JPH11322993A - Polypropylene resin crosslinking foamed sheet and preparation of laminated foamed particle molding of foamed sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a polypropylene resin crosslinking foamed sheet maintaining sufficient buffer properties without being crushed or torn and having good adhesive processability with the other composite materials even when the sheet is subjected to hard fabrication, and to provide a preparation method of a laminated foamed particle molding using the foamed sheet by a skinmold molding method. SOLUTION: This polypropylene resin crosslinking foamed sheet is a foamed sheet using a polypropylene resin as a base resin, the storage modulus of the foamed sheet in a tensile measure is 3×10<7> -3×10<8> dyn/cm<2> at 50 deg.C, 1×10<7> dyn/cm<2> or more at 100 deg.C, 1×10<6> dyn/cm<2> or more at 130 deg.C, 4×10<5> -6×10<6> dyn/cm<6> at 140 deg.C, and tan δ (loss modulus/storage elastic molulus)=0.05 or more at 50 deg.C, 100 deg.C, 130 deg.C and 140 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crosslinked foamed polypropylene resin sheet suitable as a skin material (cushion material) for an automobile interior material obtained by a skin molding method or the like, and a foamed particle molded article obtained by laminating the foamed sheet. And a method for producing the same.

[0002]

2. Description of the Related Art Crosslinked polypropylene resin foam sheets are excellent in heat resistance, rigidity, moldability, chemical resistance, etc., and have been developed for use in various fields such as automotive interior materials, household goods, and building materials. It is a growing material. For example, in the stamping molding method, composite molding is performed under severe conditions in which a molten resin is laminated on a crosslinked foamed polypropylene resin sheet and pressed under high pressure conditions. However, in recent years, a stamping molded product of a crosslinked foamed polypropylene resin sheet is desired to have a more complicated shape than a relatively simple shape such as an automobile ceiling material. Deep drawing formability is required. Further, as an application other than the foam sheet in the stamping molding method, the so-called skin molding method in which the two are compositely integrated by filling the foam particles in a mold equipped with a resin sheet and heating with a heating medium is used. There is a need for a crosslinked polypropylene resin foam sheet having excellent adhesiveness, moldability, heat resistance, and cushioning properties that can be used as a resin sheet.

[0003]

DISCLOSURE OF THE INVENTION The present invention is intended to maintain a sufficient cushioning property without crushing or tearing of a foam even under severe molding processing, and to provide an adhesive workability with other composite materials. It is an object of the present invention to provide a cross-linked foamed polypropylene resin sheet having a good thermal conductivity. Another object of the present invention is to provide a method for producing a laminated foamed particle molded article by a skin molding method using the foamed sheet.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, a foamed sheet using a polypropylene-based resin as a base resin has a storage elastic modulus of 3 × 10 ⁷ at 50 ° C. in a tensile measurement.
~ 3 × 10 ⁸ dynes / cm ² , 1 × 10 ⁷ dy at 100 ° C.
n / cm ² or more, 1 × 10 ⁶ dyn / cm ² or more at 130 ° C., 4 × 10 ^{5 to} 6 × 10 ⁶ dyn / cm ² at 140 ° C., and 50 ° C., 100 ° C., 130 ° C., 140 ° C. Tan δ (loss modulus / storage modulus) of 0.05 or more is provided. Further, according to the present invention, after mounting the polypropylene-based resin crosslinked foamed sheet in a mold, filling the mold with foamed polypropylene-based resin particles,
There is provided a method for producing a foamed sheet-laminated foamed particle molded article, characterized in that the foamed particles are fused together by heating with steam, and the foamed particles and the foamed sheet are fused and integrated.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The crosslinked foamed polypropylene resin sheet of the present invention has a storage elastic modulus of 3 × 10 ⁷ at 50 ° C.
３3 × 10 ⁸ dyn / cm ² , preferably 5 × 10 ⁷ to 2
× 10 ⁸ dyn / cm ² , 1 × 10 ⁷ dyn /
cm ² or more, preferably 2 × 10 ^{7 to} 6 × 10 ⁸ dyn /
cm ^2, 130 ° C. at 1 × 10 ⁶ dyn / cm ² or more, preferably ^{3 × 10 6 ~2 × 10 7} dyn / cm 2, 140 ℃
4 × 10 ^{5 to} 6 × 10 ⁶ dyn / cm ² , preferably 6
× 10 ^{5 to} 5 × 10 ⁶ dyn / cm ² , and 50
The value of tan δ (loss modulus / storage modulus) at ° C, 100 ° C, 130 ° C, and 140 ° C is 0.05 or more, preferably 0.06 or more. In this specification, the storage elastic modulus (dy) of the foamed sheet is used.
n / cm ² ) and tan δ (loss modulus / storage modulus)
The values were determined as follows. First, the surface layer is sliced from the foam sheet surface to prepare a test piece having a width of 5.0 mm and a thickness of 1.3 mm. The width of the foam sheet was divided into five, the width direction of the test piece was matched with the width direction of the foam sheet from both sides of the foam sheet in each divided area, and the slice was performed. Get. Next, as a measuring device, a viscoelasticity measuring device SOLIDS ANAL manufactured by Rheometric Scientific Inc. was used.
Using YZER RSAII and a film tension fixture as its accessories, adjusting the initial gap between the chucks to 22.6 mm ± 0.5 mm using a spacer, attaching the test piece, and adjusting the initial load to 10 g. Then, close the oven and heat at a heating rate of 3 ° C / min.
Hz (6.28 rad / sec), set distortion 0.
The storage elastic modulus (dyn / cm ² ) and tan δ value of the test piece at 50 ° C., 100 ° C., 130 ° C., and 140 ° C. are determined by using the auto tension function at 1%. And
They storage modulus at each temperature (dyn / cm ²⁾ and tan [delta value arithmetic mean with a storage elastic modulus of the foam sheet (dyn / cm ²⁾ and the value of tan [delta.

