JP2021031623A - Foam particles, foam moldings and composite structural members - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide foamed particles having both high foaming property and mechanical physical characteristics. Foamed particles composed of a base resin containing a polycarbonate resin having a glass transition temperature of 140 to 155 ° C. and an amorphous polyester resin having a glass transition temperature of 100 to 130 ° C. The amorphous polyester resin contains a unit derived from a cyclic diol, and the foamed particles have a bubble diameter of 50 μm or more and less than 300 μm in a cross-sectional photograph of an area of 11.9 mm2 taken at 30 times. The above-mentioned problem is solved by the foamed particles having a large bubble having a bubble diameter of 300 μm or more and 2 mm or less. [Selection diagram] Fig. 1

Description

The present invention relates to foamed particles, foamed molded products and composite structural members. More specifically, the present invention relates to foamed particles capable of giving a foamed molded product having improved mechanical properties, a foamed molded product obtained from the foamed particles, and a composite structural member.

In addition to being light, foam moldings have good processability and shape retention, and are relatively strong, so they are used in various fields such as food trays, automobile parts, building materials, civil engineering materials, and lighting equipment. ing. A polystyrene-based resin foam molded product is used when heat resistance is not particularly required, and an olefin-based resin foam molded product such as polypropylene or polyethylene is used when cushioning properties, recoverability, flexibility, etc. are required. It tends to be used.
As a resin having generally higher heat resistance than these polystyrene-based resins and olefin-based resins, there is a polycarbonate-based resin. This is a resin material that can be used in countries other than Japan, as well as in places with harsh climates such as arid areas and tropical areas. This polycarbonate resin is not only excellent in heat resistance, but also excellent in water resistance, electrical characteristics, mechanical strength, aging resistance and chemical resistance. Therefore, polycarbonate-based resins have been used as interior materials for buildings, but in recent years, they are expected to be applied to automobile parts, packaging materials, various containers, etc. by utilizing their excellent characteristics. In addition, the foam of polycarbonate resin is expected to be applied to the core material of fiber reinforced plastic due to its high heat resistance.

However, the polycarbonate resin was inferior in foamability due to its high melt viscosity and low melt tension. Further, in a molding method such as an in-mold foaming method in which foamed particles are filled in a mold and molded, the foamed particles need to be secondarily foamed until the voids in the mold are filled, and the bubble structure is maintained in a softened state. Therefore, high foaming properties are required.
Therefore, the applicant of the present application has proposed a foamed molded product in which the mechanical properties are improved to some extent by using a polycarbonate resin as a base resin and using foamed particles having bottomed holes or through holes (Japanese Patent Laid-Open No. 2016). -125041A: Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-125041

Although it is possible to obtain foamed particles having a certain degree of foaming property and mechanical property in Patent Document 1, it has been desired to provide foamed particles having higher foaming property and mechanical property.

The inventor of the present invention further investigated the polycarbonate-based foamed particles, and found that by controlling the bubble diameter constituting the foamed particles while using a base resin obtained by adding an amorphous polyester-based resin to the polycarbonate-based resin. The present invention has been completed by surprisingly finding that it is possible to provide foamed particles having excellent mechanical properties and high foamability.

Thus, according to the present invention, foamed particles composed of a base resin containing a polycarbonate resin having a glass transition temperature of 140 to 155 ° C. and an amorphous polyester resin having a glass transition temperature of 100 to 130 ° C. And
The amorphous polyester resin contains a unit derived from a cyclic diol and contains a unit.
The foamed particles are provided with small bubbles having a bubble diameter of 50 μm or more and less than 300 μm and large bubbles having a bubble diameter of 300 μm or more and 2 mm or less in a cross-sectional photograph taken of an area of ^{11.9 mm 2 at a magnification of 30 times.} The characteristic foamed particles are provided.
Further, according to the present invention, there is provided a foam molded product obtained by foam molding the above foam particles.
Further, according to the present invention, there is provided a composite structural member characterized by having the foamed molded product and a skin material laminated and integrated on the surface of the foamed molded product.

According to the present invention, it is possible to provide foamed particles having high foamability while exhibiting excellent mechanical properties.
Further, in any of the following cases, it is possible to provide foamed particles having high foamability while exhibiting more excellent mechanical properties.
(1) The number of large bubbles in one foamed particle is one.
(2) The bulk multiple is 10 to 30 times.
(3) The mass ratio of the polycarbonate resin and the amorphous polyester resin in the base resin is 5:95 to 95: 5.
(4) The cyclic diol contains one or more rings selected from a saturated hydrocarbon ring and a saturated heterocycle as constituent components.
(5) The cyclic diol is 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol or spiroglycol.
Further, in any of the following cases, a foam molded product having excellent mechanical properties can be realized.
(1) The multiple is 10 to 30 times.
(2) The maximum bending point stress is 0.6 to 1.5 MPa.
(3) The maximum bending point energy is 0.3 to 1.2 J.
(4) The flexural modulus is 10 to 20 MPa.

