JP2012081765A - Thermoplastic resin foamed molding, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin foamed molding having a high porosity, and excelling in shape retaining properties, and a mechanical strength using thermoplastic resin preliminarily foamed particles capable of manufacturing conveniently and economically.SOLUTION: A thermoplastic resin in-mold foamed molding in which a part where the porosity in the molding is not greater than 10%, and a part where the porosity is not less than 10% and not greater than 60% are found so as to be approximately comparted, and the porosity in the molding is uneven is obtained by in-mold foam molding using thermoplastic resin preliminarily foamed particles in which the part where the porosity in the molding is not greater than 10% has a L/D of not less than 0.8 and not greater than 1.2, and using thermoplastic resin preliminarily foamed particles in which the part where the porosity is not less than 10% and not greater than 60% has a L/D of not less than 2 and not greater than 10, wherein, in L/D, L is a length of the longest part of a formed particle, and D is an average value of the longest diameter Dand the shortest diameter Din a sectional face perpendicular to the L direction, and L/D is calculated by the following formula: D=(D+D)/2.

Description

  The present invention relates to a thermoplastic resin in-mold foam molded product having a non-uniform porosity in a molded product and a method for producing the same.

  As a method for producing a foamed molded article having continuous voids formed by molding thermoplastic resin pre-foamed particles, a molded product having a structure in which spherical polystyrene foam particles are solidified with an adhesive and provided with continuous voids is known. (Patent Document 1). However, this molded article has a problem that the adhesion of the expanded particles depends only on the adhesiveness of the adhesive, and sufficient adhesiveness cannot be obtained and is easily broken.

  Also for the polyolefin resin, columnar polyolefin resin foamed particles having an L / D of 2 to 10 were filled in the mold so that the filling rate was 40 to 55% and the particles faced in irregular directions. Thereafter, a molded body to be heated with steam (Patent Document 2), a method of thermoforming polypropylene resin expanded particles having irregularities such as a hollow cylinder or hollow irregular shape or a cross-shaped cross section (Patent Document 3, Patent Document) 4) is disclosed. Furthermore, there is a foamed molded article having a porosity of 10 to 60% using drum-shaped pre-expanded particles (Patent Document 5). In any of these methods, in order to obtain water permeability, air permeability, and sound absorption, a pre-expanded particle having an irregular shape or a pre-expanded particle having a large L / D is used to form voids in the foam molded body. It is to be provided. However, since the foamed molded article having such a structure contains many voids, mechanical properties such as compressive strength are reduced or the fusion strength between the pre-expanded particles is reduced as compared with a molded article having no voids. The pre-expanded particles are easy to peel off at the end surface portion of the foam molded product, that is, the shape retainability is poor. The fusing strength is improved by increasing the molding heating temperature, but on the other hand, the porosity is lowered and water permeability, sound absorption, etc. are lowered. That is, it is desired to prevent end face peeling and improve the strength of the molded product while maintaining air permeability, water permeability, and sound absorption performance.

JP-A-4-153026 JP-A-3-224724 JP 7-138399 A JP 7-138400 A JP 2000-302909 A

  An object of the present invention is to use thermoplastic resin pre-expanded particles that can be easily and economically produced, and has a high porosity and has a shape retention property or excellent mechanical strength. It is in providing a body and its manufacturing method.

  The inventors of the present invention have made extensive studies to solve the above-mentioned problems, and when looking at the entire molded body, the molded body parts required for properties such as mechanical strength such as compressive strength and peeling / cracking are limited. Even if the properties of the molded body, such as water permeability, air permeability, and sound absorption, are reduced, the overall properties of the molded body, such as sound absorption, are only slightly reduced. I found out that I could make it. In other words, by performing in-mold foam molding so that different void ratios in the molded body become non-uniform, a molded body having shape retention can be obtained while maintaining an appropriate void ratio, and sound absorption is achieved in a wide sound absorption range. As a result, the present invention was completed.

