JPH08336897A - Method for connecting stretchable film - Google Patents

Abstract

PURPOSE: To provided a new method for connecting the damage hole such as a pinhole of a stretchable urethane film without thermal shrinkage or blocking by external heat without conventional double structure becoming expensive. CONSTITUTION: A film 5 having the same properties as those of a film A is brought into contact with the hole of an urethane film 2 (film A) having a damage hole 3, and the hole is pressed by an ultrasonic welder having a spherical horn end is pressed via glass fiber woven fabric 6 of fluorine resin coating to connect the hole 3. Thus, an urethane foam molding monolithic vacuum molding back-up sheet can be formed without liquid leakage even from a raw fabric film having a pinhole which cannot be heretofore used, and even a single- layer film can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for repairing and joining a broken hole of a stretchable urethane film having a broken hole such as a pinhole.

[0002]

2. Description of the Related Art In the fields of automobiles, furniture, etc., a urethane film is attached to a woven fabric so that the mold is in contact with the woven fabric side, and this is used as a backup sheet.
BACKGROUND ART A urethane liquid is poured into a mold and foamed to manufacture an integrally molded body of urethane foam and a woven fabric. As a backup sheet for such urethane injection foam integral vacuum forming, it is required that it has good adhesiveness with urethane foam, that it can be adhered to a base material to which the foam is joined, and that it has stretchability. Are often used.

Stretchable urethane films are often used as stretchable members such as disposable paper diapers and napkins.

However, since the thermoplastic polyurethane resin generally used as a raw material for the stretchable urethane film is generally hygroscopic, when it is formed into a film or the like, it is foamed by the absorbed water, which causes a hole to be formed. Easy to obtain a film.

In order to avoid this, a method of drying the raw material in advance with a dehumidifying dryer or the like to reduce the water content to 500 ppm by weight or less is generally performed before the film formation and the like. However, in the case of forming a thin film having a thickness of 40 μm or less, even if the generation of pores can be reduced by performing such control, it is impossible to eliminate it.

The size of the above-mentioned holes is mostly from 1 mmφ pinhole to 10 mmφ, and the urethane film having such a broken hole also contains a liquid when performing the urethane injection foaming integral vacuum forming. This will cause problems. In addition, when used for gathering diapers, there is a risk that the tape may be cut and trouble may occur.

In order to solve the above problems, it is necessary to repair the breakage holes, but it is difficult to repair the breakage holes in the stretchable urethane film. Usually, a two-layer film is formed with an adhesive layer interposed therebetween. Things are being used. Therefore, the cost is increased.

[0008] On the other hand, it has been attempted to bring a urethane film of the same quality as the urethane film into contact with the damage hole and melt-bond the damage hole by external heating. It becomes longer and the joint surface shrinks, and the finished state of the joint surface deteriorates. Further, since the film is generally handled in a state of being wound in a large amount, in addition to the winding tightening stress, the joint portion becomes sticky and is blocked due to thermal deterioration of the joint surface.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides a new joining method for a breakage hole of a stretchable urethane film which does not cause heat shrinkage or blocking due to external heating joining, instead of an expensive two-layer structure. The purpose is to

[0010]

Means for Solving the Problems As a result of intensive investigations, the inventors of the present invention have made a film of the same quality as the urethane film abut on the broken hole portion of the urethane film, and the tip is inserted through a special member. The present invention has been accomplished by finding that the object of the present invention can be achieved by pressing with a spherical ultrasonic welding machine.

That is, according to the present invention, a stretchable urethane film (hereinafter, referred to as film B) of the same quality as the film A is provided in the broken hole portion of the stretchable urethane film (hereinafter, referred to as film A) having a breakage hole. And a glass fiber fabric coated with a fluororesin is used to press the damage hole portion by an ultrasonic welding machine having a spherical horn tip to join the damage hole. The gist is the method of joining the stretchable urethane film.

The films A and B used in the present invention are made of the same material, and they are made of a thermoplastic polyurethane resin or a resin composition containing at least 40% by weight of the polyurethane resin.

Examples of the thermoplastic polyurethane resin include long-chain polyols, short-chain polyols of polyester type, adipate type, polyether type, polycaprolactone type, etc.
By polyaddition reaction using diisocyanate as a raw material,
A polyurethane elastomer obtained through a urethane bond in the molecule is mentioned.

Examples of long-chain polyols include polyethylene glycol and polypropylene glycol, and examples of short-chain polyols include ethylene glycol and 1,4-
Examples of the diisocyanate include butanediol and 1,4-hexanediol. Tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate,
Hexamethylene diisocyanate and the like can be mentioned.

Such a thermoplastic polyurethane elastomer preferably has a softening temperature of 170 to 190 ° C. and a Shore A hardness (JIS A hardness) of 70 to 88. If the softening temperature is less than 170 ° C., the inflation tube is likely to block when the film is formed by the inflation method, and it becomes difficult to peel it off into two pieces after slitting both ears. On the other hand, when the softening temperature exceeds 190 ° C,
The stretch flexibility of the film becomes inferior. Further, when the Shore A hardness is less than 70, the inflation tube is apt to block when the film is formed by the inflation method, and it becomes difficult to peel it off into two sheets after slitting both ears. On the other hand, when the Shore A hardness exceeds 88, the stretch flexibility of the film becomes poor.

At least 4 thermoplastic polyurethane resins
A preferable example of the resin composition containing 0% by weight is a composition having the following composition.

(A) Thermoplastic polyurethane resin 40 to 7
0% by weight, (b) ethylene-propylene-diene copolymer 10 to 25% by weight (c) low density polyethylene resin 1
0 to 25% by weight (d) 5 to 20% by weight of a modified styrene elastomer modified with an unsaturated carboxylic acid or its derivative and having a styrene ratio of 30% by weight or less, and (e)
A thermoplastic polyurethane resin composition comprising 0 to 20% by weight of a styrene elastomer.

The above-mentioned (a) thermoplastic polyurethane resin is
It is selected from the above-mentioned thermoplastic polyurethane resins, but adipate-based polyurethane elastomers are particularly desirable.

(B) ethylene used in the above composition
The propylene-diene copolymer 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 (EPDM) 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 1.
It is preferably 10 mol%. A more preferable range is ethylene of 62 to 66 mol% and propylene of 33 to
37 mol% and the diene compound are 3 to 6 mol%.

The ethylene-propylene-diene copolymer has a number average molecular weight of 400,000 to 600,000 and a density of 0.87.
It is preferably g / cm ³ or less. Further, the copolymer has a melt index (MI; JIS K7210; 19).
0 ℃, 2.16kg load) is 0.1-12.0g / 1
It is preferably 0 minutes, particularly 0.3 to 5.0 g / 10 minutes.

The low-density polyethylene-based resin (c) used in the above composition is a homopolymer of ethylene by a high pressure method or a copolymer with 20% by weight or less of a vinyl-based compound as an ethylene main component, for example. Examples thereof include ethylene-vinyl acetate copolymers and ethylene-ethyl acrylate copolymers. It may be linear low density polyurethane.

The low density polyethylene resin preferably has a density of 0.935 g / cm ³ or less and a melt index (MI) of 0.05 to 20 g / 10 min.

The modified styrenic elastomer having a styrene content of 30% by weight or less, which is modified with the unsaturated carboxylic acid or its derivative (d) used in the above composition, is, for example, a styrene-based elastomer with an unsaturated carboxylic acid. Alternatively, it can be obtained by addition reaction of its derivative. As the styrene-based elastomer, a styrene-butadiene block copolymer or a styrene-isoprene block copolymer or a block copolymer having a polymer block mainly containing styrene and a polymer block mainly containing butadiene or isoprene. An elastomer obtained by hydrogenating the coalescence can be mentioned.
Specific examples thereof include styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-butene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SI).
S), styrene-ethylene-propylene-styrene block copolymer (SEPS) and the like.

Of these, hydrogenated compounds are preferable from the viewpoint of coloring and stability of physical properties.

As the styrene elastomer, one having a styrene ratio of 30% by weight or less is used. For example, by hydrogenating a styrene-butadiene-styrene block copolymer, a styrene-ethylene-butene-styrene block copolymer (SEBS) is obtained.
Ratio of styrene in composition ratio S / EB of styrene (S) and ethylene (E) -butene (B), that is, S / E
B + S of 30% by weight or less is used. Others are the same. When the ratio of the styrene exceeds 30% by weight, the obtained film becomes hard and the strain becomes large.

Examples of the unsaturated carboxylic acid or its derivative are maleic acid, fumaric acid, itaconic acid, acrylic acid, crotonic acid, endo-bi-cyclo [2,2,2].
1] -5-heptene-2,3-dicarboxylic acid, cis-4
Examples thereof include cyclohexene-1,2-dicarboxylic acid and their anhydrides and imidized products, and maleic anhydride is preferably used. The addition amount of the unsaturated carboxylic acid or its derivative is 5 to 10 mg CH ₃ O in terms of acid value.
Na / g is preferred.

As the styrene-based elastomer (e) used in the above composition, the styrene-based elastomer which is the base of the modified styrene-based elastomer of the above (d) can be used, and the styrene content is 30% by weight or less. Are preferable for the same reason as above.

The blending ratio of each component in the resin composition is as described above, but if the content of (a) the thermoplastic polyurethane resin is less than 40% by weight, the properties of the polyurethane elastomer are lost and the stretch flexibility deteriorates. Further, the properties of polyurethane such as abrasion resistance, heat resistance and mechanical strength are deteriorated. On the other hand, when it exceeds 70% by weight, the hot melt adhesiveness at high speed is deteriorated, and the inflation tube is apt to be blocked when the film is formed by the inflation method, and it becomes difficult to peel it off into two pieces after slitting both ears. .

When the content of the ethylene-propylene-diene copolymer (b) is less than 10% by weight, the stability of the film in the film formation becomes insufficient, and the elasticity of the product, hot-melt adhesiveness, rubber elasticity (100%). % Hysteresis strain after expansion and contraction) is poor. On the other hand, if it exceeds 25% by weight,
When the film is formed by the inflation method, the inflation tube is easily blocked, and it becomes difficult to separate the two tubes after slitting both ears.

When the blending ratio of (c) the low-density polyethylene resin is less than 10% by weight, when the film is formed by the inflation method, the inflation tube is likely to block and it is difficult to peel it off into two sheets after slitting both ears. Become. On the other hand, when it is 25% by weight or more, the elasticity of the product, the rubber elasticity (the hysteresis strain after 100% expansion and contraction is large) and the like are poor.

If the blending ratio of the (d) modified styrenic elastomer is less than 5% by weight, the hot melt adhesiveness is poor and the film formation becomes difficult. on the other hand,
When it exceeds 20% by weight, discoloration and mechanical strength are reduced.

(E) The styrene elastomer is 0 to 2
The addition of 0% by weight makes it possible to improve the hot melt adhesiveness. However, if it exceeds 20% by weight,
Film formability and mechanical strength of the film are reduced.

In particular, the total compounding ratio of (d) modified styrene elastomer and (e) styrene elastomer is 15
When the content is at least% by weight, the effect of improving the hot melt adhesiveness becomes greater, which is preferable.

In addition to the above-mentioned respective constituents, the resin composition may appropriately contain other components such as an antioxidant, an ultraviolet absorber, a coloring agent and an inorganic filler. Even when the thermoplastic polyurethane resin is used alone as a raw material,
You may mix | blend these other components as needed.

The composition is prepared by adding each of the above-mentioned constituents and, if necessary, other components, and preliminarily dry blending with a Henschel mixer or a high speed mixer.
It is obtained by melt-kneading and extruding into pellets under heating at about 180 to 230 ° C. using an extruder or the like.

The stretchable urethane film used in the present invention is formed as a flat film by a T-die extruder, which is a known method for forming a polyolefin film from the thermoplastic polyurethane resin or the resin composition as a raw material. However, considering the strength balance between the vertical and horizontal strength of the film and the high-speed moldability (improvement in productivity) in thin film, the film is formed by the inflation method, which is formed as a tubular film, especially the air-cooled inflation method. Those that are preferred are. In the air-cooled inflation method, the resin temperature is preferably 180 to 220 ° C. and the blow ratio is preferably 2.0 to 5.0. The thickness of the film is appropriately selected according to various uses, but is usually 150.
It is preferable to mold to less than μm. Film thickness is 150
When the thickness exceeds μm, heat transfer is poor when the film A and the film B are joined together through a glass fiber fabric coated with a fluororesin. In the above film forming, a film is prepared by an air-cooled inflation film forming apparatus and slit into a predetermined width to obtain a rolled product. You may go through a stretching process.

Needless to say, a commercially available stretchable urethane film can be used in the present invention.

Next, an example of the method of the present invention will be described with reference to the drawings. As shown in FIG. 1, for example, a film A2 is placed on a stand 1 made of a releasable material such as a silicone rubber sheet, and the damage hole 4 has a sufficient size to close the damage hole 3. The patch-shaped film B5 is brought into contact, and these films 2 and 5 are pressed by an ultrasonic welding machine (not shown) through the glass fiber woven fabric 6 coated with a fluororesin.

The base 1 is replaced with a silicone rubber sheet,
It may be made of a material having elasticity and peelability as in the case of other materials. A heat insulating member (not shown) such as thick paper may be laid under the table 1.

In the present invention, any type of ultrasonic welding machine such as a pencil type can be used, but the tip of the horn must be spherical. As shown in a comparative example described below, joining cannot be satisfactorily performed when the tip has a shape other than a spherical shape. This is because ultrasonic welding requires high parallelism between the horn and the ground plane, and even if the parallelism is slightly shifted, the amplitude of the horn concentrates at one point, and as a result, a hole opens at that point. Because. On the other hand, if the tip of the horn is made spherical, the shape of the grounding surface is constant even if the parallelism is deviated, and it is considered that such an adverse effect can be avoided.

The frequency of ultrasonic waves required for welding in the present invention is
15 to 50 kHz is sufficient.

In the present invention, film A2 and film B5
Glass fiber woven fabric 6 coated with fluorine resin
It is necessary to press with an ultrasonic welding machine through.
With a woven fabric made of glass fibers without coating with a fluororesin, the releasability is insufficient, and it becomes difficult to bond and repair the film. Further, as shown in Comparative Examples described later, when the glass fiber fabric 6 is not used for extrusion, the object of the present invention is not achieved at all.

[0043]

As described above, in the method of the present invention utilizing ultrasonic waves, since the heat generation bonding is caused by the molecular motion at the interface of the bonding portion, the bonding surface has a good finished state and the bonding is performed in a short time. Therefore, the film A2 and the film B5 are not thermally deteriorated, and accordingly, deformation such as pulling due to shrinkage does not occur.

Since the surface of the glass fiber woven fabric 6 used at the time of bonding is uneven, the bonding surface is in an embossed state, and the bonding film is not thermally deteriorated. The resulting film is difficult to block even when wound in large quantities.

[0045]

The present invention will be described in more detail with reference to the following examples.

The evaluation methods in Examples and Comparative Examples are as follows.

(1) Water pressure resistance test: Based on the method A of JIS L1092, a water leak pressure method test was performed using a water resistance tester by means of water pressure. Raise the water level (speed: 10 cm
/ Min) Measure the water level when water leaks from one place, and measure 100
Samples that did not cause water leakage at a water level of 0 mm were marked with ◯, and others were marked with x, and unevenness in the bonded portion of the bonded film was confirmed.

(2) Bonding surface condition The condition of the bonding surface was visually observed, and the one in good condition was marked with ◯, the one with deformation and the one with holes were marked with x.

(3) Tensile strength of the joint part With respect to the test piece obtained by cutting the joint part into a square shape of 25 mm × 150 mm, using a tensile tester Strograph manufactured by Toyo Seiki Co., Ltd., a load cell of 5 kg and a chuck interval of 100 m
A tensile test was conducted under the conditions of m and crosshead speed of 300 mm / min to determine the strength at break of the test piece.

(4) Elongation of joint part Tested simultaneously with the tensile strength of (3) above, and the elongation at break of the test piece was obtained.

Example 1 Adipate thermoplastic polyurethane elastomer (Shore hardness: 85, softening temperature: 1)
87 ° C.) 47% by weight, ethylene-propylene-diene copolymer (propylene content: 27% by weight, iodine value: 1
2gI ₂ / 100g, Mooney viscosity ML 1 _{+ 8} , 120
℃: 51) 16% by weight, high pressure method low density polyethylene (density: 0.923 g / cm ³ , MI: 0.8 g / 10 minutes)
Hydrogenated product of styrene-butadiene-styrene block copolymer modified with 16% by weight of maleic anhydride (S
EBS) (S / EB ratio: 30/70, melt flow rate: 3.5 g / 10 minutes; load 5 kg, measured at 200 ° C.)
16% by weight and SEBS (melt flow rate: 10 g
/ 10 min; load 2.16 kg, measured at 230 ° C.) 5 wt% was melt-kneaded to obtain a thermoplastic polyurethane resin composition. Using this composition as a raw material, an air-cooled inflation film forming apparatus was used to prepare a film having a thickness of 30 μm and a folding width of 1,100 mm, slitting both ears, and wound into a sheet shape to obtain a raw material having a width of 1,050 mm. I got a film.

Next, intentionally add 5 mmφ to this original film.
With respect to the film A having the holes, the holes were repaired and joined by the following method.

First, as a base, the width of the lower side is 1,100 m
A commercially available silicone rubber sheet having m, a length of 300 mm and a thickness of 5 mm was laid. The film A is placed on the sheet, and the original film is further placed on the outer peripheral portion of the hole.
Place a patch made of film B cut out in mmφ,
A Teflon glass cloth sheet (manufactured by Nippon Chemifab Co., trade name Chemiglass 400-3) having a length of 250 mm, a width of 250 mm and a thickness of 60 μm is placed on the patch, and a pencil type ultrasonic hand welder (manufactured by Nippon Future Co., Ltd.) is placed thereon. , Type: W2005-28, Frequency: 28k
Hz), press a horn with the following specifications with a pressing force of 800 g, and stroke the outer circumference of the patch corresponding to the outer circumference of the hole lightly in several circles, then remove the Teflon glass cloth sheet and bond the film. Got

Material: titanium, amplitude: 84 μm, shape:
Spherical tip, size: 20mmφ / 10mmφ, L = 10
An evaluation test was conducted on the obtained bonding film, and the results are shown in Table 1.

(Example 2) Example 1 was repeated except that a commercially available stretchable urethane film (trade name: Silklon, manufactured by Okura Industry Co., Ltd.) was used in place of the raw film in Example 1.
A bonding film was obtained in the same manner as in. An evaluation test was conducted on this film, and the results are shown in Table 1.

Comparative Example 1 A bonding film was obtained in the same manner as in Example 1 except that the horn having the following specifications was used. An evaluation test is conducted on this film,
The results are shown in Table 1.

The pressing method of the horn in this case is as follows.
The horn was fixed by using a jig so that the tip of the horn was in horizontal contact with the film surface.

Material: titanium, amplitude: 84 μm, shape:
Tip 10 mmφ cylindrical, tip surface flat, size: 20 mmφ / 10 mmφ, L = 10
0 mm (Comparative Example 2) A bonding film was obtained in the same manner as in Example 1 except that the horn having the following specifications was used. An evaluation test was conducted on this film, and the results are shown in Table 1.

The horn pressing method in this case is as follows.
It carried out similarly to the comparative example 1.

Material: titanium, amplitude: 84 μm, shape:
Tip 10 mmφ cylindrical, tip surface irregularity (0.5 mm embossed), size: 20 mmφ / 10 mmφ, L = 100
mm (Comparative Example 3) A bonding film was obtained in the same manner as in Example 1 except that the Teflon glass cloth sheet was not used. An evaluation test is conducted on this film,
The results are shown in Table 1.

[0061]

[Table 1]

[0062]

EFFECTS OF THE INVENTION It is possible to easily and stably bond a broken hole of a urethane film in a short time. Therefore, it has become possible to use a urethane film having a broken hole which cannot be used conventionally. Therefore, since the loss at the time of forming the urethane film can be reduced, the production efficiency is improved and the yield is increased.

Further, since the finished state of the joining surface was good, there was no thermal deterioration, and the joining surface was in the embossed state, blocking in the large volume winding tape was eliminated.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining a method of the present invention.

[Explanation of symbols]

 1 unit 2 Film A 3 Damaged hole 4 Damaged hole outer periphery 5 Film B 6 Fluororesin coated glass fiber woven fabric

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B29L 7:00

Claims (2)

[Claims] 1. A stretchable urethane film (hereinafter referred to as film A) having the same quality as that of the film A is brought into contact with the broken hole portion of a stretchable urethane film (hereinafter referred to as film A) having breakage holes, Stretchable urethane characterized in that the broken hole is pressed by an ultrasonic welding machine having a spherical horn tip through a glass fiber woven fabric coated with a fluororesin to join the broken hole. How to join films. 2. The film A and the film B contain at least 4 parts of a thermoplastic polyurethane resin or the urethane resin.
The method for joining stretchable urethane films according to claim 1, wherein the method comprises a resin composition containing 0% by weight.