It is a cross-sectional photograph of the foamed particles of Examples and Comparative Examples.

(1) Foamed Particles The foamed particles of the present invention are composed of a base resin containing a polycarbonate-based resin and an amorphous polyester-based resin.
(1-1) Base Material Resin The total ratio of the polycarbonate resin and the amorphous polyester resin to the base material resin is preferably 70% by mass or more, more preferably 85% by mass or more. It may be 100% by mass.

(A) Polycarbonate-based resin The polycarbonate-based resin preferably has a polyester structure of carbonic acid and glycol or divalent phenol. From the viewpoint of further enhancing the heat resistance, the polycarbonate resin preferably has an aromatic skeleton. Specific examples of the polycarbonate resin include 2,2-bis (4-oxyphenyl) propane, 2,2-bis (4-oxyphenyl) butane, 1,1-bis (4-oxyphenyl) cyclohexane, and 1 , 1-bis (4-oxyphenyl) butane, 1,1-bis (4-oxyphenyl) isobutane, 1,1-bis (4-oxyphenyl) ethane and other polycarbonate-based resins derived from bisphenol. Be done.
Further, examples of the polycarbonate-based resin include a linear polycarbonate-based resin and a branched polycarbonate-based resin, and both of these may be blended.

The polycarbonate resin has a glass transition temperature of 140 to 155 ° C. If the glass transition temperature is less than 140 ° C., the heat resistance of the obtained foamed molded product may be insufficient. When the glass transition temperature is higher than 155 ° C., the foamability of the foamed particles may be lowered, the heat fusion integration of the foamed particles may be insufficient, and the mechanical properties of the foamed molded product may be lowered. The glass transition temperature is preferably 143 to 152 ° C, more preferably 145 to 150 ° C.
The glass transition temperature in the present invention conforms to the values measured by the methods described in JIS K7121: 1987 and JIS K7121: 2012 “Method for measuring transition temperature of plastics”.

The polycarbonate resin preferably has a weight average molecular weight of 30,000 to 90,000. If the weight average molecular weight is less than 30,000, the mechanical properties of the obtained foamed molded product may be insufficient. When the weight average molecular weight is higher than 90,000, the foamability of the foamed particles may be lowered, the heat fusion integration of the foamed particles may be insufficient, and the mechanical properties of the foamed molded product may be lowered. The weight average molecular weight is more preferably 30,000 to 70,000, and even more preferably 40,000 to 60,000.

(B) Amorphous polyester resin The amorphous polyester resin is selected from a copolymer resin of a polycarboxylic acid and a polyol. Here, the amorphous means that the heat generation peak due to crystallization and the endothermic peak due to melting of the crystal are not observed in the DSC curve obtained by the DSC measurement.

Examples of the polycarboxylic acid include terephthalic acid, isophthalic acid, 2-methylterephthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and 2,7-naphthalene. Aromatic dicarboxylic acids such as dicarboxylic acid, biphenyldicarboxylic acid, tetralindicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelliic acid, suberic acid, azelaic acid, sebacic acid, decandicarboxylic acid, dodecanedicarboxylic acid, cyclohexanedicarboxylic acid, Decalindicarboxylic acid, norbornandicarboxylic acid, tricyclodecandicarboxylic acid, pentacyclododecandicarboxylic acid, 3,9-bis (1,1-dimethyl-2-carboxyethyl) -2,4,8,10-tetraoxaspiro [ 5.5] Examples thereof include aliphatic dicarboxylic acids such as undecane and 5-carboxy-5-ethyl-2- (1,1-dimethyl-2-carboxyethyl) -1,3-dioxane.
Among them, the polycarboxylic acid is preferably terephthalic acid or isophthalic acid.

