JP4190314B2 - Molding - Google Patents

Description

【００９１】
以上述べたように、本発明の成形品におけるポリオレフィン系樹脂架橋発泡シートは、示差走査熱量分析による融解吸熱ピーク温度の内の少なくとも一つが１４０℃以上であるポリオレフィン系樹脂からなり、見掛け密度が０．０４０〜０．２００ｇ／ｃｍ³ であり且つ常温における２５％圧縮強度が０．９８〜９．８０Ｎ／ｃｍ² であると共に、１６０℃での１００％モジュラスの最大値と、この１００％モジュラスの最大値をとる方向に直交する方向における１６０℃での１００％モジュラスとの平均値が９．８〜１９．６Ｎ／ｃｍ² であるので、機械的強度、耐熱性、柔軟性及び伸び等の物性バランスに優れていると共に成形性にも優れており、このポリオレフィン系樹脂架橋発泡シートを用いた成形品は、ポリオレフィン系樹脂架橋発泡シートに破れ等がない優れた外観性を有していると共に柔軟性及び触感に優れ略正確な寸法を有しており、例えば、車両内装材のような複雑な形状を有する成形品として好適に用いることができる。
【００９２】
そして、上記本発明の成形品におけるポリオレフィン系樹脂架橋発泡シートにおいて、常温での引張強度の最大値と、この引張強度の最大値をとる方向に直交する方向における常温での引張強度との平均値が１１７．６〜２４５．０Ｎ／ｃｍ² である場合には、機械的強度、耐熱性、柔軟性及び伸び等の物性バランス並びに成形性に更に優れており、このポリオレフィン系樹脂架橋発泡シートを用いた成形品は、表皮材に皺や凹凸が殆どない優れた外観性を有していると共に優れた柔軟性を有しており、高度な外観性及び触感が要求される用途にも好適に用いることができる。
【図面の簡単な説明】
【図１】図１は、ポリオレフィン系樹脂架橋発泡シートにおける１６０℃での１００％モジュラスの最大値と、この１００％モジュラスの最大値をとる方向に直交する方向における１６０℃での１００％モジュラスとの平均値、及び、常温での引張強度の最大値と、この引張強度の最大値をとる方向に直交する方向における常温での引張強度との平均値を測定する際に用いられる試験片の作製要領を示した平面図である。
【図２】図２は、上記試験片を示した平面図である。
【符号の説明】
Ａ₁ 〜Ａ₁₈ ポリオレフィン系樹脂架橋発泡シート
Ｄ 試験片[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molded article using a polyolefin-based resin crosslinked foamed sheet that is excellent in a balance of physical properties such as mechanical strength, heat resistance, flexibility and elongation, and can be molded into a complicated shape.
[0002]
[Prior art]
Conventionally, a crosslinked foamed sheet made of a polyolefin-based resin is widely used as a vehicle interior material such as a ceiling, a door, and an instrument panel because it is excellent in flexibility, heat resistance, mechanical strength, and the like.
[0003]
As such a polyolefin resin crosslinked foamed sheet, for example, Patent Document 1 discloses polyethylene and / or ethylene copolymer, ethylene-butene-propylene copolymer A having a melting point of 130 to 160 ° C., A foaming agent and a crosslinking agent and / or a crosslinking accelerator are added to and mixed with a mixture of a polypropylene and / or a propylene copolymer having a melting point higher by 10 ° C. than the melting point of the coalescence A, and are crosslinked and foamed. A method for producing a polyolefin resin cross-linked foam sheet is disclosed.
[0004]
However, the polyolefin resin crosslinked foamed sheet obtained by the production method disclosed in the above publication has a problem that the flexibility is insufficient, and it is broken when the polyolefin resin crosslinked foamed sheet is molded into a complicated shape. There was a problem that occurred.
[0005]
Furthermore, Patent Document 2 discloses that 25% compressive strength at normal temperature is 4.9 to 11.8 N / cm. ² 100% modulus at 120 ° C. of 15.7 to 29.4 N / cm ² 100% modulus at 160 ° C. of 3.9 to 9.8 N / cm ² And a polyolefin resin cross-linked foam sheet characterized by a specific gravity of 0.04 to 0.20.
[0006]
However, the polyolefin-based resin crosslinked foamed sheet disclosed in the above publication has a problem that heat resistance is insufficient in molding into a molded product having a complicated shape which has been increasing in recent years, and, for example, stamping There was a problem that the mechanical strength at room temperature required for molding was insufficient.
[0007]
[Patent Document 1]
Japanese Patent Publication No. 2-38100
[Patent Document 2]
JP 2000-355085 A
[0008]
[Problems to be solved by the invention]
An object of the present invention is a polyolefin-based resin-crosslinked foamed sheet that has an excellent balance of physical properties such as mechanical strength, heat resistance, flexibility, and elongation, and can obtain a molded product having a complicated shape using a molding method such as stamping molding. The object is to provide a molded article using
[0009]
[Means for Solving the Problems]
The molded article of the present invention is It consists of 10-50% by weight of polyethylene resin, 10-40% by weight of polypropylene homopolymer and 20-50% by weight of thermoplastic olefin elastomer. , At least one of the melting endothermic peak temperatures determined by differential scanning calorimetry is a polyolefin resin having a temperature of 140 ° C. or higher, and an apparent density of 0.040 to 0.200 g / cm ^Three And 25% compressive strength at room temperature is 0.98 to 9.80 N / cm ² The average value of the maximum value of 100% modulus at 160 ° C. and the 100% modulus at 160 ° C. in the direction orthogonal to the direction taking the maximum value of 100% modulus is 9.8 to 19.6 N / Cm ² A thermoplastic resin is laminated and integrated on one surface of the polyolefin resin crosslinked foamed sheet, and is molded into a desired shape.
