JPH08100078A - Foamable resin particle, prefoamed resin particle therefrom, and production of molded foam - Google Patents

Abstract

PURPOSE: To obtain foamable resin particles from which a foam comprising a blend of a styrene resin with a poly(phenylene ether) resin as a base resin can be molded at a low steam pressure. CONSTITUTION: Base resin comprising 50-85 pts.wt. styrene resin and 50-15 pts.wt. poly(phenylene ether) resin in an amount of 100 pts.wt. is mixed with 1-9 pts.wt. organic solvent having a KB value of 20-200 and a boiling point of 95-400 deg.C and 1-10 pts.wt. readily volatile foaming agent. Ordinary machines for the prefoaming and foam molding of styrene resins can be used as such to foam and mold the mixture. Thus, a molded foam having high mechanical strength can easily be produced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a foamable resin particle capable of pre-foaming a foam having a mixed resin composed of a styrene resin and a polyphenylene ether resin as a base resin at a low molding vapor pressure. The present invention also relates to a pre-expanded resin particle thereof and a method for producing an expanded molded article thereof.

[0002]

2. Description of the Related Art Expanded polystyrene obtained by foaming a polystyrene resin has been widely used as a cushioning material and a structural material because it is particularly lightweight, has high mechanical strength and is excellent in cushioning properties. For the purpose of further improving the mechanical strength of the polystyrene foam, a polyphenylene ether resin is mixed with or copolymerized with the polystyrene resin (for example, JP-A-52). -101267 gazette etc.).

[0003]

As described above, the mechanical strength is further improved by changing a part of the styrene resin to the polyphenylene ether resin, and the same strength can be exhibited with less material. On the other hand, advantages are obtained, but a high vapor pressure is required to foam-mold these mixed or copolymerized resins, and the gauge pressure, which is the pre-foaming pressure of conventional polystyrene resins, is 0 to 0.2 kg / cm.
^2. There was a defect that molding could not be performed with a low molding pressure of 1.3 kg / cm ² or less, which is a foam molding pressure.
Therefore, it is necessary to prepare a special pre-foaming machine and foam molding machine, and it is not possible to foam-mold with the conventionally used pre-foaming machine and foam-molding machine, or even if it can, foam-mold up to a high magnification. I couldn't do that.

The present invention has been made in view of the above circumstances, and an object thereof is to conventionally use a foamed molded product having a base resin of a mixed resin composed of a styrene resin and a polyphenylene ether resin. An object of the present invention is to provide an expandable resin particle that can be foam-molded using the pre-foaming machine and the foam molding machine, a pre-foamed resin particle thereof, and a method for producing the foam molded article.

[0005]

In order to solve the above problems, the present invention relates to 100 parts by weight of a resin containing 50 to 85 parts by weight of a styrene resin and 50 to 15 parts by weight of a polyphenylene ether resin. A foamable resin particle containing 1 to 9 parts by weight of an organic solvent having a KB value of 20 to 200 and a boiling point of 95 to 400 ° C. and 1 to 10 parts by weight of a volatile foaming agent, and Disclosed are pre-expanded resin particles obtained by pre-expanding expandable resin particles to a bulk ratio of 5 to 50 times.

The present invention further includes styrenic resins 50-8.
A KB value of 20 to 20 is added to 100 parts by weight of a resin containing 5 parts by weight and 50 to 15 parts by weight of a polyphenylene ether resin.
An organic solvent having a boiling point of 95 to 400 ° C. and an easily volatile foaming agent was melted, mixed and extruded, and immediately thereafter, the expandable resin particles obtained by rapid cooling were heated to give a gauge pressure of 0.2 kg.
/ Cm ² was pre-expanded with vapor pressure below also discloses a method for producing a foamed molded, characterized in that hot forming under a gauge pressure of 1.3 kg / cm ² or less vapor pressure.

The contents of the present invention will be described in more detail below. The styrene resin referred to in the present invention is not limited to a homopolymer of a styrene monomer, but includes a copolymer. The styrene-based monomer includes methylstyrene, ethylstyrene and the like in addition to styrene. Further, the copolymer contains a copolymer containing 50% or more of styrene monomer. Examples of the partner monomer of the copolymer include methacrylic acid esters such as methyl methacrylate, acrylic acid esters, acrylic acid, methacrylic acid, acrylonitrile, and maleic anhydride. These may be used alone,
Two or more kinds may be used in combination.

