JP2014047252A - Polypropylene-based resin molded article and method for producing resin molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropylene-based resin molded article comprising a resin molded article having excellent mechanical properties and highly balanced flexibility and heat resistance and to provide a method for producing a resin molded article.SOLUTION: There is provided a polypropylene-based resin molded article comprising a resin molded article including 10 to 90 wt.% of a propylene-based polymer (A) and 10 to 90 wt.% of propylene-1-butene copolymer(B). The polypropylene-based resin molded article is obtained by a method for producing a resin molded article, the method comprising the steps of: (a) melting the resin composition into a molten state of 180°C or more; and (b) maintaining the resin composition at a holding temperature (T) which is lower than the melting point of the propylene-based polymer (A) by 20°C or more and is higher than the melting point of the propylene-1-butene copolymer (B).

Description

  The present invention relates to a polypropylene resin molded body produced by performing a specific heat treatment and a method for producing the resin molded body, and more particularly, a propylene-1-butene copolymer having a propylene resin and a specific comonomer content. The present invention relates to a polypropylene resin molded body comprising a resin composition having improved flexibility and heat resistance and having excellent mechanical properties by performing a specific heat treatment, and a method for producing the resin molded body.

Polypropylene resins are widely used in various molding fields because of their excellent mechanical properties and chemical resistance. In particular, taking advantage of the high rigidity and high heat resistance of polypropylene resin, it is widely used in various industrial products such as automobile interior and exterior and chemical containers.
Recently, demand for flexible polypropylene has been increasing in fields such as medical use and packaging. To soften polypropylene, for example, there is a method of forming a random copolymer by polymerizing a small amount of a comonomer typified by propylene and ethylene, but this is not sufficient, and for further softening, polypropylene can be used. In addition, techniques for blending ethylene-based elastomers such as ethylene-propylene copolymer rubber (EPR), styrene-based elastomers, and the like are often performed. Among them, a technique for finely dispersing ethylene-propylene copolymer rubber in polypropylene using a multistage polymerization technique is well known to those skilled in the art.

As described above, a softened polypropylene resin by blending a softer resin has high environmental compatibility (light weight reduction, recyclability, easy incineration, etc.) and is excellent in economic efficiency. It is used in a wide range of fields as sheets, fibers, nonwoven fabrics, various containers, molded products, modifiers, and the like.
However, in general, when ethylene-based elastomer, styrene-based elastomer or the like is blended with polypropylene, flexibility is obtained, but heat resistance is lost at the same time.

Under such circumstances, Patent Document 1 discloses a polypropylene composition containing polypropylene and a specific propylene-1-butene copolymer, which is excellent in flexibility and impact resistance and excellent in heat resistance and low-temperature heat sealability. ing.
However, Patent Document 1 does not describe specific numerical values with improved heat resistance, and does not disclose how to obtain a composition with excellent heat resistance.
Patent Document 2 discloses a propylene-ethylene-1-butene terpolymer having a specific monomer composition range, which has both transparency and flexibility, and a propylene-ethylene-1-butene terpolymer. A propylene-based resin composition with improved flexibility, including a propylene-based (co) polymer, is disclosed. According to Patent Document 2, it is shown that a butene copolymer is more compatible with a propylene resin than an ethylene elastomer.
However, the polymer and composition disclosed in Patent Document 2 are exclusively focused on improving flexibility and transparency, and no suggestion is made regarding a technique for improving heat resistance.

Conventionally, a technique for increasing the crystallinity by heat-treating a molded body in order to improve the performance of the polypropylene resin is known to those skilled in the art.
For example, Patent Document 3 discloses that a molded body containing polypropylene is heat-treated at 155 to 170 ° C. to improve rigidity, heat resistance, and hardness. Patent Document 4 discloses that a molded body of an olefin resin cooled to a temperature lower than the crystallization temperature is heated for 1 to 1,800 seconds at a temperature 2 to 10 ° C. higher than the melting temperature of the polyolefin resin, thereby being scratch resistant. Is disclosed. Patent Document 5 discloses that after forming polypropylene to obtain a molded body precursor, the molded body precursor is heated at 150 to 170 ° C. to improve rigidity and impact strength. Yes. Furthermore, Patent Document 6 discloses a method for producing a polypropylene molded body in which a polypropylene preform is heated at a temperature of (melting peak temperature −15 ° C.) to (melting peak temperature) and heat-treated.

