JPH01222929A - Polyolefin-based resin foam for laminating skin material, manufacture thereof and composite material used therewith - Google Patents

Abstract

PURPOSE:To reduce the entrainment of air and enable the lamination of skin material by a method wherein the foam concerned is compressed under heat so as to have the apparent density, gel percentage and surface roughness with the predetermined values respectively and to contain bubbles, the length in the direction of the thickness of each of which is the predetermined percentage of the length in the direction normal to the direction of the thickness. CONSTITUTION:The foam concerned is compressed under heat so as to have the apparent density of 0.20-0.025g/cc, the gel percentage of 0.5-75% and the absolute value of surface roughness is 15mum or less and to contain bubbles, the length in the direction of the thickness of each of which is 10-50% of the length in the direction normal to the direction of the thickness when seen in longitudinal section. As polyolefin-based resin foam, polyethylene resin, the density of which is 0.987-0.955g/cc and the melt index of which is 0.5-50, polyethylene resin, which is produced by copolymerize monomers of acrylate and the like, or the like is employed. As the manufacture of polyolefin-based resin foam, the method by heat decomposition type foaming agent or the method called extrusion foaming will do and, further, any method, which is publicly known and by which crosslinked polyolefin-based resin foam is manufactured, also will be used.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a polyolefin resin foam for laminating a skin material, which is used for molded interiors of vehicles such as automobiles, by laminating a skin material. This invention relates to a manufacturing method and a composite material using the same.

[Prior Art] This type of polyolefin resin foam is made into a composite material by laminating a skin material such as a soft vinyl chloride sheet on its surface using an adhesive method or an extruder (see Figure 1).
The composite material thus obtained is placed on an aggregate such as a polypropylene resin sheet that has been heated with an infrared heater or the like to form a molten layer, and is pressed in that state.
Automotive interior molded products of desired shapes can now be obtained.

[Problem to be solved by the invention] However, the surface of the polyolefin resin foam,
It has an uneven structure due to its cell structure, and when the skin material mentioned above is laminated, air is drawn in between the skin material and the air that is drawn in expands during the heat molding process, causing the weakest part to As the bubbles concentrate, the bubbles break down and become connected to each other, forming large bubbles and causing cracks, resulting in a phenomenon called blistering, which reduces the quality of automotive interior molded products and produces defective products. was there.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polyolefin resin foam that can be laminated with a skin material with less air entrainment.

[Means for Solving the Problems] In order to achieve the above object, the polyolefin resin foam for skin material laminate according to the present invention has an apparent density of 0.20 to 0.025 g/cc and a gel content of 0.20 to 0.025 g/cc. rate is 0.5
~75%, and the absolute value of the surface roughness is 15μ or less, and the length in the thickness direction is 10 to 50% of the length in the direction perpendicular to the thickness direction in longitudinal section view.
It is characterized by being heated and compressed to contain % of air bubbles.

As a polyolefin resin foam, the density is 0°897.
-0.955g/cc, M I 0.5-50 polyethylene resin, polyethylene resin copolymerized with ethylene and a heptamer such as α-olefin, vinyl acetate, acrylic acid, acrylic ester, etc. 0 ethylene
．． 5 to 35%, random or block or random-block copolymerized polypropylene resin, or a foam made of a mixture of such polypropylene resin and polyethylene resin or copolymerized polyethylene resin is applicable. can.

As a method for manufacturing polyolefin resin foam,
It may be one using a pyrolytic foaming agent, or it may be produced by a method called extrusion foaming, which is obtained by kneading a liquid and a polyolefin resin in an extruder and gasifying the liquid. Any method may be used as long as it produces a polyolefin resin foam.