That is, according to the first aspect of the present invention, a portion having a porosity of less than 10% and a portion having a porosity of 10% or more and 60% or less exist in a substantially partitioned shape, and the porosity in the molded body is not uniform. A thermoplastic resin-in-mold foam-molded article, wherein the part having a porosity of less than 10% uses thermoplastic pre-expanded particles having an L / D of 0.8 or more and 1.2 or less, and the porosity is 10%. The thermoplastic resin foam-molded article is characterized in that the portion of 60% or less is formed by in-mold foam molding using thermoplastic pre-expanded particles having an L / D of 2 or more and 10 or less.
Here, L / D is L is the length of the longest part of the expanded particles, D is an average value of the maximum diameter Dmax and the minimum diameter Dmin in a cross section perpendicular to the L direction, and is calculated by the following equation.
D = (D _max + D _min ) / 2

In the second aspect of the present invention, a portion having a porosity of less than 10% and a portion having a porosity of 10% or more and 60% or less exist in a substantially partitioned shape, and the porosity in the molded body is not uniform. A method for producing a foamed molded article in a thermoplastic resin mold, wherein a sectioned mold is used, and a L / D is 0 in a mold section corresponding to a portion having a porosity of less than 10% in the molded body. .8 or more and 1.2 or less thermoplastic pre-expanded particles, and L / D is 2 or more and 10 or less thermoplastic pre-expanded particles in the mold section corresponding to the portion having the porosity of 10% or more and 60% or less It is related with the manufacturing method of the thermoplastic resin foaming molding characterized by filling and heat-molding.
Here, L / D is L is the length of the longest part of the expanded particles, D is an average value of the maximum diameter Dmax and the minimum diameter Dmin in a cross section perpendicular to the L direction, and is calculated by the following equation.
D = (D _max + D _min ) / 2

  In a preferred embodiment, the thermoplastic pre-expanded particles having an L / D of 0.8 or more and 1.2 or less have a cell diameter of 200 μm or more and 400 μm or less, and the L / D is 2 or more and 10 or less. The cell diameter is 30 μm or more and 150 μm or less.

  In another preferred embodiment, the thermoplastic pre-expanded particles have two melting peaks in a DSC curve obtained by differential scanning calorimetry, and the low-temperature peak melting heat α (J / g), The β / (α + β) value of the thermoplastic pre-expanded particles having the L / D of 0.8 or more and 1.2 or less is 0.15 or more and 0.35, when the heat of fusion β (J / g) of the high temperature side peak is used. The β / (α + β) value of the thermoplastic pre-expanded particles having L / D of 2 or more and 10 or less is 0.35 or more and 0.75 or less.

  In a preferred embodiment, the thermoplastic pre-expanded particles having an L / D of 0.8 to 1.2 are spherical pre-expanded particles, and the thermoplastic pre-expanded particles having an L / D of 2 to 10 are It is a rod-shaped pre-expanded particle.

  In a preferred embodiment, the outer peripheral portion of the molded body has a porosity of less than 10%, and the other is constituted by a porosity of 10% or more and 60% or less.

  Moreover, in a preferred embodiment, the foamed molded product is any one of an automotive raising material, a tibia pad, a luggage box, and a side projection material.

  In the present invention, by making the porosity in one molded body non-uniform, it has properties depending on the porosity such as water permeability, air permeability, sound absorption, etc., and peeling and cracking hardly occur. It becomes possible to stably and economically obtain a molded product that maintains the desired strength. Further, since the porosity is not uniform, sound absorption characteristics can be expressed in a wide sound absorption range.

  This foamed molded article can be suitably used as a sound-absorbing material, a water-permeable material, etc. in automobile members, civil engineering / building materials, industrial materials and the like. In particular, it can be suitably used when sound absorbing performance is imparted to automobile members such as a raising material, a tibia pad, a luggage box, and a side projection material.

It is the figure shown about L / D of the thermoplastic resin pre-expanded particle used for this invention. It is an example of the DSC curve obtained when measuring the thermoplastic resin pre-expanded particle of this invention using a differential scanning calorimeter. The horizontal axis is the temperature, and the vertical axis is the endothermic amount. The low temperature side is α and the high temperature side is β.

  Hereinafter, the present invention will be described in detail.

  The thermoplastic resin used in the present invention can be used as long as it is a thermoplastic resin used for in-mold foam molding, and examples thereof include polystyrene resins, polyolefin resins, and polymethyl methacrylate resins.