[0010]
In the polyolefin resin used in the present invention, it is necessary that at least one of melting endothermic peak temperatures by differential scanning calorimetry is 140 ° C. or higher. That is, when there are a plurality of melting endothermic peak temperatures by differential scanning calorimetry in a polyolefin resin, at least one of them must be 140 ° C. or higher.
[0011]
This is because when the melting endothermic peak temperature of the polyolefin resin is less than 140 ° C., the mechanical strength and heat resistance of the resulting polyolefin resin crosslinked foamed sheet are insufficient.
[0012]
Examples of such a polyolefin resin include a polyethylene resin, a polypropylene resin, and a thermoplastic polyolefin elastomer. Polyolefin resins may be used alone or in combination of two or more. When two or more types of polyolefin resins are used in combination, at least one type of polyolefin resin having at least one melting endothermic peak temperature of 140 ° C. or higher by differential scanning calorimetry is included. Good.
[0013]
Examples of the polyethylene-based resin include, for example, ultra-low density polyethylene, low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, and the like, ethylene containing 50% by weight or more of ethylene and a polymerizable monomer And a copolymer thereof. Polyethylene resins may be used alone or in combination of two or more.
[0014]
Examples of the polymerizable monomer copolymerizable with ethylene include α-olefins such as propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene and 1-octene. Vinyl acetate, acrylic acid, methacrylic acid, acrylic ester, methacrylic ester and the like. A polymerizable monomer may be used independently or 2 or more types may be used together.
[0015]
Furthermore, examples of the polypropylene resin include a propylene homopolymer, a copolymer of propylene and a polymerizable monomer containing 50% by weight or more of propylene, and the like. Polypropylene resins may be used alone or in combination of two or more.
[0016]
Examples of the polymerizable monomer copolymerizable with propylene include α-, such as ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, and 1-octene. Examples include olefins. The polymerizable monomer copolymerizable with propylene may be used alone or in combination of two or more.
[0017]
The content of α-olefin in the propylene-α-olefin copolymer is preferably 1 to 8% by weight, and more preferably 2 to 5% by weight. If the content of α-olefin in the propylene-α-olefin copolymer is less than 1% by weight, the flexibility and elongation of the resulting polyolefin-based resin crosslinked foamed sheet may be insufficient, Moreover, when it exceeds 8 weight%, it is because the surface property (appearance) of the polyolefin resin crosslinked foamed sheet obtained may be impaired.
[0018]
The thermoplastic polyolefin-based elastomer exhibits rubber elasticity at room temperature, and is plasticized at high temperature to enable various molding processes. Generally, a soft segment (rubber component) having entropy elasticity in a molecule and In many cases, it shares a hard segment (molecularly constrained component) to prevent plastic deformation and may have a partially crosslinked structure within the moldable range, but it has a wide range of three-dimensional crosslinked structures (network structure) ) Does not have.
[0019]
As such a thermoplastic polyolefin elastomer, for example, a block copolymer having polyethylene as a soft segment, a copolymer of ethylene and a small amount of a diene or a partially cross-linked product thereof, and polypropylene as a hard segment. And polyolefin elastomers. The thermoplastic polyolefin elastomer may be used alone or in combination of two or more.
[0020]
As the polyolefin-based resin, a balance of physical properties such as mechanical strength, heat resistance, flexibility, and elongation is further improved. Therefore, the polyolefin-based resin is a mixture of a polypropylene-based resin and a polyethylene-based resin. A mixture comprising at least% by weight, a polyethylene resin, a propylene homopolymer and a thermoplastic polyolefin elastomer is preferred, and a mixture comprising a polyethylene resin, a propylene homopolymer and a thermoplastic polyolefin elastomer is more preferred.
[0021]
And, as a polyolefin resin, in the case of using a mixture of a polypropylene resin and a polyethylene resin and containing 50% by weight or more of a polypropylene resin, the content of the polypropylene resin in the polyolefin resin is If the amount is small, the heat resistance of the resulting polyolefin-based resin crosslinked foamed sheet may be insufficient, and if it is large, the flexibility and elongation of the resulting polyolefin-based resin crosslinked foamed sheet may be insufficient. 55 to 90% by weight is preferred.
[0022]
Further, when a mixture comprising a polyethylene resin, a propylene homopolymer and a thermoplastic polyolefin elastomer is used as the polyolefin resin, the polyethylene resin is 10 to 50% by weight, the propylene homopolymer is 10 to 40% by weight and the heat A polyolefin resin comprising 20 to 50% by weight of a plastic polyolefin elastomer is preferred. In addition, it is necessary to adjust so that the sum total of a polyethylene-type resin, a propylene homopolymer, and a thermoplastic polyolefin-type elastomer may be 100 weight%.
[0023]
If the content of the polyethylene resin in the polyolefin resin is less than 10% by weight, the flexibility and mechanical strength at room temperature of the resulting polyolefin resin crosslinked foamed sheet may be insufficient. Moreover, when it exceeds 50 weight%, it is because the heat resistance of the polyolefin resin crosslinked foamed sheet obtained may become inadequate.
[0024]
And if the content of the propylene homopolymer in the polyolefin resin mixture is less than 10% by weight, the mechanical strength and heat resistance of the resulting polyolefin resin crosslinked foamed sheet may be insufficient, This is because if it exceeds 40% by weight, flexibility and elongation of the resulting polyolefin resin-crosslinked foamed sheet may be insufficient.
