JPH0414624B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a composite heat insulating material used as a lining material for the main body or door of a refrigerator. The composite heat insulating material of the present invention is a heat insulating material having a structure in which urethane foam and a sheet of polyolefin resin or styrene resin are firmly adhered. [Conventional technology] The main body and doors of refrigerators are made of baked-on stainless steel or steel plates, and are coated with acrylonitrile-butadiene-styrene copolymer, which is a styrene resin, to prevent rust on the structural base material (outer frame) and to form shelves. It is equipped with a lining material obtained by vacuum forming, pressure forming, or forming using a combination of vacuum and pressure forming (hereinafter, these forming methods are collectively referred to as differential pressure forming) from a composite (commonly known as "ABS") sheet. . Furthermore, attempts have been made to use polypropylene lining materials with excellent surface gloss and low water absorption in place of ABS lining materials. In order to improve the heat insulation properties of refrigerators, it has been proposed to interpose urethane foam between the baking-painted stainless steel plate, which is the structural base material of the refrigerator, and the lining material, but it is difficult to obtain such a laminated structure. When a polyolefin resin sheet is used as the lining and exterior material, it is necessary to strengthen the adhesion between the polyolefin resin sheet and the urethane foam, which is a heat insulating material. For this purpose, the interior and exterior materials, which have been differential pressure molded in advance, and the urethane foam are laminated using liquid acrylic adhesive or epoxy adhesive, and then this laminated material is baked with adhesive applied to the inside. This is done by inserting and crimping the coated stainless steel into a structural base material (formwork), but a method that involves multiple steps would be expensive. Therefore, as shown in FIG.
It is preferable to use an on-site construction method in which a multi-layered structure in which the formwork 1, the urethane foam 4' and the lining material 2 are integrated is manufactured by injecting the foam, followed by foaming and curing. Furthermore, it is possible to apply an organic solvent-based adhesive to the polyolefin resin sheet in advance, let it dry, and then bond it to the urethane foam, which is an insulating material. Unfavorable for work environment. Furthermore, before differential pressure molding a polyolefin sheet, it is necessary to wipe off dust adhering to the surface of the sheet with a cloth or the like. As a way to solve this,
This problem can be solved by kneading an antistatic agent into the resin of the sheet material and using a sheet made of this, but the method of kneading the antistatic agent into the resin,
The antistatic function cannot be imparted to the sheet unless the sheet is stored for 30 to 50 days after forming the sheet before the antistatic function is imparted to the surface of the sheet.
On the other hand, it is necessary to take care to ensure that the sheet storage period is not affected by dust, which is not a good idea. The present inventors have studied various coating-type adhesive compositions that satisfy the required performance when manufacturing laminated structure insulation materials of urethane foam and ABS or urethane foam and polypropylene by on-site construction methods, and first We provided a composite heat insulating material with a structure in which a molded product of polyolefin resin or styrene resin and urethane foam are laminated with an adhesive containing the following components (A) and (B) (Patent Application No. 136344/1989) No., same
58-206807). Adhesive composition: (A) 20-80% by weight of a water-soluble polyimine compound selected from the group consisting of polyethyleneimine, poly(ethyleneimine-urea) and ethyleneimine adducts of polyamine polyamides (B) The following having antistatic properties: A water-soluble polymer consisting of an amphoteric compound obtained by modifying the tertiary nitrogen atom of a polymer consisting of components (a) to (c) with an amphoteric agent. 20-40% by weight 60-80% by weight (c) Other hydrophobic vinyl monomers 0-20% by weight [However, in each formula, R ¹ is H or CH ₃ , R ² and R ³ are each H or carbon number 1-2 an alkyl group, R ⁵ is an alkyl group having 1 to 18 carbon atoms,