In the present invention, the storage modulus (dyn / c)
The values of m ² ) and tan δ are specified for the following reasons. Generally, in the case of a crosslinked foam of a polypropylene resin, the gel fraction is used as an index of the moldability and heat resistance of the foam. However, it is not possible to accurately detect the crosslinked state by itself. It is not possible to accurately correlate the laminating adhesiveness with the like. For example, even when the gel fraction is the same, the behavior of the foam at the time of heating greatly changes due to a difference in the type and amount of the crosslinking aid and a difference in crosslinking conditions. Therefore, in order to grasp the behavior of the foam during heating, the storage elastic modulus (dyn / cm ² ) and ta
It is necessary to use the value of nδ as an index.

The storage elasticity index of the foamed sheet specified in the present invention will be described in detail. In the foamed sheet, the storage elasticity below the heat distortion temperature well reflects the compression recovery property and the compressive strength of the foamed sheet during normal use. On the other hand, it can be said that the storage elastic modulus not lower than the heat distortion temperature and not higher than the crystal melting end temperature well reflects the maintenance and destruction of bubbles during the heating and softening of the foamed sheet and the melting characteristics of the base resin. Specifically, when the storage elastic modulus at 140 ° C. is more than 6 × 10 ⁶ dyn / cm ² ,
At the time of skin molding, etc., the adhesion to other polypropylene resin and the anchor effect are low, and the adhesiveness is reduced. Further, in the heating vacuum forming, the elongation at the time of heating is poor and is not suitable for deep drawing. On the other hand, the storage elastic modulus at 140 ° C. and 130 ° C. is less than 4 × 10 ⁵ dyn / cm ² , respectively, and 1 × 10 ⁶
If it is less than dyn / cm ^2, the bubbles on the surface of the foamed sheet are apt to be broken by heating vacuum molding or the like, and the heating molding time adjustment range is narrow, resulting in poor productivity. In addition, there is a pressure of 1 to 5 kg / cm ^{2 on the} sheet, such as skin mold molding or bonding other propylene-based resin sheets to the foam sheet, and the sheet is crushed without withstanding the pressure, and the thickness of the foam sheet is reduced. Is significantly reduced, and the resulting molded article does not have sufficient cushioning properties. Particularly, the storage elastic modulus at 140 ° C. is preferably from 6 × 10 ^{5 to} 5 × 10 ⁶ dyn / c.
m ² , more preferably 1 × 10 ^{6 to} 5 × 10 ⁶ dy
n / cm ² . Further, the storage elastic modulus at 130 ° C. is preferably 3 × 10 ⁶ to 2 × 10 ⁷ dyn / cm ² . The storage elastic modulus at 50 ° C. is 3 × 10 ⁸ dyn /
If it exceeds cm ² , sufficient cushioning properties as a foam cannot be obtained. Further, when used in stamping molding, uniform elongation cannot be obtained, and uneven thickness and partial destruction are likely to occur. Storage elastic modulus at 50 ° C. and 100 ° C. is less than 3 × 10 ⁷ dyn / cm ² and 1 × 10 ⁷ d, respectively.
In the case of less than yn / cm ² , deformation is large even with a small load, and it is easy to be crushed. However, depending on the application, the thickness is limited, so that the required thickness may not be selected, and as a result, a sufficient cushioning property cannot be obtained.