Thus, when overviewing the performance improvement technology of polypropylene resin by conventional heat treatment, the heating temperature is approximately the melting temperature or near the melting temperature of polypropylene, and at the lowest, the melting temperature is about −15 ° C. Has been done.
However, the purpose of these heat treatment techniques is to increase the degree of crystallinity, and therefore the rigidity of the material is improved, and cannot be applied to materials in fields where flexibility is required. In addition, in the case of a composition rich in flexibility by blending a relatively large amount of the elastomer or the like with a polypropylene-based resin, heat treatment at a high temperature as in Patent Documents 3 to 6 performed on ordinary polypropylene. If it performs, there will also be a problem that a molded object will deform | transform greatly and a shape cannot be hold | maintained.

JP 2004-339523 A JP 2011-116972 A JP-A-62-279927 JP 2003-292649 A JP 2008-37102 A JP 2011-195830 A

When looking at the above prior art, there is a demand for higher flexibility for molded products made of a polypropylene resin composition for soft applications, but pursuing flexibility is a trade-off that generally loses heat resistance. There was a tendency, and improvement of this was desired.
Accordingly, an object of the present invention is to provide a molded article made of a resin composition having a high balance between flexibility and heat resistance and having excellent mechanical properties.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive studies. As a result, in producing a molded body from a resin composition having a specific ratio of a propylene-based polymer and a propylene-1-butene copolymer, By holding the resin composition at a specific temperature for a certain period of time, it has been found that a molded article having a high balance between flexibility and heat resistance and having high toughness can be obtained, and the present invention has been completed. It was.

That is, according to 1st invention of this invention, it consists of a resin composition containing 10 to 90 weight% of propylene-type polymers (A) and a propylene-1-butene copolymer (B). A polypropylene resin molded body,
A step (a) for bringing the resin composition into a molten state of 180 ° C. or higher; a melting temperature of the propylene-1-butene copolymer (B) which is 20 ° C. lower than the melting temperature of the propylene-based polymer (A); There is provided a polypropylene-based resin molded product obtained from the method for producing a resin molded product comprising the step (b) of maintaining at a higher holding temperature (T _Q ).

According to a second aspect of the present invention, in the first aspect, the polypropylene resin molding is characterized in that the butene content of the propylene-1-butene copolymer (B) is 10 to 50% by weight. The body is provided.
Furthermore, according to the third invention of the present invention, in the first or second invention, in the step (b), the holding temperature (T _Q ) is 62 to 140 ° C., and the holding time is 5 seconds or more. A polypropylene-based resin molded product is provided.

According to a fourth aspect of the present invention, there is provided a method for producing a polypropylene resin molded body according to any one of the first to third aspects,
A step (a) of bringing the resin composition into a molten state at 180 ° C. or higher;
The step (b) of holding at a holding temperature (T _Q ) lower than the melting temperature of the propylene-based polymer (A) by 20 ° C. or more and higher than the melting temperature of the propylene-1-butene copolymer (B),
A method for producing a polypropylene-based resin molded product is provided.

  The polypropylene-based resin molded body of the present invention has a remarkable effect that flexibility and heat resistance are highly balanced and also has high toughness.

In dynamic viscoelasticity measurement (DMA), it is an example (Example 1) of a measurement result of storage elastic modulus. In an Example, it is the figure which plotted the relationship between Young's modulus and heat-resistant temperature.

  Embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is an example of the embodiments of the present invention, and the present invention is not limited to the following unless it exceeds the gist. The description is not limited.