  Examples of polystyrene resins that can be used in the present invention include not only general foamable polystyrene resins, but also, for example, polystyrene resins containing 50% or more of styrene or methylstyrene, high impact polystyrene resins, styrene, Examples thereof include copolymer resins such as butadiene, styrene-ethylene copolymer, methyl methacrylate, and maleic anhydride, and these are used alone or in combination of two or more.

  Examples of polyolefin resins that can be used in the present invention include low / medium / high density polyethylene, linear low / ultra low density polyethylene, polyethylene resins represented by ethylene-vinyl acetate copolymer, polypropylene, and ethylene-propylene. Examples thereof include a polypropylene resin represented by a random copolymer and an ethylene-propylene block copolymer.

  Among these, polyolefin resin is preferably used, and polypropylene resin is more preferably used.

  The polypropylene resin that can be used in the present invention is a polymer comprising propylene monomer units of 50% by weight or more, preferably 80% by weight or more, and more preferably 90% by weight or more, and among them, a Ziegler type titanium chloride catalyst or Those having high stereoregularity polymerized with a metallocene catalyst are preferred. Specific examples include, for example, propylene homopolymer, ethylene-propylene random copolymer, propylene-butene random copolymer, ethylene-propylene-butene random copolymer, ethylene-propylene block copolymer, maleic anhydride -A propylene random copolymer, a maleic anhydride-propylene block copolymer, a propylene-maleic anhydride graft copolymer, etc. are mentioned, These are used individually or in mixture. In particular, an ethylene-propylene random copolymer, a propylene-butene random copolymer, and an ethylene-propylene-butene random copolymer can be suitably used. Further, these polypropylene resins are preferably non-crosslinked, but crosslinked resins can also be used.

  When a polypropylene resin is used as the thermoplastic resin in the present invention, the melt index (hereinafter referred to as MI) measured at a temperature of 230 ° C. and a load of 2.16 kg in accordance with JIS K7210 is 0.1 g / 10 min or more and 7 g / min. It is preferably 10 minutes or less, more preferably 2 g / 10 minutes or more and 6 g / 10 minutes or less. When MI is less than 0.1 g / 10 min, the foaming force when producing pre-expanded particles is low, and it tends to be difficult to obtain pre-expanded particles with a high expansion ratio. Moreover, it tends to be difficult to ensure the fusion strength between the pre-expanded particles when a foamed molded body is obtained. When MI exceeds 7 g / 10 minutes, it tends to be difficult to control the porosity of the foamed molded product with a stable value.

  The polypropylene resin preferably has a melting point of 130 ° C. or higher and 168 ° C. or lower, more preferably 135 ° C. or higher and 160 ° C. or lower, particularly preferably, in order to obtain a foamed molded article having excellent mechanical strength and heat resistance. 140 ° C. or higher and 155 ° C. or lower. When the melting point is within this range, there is a strong tendency to easily balance moldability, mechanical strength, and heat resistance. Here, the melting point means that 1 to 10 mg of resin is heated from 40 ° C. to 220 ° C. at a rate of 10 ° C./min by a differential scanning calorimeter, then cooled to 40 ° C. at a rate of 10 ° C./min, and again The peak temperature of the endothermic peak in the DSC curve obtained when the temperature is increased to 220 ° C. at a rate of 10 ° C./min.

  The pre-expanded particles used in the present invention have the above thermoplastic resin as a base resin, and the shape thereof is not particularly limited, and pre-expanded particles having any shape can be employed. For example, so-called deformed pre-expanded particles such as substantially spherical shapes, rod-shaped particles having an L / D of 2 or more and 10 or less, and cylindrical particles can be used.

Here, L / D referred to in the present invention is, as shown in FIG. 1, L is the length of the longest part of the expanded particles, D is an average value of the maximum diameter Dmax and the minimum diameter Dmin in a cross section perpendicular to the L direction. And is calculated by the following formula.
D = (D _max + D _min ) / 2

  The cross-sectional shape perpendicular to the L direction of the thermoplastic pre-expanded particles is a closed curve without a concave portion such as a circle or an ellipse, and Dmax and Dmin take substantially constant values along the L direction. Specific examples of the pre-expanded particles include a cylindrical shape and an elliptical column shape. L / D can be adjusted easily by melting the raw material resin with an extruder, extruding it from a die with many pores, drawing and cooling it into a strand, cutting it into pellets, and cutting length. Can be adjusted. However, when preparing the pre-expanded particles from these pellets, it is preferable that the pre-expanded particles are prepared to be about 2 to 3 times longer than the required length because the stretching strain tends to be relaxed by heating and the length direction shrinks. .

