JPH05338055A - Propylene foam sheet - Google Patents

Abstract

PURPOSE:To prevent the occurrence of uneven thickness in a molding by specifying the value of an average maximum thickness to an average minimum thickness that are obtained by measuring the thickness of a foam sheet along its width direction. CONSTITUTION:The value of the average maximum thickness to an average minimum thickness obtained by measuring the thickness of a foam sheet along its width direction Is made 0.9 or more. The basement resin is of the type that has long chain branches in its main chain. The propylene resin is made 60m/min. or below in the draw-down properties, and it is preferable that the seal-crystalization time in a crstalization temperature of +15 deg.C is 800sec. or more. In the case of using a tray-like vessel, e.g. a plate-like vessel having accommodation parts 2, 3 at both sides of a partition, or a vessel in which seal-spherical accommodation parts 5 are horizontally aligned in four rows and the positions of the accommodation parts 5 are aligned in upper and lower five rows to be shifted by half between the upper and lower rows, the drawing ratio in each accommodation part 3 is made 0.56. Thus, there never occurs any unevenness of thickness in a molding obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a propylene resin foam sheet.

[0002]

2. Description of the Related Art As a method for producing a long foam or a sheet foam for molding a container or the like, a thermoplastic resin is melt-kneaded with a foaming agent in an extruder and then subjected to low pressure. The extrusion foaming method of extruding and foaming is widely adopted.

In the extrusion foaming method of an olefinic resin, when a melt-kneaded product of a resin and a foaming agent is extruded from the extruder under a low pressure, the foaming agent in the melt-kneaded product expands to foam. However, when the temperature of the resin is raised, the viscosity drops sharply, and the resin cannot hold the foaming agent and escapes from the resin to become a foam of open cells. Conversely, the resin temperature must be increased to increase the viscosity of the resin. If it is lowered, the crystallization of the resin will proceed, and as a result, the foam will not foam sufficiently and uniformly, and the foam surface will become uneven. For this reason, the extrusion foaming needs to be carried out at a temperature at which the resin has sufficiently uniform foaming and has viscoelasticity capable of retaining the foaming agent in the resin. The temperature range in which viscoelasticity suitable for foaming is obtained differs depending on the type of resin, and this temperature range is generally called the foaming suitable temperature range.

[0004]

However, the viscoelasticity of the propylene resin, which has a higher degree of crystallinity than that of low density polyethylene and the like, greatly changes due to a slight temperature change, and the foaming suitable temperature range is very narrow. It is extremely difficult to carry out extrusion foaming while maintaining the resin temperature within such a narrow temperature range, and when the extrusion foaming temperature fluctuates and goes out of the foaming suitable temperature range, the foamed part has an open cell structure. However, it was difficult to obtain a foam having good and uniform properties as a whole. Conventionally, in the case of a non-crosslinked propylene-based resin, a relatively good foam can be obtained only when the density is a low expansion ratio of more than 0.2 g / cm ³ or when the density is 0.013 g / cm ^3. It has a high expansion ratio of less than.

The above-mentioned problems are considered to be caused by the high crystallinity of the propylene-based resin, and the density of the propylene-based resin is 0.
The reason why an extruded foam with a low expansion ratio of more than 2 g / cm ³ can be obtained relatively well is that the ratio of the resin is larger than the amount of the foaming agent. It is considered that this is because the temperature can be set to be considerably higher than that. The density is 0.013 g / cm ³
The reason why it is possible to obtain a foam having a high expansion ratio of less than 1 relatively well is as follows.

Generally, the olefin resin being foamed during extrusion foaming is subjected to an external cooling operation using a cooling means, thereby solidifying the cell walls to obtain a good foam. However, since propylene-based resin has a higher degree of crystallinity than low-density polyethylene, the amount of heat generated during crystallization is large. This heat hinders the cooling and thus the solidification of the cell walls, and destroys or deforms the cells of the propylene-based resin in the process of foaming.

