JP4547972B2 - Polypropylene resin laminated foam sheet and molded body - Google Patents

Description

  The present invention relates to a polypropylene-based resin laminated foam sheet that is excellent in rigidity and capable of obtaining a molded article having a beautiful appearance.

  Foamed sheets made of thermoplastic resins are generally lightweight, have good heat insulation and buffering properties against external stress, and can be easily obtained by heat forming such as vacuum forming. It is widely used in applications such as food containers, cushioning materials, heat insulating materials, and automobile parts, mainly polyethylene resins.

  Among them, a foam sheet using a polypropylene resin as a base resin is superior in heat resistance and oil resistance to conventional polystyrene resin foam sheets due to the characteristics of the base resin, but has poor appearance and rigidity. Sufficient and these improvements are needed.

  Therefore, in order to eliminate the inconvenience, a method (Patent Document 1) is disclosed in which a non-foamed resin layer or a film layer is laminated on a polypropylene resin foam sheet by thermal lamination. However, in this method, in order to strengthen the adhesion between the foamed layer and the non-foamed layer, excessive heat must be applied to the non-foamed resin layer and the film layer. As a result, the film of the obtained laminated foamed sheet Inconveniences such as surface roughness and loss of gloss occurred.

  In order to solve these problems, a method of laminating a polypropylene non-foamed layer or a polypropylene resin film on one side of a polypropylene resin foamed sheet by an extrusion laminating method (Patent Document 2) has been proposed. By this method, it became possible to obtain a polypropylene resin laminated foam sheet having excellent appearance, rigidity and heat resistance.

However, even if the polypropylene-based resin laminated foam sheet obtained by this method is used, the rigidity of the molded body may be insufficient depending on the desired shape. For example, in a molded body having a deep shape, a shape having a small taper angle of the side wall of the molded body, a shape having a partition portion, etc., the sheet is likely to be partially stretched at the molded body side wall or partition portion during heat molding, As a result, there is a problem that the rigidity of the entire molded body is lowered.
Japanese Patent No. 3140847 JP 2001-310429 A

  An object of the present invention is to provide a polypropylene resin laminated foam sheet that is excellent in rigidity and capable of obtaining a molded article having a beautiful appearance.

  As a result of intensive studies to solve such problems, the present inventor has laminated a polypropylene resin film on both sides of a polypropylene resin foam sheet through a non-foamed polypropylene resin layer formed by extrusion lamination. The present inventors have found that a polypropylene-based resin laminated foam sheet capable of obtaining a molded article having excellent rigidity and appearance can be obtained in a molded article having a deep shape or a partition shape, and has led to the present invention.

That is, the present invention
Via a non-foamed polypropylene resin layer having a thickness of 20~150μm formed by extrusion laminating a polypropylene resin, polypropylene resin films are laminated on both surfaces of the foamed polypropylene resin sheet, the foamed polypropylene resin sheet A raw material polypropylene resin, an isoprene monomer, and a radical polymerization initiator, wherein the base resin used is a polypropylene resin having an equilibrium compliance of less than 1.2 × 10 ⁻³ Pa ⁻¹ under a temperature of 210 ° C. A polypropylene- based resin laminated foam sheet (Claim 1), which is a modified polypropylene resin obtained by melt-kneading
Polypropylene resin used in the non-expanded polypropylene resin layer, characterized in that a melt flow rate 4~20g / 10 min under conditions of temperature 230 ° C. and a load 21.18 N, polypropylene of claim 1, wherein Resin laminated foam sheet (Claim 2),
^3. The polypropylene according to claim 1, wherein the polypropylene resin foam sheet has a density of 0.1 to 0.5 g / cm ³ , a closed cell ratio of 60% or more, and a number of cells of 5 or more in the thickness direction. -Based resin laminated foam sheet (Claim 3), and
The molded object obtained by heat-molding the polypropylene-type resin laminated foam sheet in any one of Claims 1-3 ( Claim 4 ).
About.

  According to the present invention, it is possible to obtain a polypropylene-based resin fat laminated foam sheet capable of obtaining a molded article having excellent appearance and rigidity. In particular, since the polypropylene-based resin laminated foam sheet of the present invention has higher rigidity than that of the prior art sheet, it can be suitably used in molding a deep shape or a shape having partitions.

  Embodiments of the present invention will be described based on specific examples, but the implementation of the present invention is not limited thereto.

