NZ208389A - Producing matt and smooth zones on synthetic floor or wall covering - Google Patents

Description

208389 Patents Form No.5.

Patents Act 1953 COMPLETE SPECIFICATION "Process for the local matting of synthetic coverings and products obtained" WE, EUROFLOOR S.A., a Societe Anonyme organised and existing under the laws of Luxembourg, of Rue Neuve, 9501 Wiltz, Grand-Duchy Luxembourg, Luxembourg, hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- 208389 j V Process for the Local matting of synthetic coverings and products obtained The present invention relates to a process intended for the local matting of a synthetic covering surface, more especially a floor covering or wall covering based on PVC, and to the products obtained.

The majority of plastic coverings do not exhibit, at their surface, a sufficient difference between gloss and mattness to give certain zones of the surface a particular appearance. The said zones can for example be a design applied by printing onto a covering, or an imitation of 10 a joint in the case of a covering which is an imitation of a ceramic tile flooring.

In general the matt condition of the zone, which ' is achieved by means of a graining roll, disappears at least partially during subsequent heating - which may be 15 local - of the said zone.

P. L. S. A, UG-A-4,373/819 and FR--A-3/S31 ,009 are dooumarvta which—describe—various—tec hn i queo—i nt ended—te—achieve- 31 to I&7 *" °ca I—matt i ng. ;The present invention proposes to provide an im- ;20 proved process which makes it possible to achieve a high degree of mattness at the surface of a zone of a synthetic cover i ng. ;The present invention provides a process for obtaining matt zones and smooth zones on a synthetic covering, wherein there is deposited onto a foamable or non-foamable ^ support, on an area corresponding to a design or pattern at least one coating or print which contains at least one radiation initiator for polymerisation and, on the whole surface of the support, at least one coating based on cross-linkable monomer; wherein a pregelling and, at least locally, a graining operation is carried out; and wherein the coating based on a cross 1inkable monomer is polymerised by radiation initiation so as to fix its appearance only in the area covering the radiation initiator and thereafter a gelling is carried out which, by causing fluidisation of the coating, ;N.Z. PATENT Offlfifees the disappearance of the grained appearance in the -4JUNI$#n~cr:>ssl inkefl zone an^ may also cause expansion. ;- 2 - ;RECEIVED ;208389 ;5 By a spectral zone there is understood, in the widest sense, a range of temperature conditions, a range of frequency conditions and other condition ranges capable of decoinpos.i ng the initiator to form the free radicals or ions needed for chain propagation in a polymerisation 10 reaction. ;The process of the present invention thus makes it possible advantageously to separate the polymerisation initiation in the zones in quest ion, depending on the pro-ducts used, so that the polymerisation initiation energy 15 supplied to a first zone cannot initiate the polymerisation of the other zone. ;This separation of the effects thus makes it possible to polymerise a zone and fix Its appearance and then to polymerise the second zone without changing the appear-20 anee of the first zone. ;This process is thus particularly applicable to obtaining different degrees of mattness; thus, according to first variant of the process of the Invention, there is deposited on a foamable or non-foamable support, in 25 a first zone, an ink or an extender containing a polymerisation initiator and optionally containing a foaming inhibitor and, in a second zone which can optionally at least partially encompass the first zone, a coating based on cross 11nkabIe monomer which contains a thermal polymerisa-30 tion initiator; a pre-gelling is carried out at a temperature such that the decomposition of the thermal initiator is nil or negligible; a graining operation is carried out O at least locally, the coating of the first zone is poly merised by initiation with ultraviolet radiation so as 35 to fix its appearance and a gelling is carried out which, by causing the fluidisation of the varnish, causes the disappearance of the grained appearance in the non-cross-linked zone and may also cause expansion and thermal cross- ;208389 ;linking. ;This technique is obviousLy not limited to therraal initiators and/or ultraviolet initiators. According to the invention it is possible to use two different thermal initiators having different initiation tempe rat ures, or two ultraviolet initiators having different ultraviolet initiation frequencies. It is also possible to combine the abovementioned Initiators with one another or to combine them with other polymerisation initiators such as ionic initiators, which initiators can in turn be combined with one another. It is thus seen that