JP2006130814A - Laminated foamed polypropylene resin sheet and its molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated foamed polypropylene resin sheet which does not spoil thermal insulation properties, oil resistance, and heat resistance, is excellent in appearance and designability, and has a small environmental load in its production process. <P>SOLUTION: In the laminated foamed sheet 10, a polypropylene resin film 8 is laminated on at least one side of a foamed polypropylene resin sheet 1 by extrusion lamination. By applying printing on one side of the film by using a water base ink, the laminated foamed polypropylene resin sheet having the above characteristics can be obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polypropylene resin laminated foam sheet and a molded product 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 using polypropylene resin as the base resin is superior in heat resistance and oil resistance compared to the conventional polystyrene resin foam sheet due to the characteristics of the base resin, so it can be used at convenience stores and supermarkets. It is suitable for use in food containers such as lunch boxes sold.

  In addition, a polypropylene resin laminated foam sheet obtained by laminating a polypropylene resin film on the foam sheet can improve rigidity and moldability. Therefore, a non-foamed resin layer or a film layer can be thermally laminated on a polypropylene resin foam sheet. A method of laminating (Patent Document 1) is disclosed.

Furthermore, the polypropylene-based resin laminated foam sheet can be made excellent in appearance and design when made into a food container by printing on a film. Ink used for such printing is generally In order to disperse pigments and resins, organic solvents such as toluene and methyl ethyl ketone are included, and these organic solvents are generated as vapors in the drying process. There is a problem of requiring capital investment.
Japanese Patent No. 3140847

  An object of the present invention is to provide a polypropylene resin laminated foam sheet that does not impair the heat insulation, oil resistance, and heat resistance inherent to the polypropylene resin foam sheet, and that is excellent in appearance and design and has a low environmental impact in the manufacturing process. There is to do.

As a result of intensive studies to solve such problems, the present inventors have reached the present invention.
That is, the present invention
A polypropylene resin laminated foam sheet in which a polypropylene resin film is laminated on at least one side of a polypropylene resin foam sheet by extrusion lamination, and the polypropylene resin film is printed on one side using water-based ink -Based resin laminated foam sheet (Claim 1),
The polypropylene-based resin laminated foam sheet (claim 2) and claim 1 or claim 2, wherein the water-based ink comprises water and alcohol as a base material, and a pigment and a resin component are dispersed in the base material. A molded product obtained by thermoforming the polypropylene resin laminated foam sheet according to claim 2 (Claim 3).
About.

  According to the present invention, it is possible to obtain a polypropylene-based resin laminated foam sheet that is excellent in appearance and design, and has a small environmental load in the production process, without impairing heat insulation, oil resistance, and heat resistance.

  An embodiment of the present invention will be described with reference to FIG. 1, but the implementation of the present invention is not limited to this.

  The laminated film used in the method for producing a laminated foamed sheet comprising a foamed sheet, a non-foamed resin layer and a laminated film of the present invention comprises a polypropylene resin such as a polypropylene homopolymer or a polypropylene copolymer, and is unstretched or biaxial. It is a stretched polypropylene film. The laminated film may be a multilayer film having two or more layers.

  The polypropylene resin film used in the present invention is printed on one side with water-based ink.

  As the water-based ink, an ink having water and alcohol as a base material in which a pigment and a resin component are dispersed in the base material is preferably used.

  Preferable specific examples of the alcohol constituting the water-based ink include isopropanol, ethyl alcohol, methanol, and propanol. These may be used alone or in combination of two or more.

  The resin component constituting the water-based ink exhibits the effect of dissolving in the base material and dispersing the pigment. Examples of preferable use include, for example, a copolymer of vinyl chloride and vinyl acetate, a chlorinated product of rubber, and a polypropylene. Examples thereof include chlorinated products, polymers of acrylic acid and derivatives thereof, condensates of dimer acid and polyamine, polymers of polyester or polyether and diisocyanate, and cellulose nitrate compounds.

  By using a film printed with a water-based ink using water and alcohol as a base material, a process for producing a polypropylene-based resin foam laminate sheet by an extrusion laminating method described later (through a molten polypropylene-based non-foamed resin) Laminate polypropylene resin foam sheets), reducing the amount of solvent components that have been evaporated and volatilized in films printed with conventional solvent-based inks that use organic solvents such as toluene and methyl ethyl ketone as the base material. The load of can be reduced.

  The polypropylene resin film used in the present invention may be one in which an anchor coating agent is further applied on the ink for the purpose of improving the adhesion between the printed layer and the foamed sheet. As an example of an anchor coating agent that is preferably used, a chlorinated polypropylene dispersed in water can be exemplified.