The present invention provides a polypropylene resin laminated foamed sheet through a polypropylene-based resin layer having a thickness of 20~150μm formed by extrusion laminating a polypropylene resin, polypropylene-based resin film is laminated on both surfaces of the foamed polypropylene resin sheet It is characterized by having.

  Laminating a polypropylene resin film on both sides of a polypropylene resin foam sheet by extrusion laminating as in the present invention is a molded product having a deep shape and a partition as compared to the case of laminating on one side. Is preferable from the viewpoint of excellent rigidity and appearance of the obtained molded body.

  The polypropylene resin foam sheet and the polypropylene resin laminated film used in the present invention are laminated via a non-foamed polypropylene resin layer formed by extrusion laminating a polypropylene resin. A typical method of extrusion lamination will be described with reference to FIGS. 1 and 2.

As a method for producing a polypropylene resin laminated foam sheet 10 composed of the polypropylene resin foam sheet 1, the non-foamed polypropylene resin layer 7 and the polypropylene resin film 8 in the present invention, the foam sheet 1 is placed along the nip roll 2. The non-foamed resin layer 7 melted from the T die 4 is extruded into a film shape between the nip roll 2 and the cooling roll 3, and the film 8 is expanded along the expander roll (roll for removing wrinkles of the film 8) 9. Then, the foamed sheet 1 is taken out while the film 8, the non-foamed resin layer 7 and the foamed sheet 1 are pressure-bonded by the nip roll 2 and the cooling roll 3 while being pressed into the gap 6 between the nip roll 2 and the cooling roll 3. And a non-foamed resin layer 7 and a laminated film 8 are obtained. At this time, the temperature of the non-foamed resin layer 7 extruded from the T die 4 is adjusted, and the distance (air gap 5) until the foamed resin layer 7 coming out of the T die 4 is pressure-bonded to the foamed sheet is adjusted. Thereby, the peeling strength of the non-foamed resin layer 7 and the laminated film 8 which were press-bonded can be adjusted.
Further, by using the obtained laminated foamed sheet 10 and laminating by the same method on the surface where the non-foamed polypropylene resin layer 7 and the polypropylene resin film 8 are not laminated, as shown in FIG. The polypropylene resin laminated foam sheet in the invention can be obtained.

  Examples of the polypropylene resin constituting the non-foamed polypropylene resin layer in the present invention include a propylene homopolymer, a block copolymer of propylene and another monomer, or a random copolymer of propylene and another monomer. Polymers and the like can be mentioned, but the polypropylene homopolymer is preferable from the viewpoint of high rigidity and low cost, and is a block copolymer of propylene and other monomers from the viewpoint of low temperature brittleness. Is preferred. When the polypropylene resin is a block copolymer of propylene and another monomer, or a random copolymer of propylene and another monomer, the high crystallinity and high rigidity characteristic of the polypropylene resin From the viewpoint of maintaining good chemical resistance, the propylene monomer component contained is preferably 75% by weight or more, and more preferably 90% by weight or more.

  In the non-foamed polypropylene resin layer, not only a polypropylene resin but also two or more kinds can be mixed and used. Furthermore, what mixed the high density polyethylene, the low density polyethylene, the linear low density polyethylene, the ethylene-propylene copolymer, the ethylene-butene copolymer, the butene resin etc. can be used for a polypropylene resin.

  The melt flow rate of the resin used in the non-foamed polypropylene resin layer of the present invention under the conditions of a temperature of 230 ° C. and a load of 21.18 N is 4 to 20 g / 10 minutes from the viewpoint of processability and secondary moldability. It is desirable. If the melt flow rate under the above conditions is less than 4 g / 10 min, the thickness of the non-foamed resin layer is likely to be uneven, and at the same time the appearance of the molded product is impaired, the rigidity of the molded product tends to be partially reduced. is there. Further, even when heat-softening during secondary molding, it does not soften to the extent that it is suitable for mold shaping, and tends to cause partial elongation at the side wall of the molded body, partition-shaped part, etc., and to reduce the rigidity of the molded body. On the other hand, if the melt flow rate exceeds 20 g / 10 minutes, it is difficult to handle the non-foamed resin layer during lamination processing, and the phenomenon of neck-in in which the non-foamed resin layer extruded from the T die contracts in the T die width direction increases. This tends to make it difficult to control the width of the non-foamed resin layer. In addition, the melt flow rate of the polypropylene resin in this specification is measured according to JIS K7210.

