JPH06287337A - Abs resin foam - Google Patents

Abstract

PURPOSE:To obtain an ABS resin foam which has a relatively high expansion ratio and an excellent thermoformability. CONSTITUTION:An ABS resin foam is obtd. by foaming an ABS resin having a shear moduls (measured with a viscoelastic spectrometer at a frequency of 10Hz at 150 deg.C) of 1X10<4>-5X10<5> Pa with a blowing agent to an expansion ratio of 2-20. The foam, when compared with a polystyrene foam, has an excellent thermoformability and can deeply be drawn. The resulting thermoformed foam article is lightweight, has improved mechanical strengths, esp. impact strength. exhibits good cushioning and thermal insulating properties similar to those of a polystyrene foam, and is widely applicable, e.g. to a food container such as a cup and an automotive interior panel.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an ABS resin foam having excellent thermoformability.

[0002]

2. Description of the Related Art Conventionally, foamed products obtained by thermoforming sheet-shaped polystyrene foams have been widely used for food containers such as cups, internal panels of automobiles and the like.

This type of polystyrene foam does not have sufficient thermoformability. For example, when obtaining a deep-drawn foamed product having a drawing area ratio of about 2 times or more, the corner of the foamed product becomes thin. Torn. In addition, the polystyrene foam does not have sufficient mechanical strength, and the ends of the raw foam and the foamed product are easily cracked during molding or use.

On the other hand, ABS resin (acrylonitrile-butadiene-styrene copolymer) is superior in mechanical strength, particularly impact strength, to polystyrene resin.
A low foamed ABS resin (foaming ratio of about 1.3 to 2.5 times) is used as a structural material for doors, furniture and the like (see, for example, Japanese Examined Patent Publication No. 57-48380).

[0005]

As described above, the ABS is used.
The resin is tougher than the polystyrene resin. However, until now, ABS resin foams having a relatively high expansion ratio (expansion ratio of about 5 to 20 times), excellent thermoformability, and usable for food containers such as cups have been produced. , Not obtained.

Therefore, an object of the present invention is to provide an ABS resin foam which has a relatively high magnification and is excellent in thermoformability and has a wide range of uses such as food containers such as cups.

[0007]

The ABS resin foam of the present invention has a frequency of 10 Hz measured by a viscoelastic spectrometer.
Shear elastic modulus at 150 ° C. measured by 1 × 10 ^{4 to} 5
Made of × 10 ⁵ pascal ABS resin and has a foaming ratio of 5
˜20 times the ABS resin foam.

The ABS resin used in the present invention is a copolymer composed of three components of acrylonitrile, styrene and butadiene, and can be selected from known ABS resins.

In the present invention, the shear modulus at 150 ° C. is 1 × 10 ^{4 to} 5 × 10 ⁵ pascals, preferably 5 × 10 5.
ABS resin of ^{4 to} 2 × 10 ⁵ pascals is used. This shear modulus is the frequency 1 measured by a viscoelastic spectrometer.
It is a measured value at 0 Hz.

The reason why the shear modulus of the ABS resin is limited as described above is as follows. That is, 150 ° C
If the shear modulus at 1 is less than 1 × 10 ⁴ Pascal, one point of the foam will be too stretched during thermoforming and the corners of the foam product will be torn or become extremely thin, and conversely the shear modulus at 150 ° C will be 5 If it exceeds × 10 ⁵ Pascal, the foam will not be sufficiently expanded during thermoforming and cannot be shaped into a desired shape.

Further, in the present invention, the expansion ratio of the ABS resin foam is 5 to 20 times, preferably 8 to 18 times. The reason is that when the expansion ratio of the foam is less than 5,
This is because the foamed product lacks cushioning properties and heat insulation properties, and conversely, when the expansion ratio of the foam exceeds 20 times, the thermoformability of the foam will deteriorate.

Generally, the bubble diameter of the foam is preferably about 0.1 to 1 mm. If the bubble size of the foam is too small, the resin content of the bubble film will be small and the drawing area ratio at the time of thermoforming cannot be increased. Conversely, if the bubble size of the foam is too large, the foam Surface smoothness decreases.

When the foam has a large cell diameter, the resin content of the foam film increases, so that the shear modulus may be relatively low. Conversely, when the foam has a small cell diameter,
It is preferable that the shear modulus is relatively high.

