JPH11198218A - Manufacture of foam body and foam body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a foam body having a skin layer consisting of minute cross linking polyorefin resin. SOLUTION: At a temperature of 200 deg.C or higher, placed in a kneading device are 100 pts.wt. polyolefin resin and a 0.1-10 pts.wt. multifunction monomer including two or more acryloyl oxy-groups or 0.05-5 pts.wt. dioxime having two oxime groups. Then, both of them are reacted in melt-admixture to thereby be modified into resin with improved tensile strength. The modified resin composition obtained is mixed with a foaming agent. Following this, obtained foaming resin composition is allowed of foam within a sizing mold. This manufacture produces a foamed body having a skin layer and with five times or more average expansion ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a foam, and more particularly to a method for producing a resin foam having a skin layer and a foam.

[0002]

2. Description of the Related Art In general, a foam having a skin layer as a surface layer is used as a heat insulating wall material, a heat insulating exterior material, a heat insulating back plate of a ceiling, and the like. A foam having a high expansion ratio has excellent heat insulating properties or cushioning properties, and those having a skin layer on the surface have excellent adhesive properties, decorative properties, and the like.

[0003] As a method of extruding such a foam, there is a method in which a highly foamable resin and a non-foamable or low-foamable resin are melted and multi-layer extruded. Japanese Patent Application Laid-Open No. Sho 59-70526 discloses that a mandrel having a trumpet-shaped opening at the center is disposed in a resin flow path of a mold.
A method of extruding a high foam having a skin layer with only a single foamable resin is disclosed. In this method, the resin that has passed through the trumpet-shaped opening forms the highly foamed layer of the core, and the resin that has passed through the slit on the outer periphery of the mandrel forms the skin layer.

[0004]

However, the method of melting a highly foamable resin and a non-foamable or low-foamable resin and extruding them in a multilayer manner complicates the structure of a molding die and requires two types of molding. Extruder is required, resulting in a problem that the equipment cost is high. In addition, there is a possibility that peeling may occur at the interface between the foam layer and the skin layer.

On the other hand, in the method disclosed in JP-A-59-70526, only a crosslinked resin can be used.
Normal non-crosslinked polyolefin resin has a tensile strength enough to pull the molded body against the frictional force generated by the sizing mold, even if a foam is obtained at the time of discharging from the extrusion mold. Because it is not in the foam, it cannot be continuously molded. In addition, the gel fraction is 20
% Of the crosslinked resin has too high a viscosity to be melted and flowed by a general screw extruder. As described above, there is a problem that only a special polyolefin resin having a limited gel fraction range can be used.

[0006] The gel fraction referred to herein means "after heating a crosslinked resin sample in xylene at 130 ° C for 24 hours,
Insoluble matter was separated by filtration through a 200-mesh metal net, then dried and weighed with a vacuum dryer at 80 ° C., and the weight percentage of the insoluble matter was obtained relative to the initial sample.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a method for continuously producing a polyolefin resin foam having a desired cross-sectional shape having a skin layer on a surface layer, and a foam thereof. It is.

[0008]

Means for Solving the Problems A method for producing a foam according to the invention of claim 1 is devised to achieve the above object, and comprises 100 parts by weight of a polyolefin resin,
0.1 to 10 parts by weight of acrylic polyfunctional monomer or 0.05 to 5 parts by weight of dioxime is melt-blended at 200 ° C. or more to modify the resin, and a foaming agent is mixed with the resulting modified resin composition. Then, after melt-kneading in an extruder, the mixture is shaped into a predetermined shape by an extrusion die, then discharged into a sizing die, and then foamed.

Examples of the polyolefin resin include polyethylene, polypropylene, ethylene-propylene copolymer resin, ethylene-vinyl acetate copolymer resin, ethylene-acrylic acid copolymer resin, ethylene-ethyl acrylate copolymer resin, polybutene, Ethylene-propylene-diene copolymer resin, chlorinated polyethylene,
Examples include polymethylpentene and the like.

The above-mentioned polyolefin resins may be used alone or in combination of two or more.
In the method of the present invention, particularly, polyethylene and / or polypropylene are preferably used.

The acrylic polyfunctional monomer is a compound having two or more, for example, 2 to 6, acryloyloxy groups.

Examples of the acrylic bifunctional monomer having two acryloyloxy groups include the following compounds.

