JPH06313053A - Elastic tape and its production - Google Patents

Abstract

PURPOSE:To obtain the subject tape useful for a ribbon of simple mask and diaper gathers comprising a thermoplastic resin, an ethylene-propylene-diene copolymer and a low-density ethylenic resin in a specific ratio. CONSTITUTION:This elastic tape comprises (A) 60-80wt.% of a thermoplastic resin having 170-190 deg.C softening temperature, 70-88 degree Shore A hardness, (B) 10-30wt.% of an ethylene-propylene-diene copolymer and (C) 10-30wt.% of a low-density ethylenic resin, is obtained by preferably stretching a formed film at <=60 deg.C at >=1.2 draw ratio and subjecting the film to at least >=30% stress relaxation at <= the same temperature and has <10% strain at 100% extension.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretchable tape and a method for producing the same, and more particularly to a stretchable tape that can be used as a simple mask string, diaper gather, natural rubber string substitute, and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Simple mask straps, diaper gathers,
In applications such as natural rubber string substitutes, it has excellent elasticity, small residual strain of expansion, good texture, moderate strength, ultrasonic welding with polypropylene (PP) nonwoven fabric, light and discoloration. It is difficult to do and it is required to be inexpensive. Conventionally, in applications such as a string for a simple mask as described above, there is one made of polyurethane foam, but this one has a good texture but is weak in strength. Although urethane tape is on the market, it has a good texture, but is expensive, so it is used only for some mask strings. Further, although the urethane film is used for the application, there is a problem that the strain at 100% elongation is 10% or more and the strength at low stress of 100% or less is too strong, and the texture is also poor. Is.

[0003]

In view of such prior art, the present invention has excellent stretchability, small stretch residual strain, good texture, moderate strength and polypropylene ( It is an object of the present invention to provide an elastic tape that can be ultrasonically welded to a non-woven fabric made of PP), is light, does not easily discolor, and is inexpensive, and a method for producing the same.

[0004]

The present invention comprises (a) 60-80% by weight of a thermoplastic polyurethane resin having a softening temperature of 170-190 ° C. and a Shore A hardness of 70-88 degrees.
(B) Ethylene-propylene-diene copolymer 10 to 3
0% by weight and (c) low density polyethylene resin 10 to 3
An elastic tape comprising a composition containing 0% by weight and having a strain at 100% elongation of less than 10%, and a temperature of 60 ° C. or less after molding the composition into a film. The gist is a method for producing an elastic tape, which comprises uniaxially stretching 1.2 times or more and performing stress relaxation of at least 30% or more at the same temperature or less.

The present invention will be described in detail below. Examples of the (a) thermoplastic polyurethane resin in the present invention include:
Polyurethane elastomers such as polyester type, adipate type, polyether type, polycaprolactone type and the like can be mentioned. Of these, polyester-based polyurethane elastomers are preferred for the purposes desired by the present invention. Such a thermoplastic polyurethane elastomer has a softening temperature of 1
It is required to have a Shore A hardness (JIS A hardness) of 70 to 88 at 70 to 190 ° C. Softening temperature is 17
When the temperature is lower than 0 ° C., the inflation tube is easily blocked during film formation, and it becomes difficult to peel it off into two sheets after slitting both ears. On the other hand, when the softening temperature is higher than 190 ° C, the stretching flexibility and ultrasonic adhesive strength of the tape are poor. If the Shore A hardness is less than 70, the inflation tube is likely to be blocked during film formation, making it difficult to peel it off into two sheets after slitting both ears. On the other hand, when the Shore A hardness is more than 88, the elasticity of the tape and the ultrasonic adhesion become poor.

The ethylene-propylene-diene copolymer (b) used in the present invention is a copolymer containing ethylene, propylene and a diene compound. Examples of the diene compound include ethylidene norbornene, 1,
4-hexadiene, dicyclopentadiene and the like.
The ethylene-propylene-diene copolymer rubber (EP
DM) preferably has an ethylene content of 60 to 70 mol%, a propylene content of 30 to 40 mol%, and a diene compound content of 1 to 10 mol%. A more preferable range is 62 to 66 mol% for ethylene, 33 to 37 mol% for propylene, and 3 to 6 mol% for a diene compound. The number average molecular weight of the ethylene-propylene-diene copolymer is preferably 400,000 to 600,000, and the density is preferably 0.87 g / cm ³ or less. Furthermore, the ethylene-propylene-diene copolymer has a melt index (190 ° C, 2.16 kg load) of 0.1 to 1
It is preferably in the range of 2.0 g / 10 minutes, more preferably 0.3 to 5.0 g / 10 minutes.

