JP2001316512A - Foamed polystyrene-based resin molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a recyclable foamed styrene-based resin molding. SOLUTION: The subject is solved by a foamed styrenic resin molding characterized in that the resin molding is obtained by subjecting pre-expanded particles obtained by expanding foamable styrenic-resin particles by 20-70 times in bulkiness and having 1.2-2.0 maximum foaming capacity to extrusion foaming and has 0-60% fusion ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to recycling of a foamed styrene resin molded article used for a packing material for home electric appliances or the like or a heat insulating material for a house or the like, and more particularly to crushing after use. The present invention relates to a foamed styrene-based resin molded product which is easy to obtain and easily obtains crushed particles suitable for recycling, and a foamed crushed particle mixed molded product obtained by mixing the crushed particles.

[0002]

2. Description of the Related Art A foamed styrene resin molded article is widely used as a packing material for home electric appliances and the like and a heat insulating material for houses and the like. However, in recent years, from the viewpoint of increasing awareness of environmental issues, there is a demand for a material having excellent recyclability so that it can be recycled after use in terms of resource protection and waste disposal. Conventionally, various methods have been proposed as a method of recycling a foamed styrene resin molded article. In particular, the following means has been proposed as a method of reusing a foamed molded article after cutting or crushing it into small pieces.

[0003] Japanese Patent Application Laid-Open No. Sho 50-1 discloses a cutting method.
50769, JP-A-4-108834, JP-A-4-108835, JP-A-7-156181
No. 6,086,098 is known. However, in these methods, it is necessary to cut the used expanded styrene-based resin molded article into square strips using a sharp blade or a hot wire, and the number of complicated steps increases, resulting in a large increase in cost for recycling. turn into. Therefore, JP-A-53-61658 and JP-A-6-182890 propose a method of crushing a foamed molded product into small pieces and reusing them. According to such a method, a used compact is crushed by a crusher into small pieces, and the small pieces are mixed with unused pre-expanded particles as a raw material to foam again to produce a compact. Therefore, the crushed and mixed granulated product can be reused without going through a complicated process.

[0004]

However, in these methods, a rotary cutter type crusher or an impact type crusher (hammer mill) is usually used as a crusher. Torn or crushed by the shear or frictional force of the machine,
There is a problem that the closed cell structure of the obtained crushed particles is broken and reduced. In addition, the shape of the crushed particles obtained by such a method is irregular, there is also a variation in size,
Many fine powdery crushed grains are also present. Such crushed particles have little foaming power because the residual ratio of the closed cell structure is low. Therefore, even if such a crushed particle is filled in a mold and heated by steam, foaming sufficient to fill voids between particles cannot be obtained.

[0005] Even if the foam is temporarily expanded and expanded, the shrinkage after molding is severe, and the molded article obtained is inferior. Also, in the above method, unused pre-expanded particles are mixed with the crushed particles, but since the unused pre-expanded particles have a strong foaming power, even if the crushed particles have a slight foaming power, they are crushed. Thus, there is a problem that the crushed particles have a contracted shape. Further, since the pre-expanded particles are excessively expanded, the obtained molded article partially has high foaming, and there is a problem that the strength of the entire molded article is reduced. In addition, since the crushed particles have irregular shapes and irregular sizes, the mixed state with the pre-expanded particles is likely to be non-uniform, and there is also a problem that poor filling or partial shrinkage occurs.

[0006] Furthermore, the mixing ratio of such crushed particles is as follows:
The limit is about 20% with respect to the total volume of the crushed particles and the pre-expanded particles, and if the mixing ratio is more than that, the physical strength of the molded product is extremely reduced, and the appearance of the molded product is also significantly reduced. As described above, with the conventional technique, it was not possible to efficiently recycle the molded body, and it was difficult to put it to practical use.

[0007]

Even if a crusher usually used for collecting and recycling waste such as foamed plastic can be crushed to a uniform particle size without losing the closed-cell structure as much as possible, it is regenerated. When used, the mixing ratio of the crushed particles can be increased, and the recyclability can be further improved. Therefore, an object of the present invention is to obtain a high-quality molded article by reusing crushed particles obtained by crushing even when used, while performing a sufficient function as a foamed styrene resin molded article. An object of the present invention is to provide a foamed styrene-based resin molded product, crushed particles thereof, and a foamed crushed particle mixed molded product obtained by mixing the crushed particles.