[0025]
Furthermore, if the content of the thermoplastic polyolefin elastomer in the polyolefin resin is less than 20% by weight, the flexibility and elongation of the resulting polyolefin resin crosslinked foamed sheet may be insufficient, and 50 wt. It is because the heat resistance of the polyolefin-type resin crosslinked foamed sheet obtained may become inadequate when it exceeds%.
[0026]
If the apparent density of the polyolefin resin crosslinked foamed sheet is small, the heat resistance of the polyolefin resin crosslinked foamed sheet is insufficient, and bubbles (cells) are destroyed during heat molding. Since the flexibility and elongation of the crosslinked foamed sheet are insufficient, 0.040 to 0.200 g / cm. ^Three It is limited to. In addition, the apparent density of the polyolefin-based resin crosslinked foamed sheet refers to a value measured according to JIS K6767 “Foamed Plastics—Polyethylene Test Method”.
[0027]
In addition, when the 25% compressive strength at room temperature in the polyolefin resin crosslinked foamed sheet is small, the apparent density and crystal content of the polyolefin resin crosslinked foamed sheet are lowered, resulting in insufficient mechanical strength and heat resistance. If it is large, the flexibility and elongation of the polyolefin-based resin crosslinked foamed sheet will be insufficient, so 0.98 to 9.80 N / cm. ² It is limited to. In addition, 25% compressive strength at normal temperature in a polyolefin-type resin crosslinked foamed sheet means 25% compressive strength measured based on JISK6767. As a specific measurement method, a plurality of plate-like test pieces of 5 cm in length and 5 cm in width are cut out from a polyolefin-based resin crosslinked foamed sheet, and a plurality of these test pieces are stacked in a thickness direction to form a laminate having a thickness of 25 cm. After producing and leaving at room temperature for 5 hours, 25% compressive strength of a laminated body is measured under normal temperature.
[0028]
Further, the average value of the 100% modulus at 160 ° C. of the polyolefin-based resin crosslinked foamed sheet and the average value of 100% modulus at 160 ° C. in the direction orthogonal to the direction of taking the maximum value of 100% modulus are small. The heat resistance of the polyolefin resin cross-linked foam sheet is reduced, and foam breaks and scratches are generated during molding. On the other hand, if the polyolefin resin cross-linked foam sheet is large, the flexibility of the polyolefin resin cross-linked foam sheet is lowered and the rigidity becomes too high. 9.8-19.6 N / cm ² It is limited to. The 100% modulus of the polyolefin-based resin crosslinked foamed sheet refers to 100% modulus measured in accordance with JISK6767.
[0029]
The specific value of the average value of the 100% modulus at 160 ° C. of the polyolefin resin crosslinked foamed sheet and the 100% modulus at 160 ° C. in the direction orthogonal to the direction of taking the maximum value of this 100% modulus. The measurement method is as follows.
[0030]
That is, polyolefin resin cross-linked foam sheet A of the same shape and size ₁ ~ A ₁₈ 18 sheets, each polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ Is left in a high-temperature box at 160 ° C. for 5 minutes to crosslink the polyolefin-based resin crosslinked foamed sheet A. ₁ ~ A ₁₈ Is maintained at the heating temperature during the measurement.
[0031]
Polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ When the thickness of the resin is 10 mm or less, the polyolefin resin crosslinked foamed sheet A is used as it is. ₁ ~ A ₁₈ When the thickness exceeds 10 mm, the polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ Is sliced to a thickness of 10 mm so as to completely include any one of the surfaces.
[0032]
And as shown in FIG. 1, each polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ Measurement center point B at any point on the surface ₁ ~ B ₁₈ It is determined. Polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ Measurement center point B ₁ ~ B ₁₈ Measurement center point B so that they are relatively at the same position ₁ ~ B ₁₈ Determine. Next, polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ The measurement center point B on the surface of ₁ ~ B ₁₈ Virtual reference line C passing through ₁ ~ C ₁₈ Each other, polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ Virtual reference line C ₁ ~ C ₁₈ Measurement center point B ₁ ~ B ₁₈ Draw in a state shifted by 10 ° clockwise around the center.
[0033]
In other words, any polyolefin resin cross-linked foam sheet (first sheet) A ₁ Virtual reference line (first virtual reference line) C ₁ The following polyolefin resin cross-linked foam sheet (second sheet) A ₂ First virtual reference line C ₁ To measurement center point B ₂ Virtual reference line (second virtual reference line) C in a state shifted by 10 ° clockwise around ₂ Draw. Furthermore, the following polyolefin resin cross-linked foam sheet (third sheet) A _Three Second virtual reference line C ₂ To measurement center point B _Three Virtual reference line (third virtual reference line) C in a state shifted by 10 ° clockwise around the center _Three Draw. By repeating this procedure, all polyolefin resin cross-linked foam sheets A ₁ ~ A ₁₈ Virtual reference line C one by one ₁ ~ C ₁₈ Draw.
[0034]
Next, each polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ From JIS K6251 4.1 (test piece shape and dimensions), the test piece D is punched by using the punching die specified in 4.4 (test piece punching blade type) in the dumbbell-shaped No. 1 type ( (See FIG. 2). At this time, the virtual folding line D when the specimen D is overlapped in the width direction. ₁ And the virtual reference line C ₁ ~ C ₁₈ And the virtual folding line D ₁ Midpoint D ₂ And measurement center point B ₁ ~ B ₁₈ So that they match.
[0035]
And each polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ 100% modulus is measured in accordance with JIS K6767 for each test piece D produced by punching from the above, and the maximum value of 100% modulus is extracted therefrom.
