JPS608931B2 - Molding method for semi-rigid urethane products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for molding semi-rigid urethane products, and more specifically, after spraying urethane paint onto the mold surface of a mold to form a coating edge, a core is formed inside the coating film. The present invention relates to a method of molding a semi-rigid urethane product by injecting a urethane polymer liquid to be formed (hereinafter referred to as a mold coating method).

Here, semi-rigid urethane products are defined as having a hardness of 20 to 9 degrees (
Examples of automobile interior parts include steering wheels, armrests, headrests, console boxes, change lever knobs,
Steering wheel pad, safety/gundo. Examples include assist grips, front and rear pillar trims, and instrument panel pads.

Many of the interior parts of automobiles are semi-rigid from the viewpoint of safety and feel, and most of them are molded from polyurethane resin from the viewpoint of physical properties and molding.

When this semi-rigid urethane product is molded by a mold coating method, the urethane polymer solution used to form the coating film is usually one whose main components are polyester polyol and diphenylmethane diisocyanate.

Since this diphenylmethane diisocyanate has yellowing, even if an antioxidant or ultraviolet absorber is added, yellowing cannot be sufficiently prevented, and after long-term actual vehicle driving, the product will discolor, crack, and deteriorate in wear resistance. There was a problem. In particular, as the interior parts of automobiles have become lighter in color in recent years, yellowing of the skin (paint film) of the product is noticeable and undesirable. In order to improve this yellowing, if the diisocyanate component of the urethane polymer liquid is a non-yellowing type such as hexamethylene diisocyanate or xylylene diisocyanate, discoloration and cracking of the coating film can be prevented. However, problems arose in terms of coating film strength and initial abrasion resistance.

In view of the above, the present invention provides a semi-hard urethane product that does not discolor or crack after long-term actual vehicle driving and has excellent coating strength and abrasion resistance. The purpose is to provide a molding method.

The gist of this invention is that isophorone diisocyanate is added stepwise to reacted saturated polyester polyol to which a chain extender has been added, and isophorone diisocyanate is further added stepwise to react. A pigment and a solvent are added to a one-component urethane polymer solution to prepare a urethane paint, and the urethane paint is sprayed onto the mold surface of the mold to form a coating film. A method for molding semi-rigid urethane products by injecting polymer liquid. The method of this invention will be explained in detail below.

First, add a saturated polyester polyol and a chain extender to
While mixing at 90 qo, isophorone diisocyanate is added stepwise and reacted for 2 to 4 hours, and isophorone diamine is added stepwise and reacted for 2 to 4 hours.

Thereafter, a solvent is added to adjust the viscosity and nonvolatile content of the polymer solution, and an ultraviolet absorber and an acidification inhibitor are added to prepare a one-component urethane polymer solution. Here, the saturated polyester polyols include 1,6-hexane adipate, butylene adipate, ethylene adipate,
Diethylene adipate and mixtures thereof may be mentioned.

The optimal molecular weight of this polyol is 800 to 2,200; if it is less than 800, the elongation of the coating will decrease, and if it is more than 2,200, the viscosity of the polymer liquid will increase, making spray coating difficult. As the chain extender, short chain diols having a molecular weight of 60 to 200 are preferred, such as ethylene glycol, diethylene glycol, propylene glycol, and dipropylene.

Examples include pyrene glycol, 1,4-butanediol, 1,5-bentanediol, 1,6-hexanediol, neobentyl glycol, and the like. The amount of this chain extender added is 0.5 to 2.0 per molar equivalent of the above polyol.
The molar equivalent is optimal; if it is less than 0.5 molar equivalent, the tensile strength and abrasion resistance of the coating film will decrease, and if it is more than 2.0 molar equivalent, the flexibility and elongation of the coating film will be reduced. The optimum amount of isophorone diisocyanate to be added is 2.5 to 4.0 molar equivalents per 1 molar equivalent of the polyol.
If the amount is less than 4.0 molar equivalent, the tensile strength of the coating will decrease or it will not become a polymer, and if it is more than 4.0 mol equivalent, the elongation and flexibility of the coating will decrease, and if it is severe, the polymer liquid will gel during the heating reaction. do.

The optimum amount of isophorone diamine to be added is 1.00 to 1.15 molar equivalents per 1 molar equivalent of the polyol, and if it is less than 1.00 molar equivalents, gelation or storage stability of the polymer solution may be poor. If the amount is more than 1.15 molar equivalent, the residual amine will cause discoloration of the coating film of the product.