A particularly preferred method is to crosslink a mixture consisting of a polyolefin resin, a blowing agent, and a crosslinking accelerator with ionizing radiation;
Thereafter, a method of foaming by heating above the decomposition temperature of the blowing agent, or a method of foaming by heating the blowing agent to a temperature higher than the decomposition temperature of the blowing agent, or a method of heating a mixture consisting of a polyolefin resin, a blowing agent, an organic peroxide, a crosslinking accelerator, and in some cases a crosslinking regulator, and adding an organic peroxide and Examples include a method of heating the foaming agent to a temperature higher than its decomposition temperature to effect crosslinking and foaming.

These methods are suitable for producing endless continuous sheet foams.

The resin used for the polyolefin resin foam may be propylene homopolymer, but ethylene, butene, etc.
A polypropylene resin containing 1 to 30% by weight of α-olefin and copolymerized in a random or random-block form, such as No. 1, is preferably used.

Other resins may be mixed with these resins as long as they do not adversely affect the foam.For example, low density, medium density or high density polyethylene, polyethylene copolymer copolymerized with α-olefin, Alternatively, a copolymer containing ethylene as a main component and vinyl acetate or acrylic ester may be mixed.

As the blowing agent, any compound that is liquid or solid at room temperature and that decomposes or vaporizes when heated above the melting point of the polyolefin resin can be used as long as it does not substantially interfere with sheet formation or crosslinking reactions. , the decomposition temperature is 1
Preferably, the temperature is in the range of 80 to 240°C, and specific examples include azodicarbonamide, azodicarboxylic acid metal salts, and dinitrosopentamethylenetetramine.

These blowing agents have a ratio of 0.1 to polypropylene resin.
It is used in the range of ~40% by weight, and the mixing amount can be changed arbitrarily depending on the type and expansion ratio.

When an organic peroxide is used in the crosslinking reaction, the decomposition temperature is approximately 120° when the boiling point is higher than the flow start temperature of the polyolefin resin used in the present invention and the decomposition half-life is 1 minute.
The temperature is preferably 150°C or higher, particularly preferably 150°C or higher. Specific examples include methyl ethyl ketone peroxide (182°C), L-butylperoxyisopropyl carbonate (153°C), and dicumyl peroxide (171"C). These organic peroxides are 0.01-1 for resin
0% by weight, preferably 0.05 to 5% by weight.

Typical examples of crosslinking accelerators include divinylbenzene,
Diallylbenzene, divinylnaphthalene, etc. are included, and the preferable amount of addition thereof is 0.00% relative to the polyolefin resin.
It is 1 to 30% by weight, more preferably 0.3 to 20% by weight.

The polyolefin resin, the blowing agent, the crosslinking accelerator, and the organic peroxide can be mixed by a conventionally known mixing method. Examples include mixing with a Henschel mixer, mixing with a Panbury mixer, mixing with a mixing roll, mixing with a kneading extruder, and immersing polypropylene resin in a solution containing a blowing agent, a crosslinking accelerator, and an organic peroxide. Used in combination. Particularly when the resin is in powder form, powder mixing using a Henschel mixer is convenient. Powder mixing is typically performed between room temperature and the resin's softening temperature, and melt mixing is typically performed between the resin's melting temperature and 185°C.
It is carried out in the range of °C.

When producing a foam in the form of a continuous sheet, it is desirable to form the foam into a sheet by extrusion at a temperature below the decomposition temperature of the foam.

Crosslinking and foaming of the uniformly mixed or kneaded foam composition using an organic peroxide is carried out by heating in the temperature range of 130 to 300°C, preferably 150 to 260°C, under normal pressure or pressure. Can be done. If crosslinking and decomposition of the foaming agent occur almost simultaneously during heating, a method is used in which the mold is heated for the time necessary for crosslinking and foaming in a pressure-sealable mold, and the pressure is removed and foaming is simultaneously performed. This method is extremely effective when foaming a powder mixture as it is.

If the foaming agent does not decompose under heat crosslinking conditions, a method is used in which after crosslinking, the foaming agent is heated at normal pressure or under increased pressure at a temperature equal to or higher than the decomposition temperature of the foaming agent.

