JP4832738B2 - Method for producing polyolefin resin foam sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyolefin-based resin foam excellent in impact resistance and rigidity, without causing problems, such as increase in a production cost and formation of an volatile organic compound (VOC). <P>SOLUTION: This polyolefin-based resin foam is formed out of a resin composition containing a modified polypropylene-based block copolymer, wherein the block copolymer is produced by modifying a polypropylene-based block copolymer having an MFR of &le; 5g/10 min and a propylene content of 85-99 wt%, in a molten and mixed state, with at least one kind of modifying monomer selected from a group consisting of a dioxime compound, a bismaleimide compound, an allyl-based polyfunctional monomer, an (meth)acrylic polyfunctional monomer, and a quinone compound. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a polyolefin resin foam, and more particularly, to a polyolefin resin foam using a modified polypropylene block copolymer having excellent impact resistance and rigidity and generating less volatile organic compounds.

Polyolefin resin foams such as polyethylene and polypropylene are excellent in lightness, heat insulation, flexibility and the like, and therefore are used for various heat insulation materials, cushioning materials, levitation materials, and the like. In particular, a polyolefin resin foam using a polypropylene resin has lightness, impact strength, rigidity, heat resistance, dimensional stability, and is used for automobile interior members, etc. Furthermore, both high impact strength and high rigidity for ensuring workability are required.
As such a polyolefin resin foam having high impact strength and rigidity, for example, a modified polyolefin resin foam obtained by modifying a polyolefin resin with a modifying monomer is disclosed (see, for example, Patent Documents 1 to 3). ). However, these polyolefin resin foams are mainly foams of modified products of homopolypropylene polymers and random polypropylene polymers, and polyolefin resin foams having excellent impact resistance and rigidity are still obtained. It wasn't. In order to obtain a polypropylene resin foam having such performance, it is considered that a foam of a polypropylene block copolymer is preferable, but the polypropylene block copolymer has a crosslinkability as compared with other polyolefin resins. Since it is inferior, a large amount of resin-modifying monomer is required, which causes problems such as an increase in production cost and generation of volatile organic compounds (VOC).
JP 11-291425 A JP 2001-38859 A JP 2002-120341 A

The object of the present invention is to produce a polyolefin resin foam sheet that solves the above-mentioned problems of the prior art, is excellent in impact resistance and rigidity, and does not cause an increase in production cost or generation of volatile organic compounds (VOC). It is to provide a method .

  As a result of intensive studies to solve the above problems, the present inventors have found that a modified polypropylene block copolymer obtained by modifying a polypropylene block copolymer having a specific MFR and propylene content with a specific modifying monomer is high. The inventors have found that a polyolefin-based foam having cross-linking reactivity, reduced additive monomers, and excellent impact resistance and rigidity can be obtained, thereby completing the present invention.

That is, according to the first invention of the present invention, a modification obtained by melt-mixing a dioxime compound and a polypropylene block copolymer satisfying the following characteristics (a) and (b) at a temperature of 200 to 250 ° C. Supply 100 parts by weight of polypropylene block copolymer, 1 to 500 parts by weight of unmodified polyolefin resin including polypropylene block copolymer and linear low density polyethylene, and heat decomposable chemical foaming agent to the extruder and melt A foamable resin composition is produced by mixing, the foamable resin composition is obtained by extruding the foamable resin composition from the extruder, and the foamable polyolefin resin sheet is decomposed with the foaming agent. There is provided a method for producing a polyolefin resin foam sheet characterized by heating at a temperature or higher.
(A) MFR is 5 g / 10 min or less (b) Propylene content is 85 to 99% by weight

According to the second invention of the present invention, in the first invention, with respect to 100 parts by weight of the polypropylene block copolymer in which the modified polypropylene block copolymer satisfies the above characteristics (a) and (b) , Provided is a method for producing a polyolefin resin foam sheet , which is obtained by blending 0.05 to 5 parts by weight of a dioxime compound .