In addition, the foam preferably has a closed cell ratio of 70% or more in order to improve the elongation during thermoforming. When the closed cell rate is low and the open cell rate is high, the foam is likely to be broken during thermoforming, and the change in thickness becomes large in accordance with the change in elongation, and the thickness of the corner portion of the foamed product becomes extremely thin.

The ABS resin foam for thermoforming of the present invention comprises:
Usually, it is in the form of a sheet. The thickness of the sheet varies depending on the thermoforming method, but generally 0.5 to 10 mm is preferable,
1 to 5 mm is more preferable. In addition, various sheets such as an ABS resin sheet and an elastomer sheet can be laminated on such a sheet-like foam.

To produce the ABS resin foam of the present invention, an extrusion foaming method and a batch foaming method are mainly adopted. In the extrusion foaming method, various additives are uniformly powder-mixed with an ABS resin by a tumbler or the like or pelletized, and the mixture or pellets are charged from a hopper of the extruder, and a gas provided in the middle of the extruder is used. The physical type foaming agent is press-fitted through the press-fitting hole to be dissolved in the ABS resin in the melt-kneaded state, and the extruded resin is foamed from the extrusion die.

When a pyrolyzable foaming agent is used as the foaming agent, the ABS resin, various additives and the pyrolyzable foaming agent are uniformly powder-mixed by a tumbler and the mixture is discharged from the hopper of the extruder. After being charged, the ABS resin is melt-kneaded in the extruder and the pyrolytic foaming agent is heated to decompose in the extruder, and the extruded resin is foamed from the extrusion die.

At this time, the resin temperature of the extrusion die is preferably set to a temperature higher by 20 to 50 ° C. than the softening temperature of the resin. The resin pressure at the extrusion die is, for example, 5 k in order to obtain a foam having a relatively high magnification and a high closed cell rate.
It is preferably g / cm ^{2 to} 20 kg / cm ² .

As the extruder, an extruder having a backflow prevention mechanism for preventing foaming gas from leaking to the rear of the extruder is used. Further, the tip of the die of the extrusion die is preferably made to have a low friction surface by, for example, applying Teflon coating or the like in order to prevent shear deformation of the resin.

In the batch foaming method, the ABS resin is molded into a desired shape such as a sheet or a block by a press or an extruder. This molded product is placed in a pressure vessel, filled with a physical type foaming agent, and heated to a softening temperature of the resin or higher and pressurized. After the physical foaming agent is sufficiently dissolved in the resin, the resin is foamed by setting the temperature higher than the softening point of the ABS resin by about 20 ° C to 50 ° C and reducing the pressure.

When a pyrolyzable foaming agent is used as the foaming agent, the crushed ABS resin and the pyrolyzable foaming agent powder are dry-blended with a Henschel mixer, a tumbler or the like to fill a mold of a desired shape with a press machine. Press with, AB
The heating is performed at the softening temperature of the S resin or higher and the decomposition temperature of the foaming agent or higher. When the foaming agent has decomposed sufficiently, the pressure is released and the resin is foamed.

As the physical type foaming agent, 1-chloro-
Low-boiling organic compounds such as 1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, 1,1-dichloro-1-fluoroethane, butane, pentane, carbon dioxide, nitrogen, etc. Inert inorganic gas is used.

As the thermal decomposition type foaming agent, one having a large amount of gas in the thermal decomposition and having a decomposition temperature of about 100 ° C. to 160 ° C. is used because the expansion ratio is relatively high.
For example, p, p′-oxybisbenzenesulfonyl hydrazide, calcium azide, ammonium acid salt, sodium bicarbonate, sodium borohydride and the like are used. An auxiliary agent may be added to these thermal decomposition type foaming agents in order to control the decomposition temperature.

In the present invention, in order to improve heat resistance, an ABS resin in which a monomer such as α-methylstyrene or N-phenylmaleimide is copolymerized is used as the ABS resin, or a resin having good compatibility is used. Blended A
BS resin can be used. Further, the ABS resin may be mixed with various additives such as an antioxidant, an ultraviolet absorber, an antistatic agent, a conductive material and a coloring agent.

To perform thermoforming using the ABS resin foam thus obtained, known vacuum forming methods, pressure forming methods,
A vacuum / pressure combined molding method and a press molding method are adopted. Particularly, when the drawing area ratio is large, the vacuum forming method is preferable.

The vacuum molding method includes a straight method in which a sheet-shaped ABS resin foam is heated and softened on a female mold to 140 to 170 ° C., and vacuum suction is applied to the mold to form a sheet-shaped ABS resin foam. There is a drape method or the like in which is heat-softened to 130 to 160 ° C. on a male mold, and the male mold is raised and vacuum suction is performed to mold the male mold.