  The melt tension at a temperature of 270 ° C. of the polypropylene resin constituting the non-foamed polypropylene resin layer in the present invention is desirably less than 0.6 cN. When the melt tension is 0.6 cN or more, when the non-foamed polypropylene resin layer is laminated on the polypropylene resin foam sheet, the thickness of the non-foamed polypropylene resin layer is likely to be uneven. As a result, the appearance of the molded body and the rigidity of the molded body tend to be impaired.

  In addition, the melt tension of the polypropylene resin in the present invention can be measured by the following method. Using a melt tension tester manufactured by Toyo Seiki Co., Ltd., a polypropylene resin heated to 270 ° C. was extruded into a strand shape from an orifice having a diameter of 2.095 mm and a length of 8 mm at a speed of 10 mm / min, and the strand material was a pulley for detecting tension. Then, the winding speed is gradually increased at a rate of about 5 rpm / second, and the tension value is measured when the strand is cut.

  The thickness of the non-foamed polypropylene resin layer used in the method of the present invention is preferably 20 μm to 150 μm, more preferably 30 μm to 120 μm, and even more preferably 50 μm to 100 μm from the viewpoints of adhesiveness, lightness, and rigidity. When the thickness of the non-foamed polypropylene resin layer is less than 20 μm, the effect of reinforcing the rigidity of the foamed sheet of the present invention tends to be small. When the thickness of the non-foamed polypropylene resin layer exceeds 150 μm, the rigidity of the foamed sheet is improved, but the lightness and cost tend to be inferior. The thickness of the non-foamed polypropylene resin layer used in the present invention can be adjusted by controlling the discharge amount of the resin extruded from the T-die and the sheet take-up speed.

  The polypropylene resin film used in the present invention is an unstretched or biaxially stretched polypropylene film made of a polypropylene resin such as a polypropylene homopolymer or a polypropylene copolymer. The polypropylene resin film may be a multilayer film having two or more layers.

  The polypropylene resin film in the present invention is laminated on both sides of the polypropylene resin foam sheet, but the same type or different types of polypropylene resin films are combined depending on the application, desired shape, rigidity of the molded product, desired design properties, etc. Can be used.

  Of the combinations of the polypropylene resin films laminated on both surfaces in the present invention, the polypropylene resin film on at least one surface is preferably a biaxially stretched polypropylene resin film. By using a biaxially stretched polypropylene resin film, the effect of reinforcing the rigidity of the present invention can be more preferably applied because the effect of suppressing the partial elongation of the molded body at the time of molding and making it uniform around the meat is great. . In addition, when printing to give design properties to the film, the biaxially stretched polypropylene-based resin film suppresses partial elongation of the molded body and has a uniform pattern around the pattern by printing. Hard to lose. In addition, since the biaxially stretched polypropylene resin film has the property of being heat-shrinked, the drawdown during the heat molding of the laminated foam sheet is reduced, and the molding failure due to the drawdown can be avoided.

  15-80 micrometers is preferable, as for the thickness of the polypropylene resin film in this invention, 20-70 micrometers is more preferable, and 25-60 micrometers is more preferable. When the thickness of the polypropylene resin film is less than 15 μm, the film may be broken by stretching at the time of heat molding of the obtained laminated foamed sheet, and the moldability tends to be inferior. When the thickness exceeds 80 μm, the rigidity is improved, but the lightweight property of the laminated foam sheet tends to be insufficient.

  The peel strength between the polypropylene resin foam sheet and the polypropylene resin laminate film in the polypropylene resin laminate foam sheet of the present invention is preferably 1.5 N / 25 mm or more. When the peel strength is smaller than 1.5 N / 25 mm, the film layer may swell during molding heating of the obtained laminated foam sheet, and a good molded product may not be obtained. In addition, the measurement of the peeling strength of the laminated | multilayer film of a laminated foam sheet and a foamed layer cuts out the test piece of 25 mm in width from a laminated foam sheet based on JISZ0230, and performs a 180 degree peeling test with the peeling speed of 100 mm / min.

  The polypropylene resin laminated foam sheet of the present invention can be laminated by forming a printed layer on the surface of the polypropylene resin laminated film that adheres to the non-foamed resin layer in order to impart design properties.