  The thermoplastic resin in-mold foam molded product of the present invention is characterized in that the porosity in the molded product is not uniform. In the present invention, the porosity is non-uniform, when a plurality of cubes of 30 mm × 30 mm × 30 mm are cut out from the molded body so as not to include the surface skin layer, and the porosity is measured for each, a difference of 5% or more Says having a part. Here, the porosity means that a rectangular solid sample having a predetermined size (for example, 30 × 30 × 30 mm) is cut out from the foam so as not to include the surface skin layer, the apparent volume is obtained from the outer dimensions, and further the rectangular parallelepiped sample. Is immersed in a graduated cylinder containing a certain amount of ethanol, the increased volume (true volume) at that time is measured, and the difference between the apparent volume and the true volume is divided by the apparent volume.

  The non-uniform portions may be arranged in any manner, but preferably, the portions having different void ratios are present in a substantially partitioned shape, and the void ratio in the molded body is less than 10%. In addition, it is preferable that a site of less than 7% and a site of porosity of 10% to 60%, preferably 15% to 55% are present in a substantially partitioned shape. Most preferably, the outer peripheral portion of the molded body is made with a porosity of less than 10%, and the other is constituted with a porosity of 10% or more and 60% or less. As described above, the non-uniform porosity in the molded body provides a sound absorption effect in a wide sound absorption range in the case of sound absorption performance. In addition, because there are parts having different porosity in a substantially partitioned shape, the part that wants to give strength and shape retention is set to a low porosity, and the part that wants to give water permeability and sound absorption is set to a high porosity. It becomes easy. Furthermore, by forming the outer periphery of the molded body with a porosity of less than 10% and configuring the other with a porosity of 10% or more and 60% or less, the strength or shape can be maintained while having more voids for water permeability and sound absorption. Is possible.

  In the present invention, in order to make the porosity non-uniform, in the thermoplastic resin pre-expanded particles to be used, use different resin types, use resins having different melting points, and pre-expanded particles having different β / (α + β) values. Or a method of using pre-expanded particles having different shapes, and two or more of these methods may be used in combination.

  Here, the β / (α + β) value means that 1 to 10 mg of foamed particles are heated from 40 ° C. to 220 ° C. at a heating rate of 10 ° C./min with a differential scanning calorimeter in differential scanning calorimetry of the foamed particles. In the DSC curve obtained in Fig. 2 (B), when the low temperature side contact between the straight line passing through the maximum point A and the DSC curve is B and the high temperature side contact is C, the area surrounded by the line segment AB and the DSC curve To the low-temperature side peak heat of fusion α (J / g), and from the area surrounded by the line segment AC and DSC curve, the high-temperature side peak heat of fusion β (J / g).

  In the present invention, pre-expanded thermoplastic resin particles having an L / D of 2 or more and 10 or less (hereinafter sometimes referred to as rod-shaped pre-expanded particles) and pre-cured thermoplastic resins having an L / D of 0.8 or more and 1.2. It is preferable to use expanded particles (hereinafter sometimes referred to as spherical pre-expanded particles).

  An embodiment in which these pre-expanded particles are used will be described in detail below.

  By employing rod-shaped pre-expanded particles having an L / D of 2 or more and 10 or less, it is easy to form a high void while maintaining an appropriate contact area between the expanded particles.

  The rod-shaped pre-expanded particles preferably have a cell diameter of 30 μm to 150 μm, and more preferably 50 μm to 100 μm. When the cell diameter is within this range, it is easy to firmly fuse the foamed particles while maintaining the voids generated when filling the mold. When the cell diameter is less than 30 μm, sinking and shrinkage are likely to occur when the foamed molded article is formed, and the shape retainability may deteriorate. When the cell diameter exceeds 150 μm, the porosity of the foamed molded product tends to be low. In particular, the porosity tends to decrease in the surface layer in contact with the mold surface.

