JP5412024B2 - Propylene polymer composition - Google Patents

Description

  The present invention relates to a propylene-based polymer composition, and more specifically, a propylene homopolymer having a latent heat amount of 80 KJ / Kg or less by thermal analysis using a differential scanning calorimeter (DSC), or a propylene-based random or block copolymer. The present invention relates to a propylene component-rich polymer composition obtained by blending a specific amount ratio of ethylene / (meth) acrylic acid alkyl ester with a coalescence or the like.

  Polypropylene is a typical general-purpose plastic because it has a specific gravity of 0.87 to 0.91 and is light and relatively strong. It also has high resistance to chemicals and solvents and has excellent moldability. It is widely used from daily necessities to various packaging materials (films, containers) and industrial parts materials such as automobile bumpers.

  For polypropylene, an amorphous or so-called atactic polymer and an isotactic or syndiotactic polymer in which side chain methyl groups are regularly arranged in the same direction or in the opposite direction are known. Most of the industrially produced products are isotactic or syndiotactic polymers having high crystallinity and stereoregularity.

However, recently, it has become possible to relatively freely control the stereoregularity as well as the molecular weight, molecular weight distribution, etc., depending on the catalyst and polymerization method, and polymer design has become possible to some extent. It shows a tendency to expand to the field of fine parts such as micro gears.
In particular, in recent years, the use of chlorinated resin films and containers such as vinyl chloride and vinylidene chloride, which have a large environmental burden, tends to be avoided, so polyolefin resin films and containers such as polypropylene that have less environmental burden are often used. There is a growing tendency.

  Polypropylene, in particular its homopolymer, has a translucent to transparent appearance and has advantages such as excellent heat resistance such as a melting temperature (Tm) of 160 to 170 ° C., for example, a stretch food packaging film. Depending on the application, the rigidity is too high, the low molecular weight is inferior in toughness, and the glass transition point is near 0 ° C. there were.

Several attempts to improve the drawbacks of such polypropylene have also been proposed. For example, Patent Document 1 mainly includes a propylene component having a substantially syndiotactic structure, and a small amount of an ethylene component is copolymerized therewith. A soft syndiotactic polypropylene composition comprising a propylene / ethylene copolymer and a terpene resin or petroleum resin, and an invention of a film-modifying composition excellent in transparency, flexibility, heat resistance and wear resistance Is disclosed.
Patent Document 2 discloses a method for producing a flexible polypropylene having excellent heat resistance by polymerizing propylene or propylene and an α-olefin with a specific catalyst component comprising a specific transition metal compound, a promoter, and a polyene compound. Is disclosed.

Japanese Patent Laid-Open No. 2004-161974 Japanese Patent Laid-Open No. 08-301935

  Certainly, the resin or resin composition of the above-mentioned Patent Document 2 has sufficient flexibility and toughness up to a temperature near 15 ° C. below zero, and has an attribute that can be used for packaging films and the like. When placed under a freezing temperature lower than about 20 ° C., stiffening and embrittlement are inevitable, and the low-temperature characteristics are not necessarily sufficient.

The present inventors have made extensive studies to improve the above-mentioned drawbacks of polypropylene and to develop a propylene-based polymer composition that retains sufficient flexibility even when placed under a low temperature of about 20 ° C. or less below zero. .
As a result, we identified the ethylene / (meth) acrylic acid alkyl ester copolymer, especially the ethylene / (meth) acrylic acid alkyl ester copolymer produced by the tubular method, in the polypropylene polymer, especially the soft polypropylene polymer. It was found that the composition blended in a quantitative ratio is not only excellent in flexibility and heat resistance, but also excellent in low temperature characteristics, and the present invention was completed based on this finding.

  Accordingly, an object of the present invention is to provide a propylene-based polymer composition which is excellent in flexibility, heat resistance and low temperature brittleness resistance.

According to the present invention, random copolymers of other α- olefins latent heat in the thermal analysis by differential scanning calorimetry (DSC) is composed mainly of less der pulp propylene 80KJ / Kg (A) 90~ Propylene polymer composition comprising 50 parts by mass and 10-50 parts by mass of ethylene / (meth) acrylic acid alkyl ester copolymer (B) (provided that the total amount of (A) and (B) is 100 parts by mass) Things are provided.

Propylene-based polymer composition of the present invention, random copolymers of other α- olefins latent heat in the thermal analysis by differential scanning calorimetry (DSC) is composed mainly of less der pulp propylene 80 kJ / Kg It has structural characteristics in that it is a resin composition rich in propylene polymerization components, which is made by blending a specific amount ratio of ethylene / (meth) acrylic acid alkyl ester copolymer with flexibility, heat resistance and low temperature brittleness. It has a performance characteristic that it is excellent in various properties such as resistance to crystallization.

  In the present invention, the content of the (meth) acrylic acid alkyl ester component in the ethylene / (meth) acrylic acid alkyl ester copolymer is preferably 10 to 39% by mass. The polymer is preferably a copolymer obtained by high-pressure radical polymerization by a tubular method.