The polyphenylene ether resins used in the present invention include, for example, poly (2,6-dimethylphenylene-1,4-ether), poly (2-methyl-6-ethylphenylene-1,4). -Ether), poly (2,6-
Diethylfinylene-1,4-ether), poly (2-
Methyl-6-n-propylphenylene-1,4-ether), poly (2-methyl-6-n-butylphenylene-)
1,4-ether), poly (2-methyl-6-chlorophenylene-1,4-ether), poly (2-methyl-6)
-Bromphenylene-1,4-ether), poly (2-
Methyl-6-bromophenylene-1,4-ether) and the like.

The base resin used in the present invention may contain a flame retardant, a stabilizer, a cell regulator, a coloring agent, an ultraviolet absorber, etc., if necessary. The component of the base resin is a ratio of 50 to 85 parts by weight of styrene resin and 50 to 15 parts by weight of polyphenylene ether resin, preferably 60 to 80 parts by weight of styrene resin and 40 to 20 parts by weight of polyphenylene ether resin. . When the proportion of the polyphenylene ether resin is less than 15 parts by weight, the desired mechanical strength cannot be obtained, and when it is 50 parts by weight or more, the moldability is deteriorated and a good quality foam molded article cannot be obtained.

The organic solvent used in the present invention has a KB value (that is, a kauributanol value according to the measuring method shown in ASTM-D-1133-61) of 20 to 200, preferably 30 to 150, and a boiling point. 95-400 at normal pressure
C., preferably 99 to 350.degree. C. is used. This organic solvent promotes plasticization of the base resin and exhibits good foamability even at a low pressure, whereby the moldability of the resin is improved.

When the KB value is less than 20, the base resin cannot be sufficiently plasticized and improvement in moldability cannot be expected. When the KB value is 200 or more, the base resin is excessively plasticized and pre-foaming or foam molding is performed. Immediately afterwards it causes significant contraction. Further, when the boiling point of the organic solvent is less than 95 ° C, the effect as a foaming agent becomes remarkable and the effect for plasticizing is deteriorated, which is not preferable, and when the boiling point is 400 ° C or more, it is a base material. Since the resin is too plasticized, the shrinkage immediately after foaming becomes remarkable, which is not preferable.

The organic solvent is contained in the base resin in an amount of 1 to 9 parts by weight, preferably 3 to 6 parts by weight. When it is less than 1 part by weight, the plasticization of the base resin becomes insufficient, and when it is 9 parts by weight or more, the base resin is excessively plasticized and the shrinkage immediately after foaming is remarkable, and a stable molded product can be obtained. Disappear. Specifically, aromatic hydrocarbons such as toluene, benzene, xylene, and ethylbenzene, chlorobenzene,
Halogenated aromatic hydrocarbons such as bromobenzene and dichlorobenzene, n-heptane, n-octane, i-octane, n-decane, n-dodecane, n-paraffin,
Alkanes such as i-paraffin, n-butanol, 2
-Alcohols such as ethylhexanol and octanol. These may be used alone or in combination of two or more.

As the volatile foaming agent used in the present invention,
About 5 even with low-pressure steam with a gauge pressure of 1.3 kg / cm ² or less
For highly foam-molding up to 0 times, an organic compound that has a boiling point not higher than the softening point of the styrene resin and is gaseous or liquid at normal pressure is suitable. Propane, butane, pentane, cyclopentane, cyclopentadiene Hydrocarbons such as petroleum ether, halogenated hydrocarbons such as ethyl chloride, chlorodifluoroethane, 1-fluoro-2-trifluoroethane and difluoroethane, and low boiling point ether compounds such as dimethyl ether and dipropyl ether are used. These may be used alone or in combination of two or more.