1. Polypropylene resin molded body The polypropylene resin molded body of the present invention (hereinafter sometimes simply referred to as a molded body) is composed of 10 to 90% by weight of a propylene polymer (A) and a propylene-1-butene copolymer ( B) A resin composition comprising 10 to 90% by weight is produced by subjecting it to a specific heat treatment.
The composition range of the propylene polymer (A) in the entire resin composition to be obtained is preferably 20 to 80% by weight, more preferably 30 to 70% by weight. Accordingly, the composition range of the propylene-1-butene copolymer (B) is preferably 20 to 80% by weight, more preferably 30 to 70% by weight. When the composition range of the resin composition is outside this range, the flexibility is insufficient or the heat resistance is insufficient, which is not preferable.

Here, as the propylene polymer (A), a propylene homopolymer or a propylene random copolymer obtained by copolymerizing propylene and a small amount of another comonomer is used.
Examples of the comonomer include ethylene and / or an α-olefin having 4 to 20 carbon atoms, and ethylene and 1-butene can be preferably used from the viewpoint of cost. Of course, multiple types of comonomers may be used simultaneously. The comonomer content is generally considered to be 10% by weight, preferably 5% by weight, and more preferably 3% by weight as the upper limit. When the comonomer content exceeds 10% by weight, the heat resistance of the entire molded article is lowered, and thus the gist of the present invention is not achieved.

Another resin component (B) of the resin composition constituting the molded article of the present invention is a propylene-1-butene copolymer.
Although the propylene-1-butene copolymer has high flexibility as disclosed in Patent Document 2 described above, other soft polyolefin resins, typically ethylene-propylene copolymers and ethylene -Higher compatibility with propylene polymers than ethylene-based elastomers such as butene copolymers.
In general, when an ethylene elastomer such as an ethylene-propylene copolymer or an ethylene-butene copolymer is blended with the propylene polymer (A), both of these are poorly compatible, so that a phase separation structure is formed. (For example, see "Journal of Applied Polymer Science" 1996, Vol. 62, p87.).

The formation of a phase separation structure leads to the formation of stress concentration points, and when the elastomer phase is relatively small, an effect of improving mechanical properties such as improved impact resistance can be obtained. As the elastomer content increases, the probability that the elastomer phases are bonded to each other to form a continuous phase increases, and then phenomena such as cohesive failure of the elastomer phase and interfacial delamination become prominent, resulting in heat resistance and tensile elongation at break. Such mechanical properties tend to decrease.
On the other hand, since the propylene polymer (A) and the propylene-1-butene copolymer (B) of the present invention are highly compatible, a clear phase separation structure cannot be confirmed with an electron microscope or the like. Even if the content of the propylene-1-butene copolymer is considerably increased, the mechanical properties are not deteriorated.

The preferable range of the butene content of the propylene-1-butene copolymer is 10 to 50% by weight (provided that the monomer fraction of the entire propylene-1-butene copolymer is 100% by weight). When the 1-butene content is less than 10% by weight, the flexibility is insufficient, and when the 1-butene content exceeds 50% by weight, the compatibility with the propylene polymer (A) is deteriorated. Absent. A preferred range for the 1-butene content is 15 to 45 wt%, more preferably 20 to 40 wt%.
Needless to say, the propylene-1-butene copolymer may contain a comonomer other than propylene and 1-butene without departing from the spirit of the present invention. Examples of the comonomer include α-olefins having 2 to 20 carbon atoms excluding propylene and 1-butene. The upper limit of the comonomer content is generally 10% by weight, preferably 5% by weight, and more preferably 3% by weight.

  In addition, although there is no restriction | limiting in particular about the range of MFR of a propylene-type polymer (A) and a propylene-1-butene copolymer (B), As an MFR range suitable for various shaping | molding uses, both are preferably 0.00. The range is 1 to 300 g / 10 minutes, more preferably 0.5 to 200 g / 10 minutes, and still more preferably 1 to 100 g / 10 minutes. The MFR is measured at a temperature of 230 ° C., a nominal load of 2.16 kg, a die shape diameter of 2.095 mm, and a length of 8.000 mm.

