JPH0873671A - Thermoplastic resin composition - Google Patents

Abstract

PURPOSE: To obtain a composition containing a specific amount of sorbitol-based nucleating agent, etc., and capable of making it highly transparent without taking complex factors of various parameters which exercise an influence on transparency and these correlations, etc., into consideration. CONSTITUTION: This composition contains preferably 0.1-0.5wt.% (especially 0.1-0.3wt.%) of a sorbitol-based nucleating agent of the formula (R1 and R2 are each H, C1 or 1-4C alkyl) and has 0.1-100g/10min (preferably 1-80g/10min) melt flow (MFR, at 230 deg.C under 2.16kg load) and >=0.5 (preferably 0.6-2.0) ratio (s2 /s1 ) of inclination (s2 ) at 10<-1> to 10<-3> -rad/sec to inclination (s1 ) at 10<3> to 10<1> rad/ sec. Furthermore, 1,-3, 2, 4-dibenzilidenesorbitol, 1,3-P-chlorbenzylidene-2, 4-P- methyl-benzylidenesorbitol, etc., is exemplified as a preferable example of the nucleating agent.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a highly transparent polypropylene resin composition.

[0002]

2. Description of the Related Art In order to improve the transparency of conventional polypropylene resin compositions,
JP-A-54-88950, JP-A-56-30499, JP-A-58-
As described in Japanese Patent No. 25341, a method for producing a random copolymer portion by incorporating ethylene into a polypropylene resin composition, a metal salt of a carboxylic acid, a metal salt of an aromatic carboxylic acid, a metal salt of an aromatic phosphoric acid. , A method of blending additives such as sorbitol-based compounds is used.

Although these methods may be used alone, they may be used in combination when mechanical strength such as toughness and rigidity is important. Therefore, in order to obtain a certain level of transparency or more, it is necessary to consider the resin design of the random copolymer part and the type and amount of the additive.

Further, when the polypropylene polymer is produced by different catalyst systems and processes, not only are the components and amounts of the catalyst residue different, but is ethylene dispersed in the propylene chain or blocky? , The degree of randomness of ethylene will be different.
Since these factors affect the transparency of the resin, when different polypropylene polymers are used, these factors also need to be considered in order to improve the transparency.
In addition, other inorganic fillers, antistatic agents, additives such as lubricants affect the transparency.

Therefore, in order to obtain a polypropylene resin composition having a certain level or more of transparency, various factors or their correlations must be taken into consideration depending on the situation.

Therefore, an object of the present invention is to improve the transparency of a polypropylene resin composition without taking into consideration various factors affecting the transparency of the polypropylene resin composition and their complicated factors such as their correlation. It is to provide things.

[0007]

Means for Solving the Problems As a result of intensive studies in view of the above object, the present inventors have found that various factors affecting the transparency of a polypropylene resin composition summarize the specific physical properties of the polypropylene resin composition. It was found that the transparency can be controlled by keeping the physical property at a certain constant value, and the present invention was conceived.

That is, the polypropylene resin composition of the present invention has a melt flow rate (MFR, 230 ° C., 2.16 kg load) of 0.1 to 100 g / 10 min, and a melting point of 10 ³ to 10 ° C. Slope of melt viscosity in the frequency range of 10 ¹ rad / sec s Slope from 10 ^-1 to 10 ^-3 rad / sec s ₁
The ratio s ₂ / s ₁ of ₂ being greater than 0.5.

The present invention is described in detail below. [1] Physical Properties of Polypropylene Resin Composition (a) Melt Flow Rate (MFR, 230 ° C., 2.16 kg Load) The polypropylene resin composition of the present invention has an MFR of 0.1 to 10
It is 0 g / 10 minutes, preferably 1 to 80 g / 10 minutes.
If the MFR is less than 0.1 g / 10 minutes, the fluidity during molding is lowered and the moldability is poor, and if the MFR exceeds 100 g / 10 minutes, the mechanical strength such as impact strength and toughness is deteriorated, which is not preferable.

[0010] (b) s ₂ / s ₁ ratio in the present invention, in the temperature range of melting point ± 10 ℃ polypropylene resin composition, 10 ³ to 10 ¹ rad / sec and 10 ^-1 to 10 ^-3
When the melt viscosity is considered to have a linear relationship with the frequency in the frequency range of rad / sec and the respective slopes s ₁ and s ₂ are obtained by the least squares method, the ratio s ₂ / s ₁ should be greater than 0.5. To improve transparency.
If the s ₂ / s ₁ ratio is 0.5 or less, good transparency cannot be obtained. More preferred s ₂ / s ₁ ratio is 0.6 to 2.0.