Polyols include cyclic diols.
As the cyclic diol,
1,3-Cyclobutanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,2-decahydronaphthalenedimethanol , 1,3-decahydronaphthalene methanol, 1,4-decahydronaphthaline methanol, 1,5-decahydronaphthaline methanol, 1,6-decahydronaphthaline methanol, 2,7-decahydronaphthaline methanol , A cyclic diol having a saturated hydrocarbon ring, such as tetralindimethanol, norbornene dimethanol, tricyclodecanedimethanol, pentacyclododecanedimethanol, etc.
Spiroglycol (3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane), 5-methylol-5-ethyl-2- A cyclic diol having a saturated heterocycle such as (1,1-dimethyl-2-hydroxyethyl) -1,3-dioxane,
Bisphenols such as 4,4'-(1-methylethylidene) bisphenol, methylene bisphenol (bisphenol F), 4,4'-cyclohexylidene bisphenol (bisphenol Z), 4,4'-sulfonyl bisphenol (bisphenol S) and Its alkylene oxide adduct,
Examples thereof include cyclic diols having an aromatic ring such as aromatic dihydroxy compounds such as hydroquinone, resorcin, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, and 4,4'-dihydroxydiphenylbenzophenone.
Among them, the cyclic diol is preferably 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol or spiroglycol.
The amorphous polyester resin is a polyester derived from terephthalic acid and 1,4-cyclohexanedimethanol, and a polyester derived from terephthalic acid and 2,2,4,4-tetramethyl-1,3-cyclobutanediol. It may be copolyester with.

The polyol may contain a diol other than the cyclic diol. Such diols include ethylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, polypropylene glycol, and the like. Examples thereof include chain diols such as polybutylene glycol.

From the polycarboxylic acid and the polyol, the amorphous polyester resin is selected so that the glass transition temperature is 100 to 130 ° C. The polycarboxylic acid and the polyol may be only one kind or two or more kinds, respectively. If the glass transition temperature is less than 100 ° C., the heat resistance of the obtained foamed molded product may be insufficient. If the temperature is higher than 130 ° C., the foamability of the foamed particles may be lowered, the heat-sealing integration of the foamed particles may be insufficient, and the mechanical properties of the foamed molded product may be lowered. The glass transition temperature is preferably 105 to 125 ° C, more preferably 108 to 123 ° C.

The glass transition temperature of the amorphous polyester resin is preferably lower than the glass transition temperature of the polycarbonate resin in the range of 15 to 50 ° C. If the glass transition temperatures of both resins are too close or too far apart, the appearance and mechanical properties may not be sufficiently improved. The glass transition temperature of the amorphous polyester resin is more preferably lower in the range of 20 to 45 ° C. than the glass transition temperature of the polycarbonate resin, and further preferably lower in the range of 25 to 40 ° C.

The amorphous polyester resin preferably has an IV value (intrinsic viscosity) of 0.55 to 0.80. If the IV value is less than 0.55, the mechanical properties of the obtained foamed molded product may be insufficient. When the IV value is higher than 0.80, the foamability of the foamed particles may be lowered, the heat fusion integration between the foamed particles may be insufficient, and the mechanical properties of the foamed molded product may be lowered. The IV value is more preferably 0.58 to 0.78, and even more preferably 0.60 to 0.75.

(C) Content ratio of polycarbonate resin and amorphous polyester resin The polycarbonate resin and the amorphous polyester resin are in the range of 5:95 to 95: 5 (mass ratio) in the base resin. It is preferable that it is contained in. When the content ratio of the polycarbonate resin is less than 5, the foamability of the foamed particles is lowered, the heat fusion integration between the foamed particles is insufficient, and the mechanical properties of the foamed molded product are lowered. is there. When the content ratio of the polycarbonate resin is larger than 95, the foamability of the foamed particles is lowered, the heat fusion integration between the foamed particles is insufficient, and the mechanical properties of the foamed molded product are lowered. is there. The content ratio is more preferably 10:90 to 90:10, and even more preferably 20:80 to 80:20.

(D) Other Resins and Additives The base resin may contain a resin other than the polycarbonate resin. Examples of other resins include acrylic resins, saturated polyester resins, ABS resins, polystyrene resins, polyphenylene oxide resins and the like.
If necessary, the base resin may contain additives in addition to the resin. Additives include plasticizers, flame retardants, flame retardants, antistatic agents, spreading agents, bubble regulators, fillers, colorants, weathering agents, antiaging agents, lubricants, antifogging agents, fragrances, etc. Can be mentioned.

(1-2) Composition The foamed particles of the present invention are small bubbles having a bubble diameter of 50 μm or more and less than 300 μm and small bubbles having a bubble diameter of 300 μm or more and 2 mm or less in a cross-sectional photograph of the entire foamed particles obtained by taking an area of ^{11.9 mm 2 at a magnification of 30 times.} It has a large bubble with a bubble diameter of.
Further, the number of large bubbles per foamed particle is not particularly limited and may be a plurality of large cells, but if the number is too large, the bubble ratio becomes high and the mechanical properties of the foamed molded product are deteriorated. For this reason, it is preferable that the number of large cells is one for each foamed particle, although it depends on the diameter of the large cells.
Further, it is preferable that there is a difference of 300 μm or more between the average cell diameter of the small cells and the average cell diameter of the large cells. Due to this difference, it is possible to provide foamed particles that give a foamed molded product having improved mechanical properties. A more preferred difference is 300-600 μm. Here, the average cell diameter of the small cells is preferably in the range of 100 to 250 μm, and the average cell diameter of the large cells is preferably in the range of 350 to 900 μm.