  Here, there is no restriction | limiting in particular as a manufacturing method of a propylene-type polymer (A) and a propylene-1-butene copolymer (B), It can manufacture using a conventionally well-known various method. For example, the polymerization catalyst may be produced using any conventionally known Ziegler-Natta catalyst, metallocene catalyst, etc., and the production method may be a conventionally known slurry polymerization method, bulk polymerization method, gas polymerization method, etc. Various combinations such as a phase polymerization method can be used.

The Ziegler-Natta catalyst is, for example, “Polypropylene Handbook” Edward P. Moore Jr. It is a catalyst system as outlined in Section 2.3.1 (pages 20-57) of the edited by Tetsuo Yasuda and Satoshi Sakuma, supervised by the Industrial Research Council (1998). For example, titanium trichloride and halogen A titanium trichloride catalyst composed of organoaluminum fluoride, a solid catalyst component essentially containing magnesium chloride, titanium halide, and an electron donating compound, a magnesium supported catalyst composed of organoaluminum and an organosilicon compound, and a solid catalyst component It refers to a catalyst in which an organoaluminum compound component is combined with an organosilicon treatment solid catalyst component formed by contacting organoaluminum and an organosilicon compound.
Preferable catalysts include, for example, a titanium trichloride composition obtained by reducing titanium tetrachloride with an organoaluminum compound and then treating with various electron donors and electron acceptors, an organoaluminum compound, and an aromatic carboxylic acid ester. (See JP-A-56-100806, JP-A-56-120712, JP-A-58-104907), magnesium tetrachloride, titanium tetrachloride and various electron donors. And the like (see JP-A-57-63310, JP-A-63-43915, and JP-A-63-83116) and the like.

  For the metallocene catalyst, see, for example, “Polypropylene Handbook” (edited by Edward P. Moore, Jr., Industrial Research Committee, 1998) pp. Several examples are described in 57-70. A typical example of the metallocene complex is a metallocene complex composed of a transition metal belonging to Group 4 of the periodic table (short-period type) having two bridged conjugated five-membered ring ligands. A so-called supported metallocene catalyst in which the metallocene complex is supported on solid particles can also be used. Specific examples of the structure of the metallocene catalyst include those disclosed in Japanese Patent Application Laid-Open Nos. 2005-132979 and 2007-224267.

2. Method for Producing Polypropylene Resin Molded Article A technique for producing a molded article from the resin composition of the propylene polymer (A) and the propylene-1-butene copolymer (B) of the present invention will be described in detail.
In order to produce a molded article having improved flexibility and heat resistance according to the present invention, after the step (a) of bringing the molten state to 180 ° C. or higher, it is 20 ° C. or lower lower than the melting temperature of the propylene-based polymer (A). After quenching to a temperature T _Q higher than the melting temperature of the propylene-1-butene copolymer (B), it is necessary to hold at that temperature (holding temperature T _Q ) for a certain period of time. In the present invention, a process for a predetermined time retained in the T _Q, and step (b).

In the present invention, a process for a certain time held at T _Q, is defined as a heat treatment. Surprisingly, through this heat treatment, from the resin composition of the propylene polymer (A) and the propylene-1-butene copolymer (B), the balance between flexibility and heat resistance of the molded product is remarkably increased. The inventors have found that this is improved.
In this case, the step (b) step (a), the should be continuously performed, at least, it is preferable that the transition temperature to the T _Q from 180 ° C. above the temperature of the molten state is monotonically decreasing In particular, it is necessary to consider not to be below the melting temperature of the propylene-1-butene copolymer (B) during the transition.

  In the step (a), it is desirable that the resin composition of the propylene-based polymer (A) and the propylene-1-butene copolymer (B) is in a completely molten state, and the melting temperature is preferably 190 ° C. or higher. More preferably, it is 200 degreeC or more.