  The printing layer in the present invention is formed by printing with an ink whose main component is a mixture of resin, solvent and pigment. Resins for printing inks include copolymers of vinyl chloride and vinyl acetate, chlorinated products of rubber, chlorinated products of polyvinyl acetate, chlorinated products of polypropylene, polymers of acrylic acid and its derivatives, condensation of dimer acid and polyamine Products, polyester or polyether and diisocyanate polymers, cell source nitrate ester compounds, and the like. Moreover, you may use those resin 1 type or in mixture of 2 or more types. In particular, chlorinated polypropylene is preferable from the viewpoint of adhesiveness with a polypropylene resin. Moreover, you may add an anchor coating agent, an antistatic agent, a stabilizer, antioxidant, a dispersing agent etc. to printing ink as needed. However, the printing layer is not limited to the above as long as the object of the present invention can be achieved.

  In the present invention, an anchor coating agent can be used to improve the adhesion between the printed layer and the foamed sheet. As the anchor coating agent, an anchor coating agent (for example, XGL-1200 manufactured by Sakata Inx Co., Ltd.) or an adhesive / primer treatment agent used for improving the printability and adhesiveness of a polypropylene resin that is generally used can be used. Among them, solvent-based and aqueous-based ones that are easy to apply are preferable from the viewpoint of applying a small basis weight. Since it is a solvent system or an aqueous system, the solvent and water are volatilized by coating and drying, and coating with a desired basis weight can be easily performed.

  The printing layer in the present invention is formed by a known method such as gravure printing. There is no particular limitation on the pattern of printing. By arranging the printed layer on the inner surface (the foamed layer side of the polypropylene resin layer film), it is possible to obtain a laminated foam sheet and a laminated foam having gloss and excellent design. Can do.

  As the polypropylene resin of the base resin used in the production of the foam sheet of the present invention, an electron beam is applied to a linear polypropylene resin (hereinafter, this polypropylene resin may also be referred to as “raw polypropylene resin”). Irradiated long chain branches (for example, HMS-PP manufactured by Sun Allomer Co., Ltd.) and modified polypropylene resins obtained by melt-kneading raw material polypropylene resins, isoprene monomers and radical polymerization initiators are foamable. It is preferable from the point of being excellent. In particular, a modified polypropylene resin obtained by melt-kneading a raw material polypropylene resin, an isoprene monomer, and a radical polymerization initiator is preferable because it can be easily manufactured and can be manufactured at low cost.

The polypropylene resin used in the production of the polypropylene resin foam sheet in the present invention has a smaller drawdown at the time of heat molding of the laminated foam sheet, and can avoid molding defects caused by the drawdown. The measured equilibrium compliance J _eo is preferably less than 1.2 × 10 ⁻³ Pa ⁻¹ .

In this specification, the equilibrium compliance J _eo is measured using a rheometer SR-2000 manufactured by Rheometric Scientific, by the following method. After sandwiching a molded product of polypropylene resin having a thickness of 3 mm between two parallel disks and maintaining the temperature at 210 ± 1 ° C. and sufficiently melting, the interval between the parallel disks is adjusted to 1.4 mm, Remove the resin protruding from the disc. Next, at time t = 0, one disk is rotated with respect to the other so that the stress σc applied to the sample is maintained at a constant value of 100 N / m ² , and the strain amount γ ( t) is measured over time.

  Next, the creep compliance J (t) defined by the following equation (1) is plotted against the time t from the start of giving the stress σc.

After sufficient time has elapsed, the creep compliance J (t) has a linear relationship with the time t, and the equilibrium compliance is a linear relationship between the creep compliance J (t) and the time t. Is given as an intercept when the extrapolated portion at time t = 0.

  The raw material polypropylene-based resin is one or more of a propylene homopolymer, a block copolymer with a copolymerizable α-olefin, and a random copolymer, and a crystalline polymer is used. can give. As propylene copolymers, those containing propylene in an amount of 75% by weight or more, particularly 90% by weight or more, are retained in the crystallinity, rigidity, chemical resistance, etc., which are characteristic of polypropylene resins. preferable. The other monomer copolymerizable with propylene is one or more selected from the group consisting of ethylene, α-olefin, cyclic olefin, diene monomer and vinyl monomer. Monomer. Of these monomers, ethylene or butene-1 is preferable because it is inexpensive.

  The molecular weight (weight average molecular weight) of the raw material polypropylene resin is preferably in the range of 50,000 to 2,000,000 from the viewpoint of industrial availability, and from the point of being inexpensive, it is 100,000 to 1,000,000. More preferably, it is within the range.

  You may add other resin or rubber | gum to the said raw material polypropylene resin in the range which does not impair the effect of this invention as needed. The amount of other resin or rubber added to the raw material polypropylene resin is different depending on the type of this resin or the type of rubber, and as long as it is within the range not impairing the effects of the present invention as described above, Usually, it is preferably about 25% by weight or less.