Therefore, by foaming the foaming agent in a large amount, the heat of vaporization (expansion heat) of the foaming agent is used to drastically lower the temperature of the propylene resin during foaming, thereby solidifying the cell wall. Promote. Further, a large amount of foaming agent has a function of delaying the crystallization of the resin in the extruder. As a result, the foam can be obtained relatively well. However,
In this case, due to the necessity of blending a large amount of a foaming agent, the resulting foam will necessarily have a high expansion ratio with a density of less than 0.013 g / cm ³ . Also in this case, the temperature range suitable for foaming is only about 0.6 ° C.

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, by using a non-crosslinked propylene resin having a long chain branch and a drawdown property of 60 m / min or less as a base material, The applicant has found that a suitable foaming temperature range is wider than in the case of using a conventional non-crosslinked propylene resin as a base material, and that a foamed sheet having uniform and excellent properties can be obtained throughout the application (patent application 3-3550
No. 43).

Although this foamed sheet has an excellent appearance with less shrinkage and corrugation, it has a defect that thickness unevenness easily occurs in a molded product when vacuum molding or the like is performed. This thickness unevenness tends to increase as the degree of drawing of the molded product increases. Further, in the case of a sheet in which a non-foamed synthetic resin film is laminated on the surface of a foamed sheet, there is a problem that the laminated film is easily peeled off.

The inventors of the present invention have conducted extensive studies to find out the cause of uneven thickness in the molded product, and have confirmed that the cause is the presence of uneven thickness in the foam sheet.
Further, even if such a non-crosslinked propylene-based resin having a long chain branching and a drawdown property of 60 m / min or less is used as a base resin, extrusion foaming is carried out in the same manner as in the conventional method. It has also been found that it occurs when obtained.

The present inventors have found that uneven thickness occurs in a molded article using a foamed sheet having a long chain branch and a specific non-crosslinked propylene resin having a drawdown property of 60 m / min or less as a base material. In order to solve the problem, as a result of further diligent research going back to the cause of uneven thickness in the foamed sheet, as a result of devising the foaming conditions when using the above specific non-crosslinked propylene-based resin, the thickness of the foamed sheet can be improved. It is possible to obtain a foamed sheet in which the value of average minimum thickness / average maximum thickness when measured along the width direction is 0.9 or more. It was found that unevenness can be prevented as much as possible, and the present invention has been completed.

[0012]

Means for Solving the Problems That is, the propylene-based resin foamed sheet of the present invention is an extruded foamed sheet based on a non-crosslinked propylene-based resin having a long chain branch and a drawdown property of 60 m / min or less. The value of the average minimum thickness / average maximum thickness when the thickness of the foamed sheet is measured along the width direction is 0.9 or more.
In the foamed sheet of the present invention, the non-crosslinked propylene-based resin, which is the base resin, is particularly preferably a propylene-ethylene block copolymer.

The base resin constituting the foamed sheet of the present invention must have a long-chain branch in the main chain, unlike ordinary propylene resins. The propylene-based resin may be a homopolymer, a block copolymer, or a random copolymer, but a block copolymer is preferable,
A propylene-ethylene block copolymer is particularly preferable.

In the case of the copolymer, a copolymer of propylene and a small amount of olefin other than propylene is preferable, and examples of the olefin include ethylene and α-olefins having 4 to 10 carbon atoms. Two or more kinds can be used in combination. Examples of the α-olefin having 4 to 10 carbon atoms include 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3,4-dimethyl-1-butene, 1-heptene, 3-
Methyl-1-hexene and the like can be mentioned.

The above-mentioned α-olefin is usually contained in the copolymer in an amount of preferably 20% by weight or less, more preferably 10% by weight or less, and particularly 5% by weight or less when the α-olefin is ethylene. It is preferably contained in a ratio. The preferable lower limit of the content of these α-olefins in the copolymer is 0.5% by weight in any α-olefin. From the viewpoint of easy formation of long chain branches, a block copolymer is preferable to a random copolymer, and a propylene-ethylene block copolymer is particularly preferable.

