CH8 : Nylon Polymerization

"Huh?"

A sigh of admiration escaped my lips.

Before my eyes stood a structure reminiscent of a distillation tower. It was an advanced structure that didn't match the shabby factory at all.

'Isn't this a distillation tower? Come to think of it, it seems a bit outdated, being a batch system.'

Upon closer inspection, the cylindrical metal containers were not integrated but separately arranged.

It was not a facility for distilling crude oil.

It felt like an experimental apparatus for synthesizing high molecular compounds, something one might have used in the early 20th century.

"Who are you?"

"Hello, sir. I'm Woo Chan-soo from Daese Industries. I came in after seeing the sign."

An old man with a head full of white hair appeared from somewhere, and I greeted him.

"I'm not the boss. The boss is my son; I'm just the guard here."

"What?"

He didn't look like a guard.

His scrawny body and sharp gaze exuded an aura that went beyond peculiar, bordering on extraordinary.

"Anyway, why are you here?"

"I'm looking for a yarn supplier. I was wondering if I could get nylon yarn here."

"Nylon, huh? Young people these days, doing all sorts of things."

"I saw the signboard saying this is a nylon specialty store."

"Yeah, got it. Since you're here, let's have a meal first. Then we'll talk about the yarn."

"What?"

The old man insisted that I eat first.

Come to think of it, it was well past lunchtime.

"What's the matter? Don't want to eat in a place like this?"

"No, it's not that..."

"Then come inside. You look like you've been wandering around without a meal. Even the grandest sights require a full stomach."

The old man nudged me inside the factory with a casual wave of his hand.

"Who's the young man?"

"I don't know, he says he's a fabric merchant looking for nylon. He hasn't eaten, though."

"He must eat. Everyone works to live."

"Stop talking and set a place for him."

"Come on in. If you skip meals, you'll get sick."

"Today's meal is radish greens soup. We've put some meat in it, so it should be good."

It seemed like a family-run factory.

Judging by the elderly couple at the table and the young man with a similar face, it was almost certain.

The meal was nothing special.

A large bowl of barley rice mixed with various vegetables, red pepper paste, and a generous amount of sesame oil.

When a big bowl of that bibimbap was served with soup, the meal was complete.

The portion looked big, but maybe because I'd been walking around so much, I ate endlessly.

"You eat well for someone who looks so delicate."

"... Ah, yes. It's really delicious. Thank you."

Gulp. Gulp.

"Are you being trained as a newbie? Which merchant company are you from?"

"What?"

The person who looked like the son poured barley tea for me.

It seemed this was the boss that the old man mentioned.

"What kind of yarn did your senior ask you to find? He probably didn't tell you the specifications, so just tell me roughly what you need."

I must have looked like a new employee searching for yarn.

In the 60s and 70s, companies often made new employees sell goods under the pretense of training, develop new business partners without any leads, work part-time at dealerships, or even sign up for company insurance policies.

"We need a 120 denier nylon cotton blend yarn. The cotton blend ratio should be between 10% and 45%."

"Hmm... You seem well-trained for a newbie. You must have a good mentor."

"What kind of yarns do you have here?"

"There's no yarn. If you've eaten, you should leave."

"Father!"

Huh? I was talking to the son when the old man suddenly interrupted.

I was dumbfounded.

He claimed to be a guard but interrupted the conversation with the boss.

And then he said there's no yarn at a nylon yarn factory.

Today has been quite dynamic.

I got treated to a meal, obtained a factory, learned smuggling methods from a Japanese company branch, and now I'm being kicked out after getting a meal.

"What? Am I wrong? We can't even produce proper yarn. What's there to sell?"

"We can sell 10% cotton blend yarn, even if not the 45% blend. The quality is decent."

"What's decent about it! Who would buy yellowish nylon that breaks easily? Stop everything."

"Dear, if you talk like that, the customer will misunderstand."

The old man who jumped up was calmed down by the old lady. It felt like watching an old sitcom.

