JP6322999B2 - Foam molding - Google Patents

Description

  The present invention relates to a foam-molded product obtained by fusing polystyrene-based resin foam particles to each other.

  A foam-molded product obtained by fusing polystyrene-based resin expanded particles with each other is lightweight and excellent in heat insulation. For this reason, the foam molded body is used for a building heat insulating material or a cold box. In addition, foamed molded products are also used in applications that require air permeability, water permeability, and sound absorption. In such an application, a foamed molded article having continuous voids connecting the expanded particles and having a high porosity is used (see Patent Documents 1 to 5). In addition, composites have been developed in which the voids of the foamed molded article having such voids are impregnated with a thermosetting resin raw material or gypsum and solidified.

  A foamed molded product having a high porosity is produced as follows. Specifically, first, a plurality of expanded particles are filled into a mold. Next, steam is supplied into the mold. Thereby, the foamed particles are fused to each other. Next, the foamed molded body is obtained by cooling the inside of the mold by water cooling or the like.

Japanese Patent Laid-Open No. 5-200892 JP 2006-110982 A JP 2007-106973 A Japanese Patent No. 3268094 Japanese Patent No. 329311

  However, in the conventional foamed molded article having voids, the fusion force between the foamed particles is still insufficient. For this reason, the foamed particles constituting the foamed molded product are easily dropped from the foamed molded product. Further, such a foamed molded article has low bending strength, bending elastic modulus, bending deflection and the like, and has insufficient bending characteristics. In particular, when the porosity of the foamed molded product is increased, the bending characteristics tend to deteriorate.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a foamed molded article having both high porosity and excellent bending characteristics.

One aspect of the present invention is a foamed molded article comprising a large number of polystyrene resin foam particles fused together, and having continuous voids connecting the polystyrene resin foam particles,
The polystyrene resin foam particles constituting the foamed molded article have a surface melt layer formed on the surface by melting the surface layer of the polystyrene resin foam particles,
The foamed molded article has a connecting portion that connects the polystyrene resin foam particles to each other, wherein the surface melt layer is stretched after adjacent polystyrene resin foam particles are fused to each other. ,
The apparent density of the foamed molded product is 9-30 kg / m ³ ,
The foamed molded product is characterized by having a porosity of 5 to 65% by volume.

  The foamed molded product has continuous voids between the expanded particles, and has a high porosity as described above. And the expanded particle which comprises a foaming molding has the said surface melt layer, and a foaming molding has a connection part extended after the surface melt layer of a foaming particle fuse | melts mutually. Yes. Therefore, in the said foaming molding, while it becomes possible to make a porosity high, a foaming molding combines a high porosity and the outstanding bending characteristic. Moreover, it becomes difficult for the foamed particles to fall off the foamed molded article.

Explanatory drawing which shows the external appearance of the foaming molding in an Example. The photograph substitute figure which shows the digital photograph of the surface of a foaming molding in an Example. The photograph substitute figure which shows the digital photograph in the cross section of the foaming molding in an Example. The photograph substitute figure which shows the scanning electron micrograph of the surface of the foaming molding in an Example. The photograph substitute figure which shows the scanning electron micrograph of the cross section of the foaming molding in an Example. The photograph substitute figure which shows the digital photograph of the surface of the foaming molding in a comparative example. The photograph substitute figure which shows the digital photograph in the cross section of the foaming molding in a comparative example. The photograph substitute figure which shows the scanning electron micrograph of the surface of the foaming molding in a comparative example. The photograph substitute figure which shows the scanning electron micrograph of the cross section of the foaming molding in a comparative example.

Next, a preferred embodiment of the foamed molded product will be described.
The foamed molded article is composed of a large number of polystyrene resin foam particles fused to each other. In the present specification, the polystyrene resin refers to a resin having a styrene monomer component unit of 50% by mass or more. That is, the polystyrene resin can be copolymerized with not only a homopolymer of a styrene monomer but also a copolymer of two or more styrene monomers as well as one or more styrene monomers. It is a concept including a copolymer with a vinyl monomer. The styrene monomer component unit in the polystyrene resin is preferably 80% by mass or more, and more preferably 90% by mass or more.