The propylene-based resin composition of the present invention has, for example, a flexural modulus (JIS K7125) of 400 MPa or less, a thermal deformation temperature (JIS K7212: one-point fixing method No. 3 dumbbell 100h) of 120 ° C. or more, and the specific configuration described above. The embrittlement temperature is minus 20 ° C. or less, and the flexibility, heat resistance, and low temperature embrittlement resistance are all excellent.
For this reason, in addition to the use as a typical general-purpose plastic, for example, it is suitable as a molding material such as a packaging film for frozen storage of food and the like, a container material, and an industrial part requiring cold resistance.

Hereinafter, preferred embodiments of the present invention will be described in detail and specifically.
The resin composition of the present invention is obtained by blending a propylene-based polymer (A) with an ethylene / (meth) acrylic acid alkyl ester copolymer (B) in a specific amount ratio.

In the composition of the present invention, the propylene-based polymer (A), which is the main blended polymer component, has a latent heat amount of 80 KJ / Kg or less, more preferably 30 to 79 KJ in thermal analysis using a differential scanning calorimeter (DSC). It is a random copolymer containing a small amount of other α-olefin units mainly composed of / Kg of propylene, for example, about 0.01 to 10 mol% or less.

The compositions of the above applications, among front Kipu propylene-based polymer (A), the melting peak temperature (DSC Measurement mp T: JIS K7121 compliant) is 140 ° C. or higher, a flexural modulus (JIS K7171: 94 compliant) is 500MPa or less der Ru copolymer are particularly preferred.

In the propylene polymer (A) , other α-olefins copolymerized with propylene include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1 -The alpha olefin with about 2-20 carbon atoms, such as pentene, can be illustrated.
Such other α-olefins may be copolymerized singly or in combination of two or more.

Particularly preferred random copolymer, a propylene content of 90 to 99.99 mol%, random preferably consisting of propylene and a copolymer or propylene with ethylene and 1-butene in ethylene is from 93 to 99.9 mol% It is a copolymer.

In consideration of miscibility with other components, extrudability, and toughness of the resulting molded product, these propylene polymers (A) are melt flow rate (MFR) (JIS K7210: 99, 230 ° C., 2160 g load). ) Is 0.1 to 100 g / 10 min, more preferably 1 to 70 g / 10 min. The density of these propylene polymers (A) is preferably 870 to 910 kg / m ³ .
These propylene polymers can be used in combination of two or more.

  The ethylene / (meth) acrylic acid alkyl ester copolymer (B), which is another resin component constituting the composition of the present invention, is a copolymer of ethylene and alkyl acrylate or alkyl methacrylate. It may consist of only ethylene and alkyl acrylate or alkyl methacrylate, and other monomers such as carbon monoxide, vinyl esters, acrylic acid, methacrylic acid, maleic acid, maleic A small amount of monomethyl acid or the like may be copolymerized.

  Specific examples of the alkyl acrylate or methacrylic acid alkyl ester monomer constituting the copolymer (B) include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-propyl acrylate, and isobutyl acrylate. , N-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-propyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, s-butyl methacrylate, methacrylic acid Examples thereof include 2-ethylhexyl, and alkyl esters having about 1 to 10 carbon atoms, particularly about 2 to 8 carbon atoms are preferred.

The polymerization composition of the ethylene / (meth) acrylic acid alkyl ester copolymer (B), that is, the content of the (meth) acrylic acid alkyl ester unit in the copolymer (B) is 10 to 39% by mass, more preferably The thing of 15-30 mass% is preferable.
The copolymer (B) has a melt flow rate (MFR) (JIS K7210: 99, 190 ° C., 2160 g load) of 0.1 to 100 g / 10 min, more preferably 0.2 to 30 g / 10 min. Are preferred.

  When the melt flow rate (MFR) is outside the above range, the resin composition obtained by blending it has inferior heat resistance and tensile physical properties, and the obtained molded article has poor workability.

In the ethylene / (meth) acrylic acid alkyl ester copolymer (B) used in the present invention, the melting point of the copolymer by differential scanning calorimetry (DSC) is particularly preferred as the copolymer. It can be mentioned that the relationship between T (based on JIS K7121) and its (meth) acrylic acid ester unit content (X: mol%) has a relationship represented by the following formula (1).
−3.0X + 125 ≧ T ≧ −3.0X + 109 (1)

  A copolymer having a melting point and ester unit content as described above has a smaller random arrangement of ethylene units and (meth) acrylic acid ester units than a normal copolymer having good randomness, The alignment heterogeneity is high, and the polymer structure and physical properties are somewhat similar to those of block copolymers.

  Such a copolymer can be produced, for example, by performing multistage polymerization in an autoclave or polymerizing in a tubular reactor (tubular reactor) in a high-pressure radical polymerization method (for example, patents). No. 3423308, JP-A-62-273214, etc.). In the present invention, it is particularly preferable to use an ethylene / (meth) acrylic acid alkyl ester copolymer (B) produced by high-pressure polymerization in a tubular reactor (tubular reactor).