The blowing agent is contained in the base resin in an amount of 1 to 10 parts by weight, preferably 2 to 8 parts by weight. If it is less than 1 part by weight, it is impossible to foam to the desired high magnification, and if it is 10 parts by weight or more, it is difficult to uniformly disperse the foaming agent in the base resin, and a good foam is obtained. I can't. The base resin is blended as described above, and the organic solvent and the volatile foaming agent are melted and kneaded in the extruder at the above ratio, and extruded in a strand form from the nozzle of the die tip of the extruder, and the water tank. After being rapidly cooled and dried, it is cut into pellets of a predetermined size to obtain expandable resin particles. As described above, the base resin can be blended in an arbitrary ratio in one step, and at the same time, the expandable resin particles containing the organic solvent and the volatile foaming agent and having a particle size suitable for foam molding can be obtained. 2.5 to 3.5, which is the size of resin pellets commonly used in the process
A base resin having the above-mentioned composition is pelletized into pellets of a predetermined size smaller than mm, and the organic solvent and the volatile foaming agent are impregnated in the following step by an autoclave or the like to form a foamable resin. The foamable resin can be efficiently produced in a smaller number of steps as compared with the method which requires two steps of obtaining particles.

The size of the expandable resin particles obtained is not particularly limited, but the equivalent spherical diameter defined below is 0.3 to 2.0.
Those having a size of mm are particularly preferable because they can be easily molded into a foaming ratio of 5 to 50 times. Here, the sphere-converted diameter means that the cut expandable resin particles and pellets before impregnation have a cylindrical shape,
The cylinder is assumed to be a sphere and is calculated by the following formula. That is, assuming that the volume S of the cylinder is the diameter D of the cylinder and the length L,
πL (D / 2) ² Volume of sphere V: (4/3) π (d
Since / 2) ³ S = V: πL (D / 2) ² = (4/3) π (d /
2) ³ Therefore, in terms of sphere diameter is calculated as ³ √ (3LD ^2/2).

According to the experiments conducted by the present inventors, the expandable resin particles thus obtained have a gauge pressure of 0 which is a pre-expanding pressure used in a conventional pre-expanding machine for polystyrene.
Bulk ratio of 5 to 5 with water vapor pressure of ~ 0.2 kg / cm ^2.
It was confirmed that pre-foaming could be easily performed up to about 0 times. Therefore, it is unnecessary to prepare a special device for pre-expanding the expandable resin particles, and the pre-expanding resin particles can be obtained by using the pre-expanding machine which has been used conventionally.

The pre-expanded resin particles obtained are aged for a predetermined time and then foam-molded to obtain a molded product. According to the experiments conducted by the present inventors, the obtained pre-expanded resin particles have a gauge pressure of 0 to 1.3 kg, which is the foaming molding pressure of conventional polystyrene.
Can be easily foam-molded to a molded product magnification of about 5 to 50 times with a low water vapor pressure of / cm ² , and
It was confirmed that the obtained molded product had a good appearance and the internal fusion rate was 80% or more. Therefore, it is not necessary to prepare a special molding device for foam molding of the molded product using the pre-expanded resin particles, and the foam molded product for polystyrene is used as it is. Can be obtained.

[0018]

The present invention will be described below with reference to examples. In the following, the internal fusion rate is a value calculated by the following equation from the fractured state of the fracture surface when the molded body is fractured. Internal fusion rate (%) = [(total area of fracture surface)-(area fractured from particle-particle interface at fracture surface)) / (total area of fracture surface) x 100 Also, drop strength is a strength property of the molded product. The impact value was evaluated.
That is, the test was conducted by the following method, and the height (H50) at which 50% of the sample was destroyed was taken as the falling ball impact value.

A 40 × 215 × 15 mm sample was prepared from a 1.300 × 400 × 15 mm plate-shaped molded product. 2. Both ends of the sample were gripped with a span of 160 mm, the height was changed, and a 321 g steel ball was dropped to the center of the span. Steel balls were dropped on five samples at the same height.

Tests were carried out by changing the height at intervals of 2.5 cm from the maximum height at which all 3.5 samples were not destroyed to the minimum height at which all were destroyed, and the falling ball impact value was calculated from the following formula. did. H50 = HL-ΔH × (S / 100-1 / 2) H50: 50% fracture height of sample (falling ball impact value: c
m) HL: Minimum height (cm) when the sample is 100% destroyed ΔH: Interval (cm) for changing height (ΔH = 2.5c
m) S: Total of% broken at each height below HL.