Alkanediol diacrylate

Embedded image ・ Ethylene glycol diacrylate

Embedded image ・ Propylene glycol diacrylate

Embedded image ・ Polyethylene glycol diacrylate

Embedded image ・ Polypropylene glycol diacrylate

Embedded image ・ Neopentyl glycol diacrylate

Embedded image ・ Dimethylol tricyclodecane diacrylate

Embedded image ・ Diacrylate of ethylene glycol adduct of bisphenol A

Embedded image ・ Diacrylate of propylene glycol adduct of bisphenol A

Embedded image

Examples of the acrylic trifunctional monomer having three acryloyloxy groups include the following compounds.

Trimethylolpropane triacrylate

Embedded image ・ Pentaerythritol triacrylate

Embedded image ・ Trimethylolpropane ethylene oxide-added triacrylate

Embedded image ・ Glycerin propylene oxide added triacrylate

Embedded image ・ Trisacryloyloxyethyl phosphate

Embedded image

Examples of the acrylic tetrafunctional monomer having four acryloyloxy groups include the following compounds.

Pentaerythritol tetraacrylate

Embedded image ・ Ditrimethylolpropane tetraacrylate

Embedded image

Examples of the acrylic hexafunctional monomer having six acryloyloxy groups include the following compounds.

Dipentaerythritol hexaacrylate

Embedded image

The above-mentioned exemplified compounds of the acrylic polyfunctional monomer may be used alone or in combination of two or more.

The compounding amount of the acrylic polyfunctional monomer is 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polyolefin resin. If the amount is less than 0.1 part by weight, it is not possible to impart the tensile strength necessary to take up the foam. If the blending amount is 10
If the amount is more than 100 parts by weight, the acrylic monomer causes self-thermal polymerization, and the extension strength of the olefin resin does not increase. In addition, the ratio of the acrylic polyfunctional monomer remaining as an unreacted substance in the product increases, which irritates the human body and lowers the product efficiency with respect to the raw material.

Dioxime is an oxime group represented by the following formula:

Embedded image Or a structure in which a hydrogen group of an oxime group represented by the following formula is substituted with another atomic group (mainly a hydrocarbon group),

Embedded image Is a compound having two in the molecule, and examples thereof include the following compounds.

P-quinone dioxime

Embedded image ・ P, p'-dibenzoylquinone dioxime

Embedded image The above-mentioned compounds of dioxime can be used alone or 2
It may be used in combination of more than one kind.

The amount of the dioxime is 0.05 to 5 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the polyolefin resin. If the amount is 0.0
If the amount is less than 5 parts by weight, it is not possible to impart the required tensile strength to take up the foam. If the amount is more than 5 parts by weight, the degree of cross-linking will be too high and the extrudability will be poor. For example, there are problems such as a high load applied to the extruder and the occurrence of melt fracture in the molded product. In addition, the proportion of dioxime remaining as unreacted material in the product increases,
It irritates the human body and lowers product efficiency for raw materials.

In order to obtain a modified resin composition, a polyolefin resin and an acrylic polyfunctional monomer or dioxime are melt-mixed. Specifically, the above-mentioned two substances are charged in required amounts into a kneading device such as a screw extruder or a kneader, and are melt-mixed. The melt mixing temperature is 200 ° C. or higher and the decomposition temperature of the polyolefin resin or lower, preferably 2 ° C.
20 ° C to 300 ° C. When the melt mixing temperature is lower than 200 ° C., the reaction becomes insufficient, and a desired tensile strength may not be obtained or unreacted monomer may remain in the product. The expansion ratio of the foam finally obtained is not sufficiently high. On the other hand, when the temperature exceeds 300 ° C., the polyolefin-based resin is easily decomposed.

The kneading apparatus used for the melt kneading may be a screw kneader or a melt kneading apparatus which can be generally used in plastic molding.
Examples thereof include a rotor and a continuous kneader. Among them, 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 suitably used. As a single screw extruder, in addition to a general full flight screw, an extruder having a discontinuous flight screw, a pin barrel, a mixing head, and the like are also used. Further, as the twin screw extruder, a meshing co-rotating extruder, a meshing different direction rotating extruder, a non-meshing different direction rotating extruder and the like can be suitably used. Providing a vacuum vent at the latter stage of the extruder is effective for preventing volatiles from remaining in the resin composition.

When a screw extruder is used, the polyolefin-based resin is fed into the extruder from a usual hopper, but it is also preferable to use a screw type feeder, a weight control type feeder or the like in order to increase the quantitativeness.

The method of supplying the acrylic polyfunctional monomer or dioxime is not particularly limited. In the case of the acrylic polyfunctional monomer, for example, a method of simultaneously feeding the polyolefin resin from the hopper to the extruder, a method of feeding the polyolefin resin with the extruder Is supplied from a liquid injection hole provided in a downstream portion from a position at which the polyolefin resin is melted, and in particular, a pressure-feed pump such as a plunger pump is supplied from a liquid injection port provided after the position at which the polyolefin-based resin melts. The method of press-injecting the acrylic polyfunctional monomer is preferred because it can be uniformly dispersed in the molten resin.