A is an alkylene group having 2 to 6 carbon atoms]. [Problems with the Prior Art] This composite heat insulating material is made of a urethane foam firmly adhered to a polyolefin resin sheet or a styrene resin sheet, and is sufficiently practical as a refrigerator interior material. However, it was found that less than 10% of products had corners of vacuum-formed resin sheets with lower adhesive strength than other parts. [Specific means for solving the problems] The present invention was made to improve the drawbacks of the earlier invention, and uses resin sheets made of ethylene/acrylic acid copolymer, maleic anhydride grafted polypropylene, etc. By using a resin containing a carboxyl group to further improve the adhesive strength between the resin sheet molded product and the urethane foam, we can provide a composite heat insulating material that does not cause peeling of the resin sheet even under harsher conditions. . (Structure of the Invention) The present invention provides a composite heat insulating material having a structure in which a molded product of a carboxyl group-containing polyolefin resin and a urethane foam are laminated with an adhesive containing the following components (A) and (B). Adhesive composition: (A) 20-80% by weight of a water-soluble polyimine compound selected from the group consisting of polyethyleneimine, poly(ethyleneimine-urea) and ethyleneimine adducts of polyamine polyamides (B) Nitrogen atoms Contains 80-20% by weight of cationic or amphoteric acrylic polymers. (Resin) In the present invention, carboxyl group-containing polyolefins used as raw materials for resin sheet molded products include ethylene/acrylic acid random copolymer, ethylene/methacrylic acid random copolymer, acrylic acid grafted polyethylene, methacrylic acid grafted polyethylene, maleic anhydride. Acid-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene/vinyl acetate copolymer,
Examples include itaconic acid grafted polyethylene. In addition, resin compositions in which 5 to 20% by weight of these carboxyl group-containing polyolefins or styrene/maleic acid copolymers are blended with polypropylene, polyethylene, etc. can also be used, and in general, the latter is more suitable than using carboxyl group-containing polyolefins alone. The extrusion moldability of the sheet is better when the resin composition is used.
Good differential pressure moldability. The amount of carboxyl groups in the sheet containing the carboxyl group-containing polyolefin may be at least 1 x 10 ^-4 mol/g, preferably at least 3 x 10 ^-4 mol/g. This carboxyl group-containing polyolefin greatly contributes to improving adhesion with urethane. Since this carboxyl group-containing polyolefin is expensive, it is preferable to make the layer of the carboxyl group-containing polyolefin thin (1 to 30% of the wall thickness) and use it as a laminate with other unmodified resin. Resins for the sheet materials to be laminated include high-density polyethylene, low-density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-propylene copolymer,
Polyolefin resins such as propylene-butene copolymers; polystyrene, styrene-butadiene,
Styrenic resins include styrene block copolymer (so-called SBS), acrylonitrile-butadiene-styrene copolymer (so-called ABS), and high-impact polystyrene (so-called HIPS). These may be used alone or in combination of two or more. A stabilizer, an inorganic filler, a pigment, a rubber, etc. may be added to this resin. These resins are coextruded into a sheet together with the aforementioned carboxyl group-containing polyolefin, and if necessary, the front and/or back surfaces are subjected to corona discharge treatment to form a differential pressure molding sheet having a wall thickness of 0.3 to 4 mm. Next, as the water-based adhesive, a mixture of 20 to 80% by weight of the water-soluble polyimine compound as the component (A) and 80 to 20% by weight of the nitrogen atom-containing cationic or amphoteric acrylic polymer as the component (B) is used. This mixture is used as an aqueous solution with a concentration of 0.5 to 3% by weight. The above component (A), polyethyleneimine, a copolymer of ethyleneimine and urea [poly(ethyleneimine-urea)], or a polyamine polyamide with ethyleneimine added, is available from BASF in West Germany as Polymin SN, Polymin P, It is sold by Nippon Shokubai Kagaku Kogyo Co., Ltd. under the trade name Epomin P-100.
This polyimine compound (A) component greatly contributes to improving the adhesion with urethane. The nitrogen atom-containing cationic or amphoteric acrylic polymer of component (B) is water-soluble and greatly contributes to the anti-blocking and antistatic functions of the sheet. Such an acrylic polymer as component (B) can be produced by polymerizing a quaternized nitrogen-containing monomer or by quaternizing a tertiary nitrogen-containing polymer. Specific examples of nitrogen-containing monomers suitable for the present invention include the following. Here, in each formula, R ¹ is hydrogen or a methyl group,
R ² and R ³ are each a lower alkyl group (especially,
_C1 to _C4 , especially _C1 to _C2 ), ^R4 is a saturated or unsaturated alkyl group or benzyl group having 1 to 22 carbon atoms, X
is the quaternized counteranion of N (for example,
halide (especially chloride), A has 2 to 6 carbon atoms
represents an alkylene group. These nitrogen-containing water-soluble acrylic polymers with antistatic function are composed of these quaternary (amphoterized) nitrogen-containing monomers (b), (d), (d)′, (f), (f)′, ( blood),(
It can be obtained by homopolymerizing H)' and (G), or by copolymerizing these quaternary nitrogen-containing monomers with other vinyl monomers. In addition, tertiary nitrogen-containing monomers (a), (c),
(E) and (H) are homopolymerized or copolymerized with other monomers, and then quaternized with a cationizing agent such as alkyl halide, dimethyl sulfate, benzyl halide monochloroacetic acid ester, or monochloroacetic acid (salt).