[0027]

The ABS resin is superior to the polystyrene resin in mechanical strength, particularly impact resistance. And 150 ℃
Shear modulus at 1 × 10 ^{4 to} 5 × 10 ⁵ Pascal A
ABS made from BS resin and expanded 5 to 20 times
The resin foam exhibits excellent thermoformability because the shear modulus and the expansion ratio are in the appropriate ranges. In addition, the foamed product obtained by thermoforming exhibits good cushioning properties and heat insulating properties similar to polystyrene foam.

[0028]

EXAMPLES Examples and comparative examples of the present invention will be shown below. Example 1 ABS having a shear modulus of 2 × 10 ⁵ Pascal at 150 ° C.
Resin (Taflex TFX-220: Mitsubishi Monsanto Kasei Co., Vicat softening point 102 ° C., room temperature elongation 35%) 1
00 parts by weight and talc as a cell nucleating agent (average particle size 1
5 μm) 1 part by weight in the same direction twin-screw extruder (caliber 30 mm)
Was extruded at 220 ° C. to obtain a sheet having a thickness of 2 mm.

This sheet and carbon dioxide gas as a physical-type foaming agent were introduced into a pressure vessel and kept at 145 ° C. for 60 minutes at an internal pressure of 100 kg / cm ² . From this state, the pressure was released all at once to obtain a foamed sheet having a thickness of 5.2 mm.

The foamed sheet obtained had a foaming ratio of 18.6.
Doubled, the uniform and fine bubbles having an average bubble diameter of 0.1 mm had a closed cell ratio of 100%.

The shear modulus of the above ABS resin at 150 ° C. is determined by viscoelasticity spectrometer VES-F-III.
Using a mold (manufactured by Iwamoto Seisakusho), the measurement was performed at a frequency of 10 Hz. Further, the expansion ratio and the closed cell ratio of the foamed sheet were measured with an air comparison type hydrometer 1000 (manufactured by Tokyo Science Co., Ltd.).

Example 2 ABS having a shear modulus of 7 × 10 ⁴ Pascal at 150 ° C.
100 parts by weight of a resin (Styrac-ABS182: manufactured by Asahi Kasei Corp., Vicat softening point 120 ° C., room temperature elongation 40%) was roll-kneaded at 160 ° C., and a sheet having a thickness of 1.5 mm was formed by a press at 190 ° C.

This sheet and 1-chloro-1,1-difluoroethane as a physical type blowing agent were introduced into a pressure vessel, and 150
The container pressure was kept at 15 kg / cm ² for 30 minutes. The pressure is released all at once from this state, and the thickness is 4.6.
A foam sheet of mm was obtained.

The foamed sheet thus obtained had a foaming ratio of 19 times and had uniform and fine cells having an average cell diameter of 0.08 mm and a closed cell ratio of 100%.

Example 3 ABS having a shear modulus of 3 × 10 ⁵ Pascal at 150 ° C.
Resin (Taflex TFX-610: manufactured by Mitsubishi Monsanto Kasei Co., Vicat softening point 94 ° C., room temperature elongation 40%) 10
0 parts by weight and 7 parts by weight of p, p'-oxybisbenzenesulfonyl hydrazide powder as a thermal decomposition type foaming agent were dry blended with a tumbler.

This was filled in a sheet-like mold using a spacer having a thickness of 2 mm, and the press pressure was 300 kg / cm ² , 140 ° C.
In that state, the press pressure was released for 30 minutes to obtain a foamed sheet having a thickness of 3.2 mm.

The foamed sheet thus obtained had a foaming ratio of 6.2 times, uniform cells with an average cell diameter of 0.1 mm, and a closed cell ratio of 95.
%Met.

Example 4 100 parts by weight of the ABS resin used in Example 1 and 5 parts by weight of sodium bicarbonate powder as a thermal decomposition type foaming agent were dry blended in a tumbler.

This was filled in a sheet-shaped mold using a spacer having a thickness of 2 mm, and the pressing pressure was 300 kg / cm ² , 155 ° C.
In this state, the press pressure was released for 30 minutes to obtain a foamed sheet having a thickness of 4.3 mm.

The foamed sheet obtained had a foaming ratio of 12.3.
Doubled, it was a uniform cell with an average cell diameter of 0.15 mm and the closed cell rate was 100%.