In the case of a dioxime, for example, a method of dry-blending with an olefin resin and then charging the same in a hopper, a method of charging the olefin resin simultaneously with the olefin resin from a hopper using a quantitative feeder or the like, From the supply port using a side fader or the like.

The blowing agent may be either a thermal decomposition type chemical blowing agent or a physical type blowing agent. The thermal decomposition type chemical foaming agent is not particularly limited as long as it generates a decomposition gas by heating. Representative examples of the thermal decomposition type chemical blowing agent are azodicarbonamide and benzenesulfonyl hydrazide. These may be used alone or in combination of two or more. Among them, azodicarbonamide is particularly preferably used.

The physical foaming agent is not particularly limited as long as it is a volatile liquid or gas having a boiling point below the resin molding temperature. Representative examples of the physical foaming agents include aliphatic hydrocarbons such as butane and pentane, alcohols such as methanol and ethanol, 1,1-dichloro-1-fluoroethane, and 2,2-dichloro-1,1. , 1
Halogenated hydrocarbons such as trifluoroethane; carbon dioxide gas, nitrogen gas, and inorganic gases such as air.
These may be used alone or in combination of two or more.

The foaming agent is used in an appropriate amount in the range of 1 to 50 parts by weight, more preferably 2 to 35 parts by weight, based on 100 parts by weight of the modified resin composition, depending on the desired expansion ratio. Is preferred. If the amount of the foaming agent is less than 1 part by weight, the required expansion ratio cannot be obtained, and if it exceeds 50 parts by weight, the extension strength of the modified resin composition decreases, and the desired expansion ratio cannot be obtained.

Examples of the mode of obtaining a foamable resin composition by mixing a foaming agent with the modified resin composition include the following.

(A) A polyolefin resin and an acrylic polyfunctional monomer or dioxime are melt-mixed in a batch-type or continuous-type melt-kneading device for reforming, and the resulting modified resin composition is melt-kneaded in the same device. After solidification, granulation, etc., the same resin composition is transferred to a continuous kneading device for mixing a blowing agent, a blowing agent is charged therein, and both are melt-kneaded to form a foamable resin composition. Get things.

(B) A polyolefin resin and an acrylic polyfunctional monomer or dioxime are melt-mixed at a temperature of 200 ° C. or more in a reforming screw extruder (continuous melt kneading apparatus). A foaming agent is introduced from a supply port provided in the middle, and the two are melt-kneaded.

(C) In another form of continuous operation, 2
By connecting two screw extruders and the like, the first unit melt-mixes the polyolefin resin and the acrylic polyfunctional monomer or dioxime, and transfers the same resin composition to the second unit,
A foaming agent is added thereto, and the two are melt-kneaded.

The resin composition kneaded with the foaming agent is further shaped into a predetermined shape by an extrusion mold, and then discharged into a sizing mold to foam. When shaping, if the resin pressure in the mold is low, a high magnification may not be obtained. Therefore, it is preferable that the resin pressure in the mold is maintained at a pressure higher than the saturation dissolution pressure of the foaming gas in the molten resin.

The sizing mold is not particularly limited as long as it is a mold generally used in plastic molding and having functions of shaping and cooling, and is not particularly limited. A driver vacuum sizing die having a path and a decompression (vacuum) zone, a wet vacuum sizing die capable of shaping under reduced pressure while a refrigerant is in direct contact with a molded article, and the like are preferably used.

The flow paths of the extrusion mold and the sizing mold are appropriately designed according to the product shape, the expansion ratio, the take-up speed, and the like. (1) When the flow path of the sizing mold is enlarged in a similar manner to the flow path of the extrusion mold, the melt discharged from the extrusion mold foams uniformly outward in the sizing mold, The result is a foam having a thin skin layer over the entire surface.

(2) When the outer dimensions of the flow path of the sizing die and the flow path of the extrusion die are the same and the core is attached to the extrusion die, the melt discharged from the extrusion die has a hollow shape, Due to the restricted outer side, it foams inward in the sizing mold, resulting in a foam having a relatively thick skin layer over the entire surface.

(3) The upper surfaces of the flow path of the sizing die and the flow path of the extrusion die are flush with each other, and the flow path of the sizing die is enlarged below the flow path of the extrusion die. In this case, the melt discharged from the extrusion mold foams downward in the sizing mold, and as a result, a foam having a relatively thick skin layer on the upper surface is obtained.