the process of the invention permits numerous variants. ;It should also be noted that the first zone can advantageously be a joint between two tiles in the case of a covering which is an imitation of a ceramic covering. However, it can also represent any desired design. Accordingly, the coating or printing of the first zone can be effected on a foamable support or on a non-expandable or only slightly expandable support. ;According to a supplementary embodiment, at least one of the zones and preferably the zone of the joint in a tile design can contain an expansion inhibitor. ;The process of the invention also has the advantage that it permits graining the entire surface without 1t being necessary to provide a special graining roll controlled in accordance with the design or decoration of the covering, because the zone which is not polymerised after graining will be fluidised during the subsequent gelling treatment and will become smooth through surface tension. ;By way of examples of monomers suitable for carrying out the invention there may be mentioned the following compounds (without this enumeration implying any limitation): ethylene glycol dimet hacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, tri-ethylene glycol diacrylate, tetraethylene glycol dimethacrylate, tetraethy lene diacrylate, polyethylene glycol ;dimethacrylate, polyethylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, ;1.3-butylene glycol diacrylate, 1,4-butylene glycol diacrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanedioI diacrylate, neopentyl glycol diacrylate, neopentyl glycol dinethacrylate, (ethoxylated) bis-phenol A dinethacrylate, di- ;vinyIbenzene, divinyIto luene, trinethylo Ipropane trineth-acrylate, t rinethy I o Ip ropane triacrylate, pentaerythritol triacrylate, glyceryl trinethacrylate, pentaerythritol tetracrylate and pentaerythritol tetranethacrylate. ;To these compounds, which have at least two propagation sites, there nay be added a certain anount of nono-neric compounds possessing one propagation site. ;Particularly preferred conpounds are 1,4-butylene gLycol dimethacrylate and trimethylo Ipropane trimethacry-late. ;By way of example, and according to a particularly advantageous embodiment, the wearing layer which constitutes the second zone is deposited in an amount of 300 g per and consists of a mixture of 100 parts of a base varnish containing: ;- 100 parts of PVC obtained by emulsion polymerisation ;- 42 parts of plasticisers (phthalates) ;- 3 parts of stabilisers (barium/zinc) and ;- 15 parts of white spirit, ;12.4 parts of an acrylic monomer (R0CRYI® 980 - ROHM & HAAS) and 0.1 to 0.3 part of an 80% strength solution of cumyl hydroperoxide (thermal initiator) in cumene. ;By way of example, but without wishing to imply any limitation, there may also be mentioned the following thermal initiators: benzoyl peroxide, diisobutyryL peroxide, ;2.4-dichlorobenzoyI peroxide, diisononanoyI peroxide, deca-noyl peroxide, lauroyl peroxide, acetyl peroxide, succinic acid peroxide, bis-p-chlorobenzoyI peroxide, 2,5-dihydro-peroxy-2,5-dimethyIhexane, cumyl hydroperoxide, t-butyl hydroperoxide, p-menthane hydroperoxide, diisop ropy Ibenzene hydroperoxide, 1,1,3,3-tetramethyIbutyI hydroperoxide. ;208389 ;di-<n-propyt) peroxydicarbonate, diisopropyl peroxydicar-bonate, di-(sec.-butyI) peroxydicarbonate, di-(2-ethyIhexyI) peroxydicarbonate, dicyclohexyl peroxydicarbonate, dicetyl peroxydicarbonate, bis-(4-t-buty IcyclohexyI) peroxydicarbon-5 ate, t-butyIperoxyisopropyI monocarbonate, 1,1-bis-(t-butyl-peroxy)-3,3,5-trimethylcyclohexane, t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxy-2-ethyIhexanoate, . t-butyl peroxypivalate, t-butyl peroxyneodecanoate, t-butyl hydroperoxide, t-butyl-peroxymaleic acid, di-t-butyl di-10 peroxyphthalate, 2,5-dimethy1-2,5-bis-(peroxybenzoyI)-hex-ane, 2,3-dimethy1-2,5-b1s-CoctanoyIperoxy)-hexane, t-butyl peroctoate, t-butyl perbenzoate, acetyl eyelohexyIsuLphonyI peroxide, acetyl sec.-heptyl-sulphonyI peroxide, Methyl ethyl ketone peroxide, 2,4-pentanedione peroxide, cyclo-15 hexanone peroxide. ;^ Amongst these there is preferred 1,1,3,3-tetra- ;methylbutyl hydroperoxide, cumyl hydroperoxide, 2,5-dimethyl-hexane-2,5-dihydroperoxide, t-butyl hydroperoxide and 2,4-pentanedione peroxide and very especially cumyl hydro-20 peroxide used in amounts of at least 0.00012. ;Because a large number of these peroxides exhibit * excessive decompbsition at the usual working temperature it can be of value to add to them inhibitors for the decomposition of the thermal initiator, of the following type 25 (the enumeration not being intended to imply any limitation): benzoic acid, pyridine, phenol, benzyl alcohol, resorcinol, ethylamine, benzylamine, hydroquinone, pyro-catechol and pyrogallol. 3 It is also possible to use, as initiators, azo compounds of the AIBN (azo-bis-isobutyronitrile) type or inorganic compounds containing a peroxide bond.

