JPH08143637A - Semi-hard polyurethane foam - Google Patents

Abstract

PURPOSE: To economically obtain a foam, useful as interior material such as instrumental-panel, upper part of a door-trim, arm-rest and head-rest, etc., of automobiles with minimized defective molding by incorporating a specific amount of a specific cross-linking agent. CONSTITUTION: The foam is obtained by mixing (A) a polyisocyanate such as polymethylene-polyphenylisocyanate, (B) a polyol such as polyether-polyol, (C) water (D) a foam stabilizer, catalyst or other additives, and (E) a crosslinking agent obtained from starting compounds expressed by the formula; (n=2, 3) and the OH value ranging from 500 to 1500mgKOH/g where the amount of (E) is 0.3-1.5 pts.wt. per 100 pts.wt. of (B). The compound of the formula is optimally diethylenetriamine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semi-rigid polyurethane foam used for automobile interior materials such as instrument panels, door trim uppers, armrests and headrests.

[0002]

2. Description of the Related Art As a method for manufacturing the above-mentioned automobile interior material,
A soft polyvinyl chloride skin is attached to the lower mold, and ABS resin,
A three-layer structure integral molding method in which a core material such as a PPG resin or a modified PPO resin is attached to an upper mold, and a semi-rigid polyurethane foam stock solution is injected onto the surface of the skin to foam and cure the material is used.
The automobile industry is losing international competitiveness due to the recent sharp appreciation of the yen, and is taking various measures such as reducing the number of parts and requesting parts manufacturers to reduce costs. Interior material manufacturers must also reduce manufacturing costs in accordance with this trend. As a method of reducing the cost of the interior material, firstly, the total cost is reduced by changing the soft polyvinyl chloride skin to TPO (thermoplastic olefin) and the semi-rigid polyurethane foam to PPF (PP foam). Although there is a method, the interior material is not suitable as an interior material for high-class vehicles because the surface feel is bad. A second method of reducing manufacturing costs is to accelerate the foam hardening reaction of semi-rigid polyurethane foam to increase productivity, reduce the number of molds and reduce fixed costs, but it is necessary to invest in remodeling existing equipment. Not preferable. A third method is to reduce the molding density of the semi-rigid polyurethane foam. In order to reduce the molding density of urethane foam, there are methods of increasing the amount of foaming agent (water) used to increase the expansion ratio, and using polyols, isocyanates, and amine catalysts that increase the expansion ratio. ,
That is, voids (hereinafter referred to as voids) inside the urethane foam, roughness of the urethane foam surface (hereinafter referred to as cell roughness) and the like frequently occur, and the product cannot be a product. In this way, there are some problems in various methods for reducing the manufacturing cost of interior materials,
The same issue has not yet been resolved.

[0003]

The present invention relates to the third method for reducing the manufacturing cost of interior materials,
The object is to provide a semi-rigid urethane foam with extremely few molding defects.

[0004]

The inventors of the present invention have arrived at the present invention as a result of extensive studies for the purpose of solving the above problems. That is, the present invention is a polyisocyanate, a polyol,
In the semi-rigid polyurethane foam obtained by reacting water and other auxiliaries, with respect to 100 parts by weight of polyol,
Hydroxyl value of 500 to 1500 mg KOH / gr obtained by using the compound represented by the following general formula (A) (Chemical Formula 2) as a base
The present invention relates to a semi-rigid polyurethane foam characterized by being obtained by using 0.3 to 1.5 parts by weight of the cross-linking agent, and a method for producing the same.

Embedded image (In the formula, n represents 2 or 3)

Examples of the compound of the general formula (A) include diethylenetriamine and triethylenetetramine, and diethylenetriamine is most preferable. The above compound is used as a base, and propylene oxide and ethylene oxide are subjected to addition polymerization to give a hydroxyl value of 500 to 1500 mgKOH.
/ Gr of cross-linking agent can be obtained. The weight ratio of propylene oxide: ethylene oxide is 90:10 to 0 :.
100 is suitable, and particularly preferably around 50:50. When the weight ratio of propylene oxide is 90% or more, the viscosity of the obtained cross-linking agent becomes high, which is not preferable in handling. The method of adding ethylene oxide may be a chipped type or a balanced type. The cross-linking agent thus obtained has a hydroxyl value of 500.
If it is lower than mgKOH / gr, the foam hardness will be low, and it will not function as a crosslinking agent.
When it is higher than H / gr, the initial reaction at the time of foaming becomes fast, which is not preferable.