The foamed particles can be obtained by foaming the base resin.
The outer shape of the foamed particles is not particularly limited as long as the foamed molded product can be produced, and examples thereof include a spherical shape, a substantially spherical shape, and a cylindrical shape. The foamed particles preferably have an outer shape represented by an average aspect ratio of 0.7 or more (upper limit is a true sphere of 1).

The foamed particles preferably have a bulk multiple of 10 to 30 times. If the bulk multiple is less than 10 times, good mechanical properties may not be exhibited during foam molding. When the bulk factor is larger than 30 times, the open cell ratio of the foamed particles may increase, and the foamability of the foamed particles may decrease during foam molding. The bulk multiple is more preferably 10 to 25 times, and particularly preferably 10 to 20 times.

(1-3) Production Method Examples of the method for producing the foamed particles include a method in which the resin particles are vapor-impregnated with a foaming agent to obtain foamable particles, and the foamable particles are foamed.
The foamed particles can be obtained by using a known production method and production equipment. For example, foamed particles can be produced by melt-kneading a base resin using an extruder, extruding it, and then granulating it by hot-cutting, strand-cutting, or the like. The temperature, time, pressure, etc. at the time of melt-kneading can be appropriately set according to the raw materials used and the manufacturing equipment.
Hot cut is preferable for cutting and granulation, and watering hot cut is more preferable. Watering hot cut is a method of exposing the extruded resin to the atmosphere before cooling it with water. This method has an advantage that the average bubble diameter of the small cells can be made larger because the abrupt cooling of the particles can be avoided.

The melt-kneading temperature in the extruder at the time of melt-kneading is preferably 260 to 330 ° C, which is a temperature at which the raw material resin is sufficiently softened, and more preferably 270 to 300 ° C. The melt-kneading temperature means the temperature of the melt-kneaded product inside the extruder measured by measuring the temperature at the center of the melt-kneaded product flow path near the extruder head with a thermocouple thermometer.

A bubble conditioner may be supplied to the extruder. Examples of the bubble adjusting agent include polytetrafluoroethylene powder, polytetrafluoroethylene powder modified with an acrylic resin, talc and the like. The amount of the bubble adjusting agent is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the base resin. When the amount of the bubble adjusting agent is less than 0.01 parts by weight, the bubbles of the foamed particles become coarse, and the appearance of the obtained foamed molded product may be deteriorated. When the amount of the bubble adjusting agent is more than 5 parts by weight, the closed cell ratio of the foamed particles may decrease due to the bubble rupture. The amount of the bubble adjusting agent is more preferably 0.05 to 3 parts by weight, further preferably 0.1 to 2 parts by weight.

Next, as a method for producing the effervescent particles, there is a method in which the resin particles are vapor-impregnated with a foaming agent in a container that can be sealed.
Examples of the foaming agent include saturated aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane and hexane, ethers such as dimethyl ether, methyl chloride, 1,1,1,2-tetrafluoroethane, 1, Examples thereof include chlorofluorocarbons such as 1-difluoroethane and monochlorologifluoromethane, and inorganic gases such as carbon dioxide and nitrogen. Among them, dimethyl ether, propane, normal butane, isobutane and carbon dioxide are preferable, propane, normal butane, isobutane and carbon dioxide are more preferable, and normal butane, isobutane and carbon dioxide are particularly preferable. The foaming agent may be used alone or in combination of two or more.

If the amount of the foaming agent charged into the container is too small, the foamed particles may not be foamed to a desired expansion ratio. If the amount of the foaming agent is too large, the foaming agent acts as a plasticizer, so that the viscoelasticity of the base resin is excessively lowered, and the foamability is lowered, so that good foamed particles may not be obtained. Therefore, the amount of the foaming agent is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 4 parts by weight, still more preferably 0.3 to 3 parts by weight with respect to 100 parts by weight of the raw material resin.

Further, as a method for producing the foamed particles, a method of heating with a heating medium such as steam in a container that can be sealed can be mentioned. Examples of the heating conditions include a gauge pressure of 0.3 to 0.5 MPa, a temperature of 120 to 159 ° C., and 10 to 180 seconds.
The particle size of the foamed particles can be changed by changing the diameter of the multi-nozzle mold attached to the front end of the extruder.

(2) Effervescent molded product The foamed molded product can be obtained by foam-molding the foamed particles.