If the distance between the extrusion die and the sizing die is too long, the skin layer will not be formed for the reason described later in the section of the operation, an appropriate distance in consideration of the expansion ratio and the size of the foam. Is determined.

If the surface temperature of the sizing mold is high, the skin layer is not fixed and bubbles may be gradually generated on the surface.

According to a second aspect of the present invention, there is provided a foam obtained by foaming a foamable resin composition obtained by mixing 1 to 50 parts by weight of a foaming agent with 100 parts by weight of the modified resin composition according to the first aspect. Further, the surface layer has a skin layer, and the average expansion ratio is 5 times or more. The blowing agent used in the second aspect of the invention may be either a thermal decomposition type chemical blowing agent or a physical type blowing agent.

The thermal decomposition type chemical foaming agent is not particularly limited as long as it generates a decomposition gas by heating. Representative examples of the thermal decomposition type chemical blowing agent are azodicarbonamide and benzenesulfonyl hydrazide. These may be used alone or in combination of two or more. Among them, azodicarbonamide is particularly preferably used.

The physical foaming agent is not particularly limited as long as it is a volatile liquid or gas having a boiling point below the resin molding temperature. Representative examples of the physical foaming agents include aliphatic hydrocarbons such as butane and pentane, alcohols such as methanol and ethanol, 1,1-dichloro-1-fluoroethane, and 2,2-dichloro-1,1. , 1
Halogenated hydrocarbons such as trifluoroethane; carbon dioxide gas, nitrogen gas, and inorganic gases such as air.
These may be used alone or in combination of two or more.

The foamable resin composition is the modified resin composition 10
The foaming agent is kneaded with 1 to 50 parts by weight with respect to 0 parts by weight. Preferably, it is used in an appropriate amount in the range of 2 to 35 parts by weight according to a desired expansion ratio. When the amount of the foaming agent is less than 1 part by weight, the amount of the foaming agent is small and a required expansion ratio cannot be obtained. On the other hand, if it exceeds 50 parts by weight, the extension strength of the modified resin composition will decrease, and a desired expansion ratio cannot be obtained.

The skin layer according to the second aspect of the present invention means an unfoamed surface layer that can be visually observed, and has an average expansion ratio of 5 times or more. If the average expansion ratio is less than 5, the foam cannot have sufficient heat insulating properties and cushioning properties. The average expansion ratio is JIS K-67.
It means the reciprocal of the apparent density measured according to 67.

(Function) According to the production method of the first aspect, the polyolefin resin undergoes a slight amount of crosslinking with the acrylic polyfunctional monomer or dioxime to modify the resin. The modified resin has an extensible strength that can be taken up against the frictional force generated in the sizing mold even when extruded and foamed.

When the modified molten resin is foamed and shaped into a predetermined shape by an extrusion die, and then cooled by a sizing die while taking the foam, the resin surface layer in a molten state is foamed into a resin inner layer. Contact the sizing mold with pressure remaining. Then, the air bubbles in the resin surface are crushed by the foaming pressure of the inner layer and simultaneously cooled. Then
An unfoamed surface layer is formed, and a foam having a high expansion ratio and having a skin layer on the surface layer is obtained. It should be noted that the skin layer becomes thicker as the molten resin is cooled before the growth of the foam has progressed so much.

[0051]

EXAMPLES (Example 1) (1) Step of preparing a modified resin composition A screw extruder shown in FIG. 1 was used as a melting and kneading apparatus for modification. In FIG. 1, 1 is a screw extruder, 2 is a forming die, 3 is a modified resin composition, 4 is a water tank, 5 is a pelletizer (granulator), 6 is a suction pump, 7 and 8 are thermocouples,
Reference numeral 9 denotes a feeder for resin, 10 denotes a feeder for dioxime comprising a fixed-quantity feeder, and C1 to C12 denote first to twelfth cylinder barrels. Next, the configuration of the screw extruder will be described in detail.

As the screw extruder 1, a TEX-44 type (manufactured by Nippon Steel Works) co-rotating twin-screw extruder was used. The L / D of the screw was 45.5. A strand die was used as the molding die 2, and a thermocouple for measuring resin temperature was used as the thermocouple 7 and the thermocouple 8. A suction vent comprising a suction pump 6 was installed in the ninth barrel in order to collect volatile components. The resin temperature measured by the thermocouple 7 installed between the eighth and ninth barrels was T1, and the resin temperature measured by the thermocouple 8 installed on the adapter part was T2.

