Foam Core Bedding with CBA by fjhuangjun



                     Foam Core Bedding with CBA

Choose a CBA with mechanical properties as close        • Divilette NQ G1 – Medium Viscosity System
as possible to the core material. Make sure that the       Designed for core bedding in highly stressed
CBA:                                                       structures.
• Is compatible with the core.
                                                        • Divilette NQ G1 HV –High Viscosity System
• Is compatible with the resin system.
                                                           Developed for butt joints in highly stressed
• Is completely cured even in thin layers/film, if         structures.
   not remove the film completely prior to priming.
• Does not give too high exothermal when used in        This is a general application guide for use with the
   thick layers.                                        DIAB Group’s line of core bedding adhesives. This
                                                        information is believed to be reliable but is not to
DIAB Group has a variety of core bedding adhesives      be construed as a warranty for which the DIAB
for composite sandwich construction. Available          Group assumes legal responsibility. Users should
putties for use with DIAB Group’s PVC foam core         undertake sufficient verification and testing to
include:                                                determine the suitability of their own particular use
                                                        of any of the information or products referred to
• Divilette 600 –Low Viscosity System                   herein.

   Designed for core bedding especially with grid       Each Divilette is unique and has its own technical
   scored materials.                                    specifications. For technical or application support
• Divilette SQ –High Viscosity System                   call the DIAB Group Technical Support Department
   Developed for butt joints and manual application.    and identify what you wish to accomplish with the
                                                        core bedding Divilette.


Getting Acquainted:                                     Handling Precautions:
Be prepared. Plan out the application process. Make     • DIAB core bedding adhesive is a styrene based
several test panels to gain familiarity with both the      polyester resin system.Treat it with respect.
Divilette and the core prior to working on the full
                                                        • Always use a respirator when working with
size part.
Storing Divilette:                                      • Avoid prolonged exposure to skin.Apply a barrier
Divilette should be stored at minimum 10°C and             cream and use latex rubber gloves. Cover exposed
maximum 30°C. Ideal temperature is 15 – 20°C               skin with barrier cream and wear disposable
Higher temperatures will shorten its shelf life.           clothing.
Properly stored Divilette should be good for about      • Avoid contact with eyes. Always wear eye
90 days.                                                   protection. If Divilette gets into eyes, flush with
                                                           water for 15 minutes and call a physician
Always keep the Divilette container closed until           immediately.
ready for use. Open containers will allow the styrene
to evaporate, changing the handling characteristics     • If Divilette is ingested, call a physician and seek
and gel time, and may allow condensation inside the        medical attention immediately.

                                      Foam Core Bedding with CBA - 1

Environment:                                               Therefore try to apply the Divilette within 24 hours
Mould tools and materials such as DIAB foams and           of the previous laminate. If not possible, contact your
Divilette shall have at least the same temperature as      laminating resin manufacturer’s representative for
the existing in the factory premises when laminating.      instructions on surface preparation and secondary
The putties are promoted to gel in 45 minutes at           • Grind off bumps and debris in the laminate.
23°C (with a 1.5% catalyst concentration of 50 %               Vacuum away any dust or surface debris.
MEKP). Higher temperatures will shorten its gel time.      • Never use compressed air since it contains
Lower temperatures will extend its gel time.
                                                              moisture and lubricating oils, which could
                                                              prevent good adhesion to the fibreglass skin.
• Never use Divilette if the temperature is below
   18°C or above 30°C.
                                                           Before you begin:
• Catalyze Divilette according to data sheet.              Before you begin dry fit the core material that is
• If Divilette is stored cold, allow it to reach room      being used for your application. Cut the material to
   temperature before using.                               fit and number them in sequence of their installation.
                                                           Stack them to one side and cover them with plastic.
Application Tools:
Gather all the tools you will need to measure, mix,        Premixing! Premixing! Premixing!
and apply the Divilette and core material.                 • Contents of Divilette will settle during storage
                                                              and shipment. Therefore ALWAYS premix prior
If you are going to trowel it make sure you have:             to catalyzation with a low shear air driven mixer.

• Scales                                                   Catalyzation
• Squeegees                                                • Pour a small amount of Divilette into a small
                                                              mixing container. Experiment with the Divilette
• Mixing Containers                                           and adjust the catalyst amount to obtain about a
• Catalyst                                                    45 minutes gel time. Refer to the specific product
• Low shear air driven mixer                                  data sheet for catalyzation specifics.

