specific range, a component derived from a styrene-based monomer does not excessively locally exist near the surface of the composite resin particle, and the component is The composite resin particles are evenly distributed. In addition, in general, if the average particle diameter of the composite resin particles is to be reduced, the average aspect ratio tends to increase. In the present invention, even if the average particle diameter of the composite resin particles is small, the average aspect ratio is small. Therefore, it is considered that when the foamed particles obtained by foaming the composite resin particles are molded in-mold, the filling property of the foamed particles into the mold can be improved. The foamed particle molded body obtained from such composite resin particles is considered to have small variations in mechanical strength such as bending physical properties and high mechanical strength.

CH outer surface of the benzene ring of the polymer surface of the composite resin particles in the infrared spectrum of the styrene monomer contained in the absorption of deformation vibration derived from the absorbance A at a wave number of 698cm ^-1 near _698, and the ethylene-based resin Polymer of styrenic monomer The ratio of absorbance A ₂₈₅₀ derived from the stretching vibration of methylene CH contained in the two is around 2850cm ^-1 , that is, the absorbance ratio A ₆₉₈ / A ₂₈₅₀ , which is a composite resin An index of the component amount of the styrene-based monomer on the surface of the particle. The absorbance of the surface of the composite resin particles is smaller than A ₆₉₈ / A ₂₈₅₀ , which means that the proportion of the components derived from the styrene monomer on the surface of the composite resin particles is small. The absorbance ratio A ₆₉₈ / A _{2850 is} preferably 2 or less. In this case, it is possible to obtain an effect that the fusion of the expanded particles is good and the bending fracture energy of the expanded particle molded body can be increased. From the viewpoint of further improving this effect, the absorbance of the surface of the composite resin particles is more preferably 1.6 or less and further preferably 1.3 or less than A ₆₉₈ / A ₂₈₅₀ . The absorbance ratio A ₆₉₈ / A ₂₈₅₀ on the surface of the composite resin particle is measured by total reflection absorption infrared spectroscopy (ie, ATR method), and is the ratio of the absorbance A ₆₉₈ to the absorbance A ₂₈₅₀ .

The so-called total reflection absorption infrared spectrum analysis is a method that uses infrared light to be totally reflected on the surface of the ATR crystal and is not immersed in the sample, and measures the infrared spectrum of the sample surface to a depth of several μm. Because it can measure the spectrum only by closely connecting the sample to the sample, it is widely used for surface analysis of various substances. However, in the ATR method, as shown in the following formula VI, the refractive index varies with the material of 稜鏡, or the incident angle of infrared light is different, and the immersion depth is also different. Therefore, when measuring non-uniform materials, the measurement needs to be fixed. condition.

The specific measurement method of the absorbance ratio A ₆₉₈ / A ₂₈₅₀ on the surface of the composite resin particles is described below. First, for example, FT / IR-460plus (ATR PRO 450-S type, 稜鏡: diamond, incident angle: 45 °) manufactured by JASCO Corporation is used as a measuring device, and the composite resin particles are brought into close contact with the edges at a pressure of 170 kg / cm ² . The infrared spectrum was measured to obtain an infrared absorption spectrum (without ATR correction). Next, the absorbance A ₆₉₈ and the absorbance A ₂₈₅₀ obtained from the infrared absorption spectrum are measured, and these ratios are obtained, that is, the absorbance ratio A ₆₉₈ / A ₂₈₅₀ . The same measurement was performed for five composite resin particles, and the average of the five was used as the absorbance ratio A ₆₉₈ / A _{2850 of the} composite resin particles.

The coefficient of variation of the absorbance ratio A ₆₉₈ / A ₂₈₅₀ is preferably 0.2 or less. At this time, the uneven fusion occurring in the foamed particle molded body with different parts is small, and the effect of increasing the bending fracture energy of the foamed particle molded body can be obtained. From the viewpoint of further improving this effect, the coefficient of variation of the absorbance is more preferably 0.15 or less than A ₆₉₈ / A ₂₈₅₀ , and even more preferably 0.14 or less.

A ratio of absorbance based absorbance coefficient of variation Cv ₆₉₈ / A ₂₈₅₀ divided by the absorbance value represents the ratio of (average of 5) resulting in A ₆₉₈ / A ₂₈₅₀ standard differential ratio V A ₆₉₈ / A _2850, the system represents the absorbance ratio Indicator of unevenness. In addition, the standard deviation of the absorbance ratio is obtained by the following formula VII: In Formula VII, Ai ₆₉₈ / Ai ₂₈₅₀ represents each measured value of the absorbance ratio, A ₆₉₈ / A ₂₈₅₀ is the average value of the above five absorbance ratios, and Σ indicates that it will be calculated for each measured value (Ai ₆₉₈ / Ai _2850- A ₆₉₈ / A ₂₈₅₀ ) ² all add up. The coefficient of variation Cv is obtained according to the following formula VIII:

[Foamed Particles] The expanded particles are obtained by, for example, foaming the above-mentioned composite resin particles. The foamed particle system is the same as the composite resin particle, and the content ratio of the component derived from the styrene-based monomer to 100 parts by mass of the vinyl resin is more than 400 parts by mass and 1900 parts by mass or less.

The average aspect ratio of the expanded particles is 1.30 or less, and the shape is spherical. When the average aspect ratio of the foamed particles exceeds 1.30, the bending fracture energy of the foamed composite resin molded body may be insufficient. From the viewpoint of further improving the bending fracture energy, the average aspect ratio of the foamed particles is preferably 1.20 or less, and more preferably 1.10 or less.

The apparent density Da of the expanded particles is 20 to 200 kg / m ³ . When the apparent density is less than 20 kg / m ³ , the compressive rigidity of the expanded particle molded body may be lowered. On the other hand, when it exceeds 200 kg / m <^3> , there exists a possibility that the bending fracture energy of a foamed particle molded body may fall. The apparent density Da is preferably 25 to 150 kg / m ³ , and more preferably 30 to 100 kg / m ³ .

The apparent density Da (unit: kg / m ³ ) and 63% volume average particle diameter d63 (unit: mm) of the expanded particles satisfy the relationship of Formula IV:

When (Da / 1000) ^1/3 × d63 <0.8 mm, there is a possibility that the compression rigidity of the foamed composite resin molded article becomes low. From the viewpoint of further improving the compressive rigidity of the foamed composite resin molded body, (Da / 1000) ^1/3 × d63 ≧ 0.9 mm is more preferable, and (Da / 1000) ^1/3 × d63 ≧ 1.0 mm is more preferable.

When (Da / 1000) ^1/3 × d63> 1.6 mm, the bending fracture energy of the foamed composite resin molded article is insufficient, and there is a possibility that fracture may easily occur due to deformation. From the viewpoint of further improving the bending fracture energy, it is better to satisfy (Da / 1000) ^1/3 × d63 ≦ 1.5, and more preferably (Da / 1000) ^1/3 × d63 ≦ 1.4.

In Formula IV, the 1000 series represents the density of the resin, and the Da / 1000 series corresponds to the expansion ratio. (Da / 1000) before foaming the foaming ^1/3 × d63-based particles, i.e. expanded particles was 63% by volume average particle diameter of the non-foamed state approximate equal value. The 63% volume average particle diameter d63 of the foamed particles is a particle diameter at a cumulative volume value of 63% in the particle size distribution obtained by the laser diffraction / scattering method.