"What misunderstanding! No matter how crazy the world gets about money these days, I can't do that! We have nothing to sell. Leave!"

The old man pushed me out like a chicken, patting my bottom.

"Mother, take father away. Please."

"Okay, I got it. Young man, don't misunderstand. This old man is a bit senile."

"No, it's not a misunderstanding."

"Oh dear, I should die soon. I'm sorry, young man."

The old lady beat her chest and lamented.

It was hard to understand why she wanted to die and why she apologized to me.

It just felt like watching an old comedy skit.

"Why should you die?"

"Because you act like this. Come here. Don't interfere with our son's business!"

"Hey, let go of my arm."

The old lady dragged the old man away somewhere, and the son looked at me with an embarrassed expression.

"You must be flustered, right? My father gets angry over trivial things."

"Oh, yes. I understand."

"Despite how he seems, my father graduated from Kyungsung Vocational School's mechanical department."

"So he's a technician."

Wow, he was quite an impressive old man.

Kyungsung Vocational School was one of the few higher education institutions during the Japanese occupation.

It gathered the best talents in architecture, mechanics, electricity, civil engineering, and railways.

"Yes, he's skilled enough to make this nylon polymerization reactor himself, just by observing at a Japanese factory."

'Huh? This structure is a nylon polymerization reactor?'

No wonder it looked like a crude oil distillation apparatus; it was a polymerization reactor.

It seems petrochemical machinery has some commonalities.

Anyway, it was surprising that the old man was a prodigy, but it was even more amazing that he mimicked a nylon polymerization reactor just by watching.

'This must really be the early Hyesung Group.'

It's quite famous that all members of the Hyesung Group's founding family are engineers.

Although the group's size shrank as the textile industry declined in the late 20th century, it was once a powerful group.

"Do you produce nylon directly at this factory?"

"Yes, we use this equipment to create nylon lumps, and then the spinning machine over there extrudes it into yarn. To make blended yarn, we buy cotton yarn separately and twist it with our nylon to produce the final yarn."

Although there wasn't any nylon on the equipment, the explanation of the spinning process was clear.

He was not a novice at explaining to customers. He was every bit the boss.

"Can I see some samples?"

"Sure, this way."

We went further inside the factory.

Although neatly organized, no equipment was running.

The yarn samples seemed to have been produced a while ago.

"Have they been spun a long time ago? The nylon yarn looks discolored."

The nylon, which should be silver-white, was somewhat yellowish.

It looked like it had gotten dirty.

"It's not discoloration; our product is originally like this."

"You mean this is the original color?"

"Yes, our polymerization technology is still lacking. That's why my father said there's nothing worth selling."

The boss's face turned red as he explained, perhaps embarrassed from being humiliated by buyers often.

But his honesty was reassuring.

"Will it be okay if dyed?"

"It's fine for dark colors, but not for light colors as the chroma isn't great. If you purchase, we can price it at 150 won per pound."

150 won per pound, with an exchange rate of 270 won, that's... wait, less than 60 cents per pound?

That's quite cheap.

"It's cheaper than Gabon's product."

"Yes, since we polymerize it ourselves, we can sell it for that price and still make a little profit. Ha... Anyway, you should test how frequently it breaks when weaving fabric."

He was a very conscientious man.

Despite his awkward expression, he admitted that their yarn breaks easily.

"It breaks more often than Gabon's yarn, right?"

"Yes, I admit. No matter how we change the spinning conditions, we can't match the strength of Gabon's yarn."

"Spinning, you mean twisting the yarn?"

"That's right. The machine you see over there is the spinning machine. Have you ever twisted straw? Yarn also becomes stronger when twisted like straw."

The boss mimicked twisting straw with his hands.

It seemed off. Yarn shouldn't be twisted like that.

I don't know much about twisting straw, but I do know about twisting yarn.

In construction, strong cables for suspension bridges are made by twisting steel wires, and undersea cables in plants are also made by twisting outer sheaths.

It's crucial that they don't break, so you can't twist them like straw.

