JP2005119147A - Manufacturing method for polypropylene resin laminated foamed sheet, laminated foamed sheet and formed product thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a polypropylene resin laminated foamed sheet suitable for obtaining a formed product having the adhesive strength of a foamed sheet capable of withstanding use under a high temperature condition and a non-foamed resin layer, hard to produce foreign matter in the non-foamed resin layer and excellent in appearance, lightweight properties, design properties and processability, the polypropylene resin laminated foamed sheet and a formed product formed from the polypropylene resin laminated foamed sheet. <P>SOLUTION: In the manufacturing method for the polypropylene resin laminated foamed sheet 10 wherein a polypropylene non-foamed resin layer 7 is laminated at least on one side of a polypropylene foamed resin sheet 1, the polypropylene non-foamed resin layer of which the resin temperature immediately after extrusion is 210-250°C is laminated on the polypropylene foamed resin sheet within two sec, the polypropylene resin laminated foamed sheet and the formed product formed from the laminated foamed sheet are provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a polypropylene resin laminated foam sheet, a laminated foam sheet, and a molded article thereof.

  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 secondary molding such as vacuum molding. It is widely used in applications such as cushioning materials, food containers, heat insulating materials, and automotive parts, mainly resins and polyethylene resins.

  Among them, the foam sheet with polypropylene resin as the base resin is superior in heat resistance and oil resistance compared to conventional polystyrene resin foam sheets due to the characteristics of the base resin, but its appearance, rigidity, and light weight. These properties are insufficient, 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 a thermal laminating method. 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 There are inconveniences such as rough surface and loss of gloss.

  Moreover, the method (patent document 2) of laminating | stacking a polypropylene resin foam sheet and a non-foamed layer by the coextrusion method is also performed. However, the coextrusion method has a problem that it is difficult to balance the thickness of the non-foamed resin layer and the physical properties of the foamed layer.

In order to solve these problems, a method of laminating a polypropylene resin foam sheet and a non-foamed resin layer by an extrusion laminating method (Patent Document 3) is disclosed. This method makes it possible to obtain a polypropylene resin laminated foam sheet having excellent appearance, light weight, and heat resistance without worrying about the balance between the thickness of the non-foamed resin layer and the physical properties of the foamed layer. However, a polypropylene resin having specific molten resin properties must be used for the non-foamed resin layer. Also, foreign matter is generated in the non-foamed resin layer, and foaming is sufficient to withstand use at high temperatures. There is a problem that it is difficult to obtain an adhesive strength between the sheet and the non-foamed resin layer.
Japanese Patent No. 3140847 Japanese Patent Laid-Open No. 5-288442 JP 2001-310429 A

  The object of the present invention is to have an adhesive strength between a foam sheet and a non-foamed resin layer that can withstand use at high temperatures, and it is difficult for foreign matter to be generated in the non-foamed resin layer, and it is excellent in appearance, lightness, design, and processability. Another object of the present invention is to provide a method for producing a polypropylene resin laminated foam sheet suitable for obtaining a molded article, the laminated foam sheet, and a molded article from the laminated foam sheet.