The propylene-based resin used in the present invention is a normal crystalline linear propylene-based resin (usually having a weight average molecular weight of 100,000 or more), and the atactic content and / or the isotactic content is contained therein. A resin containing a non-crystalline component (hereinafter, this resin is referred to as a "normal propylene resin" in order to distinguish it from the propylene resin used in the present invention. (Which means a resin used in the invention) is mixed with a low-temperature decomposition type (decomposition temperature: room temperature to about 120 ° C.) peroxide and heated to 120 ° C. or lower, and atactic is added to the main chain of an ordinary propylene resin. Or / and can be obtained by a method of binding an uncrystallized isotactic component as a branched chain, and usually has a long chain branch mainly at the end. It believed to have a parting-like structure.

Examples of the low temperature decomposition type peroxide include di (s-butyl) peroxydicarbonate and bis (2-
Ethoxy) peroxydicarbonate, dicyclohexyl peroxydicarbonate, di-n-propylperoxydicarbonate, di-n-butylperoxydicarbonate, diisopropylperoxydicarbonate,
Examples thereof include t-butyl peroxy neodecanoate, t-amyl peroxy neodecanoate and t-butyl peroxypivalate.

The propylene-based resin, which is the base resin for the foamed sheet of the present invention, is the above-mentioned ordinary propylene-based resin which is stirred in a reactor equipped with a stirrer while the inside of the reaction vessel is replaced with an inert gas such as argon. Then, the above-mentioned peroxide is usually added in an amount of 5 to 50 mmol per 1 kg of the resin, and the mixture is heated to about 120 ° C., preferably about 70 to 105 ° C. while continuing stirring and reacted (usually 30 to 120 minutes). After that, it is obtained by stopping the reaction. In stopping the reaction, a reaction terminator such as methyl mercaptan is introduced into the reaction vessel, or the reaction product is heated at 130 to 150 ° C.
A method of heating for about 20 to 40 minutes or the like is adopted.

The propylene resin, which is the base resin of the foamed sheet of the present invention, has a drawdown property of 60 m / min or less, preferably 30 m / min or less, particularly preferably 15 m / min or less. This drawdown property means that the molten propylene-based resin heated to 230 ° C. is extruded into a string shape at a constant speed of 10 mm / min from a melt indexer nozzle (caliber 2.095 mm, length 8 mm), and then the string-like material. After passing through a feed roll located above the tension detecting pulley located below the nozzle, and then winding with a winding roll while gradually increasing the winding speed of the winding roll. And the winding speed of the string-like material at the time of cutting.

The drawdown property can be adjusted by the number and length of the long chain branches. Generally speaking, the greater the number of long chain branches and the longer the branch length, the lower this value tends to be. Therefore, in order to obtain a desired copolymer having a drawdown property, it is necessary to set the reaction conditions in consideration of these things. If there is no long chain branching, or if there are branching, it is too short or too little, or in the case of a normal propylene resin, the drawdown property exceeds 60 m / min. Even if such an ordinary propylene-based resin is used for extrusion foaming to obtain a foamed sheet having the same density of 0.3 to 0.06 g / cm ³ as the foamed sheet of the present invention, the obtained foamed sheet is There are many corrugations and surface irregularities, and the product has no commercial value.

The propylene resin used in the present invention preferably has a half-crystallization time at the crystallization temperature + 15 ° C. of 800 seconds or longer, and particularly preferably 1000 seconds or longer. A crystallization rate measuring device can be used for the measurement of the semi-crystallization time.

In order to measure the semi-crystallization rate, first, the support holding the film-like sample is placed in the air bath of the crystallization rate measuring instrument to completely melt the sample, and then the molten sample is put together with the support. Immersion in an oil bath maintained at the crystallization temperature of the sample + 15 ° C so as to block the optical path between the light source and the optical sensor, and always maintain a constant level in the optical sensor until the molten sample solidifies again. The voltage of the light source is adjusted so as to detect the light intensity of the above, and the voltage-time curve as shown in FIG. 1 is obtained. When the voltage when the voltage in this curve has a constant value is V ₀ , the time until the voltage becomes 1/2 V ₀ is the half-crystallization time.

