JPS6151543B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive foam, and more particularly, it is used to adhere to and reinforce thin steel plates for vehicles, which are used to reduce the weight of vehicles, and to maintain vibration damping properties. The present invention relates to an adhesive foam suitable for.

2. Description of the Related Art In recent years, in order to reduce the weight of vehicles such as passenger cars, buses, and trucks, vehicle bodies have been formed of thin steel plates. However, when the vehicle body is made thinner, a problem arises in that the strength and vibration damping properties are reduced. Therefore, in order to maintain the strength and vibration damping properties of the vehicle body, it has been proposed to attach a rubber sheet, a resin foam sheet, an asphalt sheet, or a rubberized asphalt sheet to the thin steel plate that constitutes the vehicle body.

However, all of these sheets have poor adhesion to steel plates, and as a result, it has not been possible to sufficiently maintain the desired vehicle body strength and vibration damping properties.

Therefore, the inventors of the present invention have conducted extensive research in order to develop a material that has excellent adhesion to steel plates and the like that make up the vehicle body, and is capable of maintaining reinforcing effects and damping properties.

As a result, they discovered that an adhesive foam obtained by subjecting a polyurethane foam to a specific treatment with a compound containing a special modified prepolymer is suitable for the purpose, and has completed the present invention. . That is, the present invention provides (A) a modified product of a prepolymer consisting of a liquid rubber having at least two or more hydroxyl groups and a polyisocyanate compound with a compound having an acryloyl type double bond and a hydroxyl group, and (B) a crosslinking agent. On one side of a sheet or film of polyurethane foam impregnated with a formulation containing (A)
A liquid rubber having at least two or more hydroxyl groups in the molecule, a modified product of a prepolymer made of a polyisocyanate compound with a compound having an acryloyl double bond and a hydroxyl group, (B) a crosslinking agent, and (C) a tackifier. The present invention provides an adhesive foam coated with a formulation comprising:

There are no particular restrictions on the polyurethane foam sheet or film that serves as the base material of the adhesive foam of the present invention, and various types can be used.
The thickness of this sheet or film may be determined as appropriate depending on the thickness of the steel plate constituting the vehicle body, the degree of reinforcement, etc., but is usually 0.5 to 20 mm.

The formulation that is then impregnated into the polyurethane foam sheet or film essentially consists of (A) a modified version of a particular prepolymer and (B) a crosslinking agent. This modified prepolymer is produced by modifying a prepolymer obtained by reacting a polyisocyanate compound with a liquid rubber having at least two or more hydroxyl groups in the molecule, with a compound having an acryloyl type double bond and a hydroxyl group. It is something that will be done. Here, the liquid rubber having at least two or more hydroxyl groups in its molecule is fluid at room temperature, forms a three-dimensional network structure through an appropriate chemical treatment, for example, a curing treatment, and is made of ordinary vulcanized rubber. It is a polymer that exhibits exactly the same physical properties as . Examples of such liquid rubbers include polybutadiene, polyisoprene, polystyrene, polychloroprene, polyethylene, butadiene/isoprene copolymer, acrylonitrile/butadiene copolymer, and polybutadiene having an average molecular weight of 500 to 8,000 and having a hydroxyl group at the molecular end.
Examples include so-called telechelic liquid rubber such as styrene/butadiene copolymer, liquid urethane rubber, liquid thiokol, pyrolyzed rubber, ozonolyzed rubber, and liquid silicone rubber. There are various polyisocyanate compounds used to react with this liquid rubber to obtain a prepolymer, but preferred examples include tolylene diisocyanate and 4,4'-diphenylmethane diisocyanate. can. Various methods can be used to produce a prepolymer by reacting the liquid rubber with the polyisocyanate compound, and there are no particular limitations. For example, liquid polybutadiene having a hydroxyl group at the end is Since it is an exothermic reaction in which an equivalent amount of tolylene diisocyanate is gradually added and reacted while stirring, the temperature is adjusted to 60°C or less and the reaction is allowed to proceed for about 4 hours. The obtained prepolymer is further modified to obtain a modified product. Compounds having an acryloyl type double bond and a hydroxyl group used for this modification include, for example, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate,
Examples include 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate. The reaction between this compound and the prepolymer described above can be carried out under various conditions, but
For example, 2-hydroxyethyl acrylate is gradually added to the prepolymer with stirring so that NCO/OH=1.0. An organotin catalyst can also be used to accelerate the urethane reaction. When the reaction is carried out at 60° C. or lower for about 4 hours, a compound (P) represented by the structural formula shown below is obtained. Furthermore, a polymerization inhibitor such as hydroquinone may be added to improve stability during reaction and storage. As a method for synthesizing a modified prepolymer, in addition to the method described above, the reaction order may be changed as follows. That is, it is also possible to react a polyisocyanate compound with a compound having an acryloyl type double bond and a hydroxyl group, and then react the reaction product with a liquid rubber having a hydroxyl group at the end of the molecule.