[0008]

Means for Solving the Problems The present inventor paid attention to the relationship between the fusion rate and the physical properties of a foamed styrenic resin molded article, and as a result of intensive research, found that the pre-expanded particles were re-foamed under certain conditions. The inventors have found that the above problems can be solved by adjusting the foaming ability of the re-expanded particles obtained and the heating conditions during foam molding, and have completed the present invention. Thus, according to the present invention, the maximum foaming ability obtained by foaming the expandable styrene-based resin particles by a factor of 20 to 70 times is 1.
A foamed styrenic resin molded article (hereinafter referred to as “foamed foam”) obtained by subjecting pre-expanded particles of 2 to 2.0 to foam molding by heating with steam or the like and having a fusion rate of 0 to 60%. Molded article) is provided.

Further, according to the present invention, the maximum foaming ability obtained by crushing the foam molded article with a crusher is 1.2.
A styrene foam resin crushed particle (hereinafter referred to as a “crushed particle”) having a particle size of from 1.6 to 1.6 is provided. Furthermore, according to the present invention, the content ratio of the crushed particles obtained by mixing the crushed particles and the pre-expanded particles obtained by expanding the expandable styrene resin particles to a predetermined multiple is 10 to 60 in volume ratio. % Of the mixed particles (hereinafter, referred to as “mixed molded body”).

[0010] The foamed molded article of the present invention has sufficient properties of the foamed resin molded article such as compressive strength and bending strength.
It can be suitably used for applications such as packing materials for home appliances and heat insulating materials for houses and the like. Also, when crushing with a crusher,
Since the pre-expanded particles are easily broken at the interface and are hardly torn or crushed by shearing and friction, it is possible to obtain crushed particles while maintaining the closed cell structure. Therefore, the crushed particles of the present invention are often crushed into a state close to the unit of the pre-expanded particles, are uniform in shape and size, and hardly generate fine powdery crushed materials. Therefore, it is easy to classify the crushed particles to make the particle size uniform, and almost no crushed material to be discarded is generated.
As described above, since the crushed particles of the present invention maintain the closed-cell structure at a high dimension, they can be mixed with the pre-expanded particles at a high ratio, and a mixed molded body that can exhibit good physical properties can be obtained. .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The foamed molded article of the present invention is obtained by foaming prefoamed particles having a maximum foaming ability of 1.2 to 2.0, obtained by foaming expandable styrene-based resin particles by a factor of 20 to 70 times, with heated steam. And a fusion rate of 0 to 60%.

(Expandable Styrene Resin Particles) The expandable styrene resin particles used in the present invention are usually prepared by suspending a styrene monomer in water and subjecting it to suspension polymerization in the presence of a polymerization initiator. Before or after the completion of the styrene-based polymer particles, or by impregnating with a foaming agent or the like, or as disclosed in JP-A-49-2994, by suspending styrene-based polymer particles in water, Seed polymerization in the presence of a polymerization initiator by supplying the monomer continuously or intermittently,
It is manufactured by adding and impregnating a foaming agent or the like before or after completion of the polymerization. Examples of the styrene-based monomer include styrene alone or a combination of styrene and a monomer polymerizable with styrene.

Examples of monomers polymerizable with styrene include styrene derivatives such as α-methylstyrene, acrylic acid, methacrylic acid, methacrylic esters, acrylic esters, and divinylbenzene. Examples of the blowing agent include aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, and cyclopentane; and halogenated carbons such as HCFC-141b. These may be used alone or in combination of two or more. They can be used in combination. The amount of the foaming agent used is appropriately adjusted depending on the desired foaming multiple, and is not particularly limited.
It is preferably about 0% by weight, more preferably about 3 to 12% by weight. Also, when polymerizing the styrene monomer,
If desired, various additives may be added. Examples of such additives include an antioxidant, a lubricant, a flame retardant, a flame retardant auxiliary, and an antistatic agent.

(Pre-expanded Particles) The pre-expanded particles used in the present invention can be obtained by pre-expanding the expandable styrene resin particles obtained as described above by heating them with steam or the like. The heating temperature is preferably about 95 to 100 ° C. The pressure of the steam is 0.03 to 0.08 kgf /
cm ² is preferable. The pre-expanded particles used in the present invention are obtained by expanding the bulk number 20 to 70 times, preferably 30 to 60 times. The bulk multiple of the pre-expanded particles is a value obtained by placing a predetermined weight of the pre-expanded particles in a measuring container such as a measuring cylinder, measuring the bulk capacity, and dividing the volume by the weight.