These products are chosen in accordance with the temperature and pressure conditions employed and in accordance with the rate of production, taking into account 35 their ki net i cs.

By way of an ultraviolet polymerisation initiator there are preferably used the Merck products DAROCllrffi^ 1173 or DAR0CUR®1116 in amounts of 1 to 50X, preferably -4 208389 %, by weight of the Ink or of the extender.

Other compounds such as the following are also suitable (without this enumeration implying any limitation) benzophenone, 2-chIoro-thioxanthone, 2-methyl-thioxanthone, 2-isop ropyl-th1oxanthone, benzoin, 4,41-d1methoxybenzoin, benzoin ethyl ether, benzoin isopropyl ether, benzyldi-methylketal, 1,1,1-trichloro-acetophenone, 1-pheny 1-1,2-propanedione-2-(ethoxycarbonyI)-ox ime, di ethoxyacetophenone dibenzosuberone, Darocur® 1398, Darocur©1174 and Daro-cur® 1020.

It is also possible to use conventional expansion inhibitors, preferably trimellitlc anhydride (TMA), to achieve differential foaming.

The coating containing the crossI1nkable monomer as well as the initiator for the second zone contains, in the particular case of a thermal Initiator, from 1 to 50%, preferably 11%, by weight of monomer possessing at least two chain propagation sites, optionally mixed with monomers possessing one chain propagation site.

The Invention will be described in more detail with the aid of the attached Figures in which: Figure 1 shows the support used for the process of the invention, Figure 2 shows the first stage of the process, Figure 3 shows the covering after the second zone has been coated, Figure 4 shows the graining stage, Figure 5 shows the first polymerisation initiation and Figure 6 shows the finished product.

It should be noted that the description given with reference to particularly preferred embodiments of the invention is only given by way of example and is not in any way intended to limit the scope of the present invention. Variations in working method, such as the production of a relief by silk screen printing techniques, also belong to the invention, as does printing of designs by a silk screen technique.

X X 208389 According to one variant of the invention, it is also possible to complete the smoothing by surface tension which occurs during gelling either by carrying out a mechanical smoothing treatment with a roller or by carrying 5 out a - preferably slight- hot graining operation.

It 1s also within the scope of the invention to provide an exposure to infrared radiation at the end of the treatment, for example when the product leaves an expansion oven, so as to assist the operation of smoothing of 10 the product surface. supplementary embodiment provides, in order to facilitate the operations of producing the floor covering or wall covering and to be able to initiate the crossllnklng stages differently from one another, that the said second 15 zone can be initiated directly or by means of an agent for energy transfer by radiation, so that each of the initiation stages can be triggered by a physico-chemical effect specific to it. In this way it becomes possible to separate the polymerisation initiation in the zones 20 in question in accordance with the initiators and/or physico-chemical initiation effects used, so that the polymerisation initiation energy provided by radiation in a first zone is unable to initiate the polymerisation of the other zone.

This separation of the effects thus makes it poss ible to polymerise one zone and fix its appearance and then to polymerise the second zone without deterioration of the appearance of the first zone.

Advantageously, the initiation of polymerisation 30 of the second zone by direct radiation or via an energy transfer agent can be effected by X-rays, by an electron beam or gamma radiation.

In order for the energy transfer agent to be able to exert its effect fully, it must act on a product in 35 which sufficient mobility of the crossIinkable monomer is assured.

This condition is best realised from an industrial point of view by heating the product in an oven, preferably -s O . 208389 the oven in which the gelling and/or optional expansion is/are carried out in a conventional manner, or immediately on leaving this oven, when the product is still at a sufficiently high temperature.

In this way, the polymerisation in the first zone can be brought about by the techniques described above and thereafter the polymerisation 1n the second zone can be brought about by suitable physico-chemical means, and this can be done without major modifications to existing 10 production lines for floor coverings.