• Proper Trowels                                           • As you gain experience with using Divilette, the
                                                              amount of catalyst and Divilette can be increased
• Resin (if needed)                                           to speed the curing process. Remember that a
• Vibrating rollers                                           large amount of Divilette will gel much faster than
                                                              a small amount (with the same amount of
If it is going to be sprayed, make sure your spray
machine is working properly and that you have all
the necessary tools. Do not forget latex gloves, barrier   • Use a low shear air driven mixer to disperse the
cream and protective clothing.                                catalyst.Avoid high speed mixing, which entraps
                                                              air. Mix until Divilette is a consistent colour and
Laminate Surfaces:                                            consistency.
Divilette will only bond to clean, contaminant free        • After mixing pour the Divilette into a clean
surfaces. The longer a polyester or vinyl ester               bucket to avoid using un-mixed Divilette typically
laminate sits the more difficult it becomes to make           stuck onto the sides of the mixing bucket.
secondary bonds. This is due to degree of cure and
is a function of time.

                                        Foam Core Bedding with CBA - 2

Amount of Divilette                                  Test panel
The amount of Divilette per m is mainly depending    If it is the first time in a new application, always
on following three factors:                          make a test panel similar to the actual object to make
                                                     sure that correct amount of Divilette is applied and
1. Evenness of the laminate.                         check the curing time for the Divilette in the actual
2. Convex or concave bent surface (opens or closes   room temperature in which the product will be
   GS score)                                         made.
3. DIAB foam thickness (see table below.)
                                                     Regardless if a kit has been delivered ready-made by
DIAB Foam GSW   Amount of Divilette                  DIAB, or made by customer, it is recommended to
thickness, mm Depth of layer per m2/mm               place the kit in the mould and rectify if necessary.
     10                        Approx. 1,5           Mark with a pen (water derived) around the entire
     12                        Approx. 2,0           Divinycell kit to be able to apply Divilette with a
                                                     minimum of wastage.
     15                        Approx. 2,5
     20                        Approx. 3,0           Hand troweling
     25                        Approx. 3,5           Apply Divilette directly to the laminate and spread
     30                        Approx. 4,0           it with the appropriate trowel. Be careful to hold
                                                     the trowel perpendicular to the laminate surface so
     35                        Approx. 5,0
                                                     it will apply a uniform thickness.
     40                        Approx. 6,0
                                                     Please be aware that each different thickness and
1 mm/m2 = 1 litre of Divilette                       type of core material available from the DIAB Group
Note! Only recommended value. For curved surfaces    will use a different type trowel. Be sure to ask your
or uneven laminate the consumption will be higher.   DIAB Representative for the proper trowel for your

Curing amount                                        Spraying
Guide line at 23°C and mixing of 1,5% (weight)       Applying Divilette with a spray machine is relatively
MEKP (50%)                                           simple. Make sure you understand how to use the
                                                     spray equipment and check if it is working properly
Type of     Colour     Gel time/ Density             before starting.
Divilette              minutes
600         Blue       25 - 45   550 - 650           Check the Divilette thickness with a film thickness
                                                     gauge. Please refer to the recommended Divilette
NQ G1       White      45 - 70   600 - 700
                                                     thickness chart available on each of the individual
                                                     putties technical data sheets.


Vibrating                                            Contoured cores can be set into Divilette and
How you hold the core in place while the Divilette   expected to stay in place while the Divilette cures;
gels is determined by the type of core and the       plain sheets are more difficult.
complexity of the surface you are bonding to.

                                     Foam Core Bedding with CBA - 3

Never use weights to hold core in place while              Filling the kerfs with Divilette is important. A
Divilette gels. Weights cause the Divilette to flow        contoured core with the kerfs properly filled with
out from under the core causing an inconsistent            Divilette will prove to be 20% to 30% stronger than
bond line.                                                 one with unfilled kerfs.

Lay the contoured core into the Divilette. Start at        Installation Quality Control
one edge of the sheet and gently bend it into the          Before the Divilette gels, lift a corner of the core to
Divilette. Never set the core into the Divilette flatly.   see if there is sufficient Divilette thickness and
This will trap air and cause voids. Place the contoured    coverage.
style core into the Divilette scrim side up.
                                                           The core and laminate should be covered and the
Use a vibrating roller (a roller with a pneumatic          Divilette heavily stippled indicating complete
vibrating motor) to set the core.The vibrating roller      contact between the core and the laminate. You
vibrates the core into place, thus eliminating all the     should not see any unfilled cuts.
air voids as the Divilette is forced up through all the
cuts in the core. Vibrating rollers are available from     If there are voids, it means that there was insufficient
the DIAB Group.                                            Divilette to completely fill the kerfs. Remove the
                                                           sheet and scrape the Divilette off the laminate.This
NOTE: If applying the core scrim side down a resin         is where practice saves money and time.
primer coat must be applied to the core.