  That is, the present invention is a method for producing a polypropylene resin laminated foam sheet in which a polypropylene non-foamed resin layer is laminated on at least one side of a polypropylene resin foam sheet by extrusion lamination, and the resin temperature immediately after extrusion is 210 ° C. A method for producing a polypropylene resin laminated foam sheet, characterized in that a polypropylene non-foamed resin layer having a temperature of 250 ° C. or lower is laminated on the polypropylene resin foam sheet within 2 seconds (Claim 1). The method for producing a polypropylene resin laminated foam sheet according to claim 1, wherein the polypropylene resin laminated film is laminated on the polypropylene resin foam sheet through the non-foamed polypropylene resin layer (Claim 2), and extrusion lamination. The thickness of the non-foamed polypropylene resin layer is 20 to 15 The method for producing a polypropylene resin laminated foam sheet according to claim 1 or claim 2, wherein the polypropylene resin foam sheet has a density of 0.1 to 0.5 g / cc, The method for producing a polypropylene resin laminated foam sheet according to claim 1, 2 or 3, wherein the closed cell ratio is 60% or more and the number of cells in the thickness direction is 5 or more, and the polypropylene resin foam 3. The polypropylene resin according to claim 1, wherein the polypropylene resin as a base resin of the sheet is a modified polypropylene resin obtained by melt-kneading a polypropylene resin, isoprene and a radical initiator. A method for producing a laminated foam sheet (Claim 5), a polypropylene tree obtained by the production method according to Claims 1, 2, 3, 4 or 5. The present invention relates to a fat-laminated foam sheet (Claim 6) and a molded body (Claim 7) obtained by heat-molding the polypropylene resin laminated foam sheet according to Claim 6.

  By the present invention, there is sufficient adhesive strength between the foamed sheet and the non-foamed resin layer, it is difficult for foreign substances to be generated in the non-foamed resin layer, and the low-cost polypropylene-based resin laminated foam excellent in appearance, design, lightness, and workability. A sheet can be obtained.

  Embodiments of the present invention will be described with reference to FIG. 1, but the implementation of the present invention is not limited thereto.

  In the extrusion laminating apparatus of FIG. 1, 1: distance from foam sheet, 2: nip roll, 3: cooling roll, 4: T die, 5: foamed resin layer coming out of T die to pressure-bonded to foam sheet (hereinafter referred to as air) 6: Gap formed by nip roll 2 and cooling roll 3, 7: non-foamed resin layer, 8: laminated film, 9: roll for removing wrinkles of laminated film (hereinafter referred to as expander roll) 10: Indicates a laminated foam sheet.

  As a method for producing a laminated foam sheet composed of a polypropylene resin foam sheet and a non-foamed polypropylene resin layer, the foam sheet 1 is first fed into the gap 6 between the nip roll 2 and the cooling roll 3 along the nip roll 2, Take it along the cooling roll 3. At this time, after melting the non-foamed polypropylene resin in the extruder, the non-foamed resin layer 7 is extruded from the T die 4 into a film, and the non-foamed resin layer 7 and the foamed sheet 1 are pressure-bonded with the nip roll 2 and the cooling roll 3. The laminated foamed sheet 10 is obtained by taking up.

  As a method for producing a laminated foam sheet comprising a foam sheet, a non-foamed resin layer, and a laminated film, the foamed sheet 1 is fed between the nip roll 2 and the cooling roll 3 while keeping the foam sheet 1 along the nip roll 2 as described above. The non-foamed resin layer 7 is extruded from the T die 4 into a film shape, and the laminated film 8 is further fed through the expander roll 9 into the gap 6 between the nip roll 2 and the cooling roll 3. Then, the non-foamed resin layer 7 and the foamed sheet 1 are pressure-bonded and taken out to obtain a laminated foamed sheet 10 composed of the foamed sheet, the non-foamed resin layer, and the laminated film.

  In the present invention, the resin temperature of the non-foamed polypropylene resin layer immediately after being extruded from the T-die needs to be 210 ° C. or higher and 250 ° C. or lower. As a specific method for measuring the resin temperature, for example, using a non-contact temperature sensor (such as THERMO-HUNTER PT-3LF manufactured by Optex), the center of the non-foamed polypropylene resin layer extruded into a film from a T die The surface temperature of the part and the end can be measured to obtain the resin temperature of the polypropylene resin.

  When the resin temperature of the non-foamed polypropylene resin layer is less than 210 ° C, the adhesive strength between the foamed sheet and the non-foamed resin layer is weak, and sufficient adhesive strength with the foamed sheet to withstand use at high temperatures is obtained. May not be possible and is not preferred. On the other hand, when the resin temperature of the non-foamed polypropylene resin layer exceeds 250 ° C., foreign matter is generated due to thermal degradation of the resin, and a product free of foreign matter cannot be obtained, which is not preferable.