In the present invention, not only the above propylene-based resin may be used alone, but also other resins may be mixed and used. As the resin to be mixed and used, for example, a propylene-based resin other than the above, high-density polyethylene, low-density polyethylene, linear low-density polyethylene,
Linear ultra-low density polyethylene, ethylene-based resins such as ethylene-butene copolymer, ethylene-maleic anhydride copolymer, butene-based resin, polyvinyl chloride, vinyl chloride-based such as vinyl chloride-vinyl acetate copolymer Examples thereof include resins and styrene resins.

When the other resin is mixed, the amount of the resin to be mixed is limited to 40% by weight of the total weight of the polymer after mixing, and the drawdown property of the mixture does not exceed 60 m / min. There is a need.

In the present invention, the above "average minimum thickness",
"Average maximum thickness" is calculated as follows. That is, at an arbitrary position of the foamed sheet, a cross section cut in the width direction of the sheet orthogonal to the longitudinal direction (extrusion direction) is sliced with a microtome, and a thick portion (peak portion) and a thin portion (valley portion) of the sheet are microscopically sliced. 10 each
The thickness was measured point by point, and the respective values were arithmetically averaged to obtain “average minimum thickness” and “average maximum thickness”.

The peaks and valleys are measured at arbitrary positions except 100 mm from both ends in the width direction of the sheet. However, the mountain part and the valley part are selected adjacent to each other. If the number of peaks and valleys at each measurement point is less than 10 points, the thicknesses of all the peaks and valleys that exist are measured, and the arithmetic average of each is calculated as "average minimum thickness" and "average maximum thickness". And

In the foamed sheet of the present invention, it is essential that the value of the average minimum thickness / average maximum thickness is 0.9 or more, but this value is preferably 0.95 or more. A foamed sheet having this value of less than 0.9 tends to have non-uniform heating during molding, and the thin portion of the sheet tends to become thinner during molding, resulting in uneven thickness in the molded product. In particular, in a sheet in which a non-foamed film is laminated, the laminated film is easily peeled off.

As a method for obtaining the propylene-based resin foamed sheet of the present invention, a non-crosslinked propylene-based resin having a long chain branch and a drawdown of 60 m / min or less is melt-kneaded in an extruder, A method in which this melt-kneaded product is attached to the tip of an extruder and a circular die having an annular lip is used to extrude foam from the lip of the die to obtain a tubular foam, and then the tube is cut open to form a sheet. Is usually adopted.

In this method, the resin flow passage area of the circular die is preferably reduced to half or less (narrowed) at one or more places, and further, a mandrel (cylindrical shape) for cooling the cylindrical foam extruded from the circular die. It is provided inside the tubular foam so as to cool from the inner surface side of the foam.) Cooling air is blown onto the outer surface of the tubular foam to cool the inner and outer surfaces of the tubular foam. The value of average minimum thickness / average maximum thickness is adjusted by adopting methods such as increasing efficiency, and adjusting the flow ratio, the temperature of the cooling air blown onto the outer surface of the tubular foam on the mandrel, and the amount blown. However, it is possible to obtain the foamed sheet of the present invention having 0.9 or more, preferably 0.95 or more.

It should be noted that the resin flow passage area of the circular die is preferably throttled in the vicinity of an intermediate portion of the die in the extrusion direction, and is expressed by the cross-sectional area of the resin flow passage in the throttle portion / the same cross-sectional area immediately before the throttle. It is desirable that the aperture ratio is 4 or more.
The cooling air on the mandrel is usually 10 to 5
The temperature is set to 0 ° C. and the flow rate is set to 0.3 to ³ m ³ / min.

As the foaming agent in the production of the foamed sheet of the present invention, an inorganic foaming agent, a volatile foaming agent, a decomposable foaming agent or the like can be used. Examples of the inorganic foaming agent include carbon dioxide, air and nitrogen.