The low-density polyethylene-based resin (c) used in the present invention is a homopolymer of ethylene by a high-pressure method or a copolymer with ethylene as a main component and 20% by weight or less of a vinyl-based compound or the like, for example, ethylene- Examples thereof include vinyl acetate copolymers and ethylene-ethyl acrylate copolymers. It may be linear low density polyethylene. The density of the low density polyethylene resin is 0.93.
5 g / cm ³ or less is preferable, and the melt index (MI, 190 ° C., load 2,16 kg) is 0.0.
It is preferably 5 to 20 g / 10 minutes. Further, in a copolymer such as an ethylene-vinyl acetate copolymer, the content of vinyl acetate is preferably 5 to 25% by weight, more preferably 5 to 15% by weight, and the melt index (MI, 19
0 ° C., load 2,16 kg) is preferably 0.1 to 20 g / 10 minutes, more preferably 1 to 5 g / 10 minutes.

The blending ratio of each component in the composition used in the present invention is as follows: (a) 60 to 80% by weight of a thermoplastic polyurethane resin having a softening temperature of 170 to 190 ° C. and a Shore A hardness of 70 to 88 degrees, (b) ) Ethylene-propylene-
It is 10 to 30% by weight of the diene copolymer and 10 to 30% by weight of the low density polyethylene resin (c). When the amount of the thermoplastic polyurethane resin (a) having a softening temperature of 170 to 190 ° C. and a Shore A hardness of 70 to 88 is less than 60% by weight, the properties of the polyurethane elastomer are lost and the texture is deteriorated. Abrasion resistance and mechanical strength decrease. On the other hand, if it exceeds 80% by weight, the inflation tube is likely to be blocked, and it becomes difficult to peel it off into two pieces after slitting both ears. (B) When the ethylene-propylene-diene copolymer is less than 10% by weight,
Insufficient stability in film formation of the film. on the other hand,
If it exceeds 30% by weight, the product tape is inferior in stretch flexibility, ultrasonic adhesiveness, rubber elasticity (large hysteresis strain after 100% stretch). When the blending ratio of the low-density polyethylene-based resin (C) is less than 10% by weight, the inflation tube is likely to block, and it becomes difficult to peel it off into two sheets after slitting both ears. On the other hand, when the content is 30% by weight or more, the product tape is inferior in stretch flexibility, ultrasonic adhesiveness, rubber elasticity (large hysteresis strain after 100% stretch). In addition to the above-mentioned components, an antioxidant, an ultraviolet absorber, a coloring agent, an inorganic filler, etc. can be appropriately added to the composition of the present invention.

In the present invention, after the above composition is formed into a film, the composition is 1.2 ° C. at a temperature of 60 ° C. or lower, preferably 50 ° C. or lower.
It is uniaxially stretched at least twice, preferably 1.3 to 4.0 times, and stress relaxation of at least 30% is performed at the same temperature or less. The composition is added with each of the above-mentioned constituents and, if necessary, other components, and dry-blended in advance using, for example, a Henschel mixer or a high-speed mixer, and then heated, for example, 1
It is obtained by melt-kneading with an extruder or the like at about 80 to 220 ° C. and extruding into pellets. The method for producing a film from the composition can be a flat film by a T-die extruder, which is a known method for forming a polyolefin film, and can be formed into a flat film. Considering (improvement in productivity) and the like, the air-cooled inflation method in which a tube-shaped film is formed by the inflation method is preferable. In the inflation molding method using the air-cooling method, it is preferable that the resin temperature is 180 to 220 ° C. and the blow ratio is 2.0 to 5.0. The thickness of the film is appropriately selected according to various uses, but is usually 10
It is preferable to mold in the range of 200 μm, preferably 50 to 150 μm. If the film thickness is less than 10 μm, the ultrasonic adhesive force with the PP nonwoven fabric or the like is poor. Also, 2
If it exceeds 00 μm, the tape feels hard and the texture is poor. In the film forming, the composition is
In the air-cooled inflation method, it is possible to stabilize the bubbles required for thinning and high-speed molding, and to reduce the blocking property without deteriorating the characteristics of the thermoplastic polyurethane resin.
The obtained film is uniaxially stretched at a temperature of 60 ° C. or lower, preferably 50 ° C. or lower, in a range of 1.2 times or more, preferably 1.3 to 4.0 times, preferably longitudinally uniaxially stretched, and the same 60 ° C. or less, preferably After annealing (stress relaxation) for at least 30% or more at a temperature of 50 ° C. or less, slitting into a predetermined width and winding it onto a bobbin to obtain a tape-shaped product. Stretching temperature is 60
If the temperature is higher than 0 ° C, vertical wrinkles are likely to occur in the film during tape production, and uniform stretching becomes difficult. Therefore, stretching is performed at a temperature of 60 ° C or lower. If the draw ratio is less than 1.2 times, the feel of the tape will be hard, the texture will be poor, the stretchability will be excellent, and it will be difficult to obtain a product with a small residual strain of expansion and contraction. However, since problems such as inferior ultrasonic adhesive strength occur, the draw ratio is 1.2 times or more, preferably 1.3.
Uniaxially stretched in a range of up to 4.0 times. Similarly, if the annealing temperature also exceeds 60 ° C., vertical wrinkles are likely to occur in the film during tape production, and problems such as strain after annealing relaxation are likely to occur. If the tape thickness is less than 10 μm, the ultrasonic adhesive strength with the PP non-woven fabric or the like is poor. Also,
If it exceeds 200 μm, the feel becomes hard and the texture is poor. In the above, further, when the product is aged at a temperature of 80 ° C. or lower for 3 to 72 hours, the elongation hysteresis strain at 200% or lower is lowered, and the texture is even better.
It is possible to obtain a tape having excellent stretchability. Tape is
Rich in elasticity, strain at 100% elongation is less than 10%,
Small residual strain of expansion and contraction, strength at 30% elongation is 100 gf
/ 5 mm less strength at low stress, good texture, moderate strength, ultrasonic welding with PP nonwoven fabric, etc., ratio of ethylene-propylene-diene copolymer and low density polyethylene resin Therefore, since the tape is light, does not easily discolor, and is inexpensive, it can be widely used as a simple mask string, diaper gather, natural rubber string substitute, etc.

[0010]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. The test methods in Examples and Comparative Examples are as follows. (1) Shore hardness (JIS A); JIS K630
Complies with 1. (2) Softening temperature; by a gear oven method (sheet thickness 300 μm). (3) Strength at 30% elongation; conforming to JIS L1096. (4) Strength at 100% elongation; conforming to JIS L1096. (5) Hysteresis strain after 100% elongation; JIS L
Complies with 1096. (6) Elongation at break: In accordance with JIS L-1096. (7) Feeling test (stretching flexibility): Five panelists and five grades. The best one is indicated by ⊚, the good one is indicated by O, the slightly inferior one by Δ, the inferior one by X, and the poor one by XX. (9) Ultrasonic adhesion: BRANSON ULTRASO
Using an ultrasonic welding machine manufactured by NIC DIV (frequency 20k
hz, welding time 0.15 seconds, pressure 2 kg / cm ² ),
Similar to the above-mentioned feeling test, the adhesive strength was evaluated by 5 panelists, and the best one was evaluated as ⊚, the best one as O, the slightly inferior one as Δ, the inferior one as X, and the poor one. Is indicated by XX.

Embodiment 1. 60 wt% of an ester thermoplastic polyurethane (Grade P-327 manufactured by Dainichiseika Kogyo KK, hereinafter referred to as PU) having a Shore hardness of 85 degrees and a softening temperature of 187 ° C., and an ethylene-propylene-diene copolymer ( Exxon Chemical Co., Ltd. product name Histalon V3708)
15 wt% and high pressure method low density polyethylene ((density 0.
935g / cm ³ Nippon Unicar Co., Ltd. grade NU
C8506) 25 wt% and a film thickness of 130% by using an air-cooled inflation film forming apparatus.
μm, folding width 820 mm (pro-up ratio: 3.5)
The inflation film of No. 1 was prepared, and both ears were slitted into a sheet to obtain a wound sample (hereinafter referred to as Sample 1). Next, this sample 1 was subjected to 2.0 at a stretching temperature of 35 ° C. using a vertical uniaxial roll stretching machine.
After stretching twice, at a temperature of 50 ° C., after relaxing 50% on the same line, it is passed through a slitter device for tape production, slit into a width of 5 mm, and a tape-like sample having a tape thickness of 120 μm (hereinafter, Sample-2) was obtained. At the same time as evaluating the physical properties of the tape, it was ultrasonically welded to a polypropylene (PP) non-woven fabric having a basis weight of 40 g / m ² by an ultrasonic welding machine, and the adhesive force and feel were measured, and the results are shown in Table 1. It was

Example 2. The physical properties of the tape obtained by further aging the sample 2 obtained in Example 1 at room temperature (23 ° C.) for 72 hours were evaluated, and at the same time, an ultrasonic welding machine was used to measure polypropylene (PP) having a basis weight of 40 g / m ^2. It was ultrasonically welded to a non-woven fabric, and the adhesive force, touch and the like were measured, and the results are shown in Table 1.

Embodiment 3. Further, the physical properties of the tape obtained by aging the sample 2 obtained in Example 1 at 50 ° C. for 72 hours were evaluated, and at the same time, a polypropylene (PP) having a basis weight of 40 g / m ² was measured by an ultrasonic welding machine.
It was ultrasonically welded to a non-woven fabric, and the adhesive force, touch and the like were measured, and the results are shown in Table 1.

Example 4. A tape was prepared in the same manner as in Example 3 except that the softening temperature and hardness of the ester-based thermoplastic polyurethane were changed to those shown in Table 1, and various physical properties of the tape were evaluated, and at the same time, using an ultrasonic welding machine. Was ultrasonically welded to a polypropylene (PP) non-woven fabric having a basis weight of 40 g / m ² , and the adhesive force and touch were measured, and the results are shown in Table 1.

Comparative Example 1. Ester thermoplastic polyurethane having a Shore hardness of 85 degrees and a softening temperature of 187 ° C. (Grade P-3 manufactured by Dainichiseika Kogyo Co., Ltd.) used in Example 1.
27) 60 wt% and ethylene-propylene-diene copolymer (Hexalon V3708, trade name, manufactured by Exxon Chemical Co., Ltd.)
A composition comprising 15 wt% and 25 wt% of high-pressure low-density polyethylene (NUC8506 manufactured by Nippon Unicar Co., Ltd.) was used in an air-cooled inflation film forming apparatus.
An inflation film having a film thickness of 130 μm and a folding width of 820 mm (pro-up ratio: 3.5) was prepared, and both ears were slitted into a sheet to obtain a wound sample (hereinafter referred to as sample 1). Next, an unstretched tape made of this sample 1 (thickness: 130 μm
m) various physical properties are evaluated and, at the same time, ultrasonic welding is performed with a polypropylene (PP) non-woven fabric having a basis weight of 40 g / m ² by an ultrasonic welding machine, and the adhesive force and feel thereof are measured,
The results are shown in Table 1.

Comparative Example 2. In Example 1, the sample 1 was stretched at a stretching temperature of 35 ° C. using a vertical uniaxial roll stretching machine.
In the same manner as in Example 1 except that the tape was stretched to 2.0 times, and was not relaxed by 50%. Obtain a tape-like sample of 105 μm, evaluate the physical properties of the tape, and at the same time, ultrasonically weld it to a polypropylene (PP) non-woven fabric with a basis weight of 40 g / m ² and measure its adhesive strength and feel. Then
The results are shown in Table 1.

Comparative Example 3. Ester thermoplastic polyurethane has a Shore hardness of 90 and a softening temperature of 18
A tape was prepared in the same manner as in Example 1 except that the tape having a temperature of 4 ° C. was used, and the physical properties of the tape were evaluated. At the same time, the tape was made of polypropylene (PP) having a basis weight of 40 g / m ² by an ultrasonic welding machine. It was ultrasonically welded to a non-woven fabric, and the adhesive force, touch and the like were measured, and the results are shown in Table 1.

[0018]

[Table 1]

From Table 1, the following can be understood. The tape shown in Example 1 has a 100% elongation strain (hysteresis strain) of 15% to 8%, which is lower than that of the tape shown in Comparative Example 1, indicating that the rubber elasticity is improved. (Normally used for mask string, diaper gather, band string, etc., the hysteresis strain after 100% expansion of the elastic body is
It is required to be 10% or less. ) Further, the tape strengths at 30% elongation and 100% elongation of the tape of Example 1 are lower than those of the tape of Comparative Example, and as shown in Table 1, since the tape is elongated by a relatively weak force. In addition, it seems that the touch was good and the elasticity of the touch test was also good. The tape shown in Example 2 was obtained by aging the tape shown in Example 1 at room temperature (23 ° C.) for 72 hours.
The strain at the time of elongation at 00% (hysteresis strain) is 7.0%, which is a slight improvement over the tape shown in Example 1. Other physical properties are almost the same as in Example 1, but
The ultrasonic adhesiveness with polypropylene non-woven fabric is further improved. The tape of Comparative Example 2 uses the same resin composition as in Examples 1 and 2, but if it is simply stretched twice, it will be wound around the bobbin as it is, and thus it will be 72 at room temperature. Even if left alone for about an hour, urethane crosslinking does not proceed so much over time, and therefore 100%
It seems that the hysteresis strain after elongation is not so much improved. In addition, the flexibility in stretchability and ultrasonic sealability (adhesiveness) in the feel test were also inferior. Example 3 is a tape obtained by aging the tape of Example 1 for 72 hours at 50 ° C., and the hysteresis strain after 100% expansion and contraction is further improved as compared with Examples 1 and 2. Recognize. Regarding other physical properties of the tape, Examples 1 and 2 were used.
As good as. In Example 4 and Comparative Example 3, the blending ratio of each component was constant, but the segment or hardness of the urethane used and the softening temperature were changed. For example, in Example 4, the soft segment and the hard segment are special polyester and MDI, respectively, which are the same as in Examples 1 to 3 and Comparative Examples 1 and 2, and the softening temperature of polyurethane is 18
It was a decrease at 0 ° C. The tape processing conditions are the same as in Example 3. This tape has a strain after 100% elongation, a 30% elongation strength, and a 100% elongation strength lower than those of Examples 1 to 3, and also has good stretch flexibility and ultrasonic adhesiveness in a touch test. On the other hand, in Comparative Example 3, the soft segment and the hard segment were the same, but the chain extender was changed, and at the same time, the hardness was 90 degrees (Shore A, JIS.
It is a hardened version of A). The tape processing conditions are the same as in Example 1. This tape is 30% and 100
Since the strength at low stress at the time of% elongation is strong, the feel at the start of stretching is hard, and the elongation at tensile rupture is low as in Comparative Example 2, and the feel is poor. Also, the ultrasonic adhesion to the PP non-woven fabric is poor.

[0020]

As described above, according to the present invention, excellent stretchability,
Stretching residual strain is small and the strength at 30% elongation is 100g
Less than f / 5 mm, low strength at low stress, good texture, moderate strength, ultrasonic welding with polypropylene (PP) non-woven fabric, light weight, less discoloration, inexpensive A tape and a manufacturing method thereof can be provided. The tape according to the present invention is excellent in stretchability, has a small residual stretch strain, has a good texture, has a suitable strength, and can be ultrasonically welded to a polypropylene (PP) non-woven fabric.
Since it is light, does not easily discolor, and is inexpensive, it can be widely used as a simple mask string, diaper gather, natural rubber string substitute, etc.

Claims (2)

[Claims] 1. A thermoplastic polyurethane resin having a softening temperature of 170 to 190 ° C. and a Shore A hardness of 70 to 88 degrees is 60 to 80% by weight, and (b) an ethylene-propylene-diene copolymer is 10 to 30% by weight. And (c) a composition containing 10 to 30% by weight of a low-density polyethylene resin, wherein the strain at 100% elongation is less than 10%. 2. A thermoplastic polyurethane resin having a softening temperature of 170 to 190 ° C. and a Shore A hardness of 70 to 88 degrees, 60 to 80% by weight, and (b) an ethylene-propylene-diene copolymer, 10 to 30% by weight. And (c) a composition containing 10 to 30% by weight of a low density polyethylene resin is uniaxially stretched 1.2 times or more at a temperature of 60 ° C. or less after molding into a film, and at least 30% at the same temperature or less. The stress at 100% elongation is 1 which is characterized by performing the above stress relaxation.
A method for producing an elastic tape, which is less than 0%.