S ₂ of the polypropylene resin composition of the present invention
The factor that changes the / s ₁ ratio is that the resin composition
MFR, ethylene content in the resin composition, ratio of propylene-ethylene random copolymer portion in the resin composition, ethylene content of the propylene-ethylene random copolymer portion, transparency improving additive used Type and amount, type and amount of catalyst residue component, presence or absence of crosslinked product formation,
Inorganic filler, organic filler, antioxidant, light stabilizer, lubricant, antistatic agent, antifogging agent, antiblocking agent, pigment, heavy metal deactivator, radical generator, dispersant, neutralizer And the type and amount of additives.

Among the factors that change the s ₂ / s ₁ ratio, the type and amount of the transparency improving additive, the type and amount of the catalyst residue component, and the type and amount of the neutralizing agent are the s ₂ / s ₁ ratio. Have a significant impact on. Therefore, the selection of the optimum transparency improving additive and the addition of the effective amount, the elimination of the catalyst residue component by the decatalysis process and the selection of the optimum neutralizing agent and the addition of the effective amount are important adjustment methods.

[2] Composition (a) Propylene-based resin In the propylene resin composition of the present invention, a propylene homopolymer or a propylene-ethylene copolymer containing a small amount of ethylene can be used. Propylene-ethylene copolymer is a block copolymer, a random copolymer,
Any of alternating copolymers may be used, but propylene-ethylene random copolymer is particularly preferable.

The propylene homopolymer has an MFR of 0.
1 to 100 g / 10 min, preferably 1 to 80 g / 10 min is used. If the MFR is less than 0.1 g / 10 min, the moldability will be low, and if it exceeds 100 g / 10 min, the mechanical strength such as impact resistance and toughness will decrease. The method for producing the propylene homopolymer is not particularly limited, but a polymerization method using a stereoregular catalyst is preferable. Examples thereof include titanium trichloride, titanium tetrachloride, titanium halide compounds such as trichloroethoxytitanium, transition metal components such as a contact product of the titanium halide compound and a magnesium compound represented by magnesium halide, and alkyl. Two-component catalysts with aluminum compounds or their halogen compounds, hydrides, alkoxides and other organometallic components, and electron donating compounds containing nitrogen, phosphoric acid, sulfur, oxygen, silicon, etc. added to these components 3 There are component-based catalysts.

The polymerization reaction of the propylene homopolymer may be carried out in either the gas phase or the liquid phase. For example, when polymerizing in a liquid phase, n-butane, isobutane, n-pentane, isopentane, hexane, heptane, octane,
It can be carried out in an inert hydrocarbon or liquid monomer such as cyclohexane, benzene, toluene, xylene.
The polymerization temperature is usually −80 to 150 ° C., preferably 40 to
It is 120 ℃. The polymerization pressure is preferably 1 to 60 atm, and the molecular weight of the resulting polymer can be controlled by hydrogen or other known molecular weight regulators. Polymerization is carried out by a continuous or batch reaction, and the conditions may be those usually used. Further, the polymerization reaction may be carried out in one step,
You may go in two steps.

The method for producing the propylene-ethylene copolymer is not particularly limited, and a propylene homopolymer is produced in the preceding stage in the above-mentioned propylene polymerization, and then ethylene is added to produce a propylene-ethylene copolymer. Method, or an ethylene homopolymer or a propylene-ethylene copolymer is produced in advance by the same production method as that for the propylene homopolymer, and this is machined with the propylene homopolymer in a post reactor blend or a super mixer. And the like.

(B) Transparency improver In order to obtain a high s ₂ / s ₁ ratio, the following general formula (1):

Embedded image (In the formula, R ₁ and R ₂ represent H, Cl or an alkyl group having 1 to 4 carbon atoms.) It is preferable to add a sorbitol-based nucleating agent.