[0036]
Further, the 100% modulus of the test piece produced based on the virtual reference line shifted by 90 ° with respect to the virtual reference line of the test piece having the maximum 100% modulus is extracted, and the 100% modulus and 100% are extracted. The average value with the maximum modulus is calculated. This average value is the average value of the 100% modulus at 160 ° C. of the polyolefin resin crosslinked foamed sheet and the 100% modulus at 160 ° C. in the direction orthogonal to the direction of taking the maximum value of this 100% modulus. And
[0037]
When the polyolefin resin crosslinked foamed sheet is produced by extrusion foaming, the direction in which the 100% modulus in the polyolefin resin crosslinked foamed sheet takes the maximum value is the extrusion direction, and the maximum of 100% modulus The direction orthogonal to the direction in which the value is taken refers to a direction orthogonal to the extrusion direction and along the surface of the polyolefin-based resin crosslinked foamed sheet.
[0038]
In addition, since the balance between mechanical properties and moldability of the polyolefin resin crosslinked foamed sheet is excellent, the maximum value of the 100% modulus of the polyolefin resin crosslinked foamed sheet at 160 ° C. and the maximum value of this 100% modulus are At least one of 100% modulus at 160 ° C. in the direction orthogonal to the taking direction is 9.8 to 14.7 N / cm ² It is preferable that
[0039]
And if the average value of the maximum tensile strength of the polyolefin resin crosslinked foamed sheet at normal temperature and the tensile strength at normal temperature in the direction orthogonal to the direction of taking the maximum value of this tensile strength is small, the polyolefin resin The moldability of the cross-linked foamed sheet may be reduced, and foam breakage and scratches may occur during molding. If it is large, the flexibility of the polyolefin-based resin cross-linked foamed sheet is lowered and the rigidity becomes too strong, and the moldability is low. 117.6-245.0 N / cm ² Is preferred. In addition, the tensile strength of a polyolefin-type resin crosslinked foamed sheet means the tensile strength measured based on JISK6767.
[0040]
And, the specific measurement method of the average value of the tensile strength at room temperature in the direction orthogonal to the maximum value of the tensile strength at normal temperature of the polyolefin resin crosslinked foamed sheet and the direction of taking the maximum value of this tensile strength is as follows. Street.
[0041]
That is, 18 polyolefin resin cross-linked foam sheets of the same shape and size were prepared, and each polyolefin resin cross-linked foam sheet was allowed to stand at room temperature for 5 minutes. maintain.
[0042]
Polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ When the thickness of the resin is 10 mm or less, the polyolefin resin crosslinked foamed sheet A is used as it is. ₁ ~ A ₁₈ When the thickness exceeds 10 mm, the polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ Is sliced to a thickness of 10 mm so as to completely include any one of the surfaces.
[0043]
And as shown in FIG. 1, each polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ Measurement center point B at any point on the surface ₁ ~ B ₁₈ It is determined. Polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ Measurement center point B ₁ ~ B ₁₈ Measurement center point B so that they are relatively at the same position ₁ ~ B ₁₈ Determine.
[0044]
Next, polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ The measurement center point B on the surface of ₁ ~ B ₁₈ Virtual reference line C passing through ₁ ~ C ₁₈ Each other, polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ Virtual reference line C ₁ ~ C ₁₈ Measurement center point B ₁ ~ B ₁₈ Draw in a state shifted by 10 ° clockwise around the center.
[0045]
In other words, any polyolefin resin cross-linked foam sheet (first sheet) A ₁ Virtual reference line (first virtual reference line) C ₁ The following polyolefin resin cross-linked foam sheet (second sheet) A ₂ First virtual reference line C ₁ To measurement center point B ₂ Virtual reference line (second virtual reference line) C in a state shifted by 10 ° clockwise around ₂ Draw. Furthermore, the following polyolefin resin cross-linked foam sheet (third sheet) A _Three Second virtual reference line C ₂ To measurement center point B _Three Virtual reference line (third virtual reference line) C in a state shifted by 10 ° clockwise around the center _Three Draw. By repeating this procedure, all polyolefin resin cross-linked foam sheets A ₁ ~ A ₁₈ Virtual reference line C one by one ₁ ~ C ₁₈ Draw.
[0046]
Next, each polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ From JIS K6251 4.1 (test piece shape and dimensions), the test piece D is punched by using the punching die specified in 4.4 (test piece punching blade type) in the dumbbell-shaped No. 1 type ( (See FIG. 2). At this time, the virtual folding line D when the specimen D is overlapped in the width direction. ₁ And the virtual reference line C ₁ ~ C ₁₈ And the virtual folding line D ₁ Midpoint D ₂ And measurement center point B ₁ ~ B ₁₈ So that they match.
[0047]
And each polyolefin resin cross-linked foam sheet A ₁ ~ A ₁₈ Tensile strength is measured in accordance with JIS K6767 for each test piece D produced by punching, and the maximum value of the tensile strength is extracted from the tensile strength.
[0048]
Furthermore, the tensile strength of the test piece prepared based on the virtual reference line shifted by 90 ° with respect to the virtual reference line of the test piece having the maximum tensile strength is extracted, and the tensile strength and the maximum tensile strength are extracted. The average value with the value is calculated. This average value is defined as the average value of the maximum tensile strength of the polyolefin-based resin crosslinked foamed sheet at normal temperature and the tensile strength at normal temperature in the direction orthogonal to the direction of taking the maximum value of the tensile strength.