[0008] Next, ta of the foam sheet specified in the present invention.
When the index of nδ is described in detail, the tan δ value is a ratio of the loss elastic modulus and the storage elastic modulus, so that if the tan δ value is small, the property of trying to return to the mechanical deformation of the foamed sheet is strong, and the tan δ value is A larger size means that the foamed sheet is more likely to remain deformed with respect to mechanical deformation. Therefore, if the tan δ value is small, the force of returning to the original state in the molding of the foamed sheet is concentrated on the surface of the foamed sheet, a thin portion, and the like, and the foamed sheet is torn,
Deformation will occur. Therefore, in the present invention, the value of tan δ (loss modulus / storage modulus) at each of 50 ° C., 100 ° C., 130 ° C., and 140 ° C. is 0.05.
If it is less than 3, the shape is difficult to maintain even after molding, the dimensional stability is deteriorated, and the foamed sheet may be broken.

The polypropylene resin as the base resin of the crosslinked foamed polypropylene resin sheet of the present invention includes polypropylene, a mixture of 50% by weight or more of polypropylene and another thermoplastic resin such as polyethylene, and the like.
Examples of the polypropylene include propylene homopolymer, propylene / ethylene copolymer and propylene / α-
Olefin copolymers can be mentioned. Where α
-Olefins such as butene-1, pentene-1, hexene-1, and 4-methylpentene having 4 to 10 carbon atoms;
Olefins are included. Examples of the propylene / ethylene copolymer and propylene / α-olefin copolymer include ethylene / propylene random copolymer, same block copolymer, butene / propylene random copolymer, same block copolymer, and ethylene / propylene / Butene random copolymers and the same block copolymers. Among them, ethylene / propylene random copolymers and block copolymers are preferred, and ethylene / propylene random copolymers are more preferred. The content of ethylene or α-olefin in the propylene / ethylene copolymer or propylene / α-olefin copolymer is 1 to 30% by weight,
Preferably it is 1 to 8% by weight. Examples of the other thermoplastic resin include polyethylene, polystyrene, polyvinyl chloride, acrylic resin, and ethylene / vinyl acetate copolymer. Particularly, polyethylene includes low-density polyethylene, high-density polyethylene, linear High-density polyethylene, linear ultra-low-density polyethylene, and the like. Further, in the present invention, a rubber component such as ethylene / propylene rubber may be blended for the purpose of improving flexibility and imparting other properties to the base resin. The amount of the rubber component added is less than 30% by weight, usually 2 to 2%.
Preferably it is in the range of 5% by weight.

The production of the crosslinked foamed polypropylene resin sheet is carried out as follows. The extruder is supplied with the base resin and the thermal decomposition type foaming agent, and a crosslinking accelerator such as divinylbenzene as necessary, and kneaded at a temperature lower than the decomposition start temperature of the thermal decomposition type foaming agent to obtain a foamable molten gel. The foamable molten gel is extruded from a T-die attached to the tip of the extruder without foaming, and is immediately applied to a calender roll to obtain a foamable polypropylene resin sheet. Subsequently, after performing a cross-linking treatment on the expandable polypropylene-based resin sheet, the sheet is introduced into a heating furnace to decompose the foaming agent, whereby a cross-linked foamed polypropylene-based resin sheet can be obtained.