  Further, the rod-shaped pre-expanded particles have two melting peaks in the DSC curve obtained by differential scanning calorimetry, the heat of fusion α (J / g) of the low temperature side peak, and the heat of fusion β (J of the high temperature side peak) / G), the β / (α + β) value is preferably 0.35 or more and 0.75 or less, and more preferably 0.40 or more and 0.70 or less. When the β / (α + β) value is less than 0.35, it may be difficult to increase the porosity of the foam molded article. This is presumably because the secondary foaming power of the foamed particles is increased and the porosity is reduced during molding. If β / (α + β) exceeds 0.75, fusion between the expanded particles may be difficult. When the temperature of the steam used for molding is increased in order to promote fusion, the porosity of the foamed molded product is lowered, and there is a risk that it is difficult to ensure both porosity and fusion.

  By using rod-shaped pre-expanded particles satisfying the above requirements, it becomes easy to produce a thermoplastic resin foam-molded part having a porosity of preferably 25% or more and 50% or less. The porosity of the foamed molded product is strongly related to the sound absorption characteristics, and the porosity is more preferably 30% or more and 45% or less. When the porosity is less than 25%, the sound absorption rate at the peak frequency is lowered, and sufficient sound absorption characteristics may not be obtained. If the porosity exceeds 50%, the contact area between the foamed particles is reduced, the foamed molded product is likely to be cracked, and the mechanical strength may be reduced.

  A substantially spherical pre-expanded particle having an L / D of 0.8 or more and 1.2 or less has a cell diameter of 200 μm or more and 400 μm or less, and has two melting peaks in a DSC curve obtained by differential scanning calorimetry. It is preferable that β / (α + β) value is 0.15 or more and 0.35 or less when the heat of fusion α (J / g) of the side peak and the heat of fusion β (J / g) of the high temperature side peak are used. By satisfying these requirements, there is a tendency that a thermoplastic resin foam-molded portion having a small magnification variation, high strength, and low porosity can be stably produced. Here, the L / D of the pre-expanded particles is as spherical as possible from the viewpoints of filling of the particles into the mold, fusion property after molding, and maintaining mechanical strength, and the L / D is preferably 0.00. It is preferably 9 or more and 1.1 or less, that is, L / D is close to 1.

  In the present invention, for example, by using such rod-shaped pre-expanded particles and spherical pre-expanded particles in combination, the porosity depending on water permeability, air permeability or sound absorption, shape maintenance of the molded product, or mechanical strength Holding can be possible. Since the sound absorption rate does not greatly depend on the expansion ratio of the rod-shaped pre-expanded particles, any expansion ratio can be selected. Moreover, although it changes with the applications to be applied, the expansion ratio of the pre-expanded particles is preferably 5 to 60 times. In particular, a bulking material for automobile use, a luggage box, a tibia pad, and the like are more preferably 15 times or more and 45 times or less.

  As a specific example of application, when the sound absorption performance is mainly required and it is desired to prevent the peeling of the raw material in the assembly line with the floor spacer, the spherical pre-foamed particles are used for the outer periphery, and the other parts are rod-shaped pre-foams having sound absorption performance. What is necessary is just to comprise with particle | grains. In addition, toolboxes that require sound absorption performance and bending rigidity are composed of rod-shaped pre-expanded particles that have sound absorption performance in parts that do not require bending rigidity, and spherical pre-expanded parts that require bending rigidity. It is possible to cope with the structure by using particles, or by mixing rod-shaped pre-expanded particles and spherical pre-expanded particles in a sea-island shape. Further, the present invention is also applied to a case where a fusion strength is partially required for assembling with a support part or other parts in a molded body mainly used for sound absorption or water permeation. As described above, it is possible to achieve both sound absorption, water permeability, air permeability and strength at the site where fusion strength is required in the product, and it can be applied to a wide range of applications.

  There is no particular limitation on the molding method that causes the portions having different porosity to be non-uniformly present, and a known method can be used. For example, the method of Unexamined-Japanese-Patent No. 2001-96559 is mentioned. Specifically, the pre-expanded particles do not pass through the mold, but the thermoplastic resin pre-expanded particles having different characteristics such as resin type, melting point, β / (α + β), shape and the like can contact each other. Comb-shaped rods are placed at appropriate intervals to partition the mold, and a mold with a pre-expanded particle filling feeder corresponding to the section is used to fill the necessary compartment with the pre-expanded particles. This is achieved by molding.