  Since the present invention is a foam containing a modified polypropylene block copolymer obtained by reacting a polypropylene block copolymer with a specific modifying monomer, it has excellent impact resistance and rigidity, And it can be set as the polyolefin resin foam which suppressed generation | occurrence | production of a volatile organic compound (VOC).

  The present invention is a foam of a modified polypropylene block copolymer obtained by modifying a polypropylene block copolymer with a modifying monomer, and if necessary, another polyolefin may be added to the modified polypropylene block copolymer. Foam of the composition. This will be described in detail below.

1. Polypropylene block copolymer The polypropylene block copolymer used in the present invention is a block copolymer composed of a polypropylene polymer block and an α-olefin polymer block, or a polypropylene polymer block and an ethylene-propylene copolymer. Polypropylene-based two-components such as block copolymers composed of rubber blocks, copolymer rubber blocks composed of one or more rubbers selected from the group consisting of rubber, styrene-butadiene rubber and styrene-butadiene block copolymer Examples thereof include terpolymers and ternary copolymers. In these, the block copolymer containing a crystalline propylene polymer block and an ethylene-propylene copolymer block is preferable.

The polypropylene block copolymer used in the present invention must have the following characteristics (a) and (b).
(A) MFR
The MFR (melt flow rate) of the propylene-based block copolymer used in the present invention is 5 g / 10 min or less, preferably 0.4-2 g / 10 min. If the MFR exceeds 5 g / 10 min, the crosslinking property is remarkably lowered, which is not preferable.
Here, MFR is a value measured according to JIS K7210 (230 degreeC, 21.18N load).
(B) Propylene content The propylene content of the propylene-based block copolymer used in the present invention is 85 to 99% by weight, preferably 90 to 97% by weight. If the propylene content is less than 85% by weight, the crosslinkability is poor, and a large amount of a modifying monomer is required to give a sufficient viscosity for foaming. If it exceeds 99% by weight, the polypropylene block copolymer has a resistance to resistance. It becomes difficult to develop physical properties such as impact properties.
Here, the propylene content is a value measured by infrared spectrum spectroscopy.

2. The modifying monomer to be used in modifying monomer present invention is a compound having a functional group capable of radical reaction 2 or more, include dioxime compounds.
By modifying the polypropylene block copolymer using the above-described modifying monomer, the polyolefin resin has an appropriate foaming property even when the crosslink density is 20% or less without increasing the crosslink density as conventionally performed. Can be given to.

  Among the modifying monomers, the dioxime compound has an oxime group represented by the structural formula (1) or a hydrogen atom represented by the structural formula (2) substituted with another atomic group R (mainly a hydrocarbon group). A compound having two substituted oxime groups in the molecule, for example, p-quinonedioxime represented by Structural Formula (3), p, p-dibenzoylquinonedioxime represented by Structural Formula (4), etc. Is exemplified. A dioxime compound can also be used in combination of 2 or more type.

  The blending amount of the modifying monomer may be appropriately selected according to the type of the monomer, but is preferably 0.05 to 5 parts by weight, more preferably 100 parts by weight of the polypropylene block copolymer resin. 0.2 to 1.5 parts by weight. If the blending amount of the modifying monomer is less than 0.05 parts by weight, the melt viscosity necessary for foaming cannot be imparted, and if it exceeds 5 parts by weight, the crosslink density is excessively increased, and a high load is applied during extrusion. Fracture occurs and extrusion moldability deteriorates. Furthermore, the foaming agent added later cannot be uniformly kneaded into the resin composition, resulting in variations in gel fraction, foamability and physical properties. In addition, the foaming pressure at the time of heat foaming becomes too high, and a sheet-like material for suppressing foaming in the in-plane direction cannot be used with a low tensile strength.