  Furthermore, the raw material polypropylene resin may contain an antioxidant, a metal deactivator, a phosphorus processing stabilizer, an ultraviolet absorber, an ultraviolet stabilizer, a fluorescent brightener, a metal soap, an antacid adsorbent as necessary. Stabilizers such as, or crosslinking agents, chain transfer agents, nucleating agents, lubricants, plasticizers, fillers, reinforcing materials, pigments, dyes, flame retardants, antistatic agents, and other additives do not impair the effects of the present invention You may add within the range.

  The polypropylene resin foam sheet made of the polypropylene resin in the present invention is prepared by, for example, melting and kneading a polypropylene resin and a foaming agent in an extruder, adjusting the foaming temperature in the extruder, and forming a circular die having an annular lip. Used to extrude into the atmospheric pressure from the lip of the die to obtain a cylindrical foam, and then, after taking out the cylindrical foam, by a molding process with a cooling cylinder (mandrel), after stretching and cooling, open, It is easily manufactured by a sheet-like method. Further, extrusion foaming may be performed continuously with the production of the modified polypropylene resin composition.

  Examples of the blowing agent include aliphatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, inorganic gases, water, and the like. Moreover, you may use combining those 1 type (s) or 2 or more types. The addition amount (kneading amount) of the foaming agent varies depending on the type of foaming agent and the target foaming ratio, but is usually in the range of 0.5 to 10 parts by weight with respect to 100 parts by weight of the polypropylene resin composition. Is preferred.

  In the present invention, a nucleating agent such as sodium bicarbonate-citric acid mixture or talc may be used in combination as necessary in order to control the cell diameter of the polypropylene resin foam sheet to an appropriate size. Although there is no restriction | limiting in particular in the addition amount of this nucleating agent used as needed, Usually, it is preferable that it is 0.01-3 weight part with respect to 100 weight part of polypropylene resin compositions.

  In the production of the polypropylene resin foam sheet of the present invention, a thermoplastic resin may be mixed within a range not impairing the foamability of polypropylene.

  For the purpose of obtaining a desired cell structure, the polypropylene resin foam sheet made of the polypropylene resin in the present invention is, for example, promoted cooling by blowing air to the surface after extrusion foaming, or stretched when taken into a mandrel May be.

  The polypropylene resin used in the polypropylene resin foam sheet of the present invention includes, as necessary, an antioxidant, a metal deactivator, a phosphorus processing stabilizer, an ultraviolet absorber, an ultraviolet stabilizer, a fluorescent whitening agent, Stabilizers such as metal soaps and antacid adsorbents, or additives such as crosslinking agents, chain transfer agents, nucleating agents, lubricants, plasticizers, fillers, reinforcing materials, pigments, dyes, flame retardants, antistatic agents It may be added.

The density of the polypropylene resin foam sheet in the present invention is preferably 0.1 to 0.5 g / cm ³ . When it is smaller than 0.1 g / cm ³ , the rigidity is poor, and when it is larger than 0.5 g / cm ³ , the heat insulating property is poor.

  The closed cell ratio of the polypropylene resin foam sheet of the present invention is 60% or more, preferably 70% or more, more preferably 80% or more. If it is less than 60%, the molded product obtained by heating may be inferior in rigidity.

  1-5 mm is preferable and, as for the thickness of the polypropylene resin foam sheet in this invention, 1-3 mm is more preferable. When the thickness of the polypropylene resin foam sheet is less than 1 mm, the heat insulating property, rigidity and buffering property tend to be inferior, and when it is larger than 5 mm, the moldability tends to be inferior.

  The number of cells in the thickness direction of the polypropylene resin foam sheet of the present invention is preferably 5 or more, and more preferably 7 or more. When the number of bubbles in the thickness direction is smaller than 5, the heat insulating property and the surface property are inferior.

The basis weight of the polypropylene resin laminated foam sheet made of the polypropylene resin foam sheet, non-expanded polypropylene resin layer and polypropylene resin film produced in the present invention is preferably 0.23 to 0.60 kg / m ² , 0 27-0.55 kg / m ² is more preferable. If the basis weight of the laminated foam sheet is less than 0.23 kg / m ² , there is a tendency that sufficient rigidity cannot be obtained. When the basis weight exceeds 0.60 kg / m ² , the rigidity is sufficiently obtained, but the lightness and cost tend to be inferior.

