本文介绍避孕套的发展历史和制造基本过程。
Background
Condoms are thin sheaths worn by men during sexual intercourse to prevent pregnancy and venereal infections. According to the 1995 National Survey of Family Growth, conducted by the National Center for Health Statistics in Hyattsville, Maryland, male condoms or prophylactics are the third most popular form of birth control—preceded only by female sterilization (29.5%) and birth control pills (28.5%)—with usage at 17.7%. They are also one of the most effective: research indicates that with correct use, failure rates are 2-3%. Most condoms are made of latex rubber, but they can also be made from lamb cecum or polyurethane.
In addition to their contraceptive value, condom use has been found effective in preventing the spread of sexually transmitted diseases. In 1986, the U.S. Surgeon General endorsed the use of condoms as the only currently available effective barrier against the transmission of Acquired Immunodeficiency Syndrome (AIDS). The spread of many other sexually transmitted diseases, such as chlamydia and gonorrhea, can also be virtually eliminated with the use of a latex condom. With the government touting the health benefits of condom use, manufacturers openly advertise their products, and retailers stock condoms in visible, accessible locations. Condoms, previously kept behind the prescription counter, are now found on most store shelves. Today in the U.S., 450 million condoms are sold each year.
Despite the wide variety of styles, there are few differences among the many latex condoms available on the market today. They can be straight-sided, contoured, ribbed, sensitive, or smooth. They may be treated with lubricants or spermicides. They can be blunt-ended or have a reservoir tip. Because the condoms undergo stringent testing before they are sold, quality is generally not a marketable issue. Hence, manufacturers attempt to build brand loyalty and market their products to specific target consumers.
Condoms made from lamb cecums—the blind pouch in which the intestines begin and into which the ileum opens from one side—are also available. However, they are more expensive than latex condoms, and while they prevent pregnancy, “skin” condoms are ineffective in preventing the transmission of sexually transmitted diseases. In 1994, the Food and Drug Administration (FDA) approved a polyurethane condom for sale in the U.S. The new condom has not been extensively tested for effectiveness in preventing pregnancy and sexually transmitted diseases.
History
The first recorded use of condoms was in Egypt in 1350 b.c. In 1564, the Italian anatomist Fallopius described a linen condom used to prevent venereal disease. The term condom is actually a corruption of the name of an 18th-century British physician, Dr. John Conton, who provided condoms to France’s King Charles II. The legendary lover Giovanni Casanova (1725-1798) used pieces of sheep intestine to protect himself against venereal disease. The first condom manufacturer in the U.S. was Schmid Laboratories. In 1883, Julius Schmid, a former
sausage skin-maker, acquired a business that manufactured bottle seals from animal membranes. Five years later, Schmid used his experience with sausage casings and capping skins to manufacture prophylactic sheaths from lamb cecum.
Even as Schmid was marketing his skin condoms, technology was progressing to allow thinner, more pliable, and less expensive condoms to became available. Vulcanization, the chemical linking of rubber particles that was originally developed in 1839 for use in automobile tires, made condoms strong, durable, and fit for consumer use. A form of rubber called latex was developed in the 1930s; this new material, combined with a mechanized dipping process, facilitated the mass production of condoms and lowered manufacturing costs.
The first condoms manufactured by Julius Schmid were formed from the cecum of lambs. As of 1990, condoms made from lamb cecum accounted for 5.5% of the market, and because of their higher price, for 20% of retail sales. This manufacturing process remains relatively unchanged since Schmid first manufactured condoms: the cecums are washed, defatted, and salted. The raw skins are then shipped to the finishing plants. New Zealand, which raises large numbers of sheep, is the primary source and initial processing center for most “skin” condoms.
Latex condoms account for most of today’s market. Because rubber latex is a natural material, it can vary greatly in strength and elasticity. Manufacturers add chemicals to the latex to stabilize and standardize the composition of the latex. Many brands also add talc, lubricants, or spermicides to the condoms before they are packaged.
The ManufacturingProcess
Collecting the raw materials
1、 Rubber latex is obtained from the milky fluid produced by various tropical plants. Latex is actually an emulsion or dispersion of tiny rubber particles in water, and ingredients added to the latex must be able to attach to the rubber particles during compounding.
Compounding
2、 Next, chemical additives are mixed to form a paste. This paste is then blended with the liquid latex in a process called compounding.