(2-1) Base Material Resin The base material resin constituting the foamed molded product is the same as the base material resin of the foamed particles.

(2-2) Physical properties In ^{the cross-sectional photograph of the foam molded product taken at an area of 11.9 mm 2 at} a magnification of 30 times, small bubbles having a bubble diameter of 50 μm or more and less than 300 μm and large cells having a bubble diameter of 300 μm or more and 2 mm or less. And have.
Further, the number of large bubbles per foamed particle is not particularly limited and may be a plurality of large cells, but if the number is too large, the bubble ratio becomes high and the mechanical properties of the foamed molded product are deteriorated. For this reason, it is preferable that the foamed particles have only one large bubble in one of them, although it depends on the diameter of the large cell.
Further, it is preferable that there is a difference of 500 μm or more between the average cell diameter of the small cells and the average cell diameter of the large cells. Due to this difference, it is possible to provide foamed particles that give a foamed molded product having improved mechanical properties. A more preferred difference is 500-1500 μm. Here, the average cell diameter of the small cells is preferably in the range of 100 to 250 μm, and the average cell diameter of the large cells is preferably in the range of 500 to 1600 μm.

The outer shape of the fused foam particles is not particularly limited as long as the foamed molded product can be maintained.
The multiple of the foam molded product is preferably 10 to 30 times. If the multiple is less than 10 times, the advantage of foaming may be diminished due to the increased weight. If the multiple is greater than 30 times, the mechanical properties may be insufficient. The multiple is more preferably 10 to 27 times, and particularly preferably 10 to 25 times.

The maximum bending point stress of the foam molded product is preferably 0.6 to 1.5 MPa. If the maximum bending stress is too small, the foamed part may break easily.

The maximum bending point energy of the foam molded product is preferably 0.3 to 1.2 J. If the maximum bending point energy is less than 0.3 J, the shock absorption performance may be insufficient. If the maximum bending point energy is larger than 1.2 J, the elastic modulus may decrease and the strength may be insufficient.

The flexural modulus of the foam molded product is preferably 10 to 20 MPa. If the flexural modulus is too small, the foamed molded product may be deformed by the pressure applied when laminating and integrating a skin material such as fiber reinforced plastic on the surface of the foamed molded product.

(2-3) Manufacturing Method As a manufacturing method of a foamed molded product, foamed particles are filled in a cavity of a mold, a heating medium is supplied into the cavity, and the foamed particles are heated to refoam and refoam. Examples thereof include a method of obtaining a foamed molded product by heat-sealing and integrating the foamed particles with each other by these foaming pressures. Examples of the heating medium include steam, hot air, hot water and the like, and steam is preferable.

(2-4) Applications The foamed molded product is excellent in light weight, heat resistance and mechanical properties, and in particular, is excellent in load bearing capacity in a high temperature environment. Therefore, for example, it can be suitably used for parts of transportation equipment such as automobiles, aircraft, railway vehicles, and ships. Examples of automobile parts include parts used in the vicinity of an engine, exterior materials, and the like.

According to the present invention, an automobile part composed of the foam molded product of the present invention is provided, and examples of the automobile part include a floor panel, a roof, a bonnet, a fender, an undercover, a wheel, a steering wheel, and a container. Parts such as (housing), hood panel, suspension arm, bumper, sun visor, trunk lid, luggage box, seat, door, and cowl can be mentioned.

(Composite structural member)
A skin material may be laminated and integrated on the surface of the foam molded product and used as a composite structural member. When the foamed molded product is a foamed sheet, it is not necessary that the foamed molded product is laminated and integrated on both sides of the foamed molded product, and it is sufficient that the skin material is laminated and integrated on at least one of both sides of the foamed molded product. The lamination of the skin material may be determined according to the use of the composite structural member. In particular, considering the surface hardness and mechanical properties of the composite structural member, it is preferable that the skin material is laminated and integrated on both sides of the foam molded product in the thickness direction.

The skin material is not particularly limited, and examples thereof include fiber reinforced plastics, metal sheets, and synthetic resin films. Of these, fiber reinforced plastics are preferable. A composite structural member using a fiber reinforced plastic as a skin material is called a fiber reinforced composite.
Reinforcing fibers that make up fiber-reinforced plastics include glass fibers, carbon fibers, silicon carbide fibers, alumina fibers, tyranno fibers, genbuiwa fibers, ceramic fibers and other inorganic fibers; stainless fibers, steel fibers and other metal fibers; aramid. Organic fibers such as fibers, polyethylene fibers, polyparaphenylene benzoxazole (PBO) fibers; boron fibers can be mentioned. The reinforcing fibers may be used alone or in combination of two or more. Among them, carbon fiber, glass fiber and aramid fiber are preferable, and carbon fiber is more preferable. Despite being lightweight, these reinforcing fibers have excellent mechanical properties.

