JP4430375B2 - Polypropylene resin foam molding - Google Patents

Description

  The present invention relates to a polypropylene resin foam molded article used for a heat insulating material, a shock-absorbing wrapping material, a box, a bumper core material for automobiles, a vehicle member, and the like.

Polypropylene-based resin foam moldings are superior to polystyrene-based resin foam moldings in terms of chemical resistance, heat resistance, and strain recovery after compression. It is widely used for automobile parts such as pillars, platforms, and side impact materials, and molded products for conveyance such as pallet materials and tool boxes. In addition, the polypropylene resin foam molded article is superior in heat resistance and compressive strength as compared with the polyethylene resin foam molded article.
Therefore, polypropylene-based resin foam molded products are used for members that require use at high temperatures and strength.

  Among the various uses described above, in particular, as a heat insulating material or a structural member, in addition to high heat resistance and compressive strength, low water vapor permeability is required.

  In the case of conventional polypropylene resin foamed molded products, if the secondary foaming property of the foamed particles during bead molding (in-mold molding using foamed particles) is given priority, propylene having a high moisture permeability as the base resin for the foamed particles. The use of a polymer is forced. Conversely, if a propylene-based polymer having a low moisture permeability is used as the base resin for the foam particles, the secondary foamability of the foam particles during bead molding will be reduced, and the resulting foam molded product will have minute amounts between the foam particles. Many voids will be present. In any case, the moisture permeability of the conventional polypropylene resin foamed molded product has to be increased.

  In order to reduce the moisture permeability of the polypropylene resin foam molded body, for example, a technique for welding a moisture-proof film to the surface of the molded body (see Patent Document 1) has been proposed.

  However, in the technique using the moisture-proof film, there is a problem that the cost is increased because a process for welding the film is newly required. Furthermore, due to the presence of the film itself, the scratch resistance of the final molded body is lowered, and as a result, the appearance of the molded body is impaired. Therefore, there has been a demand for a material that exhibits low water vapor permeability with a foamed molded product alone.

JP 63-212543 A (Claims)

  The present invention has been made in view of such conventional problems, and intends to provide a propylene-based resin foam molded article having excellent heat resistance and strength, low water vapor permeability and moisture permeability, and excellent moisture resistance. Is.

The present invention is a polypropylene resin foam molded article obtained by thermoforming foamed particles obtained using a metallocene polymerization catalyst and having a propylene polymer having the following requirements (a) and (b) as a base resin: Because
The polypropylene resin foam molded article is a polypropylene resin foam molded article having the following requirement (c) (Claim 1).
(A) The structural unit obtained from propylene is 100 to 85 mol%, and the structural unit obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms is present in an amount of 0 to 15 mol% (provided from propylene) The total amount of structural units and structural units obtained from ethylene and / or α-olefin having 4 to 20 carbon atoms is 100 mol%).
(B) The proportion of position irregular units based on 2,1-insertion of propylene monomer units in all propylene insertions measured by ¹³ C- NMR is 0.5 to 2.0%, and propylene monomer units The proportion of irregular units based on 1,3-insertion is 0.08 to 0.4%.
(C) The density X of the polypropylene resin foam molded article is 0.008 to 0.052 g / cm ³ , and the moisture permeability Y [g / m ² / hr] measured in accordance with ASTM E-96; The density X [g / cm ³ ] of the polypropylene resin foamed molded article satisfies the following formula (2).
Y ≦ (43.6) × X ² − (4.5) × X + 0.15 Formula (2)

The polypropylene resin foam molded article of the present invention is molded using foamed particles whose base resin is a propylene polymer having the above requirements (a) and (b), and is shown in the above requirement (c). Thus, the moisture permeability Y and the density X satisfy the above formula (2).
Therefore, the polypropylene resin foam molded article exhibits very low moisture permeability and water vapor permeability while maintaining excellent heat resistance and strength unique to the propylene resin.
Therefore, the polypropylene resin foam molded article is suitable for applications such as a heat insulating material, a structural member for construction, and a packaging material.

  Moreover, the polypropylene resin foam molded article of the present invention has an excellent characteristic that water vapor permeability and moisture permeability are low (moisture permeability is small). Therefore, it becomes possible to make the thickness and density of the said polypropylene resin foaming molded object required in order to achieve fixed moisture resistance to be smaller than the conventional one.

The reason why the moisture permeability of the polypropylene resin foam molded article of the present invention is lower than that of a conventional foam molded article using a polypropylene resin is estimated as follows.
That is, the propylene polymer having the above requirements (a) and (b), which is the base resin of the polypropylene resin foam molded article of the present invention, has a low moisture permeability and excellent foamability. Therefore, the foam molded product obtained from the expanded particles using such a propylene-based polymer as the base resin is a fine material that can be generated between the expanded particles that reduce the moisture resistance in addition to the excellent low moisture permeability of the base resin. Effective voids can be effectively reduced. As a result, it is presumed that the moisture permeability resistance becomes higher than the conventional polypropylene resin foam molded article, and the moisture permeability decreases.

  Moreover, the polypropylene resin foam molded article of the present invention can be produced, for example, by a normal bead molding method. Therefore, the polypropylene resin foamed molded article can be obtained easily and at low cost without requiring special equipment.

Furthermore, the polypropylene resin foam molded article of the present invention is formed by molding expanded particles having a specific propylene polymer as a base resin as described above.
For this reason, when the expanded particles are molded by, for example, a bead molding (in-mold molding) method, the required water vapor pressure can be lowered. In addition, the time required for cooling during molding can be shortened. That is, the amount of energy required for molding the polypropylene resin foam molded article can be reduced.

  Thus, according to the present invention, it is possible to provide a propylene-based resin foam molded article having excellent heat resistance and strength, low water vapor permeability and moisture permeability, and excellent moisture resistance.

In the present invention, the expanded particles contain a propylene polymer having the requirements (a) and (b) as a base resin.
Here, the base resin means a basic resin component constituting the foamed particles. The expanded particles may contain the base resin and other polymer components added as necessary, or additives such as a foaming agent, a catalyst neutralizing agent, a lubricant, a crystal nucleating agent, and other additives. Good. However, it is desirable that other polymer components and additives be as small as possible within the range not impairing the object of the present invention.
That is, when the propylene polymer is 100 parts by weight, the amount of other polymer components added is preferably 40 parts by weight or less. More preferably, it is 30 parts by weight or less, and more preferably 15 parts by weight or less. Most preferably, it is 5 parts by weight or less.
When the propylene-based polymer is 100 parts by weight, the amount of the additive (except for the foaming agent that does not eventually disperse) depends on the purpose of use of the additive. Part by weight or less is preferred. More preferably, it is 30 parts by weight or less, and more preferably 0.001 to 15 parts by weight.

Below, the said requirement (a) is demonstrated first.
The requirement (a) is that the structural unit obtained from propylene is 100 to 85 mol%, and the structural unit obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms is present in 0 to 15 mol%.
Here, the total amount of the structural unit obtained from propylene and the structural unit obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms is 100 mol%.
Therefore, the propylene polymer satisfying the requirement (a) includes a propylene homopolymer or a copolymer of propylene and ethylene and / or an α-olefin having 4 to 20 carbon atoms.

  Specific examples of the ethylene comonomer copolymerized with propylene and / or the α-olefin having 4 to 20 carbon atoms include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4- And methyl-1-pentene.

  In the present invention, as a propylene polymer satisfying the above requirement (a), a copolymer obtained by copolymerizing propylene with another monomer that has been difficult to polymerize with a conventional Ziegler / Natta catalyst can be used. In this case, the structural unit obtained from the other monomer is preferably 0.01 to 20 mol%, more preferably 0.05 to 10 mol% in the propylene polymer.

  Examples of such other monomers include cyclic olefins such as cyclopentene, norbornene, 1,4,5,8-dimethano-1,2,3,4,4a, 8,8a, 5-octahydronaphthalene, 5- Chain non-conjugated dienes such as methyl-1,4-hexadiene, 7-methyl-1,6-octadiene, 4-ethylidene-8-methyl-1,7-nonadiene, 5-ethylidene-2-norbornene, dicyclopentadiene , 5-vinyl-2-norbornene, or a cyclic non-conjugated polyene such as norbornadiene, or an aromatic unsaturated compound such as styrene or divinylbenzene, can be used.

  The propylene-based polymer used in the present invention is a propylene-based (co) polymer resin containing 85 mol% to 100 mol% of a structural unit obtained from propylene in the propylene-based polymer as in the above requirement (a). It is necessary that the structural unit obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms is contained in a proportion of 0 to 15 mol%.

  When the structural unit of the comonomer is out of the above range (exceeding 15 mol%), mechanical properties such as bending strength and tensile strength of the propylene polymer are greatly deteriorated. And even if it produces foamed particles using such a propylene-type polymer for base resin, the polypropylene-type resin foam molding excellent in intensity | strength cannot be obtained.

  In the propylene polymer, the structural unit obtained from propylene is 99.5 to 85.0 mol%, and the structural unit obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms is 0.5 to 5%. 15.0 mol% is preferably present (however, the total amount of structural units obtained from propylene and structural units obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms is 100 mol%) .

