JP2003313341A - Foamed olefin resin sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foamed olefin resin sheet being one prepared by foaming a sheet obtained by calendering, having a homogeneous cellular state, having bending processability as well as suitable hardness, and being subject to fabrication such as high-frequency welding and foil stamping. <P>SOLUTION: The foamed sheet is one obtained by compounding a base resin prepared by blending an ethylene/vinyl acetate copolymer resin with an ethylene/ methyl methacrylate copolymer resin with a blowing agent and a filler, wherein the weight ratio between the following components of the resin component is represented by formula (1), and the weight ratio of the total of the following components to the resin component is represented by formula (2): vinyl acetate component/methyl methacrylate component = 0.25-4.5...(1), and (vinyl acetate component + methyl methacrylate component)/resin component = 0.13-0.27...(2). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an olefin having a small impact resilience, which is suitable for stationery, various cases, packaging, bags, furniture, interior materials, etc., and particularly suitable for binding such as the cover of a notebook. A resin-based foam sheet.

[0002]

2. Description of the Related Art Conventionally, as a foamed sheet used for the above-mentioned purpose, a foamed sheet composed of a vinyl chloride resin and a foaming agent has been widely used. Foamed sheets using vinyl chloride resin have good foamability, good adjustment of hardness depending on the amount of plasticizer added, and good mass productivity by calender molding.Furthermore, bending workability, high-frequency welding, foil stamping, etc. The secondary workability is also good, but on the other hand, there are problems of stickiness and stains due to bleeding of the plasticizer, and generation of hydrogen chloride gas during waste combustion.

As a solution to these problems, there is a foamed sheet using a foaming agent in polyethylene, ethylene-propylene copolymer resin, ethylene-propylene-butene copolymer resin, etc. However, due to lack of flexibility, impact resilience is provided. Is too large to be used for bending and is not suitable for high-frequency welding, which limits its application (many olefin-based foam sheets are used by welding to other synthetic resin sheets. Is required).
Suitable resins for high-frequency welding include ethylene-vinyl acetate copolymer resin, ethylene-methyl methacrylate copolymer resin, etc., but these resin blends strongly adhere to a calender roll during calender molding of a sheet, or Even if a sheet is obtained, the foamed sheet obtained by heat-foaming the sheet has problems that it is difficult to obtain a uniform cell state, the surface state becomes uneven, and the foil stamping workability deteriorates.

[0004]

DISCLOSURE OF THE INVENTION As a result of intensive studies in view of the above problems, the present invention is surprisingly mainly composed of a mixture of an ethylene-vinyl acetate copolymer resin and an ethylene-methyl methacrylate copolymer resin. Experimental data showing that a mixture of a resin and a filler and a foaming agent has excellent calender moldability, and the foamed sheet obtained by foaming the obtained sheet by heating has excellent secondary processability. The present invention has been achieved. That is, the invention of the present application is a foamed sheet obtained by foaming a sheet obtained by calender molding, which has a uniform cell structure, has a moderate hardness, and has bending workability, and has two features such as high-frequency welding processing and foil stamping processing. It is an object of the present invention to provide an olefin resin foam sheet having good subsequent processability.

[0005]

The olefin resin foamed sheet of the present invention comprises a main resin formed by mixing an ethylene-vinyl acetate copolymer resin and an ethylene-methyl methacrylate copolymer resin, a foaming agent and a filler. Which is a foamed sheet obtained by blending the following, wherein the weight ratio of the following components in the resin component is represented by the formula (1) and the total weight ratio of the following components to the resin component is represented by the formula (2). Is characterized by. Vinyl acetate component / methyl methacrylate component = 0.25 to 4.5 (1) (Vinyl acetate component + methyl methacrylate component) / resin content = 0.13 to 0.27 ... (2) In addition, the resin component includes a resin other than the main resin when used in combination. The value of equation (1) is
If it is less than 0.25, the calender moldability and bending processability tend to deteriorate, and if it exceeds 4.5, the calender moldability tends to be poor. If the value of the expression (2) is less than 0.13, the high frequency welding workability is poor, and if it exceeds 0.27, the calender moldability is poor.