Example 1 Polyphenylene ether (hereinafter referred to as PPE) and polystyrene (hereinafter referred to as PS) were used as main raw materials, and talc 0.1 was used as a bubble control agent.
Add parts by weight, mix so as to be PPE / PS = 33/67, and use pentane as a foaming agent and ethylbenzene (KB value 99, boiling point 136 ° C.) as an organic solvent, melt and knead with an extruder, It was extruded in a strand form from a nozzle die provided at the tip of the die, rapidly cooled in a water tank, dried, and then cut by a rotary pelletizer to be pelletized. Then, the mixture was aged for 5 days, and had a spherical equivalent diameter of 0.9 including 4.5 parts by weight of pentane and 3.2 parts by weight of ethylbenzene.
9 mm of expandable resin particles were obtained.

The expandable resin particles thus obtained were heated for 2 minutes at a steam pressure of 0.1 kg / cm ² using a pre-expanding machine to foam, and a bulk ratio of 13 times, pentane 3.3 parts by weight, ethylbenzene. 2.1 parts by weight of pre-expanded resin particles were obtained. After aging the pre-expanded resin particles for 24 hours, a gauge pressure of 1.0 was obtained using a foam molding machine for polystyrene molding.
It was heated with steam of kg / cm ² for 60 seconds to obtain a 300 × 400 × 15 mm plate-shaped foam-molded article having a molded article magnification of 13 times. The molded product had a good appearance and the internal fusion rate was 90%. In addition, the falling ball impact value was measured as the strength measurement of this molded product. The result was 86 cm

[Example 2] PPE / PS = 25/75 was blended, pelletized under the same conditions as in Example 1, and the spherical equivalent diameter containing 5.3 parts by weight of pentane and 3.1 parts by weight of ethylbenzene. 0.98 mm expandable resin particles were obtained. When the expandable resin particles obtained were expanded under the same conditions as in Example 1, pre-expanded resin particles containing 4.1 parts by weight of pentane and 2.5 parts by weight of ethylbenzene were obtained with a bulk ratio of 16 times. The pre-expanded resin particles were foam-molded under the same conditions as in Example 1 to obtain a foam-molded product having a molded product ratio of 16 times, good appearance, and an internal fusion rate of 95%. The falling ball impact value of this molded product was 61 cm.

Example 3 PPE / PS = 30/70 was blended, to which 0.1 part by weight of talc was added as a cell adjuster, pentane as a foaming agent, and n-paraffin (as an organic solvent). (KB value 25, boiling point 200 ° C.), pelletized in the same manner as in Example 1 and aged for 3 days to contain 4.8 parts by weight of pentane and 3.3 parts by weight of n-paraffin, and a spherical equivalent diameter of 1.0 mm. Thus, expandable resin particles were obtained.

The expandable resin particles obtained were expanded under the same conditions as in Example 1 to obtain pre-expanded resin particles containing 12 times the bulk ratio, 3.8 parts by weight of pentane and 2.3 parts by weight of n-paraffin. Was given. The pre-expanded resin particles were foam-molded under the same conditions as in Example 1 to obtain a foam-molded product having a molded product magnification of 12 times and an internal fusion ratio of 90% with a good appearance.

[Example 4] PPE / PS was blended so as to be 20/80, pelletized under the same conditions as in Example 3, and a spherical equivalent diameter containing 4.3 parts by weight of pentane and 4.3 parts by weight of toluene. 1.0 mm of expandable resin particles were obtained. The expandable resin particles obtained were expanded under the same conditions as in Example 1,
Bulk ratio 30 times, pentane 3.3 parts by weight, toluene 3.0
Pre-expanded resin particles including parts by weight were obtained. When the pre-expanded resin particles were foam-molded under the same conditions as in Example 1, a foam-molded product having a molded product ratio of 30 times, good appearance, and an internal fusion rate of 80% was obtained.

[Comparative Example 1] PPE / PS was blended so as to be 24/76 and pelletized under the same conditions as in Example 1 except that ethylbenzene was not used, and the spherical equivalent diameter 1 containing 4.5 parts by weight of pentane. Foamable resin particles of 0.02 mm were obtained. The expandable resin particles obtained were foamed under the same conditions as in Example 1, but the bulk magnification was up to 3 times. The obtained pre-foamed resin particles contained 4.0 parts by weight of pentane. The pre-expanded resin particles were foam-molded under the same conditions as in Example 1, but the internal fusion rate was extremely low and they easily separated, so that a molded product could not be obtained.