Example 5 100 parts by weight of the ABS resin used in Example 1 and 1 part by weight of talc (average particle diameter 15 μm) as a cell nucleating agent were used at 230 ° C. in a twin-screw extruder of the same direction (diameter 30 mm). Was extruded into a rod shape and pelletized to obtain pellets.

The pellets were supplied to the hopper of a vent type extruder (bore diameter 65 mm, L / D = 35) set to 200 ° C., and carbon dioxide gas was supplied from the vent portion to 80 kg / cm ^2.
It was pressed in at a pressure of, and extruded into a sheet form from a mold (1 mm × 60 mm) set at 150 ° C. at a discharge rate of 15 kg / hr to obtain a foamed sheet having a thickness of 2.4 mm.

The foamed sheet obtained had a foaming ratio of 13.4.
Doubled, the uniform bubbles with an average bubble diameter of 0.3 mm have a closed cell ratio of 8
It was 0%.

Example 6 100 parts by weight of the ABS resin used in Example 2 and 1 part by weight of talc (average particle size 15 μm) as a cell nucleating agent were used in a twin-screw extruder of the same direction (diameter 30 mm) to give 230 parts. Pellets were obtained by extruding and pelletizing into rods at ℃.

The pellets were supplied to the hopper of a vent type extruder (bore diameter 65 mm, L / D = 35) set at 200 ° C., and 1,1,1,2-tetrafluoroethane of 50 kg was fed from the vent portion. 12 kg / hr by press-fitting at a pressure of / cm ²
With a discharge rate of 150 ° C (1 mm x 60 mm)
It was extruded into a sheet to obtain a foamed sheet having a thickness of 2.6 mm.

The obtained foamed sheet has a foaming ratio of 18.4.
Doubled, the uniform bubbles with an average bubble diameter of 0.4 mm have a closed cell ratio of 9
It was 0%.

Example 7 100 parts by weight of the ABS resin used in Example 3 and 15 parts by weight of p, p'-oxybisbenzenesulfonyl hydrazide powder as a thermal decomposition type foaming agent were dry blended with a tumbler.

This was kneaded with a twin-screw extruder in the same direction (diameter: 30 mm) at 180 ° C., and discharged at 19 kg / h at 145 ° C.
A foam sheet having a thickness of 3.8 mm was obtained by extruding into a sheet form from the mold (1.5 mm × 60 mm) set to.

The foamed sheet thus obtained has a foaming ratio of 12.0.
The ratio of closed cells was 75% with uniform cells having an average cell diameter of 0.55 mm.

Example 8 100 parts by weight of the ABS resin used in Example 3 and 15 parts by weight of calcium azide powder as a thermal decomposition type foaming agent were dry blended in a tumbler.

This was kneaded with a twin-screw extruder in the same direction (diameter 30 mm) at 180 ° C., and discharged at a rate of 22 kg / hr for 145
A foamed sheet having a thickness of 3.0 mm was obtained by extruding it into a sheet form from a mold (1.5 mm × 60 mm) set at ° C.

The foamed sheet thus obtained had a foaming ratio of 8.0 times, uniform cells having an average cell diameter of 0.9 mm and a closed cell ratio of 75.
%Met.

Comparative Example 1 ABS having a shear modulus of 8 × 10 ³ Pascal at 150 ° C.
Resin (Taflex YT-472: Mitsubishi Monsanto Kasei Co., Vicat softening point 93 ° C., room temperature elongation 30%) 100
Parts by weight and talc as a cell nucleating agent (average particle size 15 μ
m) 1 part by weight was used to obtain an extruded sheet at 220 ° C. by a twin-screw extruder in the same direction (diameter 30 mm).

This sheet and carbon dioxide gas as a physical-type foaming agent were charged into a pressure vessel and kept at 140 ° C. for 60 minutes at an internal pressure of 50 kg / cm ² . From this state, the pressure was released all at once to obtain a foamed sheet having a thickness of 4.1 mm.

The foamed sheet obtained had a foaming ratio of 10.8.
Doubled, the uniform and fine bubbles having an average bubble diameter of 0.1 mm had a closed cell ratio of 100%.

Comparative Example 2 100 parts by weight of the ABS resin used in Example 1 and 1 part by weight of talc (average particle size 15 μm) as a bubble nucleating agent were used in a twin-screw extruder of the same direction (diameter 30 mm) to give 230 parts. Pellets were obtained by extruding and pelletizing into rods at ℃.