Work description step by step                              5. When the vacuum bag is in place, hoses have to
1. Lay down the GSW sheets with the scores against            be connected to the vacuum pump. In most cases
   the Divilette, press it down and adjust it by hand.        a couple of connections (10-15 m² per
   DIAB foam of quality H100 or higher density                connection) is to prefer. Check that a suction
   should be wet primed on the surface, which is              pressure as even a possible (0,3-0,4 bar) is
   laid against the Divilette. Use a primer of the same       obtained over the whole surface. When the
   type of resin as in the laminate building.                 Divilette starts to penetrate through the GSW
2. When the foam kit is in place a peel-ply may be            scores, an even grid pattern of Divilette shows
   applied. This is mainly done to avoid after-               over the whole foam surface after 5-10 minutes
   treatment when the Divilette has cured, such as            depending on core thickness.When all scores are
   sanding etc.                                               filled, reduce the suction pressure to 0,2 bar and
                                                              keep it constant until the Divilette starts to gel.
3. Then an air distribution net is placed over the            Thereafter the vacuum material can be carefully
   entire foam surface to distribute the air and              removed. Before the Divilette has cured
   achieve an even pressure over the surface to               completely any excessive Divilette can be
   eliminate air entrapment.                                  removed with suitable tools.
4 Apply the vacuum bag, ready-made in accordance           6. After the Divilette has cured, inspect the adhesion
   with over the whole surface and attach it with             by tapping on the foam surface with your fingers.
   tape against the single laminate outside the foam          If there is a block without adhesion, attach it with
   edge.                                                      Divilette.

                                        Foam Core Bedding with CBA - 4
After inspection and approval of the adhesion, grind    resin as in the laminate.The primer shall at least gel
off debris, which was glued to the surface during       before lamination.
installation. Scrim can be peeled off to verify bond.
Use a shop-vac to remove debris and dust.               If necessary start the lamination with a chopped
                                                        stranded mat (CSM) against the core.Then continue
Be sure your Divilette has fully cured and try to       with the structural laminate.
laminate your core as soon as possible to prevent it
from being contaminated with dust and moisture          Where the sandwich changes to single skin fibreglass,
from the environment.                                   taper the core out at about a 45° angle. This allows
                                                        the fibreglass skin to come together gradually
Prepare the core for the inner laminate, the attached   eliminating stress concentrations and voids.
core surface has to be primed with same type of

• We strongly recommend the use of DIAB core            • A finished bond line thickness of 0.75 mm is
  materials with our line of putties. DIAB putties        recommended.
  were formulated for specific DIAB core materials.

• We recommend DIAB trowels be used with your
  (DIAB Group’s) preferred core in order to obtain
  the correct Divilette film thickness.

                                      Foam Core Bedding with CBA - 5
                   DIAB TECHNICAL SERVICES
               A Complete Service from Design to Finished Product
    DIAB Technical Services was established to                                  When it comes to the construction of sandwich
  partner and help our customers maximize the                                composites we are able to draw on a broad skill base
  benefits provided by the DIAB sandwich concept.                            that covers everything from hand lay-up to resin
  Technical Services personnel are strategically located                     infusion and from limited to series production.
  around the world to provide advice and support                                Taking infusion as example, we have been
  wherever a project is located. They bring to a project                     involved in numerous projects over many years in a
  a unique set of skills and                                                                             wide range of industries,
  experience regarding the                                                                               producing both small and
  engineering              and                                                                           ultra large components
  construction of sandwich                                                                               (100 foot plus). Our
  structures.                                                                                            comprehensive services
     Our engineers have                                                                                  can include:
  unrivalled experience of                                                                                  Providing assistance
  both analytical design and Finite element analyis of                      A DIAB Technical Services with the selection of the
                                 a sandwich component.                      supervised trial infusion.
  finite element modelling of                                                                            optimum combination of
  sandwich        composite                                                                              fiber and core to ensure a
  structures.                                                                                            trouble-free introduction.
     As a result we are able to                                                                          Recommending the most
  offer the most cost-effective                                                                          appropriate machining
  solution. Numerical tools                                                                              methodology to optimize
  are ver y useful for                                                                                   core kit fitting and resin
  optimizing the structural Carrying out an hydraulic                       On site customer training by flow. Designing an infusion
  design of components that crush test for a customer.                      DIAB Technical Services.     strategy that includes
  have complex shapes and load cases. Analytical                             detailed proposals regarding equipment and
  methods provide a quicker and lower cost solution                          materials.
  for straightforward problems. Our strength is to                              Finally, we can provide both theoretical and
  choose the most appropriate design procedure for                           practical training of personnel and then directly
  each specific case and when necessary validate our                         assist a customer’s team with prototyping and
  findings with in-house testing.                                            infusion trials.
  The data contained herein may be subject to revision and changes due to development and changes of the material. The data is derived from
  tests and experience. The data is average data and should be treated as such. Calculations should be verified by actual tests. The data is
  furnished without liability for the company and does not constitute a warranty or representation in respect of the material or its use. The company
  reserves the right to release new publications in replacement. Customers should check that they have the latest issue, see


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                                                                                                                                                Mar 04

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