JP2575478B2 - Method for producing urethane foam composite material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a urethane foam composite material, particularly a composite material for an automobile interior, for example, a substrate such as a molded ceiling, a door panel, and a rear tray (hereinafter abbreviated as a core material). And a method for producing the same.

[Conventional technology]

Conventionally, core materials used for automotive interior composite materials, especially molded ceilings, are made by mixing lint and phenolic resin and heat-molding, resin felt, melamine resin impregnated and heat-molded, corrugated cardboard, glass mat molded articles, A molded core material such as a polystyrene board is used. In practice, vinyl leather, cloth or the like having a cushion layer is further adhered to the core material to form a molded ceiling.

[Problems to be solved by the invention]

However, these core materials have problems such as weight, odor, rigidity, heat resistance, generation of fine powder, and dimensional stability. Recently, the demand for the development of lightweight core materials with excellent rigidity, heat resistance, and dimensional stability has increased as energy savings in automobiles have increased, and the development of composite core materials using lightweight urethane foam as the core material has been increasing. There has been proposed a method in which urethane foam is used as a core material, and a glass mat, a nonwoven fabric, or the like is used as a reinforcing material, and the resulting material is heated and pressed.

As a bonding method of the core material and the reinforcing material, a method of impregnating a urethane prepolymer into a urethane foam and utilizing a reaction with moisture to heat-mold, a thermosetting resin, for example, epoxy, melamine, phenol-based, etc. A method using an adhesive and a method of imparting a function as a part of a reinforcing agent by combining an aqueous emulsion with bonding between laminations have been studied.

When a composite material is formed using such an adhesive, the method using a urethane prepolymer makes it difficult to eliminate unevenness in penetration of the core material into the urethane foam.
Variations in hardness and the like become problems, and there are problems such as a slow curing time.

In addition, when a thermosetting resin is used, there are problems such as odor, flexibility, sound absorption, and soundproofing.

Furthermore, in the method using an aqueous emulsion that is excellent in handling, an emulsion having an adhesive function is generally mainly made of a thermoplastic resin, so that rigidity, heat resistance, moisture resistance, water resistance,
Furthermore, dimensional stability and the like become a problem, and they have not been put to practical use.

As a urethane foam composite material adhesive which solves this problem, Japanese Patent Application No. 62-257081 proposes a production method using an epoxy-modified acrylic emulsion and an amine-based curing agent in combination.

However, in this method, in a method in which pressing is performed at a high temperature for a long time as a pressing condition, sufficient adhesive properties can be obtained, but if the hot pressing time is shortened for the purpose of improving productivity, curing is weak. Insufficient adhesive properties such as adhesive strength, rigidity, heat resistance, moisture resistance, water resistance, dimensional stability, etc. were lacking in practicability, and forced to shorten the hot press time.

[Means for solving the problem]

The present inventors have conducted intensive studies to solve these problems, and as a result, they have found that the use of a mixture of an aqueous emulsion and a formaldehyde condensed resin is extremely effective in shortening the hot press time. As a result, the present invention has been completed.

That is, the present invention relates to a method in which a urethane foam is used as a core material, an adhesive is applied to both surfaces thereof, and a glass mat and a nonwoven fabric are laminated as a reinforcing material so as to sandwich the urethane foam, and are composited by hot pressing. And a method for producing a urethane foam composite material, wherein a mixture of an aqueous emulsion and a formaldehyde condensation resin is used as an adhesive.

In the present invention, the urethane foam for the core material used in the urethane foam composite material is a foam sheet obtained by slicing a hard or semi-rigid foam having an expansion ratio of 10 to 40 times to a thickness of 3 to 10 mm.

Further, the glass mat, glass fiber woven into reticulated as the nonwoven fabric is of the order of basis weight 100 g / m ^2, the nonwoven fabric A, nylon, polyester, such as rayon, basis weight 50 g / m ² of about It is a non-woven fabric.

The aqueous emulsion used in the present invention is an acrylic emulsion, an ethylene-vinyl acetate copolymer emulsion,
Alternatively, the emulsion is a mixture of the above two emulsions, and has a glass transition temperature (Tg ° C) of -5 to 50 ° C.

Among these emulsions, the acrylic emulsion is a copolymer emulsion of a hard monomer, a soft monomer, and a functional group monomer described below.

Specifically, examples of the hard monomer include one or more of styrene, methyl acrylate, acrylonitrile, and vinyl acetate.