  When the parts having different porosity are arranged in a substantially partitioned shape, the setting of each section is not particularly limited, but the part that requires strength, peelability, fusibility, etc. is set so that the porosity is low, It is preferable to set other portions so as to increase the porosity. In filling the mold with pre-expanded particles, a method of filling the mold with known pre-expanded particles as they are and heat-molding with water vapor, and pressurizing inorganic gas to the pre-expanded particles A method in which the foamed particles are impregnated to give a predetermined foamed particle internal pressure and then filled into a mold and heat-molded with water vapor can be applied. It is preferable to heat mold by applying an internal pressure of 12 MPa or more and 0.27 MPa or less. In particular, it is preferable that the portion having a high porosity is set to 0.12 MPa or more and 0.19 MPa or less in absolute pressure, and the portion having a low porosity is set to 0.20 MPa or more and 0.27 MPa or less.

  The molded body obtained as described above has excellent sound absorption effect and water permeability effect, and can have the required mechanical strength and shape stability as a molded body, as a sound absorbing material, drain material, etc. For various purposes, for example, floor spacers, tibia pads, shock absorbers inside pillars, shock absorbers inside door rims, etc. It can be suitably used for wall materials (including core materials constituting wall materials) and wall materials (including core materials constituting the wall materials).

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example.

(Production of pre-expanded particles A)
Using MI: 4.5 g / 10 min, melting point: 144 ° C., ethylene content: 2.8%, butene content: 1.3% as the base resin, adding 300 ppm of talc as the cell nucleating agent, and in the extruder After being melt-kneaded in, extruded into a strand from a circular die, cooled with water, cut with a cutter, and a resin particle having a weight of 1.8 mg / grain, a cylindrical shape, and L / D of 6.3 is obtained. Obtained.

100 parts by weight (65 kg) of the obtained resin particles, 200 parts by weight of water, 0.5 parts by weight of basic tricalcium phosphate and 0.01 parts by weight of sodium alkyl sulfonate are charged into a pressure-resistant autoclave having a capacity of 0.35 m ³ . Under stirring, 16 parts of isobutane was added as a blowing agent, and then the autoclave contents were heated to a foaming temperature of 135 ° C. Thereafter, isobutane was additionally injected and the pressure was increased to a foaming pressure of 2.2 MPa. After maintaining the foaming temperature and the foaming pressure for 30 minutes, the valve at the bottom of the autoclave was opened and the autoclave contents were passed through a 4.4 mmφ orifice. Release under atmospheric pressure to obtain pre-expanded particles A. The obtained pre-expanded particles had L / D: 2.2, cell diameter: 103 μm, β / (α + β): 0.60, and bulk density: 0.019 g / cm ³ .

(Production of pre-expanded particles B)
Pre-expanded particles, except that the same resin particles as used to produce pre-expanded particles A were used, except that the autoclave contents were heated to a foaming temperature of 130 ° C. and isobutane was additionally injected to increase the foaming pressure to 2.4 MPa. In the same manner as A, expanded particles B having L / D: 2.2, β / (α + β): 0.70, and bulk density: 0.019 g / cm ³ were obtained.

(Pre-expanded particles C)
DBS45 (45 times product) manufactured by Kaneka Co., Ltd. (hereinafter, expanded particles C (L / D: 1.05, β / (α + β): 0.25)) was used.

Example 1
Pre-expanded particles A and pre-expanded particles C were used. Using a block-shaped mold of 300 × 400 × 50 mm, the pre-expanded particles were impregnated with air by air pressure treatment, the pre-expanded particles A were 0.13 MPa in absolute pressure, and the pre-expanded particles C were 0.21 MPa. Internal pressure was applied.

  In the filling process, the foamed particles C and foamed particles A are filled in this order with the mold opened 2 mm, and then the mold is completely closed, and the pre-foamed particles are heated and fused with steam at a gauge pressure of 0.22 MPa. Do. Thereafter, water cooling was performed for 60 seconds to release the foam. The foamed molding obtained here has many voids and contains a large amount of water content by steam / cooling water, so it is left at room temperature for 1 hour, then dried at 75 ° C. for 24 hours and then cured at room temperature for 24 hours. As a result, a foamed molded article having non-uniform porosity was obtained.