It goes without saying that it can be made to exist in the polymer by amphotericizing it with an amphoteric agent such as propanesultone or propiolactone. Acrylic polymer with antistatic effect
Although (B) needs to be water-soluble, it is not desirable that it be excessively water-soluble. Therefore, this tertiary to quaternary nitrogen-containing polymer is preferably a copolymer with a hydrophobic monomer. Examples of the hydrophobic monomer include styrene or its substituted derivatives in the nucleus or side chain, acrylic or methacrylic acid esters, vinyl halides, and others. A particularly suitable nitrogen-containing water-soluble polymer (B) is an acrylic polymer obtained by copolymerizing the following components (a) to (c). (a) Monomers (a) to (f) 20 to 40% by weight 60 to 80% by weight [In the formula, R ¹ is H or a methyl group, R ⁵ is C ₁ to C ₁₈
(c) Other hydrophobic vinyl monomers 0 to 20% by weight. The most suitable water-soluble acrylic polymers are those in which monomer (a) is the monomer (f) described above and X is Cl. This water-soluble acrylic polymer is available from Mitsubishi Yuka Fine Co., Ltd. as ST-1000, ST-1100, ST-1300,
It is sold under the product name ST-3000. Heat resistance can be imparted to the antistatic film by further blending an epichlorohydrin adduct of polyamine polyamide with these components (A) and (B). This polyamine polyamide-epichlorohydrin adduct is a water-soluble, cationic thermosetting resin obtained by reacting a polyamide made from a saturated dibasic carboxylic acid having 3 to 10 carbon atoms and a polyalkylene polyamine with epichlorohydrin. Yes, it is sold under the trade name Kamain-557H by Deitzk Hercules and AF-100 by Arakawa Forestry Chemical Industry Co., Ltd. Further, other surfactants such as fluorine-based surfactants may be blended. These water-soluble polymers of component (A) and component (B) must be used in combination. On the other hand, the above ~
cannot meet the required performance. Usually (A)
20 to 80% by weight of ingredients solids, preferably 35 to 65%
In terms of weight%, component (B) is 80 to 20% by weight as a solid content.
Use at a ratio of These are used after being dissolved in water, a mixture of water and alcohol, such as ethanol or isopropanol, or a mixture of water, butyl cellosolve and alcohol. The adhesive is used as an aqueous solution or dispersion with a concentration of 0.1 to 10% by weight. It is useful to apply an antistatic agent to the side of the sheet opposite the adhesive side of the urethane foam.
Such an antistatic agent may be the same as the adhesive described above, or may be another antistatic polymer, such as the water-soluble antistatic acrylic polymer (B) described above. Additionally, this water-soluble antistatic polymer
(B), anionic surfactant, cationic surfactant, amphoteric surfactant, nonionic surfactant,
For example, lauryl aminopropionate sodium salt, stearyltrimethylammonium chloride, 1-hydroxyethyl-2-undecyl-
2-imidazoline ethylene oxide adduct,
nonylphenol ethylene oxide adduct,
It may also contain an antistatic agent such as lauryl sulfate tetrium salt or a fluorine-based surfactant. (Manufacture of composite heat insulating material) The aqueous solutions 2a and 2c of adhesives having an antistatic function containing these components (A), (B), and (C) are rolled,
Apply a coating of 0.01 to 1.0 to at least the back side of the sheet 2b that will be bonded to the urethane by brushing, spraying, etc.
g/m ² (solid content) and dried (see Figure 2). Adhesive resin films 2a, 2 thus obtained
The resin sheet with c on the front and back surfaces and on the back side to be bonded to urethane is subjected to normal differential pressure molding,
It is shaped into a shape suitable for refrigerator lining material. This shaped sheet 2 is perforated with a urethane solution 4 injection port 5 if necessary, and is inserted into a stainless steel or aluminum formwork 1, which is the outer structural base material of the refrigerator, as shown in Fig. 1. Then, from the injection port 5, for example, a two-component foaming urethane solution is poured into the cavity 4 formed by the mold 1 and the lining material 2.