  The thickness of the polypropylene resin film used in the present invention is 10 to 80 μm, preferably 15 to 70 μm. When the thickness of the polypropylene resin film is less than 10 μm, the film may be broken due to stretching at the time of heat molding of the obtained laminated foamed sheet, and the moldability tends to be inferior. When thickness exceeds 80 micrometers, there exists a tendency for it to be inferior in terms of lightweight and cost.

  In addition, the polypropylene resin film may be subjected to corona treatment or plasma treatment on the printing surface in advance for the purpose of improving the adhesion with ink.

  The printing is performed by a known method such as gravure printing. The printing pattern is not particularly limited, and a laminated foam sheet having excellent appearance and design and having a small environmental load can be obtained by arranging the printed layer on the inner surface (the foamed layer side of the polypropylene resin layer).

  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 FIG.

  The production of the polypropylene resin laminated foam sheet of the present invention can be carried out using an extrusion laminating apparatus schematically shown in FIG.

  As a method for producing the polypropylene resin laminated foam sheet of the present invention by the extrusion laminating method, the foamed sheet 1 is fed between the nip roll 2 and the cooling roll 3 along the nip roll 2, and the polypropylene resin is drawn from the T die 4. The non-foamed resin layer 7 is extruded into a film shape, and the film 8 is further passed through an expander roll (roll for removing wrinkles of the film) 9 so that the printing surface of the film 8 becomes the non-foamed resin layer 7 side and cooling. The laminated foam sheet 10 of the present invention is obtained by feeding the gap 8 between the roll 3 and the film 8, the non-foamed resin layer 7, and the foamed sheet 1 with the nip roll 2 and the cooling roll 3.

  At this time, the resin temperature of the non-foamed resin layer immediately after being extruded from the T die is preferably 210 to 250 ° C. 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. It may not be possible. On the other hand, when the resin temperature of the non-foamed polypropylene resin layer exceeds 250 ° C., foreign matter tends to be easily generated due to thermal degradation of the resin.

  In addition, as a specific method for measuring the resin temperature, for example, a non-foamed polypropylene resin layer extruded from a T die into a film using a non-contact temperature sensor (such as THERMO-HUNTER PT-3LF manufactured by Optics). The surface temperature of the center part and the end part of the resin can be measured to obtain the resin temperature of the polypropylene resin.

  In the present invention, the polypropylene resin non-foamed resin layer 8 is preferably laminated on the polypropylene resin foam sheet 1 within 2 seconds after being extruded from the T-die 4. When the time S from when the polypropylene-based resin non-foamed resin layer 8 is extruded from the T-die 4 to when it is laminated on the polypropylene-based resin foamed sheet 1 exceeds 2 seconds, the polypropylene immediately after being extruded from the T-die Even if the resin temperature of the resin non-foamed resin layer is adjusted to 210 ° C. to 250 ° C., sufficient adhesion between the foamed sheet and the non-foamed resin layer may not be obtained.

The time S from when the polypropylene-based resin non-foamed resin layer 8 is extruded from the T-die 4 to when it is laminated on the polypropylene-based resin foamed sheet 1 is mainly the amount of resin discharged from the extruder, the take-up speed of the foamed sheet, and 1 can be adjusted by the air gap 5 (distance until the non-foamed resin layer 8 coming out of the T-die 4 is pressure-bonded to the foamed sheet 1) 5. The time S required to laminate 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 to be laminated on the foam sheet 1 is seconds (s), and the discharge amount is a value obtained by dividing the amount of resin extruded per second by polypropylene resin density 0.91 (g / cm ³ ). Yes, 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.

The basis weight of the polypropylene resin laminated foam sheet of the present invention thus obtained is 0.20 to 0.5 kg / m ² , preferably 0.22 to 0.45 kg / m ² . If the basis weight of the polypropylene resin laminated foam sheet is less than 0.20 kg / m ² , there is a tendency that sufficient rigidity cannot be obtained. If the basis weight exceeds 0.5 kg / m ² , the rigidity can be sufficiently obtained, but the light weight and the cost tend to be inferior.

  Examples of the polypropylene resin constituting the polypropylene resin non-foamed resin layer include a propylene homopolymer, a block copolymer of propylene and another monomer, or a random polymer of propylene and another monomer. However, the polypropylene homopolymer is preferable from the viewpoint of high rigidity and low cost, and the block copolymer of 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, 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 polypropylene resin non-foamed resin layer of the present invention, not only a polypropylene resin can be used alone, 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 polypropylene resin non-foamed resin layer in the present invention is 20 μm to 150 μm, preferably 30 μm to 120 μm, and 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 appearance of the foamed sheet tends to be impaired. When the thickness of the non-foamed polypropylene resin layer exceeds 150 μm, it is not preferable in terms of light weight and cost.