  In this case, a structural unit obtained from the propylene and a structural unit obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms are essential components. And the said foaming particle formed by containing such a propylene-type polymer as said base resin is excellent in the secondary foaming property at the time of bead shaping | molding.

In the propylene-based polymer, the structural unit obtained from propylene can be 100 mol%, that is, the structural unit obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms can be 0 mol%.
In this case, the propylene polymer is a so-called propylene homopolymer. And the said polypropylene resin foaming molding obtained by using such a propylene polymer becomes the thing which was further excellent in the intensity | strength.

Next, as shown in the requirement (b), the propylene-based polymer has a proportion of position irregular units based on 2,1-insertion of propylene monomer units in all propylene insertions measured by ¹³ C- NMR. It is 0.5 to 2.0%, and the proportion of position irregular units based on 1,3-insertion of propylene monomer units is 0.08 to 0.4%.
This requirement (b) relates to the proportion of position irregular units of the propylene polymer, and such irregular units have the effect of lowering the crystallinity of the propylene polymer and show the effect of improving foamability. .

  Further, the polypropylene resin foam molded article obtained by using the propylene polymer in which the proportion of the irregular units is in the range of the requirement (b) is characterized in that its compression set becomes small.

  When the ratio of irregular position units based on 2,1-insertion is less than 0.5%, or when the ratio of position irregular units based on 1,3-insertion is less than 0.005%, The effect of making the bubble diameter of the expanded particles uniform is reduced. Moreover, the effect which raises foaming property is low. As a result, there is a problem that the water vapor permeability of the polypropylene resin foam molded article obtained by molding the foamed particles is increased. Further, when the ratio of the position irregular unit based on the 2,1-insertion is less than 0.5%, or the ratio of the position irregular unit based on the 1,3-insertion is less than 0.005%. , The compression set of the obtained polypropylene resin foam molding tends to increase.

  On the other hand, when the ratio of the position irregular unit based on the 2,1-insertion exceeds 2.0%, or the ratio of the position irregular unit based on the 1,3-insertion exceeds 0.4%. However, there is a problem that mechanical properties such as bending strength and tensile strength of the propylene-based polymer are lowered, and as a result, mechanical properties of the polypropylene-based resin foam molded product are also deteriorated.

Here, the structural unit obtained from propylene in the propylene-based polymer, the fraction of structural units obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms, and the isotactic triad fraction described later are: It is a value measured using a ¹³ C- NMR method.

The measurement method of ¹³ C- NMR spectrum is, for example, as follows.
That is, a sample of about 350 to 500 mg was placed in an NMR sample tube having a diameter of 10 mmφ and completely dissolved using about 2.0 ml of o-dichlorobenzene as a solvent and about 0.5 ml of deuterated benzene for locking. Thereafter, measurement was performed at 130 ° C. under the condition of complete proton decoupling.

As measurement conditions, a flip angle of 65 deg and a pulse interval of 5T1 or more (where T1 is the longest value of the spin lattice relaxation time of the methyl group) were selected. In the propylene polymer, since the spin lattice relaxation time of the methylene group and methine group is shorter than that of the methyl group, the recovery of the magnetization of all the carbons is 99% or more under these measurement conditions.
The detection sensitivity of the position irregular unit in the ¹³ C- NMR method is usually about 0.01%, but it can be increased by increasing the number of integrations.

  In addition, the chemical shift in the above measurement was set with 21.8 ppm as the peak of the 3rd unit methyl group in the 5 units of propylene units that are head-to-tail bonded and have the same methyl branching direction. The chemical shifts of other carbon peaks were set as

  Using this criterion, the peak based on the methyl group of the second unit in the three propylene units represented by PPP [mm] in the following formula [Chemical Formula 1] is in the range of 21.3 to 22.2 ppm. The peak based on the methyl group of the second unit in the three propylene units represented by [mr] is in the range of 20.5 to 21.3 ppm, and the second unit in the three propylene units represented by PPP [rr] The peak based on the methyl group of the eye appears in the range of 19.7 to 20.5 ppm.

  Here, PPP [mm], PPP [mr], and PPP [rr] are each represented by the following formula [Formula 1].

  Furthermore, in the present invention, the propylene-based polymer includes partial structures (I) and (II) of the following formula [Chemical Formula 2] containing regioregular units based on 2,1-insertion and 1,3-insertion of propylene. Is contained in a specific amount.

Such a partial structure is considered to occur due to positional irregularities that occur during the polymerization of a propylene polymer, for example, when a polymerization reaction is carried out using a metallocene catalyst.
That is, the propylene monomer usually reacts by a method in which the methylene side is bonded to a metal component in the catalyst, that is, so-called “1,2-insertion”, but rarely “2,1-insertion” or “1” , 3-insertion ". “2,1-insertion” is a reaction mode in which the addition direction is opposite to “1,2-insertion”, and is a structure represented by the partial structure (I) of the above formula [Chemical Formula 2] in the polymer chain. Form a unit.

  “1,3-insertion” means that a propylene monomer is incorporated into a polymer chain by C-1 and C-3, and as a result, a linear structural unit, that is, the above formula [Chemical Formula 2]. The partial structure (II) is obtained.

  The propylene-based polymer in which the ratio of each position irregular unit is within the range of the requirement (b) can be obtained by selecting an appropriate catalyst. Specifically, it can be obtained using, for example, a metallocene polymerization catalyst having a hydroazurenyl group as a ligand. Here, the metallocene polymerization catalyst comprises a transition metal compound component having a metallocene structure and a promoter component. The proportion of each position irregular unit varies depending on the chemical structure of the metal complex component of the catalyst used in the polymerization, but generally the higher the polymerization temperature, the higher the tendency. In the present invention, the polymerization temperature is preferably 0 to 80 ° C. in order to make the proportion of each position irregular unit in the propylene-based polymer within the above specific range.

The metal complex component can be used as a catalyst component as it is, but as a solid catalyst in which the metal complex component is supported on an inorganic or organic particulate carrier which is a granular or particulate solid. It may be used.
When the metal complex component is supported on the fine particle carrier, the amount of the metal complex component supported is preferably 0.001 to 10 mmol, more preferably 0.001 to 5 mmol, per 1 g of the carrier.

Among the metallocene catalysts having the hydroazurenyl group as a ligand, a catalyst using titanium, zirconium, or hafnium as a metal atom is preferable, and a complex having zirconium is preferable because of its high polymerization activity. .
Among the metallocene catalysts, zirconium dichloride type complexes are preferably used, and among them, it is particularly preferable to use a crosslinked complex.
Specifically, methylenebis {1,1 ′-(2-methyl-4-phenyldihydroazulenyl)} zirconium dichloride, methylenebis {1,1 ′-(2-ethyl-4-phenyldihydroazulenyl)} zirconium dichloride. , Methylenebis {1,1 ′-(4-phenyldihydroazurenyl)} zirconium dichloride, methylenebis {1,1 ′-(4-naphthyldihydroazurenyl)} zirconium dichloride, ethylenebis {1,1 ′-(2- Methyl-4-phenyldihydroazurenyl)} zirconium dichloride, ethylenebis {1,1 ′-(2-ethyl-4-phenyldihydroazurenyl)} zirconium dichloride, ethylenebis {1,1 ′-(4-phenyldihydro) Azulenyl)} zirconium dichloride, ethylenebis {1,1 ′-(4 Naphthyldihydroazurenyl)} zirconium dichloride, isopropylidenebis {1,1 ′-(2-methyl-4-phenyldihydroazurenyl)} zirconium dichloride, isopropylidenebis {1,1 ′-(2-ethyl-4-) Phenyldihydroazurenyl)} zirconium dichloride, isopropylidenebis {1,1 ′-(4-phenyldihydroazurenyl)} zirconium dichloride, isopropylidenebis {1,1 ′-(4-naphthyldihydroazurenyl)} zirconium dichloride , Dimethylsilylenebis {1,1 ′-(2-methyl-4-phenyldihydroazulenyl)} zirconium dichloride, dimethylsilylenebis {1,1 ′-(2-ethyl-4-phenyldihydroazurenyl)} zirconium dichloride , Dimethylsilylenebis {1,1 ′-(4-Phenyldihydroazurenyl)} zirconium dichloride, dimethylsilylenebis {1,1 ′-(4-naphthyldihydroazurenyl)} zirconium dichloride, diphenylsilylenebis {1,1 ′-(2 -Methyl-4-phenyldihydroazurenyl)} zirconium dichloride, diphenylsilylenebis {1,1 ′-(2-ethyl-4-phenyldihydroazurenyl)} zirconium dichloride, diphenylsilylenebis {1,1 ′-(4 -Phenyldihydroazurenyl)} zirconium dichloride, diphenylsilylenebis {1,1 ′-(4-naphthyldihydroazurenyl)} zirconium dichloride, and the like.
Among these, dimethylsilylene bis {1,1 ′-(2-methyl-4-phenyldihydroazulenyl)} zirconium dichloride and dimethylsilylene bis {1,1 ′-(2-ethyl-4-phenyldihydroazule) are particularly preferred. Nil)} zirconium dichloride is preferably used. In this case, the ratio of each position irregular unit can be easily controlled within the scope of the present invention, and the requirement (e) described later is satisfied (the isotactic triad fraction is 97%). A propylene-based polymer can be obtained.