The polyurethane foam 4' and the lining material 2 are injected into the lining material 2 and are injected into the lining material 2 to form a multi-layered lining material having a heat insulating property. Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that parts and percentages in the examples are based on weight. Example of manufacturing sheet 1 () Resin for glossy surface layer: MFR2.0g/10
A crystalline propylene homopolymer with a residual amount of 99% by weight after extraction with boiling heptane was used. () Resin used for deep drawing layer: 40% by weight of crystalline propylene-ethylene block copolymer with 5% ethene content, 0.5g/10 min MFR, 98% boiling heptane extraction residue, and 0.950g/cm density. ² ,
A composition consisting of 40% by weight of polyethylene with an MFR of 0.6g/10 minutes and 20% by weight of talc having a particle size of 1.5μ was kneaded using an extruder, extruded into a strand, and cut into pellets. () Resin on the side to be bonded to urethane: 15 parts by weight of polypropylene grafted with 0.65% by weight of maleic anhydride, 82 parts by weight of homopropylene polymer and 3 parts by weight of low-density polyethylene. A resin composition was used. The resin pellets for the deep drawing layer shown in () above have a diameter of 90.
A 3-layer multi-manifold die with a width of 700 mm was supplied at 230°C using a
A 40 mm extruder was used to feed the same die at 230 mm.
The temperature of the die was 230°C. The molten sheet extruded from the die was sequentially cooled and solidified using three rolls each having a width of 700 mm, and then subjected to corona discharge treatment to obtain a sheet for vacuum forming. The temperatures of the rolls were 80°C, 95°C, and 100°C starting from the roll closest to the die, and the rotational speed of the rolls was 1.5 m/min. The total sheet thickness is 1.6mm, and the glossy surface layer is 0.25mm.
The deep drawing layer (intermediate layer) was 1.10 mm, and the adhesive layer side with urethane was 0.25 mm. Example 2 Polypropylene “Mitsubishi Noblen” manufactured by Mitsubishi Yuka Co., Ltd.
MA-8" (trade name) as the surface gloss layer and maleic anhydride grafted ethylene/vinyl acetate copolymer (maleic anhydride grafting amount: approx. 1.2% by weight) as the urethane adhesive layer resin, coextruded at 230℃, A multilayer sheet with a thickness of 1.6 mm (surface gloss layer 1.56 mm, adhesive layer 0.04 mm) was obtained. Example 3 () Resin for gloss surface layer: MFR 2.0 g/10
A crystalline propylene homopolymer with a residual amount of 99% by weight after extraction with boiling heptane was used. () Resin for deep drawing layer (urethane adhesive layer): Polypropylene “Mitsubishi Noblen MH-6”
76 parts ethylene/acrylic acid random copolymer 10 parts styrene/butadiene/styrene copolymer 4 parts polystyrene 10 parts The resin for the deep drawing layer in () above was heated to 230°C using an extruder with a diameter of 90 mm to make two parts with a width of 700 mm. The resin for the glossy surface layer () was fed to the same die at 230°C using an extruder with a diameter of 40 mm. The temperature of the die was 230°C. The molten sheet extruded from the die was sequentially cooled and solidified using three rolls with a width of 700 mm, and then subjected to corona discharge treatment to obtain a two-layer vacuum forming sheet. The temperature of the rolls varies from 80℃ to 95℃ starting from the roll closest to the die.
