JPH0321543A - Molding - Google Patents

Abstract

PURPOSE:To make a lightweight molding with enhanced weatherability by putting a polyurethane layer on a foamed rubber, wherein the polyurethane is obtained by adding diamine of aromatic series to a specific urethane prepolymer followed by hardening, and by covering the resultant with a thermo- contracting tube. CONSTITUTION:A molding to be fitted to the body side of a car or its bumper is also equipped with damage preventing function against contact accident, etc., as well as decorativeness. This molding is formed by putting a specific polyurethane layer on a certain foaming substance and covering them with a termo-contracting tube. Examples of this foaming substance are rubber and resin. The specific polyurethane as mentioned is obtained by adding diamine of aromatic series to a urethane prepolymer as the product from reaction of polyole and polyisocyanate mixed in such a proportion that the molecular ratio of the isocyanate radical (-NCO) to the hydroxyl radical (-OH) will be no less than 2, that shall be followed by hardening process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a molding (hereinafter referred to as a molding) that is attached to the side surface or bumper of an automobile body, for example.

[Prior Art] Conventionally, moldings made of synthetic resin, mainly vinyl chloride resin, have been attached to the bodies and bumpers of automobiles. These moldings are attached to the sides and front and back of the car body, and have the function of preventing scratches caused by contact with other objects when opening a door, etc., as well as being decorative. [Problems to be Solved by the Invention] However, this molding made of vinyl chloride resin has a problem in that it is not an appropriate material for the purpose of weight reduction because the specific gravity of the vinyl chloride resin is as high as about 1.35. was there.

An object of the present invention is to provide a molding that is lightweight and has excellent weather resistance.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, a polyol and a polyisocyanate are added to a rubber or resin foam with an isocyanate group (-NCO)/hydroxyl group (-OH).
A method was adopted in which a polyurethane obtained by reacting the urethane prepolymer in an amount such that the molar ratio of are doing.

[Detailed explanation of the means] First, the rubber or resin foam will be explained. As the rubber foam, foams such as ethylene-propylene diene copolymer rubber (EPDM), ethylene-propylene copolymer rubber (EPM), and natural rubber (NR) can be used. Polyethylene (
PR), polypropylene (PP), polystyrene (PS)
Foams such as t) can be used. The foaming ratio is usually several times higher, but it can be set as appropriate depending on the purpose, such as weight reduction. Moreover, its specific gravity is 0.4-0. It is preferable that it is about 6.

Next, polyurethane will be explained.

As the polyol, polyether polyol and/or polyester polyol can be used.

As the polyether polyol, polyoxypropylene glycol, polyoxyethylene glycol, polytetramethylene oxide glycol, propylene oxide adduct of glycerin, propylene oxide adduct of trimethylolpropane, propylene oxide adduct of pentaerythritol, etc. are used. be able to.

Polyester polyols include ethylene glycol, propylene glycol, 1,4-butanediol, 1
．． One or more diols such as 3-butanediol, 2,3butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol and amber It is possible to use polyester polyols which are synthesized by reaction with one or more carboxylic acids such as adipic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid and the like.

As the polyisocyanate, 2.4-1-lylene diisocyanate. Tolylene diisocyanate, 65/35 (ratio of 2.4-tolylene diisocyanate and 2.6-1-lylene diisocyanate, the same shall apply hereinafter), 80/20 tolylene diisocyanate, 4.4'-diphenyl Methane diisocyanate, dianisidine diisocyanate, tridene diisocyanate, hexamethylene diisocyanate, metaxylene diisocyanate,
1,5-naphthalene diisocyanate, hydrogenated 4,4' diphenylmethane diisocyanate, hydrogenated xylene diisocyanate, hydrogenated 2,4-tolylene diisocyanate,
Hydrogenated 6 5/3 5 } Hydrogenated lylene diisocyanate, Hydrogenated 80/20 tolylene diisocyanate, Isophorone diisocyanate, 4,4'4" triphenylmethane triisocyanate, Tris (P-isocyanate phenyl)
Thiophosphate and the like can be used.

The ratio of the isocyanate group in the polyisocyanate to the hydroxyl group in the polyol is such that the molar ratio of isocyanate group (-NCO)/hydroxyl group (-OH) is 2 or more, preferably about 2 to 3.5. It is. 2
If the molecular weight is less than 1, the polyol and polyisocyanate react in a chain manner, resulting in an increase in molecular weight and loss of fluidity, which poses a problem when shaping the mold. This polyol and polyisocyanate are mixed in this ratio and reacted by heating at 80° C. for 3 hours in dry nitrogen gas to form a urethane prepolymer having isocyanate groups.

The aromatic diamine is a curing agent for the above-mentioned urethane prepolymer, and includes 4,4'-diphenylmethane-10-dichloroaniline, 4,4'-diphenylmethane, p
-phenylenediamine, ■. 5-naphthalenediamine,
One or more of 4.4'-diphenyl ether diane, 2.4-}lylene diane, 2.6-}lylene diane, etc. can be used. The amount of aromatic diamine used is preferably the amount necessary to cure the urethane prepolymer, that is, approximately equivalent to the isocyanate group contained in the urethane prepolymer. This aromatic di-based group is blended into the urethane prepolymer in an amount approximately equivalent to the isocyanate group in the urethane prepolymer, and heated if necessary, thereby converting the isocyanate group and the aromatic di-based group into ξ. The group reacts with the polyurethane and the polyurethane becomes active.

Next, heat shrink tube is a thin tube that shrinks when heated, and its material is polyvinyl chloride (PVV).
C), polyethylene terephthalate (PET), ethylene-i[vinyl copolymer (EVA), etc.]. The thickness of the heat shrinkable tube is preferably about 100 to 500 μm.