  Examples of the styrene monomer include styrene, α-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-ethyl styrene, 2,4-dimethyl styrene, p-methoxy styrene, p- n-butylstyrene, pt-butylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,4,6-tribromostyrene, divinylbenzene, styrenesulfonic acid, sodium styrenesulfonate, etc. Can be mentioned. These may be used alone or in combination of two or more.

Other vinyl monomers that can be copolymerized with styrene monomers include acrylic acid esters, methacrylic acid esters, vinyl compounds containing hydroxyl groups, vinyl compounds containing nitrile groups, vinyl acid organic compounds, and olefins. Examples thereof include compounds, diene compounds, vinyl halide compounds, vinylidene halide compounds, maleimide compounds and the like.
Examples of the acrylate ester include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate.
Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate.
Examples of the vinyl compound containing a hydroxyl group include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.
Examples of the vinyl compound containing a nitrile group include acrylonitrile and methacrylonitrile.
Examples of the organic acid vinyl compound include vinyl acetate and vinyl propionate.
Examples of the olefin compound include ethylene, propylene, 1-butene, and 2-butene.
Examples of the diene compound include butadiene, isoprene, chloroprene and the like.
Examples of the vinyl halide compound include vinyl chloride and vinyl bromide.
Examples of the vinylidene halide compound include vinylidene chloride.
Examples of maleimide compounds include N-phenylmaleimide and N-methylmaleimide.
These vinyl monomers may be used alone or in combination of two or more.

  The foam molded body has continuous voids communicating with the outside between the foamed particles constituting the foam molded body. The shape of the voids in the foamed molded product is, for example, a three-dimensional network structure.

  The porosity of the foamed molded product is 5 to 65% by volume. Therefore, the foamed molded article is excellent in air permeability, liquid permeability / impregnation, and sound absorption. As for the porosity of a foaming molding, it is more preferable that it is 10-50 volume%, and it is further more preferable that it is 15-45 volume%.

The porosity of the foamed molded product can be measured, for example, as follows.
That is, first, the foamed molded product is allowed to stand for 24 hours or more in an environment of a temperature of 23 ° C. and a relative humidity of 50%. A rectangular parallelepiped sample having a specific size is cut out from the foamed molded product. The bulk volume is determined from the external dimensions of the sample. Next, the sample is submerged in a graduated cylinder containing ethanol at a temperature of 23 ° C. using a tool such as a wire mesh. Next, air existing between the expanded particles in the sample is degassed by applying a light vibration or the like to the sample. Then, taking into account the volume of a tool such as a wire mesh, the true volume (cm ³ ) of the sample read from the rise in the water level is measured. Since the bulk volume of the resulting sample and (cm ³⁾ and a true volume (cm ^3), porosity (%) is calculated by the following equation.
Porosity (%) = (bulk volume of sample (cm ³ ) −true volume of sample (cm ³ )) / bulk volume of sample (cm ³ ) × 100

  The expanded particles constituting the expanded molded body have a surface molten layer formed on the surface thereof. The surface molten layer is a layer formed by once melting a surface layer containing bubbles of expanded particles and then curing. Therefore, it can be said that the surface melt layer is a layer having almost no bubbles. The surface melt layer is a layer different from a so-called skin layer formed at the time of producing the foamed particles. For example, the thickness of the surface melt layer is larger than that of the skin layer.

The surface melt layer may contain a softening melt. As the softening melt, for example, one or more selected from liquid paraffin, castor oil, beef tallow, coconut oil, peanut oil, rapeseed oil, dioctyl phthalate, dioctyl adipate, glycerin higher fatty acid ester, acetylated glyceride, butyl stearate and the like are used. .
The surface molten layer preferably contains liquid paraffin. In this case, the surface molten layer can be easily formed. Therefore, it becomes possible to make the porosity of a foaming molding higher.