Examples of the soft monomer include one or more of methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate.

As the functional group monomer, those having a carboxyl group include acrylic acid, methacrylic acid, itaconic acid,
Maleic acid, fumaric acid and the like, and acrylamide, methacrylamide, and maleamide as those having an amide group, and those having a hydroxyl group, such as hydroxyethyl acrylate, hydroxyethyl methacrylate,
Hydroxypropyl acrylate and the like, and those having N-methylolamide and the like include N-methylolacrylamide and the like.

The glass transition temperature (Tg ° C.) of the copolymer emulsion of the above monomers is an acrylic emulsion in the range of −5 to + 50 ° C. The preferred composition ratio of these is 40 to 70 parts by weight as a hard monomer, 25-55 as monomer
Parts by weight, and 1 to 10 parts by weight as a functional group monomer. However, the total of these three is 100 parts by weight.

More preferred combinations and composition ratios are styrene,
Or 40 to 70 parts by weight of methyl methacrylate, 25 to 55 parts by weight of butyl acrylate, 1 to 3 parts by weight of each of hydroxyethyl acrylate, methacrylic acid and acrylamide, and a copolymerized solid content of 45 to 50%, pH
It is an emulsion with a viscosity of 7-9 and a viscosity of 100-5,000 cps.

Glass transition temperature of the above acrylic emulsion (Tg ° C)
However, when the temperature is −5 ° C. or less, rigidity, heat resistance and the like are lacking, and when the temperature is 50 ° C. or more, adhesion to urethane foam, glass mat and nonwoven fabric is reduced, and adhesion becomes a problem.

The ethylene-vinyl acetate copolymer emulsion has an ethylene content of 10 to 30 parts by weight, a solid content of 45 to 65%, and a pH of 4
6, viscosity is 100 ~ 10,000cps, glass transition temperature is -2 ~
+ 15 ° C emulsions.

The emulsion is already on the market, and preferably has a glass transition temperature (Tg ° C) of 0 ° C or higher. Further, a mixture of an acrylic emulsion and an ethylene-vinyl acetate copolymer emulsion is obtained by blending the above two emulsions in an arbitrary ratio. From the viewpoint of rigidity, heat resistance, dimensional stability, and the like, the mixing ratio of the acrylic emulsion is preferably 50 parts by weight or more as a solid content.

Polyethylene glycol alkyl phenyl ether nonionic surfactant used in the present invention, Indicated, the ethylene oxide chain length is long, 30 mol or more polymerized, HLB is 18-20, active ingredient 50-1
A transparent liquid in which the active ingredient is 60% is preferable in terms of imparting miscibility with the aqueous emulsion and providing viscosity stability of the formaldehyde condensed resin composition.

The nonionic surfactant is preferably blended in an amount of 0.5 to 5 parts by weight (apparent) with respect to 100 parts by weight of the solid content of the aqueous emulsion.

When the nonionic surfactant is less than 0.5 parts by weight,
Viscosity stability when compounding a formaldehyde condensed resin, that is, the viscosity greatly increases with time, and in the worst case, gelation occurs within several hours, which is not preferable because of lack of practicality.

If the amount of the nonionic surfactant is more than 5 parts by weight, the foaming property, water resistance and moisture resistance of the composition are undesirably reduced.

When using the above nonionic surfactant, use water
It is convenient to use an aqueous solution dissolved in 20 to 30% [apparent concentration (assuming the solid content is 100%)].

Formaldehyde condensation resin used in the present invention, for example, urea resin, melamine resin, urea-melamine co-condensation resin, resorcinol resin, phenolic resin, ketone resin and the like, so-called water-soluble initial condensate with formalin, and these Emulsion type polymers are mentioned. Of these, urea resin is preferred from the viewpoint of shortening the hot press time, viscosity stability when blending with the aqueous emulsion, hue, price, etc., the molar ratio of formaldehyde to urea is 1.4 to 1.7, and the free formaldehyde concentration is 0.3 to 1.5%, solid content 45-65
%, A urea resin having a viscosity in the range of 10 to 500 cps.

When the molar ratio is 1.4 or less and the free formaldehyde concentration is 0.3% or less, short-time adhesion by hot pressing is lacking. When the molar ratio is 1.7 and the free formaldehyde concentration is 1.5% or more, the work is performed. The odor at the time is remarkable, which is an environmental health problem.