The heating conditions for shrinking the heat-shrinkable tube are appropriately set according to a conventional method, and are, for example, 120 to 200° C. for several tens of seconds.

In the mold of the present invention, for example, a foam made of rubber or resin is placed as an insert in the center of a mold that matches the shape of the mold, and a liquid mixture of the urethane brebolymer and aromatic diamine is applied to the outer periphery of the foam. It is manufactured by pouring and heating, covering the resulting precept with a heat shrink tube, and heating.

[Function] By employing the above means, a foam made of rubber or resin is used as an insert, and the urethane prepolymer having an isocyanate group and the aromatic diabase react with each other due to the reaction between the polyol and the polyisocyanate. By laminating polyurethane, covering it with a heat shrink tube and heating it, a molding that is lightweight and has excellent weather resistance can be obtained. [Examples 1 to 10 and Comparative Examples 1 to 4] Next, examples embodying the present invention will be described in comparison with comparative examples. In addition, in each of the following Examples and Comparative Examples, parts by weight are simply expressed as parts.

(1) Manufacture of molding First, an insert made of rubber or resin foam is placed in the center of a cylindrical mold with a bottom that matches the shape of the intended molding. On the other hand, a urethane polyol obtained by reacting a polyether polyol or a polyether polyol with a polyisocyanate was heated to 60° C. and defoamed under vacuum. A heated aromatic diamine was blended into this urethane prepolymer and defoaming was performed again to obtain a liquid mixture. Next, this liquid mixture was poured into the outer periphery of the insert, the insert was covered with a lid, and the insert was left to stand at 60° C. for 30 minutes to perform a ritual. At this time, the volume ratio of the polyurethane/insert was set to 60/40. Next, a heat shrink tube with a thickness of 300 μm was coated around the outer periphery of this precept-shaped article, and 12
A mold was manufactured by heating at 0 to 200°C for 20 seconds.

Table 1 shows the composition of polyurethane used in each example and comparative example. Further, the type of polyurethane used to manufacture the molding, the type of rubber or resin foam used as the insert, the specific gravity, and the type of heat shrinkable tube are shown in Table 2 below.

Table-1 The abbreviations in Table-1 represent the following meanings.

PPGIOOO: Polyoxypropylene glycol with an average molecular weight of 1000 PPG2000: Polyoxypropylene glycol with an average molecular weight of 2000 PPG3000: Polyoxypropylene glycol with an average molecular weight of 3000 TGIOOO: Triethylene glycol with an average molecular weight of 1000 PEAIOOO iPolyethylene adipate with an average molecular weight of 1000 PBA20 00: average molecule! 2000 polybutylene adipate PEBA3000: Polyethylene butylene adipate TDI having an average molecular weight of 3000: lylene diisocyanate XDI: Xylylene diisocyanate HMDI:
Hexamethylene diisocyanate oCA: 4,4'-
diphenylmethane 10-dichloroaniline p-po: p-phenylene diane DMDA: diphenylmethane diane DAD
:4.4'-diaminodiphenyl EG:ethylene glycol}10 :1,6 hexanediol The abbreviations in Table 2 have the following meanings.

Polyurethanes ``■'' to 0 indicate the polyurethanes in Table 1 above.

In Comparative Example 1, (11) indicates that no foam was used and the result was achieved using only vinyl chloride resin.

(2) Evaluation of physical properties Next, the shapeability and abrasion resistance of the molding obtained as described above were measured as follows.

Evaluation of formality: The appearance of the molding was visually judged.

○: The condition of the molding surface is good.

△: Slight stickiness remains on the molding surface.

×; Stickiness remains on the molding surface.

Evaluation of weather resistance: 5.
Weather resistance for 00 hours was evaluated.

○: No abnormality occurred in the mall.

Δ: Cracks occurred on the molding surface.

Table 3 As can be seen from Table 3 above, Examples 1 to 10 of the present invention
In all cases, no stickiness remained on the surface of the molding, the moldability was good, and no abnormality occurred in the molding even in a weather resistance test lasting 500 hours. Therefore, this molding is durable and can be used for a long period of time.

In addition, the specific gravity of the rubber or resin foam used as the insert is low at 0.50 to 0.63, and the specific gravity of polyurethane is also low at around 0.98, so the specific gravity of the entire molding obtained is lower than that of conventional vinyl chloride resin. The specific gravity was considerably smaller than 1.35, making it possible to reduce the weight.

On the other hand, when only vinyl chloride resin was used without using foam (Comparative Example 1), when diol was used as a hardening agent (Comparative Examples 2 and 3), and when heat shrink tube was not used (Comparative Example In the case of 4), weight reduction could not be achieved, stickiness remained on the surface, causing problems in shapeability, and cracks formed on the surface, causing problems in weather resistance.

As mentioned above, the reason why the molds of each example exhibit excellent performance is that they use a rubber or resin foam with a low specific gravity and polyurethane, and the polyurethane is made by using an excessive amount of polyisocyanate in advance to form isocyanate groups. This is thought to be due to the high molecular weight of the urethane prepolymer that has good reactivity with the isocyanate group and the use of an aromatic diamine with a benzene nucleus as the curing agent, so that the two reacted sufficiently. It will be done.

[Effects of the Invention] The molding of the present invention is sufficiently lightweight, and
It also has the effect of being excellent in weather resistance.

Claims (1)

[Claims] 1. Urethane prepolymer obtained by reacting polyol and polyisocyanate with a rubber or resin foam in an amount such that the molar ratio of isocyanate groups (-NCO)/hydroxyl groups (-OH) is 2 or more. A molding made by laminating polyurethane that has been cured by adding aromatic diamine to it, covering it with heat-shrinkable tube, and heating it.