As T _Q, it recommended specific temperature range is as follows.
Generally, in the case of a propylene homopolymer, the melting temperature is about 160 to 180 ° C., and in the case of a propylene random copolymer, it is about 130 to 160 ° C. In addition, a propylene-1-butene copolymer having a butene content of 10 to 50% by weight (7.69 to 42.86 mol%) is reported in “Macromolecules” 2011, Vol. 44, p540. as such, because it is generally 62 to 110 values of approximately ° C., _{T Q} is preferably in the range of from 62 to 140 ° C., more preferably 70 to 130 ° C., more preferably 75 to 120 ° C., most preferably 80 to 110 ° C. However, T _Q needs to be higher than the melting temperature of the propylene-based polymer used 20 ° C. or more below the melting temperature of (A), and propylene-1-butene copolymer (B).
In addition, the melting temperature of (A) and (B) in the present invention is determined by differential scanning calorimetry (DSC), and is melted from a temperature of 0 ° C. to 230 ° C. at a rate of temperature increase of 20 ° C./min. It is the peak temperature of the melting curve.

At T _Q, by holding a certain time, the reasons for improved balance between heat resistance and flexibility as a molded body, the present inventors have presumed as follows.
In _TQ , the propylene-1-butene copolymer (B) is melted, but the propylene polymer (A) starts to crystallize. Then, a part of the propylene-1-butene copolymer (B), possibly a relatively highly crystalline component, forms a co-crystal with the crystal part of the propylene-based polymer (A), thereby forming a resin composition. The crystallinity of the whole thing increases. Thereby, the heat resistance of a molded object improves.
On the contrary, in the propylene-1-butene copolymer (B), a low-crystal component that cannot form a co-crystal with the propylene-based polymer (A) is left, so that the elasticity of the remaining component itself is left. Since the modulus is suppressed to be lower than the elastic modulus of the entire original propylene-1-butene copolymer (B), a component having a lower elastic modulus exists in the molded body, and the crystal of the entire molded body Even if the property increases, the flexibility is not greatly impaired, and as a result, the balance between flexibility and heat resistance is improved.
Thus, the physical significance of T _Q, the propylene polymer (A) is crystallized, propylene-1-butene copolymer (B) alone is a temperature that does not crystallize. In general, the crystallization temperature measured by DSC of a propylene-based resin is about 20 to 40 ° C. lower than the melting temperature. This, T _Q is the reason necessary that the propylene polymer (A) 20 ° C. or higher than the melting temperature low.

The time for performing the heat treatment at T _Q is 5 seconds or more in order to ensure the time necessary for partial cocrystallization of the propylene-based polymer (A) and the propylene-1-butene copolymer (B). , more preferably 10 seconds or more, more preferably time than 1 minute, most preferably 3 minutes or more, is preferably maintained at T _Q. The upper limit is not particularly limited, but if it is too long, productivity deteriorates, so it is preferably 10 minutes or less, preferably 7 minutes or less.
As described above, in order for a part of the propylene polymer (A) and the propylene-1-butene copolymer (B) to form a cocrystal, the crystal systems of the two must be similar. This is another reason why the propylene-1-butene copolymer is used as the component (B).

3. Molding Method In the present invention, as a specific molding method, a conventional molding method in the polyolefin field can be used without particular limitation. Examples include injection molding, compression molding, various film moldings, sheet molding, rotational molding, blow molding, various fiber moldings, and the like.
In these moldings, a polyolefin resin, which is a normal raw material, is once melted and then molded into a desired shape using a mold or a die.
Therefore, it can be considered as a process (a) by making the temperature at the time of making resin into a molten state by these shaping | molding into 180 degreeC or more. The temperature in the molten state referred to in the present invention is usually the melting set temperature of the various molding machines exemplified above, for example, the temperature of a cylinder in the case of injection molding, the temperature of a die in film molding, sheet molding, and fiber molding. .
If it is known in advance that the actual resin temperature is clearly lower than the temperature of these cylinders or dies, the resin temperature is measured with a thermal sensor or the like so that the resin temperature becomes 180 ° C. or higher. It is preferable to adjust.