Examples of the thermal decomposition type blowing agent include azodicarbonamide, azobisformamide, N, N-dinitrosopentamethylenetetramine, diazoaminobenzene, benzenesulfonylhydrazide, P, P-oxybisbenzenesulfonylhydrazide, N, N And dinitrosoterephthalamide. Among them, azodicarbonamide is most preferred in view of thermal stability and high decomposition initiation temperature. These foaming agents may be used alone or in combination of two or more. The amount of the pyrolytic foaming agent used in the present invention is 0.2 to 30 parts by weight, preferably 1 to 100 parts by weight of the base resin.
-20 parts by weight.

As the method of crosslinking the foamed sheet in the present invention, a method such as ionizing radiation crosslinking, so-called chemical crosslinking using a chemical crosslinking agent, or so-called silane crosslinking in which a silyl group is introduced into a resin to perform crosslinking is employed. be able to. In particular, the silane cross-linking method is preferable because a uniform cross-linking structure is obtained from the sheet surface to the inside by introducing a cross-linking structure into the base resin constituting the foamed sheet, and the obtained foamed sheet has uniform physical properties. Becomes Furthermore,
Although the reason is not clear, the smoothness of the foam sheet surface is also significantly improved.

In general, in a crosslinked polypropylene resin foam, the gel fraction is used as an index of the crosslinked state related to the heat moldability, in addition to the density of the foam. Adhesiveness with other resins cannot be related. For example, even when the gel fraction is the same, the behavior of the foam at the time of heating greatly changes due to a difference in the type and amount of the crosslinking aid and a difference in crosslinking conditions. Therefore, in order to grasp the behavior of the foam during heating, it is preferable to adjust the degree of swelling in addition to the gel fraction. Therefore, the crosslinked polypropylene resin foam sheet of the present invention can be obtained by adjusting the gel fraction and the degree of swelling. However, the adjustment range of the gel fraction and the degree of swelling of the foamed sheet targeted for obtaining the foamed sheet of the present invention is different depending on the crosslinking method as described above, so that the silane crosslinked foamed sheet, the chemically crosslinked foamed sheet, the radiation crosslinked It should be noted that there are differences between foam sheets. This is considered to be due to the uniformity of the crosslinked structure and the difference in the crosslinked structure of the crosslinked foamed sheet. When the degree of swelling is too large or the gel fraction is too small, the storage modulus of the foamed sheet at 130 ° C. and 140 ° C. is less than 1 × 10 ⁶ dyn / cm ² and 4 × 10 ⁵ dyn, respectively. / Cm ² . on the other hand,
When the degree of swelling is too small or the gel fraction is too large, the storage elastic modulus of the foamed sheet is 6 × 10 ⁶ dyn at 140 ° C.
/ Cm ² .

In the present invention, the polypropylene resin crosslinked foamed sheet having the viscoelastic properties is obtained by using the base resin as described above to obtain a foamed sheet. Is 0.03 to 0.2 g / cm ³ , preferably 0.03 to 0.2 g / cm ³ .
The type and amount of the foaming agent are adjusted so as to obtain a foamed sheet of 36 to 0.100 g / cm ³ , and the amount of the silane-grafted propylene-based resin is adjusted to 20 to 90% by weight, preferably 3 to 30% by weight.
0 to 70% by weight, the raw materials are blended so that the gel fraction is 25 to 70%, preferably 30 to 60%, and the degree of swelling is 1000 to 9000%, preferably 2000 to 8000%.
The crosslinked foamable sheet is obtained by selecting the production conditions and the like, and the crosslinked foamable sheet is obtained by adjusting the heating and foaming conditions.