  The polypropylene resin foam sheet used in the present invention is a long chain branch by irradiating a linear polypropylene resin (hereinafter, this polypropylene resin may be referred to as “raw polypropylene resin”) with an electron beam. Or a modified polypropylene resin obtained by melting and kneading a raw material polypropylene resin, an isoprene monomer and a radical polymerization initiator (for example, HMS-PP manufactured by Sun Allomer Co., Ltd.) What was used as base resin is used preferably.

  In particular, when a base material is a modified polypropylene resin obtained by melting and kneading a raw material polypropylene resin, an isoprene monomer and a radical polymerization initiator, a foamed sheet having closed cells and excellent in moldability and heat insulating properties can be easily obtained. Obtainable.

  As said raw material polypropylene-type resin, the thing similar to the polypropylene-type resin which comprises a polypropylene-type non-foamed 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. And at least one 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 these other resins or rubbers added to the raw material polypropylene-based resin varies depending on the type of other 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 and a radical polymerization initiator, and if necessary, another vinyl monomer copolymerizable with the isoprene monomer. Good.

  Specific examples of other vinyl monomers copolymerizable with the isoprene monomer include acrylic resins such as styrene, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, methyl acrylate, ethyl acrylate, and butyl acrylate. Examples thereof include acid esters, methacrylic acid esters such as methyl methacrylate, ethyl methacrylate and butyl methacrylate, acrylonitrile, divinylbenzene and butadiene.

  When an isoprene monomer and another vinyl monomer copolymerizable with this isoprene monomer are used in combination, the addition amount of the other vinyl monomer copolymerizable with the isoprene monomer is The amount is preferably 100 parts by weight or less with respect to 100 parts by weight, 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 100 parts by weight, the viscosity of the resulting modified polypropylene resin is remarkably lowered, and the 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 added is less than 0.1 parts by weight, the foamability of the modified polypropylene resin may be reduced. On the other hand, when the amount exceeds 20 parts by weight, the polypropylene resin has foamability. Although it is provided, the appearance of the foamed 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 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 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, the raw material polypropylene resin, the isoprene monomer, the radical polymerization initiator and other additive materials added as necessary may be mixed and then melt-kneaded, or the raw material polypropylene resin, the radical polymerization initiator and Isoprene monomer may be melt-kneaded after melt-kneading other additive materials added as necessary, or after adding a modified polypropylene resin by the above method, addition added as needed It may be melt-kneaded with an agent or other resin, or may be melt-kneaded with the remaining raw material polypropylene-based resin after a part of the raw material polypropylene is modified into a master batch.

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

  Examples of the melt-kneading apparatus include a kneader, a Banbury mixer, a Brabender, a single-screw extruder, a twin-screw extruder and other horizontal mixers, a two-axis surface renewal machine, a two-shaft multi-disc apparatus and the like, or Examples thereof include an apparatus capable of kneading while heating a polymer material to an appropriate temperature and applying an appropriate shear stress, such as a vertical stirrer such as a double helical ribbon stirrer. 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.

  The polypropylene resin foam sheet in the present invention is prepared by, for example, melt-kneading a polypropylene resin and a foaming agent in an extruder, adjusting the foaming temperature in the extruder, and using a circular die having an annular lip. Easily obtained by extruding into atmospheric pressure to obtain a cylindrical foam, and then drawing and removing the cylindrical foam by a cooling cylinder (mandrel), and after stretching and cooling, the sheet is cut open. Manufactured. 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. These may be used alone or in combination of two or more.

  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 polypropylene resin foam sheet in the present invention may be accelerated at the time of taking up to a mandrel, for example, by extruding and foaming to promote cooling for the purpose of obtaining a desired cell structure.

  The polypropylene resin for obtaining the foamed 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, and a metal soap. Add additives such as stabilizers such as antacid adsorbents, or crosslinking agents, chain transfer agents, nucleating agents, lubricants, plasticizers, fillers, reinforcing materials, pigments, dyes, flame retardants, antistatic agents, etc. May be.

  The density of the polypropylene resin foam sheet in the present invention is preferably 0.05 to 0.5 g / cc, and more preferably 0.06 to 0.5 g / cc. When the density of the polypropylene resin foam sheet is less than 0.05 g / cc, the rigidity tends to be insufficient, and when it is greater than 0.5 g / cc, the heat insulation tends to be inferior.

