Method for surface modification of synthetic artificial and natural polymers and polymer compositions using metals, non-metals and gases

A low energy electron beam of ions of an element to be imparted in polymeric material is formed and accelerated, the beam being subjected to electromagnetic separation so that only a high purity stream of the ion of this element impinges upon the substrate for implantation herein.

FIELD OF THE INVENTION 
This invention relates to a method of surface modification of both 
synthetic, (artificial) and natural polymers and polymer compositions, 
using metals, non-metals and gases. This method is applicable to surface 
modification of the properties of synthetic polymers of polycondensation, 
polyaddition and monomer and polymerization types including elastomers; of 
both synthetic or artificial fiber fabrics; of both artificial and natural 
polymers such as leathers, wool, cotton, wood-cellulose materials etc; of 
resins and varnishes. All of the above said materials are referred to 
hereinafter as the "polymers". 
BACKGROUND OF THE INVENTION 
Methods of surface modification of polymer materials are well known and 
include metallization and treatments with gaseous or other substances. 
The most frequently used of these methods, i.e. metallization, suffers the 
following principal drawbacks: poor adhesion between the metal coating and 
polymer surface; a requirement of both preliminary treatment of the 
polymer surface and application of additional fixing varnishes or other 
types of coating; working in a harmful environment composed of chemicals 
with toxic and cancerogenic action, etc. 
Surface modification of polymers by non-metals has not been accomplished up 
to date. 
Current methods of surface modification of polymer materials using gases 
are based either on heat treatment or electrical discharge, performed in 
the environment of the respective gases. The main disadvantages of these 
methods consist of: 
(a) difficult and improper control of both the quantity of diffused gas and 
the properties of thus modified surface, and 
(b) poor reproducibility of the process. 
A process for the modification of surface properties of semiconductors and 
metals as well as some organic dielectrics is in current use, which is 
called "ion implantation", i.e. a process, in which the solid surface is 
subjected to a bombardment with accelerated ions of given chemical element 
thereby penetrating it. The process of ion implantation has not been 
applied to polymeric matters. 
OBJECT OF THE INVENTION 
The object of this invention is to provide a method for surface 
modification of synthetic, artificial and natural polymers and polymer 
compositions, using metals, non-metals and gases, this method being 
universal, of high efficiency and permitting materials having better 
properties of the modified surface and materials with new properties to be 
obtained thereby. 
DESCRIPTION OF THE INVENTION 
The method for surface modification of synthetic, artificial and natural 
polymers and polymer compositions using metals, non-metals and gases, 
according to the invention, comprises implanting accelerated ions of any 
chemical element in the polymer material at low energies, mainly within 
the range of from 10.sup.2 to 10.sup.7 electronvolts. The process of 
implantation is accomplished at low, room or high temperatures of the 
polymer material, these temperatures being within the limits of its 
resistance. The quantity of implanted ions (or the so called "dose of 
implantation") is 10.sup.10 to 10.sup.23 ions/cm.sup.2. The current (i.e. 
density of the ion beam) is of from 10.sup.-8 A/cm.sup.2 to 10.sup.-2 
A/cm.sup.2. The depth of penetration of the ions implanted into the 
polymer material is up to 10.sup.-6 m. 
This method is applicable for the implantation of ions of all the elements 
included in the Periodic Chart into all types of polymer materials. 
Accelerated ions of given chemical element are implanted into the polymer 
materials subject to a surface modification. For this purpose, ions of a 
given element (together with ions of other substances arising directly 
from this chemical element or from its compounds) are obtained within an 
ion source. The ions thus obtained are accelerated and passed through an 
electromagnetic separator wherein they are separated based on their 
masses, and the ions of a selected element are directed to the material 
being treated. This electromagnetic separation of the ions ensures an 
absolute purity of the implanted element (at an isotopic level) and makes 
the implanting installation universally applicable. If a high purity of 
the element which is implanted is not required by the technological 
purposes of the process, a simplification of the installation is possible 
by elimination of the electromagnetic separator. A high precision dosage 
of implantation is possible by measuring the ion beam density during the 
process of implantation and period of its action upon the polymer 
material. Depending on the energy and atomic number of the accelerated 
ions and the type of polymer material used, a certain depth of penetration 
of accelerated ions is reached and a space modified layer is formed, 
having a modified and qualitatively new structure. 
This method can be used in the metallization of polymer surfaces by ion 
implantation especially for: creation of thin metal conductive layers on 
various plastics; coating by metallization of foil materials for 
capacitors; cooling by metallization of polymer surfaces having both heat 
and light reflective properties intended for agricultural needs, civil 
engineering and solar energy recovery; antistatic coatings on parts used 
in surgery and antiseptic coatings with medical application; coating by 
metallization of fabrics having heat reflective properties, intended for 
the preparation of clothes, sport articles, articles for everyday use and 
decorative use; and improvement of surface properties of wood boards and 
marking of securities. 
Metal implantation modified polymer surfaces can serve as a stable sublayer 
for the application of metal coatings thereto by known methods so as to 
fix the metal of the coating onto the implantation modified metal sublayer 
rather than onto the polymer material. Moreover, the method of ion 
implantation modification of polymers provides for successive complex 
implantation of an arbitrary number of metals. 
Polymer materials with their surface modified by non-metal implantation can 
be used for semiconductor elements (such as layers of silicon, germanium, 
selenium, tellurium, etc) on plastic supports; implantation of carbon to 
form new phases; thin heat resistance coatings based on silicon; inclusion 
of various non-metal admixtures having an effect on the process of ageing 
(i.e. photo, electrical, mechanical ageing, etc) of polyethylene 
modification of the surface optical properties. 
The layers formed by non-metal implantation can serve as sublayers for an 
additional application of coatings with various substances as well as by 
other known methods. 
Polymer materials modified by gas implantation can be used: in increasing 
the adhesiveness of polymer surfaces to paints, adhesive compositions and 
printing inks; and for improvement of the surface quality of packing 
materials and development of new packing materials of useful properties. 
Polymer materials modified by gas implantation can serve as sublayers for 
application of coatings by other known methods. Simultaneously, the method 
ensures the possibility of implanting successively an arbitrary number of 
elements for the gaseous state. 
The advantage of the method of the invention, is that ions of the required 
metal or non-metal can be produced in the ion source while using an 
insignificant quantity (i.e. dozens of square meters of area are treated 
with a quantity of the order of grams) of low price salts, essentially 
chalcogens of low melting points, without any limit of their purity being 
set, due to the electromagnetic separation, which ensures an absolute 
purity of the element being implanted. 
The other advantages of the method so proposed are as follows: a strong 
bond between implanted metal and polymer material is formed, ensured by 
internal structural bonds, where said metal forms a layer, which is not 
practically affected by mechanical actions (i.e. the layer does not crack 
or disconnect when rubbed, folded, crumpled etc.). Moreover, the adhesion 
force of the implanted layer is so high that the need for additional 
fixing varnished and coatings as well as preliminary treatment of the 
polymer surfaces is eliminated. 
When necessary, the polymer surface can be metallized using a metal of 
maximal purity (at an isotopic level) so that high precision control of 
the quantity of metal implanted is possible by measuring the ion current 
during the process of implantation. 
The surface electrical resistance of the polymer materials can be varied 
(i.e. reduced) in a wide range (of from 10.sup.14 Ohms to 10.sup.6 Ohms or 
less) according to the dose of the metal being implanted.