In the present specification, the gel fraction is defined as
It shows the cross-linking ratio of the cross-linked foamed polypropylene resin sheet. The value is measured by cutting out a sample of about 1 g from the foamed sheet, weighing the sample, placing the sample in 200 ml of xylene, and heating for 24 hours. After reflux, JIS
74 μm specified in Z8801 (1966)
The insolubles were quickly filtered through a wire mesh, and the insolubles were dried under reduced pressure for 24 hours. The same operation (from reflux to drying under reduced pressure) was repeated once again using the insolubles as a sample, and finally the remaining insolubles were removed. The weight (g) is measured and calculated by the following equation. Gel fraction (%) = (weight of insoluble matter / weight of sample used for measurement) × 100 The degree of swelling is the same as in the measurement of the gel fraction. The residue from which xylene eluted was removed was immediately placed in a sealed container, and the weight of the residue upon swelling of xylene was measured.Then, the residue was dried under reduced pressure for 24 hours to measure the dry residue weight.
It is calculated by the following equation. Degree of swelling (%) = (weight of residue upon swelling xylene / weight of dry residue) × 100

The crosslinked foamed polypropylene resin sheet of the present invention obtained as described above has a density of 0.03.
-0.2 g / cm ³ , preferably 0.036-0.1 g
/ Cm ³ is more preferred. The thickness is 1 to 20
mm is preferable, and 2-5 mm is more preferable.

Next, a method of producing a foamed sheet-laminated foamed particle molded article by the so-called skin mold molding method of the present invention using the polypropylene resin crosslinked foamed sheet will be described. The polypropylene resin used for the expanded polypropylene resin particles used in the present invention,
(1) a propylene homopolymer, and (2) a propylene-based copolymer having a propylene content of 70% by weight or more, such as a propylene-ethylene block copolymer, a propylene-ethylene random copolymer, a propylene-butene random copolymer, and a propylene-ethylene-butene random copolymer. The main component is 1 or 2 or more selected from the group of (herein, it means 70% by weight or more). Such a main component polypropylene-based resin has a melting point of 13 in order to impart heat resistance and rigidity to an in-mold molded article of foamed particles, and further to a foamed molded article with a skin material.
It is desired to use those having a temperature of 0 ° C or higher, preferably 135 ° C or higher. However, it is desirable to set the upper limit of the melting point to 166 ° C., because the equipment cost can be reduced. Further, the auxiliary component polymer may be blended with the main component polypropylene resin according to various purposes. Such sub-components include polyethylene resins such as linear ultra low density polyethylene, branched low density polyethylene resin, linear low density polyethylene resin, medium density polyethylene resin, and high density polyethylene resin; ethylene-propylene rubber; Examples thereof include polyolefin-based elastomers such as ethylene-butene rubber, ethylene-octene rubber, and propylene-butene rubber; and one or more polyolefin-based (co) polymers selected from polybutene resins.

As a method for producing the polypropylene resin foam particles, for example, an inorganic gas foaming agent and / or a volatile organic foaming agent are mixed in a sealed pressure vessel while stirring the polypropylene resin particles in water. Conventionally known methods such as impregnation, heating to a predetermined foaming temperature under pressure, and then discharging to a low pressure region may be mentioned, but the present invention is not limited by such a method. The bulk expansion ratio of the expanded polypropylene resin particles is preferably 3 to 60 times. More preferably, it is 3 to 20 times. Further, among the polypropylene-based trees constituting the foamed particles, Japanese Patent Application Laid-Open No.
It is desirable that a secondary crystal as described in Japanese Patent No. 738 is present.

The foamed sheet laminated foamed particle molded article is manufactured by integrally molding a crosslinked foamed sheet (skin material) disposed in a mold at the same time as molding the foamed particles in the mold. The method will be described with reference to the drawings. FIG. 1 is a schematic view of an example of a mold for integral molding, whereby a crosslinked foamed sheet laminated foamed particle molded article is manufactured. First, the cross-linked foamed polypropylene resin sheet 1 is placed on the mold A (2a) side, suctioned from the vacuum suction pipe 3a, and attached to the mold A. At this time, it is also possible to use, as the foamed sheet 1, one that has been thermoformed in advance into a shape that can conform to the inner surface shape of the mold A. Use by fixing and suction-adhering to the inner surface of the mold A without heating, or by heating and softening as necessary, and then vacuum forming or compressing the inner surface of the mold A. Is also possible. Then, mold A and mold B
After filling the polypropylene resin expanded particles P into the cavity 4 formed between the expanded sheet 1 and the mold B when the (2b) is matched with the mold through the feeder 11, it is necessary for in-mold molding of the expanded particles. Pressurized steam is supplied between the foamed particles through the chamber 7b from the steam introduction pipe 8b and heated to perform in-mold molding to obtain a foamed sheet laminated foamed body. The pressurized steam is also supplied to the chamber 7a from the steam introduction pipe 8a, but is not supplied to the cavity 4, but only heats the surface of the mold A (2a). The mold A is provided with a plurality of vacuum suction holes 5 having a diameter of 0.2 to 1.0 mm in order to form or adhere the foam sheet 1 toward the mold A (2a). The mold B is provided with slit holes 6 and the like for supplying pressurized steam toward the foamed particles in the cavity 4. Further, cooling water introduction pipes 9a and 9b are provided for cooling, and drain discharge pipes 10a and 10b are provided for draining the cooling water.