  As a method of reacting the polypropylene block copolymer with the modifying monomer, a kneading apparatus such as a screw extruder or a kneader is usually used, and the polypropylene block copolymer and the modifying monomer are melted and reacted under predetermined conditions. . The reaction temperature at this time is 170 ° C. or higher and the decomposition temperature of the polyolefin resin or lower, preferably 200 ° C. to 250 ° C. If the reaction temperature is lower than 170 ° C., the modification is insufficient, and the foaming factor of the finally obtained foam may not be sufficiently high, and if it exceeds about 250 ° C., the polypropylene block copolymer tends to be decomposed.

  The apparatus used for the above reaction may be a melt kneader that can be generally used in plastic molding in addition to a screw extruder, and examples thereof include a kneader, a rotor, and a continuous kneader. Of these, a screw extruder capable of continuous operation is preferable, and a single screw extruder, a twin screw extruder, a multi-screw extruder having three or more screws, and the like are all preferably used. As a single screw extruder, in addition to a general full flight type screw, an extruder having a discontinuous flight type screw, a pin barrel, a mixing head, and the like are also used. As the twin screw extruder, a meshing same-direction rotating extruder, a meshing different-direction rotating extruder, a non-meshing different-direction rotating extruder, and the like can be suitably used. It should be noted that providing a vacuum vent at the subsequent stage of the extruder is effective in preventing volatiles from remaining in the resin composition.

  When a screw extruder is used, the polypropylene block copolymer is usually charged from the hopper into the extruder, but generally a screw feeder, a weight management feeder, or the like is used in order to increase the quantitativeness.

3. Other polyolefins In the polyolefin resin foam of the present invention, an unmodified polypropylene block copolymer is added to the modified polypropylene block copolymer for the purpose of improving strength, flexibility, moldability and foamability. And other polyolefin resins (hereinafter collectively referred to as blending resins) may be melt blended. By blending and using such a modified resin and a blending resin, the fluidity of the resulting foamable resin composition is improved, which makes it possible to form an extremely thin foamable sheet, resulting in a thin composite. A foam sheet can be produced. Further, the improvement in fluidity works favorably for forming spindle-shaped bubbles at the time of foaming, and as a result, a foam with higher compressive strength can be obtained.
The blending resins, and polypropylene-based block copolymer and linear low density polyethylene.

  The type and amount of resin used for blending depends on the moldability, appearance, adhesion to the sheet-like material, and the foaming ratio, mechanical properties, thermal properties, cell shape, etc. of the resulting foam. Adjust as appropriate. The amount of the resin for blending with respect to 100 parts by weight of the modified polypropylene block copolymer is preferably 500 parts by weight or less. When the amount of the resin for blending exceeds 500 parts by weight, the foaming property may be impaired, and the mechanical properties of the polypropylene block copolymer may not be sufficiently exhibited.

4). Foaming In the present invention, in order to obtain a foam, a foaming agent is added to the modified polypropylene block copolymer, and if necessary, a resin composition to which a blend resin is added. As the foaming agent, a thermal decomposition type chemical foaming agent is suitably used and is not particularly limited as long as it generates a decomposition gas by heating. Specific examples of the thermal decomposition type chemical foaming agent include azodicarbonamide, benzenesulfonyl hydrazide, dinitrosopentamethylenetetramine, toluenesulfonyl hydrazide, 4,4-oxybis (benzenesulfonyl hydrazide) and the like. These may be used alone or in combination of two or more. Of these, azodicarbonamide is particularly preferably used. The amount of the pyrolyzable chemical foaming agent is 1 to 50 parts by weight, preferably 2 to 35 parts by weight, depending on the desired foaming ratio with respect to 100 parts by weight of the modified polypropylene block copolymer-containing resin composition. And used in an appropriate amount.