  In the present invention, the non-foamed polypropylene resin layer must be laminated to the polypropylene resin foam sheet within 2 seconds after being extruded from the T-die. If the time required for lamination to the foamed sheet exceeds 2 seconds, the foamed sheet and the non-foamed sheet are not even when the resin temperature of the non-foamed polypropylene resin layer immediately after being extruded from the T-die is adjusted to 210 ° C to 250 ° C. Adhesive strength with the foamed resin layer may not be sufficiently obtained, which is not preferable. The time from when the non-foamed polypropylene-based resin layer is extruded from the T-die to when the non-foamed polypropylene-based resin layer is laminated on the polypropylene-based resin foamed sheet is mainly the amount of resin discharged from the extruder, the take-up speed of the foamed sheet, and the air in FIG. The gap 5 can be adjusted. The time S until lamination on the foamed sheet can be obtained by the following equation.

S = Air gap / (Discharge rate / Non-foamed resin layer thickness × Non-foamed resin layer width) (1)
However, the unit of time S until lamination on the foam sheet is in seconds (s), and the discharge amount is a value obtained by dividing the amount of resin extruded in 1 second by the resin density of polypropylene 0.91 (g / cm ³ ). The unit is cm ³ / s. The unit of the air gap, the non-foamed resin layer thickness, and the non-foamed resin layer width is cm.

  Examples of the polypropylene resin constituting the non-foamed polypropylene resin layer include a propylene homopolymer, a block copolymer of propylene and another monomer, or a random polymer of propylene and another monomer. The polypropylene homopolymer is preferable from the viewpoint of high rigidity and low cost, and a block copolymer of the propylene and other monomers is preferable from the viewpoint of low temperature brittleness. When the polypropylene resin is a block copolymer of propylene and another monomer, or a random polymer of propylene and another monomer, the high crystallinity, high rigidity and 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 thickness of the non-foamed polypropylene resin layer is preferably 20 μm to 150 μm, more preferably 30 μm to 120 μm, and most 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 is thin. When the thickness of the non-foamed polypropylene resin layer exceeds 150 μm, the rigidity of the foamed sheet is improved, but the weight is increased and the cost is increased.

  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 melting and 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 melting and kneading a raw material polypropylene resin, an isoprene monomer, and a radical polymerization initiator is preferable in terms of easy production.

  As said raw material polypropylene-type resin, the thing similar to the polypropylene-type resin which comprises a non-foaming polypropylene-type resin layer can be used.

  In the raw material polypropylene resin, the other monomer copolymerizable with propylene is selected from the group of monomers consisting of ethylene, α-olefin, cyclic olefin, diene monomer and vinyl monomer. One or two or more selected monomers may be mentioned. 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 these other resins or rubbers added to the raw material polypropylene resin varies depending on the type of the resin or the type of rubber and may be within the range not impairing the effects of the present invention as described above. Usually, it is preferably about 25% by weight or less.

  The modified polypropylene resin may be produced by melt-kneading a polypropylene resin, an isoprene monomer, another vinyl monomer copolymerizable with the isoprene monomer, and a radical polymerization initiator.

  When isoprene monomer and other vinyl monomer copolymerizable with this isoprene monomer are used in combination, the amount of other vinyl monomer copolymerizable with isoprene monomer is The amount is preferably 100 parts by weight or less with respect to 100 parts by weight of the body, and more preferably 75 parts by weight or less on average. When the addition amount of the other vinyl monomer copolymerizable with the isoprene monomer exceeds the above range, the viscosity of the resulting modified polypropylene resin may be lowered, and foamability may be lowered.