The thickness of the fiber reinforced plastic is preferably 0.02 to 2 mm, more preferably 0.05 to 1 mm. Fiber reinforced plastics having a thickness within this range are excellent in mechanical properties despite being lightweight.
Basis weight of the fiber reinforced plastic is preferably 50~4000g / m ^2, and more preferably 100 to 1000 g / m ^2. Fiber reinforced plastics having a basis weight within this range are excellent in mechanical properties despite being lightweight.

Examples of the method used for molding fiber reinforced plastics include an autoclave method, a hand lay-up method, a spray-up method, a PCM (Prepreg Compression Molding) method, an RTM (Resin Transfer Molding) method, and a VaRTM (Vacum assisted Resin Transfer) method. Law etc. can be mentioned.

The composite structural member thus obtained is excellent in heat resistance, mechanical strength and light weight. Therefore, it can be used in a wide range of applications such as transportation equipment fields such as automobiles, aircrafts, railway vehicles, and ships, home appliances fields, information terminal fields, and furniture fields.
For example, a fiber-reinforced composite is a transportation equipment component, a transportation equipment component including a structural component constituting the main body of the transportation equipment (particularly an automobile part), a windmill wing, a robot arm, a cushioning material for a helmet, and the like. It can be suitably used as a transport container such as an agricultural product box and a heat and cold insulation container, a rotor blade of an industrial helicopter, and a parts packing material.
Automotive parts include, for example, floor panels, roofs, bonnets, fenders, undercovers, wheels, steering wheels, containers (housings), hood panels, suspension arms, bumpers, sun visors, boot lids, luggage boxes, seats, etc. Parts such as doors and cowls can be mentioned.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the present examples. First, the measurement method and the evaluation method in Examples and Comparative Examples will be described.

(Average cell diameter)
The average cell diameter of the foamed particles was measured as follows.
First, the cut surface was photographed with a scanning electron microscope (“SU1510” manufactured by Hitachi High-Technologies Corporation) at a magnification of 30 times to ^{an area of 11.9 mm 2.} For the foamed particles, the central part of the cross section divided into two at the central part of the foamed particles was photographed.
The captured image was printed on A4 paper, the bubble diameter was calculated for all the bubbles displayed on the printing unit, and the average bubble diameter was calculated based on each bubble diameter.
The bubble diameter was a value obtained by measuring the major axis and the minor axis of the cell cross section and using the arithmetic mean value of the minor axis and the major axis. Specifically, any two points having the maximum mutual distance on the outer contour line of the cross section of the bubble were selected, and the distance between these two points was defined as the "major axis of the bubble". Also, from any two points where the straight line orthogonal to the major axis of the bubble and the outer contour line of the bubble cross section intersect, select any two points that maximize the mutual distance, and set the distance between these two points as ""Short diameter of bubbles".

(Bulk density and bulk multiple)
The bulk density was measured according to JIS K6911: 1995 "General Test Method for Thermosetting Plastics". That is, the measurement was performed using an apparent density measuring device conforming to JIS K6911, and the bulk density was measured based on the following formula.
Bulk density of foamed particles (kg / m ³ ) = [Weight of graduated cylinder containing sample (kg) -Weight of graduated cylinder (kg)] / [Volume of graduated cylinder (m ³ )]
The bulk multiple is a value obtained by integrating the resin density with the reciprocal of the bulk density.

(Density of foam molded product)
The mass (a) and volume (b) of the test piece cut out from the foamed molded product (dried at 60 ° C. for 20 hours or more after molding) were measured so as to have three or more significant figures, respectively, and the formula (a) was obtained. ) / (B) was used to determine ^{the density (kg / m 3) of the foamed molded product.}

(Bending test: maximum point stress and energy)
The stress and energy at the maximum point were measured by a method based on JIS K7221-1: 2006 "Hard foamed plastic-Bending test-Part 1: How to determine the deflection characteristics". That is, a rectangular parallelepiped-shaped test piece having a length of 20 mm, a width of 25 mm, and a height of 130 mm was cut out from the foam molded product. A Tencilon universal testing machine (“UCT-10T” manufactured by Orientec Co., Ltd.) was used for the measurement. The maximum bending point stress of the bending strength was calculated using a universal testing machine data processing system (“UTPS-237S Ver, 1.00” manufactured by Softbrain Co., Ltd.).
A strip-shaped test piece was placed on a support base, and the maximum bending point stress was measured under the conditions of a load cell of 1000 N, a test speed of 10 mm / min, a support base tip jig 5R, and an opening width of 100 mm. The number of test pieces shall be 5 or more, and the same shall apply after adjusting the condition for 16 hours under the JIS K 7100: 1999 symbol "23/50" (temperature 23 ° C., relative humidity 50%) and a second-class standard atmosphere. Measured under standard atmosphere. The arithmetic mean values of the maximum bending point stress and energy of each test piece were taken as the maximum bending point stress and energy of the foamed molded product, respectively.