(Expansion ability) The expansion ability of the pre-expanded particles used in the expanded molded article of the present invention is measured by immersing the pre-expanded particles in a large amount of boiling water, heating the pre-expanded particles for a predetermined period of time, and measuring by the measurement method described later. I do. The maximum foaming capacity measured by heating every predetermined time is defined as the maximum foaming capacity. The maximum foaming ability of the pre-expanded particles is from 1.2 to 2.0, preferably from 1.3 to 1.8. When the maximum foaming capacity is lower than 1.2, even if the pre-expanded particles are foamed by raising the heating steam pressure to 0.4 kgf / cm ² or more, only a pomegranate-like foamed article having a low strength is obtained. Flexural strength is significantly reduced. Conversely, if the maximum foaming ability exceeds 2.0, a foamed molded article having a fusion rate exceeding 60% is easily obtained, and the fusion rate of the foamed molded article fluctuates due to a slight change in the heating steam pressure during molding. Therefore, it is difficult to obtain a primary molded body having a stable fusion rate. The foaming ability can be adjusted by changing the amount of the foaming agent used in the expandable styrene resin particles, the degree of polymerization of the styrene resin, the degree of crosslinking, the aging time of the pre-expanded particles, and the like. For example, when the expansion ratio of the target pre-expanded particles is 50 times, the usage amount of the blowing agent is 3 to 8
The maximum foaming capacity is reduced to 1.2 to
It can be adjusted to 2.0.

(Expanded Styrenic Resin Molded Article, Expanded Molded Article) The expanded molded article of the present invention is obtained by filling pre-expanded particles into a mold for an expanded molded article having a large number of small holes, and foam-forming with steam or the like. It can be manufactured by fusing the foamed particles to each other, cooling, and taking out from the mold. In the foam molding process, the pressure of the heating steam is usually 0.4 to 1.2 kgf / cm.
^{About 2} and preferably about 0.6 to 0.9 kgf / cm ² .

(Fusion rate) The fusion rate of the foam molded article of the present invention is from 0 to 60%, more preferably from 0 to 40%. The measurement of the fusion ratio of the foamed molded article was performed by placing a crack having a depth of about 5 mm on the surface of the foamed molded article with a knife, breaking the molded article along the crack, observing the fracture surface, and measuring the total particle size. It can be obtained by calculating the ratio of the number of broken particles to the number of particles themselves. Generally, the fusion ratio of the foam molded article is 60%.
When the value was lower than the above, it was evaluated that the molded product was defective. However, when the physical property strength of the molded article having a fusion rate of 0 to 60% is actually measured, the foam molded article of the present invention has sufficient physical properties, despite the low fusion rate, and has an energy-saving property. It has been found to have excellent features in terms of recycling. Among them, it was found that the compressive strength did not decrease at all, but rather the compressive strength was sometimes higher than that of a molded article having a fusion ratio exceeding 60%.
This is completely opposite to the conventional knowledge.

The reason for this is that when the fusion rate is increased, the heating pressure is often set to a higher value. For this reason, an increase in the internal pressure may cause cell destruction or specific gravity unevenness, or a partial flattening of the foamed particles may occur. It is considered that it has occurred. In general, among the physical properties of a foam molded article, the bending strength tends to decrease as the fusion rate decreases. However, the maximum foaming capacity of the re-expanded particles is 1.2 to 2.0.
In the range, even if the fusion rate is 0%, the decrease in bending strength is small, and is 15% less than the bending strength at a fusion rate of 100%.
It was found that the degree had only decreased. Flexural strength is 1
If the decrease is about 5%, it can be dealt with by increasing the density of the molded body or increasing the amount of the molded body used. Therefore, it is not a serious problem in view of the merit that recycling is easy.

The reason why the bending strength is not extremely reduced even when the fusion rate is 0% is that there is no void between the pre-expanded particles and cracks are hardly generated, so that the particles are hardly broken. Is considered as the reason.
Further, even if the fusion rate is 0%, it is presumed that each foamed particle is less likely to be broken because it is fused in a dotted manner at a part of the interface. Also, even if the fusion is performed at the interface of the expanded particles, the fusion strength is not as strong as that of the pre-expanded particles. The fusion ratio in the foam molded article may be adjusted by the conditions at the time of foam molding or by performing a surface treatment on the foamed pre-expanded particles. Molding conditions for adjusting the fusion rate of the foam molded article include, for example, lowering the fusion rate by lowering the pressure of the heated steam or shortening the heating time such as double-sided heating.