  The resin composition of the present invention comprises 90 to 50 parts by mass of the propylene polymer (A), preferably 85 to 55 parts by mass, and 10 to 50 parts by mass of the ethylene / (meth) acrylic acid alkyl ester copolymer (B). Part, preferably 15 to 45 parts by mass (provided that the total amount of (A) and (B) is 100 parts by mass).

The composition of the present invention contains, for example, various peroxides, divinylbenzene, diallyl phthalate, glycoxal, glycidyl (meth) acrylate, allyl glycidyl ether, diisocyanate and the like depending on applications and required specifications. Or modification modification such as partial cross-linking can be performed by irradiation with light, ultraviolet rays or radiation.
Further, as in the case of ordinary resin compositions, any additive, for example, an ultraviolet absorber, an antioxidant, a weather resistance stabilizer, an antistatic agent, a slip agent, a pigment, and a dye, may be appropriately selected depending on the application and purpose. Further, a tackifier, an inorganic filler, a foaming agent, a sliding agent, an anti-blocking agent, a flame retardant (organic or inorganic), a surfactant, an inorganic filler, and the like may be added and blended.

The composition of the present invention can be prepared by mixing and melt-kneading using an extruder, a kneader or the like.
The composition obtained by the melt-kneading or the like may be immediately processed into a molded product, or may be molded after being once pelletized.

Examples and comparative examples are shown below to explain the effects of the present invention.
In addition, the physical property evaluation method of the raw material used in the Example etc. and the obtained composition material sample is as follows.

1. Raw material resin (1) Propylene polymer (A)
Sample A-1 Propylene homopolymer (E2900 manufactured by Prime Polymer Co., Ltd.): MFR 2.8 g / 10 min (230 ° C., 2160 g load), melting point 160 ° C., latent heat of fusion 77.8 KJ / Kg
Sample A-2 Propylene / ethylene random copolymer (Prime Polymer (E2740): MFR 2.8 g / 10 min (230 ° C., 2160 g load), melting point 145 ° C., latent heat of fusion 52.1 KJ / Kg
(2) Ethylene / (meth) acrylic acid alkyl ester copolymer Sample B-1 Ethylene / methyl acrylate copolymer: Methyl acrylate content 25% by mass, MFR (according to JIS K7210, 190 ° C., 2160 g load) 0 .4g / 10min Melting point (JIS K7112) 90 ° C

2. Evaluation items and measurement method 1) Melt flow rate (MFR) Propylene polymer: JIS
K7210: 99 (230 ° C., 2160 g load), ethylene / (meth) acrylic acid alkyl ester copolymer: JIS K7210: 99 (190 ° C., 2160 g load)
2) Melting point (mp) and latent heat of fusion (ΔH): Measured with a differential scanning calorimeter (DSC: DSC2910 manufactured by TA instrument).
3) Brittle temperature (° C); according to JIS K 6261 4) Flexural rigidity: according to JIS K 7125 (Olsen type)

"Example 1" (reference example)
A test piece sample having a predetermined shape was prepared by melting and kneading 80 parts by mass of polymer A-1 (propylene homopolymer) and 20 parts by mass of polymer B-1 (ethylene / methyl acrylate copolymer). The bending rigidity and the embrittlement temperature were evaluated.
The results are shown in Table 1.
Example 2 (Invention)
A composition was prepared in the same manner as in Example 1 except that polymer A-2 (propylene / ethylene random copolymer) was used instead of polymer A-1 in Example 1. Example 1 The bending rigidity and the embrittlement temperature were evaluated in the same manner.
The results are shown in Table 1.

“Comparative Example 1 and Comparative Example 2”
The polymer A-1 was molded into a test piece sample as it was and evaluated in the same manner as in Example 1 (Comparative Example 1). Further, the polymer A-2 was molded into a test piece sample as it was and the same as in Example 1. Evaluation (Comparative Example 2).
The results are summarized in Table 1.

Claims (4)

Random copolymers of other α- olefins latent heat in the thermal analysis by differential scanning calorimetry (DSC) is mainly composed of propylene emissions or less 80KJ / Kg (A) 90~50 parts by weight of ethylene · ( A propylene-based polymer composition comprising 10 to 50 parts by mass of a (meth) acrylic acid alkyl ester copolymer (B) (provided that the total amount of (A) and (B) is 100 parts by mass). Furthermore, UV absorbers, antioxidants, weather resistance stabilizers, antistatic agents, slip agents, pigments, dyes, tackifiers, inorganic fillers, foaming agents, sliding agents, antiblocking agents, organic flame retardants, The propylene polymer composition according to claim 1, comprising an arbitrary additive selected from an inorganic flame retardant, a surfactant, and an inorganic filler. The composition according to any one of claims 1 and 2 , wherein a content of the (meth) acrylic acid alkyl ester component in the ethylene / (meth) acrylic acid alkyl ester copolymer (B) is 10 to 39% by mass. object. The composition according to any one of claims 1 to 3 , wherein the ethylene / (meth) acrylic acid alkyl ester copolymer (B) is a copolymer obtained by a tubular method.