Of course the different initiation effects used 1n the respective zones will be so chosen as to have sufficiently different initiation effects to achieve the desired effect. By way of example, it could be difficult 15 to control an operation in which two different ultraviolet initiators, that is to say triggered by different ultraviolet radiation ranges, were used because the separation of the effects in the ultraviolet spectrum would be difficult to achieve.

The monomers used, the localised application tech niques in the various zones and,,in general, the overall .technological process is identical, mutatis mutandis, to that which has been described above.

The technique to be used for effecting the initia-25 tion in the said second zone by radiation means, using trimethylolpropane trimethacryI ate as the monomer, can be that described, for example, by Salmon and Loan, J.

Appl. Polym. Sci.,1_6, 671 (1972).

For carrying out in practice techniques which in-30 volve using electron beams it is in particular possible to resort to the "ELECTROCURTAIN" apparatus manufactured by Ateliers de Chariailles (Energy Sciences International) of Geneva (Switzerland), using sufficient energy to penetrate in depth the layer which is to be crosslinked, for 35 example using energy of the order of 175 KV for doses of 2 Mrad.

EXAMPLE 1 Preferably, the support consists of a substrate - 08389 1 and a coating, in an amount of 500 g/m , of a foamable pLastisol 2. On this foamable plastisol coating there is deposited (Figure 2) in one or more stages, in a first zone and in accordance with a decoration which is an imita-5 tion of a tile joint design 3, a conventional ink containing an expansion inhibitor and about 20X of the ultraviolet initiator DAROCURf® 1173 or 1116 and, in accordance with any desired decorative design 4, an ink containing an ultraviolet initiator. It is obvious that the ink can be re-10 placed by an extender (that is to say a solution without ^ dyestuff or pigment) depending on the decorative effect which 1t is desired to obtain. Advantageously, this deposition (of ink or extender) is effected by a photogravure printing technique.

Thereafter there is deposited (Figure 3) over the entire surface a transparent plastisol coating to serve as a wear layer 5, this coating containing an acrylic monomer (ROCRYL^ 980) and the thermal initiator, preferably cumyl hydroperoxide; next pre-gelling is carried out at 20 a temperature such that the decomposition of the thermal initiator is nil or negligible, that is to say at between 100 and 160 degrees.

Figure 4 shows the stage of graining the entire surface, by means of a graining roll, at a temperature 25 which does not permit polymerisation of the plastisol, that is to say at a temperature above 100°C under a pressure which depends on the degree of mattness desired. The pre-gelling and graining stages can be carried out ^ in a single stage using a sufficiently heated graining roll.

The pass under an ultraviolet lamp 7 (Figure 5) makes it possible to crosslink the zone containing the ultraviolet initiator so that the (grained) condition of this zone is fixed by crossIinking.

Thereafter, the product obtained is passed for from one minute to two minutes thirty seconds through an oven at about 200°C, this being intended to expand the foamable coating 2 in the areas which do not contain an — ID 208389 expansion inhibitor and to polymerise the zone containing the thermal initiator. During this polymerisation, the zone which has not been polymerised during the ultraviolet initiation undergoes fluidisation during gelling, and this has the effect of smoothing the grained surface, while the zone which ha3 been grained and crosslinked during the ultraviolet initiation retains its grained (matt) state. The product shown 1n Figure 6 is obtained.

EXAMPLE 2 The procedure followed is as in Example 1, but with the difference that the ink used contains 1 to 20X of benzoyl peroxide dissolved in the minimum amount of ether or of methyl ethyl ketone.

The coating deposited on the entire surface contains - as in Example 1 - the other thermal initiator, namely cumyl hydroperoxide. In this case, the desired effect 1s brought about by making use of the different initiation temperatures of the initiators used.

A first heat treatment (pre-gelling) is in effect carried out at 120°C, and this is followed by a graining operation and finally by a gelling and expansion stage at 180-200°C, which can be accompanied by a mechanical smoothing operation.

EXAMPLE 3 The procedure followed is as in Example 2, but using 1 to 20X of azoisobutyronitrile (AIBN) dissolved in the minimum amount of methyl ethyl ketone and added to the ink.

EXAMPLE 4 The procedure followed is as in Example 1, the PVC being replaced by a copolymer of vinyl chloride (95%) and vinyl acetate (5X), all the other components remaining as before.