Examples of the volatile foaming agent include propane, n-butane, i-butane, pentane, hexane and other aliphatic hydrocarbons, cyclobutane, cyclopentane and other cyclic aliphatic hydrocarbons, trichlorofluoromethane and dichlorodifluoromethane. , Dichlorotetrafluoroethane, methyl chloride,
Examples thereof include halogenated hydrocarbons such as ethyl chloride and methylene chloride.

Examples of the decomposition type foaming agent include azodicarbonamide, dinitrosopentamethylenetetramine, azobisisobutyronitrile, sodium bicarbonate and the like. These foaming agents can be appropriately mixed and used.

The amount of the foaming agent used varies depending on the type of the foaming agent, the desired expansion ratio, etc., but for obtaining the preferable density of the foamed sheet of the present invention, about 0.3 to 0.06 g / cm ³ , The amount of the volatile foaming agent used is about 0.5 to 6 parts by weight (converted to butane) of the volatile foaming agent per 100 parts by weight of the resin. Similarly, it is about 0.2 to 5 parts by weight (in terms of carbon dioxide) in the case of an inorganic foaming agent, and about 0.1 to 7.5 parts by weight in the case of a decomposition type foaming agent.

In the present invention, a cell regulator is added to the melt-kneaded product of the resin and the foaming agent, if necessary. Examples of the bubble control agent include inorganic powders such as talc and silica, acidic salts of polyvalent carboxylic acids, and reaction mixtures of polyvalent carboxylic acids with sodium carbonate or sodium bicarbonate. It is preferable to add about 13 parts by weight or less of the cell regulator per 100 parts by weight of the resin (except when a large amount of the inorganic filler is contained in the resin). Further, if necessary, additives such as a heat stabilizer, an ultraviolet absorber, an antioxidant and a colorant may be added.

Further, the resin may contain an inorganic filler up to 40% by weight of the total weight in advance. Examples of the inorganic filler include talc, silica, calcium carbonate, clay, zeolite, alumina, barium sulfate and the like. The average particle size of these is preferably 1 to 70 μm. When a large amount of such an inorganic substance is contained, the obtained foamed sheet has improved heat resistance and can reduce the calories burned during incineration.

The foamed sheet of the present invention usually has a thickness of about 0.1 to 3 mm and can be used as it is for molding, but it is used by laminating a non-foamed synthetic resin film on at least one surface. You can also Foamed sheets are vacuum-molded, pressure-molded, and their applications for heat-softened foamed sheets.
And ridge molding, ridge molding, matched molding, straight molding, drape molding, reverse draw molding, air slip molding, plug assist molding, plug assist reverse draw molding, etc. be able to. The foamed sheet of the present invention is particularly suitable for molding containers for microwave ovens, lunch boxes, automobile ceiling materials, automobile door interior materials, trunk room members and the like. It is also suitable as a core material for building materials.

[0038]

EXAMPLES The present invention will be described in more detail with reference to examples. In the examples and comparative examples, the amounts of the foaming agent and the cell regulator are added in% by weight when the total amount of these and the resin is 100% by weight. To measure the drawdown property and melt tension of the resin used, use a melt indexer,
Melt tension tester II manufactured by Toyo Seiki Co., Ltd.
The molds were used in combination, and a crystallization rate measuring instrument MK-801 manufactured by Kotaki Corporation was used for measuring the half-crystallization time.

The properties of the resins used in the examples and comparative examples are as follows.

Propylene resin A: Propylene / ethylene block copolymer having long-chain branch ("SD-632" manufactured by Highmont Co., USA: melting point 159.9 ° C, crystallization temperature 1)
30.1 ° C, semi-crystallization time 1353 seconds, MI = 2.0 g / 1
0 minutes, drawdown 3.1m / min, melt tension 1
3.0gf)

Propylene resin B: Propylene homopolymer having long chain branch ("PF-81" manufactured by Highmont Co., USA)
4 ”: melting point 159.0 ° C., crystallization temperature 127.4 ° C., semi-crystallization time 3220 seconds, MI = 2.2 g / 10 min, drawdown property 3.5 m / min, melt tension 17.4 gf)

