JPS62189144A - Foam of closslinking polyolefin resin having continuous bubble and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain the polyolefin resin form of a continuous bubbles having compression charactristic and rigidity which are equal to or higher than these properties of the foam having independent bubble by a method wherein mechanical deforming operation is applied on the closslinking foam having an independent bubble structure having the percentage of gel content within a specified range to convert the foam into the closslinking foam having a continuous bubble structure. CONSTITUTION:A molding sheet, obtained from polyolefin resin, is closslinked and foamed to obtain closslinking resin foam in which the percentage of gel content (Gs) of the surface layer thereof is equal to or larger than the percentage of gel content (Gm) of the central portion thereof and the percentages (Gs) and (Gm) are within the range of 10%-60% while the average diameter of the bubbles is within the range of 0.3-1.0mm; then, mechanical deforming operation is applied on the closslinking polyolefin series resin foam to make the bubbles in the foam continuous. This closslinking polyolefin resin foam, having the continuous bubbles, has the continuous bubble rate (T) of 30% or more, a compression index (P) of 0.1-10 and the toughness index (N) of 100-2,500.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a crosslinked polyolefin resin foam having an open cell structure and excellent mechanical properties such as compression properties and toughness, and a method for producing the same.

(Prior art) Conventionally, a method for manufacturing a polyolefin resin foam having an open cell structure is disclosed in Japanese Patent Publication No. 47-31695, Equity nH4.
9-10350, JP-A-54-63172, and JP-A-56-121739.

However, the foams with open cells obtained by these known methods are simply made of open cells, and are poor in compression properties and toughness compared to foams with closed cells. There was a problem with its lack of practicality.

(Problems that the invention attempts to solve) Objectives of the invention (3J1, continuous air bubbles (8 structures), shrinkage properties, t'f, a3 and strong 'l]l'
This invention provides a polyolefin-based resin foam that has closed cells and open cells that have physical properties equivalent to or better than those of resin foam, and a method for producing the same. .

(Means for Solving the Problems 1) - An object of the present invention is to provide a foam in which the gel fraction (Gs) in the surface layer is the same as or equal to the gel fraction (Gm) in the center, and the gel fraction (Gs) of the surface layer and the gel fraction (a m ) of the center
or within the range of 10% to 60%, the open cell ratio (D) is 30% or more, the compression index (') is 0.1 to 10, and the toughness index (N) is within the range of 100 to 2500. A frame (n polyolefin resin foam J:
The gel fraction (Gs) in the surface layer is the same as or equal to the gel fraction (G m ) in the center, and the gel fraction in the surface layer is the same as the gel fraction (G m ) in the center. minute 1', (OS) it-; J, and central gel fraction? '-(G m ) or 10%''-□ Within the 11 old Ill of 60%, the average bubble diameter is (1,3~1, (
') Cross-linked polyolenoin system (1
The manufacturing of cross-linked polyolefin resin foams with open cells characterized by mechanically shaping the resin foam to make the cells in the foam open cells) J. can be achieved.

When referring to the polyolefin resin (or composition, hereinafter referred to as F-) resin that constitutes and covers the foam of the present invention, CL Illll
Metallic materials are not particularly limited, such as low-density polyethylene, linear low-density polyethylene, high-density anti-polyJ-brane, poly-V [1-pyrene, These resins include -I dylene-vinyl acetate copolymer, ethylene-acrylic acid alkyl ester copolymer, etc. 11 Germany and IJ, 2
It may be a mixture of more than one type, or it may be a resin composition in which other resins such as polyvinyl chloride, polyvinyl chloride graph 1 and covalent coalescence are blended.

The characteristics of the present invention are, first, that the cell structure of the crosslinked polyolefin resin foam is not closed cells but open cells;
and the gel fraction (Gs) in the surface layer of the foam is the same as the gel fraction (Gm) in the center, or the gel fraction (Gs) in the surface layer and the gel fraction in the center are The ratio (Gm) is within the range of 10% to 60%.

That is, when the crosslinked foam has open cells, it is necessary that the gel fraction (Qs and Gm) of the surface layer part and the center part satisfy the above numerical range, and this J:
Only by satisfying these requirements can the compressive index (P) of 0.1 to 10 and the toughness index (
This makes it possible to satisfy the condition ↑ No. 1 that N) is within the range of 100 to 2,500.