Storage
3、 The latex and chemical compound is then unloaded into drums for storage, where it remains for approximately seven days. During this period, vulcanization chemically strengthens the bonds of the rubber. The storage time also allows any Condom air, which might have been trapped in the mixture during compounding, to escape.
Dipping
4、 The compound is then added to the dipping or condom-forming machine. The dipping machine is a long, hooded machine approximately 100 feet (30.5 m) in length. Thick tempered glass rods move along a closed belt between two circular gears. The belt drags the rods, which are called mandrels, through a series of dips into the latex compound. The mandrels rotate to spread the latex evenly. Several coats are required to build the condom to its required thickness. Between each dip, the latex is hot air dried.
5 、After the final dipping and drying, the condoms automatically roll off the mandrels. A machine shapes and trims the ring of latex at the base of each condom.
Tumbling
6、 Next, the condoms are put in a tumbling machine, where they are coated with talc or another similar powder to prevent the rubber from sticking to itself.
Testing
7 、After a curing period of several days, the condoms are sampled by batch and tested for leaks and strength. The first such test is the inflation test, in which the condom is filled with air until it bursts. Condoms are required to stretch beyond 1.5 cubic feet, about the size of a watermelon, before bursting. This test is considered most important because the elasticity of the condom keeps it from tearing during inter-course.
8、 In the water-leakage test, the condom is filled with 10 ounces (300 ml) of water and inspected for pin-sized holes by rolling it along blotter paper.
9、 Condoms are also tested electronically. This involves mounting each condom on a charged stainless steel mandrel. The mandrel is passed over by a soft, conductive brush. If pin holes are present, a circuit will be established with the mandrel, and the machine will automatically reject the condom.
Packaging
10、 Condoms that have successfully passed these tests are rolled by a machine. Rolling the condom makes it easier to package and use. Lubricant and spermicide may be applied by a metering pump just before the top wrap is added in the foiling process.
Quality Control
Condoms are classified as Class II Medical Devices. According to the Medical Device Amendments of 1976 of the FDA, the FDA is required to inspect each condom manufacturing plant at least once every two years. All electrical and mechanical equipment must be impeccably maintained. Condom-dipping machines are designed to operate continuously; if they remain idle, their mechanisms can get clogged and rust. During any downtime, partially cured compound cannot be left in the dip tank because it could contaminate future production.
All condoms sold in the U.S. must comply to specifications that were voluntarily developed by condom manufacturers and adopted by the FDA. Condom measurements can range from 5.8-7.8 inches (150-200 mm) in length, 1.8-2.1 inches (47-54 mm) in width, 0.001-0.003 inches (0.03-0.09 mm) in thickness (although most condoms range between 0.002 and 0.0024 inches), and the weight cannot exceed 0.07 ounces (2 grams). Additionally, physical characteristics must include a minimum tensile strength of 15,000 pounds psa and elongation before breakage of 625%.
The FDA reviews U.S. company records and spot checks batches for cracking, molding, drying, or sticking latex. The organization also tests every lot of imported condoms. Upon sampling, lots will not pass inspection if they reveal greater than 4% failure with respect to the above dimensions, 2.5% failure with respect to tensile strength and elongation, and 0.4% failure due to leakage.
The Future
Manufactured by Chicago-based Female Health Co., the Reality condom for women has been on the market and available through family-planning clinics in the U.S. since August 1994. It has been sold in 12 European countries since 1993. The female condom is a long polyurethane sheath with one open ring and one closed ring that is anchored between the women’s cervix and vagina. According to Female Health Co., these condoms are 40 times stronger than latex; each costs approximately $3, compared to about $.64 for male latex condoms.
Research, started in 1988, lead to the development of the new polyurethane male condom, which also went on the market in 1994. The new condom is said to be just as strong but only one-tenth as thick as the latex condom. It is recommended for people who are sensitive to latex condoms.
Where To Learn More
Book
Murphy, James S. The Condom Industry in the United States. McFarland and Company, Inc., 1990.
Periodicols
“How Reliable Are Condoms?” Consumer Reports, May 1995, pp. 320-25.
Goldberg, Stephanie B. “Birth Control Update: Specialists Recommend Reviewing Choices As Life Changes.” Chicago Tribune, March 5, 1995, pp. 1, 6.
— Susan Bard Hall
From：www.madehow.com