The 63% volume average particle diameter d63, 90% volume average particle diameter d90, and 10% volume average particle diameter d10 of the expanded particles satisfy the relationship of the following formula V:

The left side of the formula V indicates the dispersion degree Di of the average particle diameter of the expanded particles. That is, Di = (d90-d10) / d63. The 63% volume average particle diameter, 90% volume average particle diameter, and 10% volume average particle diameter of the foamed particles are the cumulative volume values of 63 in the particle size distribution obtained by the laser diffraction / scattering method, respectively. Particle size at%, 90%, and 10%. The particle size distribution and the average aspect ratio are measured using, for example, Millitrac JPA manufactured by Nikkiso Co., Ltd.

When Di of the foamed particles is 0.5 or more, there is a possibility that the filling properties during foamed particle molding may deteriorate. As a result, the bending fracture energy of the foamed composite resin molded body may be insufficient. From the viewpoint of further improving the bending fracture energy, Di ≦ 0.45 is preferred, and Di ≦ 0.40 is more preferred.

[Production of Composite Resin Particles] The composite resin particles are produced, for example, by performing the following dispersion steps and modification steps. In the dispersion step, the vinyl resin particles are dispersed in an aqueous medium. These vinyl-based resin particles are particles containing a vinyl-based resin as a main component, and are also referred to as core particles in this specification.

In the dispersion step, core particles containing a vinyl resin component as a main component are used, and the core particles may further contain additives such as a bubble regulator, a colorant, a slipper, and a dispersion diameter expanding agent. In addition, the blending amount of the additives can be appropriately adjusted according to the required properties of the expanded particles and the foamed composite resin molded body. The core particles can be produced by blending an additive that is added as needed to the vinyl resin, and melt-kneading the blend, and then granulating.

Melt-kneading can be performed by an extruder. For uniform kneading, it is preferable to mix the ethylene-based resin with each additive component before extrusion. Such mixing can be performed using a mixer such as a Henschel mixer, a spiral belt mixer, a V-type mixer, or a Lodige mixer. The melt-kneading is preferably performed using a single-screw extruder or a twin-screw extruder equipped with a high-dispersion screw such as a Dulmage type, a Maddock type, and a Unimelt type.

The granulation of the core particles is performed, for example, by extruding a melt-kneaded blend by an extruder or the like, and then cutting the extrudate. Granulation can be performed by, for example, a strand cutting method, an underwater cutting method, a thermal cutting method, or the like. From the viewpoint of easy production of composite resin particles, an underwater cutting method is preferred.

The particle weight and L / D of the core particles can be adjusted according to the extrusion amount and the cutter speed when making the core particles. The particle weight of the core particles is preferably 0.4 mg / piece or less. The weight of the particles permeating the core particles is 0.4 mg / piece or less. It is considered that even if the styrene-based monomer impregnates the core particles, the styrene-based monomer is still easily impregnated into the core particles, and it is unlikely to occur between the particles Uneven impregnation. The particle weight is more preferably 0.35 mg / piece or less, and even more preferably 0.3 mg / piece or less. When the particle weight of the core particles is too small, coagulation tends to occur during polymerization. The particle weight is preferably 0.01 mg / piece or more, more preferably 0.03 mg / piece or more, and even more preferably 0.05 mg / piece or more.

The L / D of the core particles is preferably 1 to 3. When the L / D of the core particles is less than 1 or more than 3, the composite resin particles obtained by impregnating the polymerized styrene monomer or the foamed particles obtained by foaming the composite resin particles are flat and have an increased aspect ratio. Yu. As a result, there is a possibility that the filling property at the time of molding the composite resin expanded particles may deteriorate. From the viewpoint of further improving the filling property, the L / D of the core particles is more preferably from 1 to 2.5, and even more preferably from 1 to 2. In addition, D represents the diameter of the cutting surface of the nuclear particle, and L represents the length in the direction perpendicular to the cutting surface of the nuclear particle.

The preferred manufacturing conditions when using the underwater cutting method as the granulation method are described below. In the underwater cutting method, the vinyl resin is melt-kneaded by an extruder, and the molten resin is extruded into a water stream through a small hole of a mold provided at the front end of the extruder. It is then cut off in the water stream and made into nuclear particles.

In order to obtain core particles having a particle weight of 0.4 mg / piece or less and an L / D of 1 to 3, it is preferable to use a mold having holes having a diameter of 0.6 mm or less so that the shear rate per hole during extrusion is 3 The discharge amount of × 10 ³ to 1 × 10 ⁴ (1 / s), the molten resin is extruded at a resin temperature of 60 to 300 Pa · s at a melt viscosity of the molten resin at a shear rate during extrusion. The resin temperature referred to here is a temperature obtained by measuring the temperature of the center portion of the resin flow path between the extruder and the mold with a thermocouple thermometer.

The melt viscosity of the vinyl resin at the shear rate during extrusion is preferably adjusted to 60 to 300 Pa · s, more preferably 80 to 250 Pa · s, and even more preferably 100 to 200 Pa · s. In addition, the temperature range of the melt viscosity can be measured using a measuring machine such as CAPILOGRAPH 1D manufactured by Toyo Seiki Seisakusho Co., Ltd. using a nozzle having a nozzle diameter of 1.0 mm and a nozzle length of 10 mm. Specifically, first, at a melting temperature of 150 ° C and a measurement temperature of an ethylene-based resin raw material (raw material PE) used for the production of nuclear particles, a shear rate of 1 × 10 ² to 1 × 10 ⁵ (1 / s ) Range, the melt viscosity of the raw material PE (hereinafter simply referred to as the melt viscosity of the raw material) is measured (first measurement). Next, the measurement temperature was lowered by only 5 ° C from the measurement temperature of the first measurement, and the melt viscosity of the raw material was measured in the same manner (second measurement). Furthermore, the measurement temperature was lowered by only 5 ° C from the measurement temperature of the second measurement, and the melt viscosity of the raw material was measured in the same manner. This operation is repeated until the vinyl resin cannot flow. Then, in a semi-logarithmic chart in which the vertical axis is logarithmic, the vertical axis is the melt viscosity (Pa · s) of the shearing speed at the time of extrusion, and the horizontal axis is the measurement temperature. The temperature at which the melt viscosity of the raw material was in the range of 60 to 300 Pa · s was obtained by interpolation.

When the melting temperature of the raw material PE is set to Tm, the resin temperature of the molten resin is preferably Tm + 65 ° C to Tm + 115 ° C, more preferably Tm + 70 ° C to Tm + 115 ° C, and even more preferably Tm + 75 ° C. ~ Tm + 110 ° C.

The diameter of the die hole is preferably 0.6 mm or less, preferably 055 mm or less, and more preferably 0.5 mm or less. If the diameter of the die hole is too small, the die hole is liable to be blocked in the production of nuclear particles. Therefore, the diameter of the die hole is preferably 0.3 mm or more, more preferably 0.35 mm or more, and still more preferably 0.4 mm or more.

The shear rate per die hole at the time of extrusion is preferably set to 3 × 10 ³ to 1 × 10 ⁴ (1 / s). In addition, the shear rate γ of each die hole can be calculated by the following formula assuming that the melt is a Newtonian fluid; γ = 4 × Q / (π × R3) Here, Q represents each die hole The resin flow rate [m ³ / s], R represents the radius [m] of the die hole.