After the step (a), the temperature in the molten state is set to T _Q and the step (b) is performed. For this purpose, as long as various molding methods listed above, a roll and a belt controlled in T _Q or dies, etc., or by contacting the above predetermined time, the heating medium was controlled at T _Q or oven or the like It is achieved by passing through a predetermined time.
For also controls the T _Q, usually, roll, belt, mold, heating medium, but the set temperature of the oven can be regarded as T _Q, for example, Toka extremely faster line speed during film sheet molding, injection molding cycle time in circumstances short such, control of the resin temperature is not sufficient, the actual resin temperature be clearly higher than T _Q, if you know in advance, adjusted as appropriate machine temperature, step (B) It is preferable that the resin temperature be within the range of about T _Q ± 3 ° C. at the end.

Separately from the above method, even if it is a molded body obtained by a normal molding method without passing through the step (b), it is once melted at a temperature of 180 ° C. or more (step (a )), And holding it at _{TQ for} a predetermined time (step (b)), the effect of improving heat resistance can be obtained as in the case of molding by the above molding method.
In addition, when the molded body produced through the steps (a) and (b) is further subjected to secondary processing by vacuum molding or compression molding, the melting temperature of the propylene polymer (A) is set. It is preferable not to heat beyond that.

The resin composition of the propylene polymer (A) and the propylene-1-butene copolymer (B) to be used for molding may be blended in advance by various blending methods, or dry blended at a predetermined weight ratio. (A) and (B) may be put into a molding machine. Moreover, you may supply using a fixed quantity feeder etc. so that it may throw into a molding machine with a predetermined | prescribed weight ratio.
When the resin composition of the propylene polymer (A) and the propylene-1-butene copolymer (B) is blended in advance, it can be produced by various conventionally known blending techniques. Most commonly, a melt kneading method is used. For melt kneading, a single screw extruder, a twin screw extruder, a Banbury mixer, a roll mixer, a Brabender plastograph, a kneader, or the like is preferably used.

4). Use of Additives To the resin composition according to the present invention, in order to further enhance the performance of the resin composition according to the present invention, or to impart other performance, within a range not impairing the function of the present invention, Additives can also be blended.
As this additional component, a phenolic antioxidant, a phosphorus antioxidant, a sulfur antioxidant, a neutralizer, a light stabilizer, an ultraviolet absorber, a lubricant, a charge, which are widely used as a compounding agent for polyolefin resins. Various additives such as an inhibitor, a metal deactivator, a peroxide, a filler, an antibacterial agent, an antifungal agent, a fluorescent brightener, and a colorant can be mentioned.
In order to increase transparency and flexibility, general-purpose sorbitol-based nucleating agents, carboxylic acid metal salt-based nucleating agents, and phosphate metal salt-based nucleating agents are added so as not to lose the properties of the resin composition. Can be used together. Similarly, softening agents such as terpenes, rosins, mineral oils, waxes, natural resins and plasticizers can be used in combination.
The amount of these additives is generally 0.0001 to 3% by weight, preferably 0.001 to 1% by weight, based on 100% by weight of the resin composition.

5. Use of Other Resins In order to further enhance the performance of the resin composition according to the present invention or to impart other performance to the resin composition according to the present invention, the functions of the present invention are not impaired. Other resin materials can also be blended.
Examples of this additional resin component include LLDPE, LDPE, HDPE, ethylene elastomer, modified polyethylene, ethylene ethyl acrylate copolymer, modified polypropylene, polystyrene resin, polycarbonate, polyamide, Examples include modified PPE.
The amount of these resins is generally 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight with respect to 100 parts by weight of the resin composition.

6). Use of Molded Product The polypropylene-based resin molded product obtained by the method of the present invention can be suitably used in any field where polyolefin-based resins have been conventionally used. Examples include food containers such as trays, dishes, cups and lids, industrial materials such as automotive door trims, automotive trunk mats, bumper and other vehicle interior and exterior materials, as well as various packaging materials, stationery, It can be suitably used for building materials. In particular, the polypropylene resin molded body of the present invention is rich in flexibility and heat resistance, and among these uses, for fields requiring flexibility and heat resistance, for example, medical use requiring a sterilization process It can be particularly suitably used for the above-mentioned materials and food packaging materials premised on heating in a microwave oven.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples, unless the summary is exceeded.
In addition, the physical-property measurement used in the Example, each method of evaluation, sample preparation, etc. are as follows.