[Comparative Example 2] PPE in the same proportion as in Example 1
/ PS is blended, pentane is used as a foaming agent, and toluene is used as an organic solvent to form a pellet, and a spherical equivalent diameter of 0.99 m containing 6.3 parts by weight of pentane and 0.6 parts by weight of toluene.
m expandable resin particles were obtained. The expandable resin particles obtained were expanded under the same conditions as in Example 1, but they could only be expanded up to a bulk ratio of 4 times. The pre-expanded particles contained 4.0 parts by weight of pentane and 0.4 parts by weight of toluene. The pre-expanded resin particles were foam-molded under the same conditions as in Example 1, but the molded product had a low magnification of 4 and the appearance was poor.
Only a foam-molded product having an internal fusion rate of 10% was obtained.

[Comparative Example 3] PPE in the same proportion as in Example 1
/ PS was blended, pentane was used as a foaming agent, and toluene was used as an organic solvent, and pelletized to obtain 4.2 parts by weight of pentane and 9.8 parts by weight of toluene to obtain expandable resin particles.
The expandable resin particles obtained were expanded under the same conditions as in Example 1, but a significant shrinkage occurred immediately after pre-expansion, and good pre-expanded resin particles could not be obtained.

[Comparative Example 4] The same procedure as in Example 1 was carried out except that only polystyrene was used as the main raw material, and 4.5 parts by weight of pentane and 3.2 parts by weight of ethylbenzene were used. The expandable resin particle which is 0.99 mm was obtained. The obtained expanded resin particles were pre-expanded under the same conditions as in Example 1 to obtain a bulk ratio of 16 times, pentane of 3.0 parts by weight,
Pre-expanded particles of 2.0 parts by weight of ethylbenzene were obtained.

The pre-expanded particles were foam-molded under the same conditions as in Example 1 to obtain a plate-shaped molded product having a molded product ratio of 16 times. The molded product had a good appearance and an internal fusion rate of 90%. When the falling ball impact value of this molded product was measured, it was as low as 35 cm, and the falling ball impact value was about half that of the molded product obtained in Example 2 having the same molded product magnification.

[0032]

EFFECTS OF THE INVENTION According to the present invention, a conventional polystyrene foam prefoaming machine and a foam molding machine are used as they are, and a mechanical resin having a mixed resin composed of a styrene resin and a polyphenylene ether resin as a base resin is used. It is possible to easily form a foam-molded article having high strength.

Claims (3)

[Claims] 1. An organic solvent having a KB value of 20 to 200 and a boiling point of 95 to 400 ° C. with respect to 100 parts by weight of a resin containing 50 to 85 parts by weight of a styrene resin and 50 to 15 parts by weight of a polyphenylene ether resin. 1 to 9 parts by weight and an easily volatile foaming agent 1 to 10 parts by weight, expandable resin particles. 2. An organic solvent having a KB value of 20 to 200 and a boiling point of 95 to 400 ° C. with respect to 100 parts by weight of a resin containing 50 to 85 parts by weight of a styrene resin and 50 to 15 parts by weight of a polyphenylene ether resin. Pre-expanded resin particles obtained by pre-expanding expandable resin particles containing 1 to 9 parts by weight and 1 to 10 parts by weight of a volatile foaming agent to a bulk ratio of 5 to 50 times. 3. 100 parts by weight of a resin containing 50 to 85 parts by weight of a styrene resin and 50 to 15 parts by weight of a polyphenylene ether resin, a KB value of 20 to 200 and a boiling point of 95.
Melting an organic solvent that is ~ 400 ° C and a volatile foaming agent,
Immediately after mixing and extruding, the expandable resin particles obtained by rapid cooling were heated to prefoam at a vapor pressure of 0.2 kg / cm ² or less and then a gauge pressure of 1.3 kg / cm ^2.
A method for producing a foam-molded article, which comprises heat-molding at the following vapor pressure.