The mixing ratio of the aqueous emulsion and the formaldehyde condensation resin of the present invention is in the range of 5 to 50 parts by weight of the formaldehyde condensation resin with respect to 100 parts by weight of the solid content of the aqueous emulsion.

When the amount of the formaldehyde condensed resin is less than 5 parts by weight, short-time adhesiveness is lacking, and the adhesiveness, rigidity, and other adhesive properties are not satisfied. When the amount is more than 50 parts by weight, the adhesion between the urethane foam and the reinforcing agent is reduced. In addition to the fact that sufficient adhesive properties cannot be obtained, a problem of odor occurs and the practicality is lacking.

The production of a urethane foam composite material using an adhesive in which the aqueous emulsion of the present invention and a formaldehyde condensation resin are blended is carried out by a usual coating method and a bonding method.

For example, an adhesive is uniformly applied to both surfaces of a urethane foam with a roll coater or a spray device, and a urethane foam is used as a core material, a glass mat and a nonwoven fabric are sandwiched from both sides in this order, and heated to 120 to 150 ° C. It can be obtained by hot pressing for 30 to 60 seconds with a die press.

In the production of the urethane foam composite material of the present invention, a blend of the aqueous emulsion and the urea resin may be added, if necessary, to a curing accelerator such as ammonium chloride, a free formaldehyde catcher agent such as granular urea, a coloring agent, and an additive. A tackifier, an antioxidant, a release agent and the like may be used in combination.

As described above, in the production of the urethane foam composite material of the present invention, the use of a blend of an aqueous emulsion and a formaldehyde condensed resin reduces the hot pressing time, rigidity, heat resistance, water resistance, moisture resistance, and dimensional stability. The formaldehyde condensation resin which is a thermosetting resin contributes remarkably, the aqueous emulsion contributes to adhesive strength and flexibility, and the above-mentioned physical properties to be provided as a urethane foam composite material are fully satisfied. Thus, the practical value of the method for producing a urethane foam composite material is extremely high.

〔Example〕

Next, the present invention will be specifically described with reference to Production Examples, Examples, and Comparative Examples, but is not limited thereto.

In the following, parts or percentages are by weight unless otherwise specified.

Production Examples 1 to 4 An acrylic emulsion as an aqueous emulsion used in the present invention was prepared by mixing 100 parts of a monomer composition shown in Table 1, 0.5 part of sodium dodecylbenzenesulfonate, and 50 parts of distilled water.
The mixture was stirred in advance to obtain a monomer emulsion.

Separately, 50 parts of distilled water and 0.2 parts of sodium dodecylbenzenesulfonate were charged in a flask, the temperature was raised to 70 ° C. while stirring under a nitrogen blanket, and 0.5 part of potassium persulfate was administered. Was continuously administered over 4 hours, and the remaining monomers were polymerized at the same temperature for 4 hours to complete the polymerization. Then cooled to 30 ° C or less, 14
The pH was adjusted to 7 to 9 with aqueous ammonia, and an aqueous solution of partially saponified polyvinyl alcohol was added to obtain an acrylic emulsion having a viscosity of 3000 cps and a solid content of 50%.

Example 1 To 100 parts of the acrylic emulsion obtained in Production Example 1, 5 parts of a 20% emulgit 25 aqueous solution (manufactured by Daiichi Kogyo Kagaku KK) as a polyethylene glycol alkylphenyl ether-based nonionic surfactant, and a formaldehyde condensation resin (Trade name: Structbond C-3, manufactured by Mitsui Toatsu Chemicals KK, solid content 65%, viscosity 500 cps, pH 7.0, formaldehyde / urea molar ratio = 1.4, free formalin concentration
(0.6%) 23 parts were mixed to obtain an adhesive for urethane foam composite material. Apply this adhesive to both sides of semi-rigid urethane foam (expansion ratio 20 times, thickness 7 mm) using air spray.
200 g / m ² and uniform coating, a glass mat, the order of nonwoven Kutsugaese urethane foam sandwich form, crimped 30 seconds at a pressure of 0.1 kg / cm ² at 0.99 ° C. hot press, to obtain a urethane foam composite .

Physical properties were tested by the following methods.
It was shown to.

Test method a) Short-time adhesiveness Under the hot pressing conditions of the urethane foam composite material of the example, the bonding state and rigidity at a high temperature immediately after being taken out of the press were observed with a finger and indicated as follows.

○ ・ ・ ・ Good adhesion state and rigidity △ ・ ・ ・ Adhesion state and rigidity insufficient × ・ ・ ・ No rigidity and easy peeling between layers b) Odor Sensation of odor during hot pressing and immediately after opening It was determined and displayed as follows.