1. Physical property measurement and evaluation method (1) Melt flow rate (MFR):
According to JIS K7210A method and condition M, the measurement was performed under the following conditions.
Test temperature: 230 ° C., nominal load: 2.16 kg, die shape: diameter 2.095 mm, length 8.000 mm. The unit is g / 10 minutes.

(2) Melting temperature (Tm):
The measurement was performed using “Diamond DSC” manufactured by PerkinElmer. The melting temperature is defined as the peak temperature of the melting curve when melted at a temperature rising rate of 20 ° C./min from 0 ° C. to 230 ° C.

(3) Tensile test:
The tensile tester “Model 4466” manufactured by Instron was used. The dumbbell shape was 5 mm distance between gauges and 1 mm width.
The tensile speed was 10 mm / min, the test temperature was 25 ° C., and the Young's modulus, which is an index of flexibility, and the fracture strain, which is an index of toughness of the material, were evaluated.
The Young's modulus was obtained by approximating the stress-strain curve with a straight line within a strain of 0.015 or less. The breaking strain is a strain when the sample is finally broken. The strain is a nominal strain obtained as (L−L0) / L0 from the inter-gauge distance L of the stretched sample and the initial inter-gauge distance L0.

(4) Dynamic viscoelasticity measurement (DMA):
By using a dynamic viscoelasticity measuring device “DVE-V4” manufactured by Rheology Co., Ltd., by measuring the phase difference between the load and strain when applying a sinusoidal strain with a frequency of 10 Hz, Calculated.
The measurement temperature range was measured from −120 or −65 ° C. to melting. The test pieces were cut into strips having a width of 5 mm and a length of 30 mm, and the measurement was performed with an initial chuck distance of 20 mm.
During the measurement, a static load of 25 g was applied using the automatic static load function of the apparatus.
FIG. 1 shows an example of the measurement result. As shown in FIG. 1, in order to obtain the temperature at which the temperature dependence of the storage modulus suddenly changes in the region of a temperature of 100 ° C. or higher, the temperature dependence of the storage modulus before and after that is visually determined by two straight lines. The temperature at which the inclination changes greatly was determined as a point where the two lines intersect, and this temperature was defined as the heat resistant temperature.

2. Samples In Examples and Comparative Examples, propylene homopolymers, propylene-1-butene copolymers, and ethylene-butene copolymers having the following characteristics were used as samples.
(1) Component (A) propylene polymer (A):
Propylene homopolymer (PP); MFR = 10 g / 10 min, Tm = 163 ° C.
(2) Elastomer of component (B):
Propylene-1-butene copolymer (PBR); MFR = 7 g / 10 min, 1-butene content = 30 wt%, Tm = 73 ° C.
Ethylene-butene copolymer (EBR); MFR = 6.5 g / 10 min, Tm = 40 ° C., density = 0.86 g / cm ³

[Example 1]
The PP pellets and the PBR pellets were dry blended at a weight ratio of 40:60, and kneaded using “Micro Twin Screw Compounder” (15 cc) manufactured by DSM. The kneading conditions are a barrel set temperature of 180 ° C., a screw rotation speed of 40 RPM, and a kneading time of 5 minutes.
The recovered resin was sandwiched with a thin aluminum plate having a thickness of 100 μm and press-molded with a desktop hot press machine manufactured by Techno Supply. The press was performed under the conditions of preheating at 230 ° C. for 5 minutes and then maintaining at 230 ° C. for 1 minute under a pressure of 20 MPa. In the press, an aluminum spacer was used and the thickness was adjusted to about 200 μm. After pressurizing and pressing, each mold was immediately put into a hot water bath adjusted to 100 ° C. (T _Q ) and left for 5 minutes. Thereafter, the mold was removed from the hot water bath and allowed to cool at room temperature, and then the sample was peeled off from the aluminum plate to obtain a resin sheet.
From this sheet, a test piece cut into a dumbbell shape was used for tensile measurement, and a test piece cut into a strip shape was used for dynamic viscoelasticity measurement to obtain various physical property values. The results are shown in Table 1.