(Example 2)
The mold used in Example 1 has a block shape of 300 × 400 × 50 mm, and is partitioned with a substantially outer peripheral end portion 50 mm and the inside by a comb member. The comb portion is made of stainless spring steel, and the comb length is 49 mm. A foamed molded article having both a sufficient porosity and a shape retaining property was obtained in the same manner as in Example 1 except that one having a diameter of 2.5 mm and a comb spacing of 2.5 mm was used.

(Example 3)
In Example 2, except that the pre-expanded particles C were replaced with the pre-expanded particles B, a foam-molded product having both the ensured porosity and shape retention was obtained in the same manner as Example 2.

(Comparative Example 1)
The foamed particles A used in Example 1 were impregnated with air by air pressure treatment to obtain pre-foamed particles having an internal pressure of 0.13 MPa as an absolute pressure. This was filled in a 300 × 400 × 50 mm block-shaped mold, heated with steam having a gauge pressure of 0.22 MPa, and water-cooled for 60 seconds to obtain a foam formed only with expanded particles A. This was left to stand at room temperature for 1 hour, and then subjected to drying at 75 ° C. for 24 hours and curing at room temperature for 24 hours.

  Table 1 shows the results of evaluation of the obtained molded body.

  As described above, as for the porosity, a cubic sample of 30 × 30 × 30 mm was cut out from the foam so as not to include the surface skin layer, and the apparent volume was determined from the external dimensions. Furthermore, a rectangular parallelepiped sample is immersed in a graduated cylinder containing a certain amount of ethanol, the volume increased (true volume) at that time is measured, and the value obtained by dividing the difference between the apparent volume and the true volume by the apparent volume is a gap. Defined as rate.

The sound absorption coefficient was measured by two methods, ie, a normal incidence measurement and a measurement method using a reverberation chamber. The numbers in the table represent the highest values. The normal incidence type measurement was based on ASTME1050, and the normal incidence sound absorption coefficient at 500 to 6400 Hz was measured with a sample thickness of 40 mm. The sample was cut out from the obtained foamed molded article with a thickness of 40 mm so that the surface having the surface skin layer became the sound wave incident surface. The measurement was performed in a state where the sample was in close contact with the rigid wall that reflects sound waves, that is, in the absence of air behind. For the measurement, a normal incidence sound absorption measuring device SR-4100 manufactured by Ono Sokki Co., Ltd. was used. The reverberation chamber was measured according to JIS A1409 using a 9 m ³ reverberation chamber (manufactured by Nittobo Acoustic Engineering) and a sample size of 700 × 700 mm at 500 to 5000 Hz. Here, the sample used for the reverberation chamber measurement was a laminate of molded bodies molded with the molds shown in the examples or comparative examples.

  Peeling evaluation was performed by dropping the molded body 10 times from a position having a height of 1 m so that the corners hit the floor surface, and evaluating whether or not the pre-expanded particles were peeled from the molded body. Evaluation criteria were as follows: No peeling: ○, 2 times or less peeling: Δ, 3 times or more peeling: x.

Claims (12)