Examples 1 to 6 and Comparative Examples 1 to 2 The resin, the foaming agent (isobutane) and the foam control agent (monosodium citrate) shown in Table 1 were mixed in the ratios shown in Table 1 in a tandem extruder (No. 1). Extruder: Screw diameter 65mm, L /
D = 34, second extruder: screw diameter 90 mm, L / D =
32) and melt-kneaded, then 65mmφ (die diameter) attached at the tip of the extruder, gap (lip clear) 0.5
It was extruded and foamed into a tube shape from a circular die of ˜1.5 mm (the resin flow passage area was narrowed in the vicinity of the middle portion in the die extruding direction. The drawing ratio was as shown in Table 1).

The extruded and foamed tubular foam was drawn so that its inner surface was in contact with a cooling mandrel (mandrel diameter 200 mm, set surface temperature 20 ° C.), and the temperature and flow rate shown in the same table on this mandrel were taken. This was blown onto the outer surface of the tube to cool it, and then the tubular foam was cut open in the extrusion direction to obtain a sheet. Extrusion conditions such as extrusion foaming temperature and the resulting foamed sheet (Production 1
Properties after 1 week) are also shown in Table 1.

In the comparative example, both the die diameter and the lip clear were the same as those of the circular die of the example, but a resin die in which the resin flow passage width was not narrowed in the vicinity of the opening of the die was used, and the resin was extruded into a tubular shape. The outer surface of the foam was not sprayed with cooling air on the mandrel.

[0045]

[Table 1]

* 1: "texture" of a foamed sheet means the number of bubbles per foamed sheet surface, 3 mm x 3 mm = 9 mm ² (cells / 9
mm ² ), and the number of bubbles was measured using a microscope.

Using the above sheet, a tray forming test and a deep drawing forming test were conducted under the following conditions.

[Tray Forming Test] Each sheet is clamped at approximately the center of a heating furnace having a heater of 50 W above and below (distance between heaters is 20 cm) and continuously guided and heated, followed by continuous plug-assisted vacuum forming. went. The target tray-shaped container is a dish-shaped container having storage portions 2 and 3 on both sides of the partition 1 as shown in FIGS. 2 and 3. In FIGS. 2 and 3, the dimensions a to h are: a: 175 mm, b: 112
mm, c: 63 mm, d: 110 mm, e: 90 mm, f: 40
mm, g: 30 mm, h: 25 mm. The presence or absence of thickness unevenness of the obtained molded product was judged according to the following evaluation criteria, and also shown in Table 1.

[Evaluation Criteria for Thickness Unevenness of Molded Article] The average minimum thickness / average maximum thickness of the molded article is measured in the same manner as the foamed sheet (however, the condition “excluding 100 mm from both ends in the width direction” is not included) is measured. ∘: 0.95 or more ∙: 0.9 or more, less than 0.95 Δ: ∙ 0.85 or more, less than 0.9 × ∙: less than 0.85

[Deep Drawing Test] Each sheet was clamped and guided to the approximate center of a heating furnace having a heater of 50 W (distance between heaters: 20 cm) at the top and bottom, and after heating, plug-assisted vacuum forming was continuously performed. It was The target molded product has a length of a = 453 mm and a width of b = 3 as shown in FIG.
In a foam sheet 4 of 00 mm, depth 45 mm, diameter: d =
The 80 mm hemispherical storage units 5 are arranged horizontally in four rows, and the storage units 5 are arranged in five rows so that the positions of the storage sections 5 are displaced by half between the upper and lower rows. Aperture ratio is about 0.5
It is 6. The presence or absence of thickness unevenness of the obtained molded product was judged by the same evaluation criteria as above, and the results are also shown in Table 1.

[0051]

As described above, the foamed sheet of the present invention has an average minimum thickness / average maximum thickness value of 0.9 or more when the thickness of the foamed sheet is measured along the width direction. As a result, when this foamed sheet is molded, there is no risk of uneven thickness occurring in the molded product, and even when a non-foamed film is laminated on the surface of the foamed sheet to form a laminated sheet, it is particularly noticeable when the sheet is molded. It is possible to prevent the occurrence of easy thickness unevenness and also prevent the peeling of the film, and it is possible to obtain an excellent molded product.