The promoter component includes aluminoxanes such as methylaluminoxane, isobutylaluminoxane, methylisobutylaluminoxane, Lewis acid such as triphenylborane, tris (pentafluorophenyl) borane, magnesium chloride, dimethylanilinium tetrakis (pentafluorophenyl). ) An ionic compound such as borate can be exemplified. These promoter components can also be used in the presence of other organoaluminum compounds such as trialkylaluminum such as trimethylaluminum, triethylaluminum and triisobutylaluminum.
The mm fraction (isotactic triad fraction) in the entire polymer chain of the propylene polymer according to the present invention is expressed by the following [Equation 1]. By the way, in the partial structure (II), as a result of 1,3-insertion, only one methyl group derived from the propylene monomer disappears.

In this formula, ΣΙCH ₃ represents the area of all methyl groups (all peaks at 19-22 ppm of chemical shift). A <1>, A <2>, A <3>, A <4>, A <5>, A <6>, A <7>, A <8> and A <9> are respectively 42.3 ppm, 35.9 ppm, 38.6 ppm, 30.6 ppm, 36.0 ppm, 31.5 ppm, 31.0 ppm, 37.2 ppm, 27.4 ppm peak area, part in the above formula [Chemical Formula 2] The abundance ratio of carbon shown in the structures (Ι) and (ΙΙ) is shown.
The ratio of 2,1-inserted propylene and the ratio of 1,3-inserted propylene with respect to the total propylene insertion were calculated by the following equations.

Next, in the present invention, the propylene polymer, the melting point of the polymer Tm [° C.], also the water vapor permeability at the shaping of the polymer into a film ^{A [g / m 2 / 24hr} ] In this case, it is preferable that Tm and A satisfy the following relational expression (1).
(−0.20) · Tm + 35 ≦ A ≦ (−0.33) · Tm + 60 ·· Equation (1)

The water vapor permeability can be measured by JIS K7129 (1992) “Test method for water vapor permeability of plastic films and sheets”. In this measurement, an infrared sensor method is adopted as a test method, and a test temperature of 40 ± 0.5 ° C. and a relative humidity (90 ± 2)% RH are adopted as test conditions.
The propylene-based polymer within the range of the above formula (1) exhibits moderate water vapor permeability. Moderate water vapor permeability facilitates the penetration of saturated steam used for molding into the foamed particles during molding, thereby increasing the secondary foamability of the foamed particles and eliminating voids between the foamed particles. Or manufacture of few polypropylene resin foaming moldings becomes easy.

  Also, as a method for producing polypropylene resin expanded particles, a method in which resin particles are dispersed in water and impregnated with a foaming agent and then discharged from high temperature and pressure to low pressure to form expanded particles. In this case, the proper water vapor permeability facilitates the penetration of water and the foaming agent into the resin particles. As a result, water and the foaming agent are uniformly dispersed in the resin particles, the uniformity of the bubble diameter of the obtained foamed particles can be improved, and the expansion ratio can be improved.

  The water vapor permeability (A) is expressed in relation to the melting point (Tm) of the propylene-based polymer because the foaming temperature during the production of the foamed particles and the saturated steam temperature during the in-mold molding are generally This is based on the fact that the higher the melting point (Tm) of the propylene-based polymer that is the base resin, the higher the melting point (Tm), and the lower the melting point (Tm).

  When the water vapor permeability (A) is lower than [(−0.20) · Tm + 35], the permeability of the water vapor or the foaming agent to the base resin becomes inferior, and conversely [(−0.33 ) · Tm + 60], the water vapor permeability into the base resin becomes too good, and in any case, the dispersion of water and foaming agent in the resin particles becomes uneven in the process of producing the foam particles. This tends to reduce the uniformity of the bubble diameter of the resulting expanded particles. Moreover, there exists a possibility that the compression strength of the said polypropylene resin foaming molding obtained by shape | molding this expanded particle may fall, or distortion recovery property may fall. In particular, when the water vapor permeability (A) exceeds [(−0.33) · Tm + 60], coarse bubbles may be mixed in the obtained foamed particles.

  A propylene polymer in which the melting point (Tm) and the water vapor permeability (A) satisfy the relationship of the formula (1) can be obtained by selecting an appropriate catalyst in producing the polymer. Specifically, among the above metallocene catalysts, it can be suitably obtained by using bridged bis {1,1 '-(4-hydroazurenyl)} zirconium dichloride as a metal complex component. Preferred examples of such metal complex components are as described above.

In the present invention, the melting point (Tm) of the propylene polymer is generally 125 ° C. to 165 ° C., preferably 130 ° C. to 160 ° C., and more preferably 141 ° C. to 158 ° C.
For the melting point (Tm), “when melting temperature is measured after performing a certain heat treatment” described in JIS K7121 (1987) is adopted (the heating rate and cooling rate in the condition adjustment of the test piece are , Both adopt 10 ° C./min), use a heat flux DSC apparatus to draw a DSC curve at a heating rate of 10 ° C./min, and adopt the peak of the melting peak on the obtained DSC curve. If multiple vertices are observed, the one with the highest melting peak based on the baseline on the high temperature side is adopted, and if there are multiple vertices with the highest melting peak, the arithmetic average value thereof is used. Is adopted.

  In general, the melting point (Tm) of the propylene-based polymer can be increased as the proportion of the structural units obtained from the comonomer is decreased and as the proportion of each of the irregular units is decreased.

The propylene polymer satisfying the requirements (a) and (b) can be obtained using the metallocene catalyst.
In addition, the polypropylene resin foam molded article of the present invention is obtained by filling, for example, a mold with foamed particles having a propylene polymer having the above requirements (a) and (b) as a base resin and heating. After being foamed and cooled, it can be taken out of the mold and manufactured.

Moreover, the polypropylene resin foam molding of this invention has the said requirements (c).
The requirement (c) indicates the relationship between moisture permeability and density in the polypropylene resin foam molded article.
That is, the polypropylene resin foam molded article has a density X of 0.008 to 0.052 g / cm ³ , and a water vapor permeability measured in accordance with ASTM E-96 is Y [g / m ² / hr]. When the density of the foamed molded product is X [g / cm ³ ], Y and X satisfy the following relational expression (2).
Y <= (43.6) * X < ² >-(4.5) * X + 0.15 Formula (2)

If the moisture permeability Y and density X of the polypropylene resin foam molded product do not satisfy the relational expression (2), the moisture permeability of the polypropylene resin foam molded product is increased, and the heat insulating material or building material is used. There is a possibility that it cannot be used for various applications such as structural members and packaging materials.
In the polypropylene resin foam molded article, the moisture permeability Y is smaller as the density of the molded article is higher. Accordingly, in the above equation (2), the moisture permeability Y is expressed by a relational expression with the density X of the molded body. Further, the moisture permeability Y indicates a smaller numerical value as the adhesion between the expanded particles is higher. In the present invention, the above equation (2) is empirically derived from the relationship between the density and moisture permeability of a conventional polypropylene resin foam molded article, and the moisture permeability (Y The polypropylene-based resin foam molded article showing a lower moisture permeability than the conventional one.

  The polypropylene resin foam molded article satisfying the above formula (2) is, for example, a foam particle having a propylene polymer satisfying the above requirements (a) and (b) as a base resin, and has a closed cell ratio. (Measurement method is according to the method described in paragraph No. “0030” of JP-A-11-287277) 80% or more, preferably 85-100% of expanded particles are used between the expanded particles during in-mold molding. It can be manufactured by sufficiently expanding and molding so as to fill the voids.

The density X of the polypropylene resin foam molded article of the present invention is 0.008 to 0.052 g / cm ³ . When the density X exceeds 0.052 g / cm ³ , there is a possibility that the preferable characteristics of the foam such as lightness, cushioning properties, and heat insulating properties cannot be exhibited sufficiently.
On the other hand, when the density X is smaller than 0.008 g / cm ³ , the closed cell ratio tends to be small, and mechanical properties such as bending strength and compressive strength may be insufficient.
From the above viewpoint, the density X is preferably 0.01 to 0.045 g / cm ³ (Claim 5). In this case, the polypropylene-based resin foam molded article has both mechanical strength and light weight, and can obtain an effect of excellent surface appearance such as smoothness and glossiness. Therefore, in this case, the polypropylene resin foamed molded article is particularly suitable for, for example, a heat insulating material for construction, a member for automobiles, a helmet core material, a buffer packaging material, and the like.
In addition, the density of the said polypropylene resin foaming molding means the apparent whole density defined by JISK7222 (1999).

Next, the propylene-based polymer preferably further has the following requirements (e) (Claim 3 ).
(E) The isotactic triad fraction measured by ¹³ C- NMR of the propylene unit chain part composed of a head-to-tail bond is 97% or more.