A thermoplastic resin-in-mold foam-molded article in which a portion having a porosity of less than 10% and a portion having a porosity of 10% or more and 60% or less exist in a substantially partitioned shape, and the porosity in the molded body is non-uniform. There,
The part where the porosity is less than 10% uses thermoplastic pre-expanded particles having an L / D of 0.8 or more and 1.2 or less, and the part where the porosity is 10% or more and 60% or less is L / D. A thermoplastic resin foam-molded article obtained by in-mold foam molding using 2 or more and 10 or less thermoplastic pre-foamed particles.
Here, L / D is L is the length of the longest part of the expanded particles, D is an average value of the maximum diameter Dmax and the minimum diameter Dmin in a cross section perpendicular to the L direction, and is calculated by the following equation.
D = (D _max + D _min ) / 2   The cell diameter of the thermoplastic pre-expanded particles having an L / D of 0.8 to 1.2 is 200 μm to 400 μm, and the cell diameter of the thermoplastic pre-expanded particles having an L / D of 2 to 10 is 30 μm. The thermoplastic resin foam molded article according to claim 1, wherein the thermoplastic resin foam molded article is 150 µm or less.   The thermoplastic pre-expanded particles have two melting peaks in the DSC curve obtained by differential scanning calorimetry, the heat of fusion α (J / g) of the low temperature side peak, and the heat of fusion β (J of the high temperature side peak) / G), the β / (α + β) value of the thermoplastic pre-expanded particles having an L / D of 0.8 or more and 1.2 or less is 0.15 or more and 0.35 or less, and the L / D is The thermoplastic resin foam molding according to claim 1 or 2, wherein the β / (α + β) value of the thermoplastic pre-expanded particles of 2 or more and 10 or less is 0.35 or more and 0.75 or less. body.   The thermoplastic pre-expanded particles having an L / D of 0.8 to 1.2 are spherical pre-expanded particles, and the thermoplastic pre-expanded particles having an L / D of 2 to 10 are rod-shaped pre-expanded particles. Item 4. The thermoplastic resin foam molded article according to any one of Items 1 to 3.   The thermoplastic resin foam molded article according to any one of claims 1 to 4, wherein the outer peripheral portion of the molded article has a porosity of less than 10%, and the other is constituted by a porosity of 10% or more and 60% or less. .   The thermoplastic foam-molded article according to any one of claims 1 to 5, wherein the foam-molded article is any one of an automotive raising material, a tibia pad, a luggage box, and a side projection material. A thermoplastic resin in-mold foam molded article in which a portion having a porosity of less than 10% and a portion having a porosity of 10% or more and 60% or less exist in a substantially partitioned shape, and the porosity in the molded body is not uniform. A manufacturing method comprising:
Using compartmentalized molds,
Filling a mold section corresponding to a portion having a porosity of less than 10% in the molded body with thermoplastic pre-expanded particles having an L / D of 0.8 or more and 1.2 or less,
Filling a mold section corresponding to the portion having a porosity of 10% or more and 60% or less with thermoplastic pre-expanded particles having an L / D of 2 or more and 10 or less,
A method for producing a thermoplastic resin foam-molded article, characterized by heat molding.
Here, L / D is L is the length of the longest part of the expanded particles, D is an average value of the maximum diameter Dmax and the minimum diameter Dmin in a cross section perpendicular to the L direction, and is calculated by the following equation.
D = (D _max + D _min ) / 2   The cell diameter of the thermoplastic pre-expanded particles having an L / D of 0.8 to 1.2 is 200 μm to 400 μm, and the cell diameter of the thermoplastic pre-expanded particles having an L / D of 2 to 10 is 30 μm. The method for producing a thermoplastic resin foam molded article according to claim 7, wherein the thermoplastic resin foam molded article has a thickness of 150 µm or less.   The thermoplastic pre-expanded particles have two melting peaks in the DSC curve obtained by differential scanning calorimetry, the heat of fusion α (J / g) of the low temperature side peak, and the heat of fusion β (J of the high temperature side peak) / G), the β / (α + β) value of the thermoplastic pre-expanded particles having an L / D of 0.8 or more and 1.2 or less is 0.15 or more and 0.35 or less, and the L / D is The thermoplastic resin foam molding according to claim 7 or 8, wherein the β / (α + β) value of the thermoplastic pre-expanded particles of 2 or more and 10 or less is 0.35 or more and 0.75 or less. Body manufacturing method.   The thermoplastic pre-expanded particles having an L / D of 0.8 to 1.2 are spherical pre-expanded particles, and the thermoplastic pre-expanded particles having an L / D of 2 to 10 are rod-shaped pre-expanded particles. Item 10. The method for producing a thermoplastic resin foam molded article according to any one of Items 7 to 9.   The thermoplastic resin foam molded article according to any one of claims 7 to 10, wherein the outer peripheral portion of the molded article has a porosity of less than 10%, and the other is constituted by a porosity of 10% or more and 60% or less. Manufacturing method.   The method for producing a thermoplastic resin foam-molded body according to any one of claims 7 to 11, wherein the foam-molded body is any one of an automotive raising material, a tibia pad, a luggage box, and a side projection material.

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