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

  The thickness of the polypropylene resin foam sheet in the present invention is 1 to 7 mm, more preferably 1 to 5 mm. When the thickness of the polypropylene resin foam sheet is smaller than 1 mm, the heat insulating properties and rigidity tend to be insufficient, and when the thickness is larger than 7 mm, the moldability tends to be inferior.

  In the present invention, the number of cells in the thickness direction of the polypropylene resin foam sheet is preferably 5 or more, more preferably 7 or more, and even more preferably 9 or more. When the number of cells in the thickness direction of the polypropylene resin foam sheet is smaller than 5, the heat insulating property and the surface property tend to be inferior.

  The polypropylene resin laminated foam sheet in the present invention can be easily formed into a molded body such as a cup, a tray, or a bowl by thermoforming.

  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.

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

(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.

(Adhesive evaluation of laminated foam sheet)
The obtained laminated foamed sheet was cut into a 540 × 540 mm square, fixed to a frame having an inner dimension of 500 × 500 mm, inserted into a heating furnace adjusted to an atmospheric temperature of 200 ° C. for 55 seconds, and then taken out. 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.

(Evaluation of oil resistance and heat resistance of molded products)
The obtained molded article was immersed in 500 ml of salad oil and then heated in a microwave oven (500 W) for 180 seconds. After heating, the salad oil was taken out and the inside of the container was evaluated according to the following criteria.
○: No film lift is observed.
X: The film float is seen in part (peeling from the foam sheet).

(Environmental impact assessment when manufacturing laminated foam sheets)
As a degree of environmental load in the manufacturing process of the laminated foam sheet, a simple gas sensor (manufactured by Shin Cosmos Electric Co., Ltd., XP-) is used to detect the odor generated when the printed polypropylene film and the molten polypropylene resin contact. 329). The measurement was performed for 5 minutes around the roll 2 and the cooling roll 3 shown in FIG. 1, and the maximum value in 5 minutes was taken as a measurement value and evaluated according to the following criteria.
○: Measurement value is less than 1000 ×: Measurement value is 1000 or more

(Method for producing polypropylene resin foam sheet A)
A blend obtained by stirring and mixing 100 parts by weight of homopolypropylene (Grand Polymer Co., Ltd., J103WB) and 0.35 parts by weight of a radical polymerization initiator (t-butylperoxybenzoate) with a ribbon blender was added to a twin screw extruder with a measuring feeder. Then, 0.5 parts by weight of isoprene is supplied from the middle of the extruder using a liquid pump, melt-kneaded in the twin-screw extruder, and melt-extruded to obtain pellets of the modified polypropylene resin composition. 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.

  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 (manufactured by Eiwa Kogyo Co., Ltd., Cellbon SC / K) are mixed by stirring with a ribbon blender. Was supplied to a 90-125 mmφ tandem type extruder and melted in a first stage extruder (90 mmφ) set at 200 ° C., and then isobutane was added as a foaming agent to 100 parts by weight of the modified polypropylene resin composition. In contrast, 3.2 parts by weight was injected and mixed, cooled in a second-stage extruder (125 mmφ) set at 160 ° C. (measured by a temperature sensor installed in the resin inflow part of the die), and atmospheric pressure from a circular die (127 mmφ) Ejected downward, drawn and cooled at 4.4 m / min while being molded in a cooling cylinder with an outer diameter of 335 mm and body length of 800 mm. Give the body, by opening up this with a cutter to obtain a foamed sheet of 1035mm wide. The obtained foamed sheet had a density of 0.09 g / cc, a closed cell ratio of 72%, an average thickness of 3.1 mm, and a number of cells of 9.1 cells / thickness.

(Method for producing polypropylene resin foam sheet B)
100 parts by weight of a polypropylene resin (manufactured by Sun Allomer, PF-814), 0.05 part by weight of blend oil and 0.7 part by weight of a cell nucleating agent (manufactured by Eiwa Kogyo Co., Ltd., Cellbon SC / K) are stirred with a ribbon blender. The mixed compound is supplied to a 90-125 mmφ tandem type extruder, melted in a first stage extruder (90 mmφ) set at 200 ° C., and then the modified polypropylene resin composition containing isobutane as a foaming agent. 1.5 parts by weight of 100 parts by weight is injected and mixed, cooled in a second-stage extruder (125 mmφ) set at 165 ° C., and discharged from a circular die (127 mmφ) under atmospheric pressure. Stretching and cooling while pulling at 4.6 m / min while forming with a 800 mm long cooling cylinder to obtain a cylindrical foam, which is cut with a cutter To obtain a foamed sheet of 1035mm wide by. 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 cell number of 9.2 / thickness.