In particular, in order to obtain a foam with fine cells, it is preferable to foam under pressure.The heating time required for crosslinking and foaming varies depending on the composition heating temperature, the thickness of the material to be foamed, etc., but is usually 1 to 30 minutes. It's a minute.

When crosslinking the foamable composition by irradiating it with ionizing radiation, the ionizing radiation includes electron beams from an electron beam accelerator such as Co, α, β,
T-rays are preferred, but X-rays and ultraviolet rays may also be used. The dose of these radiations varies depending on the type of crosslinking accelerator and the desired crosslinking ratio, but is generally 0.1 to 30 Mrad.
, preferably 0.5 to 20 Mrad.

Foaming of the radiation-crosslinked resin in this manner may be carried out under normal pressure, increased pressure, or reduced pressure as long as the method involves heating the polypropylene resin to a temperature higher than its melting temperature, preferably 190°C; As in the case described above, any source or heating medium can be used depending on the shape of the unfoamed molded product and the pressure state during foaming.

As a means of heating polyolefin resin foam,
Hot air, infrared heaters, steam heating, and ultrasonic heating can be used as known means. The heating temperature is determined by differential scanning calorimetry (DS) of the resin constituting the polyolefin resin foam.
C).

The skin material to be laminated to the polyolefin resin foam of the present invention may include fabrics made of natural or artificial fibers,
Known materials such as a sheet made of vinyl chloride resin, a thermoplastic elastomer sheet, and leather can be used.

Note that the gel fraction of the polyolefin resin foam refers to a value measured as follows.

First, the foam is cut into about 100 square meters, approximately 0.05 g of O, Ig is collected, and this is accurately weighed as a sample, and its weight is A(
g).

This sample is heated in tetralin at a temperature of 130'C for 3 hours, then cooled, washed with acetone and then water to remove the eluted bone, and then dried.

The dried sample is accurately weighed and its weight is defined as B (g).

The gel fraction (%) is calculated using the following formula.

Gel fraction (%) = B/AX 100 If the apparent density exceeds 0.20 g/cc, it will be too hard, and if the apparent density is 0.025 g/cc, the strength of the material will decrease. I will do it.

In addition, if the gel fraction is less than 0.5%, the resin will be in a non-crosslinked state and the heat resistance will decrease, and if the gel fraction exceeds 75%, moldability will deteriorate. .

In addition, if the absolute value of the surface roughness, that is, the distance from the tip of the most protruding top to the bottom of the deepest valley in the unevenness of the surface of the polyolefin resin foam, exceeds 15 μm, the surface roughness may deteriorate when laminating the surface material. Air will be trapped between the material and the material.

Furthermore, if the length of the bubbles contained in the polyolefin resin foam in the thickness direction is less than 10% of the length in the direction perpendicular to the thickness direction when viewed in longitudinal section, the strength will decrease; If it exceeds 50%, it becomes difficult to bend and flexibility decreases.

The polyolefin resin foam of the present invention has an apparent density of 0.
．． 20-0.0258/cc, gel fraction 0.5-7
By heating a 5% polyolefin resin foam and compressing the polyolefin resin foam by passing it between pressure rolls set at a clearance of 25 to 75% of the thickness of the polyolefin resin foam, a good result can be obtained. can be manufactured. In order to keep the surface roughness within a predetermined range, conditions for heating and compression processing may be appropriately selected depending on the foam used as a raw material.

[Function] Polyolefin resin foam is heated and compressed to reduce surface irregularities and deform the bubbles contained therein to increase flexibility.

[Example] Disaster ■ Radiation-crosslinked polypropylene resin foam l with a foaming ratio of 20 times, 25 times, and 30 times, a thickness of Stm product, and a gel fraction of 37% was prepared as shown in Fig. 1. As shown in the schematic process diagram, it is heated with an infrared heater 2 so that its surface temperature is 100-120°C, and the clearance is 1.5 m.
(50%) by a pressure roll 3.3 and then cooled by a cooling roll 4.4.

The surface temperature of the foam that has passed through the cooling rolls 4, 4 is 30~
The temperature has dropped to 40°C, there is no residual strain in the foam that causes warping, the thickness after treatment is 2.0 m, the surface is excellent in smoothness, and each magnification product is made of polypropylene resin. A very moist and flexible foam was obtained without the stiff feel peculiar to foam.

A skin material 5 was bonded to the surface (non-heated surface) of the thus obtained radiation-crosslinked polypropylene resin foam using a two-component polyester adhesive to form a composite. Desmodur R was used as a curing agent.

Next, we added 22 polypropylene resin sheets that will become the aggregate.
Extrude at 0°C and reduce thickness to 2.5mm with polygingerol.
5 trm to reduce irregularities on the sheet surface, and the composite material with the skin material pasted was inserted using subsequent rolls, and the composite material with the skin material attached was pressed together with the polypropylene resin sheet and continuously fused.

Comparison of static spots Using the same polypropylene resin foam as in the previous example, without the heat compression treatment,
The skin material was laminated and the aggregate was fused.

For each of the above Examples and Comparative Examples, the surface roughness in the direction perpendicular to the longitudinal direction of the polypropylene resin foam was measured using a measuring device (Model 5E-3E: manufactured by Kosaka Institute Co., Ltd.) with a diameter of 0.8M. The results were measured using a sensor with 200 times the sensitivity.
b) [Example] and the results shown in the following table were obtained.

Furthermore, when the flexibility (compression hardness) was measured, the results shown in the following table were obtained.

Regarding this flexibility, according to JIS K6767,
Cut the polypropylene resin foam into 5% 5cm pieces and cut several of them into pieces with a height of approximately 2011I1.
The force required per cii to compress it by 25% was measured.

Furthermore, the presence or absence of blistering due to air entrainment was examined, and the results shown in Table 1 were obtained.

Table 1: Blistering under heating for main molding From the above results, it can be seen that according to the examples of the present invention, the surface irregularities are small, the surface is highly flexible, and there is no blistering, and high quality heat-molded products can be easily scraped. It was clear that this could be achieved.

In addition, the foaming ratio of each of the above comparative examples and examples was 2.
When the shape of bubbles contained in the 0x product was photographed using an electron microscope, the results shown in FIGS. 4 and 5 were obtained.

FIG. 4(a) is a vertical cross-sectional photograph of a polypropylene resin foam of a comparative example cut along the longitudinal direction, and FIG. 4(b) is a photograph of the same longitudinal cross-section of an example. A side view photograph, (a) of FIG. 5 is a cross-sectional view photograph of a portion of a polypropylene resin foam of a comparative example cut along a plane in the width direction perpendicular to the longitudinal direction, and (b) of FIG. is a cross-sectional photograph of an example.

Based on the above results, the ratio between the length in the short axis direction and the length in the long axis direction of 15 to 20 bubbles in the longitudinal section and the cross section of the comparative example and the example (unit: 2%)
, take the average value, and then calculate the 25x product and 30x product.
When average values were similarly taken for the polypropylene resin foams of each of the products, the results shown in Table 2 were obtained.

(Hereinafter, blank spaces) Table 2 According to this table, the bubbles in the example were flattened compared to the comparative example in both longitudinal and cross-sectional views, and it was found that the examples exhibited good flexibility. it is obvious.

[Effects of the Invention] According to the polyolefin resin foam for skin material laminate according to the present invention, it has sufficient strength, is highly flexible, and has small irregularities on the surface to which the skin material is bonded, so it can be used as a skin material. When laminating the skin materials to obtain a composite material, it can be heated and molded without causing blisters due to the expansion of the trapped air. It is possible to provide a polyolefin resin foam for skin material laminate that is excellent in obtaining composite materials to be applied.

In addition, the obtained composite material has a good appearance without cracks caused by blistering, and both product yield and quality can be improved.

[Brief explanation of the drawing]

The drawings show an example of the polyolefin resin foam for skin material laminate according to the present invention, FIG. 1 is a diagram showing a schematic process of heat compression of polypropylene resin foam and skin material lamination, and FIG. The cross-sectional view of the material, FIG. 3, is a diagram showing the unevenness change on the surface of the polypropylene resin foam. l...Polypropylene resin foam 2...Infrared heater 3...Crimping roll application Daitoshi Co., Ltd. Agent Patent Attorney Tsutomu Sugitani Figure 1 Figure 3 (a) (b) Note Figures 4 and 5 are electron microscope images of the comparative example and the example in longitudinal and cross-sectional views, respectively. A photograph is shown. E June 17, 1988 Patent Application No. 49340 ≦ 2. Name of the invention Polyolefin resin foam for skin material laminate, manufacturing method thereof, and composite material using the same 3. Amendment Relationship with the case of the person who filed the patent application Address of the patent applicant 2-2-1 Nihonbashi Muromachi, Chuo-ku, Tokyo Name (
315) Azuma Co., Ltd. Representative: Katsunosuke Maeda 4, Agent address: 11 Nishitenma, 1-10-8 Nishitenma, Kita-ku, Osaka
Matsuya Building 6, number of claims increased due to amendment (none) 7,
In the column for a brief description of the drawings in the specification to be amended, Insert "An enlarged vertical cross-sectional view of the main parts, and Figure 5 is an enlarged cross-sectional view of the main parts." (2) Correct each of Figures 4 and 5 as shown in the attached sheet. ], List of attached documents ( 1) Corrected drawing 1 letter June 17, 1988 20 Name of the invention Polyolefin resin foam for skin material laminate, its manufacturing method and composite material using the same 3 Person making the amendment Relationship to the case Patent applicant Address 2-2-1 Nihonbashi Muromachi, Chuo-ku, Tokyo Name
(315) Azuma Co., Ltd. Representative: Katsunosuke Maeda 4, Agent address: 11 Nishitenma, 1-10-8 Nishitenma, Kita-ku, Osaka
Matsuya Building 6, number of claims increased due to amendment (none) 7,
Column 8 of Detailed Description of the Invention in the Specification Subject to Amendment, Contents of the Amendment (1) In the second line from the bottom of page 15 of the specification, "Longitudinal cross-sectional photograph, J" is replaced with "Main part showing the condition. Corrected to "Enlarged vertical cross-sectional view." (2) “Longitudinal cross-sectional photograph of the same,” in the first line from the bottom of page 15,
” is corrected to r amount enlarged longitudinal cross-sectional view, 1. (3) In the second and third lines from the top of page 16, ``Cross-sectional photograph, j'' is corrected to ``Enlarged cross-sectional view of the main part showing the condition.'' (4) In the 3rd to 4th lines from the top of page 16, ``Transverse cross-sectional photograph'' is corrected to ``R-open enlarged cross-sectional view''.

Claims (2)

[Claims] (1) Apparent density is 0.20 to 0.025 g/cc, gel fraction is 0.5 to 75%, and absolute value of surface roughness is 1
A skin material characterized by being heated and compressed so as to have a diameter of 5 μm or less and to contain air bubbles whose length in the thickness direction is 10 to 50% of the length in the direction perpendicular to the thickness direction when viewed in longitudinal section. Polyolefin resin foam for lamination. (2) Heating a polyolefin resin foam with an apparent density of 0.20 to 0.025 g/cc and a gel fraction of 0.5 to 75%, 1. A method for producing a polyolefin resin foam for skin material laminate, which comprises compressing it through pressure rolls set at a clearance of 25 to 75% of the body thickness. (3) A composite material formed by adhering a skin material to the polyolefin resin foam for skin material laminate described in item (1).