Solvents include toluene, xylene, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK),
Inpropyl alcohol, dimethylformamide (DM
F), dioxane, etc. In addition, the ultraviolet absorber and antioxidant are each 0% relative to the nonvolatile content of the volima liquid.
．． The optimum content is 5 to 1%; below 0.5%, no effect is produced, and above 1%, a bleeding phenomenon occurs.

To the one-component urethane polymer solution prepared as above,
A suitable pigment and solvent are added to form a urethane paint, and this urethane paint is sprayed onto the mold surface of a mold that has been previously coated with a release agent and kept at a temperature of 30 to 6,000 ℃, and dried to a temperature of 5 to 80℃.
Forms the Buddha's painted waist.

A semi-rigid urethane product is obtained by injecting a urethane polymer liquid of integral skin treatment or water foaming treatment into the inside of this coating film using a reaction injection molding machine (BIM) or a low-pressure foaming machine and molding it. The semi-rigid urethane product thus obtained is
As shown in the examples below, even after long-term driving, no discoloration or cracks occur, and the coating has excellent properties in terms of hardness and abrasion resistance.

Note that this semi-rigid urethane product is applicable not only to automobile interior parts but also to other fields such as indoor furniture and toys.

Example 1 180 parts of 1,6-hexane adipate having a molecular weight of 1,000 and 1 $ part of neobentyl glycol were mixed and maintained at a molecular weight of 8,000, and 11 $ parts of isophorone diisocyanate was added dropwise into the mixture to conduct a pongee reaction. Then, 32 parts of isophoronediamine was further added dropwise to carry out a water reaction.

The temperature was kept at 80-90° during the reaction. After the reaction, 325 parts of toluene, 325 parts of inpropyl alcohol, 0.7 part of an antioxidant (Irganox 1010; manufactured by Ciba-Geigy) and an ultraviolet absorber (Tinuvin 32) were added.
8 (trade name, manufactured by Ciba Geigy) was added to obtain a one-component urethane polymer solution. This urethane polymer liquid 10
0 parts, 10 parts of pigment and parts of M old K40 were added and mixed to obtain a urethane paint. Apply 1 part of the above paint to the mold surface of a 50q0 mold.
After spraying to a thickness of 0 to 20 mm to form a urethane coating, RIM molding was performed to obtain a steering wheel with a hardness of 750 (C type).

Example 2 360 parts of butylene adibate with a molecular weight of 2000 and 1,6
- 21 parts of hexanediol were mixed and maintained at 80 qo.

A pongee reaction was carried out while adding 11 parts of isophorone diisocyanate, and then a further reaction was carried out while adding 32 parts of isophorone diamine. (Irganox 1010) and 0.5 parts of an ultraviolet absorber (Tinuvin 328) were added and mixed to obtain a one-component urethane polymer solution.To 100 parts of this polymer solution, 10 parts of pigment, 200 parts of MEK, and 20 parts of dioxane were added. After adding this to a urethane paint and spraying it on the mold surface of a 5000 mold to a thickness of 40 to 50 mm to form a urethane coating, low pressure molding (water foaming process) is performed to determine the hardness. A front pillar trim of 250 (C type) was obtained.Example 3 270 parts of ethylene butylene adibate with a molecular weight of 1500 and 32 parts of 1,4-butanediol were mixed,
Isophorone diisocyanate 1 was kept at 0qC.
The reaction was carried out for 4 hours while adding 5 parts of isophorone diamine, and then the pongee reaction was further carried out while adding 35 parts of isophorone diamine, and 350 parts of inpropyl alcohol, 20 parts of toluene, 300 parts of dioxane, and 0.0 parts of antioxidant were added. $ part (Irganox 1010), ultraviolet absorber 0. $ Department (Tinuvin 328)
were added and mixed to obtain a one-component urethane polymer solution.

To 10 parts of this polymer solution, 10 parts of pigment, 15 parts of toluene, and 150 parts of MEK were added to make a urethane paint.
This was spray-coated to a thickness of 50 to 60 mm on the mold surface of a 60 mm mold to form a urethane coating, and RIM molding (integral skin treatment) was performed to achieve a hardness of 50 mm (
C type) safety pad was obtained. Control example 1 360 parts of butylene adibate with a molecular weight of 2000 and 1,4
-16 parts of butanediol were mixed and kept at 80:00.