Further, in order to prevent the particles of the pre-expanded particles from coalescing with each other, for example, zinc stearate, magnesium stearate, calcium carbonate or the like, or other organic surface treating agents may be used. The amount of the surface treatment agent used is about 0.3% by weight or less based on the weight of the pre-expanded particles. Clogging of the pores with the surface treatment agent is likely to occur, which is not preferable. The expansion multiple of the foamed molded article of the present invention is preferably about 20 to 70 times, and more preferably about 30 to 60 times. If the foaming multiple exceeds 70 times, the cell membrane becomes thin, so that the closed cell ratio is reduced due to foam breakage, and the physical properties such as impact resistance of the foamed molded product are undesirably reduced. Conversely, if the foaming multiple is lower than 20, the weight of the foamed molded article increases and the transportation cost increases, which is not preferable.

(Crushed Granules) Known crushing means can be used for crushing the foam molded article. Specifically, an impact crusher, a shear crusher, or the like is used as a dry crusher.
Further, in order to make the crushed particles have a certain size range, it is preferable to sieve using a means such as classification. In particular, it is preferable to remove finely crushed pieces of 1 mm or less in order to prevent the floating of powder on the surface of the mixed molded product and poor appearance, and also to prevent clogging of small holes in the mold during production. As for the particle size of the crushed pieces of the present invention, the length of the minor axis is preferably 2 to 7 mm, more preferably 2 to 5 mm. The length of the minor axis is a value obtained by measuring the shortest part among the vertical, horizontal, and height of the largest crushed particle among various sizes of crushed particles. If the short diameter of the crushed particles exceeds 7 mm, the filling port of the molding machine is easily clogged, and the filling property is deteriorated. Also,
When the minor axis is less than 2 mm, finely crushed pieces are increased, and clogging of small holes in a mold is liable to occur.

(Closed cell rate) The closed cell rate of the crushed granules of the present invention is preferably 50 to 100%, and is preferably 60 to 10%.
More preferably, it is 0%. The closed cell rate can be appropriately adjusted by changing the water retention of the crushed particles. For example, when the water retention of the crushed particles is 0.04 to 0.10. The closed cell rate is in the range of about 50 to 100%. The measurement of the closed cell rate is performed according to ASTM D-2856 (Standard Method fo).
r MEASURING THE OPEN CELL CONTENT OF RIGID CELLULA
R PLASTICS BY THE AIR PYCNOMETER). Apparatus: Air comparison specific gravity meter 930 type [manufactured by Toshiba Beckman Co., Ltd.] Method: 1-1 / 2-1 atmospheric pressure method Test piece: foamed particles 0.50 g (apparent volume is measured by Archimedes method)

(Water Retention) The high water retentivity of the crushed granules indicates that the closed cell ratio of the crushed granules is high. When the foamed particles are broken or the closed cell structure is broken, a non-closed cell structure, that is, a shape (sponge-like) having an open cell structure is obtained, and water retention is increased. Therefore, the lower the water retention, the higher the closed cell rate. The water retention of the crushed granules of the present invention is 0.04 to 0.10.
0.08 is more preferred. If the water retention exceeds 0.10, the closed cell ratio of the crushed particles becomes low, and it is difficult to obtain a good mixed molded product. Although the water retention rate may be 0.04 even when the closed cell rate is 100%, this is considered to be residual intergranular water.

The crushed granules having a water retention of 0.04 to 0.10 can be mixed with the pre-expanded particles at a volume ratio of 10 to 60% to form a favorable mixed molded article. In addition,
In the measurement of the water retention, first, the weight (dry sample weight) and the bulk factor of 3 g of the crushed granules obtained by classifying the minor axis length into 2 to 5 mm and arranging them are measured. The crushed granules are packed in a non-woven cloth or net for draining with an opening of 1 mm or less, and 15 cm below the water surface
And left for 24 hours. Next, the crushed particles are placed on a wire mesh having an opening of 0.5 to 1.5 mm square, the wire mesh is tilted at 30 degrees and left for 30 seconds, and then the weight of the crushed particles (weight of a water-absorbing sample) is measured. The water retention rate is calculated by substituting the weight and bulk factor of the crushed particles measured first and the weight of the crushed particles after water absorption into the following formula.

