JPS60166449A - Multilayer sheet made of polypropylene - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention The present invention has a foaming ratio of 2.5 times or less, a foamed layer with fine foamed cells and a uniform foamed layer, and both or one side of the foamed layer is covered with a non-foamed layer made of polypropylene. The present invention relates to a polypropylene multilayer sheet.

Generally, multilayer sheets made by laminating two or more types of plastics are used as sheet materials that have various properties such as heat resistance, abrasion resistance, chemical resistance, and aging resistance. One layer of this multilayer sheet is often a foamed multilayer sheet material with at least a foam layer, and these foamed multilayer sheets exhibit the properties of the foam layer, such as lightness, heat insulation, and cushioning properties, and have - To compensate for the decrease in strength due to foaming, it is used as an excellent structural material that maintains mechanical strength by laminating non-foamed layers.

More specifically, by taking advantage of the properties of polypropylene sheets such as impact resistance, heat resistance, chemical resistance, and aging resistance, they can be used as automobile interior materials or home appliance parts materials, as well as their light weight and heat insulation properties. It is widely applied. For these uses, it is necessary to maintain the rigidity and heat resistance of the foam layer as much as possible, and in the present invention, it is essential to add a filler to polypropylene to control the rigidity and heat resistance. These multilayer sheets are manufactured by the method exemplified in, for example, Japanese Patent Application Laid-Open No. 50-55688. Normally, when manufacturing a multilayer sheet having a foam layer made of polypropylene with a relatively low magnification, the foam layer is formed by adding a predetermined amount of a pyrolyzable chemical foaming agent to polypropylene in advance, and heating and melting the polypropylene. However, since foaming layers are usually made from polypropylene pellets containing fillers with finely divided foaming agents added, they can be easily classified during the feeding process from the hopper to the cylinder, and the foaming agent can be dispersed in the molten plasticized material. As a result, the foaming becomes non-uniform and a homogeneous molded product cannot be obtained. In the multilayer sheet of the present invention, uniform foaming of the foam layer is the key point. The reality is that sheet manufacturing is difficult.

As a result of intensive studies, the present inventors found that a homogeneous mixture of granular polypropylene for molding and a foaming agent, in which a filler is attached to the surface of granular polypropylene using a binder, or a foaming agent and a filler bonded to the surface of granular polypropylene, When granular polypropylene for foam molding attached with a foaming agent is used as a raw material for forming a foam layer in a multilayer sheet, the foam layer foams uniformly,
It has been found that the surface coated with the non-foamed layer is also smooth and has sufficient commercial value. That is, in the present invention, the foaming ratio is 2.
．． 5 times or less, has a foam layer with fine foam cells and is uniform, and both or one side of the foam layer is made of polypropylene.
This relates to a polypropylene multilayer sheet coated with ftJ, and the raw material for forming the foam layer has a bulk specific gravity of 0.45 or more and an average particle size of 150 to 2000 E
A homogeneous mixture of a blowing agent and a granular polypropylene for molding having at least one layer of a filler and a binder on the surface of the granular polypropylene; The foam molding JT having at least one layer is made of one granular polypropylene.

The present invention will be explained in detail below.

In the present invention, the granular polypropylene for molding and the granular polypropylene for foam molding used as raw materials for forming 1 m of foam have a length of 19 m. Manufactured based on the method described.

The granular polypropylene used in the present invention includes propylene homopolymers and propylene and other α-
These polyolefins are random copolymers and block copolymers with olefins, and preferably these polyolefins are crystalline and have a bulk specific gravity of 0.45 or more and an average particle size of 150.
~2000j chron. If the bulk specific gravity is less than 0.45, it is not preferable because there are many voids inside the grains and between the grains and sufficient deaeration cannot be carried out during molding. If the particle size is too small, it becomes easy to scatter, and especially if the particle size is less than 100 microns, it becomes easy to cause a dust explosion, which is not preferable. −
However, if the particle size is too large, the dispersion of the blowing agent and filler in the resulting molded product will be poor. Furthermore, the closer the shape of the granular polypropylene is to a spherical shape and the narrower the particle size distribution, the more preferable it is. The shape is basically determined by the polymerization catalyst used during its production.

As an example of producing polypropylene with preferable properties suitable for the present invention, a titanium trichloride composition obtained by reducing titanium tetrachloride with an organoaluminum compound and further activating the polymer is shown. propylene or propylene and other olefins in an inert solvent, or in an excess of liquid propylene in the substantial absence of an inert common medium, using a catalyst system consisting of an organoaluminum compound and optionally an electron-donating compound. Obtained by polymerization in a phase state. Specific examples of methods for producing titanium trichloride compositions are proposed in JP-A-47-84478 and JP-A-51-76196.