When the foamed sheet laminated foamed particle molded article is used as a cushion material, it is preferable that the surface of the crosslinked polypropylene resin foamed sheet is laminated with a surface material. Lamination is usually performed after the production of the foamed sheet. As the surface material, in addition to sheets made of polyvinyl chloride or polyolefin elastomer, highly decorative materials used for interior surface materials of vehicles and the like, such as polyester woven fabric / nonwoven fabric and polypropylene woven fabric / nonwoven fabric. The material is exemplified. Therefore, when the material is a sheet made of polyvinyl chloride, polyolefin elastomer, or the like, it is desirable in appearance that a grain pattern or the like is transferred. When these surface materials have thermal adhesiveness to the crosslinked foamed sheet, it is desirable that they are thermally bonded without using an adhesive. When the surface material does not have thermal adhesiveness to the crosslinked foam sheet, it is necessary to use an adhesive.

When a foamed sheet laminated foamed particle molded article (foamed particle molded article with a skin material) is used for a vehicle interior material, the polypropylene resin crosslinked foamed sheet has a soft feeling, and the polypropylene resin foam It is desired that the in-mold molded product of the particles be lightweight and have rigidity (shape retention), and for that purpose, the apparent density of the crosslinked foamed sheet is set to 0.02 to 0.02.
0.09 g / cm ³ , more preferably 0.03 to 0.0
6 g / cm ³ , thickness 1-10 mm, more preferably 2
To 5 mm, and the apparent density of the in-mold foamed particle molded product is 0.036 to 0.3 g / cm ³ , more preferably 0.03 to 0.3 g / cm ³ .
It is good to be 45-0.18 g / cm ³ .

[0022]

Next, the present invention will be described in more detail by way of examples. Examples 1 to 4 and Comparative Examples 1 and 2 The amounts of the silanol condensation catalyst, azodicarbonamide (pyrolytic foaming agent) shown in Table 1 and the base resin shown in Table 1 were supplied to a twin-screw extruder and foamed. The mixture was melt-kneaded under a temperature condition lower than the decomposition temperature of the agent, extruded from a 410 mm wide coat hanger type T die attached to the tip of the extruder, and immediately applied to a calender roll to obtain a sheet-like molded product. The obtained molded article was crosslinked in the presence of moisture to obtain a crosslinked foamable sheet. The swelling degree of the obtained crosslinked foamable sheet is also shown in Table 1. Next, the cross-linked foamable sheet was obtained by heating the cross-linked foamable sheet in a heating furnace under a heating condition of an ambient temperature of 220 to 240 ° C. Table 2 shows the apparent density, storage modulus and tan δ value of the obtained crosslinked foamed sheet. Next, the crosslinked foamed sheet was cut into a 200 mm square, and this was cut into a molding machine having a cavity space of 200 mm (length) × 500 mm (width) × 20 mm (thickness) so that the crosslinked foamed sheet adhered to the inner surface of the mold A shown in FIG. Using a vacuum pump to suction-fix through the suction holes formed in the mold A, then mold A
And the mold B, and the cavity 4 is filled in the cavity 4 with a propylene-ethylene random copolymer (ethylene component 2.) which has been adjusted in advance so that the air pressure in the foamed particles becomes 2.5 atm.
Foamed particles (4% by weight, melting point: 146.0 ° C.) (bulk expansion ratio: 15 times) were filled from the mold B side. Further, steam was introduced into the chamber on the mold B side for 5 seconds while the drain valve was opened to exhaust air existing between the foamed particles, and then the drain valve was closed. 3.8 kg
/ Cm ² G steam and 2 kg / cm ² G steam were introduced into the mold A steam chamber, followed by molding, followed by water cooling, and a cross-linked foam sheet (skin material) integrated on one side. Was obtained.