Examples of the sorbitol compound as described above include 1,3,2,4-dibenzylidene sorbitol, 1,3-benzylidene-2,4-p-methylbenzylidene sorbitol and 1,3-
Benzylidene-2,4-p-ethylbenzylidene sorbitol, 1,3-p-methylbenzylidene-2,4-benzylidene sorbitol, 1,3-p-ethylbenzylidene-2,4-benzylidene sorbitol, 1,3-p- Methylbenzylidene-2,4-p-ethylbenzylidene sorbitol, 1,3-p-Ethylbenzylidene-2,4-p-methylbenzylidene sorbitol, 1,3,2,
4-di (p-methylbenzylidene) sorbitol, 1,3,2,4-
Di (p-ethylbenzylidene) sorbitol, 1,3,2,4-di (pn-propylbenzylidene) sorbitol, 1,3,2,4-
Di (pi-propylbenzylidene) sorbitol, 1,3,2,
4-di (pn-butylbenzylidene) sorbitol, 1,3,2,
4-di (ps-butylbenzylidene) sorbitol, 1,3,2,
4-di (pt-butylbenzylidene) sorbitol, 1,3,2,
4-di (p-methoxybenzylidene) sorbitol, 1,3,2,
4-di (p-ethoxybenzylidene) sorbitol, 1,3-benzylidene-2,4-p-chlorobenzylidene sorbitol,
1,3-p-Chlorobenzylidene-2,4-benzylidene sorbitol, 1,3-p-Chlorobenzylidene-2,4-p-methylbenzylidene sorbitol, 1,3-p-Chlorobenzylidene-2,4-p
-Ethylbenzylidene sorbitol, 1,3-p-Methylbenzylidene-2,4-p- chlorobenzylidene sorbitol, 1,
3-p-Ethylbenzylidene-2,4-p-chlorobenzylidene sorbitol and 1,3,2,4-di (p-chlorobenzylidene)
Examples include sorbitol and the like. Among these, 1,3,2,4-
Dibenzylidene sorbitol, 1,3,2,4-di (p-methylbenzylidene) sorbitol, 1,3-p-chlorobenzylidene
-2,4-p-methylbenzylidene sorbitol is preferred.

The amount of these sorbitol-based nucleating agents added is preferably 0.1 to 0.5% by weight, more preferably 0.1 to 0.3% by weight, based on 100% by weight of the composition. If the added amount is less than 0.1% by weight, the effect of the addition cannot be obtained, and
If it exceeds 5% by weight, problems such as contamination of the mold during molding, occurrence of bleed-out, increase of odor and the like are not preferable.

To add the sorbitol nucleating agent, the propylene homopolymer or propylene-ethylene copolymer and a predetermined amount of the sorbitol nucleating agent are mixed by stirring with a ribbon blender, a tumbler mixer, a Henschel mixer, a super mixer or the like. , And then mix the mixture using a roll, Banbury mixer, extruder, etc.
It is preferably melt-kneaded at 180 to 250 ° C.

(C) Other Additives The polypropylene resin composition of the present invention contains silica, alumina, talc, mica, clay, kaolin, wollastonite, zeolite, silica-alumina, calcium carbonate, depending on the application. Aluminum hydroxide, silicon dioxide, titanium dioxide, zinc oxide, magnesium oxide, zirconium oxide, zinc sulfide, barium sulfate, calcium sulfate, calcium phosphate, magnesium phosphate, aluminum silicate, silicon nitride, glass, hydrotalcite, glass fiber, Granular, powdery, scaly or fibrous inorganic filler such as potassium titanate fiber, carbon fiber, carbon black, graphite, mica ceramics fiber, metal fiber, or organic such as wood flour, pulp, synthetic fiber or natural fiber Fillers can be included. The inorganic filler may be surface-treated with a silane-based, titanate-based, boron-based, aluminate-based, zirconia-based, or zirconia-aluminate-based coupling agent.

Further, in addition, phenol-based, thioether-based, phosphorus-based antioxidants, light stabilizers, clarifiers,
Nucleating agents such as organic carboxylic acids or metal salts thereof, lubricants, antistatic agents, antifogging agents, antiblocking agents, pigments, heavy metal deactivators, radical generators such as peroxides, metal soaps, etc. A dispersant, a neutralizing agent or the like may be added within a range that does not impair the object of the present invention.

[0023]

EXAMPLES The present invention will now be described in more detail with reference to specific examples, but the present invention is not limited thereto.

Example 1 100 parts by weight of a propylene-ethylene random copolymer (manufactured by Tonen Kagaku Co., Ltd.) having an ethylene content of 2.9% by weight was added to a radiation-resistant additive hindered amine compound (manufactured by Ciba Geigy, trade name T). -62LLO) 0.1 part by weight and triallyl isocyanurate (manufactured by Nippon Kasei Co., Ltd., trade name TAIC) 0.5 part by weight were mixed, and a cobalt 60 radiation source was used to irradiate γ-rays with a dose of 2.5 megarads. , Cross-linked. This resin composition was extruded into pellets at a die exit temperature of 230 ° C using a single-screw extruder with a diameter of 50 mm, then using an injection molding machine, a resin temperature of 240 ° C, an injection pressure of 400 kg / cm ² and A test piece having a thickness of 1 mm was prepared under the condition that the mold temperature was 30 ° C.

