Section 3. Research and Development of Basic Technology
Item 6. Rubber Product Research and Development
Embarking on rubber product research
Kiichiro Toyoda also had an interest in organic chemistry. In December 1932, in the course of diversifying business operations, he established Shonaigawa Rayon Company which can be counted among organic chemistry related enterprises. From that December until October 1937, industrial property rights applications related to the manufacture of rayon resulted in four patents and five utility model rights being granted. This demonstrates that research into synthetic fibers was carried out side by side with automobile manufacturing related research activities.
In 1934, when entering the design phase of the Model A1 prototype passenger car, the body styling and chassis were modeled to a certain extent on the DeSoto cars from Chrysler. The brakes also were to be hydraulic brakes on all four wheels, similar to the DeSoto models.1 Since all passenger cars and trucks from Chevrolet and Ford at the time had mechanical brakes, this was a move into new territory. The adoption of hydraulic brakes meant that brake parts and brake oil needed to be imported, and research into these areas became a necessity.
In November 1934, Kiichiro hired the chemical engineer Fujinobu Kimura2 and instructed him to "look into all things chemical-related to automobiles", and to "try and see what could be manufactured in-house".3 Kimura examined and researched materials for automobile parts at the chemical laboratory within the research laboratory of the Steelmaking Department. Along with metals, he also analyzed organic materials. At that time, organic materials used for cars included tires, tubes, fan belts, anti-vibration rubber mounts for engine mounting and suspension parts, as well as brake oil.4
When research into hydraulic brakes started, studying brake oil was chosen as the first target of inquiry, because the equipment of the chemical laboratory was up to this task. From about 1935 was the time when hydraulic brakes were first found in imported cars and the start of their wider acceptance, so there was as yet no domestically produced brake oil worth researching.
The main component of brake oil at the time was vegetable oil, mixed with an alcohol-based solvent to obtain the required viscosity. Research at the chemical laboratory showed that adding diacetone alcohol to castor oil (a vegetable oil) was optimal in terms of adjusting the viscosity. In-house production of this brake oil was begun on a small scale, and continued at the Rubber Section of the Kariya Plant until about 1943, when the Rubber Section separated from Toyota Motor Corporation and became independent.5
Research efforts related to hydraulic brakes also included chemical analysis of rubber piston cups and boots used in the hydraulic brake cylinders made by Wagner in the United States. In 1935, equipment for trial manufacturing of rubber parts for hydraulic brakes was installed at a test plant for brakes, occupying about 260 square meters and adjoining the research branch of the Steelmaking Department on the east side. This included a rolling mill (8 by 20 inches) and press (20 by 20 inches). Experimental production at the facility began promptly.
Brake linings were another target for development. At the time, brake linings were made by compacting asbestos using a binding agent, usually asphalt, pitch, rubber, or phenol resin. As an extension of its research into rubber parts, the chemical laboratory also developed brake linings using asbestos fiber or fine powder turned into a paste by using rubber binder. After having been readied for production, these brake linings continued to be manufactured also after the Rubber Section of the Kariya Plant separated and became the Nagoya Plant of Kokka Kogyo, supplying the products to Toyota Motor Corporation.