The flexural modulus was measured by a method based on JIS K7221-1: 2006 "Hard foamed plastic-Bending test-Part 1: Deflection characteristics". That is, a rectangular parallelepiped-shaped test piece having a length of 20 mm, a width of 25 mm, and a height of 130 mm was cut out from the foam molded product. A Tencilon universal testing machine (“UCT-10T” manufactured by Orientec Co., Ltd.) was used for the measurement. The flexural modulus was calculated using a universal testing machine data processing system (“UTPS-237S Ver, 1.00” manufactured by Softbrain Co., Ltd.). The number of test pieces shall be 5 or more, and the same shall apply after adjusting the condition for 16 hours under the JIS K 7100: 1999 symbol "23/50" (temperature 23 ° C., relative humidity 50%) and a second-class standard atmosphere. Measured under standard atmosphere. The arithmetic mean value of the compressive elastic modulus of each test piece was taken as the flexural modulus of the foamed molded product.
The flexural modulus was calculated by the following equation using the straight part at the beginning of the load-deformation curve.
E = Δσ / Δε
E: Flexural modulus (MPa)
Δσ: Difference in stress between two points on a straight line (MPa)
Δε: Deformation difference (%) between the same two points
The flexural modulus per unit density was calculated by dividing the flexural modulus by the density of the foamed molded product.

(Example 1)
(Resin particle manufacturing process)
Polycarbonate resin (glass transition temperature 148 ° C., weight average molecular weight 48,000, melt mass flow rate 13 g / 10 minutes, specific gravity 1.20) and amorphous polyester resin (glass transition temperature 110 ° C., IV value 0.72) , Specific gravity 1.18) was collected at a molecular weight ratio of 60:40 and dried at 100 ° C. for 5 hours. The obtained dried product (base resin) was supplied to a single-screw extruder having a diameter of 40 mm at a rate of 10 kg / hr per hour and melt-kneaded at 280 ° C. Next, extrude into the chamber from the die holes (4 nozzles with a diameter of 1.0 mm are arranged) of the die (temperature: 280 ° C., resin pressure on the inlet side: 18 MPa) mounted on the tip of the single-screw extruder, and 4 pieces. The rotation axis of the rotary blade having the cutting blade of No. 1 was rotated at a rotation speed of 5400 rpm to cut into particles. The cut resin was once exposed to air and then cooled with cooling water to prepare resin particles.

(Immersion process)
100 parts by mass of the resin particles were sealed in a pressure vessel, the inside of the pressure vessel was replaced with carbon dioxide, and then carbon dioxide was press-fitted to an impregnation pressure of 0.9 MPa. The mixture was allowed to stand in an environment of 20 ° C., and the pressure vessel was decompressed after the impregnation time of 24 hours had elapsed. In this way, the resin particles were impregnated with carbon dioxide to obtain effervescent particles.

(Foam process)
Immediately after the decompression in the impregnation step, the foamable particles are taken out from the pressure vessel, and then the impregnated material is foamed by steam in a high-pressure foam tank while stirring at a foaming temperature of 128 ° C. for 60 seconds using steam. I let you. After foaming, the particles were taken out from the high-pressure foam tank and dried in an air flow dryer to obtain foamed particles.

(Molding process)
The obtained foamed particles were left at room temperature (23 ° C.) for 1 day, sealed in a pressure vessel, and compressed air was press-fitted into the pressure vessel to an impregnation pressure (gauge pressure) of 0.5 MPa. It was allowed to stand in an environment of 20 ° C., and pressure curing was carried out for 24 hours. After taking out, it is filled in a molding mold of 30 mm × 300 mm × 400 mm, heated with steam of 0.3 MPa for 60 seconds, and then cooled until the maximum surface pressure of the foamed molded product drops to 0.02 MPa. Then, a foam molded product was obtained.

(Example 2)
In the foaming step, foamed particles and a foamed molded product were obtained in the same manner as in Example 1 except that the mixture was stirred at a foaming temperature of 128 ° C. for 70 seconds.

(Example 3)
In the foaming step, foamed particles and a foamed molded product were obtained in the same manner as in Example 1 except that the mixture was stirred at a foaming temperature of 128 ° C. for 80 seconds.