  A foaming molding has a connection part which connects expanded particles mutually. The connecting portion is formed by extending the surface molten layer after the surfaces of the adjacent expanded particles are fused to each other. Therefore, it can be said that the connection part is formed from the surface molten layer, and is comprised from the resin reservoir part which has few bubbles. Moreover, when a surface melt | fusion layer contains a liquid paraffin, a connection part can also contain a surface paraffin.

The surface melt layer and the connecting portion can be formed, for example, as follows in the manufacturing process of the foam molded article.
That is, first, foamed particles are filled into the mold. Next, steam or the like is supplied into the mold and the mold is heated. Thereby, part of the surface of the expanded particles is fused to each other. Next, a time for allowing the foamed molded body formed by fusing the foamed particles to remain in the mold without actively cooling by water cooling or the like is provided. This standing time can be referred to as a high temperature aging time, for example. By providing this high temperature aging time, the above-mentioned surface melt layer and connecting portion can be formed. The connecting portion is presumed to be formed by reducing the volume of the foamed particles by forming the surface melted portion during the high temperature aging time after a part of the surface of the foamed particles is fused to each other. The Therefore, a foam having a conventional void produced by fusing part of the surface of the foam particles in the mold and then compressing the foam particles entirely by applying pressure in the mold with compressed air or the like. The structure is different from the molded body. Since the foamed molded article of the present invention has a connecting part formed by extending the surface melting part as described above, it can have both a high porosity and an excellent bending property.
The temperature during aging is, for example, 85 to 105 ° C. The high temperature aging time can be appropriately adjusted. The high temperature aging time until the connection portion is generated is considered to be about 2 to 60 seconds, for example.

  The surface of the expanded particles filled in the mold is preferably covered with a softening melt. In this case, the connecting portion is easily formed. The amount of the softening melt added is, for example, preferably 0.1 to 25 parts by mass, more preferably 3 to 10 parts by mass with respect to 100 parts by mass of the expanded particles. In this case, the porosity of the foamed molded product can be further increased. As the softening and melting agent, liquid paraffin is preferable. Covering the foamed particles with the softening melt can be performed by, for example, a ribbon blender, a tumbler, a screw mixer, or the like. Further, by supplying the softening melt agent together with the foamable resin particles into the prefoaming machine and prefoaming the foamable resin particles while mixing both, it is possible to obtain foamed particles whose surfaces are coated with the softening melt agent. .

  In the bending test of the foamed molded product, it is preferable that material breakage occurs at the connecting portion. In this case, the above-mentioned bending characteristics of the foamed molded product can be further improved. The bending test of the foamed molded product can be performed based on, for example, JIS K7221-2 (2006).

Apparent density of the expanded molded article, is not particularly limited, generally is preferably 9~50kg / m ^3, more preferably 9~30kg / m ^3. As apparent density of the expanded molded article is in the range of 9~30kg / m ^3, when the bulk density to obtain a foamed molded using foamed particles 9~30kg / m ³ is especially porosity high expansion It becomes easy to obtain a molded body. The apparent density is measured as follows.
Specifically, first, the volume is determined from the outer dimensions of the foam molded article, and then the mass of the foam molded article is measured. Then, the apparent density (kg / m ³ ) of the foamed molded product is calculated by dividing the mass by the volume. In addition, when the external dimensions of the foamed molded product cannot be measured, a plurality of rectangular parallelepiped or cubic test pieces are cut out from the foamed molded product, the mass of the test pieces is measured, and the sum of the masses is calculated from the external dimensions of the test pieces. You may obtain | require the apparent density (kg / m < ³ >) of a foaming molding by dividing | segmenting by the sum of the calculated | required volume.
The bulk density (kg / m ³ ) of the expanded particles is prepared by preparing a 1 L graduated cylinder, filling the empty graduated cylinder with the expanded particles up to the 1 L mark, and the weight (g) of the expanded particles per liter. It is calculated | required by measuring.