[Brief description of drawings]

FIG. 1 is a voltage-time curve obtained by crystallization rate measurement.

FIG. 2 is a plan view of a tray-shaped container formed by using the foamed sheets of Examples and Comparative Examples.

FIG. 3 is a side view of a tray-shaped container formed by using the foamed sheets of Examples and Comparative Examples.

FIG. 4 is a plan view of a deep-drawing molded product molded using the foamed sheets of Examples and Comparative Examples.

[Procedure amendment]

[Submission date] October 20, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

The propylene-based resin, which is the base resin for the foamed sheet of the present invention, is the above-mentioned ordinary propylene-based resin which is stirred in a reactor equipped with a stirrer while the inside of the reaction vessel is replaced with an inert gas such as argon. Then, the above-mentioned peroxide is usually added in an amount of 5 to 50 mmol per 1 kg of the resin, and the mixture is heated to about 120 ° C., preferably about 70 to 105 ° C. while continuing stirring and reacted (usually 30 to 120 minutes). After that, it is obtained by stopping the reaction. In stopping the reaction, a reaction terminator such as methyl mercaptan is introduced into the reaction vessel, or the reaction product is heated at 130 to 150 ° C.
A method of heating for about 20 to 40 minutes or the like is adopted. The
Whether long-chain branch exists in the molecular chain of ropylene resin
Can be confirmed by the following method. That is, extension flow
Measuring device (eg Rheometrics extensional flow measurement
Equipment: Propylene-based using the product name RER-9000)
A measurement sample is made from resin and the strain of this sample
Elongational viscosity (poise) at time (sec- ¹ ) and time
Graph the relationship with (seconds). Smell on this graph
The long-chain branch and the propylene-based resin
Propylene resin that does not include propylene resin
Ren resin has a large extensional viscosity curve with time.
However, with propylene-based resin that does not have long chain branching
Is the slope of the elongational viscosity curve smaller with time?
Can be distinguished. Above Rheometrics
Is it the measurement result by the long flow measuring device (RER-9000)?
A long-chain branched propylene-based resin and a long-chain branched
Elongational Viscosity of Strainless Propylene Resin at Strain Rate
The graph of FIG. 5 shows the relationship between degrees and time. Gu
Curve A in the rough shows a propylene resin with long chain branching.
The curve B shows a propylene-based resin having no long chain branching.
Show. From this graph, the propylene type with long chain branching
With resins, the slope of the extensional viscosity curve increases with time.
On the other hand, with propylene-based resin that does not have long chain branching
Shows that the slope of the elongational viscosity curve decreases with time.
I understand. The measurement sample and measurement conditions are as follows.
Is. ・ Measurement sample size and shape: length 30 mm, diameter 5
mm columnar ・ Strain rate: 1.0 sec- ¹ ・ Measurement temperature: melting point of base resin + 20 ° C (However, melting point is
Material resin 1 to 5 mg by differential scanning calorimeter at 10 ° C / min
Of the endothermic peak of the DSC curve obtained when the temperature is raised by
Temperature. )

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 5

[Correction method] Added

[Correction content]

FIG. 5 is a graph showing a relationship between elongational viscosity and time at a strain rate of a propylene resin having a long chain branch and a propylene resin having no long chain branch.

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Added

[Correction content]

[Figure 5]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area B29L 7:00 4F

Claims (2)

[Claims] 1. An extruded foam sheet having a long-chain branch and a drawdown property of 60 m / min or less as a base material, which is a non-crosslinked propylene-based resin, and the thickness of the foam sheet is measured along the width direction. A propylene-based resin foam sheet, wherein the average minimum thickness / average maximum thickness value is 0.9 or more. 2. The propylene-based resin foam sheet according to claim 1, wherein the non-crosslinked propylene-based resin is a propylene-ethylene block copolymer.