[0049]
When the polyolefin resin cross-linked foam sheet is produced by extrusion foaming, the direction in which the maximum value of the tensile strength at room temperature in the polyolefin resin cross-linked foam sheet is the extrusion direction, The direction orthogonal to the direction of taking the maximum value of strength refers to the direction orthogonal to the extrusion direction and along the surface of the polyolefin resin crosslinked foamed sheet.
[0050]
In addition, since the balance between mechanical properties and moldability of the polyolefin resin crosslinked foamed sheet is excellent, the maximum value of the tensile strength of the polyolefin resin crosslinked foamed sheet at normal temperature and the maximum value of this tensile strength are taken. At least one of the tensile strengths at normal temperature in the orthogonal direction is 117.6 to 196.0 N / cm ² It is more preferable that
[0051]
As a method for producing a polyolefin resin cross-linked foam sheet, a general-purpose foam production method is used. For example, (1) a foamable polyolefin resin composition comprising the above-described polyolefin resin and a thermally decomposable foaming agent is used. The foamable polyolefin resin sheet was prepared by adding a crosslinking aid as necessary, supplying the foamable polyolefin resin composition to an extruder, melt-kneading and extruding. After applying a predetermined amount of ionizing radiation to the resin-based resin sheet to give a cross-linked structure to the foamable polyolefin-based resin sheet, the cross-linked foamable polyolefin-based resin sheet is heated above the decomposition temperature of the above pyrolyzable foaming agent. And a method for producing a polyolefin resin crosslinked foamed sheet (ionizing radiation crosslinking method), (2) A foaming polyolefin resin composition comprising a decomposable foaming agent is added with a crosslinking agent and, if necessary, a crosslinking aid, and the foamable polyolefin resin composition is supplied to an extruder and melt-kneaded. A method for producing a polyolefin resin cross-linked foam sheet by extruding a foamable polyolefin resin sheet, and simultaneously heating the obtained foamable polyolefin resin sheet to a temperature equal to or higher than the decomposition temperature of the thermally decomposable foaming agent by a heating roll or the like. (Chemical cross-linking method) and the like, and any method may be adopted. Moreover, the said manufacturing method may be performed by the continuous process by an in-line, and may be performed by the division | segmentation process by an outline.
[0052]
The thermal decomposition type foaming agent is not particularly limited as long as it is a thermal decomposition type foaming agent that has been conventionally used in the production of foams. For example, azodicarbonamide, hydrazodicarbonamide, azodicarboxylic acid Barium salt, nitrosoguanidine, p, p'-oxybisbenzenesulfonyl semicarbazide, benzenesulfonyl hydrazide, N, N'-dinitrosopentamethylenetetramine, toluenesulfonyl hydrazide, 4,4-oxybis (benzenesulfonyl hydrazide), azobisiso Examples include butyronitrile, and azodicarbonamide is preferable. A thermal decomposition type foaming agent may be used independently, or 2 or more types may be used together.
[0053]
The addition amount of the pyrolytic foaming agent is not particularly limited, and is preferably 1 to 30 parts by weight, more preferably 1 to 14 parts by weight with respect to 100 parts by weight of the polyolefin resin.
[0054]
If the amount of the pyrolyzable foaming agent added to 100 parts by weight of the polyolefin resin is less than 1 part by weight, the polyolefin resin may not foam sufficiently, and if it exceeds 30 parts by weight, foam breakage may occur during foaming. It is because it becomes easy to raise | generate and it becomes impossible to obtain a desired polyolefin resin crosslinked foam sheet.
[0055]
The crosslinking agent is not particularly limited as long as it is a crosslinking agent that has been conventionally used in the production of foams. For example, isobutyl peroxide, dicumyl peroxide, 2,5-dimethyl-2 , 5-Di (t-butylperoxy) hexane-3,1,3-bis (t-butylperoxyisopropyl) benzene, t-butylcumyl peroxide, di-t-butyl peroxide, t-butylperoxy Benzoate, cyclohexane peroxide, 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 2,2-bis (t-butyl) Peroxy) octane, n-butyl-4,4-bis (t-butylperoxy) bellate, benzoyl peroxide, Ruperoxide, cumylperoxyneodecanate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyisopropyl carbonate, t-butylperoxyallyl carbonate, t-butylperoxyacetate 2,2-bis (t-butylperoxy) butane, di-t-butylperoxyisophthalate, t-butylperoxymaleic acid, and the like. A crosslinking agent may be used independently or 2 or more types may be used together.
[0056]
And the addition amount of the said crosslinking agent is although it does not specifically limit, 0.1-10 weight part is preferable with respect to 100 weight part of said polyolefin resin. This is because when the addition amount of the crosslinking agent relative to 100 parts by weight of the polyolefin resin is less than 0.1 parts by weight, the crosslinking density of the polyolefin resin becomes too low and the polyolefin resin is given a shear viscosity necessary for foaming. This is because the crosslink density of the polyolefin resin becomes too high and foaming may not be sufficiently achieved.
[0057]
The crosslinking aid is not particularly limited as long as it is a crosslinking aid conventionally used in the production of foams. For example, triallyl trimellitate, triallyl melittate, diallyl melittate , Diallyl phthalate, divinylbenzene, trimethylolpropane trimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, trimellitic acid triallyl ester, triallyl isocyanurate, ethyl vinylbenzene, neopentyl glycol Examples include dimethacrylate, 1,2,4-benzenetricarboxylic acid triallyl ester, 1,6-hexanediol dimethacrylate, and the like. The crosslinking aids may be used alone or in combination of two or more.