  The foam of the present invention comprises a modified polyolefin resin, and the sheet thickness is usually 1 to 30 mm, preferably 2 to 10 mm. If the thickness is too thin, the rigidity and heat insulating properties are poor, and if it is too thick, heat shaping is difficult and shape transferability is poor. The expansion ratio of the foam sheet is determined depending on the application and the like, but is usually between 2 and 50 cc / g. If it is too small, the heat insulating properties and the like are lowered, and if too large, the mechanical strength such as rigidity is lowered.

  In order to obtain a foamable resin composition by kneading a pyrolytic chemical foaming agent, the above-described melt-kneading apparatus for reaction and a melt-kneading apparatus for mixing a foaming agent different from this (the structure is a melt for reaction) And may be the same as that of the kneading apparatus), and the both are mixed at a temperature not higher than the maximum temperature at which the foaming agent is not substantially decomposed. As an aspect of this melt-kneading, the following method is mentioned, for example.

(I) In a batch or continuous melt kneader for reaction, the polyolefin resin and the modifying monomer are melted and reacted, and the resulting modified resin is taken out of the melt kneader and solidified, granulated, etc. The resin composition is transferred to a batch type or continuous type kneading apparatus for mixing a foaming agent, and then the foaming agent is added thereto, and both are melt-kneaded to obtain a foamable resin composition.
(Ii) In a batch-type melt kneader for reaction, the polyolefin resin and the modifying monomer are melted and mixed to react, and the resulting modified resin is not substantially decomposed in the kneader. A method in which after cooling to temperature, a foaming agent is added thereto and both are melt-kneaded to obtain a foamable resin composition.
(Iii) In a reaction screw extruder (continuous melt kneader), the polyolefin resin and the modifying monomer are melted and mixed at a temperature of 170 ° C. or higher, and the resulting modified resin is treated with a blowing agent. A method of obtaining a foamable resin composition by lowering the temperature to a temperature that does not substantially decompose and then adding a foaming agent from a supply port provided in the middle of the screw extruder and melt-kneading both.
(Iv) In another form of continuous operation, two screw extruders or the like are connected, and the polyolefin resin and the modifying monomer are melted and mixed in the first unit, and the resulting modified resin is reacted. After the temperature is lowered in the same manner as described above, the resin composition is transferred to the second unit, a foaming agent is added thereto, and both are melt-kneaded to obtain a foamable resin composition.

A foamable resin composition obtained by kneading a pyrolytic chemical foaming agent in a mixture is shaped into a sheet. The method of shaping is especially, considering the productivity and the like and an extrusion molding method is preferable. For example, a method of continuously forming a sheet in an extruder using the foamable resin composition, or a foamable resin composition discharged from the extruder when the foamable resin composition is produced in an extruder The method etc. which make a thing a sheet directly are mentioned.

  The foamable sheet can be foamed to a desired foaming ratio under normal pressure or constant pressure by heating at an appropriate temperature condition according to the melt viscosity of the foamable sheet, the decomposition temperature of the foaming agent, and the like. In particular, as a continuous foaming device, in addition to a take-up type foamer that foams while taking out foam on the outlet side of the heating furnace, a belt-type foamer, a vertical or horizontal foaming furnace, a hot air thermostat, or an oil bath, metal Hot baths such as baths and salt baths are used.

In foaming, the foamable resin composition sheet can be foamed by laminating a polyethylene terephthalate (hereinafter abbreviated as PET) nonwoven fabric or the like. By foaming by sandwiching with a PET non-woven fabric or the like, the foaming magnification, the foaming direction, etc. can be controlled, and the foam can be given rigidity, mechanical strength and the like.
As the PET nonwoven fabric, long fibers by a spunbond method are usually used. PET long fibers are preferably used because they are richer in flexibility than glass fibers and have excellent shape compatibility during heat shaping.

  Since the polyolefin-based foam of the present invention uses a polypropylene-based block copolymer, it has excellent impact strength and rigidity, and the gel fraction of a polyolefin-based resin foam sheet that has been generally used conventionally is 40%. Compared with a foam mainly composed of a crosslinked polyolefin resin of a degree, a modified polyolefin resin having a gel fraction of 20% or less and a low crosslinking density is used. It has the effect of not causing cracks and the like during thermoforming.