The following composition was used: Parts by weight - VC/VA copolymer resin containing % of vinyl acetate 100.00 - Stabiliser (bariurn/zinc) 3.00 / 208389 - Cumyl hydroperoxide - Monomer (trimethylolpropane t r i -methacrylate) - Plast 1c i sers - Deaerating agent .00 57.00 3.3 0.33 The pre-gelling is advantageously carried out on a drum at 130°C; this temperature can even be exceeded, depending on the speed of travel of the product.

It is found that this composition makes it possible 10 to achieve better gelling and better smoothing. 3lOS3?1

Claims (21)

WHAT WE CLAIM IS:

1. A process for obtaining matt zones and smooth zones on a synthetic covering, wherein there is deposited onto a foamable or non-foamable support, on an area corresponding to a design or pattern at least one coating or print which contains at least one radiation initiator for polymerisation and, on the whole surface of the support, at least one coating based on crosslinkable monomer? wherein a pregelling and, at least locally, a graining operation is carried out; and wherein the coating based on a cross-linkable monomer is polymerised by radiation initiation so as to fix its appearance only in the area covering the radiation initiator and thereafter a gelling is carried out which, by causing fluidisation of the coating, causes the disappearance of the grained appearance in the non— crosslinked zone and may also cause expansion.

2. A process according to claim 1, wherein the radiation initiator of polymerisation comprises an ultraviolet polymerisation initiator which is applied locally, in an ink or an extender.

3. A process as claimed in claim 2, wherein said 2-hydroxy-2-methyl-ultraviolet radiation initiator comprises / 1-pnenyl-propan-l-one or 1- (4-isopropy Iphenyl )-2-hydroxy-2-methyl-'propan-l-one ( from MERCK)

4. A process as claimed in any one of the preceding claims, wherein at least the coating or ink containing the radiation initiator or the coating based on crosslinkable monomer comprises a coating containing an inhibitor for the expansion of the support.

5. A process as claimed in claim 4, wherein said inhibitor comprises trimellitic anhydride (TMA). ir\

6. A process as claimed^ claim 3 or claim 4, wherein an ink containing 1 to 50% by weight of 2-hydroxy-2-methyl-l-phenyl-propan-l-one is u^jed.

7. A process as claimed ^claim 3 or claim 4, wherein an ink containing 20% by weight of 2-hydroxy-2-methyl-l-phenyl-propan-1-one is used.

8 . A process as claimed in any one of Claims 1-6 , whereirj^ the coating based on a crosslinkable monomer contains 2 - 13 - v &1 ?ONo^9a?l .// 2083ttu to 50% by weight, of monomer possessing at least two propagation sites.

9. A process as claimed in claim 8 wherein the coating based on crosslinkable monomer contains 11% by weight of monomer possessing at least two propagation sites.

10. The process as claimed in any one of claims 1 to 8, wherein a relief is obtained by depositing a plastisol in accordance with a silk screen process.

11. A process according to any one of claims 2 to 10, wherein the ink or extender is deposited by a photogravure or silk screen or flexographic printing technique.

12. A process according to any one of claims 1 to 6, wherein the pre-gelling is carried out within a range of 100°C to 160°C.

13. A process according to any one of claims 1 to 12, wherein the graining is carried out at a temperature above 100°C, under a pressure which depends on the degree of mattness desired.

14. A process according to any one of claims 1 to 13, wherein finally an expansion of the foamable support is carried out at 200°C for 1 minute to 2 minutes 30 seconds.

15. A process according to any one of claims 1 to 14, wherein the pre-gelling stage and graining stage are carried out as a single stage using a heated graining roll.

16. A process according to any one of claims 1 to 15, wherein the product is heated on the surface by exposure to infrared radiation.

17. A process as claimed in claim 16, wherein the product is heated on the surface by exposure to infrared radiation on leaving an expansion oven.

18. A process according to any one of claims 1 to 16, wherein the smoothing effect due to the surface ten- \ sion resulting from the fluidisation occuring during gel--^Ling is completed by a mechanical treatment using a smooth 2083dJ or textured roller.

19. A process as claimed in Claim 17 wherein said hot oven is the oven in which the gelling and/or the optional expansion is/are carried out.

20. A product obtained by the process of any one of claims 1 to 19. •P. L. E. & A.

21. A process for obtaining matt zones and smooth 05 ClC^med \r* t.Wn\ I O.Ad SI zones on a synthetic covering^, substantially as hereinbefo- re described with reference to and as shown in the accompanying drawings. ^ EUROFLQQR S.A. by their authorised agents P ,L. BERRY & ASSOCIATES per: 0