In order to reduce the generation of fine particles composed of nuclear particles with an excessively small particle size, or aggregate particles formed by fusion of the nuclear particles with each other, it is preferable to set the discharge amount of the molten resin per unit cross-sectional area of the die hole outlet to 0.4 to 2 kg. / h ・ mm ² . Similarly, it is preferable that the discharge amount of the molten resin per one die hole is set to 0.05 to 0.3 kg / h.

The extrudate is cut in a cutting chamber filled with circulating water to form core particles. The temperature of the water flow in the cutting chamber filled with circulating water is preferably from 50 to 80 ° C from the viewpoint of preventing poor cutting or clogging of mold holes. It is more preferably 50 to 75 ° C, and still more preferably 60 to 70 ° C.

The ethylene-based resin preferably contains an antioxidant. In this case, gelation of the vinyl-based resin can be prevented at the time of extrusion, and die holes are not easily blocked. Examples of the antioxidant include a phenol-based antioxidant, a sulfur-based antioxidant, and a phosphorus-based antioxidant. The amount of the antioxidant to be added is preferably 0.01 to 1 part by mass based on 100 parts by mass of the vinyl resin. It is more preferably 0.02 to 0.5 parts by mass, and even more preferably 0.05 to 0.2 parts by mass.

The vinyl resin preferably contains a metal soap. In this case, the cutting property of the molten resin is more favorable when the extrudate is cut.

As the metal soap, zinc 12-hydroxystearate, calcium 12-hydroxystearate, magnesium 12-hydroxystearate, aluminum 12-hydroxystearate, barium 12-hydroxystearate, 12-hydroxystearate can be used. 12-hydroxystearate soaps such as lithium stearate, 12-hydroxystearate sodium; zinc stearate, calcium stearate, magnesium stearate, aluminum stearate, barium stearate, lithium stearate, Stearic acid soaps such as sodium stearate; zinc behenate, calcium behenate, magnesium behenate, lithium behenate, sodium behenate, etc. Octadecanoic acid soaps such as zinc, calcium octaate, magnesium octaate, aluminum octaate, lithium octaate, and sodium octadecate; zinc laurate, calcium laurate, barium laurate Lauric acid soaps such as lithium laurate and sodium laurate. As the metal soap, 12-hydroxystearate is preferably used, and zinc 12-hydroxystearate is more preferably used. The amount of the metal soap added is preferably 0.01 to 2 parts by mass, more preferably 0.05 to 1 part by mass, and still more preferably 0.1 to 0.5 part by mass based on 100 parts by mass of the vinyl-based resin.

Based on the viewpoint that it is easy to obtain composite resin particles having relatively small aspect ratios and that the foamability of the composite resin particles can be further improved, the melt mass flow rate of core particles (that is, MFR: temperature 190 ° C, load 2.16kg) is preferably 1 to 12g / 10 minutes. It is more preferably 1 to 10 g / 10 minutes, and even more preferably 1 to 5 g / 10 minutes. The MFR of the vinyl resin under the conditions of a temperature of 190 ° C and a load of 2.16 kg is a value measured based on JIS K7210-1: 2014. In addition, as the measuring device, MELT INDEXER (for example, L203, manufactured by Po Industrial Co., Ltd.) can be used.

In the dispersing step, a dispersion liquid in which the core particles are dispersed in an aqueous medium can be obtained. As the aqueous medium, for example, deionized water can be used. The core particles are preferably dispersed in an aqueous medium together with a suspending agent or a surfactant. In this case, the styrene-based monomer can be uniformly suspended in the aqueous medium. As the suspending agent, for example, tricalcium phosphate, hydroxide apatite, magnesium pyrophosphate, magnesium phosphate, aluminum hydroxide, iron hydroxide, titanium hydroxide, magnesium hydroxide, barium phosphate, calcium carbonate, magnesium carbonate, carbonic acid can be used. Barium, calcium sulfate, barium sulfate, talc, kaolin, bentonite and other particulate inorganic suspending agents. In addition, organic suspension agents such as polyvinylpyrrolidone, polyvinyl alcohol, ethyl cellulose, and hydroxypropyl methyl cellulose can also be used. Among these, tricalcium phosphate, hydroxide apatite, and magnesium pyrophosphate are preferred. These suspending agents can be used alone or in combination of two or more.

The 50% volume average particle diameter of the suspending agent is preferably 1 to 6 μm. In this case, the styrene-based monomer can be stably suspended, and generation of a resin mass can be prevented. As a result, the particle size distribution of the composite resin particles obtained after the modification step can be reduced, and the dispersion degree of the average particle diameter of the composite resin particles can be reduced. From the viewpoint of further reducing the degree of dispersion, the 50% volume average particle diameter of the suspending agent is more preferably 2 to 5 μm.

The 50% volume average particle diameter of the suspending agent is the particle diameter when the suspending agent is dispersed in water, and the particle size distribution is measured by laser diffraction scattering method, and the cumulative volume of the total particle volume reaches 50%. The measurement of the particle size distribution by the laser diffraction scattering method uses, for example, Microtrac MT-3300EX manufactured by Nikkiso Co., Ltd. The shape factor of particles is considered non-spherical.

When the amount of the suspending agent is too small, it is difficult to stably suspend the styrene-based monomer in the modification step, and there is a possibility that a resinous mass may be generated. On the other hand, when the amount of the suspending agent is too large, not only the manufacturing cost increases, but also the particle size distribution of the composite resin particles obtained after the modification step may be widened. Therefore, the amount of the suspending agent is preferably 0.05 to 10 mass ppm based on the solid content relative to 100 parts by mass of the aqueous medium of the suspension polymerization system (specifically, all water in an aqueous system such as a slurry containing a reaction product). , More preferably 0.3 to 5 mass ppm.

A surfactant can be added to the aqueous medium. As the surfactant, for example, an anionic surfactant, a nonionic surfactant, a cationic surfactant, an amphoteric surfactant, or the like can be used. These surfactants can be used alone or in combination.

As the anionic surfactant, for example, sodium alkylsulfonate, sodium alkylbenzenesulfonate, sodium lauryl sulfate, sodium α-olefin sulfonate, sodium dodecyl diphenyl ether disulfonate, and the like can be used. As the non-ionic surfactant, for example, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, and the like can be used.

As the cationic surfactant, alkylamine salts such as coconut alkylamine acetate and stearylamine acetate can be used. In addition, quaternary ammonium such as lauryltrimethylammonium chloride and stearyltrimethylammonium chloride can also be used. As an amphoteric surfactant, alkyl betaines such as lauryl betaine and stearyl betaine can be used. Alternatively, an alkylamine oxide such as lauryldimethylamine oxide may be used.

As the surfactant, an anionic surfactant is preferably used. More preferably, it is an alkali metal salt of an alkylsulfonic acid having 8 to 20 carbon atoms. Thereby, the suspension can be sufficiently stabilized. More preferably, it is a sodium salt.

In the dispersing step, in the dispersing step, 100 to 500 mass ppm of a surfactant is preferably added to the aqueous medium. In this case, the styrene-based monomer can be more stably suspended, the generation of resin mass can be further prevented, and the particle size distribution of the composite resin particles can be further reduced. From the viewpoint of further preventing the generation of resin lumps and further reducing the particle size distribution, the addition amount of the surfactant is more preferably 130 to 350 ppm by mass. It is more preferable to add 150 to 300 mass ppm.