  The addition amount of the isoprene monomer to be melt kneaded is preferably 0.1 to 20 parts by weight, more preferably 0.3 to 10 parts by weight with respect to 100 parts by weight of the raw material polypropylene resin. preferable. When the amount of the isoprene monomer is less than the above range, the foamability of the modified polypropylene resin may be lowered. On the other hand, when the amount exceeds the above range, the foamability is imparted to the polypropylene resin. The appearance of the foam sheet may be inferior.

  Examples of the radical polymerization initiator generally include peroxides and azo compounds. Examples of the radical polymerization initiator include one or more organic peroxides such as ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxydicarbonate, and peroxyester. can give. Of these, those having particularly high hydrogen abstraction ability are preferred.

  The addition amount of the radical polymerization initiator is within a range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the raw material polypropylene resin from the viewpoint of good foamability of the modified polypropylene resin and an economical viewpoint. It is preferable that it exists in the range of 0.2-5 weight part.

  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, etc., if necessary. Stabilizers or additives such as crosslinking agents, chain transfer agents, nucleating agents, lubricants, plasticizers, fillers, reinforcing materials, pigments, dyes, flame retardants, antistatic agents, and the like within a range that does not impair the effects of the present invention You may add in.

  The order and method of mixing and melt-kneading these raw material polypropylene resins, isoprene monomers, radical polymerization initiators and other added materials are not particularly limited. For example, raw material polypropylene resins, isoprene monomers , Radical polymerization initiator and other additive materials added as needed may be mixed and then melt-kneaded, or raw material polypropylene resin, radical polymerization initiator and other additive materials added as needed Isoprene monomer may be melt-kneaded after melt-kneading, or after obtaining a modified polypropylene resin by the above method, it may be melt-kneaded with additives and other resins added as necessary Good, and after modifying a part of the raw material polypropylene to make a master batch, the remaining raw material polypropylene tree And it may be melt-kneaded.

  The heating temperature at the time of melt-kneading varies depending on the type of resin, but it is usually 130 to 300 ° C. that the raw material polypropylene-based resin is sufficiently melted and does not thermally decompose to obtain sufficient foamability. It is preferable in that it can be performed. The time for melt kneading (the time after mixing the radical polymerization initiator and the isoprene monomer) is generally 30 seconds to 60 minutes.

  The melt kneading apparatus includes a kneader, a Banbury mixer, a Brabender, a single-screw extruder, a twin-screw extruder, etc., a two-axis surface renewal machine, a horizontal agitator such as a two-shaft multi-disc apparatus, or the like. Examples thereof include an apparatus capable of heating a polymer material such as a vertical stirrer such as a double helical ribbon stirrer to an appropriate temperature and kneading while applying an appropriate shear stress. Among these, a single-screw or twin-screw extruder is particularly preferable from the viewpoint of productivity. Moreover, in order to mix each material sufficiently uniformly, the melt kneading may be repeated a plurality of times.

  As described above, the modified polypropylene resin composition in the present invention can be obtained.

  Further, the foam sheet made of the polypropylene resin in the present invention is, for example, after melt-kneading the polypropylene resin and the foaming agent in the extruder, adjusting the foaming temperature in the extruder, and using a circular die having an annular lip, A cylindrical foam is obtained by extruding into the atmospheric pressure from the lip of the die, and then, after drawing and cooling the cylindrical foam, it is cut and opened after being drawn and cooled by a molding process using a cooling cylinder (mandrel). Manufactured easily by the 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 may be in the range of 0.5 to 10 parts by weight with respect to 100 parts by weight of the polypropylene resin composition. preferable.

  Moreover, in order to control the bubble diameter of a foam sheet to a suitable magnitude | size, you may use together nucleating agents, such as a sodium bicarbonate-citric acid mixture or a talc, as needed. 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.

  Further, in the production of the foam sheet, a thermoplastic resin may be mixed as long as the foamability of polypropylene is not impaired.