Next, a method for preparing the modified resin composition will be described. The temperature in the screw extruder 1 was set as follows. The second to twelfth cylinder barrels are divided into four zones, the first zone is the second to fourth barrels, the second zone is the fifth barrel, the third zone is the sixth to twelfth barrels, and the fourth zone is the die and adapter part. And The temperature of the first barrel and each zone is as follows.
0 ° C, 220 ° C in the second zone, 220 ° C in the third zone,
The fourth zone was set at 220 ° C.

The screw speed was set to 100 rpm, and the polypropylene resin and dioxime were supplied from the hopper 13a to the first cylinder barrel C1 via the resin feeder 9 and the dioxime feeder 10, respectively.
As the olefin-based resin, a homopolymer of propylene (“EA8” manufactured by Mitsubishi Chemical Corporation, MI: 0.8, density: 0.1;
9 g / cm ³ ) and supplied at 14 kg / h. As the dioxime, p-quinone dioxime (p-QDO) was used, and 1.0 part by weight of dioxime was supplied to 100 parts by weight of the polypropylene resin. Thermocouple 7 and thermocouple 8
The resin temperature measured at 224 ° C. at T1 and 280 at T2
The resulting mixture was melt-mixed at a temperature of ° C. to obtain a modified resin composition 3. Then, the modified resin composition 3 was discharged from the molding die 2, cooled in the water tank 4, and then granulated by the pelletizer 5.

(2) Preparation of Foam As a kneading device for mixing a foaming agent and a mold for preparing a foam,
The screw extruder shown in FIG. 3 was used. In FIG. 3, reference numeral 14 denotes a screw extruder, 15 denotes a molding die which is an extrusion die, 1
6 is a driver vacuum die which is a sizing die, 17
Is a vacuum pump, 18 is a foam, 19 is a water tank, 20 is a take-off machine, 21 is a physical foaming agent tank, 22 is a plunger pump, 23 is a liquid injection nozzle, and C1 to C8 are first to eighth cylinder barrels. . Next, the configuration of the screw extruder will be described in detail.

As the extruder, an OSE-65 type (manufactured by Nagata Seisakusho) single screw extruder was used.
D was set to 35. A vertical die shown in FIG. 5 and an X-Y cross-sectional shape shown in FIG. 6 are used as an extrusion die, and a vertical cross-sectional shape shown in FIG. 5 is used as a sizing die and XY shown in FIG. Driver vacuum die 1 with cross-sectional shape
6 was used. The distance between the irregular die 15 and the driver's vacuum die 16 was 5 mm. A suction vent was installed in the fifth barrel to collect volatiles.

Next, a method for preparing the foamable resin composition will be described. The temperature in the screw extruder 14 was set as follows. The second to eighth cylinder barrels are divided into four zones, the first zone is the second to fourth barrels, the second zone is the fifth barrel, the third zone is the sixth to eighth barrels, and the fourth zone is the die and adapter part. And The temperature of the first barrel and each zone, the first barrel is always cooled, the first zone is 180 ℃,
The second zone was 180 ° C., the third zone was 180 ° C., and the fourth zone was 175 ° C.

The granulated modified resin composition 3 is transferred from the hopper 13b to the first cylinder barrel C using a quantitative feeder.
1 was fed at 20 kg / h. Physical foaming agent tank 21
The physical foaming agent inside was supplied from the liquid injection nozzle 23 to the fifth cylinder barrel C5 via the plunger pump 22. Monochlorodifluoroethane (CFC 142b) is used as a physical foaming agent, and the foaming agent is modified resin composition 1
13 parts by weight were supplied with respect to 00 parts by weight. The mixture was melt-mixed at a screw rotation speed of 30 rpm to prepare a foamable resin composition.

(3) Preparation of Foam The foamable resin composition obtained is extruded into a square shape by the core 26 of the profile die 15 shown in FIG. 5, and then connected to the adjacent vacuum pump 17. The foam was produced while cooling and depressurizing with the reduced pressure hole 28 and the driver vacuum die 16 provided with the water flow path 27. Then, it was passed through a water tank 19 and taken off by a take-off machine 20 to obtain a prismatic polypropylene resin foam 18.

(4) Physical Properties of Foam The expansion ratio (measured value of the specific volume of the foam sample) is 21 cc /
g. When the skin layer was visually confirmed, the skin layer was observed.

Example 2 (1) Step of Making Modified Resin Composition A screw extruder shown in FIG. 2 was used as a melting and kneading apparatus for reforming. In FIG. 2, 1 is a screw extruder, 2 is a forming die, 3 is a modified resin composition, 4 is a water tank, 5 is a pelletizer (granulating device), 6 is a suction pump, 7 and 8 are thermocouples,
11 is a liquid tank, 12 is a plunger pump, 13 is a liquid injection nozzle, 13a is a hopper, and C1 to C12 are first.
~ 12 cylinder barrels. Next, the configuration of the screw extruder will be described in detail.