  The width of the polypropylene resin laminated foam sheet of the present invention is preferably 600 mm or more and more preferably 1000 mm or more because the number of molded products can be increased at the time of thermoforming and the productivity is high.

  The polypropylene-based resin laminated foam sheet in the present invention is excellent in heat moldability such as plug molding, vacuum molding, and pressure-air molding, so that a molded article having excellent lightness and rigidity and a beautiful appearance can be obtained. In particular, since the polypropylene-based resin laminated foam sheet in the present invention has higher rigidity than the sheet of the prior art, it can be suitably used in molding a deep shape or a shape having partitions.

  Examples of thermoforming include plug molding, matched mold molding, straight molding, drape molding, plug assist molding, plug assist / reverse draw molding, air slip molding, snapback molding, reverse draw molding, free drawing molding, plug Examples include AND ridge molding and ridge molding.

  EXAMPLES Next, although this invention is demonstrated in detail based on an Example, this invention is not limited to this Example.

(Measurement of density of foam sheet)
Measurement was performed in accordance with JIS-K6767.

(Measurement of closed cell ratio of foam sheet)
In accordance with the method described in ASTM D2856, measurement was performed with an air pycnometer.

(Measurement of foam sheet thickness)
Measurement points are provided at intervals of 30 mm in the width direction of the foamed sheet, and after measuring the thickness of each measurement point using a thickness gauge (a thickness gauge manufactured by teclock), the average of the measured values at each point is taken as the thickness of the foamed sheet. .

(Measurement of the number of cells in the thickness direction of the foam sheet)
Ten measurement points were provided at equal intervals in the width direction of the foamed sheet, and the number of cells in the thickness direction at the measurement points was measured using a loupe (peacock, pocket micro × 10). Then, the average of the measured value of each point was made into the number of cells of the thickness direction.

  Below, the manufacturing method of the laminated foam sheet used for the Example and the comparative example and the evaluation method of a molded object are shown.

(Foamed sheet base resin X)
As the base resin X of the foam sheet, 100 parts by weight of homopolypropylene (Grand Polymer, J103WB), 0.25 parts by weight of radical polymerization initiator (t-butylperoxybenzoate) and 0.5 parts by weight of isoprene are biaxial. Pellets of modified polypropylene resin were obtained by melt-kneading with an extruder. In addition, the equilibrium compliance of this base resin X was 0.8 × 10 ⁻³ Pa ⁻¹ .

(Foamed sheet base resin Y)
As the base resin Y of the foam sheet, PF-814 manufactured by Sun Allomer Co., which is a commercially available modified polypropylene resin, was used. In addition, the equilibrium compliance of this base resin Y was 1.9 × 10 ⁻³ Pa ⁻¹ .

[Method for producing foam sheet]
(Foamed sheet A-1)
90- blend of 100 parts by weight of the foam sheet base resin X, 0.05 parts by weight of blend oil, and 0.5 parts by weight of a cell nucleating agent (Celbon SC / K manufactured by Eiwa Kogyo Co., Ltd.) was stirred and mixed with a ribbon blender. After being supplied to a 125 mmφ tandem type extruder and melted in a first stage extruder (90 mmφ) set at 200 ° C., isobutane was used as a foaming agent in an amount of 1. with respect to 100 parts by weight of the modified polypropylene resin composition. 7 parts by weight is injected and mixed, cooled in a second stage extruder (125 mmφ) set at 160 ° C. (measured by a temperature sensor installed at the resin inflow part of the die), and discharged from the circular die (127 mmφ) under atmospheric pressure. extension and, with molded in a cooling tube outer diameter 335mmφ and body length 800 mm, while take-off so that the basis weight of the foam sheet is 240 g / ^{m 2} And cooling to obtain a cylindrical foam, which was obtained foamed sheet 1035mm width by cutting open with a cutter. The obtained foamed sheet had a density of 0.14 g / cm ³ , a closed cell ratio of 78%, an average thickness of 1.9 mm, and a number of bubbles of 8.1 pieces / thickness.