A water reaction was carried out while adding 134 parts of diphenylmethane diisocyanate, and then a further reaction was carried out while adding 37 parts of diphenylmethane diamine, and DMF3
A one-component urethane polymer solution was obtained by adding and mixing 5 parts of MEK, 350 parts of MEK, 0.8 parts of an antioxidant (Irganox 1010), and 0.8 parts of an ultraviolet absorber (Tinuvin 328). To 100 parts of this polymer liquid, 10 parts of pigment, 200 parts of M old K, and 20 parts of dioxane were added to make a urethane paint, and this was spray-painted on the mold surface of a 5000 mold to a thickness of 10 to 20 mm. , after forming the urethane coating film, RI
Performed M molding (integral skin treatment) and achieved a hardness of 75.
o (C type) steering wheel was obtained.

Control Example 2 180 parts of ethylene adipate having a molecular weight of 1000 and 11 parts of ethylene glycol were mixed and maintained at 80 oo.

The reaction was carried out for 4 hours while adding 10 parts of xylylene diisocyanate, and then the reaction was carried out for another 4 hours while adding 24 parts of xylylene diamine, followed by 325 parts of inpropyl alcohol, 325 parts of MEK, and 0.7 parts of antioxidant. (Irganox 1010), ultraviolet absorber 0.7 part (
Tinuvin (328 parts) was added and mixed to obtain a one-component urethane polymer solution. For 100 parts of this polymer solution, 1 part of pigment
0 part, M old K40 Ikarito was added to make a urethane paint, and this was spray-painted on the mold surface of a mold at 50℃ to a thickness of 40 to 50 mm to form a urethane coating film, and then low-pressure molding (water A front pillar trim with a hardness of 250 (C type) was obtained.

Control example 3 180 parts of butylene adibate with a molecular weight of 1000 and 1,4
-16 parts of butanediol were mixed and maintained at 80oC.

To this was added 9 parts of xamethylene diisocyanate and reacted for 4 hours, then added 32 parts of xamethylene diamine and reacted for another 4 hours, and then added 2 parts of toluene.
0 parts of ethyl acetate, 0.7 parts of an antioxidant (Irganox 1010), and 0.7 parts of an ultraviolet absorber (Tinuvin 328) were added and mixed to obtain a two-part urethane polymer main solution. For 10 bags of this base agent solution, an ethyl acetate solution (NCO 12%) prepared by reacting 3 moles of hexamethylene diisocyanate with 1 mole of trimethylolpropane was added.
Add 6 parts of as a hardening agent, 1 part of pigment, and part of M old K30, and spray paint this on the mold surface of a 5000 mold to a thickness of 50 to 60 mm to form a urethane coating. RIM
Molding (integral skin treatment) is performed to achieve a hardness of 50o.
(C type) safety pad was obtained. Table 1 shows the physical properties of the urethane paints used in Examples 1 to 3 and Control Examples 1 to 3.

Table 1 Using the urethane paint used in Examples 1 to 3 and Control Examples 1 to 3, the mold surface of a 100 m x 35 m x 5 test piece mold was coated with a film thickness of 20 mm, and then hand-painted. The mix "molded it.

Claims (1)

[Claims] 1. A pigment and a solvent are added to a one-component urethane polymer liquid to form a urethane paint, and the urethane paint is sprayed onto the mold surface of a mold to form a coating film, and then the inside of the coating film is In a method of molding a semi-rigid urethane product by injecting a urethane polymer liquid that forms the core, the one-component urethane polymer liquid is reacted by adding isophorone diisocyanate stepwise to a saturated polyester polyol to which a chain extender has been added. A method for molding a semi-rigid urethane product, characterized in that the main component is a product obtained by adding isophorone diamine in stages to the reacted product. 2. The one-component urethane polymer solution forming the coating film contains 0.5 to 2.0 molar equivalents of chain extender and 2.5 to 4.0 molar equivalents of isophorone diisocyanate per 1 molar equivalent of saturated polyester having a molecular weight of 800 to 2200. A patent characterized in that 1.0 to 1.15 molar equivalents of isophorone diamine are added and reacted by heating, and further, appropriate solvents, ultraviolet absorbers, and antioxidants are added and mixed. A method for molding a semi-rigid urethane product according to claim 1.