In an aqueous medium, an electrolyte composed of inorganic salts such as lithium chloride, potassium chloride, sodium chloride, sodium sulfate, sodium nitrate, sodium carbonate, sodium bicarbonate and the like can be added as required. Further, in order to obtain a foamed composite resin molded article having more excellent toughness and mechanical strength, it is preferable to add a water-soluble polymerization inhibitor to an aqueous medium. As the water-soluble polymerization inhibitor, for example, sodium nitrite, potassium nitrite, ammonium nitrite, L-ascorbic acid, citric acid, and the like can be used.

The water-soluble polymerization inhibitor is not easily impregnated in the core particles and is soluble in an aqueous medium. Therefore, although the polymerization of the styrene-based monomer impregnated with the core particles can proceed, it is possible to suppress fine droplets of the styrene-based monomer not impregnated in the aqueous medium of the core particles, and the core particles continuously absorbed by the core particles. Polymerization of styrenic monomer near the surface. As a result, it was estimated that the amount of the styrene resin on the surface of the composite resin particles can be reduced, and the toughness of the obtained foamed composite resin molded body can be improved. The amount of the water-soluble polymerization inhibitor to be added is 100 parts by mass with respect to an aqueous medium (refers to all water in an aqueous system such as a slurry containing a reaction product), preferably 0.001 to 0.1 parts by mass, and more preferably 0.005. ～ 0.06 parts by mass is preferable.

In the modification step, the core particles are impregnated with the styrene-based monomer in an aqueous medium and polymerized. The polymerization of the styrene-based monomer is performed in the presence of a polymerization initiator. In this case, graft polymerization of the styrene-based monomer to the vinyl resin may occur simultaneously with the polymerization of the styrene-based monomer, and further crosslinking of the ethylene-based resin may occur. A polymerization initiator is used in the polymerization of the styrene-based monomer. However, a crosslinking agent may be used in combination to crosslink the vinyl resin, if necessary. When a polymerization initiator and / or a crosslinking agent is used, it is preferable to dissolve the polymerization initiator and / or the crosslinking agent in a styrene-based monomer in advance. In the modification step, a styrene-based monomer impregnated with core particles containing a vinyl-based resin can be polymerized. Therefore, in addition to the ethylene-based resin, composite resin particles containing a styrene-based resin component and a vinyl-based resin component generated by polymerization can be obtained.

As the polymerization initiator, a suspension polymerization method for use in a styrene-based monomer can be used. For example, a polymerization initiator that is soluble in a styrene-based monomer and has a 10-hour half-life temperature of 50 to 120 ° C can be used. As the polymerization initiator, for example, cumene hydroperoxide, dicumene peroxide, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxybenzene can be used. Formates, benzamidine peroxide, tertiary butyl peroxy isopropyl carbonate, tertiary butyl peroxy-2-ethylhexyl carbonate, tertiary pentyl peroxy-2-ethylhexyl Organic peroxides, such as carbonate, hexylperoxy-2-ethylhexyl carbonate, and lauryl fluorene. Moreover, as a polymerization initiator, azo compounds, such as azobisisobutyronitrile, etc. can also be used. These polymerization initiators may be used singly or in combination of two or more kinds. Furthermore, from the viewpoint of easily reducing the residual styrene-based monomer, tertiary butylperoxy-2-ethylhexanoate is preferred. The polymerization initiator is preferably used in an amount of 0.01 to 3 parts by mass based on 100 parts by mass of the styrene-based monomer.

Further, as the cross-linking agent, a substance that does not decompose at the polymerization temperature and decomposes at the cross-linking temperature at a 10-hour half-life temperature that is 5 ° C to 50 ° C higher than the polymerization temperature is preferably used. Specifically, peroxides such as dicumyl peroxide, 2,5-tert-butylperoxybenzoate, and 1,1-bis-tert-butylperoxycyclohexane can be used. The crosslinking agent can be used alone or in combination of two or more. The blending amount of the crosslinking agent is preferably 0.1 to 5 parts by mass based on 100 parts by mass of the styrene-based monomer.

In the modification step, when the styrene-based monomer is impregnated with the core particles and polymerized, the total amount of the styrene-based monomer to be blended may be integrally added to the aqueous medium in which the core particles are dispersed, but it may be The total amount of the styrene-based monomer to be blended is divided into, for example, 2 or more parts, and these monomers are added at different time points. Specifically, a part of the total amount of the styrene-based monomer to be blended may be added to the aqueous medium in which the core particles are dispersed to impregnate and polymerize the styrene-based monomer. Second, the benzene to be blended may be further blended. The remainder of the vinyl-based monomer is added to the aqueous medium in one or two or more portions. By adding the styrene-based monomer separately as in the latter case, it is possible to further suppress the aggregation of the resin particles during polymerization.

When the styrene-based monomer is added separately, it is preferred that at least the polymerization initiator is previously dissolved in the styrene-based monomer (hereinafter referred to as the "first monomer") added first. Preferably, more than 75% of the total amount of the polymerization initiator to be blended is dissolved in the first monomer, and more preferably, more than 80% is dissolved in advance. At this time, during the production of the composite resin particles, the styrene-based monomer can be sufficiently impregnated with the vinyl-based resin, and the suspension system can be prevented from being unstable during polymerization. As a result, it is possible to obtain a foamed composite resin molded body having a higher level of both excellent rigidity of a styrene resin and excellent adhesive strength of a vinyl resin.

When a part of the styrene-based monomer to be blended is added as the first monomer as described above, the remaining part of the total amount of the styrene-based monomer to be blended may be used as the second monomer in the first After the monomer was added, it was added at a different time from the first monomer. The second monomer may be further divided and added.

The permeability ratio (mass ratio of the first monomer to the core particles) of the styrene-based monomer (first monomer) is preferably 0.5 or more. In this case, it is easy to make the shape of the composite resin particles closer to a spherical shape. From the same viewpoint, the penetration ratio is more preferably 0.7 or more, and even more preferably 0.8 or more.

The penetration is preferably 1.5 or less. In this case, it is possible to further prevent the styrene-based monomer from being polymerized before the core particles are sufficiently impregnated, and it is possible to further prevent the generation of the resin mass. From the same viewpoint, the penetration ratio of the first monomer is more preferably 1.3 or less, and even more preferably 1.2 or less.

In the modification step, when the melting point of the ethylene-based resin in the core particles is set to Tm (° C) and the polymerization temperature in the modification step is set to Tp (° C), Tm-Tp is preferably -10 to 30 (° C ). In this case, the styrene-based monomer can be sufficiently impregnated in the production of the composite resin particles to prevent the suspension system from becoming unstable during polymerization. As a result, it is possible to obtain a foamed composite resin molded body having a higher level of both excellent rigidity of a styrene resin and excellent adhesion of a vinyl resin.

The impregnation temperature and polymerization temperature in the modification step vary depending on the type of the polymerization initiator used, but it is preferably 60 to 105 ° C, and more preferably 70 to 105 ° C. The crosslinking temperature varies depending on the type of the crosslinking agent used, but it is preferably 100 to 150 ° C. The impregnation temperature of the styrene-based monomer is a temperature at which the styrene-based monomer is impregnated into the vinyl-based resin. The polymerization temperature is a temperature at which a styrene-based monomer impregnated with a vinyl-based resin is polymerized.