[0025] The draining bag is made of a nonwoven fabric manufactured by Nippon Sunpac Co., Ltd. and a triangular corner draining bag made of polyethylene (270 × 250 mm) used in the examples described later. , PP, PET, or a non-woven fabric or net.

(Foaming ability of crushed grains) The foaming ability of crushed grains in the present invention is measured by immersing the crushed grains in a large amount of boiling water and heating them in the same manner as in the measurement of the foaming ability described above. The maximum foaming ability of the crushed granules thus obtained is 1.2 to 1.6, and more preferably 1.3 to 1.6. If the maximum foaming capacity of the crushed particles is less than 1.2, the crushed particles are crushed by the pre-expanded particles during foam molding, and the strength of the mixed molded product is extremely reduced. Conversely, if the maximum foaming ability exceeds 1.6, voids formed by shattering of crushed particles are likely to be generated inside the mixed molded product.

(Crushed particle mixed molded article) The crushed particle mixed molded article of the present invention is obtained by mixing crushed particles and pre-expanded particles obtained by expanding expandable styrene resin particles to a predetermined bulk multiple. It can be manufactured by in-mold foam molding. The ratio of the crushed particles in the mixed particles is preferably about 10 to 60% by volume, more preferably about 20 to 50%. In the conventional crushed granules obtained by crushing the conventional foam molded product having a high fusion rate, the mixing ratio is limited to 20% by volume, and if the mixing ratio is higher, the physical strength of the mixed molded product is extremely high. Drop,
The appearance of the molded article also tended to be significantly reduced. The reason why the physical strength of the mixed molded article is reduced is that the foaming power of the pre-expanded particles is strong, whereas the foaming ability of the crushed particles is weak, so that the crushed particles are crushed into a shrunk shape. In addition, it is considered that the pre-expanded particles are excessively expanded, partially become highly expanded, and the strength of the whole mixed molded article is reduced.

(Maximum Foaming Ability of Pre-Expanded Particles Used in Mixed Molded Article) To obtain a better secondary molded article,
The maximum foaming capacity of the pre-expanded particles also needs to be adjusted. If the maximum foaming capacity of the pre-expanded particles is too high, even if the closed cell ratio of the crushed particles is high, the crushed particles are crushed by the pre-expanded particles, and the pre-expanded particles are excessively foamed by that much, so that the High foaming results in a decrease in the strength of the entire secondary molded body. As a solution to this, in the present invention, the difference between the foaming ability when the crushed expanded styrene resin particles are heated and the maximum foaming ability of the pre-expanded particles is the same under the same heating conditions as the pre-expanded particles exhibit the maximum foaming ability. When it is 1.0 or less, a good secondary molded body with little deterioration in physical properties can be obtained. Therefore, the maximum foaming ability of the pre-expanded particles used in the mixed molded product is preferably about 1.4 to 2.1. The fusion ratio of the mixed molded product obtained by molding the mixed particles is 60%.
By adjusting below, the mixed molded product can be further reused.

[0029]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[Examples 1 to 3, Comparative Examples 1 and 2] [Production of expandable styrene resin particles] [Synthesis Example 1] In a polymerization tank having an internal volume of 100 liters and provided with a stirrer, 40.0 liters of water were added. 100 g of magnesium pyrophosphate and 1.8 g of sodium dodecylbenzenesulfonate were added, and then 40.0 kg of styrene, 96.0 g of benzoyl peroxide and 29.0 g of t-butylperoxybenzoate were added, and 90 g of the mixture was stirred.
The temperature was raised to ° C. to obtain the polymerization temperature. Next, the temperature was maintained at this temperature for 6 hours, and after further raising the temperature to 125 ° C., 2 hours later, cooling was performed to obtain styrene resin particles. The obtained resin particles were classified to obtain styrene resin particles of 1.0 to 1.2 mm. Next, 1800 g of the styrene resin particles obtained above and 2200 water were placed in a polymerization tank having an internal volume of 5 liters and equipped with a stirrer.
g, 6.0 g of magnesium pyrophosphate, 0.3 g of sodium dodecylbenzenesulfonate, and 18 g of toluene. The mixture was heated to 90 ° C. while stirring, and then n-butane 18 was added.
0 g (10% use rate) was injected and held for 5 hours. Next, the mixture was cooled to 30 ° C. or lower to obtain expandable styrene resin particles. The extracted expandable styrene resin particles were dried and aged in a thermostatic chamber at 15 ° C. for 5 days.