That is, in addition to the requirements (a) and (b) described above, ¹³ C- NMR (nuclear magnetic resonance) of a propylene unit chain part consisting of a head-to-tail bond is added to the propylene polymer used as the base resin. The isotactic triad fraction measured by the above method (ie, among the three propylene units in the polymer chain, each propylene unit is bonded head-to-tail and the direction of methyl branching in the propylene unit is the same) The ratio of propylene unit 3 chain) is 97% or more.

  The isotactic triad fraction is hereinafter referred to as mm fraction. When the mm fraction is 97% or more, the mechanical properties of the propylene polymer are higher, and as a result, the mechanical properties such as rigidity of the polypropylene resin foamed molded product are higher. be able to. More preferably, the mm fraction is 98% or more.

Next, the propylene polymer preferably further has the following requirement (f) (Claim 4 ).
(F) The melt flow rate is 0.5 to 100 g / 10 minutes.

  In this case, the expanded particles can be produced while maintaining industrially useful production efficiency. Furthermore, the polypropylene resin foamed molded article obtained from the foamed particles can obtain an effect that its mechanical properties are excellent.

  When the melt flow rate (MFR) is less than 0.5 g / 10 min, the production efficiency of the foamed particles, particularly the productivity during melt kneading described later, may be reduced. On the other hand, when it exceeds 100 g / 10 minutes, there exists a possibility that mechanical properties, such as the compression strength of the said polypropylene resin foaming molding obtained by shape | molding the said foaming particle, and tensile strength, may become low. Therefore, the MFR is more preferably 1.0 to 50 g / 10 minutes. More preferably, 1.0-30 g / 10min is good. The MFR means a melt mass flow rate measured according to the conditions described in Table 3 of JIS K6921-2 (1997).

Next, the polypropylene resin foam molding is obtained when 2 to 4 mg of a test piece cut out from the polypropylene resin foam molding is heated to 220 ° C. at a rate of 10 ° C./min by a differential scanning calorimeter. It is preferable that the first DSC curve has a crystal structure in which an intrinsic peak and a high temperature peak appear as endothermic peaks . At this time, heating by the differential scanning calorimeter is started from room temperature (20 to 45 ° C.).

That is, this means that the polypropylene resin foamed molded product has a part showing an endothermic peak (inherent peak) inherent to the base resin and a part showing a higher endothermic peak in the DSC curve. It means to form.
In this case, the polypropylene resin foamed molded product is further excellent in mechanical properties such as compressive strength and tensile strength.

The relationship between the two endothermic peak temperatures is not particularly limited, but the difference between the two endothermic peak temperatures is 10 to 25 ° C., which means that the foamed particles are not fused during heating during in-mold molding. It is preferable from the point that it becomes easy. The temperature of the two endothermic peaks varies depending on the molecular structure of the base resin, the thermal history of the resin, the amount of foaming agent, the foaming temperature, the foaming pressure, etc. Generally, when foaming is performed on the high temperature side, the difference between the two endothermic peak temperatures is large. Become.
In the first DSC curve, in addition to the endothermic peak (inherent peak) inherent to the base resin, an expanded particle in which an endothermic peak (high temperature peak) at a higher temperature appears further is disclosed in, for example, JP-A-2002-200355 Can be produced by the method described in the above, and conditions for foaming resin particles having a propylene-based polymer as a base resin, specifically, the temperature, pressure until release to a low-pressure atmosphere, It is obtained by controlling time and the like.

  Moreover, in this invention, as long as it is a range which does not impair the effect of this invention with respect to the said propylene-type polymer as base resin, as above-mentioned, another polymer component and an additive can be mixed.

Examples of the other polymer components include high-density polyethylene, low-density polyethylene, and ethylene-based resins such as linear low-density polyethylene that is a copolymer of ethylene and α-olefin (4 or more carbon atoms); polybutene resin; Ethylene-propylene rubber; ethylene-propylene-diene rubber; hydrogenated block formed by saturating at least part of ethylene double bonds of styrene-diene block copolymer or styrene-diene block copolymer by hydrogenation Examples thereof include styrene-based thermoplastic elastomers such as copolymers; graft modified products of these resins, elastomers or rubbers with acrylic acid-based monomers.
In the present invention, these resins, elastomers, rubbers or modified products thereof can be used alone or in combination of two or more.

  As said additive, various additives, such as a foam nucleating agent, a coloring agent, an antistatic agent, and a lubricant, can be added. These are usually added together during the melt kneading described later and contained in the resin particles.

  The above foaming nucleating agents include inorganic compounds such as talc, calcium carbonate, silica, titanium oxide, gypsum, zeolite, borax, zinc borate, aluminum hydroxide, carbon, phosphate nucleating agent, phenolic nucleating agent. And organic nucleating agents such as amine nucleating agents. The addition amount of these various additives varies depending on the purpose of addition, but is 15 parts by weight or less, preferably 8 parts by weight or less, and more preferably 5 parts by weight or less based on 100 parts by weight of the base resin of the present invention. preferable.

  When the other polymer component or additive is mixed with the base resin, it can be performed by mixing a liquid and a solid or by mixing solids, but generally melt kneading is used. That is, for example, the base resin and other components are kneaded at a desired temperature using various kneaders such as a roll, a screw, a Banbury mixer, a kneader, a blender, and a mill. Molded into resin particles of a size suitable for manufacturing.

  The resin particles are melted and kneaded in the extruder, and then the kneaded product is discharged in a string form from a die having a minute hole attached to the tip of the extruder, and then the specified weight or size is determined by a cutting machine equipped with a take-up machine. A columnar pellet can be obtained by cutting into two pieces.

  In general, when the weight of one resin particle is 0.1 to 20 mg, there is no problem in the production of foamed particles obtained by heating and foaming the resin particles. When the weight of one resin particle is in the range of 0.2 to 10 mg and the variation in the weight between the particles is further small, the production of the expanded particles is facilitated, and the density variation of the obtained expanded particles is also reduced. , The filling property of the expanded particles into the mold is improved.

  As a method for obtaining foamed particles from the resin particles, a method in which resin particles produced as described above are impregnated with a volatile foaming agent and then heated and foamed, specifically, for example, Japanese Patent Publication No. 49-2183. 56-1344, West German Patent Publication No. 1285722, No. 2107683, etc. can be used.

That is, first, resin particles are put together with a dispersion medium and a volatile foaming agent in a pressure vessel that can be sealed and opened, and heated above the softening temperature of the base resin to impregnate the resin particles with the volatile foaming agent.
Thereafter, the foamed particles can be obtained by discharging the contents in the sealed container from the sealed container to a low-pressure atmosphere. Usually, after that, it is dried and then used for in-mold molding.

In the method for producing the foamed particles, if the decomposable foaming agent is kneaded in advance in the resin particles, the foamed particles can be obtained without blending the foaming agent in the pressure vessel.
As the above decomposable foaming agent, any gas can be used as long as it decomposes at the foaming temperature of the resin particles to generate gas. Specifically, sodium bicarbonate, ammonium carbonate, an azide compound, an azo compound, etc. are mentioned, for example.

  Moreover, it is preferable to use water, alcohol or the like as the dispersion medium. Furthermore, poorly water-soluble inorganic substances such as aluminum oxide, tricalcium phosphate, magnesium pyrophosphate, zinc oxide, kaolin, mica, talc, polyvinyl pyrrolidone, polyvinyl alcohol, methylcellulose, etc., so that the resin particles are uniformly dispersed in the dispersion medium It is preferable to use an anionic surfactant such as a water-soluble polymeric protective colloid agent, sodium dodecylbenzenesulfonate, sodium alkanesulfonate or the like alone or in admixture of two or more.

Furthermore, a dispersion strengthening agent that strengthens the dispersing power of the dispersing agent (which prevents the resin particles from being fused in the container even if the amount of the dispersing agent added is small) may be added to the dispersion medium. In particular, when producing low-expanded expanded particles having an apparent density of 100 g / L or more, it is preferable to use a dispersion strengthening agent.
As such a dispersion strengthening agent, an inorganic substance that can be dissolved in at least 1 mg or more in 100 cc of water at 40 ° C., wherein at least one of the anion or cation of the compound is divalent or trivalent, is used. be able to. Examples of such inorganic substances include magnesium chloride, magnesium nitrate, magnesium sulfate, aluminum chloride, aluminum nitrate, aluminum sulfate, iron chloride, iron sulfate, and iron nitrate.

  When releasing resin particles to a low-pressure atmosphere, in order to facilitate the release, the same pressure as in the above is introduced by introducing the same inorganic gas or volatile foaming agent into the sealed container from the outside. It is preferable to hold.

Next, the foamed molded product of the present invention can be obtained by heating the above-mentioned foamed particles to cause secondary foaming, and after fusing them together, cooling them.
In this case, molds with various conditions are used.

  For example, as shown in Japanese Examined Patent Publication No. 46-38359, after filling foamed particles into a cavity made up of a pair of concave and convex molds under atmospheric pressure or reduced pressure, the volume of the mold cavity is reduced by 5 to 70%. A compression molding method in which compression is performed in the same manner, and then a heating medium such as steam is introduced into the cavity to heat-fuse the foamed particles.

  Further, for example, as shown in Japanese Patent Publication No. 51-22951, the foamed resin particles are pretreated with one or more volatile foaming agents or inorganic gases to increase the secondary foaming power of the foamed resin particles, Next, the foamed resin particles are filled in a cavity made up of a pair of concave and convex molds under atmospheric pressure or reduced pressure while maintaining the secondary foaming force, and then a heating medium is introduced into the mold cavity to obtain the foamed resin particles. There is also a pressure aging molding method in which the material is heat-sealed.

  For example, as disclosed in Japanese Patent Publication No. 4-46217, a mold cavity pressurized to a pressure higher than the atmospheric pressure with a compressed gas is filled with foamed resin particles pressurized to a pressure higher than the pressure, and then the mold cavity is filled. There is also a compression-fill molding method in which a heat medium such as steam is introduced into the tee to heat-fuse the foamed resin particles.

  Further, for example, as shown in Japanese Patent Publication No. 6-49795, a mold comprising a pair of concave and convex molds under atmospheric pressure or reduced pressure using foamed resin particles having a high secondary foaming force obtained under special conditions. There is also an atmospheric pressure filling molding method in which foamed resin particles are filled into a tee and then a heat medium such as steam is introduced into a mold cavity to heat-fuse the foamed resin particles. Further, as shown in, for example, Japanese Examined Patent Publication No. 6-22919, it can be formed by a combination of the above methods.

  In addition, as a typical application of the polypropylene resin foam molded article of the present invention, a heat insulating material in the building field can be cited as a typical example. It is preferably used as an automobile interior material by being integrated with a skin material.

  Examples of the automobile interior material include a dashboard, console box, instrument panel, door panel, door trim, ceiling material, pillar interior material, sun visor, armrest, headrest and the like. In addition to automotive applications, it can be widely used as a core material for helmets, structural materials such as ships, airplanes, and railway vehicles, and various cushioning materials.

  The various skin materials are not particularly limited. For example, polyolefin-based elastomer sheet, OPS (biaxially stretched polystyrene sheet), polystyrene resin film such as high heat resistant OPS, HIPS, CPP (unstretched polypropylene film), OPP Examples thereof include polypropylene resin films such as (biaxially stretched polypropylene film), various films such as polyethylene resin films and polyester resin films, and various skin materials such as felt and nonwoven fabric. The skin material may be a molded body such as an injection molded body.

  Next, examples of the present invention will be described.

[Manufacture of base resin]
First, the propylene-based polymer as the base resin of the expanded particles was synthesized by the method shown in the following Production Examples 1-8.

Production Example 1
(I) Synthesis of [dimethylsilylenebis {1,1 ′-(2-methyl-4-phenyl-4-hydroazurenyl)} zirconium dichloride] The following reactions are all carried out in an inert gas atmosphere. A dried and purified solvent was used.

(A) Synthesis of racemic / meso mixture 2.22 g of 2-methylazulene synthesized according to the method described in JP-A-62-207232 was dissolved in 30 mL of hexane, and 15.6 mL of cyclohexane-diethyl ether solution of phenyllithium ( 1.0 equivalent) was added in small portions at 0 ° C.
The solution was stirred at room temperature for 1 hour, cooled to -78 ° C, and 30 mL of tetrahydrofuran was added.

  Subsequently, after adding 0.95 mL of dimethyldichlorosilane, it heated up to room temperature, and also heated at 50 degreeC for 90 minutes. Thereafter, a saturated aqueous solution of ammonium chloride was added, the organic layer was separated, dried over sodium sulfate, and the solvent was distilled off under reduced pressure.

The obtained crude product was purified by silica gel column chromatography (hexane: dichloromethane = 5: 1) to give bis {1,1 ′-(2-methyl-4-phenyl-1,4-dihydroazurenyl). ) 1.48 g of dimethylsilane was obtained.
786 mg of the bis {1,1 ′-(2-methyl-4-phenyl-1,4-dihydroazurenyl) dimethylsilane obtained above was dissolved in 15 mL of diethyl ether, and hexane of n-butyllithium was added at −78 ° C. 1.98 mL of the solution (1.68 mol / L) was added dropwise, the temperature was gradually raised to room temperature, and then the mixture was stirred at room temperature for 12 hours. The solid obtained by distilling off the solvent under reduced pressure was washed with hexane and dried under reduced pressure.

Furthermore, 20 mL of a toluene-diethyl ether mixed solvent (40: 1) was added, 325 mg of zirconium tetrachloride was added at −60 ° C., the temperature was gradually raised, and the mixture was stirred at room temperature for 15 minutes.
The resulting solution was concentrated under reduced pressure, and reprecipitated by adding hexane, whereby racemic dimethylsilylenebis {1,1 ′-(2-methyl-4-phenyl-4-hydroazurenyl)} zirconium dichloride was prepared. A 150 mg / meso mixture was obtained.

(B) Separation of racemic body 887 mg of a racemic / meso mixture obtained by repeating the above reaction was put in a glass container, dissolved in 30 mL of dichloromethane, and irradiated with a high pressure mercury lamp for 30 minutes. Thereafter, dichloromethane was distilled off under reduced pressure to obtain a yellow solid.
7 mL of toluene was added to this solid, stirred, and allowed to stand to separate a yellow solid as a precipitate. The supernatant was removed, and the solid was dried under reduced pressure to obtain 437 mg of a racemate consisting of dimethylsilylene bis {1,1 ′-(2-methyl-4-phenyl-4-hydroazurenyl)} zirconium dichloride.

(Ii) Catalyst synthesis (a) Treatment of catalyst carrier 135 mL of demineralized water and 16 g of magnesium sulfate were placed in a glass container and stirred to obtain a solution. After adding 22.2 g of montmorillonite (“Kunipia-F” manufactured by Kunimine Kogyo Co., Ltd.) to this solution, the temperature was raised and kept at 80 ° C. for 1 hour.
Next, after adding 300 mL of demineralized water, the solid content was separated by filtration. After adding 46 mL of demineralized water, 23.4 g of sulfuric acid, and 29.2 g of magnesium sulfate to this solid content, the temperature was raised and the mixture was heated and refluxed for 2 hours, and then 200 mL of demineralized water was added and filtered.
Further, 400 mL of demineralized water was added and filtration was performed twice. Thereafter, the solid was dried at 100 ° C. to obtain chemically treated montmorillonite as a catalyst support.

(B) Preparation of catalyst component After the inside of a stirring autoclave having an internal volume of 1 liter was sufficiently substituted with propylene, 230 mL of dehydrated heptane was introduced, and the system temperature was maintained at 40 ° C.
Here, 10 g of the chemically treated montmorillonite prepared as described above as a catalyst support was suspended in 200 mL of toluene and added.

  Further, a racemic dimethylsilylene bis {1,1 ′-(2-methyl-4-phenyl-4-hydroazurenyl)} zirconium dichloride prepared in a separate container (0.15 mmol) and triisobutylaluminum (3 mmol) Were mixed in toluene (total 20 mL) and added to the autoclave.

  Thereafter, propylene was introduced at a rate of 10 g / hr for 120 minutes, and then the polymerization reaction was continued for 120 minutes. Then, the solvent was distilled off under a nitrogen atmosphere and dried to obtain a solid catalyst component. This catalyst component contained 1.9 g of polymer per 1 g of the solid component.

(Iii) Polymerization of propylene (propylene homopolymerization)
After sufficiently replacing the inside of the stirring type autoclave with an internal volume of 200 L with propylene, 45 kg of sufficiently dehydrated liquefied propylene was introduced. To this, 500 mL (0.12 mol) of hexane solution of triisobutylaluminum and hydrogen (3NL) were introduced, and the temperature inside the autoclave was raised to 70 ° C.
Thereafter, the solid catalyst component (1.7 g) was injected with argon to start polymerization, and a polymerization reaction was carried out for 3 hours.

Thereafter, 100 mL of ethanol was injected into the reaction system to stop the reaction, and the residual gas component was purged to obtain 14.1 kg of polymer.
This polymer has a structural unit derived from propylene of 100 mol%, that is, a propylene homopolymer. This satisfies the requirement (a) for the propylene polymer.

This polymer has an MFR (melt flow rate) of 10 g / 10 min, an isotactic triad fraction of 99.7%, a melting point (Tm) of 146 ° C., and the requirements for the propylene polymer (e) And (f) is satisfied. Furthermore, the ratio of the position irregular unit based on 2,1-insertion is 1.32%, the ratio of the position irregular unit based on 1,3-insertion is 0.08%, and the requirements regarding the propylene-based polymer ( b) is satisfied.
Hereinafter, the propylene-based polymer obtained here is referred to as “polymer 1”.

(Iv) Measurement of water vapor transmission rate The polymer 1 obtained above was molded into a film having a thickness of 25 microns, and the water vapor transmission rate A was measured according to the method described in JIS K7129 (the same applies to the following production examples). was ^{.5 (g / m 2 / 24hr} ).
In addition, since this polymer 1 has a melting point (Tm) of 146 ° C., from the above formula (1), A should be within the range of 5.8 ≦ A ≦ 11.8, but was within that range. .

Production Example 2 (propylene / ethylene copolymer)
After thoroughly replacing the inside of the stirred autoclave with an internal volume of 200 L with propylene, introduce 60 L of purified n-heptane, add 500 mL (0.12 mol) of hexane solution of triisobutylaluminum, and raise the inside of the autoclave to 70 ° C. Warm up. Thereafter, the solid catalyst component (9.0 g) was added, and a mixed gas of propylene and ethylene (propylene: ethylene = 97.5: 2.5; weight ratio) was introduced so that the pressure became 0.7 MPa. Then, the polymerization was started, and the polymerization reaction was carried out for 3 hours under these conditions.

Thereafter, 100 mL of ethanol was injected into the reaction system to stop the reaction, and the residual gas component was purged to obtain 9.3 kg of polymer.
In this polymer, 97.0 mol% of structural units obtained from propylene and 3.0 mol% of structural units obtained from ethylene are present. This satisfies the above requirement (a).

  Further, this polymer has an MFR of 14 g / 10 min, an isotactic triad fraction of 99.2%, a melting point (Tm) of 141 ° C., and satisfies the above requirements (e) and (f). Furthermore, the ratio of the position irregular unit based on 2,1-insertion is 1.06%, and the ratio of the position irregular unit based on 1,3-insertion is 0.16%, which satisfies the requirement (b). Yes. Hereinafter, the polymer obtained here is referred to as “polymer 2”.

Also, for the polymer 2, as in the polymer 1, the water vapor permeability A after molding into a film was ^{12.0 (g / m 2 / 24hr} ).
In addition, since this polymer 2 has a melting point (Tm) of 141 ° C., from the above formula (1), A should be within the range of 6.8 ≦ A ≦ 13.5, but was within that range. .

Production Example 3 (Propylene / 1-butene copolymerization)
After thoroughly replacing the inside of the stirred autoclave with an internal volume of 200 L with propylene, introduce 60 L of purified n-heptane, add 500 mL (0.12 mol) of hexane solution of triisobutylaluminum, and raise the inside of the autoclave to 70 ° C. Warm up. Thereafter, the solid catalyst component (9.0 g) was added, and a mixed gas of propylene and 1-butene (propylene: 1-butene = 90: 10; weight ratio) was introduced so that the pressure was 0.6 MPa. Then, the polymerization was started, and the polymerization reaction was carried out for 3 hours under these conditions.

Thereafter, 100 mL of ethanol was injected into the reaction system to stop the reaction, and the residual gas component was purged to obtain 8.6 kg of polymer.
In this polymer, 95.4 mol% of structural units obtained from propylene and 4.6 mol% of structural units obtained from 1-butene are present. This satisfies the requirement (a) for the propylene polymer.

  Further, this polymer has an MFR of 6 g / 10 min, a melting point (Tm) of 142 ° C., and an isotactic triad fraction of 99.3%, and satisfies the requirements (e) and (f) for the propylene polymer. Satisfies. Furthermore, the ratio of the position irregular unit based on 2,1-insertion is 1.23%, the ratio of the position irregular unit based on 1,3-insertion is 0.09%, and the requirements regarding the propylene-based polymer ( b) is satisfied. The polymer obtained here is referred to as “Polymer 3”.

Further, the polymer 3 was formed into a film in the same manner as in the polymer 1 was examined the water vapor transmission rate A, was ^{11.5 (g / m 2 / 24hr} ).
Since the melting point (Tm) of this polymer 3 is 142 ° C. as described above, the water vapor permeability A should be in the range of 6.6 ≦ A ≦ 13.1 from the above formula (1). It was within that range.

Production Example 4 (propylene homopolymerization)
After thoroughly replacing the inside of the 200L stirred autoclave with propylene, 60L of purified n-heptane was introduced, 45g of diethylaluminum chloride and 11.5g of titanium trichloride catalyst manufactured by Marubeni Solvay were introduced into the propylene atmosphere. did. Further, propylene was introduced into the autoclave at a rate of 9 kg / hr for 4 hours at an autoclave temperature of 65 ° C. while maintaining the hydrogen concentration in the gas phase at 7.0 vol%.

  After the introduction of the mixed gas was stopped, the reaction was continued for another hour, 100 mL of butanol was added to the reaction system to stop the reaction, and the remaining gas components were purged to obtain 30 kg of polymer. Hereinafter, the polymer obtained here is referred to as “polymer 4”.

  This polymer 4 contains 100 mol% of structural units obtained from propylene, that is, a propylene homopolymer. This satisfies the requirement (a) for the propylene polymer.

Polymer 4 had an MFR of 7 g / 10 min, a melting point (Tm) of 160 ° C., and an isotactic triad fraction of 97.0%.
In addition, in Polymer 4, the ratio of position irregular units based on 2,1-insertion was 0%, and the ratio of position irregular units based on 1,3-insertion was 0%. That is, the polymer 4 did not satisfy the requirement (b) regarding the propylene polymer.

Similar to the polymer 1 was examined the water vapor transmission rate A when the molded polymer 4 in the film was ^{10.0 (g / m 2 / 24hr} ).
In addition, since the melting point (Tm) of the polymer 4 is 160 ° C., the water vapor permeability A should be within the range of 3.0 ≦ A ≦ 7.2 from the above formula (1). It was not in.

Production Example 5 (propylene / ethylene copolymer)
After thoroughly replacing the inside of the stirred autoclave with an internal volume of 200 L with propylene, 60 L of purified n-heptane was introduced, and 7.5 g of diethylaluminum chloride (40 g) and a titanium trichloride catalyst manufactured by Marubeni Solvay Co. were placed in a propylene atmosphere. Introduced. Further, while maintaining the hydrogen concentration in the gas phase at 7.0% by volume, a mixed gas of propylene and ethylene (propylene: ethylene = 97.5: 2.5; weight ratio) at an autoclave internal temperature of 60 ° C. It introduced so that a pressure might be set to 0.7 Mpa.

After the introduction of the mixed gas was stopped, the reaction was continued for another hour, 100 mL of butanol was added to the reaction system to stop the reaction, and the remaining gas components were purged to obtain 32 kg of polymer. Hereinafter, the polymer obtained here is referred to as “polymer 5”.
In this polymer 5, 96.1 mol% of structural units obtained from propylene and 3.9 mol% of structural units obtained from ethylene are present. This satisfies the requirement (a) for the propylene polymer.

Polymer 5 had an MFR of 12 g / 10 min, a melting point (Tm) of 146 ° C., and an isotactic triad fraction of 96.0%.
In addition, in Polymer 5, the ratio of position irregular units based on 2,1-insertion was 0%, and the ratio of position irregular units based on 1,3-insertion was 0%. That is, the polymer 5 did not satisfy the requirement (b) regarding the propylene polymer.

Similar to the polymer 1 was examined the water vapor transmission rate A when the molded polymer 5 in the film was ^{15.0 (g / m 2 / 24hr} ).
In addition, since the melting point (Tm) of the polymer 5 is 146 ° C., the water vapor permeability A should be within the range of 5.8 ≦ A ≦ 11.8 from the above formula (1). It wasn't.

Production Example 6 (Propylene / 1-butene copolymerization)
After thoroughly replacing the interior of the stirred autoclave with an internal volume of 200 L with propylene, 60 L of purified n-heptane was introduced, 45 g of diethylaluminum chloride, and 15.0 g of titanium trichloride catalyst manufactured by Marubeni Solvay were introduced in a propylene atmosphere. did. Further, while maintaining the hydrogen concentration in the gas phase at 7.0% by volume, a mixed gas of propylene and 1-butene at an internal temperature of the autoclave of 60 ° C. (propylene: 1-butene = 90: 10, weight ratio) Was introduced so that the pressure became 0.6 MPa.

After the introduction of the mixed gas was stopped, the reaction was continued for another hour, 100 mL of butanol was added to the reaction system to stop the reaction, and the remaining gas components were purged to obtain 24 kg of polymer. Hereinafter, the polymer obtained here is referred to as “polymer 6”.
This polymer 6 contains 96.9 mol% of structural units obtained from propylene and 3.1 mol% of structural units obtained from 1-butene. This satisfies the requirement (a) for the propylene polymer.

Polymer 6 had an MFR of 8 g / 10 min, a melting point (Tm) of 150 ° C., and an isotactic triad fraction of 95.4%.
In addition, the ratio of the position irregular unit based on 2,1-insertion in polymer 6 was 0%, and the ratio of the position irregular unit based on 1,3-insertion was 0%. That is, the polymer 6 did not satisfy the requirement (b) regarding the propylene polymer.

Similar to the polymer 1 was examined the water vapor transmission rate A when the molded polymer 6 into a film was ^{16.2 (g / m 2 / 24hr} ).
Since the melting point (Tm) of the polymer 6 is 150 ° C., the water vapor transmission rate A should be within the range of 5.0 ≦ A ≦ 10.5 from the above formula (1). It was not in.

Production Example 7 (Propylene homopolymerization)
This was carried out by applying the method described in [Production of base resin 1] in the examples of JP-A-6-240041.
That is, after the inside of a stirring autoclave having an internal volume of 200 L is sufficiently substituted with propylene, 60 L of purified n-heptane is introduced, and 120 g of methylalumoxane (average oligomer degree 16) manufactured by Tosoh Akzo Co., Ltd. is disclosed. Rac-dimethylsilylenebis (2-methylindenyl) zirconium dichloride (150 mg) synthesized by the method described in Japanese Patent No. 268307 was introduced under a propylene atmosphere. Further, propylene was introduced into the autoclave at a rate of 7 kg / hr for 3 hours at an autoclave internal temperature of 40 ° C. while maintaining the hydrogen concentration in the gas phase at 0.5% by volume.

  After stopping the introduction of propylene, the reaction was continued for another hour, 100 mL of butanol was added to the reaction system to stop the reaction, and the residual gas component was purged to obtain 9.4 kg of polymer. This polymer has a structural unit obtained from propylene of 100 mol%, that is, a propylene homopolymer. This satisfies the requirement (a). Hereinafter, the polymer obtained here is referred to as “polymer 7”.

This polymer 7 has an MFR = 9, a melting point (Tm) of 150 ° C., an isotactic triad fraction of 94.4%, a ratio of position irregular units based on 2,1-insertion of 0.25%, 1 , 3-The percentage of irregular units based on insertion was below the detection limit, ie less than 0.005%.
That is, this does not satisfy the requirement (b).
In Table 2, which will be described later, the ratio of position irregular units based on 1,3 insertion of polymer 7 is shown as 0%.

Also, for the polymer 7, in the same manner as in the polymer 1 was examined the water vapor transmission rate A after being molded into a film was ^{4.8 (g / m 2 / 24hr} ).
Since the melting point (Tm) of this polymer 7 is 150 ° C., the above formula (1) indicates that A should be within the range of 5.0 ≦ A ≦ 10.5, but was outside that range.

Production Example 8 (Propylene homopolymerization)
After sufficiently replacing the interior of the stirred autoclave with an internal volume of 200 L with propylene, 60 L of purified n-heptane was introduced, and 120 g of methylalumoxane (average oligomer degree 16) manufactured by Tosoh Akzo Co., Ltd., a known method [H. H. Yamazaki et.al., “Chemistry Letters”, Japan, 1989, Vol. 18, p. 1853 (1989)] rac-dimethylsilylenebis (3-methylcyclopentadienyl) zirconium dichloride (100 mg) was introduced under a propylene atmosphere. Further, propylene was introduced into the autoclave at a rate of 7 kg / hr for 3 hours at an autoclave internal temperature of 40 ° C. while maintaining the hydrogen concentration in the gas phase at 0.5% by volume.

After stopping the introduction of propylene, the reaction was continued for an additional hour, 100 mL of butanol was added to the reaction system to stop the reaction, and the residual gas component was purged to obtain 5.6 kg of polymer. This polymer has a structural unit obtained from propylene of 100 mol%, that is, a propylene homopolymer. This satisfies the requirement (a). Hereinafter, the polymer obtained here is referred to as “polymer 8”.
This polymer 8 has an MFR = 20, a melting point (Tm) of 141 ° C., an isotactic triad fraction of 91.5%, a ratio of position irregular units based on 2,1-insertion of 2.1%, 1 The percentage of irregular units based on 3-insertion was 0.45%.
That is, this does not satisfy the requirement (b).

Also, for the polymer 8, in the same manner as in the polymer 1 was examined the water vapor transmission rate A after being molded into a film, was ^{13.8 (g / m 2 / 24hr} ).
Since this polymer 8 has a melting point (Tm) of 141 ° C., the above formula (1) indicates that A should be within the range of 6.8 ≦ A ≦ 13.5, but was outside that range.

[Production of expanded particles]
Next, Examples in which foamed particles are produced using the polymers 1 to 8 obtained in Production Examples 1 to 8 as the base resin will be described.

Example 1
65 mmφ obtained by adding an antioxidant (trade name “Yoshinox BHT” manufactured by Yoshitomi Pharmaceutical Co., Ltd., 0.05 wt% and product name “Irganox 1010” manufactured by Ciba Geigy, 0.10 wt%) to polymer 1 obtained in Production Example 1. A 1-mm diameter strand was extruded with a single screw extruder, cooled in a water tank, and then cut into a length of 2 mm to obtain fine pellets.

  1000 g of these pellets were placed in an autoclave with an internal volume of 5 liters together with 2500 g of water, 200 g of tricalcium phosphate and 0.2 g of sodium dodecylbenzenesulfonate, 140 g of isobutane was further added, and the temperature was raised to 137 ° C. over 60 minutes. For 30 minutes.

Thereafter, in order to maintain the pressure in the autoclave at a gauge pressure of 2.3 MPa, the valve at the bottom of the autoclave was opened while the compressed nitrogen gas was added from the outside, and the contents were released to the atmosphere.
After the foamed particles obtained by the above operation were dried, the bulk density was measured and found to be 10 g / L. Further, the foamed particles had an average of 340 μm and were very uniform. Hereinafter, the expanded particles are referred to as “expanded particles A”.

  The average cell diameter of the foamed particles is determined by observing a cross section of the foamed particles cut through the center of the randomly selected foamed particles with a microscope (or showing this cross section on the screen). In this example, 50 bubbles are randomly selected and the average value of their diameters (maximum length) is shown.

Example 2
Expanded particles were produced in the same manner as in Example 1 except that the polymer 1 obtained in Production Example 1 was used and the amount of isobutane added was 135 g.
The foamed particles had a bulk density of 14 g / L. Further, the foamed particles had an average of 310 μm and were very uniform. Hereinafter, the expanded particles are referred to as “expanded particles B”.

Example 3
Expanded particles were produced in the same manner as in Example 1 except that the polymer 1 obtained in Production Example 1 was used, the foaming temperature was 135 ° C., and the addition amount of isobutane was 125 g.
The expanded particles had a bulk density of 26 g / L. Further, the bubbles of the foamed particles had an average of 280 μm and were very uniform. Hereinafter, the expanded particles are referred to as “expanded particles C”.

Example 4
Expanded particles were produced in the same manner as in Example 1 except that the polymer 2 obtained in Production Example 2 was used, the foaming temperature was 130 ° C., and the amount of isobutane added was 125 g.
The expanded particles had a bulk density of 26 g / L. Further, the foamed particles had an average of 300 μm and were very uniform. Hereinafter, the expanded particles are referred to as “expanded particles D”.

Example 5
Expanded particles were produced in the same manner as in Example 1 except that the polymer 3 obtained in Production Example 3 was used, the foaming temperature was 132 ° C., and the amount of isobutane added was 135 g.
The foamed particles had a bulk density of 14 g / L. Further, the foamed particles had an average of 300 μm and were very uniform. Hereinafter, the expanded particles are referred to as “expanded particles E”.

Comparative Example 1
Using the polymer 4 obtained in Production Example 4, the foaming temperature was 150 ° C., and the addition amount of isobutane was 140 g.
The foamed particles had a bulk density of 14 g / L. Moreover, the bubbles of the expanded particles had an average of 200 μm, and the variation was large. Hereinafter, the expanded particles are referred to as “expanded particles F”.

Comparative Example 2
Expanded particles were produced in the same manner as in Comparative Example 1 except that the polymer 5 obtained in Production Example 5 was used, the foaming temperature was 135 ° C., and the amount of isobutane added was 130 g.
The foamed particles had a bulk density of 14 g / L. Moreover, the bubbles of the expanded particles had an average of 180 μm, and the variation was large. Hereinafter, the expanded particles are referred to as “expanded particles G”.

Comparative Example 3
Expanded particles were produced in the same manner as in Comparative Example 2 except that the amount of isobutane added was 125 g.
The expanded particles had a bulk density of 26 g / L. In addition, the foamed particles had an average of 200 μm and had a large variation. Hereinafter, the expanded particles are referred to as “expanded particles H”.

Comparative Example 4
Except that the polymer 6 obtained in Production Example 6 was used, the foaming temperature was 140 ° C., and the amount of isobutane added was 135 g, foamed particles were obtained in the same manner as in Example 1 above.
The bulk density of the expanded particles was 14 g / L. Moreover, the bubbles of the expanded particles had an average of 180 μm, and the variation was large. Hereinafter, the expanded particles are referred to as “expanded particles I”.

Comparative Example 5
The same procedure as in Example 1 was conducted except that the polymer 7 obtained in Production Example 7 was used, the foaming temperature was 140 ° C., and the amount of isobutane added was 130 g. Thus, foamed particles were obtained.
The expanded particles had a bulk density of 26 g / L. Moreover, the bubbles of the expanded particles had an average of 220 μ and varied. Hereinafter, the expanded particles are referred to as “expanded particles J”.

Comparative Example 6
The same procedure as in Example 1 was carried out except that the polymer 8 obtained in Production Example 8 was used, the foaming temperature was 130 ° C., and the amount of isobutane added was 125 g.
The expanded particles had a bulk density of 26 g / L. In addition, the bubbles of the expanded particles had an average of 210 μm, and there were coarse bubbles. Hereinafter, the expanded particles are referred to as “expanded particles K”.
The above results are shown in Tables 1 and 2.

[Production of polypropylene resin foam moldings]
Next, using the foamed particles A to K obtained in Examples 1 to 5 and Comparative Examples 1 to 6, a polypropylene resin foam molded article is prepared.

Example 6
The foamed particles A obtained in Example 1 above are accommodated in a pressure-resistant container and placed at a normal temperature under pressurized air of 0.4 MPa (gauge pressure) for 6 hours to allow the pressurized air to penetrate into the foamed particles A. As a result, the internal pressure of the expanded particles A was increased, and the expanded particles A in a state where the internal pressure was 0.05 MPa higher than the atmospheric pressure were obtained. Next, the foamed particles A are cracked and filled in an aluminum mold by placing it in an air flow, and then the mold is completely closed, and then the mold chamber is heated through steam with a gauge pressure of 0.28 MPa. After cooling with water, the product was taken out from the mold and sufficiently dried to obtain a polypropylene resin foam molded article having a density of 0.011 g / cm ³ .
Further, a test piece having a length of 290 mm, a width of 290 mm, and a thickness of 10 mm was produced from this polypropylene resin foam molded article, and the moisture permeability was measured according to ASTM E96.

  In addition, a test piece having a length of 50 mm, a width of 50 mm, and a thickness of 25 mm was prepared from another molded body molded under the same molding conditions, and the test piece temperature was 23 ° C. and the compression speed was 10 mm / min in accordance with JIS K7220 (1999). A compression test was conducted under the conditions. Based on the compression test results obtained here, a stress-strain diagram was created (an example is shown in FIG. 1). From this figure, the stress (C in FIG. 1) at 50% compression (synonymous with 50% strain) was determined.

Furthermore, as a heat resistance test, a test piece having a length of 200 mm, a width of 30 mm, and a thickness of 12.5 mm was produced from another molded body molded under the same molding conditions, and at 110 ° C. according to JIS K6767 (1976). The heat shrinkage rate was measured and the heat resistance was judged according to the following criteria.
○: Dimensional shrinkage is less than 3%.
Δ: Dimensional shrinkage is 3% or more and 6% or less.
X: Dimensional shrinkage exceeds 6%.
The results are shown in Table 3.

Example 7
The foamed particles A obtained in Example 1 were filled in a mold made of aluminum using a compressed air with a hopper while being compressed with a compression ratio of 60%, and then the gauge pressure was applied to the mold chamber. After heat-molding through 0.28 MPa steam, water-cooling, it was taken out from the mold and sufficiently dried to obtain a polypropylene resin foam molded article having a density of 0.016 g / cm ³ . Further, in the same manner as in Example 6, test pieces were produced from these polypropylene resin foam molded articles, the moisture permeability was measured, and further a compression test and a heat resistance test were performed. The results are also shown in Table 3. The above-mentioned “compression ratio” means that the bulk density of uncompressed foam particles under atmospheric pressure is NPD (g / L), and the bulk density of foam particles in the mold filled in the mold is PD. When expressed as (g / L), it is expressed by the following formula (3).
Compression rate (%) = (PD−NPD) ÷ NPD × 100 Formula (3)

(Examples 8 to 19) and (Comparative Examples 7 to 24)
The type of foamed particles and molding conditions were changed as shown in Tables 3 to 7 to be described later, and a polypropylene resin foamed molded article was produced in the same manner as in Example 7 above.
Further, in the same manner as in Example 6, test pieces were produced from these polypropylene resin foam molded articles, the moisture permeability was measured, and further a compression test and a heat resistance test were performed.
The results are shown in Tables 3 to 7.

The molding vapor pressure in the following Tables 3 to 7 means a water vapor pressure that gives a molded product having a fusion degree of 80%.
Here, the degree of fusion refers to the ratio of particle breakage to the total number of both specimens obtained by rupturing a test piece prepared from a compact, visually measuring the number of particle breaks and the number of interparticle breaks in the cross section. (%).

As is known from Tables 3 to 7, the polypropylene resin foam molded articles obtained from Examples 6 to 19 have moisture permeability Y (g / m ² / hr) and density X (g / cm ³ ). The above relationship satisfies the relationship of the above formula (2), the moisture permeability is small, and the moisture resistance is excellent. It was also excellent in heat resistance and strength (50% compression stress). Therefore, it was excellent as a building member or a structural member for a vehicle.

Furthermore, when the polypropylene resin foamed molded products of Examples 6 to 13 were compared with those of Comparative Examples 7 to 9 and Comparative Examples 19 to 24, they all contained a polypropylene homopolymer as a base resin. However, in the polypropylene resin foam molded articles of Comparative Examples 7 to 9 and Comparative Examples 19 to 24, the relationship between the moisture permeability Y (g / m ² / hr) and the density X (g / cm ³ ) is the above formula. The relationship (2) is not satisfied. And when Examples 6-13, Comparative Examples 7-9, and Comparative Examples 19-24 are respectively compared with those having substantially the same molding conditions, the polypropylene resin foam molded bodies of Examples 6-13 are heat resistant. In addition to being excellent in strength, the moisture permeability was small compared to Comparative Examples 7 to 9 and Comparative Examples 19 to 24, and the moisture resistance was excellent.

Moreover, when the polypropylene resin foam molded articles of Examples 14 to 16 were compared with those of Comparative Examples 10 to 15, all of them contained a copolymer of propylene and ethylene as a base resin. In the polypropylene resin foam molded articles of Comparative Examples 10 to 15, the relationship between the moisture permeability Y (g / m ² / hr) and the density X (g / cm ³ ) does not satisfy the relationship of the above formula (2). . And when Examples 14-16 and Comparative Examples 10-15 are respectively compared with those having substantially the same molding conditions, the polypropylene resin foam molded bodies of Examples 14-16 are excellent in heat resistance and strength, Compared to Comparative Examples 10 to 15, the moisture permeability was small and the moisture resistance was excellent.

Moreover, when the polypropylene resin foam molded articles of Examples 17 to 19 were compared with those of Comparative Examples 16 to 18, they all contained a copolymer of propylene and 1-butene as a base resin. However, in the polypropylene resin foam molded articles of Comparative Examples 16 to 18, the relationship between the moisture permeability Y (g / m ² / hr) and the density X (g / cm ³ ) satisfies the relationship of the above formula (2). Not. And when Examples 17-19 and Comparative Examples 16-18 are respectively compared with those having substantially the same molding conditions, the polypropylene resin foam molded bodies of Examples 17-19 are excellent in heat resistance and strength, Compared with Comparative Examples 16 to 18, the moisture permeability was small and the moisture resistance was excellent.

Explanatory drawing which shows the stress-strain diagram of the polypropylene resin foaming molding concerning Example 6. FIG.

Claims (5)

A polypropylene resin foam molded article obtained by thermoforming foamed particles obtained using a metallocene polymerization catalyst and having a propylene polymer having the following requirements (a) and (b) as a base resin,
The polypropylene resin foamed molded product has the following requirement (c):
(A) The structural unit obtained from propylene is 100 to 85 mol%, and the structural unit obtained from ethylene and / or an α-olefin having 4 to 20 carbon atoms is present in an amount of 0 to 15 mol% (provided from propylene) The total amount of structural units and structural units obtained from ethylene and / or α-olefin having 4 to 20 carbon atoms is 100 mol%).
(B) The proportion of position irregular units based on 2,1-insertion of propylene monomer units in all propylene insertions measured by ¹³ C- NMR is 0.5 to 2.0%, and propylene monomer units The proportion of irregular units based on 1,3-insertion is 0.08 to 0.4%.
(C) The density X of the polypropylene resin foam molded article is 0.008 to 0.052 g / cm ³ , and the moisture permeability Y [g / m ² / hr] measured in accordance with ASTM E-96; The density X [g / cm ³ ] of the polypropylene resin foamed molded article satisfies the following formula (2).
Y <= (43.6) * X < ² >-(4.5) * X + 0.15 Formula (2) 2. The polypropylene resin foam molded article according to claim 1, wherein the propylene polymer is obtained using the metallocene polymerization catalyst having a hydroazurenyl group as a ligand . 3. The polypropylene resin foam molded article according to claim 1, wherein the propylene polymer further has the following requirement (e) .
(E) The isotactic triad fraction measured by ¹³ C-NMR of the propylene unit chain part consisting of a head-to-tail bond is 97% or more. The polypropylene resin foam molded article according to any one of claims 1 to 3, wherein the propylene polymer further has the following requirement (f) .
(F) The melt flow rate is 0.5 to 100 g / 10 minutes. The polypropylene resin foam molded article according to any one of claims 1 to 4, wherein the density of the polypropylene resin foam molded article is 0.01 to 0.045 g / cm ³ .

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