  The present invention will be specifically described by the following examples and comparative examples, but the present invention is not limited to these examples. In addition, the measuring method of the physical property used by this invention is shown below.

(1) Propylene content: The propylene content in a predetermined propylene block copolymer was measured by infrared spectrum spectroscopy from a calibration curve of spectral intensity obtained using a resin having a known propylene content.
(2) MFR: Measured at 230 ° C. and 21.18 N load according to JIS K7210.
(3) Foam impact strength: Determined as 50% fracture energy at −30 ° C. measured according to JIS K7211.
(4) Foam flexural rigidity: Measured according to JIS K7221-2 and determined as an apparent elastic modulus.
(5) Gel fraction: The polyolefin resin foam original fabric is weighed, immersed in xylene at 120 ° C. for 24 hours, insoluble matter is filtered through a 200 mesh wire mesh, and the residue on the wire mesh is vacuum dried. The dry residue was measured and calculated by the following formula.
Gel fraction (% by weight) = (dry residue (g) / foam original fabric (g)) × 100
(6) Foaming ratio: It was determined as the reciprocal of the density measured according to JIS K7222.
(7) VOC (volatile organic compound) amount: VOC of foam is measured by measuring 9 substances of formaldehyde, acetaldehyde, toluene, xylene, ethylbenzene, styrene, dibutyl phthalate, tetradecane, diethylhexyl phthalate, all substances The foams that were below the standard values in Table 1 were regarded as passing VOC. The measurement of VOC was performed as follows.
(I) Collection of VOC After replacing a 10 L capacity Tedlar bag with pure nitrogen twice, a foam (8 × 10 cm) was sealed, filled with 4 L of nitrogen and heated in an oven at 65 ° C. for 2 hours. Thereafter, the total amount of gas (4 L) in the Tedlar bag was collected in a DNPH cartridge or Tenax-TA tube.
(Ii) Quantification of VOCs Among the VOCs, aldehydes were quantified by HPLC described below, and VOCs other than aldehydes were measured by GC-MAS.
(A) HPLC measurement The DNPH derivative was eluted with 5 ml of acetonitrile from the collected DNPH cartridge, and HPLC measurement was performed under the following conditions.
Pump: PU713 (GL Science)
Column: Inertsil ODS-3 (3.0 × 100 mm) (GL Science)
Column temperature: 40 ° C
Mobile phase: acetonitrile / water = 45/55 (v / v) 1.0 mL / min
Injection volume: 10 μL
Detector: UV detector (GL Science UV702) 360mm
(A) GC-MS measurement Using a Tenax-TA tube adsorbing VOC, GC-MS measurement was performed under the following conditions.
Thermal desorption device: ATD-400 (Perkin Elmer)
Sample heating: 250 ° C. (10 min)
Secondary desorption: 350 ° C., 10 min (15 ml / min) outlet split 1:10
GC-MS equipment: Automass II-15 (JEOL)
GC column: CP-SIL5CB (nonpolar) 0.32 mm × 60 m × 0.25 μm
GC temperature rise: 40 ° C (5min)-(5 ° C / min)-100 ° C-(10 ° C / min)-300 ° C
He flow rate: 1.5 mL / min
MS measurement range: 29-350amu
Ionization voltage: 70 eV
MS temperature: ion source; 230 ° C., interface; 250 ° C.