A bubble regulator may be added to the styrene-based monomer. As the bubble regulator, for example, aliphatic monoammonium, fatty acid diammonium, polyethylene wax, methylenebisstearic acid, and the like can be used. Examples of the aliphatic monoammonium include ammonium oleate and ammonium stearate. As the fatty acid bisamide, for example, ethylene bisstearate can be used. The bubble regulator is preferably used in an amount of 0.01 to 2 parts by mass based on 100 parts by mass of the styrene-based monomer. Moreover, a plasticizer, an oil-soluble polymerization inhibitor, a flame retardant, a colorant, a chain transfer agent, etc. may be added to the styrene-based monomer as required.

As the plasticizer, for example, fatty acid esters, acetylated monoglycerides, fats and oils, and hydrocarbon compounds can be used. As the fatty acid ester, for example, glycerin tristearate, glycerin tricaprylate, glycerin trilaurate, sorbitan tristearate, sorbitan monostearate, and butylstearate can be used. Esters, etc. In addition, as the acetylated monoglyceride, for example, glycerol diethylfluorene monolaurate can be used. Examples of fats and oils include hardened tallow and hardened castor oil. As the hydrocarbon compound, for example, cyclohexane, flowing paraffin, or the like can be used. As the oil-soluble polymerization inhibitor, for example, p-tert-butylcatechol, hydroquinone, benzoquinone, and the like can be used. As the flame retardant, for example, hexabromocyclododecane, tetrabromobisphenol A-based compound, trimethyl phosphate, brominated butadiene-styrene block copolymer, aluminum hydroxide, and the like can be used. As the colorant, furnace black, channel black, thermal carbon black, acetylene black, Ketjen black, graphite, carbon fiber, and the like can be used. As the chain transfer agent, for example, n-dodecyl mercaptan or α-methylstyrene dimer can be used. These additives may be added alone or in combination of two or more.

The above-mentioned additives such as a bubble regulator, a plasticizer, an oil-soluble polymerization inhibitor, a flame retardant, a colorant, and a chain transfer agent may be dissolved in a solvent and then impregnated into the core particles. As the solvent, for example, aromatic hydrocarbons such as ethylbenzene and toluene, and aliphatic hydrocarbons such as heptane and octane can be used.

[Production of Foamed Particles] Foamed particles are obtained, for example, by foaming the above-mentioned composite resin particles. For the foaming of the composite resin particles, a conventionally known foaming method can be applied. Specifically, for example, a composite resin particle and a foaming agent may be dispersed in a dispersion medium such as water in a pressure-resistant container, and the resin particles may be softened by heating and the foaming agent may be impregnated in the composite resin particles. A method of releasing composite resin particles from a container at a temperature equal to or higher than the softening temperature of the resin particles under a low pressure (for example, usually at atmospheric pressure) and foaming them (hereinafter also referred to as a direct foaming method). Further, for example, a method of taking out a foamable composite resin particle containing a foaming agent from a closed container, and heating the foamable composite resin particle with a heating medium such as steam to make it foam can be employed.

Among these methods, a direct foaming method is preferably used. In addition, the temperature in the container (that is, the foaming temperature) when the foamable composite resin particles impregnated with the foaming agent are discharged from the pressure-resistant container, are based on the apparent density of the target foamed particles and the base resin. The composition, the type of foaming agent, the blending amount, and the like are determined. The foaming temperature may be approximately equal to or higher than the glass transition temperature (Tg) of the styrene-based resin component polymerized by the styrene-based monomer that is one of the components of the composite resin particle, and the decomposition of the resin component constituting the composite resin particle is initiated Within the temperature range.

[Foamed composite resin molded article] The foamed composite resin molded article can be produced by a known in-mold molding method using steam heating. That is, a foamed composite resin molded body can be obtained by filling a plurality of foamed particles into a molding die such as a mold and introducing steam into the molding die to fuse the foamed particles with each other. [Example]

(Example 1) A method for producing the composite resin particles of the example will be described. In this example, foamed composite resin particles are produced to produce foamed particles, and a plurality of foamed particles are molded in-mold to produce a foamed composite resin molded body.

(1) Production of core particles: 100 parts by mass of a linear low-density polyethylene resin (TOSOH (trade name), Nipolon Z HF210K), which is a vinyl-based resin, will be used as a foaming core agent of zinc borate ( Tomita Pharmaceutical Co., Ltd., zinc borate 2335) 1.44 parts by mass and master batch of antioxidant ("TMB113" manufactured by Toho Corporation, PE: 90% by mass, phosphorus-based stabilizer: 6.5% by mass, hindered phenol Antioxidant: 3.5% by mass) was put into a Henschel mixer (Mitsui Miike Chemical Machinery Co., Ltd .; type: FM-75E), and a resin mixture was obtained by mixing for 5 minutes. PE refers to polyethylene.

Next, as shown in FIG. 1, the pelletized resin mixture 10 is placed in a cylinder 20 of an extruder 2 (manufactured by Toshiba Machinery Co., Ltd., type: TEM-26SS; a twin-screw extruder with a nominal diameter of φ 26 mm). The inside is melt-kneaded. Thereafter, the molten kneaded material of the resin is extruded from the mold 21 into the cutting chamber 22 filled with the circulating water 221, and cut by a cutter 23 provided in the cutting chamber 22. The cutter 23 is disposed to face the discharge port of the mold 21. That is, the discharge toward the cutting chamber 22 is cut by an underwater cutting method to obtain vinyl-based resin particles 1 (that is, core particles 1). The nuclear particles 1 are separated and recovered from the circulating water 221 by the centrifugal separator 24. In this way, the core particles 1 having a substantially cylindrical shape as illustrated in FIG. 2 are obtained.

The resin temperature at the time of extrusion from the mold 21 was 200 ° C, and the temperature of the mold was 350 ° C. The die hole diameter of the mold 21 was 0.45 mm, and the number of die holes was 90. The discharge amount into the cutting chamber was 18 kg, the discharge amount per unit area of the die hole was 1.26 kg / h · mm ² , and the discharge amount per die hole was 0.2 kg / h. The cutter 23 has 10 blades and rotates at a number of revolutions of 1800 rpm.

The core particles 1 prepared as described above were measured for weight, L / D, and MFR. The results are shown in Table 1. The measurement method is as follows.

<Weight of Nuclear Particles> (1) The weight of 20 nuclear particles was weighed to calculate the weight per nuclear particle. This operation was performed 5 times, and the arithmetic average of the measured values of 5 times was used as the weight (unit: mg / piece) of the nuclear particles.

<L / D of nuclear particle> (1) The nuclear particle was photographed with a microscope manufactured by KEYENCE Corporation VHX-100F (lens: VH-Z25, magnification: 25 times). The diameter D of the cut surface and the length L in a direction perpendicular to the cut surface were measured from the photographed nuclear particles (see FIG. 2). This operation was performed on 20 nuclear particles, and the arithmetic average of 20 measured values was used as the L / D of the nuclear particles.

<MFR of nuclear particles> Based on JIS K7210-1: 2014, the MFR of nuclear particles was measured by MELT INDEXER (type L203 manufactured by Takara Industry Co., Ltd.). The measurement was performed under the conditions of a temperature of 190 ° C and a load of 2.16 kg.

(2) Preparation of composite resin particles Into an autoclave with a volume of 3L and equipped with a stirring device, 1000 g of deionized water was added, and 6.0 g of sodium pyrophosphate was further added. Then, 12.9 g of powdery magnesium nitrate hexahydrate was added, and it stirred at 40 degreeC for 30 minutes. Thereby, a magnesium pyrophosphate slurry is prepared as a suspending agent. The 50% volume average particle diameter of the suspending agent was 4.1 μm. Next, to this suspending agent, 2.0 g of sodium laurylsulfonate as a surfactant, 0.21 g of sodium nitrite as a water-soluble polymerization inhibitor, and 75 g of core particles were charged. As a sodium lauryl sulfonate system, a 10% by mass aqueous solution was used.