(Foamed sheet A-2)
90-125 mmφ in a blend of 100 parts by weight of the foamed sheet base resin Y, 0.05 parts by weight of blend oil, and 0.7 parts by weight of a cell nucleating agent (Celbon SC / K manufactured by Eiwa Kogyo Co., Ltd.) by stirring with a ribbon blender. After being supplied to a tandem type extruder and melted in a first stage extruder (90 mmφ) set at 200 ° C., 1.5% of isobutane as a foaming agent was added to 100 parts by weight of the modified polypropylene resin composition. The mixture was pressed into parts by weight, cooled in a second stage extruder (125 mmφ) set at 160 ° C. (measured by a temperature sensor installed at the resin inflow part of the die), and discharged from the circular die (127 mmφ) under atmospheric pressure. While being molded in a cooling cylinder having an outer diameter of 335 mm and a main body length of 800 mm, the foamed sheet was drawn and cooled so that the basis weight was 240 g / m ^2. A cylindrical foam was obtained, and the foamed sheet having a width of 1035 mm was obtained by cutting it with a cutter. The obtained foamed sheet had a density of 0.147 g / cm ³ , a closed cell ratio of 82%, an average thickness of 1.8 mm, and a number of bubbles of 9.2 / thickness.

(Foamed sheet A-3)
A foam sheet having a width of 1035 mm was obtained in the same manner as the foam sheet A-1 except that the basis weight of the foam sheet was 400 g / m ² . The obtained foamed sheet had a density of 0.14 g / cm ³ , a closed cell ratio of 74%, an average thickness of 2.7 mm, and a number of bubbles of 8.3 / thickness.

[Non-foamed resin layer]
(Non-foamed resin layer B-1)
As the non-foamed resin layer, Chisso Homopolypropylene CS3230 (melt flow rate under conditions of a temperature of 230 ° C. and a load of 21.18 N was 10 g / 10 min) was used.

(Non-foamed resin layer B-2)
As the non-foamed resin layer, Homopolypropylene PM801Z manufactured by Sun Allomer Co., Ltd. (melt flow rate under conditions of a temperature of 230 ° C. and a load of 21.18 N was 13 g / 10 min) was used.

(Non-foamed resin layer B-3)
Homopolypropylene J103WB manufactured by Grand Polymer Co., Ltd. (melt flow rate under conditions of a temperature of 230 ° C. and a load of 21.18 N was 3 g / 10 min) was used as the non-foamed resin layer.

[Polypropylene resin film]
(Polypropylene resin film C-1)
As the polypropylene resin film, an unstretched polypropylene film having a thickness of 25 μm and a width of 1020 mm (manufactured by Tonen Corporation, Polyace 25H) was used.

(Polypropylene resin film C-2)
A biaxially stretched polypropylene film (manufactured by Santox, MF20) having a thickness of 30 μm and a width of 1020 mm was used as the polypropylene resin film.

[Extrusion lamination method]
Using the extrusion laminating equipment shown in FIG. 1, the foamed sheet 1 is fed between the nip roll 2 and the cooling roll 3 along the nip roll 2, and the non-foamed resin layer 7 melted from the T-die 4 is extruded into a film shape. Further, the laminated film 8 is placed along the expander roll 9 and fed into the gap 6 between the nip roll 2 and the cooling roll 3, and the laminated film 8, the non-foamed resin layer 7 and the foamed sheet 1 are pressure-bonded by the nip roll 2 and the cooling roll 3. Then, a laminated foamed sheet 10 composed of the foamed sheet 1, the non-foamed resin layer 7 and the laminated film 8 was produced.
In the production of the laminated foamed sheet 10, the resin temperature of the non-foamed resin layer 7 immediately after being extruded from the T die 4 is 240 ° C., and the distance until the foamed resin layer coming out of the T die 4 is pressed onto the foamed sheet. (Air gap 5) was 20 cm, and the width of the non-foamed resin layer 7 was 1030 mm. Here, in the measurement of the resin temperature, the center part of the non-foamed polypropylene resin layer 7 extruded from the T die 4 into a film shape using a non-contact temperature sensor (THERMO-HUNTER PT-3LF manufactured by Optics). Was measured as the resin temperature of the polypropylene resin.

  The laminated surface “single side” in Table 1 represents a state in which the non-foamed resin layer and the laminated film are laminated on one side of the foamed sheet, and the laminated surface “both sides” represents that of the foamed sheet by performing the same procedure as described above again. This represents a state in which a non-foamed resin layer and a laminated film are laminated on both sides.

[Preparation of molded article for evaluation]
The obtained laminated foamed sheet was formed into a m-width continuous molding machine using a mold having the shape shown in FIG. 3 (molded body size: opening 166 mmφ, bottom portion 84 mmφ, height 75 mm, number of picks: 25 / shot). A molded body for evaluation was obtained by continuous molding according to a matched mold molding method using FLC-415PB4-C3 (manufactured by Asano Laboratory Co., Ltd.).