  In addition, the foamed sheet made of the polypropylene-based resin in the present invention may be stretched at the time of taking up to a mandrel for the purpose of obtaining a desired cell structure. .

  If necessary, the polypropylene resin of the present invention includes an antioxidant, a metal deactivator, a phosphorus processing stabilizer, an ultraviolet absorber, an ultraviolet stabilizer, a fluorescent brightener, a metal soap, an antacid adsorbent, etc. Stabilizers or additives such as crosslinking agents, chain transfer agents, nucleating agents, lubricants, plasticizers, fillers, reinforcing materials, pigments, dyes, flame retardants and antistatic agents may be added.

  The density of the foam sheet in the present invention is preferably 0.1 to 0.5 g / cc, and more preferably 0.13 to 0.5 g / cc. When it is smaller than 0.1 g / cc, the rigidity is lowered, and when it is larger than 0.5 g / cc, the heat insulating property is lowered.

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

  As for the thickness of the foam sheet which consists of polypropylene resin in this invention, 1-5 mm is preferable, More preferably, it is 1-3 mm. When the thickness is smaller than 1 mm, the heat insulating properties, rigidity, and buffering properties are lowered. When the thickness is larger than 5 mm, the moldability is lowered. The number of cells in the thickness direction is preferably 5 or more, more preferably 7 or more, and most preferably 16 or more. When it is smaller than 5, the heat insulating property and the surface property are lowered.

  In the method for producing a laminated foamed sheet comprising a foamed sheet, a non-foamed resin layer and a laminated film according to the present invention, the laminated film used is made of a polypropylene resin such as polypropylene homopolymer or polypropylene copolymer, and is not stretched or 2 This is an axially stretched polypropylene film. The laminated film may be a multilayer film having two or more layers.

  The thickness of the polypropylene resin laminated film is preferably 15 to 80 μm, more preferably 20 to 70 μm, and most preferably 25 to 60 μm. When the thickness 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 is lowered. When the thickness exceeds 80 μm, the rigidity is improved, but the lightweight property of the laminated foam sheet is lowered.

  The peel strength of the polypropylene resin foam sheet and the polypropylene resin laminate film of the polypropylene resin laminate foam sheet of the present invention is preferably 1.5 N / 25 mm or more. When the peel strength is less than 1.5 N / 25 mm, the film layer may swell during molding and heating of the obtained laminated foam sheet, and a good molded product may not be obtained.

  Moreover, since the polypropylene resin laminated foam sheet of this invention provides designability, a printing layer can be formed and laminated | stacked on the surface adhere | attached with the non-foamed resin layer of a polypropylene resin laminated film.

  Printing is performed 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 rubber, chlorinated polypropylene, polymerized acrylic acid and its derivatives, condensates of dimer acid and polyamine, polyester or polyether Examples thereof include a polymer of diisocyanate and a cell source nitrate ester compound. 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.

  Moreover, in order to improve the adhesiveness of a printing layer and a foam sheet, an anchor coating agent can be used. 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 of the present invention is formed by a known method such as gravure printing. The pattern of printing is not particularly limited, and a laminated foam sheet and a laminated foam having gloss and excellent design are obtained by disposing the printed layer on the inner surface (the foamed layer side of the polypropylene resin layer).

  Since the polypropylene resin foam sheet laminate in the present invention is excellent in heat moldability such as plug molding, vacuum molding, and pressure molding, it is possible to obtain a molded article having a small thickness unevenness and a beautiful appearance.

The basis weight of the laminated foamed sheet produced in the present invention is 0.23 kg / m for any of the laminated foamed sheet composed of the foamed sheet and the non-foamed resin layer, the laminated foamed sheet composed of the foamed sheet, the non-foamed resin layer, and the laminated film. ^{2 ~0.5kg} / m ² is more preferably preferably ^{0.27kg / m 2 ~0.45kg / m 2} , 0.29kg / m 2 ~0.4kg / m 2 is most preferred. If the basis weight is smaller than 0.23 kg / m ² , it is not preferable because sufficient rigidity cannot be obtained. If the basis weight exceeds 0.5 kg / m ² , sufficient rigidity can be obtained, but the lightness is reduced and the cost is increased.