The foam molded body is used as, for example, a sound absorbing material. Moreover, the composite of a foaming molding and an inorganic material can be obtained by filling the space | gap of a foaming molding with flame-retardant inorganic materials, such as gypsum and cement, and making it solidify. This composite is used as an incombustible heat insulating material.
In addition, the foam molded body is also used as a mold for producing a metal porous body. Specifically, by heating the foamed molded product in which the metal powder slurry is poured into the voids, the metal powder is sintered and the foamed molded product disappears. As a result, a metal porous body is obtained as described above.

(Example)
Next, a foamed molded product according to the example is produced.
As shown in FIG. 1, the foamed molded body 1 of this example is composed of a large number of foamed particles 2 fused to each other. The foam molded body 1 has continuous voids 3 communicating with the outside between the foamed particles 2, and the voids 3 are formed in a three-dimensional network shape (see FIGS. 2 and 4). The expanded particles 2 constituting the expanded molded body 1 have a surface molten layer 21 formed on the surface thereof (see FIGS. 3 and 5). The foam molded body 1 has a connecting portion 22 in which the surface melt layers 21a and 21b are stretched after the adjacent foam particles 2a and 2b are fused to each other. The connecting portion 22 connects the adjacent expanded particles 2a and 2b to each other.

The manufacturing method of the foaming molding of this example is demonstrated.
First, “Styrodia PA200” manufactured by JSP Co., Ltd. was prepared as expandable particles (expandable polystyrene resin particles). Next, the expanded particles were produced by expanding the expandable particles to a predetermined expansion ratio. Next, a predetermined amount of liquid paraffin was added using a screw mixer to coat the surface of the foamed particles with liquid paraffin.

Next, the foamed particles were filled into a mold of a German Mordex molding machine. This mold has a rectangular parallelepiped cavity of 700 mm × 500 mm × 50 mm. Next, the inside of the mold was heated for 7 seconds by supplying water vapor with a gauge pressure of 0.06 MPa into the mold. Next, after the supply of water vapor was stopped, the inside of the mold was left for 60 seconds. Thereafter, the foamed molded product was taken out from the mold. In this way, a foamed molded product was obtained. In this example, the expansion ratio is 30 times (bulk density 35 kg / m ³ ), 50 times (bulk density 21 kg / m ³ ), 70 times (bulk density 15 kg / m ³ ), or 90 times (bulk density 12 kg / m). ^{In 3} ), 12 types of foamed molded articles (Examples 1 to 12) were prepared using foamed particles having an addition amount of liquid paraffin of 3 parts by mass, 6 parts by mass, or 9 parts by mass.

(Comparative example)
Next, a foamed molded article of a comparative example was produced as follows.
Specifically, first, the same operation as in the above-described example was performed until water vapor was supplied. Next, after the supply of water vapor was stopped, the mold was cooled by pouring cold water into the mold for 5 seconds and then leaving it for 60 seconds. Thereafter, the foamed molded product was taken out from the mold. In this way, a foamed molded product was obtained. In this example, as in the example, expanded particles having an expansion ratio of 30 times, 50 times, 70 times, or 90 times and an addition amount of liquid paraffin of 3 parts by weight, 6 parts by weight, or 9 parts by weight Using, 12 types of foam-molded articles (Comparative Examples 1 to 12) were produced.

(Experimental example)
Next, an Example and a comparative example are compared.
About the foaming molding of an Example, an enlarged photograph is shown in FIG.2 and FIG.3, and a scanning electron microscope (SEM) photograph is shown in FIG.4 and FIG.5. Moreover, the enlarged photograph regarding the foaming molding of a comparative example is shown in FIG.6 and FIG.7, and a SEM photograph is shown in FIG.8 and FIG.9. 2, 4, 6, and 8 are photographs showing the surface of the foam molded article, and FIGS. 3, 5, 7, and 9 are photographs showing cross sections of the foam molded article.

  As can be seen from FIGS. 3 and 5, it can be seen that the foamed molded body of the example has a surface molten layer 21 on the surface of the foamed particles 2. On the other hand, as is known from FIGS. 7 and 9, the foamed molded product 9 of the comparative example does not have a surface melt layer as in the example. On the surface of the foamed particles 91 constituting the foamed molded product 9 according to the comparative example, only the skin layer 92 that was also present in the foamed particles 91 before molding is present.