Example 1
(1) Equipment As a modification screw extruder, a BT40 (Plastics Engineering Laboratory Co., Ltd.) co-rotating twin screw extruder was prepared. This is equipped with a self-wiping twin screw, L / D is 35 and D is 39 mm. The cylinder barrel is composed of first to fourth barrels from the upstream side to the downstream side of the extruder, and a vacuum vent is installed in the fourth barrel to collect volatile components.
A TEX44 (manufactured by Nippon Steel Co., Ltd.) co-rotating twin screw extruder was prepared as a blowing agent kneading screw extruder. This is equipped with a self-wiping twin screw, L / D is 45.5 and D is 47 mm. The cylinder barrel is composed of first to twelfth barrels from upstream to downstream of the extruder, and the forming die is a T die having an exit width of 1100 mm. In order to supply the foaming agent, a side feeder is installed in the ninth barrel, and a vacuum vent is installed in the eleventh barrel to collect volatile components. A cooling roll device (manufactured by Sekisui Processing Co., Ltd.) comprising three rolls having a diameter of 220 mm and a width of 1250 mm was prepared as a sheet cooling and shaping device. A tandem type extrusion process was provided by connecting the tip of the BT 40 and the fifth barrel of the TEX 44, and the roll device was installed downstream thereof.

(2) Raw material As a polypropylene block copolymer, “Novatec PP EC9” (BPP: MFR = 0.5 g / 10 min, propylene content = 95 wt%, density = 0.9 g / cm ³ ) manufactured by Nippon Polypro Co., Ltd. The dioxime compound (“Barunok GM-P” manufactured by Ouchi Shinsei Chemical Co., Ltd.) was used as the modifying monomer.

(3) Modification of polypropylene block copolymer The polypropylene block copolymer was charged at 50 kg / h and the dioxime compound at 450 g / h from the feeder of BT40, both were melt-mixed and sent to the fifth barrel of TEX44. . At this time, the set temperature of the cylinder barrel of BT40 was 180 ° C. for the first barrel, 240 ° C. for the second to fourth barrels, and the screw rotation speed was 250 rpm.

(4) Mixing with unmodified polyolefin resin and foaming agent On the other hand, block polypropylene (Novatech PP BC3B manufactured by Nippon Polypro Co., Ltd., BPP: MFR = 9 g / 10 min, density = 0. 9 g / cm ³ ) and linear low density polyethylene (“Novatech LL UJ370” manufactured by Nippon Polypro Co., Ltd., LLDPE: MFR = 16 g / 10 min, density = 0.92 g / cm ³ ), respectively, 30 kg / h, 20 kg / h The mixture was poured and melted at h, and melted and kneaded with the modified polyolefin resin after the fifth barrel. Furthermore, azodicarbonamide (ADCA) was added as a blowing agent from the above side feeder at 7.5 kg / h, and this was melt-kneaded with the modified resin composition comprising the above-mentioned polyolefin after the ninth barrel. At this time, the cylinder barrel set temperature of TEX44 is constantly cooling the first barrel, 150 ° C for the second to fourth barrels, 170 ° C for the fifth to eighth barrels, 180 ° C for the ninth to twelfth barrels, and 160 ° C for the adapter and the die part. The screw rotation speed was 50 rpm.

(5) Shaping of the raw fabric sheet The foamable resin composition thus obtained is extruded from the T-die and passed through the three cooling rolls to obtain a polyolefin resin foamable sheet having a thickness of 0.4 mm. It was.

(6) Foaming operation Using a horizontal foaming machine (manufactured by Kyowa Engineering Co., Ltd.) with a total length of 6 m consisting of three zones: preheating zone, foaming zone and cooling zone, the preheating zone is 190 ° C, the foaming zone is 220 ° C, and the surface temperature of the cooling roll Was set to 90 ° C., respectively. When foaming the raw fabric sheet, in the preheating zone, a nonwoven fabric made of polyethylene terephthalate (“Syntex” 25 g / m ² made by Mitsui Chemicals) is sandwiched on both sides of the front and back surfaces of the foamable resin composition sheet. It was supplied to the foaming zone while fusing. The sheet supply rate was 0.5 m / min, the preheating and the residence time in the foaming zone were 8 minutes in total, and that in the cooling zone was 4 minutes. Thereby, a foam sheet having a good appearance was obtained from the outlet of the foaming machine. Table 2 shows the measurement results of the physical properties.