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

Next, the present invention will be described in detail based on examples, but the present invention is not limited to such examples.
(Measurement of density of foam sheet) Measured according to JIS-K6767.
(Measurement of closed cell ratio of foamed sheet) Measurement was performed by an air pycnometer according to the method described in ASTM D2856.
(Measurement of thickness of foam sheet) After measuring points at 30 mm intervals in the width direction of the foam sheet and 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 Was the thickness of the foam sheet.
(Measurement of the number of cells in the thickness direction of the foamed sheet) Ten measurement points are 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 is measured using a loupe (pecker / microx10 manufactured by Peacock). Measured. Then, the average of the measured value of each point was made into the number of cells of the thickness direction.
(Peeling strength of the laminated foam sheet) The peel strength of the laminated film and the foamed layer of the obtained laminated foam sheet was measured according to JIS Z0230. In the measurement, a test piece having a width of 25 mm was cut out from the laminated foamed sheet, and 180 ° peeling was performed at a peeling speed of 100 mm / min.
(Adhesive evaluation of laminated foam sheet) The obtained laminated foam sheet was cut into a 540 × 540 mm square, fixed to a frame having an inner dimension of 500 × 500 mm, and then inserted into a heating furnace adjusted to an atmospheric temperature of 200 ° C. for 55 seconds. It was taken out later. The obtained non-foamed resin layer or laminated film layer of the laminated foam sheet after heating was observed and evaluated according to the following criteria.
○: No swelling of the non-foamed resin layer or the laminated film is observed.
X: Swelling of the non-foamed resin layer or the laminated film is observed.
(Appearance Evaluation of Laminated Foamed Sheet) The surface of the obtained laminated foamed sheet on the non-foamed resin layer side or the laminated film side was visually observed.
○: There is no foreign matter on the film surface, and it is glossy.
X: Foreign matter is present on the film surface or there is no gloss.
(Rigidity evaluation of molded body) The rigidity evaluation of the molded body was performed by molding the molded body having a dimension inside the opening formed from the obtained laminated foamed sheet of 185 mm × 205 mm and a depth of 30 mm (the molded body is a non-foamed resin layer or a laminated layer) Using a DIGITAL FORCE GAUGE (MODEL No. MD-2000 (SV-2)) manufactured by IMADA, the center of the lip at the longitudinal side of the molded body is 205 mm. And compressing at a compression rate of 10 mm / second so that the dimension is compressed in the direction of 185 mm, and measuring the load when compressed by 10 mm, the load (N) is the basis weight of the laminated foam sheet (kg / m ² The value divided by) was taken as the rigidity value of the molded body.
○: Stiffness value of the molded body is 20 N · m ² / kg or more ×: Stiffness value of the molded body is less than 20 N · m ² / kg The following shows the manufacturing method and the laminating method of the foam sheets used in Examples and Comparative Examples .
(Manufacturing method of foam sheet A) 100 parts by weight of homopolypropylene (G103 manufactured by Grand Polymer Co., Ltd.) and 0.35 parts by weight of a radical polymerization initiator (t-butylperoxybenzoate) were stirred and mixed in a ribbon blender. The modified polypropylene is supplied to the twin screw extruder by a feeder, 0.5 parts by weight of isoprene is supplied from the middle of the extruder using a liquid pump, melt kneaded and melt extruded in the twin screw extruder. A pellet of the resin resin composition was obtained.

  The twin-screw extruder was the same-direction twin-screw type, the screw diameter was 44 mmφ, and the maximum screw effective length (L / D) was 38. The set temperature of the cylinder part of this twin-screw extruder was set to 180 ° C. until isoprene monomer injection, 200 ° C. after isoprene injection, and the screw rotation speed was set to 140 rpm.