The amount of the crosslinking agent used is suitably 0.3 to 1.5 parts by weight based on 100 parts by weight of the polyol. 0.
If the amount is less than 3 parts by weight, defective molding cannot be solved when the foam molding density is reduced. On the other hand, if the amount is more than 1.5 parts by weight, the soft polyvinyl chloride skin / urethane foam integral product discolors and deteriorates during heat treatment, which is not preferable. The crosslinking agent may be used alone or in combination with a known crosslinking agent. Known cross-linking agents include diethanolamine and triethanolamine. Polyol 1
0.0 to 1.0 part by weight is used with respect to 00 parts by weight.

As the polyol, known ones can be used, but particularly preferable ones are polyhydric compounds such as water or ethylene glycol, propylene glycol, diethylene glycol, glycerin, pentaerythritol, sorbitol and sucrose, and ethylene oxide and propylene. A polyether polyol obtained by addition-polymerizing one or more of oxides, butylene oxide, etc., having a functional group number of 2 to 4, and a hydroxyl value of 24 to 5
It is of 5 mg KOH / gr. In addition, polyester polyols are also used, and examples thereof include polyester polyols obtained from various glycols and adipic acid. Acrylic polyols can be used as well.

As the polyisocyanate, known ones can be used, but particularly preferable ones are polymethylene polyphenyl isocyanate (referred to as crude MDI and polymeric MDI, regardless of the manufacturing method thereof),
Alternatively, it is a prepolymer having a terminal isocyanate group obtained by reacting polymethylene polyphenyl isocyanate with a polyol.

The foam stabilizer is preferably an organic silicon compound, for example, L-5305 and L- manufactured by Nippon Unicar Co.
3600, L-3601, L-5309, SRX-274C, SF-2961, SF-2 manufactured by Toray Silicon Co.
There are 962 etc.

As the catalyst, an amine-based catalyst is mainly suitable. Examples include triethylenediamine, trimethylaminoethanol, N-methylmorpholine, tetramethylhexamethylenediamine, etc., and usually polyol 1
It is used in an amount of 0.25 to 1.00 parts by weight based on 00 parts by weight.

The equivalent ratio (NCO / OH) of isocyanate groups and hydroxyl groups in the production of semi-rigid polyurethane foam is
0.85 to 1.30, more preferably 0.95 to 1.1
0 is suitable. The semi-rigid polyurethane foam of the present invention can be manufactured by a manual method, a so-called hand mix method, or a method using a machine.
When using a machine, a so-called high-pressure foaming machine or low-pressure foaming machine can be used. Further, the semi-rigid polyurethane foam of the present invention can be manufactured by a method of pouring into a mold. In this case, the mold temperature is preferably 35 to 45 ° C.

[0012]

EXAMPLES In order to more specifically describe the present invention,
An example and a comparative example will be described. The results are summarized in Table 1. The numbers (parts) in the examples represent parts by weight unless otherwise specified.

[0013]

[Table 1]

The polyols, polyisocyanates, catalysts and crosslinking agents used in the examples and comparative examples are as follows. Polyol-A: A polyether polyol having a hydroxyl value of 28 mgKOH / gr obtained by adding propylene oxide and ethylene oxide to propylene glycol in a ratio of 80:20. Crosslinking agent-A: A crosslinking agent having a hydroxyl value of 760 mgKOH / gr obtained by adding propylene oxide and ethylene oxide to diethylenetriamine at a ratio of 50:50. Crosslinking agent-B: a crosslinking agent having a hydroxyl value of 450 mgKOH / gr obtained by adding propylene oxide and ethylene oxide to diethylenetriamine at a ratio of 50:50. Crosslinking agent-C: A crosslinking agent having a hydroxyl value of 1500 mgKOH / gr obtained by adding propylene oxide and ethylene oxide to diethylenetriamine at a ratio of 50:50. Crosslinking agent-D: Diethanolamine Crosslinking agent-E; Triethanolamine catalyst-A; Trimethylaminoethanol catalyst-B; 33% diethylene glycol solution of triethylenediamine. Isocyanate: A terminal isocyanate prepolymer having an isocyanate content of 29.0%, which is obtained by urethane-modifying Polymeric MDI (Cosmonate M-200 manufactured by Mitsui Toatsu Chemicals, Inc.) to glycerin with a polyether polyol having a hydroxyl value of 450 mgKOH / gr.