The pellets were supplied to the hopper of a vent type extruder (bore diameter 65 mm, L / D = 35) set to 200 ° C., and 1,1,1,2-tetrafluoroethane 2 kg / It was pressed under a pressure of cm ² and extruded into a sheet form from a mold (2 mm × 60 mm) set at 150 ° C. at a discharge rate of 30 kg / hr to obtain a foamed sheet having a thickness of 2.8 mm.

The foamed sheet thus obtained had a foaming ratio of 4.2 times, uniform cells with an average cell diameter of 0.3 mm and a closed cell ratio of 10.
It was 0%.

Comparative Example 3 ABS having a shear modulus of 8 × 10 ⁵ Pascal at 150 ° C.
100 parts by weight of resin (Styrac-ABS185: Asahi Kasei Corp., Vicat softening point 138 ° C., room temperature elongation 20%) and 1 part by weight of talc (average particle size 15 μm) as a cell nucleating agent are biaxially extruded in the same direction. 23 depending on the machine (caliber 30 mm)
A foamed sheet was obtained by extruding at 0 ° C.

This sheet and carbon dioxide gas as a physical-type foaming agent were charged into a pressure vessel and kept at 170 ° C. for 60 minutes at an internal pressure of 50 kg / cm ² . From this state, the pressure was released all at once to obtain a foamed sheet having a thickness of 4.1 mm.

The foamed sheet obtained had a foaming ratio of 10.8.
Doubled, the uniform and fine bubbles having an average bubble diameter of 0.1 mm had a closed cell ratio of 100%.

Comparative Example 4 100 parts by weight of the ABS resin used in Example 1 and 1 part by weight of talc (average particle size 15 μm) as a cell nucleating agent were used in a same-direction twin-screw extruder (caliber 30 mmΦ) to give 230 parts. Pellets were obtained by extruding and pelletizing into rods at ℃.

The pellets were supplied to the hopper of a vent type extruder (bore diameter 65 mm, L / D = 35) set at 200 ° C., and 30 kg of 1,1,1,2-tetrafluoroethane was supplied from the vent section. 12 kg / hr by press-fitting at a pressure of / cm ²
With a discharge rate of 150 ° C (1 mm x 100)
It was extruded into a sheet to obtain a foamed sheet having a thickness of 2.9 mm.

The foamed sheet obtained had a foaming ratio of 25.8.
Doubled, the average bubble diameter is 0.2 mm, and the closed cell ratio is 9
It was 0%.

Evaluation of Thermoformability of ABS Foams Foamed sheets (length 1) obtained in each of the above Examples and Comparative Examples.
(50 mm × width 150 mm) was heated and softened at a predetermined temperature on a box-shaped female mold, and this was vacuum-sucked into the mold to form (drawing area ratio about 3).

The box-shaped female mold has a bottom and side walls with a thickness of 2
It has a recess of 0 mm, 100 mm in length × 100 mm in width × 50 in depth, R at the bottom four corners is 3 mmΦ, and vacuum suction holes are provided at four locations on the bottom.

Regarding the obtained box-shaped foamed product, the corner portion thickness, the corner portion thickness ratio (first foamed sheet thickness / corner portion thickness), and the corner portion cushioning coefficient C
The (minimum value) was measured, and the thermoformability was comprehensively evaluated based on this. The results are summarized in Table 1.

[0068]

[Table 1]

[0069]

As described above, the ABS for thermoforming of the present invention.
The resin foam has a frequency of 1 using a viscoelastic spectrometer.
Shear modulus at 150 ° C. measured at 0 Hz is 1 × 10
^{It is made} of ABS resin of ^{4 to} 5 × 10 ⁵ pascals and the expansion ratio is set to 5 to 20 times, whereby excellent thermoformability is obtained as compared with the conventional polystyrene foam.

Further, the foamed product obtained by thermoforming the above foam has improved mechanical strength, especially impact resistance, as compared with the one using a conventional polystyrene foam, and the polystyrene foam is used. It has good cushioning and heat insulating properties as well as the existing ones.

Therefore, the ABS resin foam for thermoforming of the present invention has a wide range of requirements such as food containers such as cups, interior panels of automobiles, lightweight, mechanical strength, cushioning and heat insulating properties. It can be suitably used for the production of foam products.

Claims (1)

[Claims] 1. A viscoelastic spectrometer for measuring frequency 1
Shear modulus at 150 ° C. measured at 0 Hz is 1 × 10
An ABS resin foam made of ^{4 to} 5 × 10 ⁵ pascal ABS resin and having an expansion ratio of 5 to 20 times.