[0058]
And the addition amount of the said crosslinking adjuvant is although it does not specifically limit, 0.5-20 weight part is preferable with respect to 100 weight part of said polyolefin resin, and 2-10 weight part is more preferable.
[0059]
When the addition amount of the crosslinking aid relative to 100 parts by weight of the polyolefin resin is less than 0.5 parts by weight, the effect of adding the crosslinking aid may not be sufficiently obtained, and more than 20 parts by weight. This is because the crosslinking of the polyolefin resin proceeds too much and foaming may be hindered.
[0060]
Moreover, the gel fraction of a polyolefin-type resin crosslinked foamed sheet is mentioned as one standard of the addition amount of a crosslinking agent or a crosslinking adjuvant. That is, it is preferable to adjust the addition amount of a crosslinking agent or a crosslinking aid so that the gel fraction of the obtained polyolefin resin crosslinked foamed sheet is 20 to 75% by weight. It is more preferable to adjust the addition amount of the crosslinking agent and the crosslinking aid so that the amount becomes 35 to 70% by weight.
[0061]
The gel fraction referred to here is a test piece weighed (Ag) from a polyolefin-based resin crosslinked foamed sheet, and this test piece was immersed in 120 ° C. xylene for 24 hours, and then the residue (insoluble matter) was removed. The xylene solution is filtered through a 200-mesh wire mesh, the filtration residue (insoluble matter) on the wire mesh is vacuum dried, the dry residue (dried insoluble matter) is weighed (Bg), and the gel is calculated by the following formula Means fraction.
Gel fraction (% by weight) = 100 × (B / A)
[0062]
Among the methods for producing a polyolefin resin cross-linked foam sheet, as the ionizing radiation used in the ionizing radiation cross-linking method, particularly ionizing radiation that has been conventionally used for cross-linking of foamable resin compositions has been used. It is not limited, For example, an electron beam, an alpha ray, a beta ray, a gamma ray, an X ray etc. are mentioned. The ionizing radiation may be used alone or in combination of two or more.
[0063]
In the foamable polyolefin resin composition used in the present invention, for example, 2,6-di-t-butyl-p-cresol and the like may be used as long as the physical properties of the polyolefin resin crosslinked foamed sheet are not impaired. Phenol-based, phosphorus-based, amine-based, sulfur-based antioxidants such as dilaurylthiodipropionate (anti-aging agent), metal-benzoic acid-preventing agents such as methylbenzotriazole, phosphorus-based, nitrogen-based, halogen-based, Additives such as antimony and flame retardants such as mixtures thereof, inorganic fillers, organic fillers, lubricants, antistatic agents, and colorants (inorganic pigments and organic pigments) may be added. In addition, one type or two or more types of additives may be added.
[0064]
The polyolefin resin cross-linked foam sheet produced in this way is excellent in the balance of physical properties such as mechanical strength, heat resistance, flexibility, and elongation, and is obtained by a general-purpose molding method such as stamping molding or vacuum molding. The molded product of the present invention is formed into a desired shape by laminating and integrating the thermoplastic resin on one surface of the cross-linked resin-based foam sheet or by laminating and integrating the thermoplastic resin. In addition, in order to manufacture a molded article using a polyolefin resin cross-linked foamed sheet, it is preferable to use stamping molding.
[0065]
Here, the stamping molding is a method in which a polyolefin resin crosslinked foamed sheet is disposed in a cavity formed between a male and a male mold and a thermoplastic resin in a molten state is supplied into the cavity. This is a method in which a thermoplastic resin is laminated and integrated on one side of a polyolefin resin cross-linked foam sheet while forming a thermoplastic resin into a desired shape. By this stamping molding, one side of the polyolefin resin cross-linked foam sheet is thermoplastic. A molded product in which the resin is laminated and integrated and molded into a desired shape can be manufactured.
[0066]
An example of a specific procedure for stamping molding will be described in detail. After a dumpling-like or sheet-like thermoplastic resin is placed in a molten state in a female mold, a polyolefin-based resin cross-linked foam is formed on the thermoplastic resin. A sheet is disposed. In addition, the polyolefin resin crosslinked foamed sheet may or may not be heated. Thereafter, the male and female molds are closed, and the polyolefin resin cross-linked foam sheet and the thermoplastic resin are molded into a desired shape in the cavity formed between the male and male molds, and at the same time, the thermoplastic resin on one surface of the polyolefin resin cross-linked foam sheet. Can be laminated and integrated to produce a molded product.
[0067]
Examples of the thermoplastic resin include polyolefin resins such as polyethylene resins and polypropylene resins. Polyolefin resins may be used alone or in combination of two or more.
[0068]
Examples of the polyethylene-based resin include, for example, ultra-low density polyethylene, low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, and the like, ethylene containing 50% by weight or more of ethylene and a polymerizable monomer And a copolymer thereof. Polyethylene resins may be used alone or in combination of two or more.
[0069]
Examples of the polymerizable monomer copolymerizable with ethylene include α-olefins such as propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene and 1-octene. Vinyl acetate, acrylic acid, methacrylic acid, acrylic ester, methacrylic ester and the like. A polymerizable monomer may be used independently or 2 or more types may be used together.
[0070]
Furthermore, examples of the polypropylene resin include a propylene homopolymer, a copolymer of propylene and a polymerizable monomer containing 50% by weight or more of propylene, and the like. Polypropylene resins may be used alone or in combination of two or more.
[0071]
Examples of the polymerizable monomer copolymerizable with propylene include α-, such as ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, and 1-octene. Examples include olefins. The polymerizable monomer copolymerizable with propylene may be used alone or in combination of two or more.