EXAMPLES 
The following examples throw more light on the invention: 
1. Aluminum ions are implanted into an impregnated fabric (Nylon 6) under 
the following conditions: 
E=16 KeV, D=10.sup.16 ions/cm.sup.2, I=10 .mu.A/cm.sup.2. 
2. Tin ions are implanted into a low density polyethylene foil (Ropoten 
OB-03-110) under the following conditions: 
E=40 keV, D=7.10.sup.16 ions/cm.sup.2, I=4 .mu.A/cm.sup.2. 
3. Nickelous ions are implanted into a cotton fabric under the following 
conditions: 
E=26 keV, D=6.10.sup.16 ions/cm.sup.2, I=5 .mu.A/cm.sup.2. 
4. Aluminum ions are implanted into synthetic fabric (Jambolen) under the 
following conditions: 
E=26 keV, D=5.10.sup.16 ions/cm.sup.2, I=2 .mu.A/cm.sup.2. 
5. Boron ions are implanted in polyethylene foil under the following 
conditions: 
E=15 keV, D=2.10.sup.16 ions/cm.sup.2, I=2 .mu.A/cm.sup.2. 
6. Phosphorus ions are implanted into a polystyrene foil under the 
following conditions: 
E=30 keV, D=2.10.sup.16 ions/cm.sup.2, I=1 .mu.A/cm.sup.2. 
7. Silicon ions are implanted into a synthetic fabric under the following 
conditions: 
E=25 keV, D=10.sup.16 ions/cm.sup.2, I=2 .mu.A/cm.sup.2. 
8. Carbon ions are implanted into polypropylene under the following 
conditions: 
E=25 keV, D=5.10.sup.16 ions/cm.sup.2, I=10 .mu.A/cm.sup.2. 
9. Oxygen ions are implanted into a polyethylene foil under the following 
conditions: 
E=15 keV, D=10.sup.16 ions/cm.sup.2, I=5 .mu.A/cm.sup.2. 
In these Examples E is the energy of the accelerated ions in 
kiloelectronvolt, D is the dose of implantation and I is the density of 
the ion beam in .mu.A/cm.sup.2. 
In all of the above given examples the working vacuum was of the order of 
10.sup.-5 to 10.sup.-4 Torr. 
Polymers modified by metal or non-metal implantation showed a reduced 
surface electrical resistance in the range of from 10.sup.6 to 10.sup.7 
Ohms at the dosages given above.