When the olefin resin foam sheet of the present invention is used as a binding sheet such as the cover of a notebook,
It is preferable that the range represented by the formula (1) is 1.5 to 4.5 and the range represented by the formula (2) is 0.15 to 0.27. If the value of (1) is less than 1.5, the workability in bending the cover sheet tends to deteriorate. If the value of the formula (2) is less than 0.15, the welding of the end portion tends to be insufficient.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The ethylene-vinyl acetate copolymer resin used in the present invention has a vinyl acetate component of 10 to 30.
Weight% is preferred. If it is less than 10% by weight, the high frequency welding property of the foamed sheet will be deteriorated, and if it exceeds 30% by weight, the heat deformability and the calender moldability will tend to be deteriorated. As the ethylene-vinyl acetate copolymer resin, those having different contents of vinyl acetate component may be used, and as long as the properties of the foamed sheet are not impaired, monomer components other than ethylene and vinyl acetate are used. It may be a copolymerized product of.

As the ethylene-methyl methacrylate copolymer resin, the methyl methacrylate component is 10 to 30% by weight.
Are preferred. If it is less than 10% by weight, the high frequency welding property of the foamed sheet will be deteriorated, and if it exceeds 30% by weight, the heat deformability and the calender moldability will tend to be deteriorated. The foamed sheet may be copolymerized with a monomer component other than ethylene and methyl methacrylate as long as the characteristics of the foamed sheet are not impaired.

In the present invention, an ethylene-vinyl acetate copolymer resin and an ethylene-methyl methacrylate copolymer resin are main resins, but other materials such as polyethylene can be used as long as the characteristics of the foamed sheet are not impaired. The resin can be used together.

The resin used in the present invention contains a foaming agent for foaming the sheet. As the foaming agent, a thermal decomposition type chemical foaming agent is preferable, for example, azodicarbonamide, paratoluenesulfonyl hydrazide, 4,
4'oxybisbenzenesulfonyl hydrazide, azobisisobutyronitrile, dinitropentamethylenetetramine and the like can be mentioned. A particularly suitable blowing agent is azodicarbonamide. The foamed sheet of the present invention has a foaming ratio of about 1.5 to 3.5, and a specific gravity of 0.
It is 3 to 0.7. If the expansion ratio is too high, the surface condition deteriorates, and if it is low, the flexibility is insufficient.

Further, a filler is blended with the above resin in order to facilitate the kneading operation of the resin blend and to reduce the manufacturing cost. As the filler, calcium carbonate, clay,
Talc and the like are preferable, and other examples include silica, zeolite, inorganic fillers such as calcium metasilicate, and organic fillers. The particle size is 20 μm or less, preferably 0.
It is preferably 5 to 3 μm. When the particle size exceeds 20 μm, the surface condition of the foamed sheet tends to deteriorate. Further, if the particle size is less than 0.5 μm, it tends to be difficult to uniformly mix. The blending amount is about 1 to 40 parts by weight with respect to 100 parts by weight of the resin. If it is less than 1 part by weight, the effect is not sufficient, and if it exceeds 40 parts by weight, the foamed sheet becomes hard, and the foamability at the stage of molding the foamed sheet is deteriorated and the cell structure is deteriorated.

Further, if necessary, the above resin may include a light stabilizer such as an antistatic agent, an antioxidant and a hindered compound,
You may mix | blend various additives, such as a lubricant, an ultraviolet absorber, and coloring agents, such as a pigment.

The above-mentioned resin, foaming agent, filler, and additive are kneaded by a known means to form a resin mixture. The resin composition can be formed into a sheet by a roll heated to such an extent that the foaming agent does not foam, and the sheet can be foamed by heating the sheet to a thermal decomposition temperature or higher to obtain the foamed sheet of the present invention. In addition, embossing may be performed using an embossing roll or the like. The embossing may be performed either before or after foaming, but it is usually preferable to perform embossing after foaming.

The foamed sheet of the present invention can be improved in properties such as blocking and tensile strength by laminating a base cloth layer on the back side. As the base cloth layer, vinyl leather, woven cloth usually used for synthetic leather, knitted cloth, cloth such as non-woven cloth are suitable, and examples thereof include woven cloth and knitted cloth such as cotton, rayon, polyester, polyamide, polyethylene, Examples include various non-woven fabrics made of synthetic fibers such as polypropylene and polyester. It is preferable to use a mesh-like base fabric layer in consideration of performing high frequency welding.
Conveniently, the base fabric layer is laminated immediately after the sheet is formed by calendering. Of course, it can be performed after foaming the sheet. During this stacking,
It is preferable to subject the base fabric layer side to an adhesive reinforcement treatment such as a primer.

Further, the foamed sheet of the present invention may have a non-foamed surface layer laminated on the surface side. As the surface layer, it is preferable to use the same composition as that of the foamed sheet with the foaming agent removed, from the viewpoint of adhesion. By providing the surface layer or the surface-treated layer in this manner, abrasion resistance, oleic acid resistance and the like can be improved. The thickness of the surface layer is 0.
1 to 0.2 mm is preferable. If it is thinner than this, there is a problem that it is difficult to obtain a uniform thickness, and if it is thicker than this, there is a problem that the repulsive force of the sheet becomes strong and it becomes unsuitable for bending. The surface layer may be laminated either before or after foaming the sheet, but it is convenient in terms of process to laminate before the foaming.

Further, a surface treatment layer such as silicone or a fluorine-containing treatment agent can be provided by gravure coating, spraying or the like regardless of whether or not the surface layer is provided for the purpose of improving abrasion resistance and oleic acid resistance. .

When the foamed sheet of the present invention is used for binding a cover such as a notebook, the finished thickness is 0.7 to 0.12.
The specific gravity is preferably 0.50 to 0.65 in mm. By doing so, it has an appropriate hardness (texture) and a good bending workability.

[0018]

EXAMPLES For each resin formulation shown in Tables 1 to 3,
Further, a mixture of the following additives was kneaded with a mixer to obtain a resin mixture for producing a foamed sheet used in this example and comparative examples. (Additive) The additive was added in an amount based on 100 parts by weight of the resin content. Asahi Denka Kogyo's OF-100 (2 parts by weight), Asahi Denka Kogyo's mark AP-582 (0.65 parts by weight), Asahi Denka Kogyo's ADEKA STAB AX-38 (0.
4 parts by weight), ADEKA STAB AO-50 manufactured by Asahi Denka Co., Ltd.
(0.15 parts by weight), ADEKA STAB AX manufactured by Asahi Denka Co., Ltd.
-71 (0.07 parts by weight) The resin composition for producing a foamed sheet prepared as described above was mixed with 1 so that the weight of the foamed sheet would be 400 g / m ^2.
The sheet was made into a sheet by a 35 ° C. calender roll, and the obtained sheet was heated at 200 ° C. for 2 minutes to obtain each foamed sheet. The evaluation of the obtained foamed sheets is shown in Tables 1 to 3.

(Evaluation method) Calendar formability ○ = good, △ = acceptable, × = calender molding not possible.

Foamability of sheet ○ = good, △ = acceptable

Hardness (Bending): According to JIS L 1096, a bending test 45 ° canterever method. ○ = 65 or more and less than 75 (good as a foamed sheet), ◎ =
75 or more and less than 90 (very good texture for binding), ◯ = 90 or more and less than 110 (good as a foam sheet), Δ = 110 to less than 130 (possible as a foam sheet), x = 130 or more (cushioning property) Is poor and the texture is inferior)

Cell structure: Evaluation is based on whether the cells are homogeneous or not. ◎ = very good, ○ = good, △ = good, × = bad

Foil stamping processability: ◎ = Foil adheres clearly with a normal amount of heat, ○ = Amount of heat increases, Δ = Amount of heat increases, but adheres with a large amount of heat, but marks are formed around it × = The foil will fall off just by rubbing it with your finger

High-frequency processability: evaluated by the adhesiveness with an EVA-based polyolefin sheet. ◎ = 20 N / 2 cm width or more, ◯ = 15 N / 2 cm width or more, Δ = 5 N / 2 cm width or more, × = 5 N / 2 cm width or less

Fusing property: The state when one of the foamed sheets is melted is evaluated by comparing it with a vinyl chloride foamed sheet having substantially the same physical properties. ◎ = Easier to melt than PVC sheet, ○ = Equivalent to PVC sheet, △ = Slightly inferior to PVC sheet, X = Well inferior to PVC sheet (many burrs occur)

Bending workability: A 10 × 10 cm foamed sheet was folded in two and sandwiched between two 10 × 10 cm plates, and a load of 50 kg was released for 2 seconds. = Very good, ○ = good, △ = acceptable,

Overall evaluation: ◎ = Good for binding, ◯ = Good as foamed sheet, Δ = Available as foamed sheet, × = Not acceptable as foamed sheet. ◎ in the comprehensive evaluation is ◎ for hardness and bending workability. The other evaluation items were evaluated as ○ or higher.

[0028]

[Table 1]

* 1: Ethylene-vinyl acetate copolymer resin (Ultrasene 634 manufactured by Tosoh Corporation) * 2: Same as above (Evaflex P-19 manufactured by DuPont Mitsui)
50) * 3: Same as above (Takaroku TPO manufactured by Takaroku Co., Ltd.) = (Sumitomo TPE4552 manufactured by Sumitomo Chemical Co., Ltd./Ultrasen 6 manufactured by Tosoh Corporation)
34 / NN # 500 = 40/50/10) * 4: Ethylene-methyl methacrylate copolymer resin (Sumitomo Chemical Co., Ltd. Akulift WM403) * 5: Same as above (Sumitomo Chemical Co., Ltd. Akulift WK307) * 6: Same as ( Sumitomo Chemical Co., Ltd. Akulift WD301) * 7: Same as above (Sumitomo Chemical Co., Ltd. Akulift WD203-
1) * 8: Polyethylene (Evolution SP-0 manufactured by Mitsui Chemicals, Inc.)
540) * 9: Calcium carbonate (NN # 50 manufactured by Nitto Koka Kogyo Co., Ltd.
0) Average particle size = 4.4 μm

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

As described above, the olefin resin foamed sheet of the present invention is a main resin obtained by mixing an ethylene-vinyl acetate copolymer resin and an ethylene-methyl methacrylate copolymer resin. By using a plurality of resins containing a methyl methacrylate component in a specific ratio and a vinyl acetate component and a methyl methacrylate component in a specific amount, by compounding a foaming agent and a filler with the above resin, calender molding can be performed. A foamed sheet that can be molded can be provided, and the foamed sheet has excellent secondary workability such as foil stamping workability and high-frequency welding property.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F074 AA22 AA23 AA98 AC26 AE06                       AG01 BA13 CA29 CC04X                       CC04Y CC22X DA16 DA23                       DA33 DA37 DA52                 4J002 BB06W BB07X DE236 DJ006                       DJ016 DJ036 DJ046 EQ017                       EQ027 ES007 ET007 FA086                       FD016 FD327 GC00 GG00

Claims (2)

[Claims] 1. A foamed sheet obtained by mixing a foaming agent and a filler into a main resin obtained by mixing an ethylene-vinyl acetate copolymer resin and an ethylene-methyl methacrylate copolymer resin. An olefin-based resin foam sheet, wherein the weight ratio of the following components in the formula is (1), and the total weight ratio of the following components to the resin content is represented by the formula (2). (1) Vinyl acetate component / methyl methacrylate component = 0.
25-4.5 (2) (vinyl acetate component + methyl methacrylate component) /
Resin content = 0.13 to 0.27 2. The JIS has a thickness of 0.7 to 1.2 mm.
The olefin resin foam sheet according to claim 1, wherein the flexibility according to the 45 ° canterever method defined in L1096 is 75 mm or more and less than 90 mm.