As the screw extruder 1, a TEX-44 type (manufactured by Nippon Steel Works) co-rotating twin screw extruder was used. The L / D of the screw was 45.5. A strand die was used as the molding die 2, and a thermocouple for measuring resin temperature was used as the thermocouple 7 and the thermocouple 8. A suction vent comprising a suction pump 6 was installed in the ninth barrel in order to collect volatile components. The resin temperature measured by the thermocouple 7 installed between the eighth and ninth barrels was T1, and the resin temperature measured by the thermocouple 8 installed on the adapter part was T2.

Next, a method for preparing the modified resin composition will be described. The temperature in the screw extruder 1 was set as follows. The second to twelfth cylinder barrels are divided into four zones, the first zone is the second to fourth barrels, the second zone is the fifth barrel, the third zone is the sixth to twelfth barrels, and the fourth zone is the die and adapter part. And The temperature of the first barrel and each zone is as follows.
0 ° C., 170 ° C. in the second zone, 220 ° C. in the third zone,
The fourth zone was set at 220 ° C.

The screw rotation speed was set to 100 rpm, and a polypropylene resin was supplied from the hopper 13a to the first cylinder barrel C1.
The functional monomer was supplied from the liquid injection nozzle 13 to the fifth cylinder barrel C5 via the plunger pump 12. As the olefin-based resin, propylene homopolymer (“EA8” manufactured by Mitsubishi Chemical Corporation, MI: 0.8, density:
0.9 g / cm ³ ) and supplied at 14 kg / h.
Trimethylolpropane triacrylate (TMPTA) was used as the acrylic trifunctional monomer, and 2.0 parts by weight of the acrylic trifunctional monomer was supplied to 100 parts by weight of the polypropylene resin. Thermocouple 7 and thermocouple 8
The resin temperature measured at 220 ° C. at T1 and 274 at T2
The resulting mixture was melt-mixed at a temperature of ° C. to obtain a modified resin composition 3. Then, the modified resin composition 3 was discharged from the molding die 2, cooled in the water tank 4, and then granulated by the pelletizer 5.

(2) Preparation of Foam The same preparation as in Example 1 was performed using the same apparatus and method.

(3) Preparation of foam The foam was foamed in the same manner as in Example 1 to obtain a polypropylene resin foam.

(4) Physical Properties of Foam The foaming ratio (measured value of specific volume of foam sample) is 20 cc /
g. When the skin layer was visually confirmed, the skin layer was observed.

Example 3 (1) Step of Producing Modified Resin Composition The same apparatus and operating conditions as in Example 1 were used.

(2) Preparation of Foam As a kneading device for mixing a foaming agent and a mold for preparing a foam,
The screw extruder shown in FIG. 4 was used. In FIG. 4, reference numeral 14 denotes a screw extruder, 15 denotes a molding die which is an extrusion die, 1
6 is a driver vacuum die which is a sizing die, 17
Is a vacuum pump, 18 is a foam, 19 is a water tank, 20 is a take-off machine, 24 is a feeder for resin, 25 is a feeder for a thermal decomposition type chemical foaming agent, and C1 to C12 are first to twelfth cylinder barrels. Next, the configuration of the screw extruder will be described in detail.

An OSE-65 type (manufactured by Nagata Seisakusho) single screw extruder was used as an extruder.
D was set to 35. A vertical die shown in FIG. 5 and an X-Y cross-sectional shape shown in FIG. 6 are used as an extrusion die, and a vertical cross-sectional shape shown in FIG. 5 is used as a sizing die and XY shown in FIG. Driver vacuum die 1 with cross-sectional shape
6 was used. The distance between the irregular die 15 and the driver's vacuum die 16 was 5 mm. A suction vent was installed in the fifth barrel to collect volatiles.

Next, a method for preparing the foamable resin composition will be described. The temperature in the screw extruder 14 was set as follows. The second to eighth cylinder barrels are divided into four zones, the first zone is the second to fourth barrels, the second zone is the fifth barrel, the third zone is the sixth to eighth barrels, and the fourth zone is the die and adapter part. And The temperature of the first barrel and each zone, the first barrel is always cooled, the first zone is 180 ℃,
The second zone was 200 ° C., the third zone was 230 ° C., and the fourth zone was 180 ° C.