[0072]
In addition, additives such as inorganic compounds such as talc, silicic acid and calcium carbonate, thermal stabilizers, antioxidants, nucleating agents, colorants and the like are added to the thermoplastic resin as long as the physical properties are not impaired. May be.
[0073]
Further, a resin other than a polyolefin resin such as an ABS resin, a polystyrene resin, or a petroleum resin may be added to the thermoplastic resin, and the thermoplastic resin may be foamed or crosslinked. Good.
[0074]
And the skin material may be laminated and integrated on the other surface of the polyolefin-based resin crosslinked foamed sheet. As described above, in the case where the skin material is laminated and integrated on the other surface of the polyolefin-based resin crosslinked foamed sheet, the skin material is previously laminated and integrated on the other surface of the polyolefin-based resin crosslinked foamed sheet before stamping molding. Alternatively, a skin material may be laminated on the other surface of the polyolefin resin cross-linked foam sheet in a separable manner, and the skin material may be laminated and integrated on the other surface of the polyolefin resin cross-linked foam sheet during stamping molding. .
[0075]
Examples of the skin material include a polyvinyl chloride sheet, a sheet made of a mixed resin of polyvinyl chloride and ABS resin, a thermoplastic elastomer sheet, a woven fabric, a knitted fabric, and a non-woven fabric.
[0076]
When the polyolefin resin cross-linked foam sheet is formed by vacuum forming, a thermoplastic resin is laminated and integrated on one surface of the polyolefin resin cross-linked foam sheet, and if necessary, other polyolefin resin cross-linked foam sheets can be used. After the surface material is laminated and integrated on the surface, the polyolefin-based resin cross-linked foam sheet and the thermoplastic resin, and if necessary, the surface material is heated to a predetermined temperature and vacuum molded to form a desired shape. .
[0077]
[Action]
The polyolefin-based resin crosslinked foamed sheet in the molded article of the present invention comprises a polyolefin-based resin in which at least one of melting endothermic peak temperatures by differential scanning calorimetry is 140 ° C. or higher, apparent density, 25% compressive strength at room temperature, And the average value of the maximum value of 100% modulus at 160 ° C. and the 100% modulus at 160 ° C. in the direction orthogonal to the direction taking the maximum value of 100% modulus is limited to a predetermined range. It has an excellent balance of physical properties such as mechanical strength, heat resistance, flexibility and elongation, and is suitable for general-purpose molding methods, particularly stamping molding, and can be accurately molded into complicated shapes. Therefore, a molded product using this polyolefin resin crosslinked foamed sheet can be beautiful and have a complicated shape.
[0078]
Further, the polyolefin resin crosslinked foamed sheet in the molded product of the present invention has an average value of the maximum tensile strength at room temperature and the tensile strength at room temperature in the direction orthogonal to the direction of taking the maximum value of the tensile strength. Since it is limited within a predetermined range, it is excellent in stamping moldability and can be accurately molded into a complicated shape. Therefore, a molded article using this polyolefin-based resin crosslinked foamed sheet can be more beautiful and have a complicated shape.
[0079]
【Example】
(Examples 1-3, Comparative Examples 1-5)
Linear low density polyethylene having a melting endothermic peak temperature of 120 ° C. by differential scanning calorimetry (density: 0.92 g / cm ^Three , Bending elastic modulus: 294 MPa, melt flow rate at 230 ° C .: 2 g / 10 min), propylene homopolymer having a melting endothermic peak temperature of 164 ° C. by differential scanning calorimetry (density: 0.90 g / cm) ^Three , Bending elastic modulus: 1960 MPa, melt flow rate at 230 ° C .: 14 g / 10 min) and thermoplastic polyolefin elastomer having a melting endothermic peak temperature of 143 ° C. by differential scanning calorimetry (density: 0.88 g / cm) ^Three , Flexural modulus: 83.3 MPa, melt flow rate at 230 °: 0.45 g / 10 min), azodicarbonamide as a pyrolytic foaming agent, and trimethylolpropane trimethacrylate as a crosslinking aid Further, 2,6-di-t-butyl-p-cresol and dilauryl thiodipropionate were added in predetermined amounts as shown in Table 1 as antioxidants to prepare foamable polyolefin resin compositions.
[0080]
Next, the foamable polyolefin resin composition was supplied to a twin screw extruder and extruded at a resin temperature of 190 ° C. to obtain a foamable polyolefin resin sheet having a thickness of 1.5 mm.
[0081]
Subsequently, the foamable polyolefin resin sheet was cross-linked by irradiating an electron beam of 3.5 Mrad at an acceleration voltage of 800 kV on both sides and then foamed by heating at 250 ° C. for 5 minutes to give a polyolefin resin having a thickness of 3 mm. A crosslinked foamed sheet was produced.
[0082]
The apparent density of the polyolefin resin cross-linked foam sheet obtained as described above, 25% compressive strength at room temperature, the maximum value of 100% modulus at 160 ° C. and the direction orthogonal to the direction of taking the maximum value of this 100% modulus The average value of 100% modulus at 160 ° C. (average value of 100% modulus at 160 ° C.), and the normal value in the direction orthogonal to the direction of taking the maximum value of the tensile strength and the maximum value of the tensile strength at normal temperature Table 1 shows the average value (tensile strength average value at room temperature) with the tensile strength at.
[0083]
Next, a soft polyvinyl chloride sheet having a thickness of 0.50 mm was adhered and integrated all over the upper surface of the polyolefin-based resin crosslinked foamed sheet via a polyester-based adhesive.