(Extrusion lamination method)
Using the extrusion laminating apparatus shown in FIG. 1, the foam sheet 1 shown in Table 1 is fed out, the non-foamed resin layer 7 is extruded into a film form from the T-die 4, and the printed film 8 is rolled through the expander roll 9. 2 and the cooling roll 3, and the film 8, the non-foamed resin layer 7, and the foamed sheet 1 are pressure-bonded and taken up by the roll 2 and the cooling roll 3 to laminate the foamed sheet and the non-foamed resin layer. A laminated foam sheet made of a film was produced.

(Non-foamed resin layer C)
Homopolypropylene (manufactured by Chisso Corporation, CS3230) was used as the non-foamed resin layer.

(Film D)
A biaxially stretched polypropylene film (manufactured by Santox Co., Ltd., PA20W) having a thickness of 20 μm was used as the film. In addition, the surface adhering to the non-foamed resin layer was subjected to woodgrain printing by a gravure method using water-based ink (LAMITEC) manufactured by Tokyo Ink Co., Ltd.

(Film E)
A biaxially stretched polypropylene film (manufactured by Santox Co., Ltd., PA20) having a thickness of 20 μm was used as the film. In addition, the surface adhering to the non-foamed resin layer was printed with a grain tone by gravure method using ink manufactured by Dainichi Seika Co., Ltd. (Paramic 21, using toluene and methyl ethyl ketone as a base material).

(Film F)
A biaxially stretched polypropylene film (manufactured by Santox Co., Ltd., PA20) having a thickness of 20 μm was used as the film. The surface to be bonded to the non-foamed resin layer was printed with a grain tone by a gravure method using ink (Hilamic, using toluene and methyl ethyl ketone as a base material) manufactured by Dainichi Seika Co., Ltd.

Example 1
With respect to the foam sheet A, a non-foam resin layer temperature is 235 ° C., an air gap is 10 cm, and a time period until the non-foam resin layer is laminated to the foam sheet is 1.7 seconds by an extrusion laminating method. C and film D were laminated to obtain a laminated foam sheet having a basis weight of 0.35 kg / m ² . Here, the thickness of the non-foamed resin layer was 40 μm.
The obtained laminated foamed sheet was molded using a single foam molding machine (VAS-66-45T manufactured by Toko Co., Ltd.), and then the periphery of the opening was punched out to obtain a molded product of the laminated foamed sheet. As the molding die, a square-shaped container having a container size of 210 mm × 180 mm × H30 mm is used. For molding, matched mold molding using a top mold as a female mold and a bottom mold as a male mold (mold clearance 1.5 mm) ) So that the inner surface of the container became a film. At this time, the foamed sheet surface temperature immediately before molding was 150 ± 5 ° C. over the entire surface, and the mold temperature was maintained at 50 ° C. for molding. Table 1 shows the evaluation results of the obtained laminated foam sheet and molded product.

(Example 2)
A laminated foam sheet was obtained in the same manner as in Example 1 except that foam sheet B was used instead of foam sheet A. Table 1 shows the evaluation results of the obtained laminated foam sheet and molded product.

(Comparative Example 1)
A laminated foam sheet was obtained in the same manner as in Example 1 except that the film E was used instead of the film D. Table 1 shows the evaluation results of the obtained laminated foam sheet and molded product.

(Comparative Example 2)
A laminated foam sheet was obtained in the same manner as in Example 1 except that the film F was used instead of the film D. Table 1 shows the evaluation results of the obtained laminated foam sheet and molded product.

  As described above, as in Examples 1 and 2, the polypropylene-based resin laminated foam sheet using water-based ink for printing is a conventionally used polypropylene-based resin laminated foam using ink using toluene or methyl ethyl ketone. Similar to the sheet, the film has good adhesion, and the molded body produced using the laminated foam sheet does not float on the container surface even when heated with oil in it. It can be suitably used, and it can be further seen that the environmental load can be reduced.

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 (3)

  A polypropylene resin laminate foam sheet in which a polypropylene resin film is laminated by extrusion lamination on at least one side of a polypropylene resin foam sheet, and printing is performed using water-based ink on one side of the polypropylene resin film. Polypropylene resin laminated foam sheet.   The polypropylene resin laminated foam sheet according to claim 1, wherein the water-based ink has water and alcohol as a base material, and a pigment and a resin component are dispersed in the base material.   A molded article obtained by thermoforming the polypropylene resin laminated foam sheet according to claim 1 or 2.

Images