The types of modified prepolymers obtained in this way vary depending on the type of liquid rubber, polyisocyanate compound, etc. used, but for example, liquid and rubber include polybutadiene and polyisocyanate compounds having two hydroxyl groups in the molecule. When tolylene diisocyanate is used as the compound, and 2-hydroxyethyl acrylate is used as the compound having an acryloyl double bond and a hydroxyl group, the molecular weight is approximately 3000, the viscosity is 40000 CPS/60°C, the color is light brown and transparent, and the structural formula is A compound represented by is obtained. The modified prepolymer represented by this structural formula has the trade name:
It is known as Poly bd R-45ACR (sold by Idemitsu Petrochemical Co., Ltd.).

On the other hand, the crosslinking agent used in the present invention has the effect of reacting with each molecule of the modified prepolymer, especially the double bond portion, crosslinking each molecule, and hardening the modified product into a three-dimensional network structure. It shows
Generally, various peroxides are preferably used. Specifically, benzoyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, di-t-butyl peroxide, t-butyl perbenzoate, bis-(4-t-butylcyclohexyl) peroxydicarbonate, etc. I can do it.

As mentioned above, the composition used in the present invention basically consists of (A) a modified prepolymer and (B) a crosslinking agent, but may further contain neopentyl glycol diacrylate and tritriacrylate as necessary. A crosslinking agent such as allyl cyanurate, trimethylolpropane trimethacrylate, divinylbenzene, α-methylstyrene, vinyltoluene, or styrene may be appropriately added to facilitate the crosslinking reaction of the modified prepolymer. Furthermore, if desired, organic metal compounds such as cobalt naphthenate or amines may be used as reaction accelerators, hindered amine compounds, hindered phenol compounds, triazole compounds, etc. may be used as anti-aging agents, and metal oxides, metal carbonates, metals may be used as fillers. Sulfates, etc., and solvents such as toluene, xylene, industrial solvent naphtha, and kerosene can be blended. In addition, colorants can also be added.

The proportions of each component in this compound vary depending on various conditions and cannot be unambiguously determined, but usually 0.1 to 10 parts by weight of crosslinking agent and 0.1 to 10 parts by weight of crosslinking agent and 0.1 to 10 parts by weight of crosslinking agent and 100 parts by weight of modified prepolymer. The amount of the agent is preferably 0 to 400 parts by weight.

In the present invention, the above-mentioned polyurethane foam sheet or film is impregnated with the above-mentioned composition, but as a matter of course, the composition must have fluidity during impregnation. Therefore, when this formulation is impregnated into a polyurethane foam sheet or film, the modified prepolymer in this formulation is in an uncrosslinked state.