The temperature was 100°C, and the rotation speed of the rolls was 1.5 m/min. The total sheet thickness is 1.6mm,
The surface gloss layer was 0.2 mm, and the deep drawing layer was 1.4 mm. Example 4 Polypropylene "Mitsubishi Noblen MH-8" 85 parts Maleic anhydride graft (1.2% by weight) Polypropylene 5 parts Ethylene-acrylic acid random copolymer 10 parts The above composition was extruded into a sheet at 230°C, then corona discharge treatment A sheet with a wall thickness of 1.6 mm was obtained. Example 5 Vinyltrimethoxysilane/ethylene random copolymer 40 parts Ethylene/acrylic acid random copolymer 10 parts Low density polyethylene 50 parts The above resin composition was extruded into a sheet at 200°C,
It was sequentially cooled and solidified using three rolls, and then subjected to corona discharge treatment to obtain a sheet for vacuum forming with a wall thickness of 1.6 mm. Example 6 (for comparison) () Resin used for gloss layer: MFR2.0g/10 minutes,
A crystalline propylene homopolymer with a residual amount of 99% by weight after extraction with boiling heptane was used. () Resin for deep drawing layer (intermediate layer): 40% by weight of crystalline propylene-ethylene block copolymer with ethylene content of 5% by weight, MFR of 0.5g/10 minutes, boiling heptane extraction residue of 98% by weight, and density
0.950g/cm ² , MFR 0.6g/10min polyethylene
A composition consisting of 40% by weight of talc and 20% by weight of talc having a particle size of 1.5μ was kneaded using an extruder, extruded into strands, and cut into pellets. The resin pellets for the deep drawing layer shown in () above have a diameter of 90.
The resin was supplied to a three-layer multi-manifold die with a width of 700 mm at 230° C. using a 40 mm diameter extruder, and the resin for the glossy layer in () was supplied to the same die at 230 mm using an extruder with a diameter of 40 mm. The temperature of the die was 230°C. The molten sheet extruded from the die has a width of 700 mm.
The mixture was sequentially cooled and solidified using a book roll, and then subjected to corona discharge treatment to obtain a three-layer vacuum forming sheet. The temperature of the rolls varies from 80℃ to 95℃ starting from the roll closest to the die.
The temperature was 100°C, and the rotation speed of the rolls was 1.5 m/min. The total sheet thickness is 1.6mm,
Each gloss layer was 0.20 mm and the deep draw layer was 1.20 mm. Example 7 (for comparison) Polypropylene “Mitsubishi Noblen” manufactured by Mitsubishi Yuka Co., Ltd.
MA-8" (trade name) was extruded into a sheet at 230°C, and then subjected to corona discharge treatment to obtain a sheet with a wall thickness of 1.6 mm. Manufacturing example of acrylic antistatic polymer of component (B) N, N -dimethylaminoethyl methacrylate
80 parts (0.5 mol), 50 parts (0.5 mol) of methyl methacrylate, and 200 parts of isopropyl alcohol were placed in a four-necked flask equipped with a stirrer, reflux condenser, thermometer, and dropping funnel, and after purging with nitrogen gas, , 0.9 part of 2'-azobisisobutyronitrile was added as a polymerization initiator, and the polymerization reaction was carried out at 80°C for 4 hours. Next, add 60 parts of monochloroacetic acid soda, and add 80 parts of sodium monochloroacetate.
After reaction (amphomerization) at ℃ for 6 hours, water was added while distilling off isopropyl alcohol to obtain an aqueous solution with a solid content of 35%. This acrylic polymer (hereinafter referred to as "ST") is is included in the molecular chain. Example 1 Both sides of the three-layer sheet obtained in Example 1 were coated with 35% of the acrylic polymer obtained in the above example and 65% of BASF's ethyleneimine adduct "Polymin SN" of polyamine polyamide (solid content ratio). A 1% aqueous solution of the mixed polymer (2) was applied to each of the front and back surfaces at a ratio of 0.3 g/m ² (solid content) and air-dried. The surface resistivity value of this sheet measured at 20° C. and 60% relative humidity was 6.5×10 ⁸ Ω·cm, and the anti-blocking property was normal. Using a vacuum/pressure forming machine, this sheet is made into approximately 230
It was introduced into a heating furnace set at ℃ and compressed air (5.0Kg/cm ² )
Plug assist molding was carried out using a combination of pressure and reduced pressure (-600 mmHg) (drawing ratio H/D = 1/1). The release properties of the sheet were good, and the plug was easily separated from the sheet. After drilling an injection port in a part of this shaped sheet, this sheet is inserted into a stainless steel frame that is the frame of the refrigerator body, and then the space (cavity) formed by the frame and the shaped sheet is inserted. When a two-component foaming urethane solution "HM-1510" (trade name) manufactured by Polyurethane Kagaku Kasei Co., Ltd. was injected into the space from the injection port, foaming started after 10 seconds, and after 1 minute, the space was filled with urethane. Completely filled with foam.The density of this urethane foam is 0.05g/cm ²
It was hot. Repeat the same operation 20 times and prepare 20 samples.