The granulated modified resin composition 3 is supplied from the hopper 13b to the first cylinder barrel C1 through the resin feeder 24 at a rate of 20 kg / h, and the thermally decomposable chemical foaming agent is supplied to the first cylinder barrel C1. It was supplied from the hopper 13b to the first cylinder barrel C1 via the feeder 25. Azodicarbonamide (ADC) as a thermal decomposition type chemical blowing agent
Using A), 12 parts by weight of a blowing agent was supplied to 100 parts by weight of the modified resin composition. Screw rotation speed 30rpm
m and melt-blended to obtain a foamable resin composition.

(3) Preparation of foam The foam was foamed in the same manner as in Example 1 to obtain a polypropylene resin foam.

(4) Physical Properties of Foam The expansion ratio (measured value of the specific volume of the foam sample) is 20 cc /
g. When the skin layer was visually confirmed, the skin layer was observed.

Example 4 (1) Step of Producing Modified Resin Composition The same apparatus as in Example 1 was used. For the preparation of the modified resin composition, the polypropylene resin used was a propylene random polymer (“EA8” manufactured by Mitsubishi Chemical Corporation, M
I: 0.8, density: 0.9 g / cm ³ ) except that the conditions were the same as in Example 1.

(2) Preparation of Foam The same procedure and the same operating conditions as in Example 1 were used.

(3) Preparation of foam The foam was foamed in the same manner as in Example 1 to obtain a polypropylene resin foam.

(4) Physical Properties of Foam The expansion ratio (measured value of specific volume of foam sample) is 20 cc /
g. When the skin layer was visually confirmed, the skin layer was observed.

Comparative Example 1 (1) Step of Forming Modified Resin Composition The same apparatus as in Example 1 was used. The adjustment of the modified resin composition was performed in the same manner as in Example 1 except that the supply amount of p-quinonedioxime was 0.02 parts by weight based on 100 parts by weight of polypropylene.

(2) Preparation of Foam The same apparatus and operating conditions as in Example 1 were used.

(3) Preparation of Foam The foam was not stretched enough to withstand the frictional force generated by the driver vacuum die 16 and was torn off in the middle of taking.

Comparative Example 2 (1) Step of Producing Modified Resin Composition The same apparatus as in Example 1 was used. The modified resin composition was prepared in the same manner as in Example 1 except that the supply amount of p-quinonedioxime was 6.0 parts by weight based on 100 parts by weight of polypropylene. At this time, the load of the extruder sharply increased, and melt fracture occurred in the melt discharged from the mold.

(2) Preparation of Foam The same apparatus and operating conditions as in Example 1 were used.

(3) Preparation of foam Since the expansion ratio of the foam after discharging the mold did not increase, the extruded product was taken at an extremely low take-off speed.

(4) Physical Properties of Foam The expansion ratio (measured value of the specific volume of the foam sample) is 4 cc / g.
Met. When the skin layer was visually confirmed, the skin layer was observed.

Comparative Example 3 (1) Step of Producing Modified Resin Composition The same apparatus as in Example 1 was used. The preparation of the modified resin composition was performed under the same operating conditions as in Example 1 except for the following conditions. Regarding the cylinder barrel set temperature, the first zone was 190 ° C., the second zone was 180 ° C., the third zone was 170 ° C., and the fourth zone was 170 ° C. The screw rotation speed was set to 40 rpm. Resin temperature measured by thermocouple 7 and thermocouple 8 is 180 ° C. at T1, 187 ° C. at T2
And

(2) Preparation of a Foam The same apparatus and operating conditions as in Example 1 were used.

(3) Preparation of Foam The foam had no tensile strength against the frictional force generated by the driver's vacuum die 16 and was torn in the middle of the pulling.

Comparative Example 4 (1) Step of Producing Modified Resin Composition The same apparatus as in Example 2 was used. The modified resin composition was prepared in the same manner as in Example 2 except that the supply amount of trimethylolpropane triacrylate (TMPTA) was 0.05 part by weight with respect to 100 parts by weight of polypropylene.

(2) Preparation of Foam A foam was produced using the same apparatus and operating conditions as in Example 2.

(3) Preparation of foam The foam had no tensile strength against the frictional force generated by the driver's vacuum die 16 and was torn off in the middle of taking.

Comparative Example 5 (1) Step of Producing Modified Resin Composition The same apparatus as in Example 2 was used. The modified resin composition was prepared in the same manner as in Example 2 except that the supply amount of trimethylolpropane triacrylate (TMPTA) was 12 parts by weight based on 100 parts by weight of polypropylene.

(2) Preparation of Foam A foam was produced using the same apparatus and operating conditions as in Example 2.

(3) Preparation of Foam The foam had no tensile strength against the frictional force generated by the driver's vacuum die 16 and was torn in the middle of the take-off.