Example 1 100 parts of polyol-A, 2.8 parts of water, crosslinking agent-A
1.5 parts, 0.4 parts of catalyst-A and 0.2 parts of catalyst-B were mixed to obtain a polyol component. The polyol component was mixed with isocyanate to perform free foaming and mold foaming. In free foaming, the time when foaming starts (Creamtime, abbreviation CT), the time when the stick is pierced into the foam and the foam pulls the thread when the stick is pulled up (Geltime, abbreviation G).
T), and the time until foaming ends (rise time
The abbreviation RT) was measured. The foam density after foaming and curing was also measured. In mold foaming, a soft polyvinyl chloride skin is attached to a part of the lower mold of an aluminum test mold having an average thickness of 10 mm which is adjusted to 40 ° C. in advance, and a urethane stock solution is poured on it, and the upper mold is tightened at room temperature. After standing for 3 minutes, the obtained molded product was taken out of the mold, and the molded state of the foam (void, cell roughness) was observed. One day later,
The foam hardness was measured by applying an Asker-C hardness meter on the foam. Further, the integrally molded portion with the soft polyvinyl chloride skin was cut out and left in an oven at 110 ° C. for 400 hours, and then the discoloration and fading ΔE of the soft polyvinyl chloride skin was measured with a color difference meter manufactured by Tokyo Denshoku Co., Ltd. Also, the elongation value (E
L) was measured and the deterioration state was investigated. The results are shown in Table-1, which has a lower foam density than Comparative Example 1 and Comparative Example-2.
The void and the cell roughness like the above did not occur. Further, the foam hardness and discoloration of the skin were both satisfactory.

Example 2 The cross-linking agent of Example 1 was used in combination with the cross-linking agent-D.
Both free foaming and mold foaming were good.

Comparative Example 1 A conventional high-density prescription and high manufacturing cost. Comparative Example 2 The amount of water in Comparative Example 1 was increased from 2.4 to 2.8 parts to increase the degree of foaming, but voids and cell roughness frequently occurred. Comparative Example 3 The amount of the crosslinking agent used in the present invention was 0.2 parts, but voids and cell roughness were not improved. Comparative Example 4 2.0 parts of the crosslinking agent of the present invention was used, but the discoloration and fading of the epidermis after heat treatment was remarkably inferior. Comparative Example 5 1.5 parts of crosslinking agent-B was used, but the foam hardness was low and not satisfactory. Comparative Example 6 Although 1.5 parts of the crosslinking agent-C was used, CT of free foaming was accelerated, which was not preferable.

[0018]

According to the present invention, a semi-rigid urethane foam that does not cause molding defects such as voids and cell roughness even if the density of the urethane foam is reduced, and that maintains skin discoloration and fading after heat resistance and foam hardness is obtained. can get.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Ueda 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (2)

[Claims] 1. A semi-rigid polyurethane foam obtained by reacting a polyisocyanate, a polyol, water and other auxiliaries with 100 parts by weight of a polyol based on a compound represented by the following general formula (A) A semi-rigid polyurethane foam obtained by using 0.3 to 1.5 parts by weight of a crosslinking agent having a hydroxyl value of 500 to 1500 mg KOH / gr obtained as an agent. Embedded image (In the formula, n represents 2 or 3) 2. The semi-rigid polyurethane foam according to claim 1, wherein the compound represented by the general formula (A) (Formula 1) is diethylenetriamine.