○ ・ ・ ・ Slight odor at opening pressure △ ・ ・ ・ Large odor at opening pressure (however, small during hot pressing) × ・ ・ ・ Large odor and irritation to eyes c) Pot life Adhesive compound Was allowed to stand at room temperature for 24 hours, and the change in viscosity was measured using a BM-type rotational viscometer, and displayed as follows.

○ ・ ・ ・ Viscosity change rate of 50% or less △ ・ ・ ・ Viscosity change rate of 50 to 200% × ・ ・ ・ Viscosity change rate of 200% or more or gelation d) Adhesive strength The urethane foam composite material obtained in the example was used. After being cut to a width of 25 mm and left at room temperature for 24 hours, a 180 ° peel strength was measured by Intesco.

E) Using a Fujii-type tensile tester, a 70 × 200 mm rigid composite
A load is applied at a speed of 50 mm / min with a span length of 100 mm,
The breaking strength was measured, the bending strength was calculated by the following equation, and displayed as rigidity.

Bending strength (rigidity) calculation method S: width of sample (cm) T: thickness of sample (cm) W: maximum load (at break) (kg) L: length of span (cm) F) hardness Kamishima Seisakusho It was measured using a Shore hardness tester, type D manufactured by K.K.

G) Heat resistance The sample obtained in d) was measured in a 100 ° C atmosphere by the same test method as in d).

G) Water resistance The sample obtained in d) was immersed in water at 20 ± 2 ° C for 30 minutes and measured by the same test method as in d).

D) Moisture resistance The sample obtained in d) was subjected to 168 under constant temperature and humidity of 50 ± 2 ℃ / 95% RH.
After the time treatment, it was measured by the same test method as in d).

D) Dimensional stability The composite material is precisely cut into a 100 x 100 mm square, and left for 168 hours under the conditions of the heat resistance of (i) and the humidity resistance of (i) above, and the length changed at room temperature is measured. Displayed as

・ ・ ・: Change of 1 mm or less △: Change of 1 to 3 mm ×: Change of 3 mm or more Example 2 Example except that the structuring bond C-3 used in Example 1 was changed to 7 parts. According to No. 1, a urethane foam composite material was prepared and subjected to a test, and the results are shown in Table 2.

Example 3 A urethane foam composite material was prepared and subjected to a test in accordance with Example 1, except that the amount of the structuring bond C-3 used in Example 1 was changed to 32 parts. The results are shown in Table-2. .

Example 4 A urethane foam composite material was subjected to a test after preparation according to Example 1, except that the acrylic emulsion used in Example 1 was changed in Production Example 2, and the results are shown in Table 2.

Example 5 A urethane foam composite material was prepared and subjected to a test in accordance with Example 1, except that the acrylic emulsion used in Example 1 was changed to Production Example 3, and the results are shown in Table 2.

Example 6 A urethane foam composite material was prepared and subjected to a test according to Example 1, except that the acrylic emulsion used in Example 1 was changed to Production Example 4, and the results are shown in Table 2.

Example 7 A urethane foam composite material was prepared and subjected to a test in accordance with Example 1, except that the 20% emulgit 25 aqueous solution used in Example 1 was changed to 1.5 parts, and the results are shown in Table 2.

Example 8 A urethane foam composite material was prepared and subjected to a test in accordance with Example 1, except that the 20% emulgit 25 aqueous solution used in Example 1 was changed to 12 parts, and the results are shown in Table 2.

Example 9 The acrylic emulsion used in Example 1 was replaced with an ethylene-vinyl acetate copolymer emulsion (trade name: Denka EVA Latex 25, manufactured by Denki Kagaku Kogyo KK, solid content 50%, pH 5.0,
A urethane foam composite material was prepared and subjected to a test according to Example 1, except that the viscosity was changed to 1000 cps and the glass transition temperature (Tg + 15 ° C.), and the results are shown in Table-2.

Example 10 The acrylic emulsion used in Example 1 was replaced with an ethylene-vinyl acetate copolymer emulsion (trade name: Denka EVA Latex 30, manufactured by Denki Kagaku Kogyo KK, solid content 55%, pH 5.0,
Except that the viscosity was changed to 2500 cps and the glass transition temperature (Tg0 ° C.), a urethane foam composite material was subjected to a test after preparation according to Example 1, and the results are shown in Table-2.