(Example 4)
In the foaming step, foamed particles and a foamed molded product were obtained in the same manner as in Example 1 except that the mixture was stirred at a foaming temperature of 128 ° C. for 90 seconds.

(Comparative Example 1)
(Resin particle manufacturing process)
Polycarbonate resin (glass transition temperature 148 ° C., weight average molecular weight 48,000, melt mass flow rate 13 g / 10 minutes, specific gravity 1.20) and amorphous polyester resin (glass transition temperature 110 ° C., IV value 0.72) , Specific gravity 1.18) was collected at a molecular weight ratio of 60:40 and dried at 100 ° C. for 5 hours. The obtained dried product (base resin) was supplied to a single-screw extruder having a diameter of 40 mm at a rate of 15 kg / hr per hour and melt-kneaded at 280 ° C. Next, cooling water at about 60 ° C. is poured from the die holes (9 nozzles with a diameter of 1.0 mm are arranged) of the die (temperature: 300 ° C., resin pressure on the inlet side: 14 MPa) mounted on the tip of the single-screw extruder. Resin particles were produced by extruding into the housed chamber, rotating the rotating shaft of a rotary blade having six cutting blades at a rotation speed of 5000 rpm, and cutting into granules.
Although foamed particles were obtained in the same manner as in Example 1 except for the resin particle manufacturing step, only foamed molded products up to 10 times were obtained.

(Comparative Example 2)
Foamed particles were obtained in the same manner as in Comparative Example 1 except that the temperature of the cooling water was 80 ° C., but a foamed molded product could not be obtained.

Table 1 shows the physical characteristics of Examples and Comparative Examples. In addition, cross-sectional photographs of the foamed particles of Examples and Comparative Examples are summarized in FIG. In the comparative example, the foam molded product could not be molded.

From Table 1 and FIG. 1, it can be seen that under the conditions of the comparative example, foamed particles having a small average particle size of small cells are formed. In particular, it can be seen that under the conditions of Comparative Example 2, foamed particles having no large bubbles are formed.
From Table 1, foaming is performed while using a base resin containing a polycarbonate resin having a specific glass transition temperature and an amorphous polyester resin having a specific glass transition temperature and containing a unit derived from a cyclic diol. It can be seen that by controlling the diameter of the bubbles constituting the particles, it is possible to produce a foam molded product having excellent magnification and excellent mechanical properties. Further, since the foam molded product could not be molded in the comparative example, it can be seen that if the average particle size of the small cells is too small, it cannot be used as the foam molded product.

Claims (14)

Foamed particles composed of a base resin containing a polycarbonate resin having a glass transition temperature of 140 to 155 ° C. and an amorphous polyester resin having a glass transition temperature of 100 to 130 ° C.
The amorphous polyester resin contains a unit derived from a cyclic diol and contains a unit.
The foamed particles are provided with small bubbles having a bubble diameter of 50 μm or more and less than 300 μm and large bubbles having a bubble diameter of 300 μm or more and 2 mm or less in a cross-sectional photograph taken of an area of ^{11.9 mm 2 at a magnification of 30 times.} Characterized foam particles. The foamed particle according to claim 1, wherein the number of the large bubbles in one foamed particle is one. The foamed particles according to claim 1 or 2, wherein the foamed particles have a bulk multiple of 10 to 30 times. The foamed particles according to any one of claims 1 to 3, wherein the mass ratio of the polycarbonate resin to the amorphous polyester resin in the base resin is 5:95 to 95: 5. The foamed particle according to any one of claims 1 to 4, wherein the cyclic diol contains one or more rings selected from a saturated hydrocarbon ring and a saturated heterocycle as constituent components. The foamed particle according to any one of claims 1 to 5, wherein the cyclic diol is 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol or spiroglycol. A foamed molded product obtained by foam-molding the foamed particles according to any one of claims 1 to 6. The foamed molded product according to claim 7, wherein the foamed molded product has a multiple of 10 to 30 times. The foamed molded product according to claim 7 or 8, wherein the maximum bending point stress of the foamed molded product is 0.6 to 1.5 MPa. The foamed molded product according to any one of claims 7 to 9, wherein the maximum bending point energy of the foamed molded product is 0.3 to 1.2 J. The foamed molded product according to any one of claims 7 to 10, wherein the foamed molded product has a flexural modulus of 10 to 20 MPa. A composite structural member comprising the foamed molded product according to any one of claims 7 to 11 and a skin material laminated and integrated on the surface of the foamed molded product. The composite structural member according to claim 12, wherein the skin material is a fiber reinforced plastic. The composite structural member according to claim 12 or 13, wherein the composite structural member is used for any of a wind turbine blade, a robot arm, and an automobile component.