If you twist them like straw, the wires or sheathing materials try to revert to their original shape, causing the strength to decrease over time.

To make a strong cable, you place one wire at the center

 as the core and twist the rest around it.

The central wire ensures that the structure doesn't unravel and the strength doesn't diminish over time.

If that's not enough, heat is applied during the twisting process.

"Did you also mimic this equipment by observation?"

"Yes, my father made it himself."

It was impressive that he built it by hand, but he lacked the core know-how.

"The yarn strength issue seems solvable."

"What?"

"Let's run some yarn through it. I'll tweak the machine a bit."

"You'll tweak it?"

"Haha, don't worry. I won't break it."

I removed one yarn from the twisting disc of the spinning machine.

This yarn would now serve as the core to hold the structure.

Whether it's people or yarn, if you raise your hand and say 'standard!', everything around it falls into place.

It was so simple that the old man must have overlooked it.

The boss looked puzzled, but I gestured for him to run the machine.

Vrrrrrr.

"That should do it."

"Is this all the tweaking?"

"Of course. That's all."

I handed the twisted yarn to the boss.

He initially wore a dumbfounded expression but started tugging on the yarn and trembled in surprise.

After a few tugs, he even tried to bite it, as if in disbelief.

"What is this? What kind of magic is this?"

"It's not magic. Just a logical approach. When you twist, you need to set one yarn at the center. Twisting all yarns will easily unravel."

"Oh! I see! This is..."

The more I explained, the more the boss exclaimed in amazement.

"If the strength is still lacking, apply some heat. Raising the drum temperature slightly should help."

"You must be a doctor. I didn't recognize you."

"I'm not a doctor."

I'm not a doctor, but an engineer from the 21st century who has been through many trials.

"Would you like to operate the nylon polymerization reactor? I might be able to help."

"Yes, of course."

The boss, excited, ran over.

He loaded powder materials into the idle reactor, increased the temperature, and pressed various buttons.

It seemed everything was done manually, but he was quite adept.

After observing for a while, as the reactor felt warm, nylon flakes started pouring out like cheap cereal.

The nylon flakes, which should be transparent silver-white, were yellowish. That's why the yarns were that color.

The reaction speed seemed too high.

The equipment appeared to be a basic plant following the polymerization, extraction, and drying method.

It seemed just a matter of optimizing the catalyst and reaction control substances.

"Let me ask you a few things. What catalyst do you use?"

"Catalyst?"

"Do you just increase the temperature for polymerization?"

"Yes, we pour the raw nylon material caprolactam powder, mix it with acetic acid and water, maintain it at 150 degrees, then 190 degrees, and finally raise it to 260 degrees slowly."

The boss explained the polymerization conditions as if he trusted me completely, despite them being almost confidential.

"You use acetic acid. What reaction stabilizer do you use?"

Using acetic acid as a reactant should produce pure water, so discoloration was unlikely.

Then the culprit must be the reaction stabilizer.

"Reaction stabilizer?"

"I see. When you raise the temperature from 150 to 190 degrees, you need to add a stabilizer."

We often use the term 'explosive reaction.' In an industrial context, an explosive reaction is dangerous and hinders obtaining uniform quality, so it's intentionally slowed down.

That's where the reaction stabilizer comes in.

"I... didn't know. We don't add any other materials."

So they don't have the concept of a reaction stabilizer.

This, too, was a result of lacking fundamental knowledge.

"Alright. Try mixing in some titanium dioxide powder, about 0.5% of the total weight."

If unsure about what to use as a reaction stabilizer, titanium dioxide is a safe bet.

It mixes well with almost any material, has excellent heat resistance, and its oxide nature helps filter out organic impurities.

Ideally, 0.1 mol% should be added considering the chemical formula, but for small-scale plants, approximation suffices.

"Titanium dioxide?"

"You can easily find it at chemical suppliers."

"Understood. I'll make sure to get it and experiment."

The young boss's voice was filled with hope.

It seems I've secured the nylon yarn, at a price cheaper than Japanese smuggled goods, too.