Comparative Example 6 (1) Step of Producing Modified Resin Composition The same apparatus as in Example 2 was used. The modified resin composition was prepared under the same operating conditions as in Example 2 except for the following conditions. Regarding the cylinder barrel set temperature, the first zone was 190 ° C, the second zone was 180 ° C, the third zone was 170 ° C, and the fourth zone was 170 ° C. The screw rotation speed was set to 40 rpm. The resin temperature measured by the thermocouple 7 and the thermocouple 8 is 186 ° C at T1, and 188 ° C at T2.
And

(2) Preparation of Foam A foam was produced using the same apparatus and operating conditions as in Example 2.

(3) Preparation of Foam The foam had no tensile strength enough to withstand the frictional force generated by the driver's vacuum die 16 and was torn off during taking.

Comparative Example 7 An unmodified propylene homopolymer (“EA8” manufactured by Mitsubishi Chemical Corporation, MI: 0.8, density: 0.9 g / cm ³ ) was prepared without preparing a modified resin composition. )
It was used. Using the same apparatus as in Example 1, the preparation of the foamable resin composition was performed under the same operating conditions as in Example 1. The foamable resin composition was foamed, but was torn off during the take-off because the foam did not have sufficient tensile strength to take up the frictional force generated by the driver vacuum die 16.

Table 1 summarizes the operating conditions of Examples 1 to 4 and Comparative Examples 1 to 7 and the physical properties of the obtained foams.

[0100]

[Table 1]

[0101]

According to the first aspect of the present invention, the non-crosslinked resin maintains the melt fluidity to the extent that it can be kneaded and shaped with a foaming agent, and at the same time, the elongation to the extent that foaming is possible. Since a modified resin composition having strength can be obtained, a highly foamed olefin-based resin having a skin layer on the surface can be produced from a non-crosslinked resin using a sizing mold. In addition, a foam having excellent homogeneity and easily adjustable expansion ratio can be obtained.

Furthermore, the production equipment can be made less expensive than a multi-layer extrusion apparatus whose production equipment is expensive. Claim 2
Since the described invention is a foam having a skin layer at a high magnification, it is excellent in heat insulation or cushioning, and excellent in adhesiveness or decorativeness.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a screw extruder that can be charged with a dioxime and is used in a process of preparing a modified resin composition.

FIG. 2 is a schematic view showing a screw extruder that can be injected with an acrylic polyfunctional monomer and is used in a process of preparing a modified resin composition.

FIG. 3 is a schematic diagram showing a screw extruder that can be charged with a physical foaming agent and is used in a step of preparing a foamable resin composition.

FIG. 4 is a schematic view showing a screw extruder that can be charged with a thermal decomposition type chemical foaming agent and is used in a process of preparing a foamable resin composition.

FIG. 5 is a longitudinal sectional view of an extrusion mold and a sizing mold used to make a skin layer.

FIG. 6 is an XY cross-sectional view of an extrusion mold used to create a skin layer.

FIG. 7 is an XY cross-sectional view of a sizing mold used to create a skin layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw extruder 2 Molding die 3 Modified resin composition 4 Water tank 5 Pelletizer 6 Suction pump 7,8 Thermocouple 9 Resin feeder 10 Dioxime feeder 11 Liquid tank 12 Plunger pump 13 Liquid injection nozzle 14 Screw extruder 15 Extrusion Mold 16 Driver vacuum die 17 Vacuum pump 18 Foam 19 Water tank 20 Take-off machine 21 Physical foaming agent tank 22 Plunger pump 23 Liquid injection nozzle 24 Resin feeder 25 Pyrolytic type chemical foaming agent feeder 26 Core 27 Water flow path 28 Decompression hole

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 23/00 C08L 23/00 // (C08K 5/00 5: 103 5:29) B29K 23:00 105: 04 C08L 23: 00 (72) Inventor Yuji Okabe 2-2, Kamibahachochochocho, Minami-ku, Kyoto Sekisui Chemical Co., Ltd

Claims (2)

[Claims] 1. A polyolefin-based resin having 100 parts by weight,
0.1 to 10 parts by weight of acrylic polyfunctional monomer or 0.05 to 5 parts by weight of dioxime is melt-blended at 200 ° C. or more to modify the resin, and a foaming agent is mixed with the resulting modified resin composition. Then, after melt-kneading in an extruder, the mixture is shaped into a predetermined shape by an extrusion die, then discharged into a sizing die, and then foamed. 2. A foam obtained by foaming a foamable resin composition obtained by mixing 1 to 50 parts by weight of a foaming agent with 100 parts by weight of the modified resin composition according to claim 1, and having a skin on the surface layer. A foam having a layer and an average expansion ratio of 5 times or more.