I got one. After 24 hours, the flat and corner portions of the sheet to which the urethane foam had been adhered were cut out, and the adhesion between the urethane foam and the sheet was measured. on the other hand,
Another sheet (not bonded with urethane) that had been vacuum formed in the same manner as above was partially cut out, and the ash adhesion on the surface of the sheet was examined. The results are shown in Table 1. Adhesion: After separating the urethane foam from the sample piece by hand, use a knife to touch the sheet with the remaining urethane.
After cutting into 100 squares, adhesive tape was pasted onto the squares, and when the adhesive tape was vigorously peeled off from the sheet, the residual urethane foam squares remaining on the sheet side were examined. Ash adhesion: × Adhesive even at a height of -5 cm or more △ Adhesive at a height of -3 to 5 cm ○ Adhesive or not at a height of -3 cm or less. Anti-blocking property: After overlapping the antistatic agent layer sides of two sheets,
At 20℃ and 60% relative humidity with a load of 50g/ ^cm2 .
The presence or absence of adhesion (blocking) of the sheet after being left for 24 hours was measured. Good (◯): No blocking. Fair (△): Some blocking is observed, but the sheet can be easily peeled off by hand. Poor (x)...Blocking is large. Examples 2 to 4, Comparative Example 1 In Example 1, the mixing ratio of the antistatic agent "Polymine SN" and "ST" to be applied was changed as shown in Table 1, and the surface gloss layer side was charged with A urethane foam/sheet laminated insulation material was obtained in the same manner except that no inhibitor was applied. This laminated heat insulating material was evaluated in the same manner as in Example 1.
The results are shown in Table 1. Example 5, Comparative Examples 2 to 7, Comparative Example 10 In Example 1, the types of antistatic agent applied to the glossy layer side of the sheet and the antistatic agent applied to the urethane adhesive surface of the sheet were as shown in Table 1. A urethane foam/sheet laminated insulation material was obtained in the same manner except for the following changes.

【table】

[Table] Examples 7 to 11 Laminated insulation sheets were prepared in the same manner as in Example 5, except that the composition of the antistatic agent (AS agent) applied to the back side of the sheet to be bonded to urethane was changed as follows. Obtained. The physical properties of this product are shown in Table 2.

[Table] * Component (A) Polymin P - BASF's polyethyleneimine Epomin P-1000 - Nippon Shokubai Kasei's polyethyleneimine Examples 12 to 15, Comparative Examples 8 to 9 Layered material obtained in Example 1 as a sheet for differential pressure molding A urethane foam/sheet laminated heat insulating material was obtained in the same manner as in Example 5, except that the sheets obtained in Examples 2 to 7 were used instead of the sheets. The physical properties of this product are shown in Table 3.

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention;
FIG. 2 is a sectional view of the sheet. In the figure, 1 is a stainless steel frame, 2 is a sheet for differential pressure molding (lining material), 2a is a coating agent layer, 2c is an adhesive layer, 3 is a cavity, 4' is a urethane foam,
5 is an injection port.

Claims (1)

[Scope of Claims] 1. A molded article of a carboxyl group-containing polyolefin resin and a urethane foam contain the following components (A) and (B).
Composite insulation adhesive composition for structures laminated with water-based adhesives containing: (A) a water-soluble adhesive selected from the group consisting of polyethyleneimine, poly(ethyleneimine-urea) and ethyleneimine adducts of polyamine polyamides; Polyimine compound 20-80% by weight (B) Nitrogen-containing cationic or amphoteric acrylic polymer 80-20% by weight. 2. The composite heat insulating material according to claim 1, wherein the carboxyl group-containing polyolefin resin is an ethylene/acrylic acid random copolymer or a maleic anhydride grafted polypropylene. 3. Component (B) is an amphoteric compound obtained by modifying the tertiary nitrogen atom of a polymer consisting of the following components (a) to (c) with an amphoteric agent, as set forth in claim 1. composite insulation 20-40% by weight 60-80% by weight (c) Other hydrophobic vinyl monomers 0-20% by weight [However, in each formula, R ¹ is H or CH ₃ , R ² and R ³ are each H or carbon number 1-2 an alkyl group, R ⁵ is an alkyl group having 1 to 18 carbon atoms,
A is an alkylene group having 2 to 6 carbon atoms].