The MFR (23
(0 ° C., 2.16 kg load) and the s ₂ / s ₁ ratio were measured, and the haze value was measured using the obtained test piece. Table 1 shows the measurement results. MFR measurement is JIS K721
The haze value was measured in accordance with ASTM D-1003 using a test piece having a thickness of 1 mm.

In addition, s₂/ S₁The ratio is calculated as follows.
I have First, relax the sample at 200 ° C for 10 minutes, and then measure it.
Cool to 150-160 ℃, and after the temperature stabilizes,
Frequency dependence of melt viscosity is measured (dynamic melt viscoelasticity measurement)
did. Then the frequency 10³~Ten ¹ rad / sec and 10^-1~Ten^-3
 Melt viscosity has a linear relationship with frequency at rad / sec
Each frequency range by the method of least squares
The slope s of the straight line at₁And s₂Seeking those ratios
 s₂/ S₁Was calculated. Table 1 shows the results.

Examples 2 to 6 The propylene-ethylene random copolymer (manufactured by Tonen Kagaku Co., Ltd.) having an ethylene content of 2.9% by weight and the resin composition obtained as a whole are shown in Table 1 as 100% by weight. Ratio of 1,
After mixing 3,2,4-di (p-methylbenzylidene) sorbitol (manufactured by Shin Nippon Rika Co., Ltd .; trade name Gelol MD) using a Henschel mixer, using a single screw extruder with a diameter of 50 mm, It was extruded at a die outlet temperature of 230 ° C. to obtain a pelletized propylene resin composition. Next, from the obtained pellet-shaped polypropylene resin composition, a resin temperature of 240
° C., an injection pressure of 400 kg / cm ² and mold temperature 30 ° C., to produce a test piece having a thickness of 1 mm. MFR (230 ° C., 2.16 kg load), s ₂ / s ₁ ratio and haze value were measured in the same manner as in Example 1. Table 1 shows the measurement results.

Comparative Example 1 Using the same propylene-ethylene random copolymer as in Example 1, a test piece was prepared in the same manner as in Example 1. Next, as in Example 1, MFR (230 ° C, 2.16 kg load)
, S ₂ / s ₁ ratio, and haze value were measured. Table 1 shows the measurement results.

Comparative Example 2 The same as Example 1 except that the addition amount of 1,3,2,4-di (p-methylbenzylidene) sorbitol was 0.06% by weight and the s ₂ / s ₁ ratio was 0.5 or less. Then, a polypropylene resin composition and a test piece using the same were prepared, and MFR (230 ° C., 2.16 kg load), s ₂ / s ₁ ratio, and haze value were measured in the same manner as in Example 1. . Table 1 shows the measurement results.

Table 1 Physical Properties Nucleating Agent Compounding Amount MFR Haze Value Example NO. (Wt%) (g / 10 minutes) s ₂ / s ₁ ratio (%) Example 1 0 9 0.7 12 Example 2 0.15 15 1.201 10 Example 3 0.2 15 1.37 9 Example 4 0.2 1 1.09 12 Example 5 0.2 30 0.68 10 Example 6 0.2 100 0.75 11 Comparative Example 1 0 15 0.23 20 Example 2 0.06 15 0.213 20

As is apparent from Table 1, the polypropylene resin composition of the present invention has a s ₂ / s ₁ ratio of more than 0.5, and therefore has a small haze value and good transparency.

[0032]

As described above in detail, according to the method of the present invention, transparency is improved by controlling specific physical characteristics when various complicated factors affecting transparency are taken into consideration. Therefore, a highly transparent polypropylene resin composition can be easily produced. Since the polypropylene resin composition of the present invention has high transparency, a food container,
Suitable for medical instruments, physics and chemistry laboratory instruments, etc.

Claims (2)

[Claims] 1. Melt flow rate (MFR, 230 ° C., 2.16)
(kg load) is 0.1 to 100 g / 10 minutes, and the melting point is ± 10 ° C.
, The ratio of the slope s ₂ at 10 ^-1 to 10 ^-3 rad / sec to the slope s ₁ of the melt viscosity in the frequency range 10 ³ to 10 ¹ rad / sec s ₂ / s ₁ is greater than 0.5. A polypropylene resin composition comprising: 2. The polypropylene resin composition according to claim 1, wherein the polypropylene resin composition has the following general formula (I): (In the formula, R ₁ and R ₂ represent H, Cl or an alkyl group having 1 to 4 carbon atoms.) A sorbitol-based nucleating agent represented by
A polypropylene resin composition comprising 0.1 to 0.5% by weight.