The filler used in the present invention is one that has been added to improve the physical properties of polypropylene, and specific examples include silica, diatomaceous earth, alumina, titanium oxide, iron oxide, zinc oxide, magnesium oxide, pumice powder, Examples include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium sulfate, barium sulfate, talc, clay, mica, glass peas, carbon black, and mixtures of two or more thereof.

The size of the inorganic filler is not particularly limited, but is usually 50 microns or less, preferably 80 microns or less, and the smaller the particle size of the core granular polyolefin, the finer the filler is preferably used. The amount of filler is generally in the range of 0.1 to 150 parts by weight, preferably 10 to 150 parts by weight, based on 100 parts by weight of granular polypropylene.

The binder of the present invention has the role of firmly adhering the inorganic filler and/or foaming agent to the surface of the granular polypropylene, and for this purpose, it is necessary to melt the polypropylene in a bath melting state at a temperature at least 8°C lower than the melting point of the granular polypropylene. In view of the quality of the molded product, it is preferable to use one that has good compatibility with the granular polypropylene. Examples of binders include polyethylene, ethylene-vinyl acetate copolymers, ethylenically unsaturated carbonic acid ester copolymers (e.g. ethylene-methyl methacrylate copolymers, etc.), ethylenically unsaturated carboxylic acid metal salt copolymers (e.g. ethylene-magnesium acrylate or zinc copolymers, etc.), propylene and other olefin copolymers (propylene-ethylene copolymers, propylene-butene-1 copolymers, etc.), polyethylene or polypropylene maleic anhydride, etc. Saturated carboxylic acid modified product, ethylene-propylenecomb, ethylene-butene-1
Examples include rubber, olefin copolymers such as atactic polypropylene, petroleum resins, and polyalkylene gelylcols such as polyethylene glycol and polypropylene glycol. Special polyethylene, ethylene-vinyl acetate copolymer, ethylene-unsaturated carboxylic acid ester copolymer (e.g. ethylene-methyl methacrylate copolymer, etc.), ethylene-unsaturated carboxylic acid metal salt copolymer (e.g. ethylene-acrylic acid ester copolymer, etc.) copolymers of propylene and other olefins (propylene-ethylene copolymers, propylene-butene-1 copolymers, etc.), unsaturated carboxylic acids such as maleic anhydride of polyethylene or polypropylene Modified products, olefin copolymers such as ethylene-propylene rubber, ethylene-phthene-l rubber, and atactic polypropylene are preferred. Generally, molded products made of polypropylene to which inorganic fillers are added have higher rigidity but lower impact resistance than molded products without additives. On the other hand, it is preferable to use an olefin polymer as the binder in the granular polypropylene material for molding of the present invention because the impact strength is less reduced or the strength is improved. For example, when using granular polypropylene,
It is preferable to use polyethylene, propylene-butene-1 copolymer, ethylene-propylene rubber, ethylene-butene-1 rubber, or atactic polypropylene as the binder since impact strength is improved. These binders alone,
Either combination may be used.

The amount of binder varies depending on the type and amount of the inorganic filler and blowing agent, so it may be determined as appropriate by taking these into account, but usually the weight ratio of binder/(inorganic filler + blowing agent) is approximately 1/ l
O to about 172, preferably about 1/10 to about 174.

The blowing agent used in the present invention is a compound that is solid at room temperature and generates gases such as nitrogen, carbon dioxide, and ammonia gas when heated above the decomposition temperature. Also [at least 5°C4 below the pour point]
It is necessary to have a decomposition temperature, such as dinitronopentamethylenetetramine, azodicamide,
Known organic or inorganic blowing agents such as metal salts of zodicarbonamide, 4,4'-oxyhis (benzenesulfonyl hydrazide), toluenesulfonyl hydrazide, sorta bicarbonate, and ammonium carbonate are used. Also,
These blowing agents may be used alone or in combination of two or more, and may be used in combination with known blowing aids such as urea, urea compounds, zinc white, and zinc stearate. Good too. The amount of foaming agent used is 10 in total for resin and filler.
The amount is usually 0.1 to 1 ONM part based on the 0 weight region, but may be changed as appropriate depending on the desired expansion ratio, molding method, type of blowing agent used, and amount of gas generated. If the amount of blowing agent used is less than the lower limit, the expansion ratio will be too low, and if it is more than the upper limit, too much gas will be generated due to the decomposition of the blowing agent, which will not be able to withstand the viscosity of the resin, resulting in cracks in the foam. The gas escapes to the outside, causing contraction, and it becomes difficult to control the thickness of the foamed layer to be uniform.As a result, a smooth sheet cannot be obtained even when covered with a non-foamed layer. In terms of foaming ratio, it is 2.
From the above point, it is necessary that it be 5 times or less.

Furthermore, the materials for forming the non-foamed polypropylene layer of 500 microns or less include polypropylene homopolymer,
A copolymer consisting of propylene and one or more α-olefins other than propylene can be used.

Furthermore, in order to improve the physical properties of the granular porin material for foam molding of the present invention, we have developed a method for improving the stability and quality of conventional polypropylene.
Various additional antioxidants, light stabilizers and pigments may also be used. The amount of these compounds may be appropriately determined in consideration of adhesion, but since the amount added is generally smaller than that of the filler, the amount of the binder may be greater than the amount of the compounding agent. An example of a stabilizer is 2.6 as an antioxidant.
- ditertiarybutylpara-cresol, calcium stearate, tetra[methylene-8-(8,5 ditertiarybutyl-4-hydroxyphenyl)propionate comethane, etc.; light stabilizers such as 2-(2'-hydroxy-51- Examples include, but are not limited to, methylphenyl)benzotriazole, 2-hydroxy-4-octylbenzophenone, and the like. Examples of pigments include organic or inorganic pigments used for coloring polypropylene.

An example of the method for producing the granular polypropylene material for foam molding of the present invention will be shown below. The equipment used is a mixer with an agitator equipped with a mantle (which can heat the contents), such as Henschel mixer, Super mixer (trade name,
■Manufactured by Shuen Seisakusho), etc. In this IJZ mixer, the granular polyolefin, inorganic filler, binder, and/or foaming agent are heated to a temperature slightly higher than the melting point of the binder while mixing various compounding agents as necessary. As a result, the molten binder, including the inorganic filler, various compounding agents, and/or blowing agent, firmly and uniformly adheres to the surface of the granular polypropylene. If this is taken out as it is or after being slightly cooled, a granular polypropylene for molding with good fluidity can be obtained. When produced in this manner, the binder preferably remains molten at a temperature at least 8°C below the melting point of the particulate polypropylene and at least 5°C below the decomposition temperature of the blowing agent. This is to prevent the granular polypropylene from melting and to prevent the blowing agent from decomposing in the mixer. Further, the shape of the binder is preferably as small as possible in order to improve the dispersion of the filler and foaming agent and to melt the binder in a short time. For example, if polyethylene is used as a binder, rather than using pellets obtained by extrusion granulation as is, for example, it is better to crush the pellets and use a powder product that has passed through 30 meshes. It can be attached with.

Next, although there are no particular limitations on the multilayer sheet manufacturing apparatus, by way of example, the following apparatus can be used to obtain the desired multilayer sheet. In other words, by using a flat gouer with a merging resin passage in which flows from multiple manifolds connected to multiple extruders, resin passages, and multiple resin passage forces are merged and integrated, a foam layer is formed within the gouie. The material and the non-foamed layer material are fused together in a confluent resin passage and extruded to form a multilayer sheet.

Next, the present invention will be specifically explained with reference to the illustrated embodiments.

In Fig. 1, the foam layer material forming the inner layer sent out from the main extruder (not shown) is distributed over the entire width of the goo by an inner layer manifold 2 provided in the goo body 1, and is made into a uniform flow rate by an inner layer choke knob 18+. It is conditioned and led via a resin channel 9 formed by an inner lip 5.6 into a confluent resin channel 12 formed by a grip lip 7.8. The lightless foam layer material forming the surface layer sent out from the sub-extruder (not shown) is distributed over the entire width of the surface layer by the surface layer manifold 8.4, adjusted to a uniform flow rate by the surface layer choker 14.15, and then passed through the resin passage 10. .11 and is led to a confluent resin passage 12. The inner layer and the surface layer are fused and integrated in the confluent resin passage 12 formed by the gouly lip 7.8, and extruded from the gouly outlet. FIG. 2 shows an example of the cross section of the polypropylene multilayer sheet 1 formed by extrusion in this manner. 16. ．． 18 is a non-foamed layer made of polypropylene, and 17 is a foamed layer.

FIG. 8 shows a polypropylene multilayer sheet with a non-foamed layer formed on only one side. 19 is a non-foamed layer made of polypropylene, and 20 is a foamed layer.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited thereto.

Example 1 (1) Polymerization of propylene A stirred stainless steel autoclave with an internal volume of aoooz was purged with nitrogen, and diethylaluminum chloride 18
00y, Japanese Unexamined Patent Publication No. 58-88289 Mei? Example 15 of Iui book, catalyst WA! ! l! Titanium trichloride solid catalyst (B) obtained by the method shown in Method 8 50! was charged, and hydrogen corresponding to a partial pressure of 0,5 positive/- was added.

Then, 840 Kf of liquid propylene was pressurized into the autoclave, and the autoclave was maintained at 65°C to continue polymerization for 4 hours.

After polymerization, unreacted monomers are purged and methanol 6
01 was added to decompose the catalyst.

The produced vopropylene was separated by F using a centrifugal filter and heated to 60°C.
When the mixture was dried under reduced pressure, spherical granular propylene with a uniform particle size of 890 Kq was obtained. The melting point of this polypropylene was measured with a differential thermometer (manufactured by PerkinElmer) and found to be 165''c.

This granular polypropylene had an average particle size of about 600 microns and a bulk specific gravity of about 0.49.

(2) Production of foam molding material (A) 100t super mixer (product name ■Circle production M*)
2 Kg/cJG of steam was passed through it.

To this (1): 17.5Kf of granular polypropylene obtained by polymerization of propylene, Sumikasen@)G as a binder.
aO2 (low-density polyethylene melting point 110°C, Sumima Kagaku Kogyo ■! &Ri's 30-mesh passing powder 0.5 Kg, as a foaming agent Cellmic CAP (decomposition temperature 125°C, manufactured by Sankyo Kasei ■) 0.4 Kq, inorganic filling 2.0 kg of talc with an average particle size of 8 microns as an agent and tert-butyl p-cresol/tetra[methylene-3-(
3,5-diterbutyl-4-hydroxyphenyl)propionate comethane-2/1 (M star ratio) 180
y and stirred at 675 rPln. Twelve minutes after the start of stirring, the temperature reached 115°C, and when the contents were discharged, a spherical and smooth molding material was obtained. The foaming agent, talc, and stabilizer adhered uniformly and firmly to the granular polypropylene, and no peeling of the foaming agent, talc, and stabilizer was observed even when the polypropylene was placed in the palm of the hand and rubbed strongly with the fingertips.

Almost no adhesion was observed on the inner wall of the super mixer.

(3) Molding of multilayer sheet The above-mentioned foam molding material (A) was used as the foam layer material, and polypropylene (Sumitomo Noblen FL6411MI=7, manufactured by Sumitomo Chemical Co., Ltd.) was used as the non-foam layer material. Using the equipment shown, in each case the extruder temperature was 220
A multilayer sheet having the structure shown in Table 1 was obtained at a molding temperature of 200° C. and a soybean temperature of 200° C.

The multilayer sheet of the present invention is a sheet having a foam layer exhibiting a foaming ratio of 8.0 times, or a polypropylene pellet containing a filler (a 1=1 blend product of Noblen BWH52/W501) with the same amount of foaming agent (Celmic CAD). Compared to a sheet using a tri-blend (foam molding material B), the surface coated with the non-foamed layer was smooth and had sufficient commercial value.

Table 1

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a die used to extrude the multilayer sheet of the present invention. FIG. 2 is a cross-sectional view of a multilayer sheet obtained using the die of FIG. FIG. 3 is a cross-sectional view of another example of the multilayer sheet of the present invention. In the figure, 1 is the die body, 2 is the inner layer manifold, and 3 is the die body.
, 4 are surface layer manifolds, 5 and 6 are inner layer lips, 7 and 8
is the die lip, 9, 10, 11゜12 is the resin passage, 1
3 is the inner layer chalk bar, 14.15 is the surface layer chalk bar 16.18.19 is the polypropylene non-foamed layer, 17.
20 each indicates a foam layer.

Claims (1)

[Scope of Claims] (1) Bulk specific gravity is 0.45 or more, average particle size 150-200
Granular polypropylene for molding having at least one layer consisting of a filler and a binder on the surface of 0 micron granular polypropylene and a foaming agent, or a bulk specific gravity of 0.45 or more,
A multilayer sheet made of granular polypropylene for foam molding, which has at least one layer consisting of a filler, a binder, and a foaming agent on the surface of granular polypropylene having an average particle size of 150 to 2,000. (2) The binder is an olefinic polymer that is in a molten state at a temperature at least 8"C below the melting point of the granular polypropylene, and the blowing agent has a decomposition temperature at least 5"C higher than the melting point or pour point of the binder. (8) The polypropylene multilayer sheet according to claim 1, which has a foam layer having an expansion ratio of 2.5 times or less. (4) A polypropylene multilayer sheet according to claim 1, wherein both or one side of the foam layer is coated with a non-foamed polypropylene layer having a thickness of 500 ton or more.