Next, as the polymerization initiator, tertiary butyl peroxy-2-ethylhexyl monocarbonate ("PERBUTYL E" manufactured by Nippon Oil Co., Ltd.) and tertiary hexyl peroxybenzoate (manufactured by Nippon Oil Co., Ltd.) were prepared. "PERHEXYL Z"). As a chain transfer agent, α-methylstyrene dimer ("Nofmer MSD" manufactured by Nippon Oil Co., Ltd.) was prepared. Then, 1.67 g of tertiary butyl peroxy-2-ethylhexyl monocarbonate, 0.835 g of tertiary hexyl peroxybenzoate, and 0.665 g of α-methylstyrene dimer were dissolved in the first monomer. (That is, styrene-based monomer). Then, while stirring the inside of the autoclave at a rotation speed of 500 rpm, the dissolved matter was put into the above-mentioned autoclave into which the nucleated particles and the like were put. As the first monomer, a mixed monomer of 60 g of styrene and 15 g of butyl acrylate was used.

Next, after the air in the autoclave was replaced with nitrogen, the temperature was increased, and the temperature in the autoclave was increased to 100 ° C. for 1 hour and 30 minutes. After the temperature was raised, the temperature was maintained at 100 ° C for 1 hour. Thereafter, the stirring speed was reduced to 450 rpm, and the temperature was maintained at 100 ° C for 7.5 hours. In addition, when 1 hour passed after the temperature reached 100 ° C, 350 g of styrene as a second monomer (that is, a styrene-based monomer) was added to the autoclave over 5 hours.

Next, the inside of the autoclave was heated to a temperature of 125 ° C. over 2 hours, and kept at 125 ° C. for 5 hours directly. Thereafter, the inside of the autoclave was cooled, and the contents (specifically, composite resin particles) were taken out. Next, nitric acid was added to dissolve magnesium pyrophosphate adhering to the surface of the composite resin particles. Thereafter, dewatering and washing were performed with a centrifugal separator, and moisture attached to the surface was removed with an air-flow drying device to obtain spherical composite resin particles.

Table 3 shows the content ratio of the ethylene-based resin (PE) and the content ratio of the component (St) derived from the styrene-based monomer in the composite resin particles produced as described above. In addition, the degree of dispersion of the 10% by volume average particle diameter d10, the 63% by volume average particle diameter d63, and the 90% by volume average particle diameter d90 and 63% by volume average particle diameter were measured for the composite resin particles (i.e., (d90-d10) / d63 ), The average aspect ratio, the coefficient of variation of the surface absorbance ratio A ₆₉₈ / A ₂₈₅₀ , and the absorbance ratio A ₆₉₈ / A ₂₈₅₀ . The results are shown in Table 3. The measurement method is as follows.

<Average particle diameter, dispersion degree, and average aspect ratio> The particle size distribution measuring device "Millitrac JPA" of Nikkiso Co., Ltd. was used to measure the particle size distribution of composite resin particles and observe the particle shape. Specifically, first, 30 g of the composite resin particles were dropped freely from a sample supply feeder of a measurement device, and a projection image was captured by a CCD camera. Secondly, the captured image information is sequentially calculated and joined to determine the conditions of the image analysis method that outputs the particle size distribution and shape index results. Thereby, each particle diameter (d10, d63, d90) mm and average aspect ratio at the cumulative volume value of 10%, 63%, and 90% in a particle size distribution were calculated. From this equivalent value, the dispersion of 63% average particle diameter was calculated by the following formula. The average particle diameter and average aspect ratio are values measured for the composite resin particle group immediately after production, and are values obtained for the composite resin particle group that has not been classified by screening or the like. The average aspect ratio is an arithmetic average value based on data of 1,000 particles. Dispersion of 63% volume average particle size = (d90-d10) / d63

<Absorbance ratio A ₆₉₈ / A ₂₈₅₀ and its coefficient of variation> As a measuring device, FT / IR-460plus (ATR PRO 450-S type, 入射: diamond, incident angle: 45 °) manufactured by JASCO Corporation was used as a measuring device, and composite resin particles were used. The pressure was 170 kg / cm ^{2 and} the osmium was in close contact with each other, and the infrared spectrum was measured to obtain an infrared absorption spectrum (without ATR correction). Next, the absorbance A ₆₉₈ at a wave number of ₆₉₈ cm ^-1 and the absorbance A ₂₈₅₀ at a wave number of 2850 cm ^-1 obtained from the infrared absorption spectrum were measured, and these ratios were obtained, that is, the absorbance ratio A ₆₉₈ / A ₂₈₅₀ . The same measurement was performed for five composite resin particles, and the average of the five was used as the absorbance ratio A ₆₉₈ / A _{2850 of the} composite resin particles. The coefficient of variation Cv of the absorbance ratio A ₆₉₈ / A ₂₈₅₀ is calculated according to the above formula VII.

(3) Production of foamed particles 500500 g of composite resin particles and 3500 g of water as a dispersion medium were fed into a 5 L pressure-resistant closed container equipped with a stirrer. Next, 5 g of kaolin as a dispersant and 0.5 g of sodium alkylbenzenesulfonate as a surfactant were further added to the dispersion medium in the pressure-resistant closed container. Next, the inside of the pressure-resistant closed container was stirred at a rotation speed of 300 rpm, and the inside of the container was heated to a foaming temperature of 165 ° C.

Thereafter, carbon dioxide of the inorganic physical blowing agent was pressed into the pressure-resistant closed container so that the pressure in the pressure-resistant closed container reached 4 MPa (G: gauge pressure), and maintained at the same temperature (ie, 165 ° C). 15 minutes. As a result, carbon dioxide is impregnated into the composite resin particles to obtain foamable composite resin particles.

Next, the foamable composite resin particles and the dispersion medium were released together from a closed container to atmospheric pressure to obtain spherical foamed particles having an apparent density of 80 kg / m ³ . Since the foamed particles are foams of composite resin particles, they can also be referred to as composite resin foamed particles.

The dispersions of the 10% volume average particle diameter d10, 63% volume average particle diameter d63, and 90% volume average particle diameter d90, 63% volume average particle diameter of the foamed particles produced as described above were measured (i.e. (d90-d10 ) / d63), average aspect ratio, surface absorbance ratio A ₆₉₈ / A ₂₈₅₀ , apparent density. In addition, a value of (apparent density / 1000) ^1/3 × d63 was calculated. The results are shown in Table 3. The measurement method is as follows.

<Average particle diameter, dispersion degree, and average aspect ratio> Measured and calculated in the same manner as each volume average particle diameter, dispersion degree, and average aspect ratio of the composite resin particles, except that the foamed particles are used instead of the composite resin particles.

<Absorbance ratio A ₆₉₈ / A ₂₈₅₀ > Measurement was performed in the same manner as the absorbance ratio A ₆₉₈ / A _{2850 of the} composite resin particles except that the foamed particles were used instead of the composite resin particles.

<Apparent density> First, the group of expanded particles dried at a temperature of 23 ° C for 24 hours is sunk into water at 23 ° C, and the apparent volume of the expanded particles is determined from the amount of water level rise. The apparent density (unit: kg / m ³ ) of the expanded particles was obtained by dividing the mass of the expanded particle group by the apparent volume and then converting the unit.

