초록 ▼

Apparatus and method for applying extremely thin coatings of liquid materials entering the apparatus at a viscosity in the range of up to 10,000 centipoises absolute viscosity through a combination of factors involving the use of at least four rolls of desired physical characteristics and roll speed

Apparatus and method for applying extremely thin coatings of liquid materials entering the apparatus at a viscosity in the range of up to 10,000 centipoises absolute viscosity through a combination of factors involving the use of at least four rolls of desired physical characteristics and roll speeds to continuously extract a relatively thick film from a pool of the liquid, reduce it to an ultra thin coating free of discontinuities, and unite the thin coating with a web.

대표청구항 ▼

A method of coating a web comprising the steps of: providing a pond of coating liquid having a viscosity up to 10,000 centipoises in upstream submerging relation with a first nip defining a gap of not less than about 0.0002 of an inch and not greater than about 0.015 of an inch formed between a firs

A method of coating a web comprising the steps of: providing a pond of coating liquid having a viscosity up to 10,000 centipoises in upstream submerging relation with a first nip defining a gap of not less than about 0.0002 of an inch and not greater than about 0.015 of an inch formed between a first metallic roll and a second metallic roll, both rotatable to a surface accuracy within the first nip of less than 0.0001 of an inch; passing said liquid downstream through said nip by rotating the first roll through said nip in an upstream direction and rotating said second roll through said nip in the downstream direction at a peripheral rate greater than that of said first roll; passing the liquid carried on said second roll through a second nip formed by said second roll and a third roll having a resilient peripheral surface of a Shore A durometer hardness of approximately 90; supporting said third roll in pressure nip relation with the second roll and rotating the third roll concurrently with the second roll through said second nip at a peripheral speed greater than that of said second roll by a factor substantially equal to the quotient of the thickness of material entering said second nip divided by the thickness of material leaving said nip; passing the material carried away from said second nip through a third nip formed between said third roll and a fourth roll having resilient peripheral surface of a Shore A durometer hardness of approximately 90; guiding a web through said third nip; and supporting the fourth roll in pressure nip relation with the third roll and rotating the fourth roll concurrently with the third roll through said third nip at the same peripheral speed as said third roll to receive and forward the web at said peripheral speed. Apparatus for coating webs comprising: a first roll and a second roll oriented in nip relationship to receive and maintain a pond of coating material at the upstream side of the nip therebetween and at a height submerging said nip, both of said rolls being transaxially inflexible and finished to a hard surface of radial uniformity less than 0.0001 of an inch rendering said rolls capable of holding a constant nip gas while passing liquid having an absolute viscosity of up to 10,000 centipoises; means for supporting said two rolls at a fixed nip gap; means for driving the first roll through said nip in an upstream direction; means for driving said second roll through said nip iN the downstream direction at a peripheral rate greater than that of said first roll; a third roll comprising a peripheral resilient material of a Shore A scale durometer hardness of approximately 90 supported in pressure nip relation with the second roll to form a second nip; means for driving of a third roll concurrently with said second roll through said second nip at a peripheral speed substantially greater than that of the second roll; a fourth roll comprising a peripheral resilient material of a Shore A scale durometer hardness of approximately 90 supported in pressure nip relation with said third roll to form a third nip; and means for driving said fourth roll concurrently with the third roll through said third nip at the same peripheral speed as said third roll, said third and fourth rolls being speedrated and adapted to receive the web and forward it at said peripheral speed through said third nip.