[Example 2]
In Example 1, it implemented like Example 1 except having set the compounding ratio of PP and PBR to 60:40. The results are shown in Table 1.

[Comparative Examples 1 and 2]
The PP and blending ratio of PBR, and as described in Table 1, and, except for changing the T _Q to 60 ° C. was prepared in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Examples 3 and 4]
The same procedure as in Example 1 was performed except that EBR was used instead of PBR and the blending ratio was changed as shown in Table 1. The results are shown in Table 1.

[Reference Examples 1 and 2]
The same operation as in Example 1 was carried out except that PP and PBR were each used alone. The results are shown in Table 1.
In addition, the heat resistance of PBR alone was extremely low, and it melted before 100 ° C., which could not be evaluated by the method shown in FIG. That is, the heat resistant temperature of PBR alone is less than 100 ° C.

[Consideration by comparison of Example and Comparative Example]
FIG. 2 shows plots in which the Young's modulus and heat-resistant temperature of Examples 1 and 2 and Comparative Examples 1 and 2 are respectively plotted on the horizontal axis and the vertical axis.
As is clear from FIG. 2, Examples 1 and 2 subjected to heat treatment at T _Q = 100 ° C. are more heat resistant in proportion to Young's modulus (flexibility) than Comparative Examples 1 and 2 at T _Q = 60 ° C. The temperature is remarkably improved.
In addition, although T _Q = 100 ° C., Comparative Examples 3 and 4 using EBR have an effect of improving heat resistance, but looking at the fracture strain which is the toughness of the materials, Examples 1 and 2 Compared with, it is inferior and the balance as a material is not good. This is presumed to be due to the fact that PP and EBR phases are phase-separated, so that EBR itself aggregates or breaks easily from the PP and EBR interface.
Further, Examples 1 and 2 have a good balance of physical properties that the flexibility and toughness are improved and the heat resistance is not greatly reduced even when compared with PP alone of Reference Example 1. Moreover, it turns out that heat resistance is improving dramatically, although a softness | flexibility falls compared with the PBR independent goods of the reference example 2. FIG.

  The polypropylene resin molded product of the present invention can be used in many applications where polyolefin resins have been used conventionally. Among these applications, fields requiring flexibility and heat resistance, for example, sterilization processes Can be used particularly suitably for medical materials that require heating, food packaging materials that are premised on heating in a microwave oven, and the industrial value is very high.

Claims (4)

A polypropylene resin molded body comprising a resin composition containing 10 to 90% by weight of a propylene polymer (A) and 10 to 90% by weight of a propylene-1-butene copolymer (B),
A step (a) for bringing the resin composition into a molten state of 180 ° C. or higher; a melting temperature of the propylene-1-butene copolymer (B) which is 20 ° C. lower than the melting temperature of the propylene-based polymer (A); A polypropylene-based resin molded article obtained from a method for producing a resin molded article comprising the step (b) of holding at a higher holding temperature (T _Q ).   The polypropylene resin molded article according to claim 1, wherein the propylene-1-butene copolymer (B) has a butene content of 10 to 50% by weight. The step (b) has a holding temperature (T _Q ) of 62 to 140 ° C. and a holding time of 5 seconds or more, The polypropylene resin molded article according to claim 1 or 2. It is a manufacturing method of the polypropylene resin molding according to any one of claims 1 to 3,
A step (a) of bringing the resin composition into a molten state at 180 ° C. or higher;
The step (b) of holding at a holding temperature (T _Q ) lower than the melting temperature of the propylene-based polymer (A) by 20 ° C. or more and higher than the melting temperature of the propylene-1-butene copolymer (B),
A method for producing a polypropylene-based resin molded product, comprising:

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