(4) Production of a foamed composite resin molded body Next, a foamed composite resin molded body is produced by in-mold molding of foamed particles. The expanded particles are filled in a mold having a flat plate-shaped molding cavity having a length of 250 mm, a width of 200 mm, and a thickness of 10 mm or 50 mm. Next, by introducing water vapor into the mold, the foamed particles are heated and fused to each other. After that, the inside of the mold was cooled by water cooling, and then the formed body was taken out of the mold. Further, the formed body was allowed to stand in an oven adjusted to a temperature of 60 ° C. for 12 hours to dry and mature the formed body. In this manner, a molded body in which a plurality of foamed particles are fused to each other is obtained. In addition, since a foamed composite resin molded body is formed by molding foamed particles, it can also be referred to as a foamed particle molded body.

The formed article produced as described above was measured for filling properties, apparent density, fusion rate, flexural modulus, breaking energy, and compressive strength. The filling property was evaluated by using a molded body having a length of 250 mm, a width of 200 mm, and a thickness of 10 mm. For the measurement of apparent density, fusion rate, flexural modulus of elasticity, breaking energy, and compressive strength, a molded body having a length of 250 mm, a width of 200 mm, and a thickness of 50 mm was used. The results are shown in Table 3. The evaluation method and measurement method are as follows.

<Fillability> 成形 The molded article was visually confirmed and rated as "○" when no filling failure occurred, and "△" when some filling failure occurred, and "×" when the molding failure could not be obtained.

<Apparent density> ＞ The apparent density is calculated by dividing the mass of the formed body by the volume obtained from the external dimensions.

<Fusion rate> 成形 Bend the molded body and break it into approximately equal parts. Observe the fracture surface, and measure the number of foamed particles with internal fracture and the number of foamed particles with peeling at the interface. Next, calculate the ratio of the total number of foamed particles with internal cracks to the total number of foamed particles with internal cracks and foamed particles with peeling at the interface, express it as a percentage, and use this value as the fusion rate ( %).

<Bending elastic modulus, bending fracture energy, and coefficient of variation> The bending elastic modulus is measured according to the three-point bending test method described in JIS K7221-1: 2006. Specifically, five test pieces having a thickness of 20 mm × width 25 mm × length 120 mm were cut out from randomly selected portions of the molded body so that the entire surface was a cutting surface. After placing the test piece in a constant temperature and humidity room at 23 ° C and 50% humidity for 24 hours, the distance between the fulcrum points is 100mm, the radius of the indenter is R15.0mm, the radius of the support table is R15.0mm, the test speed is 20mm / min, Under conditions of a room temperature of 23 ° C and a humidity of 50%, the flexural modulus was measured using an Autograph AGS-10kNG tester manufactured by Shimadzu Corporation. The arithmetic mean of the measured values at 5 points is used as the measurement result of the bending elastic modulus.

The relationship between the deflection (unit: mm) and load (unit: kN) in the load / deflection curve obtained during the measurement of the bending elastic modulus was calculated from the arithmetic mean of the five measured values up to the breaking point. Energy (unit: MJ / m ³ ). In addition, the bending fracture energy is calculated by converting the load (kN) into stress (MPa) from the area enclosed by the stress curve up to the breaking point and the horizontal axis (that is, the deflection amount). The coefficient of variation of the bending fracture energy is calculated by dividing the standard deviation by the arithmetic mean of 5 points in the same manner as the coefficient of variation of the absorbance ratio.

<Compressive strength> 50 A rectangular parallelepiped test piece having a length of 50 mm, a width of 50 mm, and a thickness of 25 mm was cut out from the central portion of the foamed composite resin molded body. Next, for this test piece, the compressive load at 50% strain was obtained in accordance with JIS K6767-1999. The compressive load was divided by the compressive area of the test piece to calculate the compressive strength (that is, 50% compressive stress).

(Example 2) In the production of nuclear particles, in addition to the discharge volume: 15 kg, the discharge volume per unit area of the mold hole: 1.05 kg / h · mm ² , the discharge volume per one mold hole: 0.17 kg / h Extrusion was performed under the same conditions, and cutting was performed under the condition of the number of cutter rotations: 3300 rpm for cutting under the underwater cutting method.

(Example 3) The production of nuclear particles was performed in the same manner as in Example 1 except that the cutting was performed under the condition that the number of rotations of the cutter was 3300 rpm during cutting under the underwater cutting method.

(Example 4) Except for the production of nuclear particles, the discharge volume per unit area of the die hole: 13 kg, 0.9 kg / h · mm ² , and the discharge volume per die hole: 0.14 kg / h Extrusion was performed under the same conditions, and cutting under the underwater cutting method was performed in the same manner as in Example 1 except that cutting was performed with a cutter blade: 6 pieces.

(Example 5) In the production of core particles, a mold with a diameter of 0.55 mm and a number of mold holes of 60 was used in addition to a mold with a discharge amount of 19 kg and a discharge amount per unit area of the mold holes: 1.33 kg / h・ Extrusion amount per mm ² and per die hole: 0.32kg / h. Except when cutting in the underwater cutting method, cutting is performed with the number of cutter rotations: 1500rpm. It carried out similarly to Example 1.

(Example 6) 时 The production of composite resin particles was performed in the same manner as in Example 1 except that the amount of sodium laurylsulfonate (a 10% by mass aqueous solution) as a surfactant was 1.5 g.

(Example 7) The production of composite resin particles was carried out in the same manner as in Example 1 except that the amount of sodium lauryl sulfonate (a 10% by mass aqueous solution) added as a surfactant was 3 g.

(Example 8) In the production of core particles, it was the same as Example 5 except that 10 kg of a linear low-density polyethylene resin (made by Japan Polyethylene Co., Ltd., trade name: KERNEL KF270) was used as the ethylene-based resin. get on.

(Example 9) In the production of core particles, it was the same as in Example 5 except that 10 kg of a linear low-density polyethylene resin (made by Japan Polyethylene Co., Ltd., trade name: KERNEL KC570S) was used as the vinyl resin. get on.

(Comparative Example 1) In the production of core particles, a mold with a diameter of 0.75 mm and a number of mold holes of 30 was used in addition to a discharge amount of 21 kg, and a discharge amount per unit area of the mold holes: 1.59 kg / h・ Mm ² , Extruding volume per die hole: 0.7 kg / h. Extrusion is performed. When cutting in the underwater cutting method, cutting is performed with the number of cutter rotations: 2500 rpm. It carried out similarly to Example 1.

(Comparative example 2) In the production of core particles, a mold with a diameter of 0.75 mm and a number of mold holes of 30 was used, and the discharge volume was 21 kg, and the discharge volume per unit area of the mold holes was 1.59 kg / h. mm ² , Extruding amount per die hole: 0.7 kg / h, extrusion is performed, and when cutting in the underwater cutting method, cutting is performed with the number of cutter rotations: 2500 rpm. In the preparation of the magnesium pyrophosphate slurry used in the production of the composite resin particles, the mixed solution of deionized water, sodium pyrophosphate and magnesium nitrate was stirred at 25 ° C for 30 minutes. As a suspending agent, a 50% by volume magnesium pyrophosphate slurry having an average particle diameter of 7.2 μm was used. The amount of sodium laurylsulfonate (10% by mass aqueous solution) as a surfactant was 1.25 g. Except this, it carried out similarly to Example 1.