Example 11 The adhesive composition obtained in Example 1 and the adhesive composition obtained in Example 7 were blended at a ratio of 7: 3.
The urethane foam composite material was subjected to a test after preparation, and the results are shown in Table-2.

Example 12 The adhesive composition obtained in Example 2 and the adhesive composition obtained in Example 8 were blended at a ratio of 7: 3.
The urethane foam composite material was subjected to a test after preparation, and the results are shown in Table-2.

Example 13 The adhesive composition obtained in Example 3 and the adhesive composition obtained in Example 8 were blended in a ratio of 7: 3.
The urethane foam composite material was subjected to a test after preparation, and the results are shown in Table-2.

Comparative Example 1 A urethane foam composite material was prepared and subjected to a test in accordance with Example 1, except that the struct bond C-3 used in Example 1 was changed to 1 part, and the results are shown in Table-2. .

Comparative Example 2 A urethane foam composite material was prepared and subjected to a test in accordance with Example 1, except that the amount of the struct bond C-3 used in Example 1 was changed to 40 parts, and the results are shown in Table 2. .

Comparative Example 3 A urethane foam composite material was prepared and subjected to a test in accordance with Example 1, except that the 20% emulgit 25 aqueous solution used in Example 1 was changed to 1 part. The results are shown in Table 2.

Comparative Example 4 A urethane foam composite material was prepared and subjected to a test in the same manner as in Example 1 except that the 20% emulgit 25 aqueous solution used in Example 1 was changed to 15 parts, and the results are shown in Table 2.

Comparative Example 5 The formaldehyde condensed resin used in Example 1 was prepared using Euroid UF (manufactured by Mitsui Toatsu Chemicals KK, solid content 48%, viscosity 50c).
ps, pH 7.0, formaldehyde / urea molar ratio = 1.8, free formalin concentration 1.8%), and subjected to a test after preparing a urethane foam composite material according to Example 1,
The results are shown in Table-2.

Comparative Example 6 The formaldehyde condensed resin used in Example 1 was prepared using Euroid 305 (manufactured by Mitsui Toatsu Chemicals KK, solid content 58%, viscosity 40).
cps, pH 7.0, formaldehyde / urea molar ratio = 1.3, free formalin concentration 0.4%), except that the urethane foam composite material was prepared and subjected to a test according to Example 1.
The results are shown in Table-2.

[Effects of the Invention] As is apparent from Table 2, the method for producing a urethane foam composite material of the present invention has extremely low risk of environmental pollution and fire due to the use of an adhesive mainly composed of an aqueous emulsion. In addition, it can be applied sufficiently using a coating machine that is commonly used in the field of bonding, and the curing speed at the time of hot pressing, which was the biggest problem of the aqueous emulsion type adhesive, has been greatly improved. Not only is bonding possible,
Since it has excellent adhesive strength, hardness, rigidity, heat resistance, water resistance, moisture resistance, and dimensional stability to be provided as an automobile interior composite material, the practical value is extremely high and its significance is great.

Claims (5)

(57) [Claims] 1. A method in which a urethane foam is used as a core material, an adhesive is applied to both surfaces thereof, and a glass mat and a nonwoven fabric are laminated as a reinforcing material so as to sandwich the urethane foam, and a composite is formed by hot pressing. A method for producing a urethane foam composite material, comprising using a mixture of an aqueous emulsion and a formaldehyde condensation resin as an adhesive. 2. A blend of an aqueous emulsion and a formaldehyde condensed resin comprising 5 to 50 parts by weight of the formaldehyde condensed resin as a solid based on 100 parts by weight of the solids of the aqueous emulsion. 2. The method for producing the urethane foam composite material according to 1. 3. An aqueous emulsion having a glass transition temperature (Tg)
The method for producing a urethane foam composite material according to claim 1, which is an acrylic emulsion, an ethylene-vinyl acetate copolymer emulsion, or a mixture of the two types of emulsions, in the range of -5 to + 50 ° C. 4. The urethane foam composite material according to claim 1, wherein the aqueous emulsion contains 0.5 to 5 parts by weight of a polyethylene glycol alkyl phenyl ether nonionic surfactant based on 100 parts by weight of the solid content of the aqueous emulsion. Manufacturing method. 5. The method for producing a urethane foam composite material according to claim 1, wherein the formaldehyde condensation resin is a urea resin having a molar ratio of formalin to urea in the range of 1.4 to 1.7.