With respect to the obtained crosslinked foamed sheet laminated foamed particle molded article, the adhesiveness of the crosslinked foamed sheet, the thickness of the crosslinked foamed sheet, and the moldability of the crosslinked foamed sheet were evaluated based on the following evaluation criteria. 2 is shown. (Adhesiveness of crosslinked foamed sheet) ：: Material destruction is observed on the entire surface of the foamed sheet on the peeled surface of the foamed sheet. Δ: Material destruction is partially observed in the foam sheet on the foam sheet release surface. X: No material destruction is observed in the foamed sheet on the foamed sheet peeling surface. (Thickness maintenance of crosslinked foamed sheet) ○: The thickness of the foamed sheet before molding is almost maintained. Δ: The thickness of the foam sheet before molding was crushed by half or less, but the cushioning property of the foam sheet was left. X: The thickness of the foam sheet before molding hardly remains, and the cushioning property of the foam sheet cannot be confirmed by touch. (Formability of crosslinked foamed sheet) ：: The foamed sheet in the molded article has a uniform thickness as a whole, and a sharp molded article according to the mold can be obtained. Δ: The foamed sheet is partially thin, such as at the corner of the molded body, but a sharp molded body according to the mold is obtained. ×: There are problems such as drawdown during heating and cutting of the foam sheet, and a good molded body cannot be obtained.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

The cross-linked foamed polypropylene resin sheet of the present invention has excellent heat resistance in mold molding by vacuum, air pressure, etc., so that bubbles on the sheet surface may be broken by heat when the sheet is heated. And has excellent deep drawability and a wide temperature range in which heat molding is possible. And
It is also excellent in flexibility and cushioning. In particular, using the foamed sheet of the present invention, a foamed sheet laminated foamed particle molded article can be suitably produced by a so-called skin mold molding method. According to this manufacturing method, the adhesion between the foam sheet, the foam sheet, and the foamed particle molded body is good,
A foamed sheet-laminated foamed particle molded article having no breakage during molding or shrinkage of the molded article, excellent heat resistance, and excellent cushioning properties in the surface layer can be obtained. Further, the foamed sheet of the present invention can be applied to a sheet having a complicated shape in a stamping molding method.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a method for producing a foamed sheet laminated foamed particle molded article (foam molded article with a skin material) of the present invention using a mold for integral molding.

[Explanation of symbols]

 1 Crosslinked foamed sheet of polypropylene resin (skin material) 2a Mold A 2b Mold B 3a, 3b Vacuum suction tube 4 Cavity 5 Vacuum suction hole 6 Slit hole 7a, 7b Chamber 8a, 8b Steam introduction tube 9a, 9b Cooling water introduction Pipe 10a, 10b Drain discharge pipe 11 Feeder P Polypropylene resin foam particles

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 9:00

Claims (2)

[Claims] 1. A foamed sheet comprising a polypropylene-based resin as a base resin, wherein the foamed sheet has a storage elastic modulus in a tensile measurement of 3 × 10 ^{7 to} 3 × 10 ⁸ dyn / 50 ° C.
cm ² , 1 × 10 ⁷ dyn / cm ² or more at 100 ° C., 13
1 × 10 ⁶ dyn / cm ² or more at 0 ° C., 4 × 1 at 140 ° C.
0 ^{5 to} 6 × 10 ⁶ dyn / cm ² and at 50 ° C., 1
A crosslinked polypropylene-based resin foam sheet having a tan δ (loss modulus / storage modulus) at 00 ° C, 130 ° C, and 140 ° C of 0.05 or more. 2. After mounting the crosslinked foamed polypropylene resin sheet according to claim 1 in a mold, the foamed polypropylene resin particles are filled in the mold and heated with steam to fuse the foamed particles to each other. And a method for producing a foamed sheet-laminated foamed particle molded article, wherein the foamed particle and the foamed sheet are fused and integrated.