A composition in which 100 parts by weight of the modified polypropylene resin composition, 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.) are stirred and mixed with a ribbon blender. After supplying to a 90-125 mmφ tandem type extruder and melting in a first stage extruder (90 mmφ) set at 200 ° C., isobutane as a foaming agent was added to 100 parts by weight of the modified polypropylene resin composition. 1.7 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 at atmospheric pressure from a circular die (127 mmφ) To form a cylindrical foam by drawing and cooling at 4.4 m / min while being molded in a cooling cylinder having an outer diameter of 335 mm and a body length of 800 mm. To obtain a foamed sheet of 1035mm width by cutting open it with a cutter. The obtained foamed sheet had a density of 0.14 g / cc, a closed cell ratio of 72%, an average thickness of 1.9 mm, and a cell number of 8.1 pieces / thickness.
(Manufacturing method of foam sheet B) 100 parts by weight of polypropylene resin (PF-814 manufactured by Sun Allomer Co., Ltd.), 0.05 parts by weight of blend oil, 0.7 part by weight of cell nucleating agent (Selfon SC / K manufactured by Eiwa Kogyo Co., Ltd.) Was mixed in a ribbon blender and fed to a 90-125 mmφ tandem extruder and melted in a first stage extruder (90 mmφ) set at 200 ° C. 1.5 parts by weight of 100 parts by weight of a high-quality polypropylene-based resin composition, mixed in, cooled in a second stage extruder (125 mmφ) set at 165 ° C., and discharged from a 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, drawing and cooling at 4.6 m / min to obtain a cylindrical foam. To obtain a foamed sheet of 1035mm width by cutting open in ter. The obtained foamed sheet had a density of 0.147 g / cc, a closed cell ratio of 82%, an average thickness of 1.8 mm, and a number of cells of 9.2 / thickness.
(Extrusion Laminating Method) Using the extrusion laminating equipment shown in FIG. 1, the foamed sheet 1 shown in Table 1 is fed out, the non-foamed resin layer 7 shown in Table 1 is extruded from the T-die 4 into a film, and the roll 2 and the cooling roll Then, the laminated foamed sheet was produced. Further, when a laminated film is used, the laminated film 8 is passed between the roll 2 and the cooling roll 3 through the expander roll 9, and the laminated film 8, the non-foamed resin layer 7, and the foamed sheet are rolled by the roll 2 and the cooling roll 3. A laminated foamed sheet made of a foamed sheet, a non-foamed resin layer, and a laminated film was produced by pressure bonding and taking 1 out. Here, the time until the non-foamed resin layer was laminated on the foamed sheet was calculated from the formula (1).
(Non-foamed resin layer C) Homopolypropylene CS3230 manufactured by Chisso Corporation was used as the non-foamed resin layer.
(Non-foamed resin layer D) Homopolypropylene J103WB manufactured by Grand Polymer Co., Ltd. was used as the non-foamed resin layer.
(Non-foamed resin layer E) Block polypropylene J703W manufactured by Grand Polymer Co., Ltd. was used as the non-foamed resin layer.
(Laminated film F) manufactured by Tonen Co., Ltd., unstretched polypropylene film with a thickness of 25 μm, Polyace “2
5H "was used as the laminated film. In addition, the printing layer was given to the surface adhere | attached with a non-foaming resin layer by the gravure method.
(Laminated film G) Santox Co., Ltd., 30 μm thick biaxially stretched polypropylene film, “M
F20 "was used as the laminated film. In addition, the printing layer was given to the surface adhere | attached with a non-foaming resin layer by the gravure method.
Example 1 A non-foamed resin layer C was laminated on the foamed sheet A by the extrusion laminating method under the conditions shown in Table 1 to obtain a laminated foamed sheet.
Example 2 A laminated foamed sheet was obtained in the same manner as in Example 1 except that the non-foamed resin layer was E.
(Example 3) A non-foamed resin layer D and a laminated film F were laminated on the foamed sheet A by the extrusion laminating method under the conditions shown in Table 1 to obtain a laminated foamed sheet.
(Example 4) A laminated foam sheet was obtained in the same manner as in Example 3 except that the laminated film was G.
(Example 5) A laminated foam sheet was obtained in the same manner as in Example 1 except that the foam sheet was changed to B.
(Comparative Example 1) A laminated foam sheet was obtained in the same manner as in Example 1 except that the conditions for extrusion lamination were as shown in Table 1.
(Comparative Example 2) A laminated foam sheet was obtained in the same manner as in Example 1 except that the conditions for extrusion lamination were as shown in Table 1.
(Comparative Example 3) A laminated foamed sheet was obtained in the same manner as in Example 3 except that the conditions for extrusion lamination were as shown in Table 1.