In the present invention, the formulation is applied to one side of a polyurethane foam sheet or film impregnated with the formulation described above. This formulation is the above formulation plus a tackifier, that is, the essential components are (A) a modified prepolymer, (B) a crosslinking agent, and (C) a tackifier. Here, the modified prepolymer and the crosslinking agent are basically the same as those in the formulation described above, but the tackifying agent is terpene resin, rosin, coumaron, etc.
Indene resin, terpene phenol, aromatic petroleum resin, aliphatic petroleum resin, etc. are used. This formulation, like the formulations described above, must have flow properties when applied to one side of a formulation-impregnated polyurethane foam sheet or film. That is, upon application, the modified prepolymer in the formulation is in an uncrosslinked state. The proportion of each component in this compound varies depending on various conditions such as the desired adhesive strength, and cannot be unambiguously determined, but usually the proportion of the crosslinking agent is 100 parts by weight of the modified prepolymer. It should be blended in a proportion of 0.1 to 10 parts by weight and 20 to 100 parts by weight of the tackifier. Moreover, a crosslinking aid can be added to this blend as appropriate, similarly to the blend.

The adhesive foam of the present invention obtained by applying the formulation to one side of a polyurethane foam sheet or film impregnated with the formulation as described above has a highly adhesive surface. If this adhesive foam is attached to a so-called white body, which is obtained by press-molding a thin steel plate, and then cured and bonded under baking conditions, the adhesive foam can be attached to the car body made of thin steel plate. The adhesive foam is bonded and integrated with extremely strong handling force. As a result, the weight of the car body can be reduced by thinning the steel plate, while at the same time
It is possible to increase the mechanical strength of the vehicle body and improve vibration damping properties.

As mentioned above, when adhering the adhesive foam of the invention to a body-in-white, processing under baking conditions results in the formation of a compound impregnated into a sheet or film of polyurethane foam and a compound applied on one side. The modified prepolymer present in both formulations and the crosslinking agent react to crosslink and cure. As a result, the strength of the foam itself is increased by the impregnated compound, and at the same time, the adhesion between the foam and the white body is enhanced by the applied compound.

Therefore, the adhesive foam of the present invention can be effectively used as a reinforcing material for the bodies of various vehicles.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 A modified prepolymer represented by the above structural formula (P) (molecular weight approximately 3000, viscosity 40000 CPS/60°C,
Weigh out 100 g of light brown transparent product (Product name: Poly bd R-45ACR, sold by Idemitsu Petrochemical Co., Ltd.) into a separable flask, add 72 g of styrene monomer,
16 g of trimethylolpropane methacrylate and 4 g of dicumyl peroxide were added and thoroughly stirred at room temperature to obtain a blend. A compound was also obtained by adding 20 g of coumaron-indene resin to the same compound. Next, apply the compound to a thickness of 3 mm and a width of 30 mm.
A tacky foam was obtained by impregnating a polyurethane foam sheet (density 0.05 g/cm ³ ) with a length of 350 mm and applying the formulation on one side of the foam sheet. A sample for vibration damping measurement was prepared by attaching the adhesive side of this foam to a 1 mm thick steel plate and curing it at 120°C for 45 minutes. Subsequently, using this sample, the loss coefficient was measured by the resonance method.
As a result, the loss coefficient was 0.26 under the conditions of a frequency of 100 Hz and a measurement temperature of 20°C.

Comparative Example 1 As a sample for vibration damping measurement, a 3 mm thick sample, which is commercially available as a damping material for the floor of a passenger car, was used.
The loss coefficient was measured using an asphalt sheet attached to a 1 mm thick steel plate under the same conditions as in Example 1, and found to be 0.18.

Claims (1)

[Claims] 1 (A) A modified product of a prepolymer consisting of a liquid rubber having at least two or more hydroxyl groups and a polyisocyanate compound with a compound having an acryloyl type double bond and a hydroxyl group, and (B)
On one side of a polyurethane foam sheet or film impregnated with a compound containing a crosslinking agent, (A) an acryloyl type double bond of a prepolymer consisting of a liquid rubber having at least two or more hydroxyl groups in the molecule and a polyisocyanate compound; and a modified product with a compound having a hydroxyl group, (B) a crosslinking agent, and (C) a tackifier.