[Synthesis Example 2] 144 g of butane was used
(Utilization rate: 8%), except that foamable styrene resin particles were obtained in the same manner as above. [Synthesis Example 3] Expandable styrene resin particles were obtained in the same manner as described above except that the amount of butane used was changed to 54 g (3% use rate). [Synthesis Example 4] The amount of butane used was 108 g (use rate 6%)
Was obtained in the same manner as described above, except that styrene-based resin particles were obtained.

[Prefoaming and Measurement of Foaming Ability of Prefoamed Particles] Into a batch foaming machine having an internal volume of 33 L (effective volume 25 L), 500 g each of the expandable styrene resin particles obtained in Synthesis Examples 1 to 3 were charged. Then, the injected steam at a steam temperature of 99 ° C. was injected at a pressure of 0.05 kgf / cm ² , and the pressure was adjusted as shown in Table 1.
The following pre-expanded particles were obtained. Similarly, 830 g of expandable styrene-based resin particles were added to obtain pre-expanded particles which were expanded 30 times. After each of the obtained pre-expanded particles was aged for 1 day, the maximum foaming ability was measured by the following method.

[0033]

[Table 1]

[Measurement of foaming capacity and maximum foaming capacity] The foaming capacity is measured by measuring the bulk multiple of the pre-expanded particles in advance, and using the pre-expanded particles as a wire mesh having a capacity of 1 liter and an opening of 1 mm, for example. Put in a basket with a lid and make a lid.
Next, water having a capacity of 10 liters or more is put into a cylindrical container having a diameter of 20 cm, and heated by an electric heater of 1 kilowatt in the atmosphere to boil. Next, the basket container containing the pre-expanded particles is quickly submerged in boiling water while being heated and boiled, and after being heated and foamed for a predetermined time, the basket container is quickly taken out. After being taken out, it is left at room temperature for 3 hours, and then the bulk multiple of the expanded particles is measured. The value obtained by dividing the bulk multiple of the expanded beads heated in the boiling water by the bulk multiple of the pre-expanded particles before heating was defined as the expansion capacity. This operation was repeated every predetermined time, and the value at each time was determined, and the highest value was defined as the maximum foaming ability.

Each of the pre-expanded particles obtained on the [expanded molded article] is converted into an ACE-3SP molding machine [Sekisui Koki Co., Ltd.]
(Mold size: 300 × 400 × 100mm)
And foamed under the following molding conditions. Steam forming pressure See Table 2 Mold heating time 8 seconds On the other hand heating time 15 seconds Double-sided heating time 15 seconds Water cooling time 30 seconds Each of the obtained foamed moldings has a foaming multiple of 50 times, and other physical properties (maximum foaming capacity) , Fusion rate, bending strength, bending strength reduction rate, compression strength and compression strength reduction rate)
Are shown in Table 2. In addition, the bending strength reduction rate and the compression strength reduction rate are determined by setting the bending strength and the compression strength of the foamed molded article to 100%.
The calculated value was expressed in%. As for the appearance of the foamed molded article, the elongation of the foamed surface particles was insufficient, but the appearance of the other molded articles was good.

[0036]

[Table 2]

Example 4 The above-mentioned pre-expanded particles (maximum foaming capacity: 1.4) were subjected to foam molding under the same conditions as in Example 2 to obtain a foam molded article having a foaming factor of 30 times. The foam molding has a fusion rate of 10% and a flexural strength of 3.7 kgf.
/ Cm ² , and the compressive strength was 1.90 kgf / cm ² . In addition, the measuring method of bending strength and compressive strength is as follows. [Measurement of bending strength] This was performed according to JIS-9511. The test sample is placed on a support and the center between the fulcrums is
A load was applied at a load speed of mm, the maximum load was measured, and substituted into a calculation formula to determine the bending strength (kgf / cm ² ).

[Measurement of Compressive Strength] Measured according to JIS-9511. That is, the test sample is compressed at a rate of 10 mm per minute, and the stress (kgf / c) when a compressive strain of 5% occurs.
m ² ) was determined.