[0084]
Then, a planar square plate having a length of 15 cm, a width of 15 cm, and a thickness of 3.5 mm was cut out from the polyolefin-based resin-crosslinked foamed sheet in which the soft polyvinyl chloride sheet was integrally bonded to the upper surface.
[0085]
Next, the plate-like body is disposed between the male and female molds in the mold open state so that the soft polyvinyl chloride sheet is on the male mold side, and a 200 ° C. polypropylene resin (at 230 ° C. in the female mold). After feeding 20 g (melt flow rate: 20 g / 10 min), the male and female molds were immediately closed at a pressure of 4.9 MPa for 5 seconds, and then the male and female molds were closed at a pressure of 0.98 MPa for 50 seconds.
[0086]
After that, water is passed through the male and female molds to cool the polyolefin resin crosslinked foamed sheet, and then the male and female molds are opened. Polypropylene resin is spread on one side of the polyolefin resin crosslinked foamed sheet and soft polychlorinated on the other side. A molded product in which vinyl sheets were laminated and integrated was obtained. The molded product is formed in a bottomed cylindrical shape in which a cylindrical peripheral wall portion having a thickness of 2 mm extends vertically upward from an outer peripheral edge of a flat circular bottom surface portion having a diameter of 8 cm and a thickness of 3.5 mm. It was.
[0087]
The appearance and flexibility of the molded product obtained as described above were evaluated according to the following criteria, and the results are shown in Table 1.
[0088]
(Appearance)
The surface of the obtained molded product was visually observed, and the appearance was evaluated according to the following criteria.
(Bottom)
○ The surface of the soft polyvinyl chloride sheet on the bottom was excellent with no irregularities or wrinkles.
X: Unevenness and wrinkles occurred on the soft polyvinyl chloride sheet portion on the bottom, and the appearance was poor.
[Corner]
○ The outer surface of the soft polyvinyl chloride sheet portion at the connecting portion of the bottom surface portion and the peripheral wall portion did not break and had an excellent appearance.
X: The soft polyvinyl chloride sheet portion at the connecting portion of the bottom surface portion and the peripheral wall portion was torn and the appearance was poor.
[0089]
(Flexibility)
The hardness of the soft polyvinyl chloride sheet portion of the obtained molded product was measured using an Asker C type hardness meter, and the flexibility was evaluated according to the following criteria.
[Criteria]
○ The hardness was 59 or less.
X The hardness was 60 or more.
[0090]
[Table 1]

[0091]
As described above, the polyolefin resin crosslinked foamed sheet in the molded article of the present invention is composed of a polyolefin resin in which at least one of melting endothermic peak temperatures by differential scanning calorimetry is 140 ° C. or higher, and the apparent density is 0. .40-0.200 g / cm ^Three And 25% compressive strength at room temperature is 0.98 to 9.80 N / cm ² The average value of the maximum value of 100% modulus at 160 ° C. and the 100% modulus at 160 ° C. in the direction orthogonal to the direction taking the maximum value of 100% modulus is 9.8 to 19.6 N / Cm ² Therefore, it is excellent in the balance of physical properties such as mechanical strength, heat resistance, flexibility and elongation, and is excellent in moldability. The foamed sheet has excellent appearance without tearing, etc., and has excellent flexibility and tactile feel, has almost accurate dimensions, and is suitable as a molded product having a complicated shape such as a vehicle interior material. Can be used.
[0092]
And in the polyolefin-based resin crosslinked foamed sheet in the molded article of the present invention, the average value of the maximum tensile strength at normal temperature and the tensile strength at normal temperature in the direction orthogonal to the direction of taking the maximum value of this tensile strength 117.6-245.0 N / cm ² In this case, the molded product using the polyolefin resin cross-linked foamed sheet has wrinkles and irregularities on the skin material, which is further excellent in the balance of physical properties such as mechanical strength, heat resistance, flexibility and elongation, and moldability. In addition to having excellent appearance with almost no appearance, it has excellent flexibility and can be suitably used for applications that require high appearance and tactile sensation.
[Brief description of the drawings]
FIG. 1 shows the maximum value of 100% modulus at 160 ° C. in a polyolefin resin cross-linked foam sheet, and the 100% modulus at 160 ° C. in a direction orthogonal to the direction of taking the maximum value of 100% modulus. Of specimens used for measuring the average value of the tensile strength at normal temperature and the average value of tensile strength at normal temperature in the direction orthogonal to the direction of taking the maximum value of tensile strength It is the top view which showed the point.
FIG. 2 is a plan view showing the test piece.
[Explanation of symbols]
A ₁ ~ A ₁₈ Polyolefin resin cross-linked foam sheet
D Test piece

Claims (2)

It consists of 10 to 50% by weight of a polyethylene resin, 10 to 40% by weight of a polypropylene homopolymer, and 20 to 50% by weight of a thermoplastic olefin elastomer , and at least one of melting endothermic peak temperatures by differential scanning calorimetry is 140 ° C. or higher. And an apparent density of 0.040 to 0.200 g / cm ³ , a 25% compressive strength at room temperature of 0.98 to 9.80 N / cm ² , and 100 at 160 ° C. Polyolefin-based resin cross-linking having an average value of 9.8 to 19.6 N / cm ² between the maximum value of% modulus and the 100% modulus at 160 ° C. in the direction orthogonal to the direction of taking the maximum value of 100% modulus A thermoplastic resin layered and integrated on one surface of a foam sheet, and then molded into a desired shape. Goods.  2. The molded article according to claim 1, wherein a skin material is laminated and integrated on the other surface of the polyolefin-based resin crosslinked foamed sheet, and then molded into a desired shape.

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