(Example 2)
In the raw material of Example 1 (2), the polypropylene block copolymer is “E-253G” (BPP: MFR = 1.4 g / 10 min, manufactured by Idemitsu Petrochemical Co., Ltd., propylene content = 95.5 wt%, density = Except for changing to 0.9 g / cm ³ ), the raw sheet was shaped and foamed in the same manner as in Example 1 to obtain a foam sheet with good appearance. Table 2 shows the measurement results of the physical properties.

(Comparative Example 1)
In the raw material (2) of Example 1, the polypropylene block copolymer was changed to a propylene random copolymer (RPP: “Novatech PP EG7” manufactured by Nippon Polypro Co., Ltd., MFR = 1.7 g / 10 min, density = 0.9 g. Except for changing to / cm ³ ), the raw sheet was shaped and foamed in the same manner as in Example 1 to obtain a foam sheet with good appearance. Table 2 shows the measurement results of the physical properties.

(Comparative Example 2)
In the raw material (2) of Example 1, a polypropylene block copolymer was made by Nippon Polypro Co., Ltd. “Novatech PP BC3B” (BPP: MFR = 9 g / 10 min, propylene content = 90 wt%, density = 0.9 g / cm Except for changing to ³ ), the raw sheet was shaped and foamed in the same manner as in Example 1, but a good foam was not obtained. Table 2 shows the measurement results of the physical properties.

(Comparative Example 3)
In the raw material (2) of Example 1, the polypropylene block copolymer is “INSPIRE112” (BPP: MFR = 0.5 g / 10 min, propylene content = 70 wt%, density = 0.9 g / manufactured by Dow Chemical Company. Except for changing to cm ³ ), the raw sheet was shaped and foamed in the same manner as in Example 1, but a good foam was not obtained. Table 2 shows the measurement results of the physical properties.

(Comparative Example 4)
In the raw material (2) of Example 1, the polypropylene block copolymer is “INSPIRE112” (BPP: MFR = 0.5 g / 10 min, propylene content = 70 wt%, density = 0.9 g / manufactured by Dow Chemical Company. cm ³ ), and in the modification of the polypropylene block copolymer of (3), the raw sheet was shaped and foamed in the same manner as in Example 1 except that the supply amount of the dioxime compound was 900 g / h. A foam sheet with good appearance was obtained. Table 2 shows the measurement results of the physical properties.

  The foam according to the present invention comprises a modified polyolefin resin obtained by reacting a polypropylene block copolymer with a modifying monomer, so that it has excellent impact strength and rigidity, and has an increased production cost and a volatile organic compound ( Since it does not cause the problem of occurrence of VOC), it can be suitably used for applications requiring high impact strength and workability.

Claims (2)

100 parts by weight of a modified polypropylene block copolymer obtained by melt-mixing a dioxime compound and a polypropylene block copolymer satisfying the following characteristics (a) and (b) at a temperature of 200 to 250 ° C. , a polypropylene block 1 to 500 parts by weight of an unmodified polyolefin resin containing a copolymer and a linear low-density polyethylene, and a thermally decomposable chemical foaming agent are supplied to an extruder and melt-mixed to produce a foamable resin composition. A polyolefin resin characterized in that a foamable polyolefin resin sheet is obtained by extruding a foamable resin composition from the extruder, and the foamable polyolefin resin sheet is heated above the decomposition temperature of the foaming agent. A method for producing a foam sheet .
(A) MFR is 5 g / 10 min or less (b) Propylene content is 85 to 99% by weight The modified polypropylene block copolymer is obtained by blending 0.05 to 5 parts by weight of a dioxime compound with respect to 100 parts by weight of the polypropylene block copolymer satisfying the above characteristics (a) and (b). The method for producing a polyolefin resin foam sheet according to claim 1, wherein: