JPH0559337A - Hot-melt adhesive - Google Patents

Abstract

PURPOSE:To provide the title adhesive to be used, in the production of metallic center core-contg. flexible discs, for bonding between the disc and core. CONSTITUTION:The objective hot-melt adhesive can be obtained by incorporating (A) 100 pts.wt. of a synthetic rubber-based resin with (B) 30-500 pts.wt. of a tackifier and (C) 0-300 pts.wt. of wax. The present adhesive, which is to be used for bonding between a flexible disc and a metallic center core, is excellent in heat resistance and flexibility, enabling reliable bonding, leading to facilitating automatic process realization for the production of center core-bearing flexible discs.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible disk used in a personal computer, a word processor or the like, which is used in the manufacture of a flexible disk having a metal center core. The present invention relates to a hot melt adhesive used for bonding cores. 2. Description of the Related Art Recently, a flexible disk having a diameter of 3.5 inches, which is the mainstream of flexible disks, has a metal core bonded to the center of a disk usually made of plastic such as polyethylene terephthalate. In the past, as the joining method, a bonding method using a double-sided tape has been generally used. However, in the above method, it is necessary to punch the double-sided tape on the concentric circles, which causes a problem that the process on the automatic line becomes complicated. On the other hand, some solvent-type adhesives are also used, but in that case, there was a problem that the solvent was scattered. SUMMARY OF THE INVENTION The present invention makes it easy to automate the production of a flexible disk having a metal center core, and is excellent in heat resistance and flexibility, and enables hot and reliable joining. It is intended to provide a melt adhesive. The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, the present invention is a synthetic rubber resin 100.
It is a hot melt adhesive for adhering a flexible disk and a metal center core, in which 30 to 500 parts by weight of a tackifier and 0 to 300 parts by weight of wax are mixed per part by weight. Hereinafter, the present invention will be described in more detail. The synthetic rubber resins used in the present invention include styrene-diene block copolymers such as styrene-isoprene block copolymers and styrene-butadiene block copolymers, or hydrogenated products thereof. SEBS (styrene-ethylene-butylene-
Styrene) -based block copolymer and SEPS (styrene-ethylene-propylene-styrene) -based block copolymer (hereinafter the styrene-diene-based block copolymer and its hydrogenated products are collectively referred to as rubber-based resin A), ethylene Propylene-based rubber and butyl-based rubber (hereinafter collectively referred to as rubber-based resin B) are preferable, and they can be used alone or in combination of two or more. SEBS block copolymers and SEPS block copolymers are more preferable because of their excellent heat resistance, and a mixture of the above rubber-based resin A and rubber-based resin B is particularly preferable. Resin A20-7
0% by weight and 80 to 30% by weight of rubber resin B are suitable. When the amount of the rubber-based resin A is less than 20% by weight, the heat resistance tends to be insufficient, while when the amount of the rubber-based resin B is less than 30% by weight, a rapid temperature change occurs with respect to the flexible disk to which the metal core is bonded. Is added, the flexibility to relax the strain generated in the adhesive layer is slightly inferior. Specific examples of styrene-isoprene block copolymers include Califlex TR-1107, Califlex TR-1111, Califlex TR-1112 and Califlex TR manufactured by Shell Kagaku Co., Ltd.
-1117 and the like, and examples of styrene-butadiene block copolymers include Califlex TR-1101 and Califlex TR-1102 manufactured by the same company.
Etc. Specific examples of SEBS block copolymers include Kraton G-1 manufactured by Shell Chemical Co., Ltd.
650, Clayton G-1652, Clayton G-16
57 and Kraton G-1726, and specific examples of the SEPS block copolymer include Septon 2002, Septon 2003, and Septon 2043 manufactured by Kuraray Co., Ltd. The ethylene propylene rubber is a copolymer of ethylene and propylene, or ethylene obtained by copolymerizing ethylene and propylene with a small amount of a third component such as 1,4-hexadiene, dicyclopentadiene or ethylidene norbornene. Examples include propylene terpolymer, ethylene propylene rubber EP-11 [Moonie viscosity (ML1 + 4, manufactured by Nippon Synthetic Rubber Co., Ltd.)
100 ° C) 40], ethylene propylene rubber EP-4
3 [Moonie viscosity (ML1 + 4,100 ° C) is 47] and ethylene propylene rubber EP-82 [Moonie viscosity (M
L1 + 4,100 ° C.) 38) or the like can be used. Examples of the butyl rubber include a copolymer obtained by copolymerizing isobutylene with several% of isoprene and a halide of the copolymer. Specifically, butyl rubber 065 [Moonie manufactured by Nippon Synthetic Rubber Co., Ltd. Viscosity (ML1 + 8,100
C.) 45] and butyl rubber 268 [Moonee viscosity (ML1 + 3,127.degree. C.) 55]. Examples of the tackifier include rosin tackifiers such as natural rosin, polymerized rosin, hydrogenated rosin, rosin ester and hydrogenated rosin ester; polyterpene resin,
Terpene-based tackifiers such as terpene phenolic resins and hydrogenated terpene resins; petroleum resin-based tackifiers such as aromatic petroleum resins, aliphatic petroleum resins, cyclopentadiene petroleum resins and hydrogenated petroleum resins. , Preferably a petroleum resin-based tackifier, and more preferably a hydrogenated petroleum resin-based tackifier. As described above, the compounding amount of the tackifier is 30 per 100 parts by weight of the synthetic rubber resin.
To 500 parts by weight, and more preferably 50 to 300 parts by weight. If the amount of the tackifier is less than 30 parts by weight, the adhesiveness between the flexible disk and the center core will be poor, and if it exceeds 500 parts by weight, the cohesive force of the adhesive will be reduced, resulting in poor adhesive strength and heat resistance. .. Specific examples of the rosin tackifier include gum rosin, wood rosin, ester gum A, ester gum H, Pencel A and Pencel C manufactured by Arakawa Chemical Industry Co., Ltd., and Foral 85 manufactured by Hercules Co., Ltd. , Foral 105 and Hentalin C,
Specific examples of the terpene tackifier include YS resin A-115, YS resin To-105, YS polystar T-115, YS polystar 2130, Clearon P-115 and Clearon M-125 manufactured by Yasuhara Chemical Co., Ltd. , Respectively. Examples of petroleum resin-based tackifiers include Escoletz 2101 [manufactured by Tonex Co., Ltd.], Quinton C-100 [Nippon Zeon Co., Ltd.
Alcon P-90, Alcon P-115, Alcon M-100 [above, manufactured by Arakawa Chemical Industry Co., Ltd.], Pico Pale 110SF (manufactured by Pico), Wing Tack 95, Wing Tack 115 (all Goodyear), Petrodine # 100, Petrodine # 120 [above, Mitsui Petrochemical Industry Co., Ltd.], Marukaletz H-800, Marukaletz H-790 [above, Maruzen Petrochemical Co., Ltd.], Escron N-100 and Escrystal A- 120 (above, manufactured by Nippon Steel Chemical Co., Ltd.) and the like. If desired, two or more of the above tackifiers may be combined for the purpose of maintaining the balance of compatibility, heat stability, color tone, cohesive strength, etc. of the adhesive composition. Next, the wax will be described. In the present invention, the wax is used for the purpose of increasing the fluidity and non-tackiness of the adhesive when heated and melting, and improving the cohesive force at room temperature. Examples of the wax that can be used include paraffin wax, microwax, and low wax. Examples include molecular weight polyethylene, low molecular weight polypropylene, and amorphous polyalphaolefin. The blending amount of the wax in the hot melt adhesive of the present invention is 0 to 300 parts by weight, and more preferably 30 to 200 parts by weight, based on 100 parts by weight of the synthetic rubber resin. When the amount of the wax exceeds 300 parts by weight, the flexibility of the obtained hot melt adhesive is lowered and the cold resistance and impact resistance are lost. As the paraffin wax and the microwax, commercially available products such as those manufactured by Nippon Oil Co., Ltd. and Nippon Seiro Co., Ltd. can be used. As the low molecular weight polyethylene, the softening point is 80 ° C. to 150 ° C. or less. Low molecular weight polyethylene is suitable, for example, Neowax L [manufactured by Yasuhara Chemical Co., Ltd.], Sunwax 151-P, Sunwax E-300 [above, Sanyo Chemical Industry Co., Ltd.],
ACPE-617, ACPE-629 (above, Allied Chemical Co., Ltd.), Hoechst wax PE520 (Hoechst Co.), etc. are mentioned. Also, as low molecular weight polypropylene, Viscole 550P, Viscole 660P
[Sanyo Chemical Co., Ltd.], Hoechst Wax PP (Hoechst Co.), Vistac L [Chiba Fine Chemical Co., Ltd.] and Sun Attack [Asahi Gosei Chemical Co., Ltd.]. Amorphous polyalphaolefin is a low molecular weight amorphous polymer obtained by copolymerizing propylene with ethylene, butene-1, etc., and there are commercially available products such as LEXTACK 2215 and LEXTACK 2115 [Ube Lexen Co., Ltd.]. .. Furthermore, a wax obtained by copolymerizing ethylene or propylene with an appropriate amount of maleic acid, vinyl acetate, acrylic acid, an acrylic acid ester, methacrylic acid, or a methacrylic acid ester may be used. The hot melt adhesive of the present invention contains the above synthetic rubber resin, tackifier and wax as essential components. In addition to these components, the melt viscosity of the adhesive is lowered and the melt coatability is improved. For the purpose of improvement, it is preferable to use a liquid hydrocarbon-based plasticizer in an amount of 200 parts by weight or less per 100 parts by weight of the synthetic rubber resin. The liquid hydrocarbon-based plasticizer is an oil generally referred to as a bulking oil or a process oil in the technical field of synthetic rubber. Typical examples thereof include liquid paraffin, and other examples include Shelf Rex [Shell Chemical Co., Ltd.]. ], Diana Process Oil PW-3
80 [Idemitsu Kosan Co., Ltd.], Daimalon, YS Oil [Yasuhara Chemical Co., Ltd.], Kuraprene LIR [Kuraray Isoprene Chemical Co., Ltd.], Idemitsu Polybutene 2000H [Idemitsu Petrochemical Co., Ltd.] and Nisseki Polybutene [Nippon Petrochemical] Co., Ltd.] and the like. The hot melt adhesive of the present invention, for the purpose of preventing dripping during melt coating and improving yarn breakage, improving the thermal stability of the adhesive composition during heating and melting, imparting thixotropy and coloring, Fillers such as talc, silica, calcium carbonate, carbon black, zinc white, titanium oxide, and inorganic pigments may be added, and in addition, an antiaging agent or an ultraviolet ray inhibitor may be added. The hot melt adhesive of the present invention is composed of the above components, but is 19 in terms of coatability on an adhesive substrate.
The composition preferably has a melt viscosity at 0 ° C. of 100,000 cps or less, and more preferably 500 to 5
It is 0000 cps. If it exceeds 100,000 cps, stringing or uneven application of the adhesive is likely to occur. Meanwhile, 500 cp
If it is less than s, the adhesive will easily flow out of the predetermined portion during coating and bonding. The preferred softening point (R & B formula) of the adhesive is 80 to 150 ° C. If the softening point is less than 80 ° C, when the floppy disk is stored in a high temperature environment, the adhesive portion will be defective due to extremely weak stress, while if it exceeds 150 ° C, the bondable time after melt coating becomes short. .. Adhesive strength is a peel strength of 5 kg at room temperature
It is preferably f / inch or more, more preferably −
It is preferably 0.5 kgf / inch or more in the temperature range of 10 ° C to 70 ° C. The adhesive of the present invention uses a kneader, which is a method of dissolving and mixing the above components at a temperature of 140 to 250 ° C., preferably in a nitrogen atmosphere, in a heating type melting and stirring tank by rotating stirring blades simultaneously or sequentially. Then, the respective components are kneaded, or kneaded by an extruder having a single-screw or twin-screw screw, and the like. The flexible disk and the center core are bonded by the hot-melt adhesive obtained by the above method, for example, using a hot-melt applicator, in the laminating portion of the preheated stainless steel center core, if necessary,
It can be carried out by a method of applying the above-mentioned adhesive, which is usually heated to 140 to 220 ° C., and superposing a flexible disk thereon by an automatic line or manually. As the hot melt applicator used at this time, a roll coater or a wheel coater for transferring and applying an adhesive, a nozzle type applicator, or the like can be used. A nozzle type applicator, which can be easily controlled by a robot, is preferable for automatic line formation. Further, it is also possible to make an automatic line by a method in which a nozzle type applicator is fixed and a center core is rotated, and in this case, the adhesive is preferably applied in a linear or dotted line. The present invention will be described in more detail with reference to the following examples and comparative examples. The evaluation of the adhesive obtained in each example was performed by the following method. I. Compatibility: When melted at 190 ° C., the presence or absence of separation was visually checked. B. Melt viscosity: According to JAI-7-1980.
It heated at 190 degreeC and measured with the B-type rotational viscometer. C. R & B softening point: Measured according to JIS K 2207 (petroleum asphalt softening point test method (ring and ball method)). D. Peel strength: 1 for SUS plate cut to a width of 25 mm
Apply the adhesive that was heated and melted at 90 ℃ in a string shape at 5gr / m,
Similarly, with respect to a test piece obtained by immediately pressing a PET film cut into a width of 25 mm, -10 ° C, 23 ° C and 70 ° C.
It was measured at ° C. The joint portion had an overlap of 10 mm. The pulling speed is 50 mm / min. E. Temperature rising creep: Measured according to JIS K 6844 (method for measuring adhesive softening temperature). Using a test piece prepared in the same manner as the peel strength, a load of 100 gr was applied and held in an oven, the temperature was raised at a rate of 2 ° C. for 5 minutes, and the temperature at which the joint was broken was measured. F. Adhesion: Stainless steel center core (30
(mmφ) on a concentric circle with a radius of 14mm from the center, and apply adhesive melted at 190 ° C with a coating amount of 0.1g / m, and after 1 second, a flexible disk made of polyethylene terephthalate (5inchφ) coated with a magnetic recording medium. ) Is crimped and 50
The deformation distance at the end of the core was measured with a gauge after being placed in an atmosphere of ° C x 98% RH for 24 hours. Examples 1 to 7 Adhesives were produced by using the components shown in Tables 1 and 2 by the following procedure. That is, in Example 1, a 10 liter kneader heated to 200 ° C. in a nitrogen atmosphere was placed in a synthetic rubber resin such as Kraton G-1.
652; 0.5 kg and ethylene propylene rubber;
5 kg, tackifier Alcon P-115; 1 k
and 50 g of the antioxidant Irganox 1010 (manufactured by Ciba Geigy); and melt mixed for 30 minutes. Then, the sun attack, which is a wax; 0.5 kg
And Viscole 660P; 0.5 kg were added, and the mixture was melt-mixed for another 30 minutes. After that, the tackifier Y
1 kg of S Polystar 2130 and 0.8 kg of Idemitsu Polybutene 2000H, a liquid hydrocarbon plasticizer, were added,
Melt mixed for 1 hour. An adhesive was obtained after degassing under reduced pressure for about 30 minutes at a temperature of 200 ° C. The results of measuring the above physical properties of the obtained adhesive are shown in Table 1. Also in Examples 2 to 7, the same operation as in Example 1 above was performed to obtain an adhesive, and the physical properties of the obtained adhesive were evaluated. The results are shown in Tables 1 and 2. [Table 1] [Table 2] Comparative Example An adhesive was synthesized by using an ethylene-vinyl acetate copolymer instead of the synthetic rubber resin used in the above examples. That is, Evaflex 220 manufactured by Mitsui-DuPont Polychemical Co., Ltd. was used as the ethylene-vinyl acetate copolymer, and the ethylene-vinyl acetate copolymer; 10
0 parts by weight, tackifier YS Polystar 2130; 100
By weight, 50 parts by weight of wax viscol 660P, 50 parts by weight of liquid hydrocarbon plasticizer Idemitsu Polybutene 2000H and 5 parts by weight of Irganox 1010 were melt mixed to obtain an adhesive. The physical properties and adhesive performance of the above adhesive were as follows. Compatibility: good, melt viscosity:
3,500, Softening point: 85 ℃, Peel strength (Kgf / inch): 0.
1 (-10 ° C), 1.2 (23 ° C), almost 0 (70 ° C), temperature rising creep: 40 ° C, adhesiveness: 1.0mm As above, when ethylene-vinyl acetate copolymer is used No sufficient adhesion performance was obtained. According to the hot melt adhesive of the present invention,
It is possible to bond the metal center core and the flexible disk to each other in a short time without using a solvent without deteriorating the reliability of the joint portion. Furthermore, according to hot melt adhesion using this adhesive, the manufacturing process of the flexible disk with the center core can be easily automated.

Claims (1)

Claims: 1. A tackifier, 30 to 500 parts by weight, and a wax, 0 to 300, per 100 parts by weight of a synthetic rubber resin.
A hot melt adhesive for adhering a flexible disk and a metal center core, which is made up of parts by weight.