(Comparative Example 3) In the production of core particles, a mold with a diameter of 0.75 mm and a number of mold holes of 30 was used in addition to a discharge amount: 12 kg, and a discharge amount per unit area of the mold holes: 0.91 kg / h・ Extrusion amount per mm ² and per die hole: 0.40 kg / h. Except when cutting in the underwater cutting method, cutting is performed with the number of cutter rotations: 3500 rpm. It carried out similarly to Example 1.

(Comparative Example 4) In the production of nuclear particles, in addition to the discharge amount: 33 kg, the discharge amount per unit area of the die hole: 2.31 kg / h · mm ² , and the discharge amount per die hole: 0.37 kg / h Extrusion was performed under the same conditions, and cutting was performed under the condition of the number of cutter rotations: 3500 rpm for cutting under the underwater cutting method. The cutting was performed in the same manner as in Example 1.

(Comparative Example 5) 时 In the production of core particles, it was the same as Example 5 except that 10 kg of a linear low-density polyethylene resin (made by Japan Polyethylene Co., Ltd., trade name: KERNEL KC573) was used as the vinyl resin. get on.

(Comparative Example 6) 时 In the production of composite resin particles, in addition to using 150 g of core particles, and using a mixed monomer of 135 g of styrene and 15 g of butyl acrylate as the first monomer and 200 g of styrene as the second monomer, The system was carried out in the same manner as in Example 5.

(Comparative Example 7) In the production of composite resin particles, in addition to using 24 g of core particles and using a mixed monomer of 9 g of styrene and 15 g of butyl acrylate as the first monomer and 452 g of styrene as the second monomer, The system was carried out in the same manner as in Example 5.

(Comparative Example 8) 时 During the production of the magnesium pyrophosphate slurry used in the production of the composite resin particles, the mixed solution of deionized water, sodium pyrophosphate, and magnesium nitrate was stirred at 25 ° C for 30 minutes. As a suspending agent, a 50% by volume magnesium pyrophosphate slurry having an average particle diameter of 7.2 μm was used. The amount of sodium laurylsulfonate (10% by mass aqueous solution) as a surfactant was 1.25 g. Except this, it carried out similarly to Example 1.

Table 1 and Table 2 show the measurement results of weight, L / D, and MFR for the core particles of Examples 2 to 9 and Comparative Examples 1 to 8 in the same manner as in Example 1. In addition, in the same manner as in Example 1, for the composite resin particles, expanded particles, and molded bodies of Examples 2 to 9, and Comparative Examples 1 to 8, the content ratio of the component (PE) derived from the vinyl resin was Styrene-based monomer (St) content ratio, average volume particle size, average particle size dispersion, average aspect ratio, absorbance ratio, coefficient of variation of absorbance ratio, apparent density, and various evaluations of the molded body The results are shown in Tables 3 and 4.

As can be seen from Tables 1 to 4, the composite resin particles of the Examples had a relatively small 63% volume average particle diameter, average particle diameter dispersion, and aspect ratio. The foamed composite resin molded body obtained by molding the foamed particles obtained by foaming such composite resin particles has good internal fusion, excellent compression rigidity and flex resistance, and can suppress breakage due to deformation. Such composite resin particles and foamed particles can be obtained by having a specific aspect ratio and dispersion degree, using core particles with a smaller particle size, and further adjusting the polymerization formula.

In contrast, in Comparative Example 1 and Comparative Example 2, the average particle diameter of the composite resin particles was large, and the particle diameter of the foamed particles was relatively large. Therefore, in a mold for manufacturing a thin molded body, a filling failure occurred during molding. In addition, even if the thickness is increased, the coefficient of variation of the bending fracture energy of the formed body is large, and the bending fracture energy is scattered and uneven.

In Comparative Example 3 and Comparative Example 4, since the average aspect ratio of the composite resin particles was too large, the filling property of the foamed particles deteriorated in a mold for producing a thin molded body. Moreover, even if the thickness is increased, the variation coefficients of the bending fracture energy of the molded bodies of Comparative Examples 3 and 4 are large, and the bending fracture energy is scattered and uneven.

In Comparative Example 5, the average particle diameter and average aspect ratio of the composite resin particles were relatively large. Therefore, in a mold for manufacturing a thin molded body, a filling failure occurred during molding. Further, even if the thickness is increased, the molded body of Comparative Example 5 has a low bending fracture energy. Furthermore, the coefficient of variation of the bending fracture energy becomes large, and the bending fracture energy is scattered and uneven.

The molded body produced by using the composite resin particles of Comparative Example 6 with too little styrene-based monomer has lower rigidity, lower compressive strength, and lower flexural modulus. Therefore, the molded body of Comparative Example 6 is easily deformed due to deflection, and the deflection resistance is insufficient. On the other hand, although the molded body produced by using the composite resin particles of Comparative Example 7 with too much styrene-based monomers can increase the compressive strength or the flexural modulus of elasticity, the energy for flexural fracture is insufficient, and fractures are easily caused by deformation.

In Comparative Example 8, since the average particle diameter of the composite resin particles was too large, the filling property of the foamed particles deteriorated in a mold for producing a thin molded body. In addition, even if the thickness is increased, the coefficient of variation of the bending fracture energy of the molded body of Comparative Example 8 is still large, and the bending fracture energy is scattered and uneven.

As described above, the embodiments have been described, but the present invention is not limited to the above-mentioned embodiments, and various changes can be made within a range not departing from the gist thereof.

1‧‧‧ nuclear particles

2‧‧‧ Extruder

21‧‧‧mould

22‧‧‧ cutting chamber

221‧‧‧Circulating water

23‧‧‧ Cutter

24‧‧‧ Centrifugal separator

FIG. 1 is an explanatory diagram showing the shape of the composite resin particles in the examples. FIG. 2 is an explanatory view showing a granulation apparatus for composite resin particles in the examples.

Claims (4)

A composite resin particle comprising a composite resin particle obtained by impregnating a particle containing a vinyl resin with a polymerized styrene monomer with respect to 100 parts by mass of the vinyl resin and a content ratio of a component derived from the styrene monomer It is more than 400 parts by mass and less than 1900 parts by mass, the average aspect ratio of the composite resin particles is 1.30 or less, and the 63% volume average particle diameter d63, 90% volume average particle diameter d90, and 10% volume average of the composite resin particles are The particle size d10 satisfies the relationship of the following formula I and formula II: For example, the composite resin particle of claim 1, wherein the absorbance ratio A at the wave number of 698 cm ^-1 and the wave number of 2850 cm ^-1 of the surface of the composite resin particle in the infrared absorption spectrum measured by total reflection absorption infrared spectrum analysis ₆₉₈ / A ₂₈₅₀ is 2 or less. For example, the composite resin particle of claim 2, wherein the coefficient of variation of the absorbance ratio A ₆₉₈ / A ₂₈₅₀ is 0.2 or less. A composite resin foamed particle, which is a composite resin foamed particle using a composite resin impregnated with a polymerized styrene monomer in a vinyl resin as a base resin, and 100 parts by mass of the vinyl resin is derived from the benzene. The content ratio of the components of the vinyl monomer is more than 400 parts by mass and 1900 parts by mass or less, the average aspect ratio of the composite resin foamed particles is 1.30 or less, and the apparent density of the composite resin foamed particles Da, 63% by volume The average particle diameter d63, the 90% volume average particle diameter d90, and the 10% volume average particle diameter d10 satisfy the relationship of the following formulae III to V: