JP2017179070A - Manufacturing method of modified polypropylene resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a modified polypropylene resin exhibiting high melting tensile force, excellent in flowability and less in content of a gel.SOLUTION: There is provided a manufacturing method of a modified polypropylene resin for manufacturing the modified polypropylene resin having higher melting tensile force than a polypropylene resin by reacting the polypropylene resin and an aromatic vinyl monomer, a mixture containing 2 kinds of polypropylene resin having different MFR, an aromatic vinyl monomer and organic peroxide and reacting the aromatic vinyl monomer and the polypropylene resin.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a modified polypropylene resin.

Conventionally, polypropylene resins have been used as raw materials for various molded articles because of their excellent mechanical properties and chemical resistance.
As a molded product made of polypropylene resin, a foam molded product obtained by thermoforming a polypropylene resin foam sheet is known.
As this polypropylene resin foam sheet, one having a single foam layer or one having a laminated structure in which a foam layer and a non-foam layer are laminated is known.
In distinguishing these, the term “foamed sheet” is used in the narrow sense and used in the former sense, and the latter is called “laminated foamed sheet” or the like.
These foam sheets and laminated foam sheets are conventionally produced by extrusion foaming, but polypropylene resins generally have crystallinity, so the viscosity and melt tension at the time of melting tend to be insufficient, and the foamed state is good. It is difficult to get things.

In order to solve such problems, it has been studied to adjust the melting characteristics by modifying a polypropylene resin with an aromatic vinyl monomer such as a styrene monomer.
For example, Patent Document 1 listed below describes a method for obtaining a modified polypropylene resin having a property that the elongational viscosity measured in a molten state rapidly increases as the amount of strain increases (also referred to as “strain hardening”). Has been.

JP 09-188728 A

As a method for obtaining a modified polypropylene resin, it is known that a monomer is reacted with a polypropylene resin as a raw material to produce a modified polypropylene resin having a higher melt tension than the polypropylene resin. In addition, the lower the melt mass flow rate of the polypropylene resin, the more advantageous it is in giving a high melt tension to the modified polypropylene resin.
However, the modified polypropylene resin as described above exhibits a high melt tension at the time of heat melting, but may not exhibit sufficient fluidity.
In addition, a polypropylene resin having a high melt mass flow rate value increases the amount of monomer used to give a high melt tension to the modified polypropylene resin, and as a result, a large amount of gel is contained in the modified polypropylene resin. There is a possibility that.
Accordingly, an object of the present invention is to provide a modified polypropylene resin having a low gel content.

  In order to solve the above-mentioned problems, the present invention provides a method for producing a modified polypropylene resin in which an aromatic vinyl monomer is reacted with a polypropylene resin to produce a modified polypropylene resin having a higher melt tension than the polypropylene resin. A first polypropylene resin exhibiting a melt mass flow rate of 4.0 g / 10 min or more under measurement conditions of a temperature of 230 ° C. and a nominal load of 2.16 kg, and a second polypropylene having the melt mass flow rate of less than 4.0 g / 10 min Provided is a method for producing a modified polypropylene resin in which an admixture containing an epoxy resin, an aromatic vinyl monomer, and an organic peroxide is melt-kneaded to react the aromatic vinyl monomer with the polypropylene resin. .

  According to the present invention, it is possible to provide a modified polypropylene resin that exhibits high melt tension, is excellent in fluidity, and has a low gel content.

The schematic sectional drawing of the polypropylene resin foam sheet of one Embodiment. Schematic showing the equipment structure for manufacturing the polypropylene resin laminated foam sheet. FIG. 3 is a detailed view of a broken line A portion in FIG. 2. The schematic perspective view which showed the instruments for measuring a gel fraction.

Embodiments of the present invention will be described.
Hereinafter, a case where a polypropylene resin foam sheet having a laminated structure is produced using a modified polypropylene resin obtained by reacting a polypropylene resin and an aromatic vinyl monomer will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of a polypropylene resin foam sheet. As shown in the figure, the polypropylene resin foam sheet of this embodiment includes a foam layer 10 and non-foam layers 20, 20 ′. Yes.
In the following, a polypropylene resin foam sheet having one or more foamed layers and one or more non-foamed layers including the one shown in FIG. 1 and a polypropylene system having two or more foamed layers are included. The resin foam sheet is referred to as a “laminated foam sheet” and is distinguished from a polypropylene resin foam sheet having a single foam layer.
Therefore, in the following, unless otherwise specified, the term “laminated foam sheet” means that having a laminated structure as shown in FIG. 1, and the term “foam sheet” means a single foam layer. It is used as a term to mean the sheet.

As described above, the laminated foam sheet 1 of this embodiment includes the foam layer 10 and the non-foam layers 20 and 20 ′.
The foam layer 10 of the present embodiment is formed by a foam sheet produced by an extrusion foaming method.
The non-foamed layers 20 and 20 ′ are formed of a resin film produced by an extrusion method.
The laminated foam sheet 1 of this embodiment is a co-extruded product of the foam layer 10 and the non-foam layers 20 and 20 ′.
That is, in the laminated foamed sheet 1 of the present embodiment, a polypropylene resin composition for producing an extruded foamed sheet and an extruded film is laminated in a confluence mold, and these are laminated and integrated from one die slit. Extruded in a state.

In the laminated foam sheet 1 of the present embodiment, the foam layer 10 and the non-foam layers 20 and 20 ′ are formed of a polypropylene resin composition containing a modified polypropylene resin.
Of the polypropylene resin compositions that form the foam layer 10 and the non-foam layers 20, 20 ', the first polypropylene resin composition that forms the foam layer 10 includes a modified polypropylene resin, and is further expanded. Contains ingredients for.
The second polypropylene resin composition that forms the non-foamed layers 20 and 20 'also contains a modified polypropylene resin.
The first polypropylene resin composition that forms the foamed layer 10 and the second polypropylene resin composition that forms the non-foamed layers 20 and 20 'are different even if they contain the same modified polypropylene resin. May be.

The modified polypropylene resin of this embodiment is produced by a specific modified polymer manufacturing method.
First, the modified polypropylene resin and the production method thereof will be described.

(Modified polypropylene resin)
The modified polypropylene resin of the present embodiment is a resin composition containing (A) a polypropylene resin, (B) an organic peroxide, and (C) an aromatic vinyl monomer (hereinafter also referred to as “raw material composition”). It was obtained by reacting.
As the modified polypropylene-based resin of the present embodiment, it is preferable to employ a resin whose phase angle obtained by frequency dispersion dynamic viscoelasticity measurement at 200 ° C. is 30 ° or more and 70 ° or less at a frequency of 0.01 Hz.
In frequency dispersion dynamic viscoelasticity measurement, the influence of the viscosity term tends to appear in the low frequency region.
That is, the modified polypropylene resin of the present embodiment has a small phase angle in the low frequency region and is less likely to cause “slip” between molecules.
Therefore, the modified polypropylene resin of the present embodiment exhibits a moderate elongation when foamed to form a foamed layer, and it is possible to suppress the bubble film from becoming rapidly thinner as the bubble grows. Therefore, film breakage (bubble breakage) is prevented, which is advantageous for obtaining a foam sheet having a low open cell ratio.
Furthermore, the modified polypropylene resin of the present embodiment causes a phenomenon of “resin cut” (hereinafter referred to as “resin cut”) such as tearing and hole opening due to stretching in the non-foamed layer, and the foamed layer is exposed on the surface of the non-foamed layer. It is advantageous for suppressing the draw-down at the time of being extrude | pushed out and forming in the state integrated | stacked and integrated from the die slit.

The phase angle is obtained as follows.
(How to find the phase angle)
The dynamic viscoelasticity measurement is performed with a viscoelasticity measuring device PHYSICA MCR301 (manufactured by Anton Paar) and a temperature control system CTD450.
First, the modified polypropylene resin used as a sample is pressed under a condition of heating at a temperature of 200 ° C. for 5 minutes with a hot press machine to produce a disk sample having a diameter of 25 mm and a thickness of 3 mm.
Next, the sample is set on a plate of a viscoelasticity measuring apparatus heated to a measurement temperature (200 ° C.), and heated and melted for 5 minutes in a nitrogen atmosphere.
Thereafter, the interval is crushed to 2.0 mm with a parallel plate having a diameter of 25 mm, and the resin protruding from the plate is removed.
Further, after heating for 5 minutes after reaching the measurement temperature ± 1 ° C, the condition is 5% strain, frequency 0.01 to 100 (Hz), the number of measurement points is 21 (5 points / digit), and the measurement temperature is 200 ° C. Then, dynamic viscoelasticity measurement is performed to measure the phase angle δ (°).
Measurement starts from the high frequency side (100 Hz).
Then, the phase angle δ at a frequency of 0.01 Hz is obtained.

  In order to more reliably exert the effects of reducing the open cell ratio of the foam layer 10 and suppressing the resin breakage of the non-foam layers 20 and 20 ', the modified polypropylene resin not only exhibits the above phase angle. In addition, at least one of the first polypropylene resin composition and the second polypropylene resin composition, preferably both, exhibit a phase angle of 30 ° to 70 ° at a temperature of 200 ° C. and a frequency of 0.01 Hz. preferable.

The modified polypropylene resin contained in the first polypropylene resin composition and the second polypropylene resin composition is modified so as to exhibit a higher melt tension than the starting material (A) polypropylene resin. It is.
Whether or not the modified polypropylene resin exhibits a higher melt tension than the polypropylene resin used as a raw material can be determined by comparing the melt tension at a temperature of 230 ° C., for example.
Since a general polypropylene resin has a melt tension of less than a few cN at 230 ° C., the melt tension measured at 230 ° C. is not less than 6 cN, as compared with the starting material (A) polypropylene resin. Those showing values can be regarded as modified polypropylene resins.

The modified polypropylene resin preferably has a melt tension at 230 ° C. of 6 cN or more, more preferably a melt tension at 230 ° C. of 10 cN or more, and a melt tension at 230 ° C. of 15 cN or more. Is particularly preferred.
However, if the melt tension of the modified polypropylene resin is excessively high, the load on the extruder may be increased when the first polypropylene resin composition or the second polypropylene resin composition is extruded. Therefore, the value at 230 ° C. is preferably 30 cN or less, and more preferably 28 cN or less.

In addition, when calculating | requiring melt tension regarding a modified polypropylene resin, a laminated foam sheet, etc., it can obtain | require by the following methods.
[Measuring method of melt tension]
The sample is used as it is when the object to be measured is pellets, and in the case of a sheet such as a laminated foam sheet, the sheet is used as a pelletizer (for example, “Hand Truda Model PM-1” manufactured by Toyo Seiki Seisakusho Co., Ltd.) Then, pellets are used under the conditions of a cylinder temperature of 220 ° C. and a waiting time of 2.5 minutes from sample filling to extrusion start.
The melt tension is measured using a twin-bore capillary rheometer Rheological 5000T (manufactured by Chiast, Italy).
That is, after filling the measurement sample resin in a 15 mm diameter barrel heated to the test temperature and preheating for 5 minutes, the piston descending speed from the capillary die (diameter 2.0 mm, length 20 mm, inflow angle flat) of the above measuring device While holding (0.1546 mm / s) constant and extruding into a string, the string was passed through a tension detection pulley located 27 cm below the capillary die, and then using a winding roll, The winding speed is gradually increased at an initial speed of 8.7 mm / s and an acceleration of 12 mm / s ² , and the average of the maximum value and the minimum value immediately before the string-like material is cut is defined as the melt tension of the sample. .
When there is only one maximum point on the tension chart, the maximum value is taken as the melt tension.

The modified polypropylene-based resin is melted in order to reduce the load on the extruder during extrusion, to exhibit good foamability in the foamed layer 10, and to prevent the non-foamed layers 20 and 20 'from being out of resin. It is preferable that a mass flow rate (MFR) shows a predetermined value.
More specifically, the modified polypropylene resin preferably has an MFR of 0.5 g / 10 min or more, more preferably 0.7 g / 10 min or more, and particularly preferably 1.0 g / 10 min or more. preferable.
In forming a foamed layer having excellent closed cell properties (low open cell rate), the MFR of the modified polypropylene resin is preferably 0.7 g / 10 min or more.
However, if the MFR is excessively high, it may be difficult to cause the foamed layer 10 to exhibit good foamability. Therefore, the MFR of the modified polypropylene resin is preferably 5.0 g / 10 min or less. More preferably, it is 0 g / 10 min or less.
The MFR of the modified polypropylene resin can be measured based on the method B of JIS K7210: 1999 “Plastic-thermoplastic plastic melt mass flow rate (MFR) and melt volume flow rate (MVR) test methods”. It can be measured at a temperature of 230 ° C. and a nominal load of 2.16 kg.
More specifically, MFR is measured as follows.
When the measurement object is a pellet, it is used as it is as a measurement sample.
When the measurement object is a foamed sheet, the foamed sheet is pelletized using a pelletizer “Hand Truda Model PM-1” manufactured by Toyo Seiki Seisakusho Co., Ltd. as a measurement sample.
In addition, the cylinder temperature at the time of producing a pellet from a foam sheet using a pelletizer shall be 220 degreeC, and the waiting time from a sample filling to the start of extrusion shall be 2.5 minutes.
The melt mass flow rate (MFR) is a semi-auto melt indexer 2A manufactured by Toyo Seiki Seisakusho Co., Ltd. Method Measured by “b) Method of measuring time for piston to move a predetermined distance” described in method B.
The measurement conditions are a sample amount of 3 to 8 g, a preheating time of 270 seconds, a load hold time of 30 seconds, a test temperature of 230 ° C., a test load of 21.18 N, and a piston moving distance (interval) of 4 mm.
The number of tests is 3 times, and the average value is the value of melt mass flow rate (g / 10 min).

  In obtaining such a modified polypropylene resin, the starting material (A) polypropylene resin preferably has a predetermined melting property.

[(A) Polypropylene resin]
(A) Polypropylene resin is a polymer obtained by polymerizing a propylene monomer.
Examples of the (A) polypropylene resin to be contained in the raw material composition for obtaining the modified polypropylene resin include a homopolymer of a propylene monomer and a copolymer of a propylene monomer and another monomer.
In the copolymer, for example, in 100% by mass of the polymerization component, the content of propylene monomer is preferably 50% by mass or more, and the content of propylene monomer is more preferably 80% by mass or more. The content of is particularly preferably 90% by mass or more.
The copolymerization may be random copolymerization or block copolymerization.
When the polypropylene resin is a copolymer, the component other than the propylene monomer is preferably at least one selected from the group consisting of an ethylene monomer and an α-olefin monomer having 4 to 8 carbon atoms. -More preferably, it is at least one of butene monomers.

Specific examples of (A) polypropylene resins include propylene homopolymers, propylene random polymers, and propylene block polymers.
(A) The polypropylene resin is preferably a homopolymer of a propylene monomer, and is preferably a propylene homopolymer.

In order for the modified polypropylene resin to exhibit a high MFR value, it is preferable to employ (A) a polypropylene resin that exhibits a high MFR.
Polypropylene resin used as a general foam sheet forming material has an MFR of about 1 g / 10 min or less, but as a polypropylene resin as a starting material for the modified polypropylene resin, melt mass flow rate (MFR) is 4 It is preferable that it is 0.0 g / 10 min or more.
(A) The MFR of the polypropylene resin is more preferably 4.0 g / 10 min or more and 20.0 g / 10 min or less, and particularly preferably 7.0 g / 10 min or more and 18.0 g / 10 min or less.

(A) In general, the lower the value of the melt mass flow rate of the polypropylene-based resin, the more advantageous in giving a high melt tension to the modified polypropylene-based resin.
Therefore, when only the high MFR (A) polypropylene resin is used as the starting material for the modified polypropylene resin as described above, in order to give a high melt tension to the modified polypropylene resin, (C) As a result of increasing the amount of the aromatic vinyl monomer used, a large amount of gel may be included in the modified polypropylene resin.
Therefore, as a starting material for the modified polypropylene resin, the first polypropylene resin showing an MFR of 4.0 g / 10 min or more and the second polypropylene resin having an MFR of less than 4.0 g / 10 min are used in combination. It is preferable.

  The first polypropylene resin is preferably selected from those showing an MFR of 4.0 g / 10 min or more and 20 g / 10 min or less, although it shows an MFR of 7.0 g / 10 min or more and 18.0 g / 10 min or less. More preferably, it is selected from among them.

  The second polypropylene resin having an MFR lower than that of the first polypropylene resin is preferably selected from those showing an MFR of 0.1 g / 10 min to 4.0 g / 10 min, More preferably, it is selected from those showing an MFR of 10 min or more and 4.0 g / 10 min or less.

For example, the first polypropylene resin and the second polypropylene resin can be blended so that the mass ratio (first PP / second PP) is 90/10 to 10/90.
As described above, when a plurality of polypropylene resins are used as starting materials for the modified polypropylene resins, the mixed resin in which all the polypropylene resins contained in the starting materials are mixed at a ratio of the starting materials has an MFR of 4.0 g / 10 min. The above is preferable.

In the raw material composition, the mass percentage of the first polypropylene resin in the total value of the mass of the first polypropylene resin and the mass of the second polypropylene resin is a ₁ (%), and the second polypropylene resin the mass percentage as _a 2 (%), the value of the melt mass flow rate of the first polypropylene resin _a 1 (g / 10min), the value of the melt mass flow rate of the second polypropylene resin _a 2 (g / 10 min), it is preferable that at least the following relational expression (x) is satisfied.

[A ₁ × a ₁ + A ₂ × a ₂ ] / 100> 4.0 (x)

By obtaining the above-described relationship between the first polypropylene resin and the second polypropylene resin in the raw material composition, it is possible to obtain a modified polypropylene resin for obtaining an extruded laminated foam sheet having a low air-fuel ratio. There is an effect that can be done.

  The MFR of the polypropylene resin (A), which is the starting material of the modified polypropylene resin, is JIS K7210: 1999 “Plastic-thermoplastic melt mass flow rate (MFR) and melt, similarly to the MFR of the modified polypropylene resin. Based on Method B of “Volume Flow Rate (MVR) Test Method”, measurement can be performed under conditions of a temperature of 230 ° C. and a nominal load of 2.16 kg.

The gel contained in the modified polypropylene resin may cause coarse bubbles to be formed in the foamed layer, or cause the resin to run out or to form minute protrusions called “bumps” in the non-foamed layer.
However, the modified polypropylene resin of the present embodiment uses a plurality of polypropylene resins having different MFRs as a starting material as described above, so that the gel fraction value is, for example, 1.0% by mass or less. Preferably, the value of the gel fraction can be 0.6% by mass or less, particularly preferably 0.3% by mass or less.

In addition, when calculating | requiring gel content (gel fraction) about a modified polypropylene resin and a laminated foam sheet, it can obtain | require by the following methods using an instrument as shown in FIG.
[Method for measuring gel content]
For the sample, pellets and beads are used as they are, and the foam is cut to about 1 cm square.
After precisely weighing 0.8 g of the sample, it is put in a 200 mesh wire net having a flat bottom and folds on the side.
Into a 200 mL tall beaker (symbol TB in FIG. 4), a slat (symbol BM in FIG. 4) is placed.
A mesh wire net containing a sample is placed on the slat and 80 ml of xylene is added.
After stirring for 3 hours at 130 ° C. and 80 rpm using a heating and agitation driver apparatus (As One HDBS-6), the 200-mesh wire mesh in the tall beaker was taken out with tweezers and washed in 80 mL of xylene heated to 130 ° C. Remove deposits on the side of the wire mesh.
Thereafter, the resin insoluble matter on the wire mesh is naturally dried in a draft to evaporate xylene, and finally the resin insoluble matter is dried together with the wire mesh at 120 ° C. for 2 hours in a constant temperature dryer.
After cooling in a desiccator, the mass of the entire wire mesh was measured, and the gel content (% by mass) was calculated by the following formula.

Gel content (mass%) = insoluble resin mass (g) on wire mesh / sample mass (0.8 g) × 100

(Insoluble resin mass on wire mesh = wire mesh mass after filtration and drying-mass only for wire mesh before filtration)

The amount of gel contained in the modified polypropylene resin is not limited to using a plurality of polypropylene resins having different MFR as a starting material, but also a monomer that reacts with the starting material and a radical that reacts the monomer with the polypropylene resin. It can also be reduced by selecting the type of generator and limiting the amount.
In this embodiment, an organic peroxide is used as the radical generator, and an aromatic vinyl monomer is used as the monomer.

[(B) Organic peroxide]
The (B) organic peroxide of this embodiment has a hydrogen abstraction ability with respect to a polypropylene resin, and is not particularly limited. For example, hydroperoxide, dialkyl peroxide, peroxyester, diacyl peroxide, peroxide Examples thereof include oxydicarbonate, peroxyketal, and ketone peroxide.

Examples of the hydroperoxide include permethane hydroperoxide, diisopropylbenzene hydroperoxide, cumene hydroperoxide, and t-butyl hydroperoxide.
Examples of the dialkyl peroxide include dicumyl peroxide, di-t-butyl peroxide, and 2,5-dimethyl-2,5-di (t-butylperoxy) -hexyne-3. .
Examples of the peroxyester include t-butyl peroxy 2-ethylhexyl carbonate, t-hexyl peroxyisopropyl monocarbonate, t-hexyl peroxybenzoate, t-butyl peroxybenzoate, t-butyl peroxylaurate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxyacetate, 2,5-dimethyl2,5-di (benzoylperoxy) hexane, and t-butylperoxyisopropyl monocarbonate Etc.
Examples of the diacyl peroxide include dibenzoyl peroxide, di (4-methylbenzoyl) peroxide, and di (3-methylbenzoyl) peroxide.
Examples of the peroxydicarbonate include di (2-ethylhexyl) peroxydicarbonate and diisopropyl peroxydicarbonate.
Examples of the peroxyketal include 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-t-butylperoxycyclohexane, 2,2-di (t -Butylperoxy) -butane, n-butyl 4,4-di- (t-butylperoxy) valerate, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane and the like It is done.
Examples of the ketone peroxide include methyl ethyl ketone peroxide and acetylacetone peroxide.

The organic peroxide (B) in this embodiment is preferably a peroxyester, diacyl peroxide, or peroxydicarbonate.
The organic peroxide preferably has a structure represented by the following general formula (X).

（但し、Ｒ^１は、置換若しくは非置換のフェニル基又は置換若しくは非置換のアルコキシ基を表し、Ｒ^２は１価の有機基を表している。）

(However, R ¹ represents a substituted or unsubstituted phenyl group or a substituted or unsubstituted alkoxy group, and R ² represents a monovalent organic group.)

In the general formula (X), when “R ¹ ” is an alkoxy group, “R ¹ ” is an alkyl group having a branched structure having 3 to 8 carbon atoms (for example, isopropyl, t-butyl). , T-hexyl, 2-ethylhexyl, etc.) are preferably alkoxy groups having an oxygen atom bonded thereto.
When “R ¹ ” is other than an alkoxy group in which an oxygen atom is bonded to 2-ethylhexyl, the oxygen atom is preferably bonded to a secondary carbon or a tertiary carbon, and is represented by the following general formula (Y) It preferably has a structure.

（但し、式中の「Ｒ^１１」、「Ｒ^１２」は、何れか一方がメチル基で他方が水素原子で、「Ｒ^１４」が炭素数１〜６の直鎖アルキル基を表し、「Ｒ^１３」が２級炭素か３級炭素であることを表している。）

(However, “R ¹¹ ” and “R ¹² ” in the formulas represent either a methyl group, the other is a hydrogen atom, and “R ¹⁴ ” represents a straight-chain alkyl group having 1 to 6 carbon atoms; ¹³ "represents secondary carbon or tertiary carbon.)

When “R ¹ ” is either a substituted or unsubstituted phenyl group, “R ¹ ” is an unsubstituted phenyl group or a substituted phenyl in which one hydrogen atom is substituted with a methyl group It is preferable that

“R ² ” also preferably has a bulky structure such as branched alkyl or phenyl.
Specifically, it preferably has a structure represented by the following general formula (Z).

（但し、式中の「Ｒ^２１」は、炭素数１〜６の直鎖アルキル基か、又は、フェニル基を有する１価の有機基かの何れかであることを表している。）

(However, “R ²¹ ” in the formula represents either a linear alkyl group having 1 to 6 carbon atoms or a monovalent organic group having a phenyl group.)

  Examples of the organic peroxide having the structure represented by the general formula (X) include t-butyl peroxy 2-ethylhexyl carbonate, t-hexyl peroxyisopropyl monocarbonate, t-butyl peroxyisopropyl monocarbonate, t -Hexylperoxybenzoate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, dibenzoyl peroxide, di (4-methylbenzoyl) peroxide, diisopropylperoxydicarbonate, etc. .

In the raw material composition for producing the modified polypropylene resin, the content of the organic peroxide (B) relative to 100 parts by mass of the (A) polypropylene resin is 0.1 parts by mass or more and 1.5 parts by mass or less. Preferably there is.
In the modified polypropylene resin of the present embodiment, when the content of (B) organic peroxide is too small, the reactivity of the raw material composition becomes low, so that a good modifying effect may not be exhibited.
In the modified polypropylene resin of this embodiment, if the content of (B) organic peroxide is excessive, the decomposition reaction of the polypropylene resin is likely to occur during melt-kneading, so the elastic component becomes small and good modification is achieved. The effect may not be demonstrated.
That is, when the content of the organic peroxide (B) is 0.1 parts by mass or more and 1.5 parts by mass or less, the raw material composition does not control the reaction conditions during melt-kneading with high accuracy. In addition, a modified polypropylene resin having excellent melt tension can be produced.

  In the raw material composition, in order to more reliably produce a modified polypropylene resin having excellent melt tension, the content of (B) organic peroxide with respect to 100 parts by mass of (A) polypropylene resin is 0.3. The amount is preferably at least part by mass, and preferably at most 1.0 part by mass.

[(C) aromatic vinyl monomer]
The (C) aromatic vinyl monomer is a component that acts as a crosslinking agent that chemically bonds to the (A) polypropylene resin to form a branched structure and to crosslink the polypropylene resins.
The (C) aromatic vinyl monomer to be contained in the raw material composition may be one type or two or more types.
Examples of the aromatic vinyl monomer include styrene; methyl styrene such as o-methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl styrene, β-methyl styrene, dimethyl styrene, and trimethyl styrene; α-chlorostyrene. , Β-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, dichlorostyrene, trichlorostyrene, etc .; o-bromostyrene, m-bromostyrene, p-bromostyrene, dibromostyrene, tri Bromostyrene such as bromostyrene; fluorostyrene such as o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, difluorostyrene, trifluorostyrene; o-nitrostyrene, m-nitrostyrene, p-nitros Nitrostyrene such as len, dinitrostyrene and trinitrostyrene; vinylphenol such as o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, dihydroxystyrene and trihydroxystyrene; o-divinylbenzene, m-divinylbenzene, p -Divinylbenzene such as divinylbenzene; and isopropenylbenzene such as o-diisopropenylbenzene, m-diisopropenylbenzene, p-diisopropenylbenzene.
Among these, the aromatic vinyl monomer is preferably styrene.

The content of the aromatic vinyl monomer (C) in the raw material composition is preferably 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the (A) polypropylene resin.
When the content of the aromatic vinyl monomer (C) is too small, the modified polypropylene resin does not sufficiently form a branched or crosslinked structure in melt-kneading, and the decomposition suppression of the resin by peroxide is insufficient. Therefore, there is a possibility that a good reforming effect cannot be exhibited.
If the content of the (C) aromatic vinyl monomer is excessive, the modified polypropylene resin can easily become unreacted by (C) the aromatic vinyl monomer by melt kneading. As a result, there is a possibility that the elastic component becomes large and noisy becomes bad and a good reforming effect cannot be obtained.
That is, the content of the aromatic vinyl monomer (C) is 0.1 parts by mass or more and 10 parts by mass or less, so that the raw material composition is open-celled without controlling the reaction conditions during melt-kneading with high accuracy A modified polypropylene resin capable of obtaining a laminated foam sheet having a foam layer having a low rate can be produced.

If necessary, the raw material composition may contain a monomer other than the aromatic vinyl monomer.
Examples of the monomer include ethylene, 1-butene, isobutene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3,4-dimethyl-1-butene, 1 Α-olefin monomers such as heptene, 3-methyl-1-hexene, 1-octene and 1-decene; cycloolefin monomers such as cyclopentene and norbornene; 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, Diene monomers such as 1,4-hexadiene, methyl-1,4-hexadiene, 7-methyl-1,6-octadiene; chlorine-based monomers such as vinyl chloride and vinylidene chloride; acrylonitrile, acrylic acid, methacrylic acid, maleic acid, Ethyl acrylate, butyl acrylate, glycidyl acrylate, methacrylate Epoxy monomers; methyl, glycidyl methacrylate, acrylic monomers such as maleic anhydride acetate based monomers such as vinyl acetate and the like.

[(D) Radical scavenger]
In order to obtain the modified polypropylene resin, the raw material composition preferably contains (D) a radical scavenger to control the reactivity.
(D) Use of the radical scavenger is effective for increasing the melt tension of the modified polypropylene resin.
That is, the radical scavenger (D) is effective in obtaining a resin foam having a good appearance using a modified polypropylene resin.

(D) The radical scavenger is capable of reacting with alkyl radical species.
(D) It is preferable that the radical scavenger can be bonded to the aromatic vinyl monomer after being bonded to the alkyl radical.
(D) As for a radical scavenger, only 1 type may be used and 2 or more types may be used together.

  Examples of the radical scavenger (D) include quinone compounds (quinones), naphthoquinone compounds (naphthoquinones), and phenothiazine compounds (phenothiazines).

Examples of the quinone compound include p-benzoquinone, p-naphthoquinone, 2-t-butyl-p-benzoquinone, and 2,5-diphenyl-p-benzoquinone. Examples of the naphthoquinone compound include 1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, vitamin K, and the like.
Examples of the phenothiazine compound include phenothiazine, bis- (α-methylbenzyl) phenothiazine, 3,7-dioctylphenothiazine, and bis- (α-dimethylbenzyl) phenothiazine.

In the raw material composition, the content of the (D) radical scavenger with respect to 100 parts by mass of the (A) polypropylene resin is preferably 0.005 parts by mass or more, more preferably 0.05 parts by mass or more.
Further, the content of the (D) radical scavenger with respect to 100 parts by mass of (A) polypropylene resin is preferably 1 part by mass or less.
(D) When the content of the radical scavenger is not less than the lower limit and not more than the upper limit, the melt tension of the modified polypropylene resin is effectively increased, and the appearance of the foam is further improved.

  In addition to these, (E) Other components to be contained in the raw material composition include various additives.

[(E) Additive]
(E) An additive is suitably used according to various objectives, and is not specifically limited.
(E) Specific examples of the additive include a weather resistance stabilizer, an antistatic agent, an antioxidant, a deodorant, a light stabilizer, a crystal nucleating agent, a pigment, a lubricant, imparting slipperiness or anti-blocking property. Examples thereof include a surfactant for the purpose of imparting, an inorganic filler, and a dispersibility improver for improving the dispersibility of the inorganic filler.
Examples of the dispersibility improver include higher fatty acids, higher fatty acid esters, and higher fatty acid amides.

The (E) additive may be contained in the raw material composition before melt-kneading or at the time of melt-kneading.
In addition, the additive (E) may be added after melt-kneading and contained in the modified polypropylene resin.
(E) As for an additive, only 1 type may be used and 2 or more types may be used together.

  In the modified polypropylene resin according to this embodiment, the organic peroxide is contained in an amount of 0.1 to 1.5 parts by mass with respect to 100 parts by mass of the polypropylene resin, and the aromatic vinyl monomer However, it can be easily obtained by melt-kneading a raw material composition containing 0.1 to 10 parts by mass of the aromatic vinyl monomer with respect to 100 parts by mass of the polypropylene resin.

The modified polypropylene resin according to the present embodiment is suitable for forming a foam molded article having a good appearance and excellent strength.
When the modified polypropylene resin according to the present embodiment is foamed, it is difficult for foam breakage to occur inside, and it is possible to obtain a foamed molded article having a good appearance with a low open cell ratio.
Moreover, the modified polypropylene resin according to the present embodiment has an advantage that a foamed sheet having a low open cell ratio is easily obtained.
Furthermore, the modified polypropylene resin according to the present embodiment has a low gel fraction and exhibits good flowability, and is suitable not only for forming a foam layer but also for forming a non-foam layer.

(Method for producing modified polypropylene resin)
In the production of the modified polypropylene resin, for example, (A) 100 parts by mass of polypropylene resin, (B) 0.1 to 1.5 parts by mass of organic peroxide, and (C) aromatic vinyl A method of obtaining a modified polypropylene resin by melting and kneading a raw material composition containing 0.1 to 10 parts by mass of a monomer can be employed.
At the time of melt kneading the raw material composition, it is preferable to control the heating temperature in order to bring the raw material composition into a good molten state.
The raw material composition reacts by heating during melt kneading.
That is, the organic peroxide generates a radical by the heating, and the radical attacks the hydrogen bonded to the tertiary carbon of the polypropylene resin to form an alkyl radical.
In this state, β-cleavage occurs and molecular cleavage of the polypropylene resin occurs, but in this embodiment, the aromatic vinyl monomer is bonded to the site to form a branched structure (crosslinked structure).

(C) The aromatic vinyl monomer is obtained by mixing (A) a polypropylene resin and (B) an organic peroxide from the viewpoint of making the addition effect remarkable, and then obtaining the mixture. It is preferable to add to.
However, (A) polypropylene resin, (B) organic peroxide, and (C) aromatic vinyl monomer may be mixed together.
(D) The radical scavenger may be added before (C) the aromatic vinyl monomer is added, or may be added after (C) the aromatic vinyl monomer is added, and mixed together with other components. May be.
(E) The additive may be added before adding the (C) aromatic vinyl monomer, or may be added after adding the (C) aromatic vinyl monomer, and is mixed together with other components. May be.

In addition, melt kneading | mixing of a raw material composition can be implemented using general apparatuses, such as a kneader, a Banbury mixer, and an extruder.
When melt-kneading the raw material composition, it is preferable to use an extruder.
Preferably, the raw material composition is supplied to an extruder and subjected to a crosslinking reaction in the extruder to form a modified polypropylene resin, and the modified polypropylene resin is extruded from the extruder.
A modified polypropylene resin is efficiently obtained by continuously supplying the raw material composition to an extruder and continuously extruding the modified polypropylene resin from the extruder.

Examples of the extruder include a single screw extruder and a twin screw extruder.
The said extruder can be used for manufacture of a modified polypropylene resin as a single or a tandem-type extruder connected in plural.
In particular, a twin screw extruder is preferable from the viewpoint of further increasing dispersibility and reactivity of other components with respect to the polypropylene resin as the base resin.

In this method for producing a modified polypropylene resin, carbon dioxide is supplied to an extruder, carbon dioxide is added to the kneaded material melt-kneaded, and the kneaded material added with carbon dioxide is further melt-kneaded for a certain period of time. It is preferable to discharge the gas containing carbon from the kneaded product.
That is, in the method for producing a modified polypropylene resin, a reaction step of reacting a polymer and a monomer by melt kneading, and a carbon dioxide addition step of adding carbon dioxide to a kneaded product obtained by melt kneading in the reaction step It is preferable to carry out a degassing step of discharging a gas containing carbon dioxide from the kneaded material to which carbon dioxide has been added.

When the reaction step is carried out with an extruder, the carbon dioxide addition step is preferably carried out with the same extruder as the reaction step or another extruder connected to the extruder.
That is, in the former case, for example, a carbon dioxide supply point is provided near the exit of the extruder, and (A) a polypropylene resin, (B) an organic peroxide, (C) upstream of the carbon dioxide supply point. ) It can be carried out using an extruder provided with a material supply point for a raw material composition such as an aromatic vinyl monomer.
In the latter case, a tandem extruder in which an upstream extruder and a downstream extruder are connected is used, a polypropylene resin is reformed in the upstream extruder, and carbon dioxide is added in the downstream extruder. And further melt kneading.

The degassing step may be performed simply by discharging the kneaded material from an extruder, and using an extruder provided with a vent mechanism, carbon dioxide is discharged from the kneaded material before discharging the kneaded material by the vent mechanism. You may make it discharge.
By performing the carbon dioxide addition step and the degassing step, the remaining monomer without being consumed in the reaction in the reaction step, the oligomer that is a decomposition product of the polymer, and the alcohol formed by decomposing the organic peroxide , Ketones and the like can be discharged together with carbon dioxide, and a modified polypropylene resin with reduced volatile organic substances can be obtained.

The modified polypropylene resin is preferably pelletized once for use in forming a foamed layer or a non-foamed layer.
Therefore, in the method for producing a modified polypropylene resin according to the present embodiment, the kneaded material is extruded into a sheet shape or a strand shape from a die attached to the tip of the extruder, and then the modified polypropylene resin sheet or the modified polypropylene resin strand. It is preferable that the sheet or strand is pelletized with a pelletizer.
In the method for producing the modified polypropylene resin of the present embodiment, the kneaded material is extruded into a strand shape from a die attached to the tip of the extruder, and the strand is intermittently cut at the outlet of the die to be pelletized. May be.

In the above, since the kneaded material is discharged in a shape having a large specific surface area such as a sheet or a strand, in the method for producing a modified polypropylene resin of this embodiment, carbon dioxide and volatile organic matter are produced from this sheet or strand. Can be efficiently discharged, and a modified polypropylene resin with less volatile organic substances can be obtained.
That is, the deaeration process in this embodiment can be performed by a method in which gas is discharged from the kneaded material by spontaneous release when the kneaded material is extruded from the extruder.

The carbon dioxide addition step is preferably carried out under conditions where carbon dioxide is in a supercritical state in that a modified polypropylene resin with reduced volatile organic substances is easily obtained. It is preferable to bring carbon into a supercritical state.
At this time, when the amount of carbon dioxide added to the kneaded product is larger, the amount of volatile organic substances contained in the modified polypropylene resin can be reduced.
However, excessive addition of carbon dioxide may cause foaming in the modified polypropylene resin sheet or the modified polypropylene resin strand in the deaeration process.
The foamed modified polypropylene-based resin pellet can cause the formation of coarse bubbles in the foam layer when the laminated foam sheet is produced by the coextrusion method, or cause the resin to break in the non-foam layer.

From the above, it is preferable that the amount of carbon dioxide used in the carbon dioxide addition step is 1.0 part by mass or more and 4.0 parts by mass or less with respect to 100 parts by mass of the produced modified polypropylene resin. More preferably, the content is 2.0 parts by mass or more and 3.0 parts by mass or less.
In addition, if necessary, for example, a mixed gas containing a small amount of a hydrocarbon having a carbon number of 5 or less such as methane, ethane, or propane, or nitrogen (for example, 95% by mass or more of CO ₂ and 5% by mass or less). The carbon dioxide addition step may be performed using a mixed gas containing other gas).
When such a mixed gas is used, the ratio is preferably within the above range.

In this embodiment, instead of the carbon dioxide addition step performed before pelletization, the carbon dioxide addition step may be performed after pelletization. In addition to the carbon dioxide addition step before pelletization, carbon dioxide after pelletization may be performed. An addition step may be performed.
The carbon dioxide addition step for the pelletized modified polypropylene resin includes, for example, placing the modified polypropylene resin pellets in a pressure vessel and introducing carbon dioxide in a supercritical state into the pressure vessel. It can be carried out by such a method that the pellet is impregnated with carbon dioxide in a supercritical state.
In this case, the degassing step can be performed by discharging carbon dioxide from the pressure vessel after a predetermined time has elapsed, and reducing the pressure vessel to atmospheric pressure or lower as necessary.

  The modified polypropylene resin thus obtained can be used as a raw material for the laminated foam sheet of the present embodiment (first polypropylene resin composition, second polypropylene resin composition) as it is or blended with other polymer components. ).

As a polymer component used in addition to the modified polypropylene resin as a raw material for the laminated foam sheet, an unmodified polypropylene resin is preferable.
Examples of the polypropylene resin include those exemplified above as starting materials for the modified polypropylene resin.
As the polypropylene resin constituting the laminated foam sheet together with the modified polypropylene resin, a soft resin obtained by a multistage polymerization method is preferable.

That is, the polypropylene-based resin includes a first stage in which homopolymerization of propylene or random copolymerization of propylene and ethylene, and ethylene and one or more types of α-olefin having 3 or more carbon atoms after the first stage. What is obtained through the process of at least 2 steps | paragraphs with the 2nd step which performs copolymerization is preferable.
In the case where a polymer component other than the modified polypropylene resin is contained in the first polypropylene resin composition or the second polypropylene resin composition, the modified polypropylene resin and the other resin are, for example, 9: The mass ratio is preferably 1 to 1: 9 (modified polypropylene resin: other resin).
When other resins are used for forming the laminated foam sheet, the first polypropylene resin composition and the second polypropylene resin composition are also subjected to frequency dispersion dynamics at 200 ° C. in the same manner as the modified polypropylene resin. It is preferable that the phase angle obtained by viscoelasticity measurement is 30 ° or more and 70 ° or less at a frequency of 0.01 Hz.

The melt mass flow rate (MFR1) of the first polypropylene resin composition and the melt mass flow rate (MFR2) of the second polypropylene resin composition have a relationship of [MFR1 <MFR2]. Is preferred.
In order to obtain a good laminated foam sheet by the coextrusion method, it is desirable to lower the extrusion temperature as much as possible from the viewpoint of reducing the open cell ratio.
Since the first polypropylene resin composition contains a foaming agent when forming the foamed layer, the extrusion temperature can be lowered by the plasticizing effect of the foaming agent.
On the other hand, since it is difficult to expect the second polypropylene resin composition used for forming the non-foamed layer to exhibit such an effect, it is difficult to lower the extrusion temperature.
Therefore, in order to lower the extrusion temperature of the non-foamed layer, the melt mass flow rate (MFR1) of the first polypropylene resin composition and the melt mass flow rate (MFR2) of the second polypropylene resin composition are as described above. It is preferable to satisfy the relationship.

The first polypropylene resin composition containing the modified polypropylene resin can contain a foaming agent and a cell regulator necessary for forming the foamed layer, and the first polypropylene resin composition A foamed layer can be formed by extrusion foaming a product.
Examples of the blowing agent include hydrocarbons such as propane, n-butane, i-butane, n-pentane, i-pentane, and cyclopentane, halides thereof, carbon dioxide gas, and nitrogen.
Examples of the air conditioner include talc, mica, silica, diatomaceous earth, aluminum oxide, titanium oxide, zinc oxide, magnesium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, potassium carbonate, calcium carbonate, magnesium carbonate, Examples include inorganic compound particles such as potassium sulfate, barium sulfate and glass beads, and organic compound particles such as polytetrafluoroethylene.
Furthermore, azodicarbonamide, sodium hydrogen carbonate, a mixture of sodium hydrogen carbonate and citric acid, which also functions as a thermal decomposition type foaming agent, and the like can also be used as the bubble regulator.
The bubble regulator and the foaming agent do not need to be used singly and may be used in combination of two or more.

  The second polypropylene resin composition containing the modified polypropylene resin also contains components necessary for forming the non-foamed layer, and the second polypropylene resin composition is used as the first polypropylene resin composition. It can be coextruded with the product to form a non-foamed layer.

For the formation of such a laminated foam sheet, for example, equipment as shown in FIGS. 2 and 3 can be used.
FIG. 2 is a block diagram showing an example of a production apparatus used for production of the laminated foam sheet of the present embodiment. The first circular polypropylene resin composition containing a foaming agent is extruded and foamed from a circular die and is the same circular. After extruding the second polypropylene resin composition from the die in a non-foamed state to form a cylindrical laminated foam in which the non-foamed layer overlaps both surfaces of the foamed layer, the laminated foam is placed on the outer periphery of the cooling mandrel. FIG. 3 is a view showing a state in which the cooled laminated foam is vertically divided into two pieces and wound on a roll, and FIG. 3 is intended to show details of a portion indicated by a broken line circle A in FIG. An enlarged sectional view is shown.

  The manufacturing apparatus of the present embodiment includes a first extrusion line 70 for forming a foamed layer, a second extrusion line 80 for forming a non-foamed layer, and a first melt-kneaded in the first extrusion line 70. A joining mold 90 for joining the polypropylene resin composition and the second polypropylene resin composition melt-kneaded in the second extrusion line 80; and a first polypropylene resin composition joined by the joining mold; And a circular die 100 that extrudes the second polypropylene resin composition into a cylindrical shape.

  The joining mold 90 has a resin flow path formed therein so that the first polypropylene resin composition and the second polypropylene resin composition are cylindrical, and the first polypropylene resin composition The second polypropylene resin composition flows on both the inside and outside of the object.

    The laminated foam sheet manufacturing apparatus includes a cooling device CR1 for air-cooling the laminated foam FB discharged from the circular die 100 in a cylindrical shape from the inside, and a predetermined diameter by expanding the diameter of the cylindrical laminated foam FB. A cooling mandrel 200 for forming a cylindrical shape, a slitting device CT for slitting the laminated foam FB ′ after passing through the cooling mandrel 200 into two strip-like laminated foamed sheets 1, and a slit A winding roller 92 is provided for winding the strip-shaped laminated foamed sheet 1 after passing the plurality of rollers 91.

When the laminated foam sheet of this embodiment is manufactured, a modified polypropylene resin that exhibits a higher melt tension than a general polypropylene resin is employed as the foam layer forming material. Extrusion foaming with a high discharge amount from 100 is possible, and the cooling mandrel 200 can expand the diameter with a high blow-up ratio.
In the laminated foam sheet of the present embodiment, since the modified polypropylene resin is adopted as a material for forming the non-foamed layer, the non-foamed layer has a non-foamed layer for high-speed extrusion of the foamed layer and high-diameter expansion. Shows high follow-up and hardly breaks out of the resin.

In the laminated foam sheet of this embodiment, it is preferable to set the resin temperature of the second polypropylene resin composition to a certain level so as to reduce the load on the extruder of the second extrusion line 80.
If such conditions are set, the foamed layer that has been extruded and foamed is less likely to be cooled, so that the extrusion conditions are set such that bubble breakage is likely to occur in the foamed layer.
However, the laminated foam sheet of this embodiment has a low gel fraction and a high MFR of the modified polypropylene resin contained in the first polypropylene resin composition.
In other words, the laminated foam sheet of the present embodiment is the same as that of the extruder of the second extrusion line 80 because there are few gels that are the starting points for the tearing of the foam film, and excellent extensibility is exhibited in the foam film by the high MFR. While reducing the load, the foamed layer can be made into a dense and highly closed cell foamed state.

Therefore, the produced laminated foam sheet has excellent moldability in thermoforming and the like.
When the laminated foam sheet is deep-drawn like a cup container, the non-foamed layer is likely to run out of resin at the boundary between the bottom surface portion and the side surface portion. Such a problem is unlikely to occur because the layer contains a modified polypropylene resin and the modified polypropylene resin exhibits a high MFR.
That is, the laminated foam sheet of the present embodiment is effective not only for improving the efficiency during production but also for improving the yield of molded products.

Even if the blow-up ratio is such that drawdown is likely to occur with conventional laminated foam sheets, the laminated foam sheet of this embodiment is unlikely to cause drawdown.
Therefore, the laminated foam sheet of this embodiment can be produced with excellent production efficiency.
The laminated foam sheet is preferably produced under conditions where the blow-up ratio is 1.8 or more, and more preferably produced under conditions where the blow-up ratio is 2.3 or more.
The blow-up ratio is a value (D / d) obtained from the diameter (D) of the cooling mandrel with respect to the diameter (d) of the circular discharge port of the circular die, and the diameter (d) of the discharge port of the circular die. ) Means the diameter of a circle passing through the inner edge of the discharge port.
In addition, a laminated foam sheet with a thin non-foamed layer is prone to resin breakage in the non-foamed layer, but the laminated foam sheet of this embodiment does not cause resin breakage even in such a case. It can be said that it is effective in reducing the weight of the product.
In such a point, the laminated foam sheet of the present embodiment preferably has a non-foam basis weight of 100 g / m ² or less, and more preferably 50 g / m ² or less.

The laminated foam sheet is usually produced so that the apparent density of the foam layer is 0.025 g / cm ³ or more and 0.5 g / cm ³ or less.

The apparent density of the laminated foamed sheet is measured by the method described in JIS K7222: 1999 “Foamed Plastics and Rubber—Measurement of Apparent Density”, and specifically by the following method.
(Density measurement method)
A sample of 100 cm ³ or more was prepared from the laminated foam sheet, and this sample was conditioned in JIS K7100: 1999 symbol 23/50, second grade environment for 16 hours, and then its dimensions and mass were measured to obtain an apparent density. Is calculated by the following equation.

Apparent density (g / cm ³ ) = Sample mass (g) / Sample volume (cm ³ )

For example, a “DIGIMATIC” CD-15 type manufactured by Mitutoyo Corporation can be used for measuring the dimensions of the sample.

  In the laminated foam sheet, the open cell ratio of the foam layer is preferably 40% or less, and more preferably 30% or less.

The open cell ratio of the foam layer is measured by the following method.
That is, a plurality of sheet-like samples having a length of 25 mm and a width of 25 mm are cut out from the laminated foam sheet, and the cut samples are overlapped so that there is no gap to obtain a measurement sample having a thickness of 25 mm. Is measured to 1/100 mm using “Digimatic Caliper” manufactured by Mitutoyo Corporation, and the apparent volume (cm ³ ) is obtained.
Next, the volume (cm ³ ) of the sample for measurement is obtained by the 1-1 / 2-1 atmospheric pressure method using an air comparison type hydrometer 1000 type (manufactured by Tokyo Science).
The open cell ratio (%) is calculated from these obtained values and the following formula, and the average value of 5 tests is obtained.
The measurement is performed in a JIS K7100-1999 symbol 23/50, second grade environment after conditioning for 16 hours in a JIS K7100-1999 symbol 23/50, second grade environment.
The air-comparing hydrometer corrects with a standard sphere (large 28.9 cc, small 8.5 cc).

Open cell ratio (%) = 100 × (apparent volume−volume measured with an air-based hydrometer) / apparent volume

The laminated foam sheet of this embodiment is useful as a foam molded article such as a buffer sheet as it is, and also as a raw material for a foam molded article provided with a three-dimensional shape by thermoforming or the like.
Examples of the thermoforming include vacuum forming, pressure forming, vacuum / pressure forming, match mold forming, and press forming.
As a specific product produced by thermoforming, a container is preferable.
The foamed resin container thus produced is preferably used as various packaging containers because it is not only lightweight and high in strength, but also easily mass-produced.
In addition, the foamed resin container is preferably used for food packaging because it is excellent in heat insulation and the like.
A nonwoven fabric, metal foil, decorative paper, a printing film, or the like may be laminated on the surface of the foamed molded product of the present embodiment depending on the application.

In the present embodiment, the case where a modified polypropylene resin is used as a material for forming a laminated foam sheet is exemplified, but the modified polypropylene resin of the present invention can also be used for other applications.
That is, the present invention is not limited to the above examples.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.
Example 1
(1) Production of modified polypropylene-based resin First polypropylene-based resin (homopolypropylene resin, “PM600A” manufactured by Sun Allomer, MFR = 7.5 g / 10 min, density = 0.9 g / cm ³ ) and second polypropylene 100 parts by mass of a polypropylene resin obtained by mixing a resin based on homopolymer (homopolypropylene resin, “E111G” manufactured by Prime Polymer Co., Ltd., MFR = 0.5 g / 10 min, density = 0.9 g / cm ³ ) at 80/20; , T-butyl peroxybenzoate (“Kaya-Carbon BIC-75” manufactured by Kayaku Akzo Co., Ltd., 1 minute half-life temperature: 156 ° C.) and 0.84 parts by mass in a ribbon blender were mixed to obtain a mixture.
The obtained mixture was supplied to a twin screw extruder (L / D = 42) having a diameter of 41 mm, and a ratio of styrene monomer to 100 parts by mass of the polypropylene resin from the middle of the twin screw extruder using a liquid injection pump. Was supplied at 2.5 parts by mass.
The feed section is set to 170 ° C, the subsequent temperature is set to 230 ° C, the raw material composition is melted and kneaded in a twin-screw extruder under the conditions of a rotation speed of 120 rpm and a gear pump rotation speed of 25 rpm, and attached to the tip. The melt-kneaded product was extruded in a strand shape from a die having a diameter of 2 mm, a land of 10 mm, and a number of holes of 9 at a discharge rate of 45 kg / h.
Next, the extruded strand-shaped melt-kneaded product was cooled by passing through a cooling water tank containing 30 ° C. water.
The cooled strand kneaded material was cut with a pelletizer to obtain pellets of a modified polypropylene resin. Table 1 shows the results of the evaluation of the properties of the obtained resin composition pellets.

It was. )
(Examples 2-9, Comparative Examples 1-12)
The same procedure as described above was carried out except that the mixing ratio with the polypropylene resin and polypropylene resin used and the amount of organic peroxide were changed as shown in the following table.
In the table, “J105G”, “FY4”, “PL500A”, “E111G”, “E200GP”, and “J106” mean the following polypropylene resins.
“J105G”:
Homo polypropylene resin, “J105G” manufactured by Prime Polymer Co., Ltd., MFR = 9.0 g / 10 min, density = 0.9 g / cm ³

“J106”:
Homopolypropylene resin, “J106” manufactured by Prime Polymer Co., Ltd., MFR = 18.0 g / 10 min, density = 0.9 g / cm ³


“FY4”:
Homo polypropylene resin, “FY4” manufactured by Nippon Polypro Co., Ltd., MFR = 5.0 g / 10 min, density = 0.9 g / cm ³

“PL500A”:
Homo polypropylene resin, “PL500A” manufactured by Sun Allomer, MFR = 3.3 g / 10 min, density = 0.9 g / cm ³

“E111G”:
Homo polypropylene resin, “E111G” manufactured by Prime Polymer Co., Ltd., MFR = 0.5 g / 10 min, density = 0.9 g / cm ³

“E200GP”:
Homo polypropylene resin, “E200GP” manufactured by Prime Polymer Co., Ltd., MFR = 2.0 g / 10 min, density = 0.9 g / cm ³

  From the above, it can be seen that according to the present invention, it is possible to obtain a modified polypropylene resin that exhibits high melt tension, is excellent in fluidity, and has a low gel content.

1 Laminated foam sheet 10 Foam layer 20 Non-foam layer

Claims (3)

A method for producing a modified polypropylene resin, which comprises reacting an aromatic vinyl monomer with a polypropylene resin to produce a modified polypropylene resin having a higher melt tension than the polypropylene resin,
A first polypropylene resin exhibiting a melt mass flow rate of 4.0 g / 10 min or more under the measurement conditions of a temperature of 230 ° C. and a nominal load of 2.16 kg;
A second polypropylene resin having a melt mass flow rate of less than 4.0 g / 10 min;
An aromatic vinyl monomer;
A method for producing a modified polypropylene resin, in which an admixture containing an organic peroxide is melt-kneaded to react the aromatic vinyl monomer with the polypropylene resin. The mass percentage of the first polypropylene resin occupying the total value of the mass of the first polypropylene resin and the mass of the second polypropylene resin used for the melt-kneading is a ₁ (%), and the second polypropylene resin The mass percentage of a is defined as a ₂ (%),
The value of the melt mass flow rate of the first polypropylene resin is A ₁ (g / 10 min),
The value of the melt mass flow rate of the second polypropylene resin is A ₂ (g / 10 min),
The method for producing a modified polypropylene resin according to claim 1, wherein the following relational expression (x) is satisfied.

[A ₁ × a ₁ + A ₂ × a ₂ ] / 100> 4.0 (x)
The method for producing a modified polypropylene resin according to claim 1 or 2, wherein a modified polypropylene resin satisfying all of the following (a), (b), and (c) is produced.

(A) Melt tension at a temperature of 230 ° C. is 15 cN or more (b) Melt mass flow rate is 0.7 g / 10 min or more under measurement conditions of a temperature of 230 ° C. and a nominal load of 2.16 kg (c) Gel content is 1. 0% by mass or less

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