  Table 1 shows the evaluation results of the laminated foam sheets in Examples and Comparative Examples.

  As described above, by producing a laminated foamed sheet under the extrusion lamination conditions as in Examples 1 to 5, the film does not peel off during thermoforming, and there is no foreign matter in the non-foamed resin layer. It can be seen that a good molded article can be obtained. On the other hand, in Comparative Examples 1 and 2, the phenomenon that the film layer peels off from the foamed sheet at the time of heat molding is observed. In Comparative Example 3, although there is no peeling of the film layer at the time of heat molding, foreign matter is generated at the time of extrusion lamination and cannot be obtained as a product.

  The polypropylene resin laminated foam sheet produced by the present invention is superior in heat resistance and oil resistance because the base resin is a polypropylene resin, and is excellent in heat insulation and light weight by providing a foam layer. Is.

  From the above, the polypropylene-based resin laminated foam sheet of the present invention is beautiful in appearance, excellent in heat resistance, oil resistance, light weight, and heat insulation, for cooking using a microwave oven, or for reheating a microwave oven It is suitable as a food container.

It is a figure which shows an example of the extrusion laminating method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Foam sheet 2 Nip roll 3 Cooling roll 4 T die 5 Air gap 6 The clearance gap formed by the nip roll 2 and the cooling roll 3 7 Non-foamed resin layer 8 Laminated film 9 Expander roll 10 Laminated foam sheet

Claims (7)

A method for producing a polypropylene resin laminated foam sheet in which a non-foamed polypropylene resin layer is laminated on at least one surface of a polypropylene resin foam sheet by extrusion lamination, and a resin temperature immediately after extrusion is 210 ° C. or higher and 250 ° C. or lower. A non-foamed polypropylene-based resin layer is laminated on a polypropylene-based resin foamed sheet within 2 seconds. The method for producing a polypropylene resin laminated foam sheet according to claim 1, wherein the polypropylene resin laminated film is laminated on the polypropylene resin foam sheet through a non-foamed polypropylene resin layer formed by extrusion lamination. The method for producing a polypropylene resin laminated foam sheet according to claim 1 or 2, wherein the non-foamed polypropylene resin layer formed by extrusion lamination has a thickness of 20 to 150 µm. The polypropylene resin foam sheet has a thickness of 1 to 5 mm, a density of 0.1 to 0.5 g / cc, a closed cell ratio of 60% or more, and a number of cells in the thickness direction of 5 or more. Or the manufacturing method of the polypropylene resin laminated foam sheet of 3. 3. The polypropylene resin, which is a base resin of the polypropylene resin foam sheet, is a modified polypropylene resin obtained by melt-kneading a polypropylene resin, isoprene, and a radical initiator. Manufacturing method of polypropylene resin laminated foam sheet. A polypropylene-based resin laminated foam sheet obtained by the production method according to claim 1, 2, 3, 4 or 5. The molded object obtained by heat-molding the polypropylene resin laminated foam sheet of Claim 6.

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