More specifically, the gel fraction GS of the surface layer of the foam is
If it is smaller than the gel fraction Qm in the center, it is difficult to make the cell structure continuous, which is undesirable because the compression index, toughness index, and productivity of the foam will decrease.

In addition, if the gel fraction (Gs) in the surface layer and the gel fraction (G m ) in the center are smaller than 10%, the compression properties will be poor, so 60% is preferable.
Exceeding this is not desirable, as it reduces strength and strength.

The open cell rate of the crosslinked foam of the present invention (30%
It is necessary that the open cell rate is 30%J or more.
: When the diameter becomes smaller, the insulation properties as a foam (heat retention/1
4>, elasticity, buffering 1 (in 1, etc., the practical performance requirement ↑) is often not satisfied, which is undesirable.

In addition, if the compression index (P) specified in the present invention is less than 0°1, the foam will deform (in contrast, it will easily follow the vortices, and the cushioning properties will be significantly reduced, so it is not preferable, and if it exceeds 10, it will be continuous). Although it is foamed, it becomes a foam with high deformation stress, which is undesirable because the cushioning property decreases.Also, the toughness index (N
) is less than 100, it is not suitable for use as a foam ↑ (Practical performance 14 - 1-1 〇 - Undesirable, as cracks may occur due to deformation of 1 when bent low), and if T1m exceeds 2500, post-additions such as molding etc. This is preferable because it will worsen the condition.

The structure of the present invention that covers the characteristics of J: is formed by molding one resin into a sheet and then crosslinking and foaming. However, after crosslinking and foaming, the gel fraction (Gs) in the surface layer of the foam is set to be the same as or larger than the gel fraction (a m ) in the center of the foam, and the gel fraction (Gs) in the surface layer is Gs) J-3J: A crosslinked polyolefin foam with a gel fraction (Gm) in the center of the foam in the range of 10% to 60% and an average cell diameter of 0.3 to 1.Qmm; By applying mechanical deformation to a crosslinked foam having the following J=unaglu fraction and H(i uniformity) (diameter) to make the cells in the foam open, ) b.

In other words, the gel fraction (Gm) in the surface layer is higher than the gel fraction (Gm) in the center of the polyolefin resin molded sheet.
s) If Ca is small, then after foaming and crosslinking the molded sheet ~1, mechanical deformation is applied to make the cells of the foam open, the mechanical deformation m is increased. If the number of deformations is not increased or the number of deformations is not increased, the foam covering the open cell structure, which will affect the open cell ratio a3J and the physical properties of the foam, which are the objectives of the present invention, will not be produced. This is preferable because the decrease in '[)1 becomes large.

If it is replaced, 47r i'/iIJ according to the manufacturing method of the present invention
,,Germany A''/Cubic Soup having a gel fraction within the above-mentioned range was placed on the right side (by applying a mechanical deformation operation to the foam,
The point is to convert the foam into a crosslinked foam having an open cell characteristic with a gel fraction within the same range.

Specifically, by myself! Compared to the gel fraction (G m ) in the center of the crosslinked foam with a cell structure, the gel fraction (Gs
) is small, mechanical deformation (when converting the cell structure of the foam into open cells) is increased, and the number of deformations is increased. If so, it is not possible to convert the [1 and 16 open cell foams] of the present invention into a suitable foam, and 'I? This is preferable because the r dimension is reduced by 1.

In addition, the above gel fraction C3d'5 cJ, and G rl'l
(1':') When each ratio is lower than 10, no matter how mechanically deformed, the cell will become open or closed, and if it exceeds 60%, even if it becomes open cell. It is difficult to obtain a cross-linked foam with low toughness and an open cell structure that is specific to the present invention.

The average cell diameter of the crosslinked foam forming the closed cell structure is 0.3 to 1. Qmm, preferably 0, II ~ 0
．． If the cell diameter is outside the range of 8 mm, for example, if the average cell diameter is smaller than 0.1 mm, the open cell ratio is 30, regardless of the mechanical deformation operation that converts closed cells into open cells.
It becomes difficult to convert into a cross-linked foam having a cell density exceeding 1.5% (open cell ratio), and a good foam with +4t when compressed cannot be obtained. If it is larger than Omm, it is easy to make open cells by the above-mentioned mechanical deformation operation, but the thickness of the cell membrane of the open-celled foam becomes thinner, leading to a decrease in the toughness of the foam. undesirable for this reason.

The open cell ratio specified in the present invention is 30% or more, the squeezing index is (one) or 0.1 to 10, and the toughness index (N) is 100 to 2.
As an example of the mechanical deformation stage 1 and the row row 1 for converting the open cell (1♂1) 15 in the range of 2 (using an in-line compression []-le gap, and adjusting the 1.1' l-le spacing within the range of 0.5 to 30% of the thickness of the foam, ]-]
By controlling the rotation ratio within the range of 1:0.5 to 1:2.0 and the speed of the ☆ shape from 0.3 ffl/min to within the range of -100 m/min, the above object It is possible to produce a foam that has an open cell structure covering it.

t-z In a-3 of the production method of the present invention, the polyolefin resin sheet before foaming may contain azodicarbonamide, dinitrosopentamethylenetetramine, etc., in addition to the polyolefin resin described above, and as necessary. A cross-linking agent that generates radicals upon heating is mixed therein, and the foaming agent and the cross-linking agent are kept in a wet M in which they do not decompose, and then molded, for example, into a sheet shape. Then, by applying a method such as ionization/l'l radiation crosslinking method or chemical crosslinking method to this molded 1J sheet 1 disk-shaped product, the above-mentioned gel fraction range of the front body part and center part is satisfied. In the case of ionizable cross-linking, the sheet size is determined by controlling the size of the cut-off wire energy or the penetration depth of radiation, and in the case of chemical cross-linking, the cross-linking speed or heat is controlled by heating. A crosslinked foam within the above-mentioned gel fraction range specified in the present invention can be obtained by adopting the method 11 in which crosslinking and foaming are carried out simultaneously during foaming or foaming is slightly prioritized.

For the ionizing crosslinking method, α is used as a high energy beam.
, β, γ, X-rays, electron beams, middle and 1/1 rays, etc., are usually
Using a high-energy key electron beam irradiator, e.g.
Crosslinking is carried out by applying an electron beam at a dose of Mrad to the sheet. In this case, 0.1 to 10 parts by weight of various known crosslinking aids, such as divinylbenzene, diallylphthale, 1 to 10 parts by weight, are added to the polyolefin resin of the present invention. Electron beam crosslinking may be carried out by adding heliacrylate or the like. Instead of this H-ray irradiation, it is also possible to add an ultraviolet sensitizer such as benzophenone and crosslink by irradiating ultraviolet rays. Also,
In the case of the chemical crosslinking method, dicumyl bar Δ4 reit, ditercharivedelper A kylid < r on the right side, peroxide is mixed with O11 to 5 double suspensions, heat-reduced (degrees and temperature controlled to react, and cross-linked). Furthermore, a silane cross-linking method in which these cross-linking agents and a vinyl silane such as vinyltrimethoxysilane are kneaded to form a graft, or a silane cross-linking method in which cross-linking is performed by a siloxylene condensation reaction, etc., may be carried out as appropriate. can be applied.

The polyolefin resin molded sheet thus obtained is
Continuously formed sheet and L) in hot air atmosphere or salt bath
- to rapidly decompose the foaming agent contained within the molded sheet, thereby converting it into a foam having a closed cell structure.

In addition, within a range that does not impair the purpose of the present invention, the polyolefin resin used for producing the foam of the present invention may include, within a range that does not affect the compression index, toughness index, etc.
Inorganic fillers, lubricants, antioxidants, ultraviolet absorbers, colorants, antistatic agents, flame retardants, and other inorganic substances that impart ↑I function (=I), preferably with a particle size of 0.5 to 60
MIKU
) can be blended.

The crosslinked, expanded closed cell foam is then deformed by the mechanical deformation operation described above, preferably by introducing a mechanical deformation device into the foam line; Production: By converting the closed cells inside the foam into open cells, it is possible to produce a crosslinked polyolefin resin foam having an open cell structure of 4γ according to the present invention.

The obtained crosslinked polyolefin resin foam of the present invention having an open cell structure has at least one surface containing]
Adhesives can be applied through Ronaden treatment, coating, etc., and lamination processing can be performed to improve workability.1. Plastic films, sheets 1~, other foam sheets and metal foils are laminated together, and composite horizontal markings are applied using extrusion lamination, etc., that is, various types of 710
1 technique can be applied.

(Effects of the Invention) The crosslinked polyolefin resin foam having an open cell structure according to the present invention thus obtained has excellent compression t/l and toughness IJ1 due to its open cell structure. It is used in many applications such as thermal insulation materials for clothing, underlays for Carpella 1, automobile interior materials, sports mats, clothing tapes, various cushioning base materials, and thermal insulation materials.
It can be expanded.

The effects of the present invention will be explained in more detail below based on Examples.

In the present invention, the gel fractions GS and Gm, the open cell ratio (T), the compression index (P), and the toughness index (N>) are values measured by the following method.

(1> Gel fraction (Gs and Gm): Cut the sample cut out from the foam into small pieces, weigh approximately 0.2Cl accurately, and collect.The accurately weighed sample is placed in tetralin at 135°C for 30 minutes. After soaking for a period of time, the uncrosslinked portion was eluted, the insoluble portion was taken out, washed with ethanol, air-dried and vacuum-dried to remove the volatile portion, and then carefully weighed with W.
), calculate the gel fraction using the following formula.

Gel fraction (%) - (Wlo, 2) X 100 Here, the gel fraction (GS) of the surface layer is the surface layer 0 of the foam.
．． This is the lean pull value taken by slicing a 3mm deep part, and the gel fraction (Gm) in the center is the value of a sample taken by slicing a 3mm part of the central reservoir Q of the foam. .

(2) Open cell ratio (di) This is a value measured according to the measurement method specified in ASTM-D-2856.

(3> Compression index (P) The value is expressed by the following formula.

P-(25% compression hardness) is J Is-
This is a value measured in accordance with the measurement method specified in Japan-6401.

(4) Toughness index (N) It is a value defined by the following formula.

N- (Breaking strength> × (Breaking elongation) Here, the breaking strength and breaking elongation are JIS-6767
This is a value measured according to the measurement method specified in A.

It was shown.

Examples 1 to 5, Comparative Examples 1 to 4 The polyolefin resin compositions shown in Table 1 were introduced into an extruder and molded into sheets.

These molded sheets 1 to 5 were heated to 1 to 5 Q Mrad using an electron beam irradiation device (R-2 manufactured by Fl Shin High Voltage Co., Ltd.).
irradiated with a dose of 1Ff cross-linked seams 1~
Foaming was effected by heating 220-240' CL near 11 on a bath.

Roll B with a diameter of 5 inches, which can change the roll spacing, circumferential speed ratio, and speed
The foam sheet 1 is compressed using a device equipped with Y.
The bubbles of ~ were made into open cells.

Table 1 shows the capacity of the open-cell foam sheets 1 to 1.

From the table, GS and J of Examples 1 to 5 are as follows:
Comparative Examples 1 to 40 had good open cell ratio, compression index, and toughness index over a wide composition range because the compression interval and circumferential speed ratio were within appropriate ranges. Foam Sea 1 - IJl, composition (,li, similar to Examples 1 to 5, but the, GS and Gm, compression interval, peripheral speed ratio are not appropriate, open cell ratio, compression index, It can be seen that the foam sheet is insufficient in toughness index.

Claims (2)

[Claims] (1) The gel fraction (Gs) in the surface layer of the foam is the same as or larger than the gel fraction (Gm) in the center, and the gel fraction (Gs) in the surface layer and the gel in the center Fraction (Gm)
is within the range of 10% to 60%, the open cell ratio (T) is 30% or more, the compression index (P) is within the range of 0.1 to 10, and the toughness index (N) is within the range of 100 to 2500. Crosslinked polyolefin resin foam with open cells. (2) A molded sheet obtained from a polyolefin resin is crosslinked and foamed so that the gel fraction (Gs) in the surface layer is the same or larger than the gel fraction (Gm) in the center, and Gel fraction (Gs) and central gel fraction (Gm
) is within the range of 10% to 60%, and the average bubble diameter is 0.3 to 60%.
A crosslinked polyolefin resin foam having open cells, characterized in that the foam is made into a crosslinked polyolefin resin foam having a diameter within the range of 1.0 mm, and then mechanically deformed to convert the closed cells in the foam into open cells. Manufacturing method.