[Appearance evaluation of laminated foam sheet]
The appearance of the obtained molded body was evaluated as follows. In particular, it was evaluated by paying attention to whether it is a uniform meat circumference or partially stretched on the side wall that is easily stretched to the sheet. If the side wall is partially stretched, the printing on the laminated film will be partially thinned, bubbles in the foam layer will be partially stretched, or the thickness of the side wall portion will be thinned. To lose.
○: There is no partial stretching, the circumference of the meat is uniform, and the appearance is good.
(Triangle | delta): The circumference | surroundings of the side wall are somewhat non-uniform | heterogenous by partial extending | stretching, and an external appearance is inferior somewhat.
X: Partial stretching is remarkably uneven around the side wall and the appearance is poor.

[Rigidity evaluation of molded body]
As shown in FIG. 4, a load cell attached to an autograph AG2000 manufactured by Shimadzu Corporation was provided with a 200 mmφ aluminum plate, and the molded body was compressed at 50 mm / min from the molded body opening by the autograph through the plate. Of the loads sensed by the loadle cell at this time, the load value that first yielded was the stiffness value.
Based on the measured rigidity value, the rigidity of the molded body was evaluated as follows.
○: The rigidity value of the molded body is 20 kgf or more. Δ: The rigidity value of the molded body is 15 kgf or more and less than 20 kgf. X: The rigidity value of the molded body is less than 15 kgf.

(Examples 1-5 and Comparative Examples 1-3)
Using the foamed sheet, non-foamed resin layer and laminated film shown in Table 1, a laminated foamed sheet was obtained by the above-described extrusion lamination method. In addition, Example 3 represents that the film F is laminated | stacked on the one side of the foam sheet, and the film G is laminated | stacked on one side. Moreover, the comparative example 5 represents that the non-foaming resin layer and the laminated | multilayer film are not laminated | stacked on the foam sheet. Using the obtained laminated foam sheet, a molded body was obtained by the method described above. Table 1 also shows the results of evaluating the appearance of the molded body and the rigidity of the molded body using the obtained molded body.

  As described above, by producing the laminated foam sheets as in Examples 1 to 5, a molded body having a uniform meat periphery, an excellent appearance, and a good molded body rigidity was obtained. On the other hand, in Comparative Examples 1 and 2, since the non-foamed resin layer was thin and laminated on only one side, the effect of improving the molded body rigidity was not obtained. In Comparative Example 3, since there was no laminated film and non-foamed resin layer, the appearance and rigidity of the molded product were inferior.

It is a figure which shows an example of the extrusion laminating method. It is a figure which shows an example of a polypropylene resin laminated foam sheet. It is a figure which shows the shaping | molding die used for the Example and the comparative example. It is a figure which shows the rigidity evaluation method implemented in the Example and the comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Foam sheet 2 Nip roll 3 Cooling roll 4 T die 5 Air gap (Distance until the non-foamed resin layer 7 which came out of T die 4 is crimped | bonded to the foam sheet 1)
6 Gap formed by nip roll 2 and cooling roll 3 7 Non-foamed resin layer 8 Film 9 Expander roll (roll for removing wrinkles of film 8)
10 Laminated foam sheet 11 Molded body for evaluation 12 Autograph 13 Load cell 14 Aluminum plate

Claims (4)

Via a non-foamed polypropylene resin layer having a thickness of 20~150μm formed by extrusion laminating a polypropylene resin, polypropylene resin films are laminated on both surfaces of the foamed polypropylene resin sheet, the foamed polypropylene resin sheet A raw material polypropylene resin, an isoprene monomer, and a radical polymerization initiator, wherein the base resin used is a polypropylene resin having an equilibrium compliance of less than 1.2 × 10 ⁻³ Pa ⁻¹ under a temperature of 210 ° C. A polypropylene- based resin-laminated foam sheet, which is a modified polypropylene resin obtained by melt-kneading a resin. Polypropylene resin used in the non-expanded polypropylene resin layer, characterized in that a melt flow rate 4~20g / 10 min under conditions of temperature 230 ° C. and a load 21.18 N, polypropylene of claim 1, wherein Resin laminated foam sheet. ^3. The polypropylene according to claim 1, wherein the polypropylene resin foam sheet has a density of 0.1 to 0.5 g / cm ³ , a closed cell ratio of 60% or more, and a number of cells of 5 or more in the thickness direction. -Based resin laminated foam sheet. The molded object obtained by heat-molding the polypropylene resin laminated foam sheet in any one of Claims 1-3 .

Images