[Examples 5 to 9 and Comparative Examples 3 and 4] [Crushing and Mixing Molding] The above foamed molded article and the above foamed article were crushed using an impact crusher used for recycling of foamed plastic. did. Crushing was performed in two stages, coarse crushing and fine crushing. Coarse crushing is performed by a shear crusher [trade name: FSC-310, manufactured by Nao Corporation].
And crushed to 40 mm. The fine crushing was performed using an impact crusher [trade name: MC-1 manufactured by Nano Corporation]. The obtained crushed granules were classified with a sieve at an upper limit of 7 mm and a lower limit of 2 mm. The yield of the classified crushed granules was 75% by weight in the crushed granules, and many fine particles of 2 mm or less were generated, whereas 89% of the crushed granules, 96% of the crushed granules, and 93% of the crushed granules. It was confirmed that generation of fine particles of 2 mm or less was small. Therefore,
The crushed granules according to the present invention obtained by crushing a foam molded article having a low fusion rate are easily crushed and generate few fine particles. Next, in order to keep the residual gas amount of the obtained crushed particles to constant, it was left in a constant temperature bath at 40 ° C. for 7 days.

[0040]

[Table 3]

Each of the crushed particles shown in Table 3 and the pre-expanded particles shown in Table 1 were uniformly mixed at a mixing ratio shown in Table 4, and the steam forming pressure was set to 0.7 kgf / cm ^2. Was subjected to foam molding in the same manner as the molding of the foam molded article.

[0042]

[Table 4]

The bending strength, the reduction rate of the bending strength, the compression strength, the reduction rate of the compression strength and the fusion rate of the obtained crushed and mixed granules were measured. Table 4 shows the results.
In addition, the bending density reduction rate and the compression strength reduction rate are represented by%, with the bending strength and the compression strength of the foamed molded article taken as 100. In addition, even if the mixed particles are subjected to foam molding, the physical properties of the secondary molded body are not significantly reduced. Therefore, the mixing ratio of the crushed particles can be increased as compared with the conventional case.

Example 7 The crushed particles shown in Table 3 and the pre-expanded particles shown in Table 1 were uniformly mixed at a volume ratio of 70% and 30%, and foamed in the same manner as described above. The bending strength of the obtained crushed grain mixed molded product was 3.26 kgf / cm ² , and the fusion rate was 50%. When the pre-expanded particles were heated under the same conditions as the heating time of 60 seconds in boiling water showing the maximum foaming ability, the foaming ability of the crushed granules was 1.04, and the difference in the foaming ability was 0.56. .

[0045]

The foam molded article of the present invention can be easily crushed by a crusher since the physical strength is hardly reduced and the fusion ratio is 0 to 60%. Further, since the closed cells structure is sufficiently maintained in the crushed granules according to the present invention,
By mixing with the pre-expanded particles and subjecting to foam molding, a high-quality foam molded article can be obtained. In addition, since the mixing ratio of the crushed particles can be increased, the foam molded article can be efficiently recycled.

Claims (8)

[Claims] 1. The method according to claim 1, wherein the expandable styrene resin particles have a bulk factor of 20.
The maximum foaming ability obtained by foaming up to 70 times is 1.2 to
2.0 pre-expanded particles are obtained by foam molding.
A foamed styrene-based resin molded product having a fusion rate of 0 to 60%. 2. The maximum foaming ability obtained by crushing the foamed styrenic resin molded product according to claim 1 is 1.2 to 1.6.
Styrene resin crushed particles. 3. The water retention rate per unit volume is from 0.04 to
The styrene resin foam crushed particles according to claim 2, wherein the particle diameter is 0.10. 4. The crushed styrene resin particles according to claim 2, wherein the closed cell ratio is 50 to 100%. 5. The length of the minor axis is 2 to 7 mm.
5. The crushed granules of expanded styrene resin according to any one of items 4 to 4. 6. The expanded styrene obtained by mixing the crushed expanded styrene resin particles according to claim 2 and pre-expanded particles obtained by expanding the expandable styrene resin particles. 10-60% by volume of crushed resin particles
A foamed styrene-based resin crushed particle mixed molded product obtained by subjecting the mixed particles to foam molding. 7. The maximum foaming ability of the pre-expanded particles is from 1.4 to 1.4.
The foamed styrene-based resin crushed particle mixed molded article according to claim 6, which is 2.1. 8. The difference between the foaming capacity when the crushed styrene resin particles are heated and the maximum foaming capacity of the pre-expanded particles is 1.0 or less under the same heating conditions as those under which the pre-expanded particles exhibit the maximum foaming ability. The foamed styrene-based resin crushed granule mixed molded product according to claim 6 or 7.