  Moreover, as known from FIGS. 2 to 5, the foamed molded body 1 of the example has a connecting portion 22 that connects the foamed particles 2 to each other, and most of the adjacent foamed particles 2 ( 90% or more) are connected by the connecting portion 22. As is known from FIG. 4, after the adjacent foam particles 2a and 2b are fused to each other, the connecting portion 22 is pulled in the connecting direction of the foam particles 2a and 2b. It will be extended. On the other hand, as is known from FIGS. 6 to 9, the foamed molded body 9 of the comparative example does not have a connecting portion as in the example. In the foamed molded article 9 of the comparative example, the adjacent foamed particles 91 are only partially fused in the skin layer 92.

In this example, a plurality of foamed molded products having different porosity and apparent density were produced using the above-mentioned foamed particles having different foaming ratios and addition amounts of liquid paraffin. These specific values are shown in Tables 1 and 2.
Next, the bending strength, bending elastic modulus, and bending deflection of these foamed molded products were measured as follows. The results are shown in Tables 1 and 2.

"Bending strength, flexural modulus, bending deflection"
Based on JIS K7221-2, the bending strength, bending elastic modulus, and bending deflection of the foamed molded product were obtained using a test specimen cut from the vicinity of the center of the foamed molded product. The bending deflection is the amount of deflection when the test piece is broken, and the bending strength is the stress when the test piece is broken. The measurement was performed using a measuring apparatus A having a fulcrum distance of 300 mm under the conditions of a temperature of 23 ° C., a relative humidity of 50%, and a test speed of 20 mm / min.

  When the foamed molded products of Examples 1 to 12 and the foamed molded products of Comparative Examples 1 to 12 were compared with each other having a close porosity, the foamed molded products of the Examples had bending strengths compared to the foamed molded products of the Comparative Examples, Bending elastic modulus and bending deflection were improved (see Tables 1 and 2). Moreover, in the foaming molding of the Example, the connection part had destroyed material in the cross section destroyed by the bending test. That is, it can be seen that the foamed molded article having the above-described characteristic configuration in which the surface of the foamed particles has a surface melt layer and the above-mentioned connecting portion is provided between the foamed particles has excellent bending characteristics. In addition, when the porosity is increased, the bending characteristics of the foamed molded product tend to be deteriorated. As is known from Tables 1 and 2, the foamed molded product of the example has a higher porosity and superior to the comparative example. Combines bending properties.

  Moreover, in the foaming molding which has a connection part between foaming particles, it turns out that a foaming molding with a very high porosity exceeding 40 volume% is realizable (refer Table 1 and Table 2). Although not shown in the table, for example, by setting the addition amount of liquid paraffin to 25 parts by mass, it is 47% by volume, which greatly exceeds the theoretical porosity when the expanded particles are close-packed assuming that they are spheres. It has been confirmed that a foamed molded article having a high porosity can be realized.

DESCRIPTION OF SYMBOLS 1 Foam molding 2 Foamed particle 21 Surface molten layer 22 Connection part 3 Space | gap

Claims (3)

A foamed molded article comprising a large number of polystyrene resin foam particles fused to each other, and having continuous voids connecting the polystyrene resin foam particles,
The polystyrene resin foam particles constituting the foamed molded article have a surface melt layer formed on the surface by melting the surface layer of the polystyrene resin foam particles,
The foamed molded article has a connecting portion that connects the polystyrene resin foam particles to each other, wherein the surface melt layer is stretched after adjacent polystyrene resin foam particles are fused to each other. ,
The apparent density of the foamed molded product is 9-30 kg / m ³ ,
A foamed molded product having a porosity of 5 to 65% by volume.   In the bending test of the said foaming molding, the said connection part destroys material, The foaming molding of Claim 1 characterized by the above-mentioned.   The foam molding according to claim 1 or 2, wherein the surface melt layer contains liquid paraffin.